krüger h, hahn a, kuhlmann a. influence of falls reduction on the cost-effectiveness of advanced hydraulic microprocessor controlled knee protheses in elderly patients with lower limb amputations. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018.doi: https://doi.org/10.33137/cpoj.v1i2.32041 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) influence of falls reduction on the cost-effectiveness of advanced hydraulic microprocessor controlled knee protheses in elderly patients with lower limb amputations henning krüger1, andreas hahn*2, alexander kuhlmann3 1 leibniz university hanover, germany. 2 otto bock healthcare, vienna, austria. 3 center for health economics research hannover (cherh), hanover, germany. * e-mail: andreas.hahn@ottobock.com doi: https://doi.org/10.33137/cpoj.v1i2.32041 introduction the assessment of cost-effectiveness and the use of health economical methods becomes of increasing importance when evaluating the impact of modern medical technology. the cost effectiveness of advanced hydraulic microprocessor controlled knees (mpks) had recently by shown by rand 1. a new generation of advanced hydraulic microprocessor controlled knee (mpk) components became available to address specifically the needs of elderly individuals the reduction of concomitant factors such as falls may significantly improve cost-effectiveness. objective aim of this investigation is to assess the cost effectiveness of advanced hydraulic mpks vs. non mpks in a population of elderly above-knee amputees. methods a health economical decision tree based model was developed on the basis of existing clinical results 2,3. the model population (n=1.000, transfemoral amputees, no gender specification) is of either vascular or non-vascular etiology and aged between 55 and 75 years. the incremental cost-effectiveness (icer) is calculated to assess the economic efficiency of advanced hydraulic mpks. depending on the etiology and the chosen prosthetic fitting, the risk of falls, the number of falls, the severity of injuries and the injury related mortality are modeled over a five years horizon. parameters related to costs and quality of live assessments are taken from the literature. to verify model assumptions and uncertainties in the chosen parameters a univariate analysis of the sensitivity is performed 4. results the comparison of mpk and non-mpks yields an icer of 16.910 $ per qaly for vascular and 19.848 $ per qaly for non-vascular etiology. the largest impact on the model is due to the health utility values and prosthetic costs. the fatality avoidance rate is 7 fold increased in the vascular population. figure 1. comparison of icer findings for elderly with rand results. conclusion results of the analysis indicate the cost-effectiveness of advanced hydraulic mpks in elderly patients with lower limb amputation. we highlight the specific advantages fur subjects with vascular disease. significance cost effectiveness of advanced hydraulic mpks could also be shown in the population of elderly transfemoral amputees. such findings may be supportive when https://doi.org/10.33137/cpoj.v1i2.32041 mailto:andreas.hahn@ottobock.com https://doi.org/10.33137/cpoj.v1i2.32041 krüger h, hahn a, kuhlmann a. influence of falls reduction on the cost-effectiveness of advanced hydraulic microprocessor controlled knee protheses in elderly patients with lower limb amputations. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018.doi: https://doi.org/10.33137/cpoj.v1i2.32041 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) arguing for successful coverage. further need for research was identified. references 1. liu et al., economic value of advanced transfemoral prosthetics. santa monica, ca: rand corporation, 2017. https://www.rand.org/pubs/research_reports/rr2096.html. 2. gerzeli s,torbica a, fattore g. cost utility analysis of knee prosthesis with complete microprocessor control (c-leg) compared with mechanical technology in trans-femoral amputees. eur j health econ. 2009 feb;10(1):47-55. doi: 10.1007/s10198-008-0102-9. epub 2008 apr 1. 3. seelen etal. costs and consequences of a prosthesis with an electronically stance and swing phase controlled knee joint. technol disabil 2009;21(1–2):25–34. doi: 10.3233/tad2009-0269 4. krüger, 2016, a cost estimation model for the extractive software-product-line approach. master thesis, university of magdeburg, germany, february 2016. http://wwwiti.cs.unimagdeburg.de/iti_db/publikationen/ps/auto/thesiskrueger.pdf disclosure krüger was m.sc. of the leibniz university hanover. hahn is full-time employee of otto bock healthcare. kuhlmann is senior research associate at the cherh of the university of hanover. https://doi.org/10.33137/cpoj.v1i2.32041 http://wwwiti.cs.uni-magdeburg.de/iti_db/publikationen/ps/auto/thesiskrueger.pdf http://wwwiti.cs.uni-magdeburg.de/iti_db/publikationen/ps/auto/thesiskrueger.pdf ghoseiri k, rastkhadiv m.y, allami m. evaluation of localized pain in the transtibial residual limb. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32028 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) evaluation of localized pain in the transtibial residual limb kamiar ghoseiri*1, mohammad yusuf rastkhadiv2, mostafa allami3 1department of orthotics and prosthetics, school of rehabilitation sciences, hamadan university of medical sciences, hamadan, iran. 2department of occupational therapy, school of rehabilitation sciences, hamadan university of medical sciences, hamadan, iran. 3janbazan medical and engineering research center (jmerc), tehran, iran. * email: k.ghoseiri@umsha.ac.ir doi: https://doi.org/10.33137/cpoj.v1i2.32028 purpose the socket is the main component of a prosthesis which surrounds the residual limb and transfers loads and motions between the residual limb and prosthesis. a misfit socket may lead to excessive stresses on the residual limb, pistoning of the prosthesis during walking, patient discomfort, pain, and skin damage. the quality of socket-skin interface directly affects quality of life, prosthesis use, and satisfaction from prosthesis in amputees. pain is a devastating condition that prohibits prosthesis use1-4. the present study aimed to evaluate pain threshold and tolerance of the transtibial residual limb to improve its socket design and fit. methods nineteen veterans with unilateral transtibial amputation participated in this cross sectional study. in supine position, the pain threshold and tolerance were evaluated at 12 locations on the residual limb with indentation method. pain values at different locations were compared to each other. correlations of pain values with demographic characteristics were explored. results pain threshold and tolerance differed at all locations; however their difference was significant in mid-patellar tendon, medial tibial flare, and distal end of the tibia. the lowest and highest pain threshold and tolerance was distal end of the residual limb and mid-patellar tendon, respectively (figure 1). there were no significant correlations between pain and demographic characteristics of participants except for the daily hours of prosthesis use. conclusion although the mid-patellar tendon and distal end of the residual limb were the best and worst load tolerant regions in transtibial amputees, due to the small difference between pain threshold and tolerance limits (range of 11-21 n/cm2), a small pain may be transformed to an intolerable pain, skin irritation and scar. therefore, transtibial prosthetic sockets should be designed based on load tolerability of the residual limb. figure 1: the results of pain threshold and tolerance at different locations on transtibial residual limb significance • residual limb pain may be sourced from a misfit prosthetics socket. • in transtibial residual limb, the lowest and highest pain threshold and tolerance was related to the distal end of the residual limb and mid-patellar tendon, respectively. • due to the small difference between pain threshold and tolerance limits, a small pain may be transformed to an intolerable pain. • transtibial socket design should be based on pain tolerability of the residual limb. mailto:k.ghoseiri@umsha.ac.ir mailto:k.ghoseiri@umsha.ac.ir https://doi.org/10.33137/cpoj.v1i2.32028 https://doi.org/10.33137/cpoj.v1i2.32028 ghoseiri k, rastkhadiv m.y, allami m. evaluation of localized pain in the transtibial residual limb. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32028 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) references 1. dou p, et al. pressure distribution at the stump/socket interface in transtibial amputees during walking on stairs, slope and non-flat road. clin biomech (bristol, avon); 21, 1067-73, 2006. doi:10.1016/j.clinbiomech.2006.06.004 2. zhang m & lee wc. quantifying the regional load-bearing ability of trans-tibial stumps. prosthet orthot int; 30, 25-34, 2006. doi:10.1080/03093640500468074 3. fischer aa. pressure tolerance over muscles and bones in normal subjects. arch phys med rehabil; 67, 406-9, 1986. 4. lee wc, et al. regional differences in pain threshold and tolerance of the transtibial residual limb: including the effects of age and interface material. arch phys med rehabil; 86, 6419, 2005. doi:10.1016/j.apmr.2004.08.005 disclosure the authors report no declarations of interest. however, the financial support of the research was done by the janbazan medical and engineering research center (jmerc). acknowledgments the authors would like to thank the veterans and martyrs affairs foundation (vmaf) for their cooperation with the study. https://doi.org/10.1016/j.clinbiomech.2006.06.004 https://doi.org/10.1016/j.clinbiomech.2006.06.004 https://doi.org/10.1080/03093640500468074 https://doi.org/10.1080/03093640500468074 https://doi.org/10.1016/j.apmr.2004.08.005 https://doi.org/10.1016/j.apmr.2004.08.005 balkman g, samejima s, aoki d, hafner b.j. japanese translation of the prosthetic limb users survey of mobility. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32017 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) japanese translation of the prosthetic limb users survey of mobility geoffrey balkman*, soshi samejima, david aoki, brian j. hafner department of rehabilitation medicine, university of washington, seattle, wa, usa. * email: gbalkman@uw.edu doi: https://doi.org/10.33137/cpoj.v1i2.32017 introduction patient-reported outcome measures (proms) are used by prosthetists to assess and communicate effectiveness of prosthetic interventions. the prosthetic limb users survey of mobility (plus-m) is a prom developed to evaluate lower limb prosthetic mobility.1 valid and reliable translations of prosthetics-specific proms, like plus-m, do not exist for japanese-speaking patients. the purpose of this research was to translate plus-m to japanese using rigorous translation guidelines in order to maintain the meaning and applicability of items across both languages. methods translation efforts followed recommended processes and best practices.2 first, plus-m items (n=44), response options and instructions were independently translated by investigators from english to japanese. translators met with the principal plus-m developer to discuss the forward translations and resolve any discrepancies. reconciliation guidelines3 were used to code and document decisions. the reconciled translation was back-translated from japanese to english by a bilingual collaborator. investigators compared the back-translation relative to the english instrument, and the developer identified items that required modification. all translations and revisions were recorded in a comprehensive translation document. four expert reviewers in japan evaluated the translation and provided additional suggestions for revisions. results twenty-one items had to be removed or revised in the translation process. one item without a comparable situational context was removed during forward translation. the plus-m item that described shag (highpile) carpet was removed because that type of carpet is not common in japan. seventeen items were revised grammatically to maintain the intended purposes of the original english items. for example, a plus-m item that asks respondents how well they can “step off” an escalator was back-translated as how well one could “get off” the escalator. the investigators added additional terms to the translation (i.e., “get off an escalator step over step”) to ensure the item was read and interpreted as intended. more substantial revisions were made to three items to address cultural or environmental differences. for example, the expert reviewers noted that the term “block” in the plus-m item, “are you able to walk a block on flat ground?” does not translate to japanese. the investigators, in consultation with the expert reviewers, suggested the phrases “from one traffic light to the next,” “50 – 100 meters,” or “from one intersection to the next,” could be used as alternatives. the developer preferred the phrase with “intersection.” this revision changed the original item, but was understandable in japanese and aligned with the developers’ intended meaning (i.e., walking moderate distances outdoors). the final translated items were used to create 7and 12-item short forms suited to administration in clinics or research studies (figure 1). figure 1. japanese translation of plus-m short form mailto:*%20email:%20gbalkman@uw.edu https://doi.org/10.33137/cpoj.v1i2.32017 balkman g, samejima s, aoki d, hafner b.j. japanese translation of the prosthetic limb users survey of mobility. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32017 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) conclusion the plus-m japanese version is ready for testing by prosthetics experts in japan. cognitive interviews with japanese prosthesis users will assess the clarity and comprehensiveness of items. large-scale administration and comparison to us norms will be conducted to quantitatively assess equivalence between the original and the japanese translation of plus-m . significance international and cross-cultural comparisons of key health outcomes, like mobility, can help to assess the relative effectiveness of prosthetic interventions. use of standardized outcome measures, like plus-m, can facilitate comparisons and improve the standard of care worldwide. references 1. hafner bj, et al. construct validity of the prosthetic limb users survey of mobility (plus-m) in adults with lower limb amputation. arch phys med rehabil. 2017;98(2):2775. doi:10.1016/j.apmr.2016.07.026 2. eremenco sl, et al. a comprehensive method for the translation and cross-cultural validation of health status questionnaires. eval health prof. 2005;28(2):212-32. doi:10.1177/0163278705275342 3. koller m, et al. the process of reconciliation: evaluation of guidelines for translating quality-of-life questionnaires. expert rev pharmacoecon outcomes res. 2012;12(2):189-97. doi:10.1586/erp.11.102 disclosure there is no current or pending support pertaining to this project. acknowledgements the authors thank toshiki kobayashi, phd, kazuhiro sakai, masanori shimamura cpo, and noriaki maeda, phd for their review of the plus-m japanese translation. https://doi.org/10.1016/j.apmr.2016.07.026 https://doi.org/10.1177/0163278705275342 https://doi.org/10.1586/erp.11.102 mathis s.l. factors associated with mobility apprehension in amputees. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32040 1 open access abstract (oral presentation) aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 factors associated with mobility apprehension in amputees shannon l. mathis*1, 1the university of alabama in huntsville, usa. * e-mail: shannon.mathis@uah.edu doi: https://doi.org/10.33137/cpoj.v1i2.32040 introduction studies report that after lower-limb amputation, patients have high levels of pain in the form of chronic low back pain, residual limb pain, and phantom pain leading to restrictions in functional activity1. patients with high levels of pain and disability may develop avoidance behaviors. vlaeyen et al. presents the fear-avoidance model, which suggests that after an injury there are two pathways a patient will take based on their interpretation of acute pain 2. pain that is perceived as non-threatening leads to the patient’s recovery and return to normal activities of daily life. pain that is perceived as threatening, or pain catastrophizing, causes anxiety and induces mobility apprehension which leads to avoidance behaviors. avoidance behaviors may then lead to greater pain, depression, and disability3 . factors described in the literature that are related to mobility apprehension were measured in a sample of lower limb amputees. the purpose was to determine which of pain intensity, interference, and catastrophizing lead to increased mobility apprehension. methods subjects: amputee coalition conference attendees were recruited for participation (see table 1). apparatus: subjects completed the tampa scale for kinesiophobia (tsk) to measure mobility apprehension. the brief pain inventory (bpi) measures pain intensity which consists of a patient’s current, worst, least, and average pain. the pain interference subscale quantifies general activity, mood, walking ability, normal work, relations with other people, sleep, and enjoyment of life. the pain catastrophizing scale (pcs) measures the tendency to ruminate and magnify pain sensations. self-report instrument data are presented in table 2. data analysis: descriptive statistics were explored to present mean and standard deviations for all outcomes. a multivariable linear regression model included all variables of interest and results are presented in table 3. results mobility apprehension was the main variable of interest with a mean score of 34. this score is approaching the cut-off score of 39 representing a high level. half of the participants were questioned about recent falls and fear of falls. of the 31 respondents, 16 (52%) experienced a fall within the last year and 9 (29%) reported a fear of falls. discussion this data presents an attempt to determine factors associated with mobility apprehension among lower limb amputees. the findings were that pain catastrophizing was directly related to mobility apprehension. results indicate that a similar trial with a larger sample that is more representative of a wider cross-section of lowerlimb amputees is warranted. table 1. participant characteristics characteristic n (%) mean age (years, sd) 48.3 (14.8) sex • female • male 36 (68%) 17 (32%) race • white • non-white 43 (81%) 10 (19%) mean years since surgery (sd) 11.3 (13.5) mailto:shannon.mathis@uah.edu https://doi.org/10.33137/cpoj.v1i2.32040 mathis s.l. factors associated with mobility apprehension in amputees. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32040 2 open access abstract (oral presentation) aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 table 2. self-report instrument data characteristic m (sd) mobility apprehension high, ≥ 39 (n, %) low, < 39 (n, %) 34.2 (6.0) 10 (20%) 41 (80%) pain intensity 1.6 (1.7) high, ≥ 5 (n, %) 7 (13%) low, < 5 (n, %) 47 (87%) pain interference 2.5 (2.6) high, ≥ 5 (n, %) 13 (25%) low, < 5 (n, %) 40 (75%) pain catastrophizing 9.1 (10.0) high, ≥ 24 (n, %) 4 (8%) low, < 24 (n, %) 37 (92%) table 3. multivariable regression for factors associated with mobility apprehension characteristic β (p) pain intensity 0.25 (.48) pain interference -0.03 (.96) pain catastrophizing 0.31 (<.0001) conclusion pain catastrophizing was positively associated with mobility apprehension. significance results may assist clinicians by further understanding mobility apprehension and the fear-avoidance model. references 1. sinha et al. influence of adjustments to amputation and artificial limb on quality of life in patients following lower limb amputation. int j rehabil res. 2014, 1;37(1):74-9. doi:10.1097/mrr.0000000000000038 2. vlaeyen et al. fear of movement/(re)injury in chronic low back pain and its relation to behavioral performance. pain.1995; 62, 363-372. doi: 10.1016/0304-3959(94)00279n 3. archer et al. early postoperative fear of movement predicts pain, disability, and physical health six months after spinal surgery for degenerative conditions. spine j. 2014;14, 759767. doi:10.1016/j.spinee.2013.06.087 https://doi.org/10.1097/mrr.0000000000000038 https://doi.org/10.1016/j.spinee.2013.06.087 clemens s, gaunaurd i, lucarevic j, klute g, kirk-sanchez n, bennett c, gailey r.establishing the reliability and validity of the component timed-up-and-go test to determine basic prosthetic mobility in people with lower limb amputation. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32036 1 open access abstract (oral presentation) aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 establishing the reliability and validity of the component timedup-and-go test to determine basic prosthetic mobility in people with lower limb amputation sheila clemens*1,2, ignacio gaunaurd 1,2 ,jennifer lucarevic2, glenn klute3, neva kirk-sanchez2, christopher bennett4, robert gailey1,2 1 miami va healthcare system, miami, fl, usa. 2department of physical therapy, university of miami, coral gables, fl, usa. 3rehabilitation research and development, va puget sound health care system, seattle, wa,usa. 4music engineering technology program, university of miami, coral gables, fl, usa. * email: clemens.sheila@gmail.com doi: https://doi.org/10.33137/cpoj.v1i2.32036 introduction studies suggest that brief bouts of activity consisting of sit-to-stand transitions, gait initiation, turning and negotiation of obstacles, are essential tasks of daily mobility, as well as prosthetic mobility1,2. using outcome measures deemed reliable for use in the amputee population is ideal3,4. the purpose of this study was to investigate the reliability and validity of a component timed-up-and-go test (ctug), using a mobile application (app), to evaluate basic prosthetic mobility tasks in people with lower limb amputation (lla). the ctug captures time required to perform the subtask components of sit to stand transitions, linear gait, and a 180˚ turn that are requisites of the standard tug test. it was hypothesized that the ctug would demonstrate testretest reliability, differentiate between groups based on anatomical level of amputation, and exhibit convergent validity with other measures of prosthetic mobility and balance. methods subjects performed 4 trials of the ctug; turning twice toward and away from their prosthetic limb. the ctug was performed on top of a sensored gait mat to capture additional gait parameters. a total time to perform the test was recorded, as well as 5 component times: 1) sit to stand, 2) walk entering the turn, 3) 180 degree turn, 4) walk exiting the turn, 5) turn to sit. a custom mobile application was used to capture the time intervals. all data was recorded using an ipad air 2. results a convenience sample of 118 individuals with lla. all participants had non-vascular cause of unilateral lla at the transtibial (tta) or transfemoral (tfa) level, and were between 18-80 years old, ambulating a minimum of 8 m independently. groups were compared based on their level of amputation. the mean age of the cohort was 48.1 years, comprised of 54% males, with 53% having tfa. test-retest analyses resulted in an icc=.98 (f=.19; 95% ci .97, .99) for the total performance time, and iccs ranged from .71-.94 for each component time. moderate correlations existed between the ctug and plus-m (rs= -.56) suggesting convergent validity. significant differences existed between the tta and tfa groups (p<.05) for total time and each component time of the ctug suggesting known-groups validity. additionally, it was determined that people with tfa use different strategies to turn 180˚ compared to those with tta. table 1. known-groups validity of the ctug mailto:clemens.sheila@gmail.com https://doi.org/10.33137/cpoj.v1i2.32036 clemens s, gaunaurd i, lucarevic j, klute g, kirk-sanchez n, bennett c, gailey r.establishing the reliability and validity of the component timed-up-and-go test to determine basic prosthetic mobility in people with lower limb amputation. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32036 2 open access abstract (oral presentation) aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 conclusion the ctug is a reliable and valid measure of basic prosthetic mobility in community-dwelling people with lla. this study found differences between people with tfa as compared to tta in the ctug total time and all components times, confirming that basic prosthetic mobility skills vary between levels of amputation. significance an instrument for measurement of prosthetic mobility, the ctug, has been developed for use on people with lla. preliminary psychometric analyses indicate excellent reliability and validity for use in the amputee population, providing a powerful clinical tool. references 1. orendurff et al. how humans walk: bout duration, steps per bout, and rest duration. j rehabil res dev,2008; 45, 1077-89. doi: 10.1682/jrrd.2007.11.0197 2. bussman j, schrauwen hj, stam hj. daily physical activity and heart rate response in people with a unilateral traumatic transtibial amputation. arch phys med rehabil. 2008; 89, 4304. doi:10.1016/j.apmr.2007.11.012 3. resnik l, borgia m. reliability of outcome measures for people with lower-limb amputations: distinguishing true change from statistical error. phys ther. 2011; 91, 555-65. doi:10.2522/ptj.20100287 4. deathe et al. selection of outcome measures in lower extremity amputation rehabilitation: icf activities. disabil rehabil. 2009; 31, 1455-73. doi: 10.1080/09638280802639491 https://doi.org/10.1016/j.apmr.2007.11.012 https://doi.org/10.2522/ptj.20100287 https://doi.org/10.1080/09638280802639491 gholizadeh h, lemaire e.d, nielen d, lebel p. satisfaction and experience with the unity suspension system. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32030 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) satisfaction and experience with the unity suspension system hossein gholizadeh *1,2, edward d lemaire1,3, david nielen2, patrick lebel2 1ottawa hospital research institute, centre for rehabilitation research and development, ottawa, canada. 2prosthetics & orthotics, ottawa hospital rehabilitation centre, ottawa, canada. 3faculty of medicine, university of ottawa, canada. * email: gholizadeh87@yahoo.com background while elevated vacuum suspension systems have some benefits over the other suspension approaches 1–5, elevated vacuum may not be appropriate for all amputees. the unity sleeveless vacuum suspension system was developed to overcome issues related to knee range of motion and amputees comfort 6. this study compared the unity suspension system with suction and pin/lock systems based on user satisfaction and experience with these systems. methods twelve people with unilateral transtibial amputation were fitted with the ossur unity elevated vacuum suspension system, with 57.2 (sd=15.3) years mean age, 178.3 (sd=6.4) cm height, and 90.6 (sd=16.4) kg weight. participants completed the prosthesis evaluation questionnaire (peq) for their current prosthesis and again, following a minimum 4 week accommodation period, for the unity suspension system. results on average, participants required seven sessions (sd=2) for casting, gait training, socket adjustment, and troubleshooting before successful fitting. all participants mentioned no movement inside the socket and improved proprioception (i.e., feel where the prosthetic leg is in space) compared to their previous suspension system. after completed the study protocol, 75% of participants (nine people) preferred to continue with the elevated vacuum suspension system since they felt more comfortable walking. two people preferred their original pin/lock suspension system because they felt more freedom and comfort during kneeling and their job required kneeling most of the time. one participant preferred to continue with his original suction system (seal-in x5 and one way valve) because he felt more pressure around the seal area with seal-in v and elevated vacuum. all prosthesis evaluation questionnaire scores improved with unity suspension system (table 1). conclusion amputee satisfaction can be improved with the unity system compared to pin/lock and suction sockets. however, unity may not be appropriate for some amputees since there is less freedom and comfort during kneeling compared to pin/lock systems. in this study, a high functioning group with transtibial amputation (k3, k4) was recruited. the unity system’s effect on comfort for people with lower activity levels is still unclear. disclosure there is no conflict of interest in this study. acknowledgment the authors would like to thank knut lechler, nancy dudek, emily sinitski and kristleifur kristjansson for providing clinical and technical advice and support. this study was financially supported by mitacs and ossur. all prosthetics components were provided by ossur. references 1. board wj, street gm, caspers c. a comparison of transtibial amputee suction and vacuum socket conditions. prosthet orthot int. 2001;25(3):202–9. https://doi.org/10.1080/03093640108726603 table 1: prosthesis evaluation questionnaire scales validated scale subjects (old prosthesis) subject (unity) how many % improved ambulation (am) 64.9 81.2 25 appearance (ap) 69.2 81.7 18 frustration (fr) 57.2 75.0 31 perceived response (pr) 75.5 87.5 16 residual limb health (rl) 54.9 75.6 38 social burden (sb) 72.5 81.9 13 sounds (so) 61.3 69.9 14 utility (ut) 53.4 75.7 42 well being (wb) 60.0 77.8 30 doi: https://doi.org/10.33137/cpoj.v1i2.32030 https://doi.org/10.33137/cpoj.v1i2.32030 mailto:gholizadeh87@yahoo.com https://doi.org/10.1080/03093640108726603 https://doi.org/10.33137/cpoj.v1i2.32030 gholizadeh h, lemaire e.d, nielen d, lebel p. satisfaction and experience with the unity suspension system. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32030 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) 2. gholizadeh h, lemaire ed, eshraghi a. the evidence-base for elevated vacuum in lower limb prosthetics: literature review and professional feedback. clin biomech. 2016;37:108–16. https://doi.org/10.1016/j.clinbiomech.2016.06.005 3. arndt b, caldwell r, fatone s. use of a partial foot prosthesis with vacuum-assisted suspension: a case study. jpo j prosthet orthot. 2011;23(2):82–8. doi: 10.1097/jpo.0b013e318217e5f7 4. samitier et al. the benefits of using a vacuum-assisted socket system to improve balance and gait in elderly transtibial amputees. prosthet orthot int. 2014;40(1):83–8. https://doi.org/10.1177/0309364614546927 5. sanders et al. effects of elevated vacuum on in-socket residual limb fluid volume: case study results using bioimpedance analysis. j rehabil res dev. 2011;48(10):1231. doi:10.1682/jrrd.2010.11.0219 6. seal-in v catalog page [internet]. iceross seal-inv transtibial liner with wave. [online] available at https://assets.ossur.com/library/31253/iceross seal-in v catalog page.pdf. https://doi.org/10.33137/cpoj.v1i2.32030 https://doi.org/10.1016/j.clinbiomech.2016.06.005 doi:%2010.1097/jpo.0b013e318217e5f7 doi:%2010.1097/jpo.0b013e318217e5f7 https://doi.org/10.1177/0309364614546927 doi:10.1682/jrrd.2010.11.0219 https://assets.ossur.com/library/31253/iceross%20seal-in%20v%20catalog%20page.pdf https://assets.ossur.com/library/31253/iceross%20seal-in%20v%20catalog%20page.pdf campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of a 3d-printed transtibial socket. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32038 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) how infill percentage affects the ultimate strength of a 3dprinted transtibial socket leah campbell1, adriel lau*1, brittany pousett2, ernie janzen3, silvia u raschke3 1 prosthetics and orthotics, school of health sciences, british columbia institute of technology (bcit), burnaby, british columbia, canada. 2 barber prosthetics clinic, vancouver, british columbia, canada. 3 make + applied research, centre for applied research & innovation (cari), burnaby, british columbia, canada. * email: lau.adriel@gmail.com doi: https://doi.org/10.33137/cpoj.v1i2.32038 introduction 3d printing for non‐weight‐bearing upper extremity prostheses is becoming increasingly popular as a method of fabrication.1 some clinics in north america have begun using 3d printing to fabricate lower extremity diagnostic sockets (figure 1). the strength requirements for upper extremity prostheses are not as rigorous as the strength requirements for lower extremity prostheses. therefore, strength testing on 3d-printed lower extremity sockets is one of the first steps that needs to be conducted to ensure patient safety. 3d-printed prosthetic sockets are becoming an alternative option to traditional methods because it is possible to customize different parameters to create a strong structure. infill percentage is an important parameter to research as this can have an influence on the strength of 3d printed sockets.2 as both prosthetists and healthcare professionals, there is a need to become more involved in the process of designing and testing 3d printed sockets. the purpose of this study is to test how changing the infill percentage affects the ultimate strength of a 3d printed transtibial socket during initial contact. methods a total of nine transtibial sockets were printed using a fused deposition modeling (fdm) printer. three different infill percentages were chosen because they represent realistic percentages that clinicians may decide to print. three sockets were printed at 30% infill, three sockets at 40% infill and three sockets at 50% infill. all the sockets were printed from a white polylactic acid (pla) filament and from the same data file to maintain shape consistency (table 1). the sockets were tested for ultimate strength in a tinius olsen universal testing machine (figure 2) located at the british columbia institute of technology. the international organization for standardization (iso) standard 10328 outlines the process and procedures of structural testing in lower limb prostheses.3 the standard determines whether the sockets can withstand the minimum static load at initial contact and how much additional load it can withstand. table 1. characteristics of the 3d-printed sockets before structural tests. results in all nine sockets, the amount of force that resulted in socket failure exceeded the iso 10328 threshold of 4480n (figure 3). the infill percentages (30% 50%) do not appear to impact the ultimate strength of the socket. observational analysis of socket failure show that all sockets broke in two areas: 1) lateral mid socket or 2) medial popliteal area with the latter region being the most common. figure 1. 3d printed transtibial socket figure 2. testing jig with socket. https://doi.org/10.33137/cpoj.v1i2.32038 mailto:lau.adriel@gmail.com https://doi.org/10.33137/cpoj.v1i2.32038 campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of a 3d-printed transtibial socket. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32038 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) figure 3. force of failure of 3d printed transtibial sockets. horizontal line represents the strength threshold set by iso standard 10328 (4480n). table 2. areas of socket failure and failure types conclusion 3d printing technology is currently being used in many different industries. the field of prosthetics and orthotics needs to demonstrate how it can successfully use the technology in clinical practice. a logical first step is testing the strength of 3d-printed prosthetic sockets to determine if it is safe for patient use. using the specific criteria (static testing, initial contact and p5 weight class) and procedures of iso standard 10328, this research project demonstrated that the ultimate strength of the 3dprinted sockets exceeded the minimum required 4480n threshold set by the standard. furthermore, infill percentages ranging from 30% to 50% did not seem to affect the ultimate strength of the sockets. future directions this project focused on specific conditions whereas the standard outlines additional conditions.3 it is important that these other conditions are tested to fully deem a 3d printed socket safe for patient use. 3d printing technology is advancing quickly. it would be beneficial to investigate how different printers, materials, and methods of printing can affect the strength of a socket. further research should test multiple parameters (e.g. layer height and wall thickness) to see their combined effect on the strength of a prosthetic socket. this project is a small part of a much larger research initiative involving collaboration among clinicians and technicians. the hope is that the findings from this project contribute to the understanding and awareness of 3d printing in the prosthetics and orthotics field. references 1. chhaya m.p, poh p.s, balmayor e.r, griensven m, schantz j.t, hutmacher d.w. additive manufacturing in biomedical sciences and the need for definitions and norms. expert review of medical devices. 2015; 12(5), 537–543. doi:10.1586/17434440.2015.1059274 2. johansson f. optimizing fused filament fabrication 3d printing for durability: tensile properties and layer bonding (dissertation). 2016; retrieved from: http://urn.kb.se/resolve?urn=urn:nbn:se:bth-12355 3.international organization for standardization. (2006). prosthetics structural testing of lower limb prostheses requirements and test methods (iso 10328). acknowledgment barber prosthetics clinic • dave moe, cp(c) • daryl murphy, rtp(c) • brittany pousett, m.sc., cp(c) • malena rapaport, m.sc., cp(c) additive o&p ernie janzen, lab coordinator lynn erickson, ph.d., p.eng. nathan devos, ph.d. caroline soo, m.sc. figure 4. socket broken in the medial popliteal area. figure 5. socket broken in the middle lateral area. https://doi.org/10.33137/cpoj.v1i2.32038 http://urn.kb.se/resolve?urn=urn:nbn:se:bth-12355 popovic i, cutti a, ryan t, schaefer m, andres e, wuestefeld d, winkler c, baun k, bischof b, braatz f, miguelez j, conyers d, hahn a. do multi-grip hands increase function and patient satisfaction when compared to traditional myoelectric hands? canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32049 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) do multi-grip hands increase function and patient satisfaction when compared to traditional myoelectric hands? ivana popovic1, andrea cutti2, tiffany ryan3, michael schaefer4, erik andres1, daniela wuestefeld1, claudia winkler4, kerstin baun3, birgit bischof1, frank braatz5, john miguelez3, dan conyers3, andreas hahn1* 1otto bock healthcare otto bock, germany. 2 centro protesi inai, italy. 3 advanced arm dynamics, usa. 4 pohlig gmbh, germany. 5 medical university of gottingen, germany. * e-mail: andreas.hahn@ottobock.com doi: https://doi.org/10.33137/cpoj.v1i2.32049 introduction myoelectric hands progressed from single grip hands (traditional myoelectric devices (th)) to be multi-grip hands (mgh) which are hypothesized to bring more degrees of freedom, greater range of motion and improved grasping capabilities1,2. their impact on patients’ lives has been documented in only a few case studies. the strategic consortium for upper limb prosthetic technologies (sculpt) aims to assess the potential benefits mgh with respect to function and patient satisfaction compared to th systems. methods transradial upper limb amputees currently fitted with variplus hand, sensor hand speed, michelangelo hand (mh), i-limb hand (lh), bebionic hand (bh), or vincent hand (vh) have been enrolled. after informed consent, participants completed a survey either online, during telephone interview, or in person. the survey comprises self-reported outcome measures: (1) trinity amputation prosthesis experience scales (tapes); (2) disabilities of the arm, shoulder, and hand (dash); (3) euro quality of life questionnaire (eq-5d); and (4) sculpt questionnaire. the sculpt questionnaire addresses (a) general assessment, (b) usage of prosthetic hand, (c) prosthetic hand selection, (d) functionality of prosthetic hand, (e) therapy and training, (f) service and failure of the prosthetic hand, and (g) change of the prosthetic hand. results data for 124 users were analyzed. users were mainly male (78%), median age 38ys (range 18-65ys), 72% had acquired amputation. 48% were th users, while 52% were fitted with mgh (27% mh, 13% lh, 11% bh, 1% vh). mgh showed superiority over th in sculpt hand selection (p<0.001) and hand functionality scores (p<0.001) (figure 1). mgh were appreciated for their aesthetic appearance, flexible wrist, and functionality of different grip patterns. sculpt hand selection and hand functionality scores showed weak positive correlations with all tapes sub-scores (p<0.01). no statistical significant difference was observed in tapes, dash, and eq-5d. stratification revealed advantages of mh, bh and th over lh in dash core (p<0.05), tapes optimal adjustment sub-score (p<0.05), qaly (p<0.01) and phantom limb pain (mh vs lh, p<0.05; bh vs lh, p=0.01, th vs lh p<0.01). mh and bh were worn most with average wearing time of 12 h/day (lh 8h/day, p<0.05). users of bh hand reported highest adjustment to limitation (p<0.05) and satisfaction (p<0.05). bh was most appreciated for its appearance (p<0.05). in comparison to mh and th users gave advantage to bh´s color and shape. figure 1. sculpt hand selection and hand functionality scores for mgh and th (*** p<0.001) https://doi.org/10.33137/cpoj.v1i2.32049 mailto:andreas.hahn@ottobock.com https://doi.org/10.33137/cpoj.v1i2.32049 popovic i, cutti a, ryan t, schaefer m, andres e, wuestefeld d, winkler c, baun k, bischof b, braatz f, miguelez j, conyers d, hahn a. do multi-grip hands increase function and patient satisfaction when compared to traditional myoelectric hands? canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32049 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) in everyday life activities bh and mh were preferable for hobby activities, bh for activities such as opening a door, washing, and carrying a bag or briefcase, mh for doing heavy household chores and cutting activities. compared to users initially fitted with the mgh and having exclusive experience with mgh, users who experienced both, th and mgh, report significantly increased wearing time of their current mgh (p<0.05), hand functionality (measured via dash, p<0.05), and quality of life (qaly, p<0.05). conclusion compared to th, mgh bring additional value to users with respect to aesthetic appearance, flexible wrist options, and functionality of different grip patterns. still, neither mgh matches a “perfect hand” leaving substantial margin for improvement. performance based tests as well as cross over studies are suggested to better evaluate the differences between th and mgh. significance one of the largest surveys on exoskeletal myoelectric hand prosthetics allow insights on the relevant differences between single and multi-grip devices. references 1.belter jt, et al. mechanical design and performance specifications of anthropomorphic prosthetic hands: a review. j rehabil res dev. 2013;50(5):599-618. http://dx.doi.org/10.1682/jrrd.2011.10.0188 2.vergara m et al. an introductory study of common grasps used by adults during performance of activities of daily living. j hand ther. 2014;27(3):225-33. doi: 10.1016/j.jht.2014.04. 002. disclosure sculpt combines the experience of physicians, engineers, therapists, clinicians, and certified prosthetists. sculpt members are: advanced arm dynamics usa; centro protesi inail, italy; pohlig gmbh, germany; otto bock healthcare. https://doi.org/10.33137/cpoj.v1i2.32049 mcgrath m, stech n, laszczak p, kercher a, zahedi s, moser d. how reproducible are the effects of a microprocessor foot? canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32013 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) how reproducible are the effects of a microprocessor foot? michael mcgrath*1, nadine stech1, piotr laszczak1, alan kercher2, saeed zahedi1, david moser1 1endolite technology centre, basingstoke, uk 2endolite north america, miamisburg, oh, usa *email: mike.mcgrath@blatchford.co.uk doi: https://doi.org/10.33137/cpoj.v1i2.32013 introduction using microprocessor-control to dynamically adapt hydraulic ankles, by changing the resistances to dorsiflexion and plantarflexion (df/pf) movements, has been shown to have beneficial biomechanical effects during slope descent1. another, more recent case study also showed that the level walking biomechanical effects of microprocessor-feet (mpf) persist, and the same trends can be observed in repeated gait analysis sessions, over a year apart2. this work looks to expand on both of these concepts, analysing repeated gait analysis sessions to see if the biomechanical changes of mpf during slope descent are reproducible over time. methods a mixed cohort of trans-tibial and trans-femoral, k3 amputees participated in this study. each was fitted with a microprocessor-controlled hydraulic ankle-foot (elan, endolite), which dynamically varies the resistances to dorsi-/plantarflexion (df/pf) depending on the gradient of the walking surface. two prosthetic conditions were tested, in a randomised order. these included one with the dynamic resistance variation active (mpf-on) and one without (mpf-off), so that the device behaved like a regular hydraulic ankle, with constant resistance to df/pf. each participant was asked to descend a 5° slope at their comfortable walking speed. a 5° slope was selected as this aligns with the ada regulations regarding disability access ramps – a common real-life environmental barrier. kinematic and kinetic measurements were recorded using a gait analysis system and a force plate embedded in the sloped surface. each participant was recorded for two different data collection sessions, at least a month apart. results the findings showed a number of gait parameter changes that were reproduced in the different testing sessions. while quantitative changes were different, even within participants, the observable changes were in the same direction each time. the most consistent changes occurred at the prosthetic ‘ankle’. the transition from df moment to pf moment at the prosthetic ‘ankle’ consistently occurred earlier in the gait cycle with the mpf-on. this implied that there was less resistance to pf movement, so a stable ‘foot flat’ position was achieved sooner and so did the change from ‘heel rocker’ to ‘ankle rocker’. the earlier transition meant that there was an increased resistance to df movement, implying a braking effect to control momentum build up. this effect was also seen as increased negative ‘ankle’ work done. these same trends were observed for both trans-tibial and trans-femoral amputees, showing reproducibility regardless of amputation level. figure 1: the prosthetic ‘ankle’ moment plots for a trans-tibial amputee with mpf-off (black) and mpf-on (green), for test sessions four months apart. conclusion it is not simply the function of a prosthetic device that is important but also the consistency of that function. a mailto:mike.mcgrath@blatchford.co.uk https://doi.org/10.33137/cpoj.v1i2.32013 mcgrath m, stech n, laszczak p, kercher a, zahedi s, moser d. how reproducible are the effects of a microprocessor foot? canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32013 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) consistent performance will improve user confidence in a prosthetic device and highlights the potential to influence long term health problems, such as osteoarthritis and back pain, both of which are common among the amputee population3. significance showing reproducibility of the effects of mpfs indicates that there will be an influence on the long term biomechanics of the user. references 1.struchkov et al. biomechanics of ramp descent in unilateral trans-tibial amputees: comparison of a microprocessor controlled foot with conventional ankle-foot mechanisms. clin biomech. 2016;32:164–170. doi: 10.1016/j.clinbiomech.2015.11.015 2.de asha et al. which prosthetic foot to prescribe?: biomechanical differences found during a single-session comparison of different foot types hold true 1 year later. j prosthet orthot. 2017;29(1):39–43. doi:10.1097/jpo.0000000000000119 3.gailey. review of secondary physical conditions associated with lower-limb amputation and long-term prosthesis use. j rehabil res dev. 2008;45(1):15-29. doi: 10.1682/jrrd.2006.11.0147 disclosure the authors are employees of endolite north america or blatchford (the parent company of endolite north america); the manufacturer of the ankle-foot devices used in this study. https://doi.org/10.1016/j.clinbiomech.2015.11.015 tomkin m, gholizadeh h, sinitski e, lemaire e.d. transtibial amputee gait with the pro-flex foot during level, decline, and incline walking. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018 . https://doi.org/10.33137/cpoj.v1i2.32003 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) transtibial amputee gait with the pro-flex foot during level, decline, and incline walking matthew tomkin1,2*, hossein gholizadeh1,3, emily sinitski1,4, edward d lemaire1,5 1ottawa hospital research institute, centre for rehabilitation research and development, canada. 2ottawa-carleton institute for biomedical engineering, university of ottawa, canada. 3prosthetics & orthotics, the ottawa hospital rehabilitation centre, canada. 4canadian forces health services, canada. 5faculty of medicine, university of ottawa, canada. * email: mtomk062@uottawa.ca introduction the össur pro-flex is a 3-blade carbon fiber prosthetic foot designed to provide greater ankle range of motion compared to conventional energy storing and returning prosthetic feet1,2. to provide knowledge on pro-flex biomechanical performance, kinematic and kinetic gait parameters were evaluated and compared with the össur pro-flex xc prosthetic foot. outcomes from this study provide clinical professionals with important decision-making knowledge about two innovative energy storing and returning prosthetic feet. methods three k3 unilateral transtibial amputees were fitted with the pro-flex and the össur unity vacuum suspension system. all participants were previously fitted with the pro-flex xc and unity system. participants completed a warm-up trial and multiple self-paced walking trials in a virtual park (caren-extended virtual reality system)3. 3d motion was evaluated on level, 7° decline, and 7° incline walking conditions. results pro-flex ankle range of motion increased compared to the pro-flex xc during all conditions. ankle push-off power was greater with the pro-flex xc during level and incline walking; however, similar power was observed during decline walking. table 1. mean and standard deviation for ankle range of motion (°). table 2. mean and standard deviation for ankle push-off power (w/kg). conclusion pro-flex ankle range of motion was greater than pro-flex xc; however, pro-flex range of motion was smaller than reported by heitzmann et al.1, perhaps due to differences in methodologies and study populations (e.g., heitzmann had k3 and k4 participants). as expected, pro-flex peak ankle power generation did not surpass pro-flex xc during any of the conditions, since pro-flex xc was designed to generate appropriate power over a larger variety of activities and impact levels compared to proflex4. significance pro-flex provided greater ankle range of motion during level and slope self-paced walking, which may reduce compensatory gait strategies on sloped surfaces. however, the k3 participants may not have taken full advantage of pro-flex’s ankle range of motion potential. while push-off powers were similar between feet, pro-flex xc was designed for higher activity and achieved greater energy return. further research is required to identify when people benefit from greater ankle range of motion while maintaining ankle push-off power. future studies with high activity transtibial and transfemoral amputees will provide a broader understanding about pro-flex’s biomechanical performance. doi: https://doi.org/10.33137/cpoj.v1i2.32003 https://doi.org/10.33137/cpoj.v1i2.32003 mailto:mtomk062@uottawa.ca https://doi.org/10.33137/cpoj.v1i2.32003 tomkin m, gholizadeh h, sinitski e, lemaire e.d. transtibial amputee gait with the pro-flex foot during level, decline, and incline walking. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018 . https://doi.org/10.33137/cpoj.v1i2.32003 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) figure 1. mean prosthetic ankle angle and power during level, decline, and incline walking. pro-flex standard deviation in gray. acknowledge this study was financially supported by mitacs and prosthetic components were provided by össur. courtney bridgewater and andrew smith are acknowledged for their assistance with motion capture and data processing. references 1. heitzmann, daniel ww, et al. "benefits of an increased prosthetic ankle range of motion for individuals with a transtibial amputation walking with a new prosthetic foot." gait & posture, 64, 174-180, 2018. https://doi.org/10.1016/j.gaitpost.2018.06.022 2. össur [internet]. c2018 [cited 2018 aug 14]. pro-flex. available from: https://www.ossur.com/prostheticsolutions/ products/dynamic-solutions/pro-flex. 3. e. h. sinitski, e. d. lemaire, and n. baddour, “evaluation of motion platform embedded with force plate-instrumented treadmill.” j. rehabil. res. dev., 52(2), 221–233, 2015. doi: 10.1682/jrrd.2013.11.0244. 4. össur [internet]. c2018 [cited 2018 aug 14]. pro-flex xc. available from: https://www.ossur.com/prosthetic-solutions/ products/ dynamic-solutions/pro-flex-xc. https://doi.org/10.33137/cpoj.v1i2.32003 https://doi.org/10.1016/j.gaitpost.2018.06.022 doi:%2010.1682/jrrd.2013.11.0244. doi:%2010.1682/jrrd.2013.11.0244. smith m. what in the “heel” do they feel? 15303. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32044 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) what in the “heel” do they feel? 15303 megan smith, surestep, south bend indiana, usa. email: megans@surestep.net doi: https://doi.org/10.33137/cpoj.v1i2.32044 introduction a typical gait pattern includes a heel strike, followed by a smooth transition to foot flat through loading response. children with poor postural control and related gait deficits often present with anterior weight lines, which result in loss of first rocker and/or a fast transition from initial contact to foot flat. the foot has many important jobs, including providing proprioceptive feedback. there are 104 cutaneous mechanoreceptors on the plantar surface of the foot.1 while most of the sensors are in the metatarsal/tarsal and toe regions, we cannot forget the role of the mechanoreceptors in the heel. figure 1. location of mechanoreceptors in the foot standard orthotic designs typically encompass the heel with plastic. this may accelerate 1st rocker and result in more inclined tibia during midstance. this design can also reduce typical sensory input a child receives through his or her heels. when providing orthotic solutions, we should consider the patient’s postural control and weight lines as well as ensure we are not hindering the foot’s natural ability to “feel” and provide feedback to the rest of the body. the ability to feel changes in terrain to adjust and build a repertoire of motor and postural strategies is a vital part of typical development.2,3 a new modification, the open heel, was designed and evaluated for function. the hypothesis was that the open heel modification would restore 1st rocker timing by slowing the transition from initial contact to foot flat, slow down overall gait velocity and increase integrated pressure. methods 11 children (4.4 ± 1.8 years old) were included in this retrospective study. each participant presented with anterior weight lines and poor postural control. primary diagnoses included down syndrome, autism and toe walking. each was fit with an orthosis with an open heel modification. four patients (group 1) had also previously been fit with the same orthosis (i.e. smo or afo) with a standard heel post and had direct comparison data with the open heel modification. seven patients (group 2) were fit only with an orthosis with the open heel modification. (a) (b) figure 2. (a) open heel modification and (b) standard heel post design4. data from the zeno walkway and protokinetics software5 was analyzed to assess changes in velocity, integrated pressure and time from initial contact to footflat (ic – ff). for time to footflat, 4 right footfalls were analyzed. results group 1: data from the standard heel post (hp) design and open heel (oh) modification were compared. secondly, data from the oh modification and barefoot (bf) were compared for reference for group 2 data. data is reported as percent change between conditions. velocity decreased and integrated pressure and ic-ff time increased in both comparisons. group 2: percent changes from the oh modification and bf were calculated and compared to group 1 data. velocity decreased and integrated pressure and ic-ff time increased. changes in group 2 were similar to changes in group 1 (oh:bf). table 1. percent changes in data for group 1 and group 2 group 1 group 2 oh:hp % change (sd) oh:bf % change (sd) oh:bf % change (sd) velocity -19% (0.14) -10% (0.26) -7% (0.16) integrated pressure 25% (0.16) 29% (0.19) 37% (0.27) ic – ff 26% (0.24) 103% (0.54) 84% (0.47) mailto:megans@surestep.net https://doi.org/10.33137/cpoj.v1i2.32044 smith m. what in the “heel” do they feel? 15303. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32044 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) discussion when children have anterior weight lines, velocity tends to be increased – they are essentially falling down with each step. in order to work on postural control, slowing down is important. the comparison of the open heel data to barefoot of the children in group 1 and group 2 were very similar. this suggests that the oh modification in their orthoses had positive changes compared to barefoot and heel post designs. the open heel modification dampens the ground reaction forces at initial contact and slows 1st rocker compared to orthoses with a heel post and barefoot conditions. the increase in amount of pressure over the time spent in stance suggests that the participants put more pressure through the orthosis and may be feeling more input back from the ground. the open heel modification should be considered for patients with sensory deficits and/or anterior weight lines. references 1. kennedy pm, inglis jt. distribution and behavior of glabrous cutaneous receptors in the human foot sole. j physiol. 2002; 538(pt 3): 995-1002. doi: 10.1113/jphysiol.2001.013087 2. dusing sc, harbourne rt. variability in postural control during infancy: implications for development, assessment, and intervention. phys ther. 2010; 90:1838-1849. doi:10.2522/ptj.2010033 3. fetters l. perspective on variability in the development of human action. phys ther. 2010; 90:1860-1867. doi:10.2522/ptj.2010090 4. surestep products. www.surestep.net 5.protokinetics software and zeno walkway. www.protokinetics.com https://dx.doi.org/10.1113%2fjphysiol.2001.013087 https://doi.org/10.2522/ptj.2010033 https://doi.org/10.2522/ptj.2010090 altenburg b, ernst m, schmalz t. an innovative foot module with easily accessible frontal plane adaptation enhances the locomotion on uneven ground. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32029 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) an innovative foot module with easily accessible frontal plane adaptation enhances the locomotion on uneven ground björn altenburg*, michael ernst, thomas schmalz ottobock healthcare gmbh, germany. * email: bjoern.altenburg@ottobock.com doi: https://doi.org/10.33137/cpoj.v1i2.32029 introduction real-life outdoor walking of amputees is challenged by uneven ground. uneven ground requires either a component adaptation in the sagittal plane or in frontal plane or both. the lack of adaptability of prosthetic components requires compensational movement strategies by the user. common energy storing and returning (esr) feet have some basic flexibility through the carbon structure allowing for some limited adaptation in both planes. for the frontal plane the split toe feature adds some functionality. however, even with split toe the rom is clearly limited and needs high force impact for minor adaptations. now there is a novel foot module allowing for 10° inversion/eversion through a dedicated joint. this study investigates the hypothesis that such a foot module with easily accessible frontal plane adaptation enhances the locomotion on uneven ground. methods 12 unilateral tt amputees with activity level k3 or higher participated in this study. in addition the data of 10 able-bodied was captured. for the measurements a stationary gait analysis system with 12 vicon bonita cameras and 2 kistler force plates was used. a dedicated marker set was applied that enables the observer to distinguish frontal plane adaptations of the foot between joint adaptation, carbon base deformation and shoe/footshell deformation. observed situations: walking on level ground, walking on a 5° cross slope, walking on a 10° cross slope (all at self-selected walking speed, ), standing on level ground, standing on a 5° cross slope, standing on a 10° cross slope. all cross slopes were connected to the kistler force plates. the participants completed the measurement tracks 3 times with 3 setups: their everyday foot (individual esr), the novel foot module, a reference esr (triton lp, ottobock or proflex lp, össur). the accommodation time to the different feet was minimum 4 weeks each. the order of setups and type of reference esr was randomized. next to the biomechanical measurements the participants walked an indoor course (gravel, obstacles, cross slopes, tight turns) and completed questionnaires with respect to socket comfort, safety and overall satisfaction during the indoor course and their >4 weeks daily use of the components. results for the carbon structure of the novel foot module an early and nearly full adaptation to the cross slope at the beginning of mid stance was measured. the reference esr feet showed significant (p<0,05) less adaptation with maxima at the end of terminal stance. the cop path of the novel foot clearly shows a more physiological pattern (referring to measurements of the sound side and control group) compared to the esr feet. the measured external knee adduction moment (eam) at the 10° valley condition was significantly reduced with the novel foot module. the questionnaires report significantly higher ratings for perceived safety and socket comfort using the novel foot module compared to the reference esr foot used in the study. eight out of twelve tt users preferred the novel foot module over the reference esrs for their daily routine. conclusion the study results confirm benefits of the novel foot module when ambulating on cross slopes as one condition of uneven ground. especially for tt amputees it is crucial to minimize recurring improper frontal knee loads on the affected side. such component functionality contributes to minimize frontal knee loads. due to the faster and more comprehensive adaptation to the cross slope condition, less compensation is required and users feel more safe and comfortable when ambulating on uneven ground using the novel foot module. significance few authors have investigated lower limb amputee gait on cross slopes1,2,3,4,5 with main focus on kinematics and compensational strategies during swing phase. this doi:%20https://doi.org/10.33137/cpoj.v1i2.32029 mailto:bjoern.altenburg@ottobock.com https://doi.org/10.33137/cpoj.v1i2.32029 altenburg b, ernst m, schmalz t. an innovative foot module with easily accessible frontal plane adaptation enhances the locomotion on uneven ground. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32029 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) study focuses on stance phase. in addition it’s the first study comparing different foot components on cross slopes and thus makes a valuable contribution to the literature of lower limb amputee’s gait. references 1. starholm im et al. energy expenditure of transfemoral amputees walking on a horizontal and tilted treadmill simulating different outdoor walking conditions. prosthet orthot int; 2010; 34; 184-94. doi: 10.3109/03093640903585016 2. hak i et al. walking in an unstable environment: strategies used by transtibial amputees to prevent falling during gait. arch phys med rehabil; 2013; 94; 2186-93. doi: 10.1016/j.apmr.2013.07.020 3. villa c et al. evolution of vaulting strategy during locomotion of individuals with transfemoral amputation on slopes and cross-slopes compared to level walking. clin biomech; 2015; 30; 623-8. doi: 10.1016/j.clinbiomech.2015.03.022 4. sinitski eh et al. fixed and self-paced treadmill walking for able-bodied and transtibial amputees in a multi-terrain virtual environment. gait posture; 2015; 41; 568-73. doi: 10.1016/j.gaitpost.2014.12.016 5. villa c et al. cross-slope and level walking strategies during swing in individuals with lower limb amputation. arch phys med rehabil; 2017; 98; 1149-57. doi: 10.1016/j.apmr.2016.10.007 disclosure authors are full time employees of the ottobock se & co. kgaa. doi:%20https://doi.org/10.33137/cpoj.v1i2.32029 https://doi.org/10.3109/03093640903585016 https://doi.org/10.1016/j.apmr.2013.07.020 https://doi.org/10.1016/j.clinbiomech.2015.03.022 https://doi.org/10.1016/j.gaitpost.2014.12.016 https://doi.org/10.1016/j.apmr.2016.10.007 raschke s.u. transformation, revolution, evolution: provocative times for prosthetics & orthotics. canadian prosthetics & orthotics journal. volume1, issue1, no 1, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30000 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x volume 1, issue 1 2 0 1 8 editorial issn: 2561-987x https://doi.org/10.33137/cpoj.v1i1.30000 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com raschke s.u. transformation, revolution, evolution: provocative times for prosthetics & orthotics. canadian prosthetics & orthotics journal. volume1, issue1, no 1, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30000 1 open access provocative times for prosthetics & orthotics volume 1, issue 1, article no. 1, july 2018 editorial doi: https://doi.org/10.33137/cpoj.v1i1.30000 transformation, revolution, evolution: provocative times for prosthetics & orthotics silvia ursula raschke, co-editor-in-chief marshall mcluhan: “obsolescence never meant the end of anything, it’s just the beginning” are we crazy? the launch of a new journal, the canadian prosthetics and orthotics journal (cpoj), is a good time to consider the brilliance – or foolhardiness – of such a venture as well-established peer-review journals struggle to survive. the challenges faced by the traditional, print based, peer-review publishing model are rooted in a greater wave of rapid disruptive change influencing technology innovation models and economic models in a wide range of sectors, including health care across the clinical care delivery continuum. how will this change influence prosthetics and orthotics and what does it mean for the future? these are important questions to consider, as cpoj charts a course aiming to respond to these trends in a positive, sustainable way while adhering to high professional and academic standards. finding answers starts with a short reflection on the causes of this change: the threads weaving the fabric of the fourth industrial revolution. the fourth industrial revolution with its origins in the mid last century, the fourth industrial revolution is now well and truly upon us. characterized by the convergence of the digital, physical and biological domains, fresh approaches and markets are being created at intersections between two or all three of these domains.1 the space occupied by prosthetics and orthotics is not being spared. this most recent industrial revolution is being built on a foundation of vast databases that are created, managed and mined using newly developed data collection, machine learning and communication tools. lord kelvin (1824-1907) said: “if you can not measure it, you can not improve it.” with the vast number of data driven tools now available the ability to improve and transform, across all sectors and fields, has become substantial and within reach. ready or not – change is coming. early examples of this revolution’s effects can be found in manufacturing (digital supply chains, robotics), commerce (web-based business models, block chain) and communication (changing models of journalism, social media). academic research is also evolving, as the traditional peer review model is no longer the sole method for driving scientific knowledge development and dissemination. in prosthetics and orthotics, the first innovation cycle includes 3d printed prosthetic legs and customized foot orthotics incorporated into web-based business models. future directions will likely include smart prostheses and orthoses and mass customized devices. at the broadest level of science and discovery, the spirit of the fourth industrial revolution demystifies and democratizes knowledge, engaging and empowering non-traditional participants who are not afraid to challenge the status quo. (e.g. citizen science and maker movements).2,3 time honoured models of knowledge transfer, primarily via journals and conferences, are being supplemented by engaging, accessible models such as ted talks,4 which reach vast, international audiences in seconds. more creative, flexible formats and portals for peerreview level research, such as open access models, video journals and publication of research protocols without results are emerging, but in future will only be one part of a massive knowledge stream within what has become a very wide and colourful information pipeline. emerging from the pipeline are a new class of thought leaders who challenge the traditional ‘expert model’ where academics and professionals worked their way up an established hierarchy or credentialing process. the days of the unchallenged ‘expert’ are gone.5 modalities such as social media, the internet and personal monitoring and https://doi.org/10.33137/cpoj.v1i1.30000 https://doi.org/10.33137/cpoj.v1i1.30000 http://online-publication.com/ojs/index.php/cpoj/navigationmenu/view/editorsinchief raschke s.u. transformation, revolution, evolution: provocative times for prosthetics & orthotics. canadian prosthetics & orthotics journal. volume1, issue1, no 1, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30000 2 open access provocative times for prosthetics & orthotics volume 1, issue 1, article no. 1, july 2018 communication devices allow a wide range of solution providers from anywhere to have direct access to those seeking solutions without necessarily engaging members of the traditional hierarchy. the winds of change canadian visionary marshall mcluhan said “obsolescence never meant the end of anything, it’s just the beginning”. this axiom is taken for granted by those who embrace change, typically in data driven sectors such a business or engineering. these sectors tend to be early adopters of new ideas and technology while sectors such as health care traditionally lag behind in with the adoption of new technology and processes.6 whichever approach taken, enthusiastic early adopter or reluctant laggard, the innovation life cycle does not stop and is accelerating at a faster pace than seen in the previous industrial revolutions.7 this paradigm shift is rapidly changing the terrain in all sectors, at the technical, societal and policy levels. interestingly, a very commonly cited example of the positive effects the fourth industrial revolution will have on society is the prosthetics and orthotics sector. prosthetic and orthotic examples provide a real, highly visual, easy to understand example of innovation potential at the convergence of the digital, physical and biological realms, alongside a compelling story of the power to radically transform and improve on existing approaches – more efficiently and at a lower cost. while the focus in the fourth industrial revolution is innovative technology, it must not be overlooked that all of this is predicated on the ability to provide more for less. whatever the grand vision presented, the primary drivers are increasingly fiscal and can never be discounted or overlooked. cpoj’s goal in the spirit of the fourth industrial revolution, the canadian prosthetics and orthotics journal will strive to be an interdisciplinary, multi-modal information hub linking the digital, physical and biological realms as they relate to prosthetics and orthotics. cpoj is committed to providing free open access to high quality papers, reviewed by an interdisciplinary editorial board that includes persons from the clinical practice of prosthetics and orthotics. in addition, cpoj aims to provide good quality information across the information pipeline, by also providing portals for technical papers, case studies, theses, poster presentations and videos in the open access format. the goal is to support innovation and the advancement of the state of practice prosthetics and orthotics by all persons committed to making positive contributions and providing the best outcomes for our constituent communities. the pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails. william arthur ward (1921-1994) as co-editor in chief, i wish you happy and challenging reading. silvia ursula raschke, phd co-editor-in-chief, project leader, bcit make+, principle investigator, create, british columbia institute of technology (bcit), 3700 willingdon avenue, burnaby, british columbia, canada, v5g 3h2 e-mail: silvia_raschke@bcit.ca references 1. fourth industrial revolution. [online]; available at: https://www.weforum.org/focus/fourth-industrialrevolution. accessed july 9, 2018. 2. what is citizen science? [online]; available at: http://www.citizensciencecenter.com/citizen-sciencedefinition/. accessed july 9, 2018. 3. hatch m. the maker movement manifesto: rules for innovation in the new world of crafters, hackers and tinkers. mcgraw-hill education, sept 2013. 4. ted, ideas worth spreading. [online]; available at: https://www.ted.com/about/our-organization. accessed july 9, 2018. 5. maasen s, weingart p. what's new in scientific advice to politics? introductory essay. in: maasen and weingart (eds) democratization of expertise? exploring novel forms of scientific advice in political decision-making, 2005; pp 1-20. springer. 6. herzlinger re. why innovation in health care is so hard. harvard business review. 2006; 84(5):58-66, 156. 7. schwab k. the fourth industrial revolution: what it means, how to respond. world economic forum. [online]; available at: https://www.weforum.org/agenda/2016/01/the-fourthindustrial-revolution-what-it-means-and-how-torespond/. accessed july 10, 2018. https://doi.org/10.33137/cpoj.v1i1.30000 mailto:silvia_raschke@bcit.ca https://www.weforum.org/focus/fourth-industrial-revolution https://www.weforum.org/focus/fourth-industrial-revolution http://www.citizensciencecenter.com/citizen-science-definition/ http://www.citizensciencecenter.com/citizen-science-definition/ https://www.ted.com/about/our-organization. https://www.weforum.org/agenda/2016/01/the-fourth-industrial-revolution-what-it-means-and-how-to-respond/ https://www.weforum.org/agenda/2016/01/the-fourth-industrial-revolution-what-it-means-and-how-to-respond/ https://www.weforum.org/agenda/2016/01/the-fourth-industrial-revolution-what-it-means-and-how-to-respond/ raschke s.u. transformation, revolution, evolution: provocative times for prosthetics & orthotics. canadian prosthetics & orthotics journal. volume1, issue1, no 1, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30000 3 open access provocative times for prosthetics & orthotics volume 1, issue 1, article no. 1, july 2018 short scientific biography dr. silvia raschke has a phd in prosthetics and orthotics from strathclyde university’s faculty of engineering (1997). dr. raschke is a research faculty member at the british columbia institute of technology. her research gives voice to the end users of products, processes or policies to ensure that the communities she works with are represented and have their needs met. she does this by employing evidence based practices to explore and organize how people in the community are impacted by product design, standards of practice (or lack thereof) and policy impact those people so that product design, process design and policy development is practical, implementable and actually support those who have to make things happen on the front line, on the shop floor or in their homes. her two areas of specialty are rehabilitation engineering with a focus on prosthetic and orthotic design in support the clinicians and patients and first responders with a focus on police and the police dog service. dr. raschke serves on a variety of professional and educational committees and is a board member and past vice president of the bcit faculty and staff association, in addition to being a member of the bcit emergency response team. she is the principle investigator for the centre for rehabilitation engineering and technology that enables (create). create is a collaborative venture between bcit and the neil squire foundation that was funded by the canadian foundation for innovation and the b.c. knowledge development fund (2001). https://doi.org/10.33137/cpoj.v1i1.30000 fiedler g, savage s, schull j, mankoff j. the case for broad-range outcome assessment across upper limb device classes. canadian prosthetics & orthotics journal. volume1, issue1, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.29970 professional opinion issn: 2561-987x all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x volume 1, issue 1 2 0 1 8 https://doi.org/10.33137/cpoj.v1i1.29970 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com fiedler g, savage s, schull j, mankoff j. the case for broad-range outcome assessment across upper limb device classes. canadian prosthetics & orthotics journal. volume1, issue1, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.29970 1 open access the case for broad-range outcome assessment across upper limb device classes volume 1, issue 1, article no. 4, august 2018 professional opinion the case for broad-range outcome assessment across upper limb device classes fiedler g1*, savage s2, schull j3, mankoff j 4 1 department of rehabilitation science and technology, school of health and rehabilitation sciences, university of pittsburgh, pittsburgh, pa, usa. 2 human computer interaction lab, computer science and electrical engineering department, west virginia university, morgantown, wv, usa. 3 e-nable, rochester enable limited, rochester ny. 4 allen school of computer science & engineering, university of washington, seattle, wa, usa. so, how valuable are those 3d-printed devices really for their users, and – be extension – for society at large? most reasonable people may feel that the truth, as for so many contested questions, is somewhere in the middle. the confidence boost from having a 3d printed superhero hand can be very real for a young patient, even if it is used only for short times. affordable customizations tailored to special tasks, such as holding a musical instrument,8 can make a big difference for young users, even if there is little utility beyond that. meanwhile, the e-nable community has progressed to be about more than mere device fabrication and distribution, with enablewebcentral having become a sophisticated platform for tracking cases, recruiting follow up feedback, and even providing referrals to and coaching from prosthetists. that devices produced by hobbyists would be able to outright replace much more expensive commercial prostheses is no longer being claimed by representatives of the e-nable community. instead, a mutually beneficial collaboration between the 3dprinting community and prosthetics and orthotics (p&o) professionals has been proposed.9 citation fiedler g, savage s, schull j, mankoff j. the case for broadrange outcome assessment across upper limb device classes. canadian prosthetics & orthotics journal. volume1, issue1, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i 1.29970 keywords prosthetics, 3d-printing, upper limb prosthetic, amputee, enable, low-cost prosthetic, prosthesis. *corresponding author dr goeran fiedler, phd, assistant professor, department of rehabilitation science and technology, university of pittsburgh, suite 403, bakery square, 6425 penn ave, pittsburgh, pa 15206, usa. orcid number: https://orcid.org/0000-0003-1532-1248 e-mail: gfiedler@pitt.edu tel: 412-624-6475 doi: https://doi.org/10.33137/cpoj.v1i1.29970 the emergence of 3d-printed upper limb prosthetic devices a couple of years ago, spearheaded substantially by the e-nable community,1, 2 has triggered a variety of reactions, ranging from euphoric press coverage predicting a new age of low-cost universally obtainable prosthetic solutions to anxious reluctance by clinicians fearing the demise of high-quality professional health care provision.3,4 the circumstance that untrained volunteers produce e-nable devices on their hobby-grade 3d-printers5 was both hailed as a revolutionary paradigm shift suited to address a host of current challenges in health care economics, and derided as inappropriate intrusion into long-standing training and certification standards of a well-regulated profession. that many of the early generation e-nable devices targeted young patients with partial hand amputation6 was interpreted by proponents as finally offering this neglected population long-desired solutions, whereas skeptics felt that many of the recipients of such devices would traditionally have been deemed to have a residual functional enough to be a contra-indication for a prosthesis.7 https://doi.org/10.33137/cpoj.v1i1.29970 https://doi.org/10.33137/cpoj.v1i1.29970 https://doi.org/10.33137/cpoj.v1i1.29970 https://orcid.org/0000-0003-1532-1248 mailto:gfiedler@pitt.edu https://doi.org/10.33137/cpoj.v1i1.29970 fiedler g, savage s, schull j, mankoff j. the case for broad-range outcome assessment across upper limb device classes. canadian prosthetics & orthotics journal. volume1, issue1, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.29970 2 open access the case for broad-range outcome assessment across upper limb device classes volume 1, issue 1, article no. 4, august 2018 news stories on the topic have recently become fewer and less sensationalist. on the other side, many prosthetics clinicians have come to realize that 3d-printing technology does have the potential to substantially change fabrication methods in the field, and that there is good reason to embrace the associated technological progress. it can be argued that the development already has brought some benefits for the field: • the publicity, even if partly unwarranted, may have triggered a greater interest in the p&o profession, attracting more talented students, and motivating new research opportunities. • some of the young patients who have been introduced to prosthetics through an, even unnecessary, e-nable device may be more likely to accept and use prostheses later on. • limb loss management being the first prominent area of using crowd intelligence to address healthcare challenges,10 an approach that promises wide applicability in the future,11,12 gives our field once more a pioneering role within the allied health sciences. still, while it may be easy to intuitively agree with many of those points, there is very little actual evidence on the underlying question of how effective 3d-printed upper extremity devices are in achieving their intended purposes. most of the research that has been published on the topic to date is limited to technical description and basic function testing of devices. there appears to be no pertinent outcome data of any kind for 3d-printed e-nable devices, let alone data that would allow comparison to conventional prosthetics. this gap can be addressed. the field of p&o has come a long way in establishing evidence based decision making. as new technology has been introduced in increasing frequency over recent decades, the necessity to demonstrate its benefits have yielded more and better research studies. outcome assessment, as a key component of evidence based practice, has rightfully become more and more important in the field over the past years. a great many different tools have been developed and are now available to allow for reliable data on most any conceivable assessment criterion. much important work has been and continues to be – done to determine validity of the various tools in different populations.13 while the availability of specialized outcome assessment tools is a benefit for the primary clinical purposes of documenting and monitoring individual patients’ rehabilitation progress, the respective data can – with limitations – also be useful to compare different interventions. certainly, this falls short of the scientific rigor of a prospective study with randomized group allocation, but, with a sufficiently large response rate, can deliver relevant descriptions of real-life outcomes to allow fact-based answers to our question and to inform future work. a group of researchers and clinicians led by jen mankoff (university of washington) and jon schull (e-nable) is pursuing this approach. having devised a comprehensive online questionnaire, efforts are currently focused on collecting a sufficient number of responses from both users of e-nable devices and conventional upper limb prostheses.14 this will allow a detailed, evidence-based, comparison between those device groups on a shared scale. as is common in prosthetics research in general, and in particular if targeting an upper limb loss population, it is a major challenge to obtain a large enough sample size to allow for generalizable conclusions. to address this issue, the survey has been translated into several foreign languages and is being advertised through a number of online and offline media. if it generates sound evidence on the effective differences between upper limb device classes, the respective discussion will become less biased and more constructive. given the recent developments in the field and the expanding device options for people with limb loss, it would be dangerous to assume that nothing new can be learned from such data. knowing what today’s patients want (or don’t want) and knowing what works (or doesn’t work) for them is important, not just for makers of 3d-printed devices but for trained prosthetists as well. clearly, databased innovation in prosthetic care is accelerating. with the participation of traditional clinicians, professional prosthetic services could both benefit and contribute. references 1. tanaka ks, lightdale-miric n. advances in 3d-printed pediatric prostheses for upper extremity differences. the journal of bone and joint surgery. 2016; 98: 1320-6. doi: 10.2106/jbjs.15.01212 https://doi.org/10.33137/cpoj.v1i1.29970 https://doi.org/10.2106/jbjs.15.01212 fiedler g, savage s, schull j, mankoff j. the case for broad-range outcome assessment across upper limb device classes. canadian prosthetics & orthotics journal. volume1, issue1, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.29970 3 open access the case for broad-range outcome assessment across upper limb device classes volume 1, issue 1, article no. 4, august 2018 2. zuniga j, katsavelis d, peck j, stollberg j, petrykowski m, carson a, fernandezet c. cyborg beast: a low-cost 3dprinted prosthetic hand for children with upper-limb differences. bmc research notes. 2015; 8: 10. https://doi.org/10.1186/s13104-015-0971-9 3. kesselring j, fiedler g. prosthetist’s assessment of additive manufacturing as an alternative to conventional manufacturing techniques in p&o. 42nd annual aaop meeting and scientific symposium. orlando, fl 2016. 4. hofmann m, burke j, pearlman j, fiedler g, hess a, schull j, hudson s, mankofet j. clinical and maker perspectives on the design of assistive technology with rapid prototyping technologies. proceedings of the 18th international acm sigaccess conference on computers and accessibility. acm, 2016, p. 251-6. doi: 10.1145/2982142.2982181 5. foster kr. 3-dimensional printing in medicine: hype, hope, and the challenge of personalized medicine. philosophy and engineering. springer, 2017, p. 211-228. doi.org/10.1007/978-3-319-45193-0_16. 6.burn mb, ta a, gogola gr. three-dimensional printing of prosthetic hands for children. the journal of hand surgery. 2016; 41: e103-e9. doi: 10.1016/j.jhsa.2016.02.008 7. james ma, bagley am, brasington k, lutz c, mcconnell s, molitor f. impact of prostheses on function and quality of life for children with unilateral congenital below-theelbow deficiency. the journal of bone and joint surgery. 2006; 88: 2356-65. doi: 10.2106/jbjs.e.01146 8. hofmann m, harris j, hudson se, mankoff j. helping hands: requirements for a prototyping methodology for upper-limb prosthetics users. proceedings of the 2016 chi conference on human factors in computing systems. acm, 2016, p. 1769-80. doi: 10.1145/2858036.2858340 9. schull j. toward collaboration: the 3d-printing community and o&p professionals the o&p edge. 2015, p. 88. [available at: https://opedge.com/articles/viewarticle/2015-04_12] accessed august 5. 2018. 10. schull j. enabling the future: crowdsourced 3d-printed prostheticsas a model for open source assistive technologyinnovation and mutual aid. proceedings of the 17th international acm sigaccess conference on computers & accessibility. acm, 2015, p. 1. 11. gleason c, ahmetovic d, savage s, toxtli c, posthuma c, asakawa c, et. al. crowdsourcing the installation and maintenance of indoor localization infrastructure to support blind navigation. proceedings of the acm on interactive, mobile, wearable and ubiquitous technologies. 2018; 2: 9. doi: 10.1145/3191741 12. savage s, monroy-hernandez a, höllerer t. botivist: calling volunteers to action using online bots. proceedings of the 19th acm conference on computer-supported cooperative work & social computing. acm, 2016, p. 813-22. doi>10.1145/2818048.2819985 13. lindner hy, nätterlund bs, hermansson lmn. upper limb prosthetic outcome measures: review and content comparison based on international classification of functioning, disability and health. prosthetics and orthotics international. 2010; 34: 109-28. doi/pdf/10.3109/03093641003776976. 14. mankoff j, savage s, eckert s, ngo c, fiedler g. user experiences with traditional and 3d-printed upper extremity prostheses, development of a comprehensive survey instrument. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32009 author biographies dr. goeran fiedler, is a credentialed prosthetist and orthotist, who holds additional graduate degrees in clinical engineering and health sciences. he has worked as a clinician and later researcher in the field of p&o for more than 25 years, and currently serves as assistant professor in the master of science prosthetics & orthotics program at the university of pittsburgh. his research interests are in assessing and improving prosthesis utilization, alignment, and prescription. dr. saiph savage is an assistant professor of computer science at west virginia university (wvu) where she directs the human computer interaction laboratory (hci @ wvu lab). she is also a visiting professor at the humancomputer interaction institute at carnegie mellon university (cmu), a j. wayne and kathy richards faculty scholar, and adjunct professor at the national autonomous university of mexico (unam). her research in social computing and crowdsourcing focuses on the design of systems that spark better coordination of volunteers and empower communities to reach more complex goals. https://doi.org/10.33137/cpoj.v1i1.29970 https://doi.org/10.33137/cpoj.v1i2.32009 fiedler g, savage s, schull j, mankoff j. the case for broad-range outcome assessment across upper limb device classes. canadian prosthetics & orthotics journal. volume1, issue1, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.29970 4 open access the case for broad-range outcome assessment across upper limb device classes volume 1, issue 1, article no. 4, august 2018 dr. jon schull, founder of enable: volunteers designing and delivering free 3d-printed prosthetics worldwide. a biological psychologist, inventor, entrepreneur, humancomputer interaction researcher, and digital community organizer, dr. jon schull is the creator of enable, an online philanthropic community that designs, customizes and fabricates open-sourced affordable 3dprinted prosthetic hands and arms for children and adults with upper limb differences. in past lives, schull was founder of softlock.com aka digitalgoods (nasdaq:digs) a seminal digital rights management company, professor and former director of the center for student innovation at rochester institute of technology. his current base of operations is the rochester enable lab at vertus high school. dr. jennifer mankoff is the richard e. ladner professor in the paul g. allen school at the university of washington. she earned her b.a. at oberlin college and her ph.d. in computer science at the georgia institute of technology. her research focuses on assistive technology for access, health and wellness, and takes a multifaceted approach that includes machine learning, 3d printing, and tool building. her research has been supported by google inc., the intel corporation, ibm, hewlett packard, microsoft corporation, and the national science foundation. she was awarded the sloan fellowship and the ibm faculty fellowship. https://doi.org/10.33137/cpoj.v1i1.29970 kelly k.m, joganic e, beals s.p, riggs j.a, mcguire m.k, littlefield t.r. a prospective study of cranial orthotic treatment of infants with isolated deformational brachycephaly. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32024 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) a prospective study of cranial orthotic treatment of infants with isolated deformational brachycephaly kevin m. kelly1, edward joganic2, stephen p. beals3, jeff a. riggs4, mary kay mcguire4, timothy r. littlefield*4 1 university of iowa, iowa city, ia, usa. 2 barrow cleft and craniofacial center, phoenix, az, usa. 3 southwest craniofacial center, phoenix, az, usa. 4 cranial technologies, tempe, az, usa. *email: tlittlefield@cranialtech.com doi: https://doi.org/10.33137/cpoj.v1i2.32024 objectives the study objectives were to prospectively evaluate treatment results of infants presenting with isolated deformational brachycephaly following use of a cranial orthosis, and to investigate the role of entrance age on efficacy of treatment. methods 128,014 infants presenting for consultation to one of thirty clinics were included from january 2013 through december 2017. nonsynostotic, nonsyndromic infants presenting with isolated deformational brachycephaly, characterized as a cephalic index > 90, and craniofacial asymmetry < 3 mm, were identified and filtered from the database. an analysis of variance (anova) was performed, examining the change in cephalic index with respect to three independent variables (entrance age, treatment time, initial cephalic index). results 4,205 infants were identified. mean entrance age was 5.8 months, and mean treatment time was 13.5 weeks. there was a statistically significant (p<0.001) improvement in cephalic index from 95.0 to 89.4 (an 81.4% improvement towards normal). the anova analysis demonstrated an inverse relationship between entrance age, and both treatment outcome and treatment time. cephalic index improved by 5.8%, 5.4%, and 4.3% in the >3 to < 6, > 6 to < 9, and >9 to 12 < month groups respectively. likewise, there was a statistically significant relationship between entrance age and treatment time (p<0.001). treatment time was 11.9, 15.8, and 17.4 weeks respectively. conclusion as discussed, deformation of the cranium in infancy represents a spectrum of deformity, ranging from severe asymmetric yet proportional distortion of the skull in plagiocephaly, to nearly symmetric yet disproportional distortion in brachycephaly. as such, the condition is best described as deformational plagiocephalybrachycephaly (dpb) with isolated plagiocephaly and/or isolated brachycephaly being at either ends of the spectrum. these findings demonstrate that the cranial orthosis is successful in the treatment of deformational brachycephaly, and that entrance age influences treatment results, with younger infants demonstrating both improved outcomes and shorter treatment times. key words deformational brachycephaly, cranial orthosis, flat head syndrome, cephalic index address correspondence timothy r. littlefield, cranial technologies, inc., 1395 w. auto drive, tempe az, 85248 [tlittlefield@cranialtech.com], phone: 480-4036332, fax: 480-505-1842 https://doi.org/10.33137/cpoj.v1i2.32024 mailto:tlittlefield@cranialtech.com https://doi.org/10.33137/cpoj.v1i2.32024 mailto:tlittlefield@cranialtech.com sykes a, stech n, laszczak p, mcgrath m, kercher a, zahedi s, moser d. performance of an activity monitor integrated into a microprocessor knee. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32031 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) performance of an activity monitor integrated into a microprocessor knee andy sykes*1, nadine stech1, piotr laszczak1, michael mcgrath1, alan kercher2, saeed zahedi1, david moser1 1endolite technology centre, basingstoke, uk. 2endolite north america, miamisburg, oh, usa. * email: andy.sykes@blatchford.co.uk doi: https://doi.org/10.33137/cpoj.v1i2.32031 introduction for many years, the biomechanical evaluation of prosthetic performance has centred around gait analysis and motion capture. while this provides useful, scientific insights, everyday life is not limited to straight-line, level, steady-state walking. with advancements in portable sensor technology in the last two decades, longterm activity monitoring (am) has become a more feasible and reliable prospect for accurately representing the real-world walking behaviour of patients. modern microprocessor knees (mpks) have begun to have this functionality built into the devices themselves, without the necessity for additional, external hardware. methods this study aimed to validate the am algorithm of one such mpk in a controlled laboratory environment. the participants were four transfemoral amputees (tfa) who regularly wore an mpk with in-built activity monitoring capabilities (orion3, endolite) day-to-day. a number of different activities were performed in order to test the robustness of the am algorithm: six minute walk tests (6mwt) on a treadmill at self-selected slow, medium and fast speeds; walking in a figure of 8; walking clockwise and anti-clockwise around a 3m square; walking up and down a ramp; walking up and down stairs. in order to provide validation for the algorithm, each participant wore a stepwatchtm am around the pylon, above the prosthetic ‘ankle’. all test sessions were video recorded and so a manual count from the video was taken as the ‘gold standard’ against which the two am outputs would be compared. results an ‘acceptable’ performance for each device was determined to be within 10% of the manual count4. both monitoring methods proved successful at achieving the target of <10% error, with near perfect agreement with the manual, video-based step count. for the square and ‘figure of 8’ tests, the stepwatch performed worse than it had during straight line walking, tending to overestimate the step count. the mpk algorithm performed very well during these tests, with <5% error. during stair walking, the stepwatch showed a good degree of accuracy, while the mpk was particularly susceptible to underestimation when gait compensation strategies were used (i.e. not walking step-over-step). figure 1: the activities performed for testing the step count algorithms conclusion the performance of the in-built step counting algorithm has been shown to be comparable to that of the market leading, purpose-built hardware device, for a range of activities. while improvements are still possible, the data recorded by this algorithm could help prosthetists make informed prescriptions to best suit the needs of the patient, as well as supporting justification for the reimbursement of advanced prosthetic technology. significance this technology could allow remote monitoring of patient activity, potentially providing data to justify reimbursement of advanced prostheses. https://doi.org/10.33137/cpoj.v1i2.32031 mailto:andy.sykes@blatchford.co.uk https://doi.org/10.33137/cpoj.v1i2.32031 sykes a, stech n, laszczak p, mcgrath m, kercher a, zahedi s, moser d. performance of an activity monitor integrated into a microprocessor knee. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32031 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) references 1.klute et al. prosthetic intervention effects on activity of lower-extremity amputees. arch phys med rehab 2006; 87(5):717-22. doi:10.1016/j.apmr.2006.02.007 2.orendurff et al. how humans walk: bout duration, steps per bout, and rest duration. j. rehabil. res. dev. 2008; 45(7):1077. doi: 10.1682/jrrd.2007.11.0197 3.arch et al. aaop annual meeting and scientific symposium. chicago, il, usa. 1-4 march 2017. 4.lee et al. validity of consumer-based physical activity monitors. medicine & science in sports & exercise. 2014 sep 1; 46(9):1840-8. doi:10.1249/mss.0000000000000287 disclosure the authors are employees of endolite north america or blatchford (the parent company of endolite north america); the manufacturer of the mpk evaluated in this study. https://doi.org/10.33137/cpoj.v1i2.32031 https://doi.org/10.1016/j.apmr.2006.02.007 https://doi.org/10.1249/mss.0000000000000287 gholizadeh h , ale ebrahim n, eshraghi a, lemaire e.d. research productivity trends in prosthetics and orthotics in canada. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32027 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) research productivity trends in prosthetics and orthotics in canada hossein gholizadeh 1* , nader ale ebrahim 2, arezoo eshraghi3, edward d lemaire 1 ,4 1ottawa hospital research institute, centre for rehabilitation research and development, ottawa, canada. 2 research support unit, centre of research services, university of malaya, malaysia. 3 holland bloorview kids rehabilitation hospital, toronto, canada. 4 university of ottawa, ottawa, canada. * email: gholizadeh87@yahoo.com introduction the canadian survey on disability reported about 3.8 million canadians between 15 and 64 years lived with a disability in 20121, and more than 80% used an assistive device. innovation, research, and unrestricted access to knowledge in prosthetics and orthotics is vital to improve a person’s quality of life, removing barriers, and integrating people with functional and mobility limitations into their society. therefore, this study examined trends in prosthetics and orthotics research in canada. methods scopus database was searched for prosthetics and orthotics articles with canadian origin in the last 30 years (1988-1997, 1998-2007, 2008-2017). publications from canada and the top ten countries were compared with the highest number of publication in this field, to find publication trends and forecast future trends (2018 to 2027). results the number of prosthetics and orthotics research publications showed a positive trend in the world and canada (figure 1). research productivity was more pronounced in orthotics versus prosthetics. table 1 compares the top ten countries with the most published articles. the united states ranked first followed by united kingdom. canada was third in orthotics and fourth in prosthetics, after germany. journals that published the most prosthetics and orthotics research were not open access. conclusion research publication trends in orthotics and prosthetics is promising in canada. while statistics show a positive global trend in the number of published articles, the number of journals that specifically publish prosthetics and orthotics research did not change, and few articles in these journals choose the optional open access publishing format. people with disabilities, including amputation, are a main consumer of research and innovations in this field. more publications in unrestricted access (open access) journals may enhance access to new knowledge and research in prosthetics and orthotics. figure 1: publication trends in prosthetics and orthotics in the world (top) and canada (bottom). doi: https://doi.org/10.33137/cpoj.v1i2.32027 https://doi.org/10.33137/cpoj.v1i2.32027 https://doi.org/10.33137/cpoj.v1i2.32027 gholizadeh h , ale ebrahim n, eshraghi a, lemaire e.d. research productivity trends in prosthetics and orthotics in canada. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32027 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) table 1: top ten countries with the most publications. percentages are change from the previous 10 years. prosthetic research 1988-1997 1998-2007 2008-2017 world 1424 2123 (49 %) 5110 (141%) us 465 589 (27%) 1644 (180%) uk 181 253 (40%) 510 (99%) germany 74 148 (100%) 344 (132%) canada 118 114 (-3%) 248 (118%) italy 25 82 (228%) 269 (228%) netherland 57 87 (53%) 226 (160%) china 8 73 (812%) 288 (259%) france 35 98 (180%) 167 (70%) australia 30 43 (43%) 186 (333%) sweden 27 51 (89%) 126 (147%) orthotic research 1988-1997 1998-2007 2008-2017 world 2760 5584 (102%) 10361 (86%) us 1287 2000 (55%) 3258 (63%) uk 273 656 (140%) 1005 (53%) canada 107 294 (175%) 558 (90%) japan 125 319 (155%) 469 (47%) australia 50 265 (430%) 503 (90%) china 14 81 (479%) 687 (748%) italy 41 143 (248%) 501 (250%) germany 69 202 (193%) 406 (101%) netherland 45 196 (336%) 287 (45%) iran 5 22 (340%) 412 (1773%) disclosure there is no conflict of interest in this study. references 1) disability in canada: initial findings from the canadian survey on disability. http://www.statcan.gc.ca/pub/89-654x/89-654-x2013002-eng.pdf (accessed 31october 2018). https://doi.org/10.33137/cpoj.v1i2.32027 http://www.statcan.gc.ca/pub/89-654-x/89-654-x2013002-eng.pdf http://www.statcan.gc.ca/pub/89-654-x/89-654-x2013002-eng.pdf jarrell j.d, garcia d.r, born c.t. inhibiting pseudomonas aeruginosa growth associated with prosthetic liners. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32016 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) inhibiting pseudomonas aeruginosa growth associated with prosthetic liners john d. jarrell*1,2,3,4,5, dioscaris r. garcia1,2,5 , christopher t. born,1,2,4,5 1alpert medical school at brown university, rhode island, usa. 2ri hospital, usa. 3materials science associates, usa. 4biointraface, usa. 5bi medical llc, usa. *email: johnjarrell@materialsscience.org doi: https://doi.org/10.33137/cpoj.v1i2.32016 introduction the conventional use of a prosthetic device by amputees involves contact of the residual limb tissue with the prosthetic socket using an intermediate elastomer liner. roll-on gel liners are applied directly to the limb, and slide into the rigid hard socket; the gels are generally silicone or plastic. regardless of the material, or the liner system used on a residual limb, problems occur because of direct skin and socket or liner contact1. the skin tissue of the residual limb is subject to compressive, shear, and tensile forces through weight bearing against the interface wall. in addition the skin is subject to heat/sweat issues that may be seasonal and related to the insulation properties of the interface material. a common problem encountered by the prosthetic user is socket odor, or odor emanating from socket liners2. proper hygiene does not guarantee the reduction of strong socket or liner odor over time. in addition, skin problems among amputees include rashes, blistering, mold/fungal infections and other skin irritations. the socket/wall interface (regardless of material composition) is subject to local skin sloughing, sweat, and skin oils in a warm/moist dark environment over hours of use providing an ideal environment for fungal and bacterial growth3. to address this problem, our team evaluated a titanium and silicone hybrid cleaning and coating technology containing a silver fatty acid complex against the odor producing, gram-negative, facultative anaerobe, pseudomonas aeruginosa4. methods the kirby bauer assay using pseudomonas aeruginosa was performed to test for the antimicrobial properties of standard prosthetic liner compared to liners cleaned and coated with a titanium silicone forming solutions dope with various levels of a silver-fatty acid complex (apocrine™, bi medical, coventry, ri). a lawn of bacteria was inoculated over tryptic soy agar. circular plugs were punched out of various liner materials and placed with the gel side in contact with the agar. coated and non-coated samples were used with 100% silver controls. the plate was incubated for 48 hours at 37oc and the assay was recorded every 24 hours via photography to measure the zone of bacterial growth inhibition. results no inhibition of bacteria was seen with uncoated liners against pseudomonas aeruginosa in a kirby bauer assay. the zone of inhibition increased with increasing levels of silver complex. interestingly, the uncoated hybrid liner material showed an increased halo of bacterial growth associated with the residual lubricant. this phenomenon was also observed in silicone liner materials, but was inhibited by the cleaning and coating process. conclusion during the testing of various liner materials cleaned and coated with a silver complex doped titanium and silicone hybrid in a kirby bauer bacterial-inhibition assay versus pseudomonas aeruginosa, it was evident that the control (uncoated) materials of hybrid and silicone composition were surrounded by a very dense concentration of bacteria. this phenomenon was evident after 24 hours of incubation at 37oc, but was very noticeable after 48hrs incubation even with the almost colorless properties displayed by p. aeruginosa in this assay. no other material tested displayed this phenomenon for the duration of the study. this observation suggests the possibility of a lubricating agent leaking out of the silicone and hybrid liner materials, which act as a chemoattractant for the bacteria. in essence, these results displayed the complete opposite effect from the treated mailto:*email:%20johnjarrell@materialsscience.org https://doi.org/10.33137/cpoj.v1i2.32016 jarrell j.d, garcia d.r, born c.t. inhibiting pseudomonas aeruginosa growth associated with prosthetic liners. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32016 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) materials, which showed a halo of bacterial inhibition surrounding their surface. significance the result of increased bacterial growth around the uncoated liner material is of particular importance due to the potential impact that the phenomenon could have with the stump-liner interface. if the liner is releasing a bacterial chemo-attractant, it could paradoxically potentiate an already favorable microenvironment to bacterial and fungal growth within the stump-liner interface. these findings may help explain prosthetic liner odor and stump irritation/infection even in the presence of good hygiene. effective cleaning and coating of prosthetic liners with liquid titanium-silicone-silver complexes is an available approach to reducing the odor associated with liner use. references 1. levy sw. skin problems of the leg amputee. prosthet orthot int. 1980;4:37-44. doi:10.3109/03093648009103113 2. koc e, tunca m, akar a, erbil ah, demiralp b, arca e. skin problems in amputees: a descriptive study. int. j. dermatol. 2008;47:463-6. doi: 10.1111/j.13654632.2008.03604.x 3. köhler p, lindh l, bjorklind a. bacteria on stumps of amputees and the effect of antiseptics. prosthet orthot int. 1989;13:149-51. doi:10.3109/03093648909079424 4. jarrell jd, dolly b, morgan jr. rapid screening, in vitro study of metal oxide and polymer hybrids as delivery coatings for improved soft-tissue integration of implants. j biomed mater res part a. 2010;92:1094-104. doi:10.1002/jbm.a.32435 disclosure authors have a financial interest and are consultants for bi medical. 1st and 3rd authors have a financial interest and consult for biointraface, inc. https://doi.org/10.3109/03093648009103113 https://doi.org/10.1111/j.1365-4632.2008.03604.x https://doi.org/10.1111/j.1365-4632.2008.03604.x https://doi.org/10.3109/03093648909079424 https://doi.org/10.1002/jbm.a.32435 mcdonald c.l, bennett c.l, rosner d.k, steele k.m. i am the boy with one hand who can do anything”: perceptions of ability among people with upper limb absence. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32001 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) i am the boy with one hand who can do anything”: perceptions of ability among people with upper limb absence cody l. mcdonald1*, cynthia l. bennett1, daniela k. rosner1, katherine m. steele1 1university of washington, usa. *email: codym@uw.edu doi: https://doi.org/10.33137/cpoj.v1i2.32001 introduction upper limb prostheses are commonly prescribed for people with upper limb absence (ula) to restore function, cosmesis, and assist with activities of daily living. however, nearly one in five people with ula chooses not to use a prosthesis1 and instead turns to alternative technology and adaptations, pointing to factors beyond prostheses that shape perceptions of ability and quality of life. we examined through interviews the lived experiences of people with ula framed around their perceptions of ability, device use, and quality of life. methods sample: convenience sample of individuals with ula. eligibility criteria:18 years of age or older with ula. study design: qualitative semi-structured interviews. procedures: semi-structured interviews were conducted with individuals with ula. participants also completed three surveys: orthotics and prosthetics users’ survey (opus)upper extremity, opus health quality of life index,2 and amputee body image scale.3 analysis: a team of five multidisciplinary researchers (a prosthetist, three designers, and a mechanical engineer) used an interpretive phenomenological analysis to identify common themes. two researchers coded each interview. open codes were then distilled into central themes through reduction. transcripts were then reviewed to identify final themes and representative text. results fourteen participants with ula, aged 18-71 years (mean age: 41.4±19 years, 7 males/7 females) participated in this research. most participants had congenital limb absence (10/14) of the distal limb (5 partial hand, 1 wrist disarticulation, and 5 transradial). six participants reported daily use of a prosthesis; all participants had prior experience with at least one type of conventional ulp (i.e., passive, body-powered, or myoelectric). five participants had also received e-nable 3d-printed devices, but no longer used them. survey: participants reported high functional ability during tasks of daily living (109.5 ± 2.6). individuals with congenital limb absence reported higher function (116.3 ± 18.7) compared to those with acquired ula (94.3 ± 23), which may reflect the influence of time since limb loss and learning. themes: participants shared high perceptions of ability and function, regardless of prosthesis or assistive technology use (table 1). life experiences related to three dimensions strongly influenced perceptions of ability: • learning to live with limb absence • integrating limb absence into individual identity • fostering supportive communities. the diversity of experiences across participants highlighted the limitations of identifying “normative” pathways of recovery or device use, emphasizing the need for flexible and adaptable systems to creatively support personal goals and needs. table 1: qualitative themes and representative quotes. mailto:codym@uw.edu https://doi.org/10.33137/cpoj.v1i2.32001 mcdonald c.l, bennett c.l, rosner d.k, steele k.m. i am the boy with one hand who can do anything”: perceptions of ability among people with upper limb absence. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32001 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) conclusion integration of novel platforms for professional practice, supportive communities, and technology innovation can support the evolving needs and care of people with ula. references 1. biddiss ea, chau tt. upper limb prosthesis use and abandonment: a survey of the last 25 years. prosthet. orthot. int.2007; 31, 236-257. doi: 10.1080/03093640600994581 2. heinemann, aw. bode rk, o'reilly c. development and measurement properties of the orthotics and prosthetics users' survey (opus): a comprehensive set of clinical outcome instruments. prosthet. orthot. int.; 27, 191-206 2003. doi: 10.1080/03093640308726682 3. gallagher p, et al. body image in people with lower-limb amputation: a rasch analysis of the amputee body image scale. am. j. phys. med. rehabil. 2007; 86, 205–215. doi: 10.1097/phm.0b013e3180321439 acknowlegements this work was supported by the national science foundation, grants no. cbet1452646,1453329, and 1423074. https://doi.org/10.1080/03093640600994581 https://doi.org/10.1080/03093640308726682 https://doi.org/10.1097/phm.0b013e3180321439 kruglov a, lein g, shvedovchenko i. modular principle to produce active prosthetic hand. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32026 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) modular principle to produce active prosthetic hand anton kruglov1,2*, gregory lein1, igor shvedovchenko2 1 scoliologic.ru, saint-petersburg, russia. 2 federal scientific center of rehabilitation of the disabled named after g.a. albrecht, saint-petersburg, russia. * email: kruglov@scoliologic.ru doi: https://doi.org/10.33137/cpoj.v1i2.32026 introduction we analyzed the functional prostheses including body powered prosthesis1 produced for partial hand amputation. there are almost no solutions on the world market for patients with partial hand amputation. there is no final solution for stump socket (inner socket) that could present both comfort for the stump and cosmetic look of the socket, and at the same time had partial possibility to take the load and transfer it to the power unit.2,3 methods the active hand prosthesis from our develop group was tested with a cohort of 45 patients 40 male and 5 female, aged 17-55 year old. we carried out questioning within 3 time intervals prior to supplying, immediately after initial instructing, and after 6 months of using the prosthesis. we used universal questionnaire for assessing the residual hand function dash. besides, we used a bench test, evaluating it by the score system before the prosthetics and after teaching how to use the prosthesis. all the patients with partial hand amputation were divided into groups 1.1 and 1.2. the 1.1 group was for patients with partial hand amputation at the level from second line of wrist bones to exarticulation in metacarpophalangeal joint. the 1.2 group patients with fingers amputation distal from heads of proximal phalanx (figure 1). figure 1. diagram of levels of amputations groups. before recommendation of active hand prosthesis for patients with above named defects the evaluation of wrist's function was made (the moving angle should be no less than 30 degrees), as well as of palm and fingers flexing muscles' force, as the grasp strength of artificial prosthesis fingers is directly proportional to this force. results the results obtained were statistically significant (p≤0,01) (figure 2, 3). the positive dynamics expressed by patients of group 1.1, revealed by 2nd questioning and preserved after 6 months of using the prosthesis indicates efficiency of using with active hand prosthesis of presented construction by patients from group 1.1. thus, indications for this prosthesis should be considered more than 50% loss of the hand functions due to amputation distal to the metacarpal joints, but proximal to the metacarpalphalangeal joints, including oblique amputation of the hand with loss of more than 3 fingers. the lack of positive dynamics in groups 1.2 and 2.2 is associated with high level of residual hand function in this category, which is reflected in the data of both the bench test and the questionnaire. figure 2. bench test results. mailto:kruglov@scoliologic.ru https://doi.org/10.33137/cpoj.v1i2.32026 kruglov a, lein g, shvedovchenko i. modular principle to produce active prosthetic hand. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32026 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) figure 3. dash results. so, contraindications for the active hand prosthesis of the presented design should be considered amputation at the fingers level, from the proximal phalanx and distally. conclusion the presented modular prefab system showed its versatility and stably positive result of prosthetics for patients with various partial hand amputations. acknowledgement this research and design work was carried out in the framework of the dissertation research in the federal scientific center of rehabilitation of the disabled named after g.a. albrecht under the guidance of prof. i.v. shvedovchenko, with the direct financial participation of "scoliologic.ru" l.l.c. and personally g.a. lein. references 1.kruglov a.v., shvedovchenko i.v. current state of functional prosthetic application in disabled persons with hand and finger stumps // genij ortopedii tom 23, no 3, 2017. doi: 10.18019/1028-4427-2017-23-3-368-373 2. schäfer m., dreher d., muders f., kunz s. prosthetic fitting after finger and hand amputations // special print from orthopädie technik 8/2014 – published by verlag orthopädietechnik, dortmund. 3. schulz s. first experiences with the vincent hand // "mec 11 raising the standard," proceedings of the 2011 myoelectric controls/powered prosthetics symposium fredericton, new brunswick, canada: august 14-19, 2011. copyright university of new brunswick. ghoseiri k, allami m, soroush m.r, rastkhadiv m.y. assistive technologies for pain management in amputees: a review. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32008 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) assistive technologies for pain management in amputees: a review kamiar ghoseiri1*, mostafa allami2, mohammad reza soroush2, mohammad yusuf rastkhadiv3 1 department of orthotics and prosthetics, school of rehabilitation sciences, hamadan university of medical sciences, hamadan, iran. 2 janbazan medical and engineering research center (jmerc), tehran, iran. 3 department of occupational therapy, school of rehabilitation sciences, hamadan university of medical sciences, hamadan, iran. *email: kamiar_g@yahoo.com doi: https://doi.org/10.33137/cpoj.v1i2.32008 introduction the prevalence of limb amputation is increasing globally as a devastating experience that can physically and psychologically affect the lifestyle of a person. the residual limb pain and phantom limb pain are common disabling sequelae after amputation surgery. assistive devices/technologies can be used to relieve pain in people with amputation. the present review aimed to introduce the existing assistive devices/technologies for pain management in people with amputation. methods an electronic literature search was performed in three databases of pubmed, isi web of science, and scopus to find articles that directly or indirectly reported pain management using assistive devices/technologies in people with amputation. all articles were evaluated by two independent reviewers to extract their demographic and methodological characteristics. moreover, the type of assistive device/technology and pain relief level were extracted for all articles. results the electronic search found 142 articles in the three chosen databases. after excluding duplicate and irrelevant articles, and those incompatible with review criteria, 9 articles were remained for evaluation and data extraction. conclusion the present review revealed there are few available assistive devices/technologies for pain management in people with amputation. the majority of the available assistive devices/technologies relieve pain conservatively. however, some of them are working by infusing a medication and some needs surgery to place some components inside body. there is a great need to portable, wireless, smart, and thin devices/technologies to stimulate the spinal cord and peripheral nerves by electrical, thermal, mechanical, or pharmaceutical stimulus. the overall pain relief cannot easily be compared among assistive devices/technologies in this review due to different study designs, interventions, and characteristics of participants. long-term randomized clinical trials are required to evaluate the effectiveness of available assistive devices/technologies. although some preliminary efforts have been done to resolve post amputation pain, more attention from researchers, clinicians, designers, engineers and manufacturers are required. figure 1. the procedure for selection of studies from three databases. mailto:kamiar_g@yahoo.com mailto:kamiar_g@yahoo.com https://doi.org/10.33137/cpoj.v1i2.32008 https://doi.org/10.33137/cpoj.v1i2.32008 ghoseiri k, allami m, soroush m.r, rastkhadiv m.y. assistive technologies for pain management in amputees: a review. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32008 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) significance • residual limb pain and phantom limb pain are common complaints of people with amputation. • there are few available assistive devices/technologies to relieve residual limb pain and phantom limb pain. • more attention to resolve post amputation pain is required from researchers, clinicians, designers, engineers and manufacturers references 1. dijkstra pu, et al. phantom pain and risk factors: a multivariate analysis. j pain symptom manage. 2002; 24, 57885. https://doi.org/10.1016/s0885-3924(02)00538-9 2. ephraim pl, et al. phantom pain, residual limb pain, and back pain in amputees: results of a national survey. arch phys med rehabil. 2005; 86, 1910-9. doi: 10.1016/j.apmr.2005.03.031 3. pet ma, et al. does targeted nerve implantation reduce neuroma pain in amputees? clin orthop relat res. 2014; 472, 2991-3001. doi: 10.1007/s11999-014-3602-1 disclosure the authors report no declarations of interest. however, the financial support of the research was done by the janbazan medical and engineering research center (jmerc). acknowledgments the authors would like to sincerely thank the financial support of the janbazan medical and engineering research center (jmerc), tehran, iran for this material. https://doi.org/10.1016/s0885-3924(02)00538-9 https://doi.org/10.1016/s0885-3924(02)00538-9 https://doi.org/10.1016/j.apmr.2005.03.031 https://doi.org/10.1016/j.apmr.2005.03.031 https://doi.org/10.1007/s11999-014-3602-1 https://doi.org/10.1007/s11999-014-3602-1 wismer n, krebs a, braatz f, schmalz t, kranzl a, breuer c. performance, patient benefits and acceptance of a new generation of microprocessor-controlled stance and swing control orthosis. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32020 1 open access abstract (poster presentation) aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 performance, patient benefits and acceptance of a new generation of microprocessor-controlled stance and swing control orthosis nadine wismer1, oa alexander krebs2, frank braatz3, thomas schmalz4, andreas kranzl2, christian breuer1 1 ottobock healthcare products gmbh, vienna, austria. 2 orthopädisches spital speising gmbh, vienna, austria. 3 pfh göttingen, germany. 4 ottobock healthcare gmbh, germany. email: nadine.wismer@ottobock.com doi: https://doi.org/10.33137/cpoj.v1i2.32020 introduction by enabling users to flex the orthotic leg during swing phase and safely lock it during stance phase, stance control orthosis (sco) offers clear benefits compared to locked knee-ankle-foot-orthosis (kafo)1. since such orthoses do not offer dampened knee flexion in the weight-bearing condition, this represents a limitation in everyday activities such as ramp and stair descent. c-brace, a microprocessor controlled stance and swing orthosis (ssco), overcomes many of those problems. maximum knee flexion angle in stance and swing phase during level walking are closer to physiological values with c-brace compared to conventional kafos2. the patients are with c-brace able to descend stairs and ramps reciprocally2. furthermore, patients report of safer and easier ability to perform activities of daily living3. the main aim of next generation c-brace is a reduction in size and an increase of adaptability to the patient’s anatomic structure. due to technological changes, improvements especially for difficult adls (e.g. walking on uneven ground) are expected. methods in this prospective, multicenter pilot study incorporating 3d gait analysis patients suffering from either lower limb paresis or flaccid paralysis (unilateral or bilateral) will be enrolled. patients’ previous orthosis, if available, will not be a criterion for inclusion / exclusion. after baseline measurement with previous orthosis or no orthosis, patients proceed to phase i – the system set up. in the phase i the orthotic shells will be designed and fitted to the patients and they will be introduced to the use of the new ssco. in the phase ii the new ssco will be used during daily life for 6 months. during that time measurements will be conducted every two month. collected data include the following: (1) biomechanical 3d gait analysis to assess performance during walking and stair descent, (2) performance based measures assessing safety and walking performance, (3) selfreported outcome measures to assess activities of daily living, pain and quality of life. results the study is currently running and seven patients have been enrolled. three patients have flaccid paralysis due to polio and four patients have traumatic lower limb paresis (one bilateral and two unilateral). patients’ mean age is 59.1 ± 10.6 years and the mean time since the diagnosis is 31.3 ± 22.5 years. furthermore, mean height is 166.0± 10.1 cm and mean weight is 68.1 ± 13.8 kg. preliminary data suggests very high user satisfaction with the new ssco. patients report of increased safety and reduction in difficulty of performing activities of daily living. in particular, the improvements could be observed in advanced activities of daily living such as walking in crowd, walking on uneven ground, stepping on small objects and stair descent. the study should be finalized and data collected by june 2018. conclusion in this study, extensive feedback from new ssco users will be gathered after six months of home use. due to the technological changes regarding the sensor system, it is essential to analyse and evaluate its impact on patient’s gait pattern and activities of daily living to be able to optimize and refine the control method. testing the new ssco under everyday life conditions is of special interest based on the fact that the potential user population shows large variation regarding activity level and residual motor function and therefore demand for stability / support and the behaviour during performance varies too. mailto:nadine.wismer@ottobock.com https://doi.org/10.33137/cpoj.v1i2.32020 wismer n, krebs a, braatz f, schmalz t, kranzl a, breuer c. performance, patient benefits and acceptance of a new generation of microprocessor-controlled stance and swing control orthosis. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32020 2 open access abstract (poster presentation) aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 significance clinical outcome measures will provide quantitative data. additionally, feedback from clinicians, orthopaedic technicians and physiotherapists will help to direct product development in a customer oriented fashion. references 1.zacharias b & kannenberg a. clinical benefits of stance control orthosis systems: an analysis of the scientific literature. j prosthet orthot. 2012; 24(1), 2-7. doi: 10.1097/jpo.0b013e3182435db3 2. schmalz t et al. a functional comparison of conventional knee-ankle-foot orthoses and a microprocessor-controlled leg orthosis system based on biomechanical parameters. prosthet orthot int. 2016; 40(2), 277-286. doi:10.1177/0309364614546524 3. pröbsting e et al. safety and walking ability of kafo users with the c-brace orthotronic mobility system, a new microprocessor stance and swing control orthosis. prosthet orthot int. 2017; 41(1), 65-77. doi:10.1177/0309364616637954 disclosure nadine wismer and christian breuer are full time employees of the ottobock health care products gmbh. https://doi.org/10.1177/0309364614546524 https://doi.org/10.1177/0309364616637954 henness d, medema a, steinhorst k, moauro r, reuland m, whelan r, kester s, bateni h. changes in postural steadiness following trans-tibial amputations. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32014 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) changes in postural steadiness following trans-tibial amputations douglas henness, arianna medema, kendra steinhorst, robert moauro, michael reuland, robert whelan, shawna kester, hamid bateni* physical therapy program, northern illinois university, dekalb, il, usa. *email: hbateni@niu.edu doi: https://doi.org/10.33137/cpoj.v1i2.32014 introduction increased risk of falling following amputation is well documented in literature1. as the amputee population ages, accidental falls become a greater problem. trans tibial amputations are one of the most common levels of amputation. we hypothesized that postural steadiness is deteriorated following trans-tibial amputation as compared to age matched younger adults. methods data from three trans-tibial amputees (51±16 years old) and six healthy age matched (48±19 year old) were analyzed. participants were instructed to stand (bare feet heels together, 5-7 degrees toe-out) on a force platform and were tested for three standing conditions: aeyes open, beyes closed and cstanding on airex 2.5” thick balance pad (www.airex.com). each test was repeated three times (block randomized). force platform data were collected for 35 seconds. anteroposterior and mediolateral time series data were filtered through a fourth-order zero phase butterworth low-pass filter with cut-off frequency of 5 hz. the first 8 sec. and last 2 sec. of data were cut off to remove any potential lead-in/out effect. results analysis of variance on time and frequency domain variables of sway indicated significant differences among amputees vs. non-amputees. mean mediolateral sway distance and the standing conditions were significantly different (f(1,5)=5.83, p<0.05 and f(1,5)=3.84,, p<0.05 respectively). the maximum ml sway velocity was also affected by amputation (f(1,5)=17.66,, p<0.0001). in frequency domain variables, power in ml direction was both affected by amputation (f(1,5)=10.66, p<0.001) and test condition (f(1,5)=4.16, p=0.019). 95% ap power frequency and centroidal frequency were also affected by amputation (p=0.013 and 0.003 respectively). figure 1. comparison of ml postural sway of amputees (yamp) and non-amputees (namp) for three standing conditions of 1 (eyes open), 2(eyes closed) and 3 (standing on foam). horizontal cross line indicated median and diamond shape indicates mean value of the data. conclusion our results indicate that postural steadiness is altered following amputation both in time and frequency domain. significance assessment of postural steadiness in both time and frequency domain can reveal a new aspect in assessment of balance and postural control among amputees and can lead to more effective training exercises as well as optimizing prosthetic component designs to reduce accidental fall among this population. references 1c. gauthier-gagnon, m. c. grise, and d. potvin, enabling factors related to prosthetic use by people with transtibial and transfemoral amputation. arch. phys. med. rehabil. 1999; vol. 80, pp. 706–713. disclosure no conflict of interest exists for this study. mailto:hbateni@niu.edu https://doi.org/10.33137/cpoj.v1i2.32014 o'byrne m, mcfadyen a k, hannett d, mcgarry a. measurement of the consistency of patella-tendon-bearing modification using cad. canadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 research article issn: 2561-987x all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x volume 1, issue 1 2 0 1 8 https://doi.org/10.33137/cpoj.v1i1.30006 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com anadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 o'byrne m, mcfadyen a k, hannett d, mcgarry a. measurement of the consistency of patella-tendon-bearing modification using cad. canadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 1 open access patella-tendon-bearing modification using cad volume 1, issue 1, article no. 2, july 2018 research article measurement of the consistency of patella-tendon-bearing modification using cad o'byrne m1, mcfadyen ak2, hannett d3, mcgarry a1* 1 department of biomedical engineering, university of strathclyde, uk. 2 akm statistics, glasgow, uk. 3 ability matters, abingdon, oxford, uk introduction computer aided design (cad) is now commonly used in prosthetic clinical practice1 and current scanners have been shown to have a high level of accuracy during the shape capture process.2 saunders et al implied that shape capture using cad can save considerable time and make the process more quantifiable. they also acknowledged that models may be stored electronically and easily replicated, unlike plaster where modified plaster models are usually destroyed during socket fabrication which makes socket duplication more difficult.3 the most common level of amputation is transtibial therefore this is the focus of this study.4 abstract study design: pilot study background: computer aided design (cad) is now commonly used in prosthetic clinical practice. to create a patellar tendon bearing (ptb) socket, further modification of the transtibial shape is required. objectives: to investigate the consistency of transtibial shape modification for a ptb socket design using cad. methods: 13 transtibial models with marked anatomical landmarks were made, each linked to a fictitious patient history. three clinicians were asked to complete modification for a ptb socket with suspension sleeve at weekly intervals over the course of three weeks. measurements were recorded at landmarks and compared for intra and inter reliability. results: clinicians showed high intraclass and interclass correlation (icc) values with narrow confidence intervals for the tibial tubercle, medial and lateral flares and distal end of the tibia. one clinician demonstrated moderate intra rater reliability for modification over the patellar tendon. all other icc values for the patellar tendon and fibular head modification were low. inter rater reliability was not calculated for fibular head and patellar tendon as intra icc values should be above 0.6. conclusions: all clinicians showed good consistency at tibial tubercle, distal tibia, medial and lateral flares. patellar tendon (0.345< icc < 0.641) and fibular head (0.165< icc < 0.513) showed poorer consistency and require improvement. article info received: march 29, 2018 accepted: july 1, 2018 published: july 14, 2018 citation o'byrne m, mcfadyen a k, hannett d, mcgarry a. measurement of the consistency of patellatendon-bearing modification using cad. canadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj. v1i1.30006 keywords prosthetics, transtibial, computer aided design, cad, shape capture, modification. *corresponding author dr anthony mcgarry, phd in prosthetics and orthotics, senior teaching fellow, department of biomedical engineering, university of strathclyde, wolfson centre, 106 rottenrow, glasgow, uk, e-mail: anthony.mcgarry@strath.ac.uk doi: https://doi.org/10.33137/cpoj.v1i1.30006 https://doi.org/10.33137/cpoj.v1i1.30006 https://doi.org/10.33137/cpoj.v1i1.30006 mailto:anthony.mcgarry@strath.ac.uk https://doi.org/10.33137/cpoj.v1i1.30006 anadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 o'byrne m, mcfadyen a k, hannett d, mcgarry a. measurement of the consistency of patella-tendon-bearing modification using cad. canadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 2 open access patella-tendon-bearing modification using cad volume 1, issue 1, article no. 2, july 2018 two fundamentally different designs of transtibial prosthetic socket are currently used clinically: the patellar tendon bearing (ptb) and the total surface bearing socket (tsb). the ptb socket is one in which pressure tolerant areas (mainly the patellar tendon) are loaded and pressure sensitive areas (bony prominences) are relieved.5 alteration to the shape captured is carried out by the clinician, who removes material from pressure tolerant areas and adds material to pressure sensitive areas, either by using plaster or on cad. the tsb socket, first described by murdoch6, used water casting to load all of the surface area of the residual limb including pressure sensitive areas. the tsb design is based on the hydrostatic principle for load transfer.7 with a tsb socket minimal modification is required meaning that the final socket is likely to be more consistent as less clinical judgement is involved.8 the tsb socket was described as long ago as 1968, however, ptb sockets are still commonly prescribed in clinical practice. ptb sockets have shown to have higher variation in interface pressures in comparison to tsb sockets and a recent systematic review has demonstrated higher satisfaction with tsb sockets.9 ptb sockets however have a lower cost associated, and due to budget constraints this may be an important factor.10 it is also important to consider that tsb sockets may not be suitable for all users as they are generally prescribed with a liner which provides the suspension. it could be argued that both socket styles have an application and the clinician should use appropriate prescription criteria based on individuals’ requirements. modification, however, may lead to less consistency as more personal judgement and human error is involved. a previous study by convery et al11 looked into the consistency of ptb cast rectification with plaster. it was found that a clinician varied by up to 4.3mm. although the clinical significance of a variation this size has not been tested one may assume that 4mm removed over a bony prominence might cause discomfort. shape capture for ptb sockets is carried out whilst the patient is sitting and without loading of the residual limb soft tissue. modification is therefore required to allow forces to be transferred to the residual limb when the patient is statically and dynamically loading the prosthesis. other shape capture methods have been developed to simulate soft tissue loading that occurs during stance; such as pressure casting and water casting. such loading facilitates total surface bearing and therefore minimises the modification process. research in prosthetic shape capture is relatively limited. the majority of studies on the topic were prior to 1990 and considering that cad has made a huge technological advancement in the recent years this was unanticipated. only a few studies10,12 exist relating to the consistency of ptb modification one of which was conducted in 2003 using a small sample and using plaster.10 this study aims to evaluate the consistency of ptb modification using cad, which has not been investigated previously. method thirteen transtibial models were prepared by the researcher from a generic computer model on a leading prosthetic cad system (willowwood tm tracer v12.2). a brief fictitious clinical note was compiled to accompany each model, which indicated the soft tissue consistency, time since amputation, gender, areas of sensitivity, adherent scars, and a brief social history. three clinicians were recruited from a single prosthetic centre using a poster inviting them to participate. protocols for the investigation were approved by university of strathclyde ethical committee. the poster was placed in the prosthetics office for a week and interested clinicians asked to contact the chief investigator, after which time they received a participant information sheet and consent form. three clinicians with appropriate availability within the confines of the project timescale responded. clinicians were asked to randomly select an identifier from a hat that numbered clinicians a-c. no one knew the identity of the clinician apart from the clinicians themselves. clinicians were asked to write their allocated letter within an envelope and write their name on the outside in case they forgot their identifier. anadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 o'byrne m, mcfadyen a k, hannett d, mcgarry a. measurement of the consistency of patella-tendon-bearing modification using cad. canadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 3 open access patella-tendon-bearing modification using cad volume 1, issue 1, article no. 2, july 2018 clinicians were provided with a computer with willowwood tm tracer software v12.2 installed. three clinicians (a, b and c), with minimum three months’ experience using cad, were given 13 on screen transtibial models to modify. to achieve a power calculation of 80%, 13 models were used. all clinicians were familiar with the tracer software and the scanner used for shape capture. a total of six clinically important landmarks were identified on each computer model by the researcher: patellar tendon, tibial tubercle, fibular head, distal end of tibia, medial flare and lateral flare. to ensure safe transfer of data, clinicians were provided with instructions at the start of each week on how to download relevant files from a secure storage platform strathcloud and how to upload the modified models when complete. they were asked to read the accompanying clinical note and modify as they normally would for a ptb socket without supracondylar suspension. the order of the models was randomised using a random number generator per clinician, per week. modification of models was based on clinician interpretation using the clinical note and on screen presentation. modified models were then saved securely on the computer and uploaded to strathcloud for researcher access. clinicians operated in isolation and were not given access to the other participants’ work. this process was repeated for all 13 models. this was then repeated after a one-week interval and then again after two weeks. circumference, medio-lateral (ml) and anteroposterior (ap) measurements were recorded for all landmarks, for all models. only those measurements deemed clinically relevant were statistically analysed (table 1). this decision was made following discussion between the chief investigator, the researcher and a leading cad expert. however, all raw measurement data exists for all landmarks to facilitate future evaluation. when outlining the medial and lateral flares more than one marker was used in order to show the bony landmark. the middle point of both the medial and lateral flare was used in analysis to simplify the results. the peak difference was recorded for patellar tendon and fibular head. this was carried out by overlaying the modified model over the original in tracer, the software calculated the distance between the two landmarks. the results were then statistically analysed using ibm spss v21 to estimate the intraclass correlation coefficient (icc) model (2,1)., the confidence interval (ci) and statistical significance. for those landmarks with an icc of above 0.6 the interclass was calculated.13 to evaluate the homogeneity of the data, the standard deviation was calculated for each landmark. for results and statistical analysis, clinicians a, b and c were renumbered 1-3 using a random number generator so the clinicians were unable to identify their own results. table 1: selection of measurements at landmarks. results to simplify study results, only those measurements deemed clinically relevant will be discussed. the icc value indicates the level of reliability of modification between the weeks (intra) and between the clinicians (inter). a value of 1 is perfect reliability whereas 0 indicates no reliability. as seen in table 2 the intra icc values for the tibial tubercle, medial flare, lateral flare and distal tibia were high. this suggests that the clinicians are able to perform these modifications relatively consistently between weeks, with little variation. the confidence intervals for all were narrow indicating 95% probability that true reliability was indeed close to these values. as shown in table 2 the interclass icc values for tibial tubercle, medial flare, lateral flare and distal tibia are high (icc>0.7), suggesting that the process of modification is also consistent across the clinicians. the medial and lateral flare modifications are the most reliable as they have very high icc values with narrow confidence intervals. the standard deviations for all landmarks were also calculated (table 3). the values for medial and lateral flares were the largest indicating heterogeneous data. anteroposterior circumference peak patella tendon x tibial tubercle x fibula head x lateral flare x medial flare x distal tibia x anadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 o'byrne m, mcfadyen a k, hannett d, mcgarry a. measurement of the consistency of patella-tendon-bearing modification using cad. canadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 4 open access patella-tendon-bearing modification using cad volume 1, issue 1, article no. 2, july 2018 table 2: icc, ci and significance values for each landmark. poor icc<0.6, moderate icc 0.6-0.7, good icc>0.7 (11) table 3: standard deviation (sd) for each landmark. the standard deviation values for tibial tubercle, medial flare, lateral flare, and distal tibia were also relatively large. table 2 shows that the icc values for the patellar tendon were low (icc<0.7), which suggest poor intra rater reliability of modification at this landmark. although one clinician achieved a moderate icc value at the patellar tendon, this value would ideally require further improvement to demonstrate good reliability in a clinical setting. all icc values at fibular head were low although one clinician performed better in comparison to the other clinicians (table 2). the confidence intervals at the fibular head and patellar tendon are wide indicating less certainty in results. the standard deviations, as highlighted by table 3, for the patellar tendon and fibular head were low (sd 0.58-1.5). this may indicate relatively homogenous data for these landmarks; which could mean that a small variation may have had a disproportionate effect on the icc value. discussion the variation in the results between the clinicians suggests that experience, skill and interpretation may have an impact on the consistency of modification. as shown in table 2, one clinician (clinician 2) demonstrated moderate intra rater reliability (icc=0.641) of modification of the patellar tendon, two other clinicians showed poor reliability (icc<0.6). it was therefore not possible to determine inter rater reliability (between clinicians) as clinicians failed to demonstrate sufficient intra rater reliability. variation between clinicians was also evident at the fibular head but to a lesser degree. clinician 2 was able to achieve a higher icc value (icc=0.513) compared to the other clinicians, however, results still demonstrated poor reliability. reliability may be poor since the patellar tendon and fibular head required more targeted plaster removal/addition and this may have led to more clinician 1 clinician 2 clinician 3 wk1 wk2 wk3 wk1 wk2 wk3 wk1 wk2 wk3 patella tendon 1.17 0.93 0.88 1.50 0.87 1.04 1.03 1.05 1.13 tibial tubercle 7.59 7.54 7.83 7.80 7.46 7.34 7.05 7.46 7.50 fibula head 1.23 1.50 0.95 0.80 0.58 0.90 1.41 0.91 0.75 medial flare 24.50 25.20 25.01 24.90 24.06 23.91 23.65 24.84 24.23 lateral flare 26.65 27.44 26.88 26.89 25.74 25.76 26.42 28.07 27.61 distal tibia 8.96 9.26 8.96 8.93 8.27 7.94 8.58 9.41 8.85 patella tendon peak measure icc [95% ci] p tibial tubercle ap measure icc [95% ci] p fibula head peak measure icc [95% ci] p medial flare circumference measure icc [95% ci] p lateral flare circumference measure icc [95% ci] p distal tibia ap measure icc [95% ci] p intra clinician reliability clinician 1 0.400 [0.062,0.737] p=0.011 0.974 [0.933,0.992] p<0.001 0.166 [-0.137,0.571] p=0.160 0.995 [0.988,0.999] p<0.001 0.996 [0.989,0.999] p<0.001 0.990 [0.970,0.997] p<0.001 clinician 2 0.641 [0.339,0.858] p<0.001 0.994 [0.984,0.998] p<0.001 0.513 [0.171,0.795] p=0.002 0.995 [0.987,0.998] p<0.001 0.995 [0.988,0.999] p<0.001 0.985 [0.947,0.995] p<0.001 clinician 3 0.345 [0.041,0.681] p=0.01 0.950 [0.722,0.987] p<0.001 0.165 [-0.155,0.566] p=0.170 0.991 [0.967,0.997] p<0.001 0.994 [0.979,0.998] p<0.001 0.960 [0.902,0.986] p<0.001 inter clinician reliability 0.989 [0.898,0.997] p<0.001 0.998 [0.976,0.999] p<0.001 0.996 [0.986,0.999] p<0.001 0.976 [0.925,0.993] p<0.001 anadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 o'byrne m, mcfadyen a k, hannett d, mcgarry a. measurement of the consistency of patella-tendon-bearing modification using cad. canadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 5 open access patella-tendon-bearing modification using cad volume 1, issue 1, article no. 2, july 2018 variation in modification at these points. measurements examined for patellar tendon and fibular head were peak measures whereas other landmarks used ap or circumference measures, this may have had an effect on the results. whilst the icc values suggest that the modification at the patellar tendon was not reliable, actual maximum variation was 3mm. it is debatable as to whether or not such a difference in modification would be clinically significant as very little scientific evidence appears to exist which suggests optimal modification in relation to socket fit. future research is required to determine the clinical impact of modification variation on the resulting socket fit. low standard deviation values for the patellar tendon and fibular head (table 3) may indicate that clinicians did not vary modification between the patients, and therefore were not fine tuning the modification depending on patient shape and their needs. the relatively large standard deviation values for tibial tubercle, medial flare, lateral flare and distal tibia suggest that clinicians varied modification most based on the patient residuum shape and clinical notes at these landmarks. a minimum of 3 months’ experience was required in order to participate in this study. in hindsight, it may have been more appropriate for the frequency with which clinicians use software to be in the inclusion criteria. for example, a clinician could have been trained in using cad for years but only use it once a month compared to a clinician who was trained two months ago but uses it five times a day. in future, it would be interesting to evaluate the effect of clinician experience and training on reliability of modification, particularly in the areas that showed less reliability (patellar tendon and fibular head). data on experience was not gathered in this experiment as it would have identified the clinicians to the researcher and therefore had associated ethical issues. the tibial tubercle, medial flare, lateral flare and distal tibia expressed high icc values and were highly statistically significant, showing that in general the modification procedure in these areas was consistent. all six landmarks were considered clinically important, as they are key weight bearing and weight relieving areas. modification of the patellar tendon and fibular head was inconsistent, however, improvements in these areas could be achieved and it may be possible to improve reliability of the overall process. therefore, in order to improve consistency, it is important to focus on these two landmarks. clinician 2 achieved a moderate icc at the patellar tendon, unlike the other clinicians, which suggested that there might be techniques that can be used to increase reliability. using the ‘blend’ tool after carrying out modifications may have caused inconsistency as it works by smoothing the build up to the surrounding area. therefore, this makes the modification less precise and more variation is likely. if there was a limit on the blend tool so it could not alter the modification by more than 1mm this may cause less variation. if there was a method in which a standardised procedure for modification was developed this could lead to more consistent results. research in southampton attempted to achieve this by creating a library of shapes to apply as a standard modification. however this was abandoned due to the large amount of variables involved.2 when gaining measures at each landmark on tracer, the mouse cursor was placed over the point of the landmark. however, as the system works to 0 decimal place there was a 1mm radius in which the cursor could be placed and the system stated it was directly on the landmark. within this 1mm radius the circumference/peak/ap/ml measurement sometimes varied by up to 2mm. there were also some associated errors when gaining the peak measurements. the modified model had to be overlaid on the original model, and aligned by eye. one clinician extended the model proximally by 50mm each time and in order to align models this extension had to be removed. due to the system rounding to 0 decimal places this may have introduced further error. in future research, errors could be reduced by requesting that clinicians do not reduce the ply and also requesting that one landmark be left unmodified in order to assist with alignment. as clinicians did not mark on the landmarks themselves they may have interpreted them to represent different sites of bony anatomy. for example, one clinician may have interpreted the marker to be the border of the bone, whilst another may have interpreted the marker it to be the area that should have been modified. if the clinicians watched the marker placement on a residual limb prior to be scanned and were given an opportunity to palpate the anatomy themselves this may potentially have an anadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 o'byrne m, mcfadyen a k, hannett d, mcgarry a. measurement of the consistency of patella-tendon-bearing modification using cad. canadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 6 open access patella-tendon-bearing modification using cad volume 1, issue 1, article no. 2, july 2018 effect on reliability. similarly, clinicians may have interpreted clinical notes differently. soft tissue was described but this is not quantitative. if clinicians were given an opportunity to assess patients this may also have an effect on reliability. it could be argued that a shape capture technique where no modification is required could eliminate the problem of modification consistency. although pressure casting appears to be less reliant on the clinicians’ skill there may still be an aspect of variation due to clinical judgement. ossur’s icecast technical manual14 recommends inflating the bladder between 40mmhg-120mmhg dependent on activity level and shape of the residual limb. therefore, it would be interesting to carry out the same experiment but using the icecast method of shape capture to evaluate the variation due to changes in pressure. as each residuum is different there is always going to be an aspect of tailoring to an individual and therefore a certain amount of variation. it may be more clinically relevant to carry out this research on real patient residual limbs linked to feedback on the socket comfort when fitted.15 a socket comfort score could be used along with pressure analysis of the inside of the socket. although consistency leads to a more scientific process it is important to appreciate that consistency does not necessarily lead to comfort. limitations as the clinicians were aware that models were not real patients it may have affected performance. clinicians carried out the 13 modifications in one session, which may have led to participant fatigue. in a few cases it appeared that the clinicians might have omitted to carry out the modification at a landmark, which would have affected results. a clinician in error did not carry out modification of one model, for one week. this was therefore not included in the results. as this was for one out of the 13 models it will not have had much of an impact on the final results but it is important to note that the sample size will be smaller for this clinician. although three clinicians and 13 models give a power calculation of 80% this may not be a large enough subject group to generalise the results clinically. this study took place in a single prosthetic centre using the software of one cad system, where the clinicians have a very high cad usage in comparison to plaster and therefore may not be representative of all clinicians. future research should aim to use clinicians from multiple centres and analyse the inter reliability between different sites. conclusion this study illustrated the reliability of modification by three clinicians at six important clinical landmarks. four clinically relevant landmarks exhibited good consistency (tibial tubercle, distal tibia, medial and lateral flares), and two landmarks required further improvement (patellar tendon and fibular head) which required more targeted modification, which may have led to inconsistency. further research should be conducted in multiple centres to assess the clinical relevance of these results by determining the effect of varying modification on socket fit. author contribution all authors contributed equally in the preparation of this manuscript. acknowledgements we would like to thank the three clinicians who participated in this study, and ms sally bell for her assistance with the literature research. declaration of conflicting interests the authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. ethical approval protocols for the investigation were approved by university of strathclyde ethical committee. references 1. mcgarry t, mchugh b, buis a, mckay g. evaluation of the effect of shape on a contemporary cad system. prosthetics and orthotics international. 2008;32(2):145-54. doi: 10.1080/03093640802015920. doi:%2010.1080/03093640802015920. anadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 o'byrne m, mcfadyen a k, hannett d, mcgarry a. measurement of the consistency of patella-tendon-bearing modification using cad. canadian prosthetics & orthotics journal, volume 1, issue 1, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30006 7 open access patella-tendon-bearing modification using cad volume 1, issue 1, article no. 2, july 2018 2. 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1968;5(3):15-21. 7. kristinsson o. the iceross concept: a discussion of a philosophy. prosthetics and orthotics international. 1993;17(1):49-55. doi:10.3109/03093649309164354. 8. dumbleton t. trans-tibial prosthetic system design and benefits for the amputee, service providers and society: an evidence based clinical study. university of strathclyde; 2007. 9. safari mr, meier mr. systematic review of effects of current transtibial prosthetic socket designs—part 1: qualitative outcomes. journal of rehabilitation research and development.2015;52(5):491-508. doi: 10.1682/jrrd.2014.08.0183. 10. selles rw, janssens pj, jongenengel cd, bussmann jb. a randomized controlled trial comparing functional outcome and cost efficiency of a total surfacebearing socket versus a conventional patellar tendon-bearing socket in transtibial amputees. archives of physical medicine and rehabilitation. 2005;86(1):154-61. https://doi.org/10.1016/j.apmr.2004.03.036. 11. convery p, buis awp, wilkie r, sockalingam s, blair a, mchugh b. measurement of the consistency of patellartendon-bearing cast rectification. prosthetics and orthotics international.2003;27(3):207-213. doi:10.1080/03093640308726683. 12. mohammad reza safari, philip rowe, angus mcfadyen, and arjan buis. hands-off and hands-on casting consistency of amputee below knee sockets using magnetic resonance imaging. the scientific world journal. 2013, article id 486146, doi: 10.1155/2013/486146. 13. evers a. the revised dutch rating system for test quality. international journal of testing. 2001; 1(2):155-82. 14. plaster of paris casting with iceross compact. reykjavik: ossur; 2010. [available from: http://assets.ossur.com/lisalib/getfile.aspx?itemid=7926.]. 15. hanspal rs, fisher k, nieveen r. prosthetic socket fit comfort score. disability and rehabilitation. 2003;25:12781280. doi:10.1080/09638280310001603983. doi:%2010.1682/jrrd.%202014.10.0272. doi:%2010.1682/jrrd.%202014.10.0272. doi:%2010.3109/%2003093648509164819 doi:10.3109/03093649309164354. doi:%2010.1682/jrrd.2014.08.0183. https://doi.org/10.1016/j.apmr.2004.03.036. doi:10.1080/03093640308726683. doi:%2010.1155/2013/486146. doi:%2010.1155/2013/486146. http://assets.ossur.com/lisalib/getfile.aspx?itemid=7926 doi:10.1080/09638280310001603983 senczyszyn a, duncan j.c. health care accessibility for individuals with disabilities: barriers and risk factors impacting care. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32046 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) health care accessibility for individuals with disabilities: barriers and risk factors impacting care abbey senczyszyn*, j. chad duncan northwestern university prosthetics-orthotics center, usa. *email: abbey.senczyszyn@northwestern.edu doi: https://doi.org/10.33137/cpoj.v1i2.32046 background healthcare professionals have certain professional, legal, and ethical obligations that they must fulfill with each patient interaction. though professional and legal obligations may vary between fields of practice, the core ethical responsibility remains the same: provide just health care1. this requires that healthcare professionals are aware of systemic and institutional factors that lead to disparity and discrimination in the provision of health services1. disability is a complex construct that can be related to various factors related to health condition as well as social and environmental factors that influence participation. this complexity results in varying definitions; the icf model of disability was used in this research2. figure 1. icf framework2 methods inclusion criteria: • health care in the united states • individuals with a physical disability or limitation • discussion of disparity and accessibility related to the provision of healthcare • publication date of january 1, 2014 or later • data from 2010 or later • age 18 and older exclusion criteria: • studies irrelevant to health care in the united states • individuals with a mental disability or hard of hearing • specialty care irrelevant to the purposes of this study • pediatric patient population • full text not available. https://doi.org/10.33137/cpoj.v1i2.32046 senczyszyn a, duncan j.c. health care accessibility for individuals with disabilities: barriers and risk factors impacting care. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32046 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) preliminary results: access barriers figure 2. commonly cited barriers preventing access to healthcare evaluated in current literature3,5-8,10-12,15,20-21 preliminary results: risk factors figure 3. commonly cited risk factors potentially resulting in healthcare disparity evaluated in current literature3-5, 8-11,13-14,1622. limitation • non-homogenous populations • varying data sources. discussion disparity in the provision of health care is not a new topic of discussion; however, past research has primarily focused on age, racial/ethnic, and socioeconomic disparities related to health care. recently, arguments have been made that people with disability also experience disparity in the receipt of health care services. this research sought to compile the most commonly cited factors that are thought to factor into this inequality. despite the implementation of various legislative measures including the americans with disability act and, more recently, the patient protection and affordable care act, disparity still exists in the provision of health care. the most commonly cited barriers include transportation5,7,9-11,14,19-20, care coordination4-5,9-11,14, and physical access to a health care provider7,10-11,14,19-20. certain groups are more likely to experience these barriers to care, the most commonly cited significant factors being age9-10,13,15-16,19,21, race/ethnicity9,12-13,15-21, and gender10,15,18-19. references 1. american society for bioethics and humanities. (2011). core competencies for healthcare ethics consultation (2nd ed.). glenview, il: author. 2. world health organization. international classification of functioning, disability, and health. geneva, switzerland: world health organization; 2001. 3. gulley sp, rasch ek, chan l. difference, disparity, and disability: a comparison of health, insurance coverage, and health service use on the basis of race/ethnicity among us adults with disabilities, 2006-2008. medical care. 2014;52(10 suppl 3):s9-16. doi:10.1097/mlr.0000000000000129 4. bogner et al. patient satisfaction and perceived quality of care among older adults according to activity limitation stages. archives of physical medicine and rehabilitation. 2015;96(10):1810-9. doi:10.1016/j.apmr.2015.06.005 5. hall jp, kurth nk, chapman sl, shireman ti. medicaid managed care: issues for beneficiaries with disabilities. disability and health journal. 2015;8(1):130-5. doi: 10.1016/j.dhjo.2014.08.010 6. kennedy j, wood eg, frieden l. disparities in insurance coverage, health services use, and access following implementation of the affordable care act: a comparison of disabled and nondisabled working-age adults. inquiry : a journal of medical care organization, provision and financing. 2017. doi:10.1177/0046958017734031 7. krahn gl, walker dk, correa-de-araujo r. persons with disabilities as an unrecognized health disparity population. american journal of public health. 2015;105 suppl 2:s198206. doi: 10.2105/ajph.2014.302182 8. lin s-f, beck an, finch bk. black–white disparity in disability among u.s. older adults: age, period, and cohort trends. the journals of gerontology: series b: psychological sciences and social sciences. 2014;69(5):784-97. https://doi.org/10.1093/geronb/gbu010 https://doi.org/10.1097/mlr.0000000000000129 https://doi.org/10.1016/j.apmr.2015.06.005 https://doi.org/10.1016/j.dhjo.2014.08.010 https://doi.org/10.1177/0046958017734031 https://doi.org/10.1093/geronb/gbu010 senczyszyn a, duncan j.c. health care accessibility for individuals with disabilities: barriers and risk factors impacting care. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32046 3 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) 9. mcclintock hf, kurichi je, kwong pl, xie d, streim je, pezzin le, et al. disability stages and trouble getting needed health care among medicare beneficiaries. american journal of physical medicine & rehabilitation. 2017;96(6):408-16. doi:10.1097/phm.0000000000000638 10. pezzin le, bogner hr, kurichi je, kwong pl, streim je, xie d, et al. preventable hospitalizations, barriers to care, and disability. medicine. 2018;97(19):e0691. doi: 10.1097/md.0000000000010691 11. bauer se, schumacher jr, hall a, marlow nm, friedel c, scheer d, et al. disability and physical and communicationrelated barriers to health care related services among florida residents: a brief report. disability and health journal. 2016;9(3):552-6. doi:10.1016/j.dhjo.2016.03.001 12.brenner ab, clarke pj. understanding socioenvironmental contributors to racial and ethnic disparities in disability among older americans. research on aging. 2018;40(2):103-30. doi:10.1177/0164027516681165 13.brucker dl, rollins ng. trips to medical care among persons with disabilities: evidence from the 2009 national household travel survey. disability and health journal. 2016;9(3):539-43. doi:10.1016/j.dhjo.2016.01.001 14. de vries mcclintock hf, barg fk, katz sp, stineman mg, krueger a, colletti pm, et al. health care experiences and perceptions among people with and without disabilities. disability and health journal. 2016;9(1):74-82. doi:10.1016/j.dhjo.2015.08.007 15. dobbertin k, horner-johnson w, lee jc, andresen em. subgroup differences in having a usual source of health care among working-age adults with and without disabilities. disability and health journal. 2015;8(2):296-302. doi: 10.1016/j.dhjo.2014.08.012 16. gimm g, blodgett e, zanwar p. examining access to care for younger vs. older dual-eligible adults living in the community. disability and health journal. 2016;9(3):431-8. doi:10.1016/j.dhjo.2015.12.004 17. horner-johnson w, dobbertin k. usual source of care and unmet health care needs: interaction of disability with race and ethnicity. medical care. 2014;52(10 suppl 3):s40-50. doi:10.1097/mlr.0000000000000193 18. mahmoudi e, meade ma. disparities in access to health care among adults with physical disabilities: analysis of a representative national sample for a ten-year period. disability and health journal. 2015;8(2):182-90. doi: 10.1016/j.dhjo.2014.08.007 19. ryan j, abrams mk, doty mm, shah t, schneider ec. how high-need patients experience health care in the united states. findings from the 2016 commonwealth fund survey of high-need patients. issue brief (commonwealth fund). 2016;43:1-20. 20. stillman md, frost kl, smalley c, bertocci g, williams s. health care utilization and barriers experienced by individuals with spinal cord injury. archives of physical medicine and rehabilitation. 2014;95(6):1114-26. doi:10.1016/j.apmr.2014.02.005 21. torres h, poorman e, tadepalli u, et al. coverage and access for americans with chronic disease under the affordable care act. ann intern med. 2017; 166(7):472-479. doi:10.7326/m16-1256 acknowledgements & disclosure i would like to thank dr. j. chad duncan for his help during this project: providing guidance and feedback during the development of this research. this research was developed as part of the nupoc curriculum. no funding sources or sponsorships were provided during the completion of this research. https://doi.org/10.1097/phm.0000000000000638 https://doi.org/10.1097/md.0000000000010691 https://doi.org/10.1016/j.dhjo.2016.03.001 https://doi.org/10.1177/0164027516681165 https://doi.org/10.1016/j.dhjo.2016.01.001 https://doi.org/10.1016/j.dhjo.2015.08.007 https://doi.org/10.1016/j.dhjo.2014.08.012 https://doi.org/10.1016/j.dhjo.2015.12.004 https://doi.org/10.1097/mlr.0000000000000193 https://doi.org/10.1016/j.dhjo.2014.08.007 https://doi.org/10.1016/j.apmr.2014.02.005 https://doi.org/10.7326/m16-1256 mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.3. https://doi.org/10.33137/cpoj.v2i1.32723 issn: 2561-987x volume 2, issue 1 2019 (online) case study all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com m mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.3. https://doi.org/10.33137/cpoj.v2i1.32723 1 open access perforated prosthetic liners volume 2, issue 1, article no.3, august 2019 https://jps.library.utoronto.ca/index.php/cpoj/index case study the influence of perforated prosthetic liners on residual limb wound healing: a case report mcgrath m.1*, mccarthy j.1, gallego a.1, kercher a.2, zahedi s.1, moser d.1 1 blatchford group, unit d antura, bond close, basingstoke, rg24 8pz, uk. 2 endolite north america, miamisburg, oh, usa. introduction the interface between the residual limb and the prosthetic socket is, arguably, the most crucial part of successful prosthetic prescription.1 without a comfortably fitting socket, the patient will not wear their prosthesis. the skin and soft tissue of the residual limb are particularly susceptible to damage. contrary to historic biomechanical assumptions, there is evidence to suggest that this interface should be considered as an extra joint in the lower limb, with translation and rotation,2,3 which lead to unnatural loading profiles. there may also be scar tissue and, if the amputation aetiology was dysvascular, the tissue is at greater risk of pressure ulcers,4 which cannot heal as well5 and could result in revision surgery or reamputation.6 another issue that exacerbates the problem is excessive sweating.1,7–10 when questioned about the factors affecting abstract case description: good residual limb skin health is vital to successful prosthetic prescription. unnatural loading profiles and excessive sweating can lead to skin and soft tissue problems. perforated liners allow the transport of moisture away from the skin and allow negative pressure (a condition that has been shown to aid wound healing) to act directly on the residuum surface. aim: assess the effects of perforated prosthetic liner use, particularly with respect to wound healing. method: three patient histories were retrospectively reviewed following prescription of perforated prosthetic liners due to excessive sweating or prolonged residual limb health concerns. photographic records from patient files were used to document changes in residual limb condition. patients also provided subjective feedback regarding their experiences. findings: two cases described active amputees with persistent blistering irritated during exercise. another case described a patient of low mobility level with a history of residual limb skin infections. all saw their conditions heal and reported a reduction in problematic sweating. two patients reported cancelling surgical interventions after substantial improvements with the perforated liner. discussion: these findings provide evidence that the use of perforated prosthetic liners allow improvements in residual limb health, while still permitting prosthetic use. citation mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.3. https://doi.org/10.33137/cpoj.v 2i1.32723 keywords perforated liner, residual limb, wound healing, sweating, vacuum, lower limb prosthetics. *corresponding author dr. michael mcgrath, research scientist – clinical evidence blatchford group, unit d antura, bond close, basingstoke, rg24 8pz, united kingdom email: mike.mcgrath@blatchford.co.uk website: blatchford.co.uk doi: https://doi.org/10.33137/cpoj.v2i1.32723 article info received: may 23, 2019 accepted: july 29, 2019 published: august 1, 2019 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v2i1.32723 https://doi.org/10.33137/cpoj.v2i1.32723 mailto:mike.mcgrath@blatchford.co.uk https://doi.org/10.33137/cpoj.v2i1.32723 m mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.3. https://doi.org/10.33137/cpoj.v2i1.32723 2 open access perforated prosthetic liners volume 2, issue 1, article no.3, august 2019 https://jps.library.utoronto.ca/index.php/cpoj/index their quality of life and their satisfaction with their prostheses, up 70% of lower limb amputees have reported that they consider sweating a problem7,11 and up to twothirds claim that sweating adversely affects their activities of daily living (adl).12 the causes of excessive sweating in amputees are clear. it has been reported that trans-tibial amputees use 10-40% more energy than able-bodied people to walk and perform daily tasks.13,14 they also have a reduced surface area (approximately 10-15% less), which affects the capacity to transfer heat energy and cool down.15 consequently, the body’s natural response is to produce more perspiration. furthermore, the use of prosthetic liners, made of silicone, polyurethane or tpe gel, creates an even warmer environment locally, around the residual limb because they often have poor thermal conductivity.16,17 this impermeable18 micro-climate is moist, warm and nutrientrich, making it ideal for bacterial growth. the sweat is stasis on the residuum surface instead of evaporating, which can lead to skin problems, such as dermatitis.19–21 there is evidence that liner material selection can reduce residuum temperatures,22 such as the alpha smarttemp liner (willowwood, roseburg, or, usa), which uses phase change material that stores and releases heat energy. however, it is unknown whether this is sufficient to reduce thermal discomfort.23 regardless, even if sweating is reduced, what perspiration does occur will remain on the skin, so associated problems remain. in light of this, “breathable” prosthetic liners have been developed, which have permeable surfaces to allow the transfer of air and moisture away from the skin, such as silcare breathe (blatchford, basingstoke, uk) with laser-drilled perforations and softskin air (uniprox, zeulenrodatriebes, germany) with micro-pores. this report describes cases of patients with residual limb health conditions who were fitted with perforated liners. methodology participants the case histories in this study were collected retrospectively. once relevant cases were identified, the patients were approached and they were asked to provide written consent for their case to be described. the inclusion criteria included being over the age of 18, being able to provide informed consent, having a trans-tibial amputation, being a prosthetic limb wearer, having a history of residual limb health issues and having changed to a perforated prosthetic liner. perforated liners there were two types of perforated prosthetic liner used in these cases; one (silcare breathe cushion,a blatchford, uk) used with elevated vacuum suspension (evs) or a passive vacuum and the other (silcare breathe locking,b blatchford, uk) used with a pin-lock. the ‘cushion’ version has a rounded distal cap and is used in conjunction with a suspension sleeve. a distal one-way valve in the socket allows the use of suction suspension or evs. laser-drilled perforations are distributed along the length of the liner. there are also perforations in the distal cap. on the pinlock version, the perforations stop a short distance from the distal end. at the distal cap, a valve opens when the wearer bears load and closes again when the limb is lifted from the ground, creating a small area of passive vacuum in the area distal to the perforations in the wall of the liner, which facilitates the retention of the residuum within the liner. data collected demographic data were collected from the patients in each case. these included gender, age, k level and any relevant comorbidities. their prosthetists were asked to describe the patients’ prosthetic prescription, including suspension and ankle/foot technologies, before and after they were fitted with the perforated liner, to identify any potentially compounding factors for consideration. photographic evidence of residual limb health conditions was gathered to verify the clinicians’ own patient notes. since the analysis was performed retrospectively, photos were only available when the clinician, or the amputee themselves, had seen fit to take one. these images were used for a qualitative examination of changes in residual limb health. findings three case histories were collected, covering different demographics, prosthetic preferences and residual limb health issues. since the analysis was retrospective and gathered from different centres, the detail included in the patient records was variable between cases (table 1). case #1 the patient was a 41-year-old male with a right-sided, trans-tibial amputation caused by a road traffic collision approximately four years prior. he was 90kg in mass, with a body mass index (bmi) of 28.4 and he had been classified as a k3-k4 level walker. following limb loss, the patient wished to return to his previously active lifestyle, including regular jogging, walking and cycling. however, exercise, combined with his silicone liner had led to excessive perspiration building up, remaining on the surface of his residuum and collecting distally. the patient reported that this caused relative movement between the residuum and the liner and chaffing. blisters would develop in and around the scars at the distal end of his residuum, where sweat collected (figure 1a). jogging on consecutive days led to prosthetic disuse on the third day because the blisters made limb wearing too painful. https://jps.library.utoronto.ca/index.php/cpoj/index https://www.blatchford.co.uk/ m mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.3. https://doi.org/10.33137/cpoj.v2i1.32723 3 open access perforated prosthetic liners volume 2, issue 1, article no.3, august 2019 https://jps.library.utoronto.ca/index.php/cpoj/index in fact, the patient had booked a surgery to revise the scarring at the distal end of his residuum, in the hope that it would help to reduce blister formation. as a result of sweating issues, the patient was fitted with a locking, perforated liner on 19th june 2017. it was believed that he would prefer the pin-lock version because it removed the necessity to wear a suspension sleeve. at initial fitting, the patient reported finding the liner comfortable to wear and easy to don. a follow-up appointment was carried out after a month on 24th july 2017. the patient reported that the liner remained comfortable, with good prosthetic control. he had continued jogging and walking and although he felt that his limb felt about the same temperature, there had been considerably less sweat on his limb after doffing the liner, which he described as only a “slight glisten” on the skin. his prosthetist reported no skin breakdown and improvements in the existing blistering had led the patient to postpone his surgery. there was a review appointment after three months in september 2017, at which time the patient was regularly going for 8km jogs, the blistering had healed (figure 1b) and he had cancelled the surgery. figure 1: the condition of the case #1 patient’s residual limb (a) before being fitted with a perforated liner and (b) after three months of use. case #2 the patient was a 45-year-old male with a right-sided, traumatic, trans-tibial amputation. he was 100kg in mass, with a bmi of 30.2 and he had been classified as a k3-k4 level walker. prior to and since his amputation, the patient enjoyed competing in motocross endurance races. for these competitions, he would wear a carbon blade-style prosthesis with a sole plate and pin-lock silicone liner. however, he struggled with excessive sweating on his residual limb and had skin issues since 2014. an ulcer developed on the posterior-distal aspect of his residuum (figure 2a) and it worsened to the extent that his doctor had mentioned the possibility of further amputation to a transfemoral level. the ulcer had persisted for over a year before he was initially fitted with a locking, perforated liner on 27th august 2018 (figure 2b). in that time the patient used “no medicine, no cream, no lotion” and was advised to use “only soap and water” to clean the wound. when asked what the dermatology clinic advised him, the patient explained “they said the white heavy skin that look like a callous around the wound (figure 2b), was from moisture. they told me i would have to take my leg off for 3 to 5 months for it to completely heal”, which was impractical for him as he was in full-time employment. the residual limb condition was monitored at regular intervals over the first three months of perforated liner use at 4, 7, 9, 11 and 13 weeks. when compared to the initial fitting stage (figure 2b), at 4 weeks (24th september 2018 figure 2c), the ulcer had visibly reduced in size and the wound was no longer suppurating. at 7 weeks (15th october 2018 figure 2d), tissue was granulating and the affected area/ulcer had reduced in size. it was at this point that the patient changed to a cushion, perforated liner and northene socket, copolymer polypropylene frame, passive vacuum adaptive expulsion valve system. over the following 6 weeks, the ulcer reduced in size considerably (1st and 12th november 2018 figure 2e and f), before being considered fully healed 13 weeks after initial fitting (28th november 2018 figure 2g). since healing, the patient has been fitted with a hydraulic ankle unit for use with his passive vacuum system. he has also continued to compete in motocross endurance events (for which he uses the locking perforated liner), achieving ‘top 5’ finishes against able-bodied competitors. a b case age (years) mass (kg) bmi k level amputation type/side residual limb issue previous prescription new prescription #1 41 90 28.4 k3k4 trans-tibial /right distal blisters around scarring cushion silicone liner with suction suspension pin-lock perforated liner #2 45 100 30.2 k3k4 trans-tibial /right posterior ulcer/wound pin-lock silicone liner with bladext foot 1st: pin-lock perforated liner 2nd: cushion perforated liner with suction suspension #3 50 106 31.0 k2low k3 trans-tibial /right distal maceration and infection cushion silicone liner with suction suspension and tres foot cushion perforated liner with evs and k2-specific hydraulic ankle table 1: summary table of the cases described https://jps.library.utoronto.ca/index.php/cpoj/index m mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.3. https://doi.org/10.33137/cpoj.v2i1.32723 4 open access perforated prosthetic liners volume 2, issue 1, article no.3, august 2019 https://jps.library.utoronto.ca/index.php/cpoj/index figure 2: the condition of the case #2 patient’s residual limb (a) approximately one year before being fitted with a perforated liner, (b) at the point of fitting, and after (c) 4 weeks of use, (d) 7 weeks of use (the point of changing to passive vacuum suspension), (e) 9 weeks of use, (f) 11 weeks of use and (g) 13 weeks of use. case #3 the patient was a 50-year-old male (mass: 106kg, bmi: 31.0), with a right-sided, trans-tibial amputation, classified as a k2 to low k3 level walker. he habitually wore an energy-storing-and-return (esar) foot. the patient had chronic residual limb skin issues for approximately eight years. excessive perspiration had led to the skin becoming macerated and infected (figure 3a and b). the patient had reported “being on the brink of revision surgery” to remove the affected skin. he was fitted with a perforated cushion liner, in conjunction with a passive vacuum, in 2016. in 2017 this was upgraded to an evs system that used the movement of a hydraulic ankle unit to draw greater vacuum levels. after three months of using this prosthetic prescription, the patient reported that he thought it was “doing a great job” of keeping his skin dry; he was wound free and had had no residuum problems. the patient has continued to use this prescription for over a year, during which time his residuum remains in good health (figure 3c). figure 3: the condition of the case #3 patient’s residual limb (a) in its worst condition in 2011, (b) in 2013 and (c) in march 2019, after continued use of a perforated liner (since 2016) with elevated vacuum suspension and hydraulic ankle (since august 2017). discussion this research illustrates the health benefits of maintaining a dry residuum/socket interface by the use of perforated liners. while the use of silicone liners is primarily for comfort and impact absorption, providing a close fit and suspension,10 they can create warm, moist environments in which bacteria can thrive. creating a dry environment mitigates against the risks of skin maceration and infection. such conditions lead to uncomfortable socket fits and prosthetic abandonment. also, intuitively, the presence of a b c d e f g a b c https://jps.library.utoronto.ca/index.php/cpoj/index m mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.3. https://doi.org/10.33137/cpoj.v2i1.32723 5 open access perforated prosthetic liners volume 2, issue 1, article no.3, august 2019 https://jps.library.utoronto.ca/index.php/cpoj/index sweat will lubricate this interface, increasing relative motion between the residuum and the liner. this may affect prosthetic control and/or suspension, potentially reducing swing clearance and become a tripping hazard. subsequent compensatory movements to improve clearance increase energy expenditure24 and may have a degenerative effect on musculoskeletal health.25–27 in their review of prosthesis thermal discomfort in 2014, ghoseiri and safari10 described available options for management of excessive heat and perspiration in the prosthetic socket. they refer to antiperspirants, local ointments and topical sprays to inhibit the physiological process of sweating but cite unpleasant odors and potential allergies as drawbacks.10 an alternative is the use of botulinum toxin (botox) injections but this is described as invasive, requiring repeated treatment to maintain effectiveness and may potentially cause pain and/or side effects.10 they ultimately concluded that prosthesis thermal discomfort was still an unresolved problem. notably, this review was published prior to the commercialisation of perforated prosthetic liners. the wounds arising from sweating can also have a substantial impact on the economics of healthcare. treatment and care of patients with skin health conditions, such as pressure ulcers and chronic wounds, cost the uk national health service (nhs) up to £3.1 billion per annum.28,29 although this number is for the population as a whole, amputees will be disproportionately affected, particularly those with vascular comorbidities. these issues can lead to socket adjustments or replacements, which studies have shown constitute a sizeable proportion of clinical appointments,30,31 creating a time and financial burden for limb centres. additionally, two cases in this analysis reported considering surgical interventions as a result of their skin conditions, which were cancelled after tissue improvements following the use of perforated liners. other reported treatments to reduce excessive sweating, such as botox injections32 or daily antiperspirant use,32 can be expensive, inconvenient, produce side effects or have limited effectiveness. if a change in prosthetic liner prescription can provide the desired effect, it may be the most cost-effective approach. as far as the authors are aware, this is the first published evidence for the effects of “breathable” liners. some practitioners may be concerned that the perforations in liners may create areas of stress concentration that may increase the rate of deterioration of the liner itself or damage the surrounding skin. many liner manufacturers offer warranty periods of between six and 12 months, or three months for suspension sleeves. perforated liners have a six month warranty so although there may be a greater risk of degradation than a non-perforated liner, the longevity is still within typical industry standards for this type of prosthetic component. although none of these three cases reported any skin issues around the perforations, the manufacturer’s instructions for usec warn that “enlarged perforations can trap the skin and cause blisters” and recommend that should the perforations become damaged, the patient should cease the use of the liner. it should be noted that there might have been other influences present in these cases. although cases #1 and #3 didn’t report the use of other wound healing treatments, such as creams or ointments, it is possible that the patients might have used these therapies without reporting such to a member of their treatment team. han and ceilley’s33 review of chronic wounds describes many topical therapies and dressings that could assist wound healing but the practicality of these treatments within a prosthetic socket environment is unclear. one of the patients also began using evs with their perforated liner. evs has previously been shown to reduce residuum volume fluctuation34–38 and relative movement,34,37,39,40 which reduces interface pressure.41 this, combined with encouraging healthier, more hydrated, more oxygenated tissue,42 might explain why residual limb wounds have been observed to heal faster with evs,43 without discontinuing prosthetic use.44– 46 negative pressure wound therapy (npwt) is a widely used technique to aid wound healing47,48 and has been demonstrated to be effective even for diabetic amputees.49 the perforations in the liner allowed the vacuum to be applied directly to the wound surface, potentially further helping healing. two of the cases began using hydraulic ankles with their perforated liners. these devices significantly reduce interface pressures, loading rates and deep tissue trauma,50 which may also have contributed to improvements in residual limb condition. the current study was also limited in that the analysis was performed retrospectively, each clinical team had their own methods of monitoring the patients’ skin conditions and there were other prescription changes that may have influenced wound healing (e.g. prosthetic suspension method). future work will consist of a more regimented, scientifically rigorous analysis with a wider cohort of patients. patients will be divided into two groups; the control group will use regular silicone liners and the intervention group will use perforated liners. patients will be monitored at pre-defined, regular intervals. the progress of wound healing will be quantified, using metrics such as wound surface area, as described in hoskins’ work.46 compounding factors, such as prosthetic componentry and suspension method will be controlled to isolate the effects of liner perforations only. acknowledgements the authors would like to thank the prosthetists and patients involved in providing the information for the cases in this study. https://jps.library.utoronto.ca/index.php/cpoj/index m mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.3. https://doi.org/10.33137/cpoj.v2i1.32723 6 open access perforated prosthetic liners volume 2, issue 1, article no.3, august 2019 https://jps.library.utoronto.ca/index.php/cpoj/index declaration of conflicting interests the authors are full time employees of the manufacturer of the prosthetic liners evaluated in this study. sources of support blatchford clinical services who documented and provided patient care. author contribution • michael mcgrath, conceptualization, case collation, writing original, review and editing. • joseph mccarthy, conceptualization, case collection, analysis, writing original, review and editing. • ana gallego, analysis, writing original, review and editing. • alan kercher, conceptualization, case collection, analysis, review and editing. • saeed zahedi analysis, writing original, review and editing. • david moser analysis, writing original, review and editing. manufacturers’ documentation a https://www.blatchford.co.uk/endolite/silcare-breathe-cushionliner/ b https://www.blatchford.co.uk/endolite/silcare-breathe-lockingliner/ c https://www.blatchford.co.uk/catalogue/liners/silcare-breathelocking/ifu/938398_iss1%20-%20locking%20liner.pdf. references 1.legro mw, reiber g, del aguila m, ajax mj, boone da, larsen ja, et al. issues of importance reported by persons with lower limb amputations and prostheses. j rehabil res dev. 1999 ;36(3):155-163. 2.tang j, mcgrath m, laszczak p, jiang l, bader dl, moser d, zahedi s. characterisation of dynamic couplings at lower limb 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long-term prosthesis use. j rehabil res dev. 2008; 45: 15. doi: 10.1682/jrrd.2006.11.0147 26.lloyd ch, stanhope sj, davis is, royer td. strength asymmetry and osteoarthritis risk factors in unilateral trans-tibial, amputee gait. gait posture. 2010;32(3):296300. https://doi.org/10.1016/j.gaitpost.2010.05.003 27.lemaire ed, fisher fr. osteoarthritis and elderly amputee gait. arch phys med rehabil. 1994; 75: 1094– 1099. https://doi.org/10.1016/0003-9993(94)90084-1 28.posnett j, franks pj. the costs of skin breakdown and ulceration in the uk. skin breakdown–the silent epidemic. hull: the smith and nephew foundation. 2007. 29.posnett j, franks p. the burden of chronic wounds in the uk. diabetic med 2008; 14: s7–s85. 30.datta d, vaidya sp, alsindi z. analyses of prosthetic episodes in trans-tibial amputees. prosthet orthot int. 1999; 23: 9–12. doi:10.3109/03093649909071605 31.nair a, hanspal rs, zahedi ms, saif m, fisher k. analyses of prosthetic episodes in lower limb amputees. . prosthet 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vacuum pressure settings . j prosthet orthot. 2010;22(4):252-256. doi: 10.1097/jpo.0b013e3181f903df 37.klute gk, berge js, biggs w, pongnumkul s, popovic z, curless b. vacuum-assisted socket suspension compared with pin suspension for lower extremity amputees: effect on fit, activity, and limb volume. arch phys med rehabil. 2011;92(10):1570-1575. https://doi.org/10.1016/j.apmr.2011.05.019 38.sanders je, harrison ds, myers tr, allyn kj. effects of elevated vacuum on in-socket residual limb fluid volume: case study results using bioimpedance analysis. j rehabil res dev. 2011;48(10):1231. doi:10.1682/jrrd.2010.11.0219 39.gerschutz mj, hayne ml, colvin jm, denune ja. dynamic effectiveness evaluation of elevated vacuum suspension. j prosthet orthot. 2015;27(4):161-5. doi: 10.1097/jpo.0000000000000077 40.darter bj, sinitski k, wilken jm. axial bone-socket displacement for persons with a traumatic transtibial amputation: the effect of elevated vacuum suspension at progressive body-weight loads. prosthet orthot int 2016; 40: 552–557. https://doi.org/10.1177/0309364615605372 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.1080/03093640601042554 https://doi.org/10.7888/juoeh.23.225 https://doi.org/10.1111/j.1468-3083.2006.01936.x https://doi.org/10.1111/j.1468-3083.2006.01936.x https://doi.org/10.1016/j.gaitpost.2010.05.003 https://doi.org/10.1016/0003-9993(94)90084-1 https://doi.org/10.1016/j.apmr.2007.11.054 https://doi.org/10.1080/03093640108726603 https://doi.org/10.1016/j.apmr.2011.05.019 https://doi.org/10.1177/0309364615605372 m mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.3. https://doi.org/10.33137/cpoj.v2i1.32723 8 open access perforated prosthetic liners volume 2, issue 1, article no.3, august 2019 https://jps.library.utoronto.ca/index.php/cpoj/index 41.beil tl, street gm, covey sj. interface pressures during ambulation using suction and vacuum-assisted prosthetic sockets. j rehabil res dev. 2002; 39: 693. 42.rink c, wernke mm, powell hm, gynawali s, schroeder rm, kim jy, et al. elevated vacuum suspension preserves residual-limb skin health in people with lowerlimb amputation: randomized clinical trial. j rehabil res dev. 2016;53(6). 1121–1132. doi:10.1682/jrrd.2015.07.0145 43.brunelli s, averna t, delusso m, et al. vacuum assisted socket system in transtibial amputees: clinical report. orthopädie-technik quarterly: english edition 2009; 2. 44.traballesi m, averna t, delussu as, brunelli s. transtibial prosthesization in large area of residual limb wound: is it possible? a case report. disabil rehabil assist technol. 2009;4(5):373-375. https://doi.org/10.1080/17483100903038568 45.traballesi m, delussu as, fusco a, iosa m, averna t, pellegrini r, et al. residual limb wounds or ulcers heal in transtibial amputees using an active suction socket system. a randomized controlled study. eur j phys rehabil med. 2012 dec 1;48(4):613-23. 46.hoskins rd, sutton ee, kinor d, schaeffer jm, fatone s. using vacuum-assisted suspension to manage residual limb wounds in persons with transtibial amputation: a case series. prosthet orthot int 2014; 38: 68–74. https://doi.org/10.1177/0309364613487547 47.philbeck jt, whittington kt, millsap mh, briones rb, wight dg, schroeder wj. the clinical and cost effectiveness of externally applied negative pressure wound therapy in the treatment of wounds in home healthcare medicare patients. ostomy wound manag. 1999;45(11):41-50. 48.huang c, leavitt t, bayer lr, orgill dp. effect of negative pressure wound therapy on wound healing. curr probl surg 2014; 51: 301–331. doi: 10.1067/j.cpsurg.2014.04.001 49.armstrong dg, lavery la, diabetic foot study consortium. negative pressure wound therapy after partial diabetic foot amputation: a multicentre, randomised controlled trial. lancet. 005;366(9498):1704-10. https://doi.org/10.1016/s0140-6736(05)67695-7 50.portnoy s, kristal a, gefen a, siev-ner i. outdoor dynamic subject-specific evaluation of internal stresses in the residual limb: hydraulic energy-stored prosthetic foot compared to conventional energy-stored prosthetic feet. gait posture. 2012;35(1):121-5. https://doi.org/10.1016/j.gaitpost.2011.08.021 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.1080/17483100903038568 https://doi.org/10.1177/0309364613487547 https://doi.org/10.1016/s0140-6736(05)67695-7 https://doi.org/10.1016/j.gaitpost.2011.08.021 pröbsting e, kannenberg a, blumentritt s. back pain and osteoarthritis as secondary disabilities of lower limb amputation. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32034 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) back pain and osteoarthritis as secondary disabilities of lower limb amputation eva pröbsting1*, andreas kannenberg2, siegmar blumentritt3 1 ottobock healthcare gmbh, germany. 2 otto bock healthcare lp, usa. 3 pfh göttingen, germany. * email: eva.proebsting@ottobock.de doi: https://doi.org/10.33137/cpoj.v1i2.32034 introduction long-term damages after lower extremity amputation have previously been analysed in three systematic reviews 5–7 showing that amputees have a higher risk for developing knee and hip osteoarthritis on the sound side. the altered gait pattern appears to increase the load on the sound side.1–3 this paper analysed the extent to which the above described assumption is supported by the scientific literature with specific focus on the risk of developing back pain and osteoarthritis in amputees. methods a systematic literature search (embase, medline, journal of prosthetics and orthotics database) was conducted for publications that had investigated changes caused by amputations. furthermore, the references of identified publications were also scanned for pertinent publications. all suitable articles were qualitatively analyzed and the available quantitative results were summarized. results the search identified 20 relevant studies,4-23 reporting back pain and 14 studies, 5-8, 11, 13, 20, 24-30 on osteoarthritis. the prevalence of back pain is increased for amputees in comparison to the able-bodied population. furthermore, amputees suffer more often from clinical signs of knee and hip osteoarthritis. nevertheless, the prevalence of radiographic signs is increased for the sound knee of the amputees. there are different reasons given in the literature for this increased risks. the altered gait 14, 17 and leg length discrepancies6, 11, 13, 20 seems to have a big influence on the back pain. for the increased prevalence of the osteoarthritis, these parameters 6, 11, 27, 28 as well as hopping 28 and standing without the prosthesis28 are contributing factors. figure 1. quantitative summary of the prevalence of back pain and arthritis. conclusion it may be possible to reduce the risks of back pain and osteoarthritis with novel prosthetic components and by optimising prosthetic fitting. on one hand, an optimised prosthesis will be used more regularly. on the other hand, it will be exposed to greater loads and therefore the load to the locomotor system could be distributed more evenly amongst both legs. both aspects would result in a more physiological loading of the locomotor system. significance it is often assumed that leg amputations result in a greater risk of degenerative changes to the locomotor system.24 furthermore in one-on-one interviews amputees report on their fear of these changes. therefore, this paper analysed the potential risk of various degenerative diseases in amputees. https://doi.org/10.33137/cpoj.v1i2.32034 mailto:eva.proebsting@ottobock.de https://doi.org/10.33137/cpoj.v1i2.32034 pröbsting e, kannenberg a, blumentritt s. back pain and osteoarthritis as secondary disabilities of lower limb amputation. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32034 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) references 1. gailey et al. review of secondary physical conditions associated with lower-limb amputation and long-term prosthesis use. j rehabil res dev; 2008;45(1):15-29. doi: 10.1682/jrrd.2006.11.0147 2. morgenroth dc, gellhorn ac, suri p. osteoarthritis in the disabled population: a mechanical perspective. pm r. 2012;4(5 suppl):s20-7. doi: 10.1016/j.pmrj.2012.01.003. 3. robbins et al. a review of the long-term health outcomes associated with 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doi:10.17305/bjbms.2006.3177 16. marshall et al. pain site and impairment in individuals with amputation pain. arch phys med rehabil. 2002;83(8):1116-9. doi: https://doi.org/10.1053/apmr.2002.33121 17. morgenroth et al. the relationship between lumbar spine kinematics during gait and low-back pain in transfemoral amputees. am j phys med rehabil. 2010;89(8):635-43. doi:10.1097/phm.0b013e3181e71d90 18. morgenroth et al. low-back pain in transfemoral amputees: is there a correlation with static or dynamic leglength discrepancy? am j phys med rehabil. 2009;88(2):10813. doi:10.1097/phm.0b013e318194fbbc 19. smith et al. phantom limb, residual limb, and back pain after lower extremity amputations. clin orthop relat res. 1999 apr;(361):29-38. 20. wilcke kh. unilateral leg amputation and its surgicalorthopedic sequelae. monatsschr unfallheilkd versicher versorg verkehrsmed. 1971;74(5):236-48. 21. melcer et al. a comparison of four-year health outcomes following combat amputation and limb salvage. plos one; 2017;12(2):e0173214.https://doi.org/10.1371/journal.pone.01 70569 22. devan h, seals r. vascular health in the ageing athlete. exp physiol, 2012;97.3; pp 305–310. doi: 10.1113/expphysiol.2011.058792 23. devan h et al. exploring factors influencing low back pain in people with nondysvascular lower limb amputation: a national survey. pm&r. 2017;9, 10, 949–959. doi: 10.1016/j.pmrj.2017.02.004 24. lemaire ed, fisher fr. osteoarthritis and elderly amputee gait. arch phys med rehabil. 1994;75(10):1094-9. 25. benichou c, wirotius jm. articular cartilage atrophy in lower limb amputees. arthritis rheum. 1982; 25,1, 80-82. 26. hungerford ds. early diagnosis of ischemic necrosis of the femoral head. johns hopkins med j. 1975;137:270–5. 27. kulkarni et al. association between amputation, arthritis and osteopenia in british male war veterans with major lower limb amputations. clin rehabil. 1998;12(4):348-53. doi:10.1191/026921598672393611 28. norvell et al. the prevalence of knee pain and symptomatic knee osteoarthritis among veteran traumatic amputees and nonamputees. arch phys med rehabil. 2005;86(3):487-93. doi:10.1016/j.apmr.2004.04.034 https://doi.org/10.33137/cpoj.v1i2.32034 https://doi.org/10.1053/apmr.2000.7583 https://doi.org/10.1080/09638280902810968 https://doi.org/10.1053/apmr.2001.21962 https://doi.org/10.1016/j.apmr.2005.03.031 https://doi.org/10.1191/0269215505cr819oa https://doi.org/10.17305/bjbms.2006.3177 https://doi.org/10.1053/apmr.2002.33121 https://doi.org/10.1097/phm.0b013e3181e71d90 https://doi.org/10.1097/phm.0b013e318194fbbc https://doi.org/10.1371/journal.pone.0170569 https://doi.org/10.1371/journal.pone.0170569 https://dx.doi.org/10.1113%2fexpphysiol.2011.058792 https://doi.org/10.1016/j.pmrj.2017.02.004 https://doi.org/10.1191/026921598672393611 https://doi.org/10.1016/j.apmr.2004.04.034 pröbsting e, kannenberg a, blumentritt s. back pain and osteoarthritis as secondary disabilities of lower limb amputation. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32034 3 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) 29. struyf et al. the prevalence of osteoarthritis of the intact hip and knee among traumatic leg amputees. arch phys med rehabil. 2009;90(3):440-6. doi: 10.1016/j.apmr.2008.08.220. 30. melzer i, yekutiel m, sukenik s. comparative study of osteoarthritis of the contralateral knee joint of male amputees who do and do not play volleyball. j rheumatol. 2001;28(1):169-72. disclosure eva pröbsting and andreas kannenberg are full time employees of the ottobock health care gmbh. https://doi.org/10.33137/cpoj.v1i2.32034 mileusnic m, rettinger l, highsmith m.j, hahn a. benefits of genium microprocessor controlled knee on ambulation, mobility, activities of daily living and quality of life: a systematic review. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018.doi: https://doi.org/10.33137/cpoj.v1i2.32033 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) benefits of genium microprocessor controlled knee on ambulation, mobility, activities of daily living and quality of life: a systematic review milana mileusnic1* , lena rettinger1, michael jason highsmith2, andreas hahn1 1 department of clinical research and services, otto bock healthcare products gmbh, austria. 2 extremity trauma & amputation center of excellence. u.s. department of veteran affairs, tampa, fl, usa. * email: milana.mileusnic@ottobock.com doi: https://doi.org/10.33137/cpoj.v1i2.32033 introduction several years ago, a new microprocessor controlled knee (mpk), genium, was introduced containing sensors, algorithms and technical solutions that enable a range of new functions to lower limb amputees. we conducted a systematic review to evaluate the effect of the knee on ambulation, mobility, activities of daily living (adls) and quality of life (qol). methods the systematic review was conducted according to the prisma guidelines and recommendations of the state-ofscience evidence report guidelines of the aaop. three reviewers conducted the quality assessment independently. results twelve articles were included in the review and reported of active subjects transitioning from c-leg to genium. the overall validity of the evidence was mostly medium and high (figure 1). common validity concerns included lack of blinding, incomplete reporting (fatigue & learning effect, attrition rate), effect size calculation, etc. nine articles focused on ambulation, in particular on level walking, stairs and ramps 1-9. biomechanical analysis reported of more physiological and symmetrical gait as well as reduction of loading and compensatory motion on sound side. four square step test, amputee mobility predictor and step activity derived functional level assessing the mobility were significantly improved6. four publications addressing adls reported of significant improvements with values closer to ablebodies subjects (i.e. domains upper-and lower-body strength, balance, coordination, endurance)6,9,11,12. two articles reported of significant effect of genium on qol6,10. figure 1. number and quality of evidence across categories. conclusion quality of evidence is predominantly moderate and high. genium resulted in more physiological gait, more evenly distributed loading and reduction in compensatory movements. significant improvements are reported in mobility, qol and especially safety and ability to conduct adls. significance additional benefits could be observed with genium in above knee amputees when compared to standard mpks. gait optimization could be relevant considering the longterm risk of secondary physical conditions in the prosthetic wearers. references 1. aldridge whitehead jm, et al. does a microprocessorcontrolled prosthetic knee affect stair ascent strategies in persons with transfemoral amputation? clin orthop relat res; 472, 3093-3101, 2014. doi:10.1007/s11999-014-3484-2 mailto:milana.mileusnic@ottobock.com https://doi.org/10.33137/cpoj.v1i2.32033 https://doi.org/10.1007/s11999-014-3484-2 mileusnic m, rettinger l, highsmith m.j, hahn a. benefits of genium microprocessor controlled knee on ambulation, mobility, activities of daily living and quality of life: a systematic review. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018.doi: https://doi.org/10.33137/cpoj.v1i2.32033 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) 2. bell em, et al. performance of conventional and x2® prosthetic knees during slope descent. clin biomech; 33, 2631, 2016. doi:10.1016/j.clinbiomech.2016.01.008 3. bellmann m, et al. immediate effects of a new microprocessor-controlled prosthetic knee joint: a comparative biomechanical evaluation. arch phys med rehab; 93, 541549, 2012. doi:10.1016/j.apmr.2011.10.017 4. bellmann m, et al. stair ascent with an innovative microprocessor-controlled exoprosthetic knee joint. biomed tech; 57, 435-444, 2012. doi:10.1515/bmt-2011-0029 5. lura dj et al. differences in knee flexion between the genium and c-leg microprocessor knees while walking on level ground and ramps. clin biomech; 30, 175-181, 2015. doi:10.1016/j.clinbiomech.2014.12.003 6. highsmith mj, et al. effects of the genium knee system on functional level, stair ambulation, perceptive and economic outcomes in transfemoral amputees. technol innov; 18, 139150, 2016. doi:10.21300/18.2-3.2016.139 7. highsmith mj, et al. effects of the genium microprocessor knee system on knee moment symmetry during hill walking. technol innov; 18, 151-157, 2016. doi: 10.21300/18.23.2016.151 8. highsmith mj, et al. short and mid-distance walking and posturography with a novel microprocessor knee. technol innov; 15, 359-368, 2014. doi: https://doi.org/10.3727/194982413x13844488879302 9. hahn a, et al. analysis of clinically important factors on the performance of advanced hydraulic, microprocessorcontrolled exo-prosthetic knee joints based on 899 trial fittings. medicine; 95(45), e5386, 2016. doi:10.1097/md.0000000000005386 10. highsmith mj, et al. perceived differences between the genium and the c-leg microprocessor prosthetic knees in prosthetic-related function and quality of life. technol innov; 15, 369375, 2014. doi: 10.3727/194982413x13844489091297 11. highsmith mj, et al. functional performance differences between the genium and c-leg prosthetic knees and intact knees. j rehabil res dev; 53, 753-766, 2016. doi: 10.1682/jrrd.2014.06.0149 12. kannenberg et al. activities of daily living: genium bionic prosthetic knee compared with c-leg. j prosthet orthot; 25, 110-117, 2013. doi: 10.1097/jpo.0b013e31829c221f disclosure m mileusnic, l rettinger and a hahn are affiliated with otto bock healthcare products. https://doi.org/10.1016/j.clinbiomech.2016.01.008 https://doi.org/10.1016/j.apmr.2011.10.017 https://doi.org/10.1515/bmt-2011-0029 https://doi.org/10.1016/j.clinbiomech.2014.12.003 https://doi.org/10.21300/18.2-3.2016.139 https://dx.doi.org/10.21300%2f18.2-3.2016.151 https://dx.doi.org/10.21300%2f18.2-3.2016.151 https://doi.org/10.3727/194982413x13844488879302 https://doi.org/10.1097/md.0000000000005386 https://doi.org/10.1682/jrrd.2014.06.0149 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 1 2020 research article köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://doi.org/10.33137/cpoj.v3i1.33768 1 köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 research article polycentric exoprosthetic knee joints – extent of shortening during swing phase köhler t.m1*, bellmann m1, blumentritt s2 1 clinical research and services, research biomechanics, ottobock se & co. kgaa, göttingen, germany. 2 private university of applied science, göttingen, germany. introduction tripping is a safety risk for amputees and it is mainly affected by ground clearance during swing phase. in mid– swing, the toe is at the minimum distance to the ground while the shank rotates forward.1,2 to compensate for a lack of ground clearance, transfemoral amputees often perform compensatory movements including plantar flexion of the intact ankle during prosthetic swing (vaulting), lifting the hip on the prosthetic side during prosthetic swing (hip hiking), and swinging the prosthesis forward in an arc by abducting the hip early in swing and then adducting the hip late in swing (circumduction). these gait abnormalities reduce walking efficiency and are therefore undesirable.1-4 during prosthetic alignment, the length of the prosthesis can be reduced when compared to the intact limb and this might result in increased ground clearance during walking. however, this intervention can lead to other compensatory movements,5 reduced walking efficiency6 and lower back pain.7 therefore, a prosthesis that provides a technical solution for ensuring adequate ground clearance during swing phase on the prosthetic side is desirable. sockets with vacuum suspension can minimize longitudinal movement (pistoning) between the socket and limb8 and thus reduce the functional elongation of the prosthesis. prosthetic feet generating ankle dorsiflexion during swing phase showed more ground clearance compared to conventional energy storing and returning feet.9,10 open access volume 3, issue 1, article no.5. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: an often assumed advantage of polycentric knee joints compared to monocentric ones is the improved ground clearance during swing phase due to the geometric shortening of the lower leg segment (lls). objective: to investigate whether polycentric knee joints considerably improve ground clearance and to evaluate the influence of prosthetic alignment on the extent of ground clearance. methodology: 11 polycentric and 2 monocentric knee joints were attached to a rigid, stationary testing device. shortening of the lls and the resulting ground clearance during knee flexion were measured. prosthetic components were mounted at the same height and the anterior-posterior position was in accordance with the manufacturer's alignment recommendations. findings: shortening of up to 14.7 (sd=0.0) mm at the instance of minimal ground clearance during swing phase was measured. one knee joint elongated by 4.4 (sd=0.0) mm. measurements of the ground clearance demonstrated differences up to 25.4 (sd=0.0) mm. one monocentric knee joint provided more ground clearance when compared to 8 of the polycentric knee joints investigated. conclusion: only some polycentric knee joints shorten appreciably during swing phase. with an optimized prosthetic alignment and a well-designed swing phase control, a monocentric knee joint may generate greater ground clearance compared to a polycentric knee joint. article info received: february 14, 2020 accepted: july 20, 2020 published: july 29, 2020 citation köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj. v3i1.33768 keywords amputation, ground clearance, knee joint, polycentric, prosthesis, limb loss, rehabilitation. * corresponding author: thomas maximilian köhler, msc ottobock: hermann-rein-straße 2a, 37075, göttingen. e-mail: thomasmaximilian.koehler@ottobock.de orcid: https://orcid.org/0000-0002-5063-121x https://doi.org/10.33137/cpoj.v3i1.33768 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i1.33768 https://doi.org/10.33137/cpoj.v3i1.33768 file:///d:/cpoj%20submitted%20articles/accepted-completed/33-thirty%20three%20article-cpoj-4t-2020-ottobook-kohler/article%20proof/thomasmaximilian.koehler@ottobock.de 2 köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 issn: 2561-987x swing shortening in polycentric knee joints köhler et al. 2020 cpoj polycentric knee joints also showed more ground clearance during swing phase when compared to monocentric knee joints.1,11 due to their technical design, prosthetic knee components can be divided into two main categories: monocentric and polycentric knee joints. monocentric knee joints have a single center of rotation (cr) that is independent of the knee flexion angle. in polycentric knee joints, the upper and lower parts of the knee joint are usually connected via a four-bar linkage mechanism. they rotate around an instantaneous center of rotation (icr), which is dependent upon the knee flexion angle. the icr results from the intersection of the longitudinal axes of the anterior and the posterior linkages. depending on the specific linkage mechanism, the icr is usually located outside of the knee joint construction itself.12consequently, there is a high degree of stance phase safety provided at heel strike since a fully extended knee joint results in an icr that is located posterior to the knee joint and this is posterior to the vector of the ground reaction force. for patients with knee disarticulation or long transfemoral residual limbs, polycentric knee joints are preferred from a cosmetic point of view when seated, due to the minimized protrusion at the distal end of the socket in a flexed knee position.11 as an additional advantage, the shortening of the shank during swing phase or virtual ankle dorsiflexion is often stated.1, 11, 13 due to their design, polycentric knee joints are able to generate greater ground clearance in a flexed knee position compared to monocentric ones based on this shortening effect. hence, in a study from 1996, ground clearance values were 9-32 mm higher for polycentric joints.11 another study reported an average of 22 mm more ground clearance for the investigated polycentric knee joints.1 currently, there is a larger variation in the length and orientation of the linkages in polycentric knee joints than in the formerly reported studies. consequently, for the knee joints investigated in this study shortening effects of less than the formerly reported 9 mm were expected. objective the aim of this study was to investigate whether polycentric knee joints generally show a marked shortening of the lower leg segment during prosthetic swing phase resulting in a clear advantage for patients regarding tripping. furthermore, the influence of prosthetic alignment with regards to ground clearance was also examined. methodology knee joints in this study, 11 polycentric knee joints were investigated: the 3r46/3r55, 3r60, 3r106 (ottobock se & co. kgaa, duderstadt, germany), total knee 2000, ohp3/khp3, oh5/kh5 (össur, reykjavik, iceland), tgk-4p01p, tk-4p00s (teh lin, taipei, taiwan), jt22 (uniprox, zeulenroda, germany), kx06 (blatchford, basingstoke, united kingdom) and allux (nabtesco, tokyo, japan). the monocentric knee joints 3r45/3r95 and c-leg (ottobock se & co. kgaa, duderstadt, germany) were also examined. except for the 3r60 and total knee 2000, each of the polycentric knee joints utilizes a 4-bar linkage system. the fifth axis of the 3r60 only affects stance phase. therefore, the 3r60 is effectively a 4-bar linkage knee joint during swing phase. the total knee uses a 7 axis linkage mechanism and all of the axes are involved during swing phase motion (figure 1). figure 1: polycentric and monocentric knee joints investigated with schematic illustration of the icr respectively (scaling is not uniform between the knee joints), *according to van de veen pg ,2001.14 3r60 3r46/3r55 kx06 ohp3/khp3 oh5/kh5 total knee* jt22 3r106 c-leg 3 c-leg 4 allux tgk-4p01p tk-4p00s 3r45/3r95 https://doi.org/10.33137/cpoj.v3i1.33768 3 köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 issn: 2561-987x swing shortening in polycentric knee joints köhler et al. 2020 cpoj prosthetic alignment bench alignment of the prosthesis was performed using a l.a.s.a.r assembly (ottobock se & co. kgaa, duderstadt, germany). for each alignment, a trias foot (ottobock se & co. kgaa, duderstadt, germany) with a length of 260 mm and an effective heel height of 10 mm was used. the 7e7 (otto bock, duderstadt, germany) was utilized as a hip joint. the knee joint was adjusted to a height of 520 mm and the 7e7 to 900 mm. the hip joint axis was located 10 mm anterior to the reference line since the physiological hip center of rotation is located approximately 10 mm anterior to the greater trochanter and this is typically used as the reference point for the prosthetic socket anterior-posterior position (figure 2). the length of the prosthesis was approximated according to an average person (male, 1.80 m) based on anthropomorphic data. the a-p (anterior-posterior) position of each knee component and foot were aligned according to the manufacturer’s instructions for the individual knee joint (table 1). following these recommendations, the alignments should provide realistic data for each specific knee joint investigated in this study. the allux and c-leg were tested according to their recommended alignment. subsequently, these knee joints were re-tested with the others respective recommended alignment to observe the effect of alignment differences on ground clearance without the possible influence of shortening effects. table 1. alignment position of prosthetic knee joints investigated. knee joint position foot position alignment reference point* [mm] anterior + / posterior allux fp 1 / fp 2 0/0 kx06 fp 1 0 total knee fp 2 +11** ohp3/khp3 fp 2 0 oh5/kh5 fp 2 0 tgk-4p01p fp 2 0 tk-4p00s fp 2 0 jt22 fp 1 -25 3r46/3r55 fp 1 -10 3r60 fp 1 0 3r106 fp 1 0 3r45/3r95 fp 1 -15 c-leg fp 1 / fp 1 / fp 2 +5 / 0 / 0 *upper anterior axis for polycentric knee joints, knee rotation axis for monocentric knee joints **offset between reference axis defined by the manufacturer (aligned on the alignment reference line) and upper anterior axis is approximately 11 mm. each foot was positioned as follows: • foot position 1 (fp 1): the middle of the foot is positioned 30 mm anterior to the alignment reference line • foot position 2 (fp 2): the alignment reference line divides the foot into 1/3 rear foot and 2/3 forefoot in order to ensure that the motion only occurred in the sagittal plane, the axes of rotation for the hip and knee as well as the distal surface of the foot were all aligned perpendicular to the sagittal plane for all test setups. experimental setup the test prosthesis was connected via the proximal part of the 7e7 joint to a stationary device. this configuration allowed a step-less adjustment of the hip flexion angle. the position of the hip axis of rotation was stationary. the study from winter cites an average hip angle of 23° at the instance of minimal ground clearance while walking at a selfselected, medium walking speed.15 in this study, four hip flexion angles were evaluated: 15°, 20°, 25° and 30° (angle from vertical). this range should cover the potential hip flexion of a transfemoral amputee at the instance of minimum ground clearance during swing phase (figure 3). due to different pyramid adapter positions for each knee joint, the resulting inclination of the tube adapter between hip and knee joint varies during bench alignment. starting from the individual inclinations of the tube adapter, the hip joint was flexed by the respective angles investigated. this ensures identical effective hip flexion angles for all investigated knee joints (figure 2). measuring system kinematic parameters were measured via an optoelectronic 12-camera motion capture system at a sampling rate of 200 hz (vicon bonita b10, vicon peak, oxford, united kingdom). four retro-reflective markers were attached to the prosthesis: hip joint axis, knee joint axis (polycentric: upper anterior axis), lateral ankle adapter screw, big toe (hallux) (figure 2). 3d trajectories (x,y,z) of the markers were captured with an accuracy of 0.5 mm.16 experimental procedure the specifically defined hip angle was adjusted prior to each measurement. the knee joint was flexed and extended manually from the fully extended position to a knee flexion angle of approximately 90° and then back into full extension six times during the measurement (six motion cycles). data analysis minimum ground clearance was defined as the event when the z-component of the big toe marker reached its minimum. shortening of the lower leg segment was defined by the difference of the distance between the knee marker and the https://doi.org/10.33137/cpoj.v3i1.33768 4 köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 issn: 2561-987x swing shortening in polycentric knee joints köhler et al. 2020 cpoj big toe marker at full knee extension, and at the instant of minimal ground clearance. the distances were calculated within the sagittal plane, via the xzcoordinates (figure 2). this definition was used because it considers the possible virtual ankle dorsiflexion that was previously reported.1, 11 all results are described as mean values over six motion cycles. figure 2: schematic illustration of: (a) prosthetic alignment. (b) experimental setup with knee joint in full extension, (i) hip flexion angle (individual tube inclination was considered), (ii) distance between knee (extended) and big toe marker. (c) experimental setup when knee joint is flexed, (iii) distance between knee (flexed) and big toe marker, (iv) minimum ground clearance. figure 3: (a) transfemoral amputee during level ground walking (examplethe patient has given written informed consent for use of the picture). (b) typical mean sagittal hip angle of transfemoral amputees while walking on level ground (n=6).17 red area indicates assumed range where minimum ground clearance occurs. -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 0 10 20 30 40 50 60 70 80 90 100 s a g it ta l h ip a n g le [ ] t [%gait cycle] ba b hip-axis 900 mm knee-axis 520 mm heel 10 mm shank shortening (ii)-(iv) hip-axis ap +10 mm https://doi.org/10.33137/cpoj.v3i1.33768 5 köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 issn: 2561-987x swing shortening in polycentric knee joints köhler et al. 2020 cpoj validation of the measurement method due to minimal changes in the prosthetic alignment, setup alignment and marker placement, deviations in the investigated parameters might occur. to validate the reproducibility of the measurement method, the previously described procedure (1. prosthetic alignment, 2. experimental setup and application of reflective marker, 3. experimental procedure) was repeated 3 times (including 15 motion cycles each) for one representative hip flexion position (25°) involving the 3r60 and c-leg. • evaluation of the inter-test reliability: for each repetition, the mean was calculated for lower leg shortening and minimum ground clearance. an anova based reliability measure was calculated with a tolerance threshold of sd=1.5 mm, given the following formula: o variance explained by threshold, assuming an equal distribution of means 𝑥�̅� over the range of their average �̅� ±1.5 mm: 𝑉𝑎𝑟𝑡ℎ𝑟𝑒𝑠ℎ𝑜𝑙𝑑 = 1 12 (1.5 − (−1.5))2 = 0.75 o reliability = 𝑚𝑖𝑛 [1; 1 − 𝑉𝑎𝑟𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑉𝑎𝑟𝑡𝑜𝑡𝑎𝑙 + 𝑉𝑎𝑟𝑡ℎ𝑟𝑒𝑠ℎ𝑜𝑙𝑑 𝑉𝑎𝑟𝑡𝑜𝑡𝑎𝑙 ] with 𝑉𝑎𝑟𝑡𝑜𝑡𝑎𝑙 the total variance and 𝑉𝑎𝑟𝑏𝑒𝑡𝑤𝑒𝑒𝑛 the variance of the means. subsequent ranges of the 3 mean values were calculated respectively: o minimum ground clearance: 1.6 mm (3r60) and 0.6 mm (c-leg) o lower leg shortening: 2.2 mm (3r60) and 0.3 mm (c-leg) with a maximum range of 2.2 mm measured, the authors evaluate the measurement reliability as adequate for the statements made in this study (reliability coefficients 0.851). • evaluation of the intra-test reliability: given the data from 15 motion cycles, the range and precision (half-length of the confidence interval for the mean) was calculated for each repetition, assuming that the point estimations of mean and variance were based on only 6 measurements. this assumption allowed an estimation of the expected precision when using only 6 motion cycles instead of 15. the resulting maximum range (r) and minimum precision (pr) were: o minimum ground clearance: r = 0.4 mm, pr = 0.13 mm (3r60); r = 0.5 mm, pr = 0.13 mm (c-leg) o lower leg shortening: r = 0.6 mm, pr = 0.15 mm(3r60); r = 0.4 mm, pr = 0.13 mm (c-leg) the evaluation of the intra-test reliability showed that the rigid stationary device offers a constant motion of the prosthesis (deviation for measured parameters approximately sd=0.3 mm). thus, mean values over six motion cycles seem to provide sufficient precision (0.060.15 mm). results lower leg shortening except for the total knee and allux, each polycentric knee joint generated a shortening of the lower leg segment during minimal ground clearance for all hip angles investigated. shortening of up to 14.7 (sd=0.0) mm was measured for the 3r46/3r55. the total knee elongated over all investigated hip angles with a maximum of 4.4 (sd=0.0) mm at 30° hip flexion. the allux knee joint elongated (max. 0.5 mm) at a hip flexion angle of 25° and 30°. the shortening tends to decrease with increasing hip flexion angles for all joints expect for the kx06 and 3r46/3r55 (figure 4). minimum ground clearance when comparing the results of ground clearances, the minimum value measured at each hip flexion angle was set to 0 mm. the lowest ground clearance was identified with the jt22 for all hip flexion angles. in comparison, the 3r60 provides up to 25.4 (sd=0.0) mm greater ground clearance. at 15° hip flexion, 6 polycentric knee joints showed lower ground clearance than the c-leg (12 mm with fp 1 / knee +5). at 25° and 30° hip flexion, 8 polycentric knee joints demonstrated lower ground clearance than this monocentric knee joint (figure 4). comparison of different alignment methods a comparison of different alignment methods with regards to toe clearance was conducted for the allux and c-leg. at 15° hip flexion, the allux showed 4.1 mm greater ground clearance with the fp 1 than with the fp 2 and 4.3 mm greater ground clearance at 30° hip flexion, respectively. with the c-leg, ground clearance at 15° hip flexion was 6.6 mm greater with the fp 1 / knee +5 than with the fp 2 / knee 0 and 8.2 mm greater at 30° hip flexion, respectively (figure 4). discussion the aim of this study was to investigate whether polycentric knee joints provide a substantial shortening of the lower leg segment during swing phase. the results indicate that this is not valid for each polycentric design. due to the individual length and orientation of the linkages of each polycentric knee joint investigated a large variation of shortening effects were observed. as mentioned by anand et al.18, a higher icr seems to result in higher ground clearance.19 this should be considered in the development of the geometric design of a polycentric knee joint.18 however, this correlation could not be observed. polycentric knee joints https://doi.org/10.33137/cpoj.v3i1.33768 6 köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 issn: 2561-987x swing shortening in polycentric knee joints köhler et al. 2020 cpoj with a more proximally located icr (figure 1: total knee, jt22, 3r106) demonstrate lower leg shortening of up to 6.0 (sd=0.0 mm) or even elongation of up to 4.4 (sd=0.0) mm. the 3 polycentric knee joints demonstrating the greatest shortening of the lower leg segment (figure 1: kx06, 3r60, 3r46/3r55) share other similarities (figure 3, table 2): the posterior linkage is relatively long and tilted anteriorly. the icr is (compared to the total knee, jt22, 3r106) more distally and more anteriorly located (close to the longitudinal axis of the knee joint). these knee joints reached 7.0 (sd=0.0) mm up to 14.7 (sd=0.0) mm lower leg shortening. furthermore, the impact of the prosthetic alignment on ground clearance was considerable. thus, some of the knee joints generated relatively minor ground clearance even though they shortened to a large extent of up to 14.7 (sd=0.0) mm. -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 total knee c-leg (fp 1 / knee 0) c-leg (fp 1 / knee +5) 3r45/3r95 c-leg (fp 2 / knee 0) tgk-4p01p allux (fp 1) allux (fp 2) tk-4p00s 3r106 oh5/kh5 jt22 kx06 ohp3/khp3 3r60 3r46/3r55 shortening/ground clearance [mm] a -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 total knee c-leg (fp 1 / knee 0) c-leg (fp 1 / knee +5) 3r45/3r95 c-leg (fp 2 / knee 0) tgk-4p01p allux (fp 1) allux (fp 2) tk-4p00s 3r106 oh5/kh5 jt22 kx06 ohp3/khp3 3r60 3r46/3r55 shortening/ground clearance [mm] b -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 total knee c-leg (fp 1 / knee 0) c-leg (fp 1 / knee +5) 3r45/3r95 c-leg (fp 2 / knee 0) tgk-4p01p allux (fp 1) allux (fp 2) tk-4p00s 3r106 oh5/kh5 jt22 kx06 ohp3/khp3 3r60 3r46/3r55 shortening/ground clearance [mm] c -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 total knee c-leg (fp 1 / knee 0) c-leg (fp 1 / knee +5) 3r45/3r95 c-leg (fp 2 / knee 0) tgk-4p01p allux (fp 1) allux (fp 2) tk-4p00s 3r106 oh5/kh5 jt22 kx06 ohp3/khp3 3r60 3r46/3r55 shortening/ground clearance [mm] d figure 4: shortening of the lower leg segment (black) and ground clearance (grey) at the instance of minimal ground clearance (a) 15°, (b) 20°, (c) 25° and (d) 30° hip flexion; mean with standard deviation. shortening of the lower leg segment ground clearance https://doi.org/10.33137/cpoj.v3i1.33768 7 köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 issn: 2561-987x swing shortening in polycentric knee joints köhler et al. 2020 cpoj the a-p position of the knee joint caused by the alignment affects the ground clearance in two ways: the more posterior the knee joint, the 1. closer the knee center of rotation is to the ground during hip flexion. this effect increases with increasing hip flexion angles due to the more distally located trajectory of the knee reference point (figure 5 a-b). 2. greater the distance between the knee center of rotation and the big toe and this results in a longer prosthesis at the instance of minimal ground clearance (figure 5 c-d). this substantive alignment effect can be clearly seen with the 3r95 monocentric knee joint which is aligned 20 mm more posteriorly than the monocentric c-leg (fp 1 / knee +5) and this results in 16.5 mm less ground clearance at 30° hip flexion. thus, ground clearance during swing phase is enhanced when the knee joint is placed in a more anterior position. as an example, one monocentric knee joint (c-leg, fp 1 / knee +5) generated greater ground clearance then up to 8 polycentric knee joints due to its specific alignment depending on hip flexion angle. table 2: evaluation of the geometric design of the polycentric knee joints investigated based on figure 1 (visual comparison of proportions). knee joint icr height* icr a-p position length anterior linkage length posterior linkage tilt anterior linkage tilt posterior linkage lls (25°) [mm] total knee high posterior short short backward backward -3.9 (sd=0.1) allux (fp 2) low centered short short backward forward 0.0 (sd=0.0) tgk-4p01p low posterior short short backward backward 0.3 (sd=0.1) 3r106 high posterior long short backward backward 2.8 (sd=0.0) tk-4p00s medium posterior short short backward backward 3.7 (sd=0.0) oh5/kh5 below knee joint anterior long short backward backward 4.6 (sd=0.1) jt22 high posterior medium short backward backward 5.2 (sd=0.2) ohp3/khp3 below knee joint anterior long short backward backward 7.4 (sd=0.2) kx06 low centered long medium backward forward 7.4 (sd=0.0) 3r60 medium centered long medium backward forward 10.8 (sd=0.1) 3r46/3r55 medium centered long long backward forward 14.2 (sd=0.1) *high-low: icr above knee joint; high: more proximally located, low: more distally located. abbreviations: icr instantaneous center of rotation, a-p anterior posterior, lls lower leg shortening figure 5: effect of a-p positioning of the knee and foot components (a) experimental set up, (b) schematic diagram of the effect of a-p positioning of the knee, (i) hip flexion angle, (ii) gain of ground clearance, (iii) loss of ground clearance, (c) prosthetic alignment, (d) schematic diagram of shortening and elongation of the shank, respectively, (iv) depending on the position of the knee and foot. knee ap position foot ap position https://doi.org/10.33137/cpoj.v3i1.33768 8 köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 issn: 2561-987x swing shortening in polycentric knee joints köhler et al. 2020 cpoj additionally, the effect of the foot position was investigated and resulted in the following observation: the more anterior the position of the foot, the longer the forefoot and the longer the distance between the knee center of rotation and the big toe. hence, ground clearance decreases during swing with a more anteriorly positioned foot (figure 5 c-d). as a conclusion, the fp 1 exhibited a considerable advantage over the fp 2 for the two knee joints that were investigated with these two alignment methods (c-leg, allux). in this study the extent of geometric shortening of the lower leg segment with different polycentric knee joints, as well as the impact of prosthetic alignment on the resulting ground clearance was investigated. another potential aspect regarding the resulting ground clearance, not being investigated in this study, is the property of the swing phase control of the prosthetic knee joint. based on the investigation of winter, small differences in knee flexion angle considerably affect ground clearance. 1.4° difference in the knee flexion angle resulted in a difference of 4.5 mm ground clearance, seen in non-amputees.15 depending on the individual swing phase control (appropriate adjustment of the swing flexion and extension resistance) of the prosthetic knee joint, the knee angle progression during swing phase can vary significantly.20,21 thus, the swing phase control might have an influence on the resulting ground clearance. therefore, further experiments with the knee joints presented in this study are suggested to clarify this additional aspect. limitations the prosthetic and experimental setup as well as the marker positioning was adjusted with the greatest care. however, minimal deviations might occur, as seen in the validation of the measurement method. due to these effects, nonrealistic shortenings of the shank were measured even for monocentric knee joints (e.g. c-leg 4, (sd=0.4) mm). the authors assume an overall accuracy of sd=1.1 mm for the investigated parameters. this assumption is based on the validation of the entire measurement method. nevertheless, this accuracy is sufficient for the statements that were made in this study. conclusion in summary, not all polycentric knee joints shorten appreciably at the instant when a stumble might occur. thus, the previously stated functional advantage of greater ground clearance for patients must be reconsidered. a slightly more anterior position of the knee joint or a more posterior position of the foot can compensate for or even exceed the extent of the geometric shortening of the shank of some polycentric knee joints. acknowledgements the authors thank prof. dr. dieter rosenbaum, greg schneider, lena uhlenberg and aideen curran for their valuable contribution to the preparation of this article. declaration of conflicting interests mr. thomas maximilian köhler and dr. malte bellmann are employees of ottobock se & co. kgaa. author contribution each of the authors concurs with the content in the final manuscript. • mr. thomas maximilian köhler, msc: study design, execution of the gait lab measurements, data analysis and interpretation, drafting of the article orcid: https://orcid.org/0000-0002-5063-121x • dr. malte bellmann: study design, execution of the gait lab measurements, data analysis and interpretation, drafting of the article. orcid: https://orcid.org/0000-0002-5002-9245 • prof. dr. siegmar blumentritt: drafting of the article. orcid: https://orcid.org/0000-0003-4190-6098 sources of support this research received no specific grant from any agency in the public, commercial or not-for-profit sectors. references 1.sensinger jw, intawachirarat n, gard sa. contribution of prosthetic knee and ankle mechanisms to swing-phase foot clearance. ieee trans neural syst rehabil eng. 2013; 21(1):74– 80. doi: 10.1109/tnsre.2012.2224885 2.villa c, loiret i, langlois k, bonnet x, lavaste f, fodé p et al. cross-slope and level walking strategies during swing in individuals with lower limb amputation. arch phys med rehabil. 2017; 98(6):1149–57. doi:10.1016/j.apmr.2016.10.007 3.drevelle x, villa c, bonnet x, loiret i, fodé p, pillet h. vaulting quantification during level walking of transfemoral amputees. clin biomech (bristol, avon). 2014; 29(6):679–83. doi: 10.1016/ j.clinbiomech.2014.04.006 4.michaud sb, gard sa, childress ds. a preliminary investigation of pelvic obliquity patterns during gait in persons with transtibial and transfemoral amputation. j rehabil res dev. 2000; 37(1):1–10. 5.walsh m, connolly p, jenkinson a, o’brien t. leg length discrepancy—an experimental study of compensatory changes in three dimensions using gait analysis. gait posture. 2000; 12(2):156–61. doi: 10.1016/s0966-6362(00)00067-9 6.song km, halliday se, little dg. the effect of limb-length discrepancy on gait. j bone joint surg am. 1997; 79(11):1690–8. https://doi.org/10.33137/cpoj.v3i1.33768 https://orcid.org/0000-0002-5063-121x https://orcid.org/0000-0002-5002-9245 https://orcid.org/0000-0003-4190-6098 9 köhler t.m, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.5. https://doi.org/10.33137/cpoj.v3i1.33768 issn: 2561-987x swing shortening in polycentric knee joints köhler et al. 2020 cpoj 7.defrin r, ben benyamin s, aldubi rd, pick cg. conservative correction of leg-length discrepancies of 10mm or less for the relief of chronic low back pain. arch phys med rehabil. 2005; 86(11):2075–80. doi:10.1016/j.apmr.2005.06.012 8.klute gk, berge js, biggs w, pongnumkul s, popovic z, curless b. vacuum-assisted socket suspension compared with pin suspension for lower extremity amputees: effect on fit, activity, and limb volume. arch phys med rehabil. 2011; 92(10):1570–5. doi: 10.1016/j.apmr.2011.05.019 9.johnson l, asha ar de, munjal r, kulkarni j, buckley jg. toe clearance when walking in people with unilateral transtibial amputation: effects of passive hydraulic ankle. j rehabil res dev. 2014; 51(3):429–37. doi: 10.1682/jrrd.2013.05.0126 10.rosenblatt nj, bauer a, rotter d, grabiner md. active dorsiflexing prostheses may reduce trip-related fall risk in people with transtibial amputation. j rehabil res dev. 2014; 51(8):1229– 42. doi: 10.1682/jrrd.2014.01.0031 11.gard sa, childress ds, uellendahl je. the influence of fourbar linkage knees on prosthetic swing-phase floor clearance. j prosthet orthot. 1996; 8(2):34–40. 12.radcliffe cw. four-bar linkage prosthetic knee mechanisms: kinematics, alignment and prescription criteria. prosthet orthot int, 1994; 18(3):159–73. 13.lechler k, and kristjansson k. the importance of additional mid swing toe clearance for amputees. can prosthet orthot j. 2018;1,2. doi: 10.33137/cpoj.v1i2.30813 14. van de veen pg, above-knee prostheses [internet]. enschede 2001. [cited 2020, july 20]. available from: https://www.worldcat.org/title/above-knee-prosthesistechnology/oclc/48194801 15.winter d. foot trajectory in human gait: a precise and multifactorial motor control task. phys ther. 1992; 71(1):45–53. doi:10.1093/ptj/72.1.45 16.vicon motion systems. technical manual: bonita. [internet]. oxford: united kingdom. [cited 2020 july 20]. available from: https://est-kl.com/images/pdf/vicon/bonita_optical.pdf 17.bellmann m, köhler tm, schmalz t. comparative biomechanical evaluation of two technologically different microprocessor-controlled prosthetic knee joints in safety-relevant daily-life situations. biomed tech. 2018; 64(4). doi: 10.1515/bmt2018-0026 18. anand ts, sujatha s. a method for performance comparison of polycentric knees and its application to the design of a knee for developing countries. prosthet orthot int. 2017; 42(4): 402-411. doi: 10.1177/0309364616652017 19.iso 10328:2006 e. prosthetics – structural testing of lower limb prostheses – requirements and test methods. [internet], [cited 2020 july 20]. available from: https://www.iso.org/standard/38708.html 20.bellmann m, schmalz t, blumentritt s. comparative biomechanical analysis of current microprocessor-controlled prosthetic knee joints. arch phys med rehabil. 2010; 91(4):644-52. doi: 10.1016/j.apmr.2009.12.014 21.thiele j, schöllig c, bellmann m, kraft m. designs and performance of three new microprocessor-controlled knee joints. biomed tech. 2019; 64(1):119–126. doi: 10.1515/bmt-2017-0053 https://doi.org/10.33137/cpoj.v3i1.33768 https://www.worldcat.org/title/above-knee-prosthesis-technology/oclc/48194801 https://www.worldcat.org/title/above-knee-prosthesis-technology/oclc/48194801 https://est-kl.com/images/pdf/vicon/bonita_optical.pdf https://www.iso.org/standard/38708.html brown s, trexler g. case study: thermoplastic scapulothoracic orthosis for treatment of winging scapula. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32043 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) case study: thermoplastic scapulothoracic orthosis for treatment of winging scapula steven brown*, gary trexler university of oklahoma health science center, oklahoma city, oklahoma, usa. *e-mail: steven-brown@ouhsc.edu doi: https://doi.org/10.33137/cpoj.v1i2.32043 introduction winging scapula is a rare condition that can be painful and debilitating to the upper extremity involved1. this condition can affect the functional ability of the upper extremity, resulting in loss of range of motion, decreased power, and pain.1 the purpose of this study was to introduce and determine the clinical applicability of a custom thermoplastic scapulothoracic orthosis to aid in management of winging scapula. the thermoplastic scapulothoracic orthosis offers total contact and provides anterior-posterior compressive forces to stabilize the winging scapula. this design provides a semi-rigid structure that is lightweight and allows user adjustability. the study highlights the potential applicability of the custom thermoplastic scapulothoracic orthosis in the categories of pain, active range of motion at the shoulder, and overall self-reported activities of daily living. methods a 56-year-old male who experienced left winging scapula secondary to a traumatic work injury was evaluated and treated in the clinic. a custom scapulothoracic orthosis was designed, fabricated, and fit to the patient as part of his rehabilitation process. prior to the fitting of the orthosis his pain levels were verbally discussed and the subject rated his pain on a scale of 0 to 10, with 0 = no pain, and 10 = very much pain. also, active range of motion was measured using a goniometer. after a six-week accommodation period these tests occurred again while wearing the orthosis and were compared. the subject stated that his pain levels had decreased his activities of daily living and caused him to live a more sedentary lifestyle. results the subject wore the scapulothoracic orthosis for approximately eight hours per day for six weeks. selfreported pain was reduced in resting activity from 8/10 to 3/10. it was also reduced in glenohumeral flexion activities from 10/10 to 4/10. active range of motion at the shoulder is listed in table 1. range of motion increased during shoulder flexion 106%, abduction 63%, internal rotation 55%, and external rotation 61%. the subject’s winging scapula was visually reduced, but not completely eliminated. the subject verbally reported that the orthosis made activities such as cooking, typing on a computer, and brushing his hair/teeth more tolerable. table 1. active range of motion at the shoulder, with no orthosis and while wearing orthosis. conclusion the use of a thermoplastic scapulothoracic orthosis in treatment of winging scapula secondary to a traumatic work injury had positive outcomes, including a reduction in pain levels, an increase in active range of motion and a reduction in visual scapular winging. the subject stated that with use of the orthosis, his activities of daily living increased. a limitation of the study includes the absence of an objective measurement technique used to measure scapular winging. significance the thermoplastic scapulothoracic orthosis is a viable option for treatment of winging scapula when surgery is not indicated or is not an option. references 1. martin rm., fish de. scapular winging: anatomical review, diagnosis, and treatments. curr rev musculoskelet med. 2008; 1(1), 1–11. doi: 10.1007/s12178-007-9000-5 mailto:steven-brown@ouhsc.edu https://doi.org/10.33137/cpoj.v1i2.32043 https://dx.doi.org/10.1007%2fs12178-007-9000-5 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no 5, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30354 research article volume 1, issue 1 2 0 1 8 research article issn: 2561-987x all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x https://doi.org/10.33137/cpoj.v1i1.30354 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no 5, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30354 research article a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission buis a1*, guarato f2, law j1, ralston z1, & courtney a3 1 department of biomedical engineering, university of strathclyde, glasgow, scotland, uk. 2 department of electronic and electric engineering, university of strathclyde, glasgow, scotland. uk. 3 the london orthotic consultancy ltd, kingston-upon-thames, greater london, england, uk. *corresponding author dr. arjan buis, department of biomedical engineering, university of strathclyde, wolfson centre, 106 rottenrow, glasgow, g4 0nw, scotland, uk. orcid number: https://orcid.org/0000-0003-3947-293x email: arjan.buis@strath.ac.uk doi: https://doi.org/10.33137/cpoj.v1i1.30354 cpoj editors-in-chief dr. silvia u raschke, british columbia institute of technology (bcit), canada dr. thorvaldur ingvarsson, orthopaedic surgeon, university of iceland, iceland abstract background: background: acoustic emission from structures subject to external loads can be monitored to detect internal damage before destruction occurs. it is hypothesised that deformation of soft tissue will emit acoustic signals which may aid early detection of deep tissue injury, particularly in the lower limb amputee population. no previous studies have applied this method to biological soft tissue. objective: to determine if skeletal muscle tissue produced measurable acoustic emission during dynamic tensile loading with the aim to establish a reliable biomarker for lower limb prosthetic socket fit quantification and prosthetic health. study design: experimental study design. methodology: in this research article, sus scrofa domesticus (pork) muscle and gallus gallus domesticus (chicken) muscle specimens (10mm width x 45mm height x 4mm depth) were submerged into saline baths while an instron testing machine applied displacement controlled tensile loads. time stamped, load, displacement and acoustic signal (hydrophone) data was collected. findings: the pork muscle was tested to failure being subject to tensile load. prior to failure, no peaks were found in the amplitude or frequency of the acoustic signal to indicate that either tissue deformation or failure was occurring. data gathered during chicken muscle testing was inconclusive. conclusions: results displayed that tensile testing of pork intercostal muscle produced tissue deformation and failure with no detectable change in the amplitude or frequency of the background sound during tensile loading. the other specimens failed before reaching the same levels of tensile load. further studies are required in order to address the numerous limitations of this study. 1 article info received: may 08, 2018 accepted: august 24, 2018 published: august 28, 2018 citation buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no 5, 2018. keywords prosthetics, acoustic emission, deep tissue injury, pressure ulcer, tissue shear, prosthetic socket design, diabetic foot, soft tissue, lower limb prosthetic, tensile load. open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 abbreviations ae : acoustic emission dti : deep tissue injury dpu: deep pressure ulcers https://doi.org/10.33137/cpoj.v1i1.30354 https://orcid.org/0000-0003-3947-293x mailto:arjan.buis@strath.ac.uk https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 introduction in the uk, 72% of lower limb amputations result from dysvascularity and/or neuropathy, with the majority of amputations occurring at trans-tibial level (1). the two commonly used trans-tibial socket designs are based on conflicting principles, both of which have a lack of substantiation regarding the internal conditions of the residual limb within the socket (2). the first design, the ptb socket, applies specific loads to pressure-tolerant areas, whereas the hydrocast socket aims to dispense pressure uniformly through the “stiffest path principle” (3). it is advocated that hydrocast sockets have a greater ability to generate “ideal” pressure distribution together with a reduction in internal shear (2).there is, at present, no consensus on what defines an “optimal” socket design or fit (3, 4). there is a growing belief among researchers that the ‘coupling’ stiffness between the hard prosthetic socket and the weight bearing structure, the skeleton, is a major factor in optimising the quality of a socket design (3, 5), as it can reduce the amount of tissue deformation during load bearing and consequently reduce the shear stresses in the soft tissues (3-5). due to the aetiology of these amputations, the residual limb is at increased risk of developing a deep tissue injury (dti) due to peripheral neuropathy, impaired blood supply and/or poor skin condition (6). if a dti is misdiagnosed or diagnosed late in this population, there can be a risk of revision amputation being necessary due to increasing tissue necrosis. this severely impacts the patient’s quality of life and places excess strain on the healthcare system (7). this highlights the avid prerequisite for comprehensive assessment of prosthetic socket fit and function. to date, research focusing on residuum-socket interface pressures has been unable to establish a direct relationship between interface pressures and the magnitude of deep tissue stresses. these studies have inadequately quantified the mechanical stresses within deep internal tissues (8, 9). as a result, interfacial pressures alone are unlikely to change socket design principles and additional performance/bio markers are therefore needed. deep tissue injury (dti) ulceration as a direct result of pressure can be characterised into six differing classifications according to the national pressure ulcer advisory panel. however, they are broadly divided into two groups: superficial or deep (10). superficial ulcers can be triggered by a variety of mechanisms, including a combination of moisture and heat, in conjunction with frictional and shear forces, infection, poor nutrition and/or peripheral neuropathy (8, 10-12). these ulcers are confined to the epidermis, can be identified by visual inspection of the skin (10) and have been confirmed reversible (8, 13). on the contrary, deep pressure ulcers (dpus) are secondary to dtis and have a different mechanism of origin (8). the term dti designates an ulcer that experiences high pressure at the bone-muscle interface, below intact skin (11, 13). a dti can have the visual appearance of a deep bruise and can often be mistaken for a superficial pressure ulcer, resulting in appropriate diagnosis often occurring at a late stage (6, 8, 10). as deep skeletal muscle undergoes necrosis secondary to pressure, it begins to stiffen which transfers the stresses to more superficial layers of tissue (8, 9, 12). as a result, necrotic tissue will develop in these superficial layers continuing the positive-feedback cycle of muscle stiffening and tissue necrosis until the ulcer appears on the epidermal layer (8, 12). exemplar situations in which dtis can often occur include immobile patients in bed, wheelchair bound patients or users of orthoses/prostheses the primary focus of this study (14, 15). dti’s have historically been alleged to be instigated by factors which can include pressure-related ischaemia and/or ischaemia-reperfusion injuries due to the quick flow of blood rushing back to ischaemic tissues upon withdrawal of the applied load (6, 8, 11, 13, 16, 17). however, more contemporary studies suggest that tissue deformation and ischaemia related deformation injuries can also contribute to a dti (13) . interestingly, it has been shown that tissue deformation results in permanent muscle damage following two hours of compressive loading whereas muscle damage due to ischaemia can be reversible (14, 17). this information highlights the necessity of imminent investigation regarding the compression of soft tissues and the applied deformation forces on soft tissues, in order to reduce the risk of a dti. portnoy et al assessed the specific forces acting on a transtibial residuum and analysed the internal 2 https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 mechanical condition of the soft tissues during static weight bearing. they established that in a transtibial residuum, soft tissues are subject to tensile, compressive and both internal and external shear forces during static and dynamic loading. it was concluded that the magnitude of tensile and shear strain within the tissues was much greater than the compressive strain (2) . differing academics seconded this when they demonstrated that dtis tend to develop in areas where highest shear strain values have been recorded during tissue loading (14) and that tissue damage increases with increasing shear strain (13). thus, it has been concluded that the force in a transtibial socket most likely to cause a dti is shear force. shear forces can be separated into internal and external categories. shear can develop when external frictional forces stretch the top layer of the skin as it slides against a supporting surface (e.g. against a bone or against a prosthetic socket) (18, 19). this theory can then be applied to internal shear forces where subcutaneous tissue and muscle glide over one another. internal and external shear forces interact. for example, the presence of internal shear increases around the ischial tuberosities where the skin has been stretched. this type of shear is commonly seen in pressure ulcer formation, especially around the sacrum, however, this can occur on any part of the body. both external frictional forces and internal tissue shear contribute to the six certified classifications of pressure ulcers, however, these two forces are more significant in dtis than in superficial ulcers (18). contemporary publications exploring socket fit have utilised sensors in order to research socket-interface pressures in transtibial users (20) . however, it is now recognised that the condition of the deep muscle tissue is not accounted for in these studies and that the close proximity of the deep vascular structures to bony prominences is likely to result in much higher pressures than present on the surface of the residuum (8). therefore, the sole use of interface sensors at the skin’s surface is inadequate in detecting high pressures at the bone-muscle interface. consequently, this method does not highlight dti risk and thus, does not truly quantify conclusive results with regard to an ‘optimal socket fit’. detection of dti’s could therefore be used as an aid to assess the biomechanical fit of a prosthetic socket, along with other methods, using tissue deformation as a parameter of measurement. measurement of dti in clinical practice at present, there are several current clinical techniques which have a body of supporting research substantiating their usage in the detection of dtis. however, these current methods prove to be invasive (serum chemistry), provide latent information i.e. not real time (urine and serum chemistry along with mri), expensive (mri) or require specialist knowledge to interpret (sonography and mri). currently, sonography seems most promising in dti detection due to portability and economic factors, however, further research is required to define the specific characteristics. another possible method of detecting the presence of a dti, which holds pre-empted potential, may be to analyse acoustic emission (ae) that may arise from shear stress. when an external load is applied to a material, deformation occurs as a result of the relative movement between atomic chains, with this movement emitting acoustic waves (21, 22). the phenomenon is known as ae and currently has well established applications in structural and civil engineering. ae detection is classified as a non-destructive and a non-invasive realtime method to assess the integrity of the internal structure of a material (21-23). it does not require an input signal as the acoustic waves are generated by the material and transducers can be placed anywhere on the materials surface to monitor acoustic output (22). however, the detection of ae may be affected by background noise and there is potential for the signal to be distorted as it propagates through a material. therefore, mechanically advanced microphones may be obligatory in order to accurately capture the signals (21, 23). sound waves are released as muscle contracts/is loaded and these waves may then be detected using acoustic myography (amg), a specialised ae technique (2428). it is believed that the noise arises from the lateral oscillations of fibres (24, 28, 29). interestingly, the contractile force is proportional to the volume of the acoustic noise (24, 25). this signal has been utilised, by adapting amg, to analyse muscle activity and fatigue (24, 26, 28, 29) and to control an externally powered upper limb prosthesis (27). the movement which occurs 3 https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 within muscle tissue during deformation could potentially release ae waves as atomic dislocations produce pressure waves that travel through the tissue and are detectable on the surface (23, 24) . tendons and skeletal muscles that are composed of uni-directional fibres have the potential to develop shear stresses when these tissues are loaded multi-directionally (30), which can be identified by ae. research hypothesis and objectives the objectives of this study are to firstly select a microphone suitable for this experimental work to enable simultaneous recording of acoustic frequencies and deformation data from tissue specimens under tensile loading, to visually examine data for acoustic peaks at critical points in the deformation data collected and then to present the results with future recommendations. this study hypothesizes that acoustic signals are emitted from skeletal muscle tissue when it is deformed during loading. methods specimens and equipment two baseline tests were carried out using a sample of fabric webbing. this style of webbing was selected as it is manufactured from a weaved structure composing of uni-directional fibers with low elasticity – crudely comparable with soft tissue. the tensile testing was performed with an instron testing machine (electropuls™ e10000) and allowed to exercise a displacement control test. this means that the tissue under investigation is stretched with a selected loading rate samples were loaded under tension (1mm/s to 20mm) and simultaneous length increase is recorded. biological test specimens firstly included intercostal muscle and bone from sus scrofa domesticus (pork). additionally, domensticus (chicken) was selected, ensuring the muscle belly of the gastronomicus and its attachment to bone was intact. bone was utilised in order to maintain tissue structure throughout testing (figure1). these biological test specimens were selected due to the organized uni-directional nature of the fibers and the ease of availability. the specimens were dissected when the muscle was frozen, however, due, to the initial freezing process, the muscles were contorted and had to be thawed and refrozen into a more easily dissectible state. the specimens were thawed at room temperature prior to testing. samples were prepared by isolating the muscle and cutting the bone at the attachment points into a size suitable for the clamps to receive (figure 2), with an approximate width of 1cm per unit. bone was used as a clamping point to minimise slippage during testing. figure1. pork specimen clamped in bath via rib bones. enlarged view of specimen illustrating preparation and size of sample. figure 2. view looking downwards into bath with chicken specimen clamped in place (test 1). as part of specimen was clamped out with the bath, a rod was used to conduct the “tapping” signal to synchronise data collection. an instron testing machine (electropuls™ e10000) with a 1kn load cell was used to apply a tensile force to each specimen. specimens were clamped onto serrated grips and submerged in a physiological saline solution (composition: 0.9g sodium chloride – purified water qs 100ml) bath (30mm x 30mm x 30mm) to simulate an in vitro environment (figure 3). as sound 4 https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 propagates through liquid at a faster rate than through air, the test environment was anticipated to aid acoustic detection, providing an improved medium for the hydrophone. unfortunately, the temperature of the saline could not be controlled in this study due to the customisation of the test equipment. an omni-directional hydrophone with an inbuilt preamplifier was placed within the bath to detect acoustic signals. the selected hydrophone had a frequency range of 0.1hz – 180khz (bruel and kjaer type 8103) and a voltage sensitivity of 25.4µv/pa. the sensitivity range of the hydrophone is within the acoustic range between 20hz and 20khz as illustrated in figure 4 and capable to operate in the target range. the hydrophone was consistently positioned 10mm from the tissue under analysis. a digital oscilloscope (gratten ga1000cal) recorded hydrophone data in real-time and had a sampling rate of 40mhz. the instron and hydrophone data were recorded simultaneously with the load cell “tapped” at the beginning of each test to act as a data synchronisation point. test protocols wavematrix™ software gathered time, load and displacement data at a sampling rate of 1000hz. the amplitude of the acoustic signal was recorded on the oscilloscope with a sampling rate of 40mhz. microsoft excel™ was used to generate graphical representations of the wavematrix™ data. the oscilloscope captured amplitude information which was imported to matlab allowing for signal processing in the frequency and time domain by applying the fourier transform to the full data set: 𝑋(𝑘) =∑𝑥(𝑗)𝜔𝑁 −(𝑗−1)(𝑘−1) 𝑁 𝑗=1 where, 𝜔𝑁 = 𝑒(−2𝜋𝑖)/𝑁 there is a lack of current available evidence to support the optimal tensile displacement rate and threshold during testing, as studies commonly select 1, 5 and 10mm/s for tissue compression rates with no apparent justification (31, 32). in this study, displacement rate and threshold was restricted by the collection of realtime acoustic data from the oscilloscope display. figure 3. instron test machine setup including saline bath and hydrophone. figure 4. sound frequency spectrum. two baseline tests with fabric webbing were conducted at a ramp rate of 1mm/s to a total displacement of 20mm by a tensile load. one sus scrofa domesticus sample and three gallus gallus domesticus samples were loaded under tension at 1mm/s to 20mm/s. wavematrix™ software was instructed to collect data for 2 seconds prior to the commencement of displacement to allow the “tapping” of the load cell to be recorded. results tests with three different tissues have been conducted but not all have been successful. the narrative will describe the tests that were disregarded and the main body of the result section will describe the tests used for analysis. 5 https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 narrative a baseline test with a fabric with uni-directional fiber orientation, followed by experiments using animal specimen, sus scrofa domesticus (pork) and gallus gallus domensticus (chicken) respectively. during the first tests utilising the fabric specimen, the specimen slipped in the clamp which disturbed the recording and were disregarded. during tensile testing of the pork intercostal muscle specimen, the tissue failed by detaching from the bone. the chicken specimen utilised for test 2 slipped in the clamp during testing, being subject to a maximum load of 18n and was omitted from the data set. baseline in test 2, the fabric failed after approximately 7s at a tensile load of 112n and at a displacement of 8mm (figure 5). figure5. plot of load and displacement against time of baseline test 2 using fabric webbing. initial data spike from “tapping” of load cell for data synchronisation point clearly captured. figure 6. load/displacement against time of pork intercostal muscle under tensile load resulting in specimen failure at 34 n. sus scrofa domesticus testing the inter-costal muscle failed after 3 seconds at a load of 34n and a displacement of 3mm (figure 6). gallus gallus domensticus testing in test 1 with chicken muscle, the muscle bulk was entirely submerged in the bath, however, one end of the bone lay out with the bath due to the specimen size (figure 2). as part of the specimen lay out with the bath, a rod was used to conduct the “tapping” signal in order to synchronise data collection. this specimen successfully completed testing without fail and experienced a maximum load of 13n. the specimen utilised for test 2 comprised of a larger muscle belly which also lay out with the dimensions of the bath. in test 3, the specimen failed after 18.3s at a displacement of 16mm (figure 7) as the tendon became detached from bone. the peak load applied to the specimen was 20n, occurring at 12s. figure 7. load /displacement against time during test 3 on chicken tissue in which specimen failed. acoustic emission data in both the fabric and the chicken specimens, the acoustic data collected during testing did not include enough data points. this resulted in inadequate findings on these samples. thus, acoustic data could only be analysed on the sole pork specimen. the amplitude recording (figure 8 and 9) detected the sound created by the “tapping” signal, with only the trace of background noise before and during the tensile testing phase. figure 10 shows a plot of amplitude and frequency (figure 10). 6 https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 discussion this study investigated the hypothesis that animal soft tissue emits acoustic noise when subject to deformation from an externally applied load. due to the limited number of trials performed in this study, statistical analysis could not be performed. figure 8. amplitude against time (s) of tensile test on pork specimen. data spike from “tapping” of load cell clearly displayed. figure 9. zoomed in display of amplitude against time (s) for tensile test on pork specimen. this illustrates the absence of any sound which may be associated with deformation of the specimen. figure 10. plot of amplitude against frequency for pork specimen showing no discernible change in frequency of the recorded signal. during testing of the pork intercostal muscle specimen, failure occurred as the soft tissue detached from the bone, thus indicating tissue deformation was likely taking place at the bony attachment and not within the muscle bulk. as a result, further testing on these specimens was not conducted. in the limited data collected for these samples, no event occurred in the acoustic data to indicate tissue was being deformed or failed. the only event clearly captured in either the amplitude or frequency reading was the “tapping” of the load cell which was required in order to synchronise the data. the above results also highlight that during experimentation of the chicken tissue, inconclusive results were collected and thus no correlation could be explored. however, as the maximum load measured during testing of pork (35n) was higher than that recorded on any of the tests on chicken (20n), it may be postulated that no correlation would be seen between the acoustic output and tissue deformation in these tests either. the fabric webbing failed at a load of 112n. 112n may have been a high enough load to produce an ae data recording reading, however, unfortunately there was no recoding in this study. these results are therefore unable to indicate a correlation between tissue deformation and emission of an acoustic signal. though the instron testing machine applied a tensile loading force in this feasibility study, this is not the same as shear, which, as previously mentioned, has an important role in dti development (13, 14, 18). however, it may be assumed that internal shear stresses were present during tensile loading, as the pressure gradient induced by the tensile loading may give rise to internal shear stresses (3, 5, 24). there were several limitations to this feasibility study. a degree of slippage was noted between each specimen and the clamps during loading. consequently, the specimens may not fully subjected to the applied load. the interaction between skeletal muscle and other biological tissues was not taken into account in this study, as the aim was to investigate whether or not acoustic signals are emitted from isolated skeletal muscle undergoing deformation. future work would be required to investigate this phenomenon in a cadaveric limb segment. 7 7 https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 it may not be appropriate to extrapolate in vitro results to the in vivo environment due to the large number of assumptions encountered and the complexity of muscle structure. most biological tissues (including skeletal muscle and connective tissue) are described as viscoelastic in nature (3, 5, 33). this means they exhibit both viscous (i.e. fluid-like behavior resisting shear) and elastic (i.e. rapidly returning to original state) characteristics when strained. specifically, with muscle it displays elasticity when it returns to its original shape when stretched then released (34). a muscle’s viscosity is the internal resistance to motion (35). as a result of this, viscoelasticity time is also an important factor as viscosity dissipates the shear force (32, 36). this is further corroborated by porcine muscle displaying different levels of stress to a variety of strain rates (34). considering the loading of a trans-tibial residual limb during ambulation with a prosthesis, the residuum will be subject to tensile, compressive and shear forces simultaneously and in a cyclic manner. the residual limb is loaded for 62% of the gait cycle (37) but it will also be subject to external forces during swing phase due to the inertia of the swinging limb. the vertical displacement of the tibia due to socket pistoning during the gait cycle has been investigated in many studies (3840) with the mean value of the collective movement in the proximodistal direction throughout a full gait cycle being 57mm while using a patellar-tendon bearing socket (40). the relative movement between the tibia and the surrounding soft tissue will lead to tissue deformation. however, tibial movement not only occurs in the coronal plane but also in the sagittal plane, so deforming forces are being applied to various locations on the residuum and in different directions. thus, in amputees, dti is more likely to occur over long periods of cyclical gait motion in a multi-directional orientation. if it were possible to record acoustic data over a longer period of time, a slower more realistic strain rate could be employed along with compression testing to recreate forces experienced by the residual limb. the values chosen for this study were not based on quantitative evidence (due to a significant lack of literature investigating the loading rates of internal soft tissue in a residual limb during gait) but on values selected in preceding studies in which tissue damage was examined through displacement (31, 32). furthermore, the results presented in this feasibility study are not statistically significant as a very limited number of tests were conducted. it has also been noted that this study did not investigate a range of tissue loading rates and thus future work would preferably investigate these as well as cyclic loading conditions. moreover, the sample numbers collected from the acoustic data in this study did not allow for sufficient examination of the correlation between tissue deformation and acoustic output. another point of note is that, ideally, biological specimens should be prepared and tested within a few hours of death to preserve the mechanical properties. it has been documented that freezing muscle alters and reduces its strength (41). in contrast, huang et al has documented that thawing then refreezing tendon in less than three cycles does not significantly alter the mechanical properties (42). despite these conflicting findings, biological tissue should be tested fresh if possible or it should be preserved in a manner that reflects the in vivo environment with minimum freezing. an alternative transducer may be a contact microphone which is placed on the surface of the material being tested. the inclusion of a pre-amplifier may also enhance the detection of any sound signal being emitted. further investigation is required to carry out a robust correlation analysis between tissue deformation and acoustic emission. this would ideally incorporate a variety of transducers to detect sound output, testing of various tissues and the application of a range of tissue displacement rates. the acoustic emission of tissue under shear is most likely be over shadowed by muscle noise and sliding tissues during human movement (mechanomyogram (mmg)). in addition, the noise generated by the prosthetic intervention itself and contact with clothing will in all probability render a clinical application useless. conclusions this feasibility study provides a foundation of results regarding tissue deformation and ae. results displayed that tensile testing of pork intercostal muscle produced tissue deformation and failure with no detectable change in the amplitude or frequency of the background sound 8 https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 during tensile loading. there is a more than strong argument that acoustic shear emission during soft tissue deformation is over shadowed by muscle activation noise (mmg) and noise generated in the prosthetic system during gait. the other specimens failed before reaching the same levels of tensile load, and, as testing of other tissue did not reach the same levels of tensile load, it is unlikely that any acoustic events could have been detected from these specimens either. further studies are required in order to address the numerous limitations of this study. declaration of conflicting interests no conflict of interest declared. this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. competing interests none declared sources of support university of strathclyde – experimental work took place on campus. ethical approval not required author contribution arjan buis: conceptualization, formal analysis, investigation, methodology, visualization, writing original, review & editing. francesco guarato: conceptualization, formal analysis, investigation, methodology, visualization. jason law: formal analysis, investigation, methodology, visualization, writing original. zoe ralston: formal analysis, investigation, methodology, visualization, writing original. anna courtney: methodology, visualization, writing original. review & editing. references 1. national amputee statistical database (nasdab). the amputee statistical database for the united kingdom. edinburgh: information services division, nhsscotland, 2006/07. 2. portnoy s, yizhar z, shabshin n, itzchak y, kristal a, dotan-marom y, et al. internal mechanical conditions in the soft tissues of a residual limb of a trans-tibial amputee. journal of biomechanics. 2008;41(9):1897-1909. doi: 10.1016/j.jbiomech.2008.03.035. 3. klasson b, buis, awp. prosthetic socket fit; implications of basic engineering principles. 94 912 advanced prosthetic science (manual 3): ncpo, university of strathclyde, glasgow; 2006. 4. mak af, zhang m, boone da. state-of-the-art research in lower-limb prosthetic biomechanics-socket interface: a review. journal of rehabilitation research and development. 2001;38(2):161-174. 5. klasson b, buis a. appreciation of prosthetic socket fitting from basic engineering principles. national centre for training and education in prosthetics and orthotics, university of strathclyde, 1995. 6. portnoy s, siev-ner i, shabshin n, kristal a, yizhar z, gefen a. patient-specific analyses of deep tissue loads post transtibial amputation in residual limbs of multiple prosthetic users. journal of biomechanics. 2009;42(16):2686-2693. doi: 10.1016/j.jbiomech.2009. 08.019. 7. saluwa a, middleton c, gilbertson a, kodavali k, neumann v. stump ulcers and continued prosthetic limb use. prosthetic and orthotics international. 2006;30(3): 279–285. doi.org/10.1080/03093640600836139. 8. gefen a, levine j. the false premise in measuring bodysupport interface pressures for preventing serious pressure ulcers. journal of medical engineering & technology. 2007; 31(5), 375-380. doi.org/10.1080/03091900601165256. 9. yarnitzky g, yizhar z, gefen a. real-time subjectspecific monitoring of internal deformations and stresses in the soft tissues of the foot: a new approach in gait analysis. journal of biomechanics. 2006;39(14):2673-2689. doi: 10.1016/j.jbiomech.2005.08.021. 10. npuap, epuap. treatment of pressure ulcers: quick reference guide. washington dc: national pressure ulcer advisory panel; 2009. 11. mak aft, yu y, kwan lpc, sun l, tam ewc. deformation and reperfusion damages and their accumulation in subcutaneous tissues during loading and unloading: a theoretical modeling of deep tissue injuries. journal of theoretical biology. 2011;289(0):65. doi: 10.1016/j.jtbi.2011.08.022. 12. gefen a, gefen n, linder-ganz e, margulies ss. in vivo muscle stiffening under bone compression promotes deep pressure sores. journal of biomechanical engineering. 2005; 127(3), 512-524. doi: 10.1115/1.1894386. 9 https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 13. ceelen kk, stekelenburg a, loerakker s, strijkers gj, bader dl, nicolay k, et al. compression-induced damage and internal tissue strains are related. journal of biomechanics. 2008;41(16):3399-3404. doi: 10.1016/j.jbiomech.2008.09.016 14. stekelenburg a, strijkers g, parusel h, bader dl, nicolay k, oomens cw. role of ischemia and deformation in the onset of compression-induced deep tissue injury: mribased studies in a rat model. journal of applied physiology. 2007;102(5):2002-2011. doi.org/10.1152/japplphysiol.01115.2006. 15. bansal c, scott r, stewart d, cockerell cj. decubitus ulcers: a review of the literature. international journal of dermatology. 2005;44(10):805-810. doi: 10.1111/j.13654632.2005.02636.x. 16. gefen a, van nierop b, bader dl, oomens cw. straintime cell-death threshold for skeletal muscle in a tissueengineered model system for deep tissue injury. journal of biomechanics. 2008;41(9):2003-2012. doi: 10.1016/j.jbiomech.2008.03.039. 17. stekelenburg a, gawlitta d, bader dl, oomens cw. deep tissue injury: how deep is our understanding? archives of physical medicine and rehabilitation. 2008;89(7):1410-1413. doi.org/10.1016/j.apmr.2008.01.012 18. gefen a, farid k, shaywitz i. a review of deep tissue injury development, detection and prevention: shear savvy. ostomy wound management. 2013;59(2):26-35. 19. gefen a. risk factors for a pressure-related deep tissue injury: a theoretical model. medical & biological engineering & computing. 2007;45(6):563-573. doi: 10.1007/s11517-007-0187-9. 20. courtney a, orendurff ms, buis a. effect of alignment perturbations in a trans-tibial prosthesis user: a pilot study. journal of rehabilitation medicine. 2016; 22;48(4):396-401. doi.org/10.2340/16501977-2075. 21. williams rv. acoustic emission. adam hilger, bristol. 1980:116. 22. kohn dh. acoustic emission and non-destructive evaluation of biomaterials and tissues. critical reviews in biomedical engineering. 1995;23(3-4):221-306. doi: 10.1615/critrevbiomedeng.v23.i3-4.20. 23. thomas im. acoustic emission as a technique for monitoring failure within vertebral bodies. glasgow: university of strathclyde; 1986. 24. stokes m, dalton pa. acoustic myography for investigating human skeletal-muscle fatigue. journal of applied physiology, 1991;71(4):1422-1426. doi: 10.1152/jappl.1991.71.4.1422. 25. islam a, sundaraj k, ahmad b, ahamed n, ali a. mechanomyography sensors for muscle assessment: a brief review. journal of physical therapy science.2012; 13591365. doi.org/10.1589/jpts.24.1359. 26. barry dt, geiringer sr, ball rd. acoustic myography: a noninvasive monitor of motor unit fatigue. muscle & nerve. 1985;8(3):189-194. doi:10.1002/mus.880080303. 27. barry dt, leonard ja, gitter aj, ball rd. acoustic myography as a control signal for an externally powered prosthesis. archives of physical medicine and rehabilitation. 1986;67(4):267-269. 28. barry d, cole n. muscle sounds are emitted at the resonant frequencies of skeletalmuscle. ieee. transactions on biomedical engineering. 1990;37(5):525-531. doi: 10.1109/10.55644. 29. frangioni jv, kwan-gett ts, dobrunz le, mcmahon ta. the mechanism of lowfrequency sound production in muscle. biophysical journal. 1987;51(5):775-783. doi: 10.1016/s0006-3495(87)83404-5. 30. buis a, mcgarry a, gachagan a, riches p. acoustic emission, detection and analysis of deep tissue injury (dti) in trans-tibial prosthetic sockets (research proposal). university of strathclyde: aopa; 2011. 31. tonuk e, silver-thorn mb. nonlinear elastic material property estimation of lower extremity residual limb tissues. ieee transactions on neural systems and rehabilitation engineering. 2003;11(1):43-53. doi: 10.1109/tnsre.2003.810436. 32. silver-thorn mb. in vivo indentation of lower extremity limb soft tissues. ieee transactions on rehabilitation engineering. 1999;7(3):268-277. doi: 10.1109/86.788464. 33. lieber rl, leonard me, brown-maupin cg. effects of muscle contraction on the loadstrain properties of frog aponeurosis and tendon. cells tissues organs. 2000;166(1):48-54. doi:10.1159/000016708. 34. nie x, cheng j, chen w, weerasooriya t. dynamic tensile response of porcine muscle. journal of applied mechanics-transactions of the asme. 2011;78(2)-78. doi:10.1115/1.4002580. 35. nihat oz. fundamentals of biomechanics : equilibrium, motion, and deformation. margareta n, editor. new york: new york: springer; 1999. 36. christensen rm. theory of viscoelasticity: an introduction. new york: new york: academix press; 1971. 37. sanders je, daly ch, burgess em. clinical measurement of normal and shear stresses on a trans-tibial stump: characteristics of wave-form shapes during walking. 11 10 https://doi.org/10.33137/cpoj.v1i1.30354 buis a, guarato f, law j, ralston z, courtney a. a feasibility study to investigate if there is a correlation between soft tissue deformation and acoustic emission. canadian prosthetics & orthotics journal, volume 1, issue 1, no5, 2018.doi: https://doi.org/10.33137/cpoj.v1i1.30354 open access soft tissue deformation and acoustic emission volume 1, issue 1, article no. 5, august 2018 prosthetics and orthotics international. 1993;17(1):38-48. doi.org/10.3109/03093649309164353. 38. grevsten s, erikson u. a roentgenological study of the stump-socket contact and skeletal displacement in the ptbsuction prosthesis. upsala journal of medical sciences, 1975;80(1):49-57. doi.org/10.3109/03009737509178991 39. narita h, yokogushi k, shii s, kakizawa m, nosaka t. suspension effect and dynamic evaluation of the total surface bearing (tsb) trans-tibial prosthesis: a comparison with the patellar tendon bearing (ptb) trans-tibial prosthesis. prosthetics and orthotics international. 1997;21(3):175-178. doi:10.3109/03093649709164551. 40. lilja m, johansson t, oberg t. movement of the tibial end in a ptb prosthesis socket: a sagittal x-ray study of the ptb prosthesis. prosthetics and orthotics international. 1993;17(1):21-26. doi:10.3109/03093649309164351. 41. gottsauner-wolf f, grabowski jj, chao ey, an kn. effects of freeze/thaw conditioning on the tensile properties and failure mode of bone-musclebone units: a biomechanical and histological study in dogs. journal of orthopaedic research : official publication of the orthopaedic research society. 1995;13(1):90-95. doi: 10.1002/jor.1100130114. 42. huang h, zhang j, sun k, zhang x, tian s. effects of repetitive multiple freeze-thaw cycles on the biomechanical properties of human flexor digitorum superficialis and flexor pollicis longus tendons. clinical biomechanics (bristol, avon), 2011;26(4):419-23. doi: 10.1016/j.clinbiomech.2010.12.006. 11 https://doi.org/10.33137/cpoj.v1i1.30354 balkman g, morgan s, gaunaurd i, kristal a, amtmann d, gailey r, hafner b.j. performance testing in people with lower limb amputation: interviews with prosthetists, physical therapists, and physicians. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32018 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) performance testing in people with lower limb amputation: interviews with prosthetists, physical therapists, and physicians geoffrey balkman1*, sara morgan1, ignacio gaunaurd2, anat kristal2, dagmar amtmann1, robert gailey2, brian j. hafner1 1 department of rehabilitation medicine, university of washington, seattle, wa, usa. 2 department of physical therapy, university of miami, miami, fl, usa. * email: gbalkman@uw.edu doi: https://doi.org/10.33137/cpoj.v1i2.32018 introduction a variety of performance-based tests are available to assess mobility in people with lower limb amputation (lla)1. selection of a specific test is likely to be guided by the clinical value of tasks patients perform; the space and equipment available to administrator the test; and/or the time required to set up, administer, score, and interpret the test results. the aim of this study was to collect information about the clinical value of performance tests, and the space, equipment, and time available to rehabilitation specialists who provide care to people with lla (i.e., prosthetists, physical therapists (pts), and physical medicine and rehabilitation (pm&r) physicians). methods cross-sectional semi-structured telephone interviews were conducted to gather information about the type of performance tasks administered to people with lla, the clinical environment in which tests may be administered, and the resources available (e.g. time, space, and equipment). a convenience sample of prosthetists, pts, and pm&r physicians was recruited through investigators’ professional contacts. interviews were conducted by phone, recorded, and transcribed. an interview guide2 was used to ask participants about tasks with clinical value; space, equipment, time available for administration; and general barriers or facilitators to performance testing. qualitative data were reviewed for themes and quantitative data were tabulated to compare results across and within professional groups.3 results prosthetists, pts, and pm&r physicians (n=8, 9, and 8, respectively) from 12 us states participated in the interviews. walking (in parallel bars and the hallway) and moving from sit-to-stand were tasks used by all participants to assess people with lla. other tasks included standing (n=20/25), stair climbing (n=16/25), transfers (n=14/25), navigating obstacles (n=13/25), variable cadence walking (n=12/25), and single limb stance (n=11/25). most participants stated that they had access to more than one room for patient evaluation and all participants had a corridor at least 25 feet long. the majority (n=8/9) of pts had access to a therapy gym, whereas fewer physicians (n=5/8) and prosthetists (n=2/8) had access to larger indoor spaces. all participants reported that they had the equipment (e.g., stopwatch and tape measure) necessary to conduct timed or distance tests. most (n=16/25) had a meter or yardstick that could be used to conduct select tests. only about half (n=12/25) of the clinicians interviewed had a treadmill. most physicians (n=5/8) reported they wished to spend 10 minutes or less on performance assessment, whereas the majority of prosthetists (n=5/8) and pts (n=7/9) were willing to spend 21 minutes or more (figure 1). figure 1. maximum time clinicians reported to be willing to spend on performance testing during one appointment conclusion participants interviewed in this study identified a variety of factors that can promote or inhibit performance testing of people with lla in clinical practice. differences in space, equipment, and time resources available to different rehabilitation specialists may inform which tests can be conducted in which settings, or suggest the need for referrals when additional time, space, or equipment is necessary. results of this study may also mailto:*%20email:%20gbalkman@uw.edu https://doi.org/10.33137/cpoj.v1i2.32018 balkman g, morgan s, gaunaurd i, kristal a, amtmann d, gailey r, hafner b.j. performance testing in people with lower limb amputation: interviews with prosthetists, physical therapists, and physicians. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32018 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) inform development of new performance tests. similarities in basic equipment and frequently used tasks imply that performance tests intended for use across disciplines and settings should include tasks with clinical value (i.e., sit to stand and walking) that require only basic equipment (i.e., tape measure and stopwatch). significance knowledge of tasks with value and resources available to rehabilitation specialists can help improve selection, administration, and development of performance tests. references 1. condie, e, et al. lower limb prosthetic outcome measures: a review of the literature 1995 to 2005. 2006; j prosthet orthot, 18, p13-45. doi: 10.1097/00008526-20060100100004 2. kallio h, et al. systematic methodological review: developing a framework for a qualitative semi-structured interview guide. j adv nurs. 2016; 72: 2954-65. doi:10.1111/jan.13031 3. turner iii dw. qualitative interview design: a practical guide for novice investigators. qual rep. 2010; 15: 754-60. disclosure this research was supported by a grant from the national institutes of health (award number r01hd065340). https://doi.org/10.1111/jan.13031 burke j, fiedler g. online access to research papers – changes over time. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018, abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32010 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) online access to research papers – changes over time julie burke, goeran fiedler* department of rehabilitation science and technology, university of pittsburgh, pennsylvania, usa. * email: gfiedler@pitt.edu introduction the successful implementation of evidence based practice (ebp) depends significantly on practitioners’ access to relevant research articles. it has been argued that the time consuming nature of ebp is a major detriment to its acceptance and widespread use,1 and the logistical difficulties, like having to retrieve research publications of interest from the local university library, are likely to exacerbate this issue. in recognizing the associated adverse effects that this problem could present for knowledge generation and dissemination, the idea to make all research findings publicly available online led to the conception of the world wide web in the early 1990s.2 however, many scientific journals that are slow to abandon their subscription-based business models hide their online content behind paywalls, charging article fees that are usually in the range between $20 and $40. acknowledging the barriers to ebp that these fees can impose, we have previously compared different strategies for prosthetists and orthotists to maximize their free online access to relevant research literature. the respective data collection in the spring of 2017 resulted in the finding that approximately 40% of search results in google scholar linked to freely available full papers, whereas the remaining 60% links offered only the abstract, but not the full paper, free-of-charge.3 in light of the ever progressing efforts to improve public availability of research, such as the open-access publishing movement or the respective requirements mandated by research funding agencies, we hypothesized that the ratio of freely available online articles is increasing over time, and we repeated our data collection one year after the initial study. methods a total of three literature searches on the website scholar.google.com were conducted, once in the spring of 2017 and once more in the spring of 2018. the search terms, exclusion of patents and citations, and the publication time frame (from 2007 to 3/27/2017) were kept consistent between the two data collections. the first 20 results for each search were analyzed to determine whether they contained a link that would allow full-paper access without charge. the number of such links were then compared across assessment times. results figure 1 shows the differences between assessment times. overall, 75% of the top search results in 2018 contained links to freely accessible full papers. figure 1: number of freely accessible research papers for three searches at scholar.google.com. discussion our hypothesis was supported by the finding that open access to articles on google scholar almost doubled within one year. there are different possible explanations for this, including a change in composition of the top 20 of the search rankings. as higher-impact articles are ranked higher in the search result listings, it is possible that articles that were cited relatively often over the past year have moved up and displaced other articles. this mechanism appears likely if it is assumed that articles that are freely accessible are read (and potentially cited) by more people than less easily accessible articles. another factor at play may be an increased volume of full-paper articles that are being shared by their authors in online repositories, something that is often allowed with some restrictions by the publishing journal. the copyright rules on some materials may have been 0 5 10 15 20 pin and lock, suction, suspension, prosthesis, elderly microprocessor, knee, athletes diabetes, prosthetic, liner, ulcer 2017 2018 doi: https://doi.org/10.33137/cpoj.v1i2.32010 https://doi.org/10.33137/cpoj.v1i2.32010 mailto:gfiedler@pitt.edu https://doi.org/10.33137/cpoj.v1i2.32010 burke j, fiedler g. online access to research papers – changes over time. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018, abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32010 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) changed as well. only three literature searches and only 20 search results for each search were analyzed for this study. this may limit the generalizability of findings somewhat. however, it is likely that respective searches for ebp purposes are inevitably limited in scope, and that our protocol is therefore representative of realistic situations. conclusion the percentage of freely-accessible research papers that can be found among the top search results on google scholar has substantially increased over the past year. this may be due to a combination of more highly ranked papers becoming freely available and more freely available papers becoming highly ranked. clinical applications practitioners in the field of prosthetics and orthotics often depend on freely accessible research papers to conduct ebp. the here described trend is beneficial in this context. references 1. andrysek j, christensen j and dupuis a. prosthetics and orthotics international. 2011; 35: 30-8. http://journals.sagepub.com/doi/full/10.1177/0309364610389 353 2. leiner bm, cerf vg, clark dd, et al. acm sigcomm computer communication review. 2009; 39: 22-31. http://www.isoc.org/oti/printversions/0797prleiner.html 3. burke j and fiedler g. 44th annual aaop meeting and scientific symposium. new orleans, la 2018. https://doi.org/10.33137/cpoj.v1i2.32010 http://www.isoc.org/oti/printversions/0797prleiner.html medema a, henness d, steinhorst k, moauro r, reuland m, whelan r, kester s, bateni h. effect of level of amputation on postural steadiness among lower extremity amputees. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32015 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) effect of level of amputation on postural steadiness among lower extremity amputees arianna medema, douglas henness, kendra steinhorst, robert moauro, michael reuland, robert whelan, shawna kester, hamid bateni* physical therapy program, northern illinois university, dekalb, il, usa. * email: hbateni@niu.edu doi: https://doi.org/10.33137/cpoj.v1i2.32015 introduction increased rate of fall, reduced balance confidence and increased fear of falling is reported for lower extremity amputees.1 fall rate also increases at higher levels of amputation1. this study aims to compare postural steadiness of different levels of lower extremity amputees through comparison of time and frequency domain variables of postural sway. methods data from six lower extremity amputees (2 unilateral trans-tibial [utt], 1 bilateral trans-tibial [btt], 2 unilateral transfemoral [utf] and 1 unilateral hip disarticulation [uhd]) with the average age of 51±16 years was analyzed. participants were instructed to stand (bare feet heels together, 5-7 degrees toe-out) on a force platform and were tested for three standing conditions: a eyes open, beyes closed and cstanding on airex 2.5” thick balance pad (www.airex.com). each test was repeated three times (block randomized). force platform data were collected for 35 seconds (fs=100). anteroposterior and mediolateral time series data were filtered through a fourth-order zero phase butterworth low-pass filter with cut-off frequency of 5 hz. the first 8 sec. and last 2 sec. of data were cut off to remove any potential lead-in/out effect. results mean ml distance cop sway was significantly affected by both level of amputation (f3,5=15.08 p<.0001) and standing condition (f2,5=7.45 p=.0017). maximum velocity of ml and amputation level were also significantly related (f3,5=8.71 p<.0001). root mean square distance from central sway point in medio-lateral direction, which is known to be single best predictor of future falling risk was affected by both level of amputation and standing conditions (p=0.0008). total power computed as the integrated area of power spectrum also was significantly affected by both amputation and standing conditions (p<.0001). resultant centroidal frequency was affected by level of amputation (p=.017). figure 1: comparison of ml distance of postural sway for different levels of amputation. btt/utt=bilateral/unilateral trans-tibial, utf= unilateral trans-femoral, uhd= unilateral hip disarticulation. conditions 1=eyes open, 2=eyes close, 3= standing on the foam. note significant differences between unilateral and bilateral amputees. conclusion changes in time and frequency domain variables are significantly related to the level of amputation. variation in frequency domain variable may be indicating application of different strategies in postural steadiness and control of sway. significance impact of level of amputation of frequency domain variables of postural sway may lead to new assessment of prosthetic limb. references 1miller wc et al., the prevalence of risk factors of falling and fear of falling among lower extremity amputees. arch. phys. med. rehabil. 2001;82: 1031-1037. doi:10.1053/apmr.2001.24295 disclosure no conflict of interest exists for this study. mailto:hbateni@niu.edu https://doi.org/10.33137/cpoj.v1i2.32015 https://doi.org/10.1053/apmr.2001.24295 mankoff j, savage s, eckert s, ngo c, fiedler g. user experiences with traditional and 3d-printed upper extremity prostheses, development of a comprehensive survey instrument. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32009 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) user experiences with traditional and 3d-printed upper extremity prostheses, development of a comprehensive survey instrument jennifer mankoff 1, saiph savage 2, sydney eckert*3, chelsea ngo*4, goeran fiedler5 1 allen school of computer science & engineering, university of washington, seattle, wa, usa. 2 human computer interaction lab, computer science and electrical engineering department, west virginia university, morgantown, wv, usa. 3department of clinical psychology, seattle pacific university, wa, usa. 4western university of health sciences, pediatric therapy network, pomona, usa. 5department of rehabilitation science and technology, university of pittsburgh, pittsburgh, pa, usa. *3 email: eckerts@spu.edu *4 email: csngo@westernu.edu introduction additive manufacturing (am), colloquial known as 3dprinting, has been deemed capable to revolutionize a great number of industries, including the health care industry.1 in the field of upper limb prosthetics, it has been attempted to leverage the potential advantages of am, such as crowd based design optimization, infrastructure independent fabrication, and economical material use, in the interest of providing low-cost, readily available devices to recipients whose needs were only insufficiently met by traditional approaches of device prescription and fitting. while the popular media has been quick to emphasize the potential – perceived or real – of 3d printed prostheses, clinicians have generally been less euphoric and the base of scientific evidence on questions related to these applications has been small.2 as with most research endeavors in prosthetics and orthotics, recruiting sufficient sample sizes to allow solid conclusions is a perennial challenge also in this sub-field. as a consequence, the effectiveness of the many 3dprinted upper limb devices made by volunteers of the enable community (fig.1) is yet to be determined. selfreported outcome assessment tools can somewhat mitigate the issue of low sample sizes. however, none have been applied to a wider range of device classes, to allow comparative analyses across those. we describe the development and preliminary testing of an online based survey tool to generate comparison outcome data for a wide variety of upper limb prosthetics devices, including varieties that are 3d-printed by hobbyists. methods a focus group consisting of experts from different disciplines related to upper extremity prosthesis device production was assembled to develop a comprehensive outcome survey tool, following four stages: 1. definition of goals and target populations that will be addressed with the survey. 2. identification of existing survey tools that can be adapted for the purposes of the eventual instrument. 3. combination of core areas identified under 1.) and 2.) into a comprehensive questionnaire, utilizing skip logic and other methods to minimize survey length and user burden. 4. iterative testing and refining of the draft survey to assure technical function as well as appropriateness of evaluation and reporting approaches. the group, members of which are located throughout the continental us, conducted bi-weekly online meetings over the course of several months to accomplish these objectives. the eventual survey was realized in qualtrics research core (seattle, wa) and is now available online. data collection is currently ongoing. results the current survey has 107 and 108 questions respectively in the version for caregivers (capturing experiences of underage users) and for end users. those questions are organized in 10 blocks (table 1), some of which are only presented if previous answers suggest that they are applicable in the individual case. completion time for the complete survey is estimated at 15-20 minutes. doi: https://doi.org/10.33137/cpoj.v1i2.32009 https://doi.org/10.33137/cpoj.v1i2.32009 mailto:*3%20email:%20eckerts@spu.edu mailto:*4%20email:%20csngo@westernu.edu https://doi.org/10.33137/cpoj.v1i2.32009 mankoff j, savage s, eckert s, ngo c, fiedler g. user experiences with traditional and 3d-printed upper extremity prostheses, development of a comprehensive survey instrument. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32009 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) discussion dependable outcome data is important to evaluate and compare novel approaches to prosthetic device provision. survey tools can reach a large target population and have a comparably low burden of participation, which mitigates the common issue of recruiting a desirably large sample population. however, establishing the internal and external validity of such tools can be challenging. other challenges include assuring the sensitivity and specificity of an instrument that is intended to address the same construct in a wide and diverse population or range of device classes, respectively. we have attempted to solve those challenges by developing the survey based on existing tools and leveraging the combined insights from a diverse expert panel. it is our hope that it will succeed to gather a substantial quantity of outcome data with the here presented comprehensive survey tool. this will help objectively assess the comparative effectiveness of different prosthesis concepts, including 3d-printed devices, in specific user scenarios. conclusion a recently developed comprehensive outcome data survey for users of upper limb prosthetic devices addresses limitations of existing tools. clinical applications the survey may be used for individual outcome assessment purposes over time. aggregated data may inform prescription of conventional and novel prosthetic devices in the future. references 1.giannatsis and dedoussis. additive fabrication technologies applied to medicine and health care: a review. int j adv manuf tech 40.1-2 (2009): 116-127. doi: 10.1007/s00170-0071308-1 2. jelle ten kate, smit, 3d-printed upper limb prostheses: a review. breedveld, disabil rehabil assist technol. 12.3 (2017): 300-314. doi:10.1080/17483107.2016.1253117 3. zuniga, jorge, et al. cyborg beast: a low-cost 3d-printed prosthetic hand for children with upper-limb differences. bmc res notes (2015): 8:10. doi: 10.1186/s13104015-0971-9 table 1: overview of survey contents block description num. of questions 1 eligibility 6 2 demographics 12 3 type of device 20 4-7 usefulness of specific device(s) 14 each 8 problems with device 9 9 e-nable community 3 10 conclusion 2 figure 1: volunteer assembling a 3dprinted prosthetic device table 1: overview of survey contents block description num. of questions 1 eligibility 6 2 demographics 12 3 type of device 20 4-7 usefulness of specific device(s) 14 each 8 problems with device 9 9 e-nable community 3 10 conclusion 2 figure 1: volunteer assembling a 3dprinted prosthetic device figure 1: volunteer assembling a 3d-printed prosthetics device. https://doi.org/10.33137/cpoj.v1i2.32009 ana gallego a, mccarthy j, mcgrath m, kercher a, zahedi s, moser d. patient trial evaluation of a perforated, pin-lock prosthetic liner for sweat management. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32011 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) patient trial evaluation of a perforated, pin-lock prosthetic liner for sweat management ana gallego*1, joe mccarthy1, michael mcgrath1, alan kercher2, saeed zahedi1, david moser1 1endolite technology centre, basingstoke, uk 2endolite north america, miamisburg, oh, usa * email: ana.gallego@blatchford.co.uk doi: https://doi.org/10.33137/cpoj.v1i2.32011 introduction among amputees, the most commonly reported problem affecting daily quality-of-life is excessive sweating1,2. some studies report that as many as seven out of ten amputees are affected1,3. compared to able-bodied people, trans-tibial amputees expend up to 40% more energy during every-day activities, which contributes to excess perspiration4. particularly common is localised sweating on the residual limb. this could be due to the use prosthetic liners made from non-porous, cushioning materials, such as tpe gel, polyurethane or silicones. with these problems in mind, a type of silicone liner has been produced that contains perforations along the length and at the distal end. these perforations permit the warm air to move away from the residuum, allowing better air circulation and, if sweating does occur, the perforations allow moisture to escape. the result is drier, cooler skin and a healthier environment for the residual limb. this study reports prosthetist and patient feedback data from trials of the pin-lock version of these liners. methods a custom-made questionnaire was constructed to gather feedback about both liner design and patient outcomes during the trial. all patients transitioned from their previous prosthetic liners to perforated, pin-lock liners (silcare breathe locking liner – sbl – endolite). of all the patients identified as suitable for the trial, 23 transtibial amputees supplied responses (3 x k2, 14 x k3, 6 x k4; 20 x unilateral, 3 x bilateral; 17 male, 6 female). questionnaires were requesting at fitting, and 1, 3 and 6 months into the trial. results the prosthetist feedback proved largely positive for the sbl liner. at the fitting stage, 100% of patients had a problem with sweating (n=18), while after 3-4 months of wearing the sbl, only 33% did (n=12), some of which stated that this was only during exercise. after 6 months, the only patients that still had a problem with sweating specified that it was ‘greatly reduced’. at each stage of the trial, the distal seal held sufficient vacuum for over 77-92% of respondents, while no patient reported finding this seal uncomfortable at any stage in the trial. from the patient’s perspective, the self-perceived issues with sweating reduced from 89% ‘yes’ at fitting (n=19), to exclusively ‘only during exercise’ or ‘greatly reduced’ after 3 and 6 months. when asked whether they ever had to stop using their prosthesis due to sweating, 47% stated “yes” at fitting (n=17), whereas after 3-4 months, no-one had this issue. i likert scale was used to rate how much heat/sweat there was compared to their previous liners (1=much less, 4= same, 7=much more); mean responses were less than 3 at all stages of the trial. figure 1: the prosthetist feedback from different time points during the patient trial conclusion the findings of the sbl patient trials showed the benefits of the liner perforations. the impact of excess sweating on the patients’ everyday activities was largely reduced. in particular, sweating to the extent that it stopped prosthetic limb use was completely eradicated. this will have a large impact on their independence and consequently their quality-of-life. mailto:ana.gallego@blatchford.co.uk https://doi.org/10.33137/cpoj.v1i2.32011 ana gallego a, mccarthy j, mcgrath m, kercher a, zahedi s, moser d. patient trial evaluation of a perforated, pin-lock prosthetic liner for sweat management. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32011 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) significance appropriate sweat management can vastly improve the quality-of-life and residual limb health of amputees. references 1.hagberg & brånemark. consequences of non-vascular transfemoral amputation: a survey of quality of life, prosthetic use and problems. prosthet orthot int. 2001;25(3):186–194. doi:10.1080/03093640108726601 2.meulenbelt et al. determinants of skin problems of the stump in lower-limb amputees. arch phys med rehabil. 2009 jan;90(1):74–81. doi:10.1016/j.apmr.2008.07.015 3.berke et al. comparison of satisfaction with current prosthetic care in veterans and servicemembers from vietnam and oif/oef conflicts with major traumatic limb loss. j rehabil res dev. 2010;47(4):361. doi:10.1682/jrrd.2009.12.0193 4.gonzalez & mathews. femoral fractures in patients with lower extremity amputations. arch phys med rehabil. 1980;61(6):276–280. disclosure the authors are employees of endolite north america or blatchford (the parent company of endolite north america); the manufacturer of the liner being evaluated in this study. https://doi.org/10.1080/03093640108726601 https://doi.org/10.1016/j.apmr.2008.07.015 mcdonald c.l, cheever s.m , morgan s.j., hafner b.j. prosthetic limb user experiences with crossover feet: a focus group study to explore outcomes that matter. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 2629, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32042 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) prosthetic limb user experiences with crossover feet: a focus group study to explore outcomes that matter cody l. mcdonald*, sarah m. cheever, sara j. morgan, brian j. hafner department of rehabilitation medicine, university of washington, seattle, wa, usa. * email: codym@uw.edu doi: https://doi.org/10.33137/cpoj.v1i2.32042 introduction a variety of prosthetic feet are available to meet the diverse needs of people with lower limb amputation. outcome measures selected to assess comparative effectiveness of prosthetic feet are most often chosen by clinicians and researchers.1 therefore, these measures may not reflect the outcomes that are most important to lower limb prosthesis users. qualitative research can give voice to prosthesis users and promote the consideration of user priorities when selecting outcome measures for clinical assessment and research studies. this study explored the lived experience and outcomes of importance to individuals who have worn both traditional energy storing feet and crossover feet. methods sample: convenience sample of prosthesis users eligibility criteria: at least 18 years of age, lower limb amputation, at least 1 year prosthesis use, and prior use of an energy storing foot and crossover foot. procedures: an in-person two-hour focus group was held. all procedures were approved by a uw irb. analysis: a phenomenological theoretical framework was applied to data analysis. two investigators coded the focus group transcript independently, and a third mediated any discrepancies. open coding was used to identify initial ideas. axial coding and inductive reasoning were used to identify themes. transcripts were reviewed to identify final themes and representative text. investigators developed a framework of themes and identified instruments capable of measuring outcomes that mattered to focus group participants. results five people with lower limb amputation (4 males/1female), aged 41-59 years (mean 45.6±7.7 years), and who used a prosthesis daily (mean 15.2±1.1 hours) participated in the focus group. three categories of themes arose from this focus group: direct outcomes, external influences, and indirect outcomes (table 1). themes such as balance & stability well matched standardized measures. themes like naturalness and peer influence did not align with available measures, suggesting that new outcome measures may need to be developed. other themes like endurance and sustained gait quality included elements (e.g., time of day, fatigue and gait symmetry) that may be challenging to capture with current assessment methods. figure 1. framework of study themes mailto:codym@uw.edu https://doi.org/10.33137/cpoj.v1i2.32042 mcdonald c.l, cheever s.m , morgan s.j., hafner b.j. prosthetic limb user experiences with crossover feet: a focus group study to explore outcomes that matter. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 2629, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32042 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) conclusion prosthesis user engagement through qualitative research can inform selection of outcomes that matter to users. measurement of outcomes that matter may maximize clinicians’ and researchers’ ability to assess the effects of prosthetic interventions on users’ lives. references 1.hafner bj. energy storage and return prostheses: does patient perception correlate with biomechanical analysis? clin biomech. 2002; 17(5), 325-44. doi: https://doi.org/10.1016/s0268-0033(02)00020-7 disclosure this work was funded by a walter c. and anita c. stolov award and an orthotics and prosthetics outcomes research award (no. w81xwh-15-1-0458). https://doi.org/10.1016/s0268-0033(02)00020-7 wengerd l. functional utility of wearing a myoelectric orthosis for upper extremity paralysis due to spinal cord injury. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32021 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) functional utility of wearing a myoelectric orthosis for upper extremity paralysis due to spinal cord injury lauren wengerd, the ohio state university, columbus, oh 43210, usa. email: lauren.wengerd@osumc.edu doi: https://doi.org/10.33137/cpoj.v1i2.32021 introduction spinal cord injury (sci) remains a leading cause of longterm disability in the united states with the majority of injuries resulting in incomplete quadriplegia due to cervical lesions.1 this leads to significant neurological impairment including upper extremity (ue) weakness and decreased independence with self-care activities of daily living (adls). previous work demonstrated that using a myoelectric elbow-wrist-hand orthosis as a therapeutic adjunct to a multi-week rehabilitation regimen resulted in decreased ue motor impairment and increased function in stroke survivors with moderate ue hemiparesis.2 the purpose of this case study was to determine if wearing a myoelectric elbow-wrist-hand orthosis reduces upper extremity motor impairment and increases functional ability in an individual with chronic, incomplete spinal cord injury and resultant quadriplegia. methods the current findings come from a case study involving a 49year-old male with chronic (>4 years post-injury), traumatic sci at the c4-c5 level. as a result of his injury, he presented with severe, bilateral upper extremity paresis and was completely dependent for all adls prior to this study. he was provided with a custom-fit myopro 2.0 motion-g upper extremity orthosis to facilitate return to independence with basic self-care activities such as feeding and grooming. after receiving the orthosis, he completed three sessions with an occupational therapist and was then instructed on a home exercise program (hep) to continue making progress toward his goals. approximately one month after receiving his orthosis, he was re-assessed by his occupational therapist on a variety of self-care activities as well as physical abilities such as ue active range of motion, strength, and spasticity. results the subject demonstrated significant improvements in selffeeding tasks while wearing the myopro 2.0 motion-g orthosis, progressing from requiring total assistance to requiring setup to don the orthosis. he also demonstrated significant improvements in active range of motion (before: 0 degrees active elbow flexion against gravity; with orthosis: 100 degrees active-assisted elbow flexion against gravity) and decreased muscle spasms when wearing the myoelectric orthosis. all of these results were recorded after 32 days with three occupational therapy sessions and 15 self-directed sessions (approximately every other day) wearing the orthosis at home. figure 1. myopro 2.0 motion-g upper extremity orthosis.1 conclusion this case study is the first published research demonstrating the functional and clinical utility of a myoelectric upper extremity orthosis to improve elbow and hand function. these findings indicate that this may be a promising orthosis for increased function and quality of life for individuals with chronic sci and resultant quadriplegia. significance prior to this work, the majority of published research using myoelectric orthoses for upper extremity impairment has been in stroke and brachial plexus injury. this is one of the first documented cases of the functional utility of a myoelectric orthosis for individuals with traumatic spinal cord injury with resultant quadriplegia. this case study shows promising evidence that a mailto:lauren.wengerd@osumc.edu https://doi.org/10.33137/cpoj.v1i2.32021 wengerd l. functional utility of wearing a myoelectric orthosis for upper extremity paralysis due to spinal cord injury. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32021 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) myoelectric upper extremity orthosis may increase function and quality of life for individuals with sci. references 1.sekhon, l. h., fehlings, m. g. epidemiology, demographics, and pathophysiology of acute spinal cord injury. spine. 2001; 26(24s), s2-s12. 2.peters, h. t., page, s. j., persch, a. giving them a hand: wearing a myoelectric elbow-wristhand orthosis reduces upper extremity impairment in chronic stroke. archives of physical medicine and rehabilitation. 2017; 98(9), 1821-1827. doi: 10.1016/j.apmr.2016.12.016 disclosure the author of this work is a clinical consultant for myomo, inc. in addition to her primary role as a phd student at the ohio state university. acknowledgment this work was funded by myomo, inc. https://doi.org/10.1016/j.apmr.2016.12.016 delgado c, latour d. use of externally-powered orthosis to address complexities associated with bilateral brachial plexopathy. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32047 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) use of externally-powered orthosis to address complexities associated with bilateral brachial plexopathy cassandra delgado, debra latour, handspring clinical services, middletown, ny, usa. email: cassandra@poaprosthetics.com doi: https://doi.org/10.33137/cpoj.v1i2.32047 introduction brachial plexus injuries are often caused by trauma, tumors or inflammation. the severity of the injury may vary, however in most traumatic cases, the supraclavicular region is impacted. depending on the severity of the injury, surgery is often indicated early due to the likelihood of nerve regeneration. surgical procedures include neurolysis, nerve grafting and neurotisation; where approximately 45% will regain adequate function to perform activities of daily living (adls) and return to work. according to current data, approximately 9,700 individuals per year will remain disabled due to the injury. for individuals where surgical intervention has not provided improvement in function, alternative solutions must be investigated. particularly for those with bilateral involvement, potential solutions include orthotic technology. like users of prosthetic technology, there is a wide array of technology available, intended to meet the diverse needs experienced by the population of individual who have lost function of the upper limbs. this paper describes the challenges experienced by an individual with bilateral brachial plexus injuries and addresses the case solutions using collaborative interprofessional practice.1-4 methods the subject of this reflective case study is a 45-year-old female who presents with bilateral brachial plexus injuries due to complications from a bilateral mastectomy. she experienced complete loss of function of both upper extremities when she awoke from the surgery. she was discharged from the hospital without return of bilateral upper limb function. after 2 years of pt and ot, she regained ~80% function in her nondominate left arm, however she fatigues quickly. she has some wrist and elbow flexion/extension range of motion return in her right upper extremity, however her strength is minimal and fatigue is apparent. the subject was employed as a family physician and has not been able to return to work, as she cannot carry her tablet or other equipment, is not able to type to chart on patients, cannot hold a scalpel to perform office procedures, and is not able to raise her arms to perform assessments. evaluation. it appeared that the subject would be a candidate for an externally-powered device. measures: a full evaluation was completed by both an ot and orthotist. the quick dash was administered with an initial general disability index of 88.6. in addition, the subject completed the mcgann client feedback form. the subject received initial training in the device that included application to functional skills, in particular, tasks that involve reaching, lifting, pushing and bringing the hand to the head, such as to self-feed or to groom hair. results subsequent testing reveals continued functional improvement, orthosis satisfaction and decreased perceptions of disability. these factors appear to align with the client-centered goals to return to work in any capacity as a physician, continue to provide for her two daughters. figure 1: externally-powered technology for individual with bilateral brachial plexus injury. discussion the externally-powered elbow-wrist-hand orthosis can provide significant benefit to the individual with bilateral involvement. the client with brachial plexus injury can mailto:cassandra@poaprosthetics.com https://doi.org/10.33137/cpoj.v1i2.32047 delgado c, latour d. use of externally-powered orthosis to address complexities associated with bilateral brachial plexopathy. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32047 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) perform functional tasks and engage in meaningful activities that other interventions cannot fully address. references 1. michael, j.w, nunley j.a. special considerations: brachial plexus injuries: surgical advances and orthotic/prosthetic management. atlas of limb prosthetics: surgical, prosthetic, and rehabilitation principles; 12a, 2016. (http://www.oandplibrary.org/alp/chap12-01.asp). 2. page s.j, hill v, white s. portable upper extremity robotics is as efficacious as upper extremity rehabilitative therapy: a randomized controlled pilot trial. clinical rehab: 6,494-503, 2012. https://doi.org/10.1177/0269215512464795. 3. sakellariou, et al. treatment options for brachial plexus injuries. isrn orthopedics; 3,3, 2014. http://dx.doi.org/10.1155/2014/314137. 4. mendal s, david b. a myoelectrically controlled wristhand orthosis for brachial plexus injury: a case study. j of prost ortho, 4,171-175, 1992. disclosure none. http://www.oandplibrary.org/alp/chap12-01.asp https://doi.org/10.1177/0269215512464795 http://dx.doi.org/10.1155/2014/314137 burke j, fiedler g. clinicians’ access to peer-reviewed prosthetics research articles. canadian prosthetics & orthotics journal, volume 1, issue 1, no 3, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30009 research article issn: 2561-987x all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x volume 1, issue 1 2 0 1 8 https://doi.org/10.33137/cpoj.v1i1.30009 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com burke j, fiedler g. clinicians’ access to peer-reviewed prosthetics research articles. canadian prosthetics & orthotics journal, volume 1, issue 1, no 3, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30009 1 open access clinicians’ access to peer-reviewed prosthetics research articles volume 1, issue 1, article no. 3, august 2018 research article clinicians’ access to peer-reviewed prosthetics research articles burke j, fiedler g* department of rehabilitation science and technology, university of pittsburgh, pennsylvania, usa. *corresponding author dr goeran fiedler, phd, assistant professor, department of rehabilitation science and technology, university of pittsburgh, suite 403, bakery square, 6425 penn ave, pittsburgh, pa 15206, usa. orcid number: https://orcid.org/0000-0003-1532-1248 email: gfiedler@pitt.edu tel: +1-412-624-6475 doi: https://doi.org/10.33137/cpoj.v1i1.30009 abstract background: evidence-based practice (ebp) is an important cornerstone of responsible clinical decision-making, and by extension, of high quality care provision in prosthetics and orthotics. however, many clinicians have been reluctant to embrace ebp, citing barriers such as high costs and time demands that are associated with obtaining pertinent published evidence for individual care scenarios. objectives: the purpose of this study was to determine how accessible peerreviewed research articles are to prosthetists who seek to implement ebp techniques into their clinical work without expending unreasonable amounts of time and money. methodology: two approaches were utilized. an academic approach entailed a search through five peer-reviewed research journals, including the journal of prosthetics and orthotics and prosthetics and orthotics international. a practical approach simulated a typical evidence search as it might occur in the field, using a number of different clinical questions to inform search terms in google scholar. the ratio of freely accessible articles was computed and compared for both approaches. findings: out of a total of 796 prosthetics-relevant articles published in the analysed journals over the last years, 600 (75.4%) were found to be accessible to the public without any cost incurred. the practical approach showed that, among the top twenty search results for each search query, on average 40% to 75% of articles were freely available. conclusions: a majority of pertinent research papers is already publicly available to anybody with internet access. prosthetists would not be required to invest in journal subscriptions or have to spend time at an academic library to obtain these articles. however, it is a concern that evidence-based decision making may be flawed if not all literature on a topic is considered. there is still a substantial fraction of articles that are not freely available to practitioners, motivating a continued expansion of open-access policies in the field. article info received: july 20, 2018 accepted: august 2, 2018 published: august 10, 2018 citation burke j, fiedler g. clinicians’ access to peer-reviewed prosthetics research articles. canadian prosthetics & orthotics journal, volume 1, issue 1, no 3, 2018. doi: https://doi.org/10.33137/cpoj. v1i1.30009 keywords prosthetics, evidence based practice, accessibility, bibliometric study, review, peer-reviewed, research article, open access journal, prosthetists. https://orcid.org/0000-0003-1532-1248 mailto:gfiedler@pitt.edu https://doi.org/10.33137/cpoj.v1i1.30009 https://doi.org/10.33137/cpoj.v1i1.30009 https://doi.org/10.33137/cpoj.v1i1.30009 burke j, fiedler g. clinicians’ access to peer-reviewed prosthetics research articles. canadian prosthetics & orthotics journal, volume 1, issue 1, no 3, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30009 2 open access clinicians’ access to peer-reviewed prosthetics research articles volume 1, issue 1, article no. 3, august 2018 introduction accessibility of peer-reviewed research articles has been cited as a barrier that prosthetists and orthotists must overcome in order to use evidencebased practice (ebp) in their clinical practices.1-4 short of frequenting a local university library that may or may not hold the publications of interest and/or allow some access by the general public, there are four basic ways by which practitioners may acquire peer-reviewed research articles: openaccess or free-access articles (these are free to the public, usually online), paying for online versions of individual articles in peer-reviewed journals, subscribing to peer-reviewed journals that contain articles of interest, or joining an organization that includes journal access as one of the membership benefits. one example of an open access journal relevant to the field of prosthetics and orthotics (p&o) was the journal of rehabilitation research and development (jrrd), which focused on veterancentric rehabilitation research, including articles related to prosthetics, orthotics and other assistive technologies.5 jrrd was funded by the us department of veterans affairs to cover operation costs, but ceased publishing within the rehabilitation research and development service in march of 2017, referring authors to public library of science (plos) instead.6 the recently introduced canadian prosthetics & orthotics journal (cpoj) is utilizing a more commonly found open-access model based on article-processing charges. select open-access articles can also be found in the field’s specialized journals that utilize the classic membership/subscription model for revenue, including the journal of prosthetics and orthotics (jpo) and prosthetics and orthotics international (poi). jpo offers open-access to articles that are two years or older, and poi offers open-access to all articles three years and older as well as select recent articles through sage publishing. several heavily cited papers focusing on prosthetic research have also been published in journals that are not specialized in p&o.7 these journals include gait and posture (gp) or the archives of physical medicine and rehabilitation (apmr). in studies that focused on potential barriers p&o practitioners face when incorporating ebp into their own clinical practices, lacking accessibility has often been defined as any kind of cost incurred when attempting to access the articles desired. this cost includes membership requirements, individual article fees, and/or subscription fees that may be encountered when a clinician attempts to research a clinical question. however, it has not yet been quantified how prohibitive these costs actually are, and whether the growing open-access movement in the past decades has helped mitigate the problems associated with costs of ebp. the purpose of this study was therefore to determine how much of the published evidence in a sub-field of prosthetics research is freely accessible to practitioners. this information is useful in discussing the actual effect that costbarriers have on prosthetists’ ability to perform ebp in their clinical practice. we assumed that having access to half of the published body of knowledge would enable to perform ebp in most cases, especially when there is a general consensus within the literature. based on this deliberation, we hypothesized that the amount of currently available open-access articles in the field of limb prosthetics exceeds this 50% threshold. we further hypothesized that the share of relevant openaccess articles increases over time. method while our protocol entailed the search and review of a large number of literature sources, it was not with the intent to evaluate or summarize the scientific contents of those papers. rather, all eligible publications were tallied by whether they were freely accessible online or not.8 this study utilized two separate approaches to investigate the hypothesis. an academic approach had the aim to determine how many of the relevant (prosthetics) articles in a given selection of journals were open-access articles. the second was a practical approach aimed to simulate what a prosthetist may utilize in daily practice by searching for evidence on a specific clinical topic in a scholarly literature database. in order to also estimate the tendency of changes over time, this practical burke j, fiedler g. clinicians’ access to peer-reviewed prosthetics research articles. canadian prosthetics & orthotics journal, volume 1, issue 1, no 3, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30009 3 open access clinicians’ access to peer-reviewed prosthetics research articles volume 1, issue 1, article no. 3, august 2018 approach was repeated after a one-year interval. the previously determined criterion of an accessibility percentage of 50% was used for interpretation of the findings across approaches. academic approach of all the journals with p&o content, five of the most commonly read were used as sample for this study: jpo, poi, jrrd, apmr and gp. the number of prosthetics articles available in each journal was determined using the search terms “prosthetic,” “prosthetics,” “prosthetist,” “prosthesis,” and “prostheses” as keywords in scopus, one of the largest abstract and citation databases. the five journal names were entered under the filter category “source title”. the search was conducted in late march of 2017 and was narrowed to publication years from 2007 to 2016 (i.e., only articles and reviews published between january 1, 2007 and december 31, 2016 were included in the initial selection). search results were scrutinized to determine whether a limb prosthesis was part of the study design, and only articles were included that either focused on the design or fabrication of a prosthetic device or that otherwise utilized the device in a significant manner in the research. for example, if a prosthesis was merely mentioned but was not substantial for the study protocol at all, the respective paper was excluded from analysis. articles that focused on prosthetic implants (other than osseointegrated limb prostheses) or on neuroprostheses were also excluded from this study, as it is unlikely that papers on those topics have great relevance in the realm of ebp in limb prosthetics at this time. for the same reason, articles that focused exclusively on the surgical implantation of osseointegrated prosthesis and not any of the follow up care were also excluded. for the first round of filtering, article abstracts and titles were scanned for relevance to the study. during the second round of review any articles that were questionable for relevance were reviewed in full to make sure they met the inclusion requirements. the remaining articles were then looked up on each journal’s publishing website to determine which articles were accessible to the public as of march 27, 2017. the ratio of freely accessible articles to the total number of articles found was then computed separately for each journal. practical approach in order to simulate the typical process a prosthetist goes through when gathering evidence to address a clinical problem, three random clinical questions were formulated and appropriate search terms (table 1) were entered in google scholar, a search engine that searches scholarly literature and academic resources.9 formulation of the question was intended to reflect both recommended approaches (e.g., using a pico – population, intervention, comparison, outcome – format) and less structured questions that may be posed to clinicians by their patients. search terms were derived from the main terms contained within each question. to keep congruency between the two approaches, filters were used to limit the search results to only articles from peer-reviewed journals that were published between january 1, 2007 and march 27, 2017. table 1: research questions and search terms used in google scholar. the accessibility of the first 20 search results for each question was determined by clicking on the original hyperlinks that are provided by the google scholar website. in the event that no such link was listed or that the listed link did not lead to a full-text version of the article in question, the article was recorded as “not accessible”. while there may have been other avenues to tracking down such articles online through a variety of different websites (e.g., an article of which only the abstract is available on the website sciencedirect may be – unbeknownst to google scholar – posted in full on the private website of the article author), it is arguably least complicated to just click on the links provided by google scholar. a busy clinician with limited time for ebp will in many cases prefer this expedited approach to evidence gathering. research question search terms is a pin-and-lock suspension or a suction suspension better for prosthesis suspension in elderly patients? pin and lock, suction, suspension, prosthesis, elderly are microprocessor knees recommended for athletes? microprocessor, knee, athletes what prosthetic liner is best for diabetic patients with a history of ulcers? diabetes, prosthetic, liner, ulcer https://doi.org/10.33137/cpoj.v1i1.30009 burke j, fiedler g. clinicians’ access to peer-reviewed prosthetics research articles. canadian prosthetics & orthotics journal, volume 1, issue 1, no 3, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30009 4 open access clinicians’ access to peer-reviewed prosthetics research articles volume 1, issue 1, article no. 3, august 2018 results academic approach the initial search in scopus turned up 1,042 articles. after title, abstract, and full-text screening, 796 total articles were included in this analysis. with nearly 300 articles, poi had the most prosthetics related articles, followed by jrrd, jpo, gp and apmr respectively. the amount of total free articles per journal followed a similar trend, with poi containing the largest number of accessible articles, closely followed by jrrd and jpo, then apmr and lastly gp. the ratio of accessible papers was greatest in jrrd, followed by apmr, jpo, poi and gp. overall, about three out of every four articles in these journals were freely accessible by the public (table 2). table 2: number of reviewed journal articles (from 2007 through 2016). journal total articles number of free articles ratio of free articles poi 297 196 66% jrrd 183 183 100% jpo 169 151 89% apmr 72 67 93% gp 75 3 4% totals 796 600 75% practical approach the total number of freely accessible articles found through the three searches in 2017 was 24 out of a total of 60 obtained articles, with an average of eight accessible articles per search, with a standard deviation of one. out of the articles collected, 16 (27%) were published in one of the five journals used in the academic approach. repeating the same searches (using the same filters) one year later showed that the number of freely accessible articles among the top search results had increased to 45 out of 60 (figure 1). discussion having free access to just a small part of relevant published research is a significant barrier to incorporating ebp into clinical practice. based on our initial assumption that having access to at least 50% of papers would reasonably enable prosthetists to conduct ebp effectively and efficiently, our findings suggest that a sufficient ratio of research articles in prosthetics are indeed freely available to practitioners. both our approaches agreed very well with each other that approximately three out of every four articles relevant to the field were accessible by an individual at no cost. figure 1: changes in the number of freely accessible articles among the top 20 search results for google scholar searches between march 2017 and march 2018.10 open access articles, especially in the specialized journals poi and jpo, can arguably be a valuable resource for prosthetists to utilize, given that these journals contain more clinically relevant research than other journals, like apmr or gp, that publish prosthetics research among research in many other areas. approximately 57% of the accessible articles identified in our academic approach, were gathered from poi and jpo. judged by this, the conditions for ebp in the fields of prosthetics and orthotics appear to be favourable compared to other health sciences. while open accessibility of peer-reviewed articles through google scholar (the practical approach) was eventually found to be at around 75% as well, the same ratio was much lower when first investigated a year prior. in early 2017, only two out of every five peer-reviewed articles on average were accessible to an individual at no cost. that open access to articles on google scholar almost doubled within one year has different possible explanations, including a change in composition of the top 20 of the search rankings. https://doi.org/10.33137/cpoj.v1i1.30009 burke j, fiedler g. clinicians’ access to peer-reviewed prosthetics research articles. canadian prosthetics & orthotics journal, volume 1, issue 1, no 3, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30009 5 open access clinicians’ access to peer-reviewed prosthetics research articles volume 1, issue 1, article no. 3, august 2018 higher-impact articles (i.e., articles that are cited more often) are ranked higher in the search result listings, and it is conceivable that articles that were referenced frequently over the past year have moved up and displaced less popular articles. this would be supported by the circumstance that articles that are freely accessible are by trend read (and potentially cited) by more people than comparable less easily accessible articles. the volume of full-paper articles that are being shared by their authors in online repositories, where they are freely accessible by the public, may have increased over time as well. this would have been encouraged if the copyright rules that impose restrictions on that practice have been loosened by some publishing journals. irrespective of that, many dated materials become more freely available over time by trend (as detailed above), which may have played a role in the year-on-year differences as well. improvements in google scholar over the period between analyses appear to have led to a better selection of links to full-text papers. it was noted during the first data collection in 2017 that some of the google scholar links pointed to articles, already known to be open-access that could, however, not be accessed through the link provided by google scholar without a login or associated fee to the article. for example, a preview of a jrrd article, which is open-access, was found through a proquest link that was given as a result in the google scholar websearch.11 proquest is a search engine used to access journals, databases and ebook resources, that requires a login for access. as membership requirements were included in what was considered inaccessible, this known open-access article was marked as inaccessible based on the study methods. it is possible that our results were affected by some limitations of this study. only three clinical questions were formulated to inform the search term selection, resulting in a small and specific sample of data. a larger selection of search terms may bring about different results, especially if a topic is concerned that has only recently been widely investigated (i.e., has most relevant papers still subject to access restrictions) or has conversely not yielded much new research in many years (i.e., most papers fallen out of copyright protection). the top twenty articles that were included in our analysis were not filtered for relevance to the searched questions. this was done to increase replicability of the study, but may have led to some of the resulting papers not being responsive to the original question. in the same sense, it may have been possible to identify more articles by including more than five search terms in the academic approach. likewise, the exact phrasing of the clinical questions in the practical approach, which depends on the practitioner’s professional judgment and on the peculiarities of the individual case, may influence the selection of search terms and thereby the eventual search results. it should also be noted that the covered periods of reviewed articles were slightly different between academic and practical approach (ending with dec 31, 2016 and with march 27, 2017, respectively). we believe that the resulting differences in the included sample of research articles would not have substantially altered our findings. the search engine that is used will as well have an effect on the results. not only do search engines employ different methods to determine which articles to display first, but not all search engines index all journals. for example, pubmed, a search engine used to retrieve data from medline, the national library of medicine journal citation database,12 has are not yet indexed jpo articles.13 accordingly, there are a few recommendations that prosthetists should consider when going through the process of implementing ebp into their clinical practices. practitioners in our field should select scholarly search engines/literature databases that work best for the questions they wish to answer and be aware of the journals indexed in those databases. it is also worth considering that while an article may be inaccessible on one website, it may be freely accessible on another. consulting the publishing journals’ websites can be helpful to determine a research article’s accessibility. while strategies exist that can help prosthetists better search for articles and overcome accessibility issues, the effort to learn and employ those strategies is still part of the initially mentioned barrier that needs to be overcome to properly implement ebp. nonetheless, compared with the pre-internet necessity of frequenting a university library to sift https://doi.org/10.33137/cpoj.v1i1.30009 burke j, fiedler g. clinicians’ access to peer-reviewed prosthetics research articles. canadian prosthetics & orthotics journal, volume 1, issue 1, no 3, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30009 6 open access clinicians’ access to peer-reviewed prosthetics research articles volume 1, issue 1, article no. 3, august 2018 through physical copies of countless journals for a literature review, this small barrier should not discourage prosthetists or dissuade them from conducting a proper evidence search. it is possible that other barriers that are commonly cited as an impediment to ebp are not as substantive as they are perceived either. future research may be recommendable that investigates the true effects of time constraints, clinical relevance of scientific publications, and lacking incentives have on p&o practitioners’ attitude toward implementation of ebp in their daily work. conclusion we found that about 75% of research articles in the field of prosthetics are freely available online. whether this is indeed a big enough ratio to facilitate ebp in most cases should be investigated in future research, utilizing a more accurate simulation of recommended practical approaches to ebp and analyzing the outcomes across a larger sample of cases and practitioners. author contribution • julie burke: conceptualization, study design, initial literature search and analysis, manuscript draft. • goeran fiedler: study oversight, secondary literature search and analysis, manuscript editing and revision. declaration of conflicting interests the authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. references 1.geil md. assessing the state of clinically applicable research for evidence-based practice in prosthetics and orthotics. journal of rehabilitation research and development. 2009; 46: 305-13. doi:10.1682/jrrd.2008.02.0019 2. ramstrand n. translating research into prosthetic and orthotic practice. prosthetics and orthotics international. 2013; 37: 108-12. https://doi.org/10.1177/0309364612451268 3. ramstrand n, brodtkorb th. considerations for developing an evidenced-based practice in orthotics and prosthetics. prosthetics and orthotics international. 2008; 32: 93-102. https://doi.org/10.1080/03093640701838190 4. stevens pm. barriers to the implementation of evidence-based practice in orthotics and prosthetics. journal of prosthetics and orthotics. 2011; 23: 34-9. doi: 10.1097/jpo.0b013e3182064d29. 5. walters hn, custis dl, boren hg, giannini mj, todd, jr sp. five editorials. the journal of rehabilitation research and development. 1983; 20(1): 1-2. 6. jrrd to cease publication. the o&p edge. northglenn, co 80234: western media llc, 2016. [available at: https://opedge.com/articles/viewarticle/news_2016-0707_03] accessed august 4, 2018. 7. eshraghi a, osman naa, gholizadeh h, ali s, shadgan b. 100 top-cited scientific papers in limb prosthetics. biomedical engineering online. 2013; 12: 119. https://doi.org/10.1186/1475-925x-12-119 8. burke j, fiedler g. p&o professionals’ access to peerreviewed research articles. 44th annual aaop meeting and scientific symposium. new orleans, la, 2018. 9. baldwin va. using google scholar to search for online availability of a cited article in engineering disciplines. 2009. [available at: https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article =1192&context=libraryscience] accessed august 4, 2018. 10. burke j, fiedler g. online access to research papers – changes over time. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018, abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. https://doi.org/10.33137/cpoj.v1i2.32010 11. kahle jt, highsmith mj, hubbard sl. comparison of nonmicroprocessor knee mechanism versus c-leg on prosthesis evaluation questionnaire, stumbles, falls, walking tests, stair descent, and knee preference. journal of rehabilitation research and development. 2008; 45: 1. doi: 10.1682/jrrd.2007.04.0054. 12. factsheet. medline, pubmed, and pmc (pubmed central): how are they different. 2018. [available at: https://www.nlm.nih.gov/bsd/difference.html] accessed august 4. 2018. 13. miro rm, lewandowski al, kahle jt, mengelkoch lj, boone da, highsmith mj. bibliometric analysis of articles published from 2009 through 2011 in the journal of prosthetics and orthotics, journal of the american academy of orthotists and prosthetists. journal of prosthetics and orthotics. 2013; 25: 201-8. doi: 10.1097/jpo.0000000000000007. https://doi.org/10.33137/cpoj.v1i1.30009 https://www.rehab.research.va.gov/jour/09/46/3/geil.html https://www.rehab.research.va.gov/jour/09/46/3/geil.html https://doi.org/10.1177/0309364612451268 https://doi.org/10.1080/03093640701838190 https://journals.lww.com/jpojournal/fulltext/2011/01000/barriers_to_the_implementation_of_evidence_based.8.aspx https://journals.lww.com/jpojournal/fulltext/2011/01000/barriers_to_the_implementation_of_evidence_based.8.aspx https://doi.org/10.1186/1475-925x-12-119 https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1192&context=libraryscience https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1192&context=libraryscience https://doi.org/10.33137/cpoj.v1i2.32010 https://www.rehab.research.va.gov/jour/08/45/1/kahle.html https://www.nlm.nih.gov/bsd/difference.html https://journals.lww.com/jpojournal/fulltext/2013/10000/bibliometric_analysis_of_articles_published_from.9.aspx https://journals.lww.com/jpojournal/fulltext/2013/10000/bibliometric_analysis_of_articles_published_from.9.aspx dillingham t.r, kenia j, shofer f.s, marschalek j. an immediate fit and adjustable transtibial prosthetic system; a prospective feasibility and efficacy study. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018.doi: https://doi.org/10.33137/cpoj.v1i2.32025 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) an immediate fit and adjustable transtibial prosthetic system; a prospective feasibility and efficacy study timothy r. dillingham1, jessica kenia1*, frances s. shofer2, jim marschalek3 1department of physical medicine and rehabilitation, university of pennsylvania school of medicine; philadelphia, pa, usa. 2department of emergency medicine, university of pennsylvania school of medicine; philadelphia, pa, usa. 3advanced design concepts, pewaukee, wi, usa. * email: jessica.kenia@uphs.upenn.edu doi: https://doi.org/10.33137/cpoj.v1i2.32025 introduction limb loss rates globally are rising and there is a large unmet need for an affordable and accessible prosthetic system for this growing us and international population. the purpose of this prospective cohort study was to assess the feasibility and utility of a novel immediate fit modular prosthetic system (ifit prosthetics, llc™ prosthesis) for transtibial amputees. methods transtibial amputees at least 6 months post amputation currently using a conventional prosthesis were enrolled after full consent under an irb approved protocol. they were excluded if they had skin wounds, excessive limb or phantom pain, and a neurological disorder that interfered with gait. the pi fit and aligned all devices. the participants were instructed to wear the prosthesis for a two-week evaluation period in order to compare it to their own device. a questionnaire based off the prosthetic evaluation questionnaire (peq) was given on their current device during their first visit and they evaluated the ifit prosthesis during the follow up visit. a gait biomechanical analysis and pressure evaluations (fujifilm prescale®) were conducted. all adverse events or mechanical issues were recorded. results twenty-six participants agreed to participate in the trial. twenty-two amputees completed the study, with four not willing to travel for follow up. mean age for subjects completing the study was 51.1, sd ±11.3 years, with 3 females and 19 males enrolled. fourteen were dysvascular amputees and eight had traumatic etiologies. a significant difference in self-reported satisfaction was found for the ifit device 29.33, sd ± 4.51 versus mean score for own device = 25.52, sd ± 6.8 (p= 0.0323) (table 1). no falls or limb ischemia were reported. two people had minor skin breakdown that resolved with realigning and altering socket liner. gait biomechanics revealed no differences in any temporal values. pressures were significantly lower in the ifit prosthesis versus a conventional prosthesis p = .0014 and at anterior tibia p=.0002, and lateral side p=.013 (figure 1). discussion the ifit prosthesis compared favorably to subjects’ conventional prostheses in terms of self-reported satisfaction and gait. intra-socket pressures were lower than in conventional devices. the ifit device demonstrated safety and efficacy in this prospective trial. mailto:jessica.kenia@uphs.upenn.edu https://doi.org/10.33137/cpoj.v1i2.32025 dillingham t.r, kenia j, shofer f.s, marschalek j. an immediate fit and adjustable transtibial prosthetic system; a prospective feasibility and efficacy study. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018.doi: https://doi.org/10.33137/cpoj.v1i2.32025 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) with its potential cost and accessibility advantages, the ifit prosthetic system holds promise to enhance access for transtibial amputees. figure 1. average peak pressure: ifit versus conventional prosthesis. an estimated pressure in pounds/square inch (psi) is indicated next to the mean values and reflects an estimated pressure as determined through nomographic scoring (fujifilm ). these are peak pressures that occurred with ambulation. conclusion the ifit transtibial prosthetic system is safe and effective in this short term trial. a larger multicenter comparative effectiveness study is needed to confirm these findings. acknowledgment this study was funded by the national institutes of health, national institute on aging (grants: 2sb1ag050430-06 and 2r42ag050430-04) and the nichd and ncmrr (grants 2r42 hd 069067-02 and 1r41hd069067 – 01). dr. dillingham founded the company ifit prosthetics, llc® and is the major owner and director. patient testing occurred at the university of pennsylvania under sub-contact and included a provost conflict of interest management plan for the pi. disclaimer and conflict of interest statement the pi founded the company ifit prosthetics, llc and is the major owner and director. he has financial interest in the prosthetic system being presented in this article. he signed nih compliant conflict of interest management agreements with the university where research was conducted. lemaire ed, supan t, ortiz m. global standards for prosthetics and orthotics. canadian prosthetics & orthotics journal. volume1, issue2, no.3, 2018. https://doi.org/10.33137/cpoj.v1i2.31371 professional opinion issn: 2561-987x all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x volume 1, issue 2 2 0 1 8 https://doi.org/10.33137/cpoj.v1i2.31371 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com lemaire ed, supan t, ortiz m. global standards for prosthetics and orthotics. canadian prosthetics & orthotics journal. volume1, issue2, no.3, 2018. https://doi.org/10.33137/cpoj.v1i2.31371 1 open access global standards for prosthetics and orthotics volume 1, issue 2, article no.3, october 2018 professional opinion global standards for prosthetics and orthotics lemaire ed1,2*, supan t3, ortiz m4 1ottawa hospital research institute, centre for rehabilitation research and development, ottawa, canada. 2faculty of medicine, university of ottawa, ottawa, canada. 3supan prosthetic orthotic consultations, rochester, illinois, usa. 4ortiz international s.a. guadalajara, jalisco, méxico. the 60 new global “standards for prosthetics and orthotics”1 were developed to: • support countries work to “strengthen and extend rehabilitation, habilitation, assistive products, support services and communitybased rehabilitation”2, from the “who global disability action plan” • achieve the eight recommended areas of rehabilitation in health systems from “rehabilitation 2030: call for action”3 • achieve who gate4 initiative goals, to improve access to high-quality, affordable assistive products globally • realize universal health coverage • support countries implementing crpd, particularly article 20 (personal mobility) and article 26 (habilitation and rehabilitation) universal health coverage is often confused with fully socialized healthcare. for the standards, the who definition applies: “ensuring that all people can use the promotive, preventive, curative, rehabilitative and palliative health services they need, of sufficient quality to be effective, while also ensuring that the use of these services does not expose the user to financial hardship.” this does not impose a health service funding or organizational model to achieve these goals. these standards are for prosthetics and orthotics services, using a people centred care perspective. therefore, the scope is beyond the prosthetist and orthotist, including devices that may be provided by other health care professionals with the right skills (i.e., physicians, nurses, physiotherapists, occupational therapists, pedorthotists, pedorthists, podiatrists). internal prostheses are not covered (e.g., joint implants, dental prostheses). peoplecentred care includes psychosocial aspects that strengthens personal identity, enhances well-being, and recognizes the importance of social interactions. the standards are divided into four sections: policy, products (prostheses, orthoses), personnel, provision of services. challenges are addressed in the standards and implementation manual: *corresponding author edward d lemaire, ottawa hospital research institute, centre for rehabilitation research and development, 505 smyth road, ottawa, on, canada, k1h 8m2. 613-737-7350 x75592 email: elemaire@ohri.ca doi: https://doi.org/10.33137/cpoj.v1i2.31371 citation lemaire ed, supan t, ortiz m. global standards for prosthetics and orthotics. canadian prosthetics & orthotics journal. volume1, issue2, no.3, 2018. https://doi.org/10.33137/cpoj.v1i 2.31371 keywords prosthetics, orthotics, disabilities, world health organization. over the past decade, essential documents and agreements have emerged to help improve the lives of people with physical disabilities. these include convention on the rights of persons with disabilities (crpd), ratified by more than 170 countries, and the world health organization (who) global disability action plan. while the principles in these broad agreements can be applied to people who would benefit from assistive technology, specific service standards are required to operationalize the crpd and who objectives. therefore, who, in partnership with the international society for prosthetics and orthotics (ispo) and the united states agency for international development (usaid), prepared global standards and an implementation manual to assist member states in setting up, improving, or transforming their systems for delivering appropriate prosthetic and orthotic services. https://doi.org/10.33137/cpoj.v1i2.31371 mailto:elemaire@ohri.ca https://doi.org/10.33137/cpoj.v1i2.31371 https://doi.org/10.33137/cpoj.v1i2.31371 https://doi.org/10.33137/cpoj.v1i2.31371 lemaire ed, supan t, ortiz m. global standards for prosthetics and orthotics. canadian prosthetics & orthotics journal. volume1, issue2, no.3, 2018. https://doi.org/10.33137/cpoj.v1i2.31371 2 open access global standards for prosthetics and orthotics volume 1, issue 2, article no.3, october 2018 policy • absence of policies and national plans for prosthetics and orthotics, rehabilitation, and assistive technology in most countries • lack of awareness and understanding about the role, purpose, and benefits of prosthetics and orthotics services • limited funding, with services frequently not included in national health and social insurance systems • limited data on needs for these services, making it difficult to understand the practical and financial requirements of providing such services for all products • limited availability of appropriate products in many countries • high price of high-quality prostheses and orthoses o even low-cost alternatives may be perceived as expensive, particularly in lowand middleincome countries • lack of national product standards in many countries, often resulting in devices that do not meet acceptable safety standards • limited evidence of the effectiveness and cost– effectiveness of products, technologies, and working methods personnel • lack of qualified personnel, reducing the quality and quantity of services • available personnel are usually found in large cities • limited access to schools and training opportunities for prosthetics and orthotics provision of services • unequal service provision, with services are frequently available only in capital and other large cities and not to poor, isolated populations in rural areas • services for the poor are usually provided by charities and some government institutions, which may offer poor quality products, while rich populations are frequently served by private clinics • prosthetics and orthotics services are frequently perceived as an expense rather than an investment policy (15 standards) governments are encouraged to take a lead role in bringing stakeholders together and developing a national approach for prosthetics and orthotics services, moving beyond policy to include planning, implementation, and monitoring. an interesting standard (s3) recommends a national prosthetics and orthotics committee or similar entity, which would benefit both high and low-income countries, leading to a national guiding framework (s4). regulation is also recommended (s5), which is typically not the situation for prosthetics and orthotics (i.e., typically certification, which does not have the same legal status, or no legal status). the need to monitor and have international sharing of experience, data, and research is recognized as essential for advancing services globally. standards s13-s14 specifically address the need for data to enable decision-making. cost and funding of prosthetics and orthotics are addressed in standards s9 to s12. the need to have prosthetics and orthotics services considered “like other health interventions” is critical to achieve appropriate funding, and to enable cost-related factors that enable broad access. for example, why is prosthetic and orthotic funding considered differently from hip and knee replacement funding? products (9 standards) this important section addresses prosthetic and orthotic products, which is the most visible aspect of prosthetic and orthotic care. standards s16-s18 include the availability and range of devices available in the local region and standards s19-s20 relate to components and materials. the ongoing discussion about the value of reusing components leads to the recommendation for regulation by a designated authority or “expert group” with no conflicts of interest, which would include issues such as black markets and resale as new, and quality control with documentation. the quality control and documentation aspects for reuse is often neglected or is handled on the organizational or business level instead applying broader requirements for audited documentation. technical standards (s21-s22) are important for national and international (international organization for standardization (iso), etc.) bodies to ensure sufficient products quality and safety for consumers. national regulation of prosthetic and orthotic products, components, and materials is a step beyond most country’s approach, where https://doi.org/10.33137/cpoj.v1i2.31371 lemaire ed, supan t, ortiz m. global standards for prosthetics and orthotics. canadian prosthetics & orthotics journal. volume1, issue2, no.3, 2018. https://doi.org/10.33137/cpoj.v1i2.31371 3 open access global standards for prosthetics and orthotics volume 1, issue 2, article no.3, october 2018 minimal requirements are in place for this medical device category and nothing is in place for the complete device. research related standards (s23-s24) include the need to develop affordable prosthetic and orthotic products that are cost–effective, of good quality, and context appropriate; which is different from trying to make the least expensive device, with subsequent lower quality. these research standards are related to the policy standards for data and sharing knowledge. personnel (12 standards) the personnel standards recognized the importance of having appropriate trained and competent professionals, within a multidisciplinary team for complex cases, provide prosthetic and orthotic care. training should not only be aligned nationally but also with international education standards. continuing professional development is considered compulsory. to meet this need, widely accessible learning opportunities will need to be developed, and continually updated, to match the pace of assistive technology advancement. workforce planning (s31-s33) should not only deal with recruiting and retaining appropriate service providers but should recognize “all the disciplines required in prosthetics and orthotics services at all levels”. this approach moves beyond the simple training of prosthetists and orthotists to involving national stakeholders to ensure a workforce that has local context and can be made available (i.e., flexible workforce that adapts to changing conditions). this flexibility remains a challenge in most regions. the standards for professional regulation and recognition deal with accountability and career structure. as the world moves to address global assistive technology issues (fitting 1 billion people in need), maintaining quality services will require health care professionals, associates, and technical personnel with clearly define roles and responsibilities. the alignment of prosthetists and orthotists within the scope of health professionals remains problematics and requires global effort to achieve appropriate positioning. this is critical for the evolving “associate” level practitioner where responsibilities could be expected to vary depending on the country and circumstance (i.e., larger scope in developing or crisis area). provision of services (24 standards) to achieve user-centred service delivery, the standards endeavour to promote services where “every user with a physical impairment or functional limitation can make informed decisions about her or his care, services, and service providers”; and “services are planned from the perspective of the individual user and respond to her or his needs and preferences, respecting their dignity, choices and rights.” the standards recommend documented policy to safeguard the rights of users, involving service users and their representatives at all levels, and providing choice for service providers and technology. to achieve this vision, service delivery models should facilitate accessibility (s40), be part of the health system (s41,s45,s46), be delivered as a 3tier system (s42), and consider maintenance and repair as part of the service (s43). standards 47 and 48 address the service environment, recommending service provision in a user-friendly, barrier-free, safe, clinical environment that is properly equipped. service delivery is divided into four steps (assessment, fabrication and fitting, user training and product delivery, follow-up) that are covered in nine standards. evidence based practice and care documentation are essential. user centre care principles are included throughout these four steps. quality management approaches should be used, with annual and long-term planning supported by continuous monitoring of performance indicators. consideration prostheses and orthoses in disaster conditions (s44) is an interesting standard since the attention to services may not be included in many country’s disaster plans, especially since prosthetic and orthotic care is a long-term (lifetime) service requirement and thereby requires different planning considerations than acute care needs. implementation the accompanying implementation manual provides detailed ideas and examples of how each standard can be operationalized. of these, the following items are of particular interest: stakeholders: a broad approach should be considered when engaging people and groups. a list of stakeholders and their roles are provided, and https://doi.org/10.33137/cpoj.v1i2.31371 lemaire ed, supan t, ortiz m. global standards for prosthetics and orthotics. canadian prosthetics & orthotics journal. volume1, issue2, no.3, 2018. https://doi.org/10.33137/cpoj.v1i2.31371 4 open access global standards for prosthetics and orthotics volume 1, issue 2, article no.3, october 2018 can be used to engage with these people or groups (i.e., ask why a group is not engaged when they are identified in the standards) national approach: in most countries, at least one of the standards or implementation ideas is likely lacking; for example, having a government supported prosthetic and orthotic committee with a 5–10-year plan that is specific, measurable, achievable, realistic, and timely a national audit of how each country currently adheres to the standard, with global reporting to allow for inter-country benchmarking, is an important step to understand deficiencies and successes. this information will empower country and global regions to advocate and achieve positive change for prosthetic and orthotic services data and evidence: implementing positive change requires solid evidence. with the many players involved with provision (public, private, hospital, military, etc.) and funding, new strategies are required to obtain quantitative evidence on costs and economic impact; best practices; products; human resources; unmet needs research: the need for continued research is apparent, but the standards reiterate the need for global collaboration (project formulation, multicountry studies, etc.) and sharing to make the best use of this research, thereby expanding the evidence base on prosthetics and orthotics services. these global factors include identifying and standardizing research questions, using standardized tools, increasing research-related investment, and broadening the range of experts involved with prosthetic and orthotic related research (e.g., health economists, human rights experts, policy analysts, etc.). these who global standards for prosthetic and orthotic services are important for enhancing understanding of the expectation for appropriate care, regardless of the person’s location or economic status. as with any standards, success is directly related to how they are applied. with local, national, and international efforts, positive change can be realized to deal with the current state of only 1 in 10 people in need having access to assistive products, thereby “helping people to become more active and to live healthy, productive, independent, dignified lives and to participate in education, the labour market and social life”. references 1. who standards for prosthetics and orthotics. geneva: world health organization; 2017 (http://www.who.int/rehabilitation/prosthetics-and-orthoticsstandards/en/, accessed 31 october 2018). 2. who global disability action plan 2014–2021. better health for all people with disability. geneva: world health organization; 2015 (http://www.who.int/disabilities/actionplan/en/, accessed 31 october 2018). 3. rehabilitation 2030. a call for action. geneva: world health organization; 2017 (http://www.who.int/disabilities/care/rehab-2030/en/, accessed 31 october 2018). 4. global cooperation on assistive technology (gate). geneva: world health organization; 2016 (http://www.who.int/phi/implementation/assistive_technolo gy/phi_gate/en/, accessed 31 october 2018). authors biography professor edward lemaire, president-elect of ispo edward lemaire, phd, is actively involved with research on technologies that improve mobility for people with physical disabilities. he is a senior investigator at the ottawa hospital research institute’s centre for rehabilitation research and development; professor at the university of ottawa faculty of medicine; and adjunct professor in human kinetics, mechanical engineering, and systems design engineering. he is also active with the international society of prosthetics and orthotics, as a board member, international congress chairman, and incoming president. dr. lemaire’s research has resulted in over 450 published papers and presentations that include intelligent prosthetics and orthotics, biomechanical walking analysis in 3d virtual environments, smartphone approaches to improve decision-making, and ehealth technology to enhance access to education and rehabilitation services. terry j supan, cpo, lpo, fispo, faaop terry j. supan, is president and ceo of supan prosthetic orthotic consultations. he is a clinical professor (retired) at southern illinois university school of medicine and a former chair of the illinois orthotic, prosthetic and pedorthic licensure board. he is a licensed and board certified orthotist and prosthetist that specialized in upper limb amputations, cerebral palsy, scoliosis, polio, stroke, and other rehabilitation for persons with physical disabilities. he is an internationally known speaker in those areas as well as lower https://doi.org/10.33137/cpoj.v1i2.31371 lemaire ed, supan t, ortiz m. global standards for prosthetics and orthotics. canadian prosthetics & orthotics journal. volume1, issue2, no.3, 2018. https://doi.org/10.33137/cpoj.v1i2.31371 5 open access global standards for prosthetics and orthotics volume 1, issue 2, article no.3, october 2018 limb prosthetics; biomechanics/gait analysis; prosthetic/orthotic education; state o&p practice acts; and governmental regulations. mr. supan served as the president of the american academy of orthotists and prosthetists’ (aaop) in 1990 -1991. on march 22nd, 2012 the academy bestowed the titusferguson lifetime achievement award on mr. supan. he is a fellow of both the aaop and the ispo. in june of 2015 he was appointed to the international society for prosthetics and orthotics executive board and serves as the treasurer of ispo. he was re-elected as ispo treasurer in 2017 and will serve in that capacity until 2019. marlo ortiz marlo ortiz graduated as an engineer in 1977 from university of guadalajara, mexico and later undertook courses in prosthetics and orthotics until 1979, when he began to practice as a certified clinical prosthetist (barra mexicana de certificacion en ortesis y protesis a.c.). he was recipient of the “clinical creativity” prize presented at the 2005 aaop meeting in orlando and “blatchford prize” for best “prosthetic technology” at the ispo 2007 world congress in vancouver. marlo ortiz is an international speaker with o&p presentations at meetings in many countries for over 20 years. he is also national coordinator of uniting frontiers regional board, international representative of ispo mexico national member society, and member of the executive board of ispo international. https://doi.org/10.33137/cpoj.v1i2.31371 sabeti s, raschke s.u, mattie j. the effect of material choice and process parameters on the mechanical strength of 3d-printed transtibial prosthetic. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32160 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) the effect of material choice and process parameters on the mechanical strength of 3d-printed transtibial prosthetic shadi sabeti1, silvia ursula raschke*2, johanne mattie2 1 british columbia institute of technology (bcit), burnaby, british columbia, canada. 2 make + applied research, centre for applied research & innovation (cari), burnaby, british columbia, canada. * email: silvia_raschke@bcit.ca doi: https://doi.org/10.33137/cpoj.v1i2.32160 introduction the most important aspect of a lower extremity prosthesis is the socket. the socket is the interface between the human and the mechanical support system1. there are different methods for producing prosthetic sockets. the traditional method requires a skilled prosthetist and is time consuming 2, 3. using 3d printing technology for manufacturing prosthetic sockets promises to speed up the fabrication process and reduce materials and time cost significantly. 3d printed prosthetic sockets have to potential to increase socket strength and durability. this paper investigates the effect of material choices and printing process parameters on the mechanical strength of 3d printed trans-tibial sockets. methods first available printable materials with excellent structural characteristics were identified. nylon 12, recycled nylon 12, and pla were selected. the appropriateness of 3d printed prosthetic sockets lies in its strength and durability of the sockets. 3d printing parameters that have impact on the mechanical properties of printed sockets were explored as well. two additive manufacturing methods, namely fused deposition modeling (fdm) and selective laser sintering (sls) were selected. based on selected materials and manufacturing methods seven prototype sockets were fabricated. a standard socket attachment block and orthocryl sealing resin was used to connect the socket and pylon. iso standard 10328 was used to statically evaluate the strength of printed sockets. as specific guidelines for trans-tibial socket testing had yet to be stablished the loading parameters and offset values for lower limb prostheses were used. a tinius olsen universal testing machine was used to test the seven sockets by applying vertical loads under static condition during early stance phase of gate cycle for an 80 kg transtibial male amputee patient. each socket was tested for a proof test and ultimate strength test and then loaded to failure in accordance with the iso standard 10328. results after applying the loads for loading condition i and load level p4 specified in the standard, all sockets were loaded until failure. the maximum load reached in every socket can be seen in figure 1. both of the unrecycled nylon 12 sockets resulted in the failure of the socket attachment system. figure 1: ultimate strength at failure for different socket types. n: nylon12, p: pla, rn: recycled nylon 12. in general, all the unrecycled and recycled nylon 12 printed sockets met the minimum iso standard for ultimate strength. however, recycled nylon 12 performed with lower ultimate strength than did unrecycled nylon 12. the remaining two systems, the pla sockets that was printed in xz direction, resulted in the failure of the socket before reaching the ultimate strength specified in iso standard. conclusion this pilot study results showed that the pla socket tested do not meet the minimum requirement of the iso 10328. all nylon 12 printed socket tested exceeded ultimate strength for iso 10328. for two of the socket tested the attachment block failed before the socket 0 5000 10000 15000 20000 n1 n2 p1 p2 rn1 rn2 rn3 l o a d ( n ) socket type mailto:silvia_raschke@bcit.ca https://doi.org/10.33137/cpoj.v1i2.32160 sabeti s, raschke s.u, mattie j. the effect of material choice and process parameters on the mechanical strength of 3d-printed transtibial prosthetic. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32160 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) failed. therefore, it’s recommended that additional study for determining a suitable method for attaching adaptor to socket are needed. acknowledgments the authors gratefully acknowledge the assistance of barber prosthetic clinic, wiivv wearables, and yamagata university, who contributed their time and materials to make this project successful. references 1. foort j. et.al. experimental fittings of sockets for belowknee amputees using computeraided design and manufacturing techniques, prosthetics & orthotics international. 1985; 9:46-47. doi:10.3109/03093648509164824 2. radcliffe d.f. computer-aided rehabilitation engineeringcare. journal of medical engineering & technology. 1986; 10:16. 3.stakosa, j.j. prosthetics for lower limb amputees, vascular surgery: principles and techniques, norwalk, ct, appletoncentury-crofts. 1984;1143-1162. https://doi.org/10.3109/03093648509164824 stark g e. factor analysis of upper limb prosthetic acceptance from retrospective prosthetic clinician survey. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32045 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) factor analysis of upper limb prosthetic acceptance from retrospective prosthetic clinician survey gerald e. stark school of biological sciences, georgia institute of technology, georgia, usa. email: gerald.e.stark@gmail.com doi: https://doi.org/10.33137/cpoj.v1i2.32045 introduction upper limb prosthetic acceptance seems to be relatively unchanged from 1958 where it was measured to be 75% for transradial, 61% for transhumeral, and 35% for shoulder disarticulation levels. a practitioner survey from 2013 by the author found this to be largely unchanged at 79.6%, 57.8%, and 32.8% respectively. an upper limb meta-analysis showed that the most significant factors affecting prosthetic rejection using a median rating were function, comfort, ease of use, weight, heat, lack of sensory feedback, inconvenience, lifestyle, dissatisfaction with technology, irritation, and availability of services. an earlier survey by the author condensed these factors of rejection to amputation level, functional advantage, and comfort, and included confidence of the prosthetist, availability of therapy, and support of the patient context. also it was speculated that the value of factors influencing rejection of prostheses may not be simply the converse of those accepting the prosthesis but different scales. methods a retrospective case survey was created using a thirdparty web-based survey provider that was posted from 3/15/17 to 4/1/17 using postings on the oandp listserv to recruit participants. prosthetists were asked to recall up to their last three upper limb fittings. there were 75 respondents with 209 retrospective cases. based on the number of ul fitting, participants were participants classified: 12 specialists, 20 experts, 27 intermediates, and 16 novices. the participants were asked to assess various retrospective factors including prosthetic level, type of control, patient gadget tolerance, patient functional expectation, comfort tolerance, patient value of cosmesis, confidence of prosthetist, availability of therapy, experience level of therapist, daily wear time, patient description of prosthesis, and patient assessment of cosmetic quality. by level the distribution was 24 finger/transcarpal, 17 wrist disarticulation, 110 transradial, 4 elbow disarticulation, 47 transhumeral, 6 shoulder disarticulation, and 1 interscapular thoracic reflecting a common distribution. body power control predominated with 84 and external power as 72 with passive at 27, and hybrid control at 26. results the clinician self-assessments predominantly showed highly favorable, and perhaps skewed, outcomes with respect to functional expectation, gadget tolerance, prosthetic confidence, contextual support, patient wear time, patient proficiency, cosmetic acceptance, and description of the prosthesis. areas of more normalized distribution appeared to be upper limb experience for therapists, patient experience, and prosthetic description. using pearson’s coefficient, there were statistically significant relationships at p (one-tailed)<.01 level between the patient acceptance level and patient experience, gadget tolerance, functional expectation, comfort tolerance, prosthetist confidence, and patient cosmetic description and a negative p<.05 relationship with experience of the therapist. the relationships were true of the number of hours worn. a very strongly predictive relationship of r2 linear = .564 f(10,197) = 25.513 with all of the factors listed above. however a systematic multi-variable reduction found a strong significance, r2linear =.556, f(3,204) = 85.302, with the patient acceptance level, gadget tolerance, patient experience, which may not have practical clinical relevance. discussion the skewed distribution of prosthetist self-assessment for functional expectation, gadget tolerance, comfort, prosthetic confidence, contextual support, and patient proficiency, wear time, and prosthetic description of this retrospective may be indicative of a group halo or optimism bias. also this calls into question the validity and reliability of the sample and relevance to the application. however, the negative relationship between the expertise of therapist and proficiency of the patient may indicate that the therapist may mitigate this bias and mailto:gerald.e.stark@gmail.com https://doi.org/10.33137/cpoj.v1i2.32045 stark g e. factor analysis of upper limb prosthetic acceptance from retrospective prosthetic clinician survey. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32045 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) influence a clearer understanding of functional outcome. the strong statistically predictive relationship between the 10 identified factors suggests these may provide an indicator of acceptance. however additional direct patient understanding seems to be needed to draw a narrower focus as to the most significant factors for clinical use. conclusion more research needs to be done directly done with upper limb prosthetic users with respect to acceptance rather than the convenience sample of prosthetists. as a group, clinicians seem to present a higher assessment of their abilities due to an optimism bias. external evaluation by a therapist seems crucial to understanding true patient functional performance however, this current work may help to establish which factors seem to have the greatest relationship for acceptance for subsequent research. references berger, n. studies of the upper extremity amputee ii. the population (1953-55) artificial limbs. 1958; 5 (1), p. 57-72. biddess, e., chau, t. (2007). upper limb prosthetics: critical factors in device abandonment. am j phys med rehabil. 2007; 86, p. 977-987. doi:10.1097/phm.0b013e3181587f6c stark, g. factor analysis of upper extremity prosthetic patient acceptance. paper presented at the american orthotic and prosthetic association national meeting, las vegas, nevada, 2014. burrough, s., brook, j. patterns of acceptance and rejection of upper limb prostheses. orthotics and prosthetics, 1985, 39(2), p. 40-47. https://doi.org/10.1097/phm.0b013e3181587f6c kannenberg a. evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation: a mini literature review. canadian prosthetics & orthotics journal, volume 1, issue 1, no. 6, 2018, doi: https://doi.org/10.33137/cpoj.v1i1.30450 literature review issn: 2561-987x all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x volume 1, issue 1 2 0 1 8 https://doi.org/10.33137/cpoj.v1i1.30450 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com kannenberg a. evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation: a mini literature review. canadian prosthetics & orthotics journal, volume 1, issue 1, no. 6, 2018, doi: https://doi.org/10.33137/cpoj.v1i1.30450 1 open access evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation volume 1, issue 1, article no. 6, september 2018 literature review evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation: a mini literature review. andreas kannenberg* executive medical director north america, department of medical affairs, otto bock healthcare, austin, tx, usa. introduction microprocessor technology has been adopted in prosthetic knees for almost 30 years and in prosthetic feet for about 10 years. several systematic reviews of the literature on microprocessorcontrolled knees have confirmed their benefits in safety and mobility, supporting their use in individuals with transfemoral amputation and mfcl3 and also mfcl-2 mobility. however, microprocessor-controlled (mp) passive and powered feet are widely considered experimental, investigational and unproven by health insurances. method the medline and embase databases as well as the online library of the journal of prosthetics and orthotics were searched on january 15, 2018, for publications using search terms related to feet with non-mp hydraulic ankles/dorsiflexion feature, or passive or powered microprocessor controlled feet. citation kannenberg a. evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation: a mini literature review. canadian prosthetics & orthotics journal, volume 1, issue 1, no. 6, 2018. doi: https://doi.org/10.33137/cpoj.v1i1.30 450 keywords prosthetic feet, microprocessor control, active ankle power, active dorsiflexion, powered ankles, passive microprocessor, medline, rehabilitation, prosthetics. abstract this paper reviewed 11 publications on non-mp controlled ankles with active dorsiflexion feature, 15 publications on passive mp controlled ankles, and 12 publications on powered mp controlled ankle-foot mechanisms. methodological quality of publications was low to moderate. the evidence found was mostly biomechanical and generated in gait lab studies. non-mp ankles may increase toe clearance and reduce braking forces during level walking, thus supporting propulsion with increase in walking speed. passive mp controlled ankles may also increase toe clearance and reduce the likelihood of stumbling over an unseen obstacle. they may reduce energy expenditure during level walking and facilitate slope and stair ambulation. non-mp and passive mp controlled ankles have been also been shown to reduce residual limb-socket interface pressures. powered ankles may increase walking speed to the level of and decrease energy expenditure to be no longer significantly different from that of able-bodied individuals. also, at higher walking speeds the sound knee loading may be reduced by up to 1520%. however, it remains unclear to what extent the gait lab results for all advanced ankle-foot mechanisms can be transferred to real-life benefits in the free-living environment. article info received: july 23, 2018 accepted: august 29, 2018 published: september 1, 2018 *corresponding author: dr. andreas kannenberg, executive medical director north america, department of medical affairs, otto bock healthcare, austin, tx, usa. email: andreas.kannenberg@ottobock.com doi: https://doi.org/10.33137/cpoj.v1i1.30450 https://doi.org/10.33137/cpoj.v1i1.30450 https://doi.org/10.33137/cpoj.v1i1.30450 https://doi.org/10.33137/cpoj.v1i1.30450 mailto:andreas.kannenberg@ottobock.com https://doi.org/10.33137/cpoj.v1i1.30450 kannenberg a. evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation: a mini literature review. canadian prosthetics & orthotics journal, volume 1, issue 1, no. 6, 2018, doi: https://doi.org/10.33137/cpoj.v1i1.30450 2 open access evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation volume 1, issue 1, article no. 6, september 2018 the search terms were combined into a title, abstract, and key word search phrase using boolean operators, resulting in the following syntax: amput* or prosth* and foot or ankle or hydraulic or dorsiflexion or linkage or microprocessor or mp* or power*. the literature search was repeated on june 30, 2018, to identify recent publications since the original search date. titles and abstracts of the identified publications were screened for their scope. technical papers and case studies were excluded. publications on biomechanical and clinical studies were rated for methodological quality using the criteria of a cochrane review of prosthetic foot research by hofstad et al.1 publications with good enough methodological quality were reviewed in full and results were extracted and summarized. results the literature search yielded 12 publications (reference 2-13) on biomechanical and/or clinical studies with a prosthetic foot with a non-mp controlled hydraulic ankle/dorsiflexion feature, 16 publications (reference 14-29) on passive and 17 publications (reference 30-46) on powered mp controlled prosthetic ankle-foot mechanisms. one publication on non-mp feet (12), one publication on passive mp feet (14) and 5 publications on powered ankle-foot mechanisms (35, 40, 44-46) were excluded from the review for insufficient methodological quality. all included studies had low to moderate methodological quality and all but one were conducted with individuals with unilateral transtibial amputations. compared to standard energy storage and return (esar) feet, the studies with a foot with a non-mp hydraulic ankle/dorsiflexion feature demonstrated a significantly increased toe clearance and self-selected walking speed on level ground. in addition, studies reported reduced braking forces (improved progression of the center of pressure under the foot), smoother gait and reduced perception of having to “climb over the prosthetic limb” by the patients. one study demonstrated reduced interface pressures between the socket and residual limb while walking on level and uneven terrain and ascending and descending slopes and stairs. one study with a passive mp controlled prosthetic foot also demonstrated significantly improved toe clearance during over-ground walking, reducing the likelihood of tripping over an unseen obstacle of 0.5 cm height from 1/166 steps with an esar foot to 1/3,169 steps with the mp foot. studies also found a reduction of metabolic energy consumption on level ground and a reduction in perceived energy demand for walking up slopes. one study found some improvements but also some deteriorations in biomechanical parameters during slope ambulation. another study demonstrated that it was easier with a mp controlled than with a non-mp controlled hydraulic ankle to control the walking speed while descending a 5° slope. one study with a mp controlled foot with instant terrain adaption and a dorsiflexion stop found that it was more physiologic to stand on a 10° incline and decline with this foot than with other mp controlled feet with only gradual terrain adaption and no dorsiflexion stop. one study found some improvements in biomechanical parameters while ascending and descending stairs. finally, one study also demonstrated significantly reduced interface stress between the socket and the residual limb when using a mp controlled foot as compared to a standard esar foot on varying terrains. studies with a mp controlled powered ankle-foot component found that subjects able to walk with at least 1.2 m/s with their regular esar foot have a good chance to further increase their self-selected walking speed to the level of able-bodied individuals. at higher walking speeds of 1.5 to 1.75 m/s, use of a powered foot may result in a significant 15-20% reduction of sound knee loading, which may have the potential to reduce incidence rates of sound knee osteoarthritis related to long-term prosthesis use. studies also found improved stability while walking on level ground and slopes. there is conflicting evidence on the reduction in metabolic energy consumption during over ground walking: one study showed a significant decrease in energy expenditure, whereas another study could only confirm that for subjects with mfcl-4 mobility. finally, studies reported significantly improved pushoff and walking speed on uneven terrain and normalized ankle power generation and increased plantarflexion during stair ascend. discussion a total of 38 publications on the benefits of prosthetic feet with non-mp hydraulic ankles/dorsiflexion https://doi.org/10.33137/cpoj.v1i1.30450 kannenberg a. evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation: a mini literature review. canadian prosthetics & orthotics journal, volume 1, issue 1, no. 6, 2018, doi: https://doi.org/10.33137/cpoj.v1i1.30450 3 open access evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation volume 1, issue 1, article no. 6, september 2018 feature, passive or powered mp controlled ankles was reviewed. most of the studies had been conducted in gait labs and focused on biomechanical parameters of gait. clinically, the most relevant finding was that non-mp and passive mp controlled ankles may have the potential to increase toe clearance and, thus, reduce the risk of tripping. however, it remains to be studied if that feature also results in reduced falls in the freeliving environment. improved passive ankle motion may result in reduced braking forces, increased selfselected walking speed, and reduced interface pressures between the residual limb and the socket on varying terrains. passive mp controlled feet may also improve the ability to navigate slopes and stairs. powered feet may enable high-functioning individuals with transtibial amputation to further increase their selfselected walking speed to the level of able-bodied subjects while significantly reducing sound knee loading at higher walking speeds. some subjects may also benefit from using a powered ankle-foot component by reducing metabolic energy consumption at faster walking speeds. however, none of studies reported any criteria for identifying patient groups who are more likely to benefit from either type of advanced foot technology than others. thus, matching the right patient with the individually best advanced prosthetic ankle-foot mechanism remains a difficult challenge to clinicians. conclusion prosthetic feet with non-mp or passive mp controlled hydraulic ankles/dorsiflexion feature may be considered for transtibial amputees with compromised toe clearance and tendency to trip. these feet may also be considered for patients who experience increased residual stress while negotiating uneven terrain, slopes and stairs. powered prosthetic feet may be considered for highfunctioning individuals with transtibial amputations who want to further increase their walking capabilities and reduce their long-term risk of developing sound knee osteoarthritis. references 1. hofstad cj, van der linde h, van limbeek j, postema k. prescription of prosthetic ankle-foot mechanisms after lower limb amputation. cochrane database of systematic reviews. cochrane database of systematic reviews (online) 4(1):cd003978, doi: 10.1002/14651858.cd003978.pub2. a. references for non-mp feet/ankle with ankle rom and dorsiflexion feature (2-13) 2. heitzmann dww, salami f, deasha dr, block j, putz c, wolf si, alimusaj m. benefits of an increased prosthetic ankle range of motion for individuals with transtibial amputation walking with a new prosthetic foot. gait posture 2018;64:174-180. doi: 10.1016/j.gaitpost.2018.06.022. 3. childers lw, takahashi kz. increasing foot energy return affects whole-body mechanics during walking on level ground and slopes. nature scient reports 2018;8:5354. doi:10.10138/s441598-0118-23705-8. 4. bai x, ewins d, crocombe ad, wei x. kinematic and biomimetic assessment of a hydraulic ankle/foot in level ground and camber walking. plos one. doi:10.1371/journal.pone.0180836 july 13, 2017. 5. koehler-mcnicholas sr, nickel ea, medvec j, barrons k, mion s, hansen ah. the influence of a hydraulic prosthetic ankle on residual limb loading during sloped walking. plos one. doi:10.1371/journal.pone.0173423 march 9, 2017. 6. moore r. patient evaluation of a novel prosthetic foot with hydraulic ankle aimed at persons with amputation with lower activity levels. j prosthet orthot. 2017;29(1):44-47. doi: 10.1097/jpo. 0000000000000120. 7. moore r. effect on stance phase timing asymmetry in individuals with amputation using hydraulic ankle units. j prosthet orthot. 2016;28(1):44-48. doi: 10.1097/jpo.0000000000000083. 8. de asha ar, munjal r, kulkarni j, buckley jg. impact on the biomechanics of overground gait using an ‘echelon‘ hydraulic ankle-foot device in unilateral trans-tibial and trans-femoral amputees. clin biomech. 2014; 29: 728-734. doi.org/10.1016/j.clinbiomech.2014.06.009. 9. johnson l, de asha ar, munjal r, kulkarni j, buckley jg. toe clearance when walking in people with unilateral amputation: effects of passive hydraulic ankle. j rehabil res dev. 2014; 51(3): 429-438. doi: 10.1682/jrrd.2013.05.0126. 10. de asha ar, johnson l, munjal r, kulkarni j, buckley jg. attenuation of centre-of-pressure trajectory fluctuations under the prosthetic foot when using an articulating hydraulic ankle attachment compared to fixed https://doi.org/10.33137/cpoj.v1i1.30450 kannenberg a. evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation: a mini literature review. canadian prosthetics & orthotics journal, volume 1, issue 1, no. 6, 2018, doi: https://doi.org/10.33137/cpoj.v1i1.30450 4 open access evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation volume 1, issue 1, article no. 6, september 2018 attachment. clin biomech. 2013; 28:218-224. doi:10.1016/j.clinbiomech.2012.11.013. 11. de asha ar, munjal r, kulkarni j, buckley jg. walking speed related joint kinetic alterations in trans-tibial amputees: impact of hydraulic ‘ankle‘ damping. j neuroeng rehabil. 2013; 10: 107-121. doi.org/10.1186/1743-0003-10-107. 12. sedki i, moore r. patient evaluation of the echelon foot using the seattle prosthesis evaluation questionnaire. prosthet orthot int. 2013; 37: 250-254, doi: 10.1177/0309364612458448. 13. portnoy s, kristal a, gefen a, siev-ner i. outdoor dynamic subject-specific evaluation of internal stresses in the residual limb: hydraulic energy-stored prosthetic foot compared to conventional energy-stored feet. gait posture. 2012; 35: 121-125. doi: 10.1016/j.gaitpost.2011.08.021. b. references for passive mp-controlled feet/ankle (14-29) 14. schmalz t, altenburg b, ernst m, bellmann m, rosenbaum d. o 010 – ramp walking with abruptly changing inclines: motion pattern of tt amputees fitted with a microprocessor-controlled and a conventional prosthetic foot. gait posture. 2018. doi: 10.1016/j.gaitpost.2018.06.019. 15. ernst m, altenburg b, bellmann m, schmalz t. standing on slopes – how current microprocessorcontrolled prosthetic feet support transtibial and transfemoral amputees in everyday tasks. j neuroengin rehabil. 2017; 16;14(1):117. doi: 10.1186/s12984-0170322-2. 16. hahn a, sreckovic i, reiter s, mileusnic m. fist results concerning the safety, walking and satisfaction with an innovative, microprocessor-controlled four axes prosthetic foot. prosthet orthot int. 2018; 42(3):350-356. doi: 10.1177/0309364617747976. 17. alexander n, strutzenberger g, kroell j, barnett ct, schwameder h. joint moments during downhill and uphill walking of a person with transfemoral amputation with a hydraulic articulating and a rigid prosthetic ankle – a case study. j prosthet orthot. 2018;30:46-54. doi:10.1097/jpo.0000000000000171. 18. struchkov v, buckley jg. biomechanics of ramp descent in unilateral trans-tibial amputees: comparison of a microprocessor-controlled foot with conventional anklefoot mechanisms. clin biomech. 2016;32:164-170. doi:10.1016/j.clinbiomech.2015. 11.015. 19. rosenblatt nj, bauer a, rotter d, grabiner md. active dorsiflexing prostheses may reduce trip-related fall risk in people with transtibial amputation. j rehabil res dev. 2014; 51(8): 1229-1242. doi: 10.1682/jrrd.2014.01.0031. 20. darter bj, wilken jm. energetic consequences of using a prosthesis with adaptive ankle motion during slope walking in persons with a transtibial amputation. prosthet orthot int. 2014; 38(1):5-11. doi: 10.1177/0309364613481489. 21. agrawal v, gailey r, o´toole c, gaunard i, finnieston a, tolchin r. comparison of four different categories of prosthetic feet during ramp ambulation in unilateral transtibial amputees. prosthet orthot int. 2015;39(5):3809. doi: 10.1177/0309364614536762. 22. agrawal v, gailey r, o´toole c, gaunard i, finnieston a. influence of gait training and prosthetic foot category on external work symmetry during unilateral transtibial gait. prosthet orthot int. 2013; 37(5): 396-403. doi: 10.1177/0309364612473501. 23. agrawal v, gailey r, o´toole c, gaunard i, finnieston a. comparison between microprocessor-controlled ankle/foot and conventional prosthetic feet during stair negotiation in people with unilateral transtibial amputation. j rehabil res dev. 2013; 50(7): 941-950. doi: 10.1682/jrrd.2012.05.0093. 24. delussu as, brunelli s, paradisi f, iosa m, pellegrini r, zenardi d, traballesi m. asessment of the effects of carbon fiber and bionic foot during overground and treadmill walking in transtibial amputees. gait posture. 2013; 38: 876-882. doi: 10.1016/j.gaitpost.2013.04.009. 25. gailey rs, gaunard i, agrawal v, finnieston a, o´toole c, tolchin r: application of self-report and performance-based outcome measures to determine functional differences between four categories of prosthetic feet. j rehabil res dev. 2012;49(4):597-612. 26. fradet l, alimusaj m, braatz f, wolf si. biomechanical analysis of ramp ambulation of transtibial amputees with an adaptive ankle system. gait posture. 2010; 32: 191198. doi: 10.1016/j.gaitpost.2010.04.011. 27. agrawal v, gailey r, o´toole c, gaunard i, dowell t. symmetry in external work (sew): a novel method of quantifiying gait differences between prosthetic feet. prosthet orthot int. 2009; 33(2): 148-156. doi: 10.1080/03093640902777254. 28. alimusaj m, fradet l, braatz f, gerner hj, wolf sj. kinematics and kinetics with an adaptive ankle foot system during stair ambulation of transtibial amputees. gait https://doi.org/10.33137/cpoj.v1i1.30450 kannenberg a. evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation: a mini literature review. canadian prosthetics & orthotics journal, volume 1, issue 1, no. 6, 2018, doi: https://doi.org/10.33137/cpoj.v1i1.30450 5 open access evidence on prosthetic feet with active dorsiflexion feature, passive microprocessor control and active ankle power generation volume 1, issue 1, article no. 6, september 2018 posture. 2009; 30: 356-363. doi: 10.1016/j.gaitpost.2009.06.009. 29. wolf si, alimusaj m, fradet l, siegel j, braatz f. pressure characteristics at the stump/socket interface in transtibial amputees using an adaptive prosthetic foot. gait posture. 2009; 24: 860-865. doi: 10.1016/j.clinbiomech.2009.08.007. c. references for powered feet/ankle (30-46) 30. gardinier es, kelly bm, wensmen j, gates dh. a controlled clinical trial of a clinically-tuned powered ankle prosthesis in people with transtibial amputation. clin rehabil. 2018; 32(3):319-329. doi: 10.1177/0269215517723054. 31. pickle nt, grabowski am, jeffers jr, silverman ak. the functional roles of muscles, passive prostheses, and powered prostheses during sloped walking in people with transtibial amputation. j biomech eng. 2017;1;139(11). doi: 10.1115/1.4037938. 32. rabago ca, aldridge whitehead j, wilken jm. evaluation of a powered ankle-foot prosthesis during slope ascent gait. plos one. 15;11(12):e0166815. doi: 10.1371/journal.pone.0166815. ecollection 2016. 33. pickle nt, wilken jm, aldridge whitehead jm, silverman ak. whole-body angular momentum during sloped walking using passive and powered lower-limb prostheses. j biomech. 2016 3;49(14):3397-3406. doi:10.1016/j.jbiomech.2016.09.010. 34. russell esposito e, aldridge jm, wilken jm. step-tostep transition work during level and inclined walking using passive and powered ankle-foot prostheses. prosthet orthot int. 2016;40(3):311-9. doi: 10.1177/0309364614564021. 35. takahashi kz, horne jr, stanhope sj. comparison of mechanical energy profiles of passive and active belowknee prostheses: a case study. prosthet orthot int. 2015;39(2):150-6. doi: 10.1177/0309364613513298. 36. d’andrea s, wilhelm n, silverman ak, grabowksi am. does use of a powered ankle-foot prosthesis restore whole-body angular momentum during walking at different speeds? clin orthoped rel res. 2014;472:3044-3054. doi 10.1007/s.11999-014-3647-1. 37. russell esposito e, wilken jm. biomechanical risk factors for knee osteoarthritis when using passive and powered ankle-foot prostheses. clin biomech. 2014;29(10):1186-92. doi:10.1016/j.clinbiomech.2014.09.005. 38. grabowski am, d’andrea s. effects of a powered ankle-foot prosthesis on kinetic loading of the unaffected leg during level-ground walking. j neuroeng rehabil. 2013; 7;10:49. doi: 10.1186/1743-0003-10-49. 39. gates dh, aldridge jm, wilken jm. kinematic comparison of walking on uneven ground using powered and unpowered prostheses. clin biomech. 2013;28(4):467-72. doi:10.1016/j.clinbiomech.2013.03.005. 40. hill d, herr h. effects of a powered ankle-foot prosthesis on kinetic loading of the contralateral limb: a case series. ieee int conf rehabil robot. 2013 ;2013:6650375. doi: 10.1109/icorr.2013.6650375. 41. herr hm, grabowski am. bionic ankle-foot prosthesis normalizes walking gait in for persons with leg amputations. proc r sco b 2012; 7;279(1728):457-64. doi: 10.1098/rspb.2011.1194. 42. ferris ae, aldridge jm, rabago c, wilken jm. evaluation of a powered ankle-foot system during walking. arch phys med rehabil. 2012 ;93(11):1911-8. doi: 10.1016/j.apmr.2012.06.009. 43. aldridge jm, sturdy jt, wilken jm. stair ascent kinematics and kinetics with a powered lower leg system following transtibial amputation. gait posture. 2012;36:291-295. doi 10116/j.gaitpost.2012.03.013. 44. mancinella c, patritti bl, tropea p, greenwald rm, casler r, herr h, bonato p. comparing a passive-elastic and a powered prosthesis in transtibial amputees. conf proc ieee eng med biol soc. 2011;2011:8255-8. doi: 10.1109/iembs.2011. 6092035. 45. au sk, weber j, herr h. powered ankle-foot prosthesis improves walking metabolic economy. ieee transactions robotics. 2009;25(1):51-66. doi: 10.1109/tro.2008.2008747. 46. au sk, herr h, weber j, martinez-villalpando ec. powered ankle-foot prosthesis for the improvement of amputee ambulation. conf proc ieee eng med biol soc. 2007;2007:3020-6. disclosure dr. andreas kannenberg is a full-time employee of otto bock healthcare lp, austin, tx. https://doi.org/10.33137/cpoj.v1i1.30450 stech n, mcgrath m, laszczak p, kercher a, zahedi s, moser d. biomechanical analysis of different prosthetic technologies for trans-femoral amputees during slope descent. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32012 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) biomechanical analysis of different prosthetic technologies for trans-femoral amputees during slope descent nadine stech*1, michael mcgrath1, piotr laszczak1, alan kercher2, saeed zahedi1, david moser1 1endolite technology centre, basingstoke, uk 2endolite north america, miamisburg, oh, usa * email: nadine.stech@blatchford.co.uk doi: https://doi.org/10.33137/cpoj.v1i2.32012 introduction lower limb amputees have different biomechanics to able-bodied people when walking on slopes1,2, often struggling to negotiate different gradients safely. loss of proprioception and muscular control contributes to this issue, which is a particular problem for trans-femoral amputees, where both ankle and knee joints are absent. studies have shown that prosthetic technologies can have benefits for slope negotiation. the aim of this study was to isolate the specific effects of different trans-femoral prosthetic technologies, by applying each additional mechanism incrementally. methods four prosthetic conditions were tested in a randomised order: (1) a rigid ankle, esr foot (esprit, endolite – ra) (2) a hydraulic ankle-foot with constant resistances to pf and df (ha) (3) a microprocessor-controlled hydraulic anklefoot (elan, endolite – mpf) that varied resistances to pf and df (4) a microprocessor-controlled, integrated limb system (linx, endolite – mpl) that both varied resistances to pf and df at the ‘ankle’ and applied a yielding support at the prosthetic knee during step-to-step transition. for the cohort of trans-femoral amputees, a gait analysis motion capture system and a slope-integrated force plate were used to measure kinematic and kinetic parameters as the participant walked down a 5° slope at their comfortable walking speed. a 5° slope was selected as this aligns with the ada regulations regarding disability access ramps – a common real-life environmental barrier. results each incremental change in technology showed distinct biomechanical effects on the gait of the user. the transition from ra to ha showed a better foot compliance with the ground, reducing the time taken to achieve foot flat and a smoother progression of the shank segment with ha. with the mpf, the transition from df to pf ‘ankle’ moment occurred earlier, implying a smaller resistance to pf movement, further enhancing ground compliance, and a greater resistance to df movement, implying a ‘braking’ action to control shank rotation. further to just the mpf, the mpl introduced yielding at the knee during late stance phase, which was evident in the kinematic and kinetic knee joint curves. the rate of flexion in late stance was reduced, absorbing less joint power, allowing for a controlled transition of body mass from the prosthetic limb to the sound limb. figure 1: (top) ankle moment curves showing the effect of mpf (blue) compared to ha (black) and (bottom) knee power curves showing the effect of mpl with knee yielding (green) compared to mpf only (blue). mailto:nadine.stech@blatchford.co.uk https://doi.org/10.33137/cpoj.v1i2.32012 stech n, mcgrath m, laszczak p, kercher a, zahedi s, moser d. biomechanical analysis of different prosthetic technologies for trans-femoral amputees during slope descent. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32012 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) conclusion this study isolated the individual effects of incremental increases in technologies design to aid ramp negotiation for trans-femoral amputees. these technologies have been shown to provide greater bodyweight support by replicating natural muscular control at the prosthetic ‘ankle’ and knee joints. significance advanced prosthetic technology can provide benefits for trans-femoral amputees when negotiating slopes. understanding these effects helps to make informed prescriptions. references 1.vickers et al. elderly unilateral transtibial amputee gait on an inclined walkway: a biomechanical analysis. gait posture. 2008;27(3):518–529. doi:10.1016/j.gaitpost.2007.06.008 2.vrieling et al. uphill and downhill walking in unilateral lower limb amputees. gait posture. 2008;28(2):235–242. doi:10.1016/j.gaitpost.2007.12.006 3. struchkov v, buckley jg. biomechanics of ramp descent in unilateral trans-tibial amputees: comparison of a microprocessor controlled foot with conventional ankle-foot mechanisms. clin biomech. 2016;32:164–170. doi:10.1016/j.clinbiomech.2015.11.015 4.highsmith et al. ramp descent performance with the c-leg and interrater reliability of the hill assessment index. prosthet orthot int. 2013;37(5):362-8. doi: 10.1177/0309364612470482 disclosure the authors are employees of endolite north america or blatchford (the parent company of endolite north america); the manufacturer of the prosthetic devices used in this study. https://doi.org/10.1016/j.gaitpost.2007.06.008 https://doi.org/10.1016/j.gaitpost.2007.12.006 https://doi.org/10.1016/j.clinbiomech.2015.11.015 https://doi.org/10.1177/0309364612470482 mayo a.l, cimino s.r, hitzig s.l. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.1. https://doi.org/10.33137/cpoj.v2i1.31950 issn: 2561-987x volume 2, issue 1 2019 (online) r e s e a r c h a r t i c l e all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com mayo a.l, cimino s.r, hitzig s.l. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.1. https://doi.org/10.33137/cpoj.v2i1.31950 1 open access dysvascular lower extremity amputation volume 2, issue 1, article no.1, february 2019 https://jps.library.utoronto.ca/index.php/cpoj/index research article a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation mayo a.l.1,2 *, cimino s.r.3, hitzig s.l.3,4,5 1 st. john’s rehab, sunnybrook health sciences centre, toronto, canada. 2 faculty of medicine, university of toronto, toronto, canada. 3 st. john’s rehab research program, evaluative clinical sciences, sunnybrook research institute, toronto, canada. 4 rehabilitation sciences institute, faculty of medicine, university of toronto, toronto, canada. 5 department of occupational science & occupational therapy, faculty of medicine, university of toronto, toronto, canada. abstract background: the majority of lower limb amputations (lla) in canada are dysvascular due to complications of diabetes and/or vascular disease. traditionally dysvascular amputations have occurred in the elderly. with younger onset of adult diabetes, amputations are now occurring in non-geriatric populations. an understanding of younger patients with dysvascular lla is needed to determine their risk factors, and unique health and psychosocial challenges. objectives: to obtain a depiction of the key demographic and impairment characteristics of adults 65 years and younger with dysvascular lla undergoing inpatient rehabilitation. methodology: a retrospective chart review was completed on inpatient adult amputation rehabilitation patients over a five year period. data extracted included socio-demographics, functional independence measure (fim) scores, comorbidities, and discharge outcomes. findings: one hundred and forty-three patients who were 65 years and younger were included, which represented almost a quarter of all admissions. most patients were male (79%) with an average age of 55 years old (sd=8). the majority (72%) were unemployed. the mean number of co-morbidities was 5.2 (sd=8.2). individuals discharged home (n=122) had higher (p<0.05) fim scores than those readmitted to acute care or discharged to long-term care (n=20). conclusions: similar to the literature on older dysvascular lla patients, our study found high rates of disability and co-morbidities in younger patients with dysvascular lla, which might impact their ability to work. given these challenges, better amputation prevention strategies and targeted rehabilitation programming for this population are needed. citation mayo a.l, cimino s.r, hitzig s.l. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.1. https://doi.org/10.33137/cpoj.v 2i1.31950 keywords dysvascular, limb loss, amputation, outcomes, lower extremity, sociodemographics, inpatient rehabilitation. *corresponding author amanda l. mayo, md, mhsc, frcpc 1) physiatrist: st. john’s rehab, 285 cummer avenue, toronto, on, canada m2m 2g1; 2) assistant professor, faculty of medicine, university of toronto, toronto, canada. tel: 416.226.6780 email: amanda.mayo@sunnybrook.ca doi: https://doi.org/10.33137/cpoj.v2i1.31950 article info received: december 2, 2018 accepted: february 21, 2019 published: february 27, 2019 https://doi.org/10.33137/cpoj.v2i1.31950 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v2i1.31950 https://doi.org/10.33137/cpoj.v2i1.31950 https://doi.org/10.33137/cpoj.v2i1.31950 mayo a.l, cimino s.r, hitzig s.l. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.1. https://doi.org/10.33137/cpoj.v2i1.31950 2 open access dysvascular lower extremity amputation volume 2, issue 1, article no.1, february 2019 https://jps.library.utoronto.ca/index.php/cpoj/index introduction major lower limb amputation (lla) is a life-altering event that can negatively affect an individual’s physical function, emotional well-being and quality of life.1 in north america, most lla are dysvascular in etiology, resulting from the complications of diabetes mellitus, and/or vascular disease.2-4 a study on the total number of amputations done in canada reported there were 5,342 persons (mean age 67 (sd=13) years) who underwent lla between 2006 and 2009, with over 80% of the lla being dysvascular in nature.3 imam and colleagues2 also examined incidence of minor and major lower extremity amputation in canada between 2006 and 2012 and found 44,430 amputations were done in mostly male (69%) diabetic (65%) patients with a mean age of 65.7 (sd=16.6) years. the most common level of amputation was transtibial. imam et al. also reported the incidence of canadian diabetic lla increased by 13% from 2006-2012.2 secondary complications associated with diabetes, such as renal failure, visual impairment, neuropathy, and cardiovascular disease can impact functional outcomes after amputation,5-8 as can depression, anxiety, and pain.9 common health conditions impacting function of older adults include respiratory disease10 (e.g., chronic obstructive pulmonary disease),11,12 end-stage renal failure,13 stroke12 and cognitive impairment due to dementia.11 it has been reported that older adults with dysvascular lla can have on average 6.5 co-morbidities.14 the dysvascular lla population has a poor survival rate, with a 2-year mortality rate of 16%-56%,15 and a 5-year survival rate of 23%-45%.14 these patterns of mortality have not changed in 40 years.16 the worldwide incidence of diabetes is increasing, and is closely linked to the rising rates of adult obesity, sedentary lifestyle, and poor dietary habits.17 traditionally, dysvascular amputation has been associated with older age (over 65 years old).23 in canada, an increased incidence of diabetes has been found to be the most significant in adults aged less than 50.18 maturity onset diabetes of the young (mody) has been associated with a more aggressive disease course and higher risk of end stage complications.19 a recent study by geiss and colleagues20 found an increase in the rates of total, major, and minor amputations in the united states, which were most pronounced in young (age 18–44 years) and middle-aged (age 45–64 years) adults. they also found that men also contributed to this increase in amputations due to diabetes while the rates for women and older adults have plateaued after having decreased in recent years.20 adults who are younger than 65 years old with dysvascular amputations present unique challenges to healthcare and rehabilitation teams as these patients are in their employment years and may have complex family stressors.21,22 to date, the majority of dysvascular lla research has focused on older adults, and there is no existing canadian data on lla in younger adults. as a population of younger dysvascular lla patients emerges, a better understanding of their characteristics is needed. doing so will provide insight on whether their health can be modified to prevent amputation or promote better lla long-term outcomes (e.g., prevention of a second amputation; decreasing early mortality, return to work, etc.). during the rehabilitation process, a large focus on the physical health of the patients is often taken and may not adequately address or acknowledge their psychosocial functioning.23 there is evidence that addressing mental and social issues within the lla rehabilitation process can improve outcomes.24 to help address gaps in knowledge of the younger adult dysvascular lla patient population (65 years old and younger), the purpose of this study was to describe the key demographic and impairment characteristics of this understudied population. this data will help advance clinical knowledge to help identify younger dysvascular patients at risk of amputation and foster better approaches to rehabilitation and secondary prevention care. methodology a retrospective chart review was conducted on patients who received inpatient amputation rehabilitation at an urban rehabilitation hospital, sunnybrook health sciences centre’s st. john’s rehab (sjr), for a major dysvascular lla. sjr provides extensive assessment, treatment and resources for health promotion to patients recovering from amputation. the large interprofessional team consists of physiatrists, hospitalist physician, prosthetists, psychiatrists, physiotherapists, occupational therapists, a social worker, a speech https://doi.org/10.33137/cpoj.v2i1.31950 https://jps.library.utoronto.ca/index.php/cpoj/index mayo a.l, cimino s.r, hitzig s.l. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.1. https://doi.org/10.33137/cpoj.v2i1.31950 3 open access dysvascular lower extremity amputation volume 2, issue 1, article no.1, february 2019 https://jps.library.utoronto.ca/index.php/cpoj/index language pathologist and a dietician. sjr has approximately 125 new inpatient amputation admissions per year, and has a large outpatient services department to provide ongoing rehabilitation and support post-discharge from inpatient rehabilitation. data from charts from discharged inpatients over a five-year period (between october 31, 2012 and october 31, 2017) were extracted for review via the hospital’s decision support information management team. the information obtained included: sociodemographics, impairment characteristics; admission and discharge functional independence measure [fim] score,25 co-morbidities and rehabilitation and/or discharge outcomes. all the data utilized for analysis is information typically collected from patients who participate in the rehabilitation program at sjr. study approval was obtained by the research ethics board at the sunnybrook health sciences centre. socio-demographic variables were comprised of sex, age at admission, and location of residence (urban or rural) as coded by canada post.26 amputation and impairment characteristics consisted of date of amputation, acute care setting location, dysvascular cause of amputation and characteristics of amputation (e.g. unilateral or bilateral and level of major lla). a list of common comorbidities and secondary health conditions typically seen in the dysvascular lla population (e.g. diabetes, hypertension, dyslipidemia, smoking, previous amputation, etc.) were recorded at discharge from rehabilitation and prevalence of each co-morbidity/condition was determined. a total number of co-morbidities and secondary health conditions score was created by summing each comorbidity/condition. in order to determine pain and pain management, the presence or absence of pain was recorded as were pain severity on admission and discharge. the pain severity score is a subjective patient reported rating used at sjr. it is a pain scale that ranges from 0 to 3 (0=no pain; 1=mild pain; 2=moderate pain; and 3=severe pain). the fim is a basic indicator of patient disability. it is used to assess the changes in the functional ability of a patient during an episode of hospital rehabilitation care along two dimensions: motor (13 items) and cognitive (5 items).27 fim scores range from 18 to 126, with higher scores indicating higher levels of function. the fim was designed to be used across various disability groups and has been used in the lla population.28-30 a study examining the psychometric properties of the fim across 20 impairment categories (including lla) found the fim sub-scales exceeded minimum criteria for item internal consistency in 96.9% of tests and item discriminant validity in 100% of tests.31 further, the reliability coefficients ranged between 0.86 to 0.97 across each impairment group for both subscales.31 an improvement of 8 points on the fim has been deemed to be clinically meaningful for patients undergoing specialized rehabilitation for lla.32 for the present study, the fim was collected upon admission to rehabilitation as well as on discharge. outcomes related to rehabilitation and discharge included the date the patient was ready for rehabilitation, date of inpatient admission, date of inpatient discharge, time to rehabilitation and active length of stay (los). employment status was collected prior to admission as well as on discharge. it was separated into two categories employed (full-time, part-time, adjusted/modified, unpaid employment or student) and unemployed (retired, unemployed, on disability). living situation prior to admission and discharge destination was also determined. discharge destination included return to home, retirement home, hospital transfer (to acute care for medical instability), residential care facility, or long-term care home. participants adult patients from age 18 to 65 admitted to sjr for inpatient amputation rehabilitation following a major dysvascular lla (transfemoral, knee disarticulation, transtibial, or ankle disarticulation level) between october 31, 2012 and october 31, 2017 were eligible for inclusion. patients with non-dysvascular amputations from trauma, cancer, burns, or nondiabetic related infection were excluded. minor amputations (partial feet and toe amputations) were excluded as were patients who underwent an upper extremity amputation. data analysis frequencies and descriptive statistics were calculated for the data. to compare within group differences (e.g., rural vs. urban lla patients) on certain outcomes (e.g., fim change score; pain intensity), chi-square (or fisher’s exact test) and https://doi.org/10.33137/cpoj.v2i1.31950 https://jps.library.utoronto.ca/index.php/cpoj/index mayo a.l, cimino s.r, hitzig s.l. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.1. https://doi.org/10.33137/cpoj.v2i1.31950 4 open access dysvascular lower extremity amputation volume 2, issue 1, article no.1, february 2019 https://jps.library.utoronto.ca/index.php/cpoj/index paired t-tests were utilized. as well, correlations were used to examine relationships between variables. results from october 31, 2012 to october 31, 2017; a total of 643 patients with lla were admitted to sjr for inpatient amputation rehabilitation. of those, fourhundred and ninety-six did not meet the inclusion criteria due to either being older than 65 years of age or because they had a non-dysvascular etiology (e.g., trauma), an upper-extremity amputation or minor lla. hence, one-hundred and forty-three patients were included for study chart review (22%). it should be noted that four patients were re-admitted for inpatient rehabilitation during this time period but there was no change in their level of amputation across both hospital admissions. the sociodemographic and impairment characteristics are presented in table 1. the average age at amputation was 55 (sd=8) years, with an age range of 21 to 65 years old. twenty percent of patients were younger than 50, 47% were aged 50 to 59 years, and the remaining 33% were aged 60 to 65 years. the vast majority of patient amputations (n=138, 96%) were due to chronic complications of diabetes and/or vascular disease including infections, ulcers, chronic ischemia and gangrene. only five patients had acute vascular events leading to amputation. four of the five acute patients had acute emboli/thrombosis leading to lla. the other acute patient was in their thirties and had a lla resulting from dissection of a vascular aneurysm. eighteen patients had a previous amputation. of those with a previous amputation, the majority (n=12, 67%) were between the ages of 50 and 59. no details were available if the previous amputations were minor or major in nature. figure 1 highlights the top ten most common co-morbidities/secondary health conditions found in our cohort. on average, patients had five comorbidities/secondary health conditions (sd=2.4), with 27.2% having at least 7 co-morbidities/ conditions (see figure 2). other co-morbidities included obesity (n=21), and respiratory disease (n=15). fourteen patients had documented psychiatric conditions, such as bipolar disorder (n=4), schizophrenia (n=1), adjustment disorder (n=2) and drug addiction (n=7). 8.4% of patients had a clinical diagnosis of depression and 2.8% were diagnosed with an anxiety disorder. when examining relationships between key demographic and impairment characteristics with co-morbidities/ secondary health conditions, patients 50 years of age and older (n=115) were more likely to have atherosclerosis (47%; p<0.05) than those who were younger than 50 years of age (n=28), with only 21% having the condition. as well, patients 50 years of age and older were more likely to have heart disease (30%; p<0.05) than those who were less than 50 years of age (7%). conversely, patients younger than 50 years of age were more likely to have osteomyelitis leading to amputation (14%; p<0.01) than the older cohort (1%). notably, the proportion of those from rural settings (n=11) were more likely to have a pressure ulcer (55%; p<0.05) than those from urban settings (n=132; 28%). table1: sample demographic and impairment characteristics (n=147). variable frequency (%) sex • male 113 (79.0%) • female 30 (21.0%) language • english speaking 140 (97.9%) • non-english speaking 3 (2.1%) level of amputation • above knee 30 (21.0%) • below knee 109 (76.2%) • bilateral above knee 1 (0.7%) • bilateral below knee 2 (1.4%) • bilateral (one leg ak; one leg bk) 1 (0.7%) pre-rehab admission living situation • home 143 (100%) rehab discharge living situationa • home 122 (85.3%) • acute care 15 (10.5%) • long-term care 5 (3.5%) geographic region • urban 132 (92.3%) • rural 11 (7.7%) employment statusa • employed at time of rehab admission 40 (28.0%) • unemployed at time of rehab admission 102 (72.1%) • employed at time of rehab dischargeb 16 (11.2%) • unemployed at time of rehab discharge 109 (76.2%) a data missing for one participant; b data missing for 18 participants; https://doi.org/10.33137/cpoj.v2i1.31950 https://jps.library.utoronto.ca/index.php/cpoj/index mayo a.l, cimino s.r, hitzig s.l. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.1. https://doi.org/10.33137/cpoj.v2i1.31950 5 open access dysvascular lower extremity amputation volume 2, issue 1, article no.1, february 2019 https://jps.library.utoronto.ca/index.php/cpoj/index figure 1: top 10 most common co-morbidities/secondary health conditions. figure 2: total number of co-morbidities. note: maximum number of co-morbidities was 13. in regards to pain, 122 persons had completed pain rating scores at both admission and discharge, with 86.1% having pain on admission to rehabilitation and 64.8% had pain still present on discharge. further, for those with both a pain admission and pain discharge severity score (n=122), patients with mild pain had similar pain scores, but the pain intensity scores decreased for the moderate and severe groups (figure 3). figure 3: frequency of pain severity ratings at admission and discharge. (n=122 patients) in terms of los, the sample was admitted to inpatient rehabilitation on for average 35.9 (sd=15) days, with a mean fim admission score of 86.9 (sd=11.1) and fim discharge score of 107.6 (sd=8.5). fim discharge scores were not completed for 13 persons. when examining various sociodemographic factors on outcomes, the proportion of women (n=3) who had undergone a bilateral amputation was higher than the proportion of men (n=1; p<0.05). there were no differences in fim scores between men and women. men were significantly older (m=56.0; sd=7.5; t[141]=2.3, p<0.05) than women (m=52.2; sd=10.0). older age was associated with a lower fim discharge score (r=-0.21, p<0.05). having more co-morbidities/secondary health conditions was associated with a lower fim admission score (r=-0.20, p<0.05), and lower fim discharge score (r=-0.24, p<0.01). similarly, having more co-morbidities/conditions was associated with a longer los (r=-0.19, p<0.05). those who were discharged to home (n=122) had higher fim admission scores (m=87.9; sd=10.3) than those who were discharged to an acute care or long-term care setting (n=20; m=80.8; sd=14.0; t[22.5]=2.2, p<0.05). discussion the present study is the first canadian study, to our knowledge, to examine the specific characteristics of a younger cohort of adult patients with a dysvascular lla. almost a quarter (22%) of our lla admissions over a five year period were 65 years old and younger, which might be representative of the dropping age of onset of adult diabetes in canada.12 it may also reflect the more aggressive nature of mature onset diabetes in the younger population as well as premature atherosclerosis.18,19,33 our findings, along with those of geiss et al.20 who also found an increasing rate of younger adults with diabetes undergoing amputation, illustrates a disturbing trend. younger dysvascular lla patients may have different psychosocial challenges, such as employment and childcare responsibilities, than geriatric patients.21 to maximize return of function and community reintegration post-amputation, rehabilitation programs must address the unique needs of younger dysvascular patients. adding to the complexity is that our younger cohort still had high rates of medical co-morbidities similar to the rates 3 14 30 22 20 15 19 8 6 4 0 8 15 23 30 38 1 2 3 4 5 6 7 8 9 10 + n u m b e r o f p a ti e n ts number of co-morbidities 30 45 3031 32 16 0 13 25 38 50 mild moderate severe n u m b e r o f p a ti e n ts admission discharge 85 82 72 60 46 36 35 31 26 24 0 23 45 68 90 diabetes hypertension anaemia arthersclerosis phantom limb pain other heart disease hypercholesterolemia pressure ulcer renal bowel and bladder problems number of patients https://doi.org/10.33137/cpoj.v2i1.31950 https://jps.library.utoronto.ca/index.php/cpoj/index mayo a.l, cimino s.r, hitzig s.l. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.1. https://doi.org/10.33137/cpoj.v2i1.31950 6 open access dysvascular lower extremity amputation volume 2, issue 1, article no.1, february 2019 https://jps.library.utoronto.ca/index.php/cpoj/index described in the geriatric dysvascular lla population.34,35 long-term outcomes, including mortality, of the younger dysvascular patient has yet to be studied. although rates of depression and anxiety (11%) were relatively low in our cohort, another 10% of our patients had a chronic mental health diagnosis (schizophrenia, bipolar disorder, adjustment disorder, addiction), with four of them having comorbid depression and/or anxiety. thus, over a fifth of the patients had documented significant mental health issues. mental health issues are important to monitor in patients with limb loss since sequelae of mood issues post-amputation include low self-worth, impaired body image36 and high rates of suicidal ideation.37 previous studies have shown that the rates of depression post-amputation can be as high as 60%.38 depression post-lla is associated with lower prosthetic use, higher perceived vulnerability, and lower self-rated overall health.39 the lower rates of depression and anxiety in our inpatient rehabilitation population may be supportive of previous evidence highlighting that depression and anxiety is exacerbated upon discharge to the community.40 future studies should track the longterm psychosocial outcomes of this cohort since depression and anxiety can negatively influence outcomes in a number of domains. despite being in the typical canadian working age range (18-65 years), our cohort had high rates of unemployment (72%) at time of rehab admission, and that increased slightly at discharge (76%). this is consistent with previous findings that diabetic foot ulcers and amputations are associated with high rates of disability and unemployment.41-43 in a recent study of patients with diabetic foot ulcers, only 12% had full-time employment.43 often mobility is limited months prior to dysvascular amputation due to wounds, pain, restricted weight-bearing, and/or offloading casts.44 it is possible that the individuals described in this study may have returned to work after a certain recovery period but there several issues that makes this process challenging. most notably is that return to work after amputation is often limited by lack of accommodations and inaccessible workplaces.42 as well, our cohort had on average five co-morbidities, and a high number of co-morbidities has been shown to be a negative prognosis for employment.42,43 the rates of unemployment in this population is concerning as employment is associated with higher health related quality of life.42 vocational retraining and/or work modifications may be needed for lla patients with labour intensive occupations while those with office jobs or sedentary occupations typically have higher rates of return to work after lla.45 overall, there is a need to ensure better employment opportunities and/or financial supports for the dysvascular lla population. there were significant differences found between male and female lla patients, with men being on average four years older than women, and women being more likely to have bilateral amputations. despite the women in the study being younger, both sexes reached the same average fim score by rehabilitation discharge. our findings suggest that females with diabetes and/or vascular disease have younger onset amputation risk, but further work is needed to explore this given the small number of women (n=30) in our cohort. overall, there is a paucity of literature comparing dysvascular lla between males and females, and there is a need for more research to examine in detail sex and gender differences. in keeping with previous studies, most patients were able to return home post inpatient rehabilitation.45 patients with higher number of co-morbidities had longer rehabilitation stays and were more likely to be discharged back to acute care for medical instability. discharge to long-term care was also associated with higher number of co-morbidities. co-morbidities of chronic heart failure and renal failure/dialysis have poor prognosis for independent living, morbidity and mortality in the dysvascular lla population.46 rehabilitation teams must take into consideration the number of co-morbidities when planning rehabilitation intensity, los, community care needs and discharge destination planning. there are several limitations with the data that should be acknowledged. the data from the charts were extracted via a trained healthcare data analyst from the hospital system. as a result, there are likely some additional data from the charts that would have provided a richer clinical description of the sample, such as details regarding those who had undergone a previous amputation. there were also some instances of missing data, which may have affected some of the results (e.g., missing discharge destination, missing discharge fim scores, etc.). given the noted high rates of mortality in the overall https://doi.org/10.33137/cpoj.v2i1.31950 https://jps.library.utoronto.ca/index.php/cpoj/index mayo a.l, cimino s.r, hitzig s.l. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.1. https://doi.org/10.33137/cpoj.v2i1.31950 7 open access dysvascular lower extremity amputation volume 2, issue 1, article no.1, february 2019 https://jps.library.utoronto.ca/index.php/cpoj/index dysvascular lla population (including those over 65 years old),15 it would have been informative if we were able to collect mortality data. future studies should examine this issue to determine if younger dysvascular lla have the same high rates of mortality as those over age 65. more importantly, future studies should directly examine differences between younger (65 years and younger) and older adults (over 65 years old) across a variety of functional, health and psychosocial domains to better understand their rehabilitation needs. despite the limitations of this dataset, the findings from this study provide some considerations for planning future research and highlight clinical issues for advancing knowledge and care for this population. conclusion this study demonstrated that approximately one quarter of individuals with dysvascular lla admitted to inpatient rehabilitation are 65 years and younger. this younger proportion of the lla population will continue to increase if the age of diabetes onset continues to decrease. a higher number of comorbidities in dysvascular lla is associated with longer rehabilitation los, lower fim scores, and higher care needs on discharge from rehabilitation. rates of unemployment were high in our young dysvascular lla patient cohort. more resources (e.g., education) are needed to prevent lla in this population given the functional, psychological, financial impacts of amputation, and high rates of mortality. rehabilitation programs for lla may need to evolve to incorporate appropriate programming for younger dysvascular patients including return to employment. acknowledgements we would like to thank grace liu, nrs coordinator in clinical informatics at st. john’s rehab and marie disotto-monastero, manager in clinical informatics at st. john’s rehab, for their time in extracting the data. we would also like to thank jorge rios, lab manager at st. john's rehab research program, for his support in preparing the manuscript. declaration of conflicting interests the authors have no conflicts of interest to declare. sources of support funding for this study was provided by the st. john’s rehab research program, sunnybrook research institute. ethical approval study approval was obtained by the research ethics board at the sunnybrook health sciences centre. author contribution • amanda l. mayo, conceived the idea for the project, supported the data analysis, and led the writing of the manuscript. • stephanie r. cimino, managed the data files, supported the writing of the manuscript, and provided insights into the interpretation of the data. • sander l. hitzig, conducted the statistical analyses, and supported the writing of the manuscript. references 1. amtmann d, morgan sj, kim j, hafner bj. healthrelated profiles of people with lower limb loss. arch phys med rehabil. 2015;96(8):1474-83. doi:10.1016/j.apmr. 2015.03.024 2. imam b, miller wc, finlayson hc, eng jj, jarus t. incidence of lower limb amputation in canada. can j public health. 2017;108(4):e374-e80.doi:10.17269/ cjph.108.6093 3. kayssi a, de mestral c, forbes tl, roche-nagle g. a canadian population-based description of the indications for lower-extremity amputations and outcomes. can j surg. 2016;59(2):99-106. doi:10.1503/cjs.013115 4. ziegler-graham k, mackenzie ej, ephraim pl, travison tg, brookmeyer r. 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categories. arch phys med rehabil, 1996. 77(11):1101-8. 32. stineman mg, kwong pl, xie d, kurichi je, ripley dc, brooks dm, et al. prognostic differences for functional recovery after major lower limb amputation: effects of the timing and type of inpatient rehabilitation services in the veterans health administration. pm r. 2010;2(4):232-43. doi:10.1016/j.pmrj.2010.01.012 33. valentine rj, myers si, inman mh, roberts jr, clagett gp. late outcome of amputees with premature atherosclerosis. surgery. 1996;119(5):487-93. doi: https://doi.org/10.1016/s0039-6060(96)80255-8 34. dillingham tr, pezzin le. rehabilitation setting and associated mortality and medical stability among persons with amputations. arch phys med rehabil. 2008;89(6): 1038-45. doi:10.1016/j.apmr.2007.11.034 35. gailey rs, roach ke, applegate eb, cho b, cunniffe b, licht s, et al. the amputee mobility predictor: an instrument to assess determinants of the lower-limb amputee's ability to ambulate. arch phys med rehabil. 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with diabetic foot ulcers. diabetic foot. 2000;3:150-5. 42. journeay ws, pauley t, kowgier m, devlin m. return to work after occupational and non-occupational lower extremity amputation. occup med (lond). 2018;68(7): 43843. doi:10.1093/occmed/kqy091 43. ribu l, hanestad br, moum t, birkeland k, rustoen t. a comparison of the health-related quality of life in patients with diabetic foot ulcers, with a diabetes group and a nondiabetes group from the general population. qual life res. 2007;16(2):179-89. doi:10.1007/s11136-006-0031-y 44. czerniecki jm, turner ap, williams rm, hakimi kn, norvell dc. mobility changes in individuals with dysvascular amputation from the presurgical period to 12 months postamputation. arch phys med rehabil. 2012;93(10):1766-73. doi:10.1016/j.apmr.2012.04.011 45. kayssi a, dilkas s, dance dl, de mestral c, forbes tl, roche-nagle g. rehabilitation trends after lower extremity amputations in canada. pm r. 2017;9(5):494501. doi:10.1016/j.pmrj.2016.09.009 46. henry aj, hevelone nd, hawkins at, watkins mt, belkin m, nguyen ll. factors predicting resource utilization and survival after major amputation. j vasc surg. 2013;57(3):784-90. doi:10.1016/j.jvs.2012.09.035 https://doi.org/10.33137/cpoj.v2i1.31950 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.1016/j.pmrj.2010.01.012 https://doi.org/10.1016/s0039-6060(96)80255-8 https://doi.org/10.1016/j.apmr.2007.11.034 https://doi.org/10.1053/apmr.2002.32309 https://doi.org/10.1053/apmr.2002.32309 https://doi.org/10.1111/dme.12474 https://doi.org/10.1016/j.apmr.2015.04.001 https://doi.org/10.1111/ggi.12016 https://doi.org/10.1046/j.1365-2044.2001.01714.x https://doi.org/10.1093/occmed/kqy091 https://doi.org/10.1007/s11136-006-0031-y https://doi.org/10.1016/j.apmr.2012.04.011 https://doi.org/10.1016/j.pmrj.2016.09.009 https://doi.org/10.1016/j.jvs.2012.09.035 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 research article issn: 2561-987x all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x volume 1, issue 2 2 0 1 8 https://doi.org/10.33137/cpoj.v1i2.31326 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 1 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 research article development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study frossard l1,2,3*, ferrada l4, quincey t4, burkett b3, berg d4 1institute of health and biomedical innovation, queensland university of technology, brisbane, australia. 2school of nursing, midwifery and paramedicine, faculty of science, health, education and engineering, university of the sunshine coast, maroochydore, australia. 3school of allied health sciences, griffith university, gold coast, australia. 4queensland health, queensland artificial limb service, brisbane, australia. *corresponding author adj / professor laurent frossard (phd), orcid: 0000-0002-0248-9589 po box 143, red hill, 4059, qld, australia. phone: +61 (0)413795086; e-mail: laurentfrossard@outlook.com doi: https://doi.org/10.33137/cpoj.v1i2.31326 citation frossard l, ferrada l, quincey t, burkett b, and berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi:https://doi.org/10.33137/cpo j.v1i2.31326 abstract background: evidences of sustainable clinical benefits of bone-anchored prosthesis (bap) using osseointegrated fixation over typical socket-suspended prostheses are becoming more probing. this influx of individuals to be fitted with bap has pressed government organisations to adjust their policies. however, the appraisal of consumer’s experience for the provision of bap founded by government organisation is yet to be developed. this descriptive study shares the experience gained by a government organisation, namely the queensland artificial limb service (qals), while developing a specific bap-inclusive continuous quality improvement (cqi) procedure. objective(s): the primary objective was to present the methods and outcomes of key steps required to plan and create this cqi procedure. the secondary objective was to highlight key barriers and facilitators of the transition from a socket-focused to the proposed bap-inclusive cqi procedure. methodology: the re-design process of the cqi procedure for 65 current qals’s consumers with bap involved a two-step process for the planning (e.g., case-mix, stakeholder) and creation (e.g., diagnosis, technical options, cost). findings: prosthetists labour toward cqi procedure represented 1.3 hrs out of 22 hrs and aud$213 out of aud$3,300 or 6% of the whole procedure for the provision of bap. the time spent by a prosthetist, consumer and qals staff represented 24%, 24% and 53% of the time of the cqi procedure, respectively. the cost of prosthetist and qals staff labour represented 70% and 30% of the cqi procedure, respectively. conclusions: this descriptive study shares the workings and methodology that government organisations, such as qals, can use to re-design a cqi procedure for comprehensive appraisal of the provision of prosthesis that could be inclusive of bap and affordable while minimally time-consuming for prosthetists. the transition from a socket-focused to the proposed minimally disruptive bap-inclusive cqi procedure was facilitated by prior knowledge of bap treatment, early identification of the stakeholders and adaptation of current cqi procedure. article info received: october 25, 2018 accepted: december 11, 2018 published: december 12, 2018 keywords amputation; artificial limb; boneanchored prosthesis; quality improvement; osseointegrated implants; osseointegration; procedure; prosthesis; reimbursement. https://doi.org/10.33137/cpoj.v1i2.31326 mailto:laurentfrossard@outlook.com https://doi.org/10.33137/cpoj.v1i2.31326 https://doi.org/10.33137/cpoj.v1i2.31326 https://doi.org/10.33137/cpoj.v1i2.31326 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 2 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 list of abbreviations bap: bone-anchored prosthesis ssp: socket-suspended prostheses qals: queensland artificial limb service cqi: continuous quality improvement psp: prosthetic service provider cms: content management system pid: prosthetic issue document vos: validation of services pse: prosthetic service evaluation sf12: short form 12v2 health survey plus-m™: prosthetic limb users survey of mobility dva: rehabilitation appliance program of the department of veteran affairs ndis: national disability insurance scheme introduction strong demand for bone-anchored prostheses evidences of sustainable clinical benefits of boneanchored prosthesis (bap) using osseointegrated fixation over typical socket-suspended prostheses (ssp) are becoming more probing, particularly for young and active individuals with non-vascular transfemoral amputation.(1-4) clinical risks with bap particularly infection and breakage of components are currently deemed acceptable although yet to be resolved satisfactorily.(5-8) significant improvement in health-related quality of life has driven a steady demand from wide range of individuals with lower limb amputation.(1-4,7-26) indeed, surgical procedures are growing at an unprecedented pace worldwide.(18, 27, 28) health services delivery of bone-anchored prosthesis this influx of individuals fitted with osseointegrated fixation has pressed government organisations, like the queensland artificial limb service (qals), to adjust their policies for fair and equitable provision of bap.(18, 29) indeed, qals established such procedure allowing financial assistance for consumers choosing bap that involves seven processes costing aud$3,300 for 22 hrs of labour per patient during the treatment.(29) furthermore, cost cross-comparing and cost-effectiveness demonstrated health economic benefits of bap over ssp from government perspective.(30-32) for instance, provision of bap costed 21±41% more but increased quality-adjusted life-year by 17±5% compared to ssp leading to an indicative incremental cost effectiveness ratio of approximately aud $17,000 per quality-adjusted life-year. despite a partial compensation of the cost by quality-adjusted life-year, the provision of bap was deemed cost-effective since the incremental cost effectiveness ratio was noticeably below willingness to pay threshold.(33) need for government continuous quality improvement procedure appraisal of consumer’s experience for the provision of bap by government organisation is yet to be developed. a series of standardised surveys could assess delivery of particular prosthetic care and/or experience with prosthetic components (e.g., servqal, opus, quest).(34-41) however, their relevance to provision of specific bap care by government organisations is limited. qals has carried out a ssp-focused continuous quality improvement (cqi) procedure detailed below that has emerged through regular revisions over the last decade in response to best practice and legal obligations imposed by government as well as expectations from consumer advisory groups. whilst some aspects of this cqi procedure are relevant to the provision of bap, there is a need to further investigate developments of cqi procedure capable of appraising consumer’s experience for the provision of bap by government organisation. objectives the aim of this work was to improve government health service delivery of prosthetic care specific to individuals fitted with bap. the purpose of this process re-design descriptive study was to share the experience gained by a government organisation while developing a specific bapinclusive cqi. the primary objective was to present the methods of model re-design with particular emphasis on outcomes of key steps required to plan (e.g., casemix profiling, stakeholder analysis) and create (e.g., diagnosis, pros-cons analysis of technical options, cost) this specific cqi procedure. the secondary objective was to highlight key barriers and facilitators of the transition from a pre-existing ssp-focused to the proposed bap-inclusive cqi procedure. https://doi.org/10.33137/cpoj.v1i2.31326 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 3 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 methods setting the study followed ethical guidelines from the queensland health’s health innovation, investment and research office (hiiro) responsible for consultation, development and review of state-wide research ethics and research governance policies. this study was undertaken by qals in the jurisdiction of the queensland state government minister of health, australia. with a yearly budget of aud$5.4 million, qals provides equitable funding for prosthetic services to 3,600 active consumers annually through a network of up to 10 individual prosthetists referred to as prosthetic service provider (psp).(29, 30, 33) participants the development of the cqi procedure was led by a qals steering committee including qals management team, two researchers in health services, three psps and the five first consumers representing 8% of the qals’s population fitted with bap.(42, 43) study design the descriptive study started in july 2015, shortly after the whole qals’s procedure for provision of bap was completed.(29) as detailed in table 1, the development of the specific cqi procedure was achieved using the following two-step re-design process: • step 1 to plan the procedure, including: o step 1a identifying problems to solve using root cause analysis that involved case-mix profiling achieved by looking at typical demographics, amputation, as well as access to prosthetic care and funders data extracted from qals client information system. o step 1b identifying deliverables of the cqi procedure that involved stakeholder analysis using typical matrix ranking selected organisations in relation to their power and interest in cqi depending on capacity to influence allocation of resources and to provide prosthetic and medical care, respectively. stakeholders were classified as controllers (high power, low interest), promoters (high power, high interest), providers (low power, high interest) or advocates (low power, low interests).(44) • step 2 to create procedure including: o step 2a diagnosing quantitatively the suitability of the current ssp-focused cqi procedure by counting the number of sections, questions and possible answers in each evaluation form and by categorising the focus of each question as administration (e.g., consumer’s identification, processing status, quality control), service (e.g., labour associated with provision of prosthetic services and/or components), prosthesis (e.g., provision of repair, fitting, replacement of prosthetic components and/or cosmetic cover), socket (e.g., light, definitive) or bap (e.g., provision of all interventions to fit a bap). questions focusing on administration, service and bap were considered relevant while those focusing on prosthesis and socket were deemed partially suitable and irrelevant to appraisal of provision of bap, respectively. o step 2b exploring options for new specific cqi procedure that relied on pros-cons analysis of pathways and products investigated for administration and analysis of surveys and content management system (cms). o step 2c adapting the existing cqi procedure to each phasis of bap treatment, adjusting forms and estimating participants’ typical time commitment.(29) cost for psps’ contribution and internal labour (e.g., qals staff time) allocated to cqi procedure (e.g., data collection, entry and reporting) was set at hourly fee of aud$160 and aud$30, respectively. all costs are reported in australian dollars (1 australian dollar ≈ 0.63 euro ≈ 0.56 british pound ≈ 0.74 us dollar) according to 2017-18 prices. in all steps, the steering committee considered critical qualitative and quantitative information and applied a typical standards for interactive inquiry process and data-driven collaboration leading to consensus.(45) results definition of specific procedure case mix profile the characterisation of case-mix presented in table 2 involved the 65 qals consumers fitted with lower limb bap since 2011, representing 16% and 7% of existing bap population estimated at 400 in australia and 950 worldwide, respectively. https://doi.org/10.33137/cpoj.v1i2.31326 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 4 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 table 1. timeline and actions of the two-step process taken by the queensland artificial limb services (qals) to develop specific continuous quality improvement (cqi) procedure to appraise consumer’s experience for provision bone-anchored prostheses (bap). table 2. case-mix profile including demographics, amputation, access to care and funder information for the 65 queensland artificial limb services (qals) consumers with lower limb amputation treated with boneanchored prosthesis (bap) between 01/2011 and 01/2017 (psp: prosthetic service provider , dva: rehabilitation appliance program of the department of veteran affairs, ndis: national disability insurance scheme). stakeholders analysis twenty key stakeholders were identified with half operating at state or national levels as presented in figure 1c and further detailed in figure 2 (supplement). no stakeholder was identified as controllers. as expected, the six (30%) promoters involved the decisional entities around qals including consumer advisory group, in particular, as well as national government funding agencies. the seven (35%) providers involved all health professionals in the clinical teams responsible for osseointegration treatments in state and interstate, including essentially prosthetists. the seven (35%) advocates included mainly consumer support groups and professional associations as well as other artificial limbs services across australia. creation of specific procedure diagnosis of initial cqi procedure the appraisal of qals’ provision of prosthetic services involved a series of evaluations supported by three paper-based forms including a total of 73 items allowing 240 possible answers. as detailed in table 3, the review this cqi showed that: • evaluation a, involving seven steps, relied on prosthetic issue document (pid) to acknowledge psp’s service that triggers qals’ reimbursement. circulated by mail, the pid included 18 (25%) of all the questions that were completed by psps and consumers after each service. a total of 61% of the questions focused on the whole prosthesis. • evaluation b, involving four steps, relied on a validation of services (vos) form designed to assess a consumer’s satisfaction with quality of the prosthetic service delivered by psp. the vos included 25 (34%) of all the questions that were completed by qals staff while talking to consumers over the phone after each service. • evaluation c, involving four steps, relied on prosthetic service evaluation (pse) form designed to assess overall consumer’s experience with service provided by qals. the pse included 30 (41%) of all the questions that were completed by consumers yearly. overall, 51%, 40% and 9% of the questions were relevant, partially suitable and irrelevant to the development of cqi for bap, respectively. the content of the paper version of each form was manually tabulated by qals staff into a purposelydesigned cms, easily adjustable in-house in response to stakeholders’ regular changes in reporting expectations, including a series of spreadsheets organising entries, analysis and reporting of consumer experience information. a b c define project determine deliverables review literature •      identify problems to solve •      review regulatory obligations •      delivery of health care •      define aim, purpose and objectives •      conduct stakeholders analysis •      provision of prosthesis services •      profile case-mix •      determine reporting expectations •      consumer satisfaction survey a b c assess ssp-focused cqi explore options create bap-inclusive cqi •      review current process •      simulate new workflow •      adapt cqi procedure to bap treatment •      review current forms •      determine cost-benefits analysis •      adjust forms •      review current content management system •      choose most cost-effective procedure •      determine participants involvements step 1. plan bap cqi procedure (06/2016 12/2016) step 2. redisign bap cqi procedure (01/2017 07/2017) number percentage min max demographics male 50 77 female 15 23 age (years) 65 100 52 13 26 74 height (m) 58 89 1.75 0.10 1.50 1.94 mass (kg) 62 95 82.86 17.29 45.00 128.00 amputation timeline time since first amputation (years) 65 100 20 15 1 66 time since first surgery for bap (years) 64 98 3 1 0 6 cause trauma  44 68 vascular insufficiency 9 14 malignant neoplasma 6 9 level of amputation transfemoral 53 82 transtibial 9 14 through knee 3 5 hip disarticulation 1 2 number of amputations unilateral 58 89 bilateral 5 8 quadrilateral 2 3 access to prosthetic care distance-residence to psp (km) 60 92 145 212 5 1,345 distance-residence to qals (km) 62 95 364 499 5 1,771 funder qals 38 58 dva 8 12 ndis 12 18 mean sd rangeparticipants https://doi.org/10.33137/cpoj.v1i2.31326 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 5 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 figure 1. overview of initial and newly developed specific continuous quality improvement (cqi) procedure to appraise consumer’s experience for socket-suspended (ssp) and bone-anchored (bap) prostheses that involved (a) collection of data with clients and prosthetic service providers (psp), (b) analysis of the data relying on content management system (cms) and (c) reporting to stakeholders, respectively. table 3. overview of structure with number of sections, questions and possible answers and percentage of questions focusing on administration, service, prosthesis, socket or bone-anchored prosthesis (bap) for each initial form of the continuous quality improvement (cqi) procedure used by queensland artificial limb services (qals). pid: prosthetic issue document, vos: validation of services, pse: prosthetic service evaluation. explore options for specific cqi opportunity for redesigning a specific cqi procedure relying on new pathways, forms and cloud-based technological platform was initially investigated.(37, 46, 47) quote from external professional provider with relevant programming skills indicated that such project will require approximately 200 hrs of labour at the cost of aud$33,000. alternatively, keeping the current delivery pathway and adjusting forms and cms was considered. we made the assumption that these adjustments could be achieved in approximately 120 hrs for in-house knowledgeable staff labour at an internal cost of aud$3,600. the latter option was deemed the most sensible and cost-effective. creation of bap-inclusive cqi procedure a dynamic overview of the proposed bap-inclusive cqi procedure in figure 1 detailed the intersections between phases of the treatment and each of the three sequential evaluations with emphasis on contribution of participants, documents and forms used, the tasks achieved, cms used to collect, analysis and report consumer experiences outcomes. evaluations a and b were required to be completed after each service that occurred typically at least four times during the first year of the bap treatment between pre-operative consultation and fitting of definitive prosthesis. evaluation c occurs usually at least once a year after delivery of definitive prosthesis. the adaptation and reorganisation of all forms was achieved by implementing basic principles of socalled computerized adaptive testing.(48) the first part of all forms involving administration items, mainly focusing on identification of consumer and processing information, remained unchanged. however, a two-answer routing question was added at the end of administration section asking consumers what type of attachment they use. the ssp users were directed to the second part including essential questions in current forms related to socket and prosthesis cleaned of any bap related items. those using bap were directed to the third part including newly developed questions. practically, this third part in pid and vos forms required consumers to indicate at which of evaluation a evaluation b evaluation c cqi pid vos pse structure (number) sections 4 6 7 17 questions 18 25 30 73 answers 51 79 110 240 focus (percentage of questions) administration 24 57 7 28 service 0 0 53 22 prosthesis 61 37 30 40 socket 13 5 10 9 bap 2 1 0 1 1 https://doi.org/10.33137/cpoj.v1i2.31326 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 6 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 the five stages of the treatment they were at. developments of the third section in the pse form was more involved and lead to design of custommade survey including 32 questions as outlined in table 4 to assess clinical outcomes in six domains.(49) benefits were assessed into two domains including the health-related quality of life and mobility outcome using the standardized selfreport short form 12v2 health survey (sf12) and prosthetic limb users survey of mobility (plusm™) 12-item short forms, respectively.(39, 48) safety was assessed by self-reporting selected adverse events into four domains including fixation stability, fixation integrity, injuries as infections.(5) as presented in table 5, resources provided to psp’s efforts toward cqi procedure represented 1.3 hrs out of 22 hrs and aud$213 out of aud$3,300 or 6% of the whole procedure for the provision of the bap detailed previously.(29) the time spend by psp, consumer and qals staff represented approximately, 24%, 24% and 53% of the time of the whole procedure, respectively. the cost for reimbursement of psp’s and qals staff labour represented 70% and 30% of the total costs of the cqi administration per consumer, respectively. altogether, the typical total cost per consumer for the first year of treatment with bap was approximately aud$416. table 4. overview of 32 questions asked in third part of the prosthetic service evaluation (pse) form extracted from two standards surveys and eight specificallydesigned questions to assess six evaluation domains related to benefits and safety experienced by consumers fitted with bone-anchored prosthesis provided by qals. discussion outcomes this study revealed that a government organisation, such as qals, can redesign a cqi procedure for comprehensive appraisal of the provision of prosthesis that could be inclusive of bap while been minimally time-consuming for psps and affordable. the transition from a ssp-focused to the proposed minimally disruptive bap-inclusive cqi procedure was facilitated by the following redesign inputs: • capitalising on prior knowledge. initial understanding of specific rehabilitation program following bap treatment was gained during development of the qals overall procedure to support provision of bap. this elucidated involvements of psp in the delivery of services and components during treatment that was essential to determine workload and cost.(29) • identification of the stakeholders. early selection, organisation of key stakeholders helped to ascertain common and separate expectations and subsequently prioritise reporting requirements. • adapting current cqi procedure. redesigning a bap-specific cqi might lead to increased delivery efficiency and, more importantly, suitability of tailored forms providing distinctive results for this group of consumers. however, such parallel cqi procedure has several shortcomings including, but not limited to, confusion of consumers used to initial cqi, significant cost required to build dedicated cms, lack of consistency in reporting limiting benchmarking with other consumers.(49) alternatively, keeping the initial procedure relying on three evaluations but adapting the forms and cms was deemed the most sensible and cost-effective option. the main obstacles to the development of bapinclusive cqi procedure were associated with adjustments of pse form, particularly the selection of relevant outcomes to consider. only confounders of customer’s experience responsible for potential cross-correlation with provision of particular components and clinical outcomes were selected from classification of benefits and safety of bap standard customized 1. benefits 1.1. health-related quality of life ● short form 12v2 health survey (sf12) 12 x 1.2. mobility outcome ● prosthetic limb users survey of mobility (plus-m™) 12-item short form 12 x 2. safety 2.1. fixation stability ● has the osseointegrated fixation been formally diagnosed as loose by treating clinicians (e.g., surgeon) during the last 12 months? 1 x 2.2. fixation integrity ● have you experienced one or more bone fractures around the fixation including fracture of proximal joint (e.g., greater trochanter) during the last 12 months? 1 x ● how many times the internal part of the fixation in contact with the bone has been broken or replaced during the last 12 months? 1 x ● how many times the external part of the fixation connecting to the prosthesis (e.g., taper sleeve, abutment) has been repaired or replaced during the last 12 months? 1 x 2.3. injuries ● how many falls have you experienced in the last 12 months? 1 x 2.4. infection ● how many episodes of infections requiring a course of oral antibiotics for a week of less have you experienced in the last 12 months? 1 x ● how many episodes of infections requiring a course of oral or intravenous antibiotics for more than a week have you experienced in the last 12 months? 1 x ● have you been taking antibiotics continuously for more than four weeks during the last 12 months? 1 x number of questions domains and questions validation https://doi.org/10.33137/cpoj.v1i2.31326 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 7 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 treatment presented by frossard (2015) further detailed in figure 3 (supplement).(49) also challenging was to balance the selection of outcomes (inclusion vs exclusion), the choice of instrument to measure selected outcomes (e.g., preference on validated over in-house design selfreported surveys) and the overall length of the survey (e.g., preference on short over long forms of surveys). generic health-related quality of life measures were achieved using validated and widely used sf12 because the outcome could be readily benchmarked and converted in quality-adjusted lifeyear required for subsequent cost-utility analyses.(31, 33) mobility outcomes associated with actual usage of the prosthesis using t-score from plus-m™ could be supplemented by physical tasks such as time up and go and 6-minute walk accessible from consumer’s passport completed by psp after fitting of definitive components as described in frossard et al (2017), if needed.(29) table 5. breakdown of typical time commitment and costs associated with administration of the qals’s continuous quality improvement (cqi) procedure for evaluations a and b that repeated four times during the course of bap treatment and evaluation c that is conducted once and repeated yearly (prosthetic service provider (psp) labour = aud$160 per hour accordingly to the schedule of allowable fixed expenses in qals’ procedure, qals’ staff time = aud$30 per hour). for the safety outcomes, a decision was made to discard issues of soft tissues management, skin at stoma interface and phantom pain as they have no established links with prosthetic components. adverse events associated with fixation stability and integrity as well as injuries and infections were applicable since they might be inherent with the load generated by prosthetic components and, therefore, might have potential legal bearings. another hurdle to overcome was the lack of validated instruments to report advert events and complications. alternatively, a custom-made survey involving a short series of eight questions was collectively elaborated, pilot tested with selected consumers and implemented. limitations the pse form might be deemed onerous by some consumers because of redundancy of sf12 and plus-m with regular follow ups conducted by treating clinical teams. purposely designed survey lacked typical statistical validation. other limitations derived from typical intrinsic shortcomings of prospective study presenting the initial steps of action research cycle. beyond the scope of this study, the lack of actual long-term consumer’s experience data limited the validation of this proposed cqi procedure. the generalization of the outcomes must be considered carefully. the proposed cqi was purposely designed to fulfil specific needs for an australian state organisation providing funding for prosthetic care only. however, stakeholders and treatment pathways for provision of bap could differ between jurisdictions, particularly in european and north american countries.(33) indeed, the scalability of this cqi procedure within and between jurisdictions is yet to be established, particularly its capacity to integrate requests from broader stakeholders, the geographical spread of consumers extending to rural areas with limited access to a psp, the increasing number of treatment sites in australia and abroad as surgeries are more routinely performed. nonetheless, a series of valuable insights provided could be readily integrated by other organisations while customizing their own bap-inclusive cqi procedure, including the importance of understanding rehabilitation programs, identification and organisation of the stakeholders (e.g., local, regional, national), benefits and ways to adapt existing procedures (e.g., pathways, forms and cms), methods to determine involvement of participants (e.g., consumers, psps, funder) as well as consideration for confounders of customer’s experience with provision of bap (e.g., clinical benefits and safety). future studies future developments of the proposed cqi procedure will be facilitated by additional (hrs) ($) (hrs) ($) (hrs) ($) (hrs) ($) repeated at each phase of bap treatment (-2 to 9 months) evaluation a 1 psp send invoice for a service to qals 0.17 $27 0.17 $27 2 psp send pid to client 0.17 $27 0.17 $27 3 consumer acknowledge psp service using pid 0.25 $0 0.25 $0 4 consumer sent pid to qals 0.08 $0 0.08 $0 5 qals review invoice sent by psp 0.25 $8 0.25 $8 6 qals review pid sent by client 0.25 $8 0.25 $8 7 qals reimbourse psp for service 0.25 $8 0.25 $8 evaluation b 1 consumer evaluate psp and qals service using vos 0.25 $0 0.25 $0 2 consumer sent vos to qals 0.08 $0 0.08 $0 3 qals review vos sent by client 0.50 $15 0.50 $15 4 qals tabulate information into registry 0.25 $8 0.25 $8 0.33 $53 0.67 $0 1.50 $45 2.50 $98 1.33 $213 2.67 $0 6.00 $180 10.00 $393 one-off yearly upon completion of bap treatment (12 months) evaluation c 1 client evaluate psp and qals service using pse 0.25 $0 2 client sent pse to qals 0.08 $0 3 qals review pse sent by client 0.50 $15 0.50 $15 4 qals tabulate information into registry 0.25 $8 0.25 $8 0.00 $0 0.00 $0 0.75 $23 1.08 $23 1.33 $213 2.67 $0 6.75 $203 11.08 $416 total for yearly assessment total for each phase of treatment total for all phases of treatment total for year of treatment consumerpsp qals overall step participant task https://doi.org/10.33137/cpoj.v1i2.31326 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 8 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 longitudinal studies providing experience outcomes for a large cohort of bap users over an extended period of time that could be benchmarked against other bap or ssp users. possibilities for additional cross-sectional studies are endless, particularly for the ones correlating experience with provision of bap accordingly to technological platform supporting cqi procedure (e.g., online forms, cloud-based cms), provision standards of components (e.g., microprocessor prosthetic knees) and clinical outcomes (e.g., health-related quality of life, mobility, fixation stability and integrity, injuries, infections) with different type of fixations (e.g., screw-type, pressfit).(2, 50-54) conclusions the early development of a cqi procedure, including the management of barriers and transferable facilitators, to appraise the provision of bap by a governmental organization was shared for the first time. this work was an initial effort toward the assessment of fair and equitable governmental financial assistance programs for individuals choosing bap. altogether, this study should be considered as a stepping-stone providing a working approach for bap-inclusive cqi to other organizations worldwide. source of support this study has been funded by queensland artificial limb service. acknowledgement the authors wish to express their gratitude to john vasil for his contribution to the development of this project as well as fiona barnett, stephan laux, barry leech and luke lorenzin for their insight into prosthetic care. declaration of conflicting interests the authors have no conflict of interest. author contribution • laurent frossard has developed the study design including collection, analysis, presentation the data as well as writing this manuscript. • luciann ferrada has contributed to the collection and analysis of the data as well as the writing of the manuscript. • tanya quincey has contributed to the collection and analysis of the data as well as the writing of the manuscript. • brendan burkett has contributed to the writing and reviewing of the manuscript. • debra berg has lead the whole project including the study design, collection, analysis, presentation the data as well as writing this manuscript. references 1. hebert js, rehani m, stiegelmar r. osseointegration for lower-limb amputation: a systematic 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https://doi.org/10.1177/0309364617740239 https://doi.org/10.1080/03093640802403803 https://doi.org/10.1080/03093640208726623 https://doi.org/10.1080/03093640308726682 https://doi.org/10.1177/0309364616637957 https://doi.org/10.1080/09638280600948375 https://doi.org/10.1080/0963828021000031197 https://doi.org/10.1007/s40258-013-0023-3 https://doi.org/10.1007/s40258-013-0023-3 https://doi.org/10.1007/s40258-015-0200-7 https://doi.org/10.1186/1471-2458-13-428 https://doi.org/10.2522/ptj.20060280 https://doi.org/10.1177/0309364617728118 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 11 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 international conference advances in orthopaedic osseointegration; las vegas, nevada, usa2015. p. 20. 50. pitkin m. design features of implants for direct skeletal attachment of limb prostheses. j biomed mater res a. 2013 nov;101(11):3339-48. doi: 10.1002/jbm.a.34606 51. pitkin m. one lesson from arthroplasty to osseointegrationin search for better fixation of in-bone implanted prosthesis. j rehabil res dev. 2008;45(4):614. 52. orendurff ms. literature review of published research investigating microprocessor-controlled prosthetic knees: 2010 – 2012. jpo: journal of prosthetics and orthotics. 2013;25(4s). doi: 10.1097/jpo.0b013e3182a8a922 53. van der linde h, hofstad cj, geurts ac, postema k, geertzen jh, van limbeek j. a systematic literature review of the effect of different prosthetic components on human functioning with a lower-limb prosthesis. j rehabil res dev. 2004 jul;41(4):555-70. pubmed pmid: 15558384. epub 2004/11/24. eng. 54. collins dm, karmarkar a, relich r, pasquina pf, cooper ra. review of research on prosthetic devices for lower extremity amputation. crit rev biomed eng. 2006;34(5):379-438. doi: 10.1615/critrevbiomedeng.v34.i5.20 https://doi.org/10.33137/cpoj.v1i2.31326 https://doi.org/10.1002/jbm.a.34606 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 12 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 supplements development of a government continuous quality improvement procedure for the provision of bone-anchored prosthesis using osseointegration fixation figure 2. stakeholder matrix included the groups of controllers, promoters, providers and advocates of the continuous quality improvement (cqi) procedure depending on power (capacity to influence allocation of resources) and interest (capacity to provide prosthetic and medical care). p o w e r c a p a c it y t o i n fl u e n c e r e s o u rc e s l o w h ig h controllers promoters • state governmental funding agencies: o consumer advisory group (cag) o qals’s executive committee o medical aids subsidy scheme (mass) o queensland health • national governmental funding agencies: o department of veteran affairs (dva) o national disability insurance scheme (ndis) • state consumer support group: o amputees and families support group qld inc • national consumer support group: o limb4life • national professional associations: o australian national membership society of the international society of prosthetic and orthotics (anms-ispo) o australian orthotic and prosthetic association (aopa) • artificial limbs services in other states: o orthotics and prosthetics south australia (opsa) o enablensw o victorian artificial limb program (valp) • state service providers: o prosthetic service providers (psp) o physiotherapists o occupation therapists o general practitioners o clinical teams • national service providers: o prosthetic service providers (psp) o surgeons advocates providers low high capacity of provide medical and prosthetic care interest https://doi.org/10.33137/cpoj.v1i2.31326 frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. canadian prosthetics & orthotics journal, volume 1, issue 2, no 4, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.31326 13 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 figure 3. overview of evaluation framework to extract clinical benefits (top) and harms (bottom) as presented in “frossard l. evaluation framework to assess benefits and harms of bone-anchored prosthesis. 6th international conference advances in orthopaedic osseointegration. 2015. las vegas, nevada, usa. p 20” available from: https://eprints.qut.edu.au/82763/ https://doi.org/10.33137/cpoj.v1i2.31326 http://eprints.qut.edu.au/82763/1/2015-osos-conf-abs%2001-evaluation_framework-eprint-all_01.pdf https://eprints.qut.edu.au/82763/ lechler k, and kristjansson k. the importance of additional mid swing toe clearance for amputees. canadian prosthetics & orthotics journal. volume1, issue2, no.1, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30813 2 0 1 8 2 0 1 8 professional opinion issn: 2561-987x all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x volume 1, issue 2 2 0 1 8 https://doi.org/10.33137/cpoj.v1i2.30813 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com lechler k, and kristjansson k. the importance of additional mid swing toe clearance for amputees. canadian prosthetics & orthotics journal. volume1, issue2, no.1, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30813 1 open access the importance of additional mid swing toe clearance for amputees volume 1, issue 2, article no.1, september 2018 professional opinion the importance of additional mid swing toe clearance for amputees lechler k*, kristjansson k össur medical office, r&d össur ehf, reykjavik, iceland. introduction the shortest distance between the ground and the toe during level ground walking, referred to as the minimum toe clearance (mtc), occurs during mid swing phase (mid swing toe clearance: mstc) and for abled bodies this averages to be around 15 mm.1 this is the point in time during the gait phase where tripping is most likely to occur.2–4 trip-related falls have been identified as the leading cause of falls for community-dwelling, middle-aged and older adults.5– 7 looking at elderly non-amputated women only, trips amount for up to 33% of the causes for their falling.8 whereas women are more likely to fall while walking men are more likely to fall from loss of support by an external object rather than tripping, as well as falling while sitting down or rising from sitting.9 while most elderly amputees are men10 the risk of amputees in general to fall over a one-year period is 50% or higher.11 historically the first reported prosthetic leg offering additional toe clearance in swing dates back to 1805 (fig. 1,2,3)12, but still today most conventional prosthetic feet do not provide features for additional mstc. this is despite the fact that historically various stumble preventing mechanisms for both trans-tibial and trans-femoral community ambulators have been offered since the early days of the industrial revolution, underlining the longstanding awareness of the importance of trips and stumbles as a cause for falls by amputtees.12 why do many prosthetics solutions not provide for minimum toe clearance? the main reason for insufficient mstc is the fact that conventional prosthetic feet do not dorsiflex during swing which places the mstc on the prosthetic side below the mtc.13 another well recognized reason is the vertical displacement between the socket and the residual during swing phase (pistoning) resulting in functional elongation of the prosthetic leg.14-16 citation lechler k, and kristjansson k. the importance of additional mid swing toe clearance for amputees. canadian prosthetics & orthotics journal. volume1, issue2, no.1, 2018. doi: https://doi.org/10.33137/cpoj.v1i2 .30813 keywords prosthetics, toe clearance, lower limb prosthesis, mobility, prosthetic foot, polycentric axis knees, amputee. *corresponding author knut lechler, medical director prosthetics, össur ehf, grjothals 1-5, 110 reykjavik, iceland. email: klechler@ossur.com tel: +49 151 50459110. disclosure: full time employees of a medical device manufacturer, össur ehf. doi: https://doi.org/10.33137/cpoj.v1i2.30813 abstract increased prosthetic hip to toe distance and insufficient mid swing toe clearance of a prosthetic foot is a well-recognized inadequacy for lower limb prosthesis users with wide and possible grave consequences on their ambulation capabilities. most important are increased risk of falls and abnormal compensatory gait patterns with secondary unwanted physical effect like generally deceased mobility, muscular-skeletal pain and joint degeneration, i.e. osteoarthritis, with possible significant health economic effect. even though insufficient toe clearance can be device related and technically or even intentionally induced for attaining equal length of the lower extremities in a neutral standing position or the stance phase, it is important to be aware of available technical solutions that can counteract the problem, like swing phase dorsiflexing feet, vacuum suspension systems, polycentric axis knees rather than single-axis knees and adequate knee flexion in early swing and swingflexion assistance in the case of bionic knees. https://doi.org/10.33137/cpoj.v1i2.30813 https://doi.org/10.33137/cpoj.v1i2.30813 mailto:klechler@ossur.com https://doi.org/10.33137/cpoj.v1i2.30813 lechler k, and kristjansson k. the importance of additional mid swing toe clearance for amputees. canadian prosthetics & orthotics journal. volume1, issue2, no.1, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30813 2 open access the importance of additional mid swing toe clearance for amputees volume 1, issue 2, article no.1, september 2018 equal leg length in the stance phase yields an increased functional leg length in the swing phase of at least 16mm for a non-amputee.17,18 the functional prosthetic leg length with single axis knee is even further increased,18 resulting in a 22 mm lower mstc compared to polycentric knees.19 in a 3d simulation with data from trans-femoral amputees’ single-axis knees provided the least clearance (4.6 cm) during prosthetic swing phase, followed by fourbar knees (5.8 cm), and the two ankle mechanisms (6.4 and 8.7 cm).19 biomechanical and physical effect of insufficient toe clearance for the purpose of overcoming amputees’ experience of vertical displacement between socket and residual and the associated functional elongation of the prosthetic leg in swing phase14–16 the prosthesis is commonly aligned significantly shorter than the sound side. amongst 113 transfemoral and trans-tibial amputees 70 % were found to have a significant leg length discrepancy radiographically while balanced standing due to shorter alignment of the prosthesis compared to the sound side.20 gaunaurd et. al. showed that 66% of trans-femoral amputees had leg length discrepancies and for 57% the prosthetic side was shorter.21 back pain is very common in lower limb amputees22 and has been linked to poor prosthetic fit and alignment, postural changes, leg-length discrepancy, amputation level, and general deconditioning.23 the significance of this approach of leg length misalignment for the purpose of trying to make up for functional leg length increase during swing and the associated decrease in the mstc is that leg length discrepancy can lead to various health problems like back pain24 and studies have shown it to contribute to back pain in amputees.25,26 not trying to adjust for the functional prosthetic leg length increase and to fit the prosthesis at an equal length to the sound side also carries with it a problem as pistoning in the socket and the changes in the trajectory of the prosthetic foot changes the point in time at which the physical maximum functional leg length occurs. for this additional functional swing phase leg length and time shift the amputees will try to compensate by developing their individual adaptation mechanisms. one is to elevate the contralateral side by early heel rise resulting in what is referred to as “vaulting”. another is an arc-like movement of the prosthetic limb referred to as “circumduction” and thirdly a lateral trunk inclination with definite raising of the hip on the prosthesis side. as a matter of fact, these three are the basic and main gait abnormalities characteristic for lower limb amputee in various degrees of combinations, even obvious to a lay observer. both stationary and functional leg length discrepancies cause abnormal forces on bones and joints likely to lead to degenerative conditions like osteoarthritis which has been found to be more prevalent in the contralateral limb than the residual limb of people with amputation. 27,28 the increased prevalence of osteoarthritis is of concern, especially for people who have lived with an amputation for a longer time.28 this actually turns out to be the case for many traumatic amputees who have been shown to have a significantly increased risk of suffering from osteoarthritis.29 the health economic relevance of toe clearance the proven relationship between insufficient toe clearance to trips and hence falls bring this feature into the scope of possible significant health economic effects. although there is scarce published literature on the economic costs of falls within the amputee population, the costs of falls among older adults have been well studied. the estimated average one-year cost attributed to an elderly adult falling and requiring subsequent medical attention is between $3,408 and $4,872. furthermore, if the fall results in a hospitalization, the cost may increase up to $35,144 on average. within this population, it is estimated that up to 1 in every 9 falls will lead to hospitalization.30 figure 1. anglesey tt and tf (1805) figure 2. erfurt tf (1880) figure 3. martin tt (1857) lechler k, and kristjansson k. the importance of additional mid swing toe clearance for amputees. canadian prosthetics & orthotics journal. volume1, issue2, no.1, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30813 3 open access the importance of additional mid swing toe clearance for amputees volume 1, issue 2, article no.1, september 2018 a study on falls of amputees shows that up to 40% of their falls result in an injury and every other fall necessitates medical attention, which is higher than for the non-amputated elderly which has been estimated to be 30%.31 one study on trans-femorals indicated an estimated cost of $25,652 at 6 months, for falls resulting in hospitalization, similar to the costs within the elderly.32 direct medical costs of all falls in the usa was $31.3 billion in 2015, up from $30.3 billion in 2012.33 possible secondary health economic effect through backand musculoskeletal pain and degenerative joint disease is also of real significance with osteoarthritis already accounting for 2% of years lived with disabilities.34 oa is a rising concern specifically to amputees because they have a higher risk to suffer from hip and knee osteoarthritis.35 osteoarthritis often coexist with an amputation as pain does28 and even further limits amputees in their mobility.36 osteoarthritis in the contralateral limb knee is 17 times higher than in age-matched nonamputees35 and knee pain in unilateral amputees is twice as common.35 imaging studies have confirmed the increased prevalence of degenerative changes in the contralateral knee.37,38 since ttas are known to load their intact limb to a greater extent than their prosthetic limb during gait,23 the marked asymmetry in knee pain and degeneration suggests that mechanical loading factors are likely an important contributor to the increased incidence of oa. not only asymmetries but also minor compensations can increase stress on the contralateral limb and possibly predispose the long-term prosthesis wearer to premature degenerative arthritis.39-40 remedies for insufficient toe clearance the most straight forward and natural action is the provision of prosthetic feet that dorsiflex in the swing phase and thereby compensating for the elongation in swing phase at the same time allowing for leg length equality in the stance phase or when standing. motorized and actively dorsiflexing prosthetic ankles have shown to significantly increase mstc41 by about 70% and increase in mstc of 25.6 ± 5.4 mm has been shown to lead to a reduction in falls42 over a one-year period for community dwelling amputees. hydraulic ankles with dorsiflexion in swing have also been shown to increase the mstc.43 a recent study has shown in addition to increased mstc during level ground walking that this can also be provided for during incline and decline walking (figure 4).44 an anecdotal user report from this same trial states: “my work environment involves walking through sloped tunnels and up/down stairs. i usually trip 1-3 times per day with my prescribed foot, but i never tripped with the proprio-foot!”. several studies had previously looked at and compared the mstc of conventional esar feet versus dorsiflexing ankles (table 1). table 1: comparison of prosthetic side toe clearances in mm. other technical solutions that can improve the mstc are vacuum suspension systems for reduced pistoning and functional swing phase prosthetic leg length increase. a study by rosenblatt where falling rate and pattern was tracked over a one-year period for 27 amputees (15 vacuum assisted socket suspension (vass) users, 12 non-vass users) showed 75% less risk of vass trans-tibial amputee users having multiple falls compared to non-vass users. toe clearance on the prosthetic side level (mm) slope (mm) decline (mm) fallers, rosenblatt 2017 12.3 non-fallers, rosenblatt 2017 25.6 hydraulic, johnson 2014 20.7 motorized, fradet 2010 16.0 12.0 motorized, rosenblatt 2014 33.6 motorized, lamers 2018* 14.6* 18.4* 11.7* * compared and in addition to sound side figure 4. mtc with mpa(proprio), mpa-locked and conventional esar in level ground.44 lechler k, and kristjansson k. the importance of additional mid swing toe clearance for amputees. canadian prosthetics & orthotics journal. volume1, issue2, no.1, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30813 4 open access the importance of additional mid swing toe clearance for amputees volume 1, issue 2, article no.1, september 2018 even though less effective than providing dorsiflexion ankles, selecting polycentric knees over single axis knees also helps with the toe clearance as previously outlined.19 also providing a bionic knee like the rheo knee that has a rapid foot off velocity results in a higher mstc compared to single axis knees.45 additionally, the rapid toe off velocity and lower hip torque qualities of the rheo knee results in earlier toe off at a slower than preferred walking speed and significantly less vaulting of the intact ankle, compared to for example a hydraulic knee (p = 0,028).46 summary providing sufficient toe clearance on the prosthetic side allows aligning the prosthesis more equally and favorable influence in short term on low back pain and in longer term on side effects like lumbar scoliosis and osteoarthritis. most importantly added toe clearance should results in fewer trips and stumbles resulting in decrease in falls. all of this can possibly result in significantly less health economic burden. a large study on patients having undergone hip arthroplasty (n=753) shows that leg length discrepancy reduces satisfaction and functional outcome after hip arthroplasty.47 reducing risks of falls reduces the degree of disability of amputees by improving their mobility and hence improves their quality 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amputees. arch phys med rehabil.2009; 90, 440–446. https://doi.org/10.1016/j.apmr.2008.08.220 37.geertzen jh, bosmans j c, van der schans cp, dijkstra pu. claimed walking distance of lower limb amputees. disabil rehabil. 2005; 27, 101–104. https://doi.org/10.1080/09638280400009345 38.norvell dc, czerniecki jm, reiber ge, maynard c, pecoraro ja, weiss ns. the prevalence of knee pain and symptomatic knee osteoarthritis among veteran traumatic amputees and nonamputees. arch phys med rehabil.2005; 86, 487–493. https://doi.org/10.1016/j.apmr.2004.04.034 39.lemaire ed, fisher fr. osteoarthritis and elderly amputee gait. arch phys med rehabil. 1994;75, 1094– 1099. 40.hurley grb, mckenney r, robinson m, zadravec m, pierrynowski mr. the role of the contralateral limb in below-knee amputee gait. prosthet orthot int. 1990;14, 33–42. 41.rosenblatt nj, bauer a, rotter d, grabiner md. active dorsiflexing prostheses may reduce trip-related fall risk in people with transtibial amputation. j rehabil res dev. 2014;51, 1229–1242. http://dx.doi.org/10.1682/jrrd.2014.01.0031 42.rosenblatt nj, bauer a, grabiner md. relating minimum toe clearance to prospective, self-reported, triprelated stumbles in the community. prosthet orthot int. 2017;41(4):387-392. doi:10.1177/0309364616650085 https://doi.org/10.1109/tnsre.2012.2224885 https://doi.org/10.1177%2f0309364611407676 https://doi.org/10.1053/apmr.2001.21962 https://doi.org/10.1016/j.apmr.2005.06.012 https://doi.org/10.1016/s0966-6362(02)00066-8 https://doi.org/10.7205/milmed-d-15-00510 https://doi.org/10.7205/milmed-d-15-00510 https://doi.org/10.1111/j.1532-5415.2010.02816.x https://doi.org/10.1177%2f0309364617704804 https://doi.org/10.1016/j.jsr.2016.05.001 https://doi.org/10.1016/j.berh.2014.08.002 https://doi.org/10.1016/j.apmr.2008.08.220 https://doi.org/10.1080/09638280400009345 https://doi.org/10.1016/j.apmr.2004.04.034 http://dx.doi.org/10.1682/jrrd.2014.01.0031 https://doi.org/10.1177/0309364616650085 lechler k, and kristjansson k. the importance of additional mid swing toe clearance for amputees. canadian prosthetics & orthotics journal. volume1, issue2, no.1, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30813 6 open access the importance of additional mid swing toe clearance for amputees volume 1, issue 2, article no.1, september 2018 43.johnson l, de ashaar, munjal r, kulkarni j, buckley jg. toe clearance when walking in people with unilateral transtibial amputation: effects of passive hydraulic ankle. j rehabil res dev. 2014; 51, 429–437. doi:10.1682/jrrd.2013.05.0126 44.lamers e. effects of a new adaptive ankle prosthesis on level and sloped walking. 42nd annu meet am soc biomech. rochester mn usa (2018). 45.johansson jl, sherrill dm, riley po, bonato p, herr h. a clinical comparison of variable-damping and mechanically passive prosthetic knee devices. am j phys med rehabil. 2005; 84, 563–575. doi: 10.1097/01.phm.0000174665.74933.0b 46. prinsen ec, nederhand mj, sveinsdóttir hs, prins mr, van der meer f, koopman hfjm, rietman js. the influence of a user-adaptive prosthetic knee across varying walking speeds: a randomized cross-over trial. gait posture. 2017; 51, 254–260. doi:10.1016/j.gaitpost.2016.11.015 47.röder c, vogel r, burri l, dietrich d, staub lp. total hip arthroplasty: leg length inequality impairs functional outcomes and patient satisfaction. bmc musculoskelet disord.2012; 13, 95. doi:10.1186/1471-2474-13-95 48.asano m, rushton p, miller wc, deathe ba. predictors of quality of life among individuals who have a lower limb amputation. prosthet orthot int.2008; 32, 231–243. doi:10.1080/03093640802024955 authors biography mr. knut lechler, össur medical director prosthetics, is a cpo-d at ossur ehf, reykjavik, iceland and has been in that position for 7 years. he graduated in 1991 as cpo (master) and used to work as a freelancer before he started in the industry in 1999 (flex-foot inc.). since 2001 he is with össur. knut lechler is an active member of the isotc 168 wg1. dr. kristleifur kristjansson, medical officer and vp of clinical affairs, is a medical doctor and has been in his current position at össur for 6 years. dr. kristjansson was a vp of clinical collaborations at decode genetics for 16 years and holds a consulting position at the university hospital in reykjavik iceland as a pediatrician and geneticist. https://doi.org/10.1682/jrrd.2013.05.0126 https://doi.org/10.1016/j.gaitpost.2016.11.015 https://doi.org/10.1186/1471-2474-13-95 https://doi.org/10.1080/03093640802024955 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives miller ta, wurdeman s, paul r, forthofer m. the value of health economics and outcomes research in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.8. https://doi.org/10.33137/cpoj.v4i2.35959 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.35959 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 miller ta, wurdeman s, paul r, forthofer m. the value of health economics and outcomes research in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.8. https://doi.org/10.33137/cpoj.v4i2.35959 stakeholder perspectives the value of health economics and outcomes research in prosthetics and orthotics miller ta.1,2 *, wurdeman s.1,3, paul r.4, forthofer m.2 1 department of clinical and scientific affairs, hanger clinic, austin, texas, usa. 2 college of health and human services, university of north carolina at charlotte, charlotte, north carolina, usa. 3 department of biomechanics, the university of nebraska at omaha, omaha, nebraska, usa. 4 department of public health sciences, school of data science, university of north carolina charlotte, north carolina, usa. introduction rehabilitation is can be defined as a problem-solving process or service aimed at reducing disability or impairment experienced by an individual as a result of disability or injury ultimately to improve function.1,2 unmet needs for rehabilitation services and health systems are often undervalued services.2,3 individuals who have a lower limb amputation (lla) or require orthotic bracing experience numerous, overlapping difficulties with respect to overall physical health including functional recovery as well as social and mental health.4-7 as healthcare costs have increased, the economic burden associated with care for those with chronic conditions, especially functional impairment and disability, remains high.8-11 rehabilitation is essential if individuals are to regain functional independence, return to adls and good overall health whether it be in a post-amputation condition or a progressive neuromusculoskeletal condition. yet, real world evidence (rwe) on rehabilitation outcomes among those with lla and neuromusculoskeletal conditions requiring orthotic intervention is sparse. there is a paucity of information relating to timing of orthosis or prosthesis receipt in the care pathway, effectiveness of interventions, overall costs and utilization. hence, there is a need for more rwe on factors that influence outcomes to help inform clinical practice and guide clinicians, strengthen policy, and influence patient-health while being cost-effective.12,13 the purpose of this paper is to explicate health economics and outcomes research (heor) as a field, discuss recent applications in orthotics and prosthetics (o&p), and the need for continued health economic research. recent publications on economic science provided perspectives from consumers, providers, and manufacturers,14-16 which highlighted that health economic analyses and science is not about reducing access to essential o&p care but to optimize outcomes and access. healthcare decision makers today are often faced with the need to select from multiple treatment options, the timing of any such treatment, or determine alternative appropriate care plans. however, the benefits and associated costs of these different interventions or plans can vary greatly. the open access volume 4, issue 2, article no.8. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract the demand has increased for evidence regarding the effectiveness and value of prosthetic and orthotic rehabilitation interventions. clinicians and managers are under pressure to provide treatment recommendations and demonstrate effectiveness through outcomes. it is often assumed that rehabilitation interventions, including the provision of custom-made and custom-fit orthotic and prosthetic devices, are beneficial to patients. assessing the value of orthotic and prosthetic services has become more critical to continue to ensure equitable access to needed services. health economics and outcomes research methods serve as tools to gauge the value of prosthetic and orthotic rehabilitation interventions. the purpose of this article is to provide an overview of the current need of health economics and outcomes research in orthotics and prosthetics, to introduce common economic methods that assist to generate real-world evidence, and to discusses the potential value of economic methods for clinicians and clinical practice. citation miller t.a, wurdeman s, paul r, forthofer m. the value of health economics and outcomes research in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.8. https://doi.org/10.33137/cpoj.v4i2.35959 keywords health economics, prosthetics, orthotics, outcomes research, rehabilitation * corresponding author taavy a miller, phd, cpo department of clinical and scientific affairs, hanger clinic, austin, texas, usa. e-mail: tamiller@hanger.com orcid id: https://orcid.org/0000-0001-7117-6124 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.35959 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.35959 mailto:tamiller@hanger.com https://orcid.org/0000-0001-7117-6124 2 miller ta, wurdeman s, paul r, forthofer m. the value of health economics and outcomes research in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.8. https://doi.org/10.33137/cpoj.v4i2.35959 issn: 2561-987x the value of health economics and outcomes research miller et al. 2021 cpoj special s p e c ia l i s s u e benefits can be clinical, economic, or may include more humanistic outcomes. humanistic outcomes, such as patient experiences, are more challenging to measure as they cannot be evaluated by clinicians but rather are patientreported (e.g. pain and quality of life). heor applications (i.e. types of economic evaluations) include broad, scientifically vigorous methods and tools used to assess the effectiveness and impact of specific interventions (e.g. specific knee selection) in order to adequately compare and choose treatments or devices among the available options (table 1). table 1: examples of the basic types of economic evaluations and preference-based analyses with applications in o&p or related rehabilitation literature. type of evaluation definition example in literature costeffectiveness analysis (cea) a comparison between the costs and an outcome for a specific treatment or intervention (e.g. the cost of providing a prosthesis or orthosis compared to not providing one) dobson, davanzo & associates llc: cost effectiveness of prosthesis among medicare beneficiaries17 cost utility analysis (cua) often referred to as a sub-type of cea; specifically, an analysis that includes health utility (i.e. health related quality of life or quality adjusted life year/qaly) gerzeli et al: cost utility analysis comparing different microprocessor knees among workingage patients in italy18 cost benefit analysis (cba) an alternative to cea, monetary value is placed on both costs of treatment and effectiveness; all costs (i.e. direct and indirect) are considered glassman et al.: costs and benefits (outcomes) of several non-surgical treatments compared for adult scoliosis19 cost minimization analysis an analysis conducted to identify a least costly alternative of effective treatment (e.g. telerehabilitation versus face to face) *unable to identify a specific o&p example costconsequence an analysis used to describe an intervention or compare two or more interventions including the effect of costs and outcomes gil et al: cost comparison of limb salvage versus amputation20 and edwards et al.: markov model assessing cost consequence of prosthetic rehabilitation21 multi-criteria decision analysis or discrete choice experiment (preference studies) a structured process for making decisions and is a tool that can extend traditional economic analysis methods to include the patient perspective and assist with prioritization of healthcare interventions geidl et al: assessing exercise preferences for patients after a stroke22 previous work has demonstrated that it is possible to assess healthcare resource utilization and costs through the use of a population-based, nationally validated claims dataset while providing meaningful insight into clinical care and patient outcomes.17,23 furthermore, decision-making based on the preferences of patients (e.g. health state preference, utility) along with traditional economic analyses (e.g. costeffectiveness studies) will contribute to optimizing patient outcomes. these types of health economic concepts are important to understand as the o&p practitioner and key stakeholders are continuing to navigate the increasingly challenging demands of the healthcare system. rehabilitation services currently, there is limited evidence in o&p rehabilitation regarding outcome factors related to delivery of care such as patient preferences, accessibility and timing of provision, economic impact and value of rehabilitation services for people with functional impairment or decreased mobility.24 without adequate evidence on the performance and effectiveness of o&p rehabilitation treatment, scrutiny of services will continue by policymakers and payers, potentially resulting in reduced access to needed services.2 physical medicine and rehabilitation service is a broad category in healthcare targeting a wide population (children, adults, and older people) with a range of conditions impacting function and participation, including diverse interventions (rehabilitation medicine, orthopedic surgery, physical therapy, occupational therapy, prosthetics, orthotics, and assistive devices) and outcomes.25 the primary goal of physical rehabilitation services is to address individual needs towards the reduction of symptoms and to promote independence in daily activities or participation,26 which includes predisposing (e.g. demographic characteristics such as amputation level), enabling (e.g. environmental, social, health insurance status), and need (e.g. modifiable health status such as comorbid health conditions) factors, which each contribute towards overall rehabilitation use.2,27 clinical and policy decisions about appropriate and optimal rehabilitation interventions require evidence on resource allocation, costs and effectiveness.25 rehabilitation services are often undervalued by health systems due to being under-funded, under-researched and under-provided in many contexts.2,25 lack of evidence and knowledge on patient outcomes due to physical rehabilitation services result in reduced access to appropriate services, which includes access to assistive devices (e.g. orthoses and prostheses) and physical therapy.28,29 https://doi.org/10.33137/cpoj.v4i2.35959 3 miller ta, wurdeman s, paul r, forthofer m. the value of health economics and outcomes research in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.8. https://doi.org/10.33137/cpoj.v4i2.35959 issn: 2561-987x the value of health economics and outcomes research miller et al. 2021 cpoj special s p e c ia l i s s u e lack of understanding of value of prosthetic rehabilitation the demand for value-based care in rehabilitation is growing while the concept of value is multidimensional and may be defined differently depending on the stakeholder (e.g. patient, payer, provider or society). the traditional economic definition of value is dependent on cost, quality and willingness to pay for a good or service.12 the components that comprise how we gauge the value of an intervention or healthcare service is based on perspective, whether societal or individual, as well as cultural perceptions.12,17 therefore, it is important to assess health interventions and resultant outcomes (functional health or economic) within the context of a single country or region. the approach to place value and quantify treatment effects is more widely being applied with payers and policymakers asking for evidence.8,17 the field of physical rehabilitation has perhaps fallen behind other services in the amount of value-based evidence.2,13 o&p care, a niche subset within physical rehabilitation, has arguably fallen even further behind. it is critical that as a field, we collaboratively work to gauge value based on key benefits (including clinician and patient reported measures) that demonstrate real-world effectiveness of the interventions, as o&p devices are unique. for example, consider post-amputation recovery, aside from differences in patient acuity, a high post-operative mortality rate suggests that quality improvement programs need to address the prosthetic rehabilitation needs. for instance, being mobile and physically active improves cardiovascular health, reduces the negative effects of diabetes and reduces depression or feelings of isolation.30 patient satisfaction and quality of life are associated with less time between amputation surgery and delivery of a prosthesis.31 furthermore, satisfaction and quality of life are correlated with mobility and patients with no prosthesis are unable to be as physically mobile.31 without prosthetic care individuals have increased risk of clinical complications including increases in healthcare utilization and spending.17 based on the current research, it is reasonable to propose that lack of prosthetic rehabilitation negatively influences mobility, satisfaction and quality of life. further investigation is needed to establish why wearing a prosthetic device improves survival and potentially reduces overall utilization or economic burden.32 without this data, there is an underappreciation for the true value of prosthetic rehabilitation. standards of care and rehabilitation guidelines postamputation the standards of care post-amputation are limited aside from the immediate surgical care protocols. furthermore, of the limited guidelines published, there is low physician adherence or awareness of the processes.33 heor studies can inform how a reduction in access to rehabilitation services reduces individual health outcomes. the integration of health economic studies and evidence into clinical practice guidelines adds a dimension that informs stakeholders (including patients) on how an intervention impacts costs, health outcomes and provides a way to evaluate potential consequences of practice. for example, there is no standard or regulated time from amputation surgery for when a lower limb prosthetic device should be provided or intervention initiated, such as a consult with a prosthetist.29 however, a recent study analyzed the impact of providing a prosthesis earlier, within 0 to 3 months postamputation and demonstrated an overall cost savings.23 additionally, there is not a standard guideline to what type of device is appropriate based on patient presentation.5,33,34 future studies should compare selection and design of devices and include outcomes such as health utility and health-related quality of life. heor studies have the potential to inform clinical practice guidelines with the intention to optimize patient care and outcomes. the recently published mobility analysis of amputees (maat ii) aims to assist in clinical decision-making by presenting standard outcome measures of mobility and demonstrates that the presence of comorbidities does not preclude an individual from prosthetic mobility success.35 specific outcome measures are not standard of practice yet; however, the maat ii study is a start to standardize prosthetic decision-making by demonstrating that the incorporation of patient outcomes is critical to inform policy. the provision and use of a prosthesis is a critical component of a person’s rehabilitation after a lla as it is associated with a person’s ability to return to adls and reintegrate into social or work routines.17,36 the timing from amputation surgery to initial device provision has several potential influences including the patient’s age, income and rehabilitation setting.36 post-acute care typically occurs at home, an in-patient rehabilitation facility or skilled nursing facility, all which contribute to varying processes and therefore influence timing.36 gaps in our knowledge in spite of the growing number of potential prosthesis users, the increasing number of individuals with functional impairment, and of those who experience fall-related injuries in the us, research in heor among o&p is sparse. nationally, we lack the outcomes research, cost analyses and clinical practice guidelines needed to minimize acute health complications or emergency utilization, support patients’ functional mobility, and reduce costs associated with less-than-optimal patient outcomes. yet, the influence of o&p interventions on modifiable clinical outcomes, such as functional mobility or pain, are not well understood. there is a shortage of empirical outcomes research to https://doi.org/10.33137/cpoj.v4i2.35959 4 miller ta, wurdeman s, paul r, forthofer m. the value of health economics and outcomes research in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.8. https://doi.org/10.33137/cpoj.v4i2.35959 issn: 2561-987x the value of health economics and outcomes research miller et al. 2021 cpoj special s p e c ia l i s s u e demonstrate effectiveness and value of rehabilitation services for individuals with lla. informing perspective on the field with increasing pressure from payers for clinicians to efficiently and effectively provide o&p care, continued rwe to demonstrate and describe the value of o&p rehabilitation is crucial.17,24 as o&p technology continues to improve and provide benefit to all o&p device users, manufacturers should work collaboratively with key stakeholders and clinical sites to sponsor and disseminate rwe studies. such rwe studies would enhance findings from controlled clinical trials that are unable to capture the more broad-lived experiences of the naturally heterogeneous, diverse population of individuals with different o&p rehabilitation needs. rwe studies should include elements that focus on the enabling factors and perceived needs to further inform on how devices are accessed, utilized, and the subsequent associated outcomes in diverse populations. rwe is a more useful tool to engage physicians and patients following specific product launches.13 publishing observational studies of real-world data offers an important opportunity for researchers to provide stakeholders with data that reflects effectiveness in addition to existing evidence on efficacy and safety, particularly related to long-term outcomes. these types of studies can also include outcomes, such as patient-reported information and economic evidence (e.g. cost or utility data), which are growing in demand by payers and regulatory agencies. conclusion it is recommended that future studies consider the incorporation of data on additional enabling factors (e.g., income and education levels, social networks), perceived need factors (e.g., adherence to medication, use of prosthesis), and other modifiable risk factors (e.g., smoking). social determinants continue to influence the health outcomes of adults who require o&p care. illness that leads to amputation disproportionately affects persons with lower socioeconomic status, older patients, and persons who are racial/ethnic minorities, which results in disproportionately lower mobility and quality of life outcomes.37 as the demands increase in healthcare for value-based outcomes and rwe, it is imperative we continue to evaluate the impact of o&p rehabilitation services based on predisposing factors, enabling factors, and perceived need factors together. determining the value of o&p rehabilitation will help patients improve access to appropriate, high quality, and beneficial prosthetic componentry in a timely manner. if o&p services result in cost avoidance, better clinical outcomes, and improved quality of life for patients with lla or after a stroke, then we should continue to connect clinicians and researchers to inform administrative decision-making, improve coverage of services so all patients have equity in access and health outcomes. call to action there is a growing number of prosthesis and orthosis users, individuals with functional impairment, and those who experience fall-related injuries in the us. yet, research in heor among o&p struggles to keep pace. nationally, there is a need for more outcomes research, cost analyses and clinical practice guidelines to help minimize acute health complications or emergency utilization, support patients’ functional mobility, and reduce costs associated with less-than-optimal patient outcomes. the influence of o&p interventions on modifiable clinical outcomes, such as functional mobility or pain, needs a greater level of understanding. there is a need for more empirical outcomes research to demonstrate the effectiveness and value of rehabilitation services for individuals with functional impairment who require o&p devices. the first call to action recommended is for clinical researchers and health outcomes researchers (e.g. epidemiologists, economists) to join together to assess effectiveness of o&p devices on diverse populations. a greater understanding of effectiveness and rwe will improve access for patients to appropriate technology. a second call to action is for our professional bodies along with clinicians, patients and advocates to expand awareness of outcomes research. this includes the analysis of administrative databases, clinical databases, electronic health records, and more by researchers. 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j prosthetics orthot. 2019;31:37–42. doi: 10.1097/jpo.0000000000000227 16.kaluf b. provider perspective in the health care economics of lower-limb prosthetic rehabilitation. j prosthetics orthot. 2019;31:43–8. doi: 10.1097/jpo.0000000000000230 17.dobson a, el-gamil a, shimer m, davanzo je. economic value of prosthetic services among medicare beneficiaries: a claimsbased retrospective cohort study. mil med. 2016;181(2s):18–24. doi: 10.1186/s12984-018-0406-7 18.gerzeli s, torbica a, fattore g. cost utility analysis of knee prosthesis with complete microprocessor control (c-leg) compared with mechanical technology in trans-femoral amputees. eur j heal econ. 2009;10(1):47–55. doi: 10.1007/s10198-008-0102-9 19.glassman sd, carreon ly, shaffrey ci, polly dw, ondra sl, berven sh, et al. the costs and benefits of nonoperative management for adult scoliosis. spine. 2010;35(5):578–82. doi: 10.1097/brs.0b013e3181b0f2f8 20.gil j, schiff ap, pinzur ms. cost comparison: limb salvage versus amputation in diabetic patients with charcot foot. foot ankle int. 2013; doi: 10.1177/1071100713483116 21.edwards ds, phillip rd, bosanquet n, bull amj, clasper jc. what is the magnitude and long-term economic cost of care of the british military afghanistan amputee cohort? clin orthop relat res. 2015;473(9):2848–55. doi: 10.1007/s11999-015-4250-9 22.geidl w, knocke k, schupp w, pfeifer k. measuring stroke patients’ exercise preferences using a discrete choice experiment. neurol int. 2018;10:6993. doi: 10.4081/ni.2018.6993 23.miller ta, paul r, forthofer m, wurdeman sr. impact of time to receipt of prosthesis on total healthcare costs 12 months postamputation. am j phys med rehabil. 2020;99(11). doi: 10.1097/phm.0000000000001473 24.highsmith mj, kahle jt, lewandowski a, klenow td, orriola jj, miro rm, et al. economic evaluations of interventions for transtibial amputees: a scoping review of comparative studies. technol innov. 2016;18(2–3):85–98. doi:10.21300/18.23.2016.85 25.howard-wilsher s, irvine l, fan h, shakespeare t, suhrcke m, horton s, et al. systematic overview of economic evaluations of health-related rehabilitation. disabil health j. 2016;9(1):11–25. doi: 10.1016/j.dhjo.2015.08.009 26.schraner i, de jonge d, layton n, bringolf j, molenda a. using the icf in economic analyses of assistive technology systems: methodological implications of a user standpoint. disabil rehabil. 2008;30(12–13):916–26. doi: 10.1080/09638280701800293 27.anderson r. andersen and newman framework of health services utilization. j health soc behav. 1995;36:1–10. 28. krug e, cieza a. strengthening health systems to provide rehabilitation services. can j occup ther. 2017;84(2):72-3. doi: 10.23736/s1973-9087.17.04728-1 29.ülger ö, yıldırım şahan t, çelik se. a systematic literature review of physiotherapy and rehabilitation approaches to lower-limb amputation. physiother theory pract. 2018;34(11):821–34. 30.desveaux l, goldstein rs, mathur s, hassan a, devlin m, pauley t, et al. physical activity in adults with diabetes following prosthetic rehabilitation. can j diabetes. 2016;40(4):336–41. doi: 10.1016/j.jcjd.2016.02.003 https://doi.org/10.33137/cpoj.v4i2.35959 https://www-rand-org.proxy.bib.uottawa.ca/content/dam/rand/pubs/research_reports/rr2000/rr2096/rand_rr2096.pdf https://www-rand-org.proxy.bib.uottawa.ca/content/dam/rand/pubs/research_reports/rr2000/rr2096/rand_rr2096.pdf https://www-rand-org.proxy.bib.uottawa.ca/content/dam/rand/pubs/research_reports/rr2000/rr2096/rand_rr2096.pdf 6 miller ta, wurdeman s, paul r, forthofer m. the value of health economics and outcomes research in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.8. https://doi.org/10.33137/cpoj.v4i2.35959 issn: 2561-987x the value of health economics and outcomes research miller et al. 2021 cpoj special s p e c ia l i s s u e 31.wurdeman sr, stevens pm, campbell jh. mobility analysis of amputees (maat i): quality of life and satisfaction are strongly related to mobility for patients with a lower limb prosthesis. prosthet orthot int. 2018;42(5):498–503. doi: 10.1177/0309364617736089 32.miller ta, paul r, forthofer m, wurdeman sr. the role of earlier receipt of a lower limb prosthesis on emergency department utilization. pm&r. 2020;1-8. doi: 10.1002/pmrj.12504 33.stevens pm, rheinstein j, wurdeman sr. prosthetic foot selection for individuals with lower-limb amputation: a clinical practice guideline. j prosthetics orthot. 2018;30(4):175–80. doi: 10.1097/jpo.0000000000000181 34.broomhead p, clark k, dawes d, hale c, lambert a, quinlivan d, et al. evidence based clinical guidelines for the physiotherapy management of adults with lower limb prostheses, 2nd edition. 2nd ed. london: chartered society of physiotherapy; 2012. 1–68. 35.wurdeman sr, stevens pm, campbell jh. mobility analysis of amputees ii: comorbidities and mobility in lower limb prosthesis users. am j phys med rehabil. 2018;97:782–8. doi: 10.1097/phm.0000000000000967 36.roth e v., pezzin le, mcginley el, dillingham tr. prosthesis use and satisfaction among persons with dysvascular lower limb amputations across postacute care discharge settings. pm&r. 2014;6(12):1128–36. doi: 10.1016/j.pmrj.2014.05.024 37.sinha r, van den heuvel wja. a systematic literature review of quality of life in lower limb amputees. disabil rehabil. 2011;33(11):883–99. doi: 10.3109/09638288.2010.514646 authors scientific biography taavy miller, phd, cpo, is a research scientist within hanger’s department of clinical and scientific affairs. dr. miller has broad experience working as a certified orthotist/prosthetist at large hospital-based systems and in private practice as well as teaching p&o at the university level. dr. miller holds a doctoral degree in health services research with an emphasis in health economics and epidemiology. her research focuses on health equity, reducing disparities and improving access through the assessment of health outcomes and effectiveness using administrative, clinical and patient reported data. she has published several studies in peer-reviewed journals and presented abstracts at national and international conferences. shane wurdeman, phd, cp, is the director of clinical research within hanger’s department of clinical and scientific affairs. he entered the field of o&p as a technician before transitioning to working as an orthotist/prosthetist and finally into his role as a principal investigator. dr. wurdeman holds a bs in physics, an ms in prosthetics and orthotics, and a phd in biomechanics. he has coauthored more than 40 peer-reviewed manuscripts, published 3 book chapters, and presented more than 100 conference abstracts within the field of orthotic and prosthetic rehabilitation. he is a fellow with distinction of the american academy of orthotists and prosthetists, from whom he was recognized in 2020 with their prestigious academy research award. he currently serves as the research director for the american orthotic and prosthetic association and chair of the center for orthotic and prosthetic learning. he has been supported by private grants as well as government grants from the national institutes of health and department of defense. dr. rajib paul is an associate professor of biostatistics in the department of public health sciences and affiliate faculty of the school of data science at the university of north carolina charlotte. dr. paul has a broad spectrum of research interests. his areas of expertise include bayesian methods, big data analysis, spatial and spatiotemporal statistics, stochastic computation (markov chain monte carlo algorithms), and the applications of statistics to environmental, epidemiological (public and community health), and health policy-related problems. after graduating from the ohio state university with a ph.d. degree in statistics, he joined western michigan university (wmu) as a faculty in the department of statistics. he was an associate director and one of the founding members of the health data research analysis and mapping (hdream) center at the wmu. he has research experience in health disparities, environmental health, population health, and social and infectious disease epidemiology. his research focuses on identifying socioeconomic and geographic disparities in health outcomes and health service utilization. dr. paul worked on research projects funded by the national science foundation, robert wood johnson foundation, the centers for disease control and prevention, dhhs health resources and services administration (hrsa), and blue cross and blue shield of michigan. dr. melinda forthofer is a professor in the department of public health sciences in the college of health and human services at the university of north carolina charlotte. from 20162020, dr. forthofer served as department chair, leading the department through period of exponential growth through the addition of new programs and concentrations and recruitment of new faculty. prior to joining unc charlotte, dr. forthofer was on the faculty at the university of south florida (1996-2006) and at the university of south carolina (2006-2016). for over 20 years, her work has focused on social factors related to health behavior change in diverse community settings, often via community-based research. much of her current research is focused on the role of social factors in the promotion of health behaviors, particularly the role of social networks in physical activity. her research has been supported by over $29 million in extramurally funded research grants, via awards from several federal agencies (cdc, hrsa, nih), state health departments, local and national nonprofit organizations, and several private sector organizations. https://doi.org/10.33137/cpoj.v4i2.35959 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 2 2020 research article journeay w.s., marquez m.g., kowgier m. hemodialysis is not associated with pre-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation: a retrospective cohort study. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.2. https://doi.org/10.33137/cpoj.v3i2.34471 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v3i2.34471 1 journeay w.s., marquez m.g., kowgier m. hemodialysis is not associated with pre-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation: a retrospective cohort study. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.2. https://doi.org/10.33137/cpoj.v3i2.34471 research article hemodialysis is not associated with pre-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation: a retrospective cohort study journeay w.s.1,2 *, marquez m.g.3, kowgier m.4 1 providence healthcare – unity health toronto, toronto, on, canada. 2 division of physical medicine and rehabilitation, department of medicine, university of toronto, toronto, canada. 3 department of anatomy and cell biology, mcgill university, montreal, canada. 4 dalla lana school of public health, university of toronto, toronto, canada. introduction diabetes and peripheral arterial disease along with associated dysvascular complications are major risk factors for lower extremity amputation (lea).1-4 peripheral arterial disease and diabetes are associated with greater than 80% of lea in canada4,5 and recent data published by hussain et al.,6 concluded that diabetes-related amputations are on the rise. patients with comorbid diabetes and end-stage renal disease (esrd) receiving hemodialysis (hd) are at particularly high risk of lea.7-9 individuals with dysvascular limb loss that also receive hd often have additional comorbidity, mortality and poorer ambulatory outcomes.8,10-14 other common comorbidities in patients living with dysvascular amputation include open access volume 3, issue 2, article no.2. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: lower extremity amputation due to complications from peripheral vascular disease and/or diabetes are common and these patients often have multiple comorbidities. patients with endstage renal disease receiving hemodialysis (esrd/hd) are a particularly vulnerable group at risk for amputation. after lower extremity amputation (lea) surgery, many patients undergo post-operative inpatient rehabilitation to improve their pre-prosthetic functional independence. given the increased complexity of dysvascular patients living with esrd/hd compared to those without esrd/hd, the association of hd with pre-prosthetic inpatient functional outcomes warrants further study. objective: the objective of this study was to compare the pre-prosthetic functional outcomes and length of stay (los) among patients with recent dysvascular lea with and without esrd/hd. methodology: a retrospective cohort design was used to analyze a group of 167 patients with unilateral, dysvascular limb loss who were admitted to inpatient rehabilitation with 24 of these patients in the esrd/hd group. age, gender, amputation level, amputation side, length of stay (los), time since surgery, functional independence measure (fim) scores (admission and discharge), and charlson comorbidity index (cci) were collected. findings: there was no difference between patients with dysvascular amputation with and without esrd/hd in the association of functional outcomes or los in this cohort and rehabilitation model. the cci score was higher in the esrd/hd group. multivariate analysis indicated an inverse relationship with age and fim scores, where increased age was associated with lower total and motor fim at admission and discharge. there were no associations with fim change. age was positively associated with los. being female was inversely associated to motor fim scores at admission and discharge conclusion: among patients with recent dysvascular lea, esrd/hd is not associated with different functional outcomes or los in the pre-prosthetic inpatient rehabilitation setting. this suggests that despite added comorbidity that patients with esrd/hd may still benefit from inpatient rehabilitation to optimize pre-prosthetic function. article info received: july 13, 2020 accepted: august 30, 2020 published: september 4, 2020 citation journeay w.s., marquez m.g., kowgier m. hemodialysis is not associated with pre-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation: a retrospective cohort study. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.2. https://doi.org/10.33137/cpoj.v3i 2.34471 keywords dysvascular amputation, endstage renal disease, hemodialysis, inpatient rehabilitation, charlson comorbidity index * corresponding author: dr. w. shane journeay, phd, md, mph, frcpc, bc-occ med providence healthcare – unity health toronto, 3276 st clair avenue east, toronto on m1l 1w1 e-mail: shane.journeay@utoronto.ca orcid: https://orcid.org/0000-0001-6075-3176 https://doi.org/10.33137/cpoj.v3i2.34471 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i2.34471 https://doi.org/10.33137/cpoj.v3i2.34471 https://orcid.org/0000-0001-6075-3176 2 journeay w.s., marquez m.g., kowgier m. hemodialysis is not associated with pre-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation: a retrospective cohort study. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.2. https://doi.org/10.33137/cpoj.v3i2.34471 issn: 2561-987x hemodialysis and pre-prosthetic inpatient rehabilitation journeay et al. 2020 cpoj hypertension, diabetes, heart disease and peripheral arterial disease. data on the specific relationships between comorbidity and inpatient rehabilitation functional outcomes after lea are still emerging15,16 with relatively less published on the rehabilitation of patients needing hd.11,17 patients receiving hd tend to be medically complex and need to attend hd while also undergoing rehabilitation, which can potentially impact the course of an inpatient rehabilitation admission after lea. moreover, patients with esrd tend to have more advanced comorbid disease and frailty18 and therefore lea is often a significant medical event requiring post-operative rehabilitation.19 given the poor long-term outcomes of patients with dysvascular amputation receiving hd7,10,12,20 it remains important to determine the postoperative, inpatient functional outcomes and rehabilitations needs as many patients will need to achieve a functional status sufficient to return home.21 inpatient rehabilitation after lea is particularly beneficial as it is associated with fewer additional amputations, reduced mortality, a greater probability of receiving a prosthesis, and improved medical stability.22-24 regardless of one’s prosthetic candidacy, patients undergoing amputation have a number of post-operative rehabilitation needs including wound care, transfer training, wheelchair skills and contracture prevention which are needed to facilitate a safe discharge from a rehabilitation hospital. one commonly used measure of functional change in the inpatient rehabilitation setting is the functional independence measure (fim).25,26 previous work by arneja et al.11 demonstrated that patients with recent limb loss who were receiving hd had a longer length of stay (los) in rehabilitation and lower fim scores than patients who did not require hd. this retrospective study included prosthetic rehabilitation outcomes with fim scores reported at discharge from inpatient rehabilitation and at mean follow up of 13.8 months (3-31 months). they did not include a standardized index of comorbidity or admission fim scores. czyrny & merrill27 also compared 19 patients with lea with esrd receiving hd and 19 patients with peripheral vascular disease-related amputation not receiving hd. they studied ambulatory outcomes in addition to fim at admission, discharge and fim change. they noted an increased burden of comorbidity in the esrd group but found no differences between the two groups in functional outcomes at discharge which included ambulation with a prosthesis. we aimed to compare the pre-prosthetic functional outcomes and los among patients with dysvascular lea with and without esrd/ hd. this work adds to the literature by using the charlson comorbidity index (cci) in this population and capturing both the admission and discharge fim for pre-prosthetic, post-operative inpatient rehabilitation in patients with recent lea. methodology this was a retrospective cohort study and was approved by the research ethics board of providence healthcare and closed by the unity health toronto research ethics board. all patients with a lea that were discharged from our rehabilitation hospital between january 1, 2014 and march 30, 2018 were identified and their medical records were reviewed. inclusion criteria for the study consisted of those with a recent unilateral, transfemoral (tf) or transtibial (tt) amputation. only patients with amputations due to a dysvascular etiology were included, and those due to trauma, cancer, or other reasons were excluded. those patients receiving hd who also met the inclusion criteria were included. inclusion and exclusion criteria were developed to establish a uniform data set of the most common reason for admission to post-amputation inpatient rehabilitation (dysvascular amputation). patients who met inclusion criteria but had an incomplete data set were excluded. all data retrieved from medical records came from both physical charts and electronic files utilized by health information management at the hospital. the rehabilitation model at this institution involved postoperative interdisciplinary rehabilitation including physiotherapy, occupational therapy, nursing, wound care, and physiatry consultation. patients did not receive hd on-site but were able to travel to their hd treatments at outside facilities three days per week. the focus of rehabilitation for these patients was solely pre-prosthetic rehabilitation which includes, but is not limited to: wound care, standing tolerance, contracture prevention, adls, transfers, and wheelchair skills. patients were discharged home after preprosthetic rehabilitation and then were revisited regarding prosthetic candidacy and gait training at a later date. data that was extracted from the medical records included age, sex, amputation level, amputation side, surgery date, los in inpatient rehabilitation, fim scores at admission and discharge,25,26 and cci total score.28,29 the authors are aware that the cci was initially used as an epidemiological tool to predict mortality in patients admitted to hospital. however, we have selected the cci as a standardized method in which to catalogue comorbidities and have used it in previous published work.15 each patient was reviewed using the cci and assigned points for the individual conditions, then given a total score. these scores were based on information present upon their admission and any past medical history that was documented in the chart. the time since surgery was also recorded by calculating the number of days between the surgery date and the admission date to inpatient rehabilitation. los in rehabilitation was calculated from admission date to discharge date. total fim, and total motor fim, information was retrieved from admission and discharge data. we included motor fim because in the pre-prosthetic phase of rehabilitation the motor fim scores would reflect acquisition https://doi.org/10.33137/cpoj.v3i2.34471 3 journeay w.s., marquez m.g., kowgier m. hemodialysis is not associated with pre-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation: a retrospective cohort study. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.2. https://doi.org/10.33137/cpoj.v3i2.34471 issn: 2561-987x hemodialysis and pre-prosthetic inpatient rehabilitation journeay et al. 2020 cpoj of independence with transfers and wheelchair mobility as this study did not examine prosthetic gait outcomes. statistical methods continuous variables were summarized by observed means with standard deviation (sd) and categorical variables were summarized by frequency counts (percentages). univariate and multivariate linear regression analyses were used to investigate the effect of hd on each of the outcomes of total and motor fim, at both admission and discharge separately (i.e., cross-sectional effects), as well as los. to investigate the longitudinal effects, changes between discharge and admission were computed for both total (fim total change) and motor fim (motor fim change). univariate and multivariate linear regression analyses were used to investigate the effect of hd on each of the outcomes of fim total change and motor fim change. multiple regression analysis adjusted for clinically relevant variables including age, sex, amputation level, amputation side, and the charlson comorbidity index. data was analyzed using the r statistical software (version 3.5.1). results all patients admitted with a diagnosis of lea from january 1, 2014 to march 30, 2018 were identified by our medical records team for a total of 382 records. three patients were excluded due to death prior to discharge. four patients were excluded due to incomplete admission to discharge data sets. two hundred and eight patients were excluded by not meeting inclusion criteria such as: etiology of amputation (i.e. not dysvascular), had bilateral amputations, or were not tt or tf level amputations (i.e. only forefoot or toe amputation), or were not admitted post-operatively but rather for other reasons such as gait training or other medical conditions. there was a total of 167 patients with dysvascular amputation meeting the inclusion criteria with 24 of these patients receiving hd (table 1). a descriptive comparison of the dysvascular and dysvascular with esrd/hd groups showed a significant difference between the cci scores [4.7 (sd=1.7) vs 8.0 (sd=1.7)], p<0.001. table 1 presents further descriptive data, and a demographic comparison of the dysvascular only and hd groups. after univariate analysis, age was negatively associated with both total fim at admission (beta -0.58, ci [ (-0.78) (-0.39)], p<0.001) and at discharge (beta -0.48, ci [ (-0.66) (-0.29)] p<0.001). age was also associated with motor fim at admission (beta -0.44, ci [ (-0.60) (-0.28)] p<0.001) and at discharge (beta -0.34, ci [ (-0.49) (-0.19)] p<0.001). sex was also associated with motor fim at admission (beta -4.13, ci [ (-7.99) (-0.27)], p=0.038) and discharge (beta 4.28, ci [ (-7.83) (-0.73)], p=0.019). age showed a relationship with los that was nearly statistically significant in the univariate analysis (beta 0.25, ci [ (-0.01) (0.50)], p=0.066) and was therefore carried forward in the multivariate analysis. there were no associations between the hd vs no hd. the remaining univariate analyses are presented in table 2. the factors that showed an association after the univariate analysis or were clinically relevant were then adjusted using multivariate analysis. greater age was shown to be associated with lower total fim scores at admission (estimate -0.59, se 0.10, p<0.001) and discharge (estimate -0.49, se 0.10, p<0.001). age was associated with motor fim at admission (estimate -0.46, se 0.08, p<0.001) and discharge (estimate -0.33, se 0.08, p<0.001). being female was inversely associated to motor fim scores at admission (estimate -4.50, se 1.84, p=0.016) and discharge (estimate -4.21, se 1.75, p=0.017). age was positively associated with los (estimate 0.28, se 0.14, p=0.044). table 3 includes remaining data from multivariate analysis. table 1: cohort description. *p<0.05. discussion the objective of this study was to examine the association of hd with pre-prosthetic inpatient rehabilitation outcomes and los in a cohort of patients with dysvascular lea. notable findings from this study included: 1. both groups of patients were similar in the amputation characteristics however patients with hd had a higher cci indicating a greater burden of comorbidity 2. despite a higher cci in the hd group there was no difference in fim scores or los. 3. age and sex were associated with total and motor fim at admission and discharge and age was associated with los. dysvascular cohort no hemodialysis n=143 hemodialysis n=24 age (years) 67.7 (sd=11.1) 64 (sd=7.4) sex m 95(66%) 18(75%) f 48(33%) 6(25%) amputation level transfemoral 59 (41%) 9 (38%) transtibial 84 (59%) 15 (62%) amputation side left 69 (48) 12 (50%) right 74 (52) 12 (50%) time since surgery to admission (days) 15.2 (sd=13.8) 17.3 (sd=10.6) length of stay in rehabilitation (days) 33.9 (sd=18.6) 32.4 (sd=17.2) charlson comorbidity index 4.7 (sd=1.7) 8.0 (sd=1.7)* fim scores total admission 72.6 (sd=14.4) 73.2 (sd=13.5) total discharge 97.5 (sd=14.3) 97.2 (sd=11.1) motor total admission 42.7 (sd=12.0) 42.3 (sd=12.6) motor total discharge 66.9 (sd=11.4) 65.8 (sd=9.5) efficiency 0.9 (sd=0.5) 0.9 (sd=0.6) https://doi.org/10.33137/cpoj.v3i2.34471 4 journeay w.s., marquez m.g., kowgier m. hemodialysis is not associated with pre-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation: a retrospective cohort study. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.2. https://doi.org/10.33137/cpoj.v3i2.34471 issn: 2561-987x hemodialysis and pre-prosthetic inpatient rehabilitation journeay et al. 2020 cpoj t a b le 2 : a : u n iv a ri a te a n a ly s is – f im t o ta l a d m is s io n a n d d is c h a rg e , f im c h a n g e , l o s , *p < 0 .0 5 . b : u n iv a ri a te a n a ly s is – f im m o to r a d m is s io n a n d d is c h a rg e , f im m o to r c h a n g e . f im t o ta l a d m is s io n f im t o ta l d is c h a rg e f im t o ta l c h a n g e l e n g th o f s ta y ( l o s ) a b e ta c i p v a lu e b e ta c i p v a lu e b e ta c i p v a lu e b e ta c i p v a lu e s e x , f e m a le v s m a le -3 .5 0 [ (8 .1 0 ) (1 .1 ) ] 0 .1 3 8 -3 .9 9 [ (8 .4 6 ) (0 .4 7 ) ] 0 .0 8 1 -0 .5 0 [ (3 .7 8 ) (2 .7 9 ) ] 0 .7 6 7 -0 .6 8 [ (6 .6 6 ) (5 .2 9 ) ] 0 .8 2 3 a m p s id e , l e ft v s r ig h t -0 .5 8 [ (4 .9 1 ) (3 .7 5 ) ] 0 .7 9 3 -2 .1 9 [ (6 .4 0 ) (2 .0 1 ) ] 0 .3 0 8 -1 .6 1 [ (4 .6 8 ) (1 .4 5 ) ] 0 .3 0 4 1 .6 4 [ (3 .9 4 ) (7 .2 3 ) ] 0 .5 6 5 a m p l e v e l, t f v s t t -2 .6 3 [ (7 .0 2 ) (1 .7 7 ) ] 0 .2 4 3 -2 .2 8 [ (6 .5 6 ) (2 .0 0 ) ] 0 .2 9 8 -0 .3 5 [ (2 .7 8 ) (3 .4 7 ) ] 0 .8 2 8 -3 .3 5 [ (9 .0 2 ) (2 .3 2 ) ] 0 .2 4 9 a g e -0 .5 8 [ (0 .7 8 ) (0 .3 9 ) ] 0 * -0 .4 8 [ (0 .6 6 ) (0 .2 9 ) ] 0 * -0 .0 9 [ (0 .0 5 ) (0 .2 4 ) ] 0 .2 1 3 0 .2 5 [ (0 .0 1 ) (0 .5 0 ) ] 0 .0 6 6 h d v s n o h d -0 .5 2 [ (6 .7 0 ) (5 .6 5 ) ] 0 .8 6 8 0 .3 0 [ (5 .7 1 ) (6 .3 1 ) ] 0 .9 2 2 0 .8 3 [ (3 .5 5 ) (5 .2 0 ) ] 0 .7 1 2 1 .4 9 [ (6 .4 8 ) (9 .4 5 ) ] 0 .7 1 5 c h a rl s o n c o m o rb id it y i n d e x -0 .6 5 [ (1 .7 0 ) (0 .4 0 ) ] 0 .2 2 7 -0 .6 1 [ (1 .6 3 ( 0 .4 1 ) ] 0 .2 4 5 0 .0 4 [ (0 .7 0 ) (0 .7 9 ) ] 0 .9 1 3 0 .2 4 [ (1 .1 1 ) (1 .6 0 ) ] 0 .7 2 5 f im m o to r a d m is s io n f im m o to r d is c h a rg e f im m o to r c h a n g e b b e ta c i p v a lu e b e ta c i p v a lu e b e ta c i p v a lu e s e x , f e m a le v s m a le -4 .1 3 [ (7 .9 9 ) (0 .2 7 ) ] 0 .0 3 8 * -4 .2 8 [ (7 .8 3 ) (0 .7 3 ) ] 0 .0 1 9 * -0 .1 5 [ (3 .2 1 ) (2 .9 1 ) ] 0 .9 2 4 a m p s id e , l e ft v s r ig h t 0 .5 7 [ (3 .1 0 ) (4 .2 3 ) ] 0 .7 6 2 -1 .4 9 [ (4 .8 6 ) (1 .8 8 ) ] 0 .3 8 8 -2 .0 5 [ (4 .9 0 ) (0 .8 0 ) ] 0 .1 6 0 a m p l e v e l, t f v s t t -2 .8 3 [ (6 .0 9 ) (1 .3 3 ) ] 0 .2 1 0 -2 .8 8 [ (6 .2 9 ) (0 .5 3 ) ] 0 .1 0 0 -0 .5 0 [ (3 .4 2 ) (2 .4 2 ) ] 0 .7 3 7 a g e -0 .4 4 [ (0 .6 0 ) (0 .2 8 ) ] 0 * -0 .3 4 [ (0 .4 9 ) (0 .1 9 ) ] 0 * 0 .1 1 [ (0 .0 3 ) (0 .2 4 ) ] 0 .1 2 0 h d v s n o h d 0 .4 1 [ (4 .8 0 ) (5 .6 3 ) ] 0 .8 7 6 1 .1 9 [ (3 .6 2 ) (6 .0 0 ) ] 0 .6 2 9 0 .7 7 [ (3 .3 1 ) (4 .8 6 ) ] 0 .7 1 1 c h a rl s o n c o m o rb id it y i n d e x -0 .6 0 [ (1 .4 9 ) (0 .2 8 ) ] 0 .1 8 3 -0 .6 7 [ (1 .4 9 ( 0 .1 4 ) ] 0 .1 0 7 -0 .0 7 [ (0 .7 7 ( 0 .6 3 ) ] 0 .8 4 7 t a b le 3 : a : m u lt iv a ri a te a n a ly s is – f im t o ta l a d m is s io n a n d d is c h a rg e , f im c h a n g e , l o s , *p < 0 .0 5 . b : m u lt iv a ri a te a n a ly s is – f im m o to r a d m is s io n a n d d is c h a rg e , f im c h a n g e . f im t o ta l a d m is s io n f im t o ta l d is c h a rg e f im t o ta l c h a n g e l e n g th o f s ta y ( l o s ) a e s ti m a te ( s e ) tv a lu e p v a lu e e s ti m a te ( s e ) tv a lu e p -v a lu e e s ti m a te ( s e ) tv a lu e p v a lu e e s ti m a te (s e ) tv a lu e p v a lu e in te rc e p t 1 1 7 .6 5 ( 8 .0 7 ) 1 4 .5 7 0 1 3 5 .2 5 ( 8 .0 7 ) 1 6 .7 6 0 .0 0 0 1 7 .6 1 ( 6 .3 8 ) 2 .7 6 0 .0 0 6 1 0 .0 6 ( 1 1 .4 9 ) 0 .8 8 0 .3 8 2 s e x , f e m a le v s m a le -3 .7 2 ( 2 .1 7 ) -1 .7 1 0 .0 8 8 -4 .0 0 ( 2 .1 7 ) -1 .8 5 0 .0 6 7 -0 .2 8 ( 1 .7 1 ) -0 .1 6 0 .8 7 0 -0 .4 2 ( 3 .0 8 ) -0 .1 4 0 .8 9 2 a m p s id e , l e ft v s r ig h t 1 .0 7 ( 2 .0 3 ) 0 .5 3 0 .6 0 0 -0 .7 2 ( 2 .0 3 ) -0 .3 5 0 .7 2 4 -1 .7 9 ( 1 .6 1 ) -1 .1 1 0 .2 6 8 1 .1 9 ( 2 .8 9 ) 0 .4 1 0 .6 8 0 a m p l e v e l, t f v s t t 0 .8 6 ( 2 .1 1 ) 0 .4 1 0 .6 8 5 0 .6 9 ( 2 .1 1 ) 0 .3 3 0 .7 4 3 -0 .1 6 ( 1 .6 7 ) -0 .1 0 0 .9 2 2 -4 .9 5 ( 3 .0 0 ) -1 .6 5 0 .1 0 0 a g e -0 .5 9 ( 0 .1 0 ) -6 .0 2 0 * -0 .4 9 ( 0 .1 0 ) -4 .9 9 0 * 0 .1 0 ( 0 .0 8 ) 1 .3 0 0 .1 9 6 0 .2 8 ( 0 .1 4 ) 2 .0 3 0 .0 4 4 * h d v s n o h d -0 .9 4 ( 3 .5 1 ) -0 .2 7 0 .7 9 0 -0 .0 6 ( 3 .5 1 ) 0 .0 2 0 .9 8 7 0 .8 8 ( 2 .7 8 ) 0 .3 2 0 .7 5 1 3 .0 6 ( 5 .0 0 ) 0 .6 1 0 .5 4 1 c h a rl s o n c o m o rb id it y i n d e x -0 .8 6 ( 0 .6 0 ) -1 .4 3 0 .1 5 4 -0 .7 3 ( 0 .6 0 ) -1 .2 2 0 .2 2 4 0 .1 3 ( 0 .4 7 ) 0 .2 7 0 .7 8 9 0 .7 1 ( 0 .8 5 ) 0 .8 3 0 .4 0 7 f im m o to r a d m is s io n f im m o to r d is c h a rg e f im m o to r c h a n g e b e s ti m a te ( s e ) tv a lu e p v a lu e e s ti m a te ( s e ) tv a lu e p -v a lu e e s ti m a te ( s e ) tv a lu e p v a lu e in te rc e p t 7 7 .0 3 ( 6 .8 6 ) 1 1 .2 2 0 9 4 .0 4 ( 6 .5 1 ) 1 4 .4 5 0 1 7 .0 1 ( 5 .9 1 ) 2 .8 8 0 .0 0 5 s e x , f e m a le v s m a le -4 .5 0 ( 1 .8 4 ) -2 .4 4 0 .0 1 6 * -4 .2 1 ( 1 .7 5 ) -2 .4 1 0 .0 1 7 * 0 .2 8 ( 1 .5 9 ) 0 .1 8 0 .8 5 8 a m p s id e , l e ft v s r ig h t 2 .0 6 ( 1 .7 3 ) 1 .1 9 0 .2 3 4 -0 .3 4 ( 1 .6 4 ) -0 .2 1 0 .8 3 6 -2 .4 0 ( 1 .4 9 ) -1 .6 2 0 .1 0 8 a m p l e v e l, t f v s t t 0 .4 9 ( 1 .7 9 ) 0 .2 8 0 .7 8 4 -0 .6 4 ( 1 .7 0 ) -0 .3 8 0 .7 0 6 -1 .1 4 ( 1 .5 4 ) -0 .7 4 0 .4 6 3 a g e -0 .4 6 ( 0 .0 8 ) -5 .5 9 0 * -0 .3 3 ( 0 .0 8 ) -4 .2 5 0 * 0 .1 3 ( 0 .0 7 ) 1 .8 2 0 .0 7 1 h d v s n o h d 0 .3 5 ( 2 .9 9 ) 0 .1 2 0 .9 0 6 0 .5 0 ( 2 .8 3 ) 0 .1 8 0 .8 5 9 0 .1 5 ( 2 .5 7 ) 0 .0 6 0 .9 5 4 c h a rl s o n c o m o rb id it y i n d e x -0 .6 4 ( 0 .5 1 ) -1 .2 7 0 .2 0 6 -0 .6 8 ( 0 .4 8 ) -1 .4 2 0 .1 5 8 -0 .0 4 ( 0 .4 4 ) -0 .0 9 0 .9 3 2 https://doi.org/10.33137/cpoj.v3i2.34471 5 journeay w.s., marquez m.g., kowgier m. hemodialysis is not associated with pre-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation: a retrospective cohort study. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.2. https://doi.org/10.33137/cpoj.v3i2.34471 issn: 2561-987x hemodialysis and pre-prosthetic inpatient rehabilitation journeay et al. 2020 cpoj this study is unique in that it examines the cci in patients with dysvascular limb loss with and without esrd/hd and the association with inpatient pre-prosthetic functional outcomes and los. prior work would suggest that patients living with esrd/hd have greater medical complexity and an increased number of comorbidities.11,14,20 however, our data add to the literature by reporting the cci in an inpatient rehabilitation cohort. our previous work examined the cci and its components in a dysvascular group of patients with limb loss but excluded patients receiving hd.15 given the literature suggesting a number of poorer outcomes after lea we sought to compare this group to patients without esrd/hd in the inpatient rehabilitation setting. while the cci was higher in the hd group, we found no associations with fim or los. although speculative, it is possible that increased comorbidity may be associated with poorer ambulatory outcomes, but is not associated with shortduration pre-prosthetic functional gains. the literature would suggest that patients with dysvascular lea who also have esrd/hd have much higher mortality rates than those without hd and very low rates of ambulation with a prosthesis. one study reported that <10% of patients receiving hd retained their ability to ambulate at 1-year after amputation.12 it has also been shown that in patients with dysvascular lea that those who are ambulatory have higher survival than those who do not ambulate.12,14 while inpatient rehabilitation has been shown to increase the likelihood of receiving a prosthesis in those with limb loss,22 it remains unknown whether this is true in the esrd/hd population. therefore, after amputation surgery these patients may still benefit from inpatient rehabilitation to maintain their pre-prosthetic independence. specifically, in patients living with esrd/hd where survival and ambulatory outcomes are poor, post-operative inpatient rehabilitation can allow for medical monitoring, transfer and wheelchair training and assessment of adl prior to discharge from the inpatient rehabilitation hospital setting.19 our data would suggest that despite greater comorbidity in patients with dysvascular amputation with esrd/hd, there is no difference in total and motor fim or los compared to patients without esrd/hd for pre-prosthetic inpatient rehabilitation. a study by arneja et al.11 examined functional outcomes of patients with lea receiving hd and those without hd. in their study only discharge fim scores were included, while our study contained both admission and discharge fim. additionally, their study examined various comorbidities but did not use an established index such as the cci. overall, in our study the total cci score did not show association with pre-prosthetic functional outcomes in this cohort after multivariate analysis. fim changes and scores in our cohort indicate the acquisition of independence with adl, transfers and wheelchair mobility as this study did not examine prosthetic gait outcomes. these patients are medically complex and admitted for preprosthetic rehabilitation, so their functional change as reflected by the fim would be different than studies that have included ambulation as an outcome. given the increased comorbidities and frailty in the esrd/hd group, this data suggests that patients undergoing dysvascular amputation can still derive benefit from pre-prosthetic rehabilitation even if they are receiving hd. additionally, there was no association of comorbidity with los suggesting that despite an increased burden of comorbidity and attendance at hd during rehabilitation, these patients can achieve a pre-prosthetic functional level that supports a safe discharge in a similar amount of time to non-esrd/hd patients with recent lea while admitted to inpatient rehabilitation. age was a factor that was found to have an association with total and motor fim at both admission and discharge, with advanced age associated with lower fim scores. there was not an association with fim change, however, suggesting that despite lower fim at admission and discharge the rate of change during the inpatient stay was not associated with age. there are prior studies that support the notion that advanced age is associated with poorer functional outcomes in patients with limb loss.30,31 however, another report by chopra et al.14 did not indicate an association between greater age and poorer ambulatory rates, which they attributed to their cohort size. it is also well established that age is a powerful prognostic factor in gait retraining after amputation.32 in other work, age was also associated with decreased survival post amputation in patients receiving hd.12 thus, while age was associated with fim at the time of admission and discharge, this group of patients did derive benefit from pre-prosthetic inpatient rehabilitation regardless of their future prosthetic candidacy. additionally, age was associated with los, suggesting that the older, dysvascular patient with recent lea may require additional time in hospital to reach pre-prosthetic functional independence. limitations while prior reports indicated that esrd/hd is associated with increased mortality and lower ambulatory function after dysvascular amputation,12,14,33 this cohort admitted for preprosthetic rehabilitation was not impacted. this suggests that patients with dysvascular lea admitted postoperatively and who may never be prosthetic candidates may still benefit from inpatient rehabilitation to recover from surgery and restore independence prior to discharge even with esrd/hd. the cci reflects specific medical comorbidities however other factors may also play a role in rehabilitation after limb loss including the condition of the contralateral limb, visual impairments, delayed wound healing and mental health status, which could be explored in future studies. furthermore, this cohort represents one post-amputation care model in canada and therefore the https://doi.org/10.33137/cpoj.v3i2.34471 6 journeay w.s., marquez m.g., kowgier m. hemodialysis is not associated with pre-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation: a retrospective cohort study. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.2. https://doi.org/10.33137/cpoj.v3i2.34471 issn: 2561-987x hemodialysis and pre-prosthetic inpatient rehabilitation journeay et al. 2020 cpoj results may not be directly generalized to other forms of rehabilitation services in different centers. conclusion we conducted this study to examine the role of esrd/hd in pre-prosthetic inpatient rehabilitation functional outcomes and los in a cohort of dysvascular patients with recent lower extremity amputation. esrd/hd was not associated with poorer fim scores or los. in keeping with previously published work, we did find association with age and the admission and discharge total fim, motor fim and los. these data suggest that despite the medical complexity, higher mortality and poorer prognosis for ambulation after lea in patients living with esrd/hd, they have a similar pre-prosthetic, inpatient rehabilitation functional benefit as dysvascular patients who not have esrd/hd. acknowledgements the authors would like to acknowledge the staff in the health information management office at providence healthcare for their support and assistance with this project. declaration of conflicting interests the authors have no conflicts of interest to declare. author contribution w. shane journeay: conceived the study and design, data interpretation and led the manuscript writing. michelle g. marquez: data collection, data interpretation, literature review and assisted in manuscript writing. matthew kowgier: assisted in study design, led statistical analysis and contributed to manuscript development sources of support michelle g. marquez received a providence healthcare student research stipend. ethical approval this was a retrospective cohort study and was approved by the research ethics board of providence healthcare and closed by the unity health toronto research ethics board. references 1.schofield cj, libby g, brennan gm, macalpine rr, morris ad, leese gp. mortality and hospitalization in patients after amputation: a comparison 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amputees. arch phys med rehabil. 2003; 84: 803-811. doi:10.1016/s0003-9993(02)04952-3 31.covinsky ke, palmer rm, fortinsky rh, counsell sr, stewart al, kresevic d, et al. loss of independence in activities of daily living in older adults hospitalized with medical illnesses: increased vulnerability with age. j am geriatr soc. 2003; 51: 451-458. doi: 10.1046/j.1532-5415.2003.51152.x 32.traballesi m, brunelli s, pratesi l, pulcini m, angioni c, paolucci s. prognostic factors in rehabilitation of above knee amputees for vascular diseases. disabil rehabil. 1998; 20(10):380‐384. doi:10.3109/09638289809166097 33.nehler mr, coll jr, hiatt wr, regensteiner jg, schnickel gt, klenke wa, et al. functional outcome in a contemporary series of major lower extremity amputations. j vasc surg. 2003; 38(1):7-14. doi:10.1016/s0741-5214(03)00092-2 https://doi.org/10.33137/cpoj.v3i2.34471 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 issn: 2561-987x volume 2, issue 2 2019 (online) r e s e a r c h a r t i c l e all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). https://doi.org/10.33137/cpoj.v2i2.32955 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation 1 open access gait characteristics of transtibial amputees volume 2, issue 2, article no.1, 2019 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index research article gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees pröbsting e1*, bellmann m1, schmalz t2, hahn a1 1 clinical research & services / biomechanics, ottobock se & co. kgaa, hermann-rein-straße 2a, 37075 göttingen, germany. 2 clinical research & services, ottobock healthcare products gmbh, brehmstraße 16, 1110 vienna, austria. abstract study design: retrospective analysis background: the gait characteristics of transtibial amputees (tts) have been described many times. in general, the literature reported nearly consistent results for the kinematic and kinetic parameters of the prosthetic side. however, the literature revealed inconsistent findings on kinetic parameters for determining the risk of developing knee osteoarthritis, such as the peak knee adduction moment, knee flexion moment and vertical ground reaction forces. objectives: the objective of our study was to describe the sagittal kinetic and kinematic gait characteristics of the ankle and residual knee joint of the prosthetic limb and the knee loading parameters of the sound side of unilateral tts. this specific consideration may contribute to resolving the controversy of these parameters in the literature. methods: we analysed our database containing gait analyses from 53 unilateral tts and compared data to a control group (cg), also taken from our database. the sagittal kinetic and kinematic gait characteristics of the ankle and residual knee joint of the prosthetic limb, and selected knee loading parameters of the sound side (the peak knee adduction moment, knee flexion moment and vertical ground reaction forces) were evaluated. beside these parameters we reported typical spatiotemporal gait parameters as gait velocity, step length, step length asymmetry, stance phase duration and asymmetry of stance phase duration. results: the tts walked slower and more asymmetrically than the cg. the kinematic pattern of the prosthetic ankle differed from that found in the cg. the largest difference was observed for the range of motion of the plantarflexion at push-off, which was significantly reduced for the prosthetic foot. the residual knee joint was generally affected with respect to decreased moments and reduced knee flexion during stance phase. the peaks of the vertical ground reaction forces and knee adduction moments showed no differences between the sound side of amputees and the cg. the peak knee flexion moment at midstance was significantly reduced for the sound side of amputees in comparison with the cg. conclusion: the biomechanical data measured for the prosthetic side in a cohort of 53 unilateral tt amputees conformed with the literature. the parameters determining the risk of developing knee osteoarthritis investigated in our retrospective analysis were not increased on the sound side in comparison with non-amputees. we deem it reasonable to assume that an appropriate prosthesis will reduce the likelihood of overloading the knee on the sound side during normal walking. citation pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.3 2955. keywords prosthesis, transtibial amputees, gait analysis, kinematic, kinetic, amputation, gait velocity, step length, gait asymmetry *corresponding author dipl.-ing (fh) eva pröbsting, clinical research & services / biomechanics, ottobock se & co. kgaa, hermann-rein-straße 2a, 37075 göttingen, germany. orcid: https://orcid.org/0000-0002-6349-2992 e-mail: eva.proebsting@ottobock.de doi: https://doi.org/10.33137/cpoj.v2i2.32955 article info received: august 6, 2019 accepted: january 10, 2020 published: january 15, 2020 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v2i2.32955 https://doi.org/10.33137/cpoj.v2i2.32955 https://orcid.org/0000-0002-6349-2992 file:///d:/cpoj%20submitted%20articles/accepted-completed/27-twenty%20seven%20article-cpoj-27-17a-2019-ottobock/proof-read/eva.proebsting@ottobock.de https://doi.org/10.33137/cpoj.v2i2.32955 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 2 cpoj pröbsting et al. 2019 gait characteristics of transtibial amputees introduction the gait characteristics of a transtibial amputee (tt) with a prosthesis significantly deviate from normal gait patterns.1,2 literature primarily analysed the effect of components, weight distributions or sockets, typically for a small number of patients.1,2 in general, from all of these studies, it can be concluded that tt amputees walk with slower velocity,3,4 shorter steps3,4 and longer stance duration on the sound limb5 compared to non-amputees. beside these temporalspatial parameters the results of kinetic and kinematic parameters enable a more detailed evaluation for the gait of tts. research studies3-18 reporting such findings for tts in comparison to nonamputees were summarized in table 1. most kinematic analyses of the prosthetic side reported a reduced range of plantarflexion in late stance and early swing5,7,16 in tts in comparison with non-amputees. furthermore, knee flexion was altered on the prosthetic side. knee flexion was reduced during stance phase4,5,6,9,11,16 and some studies showed a reduced peak knee flexion angle during swing.5,16 the kinematic pattern of the sound limb in tts appeared to be comparable to that of non-amputees.7 kinetic analyses of the prosthetic side consistently reported a lower external dorsiflexion moment in late stance with the prosthetic foot as compared to nonamputees.3,7 furthermore, the knee joint on the affected side showed a markedly reduced external flexion moment during midstance.4, 9 however, literature revealed inconsistent results with respect to kinetic compensatory adaptations on the sound side, specifically the peak knee adduction moment, knee flexion moment and vertical ground reaction forces. reports on the knee adduction moments on the sound side were conflicting: some studies showed no differences,12,16,17 others reported increases13,18 by trend, and a few studies14,15 found a reduction in comparison to controls. a similar controversy could be found for the comparison of the sound side knee flexion moments at midstance. a few studies showed a significant increase on the sound side in comparison to the controls8,14 others reported no differences7,9,17 or a decrease by trend.16 both parameters knee flexion and adduction moment refer to knee loading parameters influencing the risk of developing knee osteoarthritis. the relevance of the external knee adduction moment regarding the development of knee joint degeneration in the general population19 was highlighted. particularly, the first peak of the external knee adduction moment during stance has been associated with the severity of knee osteoarthritis.20,21 furthermore, the peak external knee flexion moment during midstance was considered as another predictor of knee loading22 and the first peak of the vertical ground reaction force was also increased for patients with knee osteoarthritis.20 the latter also showed diverging results for the sound side of tts in the literature: a significantly increased first peak on the sound side in comparison to healthy controls was reported in two studies.10,13 some studies showed a statistically nonsignificant increase,11,14,15,17 while other studies showed no differences at all.6, 7 as the investigations cited did not show consistent results, the described higher prevalence of knee osteoarthritis on the sound side in tts21 could not be explained with certainty to be caused by higher loads on this knee. different studies showed that the parameters on the sound side are mainly influenced by the prosthesis13,14,23 therefore the prosthetic side should also be analysed to evaluate compensatory adaptations on the sound side. in the present study we retrospectively analysed the tt population from our database including a large sample size to generate a representative cross section of this cohort and compared it to able-bodied individuals. the objective of our study was to compare the gait characteristics regarding the sagittal kinetic and kinematic parameters of the ankle and knee joints of the prosthetic limb for a large sample of unilateral tts. additionally, we have also examined the knee loading parameters on the sound side as indicators for determining the risk of developing knee osteoarthritis. this specific consideration may contribute to resolving the controversy of these parameters in the literature. methodology data collection gait analyses with amputees have been performed in the ottobock gait lab in göttingen since 2002, a vicon system has been available and only data obtained from this system were analysed retrospectively for this study. from 2002 to 2013, the experimental setup consisted of a 6 mx camera motion capture system (120 hz; vicon, oxford metrics, uk) and from 2013 onwards of a 12bonita camera motion capture system (200 hz; vicon, oxford metrics, yarnton, uk). two force plates (400 hz; kistler 9287a, winterthur, ch) were positioned in the centre of the 12-metre walkway for measuring the bilateral ground reaction forces during one gait cycle. both systems were synchronised, they started simultaneously via a light triggered photo cell. each subject conducted 8 to 15 single measurements of walking trials. the database included 279 amputees of different amputation levels with 5594 different measurement situations. we identified one characteristic session for each tt with the following inclusion criteria: -unilaterally amputated -adults > 18 years -no additional health impairment -walking with their self-selected velocity on level ground -prosthesis with a commercially available foot -prosthesis to be aligned according to the criteria defined by blumentritt 24 https://doi.org/10.33137/cpoj.v2i2.32955 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 3 cpoj pröbsting et al. 2019 gait characteristics of transtibial amputees data from a control group (cg), which had been included for comparison purposes, were obtained from the same database. these adult individuals were screened for orthopaedic and neurologic impairments and were not limited by conditions that could have affected their gait. the cg consisted of 52 individuals (25 male/27 female). they were on average 32 (sd=12) years old, 1.75 (sd=0.10) m tall and weighed 72.6 (sd=12.2) kg. all data analysed were collected at preferred self-selected and therefore comfortable and individually used walking speeds. the parameters of the groups were compared directly, even though the mean walking velocity differed between the amputees and the controls. the aim was to investigate the effect of normal, self-selected walking speed as an indication of the daily demands. data analysis three-dimensional marker trajectories were tracked from 17 markers placed on anatomical landmarks (both sides: acromion, epicondylus lateralis humeri, processus styloideus ulnare, trochanter major, compromise knee centre of rotation according to nietert,25 malleolus lateralis, caput os metartasale iv and three asymmetric markers: left tibia, right thigh and left shoulder blade). this marker set has been used since 1998 and was created to analyse essential gait parameters for amputees. external joint moments were calculated based on ground reaction forces and coordinates of joint axes according to a previously described method.26 for the typical characteristics of the tt gait, the ankle and knee angle in the sagittal plane of both prosthetic and sound limbs and also the sagittal moments of these joints were evaluated. due to the different results in literature, the vertical ground reaction force, and the sagittal and frontal moments acting on the sound knee joint were evaluated in this study. the first peak of vertical ground reaction forces, the peak knee flexion moment during midstance and the first peak knee adduction moment were used for the statistical analysis as a possible key factor for developing osteoarthritis. moreover, spatiotemporal gait parameters were reported as well: •gait velocity •step length •step length asymmetry (the difference between both legs) •stance phase duration •stance phase duration asymmetry (the difference between both legs) all kinetic and kinematic data were normalised to gait cycle (gc). the gc starts with the heel strike of one foot on the first force plate and ends with the following heel strike of the same side without touching the second force plate. the peaks of the kinetic data used for the statistical analysis are defined in table 1 and of the kinematic data are defined as follows: -first plantarflexion max.: range of motion from ankle angle at heel strike to maximum of plantarflexion (at 5-20% gc) -dorsiflexion max.: range of motion from maximum of plantarflexion (at 5-20% gc) to maximum of dorsiflexion (at 40-60% gc) -plantarflexion max.: range of motion from maximum of dorsiflexion (at 40-60% gc) to maximum of plantarflexion (at 50-70% gc) -knee joint stance flexion: range of motion from knee angle at heel strike to maximum of knee flexion (at 10-30% gc) -knee joint swing flexion: range of motion from maximum of knee extension (at 30-50% gc) to maximum of knee flexion (at 50-70% gc) since all prosthetic feet used in this study have no ankle joints, terms like "dorsiflexion" and "plantarflexion" have to be handled with care in kinematic as well as in kinetic analyses. they were used to explain the deflection of the foot related to the natural motion. statistical analysis mean values for all parameters were determined based on 8 to 12 gait cycles for the prosthetic and the sound limb. for the cg, the kinetic and kinematic data of the right leg and the spatiotemporal gait parameters were evaluated. group means were calculated separately for each group based on the values of all tts and the cg. differences in peak values of biomechanical parameters between amputees and the cg were tested with the mann-whitney u-test, based on a non-normal distribution of all gait parameters tested with the shapiro-wilk test. the significance level was set at p < 0.05 for two-tailed tests. the peaks of the knee adduction moment, of the knee flexion moment during midstance and of the vertical ground reaction forces on the sound side are reported contradictorily in literature. thus, their effect size (r=z/√n)) was calculated to assess the magnitude of the difference.27 as cohen suggested, the effect size was defined with d=0.2 being considered a 'small' effect size, 0.3 represents a 'medium' effect size and 0.5 a 'large' effect size.27 if the effect size of the group comparison is 0.2 or smaller, the difference is marginal. thus, the null hypothesis of the mann-whitney u-test stating that the two samples come from the same population and therefore show no differences is confirmed. results individuals the database contained data from 67 tts, whereby 53 (39 male, 14 female) met the inclusion criteria. the amputees were on average 48 (sd=16) years old, 1.77 (sd=0.09) m tall and weighed 84.3 (sd=17.8) kg. twenty five individuals were amputated on the right and 28 on the left side. all individuals used passive prosthetic feet. the amputees' mobility level (k-level) was determined by subjective judgment of the prosthetist using the medicare functional classification system (mfcl).28 detailed information on the amputees is shown in table 2. https://doi.org/10.33137/cpoj.v2i2.32955 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 4 cpoj pröbsting et al. 2019 gait characteristics of transtibial amputees table 1 t a b le 1 : le ft : c o m p a ri s o n o f th e r e s u lt s o f th e t t s ( tr a n s ti b ia l a m p u te e s ) w a lk in g w it h a c o n v e n ti o n a l o r e s r p ro s th e ti c f o o t, f o r th e s o u n d l e g ( s l ) a n d t h e p ro s th e s is l e g ( p l ) w it h t h e c o n tr o l g ro u p o f n o n -a m p u te e s ( n a ) in t h e i n d iv id u a l s tu d ie s . s ig n if ic a n t d if fe re n c e s i n t h e i n d iv id u a l s tu d y b e tw e e n t t s a n d c o n tr o ls a re m a rk e d i n b o ld a n d g re y . in t h e s tu d ie s o f b re a k e y 5 a n d l e m a ir e 3 , n o s ta ti s ti c a l d a ta w e re g iv e n . p le a s e n o te t h a t th e d a ta a re e x tr a c te d i n d if fe re n t w a y s . r ig h t: r e s u lt s o f th e p re s e n t s tu d y . m e a n p e a k v a lu e s o f s e le c te d k in e ti c a n d k in e m a ti c p a ra m e te rs i n c lu d in g i n fo rm a ti o n a b o u t s ta ti s ti c a l c o m p a ri s o n s b e tw e e n t t a n d c o n tr o l g ro u p o f n a a n d a b o u t s ta ti s ti c a l c o m p a ri s o n b e tw e e n p ro s th e ti c a n d s o u n d l im b . “= ”: d if fe re n c e b e tw e e n v a lu e s o f t t s a n d c g < = 2 d e g , 0 .0 5 n m /k g o r 2 % b w ; “ + ”: v a lu e i s i n c re a s e d f o r t t s ; ““: v a lu e i s r e d u c e d f o r t t s ; “* ”: p ≤ 0 .0 5 f o r c o m p a ri s o n b e tw e e n t t s a n d c g ; “* *” : p ≤ 0 .0 1 f o r c o m p a ri s o n b e tw e e n t t s a n d c g ; "∆ ": p ≤ 0 .0 5 f o r c o m p a ri s o n b e tw e e n s l a n d p l https://doi.org/10.33137/cpoj.v2i2.32955 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 5 cpoj pröbsting et al. 2019 gait characteristics of transtibial amputees table 2: transtibial amputees’ anthropometric data. patient height (cm) body mass with prosthesis (kg) age (yrs) follow up after amputation (yrs) reason for amputation gender (m/f) affected limb k-level (1-4) prosthetic foot model 1 188 99 63 8 malignancy m right 2-3 c-walk1 2 167 69 85 50 trauma m left 2 c-walk1 3 181 113 48 23 trauma m right 3 advantage dp1 4 182 72 22 8 trauma m left 3-4 c-walk1 5 173 76 76 59 trauma m left 3 dynamic motion1 6 181 81 34 n.a. trauma f left 3-4 c-walk1 7 175 92 63 44 trauma m left 3 dynamic motion1 8 190 92 63 n.a. arterial disease m left 2-3 c-walk1 9 185 87 62 n.a. n.a. m left 3 c-walk1 10 182 79 41 9 trauma m left 4 triton1 11 181 86 22 6 trauma m left 2 n.a. 12 172 87 66 2 arterial disease m left 1-2 dynamic foot1 13 160 61 46 21 trauma f left 2 multiflex2 14 180 85 52 29 trauma m left 4 triton1 15 193 115 43 15 trauma m left 4 trias1 16 175 94 62 1 arterial disease m right 3 dynamic motion1 17 176 75 63 39 trauma m right 3 c-walk1 18 171 69 22 3 trauma f right 3 c-walk1 19 179 71 68 1 arterial disease m right 2 dynamic foot1 20 179 80 47 0 trauma m left 3 c-walk1 21 187 88 71 8 trauma m left 3 c-walk1 22 172 60 27 3 trauma f left 2-3 c-walk1 23 170 70 34 6 arterial disease f left 3 dynamic motion1 24 156 63 44 1 arterial disease f right 2 sach1 25 179 95 64 3 arterial disease m left 2-3 dynamic foot1 26 176 67 28 3 trauma m left 3 dynamic foot1 27 159 64 46 24 trauma f left 3 c-walk1 28 186 79 29 29 congenital m left 4 c-walk1 29 174 92 62 3 arterial disease m right 2 dynamic foot1 30 173 91 59 4 arterial disease m right 1-2 greissinger plus1 31 176 73 43 26 trauma m left 3-4 dynamic motion1 32 175 80,5 73 54 trauma m right 3 dynamic motion1 33 181 84 52 20 trauma f right 3 c-walk1 34 180 92 65 4 arterial disease m left 3 c-walk1 35 169 76,5 70 71 trauma m left 3 sach1 36 203 144 25 8 trauma m right 2-3 ceterus3 37 173 77 50 31 trauma m right 4 triton1 38 176 93,5 53 1 sepsis m right 3-4 c-walk1 39 178 117 28 1 trauma m right 3 trias1 40 189 126 39 31 trauma m left 3 axtion1 41 168 76 37 24 malignancy f right 3 triton1 42 175 88 51 3 trauma m right 3 c-walk1 43 174 75 43 n.a. n.a. f left 2 n.a. 44 176 78 44 15 trauma f left 4 triton1 45 183 113 26 2 malignancy m right 4 triton1 46 165 69 47 2 arterial disease f right 3 ceterus lp3 47 172 72 41 20 trauma f left 4 c-walk1 48 156 53 40 33 trauma f right 3 axtion1 49 177 79 47 10 arterial disease m right 4 triton1 50 188 109 50 8 trauma m right 3-4 n.a. 51 168 70 28 20 trauma m right 4 advantage dp1 52 187 102 33 17 trauma m right 4 advantage dp1 53 183 69 48 2 infection m right 3 trias1 mean 176.9 84.3 48.0 16.7 39 m 25 right sd 9.1 17.8 15.7 17.3 14 f 28 left abbreviations: 1 ottobock, duderstadt d. 2 endolite blatchford, hampshire, uk. 3 össur, reykjavík, isl https://doi.org/10.33137/cpoj.v2i2.32955 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 6 cpoj pröbsting et al. 2019 gait characteristics of transtibial amputees spatiotemporal gait parameters tts walked significantly slower than the cg (1.26 m/s vs. 1.43 m/s; p<0.001). step length was significantly reduced: prosthetic side (0.71 m vs. cg: 0.76 m; p<0.05) and sound side (0.67 m vs. cg: 0.76 m; p<0.001). step length asymmetry was significantly higher for the amputees (0.046 m; p<0.001) than for the cg (0.01 m). stance phase duration on the sound side (65% of the gait cycle, gc) was significantly longer than on the prosthetic side (62% gc; p<0.001) and in the cg (61% gc; p<0.001). the asymmetry of the stance phase duration of 3% gc was significantly (p<0.001) increased. foot/ankle kinematics and kinetics prosthetic side the kinematic pattern (figure1a) of the prosthetic ankle differed from that found in the cg. the range of motion of plantarflexion in early stance on the prosthetic side (5.8°) was comparable to that of the cg (6.5°, p=0.2), while the movement was slower on the prosthetic side. the range of motion of the following dorsiflexion was also similar between both groups (15.4° vs. cg 16.5°; p=0.35). in the cg the movement was initially fast (up to 15% gc) and then it slowed down; between 10 and 50% gc, amputees’ dorsiflexion movement showed a constant velocity. the range of plantarflexion at the end of stance was significantly reduced on the prosthetic side (p: 13.9° and cg: 34.6°, table 1). additionally, there was negligible dorsiflexion during the swing phase of the prosthetic foot. figure 1: mean parameters for the prosthetic side foot/ankle of the tts with standard deviation (grey) and for the control group (dotted, black). a: mean pattern of foot/ankle motion, b: external sagittal moment acting on the ankle joint. the maximum initial plantarflexion moment (figure 1b) was significantly increased on the prosthetic side (-0.26 nm/kg and cg: -0.19 nm/kg; p=0.001). peak dorsiflexion moment was significantly reduced for the prosthetic side (p: 1.34 nm/kg and cg: 1.77 nm/kg; p<0.001). knee kinematics and kinetics prosthetic side for 46 out of 53 tts, the prosthetic side showed a knee flexion during stance phase. the remaining seven tts walked with fully extended knee. this motion ranged between 4 and 26 degrees with a mean stance phase flexion of 11.4° (figure 2a, table 1). this was significantly lower than in the cg (17.9°, p<0.001). the range of motion during swing on the patients’ prosthetic side (60.2°) was similar to that of the cg (59.6°). the moment acting on the knee joint in the sagittal plane was generally reduced on the prosthetic side (figure 2b). figure 2: mean parameters for the residual knee joint of the tts with standard deviation (grey) and for the control group (dotted, black). a: mean pattern of knee motion, b: external sagittal moment acting on the knee joint. sound side knee loading the peak values of the external knee extension moment showed no significant differences between tts and cg. however, the peak external knee flexion moment was significantly reduced on the sound side ( 0.47 nm/kg and cg: -0.64 nm/kg; p<0.001; r=0.3) (figure 3a and table 1). the first peak of the knee adduction moment showed no difference between the tts (0.51 nm/kg) and the cg (0.49 nm/kg; p=0.747; r=0.03). only the second peak was significantly reduced for the amputees (p=0.008) (figure 3b). the mean first peak of vertical ground reaction force showed no significant difference between the sound side of amputees (115.0 %bw) and the cg (115.4 %bw, p=0.686). only the mean second peak was significantly reduced for the amputees (p<0.001; r=0.04, figure 3c). https://doi.org/10.33137/cpoj.v2i2.32955 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 7 cpoj pröbsting et al. 2019 gait characteristics of transtibial amputees figure 3: selected mean parameters for the sound side of the tts with standard deviation (grey) and for the control group (dotted, black). a: external sagittal moment acting on the knee joint, b: external frontal moment acting on the knee joint, c: vertical ground reaction force. discussion the objective of this study was to describe the gait characteristics with respect to the sagittal kinetic and kinematic parameters of the ankle and knee joints of the prosthetic limb of unilateral tts. in view of the discrepancies of the sound side knee loading parameters found in the literature, these parameters were analysed in a representative large cross section of tts (n=53) as well. in the present study the tts walked with a self-selected speed comparable with velocities cited in other studies (see table 1), but significantly slower than the cg. the asymmetrical stance phase duration was also in accordance with the literature and was explained as “being the result of an early toe-off by the amputated limb owing to loss of the push-off function of ankle plantar-flexion”.5 the most obvious differences between tts and the cg were seen at the prosthetic ankle, as previously described by sanderson et al.7 with the tts, the external plantarflexion moment in early stance was clearly increased and acts for a longer period. also, plantarflexion was slower. this is in accordance with results of breakey, who argued that the compression of the prosthetic heel could be responsible for the longer period between heelcontact and foot-flat in the amputated limb5 as well as the missing ankle joint. the constant velocity of the subsequent dorsiflexion and the steady increase of the corresponding moment are results of the lack of muscular control, especially of the triceps surae. due to the removed plantar flexor muscles, the final plantarflexion at the end of stance was markedly reduced. as a result of this missing movement the peak dorsiflexion moment was subsequently reduced.7 the missing muscles controlling the ankle also affect the swing phase, because the prosthetic foot showed only a slight dorsiflexion, which could be due to elastic recoil after compression. in addition to the changes at the ankle, the residual knee of the prosthetic limb was systematically affected. during stance, the range of motion of the residual knee of the prosthetic limb was significantly reduced, although tts rarely suffer from pathological flexion or extension deficits of these joints. a long-term adaptation to the amputation is the reduction in strength29,30 and cross-sectional area9,31 of the muscles crossing the proximal joints. a possible consequence could be a reduction of the joint moments, which have to be compensated by the muscles.9 this reduction was also seen at the knee joint in this study as in other studies.4,16 the difference of the knee moments during midstance between the prosthetic side and the cg in this study was 0.46 nm/kg with a difference in gait velocity of 0.17 m/s. in general walking speed influences the magnitude of joint moment peaks. however, lelas et al.32 identified a parameter regression equation for this parameter. the result of this equation is that a reduction of velocity of 0.17 m/s will reduce the knee moment by 0.06 nm/kg.32 the difference of 0.46 nm/kg in this study with tts are more pronounced and therefore the reduction of the knee moment during midstance was attributed to the amputation. the absence of a forceful push-off in prosthetic feet during late stance caused by the lack of plantar flexor muscles could explain the reduction of moments in late stance. however, esposito et al. reported no differences for this parameter between a powered (biom) and a passive prosthetic foot.14 for the cohort analysed here, the mean stance phase knee flexion of 11.4° is was slightly more pronounced than reported in other studies with 7° to 9.5°.4,5,16 generally, knee flexion in early stance is significantly determined by the prosthetic alignment and the foot properties.26,33 the foot designs used here varied, but in all cases the foot was the “everyday foot” of the patients. the alignment used in this study was consistently biomechanically optimised24 for the patient group investigated. the comparably enhanced knee flexion during stance phase and the high percentage of amputees (87%) flexing the knee were achieved by an alignment which consistently followed blumentritt’s recommendations.24 this is an indicator for the importance of biomechanically optimised alignment and individually customised foot properties. https://doi.org/10.33137/cpoj.v2i2.32955 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 8 cpoj pröbsting et al. 2019 gait characteristics of transtibial amputees the kinematic changes compared to controls were only obvious during stance, when the prosthetic alignment and foot design are of importance. during swing the residual knee of the prosthetic limb showed no effects. this is in agreement with sanderson et al.7 and powers et al.4 but in contrast to the reduced peak knee flexion shown by breakey5 and rabago et al.16 the most inconsistent results in the literature were found with respect to kinetic compensatory adaptations on the sound side,17 especially the parameters that were assumed to be indicators for the risk of developing osteoarthritis. the present study shows no difference of the external knee adduction moment on the sound side compared to non-amputees. this concurs with lloyd et al.12, rabago et al.16 and karimi et al.17 in contrast, grabowski et al.13 and royer et al.18 showed an increase by trend, whereas esposito et al.14 and pruziner et al.15 showed a decrease by trend. none of the results shown by these studies are statistically significant. the sample of 53 subjects allows to claim equivalence within an effect size of r=0.03. therefore, it can be generally assumed that the knee adduction moment on the sound side does not differ between tts and non-amputees. the findings regarding peak external knee flexion moments on the sound side were also controversial. esposito (n=10)14 and nolan (n=4)8 reported a significant increase, whereas rabago et al. (n=16) showed a decrease by trend.16 this trend was supported with the results of this study showing a significant reduction in comparison to the controls with a medium effect. from these data with a large sample size it can be concluded that there is definitively no increase of knee flexion moment of tts compared with non-amputees. the vertical component of the ground reaction forces were also not consistently reported. some studies reported that the first ground reaction force peak was significantly greater on the sound side compared to healthy controls.10,13 other studies reported a statistically nonsignificant increase.14,15,17 the results of this study concur with sanderson et al.7 showing no difference between the sound side of the amputees and the cg. the effect size of r=0.04 also supports the null hypothesis that the two samples come from the same population and therefore show no differences. an essential factor influencing the sound side lower limb joint loading of tt amputees is the prosthetic alignment.24 in this context, grumillier demonstrated the influence of systematic prosthetic mal-alignment. particularly, the sound side’s hip work was increased, when the prosthetic foot was internally rotated.23 pinzur showed higher forces and moments on the sound side, when tilting the socket from an optimally aligned prosthesis.34 with a biomechanically optimised alignment as defined by blumentritt24 in the present study and in the results of karimi et al.17 no significant increase of knee moments and ground reaction forces could be measured on the sound side. furthermore, karimi et al. showed no significant increase of joint contact forces calculated by a musculoskeletal model in the intact knee joint of tts. hence, they could neither find any “biomechanical indicator for a possible early onset of osteoarthritis”.17 therefore, it seems reasonable to assume that an appropriately aligned prosthesis does not cause overloading of the sound side during walking. this concurs with hurley et al., who analysed the load of the contralateral limb in tt gait.35 it is questionable whether other parameters could explain the higher risk of knee osteoarthritis on the sound side knee of tts. proebsting et al. discussed the influence of sound side knee load during other activities e.g. hopping or walking with crutches without prosthesis.21 although an influence of trauma, infection or rheumatism on knee osteoarthritis is generally known. limitations it should be noted that the amputees in the analysed group used different models of prosthetic feet. furthermore, the amputees’ k-levels varied (table 2). however, since the aim of the study was to evaluate the general gait of a group of tts, we did not want to limit ourselves to investigating the specific gait with only one foot model or in one selected k-level and therefore decided to use a heterogeneous patient group. conclusion the biomechanical data measured for the prosthetic side in a cohort of 53 unilateral tt amputees concur with findings of other studies. these results indicate that besides the missing plantarflexion of the foot at late stance, the residual knee joint is generally affected with respect to a decreased sagittal plane moment and reduced knee flexion during stance phase. the parameters influencing the risk of developing knee osteoarthritis are discussed controversially in the literature for the sound side, but are by contrast not increased in the cohort of 53 unilateral tt amputees investigated here. hence, we deem it reasonable to assume that an appropriate prosthesis will reduce the likelihood of overloading the knee on the sound side during normal walking. nevertheless, other influencing factors next to biomechanical parameters during level walking (e.g. trauma, infection, rheumatism, etc.) could explain the higher risk of developing knee osteoarthritis in the sound side knee of tts. acknowledgements the authors gratefully acknowledge prof. d. rosenbaum for his valuable contributions to the preparation of this article. declaration of conflicting interests eva pröbsting, malte bellmann, thomas schmalz and andreas hahn are employees of ottobock, the manufacturer of prosthetic components. the authors alone are responsible for the content and writing of the paper. https://doi.org/10.33137/cpoj.v2i2.32955 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 9 cpoj pröbsting et al. 2019 gait characteristics of transtibial amputees ethical approval the study is in full accordance with the requirements of the german medical device act and data protection legislation. author contribution • dipl.-ing (fh) eva pröbsting, investigated, analysed the data and wrote the manuscript • dr. malte bellmann, investigated, analysed the data and reviewed • dr. andreas hahn, conceived the idea of the work and reviewed • dr. thomas schmalz, investigated, analysed the data and reviewed references 1.highsmith mj, kahle jt, miro rm, orendurff ms, lewandowski al, orriola jj, et al. prosthetic interventions for people with transtibial amputation: systematic review and meta-analysis of high-quality prospective literature and systematic reviews. j rehabil res dev. 2016; 1;53(2), 157-184. http://dx.doi.org/10.1682/jrrd.2015.03.0046 2.rusaw d, ramstrand n. motion-analysis studies of transtibial prosthesis users: a systematic review. prosthet orthot int. 2011; 35(1): 8-19. doi:10.1177/0309364610393060 3.lemaire ed, fisher fr. osteoarthritis and elderly amputee gait. arch phys med rehabil. 1994 oct; 75(10):1094-9.https://doi.org/10.1016/00039993(94)90084-1 4.powers cm, rao s, perry j. knee kinetics in trans-tibial amputee gait. gait posture. 1998; 8: 1-7. https://doi.org/10.1016/s0966-6362(98)00016-2 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prostheses. clin biomech. 2014; 29(10): 1186-1192. https://doi.org/10.1016/j.clinbiomech.2014.09.005 15. pruziner al, werner km, copple tj, hendershot bd, wolf ej. does intact limb loading differ in servicemembers with traumatic lower limb loss? clin orthop relat res. 2014; 472(10):3068-75. https://doi.org/10.1007/s11999-014-3663-1 16.rabago ca, wilken jm. the prevalence of gait deviations in individuals with transtibial amputation. mil med. 2016; 181 (11/12): 30-37. https://doi.org/10.7205/milmed-d-15-00505 17. karimi mt, salami f, esrafilian a, heitzmann dw, alimusaj m, putz c, et al. sound side joint contact forces in below knee amputee gait with an esar prosthetic foot. gait posture. 2017; 58(10):246-251. https://doi.org/10.1016/j.gaitpost.2017.08.007 18.royer td, koenig m. joint loading and bone mineral density in persons with unilateral, trans-tibial amputation. clin biomech. 2005; 20(10): 1119–1125. https://doi.org/10.1016/j.clinbiomech.2005.07.003 19. hurwitz de, ryals ab, case jp, block ja, andriacchi tp. the knee adduction moment during gait in subjects with knee osteoarthritis is more closely correlated with static alignment than radiographic disease severity, toe out angle and pain. j orthop res. 2002; 20(1): 101-7. https://doi.org/10.1016/s0736-0266(01)00081-x 20.mündermann a, dyrby co, andriacchi tp. secondary gait changes in patients with medial compartment knee osteoarthritis: increased load at the ankle, knee, and hip during walking. arthritis rheum. 2005; 52(9): 2835-44. https://doi.org/10.1002/art.21262 21.pröbsting e, blumentritt s, kannenberg a. changes in the locomotor system as a consequence of amputation of a lower limb [veränderungen am bewegungsapparat als folge von amputationen an der unteren extremität]. z orthop unfall. 2017; 155(1): 77-91. doi: 10.1055/s-0042112821 https://doi.org/10.33137/cpoj.v2i2.32955 pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees comparison of kinetics and kinematics with non-amputees. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.1. https://doi.org/10.33137/cpoj.v2i2.32955 10 cpoj pröbsting et al. 2019 gait characteristics of transtibial amputees 22.manal k, gardinier e, buchanan ts, snyder-mackler l. a more informed evaluation of medial compartment loading: the combined use of the knee adduction and flexor moments. osteoarthr. cartil. 2015: 23(7): 11071111. https://doi.org/10.1016/j.joca.2015.02.779 23. grumillier c, martinet n, paysant j, andré jm, beyaert c. compensatory mechanism involving the hip joint of the intact limb during gait in unilateral trans-tibial amputees. j biomech. 2008; 41(14): 2926-31. https://doi.org/10.1016/j.jbiomech.2008.07.018 24.blumentritt s, schmalz t, jarasch r, schneider m. effects of sagittal plane prosthetic alignment on standing trans-tibial amputee knee loads. prosthet orthot int. 1999; 23(3): 231-8. doi: 10.3109/03093649909071639 25.nietert m. the compromise pivot axis of the knee joint: studies of the kinematics of the human knee joint in regard to their approximation in prosthetics. shaker; isbn-10: 3832273883; 2008. 26.schmalz t, blumentritt s, jarasch r. energy expenditure and biomechanical characteristics of lower limb amputee gait: the influence of prosthetic alignment and different prosthetic components. gait posture. 2002; 16: 255–263. https://doi.org/10.1016/s09666362(02)00008-5 27.fritz co, morris pe, richler jj. effect size estimates: current use, calculations, and interpretation. j. exp. psychol. gen. 2011;141(1):2-18. https://doi.org/10.1037/a0024338 28.centers for medicare and medicaid services. medicare region c durable medical equipment prosthetics orthotic supplier (dmepos) manual. columbia, sc: palmetto gba, 2005, pp. 53.5–53.6. 29.isakov e, burger h, gregoric m, marincek c. stump length as related to atrophy and strength of the thigh muscles in trans-tibial amputees. prosthet orthot int. 1996; 20(2): 96–100. doi: 10.3109/03093649609164425 30. tugcu i, safaz i, yilmaz b, göktepe as, taskaynatan ma, yazicioglu k. muscle strength and bone mineral density in mine victims with transtibial amputation. prosthet orthot int. 2009; 33(4): 299–306. https://doi.org/10.3109/03093640903214075 31.renstrom p, grimby g, morelli b, palmertz b. thigh muscle atrophy in below-knee amputees. scand j rehabil med. 1983; 9(): 150–162. 32.lelas jl, merriman gj, riley po, kerrigan dc. predicting peak kinematic and kinetic parameters from gait speed. gait posture. 2003; 17(2):106-12. https://doi.org/10.1016/s0966-6362(02)00060-7 33.andres ro, stimmel sk. prosthetic alignment effects on gait symmetry: a case study. clin biomech. 1990; 5(4): 88-96. https://doi.org/10.1016/0268-0033(90)90043-6 34. pinzur ms, cox w, kaiser j, morris t, patwardhan a, vrbos l. the effect of prosthetic alignment on relative limb loading in persons with trans-tibial amputation: a preliminary report. j rehabil res dev. 1995; 32(4): 373-7. 35. hurley gr, mckenney r, robinson m, zadravec m, pierrynowski mr. the role of the contralateral limb in below-knee amputee gait. prosthet orthot int. 1990; 14: 33-42. https://doi.org/10.3109/03093649009080314 https://doi.org/10.33137/cpoj.v2i2.32955 shoemaker e. myoelectric elbow-wrist-hand orthosis with active grasp for patients with stroke: a case series. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32022 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) myoelectric elbow-wrist-hand orthosis with active grasp for patients with stroke: a case series eric shoemaker, ability prosthetics and orthotics, inc. 2005 technology parkway, mechanicsburg, pennsylvania, usa. email: eric.shoemaker@abilitypo.com doi: https://doi.org/10.33137/cpoj.v1i2.32022 introduction this case series presents prescription, evaluation, fitting and initial functional benefits of a myoelectric elbow wrist-hand orthosis with active grasp. custom fit, myoelectric orthoses are now also being provided to patients with upper extremity paresis due conditions such as stroke, brachial plexus injury, spinal cord injury, multiple sclerosis and amyotrophic lateral sclerosis to enable them to self-initiate and control movement of a partially paretic limb using their own volitional myoelectric signals. a recent study of 18 chronic stroke participants demonstrated functional improvements on the fugl-meyer impairment scale (fm) and a battery of functional tasks with this device.1 methods patients are currently being evaluated by an interdisciplinary team at the lebanon, pa outpatient va clinic for the myopro 2 motion g device (myomo inc., cambridge, ma). two recent candidates who received the device were followed to evaluate the functional benefits they experienced. patient 1: 67 year old male s/p cva in 2013 affecting his right side. patient 2: 61 year old male s/p cva in 2014 affecting his right side. both men were previously right hand dominant, both present with high motivation, and both have a strong family and care-giver support structure in place. during initial consultation, passive and active rom were assessed as well as mmt. emg signals were tested with the wrist flexors and extensors as well as biceps and triceps. both men were able to generate and sustain an emg signal for all 4 sites. both men completed initial surveys with the disabilities of the arm shoulder and hand (dash). patient 1 scored 85 and patient 2 scored 67.5. a battery of functional tasks was also used to evaluate current deficits. the tasks included: lifting a laundry basket, bringing a spoon to the mouth, drink from a cup, turning on a light switch. both patients were casted by a certified orthotist using fiberglass wrap from the level of the axilla and to include the hand in a neutral position. the cast was taken in one segments with assistance to capture the desired position at each joint. the custom myopro 2 motion g was fabricated by a central fabricator, and the device was fit within 3 weeks of casting. no adjustments were needed at the time of fitting. programming was performed by the certified orthotist to optimize control of the device. both patients began using biceps mode for elbow control and voluntary opening for grasp control. the software made it possible to change the control strategy of the device for better control of the assistive device for adls, because initially both patients struggled to control the elbow and grasp with independent and separate emg signals from antagonist muscle groups. both patients were referred to occupational therapy by a clinician trained in using the myopro. results upon fitting of the myopro motion g, both patients were able to control flexion and extension of the elbow and open and close of the fingers. the patients still struggled to drink from a cup and bring a spoon to their mouths with the device but patient 2 was able to pick up a laundry basket and turn on a light switch with the device and was unable without. active rom was measured and showed an increase in both patients when wearing their myopro motion g devices. patient 1 experienced an improvement in active rom in elbow flexion of 10 degrees and elbow extension of 50 degrees with the myopro. patient 2 showed a 35 deg improvement in elbow with the myopro. active rom with and without the myopro is depicted in table 1. conclusion this case series highlights the unique orthotic intervention to restore active motion and independence with the upper extremity now available to patients with stroke. initial fitting of the myopro 2 motion g mailto:eric.shoemaker@abilitypo.com https://doi.org/10.33137/cpoj.v1i2.32022 shoemaker e. myoelectric elbow-wrist-hand orthosis with active grasp for patients with stroke: a case series. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, oral presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32022 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (oral presentation) demonstrated increased active rom of the both the elbow and the fingers for 3 jaw chuck grasp. both patients showed an increase in active rom with the myopro. these patients are expected to continue to follow up, and their progress with the myopro 2 motion g will be documented throughout their recovery. significance patients who’ve suffered a cva have the potential to increase independence when performing certain activities of daily living. the ability to position the hand in space via elbow control and then grasp an object with the myopro can allow patients to perform bimanual activities such as lifting and carrying and laundry basket as was demonstrated here. references 1. peters, ht. "giving them a hand: wearing a myoelectric elbow-wrist-hand orthosis reduces upper extremity impairment in chronic stroke." arch. of pm&. pp 1821827, 2017. doi:10.1016/j.apmr.2016.12.016 2. takahashi kz & stanhope sj. asb annual meeting, boston, ma, usa, 2015. disclosure the authors are employed by ability prosthetics and orthotics, inc. and have no conflict of interest to report related to this case series. https://doi.org/10.1016/j.apmr.2016.12.016 gholizadeh h, lemaire ed, salekrostam r. mechanical evaluation of unity elevated vacuum suspension system. canadian prosthetics & orthotics journal. 2019; volume2, issue2, no.5. https://doi.org/10.33137/cpoj.v2i2.32941 issn: 2561-987x volume 2, issue 2 2019 (online) r e s e a r c h a r t i c l e all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). https://doi.org/10.33137/cpoj.v2i2.32941 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation 1 open access mechanical evaluation of össur unity suspension system volume 2, issue 2, article no.5, 2019 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index research article mechanical evaluation of unity elevated vacuum suspension system gholizadeh h1*, lemaire ed1,2, salekrostam r3 1 ottawa hospital research institute, centre for rehabilitation research and development, ottawa, canada. 2 faculty of medicine, university of ottawa, ottawa, canada. 3 faculty of engineering, department of mechanical engineering, university of ottawa, ottawa, canada. introduction the method for attaching a prosthesis to the body is termed prosthetic suspension. selecting a suitable suspension system is an important step in the prosthetic rehabilitation process.1–4 a better understanding of prosthetic suspension systems may facilitate selection based on the amputee’s needs, leading to better socket system performance.2,5,6 small residual limb-socket displacement is a good indicator of prosthetic suspension system quality.7,8 various prosthetic suspension approaches are used in clinical practice. a thigh corset was traditionally used for suspension, but introduction of the patellar-tendon bearing prosthesis lead to other suspension methods; such as, cuff, supracondylar-suprapatellar, and suprapatellar strap.2,6 the icelandic roll-on silicone socket (iceross) system was introduced to the rehabilitation market to improve suspension via close adhesion of the silicone liner to the residual limb skin.2,6 various methods are used to hold the silicone liner inside the prosthetic socket; including, single distal pin/lock, lanyard, suction, seal-in, or vacuum. a standard lock system for all amputees has not been defined.1,2,6 vacuum assisted suspension systems (vass) add an externally generated vacuum to a liner-based suspension abstract background: small residual limb-socket displacement is a good indicator of prosthetic suspension system quality. active vacuum suspension systems can decrease vertical movement inside the socket, compared to non-active suction systems. this study mechanically evaluated limb-socket displacement with the össur unity active vacuum system. method: forty-eight conditions were evaluated: four cylindrical and four conical sockets (polypropylene, polyethylene terephthalate glycol-modified (petg), thermoset resin (acrylic), thermolyn soft materials); two iceross seal-in v liners (standard, high profile); three vacuum conditions (active vacuum, inactive vacuum, no suction with valve open). an instron 4428 test machine applied 0-100n linear ramped tensile loads to each positive mold, with the socket secured in place, while displacement between the mold and socket was recorded. following the displacement tests, the load before failure (i.e., 10 mm displacement) was measured. results: average and standard deviations for movement between the mold and sockets were small. the displacement average for all conditions was 0.30±0.16mm for active vacuum, 0.32±0.16mm for inactive vacuum, and 0.39±0.22mm for no suction. across all trials, active vacuum systems tolerated significantly (p<0.001) more load before failure (812±221n) compared to inactive vacuum (727±213n), and no suction (401±184n). the maximum load before failure (1142±53n) was for the cylindrical polypropylene socket and high-profile liner. conclusion: the unity system successfully controlled pistoning inside the socket for regular activity loads and also controlled the greatest traction loads. while relative movement was smallest for unity, all conditions (inactive vacuum, no suction) were viable for loads less than 100n. furthermore, similar results can be achieved when using different socket fabrication materials. citation gholizadeh h, lemaire ed, salekrostam r. mechanical evaluation of unity elevated vacuum suspension system. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.5. https://doi.org/10.33137/cpoj.v2i2.32 941 keywords prosthesis, amputation, prosthetic limb, elevated vacuum, prosthetic suspension system, rehabilitation *corresponding author hossein gholizadeh, bsc (p&o), meng.sc, phd, ottawa hospital research institute, centre for rehabilitation research and development, ottawa, canada. email: gholizadeh87@yahoo.com orcid: https://orcid.org/0000-0001-5847-7985 doi: https://doi.org/10.33137/cpoj.v2i2.32941 article info received: july 20, 2019 accepted: march 16, 2020 published: march 20, 2020 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v2i2.32941 https://doi.org/10.33137/cpoj.v2i2.32941 mailto:gholizadeh87@yahoo.com https://doi.org/10.33137/cpoj.v2i2.32941 gholizadeh h, lemaire ed, salekrostam r. mechanical evaluation of unity elevated vacuum suspension system. .canadian prosthetics & orthotics journal. 2019; volume2, issue2, no.5. https://doi.org/10.33137/cpoj.v2i2.32941 2 cpoj gholizadeh et al. 2019 mechanical evaluation of össur unity suspension system system to decrease pistoning within the socket, reduce residual limb volume loss over time, and improve prosthesis control and proprioception.1,3,9,10 street11 mentioned that vacuum could eliminate movement and reduce shear, provide a healthier environment for the residual limb, and prevent volume loss. rosenblatt12 also reported that elevated vacuum systems can improve maximum walking speed, comfort, and gait symmetry compared to suction sockets and sleeve suspension systems.12 while elevated vacuum systems may have some benefits over the other suspension systems and improve amputee quality of life, these systems may not be appropriate for all amputees since donning the prosthesis requires more procedures, and amputees must deal with the liners, sleeves, controls, etc.13–16 moreover, air between the liner and skin may create skin blisters.16 recently, the unity elevated vacuum suspension system (https://assets.ossur.com/library/31882/ifu) was developed by össur. unity consists of a mechanical vacuum pump in the foot shell, which uses prosthetic foot motion to draws air out from the socket in each step. unity includes a hypobaric sealing membrane around a silicon liner so that an external sleeve is not required, unlike other vacuum systems on the market such as harmony (ottobock) or limblogicvs (ohio willow wood). external sleeves can restrict knee range of motion, retain heat and therefore create perspiration problems, and may be replaced regularly due to sleeve punctures.2 seal-in v liners are used and are available as standard and high profile options with only cylindrical shape. the high profile liner has a more proximal sealing membrane and is used when the person has sensitive locations on the distal tibial crest or a long residual limb. the high profile liner may have better pistoning control than standard profile due to larger vacuum area. the manufacturer suggests a thin layer of polyethylene terephthalate glycol-modified (petg) materials over the positive cast before socket fabrication with thermoset resin (acrylic). however, petg material is rigid and not suitable for people who want flexible inner socket. therefore, investigating other materials for socket fabrication could be of benefit to amputees. pistoning measurement has been used to evaluate suspension system quality for static and dynamic conditions.7,8,13,14,18–22 testing involves applying a tensile load to the socket and then measuring displacement between the socket and limb. test loads are based on swing phase forces during gait, with typical prosthetic limb tensile loads of 44.5n during walking and 88.9n during running.1,7 this load is applied to the suspension system in less than one second and depends on prosthetic weight and walking speed. currently, research is lacking on how the unity elevated vacuum system controls pistoning within the socket, with different socket materials. this information is important to guide prosthetic prescription and to characterize this technology within the current scope of prosthetic suspension systems. therefore, mechanical testing was conducted to provide quantitative evidence to guide clinical practice. methodology the össur unity elevated vacuum suspension system was used in this project. to provide a repeatable and standardized socket and limb surrogate, two reusable positive model (cylindrical and conical shapes) were made from plaster and covered with plastazote medium foam (2cm) and leather to simulate skin and soft tissue (figure 1). the model dimensions were obtained from campbell, et al.23 each positive model retained a steel mandrel in the proximal end. the reusable positive molds were only used during mechanical testing and not for socket fabrication. to avoid plastazote compression under vacuum while laminating/thermoforming the sockets (figure 2), molds were casted with plaster of paris (figure 2,e) and then reusable positive plaster models were fabricated (figure 2,f). the positive models were used for socket fabrication. figure 1: positive mold. left: cross-sectional view of positive mold (conical shape); right: socket dimensions. the cylindrical and conical mold were used to fabricate eight sockets, based on the unity manufacturer guidelines, with standard and high profile iceross seal-in v liners and four materials: polypropylene (pp), polyethylene terephthalate glycol-modified (petg), thermoset resin (acrylic), thermolyn soft (figure 2). a custom adaptor was attached to the socket’s distal end. a valve from the unity transtibial kit was attached to the socket wall below the liner seal position. socket displacement was measured for active vacuum (-18inhg), inactive vacuum (i.e., acting as a suction suspension system), and no suction (i.e., valve in open position) conditions. as shown in figure 2(h), the prosthetic foot vacuum pump was attached to the socket and a pressure gauge (mini dial air pressure gauge meter) was used to check negative pressure inside the socket. the gauge was in series with the unity tube and pump. we created -18inhg for active vacuum by simulating prosthetic foot motion to draw air out from the socket. an instron 4482 tensile test machine was used to apply ramped tensile loads and measure displacement. the positive mold’s mandrel was attached to the instron’s superior grip and the socket’s distal adapter was connected to the instron’s inferior grip (i.e., fixed, non-moving attachment). the positive molds were pulled with linear ramped loads from 0 to 100 n, over 1 second. a 100n maximum load encompasses the typical range of lower limb loads in daily living.7,21 following the displacement tests, the load that each condition can tolerate before the suspension failed was measured. a 10-mm displacement between mold and socket was considered as failure since amputees consider https://doi.org/10.33137/cpoj.v2i2.32941 https://assets.ossur.com/library/31882/ifu gholizadeh h, lemaire ed, salekrostam r. mechanical evaluation of unity elevated vacuum suspension system. .canadian prosthetics & orthotics journal. 2019; volume2, issue2, no.5. https://doi.org/10.33137/cpoj.v2i2.32941 3 cpoj gholizadeh et al. 2019 mechanical evaluation of össur unity suspension system sockets to fit well and to be secure with displacements of less than 10 mm.8 a total of 48 test conditions were evaluated (figure 3). these conditions included: socket shape (cylindrical, conical), socket material (polypropylene, polyethylene terephthalate glycol-modified, thermoset resin, thermolyn soft material), liner seal position (high profile, standard profile), and vacuum (active vacuum, inactive vacuum, no suction). ten trials were completed for each test condition. a review paper by eshraghi et al.,7 showed that different techniques have been used to measure pistoning inside the socket and only five studies21,24–27 completed 3 to 5 trials due to ethical considerations related to the x-ray exposure. this study included 10 trials which provide more reliable analysis than other reviewed studies. the liners and mold were examined after each test to ensure that no damage or changes occurred. moreover, a minimum of 5 minutes between tests allowed the plastazote to return to its original shape. figure 2: sockets fabrication and mechanical testing. a-g: process of making cylindrical and conical sockets; h: mechanical testing. data analysis positive mold displacements were extracted using the instron bluehill 2 software and imported into excel for analysis. maximum displacement was determined for each 100n load trial and averages and standard deviations (sd) were calculated across the 10 trials for each test condition. for the suspension failure tests, the failure load was determined for each trial and averages and sd were calculated across the 10 trials for each test condition. statistical analyses were performed using spss 23 and the normality of variables was verified by the shapiro-wilk normality test. a one-way repeated measures analysis of variance (anova) with post hoc bonferroni analysis was used to compare active vacuum, inactive vacuum, and no suction conditions. moreover, a paired samples t-test was used to compare seal-in v high profile and standard profile liners. the significance level was set at 0.05. figure 3: tensile tests (48 combinations). pp (polypropylene); petg (polyethylene terephthalate glycol-modified); resin (thermoset resin); ts (thermolyn soft). results average and standard deviations for movement between the positive molds and sockets were small (table 1). across all conditions, the average displacement was 0.30±0.16mm for active vacuum, 0.32±0.16mm for inactive vacuum, and 0.39±0.22mm for no suction. overall, less movement was measured with conical socket shapes (0.28±0.16mm) compared to cylindrical sockets (0.33±0.17mm) in active vacuum condition when 100n traction load applied. https://doi.org/10.33137/cpoj.v2i2.32941 gholizadeh h, lemaire ed, salekrostam r. mechanical evaluation of unity elevated vacuum suspension system. .canadian prosthetics & orthotics journal. 2019; volume2, issue2, no.5. https://doi.org/10.33137/cpoj.v2i2.32941 4 cpoj gholizadeh et al. 2019 mechanical evaluation of össur unity suspension system overall, active vacuum systems tolerated significantly (p<0.001) more load before failure (812±221n), compared to inactive vacuum (727±213n) and no suction (401±184n). with active vacuum, the maximum load before failure (1142±53n) was for the cylindrical polypropylene socket and high-profile liner. the minimum load was recorded with the petg conical socket and standard profile liner in active vacuum (442±42n) and open valve conditions (151± 15n). for the passive condition, the minimum load was recorded with the polypropylene conical socket and standard profile liner (324.8±5n). with active vacuum, an average of 958±179n was required to displace positive molds with high profile liners, compared to 665±155n for standard liners (p<0.001). moreover, the two socket shapes were significantly different (p<0.01) since more load was needed for 10 mm displacement in cylindrical sockets (905±183n), compared to conical sockets (718±227n) when using active vacuum (table 1, figure 4-figure 7). discussion mechanical testing was conducted to evaluate the össur unity elevated vacuum suspension system’s ability to minimize socket displacement when external traction forces are applied. the results of this study showed that the unity system successfully controlled socket pistoning and different materials can be used for socket fabrication. from the literature, vacuum and suction suspension systems could diminish residual limb displacement inside the socket.13,28 klute et al. measured pistoning with a motion analysis system while their participants stood in place and shifted their weight from side to side (i.e., weighted and un-weighted).13 socket liner vacuum displacement at 100n load p-value* load at 10mm displacement p-value* resin conical standard profile on 0.45±0.04 (1,2) 1.000 562.4±14.10 (1,2) 0.001 off 0.45±0.04 (1,3) 1.000 521.3±5.22 (1,3) 0.001 valve open 0.47±0.05 (2,3) 1.000 214.2±12.78 (2,3) 0.001 high profile on 0.22±0.03 (1,2) 1.000 701.5±10.85 (1,2) 0.001 off 0.22±0.01 (1,3) 0.001 562.6±15.96 (1,3) 0.001 valve open 0.30±0.02 (2,3) 0.001 258.0±5.60 (2,3) 0.001 resin cylindrical standard profile on 0.37±0.01 (1,2) 0.237 711.9±4.80 (1,2) 0.001 off 0.38±0.02 (1,3) 0.001 671.1±3.57 (1,3) 0.001 valve open 0.61±0.03 (2,3) 0.001 252.1±2.35 (2,3) 0.001 high profile on 0.24±0.04 (1,2) 0.146 905.7±28.02 (1,2) 0.001 off 0.27±0.01 (1,3) 0.206 706.7±31.72 (1,3) 0.001 valve open 0.27±0.01 (2,3) 1.000 476.7±8.81 (2,3) 0.001 petg conical standard profile on 0.60±0.11 (1,2) 1.000 442.2±42.37 (1,2) 0.026 off 0.60±0.07 (1,3) 0.022 398.5±45.00 (1,3) 0.001 valve open 0.76±0.10 (2,3) 0.010 151.34±14.70 (2,3) 0.001 high profile on 0.19±0.01 (1,2) 0.222 786.5±55.11 (1,2) 0.986 off 0.20±0.02 (1,3) 0.001 764.5±32.66 (1,3) 0.001 valve open 0.21±0.01 (2,3) 0.019 453.7±14.37 (2,3) 0.001 petg cylindrical standard profile on 0.71±0.23 (1,2) 1.000 741.9±19.32 (1,2) 0.037 off 0.74±0.08 (1,3) 0.314 711.4±22.48 (1,3) 0.001 valve open 0.92±0.10 (2,3) 0.002 323.5±10.53 (2,3) 0.001 high profile on 0.20±0.02 (1,2) 0.153 1060.5±20.48 (1,2) 0.076 off 0.22±0.06 (1,3) 0.001 915.8±140.81 (1,3) 0.001 valve open 0.24±0.01 (2,3) 0.813 663.7±116.49 (2,3) 0.013 polypropylene conical standard profile on 0.23±0.10 (1,2) 0.413 446.6±14.98 (1,2) 0.001 off 0.29±0.02 (1,3) 0.439 324.8±5.02 (1,3) 0.001 valve open 0.30±0.06 (2,3) 1.000 280.3±31.16 (2,3) 0.001 high profile on 0.14±0.02 (1,2) 0.020 805.3±18.35 (1,2) 0.001 off 0.19±0.01 (1,3) 0.001 701.4±31.07 (1,3) 0.001 valve open 0.23±0.01 (2,3) 0.001 323.1±17.75 (2,3) 0.001 polypropylene cylindrical standard profile on 0.38±0.10 (1,2) 0.657 751.9±54.63 (1,2) 0.001 off 0.38±0.03 (1,3) 0.001 688.5±11.19 (1,3) 0.001 valve open 0.54±0.02 (2,3) 0.001 277.1±1.69 (2,3) 0.001 high profile on 0.17±0.03 (1,2) 0.141 1141.7±52.64 (1,2) 0.003 off 0.19±0.01 (1,3) 0.032 1061.7±40.78 (1,3) 0.001 valve open 0.20±0.01 (2,3) 0.158 709.0±99.65 (2,3) 0.001 thermolyn soft conical standard profile on 0.20±0.01 (1,2) 1.000 855.2±23.82 (1,2) 0.002 off 0.20±0.01 (1,3) 0.496 801.3±29.39 (1,3) 0.001 valve open 0.21±0.01 (2,3) 0.261 469.6±11.39 (2,3) 0.001 high profile on 0.18±0.01 (1,2) 0.211 1126.4±36.97 (1,2) 0.001 off 0.19±0.01 (1,3) 0.001 1073.2±11.26 (1,3) 0.001 valve open 0.20±0.01 (2,3) 0.004 748.4±28.84 (2,3) 0.001 thermolyn soft cylindrical standard profile on 0.33±0.02 (1,2) 0.732 793.0±40.24 (1,2) 0.001 off 0.34±0.02 (1,3) 0.001 752.2±14.14 (1,3) 0.001 valve open 0.47±0.03 (2,3) 0.001 285.9±10.38 (2,3) 0.001 high profile on 0.21±0.04 (1,2) 1.000 1136.1±58.83 (1,2) 0.001 off 0.21±0.01 (1,3) 0.060 971.0±13.56 (1,3) 0.001 valve open 0.23±0.01 (2,3) 0.009 528.6±10.92 (2,3) 0.001 table 1: average and standard deviations for displacement (mm) and load (n) before failure. * p values for valve setting comparisons: 1=on, 2=off, 3=valve open. https://doi.org/10.33137/cpoj.v2i2.32941 gholizadeh h, lemaire ed, salekrostam r. mechanical evaluation of unity elevated vacuum suspension system. .canadian prosthetics & orthotics journal. 2019; volume2, issue2, no.5. https://doi.org/10.33137/cpoj.v2i2.32941 5 cpoj gholizadeh et al. 2019 mechanical evaluation of össur unity suspension system figure 4: average displacement (mm) and load (n) in conical socket with seal-in v standard profile. figure 5: average displacement (mm) and load (n) in conical socket with seal-in v high profile. https://doi.org/10.33137/cpoj.v2i2.32941 gholizadeh h, lemaire ed, salekrostam r. mechanical evaluation of unity elevated vacuum suspension system. .canadian prosthetics & orthotics journal. 2019; volume2, issue2, no.5. https://doi.org/10.33137/cpoj.v2i2.32941 6 cpoj gholizadeh et al. 2019 mechanical evaluation of össur unity suspension system figure 6: average displacement (mm) and load (n) in cylindrical socket with seal-in v high profile. figure 7: average displacement (mm) and load (n) in cylindrical socket with seal-in v standard profile. https://doi.org/10.33137/cpoj.v2i2.32941 gholizadeh h, lemaire ed, salekrostam r. mechanical evaluation of unity elevated vacuum suspension system. .canadian prosthetics & orthotics journal. 2019; volume2, issue2, no.5. https://doi.org/10.33137/cpoj.v2i2.32941 7 cpoj gholizadeh et al. 2019 mechanical evaluation of össur unity suspension system residual limb pistoning was significantly less (1±3mm) with the harmony suspension system providing active vacuum than a pin/lock system (6±4mm).13 the results of this study showed that after applying 100n traction load, only 0.30±0.16 mm of displacement was found with active vacuum across all conditions. another study21 revealed that adding up to 90n loads to the prosthesis caused less pistoning in a suction socket using seal-in x5 liner (2±1mm) compared to a pin/lock system (5±2 mm). in the current study, 0.32±0.16mm pistoning inside the suction socket was recorded overall (average for all conditions). this result is lower than the previous studies on different suspension system13,21 and showed that the seal-in v could control the movement inside the socket successfully. gholizadeh et al., 2014, showed that a seal-in x5 liner with petg socket tolerated 310n loads before suspension failure, pin/lock systems tolerated 580 n, and magnetic suspension systems tolerated 351n.29 in this study, the maximum load that each condition could tolerate before suspension failure was up to 86% higher than other studies in the literature.29,30 while the manufacturer suggested petg materials for the unity socket fabrication, the results of this study showed that different materials can be used without sacrificing suspension performance. wirta et. al.,31 compared the vertical movement of conical and cylindrical residual limb shapes with patellar tendon bearing (ptb) sockets and different suspension systems (i.e., supracondylar/suprapatellar, supracondylar, cuff, waistband and cuff, figure-eight strap, rubber sleeve, articulated supracondylar wedge). in both conical and cylindrical residual limbs, the rubber sleeve produced the least pistoning of the seven evaluated systems (ranged from 6 to 31mm for all system), and the cylindrical residual limb had more pistoning compared to conical stump.31 similarly, less movement was seen in this study with conical socket shape compared to cylindrical socket when 100n traction load applied, but the average difference was small (0.05 mm). literature has shown that donning and doffing the prosthesis is challenging for elderly amputees using sealin x5 liner.2,22 this study showed that a minimum of 151±15n was needed with the petg conical socket and standard profile liner in open valve condition to pull off the socket, and a maximum of 748±291n was needed for the thermolyne soft socket. therefore, petg would be good choice for amputees who may have difficulty doffing their prosthesis. limitations in this study, plaster positive molds were used and covered with plastazote and leather,32 and were pulled straight using an instron test machine. in practice, the prosthesis user could wiggle their residual limb to remove their prosthesis with less force. future research is needed to evaluate donning/doffing procedures in transtibial amputees. reusable molds, covered with plastazote foam and leather, were used to represent a residual limb; however, silicone materials might be a better option to simulate the soft tissue than plastazote.33 conclusion the unity system successfully controlled pistoning inside the socket for regular activity loads and also controlled the greatest traction loads. while relative movement was smallest for the unity, the inactive vacuum (suction) condition was also viable for loads less than 100n. this study showed that the unity system can hold the residual limb inside the socket successfully even if there is a failure in the vacuum pump. acknowledgements the authors would like to thank knut lechler, and kristleifur kristjansson for providing technical advice and support. natalie baddour and francois robitaille are thanked for assistance with mechanical testing. declaration of conflicting interests the authors have declared that no competing interests exist. no commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated. author contribution • hossein gholizadeh, designed the system and the protocol, conducted the experiments, collected and analyzed the data, discussed the results and drafted the manuscript. • edward d lemaire, supervised the overall project, and helped in writing and revising the manuscript. • rasool salekrostam, conducted mechanical testing, collected and analyzed the data. sources of support this study was financially supported by össur and mitacs. references 1.board wj, street gm, caspers c. a comparison of trans‐tibial amputee suction and vacuum socket conditions. prosthet orthot int. 2001; 25(3): 202–9. 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residual femur within a trans–femoral socket during gait. prosthet orthot int. 2000; 24(3):226–32. https://doi.org/10.1080/03093640108726605 19. lilja m, johansson t, öberg t. movement of the tibial end in a ptb prosthesis socket: a sagittal x-ray study of the ptb prosthesis. prosthet orthot int. 1993; 17(1):21–6. https://doi.org/10.3109/03093649309164351 20. söderberg b, ryd l, persson bm. roentgen stereophotogrammetric analysis of motion between the bone and the socket in a transtibial amputation prosthesis: a case study. j prosthet orthot. 2003; 15(3):95–9. doi: 10.1097/00008526-200307000-00008 21. gholizadeh h, abu osman na, kamyab m, eshraghi a, wan abas ab, azam mn. transtibial prosthetic socket pistoning: static evaluation of seal-in® x5 and dermo® liner using motion analysis system. clin biomech. 2012; 27(1):34–9. https://doi.org/10.1016/j.clinbiomech.2011.07.004 22. gholizadeh h, abu osman na., eshraghi, a, ali, s, wan abas ab, et al. transtibial prosthetic suspension: less pistoning versus easy donning and doffing. j rehabil res dev. 2012; 49(9):1321. http://dx.doi.org/10.1682/jrrd.2011.11.0221 23. campbell ai, sexton s, schaschke cj, kinsman h, mclaughlin b, boyle m. prosthetic limb sockets from plantbased composite materials. prosthet orthot int. 2012; 36(2):181–9. https://doi.org/10.1177/0309364611434568 24. sanders je, karchin a, fergason jr, sorenson ea. a noncontact sensor for measurement of distal residual-limb position during walking. j rehabil res dev. 2006; 43(4):509. doi: 10.1682/jrrd.2004.11.0143 25. narita h, yokogushi k, shi s, kakizawa m, nosaka t. suspension effect and dynamic evaluation of the total surface bearing (tsb) trans-tibial prosthesis: a comparison with the patellar tendon bearing (ptb) trans-tibial prosthesis. prosthet orthot int. 1997; 21(3):175–8. https://doi.org/10.3109/03093649709164551 26. gholizadeh h, abu osman na, lúvíksdóttir ág, eshraghi a, kamyab m, wan abas ab. a new approach for the pistoning measurement in transtibial prosthesis. prosthet orthot int. 2011; 35(4):360–4. https://doi.org/10.1177/0309364611423130 27. gholizadeh h, abu osman na, kamyab m, eshraghi a, lúvíksdóttir ág, wan abas ab. clinical evaluation of two prosthetic suspension systems in a bilateral transtibial amputee. am j phys med rehabil. 2012; 91(10):894–8. doi: 10.1097/phm.0b013e31823c74d7 28. brunelli s, delussu as, paradisi f, pellegrini r, traballesi m. a comparison between the suction suspension system and the hypobaric iceross seal-in® x5 in transtibial amputees. prosthet orthot int. 37(6), 436–444. https://doi.org/10.1177/0309364613476531 29. gholizadeh h, abu osman na, eshraghi a, ali s, arifin n, wan abas ab. evaluation of new suspension system for limb prosthetics. biomed eng online. 2014; 13(1):1. https://doi.org/10.1186/1475-925x-13-1 30. eshraghi a, abu osman na, gholizadeh h, ahmadian j, rahmati b, wan abas ab. development and evaluation of new coupling system for lower limb prostheses with acoustic alarm system. sci rep. 2013; 3,2270. https://doi.org/10.1038/srep02270 31. wirta rw, golbranson fl, randy mason cp, calvo k. analysis of below-knee suspension systems. j rehabil res dev. 1990; 27(4), 385-396. 32. sanders je, nicholson bs, zachariah sg, cassisi dv. testing of elastomeric liners used in limb prosthetics: classification of 15 products by mechanical performance. j rehabil res dev. 2004; 41(2):175. doi: 10.1682/jrrd.2004.02.0175 33. mcgrath mp, gao j, tang j, laszczak p, jiang l, bader d, et al. development of a residuum/socket interface simulator for lower limb prosthetics. proceedings of the institution of mechanical engineers, part h: journal of engineering in medicine. 2017 mar;231(3):235-42. https://doi.org/10.1177/0954411917690764 https://doi.org/10.33137/cpoj.v2i2.32941 https://doi.org/10.1080/17461550500069612 https://doi.org/10.1177/0309364611431625 https://doi.org/10.1007/bf00401811 https://doi.org/10.1016/j.apmr.2011.05.019 http://hdl.handle.net/1853/22055 https://doi.org/10.1080/03093640108726605 https://doi.org/10.3109/03093649309164351 https://doi.org/10.1016/j.clinbiomech.2011.07.004 http://dx.doi.org/10.1682/jrrd.2011.11.0221 https://doi.org/10.1177/0309364611434568 https://doi.org/10.3109/03093649709164551 https://doi.org/10.1177/0309364611423130 https://doi.org/10.1177/0309364613476531 https://doi.org/10.1186/1475-925x-13-1 https://doi.org/10.1038/srep02270 https://doi.org/10.1177/0954411917690764 söderberg b, guerra g, fagerstrom t, permpool k, phaipool s. the söderberg socket 2.0: a technical note. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.3. https://doi.org/10.33137/cpoj.v2i2.33505 issn: 2561-987x volume 2, issue 2 2019 (online) technical note all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). https://doi.org/10.33137/cpoj.v2i2.33505 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation 1 open access the söderberg socket 2.0 volume 2, issue 2, article no.3, 2019 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index technical note the söderberg socket 2.0: a technical note söderberg b1, guerra g2*, fagerstrom t1, permpool k1,2, phaipool s1,2 1 centre of excellence for prosthetics and orthotics, scandinavian orthopaedic laboratory, bangkok, thailand. 2 sirindhorn school of prosthetics and orthotics, faculty of medicine, siriraj hospital, mahidol university, bangkok, thailand. introduction prosthetic interface, socket technologies and suspension variants have evolved in recent years to allow for a greater adjustability of the prosthesis to the extremity. numerous transtibial prosthesis technologies work to facilitate an improved dynamic fitting or aid the overall function of the individual.1 various modifications to the socket can augment suspension characteristics and even assist gait of the user.2 some companies have focused on utilizing ratcheting technologies to aid in adjustability of the prosthesis socket, such as the boa system (click medical, boa, steamboat springs, colorado, usa). in this same vein, it is equally important to augment the range of motion for individuals with specific seating, cycling, kneeling and walking requirements. trim lines have remained consistent in the literature and exploration of various socket trim lines might offer patient functional improvements. transtibial prosthesis wearers participating in cycling or squatting and seating might benefit from an enhanced knee range of motion. this is also true when sitting down, for example, in a chair or a car seat. traditional transtibial socket trim lines extend the medial and lateral walls proximally over the epicondyles.3 the rationale for doing so is rooted in habits and seldom questioned. higher trim lines of the supra-condylar and patella tendon bearing (ptb) styles were previously justified because of the introduction of the supracondylar suspension and to enhance medial lateral stability. anterior-posterior and medial-lateral trim lines are rigid and encompass the proximal aspect of the socket in the below knee prosthesis. this conventional design has still remained, even if supracondylar and cuff suspension methods have shifted towards vacuum.1 recent transtibial socket clinical guidelines have served to aid the prosthetist decision abstract background: transtibial prosthesis socket trim lines have remained fairly consistent over the past decade, and based on methods such as a supracondylar cuff suspension. however, with vacuum suspension methods, trim lines can change. objective: an objective of this technical note was to inform practitioners how to fabricate a socket in a better way. a step-by-step fabrication guide is provided for the prosthetist. methods: a unilateral transtibial amputee was selected for this technical note. we provide a detailed description of the different steps of fabrication as well as patient feedback. the fabrication involved fabrication of a vacuum socket using pre-preg carbon fiber and anti-bacterial ethylene-vinyl-acetate (eva), as a proximal flexible brim. findings: the properties of eva and pre-preg carbon fiber allow for fabrication of a transtibial socket with a flexible proximal brim. the new design resulted in greater comfort and increased range of motion in the patient studied. the patient subjectively noted enhanced squatting and cycling capabilities while using the updated socket and flexible proximal brim. conclusion: this technical note presented a fabrication guide for a new style of socket and preliminary patient feedback. clinical studies evaluating functional and biomechanical effects of this new socket design are needed. citation söderberg b, guerra g, fagerstrom t, permpool k, phaipool s. the söderberg socket 2.0: a technical note. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.3. https://doi.org/10.33137/cpoj.v 2i2.33505 keywords prosthesis, transtibial amputees, amputation, transtibial socket, prosthetic suspension * corresponding author gary guerra, ph.d. sirindhorn school of prosthetics and orthotics, faculty of medicine, siriraj hospital, mahidol university, bangkok, thailand. email: gary.gue@mahidol.edu orcid: https://orcid.org/0000-0002-0161-4616 doi: https://doi.org/10.33137/cpoj.v2i2.33505 article info received: december 26, 2019 accepted: march 6, 2020 published: march 10, 2020 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v2i2.33505 https://doi.org/10.33137/cpoj.v2i2.33505 mailto:gary.gue@mahidol.edu https://doi.org/10.33137/cpoj.v2i2.33505 söderberg b, guerra g, fagerstrom t, permpool k, phaipool s. the söderberg socket 2.0: a technical note. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.3. https://doi.org/10.33137/cpoj.v2i2.33505 2 cpoj söderberg et al. 2019 the söderberg socket 2.0 making process by offering greatly needed recommendations.4 such as using vacuum suspension as a viable alternative to supracondylar and cuff suspensions. our previous söderberg socket 1.0 research evidenced that a lowered trim line design can mitigate excessive motion at the knee whilst still allowing the epicondyles to travel anteriorly out of the proximal walls during knee flexion.5 in our clinic we have witnessed the success of this socket design for users with recreational lifestyles performing activities such as cycling and hiking. more recently, the initial söderberg socket 1.0 design presented in 2001 has been adjusted, and much of the rigid socket is now replaced with a flexible integrated proximal socket brim and trim line. it has been our clinical experience, that this additional removal of material when combined with elevated vacuum and a reduced trim line, elicits a greater range of knee motion, protects the suspension sleeve from breaking and can afford a shorter residual limb these same benefits. it was the purpose of this technical note to reintroduce an updated version of the söderberg socket design and provide preliminary patient feedback. we questioned whether these updates would be viewed as a useful benefit to a patient with a desire for more range of motion. methodology the patient for the söderberg 2.0 socket is typically a transtibial amputee with a desire for enhanced range of motion during sitting, squatting or cycling or for aesthetic reasons during sitting. patients with a short transtibial residual limb can also potentially benefit from the elevated flexible brim for better suspension. often times the user is already wearing an endoskeletal modular prosthesis with liner and sleeve aided passive suspension. one active male participant was recruited (65 years, 180cm, 87kg) k3 functional level,6 with residual limb length of 29cm mid-patella tendon to distal end of residual limb. the cause of amputation was trauma at age 55 and prior prosthesis socket and experience was with a pin lock suspension, total surface bearing style prosthesis, endoskeletal design and dynamic response foot. this patient had previously expressed a dislike of traditional socket trim lines, especially during daily trail cycling. without objection, he agreed to volunteer for custom fitting of the söderberg 2.0 socket. this single case record was granted approval through policies of the ethical committee at the faculty of medicine, siriraj hospital, mahidol university. our sampling method for this particular study was a convenience sample, and the participant was recruited from our clinic by word of mouth. as the participant was a healthy ambulator with a high functional level and a unique need, he was recruited for the study. moreover, the patient had no other underlying health conditions or activity restrictions which would exclude them from participation. casting and rectification the patient first donned a simplicity tapered pur liner (otto bock, germany), the residuum was covered with protective wrap and bony landmarks were drawn with an indelible marker. the medial and lateral femoral epicondyles were marked, and a trim line across the proximal limb was drawn. an outline of the tibia and fibular head was defined, and any anatomical points of interest were noted for later rectification. the prosthetist performed a routine evaluation of the patient and created a plaster of paris positive cast of the residual limb using a total surface bearing (tsb) technique. we recommend to extend the proximal trim lines of the cast well over the condyles (35cm) as these higher than traditional trim lines provide landmarks which can later be identified during rectification. a two-stage cast was created, firstly, an anterior slab was made to capture the head of the fibula, patella and tibial crest in 30 of knee flexion. this initial flexion permits easier definition of the anatomy of the tibia and patella tendon. secondly, a circumferential plaster wrap was provided to encapsulate limb volume, posterior wall, and the entirety of the limb was cast in 10-20 knee flexion. these varying casting angles are based off of experience and are modifications of previously established stage casting methods. flexion in the first stage allows for capturing the bony aspects of the limb.7 during the second stage of casting it also important to capture the remaining residual muscle activity by asking the patient to contract and relax numerous times. cast rectification was then performed using traditional principles of the tsb prosthesis with pur liner.8 a sketch, as well as illustration of the söderberg socket trim lines is provided in order to give a better understanding of the socket concept in figure 1 and figure 2. figure 1: illustration demonstrating femoral movement within the söderberg socket.5 fabrication and fitting diagnostic (clear check socket) prosthesis fabrication was manufactured using a 12mm thick northplex square sheet (north sea plastics ltd, glasgow, scotland). the socket was aligned using modular componentry, a one-way expulsion valve was added to the socket and patient was fit with vas, knee sleeve, and a pur liner (otto bock, germany) to create vacuum suspension. this suspension was selected based on the need for an improved connection between the residual limb and socket, to reduce volume fluctuations,9 and because of the socket’s less rigid trim lines.10 typical below knee socket designs are higher along the lateral and medial aspects in order to provide medial lateral support around the condyles. the anterior trim line runs along the mid-patella region or slightly below as to not restrict movement. posteriorly, the https://doi.org/10.33137/cpoj.v2i2.33505 söderberg b, guerra g, fagerstrom t, permpool k, phaipool s. the söderberg socket 2.0: a technical note. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.3. https://doi.org/10.33137/cpoj.v2i2.33505 3 cpoj söderberg et al. 2019 the söderberg socket 2.0 trim line allows both hamstring tendons to move freely and travels slightly proximal to the posterior compartment. the previous söderberg design trim lines did not have the added advantage of a flexible proximal brim. at this stage, the patient donned the check socket and trim lines were evaluated and trimmed to provide maximum medio-lateral and rotational stability as well as comfort according to the söderberg 1.0 trim line.5 each patient will present with individual needs, however, we recommend reducing trim lines on the rigid socket approximately 1-2cm. the patient ambulated and was evaluated to confirm socket fit, alignment and patient comfort. the check socket will allow for minor adjustments, though this was not required in this patient. finally, a new circular cast was performed with the patient wearing the check socket to capture the proximal portion of the knee. the check socket, now with extended plaster cast, was filled with plaster and rectified into an updated model. figure 2: images illustrating the anterior, 45° anterior, posterior view as well as lateral views of the sol style positive plaster model. where (a) indicates trim lines for supracondylar suspension, (b) trim line for a ptb type socket with cuff suspension, and (c) trim line for a söderberg type socket. the definitive fabrication was split into two processes; the first being the fabrication of the proximal brim and the second being creation of the distal definitive socket. to do so, an antibacterial ethylene-vinyl-acetate (eva) material (agruquero, madrid, spain) was formed over the proximal part of the updated positive model. this material selfadheres well and leaves no seams after joining. the oven setting temperature for this material was 140º celsius for 10 minutes and model set time was 20 minutes. after the brim was set, it was removed and trimmed to a proper thickness and skived down along the distal areas to allow for a good integration between the layers of carbon fiber. upon completion of the proximal brim, a second process occurred to create the distal portion of the definitive socket. the distal portion was made from multiple layers of preimpregnated with resin (prepreg) carbon fiber. the pregreg carbon fiber must be stored at a temperature of 20°c prior to curing. storing the material at this temperature extends the life of the material to about one year.11 preparation of the positive model for the prepreg requires removal of the proximal brim. a pva bag is then drawn over the model in the same method as in traditional resin lamination. prepreg strips were then individually adhered onto the model, layer by layer, whilst controlling fiber directions to achieve the desired design and strength. a total of 4 layers of carbon fiber were then wrapped circumferentially in an evenly distributed manner. the proximal brim was then placed back onto the model and finally an additional 4 layers of prepreg were wrapped along the brim transition point. this sandwiching allows flexibility of the proximal portion of the socket. the transition from the eva to the carbon fiber will show no ridges as this eva material adheres to the prepreg carbon fiber in the definitive socket uniformly. moreover, a oneway expulsion valve was placed between the model, prepreg and distal socket adapter. a second pva bag was then applied to enable vacuum suction during curing. the socket was then placed in an oven overnight for curing per prepreg manufacturer recommendations (figure 3). initial cutting and trimming of the socket were performed after the device was assembled. the patient donned the device and flexible proximal trim lines as well as alignment were assessed and adjustments made. trim lines were trimmed to permit full range of motion during the clinic visit. the patient returned to daily activities, and over the course of a year, was asked to return to his typical cycling, hiking and rock-climbing activities and to informally record subjective feedback with respects to range of motion, stability and comfort. the patient returned to living abroad, and subjective feedback from the patient was evaluated in person at the clinic a year later. results the new söderberg 2.0 socket technical achievement is in its ability to blend two different materials together in a socket which enhanced user function. subjective feedback was received from the patient in person at the clinic. although terse, feedback was noteworthy and useful, with the patient describing his cycling and daily activities as “enhanced and without restriction in the knee”. the user expressed that they were able to cycle as often as they wished and do so without any discomfort or restriction of motion. on a side note, he also reported that the silicone knee sleeve had lasted longer than with his previous sockets. ta discussion this technical note explored a new socket design using a combination of materials that improved both range of motion and comfort for the transtibial prosthesis user. our technical achievements were seen in the ability to seamlessly integrate two new materials together in a single rigid-flexible socket design. this technique proved beneficial for the patient during activities of daily living. https://doi.org/10.33137/cpoj.v2i2.33505 söderberg b, guerra g, fagerstrom t, permpool k, phaipool s. the söderberg socket 2.0: a technical note. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.3. https://doi.org/10.33137/cpoj.v2i2.33505 4 cpoj söderberg et al. 2019 the söderberg socket 2.0 figure 3: images illustrating the (a) proximal brim over the first layer of prepreg carbon fiber, (b) trimmed version with second layer of prepreg carbon fiber applied and (c) final socket after curing. the previous söderberg socket design does not provide the user with the superior proximal socket comfort and sleeve protection offered in the current socket style. the patient noting increased lifespan of the liner was most likely due to the flexible brim reducing strain on the sleeve, whereas a regular hard socket brim might not have been able to do so. although, outside of the purview of this technical note, a more robust set of research outcome measurements and comparison between traditional sockets could provide further insight. due to a small sample size, care should be taken not to generalize current findings. in addition, this user’s residual limb length was longer than average which might have affected his feedback of the device. in figure 4, we provide an image of the patient fit with the söderberg 2.0 prosthesis. a potential caveat of this socket design is the requirement of costly prepreg technology, however, this material is critical because of the rigid socket’s seamless interweave of the eva flexible brim. prepreg carbon fiber is widely used in p&o clinics and we believe that this technical note demonstrates a new option in manufacturing of prosthetic sockets that can further improve quality of life for the user. the positive subjective results provided by the patient, encourages us to further evaluate the technique and hopefully, with future clinical studies, the söderberg 2.0 socket design will add to available options for the transtibial prosthesis user. figure 4: image of the patient wearing the söderberg 2.0 prosthesis. acknowledgements we wish to thank the patient for his assistance in this technical note. declaration of conflicting interests the authors have no conflicts of interest to declare. ethical approval this single case record was granted approval through policies of the ethical committee at the faculty of medicine, siriraj hospital, mahidol university. author contribution • bengt söderberg, conceived the idea for the project, supported technical aspects and contributed to the writing of the manuscript • teddy fagerstrom, conceived the idea for the project, supported technical aspects and assisted in the writing of the manuscript • gary guerra, supported the technical aspects and contributed to the writing of the manuscript a b c https://doi.org/10.33137/cpoj.v2i2.33505 söderberg b, guerra g, fagerstrom t, permpool k, phaipool s. the söderberg socket 2.0: a technical note. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.3. https://doi.org/10.33137/cpoj.v2i2.33505 5 cpoj söderberg et al. 2019 the söderberg socket 2.0 • kwannate permpool, supported the technical aspects and contributed to the writing of the manuscript • sarawanee phaipool, supported the technical aspects and contributed to the writing of the manuscript sources of support the authors received no financial support or assistance for this research. references 1.safari mr, meier mr. systematic review of effects of current transtibial prosthetic socket designs-part 1: qualitative outcomes. j rehabil res dev 2015; 52: 491–508. http://dx.doi.org/10.1682/jrrd.2014.08.0184 2. kahle jt, klenow td, sampson wj, highsmith mj. the effect of transfemoral interface design on gait speed and risk of falls. technol innov 2016; 18: 167–173. https://doi.org/10.21300/18.2-3.2016.167 3. krajbich ji, pinzur ms, potter bk, stevens pm, editors. atlas of amputations and limb deficiencies: surgical, prosthetic, and rehabilitation principles. lippincott williams & wilkins; 2016. 4.stevens pm, depalma rr, wurdeman sr. transtibial socket design, interface, and suspension. j prosthet orthot 2019; 31: 172–178. doi: 10.1097/jpo.0000000000000219 5.söderberg b. a new trim line concept for trans-tibial amputation prosthetic sockets. prosthet orthot int 2002; 26: 159–162. https://doi.org/10.1080/03093640208726639 6. gailey rs, roach ke, applegate eb, cho b, cunniffe b, licht s, et al. the amputee mobility predictor: an instrument to assess determinants of the lower-limb amputee’s ability to ambulate. arch phys med rehabil 2002; 83: 613–27. https://doi.org/10.1053/apmr.2002.32309 7.staats t, lundt j. the ucla total surface bearing suction below-knee prosthesis. clin prosthetics orthot 1987; 11: 118– 130. 8.gholizadeh h, abu osman n, eshraghi a, et al. transtibial prosthesis suspension systems: systematic review of literature. clin biomech 2014; 29: 87–97. https://doi.org/10.1016/j.clinbiomech.2013.10.013 9.board wj, street gm, caspers c. a comparisson of transtibial suction and vacuum socket condition. prosthet orthot int 2001; 25: 202–209. https://doi.org/10.1080/03093640108726603 10.kahle jt, highsmith mj. transfemoral interfaces with vacuum assisted suspension comparison of gait, balance, and subjective analysis: ischial containment versus brimless. gait posture 2014; 40: 315–20. https://doi.org/10.1016/j.gaitpost.2014.04.206 11. morgan p. carbon fibers and their composites. crc press; 2005. https://doi.org/10.1201/9781420028744 https://doi.org/10.33137/cpoj.v2i2.33505 http://dx.doi.org/10.1682/jrrd.2014.08.0184 https://doi.org/10.21300/18.2-3.2016.167 https://doi.org/10.1080/03093640208726639 https://doi.org/10.1053/apmr.2002.32309 https://doi.org/10.1016/j.clinbiomech.2013.10.013 https://doi.org/10.1080/03093640108726603 https://doi.org/10.1016/j.gaitpost.2014.04.206 https://doi.org/10.1201/9781420028744 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives miller t.a, wurdeman s. value and applicability of large administrative healthcare databases in prosthetics and orthotics outcomes research. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.4. https://doi.org/10.33137/cpoj.v4i2.35958 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.35958 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 miller ta, wurdeman s. value and applicability of large administrative healthcare databases in prosthetics and orthotics outcomes research. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.4. https://doi.org/10.33137/cpoj.v4i2.35958 stakeholder perspectives value and applicability of large administrative healthcare databases in prosthetics and orthotics outcomes research miller ta.1,2 *, wurdeman s.1,3 1 department of clinical and scientific affairs, hanger clinic, austin, texas, usa. 2 college of health and human services, university of north carolina at charlotte, charlotte, north carolina, usa. 3 department of biomechanics, the university of nebraska at omaha, omaha, nebraska, usa. introduction health economics is a broad field of study with applications that focus on issues related to efficiency, effectiveness, equity, behavior and, ultimately, the value of healthcare services. the goal of health economics and outcomes research (heor) is to improve healthcare decision making for clinicians, managers, policy makers, payers, and patients. one aspect of heor that often comes to mind are the methods that assess cost and utilization (e.g. costeffectiveness analysis or cea). understanding costs and utilization patterns can help define benefits of certain interventions, improve market access and establish the value of services or devices. however, additional areas of heor such as applications in health technology assessment, health service delivery and process of care, and patient-centered research can also lend themselves to better understanding the value of services or devices.1,2 much of this data can be extracted and analyzed from administrative healthcare data. this paper is meant to provide a stronger understanding of administrative healthcare data analysis, an area that has been scarcely examined within orthotics and prosthetics (o&p) despite the wealth of information available within such data. in the absence of high-value clinical data, the availability and quality of administrative healthcare data could be vital in the generation of evidence for o&p services. several studies have assessed treatment interventions for those who require an ankle foot orthosis or a prosthesis, by using large databases in terms of epidemiology,3,4 clinical outcomes,5 and costs of treatment or utilization.6 practical methods are needed by clinicians and researchers to address questions about the risks, benefits, and costs of interventions that inform the value of o&p health services. while randomized controlled trials (rcts) remain a gold standard to establish efficacy and safety; they are not ideal for discovering effective or efficient treatment or for incorporation of the patient experience into clinical decisionmaking.7 furthermore, conducting double blind rct research is not always possible in o&p, which means our healthcare system lacks a comprehensive understanding of the incorporation of o&p devices into rehabilitation. open access volume 4, issue 2, article no.4. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract the goal of health economics and outcomes research is to improve healthcare decision making. in the absence of high-value clinical data, the availability and quality of administrative healthcare data could be vital in the generation of evidence for orthotics and prosthetics services. the purpose of this article is to provide a stronger understanding of administrative healthcare data analysis, an area that has been scarcely examined within prosthetics and orthotics despite the wealth of information available within such data. examples of common datasets in this arena currently available are provided, as well as an overview of the limitations and advantages of studies utilizing such datasets. citation miller ta, wurdeman s. value and applicability of large administrative healthcare databases in prosthetics and orthotics outcomes research. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.4. https://doi.org/10.33137/cpoj.v4i2.35958 keywords health economics, prosthetics, orthotics, outcomes research, rehabilitation * corresponding author taavy a miller, phd, cpo department of clinical and scientific affairs, hanger clinic, austin, texas, usa. e-mail: tamiller@hanger.com orcid id: https://orcid.org/0000-0001-7117-6124 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.35958 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.35958 mailto:tamiller@hanger.com https://orcid.org/0000-0001-7117-6124 2 miller ta, wurdeman s. value and applicability of large administrative healthcare databases in prosthetics and orthotics outcomes research. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.4. https://doi.org/10.33137/cpoj.v4i2.35958 issn: 2561-987x value and applicability of large administrative healthcare databases miller & wurdeman, 2021 cpoj special s p e c ia l i s s u e real world evidence (rwe) studies, which capture effectiveness, and rcts should be considered complementary to answer important healthcare questions. the use of prosthetic or orthotic devices aims to reduce the negative effects of disability (e.g. loss of work, isolation, and decreased independence) and alleviate burden on the healthcare system by improving treatment of conditions (e.g. stroke, amputation) that often require long-term rehabilitation or interaction with the healthcare system. studies that use administrative health data are another way to generate information that contribute to the knowledge of o&p services. administrative data are real world data that can be leveraged to generate rwe as opposed to highly controlled and selective rcts. administrative data reflect the heterogeneous nature of populations. specifically, claims data (i.e. billing data) or hospital discharge data (e.g. the healthcare cost and utilization project or hcup) are typically referred to as secondary data sources because these data were not collected or generated for current research applications but rather for administrative use. while this may lead to some limitations in available information (e.g. limited functional data), they are often reported as reliable and consistent due to the nature and regulation of billing.8 it is worth noting though that the reliability of billing data is limited by the accuracy or integrity of the input. as more studies use administrative data, it highlights the increasing importance to be meticulous and aware of the data (e.g. diagnosis code, billing codes or lcodes) that are submitted for billing purposes. a wide range of data elements comprise an administrative dataset. there are demographic variables (e.g. gender, race, age) and contextual factors (e.g. region of care, type of insurance), provider information (e.g. physician number), international classification of disease (icd) diagnosis codes, current procedural terminology (cpt), and diagnosis-related group (drg) codes. the year of the data dictates which diagnosis codes are used as icd ninth revision (icd-9) was updated to the tenth revision (icd-10) and implemented for billing in 2015. due to this breadth of information, large administrative databases are appropriate and provide meaningful insight given the correct question, such as questions regarding national patterns of care or to determine resource expenditures. yet, these large databases are not without limitations either. key considerations and applications administrative data are a unique source of information whose advantages and disadvantages for the scope of healthcare research have been extensively discussed.8,9 briefly, a few limitations to be aware of are: conditions (diagnoses) must be diagnosed to be present, diagnosed conditions represent services provided but may not show potential need, conversely diagnosis codes not requiring services may not be recorded on a given claim, presence of a diagnosis does not inform on severity of the condition, and there is limited physiological data (i.e. blood pressure or functional mobility). administrative databases are also often set up to be able to differentiate and characterize different lines of service within healthcare (e.g. services provided through an orthopedic surgeon versus vascular surgeon). unfortunately, currently it is not possible to distinguish services provided by an orthotist/prosthetist versus another healthcare provider as o&p services are not differentiated from durable medical equipment for administrative data purposes. however, there are advantages of studies that employ administrative data that can be leveraged through strong design methods. advantages include validity of the data such as admission dates and procedure codes, systematic collection over time, cost data is reflected (charges or paid amounts), large samples allow for analysis of more rare conditions, and depending on the data it may be linked to other data sources (e.g. medicare data can be linked to the national death index or national surveys).8 because administrative health data contain large numbers of patients over long periods of time, as opposed to cross-sectional databases, they are useful to study disease associations with rare risk factors and heterogeneous populations. specifically, in o&p, there is increasing demand for valuebased evidence from studies that contain larger samples and information about the economic impact of treatment.5,6,10 when considering a research study using administrative data, in addition to the advantages and limitations discussed, it is also important to be aware of different characteristics of these databases. first, it is critical to consider the claims process. health insurance claims data are based on information generated from the billing process for the purpose of payment when a patient utilizes health services. this includes inpatient services, outpatient services, emergency department visits, prescription drug utilization and laboratory utilization (e.g. blood work). once the claim is reviewed by a payer, it is both accepted and paid, or not accepted. therefore, coverage may vary from plan to plan and payer to payer. from the research perspective, often a claims dataset contains data that are adjudicated, meaning it is a complete set of data that represents services covered. for example, in prosthetics, if the office visit does not include a billable event (e.g. an alignment adjustment), then it will not be reflected in the data. however, while the patient maintains insurance coverage on a single plan (e.g. a medicare beneficiary), it is possible to track the patient’s journey from a hospitalization (i.e. inpatient services) to provision of a prosthesis or orthosis (i.e. outpatient services) and gain perspective on the overall utilization or pattern of care. https://doi.org/10.33137/cpoj.v4i2.35958 3 miller ta, wurdeman s. value and applicability of large administrative healthcare databases in prosthetics and orthotics outcomes research. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.4. https://doi.org/10.33137/cpoj.v4i2.35958 issn: 2561-987x value and applicability of large administrative healthcare databases miller & wurdeman, 2021 cpoj special s p e c ia l i s s u e a second critical point to be aware of is the source of the claims. in general, there are two main sources in the us: commercial sources (e.g. private insurance) or noncommercial sources (e.g. medicare or veteran’s health administration). it is important to consider your research question and identify the target population to answer the question. for o&p research, information gleaned from each of the different sources has the potential to inform different areas of care. there are several different databases available that may provide good insight for o&p research, each with specific considerations depending on the research question (table 1). these databases have varying requirements for access and cost. it is critical to have clear questions, transparency, and clarity in defining selection criteria when initiating a study. these decisions will help define which administrative databases will be the best match for the study purposes. conclusion in o&p rehabilitation care, we need to continue to be proactive in heor or risk further trailing behind other areas of healthcare. the way we as a field come together and agree upon how to capture, assess, and communicate value will determine our future as we differentiate ourselves from durable medical equipment. as we continue to be proactive in our investigations of heor we will be able to lead and enhance the assessment and value of o&p interventions, as well as demonstrate positive long-term outcomes for individuals who use o&p devices. call to action administrative data is, in general, a largely unexplored area of research for o&p. there are gaps in our knowledge regarding the health economic impact of o&p services and more evidence is needed on the effectiveness of o&p care. with increased reliance upon claims data from a payer and policy perspective, o&p clinicians and administrative persons need to be cognizant of an increased need for consistent coding across the profession. clinicians and office administrators all play a role through daily work flow by enhancing quality control processes with regards to coding. our industry organizations (e.g.: the american orthotic and prosthetic association and the american academy of orthotists and prosthetists) should take charge to implement standards and quality control processes surrounding coding to be adapted by professionals. the industry organizations should continue to work to separate orthotics and prosthetics from durable medical equipment as this will allow for cleaner claims analysis related to orthotic and prosthetic care. orthotic and prosthetic schools should be teaching the role claims data can play in policy decisions to help drive the value of accurate and specific coding. to address gaps related to clinical practice guidelines and standards of care, communication between o&p providers, various specialists (e.g. surgeons, physiatrist) and physical therapists all involved in patient care is important to continue to optimize and standardize table 1: databases that contain prosthetic and orthotic services and/or patients that may require prosthetic or orthotic devices based on individual condition. dataset type of data geographic area source access medicare billing claims of public program national noncommercial must request access for patient level data but summary data may be public, fees vary medicaid billing claims public program for those with limited income and resources, includes nursing home care state based, varies by state noncommercial must request access per state, fees vary ibm watson (marketscan) billing claims for privately insured individuals, most often through employment national commercial must request access, fees vary iqvia (pharmetrics) billing claims for privately insured individuals, most often through employment national commercial must request access, fees vary veteran’s health administration department of veteran’s affairs data, claims and aggregate data national noncommercial some datasets are publicly available healthcare cost & utilization project (hcup) a family of databases discharge data national and state contains data from both commercial and noncommercial most datasets are publicly available after completing online training, fees may apply https://doi.org/10.33137/cpoj.v4i2.35958 4 miller ta, wurdeman s. value and applicability of large administrative healthcare databases in prosthetics and orthotics outcomes research. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.4. https://doi.org/10.33137/cpoj.v4i2.35958 issn: 2561-987x value and applicability of large administrative healthcare databases miller & wurdeman, 2021 cpoj special s p e c ia l i s s u e clinical practice protocols. improved communication and active roles in billing and coding will in turn help produce effective and reliable databases for heor. acknowledgements none. declaration of conflicting interests the authors declare no conflict of interest. sources of support none. references 1.boone da. the economic value of mobility with a prosthesis. j prosthet orthot. 2019; 31:p32–6. doi: 10.1097/jpo. 0000000000000231 2.kannenberg a, seidinger s. health economics: the perspective of a prosthetic manufacturer. j prosthet orthot. 2019;31:p49–54. doi: 10.1097/jpo.0000000000000234 3.ziegler-graham k, mackenzie ej, ephraim pl, travison tg, brookmeyer r. estimating the prevalence of limb loss in the united states: 2005 to 2050. arch phys med rehabil. 2008; 89. doi: 10.1016/j.apmr.2007.11.005 4.zhu k, lou z, zhou j, ballester n, kong n, parikh p. predicting 30-day hospital readmission with publicly available administrative database. methods inf med. 2015; 54(6):560–7. doi: 10.3414/ me14-02-0017 5.dobson a, el-gamil a, shimer m, davanzo je. economic value of prosthetic services among medicare beneficiaries: a claimsbased retrospective cohort study. mil med. 2016;181(2s):18–24. doi: 10.1186/s12984-018-0406-7 6.miller ta, paul r, forthofer m, wurdeman sr. impact of time to receipt of prosthesis on total healthcare costs 12 months postamputation. am j phys med rehabil. 2020; 99(11). doi: 10.1097/phm.0000000000001473 7.horn sd, dejong g, deutscher d. practice-based evidence research in rehabilitation: an alternative to randomized controlled trials and traditional observational studies. arch phys med rehabil. 2012; 93(8):s127-37. doi: 10.1016/j.apmr.2011.10.031 8.garrison lp, neumann pj, erickson p, marshall d, mullins cd. using real-world data for coverage and payment decisions: the ispor real-world data task force report. value heal. 2007; 10(5):326–35. doi:10.1111/j.1524-4733.2007.00186.x 9.memtsoudis sg. limitations associated with the analysis of data from administrative databases. anesthesiology. 2009;111(2):449. doi: 10.1097/aln.0b013e3181adf739 10.stevens, phillip m., highsmith, m. jason, sutton b. measuring value in the provision of lower-limb prostheses. j prosthet orthot. 2019; 31. doi: 10.1097/jpo.0000000000000232 authors scientific biography taavy miller, phd, cpo, is a research scientist within hanger’s department of clinical and scientific affairs. dr. miller has broad experience working as a certified orthotist/prosthetist at large hospital-based systems and in private practice as well as teaching p&o at the university level. dr. miller holds a doctoral degree in health services research with an emphasis in health economics and epidemiology. her research focuses on health equity, reducing disparities and improving access through the assessment of health outcomes and effectiveness using administrative, clinical and patient reported data. she has published several studies in peer-reviewed journals and presented abstracts at national and international conferences. shane wurdeman, phd, cp, is the director of clinical research within hanger’s department of clinical and scientific affairs. he entered the field of o&p as a technician before transitioning to working as an orthotist/prosthetist and finally into his role as a principal investigator. dr. wurdeman holds a bs in physics, an ms in prosthetics and orthotics, and a phd in biomechanics. he has coauthored more than 40 peer-reviewed manuscripts, published 3 book chapters, and presented more than 100 conference abstracts within the field of orthotic and prosthetic rehabilitation. he is a fellow with distinction of the american academy of orthotists and prosthetists, from whom he was recognized in 2020 with their prestigious academy research award. he currently serves as the research director for the american orthotic and prosthetic association and chair of the center for orthotic and prosthetic learning. he has been supported by private grants as well as government grants from the national institutes of health and department of defense. https://doi.org/10.33137/cpoj.v4i2.35958 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 2 2020 research article bateni h. postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.4. https://doi.org/10.33137/cpoj.v3i2.33804 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v3i2.33804 1 bateni h. postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.4. https://doi.org/10.33137/cpoj.v3i2.33804 research article postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees bateni h.* physical therapy program, school of allied health and communicative disorders, northern illinois university, dekalb, illinois, usa. introduction approximately 185,000 amputations occur in the united states per year, and about 2 million americans currently live with a limb loss.1-3 the incidence of amputations per year ranges from 1.2 to 4.4 per 10,000 with a majority of amputations involving the lower limb.4 falling is dangerous and debilitating, yet common, for individuals with lower extremity amputations.5 nearly 50% of amputees experience an accidental fall within a year of their operation; over 40% of those falls result in serious injury, and over 19% require additional medical attention.6 as the amputee population ages, accidental falls become a greater problem. increased rate of fall, reduced balance confidence, and increased fear of falling are reported following lower extremity amputation.7,8 additionally, people with higher levels of amputation experience a higher rate of incidental falls.7,9 postural steadiness, as measured by quantification of postural sway during quiet standing on a force platform, has open access volume 3, issue 2, article no.4, 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: falls can be detrimental to overall health and quality of life for lower extremity amputees. most previous studies of postural steadiness focus on quantification of time series variables extracted from postural sway signals. while it has been suggested that frequency domain variables can provide more valuable information, few current studies have evaluated postural sway in amputees using frequency domain variables. objective: to determine time and frequency domain variables of postural sway among lower extremity amputees vs. healthy young and older adult controls. methodology: participants were assigned to 3 groups: lower extremity amputation (n=6), healthy young adults (n=10), and healthy older adults (n=10). standing barefoot on a force platform, each individual completed 3 trials of each of 3 standing conditions: eyes open, eyes closed, and standing on a foam balance pad. time and frequency domain variables of postural sway were computed and analyzed. results: comparison of older adults, younger adults, and amputees on the three conditions of standing eyes open, eyes closed, and on foam revealed significant differences between groups. mean mediolateral (ml) sway distance from the center of pressure (cop), total excursions and sway velocity was significantly higher for amputees and older adults when compared to young adults (p<0.05). furthermore, power of sway signal was substantially lower for both amputees and older adults. when compared to that of older adults, postural steadiness of amputees was more affected by the eyes closed condition, whereas older adults’ was more affected when sensory and proprioceptive information was perturbed by standing on foam. conclusion: our findings showed that fall risk is greater in amputees than in young adults without amputation. additionally, amputees may rely more heavily on visual information than proprioceptive information for balance, in contrast to older and young adults without amputation. . article info received: march 5, 2020 accepted: september 5, 2020 published: september 20, 2020 citation bateni h. postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.4. https://doi.org/10.33137/cpoj.v3i 2.33804 keywords amputation, postural balance, amputee, prosthesis, lower limb amputation, postural sway * corresponding author: hamid bateni, phd physical therapy program, school of allied health and communicative disorders, northern illinois university, dekalb, illinois, usa. e-mail: hbateni@niu.edu orcid: https://orcid.org/0000-0001-9083-1817 https://doi.org/10.33137/cpoj.v3i2.33804 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i2.33804 https://doi.org/10.33137/cpoj.v3i2.33804 mailto:hbateni@niu.edu https://orcid.org/0000-0001-9083-1817 2 bateni h. postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.4. https://doi.org/10.33137/cpoj.v3i2.33804 issn: 2561-987x postural sway in lower extremity amputees bateni h. 2020 cpoj been used frequently as a method of assessment of static balance and postural control. postural steadiness may be an indicator of the quality of balance and postural control.10-13 literature has linked time series14,15 and frequency domain16-19 variables of postural sway to balance. additionally, it is reported that state of anxiety and fear of falling impact postural sway.20,21 anxiety and fear of falling are psychological conditions that can lead individuals to avoid participation in activities.7 activity avoidance due to the fear of falling can lead to reduced quality of life related to reduced strength, endurance, and balance, and can increase the risk for further health problems, including falls, in patients with lower extremity amputations.22 while most studies of postural steadiness focus on quantification of time series variables extracted from postural sway signals,23 others have suggested and utilized frequency domain variables of sway in parallel with time series variables to reveal more valuable information.11,12,19 analysis of frequency content of a signal reveals underlying changes that often are not observed in time series. for instance, in the absence of movement, agonist and antagonist muscles may still be actively working against each other. additionally, in the inverted pendulum model, that was introduced by maurer and peterka,24 ankle stiffness and noise may be increased simultaneously. in these cases, time series variables, e.g. velocity and displacement, do not show any changes. power spectral density however, would provide information of the underlying conditions. as a result, it is often suggested that both time and frequency domain variables should be evaluated in assessment of postural steadiness. the purpose of this study was to determine change in both time and frequency domain variables of postural sway among lower extremity amputees as compared to healthy young and older adult controls. methodology following approval of the institutional review board (northern illinois university), a study was conducted to determine impact of lower extremity amputation on time series and frequency domain variables of postural sway. this study included 6 individuals with lower extremity amputation (2 unilateral trans-tibial [utt], 1 bilateral transtibial [btt], 2 unilateral trans-femoral [utf] and 1 unilateral hip disarticulation [uhd]) with the average age of 51 (sd=16) years), 10 healthy young adults (age 25 (sd=1.6) years), and 10 healthy older adults (age 71.7 (sd=5.4) years). amputee participants were included if they met the following criteria: a) were lower extremity amputees with more than one year of experience using a prosthetic limb, b) had a comfortable prosthetic limb about which they had no complaints, c) apart from lower extremity amputation, had no physical or mental disability that could potentially affect their balance, d) could ambulate without any assistance or use of an assistive device, and e) could stand upright independently for at least 10 minutes. individuals with any visual deficits (apart from requiring corrective lenses) or vestibular deficits and those with a history of injury or surgery to the lower extremities within the past 6 months were excluded from the study. healthy young and older adults were recruited if they were able to stand upright independently for at least 10 minutes and ambulate without assistance. those with any physical or mental condition that could potentially impact postural control were excluded. participants were asked to sign a consent form prior to participation in the study. a kistler force platform (kistler co., winterthur, switzerland) was used to collect position data of the center of pressure (cop) at 100 hz. a labview program (national instrument, austin, texas) was developed to collect postural sway data. participants were randomly assigned to three standing conditions: a) eyes open, b) eyes closed and c) standing on airex 2.5” thick foam balance pad (airex corporation, somersworth, nh). the conditions of eyes closed and standing of foam were included to estimate changes in postural steadiness when visual and sensory information are diminished. considering that vestibular, visual, and sensory information are typically relied upon to maintain upright posture, deterioration of any of these sources of information may reveal information regarding our dependency on the lost source. each test condition was repeated three times. test orders were block randomized, with each condition presented once in each block. during the study, participants were instructed to stand straight and static with arms on their sides (bare feet, heels together, 57 degrees of toe-out) on the force platform. data was collected for 35 seconds (fs=100). for the eyes-closed condition, researchers asked each participant to close his or her eyes and confirmed that eyes remained closed throughout the trial. while there were not any specific resting periods implemented between trials, participants were informed prior to the testing that they were welcome to request a rest time if they needed to. additionally, during the trials participants were repeatedly asked if they wanted to rest. several participants asked for the rest during the tests. anteroposterior and mediolateral time series data were filtered through a fourth-order zero phase butterworth lowpass filter with cutoff frequency of 5 hz. the first 8 seconds and last 2 seconds of data were cut off to remove any potential lead-in/lead-out effect. matlab and toolbox release 2012b (mathworks, inc., natick, massachusetts) were used to filter postural sway data and to compute variables of interest. sas statistical software was used to conduct statistical analysis and to compare means between healthy adults and amputees. time and frequency domain variables of postural sway were computed. detailed explanation of computation methods for variables and equations are available in literature.11,12,25-28 mean sway distance which represents the average sway from the mean position of the center of pressure was calculated for n data points as follows: https://doi.org/10.33137/cpoj.v3i2.33804 3 bateni h. postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.4. https://doi.org/10.33137/cpoj.v3i2.33804 issn: 2561-987x postural sway in lower extremity amputees bateni h. 2020 cpoj mean sway distance = 1 n ∑ √ap[n]2 + ml[n]2 similarly, total excursion of sway as the total distance cop travels was computed by summation of distance between two consecutive data points: total excursion of sway = ∑ √(ap[n + 1] − ap[n])2 + (ml[n + 1] − ml[n])2 n−1 n=1 velocity of the sway was calculated by dividing total excursion over the time: 𝑉elocity of the sway = total excursion of sway total time power of sway signal was computed as the integrated area of power spectrum, and 95% power frequency was determined as the point below which 95% of the total power is placed.12 a linear mixed model with the random effects for subjects and subjects × condition was used to compare the means. the least square means for the three groups of amputees/older adults/young adults × condition and their pairwise differences were computed for this model. results comparison of older adults, younger adults, and amputees on the three conditions of standing eyes open, eyes closed, and on foam revealed significant differences between groups. mean mediolateral (ml) sway distance from the cop was significantly increased by both amputation and aging (p<0.0001). tukey-kramer post hoc analysis revealed that amputees’ cop deviated a significantly higher distance from the central point than did cop of young participants (figure 1), particularly with eyes closed (p=0.02). similarly, older adults swayed a greater distance mediolaterally than did young adults (p=0.001). the difference between older adults and amputees however, was not statistically significant, even though this value was higher for older adults. furthermore, the difference in total excursions of sway during static standing was also significantly different between the three groups (amputees, young adults, and older adults) (p<0.0001). post hoc analysis showed greater total excursions among older adults when compared to young adults (p<0.05) (figure 2). when older adults were compared to amputee participants, however, the value of excursions was significantly higher for amputees (p=0.0008) only when participants were standing eyes closed. mean velocity of sway was different between groups (p<0.0001). older adults showed higher velocity of sway when compared to young adults in all conditions of standing, i.e., eyes open (p=0.002), eyes closed (p=0.0005), and standing on foam (p=0.001). while amputees swayed at higher velocity than did young adults, their velocity of sway was still lower than older adults’ in eyes open and standing on foam conditions and slightly higher in eyes closed condition. these differences, however, were not statistically significant. when eyes were closed, amputees showed a substantially higher velocity of sway than did young adults (p=0.0008) (figure 3). velocity of sway also varied based on condition of standing for all groups (p=0.0176). amputees’ sway velocity was greatest with eyes closed, followed by standing on foam, and least with eyes open. these differences in sway velocity for the amputee group were statistically significant only for eyes closed vs. eyes open (p=0.024). this pattern however, was different for older adults. older adults showed their highest velocity of sway when standing on foam. there was no statistically significant difference in sway velocity for older adults with eyes closed vs. eyes open, or eyes closed vs. standing on foam. the difference in velocity of sway was significant, however, when foam standing was compared to eyes open (p=0.0446). resultant power of sway signal was also significantly different between the three groups (amputees, young adults, and older adults) (p=0.0074) and between the three conditions of standing (p=0.025). no significant interaction between groups and conditions of standing was noted. when young and older adults were compared, tukeykramer post hoc analysis showed that older adults demonstrated a higher level of power. although this difference was not significant for the eyes open condition, it was nearly significant for the eyes closed (p=0.05) and significant for standing on foam (p=0.0014) conditions. power of sway signal for the amputee group was higher than for young adults and lower than for older adults under conditions of eyes open, eyes closed and standing on foam. this difference however, was not statistically significant. further analysis of our data showed that the resultant mediolateral 95% power frequency was significantly lower for both amputees and older adults when compared to young adults (p<0.05) for eyes open and eyes closed conditions (figure 4). lower power of amputee and older adults however, was not significant compared to young adults for standing on foam condition. since our amputee population consisted of both young and older adults, we performed a secondary analysis on our data, eliminating data for amputees under the age of 60. we anticipated that this change would lead to a more homogenous sample of amputees who were all older adults. therefore, comparison of amputees with older adults and young adults may be more telling. as a result, the amputee group in our secondary analysis consisted of 3 amputees (age 62 (sd=3.8) years). similar to our previous findings, we noticed that older amputees sway at a significantly higher level with eyes closed than do young adults (p=0.046), but the sway distance, although higher, does not differ substantially when compared to older adults without amputation (p>0.05). furthermore, we noticed that even though older amputees performed significantly higher total excursion of sway when compared to young adults (p=0.001), their total excursion was not substantially https://doi.org/10.33137/cpoj.v3i2.33804 4 bateni h. postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.4. https://doi.org/10.33137/cpoj.v3i2.33804 issn: 2561-987x postural sway in lower extremity amputees bateni h. 2020 cpoj different from older adults in closed-eyes conditions. this latter finding was not in agreement with our original findings. pattern of changes in sway velocity was similar to our original analysis. we noticed that older adults showed higher velocity of sway when compared to young adults in all conditions of standing, i.e., eyes open (p=0.002), eyes closed (p=0.0006), and standing on foam (p=0.002). when eyes were closed, older amputees showed a substantially higher velocity of sway than did young adults (p=0.0013). the difference of sway velocity among older adults and amputee was not statistically significant. figure 1: comparison of mean distance from the mean center of pressure in mediolateral direction during static standing for three different conditions of eyes open, eyes closed, and standing on foam. diamond shape and solid line indicate mean and median of the data respectively. data presented for three groups of amputees (am), older adults (oa) and young adults (ya). asterisks (**) denote statistically significant differences (p<0.05). our secondary analysis for the resultant power of sway signal showed a similar pattern as our original analysis. resultant power of sway was significantly different between the three groups (amputees, young adults, and older adults) (p=0.009) and between the three conditions of standing (p=0.01). older adults demonstrated a higher level of power when compared to young adults. this difference was not statistically significant for the eyes open condition and eyes closed conditions, but significantly higher for older adults when standing on foam (p=0.002). power of sway signal for the older amputee group was higher than for young adults and lower than for older adults under conditions of eyes open, eyes closed and standing on foam. analysis of the resultant mediolateral 95% power frequency showed that this value is significantly lower for both older amputees and older adults without amputation when compared to young adults (p<0.05) for eyes-open and eyes-closed conditions. this difference however, was not statistically significant when participants were standing on foam. figure 2: comparison of total excursion of sway for three different conditions of eyes open, eyes closed, and standing on foam. diamond shape and solid line indicate mean and median of the data respectively. data presented for three groups of amputees (am), older adults (oa) and young adults (ya). asterisks (**) denote statistically significant differences (p<0.05). figure 3: figure depicts mean velocity of sway for three different conditions of eyes open, eyes closed, and standing on foam. diamond shape and solid line indicate mean and median of the data respectively. data presented for three groups of amputees (am), older adults (oa) and young adults (ya). asterisks (**) denote statistically significant differences (p<0.05). note variation of mean velocity when amputees and older adults are compared for the conditions of eyes closed versus standing on foam. we performed an additional analysis on our data by removing the two individuals with hip disarticulation and bilateral transtibial amputation and included only those with unilateral transfemoral and transtibial amputation for analysis. 0 10 20 30 40 eyes open eyes closed standing on foam am amoaamoaya ya yaoa ** ** ** ** ** ** m e a n d is ta n c e o f s w a y in m e d io la te ra l d ir e c ti o n ( m m ) 0 500 1500 2000 3000 am am amoa oa oaya ya ya 1000 2500 ** ** ** ** ** ** t o ta l e x c u rs io n s ( m m ) eyes open eyes closed standing on foam 100 120 am amoaamoa oaya ya ya 0 20 40 60 80 ** ** ** ** ** **** ** m e a n v e lo c it y o f c o p ( m m /s ) eyes open eyes closed standing on foam https://doi.org/10.33137/cpoj.v3i2.33804 5 bateni h. postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.4. https://doi.org/10.33137/cpoj.v3i2.33804 issn: 2561-987x postural sway in lower extremity amputees bateni h. 2020 cpoj figure 4: comparison of 95% mediolateral power frequency of sway signal for three different conditions of eyes open, eyes closed, and standing on foam. diamond shape and solid line indicate mean and median of the data respectively. data presented for three groups of amputees (am), older adults (oa) and young adults (ya). asterisks (**) denote statistically significant differences (p<0.05). considering that static balance is mainly controlled through ankle and hip strategies,29 we attempted to create a more homogenized sample by removing two participants from the sample. we anticipated, unlike other participants, bilateral amputees may not have a chance to compensate for the loss of ankle strategy through the sound limb. although inability to perform hip strategy in individuals with hip disarticulation is yet to be determined, we also excluded this participant to avoid any potential bias. comparison of means and confidence limits for time and frequency domain variables showed almost a similar pattern as previous analysis. when older adults and young adults were compared with amputees, except for resultant power, amputees’ variables were closer to those of older adults than young adults (figure 5). the mean of resultant power, however, was closer to the mean power of young adults than older adults (figure 5e). further analysis showed that participants with amputation swayed at a significantly higher velocity when compared with young adults (p=0.012) during eyes closed condition. on the other hand, amputees swayed at a significantly lower velocity when compared to older adults (p=0.015) during standing on the foam condition. similarly, amputees total excursion of sway was higher than young adults in eyes closed trials (p=0.012) and less than older adults in trials of standing on foam (p=0.015). when power of sway signal during standing on foam condition were compared, amputee participant generated significantly less power during static standing comparing with older adults (p=0.002). table 1: table consists of demographic information on study participants. participants are presented as non-amputees (nam), right/left trans tibial (rtt/ltt), bilateral trans tibial (btt), left trans-femoral (ltf) and left hip disarticulation(lhd). most study participants with amputation was using dynamic response (dr) prosthetic feet. participant gender age height (cm) weight (kg) condition res. limb. length reason prosthetic foot 1 m 26 172 67.1 nam --- 2 m 29 171 60.3 nam --- 3 m 24 181 80 nam --- 4 m 24 188 76.1 nam --- 5 f 25 160 65.2 nam --- 6 f 25 153 58.4 nam --- 7 m 77 172.5 66 nam --- 8 f 72 166.6 68.8 nam --- 9 m 25 184.5 91.1 nam --- 10 m 24 187 75.3 nam --- 11 f 24 167.5 69.5 nam --- 12 f 24 159 68.3 nam --- 13 m 69 172 79.5 nam --- 14 f 68 167 62.9 nam --- 15 m 70 166 78.7 nam --- 16 m 77 174.5 86.9 nam --- 17 f 82 160.5 67.1 nam --- 18 m 65 174.8 104.4 nam --- 19 m 71 177.5 94.1 nam --- 20 f 66 157.6 82.1 nam --- 21 m 30 196 100.5 rtt 10 trauma dr 22 m 58 173.4 101 ltt 16.5 trauma dr 23 m 30 185.5 84.4 ltf 36 trauma dr 24 m 61 177 100.1 ltf 37 disease dr 25 f 60 160.51 84.9 lhd 0 disease dr 26 m 67 182.5 92.1 btt 20r / 25l disease sach discussion it has been documented that mediolateral stability significantly correlates with the risk of falling in older adults.30 winter et al. previously highlighted the importance of mediolateral sway during quiet standing.31,32 it has also been shown that mediolateral sway is increased in fallers when compared to non-fallers.33 our results suggest that lower limb amputation significantly affects postural steadiness. comparison of our finding with young and older adults also revealed important aspects of postural control in lower extremity amputees. to our knowledge, no other studies have compared postural stability of lower extremity amputees against that of young and older adults. our results showed that while older adults swayed mediolaterally more than did amputees, the difference was not statistically significant. both amputees and older adults, however, swayed significantly more than did young adults. 0 2 4 6 8 10 amoa oa oaya ya yaam am ** ** ** ** ** ** eyes open eyes closed standing on foam 9 5 % m e d io la te ra l p o w e r fr e q u e n c y ( h z ) https://doi.org/10.33137/cpoj.v3i2.33804 6 bateni h. postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.4. https://doi.org/10.33137/cpoj.v3i2.33804 issn: 2561-987x postural sway in lower extremity amputees bateni h. 2020 cpoj this variation, coupled with others’ findings relating sway to falls, supports the conclusion that both older adults and lower limb amputees are prone to falling. our study finding is in agreement to those of buckley et al,34 who reported increased sway distance in a group of 6 trans-tibial/transfemoral amputees. similarly, total excursions of the center of pressure was higher for both older adults and amputees. when standing was challenged by a compliant (foam) surface, we noticed greater total excursions of sway in older adults, when compared to other conditions. further analysis of sway velocity augmented this finding. velocity of sway is recognized as one of the most important variables of sway analysis that can determine effects of aging on balance.12 our results showed that older adults and amputees sway at a significantly higher velocity than do young adults (p<0.0001). our post-hoc analysis did not reveal any significant difference in sway velocity between amputees and older adults. we also noted that with both amputees and older adults, the sway velocity increased when the condition was changed from eyes open to either eyes closed or standing on foam. it is particularly interesting, however, that the pattern of velocity is different between amputees and older adults when evaluating the three standing conditions. the two conditions of eyes closed and standing on foam are primarily designed to diminish visual and somatosensory/proprioceptive information, respectively, to the postural control system. it has been well documented and also seen in our own data that loss of any one of these sources of information for postural control leads to an increased sway and sway velocity in static standing.35 in our study, when amputees and older adults were compared, amputees swayed most when their eyes were closed, whereas older adults swayed more when they were standing on foam. amputees’ sway velocity with eyes closed was significantly more than with eyes open (p=0.024); whereas, sway velocity did not increase significantly from eyes open to foam standing (p=0.19). on the other hand, for older adults, increase of sway velocity was significant when eyes open was compared to foam standing (p=0.044), while the increase in sway velocity was not significant when eyes open was compared to eyes closed (p=0.59). both groups had am oa ya mdistx 0 5 10 15 m m conditions aeyes open beyes closed cstanding on foam am oa ya m m 2 0 20 40 60 80 100 power x103 am oa ya m m /s 0 10 20 30 40 50 mvelo am oa ya h z 0 2 4 6 pfreq95 am oa ya m m 0 25 50 75 100 125 totex x10 a b c d e figure 5: graph depicts mean values and 95% confidence limits for amputee group (am), older adults (oa) and young adults (ya). data represents amputee participants with unilateral transtibial and transfemoral amputation (n=4). a: variables presented are mean distance of sway in mediolateral direction (mdistx); b: mean velocity of cop (mvelo); c: total excursions (totex), d: 95% mediolateral power frequency (pfreq95); e: resultant power of sway (power). https://doi.org/10.33137/cpoj.v3i2.33804 7 bateni h. postural sway in lower extremity amputees and older adults may suggest increased fall risk in amputees. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.4. https://doi.org/10.33137/cpoj.v3i2.33804 issn: 2561-987x postural sway in lower extremity amputees bateni h. 2020 cpoj corrected visual acuity of 20/20 with no known sensory deficits or physical or mental conditions that could potentially affect their balance. this may indicate that amputees are more dependent on visual information, whereas older adults are more dependent on somatosensory and proprioceptive information, to control their balance. the increased dependency of lower extremity amputees on visual input is also reported by arifin et al.36,37 in a sample of trans-tibial amputees, although no comparisons were made between amputees and young or older adults in this study. also compared were the resultant mediolateral 95% power frequency among the study participants. the 95% power frequency is an estimate of the extent of the spectral content and indicates the frequency below which 95% of the integrated area of power spectrum resides. more detailed definition and method of calculation is explained elsewhere.12,38 power spectral density is known to indicate the underlying mechanism of postural control.12 therefore, the study suggests that the underlying mechanism of postural control for both amputees and older adults changes when eyes were closed, but not when they were standing on foam. limitations there are several limitations acknowledged with respect to the generalizability of the study results. first, the study involved a small number of amputee participants: 6 individuals with lower extremity amputation and 20 healthy controls. although the findings suggest that amputees have an increased risk for falls and that they may rely heavily on visual input for postural control, replication should be sought with a larger sample. it is to be noted that the original sample included both young and older adults. in the secondary analysis, however, the data of amputees older than 60 years was only included. although this change made the study sample more homogenous, it reduced the sample size even more. additionally, all amputee data was combined, regardless of the level of amputation or, in the case of one participant, bilateral vs. unilateral amputation. as a result, this combination may have affected the results, but the level of this impact is yet to be investigated. considering that in the inverted pendulum model of postural control, as suggested by maurer and peterka,24 postural sway is substantially controlled at the ankles. in fact, in a study of 8 unilateral trans-femoral amputees, hlavackova et al.39 showed that the sound limb is most responsible for sway velocity when compared with the amputated side. in the current study, participants had different levels of amputation with the common characteristics that they were all missing their ankle. nevertheless, further studies with a larger and more homogenous sample would be warranted to compare postural sway data between individuals with lower extremity amputation at different levels. conclusion the results of this study suggest that lower limb amputation significantly affects postural steadiness. additionally, it was noted that mediolateral postural sway and velocity of sway of lower limb amputee participants of this study were slightly less than those values for older adults. furthermore, while both amputees and older adults represent a diminished postural steadiness, older adults’ steadiness is challenged more when standing on the foam, while amputees’ steadiness is more challenged when standing with eyes closed. it appears that when older adults and amputees are compared, most likely older adults are more dependent on their sensory information, while amputees are more dependent on their visual information. acknowledgements the author would like acknowledge the help of ms. lisa blackmer (spt–northern illinois university) for her assistance with manuscript preparation and editorial contributions. the author would like to acknowledge the help of physical therapy students at northern illinois university with data collection in this study. declaration of conflicting interests author do not have any conflict of interest to disclose. sources of support n/a ethical approval this study approved 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bipedal stance in lower limb amputees: new insights using entropy. plos one. 2011;6(5):e19661. doi: 10.1371/journal.pone.0019661 https://doi.org/10.33137/cpoj.v3i2.33804 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 technical / clinical note mcgrath m, davies k.c, gallego a, laszczak p, tang j, zahedi s, moser d. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i1.35213 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.35213 1 mcgrath m, davies k.c, gallego a, laszczak p, tang j, zahedi s, moser d. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i1.35213 technical / clinical note using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics mcgrath m1*, davies k.c1, gallego a1, laszczak p1, tang j2, zahedi s1, moser d1 1blatchford group, unit d antura, bond close, basingstoke, uk. 2school of engineering, faculty of engineering and physical sciences, university of southampton, uk. introduction excessive sweating commonly affects lower limb amputees1 and impacts their daily life.2 increased energy expenditure during everyday activities compared to ablebodied people3 and reduced skin surface area4 for cooling both contribute to this issue. prosthetic liners worn on the residuum can also amplify sweating at the residuum-liner interface, as they have poor thermal conductivity5 and little permeability.6 the socket and residual limb are often considered a single entity with a rigid connection. however, in practice, there is relative movement at this interface,7,8 which sweating can worsen, affecting prosthetic suspension.9 technologies have been developed to regulate residuum temperature or manage perspiration.10–13 one such technology uses perforations in the liner to allow sweat to transfer away from the skin. previous evaluations of this technology have reported higher scores in patient-reported outcome measures,13 fewer skin health problems12,13 and a noticeable reduction in the perspiration on the limb.12,13 due to the inherent heterogeneity and variability of amputees,14 some researchers have emulated the residual limb using simulators and test machines, in lieu of human participants.15,16 these can recreate realistic interface mechanics in prosthetic sockets,17–20 in a highly open access volume 4, issue 1, article no.3. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: lab-based simulators can help to reduce variability in prosthetics research. however, they have not yet been used to investigate the effects of sweating at the residuum-liner interface. this work sought to create and validate a simulator to replicate the mechanics of residual limb perspiration. the developed apparatus was used to assess the effects of perspiration and different liner designs. methodology: by scanning a cast, an artificial residuum was manufactured using a 3d-printed, transtibial bone model encased in silicone, moulded with pores. the pores allowed water to emit from the residuum surface, simulating sweating. dry and sweating cyclic tests were performed by applying compressive and tensile loading, while measuring the displacement of the residuum relative to the socket. tests were conducted using standard and perforated liners. findings: although maximum displacement varied between test setups, its variance was low (coefficient of variation <1%) and consistent between dry tests. for unperforated liners, sweating increased the standard deviation of maximum displacement approximately threefold (0.04mm v 0.12mm, p<0.001). however, with the perforated liner, sweating had little effect on standard deviation compared to dry tests (0.04mm v 0.04mm, p=0.497). conclusions: the test apparatus was effective at simulating the effect of perspiration at the residual limb. moisture at the skin-liner interface can lead to inconsistent mechanics. perforated liners help to remove sweat from the skin-liner interface, thereby mitigating these effects. article info received: december 4, 2020 accepted: march 10, 2021 published: march 19, 2021 citation mcgrath m, davies k.c, gallego a, laszczak p, tang j, zahedi s, moser d. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i 1.35213 keywords sweating, residual limb, socket interface, simulator, lower limb prosthetics, amputation * corresponding author: dr. michael mcgrath, phd research scientist–clinical evidence blatchford group, unit d antura, bond close, basingstoke, rg24 8pz, united kingdom. email: mike.mcgrath@blatchford.co.uk orcid: https://orcid.org/0000-0003-0195-970x https://doi.org/10.33137/cpoj.v4i1.35213 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.35213 https://doi.org/10.33137/cpoj.v4i1.35213 mailto:mike.mcgrath@blatchford.co.uk https://orcid.org/0000-0003-0195-970x 2 mcgrath m, davies k.c, gallego a, laszczak p, tang j, zahedi s, moser d. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i1.35213 issn: 2561-987x a sweating residuum/socket interface simulator mcgrath et al. 2021 cpoj reproducible and repeatable manner. these methods have not yet been used to examine effects of perspiration at the residuum-liner interface. objectives this research sought to achieve the following objectives; design, construct and evaluate a test apparatus to recreate the impact of sweat at the residuum-liner interface, identify how displacement during loading is affected by the presence of moisture, and evaluate the efficacy of a liner designed for perspiration management. methodology manufacture this research followed a similar artificial residuum manufacturing method to mcgrath et al.17 a transtibial residuum cast was scanned and a pin-lock check socket was created. a transtibial bone model of an extended knee was also scanned so that the bones and residuum could be scaled in size to match one another. the scaled bone model and two halves of a negative residuum mould were created using additive manufacture. the soft tissue was simulated by moulding silicone (smooth-on, inc., pa, usa; density = 1.08 g/cm3) around the bone model. during moulding, 3mm diameter plastic straws were used to create pores in the silicone, evenly spaced along the length and around the circumference, with one at the distal end (figure 1a). the 3mm diameter was the minimum that could be consistently 3d printed. water was applied, via a syringe and rubber tubing, into the proximal opening between silicone and bone. once in the central canal, applying compression forced the water through the pores to the outer surface. the proximal hole was sealed with the rubber tubing in place, using a silicone adhesive. the residuum and its cross-section are shown in figures 1b and 1c, respectively. a female pyramid tube adaptor was fixed to the proximal end of the bone model allowing rigid attachment to a universal test machine (lr10k plusi, lloyd instruments, uk – figure 1d). protocol the residuum was fitted with a pin-lock liner (comfort linerii, blatchford ltd, uk) and attached to the check socket. since this simulator sought to mimic both stance and swing phase, for simplicity, it was vertically-oriented on the test machine (figure 1d). figure 1: (a) the 3d printed bones held in place in the negative residuum mould with 3mm straws to create “pores” (b) the moulded silicone artificial residuum with pores visible along its surface (c) an annotated cross-section diagram of the artificial residuum (d) the artificial residuum set up on the test machine. syringe artificial residuum liner check socket lock (d) (a) (b) (c) 3d printed bones silicone “pores” water in https://doi.org/10.33137/cpoj.v4i1.35213 3 mcgrath m, davies k.c, gallego a, laszczak p, tang j, zahedi s, moser d. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i1.35213 issn: 2561-987x a sweating residuum/socket interface simulator mcgrath et al. 2021 cpoj tests were load controlled. a single cycle increased to a maximum 800n compression, reversed to a maximum 100n tension, then returned to 0n. 800n is a typical maximum force applied by an adult of approximately 7080kg during walking.21 100n is a liberal estimate of the combined peak gravitational and centripetal forces on the limb during swing phase. the outcome measurement was displacement, recorded by the actuator of the test machine. the measurement was zeroed before any compression occurred, so the output reflected the change in displacement of the proximal attachment of the residual limb, from its initial position, due to the loading pattern. for sweating tests, 20ml of water was added, based on an approximation calculated from reported amputee sweating rates22 and the residuum surface area. following each sweating test, the liner was removed to note the quantity of water remaining inside and the residuum was heated for eight hours in an oven at 40°c to ensure the evaporation of any residual water. the order of testing for dry and sweating tests was randomised. repeatability tests were 50 seconds long, performing 50 cycles at a frequency of 1hz to simulate a 120 steps per minute walking cadence. of typical walking bouts, 75% consist of fewer than 40 steps and 60% last under 30 seconds,23 so each simulator test would represent the majority of these bouts. reproducibility it was possible that deconstruction/reassembly of the setup would create differences in the exact fit of the liner on the residuum or the residuum in the socket. this replicates the real-world conditions of doffing and donning a prosthesis day-to-day. three dry tests of 50 cycles each were performed and the simulator was deconstructed and reconstructed between tests, to quantify this effect. liners the protocol was used to evaluate perforated liners (silcare breathe lockingiii, blatchford ltd, uk). these liners have perforations along the length (columns of 150), circumference (eight columns) and at the distal end (60) to allow sweat removal. the perforated and unperforated liners were made with the same silicone, the same fabric (polyamide and lycra) and the same thickness profile (7mm distally, 2.9mm proximally), so the only difference was the perforations. the order of liner testing was random. data processing the first five recorded cycles of each test were excluded from data analysis to account for any human error during setup e.g. the pin ratcheting further into the lock. the remaining 45 cycles were checked to ensure at least 780n compression. displacement values were compared between tests by magnitude (mean values) and variability (standard deviation (sd), coefficient of variation (cv)). shapiro-wilk tests evaluated data normality. the brownforsythe test for homogeneity of variance determined whether datasets had equal variances. this test was chosen for its robustness with non-normal distributions. for normal data, t-tests compared mean displacements. for non-parametric data, wilcoxon tests were used if group variances were homogenous, otherwise kruskal-wallis tests were employed. statistical significance was defined as p≤0.05. results reproducibility hysteresis curves for the three reproducibility tests are shown in figure 2. measurements showed that absolute displacement was sensitive to the simulator setup. maximum values for each repetition (mean±sd; 5.73±0.04mm, 4.85±0.04mm, 5.78±0.04mm, respectively) showed a statistically significant difference (p<0.001). minimum values for each test (-0.07±0.13mm, -0.86±0.10 mm, -0.95±0.06mm, respectively) also showed a statistically significant difference (p<0.001). repeatability the cvs for maximum displacements were 0.7%, 0.8% and 0.6% for repetitions 1, 2 and 3, respectively. the brownforsythe test indicated no significant difference in the variances of these tests (p=0.42). variability of maximum displacement was chosen to compare between further tests. sweating figure 3a and 3b show the hysteresis curves of a dry test and a sweating test for a standard liner. maximum displacement increased with each cycle of the sweating test. the sd of maximum displacement of the sweating test (0.12mm) was significantly higher than for the dry test (0.04mm, p<0.001). after the sweating test approximately 50% of the water applied was poured out from the bottom of the liner. this did not include any water that may have been remaining on the artificial residuum or in its pores. liners figure 4a and 4b show the differences in hysteresis curves between a dry test and a sweating test for a perforated liner. the sweating test retained a high degree of repeatability (cv=0.7%), comparable to the dry tests. the variability of https://doi.org/10.33137/cpoj.v4i1.35213 4 mcgrath m, davies k.c, gallego a, laszczak p, tang j, zahedi s, moser d. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i1.35213 issn: 2561-987x a sweating residuum/socket interface simulator mcgrath et al. 2021 cpoj the sweating test (sd=0.04mm) and the dry test (sd=0.04mm) were not significantly different (p=0.497). figure 4c, shows the interquartile ranges for all tests, normalised by medians. the variability of the sweating test with the perforated liner (sd = 0.04mm) was significantly less than with the standard liner (sd=0.12mm, p<0.001). after the test, the volume of water poured out from the liner was approximately 5% of the volume originally applied. this did not include any water that may have been (a) remaining on the surface of the residuum, (b) in its pores, (c) absorbed by the outer liner fabric, or (d) expelled from the socket at the distal end, via the lock, which could not be accurately quantified. figure 2: (top) the displacement v load curves for the three reproducibility tests. positive load and displacement indicate compression, negative load and displacement indicate tension. n.b. not all curves pass through the origin due to the exclusion of the first five cycles. (bottom) the maximum displacements of each of the cycles, for each reproducibility test. the variability of these maxima, within each test, is annotated. -1 0 1 2 3 4 5 6 7 -200 0 200 400 600 800 1000 d is p la c e m e n t (m m ) load (n) reproducibility tests repetition 1 repetition 2 repetition 3 4 4.5 5 5.5 6 6.5 7 700 720 740 760 780 800 820 840 860 880 900 d is p la c e m e n t (m m ) load (n) maxima only variability of maxima (repetition 2) variability of maxima (repetition 3) variability of maxima (repetition 1) maxima only https://doi.org/10.33137/cpoj.v4i1.35213 5 mcgrath m, davies k.c, gallego a, laszczak p, tang j, zahedi s, moser d. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i1.35213 issn: 2561-987x a sweating residuum/socket interface simulator mcgrath et al. 2021 cpoj figure 4: (a) the hysteresis curve of a dry test with the perforated liner (b) the hysteresis curve of a sweating test with the perforated liner (c) a box-and-whisker plot of the maximum displacement values from the dry and sweating tests with the standard and perforated liners (normalised by median). the box indicates the interquartile range and the whiskers indicate the maximum and minimum values. the lines at the top of the plot show where comparisons of variability were made. asterisks (*) indicate a significant difference (p<0.05) in variance between tests. -1 0 1 2 3 4 5 6 7 -200 0 200 400 600 800 1000 d is p la c e m e n t (m m ) load (n) dry test (perforated liner)(a) -1 0 1 2 3 4 5 6 7 -200 0 200 400 600 800 1000 d is p la c e m e n t (m m ) load (n) sweating test (perforated liner)(b) -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 standard liner dry test standard liner sweating test perforated liner dry test perforated liner sweating test d if fe re n c e f ro m t e s t m e d ia n variability of maximum compression values by test(c) * n.s. * n.s. * n.s. figure 3: (a) the hysteresis curve of a dry test with the standard liner (b) the hysteresis curve of a ‘sweating’ test with the standard liner. -1 0 1 2 3 4 5 6 7 -200 0 200 400 600 800 1000 d is p la c e m e n t (m m ) load (n) dry test(a) -1 0 1 2 3 4 5 6 7 -200 0 200 400 600 800 1000 d is p la c e m e n t (m m ) load (n) sweating test(b) https://doi.org/10.33137/cpoj.v4i1.35213 6 mcgrath m, davies k.c, gallego a, laszczak p, tang j, zahedi s, moser d. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i1.35213 issn: 2561-987x a sweating residuum/socket interface simulator mcgrath et al. 2021 cpoj discussion a simulator was successfully constructed to mimic the interface dynamics of a sweating residual limb. tests demonstrated that moisture at the residuum-liner interface leads to greater variability in the displacement of the residual limb, relative to the socket, when loaded to replicate walking. when a perforated prosthetic liner was used to allow moisture to transport away from the interface, the variability of displacement was equivalent to that of dry tests, under the same walking load pattern. for simplicity and the constraints of the test equipment, the simulator was mounted vertically on the test machine. while axial displacement is the largest in magnitude7,24 and widest-researched,20,25–28 the other five degrees-of-freedom (anterior-posterior and medial-lateral translation, as well as rotation about each of the three axes), are also likely to be affected.7,28 regardless, the results demonstrated a sufficient mechanism to identify the influence of perspiration at the liner interface. in terms of repeatability, the simulator had cvs<1% between strides. even between reproducibility tests, which were statistically different, differences in maximum displacement were approximately 1mm, and therefore unlikely to be perceptible by a wearer. consistent suspension is important with suspension method25–30 and socket fit/design31–34 affecting prosthetic performance. the effect of sweating was illustrated in figure 3. variability (sd) increased approximately threefold (p<0.001); maximum displacement increasing with each progressive cycle. this movement contributes to skin damage35 and explains why sweat affects gait quality.9 a review of gait stability in non-amputees observed that inconsistent gait parameters were the strongest distinguishing factor between fallers and non-fallers,36 with similar observations reported for transtibial amputees.37 the effect of using a perforated liner was investigated (figure 4). while variability increased 194% with the standard liner during sweating tests, there was no significant difference in variability of the dry and sweating tests with the perforated liner (p=0.497). notably, even when sweating, the perforated liner retained the consistent mechanics of a dry interface. limitations the scope of the simulator was to develop a method to distribute liquid across the residuum-liner interface. this simplified some characteristics of the residual limb, such as the size and distribution of sweat pores and the heterogeneity of the soft tissue. nor was it designed to account for the rate of sweat production; the liquid was present from the first loading cycle. similarly, other conditions associated with sweating (e.g. increased temperature) were not considered in the design. there were limitations of this simplified design. by adding the liquid at the top there was no way to ensure that all of the water had been pushed to the surface. furthermore, during the ‘sweating’ test with the perforated liner, water was observed being emitted from the perforations but was not evenly across the liner, perhaps implying that the perspiration was not distributed evenly across the residuum surface. the variable pore length due to residuum geometry and the effect of gravity likely had an impact. another potential limitation was the coefficient of friction (cf) between the materials used. the cf between human skin and silicone is between 0.35 and 1.16, with a mean value of 0.6138. the cf of the silicone used to create the artificial residuum is not reported by the manufacturer. however, by keeping it constant between tests, relative comparisons can be made. an alternative might have been to perform in-vitro experiments with animal specimens. the advantages would have been closer approximations of the mechanical and frictional properties of human tissue. the drawbacks would have been losing the geometry of a residual limb in a socket and less control over the quantity of liquid at the interface. finally, it should be noted that these same results may not be generalizable to other liner designs. differences in the size, profile and distribution of perforations, as well as liner profile and the external fabric may all have an effect on the efficiency of sweat removal. conclusion in conclusion, the test apparatus was effective at simulating perspiration at the residual limb with reproducible results. perforated liners remove perspiration from the residuumliner interface, helping to maintain consistent mechanical behaviour. minimising unwanted movement reduces the risk of soft tissue injury. acknowledgements the authors wish to thank simon jarvis, the engineer who ran the universal test machine for the experiments in this research. declaration of conflicting interests some of the authors are full time employees of the manufacturer of the prosthetic liners evaluated in this study author contribution michael mcgrath: conceptualisation, manufacturer, data collection, data analysis, writing original, review and editing https://doi.org/10.33137/cpoj.v4i1.35213 7 mcgrath m, davies k.c, gallego a, laszczak p, tang j, zahedi s, moser d. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i1.35213 issn: 2561-987x a sweating residuum/socket interface simulator mcgrath et al. 2021 cpoj kc davies: writing original, review and editing ana gallego: conceptualisation, manufacturer, data collection, review and editing piotr laszczak: conceptualisation, review and editing jinghua tang: review and editing saeed zahedi: review and editing david moser: review and editing sources of support some of the authors are employees of blatchford products ltd. ethical approval ethical approval was not needed for this study. references 1.ghoseiri k, safari mr. prevalence of heat and perspiration discomfort inside prostheses: literature review. j rehabil res dev. 2014;51:855. doi: 10.1682/jrrd.2013.06.0133 2.hagberg k, brånemark r. consequences of non-vascular transfemoral amputation: a survey of quality of life, prosthetic use and problems. prosthet orthot int. 2001;25:186–94. doi: 10.1080/ 03093640108726601 3. gailey rs, wenger ma, raya m, kirk n, erbs k, spyropoulos p, et al. energy expenditure of trans-tibial amputees during ambulation at self-selected pace. prosthet orthot int. 1994;18:84– 91. doi: 10.3109/03093649409164389 4.seymour r. prosthetics and orthotics: lower limb and spinal. philadelphia, pa, usa: lippincott williams & wilkins; 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prosthetics & orthotics journal. 2021;volume 4, issue 1, no.3. https://doi.org/10.33137/cpoj.v4i1.35213 issn: 2561-987x a sweating residuum/socket interface simulator mcgrath et al. 2021 cpoj 23.orendurff ms, schoen ja, bernatz gc, segal ad. how humans walk: bout duration, steps per bout, and rest duration. j rehabil res dev. 2008;45:1077. doi: 10.1682/jrrd.2007.11.0197 24.swanson ec, mclean jb, allyn kj, redd cb, sanders je. instrumented socket inserts for sensing interaction at the limbsocket interface. med eng phys. 2018;51:111–8. doi: 10.1016/ j.medengphy.2017.11.006 25.darter bj, sinitski k, wilken jm. axial bone-socket displacement for persons with a traumatic transtibial amputation: the effect of elevated vacuum suspension at progressive bodyweight loads. prosthet orthot int. 2016;40:552–7. doi: 10.1177/0309364615605372 26.gerschutz mj, hayne ml, colvin jm, denune ja. dynamic effectiveness evaluation of elevated vacuum suspension. j prosthet orthot. 2015;27:161–5. doi: 10.1097/jpo. 0000000000000077 27.klute gk, berge js, biggs w, pongnumkul s, popovic z, curless b. vacuum-assisted socket suspension compared with pin suspension for lower extremity amputees: effect on fit, activity, and limb volume. arch phys med rehabil. 2011;92:1570–1575 28.board wj, street gm, caspers c. a comparison of trans-tibial amputee suction and vacuum socket conditions. prosthet orthot int. 2001;25:202–209. doi: 10.1080/03093640108726603 29.kahle jt, highsmith mj. transfemoral sockets with vacuumassisted suspension comparison of hip kinematics, socket position, contact pressure, and preference: ischial containment versus brimless. j rehabil res dev. 2013;50:1241. doi: 10.1682/jrrd. 2013.01.0003 30.brunelli s, delussu as, paradisi f, pellegrini r, traballesi m. a comparison between the suction suspension system and the hypobaric iceross seal-in® x5 in transtibial amputees. prosthet orthot int. 2013;37:436–44. doi: 10.1177/0309364613476531 31.yiğiter k, şener g, bayar k. comparison of the effects of patellar tendon bearing and total surface bearing sockets on prosthetic fitting and rehabilitation. prosthet orthot int. 2002;26:206–12. doi: 10.1080/03093640208726649 32.eshraghi a, osman naa, karimi mt, gholizadeh h, ali s, abas wabw. quantitative and qualitative comparison of a new prosthetic suspension system with two existing suspension systems for lower limb amputees. am j phys med rehabil. 2012;91:1028–38. doi: 10.1097/phm.0b013e318269d82a 33.gholizadeh h, abu osman na, eshraghi a, ali s, wan abas wab, pirouzi g. transtibial prosthetic suspension: less pistoning versus easy donning and doffing. j rehabil res dev. 2012;49:1321–30. doi: 10.1682/jrrd.2011.11.0221 34.convery p, murray k. ultrasound study of the motion of the residual femur within a trans-femoral socket during gait. prosthet orthot int. 2000;24:226–32. doi: 10.1080/03093640008726552 35.dudek nl, marks mb, marshall sc, chardon jp. dermatologic conditions associated with use of a lower-extremity prosthesis. arch phys med rehabil. 2005;86:659–63. doi: 10.1016/j.apmr. 2004.09.003 36.hamacher d, singh n, van dieen j, heller m, taylor w. kinematic measures for assessing gait stability in elderly individuals: a systematic review. j r soc interface. 2011;8:1682– 98. doi: 10.1098/rsif.2011.0416 37.hordacre bg, barr c, patritti bl, crotty m. assessing gait variability in transtibial amputee fallers based on spatial-temporal gait parameters normalized for walking speed. arch phys med rehabil. 2015;96:1162–5. doi: 10.1016/j.apmr.2014.11.015 38.zhang m, mak a. in vivo friction properties of human skin. prosthet orthot int. 1999;23:135–41. doi: 10.3109/ 03093649909071625 manufacturers’ documentation i) https://www.ametektest.com//media/ametektest/download_links/data_dual_column_test_stand s_lr10kplus_data_sheet_english.pdf ii) https://www.blatchfordus.com/products/comfort-liner/ iii) https://www.blatchfordus.com/products/silcare-breathe-lockingliner/ https://doi.org/10.33137/cpoj.v4i1.35213 https://www.ametektest.com/-/media/ametektest/download_links/data_dual_column_test_stands_lr10kplus_data_sheet_english.pdf https://www.ametektest.com/-/media/ametektest/download_links/data_dual_column_test_stands_lr10kplus_data_sheet_english.pdf https://www.ametektest.com/-/media/ametektest/download_links/data_dual_column_test_stands_lr10kplus_data_sheet_english.pdf https://www.blatchfordus.com/products/comfort-liner/ https://www.blatchfordus.com/products/silcare-breathe-locking-liner/ https://www.blatchfordus.com/products/silcare-breathe-locking-liner/ all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives highsmith mj, fantini cm, smith dg. contemplating health economics, coding and reimbursement in orthotics, prosthetics and pedorthics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.5. https://doi.org/10.33137/cpoj.v4i2.36125 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.36125 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 highsmith mj, fantini cm, smith dg. contemplating health economics, coding and reimbursement in orthotics, prosthetics and pedorthics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.5. https://doi.org/10.33137/cpoj.v4i2.36125 stakeholder perspectives contemplating health economics, coding and reimbursement in orthotics, prosthetics and pedorthics highsmith mj1,2*, fantini cm2, smith dg3,4 1 school of physical therapy & rehabilitation sciences, morsani college of medicine, university of south florida, tampa, florida, usa. 2 u.s. department of veterans affairs, rehabilitation & prosthetics services, washington, usa. 3 department of physical medicine and rehabilitation, uniformed university of the health sciences, bethesda, maryland, usa. 4 department of orthopaedics and sports medicine, university of washington, seattle, washington, usa. economic science in orthotics, prosthetics and pedorthics health economics in orthotic, prosthetic and pedorthics (o&p) may be thought of as maximizing o&p related rehabilitation for those using these services given limited available resources. a body of literature exists on the subject of healthcare economics in o&p. included in this body of work is a state of the science conference proceeding from the american academy of orthotists and prosthetists (aaopo&p’s professional association in the u.s.) which includes twelve articles.1 contributions in this work include projects commissioned by the american orthotic and prosthetic association (aopao&p’s trade association in the u.s.) such as a report comparing costs and outcomes in medicare recipients receiving prosthetic care with those who did not receive prosthetic care and also comparing those of selected orthotic care.2 additionally, building upon previously published clinical literature on microprocessor knee technologies for patients with transfemoral amputation which studied topics such as function, quality of life, safety and other clinical issues,3 aopa commissioned a comprehensive economic analysis on the cost effectiveness of microprocessor knee systems compared to alternatives.4 this review concluded that mpk systems represent good, or potentially superior, value for money to comparable interventions in other healthcare sectors including total knee arthroplasty or implantable cardioverter defibrillators as cited examples.4 among many positive benefits, the state of the science proceeding and health economic o&p literature referenced thus far succeeded in: 1. raising awareness of health economic issues in o&p. 2. pulling together o&p’s body of knowledge in the health economic space. open access volume 4, issue 2, article no.5. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract reimbursement to u.s. healthcare service providers is largely transitioning from fee for service to fee for value for those clinicians who code using current procedural terminology and through their coding, describe their professional services. the orthotic, prosthetic and pedorthic profession (o&p), currently codes using a system that describes the devices they evaluate for, fabricate, fit and maintain and their professional services are incorporated into their codes. these o&p codes, in contrast to those for other healthcare disciplines, are predominantly product based rather than service based, focusing on product features and function more than clinical service. this editorial manuscript provides a brief overview of the system the us o&p profession uses currently, particularly in the context of other healthcare professions transitioning to value based coding and reimbursement and culminates in a call to action for the profession to academically consider the strengths and weaknesses of the current system relative to alternative systems. citation highsmith mj, fantini cm, smith dg. contemplating health economics, coding and reimbursement in orthotics, prosthetics and pedorthics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.5. https://doi.org/10.33137/cpoj.v4i2.36125 keywords coding, economics, fee for service, orthotics, prosthetics, reimbursement * corresponding author m. jason highsmith, phd, dpt, cp, faaop school of physical therapy & rehabilitation sciences, morsani college of medicine, university of south florida. florida, usa. e-mail: mhighsmi@usf.edu orcid id: https://orcid.org/0000-0001-8361-7345 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.36125 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.36125 mailto:mhighsmi@usf.edu https://orcid.org/0000-0001-8361-7345 2 highsmith mj, fantini cm, smith dg. contemplating health economics, coding and reimbursement in orthotics, prosthetics and pedorthics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.5. https://doi.org/10.33137/cpoj.v4i2.36125 issn: 2561-987x contemplating health economics, coding and reimbursement highsmith et al., 2021 cpoj special s p e c ia l i s s u e 3. identifying conclusions, evidence statements, recommendations, strengths, weaknesses and knowledge gaps in o&p health economic science. 4. providing foundational, economic methodologies that may be used in o&p research. 5. initiating a call to action for the o&p profession’s research community to work toward adding economic analyses to ongoing and future research. the aforementioned work also led o&p thought leaders to share and learn from healthcare disciplines outside of o&p to examine future directions relating to payment (i.e. reimbursement) structure. the purposes of this editorial are to point out a collection of health economic work in o&p, increase awareness of reimbursement changes taking place outside of o&p and to serve as a catalyst for conversation within the o&p profession by proposing a call to action related to potential next steps in advancing o&p’s coding and reimbursement conversation. reimbursement changes taking place outside of o&p in 1965, the u.s. congress created medicare under title xviii of the social security act.5 in 1966, the american medical association(ama), in concert with other specialty organizations, developed the iterative, current procedural terminology (cpt) system. the cpt system was developed to provide standardized, uniform language for describing medical procedures and services and initially had no relationship with reimbursement.5 the ama reviews and updates cpt codes annually. healthcare innovation since development of the cpt code system has necessitated updates numerous times across the decades. the health insurance portability and accountability act (hipaa) of 1996, required the department of health and human services to name standards and code sets for electronic transactions of health information. this catalyzed further assessment of the cpt system, expanding beyond the reporting of procedures and services and into the reporting of pay for performance measures. the cpt coding system is the basis for service provider reimbursement when used with a relative value modifier.5 a detailed history of coding systems is beyond the scope of this manuscript but the abbreviated history presented serves to show that an interest in, and legislative action supporting early pay for performance concepts can clearly be observed as far back as hipaa’s passage in 1996.5 legislative push away from fee for service (ffs) and toward fee for value (i.e. value over volume) has continued since then. for example, multiple medical specialists including urologists, gastroenterologists and orthopedists have begun chronicling the movement and emphasis of value over volume.6-9 more specifically, the merit based incentive payment system (mips) is also being discussed by specialist communities.10 cost, specifically rising healthcare cost, has been central to this discussion since the origins of reimbursed care provision.11 while it is a core issue, cost represents merely half of the discussion as it relates to value.12 this is because mathematically, value is equal to the difference in two interventions in terms of outcome divided by cost.6 while mathematically, the value discussion seems straight forward, it is actually very complex and includes many other factors such as patient selection, outcomes, risk stratification, patient registry, guideline based practice, care coordination and others. use of clinical guidelines and registries and other best practices offer insight on practice decisions and may serve to reduce variability.6 as mentioned previously, the sum of all of this can be quantitatively described in terms of value, cost and quality or outcome. in medicine however, other variables are also measured and evaluated. these can include length of stay, readmission and complication rates.6 considerations for potential next steps for o&p the history of the development of the healthcare common procedure coding system (hcpcs) level ii device l codes used by o&p to describe devices and services provided are documented elsewhere.13 briefly, aopa and blue cross and blue shield from south carolina developed the template for the hcpcs l code system in the 1970’s. it was piloted in 1979 and soon after, other insurance companies began following use of the system.13 the development of the associated fee schedule reimbursement methodology can be found in the u.s. omnibus reconciliation act of 1987, which was implemented in 1989. the associated values were based on average payment amounts measured from 1986 to 1987 and are updated annually. regulations for this methodology are in the u.s. code of federal regulations (42 cfr 414.200). these coding and reimbursement methodologies have been associated with controversy by third party groups to government agencies who provide reimbursement based upon them and within the profession itself. it is important to note that in contrast to the cpt system, the l code system has not been maintained and updated with the same degree of modernization and applicability to current clinical o&p practice. for instance, the offices of the inspector generals for the u.s. department of health and human services and for the u.s. department of veterans affairs have published numerous reports related to o&p. some have been more clinically focused, exploring issues of population description, quality of care and other non-fiscal or less fiscally focused matters.14,15 however, the majority of these https://doi.org/10.33137/cpoj.v4i2.36125 3 highsmith mj, fantini cm, smith dg. contemplating health economics, coding and reimbursement in orthotics, prosthetics and pedorthics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.5. https://doi.org/10.33137/cpoj.v4i2.36125 issn: 2561-987x contemplating health economics, coding and reimbursement highsmith et al., 2021 cpoj special s p e c ia l i s s u e have been related to questionable or fraudulent procurement, acquisition, payment and purchasing,16-21 coding22 or billing23 related to o&p. additionally, editorial publications from members of the o&p community have also speculated as to whether or not the current and continued use of hcpcs l codes is a viable path forward.13,24,25 among the issues cited in these publications are: delays and uncertainty in the coding application process and the seemingly diminishing success rate of receiving newly developed codes for newly developed technology. the latter issue is further being discussed as a potentially limiting factor in the investment and pursuit of research and development efforts to explore creation of new technologies. the darpa/luke arm technology26-28 was cited in 2008 as an example of a government funded technological advancement that may not be assigned a code25 and as of this writing in 2021, the component remains uncoded. additional challenges with the current l code system include incorporation of professional service fees into the device reimbursement. this limits recognition of the contributions of the credentialed o&p clinician as a professional member of the healthcare team and perpetuates the image that the o&p clinician may serve more as device provider. restated, because the l-codes describing o&p interventions are included within durable medical equipment (i.e. fee for device), the prosthetist-orthotist may not necessarily be afforded or regarded with comparable professional standing relative to providers who describe their services using cpt codes (i.e. fee for service providers). to the authors’ knowledge, the o&p profession has not published data on the practitioner’s work and service as assessed by time, mental effort, judgment, technical skill, physical effort, amortized educational costs (both entry level and continuing education), psychological stress and other factors as other professions have. other issues cited include an inordinately lengthy list of codes relative perhaps to other professions. some o&p professionals have suggested there may be interest to reduce the number of codes while others have suggested that more codes, allowing greater descriptive specificity are needed. the debate over the number of codes is further complicated when considering assertions of misapplication of codes potentially due to misunderstanding. this is an issue echoed in a recent oig report.22 there are numerous other points of debate with the current coding system for o&p. to be clear, not all of the o&p community agrees that the l-code system is dysfunctional or in need of replacement. some have indicated it is adequate, some have indicated revision may be in order and still others may be interested in an alternative system all-together.13,24,25 call to action this manuscript provided a brief overview of the l-code system’s origins, controversies, strengths and weaknesses. however, the purpose was to challenge the profession to begin to contemplate next steps of coding and reimbursement against a backdrop where all of healthcare and medicine and reimbursement is clearly moving from fee for service to fee for value while o&p is currently in a different place entirely using a fee for device model. it would seem change is imminent but maybe not. it would seem timely for o&p to academically evaluate the strengths, weaknesses, opportunities, threats, merits and other considerations of: • staying with the current coding and reimbursement system, • revising and updating the current system, • alternate systems such as: o fee for service o fee for value o a hybrid system further, perhaps there would also be value in studying the history and methods used to formulate the coding and reimbursement systems of other providers and specialists as well as those of other nations.29-38 this could assist in determining if elements of other models could benefit o&p or if other methods and models would serve the profession better in their entirety. moreover, such an exercise could potentially be what is needed to affirm the current system is the best system and should remain in place. if however the o&p profession were to embark on the aforementioned discussion and conclude that the current system is not meeting the profession’s needs, perhaps completely reimagining the current hcpcs l coding and reimbursement methodology may be in order. to do this, it may be useful to objectively study and quantify the value of o&p professional service using methodologies outlined and previously used by other professions. moving toward a novel, rvu based coding and reimbursement model used by and known to work for other healthcare service providers who also work with devices, could improve the professional standing of the o&p clinician within the interdisciplinary healthcare team and personify o&p professionals as service providers. in summary, the prior ssc1 was comprehensive and provided important professional awareness of and a call to action to engage more in economic science related to the o&p body of knowledge. the current call to action is in the context of legislative action driving all areas of healthcare toward value over volume. this is essentially driven by aligning incentives in such a way to prioritize the patient’s interests, in terms of their outcomes above all other considerations. in this, it seems wise for professions to lead and be an active part of change or risk having legislators https://doi.org/10.33137/cpoj.v4i2.36125 4 highsmith mj, fantini cm, smith dg. contemplating health economics, coding and reimbursement in orthotics, prosthetics and pedorthics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.5. https://doi.org/10.33137/cpoj.v4i2.36125 issn: 2561-987x contemplating health economics, coding and reimbursement highsmith et al., 2021 cpoj special s p e c ia l i s s u e and payers make decisions on behalf of involved professions. acknowledgements none. declaration of conflicting interests the opinions and assertions expressed herein are those of the authors and do not necessarily reflect the official policy or position of any government or healthcare agency or academic institution to include the uniformed services university, the department of defense and/or the department of veterans affairs. dr. douglas smith received salary support through the uniformed services university of the health sciences under award number hu00011920105 to the henry m. jackson foundation for the advancement of military medicine, inc., and has been prepared in collaboration with the center for rehabilitation sciences research, department of physical medicine & rehabilitation, uniformed services university and the department of rehabilitation, walter reed national military medical center. sources of support none. references 1.stevens pm, highsmith mj. an introduction to the proceedings of the aaop’s state-of-the-science conference on the economic science of lower-limb prosthetic rehabilitation. j prosthet orthot. 2019;31(1s):1-2. doi: 10.1097/jpo.0000000000000233 2.dobson a, el-gamil a, shimer m, davanzo je. economic value of prosthetic services among medicare beneficiaries: a claimsbased retrospective cohort study. j prosthet orthot. 2019; 31(1s):94-100. doi: 10.7205/milmed-d-15-00545 3.highsmith mj, kahle jt, bongiorni dr, sutton bs, groer s, kaufman kr. safety, energy efficiency, and cost efficacy of the c-leg for transfemoral amputees: a review of the literature. prosthet orthot int. 2010; 34(4):362-377. doi: 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[internet]. the o&p edge. 2008, [cited 2021, january 5], available from: https://opedge.com/articles/viewarticle/2008-08-01/200808_01 14.daigh jd. healthcare inspection, foot care for patients with diabetes and additional risk factors for amputation [internet]. u.s. department of veterans affairs, office of inspector general. report #11-00711-74. 2013, [cited 2021, january 5], available from: https://www.va.gov/oig/pubs/vaoig-11-00711-74.pdf 15.daigh jd. healthcare inspection. prosthetic limb care in va facilities [internet]. u.s. department of veterans affairs, office of inspector general. report #11-02138-116. 2012, [cited 2021, january 5], available from: https://www.va.gov/oig/pubs/vaoig11-02138-116.pdf 16.jarmon gl. medicare improperly paid suppliers for durable medical equipment, prosthetics, orthotics, and supplies provided to beneficiaries during inpatient stays [internet]. u.s. department of health and human services. office of the inspector general. a09-17-03035. 2018, [cited 2021, january 5], available from: https://oig.hhs.gov/oas/reports/region9/91703035.pdf 17.levinson dr. cms has not promulgated regulations to establish payment requirements for prosthetics and customfabricated orthotics [internet]. u.s. department of health and human services. office of the inspector general. oei-07-1000410. 2012, [cited 2021, january 5], available from: https://oig.hhs.gov/oei/reports/oei-07-10-00410.pdf 18.finn bj. audit of the management and acquisition of prosthetic limbs. u.s. department of veterans affairs [internet]. office of inspector general. report #11-02254-102. 2012, [cited 2021, january 5], available from: https://www.va.gov/oig/pubs/vaoig11-02254-102.pdf 19.brown jg. medicare losses resulting from early payments for durable medical equipment, prosthetics, orthotics and supplies [internet]. u.s. department of health and human services. office of the inspector general. oei-03-99-00620. 2000, [cited 2021, january 5], available from: https://oig.hhs.gov/oei/reports/oei-0399-00620.pdf 20.brown jg. medicare payments for orthotics. inappropriate payments [internet]. u.s. department of health and human services. office of the inspector general. oei-02-99-00120. 2000, [cited 2021, january 5], available from: https://oig.hhs.gov/oei/reports/oei-02-99-00120.pdf https://doi.org/10.33137/cpoj.v4i2.36125 https://opedge.com/articles/viewarticle/2008-08-01/2008-08_01 https://opedge.com/articles/viewarticle/2008-08-01/2008-08_01 https://www.va.gov/oig/pubs/vaoig-11-00711-74.pdf https://www.va.gov/oig/pubs/vaoig-11-02138-116.pdf https://www.va.gov/oig/pubs/vaoig-11-02138-116.pdf https://oig.hhs.gov/oas/reports/region9/91703035.pdf https://oig.hhs.gov/oei/reports/oei-07-10-00410.pdf https://www.va.gov/oig/pubs/vaoig-11-02254-102.pdf https://www.va.gov/oig/pubs/vaoig-11-02254-102.pdf https://oig.hhs.gov/oei/reports/oei-03-99-00620.pdf https://oig.hhs.gov/oei/reports/oei-03-99-00620.pdf https://oig.hhs.gov/oei/reports/oei-02-99-00120.pdf 5 highsmith mj, fantini cm, smith dg. contemplating health economics, coding and reimbursement in orthotics, prosthetics and pedorthics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.5. https://doi.org/10.33137/cpoj.v4i2.36125 issn: 2561-987x contemplating health economics, coding and reimbursement highsmith et al., 2021 cpoj special s p e c ia l i s s u e 21.wright s. use of surety bonds to recover overpayments made to dmepos suppliers [internet]. u.s. department of health and human services. office of the inspector general. oei-03-1100351. 1997, [cited 2021, january 5], available from: https://oig.hhs.gov/oei/reports/oei-03-11-00351.pdf 22.reinkemeyer lm. use of not otherwise classified codes for prosthetic limb components [internet]. u.s. department of veterans affairs. office of inspector general. report #16-01913223. 2018, [cited 2021, january 5], available from: https://www.va.gov/oig/pubs/vaoig-16-01913-223.pdf 23.levinson dr. questionable billing by suppliers of lower limb prostheses [internet]. u.s. dept. of health and human services. office of the inspector general. oei-02-10-00170. 2011, [cited 2021, january 5], available from: https://oig.hhs.gov/oei/reports/oei-02-10-00170.pdf 24.stark g, stiner b. l-code obstacles: experience from the front lines [internet]. the o&p edge. 2008. [cited 2021, january 5], available from: https://opedge.com/articles/viewarticle/2008-0801/2008-08_03 25.phillips otto j. l-codes: what's wrong? what's right? [internet]. the o&p edge. 2008. [cited 2021, january 5], available from: https://opedge.com/articles/viewarticle/2008-08-01/2008-08_02 26.resnik l, latlief g, klinger sl, sasson n, walters ls. do users want to receive a deka arm and why? overall findings from the veterans affairs study to optimize the deka arm. prosthet orthot int. 2014; 38(6):456-466. doi: 10.1177/0309364613506914 27.resnik l, klinger sl, etter k. the deka arm: its features, functionality, and evolution during the veterans affairs study to optimize the deka arm. prosthet orthot int. 2014; 38(6):492-504. doi: 10.1177/0309364613506913 28.resnik l. research update: va study to optimize deka arm. j rehabil res dev. 2010; 47(3):ix-x. doi:10.1682/jrrd.2010. 03.0034, 29.hsiao wc, braun p, becker er, dunn dl, kelly n, causino n, et al. results and impacts of the resource-based relative value scale. med care. 1992;30(11 suppl):ns61-79. doi: 10.1097/00005650-199211001-00006 30.hsiao wc, braun p, dunn dl, becker er, yntema d, verrilli dk, et al. an overview of the development and refinement of the resource-based relative value scale. the foundation for reform of u.s. physician payment. med care. 1992; 30(11 suppl):ns1-12. doi: 10.1097/00005650-199211001-00001 31.becker er, dunn d, braun p, hsiao wc. refinement and expansion of the harvard resource-based relative value scale: the second phase. am j public health. 1990; 80(7):799-803. doi: 10.2105/ajph.80.7.799 32.hsiao wc, becker er. paying physicians according to their resource-costs: the development of a resource-based relative value scale. health policy. 1989; 12(3):257-261. doi: 10.1016/01688510(89)90075-4 33.hsiao wc, braun p, kelly nl, becker er. results, potential effects, and implementation issues of the resource-based relative value scale. jama. 1988; 260(16):2429-2438. doi:10.1001/jama. 1988.03410160105013 34.hsiao wc, braun p, dunn d, becker er. resource-based relative values. an overview. jama. 1988; 260(16):2347-2353. doi:10.1001/jama.1988.03410160021004 35.hsiao wc, braun p, yntema d, becker er. estimating physicians' work for a resource-based relative-value scale. n engl j med. 1988; 319(13):835-841. doi: 10.1056/ nejm198809293191305 36.hsiao wc, braun p, dunn d, becker er, denicola m, ketcham tr. results and policy implications of the resource-based relativevalue study. n engl j med. 1988; 319(13):881-888. doi: 10.1056/nejm198809293191330 37.hsiao wc. the resource-based relative value scale: an option for physician payment. inquiry. 1987;24(4):360-361. 38.cutti ag, lettieri e, verni g. health technology assessment as theoretical framework to assess lower-limb prosthetics—issues and opportunities from an international perspective. j prosthet orthot. 2019; 31(1s):55-73. doi: 10.1097/jpo.0000000000000235 authors scientific biography m. jason highsmith, pt, dpt, phd, cp, faaop, attended northwestern university’s prosthetics program in 2004 and was certified following residency in 2006. he is dual licensed in physical therapy and prosthetics. he currently serves as the va’s national director of orthotic, prosthetic & pedorthic clinical services program office. he is joint appointed as a professor at the university of south florida (usf), is a past-president of the american academy of orthotists & prosthetists and is a captain (physical therapist) in the us army reserves. dr. highsmith manages a considerable research portfolio and has published numerous peer-reviewed scientific manuscripts. the views expressed in this article are his alone, and do not represent the us departments of defense, veterans affairs, any university or any other organization. christopher fantini, mspt, cp, boco, is a board-certified prosthetist/orthotist with over 25 years of physical rehabilitation experience. mr. fantini received a master of science in physical therapy from columbia university in new york city and earned post graduate certification in prosthetics from northwestern university in chicago. mr. fantini has participated in notable work on advanced prosthetic devices to help facilitate the progression of emerging concepts & technologies to their clinical application. he has authored numerous peer reviewed articles as well as several chapters in texts relating to prosthetic care. he participates in the education/mentoring of residents in the disciplines of physical medicine & rehabilitation and orthotics/prosthetics. he has and continues to work on several projects relating to both direct patient care as well as strategic planning to advance the field of o&p. the views expressed in this article are his alone, and do not represent the us department of veterans affairs or any other organization. https://doi.org/10.33137/cpoj.v4i2.36125 https://oig.hhs.gov/oei/reports/oei-03-11-00351.pdf https://www.va.gov/oig/pubs/vaoig-16-01913-223.pdf https://oig.hhs.gov/oei/reports/oei-02-10-00170.pdf https://opedge.com/articles/viewarticle/2008-08-01/2008-08_03 https://opedge.com/articles/viewarticle/2008-08-01/2008-08_03 https://opedge.com/articles/viewarticle/2008-08-01/2008-08_02 6 highsmith mj, fantini cm, smith dg. contemplating health economics, coding and reimbursement in orthotics, prosthetics and pedorthics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.5. https://doi.org/10.33137/cpoj.v4i2.36125 issn: 2561-987x contemplating health economics, coding and reimbursement highsmith et al., 2021 cpoj special s p e c ia l i s s u e douglas g. smith, md is a board-certified orthopaedic surgeon with over 30 years of experience in amputation surgery, the rehabilitation of individuals with limb loss, prosthetic prescription and prosthetic evaluation. he is professor emeritus in the department of orthopaedics and sports medicine at the university of washington in seattle. he is also a professor in the department of physical medicine and rehabilitation at the uniform services university of the health sciences in bethesda, maryland. he works for the henry m. jackson foundation for the advancement of military medicine, and in his role as the chief orthopaedic advisor for the center for rehabilitation sciences research in the department of physical medicine and rehabilitation at the uniform services university he provides clinical education, consultation to the multi-disciplinary amputee care team and he supervises clinical research in limb salvage, amputation surgery and rehabilitation. he also serves on the american orthotic and prosthetic association (aopa) medical advisory board. the views expressed in this article are his alone, and do not represent the us department of defense, any university or any other organization. https://doi.org/10.33137/cpoj.v4i2.36125 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 research article yazgan a, kutlutürk s, lechler k. clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.8. https://doi.org/10.33137/cpoj.v4i1.35297 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.35297 1 yazgan a, kutlutürk s, lechler k. clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.8. https://doi.org/10.33137/cpoj.v4i1.35297 research article clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey yazgan a1,2*, kutlutürk s3, lechler k4 1 orthotics prosthetics master of science program, graduate school of healthy sciences, istanbul medipol university, istanbul, turkey. 2 össur turkey academy, istanbul, turkey. 3 department of physical therapy and rehabilitation, school of healthy sciences, istanbul medipol university, istanbul, turkey. 4 össur medical office, r&d össur ehf, reykjavik, iceland. introduction lower extremity amputation causes impairment in functional mobility, sensation, body image and quality of life. as the functional mobility decreases, quality of life (qol) decreases and the risk for joint degradation increases.1,2 typical challenges encountered in rehabilitation of individuals with transfemoral amputation (itf) are reduced walking distances,3 balance impairment4 and increased metabolic cost.5 adequate prosthetic component selection for itf is a critical factor to assist in prevention of additional burden and the restoration of functional mobility.6 a large variety of prosthetic knee designs are available for individuals with transfemoral amputation.7 the appropriate prescription requires comprehensive consideration to provide safety, satisfaction and function,8 and therefore relies on qualified professionals to select the adequate solution. in line with theses objectives, the development of prosthetic knees aims to create a device that provides balance confidence, balance ability and to support walking performance in itf.9 historically, transfemoral prostheses use a passive, mechanical mechanism to control the swing and stance phases of the prosthetic gait. today, microprocessor controlled knees (mpk) are becoming more common.10 even though nonmpk and mpk are functionally similar in range of motion open access volume 4, issue 1, article no.8. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: clinical outcome assessments provide important input for the rehabilitation of individuals with transfemoral amputation. differences in prosthetic knee designs may influence clinical outcomes. objective(s): the aim of this study was to compare functional mobility, balance, prosthetic satisfaction and quality of life in individuals with unilateral transfemoral amputation with microprocessorcontrolled (mpk) and non-microprocessor knee designs (non-mpk). methodology: the study included ten experienced mpk (rheo knee) users (group 1) and ten experienced non-mpk (total knee® 2000) users (group 2). for mobility; the 6 minute walk test (6mwt), for balance; the berg balance scale (bbs), single leg stand test (slst) and four square step test (fsst), for quality of life; the nottingham health profile (nhp) and for prosthetic satisfaction; the satisfaction with prosthesis questionnaire (satpro) were administered. findings: 6mwt results of the mpk group were significantly higher than non-mpk group (p <0.05). in the mpk group a strong negative correlation was found between the fsst and the 6mwt (r= -0.661, p=0.038). no statistically significant differences were found between the groups (p>0.05) comparing balance, prosthesis satisfaction and quality of life values. conclusion: the findings will inform about the patient’s prognosis and the expected clinical outcomes when prescribing an mpk or an non-mpk. individuals with unilateral transfemoral amputation covered longer distances using an mpk compared to non-mpk. article info received: december 22, 2020 accepted: june 22, 2021 published: june 29, 2021 citation yazgan a, kutlutürk s, lechler k. clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.8. https://doi.org/10.33137/cpoj.v4i 1.35297 keywords balance, functional mobility, prosthetic satisfaction, transfemoral amputation, quality of life, prosthesis * corresponding author ayse yazgan, össur turkey academy, istanbul, turkey; i̇stanbul medipol university orthotics prosthetics master of science program, istanbul, turkey. e-mail: ayazgan@ossur.com orcid id: https://orcid.org/0000-0003-0744-503x https://doi.org/10.33137/cpoj.v4i1.35297 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.35297 https://doi.org/10.33137/cpoj.v4i1.35297 mailto:ayazgan@ossur.com https://orcid.org/0000-0003-0744-503x 2 yazgan a, kutlutürk s, lechler k. clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.8. https://doi.org/10.33137/cpoj.v4i1.35297 issn: 2561-987x clinical outcomes comparing two prosthetic knee designs yazgan et al. 2021 cpoj acting, within one degree of freedom, mpk designs allow dynamic management of the motion behavior throughout the gait cycle.8 the sensor technology allows for quicker adaptation to varying walking speeds by making decisions on the application of resistance and appropriate transitions.11 walking with an mpk has been reported to improve gait symmetry,12 assist in more physiological mobility and loading pattern on the prosthetic side,13 and reduce loading on the contralateral side.14 some clinical studies are inconclusive,14,15 others report clear differences between the mpk and non-mpk in functional performance, balance and psychology parameters.16 the majority of literature comparing functional outcomes have been conducted in western societies and rarely among turkish itf. differences in culture or rehabilitation practices may affect these outcomes. the aim of the study was to compare balance, functional mobility, prosthetic satisfaction and qol in individuals with unilateral transfemoral amputation using non-mpk versus mpk after long term adaptation in turkey. we hypothesized that there is a difference between individuals using mkp and non-mpk in balance, functional mobility, prosthetic satisfaction and quality of life. methodology a two group design was chosen to compare objective performances, observer-reported and patient-reported outcomes after longterm adaptation on the prescribed mpk; (group 1) rheo knee (össur, reykjavik, iceland) and (group 2) non-mpk; total knee® 2000 (össur, reykjavik, iceland). for consistency and to reduce confounding factors all participants were recruited from one clinic. all twenty subjects used the energy storing and-return (esar) variflex (össur, reykjavik, iceland) foot design. the study was approved by istanbul medipol university ethics institutional review board, and informed written consent was obtained. the criteria for enrollment included unilateral transfemoral amputation, age between 18-59 years and a minimum of one year experience with the same prosthesis, medicare functional classification level k3 or k4,17 and the ability to walk at least 10 m without using any assistive device. criteria for exclusion were chronic residual limb skin breakdown. subjects were also excluded if they had an acute illness, chronic illness, dependency on walking aids, neuromuscular problems or any secondary medical condition that preclude performance of the test protocol. the subject profile data is presented in table 1. balance was evaluated using the bbs,18 fsst19 and slst.20 the measures were administered in the same order for all the subjects starting with the bbs. the 14 items of the bbs were answered by the participants with the supervision of researchers only assisting when the participant asked for clarification. following this the observational section of the bbs test with its 5 point ordinal scale (0-4) was administered. the maximum score that can be achieved is 56, with higher scores reflecting better balance. a score of 45 is required for independent safe ambulation.18 following the bbs, static balance was assessed by the slst. with a 5 minute break between each task single leg standing was timed on the amputated and non-amputated side. participants started on the nonamputated side inside a parallel bar. the time the participants stood on one leg was measured with a stopwatch and recorded in "seconds". the stopwatch was started as the participants raised the contralateral leg and removed the hands or any support from the side bars. time was stopped when the participants reached out for support or contacted the ground with the contralateral side or by reaching the maximum standing time of 30 seconds.20 for the fsst individuals were asked to step across four squares, as quickly as possible following the instructions provided by gouelle et. al. 2020.19 participants had to step forward, backward, right, and left and the time of completion was noted. the fsst was repeated two times and the second result was reported. the 6mwt was administered according to the instructions of the american thoracic society21 in order to capture the walking distance covered by the participants within the 6 minutes given. the 30 meters walkway was solid and leveled and marked every 3 meters. pylons marked the end points. participants were instructed to start walking when ready and follow the researcher's instructions and reminded not to run or jog. as soon as the participants started to walk the timer was started. with the sound of the timer the subject stopped walking and sat down on a chair. the distance covered within 6 minutes was recorded. the nottingham health profile (nhp) and the satisfaction with prosthesis questionnaire (satpro) were administered in a paper based format in turkish.22,23 all measures were conducted within half a day and paperbased results were scanned and transferred to a digital format. statistical analysis using an effect size of 1.629 based on previously reported data for bbs, 6mwt, nhp and satpro,23 a sample size of 18 (9 per group) was deemed necessary to ensure a type1 error rate of 0.05 and power of 0.95. to account for drop outs, the study was conducted with the participation of 20 transfemoral individuals with amputation. all analyses were performed using spss version 21.00 (ibm, usa). the p value was set to 0.05 in all statistics. the mann whitney u test was used to detect group differences. the relationship https://doi.org/10.33137/cpoj.v4i1.35297 https://www.ossur.com/en-ca/prosthetics/knees/rheo-knee https://www.ossur.com/en-ca/prosthetics/knees/total-knee-2000 https://www.ossur.com/en-ca/prosthetics/feet/vari-flex https://www.ossur.com/en-ca/prosthetics/feet/vari-flex 3 yazgan a, kutlutürk s, lechler k. clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.8. https://doi.org/10.33137/cpoj.v4i1.35297 issn: 2561-987x clinical outcomes comparing two prosthetic knee designs yazgan et al. 2021 cpoj between fsst and 6mwt was evaluated using pearson correlation. results twenty itf were recruited at a single study site. no differences in age, height, weight, body mass index, time since amputation, prosthetic experience, experience with mpk/non-mpk, patient-reported daily standing and daily exercise time between groups (p> 0.05) could be identified (table 1, table 2). there were no differences between two groups for the bbs, slst and fsst (p> 0.05) (table 3). all participants achieved the maximum of 30 seconds for the slst on the sound side. there were no differences between the two groups for the satpro and nhp scores (p> 0.05) (table 4). nhp subparameters range from 0 to 100. higher nhp scores relate to more pain, more social isolation, more emotional reaction but less physical abilities, energy level and sleep. table 1: participant details group 1 (mpk) (n=10) group 2 (non-mpk) (n=10) mann whitney u test min-max mean±sd min-max mean±sd u z p age 23.0-50.0 38.0±8.4 18.0-59.0 39.3±13.0 49.00 -0.07 0.97 bmi (kg/m2) 19.0-26.9 23.7±2.6 16.9-29.7 24.3±4.1 46.00 -0.30 0.79 height (cm) 170.0-183.0 177.6±4.4 150.0-191.0 170.1±13.2 32.00 -1.36 0.19 weight (kg) 55.0-90.0 75.0±10.6 46.0-88.0 70.1±13.7 39.50 -0.79 0.43 time of amputation (years) 3.0-37.0 22.5±11.1 1.5-31.0 14.1±12.7 31.00 -1.43 0.16 prosthetics use experience (years) 2.0-35.0 18.9±9.7 1.0-31.0 13.1±12.3 34.50 -1.17 0.24 experience with non-mpk/mpk (years) 1.0-8.0 5.7±2.9 1.0-10.0 3.7±3.2 31.00 -1.46 0.16 daily standing time (hour) 1.0-16.0 8.8±4.7 2.0-15.0 7.4±5.0 40.50 -0.72 0.48 daily exercise time (hour) 1.0-4.0 2.1±1.4 1.0-4.0 2.1±1.2 43.00 -0.55 0.63 min: minimum, max: maximum, sd: standard deviation, p value is significant when p< 0.05. table 2: participant gender, side of amputation, cause of amputation and residual limb length. group 1 (mpk) group 2 (non-mpk) gender female 1 (10%) 3 (30%) male 9 (90%) 7 (70%) amputation side right 5 (50%) 7 (70%) left 5 (50%) 3 (30%) cause of amputation trauma 8 (80%) 4 (40%) congenital abnormalities 1 (10%) 3 (30%) peripheral vascular disorder 1 (10%) 1 (10%) cancer 0 (0%) 1 (10%) infections 0 (0%) 1 (10%) residual limb length* short 1 (10%) 2 (20%) medium 7 (70%) 4 (40%) long 2 (20%) 4 (40%) *as defined in the standard iso/wd 8548-2:2018(e): amputation level= short (proximal third)/medium (middle third)/long (distal third) table 3: comparison of the balance parameters of two groups. group 1 (mpk) group 2 (non-mpk) mann whitney u test min-max mean±sd min-max mean±sd u p z slst(sec) 0.0-5.0 1.7±2.0 0.0-7.0 0.8±2.2 35.00 0.28 -1.33 fsst(sec) 2.6-6.3 4.9±1.2 4.0-7.8 5.4±1.3 44.00 0.68 -0.45 bbs 50.0-54.0 52.5±1.7 46.0-55.0 51.4±2.8 -1.01 0.35 37.00 slst: single leg stand test prosthetic side, fsst: four step square test, bbs: berg balance scale, min: minimum, max: maximum, sec.: second, sd: standard deviation, p value is nnn n n significant when p<0.05. https://doi.org/10.33137/cpoj.v4i1.35297 4 yazgan a, kutlutürk s, lechler k. clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.8. https://doi.org/10.33137/cpoj.v4i1.35297 issn: 2561-987x clinical outcomes comparing two prosthetic knee designs yazgan et al. 2021 cpoj a statistically significant difference was found between two groups for the 6mwt distance (p< 0.05). 6mwt results of group 1 were statistically significantly higher than group 2 (p< 0.05) (table 5). for group 1, a high negative correlation was found between the fsst and 6mwt (p< 0.05) (table 6). discussion our study compared two groups of itf (mpk and non-mpk) who had been using their prosthesis between 1 and 10 years. the results indicate that subjects in the mpk group walked further compared to subjects using a non-mpk. no difference between the groups was found for patient reported balance, prosthesis satisfaction and qol. in addition, a high correlation was found between the dynamic balance and functional activity of itf using mpk. the parallel group design allowed us to avoid order affects that have been reported in previous studies.24,25 in addition, previous studies using a randomized cross over design have had shorter adaptation and as a result failed to demonstrate that subjects reached a plateau in their performance measures.17 by contrast a minimum usage time of one year makes it highly likely that performance plateau was reached for the subjects in this study. balance is beneficial for daily functioning of patients with a lower limb amputation and often assessed by the slst20 to reliably test the balance performance. it is known that slst is less on the amputated side than on the unaffected side. comparing the two groups by slst, no statistically significant difference between the non-mpk and the mpk could be detected on the prosthetic side. table 4: comparison of quality of life (nhp) and patient satisfaction (satpro). group 1 (mkp) group 2 (non-mpk) mann whitney u test mean±sd mean ±sd u z p patient satisfaction (satpro) 33.3±5.2 35.7±2.7 39.50 -0.80 0.43 quality of life (nhp subtests) pain 6.5±7.8 11.7±15.8 41.50 -0.67 0.52 social isolation 0.0±0.0 3.5±11.2 45.00 -1.00 0.73 emotional reaction 1.0±3.3 1.8±5.5 49.50 -0.07 0.97 physical abilities 4.4±7.7 9.7±11.9 39.00 -0.94 0.43 energy level 11.0±17.8 11.0±17.8 50.00 0.00 1.00 sleep 1.3±4.0 0.0±0.0 45.00 -1.00 0.73 total score 24.2±27.8 37.8±36.0 44.50 -0.88 0.39 min: minimum, max: maximum, sd: standard deviation, p value is significant when p< 0.05. table 5: comparison of 6mwt distance of two groups. group 1 mkp group 1 non-mpk mann whitney u test mean±sd min-max mean±sd min-max u z p 6 mwt (m) 474.8±56.1 386.0-552.0 346.6±60.5 276.0-445.0 7.00 -3.25 0.00* 6mwt: 6 minute walk test, sd: standard deviation m: meter, p value is significant when p< 0.05. table 6: correlation between 6mwt, fsst, bbs, slst and residual limb length within the two groups. group 1 (mkp) group 2 (non-mpk) 6mwt (m) 6mwt (m) r* p* r* p* bbs 0.20 0.66 0.39 0.71 slst (sec) 0.37 0.37 0.54 0.06 fsst (sec) -0.66* 0.02* -0.40 0.22 residual limb length (short/medium/long)** 0.17 0.62 0.42 0.22 6mwt: 6 minute walk test, bbs: berg balance scale, fsst: four square step test, slst: single leg stand test, m: meter, sec: second, * spearman correlation test, statistical significance limit is 0.05, r: spearman’s rank correlation coefficient. **according to iso/wd 8548-2:2018(e): amputation level= short (proximal third)/medium (middle third)/long (distal third). https://doi.org/10.33137/cpoj.v4i1.35297 5 yazgan a, kutlutürk s, lechler k. clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.8. https://doi.org/10.33137/cpoj.v4i1.35297 issn: 2561-987x clinical outcomes comparing two prosthetic knee designs yazgan et al. 2021 cpoj major et. al.18 reported a bbs median score of 52 (49-54) for itf and showed high reliability and validity of bbs in community-dwelling persons with lower extremity amputation. despite not being specific to prosthetic knees, differences in bbs score of 49.0± 9.9 were found26 between mechanical and hydraulic (non-mpk) stance controlled knees. also, bbs showed sensitivity when transitioning from the non-mpk to mpk (rheo knee) with an increase for mpk users scoring between 54 and 56.15 both studies reported on bbs shortly after transitioning. in our study, no statistically significant difference in bbs scores was found after a long adaptation period. the bbs scores (52.50 ± 1.26) being generally high may indicate that users have adapted well and the bbs scores were not sensitive to differences in knee component designs for individuals having used them for a long time. lythgo et. al.,27 examined the function, gait and dynamic balance of itf using two different non-mpk designs. there was no difference in fsst (13.6±3.0 / 13.2±2.2 seconds) for the two non-mpk. our findings showed 4.85 seconds in fsst for mkp and 5.44 seconds for non-mpk. unlike the literature19,27,28 both groups in our study performed almost 1sec faster than kahle et. al. 201629 indicating a generally higher dynamic balance level. kahle et. al. compared two socket technologies and their volume adaptation on one single user. our cohort included high active users, e.g. playing soccer, dancing, etc. which likely explains their improved performances. the small difference in favor of the non-mpk may be explained by the higher ratio of congenital amputation cause and longer residual limb length in the non-mpk group. kamali et. al.30 indicated that a longer residual limb may improve standing stability and dynamic balance. hafner et. al.8 showed that the transition from non-mpk to mpk significantly increases function and performance. in our study there was a significant difference between the two groups in walking distance covered during the 6mwt. in contrast to the aforementioned studies that showed performance difference after only a couple of weeks adaptation time, our study included two different groups and showed these effects after a long adaptation period of several years. using the nhp, demet et. al. assessed the importance of different factors associated with health related qol in llas.31 they found physical disability, pain and energy level32 to be the most important factors and mobility to be the only independent factor for health related qol measured by nhp. ülger et. al.26 found a total nhp score of 91.1±28.6 and 51.9±12.5 for two different non-mpk in contrast to higher scores in our study for both non-mpk and mpk of 37.77±35.97 and 24.21±27.82, respectively. burçak et. al.33 reported on increased quality of life, improved functional performance, increased prothesis satisfaction and decreased perception of body image disturbance when using an mpk prosthesis versus a non-mpk. they used the satpro questionnaire for prosthetic satisfaction and observed an increase in the use of mkp. we found no difference in qol and prosthesis satisfaction between the two groups. azuma et. al.34 found a correlation between dynamic balance and walking ability in itf using the bbs and 6mwt. similarly, our study supports the relationship between balance parameters and functional activity. comparing both groups the mpk showed a high negative correlation between 6mwt and fsst. itf using an mpk demonstrated good dynamic balance and increased functional activity. limitations the limitations in this study include the recruitment constraints, resulting in a small sample size and therefore the results cannot be generalized. although small samples limit generalizability of the results, small samples are common in rehabilitation research35 and they relate to identification, recruitment, and enrollment of subjects. the two group design is lacking the statistical strength of a paired design. in our study, balance, functional mobility, prosthesis satisfaction and qol of itf using mpk and nonmpk were compared in two similarly profiled groups with long-term accommodation to their prescribed prosthesis. a cross over design with such a long adaptation time would be unfeasible. in future studies we would like to include more subjects to show differences in balance and mobility with mkp and non-mpk after long-term adaptation. we propose that in future studies, more itf using different types of prosthetic knee design should be included to provide more information for practitioners. outcomes were only measured at one time point, and thus might only reflect the specific situation at the time of measurement. longitudinal designs allow statement on reliability not possible herein. no objective balance measures were used to add strength and sensitivity to the findings for the patient and observer-reported measures. the inclusion of only one type of mpk (rheo knee) and non-mpk (total knee® 2000) does not allow to generalize these results to other prosthetic knee designs. however limiting the number of knee designs allowed for the identification of the specific outcomes related to the designs. conclusion while this study did not highlight differences in most of the clinical outcomes administered, subjects using an mpk were able to walk longer distances in comparison to those using a non-mpk. these findings will provide decision makers with a more accurate prognosis when selecting between the two knee designs. https://doi.org/10.33137/cpoj.v4i1.35297 6 yazgan a, kutlutürk s, lechler k. clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.8. https://doi.org/10.33137/cpoj.v4i1.35297 issn: 2561-987x clinical outcomes comparing two prosthetic knee designs yazgan et al. 2021 cpoj acknowledgements we thank össur research and development department for providing technical advice and support. thanks to micah nicholls, scientific director at össur for proofreading context and the english. declaration of conflicting interests the authors had no interests which might be perceived as posing a conflict or bias. author contribution • ayse yazgan: contributed to the study concept and design, participated in data gathering, analyzed and interpreted data, contributed to the drafting of the manuscript, read and approved the final manuscript. • seval kutlutürk: contributed to the study concept and design, analyzed and interpreted data, contributed to the drafting of the manuscript, read and approved the final manuscript. • knut lechler: analyzed and interpreted data, contributed to the drafting of the manuscript, read and approved the final manuscript. sources of support össur medical office, r&d össur ehf, reykjavik, iceland. ethical approval the study was approved by istanbul medipol university ethics institutional review board, and informed written consent was obtained. references 1.breakey jw. body image: the lower-limb amputee. j prosthet orthot. 1997; 9(2): 58-66. doi:10.1097/00008526-19970092000005 2.struyf pa, van heugten cm, hitters mw, smeets rj. the prevalence of osteoarthritis of the intact hip and knee among traumatic leg amputees. arch phys med rehabil. 2009; 90(3): 440 446. doi:10.1016/j.apmr.2008.08.220 3.hofstad cj, bongers kt, didden m, van ee rf, keijsers nl. maximal walking distance in persons with a lower limb amputation. sensors. 2020; 20(23): 6770. doi:10.3390/ s20236770 4.geurts ac, mulder tw, nienhuis b, rijken ra. postural reorganization following lower limb amputation. possible motor and sensory determinants of recovery. scand j rehabil med. 1992; 24(2): 83-90. 5.esquenazi a, digiacomo r. rehabilitation after amputation. j am podiatr med assoc. 2001; 91(1): 13-22. doi:10.7547/8750731591-1-13 6.stevens pm, wurdeman sr. prosthetic knee selection for individuals with unilateral transfemoral amputation: a clinical practice guideline. j prosthet orthot. 2019; 31(1): 2-8. doi: 10.1097/jpo.0000000000000214 7.michael jw. modern prosthetic knee mechanisms. clin. orthop. relat. res. 1999; 361: 39-47. doi:10.1097/00003086-19990400000006 8.hafner bj, willingham ll, buell nc, allyn kj, smith dg. evaluation of function performance and preference as transfemoral amputees transition from mechanical to microprocessor control of the prosthetic knee. arch phys med rehabil. 2007; 88(2): 207-17. doi:10.1016/j.apmr.2006.10.030 9.wong ck, rheinstein j, michelle a. stern. benefits for adults with transfemoral amputations and peripheral artery disease using microprocessor compared with nonmicroprocessor prosthetic knees. am j phys med rehabil. 2015; 94(10): 804-810. doi:10.1097/phm.0000000000000265 10.kadhim fm, chiad js, takhakh am. design and manufacturing knee joint for smart transfemoral prosthetic. iop conf ser mater. sci eng. 2018; 454. doi:10.1088/1757-899x/454/1/012078 11.palmer ml, charles r. bisbee iii. computer controlled prosthetic knee device. united states patent no. 7655050, 2010/feb/2. 12.kaufman kr, frittoli s, frigo ca. gait asymmetry of transfemoral amputees using mechanical and microprocessorcontrolled prosthetic knees. clin biomech. 2012; 27(5): 460-465. doi:10.1016/j.clinbiomech.2011.11.011 13.mileusnic mp, rettinger l, highsmith mj, hahn a. benefits of the genium microprocessor controlled prosthetic knee on ambulation, mobility, activities of daily living and quality of life: a systematic literature review. disabil rehabil assist technol. 2019; 1-12. doi:10.1080/17483107.2019.1648570 14.bellmann md, schmalz t, blumentritt s. comparative biomechanical analysis of current microprocessor-controlled prosthetic knee joints. arch phys med rehabil. 2010; 91(4): 644652. doi:10.1016/j.apmr.2009.12.014 15.howard cl, chris w, bonnie p, dobrivoje ss. comparison of mobility and user satisfaction between a microprocessor knee and a standard prosthetic knee: a summary of seven single-subject trials. int j rehabil res. 2018; 41(1): 63-73. doi:10.1097/mrr.0000000000000267 16.şen ei̇, aydın t, buğdaycı d, kesiktaş fm. effects of microprocessor-controlled prosthetic knees on self-reported mobility, quality of life, and psychological states in patients with transfemoral amputations. acta orthop traumatol turc. 2020; 54(5): 502. doi:10.5152/j.aott.2020.19269 17.hcfa common procedure coding system hcpcs 2001. washington (dc): us government printing office [internet]. 2001, [cited 2021, june 28], available from: https://archive.org/details/hcfacommonproced00unit/page/n9/mod e/2up 18.major mj, fatone s, roth ej. validity and reliability of the berg balance scale for community-dwelling persons with lower limb amputation. arch phys med rehabil. 2013; 94(11): 2194-2202. doi:10.1016/j.apmr.2013.07.002 https://doi.org/10.33137/cpoj.v4i1.35297 https://archive.org/details/hcfacommonproced00unit/page/n9/mode/2up https://archive.org/details/hcfacommonproced00unit/page/n9/mode/2up 7 yazgan a, kutlutürk s, lechler k. clinical outcomes comparing two prosthetic knee designs in individuals with unilateral transfemoral amputation in turkey. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.8. https://doi.org/10.33137/cpoj.v4i1.35297 issn: 2561-987x clinical outcomes comparing two prosthetic knee designs yazgan et al. 2021 cpoj 19.gouelle a, highsmith mj. instrumented four square step test in adults with transfemoral amputation: test-retest reliability and discriminant validity between two types of microprocessor knees. sensors. 2020; 20(17): 4782. doi:10.3390/s20174782 20.kristensen mt, nielsen ao, topp um, jakobsen b, nielsen kj, juel larsen k, et al. number of test trials needed for performance stability and interrater reliability of the one leg stand test in patients with a major non-traumatic lower limb amputation. gait posture. 2014; 39(1): 424-429. doi:10.1016/j.gaitpost.2013.08.017 21. singh sj, puhan ma, andrianopoulos v, hernandes na, mitchell ke, hill cj, lee al, camillo ca, troosters t, spruit ma, carlin bw. an official systematic review of the european respiratory society/american thoracic society: measurement properties of field walking tests in chronic respiratory disease. eur respir j. 2014 dec 1;44(6):1447-78. doi:10.1183/ 09031936.00150414 22. kücükdeveci aa, mckenna sp, kutlay s, gürsel y, whalley d, arasil t. the development and psychometric assessment of the turkish version of the nottingham health profile. international journal of rehabilitation research. internationale zeitschrift fur rehabilitationsforschung. revue internationale de recherches de readaptation. 2000 mar 1;23(1):31-8. doi:10.1097/00004356200023010-00004 23.safaz i, yılmaz b, göktepe as. reliability and validity of satisfaction with prosthesis (satpro) questionnaire in patient with lower limb amputation. nobel med. 2010; 6(3): 9-12. 24.prinsen ec, nederhand mj, olsman j, rietman js. influence of a user-adaptive prosthetic knee on quality of life, balance confidence, and measures of mobility: a randomised cross-over trial. clin. rehabil. 2015 ;29(6): 581-91. doi:10.1177/ 0269215514552033 25.nederhand mj, asseldonk ehfv, kooij h, rietman hs. dynamic balance control (dbc) in lower leg amputee subjects; contribution of the regulatory activity of the prosthesis side. clin biomech. 2012; 27(1): 40-45.doi:10.1016/j.clinbiomech.2011.07. 008 26.ülger ö, topuz s, bayramlar k. effects of a hydraulic knee joint on energy consumption, gait and patient satisfaction in transfemoral amputees. fizyoter rehabil. 2009; 20(3): 169-177. 27.lythgo n, marmaras b, connor h. physical function, gait, and dynamic balance of transfemoral amputees using two mechanical passive prosthetic knee devices. arch phys med rehabil. 2010; 91(10): 1565-1570. doi:10.1016/j.apmr.2010.07.014 28.wilken jm, roy cw, shaffer sw, patzkowski jc, blanck rv, owens jg, et al. physical performance limitations after severe lower extremity trauma in military service members. j. orthop. trauma. 2018; 32(4): 183-9. doi:10.1097/bot.0000000000001103 29.kahle jt, tyler dk, highsmith mj. comparative effectiveness of an adjustable transfemoral prosthetic interface accommodating volume fluctuation: case study. technol innov. 2016; 18(2-3): 175183. doi:10.21300/18.2-3.2016.175 30.kamali m, karimi mt, eshraghi a, omar h. influential factors in stability of lower‐limb amputees. am j phys med rehabil. 2013; 92(12): 1110‐18. doi:10.1097/phm.0b013e31829b4b7a 31.demet k, martinet n, guillemin f, paysant j, andre jm. health related quality of life and related factors in 539 persons with amputation of upper and lower limb. disabil rehabil. 2003; 25(9): 480-486. doi:10.1080/0963828031000090434 32.pell jp, donnan pt, fowkes fg, ruckley cv. quality of life following lower limb amputation for peripheral arterial disease. eur j vasc surg. 1993; 7(4): 448-451. doi:10.1016/s0950821x(05)80265-8 33.burçak b, kesikburun b, köseoğlu bf, öken ö, doğan a. quality of life, body image, and mobility in lower-limb amputees using high-tech prostheses: a pragmatic trial. ann. phys. rehabil. med. 2021; 64(1): 101405. doi:10.1016/j.rehab.2020.03.016 34.azuma y, chin t, miura y. the relationship between balance ability and walking ability using the berg balance scale in people with transfemoral amputation. prosthetics and orthotics international. 2019; 43(4): 396-401. doi:10.1177/ 0309364619846364 35.barnett sd, heinemann aw, libin a, houts ac, gassaway j, sen-gupta s, et al. small n designs for rehabilitation research. journal of rehabilitation research & development. 2012; 49(1): 175-186. doi:10.1682/jrrd.2010.12.0242 https://doi.org/10.33137/cpoj.v4i1.35297 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 2 2020 research article davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v3i2.34610 1 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 research article using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users davies k.c1*, mcgrath m1, savage z2, stenson a2, moser d1, zahedi s1 1 blatchford group, unit d antura, bond close, basingstoke, rg24 8pz, uk. 2 sheffield mobility & specialised rehabilitation centre, northern general hospital, sheffield, uk. introduction excessive sweating at the residual limb affects the quality of life of up to 70% of people with amputation and is one of the most common complaints reported by prosthetic users.1–3 indeed over 53% of lower limb amputees reported discomfort due to heat and/or perspiration4 while 66% felt that sweating impacted on their daily activities.5 comparatively, only 2.9% of the general population have been medically diagnosed as suffering from excessive sweating, or “hyperhidrosis”.6 sweating forms an effective way for reducing temperature and is an essential component of the body’s cooling process.7 when the skin is disrupted in some way, the body adapts in order to achieve the same cooling benefits and it is this adaptation that can prove problematic within prosthetics. people with lower limb amputation generally exert higher levels of energy during ambulation compared to able-bodied people. for unilateral transtibial amputees, this was around 16%,8 while with bilateral transtibial amputations, it is closer to 40%.9 consequentially, body open access volume 3, issue 2, article no.1. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: excessive sweating of the residual limb has a substantial effect on the daily activities of people with lower limb amputation. prosthetic liners offer protection and comfort to sensitive areas but often exacerbate perspiration. they act as insulators, trapping sweat on the skin’s surface to the detriment of skin health. recently, liners with perforations have been developed, allowing the moisture to escape. the goal of this study was to assess the impact of such liners. methods: a sample group of 13 patients with unilateral transtibial amputation, who wore a perforated liner (pl) as part of their current prescription, was compared to 20 control patients who wore nonperforated liners (npl). during their routine appointments, they completed a survey of scientifically validated outcome measures relating to their limb health, pain and the impact on daily life over a 12month period. results: patients using the pl had healthier residual limbs, reporting higher scores on questions relating to limb health, experiencing fewer skin issues (p<0.001) and estimating a 61.8% lower rating in perceived sweat (p=0.004). perhaps consequentially, there was a lower incidence of residual (p=0.012) and phantom (p=0.001) limb pain when compared to the control group. the prevalence of individual issues affecting the residual limbs of pl users was also lower. of the issues that remained, only 23% were attributed to sweating in pl users, compared to 49% for the npl group (p=0.066). pl users missed fewer days of work in the year (2.4 vs 11.6, p=0.267) and were also limited on fewer days (1.4 vs 75.4, p=0.009). conclusion: the use of perforated liners shows much promise within prosthetic care, significantly improving the health of the residual limb. the observed effects on perceived sweat reduction, residual skin health, pain levels and patient limitation suggest that perforated liners are highly beneficial to patients. article info received: july 16, 2020 accepted: august 29, 2020 published: september 3, 2020 citation davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i 2.34610 keywords prosthetics, sweat, prosthetic liner, perforated, amputation, residual limb health, silicone liner, amputee, dysvascular, temperature * corresponding author: k.c davies, blatchford group, unit d antura, bond close, basingstoke, rg24 8pz, uk. e-mail: katherine.davies@blatchford.co.uk orcid: https://orcid.org/0000-0003-2933-4365 https://doi.org/10.33137/cpoj.v3i2.34610 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i2.34610 https://doi.org/10.33137/cpoj.v3i2.34610 https://orcid.org/0000-0003-2933-4365 https://orcid.org/0000-0003-2933-4365 2 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 issn: 2561-987x using perforated liners in lower limb prosthesis users davies et al. 2020 cpoj temperature rises and the body reacts accordingly. a transtibial amputation also reduces the skin’s surface area by around 10-15%,10 so in order to achieve the same cooling effect, the rate of sweat production from the remaining surface must increase proportionally. the combination of these factors means that people with amputation may produce more sweat. prosthetic liners increase layers above the skin, offering protection and comfort to sensitive areas, but the materials are not breathable and act as insulators.11 this exacerbates the rise in temperature and traps the resultant sweat on the skin’s surface. sustained exposure to moisture has a detrimental effect on the skin,12 leaving it more susceptible to injury. skin disorders also become more problematic within the amputee population due to scar tissue and the high prevalence of vascular disease.13 this compromises blood flow, reducing healing capabilities and making the skin vulnerable.14,15 renshaw found that skin previously wetted with water was more likely to blister than when it was dry.16 in addition, hurkmans et al. found that sweat accumulation contributed towards skin irritation, perhaps even more so than infection.17 perhaps unsurprisingly then, skin disorders are prevalent in this vulnerable population18 with wound infection rates ranging between 13-40%19 following amputation and residual limb pressure ulcers causing the majority of re-amputations.20–22 various approaches have been trialled to improve excessive perspiration and heat,4 from the use of commercial or prescription anti-perspirants23 to more extreme options such as botulinum toxin injections.24,25 more prosthetic-specific solutions have also been tried and evaluated.26 wernke et al. investigated the smarttemp liner27 (ohio willowwood, mt sterling, oh, usa), which uses phase change material in order to store and release heat energy. the liner effectively reduced the initial temperature of the residual limb and therefore the volume of sweat produced. however, these materials have a limit on the amount of cooling they provide28 and in another study29 thermally conductive silicone did not result in a significant improvement in climate control over plain silicone liners. more recently, a liner with perforations has been developed (silcare breathe, blatchford, hampshire, uk) allowing moisture to escape and keeping the residual limb dry.30 these liners reduced the prevalence of sweat remaining on the skin in all participants during trials30 and in published case studies.31 evidence has suggested they are effective in the management of wounds and beneficial to residuum skin health, especially when used in combination with elevated vacuum.31 this study sought to determine the efficacy of perforated prosthetic liners for the purpose of sweat management, investigating what impact, if any, this made on patient outcomes. methodology evaluated technology this study examines the effects of a perforated liner (pl silcare breathe, blatchford products ltd., hampshire, uk)i,ii on patient outcome measures and residual limb health. it differs from previous silicone designs because it incorporates perforations along the length, and at the distal end, with the intention of improving skin interface microclimate control and hygiene of the residual limb (figure 1). figure 1: a cross-sectional image of the silcare breathe liner (blatchford).i,ii moisture is transported away from the skin through perforations located along the sides and at the distal end of the liner. these perforations allow moisture produced by the body to be transported to the outside of the liner, so that it doesn’t remain on the surface of the skin. moisture is then readily absorbed by the fabric on the outside of the liner, rather than by the silicone, so that it does not migrate back towards the skin and the liner can be more easily cleaned. participants suitable candidates (n=41) for the study were identified and approached by their prosthetists during routine appointments at northern general hospital in sheffield. the cohort was then divided into pl users and a control group who wore conventional non-perforated liners (npl). participants had to have a transtibial amputation and were required to have been using their current prescription for a minimum of 12 months. all participants were established prosthesis users with a mobility level of k2 or above and were able to read and write in english, with sufficient cognitive ability. all patients provided informed, written consent. the study was approved by the clinical effectiveness unit at sheffield teaching hospitals. no interventional actions were taken and the ethics of the study conformed with the world health organisation declaration of helsinki.32 data collection and measures all participants completed a survey of scientifically validated outcome measures during routine appointments. the perforations transport moisture away from the skin silicone liner (3.7mm mid-thickness) material on outside of the liner absorbs moisture, preventing it from travelling back to the skin’s surface residual limb socket https://doi.org/10.33137/cpoj.v3i2.34610 3 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 issn: 2561-987x using perforated liners in lower limb prosthesis users davies et al. 2020 cpoj surveys were comprised of selected sections of the patient evaluation questionnaire33 (peq); a clinically validated patient-reported outcome measure that has been used successfully to analyse the use of prosthetic liners in previous studies.34–36 this questionnaire is organised into independent functional domain subsections,37 where the patient indicates a score out of 100 using a visual analogue scale (vas) for each individual question. every question relates to the previous four weeks and the overall average gives the score for the subset. for this study, the residual limb health subset was used, made up of questions about sweat inside the liner, smelliness, swelling, rashes, ingrown hairs and blisters. as well, individual peq questions relating to frequency, intensity and ‘bothersomeness’ of residual and phantom limb pain were included. following peq scoring, lower scores indicated worse symptoms (e.g. 0 = extremely intense, 100 = extremely mild). for frequency of pain, a seven-point multiple choice format was used, rather than the visual analogue scale. these choices were “never", "only once or twice", "a few times (about once/week)", “fairly often (2-3 times/week)", "very often (4-6 times/week)", "several times every day" and "all the time or almost all the time". in order to allow a quantifiable comparison between groups, these responses were assigned a score from 1 (least frequent) to 7 (most frequent), from which the mean and sd were calculated. in addition, questions specifically designed for this study were included in the surveys which related to the previous 12 months. these enquired about excessive sweating, number of socket adjustments required, what issues the patient experienced on their residual limb and the number of days work that had been missed or limited because of issues caused by sweating. study group participants also filled out the survey retrospectively, with regards to their previous prescription. due to the retrospective nature of these responses, it was thought that results might be unreliable and affected by bias. while the retrospective responses were comparable to those of the control group, the principal comparison reported in this work is between the study group’s current responses and responses from the control group. data processing and analysis residual limb issues were categorised into conditions and the frequency of each was recorded as a percentage of the population so that an objective comparison could be made. participants were asked to estimate what percentage of their issues they attributed directly to sweat. this figure was then multiplied by the total number of issues each participant suffered from, to calculate the number of issues that each participant attributed to sweating. for all vas and numerical responses, the mean and standard deviation for each outcome measure were found and used for comparisons. data were tested for normality using the shapiro-wilk test. homogeneity of variance was assessed using f tests for normal data and a fligner-killeen test in cases where the data were not normal. dependent on the outcome, comparisons of means were made using ttests, wilcoxon tests or kruskal-wallis tests. for ordinal or nominal data (e.g. frequency of pain and prevalence of issues), comparisons were made using a chi-squared analysis. for all tests, p<0.05 indicated significance. results demographics of the overall cohort (n=41), 21 were identified as pl users. out of these, eight patients did not use the liner consistently, or discontinued use, and were excluded. of the remaining 13 participants, ten were male and three were female (age: 49 (sd=10) years; weight: 96 (sd=26) kg. nine had used silicone liners in their previous prescription and four used conventional pelite liners in conjunction with a suspension sleeve; all now wore perforated silicone liners with either suction or pinlock suspension (table 1). table 1: study group participant demographics. gender age (years) weight (kg) aetiology previous prescription (suspension) current prescription (suspension) pl01 m 57 92.5 unknown pelite liner and silo sheath (sleeve) blatchford silcare breathe cushion (suction) pl02 f 37 103 infection pelite liner and silipos sock (sleeve) blatchford silcare breathe (pinlock) pl03 m 54 112 trauma össur liner (pinlock) blatchford silcare breathe (pinlock) pl04 m 41 100.6 trauma blatchford liner (pinlock) blatchford silcare breathe (pinlock) pl05 f 55 77 congenital össur liner (pinlock) blatchford silcare breathe (pinlock) pl06 m 35 81.4 infection pelite liner (sleeve) blatchford silcare breathe (pinlock) pl07 m 62 99.3 unknown össur liner (pinlock) blatchford silcare breathe (pinlock) pl08 m 57 82.1 vascular össur liner (pinlock) blatchford silcare breathe (pinlock) pl09 f 38 79.2 trauma blatchford cushioned liner (suction) blatchford silcare breathe (pinlock) pl10 m 46 88.2 trauma alps liner (pinlock) blatchford silcare breathe (pinlock) pl11 m 59 104.8 trauma alps liner (pinlock) blatchford silcare breathe (pinlock) pl12 m 59 169.6 vascular pelite liner (sleeve) blatchford silcare breathe cushion (suction) pl13 m 41 62.9 pain management blatchford cushioned liner (suction) blatchford silcare breathe (pinlock) mean 49.3 96.4 sd 9.8 25.9 https://doi.org/10.33137/cpoj.v3i2.34610 4 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 issn: 2561-987x using perforated liners in lower limb prosthesis users davies et al. 2020 cpoj the control group was made up of the remaining 20 participants, 16 male and four female (age: 56 (sd=15) years; weight: 90 (sd=22) kg). all of them wore silicone prosthetic liners, using either suction or pinlock suspension, from various distributors (table 2). residual limb health and pain the mean residual limb health score for the pl group (75.0 (sd=22.9)) was significantly greater than that of the npl group (58.4 (sd=22.7); p=0.046). for each of the six questions that constitute this subset, mean responses were higher for the pl group, indicating that problems were less prevalent, and that the limb was healthier. for two questions – the amount of sweat in their liner (p=0.004) and how smelly their limb was (p=0.012) – the difference in response reached statistical significance (figure 2). indeed, if the scale is inverted (so that a higher number indicates a higher quantity of sweat) pl users reported 61.8% less sweat remaining on the limb than the control group (p=0.004). when asked a binary yes/no question about whether they perceived the amount they sweat to be excessive (table 3), 85% of the control group answered yes. in the study group, this was significantly less (p<0.001) with only 15% reporting excessive sweating. it is also worth noting that these participants added the caveat that this occurred only very rarely. pl users reported less intense residual limb pain (66.3 (sd=32.0)) and less intense phantom limb pain (48.6 (sd=35.4)) than the npl control group (38.5 (sd=29.9)) and 37.2 (sd=37.0) respectively). while neither of these changes reached statistical significance (p=0.071 and p=0.360 respectively), how “bothersome” participants found pain in their residual limb did, with the pl group reporting that it was less bothersome (68.5 (sd=30.9)) than the npl group (38.8 (sd=32.0), p=0.045). significant differences were observed for the pl group, compared to the npl group, in the frequency of residual limb pain (2.7 (sd=1.7) and 4.2 (sd=1.9), respectively; p=0.032) and the frequency of phantom limb pain (2.8 (sd=1.6) and 4.3 (sd=2.1), respectively; p=0.042). these results are shown in figure 3 and figure 4. a clear skew towards lower frequencies in the pl group here, indicates fewer occurrences of pain. issues at the residuum the mean number of residual limb issues reported was significantly higher in the npl control group (2.8 (sd=1.5)) than the pl group (1.2 (sd=1.0), p<0.001). issues that were reported by both groups were chaffing, blisters, rashes, heat rash and pressure sores, with chaffing being the most prevalent issue in both groups (figure 5). the frequency of all issues was lower in the pl group; the percentage of the population affected by chaffing differed significantly from 80% in the control group, to 46% in the pl group (p=0.002). table 2: control group participant demographics. gender age (y) weight (kg) aetiology prescription (suspension) npl01 f 49 80.0 infection össur liner (pinlock) npl02 m 76 83.5 trauma össur liner (pinlock) npl03 m 67 91.8 trauma össur liner (pinlock) npl04 m 66 106.4 infection alps liner (pinlock) npl05 m 30 69.3 trauma össur liner (pinlock) npl06 m 70 79.6 trauma össur liner (pinlock) npl07 m 31 83.6 infection alps liner (pinlock) npl08 m 81 71.8 vascular blatchford liner (pinlock) npl09 m 59 94.6 trauma alps liner (pinlock) npl10 f 57 84.6 trauma össur liner (pinlock) npl11 m 70 74.4 vascular össur liner (pinlock) npl12 m 56 97.6 trauma blatchford liner (pinlock) npl13 m 47 85.0 trauma alps liner (pinlock) npl14 m 63 97.5 unknown ottobock cushioned liner (suction) npl15 m 48 166.0 unknown alps liner (pinlock) npl16 m 47 67.0 vascular alps liner (pinlock) npl17 m 52 103.0 unknown össur cushioned liner (suction) npl18 f 31 70.0 trauma blatchford liner (pinlock) npl19 m 79 89.0 trauma ottobock custom silicone liner (pinlock) npl20 f 47 116.0 trauma össur liner (pinlock) mean 56.3 90.5 sd 15.4 22.1 table 3: results of additional questions included within survey. p values in bold text indicate significance (p<0.05). during the past 12 months… pl group (mean (sd)) npl group (mean (sd)) p value do you currently suffer from excessive sweating? yes: 2 (15.4%) no: 11 (84.6%) yes: 17 (85.0%) no: 3 (15.0%) <0.001 approximately, how many socket adjustment appointments have you required? 1.8 (1.9) 2 (1.4) 0.610 what % of your residual limb issues (skin/tissue breakdown) would you attribute to sweating? 22.7 (33.2) 49.0 (39.5) 0.066 have you taken any days off work, or were housebound, for skin issues? if so, how many days? n = 12 2.4 (6.0) n = 16 11.6 (21.9) 0.267 have you limited the use of your prosthesis and activities due to discomfort caused by sweating? if so, how many days? n = 12 1.4 (2.9) n = 17 75.4 (130.6) 0.009 https://doi.org/10.33137/cpoj.v3i2.34610 5 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 issn: 2561-987x using perforated liners in lower limb prosthesis users davies et al. 2020 cpoj the occurrence of blisters also changed significantly from 45% in the control group to 15% in the pl group (p=0.032); and differences in heat rashes (50% vs 23%) and fungal infection (20% vs 0%) approached significance (p=0.052 and 0.071 respectively). although not significant, the occurrence of pressure sores changed from 35% in the control group to 15% of the pl group (p=0.138). least prevalent issues within the control group (fungal infection, callusing, abscess) were not seen at all in the pl group. figure 2: residual limb health peq subset score for the npl control group (grey) and the pl group (green). the error bars indicate ± one standard deviation from the mean. asterisks (*) indicate a statistically significant change (p<0.05). 0 20 40 60 80 100 how much sweat? smelliness swelling rashes ingrown hairs blisters mean limb health p a rt ic ip a n t s c o re < e x tr e m e i s s u e s n o i s s u e s > residual limb health peq score npl group pl group 0 10 20 30 40 50 never only once or twice a few times (about once/week) fairly often (2-3 times/week) very often (4-6 times/week) several times every day all the time p e rc e n ta g e o f p o p u la ti o n ( % ) frequency of residual limb pain pl group npl group figure 3: peq pain subset results for the frequency of the residual limb pain experienced by both pl (striped) and npl (grey) groups. a skew to the left indicates less pain. the difference between the group was significant (p<0.05) with pl users experiencing less pain. 0 10 20 30 40 50 never only once or twice a few times (about once/week) fairly often (23 times/week) very often (4-6 times/week) several times every day all the timep e rc e n ta g e o f p o p u la ti o n ( % ) frequency of phantom limb pain pl group npl group figure 4: peq pain subset results for the frequency of phantom limb pain experienced by both pl (striped) and npl (grey) groups. a skew to the left indicates less pain. the difference between groups was significant (p<0.05) with pl users experiencing less pain. https://doi.org/10.33137/cpoj.v3i2.34610 6 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 issn: 2561-987x using perforated liners in lower limb prosthesis users davies et al. 2020 cpoj when patients were asked to rate how many of their issues they attributed directly to sweating, the percentage was lower for the pl group (table 3). the control group estimated that on average, 49% of all issues were due to sweating, whereas the pl group attributed only 23% to sweat (figure 6). figure 6: the mean number of issues experienced by patients at their residual limb, and the percentage of those issues that were attributed to sweating (grey) or to other causes (green). exact percentages are indicated within bars. this result did not reach statistical significance (p=0.066) due to the high variability between patients. when using the percentages to calculate the number of issues attributed to sweat however, the control group subjects averaged 1.7 (sd=1.7), while in the study group this was 0.3 (sd=0.5); a result that was significant (p=0.007). the number of workdays missed was lower in the pl group with a mean of 2.4 (sd=6.0) days taken off work due to issues compared to 11.6 (sd=21.9) in the control group (p=0.267, table 3). the number of days limited by issues surrounding the prosthesis was significantly less, with the pl group limited a mean of 1.4 (sd=2.9) days and the control group 75.4 (sd=130.6) days (p=0.009). discussion this report investigated the clinical consequences of perforated prosthetic liners based on the feedback provided by study participants and a comparable control group. while patient-reported outcome measures can be subjective, large trends in the data can imply significant changes in patient outcome over a wider population. the results suggest perforated liner users have significantly more successful patient outcomes and experiences through better residual limb health and less frequent outbursts of pain. overall, the study group showed better peq residual limb health scores (figure 2). within this subset, the score for every question was higher, indicating an increase in health and therefore a reduction of each adverse factor. significant changes were seen in the amount of sweat present on the limb as well as in the limb’s odour. given that malodour is a direct result of the bacterial secretions following a transformation of the compounds found in sweat,38 it seems logical that a decrease in odour would be attributable to a decrease in the amount of sweat inside the liner. the design of the perforated liner is such that once the moisture migrates to the outside of the liner, it is absorbed by the fabric lining. to this end, the odour is more likely to develop on the outside of the liner, and can be easily washed, instead of impregnating into the inner silicone where it lingers. 0 20 40 60 80 100 chaffing heat rash blister pressure sore rash fungal infection callusing abscess p e rc e n ta g e o f p o p u la ti o n ( % ) occurrence of issues at the residual limb npl group pl group figure 5: percentage of the group populations that were affected by individual issues at the residual limb. the npl group are indicated in grey and the pl group in green. asterisks (*) indicate statistically significant results (p<0.05) while obelisks (†) indicate results that approached significance (0.05<p<0.10). 49% 23% 51% 77% 0 0.5 1 1.5 2 2.5 3 npl group pl group n u m b e r o f is s u e s mean number of issues experienced by patients at their residual limb issues attributed to other causes issues attributed to sweating https://doi.org/10.33137/cpoj.v3i2.34610 7 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 issn: 2561-987x using perforated liners in lower limb prosthesis users davies et al. 2020 cpoj for clarification, it is worth highlighting that this study used patient reported outcome measures and so reported the patient’s perception of whether they sweat to excess and how much remained on their limb. this study cannot comment on whether the type of prosthetic liner used affects the actual quantity of sweat produced. however, sweat being transported away from the skin is likely to have positively affected the amount of sweat perceived by participants using the perforated liner, as well as contributing towards a healthier environment for the residual limb. there were notable differences in scores relating to rashes and blisters within the peq subset (figure 2). again, these are largely foreseeable. rashes can be caused by infection, a known risk factor in the bacteria-rich environment caused by trapped sweat, but they can also be the result of friction.39 additional lubrication causes movement at the socket11 and moisture increases the coefficient of friction between the skin and materials in contact with it,40 imposing greater risk of tissue breakdown such as blisters. it follows then, that removing sweat from the skin’s surface might reduce the amount of irritation caused by movement at the residuumsocket interface, therefore decreasing the likelihood of rashes and blisters. scores regarding swelling and ingrown hairs also showed less prevalence in the pl group, but the difference was small, suggesting that climate control affected these to a lesser extent. however, previous studies41 have drawn links between water exposure and resulting inflammation of the skin, so it might be of interest to explore further the relationship of climate control to individual factors and conditions that affect the residual limb. for the peq questions relating to pain, both residual and phantom limb pain were significantly less frequent in the pl group (figure 3 and figure 4). the difference in residual limb pain might have been predicted due to the discomfort caused by physical skin conditions which were less prevalent. however, the cause of phantom limb pain, which occurs after up to 80% of amputations,42 is still a subject of speculation and continued investigations are needed.43 larbig et al.44 surmised that, along with other factors, physical pain following amputation was a risk factor for more intense phantom limb sensations, maybe providing some explanation of the reduction reported in this study. in addition, fuchs et al.45 measured significantly higher intensities of phantom limb pain in upper limb amputees with lower heat pain thresholds. although the difference in the intensity of phantom limb pain was not significant in this study, the suggested link between that and the temperature of the limb is an interesting one and may warrant further study. the proportional prevalence of specific skin conditions was consistent with that found in previous studies46,47 across both patient groups, however the frequency of issues was less with the use of the perforated liner. the reduction in the average number of skin issues in the study group reinforces the findings from a previous study.31 not only was the number of issues present at the residual limb less, but the same was true with the occurrence of more severe conditions. as previously discussed, less perspiration on the skin’s surface might result in lower rates of infection and irritation; but it may also contribute to a reduction in calluses and pressure sores by reducing movement of the liner. the formation of ulcers is included within the category of pressure sores, which are arguably one of the most serious issues that can occur, linked to vascular disease for which a large number of lower limb amputations are attributable.13 historically, complications with the skin of the residual limb limit prosthetic use, interfering not only with an established patient’s ability to ambulate, but also with the rehabilitation process of primary amputees. this limits participation, affecting quality of life48,49 and patient wellbeing,46 leading to negative implications for the physical, psychological and emotional condition of the patient. indeed primary patients who remained non-ambulatory for over 6 months were shown to have a much higher likelihood of developing complications,50 with several studies51–53 finding early prosthetic use in primary amputees had real benefits not just for the mental health of patients but for the subsequent outcome measures such as treatment compliance and prosthetic use. as such, it is important to minimise the time that patients spend without a prosthesis. gallagher et al.54 found one of the top three factors affecting amputee participation was climate. furthermore, pain in the residual and phantom limbs has been found to influence a patient’s ability of returning to work following amputation.55 within this study, pl users had fewer days of limited prosthetic use and a lower number of workdays missed. this, combined with the perception of improved climate control and limb health reported, would indicate an improvement in patient outcomes. it is worth noting, that while these results accounted for the active employment status of participants, the type of employment was not considered. the type of work may have affected the ability of the individuals to work given socket discomfort and therefore the number of days missed. the primary aim of this study was to identify the health effects of different liners on the residual limb. however, the implications that patient health and reduction in rehabilitation times have in terms of health and economic cost is well documented.56,57 in addition, days of work that are either missed by patients or are limited, affect not only the individual’s salary but can increase vulnerability in the face of redundancy or promotion opportunities.58the health economic benefits require further investigation, however, the possible larger scale implications of this treatment pathway only increase the clinical significance of this study. https://doi.org/10.33137/cpoj.v3i2.34610 8 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 issn: 2561-987x using perforated liners in lower limb prosthesis users davies et al. 2020 cpoj participants were selected by clinicians using inclusion criteria and asked to take part in the study during normal clinical visits. as this was not a blind recruitment process, it may have introduced a bias. the control group were selected at random from established patients attending the clinic, however the study group were selected because of their specific prescription. patients are likely to be using this prescription because of higher activity levels or past problems related to sweating; equally the control group could have a large range in activity levels. all participants were activity level k2 or above, however the activities of each patient were not recorded. although the data are likely to show a bias against perforated liners, potentially making the effects of this intervention more powerful, the lack of activity data is considered a large limitation of this study. participants were asked a binary question about whether or not they considered their sweating excessive. the percentage of participants who answered yes was significantly less in the study group compared to the control group (p<0.001, table 3). this is useful in that it provides an awareness of patient experience and satisfaction, but it does not show any variation between the patients that sweat to excess. although still subjective, the nature of the peq requires participants to quantify the amount they think they sweat, thereby accounting for participants who felt they fell somewhere in the middle. this question gave a similar result, with the study group reporting significantly higher scores in the peq questions relating to the quantity of sweat present (p=0.004) on the residual limb. both questions essentially give very similar data, but it could be argued that in this case, the peq provides more information. although many patients with lower limb amputations suffer from it, vascular disease is the aetiology of surprisingly few participants within this study. the slower healing capabilities of this demographic, means these patients are more likely to suffer from skin conditions18 and so the lack of vascular participants might mean the study is not representative of the overall amputee population. however, the study and control groups are comparable in this respect, and there is still a significant difference seen in the prevalence and type of skin conditions. one aspect of the study population that is of note, is the complete absence of one or more skin conditions on the residual limb in the study group (figure 5). this is a significant improvement; however, given the small sample size, the result is likely a false positive. if the number of participants had been larger, it is probable that these issues would have occurred, at least minimally, in both groups. there was a high variability in the percentage of issues that patients attributed to sweating, meaning that the result was not considered significant. this variation came from the balance between the number of issues caused by sweating compared with the total number of issues each participant experienced. for example, a patient may only have one issue, but it may be 100% the result of sweating. this variation calls into question the validity of the result. by multiplying the individual’s total number of issues by the percentage that they estimated were caused by sweat, the number of sweat resultant issues that each patient suffered from could be calculated. this showed a reduction in sweat related issues which did prove significant (p=0.007, table 3) and so it must be noted that although the percentages may not be significant on their own, when applied to the data on issues suffered by the individual, the result is valid (figure 6). it is possible that some patients may experience iatrogenic affects from the perforations, however this was not reported by any of the participants in the study. additional factors that could affect the outcome measures of this study included liner material and thickness, suspension type and socket comfort. the perforated liner used in this study is 3.7mm thick at its mid-point and so falls within the industry standard range (3mm to 6mm). although manufacturers use different material compositions, ali et al. found that the was no significant difference between the sweat complaints of patients using liners of different material and varying suspension method.59 nevertheless, it should be noted that all participants used either pinlock or suction suspension systems. socket comfort scores were not collected in this study, however the number of socket adjustments needed in the 12-month period was recorded (table 3). socket adjustments are often required if there is discomfort and so might indicate a level of socket comfort. the number of adjustments needed was comparable between groups, so this factor is unlikely to have had any significant impact on the results of this study. conclusion this study shows promising results for the use of perforated liners within prosthetic care, with significant differences being observed between the two patient groups. excessive sweating impacts many aspects of the patient’s life beyond just their physical health; resulting issues preventing prosthetic use and limiting patients’ mobility, in turn affecting their daily lives and causing frustration. perforated liners help to manage excessive sweat levels. improvements in patient health and the implications that this may have on quality of life often inform prescription guidelines, therefore technology that can positively impact these factors may prove highly beneficial. acknowledgements special thanks are extended to the clinical team at sheffield mobility and specialised rehabilitation centre and sheffield teaching hospitals, for participation and the collection, and initial collation of data for this study. https://doi.org/10.33137/cpoj.v3i2.34610 9 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 issn: 2561-987x using perforated liners in lower limb prosthesis users davies et al. 2020 cpoj declaration of conflicting interests the authors are full time employees of blatchford, the manufacturer of the prosthetic liner evaluated in this study. author contribution katherine c. davies: data analysis, writing original, review and editing mike mcgrath: conceptualisation, data analysis, writing original, review and editing zoe savage: conceptualisation, data collection alison stenson: conceptualisation, data collection david moser: review and editing saeed zahedi: review and editing sources of support authors are employees of blatchford products ltd. ethical approval all patients provided informed, written consent. the study was approved by the clinical effectiveness unit at sheffield teaching hospitals. no interventional actions were taken and the ethics of the study conformed with the world health organisation declaration of helsinki. references 1.meulenbelt he, geertzen jh, jonkman mf, dijkstra pu. determinants of skin problems of the stump in lower-limb amputees. arch phys med rehabil. 2009; 90: 74–81. doi:10.1016/j.apmr.2008.07.015. 2. berke gm, fergason j, milani jr, hattingh j, mcdowell m, nguyen v, et al. comparison of satisfaction with current prosthetic care in veterans and servicemembers from vietnam and oif/oef conflicts with major traumatic limb loss. j rehabil res dev. 2010; 47. doi:10.1682/jrrd.2009.12.0193. 3.hagberg k, brånemark r. consequences of non-vascular transfemoral amputation: a survey of quality of life, prosthetic use and problems. prosthet orthot int. 2001; 25: 186–94. doi:10.1080/03093640108726601. 4.ghoseiri k, safari mr. prevalence of heat and 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doi:10.1097/jpo.0000000000000070. 28.mondal s. phase change materials for smart textiles – an overview. appl therm eng. 2008; 28: 1536–50. doi:10.1016/j.applthermaleng.2007.08.009. 29.williams rj, washington ed, miodownik m, holloway c. the effect of liner design and materials selection on prosthesis interface heat dissipation. prosthet orthot int. 2018; 42: 275–9. doi:10.1177/0309364617729923. 30.gallego a, mccarthy j, mcgrath m, kercher a, zahedi s, moser d. patient trial evaluation of a perforated, pin-lock prosthetic liner for sweat management. can prosthet orthot j. 2018; 1. doi:10.33137/cpoj.v1i2.32011. 31.mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. can prosthet orthot j. 2019; 1. doi:10.33137/cpoj.v2i1.32723. 32.association wm. world medical association declaration of helsinki. ethical principles for medical research involving human subjects. bull world health organ. 2001; 79: 373. doi:pmc2566407. 33.legro mw, reiber gd, smith dg, del aguila m, larsen j, boone d. prosthesis evaluation questionnaire for persons with lower limb amputations: assessing prosthesis-related quality of life. arch phys med rehabil. 1998; 79: 931–938. doi:10.1016/s00039993(98)90090-9. 34.klute gk, berge js, biggs w, pongnumkul s, popovic z, curless b. vacuum-assisted socket suspension compared with pin suspension for lower extremity amputees: effect on fit, activity, and limb volume. arch phys med rehabil. 2011; 92: 1570–1575. doi:10.1016/j.apmr.2011.05.019. 35.coleman kl, boone da, laing ls, mathews de, smith dg. quantification of prosthetic outcomes: elastomeric gel liner with locking pin suspension versus polyethylene foam liner with neoprene sleeve suspension. j rehabil res dev. 2004; 41. doi:10.1682/jrrd.2004.04.0591. 36.brunelli s, delussu as, paradisi f, pellegrini r, traballesi m. a comparison between the suction suspension system and the hypobaric iceross seal-in® x5 in transtibial amputees. prosthet orthot int. 2013; 37: 436–444. doi:10.1177/0309364613476531. 37.boone da, coleman kl. use of the prosthesis evaluation questionnaire (peq). jpo j prosthet orthot. 2006; 18: p68–p79. doi:10.1097/00008526-200601001-00008. 38.james ag, casey j, hyliands d, mycock g. fatty acid metabolism by cutaneous bacteria and its role in axillary malodour. world j microbiol biotechnol. 2004; 20: 787–793. doi:10.1007/s11274-004-5843-8. 39.mcmullen e, gawkrodger dj. physical friction is underrecognized as an irritant that can cause or contribute to contact dermatitis. br j dermatol. 2006; 154: 154–6. doi:10.1111/j.13652133.2005.06957.x. 40.gerhardt l-c, strässle v, lenz a, spencer n, derler s. influence of epidermal hydration on the friction of human skin against textiles. j r soc interface. 2008; 5: 1317–28. doi:10.1098/rsif.2008.0034. 41.ramsing dw, agner t. effect of water on experimentally irritated human skin. br j dermatol. 1997; 136: 364–7. doi:10.1046/j.1365-2133.1997.d01-1201.x. 42.flor h. phantom-limb pain: characteristics, causes, and treatment. lancet neurol. 2002; 1: 182–9. doi:10.1016/s14744422(02)00074-1. 43.weeks sr, anderson-barnes vc, tsao jw. phantom limb pain: theories and therapies. the neurologist. 2010; 16: 277–286. doi:10.1097/nrl.0b013e3181edf128. 44. larbig w, andoh j, huse e, stahl-corino d, montoya p, seltzer ze, et al. preand postoperative predictors of phantom limb pain. neurosci lett. 2019; 702: 44–50. doi:10.1016/j.neulet.2018.11.044. 45.fuchs x, diers m, trojan j, kirsch p, milde c, bekraterbodmann r, et al. phantom limb pain intensity is associated with generalized hyperalgesia. biorxiv. 2019: 538207. doi:10.1101/538207. 46.dudek nl, marks mb, marshall sc. skin problems in an amputee clinic. am j phys med rehabil. 2006; 85: 424–429. doi:10.1097/01.phm.0000214272.01147.5a. 47.afzal s, bukhari b, waqas m, munir a. skin problems of amputee using lower limb prosthesis. rawal med j. 2019; 44: 61– 63. 48.davie-smith f, paul l, stuart w, kennon b, young r, wyke s. the influence of socio-economic deprivation on mobility, participation, and quality of life following major lower extremity amputation in the west of scotland. eur j vasc endovasc surg. 2019; 57: 554–60. doi:10.1016/j.ejvs.2018.10.011. https://doi.org/10.33137/cpoj.v3i2.34610 11 davies k.c, mcgrath m, savage z, stenson a, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.1. https://doi.org/10.33137/cpoj.v3i2.34610 issn: 2561-987x using perforated liners in lower limb prosthesis users davies et al. 2020 cpoj 49.langford j, dillon mp, granger cl, barr c. physical activity participation amongst individuals with lower limb amputation. disabil rehabil. 2019; 41: 1063–70. doi:10.1080/09638288.2017.1422031. 50.uustal h. prosthetic rehabilitation issues in the diabetic and dysvascular amputee. phys med rehabil clin. 2009; 20: 689–703. doi:10.1016/j.pmr.2009.06.014. 51.schon lc, short kw, soupiou o, noll k, rheinstein j. benefits of early prosthetic management of transtibial amputees: a prospective clinical study of a prefabricated prosthesis. foot ankle int. 2002; 23: 509–14. doi:10.1177/107110070202300607. 52.folsom d, king t, rubin jr. lower-extremity amputation with immediate postoperative prosthetic placement. am j surg. 1992; 164: 320–2. doi:10.1016/s0002-9610(05)80896-7. 53.munin mc, de guzman mce, boninger ml, fitzgerald sg, penrod le, singh j. predictive factors for successful early prosthetic ambulation among lower-limb amputees. j rehabil res dev. 2001; 38: 379–384. issn:0748-7711. 54.gallagher p, o’donovan m-a, doyle a, desmond d. environmental barriers, activity limitations and participation restrictions experienced by people with major limb amputation. prosthet orthot int. 2011; 35: 278–84. doi:10.1177/0309364611407108. 55.millstein s, bain d, hunter ga. a review of employment patterns of industrial amputees—factors influencing rehabilitation. prosthet orthot int. 1985; 9: 69–78. doi:10.3109/03093648509164708. 56. bickers dr, lim hw, margolis d, weinstock ma, goodman c, faulkner e, et al. the burden of skin diseases: 2004: a joint project of the american academy of dermatology association and the society for investigative dermatology. j am acad dermatol. 2006; 55: 490–500. doi:10.1016/j.jaad.2006.05.048. 57. lim hw, collins sa, resneck jr js, bolognia jl, hodge ja, rohrer ta, et al. the burden of skin disease in the united states. j am acad dermatol. 2017; 76: 958-972.e2. doi:10.1016/j.jaad.2016.12.043. 58.strauser dr, lustig dc, uruk ac. differences in career thoughts between individuals with and without disability: do they really exist? j appl rehabil couns. 2004; 35: 25–31. doi:10.1891/0047-2220.35.2.25. 59.ali s, abu osman na, naqshbandi mm, eshraghi a, kamyab m, gholizadeh h. qualitative study of prosthetic suspension systems on transtibial amputees’ satisfaction and perceived problems with their prosthetic devices. arch phys med rehabil. 2012; 93: 1919–23. doi:10.1016/j.apmr.2012.04.024. manufacturers’ documentation ihttps://www.blatchford.co.uk/products/silcare-breathe-cushionliner/ iihttps://www.blatchford.co.uk/products/silcare-breathe-lockingliner/ https://doi.org/10.33137/cpoj.v3i2.34610 https://www.blatchford.co.uk/products/silcare-breathe-cushion-liner/ https://www.blatchford.co.uk/products/silcare-breathe-cushion-liner/ https://www.blatchford.co.uk/products/silcare-breathe-locking-liner/ https://www.blatchford.co.uk/products/silcare-breathe-locking-liner/ rasmussen l, rodriguez s, bowers m, smith d, martino g, rizzo l, scheiber c, d’almeida j, dillis c. adjustable liners and sockets for prosthetic devices. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32048 1 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) adjustable liners and sockets for prosthetic devices lenore rasmussen1*, simone rodriguez1, matthew bowers1, damaris smith1, greig martino2, livia rizzo3, cole scheiber4, jesse d’almeida5, curran dillis6 1 ras labs, synthetic muscle tm for prosthetics & robotics, usa. 2 united prosthetics (upi), boston, massachusetts, usa. 3 harvard medical school, medscience program, usa. 4 biology, tufts university, massachusetts, usa. 5 robotics engineering, worcester polytechnic institute, massachusetts, usa. 6 hingham hs, robotics captain, usa. * email: rasmussl@raslabs.com doi: https://doi.org/10.33137/cpoj.v1i2.32048 introduction ras labs’ synthetic muscle™ will allow amputees to continue their active lives without needing to adjust the fitting of their prosthetic device(s) throughout the day. this technology promises to resolve major issues facing amputees, most notably the pain of prosthetic slippage and tissue breakdown. synthetic muscle™, comprising electroactive polymers (eaps), actively expand or contract at low voltages, while offering impact resistance and pressure sensing, all in one integrated solution. the main objectives of this project is to determine the feasibility of the eap pads incorporated into prosthetic liners or sockets and to create prototypes of these eap based shape-morphing pad systems. in collaboration with upi, testing of these eap based pads located in strategic areas of the socket was initiated with customers (bk and ak) for evaluation and feedback. characterization of synthetic muscle™ as dual use pressure sensors was initiated. this is a continuation ras labs’ dynamic prosthetic pad project, which demonstrated how the volume of the eap can be changed from applying a low voltage and operating temperatures for use in adjustable prosthetic liners and sockets 1-8. methods the eap networks were developed by polymerization of ionic monomers with specialized cross-linking agents. the desired pore sizes and elasticity in the final networks were achieved by controlling the cross-link density and aqueous solvation during polymerization, followed by equilibration of the eap in electrolyte solution to its final volume. pad designs were assembled and tested over contraction and expansion cycles at 1.5 v. a pre-step of expansion for 1 hour (not shown in figures) was performed followed by contraction for 4 hours under load, an expansion cycle for 30 minutes under static load, and an expansion for 5+ hours under 1 hz cyclic on-off pressure load to mimic ambulation in the socket. the electroactivity of these pad designs were tested by attaching the reservoir and eap electrodes to the corresponding polarity for 2-hour contraction and expansion cycles over 1.5v, 3v, 6v, and 9v. the dimensions were measured after each cycle to follow the change in height. results all of the eap based pad design prototypes performed at 1.5 v, with the 3 lb. testing set-up having a higher pound per square inch than the 5 lb. testing set-up due to the different sizes of the eap pads. contraction occurred over the first 5 hours, static load, followed by 30 minutes expansion, static load, followed by 5+ hours expansion under cyclic load at 1 hz to mimic ambulation. the cyclic load is to demonstrate actuation during daytime use (after a long contraction cycle). in use, these eap based pads will be contracted overnight at low voltage, then either allowed to expand back to their neutral state at 0 v or the electric input reversed to provide for expansion. particularly under cyclic load, expansion is readily observable even within the first cycle, which would be needed for the eap pads to quickly meet and match void changes from shrinkage of the residual limb if there is a fast change. from the testing at 1.5 v, 3 v, 6 v, and 9 v with 2-hour cycles, all voltage levels showed electroactive actuation. the 3 v, 6 v and 9 v testing typically demonstrating incrementally more shape-morphing in both expansion and contraction; however, the 9 v testing produced some artifacts as well with distinct localized effects. as the development of sensing in the eap progressed, the construction methods improved. a challenge was consistency between the pads themselves, resulting in data that could not be regarded as overly reliable. the solution was to create mailto:rasmussl@raslabs.com https://doi.org/10.33137/cpoj.v1i2.32048 rasmussen l, rodriguez s, bowers m, smith d, martino g, rizzo l, scheiber c, d’almeida j, dillis c. adjustable liners and sockets for prosthetic devices. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32048 2 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) a specific system of manufacturing that was as close as possible for each pad, including: 3d printed molds for the silicone casings and 3d printed pads for a point electrode. extensive design experiments were performed to select the most suitable system for integration of electrodes within the eap pads (figure 1). the most feasible design system is shown, with one electrode as carbon mesh (1x1”) and the other as a pt wire as the point electrode. a silicone mold was poured such that the eap and electrodes fit in perfectly, with minimal excess casing. figure 1. different versions of eap based sensors. compression sensing characterization when mechanical pressure is applied to ras labs’ electroactive polymers, the change in resistance can be recorded. the eap resistance varies with applied pressure. this has been measured with several different variations of eaps and encapsulations, with each iteration becoming more consistent and reliable. the eaps, on average, have a relatively high resistance that varies slightly with pressure. the resistance was measured using an oscilloscope and reading the wheatstone bridge was attached to eap (figure 2). the circuit was attached to a 1v amplitude ac signal and the rms values recorded for each of a series of weight. this allows ras labs to use these polymers as resistive sensors in addition to their contractile properties for multiple applications. the sensing capabilities of these eaps are demonstrated using an oscilloscope and an analog multimeter (figure 3). figure 2. voltage rms vs mass for each of the version 2 eaps. figure 3. simple sensing demo using analog multimeter. flexy-hand 2 project the original files, from thingiverse, represented steve wood and jeff erenstone’s approach to making a hand for an ul amputee. we started with these open source files, edited them using computer-aided design (cad) software, and scaled down to the size of our petite patient’ hand, working with our customer’s anatomy of the vestige hand. a 3d scanner was used to get the patient’s mold scanned into the software, which was used to cut a better fit for the ‘socket’ of the partial hand (figure 4). by implementing the scan into the established flexy-hand 2, the goal was for a more comfortable and more stable fit for our patient during normal usage. figure 4. top left: the flexy-hand 2 (left) next to the modified flexy-hand 2 (right): top right: the modified flexyhand 2 (bottom) next to the ideal sized hand for this patient (top); bottom left: the upi-ras labs’ collaborative team constructing the modified hand; bottom right: the patient wearing the modified flexy hand 2. rasmussen l, rodriguez s, bowers m, smith d, martino g, rizzo l, scheiber c, d’almeida j, dillis c. adjustable liners and sockets for prosthetic devices. canadian prosthetics & orthotics journal, volume 1, issue 2, 2018; abstract, poster presentation at the aopa’s 101st national assembly, sept. 26-29, vancouver, canada, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.32048 3 open access aopa’s 101 st national assembly abstracts, september 26-29, vancouver, canada, 2018 abstract (poster presentation) conclusions and future work the modulation of the eap shape-morphing control as needed by controlling the voltage level were very promising. this technology is expected to provide for an adjustable prosthetic liner or socket that can maintain dynamic perfect fit throughout the day, for an advanced standard of care for amputees. ras labs is working with its collaborators (upi) and partners to gather evaluation and feedback from ak and bk amputees, with promising results. more patient testing is required over longer durations of use. ras labs’ synthetic muscle™ has the potential to sense pressure and provide for selfadjusting prosthetic liners, with no need for the patient to adjust the fit of their device. as sensors, variable voltage was observed when the eap sensor was mechanically compressed. moving towards pixilation of the sensing data will provide a wider range of data and feedback control. the goal is to give amputees natural locomotion with a worry-free prosthesis, maintaining dynamic perfect fit throughout the day and preventing tissue damage from even beginning to occur. with the flexyhand 2 modifications, we are advancing the design to fit any patient’s individual needs. next, we plan to add eap fingertip sensors to replicate touch while providing life-like compliancy and grip. acknowledge we gratefully acknowledge the national science foundation, breakout labs, children’s hospital of philadelphia/philadelphia pediatric medical device consortium, casis, us doe, and us dod for funding of the synthetic muscle projects. prosthetic applications are in collaboration with united prosthetics and additional partners. the mlsc internship challenge graciously provided intern support. references 1.rasmussen l et al. synthetic muscle electroactive polymer (eap) based actuation and sensing for prosthetic and robotic applications," proc. spie 10594, electroactive polymer actuators and devices (eapad) xx, 105942c. doi: 10.1117/12.2297660, 2018. 2.rasmussen l, editor, “electroactivity in polymeric materials,” springer-verlag, gmbh & co. kg © 2012. 3.rasmussen l, meixler l.d, gentile c. contractile electroactive materials and actuators. spie eapad 2012, proc. spie 8340, 1o:1-14, 2012. 4.rasmussen l et al. considerations for contractile electroactive polymer based materials and actuators. proc. spie 7976, 2b1-2b13, 2011. 5.wood s, erenstone j, flexy-hand 2, ttps://www.thingiverse. com/thing:380665 © 2018 6.sanders je, fatone s. residual limb volume change: systematic review of measurement and management. j rehabil res dev, 48(8): 949-986, 2011. doi:10.1682/jrrd.2010.09.0189 7.rasmussen l, et al. considerations for contractile electroactive polymeric materials and actuators. polym. int. 59: 290-299, 2010. https://doi.org/10.1002/pi.2763 8.zachariah sg et al. shape and volume change in the transtibal residuum over the short term. j rehabil rev dev, 41(5): 683-694, 2004. doi: 10.1682/jrrd.2003.10.0153 https://doi.org/10.1002/pi.2763 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 1 2020 balkaya i, altschuler e.l. correcting sherrington’s gait dysfunction with an off the shelf knee orthotic. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.4. https://doi.org/10.33137/cpoj.v3i1.34528 professional opinion # # there is no peer review process for professional opinion articles. http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://doi.org/10.33137/cpoj.v3i1.34528 1 balkaya i, altschuler e.l. correcting sherrington’s gait dysfunction with an off the shelf knee orthotic. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.4. https://doi.org/10.33137/cpoj.v3i1.34528 professional opinion correcting sherrington’s gait dysfunction with an off the shelf knee orthotic ihsan balkaya, eric l altschuler* department of physical medicine and rehabilitation, metropolitan hospital, new york, ny, usa. orthotics have been used to correct genu recurvatum in patients with hemiparesis following stroke1, 2 but have not typically been used to correct a pure proprioception deficit. in our physical medicine and rehabilitation (pm&r) prosthetics and orthotics clinic, we have found that off the shelf orthotics can be beneficial in treating gait dysfunction secondary to sensory deficits. this professional opinion describes, with supporting videos, a case where an off the shelf knee orthotic corrected the gait and function of a patient with hemisensory loss including proprioception following a stroke. interestingly, this case corrects a human analogue of a functional deficit found experimentally in monkeys in the 19th century by mott and sherrington.3 mott and sherrington showed that a purely sensory lesion in monkeys—sectioning the dorsal root ganglia—caused profound gait dysfunction.3 analogously, we saw a patient with a history of left thalamic stroke who presented with the inability to walk more than five minutes before stopping. he had normal strength (5/5) in the right leg, but absent light touch and proprioception (all joints) and his gait demonstrated significant recurvatum (video 1). a sports knee brace set in fixed 10 degrees of flexion not only prevented recurvatum, but also immediately normalized the gait (video 2). the patient can now walk more than a mile without stopping, and his quality of life has returned to what it was before the stroke. video 1 :severe right knee recurvatum and gait dysfunction without the brace. video 2: no recurvatum and a normal gait with brace on. it is of interest to note that when the patient in this case tried taking even a single step with the brace on, but his eyes closed, he immediately started to fall. however, when walking with his eyes open and wearing the brace, he did not need to watch his leg, instead simply had to look ahead to where he was going and was able to walk. this indicates that visual feedback on his position and the direction he intended to walk is likely integral to his motor ability to ambulate in the absence of proprioception. we have been pleased to find that we can provide significant clinical benefit to persons with mott and sherrington’s gait dysfunction using a simple, inexpensive, off the shelf knee orthotic and believe this approach has the potential to be implemented worldwide. declaration of conflicting interests the authors have no financial or other conflicts. the patient gave written informed consent for use of the videos. references 1.portnoy s, frechtel a, raveh e, schwartz i. prevention of genu recurvatum in poststroke patients using a hinged soft knee orthosis. pm r. 2015;7(10):1042-1051. doi:10.1016/ j.pmrj.2015.04.007 open access volume 3, issue 1, article no.4. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract this professional opinion describes the use of an off the shelf knee orthotic to correct the gait and functional mobility of a patient with hemisensory loss including proprioception following a stroke and provides supporting video. interestingly, this case corrects a human analogue of a functional deficit found experimentally in monkeys in the 19th century by mott and sherrington. *corresponding author eric l altschuler, md, phd metropolitan hospital 1901 first avenue, new york, ny, 10029, usa. e-mail: altschue@nychhc.org phone: (212) 423-6448 fax: (212) 423-6326 orcid: https://orcid.org/0000-0002-3575-6954 article info received: june 25, 2020 published: july 15, 2020 citation balkaya i, altschuler e.l. correcting sherrington’s gait dysfunction with an off the shelf knee orthotic. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.4. https://doi.org/10.33137/cpoj.v3i1.3 4528 keywords genu recurvatum, proprioception, knee orthotic, sherrington. https://doi.org/10.33137/cpoj.v3i1.34528 https://online-publication.com/wp/wp-content/uploads/2020/07/video-1-cpoj.mov https://online-publication.com/wp/wp-content/uploads/2020/07/video-2-cpoj.mov https://online-publication.com/wp/wp-content/uploads/2020/07/video-1-cpoj.mov https://online-publication.com/wp/wp-content/uploads/2020/07/video-1-cpoj.mov https://online-publication.com/wp/wp-content/uploads/2020/07/video-2-cpoj.mov https://jps.library.utoronto.ca/index.php/cpoj/index mailto:altschue@nychhc.org https://doi.org/10.33137/cpoj.v3i1.34528 https://doi.org/10.33137/cpoj.v3i1.34528 2 balkaya i, altschuler e.l. correcting sherrington’s gait dysfunction with an off the shelf knee orthotic. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.4. https://doi.org/10.33137/cpoj.v3i1.34528 issn: 2561-987x correcting sherrington’s gait dysfunction balkaya & altschuler, 2020 cpoj 2.appasamy m, de witt me, patel n, yeh n, bloom o, oreste a. treatment strategies for genu recurvatum in adult patients with hemiparesis: a case series. pm r. 2015 feb;7(2):105-12. doi: 10.1016/j.pmrj.2014.10.015 3.mott fw, sherrington cs. experiments on the influence of sensory nerves upon movement and nutrition of the limbs. proceedings of the royal society of london 1895; 57: 481–488. authors biography dr. ihsan balkaya is currently a pgy-3 pm&r resident at the new york medical college/metropolitan hospital program. after receiving his medical degree from istanbul university, he completed his internship at wayne state university in detroit, mi. a competitive handball player he is interested in sports medicine. eric altschuler, md, phd is associate chief of pm&r at metropolitan hospital in new york city and clinical associate professor at new york medical college. he is board certified in pm&r, brain injury medicine and neuromuscular medicine. the main focus of his research is clinically applied cognitive neuroscience. https://doi.org/10.33137/cpoj.v3i1.34528 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 2 2020 research article marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v3i2.34672 1 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 research article transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services marable w.r1, smith c1, sigurjónsson b.þ2, atlason i.f3, johannesson g.a2,4* 1 össur americas, foothill ranch, california, usa. 2 össur hf, reykjavik, iceland. 3 quick lookup, reykjavik, iceland. 4 teamolmed, stockholm, sweden. introduction transfemoral (tf) amputation(s) is a devastating procedure for any person and expensive in terms of acute healthcare cost1 and rehabilitation cost.2,3 tf amputation highly restricts the amputee’s overall mobility4 and requires a good functional prosthesis, especially the interface (i.e. the socket, the liner and its suspension) to enable the amputee to regain as much of their previous mobility as possible.5,6 tf amputation is also associated with longer amputee rehabilitation time compared with transtibial (tt) amputation and more need of assistance, especially in elderly patients.7 tf amputees report their general health related quality of life to be lower than that of non-amputees or tt amputees. furthermore, specific problems have been related to the use of tf prostheses, including limited hip joint range of motion that restricts users comfort or ability to perform daily activities such as sitting, walking, picking open access volume 3, issue 2, article no.6. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: direct socket for transfemoral (ds-tf) prosthetic user is a novel method of fabricating a laminated interface on to the residual limb but requires different training, production method and service model than what most prosthetists are familiar with. this method and model may improve patient satisfaction by enabling interface fabrication and delivery in one visit. objectives: document patient satisfaction regarding ds-tf interface versus the prosthetic users’ previous socket in terms of interface function and the clinic service model. methodology: in this longitudinal study (from july 2018 to april 2020), the ds-tf was implemented in six prosthetic clinics across the united states. certified prosthetists (cp) and assistants were trained using a standard protocol. 47 prosthetic users participated, both those in need of a new socket and those without need. two modules from the orthotics and prosthetics users’ survey (opus), involving questions related to satisfaction with the device and services, was used to evaluate each ds-tf user outcome vs. baseline. the only part of the prosthesis that was replaced was the interface, except in 2 cases. findings: each ds-tf interface was fabricated, fit and delivered in a single clinic visit. at 6-months follow-up, 38 users reported an average of 29.8% increase in satisfaction with their new interface compared with original, and a 14.8% increase in satisfaction with the services they received from the clinic in providing of the new prosthesis vs. their original prosthesis. the main outcome increases were between baseline (initial fitting) and 6-week follow-up and remained consistent after 6 months. this improvement was consistent irrespective if the user needed a new socket for clinical reasons or not. conclusion: this study shows that after a standardized training and implementation, the ds-tf fabrication process including a new interface, improves the user’s satisfaction with their prosthetic device and services. article info received: august 3, 2020 accepted: november 16, 2020 published: november 23, 2020 citation marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i 2.34672 keywords transfemoral amputation, amputee, prosthesis, socket, interface, outcome measure, satisfaction, direct casting * corresponding author: g. anton johannesson, phd teamolmed, kistagången 12, 164 40 kista, stockholm, sweden. e-mail: ajohannesson@teamolmed.se orcid: https://orcid.org/0000-0001-8729-458x https://doi.org/10.33137/cpoj.v3i2.34672 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i2.34672 https://doi.org/10.33137/cpoj.v3i2.34672 mailto:ajohannesson@teamolmed.se https://orcid.org/0000-0001-8729-458x 2 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj objects up from the floor, and tying their shoes.8,9 despite new materials and technology, the most frequently reported problem with the usage of tf prosthesis is still sores/skin irritation from the interface.10,11 prosthetic fitting of tf amputees has always been a challenging and time-consuming procedure that requires the user (and often family member or care giver) to make on average 4 visits to a prosthetic clinic.12 between 6 and 16 weeks pass from amputation to delivery of a tt or tf prostheses in high-income countries.13–15 fabricating a definitive tf interface has been reported to take at least 14 days using a traditional laminated interface process of casting, check socket(s) and laminated definitive interface.16 reducing the number of days in rehabilitation can reduce amputee rehabilitation costs by up to 25%.2 it has also been demonstrated that in patients amputated due to vascular reasons, functional mobility level declines as the number of days between amputation and start of rehabilitation increases. in the same study shorter time to prosthetic fitting was demonstrated to lead to improved functional outcomes six months after amputation.17 although many interesting new socket designs have been introduced to the market in the last 50 years, few studies have documented long term outcomes and/or quantitative data of a specific socket design.11 most published studies focus on tf amputee gait, socket design, suspension and/or function of the components including less than 15 amputees.8,18–20 kahle et al found that different socket designs may have an effect on gait speed and risk of falling.8 fatone et al., have described a new interface and the fabrication methods used to produce a tf socket, including outcomes from two cases.21,22 kahle et al., investigated the trimline level and compared outcomes between socket designs in 15 cases, although only in a clinical setting.18 the socket designs in these studies are mainly grounded on the prosthetist’s experience, with few measurable design parameters or description of how the design is intended to affect and interact with the user’s residual limb during the gait cycle.11 various terms have been proposed to describe the way forces are transferred between the residuum and the socket, the biomechanical principles upon which these terms are based are ill-defined.23 most recognized are terms used to describe the axial and transversal stabilization, e.g. ischial containment or inter ramus containment sockets.11 contact between this part of the hip bone (ischium and ramus inferior) and the socket can only be obtained during stance phase, which is approximately 0.6 sec of a full 1.07 sec gait cycle.24 during the rest of the gait cycle the ramus is moving in and out of the socket with little or no socket interaction. the position and effect of the “ischial-ramus containment” has not been revealed in studies except in theory.25 when this support or function is presumed to be lacking the term ”sub-ischial socket” has been used.26 the problem with this “definition” is that a transtibial or toe prosthesis could also be referred to as sub-ischial socket. this lack of detail and consistency in definitions prevents objective comparison.27 in an effort to provide detail and resolve the inconsistency, iso standard 13405-2:2015 contains recommendations on how to systematically describe an interface and provides a base for comparison between different interface design and function.23 a method of fabricating a finished laminated tt interface directly on the patient’s residual limb has been on the market since 1996. first introduced as icex by össur hf of iceland, icex was based on the inventor’s philosophy of pressure casting28 and was included in a variety of studies related to user satisfaction, cost and function.29–32 since then icex was improved to modular socket system (mss) in 2005,31 and finally to direct socket in 2018.33 this system enables a prosthetist to fabricate a custom-made interface directly on the tt residual limb in a single visit. the lesson learned from the use of ds-tt in scandinavia for over two decades and the finding related to the process, e.g. shorter rehabilitation time, demanded a solution for tf level.13 a tf version of direct socket (ds-tf) began testing in 2016 in select scandinavian clinics.30,31 the proximal portion of a ds-tf interface design differs significantly from the proximal portion of sockets typically called ischial containment or inter ramus containment sockets, as the proximal part of the ds-tf includes a size-specific silicone brim. the method of fabricating directly on the residual limb requires a different approach to prosthetist training and fabrication compared to the socket fabrication process most prosthetists apply today.33 the primary aim of this study was to collect data on prosthetic users satisfaction regarding ds-tf interface in terms of both interface function and the clinic service model (i.e. one patient visit to the clinic for fabrication of custom tf interface, prosthesis assembly, alignment, gait analysis, and delivery). list of abbreviations • cp: certified prosthetist • csd: client satisfaction with device • css: client satisfaction with services • ds-tf: direct socket for transfemoral • ds-tt: direct socket for transtibial • iso: international organization for standardization • iso/tc: 168 prosthetic and orthotics working group within iso • ispo: international society for prosthetics and orthotics • opus: orthotics and prosthetics user’s survey • o&p: orthotics and prosthetic • tf: transfemoral • tt: transtibial • 6wfu: six-weeks follow-up • 6mfu: six-month follow-up https://doi.org/10.33137/cpoj.v3i2.34672 3 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj methodology in this study, a new direct casting procedure for tf amputees called direct socket tf (ds-tf),34 was implemented in six different prosthetic clinics across the united states. the product includes all materials and tools to make a definitive socket. in the ds-tf fabrication process, a special 2.5mm casting liner is rolled onto the residual limb followed by a protective silicone sheath over the casting liner to prevent the resin from contacting the residual limb. next, a size-specific silicone brim is placed at the proximal part of the limb. a glass or basalt fabric with pre-attached distal adapter is then rolled on the length of the limb. a second protective sheath is applied on the outside of the fabric and a two-part resin is injected through the distal adapter (figure 1, figure 2) to approximately ½ to ¾ of the fabric length. the resin is absorbed through the fiber and kept isolated from the amputee by the two silicone sheaths on each side of the fabric. over the next 10-15 minutes the resin undergoes an exothermic reaction as it hardens, during which the cp can mold and shape the socket wall around the residual limb muscles that are relaxed or contracted as directed by the cp. the amputee can feel the warming socket, but socket temperature does not exceed 37.5 degree celsius, a typical adult body temperature. ds-tf interface description according to iso 13405-2:2015 section 5, (5.1.2.1 general) the force-transmission properties of ds-tf can be described, as follows: • (5.1.2.2) axial stabilization: the direct socket shape conforms to the shape of the femur, and soft tissues about the femur, causing even compression of the soft tissue, which creates axial stabilization (see also 5.1.3). • (5.1.2.3) transverse stabilization: even tissue compression created during the direct lamination process increases soft tissue density, creating anteroposterior, mediolateral, and rotational stabilization (see also 5.1.3). • (5.1.2.4) suspension: to minimize the axial movement, several suspension methods may be used; preferably a seal-in liner which creates partial distal vacuum, a locking liner with lanyard or pin can also be used. • (5.1.3) stiffness: the socket is laminated with a distal 4-hole adapter and a proximal brim made of flexible silicone. this makes the socket flexible proximally while most of the socket is rigid. the flexible circumference silicone brim encompasses and compresses the proximal thigh muscles when contracted, thereby stabilizing the hip at initial contact, loading response, mid-stance, and terminal-stance, and creating axial and transverse stabilization. during the rest of the gait (pre-, initial-, mid-, and late swing) the brim is only following the hip movement. the selection criteria for study principle investigators included a certified prosthetist (cp) with more than 5-years clinical experience in serving tf amputees with interest in improving patient outcomes and satisfaction, willingness to follow a defined novel fabrication protocol, and commitment to document outcome measures at defined time intervals. the inclusion criteria (rationale) is listed in table 1. figure 1: direct socket table 1: amputee inclusion criteria (rationale) amputee inclusion criteria (rationale) • 50kg< body weight < 160kg (the iso validated weight limit of the ds-tf) • cognitive ability to understand all instructions and questionnaires in the study • patients who have undergone a tf amputation > 1-year post amputation (this was to avoid postoperative problems and/or adjustments related the initial prosthetic fitting of a new amputee) • older than 18 years • willing and able to participate in the study and follow the protocol • circular dimension of 40-65 cm at the crotch (limited to available silicone brim sizes) • residual limb length at least 20 cm from ischium to distal end (fabrication limitation of the ds-tf) • currently using a prosthetic liner (this was to avoid potential confounding influence from transitioning an amputee from a skin fitting interface (i.e. without a liner), to an interface with a liner) • willing to use a silicone prosthetic liner as called for in direct socket instructions for use.34 silicone brim socket valve https://doi.org/10.33137/cpoj.v3i2.34672 4 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj training protocol direct socket fabrication was performed by a two-person team consisting of a lead and an assistant (figure 2). the lead was typically a cp while the assistant was commonly a prosthetic tech or certified prosthetic assistant. cp’s and assistants were trained in each cp’s clinic by certified clinical specialists using a standard protocol. prior to starting training and fabrication, demographic/clinical information and measurements were documented to ensure subjects were within the clinical limitations of the study. also, all necessary materials (sized for the scheduled amputees) were on hand, including direct socket toolkit, direct socket material kits, direct socket casting liners and direct socket fabrication manual. all training and fabrication were completed following the step-by-step process of the direct socket fabrication manual.34 amputees selected for clinician training were relatively uncomplicated without invaginations, unusual limb shapes or extreme alignments. after training, the clinical training figure 2: ds-tf process a) application of material, b) resin injection, c) moulding of resin, d) first fit and alignment check. a b c d https://doi.org/10.33137/cpoj.v3i2.34672 5 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj specialist remained available to remotely consult with trainee cp’s as needed. follow up and data collection including the baseline, three time periods were used to assess outcomes (figure 3). after 6 weeks subjects returned to the clinic and completed the same standardized surveys regarding their new prosthesis (6wfu). subjects returned to the clinic again and completed the same surveys after 6 months as well (6mfu). prior to the fitting each amputee subject was asked to fill out a standardized survey regarding their existing prosthesis and the experience of the service that they previously received. after baseline the cp and assistant fabricated and delivered a new ds-tf interface and liners. for the evaluations the orthotics and prosthetics user’s survey (opus) was used. the opus is a set of selfreported outcome measures to be used within o&p clinics for the assessment of functional status, quality of life, and client satisfaction.35 the opus was originally developed in english and has been translated into multiple languages, including spanish, swedish and slovenian. the opus has displayed good internal consistency and has been validated in us and swedish populations.36 the opus instrument consists of five independent modules, two of which were used in this study: client satisfaction with device (csd) and client satisfaction with services (css). the csd and css include a total of 21 questions, scored on a 1 6, discrete scale: strongly agree, agree, neither agree nor disagree, disagree, strongly disagree and don´t know/not applicable. the opus can be used on prosthesis and/or orthosis users. however, since this study was exclusively on prosthesis users, to prevent confusion the words “orthosis” and “orthotist” used in the original survey text were not included in this study’s user surveys. the csd score is the sum of scores for items 1-11 (11 – 55 points) and relates to the function of the device and the user’s cost to acquire the device. meanwhile the css score is the sum of the scores for items 12-21 (10 – 50 points) and relates to the service the amputee received. a higher score indicates a better outcome. these raw scores were then converted to rasch measure (0 – 100 scale) and measure of variability is reported with the mean.36 the “device” that is referred to in the questionnaire includes the complete prosthesis, of which questions 1, 3, 4, 8 and 9 only pertain to the interface. the ds-tf was delivered without any additional finishing components at baseline. this study uses the k-scale system established in 1995, also called medicare functional classification levels (mfcl). the k levels divide lower limb amputees into five categories ranging from k level 0 (least mobile) to k level 4 (most mobile) intended to indicate a person’s rehabilitation potential.37 sample size calculation and statistical methods a pretrial power analysis for the estimated required sample size was conducted using gpower38 version 3.1.9.6 and effect size was estimated based on published articles9,39,40 for the primary endpoint assuming a normally distributed amputee population. it was therefore expected that 38 subjects were required to complete the protocol with a power of 0,95 and α at 0,05. drop-out rate was estimated at proximally 20% and therefore 47 subjects were recruited. we used r version 4.03 (r-studio version 1.2.5033) and lme441 to perform a linear mixed effects analysis of the relationship between the opus outcomes and clinical need. as fixed effects, we entered age, gender, and evaluation point (tested for interaction with “clinical need”) into the model. as random effects, we had intercepts for subjects and investigators, as well as by-subject and by-item random slopes for the effect of clinical need. p-values were obtained by likelihood ratio tests of the full model with the effect in question against the model without the effect in question. for comparison of individual opus items, the benjamini & hochberg method was used to control for type i error due to multiple comparisons.42 results between july 2018 and october 2019, 47 tf prosthetic users that fulfilled the eligibility criteria and agreed to participate in the study were enrolled. ethical approval was obtained from advarra® irb (cr00128417) and the investigation was registered at clinical trials.gov nct04312724. signed informed consent was obtained from all participants. study subjects, included for data collection and analysis, consisted of prosthetic users fitted during the training of each cp on ds-tf fabrication, as well as users fitted by cp’s post training. the study group consisted of both users who needed a replacement prosthetic interface, according to new referral, due to wear and tear or volume changes (n=28; 26 analyzed; “clinical need”), and those with no clinical need of replacement (n=10) (table 2). study investigators indicate their criteria to determine if a new interface was clinically justified included: volume reduction requiring 5-7 sock ply or more (>7% volume reduction),43 socket discomfort, socket instability or significant skin irritation. the mean age of subjects was 59 years (36-79 years) and represented wide range of activity levels. study subjects exhibited baseline activity levels from k-level 1 to k-level 4, (k-level 1, n=4; k-level 2, n=11; k-level 3, n=21; and finally k-level 4, n=11). https://doi.org/10.33137/cpoj.v3i2.34672 6 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj data was collected and analysed for 47 subjects at baseline. at 6wfu the results from 40 subjects were included and 6mfu included results from 38 subjects (figure 3), providing a power of 95.3% and 95.2% for the follow-ups, respectively. two subjects, from the group “with clinical need for new interface” did not complete the opus instrument at all three measurement time periods and are therefore not included in the data analysis for 6mfu. all prosthetic users included in the study used a liner with their interface. thirty-three of them used seal-in liners, 5 used locking liners, 5 used lanyard and the rest used various types of liners and suspensions. the most frequent liner size was 35cm (range 25-50cm). while 36 of the users used microprocessor-controlled prosthetic knees from 2 different manufacturers, 11 knees were nonmicroprocessor-controlled prosthetic knees from 3 different manufacturers. subjects’ prosthetic feet included extensive functional variation depending on user k-level, from a sach foot to high activity feet, made by 4 different manufacturers. all subjects retained their existing knee and/or foot, except for two subjects that received a new knee and foot with the new interface. nine of the subjects dropped out of the study, 7 of them before 6wfu (including one deceased) and 2 of them before 6mfu (figure 3). one subject who had advanced vascular disease and a very small limb decided to withdraw from the study after one week. three subjects withdrew from study, preferring their previous socket. one subject had shoulder surgery and was non-ambulatory for a significant part of the study for reasons not having to do with the prosthesis. since the subject did not fulfil all steps of the study, he was considered a drop-out, however, the subject was still using the new interface when the study ended. three subjects did not respond to follow-up. at least two of them continue to use the new ds-tf interface. figure 3: flow chart of the investigation drop out before six-weeks: • 1 subject died • 4 subject went back to their previous interface • 1 due to sever vascular problems (not device related) • 3 due to poor m-l stability (compared with existing interface) • 2 lost to follow-up (one still using the new interface) at six-months follow-up (6mfu) (n =38) (n = 38; 36 analysed as 2 subjects were missing full opus data sets) evaluations measurement used: • opus (21 items) at six-weeks follow-up (6wfu) (n = 40) evaluations measurement used: • opus (21 items) all subject that was enrolled into the study at 6 different prosthetic clinics (baseline) (n = 47) evaluations measurement used: • opus (21 items) drop out at six-month: • 1 subject went for additional surgery on the contralateral side (still uses the new interface) • 1 lost from follow-up (still using the new interface) https://doi.org/10.33137/cpoj.v3i2.34672 7 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj table 2: characteristics of the study population stratified into follow-up periods according to those prosthetic users in need or not in need of a new interface. baseline 6wfu 6mfu n 47 40 38 men/women 33/14 29/11 28/10 age (sd) in years 58.9 (11.8) 58.3 (11.7) 58.0 (12.0) subjects in need of new interface 34 29 28 (-2)** age (sd) in years) 59.0 (11.8) 58.2 (11.8) 58.1 (12.2) average k-level* 2.7 (0.9) 3.0 (0.8) 3.0 (0.9) subjects not in need of new interface 13 11 10 age (sd) in years 58.8 (12.3) 58.5 (11.9) 57.9 (12.5) average k-level* 3.0 (0.8) 3.3 (01.0) 3.3 (0.8) age is referred to as means + sd * k-level 1, k-level 2, k-level 3, k-level 4 ** two subject did not complete all measurement at all three time periods table 3: a: opus client satisfaction device (csd) (questions 1-11). b: opus client satisfaction with services (css) (questions 12-21) a baseline 6wfu 6mfu all subjects (n=47) (n=41) (n=36) p 1. my prosthesis fits well… 3.0 (1.2)* 4.3 (1.0) 4.6 (0.9) <.001 2. the weight of my prosthesis is manageable… 3.8 (1.1) 4.5 (0.8) 4.5 (0.8) <.001 3. my prosthesis is comfortable throughout the day… 3.0 (1.3) 4.0 (1.2) 4.4 (0.9) <.001 4. it is easy to put on my prosthesis... 3.7 (1.1) 4.4 (0.9) 4.6 (0.6) <.001 5. my prosthesis looks good… 3.8 (1.1) 4.2 (0.9) 4.7 (0.6) <.001 6. my prosthesis is durable… 4.0 (1.1) 4.4 (0.9) 4.7 (0.5) <.001 7. my clothes are free of wear and tear from my prosthesis... 3.3 (1.4) 4.1 (1.0) 4.1 (1.1) <.001 8. my skin is free of abrasions and irritations… 3.1 (1.4) 4.0 (1.1) 4.0 (1.1) <.001 9. my prosthesis is pain free to wear… 2.8 (1.3) 3.7 (1.0) 4.1 (1.2) <.001 10. i can afford the out-of-pocket expenses to purchase and maintain my prosthesis 2.6 (1.4) 3.3 (1.5 2.7 (1.5) 0.91 11. i can afford to repair or replace my prosthesis as soon as needed 2.5 (1.5) 3.1 (1.6) 2.6 (1.5) 0.91 b 12. i received an appointment with a prosthetist within a reasonable amount of time… 4.6 (0.7) 4.8 (0.4) 4.9 (0.4) 0.03 i was shown the proper level of courtesy and respect by the staff… 4.8 (0.4) 4.9 (0.5) 5.0 (0.2) 0.25 14. i waited a reasonable amount of time to be seen… 4.6 (0.9) 4.9 (0.4) 4.9 (0.3) 0.03 15. clinic staff fully informed me about equipment choices… 4.6 (0.7) 4.9 (0.3) 4.9 (0.2) 0.03 16. the prosthetist gave me the opportunity to express my concerns regarding my equipment… 4.8 (0.5) 4.9 (0.3) 4.9 (0.3) 0.15 17. the prosthetist was responsive to my concerns and questions.... 4.8 (0.4) 5.0 (0.2) 4.9 (0.3) 0.25 18. i am satisfied with the training i received in the use and maintenance of my prosthesis… 4.7 (0.5) 5.0 (0.2) 4.7 (0.9) 0.95 19. the prosthetist discussed problems i might encounter with my equipment… 4.7 (0.5) 5.0 (0.0) 4.9 (0.4) 0.13 20. the staff coordinated their services with my therapists and doctors… 4.5 (0.8) 4.4 (1.3) 4.9 (0.3) 0.15 21. i was a partner in decision-making with clinic staff regarding my care and equipment… 4.7 (0.5) 4.9 (0.3) 4.9 (0.3) 0.08 *all data are presented as mean (sd) https://doi.org/10.33137/cpoj.v3i2.34672 8 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj each ds-tf interface was fabricated, fit and delivered in a single clinic visit. 36% of subjects surveyed at 6wfu had required minor adjustments by the study cp to the ds-tf between initial fitting and the 6wfu. satisfaction assessment of all participants (table 3 a,b) average csd scores (the sum of questions 1-11 on a 100point rasch measure scale) for participants that completed the 6mfu (n=36) were: • 46.9 (sd=9.8) at baseline (i.e. existing interface/prosthesis) • 60.6 (sd=14.5) at 6wfu, an increase of 29.8 (sd=3.3)% compared to baseline with p<.001 • 61.0 (sd=14.0) at 6mfu, an increase of 29.8 (sd=3.3)%, compared to baseline, with p<.001 each question directly related to the use of the new interface (items 1-9), showed significant improvement in outcome, with the main difference between baseline and 6wfu. improvement was sustained in all 9 questions between 6wfu and 6mfu (table 3 a for individual scores; f statistic = 29.1 degrees of freedom = 5). no study subject responded to any survey question with the selection "don´t know / not applicable". mixed effect model analysis showed that “clinical need” did not affect the csd measure (chi squared = 0.27, p = 0.60). average css scores (the sum of questions 12-21 on a 100 point rasch measure scale) for participants that completed the 6mfu (n=36) were: • 81.3 (sd=19.9) at baseline • 90.6 (sd=14.1) at 6wfu, an increase of 12.3 (sd=2.2)% compared to baseline with p=0.009 • 93.1 (sd=13.8) at 6mfu, an increase of 14.8 (sd=2.2)% compared to baseline with p=0.001 see table 3b for individual scores; f statistic = 8.2; degrees of freedom = 5). mixed effect model analysis showed that “clinical need” did not affect the css measure (chi squared = 0.04, p=0.85). satisfaction assessment of participants with the clinical need for new interface (table 4 a,b) for participants that completed the 6mfu (n=26) average csd scores were: • 45.5 (sd=9.1) at baseline • 60.5 (sd=14.0) at 6wfu, an increase of 33.3 (sd=3.9) % with p<.001 • 61.9 (sd=14.1) at 6mfu, an increase of 37.8 (sd=4.0) %, compared to baseline with p<.001 average css scores were: • 80.8 (sd=20.2) at baseline • 91.0 (sd=15.2) at 6wfu, an increase of 12.3 (sd=3.4) % with p=0.055 • 93.3 (sd=13.4) at 6mfu, an increase of 14.8 (sd=3.4)% compared to baseline with p<.005. satisfaction assessment of participants without the clinical need for new interface (table 5 a,b) for participants that completed the 6mfu (n=10) average csd scores were: • 50.7 (sd=11.1) at baseline • 61 (sd=16.4) at 6wfu, an increase of 19.6 (sd=4.5)% with p=0.018 • 58.7 (sd=14.0) at 6mfu, an increase of 15.6 (sd=4.9) % compared to baseline with p=0.047 average css scores were: • 82.8 (sd=20.0) at baseline • 89.5 (sd=11.6) at 6wfu, an increase of 8.8 (sd=7.5)% compared to baseline with p=0.195 • 92.6 (sd=15.5), at 6mfu, an increase of 12.0 (sd=7.9)% compared to baseline with p= 0.103. discussion opus csd questions related to the function of the interface for all subjects indicate a significant improvement in user satisfaction with their ds-tf interface over their previous interface in terms of weight, comfort, donning, appearance, durability, and reduced clothing wear and tear. results also showed significantly improved satisfaction regarding skin abrasions and irritation, as well “pain free to wear”. all improvements were consistent between the 6-week and 6month study periods. at 6mfu the average css score was 93, or 14.8% higher, a significant improvement compared with baseline. one might think that amputees who need a new socket for clinical reasons may be more dissatisfied with their existing socket than amputees who do not need a new socket for clinical reasons, and might therefore be more inclined to show greater satisfaction improvement with a new prosthesis than the subjects who did not need a new interface. to identify this potential influence, all completed subject data was analyzed together, as well as broken into two separate cohorts“with clinical need of new interface” and “without clinical need of new interface”. analysis indicates that “clinical need” did not significantly affect the csd and css measures. https://doi.org/10.33137/cpoj.v3i2.34672 9 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj table 4: a: opus client satisfaction device (csd) (questions 1-11); b: opus client satisfaction with services (css) (questions 12-21). a baseline 6wfu 6mfu subject with clinical need (n=26) (n=26) (n=26) 1. my prosthesis fits well… 2.8 (1.2) 4.3 (0.8) 4.6 (1.0) 2. the weight of my prosthesis is manageable… 3.6 (1.2) 4.4 (0.9) 4.5 (0.9) 3. my prosthesis is comfortable throughout the day… 2.8 (1.4) 4.0 (1.1) 4.3 (1.0) 4. it is easy to put on my prosthesis... 3.6 (1.2) 4.4 (0.9) 4.7 (0.6) 5. my prosthesis looks good… 3.7 (1.1) 4.2 (1.1) 4.7 (0.5) 6. my prosthesis is durable… 3.8 (1.4) 4.3 (1.0) 4.7 (0.5) 7. my clothes are free of wear and tear from my prosthesis... 3.2 (1.4) 4.2 (1.0) 4.3 (0.9) 8. my skin is free of abrasions and irritations… 3.3 (1.4) 4.2 (0.8) 4.2 (1.0) 9. my prosthesis is pain free to wear… 2.6 (1.2) 3.8 (1.0) 4.2 (1.1) 10. i can afford the out-of-pocket expenses to purchase and maintain my prosthesis… 2.5 (1.4) 3.5 (1.5) 2.7 (1.5) 11. i can afford to repair or replace my prosthesis as soon as needed 2.5 (1.5) 3.3 (1.6) 2.5 (1.4) b 12. i received an appointment with a prosthetist within a reasonable amount of time… 4.7 (0.5) 4.8 (0.4) 4.9 (0.4) 13. i was shown the proper level of courtesy and respect by the staff… 4.8 (0.4) 4.8 (0.6) 5.0 (0.2) 14. i waited a reasonable amount of time to be seen… 4.6 (0.9) 4.8 (0.5) 4.9 (0.3) 15. clinic staff fully informed me about equipment choices… 4.6 (0.8) 4.9 (0.3) 4.9 (0.3) 16. the prosthetist gave me the opportunity to express my concerns regarding my equipment… 4.7 (0.5) 4.8 (0.4) 4.9 (0.3) 17. the prosthetist was responsive to my concerns and questions.... 4.8 (0.4) 5.0 (0.2) 4.9 (0.3) 18. i am satisfied with the training i received in the use and maintenance of my prosthesis… 4.7 (0.5) 5.0 (0.2) 4.9 (0.3) 19. the prosthetist discussed problems i might encounter with my equipment… 4.7 (0.5) 5.0 (0.0) 4.8 (0.5) 20. the staff coordinated their services with my therapists and doctors… 4.5 (0.9) 4.5 (1.4) 4.9 (0.3) 21. i was a partner in decision-making with clinic staff regarding my care and equipment… 4.6 (0.5) 4.9 (0.3) 4.9 (0.3) table 5: a: opus client satisfaction device (csd) (questions 1-11); b: opus client satisfaction with services (css) (questions 12-21). a baseline 6wfu 6mfu subject with no clinical need (n=10) (n=10) (n=10) 1. my prosthesis fits well… 3.6 (0.8) 4.7 (0.7) 4.5 (0.5) 2. the weight of my prosthesis is manageable… 4.5 (0.5) 4.9 (0.3) 4.6 (0.5) 3. my prosthesis is comfortable throughout the day… 3.5 (1.0) 4.5 (0.7) 4.4 (0.7) 4. it is easy to put on my prosthesis... 3.9 (0.7) 4.8 (0.4) 4.6 (0.7) 5. my prosthesis looks good… 4.0 (0.7) 4.5 (0.7) 4.6 (0.7) 6. my prosthesis is durable… 4.3 (0.7) 4.7 (0.7) 4.6 (0.7) 7. my clothes are free of wear and tear from my prosthesis... 3.5 (1.4) 4.3 (1.1) 3.7 (1.3) 8. my skin is free of abrasions and irritations… 3.0 (1.2) 3.6 (1.4) 3.6 (1.2) 9. my prosthesis is pain free to wear… 3.4 (1.3) 3.6 (1.1) 3.7 (1.3) 10. i can afford the out-of-pocket expenses to purchase and maintain my prosthesis… 2.7 (1.4) 2.6 (1.5) 2.8 (1.6) 11. i can afford to repair or replace my prosthesis as soon as needed 2.4 (1.4) 2.6 (1.6) 2.9 (1.7) b 12. i received an appointment with a prosthetist within a reasonable amount of time… 4.4 (1.0) 4.7 (0.5) 5.0 (0.0) 13. i was shown the proper level of courtesy and respect by the staff… 4.8 (0.4) 5.0 (0.0) 5.0 (0.0) 14. i waited a reasonable amount of time to be seen… 4.5 (1.0) 5.0 (0.0) 5.0 (0.0) 15. clinic staff fully informed me about equipment choices… 4.8 (0.4) 4.9 (0.3) 5.0 (0.0) 16. the prosthetist gave me the opportunity to express my concerns regarding my equipment… 4.8 (0.4) 5.0 (0.0) 5.0 (0.0) 17. the prosthetist was responsive to my concerns and questions.... 4.8 (0.4) 5.0 (0.0) 4.9 (0.3) 18. i am satisfied with the training i received in the use and maintenance of my prosthesis… 4.7 (0.5) 5.0 (0.0) 4.3 (1.7) 19. the prosthetist discussed problems i might encounter with my equipment… 4.7 (0.5) 5.0 (0.0) 5.0 (0.0) 20. the staff coordinated their services with my therapists and doctors… 4.6 (0.5) 4.4 (1.1) 5.0 (0.0) 21. i was a partner in decision-making with clinic staff regarding my care and equipment… 4.8 (0.4) 4.9 (0.3) 4.9 (0.3) all data are presented as mean (sd) https://doi.org/10.33137/cpoj.v3i2.34672 10 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj across both user groups average csd opus scores were significantly improved after fitting subjects with ds-tf interfaces. in all cases, the cp was able to fabricate, align, fit, adjust, and deliver the new interface in the same visit, with only 36% of subjects returning to the clinic for a postdelivery socket adjustment. to our knowledge this study is one of largest and longest prosthetic user satisfaction outcome studies published to date with focus on a new interface design. in this study we followed 38 tf amputees, comprised of household ambulators up to high active users (k1 to k4) for 6-months. our observed 19% drop-out rate (9 out of 47) can be expected in such a group over multiple data collection intervals and 6-months’ time.40 we believe the improved user satisfaction with service is from two factors that ds-tf enables: 1) single-visit fabrication and delivery, and 2) that subjects feel more “involved” in their socket fabrication. while it is possible that baseline opus scores may include subject recall bias since patients received their existing prosthesis and interfaces months or years in the past, we believe a comparison is informative. as the ds-tf fabrication and delivery can usually be completed in a single (but longer) clinic visit, ds-tf eliminates or reduces the hassle of multiple trips to the clinic by the amputee and family or care givers. during the current covid-19 pandemic, tf amputees may especially value fewer clinic visits in order to reduce their risk of infection. cp’s fabricate ds-tf sockets directly on the residual limb; anecdotal subject reports indicate users enjoyed the opportunity to be more involved in the entire process, to see each step, to communicate with their cp and be a part of design decisions (e.g. the position of the brim, how to manage sensitive areas, placement of the valve, etc.). in liquid form the two-part resin used in ds-tf fabrication can cause injury to amputee and clinicians if handled improperly. it is therefore critical to follow safe ds-tf fabrication procedures using protective equipment for clinicians and amputee which means process training and practice of ds-tf fabrication should never be underrated.34 the current standard of care for tf interface design focuses on the proximal aspect of the socket to achieve a stable stance-phase connection between socket and amputee. the proximal socket brim extends above the femur and is intended to contain the ischial ramus, thereby preventing a lateral shift of the socket and enhancing user stability.26 to deliver a finished laminated tf interface of this type most cp´s use a complicated multi-step fabrication process including: hand casting, one or more test sockets, one or more laminated sockets, and usually at least one post-fitting adjustment where patient comes back to the clinic. however, this socket design has never been described using the iso standard 13405-2:2015. this method is also dependent on many years of cp experience and rarely based on evidence and/or outcome studies. the direct casting method used in this study is a different concept and process, unlike most cp’s traditional processes. the ds-tf socket is a true transfemoral socket as no rigid part of the ds-tf socket bears load from the ischium bone. ds-tf instead focuses on a unique way of supporting the hip joint through the hip muscles; i.e. when the hip muscles contract and expand during stance phase, the ds-tf brim supports the hip muscles. the support that the ds-tf brim provides, activates and stimulates important hip muscle function44 to enable axial and transverse stability during normal walking.23 these different interfaces (their function and design) should follow standardized method when they are described, this to enhance baseline comparison.23 it should be noted that the cost of prosthetic provision has been shown to be less than 10% of the total cost of an amputation,45 with delayed rehabilitation adding considerable expense to the total cost.2 it has also been demonstrated that less time between amputation and weight bearing or ambulation therapy can both contribute to faster restoration of the walking ability after a lower limb amputation46 and reduce the cost of rehabilitation of these patients.2 using ds-tf a prosthetist can potentially reduce the time between amputation and start of weight bearing and physical therapy down to 6 weeks as shown in study when using the ds-tt.13 ds-tf can be an important tool to improve lower limb amputee outcomes and potentially reducing the overall health care costs to society of treating transfemoral amputees. limitations study subjects received their existing interfaces months or years in the past. therefore, having users complete the opus on their existing socket introduces the possibility of recall bias. primary study limitation is not having the amputees randomized into ds-tf (intervention) and control (traditional interface) groups. dividing the cohort into groups based on “clinical need” for a new interface versus no clinical need for a new interface was a partial mitigation of this limitation. however, the aim of this study was to evaluate the implementation of direct fabrication on the amputee’s limb and to gather subject outcomes over an extended and clinically meaningful time. new amputees often take an extended time to adjust to the interface, therefore we suggest that future studies would follow new users over one year, randomized into two groups of traditional interfaces versus ds-tf interfaces. several study subjects provided anecdotal reports of significantly reduced phantom pain, therefore another potential area of further research would be to investigate the impact of dstf on phantom pain. https://doi.org/10.33137/cpoj.v3i2.34672 11 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj conclusion this study shows that following a standardized training and implementation plan, the ds-tf process can be successfully applied in caring for tf prosthetic users. the unique ds-tf interface design yields greater user satisfaction regarding interface function and comfort compared to a traditional tf interface design. the novel ds-tf interface fabrication method also yields increased user satisfaction with the cps’ fabrication and delivery of the interface and prosthesis compared to the service users received along with their previous interface. acknowledgements we would like to acknowledge the cp´s who participated in the study; j. walker, r. camper, j. arnold, k. keeling, b. sampson, e. thompson, s. parkinson, c. smith, b. clark and all of the technicians involved. declaration of conflicting interests all authors are employees of össur hf except i. f. atlason. study principle investigators received no compensation from össur hf. author contribution • w. russ marable: conceptualization; study oversight; data collection; writing original; review and editing • christian smith: conceptualization; data collection; writing original; review and editing • benedikt þorri sigurjonsson: conceptualization; obtained funding; study oversight; data analysis; review and editing • ingi freyr atlason: data analysis • g. anton johannesson: conceptualization; study oversight; data analysis; writing original; review and editing sources of support this study was financially supported by össur hf. ethical approval ethical approval was obtained from advarra® irb (cr00128417) and the investigation was registered at clinical trials.gov nct04312724. signed informed consent was obtained from all participants. references 1.eneroth m, apelqvist j, troeng t, persson bm. operations, total hospital stay and costs of 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h. a survey of the lower limb amputee population in scotland 2015 public report [internet]. 2018; [cited 2020, nov 16]. available from: http://www.knowledge.scot.nhs.uk/media/clt/resourceuploads/4 093845/ed2d2db3-ca6a-442d-a324-10dcc431707d.pdf 17.sauter cn, pezzin le, dillingham tr. functional outcomes of persons who underwent dysvascular lower extremity amputations: effect of postacute rehabilitation setting. am j phys med rehabil. 2013;92(4):287–96. doi: 10.1097/phm.0b013e31827d620d 18.kahle j, miro rm, ho lt, porter m, lura dj, carey sl, et al. the effect of the transfemoral prosthetic socket interface designs on skeletal motion and socket comfort: a randomized clinical trial. prosthet orthot int. 2020; 44(3):145-154. doi: 10.1177/0309364620913459 19.traballesi m, delussu a, averna t, pellegrini r, paradisi f, brunelli s. energy cost of walking in transfemoral amputees: comparison between marlo anatomical socket and ischial containment socket. gait posture. 2011;34(2):270-274. doi:10.1016/j.gaitpost.2011.05.012 20.rutkowska-kucharska a, kowal m, winiarski s. relationship between asymmetry of gait and muscle torque in patients after unilateral transfemoral amputation. appl bionics biomech. 2018; doi: 10.1155/2018/5190816 21.fatone s, caldwell r. northwestern university flexible subischial vacuum socket for persons with transfemoral amputation-part 1 : description of technique. prosthet orthot int. 2017;41(3):237–245. doi: 10.1177/0309364616685229 22.fatone s, caldwell r. northwestern university flexible subischial vacuum socket for persons with transfemoral amputation: part 2: description and preliminary evaluation. prosthet orthot int. 2017;41(3):246–250. doi: 10.1177/0309364616685230 23.iso 13405-2:2015 prosthetics and orthotics-classification and description of prosthetic components part 2: description of lower limb prosthetic components [internet]. 2015; [cited 2020, nov 16]. available from: https://www.iso.org/standard/42290.html?browse=tc 24.murray mp, drought ab, kory rc. walking patterns of normal men. j bone joint surg am. 1964;64(2):335–360. 25.pritham ch. biomechanics and shape of the above-knee socket considered in light of the ischial containment concept. prosthet orthot int. 1990;14(1):9–21. doi:10.3109/03093649009080311 26.kahle jt, jason highsmith mj. transfemoral sockets with vacuum-assisted suspension comparison of hip kinematics, socket position, contact pressure, and preference: ischial containment versus brimless. j rehabil res dev. 2013;50(9):1241–52. doi: 10.1682/jrrd.2013.01.0003 27.ispo collaboration with the international organization for standardization [internet]. 2020; [cited 2020, nov 16]. available from: https://www.ispoint.org/general/custom.asp?page=iso 28.kristinsson. the iceross concept: a discussion of a philosophy. prosthet orthot int. 1993;17(1):49–55. doi: 10.3109/03093649309164354 29.selles rw, janssens pj, jongenengel cd bj. a randomized controlled trial comparing functional outcome and cost efficiency of a total surface-bearing socket versus a conventional patellar tendon-bearing socket in transtibial amputees. arch phys med rehabil. 2005;86(1):154–180. doi: 10.1016/j.apmr.2004.03.036 30.johannesson a, larsson gu, öberg t. from major amputation to prosthetic outcome: a prospective study of 190 patients in a defined population. prosthet orthot int. 2004;28(1). doi: 10.3109/03093640409167920 31.normann e, olsson a, brodtkorb t-h. modular socket system versus traditionally laminated socket: a cost analysis. prosthet orthot int. 2011;35(1):76–80. doi: 10.1177/0309364610392812 32.larsson b, johannesson a, andersson ih, atroshi i. the locomotor capabilities index; validity and reliability of the swedish version in adults with lower limb amputation. health qual life outcomes. 2009;7. doi: 10.1186/1477-7525-7-44 33.össur-academy. direct socket system by össur hf, reykjavik, iceland. [internet]. 2020; [cited 2020, nov 16]. available from: https://www.youtube.com/watch?v=okljzjkqg3m&t=4s 34.össur hf, reykjavik i. direct socket tf [internet]. 2020-10-12. 2020; [cited 2020, nov 16]. available from: https://www.ossur.com/en-us/prosthetics/sockets/direct-socket-tf 35.heinemann a. development and measurement properties of the orthotics and prosthetics users’ survey (opus): a comprehensive set of clinical outcome instruments. prosthet orthot int. 2003;27(3.):191-206. doi: 10.1080/03093640308726682 36.jarl gm, heinemann aw, hermansson lm. validity evidence for a modified version of the orthotics and prosthetics users’ survey. disabil rehabil assist technol. 2012;7(6):469–478. doi: 10.3109/17483107.2012.667196 37.balk e, gazula a, markozannes g. lower limb prostheses: measurement instruments, comparison of component effects by subgroups, and long-term outcomes [internet]. 2018; [cited 2020, nov 16]. available from: https://www.ncbi. nlm.nih.gov/books/nbk531517/table/ch2.tab1 38.gpower [internet]. 3.1.9.2. [cited 2020, nov 16]. available from: https://www.psychologie.hhu.de/arbeitsgruppen/allgemeinepsychologie-und-arbeitspsychologie/gpower.html 39.johannesson a, larsson g-u, ramstrand n, turkiewicz a, wiréhn a-b, atroshi i. incidence of lower-limb amputation in the diabetic and nondiabetic general population: a 10-year populationbased cohort study of initial unilateral and contralateral amputations and reamputations. diabetes care. 2009;32(2). doi: 10.2337/dc08-1639 40.pohjolainen t, alaranta h, kärkäinen m. prosthetic use and functional and social outcome following major lower limb amputation. prosthet orthot int. 1990;14(2):75–79. doi: 10.3109/03093649009080326 41.bates k, bolker b, walker s, christiensen rh, singmann h, dai b, et al. ime4 [internet]. package ´lme4´. 2020; [cited 2020, nov 16]. available from: https://github.com/lme4/lme4/ https://doi.org/10.33137/cpoj.v3i2.34672 13 marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.6. https://doi.org/10.33137/cpoj.v3i2.34672 issn: 2561-987x transfemoral socket fabrication method using direct casting marable et al. 2020 cpoj 42.benjamini y, hochberg y. controlling the false discovery rate: a practical and powerful approach to multiple testing. j r stat soc series b stat methodol. 1995;57(1):289-300. doi: 10.1111/j.25176161.1995.tb02031.x 43.sanders je, cagle jc, harrison ds, karchin a. amputee socks: how does sock ply relate to sock thickness? prosthet orthot int. 2012;36(1):77–86. doi: 10.1177/0309364611431290 44.raya ma, gailey rs, fiebert im, roach ke. impairment variables predicting activity limitation in individuals with lower limb amputation. prosthet orthot int. 2010;34(1):73–84. doi: 10.3109/03093640903585008 45.hermodsson y, ekdahl c, persson bm. outcome after trans‐ tibial amputation for vascular disease: a follow‐up after eight years. 2008;1–14. doi:10.1111/j.1471-6712.1998.tb00479.x 46.highsmith m, kahle j, miro r, orendurff m, lewandowski a, orriola j, et al. prosthetic interventions for people with transtibial amputation: systematic review and meta-analysis of high-quality prospective literature and systematic reviews. j rehabil res dev. 2016;53(2):157-84. doi: 10.1682/jrrd.2015.03.0046. https://doi.org/10.33137/cpoj.v3i2.34672 campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30843 research article issn: 2561-987x all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x volume 1, issue 2 2 0 1 8 https://doi.org/10.33137/cpoj.v1i2.30843 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30843 1 research article how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact campbell l1, lau a1*, pousett b2, janzen e3, raschke s.u3 1 prosthetics and orthotics, school of health sciences, british columbia institute of technology (bcit), burnaby, british columbia, canada. 2 barber prosthetics clinic, vancouver, british columbia, canada. 3 make + applied research, centre for applied research & innovation (cari), burnaby, british columbia, canada. open access abstract background: 3d printing is becoming more popular across many industries. the first step to safely introducing 3d printed sockets in to prosthetics is to conduct strength testing on these sockets. purpose: this study tests how changing the infill percentage (the percentage of material between the internal and external socket wall) affects the strength of 3d-printed transtibial sockets. methods: a fused deposition modelling (fdm) printer was used to print a total of nine transtibial (tt) sockets (three sockets at 30% infill, three sockets at 40% infill, and three sockets at 50%) using polylactic acid (pla). a strengthtesting apparatus measured, in newtons (n), the maximum load the 3d-printed transtibial sockets could withstand at initial contact of the gait cycle. results: based on the specific criteria outlined in this research project, all nine sockets exceeded the 4480n threshold set by iso standard 10328. eight out of nine sockets failed at approximately double the force required with one socket (socket #2) failing at 5360n. seven out of nine sockets failed at the medial popliteal region and two out of nine sockets failed at lateral mid socket region. differences in infill percentage from 30%, 40%, 50% did not appear to influence strength of sockets. conclusion: strength of 3d-printed tt sockets needs rigorous testing to be deemed safe for patient use. more definitive research and a higher number of samples are required to investigate how a larger range of infill percentage can affect strength. until all the requirements of iso standard 10328 are satisfied, the safety of using 3d-printed tt sockets in clinical practice are uncertain. article info received: august 21, 2018 accepted: september 21, 2018 published: september 28, 2018 citation campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. https://doi.org/10.33137/cpoj.v1i 2.30843 keywords prosthetic socket, transtibial, 3d printing, infill percentage, strength testing, fused deposition modeling, polylactic acid. infill percentage effects on 3d-printed transtibial sockets volume 1, issue 2, article no. 2, september 2018 abbreviations fdm: fused deposition modeling fmax: maximum force fset: settling test force fsp: static proof test force pla: polylactic acid tij: thermal inkjet printing sls: selective laser sintering *corresponding author adriel lau, prosthetics and orthotics, school of health sciences, british columbia institute of technology (bcit), 3700 willingdon avenue, burnaby, british columbia, canada. email: lau.adriel@gmail.com doi: https://doi.org/10.33137/cpoj.v1i2.30843 https://doi.org/10.33137/cpoj.v1i2.30843 https://doi.org/10.33137/cpoj.v1i2.30843 https://doi.org/10.33137/cpoj.v1i2.30843 mailto:lau.adriel@gmail.com https://doi.org/10.33137/cpoj.v1i2.30843 campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30843 2 open access infill percentage effects on 3d-printed transtibial sockets volume 1, issue 2, article no. 2, september 2018 introduction 3d printing has been around for 30 years, but recently it has been making significant strides in the field of prosthetics. some prosthetics and orthotics clinics have begun to use the technology in their practice due to the decrease in cost of 3d printers as well as the development of 3d scanning technology to efficiently capture the shape of a patient’s limb.1 3d printing allows for increased cost efficiency and enhanced productivity.2 because of this, 3d-printed prosthetic sockets are becoming an alternative option to traditional methods. however, 3d-printed sockets used for weight bearing should be tested rigorously to ensure patient safety. ventola (2014) states that the three most common types of 3d printers used in medical applications are selective laser sintering (sls), thermal inkjet (tij) printing, and fused deposition modeling (fdm).2 during sls printing, a laser draws the shape of the object in powder which fuses it together. tij printing “uses thermal, electromagnetic, or piezoelectric technology to deposit tiny droplets of ‘ink’ onto a substrate according to digital instructions”.2 fdm printers lay down layers of heated beads of plastic and these build the object layer by layer. fdm printers are less expensive and more common than the sls type printers.2 for this reason, they are likely the type of printer that prosthetics and orthotics clinics will have in their clinics.2 the technology of 3d printing is advancing, but many of these designers are becoming more involved with the idea of creating prostheses when they have little to no concept of the intricacies of creating a prosthetic device nor the treatment planning involved. for example, chhaya et al (2015) discuss several online groups that provide open‐ source files available for printing upper extremity devices.3 as both prosthetists and healthcare professionals, we believe there is a need to become more involved in the process of designing and testing safe 3d-printed sockets. before additive manufacturing technology can be fully implemented in the prosthetics and orthotics field, there are barriers that must be addressed and resolved.4 strength testing to ensure that weight bearing 3d-printed sockets are safe for patient use, they should adhere to the strength standards for lower extremity prostheses. iso standard 10328 is the international standard for the structural testing of lower limb prostheses and it outlines test methods.5 iso 10328 outlines the procedures for testing lower limb prostheses both statically and cyclically.5 the static test is a one-time, single-event test to determine the performance of a structure under a specific load. the cyclic test consists of a specific load applied to a structure multiple times or for many cycles, simulating conditions of normal walking.5 lower extremity prostheses must be tested to satisfy iso 10328 standards loading condition i and ii. condition i loading “the instant of maximum loading occurring early in the stance phase of walking”.5 condition ii loading “the instant of maximum loading occurring late in the stance phase of walking”.5 there are three loading levels that can be tested in iso 10328. p5 is the loading condition that based on data from amputees with body masses are above and below 100 kg. p4 condition is for an amputee whose body mass is less than 80kg, and finally p3 condition is less than 60 kg.5 a literature search for the strength testing of 3d printed lower extremity prostheses did not produce any results. other studies have used iso standards to test the strength of non-3d printed lower extremity prostheses. gerschutz et al., (2012) conducted a study examining static failure loads on traditional sockets.6 in their study, mechanical testing on three different types of sockets was performed (thermoplastic check, copolymer and definitive laminated) for a total of n = 98 sockets. they were assessed for passing brittle failure = 4,426n and ductile failure = 3,421 n. this quantitative study evaluated socket strength to provide an understanding of the materials used for prosthetic sockets. goh et al., (2002) tested complete prostheses using both cyclic and static procedures.7 the researchers conducted the static test procedure by subjecting the prosthesis to sinusoidal loads ranging from 50n to fmax (fmax=1330n for condition i and fmax=1200n for condition ii). the force was maintained for 30s and if permanent deformation of 15mm or the prosthesis failed, the prosthesis was not found to be adhered to iso 10328 standards.7 if the prosthesis did not fail, it proceeded to the failure https://doi.org/10.33137/cpoj.v1i2.30843 campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30843 3 open access infill percentage effects on 3d-printed transtibial sockets volume 1, issue 2, article no. 2, september 2018 test. the article found that the polypropylene sockets passed the static load test with only minimal deformation and passed cyclic test of 250000 cycles with no failure. infill percentage 3d printing can change different parameters such as infill percentage. infill percentage is the density of the plastic between the inner and outer walls of a printed object.8 increasing the infill percentage on a 3dprinted transtibial (tt) socket made from polylactic acid (pla) should influence the ultimate strength of the socket. johansson (2016) states that low infill is weaker and more prone to cracking.8 whereas, printing at 100% can increase printing time and cost and may not necessarily increase strength.8 it is valuable for the prosthetics and orthotics profession to determine at what infill percentage has adequate strength, but at the same time, does not take an excessive amount of time to print. the purpose of this study was to test how changing the infill percentage affects the strength of a 3dprinted tt socket during initial contact. we hypothesized that greater infill percentage could correspond to a greater socket strength. this project collaborated with a research facility to investigate this concept and hope to be a part of a much bigger picture in progressing 3d printing as a tool to help the field of prosthetics. methods settings this experimental study printed nine identical total surface bearing (tsb) transtibial sockets. to maintain consistency, the sockets were all printed from the same data file supplied by the company additive o&p in charlotte, n.c. and barber prosthetics clinic in vancouver, b.c. the sockets were printed from a fdm printer located at barber prosthetics clinic. the fdm printer uses a nozzle head that extrudes melted plastic layer by layer to create a three-dimensional structure.2 it took an average of 8-9 hours to print each socket. the sockets were all printed using a white pla filament and were all reinforced with scotch cost. at the distal end, each socket was attached to a 5r1 wood block which served as the attachment point for the pylon in the strength testing apparatus. a registered prosthetic technician oversaw the production and finished each 3d-printed transtibial socket as can be seen in figure 1. considering the various 3d printer parameters that were available to be evaluated, the authors chose to research infill percentage as a parameter because this variable was hypothesized to have a direct relationship with strength and print time. three different infill percentages were chosen that would best represent realistic categories that clinicians may decide to print: three sockets were printed at 30% infill, three sockets at 40% infill, and three sockets at 50% infill. table 1 describes the properties of each socket. figure 1. 3d-printed tt socket table 1. characteristics of the 3d-printed sockets socket # infill % length (cm) weight unfinished (gr) finished (gr) 1 30 20.8 291 531 2 30 20.8 304 543 3 30 20.8 304 543 4 40 20.8 297 527 5 40 20.8 296 538 6 40 21 302 543 7 50 20.8 325 564 8 50 20.9 324 574 9 50 20.5 326 575 componentry this project worked closely with the centre for applied research institute (cari) in burnaby, bc to fabricate components that held the 3d-printed socket in the proper orientation for strength testing as can be seen in figure 2. the components included an upper plate and bottom plate made from one-inch thick steel. the superior part of the upper plate and the inferior part of the lower plate contain a concave surface that articulated with two hitch balls which was attached to the strength testing apparatus. firstly, this ensured a pure vertical force was generated as accurately and consistently as possible. secondly, https://doi.org/10.33137/cpoj.v1i2.30843 campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30843 4 open access infill percentage effects on 3d-printed transtibial sockets volume 1, issue 2, article no. 2, september 2018 this allowed the plates to be oriented in the correct alignment for this project. this experiment focused on initial contact of the gait cycle as iso 10328 states that during this phase, the socket experiences the largest loading force.5 lastly, the plates can be placed in different orientations to test for multiple weight classes which are specified as p3, p4, and p5. our study focused on p5 condition which is the loading condition that based on data from amputees with body masses are above and below 100 kg. figure 2 (left). componentry attached to 3d-printed socket. figure 3 (right). high-density urethane residual limb model. to simulate a residual limb, a high-density urethane mold was fabricated as seen in figure 3. the model was created from a mold of the socket shape which created an intimate fit thus simulating an appropriate fit with the tsb socket. the urethane mold and the upper plate were connected by a ⅝ bolt which allowed the load generated by the strength testing apparatus to be distributed throughout the entire socket. the bottom plate articulated with the socket through a solid piece of welded steel that acted as the pylon. since existing prosthetic componentry such as the pylon, tube clamp adaptors and pyramids have already been tested to iso standards, attempting to eliminate them from the equation is most logical to isolate the strength of the socket. therefore, a 311mm solid piece of steel was fabricated to satisfy these requirements. this piece of steel also contained a welded pyramid adaptor which allowed it to be attached to the wood block. strength testing apparatus strength testing was performed on a tinius olsen universal testing machine as seen in figure 4 (left) and focused solely on static testing. cyclic testing requires 3 million cycles,5 which would take approximately one year of continuous testing. due to time and cost constraints, only ultimate strength testing was completed. the sockets were tested for ultimate strength. ultimate strength is defined as static load representing a gross single event, which can be sustained by the prosthetic device/structure but which could render it unusable.5 the static load will be applied for testing condition i which is described as evaluating the instant of maximum loading during early stance phase or initial contact of the gait cycle. each socket was tested to iso standards where the force measurement data was gathered in newtons (n). 4480n was the force required in order to pass the standards outlined in iso 10338.5 furthermore, if the sockets surpassed the threshold, they were subjected to further testing and compressed to failure to determine how much force is required before breaking the socket. the procedure for principal static ultimate strength test as per iso standard 10328 is as follows: a force was steadily increased at a constant rate between 100 n/s and 250 n/s to 2240 n and held for 10-30 seconds (values are recorded). the force was removed and the socket rested at zero load for one minute. the force was again steadily increased at a constant rate between 100 n/s and 250 n/s to 4480 n and held for 30 seconds (values are recorded). if the socket had not failed, a compression force continued and the load was increased until failure was reached. figure 4 (right) provides a visual representation of the 3d-printed socket attached to all the componentry. results force at socket failure the results of the strength testing procedure were recorded in table 2. these recordings include the settling test force (fset), the amount of time each socket spent at fset, the amount of time the socket spent with no force between fset and the static proof test (fsp), the actual force at fsp, the time the socket spent at fsp, the force that the socket ultimately https://doi.org/10.33137/cpoj.v1i2.30843 campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30843 5 open access infill percentage effects on 3d-printed transtibial sockets volume 1, issue 2, article no. 2, september 2018 failed at, and whether the socket passed the minimum force dictated in the iso standard 10328. table 2. results of loading procedure (note: fset = settling test force, fsp = static proof test force). both the fset and fsp forces listed in table 2 are different for each socket due to the setting capabilities of the strength testing apparatus. the apparatus was controlled via a dial, so a specific set point for both fset and fsp was not possible. the accuracy of these points depended solely on the operator of the strength testing apparatus pausing the loading at a force close to the intended forces (laid out in the methods) of fset = 1024 n and fsp= 2240 n. figure 5 shows the force at failure of all 3d-printed sockets. the black threshold line indicates the minimum threshold (4480 n) that the iso standards dictates for condition i, weight class p5. as shown in figure 6, all the sockets surpassed the threshold and all sockets (with the exception of socket number 2) failed at approximately double the force required by iso standards figure 5. all 3d printed transtibial sockets failed above the iso standard for this condition. visual analysis of socket failure table 3 shows the area that the sockets failed at as well as the type of socket failure. most sockets failed in the medial popliteal region (seven of nine sockets) and two of the nine sockets failed in the lateral mid socket region. an example of a medial popliteal area socket failure is shown in figure 6 (left). figure 6 (right) shows an example of a socket failing in the lateral mid socket. table 3. area of socket failure and failure type socket # infill % failure point failure type 1 30 medial popliteal crack 2 30 lateral mid socket crack 3 30 medial popliteal complete 4 40 medial popliteal crack 5 40 lateral mid socket crack 6 40 medial popliteal crack 7 50 medial popliteal complete 8 50 medial popliteal crack 9 50 medial popliteal crack figure 6. left: socket broken in the medial popliteal area; right: socket broken in the middle lateral area. s o c k e t # in fi ll % f s e t (n ) f s e t ti m e (s ) t o ta l re s t ti m e ( s ) f s p ( n ) f s p t im e (s ) f o rc e a t fa ilu re ( n ) p a s s m in im u m (4 4 8 0 n ) 1 30 1079 15 60 2630 30 11854 y 2 30 1074 10 60 2438 30 5360 y 3 30 1070 10 60 2303 30 12841 y 4 40 1114 10 60 2314 30 9009 y 5 40 1147 10 60 2425 30 10345 y 6 40 1216 10 60 2266 30 11383 y 7 50 1252 10 60 3457 30 11965 y 8 50 1115 10 60 2371 30 12243 y 9 50 1177 10 60 2491 30 9847 y figure 4. left: tinius olsen universal testing apparatus; right: completed set-up. https://doi.org/10.33137/cpoj.v1i2.30843 campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30843 6 open access infill percentage effects on 3d-printed transtibial sockets volume 1, issue 2, article no. 2, september 2018 table 3 shows that the primary method for socket failure was a crack in the socket (seven of the nine sockets). a crack failure type was defined as a failure in which the proximal and distal aspects of the socket remained attached. figure 6 shows examples of a crack failure. figure 7 shows an example of a complete failure of the socket. in this case, the proximal and distal aspects of the socket are completely separated from each other. two of the nine sockets failed in this manner. figure 7: complete socket failure discussion the purpose of this research project was to evaluate how changing infill percentage would affect the ultimate strength of a 3d-printed tt socket. to safely use these sockets in either a diagnostic or a definitive phase, the efficacy and effectiveness of these devices must be clearly shown.9 3d-printed sockets should satisfy the same requirements as lower limb conventional prostheses as stated in iso standards 10328. based on the results, the sockets in this study exceeded the threshold of 4480 n. however, it is important to note that the sockets were evaluated with a specific set of criteria. the conditions of static testing, initial contact (condition i) and p5 weight class were implemented and only under these conditions did all of the sockets exceed the threshold. to fully deem a 3d-printed socket safe for patient use, the other criteria explained in iso standard 10328 will also need to be satisfied. for example, cyclic testing needs to be performed where the socket is continuously compressed through a low load, long duration setting. this will better simulate a socket when completing activities of daily living. furthermore, it has been seen in clinical practice that sockets often fail during terminal stance in the gait cycle. testing in this specific phase of the gait cycle in addition to initial contact, will provide a more encompassing picture as an individual ambulates. testing each of these conditions in all the weight classes (p3, p4 and p5) will also need to be completed to fully satisfy safety requirements. the infill percentage did not appear to influence the ultimate strength of the sockets. it was hypothesized that a greater infill percentage would require a greater force for a socket to fail. however, the results show that all the sockets failed at approximately twice the required force (except for socket #2). perhaps the range of infill percentage was not large enough to see a difference in ultimate strength. in the future, choosing a larger gap in infill percentage may show difference in the force values required for a socket to fail. another possible explanation for this result is that the other parameters used for the sockets were structurally weaker so the infill percentage was not the factor that influenced failure. the failure points occurred in different areas of the socket during the experiment; however, it was observed that all the failure points occurred above the reinforced scotch cast. with a diagnostic socket, it is more advantageous that reinforcement methods be done to create additional strength and stability. with the breaks occurring above this area, this suggests that the reinforced area is successful in delegating the force to an area that is less strong. knowing this, removing the reinforced scotch cast in might have shown different results when evaluating for ultimate strength. as mentioned earlier, the sockets broke in different areas with seven of the nine sockets failing on the medial popliteal area and two of the nine sockets failing at the middle, lateral area of socket. two of the sockets also experienced complete failure where the socket was broken into two separate pieces. there was no predictability and no trend was seen as to how a socket broke compared to its failure values. limitations the limitations of this study included the small sample size of sockets. due to cost and time constraints, only nine sockets were printed as this was a logical way to compare sockets printed at different infill percentages. because of the small sample size, we were unable to comment on any significant differences and can only comment on https://doi.org/10.33137/cpoj.v1i2.30843 campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30843 7 open access infill percentage effects on 3d-printed transtibial sockets volume 1, issue 2, article no. 2, september 2018 general trends. future studies should focus on printing a larger number of sockets encompassing a wider variety of infill percentages which could enable the generation of a statistical analysis. in general, more testing is needed to be done on the strength of 3d-printed sockets. the settings of 3d printing can be optimized and customized to the user or practitioner’s preferences. as a result, evaluating how individual parameters affect the strength of a socket would be beneficial. this study focused on infill percentage as an attempt to isolate its effects and how changing this setting would ultimately affect its strength. no articles were found regarding the evaluation of the ultimate strength of a 3d-printed tt socket. 3d printing is a relatively new technology in the field; therefore, there is not enough data currently to perform meta-analysis. there are also no randomized control trials to investigate the efficacy of these sockets which created a challenge in narrowing down the testing procedures and methodology process. with 3d printing technology advancing at an impressive rate, future directions should consider investigating how different printers, different materials and how different methods of printing can affect the strength of a socket. conclusion 3d printing technology is currently being used in many different industries. the field of prosthetics and orthotics needs to embrace this technology and demonstrate how it can be successfully used in clinical practice. a logical first step is testing the strength of 3d-printed prosthetic sockets to determine if it is safe for patient use. this research project demonstrated that the amount of force required for a socket to fail exceeded the 4480n threshold set by iso standard 10328. furthermore, infill percentages ranging from 30% to 50% did not seem to affect the ultimate strength of the sockets. however, it should be noted that the sockets were tested to specific and limited criteria (static testing, initial contact and p5 weight class). this project is a stepping stone to much more extensive research and as such, further work is recommended to investigate how different parameters can influence the strength of socket. moreover, additional conditions outlined by the iso standards need to also be satisfied to determine if 3d-printed prosthetic sockets are safe and suitable for patients. acknowledgement the authors would like to thank dave moe (cp), daryl murphy (rtp), and malena rapaport (cp) from barber prosthetics clinic. the authors would also like to thank additive o&p, the centre for applied research institute, dr. nathan devos and caroline soo for their guidance and support throughout this project. declaration of conflicting interests barber prosthetics clinic donated the use of their 3d printer and the pla used to print the sockets. the researchers did not receive any financial compensation for this project. ethical approval not required author contribution • leah campbell: conceptualization, formal analysis, investigation, methodology, visualization, writing original, review & editing. • adriel lau: conceptualization, formal analysis, investigation, methodology, visualization, writing original, review & editing. • brittany pousett: conceptualization, investigation, visualization, supervision, review & editing. • ernie janzen: investigation, visualization, methodology, review & editing. • silvia ursula raschke: conceptualization, visualization, review & editing. references 1) daly a. socio-legal aspects of the 3d printing revolution: palgrave macmillan uk. 2016, doi: 10.1057/978-1-137-51556-8. 2) ventola c.l. medical applications for 3d printing: current and projected uses. p & t : a peer-reviewed journal for formulary management. 2014; 39(10), 704– 711. 3) chhaya m.p, poh p.s, balmayor e.r, griensven m, schantz j.t, hutmacher d.w. additive manufacturing in biomedical sciences and the need for definitions and norms. expert review of medical devices. 2015; 12(5), 537–543. doi:10.1586/17434440.2015.1059274 https://doi.org/10.33137/cpoj.v1i2.30843 https://doi.org/10.1586/17434440.2015.1059274 campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3d-printed transtibial sockets during initial contact. canadian prosthetics & orthotics journal, volume 1, issue 2, no 2, 2018. doi: https://doi.org/10.33137/cpoj.v1i2.30843 8 open access infill percentage effects on 3d-printed transtibial sockets volume 1, issue 2, article no. 2, september 2018 4) chen r.k, jin y, wensman j, shih a. additive manufacturing of custom orthoses and prostheses-a review. additive manufacturing. 2016;12,77-89. doi.org/10.1016/j.addma.2016.04.002. 5) international organization for standardization. prosthetics-structural testing of lower limb prosthesesrequirements and test methods (iso 10328), 2006. 6) gerschutz m.j, haynes m.l, nixon d, colvin j.m. strength evaluation of prosthetic check sockets, copolymer sockets, and definitive laminated sockets. journal of rehabilitation research and development. 2012; 49(3), 405–426. http://dx.doi.org/10.1682/jrrd.2011.05.0091 7) goh j.c, lee p.v, ng p. structural integrity of polypropylene prosthetic sockets manufactured using the polymer deposition technique. proceedings of the institution of mechanical engineers, part h: journal of engineering in medicine. 2002; 216(6), 359–368. https://doi.org/10.1243/095441102321032157 8) johansson f. optimizing fused filament fabrication 3d printing for durability: tensile properties and layer bonding (dissertation). 2016; retrieved from: http://urn.kb.se/resolve?urn=urn:nbn:se:bth-12355 9) diment l.e, thompson m.s, bergmann j.h.m. threedimensional printed upper-limb prostheses lack randomised controlled trials: a systematic review. prosthetics and orthotics international. 2018; 42(1), 7–13. https://doi.org/10.1177/0309364617704803. https://doi.org/10.33137/cpoj.v1i2.30843 http://dx.doi.org/10.1682/jrrd.2011.05.0091 https://doi.org/10.1243/095441102321032157 http://urn.kb.se/resolve?urn=urn:nbn:se:bth-12355 https://doi.org/10.1177/0309364617704803 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 review article lee dj, repole t, taussig e, edwards s, misegades j, guerra j, lisle a. self-management in persons with limb loss: a systematic review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.5. https://doi.org/10.33137/cpoj.v4i1.35098 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.35098 1 lee dj, repole t, taussig e, edwards s, misegades j, guerra j, lisle a. self-management in persons with limb loss: a systematic review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.5. https://doi.org/10.33137/cpoj.v4i1.35098 review article self-management in persons with limb loss: a systematic review lee dj*, repole t, taussig e, edwards s, misegades j, guerra j, lisle a touro college, department of physical therapy, bayshore, ny, usa. introduction in the united states, approximately 2 million individuals are living with limb loss.1 common etiologies that may lead to amputation include trauma, cancer, and vascular complications secondary to diabetes.2 regardless of the etiology of amputation, living without a limb requires biopsychosocial and behavioral adaptations to successfully reintegrate into society.3,4 while biopsychosocial adaptations may be learned through the experience of participating in a comprehensive rehabilitation program,5 the behavioral aspects related to lifestyle changes and selfcare may go under-emphasized. these behavioral and lifestyle changes for a person with limb loss specifically involve caring for the residual limb and prosthesis, as well as the interface between the two. when considered as a whole, the behavior and lifestyle changes are known as selfmanagement, a term used to describe the daily adaptions one must make when faced with a chronic condition.6,7 open access volume 4, issue 1, article no.5. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: self-management is an integral component of managing long-term conditions and diseases. for a person with limb loss, this self-management process involves caring for the residual limb, the prosthesis, and the prosthetic socket-residual limb interface. failure to properly self-manage can result in unwanted secondary complications such as skin breakdown, falls, or non-use of the prosthesis. however, there is little evidence on what self-management interventions are effective at preventing secondary complications. to understand the impact of self-management after the loss of a limb, it is necessary to determine what the current evidence base supports. objective(s): the purpose of this study is to examine the available literature on self-management interventions and/or outcomes for persons with limb loss and describe how it may impact residual limb health or prosthesis use. methodology: a systematic review of multiple databases was carried out using a variety of search terms associated with self-management. the results were reviewed and selected based on the inclusion criteria: self-management interventions or direct outcomes related to self-management, which includes the skin integrity of the residual limb, problem-solving the fit of the prosthesis, and education in the prevention of secondary complications associated with prosthesis use. the cincinnati childrens’ legend (let evidence guide every new decision) appraisal forms were used to analyze the articles and assign grades. findings: out of the 40 articles identified for possible inclusion in this study, 33 were excluded resulting in seven articles being selected for this review. three out of the seven articles focused on silicone liner management while the other four articles focused on skin issues. conclusion: self-management for a person with limb loss is a key component of preventing complications associated with loss of limb and prosthesis use. there is a lack of high-quality experimental studies exploring the most appropriate intervention for teaching self-management when compared to other conditions, specifically diabetes. further research in the area of self-management is necessary to understand how to best prevent unwanted secondary complications. article info received: february 18, 2021 accepted: may 24, 2021 published: june 4, 2021 citation lee dj, repole t, taussig e, edwards s, misegades j, guerra j, lisle a. selfmanagement in persons with limb loss: a systematic review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.5. https://doi.org/10.33137/cpoj.v4i 1.35098 keywords self-management, limb loss, prosthesis, amputation, systematic review * corresponding author daniel j. lee, pt, phd, dpt, gcs, comt touro college, department of physical therapy, bayshore, ny usa. e-mail: daniel.lee29@touro.edu orcid number: 0000-0003-1805-2936 https://doi.org/10.33137/cpoj.v4i1.35098 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.35098 https://doi.org/10.33137/cpoj.v4i1.35098 mailto:daniel.lee29@touro.edu 2 lee dj, repole t, taussig e, edwards s, misegades j, guerra j, lisle a. self-management in persons with limb loss: a systematic review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.5. https://doi.org/10.33137/cpoj.v4i1.35098 issn: 2561-987x self-management in persons with limb loss lee et al. 2021 cpoj while a universal definition of self-management after amputation is deficient, it is agreed that optimal selfmanagement requires the patient to be an active participant in decisions regarding their health and own care.8 for persons with limb loss, this can be thought of in three distinctive categories: residual limb care and hygiene, problem-solving the fit of the prosthesis, and making decisions regarding self-care.9 these decisions surrounding the daily self-care and hygiene associated with residual limb includes washing regimens, liner cleaning and drying, skin inspection, and wound prevention.10 selfmanagement also involves problem-solving the fit of the prosthesis, which may include modification of sock-ply, sequencing components for donning, and maintaining awareness of how the fit changes throughout the day.11 finally, decision-making is concerned with recognizing when an issue presents, such as skin breakdown, and properly contacting the correct medical professional for assistance.12 if self-management is not embodied and embraced by persons with limb loss they may be at an increased risk of injury, including but not limited to skin breakdown, wound formation, musculoskeletal issues, or falls.13-15 conversely, proper self-management may be related to better outcomes after loss of limb, including maintaining the integrity of the skin, preventing wound formation, and improving quality of life.10,16 currently, the greatest resources of selfmanagement education are found in clinical textbooks, patient handouts, and through professional organizations. however, despite the importance of self-management, there is a relative paucity of peer-reviewed materials on the subject published in scientific journals specific to which intervention is the most efficacious. while other conditions like diabetes mellitus have well established pathways for assessing and imparting self-management knowledge and behaviors,17-23 self-management after limb loss has not received the same level of attention in the scientific literature. to fully comprehend the impact of selfmanagement after loss of limb, it is necessary to determine what the current evidence base supports. therefore, the purpose of this study is to examine the available published literature on self-management interventions and/or outcomes for persons with limb loss and describe how it may impact residual limb health or prosthesis use. methodology criteria for studies considered types of studies the study types considered for review were mixed methodologies, retrospective studies, case reports, randomized control trials, and qualitative studies. participants of any age, gender, background, and limb deficiency were included if self-management was emphasized. inclusion criteria consisted of studies that assessed functional outcome measures related to selfmanagement, participants of any age or gender, and individuals with upper or lower limb amputation or limb deficiency. articles published between january 1965 and september 2019 were considered eligible for review. exclusion criteria were studies published in a language other than english and opinion-based papers. non-peer reviewed publications (e.g. textbooks, patient education materials) were excluded. search strategy a computerized literature search was conducted from september 2019 to december 2019 by the research team. the search strategy of this review consisted of combining keywords related to the self-management of individuals with limb loss into search permutations. each permutation was inputted into five databases: pubmed, cochrane library, pedro, google scholar and psycnet. this strategy was developed to locate published studies relevant to individuals with amputations or limb differences and the individual’s ability to self-manage their residual limb or the residual limbprosthesis interface. because there are many terms synonymous with limb loss and self-management different combinations of keywords were used. search keywords are presented in table 1. selection and rating the study eligibility flowchart is presented in figure 1. the initial search provided numerous results from the keywords used for the search. many of the results from this initial search were not explicitly related to the topic of selfmanagement in persons with limb loss. results excluded at this stage were studies that focused on prosthetics for other anatomical structures and health conditions. article duplicates and non-english studies were then excluded. the remaining 40 articles had an initial face value of being eligible for this systematic review, however upon further examination many focused towards quality of life in those with limb loss rather than self-management of the limbsocket interface. the final remaining 11 articles underwent full evaluation for inclusion. given the diversity of study designs represented in the literature, the evaluative tool needed to be flexible enough to account for the variety of results. the cincinnati childrens’ legend (let evidence guide every new decision) appraisal forms was determined to be the best fit. the legend tool is a series of appraisal forms designed to help clinicians synthesize evidence and determine the quality of published studies of different designs.24 the legend scale uses an algorithm to derive a grade of either good or lesser quality, then based on the summative quality of each review an overall score is given base on the types of studies included. https://doi.org/10.33137/cpoj.v4i1.35098 3 lee dj, repole t, taussig e, edwards s, misegades j, guerra j, lisle a. self-management in persons with limb loss: a systematic review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.5. https://doi.org/10.33137/cpoj.v4i1.35098 issn: 2561-987x self-management in persons with limb loss lee et al. 2021 cpoj six of the reviewers were put into pairs and each pair was assigned four studies to review. each reviewer independently assessed the quality of their assigned studies according to a standardized form determined by the study design, and then scores were compared. if there was a disagreement, a third reviewer assessed the study. table 1: search keywords. keywords related to “amputee” keywords related to “selfmanagement” amputee amputation prosthetic prosthetic leg prosthesis residual limb limb loss care caring self-care self-evaluation self-managed self-management self-managing self-manage evaluation management problem solve problem solving education fluid fluctuation volume fluid loss donning doffing socket socket fit prosthetic fit figure 1: article eligibility flow chart. results the majority of participants were males (approximate mean age of 61 years) with acquired transtibial level amputations. no randomized control trials including self-management interventions were included. of the seven included articles, most were of good quality and focused on education and training. table 2 presents a summary of articles and demographic characteristics. the specific breakdown of each included article can be found in table 3. table 2: summary of the seven included articles and demographic characteristics. article characteristics historical cohort qualitative case report descriptive quality of studies good quality lesser quality self-management impact of hand function efficacy of education and training self-management practices prosthetic prescriptions 1 2 2 2 4 3 1 3 1 2 participants (259 people) males females not disclosed age range approximate mean age level of amputation trans-femoral knee disarticulation trans-tibial symes not disclosed (includes ue and le) type of limb loss acquired congenital not disclosed 185 54 20 18-90 61 33 13 128 8 77 250 7 2 discussion the purpose of this study was to examine the available literature on self-management interventions and/or outcomes for persons with limb loss and describe how it may impact residual limb health and prosthesis use. despite a systematic search in multiple databases, only seven articles were found to directly address the inclusion criteria of this study. full-text articles deemed eligible (n=7) full-text articles rated with quality assessment tool (n=11) full-text articles assessed for eligibility (n=40) articles excluded (not meeting inclusion criteria) (n=280) articles after duplicates removed (n=320) articles retained from initial search (n=413) articles identified from each keyword (n=41,712) https://doi.org/10.33137/cpoj.v4i1.35098 4 lee dj, repole t, taussig e, edwards s, misegades j, guerra j, lisle a. self-management in persons with limb loss: a systematic review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.5. https://doi.org/10.33137/cpoj.v4i1.35098 issn: 2561-987x self-management in persons with limb loss lee et al. 2021 cpoj article title (year) number of participants and age (sd) level of amputation legend grade article type outcomes of interest/intervention results skin problems of the stump and hand function in lower limb amputations (2008)25 n=60 (43 m, 17 f) age: 62.3 (15.4) tt (50) kd (10) good quality (4a) historic cohort explorative study relationship between impaired hand function and liner-related skin problems of the residual limb. impaired hand function was significantly related to liner-related skin problems. the effect of prosthetic rehabilitation in lower limb amputees (1995)26 n=29 (22 m, 7 f) age: 64 (n/a) tt (19) tf (10) lesser quality (4b) qualitative (questionna ire) efficacy of training following prosthesis prescription in promoting constant use of the prosthesis. more effective communication between the patient and healthcare team is needed. improper use of a transtibial prosthesis silicone liner causing pressure ulceration (2009)27 n=1 (m) age: 80 tt good quality (5a) case report importance of appropriate candidate selection for roll-on liners, proper patient and professional training, and management of patient comorbidities. pressure ulcers may be prevented with proper education of caregivers and patients in correct use of all prosthetic components. knowledge and skill of patients with regard to amputations stump bandaging, prior to a prosthesis (1998)28 n=33 (21 m, 12 f) age: 23-78 (average age and sd not specified) lla lesser quality (4b) descriptive study knowledge and skill of patients with regard to residual limb bandaging prior to fitting of a prosthesis. success post-amputation is highly dependent on the quality of education on residual limb bandaging given. success post-amputation is highly dependent on the quality of education on correct residual limb bandaging. issues of importance reported by persons with lower limb amputations and prostheses (1999)29 n=92 (79 m, 13 f) age: 55 (n/a) through the knee, tt, symes good quality (4a) descriptive study improve decisions related to amputation levels and prosthetic prescription. fit of the prosthesis socket with the residual limb, aspects of mechanical functioning of the prosthesis, other nonmechanical qualities, and advice about adaptation to life with a prosthesis with support from others are the major themes deemed important to those living with lla. incorporating selfmanagement in prosthetic rehabilitation: case report of an integrated knowledge-toaction process (2015)30 n=20 (sex not specified) age: adult lla good quality (5a) case report knowledge-to-action process for prosthesis self-management education. group training adds value to the prosthesis management education process. staying "just normal": preservation strategies in prosthesis use (2019)31 n=24 (19 m, 5 f) age: 43.89 (12.66) upper and lower limb loss (7 congenital, 17 acquired, 2 not disclosed) lesser quality (4b) qualitative grounded theory practices used by persons with lla to manage their prosthetic limbs. individuals use a variety of preservation strategies to manage threats and limitations of prostheses in order to live “normally” with a prosthesis. abbreviation: sd, standard deviation; n, number; m, male; f, female; tt, trans-tibial; kd, knee disarticulation; tf, trans-femoral; lla, lower limb amputation table 3: overview of studies included in the literature review. https://doi.org/10.33137/cpoj.v4i1.35098 5 lee dj, repole t, taussig e, edwards s, misegades j, guerra j, lisle a. self-management in persons with limb loss: a systematic review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.5. https://doi.org/10.33137/cpoj.v4i1.35098 issn: 2561-987x self-management in persons with limb loss lee et al. 2021 cpoj this is in contrast to diabetes, where a perfunctory search of pubmed using the terms “self-management” and “diabetes” results in thousands of results, including a metaanalysis of systematic reviews.32 this brings attention to the lack of self-management-focused research in the limb loss literature as compared to other fields. since the link between self-management and prevention of secondary complications is well established,13,33,34 the lack of strong evidence made apparent by this review limits the ability to provide significant clinical recommendations. review of studies when looking at the results of the review it is evident that certain aspects of self-management are promoted regardless of the study, namely the prevention of wound development, proper limb shaping, and contracture prevention. considering that re-ulceration rates after certain amputations are as high as 70%35 it is conceivable that wound prevention is of the utmost importance. additionally, contracture prevention through exercise and posturing,36 as well as limb shaping via bandaging remains a common practice37,38 and should be taught as a basic element of selfmanagement education. three of the seven articles 25,27,29 directly addressed issues with silicone liners. silicone liners are commonly used to suspend the prosthetic socket or decrease discomfort from weight-bearing. however, silicone liners have many issues, including creating an inhospitable environment for the residual limb that promotes excessive sweating.39 while silicone liners can be used after the initial amputation incision is closed to help shape the limb and decrease the time required for the rehabilitation stay,40 they can also result in skin breakdown if donned incorrectly, as exemplified in the case report by bruno & kirby.27 therefore, it is of critical importance that proper liner donning be taught as a foundational element of the selfmanagement education process after loss of limb. beyond just educating on proper self-management, it may also be necessary to examine the hand strength of the patient as it was shown that those hand impairments are more likely to have skin issues related to liner use.25 considering that older adults have both lower hand strength, more cognitive impairments, and are more likely to experience a lower limb amputation due to a dysvascular condition, the consideration of hand strength in the prescription of a silicone liner should be prioritized.41,42 bandaging remains common practice, however evidence may suggest that the use of rigid removal dressings may have greater benefit.37,43 given the relative ease of donning and doffing, a rigid removable dressing benefits the patient by helping shape the limb, prevent contractures, and protect the limb from environmental impacts.44 despite the benefits of a rigid removable dressing, elastic bandages are still frequently used, likely due to their ubiquitous and affordable nature. since elastic bandaging comes with inherent risk of injury due to improper donning, education on how to properly apply, remove, and check the fit is necessary.45 therefore, proper self-management education on elastic bandage should be performed for any patient using this intervention. one of the included studies looked at the benefits of group training when learning to self-manage and use a prosthesis.30 this practice demonstrated both benefits and drawbacks. the benefits include the ability to socialize, learn from each other, and share in the experience. the drawbacks were that an individual participant in the group setting may offset the benefits based on their actions and beliefs. while self-management can effectively be taught through support groups,46 one-on-one educational sessions may still be necessary given the variability in learning styles inherent to learners. the final study included in this review examined the behaviors and adaptations that need to be made after loss of limb to maintain a state of normalcy.31 the behaviors identified in the study (vigilant self-awareness, threat identification, and risk avoidance) are key components of self-managing after loss of a limb. this study identifies that a person with limb loss must be proficient in selfmanagement to maintain a degree of stability and normalcy in their lives. otherwise, a failure to self-manage can result in a disruption to their established routine, fracturing the state of normalcy that they have re-established since amputation. quality issues while the intent of this review was help guide clinical practice in terms of how to best educate the patient on selfmanagement, the paucity of evidence makes this difficult. this is due to the lack of high-quality evidence in the form of randomized control trials and interventional studies. as a result of the lack of primary sources of evidence, lower tier levels of evidence were the only included studies in this review. while descriptive, cohort, qualitative, and case studies are all beneficial in understanding the scope of the current self-management educational interventions, none of the included studies had a comparison group to determine if a specific intervention type was more effective. future focus while systematic reviews such as this one brings attention to the need for more research in this area, it makes comparing intervention effectiveness difficult at this junction. as such, there are no explicit interventions for selfmanagement that can be recommended above others. to rectify this situation, future studies are needed to determine if a specific self-management intervention may benefit persons with limb loss more than the current model which depends on clinical expertise, textbooks, and extant patient https://doi.org/10.33137/cpoj.v4i1.35098 6 lee dj, repole t, taussig e, edwards s, misegades j, guerra j, lisle a. self-management in persons with limb loss: a systematic review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.5. https://doi.org/10.33137/cpoj.v4i1.35098 issn: 2561-987x self-management in persons with limb loss lee et al. 2021 cpoj education material. the field of limb loss rehabilitation could benefit from the model used in study of diabetes which has explored numerous modes of delivering self-management education and their comparative effectiveness. therefore, funding opportunities should recognize this gap in the literature and support high-quality interventional research studies in order to bolster the body evidence supporting selfmanagement for persons of limb loss. conclusion self-management is key in the prevention of secondary complications associated with the residual limb, the prosthesis, and the interface between the residual limb and socket. research needs to be done on appropriate selfmanagement techniques, education, and implementation. both the patient and their healthcare providers need to be active and engaged throughout the self-management process. acknowledgements the authors would like to acknowledge touro college's school of health sciences for their support in conducting and publishing this study. declaration of conflicting interests the authors have no conflicting interests to disclose. author contribution all authors contributed equally in the preparation of this manuscript. sources of support there were no external sources of support to facilitate the completion of this work. ethical approval ethical approval was not needed for this study. references 1.ziegler-graham k, mackenzie ej, ephraim pl, travison tg, brookmeyer r. estimating the prevalence of limb loss in the united states: 2005 to 2050. arch phys med rehabil. 2008;89(3):422-9. doi: 10.1016/j.apmr.2007.11.005 2.lee dj, wininger m, mahler d, parisi m. taxonomy of clinical encounters during the first 90 days post-delivery of an initial lower limb prosthesis. prosthet orthot int. 2018;42(5):490-7. doi:10.1177/0309364618774053 3.horgan o, maclachlan m. psychosocial adjustment to lower-limb amputation: a review. disabil rehabil. 2004;26(14-15):837-50. doi:10.1080/09638280410001708869 4.webster jb, crunkhorn a, sall j, highsmith mj, pruziner a, randolph bj. clinical practice guidelines for the rehabilitation of lower limb amputation: an update from the department of veterans affairs and department of defense. am j phys med rehabil. 2019;98(9):820-9. doi:10.1097/phm.0000000000001213 5.esquenazi a, digiacomo r. rehabilitation after amputation. j am podiatr med assoc. 2001;91(1):13-22. doi:10.7547/87507315-911-13 6.foster g, taylor sjc, eldridge s, ramsay j, griffiths cj. selfmanagement education programmes by lay leaders for people with chronic conditions. cochrane database syst rev. 2007;(4). doi:10.1002/14651858.cd005108.pub2 7.jonkman nh, schuurmans mj, jaarsma t, shortridge-baggett lm, hoes aw, trappenburg jca. self-management 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adults with type 2 diabetes: a self-regulation perspective. diabet med. 2015;32(11):1504-12. doi:10.1111/dme.12745 21.nugent le, carson m, zammitt nn, smith gd, wallston ka. health value & perceived control over health: behavioural constructs to support type 2 diabetes self-management in clinical practice. j clin nurs. 2015;24(15-16):2201-10. doi:10.1111/jocn.12878 22.holmen h, torbjornsen a, wahl ak, jenum ak, smastuen mc, arsand e, et al. a mobile health intervention for self-management and lifestyle change for persons with type 2 diabetes, part 2: oneyear results from the norwegian randomized controlled trial renewing health. jmir mhealth and uhealth. 2014;2(4):e57. doi:10.2196/mhealth.3882 23.wilkinson a, whitehead l, ritchie l. factors influencing the ability to self-manage diabetes for adults living with type 1 or 2 diabetes. int j nurs stud. 2014;51(1):111-22. doi:10.1016/j.ijnurstu.2013.01.006 24.clark e, burkett k, stanko-lopp d. let evidence guide every new decision (legend): an evidence evaluation system for pointof-care clinicians and guideline development teams. j eval clin pract.2009;15(6):1054-60.doi:10.1111/j.1365-2753.2009.01314.x 25.baars ec, dijkstra pu, geertzen jh. skin problems of the stump and hand function in lower limb amputees: a historic cohort study. prosthet orthot int. 2008;32(2):179-85. doi:10.1080/ 03093640802016456 26.christensen b, ellegaard b, bretler u, ostrup el. the effect of prosthetic rehabilitation in lower limb amputees. prosthet orthot int. 1995;19(1):46-52. doi:10.3109/03093649509078231 27.bruno tr, kirby rl. improper use of a transtibial prosthesis silicone liner causing pressure ulceration. am j phys med rehabil. 2009;88(4):264-6. doi:10.1097/phm.0b013e31818dfdc9 28.visser c. knowledge and skill of patients with regard to amputation stump bandaging, prior to a prosthesis. s afr j physiother. 1998;54:8-10. doi:10.4102/sajp.v54i3.588 29.legro mw, reiber g, del aguila m, ajax mj, boone da, larsen ja, et al. issues of importance reported by persons with lower limb amputations and prostheses. j rehabil res dev. 1999;36(3):15563. https://pubmed.ncbi.nlm.nih.gov/10659798/ 30.van twillert s, postema k, geertzen jh, lettinga at. incorporating self-management in prosthetic rehabilitation: case report of an integrated knowledge-to-action process. phys ther. 2015;95(4):640-7. doi:10.2522/ptj.20130489 31.jefferies p, gallagher p, philbin m. staying "just normal": preservation strategies in prosthesis use. disabil. rehabil.: assist. technol. 2019;14(4):379-85. doi:10.1080/17483107.2018. 1451561 32.captieux m, pearce g, parke hl, epiphaniou e, wild s, taylor sjc, et al. supported self-management for people with type 2 diabetes: a meta-review of quantitative systematic reviews. bmj open. 2018;8(12):e024262. doi:10.1136/bmjopen-2018-024262 33.hachisuka k, nakamura t, ohmine s, shitama h, shinkoda k. hygiene problems of residual limb and silicone liners in transtibial amputees wearing the total surface bearing socket. arch phys med rehabil. 2001;82(9):1286-90. doi:10.1053/apmr.2001.25154 34.sanders je, fatone s. residual limb volume change: systematic review of measurement and management. j rehabil res dev. 2011;48(8):949-86. doi:10.1682/jrrd.2010.09.0189 35.molines-barroso rj, lázaro-martínez jl, aragón-sánchez j, garcía-morales e, beneit-montesinos jv, álvaro-afonso fj. analysis of transfer lesions in patients who underwent surgery for diabetic foot ulcers located on the plantar aspect of the metatarsal heads. diabet med. 2013;30(8):973–6. doi:10.1111/dme.12202 36.ghazali mf, abd razak na, abu osman na, gholizadeh h. awareness, potential factors, and post-amputation care of stump flexion contractures among transtibial amputees. turk j phys med rehabil. 2018;64(3):268-76. doi: 10.5606/tftrd.2018.1668 37.punziano a, martelli s, sotgiu v, giovannico g, rahinò a, cannone m, et al. the effectiveness of the elastic bandage in reducing residual limb volume in patients with lower limb amputation: literature review. assist inferm ric. 2011;30(4):208-14. doi:10.1702/1007.10959 38.koonalinthip n, sukthongsa a, janchai s. comparison of removable rigid dressing and elastic bandage for residual limb maturation in transtibial amputees: a randomized controlled trial. arch phys med rehabil. 2020;101(10):1683-8. doi:10.1016/ j.apmr.2020.05.009 39.ghoseiri k, safari mr. prevalence of heat and perspiration discomfort inside prostheses: literature review. j rehabil res dev. 2014;51(6):855–68. doi:10.1682/jrrd.2013.06.0133 40.chin t, toda m. results of prosthetic rehabilitation on managing transtibial vascular amputation with silicone liner after wound closure. j int med res. 2016;44(4):957-67. doi: 10.1177/ 0300060516647554 41.vermeulen j, neyens jcl, spreeuwenberg md, van rossum e, hewson dj, de witte lp. measuring grip strength in older adults: comparing the grip-ball with the jamar dynamometer. j geriatr phys ther. 2015;38(3):148-53. doi:10.1519/ jpt.0000000000000034 https://doi.org/10.33137/cpoj.v4i1.35098 8 lee dj, repole t, taussig e, edwards s, misegades j, guerra j, lisle a. self-management in persons with limb loss: a systematic review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.5. https://doi.org/10.33137/cpoj.v4i1.35098 issn: 2561-987x self-management in persons with limb loss lee et al. 2021 cpoj 42.lee dj, costello mc. the effect of cognitive impairment on prosthesis use in older adults who underwent amputation due to vascular-related etiology: a systematic review of the literature. prosthet orthot int. 2018;42(2):144-52. doi:10.1177/ 0309364617695883 43.mueller mj. comparison of removable rigid dressings and elastic bandages in preprosthetic management of patients with below-knee amputations. phys ther. 1982;62(10):1438-41. doi:10.1093/ptj/62.10.1438 44.reichmann jp, stevens pm, rheinstein j, kreulen cd. removable rigid dressings for postoperative management of transtibial amputations: a review of published evidence. pm & r. 2018;10(5):516-23. doi:10.1016/j.pmrj.2017.10.002 45.lee tg, chung s, chung yk. a retrospective review of iatrogenic skin and soft tissue injuries. arch plast surg. 2012;39(4):412-6. doi:10.5999/aps.2012.39.4.412 46.bandura a. health promotion by social cognitive means. health educ.behav.2004;31(2):143–64.doi:10.1177/1090198104263660 https://doi.org/10.33137/cpoj.v4i1.35098 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 research article altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.35206 1 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 research article effects of a prosthetic foot with increased coronal adaptability on crossslope walking altenburg b1*, ernst m1, maciejasz p2, schmalz t1, braatz f3, gerke h4, bellmann m1 1 research biomechanics, ottobock se & co. kgaa, göttingen, germany. 2 clinical research and services, ottobock se & co. kgaa, duderstadt, germany. 3 medical orthobionics, pivate university of applied sciences, göttingen, germany. 4 institute of biomechanics and orthopaedics, german sport university cologne, köln, germany. introduction real-life outdoor walking of persons with a lower limb amputation is continuously challenged by uneven ground, including bumps, obstacles, slopes and cross-slopes. cross-slopes are especially demanding,1 since many sidewalks are generally tilted for water drainage and often intersected with driveways. such tilted ground induces a functional leg length discrepancy, which is an apparent problem, in particular when the prosthetic limb is positioned hillside and is effectively too long. this requires the user to perform compensatory strategies during gait.2 conversely, an adaptive prosthesis may diminish compensatory user effort. in a lower limb prosthesis, the prosthetic foot is a open access volume 4, issue 1, article no.7. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: walking on cross-slopes is a common but challenging task for persons with lower limb amputation. the uneven ground and the resulting functional leg length discrepancy in this situation requires adaptability of both user and prosthesis. objective(s): this study investigated the effects of a novel prosthetic foot that offers adaptability on cross-slope surfaces, using instrumented gait analysis and patient-reported outcomes. moreover, the results were compared with two common prosthetic feet. methodology: twelve individuals with unilateral transtibial amputation and ten able-bodied control subjects participated in this randomized cross-over study. participants walked on level ground and ±10° inclined cross-slopes at a self-selected walking speed. there were three prosthetic foot interventions: triton side flex (tsf), triton lp and pro-flex lp. the accommodation time for each foot was at least 4 weeks. the main outcome measures were as follows: frontal plane adaptation of shoe and prosthetic foot keel, mediolateral course of the center of pressure, ground reaction force in vertical and mediolateral direction, external knee adduction moment, gait speed, stance phase duration, step length and step width. patient-reported outcomes assessed were the activities specific balanced confidence (abc) scale, prosthetic limb users survey of mobility (plus m) and activities of daily living questionnaire (adl-q). findings: the tsf prosthetic foot adapted both faster and to a greater extent to the cross-slope conditions compared to the triton lp and pro-flex lp. the graphs for the mediolateral center of pressure course and mediolateral ground reaction force showed a distinct grouping for level ground and ±10° cross-slopes, similar to control subjects. in the adl-q, participants reported a higher level of perceived safety and comfort when using the tsf on cross-slopes. eight out of twelve participants preferred the tsf over the reference. conclusion: the frontal plane adaptation characteristics of the tsf prosthetic foot appear to be beneficial to the user and thus may enhance locomotion on uneven ground – specifically on crossslopes. article info received: december 2, 2020 accepted: june 8, 2021 published: june 25, 2021 citation altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on crossslope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i 1.35206 keywords cross-slopes, transtibial, amputation, coronal adaptation, prosthetic foot, center of pressure, external knee adduction moment (ekam) * corresponding author björn altenburg, research biomechanics, ottobock se & co. kgaa, göttingen, germany. e-mail: bjoern.altenburg@ottobock.com orcid id: https://orcid.org/0000-0002-3484-4346 https://doi.org/10.33137/cpoj.v4i1.35206 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.35206 https://doi.org/10.33137/cpoj.v4i1.35206 https://doi.org/10.33137/cpoj.v4i1.35206 mailto:bjoern.altenburg@ottobock.com 2 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj central component which offers an individual adaptability, depending on the design and materials used.3 due to their carbon structure, common energy-storing-andreturning (esr) feet have a certain degree of flexibility, which allows for limited adaptation under load.3 it has been shown in different studies4-6 that a mechanical ankle joint can increase the range of motion in plantar and dorsiflexion and that a sophisticated microprocessor control can improve the adaptation to uneven ground.7-9 most studies have focused on adaptations in the sagittal plane. only a few studies have investigated prototype feet that adapt in the frontal plane.10,11 many esr feet are equipped with a split-toe feature that is thought to add flexibility in the frontal plane.3 however, it has not yet been shown that such foot design benefits individuals with lower-limb amputations walking on inclined ground. moreover, few studies have investigated amputees’ gait on cross-slopes.12-14 most recently, villa et al. revealed compensatory strategies of lower-limb amputees during prosthetic swing when the prosthesis was positioned hillside. individuals with transtibial amputation (ittas) showed increased hip and knee flexion in the residual limb for compensation and individuals with transfemoral amputation (itfas) increased hip hiking and vaulting.12 such vaulting strategies of itfas were investigated in a previous article by villa.13 starholm et al.14 found that itfas use significantly more energy when walking on a surface moderately tilted in the frontal plane compared to walking with a tilt in the sagittal plane. they assume that when the prosthesis is on the slope side it becomes functionally too long and provokes a more energy consuming gait pattern. the existing literature shows that the most-investigated situation of cross-slope walking of amputees is walking with the prosthesis hillside, whereby the focus is placed on prosthetic swing, intact side stance and required compensatory strategies. building on these approaches, this study focused on the biomechanics of the prosthetic stance phase in both crossslope conditions: foot positioned hillside (provokes eversion) and foot positioned valleyside (provokes inversion). the aim was to reveal the impact of the adaptability of the prosthetic foot on kinematics and kinetics of amputee gait on cross-slopes and to analyze the effects on balance and comfort by using self-reported outcome measures. the hypothesis was that a novel foot module with high frontal plane compliance enhances the locomotion of ittas on uneven ground. methodology participants twelve ittas participated in the study. this randomized cross-over study was approved by the ethics committee of the medical faculty of the university of göttingen, germany. inclusion criteria were as follows: active individuals (k-level 3, 4)15,16 with unilateral transtibial amputation, at least 18 months post-amputation, stable residual limb volume, stable gait pattern, aged 18 years or older. exclusion criteria were as follows: body weight exceeding 125 kg, any conditions that severely influence performance and gait like cardiovascular diseases or present socket issues. in addition, ten able-bodied individuals were included as controls. all participants provided written informed consent. prosthetic feet three esr feet were investigated (figure 1). the novel foot was the triton side flex (ottobock, germany). the tsf features a dedicated joint for frontal plane adaptations. this joint unit enables ±10° rotation (inversion/eversion) against a progressive resistance that is provided by a torsion bar.17 the rotational resistance increases towards the hard stop at 10° and is not user specific. the unit is screwed on a carbon base with split toes. the overall weight (size 27, including spectra sock and cosmetic cover) is 860 g. the build height (heel to top of the pyramid) is 109 mm. in addition, two reference feet were tested. the triton lp (ottobock, germany) contains the same carbon base as the tsf with matching properties in terms of dimensions and basic flexibility. the overall weight is 690 g and the build height 86 mm. the pro-flex lp (ossur, iceland) is a direct competitor of the triton lp in the section of low profile esr feet for active (k3 + k4) users. it features split toes as well, which are, however, asymmetrically designed. the overall weight (660 g) and build height (90 mm) are similar to the triton lp. workflow the study captured biomechanical data and patientreported outcomes. each participant tested the tsf and one reference foot. the selection of the reference foot and the order of tests (start with the tsf or reference) were randomized. all prosthetic assembling was done by the same certified prosthetist. the bench alignment followed the manufacturers’ specifications and was reproducibly done using a pros.a. assembly (ottobock, germany)18 followed by a static optimization19,20 on the l.a.s.a.r. posture (ottobock, germany)21 and a final dynamic optimization to the prosthetist’s and participants’ satisfaction. the accommodation time for each foot was at least 4 weeks prior to performing the biomechanical assessments and patient questionnaires. setup gait analysis measurements were gathered using a motion capture system consisting of 12 bonita cameras (vicon, uk, sampling rate 200 hz) and two force plates (kistler, switzerland, sampling rate 1000 hz). a dedicated marker set with 39 passive markers was applied. this enables the https://doi.org/10.33137/cpoj.v4i1.35206 https://shop.ottobock.ca/en/prosthetics/lower-limb-prosthetics/feet---mechanical/1c68-triton-side-flex/p/1c68 https://shop.ottobock.ca/en/prosthetics/lower-limb-prosthetics/feet---mechanical/1c63-triton-lp/p/1c63 https://www.ossur.com/en-gb/prosthetics/feet/pro-flex-lp 3 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj assessor to distinguish between the different contributions to the frontal plane adaptations of the foot including joint adaptation, carbon base deformation and shoe/foot shell deformation.3 for this purpose, the shoe and foot shell were modified and antenna markers were mounted directly on the carbon base (figure 1). during measurements, all participants wore the same model of shoe with defined marker positions. the studied situations were walking on level ground (using both force plates in the middle of the track) and walking on a 10° cross-slope, which was 8.5 m long and equipped with one force plate in the center. the participants were instructed to walk on the track at a self-selected, comfortable walking speed several times until eight valid recordings for each condition (level walking, four crossslope conditions: 10° prosthesis hillside, 10° intact side hillside, 10° prosthesis valleyside, 10° intact side valleyside) were captured. the inclusion or exclusion of each recording was determined by an assessor next to the track (inclusion criteria: steady state of walking in the middle of the track, entire foot on the force plate without obviously aiming for it and without specific step length adaptation). as the physical cross-slope setup remained the same for all cross-slope measurements, the starting point was adjusted for each individual subject and both walking directions were captured. for the healthy controls both sides were measured in equal distribution in order to generate comparative data in 3 different conditions (level, hillside, valleyside). in addition to the biomechanical measurements, participants completed a questionnaire evaluating amputees’ experience during 4 weeks or more of daily use. this questionnaire included the activities-specific balance confidence (abc) scale22 (16 questions), the prosthetic limb users survey of mobility (plus-m) scale23,24 (12-item short form) and a self-developed scale evaluating socket comfort and perceived safety in 40 situations of daily living (adl-scale). among the situations evaluated with the adlscale, there were 9 standing situations, 11 walking situations potentially affected by medial/lateral flexibility, 8 walking situations potentially unaffected by medial/lateral flexibility and 12 social activity situations. both socket comfort and perceived safety were measured on a numerical rating scale from 0 (worst) to 10 (best). at the end of the study, participants were also asked which of the two tested feet they preferred for daily use. data analysis valid trials were further processed with vicon nexus, customized vicon bodybuilder (vicon motion system, uk) and matlab (r2018a, mathwork inc, us) scripts. the following spatiotemporal gait characteristics were considered: gait speed, step length, step width and stance phase duration. the lateral shoe markers, figure 2 were used to automatically calculate these parameters with vicon nexus.25 furthermore, the following kinetic parameters were determined: ground reaction force in vertical (grfv) and mediolateral (grfml) direction; external knee adduction moment (ekam), considered as ekam peak (first maximum) and ekam impulse (ekam integral over duration of gait cycle (gc)). figure 1: experimental setup and prosthetic feet used. (a) shows the 8.5m cross-slope with a force plate embedded in the center of the track (shown step) and a typical participant (prosthesis is valleyside limb, intact side is hillside limb). (b) display the marker set for estimating the cop (markers on toe and heel of shoe) and the adaptation to the tilt (shoe markers and antenna markers through a cutout in the shoe and foot shell, attached to the carbon base). (c) shows the prosthetic feet tested: triton side flex (left), triton lp (middle) and pro-flex lp (right). a valleyside limb hillside limb b c https://doi.org/10.33137/cpoj.v4i1.35206 https://shop.ottobock.ca/en/prosthetics/lower-limb-prosthetics/feet---mechanical/1c68-triton-side-flex/p/1c68 https://shop.ottobock.ca/en/prosthetics/lower-limb-prosthetics/feet---mechanical/1c63-triton-lp/p/1c63 https://www.ossur.com/en-gb/prosthetics/feet/pro-flex-lp 4 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj the adaptation of the shoe and carbon base in the frontal plane and the mediolateral course of the center of pressure (cop) with respect to the foot were specific biomechanical parameters used in the study. the relative adaptation of the shoe in the frontal plane was determined in three steps. first, the angle between the projected connection line of medial and lateral shoe markers in the frontal plane and the horizontal surface was calculated (shoe in figure 2). second, the adaptation of the shoe was calculated: 'shoe=shoe+shank. hereby shank represents the frontal shank angle (shank in figure 2). third, the relative adaptation of the shoe in the frontal plane was calculated by subtracting the adaptations found for level walking from the adaptations found for cross-slope situations: αshoe='shoe,cross-slope 'shoe,level. the calculations were performed in the laboratory coordinate system. the same calculation was carried out for the medial / lateral antenna markers, which were attached to the associated parts of the carbon base (αbase). it was assumed that these values represent the adaptation of the carbon base of the prosthetic foot.3 the course of the cop was estimated, first, by projecting the cop of the force plate and the foot axis (defined by tip and heel marker on the shoe) to the surface and, second, by calculating the orthogonal distance of the projected cop to the projected marker line (copdist in figure 2). statistics for each situation, individual means (calculated from single trials) and group means (calculated from individual means) of the analyzed parameters were determined. to compare the effects of the different prosthetic foot types (reference feet vs. tsf) for certain setups (level, 10° hillside, 10° valleyside) a paired t-test was performed. if the assumed normal distribution (shapiro-wilks test) was not given, a non-parametric wilcoxon test was performed. to account for multiple testing, the alpha level was set to 1%. the statistical analysis was performed with ibm spss statistics (ibm corp., us). we did not conduct a statistical analysis of the effects of the cross-slopes angle within the groups, i.e. level vs 10° hillside vs 10° valleyside, nor did we consider a statistical comparison between ittas and control subjects. we did, however, perform a statistical analysis of the abc, plus-m and adl-scale scores. the adl scores were y y x z lateral medial lateral medial posterior anterior walking direction a b  shoe  base  shank figure 2: diagram to introduce the parameters used. (a) shank and foot from frontal view: markers, symbolized by circles, were projected in the frontal plane (y-z plane) to calculate shoe (medial and lateral shoe marker), base (medial and lateral antenna marker) and shank (virtual center of knee and ankle marker). these parameters were used to estimate the relative adaptation shoe and base to cross-slopes. the external knee adduction moment (ekam) was calculated using the virtual center of the knee (blue marker, middle of lateral and medial knee markers) and the ground reaction force (using cross product in lab coordinate system). (b) foot from transversal view (lab coordinate system): copdist, the orthogonal distance between the cop course (red-arrow line) and the foot axis (black-dashed line, defined by tip and heel marker), was calculated on the cross-slope surface. note, the cross-slope surface is tilted (10°) relative to the shown transversal plane (x-y plane) shown above. https://doi.org/10.33137/cpoj.v4i1.35206 5 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj separately determined for each activity block (standing, walking – non-m/l, walking – m/l, and social activities) and each dimension (safety, comfort) – resulting in eight adl scores per person and tested foot. the individual scores of participants obtained with different feet were compared using the paired t-test. results twelve ittas with activity level k3 (medicare functional classification level) or higher, participated in this study. further detailed demographic data are shown in table 1. in addition 10 control subjects (age: 29±7 years; weight: 83±15 kg; height: 183±11 cm) were also recruited for the study. the spatiotemporal parameters provided in table 2 showed no statistically significant differences between the tsf and reference feet for any condition. gait speed and step width tended to decrease from level to slope conditions for all feet. control subjects walked on average with higher gait speed, step length, and step width in all conditions (not statistically analyzed). the frontal plane adaptations of the studied feet and shoes in cross-slope conditions during stance are represented in figure 3. for the tsf, a major and continuous adaptation from the beginning of mid stance was found, whereas the reference feet showed only minor adaptations after loading response, constantly increasing with progressing stance. the amount of measured adaptation at mid stance (30% gc) was significantly (p<0.01) higher with the tsf compared to the reference feet in all slope conditions (table 3). the measured shoe adaptation showed similar characteristics with a smaller difference between the studied feet. the tsf reached the same amount of adaptation as the controls. the ekam impulse was significantly reduced for the valleyside condition with the tsf. no differences were found for hillside and level walking (table 3, figure 4). ekam peaks showed no differences in all conditions. control subjects presented notably higher values of peak ekam in all conditions. the cop paths of the control subjects showed a medial shift when the foot in question was positioned valleyside, but a close grouping for the hillside position and level walking. the tsf produced a similar grouping for level and hillside conditions, but a lateral shift for the valleyside condition. esr feet revealed a different cop path pattern with a distinct laterally shifted curve for the hillside and a medially shifted curve for the valleyside condition. a comparison of esr and tsf feet demonstrated significantly different cop paths for all conditions (table 3). grfv showed no differences between the feet in all conditions. there was a trend towards an increased first maximum for the valleyside condition. grfml differed significantly between the investigated feet in the valleyside condition (30% gc). the results of the patient-reported outcomes are shown in table 4. they found significantly (p<0.05) higher ratings for the tsf foot for perceived comfort while standing and perceived comfort and safety while walking in situations potentially affected by medial/lateral flexibility (adl scale). all other adl sub-scales, as well as abc and plus-m, tended towards higher ratings when using the tsf foot, but did not attain statistical significance. as far as foot preference was concerned, eight participants preferred the tsf, three participants preferred one of the reference feet (1x triton lp, 2x pro-flex lp), and one participant had no preference. participant age weight (kg) height (m) gender k-level socket suspension foot #1 foot #2 s01 51 69 1,83 m 3 suction, one way valve tsf triton lp s02 61 125 1,80 m 3 soft socket, supracondylar tsf pro-flex lp s03 38 88 1,68 m 4 suction, one way valve pro-flex lp tsf s04 77 86 1,75 m 3 pin lock tsf pro-flex lp s05 47 50 1,56 w 3 suction, one way valve pro-flex lp tsf s06 59 86 1,78 m 3 suction, one way valve tsf pro-flex lp s07 44 68 1,68 w 3 suction, one way valve triton lp tsf s08 52 78 1,77 m 3 suction, one way valve tsf triton lp s09 37 90 1,84 m 3 suction, one way valve triton lp tsf s10 64 99 1,88 m 3 suction, one way valve triton lp tsf s11 57 79 1,80 m 4 suction, one way valve pro-flex lp tsf s12 47 97 1,83 m 4 pin lock tsf triton lp mean 52,8 83,9 1,77 sd 11,5 19,4 0,09 range 37-77 50-125 1,56-1,88 table 1: demographic data of study participants with transtibial amputation and allocated prosthetic feet (randomized process). https://doi.org/10.33137/cpoj.v4i1.35206 6 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj table 2: spatiotemporal parameters of the tsf and reference feet for level walking and 10° cross-slope conditions. no statistically significant differences between foot types were found (p<0.01) prosthetic foot condition gait velocity (m/s) step length (m) stance phase duration (% gc) step width (m) tsf level 1.27 ± 0.12 0.74 ± 0.05 60.7 ± 1.3 0.22 ± 0.03 10° hillside 1.25 ± 0.14 0.75 ± 0.05 61.1 ± 1.2 0.21 ± 0.03 10° valleyside 1.23 ± 0.13 0.71 ± 0.05 60.3 ± 1.3 0.20 ± 0.02 reference level 1.27 ± 0.14 0.73 ± 0.06 61.3 ± 0.9 0.22 ± 0.02 10° hillside 1.24 ±0.14 0.75 ± 0.06 61.1 ± 1.4 0.21 ± 0.02 10° valleyside 1.25 ± 0.15 0.72 ± 0.07 60.7 ± 1.2 0.20 ± 0.03 controls level 1.44 ± 0.15 0.79 ± 0.09 61.7 ± 1.1 0.27 ± 0.03 10° hillside 1.42 ± 0.19 0.79 ± 0.08 61.8 ± 1.4 0.25 ± 0.04 10° valleyside 1.43 ± 0.19 0.77 ± 0.08 60.8 ± 1.4 0.26 ± 0.03 table 3: parameters of the prosthetic side for the different setups at the first maximum peak (grfv, ekam peak), whole gc (ekam impulse) and at 30% gc (grfml, αbase, αshoe, copdist). statistically significant differences between foot types are marked bold (p<0.01) or bold and * (p<0.001). parameter grfv (%bw) grfml (%bw) αbase (deg) αshoe (deg) copdist (mm) ekam peak (nm/kg) ekam impulse (nm/kg*s) level tsf 108 ± 11 4.4 ± 1.3 9 ± 5 0.34 ± 0.12 0.09 ± 0.04 level reference feet 108 ± 7 4.5 ± 1.2 14 ± 7 0.32 ± 0.11 0.09 ± 0.04 level controls 111 ± 5 2.0 ± 0.8 9 ± 6 0.49 ± 0.10 0.19 ± 0.05 hillside tsf 108 ± 13 4.2 ± 1.3 -8.8 ± 1.6 * -11.9 ± 0.8 13 ± 5 * 0.27 ± 0.13 0.08 ± 0.04 hillside reference feet 109 ± 12 4.5 ± 1.1 -2.1 ± 0.6 * -10.7 ± 0.8 24 ± 5 * 0.26 ± 0.13 0.08 ± 0.04 hillside controls 107 ± 6 2.2 ± 0.8 -12.0 ± 0.9 10 ± 7 0.38 ± 0.10 0.16 ± 0.06 valleyside tsf 112 ± 12 3.4 ± 1.5 7.9 ± 1.8 * 11.9 ± 2.0 13 ± 6 * 0.38 ± 0.14 0.11 ± 0.03 valleyside reference feet 112 ± 11 2.4 ± 1.2 2.9 ± 1.0 * 10.6 ± 1.2 2 ± 5 * 0.40 ± 0.12 0.14 ± 0.03 valleyside controls 112 ± 7 1.2 ± 0.7 12.0 ± 1.0 5 ± 6 0.56 ± 0.16 0.22 ± 0.06 table 4: summary of the scores in the patient-reported outcomes for reference feet and the tsf. significant differences in a parameter are marked bold for the p values (p<0.05). analyzed parameter: n reference feet (mean ± sd) tsf (mean ± sd) p abc (balance confidence) 12 86.6 ± 8.6 89.2 ± 8.4 0.14 plus-m (mobility) 12 56.6 ± 7.3 57.3 ± 7.8 0.67 adl: standing situations (9 questions) perceived comfort 12 8.4 ± 1.0 9.1 ± 0.8 0.02 perceived safety 12 8.8 ± 0.8 9.2 ± 0.7 0.11 adl: walking in situations potentially affected by the medial/lateral flexibility (11 questions) perceived comfort 12 8.3 ± 1.1 8.9 ± 0.8 0.02 perceived safety 12 8.4 ± 1.1 9.0 ± 0.9 0.04 adl: walking in situations potentially not affected by the medial/lateral flexibility (8 questions) perceived comfort 12 8.3 ± 0.9 8.8 ± 0.8 0.11 perceived safety 12 8.4 ± 1.0 8.7 ± 1.0 0.34 adl: social activities (12 questions) perceived comfort 12 8.3 ± 1.0 8.9 ± 0.8 0.05 perceived safety 12 8.6 ± 0.9 8.9 ± 0.9 0.12 https://doi.org/10.33137/cpoj.v4i1.35206 7 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj discussion the aim of this study was to investigate the effects of a novel prosthetic foot, with adaptability on cross-slope surfaces, using instrumented gait analysis and patientreported outcomes. several results support the initial hypothesis that a foot module with easily accessible frontal plane adaptation can enhance locomotion on uneven ground. first, the early and extensive adaptation at the beginning of stance found in this study appears to be of importance and agrees with the findings of yeates10 who suggested an improved balance on uneven ground derived from greater frontal adaptation in early stance. here the tsf adapts both earlier (at loading response, 10% gc) and more extensively and keeps this adaptation until the end of stance (figure 3). the users felt directly a different foot behavior when stepping on the crossslope and reported a higher level of perceived safety. with the common esr split toe concept of the measured reference feet, the maximum adaptation occurs at the end of stance with maximum toe load. the absolute value of adaptation is not exactly known since the measured position of the antenna markers fixed on the carbon base always reflect a combined adaptation of rotation of the carbon base, toe shift and toe twist.3 nevertheless, the timing of adaptation is not affected. the frontal plane adaptation of the shoes reveals similar characteristics as the carbon bases with constant values for the tsf, but increasing adaptation as stance progresses for standard esr feet. however, the difference in adaptation is smaller compared to the carbon base data. this suggests movement, like tilt between carbon base, foot cover and shoe, that is usually not detected with conventional marker placement on the shoes. consequently, every shoe as well as every prosthetic foot cover contributes to the overall adaptation. the data for shoe adaptation shows an overshoot in value for the tsf and control subjects (12° value on a 10° crossslope). load-dependent shoe-sole compression and a different shank orientation (by leaning to a side) when walking on cross-slopes are plausible reasons for this effect. the ekam is a clinically relevant parameter, since its first peak has been positively associated with medial compartment knee osteoarthritis (oa).26-29 the ekam impulse is also commonly studied in conjunction with oa2932 according to chang et al.33, it might even be the more comprehensive indicator of cumulative medial compartment loading during gait. this study showed a significantly reduced ekam impulse for the valleyside condition using the tsf, but no differences in ekam peak (table 3, figure 4a). however, compared to the clearly higher moments generated by the control subjects, the overall impact on oa risk appears negligible. still, this effect of prosthetic side knee load reduction for valleyside conditions might increase in similar everyday life loading scenarios with higher gait speed or varying step width.34 in general, the clearly higher gait speed and wider step width of the control subjects has to be considered when comparing absolute knee loading. tsf reference feet e v e rs io n in v e rs io n time [% gait cycle] time [% gait cycle] r e la ti v e f ro n ta l a d a p ta ti o n [° ] 0 10 20 30 40 50 60 0 10 20 30 40 50 60 -15 -10 -5 0 10 15 5 figure 3: relative frontal adaptation on the cross-slope for triton side flex (left) and reference feet (right) for 10% to 50% gc (main loading interval). the solid red (hillside) and solid blue (valleyside) curves show the adaptation of the prosthesis via the antenna markers (αbase). the grey (control subjects) and dashed (prosthetic side) curves show the adaptation determined by the markers on the shoes (βshoe). https://doi.org/10.33137/cpoj.v4i1.35206 8 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj a b c d tsf reference feet controls varus valgus lateral medial medial lateral time [% gait cycle] time [% gait cycle] time [% gait cycle] 0 10 20 30 40 50 60 0 10 20 30 40 50 60 0 10 20 30 40 50 60 0 20 40 60 80 100 120 g r f v [ % b w ] -8 -6 -4 -2 0 2 4 6 8 g r f m l [% b w ] -10 -5 0 5 10 15 20 25 c o p d is t [ m m ] e k a m [ n m /k g ] -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 figure 4: parameters for the different studied situations. (a) ekam, (b) mediolateral cop course, (c) mediolateral ground reaction forces and (d) vertical ground reaction forces. the left column shows the prosthetic side values for the reference feet, the middle column the prosthetic side values for the tsf foot and the right column show the control subjects. the blue curves indicate the valleyside situations, the red curves indicate the hillside situations and the black curves indicate level walking. the associated standard deviations are given as shared areas for the blue and red curves. https://doi.org/10.33137/cpoj.v4i1.35206 9 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj the cop path shows clear foot-dependent differences (figure 4b). it can be assumed that the additional joint of the tsf quickly adapts, similar to the subtalar joint of the control subjects, causing similarly grouped cop paths for the tsf and control subjects. the limited adaptation capability of the low profile esr feet forces a main load transfer towards the lateral rim of the foot base (hillside condition) or towards the medial rim (valleyside condition), respectively, causing clearly different cop paths compared to the level walking condition. the authors assume that these deviations require more compensatory strategies by the user to safely walking on cross-slopes. the grfml also showed a close grouping for the tsf and control subjects (figure 4c). this effect might facilitate more predictable steps with less control effort on cross-sloped surfaces or similar terrain. for the hillside conditions, there were no foot-dependent differences found for ekam and grfml, despite clear differences in frontal plane adaptation, cop paths and reported advantages while using the tsf. it can be assumed that the functional leg length discrepancy (35 mm longer prosthetic side on 10° cross-slope, 20 cm step width) is a major problem to overcome for the user that presumably requires higher control and energetic efforts. according to walsh et al.,2 leg length discrepancies greater than 5 mm require compensatory strategies during gait. the additional joint in the tsf allows for an effective shortening of about 5 mm in this condition which is a small proportion of the estimated 35 mm leg length discrepancy but seems to positively impact perceived comfort and safety. still, it did not translate into the measured parameters ekam and grfml. the patient-reported outcomes favored the tsf. however, it is noticeable that all ratings were found to be close to the maximum scores of the scales with relatively small differences between the feet tested. it has to be considered that all participants were active ambulators with highly functional components in their current prostheses and did not report major limitations in their everyday lives. they were all considered high-functioning, safe walkers. nevertheless, statistically significant differences were found in 3 scales. it is believed that the increased perceived safety of the tsf is based on the fast adaptation at low loading and the resulting consistent grfml (figure 4c) on sloped surfaces. the reduced control effort may lead to diminished movement in the residual limb-socket interface and could be the reason for the increased perceived comfort. the preference question at the end of the study revealed, on the one hand, a clear preference by 8 of the 12 participants for the tsf. on the other hand, interesting arguments for its rejection were offered by the other participants. two participants preferred the pro-flex lp because it was perceived to provide a more comfortable rollover. one participant preferred the triton lp since he had an unstable knee and could not stabilize it in the frontal plane when using the tsf. this may hint at a possible contraindication for fitting such adaptive foot components that warrants further study. study limitations due to the long accommodation time (at least 4 weeks) for the test prosthesis, a blinding of the foot condition was not practicable, which introduced a potential bias in favor of the novel foot (expectation). the use of two different reference feet and grouping them into one reference is a limitation in methodology since it is to be assumed that both reference feet do not perform identically. the healthy control population was not an exact match to the experimental population in terms of age. this may impact gait characteristics. conclusion this is the first study analyzing prosthetic side loading during cross-slope walking of individuals with transtibial amputation which has provided new quantitative results. although the obvious problem of a functional leg length discrepancy during cross-slope walking cannot entirely be solved by the novel foot studied, the results suggest an improved frontal plane adaptability of the prosthetic foot. in particular a comprehensive adaptation starting at low loading in early stance may enhance locomotion on crossslopes such as uneven ground. acknowledgements we would like to thank the anonymous reviewers for their valuable and constructive feedback. declaration of conflicting interests mr. björn altenburg, dr. michael ernst, dr. pawel maciejasz, dr. thomas schmalz and dr. malte bellmann are full time employees of ottobock se & co. kgaa. author contribution • björn altenburg: study design, prosthetic fittings, gait lab measurements, data interpretation, draft manuscript. • michael ernst: gait lab measurements, biomechanical data analysis, data interpretation, draft manuscript. • pawel maciejasz: preparation, evaluation and analysis of the outcome measurements. • thomas schmalz: supervision, revise manuscript. • frank braatz: supervision, revise manuscript. • henrik gerke: gait lab measurements, biomechanical data analysis. https://doi.org/10.33137/cpoj.v4i1.35206 10 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj • malte bellmann: study design, supervision, data interpretation, revise manuscript. sources of support none. ethical approval this randomized cross-over study was approved by the ethics committee of the medical faculty of the university of göttingen, germany. all participants provided written informed consent. references 1.kockelmann k, zhao y, blanchard-zimmermann c. meeting the intent of ada in sidewalk cross-slope design. j rehabil res dev. 2001;38(1):101-10. 2.walsh m, connolly p, jenkinson a, o’brien t. leg length discrepancy – an experimental study of compensatory changes in three dimensions using gait analysis. gait posture 2000;12:156-61. doi: 10.1016/s0966-6362(00)00067-9 3.ernst m, altenburg b, schmalz t, characterizing adaptations of prosthetic feet in the frontal plane. prosth orthot int. 2020; 44,4, 225-233. doi: 10.1177/0309364620917838 4.ferris ae, aldridge jm, rábago ca, wilken jm. evaluation of a powered ankle-foot prosthetic system during walking. arch phys med rehabil. 2012; 93 (11): 1911-8. doi: 10.1016/j.apmr. 2012.06.009 5.schlafly m, reed kb. novel passive ankle-foot prosthesis mimics able-bodied ankle angles and ground reaction forces. clin biomech 2019;72:202-210. doi: 10.1016/j.clinbiomech.2019.12.016 6.heitzmann dww, salami f, de asha ar, block j, putz c, wolf si, alimusaj m. benefits of an increased prosthetic ankle range of motion for individuals with a trans-tibial amputation walking with a new prosthetic foot. gait posture. 2018; 64:174-180. doi: 10.1016/j.gaitpost.2018.06.022 7.schmalz t, altenburg b, ernst m, bellmann m, rosenbaum d. lower limb amputee gait characteristics on a specifically designed test ramp: preliminary results of a biomechanical comparison of two prosthetic foot concepts. gait posture. 2019;68:161-167. doi: 10.1016/j.gaitpost.2018.11.017 8.ernst m, altenburg b, bellmann m, schmalz t. standing on slopes how current microprocessor-controlled prosthetic feet support transtibial and transfemoral amputees in an everyday task. j neuroeng rehabil. 2017;14(1):117. doi: 10.1186/s12984-0170322-2. 9.thomas-pohl m, villa c, davot j, bonnet x, facione j, lapeyre e, bascou j, pillet h. microprocessor prosthetic ankles: comparative biomechanical evaluation of people with transtibial traumatic amputation during standing on level ground and slope. disabil rehabil assist technol. 2019;19:1-10. doi: 10.1080/17483107.2019.1629112. 10.yeates kh, segal ad, neptune rr, klute gk. a coronally clutching ankle to improve amputee balance on coronally uneven and unpredictable terrain. j med devices. 2018; 12(3): 031001. doi:10.1115/1.4040183 11.collins sh, kim m, chen t, chen t. an ankle-foot prosthesis emulator with control of plantarflexion and inversion-eversion torque. ieee int conf robot autom. 2015; 1210-1216, doi: 10.1109/icra.2015.7139345 12.villa c, loiret i, langlois k, bonnet x, lavaste f, fodé p, et al. cross-slope and level walking strategies during swing in individuals with lower limb amputation. arch phys med rehabil. 2017; 98: 1149. doi: 10.1016/j.apmr.2016.10.007 13.villa c, drevelle x, bonnet x, lavaste f, loiret i, fodé p, et al. evolution of vaulting strategy during locomotion of individuals with transfemoral amputation on slopes and cross-slopes compared to level walking. clin biomech. 2015;30:623-8. doi: 10.1016/ j.clinbiomech.2015.03.022 14.starholm i-m, gjovaag t, mengshoel am. energy expenditure of transfemoral amputees walking on a horizontal and tilted treadmill simulating different outdoor walking conditions. prosthet orthot int. 2010; 34: 184–194, doi:10.3109/03093640903585016 15.gailey rs, roach ke, applegate eb, cho b, cunniffe b, licht s, et al. the amputee mobility predictor: an instrument to assess determinants of the lower-limb amputee’s ability to ambulate. arch phys med rehabil. 2002;83:613-27. doi: 10.1053/ampr.2002.32309 16.orendurff ms, raschke su, winder l, moe d, boone da, kobayashi t. functional level assessment of individuals with transtibial limb loss: evaluation in the clinical setting versus objective community ambulatory activity. j rehabil assist technol eng. 2016; 2055668316636316. doi:10.1177/2055668316636316 17.ottobock feet mechanical [internet]; triton side flex 3d animation video [cited 2021 may 14]. available from: https://shop.ottobock.us/prosthetics/lower-limb-prosthetics/feet--mechanical/1c68-triton-side-flex/p/1c68 18.ottobock planning & equipping, materials [internet]; pros.a assembly [cited 2021 may 14]. available from: https://pe.ottobock.com/en/ot/products/743a220-prosaassembly.html 19.blumentritt s, schmalz t, jarasch r, schneider m. effects of sagittal plane prosthetic alignment on standing trans-tibial amputee knee loads. prosthet orthot int. 1999;23(3):231-8. doi:10.3109/ 03093649909071639 20.blumentritt s, schmalz t, jarasch r. significance of static prosthesis alignment for standing and walking of patients with lower limb amputation. orthopade. 2001;30(3):161-8. doi:10.1007/ s001320050590 21.blumentritt s, a new biomechanical method for determination of static prosthetic alignment. prosthet orthot int. 1997; 21, 107-13. doi: 10.3109/03093649709164538 22.powell le, myers am. the activities-specific balance confidence (abc) scale. j gerontol a biol sci med sci. 1995;50(1):m28-34. doi:10.1093/gerona/50a.1.m28 23.hafner bj, morgan sj, abrahamson dc, amtmann d. characterizing mobility from the prosthetic limb user's perspective: use of focus groups to guide development of the prosthetic limb users survey of mobility. prosthet orthot int. 2016;40(5):582-90. doi: 10.1177/0309364615579315 https://doi.org/10.33137/cpoj.v4i1.35206 11 altenburg b, ernst m, maciejasz p, schmalz t, braatz f, gerke h, bellmann m. effects of a prosthetic foot with increased coronal adaptability on cross-slope walking. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.7. https://doi.org/10.33137/cpoj.v4i1.35206 issn: 2561-987x effects of prosthetic foot on cross-slope walking altenburg et al. 2021 cpoj 24.hafner bj, gaunaurd ia, morgan sj, amtmann d, salem r, gailey rs. construct validity of the prosthetic limb users survey of mobility (plus-m) in adults with lower limb amputation. arch phys med rehabil. 2017; 98(2):277-85 doi: 10.1016/j.apmr. 2016.07.026. 25.vicon nexus product guide, manual [internet]; [cited 2021 march 1], available from: https://documentation.vicon.com/nexus/v2.2/nexus1_8guide.pdf 26.baliunas aj, hurwitz de, ryals ab, karrar a, case jp, block ja, et al. increased knee joint loads during walking are present in subjects with knee osteoarthritis. osteoarthr. cartil. 2002;10(7): 573-579. doi: 10.1053/joca.2002.0797 27.mündermann a, dyrby co, hurwitz de, sharma l, andriacchi tp. potential strategies to reduce medial compartment loading in patients with knee osteoarthritis of varying severity: reduced walking speed. arthritis rheum. 2004; 50:1172-1178. doi: 10.1002/art.20132 28.miyazaki t, wada m, kawahara h, sato m, baba h, shimada s. dynamic load at baseline can predict radiographic disease progression in medial compartment knee osteoarthritis. ann rheum dis. 2002; 61:617-622. doi: 10.1136/ard.61.7.617 29.thorp le, sumner dr, wimmer ma, block ja. relationship between pain and medial knee joint loading in mild radiographic knee osteoarthrithis. arthitis rheum. 2007; 57:1254-126031. doi: 10.1002/art.22991 30.creaby mw, wang y, bennell kl, hinman rs, metcalf br, bowles ka, et al. dynamic knee loading is related to cartilage defects and tibial plateau bone area in medial knee osteoarthritis. osteoarthr. cartil. 2010;18:1380–1388. doi: 10.1016/j.joca. 2010.08.013 31.bennell kl, bowles ka, wang y, cicuttini f, davies-tuck m, et al. higher dynamic medial knee load predicts greater cartilage loss over 12 months in medial knee osteoarthritis. ann rheum dis.2011; 70:1770–1774. doi: 10.1136/ard.2010.147082 32.kito n, shinkoda k, yamasaki t, kanemura n, anan m, okanishi n, et al. contribution of knee adduction moment impulse to pain and disability in japanese women with medial knee osteoarthritis. clin biomech. 2010; 25:914–919. doi: 10.1016/j.clinbiomech.2010.06.008 33.chang ah, moisio kc, chmiel js, eckstein f, guermazi a, prasad pv, et al. external knee adduction and flexion moments during gait and medial tibiofemoral disease progression in knee osteoarthritis. osteoarthr. cartil. 2015;23(7):1099-106. doi: 10.1016/j.joca.2015.02.005 34.favre j, erhart-hledik jc, chehab ef, andriacchi tp. general scheme to reduce the knee adduction moment by modifying a combination of gait variables. j orthop res. 2016;34(9):1547-56. doi: 10.1002/jor.23151. https://doi.org/10.33137/cpoj.v4i1.35206 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 research article frengopoulos c, zia z, payne m.w.c, viana r, hunter s.w. association between balance self-efficacy and walking ability in those with new lower limb amputations. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.4. https://doi.org/10.33137/cpoj.v5i1.36695 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.36695 1 frengopoulos c, zia z, payne m.w.c, viana r, hunter s.w. association between balance self-efficacy and walking ability in those with new lower limb amputations. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.4. https://doi.org/10.33137/cpoj.v5i1.36695 research article association between balance self-efficacy and walking ability in those with new lower limb amputations frengopoulos c 1*, zia z 2, payne m.w.c 3, 4, viana r 3, 4, hunter s.w 1,4, 5 1 faculty of health sciences, university of western ontario, london, ontario, canada. 2 michael g. degroote school of medicine, mcmaster university, london, ontario, canada. 3 department of physical medicine & rehabilitation, parkwood institute, london, ontario, canada. 4 department of physical medicine & rehabilitation, schulich school of medicine & dentistry, university of western ontario, london, ontario, canada. 5 school of physical therapy, university of western ontario, london, ontario, canada. introduction individuals encounter significant physical, psychological and social consequences following the loss of a limb.1 while the physical concerns of decreased mobility are paramount, there are also difficulties with community participation and body image that requires attention.2 rehabilitation for lower limb amputation (lla) is multidisciplinary and goals include restoring independent mobility and enhancing quality of life (qol).3 performance on objective measures of mobility is often considered to be the gold standard for evaluating rehabilitation progress or success.4 however, subjective assessments can also be considered as they may provide insight for perceived mobility in scenarios not tested in clinical environment. there is an established trend in open access volume 5, issue 1, article no.4. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: a relationship between walking ability and self-efficacy has been demonstrated in various rehabilitation patient populations. in experienced prosthetic ambulators, walking ability is related to self-efficacy of balance, however, this relationship has not been quantified for those with newly acquired lower limb amputations (lla). objective(s): to investigate the association between walking performance (objective) and selfreported walking abilities (subjective) on balance self-efficacy in those with lla. methodology: cross-sectional study of 27 people (17 men; mean age=63.57±9.33) at discharge from inpatient prosthetic rehabilitation for first major unilateral lla. individuals completed 6m straight path walking and the l-test under singleand dual-task conditions. the prosthesis evaluation questionnaire (peq) was administered, and the ambulation subscale provided subjective measures of walking ability. a single peq question on satisfaction with walking (16b) was also used as a proxy for subjective walking ability. the activities-specific balance confidence scale measured balance selfefficacy. multivariable linear regression was used to evaluate the strength of association between walking ability (objective and subjective) and balance self-efficacy (dependent variable). findings: walking velocity on the 6m straight path under single-task (p=0.011) and dual-task conditions (p=0.039), the single-task l-test (p=0.035) and self-reported satisfaction with walking (p=0.019) were associated with self-efficacy of balance. conclusion: objective measures of walking ability that were independently associated with balance self-efficacy included straight path walking velocity under single and dual-task conditions and the singletask l-test. satisfaction with walking was also associated with balance self-efficacy. this highlights the interplay between physical and psychological factors during rehabilitation. more research in the area of self-efficacy and walking ability is needed to establish self-efficacy as a target during prosthetic rehabilitation for those with lla. article info received: august 8, 2021 accepted: january 2, 2022 published: january 11, 2022 citation frengopoulos c, zia z, payne m.w.c, viana r, hunter s.w. association between balance selfefficacy and walking ability in those with new lower limb amputations. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.4. https://doi.org/10.33137/cpoj.v5i1.3 6695 keywords amputation, self-efficacy, balance confidence, walking ability, rehabilitation, peq * corresponding author courtney frengopoulos, university of western ontario, room 1408, elborn college, london, ontario, canada, n6g 1h1. email: cfrengop@uwo.ca orcid id: https://orcid.org/0000-0002-4131-2727 https://doi.org/10.33137/cpoj.v5i1.36695 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i1.36695 https://doi.org/10.33137/cpoj.v5i1.36695 mailto:cfrengop@uwo.ca https://orcid.org/0000-0002-4131-2727 2 frengopoulos c, zia z, payne m.w.c, viana r, hunter s.w. association between balance self-efficacy and walking ability in those with new lower limb amputations. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.4. https://doi.org/10.33137/cpoj.v5i1.36695 issn: 2561-987x association between balance self-efficacy and walking ability frengopoulos et al., 2022 cpoj walking ability following prosthetic rehabilitation for lla; the largest improvements in self-reported functional mobility occur between 6 weeks and 4 months post-surgery, after which time function plateaus.5 while mobility and function improve during rehabilitation, the lla population may experience difficulties with gait that persist long-term.6,7 falls are a particular concern in this population, as over half of those with lla fall at least once annually.8,9 after a fall, older individuals without lla may limit their walking due to impact on self-efficacy and a fear of falling.9 however, walking is crucial for social participation and maintaining qol in those with lla.10 as such, the impact of psychological factors on walking ability in this population have been investigated. research indicates that factors such as self-efficacy may impact upon the rehabilitation goals of social activity and community integration for those with lla.11,12 self-efficacy is an individual’s belief in their ability to perform a certain task.13 developing self-efficacy may be done through observing successful peers or through verbal persuasion from credible individuals, such as physicians.13,14 however, the strongest sources of selfefficacy are mastery experiences; other sources are generally weak and are likely to deteriorate.14,15 mastery experiences are the successful completion of a specific task.15 these experiences can build upon each other as an individual accomplishes progressively more difficult activities.15 as such, the mastery experience of ambulating with a prosthetic device would be expected to strongly impact a person’s sense of competence and self-efficacy. research has demonstrated a positive relationship between walking performance and self-efficacy following a stroke,16 in those with knee osteoarthritis,17,18 for those with diabetes and peripheral arterial disease,19 and in individuals with multiple sclerosis.20 however, the experience following lla is different to these populations as the latter have previous mastery experiences from which they derive their selfefficacy. at the onset of rehabilitation, all tasks relating to the prosthetic device are novel. prosthetic training provides a series of mastery experiences for new skills related to the use of a prosthesis, allowing those with lla to develop selfefficacy. individuals also receive encouragement from clinicians during their time in prosthetic rehabilitation and are able to observe fellow patients. levels of self-efficacy during this rehabilitation process have not been reported, however, for more experienced prosthetic ambulators, walking ability is related to balance self-efficacy.12 physical and psychological factors are both important considerations for rehabilitation following lla. for the psychological factor of self-efficacy to be addressed as a target during the rehabilitation process, a better understanding of the relationship between walking ability and self-efficacy is needed. to quantify the relationship between self-efficacy of balance and walking ability in those with lla, self-reported measures of ability and objective walking performance must be carried out. the objective of this study was to investigate the association between walking performance (objective) and self-reported walking ability (subjective) on balance self-efficacy in those with lla at discharge from inpatient prosthetic rehabilitation. it is hypothesized that at this stage in the rehabilitation process straight path walking and complex path walking under single-task conditions, as well as patient satisfaction with walking, will be related to balance self-efficacy. methodology design and participants this was a cross-sectional study of individuals completing inpatient prosthetic rehabilitation for first major lla. participants were recruited from the regional amputee rehabilitation program at parkwood institute in london, ontario between march 2016 and april 2017. the study was approved by the university of western ontario ethics board, and by the lawson health research institute clinical resources impact committee. all individuals provided written informed consent prior to participating in the study. individuals participating in an inpatient rehabilitation program for their first major, unilateral lla were recruited prior to discharge. lla at the level of transtibial or above were considered major amputations; these were selected as the represent the most common levels seen in prosthetic rehabilitation programs. all individuals were new prosthetic ambulators as they were fitted with a prosthesis upon commencement of inpatient rehabilitation. admission criteria to inpatient rehabilitation include achievable rehabilitation and prosthetic goals, medically stable and sufficiently conditioned to undergo a training program, ability to learn and retain new skills, and emotionally and socially (housing, funding, outside responsibilities, etc.) prepared to participate. training involved prosthetic limb fitting, limb care and management, and safe skill learning to progress from transfers to gait training with the use of various gait aids. eligibility criteria for the current study were: ≥50 years of age, functional use of english and ability to walk 10m without assistance from another person. exclusion criteria included any physical problem that significantly limited movement or presence of severe depression. those were severe depression were excluded as depression can negatively impact performance on cognitive tasks requiring attention and visuospatial abilities, especially in older adults.21 a total of 27 participants were recruited during the study period. the following demographic and medical history information was obtained: age, sex, height, weight, level of amputation, etiology of amputation, time since amputation, use of walking aid at discharge, level of education, medications, https://doi.org/10.33137/cpoj.v5i1.36695 3 frengopoulos c, zia z, payne m.w.c, viana r, hunter s.w. association between balance self-efficacy and walking ability in those with new lower limb amputations. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.4. https://doi.org/10.33137/cpoj.v5i1.36695 issn: 2561-987x association between balance self-efficacy and walking ability frengopoulos et al., 2022 cpoj comorbidities, history of falls in the past 12 months, global cognitive status as measured by the montreal cognitive assessment (moca). objective measures of walking ability the l-test is a complex walking task that evaluates functional mobility for those with lla.22 testing was carried out under singleand dual-task conditions with standardized instructions.22,23 using standard instructions, participants began sitting on an armless chair and upon the word “go” rose to standing and walked 3 meters, turned 90 degrees, walked 7 meters, turned 180 degrees, and walked the same path to return to a seated position. patients walked at their usual pace and were timed to the nearest 100th of a second. a 6m straight path assessed gait velocity (cm/s) under singleand dual-task conditions. participants walked at their usual pace along the gaitrite® system electronic walkway (cir systems, franklin, nj). one-meter acceleration and deceleration zones were provided to ensure only steady state walking was captured. assessment of gait velocity using the gaitrite® system was performed separately to the walking assessment using the l-test. subjective measures of walking ability the prosthesis evaluation questionnaire (peq) is a selfadministered tool that evaluates prosthetic related qol.24 it consists of 9 stand-alone subscales including ambulation, appearance, frustration, perceived response, residual limb health, social burden, sounds, utility and well being. the ambulation subscale was used to assess selfperceived walking ability (questions 13a, 13b, 13c, 13d, 14e, 14f, 14g, 14h).24 the following standalone question relating to participant satisfaction (question 16b) was also used: “over the past four weeks, rate how satisfied you have been with how you are walking”. questions utilize a 100mm visual analog scale (vas) from “cannot” (0) to “no problem” (100). higher scores indicate a more positive response.24 the complete peq was administered to participants. measure of balance self-efficacy the abc scale is a 16-item tool that evaluates balance confidence, or self-efficacy of balance.25 participants rate how confident they are in performing activities without losing their balance or becoming unsteady, from 0% to 100%. a mean of the 16 items gives the overall score, with higher scores indicating better balance self-efficacy.25 the scale has good test-retest reliability and internal consistency in the lla population.26 testing protocol single-task (walking test alone) and dual-task (walking task paired with cognitively demanding task) walking assessments were performed in this study. demographic and clinical information was collected first. following this, walking tasks were demonstrated by a research assistant. participants then completed single-task assessments and received a 5-minute break before completing dual-task testing. only one trial per walking test was completed. dualtask testing using a cognitively demanding task was used to more closely approximate real-world walking.27 the task chosen to represent this increased cognitive load was serial subtraction by 3’s, starting from a randomly selected number between 100 and 150. participants were instructed to count aloud as they walked, and responses were recorded. no instructions on task prioritization were given. all assessments occurred within 48 hours of discharge. patients used their usual gait aids to perform walking tests. a standardized protocol, based on hunter et al.,23 was used during testing. statistical analysis variables were calculated as means and sds or frequencies and percentages, as appropriate. multivariable linear regression was used to evaluate the strength of association between walking ability (objective and subjective) and balance self-efficacy (dependent variable). regression diagnostics were performed to ensure assumptions for linear regressions were met. to generate the most parsimonious model, analysis was adjusted for age, level of amputation, number of comorbidities and number of medications. these variables were selected based on the literature and their clinical significance.2,28,29 due to the small sample size of the current study, no subgroup analysis based on level of amputation was performed. significance level was set to p<0.05. statistical analysis was performed using the ibm spss statistics version 24.0 (ibm corporation, armonk, ny). results demographics are summarized in table 1. twenty-seven participants were included in the study. many participants (77.8%, n=21) had transtibial amputations; the remainder of the participants had transfemoral amputations. almost 2/3rds of the study participants were male (63%, n=17). the mean balance self-efficacy rating using the abc scale was 69.48 ± 14.50, with scores ranging from 35.63 to 89.69. results from objective and subjective measures of walking ability are presented in table 2. after adjusting for confounders, single-task and dual-task walking velocity along the 6m straight path were both found to be independently associated with self-efficacy of balance (table 3). for every 1cm/s increase in walking velocity along a 6m path, balance self-efficacy increases by 0.32 for single-task (p=0.011) and 0.28 for dual-task conditions (p=0.039). https://doi.org/10.33137/cpoj.v5i1.36695 4 frengopoulos c, zia z, payne m.w.c, viana r, hunter s.w. association between balance self-efficacy and walking ability in those with new lower limb amputations. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.4. https://doi.org/10.33137/cpoj.v5i1.36695 issn: 2561-987x association between balance self-efficacy and walking ability frengopoulos et al., 2022 cpoj table 1: demographic and study characteristics of older adults with first major, unilateral lower limb amputation at discharge from prosthetic rehabilitation. (n=27). characteristics values age (years) 63.6 ± 9.3 sex (men) 17 (63.0%) body mass index (kg/m2) 27.4 ± 5.4 amputation level (n, % transtibial) 21 (77.8%) time between amputation and discharge (days) 142.6 ± 74.6 fall in the previous 12 months? (n, % yes) 19 (70.4%) self-reported number of falls 2.1 ± 2.7 montreal cognitive assessment 25.7 ± 2.9 primary etiology of amputation (n, %): diabetes mellitus 17 (63.0%) peripheral vascular disease 4 (14.8%) diabetes mellitus and peripheral vascular disease 1 (3.7%) trauma, cancer or other (clotting disorders, infection, etc.) 5 (18.5%) number of medications 10.2 ± 4.6 number of comorbidities 5.4 ± 2.2 walking aid use at discharge (n, %): single cane 3 (11.1%) two canes 3 (11.1%) forearm crutches 1 (3.7%) standard walker 1 (3.7%) rollator walker 19 (70.4%) table 2: results of objective and subjective measures of walking ability at discharge from prosthetic rehabilitation. (n=27). abbreviations: peq, prosthesis evaluation questionnaire. variables mean ± sd objective: 6m straight path, single task walking velocity (cm/s) 48.98 ± 25.26 6m straight path, dual task walking velocity (cm/s) 42.54 ± 22.86 l-test, single-task walking time (seconds) 79.89 ± 53.01 l-test, dual-task walking time (seconds) 97.90 ± 70.40 subjective: peq ambulation subscale 68.22 ± 19.09 peq 13a: walking ability w/prosthesis 81.82 ± 16.32 peq 13b: ability to walk in close spaces w/prosthesis 76.33 ± 24.80 peq 13c: walk up-stairs w/prosthesis 78.16 ± 20.30 peq 13d: walk down stairs w/prosthesis 77.72 ± 21.48 peq 14e: walk up hill w/prosthesis 54.76 ± 33.17 peq 14f: walk down-hill w/prosthesis 53.71 ± 32.14 peq 14g: walk sidewalks w/prosthesis 77.83 ± 30.88 peq 14h: walk on slippery surfaces w/prosthesis 45.43 ± 30.77 peq question 16b satisfaction with walking 88.44 ± 11.80 single-task performance on the l-test and satisfaction with walking were also independently associated with selfefficacy of balance (table 3). for every one second decrease in performance on the l-test balance self-efficacy increases by 0.17 (p=0.035), and for every 1-point increase in satisfaction with walking self-efficacy increases by 0.60 (p=0.019). no associations between the other objective or subjective measures and balance self-efficacy were found. discussion this study is the first to investigate associations between subjective and objective measures of walking ability and balance self-efficacy in those with lla at discharge from prosthetic rehabilitation. we identified that straight path walking velocity under single and dual-task conditions, time to complete the single-task l-test and self-reported satisfaction with walking were associated with balance selfefficacy at discharge from rehabilitation. this indicates that performance on both objective and subjective measures of walking ability influence the reported balance self-efficacy of individuals with lla at this point in the prosthetic rehabilitation process. the relationship between self-efficacy and motor learning is circular. as individuals gain self-efficacy they create more challenging goals; striving for these goals benefits motor learning and performance, leading to further goal setting.30 according to bandura, the more mastery experiences that one has, the higher they perceive their ability;15 this perception of one’s capabilities may be more related to performance than physical ability itself.14,15 this is an important consideration for individuals with lla, as levels of balance self-efficacy tend to be low.12,31 the results from the current study highlights the relationship between walking ability and self-efficacy of balance at a single point in the rehabilitation journey. further research is needed to fully understand the longitudinal relationship between selfefficacy, goal setting and walking ability for those with llas. table 3: results of multivariable linear regression for the association of objective (6m straight path and l-test walking tests) and subjective (peq) measures of walking ability on self efficacy (activities-specific balance confidence scale). abbreviations: β, regression coefficient; ci, confidence interval; peq, prosthesis evaluation questionnaire. *adjusted for age, level of amputation, number of comorbidities, number of medications. gait variable unadjusted β (95% ci) adjusted β (95% ci)* objective: 6m straight path: single task walking velocity (cm/s) dual task walking velocity (cm/s) 0.37 (0.19, 0.55), p<0.001 0.35 (0.13, 0.57), p=0.003 0.32 (0.08, 0.56), p=0.011 0.28 (0.02, 0.54), p=0.039 l-test: single-task walking time (seconds) dual-task walking time (seconds) -0.17 (-0.26, -0.09), p<0.001 -0.11 (-0.18, -0.04) p=0.005 -0.17 (-0.33, -0.01), p=0.035 -0.08 (-0.20, 0.04), p=0.164 subjective: peq ambulation subscale total score 0.35 (0.07, 0.63), p=0.016 0.22 (-0.08, 0.52), p=0.140 peq 16b: satisfaction with walking 0.80 (0.41, 1.18), p<0.001 0.60 (0.11, 1.08), p=0.019 https://doi.org/10.33137/cpoj.v5i1.36695 5 frengopoulos c, zia z, payne m.w.c, viana r, hunter s.w. association between balance self-efficacy and walking ability in those with new lower limb amputations. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.4. https://doi.org/10.33137/cpoj.v5i1.36695 issn: 2561-987x association between balance self-efficacy and walking ability frengopoulos et al., 2022 cpoj the 6m walk was the simplest measure performed by participants. in contrast, the l-test is more complex as it incorporates transfers and turning,22 and dual-task testing provides an additional cognitive challenge to mimic realworld multi-tasking.27 as individuals progress through prosthetic rehabilitation, they gain self-efficacy through mastery of simple tasks, external coaching from expert clinicians and vicarious experiences of observing fellow patients.13-15 confidence in performing more complex tasks develops later.15 the dual-task l-test is the most complex task that individuals were asked to perform in the current study. therefore, it is possible that participants have not yet developed balance self-efficacy relating to this task. it is expected that individuals will continue to develop selfefficacy of balance through mastery experiences of more difficult walking tasks as they begin to ambulate in the community.5 as self-efficacy is activity specific, a taskspecific intervention to improve self-efficacy may be a new target for interventions to improve walking ability for those with lla. task-oriented balance and walking interventions have been demonstrated to improve self-efficacy for individuals following a stroke.32 predictors of walking ability following lla have been widely described in the literature.2,33 previously identified factors tend to refer to physical or objective findings such as level of amputation, age, physical fitness and etiology of amputation,2,33 and have not included the influence of psychological factors. however, hamamura et al.34 did identify motivation to walk as a predictive factor for prosthetic rehabilitation in older adults with lla. previous research has also highlighted that while objective measures of walking ability improve following discharge from rehabilitation, subjective measures of walking ability do not.31 self-efficacy and motivation, along with other psychological factors, may help to explain why subjective measures of walking ability do not improve. the current study adds to the literature and highlights the relationship between the psychological factor of balance self-efficacy and walking ability for those with lla. more research on the relationship between psychological factors and their effects on subjective measures of walking ability is needed. study limitations these results represent individuals with unilateral lla at discharge from inpatient rehabilitation. more time with a prosthesis may impact self-efficacy of balance and the relationships described. the individuals in this study were >50 years of age, so results may not be relevant for younger cohorts or those with fewer comorbidities. transtibial and transfemoral levels of amputation were both represented in the current study, however no subgroup analysis based on level of amputation was performed due to small sample size. also, for those with transfemoral amputations, the type of knee componentry was not recorded. therefore, the current study is not able to comment on the impact of level of amputation or prosthetic components on the relationship between balance selfefficacy and walking ability. analysis based on level of amputation should be considered for further studies. also, the objective walking measures used in the current study only examine short walking distances. therefore, the association between objective measures of walking ability and balance self-efficacy cannot be generalized to longer walking measures or measures of endurance. finally, the current study has a small sample size, which may be underpowered to detect the changes in all variables measured. in future, larger sample sizes should be used to confirm the results. conclusion this study demonstrates the interplay between physical and psychological factors during rehabilitation for lla. straightpath walking velocity under single and dual-task conditions, performance on the l-test and self-reported satisfaction with walking are independently associated with self-efficacy of balance. however, the complex task of completing the dual-task l-test was not found to be associated. further research regarding other factors that may be associated with or influence self-efficacy is needed in the lla population. acknowledgements the authors would like to extend a thank you to all those who participated in this study. we sincerely appreciate your time and contribution to helping advance rehabilitation for this population. declaration of conflicting interests the authors have nothing to disclose. author contribution each author has made an equal contribution to the manuscript in the following areas: (1) concept or design of the work, or acquisition, analysis or interpretation of data; (2) drafted or critically revised the article; (3) approved the version to be published; (4) participated sufficiently to take public responsibility for appropriate portions of the content. sources of support this work was supported by the st. joseph’s healthcare foundation cognitive vitality and brain health seed funding opportunity in london, ontario, canada. the funding body had no involvement in the conduct of the study. ethical approval the study was approved by the university of western ontario ethics board, and by the lawson health research institute clinical https://doi.org/10.33137/cpoj.v5i1.36695 6 frengopoulos c, zia z, payne m.w.c, viana r, hunter s.w. association between balance self-efficacy and walking ability in those with new lower limb amputations. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.4. https://doi.org/10.33137/cpoj.v5i1.36695 issn: 2561-987x association between balance self-efficacy and walking ability frengopoulos et al., 2022 cpoj resources impact committee. all individuals provided written informed consent prior to participating in the study. references 1.horgan o, maclachlan m. psychosocial adjustment to lower-limb amputation: a review. disabil rehabil. 2009;26(14/15):837–50. doi: 10.1080/09638280410001708869 2.sansam k, neumann v, o’connor r, bhakta b. predicting walking ability following lower limb amputation: a systematic review of the literature. j rehabil med. 2009;41(8):593–603. doi: 10.2340/16501977-0393 3.schaffalitzky e, gallagher p, maclachlan m, ryall n. understanding the benefits of prosthetic prescription: exploring the experiences of practitioners and lower limb prosthetic users. disabil rehabil. 2011;33(15–16):1314–23. doi: 10.3109/09638288.2010. 529234 4.hart-hughes s, latlief ga, 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10.1016/j.apmr.2017.12.008 24.legro mw, reiber gd, smith dg, del aguila m, larsen j, boone d. prosthesis evaluation questionnaire for persons with lower limb amputations: assessing prosthesis-related quality of life. arch phys med rehabil. 1998;79(8):931–8. doi: 10.1016/s00039993(98)90090-9 25.powell le, myers am. the activities-specific balance confidence (abc) scale. j gerontol a biol sci med sci. 1995;50a(1):m28–34. doi: 10.1093/gerona/50a.1.m28 26.miller wc, deathe ab, speechley m. psychometric properties of the activities-specific balance confidence scale among individuals with a lower-limb amputation. arch phys med rehabil. 2003;84(5):656–61. doi: 10.1016/s0003-9993(03)04807-4 27.yogev g, hausdorff jm, giladi n. the role of executive function and attention in gait. mov disord. 2008;23(3):329–472. doi: 10.1002/mds.21720. 28.murdoch g. levels of amputation and limiting factors. ann r coll surg engl. 1967;40(4):204–16. https://doi.org/10.33137/cpoj.v5i1.36695 7 frengopoulos c, zia z, payne m.w.c, viana r, hunter s.w. association between balance self-efficacy and walking ability in those with new lower limb amputations. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.4. https://doi.org/10.33137/cpoj.v5i1.36695 issn: 2561-987x association between balance self-efficacy and walking ability frengopoulos et al., 2022 cpoj 29.frengopoulos c, burley j, viana r, payne mw, hunter sw. association between montreal cognitive assessment scores and measures of functional mobility in lower extremity amputees after inpatient rehabilitation. arch phys med rehabil. 2017;98(3). doi: 10.1016/j.apmr.2016.06.012 30.kyllo lb, landers dm. goal setting in sport and exercise: a research synthesis to resolve the controversy. j sport exerc psychol. 1995;17(2):117–37. doi: 10.1123/jsep.17.2.117 31.cieslak g, omana h, madou e, frengopoulos c, viana r, payne mw, et al. association between changes in subjective and objective measures of mobility in people with lower limb amputations after inpatient rehabilitation. am j phys med rehabil. 2020;99(11). doi: 10.1097/phm.0000000000001490 32.salbach nm, mayo ne, robichaud-ekstrand s, hanley ja, richards cl, wood-dauphinee s. the effect of a task-oriented walking intervention on improving balance self-efficacy poststroke: a randomized, controlled trial. j am geriatr soc. 2005;53(4):576– 82. doi: 10.1111/j.1532-5415.2005.53203.x 33.kahle jt, highsmith mj, schaepper h, johannesson a, orendurff ms, kaufman k. predicting walking ability following lower limb amputation: an updated systematic literature review. technol innov. 2016;18(2–3):125–37. doi: 10.21300/18.2-3.2016.125 34.hamamura s, chin t, kuroda r, akisue t, iguchi t, kohno h, et al. factors affecting prosthetic rehabilitation outcomes in amputees of age 60 years and over. int. j. med. res. 2009;37(6):1921–7. doi: 10.1177/147323000903700630 https://doi.org/10.33137/cpoj.v5i1.36695 howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 issn: 2561-987x volume 2, issue 2 2019 (online) professional opinion all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). https://doi.org/10.33137/cpoj.v2i2.33489 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation 1 open access canada’s prosthetic coverage volume 2, issue 2, article no.4, 2019 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index professional opinion canada’s prosthetic coverage: a review of provincial prosthetic policy howard c.w1*#, saraswat d.k2#, mcleod g3, yeung a3, jeong d4, lam j5 1 cumming school of medicine, university of calgary, calgary, alberta, canada. 2 faculty of medicine & dentistry, university of alberta, edmonton, alberta, canada. 3 max rady college of medicine, university of manitoba, winnipeg, manitoba, canada. 4 faculty of medicine, university of toronto, toronto, ontario, canada. 5 faculty of medicine, mcgill university, montreal, québec, canada. introduction following loss of a limb, proper prosthetic treatment allows patients to perform activities of daily living and improves general health and wellness.1 conversely, improper prosthetic care can lead to serious long-term complications and comorbidities including increased risk of falls, pain, and significant musculoskeletal and dermatological complications.2 patients who lack access to prosthetic care entirely may become sedentary, exacerbating many comorbidities that are common in this population such as diabetes mellitus and cardiovascular disease.3 the average age-adjusted incidence of lower limb amputation in canada was reported as 22.9 per 100,000 individuals, increasing over the years 2006-2011.4 according to estimates by the war amputations of canada, approximately 50,000 canadians are living with limb loss.5 amputation occurs due to a variety of causes, including complications of diabetes, vascular disease, infection, cancer, trauma, and congenital disorders.6 regardless of the cause, patients living with amputation experience a loss in their daily functioning and face lifelong physical and emotional challenges. proper prosthetic care leads to improved functional outcomes, reduced comorbid disease and hospitalizations, and lower healthcare costs.7 therefore, it is crucial to provide the optimal prosthesis for the patient. unfortunately, acquiring prosthetic limbs can be challenging for patients. a major barrier is the high costs of these devices, which includes not only the prosthetic components, but also the entire prosthetic treatment process, auxiliary parts for the limb, repairs of the limb, and eventual replacements.5 high costs may be driven by a low demand for prosthetic devices due to the relatively low incidence of amputations in the general population as well abstract the canadian healthcare system serves as an example of equity and federal service to citizens across the world. however, it is not without its challenges. prosthetic coverage across canada is highly variable and largely unable to provide equal coverage for canadian persons living with amputation. many persons with limb loss are forced to rely upon personal resources, fundraising, or the charity of nongovernmental organizations in order to meet this basic healthcare need. this disparity in the canadian healthcare system is unusual and largely undescribed in the literature. we thus explore the nature of canadian healthcare prosthetic coverage across canada, investigating the variability in coverage, presence of prosthetic coverage policies, clarity of policy, eligibility criteria, and interval of prosthetic replacement. our findings highlight potential areas for improvement within current canadian healthcare policy. citation howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 keywords prosthesis, amputees, amputation, limb loss, healthcare, rehabilitation, healthcare, prosthetic coverage *corresponding author calvin w. howard cumming school of medicine, university of calgary, calgary, alberta, canada. phone: +1 (587) 987-7723 e-mail: calvin.howard@ucalgary.ca orcid: https://orcid.org/0000-0001-5576-9608 # howard c.w and saraswat d.k contributed equally. doi: https://doi.org/10.33137/cpoj.v2i2.33489 article info received: december 23, 2019 accepted: february 12, 2020 published: march 16, 2020 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v2i2.33489 mailto:calvin.howard@ucalgary.ca https://doi.org/10.33137/cpoj.v2i2.33489 howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 2 cpoj howard et al. 2019 canada’s prosthetic coverage as the need to customize the prosthesis to each patient. furthermore, the total cost of prosthetic care can vary greatly depending on the level of amputation and functional needs. although objective canadian data is unavailable, research from the united states’ department of veteran affairs suggests that 5-year projected unilateral upper limb prosthetic costs range between $31,129 to $117,440, while 5-year projected lower-limb prosthetic costs range from $82,251 to $228,665 for veterans with limb loss.8 in canada, healthcare is largely a provincial responsibility, with the exception of eligible indigenous people, canadian forces personnel, veterans, inmates of federal prisons, and certain groups of refugees for whom the federal government is responsible for providing healthcare.9 to provide provincial healthcare, the provinces and territories created thirteen insurance plans, one for each province or territory. notably, the canada health act only requires provinces to cover hospital services, physician services, and surgical-dental services provided by hospitals, medical practitioners or dentists.10 while provinces may choose to cover further services, they are not required to do so, which has resulted in considerable variability between provincial service coverage. in general, funding for prosthetic devices can come from federal or provincial programs, (including workers insurance for work related injury), private health insurance plans, philanthropic organizations such as the war amputations of canada or a combination of these sources. often, a part of the cost is covered by a patient’s personal resources or through individual fundraising campaigns. examining governmental coverage of prosthetic devices across canada reveals considerable variation from province to province. we sought to assess these variations to determine the extent to which interprovincial access to prosthetic care in canada is equitable, according to policy. methodology policy review information was first gathered through communication with relevant stakeholders (listed in table 1), such as: government officials involved with pharmacare or the ministries of health; national and provincial representatives for persons with limb loss identified through conversation with the war amputations of canada; organizational leaders, such as the president of persons with limb loss associations; and prosthetists and physiatry specialists in amputation rehabilitation care, identified by communication with the aforementioned stakeholders. initial conversations with stakeholders allowed a holistic approach to appraising prosthetic policies guided by values of stakeholders across the country. at least two sources were used for each province. prosthetic device coverage information was then identified by review of provincial policy documents and provincial websites. we extracted the most up to date information relevant to coverage of prosthetic devices from the prosthetic provincial policy documents. each document’s sections relevant to prosthetics; replacement; eligibility; advanced devices; and coverage were read. specific phrases were searched using keywords: “3r106”, “12k42”, “knee”, “elbow”, “humeral”, “femoral”, “myo-“, “myoelectric”, “advanced”, “micro”, “microprocessor”, “eligible”, “eligibility”, “criteria”, “replacement”, and “year”. information was then condensed and paraphrased to fit within table 2. we compared four factors between provinces: patients’ eligibility for prosthetic coverage, the coverage available for basic prosthetic components, the coverage available for advanced prosthetic components, and replacement intervals. in our search, we defined a “basic prosthetic component” as a device not enhanced by myoelectric capability, micro-processing chips, or other features relying on onboard programming to modulate activity. advanced prosthetic components were defined as any devices with myoelectric capability, micro-processing chips, or other electrical features. for the purposes of this paper, only provincial health coverage was assessed, specifically including british columbia, alberta, saskatchewan, manitoba, ontario, quebec, new brunswick, nova scotia, prince edward island, and newfoundland and labrador. health coverage in the territories, federal funding programs, and workers’ compensation insurance programs were not examined. primary focus was placed on coverage within the province’s primary healthcare policy. patient eligibility criteria for prosthetic coverage prosthetic policy documents for each province were reviewed for inclusion or exclusion criteria regarding patients qualifying for prosthetic device coverage. further criteria for eligibility of prosthetic device funding were identified and compared. basic prosthetic device funding comparison we chose the ottobock ergoarm 12k42 (mechanical body-powered elbow joint), valued at $4552, and knee 3r106 (pneumatic polycentric knee), valued at $1923, as representations of basic function prosthetic components due to their ubiquitous nature across healthcare funding schedules and being considered base-function by the prosthetic community. wholesale costs as of july 10th, 2019 were obtained from a canadian prosthetic retailer. however, these values do not account for additional lab fees charged for time, product, and skills, or for the prosthesis socket fitting (i.e. the value of the entire prosthetic device treatment). it is likely that the use of component prices as a surrogate for overall prosthetic coverage may result in an overestimation of funding coverage for prosthetic services. however, these methods yield insight into general funding policy trends across different policies. funding catalogues and coverage plans for each province were investigated and used to compare the proportion of basic-level prosthetic component covered. percentage of basic-level component covered was expressed as the wholesale cost of the prosthetic component divided by the maximum funding value or the maximum percentage covered as per prosthetic coverage policy. https://doi.org/10.33137/cpoj.v2i2.33489 howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 3 cpoj howard et al. 2019 canada’s prosthetic coverage advanced prosthetic device funding comparison prosthetic policy documents for each province were reviewed for any description of funding of advanced prosthetic devices. due to variance in advanced prosthetic coverage policies, general policy for “advanced prosthetic devices” as described in policy documents were recorded. if further specification of advanced prosthetic device was made, the highest amount funded was documented. no standard advanced prosthetic component could be used to compare funding due to variance in prosthetic coverage policies across canada. replacement interval all prosthetic policy documents for each province were reviewed for frequency at which prosthetic devices could be replaced under their respective prosthetic programs. as all provinces allowed replacement upon medical need and review, only the typical interval of replacement was recorded. any variation of typical replacement interval program was also reported. province provincial policy document provincial official clinician contact (physiatrist and/or prosthetist) person with limb loss stakeholder british columbia pharmacare, prosthetic and orthotic program pharmacare n/a waramps canada alberta alberta aids to daily living, general policy & procedures manual alberta aids to daily living, orthotic and prosthetic benefits n/a glenrose amputation rehabilitation program community prosthetic facility alberta amputee and sports association waramps canada saskatchewan saskatchewan aids to independent living program, general policies extended benefits, drug plan and extended benefits branch, ministry of health n/a waramps canada manitoba smd foundation, the assistive technology funding guide manitoba health, seniors and active living n/a waramps canada ontario limb prostheses policy and administration manual n/a ottawa rehabilitation centre waramps canada quebec schedule 1, tariff for devices which compensate for a motor deficiency and insured related services n/a amputee program institut de réadaptation gingras-lindsay de montréal waramps canada newfoundland & labrador n/a n/a regional adult rehabilitation, palliative care, and geriatrics program waramps canada new brunswick social development prosthetic program policy n/a institute of biomedical engineering/atlantic clinic for upper limb prosthetics waramps canada nova scotia arm & leg prostheses program, prosthetists guide n/a n/a waramps canada prince edward island health pei, pei pharmacare formulary n/a n/a waramps canada table 2: traits of prosthetic coverage across the provinces. policy documents were reviewed and details are reported to the extent which they are reported in policy documents. coverage is defined as a percentage covered according to policy and procedure list of a basic upper prosthetic component (ergoarm 12k42, 4552$), and a basic lower prosthetic component (ottobock 3r106, 1923$). province coverage basic prosthetic replacement interval coverage advanced prosthetic reference(s) british columbia upper limb: 75% lower limb: 100% 3 years: general myoelectric coverage: no information microprocessor knee: no coverage 11,12 alberta upper limb: 93% lower limb: 100% 2 years: basic functionality devices 3 years: myoelectric arm 5 years: microprocessor knee myoelectric coverage: requires pre-approval microprocessor knees: grant up to $6000 13,14 saskatchewan upper limb: 100% lower limb: 100% 3 years: general myoelectric coverage: case-by-case microprocessor knees: up to $15 000 15 manitoba upper limb: 100% lower limb: 100% 2 years: general myoelectric coverage: no information microprocessor knees: no information 16 ontario upper limb: 75% lower limb: 75% 3 years: basic functionality devices 3 years: externally powered devices myoelectric coverage: up to 75% or maximum limit microprocessor knees: no information 17,18 quebec upper limb: 100% lower limb: 100% present, not further described myoelectric coverage: up to $8000, variable by product microprocessor knees: no information 19 newfoundland & labrador upper limb: n/a lower limb: n/a n/a n/a 20,21 new brunswick upper limb: 100% lower limb: 100% 5 years: general myoelectric coverage: ineligible microprocessor knees: maximum $20 000 22 nova scotia upper limb: 100% lower limb: 100% 4 years: adults 2 years: children myoelectric coverage: $5089 maximum microprocessor knees: maximum $6511 23 prince edward island upper limb: n/a lower limb: n/a n/a n/a 24 table 1: sources of prosthetic device coverage information by province and source type. https://doi.org/10.33137/cpoj.v2i2.33489 howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 4 cpoj howard et al. 2019 canada’s prosthetic coverage results eligibility for coverage of prosthetic devices we found eight provinces to have formal government policies regarding prosthetic device coverage (table 1). in all the provinces offering governmental coverage of limb prosthetic devices, coverage eligibility requires that the device is medically necessary and prescribed as such by a certified medical practitioner (e.g. physician, nurse practitioner), and the device be fabricated and provided by a licenced prosthetist.12,14–16,18,19,22,23 however, in some provinces additional variable stipulations on whom is eligible to receive coverage beyond the prior mentioned baseline criteria. british columbia, saskatchewan, manitoba, ontario, and prince edward island all require no additional governmental funding.12,15–18,24,25 prince edward island also requires no membership with the royal canadian mounted police nor canadian armed forces.25 notably, in new brunswick, patients must have demonstrated financial need and be registered with social development health services in order to be considered eligible for any prosthetic funding from the provincial government.22 policies and procedures vary across the provinces, as do their clarity. for example, british columbia requires preapproval of a device to consider funding its cost, and requires pre-approval for device repairs over $400,12 although retroactive approval may be possible. other provinces such as alberta and québec require patients access governmental programs outside of healthcare to receive funding.14,19 within alberta aids to daily living, the governmental program which manages prosthetic devices, the bureaucratic process of funding a prosthetic device is outlined.13 however, this is not the case amongst the majority of provinces, and stakeholders anecdotally reported confusion in navigating governmental systems during our interviews. according to our investigations, two provinces may not administer any government funding for prosthetic limbs. prince edward island (pei) does not employ a formal governmental coverage policy at the time of this writing;24 however, according to personal correspondence with a representative from health pei, basic model prosthetic devices may be covered in full by the pei government, implying a case-based approval system. additionally, newfoundland and labrador do not have an available prosthetic device policy,20,21 although correspondence with eastern health newfoundland & labrador has revealed that they provide case-by-case funding for those in financial need. coverage of basic prosthetic devices varies widely by province “basic device” is a term which must be defined separately from basic function, as most provincial policies denote a mandate to provide devices which will achieve “basic functionality.” despite this similar mandate, there is wide variation in the devices which are deemed necessary to achieve basic function. some policies implicitly assert, via absence of funds for advanced components, that basic devices should always be sufficient to enable basic functioning. other policies acknowledge, via funding availability, that advanced components may be needed to achieve basic functioning. this discrepancy may be partly due to different definitions of “basic function”, with some referencing activities of daily living, others instrumental activities of daily living, and others referencing ability to function and work more broadly. for example, manitoba’s policy identifies a mandate to provide prosthetic devices to “assist in the basic activities of daily living”.16 activities of daily living (adls) standardly refers to grooming, dressing, toileting, transferring/ambulating, and eating.26 british columbia’s policy also contains a mandate to help patients “achieve or maintain basic functionality”,11 although this is defined on a case-by-case basis.12 alberta uses a classification system similar to the u.s medicare functional classification level to determine whether a patient will benefit from a prosthesis and therefore whether they are eligible for funding for certain prosthetic components.27 saskatchewan refers to activities of daily living in a broader sense including higher-functioning activities like physically-demanding gainful employment in manual labour.15 in addition to variation in definition of basic function, for provinces offering coverage of prosthetic limbs, the benefit limits by device vary widely, as demonstrated by our comparison of the degree of coverage for the ottobock ergoarm 12k42 elbow joint and ottobock knee 3r106 knee joint (table 2). direct province-to-province comparison was hampered by non-standard terminology and generally disparate policy approaches. half of provinces achieved 100% coverage of both basic components: saskatchewan, quebec, nova scotia, new brunswick, and manitoba. alberta achieved 93% coverage of the elbow and 100% of the knee. british columbia achieved 75% elbow coverage and 100% knee coverage. ontario achieved 75% coverage for both, up to a maximum benefit amount. some provinces have alternative programs providing additional coverage for specific groups, such as those on social assistance due to disability or other causes (table 2). notably, prince edward island and newfoundland have no enshrined prosthetic policy, simply stating funding is determined on a case-bycase basis with no data regarding degree of coverage. coverage of advanced prosthetic devices varies widely by province given the significant variability in advanced prosthetic coverage (table 2), we highlight the differences. ontario and saskatchewan provide the most coverage for advanced prosthetic devices when deemed necessary for a given patient. ontario offers $15,000 towards myoelectric upper limb devices, up to a maximum of $17,690 for select advanced components.17,28 saskatchewan covers microprocessor knees up to $15,000, and considers myoelectric coverage amounts on a case-by-case basis.15 alberta and québec offer some additional funding for advanced components relative to basic components, but the benefit limits are in the $5,000 $8,000 range, similar to those of basic devices.14,19 alberta only contributes up to $6000 towards the cost of microprocessor knees, for example, and less for other advanced prostheses.14 alberta policy also indicates that myoelectric upper extremity devices will be funded with prior approval after at least one year of body-powered prosthesis use, but without reference to other specific https://doi.org/10.33137/cpoj.v2i2.33489 howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 5 cpoj howard et al. 2019 canada’s prosthetic coverage criteria.13 new brunswick lies in the middle of these examples: the province offers up to $20,000 or $10,000 for aboveand below-knee prostheses respectively and up to $10,000 for arm prostheses; however, myoelectric prostheses are explicitly excluded from this coverage.22 unlike the aforementioned provinces, manitoba and british columbia provide no additional funding for advanced components. british columbia and manitoba may allow residents to select an advanced device in lieu of a basic device, with the benefit limit for the corresponding basic device applying.12,22 in both of these provinces the benefit limit for any device does not exceed $5,000,12,16 which may cover only a small proportion of the cost of an advanced device. maintenance and repair of prosthetic device varies by province provinces differ in the replacement interval for prosthetic limbs, ranging from 2 years in manitoba to 5 years in new brunswick.16,19,22 fortunately, claims for repairs and adjustments are considered throughout the device lifespan when necessary due to damage, a change in the patient’s medical condition, or growth.12,14–16,18,19,22,23 discussion coverage eligibility and availability while most provinces allow all residents to access basic prosthetic care, significant shortcomings exist. our review of existing policy documents details that only 30% of provinces have policy documents detailing eligibility criteria beyond basic requirements. there is no indication that the criteria are appropriately inclusive or restrictive, or if they were developed with the input of stakeholders. notably, 20% of provinces require applicants to demonstrate financial need to access provincial funding for prostheses, while an additional 20% of provinces require demonstration of financial need to waive copayments or co-insurances. the criteria to demonstrate financial need can be restrictive and vary by province; for example, within new brunswick a life insurance policy may count as an asset and thereby disqualify patients from financial assistance in purchasing a prosthetic device. furthermore, 50% of provinces exclude a patient from receiving healthcare funding if they are eligible for funding from other governmental programs. these exclusions may lead to inequitable access to prosthetic devices and may prevent patients from achieving 100% coverage of a prosthetic device by combining coverage policies. additionally, newfoundland and labrador and pei have no publicly available documented coverage policy, and pei coverage is organized within the queen elizabeth hospital itself. individuals in these provinces who are unable to afford prosthetic devices via personal means or private insurance may thus be denied the opportunity to receive them, resulting in inequitable access to prosthetic care. variable and insufficient prosthetic coverage from our review of the provincial funding for prosthetic devices, we saw a wide range in the maximum funding available to cover various prosthetic components. only 50% of the provinces surveyed had 100% coverage of both the upper and lower limb basic prosthetic components (table 2). the degree of funding was variable across provinces, and it is notable that alberta and ontario require patients to cover at least 25% of their device, although in the case of alberta, there is a maximum costshare portion. in both of these provinces, patients with demonstrable financial need (such as receiving social assistance) can receive 100% coverage of basic prostheses. in provinces without coverage policies, it is impossible to know what proportion of value patients will pay as cases are considered on an individual basis. comparing access to funding is difficult due to the variability in existing procedural policies for applying to receive funding for prosthetic devices, with some provinces having a defined procedure in place13 but other provinces such as manitoba lacking procedural definition entirely.13,16 given the high upfront cost of prosthetic devices and variable coverage policies, patients suffer either uncertainty or a significant cost burden, especially those who do not have alternative funding sources or personal savings. for those provinces with a prosthetic coverage policy, there is a general aim to provide funding for “basic” functionality prosthetic devices; however, there is a lack of consistency between provinces on what constitutes basic functionality and which types of prosthetic devices may be necessary to achieve it. not only are definitions variable, which results in variable prosthetic coverage, but the definitions can result in exclusive coverage; for example, while many provinces require no other governmental funding, prince edward island will not cover members of the royal canadian mounted police nor canadian armed forces (table 2).25 saskatchewan and alberta currently lead as examples of clear definitions to guide funding devices that will return patients to their optimal functional level, not just provide minimal functionality, although correlating this classification method with the device funding actually received was beyond the scope of this review. an additional source of provincial variation in coverage amounts may be the outdated nature of benefit schedules. for example, ontario and bc benefit amounts appear to have been last updated in 2012.12,18 if benefit amounts are outdated, they may be insufficient to cover the full amount of current prosthetic devices on the market. if more current models of prosthetic devices are not listed in the funding schedule, they may not be covered. this is especially pertinent in the age of advancing prosthetic technology, in which new prosthetic devices may not be covered solely due to policy update neglect. provision of advanced prosthetic devices has been demonstrated to be cost-effective.29-32 despite evidence of cost-effectiveness and higher levels of safety,30 provincial approaches to coverage of advanced prosthetic devices are variable. coverage for devices with advanced functionality is generally more restrictive and fluctuant across canada, with 40% of provinces having no coverage policy (table 2). for provinces that do have a coverage policy, benefit amounts range from $5000 to $20,000. given that a microprocessor knee may cost upwards of $40,000 to $45,000, even a maximum co-insurance funding amount leaves patients paying a significant portion https://doi.org/10.33137/cpoj.v2i2.33489 howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 6 cpoj howard et al. 2019 canada’s prosthetic coverage personally, which may be impossible for middle-income earners who may not qualify for financial assistance but lack the resources to bear these costs on their own, further increasing the burden on patients.17 furthermore, the success of funding requests and resultant provision of devices remains unknown, complicated by the case-based review system in some provinces with unstated criteria. advanced prosthetic coverage remains limited, with the majority of provinces lacking coverage, provinces being highly particular in what prosthetic devices are covered, and coverage plans falling far short of total coverage. variable prosthetic replacement interval our work demonstrates that 50% of provinces have replacements offered every three years (table 2). no difficulties with replacement interval were noted during our literature review, interviews with persons with limb loss, nor discussion with clinicians. however, difficulties may still arise. prosthetics are at variable risk of degradation dependent upon prosthetic quality, activity level, and anatomic location. for example, a farmer utilizing a belowthe-knee prosthesis daily may have significant wear and component failure within three years, prior to allowed replacement. this may lead high-activity and high functioning patients to suffer significant repetitive financial drain associated with repeat co-payment for necessary prosthetic maintenance. coverage of prosthetic devices: canada’s equality prosthetic access and coverage should be based on need, irrespective of a patient’s identified province of residency. the described interprovincial inequality is unfortunately consistent with other growing healthcare inequalities across canada.33 the widening gap in healthcare between provinces may be attributed to differential fiscal capacities of provinces, along with differing provincial government priorities.34 differences in populations that comprise each province may also play a role, where there is a growing young population in alberta while the aging population is on the rise in maritime provinces, and variable prevalence of diabetes may result in proportionately variable prosthetic demands.34 the specific example of prosthetic coverage reveals the lack of a national standard as a contributing factor to the observed disparities between provinces. altogether, this issue highlights the important need to establish a standard to allow for equal access to appropriate funding of prostheses across canada. a recent report released by the college of family physicians of canada has outlined the responsibilities of the federal government as “providing adequate funding, establishing national standards, enforcing legislation, and ensuring all regions of canada receive equal and appropriate resources”.35 similarly, the world health organization (who) has recently advocated for the prioritization of universal health coverage for prosthetic and orthotic devices and services.36 our work demonstrates that these goals are not being met in canada. importantly, the who has published an implementation manual for the standardization of prosthetic and orthotics services.36 this document provides a thorough summary of different domains which should be addressed and can serve as a valuable resource in the development of federal standards as advocated by the college of family physicians of canada.35 another area the who emphasizes is the accessibility of cost-effective prosthetic devices, even those which are deemed “sophisticated” or expensive. in canada, there is notable resistance to the implementation of advanced prosthetic devices, as seen in the number of provinces which do not routinely fund devices such as myoelectric prostheses and microprocessor knees. despite the higher costs of these devices, these types of prosthesis provide meaningful benefit to a patient’s quality of life and overall health. for example, the canadian agency for drugs and technologies in health, a federal organization which reviews the evidence behind medical interventions, concluded in 2009 that there is cost benefit in the use of microprocessor knees,37 congruent with other work.29–32 in 2016 the national health service of england instituted a policy which provided coverage for microprocessor knees based on evidence of its cost-effectiveness.38 currently, no provinces in canada have a policy to fully fund these documented cost-effective devices. limitations and future directions some inherent limitations are posed by the nature of this work. the lack of standardized policies across provincial coverage documents results in difficulty achieving comparability. while some provinces have extensively detailed lists of prosthetic devices which are funded and to what degree, other provinces may only list a handful, if any at all. analysis of degree of coverage also relies upon knowing the cost of a given prosthetic component. however, the cost of a given prosthetic device is not readily available to the canadian public, as most openly available information details government funding rather than specific market values. similarly, the value of prosthetic devices we achieved in discussion with a canadian prosthetics retailer represents wholesale cost, which means markup associated with skills and services cannot be accounted for, yet they are crucial components of adequate care and provision of devices. in addition, we analyzed only single components of the prosthetic device, not the entire prosthesis system that is required to treat a patient. this means we likely overestimate the degree to which provinces cover prosthetic devices, and therefore underestimate the degree to which funding of clinical services is necessary to ensure optimal outcomes. it should be emphasized that the presented results are based on published policy, and do not take into account actual success rates of funding applications. in discussion with stakeholders, difficulty accessing full governmental funding was commonly stated as a barrier to selecting the right component for the individual patient. future survey of canadian prosthetic users, prosthetists, physiatrists, and government officials would be a useful endeavour to identify potential areas of policy development. for example, assessing the degree to which eligibility criteria or lack thereof have been problematic for prosthetic users across the provinces would validate the need for such policies. given the lack of information regarding how prosthetic users fund their devices and to what degree they obtain less than ideal solutions due to funding limitations would yield crucial information in understanding the state of prosthetic coverage. collection of such data https://doi.org/10.33137/cpoj.v2i2.33489 howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 7 cpoj howard et al. 2019 canada’s prosthetic coverage would require a multi-institutional effort and would be a critical future direction. conclusion funding for prosthetic devices at the provincial level should be updated and equalized across provinces to reflect the realities in the cost of prosthetic care and services. failure to do so causes an unfair burden on the individual living with an amputation, often with dependence on geographic location. emphasis should also be placed on providing the right prosthesis for the right patient, with the goal of restoring optimal function and reducing complications and comorbidities. within an era of advancement of prosthetic technology, policy must adapt to ensure patients receive the best possible care.39 without such changes, it is the persons with limb loss and their health that suffer the consequence of a system that has failed them. our work has demonstrated the inability of the canadian healthcare system to provide both equitable and uniform prosthetic device coverage within all provinces, corroborating previous speculation.39 as such, the canadian healthcare system has difficulty meeting the standards set both by itself and the who.36,40 canada currently lacks uniform accessibility to prosthetic device coverage, uniform and equitable coverage of both basic function as well as advanced prosthetic devices, and uniform replacement intervals. adequate coverage has not only been demonstrated to increase quality of life, but also to be cost-effective in the long-term.30,31,41 we have identified core deficiencies in prosthetic device care that should be addressed for the betterment of canada and canadian patients. acknowledgements we would like to thank dr. jacqueline hebert for her integral role in guiding us through the process of creating this manuscript. declaration of conflicting interests the authors have no personal nor financial relationships to disclosure, nor any further conflicts of interest. author contribution • calvin w. howard, conceived the idea for the project, led data collection, and led manuscript writing. • dave k. saraswat, conceived the idea for the project, led data collection, and led manuscript writing. • graham mcleod, assisted in manuscript preparation and data collection. • albert yeung, assisted in manuscript preparation and data collection. • danielle jeong, assisted in manuscript preparation and data collection. • jack lam, assisted in manuscript preparation and data collection. sources of support this manuscript received no external supports. references 1.samuelsson ka, töytäri o, l sa, brandt a. effects of lower limb prosthesis on activity, participation, and quality of life: a systematic review. prosthet orthot int. 2012;36(2):145–58. https://doi.org/10.1177/0309364611432794 2.pascale ba, potter bk. residual limb complications and management strategies. curr phys med rehabil reports. 2014;2(4):241–9. https://doi.org/10.1007/s40141-014-0063-0 3.kurdibaylo sf. obesity and metabolic disorders in adults with lower limb amputation. j rehabil res dev. 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https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/1f0a6bbf-1815-4e55-8365-cff783c0caf1/download/health-aadl-manual-op-orthotics-prosthetics.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/1f0a6bbf-1815-4e55-8365-cff783c0caf1/download/health-aadl-manual-op-orthotics-prosthetics.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/ac69cc5f-ed58-4a41-ae91-1629b080e05c/download/aadl-manual-p-products-2019-04.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/ac69cc5f-ed58-4a41-ae91-1629b080e05c/download/aadl-manual-p-products-2019-04.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/ac69cc5f-ed58-4a41-ae91-1629b080e05c/download/aadl-manual-p-products-2019-04.pdf howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 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2018;15(1):49– 59. https://doi.org/10.1186/s12984-018-0405-8 32.liu h, chen c, hanson m, chaturvedi r, mattke s, hillestad r. economic value of advanced transfemoral prosthetics [internet]. rand corporation; 2017 [cited 2019 dec 23]. available from: https://www.rand.org/content/dam/rand/pubs/research_reports/r r2000/rr2096/rand_rr2096.pdf 33.key health inequalities in canada: a national portrait [internet]. pan-canadian health inequalities reporting initiative; 2018 [cited 2019 dec 23]. available from: https://www.canada.ca/content/dam/phacaspc/documents/services/publications/science-research/keyhealth-inequalities-canada-national-portrait-executivesummary/hir-full-report-eng.pdf 34.fiscal sustainability report 2018 [internet]. ottawa, office of the parliamentary budget officer; 2018 [cited 2019 dec 23]. available from: https://www.pbodpb.gc.ca/web/default/files/documents/reports/2018/fsr sept 2018/fsr_2018_25sep2018_en_2.pdf 35.the role of the federal government in health care: report 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https://www.england.nhs.uk/wp-content/uploads/2016/12/clincomm-pol-16061p.pdf 39.nielsen cc. issues affecting the future demand for orthotists and prosthetists: a study prepared for the national commission on orthotic and prosthetic education. national commission on orthotic and prosthetic education; 1996. 40. statues of canada. bill c-81 [internet]. canada; 2019 [cited 2019 dec 23]. available from: https://www.parl.ca/content/bills/421/government/c-81/c81_4/c-81_4.pdf https://doi.org/10.33137/cpoj.v2i2.33489 https://pubsaskdev.blob.core.windows.net/pubsask-prod/106724/106724-sail_general_policies_jan_2018.pdf https://pubsaskdev.blob.core.windows.net/pubsask-prod/106724/106724-sail_general_policies_jan_2018.pdf http://www.health.gov.on.ca/en/pro/programs/adp/information_technology/docs/limb_prostheses_externally_powered_manual.pdf http://www.health.gov.on.ca/en/pro/programs/adp/information_technology/docs/limb_prostheses_externally_powered_manual.pdf 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https://www.england.nhs.uk/wp-content/uploads/2016/12/clin-comm-pol-16061p.pdf https://www.england.nhs.uk/wp-content/uploads/2016/12/clin-comm-pol-16061p.pdf https://www.parl.ca/content/bills/421/government/c-81/c-81_4/c-81_4.pdf https://www.parl.ca/content/bills/421/government/c-81/c-81_4/c-81_4.pdf howard c.w, saraswat d.k, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 9 cpoj howard et al. 2019 canada’s prosthetic coverage 41.brodtkorb th, henriksson m, johannesen-munk k, thidell f. cost-effectiveness of c-leg compared with nonmicroprocessor-controlled knees: a modeling approach. arch phys med rehabil. 2008;89(1):24–30. https://doi.org/10.1016/j.apmr.2007.07.049 https://doi.org/10.33137/cpoj.v2i2.33489 https://doi.org/10.1016/j.apmr.2007.07.049 pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 issn: 2561-987x volume 2, issue 1 2019 (online) r e s e a r c h a r t i c l e all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x https://doi.org/10.33137/cpoj.v2i1.31008 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 1 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index research article an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques pousett b1, lizcano a2, raschke s.u3 1 barber prosthetics clinic, vancouver, british colombia, canada. 2 biomedical engineering department, universidad iberoamericana, ciudad de mexico, mexico. 3 make + applied research, centre for applied research & innovation (cari), burnaby, british columbia, canada. abstract background: rapid prototyping is becoming an accessible manufacturing method but before clinical adoption can occur, the safety of treatments needs to be established. previous studies have evaluated the static strength of traditional sockets using ultimate strength testing protocols outlined by the international organization for standardization (iso). objective: to carry out a pilot test in which 3d printed sockets will be compared to traditionally fabricated sockets, by applying a static ultimate strength test. methodology: 36 sockets were made from a mold of a transtibial socket shape,18 for cushion liners with a distal socket attachment block and 18 for locking liners with a distal 4-hole pattern. of the 18 sockets, 6 were thermoplastic, 6 laminated composites & 6 3d printed polylactic acid. sockets were aligned in standard bench alignment and placed in a testing jig that applied forces simulating individuals of different weight putting force through the socket both early and late in the stance phase. ultimate strength tests were conducted in these conditions. if a setup passed the ultimate strength test, load was applied until failure. findings: all sockets made for cushion liners passed the strength tests, however failure levels and methods varied. for early stance, thermoplastic sockets yielded, laminated sockets cracked posteriorly, and 3d printed socket broke circumferentially. for late stance, 2/3 of the sockets failed at the pylon. sockets made for locking liners passed the ultimate strength tests early in stance phase, however, none of the sockets passed for forces late in stance phase, all broke around the lock mechanism. conclusion: thermoplastic, laminated and 3d printed sockets made for cushion liners passed the ultimate strength test protocol outlined by the iso for forces applied statically in gait. this provides initial evidence that 3d printed sockets are statically safe to use on patients and quantifies the static strength of laminated and thermoplastic sockets. however, all set-ups of sockets made for locking liners failed at terminal stance. while further work is needed, this suggests that the distal reinforcement for thermoplastic, laminated and 3d printed sockets with distal cylindrical locks may need to be reconsidered. citation pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. doi: https://doi.org/10.33137/cpoj.v 2i1.31008 keywords prostheses, rapid prototyping, prosthesis design,3d printing, three dimensional printing, transtibial, socket strength, transtibial socket, thermoplastic, lamination, rapid additive manufacturing, lower-limb prostheses, *corresponding author brittany pousett, bsc, msc, certified prosthetist, head of research at barber prosthetics clinic, 540 se marine dr, vancouver, british colombia v5x 2t4, canada. email: brittany@barberprosthetics.com doi: https://doi.org/10.33137/cpoj.v2i1.31008 article info received: october 25, 2018 accepted: april 4, 2019 published: april 18, 2019 https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v2i1.31008 https://doi.org/10.33137/cpoj.v2i1.31008 mailto:brittany@barberprosthetics.com https://doi.org/10.33137/cpoj.v2i1.31008 pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 1 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index introduction a prosthetic socket is the interface connecting a person’s limb to the prosthetic components they use to interact with the environment. typically, sockets are manufactured from a plaster mold of a person’s limb which is modified to create an optimized shape.1 the socket is fabricated over the mold using materials including thermoplastics and laminated composites. 3d scanning systems are an alternate method to digitize the patient’s limb and modify the shape.1 often, the optimized shape is milled by a computer numerically controlled (cnc) milling machine and the socket is fabricated using traditional methods.1 as technology advances, the question emerges: ‘is this hybrid combination of digital scanning and design technology with traditional manufacturing methods the best approach?’. rapid prototyping (rp) offers a time efficient way of turning the digital design into a physical socket. rp involves sectioning the digital 3d socket design into thin slices, and sending it to a 3d printer that builds the shape layer by layer.1 over the past three decades, several groups have begun to create prosthetic sockets using rapid prototyping techniques.2,3,4 the prosthetist is responsible for choosing fabrication techniques that provide adequate strength and safety to their patients while maximizing function.5 currently, their decisions are not grounded on an evidence-based foundation as minimal evidence is available. furthermore, the evaluation of prosthetic sockets is not subject to any specific standard. iso 10328: prosthetics–structural testing of lower-limb prostheses is the test standard that is most commonly used to test prosthetic sockets.5 iso 10328 includes both static and cyclic strength tests applied in two different loading conditions, condition i: instant of maximum loading occurring early in the stance phase of walking, and condition ii: instant of maximum loading occurring late in the stance phase of walking, for three different weight limits, p3 body mass below 60 kg, p4 body mass below 80 kg, and p5 body mass above 100 kg.6 previously, this standard has been used in to evaluate the strengths of different socket attachment methods as this is frequently the point of failure in transtibial prostheses.5 current, kogleg & barth7 applied the static portion of the standard and tested 10 transtibial sockets for p5 at condition ii. they compared five reinforcement materials and two resins using a 4-hole distal attachment system and found that all 10 sockets failed the iso 10328 standard, breaking at the attachment plate.7 graebner & current5 investigated the strength of different socket attachment methods for composite sockets by applying the same portion of the standard as above. they found most attachment methods tested passed that aspect of the standard, especially when carbon reinforcement was used.5 finally, mackinnon8 used the same jig to perform the same test on three different socket attachment methods for thermoplastic sockets. he found two of the methods passed that portion of the standard when reinforced with fiberglass cast.8 gerschutz et al.9 took a different approach and applied the static part of the iso standard 10328 to evaluate sockets made in a variety of facilities. for forces applied at condition ii for p6 (a mass being further above 100 kg), they found most check sockets and definitive laminated sockets and all copolymer sockets failed the standard.9 these studies show that there is a lot of variability in sockets fabrication techniques and attachment methods that result in sockets passing or failing this portion of the standard. the goal of this project was to evaluate how 3d printed sockets compare to traditionally fabricated sockets made out of thermoplastics and laminated composites. this was done by applying the static portion of the iso 10328 standard for a variety of weight limits and load both early and late in the stance phase following the same testing protocol as these previous authors to allow for comparison.5, 7, 8 methodology socket fabrication & alignment this study chose to evaluate the strength of two different types of total surface bearing sockets, those made for cushion liners attached to a 5r1 block (“cushion sockets”) and those made for a locking liner attached distally via a 4-hole pattern lock (“locking sockets”) (figure 1). it tested three different fabrication materials, thermoplastic, laminated composited and 3d printed polylactic acid https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 2 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index (pla). a total of 36 sockets were tested. see figure 2 for more information. figure 1: the two types of total surface bearing sockets used; the left one was made for use with locking liners with a 4-hole pattern lock distally and the right one was designed for use with cushion liners and was attached to a distal attachment block and reinforced with fiberglass wrap. the structural test model was manufactured from a cast of an 80 kg male with a unilateral transtibial amputation that had been modified by an experienced prosthetist using common methods. this model was chosen as it was generic total surface bearing shape that was slightly conical, allowing multiple sockets to be removed without damaging the mold. it was slightly smaller than the average transtibial socket fit at the clinic, but it fit within the build height of the printer and it was feasible to print sockets within a reasonable timeframe of 8-9 hours. the socket is 15 cm from the patella tendon to the distal end and 32 cm in circumference around the patella tendon. one physical mold was fabricated identical to the modified cast while the other physical mold had the fillauer cylindrical lock dummy (chattanooga, united states) shape incorporated into the bottom of the shape. each mold was digitized using a spectra scanner (vorum, vancouver, canada) and converted to a 3d print file by additive o&p (charlotte, united states). 18 identically shaped sockets were fabricated from each of the models; 6 out of each different type of material using an identical process for each material type. all sockets were fabricated at barber prosthetics clinic by a registered prosthetic technician. see table 1 for detailed fabrication information. figure 2: an outline of all the sockets that were fabricated for this study, which mold and materials they were made from and which conditions they were tested for. the sockets were identically aligned in a vertical alignment jig (hosmer, fillauer, chattanooga, united states) using the model patient’s alignment, which was 5 degrees of flexion and 2 degrees of abduction. this alignment was done similarly to previous studies, which do not follow the iso 10328 recommendation that the alignment be set in the “worst condition”.5,6 this decision was made to standardize the process using a realistic alignment for the chosen model shape as this bench alignment is repeatable whereas the specifics of what makes a worse case condition is unspecified and is inconsistent with previous studies. the alignment chosen will allow future tests to be compared to the socket test done in this study. a 5r1 attachment block was used for sockets made for cushion liners, 3 6 s o c k e ts 1 8 s o c k e ts f o r lo c k in g l in e r w it h a d is ta l 4 -h o le p a tt e rn l o c k 6 t h e rm o p la s ti c s o c k e ts 3 tested for condition i (early stance), one at each of p3, p4 and p5 3 tested for condition ii (late stance), one at each of p3, p4 and p5 6 l a m in a te d c o m p o s it e s o c k e ts 3 tested for condition i (early stance), one at each of p3, p4 and p5 3 tested for condition ii (late stance), one at each of p3, p4 and p5 6 3 d p ri n te d p l a s o c k e ts 3 tested for condition i (early stance), one at each of p3, p4 and p5 3 tested for condition ii (late stance), one at each of p3, p4 and p5 1 8 s o c k e ts f o r c u s h io n l in e rs w it h a d is ta l a tt a c h m e n t b lo c k 6 t h e rm o p la s ti c s o c k e ts 3 tested for condition i (early stance), one at each of p3, p4 and p5 3 tested for condition ii (late stance), one at each of p3, p4 and p5 6 l a m in a te d c o m p o s it e s o c k e ts 3 tested for condition i (early stance), one at each of p3, p4 and p5 3 tested for condition ii (late stance), one at each of p3, p4 and p5 6 3 d p ri n te d p l a s o c k e ts 3 tested for condition i (early stance), one at each of p3, p4 and p5 3 tested for condition ii (late stance), one at each of p3, p4 and p5 https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 3 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index as it has been reported to be the most commonly used socket attachment methods in canada.8 the sockets for the locking liners were attached using the distal 4-hole pattern in the lock mechanism. all sockets were then attached to an ottobock (duderstadt, germany) titanium pyramid (5r54), a 23.2 cm aluminum pylon with a titanium connector (2r37) and a titanium tube clamp (4r52), all torqued to manufacturer’s specifications. table 1. processes used to produce sockets. every effort was made to ensure an identical process was followed for each socket of the same material. method thermoplastic laminated composite 3d printed m a te ri a l 12 mm orfitrans stiff (a transparent, rigid and thermoformable styrene copolyester) ½ oz. dacron felt, nyglass, carbon cloth, & resin pla p ro c e s s f o r c u s h io n s o c k e ts blister-formed socket attached 5r1 block using ottobock sealing resin and reinforced it with 3” scotchcasttm circumferencial wrap. laminated 1st stage*1, attached 5r1 block using ottobock sealing resin, laminated 2nd stage*2 print socket using fused deposition modelling on rockstock max v3 printer. attach 5r1 block using ottobock sealing resin and reinforced it with 3” scotchcasttm circumferencial wrap. p ro c e s s f o r l o c k in g s o c k e ts set lock dummy in standard alignment blister-formed socket drilled 4 holes distally for lock installation completed 1 stage lamination*3 drilled 4 holes distally for lock installation print socket using fused deposition modelling on rockstock max v3 printer with lock dummy included distally. *1 layup: 1 layer 1/2oz dacron felt, 2 layers nyglass, 1 layer carbon cloth from proximal trimline to 1½” distal to posterior brim trim line, 2 layers nyglass. *2 layup: 1 layer nyglass, 1 layer carbon clock from proximal socket trimline to 1½” distal to posterior brim trimline and from 2” proximal to the distal end to the distal end of the block, 3 layers of nyglass. *3 1 layer 1/2oz darcron felt, 2 layers nyglass, 1 layer carbon cloth from proximal socket trimline to 1½” distal to posterior brim trimline and from 2” proximal to the distal end to the distal end of the socket, 2 x nyglass, 1 layer carbon cloth (as described above), 4 layers nyglass. test step-up the testing was performed in a tinius olsen universal testing machine with a 2500kg revere load cell (tinius olsen test machine co., horsham, united states). iso 10328 specifies the magnitude of load and where the load should be applied at the top and bottom of the set up for each condition, also called the offsets (table 2).6 a jig was fabricated for these conditions, allowing easy and consistent setup of the socket fixture for each test done. the vertical load was applied using two 19 mm hitch balls adapted to the top and bottom lever of the tinius olsen universal testing machine. to evenly distribute the load through the socket a high-density urethane resin (smooth-casttm 380, smooth-on, macungie, united states) mold of the limb was made. a steel rod was molded into the urethane to generate a better grip between the top jig and the limb mold, using a 5/8 bolt. the setup can be seen in figure 3. table 2. the offset values for the top and bottom load application points for all conditions and levels. the forward direction is equivalent to anterior/posterior on the socket and the outward direction is equivalent to medial/lateral on the socket. figure 3. the experimental set up consisting of the socket and pylon held by a custom-made jig in the tinius olsen universal testing machine. p5 p4 p3 reference plane o ff s e t d ir e c ti o n c o n d it io n i c o n d it io n i i c o n d it io n i c o n d it io n i i c o n d it io n i c o n d it io n i i top forward 82 55 89 51 81 51 outward -79 -40 -74 -44 -85 -49 bottom forward -48 129 -52 124 -58 124 outward 45 -19 39 -22 39 -23 https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 4 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index test procedure in accordance with the load values (table 3) and specifications of the structural testing of lower limb prostheses iso 10328, all sockets were tested for a proof test and ultimate static strength test as this standard specifies. table 3. the static test procedure and load for each condition and level. for each condition, the setting force, proof test and ultimate static test force is applied following the protocol described below. for the proof test, the settling test force was applied for 30 seconds before it was removed and the set up rested at zero load for 30 seconds. the test force was then smoothly increased at a rate between 100250 n/s to the proof test force for 30 seconds before it was removed. all load times were recorded with a stopwatch. the ultimate strength test was conducted for all sockets that passed the proof test. again, the settling force was applied for 30 seconds, the set up rested at zero load for 30 seconds, and the test fore was increased at a rate between 100-250 n/s to the ultimate static test force where it was maintained for 30 seconds. if the set-up had not yet failed, the load was increased until failure. failure was the point at where the system could not support any additional load. the 10-minute wait time between the setting force and the test force specified by iso 10328 was reduced to between 30– 60 seconds.6 this was done as no visible deformation or migration occurred during this period, and as this was a preliminary investigation, it allowed for more expedient testing of the samples. statistical analysis four independent variables were looked at: socket type (cushion sockets and locking sockets), fabrication method (thermoplastic, laminated composite and 3d printed), loading condition (condition i and condition ii), and weight limit (p3, p4 & p5). two dependent variables, “proof test performance” and “ultimate strength test performance” each had two possible outcomes: “pass” and “fail”. statistical analysis (spss-ibm, armonk, usa) for socket type and loading condition were evaluated by fisher’s exact test while fabrication method and weight limit were evaluated by chi-square test. results cushion sockets attached distally via a 5r1 block all 9 sockets passed the ultimate strength test for both condition i and ii (figure 4a&b), however the failure levels and methods varied. for condition i, thermoplastic sockets yielded, laminated sockets cracked up the posterior wall and 3d printed socket broke circumferentially above the scotchcasttm (figure 5). for condition ii, 2/3 set-ups for each of the materials failed because the pylon bent and yielded, often while the socket was left intact (figure 5). figure 4. a (top): for cushion sockets at condition i (early stance phase), all set ups failed above the ultimate strength test (ust) values specified in iso 10328; b (bottom): for cushion sockets at condition ii (late stance phase), all set ups failed above the ultimate strength test values specified in iso 10328. in 2/3 cases, the modular components were the cause of failure. p5 p4 p3 test procedure and test load c o n d it io n i c o n d it io n ii c o n d it io n i c o n d it io n ii c o n d it io n i c o n d it io n ii settling test force (n) 1024 920 944 828 736 638 proof test force (n) 2240 2013 2065 1811 1610 1395 ultimate static test force (n) 4480 4025 4130 3623 3220 2790 https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 5 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index figure 5. typical failure methods for sockets made for cushion liners for the following conditions: (a) thermoplastic sockets at condition i (b) laminated composite sockets at condition i (c) 3d printed pla sockets at condition i (d) sockets of all material types at condition ii. the strength to weight ratios were then compared for all sockets along with the failure methods (table 4 a&b). for condition i, the laminated composites had the highest strength to weight ratios, followed by the thermoplastic sockets and the 3d printed socket. the 3d printed sockets were on average approximately 75% of the weight of thermoplastic sockets and withstood approximately 71% of the force. for condition ii, the strength to weight ratio is less relevant due to the failure methods being in the modular components. locking sockets attached distally via a 4-hole pattern lock all 9 sockets passed the ultimate strength tests at condition i, however, none of the sockets passed the ultimate strength test for condition ii, and one socket didn’t pass the proof test (figure 6. a&b). for condition i, thermoplastic sockets yielded around the lock, laminated socket broke either along the posterior wall or within the lock mechanism, and the 3d printed sockets broke circumferentially around the distal end and split up the sides (figure 7). for condition ii, the thermoplastic sockets yielded around the lock, the laminated sockets’ lock mechanisms broke, and the 3d printed sockets broke circumferentially around the distal end (figure 7). table 4. a: strength to weight ratios of cushion sockets for condition i; b: strength to weight ration of cushion sockets for condition ii. the strength to weight ratios were then compared for all sockets along with the failure methods (table 5 a&b). for condition i, the laminated composites had the highest strength to weight ratios, followed by the 3d printed sockets and the thermoplastic sockets. the 3d printed sockets weighed on average approximately 84% of the weight of thermoplastic sockets but withstood approximately 180% of the force. for condition ii the thermoplastic sockets were slightly stronger than the 3d printed sockets but none of them passed the standard. a: condition i material f o rc e ( n ) s o c k e t w e ig h t (g ) s tr e n g th to w e ig h t p e rc e n ti le (% ) f a ilu re laminated composite 13132 429 30.61 100 crack posterior wall laminated composite 13341 450 29.65 97 material yield anterior proximal gap laminated composite 12113 450 26.92 88 crack posterior wall thermoplastic 12566 709 17.72 58 material yield anterior proximal gap thermoplastic 11608 738 15.73 51 material yield anterior proximal gap thermoplastic 11264 734 15.35 50 material yield anterior proximal gap 3d printed pla 7001 541 12.94 42 circumferential break above scotchcasttm 3d printed pla 6725 542 12.41 41 circumferential break above scotchcasttm 3d printed pla 5107 544 9.39 31 circumferential break above scotchcasttm b: condition ii laminated composite 6505 410 15.87 100 distal attachment screw laminated composite 4581 420 10.91 69 pylon laminated composite 4384 437 10.03 63 pylon 3d printed pla 4707 544 8.65 55 pylon , socket crack posterior thermoplastic 5958 733 8.13 51 attachment 3d printed pla 4355 547 7.96 50 pylon, socket crack posterior 3d printed pla 4143 543 7.63 48 circumferential break above scotchcasttm thermoplastic 4434 733 6.05 38 pylon thermoplastic 4340 736 5.90 37 pylon https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 6 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index figure 6. a (top): for locking sockets at condition i (early stance phase), all of the set ups failed above the ultimate strength test values specified in iso 10328; b (bottom): for locking sockets at condition ii (late stance phase), all the set ups failed below the ultimate strength test values specified in iso 10328. figure 7. typical failure methods for sockets made for locking liners. at condition i: (a) thermoplastic sockets yielded and deformed, (b) all laminated composite sockets failed differently with one socket separating from the pyramid when the lock broke, and (c) all 3d printed pla sockets broke circumferentially at the distal end and up the sides. at condition ii: (d) thermoplastic sockets yielded and deformed and the locks broke, (e) the laminated composite sockets’ lock mechanisms broke and (f) 3d printed pla sockets broke circumferentially at the distal end. table 5. a: strength to weight ration of locking sockets at condition i; b: strength to weight ration of locking sockets at condition ii. there were no significant differences observed between socket types at the proof test however, at the ultimate strength test, 100% of all sockets with cushion liners passed while only 50% of those with locking liners passed the test. fisher’s exact test found a statistically significant association between liner type and ultimate strength test, p=0.001. in looking at the strength of the association, results of a phi test showed a strong association between liner type and ultimate strength test results, φ=0.577, p=0.001. similarly, there were no significant differences observed between condition i and condition ii at the proof test however, at the ultimate strength test, a: condition i material f o rc e ( n ) s o c k e t w e ig h t (g ) s tr e n g th to w e ig h t p e rc e n ti le (% ) f a ilu re laminated composite 11730 256 45.82 100 lock mechanism laminated composite 10058 243 41.39 90 pyramid adaptor laminated composite 10364 252 41.13 90 crack posterior wall 3d printed pla 10925 368 29.69 65 circumferential break distal end 3d printed pla 9355 366 25.56 56 circumferential break distal end 3d printed pla 9197 364 25.27 55 circumferential break distal end thermoplastic 7650 446 17.15 37 material yield proximal anterior gap thermoplastic 6091 431 14.13 31 material yield proximal anterior gap thermoplastic 5241 423 12.39 27 material yield proximal anterior gap b: condition ii laminated composite 3526 249 14.16 100 material yield – lock broken laminated composite 3278 253 12.96 91 material yield – lock broken laminated composite 2818 252 11.18 79 material yield – lock broken thermoplastic 3000 426 7.04 50 material yield around lock thermoplastic 2763 437 6.32 45 material yield around lock thermoplastic 2853 460 6.20 44 material yield around lock 3d printed pla 2243 366 6.13 43 circumferential break around distal end 3d printed pla 2189 367 5.96 42 circumferential break around distal end 3d printed pla 2020 365 5.53 39 circumferential break around distal end https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 7 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index 100% of sockets passed at condition i while 50% of passed at condition ii. results showed a statistically significant strong association between test condition and ultimate strength test results (fisher’s exact p=0.001; φ=0.577, p=0.001) when comparing the ultimate strength test results based on manufacturing methods or weight classification there were no statistically significant differences, however, it is worth noting that 25% of sockets failed for each manufacturing method, all for locking liners at condition ii. further testing may produce more decisive results. discussion this study evaluates the static strength of sockets made using a variety of fabrication techniques, including 3d printing, laminated composites and thermoplastics. it employs the methodology used by previous studies to test prosthetic sockets, outlined in iso 10328. this study expended beyond this methodology as it looked at forces in both early stance phase and late stance phase, which previous studies do not do. sockets made for cushion liners thermoplastic sockets: thermoplastic sockets are used as diagnostic sockets. the transparency of this material allows for visual inspection of the socket environment to guide the prosthetist in adjusting the socket shape. thermoplastic sockets are heavier and have less strength than laminated composite sockets and, when tested to failure did not break catastrophically. a study conducted by mackinnon8 found that thermoplastic sockets attached using resin and scotchcasttm to a 5r1 block failure at condition ii occurred at 4792 n. these results are comparable to the current study which found thermoplastic sockets using the same attachment methods failed, on average, at 4910 n, but with the socket tested to p5 failing at 5958 n. this increased strength could be from a variety of factors such as using a different socket shape, differences in plastic thickness, or differences in the height and thickness of the reinforcement material. laminated composite sockets: definitive sockets are made from laminated composites. in daily clinical practice, laminated sockets do not often break over the typical lifetime of a prosthesis. in this study, laminated composite sockets had the highest strength to weight ratio and withstood the highest force. this was especially true for condition i (at early stance) where the sockets failed at approximately 3 times the iso standard. this strength is dependent on many factor as discussed below.9 two other studies evaluated the strength of laminated composite sockets, for condition ii for people weighing over 100 kg, using a similar experimental set up. the first study found their sockets failed between 1836 – 3160 n with the lamination failing at the pyramid attachment point.7 the second study found that for socket reinforced with carbon weighing between 616 – 795g, failure occurred between 4247– 5663 n.5 different material lay-ups and socket attachment methods were found to increase the strength of laminated composite socket.5,7,9 this study also concluded that modular components began to fail above 5400 n of force.5 the sockets tested at condition ii in the current study, weighed between 410–450 g and broke between 4384 and 6505 n. this is approximately double the load reported by the first study and similar to results in the second study, despite sockets in this study weighing much less. reasons for this include material selection, layer order, laminating protocol and socket attachment methods used. this is to be expected, as studies have reported a large variation in socket strength depending on who manufactures it.9 findings of the second study were supported by this study which found that set-ups failed at the modular components; either because the distal attachment screw sheared or the pylon yielded. the current study indicates that for forces applied at condition ii, an average force of 4800 n resulted in failure of the modular components. further testing is required due to the small sample size. 3d printed sockets: 3d printing technology has been identified as having the potential to benefit the production of prosthetic sockets.3,4,10,11 for example, in the current study, the 3d printed sockets took 9 hours and 9 minutes to print but required much less active time from a technician than traditional manufacturing methods. while 3d printing allows for rapid prototyping of custom designs, decreased manufacturing times and increased opportunities for collaboration, the main limitation continues to be the lack of standardization https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 8 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index and regulation which may place patients at risk of receiving unsafe devices.3,4,12 one way to evaluate the safety of 3d printed sockets is to explore how they compare strength wise to other fabrication methods available. for sockets made for use with cushion liners, this preliminary testing provides evidence that 3d printed sockets are strong enough statically to be used with patients as they passed the standards for all weight limits. however, when tested to failure, they failed at approximately half of the force of traditional manufacturing methods. this is hypothesized to be as a result of the material properties and manufacturing process. while traditional manufacturing methods involve either a solid sheet of plastic, which yields before it breaks, or layers of sheets of reinforcement materials, often braided or weaved for strength, 3d printing deposits material in layers, thus making it inherently weaker. when force was applied, it appeared that the 3d printed material sheared between layers. there are many factors in the printing process and design that may be able to increase the strength of these sockets such as by changing print orientation, infill pattern, adding corrugations, changing material types or using a different type of printer. subsequent work completed by campbell et al. provides preliminary support that for sockets made for cushion liners 10% changes in infill percentage does not affect the strength.13 for condition i (early in stance phase), the sockets failed well above the iso standard, by cracking circumferentially about the scotchcasttm reinforcement. this indicates that the force is being concentrated there, which could be decreased using different manufacturing methods described above. for condition ii (late in stance phase), the modular components failed before the sockets failed. modular components are regularly used in clinical practice without negative consequences. it is likely that since they are breaking before sockets are breaking, 3d sockets will survive the impact put on them statically. another issue raised is that 3d printed sockets break catastrophically, while other manufactured materials yield or tear more slowly. this catastrophic breaking may present dangers to patients who could be injured in this process. additional work is required to further investigate this issue and determine if this drawback can be avoided, as well as to see how this material acts when going through cyclical testing. inherent in rapid prototyping is the adjustability and flexibility in the manufacturing methods – there are infinite designs, material choices and print settings that can be adjusted to influence the final product. as in conventional manufacturing methods, this variability will largely influence how strong sockets are.9 more work is required to evaluate these different parameters and give guidance to which choices result in better outcomes. sockets made for locking liners this study presents some preliminary evidence that the use of cylindrical locks in prostheses should be re-considered. regardless of the manufacturing methods used, the sockets with locks did not pass the iso standard for forces applied at condition ii, and in all cases the material around the lock either yielded or cracked. unless modifications are done to relieve the stress concentration from this point or include additional reinforcement, these sockets may fail when patients are using them. alternatively, other lock mechanisms may be an option as they result in different distal socket shapes which may have less concentrated stress points and may withstand higher forces. this preliminary evidence supports that 3d printed sockets should not be used to create sockets with distal cylindrical locks. limitations balancing the production of clinically-relevant and scientifically sound evidence with the feasibility of completing the research leads to several limitations which need to be addressed. first of all, sockets are not subject to iso 10328 testing. however, as the other components in lower limb prostheses are subject to this standard and as several previous studies5,7,9 employed this methodology, it is reasonable to use 10328 as an evaluation tool for socket strength. the 2006 version of iso 10328 was used as the 2016 version was not yet released at the beginning of testing. the protocol outlined in the standard was followed as closely as possible, however several changes were made in order to allow the results to be compared to other studies and to make it feasible to conduct in a timely and cost-efficient manner. at this time point, only the static portion of the structural tests were conducted due to the length of time required to cyclical testing. however, plans are in place to continue work on cyclical testing after addressing https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 9 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index some of the limitations uncovered through this study. when selecting a model, the standard does not specify a suitable size or shape, so a model was chosen that fulfilled technical limitations and resulted in a more expedient process. the model chosen was slightly smaller than previous studies, but it is a realistic mold, copied from a patient’s everyday prosthesis, and it was consistent across all samples. the alignment for the model was also taken from the patient’s every day alignment, which is a fairly neutral bench alignment. the standard outlines using a worse-case alignment, but as this is not precisely defined, and as all previous studies used a standard bench alignment, a standard bench alignment was used here too. this allows for comparison with other studies and consistency between samples. finally, due to financial, time and resource constraints, two modifications were made to the testing protocol. first, only one sample was tested for each weight limit and condition. while the standard recommends testing a minimum of two samples of each condition, choosing only one sample allowed testing at both early stance and at late stance which had not been completed in any previous study on socket strength. this resulted in new findings and directions for future research to be uncovered. second, the wait time between the test force and the ultimate strength test force was reduced. this significantly reduced the testing time required, allowing for more samples to be tested. other limitations arose from the results of the socket tests. when completing the testing for condition ii, the endoskeleton modular components often failed before socket was affected. while pylons are tested to iso 10328, these components broke prematurely and prevented the specific testing of the socket. in future studies, solid pylons can be used to isolate the force on the socket attachment and evaluate the socket strength more directly. also, while completing testing on sockets made for locking liners, the lock mechanism frequently broke. in future studies, a lock mechanism which does not act as part of the structural attachment to the modular components may result in stronger sockets. future work there is a need for continued work on this topic of 3d printing to support its use in prosthetic fabrication in an evidence-based and safe manner. for static strength testing, future work may include testing larger models with worse-case scenario alignment and larger sample sizes. there is also an endless combination of material choices, design options and 3d print parameters that can be explored. more specifically, the distal attachment could be strengthened, particularly in sockets made for locking liners, to extend the use of 3d printing to locking liners. also, if design or material options could eliminate the catastrophic nature of the 3d printing failure, patient safety would be significantly enhanced and the adoption of this technology would be more widely accepted. beyond static testing, cyclical testing of 3d printed sockets must also be done to complete the testing palate. until information is known on how this material performs over time, clinicians cannot be confident that this manufacturing method will meet the demands of ambulation. future work should focus on expanding the static testing that has been done to cyclical tests in order to present a more complete picture of how this technology will work for patients. in addition to strength, there are many other factors that can be explored including the personnel and material costs of using 3d printing over other manufacturing methods, the ease of fabrication, quality and consistency of devices fabricated, and the methods of introduction of this method into clinical practice. conclusion this study explored the strength of 3d printed prosthetic sockets in comparison with two other techniques that are currently used in clinical practice. it was found that all 3d printed sockets made for use with cushion liners withstood the loads specified by the iso standard. in addition, at terminal stance, in many cases the pylons yielded before the sockets broke. as this is not routinely seen in clinical practice, it provides some evidence that the sockets are stronger than the modular components and therefore statically safe to use on patients. however, one notable limitation to the incorporation of 3d printed sockets into practice is the catastrophic nature of the failure and thus the potential serious risk it can pose to the patient. further evaluation needs to be conducted to explore how 3d printing manufacturing methods can affect the strength of sockets and the nature of the failure. https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index pousett b, lizcano a, raschke s.u. an investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.2. https://doi.org/10.33137/cpoj.v2i1.31008 10 open access pousett et al., the structural strength of transtibial sockets volume 2, issue 1, article no.2, april 2019 https://jps.library.utoronto.ca/index.php/cpoj/index acknowledgements we would like to thank the following people for their contributions to this project: david moe cp(c), daryl murphy rtp(c) and barber prosthetics clinic for all of the clinical expertise, technical expertise and socket manufacturing required for this project; nigel halsted and ernie janzen with bcit make+ for the testing expertise, testing jig design and manufacturing; the bcit school of energy for access to the testing equipment and yvette jones, also with bcit make+, for the statistical analysis. additive orthotics & prosthetics for their expertise with 3d printing sockets and ortoped & ottobock for their generous donations of materials & componentry. declaration of conflicting interests the authors have no conflicts of interest to declare. sources of support materials and components were provided by barber prosthetics clinic, ortoped & ottobock. author contribution • brittany pousett conception and design of the work. supervision of fabrication of sockets. data analysis and interpretation. drafting of the manuscript. • aimee lizcano conception or design of the work. data collection. data analysis and interpretation. drafting of the manuscript. • silvia u raschke canadian supervising academic. conception and design of the work. guided data analysis. critical revision of the manuscript. references 1.herbert n, simpson d, spence wd, ion w. a preliminary investigation into the development of 3-d printing of prosthetic sockets. j rehabil res dev. 2005;42(2):141146. doi:10.1682/jrrd.2004.08.0134. 2.jin y, plott j, chen r, wensman j, & shih a. additive manufacturing of custom orthoses and prostheses–a review. procedia cirp. 2015;35:199–204. doi: 10.1016/j.procir.2015.02.125. 3.rogers b, bosker gw, crawford rh, faustini mc, neptune rr, walden g, gitter aj. advanced trans-tibial socket fabrication using selective laser sintering. prosthetics and orthotics international. 2007 mar;31(1):88100. doi: 10.1080/03093640600983923. 4.diment le, thompson ms, & bergmann jhm. three dimensional printed upper-limb prostheses lack randomised controlled trials: a systematic review. prosthet. orthot. int. 2018;42(1):7-13. doi: 10.1177/0309364617704803. 5.graebner rh, current ta. relative strength of pylon-tosocket attachment systems used in transtibial composite sockets. j prosthetics orthot. 2007;(19):67-74. doi: 10.1097/jpo.0b013e3180cfe8da. 6.international organization for standardization. prosthetics-structural testing of lower-limb prosthesesrequirements and test methods. (iso 10328:2006e); 2006. 7.current ta, kogler gf, barth dg. static structural testing of trans-tibial composite sockets. prosthet orthot int. 1999;23:113-122. doi:10.3109/03093649909071622. 8.mackinnon d. relative strength of common diagnostic pylon-to-socket attachment methods. master’s capstone/thesis, british columbia institute of technology (bcit), 2010. 9.gerschutz mj, haynes ml, nixon d, colvin jm. strength evaluation of prosthetic check sockets, copolymer sockets, and definitive laminated sockets. j rehabil res dev. 2012;49(3):405-426. http://dx.doi.org/10.1682/jrrd.2011.05.0091 10.scott k. dad designs and 3d prints arm for his son. cnn. https://www.cnn.com/2017/11/14/health/ambionicsprosthetic-arm/index.html. published november 24, 2017. 11.byaruhanga c. prosthetic limbs made by 3d printers. bbc news. https://www.bbc.com/news/av/health31151088/prosthetic-limbs-made-by-3d-printers. published 2015. accessed july 19, 2018. 12.ventola cl. medical applications for 3d printing: current and projected uses. p t. 2014;39(10):704-711. http://www.ncbi.nlm.nih.gov/pubmed/25336867. accessed october 14, 2017. 13.campbell l, lau a, pousett b, janzen e, raschke s.u. how infill percentage affects the ultimate strength of 3dprinted transtibial sockets during initial contact. can prosthet orthot j. 2018;1,2. https://doi.org/10.33137/cpoj.v1i2.30843. https://doi.org/10.33137/cpoj.v2i1.31008 https://jps.library.utoronto.ca/index.php/cpoj/issue/view/2195 https://jps.library.utoronto.ca/index.php/cpoj/index http://dx.doi.org/10.1682/jrrd.2011.05.0091 https://www.cnn.com/2017/11/14/health/ambionics-prosthetic-arm/index.html https://www.cnn.com/2017/11/14/health/ambionics-prosthetic-arm/index.html https://www.bbc.com/news/av/health-31151088/prosthetic-limbs-made-by-3d-printers https://www.bbc.com/news/av/health-31151088/prosthetic-limbs-made-by-3d-printers http://www.ncbi.nlm.nih.gov/pubmed/25336867 https://doi.org/10.33137/cpoj.v1i2.30843 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 research article michelini a., sivasambu h., andrysek j. the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced asymmetry. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.6. https://doi.org/10.33137/cpoj.v5i1.36223 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.36223 1 michelini a., sivasambu h., andrysek j. the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced asymmetry. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.6. https://doi.org/10.33137/cpoj.v5i1.36223 research article the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced asymmetry michelini a.1,2 *, sivasambu h.1,2, andrysek j.1,2 1 institute of biomedical engineering, university of toronto, toronto, canada. 2 bloorview research institute, holland bloorview kids rehabilitation hospital, toronto, canada. introduction spatiotemporal gait asymmetry is a condition commonly exhibited in clinical populations with mobility difficulties including individuals with lower limb amputation (lla), parkinson’s disease, and cerebral palsy. gait asymmetries result in atypical biomechanical and walking and loading patterns, and over time, can lead to long-term musculoskeletal issues such as joint degeneration and osteoarthritis.1,2 excessive gait deviations and asymmetry can be attributed to a lack of proper gait training leading to the development of poor gait habits.1 however, there are limitations to conventional in-person gait training sessions with a physiotherapist, such as the cost and accessibility of the service.3 modern approaches and technologies such as virtual reality, rehabilitation video games, and biofeedback (bfb) systems take advantage of motor learning strategies and are promising tools for gait rehabilitation in the clinic and at home.4 open access volume 5, issue 1, article no.6. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: biofeedback (bfb), the practice of providing real-time sensory feedback has been shown to improve gait rehabilitation outcomes. bfb training through rhythmic stimulation has the potential to improve spatiotemporal gait asymmetries while minimizing cognitive load by encouraging a synchronization between the user’s gait cycle and an external rhythm. objective: the purpose of this work was to evaluate if rhythmic stimulation can improve the stance time symmetry ratio (stsr) and to compare vibrotactile to auditory stimulation. gait parameters including velocity, cadence, stride length, double support time, and step length symmetry, were also examined. methodology: an experimental rhythmic stimulation system was developed, and twelve healthy adults (5 males), age 28.42 ± 10.93 years, were recruited to participate in walking trials. a unilateral ankle weight was used to induce a gait asymmetry to simulate asymmetry as commonly exhibited by individuals with lower limb amputation and other clinical disorders. four conditions were evaluated: 1) no ankle weight baseline, 2) ankle weight without rhythmic stimulation, 3) ankle weight + rhythmic vibrotactile stimulation (rvs) using alternating motors and 4) ankle weight + rhythmic auditory stimulation (ras) using a singletone metronome at the participant’s self-selected cadence. findings: as expected the stsr became significantly more asymmetrical with the ankle weight (i.e. induced asymmetry condition). stsr improved significantly with rvs and ras when compared to the ankle weight without rhythmic stimulation. cadence also significantly improved with rvs and ras compared to ankle weight without rhythmic stimulation. with the exception of double support time, the other gait parameters were unchanged from the ankle weight condition. there were no statistically significant differences between rvs and ras. conclusion: this study found that rhythmic stimulation can improve the stsr when an asymmetry is induced. moreover, rvs is at least as effective as auditory stimulation in improving stsr in healthy adults with an induced gait asymmetry. future work should be extended to populations with mobility impairments and outside of laboratory settings. article info received: march 19, 2021 accepted: january 22, 2022 published: february 7, 2022 citation michelini a., sivasambu h., andrysek j. the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weightinduced asymmetry. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.6. https://doi.org/10.33137/cpoj.v5i 1.36223 keywords spatiotemporal gait asymmetry, biofeedback, rehabilitation, entrainment, amputation, rhythmic stimulation, gait * corresponding author jan andrysek, phd bloorview research institute, holland bloorview kids rehabilitation hospital, toronto, canada. e-mail: jandrysek@hollandbloorview.ca orcid id: https://orcid.org/0000-0002-4976-1228 https://doi.org/10.33137/cpoj.v5i1.36223 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i1.36223 https://doi.org/10.33137/cpoj.v5i1.36223 mailto:jandrysek@hollandbloorview.ca https://orcid.org/0000-0002-4976-1228 2 michelini a., sivasambu h., andrysek j. the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced asymmetry. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.6. https://doi.org/10.33137/cpoj.v5i1.36223 issn: 2561-987x rhythmic vibrotactile and auditory biofeedback michelini et al., 2022 cpoj bfb is the practice of providing real-time feedback to an individual based on collected information from that user.5 bfb can be used to supplement traditional gait training using various modalities – most commonly through visual, auditory, and vibrotactile. auditory and vibrotactile feedback modalities are most suited for wearable and field-based applications, however, there is no clear consensus on the most appropriate modality for gait rehabilitation.5 both modalities are commonly utilized as part of sensory augmentation and substitution. specifically, in the case of gait rehabilitation, auditory or tactile stimulation modalities indirectly provide information about gait movements and events. while both modalities act to augment sensory feedback, they do so by utilizing different neural physiology and pathways.6,7 this can manifest into unique responses or levels of biofeedback effectiveness. rhythmic movement interventions are a form of bfb that have been shown to improve automaticity and gait regularity.8 entrainment is the phenomenon whereby two out of phase rhythms synchronize.9 the practice of using entrainment for gait training has been shown to be successful for a variety of populations, where the individual will synchronize their gait cycle (heel strike or toe-off times) to an external beat or tempo.10 this can be accomplished through rhythmic auditory stimulation (ras). ras has been shown to improve cadence and symmetry and can be effective for gait recovery.11 it has also been shown to reduce stride time, swing time, and step time variabilities for individuals with parkinson’s disease and following stroke.12 further potential benefits include increased cadence and gait symmetry.13 for individuals with lla, ras has been shown to decrease gait training times.14 compared to its auditory counterpart, the effects of rhythmic vibrotactile stimulation (rvs) are not as well understood; however, rvs is a promising modality for gait rehabilitation and particularly wearable applications since it does not interfere with the auditory system. rvs has been shown to improve step length, and cadence in patients with parkinson’s disease using vibration motors at the wrist13 and ankle.14 the overall goal of this study was to evaluate and compare the efficacy of vibrotactile and auditory rhythmic stimulation to improve the stance time symmetry ratio (stsr) of ablebodied individuals with induced asymmetries. increased stance time symmetry has been associated with improved gait performance and rehabilitation outcomes in certain patient groups.15-17 secondarily, the study examined other key gait parameters including velocity, cadence, stride length, double support time, and step length symmetry associated with rhythmic stimulation. methodology system instrumentation a wearable microcontroller-based system was developed to provide vibrational stimulation at the user’s preferred cadence and target stsr. rvs was delivered using two 9 mm vibration motors (model 307-103-precision microdrives ltd, london, united kingdom) for a duration of 100 ms. each vibrating motor was supplied with 3.3 v, corresponding to a nominal vibration frequency of 250hz and vibration amplitude of 7.5 g. an arduino uno (arduino, somerville, massachusetts) was used to control the timing of the rvs delivery and was placed on the user’s waist as shown in figure 1 using a velcro waist strap. the system was powered by a single cell 5000 mah lithium-ion battery. a motor was adhered directly to the skin on each side of the user’s lower abdomen as per crea et al.,18 behind the waist strap. recent work has found that higher frequency vibrations (>230 hz), targeting ruffini cylinders and pacinian corpuscles skin mechanoreceptors, increase user detection accuracy and reduce reaction times following vibrotactile stimulation.19,20 rvs alternated between the left and right sides using the two motors as described in figure 2a. ras was delivered using a digital metronome (google, mountain view, california) on a pc speaker loud enough such that the participant could hear throughout the gait laboratory. the auditory tones were delivered using a singular tone for both left and right limbs as described in figure 2b. figure 1: equipment and instrumentation for rvs system. a: setup of the bfb system on a participant; b: microcontroller-based control unit, including the custom electronic board, and power supply; c: vibrating unit (motors) located at the lower abdomen. (a) (c) microcontroller custom electronic board power bank (5 v, 5 ah) vibrating motors ankle weight (b) https://doi.org/10.33137/cpoj.v5i1.36223 3 michelini a., sivasambu h., andrysek j. the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced asymmetry. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.6. https://doi.org/10.33137/cpoj.v5i1.36223 issn: 2561-987x rhythmic vibrotactile and auditory biofeedback michelini et al., 2022 cpoj participants a convenience sample of twelve (n = 12) able-bodied adults were recruited for this study. inclusion criteria included: 1) above the age of 18 years, 2) english speaking, and 3) having no physical or gait-related impairments, ambulation difficulties, or neuro-motor compromises. the study was approved by the research ethics board at holland bloorview hospital, canada. informed written consent was obtained from each participant before commencing. experimental setup and data processing previous research has shown that when using rhythmic cueing to improve gait parameters such as stride length and cadence, it is most effective when the provided tempo of the stimulation is close to the participant’s natural cadence.21,22 for this reason, the cadence was determined by having the participant walk at a self-selected speed without the ankle weight. the tempo of the rvs and ras was set to the identified cadence value at the user’s self-selected baseline speed. to induce asymmetry of gait parameters an ankle weight of 2.27 kg was used; an intermediate value to that used in other studies (1.95 – 3 kg),23,24 placed on the non-dominant leg.25 the ankle weight was placed on the non-dominant leg to compound the asymmetric effect. to determine leg dominance, the participant was asked which leg they use to kick a soccer ball.26 the participant was given five minutes to adjust to the added ankle weight as per smith and martin.23 gait data were collected with the cortex software (motion analysis corporation, santa rosa, california) using a system with 12 cameras, sampled at 200 hz. twenty retroreflective markers were placed following a modified helen hayes lower extremity marker: medial and lateral ankles, toes, heels, tibias, medial and lateral knees, thighs, anterior superior iliac spines, sacral, and right offset.27,28 when the ankle weight was added, the lateral and medial ankle markers were placed on the outside of the ankle weight and in line with the unloaded lateral and medial ankle markers. the motion capture position data were smoothed within the cortex software applying a butterworth low pass filter with a cut-off frequency of 6 hz, as per the study by schreiber and moissenet.29 gait parameters were processed automatically using the cortex software. protocol data for each participant were collected during a single twohour session. the participant was asked to walk at a selfselected speed back and forth along an 8 m walkway located in a gait laboratory. a single walking trial consisted of one pass of the 8 m walkway. five baseline trials were collected. on average, 1-2 full gait cycles were recorded on each pass of this walkway. following the baseline trials, the researcher analyzed one of the trials to determine the participant’s preferred cadence. the participant was then instrumented with the unilateral ankle weight, given 5 minutes to walk and adjust to the weight, and then provided a 5-minute break to avoid fatigue. next, rhythmic stimulation was provided. the order of rvs or ras trials was randomized using simple and balanced randomization through a random number generator (1= rvs first, 2 = ras first). the participant was instructed to walk to the tempo of the rvs or ras, with their heel strike occurring at the time of the stimulus. five minutes of practice with the stimulation was followed by a 5-minute break. subsequently, 5 walking trials with rhythmic stimulation were collected. this process was repeated with the other stimulation modality. outcome measures the primary outcome measure for this experiment was stance time symmetry ratio (stsr), calculated using equation 1, where the limb with the unilateral ankle weight is considered the loaded limb, while the limb without the ankle weight is considered the unloaded limb. stsr was used because of its demonstrated ease of interpretation by the user and the ability to assess gait control through this figure 2: a) rhythmic vibrotactile stimulation delivery; b) rhythmic auditory stimulation delivery. note: hs (heel strike) and to (toeoff) indicate when the user should be in the hs and to portions of the gait cycle, respectively, if following the rhythmic stimulation. 0% 50% 100% 0% 50% 100% 0% 50% 0% 50% 100% 0% 50% 100% 0% 50% a b https://doi.org/10.33137/cpoj.v5i1.36223 4 michelini a., sivasambu h., andrysek j. the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced asymmetry. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.6. https://doi.org/10.33137/cpoj.v5i1.36223 issn: 2561-987x rhythmic vibrotactile and auditory biofeedback michelini et al., 2022 cpoj variable.30 perfect symmetry is equal to a value of 1, while asymmetry is less than or greater than 1. the individual spends more time in the stance portion of the gait cycle on the unloaded limb if the symmetry ratio is less than 1. some deviation around the value of 1 is considered normal. for example, patterson et al. found that for healthy participants, the mean stsr was 1.02 ± 0.02 with an upper 95% confidence interval boundary of 1.05.31 secondary outcome measures included cadence, forward velocity, double support time, step length symmetry ratio (calculated using the same formula as stsr), and stride length. equation (1) 𝑆𝑇𝑆𝑅 = 𝑆𝑡𝑎𝑛𝑐𝑒 𝑇𝑖𝑚𝑒 𝑙𝑜𝑎𝑑𝑒𝑑 𝑙𝑖𝑚𝑏 𝑆𝑡𝑎𝑛𝑐𝑒 𝑇𝑖𝑚𝑒 𝑢𝑛𝑙𝑜𝑎𝑑𝑒𝑑 𝑙𝑖𝑚𝑏 statistical analysis statistical analyses were performed using jmp pro software (statistical discovery, sas, usa). the data were tested for normality using the shapiro-wilk w test for each set (p<0.05). using a repeated measures multivariate analysis of variance (rmanova), the outcome measures were compared among baseline, ankle weight without rhythmic stimulation, rvs, and ras. to account for type i error, a bonferroni correction was applied to the original α value of 0.05. therefore, the significance level of α = 0.05/6 = 0.0083 was used for all statistical tests. the order of rvs and ras was applied in the rmanova as an effect to account for training throughout the experiment. a paired ttest was applied for post hoc analysis. if p<0.0083, we rejected the null hypothesis that: 𝐻𝑜: 𝜇𝑏𝑎𝑠𝑒𝑙𝑖𝑛𝑒 = 𝜇𝑎𝑛𝑘𝑙𝑒 𝑤𝑒𝑖𝑔ℎ𝑡 𝑏𝑎𝑠𝑒𝑙𝑖𝑛𝑒 = 𝜇𝑅𝑉𝑆 = 𝜇𝑅𝐴𝑆. effect sizes were calculated using partial η2 with effect sizes of 0.01, 0.06, and >0.14 considered small, medium, and large, respectively. mauchly’s test of sphericity was used to test for the assumption of sphericity.32 results the participant characteristics are shown in table 1. table 1: participant characteristics. variable range mean ± standard deviation age (years) 23-61 28.4 ± 10.9 height (cm) 167-183 174.6 ± 4.7 weight (kg) 58.5-113 71.6 ± 15.7 calculated cadence (steps/min) 103-118 111.9 ± 4.7 sex: m/f m: 5, f: 7 ankle weight placement: left/right right: 1, left: 11 mauchly’s test of sphericity indicated that the assumption of sphericity had been violated (p<0.05) for cadence [χ2(5) = 21.48, p<0.0001], stride length [χ2(5) = 14.88, p = 0.011], velocity [χ2(5) = 14.66, p = 0.012], and step length ratio [χ2(5) = 19.81, p = 0.0.0014], therefore degrees of freedom were corrected using greenhouse-geisser estimates of sphericity. the rmanova showed significance for stsr [f(3,9) = 55.5, p <0.0001], double support time [f(3,9) = 17.63, p = 0.0004] and cadence [f(1.91, 21.05) = 17.86, p<0.0001], while step length ratio [f(1.43, 15.72) = 0.86, p = 0.41], stride length [f(1.67,18.42) = 0.99, p = 0.38] and velocity [f(1.78,19.56) = 4.45, p = 0.035] were not. the corresponding effect sizes were 0.95, 0.854, 0.731, 0.001, 0.011 and 0.012, respectively. there was no order effect in the experiment. means and standard deviations for the 4 conditions and 6 parameters are found in table 2. based on the post hoc tests, there was a significant decrease in stsr from the no ankle weight baseline to ankle weight without rhythmic stimulation conditions [t(11) = -11.99, p<0.0001]. the total stsr decrease was 0.061 ± 0.018. significant differences were also found between baseline and rvs [t(11) = -11.68, p<0.0001], and baseline and ras conditions [t(11) = -13.09, p<0.0001]. there was also a significant improvement from ankle weight without rhythmic stimulation to rvs condition [t(11) = 4.91, p = 0.005]. further, there were significant differences in two of the secondary outcome measures, including cadence, and double support time (table 2). post hoc analysis showed a significant decrease in cadence occurred from baseline to ankle weight without rhythmic stimulation conditions t(11) = -4.37, p = 0.0011. there was also a significant increase in cadence from ankle weight without rhythmic stimulation to rvs conditions t(11) = 5.45, p = 0.0002, ankle weight without rhythmic stimulation to ras condition t(11) = 5.25, p = 0.0003, and rvs to ras t(11) = 3.01, p = 0.0117. significant differences were found between double support times at baseline and ankle weight without rhythmic stimulation condition t(11) = -5.42, p = 0.0002, baseline and rvs condition t(11) = -6.17, p<0.0001, baseline and ras t(11) = -7.76, p< 0.0001, ankle weight without rhythmic stimulation and rvs t(11) = -3.15, p = 0.0093, and ankle weight without rhythmic stimulation and ras t(11) = -4.14, p = 0.0016. discussion this study has uniquely compared auditory and vibrotactile stimulation and shown that rvs may be at least as effective as its auditory counterpart in improving walking symmetry, as well as cadence while maintaining other gait parameters (with the exception of double support time). this presents an important step in the development of wearable biofeedback systems to augment the gait rehabilitation of individuals with mobility impairments. https://doi.org/10.33137/cpoj.v5i1.36223 5 michelini a., sivasambu h., andrysek j. the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced asymmetry. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.6. https://doi.org/10.33137/cpoj.v5i1.36223 issn: 2561-987x rhythmic vibrotactile and auditory biofeedback michelini et al., 2022 cpoj these findings align with previous studies involving both clinical and healthy populations. in this study the addition of an ankle weight provided a means to simulate asymmetrical gait. without any form of rhythmic stimulation the weight significantly reduced stsr via an elongation of step time of the loaded limb.24,25 rhythmic stimulation was then provided resulting in improved gait symmetry. a similar effect has also been found in clinical populations, namely stroke patients.33-35 although biofeedback significantly improved symmetry in this study, perfect symmetry was not achieved. the inability to achieve a greater change in stsr and/or perfect symmetry is likely related to limitations of the person’s capabilities; in the case of clinical populations, this may, for example, include motor control issues or limited muscle strength, associated with the disability. similarly, the healthy individuals in this study were likely not able to fully overcome the effects of the ankle weight. not only may perfect symmetry be unachievable in some cases, but it may also be undesirable. in the case of someone with a physical or biomechanical asymmetry (i.e. contralateral limbs of different masses such in the case of a lower-limb prosthetic user, or stroke patient with muscle weakness on one side), a slightly asymmetrical gait may present a more optimal walking pattern (i.e. to decrease metabolic cost or increase stability).36 hence, the application of biofeedbackbased gait training must carefully consider the patient’s capabilities as well as rehabilitation goals. both gait velocity and gait symmetry are commonly used to measure overall gait performance as indicators for community ambulation and level of gait control, respectively.31 robinson and smidt note that as gait velocity increases, so does overall mobility.37 in our previous research using corrective biofeedback, symmetry was achieved at the cost of decreased walking speed and cadence;38 in contrast, this experiment demonstrated greater symmetry (using both biofeedback modalities) accompanied by a significant increase in cadence, while other measured spatiotemporal parameters remained unchanged from the baseline condition. the lack of significant change in velocity, stride length and step length symmetry ratio may be a result of the biofeedback targeting temporal rather than spatial aspects of gait. hence vibrotactile rhythmic stimulation, like its auditory counterpart, applied in this experiment has the potential to improve gait more holistically. both stimulation methods (vibrotactile and auditory) produced similar results, and improvements in gait. this was not necessarily an expected finding, since the sensory systems utilize different receptors, neural pathways and processing centers. sigrist et al. has said that auditory feedback is suitable for the perception of temporal information, while haptic feedback is appropriate for the perception of spatial and temporal information.6 moreover, in everyday life, humans are exposed to auditory and vibrotactile rhythmic stimuli differently, hence one might expect that responses would differ also. for example, music is a common stimulus resulting in entrainment and the synchronization to auditory signals.39 entrainment based on somatosensory stimulation on the other hand, is less common in the physical world. hence, one may expect auditory stimuli to be more effectively utilized. this study, however, suggests that the sensory modality may play a minor role, as long as signals are able to be adequately sensed. further, it may be possible that gait performance is more substantially influenced by elements of motor control or even perhaps biomechanics (ability of our muscles to control the movements to overcome the effects of the ankle-weight) rather than the ability to sense and process rhythmic stimulation. future work is needed to better elucidate the neurophysiological mechanisms involved in the utilization of biofeedback in gait. the findings of this experiment may be influenced by several factors. increased double support times were exhibited across all conditions in this study compared to typical gait of 20%.40 this may be due to slower gait or gait table 2: gait parameters under different conditions. no ankle weight baseline ankle weight without rhythmic stimulation ankle weight with rhythmic vibrotactile stimulation (rvs) ankle weight with rhythmic auditory stimulation (ras) (mean ± standard deviation) stance time symmetry ratio 0.999 ± 0.007†‡ 0.938 ± 0.019*‡ 0.952 ± 0.016*† 0.950 ± 0.014* cadence (steps/minute) 111.9 ± 5.2† 107.9 ± 5.5*‡ 111.7 ± 4.4† 112.5 ± 4.3†‡ step length symmetry ratio 0.998 ± 0.025 0.994 ± 0.055 1.006 ± 0.023 1.009 ± 0.019 stride length (cm) 139.6 ± 11.6 140.8 ± 13.9 142.4 ± 15.9 142.8 ± 15.4 velocity (cm/s) 130.1 ± 11.5 126.8 ± 14.9 132.7 ± 16.6 133.9 ± 15.6 double support time (% of the gait cycle) 32.7 ± 1.7†‡ 31.2 ± 2.1*‡ 30.3 ± 2.6*† 30.1 ± 2.2*† * denotes significantly different values than the baseline condition † denotes significantly different values than the ankle weight without rhythmic stimulation condition ‡ denotes significantly different values than the rvs condition https://doi.org/10.33137/cpoj.v5i1.36223 6 michelini a., sivasambu h., andrysek j. the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced asymmetry. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.6. https://doi.org/10.33137/cpoj.v5i1.36223 issn: 2561-987x rhythmic vibrotactile and auditory biofeedback michelini et al., 2022 cpoj compensations that were caused by the test conditions. modality selection for providing feedback through sensory substitution is a continuously developing field as the underlying mechanisms and resulting effectiveness for specific applications are uncovered.7 work performed in the field of balance control found varying effectiveness and latencies in responding to feedback modalities based on age, proposing that decreased residual processing capacity may affect one’s ability to respond to cues from feedback systems.7,41 in case future research confirms auditory and vibrotactile stimulation to produce similar neurophysiological responses, the ultimate decision about which modality to use in biofeedback systems may hinge on other factors such as cost and ease of implementation. study limitations this study has several limitations. one limitation of this study is that the sound from the motors was not controlled for in this experiment. one study that used rhythmic haptic stimulation had the participants wear headphones with white noise so that they would avoid entrainment with the sound of the vibrations and external stimuli.42 however, self-generated auditory feedback such as footsteps when walking is an important factor when controlling spatial and temporal parameters,43 therefore headphones with white noise were not used to mask the sounds from the vibrotactile stimulation in our experiment. additionally, the mass of the ankle weight used for all participants was equal regardless of body mass index, leg strength or other factors. in future work the ankle weight should be adjusted based on the participant’s characteristics to achieve a similarly difficult experience for all subjects. opportunities for future research future experiments should also collect and analyze kinematic data, which would have been useful in identifying any further compensatory mechanisms that the individual exhibited. future work should provide more than one gait training session and assess the retention values and longterm efficacy of rvs and ras. in terms of prototype development, testing of the rvs system should be conducted outside of controlled settings to better characterize aspects related to cognitive loading and impacts of environmental factors on the user’s ability to effectively use the system. although it was important to first test this system on ablebodied adults with an induced asymmetry, future work should evaluate the effectiveness of rvs and ras on other clinical populations, such as individuals with lla. with clinical populations, other therapy goals must be addressed before and during gait training such as range of motion, muscle strength, stability, and proprioception. further, studies are needed to inform the patient demographics that may benefit from the biofeedback system. not all patients may be able to utilize or appropriately respond to biofeedback, and in some cases targeting gait improvements may not align with or be a rehabilitation goal. conclusion this study has shown that both rhythmic vibrational stimulation and rhythmic auditory stimulation can effectively improve walking asymmetry induced by the addition of an ankle weight. in addition to improving stance time symmetry ratio, other important aspects of gait such as cadence were preserved. establishing the viability of vibrotactile based gait training and bfb systems is an important step in developing technologies and feedback modalities for use outside of clinical settings where auditory feedback may not be appropriate. acknowledgements the authors wish to thank firdous hadj-moussa for her support in reviewing and editing the manuscript. declaration of conflicting interests contents from this manuscript were part of a master’s thesis. the authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. author contribution alexandria michelini: conceptualization, methodology, validation, formal analysis, investigation, writing original draft, writing/review and editing, visualization. harry sivasambu: validation, formal analysis, investigation, writing/review and editing, visualization. jan andrysek: supervision, conceptualization, methodology, investigation, writing/review and editing. sources of support the project was supported by ontario graduate scholarship and by nserc crd (crdpj 491125). ethical approval the study was approved by the research ethics board at holland bloorview hospital, canada. informed written consent was obtained from each participant before commencing. references 1.gailey r. review of secondary physical conditions associated with lower-limb amputation and long-term prosthesis 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comparison with a modified helen hayes set. gait posture. 2009; 30:173–80. doi:10.1016/j.gaitpost.2009.04.004 28.kadaba m, ramakrishnan h, wootten m. measurement of lower extremity kinematics during level walking. j orthopeadic res. 1990; 8:383–92. doi:10.1002/jor.1100080310 29.schreiber c, moissenet f. a multimodal dataset of human gait at different walking speeds established on injury-free adult participants. sci data. 2019; 6:111. doi:10.1038/s41597-0190124-4 30.patterson kk, gage wh, brooks d, black se, mcilroy we. evaluation of gait symmetry after stroke: a comparison of current methods and recommendations for standardization. gait posture. 2010; 31:241–6. doi:10.1016/j.gaitpost.2009.10.014 31.patterson kk, nadkarni nk, black se, mcilroy we. gait symmetry and velocity differ in their relationship to age. gait posture. 2012; 35:590–4. doi:10.1016/j.gaitpost.2011.11.030 https://doi.org/10.33137/cpoj.v5i1.36223 8 michelini a., sivasambu h., andrysek j. the short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced asymmetry. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.6. https://doi.org/10.33137/cpoj.v5i1.36223 issn: 2561-987x rhythmic vibrotactile and auditory biofeedback michelini et al., 2022 cpoj 32.armstrong ra. recommendations for analysis of repeated measures designs: testing and correcting for sphericity and use of manova and mixed model analysis. ophthalmic and physiological optics. 2017; 37:585–93. doi:10.1111/opo.12399 33.georgiou t. rhythmic haptic cueing for gait rehabilitation of hemiparetic stroke and brain injury survivors. open university. 2018. doi: 10.21954/ou.ro.0000dabf 34.lee s, lee k, song c. gait training with bilateral rhythmic auditory stimulation in stroke patients: a randomized controlled trial. brain sci. 2018; 8:164. doi:10.3390/brainsci8090164 35.cha y, kim y, chung y. immediate effects of rhythmic auditory stimulation with tempo changes on gait in stroke patients. j phys ther sci. 2014; 26:479–82. doi:10.1589/jpts.26.479 36.roemmich rt, leech ka, gonzalez aj, bastian aj. trading symmetry for energy cost during walking in healthy adults and persons poststroke. neurorehabil neural repair. 2019; 33:602–13. doi:10.1177/1545968319855028 37.robinson jl, smidt gl. quantitative gait evaluation in the clinic. physi ther. 1981; 61:351–3. doi:10.1093/ptj/61.3.351 38.escamilla-nunez r, andrysek j. exploration of vibrotactile biofeedback strategies to modulate spatiotemporal gait asymmetry of individuals with lower-limb amputation. can prosthet orthot j. 2022; 5(1). doi:10.33137/cpoj.v5i1.36744 39.thaut mh, mcintosh gc, prassas sg, rice rr. effect of rhythmic auditory cuing on temporal stride parameters and emg . patterns in gait of stroke patients. neurorehabil neural repair. 1993; 7(1):9-16. doi: 10.1177/136140969300700103 40.levine d, richards j, whittle mw. whittle's gait analysis. elsevier health sciences; 2012. available from: https://www.elsevier.com/books/whittles-gait-analysis/levine/9780-7020-4265-2 41.lin c-c, whitney sl, loughlin pj, furman jm, redfern ms, sienko kh, et al. the effect of age on postural and cognitive task performance while using vibrotactile feedback. j neurophys. 2015; 113:2127–36. doi:10.1152/jn.00083.2014 42.rossi s, lisini baldi t, aggravi m, ulivelli m, cioncoloni d, niccolini v, et al. wearable haptic anklets for gait and freezing improvement in parkinson’s disease: a proof-of-concept study. neurol sci. 2020; 41:3643–51. doi:10.1007/s10072-020-04485-4 43.cornwell t, woodward j, wu m, jackson b, souza p, siegel j, et al. walking with ears: altered auditory feedback impacts gait step length in older adults. front sports act living. 2020; 2:1–11. doi:10.3389/fspor.2020.00038 https://doi.org/10.33137/cpoj.v5i1.36223 https://www.elsevier.com/books/whittles-gait-analysis/levine/978-0-7020-4265-2 https://www.elsevier.com/books/whittles-gait-analysis/levine/978-0-7020-4265-2 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 editorials raschke s.u. editorial opinion: value within the prosthetic and orthotic provision process. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.9. https://doi.org/10.33137/cpoj.v5i1.38442 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.38442 1 raschke s.u. editorial opinion: value within the prosthetic and orthotic provision process. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.9. https://doi.org/10.33137/cpoj.v5i1.38442 editorials editorial opinion: value within the prosthetic and orthotic provision process raschke s.u. * british columbia institute of technology (bcit), 3700 willingdon avenue, burnaby, british columbia, canada. the recent special edition of the canadian prosthetics and orthotics journal focused on the theme of health economics in prosthetics and orthotics, highlighting some of the complexities associated with providing optimal solutions to the end-users of prosthetic and orthotic devices. many people enter the field of prosthetics and orthotics with the desire to connect with and help people, but the underlying reality is that this desire will always be fiscally constrained. for his reason, it is essential to be able to critically analyse one’s work from a cost: benefit perspective and to be able to define and communicate the value of that work to payors whether one works on the clinical or the engineering side of the sector. an underlying theme in the special edition was the significant changes in practices that had emerged once payors began linking reimbursement to the presentation of objective outcome measures a decade ago. at that time prosthetists and orthotists were increasingly required to present objective criteria to communicate and to justify their component and device choices if they wished to be reimbursed. this was a significant shift in the practice paradigm, as previously measurement activities had been limited to device production and fitting related tasks. the response to this new requirement was a palette of outcome measures developed and validated by prosthetic and orthotic researchers for use in a clinical setting. these measures allowed the quantification and tracking of typical rehabilitation outcomes such as mobility, function, activity levels and pain, along with dimensions intended to capture client satisfaction levels,1 allowing prosthetists and orthotists to meet payor requirements. these measures also gave prosthetists and orthotists fluency in the objective language of the medical and scientific communities, allowing them to begin to articulate the previously undocumented interactions with their clients that go beyond the “simple” provision of a device and bring “added value” to the provision process. the adoption of an objectively anchored clinical practice model helped make visible what had previously been invisible. at the same time that payors were compelling clinically facing providers to justify their provision decisions, a related pressure was building upstream, at the technical development level, where payors began to query the costs of new technology solutions. here the critical question was: what significant, measurable value does more complex, and typically more expensive, technology bring? the classic approach to answering this question, much as a new pharmacological intervention would be evaluated, is an evidence based medicine (ebm) approach which became the gold standard in the 1990’s. ebm relies on random clinical trials (rcts) to generate large data sets from which criteria such as minimum clinically important differences (mcid) and dosing can be generated to guide policy and funding decisions. unfortunately, it is not open access volume 5, issue 1, article no.9. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract this editorial presents an overview of the uptake of clinical outcome measures in the prosthetics and orthotics sector and considers how the use of objective measures contribute to demonstrating value provided. a decade ago, payors began to demand objective data to document costs vs. benefits from prosthetic and orthotic providers. the speed with which the sector responded to help develop measures and to begin to integrate them into practice is remarkable. this suggests an encouraging resilience and ability to adapt on the part of the sector as other trends such as values-based health care emerge to challenge the sector. citation raschke s.u. editorial opinion: value within the prosthetic and orthotic provision process. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.9. https://doi.org/10.33137/cpoj.v5i1.38442 keywords orthosis, prosthesis, health economics, prosthetics, orthotics, funding, outcome measures * corresponding author silvia ursula raschke, phd, editor-in-chief british columbia institute of technology (bcit), 3700 willingdon avenue, burnaby, british columbia, canada. e-mail: silvia_raschke@bcit.ca orcid id: https://orcid.org/0000-0001-7964-4295 https://doi.org/10.33137/cpoj.v5i1.38442 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i1.38442 mailto:silvia_raschke@bcit.ca https://orcid.org/0000-0001-7964-4295 2 raschke s.u. editorial opinion: value within the prosthetic and orthotic provision process. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.9. https://doi.org/10.33137/cpoj.v5i1.38442 issn: 2561-987x value within the prosthetic and orthotic provision process raschke s.u, 2022 cpoj possible to carry out classic rcts in the prosthetics and orthotics sector due to small patient populations, the high costs of such studies and the technical challenges of setting up double blinded study designs, which are the gold standard for ebm models. instead, prosthetics and orthotics focused engineers and researchers turned to small-n research designs2 (e.g. multiple baseline, cross-over, repeated measures, singleblinded, etc.) to compare classes of componentry, (i.e. microprocessor vs hydraulic controlled knees or energy storing vs no energy storing prosthetic feet) and results indicated that class of component chosen can lead to measurable differences along a range of dimensions.3,4 through this concentrated, two-pronged research effort spanning clinical aspects and engineering technology, the prosthetics and orthotics sector has been able to transition from an unscientific, artisan-based practice to adopting objective, data-based ways of thinking in a period of ten short years. this is quite an accomplishment. both clinically focused and technology evaluation research studies continue to be done and there is a growing knowledge base indicating that prosthetic and orthotic technology and interventions create measurable changes and experiences for the users of the devices. as health care continues to be rationalized, the next emerging stage in health care policy and decision making is trending toward a values based health care (vbhc) model, which seeks to link funding to outcomes.5 this is based on emerging belief in the business and policy press that the prevalent pathways for funding health care based on fee for service, device or process do not necessarily lead to the best or most efficient health care outcomes.6,7 vbhc advocates for decision making processes negotiates a compromise between balancing genomic-biomedicalbiomechanical aspects of an individual alongside psychosocial and behavioural characteristics, with some consideration of what outcomes matter most to the individual. the model embodies lofty ideals and will be challenging to implement. determining what treatment goals and objectives are optimal for any given situation will require negotiation and sensitivity as “optimal” or “desired” as defined by one stakeholder vs another will often be in conflict with each other.8 achieving this balance between stakeholders, including individual patients, will take considerable time and effort. further complicating this shift is the lack of transparency and consistency from payors as to what measures and evidence are acceptable and deemed adequate for the existing reimbursement models, creating high levels of confusion and frustration with the processes. vbhc will allow for a much denser data sets to be collected along an expanded number of domains. how this data is to be organized, evaluated and weighted in a timely and fair manner is one of the critical questions that must be answered and those answers must be clear. in reimbursement processes already burdened by a lack of clarity, it will be necessary for payors to work with the sector to establish clear and stable goalposts in the various domains in which data will be collected, if this approach is to be successful. were does this new trend leave the prosthetics and orthotics sector? having navigated the past decade amazingly well, my sense is that the sector is in good shape, but with one critical caveat. a decade ago, payors began to require objective outcome measures at a time where few such measure existed and were never used in reporting, challenged the prosthetics and orthotics sector to objectively communicate the value they bring. this externally applied pressure led to unprecedented collaboration between clinicians, researchers and professional organizations who rose to the challenge collectively to create astonishing changes in opinions, attitude and practices. the result is the creation of a value focused lens that has become baked into the sector. the transition has been stressful and disruptive because it was driven by outside forces as opposed to being internally motivated. considering at where the sector was a decade ago, the transformation is astounding and offers hope. i see a maturity and confidence in the sector that was not present even 15 short years ago. i believe this comes in large part because, for the first time in the history, the sector has had to take a hard, critical look at what they do, why they do it and what value they create and found, perhaps to the surprise of some, that value could be objectively demonstrated. this process allowed the sector to deconstruct the myth of the “magic in the hands”9 of the clinician and replaced it with a genuine and professional identity, expressed in the common language of science. the caveat is that, the cascade of next generation health care technology that is now entering the market will create additional, exponential pressures on the sector. keeping up with, integrating and mastering this technology will require an ongoing, energetic response. there no time for the prosthetics and orthotics sector to sit back, catch its breath and enjoy the past decade’s successes. instead, effort needs to be scaled up further with respect to building knowledge and expertise in measuring and communicating value. the future is daunting, but looking back at what has been achieved over the past decade, i believe the sector has successfully created an objectively anchored foundation which will serve it well when navigating what will continue to be uncertain waters. acknowledgements none. declaration of conflicting interests i have no conflicts to interest to declare. https://doi.org/10.33137/cpoj.v5i1.38442 3 raschke s.u. editorial opinion: value within the prosthetic and orthotic provision process. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.9. https://doi.org/10.33137/cpoj.v5i1.38442 issn: 2561-987x value within the prosthetic and orthotic provision process raschke s.u, 2022 cpoj sources of support none. references 1.ramstrand n, phillip m. stevens pm. clinical outcome measures to evaluate the effects of orthotic management post-stroke: a systematic review. disabil rehabil. 2021; 12:1-20. doi:10.1080/ 09638288.2020.1859630 2.graham je, karmarkar am, ottenbacher kj. 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ca, wilson mg. rapid synthesis: examining the effects of value-based physician payment models [internet]. hamilton, canada: mcmaster health forum, 2017; [cited 11 april 2022]. available at: https://www.mcmasterforum.org/docs/defaultsource/product-documents/rapid-responses/examining-theeffects-of-value-based-physician-payment-models.pdf?sfvrsn=2 8.marzorati c, pravettoni g. value as the key concept in the health care system: how it has influenced medical practice and clinical decision-making processes. j multidiscip healthc. 2017; 10, 101– 106. doi:10.2147/jmdh.s122383 9.seibt, d. the sociomaterial construction of users: 3d printing and the digitalization of the prosthetics industry. [in press 2022] london: routledge. https://doi.org/10.33137/cpoj.v5i1.38442 https://doi.org/10.1080/09638288.2020.1859630 https://doi.org/10.1080/09638288.2020.1859630 https://doi.org/10.1186/s12984-018-0405-8 https://doi.org/10.1371/journal.pone.0202884 https://hbr.org/2011/09/how-to-solve-the-cost-crisis-in-health-care https://www.mcmasterforum.org/docs/default-source/product-documents/rapid-responses/examining-the-effects-of-value-based-physician-payment-models.pdf?sfvrsn=2 https://www.mcmasterforum.org/docs/default-source/product-documents/rapid-responses/examining-the-effects-of-value-based-physician-payment-models.pdf?sfvrsn=2 https://www.mcmasterforum.org/docs/default-source/product-documents/rapid-responses/examining-the-effects-of-value-based-physician-payment-models.pdf?sfvrsn=2 https://doi.org/10.2147/jmdh.s122383 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives klenow td, schulz j. adjustable-volume prosthetic sockets: market overview and value propositions. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.17. https://doi.org/10.33137/cpoj.v4i2.35208 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.35208 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 klenow td, schulz j. adjustable-volume prosthetic sockets: market overview and value propositions. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.17. https://doi.org/10.33137/cpoj.v4i2.35208 stakeholder perspectives adjustable-volume prosthetic sockets: market overview and value propositions klenow td.1 *, schulz j.2 1 martin bionics clinical care, fort myers, florida, usa. 2 martin bionics innovations, oklahoma city, oklahoma, usa. introduction the human-device interface, referred to clinically as the socket, is commonly considered to be the most important part of a prosthesis.1-6 it is also the most problematic, however, as lack of socket fit is a commonly reported issue among end-users.5 since the socket is the only customfabricated part of the prosthesis, it’s replacement represents the largest time commitment to the patient.1,7 approximately 90% of amputations occur secondary to diabetes and vascular disorders which leads to complex clinical presentations in much of the population.4,8 vascular compromise amplifies fluid retention difficulties and even small changes in limb volume can lead to socket fit issues.9 open access volume 4, issue 2, article no.17. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract the prosthetic socket is commonly considered to be the most important part of the prosthesis and lack of fit can lead to skin breakdown, reduction in wear, reduction in activity, and consequential deleterious health effects. furthermore, approximately 90% of amputations are due to a vascular etiology, which affect fluid retention regularity, and even small limb volume fluctuations can lead to lack of fit. adjustability in the socket volume has been suggested as a potential solution to common fit issues but has lacked market penetration mostly due to lack of reimbursement. despite this there are several adjustable-volume sockets emerging on the market today including prefabricated, modular, custom with adjustable-volume component, custom with adjustable-volume feature, and adjustable-hybrid sockets. prefabricated sockets are mass produced in common sizes and fit directly to the patient by a prosthetist using pad kits, boa dials, or straps. modular sockets are assembled to a patient or model with panels or struts attached to an adjustable base. custom sockets with adjustable-volume elements are traditionally-fabricated sockets made to a model of a patient’s limb with a volume-adjustable component added or volumeadjustable feature built in. custom-hybrid sockets are made custom to a model of the patient’s limb and incorporate several aspects of the previous socket types and include some radically-unique design aspects which cannot be limited to one category. these adjustable-volume sockets offer several advantages to traditional rigid-volume sockets for the patient, prosthetist, and providing clinic. the microadjustability for the patient allows them to alter fit without removing the socket, maintaining a more intimate fit throughout the day than traditional sockets. the macro-adjustability for the prosthetist allows for increased options for fit customization including the ability to reverse or undo changes without necessarily re-making the socket. this allows for the most optimal fit for the patient. adjustable volume also present efficiencies in the fitting process by simplifying or eliminating steps including residual limb shape capture, form modification, diagnostic fabrication, iterative alteration, and definitive fabrication with the different socket types affecting different steps. due to these factors, adjustable-volume sockets have disrupted the market to the point where reimbursement reform is needed including additional l-codes in the united states and fee-for-service or fee-for-outcome associated with prosthetic follow-up care. prosthetic care should also be separated from durable medical equipment to allow for alternative reimbursement models. as reimbursement adapts prosthetists must adapt correspondingly to differentiate their skillset from other allied health providers including incorporating more objective methods to show superior care outcomes. this adaptation should include a continued push for state and municipal licensure of prosthetists. citation klenow td, schulz j. adjustablevolume prosthetic sockets: market overview and value propositions. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.17 https://doi.org/10.33137/cpoj.v4i2. 35208 keywords innovation, interface, amputation, limb loss, rehabilitation, modular, prosthetic sockets, prosthetics, medical equipment * corresponding author tyler d. klenow, mspo, mba, clpo, faaop martin bionics clinical care e-mail: tyler.klenow@martinbionics.com orcid id: https://orcid.org/0000-0002-6372-2241 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.35208 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.35208 https://doi.org/10.33137/cpoj.v4i2.35208 mailto:tyler.klenow@martinbionics.com https://orcid.org/0000-0002-6372-2241 2 klenow td, schulz j. adjustable-volume prosthetic sockets: market overview and value propositions. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.17. https://doi.org/10.33137/cpoj.v4i2.35208 issn: 2561-987x adjustable-volume prosthetic sockets klenow & schulz. 2021 cpoj special s p e c ia l i s s u e lack of socket fit can lead to pain, discomfort, skin irritation and breakdown, subsequent prosthetic abandonment, and therefore activity reduction, reduced social participation, psychosocial problems, and deleterious health effects due to inactivity.2-8 further, only 50% of individuals with amputation receive a prosthesis initially and 11-22% of patients abandon their prosthesis at one year.10 reamputation and mortality rates surrounding amputation also remain remarkably high thereafter.4,11 these pervasive issues, described above, among the patient population have stimulated several innovations in interface design over the past decade.5,9 a notable innovation is the introduction of additive manufacturing, or 3d-printing, to prosthetic socket fabrication.12 3d-printed sockets offer an improved array of material selection, textured finishes, and elasticity. they also offer new design elements as wall thicknesses can be increased in areas where more structural support is required and decreased where more flexibility is desired. with all the benefits inherent in 3d-printed sockets, they still rely on traditional methods to accommodate residual limb volume changes.8,9 therefore, additive manufacturing alone does not adequately address residual limb fluid dynamics and associated socket fit issues over time. adjustable sockets are designed as an innovation to provide on-demand micro-adjustability to the patient and/or macroadjustability to the prosthetist. micro-adjustability is a socket feature which allows the patient to accommodate diurnal residual limb volume fluctuation without needing to remove the socket to implement a traditional volume management strategy. macro-adjustability is a socket feature which allows the prosthetist to accommodate large physiological changes without necessarily replacing the entire socket or modifying the physical socket structure. adjustability has been stated as a desire for patients and as a potential solution to socket fit issues for several years, but market penetration for adjustable sockets in clinical prosthetics has been limited primarily due to lack of reimbursement.2 adjustable-volume sockets present increased options for customization to the patient, present efficiencies during the fitting process, and allow for prolonged maintenance of fit compared to rigid-volume sockets.13 while there are several types of adjustable-volume sockets available on the market they are commonly omitted from literature reviews on socket design categorically.2,3,14,15 therefore, the purpose of this article is to provide a market overview of adjustable-volume sockets and present their value proposition for end-users and potential providing clinics. market overview there are three major categories of adjustable-volume sockets available on the market today: prefabricated, modular, and custom sockets with adjustable elements (figure 1). prefabricated sockets are ordered by generic size from a supplier and individually fit to the patient by a skilled practitioner. these sockets must be individualized and fit in real-time with the patient and must be trimmed, bent, molded (with or without heat), padded, or otherwise modified resulting in alterations beyond minimal selfadjustment. prefabricated sockets are often bivalve in design and utilize an adjustable closure mechanism such as a cable and dial, toggle latch, ratchet straps, hook and loop velcro, or similar derivative. these sockets often incorporate locking or anatomical suspension. they may or may not have additional adjustable elements. notable prefabricated sockets include the varos socket from ottobock [duderstadt, germany], connect® tf from össur [reykjavic, iceland], and the ifit prosthetics [pewaukee, wi, usa] system. figure 1: examples of prefabricated, modular, custom with adjustable element, and custom-hybrid adjustable-volume sockets. left to right: ottobock varos, lim innovations infinite tf, click medical revofit, martin bionics socket-less socket. modular sockets are ordered as a set of several prefabricated parts and assembled directly to the patient or a model of the patient’s limb by a skilled practitioner. the process typically includes affixing generically-sized struts or panels to a common base with many possible configuration options. the struts or panels must be trimmed, bent, molded (with or without heat), or otherwise modified resulting in alterations beyond minimal self-adjustment to achieve an individual fit for the patient. circumferential pressure and biomechanical control are then attained through some adjustable closure mechanism including ratchet straps, hook and loop velcro, or similar derivative. they often use locking suspension but can be suspended via suction in some arrangements. the most notable modular system was the infinite socket™ line by lim innovations [san francisco, ca, usa].5 the third form of adjustable sockets are custom sockets with adjustable elements. these fully-laminated sockets are fit to a model of a patient’s limb with one or more adjustable elements added or fabricated in. these can include integrated adjustable features such as the tensioning cable with floating panel or ratchet straps which apply or release pressure to a cut-out or flexible portion of the socket. addition of these adjustable socket features requires alterations in socket fabrication or disruption to the https://doi.org/10.33137/cpoj.v4i2.35208 https://shop.ottobock.us/prosthetics/lower-limb-prosthetics/socket-technologies-liners/varos/p/5a60~5r-m https://www.ossur.com/en-us/prosthetics/sockets/connect-tf https://www.ifitprosthetics.com/ https://shop.ottobock.us/prosthetics/lower-limb-prosthetics/socket-technologies-liners/varos/p/5a60~5r-m https://www.liminnovations.com/ https://clickmedical.co/ https://clickmedical.co/ https://martinbionics.com/ 3 klenow td, schulz j. adjustable-volume prosthetic sockets: market overview and value propositions. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.17. https://doi.org/10.33137/cpoj.v4i2.35208 issn: 2561-987x adjustable-volume prosthetic sockets klenow & schulz. 2021 cpoj special s p e c ia l i s s u e traditional physical structure of sockets. notable adjustable socket features are the revofit™ by click medical [steamboat springs, co, usa] and quatro™ socket by quorum prosthetics [windsor, co, usa].5 adjustable components are separately manufactured items added to the custom socket following the fitting process, or which alter the process only slightly. these components include air or fluid bladders such as the former simbex [lebanon, nh, usa] active contact system or prosthetic concepts [little rock, ar, usa] pneu-fit™ system.9 an additional form of adjustable-volume socket, the customhybrid adjustable socket, contains major attributes of the previous three types. custom-hybrid sockets differentiate themselves, as they utilize some other radically-unique design aspects to provide micro-adjustability to the patient and macro-adjustability to the prosthetist. these sockets are justly custom as they can only be fabricated from a model of the patient’s residual limb. they are hallmarked by removal of large portions of the conventional customlaminated socket and replacement of foundational, key socket elements with truly flexible materials. custom-hybrid designs alter traditional mechanical properties of rigid frames and flexible inner sockets in exchange for increased customization, flexibility, and adjustability. these adjustability options are presented both during and after the initial fitting process. the most notable custom-hybrid adjustable systems include the socket-less™ socket system by martin bionics [oklahoma city, ok, usa] and the sail socket by cj socket technologies [beverly, ma, usa].5 the martin bionics socket-less socket™ system replaces most of the conventional, rigid-volume socket with conforming materials which contour to the residual limb, providing a hammock-like fit. the inner socket is replaced with custom-configurable parts consisting of flexible, injection-molded plastic straps, adjustable webbing straps, thermoplastic and metal struts, and micro-adjustable closure mechanisms. these parts can be assembled in combination with each other to create a customized fit. the unique design of the socket-less socket™ allows for numerous configuration options for a wide variety of patient and limb types enabling macro-adjustability by the prosthetist and micro-adjustability by the patient. the martin bionics systems are available for all major amputation levels. all transfemoral (tf) applications utilize an adjustable swingbrim™ which replaces the conventional rigid brim with a webbing-based conforming brim, thereby eliminating rigid contact at the ischial seat. a version called the bikini socket™, which utilizes martin bionics’ iliac crest stabilizers™ and ratchet closures, also exists for hip disarticulation and hemipelvectomy levels. the socketless™ designs have many ancillary benefits reported by martin bionics including improved comfort, breathability, range of motion, restored muscular activation in the residual limb, and reduced heat retention compared to rigid-volume sockets. another custom-hybrid adjustable system is the cj sail socket. this system replaces the traditional flexible inner socket with a textile sail piece which has integrated velcro closures. the sail is typically affixed to one side of a custom socket shell with rivets and the adjustable straps attach to the other side with chafes. the sail socket is available for most major amputations levels and the tf systems are mostly sub-ischial. value proposition • end-users adjustable-volume sockets are designed to accommodate a larger range of residual limb volumes from baseline than rigid-volume sockets.13 the solution to diurnal volume fluctuation in most traditional systems, which is typically in the form of limb volume loss with prolonged daily wear, is to add prosthetic socks to fill the resultant voids.8,9 this requires the user to fully remove the prosthesis which is inconvenient at best. this may occur several times daily resulting in substantial time lost. on the other hand, patients will often avoid going through the process of doffing the prosthesis to change socks to save time and convenience. this doffing avoidance exacerbates fit issues and can cause damage to the residual limb over time. options are more limited in rigid-volume sockets when the volume of the residual limb increases due to edema, weight gain, or some other physiological factor.16 systems with a flexible inner socket and rigid frame can allow for the flexible inner socket to be removed to reveal an increased socket volume.17 patients then add socks, or prosthetists can add pads, to restore fit intimacy. this situation is considered suboptimal, as the benefits of the flexible inner socket are lost and socket design is compromised, unless previously anticipated. further, sockets are not always fabricated with a flexible inner socket or one that can be removed. since the volume accommodation strategies of adjustablevolume sockets are easier for the patient to make, typically through clothing or discretely, they are more likely to be implemented. this can lead to longer durations of optimal fit, increased wear time, and increased physical activity. increased wear leads to more stable limb volumes and accelerated maturation as well.8 this means adjustablevolume sockets are not only able to accommodate residual limbs with frequent volume changes but may also reduce volume fluctuation over time. therefore, adjustable-volume sockets present an opportunity for a short-term and longterm solution to volume fluctuation. independently of this effect, adjustable-volume systems provide a potential solution to long-term volume fluctuation in that the socket volume can be adjusted to the user through adjustment of components or features without necessarily fabricating a new socket. therefore, the patient would not have to commit to the time required for a replacement socket fitting and would reduce costs through reduced payments or coinsurance. https://doi.org/10.33137/cpoj.v4i2.35208 https://clickmedical.co/ https://opquorum.com/programs/ 4 klenow td, schulz j. adjustable-volume prosthetic sockets: market overview and value propositions. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.17. https://doi.org/10.33137/cpoj.v4i2.35208 issn: 2561-987x adjustable-volume prosthetic sockets klenow & schulz. 2021 cpoj special s p e c ia l i s s u e • clinics rigid-volume sockets are currently fit through some form of residual limb shape capture, form modification, diagnostic fabrication, iterative alteration, and definitive fabrication (figure 2).18 the shape capture portion is mainly accomplished through hand-casting -using plaster or fiberglass bandage, as well as three-dimensional scanning. modification of the captured shape is accomplished manually to a physical model or digitally using a computeraided design (cad) program and are often standardized. diagnostic fabrication includes creation and application of a clear plastic socket, commonly petg, to the patient’s residual limb to inspect fit and allow alterations.4 these alterations are made in an iterative fashion, sometimes with multiple check sockets, until a satisfactory fit is achieved. a definitive socket is then fabricated from the resultant form. definitive sockets are designed for long-term use, with fewer options for alterations compared to the diagnostic sockets. while this fabrication process is commonplace, rigid-volume sockets are inherently limited with some alterations being exceedingly difficult, time-consuming, or impossible to make through the various modification techniques and each having their associated costs. some alterations are impossible to reverse once made, requiring the socket to be remade altogether. therefore, the patient and practitioner are unavoidably presented with the decision to make the alteration or not. this results in a sub-optimal situation for both parties involved to achieve the best socket fit possible. further, third-party payers often limit the quantity and frequency at which new sockets can be reimbursed. the reimbursement for periodic replacement of sockets often constitutes a significant percentage or majority of a prosthetic clinic’s revenue stream. adjustable-volume sockets create efficiencies in the fitting process by eliminating or simplifying steps. prefabricated sockets are manufactured in mass quantities to create an economy of scale for the manufacturer. they are loosely designed around traditional socket designs and present one or several options for custom-fitting by the skilled practitioner. these options include pad kits, adjustable cables, and air bladders, while also enabling trimming and heat-molding.13 prefabricated sockets eliminate the modification step and definitive fabrication portions of the process while simplifying diagnostic fabrication and iterative alteration into configuration of macro-adjustable elements in real-time with the patient. shape capture is simplified to measurement for accurate size order. prefabricated sockets present reasonable fit options to a majority of amputees who present with standard residual limb anatomy. biomechanical control is a topic of debate with prefabricated sockets as associated transtibial (tt) designs implement pre-tibial pads to offload bony prominences and the tf designs are mostly sub-ischial in nature. modular sockets seek to create similar efficiencies in fitting by eliminating modification and simplifying diagnostic and definitive fabrication into assembly of prefabricated modules. an economy of scale can be realized in mass production of these modules similar to prefabricated sockets. modular sockets present some advantages over rigid-volume sockets regarding customization as elements can be placed in direct response to residual limb anatomy and biomechanics. many of the modules are themselves heat adjustable and can be individually customized in this way as well. diagnostic sockets are sometimes used for traditional shape capture measurements iterative adjustment real-time adjustment on patient delivery patient accepts definitive device shape capture casting, measurements assembly prefabricated parts iterative adjustment real-time adjustment of modular elements delivery patient accepts definitive device shape capture casting, measurements modification standard or reduced set diagnostic fitting check socket iterative adjustment real-time adjustments of elements definitive fabrication laminate rigid socket delivery patient accepts definitive device custom adjustable shape capture casting, measurements modification standard set diagnostic fitting check socket iterative adjustment heat-mold, cut down, pads, socks, etc. definitive fabrication laminate rigid socket delivery patient accepts definitive device modular prefabricated figure 2: socket fitting processes. https://doi.org/10.33137/cpoj.v4i2.35208 5 klenow td, schulz j. adjustable-volume prosthetic sockets: market overview and value propositions. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.17. https://doi.org/10.33137/cpoj.v4i2.35208 issn: 2561-987x adjustable-volume prosthetic sockets klenow & schulz. 2021 cpoj special s p e c ia l i s s u e offsite fabrication of these systems but are not always required. modules often include component attachment blocks, struts, panels, and some circumferential binding element. upper extremity designs can include cuffs and tf designs often implement a telescoping ischial seat module.16,19 these systems typically, but not always, include a micro-adjustable element. custom sockets with adjustable elements are varied in their fitting efficiencies. many of the benefits with these systems come in the form of the aforementioned daily microadjustability for the patient. in custom sockets with integrated adjustable features, such as the cable/panel type, more fabrication time and labor are often required at the outset. with the revofit™ and quatro™ systems, for example, the same standard fabrication techniques are required in addition to the feature installation.5 the increased socket fit range these systems present, however, may potentially reduce the number of diagnostic fitting and iterative changes required as they present additional options for customization and biomechanical control depending on application. reduced number of follow-up appointments are often marketed by the system manufacturers. custom sockets with adjustable components alter fabrication only slightly or not at all, but also present those options for adjustability in real-time with the patient.9 custom-hybrid adjustable systems with multiple macroand micro-adjustable attributes also present mixed efficiencies in fitting and follow-up.5 the socket-less™ socket systems by martin bionics simplify or eliminate several steps of the fabrication process including in shape capture, modification, and iterative alteration. initial diagnostic and definitive fabrication are slightly prolonged by the additional assembly time needed to finish the increased topographical length of socket trimlines due to the many cut-outs, drilling holes to affix the socket-less socket™ components, and converting components from diagnostic to definitive. the total number of fitting appointments is typically reduced since iterative alterations are made in real-time with the patient versus in the lab and need for additional check sockets is often reduced. customization of the socket-less socket™ includes simply moving a chicago-type thumb screw from one hole to another in the thermoplastic straps. so, significant adjustments or socket re-makes can be reduced to a matter of seconds. additionally, the adjustable nature of these sockets and options for customization throughout the product life cycle could facilitate reduced overutilization costs per beneficiary thereby reducing overall cost to thirdparty payers. shape capture and modification are simplified with the martin bionics system since large portions of the laminated socket are eliminated. the tf version, for example, eliminates the need for high-definition shape capture of the pelvic anatomy and modification of the traditional brim due to integration of the swingbrim™. one approach of the tf system includes replacement of the laminated lateral wall with metal bars to suspend the components, presenting an efficiency by limiting shape capture and modification further to the distal third of the residual limb. the iterative alteration step is simplified as the check socket no longer requires heat guns and grinders but utilizes the real-time adjustments through straps with thumb screws instead. the macro-adjustability of the systems allows for considerably more options for customization to the patient and, perhaps more profoundly, the ability to reverse a socket adjustment if it is ultimately deemed undesirable to the patient. the cj sail socket is another custom-hybrid adjustable system. this system therefore presents efficiencies through simplification of the modification and iterative alteration steps of fabrication. likewise, additional time may be required in diagnostic and definitive fabrication steps to prepare the socket and integrate the textile. since the textile piece conforms to the patient’s residual limb shape though, the need for extensive form modifications are reduced. the sub-ischial tf version also reduces the amount of shape capture detail and modification needed at the ischial seat. structural testing of the cj sail socket and martin bionics systems have not been disseminated in the literature to date, so long-term maintenance requirements are unknown compared to rigid-volume sockets which are known for durability. however, the major cause of socket replacement is from residual limb volume change and subsequent fit and discomfort issues which conforming and adjustable-volume sockets seek to resolve. conclusion the purpose of this article is to provide a market overview for the subcategory of adjustable prosthetic sockets, their reported end-user benefits, and potential fitting process efficiencies. the subcategories of pre-fabricated, modular, and custom sockets with adjustable elements are identified. the custom sockets with adjustable elements subcategory is further delineated into addition of adjustable component or adjustable features. custom-hybrid adjustable systems, which span all three major categories and have some other radically-unique design feature, are also presented. adjustable sockets present opportunities for efficiencies through innovation of the various stages of fitting including shape capture, form modification, diagnostic fabrication, iterative alteration, and definitive fabrication. long-term efficiencies are also created through reported reductions in follow-up time and overutilization. adjustable sockets in their various forms are disruptive technologies, but likely represent a lasting innovation to the field of clinical prosthetics. call to action • reimbursement reform adjustable-volume socket technologies have disrupted the traditional delivery model in clinical prosthetics and reimbursement reform is needed to ensure longevity and capitalization of the trend. since the technology shifts the emphasis in fitting from skilled labor of fabrication to clinical expertise and long-term care, corresponding https://doi.org/10.33137/cpoj.v4i2.35208 https://cjsocket.com/ 6 klenow td, schulz j. adjustable-volume prosthetic sockets: market overview and value propositions. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.17. https://doi.org/10.33137/cpoj.v4i2.35208 issn: 2561-987x adjustable-volume prosthetic sockets klenow & schulz. 2021 cpoj special s p e c ia l i s s u e reimbursement items should be introduced. in the current fee-for-device delivery model this would manifest itself in the form of additional l-codes. in a hybridized model, allowances for clinical services not associated with initial delivery of the device should be implemented including evaluation, outcome measure collection, and long-term adjustment.20 in addition, the administrative burden for repair and replacement of minor parts billing should be reduced to encourage their use. these proposed reforms should ultimately reduce cost for third-party payers and the healthcare system overall through reduced costs per beneficiary resultant from reduced overutilization. the principles of these adjustable-volume systems also incorporate well into fee-for-outcome and fee-for-value models through the presented efficiencies and prospect of improved outcomes in the long-term. these reimbursement models have permeated allied health in other areas, but not durable medical equipment yet. prosthetic services should be separated from dme in the policy of payers, as it is in the uniform glossary of health coverage and medical terms, establishing the field as its own independent specialty.21 this would allow for simplified implementation of costsaving strategies apart from fee-for-device including fee-foroutcome, bundled payments, and capitation. • prosthetist adaptations as innovation in the field of clinical prosthetics occurs and reimbursement models evolve in the current progressive healthcare climate, prosthetists must also advance care delivery systems. currently, prosthetic prescription, fitting, and delivery relies heavily on the individual experience and expertise of the clinicians. however, the experience and educational background of these professionals is quite varied, reflecting the changing collective thought of the field at various points in time. if prosthetists are to set themselves apart from durable medical equipment suppliers, their associated skillset must also set itself apart. since the patient population of prosthetic users is so unique, this skillset must include an unparalleled and self-evident expertise of the most unique aspect of the patient: the residual limb. further acceptance of advanced assessment techniques, such as digital shape capture, activity monitoring, and physical performance outcome measures, is required. in addition, the field of prosthetics should continue and more earnestly push for licensure of its practitioners throughout the united states, canada, and abroad. this will enable the true clinical independence, professional validation, and service-related reimbursement currently being sought. other allied health professionals including physical therapists, occupational therapists, podiatrists, and audiologists have accomplished similar goals correspondingly. acknowledgements none. declaration of conflicting interests tyler d. klenow is an employee of martin bionics clinical care and joel schulz is an employee for martin bionics innovations, the providers of the socket-less™ socket systems. sources of support none. references 1.collins dm, karmarkar a, relich r, pasquina pf, cooper ra. review of research on prosthetic devices for lower extremity amputation. crit rev biomed eng. 2006; 34(5):379-438. doi: 10.1615/critrevbiomedeng.v34.i5.20 2.safari mr & meier mr. systematic review of effects of current transtibial prosthetic socket designs-part 2: quantitative outcomes. j rehabil res dev. 2015;52(2):509-26. doi: 10.1682/ jrrd.2014.08.0184 3.stevens pm, depalma rr, wurdeman sr. transtibial socket design, interface, and suspension: a clinical practice guideline. j prosthet orthot. 2019; 31(3): 172-8. doi: 10.1097/jpo. 0000000000000219 4.abdulkadir a & okur sc. effects of test socket on pain, prosthesis satisfaction, and functionality in patients with transfemoral and transtibial amputations. med sci monit. 2018; 24:4031-7. doi: 10.12659/msm.910858. 5.paterno l, ibrahimi m, gruppioni e, meciassi a, ricotti l. sockets for limb prostheses: a review of existing technologies and open challenges. ieee trans biomed eng. 2018;65(9): 1996-2010. doi: 10.1109/tbme.2017.2775100 6.chatterjee s, majumder s, chowdhury ra, subrata p. review: problems with use of trans-tibial prosthesis. j med imaging health informatics. 2016;6(2):269-84. doi:10.1166/jmihi.2016.1686. 7. al-fakih ea, osman naa, adikan frm. techniques for interface stress measurements within prosthetic sockets of transtibial amputees: a review of the past 50 years of research. sensors. 2016;16:1119. doi: 10.3390/s16071119. 8.sanders je & fatone s. residual limb volume change: systematic review of measurement and management. j rehabil res dev. 2011; 48(8): 949-86. doi: 10.1682/jrrd.2010.09.0189 9.sanders je, cagle jc, harrison ds, myers tr, allyn kj. how does adding and removing liquid from socket bladders affect residual limb fluid volume? j rehabil res dev. 2013; 50(6):845-60. doi: 10.1682/jrrd.2012.06.0121 10.balk em, gazula a, markozannes g, kimmel hj, saldanha ij, resnik lj, et al. lower limb prostheses: measurement instruments, comparison of component effects by subgroups, and long-term outcomes. comparative effectiveness review: number 213. u.s. department of health and human services. 2018. doi:10.23970/ahrqepccer213 11.fortington lv, geertzen jhb, van netten jj, postema k, rommers gm, dijkstra pu. short and long term mortality rates after https://doi.org/10.33137/cpoj.v4i2.35208 7 klenow td, schulz j. adjustable-volume prosthetic sockets: market overview and value propositions. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.17. https://doi.org/10.33137/cpoj.v4i2.35208 issn: 2561-987x adjustable-volume prosthetic sockets klenow & schulz. 2021 cpoj special s p e c ia l i s s u e a lower limb amputation. eur j vas endovas surg. 2013; 46(1): 124-31. doi:10.1016/j/ejvs.2013.03.024 12.wang y, tan q, pu f, boone d, zhang m. a review of the application of additive manufacturing in prosthetic and orthotic clinics from a biomechanical prospective. j.eng. 2020; doi:10.1016/j.eng.2020.07.019 13.dillingham t, kenia j, shofer f, marschalek j. a prospective assessment of an adjustable, immediate fit, transtibial prosthesis. physical med rehabil j. 2019; 11: 1210-7. doi: 10.1002/ pmrj.12133 14.shuaili na, aslani n, duff l, mcgarry a. transtibial prosthetic socket design and suspension mechanism: a literature review. j prosthet orthot. 2019;31:224-45. doi: 10.1097/jpo. 0000000000000258 15.highsmith mj, kahle jt, miro rm, orendurff ms, lewandowski al, orriola jj, et al. prosthetic interventions for people with transtibial amputation: systematic review and meta-analysis of high-quality prospective literature and systematic reviews. j rehabil res dev. 2016; 53: 157-84. doi:10.1682/jrrd. 2015.03.0046 16.kahle jt, klenow td, highsmith mj. comparative effectiveness of an adjustable transfemoral prosthetic interface accommodating volume fluctuation: a case study. technol innov. 2016; 18(2-3): 175-83. doi: 10.21300/18.2-3.2016.175 17. kahle j, miro rm, ho lt, porter m, lura dj, carey sl, et al. the effect of the transfemoral prosthetic socket interface designs on skeletal motion and socket comfort: a randomized clinical trial. prosthet orthot int. 2020; 44(3): 145-54. doi: 10.1177/ 0309364620913459 18.shurr dg & michael jw. methods, materials, and mechanics. prosthetics and orthotics. 2nd ed. upper saddle river, nj: pearson education; 2002:21-23. 19.johnson a, lee j. designing for affordability, application, and performance: the international transradial adjustable limb prosthesis. j prosthet orthot. 2012;24(2):80-5. doi: 10.1097/jpo.0b013e3182501fd7 20.bostock f, brandt jm, greene s, smith h. reimbursement in o&p: a changing of the tide?. o&p news [internet]. 2019; [cited 2020, october 28]. available from: https://issuu.com/americanoandp/docs/opn_spring_issuu_de9bd7 5400c720. 21.glossary of health coverage and medical terms. healthcare.gov webpage [internet]. [cited 2020, october 28]. available from: https://www.healthcare.gov/sbc-glossary/. authors scientific biography tyler klenow, ms, mba, lcpo, faaop is a graduate of the master of science in orthotics & prosthetics program at eastern michigan university and the master of business administration program in the nathan m. bisk school of business at florida institute of technology. he is currently the co-chair of the clinical education planning committee for the american orthotic & prosthetic association (aopa) and has previously served as the chairman of the outcomes research committee for the american academy of orthotists and prosthetists. tyler specializes in prosthetic research including outcome measures, biomechanics, and secondary knowledge. he joined martin bionics clinical care as a program manager and clinic leader in 2020. joel schulz, ba, bspo, clp is a graduate of the prosthetics and orthotics program at the university of washington and has worked in several roles in the prosthetics industry over an 18year career. he worked on the the defense advanced research projects agency (darpa) revolutionizing prosthetics 2009 project with johns hopkins applied physics laboratory while at orthocare innovations. joel codeveloped a fabric-based exoskeletal jacket with the national aeronautics and space administration warrior web program. he has experience in computer aided design (cad), animatronics, prosthetic socket design, and has lectured for prosthetic manufacturers and training programs as well. he worked for the original martin bionics company in 2007 and joined martin bionics innovations as a design engineer and research prosthetist in 2014. https://doi.org/10.33137/cpoj.v4i2.35208 https://issuu.com/americanoandp/docs/opn_spring_issuu_de9bd75400c720 https://issuu.com/americanoandp/docs/opn_spring_issuu_de9bd75400c720 https://www.healthcare.gov/sbc-glossary/ all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.35298 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 stakeholder perspectives health economics in the field of prosthetics and orthotics: a global perspective kannenberg a1,*, seidinger s 2 1 otto bock healthcare lp, austin, texas, usa. 2 otto bock healthcare gmbh, vienna, austria. introduction with populations aging and medical progress accelerating, the financial pressure on health care systems around the world is constantly increasing. as the resources that can be spent on health care are limited, policymakers have the challenge to balance spending and health outcomes while preventing possible inequalities in beneficiary access, such as age discrimination of the elderly. health technology assessments (htas) are performed by synthesizing information and evidence on the clinical, economic, social, and ethical value of health technologies with the objective to inform safe and effective health policies, especially with respect to appropriate coverage and reasonable reimbursement. health-economic and budget-impact analyses originally started in the early 1990s and have developed into a standard tool to inform decisionmaking for pharmaceuticals. analyses have meanwhile expanded to medical devices and clinical procedures using modified methodology that better reflects their specific needs. as medical devices differ considerably from pharmaceuticals, there is still a need to refine the hta approach to these technologies.1,2 while common for medical devices used in hospitals or by physicians, health economics is still in its infancy in the field of prosthetics and orthotics (p&o). even worse, most p&o products, with notable exceptions, such as microprocessor knees, still lack a solid body of evidence for meaningful clinical benefits that would be required to determine the effectiveness side of a cost-effectiveness equation. there is a considerable amount of biomechanical research that may have even shown promising findings in the gait lab. however, many manufacturers still fall short in conducting meaningful clinical research. for example, while increased toe open access volume 4, issue 2, article no.6. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract the rapid advancement of prosthetic and orthotic (p&o) technology raises the question how the industry can ensure that patients have access to the benefits and providers get paid properly and fairly by healthcare payers. this is a challenge that not only p&o but all areas of health technology face. in many areas of medicine and health products, such as drugs and medical devices, health-technology assessments (hta) have become a standard procedure in the coverage and reimbursement process. in most countries, p&o is lagging behind that development, although some countries have already formalized hta for prosthetic and orthotic products and may even use cost-effectiveness analyses to determine pricing and payment amounts. this article gives an overview on the coverage and reimbursement processes in the united states, canada, germany, france, sweden, the united kingdom, poland, japan, and china. this selection reflects the variety and diversity of coverage and reimbursement processes that the p&o industry faces globally. the paper continues with an overview on the necessary research and investment efforts that manufacturers will have to make in the future, and contemplates the likely consequences for the manufacturer community in the market place. health economics may help support the transition from price-based to value-based coverage and reimbursement but will come at considerable costs to the industry. citation kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 keywords disability, health economics, prosthetics, orthotics, health technology assessment, manufacturer, reimbursement, research and development, willingness to pay * corresponding author andreas kannenberg, md (ger), phd executive medical director north america, otto bock healthcare lp, 11501 alterra parkway, suite 600, austin, texas, usa. e-mail: andreas.kannenberg@ottobock.com orcid id: https://orcid.org/0000-0001-7983-1744 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.35298 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.35298 mailto:andreas.kannenberg@ottobock.com https://orcid.org/0000-0001-7983-1744 2 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e clearance in the gait lab was shown for prosthetic feet with hydraulic and microprocessor-controlled ankles years ago3,4 no study has been published yet to show that these feet reduce falls in the free-living environment. having come to the conclusion that most manufacturers do not conduct robust and meaningful clinical research,5-8 let alone costeffectiveness studies, health-technology assessment bodies that have reviewed the evidence for some p&o products usually list the deficiencies in the evidence and, therefore, often abstain from compelling coverage recommendations. though there are some basic methodologic commonalities of health-economic analyses for all health technologies, a specific challenge in p&o is the relative lack of expertise in the field of disability that would be necessary to develop health-economic models that appropriately represent and reflect the specific needs and outcomes of patients. according to a recent survey, over 80% of health-economic experts said they knew far too little about this area.9 so, it is not surprising that currently no specific health-economic model exists that appropriately reflects the conditions and needs of patients with disabilities treated in p&o. that also means that manufacturers have no reliable guidance to satisfy the expectations of hta bodies. nevertheless, health-economic evaluations will very likely become an important aspect of future coverage and reimbursement decisions. therefore, the p&o industry would be welladvised to proactively approach health economics soon to be able to shape its framework rather than to wait for inadequate models to be imposed from the outside. this paper aims at giving an overview on health-economic requirements for coverage and reimbursement policies in important health care systems around the world. however, regardless of a requirement, cost-effectiveness analyses would also bring the industry in a position to argue for the value of its services and products by putting it in perspective to that of other medical services and products. for example, a health-economic study in the united states found that the incremental cost-effectiveness ratio (icer) of microprocessor-controlled prosthetic knees was comparable to that of total knee replacements but much better than that of prophylactic cardioverter defibrillator implantations.10 such findings might help influence policies even without a formal requirement for health-economic evaluations. current reimbursement system challenges for prosthetics and orthotics decision-making process for coverage currently, in the majority of health care systems worldwide, health-economic studies are not a standardized part of the decision-making process for p&o coverage, issuance of a new billing code, if applicable, or patients’ access to treatment. while public insurance infrastructure and appraisal procedures for pharmaceuticals are generally clearly regulated and medical devices are increasingly approaching these standards, coverage appraisal systems for p&o usually lag way behind and still focus primarily on clinical evidence, if any. one of the reasons is that p&o is only a tiny field in healthcare, making up less than 0.3% of the 2018 overall medicare budget in the u.s.11,12 however, the fact that individual prostheses may cost tens of thousands of dollars creates a psychological barrier with claim reviewers on the insurance side, sparking their wish to see good justification for such a big expenses. therefore, health-economic analyses may help put the cost and benefits of an advanced prosthesis or orthosis in perspective to those of other medical interventions that are considered standard of care. overview on the adoption of health economic evaluations in the field of prosthetics and orthotics in different countries for this paper, countries were selected that have a formal process to enable manufacturers to provide scientific evidence for the assessment of their products and that publish appraisal results. north america united states in 2018, u.s. health care spending totaled $3.6 trillion, amounting to 17.7% of the gross domestic product (gdp) or us$11,200 per capita — almost twice as much as many other high-income countries.13 the biggest expenditure categories are hospitals and physicians. though the amount spent on prescription drugs is growing, the proportion of health care spending for drugs is fairly stable.14 interestingly, public health care expenditures as a share of the gdp (8.3%) are comparable to other large economies. however, public health insurance in the united states (medicare, medicaid, children’s health insurance program [chip], veterans administration [va]) covers only 34 percent of the population, much less than in countries with universal coverage like canada and the united kingdom.15,16 that indicates that it costs far more to provide health care coverage in the u.s. system than anywhere else in world. despite leading the world in costs, however, the united states ranks only twenty-sixth in the world for life expectancy17 and also ranks poorly on other indicators of quality.18 thus, there would be good reason to employ health-economic evaluations to improve outcomes and manage health care costs. however, the information on the impact of health-economic analyses on the u.s. health care https://doi.org/10.33137/cpoj.v4i2.35298 3 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e system is conflicting. on one hand, the department of health and human services (hhs) in 2016 issued guidelines for regulatory impact analysis that apply to any regulatory actions that have an annual effect on the economy of us$100 million or more.19 on the other hand, medicare is prohibited by law from using cost-effectiveness in coverage determinations.20 that is reflected by the fact that the process for the development and revision of local coverage determinations (lcd) that also applies to prosthetics and orthotics does require the submission of clinical evidence on new products published in peerreviewed medical journals, but not the submission of any health-economic evaluations of the new technology.21 commercial health care insurances have more discretion with regards to health economics. however, the affordable care act, though encouraging cost-effectiveness and comparative clinical research, also restricts the use of that evidence for determining coverage and reimbursement.22 nevertheless, health-economic analyses of new interventions, drugs and medical devices are quite common in the u.s. however, medicare and commercial insurances have separate departments and processes to determine coverage and payment amounts. for coverage, they usually focus on published clinical evidence and the methodological quality of the research conducted, regardless of the price or reimbursement requested. health-economic analyses are usually not considered for coverage decisions. only after a new intervention has been found to be effective and worth covering, health-economic analyses may be used to help determine an adequate payment amount by providing the cost-effectiveness perspective that may be compared to that of other interventions already covered. due to the known challenges to meet the formal criteria of high-quality clinical research in prosthetics and orthotics, such as blinding and randomized parallel groups, manufacturers often fail to even pass the first gate of evaluation of the evidence for clinical benefits and effectiveness. however, if payers even dispute the clinical effectiveness of prosthetic and orthotic devices and deny coverage for lack of evidence thereof, there is no need to analyze cost-effectiveness to guide determination of pricing and reimbursement. that was basically confirmed by the experience that a healtheconomic evaluation of microprocessor controlled prosthetic knees (mpk) commissioned by the american orthotic and prosthetic association (aopa) and conducted by the rand corporation10 was widely ignored by healthcare payers and lawmakers. for community ambulators (k3), the study confirmed that the previous decision to cover mpk was cost-effective, whereas for limited community ambulators (k2), the results were rejected for insufficient clinical evidence as a solid basis for a cost-effectiveness analysis. given the dire evidence situation for many p&o products, “health economy” is mostly interpreted as cost containment and payment reduction by payers, be it through “least costly alternative” provisions, wide and more inclusive interpretation of billing codes (exclusion of “unbundling” of features and functions), and contracts with ever-dwindling payment rates. these challenges are a clear indication that u.s. healthcare payers have not yet understood the value of p&o care. another issue, especially for innovative manufacturers, is that payers clear coverage for billing codes rather than specific products. in most cases, coverage of a billing code is approved based on the evidence for one specific product that is usually the predicate device for that code. however, once coverage of that code is approved, followers can take advantage of it with me-too products that do not need evidence for their clinical effectiveness anymore and can, thus, be offered at a lower price. canada canada spends about 11.1% of its gdp on healthcare, comparable to the level of other high-income countries.23 the canadian healthcare system is predominantly funded publicly with only 30% of funding coming from the private sector. the federal government provides health care funding to the 13 provinces and territories through the canada health transfer and other fiscal transfers.24 provincial and territorial health authorities have the responsibility to meet the basic health service requirements of the canada health act (cha) that requires coverage of hospital services, physician services, surgical-dental services provided by hospitals, medical practitioners or dentists.25 outside the basic health services mandated by the cha, provinces and territories have the power to decide what packages of services they will provide. this provincial independence has resulted in a large variation of coverage between provinces.26-28 per capita spending in 2016 for all of canada was projected to be can$6,299, but spending by province ranged from can$5,822 in québec to a high of can$7,256 in newfoundland and labrador.23 these variations in coverage do also and specifically apply to prosthetics, ranging from no formal coverage policies and prosthetic coverage in newfoundland & labrador and prince edward island to coverage of up to can$17,690 towards select advanced components in ontario.28 health technology assessments (hta) started in canada about 25 years ago with the establishment of the conseil d´evaluation des technologies de la santé (today: agence des technologies et des modes intervention en santé [aetmis]) in quebec, soon followed by the canadian coordinating office of health technology assessment (today: canadian agency for drugs and technologies in health [cadth]) at the federal level. in addition, many of the larger provinces have their own independent bodies, such as the ontario health technology advisory committee https://doi.org/10.33137/cpoj.v4i2.35298 4 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e (ohtac). however, in the past, economic factors were not nearly as predictive of recommendations by the hta agencies as clinical reasons and clinical certainty of effect. also, the health-economic approach has usually been more simplistic, focusing on unit cost comparisons rather than true cost-effectiveness. for example, the odds of a drug being recommended were nine times higher if that drug was cheaper than a comparator drug, regardless of absolute cost-effectiveness.28 that may change with increasing financial pressure on the healthcare system in the future. however, a recent study even suggested using different thresholds for cost-effectiveness analyses for each of the 13 provinces and territories based on disability-adjusted life years (daly) averted and the actual level of health care expenditures in the respective province rather than one national threshold for canada.29 while such an approach might be considered appropriate from the perspective of provincial health authorities, it would make it much more difficult for providers and manufacturers to navigate the canadian healthcare system. to our knowledge, only the c-leg has been subjected to formal reviews of clinical evidence and cost-effectiveness by both the evidence based practice group of worksafe bc in 2003, updated in 2009,6 and cadth in 2009,7 both with favorable recommendations. however, not all provinces and territories have adopted them. similar as the situation in the united states, the most likely reason is the limited methodological quality of most of the prosthetic research that does not provide a solid basis for costeffectiveness analyses. thus, the quality of clinical research in prosthetics needs to be improved first. europe the european network for hta (eunethta) enables the european union to perform one hta for several or all european countries to reduce research efforts. both national agencies and manufacturers can initiate an evaluation. the focus of eunethta is on medical devices of classes iii and ii. however, other technologies might open the door for class i.30 the austrian hta agency has been chosen by eunethta to prioritize projects for other technologies and has already started a national assessment of exoskeletons and functional electrical stimulation in stroke rehabilitation units in austria. in general, health economic studies are only considered if published in a peerreviewed journal. the interaction between hta bodies and manufacturers is refined by the obligation of the latter to continuously document the medical benefits and safety of their medical products along their life cycle.31 however, it must be considered that eunethta’s recommendations are not legally binding for eu countries and that the implementation of this network is far from being completed. therefore, in the next section we present the diversity of the evaluation of health-economic evidence across select european countries. germany in 2018, germany spent €390.6 billion (us$460.9 billion) or €4,712 (us$5,560) per capita on health care, equaling 11.7% of the gdp.32 the statutory health insurance provides comprehensive medical coverage to 90% of the population, with premiums depending on income.33 in principle, people with disabilities are entitled to coverage of state-of-the-art prosthetic and orthotic devices in accordance with the statutory provisions of the social code (sozialgesetzbuch [sgb]; §4 and §47 sgb ix;34 §33 and §27 sgb v)35,36 as soon as the ce mark is approved in europe. in addition, the federal social court adjudicated for mpks that patients are entitled “to receive aids that compensate the disability and enable equal function for activities of daily living as an able-bodied person”.37 to be listed in the directory of medical aids (“gkv hilfsmittelverzeichnis”), the clinical benefit of a medical device must be demonstrated. under certain circumstances, research questions for the listing of new device categories may be negotiated. usually, the insurances negotiate contracts and reimbursement amounts with the federal guild of prosthetists and orthotists based on the directory. in principle, the federal joint committee (g-ba) of physicians and health insurances, the highest decision-making body for coverage in the german healthcare system, would have the authority to commission a health-economic evaluation by the hta body iqwig (institute for quality and efficiency in health care). this has been never done for prosthetics or orthotics thus far.38 if a manufacturer conducts a health-economic study in a german context, the iqwig methodology is to be followed and modeled on a german cohort.39 an example is the cost-effectiveness study and budget impact analysis for c-leg in a german context.40 the value of a healtheconomic evaluation may inform statutory health insurances and help grant extended access for sub-groups of patients which are likely perceived as cost-intensive. france the haute authorité de santé (has)41 has a published, clearly defined appraisal process including instructions for the interaction with manufacturers that is to be followed for drugs, medical devices and p&o equally. this is also noticeable in the assessment expertise of the commission nationale d`évaluation des dispositifs médicaux et des technologies de santé for prostheses and orthoses.42 in this concept, the level of evidence and clinical meaningfulness of benefits provided for a medical device by a manufacturer is systematically tied to the level of possible coverage (maximum number of patients fitted per year) and reimbursement (payment amount). an additional https://doi.org/10.33137/cpoj.v4i2.35298 5 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e requirement is that, whenever possible, french research sites should participate in a study, or the setting of a study should be transferable to the research and/or care setting in france. the benefit of the french model is that there is a cooperation between the has, clinical experts and the manufacturer in developing research projects and defining the relevant outcomes. if the study was conducted as agreed upon with the has, coverage is granted for a period of 5 years, after which it has to be renewed for another 5 years with another study that demonstrates that patients use the device in their daily lives. however, this coverage does not mean that the payment amount is fixed and secured, as discount negotiations may be initiated by the has on a yearly basis. health-economic studies can support both the initial application and reimbursement negotiation and the 5-yearly renewals. despite the benefits of being able to negotiate the study details with the has, the process is usually time-consuming and results in considerable delays in coverage compared to other european countries. in addition, the expectations of the has towards study design and outcomes are often so unique that manufacturers have to conduct specific studies that are of limited or even no value for coverage negotiations in other countries. nordic countries / sweden sweden has a long tradition of a consensus-oriented culture that also applies to the healthcare system. as soon as a p&o product is available on the market, individual patient coverage may be claimed on a case-by-case basis. however, if general public coverage is pursued, especially for high-priced innovative products, a health-technology assessment is to be initiated by a health care professional (hcp).43-45 manufacturers are not intended to do this as a clear need for the new treatment option must be requested by a hcp. this is the common approach to appraisals in 21 counties, with an evidence review being at the core of the assessment procedure. the diversity in additional assessment tools ranges from mini-htas to coverage with evidence development. the methodology required is the same for drugs, medical devices and p&o. it is comprehensible and achievable:46 • national health databases and registries47,48 must be used. • clinical experts should be consulted for modeling. • health-economic studies required in cohorts < 65 years of age from a payer´s and a social perspective. one example for this is a cost-effectiveness study for kenevo, an mpk for limited community ambulators, performed by kuhlmann et al. it found icers of sek 138,003 (€11,138 / us$13,143) per quality-adjusted life year (qaly) gained for prosthesis users 65+ years with diabetes/vascular disease and sek 114,772 (€9,263 / us$10,930) per qaly gained for those with other etiologies.49 according to the published methodology,46 3 levels of thresholds are used for appraisal: “low cost” with <sek 100,000 (about us$ 10,000), “high cost” with >sek 500,000 (about us$ 45,000) per qaly, and “very high cost” with >sek 1,000,000 (about us$ 90,000) per qaly. health-economic studies may be seen as an essential aspect to obtain a public reimbursement policy in the counties. poland currently microprocessor-controlled prosthetic technology is not covered by the public health care system. nevertheless, due to the country’s economic development and growth, its coverage is being discussed. there are two different pathways working in parallel to appraise health technologies including p&o that both take health economics into account to some extent. the pathway based on the new act on health care services financed by public resources,50 introduced in 2012, is based on a welldescribed procedure of reimbursement decision-making for specific products with publication of the findings. the other one is based on the reimbursement act of 201151 with an hta process that always evaluates an entire class of products. reimbursed products are then published in the list of medical devices dispensed to patients on professional prescription. during the hta process, a “threshold price” is calculated52,53 that ensures that the icer does not exceed three times the per-capita gdp (2019: us$ 15,595, resulting in a threshold of us$ 46,785).54 united kingdom the uk has 3 hta bodies, each of which has its own approach to the assessment of health technologies for the national health service (nhs) trusts in england,55 scotland,56 wales57 and northern ireland58 (adapt national institute for clinical excellence [nice] guidance after confirming it is applicable locally), all of them mainly driven by health-economic evidence. third-party assessments have to follow the hta bodies’ assessment methodology. the nice has adopted a cost-effectiveness threshold of £20,000 (us$27,200) per qaly,59 which is a benchmark also used within the eu if no national thresholds exist. the nhs england reviewed clinical outcomes as well as health-economic data for the clinical commissioning policy on microprocessor-controlled prosthetic knees in 2016.60 though the majority of the available evidence was generated with c-leg, the policy has granted coverage for mpks in general under the condition that patients meet certain qualifying criteria. https://doi.org/10.33137/cpoj.v4i2.35298 6 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e also in 2016, the national institute for health research commissioned an hta of the “orthotic management of instability of the knee related to neuromuscular and central nervous system disorders including economics”,8 concluded that the evidence on the effectiveness of orthoses is limited, especially with regards to outcomes that are important to orthoses users, emphasizing the need for high-quality research on the effectiveness and costeffectiveness of orthoses and the development of a core set of outcome measures. as uk hta reports are highly regarded by other european agencies and vice versa, these reports in the p&o segment in conjunction with the implementation of the medical device directive must be taken seriously by manufacturers. asia-pacific the implementation and development of health-technology assessments in the relatively new healthcare systems in asian countries has taken place with a time delay compared to the usa and europe. the growing necessity to provide the best value for the available resources while safeguarding accessibility to care has only recently led to an increasing number of asian countries (malaysia, thailand, south korea, vietnam, indonesia, japan, and china) that have started implementing htas. however, the evaluation processes for clinical and economic evidence of healthcare technologies is often not yet formalized.61 in most cases, p&o is still treated as a separate sector that is not (yet) affected. in general, the assessment of clinical outcomes is particularly complex since historically, many international pharmaceutical companies or medical device manufacturers have not conducted studies in asia. japan japan achieved universal health insurance coverage in 1961.61 healthcare spending as a share of gdp was 10.9%, the sixth highest among oecd countries, and per-capita expenses were us$ 4,519 in 2018.62 today the country is ranked highly across numerous health indicators.63 after a 3-year hta pilot testing phase, htas including health economic studies and budget-impact analyses were formally implemented in 2019.62-64 in general, a payer perspective is required in costeffectiveness studies. in case the intervention has an impact on productivity, a social perspective according to the core2health methodology64,65 is preferred. japan has a policy of tight control of health care costs64 and is the first country using an algorithmic method for icer-based pricing.66 that means that price reductions are executed in a 3-layer approach: 30% if the icer is >5 million yen (about us$ 50,000) per qaly, 60% if the icer is >7.5 million yen (about us$ 75,000) per qaly, and 90% if the icer exceeds 10 million yen (about us$ 100,000) per qaly. for rare diseases, cancer or pediatric therapies, 50% higher thresholds are acceptable. nevertheless, there is concern that this approach does not completely conform with ispor recommendations and does not use the icer exclusively to demonstrate cost-effectiveness.67 currently, p&o is not appraised for public reimbursement under this process. however, clinical outcome (effectiveness) is reviewed and published health-economic studies or public reports of hta bodies are supportive to obtain public reimbursement. coverage is subsequently determined by the 47 prefectures and 1,718 municipalities.68 individual case-by-case reimbursement review is a common approach in p&o. if a policy for reimbursement is to be established, the opinion of a medical society and guidelines are required. china in china a transformation process of the healthcare system is ongoing with the goal to achieve access of all citizens to the same healthcare standards in all provinces.69 the harmonization process for one national health-technology assessment standard is one part of it. the latest initiative was started in 2016 by the china national health development research center (cnhdrc) to develop hta capacity and expertise by founding the china health policy and technology assessment network which compromises 29 agencies, universities, hospitals and professional associations in 2016.69-71 an hta guideline development process is also ongoing to strengthen the implementation of hta, with a first publication of the china guidelines for pharmacoeconomic evaluations in 2015 and a nationwide task force to continuously develop and refine them.72 the chinese health insurance system is a patchwork of different types of mandatory and voluntary private health insurances. most chinese residents are covered by up to three types of basic social health insurance (bshi), namely, health insurance for urban employees (hiue), health insurance for urban residents (hiur), and new rural cooperative medical scheme (nrcms). this complex system has led to a diversity of multi-level payer plans.69 it has not been defined yet if health-economic studies will be used in the private health insurance sector. p&o is handled as a different sector, the role of hta is not yet defined either. health-technology assessments of certain p&o technologies have been performed in a number of countries. table 1 gives an overview on the country, the technology assessed, the level of the hta, and the institution that conducted or commissioned the hta. in total, 16 htas were identified. nine htas were conducted the payer’s side, with 8 of them being reviews of published outcomes (level 1) and one being a cea from the payer’s https://doi.org/10.33137/cpoj.v4i2.35298 7 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e perspective. two thirds of the hta assessed a single product and 33% a class of products. hta conducted by other parties included 6 analyses from a payer’s perspective, thereof only one for a product class and two from the societal perspective, both for mpks. health economic analyses may help support future coverage of true innovations health-economic analyses should primarily be performed for truly innovative products or those with high budget impact on the healthcare system to justify the efforts of the industry. this requires a well-developed research plan with scientific objectives that are relevant and beneficial to patients.81 as this is so important, it is desirable to have a transparent interaction process with payers whenever possible to obtain their perspective on what information is needed and which advancements are perceived valuable. several such evaluations may culminate in an accepted standard how to conceive a health-economic model that can guide smaller companies and payers in the future. in the research & development process, health-economic analyses of manufacturers have to deal with the challenge of little or even no availability of objective data in the table 1: overview health technology assessment activities performed. country hta level 1 outcome review hta level 2 cea payer perspective hta level 3 cea society perspective conducted by other parties a= association (industry) h= health economic institution m=manufacturer r= research group payer canada c-leg p6 canada c-leg p7 usa mp lower limb prostheses p5 usa mpk a, h10 usa genium r73 germany c-leg h, m40 france c-leg p has74 france kenevo p has75 france rheo p has81 france plié p has77 italy c-leg r, m78 italy mpk r, m79 uk mpk p60 uk orthoses neurologic knee instability p8 sweden kenevo h, m, r49 sweden osteointegration r80 total publications 8 6 2 7 9 table 2: health economic analyses in the r&d process of manufacturers and in the product life cycle.82 phase information based on hta subsequent manufacturer’s decisions early -state development • potential of a prosthesis/orthosis being cost-effective as part of manufacturer’s investment decision • prioritize between competing possibly cost-effective concepts or prostheses/ orthoses; • identify those parameters that have the largest impact on the likely cost-effectiveness of the prosthesis/orthosis in order to direct limited research funds.5 • design and management of prostheses and orthoses • regulatory and reimbursement strategy mid-state development • feasibility check of cost-effectiveness based on first observational / small clinical studies • develop optimal clinical assumptions with clinical experts • develop a disease-specific model • value proposition • health-economic study for payer review late-state development • cost-effectiveness can be demonstrated • affordability is shown with a budget-impact analysis • claims for reimbursement product life cycle • re-calculate the health economic model with extended data • validate assumptions • use to maintain or extend coverage https://doi.org/10.33137/cpoj.v4i2.35298 8 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e beginning and the need for several iterations and refinements with improving availability of data along the way. therefore, the methodological approaches can be divided in four phases (table 2). further details and limitations (table 3) have already been published by the authors elsewhere.82 willingness to pay and shift to value-based health-care funding an obvious important limitation of health-economic analyses is the ultimate determination of the “willingness to pay” of health-care payers (key figures for willingness to pay see table 4). in addition, the willingness to pay varies between countries and sometimes even between different authorities or insurances within one country.26-29 nevertheless, it is an important step towards meaningful healthcare research and a fact-based negotiation with payers. however, in times of restricted budgets, even wellperformed health-economic studies do not automatically guarantee coverage and reimbursement of a product. for priority setting in health policies, a second aspect, affordability from a payer´s perspective, must be reflected.83 this raises the challenge to the researching manufacturer to model the budget impact on resources consumed using national cohort data. if available, the effort to analyze the tremendous volume of data (drg / icd-10) is very timeconsuming. so far, two publications for mpks fulfill this concept in a german and swedish context.40,49 however, despite demonstrating the affordability of an intervention, the decision to grant coverage and reimbursement is left to the payer. shifting from a price-based to a value-based discussion may help promote this change and overcome the current barriers of capped reimbursement that attempt to force innovative technologies into existing billing schemes for established components, leaving little or even no room for the appropriate reimbursement of truly innovative components with proven clinical benefits. this will become increasingly important as patients are fitted in greater numbers with microprocessor-controlled components. in addition, hta bodies and payers should not only demand high-quality research from manufacturers of innovative devices but also value it by setting the same bar for technology followers, rather than letting them get away with just claiming equivalence to predicate devices. table 4: willingness to pay assessment key figures. cost-effectiveness budget impact defined threshold 46,53,55,59,61 absolute costs and savings83 country’s per-capita gross domestic product (gdp)84 icer accepted for payment as reference us dialysis usd 50,00085 finally, because health-economic modeling and analyses are currently uncommon in r&d processes, prosthetic manufacturers are advised to benefit from the experience of pharmaceutical and implantable medical device companies and health economic research institutions to shorten the learning curve and minimize waste of investments. likely consequences of the adoption of health-economic evaluations on the markets for prosthetic and orthotics the adoption of health-economic evaluations in p&o would require a substantial expansion of clinical research capabilities, staff and funding among manufacturers. given the current structure of the prosthetic manufacturer community with its many smaller businesses, this will present a substantial challenge. it may result in a further partition of the manufacturer community, the need to collaborate and cooperate, and perhaps even mergers. smaller companies that are unable to absorb the additional table 3: limitations to health-economic modeling and analyses in the development process and product life cycle. limitation stage implementati on • level of health economic expertise • resources (cost, time) • interdisciplinary cooperation (all relevant stakeholders) development process intervention • innovation in medical devices is often a process of continuous incremental improvement. • short life cycle compared to drugs any stage comparator • treatment standards are very often not established any stage model inputs • manufacturer’s access to national databases (cost, epidemiology) • resilient outcome measures product life cycle decision • based on analyses that contain the best knowledge available at the time. any stage optimum price setting • interaction of all stakeholders • patient potential (revenue) • estimated cost-effectiveness in daily practice early stage investment • estimates per one health-economic study published by a manufacturer range from €50,000 to €100,000 (us$60,000 to us$120,000), depending on external and internal expert involvement and model input data processing product life cycle https://doi.org/10.33137/cpoj.v4i2.35298 9 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e investments will likely have to focus on me-too products that fit into the limitations and restrictions of the current reimbursement systems. however, even the group of bigger manufacturers will likely have to make some tough decisions. clinical and health economic research is expensive and can therefore only be done for new high-price innovative products. thus, manufacturers will have to decide which of their products and r&d projects they want to support with this additional investment, leaving some of their products or even entire product categories vulnerable. another challenge that may arise is that some products may deliver their biggest benefits with a good incremental costeffectiveness ratio to a relatively small group of patients that may not be big enough to justify the r&d and research expenses. the phenomenon of disappearing innovation in small markets is well known from the pharmaceutical industry. to prevent that from happening, there are proposals to develop tests to identify likely responders and reimburse the treatment of these patients at higher rates to justify the r&d expenses and keep these small markets economically attractive.86 in p&o, the procedure of trial fittings could serve that purpose. another challenge to innovative manufacturers is the burden to beat the path for new technologies. followers wait until a favorable reimbursement infrastructure has been established, and then launch me-too products that do not require the same level of evidence as the predicate device, if any. as these manufacturers save the substantial expenses for clinical and health-economic research, they are usually able to offer their devices at lower prices. this creates a competitive advantage for me-too manufacturers in many markets and makes it more difficult for innovative companies to recoup their r&d investments. therefore, increasing requirements for demonstrating clinically meaningful patient outcomes and health-economic evidence may be perceived as a short-term advantage but long-term disadvantage for manufacturers that are willing to make the necessary research investments. however, a positive development can meanwhile be observed in the european union that now regulates product entrance in the market by requiring clinical data generated for every individual product and continuous post-marketing patient safety monitoring. this precludes the manufacturers of metoo devices from simply claiming equivalence with predicate devices. a similar model would be desirable for the us and canada to maintain the fiscal incentives of researchsupported innovation. this would be in the best interest of patients, suppliers, providers, and health care payers, as the vast majority of prosthetic and orthotic devices are currently not strictly regulated by research requirements for safety and effectiveness set by regulatory bodies. call to action manufacturers of prosthetic and orthotic products need to recognize the increasing prevalence and importance of htas for medical device coverage and reimbursement. the requirements to the evidence to be demonstrated are currently only beginning to surface. unlike the past, when most manufacturers waited for an industry leader to come forward and do the work for their product and then claimed, without any proof, that these studies also applied to their products, all manufacturers are called upon to contribute to the body of evidence for certain product categories, such as mpk or microprocessor-controlled feet. that would both substantially enlarge the body of evidence for the respective product category and fix the current limitation that study results for one product are assumed to apply to the entire category without any proof. evidence that is more representative of the product diversity in the market would certainly be much more compelling to payers. in that context, industry and professional associations are called upon to support this process of evidence generation by commissioning independently conducted systematic reviews of the existing literature. finally, health insurances and payers for o&p products in general are called upon to no longer reduce health economy in this field to simple cost savings but apply value-based approaches that are similar to those already used for other medical devices but reflect the peculiarities of o&p. ultimately, considerable transparency between payers and their willingness-to-pay thresholds for valued clinical benefits will enhance the willingness of manufactures to pursue continued innovation with a sustainable cost model. as the emphasis on demonstrated clinical effectiveness and value increases, policy makers are advised to hold individual components to comparable standards of demonstrated performance to ensure that the costs of development in this value-based model are born equally across all component developers and manufacturers. nevertheless, health economy is unable to answer the question how the inevitably incremental cost to pay for innovative, yet cost-effective services and products shall be funded. societies will need to have an open discussion to find a compromise between stimulation of medical innovation and affordability of the healthcare systems. acknowledgements none. declaration of conflicting interests both authors are full-time employees of otto bock healthcare. sources of support ottobock allowed both authors to work on this article during their regular working hours and use the company’s office equipment (computers, internet access, etc.). https://doi.org/10.33137/cpoj.v4i2.35298 10 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e references 1.orania c, wilcher b, van giessen a, taylor rs. 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https://www.globalhealthpr.com/serivices/northern-ireland/ https://www.england.nhs.uk/wp-content/uploads/2016/12/clin-comm-pol-16061p.pdf https://www.england.nhs.uk/wp-content/uploads/2016/12/clin-comm-pol-16061p.pdf https://www.oecd.org/japan/health-at-a-glance-2017-key-findings-japan-in-english.pdf https://www.oecd.org/japan/health-at-a-glance-2017-key-findings-japan-in-english.pdf https://doi.org/10.1017/s0266462319000060 https://c2h.niph.go.jp/tools/guideline/guideline_en.pdf https://apps.who.int/iris/handle/10665/259941 https://globalforum.diaglobal.org/issue/may-2%20018/coming-rapidly-of-age-health-technology-assessment-in-china/ https://globalforum.diaglobal.org/issue/may-2%20018/coming-rapidly-of-age-health-technology-assessment-in-china/ https://globalforum.diaglobal.org/issue/may-2%20018/coming-rapidly-of-age-health-technology-assessment-in-china/ https://www.has-sante.fr/upload/docs/evamed/cepp-4969_3c100%20c-leg%20_01_decembre_2015_(4969)_avis.pdf https://www.has-sante.fr/upload/docs/evamed/cepp-4969_3c100%20c-leg%20_01_decembre_2015_(4969)_avis.pdf https://www.has-sante.fr/upload/docs/evamed/cepp-4969_3c100%20c-leg%20_01_decembre_2015_(4969)_avis.pdf https://www.has-sante.fr/upload/docs/evamed/cepp-5106_kenevo_20%20septembre_2016_(5106)_avis.pdf https://www.has-sante.fr/upload/docs/evamed/cepp-5106_kenevo_20%20septembre_2016_(5106)_avis.pdf 13 kannenberg a, seidinger s. health economics in the field of prosthetics and orthotics: a global perspective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.6. https://doi.org/10.33137/cpoj.v4i2.35298 issn: 2561-987x health economics in the field of prosthetics and orthotics kannenberg & seidinger, 2021 cpoj special s p e c ia l i s s u e 76.commission nationale d’evaluation des dispositifs medicaux et des technologies de sante [national commission for the evaluation of medical devices and health technologies]. haute autorite de sante, 2018, [cited 2021 july 20]. available from: https://webzine.has-sante.fr/upload/docs/evamed/cepp5167_rheo%20knee_11_septembre_2018_(5167)_avis.pdf 77.transcription des debats [transcript of the debates]. haute autorite de sante, 2017, [cited 2021 july 20]. available from: https://www.has-sante.fr/upload/docs/application/pdf/201801/plie3_transcription_du_27_juin_2017_pc.pdf 78.cutti ag, lettieri e, del maestro m, radaelli g, luchetti m, verni g, et al. stratified cost-utility analysis of c-leg versus mechanical knees: findings from an italian sample of transfemoral amputees. prosthet orthot int. 2017; 41(3): 227-236. doi: 10.1177/0309364616637955 79.gerzeli s, torbica a, fattore g. cost utility analysis of knee prosthesis with complete microprocessor control (c-leg) compared with mechanical technology in trans-femoral amputees. eur j health econ. 2009; 10(1):47-55. doi: 10.1007/s10198-008-0102-9 80.hansson e, hagberg k, cawson m, brodtkorb patients with unilateral transfemoral amputation treated with a percutaneous osseointegrated prosthesis: a cost-effectiveness analysis. bone joint j. 2018;100-b:527–34. doi: 10.1302/0301-620x.100b4.bjj2017-0968.r1 81.clarke l, dillon mp and shiell a. a systematic review of health economic evaluations in orthotics and prosthetics: part 1– prosthetics. prosthet orthot int. 2020 doi:10.1177/ 0309364620935310 82.kannenberg a, seidinger s. health economics: the perspective of a prosthetic manufacturer. official findings of the state-of-thescience conference #13. proceedings of the american academy of orthotists & prosthetists (aaop), 2019, number 13, p49-p54. 83.bilinski a, neumann p, cohen j, thorat t, mcdaniel k, salomon ja. when cost-effective interventions are unaffordable: integrating cost-effectiveness and budget impact in priority setting for global health programs. plos med. 2017; 14(10): e1002397. doi:10.1371/journal.pmed.1002397 84.bertram m, lauer ja, de joncheere k, edeier t, hutubessy r, kieny mp et al. cost-effectiveness thresholds. bull world health organ. 2016; 94(12): 925–930. doi:10.2471/blt.15.164418 85.marseille e, larson b, kazi ds, kahn jg, rosen s. thresholds for the cost-effectiveness of interventions: alternative approaches. bull world health organ. 2015;93(2):118-24. doi: 10.2471/blt. 14.138206. 86.garrison lp, towse a. value-based pricing and reimbursement in personalised healthcare: introduction to basic health economics. j pers med. 2017;7,10; doi:10.3390/jpm7030010 authors scientific biography andreas kannenberg graduated from charité medical school at humboldt university in berlin, where he also wrote his dissertation in exercise physiology. he had worked as a physician in germany for more than 10 years before joining ottobock in 2003. he has been serving as the executive medical director north america since 2013. he coordinates ottobock’s clinical research in the americas and is part of its global medical and research team. in his prosthetic and orthotic research, he has been focusing on microprocessorcontrolled prosthetic knees, microprocessor stance and swing control orthoses, and multi-articulating hands. a recent new focus of his research has been the impact of prosthetic components on musculoskeletal pain in individuals with lower-limb amputations. he is an affiliate member of the american academy of orthotists and prosthetists (aaop) and a member of the clinical education committee of the american orthotic and prosthetic association (aopa). susanne seidinger graduated as a doctor of veterinary medicine from the veterinary university of vienna, austria, and has gained significant experience in medical affairs, health economy, healthcare policies, market access and reimbursement roles in the medical device and pharmaceutical industry. in addition, she acquired a certification in health technology assessment from sheffield university. she joined ottobock in 2017 and has been serving as director global market access management since 2019. the focus of her research has been the entire spectrum of health economic studies in highly innovative medical, prosthetic and orthotic products. https://doi.org/10.33137/cpoj.v4i2.35298 https://webzine.has-sante.fr/upload/docs/evamed/cepp-5167_rheo%20knee_11_septembre_2018_(5167)_avis.pdf https://webzine.has-sante.fr/upload/docs/evamed/cepp-5167_rheo%20knee_11_septembre_2018_(5167)_avis.pdf https://www.has-sante.fr/upload/docs/application/pdf/2018-01/plie3_transcription_du_27_juin_2017_pc.pdf https://www.has-sante.fr/upload/docs/application/pdf/2018-01/plie3_transcription_du_27_juin_2017_pc.pdf all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives ratto m. designing a digital toolchain for prosthetics: a retrospective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.16. https://doi.org/10.33137/cpoj.v4i2.36188 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.36188 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 ratto m. designing a digital toolchain for prosthetics: a retrospective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.16. https://doi.org/10.33137/cpoj.v4i2.36188 stakeholder perspectives designing a digital toolchain for prosthetics: a retrospective ratto m.* faculty of information, university of toronto, toronto, canada. introduction from 2014 until 2020, i participated in the development of a novel cad/cam system for lower-limb prosthetics sockets. that project, initiated by cbm canada, a charitable organization that supports hospitals in the developing world, and funded by corporate, non-profit, and governmental sources, was successful insofar as it developed multiple software and hardware solutions, deployed these into multiple clinical settings in different countries, and had a direct impact on the quantity and quality of prosthetic interventions in those clinics. a non-profit organization, nia technologies, was founded to support this ongoing work, and has been continually funded through philanthropic donations and corporate and nonprofit grants since 2015. the specifics of that work have previously been published1-3 and interested readers can refer to those publications for details regarding clinical outcomes, trial data, and for more information about our specific hardware and software solutions. this paper provides an overview of the work from a broader perspective, highlighting how the health economic framework, that is key to this special issue, well describes the design choices we made to attend to the multiple levels of concerns and stakeholders in the health economic framework. project overview founded in 2015, nia technology is a non-profit organization that has developed and deployed a digital scanning, design and fabrication system for the production of trans-tibial prosthetic sockets and simple orthotic devices. designed to be used in lower and middle income countries (lmic) orthopaedic clinics, the system has been built to integrate with the current international committee of the red cross (icrc) polypropylene prosthetic and orthotic (p&o) system and thus concentrates only on the socket component. this system primarily makes use of a single laptop computer, modified commodity 3d scanners and printers, and custom 3d scanning and design software called niascan and niafit respectively. the resulting system, including all software and hardware costs under us$10,000, with paediatric and adult 3d printed prosthetic sockets material costs of less than $10 per unit. the system was designed to be used in lmic contexts by orthopaedic technicians and prosthetists trained within the icrc training programs. it has been tested and deployed in four clinics: the comprehensive rehabilitation services for people with disability in uganda (corsu), the comprehensive community based rehabilitation clinic in tanzania (ccbrt), the tanzania training centre for orthopaedic technologists (tatcot) and the cambodia school of open access volume 4, issue 2, article no.16. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract from 2014 until 2020, i participated in the development of a novel cad/cam system for lower-limb prosthetic sockets for use in lower and middle income countries (lmic) orthopaedic clinical settings. this article provides an overview of the value principles that guided that work and the ways in which we attempted to support the clinical needs of our prosthetists and others in the clinical contexts. it will highlight how the health economic framework that is key to this special issue well describes the design choices we made in order to attend to the multiple levels of concerns and stakeholders we identified as key to success. citation ratto m. designing a digital toolchain for prosthetics: a retrospective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.16. https://doi.org/10.33137/cpoj.v4i2.36188 keywords health economic framework, 3d printing, innovation, lmic, values, prosthetics, orthotics, rehabilitation * corresponding author matt ratto, phd faculty of information, university of toronto, canada. e-mail: matt.ratto@utoronto.ca orcid id: https://orcid.org/0000-0002-3554-4513 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.36188 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.36188 mailto:matt.ratto@utoronto.ca https://orcid.org/0000-0002-3554-4513 2 ratto m. designing a digital toolchain for prosthetics: a retrospective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.16. https://doi.org/10.33137/cpoj.v4i2.36188 issn: 2561-987x designing a digital toolchain for prosthetics ratto m., 2021 cpoj special s p e c ia l i s s u e prosthetics and orthotics (cspo). for each site, nia technologies personnel traveled to the clinical site for one week, installing or updating equipment and carrying out three days of training with the technicians and clinicians on site. following this, nia technologies provides digital support via email and teleconference. as of february 2021, the system remains in use at corsu, ccbrt and tatcot. nia technologies has iteratively developed a design values framework which has guided our work. briefly, this framework is as follows: • design with local needs in mind as described by stakeholders in local clinical setting. • develop collaboratively and field-test/evaluate in target clinical settings. • encourage adoption and adaptation of technologies and workflow by orthopaedic technicians and clinicians in target setting. • manage and maintain locally (with ongoing technical support from nia) • focus on benefits to local stakeholders including people with disabilities, clinicians, and hospital administrators. our work has been shaped by these design values some of which were first proposed based on initial research work on p&o and in consultation with experts during workshops organized early in the project4 and iterated as our project progressed. as this framework demonstrates, an important aspect of our work has been to emphasize local agency and ownership of the p&o process and resulting technological intervention, even when doing so increased the technological complexity of the system. for example, early on in our design process we rejected the idea of a system where the operating of the design software was outsourced to an external cad specialist. instead, we focused on creating design software made to emphasize and support the knowledge of the p&o professional. while we recognized the added complexity in training and in software design this decision entailed, abiding by our design principles made such a decision necessary. our overall goal of increasing the capacities of the lmic orthopaedic clinics therefore included not just making the process of prosthetic production more efficient, but adjacent goals that relate to the overall context of p&o work in these settings. health economic framing our values framework connects loosely to the health economic framing (hef) described in this special issue. the hef emphasizes the need to consider the patients, prosthetist/orthotist, and payers as important stakeholders and the relevant contexts of prosthetic use, the clinical practices in which devices are made and patients engage in rehabilitation and training, and the institutions that provide the organization and funding (table 1). our design principles encouraged us to attend to these aspects of p&o in our design process. creating a successful p&o intervention requires attending to the multiple relationships and needs this entails. given that our primary users were p&o professionals working in lmic contexts, our design principles put the orthopaedic technician and prosthetist/orthotist at the center (figure 1). table 1: stakeholders and contexts in health economic framing. stakeholders contexts patients uses of devices prosthetists clinical and rehabilitation practices payers health care institutions this paper provides three specific ways our work incorporated our values framework and the key relationships highlighted above. example: relations to local community capacities the aim of nia’s work was to speed up the process of producing and fitting a prosthetic or orthotic device within a lmic clinical context. we designed our system to mirror and connect to the icrc polypropylene process (first developed by the icrc in 1979) for producing custom prosthetics and orthotics in order to make the most use of professional knowledge and skills already held by the clinicians. our focus was on enhancing their capacity as opposed to developing a parallel process that might bypass existing professionals. training on and access to 3d printing technology increases existing clinical capacity by providing the means for prosthetists/orthotists to make prosthetics and orthotic devices more quickly. it does not prosthetist patient other clinicians p&o colleagues payers and administrators local community orthopaedic workshop health care institution profession figure 1: centering of prosthetist in hef https://doi.org/10.33137/cpoj.v4i2.36188 3 ratto m. designing a digital toolchain for prosthetics: a retrospective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.16. https://doi.org/10.33137/cpoj.v4i2.36188 issn: 2561-987x designing a digital toolchain for prosthetics ratto m., 2021 cpoj special s p e c ia l i s s u e reduce or remove the need for clinicians in a clinical or rehabilitation setting. by building on clinical skills and expertise, the technologies we developed enabled clinicians to minimise time spent on manual production and maximise time on decisions about device design, fit, and patient care. rather than offload this work to external western partners, the 3d technology becomes another tool in the orthopaedic workshop. as an example, the team decided on using a 3d printer that is relatively easy to maintain and repair in situ, as opposed to the easiest to use printer available. this decision required the team to trust the technical capacity of the orthopaedic clinicians (as professionals already working with a range of tools and equipment), but significantly enhanced the durability of the innovation. finally, rather than try to produce all parts of the prosthetic device, our system only replaces the custom parts; the mass-produced parts – such as connectors, pylons and feet – are cheaper if sourced through icrc rather than 3d printed. we applied our design values by working within the preexisting social, professional and technical context by building on existing efforts, systems and local capacities. this stands in opposition to many other 3d printing prosthetic innovation projects that are more motivated by the application, or scaling, of a purely technological solution without the due consideration of the context that would make it viable. the former motivation offers a greater chance of implementing a long-term solution to a problem; the latter motivation can result in interventions that are not possible to sustain without the physical presence of outside short-term ‘technical experts’ (who may displace the building of more permanent capacity). example: relations to other clinicians one realization we had was a need to help our lmic prosthetist/orthotist users represent themselves as expert to other professional groups. while highly valued for the patient results prosthetists generated in their clinical settings, ethnographic work carried out with the prosthetists/orthotists and technicians revealed a systematic lack of understanding on the expert nature of their work by others.5 some of our prosthetist respondents highlighted the materiality of their work as part of the reason for this; other clinician personnel saw them mostly as ‘makers’ since they were often covered in plaster and working with the heavy vacuum pumps, grinders, and manual tools present in their workshops. the prosthetists we interviewed highlighted the ways in which the move to digital systems worked to recharacterize them as more ‘expert.’ in order to support this more fully, we encouraged the set up and design of special workstation areas, connected to but discrete from the p&o clinical setting in order to reinforce the digital aspects of their practice. our respondents found that these settings, when witnessed by other clinical care-givers helped support the similarity of their care-giving practice to other experts in the hospital. here, our design work again extended beyond the specific digital scanning, design, and printing tasks to incorporate the prosthetists’/orthotists’ relations to others in the clinical setting. equally, our design work was not just about the software and hardware that we produced, but also included the settings in which it operated. again, successful adoption of our system was supported by our understanding the full work flow and the complex health frameworks in which this p&o work was situated. example: relations to funders and payers finally, a key aspect of the development work was in generating an innovation which helped support the overall work of the clinic and the funders who provided the resources necessary for its operation. in the lmic contexts in which we deployed our solution, this is often non-profit and charitable organizations. for all new innovations, it is important to build up an evidence base to ‘prove’ the efficacy of the innovation, especially since it integrated technology which is new and relatively unfamiliar to the sector. therefore, a key aspect of our work has been continual clinical evaluation of our solutions, ultimately resulting in testing over 200 patients at four clinical sites in three different countries. the goal of these trials was to be able to make statistically significant claims about the 3d printed device with regards to durability, fit, accuracy and overall use when directly compared to traditional devices. nia set this goal for multiple reasons including both functional and symbolic needs. functionally, we needed to more fully evaluate and improve our processes in order to validate the (at the time) novel use of 3d printing in lower-limb prosthetics. symbolically, our continued investment and engagement in collaborative trials with the hospitals demonstrated nia’s commitment to improving the clinical process to the clinicians and other stakeholders, thereby strengthening key relationships. in particular, funders of clinical p&o work required clinical evidence in order to continue to support this work. we also found that the trials served to draw new funding into the orthopaedic clinic, supporting attention and interest in an area of work that required additional investment. as in the above cases, we took the need to link p&o work to funders and payers into consideration as we developed and deployed our software and hardware interventions. in particular, we worked directly with the lmic hospitals to develop forms of survey and reporting which served to provide clinical oversight and evaluation of the capacities and problems with our solutions, but also resulted in two additional forms of evidence. first, and most importantly, we generated economic evidence that used very situated material, labour, and support costs to define the potential economic benefits of our system. these typically required deep dives into the specifics of the lmic clinics, including working with the clinical staff to access actual numbers associated with orthopaedic clinical work. this often required putting relatively complex economic stories together, where the economics of the clinic including device https://doi.org/10.33137/cpoj.v4i2.36188 4 ratto m. designing a digital toolchain for prosthetics: a retrospective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.16. https://doi.org/10.33137/cpoj.v4i2.36188 issn: 2561-987x designing a digital toolchain for prosthetics ratto m., 2021 cpoj special s p e c ia l i s s u e production, rehabilitation, and education costs were connected to more general expenses associated with housing and transportation of prosthetic patients and their families during treatment. these stories assisted the hospitals in funding the use of our systems, but also often resulted in new forms of funding for the orthopaedic clinic and in some cases the hospital itself. discussion the above story and examples may make it seem that the processes through which nia technologies developed and deployed a new 3d scanning, design, and printing solution were straight-forward and clear, and the results guaranteed. nothing could be further from the truth. the work did not follow a straight-forward path, nor has acceptance of our solutions been complete. while our solution does continue to be utilized in some of the clinical settings i mentioned, in at least one of them, it was not adopted despite concerted efforts. however, the lack of adoption of nia’s solutions and, of 3d printing in p&o more generally, should not be understood as simply an issue in the capacity of 3d printing and digital systems to meet the needs of p&o. nor should this slowness be understood as the result of recalcitrant p&o professionals unwilling to adopt novel tools. while it is true that convincing orthopaedic clinicians of the merits and potential of 3d technologies has required a longer evidentiary process than we initially assumed, adoption or its lack is better understood as ‘lack of fit’ into the full framework of p&o work a key aspect that is often undervalued in contexts of emerging technologies like 3d printing and cad is the provision of training and support that must attend actual implementation. we found that both inperson and distributed forms of support were key to successful adoption, including periodic connections to other institutional actors outside the direct orthopaedic context, such as hospital administrators. developing innovations in this space requires attending to the full socio-technical context of p&o work, including the various relationships well described in the health economic framework which is the focus of this special issue. key to overcoming this challenge was helping the profession understand that 3d printing technologies would not replace clinicians with cad designers in canada (or elsewhere), nor would their craft and expertise be transformed into manual labour with the remainder being done automatically by a computer or by a different set of professional cad designers. retaining the clinician at the centre of the design and production process by integrating 3d technologies into the profession remains a major aspect of nia’s work. in doing so, our goal is to strengthen the profession and assist p&o professionals in better communicating the complexity of their care-giving work to others within their clinical contexts. to be clear, the need and clinical importance of strengthening and clarifying the role of the prosthetist was not initially apparent to us. instead, the surfacing of these aspects occurred through our sustained connection to clinical contexts and the qualitative data-gathering and analysis we carried out as part of an ethnographic process. finally, investment in professional development, quality and patient care takes time and significant resources. technology funders in particular have grown accustomed to a specific notion of scale, i.e. that technology innovations can be scaled quickly, leading to quick and large scale results, providing opportunities for funders that require a relatively short-term commitment. innovation within p&o as in any health care context requires more than just material and technical development, it also requires analysis of the deep web of relations through which the profession provides its care. conclusion media coverage of prosthetics and 3d printing has often focused on the impacts and value to the patient, while ignoring the prosthetic profession and clinical contexts of this work. personally, i continue to receive requests for ‘legs’ from people all over the world, including many requests from prosthetic wearers here in canada who, typically for economic reasons, have difficulty securing devices for their use. such requests, although wellmeaning, misconstrue the role of new technical innovations like 3d printing in the established field of prosthetics and the socio-technical contexts that guarantee clinically valid results for prosthetic users. too often, engineers and innovators from outside the field of p&o help reinforce this mistake, building systems intended to ‘transform the field’ but which typically fall flat. this paper describes an alternative innovation approach, that the team that participated in the nia technologies project ‘backed into’ as we became more knowledgeable about p&o. the values principles we developed and the hef relations to which we attended account for our relative successes; our inability in some cases to fully support the complexities of local relations equally accounts for a lack of adoption. the goal of this brief article has been to anecdotally describe the ways in which we attempted to incorporate a more complex understanding of p&o contexts as part of our project in the hopes that these experiences will provide support for others seeking to innovate. call to action many technically sophisticated tools exist that can benefit the p&o community. when adoption is slow, prosthetists and clinics are often blamed, with innovators claiming that the issue is primarily the conservative nature of the p&o discipline. our experiences developing nia technologies’ digital toolchain for lower-limb prosthetic sockets highlights the ability of p&o clinics and clinicians to be early adopters of new technologies if and when the solutions being developed address the many needs and stakeholders that exist in the field. i encourage all innovators in p&o to first, incorporate a deep dive into specific p&o contexts (public health, private providers, lmic clinics, developed world contexts, etc.) prior to developing their initial solution requirements, and second, to plan to work directly and iteratively with clinicians in their planned context of deployment. in doing so, p&o innovators will be able to https://doi.org/10.33137/cpoj.v4i2.36188 5 ratto m. designing a digital toolchain for prosthetics: a retrospective. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.16. https://doi.org/10.33137/cpoj.v4i2.36188 issn: 2561-987x designing a digital toolchain for prosthetics ratto m., 2021 cpoj special s p e c ia l i s s u e better address the complexity of the p&o context, including the stakeholders identified within the health economic framework. acknowledgements i would like to acknowledge the essential and important input provided during the course of the nia project by the many prosthetists, orthopaedic technicians, support staff, and administrators at corsu, ccbrt, tatcot, and the cambodian school of prosthetics and orthotics (cspo). i would also like to personally thank ed epp, president of helping hands, intl. for their ongoing commitment and support to nia technologies and to the overall health and wellbeing of children in the developing world. finally, i’d like to emphasize the shared and committed work of the nia team, first and foremost ceo jerry evans, and also head of programs, joshua qua hiansen, lead developer howie safeer, designer kaveh nia, and the many volunteers who have participated. declaration of conflicting interests during the time that my research on prosthetics and digital systems was being carried out, i was paid a consultancy fee by nia. at the time of writing this paper, i was no longer receive any financial fees or incentives from nia. sources of support i have been chief science officer of nia technologies, the nonprofit organization described in this article since 2015. this role has involved consultancy payment. the writing of work was not directly supported by nia, nor any of the grants nia uses for current or past support. references 1.ratto m, qua hiansen j, kaweesa m, taremwa j, heang t, kheng s, et al. an international multi-center clinical study: gauging patient experience with digitally designing, 3d trans-tibial prosthetic devices compared to manually produced prosthetic devices. international society for prosthetics and orthotics world congress (ispo), 2017, capetown, sa, may 8-11, 2017. 2.schmidt r, coons g, chen v, gmeiner t, ratto m. 3d-printed prosthetics for the developing world. insiggraph 2015: studio 2015. doi:10.1145/2785585.2792535 3.ratto m, qua hiansen j, marshall j, kaweesa m, taremwa j, heang t, et al. an international, multicenter field trial comparison between 3d-printed and icrc-manufactured transtibial prosthetic devices in low-income countries. j prosthet orthot. 2021;33(1): 54–69. doi:10.1097/jpo.0000000000000349 4.record, m. ratto, a. ratelle, a. ieraci and n. czegledy, "diy prosthetics workshops: ‘critical making’ for public understanding of human augmentation," 2013 ieee international symposium on technology and society (istas): social implications of wearable computing and augmediated reality in everyday life, 2013, 117125, doi: 10.1109/istas.2013.6613110 5.southwick d. expertise in the age of digital fabrication [doctoral thesis]. university of toronto. 2019; available from: https://tspace.library.utoronto.ca/handle/1807/95985 author scientific biography matt ratto is an associate professor in the faculty of information at the university of toronto and the bell university labs chair in humancomputer interaction. his current work explores the co-design and adoption of new digital technologies in health care. he coined the term ‘critical making” in 2007 to describe work that combines humanities insights and engineering practices and has published extensively on this concept. a current project involves the development of a costeffective software and hardware toolchain for the scanning, design, and 3d printing of lower-limb prostheses for use in the developing world. this work is being carried out in partnership with hope and healing international, and rehabilitation hospitals in canada, uganda, and tanzania. https://doi.org/10.33137/cpoj.v4i2.36188 https://tspace.library.utoronto.ca/handle/1807/95985 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 2 2020 research article blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v3i2.34481 1 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 research article investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running blakeley n.1*, silver-thorn b.1, cross j.a.2 1 department of biomedical engineering, marquette university, milwaukee, usa. 2 department of orthopaedic surgery, medical college of wisconsin, milwaukee, usa. introduction when using a running specific prosthesis (rsp) at fixed speeds on a treadmill, individuals with a transfemoral amputation (tfa) consume 45-78% more oxygen than agematched able-bodied runners.1 some individuals with tfa run in a prosthesis with an unlocked prosthetic knee, others choose to run without a prosthetic knee; their prosthetic socket and foot are linked via a non-articulating pylon (noknee condition).2,3 this non-articulating prosthesis will not buckle and collapse, regardless of load or runner fatigue, minimizing fall risk.3 consequently, distance runners with tfa have reported decreased cognitive effort for the noknee condition.3 the lack of a knee joint, however, requires that the individuals with tfa circumduct their prosthetic limb to clear the ground during swing phase.4 leg circumduction during swing shifts the center of gravity laterally, thus decreasing energy efficiency.5 open access volume 3, issue 2, article no.3. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: a number of individuals with unilateral transfemoral amputation (tfa) run in a prosthesis with an unlocked prosthetic knee, while others choose to run with a locked prosthetic knee to increase stability. research regarding running with an unlocked knee (uk) versus a locked knee (lk), with respect to energy efficiency, is limited and might be enhanced by characterization of the impact of knee condition on kinematics. objective: to investigate the effect of an uk versus lk on hip kinematics, energy efficiency, and running speed. methodology: five male novice runners with unilateral tfa completed one three-minute selfselected running speed (ssrs) trial and three peak speed trials per knee condition. hip kinematics, energy efficiency, and running speed were compared between conditions. findings: four of the five subjects exhibited a fast walk, rather than a consistent run. hip flexion increased for all subjects and hip abduction decreased for four subjects during swing phase for the uk condition. hip kinematic asymmetry was reduced for the uk condition in the sagittal plane for four individuals; hip kinematic asymmetry was also reduced in the frontal plane for the uk condition for three of these individuals. mean energy efficiency was better for the uk condition (uk: 0.282 mlo2/kg/m, lk: 0.328 mlo2/kg/m). peak running speed did not differ significantly between knee conditions (uk: 1.47 m/s, lk:1.32 m/s). conclusions: for novice recreational runners with unilateral transfemoral amputation, the uk condition resulted in improved energy efficiency and enhanced kinematic symmetry, despite comparable peak speed relative to the lk condition. therefore the uk condition may be advantageous for mid-range distance running. article info received: june 14, 2020 accepted: september 7, 2020 published: september 16, 2020 citation blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i 2.34481 keywords kinematic, gait analysis, amputation, prosthesis, running, energy efficiency, gait symmetry, prosthetic knee, lower limb amputation * corresponding author: natalie blakeley, department of biomedical engineering, marquette university, milwaukee, usa. e-mail: blakeley.natalie@gmail.com orcid: https://orcid.org/0000-0002-2066-4096 https://doi.org/10.33137/cpoj.v3i2.34481 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i2.34481 https://doi.org/10.33137/cpoj.v3i2.34481 https://orcid.org/0000-0002-2066-4096 https://orcid.org/0000-0002-2066-4096 2 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 issn: 2561-987x effects of prosthetic knee condition during attempted running blakeley et al. 2020 cpoj the effect of knee condition on oxygen consumption and running speed has been minimally investigated and results to date have been contradictory. for two experienced runners with tfa wearing rsps, wening and stockwell reported that running without a prosthetic knee (no-knee condition) is more efficient based on level treadmill running trials at progressively increasing speeds.3 both subjects ran for a prolonged period and achieved faster peak speeds when running in the no-knee condition. one subject demonstrated reduced peak vo2 and a faster speed for the no-knee condition, suggesting decreased energy efficiency. the other subject achieved a faster speed, but with an increased peak vo2, for the no-knee condition. although wening and stockwell reported the no-knee condition was more energy efficient, as running speed was not controlled, this finding is inconclusive. in contrast, highsmith et al. who tested four experienced runners with tfa reported that the unlocked knee (uk) condition was more energy efficient than the no-knee condition.2 both self-selected running speed (ssrs) and peak speed tended to increase for the uk condition, although not significantly.2 however, mean oxygen consumption was only reduced for five of eight running speeds for the uk condition and prosthesis mass was not controlled. the potential variation in oxygen consumption with knee condition for runners with unilateral tfa may be related to hip kinematics as circumduction and increased hip abduction decrease energy efficiency due to the lateral shift in the center of gravity.5 however, hip kinematics for individuals with unilateral tfa running with a rsp have not been reported to date. the goal of this study was to investigate whether a prosthetic knee unit should be unlocked or locked for individuals with unilateral tfa during recreational running on a treadmill based on hip kinematics, energy efficiency, and running speed. running with a locked prosthetic knee is anticipated to introduce circumduction of the prosthetic limb for ground clearance. for the two knee conditions, the following results are anticipated: 1) increased prosthetic limb hip flexion and reduced hip abduction during swing when running in the uk condition, 2) reduced frontal and sagittal plane interlimb asymmetry of the hip during swing phase when running in the uk condition, 3) better energy efficiency when running with the uk, and 4) faster peak running speed for the uk condition. the population of tfa who currently run is small. to increase the sample size, our target population was novice runners, tfas interested in extending their exercise regimen and potential fitness level, and trialing a running prosthesis. these individuals and their prosthetists might benefit from these trials and the related objective data acquired. methodology five male subjects participated in the study (table 1). subject inclusion criteria were: unilateral transfemoral amputation, k3 to k4 activity level, 18-65 years, good general health, novice runners or individuals with interest and capability (as assessed by their physician or prosthetist), and body weight less than 100 kg (weight limit for the running prosthesis6). individuals with balance disorders or neurological conditions that would adversely impact running, residual limb skin breakdown, or elevated vacuum suspension (incompatible with rsp) were excluded. the study protocol was approved by the affiliated institutional review board (approval number hr-3249) and written informed consent was solicited and obtained for each subject prior to study participation. an ottobock (duderstadt germany) rsp consisting of the prosthetic socket, the 3s80 modular sport knee joint and either the ie90 springlite sprinter foot (subjects 1, 2 and 4) or the ie91 runner foot (subjects 3 and 5) was used by all subjects. each subject retained their original socket for both knee conditions. for subjects who did not own the ottobock rsp, a fitting session was conducted by a collaborating certified prosthetist. the manual lock of the 3s80 knee was either locked (lk) or unlocked (uk), depending on the knee condition. due to time constraints (participant, prosthetist, laboratory, and loaned rsp’s), a single training session (60-90 min) was conducted by the investigator to familiarize the subject with the equipment, test environment, and protocol as well as to determine the subject’s ssrs in the uk and lk conditions. the treadmill training session included walking in both knee conditions, gradually progressing to a run at a pace dictated by the subject. running at a steady-state speed was practiced for 1 to 3 minutes. peak speed trials in each knee condition were conducted to familiarize the subject with the protocol. once the subject verbally acknowledged they felt comfortable running in both knee conditions, the training session was concluded. a minimum of 72 hours post training, a single 3-4 hour testing session was conducted. running trials were conducted on an instrumented split-belt treadmill (woodway, waukesha, wi) while subjects were secured in a fall-arrest, safety harness. subjects completed a warm-up period; the specific duration and activities (i.e., uk or lk, walking or running) were at the discretion of the subject. the warm-up period included a confirmatory determination of ssrs. the ssrs from the testing session was within 0.13 m/s of the training session ssrs for all subjects. two three-minute running trials at ssrs were conducted (one per knee condition) followed by six peak speed running trials (three per knee condition) with a minimum of ten minutes rest between trials.7 subjects were permitted a rest duration greater than 10 minutes, but all declined the extended time. for the three-minute running trials at ssrs, the treadmill was accelerated from rest to a comfortable walking speed and then increased to the subject’s ssrs for the respective knee condition at a rate dictated by the subject. https://doi.org/10.33137/cpoj.v3i2.34481 3 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 issn: 2561-987x effects of prosthetic knee condition during attempted running blakeley et al. 2020 cpoj the peak speed trials commenced in a similar manner after the ssrs was achieved: the speed was increased by 0.089 m/s every 3 seconds until the subject indicated they wanted to stop, pressed the emergency stop button, or engaged the safety harness. to minimize knee condition changes, the running trial order was not randomized. switching knee conditions repeatedly would have increased the subjects’ time burden, and randomizing the knee condition test order may adversely affect the subject’s confidence. the uk condition was tested first as subjects routinely walk with an unlocked knee, thereby increasing their initial confidence and security during testing. additionally, highsmith et al. found the uk knee was more energy efficient,2 thus the uk condition sprints were completed last. the test order was ssrs uk, ssrs lk, peak speed lk, followed by peak speed uk (figure 1). three-minute running trials were conducted first to decrease the effect of fatigue on metabolic results. three peak speed trials with the knee locked were completed prior to peak speed testing in the uk condition, as the subject had just completed sub-maximal running with this knee condition. peak speed was determined by accelerating the treadmill from rest to a comfortable walking speed and then increasing speed to the subject’s ssrs for the associated knee condition. the speed then increased by 0.089 m/s every 3 seconds until the subject indicated they wanted to stop, pressed the emergency stop button, or engaged the safety harness. the final speed achieved prior to the occurrence of one of these events was recorded as the trial’s peak speed. at the conclusion of the testing session, subjects were asked to identify the preferred knee condition (uk or lk) for distance running and sprinting. a 13-camera motion capture system (optitrack, corvallis, or) was used to acquire kinematic data (120 hz, low pass filtered with a fourth order butterworth, cut-off frequency of 6 hz 8,9) during the three-minute running trials. the filter cutoff frequency was determined based on a fast fourier transform of the left and right heel and anterior superior iliac spine marker position data. thirty five retro-reflective markers were secured to the subject based on a conventional gait model, modified for the prosthetic limb,4,10 using visual 3d software (version 6, c-motion, germantown, md). consistent with the conventional gait model, the hip angle was defined as the thigh relative to the pelvis. markers were placed on the sacrum and bilaterally positioned on the iliac crest, anterior superior iliac spine, greater trochanter, lateral femoral epicondyle, medial femoral epicondyle, tibial tuberosity, lateral malleolus, subject 1 subject 2 subject 3 subject 4 subject 5 mean (sd) age (years) 59 52 57 54 56 55.6 (2.42) mass (without prosthesis, kg) 72.8 93.0 87.4 82.5 93.4 85.2 (8.54) height (with rsp, cm) 184.0 186.0 178.0 185.5 176.5 182 (3.96) residual limb length* (cm) 21 16 38 31 39 29 (9.14) amputated side right left left right left cause of amputation cancer cancer trauma trauma trauma time post amputation (years) 49 47 5 6 6 22.6 (20.75) running experience everyday prosthesis short sprints during various sports (volleyball, tennis, basketball) within 1 month of testing, knee unlocked none none none weekly fast walk 1.5-2 miles, on treadmill within 1 month of testing, knee unlocked everyday prosthetic componentry suspension: suction knee: genium foot: triton vertical shock suspension: suction knee: x3 foot: triton vertical shock suspension: suction knee: c-leg foot: triton 1c60 suspension: elevated vacuum knee: x3 foot: triton harmony suspension: suction knee: genium foot: trias plus running experience with rsp for the 2 weeks prior to testing, over ground running with knee unlocked and locked one day per year, over ground with knee unlocked and locked for the 3 months prior to testing, 34x per week on alterg anti-gravity treadmill with knee unlocked for the 3 months prior to testing, over ground with knee locked none table 1: subject characteristics and running experience. * distance from the greater trochanter to the most distal point on the femur (as determined by palpation). https://doi.org/10.33137/cpoj.v3i2.34481 4 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 issn: 2561-987x effects of prosthetic knee condition during attempted running blakeley et al. 2020 cpoj medial malleolus, fifth metatarsal, second metatarsal, and calcaneus. marker placements on the rsp are shown in figure 2. a static trial was conducted for each subject and knee condition to define the local coordinate systems. figure 1: flow chart overview of the running trials for the test protocol. to determine stride cycle events, vertical force data were collected (1200 hz) from the instrumented split belt treadmill, low pass filtered (zero phase 8th order butterworth filter, cutoff of 12 hz13), and down sampled to match the sampling frequency for the kinematic data; an amplitude threshold of 44.5 n was implemented to define heel strike (hs) and toe-off (to) events.14 a custom matlab (version: 9.1.0.441655, the mathworks, inc., natick, ma) script was written for vertical force data processing. specific kinematic parameters, extracted bilaterally for analysis, included peak hip flexion and peak hip abduction during swing phase. to assess the asymmetry of these kinematic parameters between the prosthetic and intact limbs during each knee condition, the interlimb asymmetry (ia) index (equation 1)15 was calculated using microsoft excel (version 1908, microsoft corporation, redmond, wa) for discrete stride cycles in the middle 45-second period of the three-minute ssrs trial. stride cycles were excluded if marker drop-out exceeded 10 frames and affected the calculated kinematic parameter of interest. for a given subject and kinematic parameter, the number of stride cycles (6-17 cycles) retained for analysis was the same between knee conditions, randomly omitting the extra stride cycles for the knee condition with more cycles. for each subject and knee condition, the mean and standard deviations were calculated across all included stride cycles in the analyzed time period for ia for peak hip flexion and abduction during swing phase, respectively. equation 1: 𝐼𝐴 = ( 𝑋𝑖𝑛𝑡𝑎𝑐𝑡−𝑋𝑝𝑟𝑜𝑠𝑡ℎ𝑒𝑡𝑖𝑐 𝑋𝑖𝑛𝑡𝑎𝑐𝑡 +𝑋𝑝𝑟𝑜𝑠𝑡ℎ𝑒𝑡𝑖𝑐 ) ∗ 100% xprosthetic and xintact represent the specific kinematic measures (peak swing phase hip flexion and abduction) for the prosthetic and intact limbs, respectively. an ia index value of 0 represents symmetry; negative ia values indicate that the parameter value for the prosthetic limb exceeded that for the intact limb. the percentage of asymmetry is reflected by the ia magnitude (e.g. an ia index of -20 and +20 represent the same magnitude of asymmetry). figure 2: marker placements on the 1e90 sprinter foot (top) and 1e91 runner foot (bottom) (figure adapted from ottobock11,12). not pictured: “heel” marker placed posteriorly at the most acute radius of the foot. • kinematic data: middle 45 sec period only • ssrs • re: during steady state period only, 40-120 sec • peak speed • preferred knee condition for distance, sprinting 3 min run with knee unlocked max speed with knee unlocked 3 min run with knee locked max speed with knee locked max speed with knee locked max speed with knee locked max speed with knee unlocked max speed with knee unlocked minimum 10 min. rest minimum 10 min. rest minimum 10 min. rest minimum 10 min. rest minimum 10 min. rest minimum 10 min. rest minimum 10 min. rest l knee lat. l shank sup. l ankle l tib. tuberosity l lat. ankle inf. l med. ankle inf. l foot med. l foot lat. l toe l foot ant. l toe l foot lat. l foot med. l foot ant. l lat. ankle inf. l med. ankle inf. l ankle l shank sup. l tib. tuberosity l knee lat. https://doi.org/10.33137/cpoj.v3i2.34481 5 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 issn: 2561-987x effects of prosthetic knee condition during attempted running blakeley et al. 2020 cpoj vo2 measurements were collected breath-by-breath using the k4b2 portable metabolic system (cosmed usa inc, chicago il) during the full three-minute trials for both knee conditions. vo2 data were averaged over 20 second intervals for the entire data series. running economy (re), a measure of energy efficiency during running, was calculated from the steady-state vo2 portion of the trial. the steady-state portion of the vo2 was defined as a change in vo2 of less than 100 ml/min.16 based on this definition, all participants achieved steady-state for both knee conditions with durations ranging from 40 to 120 seconds. re was calculated as the ratio of the body-mass normalized steadystate vo2 to the ssrs for the corresponding three-minute trial. re was calculated both inclusive and exclusive of prosthesis mass. statistical analyses statistical analyses were conducted using spss (v 24.0, ibm inc., armonk, ny). the shapiro-wilk test (p=0.05) was used to assess data normality for all variables. the uk condition was anticipated to reduce hip kinematic pathologies during swing. swing phase peak prosthetic limb hip flexion, abduction, and hip frontal and sagittal plane interlimb asymmetry were tested with two-tailed paired ttests (p=0.05, if normally distributed data) or the wilcoxon signed-rank test (p=0.05, if non-normally distributed data). all kinematic variables were assessed on a single-subject basis in a separate test for each knee condition, using all retained stride cycles. thus, there were 6-17 data points per statistical test. the corresponding effect size was calculated using cohen’s d (normally distributed data) and equation 2 (non-normally distributed data): equation 2: r=z/√n where r represents effect size, z represents the test statistic, and n represents the number of samples. in contrast to the kinematic parameters, single values of re and peak speed were available for each knee condition and subject. these data were assessed on an inter-subject basis using a paired t-test (p=0.05). these group statistics, while statistically significant, are referred to as “trends” due to the small sample size. results due to the novice running status of the recruited subjects, only subject 1 was able to run (i.e. exhibit periods where both feet were airborne simultaneously) consistently throughout the ssrs and peak running speed trials. subjects 2-5 all exhibited a fast walk. subjects 1 and 2 did not require the use of the handrails while subjects 3-5 used the handrails consistently throughout all the trials for both knee conditions. the uk condition was preferred for all subjects for distance running and subjects 2 and 4 preferred the lk condition for sprinting. kinematics: statistically significant single-subject differences in maximum hip flexion during swing were found between knee conditions across all subjects. peak hip flexion of the prosthetic limb increased during swing with the uk condition for all subjects (table 2, figure 3, see nelson17 for all kinematic graphs). a statistically significant difference in peak ia for the hip in the sagittal plane between knee conditions was found for each subject (table 2). for four subjects (1-4), the prosthetic hip abduction during swing increased (greater negative angle) from the uk condition to the lk condition (table 3, figure 3, see nelson17 for all kinematic graphs). for all subjects, peak ia for the hip in the frontal plane during swing differed significantly between knee conditions (table 3); in terms of magnitude, ia decreased for three subjects (1, 2, and 4) for the uk condition, reflecting increased symmetry for this knee condition. subject 1 subject 2 subject 3 subject 4 subject 5 uk lk uk lk uk lk uk lk uk lk prosthetic limb peak hip flexion (°) 45.7 (1.05) 27.4 (1.34) 48.2 (2.72) 31.8 (2.22) 60.3 (2.03) 57.2 (4.25) 53.5 (1.50) 40.6 (1.76) 53.8 (1.57) 51.8 (1.72) +p <0.001, effect size: 10.80 [6 cycles] +p <0.001, effect size: 4.29 [7 cycles] +p =0.012, effect size: 0.99 [10 cycles] +p <0.001, effect size: 6.52 [17 cycles] +p = 0.001, effect size:0.26 [17 cycles] ia for peak hip flexion (%) -2.87 (1.35) 25.90 (2.54) -4.58 (2.49) 16.40 (4.10) 0.29 (2.50) 9.29 (3.73) -3.58 (1.67) 9.10 (2.37) -2.10 (1.95) 0.65 (2.10) *p = 0.001, effect size:1.34 [6 cycles] +p <0.001, effect size:3.36 [7 cycles] +p = 0.006, effect size:1.84 [6 cycles] +p <0.001, effect size:4.62 [15 cycles] +p = 0.001, effect size:1.09 [15 cycles] table 2: sagittal plane hip kinematics (mean (sd)) during swing phase for select strides in the middle 45 seconds of the three-minute selfselected running speed trial for each subject for each knee condition. bold values denote statistically significant single-subject differences (0.05 level) between knee conditions. + denotes a two-tailed paired t-test was conducted (normally distributed data). * denotes the wilcoxon signed-rank test was conducted (non-normally distributed data). uk = unlocked knee, lk = locked knee https://doi.org/10.33137/cpoj.v3i2.34481 6 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 issn: 2561-987x effects of prosthetic knee condition during attempted running blakeley et al. 2020 cpoj e intact limb prosthetic limb unlocked knee condition unlocked knee condition locked knee condition h ip f le x io n ( + ) / e x te n s io n ( -) ( d e g re e s ) h ip f le x io n ( + ) / e x te n s io n ( -) ( d e g re e s ) h ip a d d u c ti o n ( + )/ a b d u c ti o n ( -) ( d e g re e s ) h ip a d d u c ti o n ( + )/ a b d u c ti o n ( -) ( d e g re e s ) figure 3: mean (middle 45 seconds) hip motion in the sagittal (top) and frontal planes (bottom) for subject 1 during the self-selected running speed trial in the unlocked (left) and locked (right) knee conditions. vertical lines denote toe-off. subject 1 subject 2 subject 3 subject 4 subject 5 uk lk uk lk uk lk uk lk uk lk prosthetic limb peak hip abduction (°) -13.2 (0.783) -20.7 (0.968) -7.5 (0.651) -18.4 (1.27) -15.4 (1.95) -18.4 (2.63) -5.5 (0.753) -16.1 (1.38) -15.5 (1.64) -13.7 (1.48) +p <0.001 effect size: 5.23 *p = 0.018 effect size: 0.09 +p = 0.017 effect size: 0.93 +p <0.001 effect size: 6.41 +p <0.001 effect size:1.18 ia for peak hip abduction (%) -19.4 (4.53) -43.6 (5.24) 14.8 (7.36) -20.9 (8.93) -83.0 (4.09) -65.0 (4.30) 22.5 (6.52) -27.3 (6.45) -32.4 (9.73) -15.6 (7.70) +p = 0.002 effect size:2.39 *p = 0.001 effect size:1.24 +p = 0.003 effect size:2.26 +p <0.001 effect size:5.35 *p <0.001 effect size:1.40 table 3: frontal plane hip kinematics (mean (sd)) during swing phase for select strides for the middle 45 seconds of the three-minute selfselected running speed trial for each subject for each knee condition. bold values denote statistically significant single-subject differences (0.05 level) between knee conditions. + denotes a two-tailed paired t-test was conducted (normally distributed data). * denotes the wilcoxon signedrank test was conducted (non-normally distributed data).uk = unlocked knee, lk = locked knee locked knee condition subject 1 subject 2 subject 3 subject 4 subject 5 group mean (sd) uk lk uk lk uk lk uk lk uk lk uk lk re (mlo2/kg/ m) 0.301 0.348 0.290 0.286 0.266 0.305 0.332 0.430 0.223 0.270 0.282 (0.037) 0.328 (0.057) table 4: running economy during the three-minute ssrs trials; normalization is exclusive of prosthesis mass. https://doi.org/10.33137/cpoj.v3i2.34481 7 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 issn: 2561-987x effects of prosthetic knee condition during attempted running blakeley et al. 2020 cpoj energy efficiency a trend was found for differences in re between knee conditions, regardless of whether prosthesis mass was included or excluded in the normalization. mean re values were reduced for the uk condition for the re calculated exclusive of prosthesis mass (table 4, see nelson17 for re normalized inclusive of prosthesis mass). running speed ssrs ranged from 0.890 to 1.79 m/s (mean ssrs: uk=1.47(sd=0.260) m/s, lk=1.32 (sd=0.246) m/s). all five subjects exhibited faster ssrs for the uk condition (table 5). peak running speed ranged from 2.15 to 3.30 m/s (average peak speed: uk=2.72 (sd=0.450) m/s, lk=2.61 (sd=0.320) m/s). discussion research regarding the effect of knee condition on lower extremity kinematics for individuals with unilateral tfa is limited; the observed kinematic data cannot be contrasted with the literature. for novice runners with unilateral tfa, lk running can be characterized by reduced peak hip flexion of the prosthetic limb and increased hip abduction during swing (table 2, table 3). the more extended and abducted prosthetic hip during swing is likely attributed to circumduction of the prosthetic limb to provide floor clearance. in contrast to the uk condition for which knee flexion assists with floor clearance in the sagittal plane, lk running requires both sagittal and frontal plane hip motion to provide clearance. future work might include an analysis of the bilateral knee kinematics to provide more insight into how foot clearance is accomplished. although swing phase pelvic kinematic data were not presented, it was collected and can assist in the interpretation of the hip kinematic data. the pelvis was typically tilted anteriorly during running in the lk condition. for subjects 3-5, this may be attributed to their leaning on the handrails for support. pelvic motion in the frontal plane was variable: subjects 1-3 exhibited ipsilateral tilt (pelvis tilted downwards on the prosthetic limb side) during lk running and subjects 4 and 5 exhibited contralateral tilt (pelvis tilted upwards on the prosthetic limb side) during lk running. all subjects exhibited external pelvic rotation (rotated away from center of body) on the prosthetic limb side. specifically, subject 5 demonstrated approximately 17° of external pelvic rotation compared to 3°-11° external pelvic rotation for subjects 1-4. although all subjects exhibited a decrease in peak swing phase hip flexion during lk running, this difference was relatively small for subjects 3 and 5 (2-3°) relative to the other subjects (13-18°). during lk running, hip abduction of the prosthetic limb increased during the swing phase by 3° to 11° for subjects 1 and 4, potentially due to the circumduction of the prosthetic limb for floor clearance during lk running. it should be noted that because the hip angle was defined as the thigh relative to the pelvis, an increase in hip abduction may be attributed, at least in part, to upwards pelvic obliquity. subject 5 did not exhibit an increase in swing phase hip abduction with the lk condition potentially due to adopting a different strategy to clear the prosthetic limb as he was one of the least experienced runners with an rsp. the unanticipated decrease in hip abduction with the lk condition may have been inadvertently masked by defining the hip angle as the thigh relative to pelvis. for example, if the trunk and pelvis were leaning away from the swing limb to aid foot clearance, no increased hip abduction would be observed. the anticipated increase in prosthetic limb hip flexion during swing was not observed, nor was the anticipated reduced hip abduction during swing observed with the uk condition. the uk condition resulted in better symmetry in peak hip flexion (maximum hip angle) for four subjects (1-4) as indicated by the reduced ia magnitude compared to the lk condition (table 2). in the frontal plane, ia differed significantly on a singlesubject basis between knee conditions for peak hip abduction (minimum hip angle) during swing phase for all subjects. three subjects (1, 2, 4) demonstrated improved symmetry during uk running. in contrast, subjects 3 and 5 exhibited improved frontal plane hip symmetry during swing for the lk condition. the anticipated reduced hip ia in the frontal and sagittal planes when running in the uk condition was therefore not observed. a possible explanation for this unanticipated result is that subjects 3 and 5 adopted an altered circumduction pattern. for subjects 1, 2, and 4, prosthetic limb hip flexion occurred approximately 13-22% stride cycle later than hip abduction. subjects 3 and 5, however, initiated hip flexion and abduction simultaneously. subject 1 subject 2 subject 3 subject 4 subject 5 group mean (sd) uk lk uk lk uk lk uk lk uk lk uk lk ssrs (m/s) 1.34 1.29 1.43 1.34 1.79 1.48 1.07 0.890 1.70 1.61 1.47 (0.260) 1.32 (0.246) peak speed (m/s) 2.24 2.32 2.86 2.86 3.30 2.95 2.15 2.15 3.04 2.77 2.72 (0.450) 2.61 (0.320) table 5: ssrs and peak speed (maximum value of three trials) for each knee condition. https://doi.org/10.33137/cpoj.v3i2.34481 8 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 issn: 2561-987x effects of prosthetic knee condition during attempted running blakeley et al. 2020 cpoj for subject 3, this manifested as increased hip flexion and reduced hip abduction during circumduction, leading to a narrower circumduction path. this may be due to his experience with uk running (table 1) leading to a habit of pulling the prosthetic limb directly underneath his body, as opposed to circumduction. in contrast, subject 5 externally rotated his pelvis on the prosthetic limb side just prior to toeoff which may have facilitated the simultaneous hip flexion and abduction. this may be a technique to achieve circumduction with decreased hip abductor muscle activity on the intact limb. it is important to note that the socket design was kept consistent between knee conditions for each subject; therefore, the socket design did not influence results on an individual subject basis, but it may have influenced results between subjects. additionally, the length of the prosthesis was not adjusted when switching between knee conditions. a prosthetist may elect to shorten the prosthesis when leaving the knee locked to assist in limb clearance during swing phase. thus, the observed increased hip abduction during lk running may be attributed in part to overall prosthesis length. while not statistically significant, a trend was found for grouped-subject differences also observed in re (table 4) across subjects. mean re values were improved for the uk condition, indicating that for this population of novice runners with tfa, running with an uk was more efficient than running with a lk, as expected. these results are consistent with highsmith et al.2 who observed reduced mean oxygen consumption for the uk condition for five of eight running speed stages (1.122.01 m/s). the decreased energy efficiency observed for the lk condition is likely attributed to the pathologic prosthetic limb circumduction strategy adopted to provide floor clearance. the improved re with the three-minute running trial also supports the uk condition preference for distance running for all five subjects. finally, for the novice runners with unilateral tfa in this study, the average peak running speed was faster for the uk condition (unlocked: 2.72 ± 0.450 m/s, locked: 2.61 ± 0.320 m/s). contrary to initial expectations, only two subjects (3 and 5) ran faster in the uk condition. the results were consistent with highsmith et al.2 who also observed no significant difference in peak running speed with knee condition for runners with unilateral tfa. these findings, however, contradict wening and stockwell3 who reported faster speeds for the no-knee condition. neither study, however, included statistical analyses as the investigations included just two and one subject, respectively. these previous studies tested experienced runners with unilateral tfa for a much longer duration (10-17 minutes2,3 versus 3060 seconds). their protocols therefore measured peak endurance speed rather than sprinting capacity. similarly, the mean ssrs for the uk (1.47 (sd=0.260) m/s) was faster than for the lk condition (1.32 (sd= 0.240) m/s). the faster ssrs for the uk condition may indicate the uk is advantageous for treadmill running, provided that the subject has the endurance and cognitive focus to prevent knee buckling. in contrast, highsmith et al. did not find significant differences in ssrs between knee conditions. limitations a primary limitation of this study was the small sample size. post hoc power analysis indicated the power associated with the peak speed parameter was only 16.8%. given the lack of statistically significant differences in peak speed with knee condition, variations in test methodology between the current study and previous studies, definitive conclusions regarding which knee condition facilitates increased speed cannot be stated. another limitation is the small magnitude of observed differences in hip kinematics between knee conditions. while these differences were statistically significant, they are likely not clinically relevant. a 2°-3° difference in peak hip flexion (subject 5) and peak hip abduction (subjects 3 and 5) between knee conditions may have been imperceptible to the subject. similarly, the relatively short duration (three minutes) of the ssrs trials likely limits the potential clinical and/or realworld relevance of the study findings. while the differences in ssrs were modest, such differences may be relevant if sustained during increased duration running trials. lastly, subject 1 was the sole participant who actually “ran”, exhibiting periods during which both feet were airborne simultaneously. the ambulation of the remaining subjects might be more accurately described as a “fast walk”, with a few cycles of true running interspersed. future protocols might incorporate more extensive training for both knee conditions, prior to data collection, to more effectively assess subjects’ true running performance. additionally, a second test session to determine repeatability of the novice runners’ performance would have been ideal; however, time constraints did not permit this. clinical recommendations: running with a lk increases stability of the prosthesis, decreasing fall risk and cognitive load3; these factors are likely important during running for prolonged periods and longer distances. for recreational, short distance running on a treadmill, the results of this study suggest that the uk condition may be advantageous for novice runners with unilateral tfa. the lk condition resulted in decreased energy efficiency and a slower ssrs. the uk condition may also decrease risk of musculoskeletal injury, as this knee condition resulted in minimal gait pathologies. the lk condition required circumduction for floor clearance, a gait pathology that https://doi.org/10.33137/cpoj.v3i2.34481 9 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 issn: 2561-987x effects of prosthetic knee condition during attempted running blakeley et al. 2020 cpoj impacts hip kinematics in multiple planes and may also affect pelvic and trunk motion. conclusion hip flexion decreased for all subjects and hip abduction increased for four subjects during swing when individuals with unilateral tfa ran with a lk due to compensatory circumduction to assist with foot clearance. this circumduction increased ia during swing for the peak hip flexion and peak hip abduction measures and may contribute to the decreased energy efficiency observed during lk running. based on these results and the relatively short running duration in this study, the uk condition is recommended for novice runners with unilateral tfa when running short distances on a treadmill. acknowledgements the authors would like to thank ottobock, duderstadt, germany for providing the running specific prostheses for this study. the authors would also like to thank david del toro, md for his assistance with study concept and subject recruitment, paula papanek, ph.d. and toni uhrich, ms for assistance with energy cost methodology and analysis, and molly erickson, scott crawford, and courtney jack for their assistance with subject testing and data analysis. the authors would also like to thank collaborating prosthetists (herb bohn, cp, john mooney, cpo, tom current, cpo, joshua dezek, cp, and dennis farrell, cp) for their active involvement in subject recruitment and prosthetic fitting. lastly, the authors would like to acknowledge laurens holmes, md, ph.d, and rebekah walker, ph.d for their expertise regarding statistical analysis. declaration of conflicting interests the authors declare that there is no conflict of interest. author contribution natalie blakeley: designed the study, acquired the data, analyzed the data, interpreted the data, and drafted the manuscript. barbara silver-thorn: designed the study, interpreted the data, and revised the manuscript. janelle a. cross: assisted in the design of the study, interpreted the data, and revised the manuscript. sources of support clinical and translational science institute pilot translational and clinical studies program start-up project award. this award is supported by grant ul1tr001436 from the clinical and translational science award (ctsa) program of the national center for research resources and the national center for advancing translational sciences. ethical approval the study protocol was approved by the affiliated institutional review board (approval number hr-3249) and written informed consent was solicited and obtained for each subject prior to study participation. references 1.mengelkoch lj, kahle jt, highsmith mj. energy costs and performance of transfemoral amputees and non-amputees during walking and running: a pilot study. prosthet orthot int. 2016;41(5):484–491. doi: 10.1177/0309364616677650 2.highsmith mj, kahle jt, miro rm, mengelkoch lj. bioenergetic differences during walking and running in transfemoral amputee runners using articulating and non-articulating knee prostheses. technol innov. 2016;18(2–3):159–165. doi: 10.21300/18.23.2016.159 3.wening j, stockwell m. oxygen consumption and prosthetic moments for two trans-femoral amputees running with and without a knee. american academy of orthotists & prosthetists, 38th academy annual meeting and scientific symposium, march 21-24, 2012. 4.diebal-lee ar, kuenzi rs, rábago ca. return to running following a knee disarticulation amputation: a case report. int j sports phys ther. 2017;12(4):655–669. 5.lusardi m, jorge m, nielson c. orthotics and prosthetics in rehabilitation-e-book, elsevier health sciences; 2013; [cited 2018 jan 16]. available from: https://www.elsevier.com/books/orthoticsand-prosthetics-in-rehabilitation/lusardi/978-1-4557-4567-8 6.fitness knee 3s80/3s80=1 [internet]. ottobock; [cited 2018 jan 16]. available from: https://shop.ottobock.us/media/pdf/13503_3s80_3s80-1_ss.pdf 7.beck on, taboga p, grabowski am. prosthetic model, but not stiffness or height, affects the metabolic cost of running for athletes with unilateral transtibial amputations. j appl physiol. 2017; 1;123(1):38-48. doi: 10.1152/japplphysiol.00896.2016 8.hobara h, baum bs, kwon h-j, miller rh, ogata t, kim yh, et al. amputee locomotion: spring-like leg behavior and stiffness regulation using running-specific prostheses. j biomech. 2013;46(14):2483–2489. doi: 10.1016/j.jbiomech.2013.07.009 9.beck on, taboga p, grabowski am. characterizing the mechanical properties of running-specific prostheses. plos one. 2016;11(12):e0168298. doi: 10.1371/journal.pone.0168298 10.robertson dge, caldwell ge, hamill j, kamen g, whittlesey sn. research methods in biomchanics. 2nd ed. human kinetics; 2014. 428 p. 11.springlite sprinter [internet]. ottobock; [cited 2018 jan 16]. available from: https://www.ottobock.co.th/prosthetics/lowerextremity/solution-overview/running-prosthesis-system/ 12.1e91 runner [internet]. ottobock; [cited 2018 jan 18]. available from: http://professionals.ottobockus.com/prosthetics/lower-limbprosthetics/fitness-prosthetics/1e91-runner/p/1e91 13.riley po, paolini g, della croce u, paylo kw, kerrigan dc. a kinematic and kinetic comparison of overground and treadmill walking in healthy subjects. gait posture. 2007;26(1):17–24. doi: 10.1016/j.gaitpost.2006.07.003 14.grabowski am, mcgowan cp, mcdermott wj, beale mt, kram r, herr hm. running-specific prostheses limit ground-force during sprinting. biol lett. 2010;6(2):201–4. doi: 10.1098/rsbl.2009.0729 https://doi.org/10.33137/cpoj.v3i2.34481 10 blakeley n., silver-thorn b., cross j.a. investigation of the effects of prosthetic knee condition for individuals with transfemoral amputation during attempted running. canadian prosthetics & orthotics journal. 2020; volume 3, issue 2, no.3. https://doi.org/10.33137/cpoj.v3i2.34481 issn: 2561-987x effects of prosthetic knee condition during attempted running blakeley et al. 2020 cpoj 15.bishop c, read p, lake j, chavda s, turner a. inter-limb asymmetries: understanding how to calculate differences from bilateral and unilateral tests. strength cond j. 2018;40:1–6. doi: 10.1519/ssc.0000000000000371 16.fletcher jr, esau sp, macintosh br. economy of running: beyond the measurement of oxygen uptake. j appl physiol. 2009;107(6):1918–22. doi: 10.1152/japplphysiol.00307.2009 17.nelson n. investigation of the effects of prosthetic knee condition on novice transfemoral amputee runners. master’s theses. marquette university; 2018. available from: https://epublications.marquette.edu/theses_open/467 https://doi.org/10.33137/cpoj.v3i2.34481 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives kogler gf, hovorka cf. academia’s role to drive change in the orthotics and prosthetics profession. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.21. https://doi.org/10.33137/cpoj.v4i2.36673 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.36673 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 kogler gf, hovorka cf. academia’s role to drive change in the orthotics and prosthetics profession. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.21. https://doi.org/10.33137/cpoj.v4i2.36673 stakeholder perspectives academia’s role to drive change in the orthotics and prosthetics profession kogler gf.1*, hovorka cf.2 1 orthotics and prosthetics unit, kennesaw state university, kennesaw, usa. 2 orthotics and prosthetics program, department of rehabilitative sciences, east tennessee state university, johnson city, usa. introduction in this position paper, we describe the important role academia plays in shaping the orthotics and prosthetics (o&p) profession. in this approach, we present the challenges and proposed strategies for academia to prepare the next generation of professionals to continue to evolve and define the value of o&p care. this process will require future o&p professionals to embrace and integrate data driven approaches including new and emerging technologies as a therapeutic treatment for habilitation and rehabilitation. factors influencing change in healthcare the profession of o&p, like many health professions, is under intense pressure to provide cost-effective treatments and quantifiable health outcomes. in the united states, where healthcare expenditures represent nearly 18% of gross domestic product 1 healthcare is confronted with an impending paradigm shift. for the profession of o&p this translates into several challenges such as the provision of services for an increasing number of patients by a relatively small workforce of certified practitioners delivering these services at a reduced cost with the expectation of significant, meaningful and measurable value (e.g., clinical outcomes). pivotal changes are needed in the way o&p services are provided. to remain competitive, the o&p profession will need to move away from the traditional laborintensive manufacturing processes and the typical clinical open access volume 4, issue 2, article no.21. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract this position paper outlines the important role of academia in shaping the orthotics and prosthetics (o&p) profession and preparing for its future. in the united states, most healthcare professions including o&p are under intense pressure to provide cost effective treatments and quantifiable health outcomes. pivotal changes are needed in the way o&p services are provided to remain competitive. this will require the integration of new technologies and data driven processes that have the potential to streamline workflows, reduce errors and inform new methods of clinical care and device manufacturing. academia can lead this change, starting with a restructuring in academic program curricula that will enable the next generation of professionals to cope with multiple demands such as the provision of services for an increasing number of patients by a relatively small workforce of certified practitioners delivering these services at a reduced cost, with the expectation of significant, meaningful, and measurable value. key curricular changes will require replacing traditional labor-intensive and inefficient fabrication methods with the integration of newer technologies (i.e., digital shape capture, digital modeling/rectification and additive manufacturing). improving manufacturing efficiencies will allow greater curricular emphasis on clinical training and education – an area that has traditionally been underemphasized. providing more curricular emphasis on holistic patient care approaches that utilize systematic and evidence-based methods in patient assessment, treatment planning, dosage of o&p technology use, and measurement of patient outcomes is imminent. strengthening o&p professionals’ clinical decision-making skills and decreasing labor-intensive technical fabrication aspects of the curriculum will be critical in moving toward a digital and technology-centric practice model that will enable future practitioners to adapt and survive. citation kogler gf, hovorka cf. academia’s role to drive change in the orthotics and prosthetics profession. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.21. https://doi.org/10.33137/cpoj.v4i2.36673 keywords orthotics, prosthetics, education, curriculum reform, healthcare economics * corresponding author géza f. kogler orthotics and prosthetics unit, kennesaw state university. e-mail: gkogler1@kennesaw.edu orcid id: https://orcid.org/0000-0003-0212-5520 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.36673 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.36673 mailto:gkogler1@kennesaw.edu https://orcid.org/0000-0003-0212-5520 2 kogler gf, hovorka cf. academia’s role to drive change in the orthotics and prosthetics profession. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.21. https://doi.org/10.33137/cpoj.v4i2.36673 issn: 2561-987x academia’s role to drive change kogler & hovorka., 2021 cpoj special s p e c ia l i s s u e patient care processes based on anecdote, trial and error. historically, these processes, which were once accepted when reimbursement for o&p services by third party payers were less rigorous, but they are no longer acceptable or sustainable in modern healthcare. hence, there is a need for the o&p profession to adopt more efficient methods that utilize a systematic and quantifiable framework. emerging evidence in manufacturing of o&p devices suggests that employing computer-augmented approaches, such as digital shape capture and additive, 3d-printing manufacturing methods, may soon make obsolete devices created by hand craftsmanship.2 in addition, the implementation of data science to inform evidence-based clinical decision-making suggests these methods may lead toward improved clinical outcomes and patient value.3,4 other challenges to the o&p profession include a looming workforce shortage;5 increased patient volumes; more complex patients, whose care must include consideration of multiple diagnoses; underrepresented billing codes and insurance practices that require evidence of efficacy6,7 and proof of values-based care8 with no path for reimbursement. if the practitioner workforce deficit cannot meet the demand for services, alternative methods will likely emerge from related medical specialties or leveraged by new business models such as direct-to-consumer orthoses and prostheses. to stay ahead of these challenges, o&p education must build evolving curriculum models that can equip students to evolve along with a rapidly changing technology-driven healthcare environment. an emphasis on subject areas such as 3d modeling/printing, data science, and digital diagnostics (e.g., biomedical sensing) will provide students with a familiarity sufficient for them to “use it, interpret it and explain it”,9 and to understand their impact on decision making and treatment interventions.9 preparing for changes throughout a professional’s lifespan the academic programs that train future professionals in clinical practice, research, and education can fundamentally influence whether the o&p profession’s scope of practice expands or contracts, and its ability to adapt to the factors that drive change. emerging technologies, market forces, regulatory policy, and economic costs are transforming all sectors of healthcare, and these factors have already started to disrupt current practice. to cope with these demands, academic programs in o&p will need to reimagine their curriculum beyond the existing scope of practice in o&p, and will need to work with accreditation agencies (in the us, the commission on accreditation of allied health education programs and its committee on accreditation, the national commission on orthotic and prosthetic education, as well as relevant international organizations) to re-examine and update the core curriculum requirements of the master’s degree10,11 along the lines we have suggested, expanding both graduates' skills and their ability to adapt to future shifts in the delivery of o&p patient care. well-informed analyses of trends in medicine, healthcare, business, computer science, and manufacturing often provide useful forecasts for changes in these fields, and may also provide strategic perspective for o&p educators. brief history of orthotics and prosthetics education in the united states, o&p is evolving from its historical roots as an industry consisting of highly skilled “tradespersons” (i.e., technicians, fitters) to an expanded recognition as an allied healthcare profession. clinical practitioners in o&p possess an entry-level master’s degree and are supported by practitioner assistants and fabricators. over the decades, the evolution from technician to clinician has required updates in the “tools of practice,” from devicecentric, hand-crafted fabrication and fitting to contemporary practice involving greater emphasis on holistic, patientcentered care. this transition involved shifting the focus to clinical diagnostics, patient goal planning, treatment formulation, problem-solving and solution-based patient management. the shift from technician to clinician required a change in the curriculum which continues to evolve today. academic preparation in the clinical sciences (e.g., body systems pathology and clinical conditions, methods of structured patient assessment, and clinical decisionmaking), materials science, and movement sciences were added to the necessary proficiency training in skills such as custom device manufacturing. despite practice analysis data that defines 90% of today’s practitioners as engaged in clinical rather than technical fabrication duties,10 educational programs continue to devote considerable time to device fabrication skills. urgent curricular changes are needed to prepare the next generation of practitioners as the “tools of practice” in o&p move from hand fabrication to digital technologies that enable more efficient, economical, and adaptable processes that can better support contemporary healthcare delivery systems. more expedient and efficient device delivery will be needed to manage a greater number of patients and to cope with shrinking reimbursement for services. this increased demand will likely prompt practice managers to adopt the use of more prefabricated, custom-fitted, and modular o&p systems, and to consider the advantages that 3-d shape capture and additive manufacturing may offer.2,12 in exchange for the time saved by improved fabrication efficiencies, practitioners may be able to devote more time developing clinical patient management skills in areas that have traditionally been less well represented such as structured patient assessment and clinical diagnostics, goal setting, treatment planning and assessment of clinical outcomes. curriculum reform that includes technologies that are readily transferable to o&p and that complement clinical practice courses are strongly justified, according to https://doi.org/10.33137/cpoj.v4i2.36673 3 kogler gf, hovorka cf. academia’s role to drive change in the orthotics and prosthetics profession. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.21. https://doi.org/10.33137/cpoj.v4i2.36673 issn: 2561-987x academia’s role to drive change kogler & hovorka., 2021 cpoj special s p e c ia l i s s u e thimbleby13 who states that “technology drives healthcare more than any other force”. ideally, one would hope that the graduates of o&p programs are empowered to become the next innovators that advance the profession and thereby dictate, in part, the direction in which the profession evolves. the domains of practitioner competency that exist today will have to evolve if we are to secure our role as healthcare providers of habilitation and rehabilitation using technologies as part of the plan of care. if technology is not integrated with o&p, clinical acceptance may be hindered. for example, computer-aided-design and manufacture (cad-cam) has been used in o&p for over 40 years,14 especially in prosthetics, yet the use of cad-cam in clinical orthotics practice is still relatively small compared to conventional fabrication of positive model creation, model rectification, thermoforming, lamination, and other processes. while we acknowledge that a generation of clinic owners/managers/and decision-makers may have missed formal education in cad cam methods, still there has been little pressure in o&p curricula to strengthen students' computer modelling skills beyond an introduction to industry specific software. challenges in sustaining orthotic and prosthetic education programs currently there are 13 master of science education programs accredited by the commission on accreditation of allied health education programs (caahep), based upon the recommendation of the committee on accreditation, the national commission on orthotic and prosthetic education (ncope).15 however, the track record of sustaining o&p clinical practitioner education programs at u.s. universities is rather poor. of the 22 clinical practitioner education programs developed since the 1960s, nine have been shuttered, representing a 41% closure rate. the dismal closure rate is alarming, and such vulnerability is particularly disconcerting given that knowledge and skills training are the core foundations of the profession. while there are a multitude of reasons for education program closures, the leading factors appear to be the loss of federal funding, the ongoing decline of state funding, high program operational costs, including extensive (and expensive) lab space and equipment requirements, and a dearth of qualified educators and researchers.16,17 moreover, o&p enrollments are among the smallest in a university, delivering little economic value derived from tuition and fees (e.g., georgia institute of technology, st. ambrose university, rutgers university, florida international university).17 how can the o&p profession advance and develop a cohesive, visionary, long term future with such a vulnerable funding model? the current o&p education curriculum needs to be re-examined if the profession is to address the challenges of limited budgets, substantial space and equipment requirements for labor-intensive fabrication and projected workforce demands. despite these barriers, four new education programs are planning to launch at universities across the u.s. in the next two years. these new programs have the opportunity to make the changes needed to ensure o&p programs remain viable in higher education, starting with curricular reform that reflects current and future o&p practice. in this case, greater emphasis should be devoted to areas in which today's o&p professionals have not had significant training, such as clinical diagnostics, identifying and prioritizing patient problems, treatment goal setting, formulation of treatment plan, dosage of o&p device use, prognosis, patient and caretaker communication and problem-solving skills. to counterbalance the increased emphasis on clinical knowledge and skill development, the technical component of the curriculum can be reduced by including new technologies that improve efficiency in fabrication processes, such as modular components that do not require custom fabrication. [we define technical fabrication as related to manufacture and production of devices, specifically thermoforming and lamination. alignment, fitting adjustments and device assembly would be included in clinical skills.] such changes are in line with contemporary practice analyses, devoting more time to preparing students for an imminent future of data-driven patient care, valuebased care and a wide array of efficient fabrication technologies. with a significant reduction of the technical fabrication aspects of the curriculum, programs could replace those areas of the curriculum with streamlined manufacturing processes as well as digitally augmented clinical decision-making (e.g., data science and artificial intelligence) and problem-solving. this approach has the potential to strengthen and solidify the clinical value of o&p practitioners. evidence-based practice is probably the single most important -and widely neglected -element for driving improvements in both clinical decision-making and o&p curriculum. expanding curriculum in this area, by including more coursework on searching, retrieving, evaluating, interpreting, and integrating new scientific knowledge will train students to utilize a systematic approach to patient care, using evidence to support their decision making and to quantify and characterize patient outcomes for valuesbased care. this approach reflects trends in evidencebased practice and values-based care that will likely continue into the future. the concept of interdisciplinary and interprofessional collaboration is another critical curriculum addition. due to the growing complexities of patient care and emerging technologies, it is no longer wise for clinicians to solve problems in a silo on their own;18 students must also learn these skills as part of their professional education. just as interprofessional health care teams can leverage their https://doi.org/10.33137/cpoj.v4i2.36673 4 kogler gf, hovorka cf. academia’s role to drive change in the orthotics and prosthetics profession. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.21. https://doi.org/10.33137/cpoj.v4i2.36673 issn: 2561-987x academia’s role to drive change kogler & hovorka., 2021 cpoj special s p e c ia l i s s u e collective intelligence for shared decision-making,19 engaging students from related programs (i.e., physical therapy, occupational therapy, engineering) in mock or actual patient case conferences can help shape their approach to patient-centered care19,20 and, help elevate the profile of o&p in the health care profession. universities that support the interprofessional education concept are on the rise21,22, and o&p programs will need to develop partnerships with multiple disciplines to capitalize on this emerging “value-added” curricular opportunity. an additional benefit of interprofessional education is that it encourages students to develop and practice good communication skills, a critical factor in understanding and communicating patient needs, priorities, and compliance, and for sharing knowledge and ideas among team members. communication skills were ranked as the highest priority for o&p employers hiring residents in the united states.23 in addition, communication skills were identified as an area of needed development for the future of o&p care across the globe.24 how do we advance data-driven decision-making? you do this by strengthening a student’s exposure to research in their clinical training. graduates who understand and interpret the medical, allied health science, movement science and engineering scientific literature in a systematic and clinically relevant way will be trained to apply their knowledge correctly and directly, leading to more informed successful patient assessment and treatment. these practitioners of the future will instinctively weave the scientific method into their daily practice, formulating testable questions for patients, devising data collection protocols, then analyzing, interpreting, and applying the data they collect. in turn, this process will yield the evidence that defines value of care and justifies clinical treatment decisions. professional and technological encroachment the increasing demand for o&p services, a projected shortage of providers, and market pressure for costeffective treatments are creating opportunities for other health professionals to fill the needs unmet by o&p today. moreover, technology-driven products and systems may yield an even greater challenge to the domain of o&p practice. patient-consumers are prone to see an orthosis or a prosthesis as a “device” to address their needs, and may not fully appreciate the added value of an expert clinician a contemporary orthotist and prosthetist should manage the patient, identify their needs, and match them with the technology/device that will best meet those needs as part of a therapeutic “body motion control” treatment plan. however, the consumer-direct marketing of orthoses and prostheses at reduced cost will likely be perceived as an attractive option for future o&p users, particularly in circumstances where healthcare disparity and barriers to access are an issue. for comparison, the profession of dentistry dealt with strikingly similar issues of professional encroachment over 40 years ago when the technical specialty of "denturists" successfully lobbied to provide dentures directly to patients, without a dentist and at significant cost savings.25,26 alternative access to dental services continues to evolve with a 20-plus year history of consumer-direct marketing of mail-order options for dentures and orthodontia (i.e., teeth aligners).27 consumers use home impression kits, photos, or scans for shape capture, which are then used to manufacture a person-specific fit of dentures or teeth aligners. the o&p profession is now experiencing the same trend, with consumer-direct prostheses and orthoses or print-your-own devices using a downloadable 3d file and 3d printer. currently, there is limited data available on the impact or efficacy that the consumer-direct movement will have on the o&p profession, and on habilitation and rehabilitation in general but we consider it a real, albeit emerging, challenge. such encroachments into o&p are likely to advance and will be difficult to curtail. however, with diversely skilled practitioners and strategic business acumen, the o&p profession can influence what aspect of the market to uphold and preserve by building the next novel businesses in o&p. academia can prepare future practitioners with the technical and business acumen to respond to the profession's service and market demands, addressing the entire spectrum of habilitation and rehabilitation in countries around the world. needs and priorities the o&p profession can only estimate the future healthcare economic determinants and market impacts, but it can nonetheless strategically position itself for change. because the demand of o&p services is expected to increase in tandem with a shortage of certified orthotists and prosthetists, more certified practitioners in o&p are needed. the principles of supply and demand cannot prevail without a stable environment for increasing the number of graduates entering the field; the expanded capabilities we suggest here, in clinical patient care and cost-effective manufacturing, can begin to curb the threat of other medical specialties competing for market share. but it is only with strategic curriculum changes that focus on strengthening skills in digital health technologies and evidence-based decision-making, that future o&p clinicians can confidently step into their role as "human interface experts” of wearables, exoskeletons and individualized assistive technologies. these reconceived practitioners will also be seen as valuable professional assets in interdisciplinary health care. https://doi.org/10.33137/cpoj.v4i2.36673 5 kogler gf, hovorka cf. academia’s role to drive change in the orthotics and prosthetics profession. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.21. https://doi.org/10.33137/cpoj.v4i2.36673 issn: 2561-987x academia’s role to drive change kogler & hovorka., 2021 cpoj special s p e c ia l i s s u e clearly academicians and university programs cannot change the profession on their own. they will need strong allies for leadership and support, through partnerships with industry, corporations, businesses, and professional organizations to forge the path for the future of the o&p profession. open, reflective partnerships with industry, corporations, and professional organizations will be critical to prepare the o&p profession for the future changes ahead. foundations in evidence-based practice using digital diagnostics, data science and artificial intelligence that augment clinical decision-making are the primary technological changes expected across the entire healthcare sector. therefore, our education programs must begin to strengthen the curriculum in these areas to create the new platform of skills and knowledge for practitioners. as a result, it is to be expected that clinical practice will change. therefore, expanding a practitioner’s skill set with three-dimensional computer modeling (3d cad) could be a strategic advantage for the profession. most allied health professionals do not possess 3d cad computer skills and such a skill set would distinguish the o&p profession. the current clinical mastery o&p practitioners are renowned for, producing negative impressions and positive model rectifications to create custom-molded devices, could be replaced or augmented with new competencies in computer-based scanning, 3d modelling and manufacturing processes and techniques. the o&p profession has an opportunity to be proactive by preparing for the health economic changes that will alter clinical practice as we know it. the current students entering o&p programs are digitally and technologically savvy and as such, possess the skillset for this type of future and the new students expect it will be the same way they will practice in o&p. the profession must ensure that our future practitioners are empowered to respond to the forthcoming economic changes healthcare will impress upon medicine, habilitation and rehabilitation. conclusions numerous healthcare economic factors are primed to provoke a major paradigm shift in the way o&p is practiced. curricular reform and innovation are therefore needed for o&p education programs to ensure that the next generation of o&p professionals are empowered to integrate emergent and novel technologies within the span of their professional careers. although machines can outsmart clinicians, they can’t out-kind, out-humor or out-finesse them. technology has a role in o&p, but only in the service of augmenting patient care. a critical aim is to ensure that an o&p professional’s knowledge is distinct from other healthcare professionals and is regarded as clinically valuable. to lessen professional encroachment, o&p professionals will need to adapt to change and work toward becoming the primary innovators, to guide maturation of the field, and seek to expand the domain of practice. o&p education programs will continue to be at risk for closure due to economic burdens they impose. strengthening clinical decision-making skills and decreasing the technical fabrication aspects of the curriculum will be important in moving toward a digital and technology-centric practice model while also making programs more sustainable and competitive in their respective universities. call to action a “visioning of the future o&p summit” will be essential for academicians and community stakeholders to evaluate the trends in healthcare and the skills and knowledge needed for the next generation of practitioners. the last o&p summit to debate the future and draft a strategic plan for action took place 16 years ago.16 orthotic and prosthetic communities of stakeholders should initially develop their own vision of the future, culminating in a comprehensive summit meeting whereby each community shares and debates their vision and followed by development of a strategic plan for the profession’s future and its place in rehabilitation. participating o&p communities would be represented as follows: • professional credentialing organizations (i.e., abc) – the upcoming practice analysis of o&p professionals will inform trends in practice. the last practice analysis was conducted in 2015. • o&p accreditation bodies (caahep and ncope) would be careful listeners, to not bias the debate on new core curriculum updates for o&p clinical practitioner training and education. • industry – practitioners and manufacturers will provide important perspectives to their needs and concerns. a visioning of the future o&p summit would serve as the culminating meeting to set the strategic educational plan for the future. the process is 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https://opedge.com/articles/viewarticle/2020-03-01/what-are-clinical-supervisors-looking-for-in-residents https://opedge.com/articles/viewarticle/2020-03-01/what-are-clinical-supervisors-looking-for-in-residents 7 kogler gf, hovorka cf. academia’s role to drive change in the orthotics and prosthetics profession. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.21. https://doi.org/10.33137/cpoj.v4i2.36673 issn: 2561-987x academia’s role to drive change kogler & hovorka., 2021 cpoj special s p e c ia l i s s u e authors scientific biography dr. géza f. kogler, is an associate professor and director of the master of science in prosthetics and orthotics program at kennesaw state university (ksu) in kennesaw, georgia. he received his doctorate in bioengineering from the university of strathclyde, glasgow scotland and a postgraduate certificate in orthotics from northwestern university prosthetics-orthotics center in chicago, il. he earned a baccalaureate degree in fine arts from wayne state university, detroit, mi. dr. kogler has been involved in orthotics and prosthetics education since 1986, serving as a faculty member at several universities (i.e., florida international university (usa), southern illinois university school of medicine (usa), jönköping university, (sweden), georgia institute of technology (usa), kennesaw state university (usa). he also is the principal investigator of the clinical biomechanics laboratory at ksu. his current research interests include powered exoskeletal systems for rehabilitation, sensing applications for diagnostics and musculoskeletal health, foot ankle biomechanics, and plantar foot tissue mechanics. dr. kogler has received numerous awards for his research in foot ankle biomechanics from the american society of biomechanics, the international society of biomechanics and the international society of prosthetics and orthotics. dr. christopher hovorka, completed bachelor’s degrees in exercise science (university of new mexico) and prosthetics and orthotics (university of washington), clinical residencies in orthotics (southern illinois university school of medicine) and prosthetics (connecticut children’s medical center, formerly newington children’s hospital), a master’s degree in allied health science (university of connecticut) and phd in applied physiology with focus in biomechanics and neuromotor control (georgia tech). he held faculty appointments at the university of texas southwestern medical center, st. ambrose university, georgia tech and the university of pittsburgh. he has received continuous research grant funding for over 20 years, in areas ranging from cognitive learning and curriculum development to the biomechanics and clinical outcomes of persons using lower limb prostheses, orthoses and footwear. he also developed the nation’s first accredited entry-level master’s degree in orthotics and prosthetics (o&p) at georgia tech. creation of that program sparked a national reassessment of the entry-level standards in o&p, and eventually adoption of the master’s degree as the entrylevel standard for o&p in the united states. currently, he is an assistant professor and director of a developing o&p program at etsu which will become the state of tennessee’s first entry-level master of science in o&p. https://doi.org/10.33137/cpoj.v4i2.36673 mcgrath m, davies kc, laszczak p, rek b, mccarthy j, zahedi s, moser d. the influence of hydraulic ankles and microprocessor-control on the biomechanics of trans-tibial amputees during quiet standing on a 5° slope. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.2. https://doi.org/10.33137/cpoj.v2i2.33517 issn: 2561-987x volume 2, issue 2 2019 (online) r e s e a r c h a r t i c l e all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). https://doi.org/10.33137/cpoj.v2i2.33517 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation 1 open access the influence of prosthetic ankles on the standing biomechanics of transtibial amputees volume 2, issue 2, article no.2, 2019 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index research article the influence of hydraulic ankles and microprocessor-control on the biomechanics of trans-tibial amputees during quiet standing on a 5° slope mcgrath m*, davies kc, laszczak p, rek b, mccarthy j, zahedi s, moser d blatchford group, unit d antura, bond close, basingstoke, rg24 8pz, uk. introduction musculoskeletal health problems are prevalent among lower limb amputees.1–4 the consensus among biomechanists is that the inherent asymmetry of the body, along with reduced confidence and proprioception on the prosthetic side, leads to an unequal distribution of limb loading between the two limbs.2,3,5 excessive dependence on the sound limb for support can have a degenerative effect on the joints. osteoarthritis (oa) is common, with studies reporting incidences in up to 41% of trans-tibial amputee4,5 (tta) community. most often, oa presents in the sound knee joint, affecting between 12-66% of all lower limb amputees,2,3,6 however up to 23% are also affected at the sound hip.2,3 there are also consequences for the residual side through reduced loading. osteoporosis (op) and osteopenia have been reported to affect the residual limbs of approximately 90% of people with lower limb amputation.3,4 one research study found a mean reduction in bone density of 15% across lower limb amputees, compared to the intact limb.2 another consequence of loading asymmetry is low back pain (lbp). the rate of occurrence has been reported to be as high as 48-71% in the lower limb amputee population1,3,7–9 as a whole and 62% for ttas,10 in particular. this figure is approximately double the estimated 28-30% of the general population that are affected by back pain.9,11 research has also highlighted how quickly this problem can develop, with 60% of amputees reporting moderate to extreme back pain occurring within the first two years after amputation.10 abstract background: lower limb amputees have a high incidence of comorbidities, such as osteoarthritis, which are believed to be caused by kinetic asymmetries. a lack of prosthetic adaptation to different terrains requires kinematic compensations, which may influence these asymmetries. method: six sigam grade e-f trans-tibial amputees (one bilateral) wore motion capture markers while standing on force plates, facing down a 5° slope. the participants were tested under three prosthetic conditions; a fixed attachment foot (fix), a hydraulic ankle (hyd) and a microprocessor foot with a ‘standing support’ mode (mpf). the resultant ground reaction force (grf) and support moment for prosthetic and sound limbs were chosen as outcome measures. these were compared between prosthetic conditions and to previously captured able-bodied control data. results: the distribution of grf between sound and prosthetic limbs was not significantly affected by foot type. however, the mpf condition required fewer kinematic compensations, leading to a reduction in sound side support moment of 59% (p=0.001) and prosthetic side support moment of 43% (p=0.02) compared to fix. for the bilateral participant, only the mpf positioned the grf vector anterior to the knees, reducing the demand on the residual joints to maintain posture. conclusion: for trans-tibial amputees, loading on lower limb joints is affected by prosthetic foot technology, due to the kinematic compensations required for slope adaptation. mpfs with ‘standing support’ might be considered reasonable and necessary for bilateral amputees, or amputees with stability problems due to the reduced biomechanical compensations evident. citation mcgrath m, davies kc, laszczak p, rek b, mccarthy j, zahedi s, moser d. the influence of hydraulic ankles and microprocessor-control on the biomechanics of trans-tibial amputees during quiet standing on a 5° slope. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.2. https://doi.org/10.33137/cpoj.v2i2.33 517 keywords prosthesis, transtibial amputees, gait analysis, kinematic, kinetic, amputation, microprocessor foot, hydraulic ankle, slope, symmetry, standing balance *corresponding author dr. michael mcgrath, research scientist–clinical evidence blatchford group, unit d antura, bond close, basingstoke, rg24 8pz, united kingdom email: mike.mcgrath@blatchford.co.uk orcid: https://orcid.org/0000-0003-0195-970x doi: https://doi.org/10.33137/cpoj.v2i2.33517 article info received: december 31, 2019 accepted: february 20, 2020 published: february 24, 2020 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v2i2.33517 https://doi.org/10.33137/cpoj.v2i2.33517 mailto:mike.mcgrath@blatchford.co.uk https://doi.org/10.33137/cpoj.v2i2.33517 mcgrath m, davies kc, laszczak p, rek b, mccarthy j, zahedi s, moser d. the influence of hydraulic ankles and microprocessor-control on the biomechanics of trans-tibial amputees during quiet standing on a 5° slope. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.2. https://doi.org/10.33137/cpoj.v2i2.33517 2 cpoj mcgrath et al. 2019 the influence of prosthetic ankles on the standing biomechanics of transtibial amputees the alignment of the lower limb prosthesis is one factor key to achieving a ‘close-to-normal’ posture and gait with even distribution of loads between prosthetic and sound limbs. the position and movement of the body’s centre-ofmass (com), relative to the positions of the lower limb joints, influences the forces and moments acting at those joints.12,13 this in turn affects the muscular effort required to provide support.14 typically, the alignment process within a clinic focuses on level ground ambulation. however, when walking or standing on uneven or sloped surfaces, the relative position of the body’s com to the lower limb joints changes and thus the alignment of a prosthesis may become sub-optimal.15–18 part of the problem may be the prosthetic device. in conventional, energy-storing-and-return (esr) feet that have a fixed attachment to the distal end of the prosthetic pylon, plantarflexion and dorsiflexion of the foot are achieved through deformation of the foot keel, which is often constructed of elastic elements and structures. if the foot cannot comply with sloped surfaces, compensatory movement of other joints may be required to ensure the foot is flat on the ground.19this is due to the reaction forces that are induced and act on the body as the keel deflects from a neutral unloaded condition. for unilateral ttas, this often presents as increased residual knee flexion.20,21this action puts the body’s com behind the knee joint centre, creating a flexion moment, which may require greater effort to resist. not only does this increase the day-to-day energy consumption of the user, but it also has negative implications on their stability and sound limb dependence. hydraulic ankles, which produce a viscoelastic response when loaded, allow a degree of damped movement proximal to the foot springs, ‘self-aligning’ with the ground and helping to maintain the body’s com position relative to the lower limb joints.19,22 this action minimises undesirable biased forces and moments acting on the limb, thus it may also reduce the compensations needed to enable effective standing on uneven surfaces.19 previous work has used the ground reaction force (grf) to determine the inter-limb load distribution during transfemoral amputee (tfa) standing tests.19 this approach, however, does not consider the loading at individual joints, which could provide greater insight into which joints are most at risk of oa development. furthermore, since possible compensation strategies may vary between amputees,19 winter’s concept of support moment23 may provide a more comprehensive and universal metric by which to measure the demand on a given limb to provide support. this is defined as the sum of the moments acting at the ankle, knee and hip, where extension moments make up the positive contribution to support and flexion moments provide a negative one.23 this study expands on the previous work19 to focus on ttas and, in particular, how differences in prosthetic foot and ankle technology can influence the way in which they stand on non-level ground. two hypotheses were tested. the first was that ttas would present with asymmetry in grf distribution when using a fixed attachment foot, which would be reduced when using adaptive feet. the second hypothesis was that the fixed attachment foot would lead to increased lower limb joint moments, compared to adaptive feet. methodology prosthetic devices three different prosthetic ankle/foot devices were evaluated in this study, each of which uses different prosthetic technology. the first was espriti (fix – blatchford, hampshire, uk), which is an esr foot with a fixed attachment to the distal end of the prosthetic pylon. the second device was echelonii (hyd – blatchford, hampshire, uk), which shares a common geometry with esprit but with a hydraulic ‘ankle’ unit attached proximally. plantarflexion and dorsiflexion of the foot are achieved through a combination of rotation of the hydraulic unit (allowing for 9° of damped movement) and the deformation of foot springs. the final device was elaniii (mpf – blatchford, hampshire, uk), with a hydraulic system similar to echelon, which includes microprocessorcontrol. the hydraulic unit provides damped ankle flexion adapting in real time to slopes and changes in speed but when the device detects that the user is standing still, the hydraulic resistances to movement in the plantarflexion and dorsiflexion directions are increased to a high level. this change is intended to provide both ground adaptation and extra support when standing. the high resistance is such that it permits small natural alignment adjustments but does not 'lock' the ankle in a fixed position, which may or may not be optimal. participants six tta participants volunteered for the study, the details of whom are listed in table 1. verbal participant information was given and signed consent was provided by each participant. an ethics review of the study followed the tenets of the declaration of helsinki and was approved by the institutional ethics review board. each person was aged 18 or over and, at the time of testing, their residual limbs were in good health, free from infection or skin conditions. a consultant prosthetist determined a sigam mobility grade e or higher for all participants, meaning they were capable of negotiating environmental barriers, such as sloped ground and ramps, with no other walking aids. each of the participants had experience using both fixed attachment and hydraulic ankle/foot devices. they had all initially been prescribed fixed attachment feet immediately post amputation and three (tt1, tt3 and tt4) still used this type of device as a running limb. at the time of testing, all participants had been using a hydraulic ankle or a microprocessor-controlled hydraulic ankle as their habitual, everyday device for at least 12 months. the data gathered during this study were compared to the same measurements gathered from a group of ablebodied control participants in a previous study19 (27.4±2.9 years, 66.8±10.3 kg). gait lab setup a motion capture system was used to track the movements of participants (codamotion, charnwood dynamics, leicestershire, uk). this system uses active marker clusters, two three-dimensional infra-red cameras and two force plates (kistler group, winterthur, switzerland) positioned side by side on a 5° slope. the cameras collected data at a frequency of 200hz, while the https://doi.org/10.33137/cpoj.v2i2.33517 mcgrath m, davies kc, laszczak p, rek b, mccarthy j, zahedi s, moser d. the influence of hydraulic ankles and microprocessor-control on the biomechanics of trans-tibial amputees during quiet standing on a 5° slope. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.2. https://doi.org/10.33137/cpoj.v2i2.33517 3 cpoj mcgrath et al. 2019 the influence of prosthetic ankles on the standing biomechanics of transtibial amputees force plate acquisition frequency was 500hz. body segment tracking and definitions of virtual markers were done using a conventional six-degree-of-freedom (6dof) marker model24 similar to that used in a previous study.19 the marker model was designed for able-bodied participants and required virtual markers at the medial and lateral malleoli. on the prosthetic limb, these were defined at the pivot point of the hydraulic units for the hyd and mpf devices. the similar geometry of the fix device meant that corresponding locations could be approximated when that device was worn.19 table 1: characteristics of the participants. please note echelonvt is a hydraulic ankle with an in-built vertical shock pylon/ torsion adaptor and echelonvac is a hydraulic ankle with an in-built mechanism for generating elevated vacuum suspension. s u b je c t g e n d e r s ig a m g ra d e a g e (y e a rs ) m a s s ( k g ) h e ig h t (m ) p ro s th e ti c lim b h a b it u a l p ro s th e s is tt1 male f 42 51 1.65 right echelonvt tt2 male f 24 60 1.70 right elan tt3 male f 38 92 1.83 right echelonvt tt4 male f 53 65 1.78 left echelonvac tt5 male f 45 92 1.77 right elan tt6 female e 36 55 1.75 both 2x elan data collection participants were asked to wear tight fitting shorts and t-shirts to permit the accurate positioning of markers, reduce marker occlusions and minimise movement artefact. each wore regular trainers and the same footwear was used for each prosthetic device tested. the testing protocol was based on that used in a previous study.19 participants stood facing down a 5° slope and, when instructed, stepped forwards, placing one foot on each of the two adjacent force plates. once on the force plates they were instructed to stand as naturally as possible. multiple trials (minimum of three) were used to measure at least 30 seconds of standing per participant. this meant that no single prosthetic device was detrimentally affected by initial foot positioning and steadying when a participant first stepped onto the force plates. each participant performed the testing protocol with each of the three prosthetic ankle/foot devices. each device was fitted and aligned by the same experienced senior prosthetist and the order in which they were tested was randomised. before data collection began with a new prosthetic device, the participants were given 30 minutes to acclimatise to the new foot. since each participant was already experienced with both fixed attachment and hydraulic prostheses, this time was deemed sufficient. regardless, testing would only proceed once both the participant and prosthetist were satisfied that they were capable of performing the protocol safely. data processing and analysis in order to ensure only quiet standing was analysed, the actions of stepping on and off of the force plates needed to be excluded. the final 3 seconds of each trial were rejected and the preceding 10 seconds were extracted and used in the final analysis. all kinetic parameters were normalised by the participant’s mass so that data were comparable between participants. all data were processed and analysed with visual3d v6 x64 biomechanics analysis software (c-motion inc., germantown, md, usa). statistical analysis the data were assessed for normality using shapiro-wilk tests and for homogeneity of variance using flignerkilleen tests. for normally distributed data, a one-way analysis of variance (anova) was used to identify statistically significant differences between the different prosthetic ankle/foot technologies and post-hoc tukey tests were performed for pairwise comparisons. for nonnormally distributed data, or for groups with heterogeneity of variances, kruskal-wallis tests were followed by posthoc dunn tests. statistical significance was defined as p<0.05. all statistical tests were performed using r v3.3.3 (the r foundation, vienna, austria). results kinematic compensations there were no significant differences between the mean joint angles for unilateral participants between prosthetic conditions. the bilateral amputee, however, did present with clear kinematic compensations (figure 1). the fix condition required knee flexion in order to achieve foot-flat. interestingly, for the hyd condition, knee flexion increased further (not significant) as the participant ‘rested’ on the mechanical dorsiflexion stops at the limit of the hydraulic range. the mpf condition allowed knee flexion to be reduced to a more upright posture (p=0.002 compared to fix). ta figure 1: the kinematic strategies of the bilateral trans-tibial amputee participant using (a) fix, (b) hyd and (c) mpf. kinetics (bodyweight distribution) there were no statistically significant differences in the resultant grf, or any of the three axial components, between the prosthetic conditions for the unilateral amputees. differences in the mean prosthetic and sound values were all less than 3%. the prosthetic condition did not significantly influence grf for the bilateral amputee either. https://doi.org/10.33137/cpoj.v2i2.33517 mcgrath m, davies kc, laszczak p, rek b, mccarthy j, zahedi s, moser d. the influence of hydraulic ankles and microprocessor-control on the biomechanics of trans-tibial amputees during quiet standing on a 5° slope. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.2. https://doi.org/10.33137/cpoj.v2i2.33517 4 cpoj mcgrath et al. 2019 the influence of prosthetic ankles on the standing biomechanics of transtibial amputees kinetics (joint moments) both prosthetic and sound support moments were significantly affected by prosthetic condition for the unilateral group (figure 2a). post hoc testing showed that, compared to fix (0.27 ± 0.19 nm/kg), both hyd (0.17 ± 0.12 nm/kg, p=0.038) and mpf (0.15 ± 0.12 nm/kg, p=0.020) reduced prosthetic side support moment. sound side support moment was also reduced by hyd (0.29 ± 0.17 nm/kg) compared to fix (0.41 ± 0.23 nm/kg, p=0.045). mpf reduced sound side support moment further (0.17 ± 0.16 nm/kg), which was statistically significant compared to fix (p=0.001) but not compared to hyd. these changes were mostly due to different ankle kinetics. the ankle moments for fix (0.25 ± 0.17 nm/kg prosthetic; 0.38 ± 0.25 nm/kg sound) were significantly decreased by hyd (0.16 ± 0.13 nm/kg prosthetic, p=0.009; 0.26 ± 0.19 nm/kg sound, p=0.034) and by mpf (0.18 ± 0.14 nm/kg prosthetic, p=0.042; 0.21 ± 0.19 nm/kg sound, p=0.004). another statistically significant change was the reduction of sound hip moment by mpf (0.02 ± 0.05 nm/kg) compared to fix (0.08 ± 0.03 nm/kg, p<0.001). when mpf was compared to hyd (0.06 ± 0.06 nm/kg), the reduction approached significance (p=0.06). for the bilateral amputee, support moment for hyd (0.62 ± 0.03 nm/kg) was significantly higher than both fix (0.46 ± 0.08 nm/kg, p=0.002) and mpf (0.28 ± 0.11 nm/kg, p<0.001). mpf significantly reduced knee moments (-0.08 ± 0.09 nm/kg) compared to both other conditions (fix: 0.08 ± 0.06 nm/kg, p=0.003, hyd: 0.078 ± 0.01 nm/kg, p=0.002). discussion the results of this study disproved the first hypothesis that ttas would present with grf distribution asymmetry when standing on a slope with a fixed attachment foot. however, the second hypothesis that the fixed attachment foot would increase joint moments, compared to adaptive feet, was found to be true. the observation that the ttas in this study did not display any obvious inter-limb grf asymmetry for any of the prosthetic technologies is in contrast to the findings of the previous research with tfas,19 suggesting that the participants had the confidence to load their prosthetic limb. this, in the long-term, may help to reduce the likelihood of op25 or lbp1 development. furthermore, again in contrast to the tfa participants,19 unilateral ttas did not present any significant differences in mean joint angles between prosthetic conditions. upon closer inspection, this observation could be attributed to the interparticipant variation and different strategies used to adapt their limbs to the gradient, some with knee flexion, some with hip flexion. this led to broad standard deviations, masking any trends. additionally, compared to tfas, it is possible that the extra control allowed by the residual knee joint meant that a foot-flat position could be achieved through greater foot spring deflection, with a reduced amount of knee flexion. these observations perhaps highlight the advantage of using the support moment metric for standing biomechanics and prosthetic alignment. the concept of support moment was devised by winter23 as a metric for use in gait analysis to show the bodyweight support provided by a limb as a whole. this research used the same method of calculation applied to quiet standing. the advantage of this approach is that it gives greater insight into the demand on the joints and how it is affected by changing test conditions, rather than only the weightbearing load. additionally, this metric is not sensitive to the compensation strategy used so it is not obscured by interparticipant variability. for the unilateral ttas, statistically significant changes were observed in both prosthetic and sound support moments. this shows that even though the participants were applying equal loads to their limbs, there was still an adverse effect on their sound side joints, which could be a risk factor in oa development.26,27 in the case of unilateral amputees, for example, the fix condition presented a significantly higher demand on the sound ankle (p=0.004) and hip (p<0.001), compared to mpf. consequently, the mpf presented the best scenario for the sound joints, as participants were able to align their joints to minimise the moments acting about them. figure 2: the relative contributions of ankle, knee and hip moment to the total support moment for (a) unilateral trans-tibial amputees, (b) a bilateral trans-tibial amputee and (c) able-bodied control participants. asterisks indicate statistical significance: *p<0.05, **p<0.01. obelisks indicate effect size changes: †|d|>0.5, ††|d|>0.8. https://doi.org/10.33137/cpoj.v2i2.33517 mcgrath m, davies kc, laszczak p, rek b, mccarthy j, zahedi s, moser d. the influence of hydraulic ankles and microprocessor-control on the biomechanics of trans-tibial amputees during quiet standing on a 5° slope. canadian prosthetics & orthotics journal. 2019;volume2, issue2, no.2. https://doi.org/10.33137/cpoj.v2i2.33517 5 cpoj mcgrath et al. 2019 the influence of prosthetic ankles on the standing biomechanics of transtibial amputees in a modelling analysis of quiet standing, winter highlighted that in the lower limbs, the ankle joint provided the greatest contribution to posture and balance.28 this was confirmed by the able-bodied control participants in this study where, of the individual joints, the greatest contribution to support was found at the ankle (figure 2c). this trend was also present in the sound limbs of the unilateral amputees, highlighting the potential benefits of a prosthetic technology that could reduce the demand on the ankle joint while maintaining a comfortable standing posture. these observations are what makes the bilateral tta participant such an interesting case study. the lack of any sound ankle – integral to maintaining posture28 – shifts the reliance to the knees or, indeed, the prosthetic technology. in this case, knee moments were affected by prosthetic condition. mpf was the only condition to produce negative knee moments. this indicated that the ground reaction vector had passed anterior to the knee joints. when prosthetists align devices in the clinic, this is one of their goals to achieve adequate balance with minimal muscular demand. the ability of a prosthetic ankle to adapt to changing gradients in this way is invaluable for a bilateral amputee, but extra prosthetic technology is required to compensate for the lack of a sound ankle. the hyd and mpf devices in this study have the same hydraulic range but, for the bilateral participant, increased knee flexion was only observed during the hyd condition. this was because the mpf devices provided “standing support”; initially adapting to the slope before increasing the resistance to ‘ankle’ movement when the sensors detected that the user was standing still. this held the mpf devices well-aligned, shifting the knee moment trend in-line with that observed for the able-bodied participants. other work has sought to compare different types of prosthetic feet when standing on slopes, but the gradients used were higher than that in the current study (7° slope,20 10° slope21 and 15° slope,29 respectively) so direct, quantifiable comparisons are challenging. however, similar trends were reported for the comparison of fixed attachment feet to feet with adaptive ankles. reduced residual knee flexion was observed when using the adaptive feet, compared to fixed,20,21 affecting joint moments. ernst et al.21 also noted the different strategies employed by participants to adapt to the slope and how this influences the variability of the measurements. it is worth acknowledging that the protocol of this study might have influenced the findings to some degree. software limitations meant that recordings could only be performed for relatively short intervals. future work might ask participants to stand for longer time periods, recording short intervals throughout that longer period. this would highlight whether differences between prosthetic conditions become more substantial as the participants become more fatigued. conclusion this study has shown that unilateral ttas are able to maintain approximate weight-bearing symmetry between their prosthetic and sound limbs while standing on sloped ground. however, the demand that is placed on their joints is dependent upon the ease in which they are able to maintain an upright posture. hydraulic ankles allow selfalignment, resulting in fewer kinematic compensations and reducing the moments on the sound joints. for bilateral ttas, the combination of ankle adaptation and standing support provided by the mpf, represented the only condition under which the ground reaction vector was anterior to the knee joints. this suggests that mpf technology is particularly important for bilateral amputees, in order to protect the joints against excessive demand and the development of oa. acknowledgements the authors wish to thank the participants for taking the time to volunteer for this study. declaration of conflicting interests the authors are full time employees of the manufacturer of the prosthetic devices examined in this study. ethical approval an ethics review of the study followed the tenets of the declaration of helsinki and was approved by the institutional ethics review board. author contribution • michael mcgrath, conceptualization, data collection, data analysis, manuscript preparation, review and editing. • katherine c. davies, manuscript preparation, review and editing. • piotr laszczak, data analysis, manuscript review and editing. • beata rek, data analysis, manuscript review and editing. • joe mccarthy, conceptualization, data collection, manuscript review and editing. • saeed zahedi, conceptualization, manuscript review and editing. • david moser, conceptualization, manuscript review and editing. sources of support blatchford provided financial support and prosthetic devices for this study. references 1. ehde dm, smith dg, czerniecki jm, campbell km, malchow dm, robinson lr. back pain as a secondary disability in persons with lower limb amputations. arch phys med rehabil. 2001; 82: 731–734. https://doi.org/10.1053/apmr.2001.21962 2. kulkarni j, adams j, thomas e, silman a. association between amputation, arthritis and osteopenia in british male war veterans with major 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amputees: results of a national survey. arch phys med rehabil.2005; 86: 1910–1919. https://doi.org/10.1016/j.apmr.2005.03.031 10. kulkarni j, gaine wj, buckley jg, rankine jj, adams j. chronic low back pain in traumatic lower limb amputees. clin rehabil. 2005; 19: 81–86. https://doi.org/10.1191/0269215505cr819oa 11.kulkarni j. post amputation syndrome. prosthet orthot int. 2008; 32: 434–437. https://doi.org/10.1080/03093640802258637 12. blumentrttt s. a new biomechanical method for determination of static prosthetic alignment. prosthet orthot int. 1997; 21: 107– 113. 13. blumentrttt s, sghmalz t, jarasch r, schneider m. effects of sagittal plane prosthetic alignment on standing trans-tibial amputee knee loads. prosthet orthot int. 1999; 23: 231–238. 14.houdijk h, fickert r, van velzen j, van bennekom c. the energy cost for balance control during upright standing. gait posture. 2009; 30:150–154. https://doi.org/10.1016/j.gaitpost.2009.05.009 15. vrieling ah, van keeken hg, schoppen t, otten e, halbertsma jpk, hof al, et al. uphill and downhill walking in unilateral lower limb amputees. gait posture. 2008; 28: 235–242. https://doi.org/10.1016/j.gaitpost.2007.12.006 16. vickers dr, palk c, mcintosh as, beatty kt. elderly unilateral transtibial amputee gait on an inclined walkway: a biomechanical analysis. gait posture. 2008; 27: 518–529. https://doi.org/10.1016/j.gaitpost.2007.06.008 17. bai x, ewins d, crocombe ad, xu w. kinematic and biomimetic assessment of a hydraulic ankle/foot in level ground and camber walking. plos one 2017; 12: e0180836. doi: 10.1371/journal.pone.0180836 18. wirta rw, mason r, calvo k, golbranson fl. effect on gait using various prosthetic ankle-foot devices. j rehabil res dev 1991; 28: 13–24. 19. mcgrath m, laszczak p, zahedi s, moser d. microprocessor knees with “standing support” and articulating, hydraulic ankles improve balance control and inter-limb loading during quiet standing. j rehabil assist technol eng. 2018; 5: 2055668318795396. https://doi.org/10.1177/2055668318795396 20. thomas-pohl m, villa c, davot j, bonnet x, facione j, lapeyre e, bascou j, pillet h. microprocessor prosthetic ankles: comparative biomechanical evaluation of people with transtibial traumatic amputation during standing on level ground and slope. disabil rehabil assist technol. 2019; 1–10. https://doi.org/10.1177/2055668318795396 21.ernst m, altenburg b, bellmann m, schmalz t. standing on slopes – how current microprocessor-controlled prosthetic feet support transtibial and transfemoral amputees in an everyday task. j neuroeng rehabil. 2017; 14: 117. doi: 10.1186/s12984-017-0322-2. 22.de asha ar, johnson l, munjal r, kulkarni j, buckley jg. attenuation of centre-of-pressure trajectory fluctuations under the prosthetic foot when using an articulating hydraulic ankle attachment compared to fixed attachment. clin biomech. 2013; 28: 218–224. https://doi.org/10.1016/j.clinbiomech.2012.11.013 23. winter da. kinematic and kinetic patterns in human gait: variability and compensating effects. hum movement sci.1984; 3: 51–76. 24. charnwood dynamics ltd. odin feature guides. codamotion wiki, https://codamotion.com/wiki/product-guides/odin-featureguides/ (2019). 25. sherk vd, bemben mg, bemben da. bmd and bone geometry in transtibial and transfemoral amputees. j bone miner res. 2008; 23: 1449–1457. https://doi.org/10.1359/jbmr.080402 26. royer td, wasilewski ca. hip and knee frontal plane moments in persons with unilateral, trans-tibial amputation. gait posture. 2006; 23: 303–306. https://doi.org/10.1016/j.gaitpost.2005.04.003 27. lemaire ed, fisher fr. osteoarthritis and elderly amputee gait. arch phys med rehabil.1994; 75: 1094–1099. https://doi.org/10.1016/0003-9993(94)90084-1 28. winter da, patla ae, prince f, ishac m, gielo-perczak k. stiffness control of balance in quiet standing. j neurophysiol. 1998; 80: 1211–1221. https://doi.org/10.1152/jn.1998.80.3.1211 29.kaluf b, duncan a, bridges w. comparative effectiveness of microprocessor-controlled and carbon-fiber energy-storingand-returning prosthetic feet in persons with unilateral transtibial amputation: patient-reported outcome measures. j prosthet orthot. 2020: online ahead of print. doi: 10.1097/jpo.0000000000000288 manufacturers’ documentation i http://www.blatchfordus.com/products/esprit ii http://www.blatchfordus.com/products/echelon iii http://www.blatchfordus.com/products/elan https://doi.org/10.33137/cpoj.v2i2.33517 http://dx.doi.org/10.1136/ard.37.3.252 https://doi.org/10.1016/j.apmr.2004.04.034 https://doi.org/10.1053/apmr.2000.7583 https://doi.org/10.1016/j.apmr.2005.03.031 https://doi.org/10.1191/0269215505cr819oa https://doi.org/10.1080/03093640802258637 https://doi.org/10.1016/j.gaitpost.2009.05.009 https://doi.org/10.1016/j.gaitpost.2007.12.006 https://doi.org/10.1016/j.gaitpost.2007.06.008 https://doi.org/10.1177/2055668318795396 https://doi.org/10.1177/2055668318795396 https://doi.org/10.1016/j.clinbiomech.2012.11.013 https://doi.org/10.1359/jbmr.080402 https://doi.org/10.1016/j.gaitpost.2005.04.003 https://doi.org/10.1016/0003-9993(94)90084-1 https://doi.org/10.1152/jn.1998.80.3.1211 http://www.blatchfordus.com/products/esprit http://www.blatchfordus.com/products/echelon http://www.blatchfordus.com/products/elan all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 1 2020 research article marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1. https://doi.org/10.33137/cpoj.v3i1.33916 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://doi.org/10.33137/cpoj.v3i1.33916 1 marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1.https://doi.org/10.33137/cpoj.v3i1.33916 research article comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation marquez m.g1, kowgier m2, journeay w.s3,4,* 1 department of anatomy and cell biology, mcgill university, montreal, canada. 2 dalla lana school of public health, university of toronto, toronto, canada. 3 providence healthcare – unity health toronto, toronto, on, canada. 4 division of physical medicine and rehabilitation, department of medicine, university of toronto, toronto, canada. introduction the primary risk factors for lower extremity amputation (lea) are diabetes and peripheral arterial disease along with associated dysvascular complications.1-4 when combined, peripheral arterial disease and diabetes are associated with greater than 80% of lea in canada 4,5 and recent population-based research by hussain et al.,6 demonstrated that diabetes-related amputations are on the rise. moreover, patients with dysvascular limb loss often carry a burden of comorbidity including cognitive impairment and heart failure among others which can potentially further impact recovery and function in hospitalized patients after amputation.7,8 after a lea, patients may be discharged to inpatient rehabilitation, specialized nursing facilities, or directly home, open access volume 3, issue 1, article no.1. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: dysvascular amputations arising from peripheral vascular disease and/or diabetes are common. patients who undergo amputation often have additional comorbidities that may impact their recovery after surgery. many individuals undergo post-operative inpatient rehabilitation to improve their non-prosthetic functional independence. thus far, our characterization of comorbidity in this population and how it is associated with non-prosthetic inpatient functional recovery remains relatively unexplored. objective: the objective of this study was to describe comorbidities, using the charlson comorbidity index (cci), and to examine associations between comorbidity and functional outcomes in a cohort of patients with dysvascular limb loss undergoing non-prosthetic inpatient rehabilitation. methodology: a retrospective cohort design was used to analyze a group of 143 patients with unilateral, dysvascular limb loss who were admitted to inpatient rehabilitation. age, sex, amputation level, amputation side, length of stay (los), time since surgery, functional independence measure (fim) scores (total and motor at admission and discharge), and cci scores were collected. findings: the data showed that neither total or specific comorbidities were associated with functional outcomes or los in this cohort and rehabilitation model. multivariate analysis demonstrated an inverse relationship with age and fim scores, where increased age was associated with lower total and motor fim at admission and discharge. comorbidities were not associated with functional outcomes. dementia was negatively associated with fim scores, however this requires more study given the low number of patients with dementia in this cohort. conclusion: these data suggest that regardless of burden of comorbidity or specific comorbidities that patients with dysvascular limb loss may derive similar functional benefit from post-operative nonprosthetic inpatient rehabilitation. article info received: march 29, 2020 accepted: may 8, 2020 published: may 16, 2020 citation marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1. https://doi.org/10.33137/cpoj. v3i1.33916 keywords amputation, comorbidity, dysvascular, inpatient rehabilitation, charlson comorbidity index, functional independence measure, diabetes, limb loss, rehabilitation, amputee. * corresponding author: dr. w. shane journeay, phd, md, mph, frcpc, bc-occ med providence healthcare – unity health toronto, 3276 st clair avenue east, toronto on m1l 1w1 e-mail: shane.journeay@utoronto.ca orcid: https://orcid.org/0000-0001-6075-3176 https://doi.org/10.33137/cpoj.v3i1.33916 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i1.33916 https://doi.org/10.33137/cpoj.v3i1.33916 https://orcid.org/0000-0001-6075-3176 2 marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1.https://doi.org/10.33137/cpoj.v3i1.33916 issn: 2561-987x comorbidity and inpatient rehabilitation after amputation marquez et al. 2020 cpoj with the destination contingent on factors such as the patient’s age, level of amputation, and family support9-12 as well as the location and availability of rehabilitation facilities. inpatient rehabilitation is particularly beneficial as it correlates to fewer additional amputations, reduced mortality, a greater probability of receiving a prosthesis, and improved medical stability.10,13 regardless of one’s prosthetic candidacy, patients undergoing amputation have a number of post-operative rehabilitation needs including transfer training, wheelchair skills and contracture prevention. a patient’s stay in inpatient rehabilitation and medical status after surgery may be impacted not only by the amputation, but also by other comorbidities they may have.12 to date, few studies have examined comorbidity in patients with dysvascular limb loss and/ its association with functional outcomes and length of stay in the non-prosthetic inpatient rehabilitation setting. a measure that can be used to quantify comorbidity is the charlson comorbidity index (cci).14,15 in the classical chart review version of the cci, it is split into individual conditions, each assigned a weighted score of either 1, 2, 3, or 6. a higher total score indicates a greater burden of comorbidities and a higher risk of mortality in hospitalized patients. the functional independence measure (fim) is a standardized indicator of functional progress in the inpatient rehabilitation setting and such data can be readily obtained from rehabilitation hospital data reporting systems.16,17 given its common use in inpatient rehabilitation settings, the fim can be used as a clinical marker to reflect progression in self care, transfers and wheelchair independence needed before non-prosthetic discharge. the majority of prior studies have catalogued common comorbidities without using an established index or they employed various measures of functional outcome outside of the inpatient non-prosthetic setting. for example, melchiorre et al.8 have investigated the relationship between comorbidities and rehabilitation for patients with lea. however, their work focused on amputations of etiology that were both traumatic and vascular. they used a modified cci in order to reflect their study sample, and looked at correlations with length of stay (los) and fim scores. chopra et al.18 also studied the relationship between comorbidities and functional outcomes in patients with lower extremity amputation. their study did not focus on inpatient rehabilitation, as most of their cohort were discharged to skilled nursing facilities. they measured function by observing patient independence with activities of daily living (adl) and ambulation. they did not use the cci, but tallied several specific comorbidities. vogel et al.,7 looked at the impact of amputation and comorbidities using the cci in nursing home residents with lea. due to the elderly cohort and their disposition in a nursing home, the treatment provided was more residential rather than focused predominantly on post-operative, non-prosthetic rehabilitation. they also measured function with performance of adls. cheng et al. found no association of comorbidity with unplanned discharge or functional gains however they utilized specific medical predictors rather than an index such as the cci.19 the role of comorbidity is increasingly an important area of study as even in patients with dyvascular limb loss under the age of 65 years old there exists a high burden of comorbidity.20 while there has been previous work concerning the role of comorbidity on prosthetic rehabilitation outcomes, there has not been a more comprehensive look into the distinct components of the cci and its association with inpatient non-prosthetic rehabilitation outcomes including the fim and los. thus, with increasing rates of amputation related to diabetes6 and a greater number of patients needing rehabilitation,12 this remains a relevant topic to explore. therefore, the purpose of this study was to describe comorbidities, using the cci, and to examine associations between comorbidity, functional outcomes and los in a cohort of patients with dysvascular lower limb loss undergoing non-prosthetic inpatient rehabilitation. methodology this was a retrospective cohort study and was approved by the research ethics board of providence healthcare and closed by the unity health toronto research ethics board. all patients with a lea that were discharged from our rehabilitation hospital between january 1, 2014 and march 30, 2018 were identified and their medical records were reviewed. inclusion criteria for the study consisted of those with a recent unilateral, transfemoral (tf) or transtibial (tt) amputation. only those amputations with a dysvascular or diabetic cause were included, and those due to trauma, cancer or other reasons were excluded. those receiving hemodialysis were also excluded from this study as data from this group was used in a separate comparative study. inclusion and exclusion criteria were developed to establish a uniform data set of the most common reason for admission to post-amputation rehabilitation (dyvascular amputation). patients who met inclusion criteria but had an incomplete data set were excluded. all data retrieved from medical records came from both physical charts and electronic files utilized by health information management at the hospital. the rehabilitation model at this institution involved post-operative interdisciplinary rehabilitation including physiotherapy, occupational therapy, nursing, wound care and physiatry consultation. the focus of rehabilitation for these patients was non-prosthetic rehabilitation only which includes but is not limited to; wound care, standing tolerance, contracture prevention, transfers and wheelchair skills. patients were discharged home after non-prosthetic rehabilitation and then revisited regarding prosthetic candidacy and gait training at a later date. data that was extracted from the medical records included age, sex, amputation level, https://doi.org/10.33137/cpoj.v3i1.33916 3 marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1.https://doi.org/10.33137/cpoj.v3i1.33916 issn: 2561-987x comorbidity and inpatient rehabilitation after amputation marquez et al. 2020 cpoj amputation side, surgery date, los in inpatient rehabilitation, fim scores at admission and discharge,16,17 and cci scores.14,15 the authors are aware that the cci was initially used as an epidemiological tool to predict mortality in patients admitted to hospital. however, we have selected it as a standardized method in which to catalogue comorbidities. each patient was reviewed using the cci and assigned points for the individual conditions, then given a total score. these scores were based on information present upon their admission and any past medical history that was documented in the chart. the time since surgery was also recorded by calculating the number of days between the surgery date and the admission date to inpatient rehabilitation. los in rehabilitation was calculated from admission date to discharge date. total fim, and total motor fim information was retrieved from admission and discharge data. we included motor fim because in the nonprosthetic phase of rehabilitation, the motor fim scores would reflect acquisition of independence with transfers and wheelchair mobility as this study did not examine prosthetic gait outcomes. statistical methods continuous variables were summarized by observed means with standard deviation (sd) and categorical variables were summarized by frequency counts (percentages). univariate and multivariate linear regression analyses were used to investigate the effect of comorbidities on each of the outcomes of total and motor fim at both admission and discharge as well as los. multiple regression analysis adjusted for clinically relevant variables including age and sex as well as any comorbidities showing statistical association (p < 0.05) in univariate analysis. data was analyzed using the r statistical software (version 3.5.1). results all patients admitted with a diagnosis of lea from january 1, 2014 to march 30, 2018 were identified by our medical records team for a total of 382 charts. three patients were excluded due to death prior to discharge. four patients were excluded due to incomplete admission to discharge data sets. twenty-five patients were excluded due to hemodialysis. two hundred and seven charts were excluded by not meeting inclusion criteria such as: etiology of amputation (i.e. not dysvascular), had bilateral amputations, or were not tt or tf level amputations (i.e. only forefoot or toe amputation), or were not admitted postoperatively but rather for other reasons such as gait training or other medical conditions. there was a total of 143 patients who met inclusion criteria and were analyzed (table 1). the majority of the cohort was male (66%) and the mean age was 68 years old. most of the cohort had a tt level amputation (59%). ninety-five percent of the cohort had peripheral vascular disease (pvd), 68% had diabetes mellitus (dm), 87% had hypertension (hbp), and 42% had a skin ulcer. table 1 presents further descriptive data, along with the distribution of the rest of the individual comorbidity scores. table 1: cohort characteristics and charlson comorbidity index. cohort n = 143 (%) age (years) 67.7 (sd 11.1) sex m 95 (66) f 48 (34) amputation level transfemoral 59 (41) transtibial 84 (59) amputation side left 69 (48) right 74 (52) length of stay in rehabilitation (los) 33.9 (sd 18.6) time since surgery to admission (days) 15.2 (sd 13.8) fim scores overall total admission 72.6 (sd 14.4) overall total discharge 97.5 (sd 14.3) motor total admission 42.7 (sd 12.0) motor total discharge 66.9 (sd 11.4) efficiency 0.9 (sd 0.5) charlson total 4.7 (sd 1.7) charlson comorbidity index items peripheral vascular disease 136 (95) high blood pressure 124 (87) diabetes mellitus 78 (55) skin ulcer 60 (42) chronic obstructive pulmonary disease 31 (22) myocardial infarction 27 (19) cerebrovascular accident 19 (13) diabetes mellitus end organ 19 (13) congestive heart failure 16 (11) depression 13 (9) cancer / malignancy 9 (6) warfarin 9 (6) peptic ulcer disease 6 (4) dementia 6 (4) rheumatic disease 4 (3) renal disease 3 (2) mild liver disease 1 (1) mod-sev liver disease 2 (1) metastatic cancer 1 (1) human immunodeficiency virus 0 (0) hemiplegia 0 (0) https://doi.org/10.33137/cpoj.v3i1.33916 4 marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1.https://doi.org/10.33137/cpoj.v3i1.33916 issn: 2561-987x comorbidity and inpatient rehabilitation after amputation marquez et al. 2020 cpoj f im t o ta l a d m is s io n f im t o ta l d is c h a rg e f im m o to r a d m is s io n f im m o to r d is c h a rg e l e n g th o f s ta y ( l o s ) b e ta c i p v a lu e b e ta c i p v a lu e b e ta c i p v a lu e b e ta c i p v a lu e b e ta c i p v a lu e s e x ( f e m a le v s m a le ) -3 .5 1 [( -8 .4 9 ) (1 .4 7 )] 0 .1 7 0 -3 .0 6 [( -8 .0 1 ) (1 .9 0 )] 0 .2 2 9 -4 .3 6 [( -8 .4 6 ) (0 .2 5 )] 0 .0 4 0 * -3 .8 6 [( -7 .7 7 ) (0 .0 5 )] 0 .0 5 5 -1 .0 4 [( -7 .5 3 ) (5 .4 4 )] 0 .7 5 3 a m p s id e ( l e ft v s r ig h t) -1 .4 7 [( -6 .2 0 ) (3 .2 7 )] 0 .5 4 5 -1 .8 9 [( -6 .5 8 ) (2 .8 1 )] 0 .4 3 3 -0 .1 3 [( -4 .0 7 ) (3 .8 1 )] 0 .9 4 8 -1 .2 5 [( -4 .9 9 ) (2 .4 9 )] 0 .5 1 3 3 .6 0 [( -2 .5 0 ) (9 .7 0 )] 0 .2 4 9 a m p l e v e l ( t f v s t t ) -3 .0 6 [( -7 .8 4 ) (1 .7 3 )] 0 .2 1 3 -1 .9 2 [( -6 .6 9 ) (2 .8 5 )] 0 .4 3 1 -3 .0 5 [( -7 .0 2 ) (0 .9 2 )] 0 .1 3 4 -2 .7 8 [( -6 .5 5 ) (0 .9 9 )] 0 .1 5 1 -2 .1 9 [( -8 .3 9 ) (4 .0 2 )] 0 .4 9 1 a g e -0 .5 8 [( -0 .7 8 ) (0 .3 9 )] 0 * -0 .4 7 [( -0 .6 7 ) (0 .2 8 )] 0 * -0 .4 5 [( -0 .6 1 ) (0 .2 9 )] 0 * -0 .3 3 [( -0 .4 9 ) (0 .1 7 )] 0 * 0 .2 4 [( -0 .0 4 ) (0 .5 1 )] 0 .0 9 2 c h a rl s o n t o ta l s c o re -1 .2 8 [( -2 .6 6 ) (0 .0 9 )] 0 .0 7 0 -1 .0 8 [( -2 .4 5 ) (0 .3 0 )] 0 .1 2 6 -1 .1 3 [( -2 .2 8 ) (0 .0 1 )] 0 .0 5 4 -0 .9 3 [( -2 .0 2 ) (0 .1 6 )] 0 .0 9 6 0 .7 6 [( -1 .0 4 ) (2 .5 6 )] 0 .4 1 0 c h a rl s o n ( > = 6 v s < 6 ) -3 .6 4 [( -8 .8 1 ) (1 .5 3 )] 0 .1 6 9 -2 .7 2 [( -7 .8 7 ) (2 .4 3 )] 0 .3 0 2 -3 .8 0 [( -8 .0 8 ) (0 .4 8 )] 0 .0 8 4 -3 .1 1 [( -7 .1 9 ) (0 .9 6 )] 0 .1 3 6 0 .3 3 [( -6 .3 9 ) (7 .0 6 )] 0 .9 2 3 charlson items m y o c a rd ia l in fa rc ti o n 0 .5 8 [( -5 .4 8 ) (6 .6 3 )] 0 .8 5 2 1 .9 3 [( -4 .0 7 ) (7 .9 4 )] 0 .5 2 9 -0 .0 9 [( -5 .1 3 ) (4 .9 4 )] 0 .9 7 1 1 .2 2 [( -3 .5 5 ) (5 .9 9 )] 0 .6 1 8 -0 .1 9 [( -8 .0 2 ) (7 .6 3 )] 0 .9 6 2 c o n g e s ti v e h e a rt f a ilu re -2 .9 8 [( -1 0 .4 8 ) (4 .5 2 )] 0 .4 3 8 -1 .9 4 [( -9 .3 9 ) (5 .5 2 )] 0 .6 1 2 -4 .7 4 [( -1 0 .9 3 ) (1 .4 6 )] 0 .1 3 6 -3 .8 7 [( -9 .7 7 ) (2 .0 3 )] 0 .2 0 1 5 .2 2 [( -4 .4 5 ) (1 4 .9 0 )] 0 .2 9 2 p e ri p h e ra l v a s c u la r d is e a s e -3 .5 3 [( -1 4 .4 9 ) (7 .4 4 )] 0 .5 2 9 -4 .1 6 [( -1 5 .0 5 ) (6 .7 2 )] 0 .4 5 4 0 .4 4 [( -8 .6 8 ) (9 .5 7 )] 0 .9 2 4 -0 .6 7 [( -9 .3 3 ) (8 .0 0 )] 0 .8 8 0 3 .0 1 [( -1 1 .1 7 ) (1 7 .1 9 )] 0 .6 7 8 c e re b ro v a s c u la r a c c id e n t -8 .0 9 [( -1 4 .9 4 ) (1 .2 4 )] 0 .0 2 2 * -7 .8 2 [( -1 4 .6 3 ) (1 .0 1 )] 0 .0 2 6 * -5 .2 5 [( -1 0 .9 8 ) (0 .4 9 )] 0 .0 7 5 -4 .6 6 [( -1 0 .1 2 ) (0 .7 9 )] 0 .0 9 6 5 .0 8 [( -3 .9 0 ) (1 4 .0 6 )] 0 .2 7 0 c o p d 0 .0 8 [( -5 .6 6 ) (5 .8 3 )] 0 .9 7 7 2 .3 7 [( -3 .3 3 ) (8 .0 6 )] 0 .4 1 7 -1 .3 1 [( -6 .0 9 ) (3 .4 6 )] 0 .5 9 1 1 .2 7 [( -3 .2 6 ) (5 .8 1 )] 0 .5 8 2 3 .3 1 [( -4 .1 0 ) (1 0 .7 2 )] 0 .3 8 3 d ia b e te s e n d o rg a n 3 .3 2 [( -3 .6 3 ) (1 0 .2 8 )] 0 .3 5 1 -0 .2 4 [( -7 .1 7 ) (6 .6 9 )] 0 .9 4 7 1 .9 8 [( -3 .8 2 ) (7 .7 7 )] 0 .5 0 5 -0 .7 8 [( -6 .2 8 ) (4 .7 3 )] 0 .7 8 3 1 .1 9 [( -7 .8 3 ) (1 0 .2 1 )] 0 .7 9 6 s k in u lc e r -3 .8 0 [( -1 5 .6 0 ) (8 .0 0 )] 0 .5 2 9 1 .0 8 [( -1 0 .6 6 ) (1 2 .8 1 )] 0 .8 5 8 -6 .1 3 [( -1 5 .9 0 ) (3 .6 4 )] 0 .2 2 1 -0 .4 6 [( -9 .7 8 ) (8 .8 7 )] 0 .9 2 4 5 .1 9 [( -1 0 .0 6 ) (2 0 .4 4 )] 0 .5 0 6 m e ta s ta ti c c a n c e r -0 .3 3 [( -1 0 .0 9 ) (9 .4 2 )] 0 .9 4 7 4 .4 8 [( -5 .1 8 ) (1 4 .1 4 )] 0 .3 6 5 0 .9 1 [( -7 .2 0 ) (9 .0 1 )] 0 .8 2 7 3 .6 2 [( -4 .0 5 ) (1 1 .3 0 )] 0 .3 5 6 -1 .7 5 [( -1 4 .3 5 ) (1 0 .8 6 )] 0 .7 8 6 d e m e n ti a -2 3 .4 6 [( -3 4 .6 3 ) (1 2 .3 0 )] 0 * -2 8 .8 5 [( -3 9 .5 7 ) (1 8 .1 2 )] 0 * -1 6 .3 9 [( -2 5 .8 4 ) (6 .9 5 )] 0 .0 0 1 * -1 9 .4 2 [( -2 8 .1 8 ) (1 0 .6 6 )] 0 * -3 .5 1 [( -1 8 .7 7 ) (1 1 .7 5 )] 0 .6 5 3 r h e u m a ti c d is e a s -5 .0 3 [( -1 9 .3 8 ) (9 .3 1 )] 0 .4 9 3 2 .3 5 [( -1 1 .9 1 ) (1 6 .6 1 )] 0 .7 4 8 -8 .4 4 [( -2 0 .3 0 ) (3 .4 2 )] 0 .1 6 5 -1 .2 2 [( -1 2 .5 6 ) (1 0 .1 2 )] 0 .8 3 3 5 .5 4 [( -1 3 .0 0 ) (2 4 .0 9 )] 0 .5 5 9 h ig h b lo o d p re s s s u re -9 .4 6 [( -1 6 .2 6 ) (2 .6 5 )] 0 .0 0 7 * -7 .7 8 [( -1 4 .5 9 ) (0 .9 6 )] 0 .0 2 7 * -6 .4 1 [( -1 2 .1 1 ) (0 .7 0 )] 0 .0 2 9 * -4 .0 8 [( -9 .5 5 ) (1 .3 9 )] 0 .1 4 6 8 .4 0 [( -0 .5 2 ) (1 7 .3 1 )] 0 .0 6 7 s k in u lc e r -3 .0 6 [( -7 .8 4 ) (1 .7 1 )] 0 .2 1 1 -2 .6 4 [( -7 .3 9 ) (2 .1 0 )] 0 .2 7 7 -3 .2 6 [( -7 .2 1 ) (0 .7 0 )] 0 .1 0 9 -2 .8 8 [( -6 .6 4 ) (0 .8 8 )] 0 .1 3 6 2 .7 4 [( -3 .4 5 ) (8 .9 3 )] 0 .3 8 7 d e p re s s io n 1 .6 6 [( -6 .5 8 ) (9 .9 0 )] 0 .6 9 3 3 .5 5 [( -4 .6 2 ) (1 1 .7 1 )] 0 .3 9 6 0 .5 8 [( -6 .2 7 ) (7 .4 3 )] 0 .8 6 9 2 .1 0 [( -4 .4 0 ) (8 .6 0 )] 0 .5 2 7 -1 .9 6 [( -1 2 .6 1 ) (8 .6 8 )] 0 .7 1 9 w a rf a ri n -0 .9 2 [( -1 0 .6 8 ) (8 .8 3 )] 0 .8 5 3 -1 .4 5 [( -1 1 .1 3 ) (8 .2 4 )] 0 .7 7 0 1 .3 8 [( -6 .7 3 ) (9 .4 9 )] 0 .7 3 9 -0 .5 3 [( -8 .2 3 ) (7 .1 7 )] 0 .8 9 4 -7 .0 8 [( -1 9 .6 4 ) (5 .4 7 )] 0 .2 7 1 t a b le 2 : u n iv a ri a te a n a ly s is , f im t o ta l, f im m o to r a n d l o s . *p < 0 .0 5 f im t o ta l a d m is s io n f im t o ta l d is c h a rg e f im m o to r a d m is s io n f im m o to r d is c h a rg e l e n g th o f s ta y ( l o s ) e s ti m a te ( s e ) t v a lu e p -v a lu e e s ti m a te ( s e ) t v a lu e p -v a lu e e s ti m a te ( s e ) t v a lu e p -v a lu e e s ti m a te ( s e ) t v a lu e p -v a lu e e s ti m a te ( s e ) t v a lu e p -v a lu e in te rc e p t 1 1 2 .3 8 ( 6 .7 0 ) 1 6 .7 7 0 .0 0 0 1 2 6 .3 1 ( 6 .8 4 ) 1 8 .4 5 0 .0 0 0 7 4 .6 7 ( 5 .7 5 ) 1 2 .9 8 0 .0 0 0 8 7 .8 2 ( 5 .6 8 ) 1 5 .4 7 0 .0 0 0 1 0 .5 9 ( 9 .8 2 ) 1 .0 8 0 .2 8 3 s e x ( f v s m ) -2 .6 3 ( 2 .2 3 ) -1 .1 8 0 .2 4 1 -1 .3 5 ( 2 .2 8 ) -0 .5 9 0 .5 5 5 -3 .9 4 ( 1 .9 1 ) -2 .0 6 0 .0 4 2 -2 .8 2 ( 1 .8 9 ) -1 .4 9 0 .1 3 7 -0 .2 4 ( 3 .2 7 ) -0 .0 7 0 .9 4 2 a g e -0 .5 ( 0 .1 ) -5 .0 3 < 0 .0 0 1 * -0 .3 5 ( 0 .1 ) -3 .4 7 0 .0 0 1 * -0 .4 1 ( 0 .0 9 ) -4 .8 1 < 0 .0 0 1 * -0 .2 7 ( 0 .0 8 ) -3 .1 8 0 .0 0 2 * 0 .2 5 ( 0 .1 5 ) 1 .7 2 0 .0 8 7 c v a -4 .3 9 ( 3 .0 8 ) -1 .4 2 0 .1 5 7 -4 .3 5 ( 3 .1 5 ) -1 .3 8 0 .1 7 0 -2 .7 5 ( 2 .6 5 ) -1 .0 4 0 .3 0 1 -2 .5 ( 2 .6 1 ) -0 .9 6 0 .3 4 0 2 .2 3 ( 4 .5 2 ) 0 .4 9 0 .6 2 2 d e m e n ti a -1 5 .0 1 ( 5 .4 4 ) -2 .7 6 0 .0 0 7 * -2 2 .7 3 ( 5 .5 6 ) -4 .0 9 < 0 .0 0 1 * -8 .8 4 ( 4 .6 7 ) -1 .8 9 0 .0 6 1 -1 4 .2 7 ( 4 .6 1 ) -3 .1 0 0 .0 0 2 * -6 .0 7 ( 7 .9 7 ) -0 .7 6 0 .4 4 8 h ig h b lo o d p re s s u re -3 .4 9 ( 3 .1 3 ) -1 .1 2 0 .2 6 6 -2 .9 3 ( 3 .2 ) -0 .9 2 0 .3 6 1 -1 .7 4 ( 2 .6 9 ) -0 .6 5 0 .5 2 0 -0 .5 5 ( 2 .6 5 ) -0 .2 1 0 .8 3 5 5 .3 4 ( 4 .5 9 ) 1 .1 6 0 .2 4 6 t a b le 3 : m u lt iv a ri a te a n a ly s is , f im t o ta l, f im m o to r a n d l o s . *p < 0 .0 5 https://doi.org/10.33137/cpoj.v3i1.33916 5 marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1.https://doi.org/10.33137/cpoj.v3i1.33916 issn: 2561-987x comorbidity and inpatient rehabilitation after amputation marquez et al. 2020 cpoj total cci or dichotomized cci (>6 or <6 score) were not associated with fim scores or los. the individual comorbidities that were shown to have an association with lower overall total fim scores at admission, after univariate analysis, were cerebrovascular disease (cva) (beta=-8.09, ci=[(-14.94) (-1.24)], p=0.022), dementia (beta=-23.46, ci=[(-34.63) (-12.30)], p<0.001), and hbp (beta=-9.46, ci=[(-16.26) (-2.65)], p=0.007). at discharge, cva (beta= -7.82, ci=[(-14.63) (-1.01)], p=0.026), dementia (beta= -28.85, ci=[(-39.57) (-18.12)], p<0.001), and hbp (beta= -7.78, ci=[(-14.59) (-0.96)], p=0.027) also showed an association with lower overall total fim scores. age was also associated with a lower overall total fim scores, at both admission (beta=-0.58, ci=[(-0.78) (-0.39)], p<0.001) and discharge (beta=-0.47, ci=[(-0.67) (-0.28)], p=0.000). sex showed an association with motor fim scores at admission such that females had lower scores (beta=-4.36, ci=[(-8.46) (-0.25)], p=0.040). at admission, the comorbidities associated with lower motor fim scores were dementia (beta=-16.39, ci=[(-25.84) (-6.95)], p=0.001) and hbp (beta=-6.41, ci=[(-12.11) (-0.70)], p 0.029). dementia was the only comorbidity to show an association with lower motor fim scores at discharge (beta -19.42, ci=[(-28.18) (-10.66)], p=0.000). age was negatively associated with motor fim scores at admission (beta -0.45, ci=[ (-0.61) (-0.29)], p<0.001) and discharge (beta -0.33, ci=[ (-0.49) (-0.17)], p<0.001). the remaining univariate analyses are presented in table 2. the factors that showed an association after the univariate analysis were then adjusted using multivariate analysis. for overall total fim scores at admission and discharge, dementia (admission p=0.007; discharge p<0.001) and age (admission p<0.001; discharge p=0.001) were shown to be inversely associated with overall total fim scores at admission after adjusting for confounders. age was negatively associated with lower motor fim scores at admission (estimate=-0.41, sd=0.09, p<0.001). being female was also inversely associated with lower motor fim scores at admission after adjusting for other confounders (estimate=-3.94, sd=1.91, p=0.042). dementia showed a negative association with motor fim at discharge (estimate=–14.27, sd=4.61, p=0.002). age also showed an association with poorer motor fim scores at discharge (estimate=-0.27, sd=0.08, p=0.002). table 3 includes remaining data from multivariate analysis. discussion the aim of this study was to describe comorbidities and the association with functional outcomes and length of stay in a cohort of patients with recent dysvascular limb loss undergoing inpatient non-prosthetic rehabilitation. there are three main findings from this study including 1: we identified the distribution of comorbidities using the cci in a cohort of patients with dysvascular limb loss admitted to inpatient rehabilitation, 2: age and dementia were two main factors associated with inpatient total and motor fim scores. 3: none of the individual comorbidities included in the cci were associated with los in this cohort undergoing non-prosthetic rehabilitation. many patients with limb loss entering inpatient rehabilitation programs have a burden of comorbidity in addition to their amputation. identification of which factors possibly hinder these patients during inpatient rehabilitation may assist in supporting these often complex and frail patients after amputation surgery. the distribution of demographic items in this dysvascular cohort was similar to prior studies. this study focused on patients with unilateral, transfemoral and transtibial limb loss with similar proportions of amputation level as well as average age in comparison with prior published work.21,22 a study conducted by taylor et al. reviewing patients with a major lea showed comparable ratios of patients with pvd and dm.23 of note, the three most frequent comorbidities were pvd, hypertension and diabetes which may underscore the need for medical management and secondary prevention in this population. this study is unique in that it examines the distribution of the cci items in patients with dysvascular limb loss and the association of each of these with inpatient non-prosthetic functional outcomes and length of stay. a study done by arneja et al.24 examined functional outcomes between patients with lea on dialysis and those not on dialysis. in their study only discharge fim scores were included, while our study contained both admission and discharge fim. additionally, their study examined various comorbidities but did not use an established index such as the cci. overall, in our study the total cci score did not show strong associations with functional outcomes in this cohort after multivariate analysis. fim changes and scores in this cohort generally reflect acquisition of independence with transfers and wheelchair mobility as this study did not examine prosthetic gait outcomes. a study conducted by stewart et al.25 provided evidence that patients with chronic conditions, such as cardiac and pulmonary disease, which are captured in the cci, do have an impact on function. the discrepancy between these findings and the absence of associations from our data could be explained by the nature of the patients in our study. these patients are medically complex and admitted to rehabilitation for only a short period of time to address non-prosthetic independence, so their progression may not be as evident with the outcome measures studied. conversely, the lack of differences attributed to specific comorbidities suggests that patients undergoing dysvascular amputation should still be offered non-prosthetic rehabilitation and can benefit from postoperative rehabilitation services regardless of comorbidity burden. moreover, there was no association of comorbidity with los suggesting that despite multiple comorbidities these patients can achieve a non-prosthetic functional level sufficient for discharge in a similar amount of time while admitted to inpatient rehabilitation. https://doi.org/10.33137/cpoj.v3i1.33916 6 marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1.https://doi.org/10.33137/cpoj.v3i1.33916 issn: 2561-987x comorbidity and inpatient rehabilitation after amputation marquez et al. 2020 cpoj while the total cci score was not associated with functional outcomes, our results show that dementia had a significant association with fim scores. dementia was found to have an inverse association with overall total fim, at both admission and discharge, and motor fim, at discharge. a limitation in our study was that there were only six patients who fit the inclusion criteria and had dementia upon admission. this finding is in accordance with past studies that have also demonstrated the relationship of cognitive impairment with poor functional outcomes after amputation.23,26-29 given, the very low number of patients with dementia in this data set, this association must be interpreted with caution as additional research with a larger sample size would be required to draw broader conclusions. age was another factor that was found to have an association with total and motor fim at both admission and discharge, with advanced age resulting in lower fim scores. this result is reasonable on account that it has been shown that patients are more likely to accumulate more medical conditions as they age.30 there are also additional studies that support the notion that advanced age is associated with poorer functional outcomes in patients with limb loss.27,31 however, another report by chopra et al. did not indicate an association between greater age and poorer ambulatory rates, which they attributed to their cohort size.18 limitations there was an association with dementia and functional outcomes however these patients represented a very small portion of the cohort and therefore future work should be directed to larger cohorts to better understand this association. furthermore, this study examined only the post-operative and non-prosthetic component of hospitalized rehabilitation patients with recent limb loss. while burden of comorbidity and specific comorbidities did not show associations with functional outcomes in this cohort it raises a number of additional points. while, one would hypothesize that a greater burden of comorbidity such as cardiovascular disease would impact ambulatory function, this cohort admitted for non-prosthetic rehabilitation was not impacted. this suggests that patients referred post-operatively after amputation who may never be prosthetic candidates may still benefit from inpatient rehabilitation to recover from surgery and restore independence prior to discharge. the cci reflects specific medical comorbidities however other factors may also play a role in rehabilitation after limb loss including the condition of the contralateral limb, visual impairments, delayed wound healing and mental health status, which could be explored in future studies. an important comorbidity which may disproportionately impact function and may not be fully reflected in the cci is that of end-stage renal disease in patients receiving hemodialysis. in patients living with limb loss who also receive dialysis, the mortality and functional outcomes are much poorer than those with dysvascular amputation and no hemodialysis.21,32 in order to better address this question in a non-prosthetic inpatient rehabilitation setting additional comparative studies (dyvascular amputation vs dysvascular plus dialysis) are needed. furthermore, this cohort represents one postamputation care model in canada and therefore the results may not be directly generalized to other forms of rehabilitation which can vary locally, nationally and internationally. conclusion in summary, we report the distribution of comorbidities in a cohort of patients with dysvascular limb loss using the cci. there was an association with dementia and functional outcomes as represented by the fim, however larger sample sizes will be needed to better explore this association. age did show negative associations with fim scores. there were no associations of comorbidity with inpatient rehabilitation length of stay. finally, given that there were no significant associations between total or specific comorbidities and functional outcomes and los in this cohort, medically complex patients with limb loss may still derive benefit from post-operative, non-prosthetic inpatient rehabilitation to restore independence prior to discharge from hospital. acknowledgements the authors would like to acknowledge the staff in the health information management office at providence healthcare for their support and assistance with this project. declaration of conflicting interests the authors have no conflicts of interest to declare. author contribution michelle g. marquez: completed data collection, data interpretation, literature review and manuscript writing. matthew kowgier: assisted in study design, led statistical analysis and contributed to manuscript development. w. shane journeay: conceived the study and design, data interpretation and manuscript writing. sources of support michelle g. marquez received a providence healthcare student research stipend. https://doi.org/10.33137/cpoj.v3i1.33916 7 marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1.https://doi.org/10.33137/cpoj.v3i1.33916 issn: 2561-987x comorbidity and inpatient rehabilitation after amputation marquez et al. 2020 cpoj ethical approval this was a retrospective cohort study and was approved by the research ethics board of providence healthcare and closed by the unity health toronto research ethics board. references 1.schofield cj, libby g, brennan gm, macalpine rr, 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tamiji j, hiebert bm, tappia ps, galimova l. functional outcomes of patients with amputation receiving chronic dialysis for end-stage renal disease. am j phys med rehabil. 2015; 94: 257-268. doi: 10.1097/phm.0000000000000259 25.stewart al, greenfield s, hays rd, wells k, rogers wh, berry sd, et al. functional status and well-being of patients with chronic conditions. results from the medical outcomes study. jama. 1989; 262(7): 907-913. doi:10.1001/jama. 1989.03430070055030 26.heinemann aw, linacre jm, wright bd, hamilton bb, granger c. prediction of rehabilitation outcomes with disability measures. https://doi.org/10.33137/cpoj.v3i1.33916 8 marquez m.g, kowgier m, journeay w.s. comorbidity and non-prosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.1.https://doi.org/10.33137/cpoj.v3i1.33916 issn: 2561-987x comorbidity and inpatient rehabilitation after amputation marquez et al. 2020 cpoj arch phys med rehabil. 1994; 75: 133-143. doi: 10.1016/00039993(94)90385-9 27.schoppen t, boonstra a, groothoff jw, de vries j, goeken ln, eisma wh. physical, mental, and social predictors of functional outcome in unilateral lower-limb amputees. arch phys med rehabil. 2003; 84: 803-811. doi:10.1016/s0003-9993(02)04952-3 28.frengopoulos c, burley j, viana r, payne mw, hunter sw. association between montreal cognitive assessment scores and measures of functional mobility in lower extremity amputees after inpatient rehabilitation. arch phys med rehabil. 2017; 98: 450-455. doi:10.1016/j.apmr.2016.06.012 29.williams rm, turner ap, green m, norvell dc, henderson aw, hakimi kn, et al. relationship between cognition and functional outcomes after dysvascular lower extremity amputation: a prospective study. am j phys med rehabil. 2015; 94(9): 707-17. doi: 10.1097/phm.0000000000000235 30.johnson vj, kondziela s, gottschalk f. pre and postamputation mobility of trans-tibial amputees: correlation to medical problems, age and mortality. prosthet orthot int. 1995; 19: 159164. doi:10.3109/03093649509167999 31.covinsky ke, palmer rm, fortinsky rh, counsell sr, stewart al, kresevic d, et al. loss of independence in activities of daily living in older adults hospitalized with medical illnesses: increased vulnerability with age. j am geriatr soc. 2003; 51: 451-458. doi:10.1046/j.1532-5415.2003.51152.x 32.serizawa f, sasaki s, fujishima s, akamatsu d, goto h, amada n. mortality rates and walking ability transition after lower limb major amputation in hemodialysis patients. j vasc surg. 2016; 64(4): 1018-25. doi: 10.1016/j.jvs.2016.03.452 https://doi.org/10.33137/cpoj.v3i1.33916 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.36349 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 stakeholder perspectives the digital o&p workshop opitz m.*, fröhlingsdorf p. mecuris gmbh, lindwurmstraße 11, 80337 münchen, germany. converging trends drastically digitalize o&p workshops digitalisation alone is just a meaningless buzzword. digitalisation is not a trend. in the scientific discipline of future studies,1 digitalisation would be tagged as a megatrend. megatrends span several sub phenomena we call (tech) trends like 3d scanning, 3d modelling and 3d printing. several of these trends currently converge and speed up change in orthotics & prosthetics (o&p) workshops up to a so-called tipping point. this means from a certain point in time or rather a rate of adoption, change fuels itself in a vicious circle and cannot be stopped anymore. popular examples are “flatten the curve” efforts versus the covid pandemic,2 “network effects” in social networks like facebook,3 global warming tipping points in climate change.4 in addition, covid-19 broke up traditional ways of working. such unforeseen events are called wildcards. wildcards drastically reduce the resistance to behavioural change and establish “new normals”. after such an event, things tend to snap “back to normal”. but, the longer the current crisis continues, the more routines have already changed permanently. the likelihood of future scenarios is strongly influenced by boundary conditions that are unlikely to change as rapidly as the fundamental needs of the end users, the regulatory framework and reimbursement. it is impossible to say what the future will look like. we can only describe scenarios and estimate their probabilities (figure 1). all probable scenarios currently foresee a fastpaced change towards a more digital manufacturing process. there is no “if”, just “when”. that means, all those who do not want to “suffer change” but instead create the future of o&p, now have to openly debate the “how”. in particular, how do we want the future of assistive device production to look like? is there a scenario in which all healthcare customers benefit: end users, providers and payors? this paper focuses on the o&p workshops and, in the first section, provides an overview of the trends around digitalisation that are about to converge and potential future adoption scenarios. the next section reviews how much boundary conditions prohibit or foster change in o&p care. in the final section, the impact of the covid wildcard will be assessed and we describe a desirable scenario that works as a north star for end users, providers and payors. we conclude with a call to action to all stakeholders, summarizing the next steps to be taken to increase the likeliness of this favourable scenario. open access volume 4, issue 2, article no.15. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract digitalisation is the megatrend in healthcare, not only since the pandemic. we are two european digital health experts and industry leaders in the field of orthotics and prosthetics (o&p) and in this article we explored what are the underlying trends driving the adoption of digitalisation for customisation of prosthetics & orthotics. we showed that several trends in 3d image capture (input step), 3d modelling (processing step) and 3d printing (output step) currently converge and thus fuel the rapid transformation of the o&p industry. in short outlooks, we rated the probability and timing of adoption rates across the upcoming couple of years. we furthermore reviewed the impact of boundary conditions set by regulators as well as the reimbursement system. towards the end of this article, we outlined a digital scenario of the near future by following around an orthotist during her work. we finished with a call-toaction targeting regulators, payors, prosthetists/orthotists, and patients to enable such a desirable future. citation opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 keywords digital transformation, central fab, digital process chains, fda, custom-made device, prosthetic feet, orthotic brace, quality assurance, additive manufacturing, trends * corresponding author manuel opitz, mecuris gmbh, lindwurmstraße 11, 80337 münchen, germany. e-mail: mo@mecuris.com orcid number: https://orcid.org/0000-0001-6098-1881 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.36349 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.36349 mailto:mo@mecuris.com https://orcid.org/0000-0001-6098-1881 2 opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 issn: 2561-987x the digital o&p workshop opitz m. & fröhlingsdorf p., 2021 cpoj special s p e c ia l i s s u e figure 1: framework for classifying scenarios based on their probabilities. converging 3d technology trends in digitizing the laboratory, we have to look at the three major steps of the process: 1.input (e.g. enabled by 3d scanning) 2.processing ( e.g. enabled by 3d modelling software) 3.output (e.g. enabled by 3d printing or cnc milling) input smartphone 3d scanning apps validated for o&p lead to data explosion 3d scanner adoption varies a lot by country. some countries like france with few o&p clinics serve large areas with central fabrication done by unskilled workers and, with favourable reimbursement systems, have almost full 3d scanner adoption. in germany, adoption is around 64.4%, with another 22% planning to use 3d scanners soon (figure 2), according to a 2017/18 survey among 118 german cpos.5 the us and canada are surprisingly nondigital in this category. figure 2: use of a simple, tablet-based 3d scanner. persons in image have given informed consent to publication. as of now, almost every cpo practicing in canada or the us has a 3d scanner in their jeans pocket. most current smartphones support 3d scanning but most generic 3d scanning apps6 for both android and ios, have not been validated for patient scanning. with the advent of more and more scanning apps specifically targeting o&p, validating patient scanning is beginning to happen,7,8 usability and scanning quality are being greatly increased and adoption rates are growing fast. since the iphone x,8 most models currently in use support these o&p scanning apps to an accuracy of ±1mm. in considering this, the tipping point for widespread adoption of ready-to-scan smartphones already lies in the past. the only question is, if the future follows a scenario with 3d scanning apps going mainstream in o&p in 2021 or 2022, or if some unforeseen event still changes this trajectory. processing workflow-based software-as-a-service (saas) modeling software pulverises entry barriers 3d modelling software has been used in all larger o&p workshops for several decades.9 however, two major factors prohibited widespread adoption in smaller workshops: 1. the high cost of $20’000 or $30’000 for a single license. annual maintenance fees add to the initial cost. 2. high expertise in cad design is needed. in many countries this is not threaded into the p&o educational curriculum and post-graduate training in these skills is costly, time-consuming and results in a lower level of competence than if it were integrated into the core p&o curriculum. additional minor factors include too few software updates, issues due to licenses being fixed to a single machine, high demand of processing power in a local machine, the requirement for specific tools like cad pens, etc. these issues are not exclusive to the o&p industry. in other industry areas, they already have been solved with modern cad tools. the high initial cost barrier was overcome by saas offerings. every cpo uses saas in their private life, e.g. through streaming services like netflix or spotify. the accountability of monthly fees for products is also increased thanks to that. on the technical side, subscription, webbased software that requires a monthly fee allows for access from any device, paving the way not only for saas, but also for faster updates and bug fixes, while reducing requirements for local hardware by allowing for processing directly in the cloud. modern software focuses on usability. for widespread adoption, a clean and intuitive user interface is key (figure 3). this runs counter to classic cad software offering up several dozen tools in one interface. workflowbased software, in contrast, follows the “natural”, manual way cpos are used to and expect (figure 3). time https://doi.org/10.33137/cpoj.v4i2.36349 3 opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 issn: 2561-987x the digital o&p workshop opitz m. & fröhlingsdorf p., 2021 cpoj special s p e c ia l i s s u e this modern software offers only the few really necessary tools required for a certain process step. faqs and feedback/help tools are also specific for every step.10 thus, little to no training is required and providers are “trained on the job”. again, cloud technology enables powerful smart features like an assisted posture correction of a scan or suggestions for functional form creation using machine learning.10 right now, such tools are primarily being offered to providers by startups. most focus on one application area, e.g. sockets11 or wrist braces.12,13 only a few enable several applications such as a classic cad tool for the orthotics and prosthetics side.10 however, the two leading manufacturers have also started in this direction, with ottobock investing in several startups14 and now developing their own workflow-based orthotics modelling software and össur, this year, announcing the purchase of parts of the socket modelling software from standard cyborg.15 the 7-digit investments made by dominant market players like ottobock and össur into process-based modeling software and the variety of new ideas by startups clearly indicate that the market is already tipping in this direction. fueled by the abundance of available 3d scanning data the remaining question is not if, but when 3d modelling software goes mainstream in o&p: 2022 or 2023 or 2024. output proliferating 3d printing service allows direct print of final design today, two ways of manufacturing dominate global production: injection moulding for mass production and manual hand crafting for custom products (figure 4). but, over the last few decades, mass customization enabled by the advent of new manufacturing technologies has begun to bridge the chasm between those two extremes. most relevant for o&p are computerized numerical control (cnc) milling and, more recently, additive manufacturing (am), often referred to as 3d printing. figure 4: two predominant ways of manufacturing dominated global production: injection moulding for mass production and manual hand crafting for custom products, with differing, clearly separated regulatory requirements. automation offers the highest leverage with large quantities, even for individual care. therefore, cnc milling machines were first and most successfully adopted in high volume individual care industries, as in dental or orthopedic insoles. however, severe restrictions on the complexity of the design limited the use of cnc milling machines. this was the case with the manufacturing of hearing aids, which could not be widely manufactured cnc milling, other than for some of the internal parts. therefore, the hearing aid industry was able to leapfrog cnc milling and went directly original scan corrected scan functional form finished orthotics figure 3: focus on usability: clean and intuitive user interface and follows the “natural”, manual way cpos are used to, with only a few tools that are required for a certain process step being visible. mass production e.g. injection moulding regulated as medical device manual production e.g. hand-crafting regulated as custom made device manufacturing of o&p devices till 1990 manufacturing technology continuum https://doi.org/10.33137/cpoj.v4i2.36349 4 opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 issn: 2561-987x the digital o&p workshop opitz m. & fröhlingsdorf p., 2021 cpoj special s p e c ia l i s s u e to am showing a concerted progress within a few years. using this strategy, the hearing aid industry was able to move to directly producing the final product without any mold or pre-product. by lowering costs per part, growing build volumes and increasing process stability, am has now reached maturity for o&p applications beyond orthopedic insoles. this finally enabled a fully digital process chain. before, it was aborted with the functional form that is milled and then used as a negative for thermo forming of an orthosis. this also meant a “dirty” workshop was still necessary. now, the (negative) functional form can be digitally “wrapped” with a (positive) final orthosis (or socket) design. this design, in turn, is directly manufactured using am. digitalising this last step saves a lot of working time for the provider, e.g. 3.7h for a foot orthosis.16 for larger providers, this quickly scales into a substantial economical advantage. the clear downside with am is the exponential cost scaling with increasing build volume. therefore, it is less a question if prosthetics or orthotics are economical to print. the question rather depends on the build size of the application. small o&p devices especially in pediatrics are already much cheaper to print compared to manual production, often even milling. this includes pediatric prosthetic feet, afos, dafos, night splints, wrist orthotics and baby helmets. for larger build volumes, cnc milling however remains the mass customization method of choice. this is true especially for large bracings for adolescents or adults that have to endure high stress and have to be built in one part, e.g. corsets. the paradigm shifts from subtractive to additive and also more unique selling propositions (usp): less waste. in times of rising environmental awareness, saving 1.5kg of waste and 1.6kg co2 equivalent in the manufacturing of a 0.5kg foot orthosis by using am instead of hot forming is important to many end users.16 a more long-term scenario includes the widespread shift in thinking from recreating traditional, subtractively manufactured devices with 3d printing towards more natural, generative designs.17 this shift in mindset rivals another scenario, in which a widespread availability of more materials, especially those known in the o&p space, lead towards another jump in adoption. in conclusion, the 7-digit investments made by dominant market players like hanger and ottobock as well as national purchasing associations e.g. in germany18 into industrial 3d printers and post processing machine parks clearly indicate that they expect additive manufacturing to gain a 2-digit market share in the very near future. most scenarios predict 3d printing as one more production tool and not the dominant technology overall, likely on par with cnc milling, injection moulding (figure 5) and, yes, some minor modifications still being done by hand. figure 5: schematic comparison of manufacturing technologies by cost-per-part and quantity of produced parts. due to the aforementioned high investment cost, most providers except the very large players like pohlig in germany or eastpoint19 in the us will either rely on a dominant oem for 3d printing, together with their peers cofund a 3d printer in a central fab20 e.g. within the framework of a purchasing association, or rely on a “neutral” 3rd party, the mushrooming number of 3d printing service bureaus. the scenarios for the future digital supply chains vary a lot by country and the competitive situation. it is likely that after the current adoption wave fueled by o&p-ready printing hubs and sinking costs, there will be another spike of adoption in a few years with the availability of more materials or the understanding of the new freedom of design enabled by am. boundary conditions regulation driven by fda separates custom + patientmatched device now that the fully digital process chains are capturing more and more medical markets, regulators are adjusting the framework in which manufacturers are allowed to operate. former regulations often did not cover these areas, or they allowed too much or too little legroom for manufacturers for patient safety. this caused a flurry of updated or new definitions and guidelines by national and international authorities. most productive has been the fda with advanced regulations for am of medical devices,21 software as a medical device (samd), in silico-trials (virtual testing) and more. the fda has worked alongside other national regulators in the international medical device regulators forum (imdrf) to assure a globally consistent definition for new terms like samd or patient-matched medical device. the imdrf has also filled the regulatory chasm between manual and mass manufacturing (figure 6), defining subtypes for personalised devices and providing technology examples for mass customisation like 3d printing: “it is now possible to produce medical devices, which are quantity https://doi.org/10.33137/cpoj.v4i2.36349 5 opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 issn: 2561-987x the digital o&p workshop opitz m. & fröhlingsdorf p., 2021 cpoj special s p e c ia l i s s u e individualised e.g. by additive manufacturing methods (3d printing) based on patient ct scans, on a commercial rather than a manual scale. the original ghtf documentation does not adequately address such devices.”22 further motivation was to make sure that the regulatory reliefs granted to custom made device manufacturers are not abused by industrial manufacturers to produce large quantities: “in other jurisdictions, the derogations were established with the intention that the number of custommade devices would necessarily be small, as they could only be used in special cases.”22 the fda explicitly limits the production of custom made devices "to no more than five units per year of a particular medical device".23 today, the imdrf distinguishes between 3 subclasses of personalised medical devices:22 1. custom-made products: a custom-made medical device on the written order of an authorised (medical) professional. this professional, on his own responsibility, gives the medical device specific design features, even if the design was developed with a manufacturer. in a nutshell, the provider controls the design step. it does not matter: 1.1. if the provider uses a 3rd party software to do so. 1.2. if the manufacturing is carried out by a 3rd party. 1.3. whether the device is hand-crafted or 3d printed. 2. patient-matched medical device: it is designed and manufactured under the responsibility of a manufacturer, even if the design was developed in consultation with an authorised healthcare professional. in a nutshell, a 3rd party manufacturer controls the design step. it does not matter: 2.1. if the provider supports with initial patient data or other design inputs. a practical example are plaster casts and/or 3d scan of a patient anatomy that is sent to a manufacturer who adapts a digital orthosis model to fit this patient anatomy and then returns a patient-specific manufactured orthosis. 3. adaptable medical device: a mass-produced product that is adapted, adjusted, assembled or shaped at the point of care, in accordance with the manufacturer's validated instructions. it does not matter: 3.1. whether the healthcare professional or the patient him/herself adapts or adjusts the device. a practical example are orthoses that are adapted to the patient through thermoforming, and/or are adjusted by the patient. this means that the globally valid definition distinguishes a patient-specific medical device from a custom-made product primarily because the design step is within the responsibility of the manufacturer, not the provider. the medical device coordination group (mdcg), a group formed on request of the european commission representing all member states, has just now adopted this definition in their mdcg 2021-03 guideline on custom-made devices.24 the trend scenario will thus see a continuation of new guidelines25 or updates of current ones, especially in the eu that was so far busy releasing the mdr. a harmonization of global definitions as national directives like the mdr or guidelines (eu, australia, fda) will probably take up to 5 years. canada also has not yet updated their regulations26 figure 6: regulatory overview by production technology: nowadays, there is no clear-cut border anymore between custom-made and massproduced devices, as mass-customisation has filled the gap. regulation cannot differentiate by production technology anymore, but needs to look at who is in charge of modelling and manufacturing. mass production e.g. injection moulding regulated as manual production e.g. hand-crafting regulated as custom made device mass customisation e.g. cnc, am regulated as manufacturing of o&p devices today manufacturing technology continuum https://doi.org/10.33137/cpoj.v4i2.36349 6 opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 issn: 2561-987x the digital o&p workshop opitz m. & fröhlingsdorf p., 2021 cpoj special s p e c ia l i s s u e and guidelines27 to account for mass customised devices. however, it is likely that the eu and fda have adopted the imdrf definitions, most other countries follow in their wake, which hopefully leads to a more unified regulatory landscape. more long-term, regulators might go after manufacturers misusing the custom device reliefs. it seems likely though that o&p manufacturers will benefit from a grace period compared to medical manufacturers in higher risk classes that pose a higher risk to patient safety. providers will always benefit from these reliefs. one scenario might be a care provider suing a large manufacturer that tries to grab a larger part of the value chain by not only offering modelling software or manufacturing services, but also internalising the design control. an alternative scenario might be a lawsuit by a competing manufacturer. reimbursement’s major impact could stifle or speed up digitalisation payors also want to benefit from this innovative process. the megatrend of ageing population in countries of the global north and thus more patients per capita forces payors to constantly lower reimbursement rates to rebalance overall healthcare costs. growing margins for providers that have adopted a digital process chain increases the likelihood for future scenarios in which payors will once more target o&p reimbursement levels. these scenarios will force manual manufacturing providers to either switch or shut down. the most likely scenario drives all providers to digitize their process of care giving in a short time frame, all but a few highly specialised providers that operate in a niche like pediatrics or para athletes and/or providers that increase their margin by out-of-pocket payments. however, since the year 2000, out-of-pocket payments have been constantly in decline in the us and canada.28 another long-term benefit for both regulators and payors is the perfect measurability of digital processes. providers will gain unprecedented quantitative insights into their manufacturing process. from scanning to printing, every step is monitored and evaluated. this enables a continuous improvement process as adopted in most industries by now,29 leading not only to less errors for providers, but also improved results for end users. less complications and better patient outcomes are also the goals of regulators and payors, reducing secondary costs like refittings, rehabilitation, and product replacements. in an unlikely scenario, payors therefore use their foresight to pay extra for custom made devices that were additively manufactured to drastically reduce adoption time and thus reap the benefits much faster. one example of this was the increase in reimbursement rates for o&p devices reinforced with carbon fibre for increased durability as the decisive factor for the sudden widespread adoption across all providers. conclusion covid wildcard due to its long duration and global impact for all citizens, the covid crisis has a tremendous impact, even compared to other wildcard events like 9/11 or the fukushima reactor catastrophe. this means the likelihood of future scenarios requiring more drastic behaviour changes increases, the longer this crisis endures. for end users, the sudden advent of telehealth will increase the demand for less physical appointments also in o&p care. this was clearly unthinkable at the beginning of 2020. taking a more active and informed approach towards healthcare will also increase demand towards providers to be treated accordingly. providers, in turn, would not have expected to work in home offices in o&p care. as most cpos do not have a plaster cast room at home, digital and distributed workshops suddenly became very important. these new tools are not part of the current reimbursement landscape. therefore, payors that have already been quick to provide temporary reliefs like waiving or accepting digital prescriptions or bonuses for protective equipment will also have to address such requests. tremendous costs on the one side were partly offset by drastically reduced spending for elective surgery and other healthcare treatments, evidently showing that healthcare spending is much less fixed than assumed for decades. desirable scenario for end users, providers and payors two paradigms seem constant for most future scenarios. first, the ageing population, which in turn leads to decreasing reimbursement rates by payors and thus increasing cost pressure for providers or out-of-the-pocket spending for end users. a second constant seems to be that digitalization as a technology will not replace human interaction and improve healthcare on its own, but empower all stakeholders with new tools and thus change how care is delivered in the future. based on these assumptions, we will draw a likely and desirable trend scenario for the o&p care of the new future in following: in 2022, tim needs a new afo as his old one broke yesterday during work. due to his impaired mobility, he schedules a quick video call with his orthotist emma. after a quick look at the orthosis, emma decides it is beyond even temporary repair, snaps a few pictures and files a complaint so the next afos will have a sturdier design for tim. the health insurance is informed, too. the next day, emma visits tim at home to collect the broken orthosis. as always, she takes inventory on joint mobility and muscle status and of course skin irritations, too. thanks https://doi.org/10.33137/cpoj.v4i2.36349 7 opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 issn: 2561-987x the digital o&p workshop opitz m. & fröhlingsdorf p., 2021 cpoj special s p e c ia l i s s u e to this checkup, emma identifies a recent pressure ulcer on the left side of his ankle, unrelated to the defect. she finally scans his foot with her mobile phone. tim picks green and yellow as colors for his new afo and a wavy pattern for the backside. when he is fully happy with the 3d preview, he adds his initials on the design just like an artist would do after expressing himself. with the technical information quickly collected, emma uses the rest of her time to understand tim’s recently changing activity profile and builds their relationship of trust. after visiting several more of her patients, emma receives approval to create a new orthosis from the payor thanks to her digital defect report. despite the premature defect, they are happy that tim is evidently very active and thus lowers the risk of higher follow up costs if his mobility decreases. emma uses 30 minutes in the afternoon to configure tim’s new afo on her workstation at home. she reloads the previous afo design for tim and asks the software to resize it based on today’s 3d scan. she then reinforces the defect area and reshapes the pressure point so she can add more padding for tim’s ankle. she then runs a quick computer simulation to assure the design changes have not increased the risk of failure or impaired the functionality of the device.30,31 she also invites colleagues at her workshop, bob and tommy, to review her design changes digitally (figure 7). when emma arrives in her workshop the next day, she receives a notification that due to an anomaly during the printing process, the material of the printed shell has slightly darkened. it seems to her like coloring issues in orthosis manufacturing have “successfully” transitioned from manual to digital manufacturing. thus, she quickly sends a new 3d preview to tim using a darker orange instead of the bright yellow so the darkened material does not shine through. tim is very happy with the new color. however, he had second thoughts about “signing off” his afo and asks emma to not color his initials too prominently, as he is afraid it might look too cocky. figure 7: review of design changes using digital tools. persons in image have given informed consent to publication. the next day, emma receives the colored shell and quickly inspects the quality and documents it with a few photos. she then adds the straps and padding, especially on the left side of the ankle. in the afternoon, she visits several end users, including tim. he tries out the new afo and is impressed with the consistent, perfect fit and the small improvement of the padding. emma captures a few videos of his gait to document the great functionality for her colleagues and the payor. tim also answers a quick satisfaction survey, stressing that he is not only very happy with the result of his new orthosis, but also the effortless complaint procedure with the provider and the payor. not only is he mobile again, but also a proud co-creator of his personalised assistive device. call to action to all end users: as described above, you can now take part in the aesthetic design of your custom patient aid. this is just one example of how digitalisation empowers you to become the co-creators of your own devices, together with your trusted provider. to providers: if you care more about patient outcomes than the manual craftsmanship in your workshop, digitalisation enables you to shift your focus while increasing customer satisfaction and productivity. no software or 3d scanner is going to replace the unique bond you have with your clients, but if you prefer tinkering over caring for patients, payors will make your life much more difficult in the future. to payors: to reap the true benefits of digitalisation in o&p care, a small reimbursement incentive drastically increases adoption time, thus lowering long-term post-treatment costs thanks to high and consistent health outcomes. to regulators: despite not being a healthcare customer, you have the power to guide efforts for improved patient outcomes without harming innovation. the main need is not for additional regulation, but further, more tangible guidelines, ideally globally harmonised. this stretches from samd to mass customisation and fabrication to prevent the misuse of custom made device reliefs. acknowledgements none. declaration of conflicting interests the authors are members of the executive management team and/or shareholders of the munich-based company mecuris. the mecuris solution platform offered by mecuris contains digital tools as described in the article. sources of support parts of this article have been enabled through the research project sigma3d. this includes the cited works on regulation of custommade devices and the mdr of ann-kathrin carl from university of applied science münster. mecuris is the project leader and the https://doi.org/10.33137/cpoj.v4i2.36349 8 opitz m, fröhlingsdorf p. the digital o&p workshop. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 issn: 2561-987x the digital o&p workshop opitz m. & fröhlingsdorf p., 2021 cpoj special s p e c ia l i s s u e project is funded by the german federal ministry of education and research under the funding code 16sv8386. the responsibility for the content of this publication lies with the authors. references 1.futures studies [internet]. wikipedia. 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volume 4, issue 2, no.15. https://doi.org/10.33137/cpoj.v4i2.36349 issn: 2561-987x the digital o&p workshop opitz m. & fröhlingsdorf p., 2021 cpoj special s p e c ia l i s s u e https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/dhpmps/alt_formats/hpfb-dgpsa/pdf/acces/sap-md-dg-as-im-ldeng.pdf#page=20 28.out-of-pocket expenditure (% of current health expenditure) canada, united states [internet]. the world bank. [cited 2021 feb 10]. available from: https://data.worldbank.org/indicator/sh.xpd.oopc.ch.zs?locati ons=ca-us 29.kaizen [internet]. wikipedia. [cited 2021 feb 10]. available from: https://en.wikipedia.org/wiki/kaizen 30.verbesserter patientennutzen: digitale abmessung und 3d modellierte orthesen [internet]. german federal ministry of education and research. sigma3d. [cited 2021 feb 10]. available from: https://www.interaktive-technologien.de/projekte/sigma3d 31.interdisciplinary research project for the digitalization of orthotics [internet]. mecuris. sigma3d. [cited 2021 feb 10]. available from: https://www.mecuris.com/sigma3d-projekt?lang=en authors scientific biography before starting several medtech ventures, manuel opitz studied industrial & bioengineering at rwth aachen and trinity college dublin (msc). after first experiences in innovation and operations management in germany, china and switzerland, he finished postgraduate studies in economics at the trinational cdi in paris (mba). afterwards, he focused on medical technologies as a patent broker and startup consultant. he successfully raised funds for three different medtech ventures. as co-founder of mecuris (ceo & coo), he analyses orthopaedic manufacturing processes to unlock digitalisation potential for orthotists/prosthetists and patients. with his newest venture (ceo), he aims at reducing diagnostic errors and patient visits using ai software as a second opinion for doctors. as a regular speaker at healthcare conferences (otworld, ispo, …), innovation (tedx) and startup conferences, he works on bridging the gap between digital technologies and the healthcare system. he is co-author of an industry guideline on “digital process chains in medical technology” and contributed to books on 3d printing as well as digital business models in the healthcare sector. master craftsman and certified prosthetist & orthotist peter fröhlingsdorf gained hands-on experience in patient care with his own handicraft production for 10 years before he successfully took over the responsibility for setting up a central production for orthopaedic and orthopaedic shoe technology aids in one of the largest medical supply stores in germany. there he later expanded and developed the area of children's and youth care as managing director. further career stages include 5 years of sales experience with an icelandic prosthesis manufacturer and setting up a european sales hub and force for assistant robots of a canadian manufacturer. peter fröhlingsdorf has been ceo of mecuris gmbh since january 2020. he is a regular lecturer at the federal college for orthopaedic technology in dortmund, otworld, rehakind, focus cp, accident insurance association and more. he is also 2nd chairman and treasurer of cerebral palsy network e.v. and is passionate about innovation in orthopaedic technology. https://doi.org/10.33137/cpoj.v4i2.36349 https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/dhp-mps/alt_formats/hpfb-dgpsa/pdf/acces/sap-md-dg-as-im-ld-eng.pdf#page=20 https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/dhp-mps/alt_formats/hpfb-dgpsa/pdf/acces/sap-md-dg-as-im-ld-eng.pdf#page=20 https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/dhp-mps/alt_formats/hpfb-dgpsa/pdf/acces/sap-md-dg-as-im-ld-eng.pdf#page=20 https://data.worldbank.org/indicator/sh.xpd.oopc.ch.zs?locations=ca-us https://data.worldbank.org/indicator/sh.xpd.oopc.ch.zs?locations=ca-us https://en.wikipedia.org/wiki/kaizen https://www.interaktive-technologien.de/projekte/sigma3d https://www.mecuris.com/sigma3d-projekt?lang=en guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 issn: 2561-987x volume 2, issue 1 2019 (online) case series all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn 2561-987x https://doi.org/10.33137/cpoj.v2i1.33061 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 1 open access continuous radiofrequency ablation of painful residual limb neuroma volume 2, issue 1, article no.4, november 2019 case series ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputation a retrospective case series guo s.1*, mansour r.2, henderson slater d.1 1 oxford centre for enablement, nuffield orthopaedic centre, oxford, uk. 2 department of radiology, nuffield orthopaedic centre, oxford, uk. introduction post-amputation pain is very common after limb amputation, and residual limb neuroma is a significant cause of this, which can include both pain around the residual limb and phantom pain. however, it is also recognised that many individuals with limb amputation have neuromas that are not apparently causing pain.1 neuromas are commonly seen as incidental findings on scans carried out for other clinical reasons, and the precise degree of correlation between the presence of a neuroma and phantom pain due to the neuroma is not known.2 residual limb neuroma-associated pain can be difficult to treat and is often managed using an interdisciplinary approach with a combination of neuropathic analgesia, abstract background: residual limb neuromas are a significant cause of post-amputation pain. there is little knowledge concerning ultrasound-guided (us) radiofrequency ablation (rfa) as treatment. objective: to investigate us-guided rfa for neuroma associated pain in individuals with limb amputation. methodology: the notes of nine consecutive patients were retrospectively reviewed. information obtained included neuroma size and nerve, rfa duration/temperature, pain scores, analgesic requirements and ease/comfort of prosthetic use. eight patients had lower-limb amputations and one had a trans-radial amputation. all except one, underwent diagnostic us-guided steroid injection to confirm the neuroma as the source of pain, prior to rfa. results: six patients reported significant reduction in pain scores (defined as at least 50% reduction) and an improvement in comfort/ease of wearing their prosthetic limb, with no adverse effects. three of these six patients also reported a reduction in analgesic requirements. of the three remaining patients – one had a large sciatic nerve neuroma that was eventually surgically excised, another had confounding pain from an adjacent bony spur, whilst the third patient did not receive a routine diagnostic steroid injection prior to rfa. conclusions: our findings suggest that us-guided rfa is safe and effective for small to medium-sized residual limb neuroma associated pain in individuals with limb amputation. it can reduce pain and analgesic requirements, improve comfort/ease of wearing the prosthesis and potentially avoid surgical excision. we recommend patients should undergo a diagnostic steroid injection prior to rfa to confirm that the neuroma is the source of pain. citation guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i 1.33061 keywords prosthetics, rehabilitation, amputations, neuroma, pain, radiofrequency ablation *corresponding author shigong guo, llm msc(orth eng) mrcs, specialty registrar in rehabilitation medicine oxford centre for enablement, nuffield orthopaedic centre, oxford, uk. email: shigong@doctors.org.uk doi: https://doi.org/10.33137/cpoj.v2i1.33061 article info received: september 10, 2019 accepted: october 21, 2019 published: november 3, 2019 https://doi.org/10.33137/cpoj.v2i1.33061 https://doi.org/10.33137/cpoj.v2i1.33061 https://doi.org/10.33137/cpoj.v2i1.33061 mailto:shigong@doctors.org.uk https://doi.org/10.33137/cpoj.v2i1.33061 guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 2 continuous radiofrequency ablation of painful residual limb neuroma volume 2, issue 1, article no.4, november 2019 https://jps.library.utoronto.ca/index.php/cpoj/index physiotherapy, adjustments to the prosthesis, prosthetic counselling and eventual surgical excision.3 neuroma-associated pain could be due to residual limb pain or phantom pain or a combination of both. residual limb pain (also known as stump pain) has been described as a sharp, burning, ‘electric shock’-like pain which the patient often attributes to an incision site around the residual limb or perceives the pain originating deep in the residual limb.4 its incidence has been reported in up to 74% of individuals with limb amputation.5 this is different from phantom pain, which has been described as a painful or unpleasant sensation in the distribution of severed limb after amputation. it can be classified as either neuropathiclike (sharp, shooting, electric shock type pain) or nociceptive-like (dull, squeezing, and cramping) or a combination of both. it has been reported in 85% of patients with limb amputation.4 although the mechanism of interaction is not fully understood, residual limb pain and phantom pain often coexist post-amputation and montoya et al have reported a significant correlation between the severities of these two types of pain in individuals with limb amputation.6 there is a paucity of studies in the literature concerning ultrasound-guided (us) radiofrequency ablation (rfa) as a treatment for residual limb neuroma pain in terms of its effectiveness in reducing pain and analgesic requirements, improving comfort when wearing prosthetic limbs and reducing the need for surgical intervention this study aims to investigate the effects of us-guided rfa as a treatment for residual limb neuromaassociated pain. after retrospectively reviewing the patient case notes, we retrieved data on the safety, efficacy, side effects, and complications of us-guided rfa in the treatment of painful residual limb neuroma. methodology retrospective review the clinical notes and imaging of nine consecutive patients who underwent rfa for residual limb neuroma-associated pain during the period 2015 – 2019 were retrospectively reviewed. information obtained included: 1. patient demographics 2. site of amputation 3. reason for amputation 4. size of neuroma and nerve involved 5. phantom pain (if any) 6. rfa duration, temperature and pulsation (i.e. continuous versus alternating) 7. pain (numerical rating scale – nrs) scores – at 3-8 months pre-rfa, immediately pre and post rfa, 1 day, 2 days, 2 weeks and 3 months post-rfa. 8. analgesic requirements preand post-rfa 9. adverse effects of rfa (if any) 10. comfort and ease of using prosthetic limb preand post-rfa. after obtained the nrs pain scores at the aforementioned intervals, statistical analysis was performed using matlab (mathworks, ma, usa). in order to assess the expected value and variation in pain scores amongst the patients, the mean pain score and standard deviation at the different time intervals (preand post-treatment) for all nine patients and for the six successfully treated patients were calculated. in order to determine the statistical significance of the change in pain scores, wilcoxon signed-rank test was used to calculate the p-values when examining the change in pain scores from initial presentation and the different time intervals (preand post-treatment). wilcoxon signedrank test was selected because of the small sample size and that pain scores cannot be assumed to be normally distributed. written informed consent was obtained from each patient prior to the rfa procedure. as this is a retrospective review of past patient notes, ethical approval was not needed. radiofrequency ablation assessment and protocol 1. the initial assessment in the outpatient clinic of the patients with limb amputation was performed by a consultant rehabilitation physician (dhs) or a senior trainee under the supervision of the consultant at which initial pain scores were taken. 2. through magnetic resonance imaging (mri), the presence a neuroma was confirmed as well as its site, size and nerve involved. 3. the patients were then reviewed again post-mri scanning by the consultant rehabilitation physician and referred to a single consultant musculoskeletal radiologist (rm) who performed us-guided rfa treatment. 4. the patients waited between 3-8 months for their usguided rfa treatment. 5. on the day of treatment, pain scores were taken again before the rfa. 6. the patient was placed in a comfortable position (supine for the lower limb, sitting for the upper limb). the skin was then prepped with isopropyl alcohol solution and draped. 7. the linear high-frequency ultrasonic transducer (513mhz; vfx13-5, siemens ag) was covered with a sterile transparent sticker and placed transversely over the area of focal tenderness as reported by the patient. 8. on imaging with a high-resolution sonography machine (acuson antares; siemens ag, munich, germany), the presence of the neuroma was reconfirmed on both transverse and longitudinal views by rotating the transducer by 90 degrees. the neuroma was visualised https://doi.org/10.33137/cpoj.v2i1.33061 https://jps.library.utoronto.ca/index.php/cpoj/index guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 3 continuous radiofrequency ablation of painful residual limb neuroma volume 2, issue 1, article no.4, november 2019 https://jps.library.utoronto.ca/index.php/cpoj/index as a well-defined hypoechoic lesion involving the affected transected nerve (figure 1, figure 2). figure 1: us image of 11x6mm neuroma along the ulnar nerve in the residual limb of a patient who had a trans-radial amputation (patient 1). figure 2: us image of 10x7 mm neuroma along the common peroneal nerve in the residual limb of a patient who had a transtibial amputation (patient 2). 9. after attaching to a radiofrequency generator (neurotherm nt1000; morgan innovation and technology ltd, hampshire, uk) (figure 3), a 10 cm disposable radiofrequency electrode was placed into a compatible 10 cm radiofrequency straight cannula (st jude medical, plymouth, mn, usa) with a 5 mm active tip. with the transducer placed vertically to give a longitudinal view of the neuroma, this tip was advanced towards the nerve just proximal to the neuroma with the aim of reproducing the pain and confirming the site. under direct imaging, 40 mg triamcinolone acetonide mixed with 2 ml 0.25% bupivacaine was injected around the nerve just proximal to the neuroma. relief of the pain a few minutes after administration of the steroid confirmed the target neuroma. if neuromaassociated pain was confirmed using this technique, the tip of the electrode-cannula would be advanced into the affected neuroma (figure 4). rfa would then be carried out 90°celsius continuously for 9 minutes. 10. after undergoing rfa, pain scores were taken immediately post-procedure, via telephone follow up 1 day, 2 days and 2 weeks post-rfa, and via face to face follow up in the rehabilitation clinic 3 months post-rfa. the patients were asked to give the maximum pain score that they felt on the day of assessment. figure 3: neurotherm nt1000 radiofrequency generator figure 4: advancing the electrode-cannula (arrowed) into the neuroma for rfa under us guidance results pre-treatment data there were 9 patients (3 men and 6 women) aged between 30 and 69 years (mean 45 years). eight had lower limb amputations (5 had transtibial, 2 transfemoral, 1 hip disarticulation) and one had a trans-radial amputation. four of these patients underwent amputation due to trauma, two due to peripheral vascular disease, two due to neoplasm and one due to infection. the patients underwent amputation between 1 and 26 years ago (mean 7 years). https://doi.org/10.33137/cpoj.v2i1.33061 https://jps.library.utoronto.ca/index.php/cpoj/index guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 4 continuous radiofrequency ablation of painful residual limb neuroma volume 2, issue 1, article no.4, november 2019 https://jps.library.utoronto.ca/index.php/cpoj/index table 1: patient demographics, pre-rfa pain and neuroma characteristics. on initial presentation to the outpatient rehabilitation clinic, seven patients reported a pain severity of 10/10 on the nrs score, one had a pain score of 9 and one had a pain score of 7. all nine patients reported pain around the residual limb, and six of these patients also complained of phantom pain in addition to their residual limb pain. the residual limb condition in all these patients was stable with no local inflammation or acute skin or soft tissue changes. all patients reported discomfort and difficulty wearing their prosthetic limb due to pain. patient demographics, prostheses suspension and weight-bearing characteristics, pre-rfa pain and neuroma characteristics are illustrated in table1. the duration of pain symptoms from onset to initial presentation in clinic ranged from three months to six months with a mean of four months. apart from simple and/or neuropathic analgesics, the patients had not received any other conservative pain-relieving interventions. through magnetic resonance imaging (mri) and ultrasound scanning, three patients were found to have neuromas involving the tibial nerve, three involved the sciatic nerve, one involved the common peroneal nerve, one the superficial peroneal nerve and one the ulnar nerve. the largest neuroma was 30x30mm and involved the sciatic nerve (figure 5). the smallest neuroma was 10x6mm and involved the tibial nerve. the nine patients were consecutively referred from the prosthetic rehabilitation team to the radiology team for consideration for ultrasound-guided rfa. on the day of treatment, pain scores were taken again before the rfa – six patients reported a score 10/10 for their pain, two patients reported a score 8/10 and one patient reported a score 7/10. in all cases, the patient was able to point to a focal area of tenderness over the residual limb that was elicited on direct palpation. in the six patients with phantom pain, palpating over the focal area of tenderness led to a positive tinel’s sign along the course of the affected nerve in the phantom limb. on direct pressure from the transducer, the pain reported by the patient in all cases was able to be reproduced. post-treatment results after undergoing rfa, pain scores were taken immediately post-procedure, via telephone follow up 1 day, 2 days and 2 weeks post-rfa, and via face to face follow up in the rehabilitation clinic 3 months post-rfa (table 2). all patients bar one underwent a diagnostic us-guided steroid injection to confirm that the neuroma was the source of the pain, prior to rfa. six patients reported a significant reduction in pain nrs scores – defined as at least 50% reduction,7 sustained over at least 3 months with no adverse effects. three of these six patients also reported a reduction in analgesic requirements, two patients did not have any analgesic pre and post-rfa and one patient did not report any significant change in analgesic demands. all of the six patients reported an improvement in comfort in wearing their prosthetic limb. amongst these six patients who reported significant pain relief, three of them also had pre-existing phantom pain and found that rfa also resolved their phantom pain completely. p a ti e n t s e x a g e a m p u ta ti o n s it e c a u s e o f a m p u ta ti o n y e a rs s in c e a m p u ta ti o n p ro s th e s is s u s p e n s io n m e c h a n is m p ro s th e s is s o c k e t w e ig h t b e a ri n g c h a ra c te ri s ti c s p a in s c o re (n r s ) a t p re s e n ta ti o n a d d it io n a l p h a n to m p a in a t p re s e n ta ti o n p a in c a u s e s d is c o m fo rt /d if fi c u lt y w e a ri n g p ro s th e s is s iz e o f n e u ro m a (m m ) o n m r i n e rv e i n v o lv e d 1 f 67 transradial peripheral vascular disease 6 suction non-weight bearing 10 + yes 11x6 ulnar nerve 2 m 30 transtibial trauma 2 sleeve patellar tendon bearing 7 + yes 10x7 common peroneal nerve 3 m 27 transtibial trauma 7 elevated vacuum total surface bearing 10 yes 14x8 tibial nerve 4 f 37 transtibial trauma 10 pin lock (clutch) total surfacing bearing 10 yes 10x6 tibial nerve 5 m 47 hip disarticulation neoplasm 26 strap ischial weight bearing 10 + yes 30x30 sciatic nerve 6 f 49 transtibial peripheral vascular disease 6 sleeve patellar tendon bearing 9 + yes 12x10 tibial nerve 7 f 42 transfemoral neoplasm 1 belt ischial weight bearing 10 yes 18x13 sciatic nerve 8 f 69 transtibial infection 5 sleeve patellar tendon bearing 10 + yes 12x12 superficial peroneal nerve 9 f 36 transfemoral trauma 3 lanyard ischial weight bearing 10 + yes 19x15 sciatic nerve https://doi.org/10.33137/cpoj.v2i1.33061 https://jps.library.utoronto.ca/index.php/cpoj/index guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 5 continuous radiofrequency ablation of painful residual limb neuroma volume 2, issue 1, article no.4, november 2019 https://jps.library.utoronto.ca/index.php/cpoj/index table 2: results of rfa treatment in terms of changes in pain, analgesic requirements and ease/comfort of prosthesis use. of the three other patients who did not report a significant sustained reduction overall pain, one had a large sciatic nerve neuroma (figure 5) which was eventually successfully treated with surgical excision. figure 5: us image of 30x30 mm neuroma along the sciatic nerve in a patient who had a hip disarticulation (patient 5). another patient was found to have a bony spur adjacent to the neuroma at the time of the ultrasound-guided rfa which could have contributed to her pain, whilst the third patient reported an initial reduction in pain for 1-week post rfa but then experienced a return of the pain including heightened phantom sensation. interestingly, the third patient did not receive a routine diagnostic steroid injection prior to undertaking the rfa as we had confidently, but erroneously, assumed that the large neuroma was the cause of her pain. apart from failure to relieve the pain in three of the patients, no complications of rfa were reported in all nine patients and no pathological changes were observed at the distal end of the targeted nerve during and after rfa. routine regular follow up was carried out up the threemonth mark post-rfa, after which the patients were given the option to return to the clinic through a self-referral (via an open appointment) or re-referral via their general practitioner/family physician if there were any further problems with pain or discomfort. at the time of writing, none of the six successfully treated patients chose to return to clinic and thus we have not observed any reports of recurrence in the longer term. statistical analysis statistical analysis was performed using matlab (mathworks, ma, usa). the mean pain score and standard deviation at the different time intervals (preand post-treatment) for all nine patients and for the six successfully treated patients were calculated. this data is tabulated in table 3 (a and b) and graphically illustrated in appendix. wilcoxon signed-rank test calculated the p-values of the changes in pain scores at initial presentation and the different time intervals preand post-treatment (immediately before treatment, immediately after treatment, 1 day, 2 days, 2 weeks and 3 months posttreatment) for all nine patients and for the six successfully treated patients (table 3,a,b). the p-values comparing the change in pain scores at initial presentation and from day 1 post-treatment were consistently below 0.05, which is strongly against the null hypothesis and suggests a statistically significant reduction in pain scores.8 interestingly, the p-values for all nine patients were lower than the p-values for the six successfully treated patients. this could be explained by two factors. firstly, patient 1 reported an initial complete resolution of her pain (from 10 p a ti e n t p a in s c o re (n r s ) im m e d ia te ly p re -r f a p a in s c o re (n r s ) im m e d ia te ly p o s tr f a p a in s c o re (n r s ) d a y 1 p o s tr f a p a in s c o re (n r s ) d a y 2 p o s tr f a p a in s c o re (n r s ) 2 w e e k s p o s tr f a p a in s c o re (n r s ) a t 3 m o n th s p o s tr f a p h a n to m p a in p o s tr f a c h a n g e s i n a n a lg e s ic re q u ir e m e n ts p re a n d p o s t r f a im p ro v e d e a s e a n d c o m fo rt o f w e a ri n g p ro s th e s is p o s tr f a a d v e rs e e ff e c ts / o th e r is s u e s 1 10 0 0 0 10 10 + no change (still on gabapentin 300mg tds) no did not have diagnostic steroid injection pre-rfa 2 8 7 6 5 0 0 gabapentin reduced from 600mg tds to 300mg tds yes none 3 7 2 0 0 0 2 did not take analgesics preor post rfa yes no 4 10 0 0 0 0 0 did not take analgesics preor post rfa yes no 5 10 9 8 7 2 10 + did not take analgesics preor post rfa no required surgical excision of neuroma 6 10 9 8 1 0 1 gabapentin reduced from 600mg tds to 300mg tds yes none 7 10 7 7 7 10 6 no longer taking oxycodone 5mg bd no adjacent bony spur 8 8 8 8 8 6 3 paracetamol1g qds moved to prn yes none 9 10 5 1 1 unknown 0 + no change (still on pregabalin 75mg on, amitriptyline 25mg on) yes none https://doi.org/10.33137/cpoj.v2i1.33061 https://jps.library.utoronto.ca/index.php/cpoj/index guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 6 continuous radiofrequency ablation of painful residual limb neuroma volume 2, issue 1, article no.4, november 2019 https://jps.library.utoronto.ca/index.php/cpoj/index to 0 on the nrs) followed by a full return of her pain two weeks later. this outlier may have unduly influenced the p-value calculations. secondly, reducing the already small sample size from nine patients to an even smaller sample of six patients could also have increased the p-values. table 3: mean pain score, standard deviation (sd) and p-values at different time intervals preand post-rfa of all nine patients (a) and six successfully treated patients (b). a b time interval mean sd pvalue mean sd pvalue at presentation 9.56 1.01 1.0000 9.33 1.21 1.0000 immediately prerfa 9.22 1.20 0.6250 8.83 1.32 0.6250 immediately post-rfa 5.22 3.67 0.0156 5.17 3.55 0.1250 day 1 4.22 3.83 0.0039 3.83 3.92 0.0313 day 2 3.22 3.46 0.0039 2.50 3.27 0.0313 2 weeks 3.50 4.21 0.0156 1.58 2.58 0.0313 3 months 3.56 4.13 0.0156 1.00 1.26 0.0313 discussion neuroma formation is common after limb amputation. the type commonly found post-amputation are terminal neuromas which can occur when the proximal nerve terminal is severed during the surgery, after which apoptosis occurs in the distal axons of the nerve.9 in order to maintain the congruity of the axon, schwann cells stimulate new growth of adjacent axons. however, in cases where the defect of the axon is too long to overcome by the aforementioned mechanism, the proximal axons will growth in multiple directions to overcome the defect, giving a bulbous appearance to the neuroma that is visualised on mri and ultrasound imaging.9 residual limb neuroma-associated pain can be difficult to treat. a multidisciplinary approach is often required in terms of adjustments to the liner and socket by the prosthetists, psychological input, gait retraining by physiotherapy, oral analgesic changes, specialist input by the pain team and ultimately surgical excision with its associated operative risks and risk of recurrence.10 there is a paucity of studies in the literature concerning ultrasound-guided rfa in the treatment of residual limb neuroma-associated pain in individuals with limb amputation. these have mainly been isolated case reports.10-12 there has been one previous case series carried out by zhang et al of 13 patients exploring the use of alcohol neurolysis in combination with rfa in residual limb neuroma associated pain.13 the authors found that in patients whose neuroma pain was resistant to alcohol neurolysis, rfa provided an effective alternative in terms of pain relief. rfa may be continuous or pulsed. continuous rfa uses high-frequency alternating current which leads to coagulative necrosis of the neuroma. pulsed rfa utilises the current in short 20 millisecond bursts with a half-second respite in between to allow for heat dissipation.14 in these isolated case reports, pulsed rfa was performed at 42°c for 120-240 seconds each in two to three separate intervals, whereas in zhang et al case series pulsed rfa was carried out at 80°c for 240 seconds each in two separate intervals. and the authors suggested this gave more consistent favourable results in terms of longer-term improvements in pain scores up to 6 months postprocedure. there is currently no consensus on the temperature and duration for rfa or whether it should be continuous or pulsed. our study differs from the existing literature in that we have used continuous rfa at 90°c for nine minutes (540 seconds) which is in line with our local hospital practice. in addition to the higher temperature and longer duration, we have found that a single intervention of continuous rfa was sufficient in most of our patients in terms of sustained long-term pain relief without the need for multiple rfa treatments as seen zhang et al’s study involving pulsed rfa. continuous rfa is known to be more effective than pulsed rfa in the treatment of facet joint-related low back pain 14-16 and a similar trend may also be apparent in residual limb neuroma associated pain in individuals with limb amputation. in the six patients who reported significant pain relief postrfa, three of them also had pre-existing phantom pain and found that rfa also resolved their phantom pain completely. there are many theories as to where phantom pain originates including peripheral, spinal and central nervous system contributors. our study supports the theories that there is a peripheral contribution. this is also supported by as zhang et al who note that in clinical practice residual limb pain and phantom pain are often intertwined and can be difficult to separate. severing of peripheral nerves during amputation can lead to hyperexcitability and spontaneous generation of action potentials from the cut nerve, which in turn can cause phantom pain. this theory could explain the growing use of peripheral nerve blocks to treat phantom limb pain.17-19 undergoing a diagnostic steroid injection prior to the rfa may be a confounding factor in terms of the patient’s pain relief. us-guided steroid injections have been used to treat painful residual limb neuroma with promising early results in a few isolated case reports and a small case series.20-22 but again, like with rfa and residual limb neuromas, the number of studies and the number of patients treated could be too small to infer any concrete consensus. as mentioned, of the three other patients who did not report a significant reduction in pain, one had a large sciatic nerve neuroma that was eventually successfully treated with surgical excision, one had confounding pain from an https://doi.org/10.33137/cpoj.v2i1.33061 https://jps.library.utoronto.ca/index.php/cpoj/index guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 7 continuous radiofrequency ablation of painful residual limb neuroma volume 2, issue 1, article no.4, november 2019 https://jps.library.utoronto.ca/index.php/cpoj/index adjacent bony spur (figure 6) that was also eventually surgically excised, whilst the third patient did not receive a routine diagnostic steroid injection confirming the neuroma as the source of the pain prior to undertaking rfa. this sciatic nerve neuroma (30 x 30 mm) was almost double the size of the second-largest neuroma in our study. this might suggest that rfa would be better suited to treating pain originating from small to medium size neuromas. for larger neuromas, surgical intervention may be an inevitability. dumanian et al carried out a randomised controlled trial of 28 individuals with limb amputation with painful residual limb neuroma assigned to either traditional surgical excision or target muscle reinnervation (tmr).23 during surgical excision of a neuroma, tmr involves identifying using a nerve stimulator nearby sensory and motor nerves innervating surrounding muscle and suturing the nerves to a surgically divided distal nerve (e.g. tibial nerve sutured to the distal segment of the motor nerve to the soleus). this nerve transfer technique aims to facilitate reinnervation as close as possible to resembling physiological innervation thus potentially inhibiting the pathological central reorganisation of neuropathic pain mechanisms.24 the authors found that tmr provided greater pain relief for both residual limb pain and phantom pain on the nrs compared with traditional surgical excision of the neuroma.23 the same research group also conducted a multicentre cohort study comparing 51 patients undergoing major limb amputation with immediate tmr with 438 unselected standard major limb amputation patients. the authors found that immediate tmr at amputation reduced both phantom and residual limb pain on the nrs and may also reduce the formation of neuromas in the first place.24 traditional surgical excision has also been criticised in terms of the invasiveness of the dissection. a large and invasive dissection can lead to delayed wound healing as well as excessive adhesions and scar tissue formation, which can cause pain and discomfort during prosthesis fitting. this, in turn, can lead to delays in weight-bearing and rehabilitation, a large and invasive dissection of the neuroma can also be associated with higher recurrence rates.25 it is for these reasons that less invasive surgical excision techniques have been explored. thomas et al conducted a case series of 10 patients with limb amputation who underwent ultrasound-guided needle localisation of their painful neuroma prior to surgical excision. the authors found that pre-operative us-guided localisation of the neuroma facilitate less invasive surgical dissections and thus potentially a reduction in the aforementioned complications.25 limitations to our study include the relatively small sample size and lack of a control group, and thus prospective cohort studies with a larger sample size may be needed to confirm our results before it can be generalised to the larger population of individuals with limb amputation with residual limb neuroma. figure 6: us image of a bony spur (arrowed) adjacent to a 18x13mm neuroma along the sciatic nerve in a patient who had a transfemoral amputation (patient 7). conclusion our retrospective case series suggests that us-guided continuous rfa is a safe and effective treatment for residual limb neuroma associated pain and phantom pain in individuals with limb amputation. us-guided rfa can reduce pain and analgesic requirements, improve comfort and ease of wearing the prosthesis and reduce the potential need for surgical excision of the neuroma and its associated surgical risks. we recommend all patients undergo a diagnostic steroid injection prior to rfa to confirm that the residual limb neuroma is the source of the pain. further studies are needed to study the co-factors that could determine the residual limb pain and could affect the rfa treatment. this could facilitate a pre-selection of the responders to the treatment. we plan on conducting a prospective longitudinal series study with a larger sample size to investigate further the effect of rfa treatment of neuroma-associated residual limb and phantom pain in individuals with limb amputation including comparing different temperatures, durations, continuous versus pulsed rfa, as well as exploring combined rfa and phenol / alcohol injections (neurolysis). declaration of conflicting interests the authors declare no conflict of interest. sources of support the authors received no financial or other sources of support for this study. https://doi.org/10.33137/cpoj.v2i1.33061 https://jps.library.utoronto.ca/index.php/cpoj/index guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 8 continuous radiofrequency ablation of painful residual limb neuroma volume 2, issue 1, article no.4, november 2019 https://jps.library.utoronto.ca/index.php/cpoj/index author contribution dr henderson slater and dr mansour initially thought of the study. all three authors devised the study design. dr mansour devised the local protocol for rfa practice, collected pain scores up to 2 weeks post-treatment and the sonographic images. dr guo retrieved the clinical data from the patient notes, analysed and interpreted the data, and performed the statistical analysis. dr guo wrote and revised the 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surg. 2019;270(2):238–46. doi: 10.1097/sla.0000000000003088 24.valerio il, dumanian ga, jordan sw, mioton lm, bowen jb, west jm, et al. preemptive treatment of phantom and residual limb pain with targeted muscle reinnervation at the time of major limb amputation. j am coll surg. 2019;228(3):217–26. https://doi.org/10.1016/j.jamcollsurg.2018.12.015 25.thomas aj, bull mj, howard ac, saleh m. peri operative ultrasound guided needle localisation of amputation stump neuroma.injury.1999;30(10):689–91. https://doi.org/10.1016/s0020-1383(99)00185-0 https://doi.org/10.33137/cpoj.v2i1.33061 https://jps.library.utoronto.ca/index.php/cpoj/index guo s, mansour r, henderson slater d. ultrasound-guided continuous radiofrequency ablation of painful residual limb neuroma in individuals with limb amputationa retrospective case series. canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.4. https://doi.org/10.33137/cpoj.v2i1.33061 10 appendix mean ± standard deviation (sd) of pain scores at different time intervals preand post-rfa https://doi.org/10.33137/cpoj.v2i1.33061 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 2 2020 research article seth m, hou w, gyrates l.r, galassi j.p, limber e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i2.34609 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v3i2.34609 1 seth m, hou w, goyarts l.r, galassi j.p, lamberg e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i2.34609. research article effect of transtibial prosthesis mass on gait asymmetries seth m1*, hou w2, goyarts l.r1 , galassi j.p1, lamberg e.m1 1 school of health technology and management, stony brook university, stony brook, ny, usa. 2 school of medicine, stony brook university, stony brook, ny, usa. introduction individuals living with a transtibial amputation (tta) typically present with an asymmetrical gait pattern characterized by a prolonged stance phase (temporal asymmetry)1-5 and greater loading on the intact side as compared to the prosthetic side (limb loading asymmetry).5-8 a prolonged asymmetrical gait may predispose the individual to poor health outcomes, such as, knee or hip osteoarthritis of the intact side,8,9 back pain,10 and an increased risk of falling.11 further, walking with an asymmetrical gait pattern may attract unwanted attention towards the individual.12 while, inherent factors associated with a tta, such as weak prosthetic side push-off force 13 and issues pertaining to load bearing of the residual limb,14 may contribute to gait asymmetry, certain prosthetic factors, such as mass, may also contribute to gait asymmetry. currently, the impact of prosthesis mass on gait asymmetry is not well defined. further exploration may be vital to identifying any potential negative consequences that open access volume 3, issue 2, article no.5. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: individuals with transtibial amputation (tta) typically walk with an asymmetrical gait pattern, which may predispose them to secondary complications and increase risk of fall. gait asymmetry may be influenced by prosthesis mass. objective: to explore the effects of prosthesis mass on temporal and limb loading asymmetry in people with tta following seven days of acclimation and community use. methods: eight individuals with transtibial amputation participated. a counterbalanced repeated measures study, involving three sessions (each one week apart) was conducted, during which three load conditions were examined: no load, light load and heavy load. the light load and heavy load conditions were achieved by adding 30% and 50% of the mass difference between legs, at a proximal location on the prosthesis. kinematic and ground reaction force data was captured while walking one week after the added mass. symmetry indices between the prosthetic and intact side were computed for temporal (stance and swing time) and limb loading measures (vertical ground reaction force peak and impulse). findings: following seven days of acclimation, no significant differences were observed between the three mass conditions (no load, light load and heavy load) for temporal (stance time: p=0.61; swing time: p=0.13) and limb loading asymmetry (vertical ground reaction force peak: p=0.95; vertical ground reaction force impulse: p=0.55). conclusion: prosthesis mass increase at a proximal location did not increase temporal and limb loading asymmetry during walking in individuals with tta. hence, mass increase subsequent to replacing proximally located prosthesis components may not increase gait asymmetry, thereby allowing more flexibility to the clinician for component selection. article info received: july 16, 2020 accepted: october 12, 2020 published: october 19, 2020 citation seth m, hou w, goyarts l.r, galassi j.p, lamberg e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i 2.34609 keywords prosthesis, mass, gait, lower limb amputation, kinematics, kinetics, ground reaction forces, transtibial amputation, gait asymmetry. * corresponding author: mayank seth, phd delaware limb loss studies lab, university of delaware, newark, usa. e-mail: mseth@udel.edu orcid: https://orcid.org/0000-0003-3526-7058 https://doi.org/10.33137/cpoj.v3i2.34609 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i2.34609 https://doi.org/10.33137/cpoj.v3i2.34609 mailto:mseth@udel.edu https://orcid.org/0000-0003-2933-4365 https://orcid.org/0000-0003-2933-4365 2 seth m, hou w, goyarts l.r, galassi j.p, lamberg e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i2.34609. issn: 2561-987x effect of transtibial prosthesis mass on gait asymmetries seth et al. 2020 cpoj prosthesis mass may have on gait asymmetry and by extension health outcomes, of adults with tta. previous efforts to determine the relationship between prosthesis mass and gait asymmetry have been completed, but only with limited application. in one mathematical study, it was theorized that temporal asymmetry seen in the gait of adults with lower limb amputation may be minimized by the achievement of inertial symmetry between the intact and prosthetic side.15 other experimental and mathematical studies, however, found that matching prosthetic side mass completely (100%) with the intact side, through the addition of a distal load, produced an increase in temporal asymmetry.16-19 thus, suggesting that a prosthesis should not be as heavy as the segment it replaces, particularly if mass is distributed more distally. however, the experimental evidence is limited regarding smaller prosthesis mass increments (<100%) and the application of mass at proximal locations. this would result in a prosthesis heavier than its original weight, but lighter in comparison to the intact side. mass alterations at proximal locations are common clinically, subsequent to changing prosthesis components, i.e., socket, liner or socket/pylon interface adapters. hence, it is important to understand if these types of common increases in proximal prosthetic mass effect temporal asymmetry during walking. further, the relationship between prosthesis mass and limb loading in people with tta during walking has undergone limited exploration. using a single subject design hillary et al. examined the effects of increasing prosthesis mass by 0.53kg and 1.46kg on limb loading in an adult with tta.20 the increase in prosthesis mass resulted in higher limb loading forces (1st vertical ground reaction force peak) on both the prosthetic and intact side.20 these increased impact forces are concerning as they may have consequences for bone and joint health.8,9 increasing prosthesis mass, through proximal load application, will make a prosthesis heavier, but may not always make the prosthetic side as heavy as the intact side (or 100% matching). currently, it is unclear whether such mass increments to a prosthesis, i.e., less than 100% matching, will influence gait temporal and loading asymmetry of individuals with tta. further, the majority of current evidence on prosthesis mass is based on short acclimation periods prior to experimental data collection, which may yield differing results. the purpose of this study is to explore the effects of increasing prosthesis mass on temporal and limb loading asymmetry in people with tta following seven days of acclimation and community use. methodology a counterbalanced repeated measures study was conducted to examine the temporal and limb loading asymmetry in adults with tta under three load conditions: original prosthesis mass with no load added (no load; nl), original prosthesis mass with 30% of the mass difference between prosthetic and intact side added (light load; ll), and original prosthesis mass with 50% of the mass difference between prosthetic and intact side added (heavy load; hl). the choice of the mass conditions was based on a pilot unpublished retrospective analysis of 12 medical charts of individuals with tta. on an average, 30% (450g) and 50% (750g) of the mass difference between the prosthetic and intact side may represent the approximate mass change that may happen as a result of changing common prosthesis components. participants participants were included if they were male or female, between the ages of 18 to 70 years, had a unilateral amputation ≥ one year prior to participation and were community ambulators. further, to minimize potential effects due to recent changes in prosthesis or any components, only individuals using their current prosthesis for at least three months were included. potential participants were excluded if they had a health condition (cardiac, pulmonary, or musculoskeletal) limiting their ability to walk or if their prosthetic side was heavier than their intact side. based on previous literature on this topic,16,17,19 the study was planned to enroll a minimum of 6 individuals with tta. informed written consent was obtained before participation. the study was approved by stony brook university’s institutional review board. limb mass properties body mass (kg), height (m), residual limb and prosthesis measurements were ascertained. prosthetic side mass (psm) was calculated as the sum of prosthesis mass (with liner and shoe on a scale) and residual limb mass. to calculate residual limb mass, the residual limb was mathematically modeled as the frustum of a right circular cone using circumferential and length measurements as inputs and assuming a uniform tissue density of 1.1gm/cm3.21 in order to calculate intact side mass, body mass (bm) needed to be adjusted to account for the amputated limb segment17: equation 1: 𝐴𝐵𝑀 = 𝐵𝑀− 𝑃𝑆𝑀 (1−𝑐) where, bm is measured body mass while wearing the prosthesis, psm is prosthetic side mass, and c is the amount of mass accounted by an intact shank and foot (0.057 for men and 0.061 for women).17 then, using abm the intact side shank and foot mass was calculated from standard limb segment mass estimates (5.7% for men and 6.1% for women).22 in order to determine the load amount for each participant, the difference between prosthetic side and intact side mass was calculated and 30% (ll condition) and 50% (hl condition) of that difference was identified. https://doi.org/10.33137/cpoj.v3i2.34609 3 seth m, hou w, goyarts l.r, galassi j.p, lamberg e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i2.34609. issn: 2561-987x effect of transtibial prosthesis mass on gait asymmetries seth et al. 2020 cpoj research protocol participants attended three testing sessions scheduled one week apart (figure 1), during which the load conditions (nl, ll and hl) were examined. during session one, study purpose and procedures were explained and the mass difference between limbs was calculated. participants were then prepared for baseline data collection with their original prosthesis mass (nl). following nl data collection, prosthesis mass was altered by adding either 30% (ll) or 50% (hl) of the mass difference between limbs. mass was added circumferentially to the prosthesis socket at a proximal location that was 20 to 30% of the non-prosthetic side length. flexible car wheel balancing weights (bada steel tape-a-weight, hennessey industries llc, lavergne, tn, usa) were affixed at the desired location with one sided tape that was further held in place by wrapping coban (3m™, saint paul, mn, usa) to prevent any loosening or slippage. the load sequence was altered between participants such that half received hl then ll and half received ll then hl. once the mass was altered participants went home to use their prosthesis for seven days during their daily activities. figure 1: timeline of research sessions for one participant. the order of hl or ll was counterbalanced so that half received hl at session 1 then ll at session 2 and half received ll at session 1 then hl at session 2. nl= no load, ll= light load, hl= heavy load. data collection for all sessions, participants were prepared with the application of passive reflective markers over standardized anatomical landmarks on their pelvis and lower limbs using the modified hellen hayes marker set-up.23 on the prosthesis, markers were placed at locations corresponding to the intact side. participants walked at their comfortable walking speed over a 10m walkway, while kinematic data was captured using a ten camera vicon motion system® (oxford metrics, oxford, uk), recording at 100 hz. in addition, ground reaction force (grf) was captured through amti® force-plates (watertown, usa) recording at 1000hz. data analysis customized scripts developed in matlab® (mathworks, inc.), were used to analyze and process the temporal and grf data. gait events (heel strike and toe off) were identified from the raw marker data extracted from nexus vicon using the methodology proposed by zeni et al.24 temporal measures of stance time (heel strike to toe off) and swing time (toe off to heel strike) were determined for each leg. grf data was processed using a zero-lag low-pass 4th order butterworth filter, with a cutoff frequency of 20hz. the beginning and end of stance phase for the vertical component of grf (vgrf) was established using a vgrf threshold of 20n.25 the vgrf was normalized to each participant’s body mass (with prosthesis) and subsequently the maximum value during the 1st half of the stance phase was identified (vgrf peak) and the area under the curve throughout the entire stance phase was calculated (vgrf impulse). symmetry indices (si) for temporal and loading measures were calculated for each load condition26 where, i and p refer to intact and prosthetic side values. the si ranges between 0 and 1, where 0 represents perfect symmetry. a positive si indicates a higher value for the intact side: equation 2: 𝑆𝐼 = (𝐼−𝑃) (𝐼+𝑃)∗0.5 statistics a single-factor repeated measures analysis of variance (anova) was used to test for differences in si for stance time, swing time, vgrf peak and vgrf impulse among the nl, ll, and hl conditions. an alpha level of 0.05 was used to evaluate significance. results study sample eight male individuals with unilateral tta who ambulate without assistive devices participated in this study (table 1). overall, 19 inquiries were received, and 14 individuals were screened over the phone. of these 14, nine consented while five did not meet inclusion criteria or stated they did not want to add load to their device. of the nine consented, one was subsequently excluded because the prosthetic side mass was higher than the intact side mass. table 2 presents the mean of the calculated mass values. session 1 1) informed consent 2) limb mass difference calculated 3) baseline data collection with nl 4) prosthesis mass altered to hl session 2 1) data collection with hl 2) prosthesis mass altered to ll session 3 1) data collection with ll 2) prosthesis mass returned to nl 1-week acclimation 1-week acclimation https://doi.org/10.33137/cpoj.v3i2.34609 4 seth m, hou w, goyarts l.r, galassi j.p, lamberg e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i2.34609. issn: 2561-987x effect of transtibial prosthesis mass on gait asymmetries seth et al. 2020 cpoj table 1: participant demographics and clinical characteristics. participant age (yrs) body mass (kg)* height (m) time since amputation (yrs) amputation etiology side 01 48 85.0 1.88 6 infection left 02 29 101.0 1.72 4 neurofibromatosis left 03 50 113.1 1.86 1 trauma left 04 62 117.5 1.83 2 vascular right 05 26 95.0 1.84 14 cancer left 06 57 91.6 1.81 7 trauma left 07 30 75.0 1.79 30 congenital right 08 59 88.5 1.76 59 congenital right mean (sd) 45.1 (14.7) 95.8 (14.2) 1.81 (0.05) 15.4 (20) * body mass was measured with the prosthesis and shoe on the participant. table 2: estimated mass properties of the prosthetic and intact side. measure mean (sd) range adjusted body mass 96.9 (14.8) 75.4 – 119.5 non-prosthetic side mass 5.5 (0.8) 5.3 – 6.8 prosthetic side mass 4.5 (0.4) 3.9 – 5.2 mass difference between sides 1.0 (0.7) 0.4 – 2.3 load conditions light load (30% of difference) 0.3 (0.2) 0.1 – 0.7 heavy load (50% of difference) 0.5 (0.3) 0.2 – 1.1 all values in kg. non-prosthetic side mass refers to estimated shank and foot mass of non-prosthetic side. prosthetic side mass refers to the sum of estimated residual limb mass and prosthesis mass (with shoe, liner and suspension system). main results the mean (sd) for stance time, swing time, vgrf peak and vgrf impulse on the prosthetic and intact side with the three load conditions (nl, ll and hl) and the si are presented in table 3. the mean (sd) stance time si and swing time si for the three load conditions is also presented in figure 2. the mean vgrf profile of the participants for the prosthetic and intact side with the three load conditions (nl, ll and hl) is presented in figure 3. following seven days of acclimation, increasing the mass of the prosthesis by 30% and 50% did not significantly affect the si values between the prosthetic and intact side for temporal (stance time: p=0.61; swing time: p=0.13) and loading measures (vgrf peak: p=0.95; vgrf impulse: p=0.55). figure 2: mean stance time si (a) and swing time si (b) across the three load conditions. error bars represent 1 sd. negative si values indicate that intact side values were higher. nl= no load, ll= light load, hl= heavy load. table 3: mean (sd) temporal and grf measures for the three load conditions. nl= no load, ll= light load, hl= heavy load. nl ll hl sig. (p-value) p np si% p np si% p np si% stance time (secs) 0.77 (0.04) 0.80 (0.05) 3.49% (3.79) 0.79 (0.04) 0.80 (0.05) 2.15% (2.77) 0.76 (0.05) 0.78 (0.05) 2.69% (2.23) 0.61 swing time (secs) 0.40 (0.03) 0.39 (0.02) -3.32% (5.23) 0.41 (0.01) 0.39 (0.02) -4.46% (5.16) 0.40 (0.02) 0.39 (0.02) -1.91% (5.86) 0.13 vgrf peak (bm) 1.03 (0.07) 1.14 (0.12) 9.70% (10.70) 1.05 (0.07) 1.15 (0.07) 9.06% (6.20) 1.06 (0.08) 1.16 (0.09) 9.51% (9.35) 0.95 vgrf impulse (bm) 0.56 (0.04) 0.60 (0.04) 7.99% (7.11) 0.57 (0.03) 0.61 (0.04) 6.89% (6.32) 0.56 (0.04) 0.60 (0.03) 6.73% (7.53) 0.55 p: mean (sd) raw score for the prosthetic side; np: mean (sd) raw score for the non-prosthetic side; si%: symmetry index % between the prosthetic and nonprosthetic side; bm: normalized to body mass. the p-values between the three load conditions are for the si% 3.49% 2.15% 2.69% 0% 2% 4% 6% 8% nl ll hl stance time sia -3.32% -4.46% -1.91% -11% -7% -3% nl ll hl swing time si b https://doi.org/10.33137/cpoj.v3i2.34609 5 seth m, hou w, goyarts l.r, galassi j.p, lamberg e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i2.34609. issn: 2561-987x effect of transtibial prosthesis mass on gait asymmetries seth et al. 2020 cpoj figure 3: mean normalized vgrf activity of the prosthetic (a) and intact side (b) across the three load conditions (nl, ll and hl). the shaded region represents 1±sd of the group mean27 for that load condition. nl= no load, ll= light load, hl= heavy load. discussion this study explored the impact of increasing prosthesis mass on temporal and limb loading asymmetry in people with tta following seven days of acclimation and community use. according to the findings, increasing prosthesis mass by either 30% or 50% of the mass difference between legs did not significantly alter temporal and limb loading asymmetry. these findings imply that a range of prosthesis mass may exist for this population. this ultimately may allow clinicians flexibility when choosing prosthesis components knowing that increasing mass within this range may not negatively impact gait asymmetries. temporal asymmetry literature on transtibial prosthesis mass has largely focused on examining temporal asymmetry during walking.15-19 perhaps the proposed association between limb inertia and swing time or the secondary complications as a result of an asymmetrical gait, necessitate the examination of temporal measures following mass alterations. in this study, stance and swing time asymmetries were not significantly affected as a result of the mass alteration. previous studies examining stance and swing time asymmetries have found that matching prosthetic side mass to the intact side (100% load condition) increases asymmetry.16-19 the same however, is not true for partial matching (50% load condition). similar to the findings of the current study, smith and martin report no effect of the 50% load condition on stance and swing time asymmetry.17 however, mattes et al. observed a significant increase in temporal asymmetry with the 50% load condition.16 hence, mattes et al., observed a linear response to the mass increase; as prosthesis mass increased, stance time on the intact side and swing time on the prosthetic side increased, thereby increasing limb temporal asymmetry.16 interestingly, mattes et al., used a similar approach as the current study to estimate mass difference between limbs. however, they achieved the 50% condition by adding an average load of 0.85kgs,16 while this study used an average of 0.54kgs, which may partially explain the divergence in findings. perhaps the key difference between the studies is the length of acclimation period used, ten minutes by mattes et al.,16 versus one week in this study. the longer acclimation time provided in this study may have allowed participants to stabilize their gait, leading to the lack of statistically significant findings. although, in previous research it has been observed that stance and swing time asymmetries (as a result of the 100% load condition) persisted even after eight days of acclimation19; this finding, doesn’t necessarily rule out the importance of acclimation. it is more likely that individuals with tta are not well suited to carry a prosthesis that weighs as much as the amputated segment. limb loading asymmetry limb loading asymmetry (measured using vgrf peak and vgrf impulse si), was not affected as a result of the mass increase, i.e., no differences were observed between the three load conditions (nl, ll and hl). the positive si values (table 3) indicate that participants in this study loaded their intact side more than the prosthetic side, consistent with previous findings in the literature.5-8 the addition of load, however, did not significantly change the proportion of loading experienced by the intact side. prosthetic side % gait cycle intact side n o rm a li z e d v g r f n o rm a li z e d v g r f % gait cycle https://doi.org/10.33137/cpoj.v3i2.34609 6 seth m, hou w, goyarts l.r, galassi j.p, lamberg e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i2.34609. issn: 2561-987x effect of transtibial prosthesis mass on gait asymmetries seth et al. 2020 cpoj in the single subject case study by hillery et al., the authors observed an increase in loading (vgrf peak) on the prosthetic and the intact side with an increase in prosthesis mass.20 based on the si equation,26 it appears that the study participant’s loading asymmetry increased from 5.4% at baseline to 12% with the intermediate load (0.5kgs) and 21% with the heaviest load (1.5kgs).20 in contrast, vgrf peak si in the current study changed from an average of 9.70% at baseline to 9.1% with ll (0.3kgs) and 9.5% with the heaviest load condition, hl (0.5kg). this difference in findings may be due to the heavier loads used by hillery et al., or perhaps the longer acclimation period given in the current study allowed users to stabilize their gait before data was collected. however, given the single-subject study design by hillery et al., their findings may not be generalized to a larger group.20 in a more recent study of a group of active adults with tta (n=10), alcantara et al. examined the impact of increasing the mass of a running-specific prosthesis and biological foot on participants’ limb loading asymmetry during running.28 prosthesis and biological foot mass were increased by adding 100g or 300g at the toe region. the mass increase, however, did not result in any significant change to limb loading asymmetry (vgrf peak si or average-stance vgrf si) as compared to baseline, regardless of added load (100g or 300g) or whether mass was added to the prosthesis or both limbs.28 obvious differences exist between alcantara et al., and the current study, such as the location of mass addition or their use of a running task. however, collectively, these findings suggest that small increases in prosthesis mass may not contribute to the limb loading asymmetry and by extension lower health outcomes generally associated with asymmetrical limb loading, such as knee or hip osteoarthritis of the intact side. the need to change a prosthesis component or replace a prosthesis completely may arise due to various personal and/or clinical reasons. such changes may increase or decrease the overall prosthesis mass. for example, the replacement of prefabricated transtibial gel liners, which range from 202g to 722g, may alter prosthesis mass.29 findings from this study suggest that the mass increments similar to those observed after replacing proximally located prosthesis components (such as, the socket, liners, or socket/pylon interface adapters), may not increase gait asymmetry. these findings are clinically relevant as they may serve as a guide for clinicians when routinely adjusting prosthesis mass. however, to further identify the impact of prosthesis mass on gait asymmetry, it is vital that future large-scale studies explore the impact of various commercially available prosthesis components and related functional and clinical outcomes. moreover, future studies may consider controlling other factors that may influence gait characteristics of an individual, for example, residual limb length, quality and type of suspension between the prosthesis and residual limb, or exertion of the individual during a walking task. study limitations the current study was limited both by a small sample size (n=8), and a male-only participant group. it is possible that the small sample size may not have had sufficient power to detect a significant change. moreover, in order to make stronger conclusions on prosthesis mass, it remains necessary to evaluate both men and women with tta. as part of the inclusion criteria, only individuals that were capable of independent ambulation were included within the study. therefore, the current findings may not extend to individuals with tta who exhibit lower levels of activity. further, this study chose to limit mass increase to 50% of the mass difference between both limbs. to establish the upper limit of a ttp mass it may be necessary to evaluate heavier loads. lastly, certain covariates, such as, residual limb length, quality and type of suspension between the prosthesis and residual limb or prosthesis componentry may have impacted both gait asymmetry and prosthesis mass of the study participants but were not controlled in this study. conclusion temporal and loading asymmetries during walking in people with tta may lead to secondary complications of the intact side and increase risk of falls. currently, it is unclear if prosthesis mass alterations that may occur during routine clinical visits will impact these gait asymmetries. this exploratory study observed that following seven days of use increases in proximally distributed prosthesis mass (up to 50% of the mass difference between legs), did not further increase temporal and limb loading asymmetry of individuals with tta, thereby allowing more flexibility to the clinician for component selection. confirmation of findings with large-scale studies may help identify the impact of prosthesis mass on gait asymmetry. acknowledgements we would like to acknowledge study participants for their contribution towards this research study. declaration of conflicting interests the authors have no conflicts of interests to declare. author contribution mayank seth: study conceptualization, analysis, data collection, data interpretation and writing original draft wei hou: assisted in study design, led statistical analysis, writing review & editing https://doi.org/10.33137/cpoj.v3i2.34609 7 seth m, hou w, goyarts l.r, galassi j.p, lamberg e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i2.34609. issn: 2561-987x effect of transtibial prosthesis mass on gait asymmetries seth et al. 2020 cpoj laura r goyarts: assisted in data collection, writing review & editing james p galassi: assisted in data collection, writing review & editing eric m lamberg: study conceptualization, project administration, supervision, data interpretation, writing – review & editing sources of support this research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors. ethical approval the study was approved by stony brook university’s institutional review board. references 1.dingwell jb, davis bl, frazier dm. use of an instrumented treadmill for real-time gait symmetry evaluation and feedback in normal and trans-tibial amputee subjects. prosthet orthot int. 1996;20(2):101-10. doi: 10.3109/03093649609164426 2.nolan l, lees a. the functional demands on the intact limb during walking for active transfemoral and transtibial amputees. prosthet orthot int. 2000;24(2):117-25. doi: 10.1080/03093640008726534 3.nolan l, wit a, dudzinski k, lees a, lake m, wychowanski m. adjustments in gait symmetry with walking speed in trans-femoral and trans-tibial amputees. gait posture. 2003;17(2):142-51. doi: 10.1016/s0966-6362(02)00066-8 4.sanderson dj, martin pe. lower extremity kinematic and kinetic adaptations in unilateral below-knee amputees during walking. gait posture. 1997;6(2):126-36. doi:10.1016/s0966-6362(97)01112-0 5.cutti ag, verni g, migliore gl, amoresano a, raggi m. reference values for gait temporal and loading symmetry of lowerlimb amputees can help in refocusing rehabilitation targets. j neuroeng rehabil. 2018;15(1):61. doi: 10.1186/s12984-0180403-x 6.engsberg j, lee a, tedford k, harder j. normative ground reaction force data for able-bodied and trans-tibial amputee children during running. prosthet orthot int. 1993;17(2):83-9. doi: 10.3109/03093649309164361 7.powers cm, torburn l, perry j, ayyappa e. influence of prosthetic foot design on sound limb loading in adults with unilateral below-knee amputations. arch phys med rehabil. 1994;75(7):8259. doi: 10.1016/0003-9993(94)90146-5 8.gailey r, allen k, castles j, kucharik j, roeder m. review of secondary physical conditions associated with lower-limb amputation and long-term prosthesis use. j. rehabil. res. dev. 2008;45(1). doi: 10.1682/jrrd.2006.11.0147 9.kulkarni j, adams j, thomas e, silman a. association between amputation, arthritis and osteopenia in british male war veterans with major lower limb amputations. clin rehabil. 1998;12(4):34853. doi: 10.1191/026921598672393611 10.esposito er, wilken jm. the relationship between pelvis–trunk coordination and low back pain in individuals with transfemoral amputations. gait posture. 2014;40(4):640-6. doi: 10.1016/ j.gaitpost.2014.07.019 11.vanicek n, strike s, mcnaughton l, polman r. gait patterns in transtibial amputee fallers vs. non-fallers: biomechanical differences during level walking. gait posture. 2009;29(3):415-20. doi: 10.1016/j.gaitpost.2008.10.062 12.handžić i, reed kb. perception of gait patterns that deviate from normal and symmetric biped locomotion. front. psychol. 2015;6:199. doi: 10.3389/fpsyg.2015.00199 13.adamczyk pg, kuo ad. mechanisms of gait asymmetry due to push-off deficiency in unilateral amputees. ieee trans neural syst rehabil eng. 2015;23(5):776-85. doi: 10.1109/tnsre. 2014.2356722 14.silver-thorn b, steege jw, childress ds. a review of prosthetic interface stress investigations. j. rehabil. res. dev. 1996. 15.mena d, mansour j, simon s. analysis and synthesis of human swing leg motion during gait and its clinical applications. j biomech. 1981;14(12):823-32doi:10.1016/0021-9290(81)90010-5 16.mattes sj, martin pe, royer td. walking symmetry and energy cost in persons with unilateral transtibial amputations: matching prosthetic and intact limb inertial properties. arch phys med rehabil. 2000;81(5):561-8. doi: 10.1016/s0003-9993(00)90035-2 17.smith jd, martin pe. effects of prosthetic mass distribution on metabolic costs and walking symmetry. j appl biomech. 2013;29(3):317-28. doi: 10.1123/jab.29.3.317 18.selles rw, korteland s, van soest a, bussmann jb, stam hj. lower-leg inertial properties in transtibial amputees and control subjects and their influence on the swing phase during gait. arch phys med rehabil. 2003;84(4):569-77. doi: 10.1053/apmr. 2003.50037 19.smith jd, martin pe. short and longer term changes in amputee walking patterns due to increased prosthesis inertia. j prosthet orthot. 2011;23(3):114-23. doi: 10.1097/jpo.0b013e3182248d90 20.hillery s, wallace e, mcilhagger r, watson p. the effect of changing the inertia of a trans-tibial dynamic elastic response prosthesis on the kinematics and ground reaction force patterns. prosthet orthot int. 1997;21(2):114-23. doi: 10.3109/ 03093649709164539 21.hanavan el. a mathematical model of the human body. amrltr-64-102, ad-608-463. ohio: aerospace medical research laboratory, wright-patterson air force base. 1964. 22.de leva p. adjustments to zatsiorsky-seluyanov's segment inertia parameters. j biomech. 1996;29(9):1223-30. doi:10.1016/ 0021-9290(95)00178-6 23.kadaba mp, ramakrishnan hk, wootten me. measurement of lower extremity kinematics during level walking. j orthop res. 1990;8(3):383-92. doi: 10.1002/jor.1100080310 24.zeni jr j, richards j, higginson j. two simple methods for determining gait events during treadmill and overground walking using kinematic data. gait posture. 2008;27(4):710-4. doi: 10.1016/j.gaitpost.2007.07.007 25.rueda fm, diego ima, sánchez am, tejada mc, montero fmr, page jcm. knee and hip internal moments and upper-body kinematics in the frontal plane in unilateral transtibial amputees. gait posture. 2013;37(3):436-9. doi: 10.1016/j.gaitpost.2012. 08.019 https://doi.org/10.33137/cpoj.v3i2.34609 8 seth m, hou w, goyarts l.r, galassi j.p, lamberg e.m. effect of transtibial prosthesis mass on gait asymmetries. canadian prosthetics & orthotics journal. 2020;volume 3, issue 2, no.5. https://doi.org/10.33137/cpoj.v3i2.34609. issn: 2561-987x effect of transtibial prosthesis mass on gait asymmetries seth et al. 2020 cpoj 26.robinson ro, herzog w, nigg bm. use of force platform variables to quantify the effects of chiropractic manipulation on gait symmetry. j manipulative physiol ther. 1987;10(4):172-6. 27.musall s. stdshade matlab central file exchange 2010 available from: https://www.mathworks.com/matlabcentral/ fileexchange/29534-stdshade. 28.alcantara rs, beck on, grabowski am. added lower limb mass does not affect biomechanical asymmetry but increases metabolic power in runners with a unilateral transtibial amputation. eur j appl physiol. 2020;120(6):1449-56. doi: 10.1007/s00421-020-04367-9 29. selinger d. weight of prefabricated transtibial gel prosthetic liners a standardized sample. resident research project. california state university, dominguez hills. 2004. https://doi.org/10.33137/cpoj.v3i2.34609 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.36366 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 stakeholder perspectives a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant guirao l1, samitier b1, frossard l2-5* 1 servicio de rehabilitaión hospital asepeyo sant cugat, barcelona, spain. 2 yourresearchproject pty ltd, brisbane, australia. 3 griffith university, gold coast, australia. 4 university of the sunshine coast, maroochydore, australia. 5 queensland university of technology, brisbane, australia. introduction importance of preliminary cua of innovation developers of new prosthetic care solutions must demonstrate the safety, efficacy, and socio-economic benefits of their innovations.1-14 value for money of a prosthetic care innovation is usually evidenced during a health technology assessment (hta) and a health economic evaluation (hee).14-17 providing timely evidence is critical for the clinical promotion of an innovation. ijzerman and steuten (2011) highlighted that an early, preliminary, and full cost-utility analysis (cua) can be performed at the early, middle, and late stages of clinical acceptance of any medical treatment, respectively.[6] kannenberg and seidinger (2019) suggested that these three types of cuas should be undertaken by manufacturers of prosthetic solutions at the early, middle, and late phases of development.7 in frossard (2021), we noted the consensus around the weaknesses of full cuas (e.g., lack of timeliness, resource open access volume 4, issue 2, article no.11. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract several obstacles must be overcome before preliminary cost-utility analyses (cua) of prosthetic care innovations can be routinely performed. the basic framework of preliminary cuas and handson recommendations suggested previously might contribute to wider adoption. however, a practical application for an emerging intervention is needed to showcase the capacity of this proposed preliminary cua framework. this study presented the outcomes of preliminary cua of the distal weight bearing keep walking implant (kwi), an emerging prosthetic care innovation that may reduce socket fittings for individuals with transfemoral amputation. the preliminary cuas compared the provision of prosthetic care without (usual intervention) and with the kwi (new intervention) using a 15-step iterative process focused on feasibility, constructs, analysis, and interpretations of outcomes from an australia government prosthetic care perspective over a six-year time horizon. baseline and incremental costs were extracted from schedules of allowable expenses. baseline utilities were extracted from a study and converted into quality-adjusted life-year (qaly). incremental utilities were calculated based on sensible gains of qaly from baselines. the provision of the prosthetic care with the kwi could generate an indicative incremental cost-utility ratio (icur) of -$36,890 per qaly, which was $76,890 per qaly below willingness-to-pay threshold, provided that the kwi reduces costs by $17,910 while increasing utility by 0.485 qaly compared to usual interventions. this preliminary cua provided administrators of healthcare organizations in australia and elsewhere with prerequisite evidence justifying further access to market and clinical introduction of the kwi. altogether, this work suggests that the basic framework of the preliminary cua of a prosthetic care innovation proposed previously is feasible and informative when a series of assumptions are carefully considered. this study further confirms that preliminary cuas prosthetic care interventions might be a relevant alternative to full cua for other medical treatments. citation guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 keywords artificial limbs, bone-anchored prosthesis, cost-effectiveness, costutility, distal weight bearing implant, osseointegration, prosthesis * corresponding author laurent frossard (phd), professor of bionics, yourresearchproject pty ltd, brisbane, australia. e-mail: laurentfrossard@outlook.com orcid number: https://orcid.org/0000-0002-0248-9589 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.36366 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.36366 mailto:laurentfrossard@outlook.com https://orcid.org/0000-0002-0248-9589 2 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e intensive) and strengths of earlier cuas (e.g., identify evidence gaps and headroom for improvement, educate full cua, fast track approval).13 concepts of preliminary cuas are emerging.[6] however, several obstacles must be overcome before these analyses are routinely performed.12 among others, disparities of methods and high uncertainty make the outcomes of usual preliminary cuas challenging to interpret, appraise, and share.6,13,18 in frossard (2021), we suggested that these shortcomings could be alleviated by a basic framework of preliminary cuas, given the already existing standardization of prosthetic care (e.g., list of tasks, timeline of intervention).18 consequently, we put together a basic framework considering fundamentals and applied principles of health economics as well as recent preliminary cuas of transfemoral and transtibial bone-anchored prostheses.19,20 previously, frossard (2021) created a 15-step iterative process including hands-on recommendations that focuses on feasibility, constructs, analysis, and interpretations of outcomes. furthermore, the proposed preliminary cuas could be facilitated when considering abided constructs, prior schedules of expenses and benchmark of baseline, and incremental utilities.18 it was anticipated that this new approach to preliminary cua could simplify the selection of methods, standardize outcomes, ease comparisons between innovations, and streamline pathways for adoption. however, a practical application for an emerging intervention is required to illustrate and further advance the validation of the proposed basic framework. case of keep walking implant an example of emerging intervention is the distal weight bearing keep walking implant (kwi, tequir s. l., spain). the kwi involves the surgical insertion of an endomedullar implant including an osseointegrated femoral stem and a rounded spacer into the distal end of residual femur (figure 1). the treatment is indicated for a broad range of case-mix with transfemoral amputation (tfa) due to vascular, trauma, and tumor issues among patients who experience substantial challenges with socket fittings, including nonprosthetic users.10 this surgical procedure has been performed gradually on more than 75 cases over the last few years, mainly in europe and a few other countries. preliminary outcomes from ongoing clinical trials suggested that the kwi could potentially ease socket fittings (e.g., reshaping residuum, restore distal weight bearing capability on the femur).21 stronger evidence will be required. meanwhile, kwi could be reasonably considered as candidate intervention to reduce socket fittings. figure 1: example of implantation of the distal weight bearing keep walking implant in the transfemoral residuum (a) including and endomedullar femoral stem (b) and rounded spacer (c) that reshaping the distal end of the residuum with a more uniform cone facilitating direct transmission of loading and, altogether, improving safely quality of life and walking ability. 22-25 needs and challenges the population of individuals suffering from limb loss due to vascular diseases is projected to grow at an unprecedented pace in the next decade worldwide.26 there are undeniable market opportunities for solutions, such as the kwi, that can facilitate access to prosthetic fittings for this population. however, evidence of health economics benefits of other interface technologies reducing socket fittings is sparse.27-29 list of abbreviations bap: bone-anchored prostheses bmi: body mass index cua: cost-utility analysis icer: incremental cost-effectiveness ratio icur: incremental cost-utility ratio k1: individuals classified in level 1 of medicare functional classification k2: individuals classified in level 2 of medicare functional classification k3: individuals classified in level 3 of medicare functional classification k4: individuals classified in level 4 of medicare functional classification k-level: medicare functional classification level k0: individuals classified in level 0 of medicare functional classification kwi: distal weight bearing keep walking implant l-code: procedure extracted from us healthcare common procedure coding system qaly: quality-adjusted life-year sf36: 36-item short form survey wtp: willingness-to-pay threshold a c b https://doi.org/10.33137/cpoj.v4i2.36366 3 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e clearly, the kwi is at a stage of development when preliminary evidence of its cost-utility would be most timely and beneficial. preliminary cua of the kwi will be particularly appealing for decision-makers involved in advisory committees of governing bodies and healthcare organizations inclined or already familiar with osseointegrated solutions, such as australia.8-12,18-20,30-35 however, any preliminary cua of the kwi will have to work around the typical sparsity of clinical outcomes collected essentially with a small cohort in a single jurisdiction that is likely to be outside the investigators’ own healthcare organization. purposes the primary purpose of this study was to put the basic framework of preliminary cua suggested previously to the test with an emerging prosthetic care innovation that could reduce socket fittings for tfas.13,18 the secondary purposes were to: a. compare icurs for the provision of transfemoral prostheses fitted to a residuum without (usual treatment) and with the kwi (new treatment) over a mid-term time horizon from an australian government prosthetic care perspective. b. establish if the outcomes of this preliminary cua could be deemed favorable enough to promote further clinical introduction of the kwi in australia and elsewhere. c. produce basic information needed to facilitate subsequent primary and modeling cuas of the kwi (e.g., within-trial horizon studies). the specific objectives were to: 1) determine the feasibility of this preliminary cua, including the evaluation of early evidence of safety and efficacy of the kwi. 2) outline constructs of this preliminary cua, including the educated choices made to determine the perspective, time horizon, and various scenarios (e.g., worse-case, best-case, and base-case). 3) conduct analysis, including icurs based on estimation of baseline and incremental costs (e.g., schedules of allowable expenses), and utilities (e.g., calculation of retrospective health-related quality of life data, assumption of sensible gains). 4) interpret outcomes considering the limitations and comparisons with willingness-to-pay threshold (wtp) and other socket-free interventions leading to the outline of an implementation strategy. supplementary material will be published in data in brief, including a list of scenarios, a breakdown of allowable hours for labor, components with and without the kwi for all klevels, mapping of 36-item short form survey (sf36) data into qaly, and a comparison with other socket-suspended and socket-free cost-utility studies as well as the consolidated health economic evaluation reporting standards (cheers) and the consensus health economic criteria (chec) extended checklists.36-38 setting we purposely chose to perform this preliminary cua from the perspective of an australian healthcare organization. being well acquainted with bap solutions, australian state governments have already performed horizon scans for socket-free technologies including direct skeletal attachments that have selected the kwi.12,19,30,35 this choice of setting could be challenging. indeed, gallego et al. (2011) highlighted that the assessment of new medical devices and medical technologies prior to introduction is very difficult because of the complexity of the australian healthcare system.39 however, this preliminary cua could be facilitated by considering the same setting that we presented in frossard et al. (2018, 2020).19,20 practically, we performed this preliminary cua from the perspective of an australian state government minister of health with a yearly budget of $5 million, servicing 4,000 consumers annually through a network of up to ten prosthetists (e.g., queensland artificial limb service).12,30,31 determine feasibility as explained in frossard (2021), this feasibility phase was organized around a three-step waterfall process with decision point at every step.18 investigate product (step 1a) unlike other interventions relying on direct skeletal attachment of prosthetic limb, the kwi has no percutaneous part protruding from the skin that creates a permanent open stoma. the prosthesis is attached through a socket. interestingly, the implant could lengthen the femoral condyle by a few centimeters depending on the bone and soft tissues conditions. the spacer restores the distal weight bearing capability on the femur, similar to a knee disarticulation.21 thus, the kwi could reshape the distal end of the residuum with a more uniform and consistent cone shape that could ease socket fittings.40-42 all things considered, the product investigation suggested that the benefits of the kwi could be possibly translated into a reduction of socket fittings for a large population of tfas (e.g., vascular, trauma, tumor). we found the information satisfactory to warrant further searches for evidence of safety. https://doi.org/10.33137/cpoj.v4i2.36366 4 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e search for evidence of safety (step 1b) preliminary evidence of stability of kwi is presented in table 1a.24 a recent cohort study (n=13) showed that the mean percentage of bone mineral density of the amputated limb in comparison with the sound limb was 70.6% preimplantation and 73.2% 14 months post-implantation, with an average increase of 2.6%.24 this study suggested that femoral stem not only osseointegrates over time but also could increase cortical thickness around the implant.43,44 long-term cohort studies currently being conducted will confirm to what extent this increase of stability impacts risks of loosening, periprosthetic fractures, and infections while revealing incidence of breakage of implant parts and the overall rate of implant removal. in the meantime, van eck and mcgough (2015) showed that the infection rate of osseointegrated implants relying on a percutaneous part ranged from 2% to 41%.45,46 in principle, the risk of infections with the kwi should be significantly lower than these osseointegrated solutions. the absence of stoma limits continuous exposure to the environment and subsequent risks of infection. rate of infection should be comparable to hip or knee replacement procedures, that is roughly about 1%. regardless of evidence gaps in adverse events, we found sufficient indications that the kwi has the capacity to provide a safe prosthetic osseointegrated attachment solution to search for the evidence of efficacy. search for evidence of efficacy (step 1c) evidence of efficacy of kwi for cohort studies conducted during clinical trials is summarized in table 1b.22,23,25 preliminary studies indicated that the use of the prosthesis with the kwi increased significantly from 10.70 to 12.87 hours per day. the self-administered houghton scale score, reflecting a person’s perception of prosthetic use, also increased from 9.65 to 9.78. the self-administered locomotor capabilities index score, assessing overall locomotor abilities, increased from 38.04 to 38.95. studies showed the efficacy of the kwi to restore walking ability.23,25 studies reported a significant increase in gait speed from 0.86±0.29 m/s to 1.06±0.32 m/s as well as distance walked from 103.6±34.7 m to 128±38.9 m during a two-minute walk test conducted 14 months after implantation.23,25 the physiological cost index, representing energetic efficiency of walking, showed no significant difference without and with the kwi.25 guirao et al. (2018) used the 36-item short form survey (sf36) to show improvement in quality-of-life with the kwi.22 participants reported that the treatment led to improvement in each health domain score, including an increase of 3.94±9.22 and 1.14±8.07 for the summary physical and mental health components, respectively.22 further evidence comparing patient’s experience with prosthetic use and socket fittings using surveys like the orthotics and prosthetics user's survey (opus), the quebec user evaluation of satisfaction with assistive technology (quest 2.0), and the socket comfort score (scs) without and with the kwi is needed. however, one could argue that outcomes presented above could be surrogate indicators of socket comfort. therefore, these results suggested that kwi might contribute to increase overall socket comfort. despite of these knowledge gaps, we believe that the outcomes showing efficacy of the kwi solution currently available were adequate to justify completing the rest of the preliminary cua. table 1: summary of clinical outcomes with and without keep walking implant (kwi). early evidence of clinical outcomes without kwi (before treatment) with kwi (after treatment) a-safety stability percentage of bone mineral density* 24 70.6% 73.2% b-efficacy prosthetic use daily use 10.7 hr/day 12.9 hr/day houghton scale score 9.7 9. 8 lci score 38.0 39.0 mobility gait speed 23,25 0.9±0.3m/s 1.1±0.3m/s 2 mwt 23,25 103.6±34.7m 128±38.9m pci 25 0.57±0.3 0.51±0.2 health-related quality of life sf36-physical functioning 22 39.0±10.1 45.8±8.1 sf36-role physical 22 51.9±9.0 54.1±3.9 sf36-bodily pain 22 51.1±11.8 53.3±8.1 sf36-general health 22 51.3±10.1 52.4±9.8 * bone mineral density of the amputated limb expressed as a percentage with the sound limb; lci: locomotor capabilities index; 2 mwt: 2-minute walk test; pci: physiological cost index; sf36: 36-item short form survey. outline constructs this five-step phase entailed choosing the list of parameters framing this preliminary cua. define perspective (step 2a) a cua from government healthcare perspective could be achieved when primary, secondary, and tertiary services of a healthcare organization are centralized and interconnected enough to produce analytics and report whole care costs.47,48 however, like many other systems worldwide, the structure of australian state healthcare https://doi.org/10.33137/cpoj.v4i2.36366 5 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e organizations is siloed.39 each service manages its own resources often independently of other services. whether implantation of kwi increases or reduces ongoing medical costs has little relevance to administrators of prosthetic care services.10,19,20 rather, they would be more interested in knowing if the alleged capacity of the kwi to reduce socket fittings could contribute to alleviating some of the prosthetic care financial burden.10-12 therefore, conducting a preliminary cua of the kwi from the australian government prosthetic care perspective, as were recently published studies examining prosthetic direct skeletal attachments, would be a relevant starting point.19,20 define the time horizon (step 2b) some studies suggested that a rather short time horizon would be indicated for the preliminary cua for the kwi.14,47,49-55 because of the prosthetic care perspective, the time horizon should be primarily determined by realistic estimations of the costs for the fitting of the sockets as well as knee and foot units. therefore, we chose a six-year time horizon that corresponded to a funding cycle allowing the replacement of knee and foot/ankle units at the end of their respective three and two-year expected lifespans.19,20,56 we assumed that estimations of components costs beyond this time horizon were likely to be grossly inaccurate. as detailed below, we considered that tfas fitted without and with the kwi would experience steady utilities over this time horizon. identify scenarios (step 2c) in principle, progressions across the five medicare functional k-levels (k0–k4) for up to 15 scenarios could considered, as detailed in the supplementary material.18 however, instead, we purposely investigated only the five scenarios we deemed the most realistic and likely to represent expected clinical outcomes with the kwi as described in figure 2.22-25 worse-case, best-case, and base-case scenarios corresponding to scenarios 1, 3, and 5 were created assuming no progression for k1, as well as progression from k1 to k3 and k2 to k3 without and with the kwi, respectively. set discount (step 2d) the six-year time horizon was short enough to predict costs of provision of prosthetic fittings (e.g., labor, parts). the most important costs would be incurred at the beginning of the cycle. finally, we assumed that utilities would remain consistent across the time horizon. consequently, no costs and utilities were discounted. assess uncertainty (step 2e) here, the key events were the socket fittings that we purposely reduced to one per annum with the kwi, as justified in step 3b. we considered that comparisons of cost reduction going from four or less to one socket fitting yearly were deemed beyond the scope of this preliminary cua. nonetheless, impact of socket fittings frequency could be easily achieved given the readability and scalability of the raw data presented here and in the supplementary material. alternatively, the sensibility analysis was limited to the extraction of basic descriptive statistics (e.g., mean, standard deviation, lower and upper 95% confidence intervals, minimum, maximum, and range) for the costs, utilities, and icurs aggregated across the scenarios. conduct analysis this four-step phase estimates costs, utilities, and icurs for all selected scenarios. estimate costs (step 3a) primary post-treatment costs for the provision of prosthetic care with the kwi are not yet available in australia. alternatively, typical expenses for the provision of prosthetic care without and with the kwi were extracted from two schedules detailing allowable expenses for labor and parts (table 2 and table 3). the type and frequency of intervention were recommended by two qualified and experienced australian prosthetists, taking into consideration the best practices for prosthetic care with the kwi and lifetime of components. the actual dollar value of an individual item was based on recently published schedules of allowable expenses for lower limb bap as well as prices recommended by the australian national disability insurance scheme (ndis), as detailed in the supplementary material.10,12,19,57 in both schedules, the cost of labor corresponded to the number of hours allocated to a prosthetist for socket fittings. we considered that only a qualified prosthetist (e.g., a cpo) solely undertook all the labor at the standard australian hourly rate of $180. typically, ndis recommends that a prosthetist should spend approximately 32 hours for a socket fitting including six hours to cast the residuum, 20 hours to build the socket, and six hours to fit the socket. therefore, we allowed $5,760 for 32 hours to design and fit a socket as well as $360 for two hours to fit two liners, $1,800 for ten hours to fit the prosthesis, and $360 for two hours to maintain the prosthesis on an annual basis. the cost of a part corresponded to the typical portion of the total cost that is more likely to be subsidized by the government. we allowed $600 for parts per socket (e.g., socket valve, adapters), $1,000 for liners or sleeves, $1,400 for parts per prosthesis (e.g., tube, clamp, pylon) and $1,000 for basic cosmesis each year. https://doi.org/10.33137/cpoj.v4i2.36366 6 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e as recommended by the ndis, we allowed $3,000, $13,500, and $24,000 toward the provision of a knee unit every three years as well as $1,000, $2,750, and $4,500 toward the provision of a foot/ankle unit every two years for k1, k2, and k3 cases, respectively. government organizations such as ndis support the provision of categories of liners, sleeves, knees (e.g., single axis cadence responsive knee, affordable microprocessorcontrolled knees), and feet/ankles (e.g., dynamic foot, energy storing and return) depending on functional levels.32,58 prescription of components is left to the prosthetist, who chooses a model and brand accordingly to the patient’s specific needs. thus, we purposely allocated lump sums rather than price tags for specific prosthetic components. schedules differed by the number of sockets allowed per year. we assumed that k1 and k2 cases experienced issues with their residuum and sockets fittings before the k1 k2 k3 k2 k3 schedule of allowable expenses cost utility best-practice warranty schedules cost-utility literature review willingness-topay threshold scenario 2 scenario 3 scenario 5 schedule of allowable expenses k1 k1 k1 k2 k2 b a s e c a s e b e s tc a s e w o rs e c a s e retrospective analysis of sf36 data k1 k2 k3 k2 k3 baseline utility k1 k1 k1 k2 k2 assumption of utility gained s c e n a ri o s s o u rc e usu kwi icur kwi usu figure 2: overview of sources used to perform preliminary cost-utility analyses using incremental cost-utility ratio (icur) and willingness-topay threshold (wtp=$40,000 per qaly) to compare costs and utilities for the provision of transfemoral socket-suspended prostheses attached to residuum without (usu) and with distal weight bearing keep walking implant (kwi) over a six-year time horizon for five plausible clinical scenarios considering various progressions between k-levels (k1, k2, k3) including worse-case, base-case and best case. (sf36: 36-item short form survey). scenario 4 scenario 1 https://doi.org/10.33137/cpoj.v4i2.36366 7 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e intervention that were significant enough to require two socket fittings per year (table 2). we also hypothesized that the clinical benefits of the kwi should translate into a reduction of socket fittings from two to one per year for k1, k2, and k3 cases (table 3). we conservatively reduced and limited the yearly frequency of socket fittings down to one with the kwi to match the minimal provision supported by some healthcare systems. the total cost across all scenarios was $131,740±$14,378 without kwi and $108,580±$21,962 with the kwi, giving an incremental cost reduced by $23,160±$21,962 across all scenarios over the six-year time horizon (table 4). estimate utilities (step 3b) actual utility information is also yet to be available for a cohort of australians. we overcame this lack of primary utilities by analyzing outcomes of sf36 provided by guirao et al (2018) identified during step 1c.22 the authors recorded the utilities four months pre-operatively without the kpi and 14 months post-surgery with the kpi. a total of 23 individuals with unilateral tfa fitted with the kwi between march 2011 and november 2014 participated to this multicenter clinical study in spain (females: five (22%), males: 18 (78%); age: 52.65±15.6 years; height: 1,66±0,93 m; mass: 67.97±11.96 kg; bmi: 24.51±2.74 kg/m2; trauma: 11 (48%), oncologic: three (13%), vascular: nine (40%); clinical trial registration: 358/10/ec). key inclusion criteria for the recruitment were prior fitting of prosthesis for at least 12 months, prosthetic use for more than six hours per day, ability to walk indoors with or without supervision and ambulation aids, and unsatisfactory use of socket. the mapping of the sf36 data into qaly required information that was only partially presented in the initial publication. however, the authors provided all the raw data required to complete the analysis. first, the raw sf36 data were processed to produce the mean scores for the eight health dimensions as well as the physical and mental components summary scores. next, each sf36 dataset without and with the kwi was converted into qaly applying the ara and brazier regression model also used by frossard et al (2018).19,59 this provided a baseline utility of 0.788 and 0.845 qaly per year for provision of prosthetic care without and with the kwi, respectively. k-level classification during the recording of sf36 data was beyond the scope of the initial study.22 however, we prudently assumed that these baseline utilities were most likely to be experienced by k3 cases without and with the kwi, based on the aforementioned recruitment criteria (e.g., prosthetic use for more than six hours per day, ability to walk indoors with or without supervision, and ambulation aids). table 2: schedule of typical allowable expenses over six-year time horizon with yearly breakdown of labor and parts costs allocated for provision of transfemoral socket-suspended prostheses attached to residuum without distal weight bearing keep walking implant for each klevel (k1, k2). the number of units for all labor-related expenses corresponded to number of hours spent by a qualified prosthetist (e.g., cpo) at the standard australian fixed hourly rate of $180. tasks yearly cost total y1 y2 y3 y4 y5 y6 labor and parts for socket for all k-levels design and fit socket $11,520 $11,520 $11,520 $11,520 $11,520 $11,520 $69,120 fit liner $360 $360 $360 $360 $360 $360 $2,160 fit prosthesis $1,800 $1,800 $1,800 $1,800 $1,800 $1,800 $10,800 maintain prosthesis $360 $360 $360 $360 $360 $360 $2,160 total labor $14,040 $14,040 $14,040 $14,040 $14,040 $14,040 $84,240 socket valve, adapters $1,200 $1,200 $1,200 $1,200 $1,200 $1,200 $7,200 liner $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 $12,000 cosmesis $1,000 $1,000 $1,000 $1,000 $1,000 $1,000 $6,000 total parts $4,200 $4,200 $4,200 $4,200 $4,200 $4,200 $25,200 parts for k1 knee $3,000 $3,000 $6,000 foot $1,000 $1,000 $1,000 $3,000 tube, clamp, pylon $1,400 $1,400 $2,800 total parts for k1 $5,400 $1,000 $4,400 $1,000 $11,800 total for k1 $23,640 $18,240 $19,240 $22,640 $19,240 $18,240 $121,240 parts for k2 knee $13,500 $13,500 $27,000 foot $2,750 $2,750 $2,750 $8,250 tube, clamp, pylon $1,400 $1,400 $2,800 total parts for k2 $17,650 $2,750 $14,900 $2,750 $38,050 total for k2 $35,890 $18,240 $20,990 $33,140 $20,990 $18,240 $147,490 https://doi.org/10.33137/cpoj.v4i2.36366 8 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e table 3: schedule of typical allowable expenses over six-year time horizon with yearly breakdown of labor and parts costs allocated for provision of transfemoral socket-suspended prostheses attached to residuum with distal weight bearing keep walking implant for each klevel (k1, k2, k3). the number of units for all labor-related expenses corresponded to number of hours spent by qualified prosthetist (e.g., cpo) at the standard australian fixed hourly rate of $180. tasks yearly cost total y1 y2 y3 y4 y5 y6 labor and parts for socket for all k-levels design and fit socket $5,760 $5,760 $5,760 $5,760 $5,760 $5,760 $34,560 fit liner $360 $360 $360 $360 $360 $360 $2,160 fit prosthesis $1,800 $1,800 $1,800 $1,800 $1,800 $1,800 $10,800 maintain prosthesis $360 $360 $360 $360 $360 $360 $2,160 total labor $8,280 $8,280 $8,280 $8,280 $8,280 $8,280 $49,680 socket valve, adapters $600 $600 $600 $600 $600 $600 $3,600 liner $1,000 $1,000 $1,000 $1,000 $1,000 $1,000 $6,000 cosmesis $1,000 $1,000 $1,000 $1,000 $1,000 $1,000 $6,000 total parts $2,600 $2,600 $2,600 $2,600 $2,600 $2,600 $15,600 parts for k1 knee $3,000 $3,000 $6,000 foot $1,000 $1,000 $1,000 $3,000 tube, clamp, pylon $1,400 $1,400 $2,800 total parts for k1 $5,400 $1,000 $4,400 $1,000 $11,800 total for k1 $16,280 $10,880 $11,880 $15,280 $11,880 $10,880 $77,080 parts for k2 knee $13,500 $13,500 $27,000 foot $2,750 $2,750 $2,750 $8,250 tube, clamp, pylon $1,400 $1,400 $2,800 total parts for k2 $17,650 $2,750 $14,900 $2,750 $38,050 total for k2 $28,530 $10,880 $13,630 $25,780 $13,630 $10,880 $103,330 parts for k3 knee $24,000 $24,000 $48,000 foot $4,500 $4,500 $4,500 $13,500 tube, clamp, pylon $1,400 $1,400 $2,800 total parts for k3 $29,900 $4,500 $25,400 $4,500 $64,300 total for k3 $40,780 $10,880 $15,380 $36,280 $15,380 $10,880 $129,580 table 4: overview of total costs, utilities, incremental cost-utility ratio (icur) and differences between icur and willingness-to-pay threshold (wtp=$40,000 per qaly) for yearly provision of two and one sockets fitted transfemoral prostheses attached to residuum without (usu) and with distal weight bearing keep walking implant (kwi) for each k-level (k1, k2, k3) over a six-year time horizon, respectively. (scenarios 1: worse-case, scenarios 3: best-case, scenarios 5: base-case). scenario usu kwi incremental cost incremental utility icer below wtp klevel cost utility klevel cost utility ($) (qaly) ($) (qaly) ($) (qaly) ($/qaly) ($/qaly) scenario 1 k1 $121,240 4.443 k1 $77,080 4.868 -$44,160 0.424 -$104,033 -$144,033 scenario 2 k1 $121,240 4.443 k2 $103,330 4.969 -$17,910 0.526 -$34,056 -$74,056 scenario 3 k1 $121,240 4.443 k3 $129,580 5.071 $8,340 0.627 $13,295 -$26,705 scenario 4 k2 $147,490 4.585 k2 $103,330 4.969 -$44,160 0.384 -$114,975 -$154,975 scenario 5 k2 $147,490 4.585 k3 $129,580 5.071 -$17,910 0.485 -$36,890 -$76,890 mean $131,740 4.500 $108,580 4.990 -$23,160 0.489 -$55,332 -$95,332 sd $14,378 0.078 $21,962 0.085 $21,962 0.094 $53,459 $53,459 lower 95%ci $119,138 4.432 $89,330 4.915 -$42,410 0.407 -$102,190 -$142,190 upper 95%ci $144,342 4.568 $127,830 5.064 -$3,910 0.572 -$8,474 -$48,474 min $121,240 4.443 $77,080 4.868 -$44,160 0.384 -$114,975 -$154,975 max $147,490 4.585 $129,580 5.071 $8,340 0.627 $13,295 -$26,705 range $26,250 0.142 $52,500 0.203 $52,500 0.243 $128,270 $128,270 https://doi.org/10.33137/cpoj.v4i2.36366 9 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e finally, we cautiously assumed that k1 and k2 cases without kwi as well as k1 and k2 cases with the kwi might experience 6% and 3% as well as 4% and 2% less utilities than baselines, respectively (table 5). finally, the estimated utility values were cumulated over the six-year time horizon to provide total gain of qalys. we considered that the estimated utility values would remain unchanged over the time horizon like the health-related quality of life data reported by hagberg for a cohort of individuals with transfemoral bap over a 15-year follow-up study.60 the mean cumulated utility across all scenarios was 4.500±0.078 qaly without kwi and 4.990±0.085 qaly with the kwi giving an incremental utility increased by 0.489±0.094 qaly over the six-year time horizon (table 4). calculate incremental cost-utility ratios (step 3c) icurs was calculated using the formula icur = (cost with the kwi – cost without kwi) / (utility with the kwi – utility without kwi).18 individual icur was calculated for each scenario. we considered that an indicative icur corresponded to a base-case scenario. all icurs were plotted on a conventional cost-effectiveness plane diagram (figure 3).17 table 5: assumed percentage of utility gained in relation of baseline of 0.788 qaly per year and 0.845 qaly per year extracted from guirao et al (2018) as well as total qaly for time horizon following the provision of transfemoral socket-suspended prostheses attached to residuum without (usu) and with distal weight bearing keep walking implant (kwi) for each k-level (k1, k2, k3), respectively.22 the mean icur across all scenarios was -$55,332± $53,459 per qaly (table 4, figure 3). the provision of prosthetic care with the kwi was more costly and more effective than usual intervention only for base-case with an icur of $13,295 per qaly. prosthetic care with the kwi was less costly and more effective than usual intervention for all the other scenarios including worse-case and base percentage of decrease qaly per year qaly for time horizon usu k1 -6 0.741 4.443 k2 -3 0.764 4.585 k3 0 0.788 4.727 kwi k1 -4 0.811 4.868 k2 -2 0.828 4.969 k3 0 0.845 5.071 figure 3: cost-utility analysis showing incremental cost-utility ratio (icur) including the indicative icur of -$36,890 per quality-adjusted lifeyear (qaly) for the best-case and willingness-to-pay threshold (wtp) of $40,000 per qaly for the provision transfemoral socket-suspended prostheses attached to residuum without and with distal weight bearing keep walking implant (kwi) including quadrants indicating that provision with the kwi was more costly and more effective (quadrant a: consider icur), more costly and less effective (quadrant b: dominated), less costly and less effective (quadrant c: consider icur), less costly and more effective (quadrant d: dominant) than usual intervention. $(50,000) $(40,000) $(30,000) $(20,000) $(10,000) $ $10,000 $20,000 $30,000 $40,000 $50,000 -1.00 -0.50 0.00 0.50 1.00 c o s t (a u d $ ) health gain (qaly) wtp scenario 1 (worse-case) scenario 2 scenario 3 (best-case) scenario 4 scenario 5 (base-case) [d][c] [a][b] https://doi.org/10.33137/cpoj.v4i2.36366 10 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e case with a mean icur of -$72,489±$42,990 per qaly. the indicative icur corresponding to base-case was -$36,890 per qaly. compare with willingness-to-pay threshold (step 3c) the oft-cited wtp is $50,000 per qaly.17 we applied a conservative threshold of $40,000 per qaly, as suggested by the australian pharmaceutical benefits advisory committee.19 the mean icur across all scenarios was $95,332±$53,459 per qaly below wtp (table 4, figure 3). the icur for the provision of prosthetic care with the kwi corresponding to base-case was $26,705 per qaly below wtp. the icur for prosthetic care with the kwi for all the other scenarios including worse-case and base-case was $112,489± $42,990 per qaly below wtp. the indicative icur was $76,890 per qaly below wtp. interpret outcomes this three-step phase established whether the outcomes of this preliminary cua should facilitate or curtail further clinical introduction of the kwi in australia. consider limitations (step 4a) this study presented the typical limitations of preliminary cuas mentioned in frossard (2021) (e.g., narrow perspective, simple scenarios, short time horizon, strong assumptions, data mismatch, lack of uncertainty data).13,18 however, our assumptions resulted from educated choices made erring on the side of caution to estimate costs and utilities for a series of plausible scenarios. we prudently considered that the kwi could reduce socket fittings by only one compared to the usual intervention. consequently, some costs for labor and parts might have been overestimated. only a qualified prosthetist performed socket fittings, although some tasks could be undertaken by a technician paid at a lower hourly rate. we assumed that the full allowable expenses would be claimed, although previous studies demonstrated that consumers could spend less by choosing to keep using components after the warranty expired and/or overlook services and components (e.g., cosmetic covers).19,32 no costs were discounted. furthermore, utilities might have been underestimated. we conservatively credited baseline utility to k3 cases, allocated low incremental gains, and considered utilities gained post-treatment consistent over the years. however, the baseline utility was calculated retrospectively for a population in a jurisdiction where the perception of living without a limb, and therefore qaly, might be different than in australia. this cohort study had a small but reasonable sample size (n=23) representing approximately 30% of the existing population fitted with the kwi.22-25,61,62 finally, the interpretation of the icurs was limited by aggregation of costs and utilities with mismatched sources (i.e., estimated vs. real), jurisdictions (i.e., australia vs. spain), onset (i.e., 2018–2019 price vs 2011–2014 recruitment) and post-operative timeline (i.e., six-years vs. 14 months), respectively. however, we considered a conservative wtp that was approximately 20% or $10,000 below typical wtp. interpret outcomes (step 4b) the outcomes produced with the series of assumptions ascertained that the reduction of costs by 0.83±0.17 folds or $23,160±$21,962 combined with reasonable increase of 1.11±0.02 folds or 0.489±0.094 qaly could make the implantation of the kwi cost-effective and noticeably below wtp over a six-year time horizon from an australian governmental prosthetic care perspective. outcomes could be compared to recent cuas focusing on socket-suspended and socket-free bap solutions that were also performed with the same constructs, as detailed in the supplementary material.19,20,57 the costs for labor and parts, including knees and feet, were comparable to those considered in frossard et al (2017, 2018, 2020).12,19,20 however, baseline utility without and with the kwi extracted from guirao et al (2018) was 0.145 qaly or 0.225 folds and 0.202 qaly or 0.314 folds higher than the utilities experienced with socket-suspended and bap before and after implantation of osseointegrated percutaneous device reported in frossard et al (2018), respectively.19,22 the incremental utility extracted from guirao et al (2018) was 0.586 qaly or 0.911 folds less than the one reported in frossard et al (2018).19,22 interestingly, the average incremental utility across all the scenarios we considered in this study was 0.562±0.016 qaly or 0.873±0.024 folds less than the incremental qaly presented in frossard et al (2018).19 these comparisons confirmed that our estimations of costs and utilities for the provision of prosthetic care with the kwi were sensible. the proposed indicative icur for the provision of prosthetic care without and with the kwi was $125,099 per qaly or 5.94 folds, $445 per qaly or 0.02 folds, and $53,522 per qaly or 2.54 folds less costly than the icur for the provision of bap in the worse-case, best-case, and casebase presented in frossard et al (2018), respectively.19 the differences between the base-cases might be due to clinical guidelines recommending that bap should be fitted with advanced and costlier microprocessor-controlled knees and energy storing and return feet to protect the fixation (e.g., increase stance phase stability, avoid excessive loading, prevent falls) and reduce adverse events (e.g., periprosthetic factures, mechanical failures).32,58,63-66 https://doi.org/10.33137/cpoj.v4i2.36366 11 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e these comparisons suggested that the kwi has the potential to be more cost effective than current socketsuspended and other osseointegrated solutions, particularly when considering the base-case and worse-case scenarios. however, generalization of the outcomes intrinsic to the kwi must be considered carefully. the post-treatment baseline utility might be used in other studies. the costs extracted from australian-specific schedules might only be partially transferable to other jurisdictions worldwide, particularly in european and north american countries.7,52,54,67-70 outline implementation strategy (step 4c) the indicative icur appeared to stack up favorably against other socket-suspended or socket-free solutions currently available from an australian government prosthetic care perspective. furthermore, all icurs presented here were below the $20,000 per qaly threshold, making an innovation most likely to be recommended for clinical introduction, as described in frossard (2021).18 in sum, this preliminary cua provided sufficient favorable evidence to justify recommending market access and clinical introduction of the kwi, at least from an australian healthcare perspective. however, interpretation of these outcomes could be easily transferable to other healthcare organizations with a similar ethos worldwide. identifying pathways for the clinical introduction was beyond the scope of this study (e.g., training clinicians, testing site, registration of clinical trials, selection of participants). however, this study could inform subsequent full cuas of the kwi to be conducted within-trial horizon and beyond the trial follow-up for patients.49 primary cuas could consider true costs extracted from financial systems and utilities measured regularly with standard surveys for cohorts of participants treated without and with the kwi. in principle, prospective primary study could take several years because of the usual time required to implement the surgical procedure (e.g., clinical trial registration, ethical approval, recruitment of participants, surgical procedures, learning curve of practitioners, observation time between procedures). alternatively, primary analyses could aggregate actual and generic costs presented here and in other recent studies.19,20 meanwhile, modeling cuas could consider costs and utilities presented here to modify or develop specific bayesian or markov models.51 these analyses could predict the outcomes of kwi from broader health care perspectives aggregating utilities as well as fixed and ongoing surgical, medical, and prosthetic care costs over a scalable timeline (e.g., lifetime), assuming that issues with siloed healthcare financial systems could be overcome. assessments of health economic benefits of kwi using either primary or modeling approaches will benefit from stratified analyses considering a wide range of case-mixes with various demographics (e.g., young vs. elderly), causes of amputation (e.g., vascular vs. non-vascular), functional levels (e.g., k-level), attachments (e.g., socket vs. bap), multiple prosthetic fittings with liners, knees and ankles/feet (e.g., basic vs. advanced components) from healthcare, and societal perspectives (e.g., return to work).34,47,70,71 conclusions a preliminary cua comparing the provision of prosthetic care, particularly socket fittings, without (usual intervention) and with the kwi (new intervention) was performed for the first time. practically, this preliminary cua provided administrators of healthcare organizations in australia and elsewhere worldwide with prerequisite evidence justifying further market access and clinical promotion of the kwi. more broadly, this work indicates that a basic framework of preliminary cua of prosthetic care innovation proposed previously is not only feasible but also informative when a series of assumptions is carefully considered. this study further confirms that preliminary cuas might be a relevant alternative to full cua prosthetic care interventions, like any other medical treatment. call to action • share these outcomes with healthcare administrators australia and similar healthcare organization worldwide responsible for facilitating access to market of kwi solution. • suggest authors of health economic evaluations to use the information provided in this preliminary cuas and others to benchmark new innovations susceptible to ease prosthetic and, more particularly, socket fittings. • stimulate discussion amongst authors of health economic evaluations on how to capitalize on the lessons learnt from recent experiences including this work to identify a series of manageable barriers and transferrable facilitators of preliminary cuas of prosthetic care innovations. acknowledgements the author wishes to express their gratitude to alvaro alonso maturana for his support. declaration of conflicting interests lluis guirao is currently chief of the rehabilitation service hospital asepeyo sant cugat, barcelona, spain. lluis guirao is one of the inventors of the keep walking implant. he receives no monetary compensation related to the keep walking implant. beatriz samitier is currently rehabilitation specialist at servicio de rehabilitaión hospital asepeyo sant cugat, barcelona, spain. laurent frossard, director and chief scientist officer of https://doi.org/10.33137/cpoj.v4i2.36366 12 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e yourresearchproject pty ltd, was appointed as consultant by tequir s.l. to manage this project of research including collection, analysis, and reporting cost-effectiveness data. he has worked as consultant for several organizations on non-related educational programs and projects of research focusing on recording loading data, developing of database to record clinical outcomes as well as drafting grants and manuscripts for cognitive institute, exercise & sports science australia, griffith university, ipug pty ltd, middlesex university, new zealand artificial limb service, osseointegration group of australia pty ltd, ossur, poly-orthodox international, queensland artificial limb service, queensland university of technology, return to work-south australia, south australia health, tequir s.l, university of the new south whales, university of the sunshine coast. sources of support this study was partially funded by tequir s.l. and stable orthopaedics pty ltd. these companies had no influence on the design, data analysis, or interpretation of this research study. tequir s.l. provided technical information about the keep walking implant as well as the raw quality of life data and contributed to the writing of this manuscript. references 1.ghillebert j, de bock s, flynn l, geeroms j, tassignon b, roelands b, et al. guidelines and recommendations to 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provision of bone-anchored prostheses: governmental and practitioner perspectives. the aopa review. 2018; 3(1): 26-27. https://eprints.qut.edu.au/123164/ 10.frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. can prosthet orthot j. 2018; 1(2). doi: 10.33137/cpoj.v1i2.31326 11.frossard l, ferrada l, berg d. survey data on the quality of life of consumers fitted with osseointegrated fixation and boneanchored limb prostheses provided by government organization. data in brief. 2019; 26:104536. doi: 10.1016/j.dib.2019.104536 12.frossard l, merlo g, quincey t, burkett b, berg d. development of a procedure for the government provision of boneanchored prosthesis using osseointegration in australia. pharmacoeconomics. 2017; 1(4): 301-314. doi: 10.1007/s41669017-0032-5 13.frossard l. trends and opportunities in health economic 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orthot. 2019; 31(1s). 70.cutti ag, lettieri e, del maestro m, radaelli g, luchetti m, verni g, et al., stratified cost-utility analysis of c-leg versus mechanical knees: findings from an italian sample of transfemoral amputees. prosthet orthot int. 2017; 41(3): 227-236. doi: 10.1177/0309364616637955 71.frossard l. loading characteristics data applied on osseointegrated implant by transfemoral bone-anchored prostheses fitted with basic components during daily activities. data in brief, 2019. 26: 104492. doi: 10.1016/j.dib.2019.104492 authors scientific biography dr lluis guirao graduated from barcelona medical school at universidad central de barcelona in 1993. he works as a specialist in physical medicine and rehabilitation at hospital asepeyo sant cugat since 2018. he is also a professor at the sonography school of the spanish rehabilitation society-ecosermef and at san pablo andalucia ceu institute. dr lluis guirao is the principal investigator of the keep walking project (distal femoral implant) with the tequir s. l. team. https://doi.org/10.33137/cpoj.v4i2.36366 https://www.accessdata.fda.gov/cdrh_docs/pdf8/h080004d.pdf 15 guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.11. https://doi.org/10.33137/cpoj.v4i2.36366 issn: 2561-987x a preliminary cost-utility analysis of the keep walking implant guirao et al., 2021 cpoj special s p e c ia l i s s u e dr beatriz samitier graduated in medicine and surgery from university of zaragoza. she became a specialist in physical medicine and rehabilitation in 2007 and obtained a phd from universitat autónoma barcelona-uab. she is currently working as a physical medicine and rehabilitation specialist in the rehabilitation department in asepeyo sant cugat hospital, barcelona (spain). dr beatriz samitier is also a professor at the sonography school of the spanish rehabilitation society-ecosermef and at san pablo andalucia ceu institute. dr laurent frossard is a bionic limbs scientist who is passionate about developing ground-breaking prosthetic solutions to improve the lives of individuals suffering from limb loss. he is internationally recognized as a researcher and an independent expert for his unique expertise in bionic limbs. he approaches bionic solutions from a holistic perspective, by integrating the prosthetic biomechanics, clinical benefits, service delivery, and health economics. dr frossard has over 25 years of experience, both in academia and in private industries in australia, canada, and europe. he has collaborated with over 100 organizations worldwide. he is currently a professor of bionics at the griffith university, the director and chief scientist officer at yourresearchproject pty ltd, and adjunct professor at the queensland university of technology and the university of sunshine coast in australia. https://doi.org/10.33137/cpoj.v4i2.36366 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 literature review laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.35132 1 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 literature review the impact of ankle-foot orthoses on balance in older adults: a scoping review laidler j.l* department of rehabilitation therapy, faculty of health sciences, queen’s university, kingston, canada. introduction falls are the leading cause of injury among older adults in canada and are the third leading cause of death after cancer and heart disease.1 one in three adults over age 65,2 and one in two adults over age 80,3 experience at least one fall annually. falls are associated with high morbidity and mortality, and poor health outcomes.4,5 older adults experience more falls and have a high susceptibility to injury, making falls a significant public health issue. agerelated physiological changes coupled with a higher prevalence of comorbidities6,7 can result in older adults experiencing fractures, hospitalization, or early admission to a long-term care facility.8 greater than 70% of falls in the community occur in the home, due to both predisposing and situational risk factors.5 with increasing numbers of older adults wishing to stay in their homes and ‘age-in-place’, falls are of increasing concern. issues in balance control have been identified as a strong risk factor for falls.4 age-related sensory and musculoskeletal changes play a large role in affecting balance in older adults.5,8,9 decreased muscle mass is notable in aging and can lead to weakness resulting in inactivity, decreased balance control, gait deviations and instability during ambulation, and a lessened quality of life.7,10-12 age-related physiological changes can co-occur open access volume 4, issue 1, article no.1. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: balance impairment is a contributing factor to falls. falls are a leading cause of injury and death in older adults. an ankle-foot orthosis (afo) is a device that can be prescribed as an intervention to help individuals with compromised balance to ambulate safely. objective: the purpose of this review was to investigate the role ankle-foot orthoses have in affecting balance in community-dwelling older adults. methodology: a scoping review was conducted searching medline, cinahl, embase, and rehabdata databases to obtain the appropriate literature to meet the following criteria: 1) quantitative research design; 2) studies with participants over age 65; 3) studies with participants with drop-foot or sensory deficits in the lower extremity; 4) the treatment intervention was unilateral or bilateral afos; 5) the outcome measure was balance or stability. the retrieved articles were assessed based on the internal validity, external validity, objectivity, and reliability of the study design and the interpretation of results. findings: 11 articles were identified that met the inclusion criteria. four major themes emerged in the analysis about the impact that ankle-foot orthoses have on balance in older adults: (1) afos improved lateral stability, (2) afos improved balance under static conditions, (3) afos provided a reduction in postural sway and (4) afos increased walking speed in community-dwelling older adults. conclusions: the evidence from the findings of the review indicate that ankle-foot orthoses have a generally positive affect on balance in older adults. clinicians can consider the ankle-foot orthosis an effective intervention that can improve balance in some older adult patient populations. article info received: november 22, 2020 accepted: december 28, 2020 published: january 4, 2021 citation laidler j.l. the impact of anklefoot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i 1.35132 keywords ankle-foot orthosis, afo, older adult, aged, balance, postural balance, orthosis, scoping review, fall * corresponding author: jenna laidler, aging and health program, school of rehabilitation therapy, queen’s university, kingston, canada. e-mail: j.laidler@queensu.ca orcid: https://orcid.org/0000-0002-9875-6054 https://doi.org/10.33137/cpoj.v4i1.35132 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.35132 https://doi.org/10.33137/cpoj.v4i1.35132 mailto:j.laidler@queensu.ca 2 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj with the development of chronic condition(s), further compromising balance depending on underlying issues, and the strategies used to help manage them. ankle-foot orthoses (afos) are often prescribed for managing pathologies that affect typical functioning of the ankle joint in stability, positioning, and pressure distribution.13 an ankle-foot orthosis is a brace worn on the lower leg to hold the foot and ankle in position, defined by the international society for prosthetics and orthotics as an “externally applied device used to modify the structural and functional characteristics of the neuromuscular and skeletal system.”14 afos have been accepted as a treatment to address balance impairment, proper gait parameters, and safe ambulation for people with conditions such as stroke, peripheral neuropathy, multiple sclerosis, cerebral palsy and others.13 evidence exists to support the use of afos to improve ambulation and joint alignment, the next step is to determine what evidence exists regarding the effect of afos on balance. the objective of this review is to investigate the influence of afos during static and dynamic balance in older adults. the research question will be: what role do ankle-foot orthoses play in affecting balance in community-dwelling older adults? methodology a scoping review was conducted to identify the existing relevant literature available on the subject and to evaluate the research findings. scoping reviews examine the range and nature of research literature in a specific subject area, and commonly aim to identify gaps in the existing literature to determine the value of undertaking a full systematic review.15 the research question used to guide the review was “what role do ankle-foot orthoses play in affecting balance in community-dwelling older adults?” the definition of an older adult was men or women aged 65 or older. community-dwelling older adults were considered as those living in their own homes, not in institutions such as hospitals or long-term care. search strategy an electronic database search was conducted using four databases: medline, cinahl, embase, and rehabdata. these databases were selected because they contain literature pertaining to the health sciences, and they index the main journals that contain information related to healthcare and rehabilitation. to supplement these searches, a hand search of reference lists of retrieved articles was also conducted to identify potentially relevant studies. a combination of keywords and mesh terms were used to conduct the search. the search terms were as follows: orthotic device/orthotic brace/ankle-foot orthotic/afo; balance/postural balance; aged/older adults. mesh terms and corresponding keywords were combined in searches with ‘and’ or ‘or’ to ensure the articles retrieved contained all relevant terms. figure 1 illustrates the search strategy undertaken in each database (appendix (a)) for detailed database searches). literature from january 1990 to february 2020 were included in the search based on discussions with professionals in the field, as well as through database searches, which determined that limited literature existed on this topic prior to 1990. figure 1: example database search strategy. each number represents the database search performed and the results retrieved for each mesh term and keyword (1-6), the searches combining the corresponding mesh term and keyword (7,8,9), and the final search results combining all of the terms involved. article screening and selection process titles and abstracts of retrieved articles were screened for relevance to the research question based on the following criteria: 1) studies had a quantitative design; 2) participants were older adults over the age of 65; 3) participants had some degree of drop-foot or a sensory deficit in their lower extremity; 4) the treatment intervention was unilateral or bilateral ankle-foot orthoses; 5) the outcome measure was that of balance or stability. the full text of the remaining studies that were identified as relevant were screened for eligibility based on inclusion and exclusion criteria. studies were included if they met the following inclusion criteria: 1) participants were community-dwelling older adults, aged 65 and over; 2) study incorporated the use of unilateral or bilateral afos, regardless of design or fabrication material; 3) study described the effect of the afo(s) on balance; 4) study was written in english. studies were excluded from consideration if 1) the afo(s) had a mechanical/electrical component; 2) patients had partial foot amputations; 3) participants were in hospital or longterm care. these criteria were selected to ensure that the most appropriate patient population and study conditions were included in the analysis to address the research question. where possible, in studies with mixed-aged samples of participants under the age of 65, only data from those 65 and over were considered. each article was afo mesh or search results keyword 1 2 7 balance older adults mesh or keyword 3 4 8 mesh or keyword 5 6 9 https://doi.org/10.33137/cpoj.v4i1.35132 3 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj screened for eligibility based on whether it met these criteria, and whether the title and abstract contained the relevant content to address the research question to warrant full-text review. the reference management software endnote version x9.2 (endnote, clarivate analytics, pa, usa), was used to manage the citations of the retrieved articles. data extraction and analysis articles were selected based on their focus on the affect that afos have on balance in the older adult population. the full text of each article was examined by the reviewer and was assessed based on the internal validity, external validity, objectivity, and reliability of the study design and the authors’ interpretation of the results. key information was extracted and organized into a table to display the main ideas and characteristics of each study including study aim and findings, sample characteristics, study design, afo characteristics, balance metrics utilized, and strengths and limitations. the quality of each of the selected articles was also critically evaluated using a series of quality appraisal questions based on a combination of appraisal tools developed by casp16 and mcmaster university.17 quality was determined by using these questions to evaluate the methodological vigour of the study design and the soundness of the interpretation of findings presented in each article. based on the determined quality, a grade was assigned (from 1-low to 3-high) to each study, and a quality matrix was developed based on the quality rating to determine the weight of the evidence presented in each study (appendix (b)). higher quality evidence was weighted greater when considering its value in addressing the research question. articles were analyzed based on the similarities of subject characteristics and diagnoses, balance metrics recorded, and study design. the findings of each article were examined and compared for relevancy to answering the research question, and for emergent patterns on the effects afos produce on balance in older adults. results a total of 285 studies were retrieved from the database searches, 108 of which were duplicates and were disregarded. the titles and abstracts of 177 articles were screened for relevancy to answering the research question, producing 62 articles for full-text review. after the inclusion and exclusion criteria were applied, 11 articles remained for inclusion in the scoping review (figure 2). hand searches of reference lists yielded only duplicate or irrelevant studies, thus did not add to the search results. the emergent trends in the findings of each article were identified as the core themes existing in the current research literature and were the themes that were examined to help address the research question. the 11 articles included were selected because they focused on the affect that afos have on balance in the older adult population. through the quality appraisal and data analysis of each article, four major themes emerged: afos improved lateral stability, static balance and walking speed, and provided increased postural control. the quality matrix (appendix (b)) summarizes the quality rating and weighting of the evidence presented in each article. the summary of the main thematic ideas identified regarding ankle-foot orthoses’ affect on balance in older adults are found in table 1. the quality rating was inputted into the final column of the thematic summary table (table 1) and the data extraction table (appendix (c)). general overview of study characteristics the included studies were conducted in the netherlands,18,19 taiwan,20-23 turkey,24,25 and the united states.26-28 nine studies used a randomized pre-test/posttest design, in which the afo condition was compared with the no afo condition, and the order of the testing with and without the afo was randomized. two studies that were included were randomized control trials (rcts).18,27 records were searched from 1990 to present, and only one study was retrieved prior to 2005.21 sample sizes ranged from 1226 to 10322 subjects. the studies included a sample of participants in which forty-two percent were female, while fifty-eight percent were male. the ages ranged from twenty-six to eighty-four years, with the average age being 65. eight of the eleven included studies had patients who were recruited from outpatient rehabilitation hospital settings.18-25 the remaining studies recruited patients from community medical clinics or seniors support groups.26-28 the studies that recruited subjects from outpatient rehabilitation used samples of hemiplegic stroke patients as their subjects, and the three studies who recruited from the community setting included subjects with peripheral neuropathy or diabetes,26,28 or non-pathological subjects.27 the style of afos that were used varied across studies, as well as in the duration of time subjects had getting used to using them. afo designs utilized in the studies included thermoplastic posterior leaf-spring,18,22-24 thermoplastic anterior leaf-spring,20,21,27,28 anterior-shell carbon composite,26 thermoplastic hinged,25 or varying types.19 studies included both custom and prefabricated afos, with the majority of studies utilizing prefabricated versions. six studies tested the immediate balance effects of afos on subjects who had no prior experience using one,20,22,23,26-28 and five studies included subjects who had sufficient practice (>4 days) or used their own afo at study outset.18,19,21,24,25 eight of the eleven studies had their https://doi.org/10.33137/cpoj.v4i1.35132 4 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj subjects wear an afo on a single side (unilaterally),18-25 and three studies required their subjects to wear afos on both sides (bilaterally).26-28 themes lateral stability improved lateral stability with afo wear emerged as a theme throughout the literature. six studies included findings that lateral stability was improved while wearing an afo.21-23,26-28 it was found that afo wearers were able to shift their center of mass (com) more toward the afo side and therefore increase the lateral stability on this affected side. anterior/posterior balance was also measured with varying affects found on whether balance was affected due to afo wear. some studies observed limitations to anterior/posterior balance and suggested that the afo restricted natural ankle movement.21-23,26 chen et al.21 evaluated the effects of afos on postural stability in hemiplegic patients during weight shifting using force sensors and found significant improvements in lateral weight shifting and weight bearing on the afo side, with no improvement observed in the anterior/posterior direction. they attributed this to the ankle’s range of motion being restricted while wearing the afo. wang et al.23 found that in their study of assessing changes in balance and gait of hemiplegic subjects wearing afos, it was demonstrated that though afos restricted ankle movement, the presence or absence of wearing an afo did not significantly impact anterior/posterior balance measures during leaning tasks. all of the studies that found a positive relationship between afos and increased lateral stability, found this improvement in a static condition. static balance improvements in static balance as a result of wearing an afo was the most commonly observed theme in the reviewed studies.20-24,26-28 static balance was improved while wearing afo(s) in each of these studies and was more significant than measured improvements in tests of dynamic balance. many studies conducted trials primarily using static measures of balance, while only some included dynamic walking test conditions. all of these studies used a computer-based devices and software to attain their balance measures. cakar and colleagues24 investigated the relative effect of afos on balance and fall risk by comparing balance measurement outcomes within a group of stroke patients with spasticity to determine that afos improved balance, though they used exclusively static testing conditions. similarly, the studies by chen et al.,20 who evaluated the effects of an afo on postural stability in stroke patients with hemiplegia, and wang et al.,27 who investigated the effectiveness of afos on balance in older adults, also found improvements in balance while only testing in static conditions using force plate posturography and balance sensors, respectively. figure 2: flowchart diagram of the literature search, screen and selection process id e n tif ic a tio n s cr e e n in g in cl u d e d e lig ib ili ty records screened (n = 177) records excluded after title/abstract screen (n = 115) full-text articles assessed for eligibility (n = 62) full-text articles excluded (n = 51 did not meet inclusion criteria) studies included for full analysis (n = 11) records after duplicates removed (n = 177) records identified in medline (n = 103) records identified in rehabdata (n = 41) records identified in embase (n = 34) records identified in cinahl (n = 107) https://doi.org/10.33137/cpoj.v4i1.35132 5 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj postural control seven studies found a reduction in postural sway as a result of afo wear.18,20,23,25-28 postural sway, or postural control, was a variable measured to some capacity in all reviewed studies. in their investigation to determine the immediate effect of afo wear on balance and functional reach in older adults, yalla et al.28 found that afos decreased postural sway. bigelow & jackson26 found similar results in their investigation on the immediate effects of afos on balance and gait using force plates and clinical tests to produce findings that postural sway was reduced in static conditions, though the improvements in postural control in dynamic balance and walking conditions were more varied. doğan et al.25 and nikamp et al.18 were two studies with weaker evidence to support the afos ability to better control postural sway. doğan et al.25 investigated whether afos had an effect on stair climbing, balance, and mobility table 1: summary of the main ideas about the affect ankle-foot orthoses have on balance in older adults. author, year sample/ study design aim of study main themes quality rating lateral stability static balance postural control walking speed bigelow & jackson, 201426 n=12 subjects with peripheral neuropathy; pre-/post-test quantitative within-subjects comparison to observe the immediate effects of afos on balance and gait in individuals with peripheral neuropathy. x x x 3 cakar et al., 201024 n=25 subjects with post-stroke hemiplegia with spasticity; pre-/post-test quantitative within-subjects comparison to investigate the relative effect of afos on balance and fall risk. x 1 chen et al., 200820 n=21 subjects with new onset stroke hemiplegia + 10 healthy subjects; pre-/ post-test; quantitative cross sectional + control group comparison to evaluate the effects of an afo on postural stability in stroke patients with hemiplegia. x x 3 chen et al., 199921 n=24 hemiplegic subjects; pre-/ post-test quantitative within-subjects comparison to evaluate the effects of an afo on static and dynamic postural stability in hemiplegic patients. x x 1 doğan et al., 201125 n=51 subjects with post-stroke hemiplegia; pre-/post-test quantitative within-subjects comparison to investigate whether afos have an effect on stair climbing, balance and mobility while improving walking parameters. x x 1 nikamp et al., 201718 n=33 subjects with post-stroke hemiplegia; rct 6-month follow-up quantitative parallel group comparison to study the 6-month effects of early or late provision of afos in stroke patients; to look at differences between groups and functional improvement overtime. x x 2 simons et al., 200919 n=20 post-stroke subjects with hemiplegia; pre-/ post-test quantitative within-subjects comparison with washout period to examine effects of afos on functional balance, static and dynamic weight bearing asymmetry, and dynamic balance control. x 2 wang et al., 201927 n=44 non-pathologic subjects rct quantitative longitudinal (6month follow-up) to investigate effectiveness of afos on balance, fear of falling, and physical activity in older adults. x x x 3 wang et al., 200522 n=103 subjects with poststroke hemiplegia; pre-/ post-test quantitative between group comparison to examine the effects of afos on balance in patients with short and long duration hemiparesis. x x x 2 wang et al., 200723 n=58 subjects with post-stroke hemiplegia; pre-/ post-test quantitative within-subjects comparison to assess changes in balance, and improvement in gait of hemiplegic subjects as a result of wearing an afo. x x x x 2 yalla et al., 201428 n=30 subjects with diabetes and/or peripheral neuropathy; pre-/ post-test quantitative within-subjects comparison to determine the immediate effect of afos on balance and functional reach distance in older adults. x x x 2 https://doi.org/10.33137/cpoj.v4i1.35132 6 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj using functional measurement methods for which two of three functional tests showed a decrease in postural sway, and the third showed no effect. nikamp et al.18 conducted a six-month follow up to their previous rct to evaluate the effects of early or late provision of an afo for stroke patients and to observe the differences in functional improvements overtime between groups. they observed the trend that postural balance improved overtime and did not differ between groups. the remaining studies that did not show a reduction in postural sway, did not find a negative impact of afos on postural sway or balance control.19,21,22,24 walking speed five studies showed afos produced an effect on walking speed.18,19,22,23,25,26 with the exception of bigelow & jackson,26 who found that afos decreased walking speed, the remaining studies found that afos increased walking speed, with effects reported on improved gait parameters as well.22,23 in examining the effects of afos on balance in patients with shortand long-duration hemiplegia, wang et al.22 found that in addition to gait speed improving, cadence was also improved while wearing an afo in their clinical tests involving gait trials. simons and colleagues19 examined the effects that afos have on functional balance, and static and dynamic weight bearing asymmetry using posturographic and functional clinical tests with stroke patients wearing various afo designs. they found that walking speed was increased in all patients regardless of the style of afo worn. there was no consistent afo fabrication style or design used in the trials of other studies that demonstrated an increase in walking speed, only that they were all worn unilaterally. custommade versus prefabricated devices also had no apparent role on the balance outcomes of older adults in the included studies. quality of the evidence the articles deemed to be of the highest quality20,26,27 were found to have strong objectivity and reliability, while the articles found to be of the lowest quality21,24,25 were found to have poor external validity. the evidence presented in the examined articles was generally found to be of moderate quality. randomized control trials were considered to be at the top of the hierarchy of evidence,29 though only two were found to meet the inclusion criteria for the review.18,27 most authors randomized the orthotic conditions during pretest/post-test trials so that the participants could act as their own control, while only three studies actually included distinct comparison groups.18,20,27 the nikamp and colleagues18 study was an extension of their previous rct involving inpatients, to investigate the six-month effects of their intervention. though this study had elements of the strength of an rct, it was not considered to be as high quality in its ability to answer this review’s research question. the sample sizes in the reviewed studies were small, and all studies had under 60 participants except for one.22 through the quality appraisal procedure, the studies by wang et al.,27 chen et al.,20 and bigelow & jackson26 were considered to have the most procedurally sound designs and be the highest quality of the studies reviewed. these studies found that afos had an effect on balance by decreasing postural sway and improving balance under static conditions. in addition to balance improvements in these two areas, bigelow & jackson26 and wang et al.27 also found significant improvements in lateral stability as a result of wearing an afo. the trend that afos increase walking speed came from articles that were identified as moderate or low quality. discussion the aim of this scoping review was to investigate the role ankle-foot orthoses play in affecting balance in communitydwelling older adults. most studies found that with afo wear postural control was improved, especially in the lateral direction. it was also demonstrated that afos improved static standing stability, that did not necessarily transfer into improved stability in dynamic conditions, such as walking. the trends observed from the findings of these articles provided some insight into the role that afos play on affecting balance in older adults. main findings improved lateral stability lateral stability was widely found to improve amongst afo wearers in this review. the findings by wang et al.22 confirmed earlier findings by chen et al.,21 that through the use of an afo, the body’s limit of lateral stability is increased, and subjects were able to bear more weight through their hemiplegic side. wang et al.23 reconfirmed this finding in their 2007 investigation on changes in balance while wearing an afo, which again showed the afos ability to improve balance through increasing lateral stability. age-related declines in reaction time and physical strength can lead to impaired postural control in mobility. in a study on age-related differences in lateral stability, king, akula, & luchies30 found that compared to younger subjects, older individuals generated a larger force to recover balance to account for reduced lateral stability. age-related muscle weakness can affect an older adult’s ability to produce this response for balance recovery. impairments in balance control leave older adults more susceptible to falls, which are a major health issue, and a cause for injury and loss of independence in this population.31 https://doi.org/10.33137/cpoj.v4i1.35132 7 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj many of the reviewed studies acknowledge the lack of anterior/posterior balance improvement with afo wear and attribute it to restrictions imposed on the ankle by the afo.21-23,26 rigid afos decrease ankle range of motion, which yalla and colleagues28 speculate could increase risk for falling. however, wang et al.23 report that though the afo did restrict ankle movement, it did not significantly impact balance. this is supported by the investigation by chen et al.,20 on ankle strategies in balance responses, which found that despite the rigid ankle, patients were still able to elicit ankle strategies to maintain postural control while wearing afos. further investigation on the role afo ankle rigidity plays on balance is necessary. improved static balance improved balance during static standing conditions was the most commonly observed theme in the literature in this review. wang et al.22 examined stroke patients wearing afos under static standing conditions and found that balance improved. in reaching during static standing, yalla et al.28 found that the afos improved static balance. in interpreting these findings, it is important to take into account that many studies in the review only measured an afos affect on balance during static, rather than dynamic conditions. cakar et al.,24 for example, found that afos improved balance in spastic stroke patients under static conditions, however they did not include dynamic measures of balance in their study. dynamic balance was investigated in a study by shearin, smith, querry, & mccain32 to assess individuals’ ability to attend to external demands requiring modifications to balance while walking. the results of this study found that dynamic balance was improved in individuals wearing an afo. this finding was not validated in this review, and only one study23 demonstrated positive effects of afos on balance in a dynamic situation. as well, simons et al.19 found that the afo had no effect on either static or dynamic balance. further investigation is required to determine the afos role during dynamic balance. improved postural control afos were shown to affect postural control in this review. to maintain stability during standing, the body’s center of mass (com) must be positioned over the feet the base of support (bos).33 even during quiet standing in healthy individuals, the com experiences sway, though it is minimized when balance is proficient.34 moving the com outside of the bos leads to instability, which when combined with age-related changes in strength and reaction times,31 can cause an increased frequency of falls.35 stability and balance are significantly impacted when proprioception is impaired. multiple studies indicated the role that afos play in augmenting proprioceptive feedback on the lower leg and foot when deficits exist.20-22,26-28 in an investigation on the afos ability to provide sensory cues, aruin & rao36 found that afos can substitute for the lack of proprioceptive feedback in sensation impaired limbs to improve the postural responses. yalla et al.28 suggested that wearing an afo promotes proprioceptive feedback through stimulating cutaneous receptors. this is especially important for patients with peripheral neuropathy, and other pathologies that impair sensation. malas37 points to the important considerations this requires from orthotists when fitting an afo to ensure that pressure is properly distributed, enabling feedback to optimize stability. increased walking speed in the present review, all studies that reported improved walking speed contained a sample of hemiplegic stroke patients. since walking speed and cadence usually decrease in hemiparetic gait patterns,38 this finding suggests that the afo has a regulating effect on the gait patterns in this population. wang et al.23 attribute the increased walking speed to improved balance control in the affected leg that occurs as a result of wearing an afo. in a study on the impact afo design has on gait parameters in stroke patients, tyson & thorton39 reported that hingedafos better improved walking speed. pardo, galen, gahimer, & goldberg40 found similar results in their examination of hinged-afos effect on walking speed. in this review, only doğan et al.25 used a hinged-afo design, so this cannot explain the improvements observed. the studies that found improvements in walking speed with afos were of moderate quality, so further investigation into this effect is required. the style of afos worn in the different studies in this review were variable, with no consistent observations made on afo style and balance. pardo et al.40 investigated the outcomes of balance tasks in individuals wearing custom and non-custom (prefabricated) afos. the results indicated there was no difference in balance outcomes between custom-made and prefabricated devices. these findings complement the observation in this review, that outcomes on balance were not linked to custom-fabricated devices. limitations the primary limitation of this review was that only one author was involved in the quality appraisal process of the included studies. this may have introduced some reporting bias, and could have been strengthened had additional reviewers been involved in the process. the small number of studies included in the review and that all of the studies had small homogenous samples containing largely stroke patients, affects the confidence in the validity of the findings and limits their generalizability. it was found to be difficult to https://doi.org/10.33137/cpoj.v4i1.35132 8 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj obtain relevant literature with all participants over age 65. therefore, studies were included that had participants under age 65, if the majority of subjects were over age 65. a strength of this review was that studies were included from three different continents and found generally similar results on the effects afos have on balance in the older adult population. this provides reasonable confidence in the external validity of the findings within a specific population of patients. recommendations and implications for practice the findings of this scoping review generally support that afos affect balance in older adults in a positive way. the observation that though restrictions to the natural movement of the ankle can occur through wearing afos, the afos effect on improving proprioception appeared to remedy any potential deficit. this is an important clinical consideration when prescribing afos to patients who may have sensory deficits, to ensure the afo does not negatively impact the limitations their pathology imposes. this is pertinent information for healthcare providers who prescribe afos or work with afo wearing individuals, and the evidence derived from this review indicates the relevance of a more in-depth examination of literature in this subject area. this review did not display better balance outcomes for individuals wearing custom fabricated afos, suggesting that off-the-shelf, prefabricated afos may work sufficiently for certain patient populations. custom afos are substantially more expensive than their prefabricated counterparts, so healthcare providers must give consideration to appropriate use of the healthcare resources available when prescribing afos. the patient populations examined in this review were small samples of hemiplegic stroke and peripheral neuropathy patients. investigation into the effects afos have on other older adult populations with more diverse pathologies is an important area for future study to help substantiate the evidence found to support the afos affect on balance in these two specific patient groups. studies conducted with larger sample sizes in more diverse setting would aid in validating the findings of this review. conclusion the purpose of this review was to investigate the role afos play in affecting balance in community-dwelling older adults. given the many dimensions that comprise the ability to balance, evidence was examined for consistencies amongst findings for which aspects of balance were most impacted by afos. the afo was found to increase lateral stability, improve balance under static conditions, better control postural sway, and increase walking speed. the findings indicate that the afo has a generally positive affect on balance in older adults with hemiplegia and peripheral neuropathy, and supports the use of afos in patient populations with sensory impairments to improve balance and walking speed. investigation into the affects of afos on the balance of other pathologic patient populations and on balance during dynamic conditions warrants further research. acknowledgements the author of this article would like to express appreciation to dr. marcia finlayson, queen’s university, canada, for her assistance in preparing the current manuscript for publication. declaration of conflicting interests the author has no conflicts of interest to declare. sources of support no funding was provided for this review. ethical approval ethical approval was not needed for this study. references 1.statistics canada. causes of death, 2017; [internet].2019 [cited 2020 june 1]. available from: https://www150.statcan.gc.ca/n1/dailyquotidien/190530/dq190530c-eng.htm 2.hausdorff jm, rios da, edelberg hk. gait variability and fall risk in community-living older adults: a 1-year prospective study. arch phys med rehabil. 2001;82(8):1050–1056. doi: 10.1053/apmr.2001.24893 3.inouye sk, brown cj, tinetti me. medicare nonpayment, hospital falls, and unintended consequences. n engl j 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2014. 30.king gw, akula ck, luchies cw. age-related differences in kinetic measures of landing phase lateral stability during a balancerestoring forward step. gait posture. 2012;35(1):440-445. doi: 10.1016/j.gaitpost.2011.11.004 31.maki be, sibley km, jaglal sb, bayley m, brooks d, fernie gr, et al. reducing fall risk by improving balance control: development, evaluation and knowledge-translation of new approaches. j safety res. 2011;42(6):473-485. doi: 10.1016/j.jsr.2011.02.002 32.shearin sm, smith p, querry r, mccain k. bracing for persons with parkinson disease: a case series with clinical reasoning. j prosthet orthot. 2015;27(3):95-102. doi: 10.1097/jpo.0000000000000065 33.perry sd, radtke a, mcilroy we, fernie gr, maki be. efficacy and effectiveness of a balance-enhancing insole. j gerontol a biol sci med sci. 2008;63a(6):595-602. doi: 10.1093/gerona/63.6.595 34.yamamoto t, smith ce, suzuki y, kiyono k, tanahashi t, sakoda s, et al. universal and individual characteristics of postural sway during quiet standing in healthy young adults. physiol rep. 2015;3(3):1-24. doi: 10.14814/phy2.12329 35.conradsson d, paquette c, franze e. medio-lateral stability during walking turns in older adults. plos one. 2018;13(6):1-12. doi:10.1371/journal.pone.0198455 36.aruin as, rao n. ankle-foot orthoses: proprioceptive inputs and balance implications. j prosthet orthot. 2010;22(4 suppl):34-37. https://doi.org/10.33137/cpoj.v4i1.35132 10 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj 37.malas bs. the effect of ankle-foot orthoses on balance: a clinical perspective. phys med rehabil. 2010;10:24-33. doi: 10.1097/jpo.0b013e3181f4c1cb 38.hill kd, goldie pa, baker pa, greenwood km. retest reliability of the temporal and distance characteristics of hemiplegic gait using a footswitch system. arch phys med rehabil. 1994;75(5): 577-583. 39.tyson sf, thornton ha. the effect of a hinged ankle foot orthosis on hemiplegic gait: objective measures and users’ opinions. clin rehabil. 2001;15(1):53-58. doi: 10.1191/026921501673858908 40.pardo v, galen s, gahimer j, goldberg a. effect of custommolded and pre-fabricated hinged ankle-foot orthoses on gait parameters and functional mobility in adults with hemiplegic: a preliminary report. j prosthet orthot. 2015;27(1):33-38. doi: 10.1097/jpo.0000000000000053 https://doi.org/10.33137/cpoj.v4i1.35132 11 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj appendix (a) appendix (a): example database search strategy medline search strategy (literature search performed: february 2, 2020) 1. orthotic devices/ or braces/ 2. (afo or ankle foot ortho*) 3. exp# postural balance/ 4. balance 5. exp aged 6. older adult* 7. (orthotic devices/ or braces/) or (afo or ankle foot ortho*) 8. (exp postural balance/) or (balance) 9. (exp aged) or (older adult*) 10. ((orthotic devices/ or braces/) or (afo or ankle foot ortho*)) and ((exp postural balance/) or (balance)) and ((exp aged) or (older adult*)) cinhal search strategy (literature search performed: february 2, 2020) 1. (mh “orthoses+”) 2. “ankle foot orthosis or afo or orthotic” 3. (mh “balance, postural”) 4. “balance” 5. (mh “aged+) 6. “older adults” 7. ((mh “orthoses+”)) or (“ankle foot orthosis or afo or orthotic”) 8. ((mh “balance, postural”)) or (“balance”) 9. ((mh “aged+)) or (“older adults”) 10. [((mh “orthoses+”)) or (“ankle foot orthosis or afo or orthotic”)] and [((mh “balance, postural”)) or (“balance”)] and [((mh “aged+)) or (“older adults”)] embase search strategy (literature search performed: february 2, 2020) 1. exp ankle foot orthosis/ 2. (afo or ankle foot ortho*) 3. exp balance impairment/ 4. balance 5. exp aged/ 6. older adults 7. (exp ankle foot orthosis/) or ((afo or ankle foot ortho*)) 8. (exp balance impairment/) or (balance) 9. (exp aged/) or (older adults) 10. [(exp ankle foot orthosis/) or ((afo or ankle foot ortho*))] and [(exp balance impairment/) or (balance)] and [(exp aged/) or (older adults)] rehabdata search strategy (literature search performed: february 2, 2020) view articles, including international research, containing the exact phrase: '"ankle foot ortho*"', containing at least one of the word(s): '"balance"', where abstract contains: [(older and adult) or (ankle and foot) and (ortho* and balance) # exp= explode in database searches, the subject heading can be ‘exploded’ to include other more specific terms that are related to the initial subject heading in the search results. https://doi.org/10.33137/cpoj.v4i1.35132 12 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj appendix (b) appendix (b): quality appraisal and rating of studies reviewed a studies arranged in order of quality rating: 1 = weak; 2 = moderate; 3 = strong author, year neutrality objectivity consistency reliability applicability external validity truth value internal validity quality rating a wang et al., 201927 high high moderate moderate 3 chen et al., 200820 high high moderate moderate 3 bigelow & jackson, 201426 moderate high low high 3 wang et al., 200522 moderate high moderate moderate 2 wang, et al., 200723 moderate moderate low moderate 2 simons et al., 200919 moderate low low moderate 2 yalla et al., 201428 low moderate low moderate 2 nikamp et al., 201718 moderate high moderate low 2 doğan et al., 201125 low moderate low moderate 1 cakar et al., 201024 low moderate low moderate 1 chen et al., 199921 moderate low low low 1 https://doi.org/10.33137/cpoj.v4i1.35132 13 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj appendix (c) appendix (c): data extraction table – characteristics of the included studies author, year aim of study/paper sample size/ characteristics study design afo type & features balance measures main findings/ conclusions strengths and limitations article quality rating bigelow & jackson, 201426 to observe the immediate effects of afos on balance and gait in individuals with peripheral neuropathy. n=12 patients with peripheral neuropathy; convenience sample pre-/ post-test quantitative withinsubjects comparison anterior shell carbon composite afos prefabricated bilateral force plate posturographya • los • ap/ml sway + velocity clinical tests • minibestest • tug • gait speed afo has immediate improvements in static postural control but more variable responses during dynamic balance and gait. afos restrict ap los. no sig. difference in afo conditions for clinical balance and gait assessments. first time afo wearers, given same amount of practice time small sample reduced ordering effect did not use standard measures in dynamic balance tests 3 cakar et al., 201024 to investigate the relative effect of afos on balance and fall risk. n=25 hemiplegic long duration stroke patients with spasticity pre-/ post-test quantitative withinsubjects comparison thermoplastic posterior leaf spring afo prefabricated unilateral bbs postural stability test b fall risk test b afo improved balance and provided fall risk reduction in hemiparetic patients with mild/moderate spasticity; no difference in ap/ml stability scores. used verified & valid test measures excluded 2 outliner scores distance from researcher homogenous group of participants 1 chen et al., 199921 to evaluate the effects of an afo on static and dynamic postural stability in hemiplegic patients. n=24 hemiplegic patients; convenience sample pre-/ post-test quantitative withinsubjects comparison thermoplastic anterior leafspring afo prefabricated unilateral stabiloboardd weight-shift ap/ml max. balance postural sway & symmetry significant improvement in lateral weight shift and weight bearing through affected leg with afo. no difference in postural sway, postural symmetry or ap max. balance range with afo. poorly described study design; hard to replicate condition small homogeneous convenience sample dynamic postural stability was assumed random assignment to test condition 1 chen et al., 200820 to evaluate the effects of an afo on postural stability in stroke patients with hemiplegia. n=21 patients with new onset stroke (<3mo.) hemiplegia + 10 healthy subjects pre-/ post-test quantitative cross sectional + control group comparison thermoplastic anterior leafspring afo prefabricated unilateral postural stability c ankle strategy max stability cog velocity anterior afo may be used to assist early stage, hemiparetic stroke patients improve postural stability during stance by reducing cog velocity, lessening likelihood of falls. standardized test conditions random comparison group single, 1-hour session of testing only tested in static conditions 3 doğan et al., 201125 to investigate whether afos have an effect on stair climbing, balance and mobility while improving walking parameters. n=51 hemiplegic stroke patients pre-/ post-test quantitative withinsubjects comparison hinged afo with 90o pf stop custom made unilateral ashburn walking and stair test tug test bbs stream afos improved balance and ambulation activities in hemiparetic subjects. all subject showed improvement in gait speed, balance and mobility with afo use. no affect on stair climbing. large number of exclusion criteria larger sample then most other studies ceiling effects for some tests used instrumentation effect attrition effect 1 nikamp et al., 201718 to study 6month effects of early/late provision of afos in (sub)acute stroke patients to look at group differences and affects on functional improvement overtime. n=33 unilateral hemiplegic stroke patients max. 6 weeks post stroke early (wk 1) n=16; late (wk 9) n=17 rct 6 mo. f/u quantitative parallel group comparison 3 types of nonarticulated posterior leaf spring thermoplastic afos -rigid -semi-rigid -flexible prefabricated unilateral 10m walk test bbs fac 6 min walk test tug test stairs test barthel index rivermead mobility index no 6-month differences in functional outcomes of providing afos at different times in early rehab after stroke. in general, both groups of afo wearers improved over time registered rct underpowered maturation effect natural recovery poststroke no control group randomly assigned groups by 3rd party learning occurred out of clinical setting not possible to blind 2 https://doi.org/10.33137/cpoj.v4i1.35132 14 laidler j.l. the impact of ankle-foot orthoses on balance in older adults: a scoping review. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.1. https://doi.org/10.33137/cpoj.v4i1.35132 issn: 2561-987x afo affect on older adult balance laidler j.l. 2021 cpoj simons et al., 200919 to examine effects of afos on functional balance, static and dynamic weight bearing asymmetry, and balance control in stroke patients. n=20 hemiparetic stroke patients (at least 3 mo. post-stroke) pre-/ post-test quantitative withinsubjects comparison with washout period various flexible and rigid afo designs patient had own afo at study outset custom made+ prefabricated unilateral functional tests bbs tug 10m walk fac tbt posturo-graphic tests caren afo improved performance of functional tests, but had no effect on weight bearing asymmetry or dynamic balance. no effect on postural sway. increased walking speed highly sophisticated caren system washout period between trials attrition effect only measured ap not ml balance during perturbations 2 wang et al., 201927 to investigate effectiveness of afos on balance, fear of falling, and physical activity in older adults. n=44 non-pathologic patients with fear of falling, or previous fall rct; quantitative longitudinal (6mo f/u) flexible anterior gauntlet afo custom made bilateral tug ast postural sway (com, ankle, hip) afo + walking shoes improve balance compared to walking shoes alone and significantly reduces fear of falling. increased lateral stability registered rct many exclusions non-pathologic participants underpowered attrition effect25% dropout rate history effect 3 wang et al., 200522 to examine the effects of afo on balance in patients with short and long duration hemiplegia. n=103 subjects with long (>12mo)/ short(<6mo) duration unilateral hemiparesis sd n=42 ld n=61 pre-/ post-test quantitative between group comparison thermoplastic afo prefabricated unilateral standing balance c cog velocity, excursion, accuracy los sit-to-stand bbs 10m walk test afo improves symmetry in static + dynamic balance, and increases gait speed and cadence in subjects with short duration hemiparesis. effects not observed for long duration subjects. largest sample size in data set no control group cane used in walking trials test sequence random gait assessed by independent physiotherapist 2 wang et al., 200723 to assess changes in balance, and improvement in gait of hemiplegic subjects as a result of wearing an afo n=58 subjects with hemiparesis (within 6 mo. post-stroke) pre-/ post-test quantitative withinsubjects comparison thermoplastic afo prefabricated unilateral standing balance c cog velocity and excursion los gait parameterse (time/distance) afo improved dynamic balance and increased walking speed in hemiparetic subjects. increased lateral weight bearing on afo side random test sequence researcher performed tests walking speed much faster than previous studies’ findings 2 yalla et al., 201428 to determine the immediate effect of afos on balance and functional reach distance in older adults n=30 diabetic/ peripheral neuropathy -excluded hemiplegics pre-/ post-test quantitative withinsubjects comparison flexible anterior gauntlet afo bilateral custom made postural swayf com, ankle, hip forward reach test tug wearing afo reduced postural sway and improved lower extremity coordination in subjects without interfering with their ability to perform adls less restricted patient population than other studies clear/consistent protocol instrumentation effects sensors vs. force plate used 2 los=limit of stability; tug=timed up and go; ap= anterior-posterior; ml=medial-lateral; bbs=berg balance scale; cog=centre of gravity; pf=plantar flexion; stream=stroke rehabilitation assessment of movement; fac=functional ambulation categories; tbt=timed balance trial; ast=alternate-step test; adls=activities of daily living a from bp5050 (bertec corporation, columbus, oh, usa) b from biodex balance system (biodex medical systems, shirley, ny, usa) c from smart balance master system (neurocom international, inc., clackamas, or, usa) d from computer dyno graphy system (market-usa inc., severna park, md, usa) e from gaitrite system (cir system inc., franklin, nj, usa) f from balansenstm sensors (biosensics llc, boston, usa) https://doi.org/10.33137/cpoj.v4i1.35132 volume 6, issue 2 2023 articles in this special issue has been invited and reviewed by dr. silvia ursula raschke and dr. hossein gholizadeh. d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e v o l u t i o n i n p r o s t h e t i c s & o r t h o t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x https://jps.library.utoronto.ca/index.php/cpoj/editorinchief 1 baschuk c.m. 3d printing and the evolution of partial hand prostheses: my journey from theory to practice. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.5. https://doi.org/10.33137/cpoj.v6i2.42139 stakeholder perspectives 3d printing and the evolution of partial hand prostheses: my journey from theory to practice baschuk c.m* point designs, llc, bountiful, ut, usa. introduction additive manufacturing (am), commonly known as 3d printing, is revolutionizing the field of prosthetics, particularly in the space of partial hand and/or finger prostheses. unlike traditional methods which often require molds, casts, and extensive manual labor, additive manufacturing provides a more streamlined, customizable, and cost-effective approach.1 there are three distinct areas in which additive manufacturing offers additional advantages over traditional prosthetic fabrication processes such as laminations and vacuum forming (table 1). the success of a prosthesis hinges on the proper integration of materials, design, and manufacturing methods by the prosthetist. when balanced, these components yield a prosthesis that harmoniously merges technology with the user's daily life. this interdependence is of particular importance in the provision of partial hand and finger prostheses. upper limb differences the partial hand and/or finger difference community is a significant yet often overlooked segment of the broader limb difference population. despite being the largest group of individuals with upper limb differences, this demographic has historically been underserved in terms of research attention, rehabilitation resources, and prosthetic innovation. they are often told their loss or difference is only minor and that they will just adapt to it. a study by zieglergraham et al. indicates that partial hand amputations account for nearly 90% of all upper limb amputations, underscoring the prevalence of this specific condition.2 however, prosthetic solutions and rehabilitation programs have disproportionately focused on more proximal levels of amputation, such as transradial or transhumeral, leaving a gap in care for those with partial hand amputations.3 historically, prosthetic options for partial hand and finger differences were limited in scope and functionality in large part due to the difficulty of integrating the prosthesis with the residual anatomy. early solutions were primarily cosmetic, offering passive silicone or rubber prostheses that aimed to replicate the appearance of missing fingers or parts of the hand without providing any meaningful function.4 in the 1970’s, advances in materials and technology introduced mechanical finger and partial hand prostheses. these open access abstract the world of prosthetics has been undergoing significant changes, with the evolution of materials, design techniques, and manufacturing methodologies converging to redefine the landscape. central to this narrative is the imperative for a holistic approach, harmonizing the trinity of materials, design, and methodologies to yield optimal outcomes. this balance is especially pivotal for the overlooked yet significant segment of those with partial hand and finger differences. historically, this demographic has been underserved, with rehabilitation and prosthetic innovations often falling short. the sheer prevalence of partial hand differences underscores the urgency of tailored solutions. traditional fabrication methods like wet lamination have posed challenges, particularly in aligning and efficiency. the advent of additive manufacturing has been transformative. the case of designing and printing a partial finger socket for point designs, llc's point partial finger highlights this paradigm shift. where conventional techniques demanded hours, digital design and 3d printing have condensed the process to mere minutes, without compromising on quality. this is not merely a win in terms of time efficiency; the implications for the end users are profound, ensuring a more customized and efficient solution. the journey underscores the potential of blending technology and traditional prosthetic knowledge, pointing towards a future where prosthetics align more seamlessly with users' needs. citation baschuk c.m. 3d printing and the evolution of partial hand prostheses: my journey from theory to practice. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.5. https://doi.org/10.33137/cpoj.v6i 2.42139 keywords prosthetics, additive manufacturing, 3d printing, partial hand, finger amputation, material science, cad, biomechanics, user-centered design, rehabilitation, multi-jet fusion * corresponding author: christopher m baschuk, mpo, cpo, faaop(d) point designs, llc, bountiful, ut, usa. e-mail: chris@pointdesignsllc.com orcid id: https://orcid.org/0000-0002-9895-5897 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.5. 2023 special issue https://doi.org/10.33137/cpoj.v6i2.42139 https://doi.org/10.33137/cpoj.v6i2.42139 https://doi.org/10.33137/cpoj.v6i2.42139 mailto:chris@pointdesignsllc.com https://orcid.org/0000-0002-9895-5897 https://jps.library.utoronto.ca/index.php/cpoj/index 2 baschuk c.m. 3d printing and the evolution of partial hand prostheses: my journey from theory to practice. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.5. https://doi.org/10.33137/cpoj.v6i2.42139 canadian prosthetics & orthotics journal issn: 2561-987x 3d printing and the evolution of partial hand prostheses baschuk c.m, 2023 (special issue) devices, made of materials like stainless steel, aluminum, and durable plastics, provided some degree of grip or pinch through cable-operated or body-powered mechanisms.5 while they marked an improvement over cosmetic options, they still lacked the dexterity and intuitiveness of natural finger movement.6 the innovation in this space stagnated until the early 2000’s. table 1: benefits of 3d printing in prosthetic design and fabrication. category benefits materials • expansive array of materials, from flexible thermoplastics to strong polymers. • ability to layer or combine materials for desired textures, flexibility, and strengths. • nuanced material choices tailored to user needs. design flexibility • precise tailoring to the user's anatomy using digital software. • incorporation of advanced features like lattice structures for weight reduction. • user-driven designs with aesthetic and functional preferences. manufacturing methods • customizability inherent in layer-by-layer additive manufacturing. • ability to create complex structures unachievable with traditional methods. • precise control over prosthetic socket wall characteristics. • digital simulation and validation prior to physical production. • ease of making adjustments to designs. the challenges a prosthetist faces in meeting specific needs of individuals with partial hand and/or finger differences are complicated by the fact that no two hand presentations are ever exactly the same. the underlying cause of the partial hand or finger difference combined with differing surgical paradigms and general lack of knowledge amongst surgeons regarding prosthetic options for this population creates a wide variety of presentations even amongst individuals with the same parts of their hands or fingers involved.7 meeting the functional needs of this patient population has been quite challenging. many surgeons don’t even refer these individuals to prosthetists. when they do, the local prosthetist may not be aware of all the options currently available to restore the form and function of the involved hand and/or fingers through prosthetic rehabilitation. the intricacies and functional demands of hands, coupled with the unique biomechanics of fingers, require specialized knowledge and design considerations. yet, due to their foundational experience in lower extremity socket designs and lack of educational resources on the topic, many prosthetists unconsciously gravitate towards utilizing familiar techniques. this results in partial hand prosthetic sockets that might be shaped like a hand, but from a design, materials, and manufacturing methods standpoint are essentially lower limb prosthetic sockets fit on hands. such designs, while made with the best intentions, may not capture the full range of motion, tactile sensitivity, and versatility required of a hand prosthesis. hence, there's a pressing need for specialized training and awareness among prosthetists to ensure that upper limb prostheses, particularly for the hand, are tailored for optimal function and user comfort. given these challenges, would the more widespread adoption of additive manufacturing in the production of partial hand prostheses be beneficial? 3d printing if i had to give you a one-word answer now it would be an emphatic, “yes!” but that hasn't always been the case. in fact, i had significant reservations about the way in which it was being applied for several years starting around 2014. the idea of using 3d printing for prosthetics began gaining traction in the early 2010s, particularly with the advent of more accessible and affordable desktop 3d printers utilizing fused deposition modeling (fdm). one of the early and most notable 3d-printed prosthetic projects was the robohand, which was a partial hand prosthesis codeveloped by richard van as, a carpenter from south africa who lost several of his fingers in a woodworking accident, and ivan owen, a special effects artist and puppeteer from the united states.8,9 their efforts generated a lot of hype over the use of additive manufacturing and its application to upper limb prostheses. some groups tried to emphasize the lower cost of materials, sans the clinical care needed to effectively provision upper limb prostheses, to vilify our profession; making prosthetists out to be greedy for charging upwards of $80,000 for a myoelectric prosthesis when a prosthesis could be printed at home for only $50. in 2015, marvel studios and disney even got involved when they had robert downey jr, as ironman, deliver a 3d printed prosthesis to a young boy that was made to look like the ironman gauntlet.10 there was no indication that a prosthetist was involved in the fitting process even though it occurred in a us state that has licensure for prosthetics and orthotics. the social and traditional media loved the story, and it went viral. this created a stir within the national prosthetic and orthotic organizations in the united states. some went so far as to call for an outright ban on the use of 3d printing in prosthetics and orthotics. the problem was those calling for bans were erroneously vilifying the manufacturing method, just like those 3d printing groups were erroneously vilifying us, the manufacturers. concerned about these misconceptions, i wrote an article promoting the acceptance and collaboration around 3d printing in prosthetics.11 i saw the potential that additive manufacturing could have for upper limb prosthetics and feared that due to misconceptions and unsafe applications it would be cast off https://doi.org/10.33137/cpoj.v6i2.42139 3 baschuk c.m. 3d printing and the evolution of partial hand prostheses: my journey from theory to practice. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.5. https://doi.org/10.33137/cpoj.v6i2.42139 canadian prosthetics & orthotics journal issn: 2561-987x 3d printing and the evolution of partial hand prostheses baschuk c.m, 2023 (special issue) by our profession. one of additive manufacturing’s greatest strengths is that it can produce high complexity, low-volume components in a cost-efficient manner. upper limb prostheses are exactly that, highly complex and produced in low volumes. however, they also need to be durable, and the fdm manufacturing methods being used were lacking in this area. a real breakthrough in the practical application of additive manufacturing in prosthetics came with the increased accessibility of powder bed printing technologies such as selective laser sintering (sls) and, in 2016, multi-jet fusion (mjf). the introduction of materials like pa12 and pa11, which are nylon variants, ushered in a new era of prosthetics. these methods were able to produce end products with greater strength, homogeneity, and higher resolution, than fdm. they also lacked the distinct layer lines of fdm. these advancements allowed for the creation of innovative prosthetic designs, previously inconceivable with traditional methods, marking a revolutionary shift in the prosthetic manufacturing domain. the arrival of the mjf technology influenced my decision to begin implementing a hybrid workflow into my clinical practice. between 2019 and 2021 i began to utilize hand casting for shape capture in order to achieve an optimal impression to start from. then i would digitize the impression with a 3d scanner and utilize geomagic freeform plus software to rectify the model and to design the prosthesis. i initially found myself recreating designs of prostheses that i could have traditionally fabricated. as i became more comfortable with the principles of designing for additive manufacturing (dfam) i would begin to integrate more complex geometries and features; creating prostheses that couldn’t have been produced through any other method than additive manufacturing. i would generally use fdm prints for my diagnostic sockets and then multi-jet fusion printing for the definitive sockets. i discovered that the sockets i was making were lighter and lower profile because of the ability to fine tune the socket and wall geometry with a freedom that i hadn’t experienced before. not to mention, my favorite feature of digital socket fabrication, the undo button; a luxury not found in plaster modifications or laminations. in 2021, i embarked on a transformative journey by designing and printing my first partial finger socket for point designs, llc's point partial finger. my previous reliance on traditional wet lamination methods proved cumbersome and inefficient, often grappling with the small size and alignment complexities inherent in such a design. an alignment mishap in a previous project further highlighted the limitations of these traditional techniques, sparking my interest in the potential of additive manufacturing. collaborating with point designs, we innovated a mounting bracket that seamlessly melded with additively manufactured sockets. where traditional methods consumed several hours, my foray into digital design and printing shrunk the fabrication process of the point partial socket to just 30 minutes of design time. printing took a passive role in the background, allowing me to focus on other responsibilities. upon receipt from the printer, assembling the components was a matter of minutes. from several laborious hours, the process was now streamlined to roughly 40 minutes – a testament to the game-changing nature of additive manufacturing. what i initially saw as a time-saving measure for myself had broader implications. this advancement was not just about clinician convenience, but it signified a paradigm shift with profound benefits for the end users, enhancing their experience and changing the prosthetic landscape. in late 2022 utilizing the principles of dfam, i came up with an idea for a radically different design of a partial hand prosthesis. it was designed to be rigid where the prosthetic fingers mounted, but also minimized the area of the rigid portions and replaced them with flexible regions where the residual hand needed to move. the first person that i fit with this design was jeff soelberg. after an industrial accident in 2016, jeff lost digits 2-4 on his right hand. over the years, he tried multiple prostheses; three of them having carbon fiber laminated frames. each of the carbon fiber sockets felt different to jeff. collaborating with point designs in january 2023, jeff tried the customized 3d printed prosthesis for the first time. he expressed, "the difference between a carbon fiber laminated and the 3-d printed frame is night and day." jeff instantly felt that the 3d printed frame would be transformative. previously, he wore his prosthesis sporadically depending on his activities. since acquiring the 3d printed prosthesis, he puts it on in the morning and wears it until bedtime, describing the fit as a "well-tailored glove". (figure 1) one of his major challenges had been finding suitable work gloves. earlier, he always had to customize gloves to wear them. with the 3d printed design, he can now easily purchase gloves off-the-shelf. he mentioned, "before my prosthetic was a tool. today, it's an extension of my right hand. i feel better with it on than not having it on." his experience with the new design has transformed his daily life. he confidently recommends the 3d printed frame, highlighting its reproducibility. he emphasized, "if something happens, you just call your cpo, and they print a new one that fits like the old one. it's much easier than the old way." with such strong endorsement and the evident benefits of flexibility, customization, and the pa12 nylon material, jeff's journey showcases the promise and impact of advancements in prosthetic technology. he firmly states, "i never want to go back to a carbon laminated prosthesis." https://doi.org/10.33137/cpoj.v6i2.42139 4 baschuk c.m. 3d printing and the evolution of partial hand prostheses: my journey from theory to practice. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.5. https://doi.org/10.33137/cpoj.v6i2.42139 canadian prosthetics & orthotics journal issn: 2561-987x 3d printing and the evolution of partial hand prostheses baschuk c.m, 2023 (special issue) i’ve found numerous advantages of additive manufacturing over traditional fabrication methods in prosthetic design. while traditional methods require manual adjustments and often result in imperfect fits, 3d printing allows for precise, digital planning that ensures components fit seamlessly on the first try. this reduces the painstaking manual work, like drilling and filing, previously needed to achieve a flush finish on prostheses. additive manufacturing also boasts reproducibility; if a prosthesis breaks, is lost, or stolen, the design can be easily re-evaluated, adjusted if needed, and reprinted at a minimal cost, ensuring the initial hard work in optimizing the fit is never wasted. figure 1: top row showing dorsal and palmar views of jeff's carbon fiber laminated prosthesis. bottom row showing dorsal and palmar views of jeff's additively manufactured prosthesis. the significant difference in bulk and rigid areas between the two prostheses is clearly seen. conclusion in conclusion, additive manufacturing is not just a new tool in the prosthetist's arsenal; it's a paradigm shift. it democratizes the design and production process, making advanced, customized partial hand prostheses more accessible and adaptable to the end user. there is a misconception by some that 3d printing is a panacea for prosthetic rehabilitation. yet, there are still others for whom 3d printing is anathema. the appropriate application of 3d printing in this space is one of the biggest challenges that is still being debated. it makes no sense to design a prosthesis according to the same designs we have historically made and then 3d print it. if you can make the prosthesis with traditional fabrication methods effectively, why would you go through the trouble of 3d printing it? there is so much more that can be done and integrated into a prosthesis with a shift in the ethos to a dfam paradigm, than can be done with traditional manufacturing. the advancements seen in the last 10 years with prosthetic options available for individuals with partial hand and/or finger differences as a result of the appropriate application of additive manufacturing materials, methods, and designs is a clarion call for further innovation in this space. of all the places where additive manufacturing has been applied in prosthetic rehabilitation, the application to prostheses for the partial hand and/or finger difference populations has been one of the most if not the most transformative and will continue to be going forward. afterall, 3d printed partial hand and finger prostheses were the catalyst that brought visibility and growing widespread application of additive manufacturing into prosthetic rehabilitation. call to action you don’t need to invest a lot of money or buy a 3d printer of your own to begin the process of implementing additive manufacturing into your own clinical practice. i would encourage anyone who wants to get started to download meshmixer, a free organic modeling software and spend some time on youtube watching tutorials. that is what i did initially, and it doesn’t cost anything but your time. learning the principles of dfam takes some time to comprehend but is essential to produce functional prostheses. finally, i would encourage you to reach out to individuals on linkedin, for example, that you see posting about the prostheses that they are creating with additive manufacturing. many of them, including myself, are more than willing to become a mentor to you. acknowledgements i would like to acknowledge tom passero, cp, president and founder of handspring clinical services, for providing me with the opportunities, tools, and resources i needed early on in my career https://doi.org/10.33137/cpoj.v6i2.42139 5 baschuk c.m. 3d printing and the evolution of partial hand prostheses: my journey from theory to practice. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.5. https://doi.org/10.33137/cpoj.v6i2.42139 canadian prosthetics & orthotics journal issn: 2561-987x 3d printing and the evolution of partial hand prostheses baschuk c.m, 2023 (special issue) to help my dream of becoming a specialist in upper limb prosthetics a reality. declaration of conflicting interests i currently am employed by point designs, llc as the director of clinical services and have been since may of 2022. this work is my own from my own personal experience both prior to my employment with point designs as well as during. all opinions or statements are my own and do not necessarily reflect the views or opinions of point designs, llc. sources of support none. references 1.diment le, thompson ms, bergmann jh. clinical efficacy and effectiveness of 3d printing: a systematic review. bmj open. 2017;7(12):e016891. doi: 10.1136/bmjopen-2017-016891 2.ziegler-graham k, mackenzie ej, ephraim pl, travison tg, brookmeyer r. estimating the prevalence of limb loss in the united states: 2005 to 2050. arch phys med rehabil. 2008;89(3):422-9. doi: 10.1016/j.apmr.2007.11.005 3.atkins dj. epidemiologic overview of individuals with upper-limb loss and their reported research priorities. j prosthet orthot. 1996;8(1):2-11. doi:10.1097/00008526-199600810-00003 4.biddiss e, chau t. upper limb prosthesis use and abandonment: a survey of the last 25 years. prosthet orthot int. 2007;31(3):23657. doi: 10.1080/03093640600994581 5.pylatiuk c, schulz s, döderlein l. results of an internet survey of myoelectric prosthetic hand users. prosthet orthot int. 2007;31(4):362-70. doi: 10.1080/03093640601061265 6.cordella f, ciancio al, sacchetti r, davalli a, cutti ag, guglielmelli e, et al. literature review on needs of upper limb prosthesis users. front neurosci. 2016; 10:209. doi: 10.3389/fnins.2016.00209 7.graham em, hendrycks r, baschuk cm, atkins dj, keizer l, duncan cc, et al. restoring form and function to the partial hand amputee: prosthetic options from the fingertip to the palm. hand clin. 2021;37(1):167-187. doi: 10.1016/j.hcl.2020.09.013 8.owen i. life-enhancing prosthetics: 3d printed and open-sourced [internet]. tedxrainier; [cited 2023 aug 30]. available from: https://tedxseattle.com/talks/life-enhancing-prosthetics-3d-printedand-open-sourced-ivan-owen-at-tedxrainier/ 9.fast company. how two guys got together to build a new hand [internet]. fast company; [cited 2023 aug 30]. available from: https://www.fastcompany.com/1680656/how-two-guys-gottogether-to-build-a-new-hand 10.seven-year-old gets 3d-printed iron man prosthetic from robert downey jr. [internet]. the verge; [cited 2023 aug 30]. available from: https://www.theverge.com/2015/3/13/8207133/3d-printediron-man-prosthetic-limbitless-solutions 11.baschuk c. the synergistic potential of embracing 3d printing in o&p [internet]. linkedin; [cited 2023 aug 30]. available from: https://www.linkedin.com/pulse/synergistic-potential-embracing3d-printing-op-chrisbaschuk/?trackingid=7bf1k07eqxwdnudtvr%2fa1a%3d%3d author scientific biography chris baschuk, mpo, cpo, faaop(d), stands at the forefront of upper limb prosthetic rehabilitation, fervently advocating for the transformative potential of additive manufacturing. as the director of clinical services at point designs, llc, he has pioneered the integration of advanced manufacturing techniques with silicone customization to enhance prosthetic solutions for individuals with partial hand and finger differences. a graduate of the university of utah in biomedical engineering and ut southwestern medical center in prosthetics and orthotics, chris's academic and research contributions have been profound. recognized as a fellow with distinction by the american academy of orthotists and prosthetists, he has chaired the upper limb prosthetics society since 2017. chris's extensive peer-reviewed publications and global lectures underscore his influence in the field. beyond academia, he passionately advocates for prosthetic rehabilitation access, ensuring optimal care for those in need. https://doi.org/10.33137/cpoj.v6i2.42139 https://tedxseattle.com/talks/life-enhancing-prosthetics-3d-printed-and-open-sourced-ivan-owen-at-tedxrainier/ https://tedxseattle.com/talks/life-enhancing-prosthetics-3d-printed-and-open-sourced-ivan-owen-at-tedxrainier/ https://www.fastcompany.com/1680656/how-two-guys-got-together-to-build-a-new-hand https://www.fastcompany.com/1680656/how-two-guys-got-together-to-build-a-new-hand https://www.theverge.com/2015/3/13/8207133/3d-printed-iron-man-prosthetic-limbitless-solutions https://www.theverge.com/2015/3/13/8207133/3d-printed-iron-man-prosthetic-limbitless-solutions https://www.linkedin.com/pulse/synergistic-potential-embracing-3d-printing-op-chris-baschuk/?trackingid=7bf1k07eqxwdnudtvr%2fa1a%3d%3d https://www.linkedin.com/pulse/synergistic-potential-embracing-3d-printing-op-chris-baschuk/?trackingid=7bf1k07eqxwdnudtvr%2fa1a%3d%3d https://www.linkedin.com/pulse/synergistic-potential-embracing-3d-printing-op-chris-baschuk/?trackingid=7bf1k07eqxwdnudtvr%2fa1a%3d%3d all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives angus c. exoseketons: a rehab tech consumer’s unexpected march to action. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.2. https://doi.org/10.33137/cpoj.v4i2.37250 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.37250 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 angus c. exoseketons: a rehab tech consumer’s unexpected march to action. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.2. https://doi.org/10.33137/cpoj.v4i2.37250 stakeholder perspectives exoseketons: a rehab tech consumer’s unexpected march to action angus c.1,2* 1 chloe angus design, vancouver, bc, canada. 2 human in motion robotics, vancouver, bc, canada. introduction think about getting old. we all get older and, with aging, come arthritic knees, broken hips and other challenges. mobility challenges eventually become everybody’s problem and the solutions that are out there to help us move are like stone aged ‘sticks” (canes) and stone wheels (wheelchairs). but, times have changed and we can create something infinitely better, something revolutionary by using technology to move us beyond our physical limitations. this is not the way of the future. it is here now. cutting edge materials, 3d printing, artificial intelligence (ai), and advanced engineering can be used to create smart prosthetics, stylish orthotics, and things as futuristic as wearable robotic suits. it is technology innovation and it is my story! my name is chloë angus i am a fashion designer and mobility activist. i am the end user of ‘stone age’ mobility devices. in 2015, i had achieved the life i had always dreamt of: strolling down runways and red carpets, meeting movie stars, media personalities, politicians, and princesses. drinking bubbly for breakfast and wearing ball gowns to picnics. married for 15 years and still madly in love, my husband gabe and i had worked hard to carve out the life we wanted. i had no idea the drastic turn life was about to take. on a typical june sunday i went for a run and limped home with my right hip aching. a few hours later the toes on my right foot start tingling, going numb. i drove myself to open access volume 4, issue 2, article no.2. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract this paper is both a stakeholder perspectives as well as a ‘case study’ describing a journey from sudden disability to participant and investor in exoskeleton design. it tells of my experiences and opinions, as a successful fashion designer, when my life took a drastic turn on becoming paralysed from the waist down over the course of 24 hours, by a spinal tumour. getting this diagnosis was ‘the worst day in my life’, and it was quickly followed by the ‘second worst’ when, in my determination to walk again, i received knee ankle foot orthotics (kafos) and was shocked to learn that this appeared to be the best technology solution available on the market ‘suitable’ for use in the community. initial anger at the system for not being better, at the rehab team for their complacency, and at myself for allowing a feeling of helplessness to take over led to questions such as: what does this say about our society? and what are we all willing to accept, for ourselves and others? this is professional opinion and an essay about how we see ourselves and how others see us. the journey from pre-injury ‘consumer’ to post-injury ‘disabled’ person and learning that being labeled ‘disabled’ leads to the additional handicap of the narrow vision of “cost” taken by the mobility industry where innovative ideas are stripped down to the bare minimum with the excuse that patients are “lucky” to have what they have been “given”. grappling with these labels and inequities and seeking a better outcome, i became an integral team member of an exoskeleton development team, leading to the design of the next generation exoskeleton! this is my story, the story of chloe angus. it is the story of inclusive, user focused design and is a call to include and respect the end users of all assistive device technology design early in the design process and it is being told from the perspective of a person having experience and success in the world of business. citation angus c. exoseketons: a rehab tech consumer’s unexpected march to action. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.2. https://doi.org/10.33137/cpoj.v4i2.37250 keywords disability, rehabilitation, ankle foot orthotics, designer, fashion, handicap, exoskeleton * corresponding author chloe angus chloe angus design, vancouver, bc, canada. e-mail: chloe@chloeangus.com orcid id: https://orcid.org/0000-0002-5468-3121 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.37250 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.37250 mailto:chloe@chloeangus.com https://orcid.org/0000-0002-5468-3121 2 angus c. exoseketons: a rehab tech consumer’s unexpected march to action. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.2. https://doi.org/10.33137/cpoj.v4i2.37250 issn: 2561-987x the next generation exoskeleton angus c., 2021 cpoj special s p e c ia l i s s u e vancouver general hospital thinking: four hours to get through emergency and i’ll be back, catching up at work. unfortunately, that tingling crept up both legs and i watched helplessly as my legs stop working. 24 hours later one of the best doctors in canada told me i was paralyzed from the waist down due to a rare benign tumor in my spinal cord and i heard him say i was probably born with it. i also heard the words “loss”, “function”, “acceptance”. then that doctor, with his perfect hair and calm voice, looked me directly in the eyes and said “you will never walk again.” struggling to keep my composure, i focused on the red ferrari lanyard around his neck, thinking this isn’t possible. i was running yesterday. i drove myself to this hospital! and inexplicably i thought: how many injuries did it take to own that ferrari? and, how often does he say the words ‘you will never walk again?’ i felt the blood drain from my face, my heart tighten, and i began to envision my life in a wheelchair. a conversation in one day, i went from being a busy entrepreneur who “ran” a fashion design company to not being able to get out of a chair. over the next few weeks reality set in. i became aware of the serious secondary health complications of living in a wheelchair. muscles atrophy, bowel and bladder complications, circulation problems, pressure sores and bone density loss from not weight-bearing. then there was the extreme pain, in my case, caused by sitting too long. when my doctors offered me a fentanyl patch program for the pain i knew the world needs a better solution than the wheelchair i had. it was simply unacceptable and all of us deserve better options. this is the passion that drives me as an innovator. the circumstances leading to my losing mobility are rare, but mobility loss is more common that most people imagine. ms, parkinson’s, stroke or brain injury, along with something as simple as aging can result in the limitation or loss of mobility. so can a car accident on the way to work, or a fall on the ski hill. retirement homes and rehabilitation centers are full of wheelchairs and walkers. at some point in life, mobility becomes everybody’s problem. darkest night and the fight to keep moving that night after my doctor told me “you’ll never walk again.” (my emphasis), lying alone in my hospital room, i replayed the doctor’s words and made two important decisions. first: i would refuse to give up hope! being hopeful is not denying your reality. being hopeful is believing that nothing is impossible. armed with hope, the second decision was easy: i will not take this sitting down. i will fight for mobility. i will walk again! desperate to get back into my studio, because the fashion cycle waits for no one, i got on google and found an article in popular science magazine, about a new technology called an exoskeleton that could help paralyzed people walk again. it was a wearable robotic suit, like in the movie ironman. the next morning, i said to my husband “honey! just order me one of this off ebay and i will be back at work next week!” unfortunately, i learned, you can’t buy one on ebay. several months later at the rehabilitation centre, and after much advocating for myself, i finally was allowed to try an exoskeleton. i thought: ha! that doctor had said “you will never walk again”. he was wrong! he may have meant that i will never walk like i once did, but there are many ways to walk. what a feeling. the first time i put on the exoskeleton and walked again, after so many doctors told me i would not, was vindicating and opened my eyes to what was possible with technology. euphoric, i was ready to walk right out of the rehabilitation center. however, i quickly learned that exoskeletons, and the orthotics that go with them, were extremely limited. the device i used only allowed me to move forward in a rudimentary robotic way, not allowing for natural walking gait or balance. it also it required arm crutches and an attendant to use it. it could not be used independently or go downstairs or up curbs. the ‘orthotics’, where hard straps that pinched. visually i looked as awkward and as uncomfortable as i felt. this was clearly not a robotic suit as shown in the movies. still, the technology was amazing. it just needed to be improved. this was in 2015 and, at that time, i had no idea i would become an advocate for exoskeletons, collaborator with a tech company, or a designer of orthotics. going back in time my journey did not end with my rehabilitation or first use of an exoskeleton. weeks into my rehabilitation, i was given the diagnosis of “complete” spinal cord injury with the prognosis of “no chance of recovery”. after being able to use the exoskeleton at the rehab centre, as a result of my persistent requests and self-advocacy, i was told my time was up and the cost of my continuing to use the exoskeleton was not “worth” it. i was once again reminded that i would not recover and that i would have to learn to live my life in a wheelchair. when i persisted and told my physio team i wanted to walk again they suggested i get leg braces called kafo’s. i was made a pair, at the cost of $11,000, and the day i received them was the lowest day in my life after the day i was told i would never walk again. they looked like something out of a history book or the forest gump movie (figure 1). https://doi.org/10.33137/cpoj.v4i2.37250 3 angus c. exoseketons: a rehab tech consumer’s unexpected march to action. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.2. https://doi.org/10.33137/cpoj.v4i2.37250 issn: 2561-987x the next generation exoskeleton angus c., 2021 cpoj special s p e c ia l i s s u e figure 1: the second lowest day of my life. the day after i walked in a wearable robotic suit from the future, the rehab centre’s exoskeleton, i found myself in the basement of a hospital being fit for leg braces made of metal rods and leather straps that looked like they came out of a history book. the contradiction made me second guess my own sanity. was i in 1950? how did i get here and how do i get back to the future? re-commitment to hope: refusing to accept what i am “given” and believing ironman is possible rolling out of the orthotics dungeon, with tears in my eyes, i got mad. mad at the system for not being better, mad at my rehab team for their complacency, and mad at myself for the feeling of helplessness that i had allowed to take over. thoughts about acceptance kept coming back to me: what are we all willing to accept, for ourselves and others? mobility becomes an issue for all of us at some point in all our lives. mobility deserves advanced solutions, whether it is a simple insole that allows you to keep running well into your 90’s or a full body exoskeleton being worn by 10-yearold tetraplegic to school. society must believe in something better; believe that “ironman” is possible. but how does one shift an entire industry that seems to have become too complacent? shifting perspectives to the consumer typically, products and solutions for disabled people are designed and developed by able bodied people. worse, i learned, they are often designed to meet the needs of ablebodied people: hospitals, rehab centres, and insurance providers, those who pay the bills, are their target market. it is these bodies that typically dictate what products are made available in the mobility industry and not the people who need and use the products themselves. even worse, the actual customer, who needs the device and finds themselves in a desperate situation is made to feel they should be grateful for what they are given, even when it is often not what they need or want. the general population, including my ‘designer self preinjury’, do not know anyone in a wheelchair. that changed when i became a wheelchair user and, after just one day, it was clear my needs where not being met. almost overnight, i became an expert in a new field: the field of mobility. we can’t address what we don’t know, this is why it is so important for developers in all fields engage with those lived experts.1 my injury attached the label of ‘disabled’ on me. before that i was a ‘consumer’. as a consumer there were millions of choices offered to me. from colour to cost, brands catered to my every whim. when i shop for what i “need” now, as a ‘disabled person’ what i want is no longer offered to me as a choice. i am no longer seen as a ‘consumer’ but only as a “end-user with a disability”. this narrow vision of “cost” taken by the mobility industry is dictated by hospitals, rehab centres, and insurance providers. innovative ideas are stripped down to the bare minimum with the excuse that patients are “lucky” to have what they have been “given”. this narrow view of ‘cost’ also does not appear to consider the long-term cost of the secondary health complications a lack of mobility inflicts on individuals and the system. and it restricts those trying to come up with new solutions. if we think of cost before all else, we would not have cars, let alone people walking on the moon. as a ceo, i am well aware that costs are important factor when running a successful business, but ultimately the mobility industry needs a consumer-focused perspective shift: from patient to client if it is to grow, have market support, and ultimately happy consumers. it is always people and community, not governments, that make real change. fortunately, i found an academic team that had a similar hopeful vision for the future as i did (figure 2). the road to hope the experience of walking again, with the help of an exoskeleton was my first step to a new, technology assisted, future. no longer having access to the rehab centre exoskeleton and having found i could not order one on amazon, i started searching for access to this technology. https://doi.org/10.33137/cpoj.v4i2.37250 4 angus c. exoseketons: a rehab tech consumer’s unexpected march to action. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.2. https://doi.org/10.33137/cpoj.v4i2.37250 issn: 2561-987x the next generation exoskeleton angus c., 2021 cpoj special s p e c ia l i s s u e this led me to two engineering professors at simon fraser university in surrey, bc, canada, dr. siamak arzanpour and dr. ed park. in collaboration with them, we started human in motion robotics (hmr) and are working with a growing team of engineers, researchers, students, industry leaders, and investors to build the world’s most advanced exoskeleton for rehabilitation and personal use. the technology being developed is a radical improvement to the current technology, capable of advanced articulation and superior range of motion, allowing for natural walking, self-balancing capabilities, and independent use.2 it will allow me, and 80 million others that live with motion disabilities, to walk back into our lives with dignity and independence. the development team is working all aspects – from the technical, to orthotic fit, to focusing on practical client needs and aspirations in addition to accessibly–with the goal being that the next generation of the hmr exoskeleton will be available for purchase online and will meet the needs and wants of customers. as a designer of fashion, and now wearable and exoskeleton prototype in the lab, i envision a sleek, stylish, robotic suit in custom colours, making it “cool” to wear. people wearing our robotic suit will feel confident in the boardroom, at a cocktail party, or in their seniors’ living home. company leadership like that at hmr are to be commended by actively including those with lived experience. this approach is instrumental in making the necessary shift in the industry and creating successful markets for developed products. hope regained: my brightest day what i have described above are lofty design aspirations. my darkest day had been the night in hospital where i kept thinking about the words “you will never walk again”. many months later, and after much learning, i had one of my best, hopeful days–june 21st 2019. the day started with a highprofile client putting on a beautiful ball gown i designed with perfect fit and proportion, a vision of red silk and showcasing the skills i had developed in my years as a fashion designer. later that same day, i tried on a new “outfit” of my own, that i had also helped design, the next generation exoskeleton (figure 3). i walked independently, no attendant, no arm crutches. that was a bright day. i felt successful back in my career and – without any help or aids– i walked again! conclusion walking forward together my journey from ballgowns to wearable robotic suits has come full circle. emotionally i feel hopeful, inspired and truly alive. today, i am working on growing awareness around the issues of mobility disability and am working with, and investing in, a team of advocates and innovators– people who will take a stand for advancing technology until all mobility challenged people can ‘stand for themselves’! take a minute to envision the future of your own mobility. imagine if you become mobility impaired instead of being limited to a wheelchair, you now have options. options that will allow you to walk anywhere. you can stand to deliver a figure 2: the simon fraser university/human in motion team. persons in image have given informed consent to publication. https://doi.org/10.33137/cpoj.v4i2.37250 5 angus c. exoseketons: a rehab tech consumer’s unexpected march to action. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.2. https://doi.org/10.33137/cpoj.v4i2.37250 issn: 2561-987x the next generation exoskeleton angus c., 2021 cpoj special s p e c ia l i s s u e speech. with your exoskeleton, you will feel equal again, standing eye to eye when you shake hands. you can hug your loved ones to your chest, maybe even walk down the aisle. options that provide both physical mobility and access to the world around you. canes, walkers, and wheelchairs are not enough. we walked on the moon 50 years ago! we have the technology; all we must do is apply it. insurance and healthcare providers must get on board and those who can, should invest in advanced mobility technology for all. talk to your friends, family, and government about the need for advanced mobility. we can all be advocates. in our lifetime, people of all ages and abilities will walk again! figure 3: myself, wearing the first-generation prototype of the human in motion exoskeleton, standing on one leg independently. the harness is there just for safety, it is not supporting me. call to action • don’t make assumptions about individuals with disability. the responsibility for this relies not only on the general public and health care providers but also on tech developers and funders of health tech. get your hands dirty, get to know people with disabilities and what their aspirations are. • for the funders of health tech, calculate the quality and dignity of the experience of life into your value calculations – just like you are now taking social justice, gender and environmental (sge) criteria into account. • don’t make assumptions about what is possible. look at what has been done like sending someone to the moon and aim big. invest in a technologically improved future. the responsibility for this relies both on health and rehabilitation professionals and biomedical engineers. • advocate for the right to return to an active, integrated lifestyle and the funding investment required to both develop that necessary technology and the ability to get it to market and accessible to those who require it. the responsibility for this lies with researchers, funders, insurers and all disability advocates. • and understand that accessibility not only means that a person regains mobility and independence but that the technology required is easily accessible, from funding to on-line business models. business models in all other sectors are changing, rehab technology business models have to change with them. acknowledgements none declaration of conflicting interests chloe angus is a shareholder in human in motion research and is a member of the team developing a novel exoskeleton design. sources of support the human in motion exoskeleton is being carried out with support from the nserc engage program, the praxis spinal cord institute accelerate program, and the canadian sr&ed program. references 1.jankowski n, schönijahn l, salchow c, ivanova e, wahl m. usercentred design as an important component of technological development. curr dir biomed eng. 2017;3(1): 69-73. doi:10.1515/cdbme-2017-0015 2.sadeqi s, bourgeois s, park e, arzanpour s. design and performance analysis of a 3r rr spherical parallel manipulator for hip exoskeleton applications. rate. 2017; 5(4). doi:10.1177/2055668317697596 author scientific biography chloe angus has been a team member on an exoskeleton research team since 2017. she is an active participant in team activities, taking on the roles of end-user, design of the orthotic interface components and investor. in speaking both with team members and with investors, she is a strong advocate for including end users in tech development research in a way that listens and responds instead of limiting their voices and experience. https://doi.org/10.33137/cpoj.v4i2.37250 https://doi.org/10.1515/cdbme-2017-0015 https://doi.org/10.1177/2055668317697596 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives andrysek j. the economics of innovation in the prosthetic and orthotics industry. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.7. https://doi.org/10.33137/cpoj.v4i2.35203 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.35203 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 andrysek j. the economics of innovation in the prosthetic and orthotics industry. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.7. https://doi.org/10.33137/cpoj.v4i2.35203 stakeholder perspectives the economics of innovation in the prosthetic and orthotics industry andrysek j.1, 2 * 1 bloorview research institute, holland bloorview kids rehabilitation hospital, toronto, canada. 2 institute of biomedical engineering, faculty of applied science and engineering, university of toronto, toronto, canada. background one can appreciate the technological advancement within the prosthetic and orthotic (p&o) industry. advanced materials, body interfaces, and control systems are just some of the innovations making it possible for persons with severe disabilities such as limb loss or impairments to regain physical function and their lives. the advancement in p&o technology investment into product innovation, presumably a result of the competitive nature of the industry and desire for constant improvement of existing technologies, patient care and outcomes. advancement also responds to and affects economics, both at the health care level where technological interventions are utilized, and at the market level where products are developed and commercialized. so, what drives innovation and focuses product developers and manufacturers to tackle certain areas of technological advancements over others? are these driving forces achieving the desired goals in terms of rehabilitation care and outcomes, and if not, what is missing and what can be done? is the focus to restore the most amount of human function possible for an individual or is it to take into account economic factors and try to restore the most amount of human function of the global population that suffers from a condition? this paper aims to explore the interaction of innovation and economics of the p&o industry, focusing on the drivers of innovation including competition, technological advancement, and betterment of patient outcomes, and also the challenges including lagging clinical and cost-effectiveness evidence, research biases, existing funding structures, and the need for more inclusive models and frameworks for rehabilitation care. industry overview prosthetic and orthotic technologies are part of a large and rapidly growing medical device industry valued at over us $8 billion in canada, and over us $150 billion in the united states.1,2 the global market for prosthetics and orthotics is estimated at us $6 billion with an annual growth of nearly 5% attributed largely to a growing population in need of such treatments.3 p&o treatments (i.e. prosthetic and orthotic devices) commonly cost thousands to tens of thousands of dollars. these costs are reoccurring every several years as devices reach the end of their lifecycle, or the patient’s condition changes affecting fit and comfort, function, or desired rehabilitation goals. the process of p&o device procurement involves a number of open access volume 4, issue 2, article no.7. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract innovation is an important part of the prosthetic and orthotics (p&o) industry. innovation has the potential to improve health care services and outcomes, however, it can also be a burden to the system if misdirected. this paper explores the interaction of innovation and economics within the p&o industry, focusing on its current state and future opportunities. technological advancement, industry competition and pursuit of better patient outcomes drive innovation, while challenges in ensuring better p&o health care include lagging clinical evidence, limited access to data, and existing funding structures. there exists a greater need for inclusive models and frameworks for rehabilitation care, that focus on the use of appropriate technology as supported by research and evidence of effectiveness and costeffectiveness. additionally, innovative business models based on social entrepreneurism could open access to untapped and underserved markets and provide greater access to assistive technology. citation andrysek j. the economics of innovation in the prosthetic and orthotics industry. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.7. https://doi.org/10.33137/cpoj.v4i2.35203 keywords innovation, health care, economics, costeffectiveness, effectiveness, rehabilitation, assistive devices, technology * corresponding author jan andrysek, phd holland bloorview kids rehabilitation hospital, toronto, canada. e-mail: jan.andrysek@utoronto.ca; jandrysek@hollandbloorview.ca orcid id: https://orcid.org/0000-0002-4976-1228 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.35203 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.35203 mailto:jan.andrysek@utoronto.ca mailto:jandrysek@hollandbloorview.ca https://orcid.org/0000-0002-4976-1228 2 andrysek j. the economics of innovation in the prosthetic and orthotics industry. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.7. https://doi.org/10.33137/cpoj.v4i2.35203 issn: 2561-987x the economics of innovation andrysek j. 2021 cpoj special s p e c ia l i s s u e stakeholders, including clinicians that determine and provide the patient with the devices, funders and insurers to cover portions of the cost, and the patient with their particular rehabilitation goals. all these parties typically have some say in determining which particular device or treatment is provided. it is essential that device developers and manufacturers understand these intricacies of the health care systems when developing new products to ensure that their devices can have both a viable market and provide large scale impact on the affected populations. technology development process in p&o the p&o device industry is highly competitive. it is led by several large international corporations, each providing a variety of products. outside of commonly defined categories of products designed for a particular patient demographic or health condition, understanding the technical nuances and product differentiation can present challenges in the clinical decision-making process. hence, competing manufacturers strive for transformational advances to gain competitive advantage. such advances are often closely tied to technological advancements in other industries. for example, a leap forward in terms of strong, flexible and lightweight materials to advance foot, socket and brace designs occurred with the introduction of composites such as carbon fibre laminates in the 1980s. the 90’s which brought more powerful mobile computing, enabled the commercialization of microprocessor controlled prosthetic components such as the intelligent prosthesis from blatchford. in the 2000’s, advancements in power storage (i.e. high-density batteries) along with more powerful actuation systems have laid the foundation for powered lower-limb prostheses and exoskeletons. therefore, the adoption and adaption of scientific and technological advancements from other industries is one key driver of innovation in p&o, providing a competitive advantage to companies that invest heavily into research and development, and patients with improved rehabilitation care via access to more advanced assistive devices. the development of advanced p&o products, does not in itself ensure better health care and rehabilitation outcomes. developing useful new technology requires a design process that carefully considers and addresses the needs of the relevant stakeholders (end-user, clinicians, funders and insurers etc.). as with most medical devices, the development and commercialization of p&o technology is a complex and resource intensive process. a new p&o technology can go through many design iterations informed by modeling and empirical testing, prior to finding its place in the marketplace. r&d is typically facilitated via both academic and industry driven research, or a combination of both. government research grants typically help to fund early exploratory aspects of the r&d process. these can include industry-partnered programs which can leverage industry funds with grant money, or r&d tax credits for a company. company resources or business investment are usually needed for later-stage development, market testing and commercialization.4 established companies will typically resort to internal resources to fund product development and commercialization, while start-ups may need to raise financing through external investors (for example angel investors). occasionally, projects may in part be supported by donors or foundation grants. at the early stages, stakeholder (user, practitioner, funder, industry) involvement is essential to define the criteria for the design. methods such as the quality function deployment and the house of quality can be used to organize and prioritize design criteria.5,6 criteria can change as the development progresses and should therefore be regularly reassessed. as part of an iterative design process, simulations and prototypes can enable testing to determine how well the design works and meets the desired criteria. while these steps are essential to inform the development of the product ahead of commercialization, establishment of clinical evidence about the efficacy and effectiveness typically happens once a product is on the market. quality, effectiveness, validity the effectiveness, and more importantly cost-effectiveness, of medical interventions requires empirical clinical data, typically in the form of research-grant-funded clinical trials. clinical research informs which treatments are most useful in decreasing the burden of a health condition, and in the case of p&o decreasing the effects of the disability and improving quality of life. based on health canada and its much larger united states counterpart the food, drug, and cosmetic act (fda), prosthetics and orthotics are classified as ‘low risk’ medical devices. similarly, the sale of p&o devices in europe is subject to ce designation which is an administrative marking that indicates conformity with health, safety, and environmental protection standards. however, none of the regulatory bodies necessitate that p&o devices undergo formal testing for safety or effectiveness. bodies such as the international organization for standardization (iso) have developed standards, for example to test the strength of lower-limb prosthetic components (e.g. iso10328), however, these are not mandatory. hence, unlike other interventions including drugs, p&o manufacturers are not required to provide evidence about the safety or effectiveness of their products. however, such data can play an essential role in the clinical decisionmaking processes, allowing for more informed clinical decisions about the suitability of the treatment options available. empirical data can also play an important role in the establishment of new reimbursement codes (i.e. lcodes in the united states), thus making new devices attainable. studies demonstrating effectiveness, can further play an important role in marketing, particularly to p&o practitioners who in large part lead the purchase decisionhttps://doi.org/10.33137/cpoj.v4i2.35203 3 andrysek j. the economics of innovation in the prosthetic and orthotics industry. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.7. https://doi.org/10.33137/cpoj.v4i2.35203 issn: 2561-987x the economics of innovation andrysek j. 2021 cpoj special s p e c ia l i s s u e making process. cost-effectiveness analyses, which compare treatments and their relative costs and outcomes, enable funders, governments and health care professionals and institutions, to make informed decisions about the care that is provided within funding constrained health care systems.7 unfortunately, the clinical evidence relating to most p&o interventions is lacking or is not of high quality. the highest evidence comes from meta-analyses of rcts (level 1), followed by at least one rct (level 2), quasi experimental designs (level 3) and so on, and the majority of clinical research studies involving p&o interventions fall in the latter categories.8 the customization of aspects of the p&o treatments, heterogeneity of patient populations, broad range of technologies and products, as well as varying patient goals and outcome measures, are just some of the challenges in designing quality research studies. methodological issues, such as the inability to apply double blinding to the intervention (for example, participants or prosthetists can not readily be blinded when testing prosthetic knees that have distinct function or instructions for use), introduce potential study biases, compromise the resulting evidence, and fail to fully uphold the accepted methodological standards of rcts. availability and ability to attain funding for clinical studies is also a significant challenge. a typical multi-year rct can easily cost $500,000 or more. in p&o, the high cost of componentry can further increase required funding, and thus may not be viewed favourably by grant review committees and dismissed as not being an effective use of grant/tax-payer monies. in canada, funding for clinical trials would typically be sought from canadian institutes of health research (cihr). cihr grant applications are extremely competitive, and p&o is up against a broad range of other healthcare priorities, such as finding the cure for cancer, which has relevance to a much larger part of our population. hence, p&o researchers commonly resort to applying for smaller grants, which limits the types of studies and quality of clinical evidence. possibly due to aforementioned restrictions in accessing traditional grant funding, many studies evaluating p&o products are sponsored by companies selling the products. while this may be a means for establishing studies and providing at least some evidence, the data may be potentially susceptible to biases, or at least a perception thereof.9 there is little incentive for a company to disseminate results that do not demonstrate their product to be superior and bring the anticipated benefits. with higher level studies including registered clinical trials, there exist greater oversights for unbiased reporting of results; unfortunately, in p&o such studies are not common. another major challenge is the latency in establishing clinical evidence. for example, microprocessor knee joints were introduced to the market in the mid 1990’s, however, to this date, evidence is based on not one rct.10 these limitations make it challenging for stakeholders to know which innovations truly serve the needs of the patient and health care system. while many innovations improve our lives, some may bring undesired adversities, complexities and disenchantment. for example, despite the advancements in electromechanical prostheses including myoelectric hands, much simpler purely mechanical body-powered devices are still highly utilized in clinical care.11 some of this is attributable to the high cost of myoelectric devices, but also likely their limited function and utility. with most health care expenditures being contained, innovation can be a major inflationary factor, and the high cost of p&o treatments requires especial consideration of cost-effectiveness. for example, while microprocessor knee joints are shown to provide benefits including the reduction of falls, their acquisition and maintenance costs are significantly higher than their mechanical counterparts.7,10 many public health care systems do not fully cover the cost of p&o devices, and especially those at the higher end of technological sophistication. as such, significant inequalities exist in terms of access to modern innovations typically costing significantly more than the status quo. these discrepancies are apparent in places like canada, where clinical provision of high-end p&o technology is far from universal.12 even more striking, 85% of the world’s disabled population lack access to even the most basic p&o interventions.13 while this immense problem is not solely due to the lack of costeffective devices, it nevertheless suggests that our efforts to innovate may be to some extent misguided.14 future directions innovation is most commonly associated with the advancement of sophisticated p&o technology, however, could and should more of our energies be directed elsewhere? should we, for example, focus on the development of technology that is simpler, more costeffective, and still adequately functional? such an approach could potentially achieve greater equality and access to p&o devices. perhaps the focus should be less on the promotion of sophisticated devices, and more at taking measures to study and ensure that a device is appropriate for its application. for this, research needs to step beyond simply assessing select aspects of device performance under laboratory conditions, and towards more real-life and comprehensive assessments that capture what is truly important to the person using the device, as well as the health care system.15 greater understanding yet, is needed in evaluating the quality of life outcomes and costeffectiveness of p&o care and devices. finally, a greater understanding, which could be obtained via research, is needed about the factors including technological, economic, healthcare, cultural, demographic, regulatory aspects, that drive the care and devices that are provided. currently, the https://doi.org/10.33137/cpoj.v4i2.35203 4 andrysek j. the economics of innovation in the prosthetic and orthotics industry. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.7. https://doi.org/10.33137/cpoj.v4i2.35203 issn: 2561-987x the economics of innovation andrysek j. 2021 cpoj special s p e c ia l i s s u e available information is anecdotal at best. establishment of data in these respects could help in the development of new frameworks and approaches for the provision of assistive technology, concomitantly targeting greater access, better outcomes, and higher efficiency.16 innovative approaches to service and device delivery have had significant impact in other areas of health care to provide greater access to quality care. in the 1980’s, for example, the high cost of implantable intraocular lenses (iol) restricted access to cataract surgery amongst the poor in india. this led to the development of new manufacturing facilities, capable of producing iols at a small fraction of the market price.17 lower price not only enables greater access, but also increases sales, which in turn increases manufacturing output and efficiencies. innovative new industry entrants can therefore disrupt the competition and in this particular case the iol venture was able to significantly increase access to iol and cataracts surgery. the innovative approach established in the iol industry also included a hybrid business model, focused on sustainable business operations while in parallel serving a social mission to provide greater access. similar models have been demonstrated in p&o, however greater initiative is needed by companies, for example, legworks inc, and organizations with a strong presence and influence in the market.18 alternatively, greater focus on training the next generation of social entrepreneurs with a focus on p&o, could help to establish innovative and more inclusive models and frameworks for rehabilitation care to advance promising ongoing efforts involving various organizations and partnerships.16,19-21 moreover, serving to the needs of the less-resourced markets, as hybrid models aim to do, could in turn drive the development of cost-effective and affordable p&o devices, as opposed to the current status quo where low cost devices are typically of low function and in some cases lower quality. call to action much like the human body, the p&o industry is an amazingly complex system. technological ingenuity has allowed assistive devices to successfully restore the body’s function for those that have access to such technology. the p&o industry can and should take certain steps to ensure that rehabilitation care reaches all those that need it. organizations such as the international society of prosthetics and orthotics (ispo) need to take a leadership in identifying and defining p&o priorities through engagement and consensus of stakeholders and industry experts many of whom are members of ispo. in this way ispo and other professional organizations can help to inform and advocate around the pressing issues towards a focused action plan. consensus of priorities will provide a stronger and more justifiable foundation for researcher to build competitive funding applications. recent initiatives and reports developed by the clinton health access initiative (chai) under the at2030 programme in support of the at-scale strategy are an excellent example of such an effort. for the p&o industry specifically, there now exists a comprehensive globally relevant narrative identifying the barriers and exploring ways for better p&o service delivery.16 such works could similarly help to structure and prioritize research and development efforts. as such, a greater understanding of the workings of the p&o industry could help to identify the gaps and opportunities to truly advance p&o care. focusing a greater part of innovation on simpler technology and using empirically derived evidence to inform its use in clinical care, could also help ensure that appropriate technology is utilized. there needs to be more incentive for companies in this regard. internally, companies can decide to uphold a greater focus on what might be less profitable but more impactful projects and products, for example by having a social for-profit business structure focused on developing and providing affordable, appropriate and high-quality prosthetic components within both highand low-income countries. innovative business models based on social entrepreneurism could open access to untapped and underserved markets, thus making social entrepreneurism a viable, sustainable and potentially profitable approach for companies. it may be possible to adapt and scale the examples of iol and legworks inc as described above. however, governments also have a role to play since to an extent they dictate what products are lucrative to develop and sell in the presiding healthcare ecosystems. in the united states, the reimbursement codes and categories are largely based on the technical features of a device, rather than a metric of performance. this is likely in part due to the fact that performance measures require clinical evidence, which as described previously is greatly lacking in p&o. additionally, in markets such as the united states, existing reimbursement systems favour high-end devices which yield greater margins for the clinics and companies selling components. hence governments play an important role in managing these aspects of the medical device industry. government also provides research funding and sets scientific priorities. a greater level of communication and coordination is needed amongst different industry stakeholders, including patients, clinicians, healthcare institutions, professional organizations, companies, academia, and government to identify and tackle the key priorities, such as the generation of data relating to cost-effectiveness for informing governmental policy, and establishing the proper funding systems and rehabilitation health care services. such efforts need to be driven by organizations that are comprised of representation from all of the stakeholders, such as ispo at the international level, and locally with organizations such as orthotics prosthetics canada (opc) or american orthotic & prosthetic association (aopa) in the united states. for the common goal of all of the https://doi.org/10.33137/cpoj.v4i2.35203 5 andrysek j. the economics of innovation in the prosthetic and orthotics industry. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.7. https://doi.org/10.33137/cpoj.v4i2.35203 issn: 2561-987x the economics of innovation andrysek j. 2021 cpoj special s p e c ia l i s s u e stakeholders in the p&o industry should be clear, and that is to provide equitable access to p&o care, and to enable individuals to successfully rehabilitate. acknowledgements i would like to thank brandon burke for the discussions that helped to formulate the direction and ideas for this paper, as well for his feedback and edits declaration of conflicting interests jan andrysek is a co-founder and active member of legworks inc. he is also a member of exceed worldwide and ispo. sources of support none. references 1.canada – overview of medical device industry and healthcare statistics [internet]. emergo by ul, 2021; [cited 2021 january 4]. available from: https://www.emergobyul.com/resources/marketcanada 2.u.s. medical device market reaches $156 billion mark [internet]. [cited 2020 november 30]. available from: https://www.prnewswire.com/news-releases/us-medical-devicemarket-reaches-156-billion-mark-300805696.html 3.prosthetics and orthotics market size, share & trends analysis report by type orthotics (upper limb, lower limb, spinal), prosthetics (upper extremity, lower extremity), and segment forecasts, 2020 – 2027 [internet]. [cited 2020 november 30]. available from: https://www.grandviewresearch.com/industry-analysis/prostheticsorthotics-market 4.de pouvourville g. innovation as a major research issue in health economics. eur j heal econ 2001; 2: 139–141. 5.einspruch em, omachonu vk, einspruch ng. quality function deployment: application to rehabilitation services. int j health care qual assur 1996; 9: 42–47. doi: 10.1108/09526869610117766 6. marson e, sartor m. quality function deployment (qfd), sartor, m. and orzes, g. (ed.) quality management: tools, methods, and standards, emerald publishing limited, bingley. 2019; 77-90. doi:10.1108/978-1-78769-801-720191005 7.kuhlmann a, krüger h, seidinger s, hahn a. cost-effectiveness and budget impact of the microprocessor-controlled knee c-leg in transfemoral amputees with and without diabetes mellitus. eur j heal econ. 2020; 21(3):437-49. doi: 10.1007/s10198-019-01138y 8.ackley b, ladwig g, swan ba, tucker s. evidence based nursing care guidelines. medical surgical interventions. mosby elsevier, syf. 2008;15. 9.ayorinde aa, williams i, mannion r, song f, skrybant m, lilford rj, et al. assessment of publication bias and outcome reporting bias in systematic reviews of health services and delivery research: a meta-epidemiological study. plos one. 2020;15(1):e0227580. doi: 10.1371/journal.pone.0227580 10.mileusnic mp, rettinger l, highsmith mj, hahn a. benefits of the genium microprocessor controlled prosthetic knee on ambulation, mobility, activities of daily living and quality of life: a systematic literature review. disabil rehabil: assist technol. 2019; 1-2. doi: 10.1080/17483107.2019.1648570 11.resnik l, borgia m, cancio j, heckman j, highsmith j, levy c, et al. dexterity, activity performance, disability, quality of life, and independence in upper limb veteran prosthesis users: a normative study. disabil rehabil. 2020; 1-12 doi: 10.1080/ 09638288.2020.1829106 12.martin d, miller ap, quesnel-vallée a, caron nr, vissandjée b, marchildon gp. canada’s universal health-care system: achieving its potential. lancet. 2018; 391(10131):1718-35. doi: 10.1016/ s0140-6736(18)30181-8. 13.who standards for prosthetics and orthotics. part 2: implementation manual [internet]. world health organization, 2017; [cited 2021 january 4]. available from: https://apps.who.int/iris/bitstream/handle/10665/259209/97892415 12480-part2eng.pdf;jsessionid=e360e596e0866257a26b5af9364dd895?se quence=2 14.who standards for prosthetics and orthotics, part 1: standards [internet]. world health organization, 2017; [cited 2021 january 4]. available from: https://apps.who.int/iris/bitstream/handle/10665/259209/97892415 12480-part1-eng.pdf 15.andrysek j. lower-limb prosthetic technologies in the developing world: a review of literature from 1994-2010. prosthet orthot int. 2010; 34: 378–398. doi: 10.3109/03093646. 2010.520060 16.product narrative: prostheses a market landscape and strategic approach to increasing access to prosthetic devices and related services in low and middle income countries [internet]. [cited 2021 january 4]. available from: https://static1.squarespace.com/static/5b3f6ff1710699a7ebb6449 5/t/5f75fe9a9993bf06c4e0ef21/1601568464902/pn_prostheses_ a11y_final.pdf 17.aravind eye hospitals. wikipedia [internet]. [cited 2020 november 30]. available from: https://en.wikipedia.org/wiki/aravind_eye_hospitals#aurolab 18.legworks [internet]. [cited 2020 november 30]. available from: https://legworks.com/ 19.swisslimbs [internet]. [cited 2020 november 30]. available from: http://www.swisslimbs.org/ 20.international committee of the red cross, icrc, physical rehabilitation 2018 annual report [internet]. [cited 2021 january 4]. available from: https://shop.icrc.org/physical-rehabilitationprogramme-2018-annual-report-pdf-en 21.exceed worldwide [internet]. [cited 2020 november 30]. available from: https://www.exceed-worldwide.org/ https://doi.org/10.33137/cpoj.v4i2.35203 https://www.emergobyul.com/resources/market-canada https://www.emergobyul.com/resources/market-canada https://www.prnewswire.com/news-releases/us-medical-device-market-reaches-156-billion-mark-300805696.html https://www.prnewswire.com/news-releases/us-medical-device-market-reaches-156-billion-mark-300805696.html https://www.grandviewresearch.com/industry-analysis/prosthetics-orthotics-market https://www.grandviewresearch.com/industry-analysis/prosthetics-orthotics-market https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part2-eng.pdf;jsessionid=e360e596e0866257a26b5af9364dd895?sequence=2 https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part2-eng.pdf;jsessionid=e360e596e0866257a26b5af9364dd895?sequence=2 https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part2-eng.pdf;jsessionid=e360e596e0866257a26b5af9364dd895?sequence=2 https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part2-eng.pdf;jsessionid=e360e596e0866257a26b5af9364dd895?sequence=2 https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part1-eng.pdf https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part1-eng.pdf https://static1.squarespace.com/static/5b3f6ff1710699a7ebb64495/t/5f75fe9a9993bf06c4e0ef21/1601568464902/pn_prostheses_a11y_final.pdf https://static1.squarespace.com/static/5b3f6ff1710699a7ebb64495/t/5f75fe9a9993bf06c4e0ef21/1601568464902/pn_prostheses_a11y_final.pdf https://static1.squarespace.com/static/5b3f6ff1710699a7ebb64495/t/5f75fe9a9993bf06c4e0ef21/1601568464902/pn_prostheses_a11y_final.pdf https://en.wikipedia.org/wiki/aravind_eye_hospitals#aurolab https://legworks.com/ http://www.swisslimbs.org/ https://shop.icrc.org/physical-rehabilitation-programme-2018-annual-report-pdf-en https://shop.icrc.org/physical-rehabilitation-programme-2018-annual-report-pdf-en https://www.exceed-worldwide.org/ 6 andrysek j. the economics of innovation in the prosthetic and orthotics industry. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.7. https://doi.org/10.33137/cpoj.v4i2.35203 issn: 2561-987x the economics of innovation andrysek j. 2021 cpoj special s p e c ia l i s s u e author scientific biography dr. jan andrysek is a senior scientist at the bloorview research institute of holland bloorview kids rehabilitation hospital. he is also an associate professor at the institute of biomedical engineering, university of toronto. his research program focuses on the development of treatments and assistive technologies for children and youth with disabilities. specific areas of study include prosthetic and orthotic limb control, bio sensing and biofeedback systems, and instruments to measure assistivetechnology-facilitated mobility and physical activity in real-life environments. current research is also focused on understanding the global need for prosthetic technology, and impact on mobility, physical function, and quality of life. he is the recipient of awards including the 2017 ontario profession engineers engineering medal for research and development, clifford chadderton award for prosthetics and orthotics research, and first price at the 2015 accessibility innovation showcase tech pitch competition sponsored by the government of ontario. in 2019 dr. andrysek was elected an american institute for medical and biological engineering (aimbe) fellow. dr. andrysek is also the co-founder and chief scientific officer at legworks inc., a social for-profit enterprise focused on improving prosthetic technologies and care for individuals with amputations worldwide. https://doi.org/10.33137/cpoj.v4i2.35203 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 research article walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.36065 1 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 research article clinical outcome of transfemoral direct socket interface (part 2) walker j1, marable w.r2,3, smith c3, sigurjónsson b.þ3, atlason i.f4, johannesson g.a5 * 1 virginia prosthetic & orthotics, roanoke, virgina, usa. 2 össur hf, foothill ranch, california, usa. 3 össur hf, reykjavik, iceland. 4 quick lookup, reykjavik, iceland. 5 teamolmed, stockholm, sweden. introduction the primary goal for people that have undergone lower limb amputation is to return to the main activities of daily living, including recreational and professional activities.1 transfemoral (tf) amputation and the subsequent loss of knee function is known to negatively impact prosthetic fitting, functional outcome, and quality of life (qol), as compared to transtibial amputation.2-7 persons with tf amputation face significantly more challenges when receiving a prosthesis for the first time. with more days spent in rehabilitation, the functional outcome and qol are still lower at the time of discharge compared to persons with transtibial (tt) amputation.7-11 additionally, the certified prosthetist (cp) faces a more significant challenge in fitting tf patients versus tt patients.3,12 tf amputations may account for approximately 40% of all lower-limb amputations in the us alone and result in a twofold higher mortality rate than after tt amputations13 and a lower rate open access volume 4, issue 1, article no.6. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: amputation at the transfemoral (tf) level reduces the rate of successful prosthetic fitting, functional outcome, and quality of life (qol) compared with transtibial amputation. the tf socket interface is considered the most critical part of the prosthesis, but socket discomfort is still the most common user complaint. direct socket for transfemoral prosthesis users is a novel interface fabrication process where the socket is shaped and laminated directly on the residual limb and delivered in a single visit. objective(s): the aim of this study was to investigate if prosthetic users' quality of life (qol), comfort, and mobility with a direct socket tf interface were comparable to their experience with their previous prostheses. methodology: the pre/post design prospective cohort study included 47 subjects. from this cohort, 36 subjects completed the 6-months follow-up (mean age 58 years, 27 males). outcomes at baseline included eq-5d-5l®, plus-m™, class, abc, amppro, and tug. at 6-weeks and 6-months, subjects repeated all measures. seven certified prosthetist (cp) investigators performed observations and data collection at six different sites (from july 2018 to april 2020). findings: results showed significant improvement in all outcome measures for the 36 subjects that completed both 6-weeks and 6-months follow-ups. class sub-scales showed significantly improved stability, suspension, comfort, and socket appearance. improvement in k-level and less use of assistive devices were observed with the amppro instrument, indicating improved user mobility and performance. qol was also increased, as measured in quality-adjusted-life-years (qaly) from the eq-5d-5l. conclusion: evidence from the findings demonstrate that the direct socket tf system and procedure can be a good alternative to the traditional method of prosthetic interface delivery. article info received: february 19, 2021 accepted: may 26, 2021 published: june 8, 2021 citation walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i 1.36065 keywords transfemoral amputation, health, amputee, prosthesis, socket, interface, comfort, outcome measure, satisfaction, direct casting * corresponding author g. anton johannesson, phd teamolmed, kistagången 12, 164 40 kista, stockholm, sweden. e-mail: ajohannesson@teamolmed.se orcid: https://orcid.org/0000-0001-8729-458x https://doi.org/10.33137/cpoj.v4i1.36065 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.36065 https://doi.org/10.33137/cpoj.v4i1.36065 mailto:ajohannesson@teamolmed.se https://orcid.org/0000-0001-8729-458x 2 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 issn: 2561-987x transfemoral direct socket interface walker et al. 2021 cpoj of prosthetic fitting.5 also, unfortunately, most cps have less experience fitting tf amputees; thus, outcomes and proficiency are diminished.14 moreover, tf interfaces are researched less frequently than tt interfaces. therefore, cps have less published evidence to guide their practice.12 a meager body of published evidence surrounds tf interfaces, and most lack methodological quality. investigations assessing the advantages and disadvantages of available socket designs are few and lack randomized controls.12 the heterogeneity of intervention, study population, and outcome measures make metaanalysis impossible.3,12,14,15 the tf socket interface, considered the most important part of the prosthesis, allows the user to control the prosthesis and provides pelvic stabilization during loading. the ischial ramus containment (irc) socket claims to feature a "bony lock" believed to be most effective during full stance phase. the "bony lock" is defined as a 3-point support between the femoral shaft, the ischium, and a high medial and lateral socket trimline.16 while we can observe anecdotally that many patients succeed with such socket designs, only theoretical models and limited evidence exist to support 3point support efficacy.17 despite limited evidence, the "3point support" sockets enjoy wide popularity, and many western countries consider them the standard of care, especially for active users. however, based on different functional philosophies, alternative socket designs are available. performance can be retained, and comfort increased while abandoning or altering the 3-point support.17-19 furthermore, traditional fabrication and delivery of tf interfaces often involve multiple client visits to the prosthetic clinic for casting or scanning, diagnostic interface (or "check socket") fittings and modifications, definitive laminated interface fabrication, and final fitting and delivery.2,11,20 the user then returns as needed for adjustments and modifications mostly related to comfort and functional issues. it is understood that the sooner a patient can begin gait training with their definitive socket, the better.21,22 the direct socket tf (ds-tf) enables a prosthetist to fabricate a custom-made interface directly on the residual limb in a single visit, similar to direct socket tt.23 the proximal portion of a ds-tf interface design differs from the proximal portion of sockets, typically included in the above described irc sockets designs,16 as the proximal part of the ds-tf incorporates a size-specific silicone brim instead. the support provided by the ds-tf brim activates and stimulates important hip muscle function24 to enable loading and axial/transverse stability during normal walking.23 the unique ds-tf interface design has led to greater user satisfaction regarding interface function, comfort, and overall improvement in the fabrication and delivery experience compared to traditional methods.25-27 a deeper analysis of the outcome requires more specific tools.12 dissonance between the user and the prosthetic interface design can negatively impact comfort level and strongly correlates with lower functional outcomes.14 it often leads to increased residual pain, phantom pain,28 restricted movement,29 dermatological problems, or a combination of those,30 most often related to the proximal trimline and lack of femur stability and positioning. historically the use of selfreport instruments has not been the standard in daily practice, but the prevalence of their application has been increasing.31,32 cps are improving their implementation of such instruments to help screen amputees for prosthetic fitting candidacy and monitor mobility and comfort outcomes.33 responses facilitate communication between the prosthetic user and clinician, inform training decisions, and evaluate care efficacy.34,35 cps have access to selfreport instruments, specifically applicable to tf prosthetic users that measure health outcomes, socket comfort, and mobility. combining self-report and performance-based evaluation measures reveals a comprehensive picture of overall function. this type of detailed data is increasingly used to inform healthcare policies and payments.36 this paper investigates if ds-tf direct lamination,25 in contrast to traditional plaster casting and 3d scanning techniques, can result in similar outcomes for the end-user. in this way, using plaster or foam model intermediates, that are only an approximation of the limb shape, are eliminated. we compared the new ds-tf interface versus the existing traditional socket using two modules from the orthotics and prosthetics 'user's survey (opus) in the first article on this study.27 this paper, aiming to build on the previous publication, quantifies different subjective and objective outcomes using instruments applicable to this specific population of prosthetic users. methodology between july 2018 and october 2019, seven cps in six prosthetic clinics across the united states implemented a new prosthetic interface for transfemoral prosthesis users. in total, 47 subjects were enrolled into this study. the previous article was derived from the same cohort27 and includes detailed descriptions of principal investigator selection criteria, practitioner/clinician training, implementation process, and interface design. the inclusion criteria (rationale) were as follows: • 50kg<bodyweight<166kg (the iso validated weight limit of the ds-tf) • cognitive ability to understand all instructions and questionnaires in the study • patients who have undergone a tf amputation>1 year post-amputation (this was to avoid https://doi.org/10.33137/cpoj.v4i1.36065 3 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 issn: 2561-987x transfemoral direct socket interface walker et al. 2021 cpoj postoperative problems and/or adjustments related to the initial prosthetic fitting of a new amputee) • willing and able to participate in the study and follow the protocol • circular dimension of 40-65 cm at the crotch (limited to available silicone brim sizes) • residual limb length at least 20 cm from ischium to the distal end (fabrication limitation of the dstf) • currently using a prosthetic liner (this was to avoid potential confounding influence from transitioning an amputee from a skin fitting interface (i.e., without a liner) to an interface with a liner) ethical approval was obtained from advarra® irb (cr00128417), and the investigation was registered at clinical trials.gov nct04312724. signed informed consent was obtained from all participants. all study subjects completed the baseline measurements related to their current prosthesis (figure 1). each subject was consequently fitted with ds-tf by one cp with one technician's assistance. two subjects received a new knee and foot with the new interface. manufacture and features of the ds-tf during the fabrication process, a specific casting liner is rolled onto the residual limb, followed by application of a protective silicone sheath. next, the cp places a sizespecific silicone brim at the proximal part of the limb. a fiberglass or basalt fabric with a pre-attached 4-hole distal adapter is then rolled on the length of the limb. an additional protective sheath is applied on the outside of the fabric, and a two-part resin is injected through the distal adapter. the resin saturates the fiber, and then it hardens and cures. after 10-15 minutes it has cured enough to be removed. finally, the socket is prepared to be connected to their knee and foot.25,26 the brim is made of flexible silicone and laminated to the socket during this process, making the socket flexible proximally, while most of the socket is rigid. the flexible silicone brim encompasses and compresses the proximal thigh muscles when contracted, thereby stabilizing the hip at initial contact, loading response, mid-stance, and terminal-stance while creating axial and transverse stabilization.27 during swing phase, the brim only follows the hip movement. outcome measures and data collection each prosthesis user completed two parts of the orthotics and prosthetics user's survey (client satisfaction with device (opus csd) and client satisfaction with services (opus css)) for evaluating the new interface and the service model. additional data was collected using multiple standardized outcome measures, including: • four subjective self-evaluation measures: health status; perceived mobility level; satisfaction regarding socket stability, suspension, comfort, and appearance; and confidence regarding balance and perceived risk of falls. • two objective performance measures. figure 1: flow chart of the trial. most outcome measures (plus-m™,37 class,38 abc,39 tug,40 and amppro41) were collected using the prosthetic rehabilitation outcomes application (proapp) ipad application. two measures were collected using paper forms (eq-5d-5l® and opus). the proapp systematically helps the clinician gather and securely store subjective and functional outcomes data. drop out before six-weeks (n=7) • one amputee died • four amputees went back to their previous interface • one due to severe vascular problems (not device related) • three due to poor m-l stability (compared with existing interface) • two lost to follow-up (one still using the new interface) at six-months follow-up (6mfu), n=36 subjective and objective evaluations measurement used: subjective: eq-5d-5l ® , plus-m™, class, (*opus-csd and css), abc objective: tug, amppro * analysed in the previous article 27 subjects enrolled into the study (baseline), n=47 subjects completed self-evaluation measures with their existing socket, including subjective and objective evaluations measurement: subjective: eq-5d-5l®, plus-m™, class, abc, (*opus-csd and css), objective:tug and amppro after fitting with direct socket tf, subjects completed class and tug * analysed in the previous article 27 drop out at six-month (n=4) • one amputee went for additional surgery on the contralateral side (still uses the new interface) • one lost from follow-up (still using the new interface) • two missing data at six weeks follow-up (6wfu), n=40 subjective and objective evaluations measurement used: subjective: eq-5d-5l ® , plus-m™, class, (*opus-csd and css), abc objective: tug, amppro * analysed in the previous article 27 https://doi.org/10.33137/cpoj.v4i1.36065 4 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 issn: 2561-987x transfemoral direct socket interface walker et al. 2021 cpoj the proapp also helps with clinical care decisions, communication with referral sources, physical therapy, and validating prosthetic care to payor sources.42 table 1 contains full description of the outcome measures used. outcome measures were collected on each subject at three time periods: baseline, 6-weeks post fitting, and 6-months post fitting. subject completed class, plus-m, abc, amppro, opus, eq-5d, and tug using their existing socket. on the day of fitting, subjects completed tug (as an objective measurement) and class (as a subjective measurement) with their new ds-tf interface (figure 1). subjects returned to repeat class, plus-m, abc, amppro, opus, eq-5d, and tug six weeks after fitting and then again six months after fitting. the goal was to collect 940 datasets: meaning every subject (n=47) completed 20 outcome measurements in total over the six months. sample size and statistical methods we conducted a pretrial power analysis for the estimated required sample size using gpower version 3.1.9.650 and estimated effect size based on published articles7,51,52 for the primary endpoint assuming a normally distributed amputee population. therefore, we expected that 38 subjects were required to complete the protocol with a power of 0,95 and α at 0,05. we estimated the drop-out rate to be 20%, and therefore, 47 subjects were recruited. • eq-5d-5l®: a valid and reliable questionnaire to describe and value health. the descriptive system comprises five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. each dimension has 5 levels: o no problems, slight problems, moderate problems, severe problems and extreme problems. the patient is asked to indicate his/her health state by ticking the box next to the most appropriate statement in each of the five dimensions. this decision results in a 1-digit number that expresses the level selected for that dimension. the digits for the five dimensions can be combined into a 5digit number that describes the 'patient's health state. this health state is then an indicator of the utility of the patient. one of the values that can be derived from eq-5d-5l® is quality-adjusted life-year (qaly).43 the mean (standard deviation) utility value for the us population in 2020 was estimated to be 0.85 (sd=0.21).43 qalys can be used to evaluate the efficacy of one healthcare intervention versus another. qaly can be used to guide patients and providers to prosthetic solutions that maximize qol increases while also implementing efficient fitting processes and using healthcare funds responsibly.44 • plus-m™: the prosthetic limb users survey of mobility (plus-m™) measures perceived mobility and was developed for lower limb prosthesis users. the survey includes 12 questions that assess mobility with a prosthetic leg and are answered on a five-point scale ranging from "unable to do" the activity, to able to do the activity "without any difficulty". a higher plus-m™ t-score corresponds to greater mobility. plus-m™ t-scores are referenced to the plus-m™ development sample (n=1091 lower limb prosthesis users). a t-score has a mean of 50 and a standard deviation of 10. a plus-m™ t-score of 50 represents the mean mobility reported by the development sample. a respondent that receives a t-score of 60 has reported a level of mobility approximately 1 standard deviation above the mean. conversely, a respondent that receives a t-score of 40 has reported their mobility to be about one standard deviation below the mean.45 • class: the comprehensive lower-limb amputee socket survey is a newly developed outcome measurement tool. it reports measures regarding the function of the prosthetic interface (e.g., the socket) that is composed of 15 items. the first five context items are scored using a 4-point likerttype scale with response options and the corresponding point value of: strongly disagree (1), disagree (2), agree (3), and strongly agree (4). the last item of every determinant addressed the overall satisfaction and was scored using a numerical rating scale with values ranging between 0 and 5 points. the maximum possible score for each of the four determinants was 25 points. the class score for each subscale is then represented on a 0%–100% scale (with 100% indicating excellent satisfaction). the average overall socket satisfaction including all levels (ankle, transtibial, knee and transfemoral) of the class, administered measured on 124 lla, was found to be for stability 70% (sd=18), suspension 71% (sd=19), comfort 69% (sd=20) and appearance 58% (sd=22).15 • abc: activities based confidence indicator quantifies 'individuals' confidence in their ability to perform 16 activities of daily living by rating confidence from 0% (no confidence) to 100% (complete confidence) for each activity. the scores for each of the activities are averaged to obtain a total score.46 in a study by miller et.al., the mean score was 63.8. for subjects amputated due to vascular reasons, it was 54.1 and 74.7 for subjects with amputation due to non-vascular reasons.39 • *opus: the opus (orthotics and prosthetics 'user's survey) is a set of self-reported outcome measures to be used within o&p clinics for the assessment of functional status, quality of life, and client satisfaction and was used in the previous article. 27 the opus instrument consists of five independent modules, two of which were used in this study: client satisfaction with device (csd) and client satisfaction with services (css). the csd and css include a total of 21 questions, scored on a 16, discrete scale: strongly agree, agree, neither agree nor disagree, disagree, strongly disagree and don't know/not applicable.47 different authors have used scoring for opus in a different way, so there is no minimal or maximal score reported. the mean score reported by jarl et.al. for csd was 36.5 and for css was 55.7 on a us sample of 126 prosthetic users (all levels).48 performance-based (objective) outcome measurements were: • tug: the timed up and go test is a test where the prosthetic user performs the test by standing up from a chair, walking ten feet, turning and returning to the chair, and then sit on the chair. this measure tests a number of tasks that are essential for mobility, such as standing from a seated position, walking, turning, and sitting down on the chair, and can be used with or without walking aid. a lower limb prosthetic user who takes ≥19 seconds to complete the tug indicates an increased risk of fall.49 • amppro: this clinical tool is designed for assessing an amputee 'subject's mobility and for assessing existing or potential functional ambulation of the lower-limb amputee. it consists of 21 tasks, classified into four categories: sitting balance, simple mobility, standing balance, and gait and functional activities. the total score ranges from 0 to 47 points. higher scores indicate better mobility.41 the normative data for lower limb amputees has been established according to the k levels classification with the five categories ranging from k level 0 (least mobile/not using prosthesis) to k level 4 (most mobile) intended to indicate a 'person's rehabilitation potential,35 using the amppro score. the normative values of amppro for each of the k levels classification have been set to: • k1 = amppro 15-26, k2 = amppro 27-36, k3 = amppro 37-42,k4 = amppro 43-47 *included in previous article 27 table 1: full description of the outcome measures used in this study. https://doi.org/10.33137/cpoj.v4i1.36065 5 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 issn: 2561-987x transfemoral direct socket interface walker et al. 2021 cpoj we used r version 4.03 (r-studio version 1.2.5033) and lme4.53 we performed linear mixed-effects analyses of the relationship between outcomes and clinical need (defined as users who needed a replacement prosthetic interface, according to new referral, due to wear and tear or volume changes) and those with no clinical need of replacement. as fixed effects, we entered age, gender, and evaluation point (tested for interaction with clinical need) into the model. as random effects, we included intercepts for subjects and investigators and by-subject and by-item random slopes for the effect of clinical need. p-values were obtained by likelihood ratio tests of the full model with the effect in question against the model without the effect. results the subjects, with a mean age of 59 years (36-79 years) when entering the study, 33 men and 14 women prosthesis users, represented a wide range of activity levels (figure 2). of the initial cohort, 36 participants completed the entire 6month follow-up (6mfu; 27 men and 9 women: mean age 58.2 years (38-81 years). nine subjects dropped out of the study: 7 at or before 6-week follow-up (6wfu; including one deceased) and 2 before 6mfu (figure 1). one subject with advanced vascular disease and a small limb withdrew after one week. three subjects withdrew, preferring their previous socket. two subjects in the "clinical need" subgroup did not complete all measurements at the three time periods and therefore were not included in further data analysis at 6mfu. one subject became non-ambulatory for a portion of the study for reasons unrelated to the prosthesis. though he was considered a drop-out, he continued to use the new interface after the study ended. three subjects didn't come in for follow-up measurements. at least two of them continued to use the new ds-tf interface. all subjects used a liner with their interface. a description of their prosthesis can be found in the previous study.27 subjects represent the full spectrum of k-levels 1 through 4: • k-level 1, n=4 • k-level 2, n=11 • k-level 3, n=21 • k-level 4, n=11 upon inclusion, participants were classified into two subgroups: subjects with a "clinical need" of socket replacement and subjects with "no clinical need", as determined by their cp. the mean age of the "clinical need" sub-group was 59.0 year (sd=11.8), and the mean age of the "no clinical need" sub-group was 58.8 year (sd=12.3). mean ages in the two sub-groups remained comparable throughout the investigation period providing a power of 95.3% and 94.0% for the follow-ups, respectively (figure 2). figure 2: age groups at 6mfu divided into "clinical need" (n=26) and "no clinical need" (n=10). after 6mfu, we had collected 694 datasets, out of a maximum potential of 720 datasets, from the 36 subjects that completed the follow-up. this gave us a 3.6% rate of missing data (figure 1). missed appointments and software error accounted for the following instances of missing data: • at baseline/delivery: 2 class, 1 amppro, and 2 tug data sets • at 6wfu: 2 plus-m™, 2 class, 2 abcs, 4 tug and 3 amppro • at 6mfu: 2 eq-5d-5l®, 1 plus-m™, 1 class, 2 abc, 1 tug, and 2 amppro outcome measure results are presented in three sections below. the first section presents data including all participants that completed the 6mfu. the following sections present findings from the two sub-groups within the cohort – "clinical need" and "no clinical need" sub-groups. satisfaction and functional assessment of all participants (n=36) (table 2a): the eq-5d-5l® mean utility score was 0.75 using the existing prosthesis at baseline (sd=0.18). life quality increased significantly to 0.82 (sd=0.15) at 6wfu and to 0.84 (sd=0.12) at 6mfu. the plus-m™ score at baseline on the existing prosthesis was 46 (sd=24). mean mobility scores rose significantly to 54 (sd=21) at 6wfu and to 61(sd=16) at 6mfu (e.g., >1 standard deviation above the mean after 6mfu). the class mean overall score improved significantly from 74% at baseline with the existing interface to 86% on the day of fitting with ds-tf. this improvement was maintained during the follow-up period (figure 3). 0 1 2 3 4 5 6 7 8 9 10 (33,39) (39,45) (45,51) (51,57) (57,63) (63,69) (69,75) (75,81) n age in years age groups at 6 month follow up clinical need no clinical need https://doi.org/10.33137/cpoj.v4i1.36065 6 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 issn: 2561-987x transfemoral direct socket interface walker et al. 2021 cpoj the cohort's abc mean score at baseline was 63% (sd=25) on the existing prosthesis. the scores rose significantly to 75% at 6wfu and further to 78% at 6mfu. the tug mean time at baseline on the existing prosthesis was 14.7sec. (sd=7.4) compared to 14.0 sec. (sd=6.5) with ds-tf. tug times improved significantly to 13.0 sec. (sd=6.5) at 6wfu and 12.8 sec. (sd=6.5) at 6mfu. the cp noted whether subjects elected to use an assistive device or not when completing the amppro (and tug) (figure 4). the amppro mobility mean score at baseline was 38 (sd=6.0). scores increased to 40 (sd=5.4) at 6wfu and remained at 40 (sd=5.5) at 6mfu (table 2 and figure 4). several subjects exhibited improved k level and/or reduced use of assistive devices during the study period: • one k1 subject increased function up to k2 level using 1 cane • one k2 progressed from a walking frame to 1 cane. • one k2 who previously used a cane no longer required an assistive device • one k2 advanced to the k3 level while discontinuing the use of a cane • one k3 went from currently using a walker to using one cane • one k3 discontinued the use of two crutches to using no assistive device • one k2 went from using no aid to using one cane • 7 subjects (using no aid) increased from k3 to k4 • one subject using no aid declined from k4 to k3 at the 6mfu (figure 4) all outcome measures (incl. opus from the previous article) showed significant improvement (figure 5a) for the cohort. satisfaction and functional assessment of participants with the clinical need for new interface (n=26), (table 2b): eq-5d-5l®, plus-m™, abc, and amppro results in this sub-group are similar to the whole group, showing statistically significant (p=<.001) improvement during the investigation period (table 2 and figure 5b). the mean tug time at baseline on the existing prosthesis was 14.2sec. (sd=7.4). mean tug time on the day of fitting with the new interface was 13.2 sec. (sd=5.5) and the time improved further to 13.0 sec. (sd=5.7) at 6wfu and 12.7 sec. (sd=5.3) at 6mfu. both tug and amppro showed statistically significant improvement in function (p=0.02) (table 2b). satisfaction and functional assessment of participants without the clinical need for new interface (n = 10), (table 2c): the outcome of eq-5d-5l® and the plus-m™ did not reach statistical significance in this sub-group. however, the figure 3: class score at baseline (with existing socket) and at delivery of the new socket, including follow-up at 6 weeks and 6 months. baseline delivery 6wfu 6mfu baseline delivery 6wfu 6mfu class score class score https://doi.org/10.33137/cpoj.v4i1.36065 7 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 issn: 2561-987x transfemoral direct socket interface walker et al. 2021 cpoj outcomes directly related to the new interface function (class and amppro) showed significant improvement at 6mfu. additionally, the mean tug time in this sub-group at baseline on the existing prosthesis was 15.9sec. (sd=7.6); that is higher than the "clinical need" sub-group. mean tug time on the day of fitting with dstf was 16.1sec. (sd=5.5) and improved to 13.0sec. (sd=5.0) and 12.9sec. (sd=5.1) at 6wfu and 6mfu (p=0.04), respectively, (table 2c). 0 2 4 6 8 10 12 14 16 18 20 b 6mfu b 6mfu b 6mfu b 6mfu k levels1 k levels2 k levels3 k levels4 subjects k-levels at basline and at 6 month follow up by assistiv device none on cane two crutches walker figure 4: changes from baseline to 6mfu in k levels using the amppro score, and assistive device use. figure 5: a: illustrating changes (index value from 0-100%) in outcomes for all participants that completed the study from baseline (orange) to 6mfu (blue) for all measures except tug. b and c: illustrating changes (measured on a scale from 0-100%) in outcomes for the "clinical need" sub-group and the "no clinical need" sub-group (5c), from baseline (orange) to 6mfu (blue) for all measures except tug. abc plus-m™ class opus csdamppro eq-5d-5l opus css no clinical need six month cohort 6mfu baseline abc plus-m™ class opus csdamppro eq-5d-5l opus css full six month cohort 6mfu baseline abc plus-m™ class opus csdamppro eq-5d-5l opus css clinical need six month cohort 6mfu baseline a b c 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% https://doi.org/10.33137/cpoj.v4i1.36065 8 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 issn: 2561-987x transfemoral direct socket interface walker et al. 2021 cpoj table 2: outcome measurements from all subjects (a) of the cohort, with clinical need (b) and without clinical need (c). a (all subjects) baseline* (n=36) delivery** (n=36) 6wfu (n=36) p 6mfu (n=36) p eq-5d-5l® (index value) 0.75 (0.18) 0.82 (0.15) <.001 0.84 (0.12) <.001 missing 2 (5.4%) plus-m™(percentile) 46.0 (23.6) 54.3 (20.6) <.001 61.4 (16.0) <.001 missing 2 (5.4%) 1 (2.7%) class (percentage) 65.8 (23.1) 84.8 (11.6) 85.1 (13.2) <.001 87.6 (12.2) <.001 missing 1 (2.7%) 1 (2.7%) 2 (5.4%) 1 (2.7%) abc (percentage) 63 (25) 75 (15) <.001 78 (13) <.001 missing 2 (5.4%) 2 (5.4%) tug (sec.) 14.7 (7.4) 14.0 (6.5) 13.0 (5.4) <.001 12.8 (5.2) <.001 missing 2 (5.4%) 4 (10.8%) 1 (2.7%) amppro (score) 38.0 (6.0) 39.8 (5.4) <.001 39.6 (5.5) <.001 missing 1 (2.7%) 3 (8.1%) 2 (5.4%) b (with clinical need) baseline* (n=26) delivery** (n=26) 6wfu (n=26) p 6mfu (n=26) p eq-5d-5l® (index value) 0.71 (0.19) 0.81 (0.17) <.001 0.84 (0.14) <.001 missing 2 (7.4) plus-m™(percentile) 45.8 (22.2) 54.5 (21.3) <.001 61.2 (15.7) <.001 missing 2 (7.4) 1 (3.7) class (percentage) 62.0 (25.3) 85.4 (11.6) 86.0 (14.7) <.001 88.2 (12.6) <.001 missing 1 (3.7) 2 (7.4) 2 (7.4) abc (percentage) 61 (26) 75 (15) <.001 77 (12) <.001 missing 2 (7.4) 2 (7.4) tug (sec.) 14.2 (7.4) 13.2 (5.5) 13.0 (5.7) 0.08 12.7 (5.3) 0.02 missing 1 (3.7%) 3 (11.1%) 1 (3.7%) amppro (score) 37.8 (6.7) 39.6 (5.6) 0.01 39.0 (6.1) 0.02 missing 2 (7.4%) 2 (7.4%) c (without clinical need) baseline* (n=10) delivery** (n=10) 6wfu (n=10) p value 6mfu (n=10) p eq-5d-5l® (index value) 0.83 (0.11) 0.84 (0.09) 0.93 0.86 (0.08) 0.50 missing plus-m™(percentile) 46.5 (28.4) 53.8 (20.0) 0.50 62.0 (17.9) 0.06 missing class (percentage) 74.2 (14.9) 83.2 (12.3) 83.2 (9.5) 0.03 86.3 (11.6) <.001 missing 1 (10.0%) abc (percentage) 68 (22) 73 (17) 0.44 81 (15) 0.01 missing tug (sec.) 15.9 (7.6) 16.1 (8.8) 13.9 (4.7) 0.02 12.9 (5.1) 0.04 missing 1 (10.0%) 1 (10.0%) amppro (score) 38.8 (5.1) 40.3 (5.1) 0.08 41.1 (3.4) <.001 missing 1 (10.0%) 1 (10.0%) all data are presented as mean (sd). missing data were not included in the statistical tests. * baseline measurement regarding existing interface (as a part of the prosthesis). ** baseline measurement regarding the ds-tf interface (as a part of the prosthesis) https://doi.org/10.33137/cpoj.v4i1.36065 9 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 issn: 2561-987x transfemoral direct socket interface walker et al. 2021 cpoj discussion aggregate results revealed that the study subjects experienced multifaceted improvements during the study. in the "clinical need" sub-group, the eq-5d-5l® outcome measure showed significant improvement in the user's health state compared with the previous interface. the eq-5d-5l® mean utility score (0.75), using the existing prosthesis at baseline, increased significantly to 0.84 at 6mfu, indicating that average ds-tf prosthesis users in this study cohort improved their qol and reached a level similar to the us norm population of 0.85.37 the plus-m™ score at baseline using existing prosthesis was 46, slightly lower than the mean mobility score of 50 reported for the plus-m™ development sample.45 however, the mean mobility scores rose significantly during the study, to 61 at 6mfu (>1 standard deviation above the mean (=10)). the cohort's abc mean score was 63% using the existing prosthesis at baseline, which is in line with findings by miller -a mean abc score of 64% among a comparative prosthetic-user population.39 however, the score rose significantly above the comparative population to 78% at 6mfu. tug test times showed significant improvement over the study period, indicating the ds-tf interface did not increase subjects' risk of falling. opus css and csd, also discussed in the previous article,27 showed significant improvements. the class outcomes after 6-months showed improvement in all subscales indicating increased user satisfaction with interface stability, suspension, and appearance (figure 5 a&b). the amppro mean scores significantly increase from 38 at baseline to 40 at 6mfu. the cohort’s mobility improvements were manifested in klevel increases, reduced dependency on assistive devices and the combination thereof. notice the cohort’s distribution on the graphs in figure 4 shift in a positive direction toward increased mobility from baseline to 6mfu. that a socket replacement could have a significant impact on k-level was an unexpected but enlightening outcome. to our knowledge, few studies have investigated qol changes using qaly instruments in the prosthetics field. those that exist were designed to examine the benefits of a knee unit rather than an interface.54,55 eq5d-5l scores in our study reveal a significant increase (p<0.001) in qol in a relatively large study cohort (for the prosthetics field) attributed to the interface. qol improvements are the culmination of all the other improvements, including perceived health status, mobility, satisfaction, stability, suspension, comfort, appearance, confidence, balance, pain, and fall-risk. no other known studies have investigated the effects of the tf interface on qol. traditional fitting timelines involve multiple fabrication steps, patient visits, and adjustments.16 this study's certified prosthetists delivered all ds-tf interfaces in a single visit. this reduces the number of visits typically required to fabricate and deliver a tf socket since ds tf eliminated check sockets for all subjects. there are several reasons why shortening the fitting timeline is important; however, sacrificing quality to gain speed is unacceptable. there is a glaring absence of published studies on outcomes focusing on fabrication methods and/or different interface designs. one study, by kahle et al., included 15 subjects comparing 3 socket designs. results showed no significant difference regarding socket position, movement, or comfort. kahle et al. stated that skeletal motion within the socket is an important but unquantified factor in outcomes.56 no other study with more than 5 subjects was found to compare interfaces regarding design and function over 6 months or demonstrate significant outcome improvements for an interface type.3 however, wurdeman et al. enrolled multiple subjects (n=509), but they did not compare various interfaces. the authors concluded that mobility has a strong positive correlation with both qol and general satisfaction in lower limb loss patient care.22 the absence of comparative studies could be due to a lack of good testing methodology (i.e., lack of sensitivity) and/or a lack of standardized subject inclusion criteria complexity, e.g., patient needs, cause of amputation, surgical technique, skin and soft tissue status/condition, age groups and overall health status.3 this study found improvements across multiple outcome measures of both the "clinical need" and "no clinical need" sub-groups. it is noteworthy that users with no perceived need for a socket replacement still experienced significant improvements with ds-tf. as an explanation for this, we might speculate that patients are reluctant to reveal their true thoughts on their current device because they dread the traditionally long fitting procedure and view it as a hurdle that is only worth mounting in certain circumstances. this study shows that ds-tf can sometimes improve patient function and satisfaction regardless of the perceived "clinical need of a new socket". while this study presents a standardized process for fabrication and delivery of ds-tf, an important question remains: would our field (both practitioners and users) benefit from a more standardized criteria for determining whether or not a patient has a "clinical need" for a new interface? class, as a clinical instrument, could be a viable choice for standardizing socket assessment and replacement. class was developed in 2019 with the intention of being more descriptive than the socket comfort score.38,57 clinicians or investigators may use it to follow prosthesis users’ socket fit and function over time in clinical care or clinical studies, but further research is needed. although socket fit is often highlighted in studies as important, the descriptions differ and often lack defining terms.17 thus, there is no indication that "good fit" means the same things to everyone.14 there is also a void of https://doi.org/10.33137/cpoj.v4i1.36065 10 walker j, marable w.r, smith c, sigurjónsson b.þ, atlason i.f, johannesson g.a. clinical outcome of transfemoral direct socket interface (part 2). canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.6. https://doi.org/10.33137/cpoj.v4i1.36065 issn: 2561-987x transfemoral direct socket interface walker et al. 2021 cpoj investigations on other socket designs measuring the correlation in outcomes regarding mobility and qol. of the few studies that look at prosthesis user mobility, most focus on the tt level. if the study does include transfemoral prosthesis users, the focus is on the artificial knee,22 or the reference values are still being validated.58 also, as pointed out in the previous article,27 interface designs lack standardized descriptions.17 further limitations exist in the disparity of the study subjects. a documented assessment of condition and capabilities following a standardized approach could improve our ability to compare results across different studies. the present study possesses four central strengths: a comparatively large study cohort (n=47), representative of a relatively normal transfemoral prosthesis user population,2 with a comparatively long investigational period (6 months), and using 7 different validated outcome measures. selecting and combining both subjective and objective measures in this way over a 6-month period gives a broad and deep picture of ds-tf users' outcomes. we are aware of no other published study on tf interfaces of this size, duration, and scope of outcome measures. conclusion ds-tf users experienced improved qol, satisfaction, comfort, and function with their new interface, along with increased mobility compared to the previous interface. these findings also revealed that interface replacement with ds-tf could increase objectively measured user klevel, even when socket replacement isn't clearly clinically indicated. future studies should include randomized controlled comparisons between different prosthetic interface designs and their impact on prosthetic user qol and mobility. additional future studies should contain procedures for identifying a standardized approach to determine when an interface replacement is appropriate. acknowledgements we would like to acknowledge the cp´s who participated in the study: j. arnold, b. sampson, s. parkinson, c. smith, b. clark, c.z. smith and the technicians involved including c. keeling, r. camper and e. thompson. declaration of conflicting interests all authors are employees of össur hf except i. f. atlason. study principle investigators received no compensation from össur hf. author contribution • joel walker: conceptualization; study oversight; data collection; writing original; review and editing. • w. russ marable: conceptualization; study oversight; writing original; review and editing. • christian smith: conceptualization; data collection; review and editing. • benedikt þorri sigurjonsson: conceptualization; obtained funding; study oversight; data analysis; review and editing. • ingi freyr atlason: data analysis. • g. anton johannesson: conceptualization; study oversight; data analysis; writing original; review and editing. sources of support this study was financially supported by össur hf. ethical approval ethical approval was obtained from advarra® irb (cr00128417) and the investigation was registered at clinical trials.gov nct04312724. signed informed consent was obtained from all participants. references 1.mathis sl. factors associated with mobility apprehension in persons with lower limb amputation. prosthet orthot int. 2020;44(4):208–214. doi:10.1177/0309364620915017 2.kamrad i, söderberg b, örneholm h, hagberg k. swedeamp— the swedish amputation and prosthetics registry: 8-year data on 5762 patients with lower limb amputation show sex differences in amputation level and in 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the 2-minute walk test as a measure of mobility in people with lower limb amputation. arch phys med rehabil. 2020;101(7):1183–1189. doi:10.1016/j.apmr.2020.03.007 https://doi.org/10.33137/cpoj.v4i1.36065 https://www.ncbi.nlm.nih.gov/books/nbk531517/table/ch2.tab1 https://www.ncbi.nlm.nih.gov/books/nbk531517/table/ch2.tab1 https://www.opsoutcomes.com/ops-proapp-privacy-notice https://euroqol.org/eq-5d-instruments/ http://plus-m.org/ https://bacpar.csp.org.uk/system/files/toolbox_version_2.pdf https://www.psychologie.hhu.de/arbeitsgruppen/allgemeine-psychologie-und-arbeitspsychologie/gpower.html https://www.psychologie.hhu.de/arbeitsgruppen/allgemeine-psychologie-und-arbeitspsychologie/gpower.html https://github.com/lme4/lme4/ all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 6, issue 1 2023 research article miyata y, sasaki k, guerra g, dacharux w, chaiwan p. evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.5. https://doi.org/10.33137/cpoj.v6i1.41865 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v6i1.41865 1 miyata y, sasaki k, guerra g, dacharux w, chaiwan p. evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.5. https://doi.org/10.33137/cpoj.v6i1.41865 research article evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users miyata y1, sasaki k1*, guerra g2, dacharux w3, chaiwan p1 1 sirindhorn school of prosthetics and orthotics, faculty of medicine siriraj hospital, mahidol university, bangkok, thailand. 2 department of exercise and sport science, st. mary’s university, san antonio, tx, usa. 3 department of anatomy, faculty of medicine siriraj hospital, mahidol university, bangkok, thailand. introduction transtibial amputations are prevalent worldwide, particularly in low and middle-income countries, due to various factors such as diabetes, trauma, and congenital conditions. prosthetic treatment is vital for improving the satisfaction of people with amputation, and enhancing their quality of life (qol).1,2 however, people with amputation in resource limited environments (rle) face a range of challenges, encompassing issues of accessibility, constraints related to available resources, and the quality of prosthetic devices.3 rehabilitation success in people with lower limb amputation depends on factors like preamputation mobility, time between amputation and prosthetic fitting, and material selection.4 the elements taken into consideration for prosthetic intervention include the affordability, fabrication time, safety, and durability of the material. thus, the selection of appropriate materials for the development of prosthetic devices plays a crucial role in enhancing the qol for people with amputation.5 the effectiveness of interface materials, particularly their impact on the residual limb, is an intriguing area of study. roll-on gel liners, for instance, have shown higher satisfaction levels compared to polyethylene foam (pelite).6 the ethylene-vinyl acetate (eva) material exhibits similarities to pe-lite because both are closed-cell polymers. eva is widely used in a multitude of product applications and is acknowledged for its cost-effectiveness. open access abstract background: the choice of prosthetic socket interface material significantly affects user comfort and satisfaction. the affordable ethylene-vinyl acetate roll-on (aero) liner was created with the aim of improving functionality and streamlining the wearing process for users. objective: the purpose of this study was to comprehensively assess user satisfaction, comfort, and durability of the aero liner and compare it with the common soft pe-lite liner. methodology: fourteen individuals with transtibial amputation participated in this three-month randomized crossover trial study. the prosthesis evaluation questionnaire (peq), expanded socket comfort score (escs), and liner thickness measurements were used to comprehensively compare the aero and pe-lite liner. findings: the aero liner demonstrated notable improvements in prosthetic comfort and functionality over pe-lite liner. after three months use, there was a significant reduction in reported frustration with the aero liner (p=0.023, r=0.604) in the peq subscale. specific aspects, such as walking with the prosthesis (p=0.030, r=0.601) and odor perception (p=0.024, d=0.579), favored the use of the aero liner. the expanded socket comfort score (escs) revealed significant superiority for the aero liner “at best” (p=0.04) and “on average” (p=0.02) after one and three months, respectively. liner thickness analysis showed significant reductions at the mid-patellar tendon location for the aero liner at one (0.57±0.48) and three months (0.90±0.69, p=0.01) and in the posterior region after three months (0.63±0.64, p=0.05). conclusion: our study highlights the potential advantages of the aero liner in enhancing comfort and satisfaction. yet, durability and thinning of the liner when compared to pe-lite may be a concern which may eventually affect socket fit. these findings contribute to ongoing efforts to optimize prosthetic interventions and improve the quality of life of individuals with lower limb prosthesis in resource-limited environments. article info received: october 15, 2023 accepted: december 19, 2023 published: december 26, 2023 citation miyata y, sasaki k, guerra g, dacharux w, chaiwan p. evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.5. https://doi.org/10.33137/cpoj.v6i 1.41865 keywords limb loss, amputation, prosthesis, rehabilitation, prosthetic, prosthetic liner, satisfaction, comfort, quality of life, questionnaire, socket comfort * corresponding author: kazuhiko sasaki, sirindhorn school of prosthetics and orthotics, faculty of medicine siriraj hospital, mahidol university, bangkok, thailand. email: kazuhiko.sas@mahidol.edu orcid id: https://orcid.org/0000-0002-1778-6308 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 1, article no.5. 2023 https://doi.org/10.33137/cpoj.v6i1.41865 https://doi.org/10.33137/cpoj.v6i1.41865 https://doi.org/10.33137/cpoj.v6i1.41865 https://orcid.org/0000-0002-1778-6308 https://jps.library.utoronto.ca/index.php/cpoj/index 2 miyata y, sasaki k, guerra g, dacharux w, chaiwan p. evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.5. https://doi.org/10.33137/cpoj.v6i1.41865 canadian prosthetics & orthotics journal issn: 2561-987x evaluating feasibility and durability of the aero prosthetic liner miyata et al., 2023 a cost-effective alternative, referred to as the affordable ethylene-vinyl acetate roll-on (aero) liner, has been created with the aim of improving functionality and streamlining the process of wearing for users.7 this prosthetic liner makes use of materials obtained from local sources and features a production method that is simple and easy to follow. consequently, it provides an economically viable and environmentally friendly alternative for prosthetic liners in locations with limited resources. preliminary pilot data suggested possible improvements in prosthesis comfort, stability, and pressure distribution in individuals with transtibial amputations. nevertheless, it is imperative to recognize the constraints arising from a limited sample size and the selection of participants with optimal residual limb configurations.8 therefore, assessing the liner's long-term impact and considering the user experience are crucial factors in revealing the strengths and weaknesses of the aero liner.9 it was hypothesized that for individuals using the aero liner prosthesis, comfort across a three-month use period would be maintained. thus, our study purpose was to explore utility of the aero liner in prosthesis users during a three-month period. methodology participants this study was approved by the siriraj faculty of medicine institutional review board (si 419/2022). this study involved the participation of thirteen people with unilateral transtibial amputation and one with bilateral transtibial amputations. prior to their involvement, all participants provided informed consent. experimental protocol this study utilized a crossover design in which participants were randomly assigned to pe-lite or aero liner groups (figure 1). a certified prosthetist created and fit all the prostheses, which were patella tendon bearing (ptb) socket with pe-lite liner, in our clinic. and aero liners were fit with either a prefabricated or custom-made liner. in total there were fourteen participants. liners were either prefabricated in small, medium, and large sizes. or custom made for a unique limb shape. ten unilateral participants used prefabricated liners, three unilateral participants used custom liners, and finally one bilateral participant used a prefabricated liner on one limb and custom liner on the other limb. pe-lite liners were also fabricated specifically for all participants. both liners were fabricated from a 5 mm thick material. no adjustments were necessary for user of ptb sockets with cuff strap. however, minor adjustments, such as the addition of a pad were made for ptb sockets with supracondylar suspension designs to ensure suspension. the prosthetist also instructed the participants on how to perform the roll-on donning method to ensure consistent and unbiased donning. the aero liner was provided with two liners per each participant, one designated for primary use and the other as a spare liner. participants were instructed to change to using the spare liner only if necessary for limb comfort and function. this approach ensured that participants had access to a backup liner in case of wear and tear or other unforeseen circumstances during the study. the thai peq10 was used to evaluate patient satisfaction across different domains. the peq, originally developed in english, is composed of 82 questions, which are further divided into 9 subscales. these subscales are ambulation (am), appearance (ap), frustration (fr), perceived response (pr), residual limb health (rl), social burden (sb), sounds (so), utility (ut), and well being (wb). in this study, we used four subscales: am, fr, rl, and ut, which are related to interface material evaluation. additionally, we assessed nine individual items to gain insight into the effect of the liner on the patients. participants completed the peq after one month and three months of using their prosthetic device. the participant’s comfort was assessed using the expanded socket comfort score (escs). traditionally employed straightforward questionnaires may assess prosthetic comfort, however, obtaining feedback from users regarding their experiences with best, worst, and average comfort levels is one approach. this approach offers a more comprehensive evaluation of socket comfort than solely considering current comfort ratings.11 we assessed pressure-sensitive and pressure-tolerant areas, including the mid-patellar tendon (mpt), tibial tubercle, distal end of the tibia, head of the fibula, medial flare, and posterior region. the liner thickness was measured using a depth gauge caliper, which measured the liner material, as shown in figure 2. a caliper depth bar precision of 0.05 mm was utilized to evaluate liner thickness at intervals of 1 month and 3 months for each liner. these three outcome measures, peq, escs, and liner thickness evaluation, were administered for pe-lite and aero liner prostheses. data analysis statistical analysis was conducted using r statistical software version 4.2.0 (r project for statistical computing). to analyze the performance on the peq and escs between pe-lite and aero liner at one month and three months, a wilcoxon signed rank test (p < 0.05) was used. the designation “nr” for non-responses, which signified the absence of pain associated with the device, was evaluated using the mann-whitney u test. the peq effect size was calculated using r, with interpretation based on established criteria: d > 0.10 denoting a small effect, d > 0.30 indicating a medium effect, and d > 0.50 signifying a large effect, depending on the statistical significance of the findings. the liner thickness for both pe-lite and aero liner was analyzed using a student’s t-test for one and three-month. https://doi.org/10.33137/cpoj.v6i1.41865 3 miyata y, sasaki k, guerra g, dacharux w, chaiwan p. evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.5. https://doi.org/10.33137/cpoj.v6i1.41865 canadian prosthetics & orthotics journal issn: 2561-987x evaluating feasibility and durability of the aero prosthetic liner miyata et al., 2023 figure 1: flowchart of participant allocation during the study, n= number of participants. note: the number of participants: thirteen with unilateral transtibial amputations and one with bilateral transtibial amputation. assessed eligible participants (n= 4) nformed consent allocated to intervention a (n= ) allocated to intervention (n= ) analyzed intervention a (n= ) analyzed intervention (n= ) analyzed intervention , allocated to intervention a (n= ) analyzed intervention a, allocated to intervention (n= ) analyzed intervention a (n= ) analyzed intervention (n= ) analyzed intervention (n= ) analyzed intervention a (n= ) randomization month analysis months analysis, allocation crossover month analysis months analysis allocation concluded study figure 2: the six areas used for evaluating liner thickness: (a) mid patellar tendon, (b) tibial tubercle, (c) distal end of tibia, (d) head of fibula, (e) medial flare, and (f) posterior. liner thickness was check using the following procedure; (1) prepare caliper depth gauge and metal bar to sandwich the liner, (2) penetrate liner and check for contact with metal bar, (3) check the thickness of the caliper gauge. https://doi.org/10.33137/cpoj.v6i1.41865 4 miyata y, sasaki k, guerra g, dacharux w, chaiwan p. evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.5. https://doi.org/10.33137/cpoj.v6i1.41865 canadian prosthetics & orthotics journal issn: 2561-987x evaluating feasibility and durability of the aero prosthetic liner miyata et al., 2023 results this study involved fourteen participants, thirteen with unilateral transtibial amputations and one with bilateral transtibial amputation. the participants included twelve males with an average age of 52.1±10.4 years, and two females with an average age of 59.5±0.7 years. all participants used ptb prosthetic sockets, with eight using a cuff strap suspension system, including one person with bilateral transtibial amputation and six using an anatomical supracondylar suspension. analysis of the peq revealed a significant reduction in reported frustration after three months with the aero liner (p=0.023, r=0.604). additionally, specific items related to walking with the prosthesis (p=0.030, r=0.601) and odor perception (p=0.024, d=0.579) indicated better results with the aero liner compared to pe-lite after three months. while participants generally expressed a preference for the aero liner, most preferences did not reach statistical significance compared to pe-lite (figure 3). three participants in the pelite group indicated “nr” (no pain at the residual limb) at both one month and three-month assessments. in contrast, within the aero liner group, four participants reported “nr” after one month, and this number increased to five participants after three months (figure 3). the result of the escs for the aero liner, showed significantly superior results when compared to pe-lite “at best, over the last days”, 8.0± .6 (p=0.04) after one month and “on average, over the last days”, 8. ±0.9 (p=0.02) after three months (figure 4). a significant reduction in liner thickness was observed at the mpt location for the aero liner compared to pe-lite, both after one month 0.57±0.48 and three months 0.90±0.69 follow-up (p=0.01). additionally, a significant difference was noted in the posterior region after three months 0.63±0.64 (p=0.05) (figure 5). discussion we investigated the satisfaction, comfort, and changes in liner thickness of transtibial prosthetic users during threemonth use of aero and pe-lite liner. the findings of this study shed light on several crucial aspects of transtibial prosthetic use and, in particular, the impact of the aero liner on user experience. our results demonstrated a significant reduction in reported frustration after three months of utilizing the aero liner compared to pe-lite liner. participants expressed a preference for the aero liner, although this preference did not reach statistical significance when compared with pe-lite liner. these findings suggest that the aero liner offers notable improvement in terms of user experience, particularly with regard to frustration reduction. frustration reduction can play a crucial role in enhancing overall prosthetic satisfaction, as users are more likely to continue using devices that minimize daily challenges and discomfort.12,13 although the preference for the aero liner did not reach statistical significance, it is possible that with a larger sample size, this trend might become more pronounced. therefore, future research with a larger participant pool may provide further insights into the preference of the aero liner over the pe-lite liner. figure 3: prosthesis evaluation questionnaire per subscale and individual items at one and three months for pe-lite and aero liner. * indicates significant differences (p<0.05). pain is a significant concern for individuals using prosthetic devices as it can affect mobility, quality of life, and long-term compliance with prosthetic use.14-16 three participants reported “nr” (no pain in the residual limb) when using pelite after one and three months. in contrast, in the aero liner group, four participants reported “nr” after one month, and this number increased to five participants after three months. roll-on donning of the aero liner may permit accommodation to the residual limb surface, and liner softness may reduce pain. although differences were minimal, these findings suggest that the aero liner might have contributed to a slightly reduced pain perception in users. pe-lite better aero better ambulation frustration residual limb health utility ambulation frustration residual limb health utility fit of prosthesis donning/doffing walking with prosthesis feeling with prosthesis skin irritation smell wound pain sweat fit of prosthesis donning/doffing walking with prosthesis feeling with prosthesis skin irritation smell wound pain sweat sub scale: 1 month p-value r sub scale: 3 months individual items: 1 month p-value r individual items: 3 months https://doi.org/10.33137/cpoj.v6i1.41865 5 miyata y, sasaki k, guerra g, dacharux w, chaiwan p. evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.5. https://doi.org/10.33137/cpoj.v6i1.41865 canadian prosthetics & orthotics journal issn: 2561-987x evaluating feasibility and durability of the aero prosthetic liner miyata et al., 2023 figure 4: expanded socket comfort score results at one and three months for pe-lite and aero liner. * indicates significant differences (p<0.05). p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s figure 5: liner thickness differences over time between the one month and three-month intervals. these changes are analyzed across six regions: mpt; mid patellar tendon, fibula head, distal end of tibia, medial flare, tibial tuberosity and posterior. * indicates significant differences (p<0.05), and **(p<0.01). p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s p e -l it e 1 m o n th a e r o 1 m o n th p e -l it e 3 m o n th s a e r o 3 m o n th s l in e r th ic k n e s s r e d u c ti o n ( m m ) l in e r th ic k n e s s r e d u c ti o n ( m m ) https://doi.org/10.33137/cpoj.v6i1.41865 6 miyata y, sasaki k, guerra g, dacharux w, chaiwan p. evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.5. https://doi.org/10.33137/cpoj.v6i1.41865 canadian prosthetics & orthotics journal issn: 2561-987x evaluating feasibility and durability of the aero prosthetic liner miyata et al., 2023 prosthetists often express concern about liner durability when prescribing devices.5 liner thickness is a critical factor for prosthetic comfort and fit. in our analysis, we observed significant differences in the liner thickness changes over time, particularly at the mpt location. the aero liner demonstrated a greater reduction in liner thickness at both one month and three months compared to the pe-lite liner. additionally, a significant reduction in liner thickness was noted in the proximal posterior region after three months. the softer aero liner, which has more flexible material properties, may contribute to the observed reduction in liner thickness. also, the observed outcome is attributed to the proximal pressure exerted on the aero liner. prolonged exposure to such pressures could potentially compromise the liner's durability, leading to discomfort within the prosthesis. therefore, it is essential to consider the shape of the prosthetic socket to avoid localized pressure. one approach to minimize the impact of these symptoms is socket design. in this study, all participants used the ptb socket, which is a common choice for rle. the ptb socket was designed to provide proximal compression within the socket for weight bearing. however, concerns have been raised in some studies about the potential impact of this socket design on residual limb.17,18 given the roll-on application method of the aero liner, it may be worth exploring the suitability of total surface bearing socket (tsb) to enhanced comfort and load distribution.19-21 evenly distributing pressure across the liner is believed to reduce localized pressure points and maintain consistent liner thickness.22,23 limitations the limitations of this study must be acknowledged. the relatively small sample size may have influenced the statistical significance of certain findings such as user preferences. since participants had the option to change to their aero spare liner if necessary, this may have had an effect on satisfaction and odor. future research, with larger and more diverse participant pools, may provide additional insights. outcomes of interest in this study was comfort and satisfaction, which are pivotal factors that influence the acceptance and long-term use of prosthetic devices. previous studies have recognized the effectiveness of gel liners but have also highlighted concerns related to discomfort resulting from sweating.6 while the aero liner facilitates roll-on donning for a better fit with the residual limb, our investigation did not reveal any significant evidence supporting the notion that aero liner usage is linked to increased perspiration. conclusion in conclusion, this study highlights a potential comfort and satisfaction benefit of using the aero liner. however, proximal liner thickness may reduce over time which might impact socket fit and comfort. while our results indicate promising trends, further research is needed to confirm these findings and explore the interplay between liner types, socket shapes, and user experiences comprehensively. these findings contribute to ongoing efforts to enhance the quality of life of individuals with lower limb amputations who reside in rle by optimizing prosthetic interventions. acknowledgements the authors would like to express their gratitude to the participants of this research and acknowledge the support from the faculty of medicine, siriraj hospital, mahidol university. declaration of conflicting interests the authors declare no conflicts of commercial or financial interest in this research. authors contribution • yusuke miyata: original drafting, writing, data collection, statistical analysis. • kazuhiko sasaki: conceptualization, writing, data collection, statistical analysis. • gary guerra: writing, statistical analysis, proofing. • woratee dacharux: writing, data collection, proofing. • pilipda chaiwan: writing, data collection, proofing. sources of support this research received funding from the faculty of medicine, siriraj hospital, mahidol university. ethical approval this study was approved by the siriraj faculty of medicine institutional review board (si 419/2022). references 1.atlas of amputations and limb deficiencies: surgical, prosthetic, and rehabilitation principles. 4th ed. rosemont: american academy of orthopaedic surgeons; 2016. 2.mcdonald cl, westcott-mccoy s, weaver mr, haagsma j, kartin d. global prevalence of traumatic non-fatal limb amputation. prosthet orthot int. 2021;45(2):105–114. doi: 10.1177/0309364620972258 3.standards for prosthetics and orthotics [internet]. world health organization, 2017; [cited 2023 november 23]. available from: https://apps.who.int/iris/handle/10665/259209 4.budinski s. predictive factors for successful prosthetic rehabilitation after vascular transtibial amputation. acta clin croat. 2021. doi:10.20471/acc.2021.60.04.13 5.hafner bj, cagle jc, allyn kj, sanders je. elastomeric liners for people with transtibial amputation: survey of prosthetists’ clinical practices. prosthet orthot int. 2017;41(2):149–56. doi:10.1177/ 0309364616661256 https://doi.org/10.33137/cpoj.v6i1.41865 https://apps.who.int/iris/handle/10665/259209 7 miyata y, sasaki k, guerra g, dacharux w, chaiwan p. evaluating feasibility and durability of the aero prosthetic liner in transtibial prosthetic users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.5. https://doi.org/10.33137/cpoj.v6i1.41865 canadian prosthetics & orthotics journal issn: 2561-987x evaluating feasibility and durability of the aero prosthetic liner miyata et al., 2023 6.ali s, abu osman na, arifin n, gholizadeh h, abd razak na, wan abas wab. comparative study between dermo, pelite, and seal-in x5 liners: effect on patient’s satisfaction and perceived problems. scientificworldjournal. 2014;2014:1–8, doi:10.1155/2014/769810 7.sasaki k, guerra g, rattanakoch j, miyata y, suntharalingam s. sustainable development: a below-knee prostheses liner for resource limited environments. j med devices. 2020;14(1):014501, doi:10.1115/1.4045835 8.miyata y, sasaki k, guerra g, rattanakoch j. sustainable, affordable and functional: reimagining prosthetic liners in resource limited environments. disabil rehabil. 2022;44(12):2941–7, doi:10.1080/09638288.2020.1844316 9.richardson a, dillon mp. user experience of transtibial prosthetic liners: a systematic review. prosthet orthot int. 2017; 41(1): 6-18. doi: 10.1177/0309364616631343 10.anyapho w, dajpratham p, muangpaisan w, pattaravoratham s, amattayakul m. reliability and validity of the thai version of the prosthesis evaluation questionnaire. the 16th national and international sripatum university online conference (spucon2021). https://spucon.spu.ac.th/filemanager/files/international%20papers. pdf 11.morgan sj, askew rl, hafner bj. measurements of best, worst, and average socket comfort are more reliable than current socket comfort in established lower limb prosthesis users. arch phys med rehabil. 2022;103(6):1201–4, doi:10.1016/j.apmr.2021.10.008 12.brunelli s, bonanni c, foti c, traballesi m. a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a trans-tibial amputation. can prosthet orthot j. 2020;3(1). doi:10.33137/cpoj.v3i1.33640 13.baars ec, schrier e, dijkstra pu, geertzen jhb. prosthesis satisfaction in lower limb amputees: a systematic review of associated factors and questionnaires. medicine. 2018; 97(39):e12296. doi: 10.1097/md.0000000000012296 14.webster jb, hakimi kn, williams rm, turner ap, norvell dc, czerniecki jm. prosthetic fitting, use, and satisfaction following lower-limb amputation: a prospective study. j rehabil res dev. 2012;49(10):1493, doi: 10.1682/jrrd.2012.01.0001 15.coleman kl, boone da, laing ls, mathews de, smith dg. quantification of prosthetic outcomes: elastomeric gel liner with locking pin suspension versus polyethylene foam liner with neoprene sleeve suspension. j rehabil res dev. 2004;41(4):591. doi: 10.1682/jrrd.2004.04.0591 16.bekrater-bodmann r. factors associated with prosthesis embodiment and its importance for prosthetic satisfaction in lower limb amputees. front neurorobot. 2021;14:604376. doi: 10.3389/fnbot.2020.604376 17.abu osman na, spence wd, solomonidis se, paul jp, weir am. the patellar tendon bar! is it a necessary feature? med eng phys. 2010;32(7):760–5, doi:10.1016/j.medengphy.2010.04.020 18.ho ky, harty m, kellogg j, teter k, lee sp, chang yj, et al. patellar tendon morphology in trans-tibial amputees utilizing a prosthesis with a patellar-tendon-bearing feature. sci rep. 2019;9(1):16392, doi:10.1038/s41598-019-52747-9 9.yiğiter k, şener g, ayar k. comparison of the effects of patellar tendon bearing and total surface bearing sockets on prosthetic fitting and rehabilitation. prosthet orthot int. 2002;26(3):206–12, doi: 10.1080/03093640208726649 20.safari mr, meier mr. systematic review of effects of current transtibial prosthetic socket designs—part 1: qualitative outcomes. j rehabil res dev. 2015;52(5):491–508, doi: 10.1682/jrrd. 2014.08.0183 21.safari mr, meier mr. systematic review of effects of current transtibial prosthetic socket designs—part 2: quantitative outcomes. j rehabil res dev. 2015;52(5):509–26, doi: 10.1682/jrrd.2014.08.0184 22.rajtukova v, hudak r, zivcak j, halfarova p, kudrikova r. pressure distribution in transtibial prostheses socket and the stump interface. procedia engineering. 2014; 96:374–81, doi: 10.1016/j.proeng.2014.12.106 23.ali s, abu osman na, eshraghi a, gholizadeh h, abd razak na bin, wan abas wabb. interface pressure in transtibial socket during ascent and descent on stairs and its effect on patient satisfaction. clin biomech. 2013;28(9–10):994–9, doi:10.1016/ j.clinbiomech.2013.09.004 https://doi.org/10.33137/cpoj.v6i1.41865 https://spucon.spu.ac.th/filemanager/files/international%20papers.pdf https://spucon.spu.ac.th/filemanager/files/international%20papers.pdf all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 6, issue 1 2023 research article lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1.42093 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v6i1.42093 1 lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1.42093 research article the ideal physical therapist from the perspective of individuals with limb loss lee d.j1*, gambale a1, nisani m1, miller c2, leung e2, rodgers m2, chilianis d2, marra m2 1 department of physical therapy, stony brook university, stony brook, ny, usa. 2 department of physical therapy, philadelphia college of osteopathic medicine, ga, usa. introduction with approximately two million individuals living with limb loss in the united states, it is paramount that individuals with limb loss receive appropriate treatment following this life altering event.1,2 limb loss can impact an individual's quality of life and function by limiting participation in valued activities. however, a comprehensive individualized rehabilitation program can help build a functional foundation for a safe transition back to society and daily life for individuals with limb loss. the rehabilitation team is multidisciplinary in nature and includes prosthetists and physical therapists (pt) as two key members. while the prosthetist has domain over the design, delivery, and function of the prosthetic device, the pt’s are responsible for promoting optimal physical function after the loss of a limb.3 research has shown the importance of the collaborative decision-making process between prosthetists and individuals with limb loss and the positive impact it has on patient-centered outcomes.4 this synergistic process was echoed for pt’s, with collaborative goal setting and problem-solving being of importance to the rehabilitation process.5 while qualitative studies have explored what those with limb loss value in the rehabilitation process and in their relationship with the prosthetist, there is little evidence on what traits make an ideal pt. a pt’s capacity to understand the qualities in which persons with limb loss value during rehabilitation may open the door for more efficacious treatment and improved outcomes. to our knowledge, there is a void in published research examining the traits and skill set of a pt that individuals with limb loss deem valuable. therefore, the purpose of this study is to understand the open access abstract background: effective rehabilitation after limb loss is necessary to maximize function and promote independence. physical therapists (pt) are one of the primary drivers of the rehabilitation process. while general physical therapy knowledge and abilities have been shown to be important to the rehabilitation process, it is unclear what individuals with limb loss value in their pt’s. objective: the purpose of this study was to understand the elements that define an ideal pt from the perspective of individuals with limb loss. methodology: mixed-method design consisting of a 20-item web-based survey and semistructured interviews that were administered to individuals 18 years or older, who spoke english, and had a history of lower limb loss. findings: individuals with limb loss describe an ideal pt as promoting a therapeutic alliance, having specialized knowledge, and collaborating with a prosthetist. knowledge of the pt as it relates to limb loss was found to be both the greatest facilitator and barrier to the rehabilitation process. conclusion: from the perspective of those with limb loss, an ideal pt promotes a strong therapeutic alliance through communication, has specialized knowledge when it comes to the limb loss rehabilitation process, and collaborates with the prosthetist to problem-solve throughout the rehabilitation process. article info received: november 14, 2023 accepted: december 10, 2023 published: december 22, 2023 citation lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1. 42093 keywords physical therapy, therapeutic alliance, limb loss, amputation, prosthesis, rehabilitation * corresponding author: daniel j. lee, phd, department of physical therapy, stony brook university, stony brook, ny, usa. email: daniel.lee.8@stonybrook.edu orcid id: https://orcid.org/0000-0003-1805-2936 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 1, article no.4. 2023 https://doi.org/10.33137/cpoj.v6i1.42093 https://doi.org/10.33137/cpoj.v6i1.42093 https://doi.org/10.33137/cpoj.v6i1.42093 file:///d:/cpoj/published%20articles/volume%206-2023/issue%201/article%20no.4/daniel.lee.8@stonybrook.edu https://orcid.org/0000-0003-1805-2936 https://jps.library.utoronto.ca/index.php/cpoj/index 2 lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1.42093 canadian prosthetics & orthotics journal issn: 2561-987x the ideal physical therapist for limb loss lee et al., 2023 elements that define an ideal pt from the perspective of persons with limb loss. methodology study design: this study utilized a mixed methods design following the coreq checklist for qualitative data collection. setting: amputee coalition national conference and video conferencing. participants: inclusion criteria were individuals who attended the amputee coalition national conference (august 2020), were 18 years of age or older, spoke english, had a history of lower limb loss with or without prosthesis use, and performed physical therapy after loss of limb. exclusion criteria included individuals that demonstrated cognitive impairments consistent with an inability to complete the survey and/or interview. ethics: institutional review board (irb) approval was obtained prior to the collection of data. all participants completed the informed consent process prior to starting the study. instruments: the quantitative portion of the study utilized a 20-item web-based survey hosted by qualtricsxm (provo, ut) designed specifically for use in this study. the survey can be found in appendix a. the qualitative portion of the study was performed using a semi-structured interview that explored participants feelings and beliefs about physical therapy care. the interview questions can be found in appendix b. prior to data collection, the survey and interview were piloted for ease of use, logic functionality, and efficiency, then revised based on feedback. researchers were trained in interview skills and procedures by an expert in mixed-methodology, completing two pilot interviews prior to data collection. participants provided written and/or verbal consent prior to participating in the survey and semi-structured interviews. procedures: all data were collected remotely using webbased surveys and video conference interviews secondary to social distancing mandates present at the time of the data collection (august 2020). participants who attended the amputee coalition national conference had the ability to visit the researcher’s virtual booth to learn about the survey and interview. an anonymous link was provided to the survey on a display page linked to the virtual booth. if a participant additionally wanted to participate in an interview following the survey, they were eligible for a $10 digital gift card. interviews were conducted via video conferencing software. there were no relationships established between the participants and researchers prior to the study commencement. each interview was audio recorded and transcribed prior to data analysis. data analysis: quantitative data were analyzed for trends using spss v25 (ibm corp. aramonk, ny). identified trends were presented in terms of means and likert scales ranked by participants. qualitative data were analyzed using an inductive approach with a constant comparison method to identify themes. the process was multi-stage, involving a pair of researchers first independently analyzing the transcripts from the interview to generate codes. then each member of the pair would compare their codes and work towards consensus. each pair analyzed four to five unique transcripts. once all the transcripts were coded, all research team members compared the generated codes and revised for consistency using the consensus method. once the codes were agreed upon, themes were then generated using the same iterative process described for the codes. disagreement was adjudicated by a separate researcher not involved in the original coding. sample size calculations were not performed for the survey portion given its descriptive nature and lack of statistical comparisons requiring adequate power to yield significance. however, an incentive of a $10 gift card was provided to encourage participation in the study as the greater number of data points allows for a more comprehensive understanding of the results. the qualitative sample size is based on the principle of data saturation which supports a smaller sample (typically 10-15 participants) for homogenous groups (e.g. individuals with lower limb loss who have experienced physical therapy attending a national conference). results quantitative characteristics of study population of the 92 completed surveys, 22 were excluded due to failure to provide complete demographic information, leaving 73 completed surveys. incomplete surveys were excluded to reduce potential bias and provide a more accurate representation of the study population. the participants were primarily female (53.0%) with a mean age of 54.4 years. most participants were educated beyond high school (88.0%), had an average of 13.6 years since their initial amputation, with most having had a transtibial level amputation (51%) due to trauma or infection (54.0%). predominant comorbidities of hypertension (29.7%) and hypercholesterolemia (14.9%) were most common. a summary of the demographic characteristics is presented in table 1. barriers to physical therapy responses from participants reported the pt's lack of knowledge about limb loss (58%) and pt’s lack experience treating persons with limb loss (47%) as having a very high impact as a barrier to physical therapy. additionally, the personality of the pt (38%) was reported to have a high https://doi.org/10.33137/cpoj.v6i1.42093 3 lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1.42093 canadian prosthetics & orthotics journal issn: 2561-987x the ideal physical therapist for limb loss lee et al., 2023 impact as a barrier to physical therapy. meanwhile, the cost of the physical therapy sessions (12%) and distance to the clinic (7%) were most frequently regarded as having no impact as a barrier to treatment. responses are shown in figure 1. table 1: survey demographics. demographics of study population (n =73) gender: % • female • male 53 47 age: (mean ± sd) 54.4 ± 16.2 highest level of education: % • general educational development test • high school • college • post-graduate 1 11 58 30 years since 1st amputation: (mean ± sd) 13.6 ± 14.9 reason for 1st amputation: % • trauma • infection • congenital • tumor • vascular disease • other 31.1 23.0 10.8 14.9 13.5 6.8 current amputation level: % • transtibial • transfemoral • hip disarticulation • foot 51 44 4 1 medical history: % • diabetes • high blood pressure • high cholesterol • arthritis • heart disease • covid-19 • other 14.9 29.7 17.8 9.9 10.9 2.0 14.9 facilitators to physical therapy participants reported a pt’s knowledge about limb loss rehabilitation (86%), one-on-one time spent with pt (57%), and the personality of the pt (51%) serving as very important facilitators of physical therapy. available equipment was most frequently (48%) regarded as an important facilitator of physical therapy. participants regarded involvement with amputee coalition (15%), number of patients with limb loss the pt treats a month (11%), and cost of physical therapy session (8%) as having no importance as a facilitator of physical therapy. responses are shown in figure 2. knowledge of the pt responses from participants reported knowledge of gait training with prosthesis (74%), knowledge of prosthesis fit (63%), and knowledge of when to contact a prosthetist (62%) as being very important. knowledge of current research regarding limb loss (35%) was most frequently regarded as being important. meanwhile, knowledge of prosthetic components (10%) and knowledge of problemsolving issues with fit of prosthesis (9%) were most frequently reported as having slight or no importance. physical therapy experience participants (79%) regarded having a very positive or positive experience with physical therapy, with 53% of participants reporting having a very positive experience. responses are shown in figure 3. figure 1: barriers to physical therapy. 0% 10% 20% 30% 40% 50% 60% 70% distance to clinic personality of physical therapist lack of equipment pt's lack of knowledge about limb loss rehab pt's lack of treating individuals with limb loss pt's lack of knowledge of new prosthetic technology pt's lack of relationship with prosthetist cost of pt sessions other: barriers to physical therapy very high impact high impact moderate impact slight impact no impact https://doi.org/10.33137/cpoj.v6i1.42093 4 lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1.42093 canadian prosthetics & orthotics journal issn: 2561-987x the ideal physical therapist for limb loss lee et al., 2023 d qualitative of the 73 completed surveys, 13 participants agreed to participate in conducted interviews. a summary of the demographic characteristics is presented in table 2. three themes were identified from the interviews: theme 1: communication is key participants reported valuing the therapeutic alliance that forms between the individual with limb loss and the pt. communication, an element of the therapeutic alliance, was cited as either a facilitator or barrier, as expressed in the participant quotes below: “the ones i hold in the highest esteem are the ones that... one, listened to me and recognized things that i needed to do day in and day out in terms of whatever my job was.” “it’s got to be a relationship built with communication, where the therapist has to listen to what the patient is and isn’t saying in response to things they are asked to do.” “when the pt listens to what i'm asking and understands or listens and reacts to what i need; not necessarily what a traditional rehabilitation program is. because i think it needs to be really individualized.” “i got so frustrated with the pt because i didn't need it… i wanted her to help me walk but she had me… every time i came, take off my prosthetic and do exercises. this is not why i'm here. i want to get on a treadmill. i want you to tell me how to walk because i'm walking with a limp.” figure 2: facilitators to physical therapy. 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% location of therapy clinic personality of therapist one-on-one time spent with you equipment available to use physical therapist’s knowledge about limb loss rehab physical therapist's knowledge of new prosthetic technology physical therapist’s relationship with prosthetist involvement with amputee coalition credentials of the pt number of persons with limb loss the pt treats a month length of pt session cost of pt sessions other: facilitators of physical therapy very important important moderately important slightly important not important https://doi.org/10.33137/cpoj.v6i1.42093 5 lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1.42093 canadian prosthetics & orthotics journal issn: 2561-987x the ideal physical therapist for limb loss lee et al., 2023 from these quotes it is evident that positive communication was supportive of a healthy therapeutic relation, while lack of clear communication, as demonstrated in the last quote, can lead to frustration, which in turn can weaken the therapeutic alliance. table 2: interview demographics. demographics (n=13) gender: % female male 77 23 age: (mean ± sd) 54.5 ± 14.7 highest level of education: % ged high school college post-graduate 0 7.7 61.5 30.8 years since 1st amputation: (mean ± sd) 9.9 ± 9.5 reason for 1st amputation: % trauma infection congenital tumor vascular disease other 30.8 23.1 0 15.4 7.7 23.1 current amputation level: % below knee above knee hip disarticulation foot 54 46 0 0 medical history: % diabetes high blood pressure high cholesterol arthritis heart disease covid-19 other 18.8 18.8 18.8 6.3 12.5 0 25 theme 2: specialized care for a specialized population participants reported that specialized knowledge was one of the most significant components of high-quality therapy for individuals with lower limb loss. participants in the study emphasized: “i think it’s important for amputees to work with someone who has an expertise in amputees and prosthetics, because it is such a specific niche in the field.” “it’s important that the pt has knowledge of the different prosthetics and the features, because if they don’t know it, i probably don’t either!” “first of all, a pt who is trained in the nuances of working with an amputee, that’s a must. because not only do we not ambulate the same, but we don’t have the ability to do many of the normal limb functions.” “the reason he [the pt] knew my leg was too short was he had different samples of different thickness socks. what he would have me do is have me stand on different ones, different thicknesses, until he determined this is the correct height. they didn’t do that in the large rehab hospital. that’s that extra attention to detail, his experience and knowledge gave him.” the theme outlines how individuals with limb loss value a pt with specialized knowledge and equipment. a pt with more knowledge and an in-depth understanding of limb loss rehabilitation is considered a more desirable provider for persons with limb loss. figure 3: physical therapy experience following limb loss. theme 3: the dynamic duo: pt’s and prosthetists participants in this study reported an increase in quality of care when the prosthetist was an active collaborator in their physical therapy plan of care. for instance, several participants found it beneficial to have the prosthetist present at their treatment sessions due to their expertise in handling prosthetic limbs and deeper comprehension of the mechanical nature of these medical supportive devices. perceptions of an effective therapeutic team were reiterated by participants: “my prosthetist was at my physical therapy appointments. she could adjust it while i was actually with a pt, and she could see what was happening while i was doing it. that made it a very positive experience.” “they [the pt’s] also bring in the certified prosthetist. that prosthetist is going to know more about that particular prosthetic that individual is wearing than the pt themselves.” “i found that the prosthetists were really the ones that know the devices much better, in order to gait train properly you really have to understand the mechanics of the device.” to provide the most comprehensive care for a patient with limb loss, it is crucial for the pt to recognize the strength in the specialized knowledge possessed by a prosthetist and the integral role they can play in facilitating increased quality patient care. when asked to describe what makes a pt ideal for working with persons with limb loss, participants described: “being open to the prosthetist, being open to the knowledgeable amputees that are out there and learning from them and then being able to share your expertise.” 0% 10% 20% 30% 40% 50% 60% very negative experience negative experience neutral positive experience very positive experience physical therapy experience following limb loss https://doi.org/10.33137/cpoj.v6i1.42093 6 lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1.42093 canadian prosthetics & orthotics journal issn: 2561-987x the ideal physical therapist for limb loss lee et al., 2023 in summary, incorporating the prosthetist benefits both the patient and the therapist, and therefore should be part of the treatment sessions and goal setting. discussion the purpose of this study was to explore the elements that define an ideal pt from the perspective of individuals with limb loss. the results of this study demonstrated that individuals with limb loss value the pts knowledge regarding limb loss rehabilitation, the collaboration between the prosthetist and the pt, and a strong therapeutic alliance. the therapeutic alliance the therapeutic alliance defines a shared trust and collaboration between the patient and the healthcare practitioner,6 and can be promoted through collaboration, communication, and personalized care for individuals with limb loss.4,7 the core of the therapeutic alliance is a patientcentered approach, a finding that is evident from the qualitative portion of this study. for example, patients who are engaged in decision-making for cosmetic design of the prosthesis felt empowered and had greater satisfaction with their prosthesis.7 while placing value and emphasis on building interpersonal relationships that foster healing has been found to be as important to outcomes as chosen interventions in physical therapy.8 additionally, health professionals that express their understanding and empathy with the focus on the patient, increase patient trust and contribute to positive experiences with physical therapy and prosthetic management.4,9 these findings are consistent with our study where participants related the importance of collaboration as a means to support healthy therapeutic relationships. participants in this study noted that communication can also be a barrier or facilitator to the rehabilitation process depending on the quality of the interaction. those participants who had a positive experience described the communication to be purposeful and focused on their specific needs as an individual with limb loss. however, at least one participant noted that, despite best intentions by the pt, the attempts at communicating were contributing to a negative experience because of the lack of collaborative goal-setting. active engagement and tailored communication related to decision-making and goal setting has been reported to enhance patient satisfaction with musculoskeletal physical therapy across settings and in private practice.6,10,11 findings from this study, corroborates results in the field of limb loss rehab and with other populations seen in physical therapy settings, further illustrating that strong therapeutic alliance built on positive communication leads to better outcomes.8,10-12 specialization of interest in this study, there was a disconnect between some of the participants quantitative versus qualitative values on the pt's knowledge of prosthetic devices. however, shih et al.12 found that individuals who received physical therapy expressed more positive comments related to perceived positive outcomes and benefits of therapy rather than on the prosthetic design. given that technological changes are abundant in the field of prosthetics, it would seem valuable for the pt to have high levels of knowledge about the prosthetic devices and their components. while this specialized knowledge of devices was promoted in some of the qualitative results, we saw less importance placed on this knowledge area than gait training or being able to manage the fit of the prosthesis. in the united states, less than 50% of the pt programs have stand-alone courses that spend a considerable amount of time promoting prosthetic-related content in their programs specific to the devices and components themselves.13 additionally, there is tremendous variability in the content emphasized and educational hours dedicated to training physical therapist ostensibly for reasons related to patient-centered outcomes. this may be interpreted as individuals with limb loss valuing the functional mobility and problem-solving aspects of patient care more than explicit knowledge on the prosthetic components. while components and devices were not regarded as being highly important, generally, a therapist's knowledge levels were shown to be either a facilitator or barrier to the rehabilitation process. while the mixed findings from this study do not clearly suggest knowledge of devices alone is of significant importance to the person with limb loss, it does emphasize the importance of being knowledgeable generally about the process in order to facilitate positive outcomes and reduce unwanted secondary complications.14 collaboration with the prosthetist building off the ideas of therapeutic alliances and the need for specialization, participants in this study valued the collaboration between the prosthetist and pt. coordinated care with improved pathways for access to amputation management, including pt, prosthetists, and peer-visitors was identified as essential for timely recover in individuals with limb loss.15 since the prosthesis is a medical device, alterations to its alignment and function are typically outside of the scope of a pt. this can create a frustrating experience during the rehabilitation process when modifications are needed but the prosthetist is not present. therefore, expressed frustration as reported in our study may be mitigated by having coordinated sessions where the pt and prosthetist work together to problem-solve gait and functional issues, with the prosthetist performing real-time modifications during the treatment. the ideal outcome is https://doi.org/10.33137/cpoj.v6i1.42093 7 lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1.42093 canadian prosthetics & orthotics journal issn: 2561-987x the ideal physical therapist for limb loss lee et al., 2023 that expedient solutions to mobility issues are provided without delaying the progression of the rehabilitation process. limitations as is the nature of qualitative research, the biases and beliefs of the researchers themselves may influence the interpretation of the data. while the research team employed techniques like triangulation, internal auditing, and independent adjudication to minimize the influence of bias, the fact that all members of the team were pt’s is worth noting. while we do not believe the data and results were influenced by this, we as researchers acknowledge that our view of physical therapy is positive and found the results to be confirmatory of these beliefs. another limitation is the generalizability of these results outside of the participant pool present at the amputee coalition national conference. while demographically they are representative of individuals with limb loss, the small sample size limits the generalizability of the results, requiring larger scale studies for future research. conclusion from the perspective of those with limb loss, an ideal pt promotes a strong therapeutic alliance through communication, has specialized knowledge when it comes to the limb loss rehabilitation process, and collaborates with the prosthetist to problem-solve throughout the rehabilitation process. acknowledgements we would like to thank the amputee coalition and all the participants in the study for their assistance. declaration of conflicting interests none. authors contribution • daniel j. lee: contributed to and oversaw all aspects of the study. • albert gambale: contributed to data collection, analysis, and writing of the manuscript. • maya nisani: contributed to data collection, analysis, and writing of the manuscript. • carol miller: contributed to review and interpretation of results and writing of the manuscript. • elizabeth leung: contributed to data collection and analysis. • madeline rodgers: contributed to data collection and analysis. • daniel chilianis: contributed to data collection and analysis. • matthew marra: contributed to data collection and analysis. sources of support no sources of support to report. ethical approval institutional review board (irb) approval was obtained prior to the collection of data. all participants completed the informed consent process prior to starting the study. references 1.lee dj, repole t, taussig e, edwards s, misegadesj, guerra j, et al. self-management in persons with limb loss: a systematic review. can prosthet orthot j. 2021;4(1). doi: 10.33137/ cpoj.v4i1.35098 2.ziegler-graham k, mackenzie ej, ephraim pl, travison t.g, brookmeyer r. estimating the prevalence of limb loss in the united states: 2005 to 2050. arch phys med rehabil. 2008;89(3):422-429. doi:10.1016/j.apmr.2007.11.005 3.grover p, karuppan cm. the lower limb-loss rehabilitation continuum (llrc)–a framework for program design and implementation. disabil rehabil. 2023;4:1-0. doi: 10.1080/09638288.2023.2207221 4.anderson cb, kittelson aj, wurdeman sr, miller mj, stoneback jw, christiansen cl, et al. understanding decision-making in prosthetic rehabilitation by prosthetists and people with lower limb amputation: a qualitative study. disabil rehabil. 2023;45(4):723-32. doi: 10.1080/09638288.2022.2037745 5.lee dj, litwin b, fernandez-fernandez a, gailey r. the experience of self-managing from the perspective of persons with lower limb loss, prosthetists, and pt’s. disabil rehabil. 2023;45(20):3284-92. doi: 10.1080/09638288.2022.2122599 6.pinto rz, ferreira ml, oliveira vc, franco m.r, adams r, maher c.g, et al. patient-centered communication is associated with positive therapeutic alliance: a systematic review. j physiother. 2012;58(2):77-87. doi:10.1016/s1836-9553(12)70087-5. 7.lee sp, mitchell c, repayo k, tillitt m, weber c, chien lc, et al. patient engagement in cosmetic designing of prostheses: current practice and potential outcome benefits. prosthet orthot int. 2022;46(4):e335-e340. doi: 10.1097/pxr.0000000000000113 8.brun-cottan n, mcmillian d.h. j. defending the art of physical therapy: expanding inquiry and crafting culture in support of therapeutic alliance. physiother theory pract. 2018;36(6):669– 678. doi: 10.1080/09593985.2018.1492656 9.schober t-l, abrahamsen c. patient perspectives on major lower limb amputation – a qualitative systematic review. int j orthop trauma nurs. 2022;46:100958. doi:10.1016/ j.ijotn.2022.100958 10.hush j.m., cameron k., mackey m. patient satisfaction with musculoskeletal physical therapy care: a systematic review. phys ther. 2011;91(1):25–36. doi: 10.2522/ptj.20100061 11.keeffe m, cullinane p, hurley j, leahy i, bunzli s, o'sullivan p.b, et al. what influences patient-therapist interactions in musculoskeletal physical therapy? qualitative systematic review and meta-synthesis. phys ther. 2016;96(5):609–622. doi: 10.2522/ptj.20150240 12.shih h.t, kubo m.m, horn l.d, gorton j.n, ferraro a.l, macleod t.d, et al. patient experience and perceived benefits of physical therapy after lower limb amputation in middle-aged and older adults. j. allied health. 2022;51(3):180-91. https://doi.org/10.33137/cpoj.v6i1.42093 8 lee d.j, gambale a, nisani m, miller c, leung e, rodgers m, et al. the ideal physical therapist from the perspective of individuals with limb loss. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.4. https://doi.org/10.33137/cpoj.v6i1.42093 canadian prosthetics & orthotics journal issn: 2561-987x the ideal physical therapist for limb loss lee et al., 2023 13.macleod td, stockert b. amputation rehabilitation and prosthetics curricula in pt professional education programs. j allied health. 2021;50(1):29-37 14.lee dj, veneri da. development and acceptability testing of decision trees for self-management of prosthetic socket fit in adults with lower limb amputation. disabil rehabil. 2018;40(9):1066-1071. doi:10.1080/09638288.2017.1286694 15.collins kl, linassi ag, zucker-levin a. a focus groupand patient-driven study to understand patients' and health care providers' perspectives on services for people with amputation. physiother can. 2021;73(3):244-251. doi: 10.3138/ptc-2019-0054 appendices appendix a a) rate your physical therapy experiences (overall): 0-5 (5 is the highest) b) rate and rank factors that influence your physical therapy experience i. location of therapy clinic ii. personality of therapist iii. one-on-one time spent with you iv. equipment available to use v. pt’s knowledge about limb loss rehab vi. pt’s knowledge of new prosthetic technology vii. pt’s relationship with prosthetist viii. involvement with amputee coalition ix. credentials of the pt x. number of persons with limb loss pt treats a month xi. specialized equipment xii. length of pt session xiii. home program xiv. cost of pt xv. other:______________ c) rate and rank barriers to physical therapy i. distance to clinic ii. transportation to the clinic iii. pt’s’ personality iv. lack of equipment v. pt’s lack of knowledge about limb loss rehab vi. pt’s lack of treating amps vii. pt’s lack of knowledge about new prosthetic technology viii. pt’s lack of relationship with prosthetist ix. cost of pt x. other:______________ d) rate and rank the importance of the pt’s knowledge i. knowledge of the prosthetic components ii. knowledge of gait training with a prosthesis iii. knowledge about donning and fitting the prosthesis iv. knowledge about problem-solving issues with the fit of the prosthesis v. knowledge of knowing when to contact prosthetist vi. knowledge of current research regarding limb loss e) do you believe you would have benefited from more, less, or the same amount of physical therapy rehabilitation? appendix b 1. what is/was your experience with physical therapy in regard to your limb loss? 2. in your opinion, what made or makes a physical therapy experience positive for you? 3. in your opinion, what made or makes a physical therapy experience negative for you? 4. what are ways you believe physical therapy can be improved for persons with limb loss? 5. can you describe any things that your pt does or says that make them “ideal” for working with persons with limb loss? https://doi.org/10.33137/cpoj.v6i1.42093 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives zahedi s. review of prosthetics & orthotics needs for 21st century – vision for 2025. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.20. https://doi.org/10.33137/cpoj.v4i2.37113 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.37113 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 zahedi s. review of prosthetics & orthotics needs for 21st century – vision for 2025. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.20. https://doi.org/10.33137/cpoj.v4i2.37113 stakeholder perspectives review of prosthetics & orthotics needs for 21st century – vision for 2025 zahedi s* blatchford group, unit d antura, bond close, basingstoke, rg24 8pz, united kingdom. the context: a global challenge in lower limb prosthetics, there are 10 million amputees worldwide.1 there are estimated 10,000 practitioners each dealing with 400 patients in a year. this then only allows the needs of 4 million amputees to be addressed, leaving 6 million without access to care. who standards call for 4-5 professionals per million population. who’s recent figures of the disabled population stated 2.4 billion people need rehabilitation, assistive technology and mobility solutions. yet, the qualified groups of professionals in the p&o sector remain in the thousands, which is inadequate to meet the needs of the millions of patients needing care. with the rise of poverty worldwide, there is a need to use the limited healthcare resources more efficiently. validated and verified (health) economics tools, implemented within each country’s budget guides for best utilisation of resources, along with the deployment of appropriate technology, can guide decision-making on products and services with assured outcomes. the opportunity: digital health in prosthetics, socket comfort remains at the heart of the lower limb amputee rehabilitation prosthetic challenge. the interface with the residuum needs to be addressed based on real, objective science. this connection of socket to residual limb is, itself, a joint that dynamically moves and changes shape and volume due to skeletal bone movement inside muscles, tendon and skin soft tissue.2,3 digital tools should be using algorithms developed from, and based upon, dynamic input from sensors at the interface with the residuum measuring shear and compression forces and simultaneously to convert this information to simulate the movement of this unique joint. next, cancelling this movement perception by opposing actuating mechanisms, to create a perception of instantaneous rest (a direct skeletal fixation feel) in all dynamic conditions will bring deeper science to this last area of black magic.4 open access volume 4, issue 2, article no.20. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract what would we do, if only we had the power to go back?! the best way to consider this is to align and join all the known dots. to think of prosthetics and orthotics (p&o) as a system holistically centred around care of the user, identifying all their needs continuously, in their environment and in their lifestyle. this could produce a new value proposition for all multi-disciplinary team members by generating patient-centred therapeutic benefits and clinical outcomes that align all stakeholders in p&o towards using a common narrative, which makes decisions based on data. in this case, data is the outcome, using standards and instruments which are validated (e.g. www.amprom.uk) to quantify questions such as: “have we reduce risk of falls?”, “have we reduced risk of tissue injury?”, “have we reduced risk of low back pain?”, “have we reduced long term risk of osteoarthritis?”, etc. if we have, we are assured this will benefit the comfort and confidence for the user. we can have confidence in rehabilitation measured by improved stability and increased activity, and other measures which enable the accurate classification of products and services to match users. a prescription index, based on outcomes, could, for example, be calculated by a formula which accounts for the percentage reduction in falls probability, a patient satisfaction score, a mobility score and a quality-of-life score, allowing practitioners to base their choices of treatment pathways and component selection. this paper provides both the context for and contributing factors that make the proposing of such an objective prescription index an interesting thing to consider when discussing health economics in p&o. citation zahedi s. review of prosthetics & orthotics needs for 21st century – vision for 2025. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.20. https://doi.org/10.33137/cpoj.v4i2.37113 keywords prosthetic, systems, future integration, health economics effectiveness, rehabilitation, assistive devices, technology * corresponding author professor sir saeed zahedi, blatchford group, unit d antura, bond close, basingstoke, rg24 8pz, united kingdom. e-mail: saeed.zahedi@blatchford.co.uk orcid id: https://orcid.org/0000-0002-6959-632x special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.37113 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.37113 mailto:saeed.zahedi@blatchford.co.uk https://orcid.org/0000-0002-6959-632x 2 zahedi s. review of prosthetics & orthotics needs for 21st century – vision for 2025. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.20. https://doi.org/10.33137/cpoj.v4i2.37113 issn: 2561-987x prosthetics & orthotics needs for 21st century zahedi s., 2021 cpoj special s p e c ia l i s s u e data from smart liners with embedded sensors allow such objective measures to be collected. this enables both subjective and objective virtual assessment, with webbased accessibility allowing communication to an expert in any location around the globe to share knowledge and clinical experiences. this digital data is what is needed to create objective prescription indices to guide p&o decisionmaking. tele-medicine (for initial assessment, virtual triage, and final follow up) combined with hand held scanners, 3d additive manufacture printers, mobile centres for fitting, fabrication at remote satellite centres, and drone deliveries are already a reality.5,6 figure 1 shows a systems thinking model for continuous monitoring of patients that supports best function, creating rehabilitation pathways using local resources and allowing for experts’ experiences to be accessed for addressing issues. within this model, data collected can also be used to prevent costly tissue damage and to enable user participation in their rehabilitation. this is the collaborative way of addressing this major challenge. it is estimated over 50% of amputees need one socket or major adjustment per year at a treatment cost $10k, so working solutions to address this can result in considerable cost savings.5,7,8 figure 1: systems thinking: three health states needing different resources. (diagram from blatchford institute) a fundamental reality: health economics health economics plays a daily role in making decisions in all areas of health care. the american orthotics and prosthetics association (aopa) understood this when engaging the rand corporation to carry out the microprocessor controlled knee (mpk) project to produce a report for use in justification of equivalent models.9 this in turn set in motion the uk’s national health service’s mpk policy and leads the narrative on health economics/costbenefit/future business models in p&o that are linked to outcome measures.10 based on evidence, these works are being used for policy making decisions and developing technology road maps. some examples of the measures used to support decision making in the above process are: quality adjusted life year (qaly) the qaly is a healthcare measure that takes into account both the quantity and quality of life. one qaly indicates one year of perfect health. additional qalys provided by a given intervention, b, compared to an existing treatment, a, is calculated by the difference in utility scores for each intervention for a given year (determined from certain patient-reported outcome measures, such as eq-5d-5l or sf36) multiplied by the number of years, over which the treatment is being considered. financial cost though not a patient health consideration, inevitably the financial cost of a new, innovative intervention will always be considered. in particular, it will be compared to the cost of existing, alternative treatments and must be weighed against the potential for patient benefit. incremental cost-effectiveness ratio incremental cost-effective ratio (icer) is a means of factoring both patient benefit and fiscal burden into a single metric. it is calculated as the ratio of the difference financial cost between the new treatment and the existing one, to the qalys added by the new treatment. 𝐼𝐶𝐸𝑅 = 𝐶𝑜𝑠𝑡𝐵 − 𝐶𝑜𝑠𝑡𝐴 𝑡𝑖𝑚𝑒. (𝑈𝑡𝑖𝑙𝑖𝑡𝑦𝐵 − 𝑈𝑡𝑖𝑙𝑖𝑡𝑦𝐴) in the rand study,9 icer was used to do a cost effectiveness comparison of mpks with other commonly funded medical procedures (figure 2). also added is data reported on another prosthetics intervention: osseointegration11 (oi). costs for oi have been converted from the originally reported 2016/17 australian dollars to 2016 us dollars (1 aud : 0.76 usd) to aid comparison with other reported data.9 potential future disruptor: osseointegration while there are tools and measures such as the qaly that can be used to objectively evaluate current technology and processes, new techniques such as oi have the potential to be very disruptive to the status quo. as work progresses on this, members of the prosthetics working group of the international standards organization (iso) are in process of setting an iso subgroup to look at fail safe mechanism new patient new patient healthy minor issue major issue https://doi.org/10.33137/cpoj.v4i2.37113 3 zahedi s. review of prosthetics & orthotics needs for 21st century – vision for 2025. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.20. https://doi.org/10.33137/cpoj.v4i2.37113 issn: 2561-987x prosthetics & orthotics needs for 21st century zahedi s., 2021 cpoj special s p e c ia l i s s u e requirement specifications, test methods and test loads for osseointegration. the first subgroup workshop on this topic was organised with the assessment research centre (arc) at the university of melbourne where it was demonstrated that a variety of failsafe mechanism designed by different organisations had been done so with little reference to structural safety load standards used in lower limb prosthetics. all manufacturers are now keen to work together to establish a common standard to reduce rate of mechanical failures and protect users. this will, in time, will lead to a common procedure for selection, standard surgical operating procedures and post-operative care that will reduce risk of implant failures.12 once oi is an established rehabilitation pathway, it will open up a whole new dimension in system thinking in lower limb (already envisioned by some of the organisation in upper limb), as the direct route to connectivity to physiological nerves and muscles is provided. this will also have an impact on the economics of prosthetic care throughout the lifetime of the patient. figure 2: incremental cost-effectiveness ratio comparison of microprocessor prosthetic knees (mpk), osseointegration (oi), total knee angioplasty (tka), and prophylactic cardioverter defibrillator implantation (pcdi). all values in 2016 usd9,11. (diagram from blatchford institute) an unaddressed need: education technology and digital health at affordable prices needs to be the facilitator and robust science must replace the black magic upon which much of our current understanding of p&o is based. furthermore, this must be done with the support of p&o educators. currently most p&o educators are simply asking if their courses are fit for purpose – which is to support and maintain the status quo. it must be asked critically and answered with honesty: • will the graduates of 2025 have the right knowledge to meet the global challenges they will face? • will they know how to reduce the risk of tissue injury? • will they understand the effect of pressure, shear and moisture on the residual limb interface? • will they be able to use objective data? (e.g. by correctly reading and interpreting data provided by innovative measurement systems) • will they be able to use the results to make clinical, design and fit decisions? • will the p&o practitioner have the knowledge and skills to treat the socket to residuum interface as a joint and be able to manage the bone movement inside soft tissue? • how will they integrate sensors in a new product (that can detect and adjust the interface device independently) into their practices in a way that is also economically viable? all this, and more, becomes new material to be integrated into the curriculum if educators are to prepare the clinicians of the future for the technology of product and services together, which will be arriving as early as 3-5 years from now. in adopting them, these technologies need to be justified by health economics/cost-benefit/future business models in p&o and must be linked to outcome measures that are based on evidence. this is crucial for policy making decision and continued development of the technology road map. one way of describing this future model is a future of “servitisation”, which is the integration of product and services together. customised to individual need, it is made in a bespoke manner. an example of what this model could look like is shown in figure 3. p&o educators have a role to play in including such new ways of structuring into what we know and what the data tells us. we can integrate this into existing health economics and care models such as (for example) a “pillars of health care” approach. in lower limb prosthetics, the four pillars for heath economic evidence are reducing the risk of falls, tissue injury, lower back pain and osteoarthritis (figure 4). doing so requires not only new models and data, but also e-documentation, generating new data supporting the pillars of evidence based practice. -20 -10 0 10 20 30 40 50 60 70 80 mpk oi tka pcdi ic e r ( $ 0 0 0 s ) icer v other medical procedures prosthetics other medicine cost-effective threshold range https://doi.org/10.33137/cpoj.v4i2.37113 4 zahedi s. review of prosthetics & orthotics needs for 21st century – vision for 2025. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.20. https://doi.org/10.33137/cpoj.v4i2.37113 issn: 2561-987x prosthetics & orthotics needs for 21st century zahedi s., 2021 cpoj special s p e c ia l i s s u e figure 4: educational need for future “servitisation” – a four pillars model for lower limb prosthetics using validated patient reported outcomes (diagram from blatchford institute) a black swan? acceleration by covid industry moving towards a digital health cloud-based system is well on the way. the vision of 2020 has most recently been accelerated by the 2020-2021 global covidvirus pandemic. in the uk, the system interface gateways are already in the advanced stage with nhsx (www.nhsx.nhs.uk) which is overseeing the digitization of the nhs in partnership with other healthcare providers building the required infrastructure. accelerated by covid, investors are increasingly looking to opportunities with medical technology and more specifically devices with apps, whose usage is becoming a core part of care. virtual assessment in p&o services and online triage are going to stay in this new world and will be harnessed as part of cost-rationalisation. this is more necessary than ever as pressure of budgets on healthcare and the extra cost of advances in technology, compel all stakeholders to look to cut out waste, increase productivity and become leaner. the review of prosthetic services is already taking place in uk, re mapping the provision for next 10 years. the global community response to the who gate project1 expands the opportunity in their call for care of the world’s 1billion disabled people and acknowledges that addressing mobility needs via assistive technology will become an even greater challenge, with millions more people with disability to be caused by covid-19. there already exists an insufficient number of clinicians to cater to 60% of cases across the world,1 so there remains a challenge for all with respect to responding to this global need. the gap between 3d scanning to capture residuum shape cad cam software to make adjustments and rectifications additive manufacturing creates socket delivery at home, reducing required clinical visits sensors in e-prosthesis remotely monitor activity and status internet-based web app clinic alerted; appt request sent to patient by sms data captured and transmitted by smartphone anonymous data stored on opensource internet database figure 3: “servitisation” model for local/satellite and central fabrication. pilot study illustration from movaid13 four key secondary healthcare issues of prosthesis users https://doi.org/10.33137/cpoj.v4i2.37113 5 zahedi s. review of prosthetics & orthotics needs for 21st century – vision for 2025. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.20. https://doi.org/10.33137/cpoj.v4i2.37113 issn: 2561-987x prosthetics & orthotics needs for 21st century zahedi s., 2021 cpoj special s p e c ia l i s s u e developed and developing nations will become even wider. a corresponding rise of poverty rates will make achieving un sustainable development goals even harder. with increasing private investors ownership of p&o companies, longer term vision may suffer, but there is more potential for capital investment to respond to these challenges with viable solutions. changes already underway more recently, there has been a move by many suppliers to central fabrication and utilisation of 4th industrial revolution technology for sustainability of logistic supply chain and delivery improvement. central fabrication was the standard method of services some 40 years ago. with advances in engineering, the shift from a craft-based system to industrial systems, the creation of modular assembly prostheses & orthoses, in the last century there was a divergence and separation of product and services. the craft-based technician capable of fitting a patient became the clinical prosthetists and orthotists, who were trained and educated in universities and colleges resulting in the generation of degree-qualified education of p&o healthcare professionals, who have served our communities. the evolution of technology is now again converging product and services. this requires a review of current education and training. it must be asked: is the current education a fit for future? does it align with future requirement of multidisciplinary team care of disabled population? does it meet industry and health care needs? any suppliers who only provide services are finding it difficult to grow. the suppliers of p&o components are now developing products and technology where the designed and manufactured products must be directly fitted to patients, matched objectively to the user in shape, form, activity and lifestyle. the only thing that is not changing and remains certain is the how all these parameters will be changing. the future holds customisation and bespoke devices which are made to measure to fit and with embedded technology. devices that sense changes and automate the process of scheduling replacements and which will, eventually, automatically adjust themselves in response to change, are all part of the future of p&o care. regulatory evolution with increasing globalisation and reliance on technical solutions, there is a need for safety, as well as policing against rogue players and the development of a level playing field. the emergence of evidence-based practice and the required evolution of validated and verified outcome measures are critical to protect the patient. documentation of mitigation of risks and decision-making, as well as continuous monitoring, feeding continuous development is rapidly becoming a standard procedure across all medical industries. p&o will not be exempt. the emergence of the eu medical devices regulations (mdr)14 replacing previous directive in europe, and its alignment with fda in north america, will all be sitting on a platform of medical quality international standards. all stakeholders must be preparing for and expecting compliance. these changes will require clinicians, by law, to assess risk versus benefit and to make decisions based on previously collected and systematically reviewed objective evidence. call to action 1) adoption of a “pillars of health” model, as described above the pillars must be defined by and supported by evidencebased data supported criteria and must be economically justifiable. those responsible for making this happen are all the authorities, organizations and persons in power in p&o sector 2) making changes to p&o education p&o educators must be educating p&o students to be able to adopt digital tools and digital ways of thinking. graduates must be able to make decisions based on evidence supported by data, where that data is comprised of outcome, standards and instruments, that are validated, in order to quantify what has been done. this will ensure that all decisions are based on data and economic justification. they must also understand: how the data inform and support the pillars of healthcare, the relationship between economics, regulation and policy, and how each will be changed by the digitisation of healthcare. the educational outcome must be a practitioner that uses the same narrative across all of p&o sector. finally, as technology and digital health’s costs go down and become available at an affordable price, there is a need for a graduate who can act as a facilitator for future rehabilitation and robust science a model that must replace the current craft model. this cannot be achieved without the support of p&o educators. acknowledgements support of dr mcgrath head of blatchford institute in preparing above diagram and reviewing health economic analysis and dr moser through discussion leading to formulation of ideas, european commission for horizon 2020 movaid grant and team and partners on this project is greatly acknowledged. declaration of conflicting interests i am an employee of blatchford. sources of support there are no external financial support. horizon 2020 eu grant 2014-2017 https://doi.org/10.33137/cpoj.v4i2.37113 6 zahedi s. review of prosthetics & orthotics needs for 21st century – vision for 2025. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.20. https://doi.org/10.33137/cpoj.v4i2.37113 issn: 2561-987x prosthetics & orthotics needs for 21st century zahedi s., 2021 cpoj special s p e c ia l i s s u e references 1.priority assistive products list [internet]. world health organization (who). [cited 2021 may 7]. available from: https://www.who.int/publications/i/item/priority-assistive-productslist 2.tang j, mcgrath m, laszczak p, jiang l, bader dl, moser d, et al. characterisation of dynamic couplings at lower limb residuum/socket interface using 3d motion capture. med eng phys. 2015;37:1162–8. doi: 10.1016/j.medengphy.2015.10.004 3.tang j, mcgrath m, hale n, jiang l, bader d, laszczak p, et al. a combined kinematic and kinetic analysis at the residuum/socket interface of a knee-disarticulation amputee. med eng phys. 2017;49:131–9. doi: 10.1016/j.medengphy.2017.08.014 4.ispo uk member’s society socket technology workshop report [internet].2019; [cited 2021 may 7]. available from: https://www.ispo.org.uk/resources/1559900611_sockettechnology-workshop-25-april-2019---final-report.pdf 5.ispo symposium on telehealthi [internet]. spo webinar 2020: tele medicine in po. [cited 2021 may 7]. available from: https://www.ispoint.org/news/530460/ispo-symposium-ontelehealth.htm 6.un unido [internet]. united nations industrial development organization, 2021; [cited 2021 may 7]. available from: https://www.unido.org/ 7.datta d, vaidya sp, alsindi z. analyses of prosthetic episodes in trans-tibial amputees. prosthet orthot int. 1999;23:9–12. doi: 10.3109/03093649909071605 8.nair a, hanspal rs, zahedi ms, saif m, fisher k. analyses of prosthetic episodes in lower limb amputees. prosthet orthot int. 2008;32:42–9. doi: 10.1080/03093640701610615 9.liu hh, chen c, hanson ma, chaturvedi r, mattke s, hillestad r. economic value of advanced transfemoral prosthetics [internet]. santa monica, ca: rand corporation, 2017. [cited 2021 may 7]. available from: https://www.rand.org/pubs/research_reports/rr2096.html 10.clinical commissioning policy: microprocessor controlled prosthetic knees [internet]. nhs england, 2016; [cited 2021 may 7]. available from: https://www.england.nhs.uk/wpcontent/uploads/2016/12/clin-comm-pol-16061p.pdf 11.frossard la, merlo g, burkett b, quincey t, berg d. costeffectiveness of bone-anchored prostheses using osseointegrated fixation: myth or reality? prosthet orthot int. 2018;42(3):318–27. doi: 10.1177/0309364617740239. 12.ispo osseointegration seminar report [internet]. ispo, 2018; [cited 2021 may 7]. available from: https://www.ispo.org.uk/resources/20180308---ispoosseointegration-seminar-report---final.pdf 13.movement assisting devices [internet]. movaid project. [cited 2021 may 7]. available from: www.movaid.eu 14.regulation (eu) 2017/745 of the european parliament and of the council of 5 april 2017 on medical devices, amending directive 2001/83/ec, regulation (ec) no 178/2002 and regulation (ec) no 1223/2009 and repealing council directives 90/385/eec and 93/42/eec [internet]. off j europ uni. 2017; [cited 2021 may 7]. available from: http://eur-lex.europa.eu/legalcontent/en/txt/?uri=celex%3a32017r0745 author scientific biography professor sir saeed zahedi has over 40 years of experience in the field of prosthetics and he and his team have created outstanding results for many thousands of amputees around the world, giving them back the opportunity to live their lives to the fullest. he was responsible for the commercialisation of the first intelligent prosthesis in the early 1990s and the world’s first fully integrated limb system, linx, in 2014. in 2018 queens birthday honours list, he was named to receive a knighthood for his outstanding services to innovation and engineering in the field of rehabilitation. sir saeed is a multi-award winning author and presenter of over 170 papers, books and scientific publications and over 60 patents. he works for blatchford, a global company who develops and manufactures orthopaedic products that offer the best possible mobility, function, comfort and cosmetics after amputation or other pathology. for over 130 years, blatchford has been involved in provision of services, design and development of assistive technologies for mobility. their main focus has been enabling independence and social participation for lower limb amputees and real living for people with neuromuscular conditions. the reward has been witnessing renaissance in application of technology that has transformed lives. a fellow of the royal academy, 2018 honorary fellow of the institute of mechanical engineers, special commendation in the prince philip designer prize in 2011 and rsa royal designer for industry in 2013. he and his team were the winner of us medical design excellence award, german design award in 2017 following their 2016 mc roberts’s engineering award (gold medal and finalists in the 2010) adding to their 4th queens awards for technological achievement. in 2014 he received bhta life time achievement award, and the team is eef 2013 winner of winners, for smart product and export. in 2017 he received aopa life time achievement award. working on integration (products+services = servitization) in prosthetics and orthotics. https://doi.org/10.33137/cpoj.v4i2.37113 https://www.who.int/publications/i/item/priority-assistive-products-list https://www.who.int/publications/i/item/priority-assistive-products-list https://www.ispo.org.uk/resources/1559900611_socket-technology-workshop-25-april-2019---final-report.pdf https://www.ispo.org.uk/resources/1559900611_socket-technology-workshop-25-april-2019---final-report.pdf https://www.ispoint.org/news/530460/ispo-symposium-on-telehealth.htm https://www.ispoint.org/news/530460/ispo-symposium-on-telehealth.htm https://www.unido.org/ https://www.rand.org/pubs/research_reports/rr2096.html https://www.england.nhs.uk/wp-content/uploads/2016/12/clin-comm-pol-16061p.pdf https://www.england.nhs.uk/wp-content/uploads/2016/12/clin-comm-pol-16061p.pdf https://www.ispo.org.uk/resources/20180308---ispo-osseointegration-seminar-report---final.pdf https://www.ispo.org.uk/resources/20180308---ispo-osseointegration-seminar-report---final.pdf http://www.movaid.eu/ http://eur-lex.europa.eu/legal-content/en/txt/?uri=celex%3a32017r0745 http://eur-lex.europa.eu/legal-content/en/txt/?uri=celex%3a32017r0745 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 research article ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.35070 1 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 research article investigation of localized skin temperature distribution across the transtibial residual limb ghoseiri k1,2, allami m3, murphy j.r4, page p5, button d.c1,4* 1school of human kinetics and recreation, memorial university of newfoundland, st. john’s, newfoundland, canada. 2department of orthotics and prosthetics, school of rehabilitation sciences, hamadan university of medical sciences, hamadan, iran. 3janbazan medical and engineering research center (jmerc), tehran, iran. 4faculty of medicine, memorial university of newfoundland, st. john’s, newfoundland, canada. 5department of physical therapy, franciscan university, baton rouge louisiana, usa. introduction critical factors in the successful use of a prosthesis include skin integrity of the residual limb, skin health, and skin hygiene.1,2 skin irritation, ulceration, dermatitis, and excessive sweating are common complaints of amputees who use prostheses for their daily activities.3,4 heat and moisture that become trapped inside the socket lead to a jeopardizing, unpleasant, and infectious environment for amputees, which dramatically decreases the quality of life, satisfaction and use of the prosthesis, and social participation.3,5,6 in dysvascular and neuropathic patients, any area of the skin with 2ºc or more increased temperature than adjacent areas has an increased risk of ulceration7; therefore, localized skin temperature is an indicator of a potential skin breakdown. the transtibial residual limb (trl) skin temperature measurements with the prosthesis demonstrated unequal heat buildup over different anatomical locations.8,9 various scenarios are conceivable for unequal heat buildup over the open access volume 4, issue 1, article no.2. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: interventions to resolve thermal discomfort as a common complaint in amputees are usually chosen based on the residual limb skin temperature while wearing prosthesis; whereas, less attention has been paid to residual limb skin temperature while outside of the prosthesis. the objective of this study was to explore the localized and regional skin temperature over the transtibial residual limb (trl) while outside of the prosthesis. methodology: eight unilateral transtibial adults with traumatic amputation were enrolled in this crosssectional study. participants sat to remove their prostheses and rested for 30 minutes. twelve sites were marked circumferentially in four columns (anterolateral, anteromedial, posteromedial, and posterolateral) and longitudinally in three rows (proximal, middle, and distal) over the residual limb and used for attachment of analog thermistors. skin temperature was recorded and compared for 11 minutes. furthermore, the relationship of skin temperature with participants’ demographic and clinical characteristics was explored. findings: the whole temperature of the trl was 27.73 (sd=0.83)°c. there was a significant difference in skin temperature between anterior and posterior columns. likewise, the distal row was significantly different from the proximal and middle rows. the mean temperature at the middle and distal zones of the anteromedial column had the highest and lowest skin temperatures (29.8 and 26.3°c, p<0.05), respectively. the mean temperature of the whole trl had no significant relationships (p>0.05) with participants’ demographic and clinical characteristics. conclusions: an unequal distribution of temperature over the trl was found with significantly higher and lower temperatures at its anterior column and distal row, respectively. this temperature pattern should be considered for thermoregulation strategies. further investigation of the residual limb temperature with and without prosthesis, while considering muscles thickness and blood perfusion rate is warranted. article info received: november 8, 2020 accepted: december 31, 2020 published: january 12, 2021 citation ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i 1.35070 keywords amputees, skin temperature, thermography, amputation stumps, artificial limbs, prosthesis design, residual limb * corresponding author: duane c button, phd school of human kinetics and recreation, memorial university of newfoundland, st. john’s, newfoundland, canada. e-mail: dbutton@mun.ca orcid: https://orcid.org/0000-0001-6402-8545 https://doi.org/10.33137/cpoj.v4i1.35070 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.35070 https://doi.org/10.33137/cpoj.v4i1.35070 mailto:dbutton@mun.ca https://orcid.org/0000-0001-6402-8545 2 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 issn: 2561-987x investigation of localized skin temperature distribution ghoseiri et al. 2021 cpoj trl. a scenario could be referred to as the heterogeneous structure of the trl, consisting of different underlying tissues with different thicknesses, blood perfusion rates, metabolic activities, and thermal characteristics.9 in another scenario, it could be referred to as socket and liner insulating nature, their materials characteristics, and their fit issues that may lead to higher frictions at the interface with the skin.6,10 therefore, thermal discomfort with prostheses is not solely related to the socket and liner. previous investigations were mostly focused on controlling the temperature while prostheses were donned. thus, most techniques for dealing with heat buildup addressed heat issues for inside prostheses. recently, some developments in prosthetic components have been done to address thermal discomfort inside prostheses. for instance, the silcare breathe cushion (blatchford, uk) and soft skin air (uniprox, germany) are perforated liners that permit air and moisture transfer from skin to the outer surface of the liner.11,12 likewise, the smarttemp liner (the ohio willow wood, usa) has phase-change material inside its silicon structure, which permits energy storage and release in response to increased and decreased temperature, respectively. temperature storage happens by changing the physical state from solid to liquid, whereas temperature release happens reversely.13 thermoregulatory systems are smart components that could be mounted on prosthetic sockets. some thermoregulatory systems were introduced in prior research with promising outcomes that could be commercialized once their electric power and weight issues are being resolved.14,15 however, to resolve thermal discomfort in people with trl through prosthetic development, a comprehensive knowledge of temperature distribution over the residual limb is required.11,14-16 understanding the baseline temperature distribution over the trl without any external intervention such as socket or liner, may facilitate prosthetic design and technological development around natural residual limb temperature. skin temperature of trl could be investigated using temperature sensors, thermography cameras, and virtual methods (i.e., mathematical modeling of the residual limb) during rest and activity.5,8,9,17-19 temperature recording using thermistors is a complicated process inside the prosthesis. it needs control of the ambient temperature and mitigation of potential intervening parameters like inconsistent socket and liner characteristics, internal/external pressure on sensors, sensor wire breakdowns, movement artifacts, and decalibration. therefore, measuring trl skin temperature without prosthesis donned may provide more accurate, reliable results. interestingly, few studies have measured trl skin temperature without a prosthesis despite the more extensive literature about heat buildup inside the prosthesis.19-21 perhaps such studies could provide a better understanding and insight into thermal discomfort in people with amputation. although rarely investigated in people with amputation, some temperature control techniques and exercises for able-bodied people22 could be used in people with transtibial amputation pending baseline temperature distribution over the residual limb. furthermore, different study designs and unique characteristics of the amputee population make it difficult to compare the results between studies; therefore, further investigation of the trl thermal pattern is needed. the present study aimed to establish a baseline of the trl temperature distribution while the prosthesis was removed. in addition, relationships among demographic and clinical characteristics with residual limb temperature were explored. methodology participants eight male veterans were enrolled in this study based on a purposive sampling method. a list of all potential veterans with transtibial amputation living in the hamadan province of iran was excerpted and provided by the veterans and martyrs affair foundation (vmaf) from their comprehensive national database of about 500,000 iranian veterans and martyrs.23 all veterans who met the study inclusion criteria were invited by a phone call to participate in this study. the inclusion criteria were: (1) unilateral trl with at least 25 cm length from knee axis, (2) traumatic amputation, (3) age between 18-60 years, (4) at least two years of experience of prosthesis use, (5) existence of intact skin of the residual limb without any ulceration based on medical examination. the exclusion criteria were (1) existence of any medical comorbidities that may alter sensation/ thermoregulation (e.g., neurological, cardiovascular, and endocrine), (2) smoking for at least 30 minutes before starting the experiment,24 (3) alcohol drinking and medication use on experiment day, (4) impaired thermal sense in the residual limb based on clinical examination,25 (5) use of antiperspirant sprays, powder, and lotions on the skin of the residual limb on experiment day. after a full description of the study aims and procedures, written informed consent was obtained from participants before enrollment. all aspects of the study were approved by the ethics committee of the hamadan university of medical sciences (ir.umsha.rec.1394.333). temperature measurement over the transtibial residual limb twelve sites were marked circumferentially in four columns (anteromedial, anterolateral, posteromedial, and posterolateral) and longitudinally in three rows (proximal, middle, and distal) over the residual limb to provide attachment sites of thermistors.8 attachment sites were longitudinally labeled z1 to z3 from proximal to distal and https://doi.org/10.33137/cpoj.v4i1.35070 https://www.blatchford.co.uk/products/silcare-breathe-cushion-liner/ https://www.softskinair.com/ https://www.willowwood.com/products-services/liners/transtibial/alpha-smarttemp-liner-featuring-outlast/ 3 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 issn: 2561-987x investigation of localized skin temperature distribution ghoseiri et al. 2021 cpoj were marked at a constant distance to each other (figure 1). in the longitudinal view, the distance from the knee center to the distal end of the residual limb was measured for each patient, divided by four to determine the appropriate distance between sensors. in the circumferential view, two columns of sensors were considered in the anterior and two in the posterior part of the residual limb. columns were located on major muscle masses in line with prior similar studies.5,17 a portable thermoregulatory system designed, fabricated, and tested in a previous study was used for data collection.20 twelve analog ntc (negative temperature coefficient nxft15xh103, murata manufacturing co. ltd., japan) thermistors were calibrated and then attached to the skin using adhesive tape.20 each thermistor was wired to a small amplifier board and connected to the input port of an arduino duemilanove (arduino, italy) microcontroller board. a seven volts lithium-ion battery with a nominal capacity of 2.2 ah was used to supply the necessary power for thermistors and the microcontroller. figure 1: temperature measurement sites over the transtibial residual limb experimental setup all data collection was done on three consecutive days, from 8 a.m. to 1 p.m. participants sat to remove their prosthesis and rested for 30 minutes to become familiar with the laboratory environment and adapt to the ambient temperature. demographic and clinical characteristics of participants were collected, and inclusion/exclusion criteria were verified. thermistors were then attached to the marked sites over the residual limb. during one session, the localized skin temperature of the residual limb was recorded for 11 minutes at the ambient temperature of 23°c. data and statistical analysis statistical analyses were computed using ibm spss software (version 22.0, ibm corp, new york, ny). the normality distribution of temperature data was assessed and determined by the shapiro-wilk test. the mean temperature of the residual limb was calculated at each zone compared to the mean temperature at other anatomical zones. also, the overall temperature of the residual limb was determined. the grand mean or pooled mean, which was the mean of all residual limbs’ average temperature, was calculated. the mean temperature at each zone was compared to the residual limb's mean temperature and the grand mean temperature using onesample t-tests. levene's test for homogeneity of variances was explored between columns and rows over the trl. since there were equal variances, parametric one-way analysis of variance (anova) was used to examine the variability of temperature in columns and rows. tukey post hoc analysis was used to identify differences among columns, as well as circumferential rows. pearson’s correlation coefficient and partial eta squared were calculated to explore the potential relationship of the residual limb's average temperature with quantitative and nominal characteristics of participants. significance for all data was defined as p<0.05, and all data are reported as mean ± sd (standard deviation). results demographic and clinical characteristics of participants twenty-eight veterans volunteered to participate and attended a pre-screening of their adaptability with the inclusion/exclusion criteria. twenty veterans were excluded from the study because of the existence of skin irritation of the residual limb (n=3), uptaking medications (n=6), associated medical comorbidities (n=9), and applying lotion over the skin of the residual limb (n=2). therefore, all tests were done with eight veterans. the demographic and clinical characteristics of participants are presented in table 1. participants had a mean age of 40.3 (sd=8.4) years. for employment status, fifty percent of participants were employed and had a job; the remaining participants were retired or unemployed and received compensation and pension from vmaf based on their disability rating. the average time after amputation and experience of using a prosthesis were 19.3 (sd=9.6) and 18.9 (sd=9.8) years, respectively. exoskeletal prosthesis use was the same as endoskeletal prosthesis among participants; however, polyfoam liner was more popular than silicon/gel liners. average daily prosthesis use was 10 (sd=3.5) hours. posterior viewanterior view z1 z1 z1 z1 z2z2 z3z3z3z3 z2z2 lateral medial lateral https://doi.org/10.33137/cpoj.v4i1.35070 4 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 issn: 2561-987x investigation of localized skin temperature distribution ghoseiri et al. 2021 cpoj table 1: the demographic characteristics of participant veterans (n=8) e: employed; *un-e: unemployed (retired or unemployed veterans and veterans who received compensation and pension from veterans and martyrs affair foundation (vmaf) based on their disability rating considered unemployed); r: right side; l: left side; ex-p: exoskeletal with polyfoam liner; en-p: endoskeletal with polyfoam liner; en-s: endoskeletal with silicone/gel liner. temperature measurement over the transtibial residual limb figure 2 shows the localized mean temperature at different anatomical zones. the highest temperature was recorded at the middle portion of the anteromedial region of the trl. the lowest temperature was recorded at the distal end of the anteromedial part of trl (figure 2). the mean, sd, and se (standard error) of the skin temperature recorded by the thermistors for each zone are presented in table 2. the mean temperature of the residual limb and the grand mean temperature of all residual limbs were calculated and shown in table 2. the grand mean of the skin temperature for all residual limbs was 27.7°c. there was no significant difference between the mean temperature at each zone and the whole residual limb’s temperature. whereas, the comparison between the grand mean temperature of all residual limbs and the mean temperature at each zone indicated a significant difference in four zones (figure 3). the variability of the mean temperature was significant among four columns (f(3,92)=6.09, p=0.001), as well as three rows (f(2,93)=5.69, p=0.005). the tukey post hoc analysis showed that the columns and rows could respectively be categorized into two distinct temperature regions (table 3). for the longitudinal columns, there was no significant difference between the anteromedial and anterolateral columns. likewise, there was no significant difference between the posteromedial and posterolateral columns. however, there was a significant difference between the anterior and posterior columns. for the circumferential rows, the distal row had a significant difference from the proximal and middle rows. however, there was no significant difference between the middle and proximal rows. figure 2: average of the recorded temperature (°c) at each anatomical zone over the trl, and the highest (red) and lowest (blue) temperature zones. relationship of average residual limb temperature with clinical and demographic characteristics of participants table 4 presents the correlation data between average residual limb skin temperature with participant demographic and clinical characteristics. there was no significant relationship between average residual limb temperature and participants’ demographic or clinical characteristics. discussion the present study focused on the temperature measurement of the trl while outside of the prosthetic socket. on average, lower residual limb temperature was found compared to a previous similar study.20 uneven temperature distribution over the trl was found, which followed a specific thermal gradient pattern. the highest and lowest skin temperatures were recorded at the middle and distal zones of the anteromedial region of trl, respectively. skin temperature recording showed that the anterior part of the residual limb had significantly higher skin temperature compared to its posterior part. similarly, the distal part of the residual limb had a significantly lower temperature than its middle and proximal parts. variable data range mean standard deviation (sd) age 23-51 40.3 8.4 weight (kg) 60-92 75.8 8.8 height (cm) 165-178 170.6 4.3 bmi (kgm-2) 19.6-31.8 26.1 3.5 time after amputation (y) 4-30 19.3 9.6 years of prosthesis use (y) 3-30 18.9 9.8 daily prosthesis use (h) 7.5-18 10 3.5 employment status e: n=4 *un-e: n=4 amputation side r: n=5 l: n=3 type of prosthesis ex-p: n=4 en-p: n=3 en-s: n=1 posterior viewanterior view 29.1 29.2 26.8 27.9 26.927 26.726.926.327.8 29.828.4 lateral medial lateral https://doi.org/10.33137/cpoj.v4i1.35070 5 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 issn: 2561-987x investigation of localized skin temperature distribution ghoseiri et al. 2021 cpoj table 2: the recorded temperature by the twelve thermistors, their mean and sd per zone and participant, and temperature comparison between the grand mean of all residual limbs and mean temperature at each zone. case id regional residual limb temperature whole residual limb temperature anterolateral anteromedial posteromedial posterolateral z1 z2 z3 z1 z2 z3 z1 z2 z3 z1 z2 z3 mean sd se t 1 p 1 27.8 27.7 26.4 28.4 28.8 24.8 27.4 27.6 24.8 27.1 26.1 24.8 26.8 1.4 0.4 0 1 2 28 27.9 26.6 27.7 29.6 26.5 29.2 26.5 24.8 27.5 24.4 24.3 26.9 1.7 0.5 0 1 3 30.6 26.6 28.5 31.1 29.6 28 24.7 25.7 28 27.7 26.8 27.1 27.9 1.9 0.5 -0.1 1 4 29.2 29.3 26.7 28.2 29 25.5 27 24.4 26.5 28.4 25.8 25.2 27.1 1.7 0.5 0 1 5 30 29.3 27.9 30 29.8 25.9 24.1 27.8 26.4 29.8 28.5 27.7 28.1 1.9 0.5 0 1 6 29.7 28.8 28.7 28.8 29.8 26.8 29 26.8 27.1 28.6 27.6 27.3 28.2 1.1 0.3 0.2 0.9 7 27.8 29.4 27.2 28.4 30.2 25.8 26.5 27.2 26.3 26.3 26.8 26.9 27.4 1.3 0.4 0 1 8 29.7 28.5 30.5 31.1 31.9 27.1 26.7 29.4 31.4 28.2 28.9 30.4 29.5 1.7 0.5 0 1 mean 29.1 28.4 27.8 29.2 29.8 26.3 26.8 27 26.9 27.9 26.9 26.7 27.7 0.8 sd 0.1 0.9 1.3 1.3 0.9 0.9 1.7 1.4 2 1 1.4 1.8 se 0.4 0.3 0.5 0.5 0.3 0.4 0.6 0.5 0.7 0.4 0.5 0.7 t 2 3.6 2.1 0.2 3.2 6.4 -4 -1.4 -1.4 -1.1 0.6 -1.6 -1.4 p 0.01* 0.08 0.85 0.02* 0.00* 0.01* 0.21 0.20 0.33 0.54 0.15 0.20 z: zone; sd: standard deviation; se: standard error; t1: one sample t statistics in comparison to mean temperature of the residual limb; t2: one sample t statistics in comparison to the grand mean temperature of all residual limbs; p: p-value; *: the difference is statistically significant (p<0.05). table 3: the recorded temperature (mean±sd) at each region over the residual limb columns anteromedial anterolateral posteromedial posterolateral f(3,92) p-value 28.4(sd=1.5) 28.4(sd=0.5) 26.9(sd=0.1) 27.2(sd=0.5) 6.1 0.001 rows proximal middle distal f(2,93) p-value 28.3(sd=1.6) 28.0(sd=1.7) 26.9(sd=1.7) 5.7 0.005 classification of temperature sites based on their column and row (note: sites under each class have no significant difference with each other. however, there is a significant difference (p<0.05) between classes) temperature in columns temperature in rows class 1 class 2 class 1 class 2 anteromedial posteromedial zone 1: proximal zone 3: distal anterolateral posterolateral zone 2: middle https://doi.org/10.33137/cpoj.v4i1.35070 6 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 issn: 2561-987x investigation of localized skin temperature distribution ghoseiri et al. 2021 cpoj temperature measurement over the transtibial residual limb uneven temperature distribution over trl was found. the highest temperature (29.8 (sd=0.9)°c) was recorded in the middle part of the anteromedial (z2) of trl. the lowest temperature (26.3 (sd=0.9)°c) was recorded at the distal part of the anteromedial (z3) of trl. transtibial amputation is associated with the shortened length of the lower limb, which directly affects the amount of heat transfer by conduction and radiation. likewise, the less surface area of the lower limb leads to reduced temperature transfer by evaporation. furthermore, compromised muscles and blood vessels have lower potential in temperature transfer by convection. therefore, different thermal patterns over the trl could be anticipated compared to the sound limb. for instance, the highest and lowest temperature sites over the trl are closer to each other than those shown by gatt et al. in sound limbs using a thermography camera.26 the distance between the highest and lowest skin temperature would be highlighted whenever the temperature difference passes a physiological safe limit, leads to thermal discomfort, and jeopardizes skin integrity.5, 27 figure 3: the mean value of the recorded temperature at each zone over the residual limb (*: the difference is statistically significant (p<0.05) based on one sample t-test in comparison of the grand mean of all residual limbs’ temperature and the mean temperature at each zone). s ki n t e m p e ra tu re ( c ) 32 30 28 26 24 22 a n te ro la te ra l z 1 a n te ro la te ra l z 2 a n te ro la te ra l z 3 a n te ro m e d ia lz 1 a n te ro m e d ia lz 2 a n te ro m e d ia lz 3 p o st e ro m e d ia l z 1 p o st e ro m e d ia l z 2 p o st e ro m e d ia l z 3 p o st e ro la te ra lz 1 p o st e ro la te ra lz 2 p o st e ro la te ra lz 3 mean+sd mean mean-sd table 4: correlation of average residual limb temperature with clinical & demographic characteristics of participants. statistics value clinical & demographic characteristics quantitative¥ nominal ǂ a g e ( y ) m a s s ( k g ) h e ig h t (c m ) t im e a ft e r a m p u ta ti o n ( y ) y e a rs o f p ro s th e s is u s e (y ) d a ily p ro s th e s is u s e (h ) p ro s th e s is t y p e e m p lo y m e n t s ta tu s a m p u ta ti o n s id e residual limb temperature correlation 0.45 0.33 -0.07 0.56 0.55 0.30 0.15 0.28 0.16 p 0.27 0.42 0.88 0.15 0.16 0.48 0.66 0.18 0.32 ¥: pearson’s r ǂ: partial eta square https://doi.org/10.33137/cpoj.v4i1.35070 7 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 issn: 2561-987x investigation of localized skin temperature distribution ghoseiri et al. 2021 cpoj comparison of temperature recording of the trl in the current study with previous studies5,8,17,20 is difficult considering the difference in thermography protocol. as earlier indicated, we recorded temperature while the residual limb was outside of a prosthetic socket. however, in previous studies, the temperature recording of the trl was performed when the residual limb was inside the prosthetic socket. our findings are comparable to the baseline phase of the thermography protocol in the ghoseiri et al. study. they measured residual limb skin temperature in a single transtibial amputee. they found that the middle part of the anterolateral region of the trl showed the highest skin temperature, whereas the distal part of the posterior region of the residual limb showed the lowest skin temperature.20 in line with our results, they showed uneven temperature distribution over the trl skin, revealed warmer anterior columns than posterior ones, and spotted the colder region of the trl at its distal end than the proximal end. however, the location of the warmest and coldest sites differs from the current study. this disagreement could be attributed to the difference in study designs and the number of recording sensors. ghoseiri et al. recorded temperature in a reversal single-subject design with six thermistors over the trl skin.20 the highest and lowest temperature sites of the trl in those studies recorded temperature inside the socket were different from our findings. peery et al. reported that the proximal anterior region of the residual limb was the coldest site and the posterior region of the residual limb was the warmest site.8 klute et al. found that the middle part of the anterolateral location of the residual limb had the warmest temperature, while the posteromedial part of the distal end of the trl had the coldest temperature.5 in the current study, the whole trl's average temperature was 27.7 (sd=0.8)°c, ranging from 27 to 31°c. this temperature was lower than the average temperature reported by ghoseiri et al., 29.1 (sd=0.6)°c,20 probably because of the difference in study design and the number of thermistors. although difficult to do this comparison, the average temperature of the whole trl in current study was lower than amounts reported for inside socket thermography protocols, 29.5 (sd=0.9)°c,17 31.0 (sd=1.5)°c,5 and 31.4 (sd=1.3)°c,8 probably because of the insulating characteristics of the prosthetic socket and liner that contributed to higher residual limb temperature, as well as temperature measuring following periods of activity. it was reported that localized higher skin temperature than the adjacent parts is a predictor of skin damage.27 therefore, maintenance or provision of a constant temperature, thermoregulation, by keeping a relatively constant temperature and heating or cooling mechanisms could ensure optimal physiological health and function.28 thermoregulation can be induced internally (e.g., by changes in the blood flow during vasodilation or vasoconstriction)29 or externally (e.g., thermoregulatory systems and exercise maneuvers).20 with respect to the external thermoregulation, the pattern of temperature distribution over the trl may be useful for selecting appropriate thermoregulatory strategies both in and out of the prosthesis. challenges in developing a thermoregulatory system include managing the size, weight, cost, and required power to efficiently work when applied as a prosthetic component.5,20 therefore, for both in and out of prosthesis approaches, the distinct skin temperature measurements based on column and row could help to select the best attachment sites of thermoregulatory systems. our findings revealed that the anteromedial and posteromedial columns of the residual limb were the warmest and coldest regions, respectively, while the anterior part of the trl had higher temperature compared to the posterior part. furthermore, the proximal and middle circumferential rows had higher temperature compared to the distal row. therefore, to provide a thermal equilibrium, i.e., balance between the rate of heat production and rate of heat release, out of the prosthesis, a cooling mechanism may be required for the proximal and middle rows of the anterior part of the residual limb, while a heating mechanism may be necessary for the distal and posterior parts of the residual limb. for instance, therapeutic exercises which showed promising cooling effects in ablebodied people could be modified and used in people with amputation. however, this concept needs further investigation. thermal standards in able-bodied people are based on both environmental (e.g., air temperature, air velocity, radiant temperature, and relative humidity) and personal factors (e.g., activity level, metabolic rate, the weighted average of skin temperature, and clothing insulation).29,30 in people with amputation, the residual limb skin temperature is generally greater than in able-bodied people because of the decreased surface area of the body and changes in blood circulation and the volume and shape of the residual limb muscles.21,31 interestingly, the distal end of the residual limb in unilateral amputees is cooler than the corresponding site on the contralateral sound side, probably due to less blood flow, damaged vessels, fat accumulation, and more skin surface due to amputation consequences.9,21 therefore, because of many different factors between able-bodied and amputees, thermal standards available for able-bodied people cannot be used for people with amputation. relationship of the average residual limb temperature with demographic and clinical characteristics of participants statistical analysis revealed small non-significant relationships between the whole residual limb temperature and participants’ demographic and clinical characteristics. this finding could highlight the importance of the socket barrier and physical activity in increasing the residual limb https://doi.org/10.33137/cpoj.v4i1.35070 8 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 issn: 2561-987x investigation of localized skin temperature distribution ghoseiri et al. 2021 cpoj skin temperature.3 indeed, our thermography protocol of temperature recording at the rest condition and outside of a prosthetic socket leads to opposite findings against the general belief that age, lifestyle, and physical condition by impacting the metabolism and perfusion rate of the blood alters temperature distribution pattern of the trl9 and thermal discomfort.18 we found that the middle part of the anteromedial region of the residual limb had an over 2°c temperature difference with the residual limb's mean temperature; therefore, this site may have a higher vulnerability to thermal discomfort and skin irritation. with increasing age, the thermal sense may be decreased, and some older persons may not detect up to 4°c of temperature change.32 however, thermal sense quantification differs from skin temperature recording and is beyond the scope of the present study. although the present study had no focus on participants' thermal comfort, klute et al. reported an increase of 2°c could cause thermal discomfort in people with amputation.5 in contrast, diment and colleagues noted that thermal discomfort in lower limb prosthetic users is not directly related to the skin temperature.33 similar to localized trl skin temperature, there is no consensus about thermal comfort in people with amputation. the interaction of residual limb skin temperature with demographic and clinical characteristics could affect the quality of life in people with amputation. thus, it needs further investigation, probably around residual limb tissue characteristics. study limitations several aspects may threaten the internal and external validity of this study. evaluating residual limb temperature is difficult because the thermistors are connected to a computer or microcontroller using small and breakable wires, likely leading to small sample sizes in the previous temperature measurement studies in amputees.5,8,17,20 for instance, the sample size in peery et al., klute et al., huff et al., and ghoseiri et al. were 5, 9, 1, and 1, respectively.5,8,17,20 the small sample size and purposive sampling of male adult traumatic (war-related) amputees may limit the generalizability of the results to females and those who suffered amputation following dysvascularity and other etiologies. future studies may assess thermoregulatory mechanisms such as skin perfusion or thermal receptor activation. skin and muscle thickness were not evaluated in this study, which may influence results in two different ways. high skin thickness could decrease heat transfer by conduction, which potentially leads to reduced surface temperature. in contrast, the increased muscle thickness could imply more metabolic rate, higher temperature production, and higher power for pumping blood in the vascular system, all associated with higher skin temperature. therefore, future research may use musculoskeletal ultrasound to quantify the soft tissue thickness of the residual limb. although it is beyond the scope of the present study, from a surgical standpoint, there are two primary techniques for transtibial amputation, i.e., myodesis and myoplasty, which respectively being indicated for traumatic and dysvacular amputees. in myodesis, muscle attaches to the bone, while in myoplasty, muscle sutures to another muscle. therefore, there would be some difference in the length-tension relationship of the muscles and blood flow rate at the residual limb.34 thus, an investigation of the chosen amputation technique on trl temperature distribution is warranted. a direct comparison between residual and sound limbs on the same participant would expand the baseline knowledge of temperature distribution in trl. conclusion this study may provide important information to develop thermoregulatory strategies for the residual limb in transtibial amputees, ranging from prosthetic socket design, component manufacturing, and material selection to potential therapeutic exercises. thermoregulatory strategies need to address the unequal skin temperature distribution over the trl while outside the prosthetic socket. provision thermal equilibrium needs cooling and heating mechanisms for anterior and posterior regions of the trl, respectively. likewise, a heating mechanism for the distal part, and cooling mechanisms for the middle and proximal parts of the trl. temperature recording revealed that the highest and lowest skin temperatures were located at the middle and distal zones of the anteromedial region of trl, respectively. thus, localized thermoregulatory strategies could address heating/cooling mechanisms to prevent thermal-related skin irritation. further thermoregulatory investigations (both in and out of the socket) with larger sample sizes and inclusion of different groups of people with transtibial amputation are warranted; these studies should consider the volume and thickness of the skin and muscles, as well as the blood perfusion rate at different regions of the residual limb. acknowledgements the authors would like to sincerely thank the financial support of the vice-chancellor for research and technology, hamadan university of medical sciences (no. 950304954). moreover, the authors would like to thank the veterans and martyrs affairs foundation for their cooperation with the study. declaration of conflicting interests the authors declare that they have no competing interests, author contribution kamiar ghoseiri: contributed to the study concept and design, participated in data gathering, analyzed and interpreted data, https://doi.org/10.33137/cpoj.v4i1.35070 9 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 issn: 2561-987x investigation of localized skin temperature distribution ghoseiri et al. 2021 cpoj contributed to the drafting of the manuscript and read and approved the final manuscript. mostafa allami: contributed to the study concept and design, participated in data gathering, contributed to the drafting of the manuscript and read and approved the final manuscript. justin r. murphy: analyzed and interpreted data, contributed to the drafting of the manuscript and read and approved the final manuscript. phillip page: analyzed and interpreted data, contributed to the drafting of the manuscript and read and approved the final manuscript. duane c. button: contributed to the study concept and design, analyzed and interpreted data, contributed to the drafting of the manuscript and read and approved the final manuscript. sources of support this material was based on the work supported by the vicechancellor for research and technology, hamadan university of medical sciences (no. 950304954). ethical approval all aspects of the study were approved by the ethics committee of the hamadan university of medical sciences (ir.umsha.rec. 1394.333). after a full description of the study aims and procedures, written informed consent was obtained from participants before enrollment. references 1.hachisuka k, nakamura t, ohmine s, shitama h, shinkoda k. hygiene problems of residual limb and silicone liners in transtibial amputees wearing the total surface bearing socket. arch phys med rehabil. 2001;82(9):1286-90. doi: 10.1053/apmr.2001.25154 2.butler k, bowen c, hughes am, torah r, ayala i, tudor j, et al. a systematic review of the key factors affecting tissue viability and rehabilitation outcomes of the residual limb in lower extremity traumatic amputees. j tissue viability. 2014;23(3):81-93. doi: 10.1016/j.jtv.2014.08.002 3.ghoseiri k, safari mr. prevalence of heat and perspiration discomfort inside prostheses: literature review. j rehabil res dev. 2014;51(6):855-68. doi: 10.1682/jrrd.2013.06.0133 4.meulenbelt he, geertzen jh, dijkstra pu, jonkman mf. skin problems in lower limb amputees: an overview by case reports. j eur acad dermatol venereol. 2007;21(2):147-55. doi: 10.1111/j.1468-3083.2006.01936.x 5.klute gk, huff e, ledoux wr. does activity affect residual limb skin temperatures? clin orthop relat res. 2014;472(10):3062-7. doi: 10.1007/s11999-014-3741-4 6.klute gk, rowe gi, mamishev av, ledoux wr. the thermal conductivity of prosthetic sockets and liners. prosthet orthot int. 2007;31(3):292-9. doi: 10.1080/03093640601042554 7.chambers rb, elftman n, bowker jh. orthotic management of the neuropathic and/or dysvascular patient. in: hsu jd, michael jw, fisk jr, editors. aaos atlas of orthoses and assistive devices. 4th edition ed. philadelphia, usa: mosby elsevier; 2008. 8.peery jt, ledoux wr, klute gk. residual-limb skin temperature in transtibial sockets. j rehabil res dev. 2005;42(2):147-54. doi: 10.1682/jrrd.2004.01.0013 9.peery jt, klute gk, blevins jj, ledoux wr. a three-dimensional finite element model of the transibial residual limb and prosthetic socket to predict skin temperatures. ieee trans neural syst rehabil eng. 2006;14(3):336-43. doi: 10.1109/tnsre.2006. 881532 10.li w, liu xd, cai zb, zheng j, zhou zr. effect of prosthetic socks on the frictional properties of residual limb skin. wear. 2011;271(11):2804-11. doi: 10.1016/j.wear.2011.05.032 11.mcgrath m, mccarthy j, gallego a, kercher a, zahedi s, moser d. the influence of perforated prosthetic liners on residual limb wound healing: a case report. can prosthet orthot j. 2019;2(1). doi: 10.33137/cpoj.v2i1.32723 12.uniprox. softskin air: unique prosthetic solutions; [internet] 2020 [cited 2020 december, 16]. available from: https://www.softskinair.com/. 13.wernke mm, schroeder rm, kelley ct, denune ja, colvin jm. smarttemp prosthetic liner significantly reduces residual limb temperature and perspiration. j prosthet orthot. 2015;27(4): 1349. doi: 10.1097/jpo.0000000000000070 14.nurhanisah mh, jawaid m, ahmad azmeer r, paridah mt. the aircirc: design and development of a thermal management prototype device for below-knee prosthesis leg socket. disabil rehabil assist technol. 2019;14(5):513-20. doi: 10.1080/17483107.2018.1479782 15.ghoseiri k, zheng yp, hing ll, safari mr, leung ak. the prototype of a thermoregulatory system for measurement and control of temperature inside prosthetic socket. prosthet orthot int. 2016;40(6):751-5. doi: 10.1177/0309364615588343 16.klute gk, bates kj, berge js, biggs w, king c. prosthesis management of residual-limb perspiration with subatmospheric vacuum pressure. j rehabil res dev. 2016;53(6):721-8. doi: 10.1682/jrrd.2015.06.0121 17.huff ea, ledoux wr, berge js, klute gk. measuring residual limb skin temperatures at the skin-prosthesis interface. j prosthet orthot. 2008;20(4):170-3. doi: 10.1097/jpo.0b013e 3181875b17 18.segal ad, klute gk. residual limb skin temperature and thermal comfort in people with amputation during activity in a cold environment. j rehabil res dev. 2016;53(5):619-28. doi: 10.1682/jrrd.2015.03.0053 19.cutti ag, perego p, fusca mc, sacchetti r, andreoni g. assessment of lower limb prosthesis through wearable sensors and thermography. sensors (basel). 2014;14(3):5041-55. doi: 10.3390/s140305041 https://doi.org/10.33137/cpoj.v4i1.35070 10 ghoseiri k, allami m, murphy j.r, page p, button d.c. investigation of localized skin temperature distribution across the transtibial residual limb. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.2. https://doi.org/10.33137/cpoj.v4i1.35070 issn: 2561-987x investigation of localized skin temperature distribution ghoseiri et al. 2021 cpoj 20.ghoseiri k, zheng yp, leung akl, rahgozar m, aminian g, masoumi m, et al. temperature measurement and control system for transtibial prostheses: single subject clinical evaluation. assist technol. 2018;30(3):133-9. doi: 10.1080/10400435.2016. 1272070 21.harden rn, gagnon cm, gallizzi m, khan as, newman d. residual limbs of amputees are significantly cooler than contralateral intact limbs. pain pract. 2008;8(5):342-7. doi: 10.1111/j.1533-2500.2008.00216.x 22.fortney sm, vroman nb. exercise, performance and temperature control: temperature regulation during exercise and implications for sports performance and training. sports med. 1985;2(1):8-20. doi: 10.2165/00007256-198502010-00002 23.allami m, soroush m. what priorities should be considered for iranian veterans with ankle-foot injuries? a health needs assessment study, 25 years post-conflict. mil med res. 2017;4(1):28. doi: 10.1186/s40779-017-0137-2. 24.redisch w, sheckman e, stelle jm. skin temperature response of normal human subjects to various conditions. circulation. 1952;6(6):862-7. doi: 10.1161/01.cir.6.6.862 25.mumenthaler m, mattle h. the neurological examination. in: taub e, editor. fundamentals of neurology. stuttgart: georg thieme verlag; 2006. p. 36. 26.gatt a, formosa c, cassar k, camilleri kp, de raffaele c, mizzi a, et al. thermographic patterns of the upper and lower limbs: baseline data. int j vasc med. 2015;2015; doi:10.1155/2015/831369. 27.bergtholdt ht. temperature assessment of the insensitive foot. phys ther. 1979;59(1):18-22. doi: 10.1093/ptj/59.1.18 28.tansey ea, johnson cd. recent advances in thermoregulation. adv physiol educ. 2015;39(3):139-48. doi: 10.1152/advan.00126. 2014 29.mehnert p, malchaire j, kampmann b, piette a, griefahn b, gebhardt h. prediction of the average skin temperature in warm and hot environments. eur j appl physiol. 2000;82(1-2):52-60. doi: 10.1007/s004210050651 30.simion m, socaciu l, unguresan p. factors which influence the thermal comfort inside of vehicles. energy procedia. 2016;85:472-80. doi: 10.1016/j.egypro.2015.12.229 31.benedict fg, miles wr, johnson a. the temperature of the human skin. proceedings of the national academy of sciences of the united states of america. 1919;5(6):218-22. doi: 10.1073/pnas.5.6.218 32.florez-duquet m, mcdonald rb. cold-induced thermoregulation and biological aging. physiol rev. 1998;78(2): 339-58. doi: 10.1152/physrev.1998.78.2.339 33.diment le, thompson ms, bergmann jhm. comparing thermal discomfort with skin temperature response of lower-limb prosthesis users during exercise. clin biomech (bristol avon). 2019;69:14855. doi: 10.1016/j.clinbiomech.2019.07.020 34.taylor bc, poka a. osteomyoplastic transtibial amputation: technique and tips. j orthop surg res. 2011;6:13. doi: 10.1186/1749-799x-6-13. https://doi.org/10.33137/cpoj.v4i1.35070 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 research article hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.36059 1 hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 research article evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface hamilton m1,2, sivasambu h2, behdinan k3, andrysek j1,2 * 1 institute of biomedical engineering, faculty of applied science and engineering, university of toronto, toronto, canada. 2 bloorview research institute, holland bloorview kids rehabilitation hospital, toronto, canada. 3 department of mechanical and industrial engineering, faculty of applied science and engineering, university of toronto, toronto, canada. introduction pressure sensing in mobility assistive technology (mat) can inform the fitting of patient-customized devices such as prostheses and orthoses. for example, lower-limb prosthetic setup can take multiple weeks from the first to the final optimized fitting.1 each fitting session features both static (i.e. standing) and dynamic (i.e. walking) weightbearing assessments, where the clinician relies on their visual perception and fitting experience, as well as patient feedback to iteratively refine the fit and function of the device.1 both static and dynamic assessments provide critical information, however dynamic assessments provide more pertinent information related to everyday mobility use.2 the integration of pressure-sensing into the mat can help to quantify pressures at the mat-body interface, affording clinicians more objective assessments, and thus improving overall fit and performance of the device.3,4 there are several commercially available interfacial pressure sensors, with varying technologies such as forcesensitive resistors, strain gauges, quantum tunneling composites, strain gauges and others.5,6 most studies evaluating these sensors focus on static testing. the few sensor evaluation studies that have examined dynamic loading conditions, do not closely characterize the patterns of walking.7–9 parmar et al. and khodasevych et al. used 10 open access volume 4, issue 1, article no.4. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: pressure sensing at the body-device interface can help assess the quality of fit and function of assistive devices during physical activities and movement such as walking and running. however, the dynamic performance of various pressure sensor configurations is not well established. objective(s): two common commercially available thin-film pressure sensors were tested to determine the effects of clinically relevant setup configurations focusing on loading areas, interfacing elements (i.e. ‘puck’) and calibration methods. methodology: testing was performed using a customized universal testing machine to simulate dynamic, mobility relevant loads at the body-device interface. sensor performance was evaluated by analyzing accuracy and hysteresis. findings: the results suggest that sensor calibration method has a significant effect on sensor performance although the difference is mitigated by using an elastomeric loading puck. both sensors exhibited similar performance during dynamic testing that agree with accuracy and hysteresis values reported by manufacturers and in previous studies assessing mainly static and quasi-static conditions. conclusion: these findings suggest that sensor performance under mobility relevant conditions may be adequately represented via static and quasi-testing testing. this is important since static testing is much easier to apply and reduces the burden on users to verify dynamic performance of sensors prior to clinical application. the authors also recommend using a load puck for dynamic testing conditions to achieve optimal performance. article info received: february 19, 2021 accepted: may 8, 2021 published: may 19, 2021 citation hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i 1.36059 keywords calibration, interface pressure, pressure sensor, pressure measurement, prosthetics, repeatability, sensor evaluation * corresponding author: jan andrysek, phd bloorview research institute, holland bloorview kids rehabilitation hospital, toronto, canada. email: jandrysek@hollandbloorview.ca orcid: https://orcid.org/0000-0002-4976-1228 https://doi.org/10.33137/cpoj.v4i1.36059 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.36059 https://doi.org/10.33137/cpoj.v4i1.36059 mailto:jandrysek@hollandbloorview.ca https://orcid.org/0000-0002-4976-1228 2 hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 issn: 2561-987x dynamic performance of interfacial pressure sensors hamilton et al. 2021 cpoj cycles of load application with 30 seconds on and 30 seconds off to simulate dynamic wear of a prosthesis.6,10 however, the typical walking cycles are much more dynamic repeating at approximately one hertz (hz) frequency.11 hence, the mobility-relevant dynamic performance of interfacial pressure sensors remains to be established. aside from the loading patterns, previous research has shown that performance can greatly vary depending on the way a sensor is configured in its sensing application.9,10 the force-resistance relationship of a thin film sensor depends on factors such as sensor shape, geometry, and design, as well as the way by which the forces are applied to the sensor.12 in fact, sensor manufacturers recommend that sensors be tested and calibrated under conditions that closely match their application.12 however, this is difficult to do for mat applications, due to the complex nature of the interface. for example sensor manufacturers recommend that the area of applied load be held constant at an area slightly smaller than the sensors’ sensing area.12–14 however, such conditions are not representative of the dynamic conditions of a body-device interface, where the loading area fluctuates and typically is larger than the sensing area. sensor performance has been shown to vary with the area of applied load, however, testing has not been performed under dynamic conditions,15 despite well documented differences in sensor performance under static and dynamic conditions.16 previous research with piezoresistive sensors has reported a trade-off between the dynamic performance (hysteresis error) and the static sensitivity, as increased stiffness will alter the viscoelastic behavior causing hysteresis and reduce static sensitivity.17–19 commercially available pressure mapping systems designed specifically for the mat-body interface, such as the f-socket, utilize an array of sensors to provide pressure profiles over a large portion of the interface. however, these systems have limited clinical usage since they can be costly, bulky, cumbersome to apply, and suffer from performance issues including failure due to creasing; there is also a lack of information about their dynamic performance.5,18 as such, current understanding of dynamic performance of sensors in mat-representative interfaces is limited, thus restricting the effective use of these sensors. the overall objective of this study was to evaluate the effects of previously identified setup conditions (load area and presence of an elastomeric interface ‘puck’) on the dynamic performance of two common commercial pressure sensors. a sub-objective of the study was to understand the effects of two calibration techniques on sensor performance, including calibrating under matched-area (ma) and simplified, generalized-area (ga) conditions. as such, this study aimed to establish conditions and protocols that simulate dynamic testing of interfacial pressure sensors at the body-device interface, and empirically inform the use of the sensors for improved performance. methodology testing was performed to assess the effect of area of applied load and sensor calibration method on sensor dynamic performance under two loading configurations: with and without a puck. the puck causes the force applied to the sensor to be concentrated over a particular area of the sensor.12 sensors this study was performed on two commercially available sensors, the qtc™ sp200-10 sensor (peratech ltd, richmond, north yorkshire, uk) and the thrumode™ fsr (sensitronics, bow, wa, usa). these sensors were selected due to their high performance and broad use in other studies.6,10 table 1 displays sensor specifications. table 1: sensor model specifications parameter qtc™ sp200-10 half inch thrumode™ fsr manufacturer peratech ltd. sensitronics inc. sensing diameter (mm) 10 12.7 thickness (mm) 0.45 0.43 claimed operating range (n) 0.1 to 20 0.26 to 26a single part repeatability (%) n/ab 5 part-to-part repeatability (%) 4.5 15 a reported as 0.3 – 30 psi, converted to n using sensing area. b not reported. data acquisition system time and force data were collected using the instron bluehill universal software. resistance values were collected using a keithley 6500 6 ½ digit multimeter (dmm) (tektronix, inc., beaverton, or, usa) and tektronix’s proprietary kickstart software (tektronix, inc., beaverton, or, usa). all data were collected at 500 hz. resistance, force, and time data were analyzed using matlab v19 (the mathworks, inc., natick, ma, usa). testing apparatus an apparatus designed to simulate human tissue developed in a previous study evaluating pressure sensors under static conditions was used in this study.15 a 2 cm layer of soft translucent silicone (renew® silicone 10, renew®, easton, pa, usa), shown to mimic behavior of human tissue,20-22 was placed over the instron base platen. an instron 5944 universal testing system with a 100 n load cell (instron, norwood, ma, usa) applied loads up to 10 n. this force range was selected as it is within both sensor’s working range and represents forces and pressures applied at the body-device interface in various biomedical applications.23, 24 https://doi.org/10.33137/cpoj.v4i1.36059 3 hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 issn: 2561-987x dynamic performance of interfacial pressure sensors hamilton et al. 2021 cpoj loading tip attachments (contact diameters of 5 mm, 8 mm, 15 mm, and 25 mm) were 3d-printed (pla white material; ultimaker 2 printer; ultimaker b.v., netherlands) and pressfit to the instron’s upper compression platen. the 8 mm tip adhered to manufacturer recommendations for minimum coverage of fsr sensing area (i.e., load applicator 20% smaller than sensing diameter of sensor).12 this sizing prevented interactions with the spacer and adhesive surrounding the sensing area, while ensuring much of the sensing element was activated. the 5 mm tip represented conditions when a portion of the sensing area is loaded (e.g., point load). clinically relevant conditions in which the loading area surpasses the sensing area are represented by the 15and 25-mm diameter tips. to understand the effects of sensor configuration, a loading puck was used as per sensor manufacturers’ recommendations under half of the conditions tested.12 a silicone loading puck (1.5 mm thickness, 8mm diameter, and durometer 60 shore a hardness) guaranteed the force was transferred entirely through the sensing area. the effect of the loading puck on the system’s phase and magnitude response was assumed to be negligible as the manufacturer recommends a silicone actuator to improve performance in cases of inconsistent force actuation;12 consistent responses with the loading puck were confirmed in pilot testing. previous work indicated the use of the loading puck and omission of a rigid backing produced the best repeatability for both sensors.15 figure 1 displays a photo of the setup and a labelled schematic indicating sensor configuration with the loading puck. protocol application conditions to evaluate the effects of load area and elastomer puck presence on sensor dynamic performance, a full factorial experiment was conducted using eight application conditions: four loading tip areas, both with and without an elastomer puck. the order of application conditions was randomized to minimize potential testing bias. sensor conditioning prior to testing each sensor, manufacturer guidelines for sensor conditioning were followed,13 in which 110% of the maximum test load (11 n) was applied to the sensor for 30 seconds, and then removed for 30 seconds. this cycle was repeated four times. sensor calibration prior to dynamic testing, a force sweep from 0 to 10 n was applied to the sensor at a loading rate of 0.67 n/s (i.e. loading duration of 15 s). this force sweep was repeated three times and the corresponding resistance and force data were curve-fit in matlab to characterize the sensor’s force-resistance curve for a given configuration (i.e. area and puck configuration).25 an exponential relationship (1) was selected to convert resistance output to pressure values for the subsequent tests based on manufacturer recommendations, literature, and best fit.12,25 𝑦 = 𝑎𝑥−𝑏 (1) figure 1: actual setup, labelled schematic showing configuration with loading puck, and photo of sensors: (i) sensitronics, (ii) peratech (i) (ii) silicone (tissue) elastomer loading puck sensor loading tip attachments of varying area f instron https://doi.org/10.33137/cpoj.v4i1.36059 4 hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 issn: 2561-987x dynamic performance of interfacial pressure sensors hamilton et al. 2021 cpoj two different calibration methods were used: ma and ga calibration techniques. though sensor manufacturers recommend calibration conditions that imitate sensor use, this is not always possible at the body-device interface (i.e., inconsistent actuation and area of applied load); showcasing the importance of the simplified ga calibration method. the ma calibration is a more accurate, timeconsuming method in which the exact configuration used during testing is matched during the calibration. the second method, ga calibration, is a time-saving approach where one configuration used during calibration is then applied to multiple configurations (i.e. different areas) during the experimental testing. for this study, both calibration methods were used to convert the same set of experimental data (sensor resistance) to force measurements, enabling a comparison between the used performance measures (i.e., normalized root-mean squared error (nrmse) and hysteresis error (he)). specifically, for the ma calibration, the calibration equation for each configuration was applied to the experimental data. for the ga calibration, only the calibration equation from the 8 mm puck was applied to each set of experimental data. sensor testing hysteresis testing hysteresis is the difference in sensor output at the same force when the sensor is being loaded and unloaded and is commonly used to assess the performance of fsrs.24,26 to understand the sensor’s dynamic performance and identify hysteresis effects, the sensor was loaded from 0 to 10 n and then unloaded to 0 n at rates of 10 n/s (duration of two seconds). this was repeated 3 times. this loading rate was selected to analyze the hysteresis effects under conditions similar to dynamic loading: one second each of loading and unloading in the test is comparable to the average gait cycle time of approximately one second.27 dynamic testing a square wave profile was applied to the sensor: loaded to 10 n, held for 1 second, unloaded to 0.5 n, held for 1 second, and repeated 10 times. the profile was intended to roughly approximate the weight bearing and non-weight bearing loading patterns during walking gait. analysis sensor performance was evaluated by analyzing accuracy and hysteresis. researchers identified these performance measures during the evaluation of an interface force/pressure sensor.10,28 accuracy errors, evaluated in both hysteresis and gait testing, was calculated using a normalized root-mean square error (nrmse). the nrmse, is calculated by dividing rmse by applied force of 10 n and then converting the value to a percentage (2): nrmse = rmse f ̅ ∗ 100% (2) hysteresis error (he) was calculated by taking the maximum difference in sensor output (loading versus unloading) for a given force level. the hysteresis difference, funloading – floading, was calculated at each force from 0.5 to 10 n at increments of 0.1 n. the equation used to calculate he (3): he = funloading − floading f ̅ ∗ 100% (3) the hysteresis error was normalized by dividing by the maximum force of 10 n, and then converted to a percentage. for each trial, the hysteresis error was calculated at the force with the greatest hysteresis difference. an additional measure of sensor performance was the coefficient of variation (cv).9,26 typically, clinical applications require a cv of less than 10%.6 an analysis of variance (anova) was used to compare the effects of calibration method and puck on the nrmse and he for each sensor model (i.e., peratech and sensitronics). all main effects, 2-way and 3-way interactions were evaluated with p<0.05 indicating significance. insignificant effects were then removed from the model, and significant main effects, 2 and 3-way interactions were reported. a paired t-test was performed on each set of results (i.e., nrmse, he) to quantify differences in sensor performance. jmp® pro 14 software was used (sas institute inc., cary, nc, usa). results dynamic hysteresis testing the force applied versus time plots for the peratech and sensitronics sensors are displayed in figure 2 and figure 3. the force applied versus force measured representing the hysteresis curves for the peratech and sensitronics sensors are displayed in figure 4 and figure 5. subplots are grouped by configuration: no elastomer puck (np) and with elastomer puck (yp); as well as calibration method: ma and ga. line colours distinguish the area of applied load, and line styles distinguish the trial number, as shown in the legend. nrmse and he values for the applications conditions are displayed in table 2. in figure 2 and figure 3, the applied force waveform is displayed in green on the plot, as indicated in the legend. these figures provide a visualization of the sensor’s accuracy in each configuration. overall, the peratech sensor exhibits higher accuracy than the sensitronics https://doi.org/10.33137/cpoj.v4i1.36059 5 hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 issn: 2561-987x dynamic performance of interfacial pressure sensors hamilton et al. 2021 cpoj sensor. the sensitronics sensor signal exhibits more noise. the addition of the puck shows a significant improvement in sensor accuracy, especially in the ga calibration data. without a puck, the ga calibration data accuracy reaches roughly 50% for the larger areas with both sensors. a dead band appears for the peratech sensor in the np condition with areas larger than the sensing area (15 and 25 mm), where no force is measured until approximately 3.5 n. in the ma calibration conditions, following the dead band, the data reaches 10 n because each data set was calibrated individually, with a different set of resistance values corresponding the force values for each configuration. overall, as seen in figure 4 and figure 5, the hysteresis error was significantly less for the peratech sensor, compared to the sensitronics sensor (p=0.01). for both sensors, the addition of the puck appeared to reduce hysteresis errors. the dead band described above can also be seen in these hysteresis plots. for both sensors, the nrmse is below 10% for the majority of cases, with most exceptions occurring under conditions without a loading puck at the larger areas. while the he is under 10% for most conditions for the peratech sensor, all the he values for the sensitronics sensor are above 10% recommended for use in clinical applications.6 table 2: hysteresis and nrmse results. config diameter (mm) peratech (%) sensitronics (%) ma calibration ga calibration ma calibration ga calibration nrmse he nrmse he nrmse he nrmse he np 5 2.6 ± 1.3 8.4 ± 1.7 32.8 ± 0.1 15.9 ± 4.6 5.4 ± 0.5 15.9 ± 1.4 7.8 ± 1.7 20.6 ± 2.8 8 2.0 ± 0.2 8.6 ± 0.4 2.0 ± 0.2 8.6 ± 0.4 5.4 ± 2.1 16.0 ± 4.5 5.4 ± 2.1 16.0 ± 4.5 15 11.1 ± 0.2 23.2 ± 15.3 46.8 ± 0.1 12.8 ± 3.9 9.9 ± 0.2 43.2 ± 8.6 57.3 ± 0.1 39.8 ± 14.6 25 11.0 ± 0.1 12.2 ± 1.6 52.2 ± 0.3 11.5 ± 4.2 11.7 ± 2.1 48.3 ± 7.3 54.9 ± 0.3 38.6 ± 13.2 yp 5 4.8 ± 0.4 13.4 ± 0.8 9.2 ± 1.0 15.2 ± 0.6 5.3 ± 1.6 16.8 ± 2.9 9.9 ± 0.4 18.7 ± 2.7 8 1.7 ± 0.4 7.8 ± 1.4 1.7 ± 0.4 7.8 ± 1.4 9.5 ± 0.9 25.4 ± 1.4 9.5 ± 0.9 25.4 ± 1.4 15 2.5 ± 0.2 9.5 ± 0.4 2.8 ± 0.2 8.0 ± 0.1 7.3 ± 1.8 19.8 ± 2.5 9.8 ± 0.7 20.9 ± 1.9 25 2.0 ± 0.3 8.8 ± 0.9 3.0 ± 0.1 6.6 ± 1.0 6.6 ± 2.2 19.0 ± 5.4 8.7 ± 1.1 22.4 ± 3.8 figure 2: force vs. time plots for two-second hysteresis tests for peratech sensor using ma and ga calibration methods. iii) np generalized-area calibration iv) yp generalized-area calibration legend (area-trial #) 05-1 05-2 05-3 08-1 08-2 08-3 15-1 15-2 15-3 25-1 25-2 25-3 applied force f o rc e ( n ) 8 6 4 2 0 10 f o rc e ( n ) 8 6 4 2 0 10 f o rc e ( n ) 8 6 4 2 0 10 f o rc e ( n ) 8 6 4 2 0 10 i) np matched-area calibration time (s) 0 0.5 1 1.5 2 ii) yp matched-area calibration time (s) 0 0.5 1 1.5 2 time (s) 0 0.5 1 1.5 2 time (s) 0 0.5 1 1.5 2 https://doi.org/10.33137/cpoj.v4i1.36059 6 hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 issn: 2561-987x dynamic performance of interfacial pressure sensors hamilton et al. 2021 cpoj figure 3: force vs. time plots for two-second hysteresis tests for sensitronic sensor using ma and ga calibration methods. i) np matched-area calibration ii) yp matched-area calibration iv) yp generalized-area calibrationiii) np generalized-area calibration f o rc e ( n ) 8 6 4 2 0 10 time (s) 0 0.5 1 1.5 2 f o rc e ( n ) 8 6 4 2 0 10 time (s) 0 0.5 1 1.5 2 f o rc e ( n ) 8 6 4 2 0 10 f o rc e ( n ) 8 6 4 2 0 10 time (s) 0 0.5 1 1.5 2 time (s) 0 0.5 1 1.5 2 figure 4: force measured vs. force applied plots for two-second hysteresis tests for peratech using ma and ga calibration methods. force applied (n) 0 2 4 6 8 10 f o rc e m e a s u re d ( n ) 5 0 10 force applied (n) 0 2 4 6 8 10 force applied (n) 0 2 4 6 8 10 force applied (n) 0 2 4 6 8 10 f o rc e m e a s u re d ( n ) 5 0 10 f o rc e m e a s u re d ( n ) 8 6 4 2 0 10 f o rc e m e a s u re d ( n ) 8 6 4 2 0 10 i) np matched-area calibration ii) yp matched-area calibration iii) np generalized-area calibration iv) yp generalized-area calibration n o te . r e fe r to g ra p h l e g e n d i n f ig u re 2 . n o te . r e fe r to g ra p h l e g e n d i n f ig u re 2 . https://doi.org/10.33137/cpoj.v4i1.36059 7 hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 issn: 2561-987x dynamic performance of interfacial pressure sensors hamilton et al. 2021 cpoj dynamic testing nrmse values for both sensors under the different application conditions are displayed in table 3. with the ma calibration method, the nrmse is below 10% for both sensors, meeting the desired threshold for accuracy in clinical applications.6 using the ga calibration method with a puck, the cv across the areas averaged 8.8 ± 3.8 % for both sensors. without a puck for the ga calibration method, cv values exceed 100% for the larger areas for both sensors. in the ga condition, similar trends showing the effects of the area can be seen in the hysteresis (table 2) and dynamic (table 3) results. in general, the nrmse is lowest for ga with matched areas (8mm diameter loading tip and 8mm sensor area) and accuracy is decreased with higher nrmse values for the smaller (5mm) diameter loading tip. this is most evident for the peratech sensor. nrmse is further increased for the two larger diameters (15 and 25mm). figure 5: force measured vs. force applied plots for two-second hysteresis tests for sensitronics using ma and ga calibration methods. i) np matched-area calibration ii) yp matched-area calibration iii) np generalized-area calibration iv) yp generalized-area calibration f o rc e m e a s u re d ( n ) 8 6 4 2 0 10 f o rc e m e a s u re d ( n ) 8 6 4 2 0 10 force applied (n) 0 2 4 6 8 10 force applied (n) 0 2 4 6 8 10 force applied (n) 0 2 4 6 8 10 force applied (n) 0 2 4 6 8 10 f o rc e m e a s u re d ( n ) 5 0 10 f o rc e m e a s u re d ( n ) 5 0 10 table 3: dynamic testing nrmse configuration area peratech sensor sensitronics sensor ma calibration ga calibration ma calibration ga calibration np 05 3.7 ± 1.3 112.9 ± 2.8 8.9 ± 1.6 6.8 ± 0.9 08 6.2 ± 0.3 6.2 ± 0.3 5.0 ± 0.8 5.0 ± 0.8 15 6.6 ± 0.8 118.0 ± 5.9 8.4 ± 0.4 317.9 ± 18.3 25 6.1 ± 0.2 558.3 ± 16.6 5.4 ± 0.6 185.6 ± 6.5 yp 05 4.8 ± 0.1 17.2 ± 0.0 4.2 ± 0.8 11.5 ± 1.3 08 4.9 ± 0.6 4.9 ± 0.6 6.8 ± 0.4 6.8 ± 0.4 15 3.7 ± 0.2 6.3 ± 0.3 5.9 ± 0.7 6.3 ± 0.8 25 2.9 ± 0.1 6.8 ± 0.5 7.3 ± 0.1 10.8 ± 1.2 n o te . r e fe r to g ra p h l e g e n d i n f ig u re 2 . https://doi.org/10.33137/cpoj.v4i1.36059 8 hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 issn: 2561-987x dynamic performance of interfacial pressure sensors hamilton et al. 2021 cpoj discussion this study aimed to uniquely establish the methods and baseline data for relevant setup and calibration configurations and testing under dynamic loading patterns, for two commonly used pressure sensors. the study applied dynamic testing conditions that, compared to previous work, were much more representative of patterns present in human walking gait. the findings suggest that both sensors exhibited similar performance during dynamic testing that agree with accuracy and hysteresis values reported by manufacturers and in previous studies assessing mainly static and quasi-static conditions. in addition, the calibration method was found to significantly influence sensor performance, although much less so when an elastomeric loading puck was applied to the sensor. researchers have cited hysteresis and accuracy as key requirements of a successful interfacial sensor, although performance under dynamic conditions is often a limitation.10,26 overall, the dynamic performance of the two commercial sensors is quite similar, however the peratech generally exhibited better performance (i.e. higher accuracy) with lower hysteresis and dynamic testing errors. the calibration method, as found in previous work, had a significant impact on the dynamic sensor performance.15 however, ga calibration can be used in place of ma calibration when using a loading puck to ensure the load is transmitted through the sensing area, regardless of the load applicator size. ga calibration is significantly easier and more practical to perform. the nrmse values reported in this study agree with the accuracy values reported in the study by parmar et al6 ranging from 94.8 to 96.0% (equivalent to an error of 4.0 to 5.2%) for the peratech sensor and 90.8 to 94.0% (equivalent to an error of 6.0 to 9.2%) for the sensitronics sensor. these values are within the range of the errors seen for the 8 mm loading tip applicator conditions using ma calibration. similarly, the hysteresis error observed for the peratech sensor with the 8 mm loading tip applicator conditions using ma calibration agrees with the manufacturer reported hysteresis error of 8.5%.29 finally, the cv of 8.8 ± 3.8% for dynamic testing with the loading puck agrees with previous works performing static testing under the same conditions (7.6 ± 3.6%).15these findings provide new evidence suggesting that the sensor performance is not adversely affected by dynamic loading that is at the frequencies relevant to mobility. it further suggests that the performance is sufficient for most clinical applications.6 previous studies have suggested potential performance trade-offs between static and dynamic performance,17,18,30 however for the sensors and conditions tested here this did not appear to be the case. in part this may be because the loading frequencies associated with gait mobility are not high enough to adversely affect dynamic performance. alternatively, the findings may be influenced by the type of sensor technology or material used. nevertheless, for gait related mat applications the findings have important implications on the utilization of the thin film sensors, suggesting that static testing and calibration as suggested by manufacturers might be adequately sufficient, without the need for further dynamic testing. this is important, since whereas static testing can simply be performed with a dead weight, dynamic testing requires specialized equipment that is not readily accessible. implementation of objective measures produced by pressure sensors and similar systems are typically confined to research settings due to their cost and lack of portability.31,32 however, the potential simplification of testing protocols and assurance of their relevance to dynamic testing, is important for feasibility in the case of the use of these sensors in research as well as clinical realms. a limitation to the study is the assumption of uniformity in tissue loading. testing performed included a uniform layer of silicone simulating tissue at the body-device interface. in real life, the anatomy of a limb includes inconsistencies in tissue properties and bony prominences that can affect compliance and curvature. additionally, effects of frictional shear forces, temperature, and curvature were not examined in this work, but have been shown to affect pressure measurements. additionally, it is possible that a portion of the measured errors may be associated with the dynamic response of the testing machine setup, rather than sensor performance. the limits of the sensors should also be explored in dynamic applications, including higher cycle frequencies. a faster cycle time, (i.e. 1 second instead of 2 seconds) would be more representative of the dynamics of normal gait. finally, the feasibility of incorporating a loading puck in a body-device interface or in an actual clinical application was not assessed here. future work will need to consider feasibility and performance of adding pucks, including their design (i.e. thickness, hardness) and effects on aspects such as comfort and application time. conclusion this study develops and tests a unique protocol for the dynamic testing of pressure sensors at the body-device interface, and addresses concerns with existing approaches including applicator size, loading profile, and sensor conditioning and calibration. overall, when using sensor configurations recommended by manufacturers both sensors exhibited performance sufficient for use in clinical applications. the foundational knowledge established by this work reveals that existing thin film pressure sensors may be a suitable tool for measuring pressures at the body device interface, such as prosthetic sockets and orthosis, and can do so for dynamic conditions such as gait. future https://doi.org/10.33137/cpoj.v4i1.36059 9 hamilton m, sivasambu h, behdinan k, andrysek j. evaluating the dynamic performance of interfacial pressure sensors at a simulated body-device interface. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.4. https://doi.org/10.33137/cpoj.v4i1.36059 issn: 2561-987x dynamic performance of interfacial pressure sensors hamilton et al. 2021 cpoj work in this area should examine the effects of additional properties unique to the body-device interface. acknowledgements the authors would like to thank those who reviewed and supported the development of this work. declaration of conflicting interests the authors declare that they have no competing interests. author contribution megan hamilton: contributed to the study concept and design, data gathering, analysis and interpretation, and contributed to the drafting of the manuscript. harry sivasambu: contributed to data analysis and interpretation, drafting of the manuscript, and read and approved the final manuscript. kamran behdinan: contributed to the study concept and design, contributed to the drafting of the manuscript, and read and approved the final manuscript. jan andrysek: contributed to the study concept and design, analyzed and 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restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.35996 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 stakeholder perspectives an operational perspective of the changing prosthetics & orthotics landscape brandt jm.* ability prosthetics & orthotics, 660 west lincoln highway, exton, pa 19341, usa. introduction the landscape of the prosthetic and orthotic (p&o) profession has changed dramatically over the past twenty years, along with the rest of the healthcare sector. for private p&o practices, these changes have represented advancements, challenges, and opportunities. navigating these changes while continuously striding to provide the highest level of p&o intervention and patient care has required innovative thinking and adopting new perspectives. as a clinician and the founder of a private p&o practice, i have had the opportunity to lead an organization throughout this changing landscape. this has provided me unique experiences, which can inform the p&o profession about the future growth of the private practice sector and further advancement of the standard of care. entry into the profession and influences toward a p&o practice model in 1993, as a junior at the pennsylvania state university (psu), i first volunteered in a regional p&o department to ‘see what the field was all about.’ to my good fortune, i shadowed a certified prosthetist orthotist (cpo), who happened to be one of the american board for certification’s (abc) early certifies who also possessed an undergraduate degree, though not required at the time. the profession was in the midst of rapidly changing entry level educational requirements for p&o certificate programs. my early mentor impressed upon me a need to sanctify the clinical care we provide as professionals by requiring advanced education, contributing to building research evidence, and measuring clinical outcomes to both quantify the benefit our p&o interventions provide to our patients in order to demonstrate the value of the care we provide. upon graduating from psu in 1995 with a bachelor of science in psychology, i enrolled in a technical program for p&o fabrication, to further my knowledge and experience in open access volume 4, issue 2, article no.19. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract leading the growth of a private prosthetic and orthotic (p&o) practice, as clinician and founder, i developed a unique perspective of this rapidly changing profession. many positive influences from my early career shaped my vison toward an innovative practice model, as well as the need to elevate the standard of care through education and the use of outcome measures. as the practice model expanded, advancements were made in electronic health records (ehr), best-in-class outsource fabrication, and clinical research. to better support clinicians and patients served, an organizational structure with an executive team was built. the practice model achieved operational efficiency through documenting best practices, developing a hiring and onboarding process, and establishing key performance indicators aligned with quality clinical care. as a regional clinical care organization, the practice model seized an opportunity to reach more patients through a partnership that brought the optimal strategic and cultural fit. bringing our innovative p&o practice model together with expertise in lean facility design, scanning, fabrication, sensor technology, product development and clinical care experience from around the world, we can advance care standards and improve the patient experience in exciting new ways. citation brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 keywords prosthetics, orthotics, outcome measures, care delivery model, automation, evidence based care, best practices, reimbursement, health economic special issue: health economics in prosthetics & orthotics * corresponding author jeffrey m. brandt, cpo ability prosthetics & orthotics, 660 west lincoln highway, exton, pa 19341, usa. e-mail: jeff.brandt@abilitypo.com orcid id: https://orcid.org/0000-0002-7377-9516 https://doi.org/10.33137/cpoj.v4i2.35996 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.35996 mailto:jeff.brandt@abilitypo.com https://orcid.org/0000-0002-7377-9516 2 brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 issn: 2561-987x an operational perspective of the changing p&o landscape brandt jm., 2021 cpoj special s p e c ia l i s s u e the profession and ultimately pursue a career as an abc certified practitioner. what felt like a brief phase back then, my time training and working as a technician provided me with valuable insights into the role fabrication played in the p&o practice model at the time and informed my perspective on opportunities for innovative care models for the future. in 2000, i graduated from the northwestern university prosthetic & orthotic center with certificates in prosthetics and orthotics. i then embarked on residencies at the rehabilitation institute of chicago (now shirley ryan ability lab) and ai dupont children’s hospital in delaware. in residency, i continued to develop my clinical skillsets in evaluation and measurement, as well as advance my clinical judgment around treatment decisions and component recommendation. as a newly minted practitioner, proper documentation and justification of my services remained a challenge. at that time, the p&o profession looked for ways to make more evidence-based decisions. i recall reading an influential article at that time entitled, ‘facing the future of orthotics and prosthetics proactively: theory and practice of outcomes measures as a method for determining quality of services’, by andrian pollack, phd, mipem and stefan moser, cpo, cped.1 this article captured the sentiment of the landscape and future direction of the p&o profession in 1997, twenty-four years ago. the authors described the need for the profession to implement routine documentation of objective outcome measures to quantify the quality and evaluate the cost-effectiveness to secure the future success of the p&o profession. little did i know at that time that the message from these authors would serve to guide decisions i would make almost two decades later. expanding a new p&o practice model through growth and research in 2004, i founded ability prosthetics & orthotics with a guiding mission of 1) providing patients with the most appropriate, affordable, and technologically advanced devices, 2) educating health care professionals, patients and payers on the latest innovations in p&o and 3) being held to the highest ethical and moral principles in accordance with corporate compliance and quality assurance plans. the practice was built upon some unique propositions for patients and payer sources that include a lean patient care delivery model focused on utilizing an electronic health records system (ehr), routinely measuring patient outcomes, utilizing best-in-class outsourced manufacturing, and conducting clinical research. with these practice attributes in place, i intended to move the profession from a very ‘device-centric’ focus to a more ‘patient-centric’ experience focus, with emphasis on consistent and repeatable care processes that producing measurable and meaningful changes in patients’ functional performances. it was my vision to pursue advancing ability’s mission through organic growth. by late 2007, ability had successfully opened four p&o facilities. this gained the attention of an article titled, conceive-ability: a new model for an old practice,2 which highlighted the ergonomically designed offices to account for the needs of the patient population, as well as practitioner and staff clinical workflow instead of fabrication processes. it was paramount to the practice model that the physical layout and build-out of the facilities be consistent across locations. this agile facility design concept and standardized workflow processes allowed rapid adoption of emerging technologies across the organization. much like a contract research organization (cro) would function for a pharma company, we could offer the same value adds for manufacturer and academic research by facilitating access to patient populations.3 this same uniformity in physical and operational design and consistency attracted opportunities to conduct clinical research. ability started conducting clinical research through sub-awards to government funded research grants with universities and technology developers. by 2010, ability was a self-proclaimed ‘super user’ of our ehr. the operational consistency and efficiency allowed ability to expand to five practice locations, with plans for a sixth. the practice model continued leveraging outsourced manufacturing with growing success. however, one limitation to the practice model was variability and nonstandard approaches through which payers requested ‘letters of medical necessity’ (lmn) and additional justification for the recommended components. by this point, the gap separating p&o technology advancements and the willingness or ability for third party payers to provide reimbursement for these interventions had grown into a wide chasm. in response, ability began to develop and submit extensive treatment plans to insurance companies on behalf of the patient to educate the payers and secure authorization. the treatment plans included thorough patient history and evaluation, baseline outcome measures, often the results of trial fittings comparing function of two potential components, images, video, and physical/occupational therapy plans. additionally, the treatment plans included citations to the latest research publications, which rooted the treatment plans in evidence. the treatment plans were reviewed and countersigned by the referring physician, therapist and often a case manager. ability also started routinely visiting and meeting with third party payers as frequently as possible. the intention of these meetings was not only to share new technology and treatment protocols. moreover, these meetings served to keep payers informed of changes within the profession, such as the changing educational requirements that were leading to master’s degrees for all p&o educational programs by 2012.4 https://doi.org/10.33137/cpoj.v4i2.35996 3 brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 issn: 2561-987x an operational perspective of the changing p&o landscape brandt jm., 2021 cpoj special s p e c ia l i s s u e while the educational requirements and research evidence in p&o were advancing, the landscape changed again as the department of health & human services’ office of inspector general (oig) released a scathing but refuted report in 2011 entitled questionable billing by suppliers of lower-limb prostheses.5 this precipitated at least a decade long trend towards various audits, lengthy appeal processes as well as severely limited l-code assignments for new p&o products. the 2011 oig report and subsequent negative pressure caused ability and others to redouble efforts to elevate the p&o profession. in response to demands for improved justification, ability launched its first formal outcome measure protocol to begin collecting objective patient-centric data to inform treatment recommendations and the component selection process. outcome measures allowed ability to document patients’ capacities and limitations, improving defense against denied claims and audits. simultaneously, the outcome measure results advanced the clinical judgement of ability clinicians through interpretation of patient outcome measures and comparison against normative population data. for example, ability began by administering the amputee mobility predictor (ampro™ and ampnopro™),6 the prosthesis evaluation questionnaire – mobility subscale (peq-ms) and the socket comfort scale (scs) for patients receiving lower limb prostheses (figure1); the timed-up-and-go (tug)7 and activities specific balance confidence scale (abc)8 for patients receiving lower limb orthoses (figure 2); and the disabilities of the arm shoulder and hand (dash) and patient specific functional scale (psfs) to patients receiving upper limb prostheses ability’s outcomes & research director was committed to consistent administration of the outcome measure protocols and also analyzing the data in meaningful ways to benefit both the patient and practitioner. ability’s thought leadership around outcome measures gained attention within the profession and was captured in an editorial article from 2014 titled, measuring the usefulness of outcome measures.9 the article detailed the approach of using objective outcome measures, documented through outcome reports, to inform important clinical decisions, such as assigning a medicare functional classification level (mfcl) (figure 3). later on, the data across the entire practice could be queried to evaluate trends across large patient populations to verify the validity and utility of the outcome measure protocols and to gain knowledge about clinical practice not otherwise possible. a digital platform and automated outcome measure report generator was developed to streamline process of collection, interpretation, and sharing of patient outcome measure results with healthcare partners. digital platforms provide the flexibility of allowing results to be presented in different formats (raw data, tables, graphs) depending on the use and audience for the information. ability includes data visualization and automated score interpretation logic in our digital solution. data aggregation is done on an as-needed basis. this work led to a peerreviewed journal publication of a retrospective chart review study, a ‘first’ for ability’s blossoming clinical research program.10 the results from that publication supported that both the amp and the peq-ms showed promise for assigning mfcl by stratifying patients’ capacity and self every amputee has concerns about receiving the right prosthesis. that’s why we’re pleased to announce ability’s new outcomes-based practice protocol. in the past, prosthetic design was based upon subjective opinions of both the patient and the practitioner. this process was prone to errors, as well as to negative patient outcomes. prosthetic technology was often overor under-prescribed, leading to amputees receiving sub-optimal devices. by taking a new approach to prosthetics evaluation, focused on outcomes-based measures, ability can now objectively determine which prosthetic components are ideal for each amputee initially, as well as over time. ability has adopted an objective outcomes-based protocol for every amputee prosthetic evaluation. ❖ amputee mobility predictor (amp) – a series of tasks measures patient potential to ambulate with a prosthesis ❖ stepwatch ankle bracelet – this “heart rate monitor equivalent for prosthetics is worn by the patient as it collects data to objectively determine function level ❖ prosthesis evaluation questionnaire – continually evaluates function and value of prosthesis ability is the first prosthetics practice to standardize the application of concurrent use of these measures across its many, mutli-region patient care offices. using an outcomes-based prosthetics practice model ensures: ❖ accurate, objective and consistent clinical prosthetic evaluations ❖ an optimal prosthetic device matched for fit and function ❖ provider accountability and validity ❖ patient satisfaction with prosthesis ❖ improved efficiencies: costs, time, materials, resources use of outcomes-based protocols advances prosthetics practice from “art-form” to “state-ofthe-art.” the need the process the solution 100% of ability’s prosthetists are trained in outcomes measures by the american academy of orthotists & prosthetists a new approach to prosthetics evaluation and ongoing care figure1: ability’s lower limb prosthetics (llp) outcome measure protocol. https://doi.org/10.33137/cpoj.v4i2.35996 4 brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 issn: 2561-987x an operational perspective of the changing p&o landscape brandt jm., 2021 cpoj special s p e c ia l i s s u e rated mobility. impactful publications, such as this, resulted in more widespread adoption of outcome measures throughout the profession. this development of ability’s practice model coincided with a concerted progress within the p&o profession toward evidence-based care (ebc). subjective assessments and ad-hoc or unvalidated evaluation forms designed to satisfy supplier requirements, such as the pavet,11 were replaced with objective, valid, and reliable instruments. this new data source posed an opportunity to evaluate the patient experience and examine the benefit of various products and technology in a real-world clinical setting, as opposed to testing with small sample sizes conducted in manufacture or institutional labs. ability soon sought opportunities to conduct institutional review board (irb) approved comparative effectiveness research protocols to evaluate new p&o products. by 2015, the profession would be faced with perhaps one of its toughest challenges yet, a proposed draft by health and human services (hhs) for a new local coverage determination (lcd) policy regarding requirements for medicare beneficiaries to qualify for prosthesis coverage.12 among others, a change to the definitions of the mfcl klevels within the lcd policy posed the gravest threat to patient access to prosthetic technology. ability’s nearly two years of amputee outcome data provided quantifiable evidence of the detrimental effects of the draft lcd, and a report was submitted by ability during an open comment period to protest the proposed changes. after nearly three months of petitioning the changes, the profession was able to reverse the proposed draft lcd and hhs agreed to assemble an interagency workgroup to further assess the need for refined medical necessity policy and the current state of evidence in the profession.13 this moment represented a turning point within the company culture at ability, as practitioners had a ‘front row seat’ in experiencing the value of objective patient clinical outcome data and the ultimate potential impact on healthcare policy. ability’s role in reversing the draft lcd and protecting patient access to the prosthetic technology energized its practitioners and staff to recommit their efforts to diligently collect outcome measures and demonstrate how p&o interventions improve patients’ functional performance. every patient has concerns about receiving the appropriate orthosis. that’s why we are pleased to announce ability’s new outcomes-based practice protocol in orthotics. in the past, orthotic design was based upon subjective opinions of both the patient and the practitioner. this process often times left the patient with an orthosis that either over or under-braced their condition, leaving them unable to reach their highest potential and creating negative patient outcomes. by taking a new approach to orthotic evaluation, focused on outcomes measures, ability can now, objectively, determine which orthotic design characteristics are ideal for each patient initially, as well as over time. ability has adopted an objective outcomes-based protocol for any lower-extremity orthotic evaluation. ❖ the timed-up-and-go (tug) is a valid measure of patient mobility, balance, walking ability and fall risk based on the amount of time required to complete the test. ❖ the activity specific balance confidence scale (abc) is a validated patient self-report measure of balance confidence in performing several everyday activities. ❖ g-walk sensor allows the practitioner to track and analyze gait deviation before and after receiving an orthosis to help determine the most appropriate intervention and to validate improvements in their gait cycle. ability is the first orthotics practice to standardize the application and concurrent use of these measures across its many, multi-region patient care offices. using an outcomes-based orthotics practice model ensures: ❖ accurate, objective and consistent clinical orthotic evaluations ❖ an optimal orthosis matched for fit and function ❖ provider accountability and validity ❖ patient satisfaction with orthosis ❖ improved efficiencies: costs, time, materials, resources use of outcomes-based protocols advances orthotics practice from “art-form” to “state-of-the-art.” the need the process the solution 100% of ability’s orthotists are trained in outcomes measures by the american academy of orthotists & prosthetists a new approach to lower limb orthotics evaluation and ongoing care figure 2: ability’s lower limb orthotics (llo) outcome measure protocol with a sample pre and post outcome measure. average tug pre and post orthotics: jon doe average abc pre and post orthotics: jon doe fall risk cut-off fall risk cut-off abc score second tug-pre 1.jan.0000 tug-post 1.may.0000 abc-pre 1.jan.0000 abc-post 1.may.0000 22 13 46 59 https://doi.org/10.33137/cpoj.v4i2.35996 5 brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 issn: 2561-987x an operational perspective of the changing p&o landscape brandt jm., 2021 cpoj special s p e c ia l i s s u e outcome report current overall ability patient satisfaction rating 95% office: exton, pa timeframe: march – april 2013 patient referred to ability p&o: jon doe (0/0/0000) consultation till prosthetic delivery: 5 weeks revision surgeries: 0 readmissions: 0 amputee mobility predictor (amp): a series of tasks measures patient potential to ambulate with a prosthesis patient assessment validation evaluation test (pavet): adls, functional requirements, physical capabilities, special considerations pavet recommendation rationalization 47 mpk stance indicated a pavet™ score between 40 and 49 would indicate a median score for adls, function, and prosthetic reliance. this score would suggest the patient requires a higher activity level to accomplish adls and also displays the ability to perform the required functions. typically a score between 40-49 will indicate the patient requires the microprocessor knee to provide maximum stability and security to enable the patient to accomplish activities of daily living (adls). ampnopro score patients (jon ampnopro score jon doe patient k3-a patient k3-b patient k3-c patient k3-d patient k3-e patient k3-f patient k3-g figure 3: example of ability’s ‘early years’ individual patient outcome measure reports, with summary of delivery timeline and revisions/readmissions, ampnopro results presented in graphic form with seven other k3 (randomized, anonymous) patients for comparison, pavet score interpretation, and overall satisfaction survey rating, based on an in-house standardized, satisfaction survey. https://doi.org/10.33137/cpoj.v4i2.35996 6 brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 issn: 2561-987x an operational perspective of the changing p&o landscape brandt jm., 2021 cpoj special s p e c ia l i s s u e while most in the p&o profession were reeling from the recent existential threats from reimbursement policy and aggressive auditing practices, ability recognized the need to expand its clinical research capabilities to address the increasing demand for research evidence. with twelve p&o facility locations by this time, ability had a reliable access to a large patient population for research recruitment. additionally, the consistent workflow operations across the organization began to attract interest in developing partnerships to conduct clinical research. ability developed formal research collaborations with universities, medical practices, and technology developers to seek and secure funding to make clinical trial opportunities available throughout its practice footprint. ability’s practitioners and patients both appreciated clinical research opportunities as a ‘value add’ that further differentiated the ability practice model within the p&o landscape.14 one example of the research conducted at ability is a clinical trial that evaluated patient-reported and performance-based outcome measures in transtibial amputees with a novel microprocessor-controlled ankle component.15 the study was sponsored by the manufacturer, freedom innovations, and represents one of the largest investigations of that technology class to-date. the study results were accepted for publication in a peerreviewed journal, and the presentation at a national conference earned the thranhardt best paper award award.16 this success demonstrated that clinical research posed an opportunity for ability and the p&o profession to contribute to research evidence at the highest level. establishing best practices & achieving operational efficiency by 2017, the practice model had matured, and ability was a strong regional patient care provider and healthcare company. navigating the p&o environment and healthcare landscape was not done without challenge. ability expanded office locations at times and closed or sold locations at other times. ability had acquired a p&o practice and integrated it into the practice model. the organization endured several cashflow crunches, outlasted the 2008 economic recession, reacted to countless medicare policy changes and continues to innovate in the face of the global covid-19 pandemic. through this phase, ability continued to make significant steps to build the executive management team to include a full c-suite (i.e chief operating officer, chief financial officer, chief information officer, and chief compliance officer), along with clinical regional directors and a clinical outcomes & research director. the onboarding process was refined to better prepare new hires to excel in the practice model. the residency program was expanded, as ability was now attracting residents and board-eligible clinicians with master’s level degrees. a management scorecard was developed to include both clinical and financial key performance indicators (kpis) to more closely align patient, practitioner and management on the shared goal of advancing patient care. this investment in organizational and management structure was necessary to support the financial success of an expanding practice model and to provide a dimension of visibility and accountability that ability’s patient care facilities and practitioners were supported in fulfilling the company’s mission. the company invested in and led a branding refresh to update the image of the organization. ability assembled a patient advocacy council (pac) from the patients it serves to provide guidance and raise awareness of key patient issues, concerns, and opportunities for the organization. practitioners and the pac collaborated in evaluating the patient journey and the care processes that contribute the greatest value to the patient experience. furthermore, it’s been my experience that our profession could also benefit from a similar and evidence-based professional approach to ‘onboarding’ new and existing staff by focusing on communication skills in p&o.17 these steps in the process were memorialized as ability’s ‘patient care pathway’. clinical best practice (bp) procedures and training manuals were developed to expand upon and provide actionable guidance for each step in the patient care pathway. the best practice manual was implemented in the onboarding process and referenced by experienced practitioners to support repeatable delivery of the most vital patient care processes. this activity and the resulting patient care pathway and best practice manual were vital in capturing the shared clinical experience and ‘tribal knowledge’ of the organization in a tangible and useful form. it’s been my personal experience, practices historically onboard practitioners with ‘tribal knowledge’, rather than taking a more formal, repeatable approach. by the beginning of 2018 and still today, the organization had made significant progress internally through documenting best practices and continuously improving clinical processes; including our ability to collect, interrupt and report patient data as illustrated with our most recent outcome report. ability was on solid financial ground, but any p&o practice could always stand to improve the balance sheet. by this time, i had transitioned away from much of the ‘day to day’ operations of the organization and was focusing more on business development initiatives, ‘culture mining’, and coaching others within the organization. ability reached a certain operational maturity across the organization for the first time with the executive management team fully in place. timing was good to explore how ability might extend the practice model to reach more patients. exploring opportunities with a partner on a larger scale emerged as a potential approach to future growth. https://doi.org/10.33137/cpoj.v4i2.35996 7 brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 issn: 2561-987x an operational perspective of the changing p&o landscape brandt jm., 2021 cpoj special s p e c ia l i s s u e around this time, i also had the opportunity to serve on the american orthotic & prosthetic association’s (aopa)18 board as well as on an executive panel for the national limb loss & preservation registry.19 these roles provided me with a new perspective from the ten-thousand-foot view of the entire p&o profession and also from a glimpse of how the rest of the healthcare sector views the p&o profession. these unique experiences influenced my beliefs about the role and impact that ability could have in re-defining the care delivery model and advancing the standard of patient care. it became apparent that to achieve the full potential of the practice model and to reach the goals the organization set out to achieve, ability would be best served by collaborating with like-minded p&o practices in a nationwide us network with a strategic partner. such a partnership could allow a collective response to external forces within and external to the p&o profession and a concentration of resources and expertise that individual organizations would not otherwise be able to harness. finding a strategic partner so how does one go about finding a strategic growth partner? ability’s board of directors recommended following a simple principle: look for strategy, financial and cultural alignment that will help identify a solid foundation from which to pursue growth in a true partnership. i believed that the most likely option for alignment on culture and mission, with the best opportunities for accelerated and sustainable growth, was a strategic partnership with an organization within the p&o industry. while the allure of private equity (pe) backed funding can be exciting, i don’t believe the p&o profession can provide the expansion expectations and sought-after return on investment in a short enough timeline to satisfy the goals of pe groups. other hybrid style lenders do exist, who could entertain moderate growth plans. however, those financial lending services require more debt. partnering with an organization within the p&o industry matched the recommendation from ability’s board of directors best. ability had been approached by and had several meetings with other large p&o practices over the recent years. we had opportunities to become a part of a larger p&o practice organization, but that alternative always seemed to stifle the organizations entrepreneurial spirit and limit the influence of ability’s unique practice model. when manufacturers within the p&o industry began to show a definitive interest in strategic partnerships with direct patient care practices in the us, it became very clear how a strategic partnership with a manufacturer presented several synergies. ability could continue the thoughtful growth trajectory that the organization has enjoyed. ability’s best-in-class clinical practice platform could assist in launching a venture into patient care, and the clinical research and outcome measure competencies of the organization could be additive to improving the products and services available to the p&o profession and patients it serves. in early 2020, ability consummated an investment from the world’s largest prosthetics manufacturer, ottobock healthcare. ability became a cornerstone in the newly formed business unit, ottobock patient care. together, we can now advance patient care standards in the us by first working to strengthen our practitioners use of evidence to make evidence-based and data-informed clinical decisions regarding treatment plan and component recommendation. we can leverage ottobock’s vast experience in p&o patient care around the world, product technologies, clinical research and reimbursement experience, growing amputee data lakes and existing best practices in the areas of lean facility design, scanning and fabrication, as well as quality assurance. we can accelerate data capture through realtime sensors and further automatic current processes, thereby bringing meaningful translation of the data; to bring those ‘daily practice’ efficiency gains to the practitioner, saving them time and providing a more individualized experience to the patient. (figure 4) figure 4: real real-time sensors to aid in data capture, developed specifically for orthotics and prosthetics are used at ability as part of daily clinical practice. a: ottobock bionic pro; b:modustm stepwatch; c: real-time, untethered gait analysis being carried out using the bionic pro and stepwatch. persons in image have given informed consent to publication. call to action as p&o patient care providers, we must learn how to maximize digital options, including automation and artificial intelligence to create local clinic practitioner efficiencies. we must have access to meaningful and actionable data that supports risk-adjusted, evidence-based treatments and quality improvement that will be paramount in providing a b c https://doi.org/10.33137/cpoj.v4i2.35996 8 brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 issn: 2561-987x an operational perspective of the changing p&o landscape brandt jm., 2021 cpoj special s p e c ia l i s s u e individually optimized patient carewhich in itself further defines our value proposition to patients and payers alike in which to continue to advance the profession. i would call for more manufacturer sponsored, irbapproved clinical research during product development cycles. we should also use the translation of the data we collect to spur additional research as well as to inform governmental and commercial payer p&o policy changes. i would call for changes in the mspo curriculums to include the teachings of health system science.20 this will better prepare the clinical leaders of tomorrow to become better interrupters with meaningful patient data to inform their patients, payers and healthcare team members. this will also help to develop the clinical leaders we’ll need in an evolving healthcare delivery system.21 we will need to demonstrate and publish frequent progress on the above-mentioned fronts to further advance comprehensive p&o legislation that sanctifies what we do as clinical care providersnot as device-centric and off-theshelf brace suppliers. that will allow us to use this progress to help define a collaborative scope with medicare around competitively bid commodity products vs. the value of evidence based clinical care. we should consider transitioning p&o practitioners to the healthcare provider status in medicare’s eyes with prescribing capabilities. a big challenge will be to continue to update the l-code reimbursement system to assimilate newer technologies at an equitable reimbursement rate in a timelier manner. we should advance concepts that support the transition to a fee-for-value (ffv) reimbursement structure and work to adapt, support and inform pdac verification changes that actively affect our profession. acknowledgements i would like to thank all former and current ability staff as well as the executive team for their commitment and contributions to advancing this vision for patient care. i would additionally like to acknowledge the ongoing leadership and support of brian kaluf cp, faaop, ability’s clinical outcome & research director, for his dedication and commitment to excellence in the pursuit of objective and actionable patient outcome measure data. declaration of conflicting interests the author is the founder, employee and a shareholder of ability prosthetics and orthotics, inc. the author is an employee and shareholder of ottobock patient care. the author is a business advisor and a shareholder of impulse technology, llc. sources of support industry funding was provided by freedom innovations to carry out a clinical trial that evaluated patient-reported and performancebased outcome measures in transtibial amputees referred to in this paper. references 1.polliack aa, moser s. facing the future of orthotics and prosthetics proactively: theory and practice of outcomes measures as a method for determining quality of services. j prosthet orthot. 1997;9(3):127-34. 2.henry k. conceive-ability: a new model for an old practice [internet]. the o&p edge. 2007; [cited 2021 january 21]. available from: https://opedge.com/articles/viewarticle/2007-0301/2007-03_04 3.herman j. cro selection 101-how to get started [internet]. clinical leader, 2018; [cited 2021 january 21]. available from: https://www.clinicalleader.com/doc/cro-selection-how-to-getstarted-0001 4.history of prosthetics & orthotics education [internet]. georgia tech. [cited 2021 january 21]. available from: https://mspo.gatech.edu/history-education/ 5.levinson d. questionable billing by suppliers of lower limb prostheses [internet]. department of health & human services office of inspector general. 2011; [cited 2021 january 21]. available from: https://oig.hhs.gov/oei/reports/oei-02-1000170.asp 6.gailey rs, roach ke, applegate eb, cho b, cunniffe b, licht s, et al. the amputee mobility predictor: an instrument to assess determinants of the lower-limb amputee's ability to ambulate. arch phys med rehabil. 2002;.613-27. doi: 10.1053/ampr.2002.32309 7. podsiadlo d, richardson s. the timed up & go: a test of basic functional mobility for frail elderly persons. j am geriatr soc. 1991;39:142-148. doi: 10.1111/j.1532-5415.1991.tb01616.x 8.powell le, myers am. the activities-specific balance confidence (abc) scale. j gerontol a biol sci med sci. 1995;50a(1):m28-34. doi: 10.1093/gerona/50a.1.m28. 9.hochnadel l. measuring the usefulness and importance of outcome measures [internet]. the o&p edge. 2014; [cited 2021 january 21]. available from: https://opedge.com/articles/viewarticle/2014-02-23/2014-03_04 10.kaluf b. evaluation of mobility in persons with limb loss using the amputee mobility predictor and the prosthesis evaluation questionnaire–mobility subscale: a six-month retrospective chart review. j prosthet orthot. 2014. 26(2): 70-76. doi: 10.1097/jpo. 0000000000000020 11.patient assessment validation evaluation test [internet]. hanger orthopedic group, inc., 2004; [cited 2021 january 21]. available from: http://www.linkia.com/documents/pavet%20protocol.pdf 12.draft lower limb prostheses lcd (dl33787) [internet]. centers for medicare & medicaid services (cms.gov), 2018; [cited 2021 january 21]. available from: https://localcoverage.cms.gov/mcd_archive/view/lcd.aspx?lcdinfo =36264%3a11 13.thomas p. draft prosthetic lcd will not be finalized! more work required to arrive at appropriate medicare coverage policy [internet]. association for the advancement of orthotics and prosthetics: washington, d.c., 2017; [cited 2021 january 21]. available from: https://naaop.us/2015/11/04/draft-prosthetic-lcdwill-not-be-finalized-more-work-required-to-arrive-at-appropriatemedicare-coverage-policy/ https://doi.org/10.33137/cpoj.v4i2.35996 https://opedge.com/articles/viewarticle/2007-03-01/2007-03_04 https://opedge.com/articles/viewarticle/2007-03-01/2007-03_04 https://www.clinicalleader.com/doc/cro-selection-how-to-get-started-0001 https://www.clinicalleader.com/doc/cro-selection-how-to-get-started-0001 https://mspo.gatech.edu/history-education/ https://oig.hhs.gov/oei/reports/oei-02-10-00170.asp https://oig.hhs.gov/oei/reports/oei-02-10-00170.asp https://opedge.com/articles/viewarticle/2014-02-23/2014-03_04 http://www.linkia.com/documents/pavet%20protocol.pdf https://localcoverage.cms.gov/mcd_archive/view/lcd.aspx?lcdinfo=36264%3a11 https://localcoverage.cms.gov/mcd_archive/view/lcd.aspx?lcdinfo=36264%3a11 https://naaop.us/2015/11/04/draft-prosthetic-lcd-will-not-be-finalized-more-work-required-to-arrive-at-appropriate-medicare-coverage-policy/ https://naaop.us/2015/11/04/draft-prosthetic-lcd-will-not-be-finalized-more-work-required-to-arrive-at-appropriate-medicare-coverage-policy/ https://naaop.us/2015/11/04/draft-prosthetic-lcd-will-not-be-finalized-more-work-required-to-arrive-at-appropriate-medicare-coverage-policy/ 9 brandt jm. an operational perspective of the changing prosthetics & orthotics landscape. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.19. https://doi.org/10.33137/cpoj.v4i2.35996 issn: 2561-987x an operational perspective of the changing p&o landscape brandt jm., 2021 cpoj special s p e c ia l i s s u e 14.prosthetic and orthotic clinical excellence [internet]. ability prosthetics & orthotics. [cited 2021 january 21]. available from: www.abilitypo.com/our-story/clinical-research-and-academics/ 15.kaluf b, duncan a, bridges w. comparative effectiveness of microprocessor-controlled and carbon-fiber energy-storing-andreturning prosthetic feet in persons with unilateral transtibial amputation: patient-reported outcome measures. j prosthet orthot. 2020. 32(4): 214-221. doi: 10.1097/jpo.0000000000000288 16.awards [internet]. the american orthotic & prosthetic association, [cited 2021 january 21]. available from: https://www.aopanet.org/about-aopa/awards/.awards 17.van netten jj, jarl g, postema k, williams ae. a toolkit for prosthetists and orthotists to facilitate progress in professional communication over the next 50 years. prosthet orthot int . 2020; 44(6): 408-415. doi: 10.1177/0309364620962325 18.board of directors [internet]. american orthotic & prosthetic association, [cited 2021 january 21]. available from: https://www.aopanet.org/about-aopa/aopa-leadership/ 19.panel member [internet]. limb loss and preservation registry, [cited 2021 january 21]. available from: https://www.llpregistry.org/panel-members 20.skochelak se, hammoud mm, lomis kd, borkan jm, gonzalo jd, lawson le, et al., eds. health systems science, 2nd ed. philadelphia, pa: elsevier; 2020 21.the critical role of clinical leaders: transforming care today and tomorrow [internet]. nejm catalyst. [cited 2021 january 21]. available from: https://www.scribd.com/document/374050383/thecritical-role-of-clinical-leaders-transforming-care-today-andtomorrow author scientific biography jeffrey m. brandt, cpo, chairman & founder, ability prosthetics & orthotics; director, business development, ottobock patient care. jeffrey m. brandt, founded ability prosthetics and orthotics, an evidence-based p&o practice that has grown to twelve offices across three states. since its inception in 2004, ability has led the advancement and implementation of outcome measures in daily practice, founded lifenhanced magazine, and assembled a patient advisory council to inform of patient-centric best practices. through brandt’s leadership, ability has prioritized a focus on patient care, outcomes data, delivery of care, business analytics, community based adaptive programs and comparative effectiveness product research and development. in addition to founding ability, brandt is a co-founder of kinetic revolutions of which the most notable product is the height adjustable pylon for use on prosthetic limbs. after graduating from penn state university in 1995, brandt completed the prosthetics technician program at spokane falls community college in spokane, washington and became an abc certified technician. he then attended northwestern university’s feinberg school of medicine’s prosthetic & orthotic program in 1999. he subsequently completed his orthotic residency at the rehabilitation institute of chicago and his prosthetic residency at lawall p&o in delaware, where he serviced a.i. dupont children’s hospital. as a student, brandt was awarded the gunther gehl prosthetics scholarship by the midwest chapter of the american academy of orthotists and prosthetists (aaop) and has been named to the o&p news 175. brandt currently serves on the american orthotic & prosthetic association’s (aopa) board, limb loss & preservation registry external collaborative panel (ecp) and as a business advisor to impulse technology. https://doi.org/10.33137/cpoj.v4i2.35996 http://www.abilitypo.com/our-story/clinical-research-and-academics/ https://www.aopanet.org/about-aopa/awards/.awards https://www.aopanet.org/about-aopa/aopa-leadership/ https://www.llpregistry.org/panel-members https://www.scribd.com/document/374050383/the-critical-role-of-clinical-leaders-transforming-care-today-and-tomorrow https://www.scribd.com/document/374050383/the-critical-role-of-clinical-leaders-transforming-care-today-and-tomorrow https://www.scribd.com/document/374050383/the-critical-role-of-clinical-leaders-transforming-care-today-and-tomorrow all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 2 2022 research article olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i2.37963 1 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 research article does trans-radial longitudinal compression influence myoelectric control? olsen j1*, day s2, dupan s3, nazarpour k3, dyson m1 1 intelligent sensing laboratory, school of engineering, newcastle university, uk. 2 national centre for prosthetics and orthotics, strathclyde university, uk. 3 edinburgh neuroprosthetics laboratory, school of informatics, the university of edinburgh, uk. introduction modern trans-radial limb prostheses comprise three main elements: a state-of-the-art bionic hand,1,2 sensors for capturing electromyographic (emg) signals, and a socket the design of which has not changed significantly in over 60 years.3-5 the introduction of the muenster and northwestern style sockets led to the emergence of self-suspending transradial prostheses as early as 1960s.4,6,7 these designs eliminated the need for a suspension harness,7 giving more freedom to wearers.8 around a decade later, emgcontrolled terminal devices became prevalent. the emg sensors, which are required for control, were retrofitted into self-suspending socket designs.3 since then, there has been a vast increase in the complexity of myoelectric devices available.9 despite this, trends indicate that abandonment rates have not reduced over time, with reports as high as 44% in literature.10 lack of control, poor reliability and discomfort are key causes of abandonment of myoelectric prostheses.5,11-16 traditional socket designs are not optimised to accommodate the weight of additional hardware or to prevent loss of contact between the emg sensors and their target muscle groups.3 restricted space within most sockets generally only allows for one or two clinicalstandard electrodes.17 additionally, some modern terminal devices exceed 0.6kg,18 approximately three times the open access volume 5, issue 2, article no.2. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: existing trans-radial prosthetic socket designs are not optimised to facilitate reliable myoelectric control. many socket designs pre-date the introduction of myoelectric devices. however, socket designs featuring improved biomechanical stability, notably longitudinal compression sockets, have emerged in more recent years. neither the subsequent effects, if any, of stabilising the limb on myoelectric control nor in which arrangement to apply the compression have been reported. methodology: twelve able-bodied participants completed two tasks whilst wearing a longitudinal compression socket simulator in three different configurations: 1) compressed, where the compression strut was placed on top of the muscle of interest, 2) relief, where the compression struts were placed either side of the muscle being recorded and 3) uncompressed, with no external compression. the tasks were 1) a single-channel myoelectric target tracking exercise, followed by 2), a high-intensity grasping task. the wearers’ accuracy during the tracking task, the pressure at opposing sides of the simulator during contractions and the rate at which the limb fatigued were observed. findings: no significant difference between the tracking-task accuracy scores or rate of fatigue was observed for the different compression configurations. pressure recordings from the compressed configuration showed that pressure was maintained at opposing sides of the simulator during muscle contractions. conclusion: longitudinal compression does not inhibit single-channel emg control, nor improve fatigue performance. longitudinal compression sockets have the potential to improve the reliability of multi-channel emg control due to the maintenance of pressure during muscle contractions. article info received: january 14, 2022 accepted: june 30, 2022 published: july 20, 2022 citation olsen j, day s, dupan s, nazarpour k, dyson m. does transradial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2.https://doi.org/10.33137/cpoj.v 5i2.37963 keywords amputation, prosthetic, socket, compression, myoelectric, emg, control, fatigue, compressionrelease, trans-radial, upper-limb * corresponding author jennifer olsen, intelligent sensing laboratory, school of engineering, newcastle university, uk. email: j.olsen@newcastle.ac.uk orcid id: https://orcid.org/0000-0001-9076-3092 https://doi.org/10.33137/cpoj.v5i2.37963 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i2.37963 https://doi.org/10.33137/cpoj.v5i2.37963 https://orcid.org/0000-0001-9076-3092 2 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj weight of a split-hook, a common body-powered alternative.19 adjustable electrode housings have been trialled in an attempt to assist myoelectric control with existing sockets.15 however, there are no known novel socket styles designed specifically to optimise emg control, and research into this topic is scarce.16 in contrast, several designs have emerged with the aim of improving biomechanical stability, most notably those featuring longitudinal compression.7,20-22 it is known that consistent contact between the residuum and the electrodes is required for reliable myoelectric control,3,16 but to the best of our knowledge there is currently no published research detailing whether the enhanced tissue stabilisation provided by longitudinal compression sockets improves myoelectric prosthesis reliability. out of the available longitudinal compression socket designs, the compression-release stabilized (crs) socket is a well-known design for which fitting notes are documented.20 the theory behind longitudinal compression sockets is that the compressed areas stabilise the underlying structures and reduce lost-motion, the relative motion between a socket and residuum during movement, improving biomechanical stability.20 relatively recent designs, such as the crs20 feature both longitudinal compression and cutout release regions for the displaced tissue to spill into.20,21 earlier iterations of sockets featuring localised compression such as the “trans-radial anatomically contoured (trac) interface”7 and the “anatomically contoured and controlled interface (acci)”22 did not feature release areas to allow the displaced tissue to move into, and therefore had limited success. this paper will therefore reference the crs design to explain the fundamental principles of longitudinal compression sockets. note that throughout the paper we have referred to longitudinal compression as a concept, not a specific socket design. conventional crs sockets are fitted using a protected procedure which only trained professionals can perform.20 the process involves bar-shaped depressors indenting the residuum during the casting stage to create areas of intentional localised compression.20 the location of the bars is determined by the professional conducting the crs cast, based on underlying tissue geometry and avoiding major blood vessels.20 currently there is no public guidance or published scientific evidence to suggest which sensor location in a crs socket is more beneficial for myoelectric control. in the original paper that proposed the crs design,20 the image of the socket are contradictory. the image shows the electrodes mounted on compression struts, but the text suggests that they could be placed on a membrane in the relief area. anecdotally, it is known that in sockets featuring depression bars, such as the crs, electrodes are usually mounted in compressed areas for convenience and several images of crs sockets support this.20,23 other positive effects that longitudinal compression sockets may have on residuum physiology are yet to be reported. compression garments are frequently used therapeutically for medical conditions such as oedema and cerebral palsy and to improve athletic performance.24-30 as longitudinal compression sockets provide regions of both high and low pressure, it is assumed their mechanism of action will be similar to that of “directional compression” garments, which provide targeted areas of varying compression.26 directional compression garments have been shown to reduce physiological responses which would result in muscle fatigue during sport and physical activity,27,28 however it is not yet known whether longitudinal compression sockets provide the same benefit. additionally, high pressure must be applied with caution, as excessive localised compression can result in tissue ischemia and skin breakdown.29,31 if the pressure restricts blood flow for a significant period of time, wounds, injuries and even tissue death can occur.20,31,32-34 finding an acceptable level of compression and blood perfusion is a complex task for prosthetists without additional equipment.20 no quantitative method or guidelines are available, however postischaemic hyperemia (redness after a prosthesis is removed) can be used to gauge acceptable compression levels.20 extrapolating existing data for medical devices is also complex as many studies reporting safe levels of compression for medical devices refer to stockings which provide a different mechanism of compression.33 additionally, the safe range for compression garments depend on the location compression is being applied to.29,31,32-35 similarly, studies of localised pressure often refer to pressure sores resulting from long-term tissue ischaemia in immobile patients.29,35 this study explored the potential effect of longitudinal compression on three fundamental factors central to the use of myoelectric prostheses; namely, control, electrode-skin contact and muscle fatigue. we hypothesised longitudinal compression would provide enhanced myoelectric control due to immobilisation of the target muscles. methodology the local ethics committee at the newcastle university approved this study (ref: #11532/2020 and #20-dys-050). twelve able-bodied participants between 20-40 years of age were recruited (sex: 7 male, 5 female). all participants were active individuals who self-identified as right-hand dominant. as our participant pool was limited in size, and we did not anticipate factors such as mass, height, or grip strength to be associated with myoelectric ability; only participant gender and age range were recorded. https://doi.org/10.33137/cpoj.v5i2.37963 3 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj a two-part experiment featuring a custom-made longitudinal compression simulator was performed. the first part of the experiment assessed the effect of longitudinal compression on emg control using a simple target tracking task. the second part assessed the effect of longitudinal compression on the rate of forearm fatigue during a short, high intensity grasping activity. equipment to enable longitudinal, localised forearm compression, a custom rig was developed, shown in figure 1(a). the rig had four depressor bars, simulating the struts of a longitudinal compression socket. this design was chosen as it is reported to be the most stable configuration for a crs socket,20 a common and well documented example of a longitudinal compression socket. the bars were evenly spaced around the rig. each bar contained two ohmite fsr07ce force sensing resistors (fsrs) to allow the compression applied to be calibrated and monitored. bars could be depressed and released using manually adjustable wing-nuts to fit all participants. each bar was 3d printed in two halves featuring recessed areas to house the fsrs and depressors to evenly compress the fsrs, as shown in figure 1. the inner-design of the depressor bars allowed reliable calibration of the fsrs prior to use due to the rigid material and consistent depressor area, as shown in figure 1(b). each fsr was calibrated between 0-20kpa (≈ 0-150mmhg) using calibration weights. during both calibration and the experiment, pressure data was recorded using a teensy® 4.0 board. the teensy ran firmata firmware and sampled pressure data at 1000 hz. emg sensors (delsys mini, delsys, usa) were used to acquire emg data at 2000 hz. the axopy experimental library was used to synchronize pressure and emg data, and to provide online visualisation.36 two dynamometers (camry, usa) were used during the fatigue experiment. safety given that there was no documented precedent for the appropriate level of compression to apply, it was calculated based on the task duration. chang et. al established a parabolic relationship between the length of time that tissue is compressed, magnitude of compression, and safety.32 assuming no shear forces, the relationship is valid for between 2 to 7 hours of compression. the task was predicted to take 2 hours approximately, hence the maximum safe pressure level was calculated to be 16kpa (120mmhg). to ensure safety and make the results more applicable to daily wear of a myoelectric prostheses, the target range of compression was lowered to 6.7-9.3kpa (5070mmhg), which would give an approximate allowable wear time of 3.4-4.8 hours, with a tolerance range of 5.3-10.7kpa (40-80 mmhg) per bar. it is important to note that although no numerical precedent is documented, the crs socket “compress the tissue against the long bone [...] until it no longer yields”,37 which is much higher than the levels featured in this experiment as even at the upper range of 10.7kpa, the limb were not completely compressed. during calibration a real time display provided a colour coded pressure value data from each fsr to the experimental operator to facilitate calibration. figure 1: (a): the 3d-printed compression rig; (b): a cad representation of the compression bar showing the inbuilt fsr depressors; (c): the top half of a compression bar, showing the fsr sensors inside; (d): the bottom half of a compression bar, showing the fsr depressors. a) c) b) d) https://doi.org/10.33137/cpoj.v5i2.37963 4 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj experiment three compression-release socket configurations were tested. each condition changed the location of the compression bars while an emg sensor remained fixed in an identical location on the extensor muscle group. the socket configurations tested are shown in figure 2 and were defined as follows: uncompressed: the emg sensor was affixed to the skin with no external compression. relief: the emg sensor is located in the relief area, equidistant between two compression bars. compressed: the emg sensor is located underneath a compression bar. for both the uncompressed and relief configurations, a delsys adhesive interface (adhesive film) was used to affix the emg sensor to the skin. for the compressed configuration this was not required as the compression bar held the sensor in place. control prior to each experiment a calibration process was performed wearing the simulator as shown in figure 3 (a). participants were asked to position their dominant arm at their side, with 90-degree elbow flexion and their wrist in a neutral position. participants were shown how to contract their wrist extensors using wrist motions and the extensor muscle group was manually located by palpating the arm. the emg sensor was placed on the extensor area and the quality of the acquired emg signal was confirmed by visual inspection. the location of the electrode was then marked using a marker pen. an emg calibration procedure was performed.38 holding the aforementioned neutral position, a mean absolute value (mav) was captured over a 750ms window, representative of two states: baseline emg activity (ymin), and a comfortable contraction (ymax). it was explained that participants would need to repeat this contraction many times throughout the experiment, hence they should not contract too much to prevent future discomfort. the mav of the raw emg data input was denoted as (y). normalisation constants were derived from calibration mav data, and in all consequent conditions emg was normalised using said constants. normalised muscle activity (ynorm) was calculated as: ynorm = (y − ymin)/(ymax − ymin) (1) in all experiments ynorm was used for control. each participant was calibrated in the experimental condition they performed first. for further details of the calibration procedure see the methods described in dupan et. al.38 a simple, 1-dimensional myoelectric target tracking task was used to test control. the task visuals and processing were written in python, using the axopy library.36 the task comprised dynamic on-screen targets which rise, hold and fall from the minimum emg value scaled to two target heights: 25% and 100% of the comfortable emg contraction, as shown in figure 3(b). participants were instructed to hold their arm in the position established during calibration and to track the target with the cursor. figure 2: experimental conditions tested. the approximate location of the wrist extensors and flexors are shown relative to the positions of the rig during the different data acquisition configurations and the corresponding locations of bar 1, 2, 3 and 4. “s” represents the location of the emg electrode throughout all three configurations. (a): uncompressed configuration; (b): relief configuration; (c): compressed configuration. uncompressed relief compressed forearm cross-section extensors extensors extensors flexors flexors flexors a) b) c) https://doi.org/10.33137/cpoj.v5i2.37963 5 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj the cursor was controlled by the normalised muscle activity of the extensor group, as shown in figure 3(c). each task block consisted of 20 trials 10 low targets and 10 high targets displayed in random order. each trial was the same duration, regardless of whether the target was low or high, hence the high targets moved faster than the lower targets to rise, hold and fall within the same timeframe. participants completed one familiarisation block of 20 trials, which was not included in the analysis. four blocks of 20 trials were recorded in each configuration producing a total of 240 trials per participant. each participant performed the control task in all three configurations. the testing order for the configurations was balanced between participants. data from each control trial was split into three time-periods: rise, hold, and fall, corresponding to the target motion. the absolute deviation of the normalised mav from the target was calculated for each data point, and a numerical mean calculated. participant averages were calculated to provide twelve average scores per time-period, per configuration. score distributions were checked for normality using a shapiro-wilks test. the majority of data sets were found to be non-normally distributed (p < 0.05). friedman tests were used to check for statistical differences between the three rig configurations for: 1) the rise, hold and fall section of the trial, and 2) between the low and high targets. pressure for configurations relief and compression, the pressure applied by the rig was fine-tuned manually before commencing data acquisition. the acceptable pressure range was 5.3-10.7kpa (40-80 mmhg) with the arm in the neutral position, with the ideal range being 6.7-9.3kpa (5070mmhg). during the compressed configuration, bar 1 compressed the approximate area of the extensors and bar 3 compressed the approximate area of the flexors. although both were within the target 6.7-9.3kpa (50-70mmhg) pressure range, the pressure exerted onto the extensors by bar 1 was consistently around 2kpa (15mmhg) higher than that exerted onto the flexors by bar 3. this is due to anatomical differences. the extensors are a larger muscle group than the flexors, providing more cushioning and tissue compliance. additionally, bar 1 is aligned with the belly of the extensors, whereas bar 3 is closer to the bone and above the approximate area of the flexors. the enhanced tissue cushioning and alignment of bar 1 allow a higher pressure to be achieved than bar 3. it is assumed that individuals with acquired limb differences would generally have a similar muscle structure to the able-bodied volunteers, however individuals with congenital limb differences would show more varied limb structures. regardless, the simulator was designed to be fine-tuned to figure 3: a) a photo of the compression simulator being worn. note the limb is extended more than the 90° than described in the text to obtain a clear picture. b) an example of what the task looked like on screen as presented to the participants. the white line is the moving target, and the green ball is the cursor which participants control with their emg activity. c) an example plots from a high-target task with the corresponding emg activity showing the participant tracking the height of the cursor. only the three gray areas highlighted in the graph were used to calculate participant scores, corresponding to the rise, the hold period, and fall of the on-screen target. time (seconds) target height normalised mav emg t a rg e t h e ig h t rise hold fall a) b) c) target held t a rg e t ri s in g t a rg e t fa lli n g https://doi.org/10.33137/cpoj.v5i2.37963 6 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj fit each individual’s limb, with the aim of achieving approximately equal compression provided by all four bars. the intention of this analysis was to gauge whether longitudinal compression could prevent electrode lift-off. hence, only the compressed configuration data was assessed for this section as it allows recording of both emg and pressure data directly above the emg site. the average rise and fall of pressure recorded from bar 1, the emgbearing extensor bar, and bar 3, the flexor bar, throughout all compressed trials was calculated to assess the effect of muscle contraction on emg sensor pressure within the compression simulator. data recorded during compression conditions were separated into two groups: high targets and low targets. for both groups, data points recording pressure change and emg activity were averaged to observe mean fluctuation during the trial. fatigue the effect of longitudinal compression on forearm fatigue was tested using a bi-manual task. participants’ forearm extensors were located on both arms as described in section control and an emg sensor was affixed to both forearms above the extensors. the position of the sensors was validated on screen as described in section control. the compression simulator was applied to one arm as described in the compressed configuration. participants were asked to grip two identical dynamometers, using their maximum grip strength i.e., a sustained isometric maximal contraction, for as long as they felt they could, and to release them simultaneously. this test was based on similar methodology described by klass et. al39 and gillani et. al.40 handheld dynamometers were chosen for this experiment to avoid the use of unnecessary custom hardware. testing order was balanced so that compression was applied to the dominant arm and non-dominant arm on an equal number of instances to minimise the effect of structural differences.41-44 the physiological effects of fatigue on muscles vary depending on the intensity and duration of the fatiguing task, as well as the muscle being observed.24,45 pilot experiments were conducted, and the volunteers reported feeling muscle fatigue for several hours after conducting the single maximal grip strength task. due to this, the fatigue task was only performed once per participant to avoid a multi-day experiment which may have introduced more variance between performance. the two configurations selected to be compared were uncompressed and compressed, as this allowed a direct comparison of the extensors with and without external pressure. hence, the relief configuration was eliminated for this task. for each participant’s individual pair of compressed and uncompressed emg recordings, the “active data” was analysed, i.e., the entire duration of the participant’s contraction. the length of each pair of recordings varied depending on how long the participant contracted their muscles during the fatigue task. hence, for each condition, a median frequency analysis was performed using 1 second intervals. observing changes to the median frequency of an emg recording is a well-established method of gauging muscle fatigue.46 a percentage difference was calculated for each participant, based on the difference between the first and last datapoints of the median frequency analysis. shapiro-wilks tests were used to check for normality in percentage decreases. none of the datasets were found to be non-normally distributed (p < 0.05). wilcoxon’s rank (p < 0.05) was used to check for significance between the conditions. the shapiro-wilks test and wilcoxon’s rank analysis were repeated with data split into dominant arm recordings and non-dominant arm recordings, to assess whether limb dominance influenced fatigue. results experimental results from the control task, the pressure analysis and the fatigue task are detailed in the following sections. control average scores for the rise, hold and fall period of the task are shown in figure 4(a). average scores for low target and high target trials for each condition are shown in figure 4(b). there was no significant difference between any conditions during the rise (p = 0.717), hold (p = 0.920) and fall (p = 0.717) periods. the results for the rise, hold and fall periods were similar, with a small decrease in error for the fall period. as would be expected, there was a notably higher error for the faster-moving high target trials than low target trials. however, there was no significant difference (p < 0.05) in average scores between conditions for either high (p = 0.77) or low (p = 0.368) targets. an assessment of individual participant performance revealed a weak trend r2 = 0.349 of error reduction as the trials progressed, shown in appendix a. pressure figure 5(a) shows the mean fluctuations in pressure data recorded during all trials split by high and low targets for bar 1, located above the wrist extensors, and bar 3, located approximately above the wrist flexors, and figure 5(b) shows the corresponding emg data. recordings from both the extensor bar and flexor bar showed an increase in pressure during contractions at the opposing sides of the rig for both high and low targets. due to the anatomical differences described in section pressure (methodology), the pressure recorded from bar 1, above the extensors, was consistently around 2kpa (15 mmhg) higher than the pressure recorded from bar 3, above the flexors. despite this, the fluctuation followed the same pattern for both bars in both high and low target groups. https://doi.org/10.33137/cpoj.v5i2.37963 7 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj the results of this test showed that pressure rose at opposing sides of the socket simulator during contractions. fatigue figure 6 shows a comparison of rates of fatigue for the dominant vs. non-dominant arm, and the compressed vs. uncompressed arm. there was no significant difference in the mean rate of fatigue between participants’ arms in the compressed and uncompressed conditions (p = 0.182), but the mean reduction in median frequency was marginally lower for the compressed configuration than the uncompressed. similarly, there was no significant difference between the dominant and nondominant arm rates of fatigue (p = 1). the results of this test showed that longitudinal compression applied to the forearm muscles during a high-intensity task did not produce the same figure 4: results from the myoelectric target tracking control tasks. mean absolute deviation from the target for (a) the rise, hold and fall periods for all trials (b) low targets and high targets. in all box plots, the upper and lower box boundaries represent the respective upper and lower quartiles, the whiskers represent the maximum and minimum excluding outliers, and the centre line represents the median. figure 5: the mean emg recording and corresponding pressure recordings from the extensors (shown in blue) and flexors (shown in red) from a) the low target trials and b) the high target trials, across all compressed trials from all participants. the black line represents the emg target height, and the shaded bands show the standard deviation. for the emg recordings, only the period where the target is rising, held, or falling in height is shown, as participants where not assessed outside of this period. the pressure recorded above the extensors was consistently around 2kpa (15 mmhg) higher than the pressure recorded above the flexors due to anatomical differences described in detail in section 2.2.2. uncompressed relief compressed rise hold fall rise hold fall low target high target m e a n d e v ia ti o n f ro m t a rg e t https://doi.org/10.33137/cpoj.v5i2.37963 8 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj fatigue-reducing effect observed with compression garments.28 discussion the aim of this study was to assess and quantify the effect of longitudinal compression on fundamental factors affecting emg prosthesis wearability: control, maintenance of contact between the electrodes and the skin, and fatigue. the results of this investigation indicated that moderate longitudinal compression had no significant effect on the participants closed-loop control abilities in our myoelectric target tracking task. on average, the participants showed a weak trend of improvement (r2 = 0.349) as the control task progressed, as shown in appendix a. this trend is likely to be indicative of participants learning to perform the task and will account for some of the variability within the scores. given the data presented it is unlikely that this variability influenced the results. the results from the control task indicate that when selecting a socket design featuring selective longitudinal compression, alternative factors such as fit and comfort should be prioritised over the emg control capability provided by the socket. most conventional clinical trans-radial sockets feature a rigid socket design within which emg sensors are recessed into the socket wall.3 the extensor carpi radialis and flexor carpi radialis are common muscle sites for dual-channel emg control, located approximately equidistant around the forearm. this design is susceptible to “electrode lift-off” during movements, contractions or loadbearing, the residual limb presses against one side of the socket.3,15 this can cause the opposing side to disengage with the socket wall and the electrode embedded within it, leading to a loss of contact between the electrode and skin.3,15 pressure data recordings during compressed configuration trials, as shown in figure 5, suggest that integrating electrodes into longitudinal compression bars can be used to maintain pressure at the socket-skin interface during muscle contractions. this study used a simulator as using real sockets was out of scope for the research. hence, a follow-on study utilising real sockets should be conducted. rates of forearm fatigue observed during a short burst of intense physical activity did not differ between compressed and uncompressed arm conditions, however the reduction in median frequency was marginally smaller for the compressed configuration, i.e., the limb fatigued slightly less than in the uncompressed configuration. no significant difference was observed in rates of fatigue between the dominant and non-dominant limb, making it unlikely that this balancing condition had any influence on results. it is important to note that, due to the lack of specialised equipment, this study featured a standard dynamometer and tested hand-grip strength rather than fatiguing the wrist extensors. commonly, studies assessing compression for sporting purposes are conducted over several, longer recording sessions,24,26,27,47,48 whereas this study looked at one recording of maximum muscle contraction from the participants. further research is therefore necessary to be certain about any relationship between longitudinal compression and limb fatigue. in summary, both the myoelectric control and fatigue data indicated that the properties of longitudinal compression sockets have little influence on factors relevant for emg based control of an upper-limb prosthesis while pressure data suggests longitudinal compression bars could be used to maintain electrode contact during prosthesis use. compression struts in longitudinal compression sockets are intended to displace tissue in order to reduce lost motion. further research will be necessary to determine whether it is possible to design struts which are able to displace tissue whilst also sensing the emg activity at a signal to noise ratio sufficient for prosthesis control. able-bodied participants were recruited to minimise the effect of variation in limb length and structure. this allowed a fair comparison between different compression configurations. hence, a simulator was designed to allow the inclusion of able-bodied volunteers. the literature linking compression simulators to real longitudinal compression sockets is sparse, with the only known previous example being sang, et al.49 it is assumed that the majority of acquired trans-radial amputees would have a similar muscle structure to able-bodied individuals, however they may require shorter or narrower compression bars, to suit the length and shape of their residuum. future figure 6: rates of fatigue for the dominant vs. nondominant arm, and the compressed vs. uncompressed arm. the rate of fatigue is measured as the scalar of the trendline for the median frequency analysis of emg recordings of each arm. the upper and lower box boundaries represent the respective upper and lower quartiles, the whiskers represent the maximum and minimum excluding outliers, and the centre line represents the median. https://doi.org/10.33137/cpoj.v5i2.37963 9 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj experiments should include amputees, ideally those who regularly use a myoelectric device. limitations as preliminary research in this area, this study featured a number of limitations. the socket simulator designed for this study did not allow for any form of distal loading to simulate wearing a terminal device. loading will affect many of the factors analysed in this study and will be considered in follow-on studies. additionally, the control task and pressure data were captured at 90 degrees elbow flexion only. to further understand the effect of longitudinal compression on myoelectric control, future experiments should capture a variety of arm positions. this socket simulator also featured compression bars in an equidistant design around the limb. this design allowed us to test whether localised, longitudinal compression altered emg properties for single channel control. adjustable compression bar positions will be necessary to test whether results generalise to multichannel emg and pressure-maintenance across various sensor sites. conclusion longitudinal compression in an equally distributed 4-bar socket simulator does not inhibit single-channel emg control, nor does it improve fatigue performance of the wristextensors during a high-intensity, short-duration contraction. pressure data reported in this study indicated that longitudinal compression, when applied tangential to the muscle, help maintain overall contact between the skin and the socket at opposing sides. therefore, longitudinal compression sockets may improve multi-channel emg control in a design which integrates the emg sensors into the compression struts. acknowledgements the authors would like to thank sarah winlow for her proofreading and feedback on an earlier version of the manuscript. declaration of conflicting interests the authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. author contribution jennifer olsen: writing (original draft preparation). jennifer olsen, sarah day, sigrid dupan, kianoush nazarpour, matthew dyson: conceptualization, writing (review and editing). all authors have read and agreed to the published version of the manuscript. sources of support this work was supported by the engineering and physical sciences research council (epsrc), u.k., under studentship number 2281137 from ep/n509528/1 and ep/r51309x/1 (jo). ethical approval the local ethics committee at newcastle university approved this study (ref: #11532/2020 and #20-dys-050). references 1.imran a, escobar w, barez f. design of an affordable prosthetic arm equipped with deep 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https://www.glasgowtimes.co.uk/news/18994494.glasgow-hospital-patient-becomes-first-benefit-bionic-hand/ https://scholarworks.montana.edu/xmlui/handle/1/14591 https://www.woundsinternational.com/resources/details/wound-essentials-3-problem-solving-preventing-pressure-damage https://www.woundsinternational.com/resources/details/wound-essentials-3-problem-solving-preventing-pressure-damage 11 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj 41.vanswearingen jm. measuring wrist muscle strength. j orthop sports phys ther. 1983;4(4):217-28. doi: 10.2519/jospt.1983. 4.4.217 42.decostre v, canal a, ollivier g, ledoux i, moraux a, doppler v, et al. wrist flexion and extension torques measured by highly sensitive dynamometer in healthy subjects from 5 to 80 years. bmc musculoskelet disord. 2015;16(1):1-1. doi: 10.1186/s12891-0150458-9 43.williams dm, sharma s, bilodeau m. neuromuscular fatigue of elbow flexor muscles of dominant and non-dominant arms in healthy humans. j electromyogr kinesiol. 2002;12(4):287-94. doi: 10.1016/s1050-6411(02)00024-x 44.adam a, luca cj, erim z. hand dominance and motor unit firing behavior. j. neurophysiol. 1998;80(3):1373-82. doi: 10.1152/jn. 1998.80.3.1373 45.walker s, davis l, avela j, häkkinen k. neuromuscular fatigue during dynamic maximal strength and hypertrophic resistance loadings. j electromyogr kinesiol. 2012;22(3):356-62. doi: 10.1016/j.jelekin.2011.12.009 46.allison gt, fujiwara t. the relationship between emg median frequency and low frequency band amplitude changes at different levels of muscle capacity. clin biomech. 2002;17(6):464-9. doi: 10.1016/s0268-0033(02)00033-5 47.zavala l, snyder c, becker j, seifert j. directional compression and muscle activity in a retired world cup alpine skier. isbs proceedings archive. 2017;35(1):215. 48.sperlich b, born dp, zinner c, hauser a, holmberg hc. does upper-body compression improve 3× 3-min double-poling sprint performance?. int j sports physiol perform. 2014;9(1):48-57. doi: 10.1123/ijspp.2013-0137 49.sang y, li x, luo y. characteristics of a volume-adjustable compression chamber for transradial prosthetic interface. proc inst mech eng h p i mech eng h. 2016;230(7):650-60. doi: 10.1177/0954411916645132 https://doi.org/10.33137/cpoj.v5i2.37963 12 olsen j, day s, dupan s, nazarpour k, dyson m. does trans-radial longitudinal compression influence myoelectric control? canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.2. https://doi.org/10.33137/cpoj.v5i2.37963 issn: 2561-987x longitudinal compression sockets: myoelectric control olsen et al., 2022 cpoj appendix a: all participants' mean average deviation from target over trials https://doi.org/10.33137/cpoj.v5i2.37963 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 research article escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.36744 1 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 research article exploration of vibrotactile biofeedback strategies to induce stance time asymmetries escamilla-nunez r1,2 *, sivasambu h2, andrysek j1,2 1 institute of biomedical engineering, university of toronto, toronto, canada. 2 bloorview research institute, holland bloorview kids rehabilitation hospital, toronto, canada. introduction human gait is a complex physical activity involving the primary motor and somatosensory cortices, as well as the spinal cord (i.e., central pattern generator for locomotion), and the musculoskeletal system.1-3 the interaction between the central and peripheral nervous systems, reflexes, muscles, and joints allows individuals to ambulate in a stable, synchronized, and symmetrical manner.4 gait symmetry is the degree of equality of biomechanical parameters between limbs within a gait cycle.4 able-bodied gait is typically characterized by a high degree of symmetry. however, neurological disorders or physical impairments such as parkinson’s,5 cerebral palsy,6 stroke,7 incomplete spinal cord injury,8 and lower limb amputation,9 can lead to pathological gait, resulting in atypical and asymmetrical gait patterns.2 gait asymmetry can affect diverse biomechanical and physiological open access volume 5, issue 1, article no.2. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: gait symmetry is the degree of equality of biomechanical parameters between limbs within a gait cycle. human gait is highly symmetrical; however, in the presence of pathology, gait often lacks symmetry. biofeedback (bfb) systems have demonstrated the potential to reduce gait asymmetry, improve gait function, and benefit overall long-term musculoskeletal health. objective(s): the aim of this study was to develop a bfb system and evaluate three unique bfb strategies, including bidirectional control – constant vibration (bc), bidirectional control – variable vibration (bv), and unidirectional control – variable vibration (uv) relevant to gait symmetry. the assessed feedback strategies were a combination of vibration frequency/amplitude levels, vibration thresholds, and vibrotactile stimuli from one and two vibrating motors (tactors). learning effect and short-term retention were also assessed. methodology: testing was performed using a custom bfb system that induces stance time asymmetries to modulate temporal gait symmetry. the bfb system continuously monitors specific gait events (heel-strike and toe-off) and calculates the symmetry ratio, based on the stance time of both limbs to provide real-time biomechanical information via the vibrating motors. overall walking performance of ten (n=10) able-bodied individuals (age 24.8 ± 4.4 years) was assessed via metrics of symmetry ratio, symmetry ratio error, walking speed, and motor's vibration percentages. findings: all participants utilized bfb somatosensory information to modulate their symmetry ratio. uv feedback produced a greater change in symmetry ratio, and it came closer to the targeted symmetry ratio. learning or short-term retention effects were minimal. walking speeds were reduced with feedback compared to no feedback; however, uv walking speeds were significantly faster compared to bv and bc. conclusion: the outcomes of this study provide new insights into the development and implementation of feedback strategies for gait retraining bfb systems that may ultimately benefit individuals with pathological gait. future work should assess longer-term use and long-term learning and retention effects of bfb systems in the populations of interest. article info received: june 7, 2021 accepted: october 1, 2021 published: october 29, 2021 citation escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2.https://doi.org/10.33137/cpoj. v5i1.36744 keywords gait, human movement, biofeedback, learning effect, motor control, rehabilitation, short-term retention, symmetry ratio, vibrotactile feedback, wearable systems * corresponding author rafael escamilla-nunez institute of biomedical engineering, university of toronto, toronto, canada. email: rafael.escamilla@mail.utoronto.ca orcid id: https://orcid.org/0000-0002-2739-878x https://doi.org/10.33137/cpoj.v5i1.36744 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i1.36744 https://doi.org/10.33137/cpoj.v5i1.36744 file:///d:/cpoj/cpoj%20submitted%20articles/accepted-completed/86-eighty%20six-article-cpoj-86-42a-2021-jan-uot-canada/article%20proof/rafael.escamilla@mail.utoronto.ca https://orcid.org/0000-0002-2739-878x 2 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj parameters.9 for instance, individuals with lower limb amputation often have reduced stance time support on the affected limb compared to the intact limb,9 as well as reduced walking speed, cadence,10 poor balance, and increased energy expenditure.11 accordingly, the restoration of gait symmetry is critical for improving mobility, balance, function and efficiency, and overall long-term musculoskeletal health. therefore, achieving gait symmetry is an important goal of gait rehabilitation. gait rehabilitation typically entails motor learning and providing verbal cues related to the patient’s gait deviations or abnormal movement patterns to encourage positive changes. gait rehabilitation is commonly provided by a physiotherapist, and the feedback is usually limited to subjective assessment of movement patterns. additionally, rehabilitation sessions are often limited in duration and frequency.12 patient barriers (e.g., long travel times, accessibility, etc.) and limited resources of healthcare facilities also often restrict access to physiotherapy.12 technology-driven approaches, such as therapy-focused videogames,13 virtual reality,14 and biofeedback (bfb),15,16 have the potential to address the aforementioned challenges and provide alternative and augmentative means of training and rehabilitation in clinical settings or home-based environments. specifically, bfb is the process of measuring physiological/biomechanical parameters and providing the user with real-time information about their current physical status.17 wearable bfb systems for gait training can improve gait patterns by providing real-time, continuous feedback that reinforces good walking habits and physiotherapy goals.16,18 one of the challenges of using bfb for rehabilitation is the establishment of effective feedback strategies and modalities (i.e., how biomechanical information is communicated to the bfb user).19,20 compact and wearable auditory and visual bfb systems are available;16 however, haptic bfb systems may be more suitable for field and community-based applications, since stimuli perception is less prone to be affected by external conditions such as noise or visual distractions.15 however, effectiveness of haptic modalities is highly dependent on the user’s ability to sense, interpret, and appropriately respond to the vibrotactile signals. previous studies have demonstrated the effectiveness of vibrotactile-based bfb systems to alter gait and assessed the impact of varying properties such as vibration amplitude and frequency, location of tactors, interfaces, and pressures on somatosensory response.21-24 however, few studies have applied a systematic approach to explore which bfb strategies most effectively achieve the desired symmetry targets. for instance, afzal et al. tested different feedback strategies based on vibration durations and intensities, finding that greater alterations in gait symmetry occur with proportional vibrotactile feedback.25 lee et al. demonstrated that continuous vibration (i.e., progressive modulation of tactor's intensity) performed better than an on/off vibration approach during dynamic weight-shifting balance training of elderly and individuals with parkinson’s disease.19 while substantial research has been conducted toward developing bfb strategies, to the best of the author’s knowledge, no study has attempted to compare and evaluate multiple vibrotactile biofeedback strategies based on gait symmetry targets, speed, and short-term learning effects when modulating gait symmetry. hence, the overarching goal of this study was to develop a wearable vibrotactile bfb system and evaluate the effect of three unique bfb strategies on temporal gait symmetry and speed. in addition, aspects of learning and short-term retention effects were assessed by evaluating preand post-feedback gait parameters. methodology a. system instrumentation a bfb prototype system was developed that comprised of the following units (figure 1). the vibrating unit (figure 1a) included two vibrating motors (tactors) 9mm in diameter and 25mm in length (model 307-103, precision microdrive, united kingdom). each vibrating motor was supplied with 3.3v, corresponding to a nominal vibration frequency of 250hz and vibration amplitude of 7.5g (i.e., g = 9.8m/s2, the gravity of earth). recent studies suggest that higher frequencies (>230hz), targeting ruffini cylinders and pacinian corpuscles skin mechanoreceptors, increase user detection accuracy and reduce reaction times after vibrotactile stimulation.22,23 the vibrating motors were adhered to the lower abdomen (using surgical tape, transporetm, 3m canada) at the prolongation axis of the rectus femoris muscle following previous studies.26,27 the microcontroller-based control unit (figure 1b) was comprised of the arduino uno rev3 (sparkfun electronics; boulder, colorado, usa) and a custom electronic board with n-type mosfets, diodes, and resistors, which was designed to ensure the correct operation and power supply of the vibrating motors and the sensors/transducer unit. the sensors/transducer unit (figure 1c) included foursquare force sensitive resistors (fsrs) (model 406, interlink electronics, usa) to detect foot contact (heel-strike and toeoff). the fsr’s force sensitivity ranged from 0.2n to 20n. eight fsr sensors (four per foot) were adhered to the shoe sole, underneath the heel (x2) and the 1st and 5th metatarsal heads for the toe (x2). the power supply consists of a 5v at 5ah lithium-ion battery (powercore 5000 by anker innovations, shenzhen, china) powered the entire system. the communication module included a bluetooth serial communication device (hc-05 bluetooth module by smart prototyping, hong kong) which provided wireless communication between the microcontroller and a host pc. https://doi.org/10.33137/cpoj.v5i1.36744 3 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj an open-source software, tera term (tera term project, japan) was utilized for real-time data acquisition and visualization on the host pc at a sampling rate of 100 hz (10ms resolution). a set-up of the bfb system on a participant is shown in figure 1d. b. biofeedback system operation the bfb system employs a closed-loop design to continuously monitor specific gait events, namely heelstrike (hs) and toe-off (to) (figure 2). thus, the symmetry ratio (sr) was calculated to provide real-time biomechanical information via the vibrating motors to alter sr of bfb users. fsr thresholds for hs and to onsets were determined by using a peak detection algorithm presented by lopez-meyer et al.28 the detection of hs and to was used to compute the stance time (st) of each leg. st was defined as the amount of time that each leg remains in contact with the ground during each gait cycle.29,30 subsequently, sr was used to quantify gait symmetry based on the equation:29,30 𝑆𝑅 = 𝑆𝑇𝑛𝑜𝑛−𝑑𝑜𝑚𝑖𝑛𝑎𝑛𝑡 𝑙𝑖𝑚𝑏 𝑆𝑇𝑑𝑜𝑚𝑖𝑛𝑎𝑛𝑡 𝑙𝑖𝑚𝑏 where, st denotes the stance time of the non-dominant and dominant limbs, respectively. sr was measured for each limb and used to provide feedback during the stance phase of the subsequent step.29,30 for non-pathological gait, sr values typically range between 0.95 to 1.05.25 vibrotactile feedback was delivered to users based on the selected feedback strategies (i.e., a combination of vibration levels, vibration thresholds, and control algorithms for one and two motors activation strategies) as detailed below. c. biofeedback strategies three novel strategies were applied that consisted of different vibration/amplitude levels, and number of stimuli (i.e. one or two motors). the three feedback strategies included 1) bidirectional control – constant vibration (bc), 2) bidirectional control – variable vibration (bv), and 3) unidirectional control – variable vibration (uv). bidirectional control (bc and bv) provides feedback when the targeted sr value is either exceeded or not achieved (figure 3a&b). unidirectional control (uv) feedback only provides feedback if the targeted sr value is not achieved (figure 3c). the unidirectional control uses a single vibrating motor, and bidirectional uses two motors (figure 3). vibrating motors are activated at two different vibration levels. a greater deviation from the targeted sr produces a vibration at 100% power, and a smaller error produces vibrations at 50% power. it should be noted that the magnitude of the sr error (i.e., the difference between the targeted sr and the currently measured sr), the pre-set vibration thresholds, and the targeted sr determine the figure 1: main components of the wearable bfb prototype (vibrating motors, microcontroller, bluetooth, power supply, and fsrs sensors). (a) vibrating unit (motors) located at the lower abdomen at the prolongation axis of the rectus femoris muscle. (b) microcontroller-based control unit, including the custom electronic board, the communication (bluetooth) module, and the power supply. (c) sensors/transducer unit comprises four fsrs sensors located at the heel (x2) and toe (x2) of each shoe sole. (d) set-up of the bfb system on a participant. (a) (c) (d) (b) microcontroller custom electronic board power bank (5v, 5ah) bluetooth communication module fsr sensors vibrating motors https://doi.org/10.33137/cpoj.v5i1.36744 4 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj activation and vibration level of the motors according to the applied feedback strategy (figure 3). a tolerance equal to 0.05 was selected based on typical sr values for individuals with non-pathological gait (i.e., 0.95 ≤ sr ≤ 1.05, where sr=1.0 denotes perfect gait symmetry)25 (figure 3). the uv strategy is designed to encourage the bfb user to move toward and exceed the sr target, at which point the vibrotactile feedback stops (figure 3c). strategies bc and bv require the bfb user to maintain sr within specified thresholds (figure 3a&b). figure 2: control diagram of the bfb system to modulate symmetry ratio (sr). the closed-loop system includes system components, feedback strategies, and system operation. biofeedback (bfb) user gait cycle (measured for each limb) heel-strike (hs) toe-off (to) heel-strike (hs)stance phase swing phase sensors/transducer unit fsrs sensors (force sensing resistors) custom electronic board four fsrs sensors per foot (heel x2 and toe x2) for heel-strike (hs) and toeoff (to) gait event detection fsr for to detection fsr for hs detection feedback strategies (fb) control algorithm subject’s-specific control algorithm for hs and to detection, including fsrs threshold and targeted sr. uv : unidirectional control – variable vibration bv : bidirectional control – variable vibration bc : bidirectional control – constant vibration microcontroller-based control unit vibrating motors • one motor (uv) • two motors (bv, bc) vibration level 50% and 100% of full frequency/amplitude level (amplitude: 7.5g, frequency: 250hz) vibrating unit vibration frequency/amplitude levels, vibration thresholds, including one and two motors vibration strategies. hs and to detection motor activation based on feedback and targeted sr v ib ro ta c ti le fe e d b a c k t o a lt e r g a it s y m m e tr y ( i. e ., s y m m e tr y r a ti o – s r ) o f b f b u s e rs st and sr calculation microcontroller vibrating motors fsrs sensors microcontroller vibrating motors fsrs sensors https://doi.org/10.33137/cpoj.v5i1.36744 5 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj b id ir e c ti o n a l c o n tr o l – c o n s ta n t v ib ra ti o n “ b c ” b id ir e c ti o n a l c o n tr o l – v a ri a b le v ib ra ti o n “ b v ” u n id ir e c ti o n a l c o n tr o l – c o n s ta n t v ib ra ti o n “ u v ” f e e d b a c k 02 t f e e d b a c k n o f e e d b a c k b c f e e d b a c k t a rg e te d s rs r m 2 @ 1 0 0 % m 1 @ 1 0 0 % u p p e rt h r * l o w e rt h r m 2 @ 5 0 % u p p e rt h r m 1 @ 5 0 % m 1 @ 1 0 0 % m 2 @ 1 0 0 % f e e d b a c k 02 t f e e d b a c k n o f e e d b a c k b v f e e d b a c k t a rg e te d s r l o w e rt h r to le ra n c e s r l o w e rt h r u p p e rt h r + t o le ra n c e u v f e e d b a c k m 1 @ 5 0 % m 1 @ 1 0 0 % 02 t f e e d b a c k n o f e e d b a c k t a rg e te d s r l o w e rt h r l o w e rt h r t o le ra n c e s r * th r = t h re sh o ld n o v ib ra ti o n / n o f e e d b a c k : l o w e rt h r ≤ s r ≤ u p p e rt h r m 1 @ 1 0 0 % : s r < l o w e r t h r m 2 @ 1 0 0 % : s r > u p p e r t h r b c = n o v ib ra ti o n / n o f e e d b a c k : l o w e rt h r ≤ s r ≤ u p p e rt h r m 1 @ 5 0 % : l o w e rt h r – to le ra n c e < s r < l o w e rt h r m 2 @ 5 0 % : u p p e rt h r < s r < u p p e rt h r + t o le ra n c e m 1 @ 1 0 0 % : s r < l o w e r t h r to le ra n c e m 2 @ 1 0 0 % : s r > u p p e r t h r + t o le ra n c e b v = n o v ib ra ti o n / n o f e e d b a c k : l o w e rt h r ≤ s r m 1 @ 1 0 0 % : l o w e rt h r – to le ra n c e < s r < l o w e r t h r m 1 @ 5 0 % : s r < l o w e rt h r – to le ra n c e u v = (a ) (b ) (c ) d a ta c o ll e c ti o n s e s s io n s ta rt t ri a ls b f b s e tu p in it ia l b a s e li n e s e t f s r t h re s h o ld , v ib ra ti o n th re s h o ld s , a n d t a rg e te d s r 5 -1 0 m in x 2 x 2 x 6 e n d t ri a ls x 2 n o f e e d b a c k (n f ) n o f e e d b a c k (n f ) r a n d o m iz e d f e e d b a c k (b c , b v , u v ) t ra in in g (u v , b c , b v ) 1 0 m in x 3 p e r c o n d it io n b re a k f ig u re 3 : v ib ro ta c ti le f e e d b a c k s tr a te g ie s . (a ) b c : b id ir e c ti o n a l c o n tr o l – c o n s ta n t v ib ra ti o n ; (b ) b v : b id ir e c ti o n a l c o n tr o l – v a ri a b le v ib ra ti o n ; a n d ( c ) u v : u n id ir e c ti o n a l c o n tr o l – v a ri a b le v ib ra ti o n . b c u ti liz e s t w o m o to rs ( m 1 & m 2 ), w h ic h p ro d u c e v ib ra ti o n s a t 1 0 0 % o f fu ll v ib ra ti o n f re q u e n c y /i n te n s it y . b v u ti li z e s t w o m o to rs , w h ic h p ro d u c e v ib ra ti o n s a t 5 0 % a n d 1 0 0 % o f fu ll v ib ra ti o n f re q u e n c y /i n te n s it y . a n d , u v u ti liz e s o n ly o n e m o to r (m 1 ), w h ic h p ro d u c e s v ib ra ti o n s a t 5 0 % a n d 1 0 0 % o f fu ll v ib ra ti o n f re q u e n c y /i n te n s it y . m o to rs “ m 1 ” a n d “ m 2 ” w e re p la c e d a t th e le ft a n d r ig h t s id e o f th e l o w e r a b d o m e n a t th e p ro lo n g a ti o n a x is o f th e r e c tu s f e m o ri s m u s c le , re s p e c ti v e ly . v ib ra ti n g t h re s h o ld s a re d e n o te d b y l o w e rt h r a n d u p p e rt h r f o r lo w e r a n d u p p e r th re s h o ld s , re s p e c ti v e ly . t h e d e s ir e d s r v a lu e i s d e n o te d b y t a rg e te d s r . a t o le ra n c e o f 0 .0 5 w a s s e le c te d b a s e d o n t y p ic a l s r v a lu e s f o r in d iv id u a ls w it h n o n -p a th o lo g ic a l g a it ( i. e ., 0 .9 5 ≤ s r ≤ 1 .0 5 , w h e re s r = 1 .0 d e n o te s p e rf e c t g a it s y m m e tr y ). f ig u re 4 : e x p e ri m e n ta l p ro to c o l fo r th e d a ta c o lle c ti o n s e s s io n . b a s e lin e t ri a ls c o n s is t o f w e a ri n g t h e b f b s y s te m , b u t n o f e e d b a c k ( n f ) is p ro v id e d . f e e d b a c k s tr a te g ie s ( b c , b v , u v ) w e re ra n d o m iz e d f o r d a ta c o lle c ti o n . b c : b id ir e c ti o n a l c o n tr o l – c o n s ta n t v ib ra ti o n , b v : b id ir e c ti o n a l c o n tr o l – v a ri a b le v ib ra ti o n , a n d u v : u n id ir e c ti o n a l c o n tr o l – v a ri a b le v ib ra ti o n . https://doi.org/10.33137/cpoj.v5i1.36744 6 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj previous studies suggest that permanent gait changes must be achieved gradually,30 finding that absolute differences larger than 5% can be considered as potential improvement or deterioration of gait symmetry.31 for this reason, all feedback strategies (bc, bv, uv) targeted srs that were 10% greater than an initial sr baseline (e.g., mean initial sr baseline = 1.0; targeted sr = 1.10), as proposed by.25 sr converging towards 1, indicates an improvement in gait symmetry, whereas sr diverging from 1, indicates a deterioration.31 since this study involved participants with non-atypical gait symmetry (i.e., sr = 1 ± 0.05), the testing paradigm consisted of deviating sr from sr = 1 to alter gait symmetry. for all the feedback strategies, vibrations (if provided) start at hs and end at to of the same limb within a gait cycle. vibrations are only provided if participants are walking with a sr value outside of the pre-set vibrating thresholds (figure 3). d. participants the study involved a convenience sample of ten (n=10) healthy subjects (five males), age 24.8 ± 4.4yrs; height 1.7 ± 0.1m; weight 68.7 ± 14.4kg. participants were 18 years or older, were all english speaking, and having no physical or gait-related impairments, ambulation difficulties or neuromotor disorders. the study was approved by the research ethics board (reb #16-675) at holland bloorview hospital, canada. informed written consent was obtained from each participant before commencing. e. experimental protocol data were collected in a single session. participants were instrumented with the bfb system (figure 1). training was provided before collecting data (figure 4). training consisted of a brief explanation about the bfb operation and the opportunity to walk using each feedback strategy (bc, bv, uv). during training, participants were coached about how to interpret the vibrotactile feedback. to determine limb dominance, participants were asked about what foot they use to kick a ball. all participants were right footed (i.e., right limb was the dominant limb). for the uv strategy, the vibrating motor (m1) was placed on the nondominant (left) side at the lower abdomen level. for the bv and bc strategies, motor m1 was placed on the nondominant (left) side and the second motor (m2) on the dominant (right) side at the lower abdomen. since the goal was to achieve a 10% change in sr (i.e., increase st on the non-dominant “left” limb), verbal instruction and cues were provided as follow: for uv strategy (motor m1 placed on the non-dominant side), “if the motor on your left side vibrates, you need to spend more time in contact with the ground on that (left) side”. hence, for bv and bc strategies, a verbal instruction/cue for motor m2 was provided in addition to the one provided for m1, “if the motor on your right side vibrates, you are spending too much time on your left side, so you just need to spend a little bit less time in contact with the ground on your left side”. in terms of the vibration levels, cues consisted of “while walking, you will experience two different vibration intensities, the weaker vibration means you are closer to the target, and stronger means you are farther from the target. the goal is to receive no vibration”. for the data collection, each participant performed 30 walking trials in total (i.e., 4 no feedback trials plus 6 feedback trials for each of the three strategies). each trial consisted of walking 20 meters in a straight line at a self-selected speed. feedback strategies (bc, bv, uv) were randomized using simple and balanced randomization through a random number generator. no feedback “nf” condition was performed before (x2 trials) and after (x2 trials) each feedback strategy. both nf conditions (before and after feedback) were used as a baseline to compare bfb effects within strategies. average gait speed was calculated for each trial based on the walking distance and time recorded with a stopwatch. the magnitude of the sr error was calculated for each gait cycle as the difference between the targeted sr and the measured sr. the percentage of vibration was calculated based on the activation status of each motor, which indicates the number of times that the motors were activated (on = 1) or deactivated (off = 0) for each trial (i.e., time (on/(on + off))*100). f. data analysis data recorded and captured using teraterm software (tera term project, japan) were exported to excel (microsoft corp; redmond, washington) and processed in matlab 2019b (r2019b, mathworks, ma, usa) to extract parameter values (i.e., sr, sr error, average gait speed, and percentage of vibration) for each trial, condition, and participant. statistical analysis was performed using jmp pro 2019 software (statistical discovery, sas, usa). a shapiro-wilk w test with an alpha level of 0.05 was used to confirm the assumption of normal distribution of the data. a multivariate analysis of variance (manova) was performed between and within participants, trials, and conditions (nf, bc, bv, uv) across all retrieved parameters. statistical significance was determined using a critical alpha level of 0.05 for all primary analyses. if statistically significant differences were found, a fit model – mixed model analysis with a post-hoc tukey hsd all pairwise comparisons analysis was performed to identify which particular differences between pairs of means were significant. in addition, a paired t-test was performed to compare differences on the level of precision with which the targeted sr was achieved between conditions (nf, bc, bv, uv). for this test, the standard deviation of the sr values was used. finally, a paired t-test was used to compare sr values between nf conditions (i.e., nf before and after vibrotactile feedback) to identify statistically significant short-term retention effects. a bonferroni correction with an https://doi.org/10.33137/cpoj.v5i1.36744 7 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj adjusted critical alpha level of 0.008 (p = 0.05/6) was applied to reduce type i errors for multiple pairwise comparisons. results a. biofeedback strategies effectiveness changes on sr values were found statistically significant when comparing between the feedback strategies (bc, bv, uv) and the no feedback (nf) condition (p < .001). significant differences were also found within feedback strategies. uv produced a larger change in sr than bv (p < .001) and bc (p < .001) (figure 5). however, changes in sr values between strategies bv and bc were not significantly different (p = 0.708). in terms of the sr error, all bfb strategies resulted in larger sr errors that were statistically different from nf (nf–bc: p < .001; nf–bv: p < .001; and nf–uv: p < .001) (figure 6). there were also statistically significant differences among the sr errors for bc–uv (p < .001) and bv–uv (p < .001) strategies, but not among bc–bv (p = 0.512). further, when comparing the standard deviation of sr, nf achieved a higher level of precision (smaller variability) compared than all the feedback strategies (p < .001; bc, bv, uv). however, no significant differences in the level of precision (i.e., standard deviation of sr) were found between feedback strategies (bc-uv: p = 0.057; bc–bv: p = 0.065; and bv–uv: p = 0.752). b. short-term retention and learning effects in terms of short-term retention, no significant effects (p = 0.156) were evident from figure 7, and based on the paired t-test statistical analysis of nf before (i.e., nf1) and after (i.e., nf2) vibrotactile feedback (bc, bv, uv). learning effects for trial*feedback interactions within subjects were not statistically significant (figure 8). however, for bv and uv strategies, participants neared the targeted sr from the first trial, with a slight but nonsignificant trend towards improvement in subsequent trials (figure 8). c. secondary outcomes all feedback conditions were associated with significantly slower walking speeds compared to the nf condition which was 1.398 m/s ± 0.022 (p < .001). when comparing walking speed between feedback strategies (bc, bv, uv), participants walked significantly faster with uv feedback (1.206 ± 0.029 m/s, p < .001) than bv (1.067 ± 0.023 m/s, p < .001) and bc (1.053 ± 0.020 m/s, p < .001). no significant differences in walking speeds were found between bv and bc (p = 0.900). figure 5: sr vs fb. box plot of sr values for all feedback (bc, bv, and uv) and no feedback (nf) conditions. bc: bidirectional control – constant vibration; bv: bidirectional control – variable vibration; uv: unidirectional control – variable vibration. statistically significant differences between conditions are denoted with an ‘*’. mean, standard deviations (std dev), maximum, median, and minimum values of sr are presented. upper and lower thresholds labeled as upper_thresh and lower_thresh, respectively. nf bc bv uv feedback condition sr across feedback conditions s y m m e tr y r a ti o ( s r ) baseline = 1.0 0.95 1.20 1.25 1.30 target_sr = 1.10 upper_thresh = 1.15 lower_thresh = 1.05 mean std dev max median min 0.995 0.016 1.040 1.000 0.960 1.086 0.037 1.190 1.080 1.000 1.083 0.030 1.180 1.080 1.010 1.104 0.043 1.200 1.100 1.000 * * * * * https://doi.org/10.33137/cpoj.v5i1.36744 8 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj figure 6: sr error. mean sr error values across feedback (bc, bv, uv) and no feedback (nf) conditions. bc: bidirectional control – constant vibration; bv: bidirectional control – variable vibration; uv: unidirectional control – variable vibration. statistically significant differences were found between nf and feedback conditions (bc, bv, and uv), including between feedback strategies uv-bc and uv-bv, but not between bc – bv strategies. statistically significant differences are denoted with an ‘*’. mean and standard deviations (std dev) are listed above. sr error across feedback conditions nf uv feedback conditions bc bv -0.10 -0.08 -0.06 -0.04 -0.02 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 s r e rr o r -0.10 0.08 0.10 0.12 mean std dev 0.005 0.016 0.014 0.037 0.017 0.030 -0.004 0.043 * * * * * figure 7: short-term retention. box plot of sr values during no feedback (nf) before (i.e., nf1) and after (i.e., nf2) providing vibrotactile feedback (bc, bv, uv). bc: bidirectional control – constant vibration; bv: bidirectional control – variable vibration; uv: unidirectional control – variable vibration. statistically significant differences were found only between nf and feedback conditions. mean and standard deviations (std dev) are also included above. upper and lower thresholds labeled as upper_thresh and lower_thresh, respectively. 0.95 nf1 fb nf2 uvbvbc short-term retention (nf vs fb) sr target = 1.10 lower_thresh = 1.05 upper_thresh = 1.15 baseline = 1.0 s y m m e tr y r a ti o ( s r ) 1.20 mean std dev 0.992 0.013 1.086 0.037 0.997 0.021 0.996 0.016 1.083 0.030 0.996 0.015 0.994 0.016 1.104 0.043 0.995 0.016 feedback conditions nf1 nf1fb fbnf2 nf2 https://doi.org/10.33137/cpoj.v5i1.36744 9 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj the percentage of vibration was significantly smaller under uv feedback (21%) compared to bv (27%), and bc (52%). the post-hoc tukey hsd analysis showed a significant vibration percentage difference between conditions bc and uv (p < .001) and, bc and bv (p < .001). there was no significant difference in the vibration percentage between uv and bv (p = 0.959). discussion the purpose of this study was to investigate the effect of bfb on sr and walking speed via three novel vibrotactile feedback strategies (bc, bv, uv), which are different combinations of vibration thresholds, vibration levels (frequencies/amplitudes), and control strategies based on the activation of one and two motors. these feedback strategies were utilized to provide somatosensory information to bfb users to modulate gait symmetry during walking. in addition, learning effects and short-term retention were investigated. during walking trials, all participants were able to utilize bfb somatosensory information to alter their gait performance towards the targeted symmetry ratios (sr). accordingly, results showed that bc, bv, and uv feedback strategies can all potentially modulate sr of bfb users. the results also suggest that a unidirectional strategy (uv) can produce a greater change in sr, to bring it closer to the target value (lower se error). hence, uv more accurately achieved the target sr as compared to both bc and bv. while the precision (variability) was not significantly different among feedback strategies, based on figure 5 and figure 6 the bidirectional strategies (bc and bv) trended toward more precise changes in sr (i.e., error bars are larger for uv compared to bc and bv). this may be due to the target being exceeded more frequently (i.e., sr higher than set target). in contrast, the bidirectional strategies (bc and bv) having both an upper and lower limit around the target values, produced less variability. it must be noted that among all of the conditions, participants achieved the lowest sr variability in the nf condition. one approach to achieve both accuracy and precision would be to use a bidirectional strategy with an adaptive targeted sr control, by which the target sr is gradually increased as the user changes their sr. this technique may reduce variability by guiding users to perform smaller step-to-step increments. figure 8: learning effects. box plot of sr values for mean sr values of all participants across trials during no feedback (nf) and feedback conditions (bc, bv, uv). bc: bidirectional control – constant vibration; bv: bidirectional control – variable vibration; uv: unidirectional control – variable vibration. no statistically significant differences were found among conditions. mean and standard deviations (std dev) are also included above for each trial. upper and lower thresholds labeled as upper_thresh and lower_thresh, respectively. upper_thresh = 1.15 lower_thresh = 1.05 target sr = 1.10 s y m m e tr y r a ti o ( s r ) baseline = 1.0 0.95 1.20 1.25 1.30 nf bc bv uv feedback conditions sr across trials and feedback conditions (trial 1) (trial 2) (trial 3) (trial 4) (trial 5) (trial 6) mean 0.990 0.997 0.995 0.996 0.997 0.995 mean 1.087 1.091 1.080 1.080 1.101 1.080 mean 1.084 1.081 1.076 1.081 1.089 1.089 mean 1.094 1.105 1.099 1.103 1.114 1.111 std dev 0.016 0.016 0.013 0.020 0.016 0.015 std dev 0.039 0.042 0.029 0.035 0.037 0.036 std dev 0.033 0.032 0.031 0.026 0.030 0.028 std dev 0.039 0.047 0.043 0.040 0.046 0.041 trial 1 trial 2 trial 3 trial 4 trial 5 trial 6 https://doi.org/10.33137/cpoj.v5i1.36744 10 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj few differences were evident between the variable and constant bidirectional strategies (i.e., bv and bc, respectively), suggesting limited effectiveness in using vibration levels for thresholding. in this study the two distinct levels of vibration (both frequency and amplitude) were applied based on the magnitude of the error and pre-set vibration thresholds. previous studies have resorted to altering duration of vibrations;27,30,32,33 and, only few of them have used variable amplitudes.19,25 in terms of the effectiveness of the vibration pattern (i.e., continuous versus corrective versus on/off or discrete feedback), the previous research findings are mixed. some studies suggest that continuous feedback (i.e., progressively incrementing or decrementing motor's intensity) produce greater gait improvements over discrete feedback (i.e., motors on/off activation);19 and vice versa.27,34 whereas, others suggest that corrective feedback (e.g., vibration only if targeted value is not reached) can elicit greater effects compared to continuous feedback (e.g., vibration until targeted value is reached).32 the present study combines discrete signals (on/off) with corrective feedback, adding multiple vibration levels and thresholds, which provides the bfb system with unique feedback strategies to modulate gait symmetry of bfb users. in this study we found the bfb learning effects and shortterm retention to be minimal. according to the literature, learning a new skill or eliciting a locomotor adaptation is a complex process that involves motor adaptation, skill acquisition, and decision-making.35,36 the process of motor learning occurs gradually and improves over time. the learning process, at early stages, demands high cognitive effort, high consciousness of the task performed, and greater amounts of energy. however, at later stages, the movements seem to occur more unconsciously, automatically, and with less effort.36 it is plausible that extended use of the bfb system may result in relearning, and retention whereby the modified gait patterns would be preserved once the bfb system is no longer active. for instance, a recent study showed that 1 out of 3 above-knee amputee participants were able to retain improvements in gait symmetry (+14.9% improvement compared to baseline) after three training sessions of using vibrotactile feedback, suggesting an effective motor learning at least in the shortterm.37 the slower than normal walking speeds associated with the provision of bfb, indicate potential limitations in terms of bfb effectiveness. however, it is foreseeable, that over the longer term as users utilize bfb less consciously, walking speeds may naturally recover towards normal values. moreover, when feedback was provided, uv feedback achieved a significantly faster walking speed compared to bv and bc. uv also resulted in less vibrotactile feedback (vibration percentage) compared to bv and bc. together, these results may indicate that as the complexity of the feedback strategy and information provided to bfb user increases, thus taxing of the executive function (i.e., cognitive processes), slower execution of function (e.g., slower motor response to stimulation) results. it might be beneficial for new bfb users to start the gait retraining with uv feedback. once uv is learned, treatment can move progressively to bv or bc strategies. future iterations of the bfb system should incorporate visual or auditory feedback modalities to assess the effectiveness of multimodal feedback paradigms. in addition, future studies should have in mind that individuals with poor somatosensory function might have decreased sensory perception to stimulus detection, which might affect the performance of haptic bfb systems. however, the stochastic resonance phenomenon, which consists of delivering sub-threshold noise to the somatosensory system might be a promising alternative for enhancing sensitivity to sensory inputs,38 and for improving reaction times.39 accordingly, traditional haptic bfb systems can be combined with a noise-generating device/module to enhance bfb sensory perception to improve gait asymmetries. also, the effects of haptic bfb systems on the tonic vibration reflexes (i.e., reflex muscular contraction) and the excitatory and inhibitory responses of the muscle spindle, which play a role enhancing muscle activation should be further investigated, since acute indirect vibrations acting on muscles can potentially enhance force, power, flexibility, balance, and proprioception, which might suggest neural enhancement.40 this study has several limitations. the limited sample size of healthy subjects with non-asymmetrical gait represented a main limitation for generalizable conclusions. thus, the performance of the bfb system in populations with pathological gait remains to be studied. additionally, pressure sensors had a tendency to degrade over time resulting in inconsistent measurements. in such instances where measurements became unreliable, sensors were replaced, and additional data collected within the session. however, the development of a clinically relevant system will require more robust sensing instrumentation. to address the measurement issues with the fsrs, and also improve wearability, inertial measurement units should be considered. a final potential limitation relates to the sound generated by the vibrating motors. it is possible that it may have contributed to the feedback received by the participants. thus, using headphones to cancel external sources of noise might be a point of consideration for future studies involving haptic feedback. as part of future work, secondary/indirect changes in gait patterns (either improvements or detriments) due to bfb should be investigated. finally, longer-term use of bfb is needed to assess learning and retention effects. https://doi.org/10.33137/cpoj.v5i1.36744 11 escamilla-nunez r, sivasambu h, andrysek j. exploration of vibrotactile biofeedback strategies to induce stance time asymmetries. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.2. https://doi.org/10.33137/cpoj.v5i1.36744 issn: 2561-987x vibrotactile biofeedback escamilla-nunez et al., 2022 cpoj conclusion in this paper, the development of a wearable vibrotactile bfb system was presented along with the evaluation of three novel feedback strategies to modulate temporal gait symmetry by inducing stance time asymmetries. clinical testing of the bfb prototype showed its ability to alter sr during walking; however, no learning effects or short-term retention effects were found. acknowledgements the authors would like to thank össur hf. for their continuous support and for reviewing the manuscript. declaration of conflicting interests the authors declare no conflict of interest. the funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. author contribution • rafael escamilla-nunez: conceptualization, methodology, validation, formal analysis, investigation, writing—original draft preparation, writing/review and editing, visualization, funding acquisition. • harry sivasambu: validation, formal analysis, investigation, writing/review and editing, visualization. • jan andrysek: supervision conceptualization, methodology, investigation, writing/review and editing. sources of support this research was funded by natural sciences and engineering research council of canada (nserc) discovery rgpin 201805046, nserc crd crdpj 491125 – 15, and mexico’s national council for science and technology (conacyt). ethical approval the study was approved by the 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feedback and training. ieee/asme trans mechatronics. 2012;17:425–33. doi:10.1109/tmech.2012. 2189014 31.pagel a, arieta ah, riener r, vallery h. effects of sensory augmentation on postural control and gait symmetry of transfemoral amputees: a case description. med biol eng comput. 2016;54:1579–89. doi:10.1007/s11517-015-1432-2 32.plauche a, villarreal d, gregg rd. a haptic feedback system for phase-based sensory restoration in above-knee prosthetic leg users. ieee trans haptics. 2016;9:421–6. doi:10.1109/ toh.2016.2580507 33.maldonado-contreras j, marayong p, khoo i-h, rivera r, ruhe b, wu w. proprioceptive improvements of lower-limb amputees under training with a vibrotactile device — a pilot study. 2017 ieee healthc innov point care technol. 2017;229–32. doi: 10.1109/hic.2017.8227626 34.crea s, cipriani c, donati m, carrozza mc, vitiello n. providing time-discrete gait information by wearable feedback apparatus for lower-limb amputees: usability and functional validation. ieee trans neural syst rehabil eng. 2015;23:250–7. doi: 10.1109/tnsre.2014.2365548 35.kitago to, krakauer jw. motor learning principles for neurorehabilitation. handb clin neurol. 2013;110:93-103. doi: 10.1016/b978-0-444-52901-5.00008-3 36.cech dj, martin s “tink.” functional movement development across the life span. third edition. elsevier. 2012; p. 68–87. doi:10.1016/b978-1-4160-4978-4.00004-1 37.martini e, cesini i, d’abbraccio j, arnetoli g, doronzio s, giffone a, et al. increased symmetry of lower-limb amputees walking with concurrent bilateral vibrotactile feedback. ieee trans neural syst rehabil eng. 2021;29:74–84. doi:10.1109/ tnsre.2020.3034521 38.gopalai aa, lan bl, gouwanda d. stochastic resonance for enhancing sensory perception: an emerging trend for adl rehabilitation. tencon 2015 2015 ieee region 10 conference, 2015, pp. 1-5. doi:10.1109/tencon.2015.7373098 39.collins jj, priplata aa, gravelle dc, niemi j, harry j, lipsitz la. noise-enhanced human sensorimotor function. ieee eng med biol mag. 2003;22:76–83. doi:10.1109/memb.2003.1195700 40.cochrane dj. the potential neural mechanisms of acute indirect vibration. j sports sci med. 2011;10:19–30. https://doi.org/10.33137/cpoj.v5i1.36744 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives fiedler g, schikorra a. a brief introduction to game theory and its potential implications for the economics of orthotics & prosthetics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.18. https://doi.org/10.33137/cpoj.v4i2.36661 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.36661 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 fiedler g, schikorra a. a brief introduction to game theory and its potential implications for the economics of orthotics & prosthetics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.18. https://doi.org/10.33137/cpoj.v4i2.36661 stakeholder perspectives a brief introduction to game theory and its potential implications for the economics of orthotics & prosthetics fiedler g.1 *, schikorra a.2 1 university of pittsburgh, department of rehabilitation science and technology, pittsburgh, usa. 2 university of pittsburgh, department of mathematics, pittsburgh, usa. background the costs of health care provision in the united states is estimated to exceed $4 trillion (t) in the year 2020.1 more than half of this amount is expended for hospital care ($1.3t) and physician and clinical services ($794b). prescription drugs account for $358b, or about 9%. by comparison, only $62b, representing about 1.5% of the total, go into durable medical equipment of which orthotics and prosthetics (o&p) devices are a subsection.1 this distribution correlates with the size of the involved industries and their respective lobbying budgets. data from the u.s. bureau of labor statistics suggests that more than 750,000 physicians and more than 320,000 pharmacists were employed in 2019, which compares to a total of 10,000 o&p jobs nationwide.2 according to the center for responsive politics, the pharmaceutical industry spent more than $300m on lobbying in 2020, followed by hospitals/nursing homes with more than $100m.3 by comparison, the o&p alliance, which is representing the interests of the main professional o&p organizations, had a lobbying budget of $60,000.3 another measure of the disparity between o&p and other health professions is the amount of scientific evidence that informs their practice. the comparably small size of the o&p field corresponds with a small number of researchers working in this field and the associated number and quality of scientific publications.4-6 overall, of course, this apparent imbalance is in large parts reflective of the patient populations tended to by the respective specialists. however, on the scale of individual patient cases there is, nonetheless, an overlap of competencies and a need for the entire health care team to collaboratively decide on the best treatment. additional stakeholders include the patient and/or their family, as well as third-party payers, such as private and institutional health insurers or respective government agencies. if, in the example of a progressing orthopedic condition, it is to be decided whether conservative treatment or surgical intervention is called for, a variety of explicit and implicit interests of these stakeholders need to be reconciled. the patient is likely to prioritize the subjectively most promising and convenient treatment irrespective of the costs, whereas the insurer is interested in the most cost-effective treatment, which ideally includes a consideration of long-term costs. open access volume 4, issue 2, article no.18. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract the economic viability of orthotics & prosthetics (o&p) service provision is an important concern for policy makers, patients, and practitioners. against the background of limited funds that can be distributed for healthcare expenses overall, it is critical to identify the most cost-effective treatment options within and across disciplines, including surgical and pharmacological interventions. when those decisions are being negotiated, whether in the context of an individual case in the clinic or of general payer policies that allocate spending budgets, the o&p discipline is often perceived to be at a disadvantage due to its relatively young age, underdeveloped evidence base, and small economic clout as compared to other fields. such asymmetrical negotiations have been the subject of economic theories and mathematical models, such as the “game theory”, work on which has been awarded with several nobel prizes and other recognitions across the years. in this paper, we are introducing core concepts of this theory and discuss how they may be applied in negotiations on treatment approaches and reimbursement schedules with the goal to improve outcomes for the o&p profession. citation fiedler g, schikorra a. a brief introduction to game theory and its potential implications for the economics of orthotics & prosthetics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.18. https://doi.org/10.33137/cpoj.v4i2.36661 keywords healthcare economics, game theory, rehabilitation, competitive bidding * corresponding author dr. goeran fiedler, phd department of rehabilitation science and technology, university of pittsburgh, pittsburgh, pa 15206, usa. e-mail: gfiedler@pitt.edu orcid number: https://orcid.org/0000-0003-1532-1248 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.36661 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.36661 mailto:gfiedler@pitt.edu https://orcid.org/0000-0003-1532-1248 2 fiedler g, schikorra a. a brief introduction to game theory and its potential implications for the economics of orthotics & prosthetics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.18. https://doi.org/10.33137/cpoj.v4i2.36661 issn: 2561-987x a brief introduction to game theory in p&o fiedler & schikorra, 2021 cpoj special s p e c ia l i s s u e for the healthcare professionals, the eventual decision will have obvious economic implications as well. the surgeon’s recommendation, by nature, may be biased toward surgical treatment, just as the orthotist’s recommendation may favor bracing. a similar dynamic applies when insurance coverage and reimbursement schedules are being established and/or revised. the process of arriving at the decision can by some definition be considered a negotiation. with the comparative prestige of their academic degree and the amount of citable evidence to support their case likely not on the side of the o&p practitioners in this scenario, they may be at a disadvantage in such a negotiation. a different problem is that of competing against another provider. there may be various examples of this occurring in everyday practice but an instance with especially high stakes is the dreaded competitive bidding process that is frequently utilized, or at least proposed, by institutional payers, including the centers for medicare and medicaid services.7 in some such scenarios, o&p providers may have to contend against other bidders from outside the actual profession. if those competitors have a different cost structure, for instance, by being subject to different education and licensing requirements or by having lower local costs for labor and parts, the bidding process is unlikely to be effective in optimizing the economics of the contract at stake. instead, it may happen that the expert o&p provider is priced out and the winning bid does not cover the costs of providing quality care, to the detriment of the patient, the provider, and ultimately, the insurer as well. these scenarios pose the question if there are strategies to optimize the outcomes under a given (or assumed) set of circumstances. an answer to that question may be offered by game theory, chiefly a set of mathematical models to describe and predict negotiation dynamics, which has been recognized as an important concept in economics.8,9 the mathematical basis of game theory for simplicity we focus here on so-called non-cooperative games of, for example, two decision makers (called the players). our game is pretty short and simple: each of the players makes a decision and receives a payout (or has to pay) according to some rules. take, as an example, two doctors who have to decide which treatment to prescribe for a certain type of illness. let us say, treatment 1 costs $900, and treatment 2 costs $1,000. if both doctors agree that treatment 2 is better, they will likely (in the long run) receive both 50% of the patients to treat. if, however, one of the doctors decides to prescribe treatment 1 (even though treatment 2 might be better), the insurance has – all else being equal – an incentive to choose the doctor that is cheaper. knowing this, both doctors have an incentive to prescribe treatment 1 (even though it may be not the optimal treatment) for the fear of losing all revenue. so, according to this model both doctors are coerced to recommend the cheaper treatmentregardless of the qualitative advantages of treatment 2 (table 1). table 1: payout structure for each possible combination of prescription decisions. in mathematical terms the choice for treatment 1 is called the nash equilibrium: it is a choice where, for each player, the other party cannot improve their outcome by changing strategies. the problem that the nash equilibrium may not be the optimal outcome for the participants is called prisoners’ dilemma of game theory. and this effect has been observed in many real-world situations (e.g., in social psychology or drug cartel formation).10,11 the mathematical models (and summary tables) for this sort of real-life situation quickly become much more complex if additional parameters are being considered. in the simplified example of a “cardinal game” above, for instance, the insurance is making decisions solely by price tag, which may not be entirely realistic. if the outcomes are on an ordinal scale rather than binary as in this example, or if there are additional differences between providers (e.g., qualifications, seniority, etc.) that affect the decision making, the model needs to be expanded and the additional assumptions need to be codified to allow for calculation of the nash equilibrium. implications for negotiations in the o&p realm it may not be immediately obvious how the dynamics of a “prisoners’ dilemma” could apply to the realm of o&p related economics. indeed, most of the typical scenarios with which stakeholders in this field are confronted can be explained (and possibly solved) as a simple optimization problem. for instance, a negotiation with a payer (health insurance) about whether to give a transfemoral prosthesis patient a conventional hydraulic knee joint or a microprocessor-controlled knee can be reduced to a fairly straightforward balancing of costs and benefits. the cost differential is well known, and the risks of, say, accidental fall(s) that are detrimental to quality of life and follow-on health care cost savings12,13 can be reasonably approximated using historical data and a probabilistic doctor 2’s prescription treatment 1 ($900) treatment 2 ($1000) doctor 1 gets doctor 2 gets doctor 1 gets doctor 2 gets doctor 1’s prescription treatment 1 50% of 900 50% of 900 100% of 900 0% of 1000 treatment 2 0% of 1000 100% of 900 50% of 1000 50% of 1000 https://doi.org/10.33137/cpoj.v4i2.36661 3 fiedler g, schikorra a. a brief introduction to game theory and its potential implications for the economics of orthotics & prosthetics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.18. https://doi.org/10.33137/cpoj.v4i2.36661 issn: 2561-987x a brief introduction to game theory in p&o fiedler & schikorra, 2021 cpoj special s p e c ia l i s s u e distribution curve. these factors will allow the recommendation to utilize either knee type at a specific ratio to optimize outcomes for all involved (at least on average). a more suitable application may be found in the competitive bidding process. an aspect of this process in the o&p field is the, theoretically, unlimited number of bidders (i.e., players), as well as a large number of contractual terms and performance criteria, making it difficult to model as a cardinal game, which has a specific payoff function. instead, a more complex ordinal game theory approach may be appropriate. recent work14 suggests that such a model and associated optimization algorithm is applicable to general variants of public-private partnerships, claiming that, among other things, “(1) it can handle any number of private sector players and … performance criteria, (2) it determines a single ranking of proposals ..., [and] (3) it can be used by the private sector players … to assist with the choice of bidding strategies…”.14 given the inevitable differences between the specific scenarios considered in this research and the real-world process of entering a bid in, say, the cms durable medical equipment, prosthetics, orthotics, and supplies (dmepos) competitive bidding program, more work to validate and refine the model is likely required. this work will include a discipline-specific ranking of the “strategy profile-induced outcomes”, to include things such as long-term health outcomes, processing efficiency, and sustainability of the provider pool. still, it offers an interesting approach to maximizing the limited leverage wielded by o&p providers in the competitive bidding process and to optimize the bid evaluation and contracting process by the payer. call to action the long-term health and sustainability of our industry requires a mitigation of the inherent disadvantage that small-size businesses, such as typical o&p providers, have in competitive bidding and contract negotiations. we believe that modern game theory is a tool that can help address this issue, and we call on the large professional organizations that represent and cater to those businesses (e.g., the american orthotic & prosthetic association and the o&p alliance) to explore ways to take advantage of this powerful tool. this effort could take the shape of adding game theory content to business training offerings, or providing grant support for the development of industry-specific game theory models. acknowledgements the authors thank dave crish for proofreading the manuscript. declaration of conflicting interests the authors declare no conflicts of interest related to this work. sources of support this work was partially supported by simons foundation grant no 579261 and by nsf career dms-2044898 references 1.keehan sp, cuckler ga, poisal ja, sisko am, smith sd, madison aj, et al. national health expenditure projections, 2019– 28: expected rebound in prices drives rising spending growth: national health expenditure projections for the period 2019–2028. health aff. 2020;39(4):704-14. doi:10.1377/hlthaff.2020.00094 2.us department of labor, bureau of labor statistics. occupational outlook handbook [internet]. 2021; [cited 2021, june 26]. available from: https://www.bls.gov/ooh/healthcare/orthotistsand-prosthetists.htm 3.lobbying data summary [internet]. 2020; [cited 2020, november 16]. available from: https://www.opensecrets.org/federal-lobbying. 4.geil m. assessing the state of clinically applicable research for evidence based practice in prosthetics and orthotics. j rehabil res dev .2009;46(3):305-14. doi:10.1682/jrrd.2008.02.0019 5.hafner bj, sawers ab. issues affecting the level of prosthetics research evidence: secondary analysis of a systematic review. prosthet orthot int. 2016; 40(1):31-43. doi:10.1177/ 0309364614550264 6.stevens pm. barriers to the implementation of evidence-based practice in orthotics and prosthetics. j prosthet orthot. 2011; 23(1): 34-9. doi: 10.1097/jpo.0b013e3182064d29 7.newman d, barrette e, mcgraves-lloyd k. medicare competitive bidding program realized price savings for durable medical equipment purchases. health aff. 2017; 36(8):1367-75. doi: 10.1377/hlthaff.2016.1323 8.samuelson l. game theory in economics and beyond. j econ perspect. 2016; 30(4):107-30. doi: 10.1257/jep.30.4.107 9.inman p. us game theory specialists win nobel prize in economics. the guardian [internet]. 2021; [cited 2021, june 26]. available from: https://www.theguardian.com/science/2020/oct/12/us-gametheory-specialists-win-nobel-prize-in-economics 10.axelrod r. effective choice in the prisoner's dilemma. j conflict resolut. 1980; 24(1):3-25. doi: 10.1177/002200278002400101 11.nicholson w. intermediate microeconomics and its application. 9th edition. thomson/south-western publishing co. 2004. https://www.cengage.com/economics/discipline_content/preview_ guide/preview_guide/previewguide_nicholsonsnyder_11e.pdf 12.fuenzalida squella sa, kannenberg a, brandão benetti â. enhancement of a prosthetic knee with a microprocessor-controlled gait phase switch reduces falls and improves balance confidence and gait speed in community ambulators with unilateral transfemoral amputation. prosthet orthot int. 2018; 42(2):228-35. doi:10.1177%2f0309364617716207 13.kaufman kr, levine ja, brey r, iverson b, mccrady s, padgett d, et al. gait and balance of transfemoral amputees using passive mechanical and microprocessor-controlled prosthetic knees. gait posture. 2007; 26(4):489-93. doi:10.1016/j.gaitpost.2007.07.011 https://doi.org/10.33137/cpoj.v4i2.36661 https://www.bls.gov/ooh/healthcare/orthotists-and-prosthetists.htm https://www.bls.gov/ooh/healthcare/orthotists-and-prosthetists.htm https://www.opensecrets.org/federal-lobbying https://www.theguardian.com/science/2020/oct/12/us-game-theory-specialists-win-nobel-prize-in-economics https://www.theguardian.com/science/2020/oct/12/us-game-theory-specialists-win-nobel-prize-in-economics https://www.cengage.com/economics/discipline_content/preview_guide/preview_guide/previewguide_nicholsonsnyder_11e.pdf https://www.cengage.com/economics/discipline_content/preview_guide/preview_guide/previewguide_nicholsonsnyder_11e.pdf 4 fiedler g, schikorra a. a brief introduction to game theory and its potential implications for the economics of orthotics & prosthetics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.18. https://doi.org/10.33137/cpoj.v4i2.36661 issn: 2561-987x a brief introduction to game theory in p&o fiedler & schikorra, 2021 cpoj special s p e c ia l i s s u e 14.ouenniche j, boukouras a, rajabi m. an ordinal game theory approach to the analysis and selection of partners in public–private partnership projects. j optim theory appl. 2016; 169(1):314-43. doi:10.1007/s10957-015-0844-3 authors scientific biography goeran fiedler is an assistant professor with the pitt mspo program. a clinical prosthetist/orthotist by training, he obtained additional graduate degrees in clinical engineering at the university of applied sciences giessen (germany) and in health sciences at the university of wisconsin-milwaukee, as well as post-doctoral training in prosthetics at the university of washington in seattle. his research interests include the improvement of outcomes in lower limb prosthetics by optimizing prescription, fitting, and alignment of devices. armin schikorra holds graduate degrees in mathematics from rwth aachen and university of freiburg (both in germany) and has completed postdoctoral training at eth zurich, university of basel (both in switzerland) and max-planck institute leipzig (germany). as of 2021, he serves as associate professor at the university of pittsburgh’s department of mathematics. his research focuses on geometric analysis, harmonic analysis, and nonlinear partial differential equations. https://doi.org/10.33137/cpoj.v4i2.36661 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 1 2020 literature review brunelli s, bonanni c, foti c, traballesi m. a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a transtibial amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.3. https://doi.org/10.33137/cpoj.v3i1.33640 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://doi.org/10.33137/cpoj.v3i1.33640 1 brunelli s, bonanni c, foti c, traballesi m. a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a trans-tibial amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.3. https://doi.org/10.33137/cpoj.v3i1.33640 literature review a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a trans-tibial amputation brunelli s1*, bonanni c2, foti c2, traballesi m1 1 fondazione santa lucia, scientific institute for research, hospitalization and health care, rome, italy. 2 physical and rehabilitation medicine, tor vergata university of rome, rome, italy. the lower limb amputation is a dramatic event that can negatively impact functional mobility, perceived health status (hs) and quality of life (qol) of a person.1 in the past, qol and hs outcome have not been considered as an important goal for a rehabilitation project. moreover, qol and hs assessments are rarely performed in routine clinical practice and in clinical trials, particularly in the field of prosthetics. the hypothesis that a better functional outcome (i.e. mobility and performance with the prosthesis), is associated with improved qol is not always confirmed, as patients’ perception of overall well-being and satisfaction could be different from the predictions of physicians.2 for a complete and accurate assessment of multiple aspects of a person's status, it is important to differentiate between hs and qol.3 quality of life has been defined by the world health organization (who) as “individuals' perceptions of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns”.4,5 health status is often indistinct from qol. the assessment of perceived open access volume 3, issue 1, article no.3. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: several reviews have been published regarding quality of life (qol) and health status (hs) in persons with lower limb amputation (lla). however, little has been discussed in the literature with respect to older populations (i.e. age>60 years) with trans-tibial amputation. furthermore, the perceived satisfaction with prosthesis is another important aspect for consideration in the amputees’ life. objective: the purpose of this review was to evaluate the impact of trans-tibial amputation on the qol, hs and prosthesis satisfaction, in order to determine the appropriate intervention to improve these aspects in older population of trans-tibial amputees (tta). methods: research articles, published between january 2000 to march 2019, were found using scopus, pubmed and google scholar databases. the methodological quality of the selected articles was assessed using the critical review form-quantitative studies checklist. results: ten articles that met the inclusion criteria were selected. in these papers, we can summarize that people with trans-tibial amputation have a better qol compared to those with above knee amputation. moreover, physical functioning and mobility are the most influencing factors for qol and hs in older people with lower limb amputation. finally, the prosthesis weight reduction may improve satisfaction with the prosthetic limb. conclusion: efforts have to be made in order to improve mobility in older population with transtibial amputation for better qol and hs. this can be accomplished by means of adequate rehabilitation, pain management and an accurate choice of appropriate prosthetic components. we observed that the quality of evidence in the literature available is inadequate and future research would benefit from more prospective observational cohort studies with appropriate inclusion criteria and larger sample sizes to better understand the qol and hs in this population. article info received: february 3, 2020 accepted: may 16, 2020 published: may 21, 2020 citation brunelli s, bonanni c, foti c, traballesi m. a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a trans-tibial amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.3. https://doi.org/10.33137/cpoj. v3i1.33640 keywords quality of life, amputation, satisfaction, rehabilitation, review, prosthesis, amputee, lower limb amputation, health status. * corresponding author: stefano brunelli, md santa lucia foundation, scientific institute for research, hospitalization and health care, rome, italy. e-mail: s.brunelli@hsantalucia.it orcid: https://orcid.org/0000-0002-5986-1564 introduction https://doi.org/10.33137/cpoj.v3i1.33640 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i1.33640 https://doi.org/10.33137/cpoj.v3i1.33640 mailto:s.brunelli@hsantalucia.it https://orcid.org/0000-0002-5986-1564 2 brunelli s, bonanni c, foti c, traballesi m. a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a trans-tibial amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.3. https://doi.org/10.33137/cpoj.v3i1.33640 issn: 2561-987x the evaluation of quality of life, health status and satisfaction with the prosthesis brunelli et al. 2020 cpoj health status has the goal of evaluating a persons’ perception of his or her disease influenced by the complex interactions of social, emotional and physical functioning.6 the evaluation of qol and hs, by means of reliable questionnaires, might determine which are the most influencing factors and thereby helping the rehabilitation team or the healthcare services to improve care of persons with limb amputation.7 a proper investigation of qol in people with amputation could rely on the use of specific instruments developed for this purpose, such as: trinity amputation and prosthesis experience scales (tapes)8 that investigate these domains: psychosocial adjustment; social, functional and athletic restriction; prosthesis satisfaction; pain and other medical problems, or the prosthesis evaluation questionnaire (peq)9 which investigates ambulation, appearance, frustration, perceived response, residual limb health, social burden, sounds, utility and well-being. a comfortable prosthetic device allows amputees to walk and carry out daily activities without pain and could increases their satisfaction, independence and activity level.10 even an aesthetically acceptable prosthetic device might favourably influence the social reintegration of the patient. a comprehensive life assessment of people with lower limb amputation must take into account their satisfaction with the prosthesis. those satisfaction aspects are included in some items of tapes and peq. furthermore, the sat-pro (satisfaction with prosthesis) was developed specifically for this purpose.11 many studies have investigated functional outcome, functional status, mobility level and the predictor factors in lla.12,13 however, rarely those data are associated with qol, hs or satisfaction with the prosthesis. moreover, studies rarely focus on different populations of lla, in a way that the results can be differentiate between elderly or younger people with trans-tibial or trans-femoral amputation.14 it should be noted that poor qol in a person with lower limb amputation may depend not only on physical disability but also on pain, in particular low back pain or artrithis15,16 or phantom pain.17 in addition, traumatic amputation at young age is associated with better qol.18 some reviews about qol and hs are available, however they are related exclusively to a general sample of lla.14,19,20 this literature review was undertaken with a purpose to support or refute any or all of the following assumptions: a) tta have better mobility capacity than tfa21; b) people above 65 years old present lower physical performance than younger patients; and c) the performance status of older patients after amputation is generally poor.22 with these observations in mind, the aim of this review was to analyse the qol, hs and satisfaction with the prosthesis in a specific group of trans-tibial amputees (i.e. age>60y). methodology search strategy two authors, sb and cb, independently conducted a search in the spring 2019 to find related research articles using scopus, pubmed and google scholar databases. the electronic literature search included articles published from january 2000 to march 2019, using the keywords “amputee”, “lower limb amputation”, “trans-tibial”, “belowknee”, “health status,” “quality of life”, “outcome” and “satisfaction”. we have included the keyword “outcome” as sometimes the keyword of a study was the functional outcome and the qol or hs described only as secondary aims. moreover, “sf-36", "who qol-bref", "peq", "ppa (prosthetic profile for amputee23)" and "tapes-r", have also been searched as these are the most used tools for the measurements of qol or hs in lla. combinations of keywords were made in order to refine the search results by using boolean terms ‘and’ and ‘or’. review process the reference lists of all screened articles were also examined for any potentially eligible studies. reviews, case reports, congresses abstracts, comments, editorials, guidelines, letters and studies not in english were excluded. articles that focused on individuals with upper limb amputation or solely on individuals with above knee amputation or on people with mean age<60 were excluded. the authors performed a second screening by reading the full-text of the selected articles, to understand if they could obtain data on qol, hs or satisfaction with the prosthesis based on the following inclusion criteria: 1) persons diagnosed with tta; 2) studies investigating qol and/or hs and/or satisfaction with the prosthesis in persons aged >60 years; 3) use of standardized evaluation measures. as all data was drawn from literature and as such no informed consent or ethical approval was needed for this study. study quality the methodological quality of the selected articles was assessed using the critical review form-quantitative studies checklist.24 the checklist consists of 15 questions pertaining to the quality of reporting, internal validity, external validity, and power of the studies. higher scores representing better quality. most questions were answered as “1” for a yes or “0” for a no. some questions had the option “unable to determine”, these questions were excluded from the checklist.24 results article selection an initial electronic database search obtained 892 articles. an identification of duplicates excluded 616 articles. screening of the title and abstract further excluded 184 https://doi.org/10.33137/cpoj.v3i1.33640 3 brunelli s, bonanni c, foti c, traballesi m. a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a trans-tibial amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.3. https://doi.org/10.33137/cpoj.v3i1.33640 issn: 2561-987x the evaluation of quality of life, health status and satisfaction with the prosthesis brunelli et al. 2020 cpoj articles because they were not investigating the impact of a trans-tibial amputation on the qol, hs or satisfaction with the prosthetic limb. eighty-two articles were removed after reviewing the full texts. in total, 10 articles were selected for the purpose of this literature review (figure 1). in our review of literature, no randomized controlled trial studies were found on the topic of interest. the majority were observational studies (n=5) and cross-sectional (n=3) studies while the others were cross-over (n=1) or retrospective studies (n=1). the results of the four studies,2, 25-27 which evaluated qol in older tta are summarized in table 1. four studies17,28-30 evaluated hs in this population and their findings were summarized in table 2 . moreover, table 3 shows two studies on patient level of satisfaction with the prosthesis.31-32 the only study that investigated both hs and qol,27 is included in table 1, as the main results were related to qol. table 1: overview of studies reporting qol data. authors evaluation tools study protocol characteristics of patients aim of study results critical review form total items harness et al. (2001)2 peq follow up 60 dysvascular tta (mean age 65.9 ± 1.4 years) with successful use of current prosthesis for a minimum of 6 months determining qol of a population of tta who were successful prosthetic users the response to the peq domains of perceived responses, frustration, social burden, overall well-being and overall satisfaction were above 65% of the midline of the peq scores. the domains “ambulation” and “transfer” showed less favorable responses. statistical study of the relationships between domains showed these correlations: a. “residual limb health” and “prosthetic appearance” with “social burden” “satisfaction” b. less “pain” with “satisfaction”. c. “ability to ambulate” with “satisfaction” d. “transfer ability” with “satisfaction” and with decreased “social burden” e. “pain” and “residual limb health” with “ability to ambulate” f. “social burden” with “ambulation” 10/12* norvell et al.(2011)25 swls prospective cohort study 87 lla (8 tfa, 52 tta, and 27 transmetatarsal amputees). tta mean age was 61.5±9.1 years. only 43 individuals reached 12-month follow-up examining the association of “mobility success” with satisfaction with mobility and satisfaction with life; comparing rates of mobility success between various amputation levels; evaluating factors associated with mobility success this study did not find a significant difference in mobility results between tfa and tta. this could depend on the very small number of tfa. 50% of tta were satisfied with their mobility. no differences were found between tta and transmetatarsal amputees in terms of mobility satisfaction. the satisfaction with life was 28% higher in amputees with higher mobility score. there is also a correlation between higher mobility score and satisfaction with mobility 14/15 cox et al. (2011)26 who qolbref observational study 87 lla (64 tta, 23 tfa ) mean age: 62±9.9 years. 35 males and 52 females. all tta males were > 60 years. 78% of tta females were >60 years determining the qol of diabetic lla and the relationship with gender, age and amputation level tta showed a better qol. females were found to have higher scores in the qol domains (physical health, physiological, social relationship and environment) than males, even if 40% had a transfemoral amputation. this might depend on the younger age of the females. females across the age groups had a significantly higher qol average scores than males 14/15 quigley et al.(2016)27 tapes-r and modified version of sf-36 (v2) 33 crosssectional study 33 lla (23 tta (mean age 68±10 years), 10 partial foot amputees (63 ± 10 years) comparing qol in people with partial foot amputation secondary to peripheral vascular disease and determining factors influencing qol the statistic analysis showed no significant differences in the sf-36v2 between tta and partial foot amputation. age was the only variable, which concurred significantly with qol, while level of amputation did not 14/15 abbreviations: lla, lower limb amputees; tta, transtibial amputees; tfa, transfemoral amputees; who qol-bref, world health organization quality of life scale; qol, quality of life;; peq, prosthesis evaluation questionnaire; sf-36, short-form general health survey; swls, satisfaction with life scale; tapes-r, trinity amputation and prosthesis experience scale-revised. * some questions had the option “unable to determine”. these questions were excluded from the checklist and this was the reason why some of selected studies might have a maximum score of less than 15. records identified through database searching (n = 892) s c re e n in g in c lu d e d e lig ib ili ty id e n ti fi c a ti o n duplicates records removed (n = 616) records screened (n = 276) records excluded by title and abstract (n = 184) full-text articles assessed for eligibility (n = 92) full-text articles excluded, with reasons: 1) not possible to differentiate tta from tfa (n = 39); 2) not possible to differentiate tta >60y from younger (n = 30); 3) irrelevant (n 13) studies included in qualitative synthesis (n = 10) figure1: flowchart summarizing the study selection process. https://doi.org/10.33137/cpoj.v3i1.33640 4 brunelli s, bonanni c, foti c, traballesi m. a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a trans-tibial amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.3. https://doi.org/10.33137/cpoj.v3i1.33640 issn: 2561-987x the evaluation of quality of life, health status and satisfaction with the prosthesis brunelli et al. 2020 cpoj patients characteristics only three studies focused on tta with a mean age>60 years, two of which primarily investigated the effects of a new prosthetic foot.31,32 only one study exclusively assessed the qol of a population of non-traumatic tta who were successful prosthetic users.2 in most of the selected studies, the sample consisted in a mixed group of tta and tfa. in two articles25,27 the sample also included partial foot amputees and in two other studies28,30 there was a control group consisting of people with intact lower extremities or foot ulcer. qol and hs measurement the most used tools were the research and development corporation measure of quality of life 36-item health authors evaluation tools study protocol characteristics of patients aim of study results critical review form total items van der schans et al.(2002)17 rand-36 crosssectional study 437 lla, 62% tta. 71% males. mean age 65±15 years (8% of the sample was older than 75 years) describing health-related quality of life in lla and investigating potential determinants: including phantom pain age, sex, level of amputation, amputation reason, phantom or stump pain and walking distance health-related quality of life was positively influenced by a) absence of phantom pain, b) walking distance c) absence of stump pain d) amputation through or above the knee 12/13 boutoille et al.(2008)28 mos sf36 retrospective case control study 6 tta (mean age 68 years) and 9 with a current foot ulcer, (mean age 70 years) evaluating the influence of amputation or conservative treatment for a diabetic foot ulcer on physical and social aspects of patients' qol tta group reported less pain but similar qol compared to foot ulcer patients 14/15 fortington et al. (2013)29 rand-36 longitudinal study. 82 lla. mean age 67.8±13 years. 63% tta and 37% tfa. a total of 35 remained in the study at 18 months follow up. evaluating how the age and walking distance could influence qol 18 months after the amputation. comparing qol of lla with a control group only the domain “social function” was influenced significantly by the ability to walk. except for physical function, the other domains were similar to population norm values. the domain “physical function” was positively correlated to lower levels of amputation and to age categories of less than 65 years. qol improved after amputation, in particular in the first 6 months 14/15 knezevic et al. (2015)30 rand36 crosssectional study 28 lla. 61% tfa, 39% tta. mean age: 65.4 ± 13.6 years. assessing the qol of the patients with lla compared to a control group, taking into account the influence of age and level of amputation tta are more mobile than tfa. the most significant difference was in the domains "physical functioning" and "general health", with higher scores reported by tta 14/15 abbreviations: lla, lower limb amputees; tta, transtibial amputees; rand-36, research and development corporation measure of quality of life 36-item health survey 1.0 ; sf-36, short-form general health survey; mos sf-36, medical outcomes study 36-item short-form authors evaluation tools study protocol characteristics of patients aim of study results critical review form total items bonnet et al.(2015)31 quebec user evaluation of satisfaction with assistive technology 2.0 questionnaire crossover study 12 dysvascular tta, mean age 77 years evaluating the benefit of a ngf versus sach foot for low-activity tta higher satisfaction level using ngf compared to sach. the increase is significant for the global score of the questionnaire. 14/15 delussu et al. (2016)32 satpro observational study 20 tta, mean age 66.6±6.7 years. 19 amputees had a klevel of 2 and 1 had a k-level of 1 assessing amputees satisfaction with prosthesis using two different prosthetic feet: 1m10 adjust and sach in low-mobility tta participants showed a significantly higher improvement in sat-pro with “1m10 adjust” than with sach. 12/13 abbreviations: tta: trans-tibial amputee, sat-pro: satisfaction with prosthesis, sach: solid ankle cushion heel, ngf: new geriatric foot. table 2: overview of studies reporting hs data. . table 3: overview of studies reporting satisfaction with the prosthesis data. https://doi.org/10.33137/cpoj.v3i1.33640 5 brunelli s, bonanni c, foti c, traballesi m. a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a trans-tibial amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.3. https://doi.org/10.33137/cpoj.v3i1.33640 issn: 2561-987x the evaluation of quality of life, health status and satisfaction with the prosthesis brunelli et al. 2020 cpoj survey 1.0 (rand36) (3 times) and the sf-36 (2 times).34,35 the rand-36 is a self-reported questionnaire which includes the same items as those of sf-36, but scoring is slightly different in the domains "pain" and "general health". peq and tapes-r questionnaire was used one time (table 4). table 4: overview of the tools used for hs and qol. evaluation tools authors peq harness et al (2001)2 swls norvell et al (2011)25 who qol-bref cox et al (2011) 26 tapes-r quigley et al (2016)27 sf-36 quigley et al (2016)27;boutoille et al (2008)28; knezevic et al (2015)30 rand-36 van der schans et al (2002)17;knezevic et al (2015)30; fortington et al (2013)29 discussion the intention of this review was to evaluate the impact of trans-tibial amputation on the qol, hs and prosthesis satisfaction, in order to determine the appropriate intervention to improve these aspects in older trans-tibial amputees. many studies reported a better qol and hs in tta compared to tfa,26 particularly in the “physical functioning” domain.29,30 moreover, tta also had significantly higher scores for functional independence compared to the tfa.26 considering that tta have better qol than tfa, we investigated whether these patients could maintain high qol throughout the aging process. indeed, young age at the time of amputation was associated with better qol in the categories of physical disability, energy level, emotional reactions and social isolation while advanced age was associated with reduced mobility and lower energy level than younger population.6 however, whether ageing affected qol is still debated. a recent study stated that quality of life in lla is significantly influenced by age,36 while adegoke and co-workers (2012) reported that the patient’ age at the time of amputation did not affect general quality of life.37 in our review, we found that there are no longitudinal studies that describe changes in the quality of life during ageing. the “physical functioning” appears to be the main factor affecting qol and satisfaction in older tta. indeed, fortington et al., (2013) found that subjects over 65 years of age had lower outcome than younger amputees only for physical function, while other domains were comparable to population norm values.29 the walking distance aspect of mobility is one of the main factors to be considered when evaluating qol after lla.17 elderly tta with higher mobility scores were more likely to be satisfied with life,25 and perception of their social burden correlated strongly with their ability to walk using their prosthesis. fortington et al.,29 reported that walking distance is associated with improved scores in social function. one study identified also that mobility capability was significantly influenced by these risk factors: age>65y, alcohol disorder, hypertension, anxiety or depression.25 another aspect that was postulated to interfere with qol was the level of pain. rather controversially the results did not confirm this assumption. in fact, in the only study in which tta alone were enrolled, harness et al., (2001)2 found that the ability to walk using the prosthesis was correlated with the presence of pain and residual limb health.2 moreover, the same study reported a correlation between the patient’s satisfaction and lesser pain level.2 even knežević and co-workers reported no differences between tta and tfa on role limitations due to pain and physical health.30 on the contrary, another study described how the presence of phantom pain might imply a poorer health-related quality of life.17 an important role of pain was described by boutoille et al.,(2008).28 the authors compared hs and pain in patients having experienced an amputation due to diabetic foot ulcer and patients suffering for a current foot ulcer with no previous history of amputation. they reported that a transtibial amputation allows similar hs with less pain with respect to a conservative, unsuccessful, treatment for diabetic ulcer. two studies focused on the effect of a prosthetic foot in hypomobile older tta.31,32 both studies investigated the performance and satisfaction utilizing different feet compared to the traditional sach (solid ankle cushion heel) foot. the sach is considered to be the most appropriate foot for hypomobile tta and also the most prescribed foot as it is inexpensive, easy to use, and perceived as stable.39 delussu et al.,(2016) tested the “1m10 adjust” foot that is a multi-axial lightweight foot that allows stiffness heel adjustments to adapt to individual needs.32 in another study a new geriatric foot was evaluated which shape and type of foam in this foot allows to be shorter and lighter compared to sach.31 both studies reported greater patient satisfaction with the tested prosthetic feet. moreover, the new geriatric foot reduced the mean pressure in the socket and the “1m10 adjust” showed a statistically significant reduction of the energy cost of walking.31,32 the common feature between these two tested prosthetic feet is the lighter weight compared to sach. this may lead us to hypothesize that lighter prosthetic components for hypomobile mature tta could positively affect their satisfaction with the prosthesis. in this review we selected only articles published from january 2000 to march 2019 which might be a limitation. https://doi.org/10.33137/cpoj.v3i1.33640 6 brunelli s, bonanni c, foti c, traballesi m. a literature review of the quality of life, health status and prosthesis satisfaction in older patients with a trans-tibial amputation. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.3. https://doi.org/10.33137/cpoj.v3i1.33640 issn: 2561-987x the evaluation of quality of life, health status and satisfaction with the prosthesis brunelli et al. 2020 cpoj we did not search studies prior to 2000 because of the important progress in technology of the socket and suspension system in the late 1990s (from patellar tendon bearing to total surface bearing). conclusion our review has pointed out that there are very few studies that have investigated this particular population of amputees (tta aged >60 years). only one study exclusively investigated qol in older tta.2 we have observed authors have rarely used specific tools for measurement of qol and hs in lla. in general, the qol and hs of lla is influenced mostly by daily activities.40 patients with amputation often encounter difficulties in everyday activities because they have lost their independence and must rely on others. this could influence negatively many aspects of their lives, such as social and financial. for this, it is very important, when studying qol of amputees, to also analyse their social environment.41 on the basis of the main results of this review we can conclude that efforts have to be taken in order to improve mobility in tta for a better qol, by means of adequate rehabilitation, reduction of pain, and appropriate prosthetic components. the literature available on this specific population is insufficient and future research will benefit from more prospective observational cohort studies. such studies will need to be conducted with appropriate inclusion criteria and larger sample sizes to better understand the qol and hs in this population. declaration of conflicting interests the authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. author contribution stefano brunelli: designed the study, online databases search and led the writing of the manuscript. cinzia bonanni: online databases search, data extraction and supported the writing of the manuscript. calogero foti: revised the manuscript critically for important intellectual content. marco traballesi: revised the manuscript critically for important intellectual content. sources of support the authors received no financial support for the research, authorship, and/or publication of this article. abbreviations qol: quality of life, hs: health status, lla: lower limb amputee, tta: trans-tibial amputee, tfa: trans-femoral amputee, tapes: trinity amputation and prosthesis experience scales, peq: prosthesis evaluation questionnaire, who qolbref: world health organization quality of life questionnaire, sf-36: the 36-item short form health survey, nhp: nottingham health profile, rand36: research and development corporation measure of quality of life 36-item health survey 1.0, sat-pro: satisfaction with prosthesis, ngf: new geriatric foot, swls: satisfaction with life scale. references 1.pernot hf, winnubst gm, cluitmans jj, de witte lp. amputees in limburg: incidence, morbidity and mortality, prosthetic supply, care utilisation and functional level after one year. prosthet orthot int. 2000;24:90-6. doi:10.1080/03093640008726531 2.harness n, pinzur ms. health related quality of life in patients with dysvascular transtibial amputation. 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arch phys med rehabil. 1994;75:1309-14. doi:10.1016/0003-9993(94)90278-x 24.law m, stewart d, pollock n, letts l, bosch j, westmorland m. guidelines for critical review form—quantitative studies. mcmaster university. 1998. available at: https://srs-mcmaster. ca/wp-content/uploads/2015/05/guidelines-for-critical-reviewform-quantitative-studies. pdf. accessed may 19, 2020 25.norvell dc, turner ap, williams rm, hakimi kn, czerniecki jm. defining successful mobility after lower extremity amputation for complications of peripheral vascular disease and diabetes. j vasc surg. 2011;54:412-9. doi:10.1016/j.jvs.2011.01.046 26.cox ps, williams sk, weaver sr. life after lower extremity amputation in diabetics. west indian med j. 2011;60(5):536-40 27.quigley m, dillon mp, duke ej. comparison of quality of life in people with partial foot and transtibial amputation: a pilot study. prosthet orthot int. 2016;40:467-74. doi: 10.1177/ 0309364614568414 28.boutoille d, féraille a, maulaz d, krempf m. quality of life with diabetes-associated foot complications: comparison between lower-limb amputation and chronic foot ulceration. foot ankle int. 2008;29:1074-8. doi:10.3113/fai.2008.1074 29.fortington lv, dijkstra pu, bosmans jc, post wj, geertzen jh. change in health-related quality of life in the first 18 months after lower limb amputation: a prospective, longitudinal study. j rehabil med. 2013;45(6):587-94. doi:10.2340/16501977-1146 30.knezevic a, salamon t, milankov m, ninkovic s, jeremicknezevic m, tomasevic-todorovic s. assessment of quality of life in patients after lower limb amputation. med pregl. 2015;68(34):103-8. doi:10.2298/mpns1504103k 31.bonnet x, adde jn, blanchard f, gedouin-toquet a, eveno d. evaluation of a new geriatric foot versus the solid ankle cushion heel foot for low-activity amputees. prosthet orthot int. 2015;39(2):112-8. doi:10.1177/0309364613515492 32.delussu, a. s., paradisi, f., brunelli, s., pellegrini, r., zenardi, d., traballesi, m. comparison between sach foot and a new multiaxial prosthetic foot during walking in hypomobile transtibial amputees: physiological responses and functional assessment. eur j phys rehabil med. 2016;52(3),304-309 33.maruish mee. user’s manual for the sf-36 v2 health survey. 3rd ed. lincoln, ri: qualitymetric incorporated, 2011 34.ware le & sherbourne cd (1992). the mos 36-item shortform health survey (sf-36): i. conceptual framework and item selection. medical care. 1992;30(6):473-83 35.hays rd, sherbourne cd, mazel rm. the rand 36-item health survey 1.0. health econ. 1993;2(3):217-27 36.mohammed sa, shebl am. quality of life among egyptian patients with upper and lower limb amputation. sex differences. adv. med. 2014;2014:674323. doi:10.1155/2014/674323 37.adegoke boa, kehinde ao, akosile co, oyeyemi al. quality of life of nigerians with unilateral lower limb amputation. disability, cbr and inclusive development. 2012;23(4):76–89. doi: 10.5463/dcid.v23i4.192 38.hays rd, morales ls. the rand-36 measure of health related quality of life. ann med. 2001;33:350-357. doi: 10.3109/07853890109002089 39.andrews kl. rehabilitation in limb deficiency, 3: the geriatric amputee. arch phys med rehabil. 1996;77:s14-7. doi: 10.1016/s0003-9993(96)90238-5 40.weiss, gn, gorton, a, read, rc, neal, la. outcomes of lower extremity amputations. j am ger soc. 1990;38:877-883. doi: 10.1111/j.1532-5415.1990.tb05703.x 41.gitter a, bosker g. upper and lower extremity prosthetics. in: delisa j, editor. physical medicine & rehabilitation: principles and practice. philadelphia: lippincott williams & wilkins; 2005;1326-55 https://doi.org/10.33137/cpoj.v3i1.33640 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 6, issue 1 2023 research article bajracharya ar, seng-iad s, sasaki k, guerra g. cross-cultural adaptation and validation of the nepali version of the prosthetic limb users survey of mobility short-form (plus-m™/nepali-12sf) in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.1. https://doi.org/10.33137/cpoj.v6i1.41310 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v6i1.41310 1 bajracharya ar, seng-iad s, sasaki k, guerra g. cross-cultural adaptation and validation of the nepali version of the prosthetic limb users survey of mobility short-form (plus-m™/nepali-12sf) in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.1. https://doi.org/10.33137/cpoj.v6i1.41310 research article cross-cultural adaptation and validation of the nepali version of the prosthetic limb users survey of mobility short-form (plus-m™/nepali12sf) in lower limb prosthesis users bajracharya ar1, seng-iad s1 *, sasaki k1, guerra g2 1 sirindhorn school of prosthetics and orthotics, faculty of medicine siriraj hospital, mahidol university, bangkok, 10700, thailand. 2 department of exercise and sport science, st. mary’s university, san antonio, texas, 78210, usa. introduction recent data from the who-unicef global report on assistive technology (great) estimates that approximately 2.5 million people are in need of assistive technologies now, and by 2050 that number will rise to 3.5 million people.1 moreover, for persons residing in resource limited settings, only 3% may have access to vital assistive technologies. several key recommendations have been provided in the great report, one of which is to ensure effectiveness of assistive technology (at) and actively involve at users in this process. lower limb prosthetics are an essential at for persons with limb loss disabilities. the effectiveness of rehabilitation treatment must be assessed using reliable performance based and patient reported outcome measures.2 a plethora of instruments have been developed to better understand the effect of prosthetic treatment on mobility.3–5 the prosthetic limb users survey of mobility (plus-m™) is a recently developed instrument for measuring lower limb prosthesis user mobility.6 this instrument was developed following rigorous patient reported outcome measurement procedures.7 the plusm™ has good construct validity with amputee mobility predictor (amp)4 and timed up and go test (tug).8 the amp provides clinicians a tool for determining prosthesis user activity level. the two-minute walk test (2mwt) also offers indices of prosthesis user walking capacity in a short open access abstract background: objective mobility measurement of nepali prosthesis users is lacking. objective: the objective of this study was to cross-culturally adapt, translate and evaluate construct validity of the prosthetic limb users survey of mobility (plus-m™/nepali-12 short form (sf)) instrument in lower limb prosthesis users residing in nepal. methodology: two forward translations, review and reconciliation, back translation, expert review, developer review to create the plus-m™/nepali-12sf. psychometric testing for internal consistency, test-retest reliability and construct validity against the two-minute walk test (2mwt) and amputee mobility predictor with prosthesis (amppro) were performed on sixty-six lower limb prosthesis users. findings: the majority of populations were with transtibial amputation 45 (68%), with transfemoral amputation 15 (23%), with knee disarticulation 5 (7.5%) and with syme’s amputation 1 (1.5%). the most common cause of amputation among the population was trauma and the least was tumor. chronbach’s alpha for the plus-m™/nepali-12sf was 0.90, mean t-score was 52.90, test-retest intraclass correlation coefficient (icc) was 0.94 (95% confidence interval 0.90-0.96). construct validity with the 2mwt was good (r = 0.62, p< 0.001) and moderately positive with the amppro (r = 0.57, p< 0.001). conclusion: our research evidenced that the plus-m™/nepali -12sf had excellent reproducibility. the significance of this work is that it may allow for the measurement of mobility in austere locations of nepal. article info received: june 27, 2023 accepted: august 12, 2023 published: august 23, 2023 citation bajracharya ar, seng-iad s, sasaki k, guerra g. cross-cultural adaptation and validation of the nepali version of the prosthetic limb users survey of mobility short-form (plus-m™/nepali12sf) in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.1. https://doi.org/10.33137/cpoj.v6i1.4 1310 keywords prosthetics, plus-m, 2mwt, outcome measurement, survey, mobility, nepali, lower limb prosthesis. * corresponding author: sirirat-seng-iad, sirindhorn school of prosthetics and orthotics, faculty of medicine, siriraj hospital, mahidol university, bangkok, thailand. email: sirirat.sen@mahidol.edu orcid id: https://orcid.org/0009-0008-7187-3593 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 1, article no.1. 2023 https://doi.org/10.33137/cpoj.v6i1.41310 https://doi.org/10.33137/cpoj.v6i1.41310 https://doi.org/10.33137/cpoj.v6i1.41310 mailto:sirirat.sen@mahidol.edu https://orcid.org/0009-0008-7187-3593 https://jps.library.utoronto.ca/index.php/cpoj/index 2 bajracharya ar, seng-iad s, sasaki k, guerra g. cross-cultural adaptation and validation of the nepali version of the prosthetic limb users survey of mobility short-form (plus-m™/nepali-12sf) in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.1. https://doi.org/10.33137/cpoj.v6i1.41310 canadian prosthetics & orthotics journal issn: 2561-987x plus-m™/nepali-12sf bajracharya et al., 2023 and simple to administer assessment.9 these two assessments combined offer a practical means for gauging mobility in lower limb prosthesis users.10,11 in the event that a performance based mobility measurement cannot take place, the plus-m™ may serve well. correlation between plus-m™ and mobility measures has previously indicated convergent construct validity.6 understanding how well a prosthesis user can walk over the varied and sloped terrain in nepal is important for the nepali prosthetists. nepali prosthesis users must ambulate in these harsh terrains for work, activities of daily living and leisure.12 although the plus-m™ is available in many languages,13,14 it has yet to be translated and culturally adapted to nepali. the objective of this study was to crossculturally adapt, translate and evaluate construct validity of the plus-m™/nepali-12 short form (sf) instrument in lower limb prosthesis users residing in nepal. methodology setting this study was approved by siriraj institutional review board and also by nepal health research council. all participants provided written informed consent prior to data collection. sixty-six lower limb prosthetic user’s age 18 who were independent and had received their prosthesis for at least six months were purposively selected from regional centers. these users had no neurological, musculoskeletal or pathologies which would have affected study participation. participants unable to understand nepali; users needing assistance of helper to walk, cognition problem, users with underlying medical conditions affecting mobility and <18 years of age were excluded from this study. cross-cultural translation permission to proceed with translation was received from the instrument developer and a formal translation method was performed. the developers provided pertinent scoring and definition guides for instrument items. two bilingual nepal and english persons (physical therapist, prosthetist) independently established a nepali version. next, bilingual experts (medical doctor, physical therapist) reviewed possible discrepancies. thereafter, a reconciled version was created and back translated by an american who speaks nepali. this backward translation was sent to the developer; professor brian hafner to review and incorporate or change if needed. the comments and suggestions from developer were incorporated in nepali version by translator and revised back translation was again sent to the developer for additional feedback. the comments and suggestion were collected and incorporated in revised back translation and this version was provided to three independent bilingual experts (medical doctor, physical and occupational therapist). this revised addition was modified for precision before being sent to the developer for a final review. the final plus-m™/nepali 44 items bank was pre-tested by cognitive interview with 7 participants with lower limb amputation, which helped to detect respondent interpretation. concurrent probing took place in an interview by comparing each item with the help of a manual of definitions of terms and intentions of each question item provided by the developer. psychometric evaluation demographic data, amputation date, level and etiology were recorded. the data collector evaluated performancebased outcome measures two-minute walk test (2mwt)15 and amputee mobility predictor with prosthesis (amppro), and plus-m™ nepali 12 item short form (plus-m™/ nepali-12sf). the participants were given the option of performing the plus-m™ nepali-12sf first, followed by the 2mwt, and amppro, or the 2mwt, and amppro followed by the plus-m™/nepali-12sf. the 2mwt and amppro served as a basis for construct validity testing. in the 2mwt participants were instructed to walk as fast as possible without running along a flat rectangular outdoor walkway of 20 meter (65.6 ft.), and distance was recorded in meters. to explore test-retest reliability participants performed the plus-m™/nepali-12sf once more two weeks later. data analysis spss v16 (ibm, armonk, new york, usa) was used to analyze data. characteristics of the participants were analyzed using a pearson chi square test (p<0.05) and 95% confidence interval. internal consistency was assessed via chronbach’s alpha, with  0.07 considered good internal consistency.16 an intra-class correlation coefficient (icc) was employed to evaluate test-retest reliability. construct validity was evaluated using a pearson correlation coefficient, with r  0.6 = good to excellent and r < 0.6 = poor to moderate correlation.17 results sixty-six prosthesis users completed the study (37.26  11.81 years old) (figure 1). figure 2 provided item and mean responses to the instrument. the overall chronbach’s alpha for the plusm™/nepali-12sf was 0.90 showing good internal consistency. this instrument scores using a t-score which is a standardized score with a mean of 50 and standard deviation of 10. a higher t-score is equal to a higher mobility and vice-versa. plus-m™/nepali-12sf initial mean t-score was 52.90, with standard deviation 5.6. the minimum score was 36.4 and maximum was 67.1. https://doi.org/10.33137/cpoj.v6i1.41310 3 bajracharya ar, seng-iad s, sasaki k, guerra g. cross-cultural adaptation and validation of the nepali version of the prosthetic limb users survey of mobility short-form (plus-m™/nepali-12sf) in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.1. https://doi.org/10.33137/cpoj.v6i1.41310 canadian prosthetics & orthotics journal issn: 2561-987x plus-m™/nepali-12sf bajracharya et al., 2023 good test-retest icc for t-score was seen 0.94 (95% confidence interval 0.90-0.96), with initial t-score being 52.90  5.6 and retest t-score being 52.47  5.6 (figure 3 and figure 4).18 mean distance covered on the 2mwt was 145.45  34.2m and mean amppro score was 40.18  3.8 (k3). construct validity with the 2mwt was good (r = 0.62, p< 0.001) and moderately positive with the amppro (r = 0.57, p< 0.001) (figure 5). figure 1: demographics of study participants (n=66). figure 2: mean participant response on plus-m™/nepali-12sf. note: figure illustrates mean response on items of the instrument. lower number indicates more difficulty performing the task. solid large circle is mean, smaller circles are individual data points. solid lines connect tests and rain cloud plots on the right indicate data distribution. figure 3: mean test and retest t-scores for plus-m™/nepali12sf figure 4: bland-altman plot of plus-m™/nepali-12sf. note: average of test and retest (x-axis) plotted against difference between test and retest (y-axis). limits of agreement are represented as dotted lines. 0 1 2 3 4 5 are you able to walk a short distance in your home? are you able to step up and down curbs? are you able to walk across a parking lot? are you able to walk over gravel surfaces? are you able to move a chair from one room to another? are you able to walk while carrying a shopping basket in one hand? are you able to keep walking when people bump into you? are you able to walk on a unlit street or sidewalk? are you able to keep up with others when walking? are you able to walk across as slipper floor? are you able to walk down a steep gravel driveway? are you able to hike about 2 miles on uneven surfaces including hills? 4.86 4.42 4.20 3.85 4.68 4.50 3.85 3.70 3.62 2.94 3.35 2.70 <25 (16.7%) 25-35 (31.8%) 36-45 (27.3%) 46-55 (16.8%) 56-65 (7.4%) age trauma (66.7%) infection (12.1%) dysvascular (13.6%) tumor (7.6%) cause right tt (33.3%) left tt (34.8%) right tf (10.6%) left tf (12.1%) right kd (4.5%) left kd (2%) symes (1%) level hilly (72.7%) moutainous (6.1%) terai (21.2%)location <25 (16.7%) 25-35 (31.8%) 36-45 (27.3%) 46-55 (16.8%) 56-65 (7.4%) age trauma (66.7%) infection (12.1%) dysvascular (13.6%) tumor (7.6%) cause right tt (33.3%) left tt (34.8%) right tf (10.6%) left tf (12.1%) right kd (4.5%) left kd (2%) symes (1%) level hilly (72.7%) moutainous (6.1%) terai (21.2%)location 30 40 50 60 70 -5 0 5 10 15 average of the two measures d if fe re n c e o f th e t w o m e a s u re s t -s c o re plus-m™/nepali-12sf https://doi.org/10.33137/cpoj.v6i1.41310 4 bajracharya ar, seng-iad s, sasaki k, guerra g. cross-cultural adaptation and validation of the nepali version of the prosthetic limb users survey of mobility short-form (plus-m™/nepali-12sf) in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.1. https://doi.org/10.33137/cpoj.v6i1.41310 canadian prosthetics & orthotics journal issn: 2561-987x plus-m™/nepali-12sf bajracharya et al., 2023 figure 5: correlation between plus-m™/nepali-12sf and reference mobility measures. note: a: plus-m™/nepali-12sf to 2mwt; b: plus-m™/nepali-12sf to amppro. discussion the objective of this study was to cross-culturally adapt, translate and evaluate the construct validity of the plusm™/nepali-12 sf in lower limb prosthesis users residing in nepal. cross-cultural and linguistic translation achieved high internal consistency and t-scores of this study were similar to those seen in the developmental plus-m™ study, 52.90 compared to 50.6 our participants still fell within 1 standard deviation of average mobility of over 1,000 lower limb prosthesis users.19 still, our t-scores were lower than that seen in the french speaking population 56.1.13 regardless, t-scores indicated that our sample were highly capable of ambulation in their respective environments. our test-retest findings were excellent and similar to that seen in both the french and original developmental study. good construct validity was seen with the 2mwt. the 2mwt was an appropriate choice for comparison to the plus-m™ as it asks the user to walk at their maximum mobility potential.20 correlation with the amppro was r = 0.57 and compared favorably with that of the original study r = 0.54. participant performance in our study evidenced a high mobility and activity level as demonstrated by the amppro, 2mwt and plus-m™/nepali-12sf scores. this may be a result of the younger age, trauma amputation, or trans-tibial level of amputation. as trans-tibial prosthesis users generally have greater mobility and reduced energy expenditure than higher level amputees.21,22 plus-m™ scores for dysvascular amputees has been reported as 45.3  2.4 which is much lower than our sample but still within 1 standard deviation of mobility of lower limb prosthesis users. our participants walked on average 145m during the 2mwt which is much lower than able-bodied persons (183200m),23 but very similar to that of trans-tibial users (147.02 ± 25.9).24 distances covered are a reflection of walking speed, which in our study was 72.5 m/min. others have observed speeds of 82.3 m/min for trans-tibial and 61.7 m/min for transfemoral users during the 2mwt.25 the amputee mobility predictor (amp) is a popular outcome measure that many clinicians use to categorize amputee activity potential.26 k-level classification is a commonly used system to classify the functional level of persons with lower limb amputation based on their mobility and ability for potential prosthetic use. the k-level classification system indicates a level of functional ability and mobility which commonly ranges from k0non ambulatory to k4highly active. in the present study, we saw most of our participants being categorized as k3 level ambulators. although in the united states, k-level greatly influences prosthetic prescription and resources, it plays little precedent in nepali health policy. limitations this study is not without its limitations. although we recruited a large sample of lower limb amputees, most lost their limbs as a result of trauma which is not a generalization of typical amputation causes. there are reports that nearly 93.4% of amputations are caused by dysvascular reasons.27 moreover, nepal experienced a major earthquake in the last decade and road traffic trauma is one startling cause of amputation in the region.28 taken together, these two factors may have influenced the sample we relied on for this study. although it may seem useful to use the plus-m™ as a prosthetic outcome measure for new patients, it is recommended to prolong administration until users are accommodated. however, recent scholarship has revealed no worsening or improvement in plus-m™ scores from 1 to 7 year.29 conclusion in this study, we performed cultural contextual translation of a widely used prosthetic mobility outcome measure. our research evidenced that the plus-m™/nepali-12sf that 30 40 50 60 70 0 50 100 150 200 250 plus-m/nepali-12sf 2 m w t r = 0.62 a 30 40 50 60 70 0 10 20 30 40 50 plus-m/nepali-12sf a m p ro r = 0.57 b 30 40 50 60 70 0 50 100 150 200 250 plus-m/nepali-12sf 2 m w t r = 0.62 a 30 40 50 60 70 0 10 20 30 40 50 plus-m/nepali-12sf a m p ro r = 0.57 b plus-m™/nepali-12sf plus-m™/nepali-12sf a m p p r o https://doi.org/10.33137/cpoj.v6i1.41310 5 bajracharya ar, seng-iad s, sasaki k, guerra g. cross-cultural adaptation and validation of the nepali version of the prosthetic limb users survey of mobility short-form (plus-m™/nepali-12sf) in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.1. https://doi.org/10.33137/cpoj.v6i1.41310 canadian prosthetics & orthotics journal issn: 2561-987x plus-m™/nepali-12sf bajracharya et al., 2023 had excellent reproducibility, meeting standards set forth by the instrument developer for individual comparisons. the significance of this work is that it may allow for the measurement of mobility in austere locations of nepal. furthermore, the instrument can be added to performancebased outcome measures to create a broader battery of outcome measures used to understand a prosthesis user’s mobility. the plus-m™/nepali-12sf is currently available for use on the plus-m™ website for download and use by clinicians (https://plus-m.org/translations.html). it is hoped that clinicians residing in nepal can begin to monitor lower limb prosthesis user mobility in an objective, reliable way and simple manner. acknowledgements the authors would like to acknowledge the participants and partnering clinics for their support with this research. this research was supported by the graduate scholarship for international students from neighbouring countries, faculty of medicine siriraj hospital, mahidol university. declaration of conflicting interests the authors declare no conflicts of commercial or financial interest in this research. authors contribution amit ratna bajracharya: writing (original drafting) sirirat seng-iad, kazuhiko sasaki, and gary guerra: conceptualization, writing. all authors have read and agreed to this published version of the manuscript. sources of support this research received no financial support. ethical approval this study was approved by siriraj institutional review board and also by nepal health research council. all participants provided written informed consent prior to data collection. references 1.world health organization & united nations children's fund (unicef). global report on assistive technology [internet]. world health organization,2022; [cited: 2023 june 27]. available from: https://apps.who.int/iris/handle/10665/354357 2.unsworth ca. evidence-based practice depends on the routine use of outcome measures. br j occup ther. 2011; 74: 209–209. doi:10.4276/030802211x13046730116371 3.heinemann aw, bode rk, o’reilly c. development and measurement properties of the orthotics and prosthetics users’ survey (opus): a comprehensive set of clinical outcome instruments. prosthet orthot int. 2003; 27: 191–206. doi: 10.1080/03093640308726682 4.gailey rs, roach ke, applegate eb, cho b, cunniffe b, licht s, et al. the amputee mobility predictor: an instrument to assess determinants of the lower-limb amputee’s ability to ambulate. arch phys med rehabil. 2002; 83: 613–27. doi: 10.1053/apmr.2002. 32309 5.heinemann aw, connelly l, ehrlich-jones l, fatone s. outcome instruments for prosthetics. phys med rehabil clin n am. 2014; 25: 179–198. doi: 10.1016/j.pmr.2013.09.002 6.hafner bj, gaunaurd ia, morgan sj, amtmann d, salem r, gailey rs. construct validity of the prosthetic limb users survey of mobility (plus-m) in adults with lower limb amputation. arch phys med rehabil. 2017; 98: 277–285. doi: 10.1016/j.apmr. 2016.07.026 7.reeve bb, hays rd, bjorner jb, cook kf, crane pk, teresi ja, et al. psychometric evaluation and calibration of health-related quality of life item banks: plans for the patient-reported outcomes measurement information system (promis). med care. 2007; 45: s22–s31. doi: 10.1097/01.mlr.0000250483.85507.04 8.shumway-cook a, brauer s, woollacott m. predicting the probability for falls in community-dwelling older adults using the timed up & amp; go test. phys ther. 2000; 80: 896–903 9.gaunaurd i, kristal a, horn a, krueger c, muro o, rosenberg a, et al. the utility of the 2-minute walk test as a measure of mobility in people with lower limb amputation. arch phys med rehabil. 2020; 101: 1183–1189. doi: 10.1016/j.apmr.2020.03.007 10.dillon mp, major mj, kaluf b, balasanov y, fatone s. predict the medicare functional classification level (k-level) using the amputee mobility predictor in people with unilateral transfemoral and transtibial amputation. prosthetics orthot int. 2018; 42: 191– 197. doi: 10.1177/0309364617706748 11.balbi ll, secco mz, pinheiro bb, et al. validade de construto do teste de caminhada de 2 minutos para pacientes com amputação de membro inferior protetizados [construct validity of the 2-minute walk test for patients with lower limb amputation using prosthesis]. fisioter e pesqui 2021; 28: 393–399. doi: 10.1590/1809-2950/21009428042021 12.meanley s, reed nk. an “appropriate technology” trans-femoral prosthesis, using materials available in nepal. prosthetics orthot int. 1998; 22: 123–128. doi: 10.3109/03093649809164473 13.karatzios c, loiret i, luthi f, leger b, carre jl, saubade m, et al. transcultural adaptation and validation of a french version of the prosthetic limb users survey of mobility 12-item short-form (plus-m/fc-12) in active amputees. ann phys rehabil med. 2019; 62: 142–148. doi: 10.1016/j.rehab.2019.02.006 14.balkman g, samejima s, aoki d, hafner b. japanese translation of the prosthetic limb users survey of mobility. can prosthetics orthot j. 2018; doi: 10.33137/cpoj.v1i2.32017 15.brooks d, parsons j, hunter jp, devlin m, walkeret j. the 2minute walk test as a measure of functional improvement in persons with lower limb amputation. arch phys med rehabil. 2001; 82: 1478–1483. doi: 10.1053/apmr.2001.25153 16.iacobucci d, duhachek a. advancing alpha: measuring reliability with confidence. j consum psychol. 2003; 13: 478–487. doi:10.1207/s15327663jcp1304_14 https://doi.org/10.33137/cpoj.v6i1.41310 https://plus-m.org/translations.html https://apps.who.int/iris/handle/10665/354357 6 bajracharya ar, seng-iad s, sasaki k, guerra g. cross-cultural adaptation and validation of the nepali version of the prosthetic limb users survey of mobility short-form (plus-m™/nepali-12sf) in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.1. https://doi.org/10.33137/cpoj.v6i1.41310 canadian prosthetics & orthotics journal issn: 2561-987x plus-m™/nepali-12sf bajracharya et al., 2023 17.condie e, scott h, treweek s. lower limb prosthetic outcome measures: a review of the literature 1995 to 2005.j prosthet orthot. 2006; p13-p45. doi:10.1097/00008526-200601001-00004 18.postma m, goedhart j. plots of data—a web app for visualizing data together with their summaries. plos biol 2019; 17: e3000202 19.hafner bj, morgan sj, askew rl, salem r. psychometric evaluation of self-report outcome measures for prosthetic applications. j rehabil res dev. 2016; 53: 797–812. doi: 10.1682/jrrd.2015.12.0228 20.reid l, thomson p, besemann m, dudek n. going places: does the two-minute walk test predict the six-minute walk test in lower extremity amputees? j rehabil med. 2015; 47: 256–261. doi: 10.2340/16501977-1916 21.jarvis hl, bennett an, twiste m, phillip rd, etherington j, baker r. temporal spatial and metabolic measures of walking in highly functional individuals with lower limb amputations. arch phys med rehabil. 2017; 98: 1389–1399. doi: 10.1016/j.apmr. 2016.09.134 22.waters rl, perry j, antonelli d, hislopet h. energy cost of walking of amputees: the influence of level of amputation. j bone joint surg am. 1976; 58: 42–6 23.bohannon rw. normative reference values for the two-minute walk test derived by meta-analysis. j phys ther sci. 2017; 29: 2224–2227. doi: 10.1589/jpts.29.2224 24.smith jd, guerra g. quantifying step count and oxygen consumption with portable technology during the 2-min walk test in people with lower limb amputation. sensors. 2021; 21(6), 2080. doi:10.3390/s21062080 25.torburn l, powers c, guiterrez r, perry j. energy expenditure during ambulation in dysvascular and traumatic belowknee amputees: a comparison of five prosthetic feet. j rehabil res dev. 1995; 32: 111–119 26.hafner bj, spaulding se, salem r, morgan sj, gaunaurd i, gailey r. prosthetists’ perceptions and use of outcome measures in clinical practice: long-term effects of focused continuing education. prosthet orthot int. 2017; 41: 266–273. doi: 10.1177/0309364616664152 27.renzi r, unwin n, jubelirer r, haag l. an international comparison of lower extremity amputation rates. ann vasc surg. 2006; 20: 346–350. doi: 10.1007/s10016-006-9044-9 28.paudel b, shrestha bk, banskota ak. two faces of major lower limb amputations. kathmandu univ med j (kumj). 2005; 3: 212–6 29.wurdeman sr, stevens pm, campbell jh. mobility analysis of amputees (maat 6): mobility, satisfaction, and quality of life among long-term dysvascular/diabetic prosthesis users-results of a crosssectional analysis. j prosthet orthot. 2021; 33: 161–167. doi: 10.1097/jpo.0000000000000304 https://doi.org/10.33137/cpoj.v6i1.41310 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 letter to the editor laakso l. letter to the editor regarding: evolving business models in orthotics. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.3. https://doi.org/10.33137/cpoj.v5i1.37717 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.37717 1 laakso l. letter to the editor regarding: evolving business models in orthotics. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.3. https://doi.org/10.33137/cpoj.v5i1.37717 letter to the editor letter to the editor regarding: evolving business models in orthotics laakso l.1,2 * 1 orthotics prosthetics canada (opc), toronto, canada. 2 custom orthotic design group ltd., mississauga, canada. dear canadian prosthetics & orthotics journal editorial board, i am the president of orthotics prosthetics canada (opc), the credentialing body for orthotic and prosthetic professionals in canada. opc exists for the fundamental purpose of assisting patients in maintaining functional and productive lives by setting standards of education, credentialing and practice for the healthcare professionals who provide orthotic and prosthetic care. the goals of opc are like that of the canadian prosthetics and orthotics journal (cpoj): your, “passion for promoting and disseminating knowledge” is consistent with our role of, “advancing the profession of orthotics and prosthetics through quality standards of practice, professional credentialing, education and awareness”. the purpose of this letter is to initiate a constructive dialogue, clarify some of the information provided in the cpoj recent article,1 “evolving business models in orthotics” and to highlight our concerns with respect to important context about the orthotic and prosthetic profession in canada that we feel was missing from the publication. the article1 states, “certification is limited to public education”. i will note that the pathway to becoming credentialed in canada includes an undergraduate degree in engineering, kinesiology, or related program prior to a two-year certificate program at an opc accredited orthotic and prosthetic school. after completion of the formal education program, candidates (referred to as residents) must complete a 3,450-hour residency and successfully complete the opc certification examinations. the policies, procedures, school curricula, educational objectives, and the examination themselves are based on a validated practice analysis and evidence-based examination methodologies. based on these facts, we hope it is clear that the process to become certified in canada is much more comprehensive than “public education”. the pathway to becoming a certified orthotist or certified prosthetist in canada is accredited by the international society of prosthetics and orthotics (ispo) which is the standard of reference for the world health organization (who) for prosthetic orthotic occupations. although the profession is not licensed provincially, due to several factors that include but are not limited to cost, it is regulated by opc and therefore recognized by many of the provincial health ministries, including alberta, the province under scrutiny. regulation is identified as a core pillar within the scope of opc, whose mandate is, “to protect the public and advance the profession of orthotics and prosthetics through quality standards of practice, professional credentialing, education and awareness”. further, professional credentialing makes up another core pillar of opc, which is validated through the external parties of the ispo, the who, several provincial ministries of health and federal healthcare programs. certification of the profession in canada is recognized globally and is one of six entities that employ nine core practitioner standards including minimum education standards, entry level competency standards, scope of practice, code of ethics, course accreditation, continuing profession education, language standards, recency of practice and return to practice standards within the orthotics and prosthetics profession worldwide.2 the who has stated, in the document, prosthetics for orthotics standards & implementation guide,3 standard 25, “prosthetics and orthotics services should be provided by competent, adequately trained professionals.” opc certified members are recognized and credentialled by ispo and therefore recognized by the who as the trained orthotic and prosthetic professionals in canada. the standards within the guide are part of the requirements for canada to fulfill in order to meet our obligations under the convention on the rights of persons with disabilities (crpd). open access volume 5, issue 1, article no.3. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index * corresponding author linda laakso, msc co(c) fcbc, opc president orthotics prosthetics canada (opc), toronto, canada. custom orthotic design group ltd., mississauga, canada. email: lindalaakso@customorthotic.ca orcid id: https://orcid.org/0000-0002-1636-3717 opc website: https://opcanada.ca/ https://doi.org/10.33137/cpoj.v5i1.37717 https://opcanada.ca/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:lindalaakso@customorthotic.ca https://orcid.org/0000-0002-1636-3717 https://opcanada.ca/ 2 laakso l. letter to the editor regarding: evolving business models in orthotics. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.3. https://doi.org/10.33137/cpoj.v5i1.37717 issn: 2561-987x letter to the editor laakso l., 2022 cpoj to clarify the comments regarding number of practitioners we have in canada, i would like to share the following information: 1. opc has identified and acknowledged a potential shortage in the number of practitioners in the future and is addressing the issue through our national education standards project. we are working to establish more education opportunities based on demographic data. in fact, two additional students are enrolled within the current programs in the 2021-2022 school year cohort. if alberta, or any other jurisdiction has recognized a shortage of practitioners, opc would welcome the opportunity to assist in the creation and facilitate the development of an accredited orthotics and prosthetics program at one of the universities in alberta or local province. 2. since 2010, we have seen 18% growth in the number of practitioners in canada and we strive to continue to work towards the goal set by the who of 15-20 prosthetists/orthotists per million people.4 a final call to action from the article is to recognize people who are trained in orthotics and prosthetics from outside of canada. to be clear, the role of opc is to protect the public in canada and recognizes that the standards of practices from different countries are not the same as it is in canada. opc provides a pathway for foreign trained applicants, including those who have been recognized by ispo. it is important to note however, that ispo sets standards for education that are global and do not reflect the specific scope of practices of various countries or jurisdictions. ispo education standards are setting specific and are vetted by experts in each of those settings for schools to become accredited. in that respect, although ispo sets a minimum standard for education, it is not always equal to the minimum standard of practice in orthotics and prosthetics in canada. therefore, there may be variance in training pathways and competencies of graduates that require assessment specific to the context in canada. orthotics and prosthetics canada has in place an objective and transparent assessment for graduates from foreign trained pathways and programs. by having all practitioners achieve a minimum standard for entry to practice as developed based on a practice analysis within canada, we are creating a consistent standard that reflects the needs and expectations of patients and healthcare professionals within our country. many health care professions including the medical council of canada and the canadian physiotherapy association have similar practices with respect to people who are educated and/or trained outside of our borders. i hope that this has provided some clarity with respect to the stakeholder perspective article1 that you have published. if you, or any of your readers require more information or clarification, please do not hesitate to contact us. acknowledgements i would like to thank the following persons for helping with the preparation of this letter: helen cochrane, msc, cpo (c); seamus gearin, cae, opc executive director; scott hedlund, cp(c), opc president elect; and loren schubert, msc, cp(c), opc treasurer. declaration of conflicting interests i have the following conflicts of interest to declare: i am president, orthotics prosthetics canada (opc), the past president, international society of prosthetics and orthotics canada (ispo canada) and i am an owner, practitioner of the custom orthotic design group ltd. in mississauga, canada. references 1.schneider n. evolving business models in orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.3. https://doi.org/10.33137/cpoj.v4i2.35876 2. clarke l, puli l, ridgewell e, dillon mp, anderson s. regulation of the global orthotist/prosthetist workforce, and what we might learn from allied health professions with international-level regulatory support: a narrative review. hum. resour. health. 2021 dec;19(1):1-4. doi: 10.1186/s12960-021-00625-9 3.standards for prosthetics and orthotics, part 1: standards [internet]. world health organization. [cited 2021 october 22]. available from: https://apps.who.int/iris/bitstream/handle/10665/259209/97892415 12480-part1-eng.pdf?sequence=1&isallowed=y 4.standards for prosthetics and orthotics, part 2: implementation manual [internet]. world health organization. [cited 2021 october 22]. available from: https://apps.who.int/iris/bitstream/handle/10665/259209/97892415 12480-part2-eng.pdf?sequence=2&isallowed=y https://doi.org/10.33137/cpoj.v5i1.37717 https://opcanada.ca/ https://ispo372224799.wordpress.com/ https://www.customorthotic.ca/ https://www.customorthotic.ca/ https://doi.org/10.33137/cpoj.v4i2.35876 https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part1-eng.pdf?sequence=1&isallowed=y https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part1-eng.pdf?sequence=1&isallowed=y https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part2-eng.pdf?sequence=2&isallowed=y https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part2-eng.pdf?sequence=2&isallowed=y all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.36365 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 stakeholder perspectives a preliminary cost-utility analysis of the prosthetic care innovations: basic framework frossard l1-4* 1 yourresearchproject pty ltd, brisbane, australia. 2 griffith university, gold coast, australia. 3 university of the sunshine coast, maroochydore, australia. 4 queensland university of technology, brisbane, australia. introduction the revolutionary car maker and industrialist henry ford (1863-1947) said, “if you think of standardization as the best that you know today, but which is to be improved tomorrow; you get somewhere.” the automobile and healthcare industries might be two worlds apart. however, they both thrive on standardization because it is the key to efficiency and safety. hence, efforts are needed to develop a standard of care. standardization could also be applied to assess the socio-economic benefits of prosthetic care intervention. this article focuses on developing a basic framework of preliminary cost-utility analysis (cua) of innovations suitable to improve prosthetic fittings. economic evaluations of prosthetic care innovations promoters of prosthetic care interventions, including endusers, providers of prosthetic solutions, and administrators of healthcare organizations, are increasingly motivated to demonstrate the socio-economic benefits of their innovations.1-3 open access volume 4, issue 2, article no.10. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract a preliminary cost-utility analysis (cua) of prosthetic care innovations can provide timely information during the early stage of product development and clinical usage. concepts of preliminary cuas are emerging. however, several obstacles must be overcome before these analyses are performed routinely. disparities of methods and high uncertainty make the outcomes of usual preliminary cuas challenging to interpret, appraise and share. these shortcomings create opportunities for a basic framework of preliminary cuas. first, i introduced a basic framework of a preliminary cua built around a series of constructs and hands-on recommendations. then, i appraised this framework considering the strengths and weaknesses, barriers and facilitators, and return on investment. the design of the basic framework was determined through the review of health economic and prosthetic-specific literature. a preliminary cua comparing the costs and utilities between usual intervention and an innovation could be achieved through a 15-step iterative process focusing on feasibility, constructs, analysis, and interpretation of outcomes. this cua provides sufficient evidence to identify knowledge gaps and improvement areas, educate about the design of subsequent full cuas, and obtain fast-track approval from governing bodies. like previous cuas, the main limitations were inherent to the constructs (e.g., narrow perspective, plausible scenarios, mid-term time horizon, substantial assumptions, data mismatch, high uncertainty). key facilitators potentially transferable across preliminary cuas of prosthetic care innovations included choosing abided constructs, capitalizing on prior schedules of expenses, and benchmarking baseline or incremental utilities. this new approach with preliminary cua can simplify the selection of methods, standardize outcomes, ease comparisons between innovations, and streamline pathways for adoption. further collegial efforts toward validating standard preliminary cuas will facilitate access to economic prosthetic care innovations, improving the lives of individuals suffering from limb loss worldwide. citation frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 keywords artificial limbs, bionic limbs, boneanchored prosthesis, costeffectiveness, cost-utility, health economic evaluation, health technology assessment, prosthesis, socket-suspended prosthesis * corresponding author laurent frossard (phd), professor of bionics, yourresearchproject pty ltd, brisbane, australia. e-mail: laurentfrossard@outlook.com orcid number: https://orcid.org/0000-0002-0248-9589 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.36365 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.36365 mailto:laurentfrossard@outlook.com https://orcid.org/0000-0002-0248-9589 2 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e either health technology assessment (hta) or health economic evaluation (hee), or both of prosthetic care innovations are imperative to systematically assess the indirect and unintended clinical and economic consequences of an intervention.4-6 practically, there is an ever-increasing demand for cuas comparing the usual and new interventions using the incremental cost-utility ratio (icur). the icur is based on the incremental costs expressed in monetary units and utilities expressed in quality-adjusted life-year (qaly) over time compared to the willingness-to-pay threshold (wtp).4-9 as detailed in frossard (2021), early, preliminary, and full cuas can be conducted at the early, middle, and late phases of product development and clinical acceptance of innovations, respectively.3 full cuas, including primary and modeling analyses, can produce comprehensive outcomes, but they require substantial resources and lack timeliness. promoters could rely on strong recommendations that might be provided after a wide clinical adoption. full cuas have been used to demonstrate the health economic benefits of socket fitting interventions and fitting of advanced prosthetic components (microprocessor-controlled knees, energy-storing, and return feet) for socket-suspended and socket-free prostheses.7,8,10-19 earlier cuas could be conducted around the initial and middle stages of innovation development when clinical usage is still limited. these analyses could provide timely outcomes, but they presented high uncertainty. promoters might consider tentative recommendations of likely consequences that could be used to refine product development and clinical introduction. recent preliminary cuas considered the potential benefits of transfemoral and transtibial bone-anchored prostheses from the australian government’s prosthetic care perspective.7,8,14,20-22 emergence of preliminary cuas concepts of preliminary cuas are emerging.1 however, several obstacles must be overcome before preliminary cuas are routinely performed by promoters of prosthetic care innovations. for instance, multiple pathways and disparity constructs make the outcomes of these cuas (e.g., costs, utilities, icurs) challenging to interpret (e.g., comparison between innovations, generalization across healthcare), appraise (e.g., consolidated health economic evaluation reporting standards (cheers), consensus health economic criteria (chec) extended checklists) and share (e.g., publication).3,23-25 promoters rely on their abilities to make valid assumptions while opting for a specific cua pathway of innovations.1 however, this does not mean that preliminary cuas of a given innovation must be highly individualized. arguably, the organization of the delivery and assessment of prosthetic care might be sufficiently transferable across innovations to consider a uniform approach to preliminary cuas.7,8,14,20 need for a basic framework of a preliminary cua the shortcomings of preliminary cuas and the standardization of prosthetic care create opportunities for a basic framework of preliminary cuas. such a framework should be built based on fundamentals, applied principles of health economics, and recent preliminary cuas of socketfree attachment for transfemoral and transtibial prostheses.7,8,14 the primary purpose of this article was to introduce a basic framework including a 15-step iterative process focusing on feasibility, constructs, analysis, and interpretations of outcomes of a preliminary cua of prosthetic care innovations. practically, a series of constructs and handson ways to gather information was presented. furthermore, i recommended some facilitators transferable across preliminary cua of prosthetic care innovations. the secondary purpose was to appraise this basic framework considering potential strengths and weaknesses, barriers and facilitators, and returns on investment of the proposed preliminary cua. basic framework an overview of the iterative process of the basic framework of a preliminary cua of a prosthetic care innovation is presented in figure 1. this preliminary cua was designed to compare the costs and utilities before or without (usual intervention) and after or with an innovation suitable to improve prosthetic fittings (new intervention).4-6 next, all 15 steps of the process were individually presented, including a brief description of the concept, the specific aim, and some recommendations on ways to list of abbreviations chec: consensus health economic criteria extended checklist cheer: consolidated health economic evaluation reporting standards checklist cua: cost-utility analysis eq-5d: euroqol-5 dimension icer: incremental cost-effectiveness ratio icur: incremental cost-utility ratio k: medicare functional classification level qaly: quality-adjusted life-year sf36: 36-item short form survey wtp: willingness-to-pay threshold https://doi.org/10.33137/cpoj.v4i2.36365 3 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e proceed that could facilitate the process when needed. some barriers and facilitators were presented for the sake of completion, although they were basic and possibly evident for those astute in hees and cuas (e.g., review literature, consult clinicians).4-6 appraisal of the proposed preliminary cua using the cheers and chec-extended checklists is detailed in the supplementary material.23-25 determine feasibility this initial phase determines if the intended preliminary cua is achievable depending on the strength of information available (figure 1.1). this phase is organized around a three-step waterfall process with a decision point at every step to make sure resources are invested only if preliminary cua is feasible. the analysis can stop at any step if the preliminary information is deemed unsatisfactory and could be revisited later on. obtaining sufficient information leads to the next steps of the analysis. investigate product (step 1a) this step gathers information about the clinical pathways of the innovation, including the technical description of the device and the surgical, medical, rehabilitation, and prosthetic care procedures like patient screening (e.g., clinical indications and contraindications), among others. ultimately, this step reveals the unique value additions of the innovation compared to other interventions that could alleviate the current shortcomings of prosthetic fittings.3,26-31 some obvious facilitators include the literature review and engagements with suppliers and clinicians to access guidelines and expert opinions. search evidence of safety (step 1b) this step searches for what ijzerman and steuten (2011) called “likely safety” including some indications and preferably early evidence of the safety level of the 2a define perspective 2b define time horizon 2c identify scenarios 2d set discount 2e assess uncertainty 2. outline constructs 3a estimate costs 3b estimate utilities 3d compare with wtp 3. conduct analysis 4a consider limitations 4b interpret outcomes 4. interpret outcomes 1. determine feasibility 1a investigate product 1b search evidence of safety 1c search evidence of efficacy yes no no no abandon and revisit later yes yes favourable 4c outline implementation planning cua 3c calculate icurs no yes figure 1: overview of basic framework of preliminary cost-utility analysis (cua) of prosthetic care innovations including on a 15-step iterative process. icur: incremental cost-utility ratio, wtp: willingness-to-pay threshold. https://doi.org/10.33137/cpoj.v4i2.36365 4 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e innovation reported in terms of adverse events.1 socketbased solutions should report the incidence of pain, slippage, pistoning, skin damages (e.g., allergies), and falls, to name a few.29,32-36 socket-free innovations involving endo-skeletal osseointegrated implants with or without percutaneous parts should report pain, falls, stoma and soft tissue inflammation, loosening, periprosthetic fractures, breakage of implant parts, deep and superficial infections, intake of antibiotics, and removal of the implant.37-39 levels of evidence (i.e., level i-vii) and knowledge gaps should be considered when deciding the worthiness of the findings. preliminary cua should be typically conducted shortly after commercialization when clinical use remains limited to a small group of patients. therefore, evidence of safety for large cohorts (e.g., statistical power) over an extended observational study (e.g., several years follow-up) produced by independent parties might be desirable but unlikely. alternatively, early evidence provided by manufacturers outside or within a registered clinical trial is expected. level vi (e.g., single descriptive or qualitative study) or even level vii (e.g., opinion of authorities and/or reports of expert committees) of evidence could be found in this step. contemplating indications of the innovation’s safety with a benevolent outlook is acceptable considering that only the safety prospect should be deemed sufficient to lead to the next step. search evidence of efficacy (step 1c) this step searches for what ijzerman and steuten (2011) also called “likely efficacy,” including indications and, preferably, early evidence of the efficacy of the innovation.1 efficacy includes, amongst others, self-reported satisfaction (e.g., orthotics and prosthetics survey, quebec user evaluation of satisfaction with assistive technology, socket prosthetic comfort score), the performance of physical tasks (e.g., berg balance scale, timed get up and go, walking speed, twoor six-minute walk tests, functional ambulation profile, amputee mobility predictor with prosthesis), and specific (e.g., questionnaire for persons with a transfemoral amputation) and generic (e.g., 36-item short form survey (sf36), euroqol-5 dimension (eq-5d)) health-related quality of life indicators (e.g., quality-adjusted life year, disability-adjusted life year).33,34,36,40-42 evidence of efficacy might be easier to find because manufacturers tend to assess the benefits of innovations before the harms. nonetheless, finding strong evidence of efficacy might be challenging for the same reasons indicated in step 1b. levels of evidence (i.e., level i-vii) and knowledge gaps should be considered when deciding the value of the finding. a critical facilitator is the health-related quality of life data review that can be readily mapped into qaly (e.g., sf36, eq-5d).43 the absence of convertible health-related quality of life data is likely to stop the preliminary cua because completion of step 3b would be impractical. any datasets that can be used to create either a baseline or incremental utility or both utilities with the innovation should be considered (e.g., an estimate of gain post-intervention). outline constructs this five-step phase defines the list of typical parameters framing a preliminary cua (figure 1.2). define perspective (step 2a) preliminary cuas can be conducted from a broad taxpayer or healthcare perspective.6,15 however, surgical, medical, and prosthetic care costs are often undertaken in whole or in part by tertiary, primary, and secondary or allied health care services of government healthcare organizations or private companies operating together or separately.2,15,20,44-46 all costs are rarely collected in whole and reported to relevant services using a single integrated financial system. this step determines which perspective might be the most sensible, considering that preliminary cuas can focus on a reasonably narrow perspective. considering a government prosthetic care perspective to perform a preliminary cua of a prosthetic care innovation seems indicated.7,8,14,21 define time horizon (step 2b) the length of time over which the innovation outcomes can be evaluated is called the time horizon. choosing the appropriate time horizon can be problematic.47,48 this step aims at finding a compromise around a time horizon that is long enough to provide realistic and most probable intended benefit with the least approximation errors.15,16,47-53 funding cycles of a preliminary cua of an innovation advancing prosthetic fittings should consider the lifetime of the prosthetic components (e.g., socket, artificial joints).7,8,14 i suggest that a suitable compromise might be, at least, six years, because of the predictability of costs and the lifetime of components (e.g., two cycles of three years for a foot, three cycles of two years for a knee).7,8 identify scenarios (step 2c) scenarios are commonly used to characterize the consequences of interventions for various health states and specific cases. improvement in functional outcomes is often a consequence of choice. level of function can be assess using medicare functional classification level (k-level). in principle, up to 15 scenarios can be considered when comparing possible progressions across the five k-levels ranging from k0 to k4 with and without the innovation (table 1). this step identifies a limited series of scenarios that are the most plausible. https://doi.org/10.33137/cpoj.v4i2.36365 5 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e i recommend exploring between three and five realistic scenarios including, the best, base, and worse cases depending on foreseeable costs and utility consequences of the innovation.7,8 table 1: matrix of 15 possible scenarios comparing progressions of functional outcomes across the five medicare functional classification level (k-level) ranging from k0 to k4 without (usual) and with (new) intervention that could be considered in step 2c. set discount (step 2d) discounting is the process of reducing future values of costs and utilities to their present values.48 the standard practice for full cua is to discount values at 3% over the time horizon.48 this step ascertains the extent to which this rate should apply to the intended preliminary cua. i consider that no discount might be applied when the time horizon is reasonably short (e.g., up to six years) and the highest costs of the intervention are spent in the first few years of the funding cycle.7,8 assess uncertainty (step 2e) estimates of costs and utilities are subjected to uncertainty depending on the sources of the data. comprehensive cua involves complex markov-state transition models designed to investigate the impact of cost and utility estimates and provide parameters, models, and generalizable uncertainties.15,16,50,51,53 the sensibility of the outcomes of these models is also considered based on the probability of occurrence of events that might affect the analysis.15 this step aims to limit uncertainty by considering a limited number of practical events or health states. i recommend making conservative assumptions that the innovation marginally improves the prosthetic fittings (e.g., reduce socket fittings by only one per annum). considering multiple events or health states is beyond the scope of this analysis (e.g., reduce socket fittings by two, three, or more per annum). uncertainty of cost information of real and estimated costs, extracted from the schedule and financial records, can be reported using a variable called “prediction” presented in frossard et al. (2018, 2020).7,8 this variable corresponds to the relative real over the total costs. a prediction of 0% and 100% indicated that the total cost is fully extracted from schedules and financial records, respectively. sensibility of datasets and the outcomes can be reported using basic descriptive statistics (e.g., mean, standard deviation, coefficient of variation, median, interquartile range, 95% confidence intervals, minimum, maximum, range).7,8,14 in some cases, inter-participant variability of costs might be reported using the coefficient of variation, where coefficients inferior to 33%, between 34% and 66%, and superior to 66% indicate low, moderate, and high intervariability, respectively.8 conduct analysis this four-step phase estimates costs, utilities, and icurs based on the constructs determined in the previous phase (figure 1.3). estimate costs (step 3a) ideally, actual labor and parts costs of prosthetic care with usual intervention and the innovation, can be extracted from financial systems for the largest possible cohort of participants. however, only partial information on the primary post-treatment costs over the time horizon might be available (steps 1c, b). i advise considering generic costs organized in schedules of allowable expenses.14,20 these schedules can be used, in part or whole, to estimate the most probable costs for prosthetic care without or with the innovation.7,8,14 a schedule is a matrix that presents costs at the intersection list of tasks in rows and the timeline of interventions between the columns.3 the type of tasks and frequency of interventions should be based on the standard of care recommended by clinicians and government agencies.20,54,55 the actual costs of labor and parts should be consistent with allowable expenses supported by reimbursement schemes (e.g., l-codes), particularly when analyzing from the healthcare perspective. examples of schedules of allowable expenses used for preliminary cuas of lower limb bone-anchored prostheses can be used as a template.7,8,14 healthcare organizations tend to provide support for categories of components depending on functional levels (e.g., k-levels).56 here, prosthetists are free to prescribe a model and brand according to the patients’ specific needs. thus, allocating lump sums rather than price tags for specific prosthetic components may be more acceptable. in all cases, i recommend presenting the source and analysis of datasets (e.g., actual vs. estimated). the series of assumptions made to estimate costs must be justified (e.g., hours of labor for socket fittings, frequency of replacement of prosthetic components).14,20 new k0 k1 k2 k3 k4 u s u a l k0 scenario 1 scenario 2 scenario 3 scenario 4 scenario 5 k1 scenario 6 scenario 7 scenario 8 scenario 9 k2 scenario 10 scenario 11 scenario 12 k3 scenario 13 scenario 14 k4 scenario 15 https://doi.org/10.33137/cpoj.v4i2.36365 6 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e table 2: overview of manageable barriers and transferrable facilitators of basic framework of preliminary cost-utility analysis (cua) comparing usual intervention (e.g., socket-based, socket-free using osseointegration) and a prosthetic care innovation susceptible to improve prosthetic fittings. icur: incremental cost-utility ratio, k-level: medicare functional classification level, qaly: quality-adjusted life-year, $: australian dollar. barriers facilitators 1. determine feasibility investigate product (step 1a) 1. understand the technical description of the ..treatment (e.g., identify parts) 1. find technical information provided by the supplier of the innovation (e.g., website, flyer) 2. understand the surgical, medical, rehabilitation .and prosthetic care procedures (e.g., understand .clinical indications and contraindications) 2. find clinical guidelines for the prescription of the innovation provided by the supplier 3. seek opinion of expert clinicians about indications and contraindications 3. understand unique added value of the innovation .compared to other interventions 4. extract information provided in publications about innovation 5. identify uniqueness of the treatment after cross-comparison with other interventions 6. establish if the potential benefits of the innovation justified investigating safety search evidence of safety (step 1b) 4. foresee indications of safety of the innovation 7. sass out potential harms of innovation 8. compare potential risks with other interventions 5. find early evidence of safety of the innovation 9. search literature focusing on safety of the innovation 10. review level of evidence of adverse events (i.e., level i-vii, registered clinical trial) 6. identify evidence gaps about safety of the .innovation 11. acknowledge evidence gaps about safety of the innovation 12. establish if evidence of safety of the innovation justified investigating efficacy search evidence of efficacy (step 1c) 7. foresee indications of efficacy of the innovation 13. sass out potential benefits of innovation 14. compare potential benefits with other interventions 8. find evidence of the efficacy of the innovation 15. search literature focusing on efficacy of the innovation 16. review level of evidence of satisfaction, function (e.g., performance of physical tasks) and .health-related quality of life (i.e., level i-vii, registered clinical trial) 9. identify evidence gaps about efficacy of the .innovation 17. acknowledge evidence gaps about efficacy of the innovation 18. establish if health-related quality of life data of the innovation is sufficient to justified continuing .cua 2. outline constructs define perspective (step 2a) 10. choose healthcare perspective considering surgical, medical and prosthetic care expenses 19. accept that considering whole care expenses together might have little relevance, in fine, because of the separation between primary, secondary, and tertiary services in typical healthcare systems 20. simplify analysis be considering only a prosthetic care perspective define time horizon (step 2b) 11. find the time horizon that is long enough to provide realistic outcomes but the least subjected to large approximation errors 21. understand that prediction of costs of prosthetic components over the long period of time is .more likely to be grossly inaccurate 22. acknowledge studies suggesting that a rather short time horizon would be indicated for the .preliminary analysis 23. consider that six-year time horizon might be a suitable compromise because of the predictability .of costs and lifetime of components identify scenarios (step 2c) 12. identify a small series of plausible scenarios 24. consider 15 scenarios for all possible progressions across k-levels 25. select up to five realistic scenarios most likely to represent expected clinical outcomes with the innovation including worse, best and base cases set discount (step 2d) 13. ascertain to which extent typical discounting rate should apply 26. consider applying no discount when time horizon is short enough to predict costs 27. consider applying no discount when most important costs might occur at the beginning of the .cycle assess uncertainty (step 2e) 14. find ways to determine the uncertainty 28. make the conservative assumption that the innovation would minimally improve prosthetic .fittings 29. consider that looking at multiple events or health states is beyond the scope of this analysis 15. find ways to present the sensibility 30. choose to report sensibility analysis using only basic descriptive statistics including coefficient of .variation https://doi.org/10.33137/cpoj.v4i2.36365 7 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e a conservative method to estimate costs is to assume that full allowable expenses are claimed, although some users might choose to keep components even after the warranty period or discard cosmetic covers. alternatively, i consider that all prosthetic tasks are performed by qualified prosthetists even if some tasks might be undertaken by a technician working at a lower hourly rate. however, these suggestions could be discarded, particularly when the analyses focus on innovations improving service delivery.57 estimate utilities (step 3b) primary utilities measured for groups of participants without and with the innovation are preferable, depending on the relevant healthcare organization. however, like costs, table 2: continued. barriers facilitators 3. conduct analysis estimate costs (step 3a) 16. estimate costs for the provision of prosthetic .care without and with the innovation 31. acknowledge that primary costs with the innovation might not be available in relevant healthcare system 32. create schedules of allowable expenses for labour and parts for the provision of prosthetic care .without and with innovation 33. apply costings recommended by the healthcare system estimate utilities (step 3b) 17. estimates utilities experienced by users without .and with the innovation 34. acknowledge that primary utility data with the innovation might not be available for groups of users involved in relevant healthcare system 35. search utility information with the innovation in the literature 36. consider utility information published and convert data to create baseline utility reported in qaly 37. assume that users experience a small increase of utilities with the innovation compare to .baseline 38. assume that utilities experienced without and with the innovation remain steady during the time horizon calculate icurs (step 3c) 18.determine which scenario could provide a tentative icur 39. assume that the base-case scenario should be correspond to the indicative icur compare with wtp (step 3d) 19.identify the sensible wtp commonly accepted in the relevant health care 40. consider that a conservative wtp is $40,000 per qaly that is significantly lower that oft-cited wtp 20.identify thresholds most likely to motivate promoters to continue the developments of the innovation 41. consider that an indicative icur costing less than $20,000 per qaly is most likely to motivate .promoters to continue the developments of the innovation 4. interpret outcomes consider limitations (step 4a) 21. understand the effects of the series of .assumptions 42. concede that analysis is noticeably limited by a series of assumptions 43. look at how costs might have been over-estimated 44. look at how utilities might have been under-estimated 45. acknowledge when icurs aggregates mismatched data interpret outcomes (step 4b) 22. assess how the treatment compared to other .interventions 46. estimate the range of costs and utilities that might be required to make the innovation cost.effective and below wtp 47. determine if the innovation has the potential to be more cost-effectiveness than competing .interventions 23. assess limitations to generalization of the .outcomes 48. concede that generalization of outcomes might be limited outline implementation strategy (step 4c) 24. gauge the worthiness of data to justify .introducing of the innovation in healthcare 49. establish how the indicative icur with the innovation stacks up against other interventions 50. decide if the analysis provided sufficient evidence to motivate promoters to encourage clinical .adoption in relevant healthcare 25. identify how information gathered during this .analysis could inform the design subsequent .full cua of the innovation 51. acknowledge that outline pathways for the clinical introduction of the innovation is beyond the ;scope of this analysis 52. detail how this information provided can inform subsequent primary and modelling cuas of the .innovation https://doi.org/10.33137/cpoj.v4i2.36365 8 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e primary utilities collected at the outset of the preliminary cua are likely to be unattainable. alternatively, i suggest using health-related quality of life data identified in step 1c to estimate baseline and incremental utilities published together or separately. for instance, the dataset from sf36 can be converted into qaly applying the ara and brazier regression model used by frossard et al. (2018).7,8,43 plausible estimates of incremental utilities could be based on the assumption that users of the innovation are likely to experience a gradual gain of qaly between the worse, base, and best cases scenarios.7,8 i recommend describing the sources and processing of datasets, including the criteria to select publications and summarize the study designs used to measure original primary utilities. gain of utilities should also be justified. calculate incremental cost-utility ratios (step 3c) this preliminary cua comes together when icurs are calculated using the formula icur = (costs with innovation – costs with usual intervention) / (utility with innovation – utility with usual intervention).4-6 icur should be calculated for each scenario and plotted on a conventional fourquadrant cost-utility plane diagram indicating if the provision of the prosthetic care with innovation is more costly and more effective (quadrant a: consider icur), more costly and less effective (quadrant b: dominated), less costly and less effective (quadrant c: consider icur), and less costly and more effective (quadrant d: dominant) than usual intervention.4-6 i advise considering an indicative icur corresponding to the base-case scenario.7,8 compare with the willingness-to-pay threshold (step 3d) typically, understanding outcomes of a cua involved comparing icur and wtp. the oft-cited wtp is approximately $50,000 per qaly, depending on healthcare organizations.6 based on figures frequently considered to determine the likelihood of adoption of an intervention, an indicative icur costing less than $20,000, between $20,000 and $100,000, and more than $100,000 per qaly could make the innovation most likely, likely, and unlikely, respectively, to motivate promoters to continue further product development and clinical introduction of the innovation.6 i advise a conservative wtp threshold of up to 20% lower than the recommended wtp (e.g., $40,000 per qaly).7,8 interpret outcomes this four-step phase ascertains the extent to which the understanding of the outcomes of this preliminary cua is sufficient to facilitate or curtail further product development and clinical introduction of the innovation (figure 1.4). consider limitations (step 4a) this step recognizes the impacts of assumptions on the overall outcomes of the analysis. the typical and specific limitations of calculations of icurs are discussed (e.g., mismatching datasets). i suggest exploring possible causes of cost overestimation (e.g., claiming full allowable expenses, tasks only performed by qualified prosthetist) and utilities underestimations (e.g., low incremental gains, consider utilities gained post-treatment consistent over time). i recommend acknowledging the extent to which the aggregate icurs mismatched data (e.g., sources, jurisdictions, onset, post-operative timeline).7,8 interpret outcomes (step 4b) this step considers the cost-effective conditions for the innovation. it ascertains by how much the qaly must be increased to offset its costs, and the requirements to make the indicative icur below wtp. i advise interpreting the analysis outcomes after comparing the costs, utilities, and icurs with other competing interventions that could improve prosthetic fittings. potential generalization of the outcomes should be investigated, considering the limitations. finally, i advise basing the recommendations for wider clinical usage and likelihood of adoption of the innovation on the figures presented in step 3d. outline implementation strategy (step 4c) this last step examines the innovation against other interventions and relevant healthcare cost-utility standards. decision-makers should comprehensively gauge whether the outcomes produced were robust enough to justify pursuing subsequent implementation strategy. weak or unfavorable outcomes might encourage innovators to rethink product development and revisit opportunities for preliminary cuas at a later stage. strong and favorable outcomes might warrant continuing further product development and clinical promotion of the innovation. i suggest highlighting the elements of the preliminary cua that could facilitate the design of the potential primary or modelling cuas of the innovation (e.g., within-trial and beyond-trial horizon studies).47 regardless of the recommendations, i advise outlining subsequent implementation strategies that could be deemed outside the scope of the analysis and the purpose of another process. appraisal of basic framework strengths and weaknesses the proposed basic framework will provide timely information. this preliminary cua will generate sufficient https://doi.org/10.33137/cpoj.v4i2.36365 9 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e evidence to identify gaps in evidence and improvement, educate about the design of primary or modeling studies, and fast-track approval of innovation from governing bodies. this framework carries the intrinsic limitations of the usual preliminary cuas mentioned in frossard (2021).3 the inherent limitations to the analysis include narrow perspective, plausible scenarios, and mid-term time horizon. the cost and utility estimates are built around bestknown evidence and substantial assumptions. icurs would be based on mismatched costs and utilities. reporting of the uncertainty and sensibility data will likely lack definition. altogether, i predicted that the analysis might have a weak, moderate, and strong capacity to address 9 (33%), 8 (30%), and 10 (37%) of the items in the cheers checklist, including 7 (44%), 6 (38%) and 3 (19%) of the items in the methods, and 2 (40%), 2 (40%), and 1 (20%) of the items in the results sections, respectively.23,24 the proposed preliminary cua might be capable and incapable of addressing items 11 (58%) and 8 (42%) in the checextended checklists, respectively.24,25 barriers and facilitators as outlined in table 2, i identified a total of 25 barriers that could be overcome by 52 facilitators likely to be transferable across preliminary cuas of prosthetic care innovations. i believe these key but not comprehensive recommendations can be included: • choosing abided constructs. the preliminary cua design (step 2), particularly the time horizon, emanated from educated choices integrating various basic and applied cua methodological approaches presented in guidelines and recent publications.48 i recommended considering constructs that are consistent with recent preliminary cua socket-free solutions.7,8,14 choosing similar constructs would significantly streamline decision-making in all steps 2a, b, c, and d. this should greatly facilitate the interpretation of the outcomes (step 4b) and the gauging of the value proposition of the innovation compared to other interventions (step 4c). this difference in outcomes between analyses could be minimally attributed to confounding constructs. • building on prior schedules of expenses. the cost estimates (step 3a) could be largely guided by an initial template of schedules considering the prosthetic care provision costs for lower limb socket-suspended and bone-anchored prostheses.7,8,14 some generic tasks and timeline of interventions could be transferable. other costs specific to each innovation must be tabulated into the new schedules recommended by clinicians and government agencies. • capitalizing on benchmark baseline and incremental utilities. the utility estimates (step 3b) could be educated by benchmark baseline and incremental utilities provided in the health economic literature focusing on socket-based or socket-fee prostheses.1013,15-19,57 returns on investment questions might be raised about the returns on investment of the proposed preliminary cua. although some safeguards were embedded into the initial feasibility phase to curtail unnecessary work, the entire preliminary cua requires noticeable efforts depending on the source of data (e.g., design schedules, extract costs, map utility). the returns might be unclear because of the important structural uncertainty, medium grade of evidence, and tentative recommendations.1 however, policymakers in the healthcare sector might see some benefits of systematically embedding such preliminary cua into their horizon scanning process.1 it can contribute to deciding whether a new prosthetic care intervention shows early signs of cost-utility. promoters of new interventions might deem this preliminary cua a worthwhile investment to support applications for healthcare approval.2 conclusions this study was an initial effort to standardize a basic framework of preliminary cua comparing the prosthetic care provisions with and without innovation suitable to improve prosthetic fittings. this new approach to preliminary cua has the potential to simplify the selection of methods, standardize outcomes, ease comparisons between innovations and streamline pathways for adoption while facilitating the production of a body of literature on prosthetic health economics. insights into the next phase of development of this method might come from masaaki imai, a japanese organizational theorist, and management consultant. he stated that it is impossible to improve any process until it is standardized. he added that if the process is shifting from here to there, then any improvement will just be one more variation that is occasionally used and mostly ignored. one must standardize, and thus stabilize the process, before continuous improvement can be made. therefore, i welcome further experiments of this proposed analysis with emerging prosthetic care innovations. this will refine and validate the standard basic framework of preliminary cua. hopefully, this collegial effort will facilitate the adoption of economic prosthetic care innovations that could improve the lives of individuals suffering from limb loss worldwide. https://doi.org/10.33137/cpoj.v4i2.36365 10 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e call to action • continue the discussion between promoters of prosthetic care innovations around the use and validation of preliminary cuas framework. • inspire authors of health economic evaluations to roadtest the proposed framework with a series of emerging prosthetic care innovations susceptible to improve prosthetic fittings. • encourage authors of health economic evaluations of prosthetic care innovations to capitalize on the benefits of early and preliminary cuas during development of the innovations. acknowledgements the author wishes to express his gratitude to debra berg and gregory merlo for their support. declaration of conflicting interests the author is in the view that these competing interests do not conflict with the content of this manuscript. laurent frossard, director and chief scientist officer of yourresearchproject pty ltd, has worked as consultant for several organisations on non-related educational programs and projects of research focusing on recording loading data, developing of database to record clinical outcomes as well as drafting grants and manuscripts for cognitive institute, exercise & sports science australia, griffith university, ipug pty ltd, middlesex university, new zealand artificial limb service, osseointegration group of australia pty ltd, ossur, poly-orthodox international, queensland artificial limb service, queensland university of technology, return to work-south australia, south australia health, tequir s.l, university of the new south whales, university of the sunshine coast. sources of support this study was funded by yourresearchproject pty ltd. references 1.ijzerman mj, steuten lm. early assessment of medical technologies to inform product development and market access: a review of methods and applications. appl health econ health policy. 2011; 9(5): 331-47. doi: 10.2165/11593380-00000000000000 2.kannenberg a, seidinger s. health economics: the perspective of a prosthetic manufacturer. j prosthet orthot. 2019; 31(1s). doi:10.1097/jpo.0000000000000234 3.frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. can prosthet orthot j. 2021; v4,i2. doi:10.33137/cpoj.v4i2.36364. 4.cohen dj, reynolds mr. interpreting the results of costeffectiveness studies. j am coll cardiol. 2008; 52(25): 2119-26. doi: 10.1016/j.jacc.2008.09.018 5.cape j, beca j, hoch j. introduction to cost-effectiveness analysis for 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10.1177/0309364610392812 11.boone da. the economic value of mobility with a prosthesis. j prosthet orthot. 2019; 31(1s). doi: 10.1097/jpo. 0000000000000231 12.cutti ag, lettieri e, verni g. health technology assessment as theoretical framework to assess lower-limb prosthetics—issues and opportunities from an international perspective. j prosthet orthot. 2019; 31(1s):55-73. doi: 10.1097/jpo.0000000000000235 13.haggstrom ee, hansson e, hagberg k. comparison of prosthetic costs and service between osseointegrated and conventional suspended transfemoral prostheses. prosthet orthot int. 2013; 37(2):152-60. doi: 10.1177/0309364612454160 14.frossard l, berg d, merlo g, quincey t, burkett b. cost comparison of socket-suspended and bone-anchored transfemoral prostheses. j prosthet orthot. 2017; 29(4):150-160. doi: 10.1097/jpo.0000000000000142 15.hansson e, hagberg k, cawson m, brodtkorb th. patients with unilateral transfemoral amputation treated with a percutaneous osseointegrated prosthesis: a cost-effectiveness analysis. bone joint j. 2018; 100-b(4):527-534. doi: 10.1302/0301620x.100b4.bjj-2017-0968.r1 16.brodtkorb th, henriksson m, johannesen-munk k, thidell f. cost-effectiveness of c-leg compared with non-microprocessorcontrolled knees: a modeling approach. arch phys med rehabil. 2008; 89(1): 24-30. doi: 10.1016/j.apmr.2007.07.049 17.gerzeli s, torbica a, fattore g. cost utility analysis of knee prosthesis with complete microprocessor control (c-leg) compared with mechanical technology in trans-femoral amputees. eur j health econ. 2009; 10(1): 47-55. doi: 10.1007/s10198-008-01029 18.cutti ag, lettieri e, del maestro m, radaelli g, luchetti m, verni g, et al., stratified cost-utility analysis of c-leg versus mechanical knees: findings from an italian sample of transfemoral amputees. prosthet orthot int. 2017; 41(3): 227-236. doi: 10.1177/ 0309364616637955 19.chen c, hanson m, chaturvedi r, mattke s, hillestad r, liu hh. economic benefits of microprocessor controlled prosthetic knees: a modeling study. j prosthet orthot. 2019; 31(1s) https://doi.org/10.33137/cpoj.v4i2.36365 11 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e 20.frossard l, merlo g, quincey t, burkett b, berg d. development of a procedure for the government provision of boneanchored prosthesis using osseointegration in australia. pharmacoeconomics. 2017; 1(4): 301-314. doi: 10.1007/s41669017-0032-5 21.frossard l. innovations of health services and economic evaluation of bone-anchored prosthesis using osseointegration: the queensland artificial limb service’s experience 2017 scientific report, ed. l. frossard. 2018, brisbane, australia: yourresearchproject. 19. 22.frossard l. data supporting the 2019 queensland artificial limb service’s science report about innovations of health services and economic evaluation of limb lower bone-anchored prostheses. 2020; mendeley data. doi:10.17632/r3b6wdtd8x.1 23.husereau d, drummond m, petrou s, carswell c, moher d, greenberg d, et al. consolidated health economic evaluation reporting standards (cheers)--explanation and elaboration: a report of the ispor health economic evaluation publication guidelines good reporting practices task force. value health. 2013; 16(2): 231-50. doi: 10.1016/j.jval.2013.02.002 24.van mastrigt ga, hiligsmann m, arts jj, broos ph, kleijnen j, evers sm, et al. how to prepare a systematic review of economic evaluations for informing evidence-based healthcare decisions: a five-step approach (part 1/3). expert rev pharmacoecon outcomes res. 2016; 16(6): 689-704. doi: 10.1080/14737167.2016.1246960 25.gerkens s, crott r, cleemput i, thissen jp, closon mc, horsmans y, et al. comparison of three instruments assessing the quality of economic evaluations: a practical exercise on economic evaluations of the surgical treatment of obesity. int j technol assess health care. 2008; 24(3): 318-25. doi: 10.1017/s0266462308080422 26.bui km, raugi gj, nguyen vq, reiber ge. skin problems in individuals with lower-limb loss: literature review and proposed classification system. j rehabil res dev. 2009; 46(9): 1085-90. doi: 10.1682/jrrd.2009.04.0052 27.kahle jt, klenow td, highsmith mj. comparative effectiveness of an adjustable transfemoral prosthetic interface accommodating volume fluctuation: case study. technology and innovation. 2016; 18(2-3):175-183. doi: 10.21300/18.2-3.2016.175 28.gholizadeh h, abu osman na, eshraghi a, arifin n, chung ty. a comparison of pressure distributions between two types of sockets in a bulbous stump. prosthet orthot int. 2016; 40(4):50916. doi: 10.1177/0309364614564022 29.paternò l, ibrahimi m, gruppioni e, menciassi a, ricotti l. sockets for limb prostheses: a review of existing technologies and open challenges. ieee trans biomed eng. 2018; 65(9): 19962010. doi: 10.1109/tbme.2017.2775100 30.meulenbelt he, geertzen jh, jonkman mf, dijkstra pu. determinants of skin problems of the stump in lower-limb amputees. arch phys med rehabil. 2009; 90(1): 74-81. doi: 10.1016/j.apmr.2008.07.015 31.turner s, mcgregor ah. perceived effect of socket fit on major lower limb prosthetic rehabilitation: a clinician and amputee perspective. archives of rehabilitation research and clinical translation. 2020; 2(3): 100059. doi: 10.1016/j.arrct.2020.100059 32.gholizadeh h, osman na, eshraghi a, ali s. transfemoral prosthesis suspension systems: a systematic review of the literature. am j phys med rehabil. 2014; 93(9): 809-23. doi: 10.1097/phm.0000000000000094 33.klenow td, kahle jt, fedel fj, ropp j, highsmith mj. comparative efficacy of transfemoral prosthetic interfaces. j prosthet orthot. 2017; 29(3): 130-136. doi: 10.1097/jpo.0000000000000135 34.eshraghi a, osman na, gholizadeh h, karimi m, ali s. pistoning assessment in lower limb prosthetic sockets. prosthet orthot int. 2012; 36(1):15-24. doi: 10.1177/0309364611431625 35.frossard la, tranberg r, haggstrom e, pearcy m, brånemark r. load on osseointegrated fixation of a transfemoral amputee during a fall: loading, descent, impact and recovery analysis. prosthet orthot int. 2010; 34(1): 85-97. doi: 10.3109/ 03093640903585024 36.frossard l, hagberg k, häggström e, gow dl, brånemark r, pearcy m. functional outcome of transfemoral amputees fitted with an osseointegrated fixation: temporal gait characteristics. j prosthet orthot. 2010; 22(1): 11-20. doi: 10.1097/jpo.0b013e3181ccc53d 37.osseointegrated prosthetic implants for people with lower-limb amputation: a health technology assessment [internet]. ont health technol assess ser. 2019;[cited 2021, june 9]. available from: http://www.hqontario.ca/evidence-to-improve-care/journalontariohealth-technology-assessment-series 38.kaulback k, jones a. osseointegrated prosthetic implants for lower limb amputation: a review of clinical effectiveness, costeffectiveness and guidelines [internet]. ottawa (on): canadian agency for drugs and technologies in health, 2017; [cited 2021, june 9]. available from: https://pubmed.ncbi.nlm.nih.gov/28825780/ 39.martin r. rapid review of osseointegration/ direct skeletal fixation-a report for nhs england [internet]. bazian ltd: uk, 2016; [cited 2021, june 9]. available from: https://www.ispo.org.uk/resources/bazian-report.pdf 40.frossard l, stevenson n, sullivan j, uden m, pearcy m. categorization of activities of daily living of lower limb amputees during short-term use of a portable kinetic recording system: a preliminary study. j prosthet orthot. 2011; 23(1): 2-11. doi: 10.1097/jpo.0b013e318207914c 41.dillingham tr, pezzin le, mackenzie ej, burgess ar. use and satisfaction with prosthetic devices among persons with traumarelated amputations: a long-term outcome study. am j phys med rehabil. 2001; 80(8): 563-71. doi: 10.1097/00002060-20010800000003 42.pezzin le, dillingham tr, mackenzie ej, ephraim p, rossbach p. use and satisfaction with prosthetic limb devices and related services. arch phys med rehabil. 2004; 85(5): 723-9. doi: 10.1016/j.apmr.2003.06.002 43.ara r, brazier j, deriving an algorithm to convert the eight mean sf-36 dimension scores into a mean eq-5d preference-based score from published studies (where patient level data are not available). value health, 2008. 11(7):1131-43. doi: 10.1111/j.1524-4733.2008.00352.x 44.tai bb, bae yh,le qa. a systematic review of health economic evaluation studies using the patient's perspective. value health. 2016; 19(6): 903-908. doi: 10.1016/j.jval.2016.05.010 https://doi.org/10.33137/cpoj.v4i2.36365 http://www.hqontario.ca/evidence-to-improve-care/journalontario-health-technology-assessment-series http://www.hqontario.ca/evidence-to-improve-care/journalontario-health-technology-assessment-series https://pubmed.ncbi.nlm.nih.gov/28825780/ https://www.ispo.org.uk/resources/bazian-report.pdf 12 frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.10. https://doi.org/10.33137/cpoj.v4i2.36365 issn: 2561-987x cost-utility analysis of the prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e 45.kaluf, b. provider perspective in the health care economics of lower-limb prosthetic rehabilitation. j prosthet orthot. 2019; 31(1s). doi:10.1097/jpo.0000000000000230 46.fish d. the development of coverage policy for lower extremity prosthetics: the influence of the payer on prosthetic prescription. j prosthet orthot. 2006; 18(6):125-129. doi:10.1097/00008526-200601001-00017 47.basu, a. and m.l. maciejewski, choosing a time horizon in cost and cost-effectiveness analyses. jama, 2019. 321(11): 1096. doi: 10.1001/jama.2019.1153. 48.tan-torres edejer t, baltussen r, adam t, hutubessy r, acharya a, evans db, et al. who guide to cost-effectiveness analysis [internet].world health organisation. 2003; [cited 2021, june 9]. available from: https://www.who.int/choice/publications/p_2003_generalised_cea. pdf?ua=1dfid 49.o'mahony jf, newall at, rosmalen jv. dealing with time in health economic evaluation: methodological issues and recommendations for practice. pharmacoeconomics. 2015; 33(12): 1255-68. doi: 10.1007/s40273-015-0309-4 50.sonnenberg fa, beck jr. markov models in medical decision making: a practical guide. med decis making. 1993; 13(4): 322-38. doi: 10.1177/0272989x9301300409 51.edwards ds, phillip rd, bosanquet n, bull am, clasper jc. what is the magnitude and long-term economic cost of care of the british military afghanistan amputee cohort? clin orthop relat res. 2015; 473(9):2848-55. doi: 10.1007/s11999-015-4250-9 52.gordon r, magee c, frazer a, evans c, mccosker k. an interim prosthesis program for lower limb amputees: comparison of public and private models of service. prosthet orthot int. 2010; 34(2): 17583. doi: 10.3109/03093640903510980 53.blough dk, hubbard s, mcfarland lv, smith dg, gambel jm, reiber ge. prosthetic cost projections for servicemembers with major limb loss from vietnam and oif/oef. j rehabil res dev. 2010; 47(4): 387-402. doi: 10.1682/jrrd.2009.04.0037 54.frossard l, ferrada l, berg d. survey on the quality of life of consumers fitted with osseointegrated fixation and bone-anchored limb prostheses provided by government organization. 2019; mendeley data. doi: 10.17632/bkbxxmrhfh.1 55.frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. can prosthet orthot j. 2018; 1(2). doi: 10.33137/cpoj.v1i2.31326 56.campbell jh, stevens pm, wurdeman sr. oasis 1: retrospective analysis of four different microprocessor knee types. rate. 2020;1-10. doi: 10.1177/2055668320968476 57.highsmith mj, kahle jt, lewandowski a, klenow td, orriola jj, miro rm, et al. economic evaluations of interventions for transtibial amputees: a scoping review of comparative studies. technol innov. 2016;18(2-3):85-98. doi:10.21300/18.2-3.2016.85. author scientific biography dr laurent frossard is a bionic limbs scientist who is passionate about developing ground-breaking prosthetic solutions to improve the lives of individuals suffering from limb loss. he is internationally recognized as a researcher and an independent expert for his unique expertise in bionic limbs. he approaches bionic solutions from a holistic perspective, by integrating the prosthetic biomechanics, clinical benefits, service delivery, and health economics. dr frossard has over 25 years of experience, both in academia and in private industries in australia, canada, and europe. he has collaborated with over 100 organizations worldwide. he is currently a professor of bionics at the griffith university, the director and chief scientist officer at yourresearchproject pty ltd, and adjunct professor at the queensland university of technology and the university of sunshine coast in australia. https://doi.org/10.33137/cpoj.v4i2.36365 https://www.who.int/choice/publications/p_2003_generalised_cea.pdf?ua=1dfid https://www.who.int/choice/publications/p_2003_generalised_cea.pdf?ua=1dfid all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 1 2024 research article sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1.42879 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i1.42879 1 sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1.42879 research article the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia sonune s.p, saha a*, joshi n.g, pathak s, bhadra p, goel g department of physical medicine and rehabilitation, all india institute of medical sciences, bhopal, india. introduction spinal cord injury (sci) is a complicated and incapacitating disorder that often leads to significant functional loss. india reports approximately 20,000 new cases of spinal cord injury (sci) each year, with a majority affecting young individuals from lower socioeconomic backgrounds.1 the prevalence of traumatic cervical spine fractures in western populations ranges from 4 to 17 cases per 100,000 person-years, with concurrent cervical spinal cord injuries (sci) occurring in 10–11% of cases.2 loss of hand function is one of the most notable areas of impairment for people with cervical sci, and it significantly affects their everyday activities and quality of life. the upper limb function, particularly hand grasp and release, is critical for performing essential tasks of daily living, social interaction, and vocational activities. consequently, restoring hand function is a primary objective following cervical spinal cord injury (sci). a study by anderson involving 347 individuals with open access abstract background: an individual experiencing tetraplegia faces functional limitations due to impaired hand function. the use of an affordable tenodesis wrist-hand orthosis (who) can enable finger flexion with active wrist extension, thereby enhancing the three-jaw chuck grasp and overall hand functionality. objectives: to assess hand function and satisfaction in patients with tetraplegia using a modified tenodesis wrist-hand orthosis (who), utilizing the duruöz hand index (dhi) and the orthotics and prosthetics user survey (opus) satisfaction with device and services subscales. methodology: the study was conducted at a tertiary care center in central india, enrolling patients with tetraplegia admitted to the department of physical medicine and rehabilitation. a modified tenodesis wristhand orthosis (who) was designed using low-temperature thermoplastic components. twenty-two individuals with a minimum wrist extensor power of grade 3/5 were included in the study. these patients were provided with the modified tenodesis who and underwent daily training sessions for a period of 2 weeks. duruöz hand index (dhi) scores were assessed at baseline, 6 weeks, and 12 weeks postenrolment. patient satisfaction was evaluated using the orthotics and prosthetics user’s survey (opus) satisfaction with device and services subscales. findings: the analysis of the dhi scores indicated a significant enhancement in functional abilities at both 6-week and 12-week follow-ups compared to the baseline assessment. notably, the most substantial progress at 6 weeks follow-up was observed in tasks such as buttoning a shirt, while significant improvement at the 12-week mark was noted in activities like turning a key in a lock. the median opus device satisfaction score was 50, corresponding to a rasch score of 68.8. additionally, the median opus satisfaction score for services stood at 46, with a rasch score of 72.7. patients expressed the highest satisfaction levels with the courteous demeanor of the staff, prompt scheduling of appointments, and accurate fitting of the orthosis. conclusion: the study findings indicate that the modified tenodesis who is an effective and satisfactory therapeutic device for improving hand function in patients with tetraplegia. the findings encourage further investigation and application of the modified tenodesis who in clinical practice. article info received: march 10, 2024 accepted: october 18, 2024 published: october 28, 2024 citation sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wristhand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1. 42879 keywords hand orthosis, wrist hand orthosis, spinal cord injury, tetraplegia, hand rehabilitation, orthosis * corresponding author: dr. anyesha saha, affiliation: department of physical medicine and rehabilitation, all india institute of medical sciences, saket nagar, bhopal (m.p.), india. e-mails: saha.anyesha@gmail.com; anyesha.sr2023@aiimsbhopal.edu.in orcid id: https://orcid.org/0009-0004-1574-0519 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 1, article no.8. 2024 https://doi.org/10.33137/cpoj.v7i1.42879 https://doi.org/10.33137/cpoj.v7i1.42879 https://doi.org/10.33137/cpoj.v7i1.42879 mailto:saha.anyesha@gmail.com mailto:anyesha.sr2023@aiimsbhopal.edu.in https://orcid.org/0009-0004-1574-0519 https://jps.library.utoronto.ca/index.php/cpoj/index 2 sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1.42879 canadian prosthetics & orthotics journal issn: 2561-987x modified tenodesis orthosis and hand function in patients with tetraplegia sonune et al., 2024 cervical-level sci found that 48.7% of patients prioritized regaining arm and hand function as the most impactful improvement for their quality of life, ranking it above sexual function, trunk stability, bowel and bladder control, and walking.3 despite advancements in medical management and rehabilitation, many individuals with sci still face significant challenges in regaining optimal hand function. tenodesis grasp and release is a biomechanical phenomenon that occurs with wrist extension and flexion and plays a crucial role in enabling functional grasp and release movements in individuals with sci. the tenodesis effect is used in patients with tetraplegia with innervated wrist extensor muscles but paralyzed finger and thumb flexor muscles. when the wrist is actively extended, passive tension of the extrinsic flexors of the thumb and fingers creates a grasp pattern between the thumb and fingers, resulting in a lateral pinch.4 active flexion of the wrist causes passive extension of the fingers. as the flexor digitorum profundus and superficialis are polyarticular muscles, complete extension of the wrist leads to about 20 degrees of flexion at the distal interphalangeal (dip) joints, 50 degrees of flexion at the proximal inter-phalangeal (pip) joints and 35 degrees of flexion at the metacarpophalangeal (mcp) joints in healthy individuals. gravity can be used to flex the wrist, which stretches the finger and thumb extensors and thus causes the hand to open. when the wrist is actively extended, passive stretch in the flexor digitorum profundus (fdp) and superficialis and flexor pollicis longus (fpl) effectively flexes the finger and thumb.5 the wrist extension torque (t1) produced by active wrist extension, leads to the development of a counter-clockwise torque at the mcp joints (t2). this torque at the mcp joints is balanced with the three-jaw chuck force (f) at the static pinch between the first 3 digits (figure 1).6 however, disruptions in tenodesis often result from altered muscle balance due to neurological deficits. this can lead to an inability to grasp objects effectively, diminishing a patient's autonomy and independence. to address this issue, orthoses have been explored to facilitate tenodesis grasp and improve hand function. the strength of the grasp depends on the amount of wrist extensor torque. a tenodesis wrist hand orthosis utilizes the natural tenodesis grasp as well as enhances this grasp by pulling the fingers towards the thumb using a connecting lever arm.7 the tenodesis wrist hand orthosis is a dynamic who that aims to enhance hand function by utilizing the natural mechanical advantage provided by intact wrist extensor muscles. the conventional tenodesis orthosis, also known as the flexor-hinge orthosis (fho), was made of metal. the plastic tenodesis who developed at rehabilitation institute of chicago (ric) was a modification of traditional high temperature thermoplastic who developed in 1960.7 while metals have been used in orthoses for many decades, the use of plastics in orthoses has now become more prevalent. plastics can be divided into two categories: thermoplastic and thermosetting. the modified tenodesis wrist hand orthosis used in this study is made of lowtemperature thermoplastic that becomes malleable at a temperature of less than 149 °c. unlike the high temperature thermoplastic ric tenodesis who, a negative cast is not required in fabricating this orthosis.8,9 thus, the fabrication of this modified tenodesis who requires less time and can be easily remoulded. traditional tenodesis whos have shown promising benefits in helping people with sci to perform grasp and release movements. however, modifications to the design and materials of the orthosis could enhance its effectiveness. these adjustments should consider factors such as comfort, flexibility, affordability, and the specific needs of each patient. some variations include ratchet-driven fhos,10 carbon dioxide-powered fhos,11 electric motordriven fhos, and cable-operated fhos.12 some modifications of fho for individuals with higher-level sci who lack voluntary wrist extension and have poor hand function include the ratchet fho, mckibben fho, electric motor-driven fho, and shoulder harness-driven fho.6 recent advancements in whos for patients with tetraplegia have led to improved functionality and usability. the sequential advancing flexion retention attachment (safra) was developed for patients with tetraplegia with a muscle power of 2/5 or 3/5 in the wrist extensors. the safra was integrated into a standard wrist-driven flexor hinge who with an adjustable tenodesis bar, eliminating the need for externally powered devices to achieve prehension.13 in south korea, a novel 3d-printed hand orthosis controlled by electromyography (emg) signals was tested on 10 patients, showing improvements in hand function.14 wearable robotic hand exoskeletons and gloves have also been developed for patients with tetraplegia.15,16 however, most of these modified whos were bulky and patients encountered issues with donning them. in the indian setting, there is a need for a more affordable and comfortable alternative to the tenodesis who that should be easy to manufacture. the use of thermoplastic materials that become pliable when heated can expedite the production of the orthosis, thereby reducing overall costs. we developed a modified form of tenodesis who in response to these demands. this observational study was aimed at determining how this alteration affects manual ability among people suffering from sci. https://doi.org/10.33137/cpoj.v7i1.42879 3 sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1.42879 canadian prosthetics & orthotics journal issn: 2561-987x modified tenodesis orthosis and hand function in patients with tetraplegia sonune et al., 2024 figure 1: biomechanics of a tenodesis who. a: flexion of the fingers with the extensor torque at the wrist; b: extension of the fingers with the flexor torque at the wrist; c: passive stretch of the finger flexors with active wrist extension. f: three-jaw chuck force; fdp: flexor digitorum profundus; fpl: flexor pollicis longus; mcp: metacarpophalangeal joint; t1: wrist extension torque; t2: metacarpophalangeal joint flexion torque; t3: flexion torque at the wrist; t4: extension torque at the mcp joint; w: wrist joint. methodology a prospective, single-arm observational study was conducted at a tertiary care center in central india to determine the effectiveness of a modified tenodesis wristhand orthosis (who) and assess patient satisfaction among individuals with spinal cord injury (sci). all patients with sci admitted to the physical medicine and rehabilitation department were assessed, and those meeting the inclusion criteria (table 1) were enrolled in the study through convenience sampling. a total of 35 individuals with sci were screened by the primary investigator, of whom 22 patients were enrolled in the study. the study was approved by the institutional ethics committee (institutional human ethics committee, aiims bhopal), and written informed consent was obtained from all participants before enrolment. the neurological level or completeness of the injury was not used as a criterion for inclusion or exclusion. the tenodesis action utilized by this modified tenodesis who requires active wrist extension. therefore, individuals with at least grade 3/5 strength in their wrist extensors irrespective of injury level or completeness, were considered potential candidates. each extremity of subjects was screened separately. if both sides lacked prehensile ability and had a power of 3/5 or more in wrist extensors, bilateral modified tenodesis who was prescribed. table 1: subject inclusion and exclusion criteria. inclusion criteria exclusion criteria 1) spinal cord injury with wrist extensor power of at least 3/5* 2) non-prehensile† 3) flexible wrist, metacarpophalangeal, and interphalangeal joints‡ 1) impaired cognitive function 2) recent fracture 3) complex regional pain syndrome 4) neuropathy affecting the upper limb (ulnar /median/radial neuropathy or brachial plexopathy) 5) arthritis in the wrist and joints of the fingers 6) acute burn injury to the wrist and hand 7) grade 2, 3, or 4 spasticity in the wrist or finger flexors or extensors¶ * power was graded based on the medical research council17; † non-prehensile was defined as the inability to seize or grasp an object, based on napier’s18 classification; ‡ full passive range of motion at the wrist with 70 degrees of extension and 80 degrees of flexion and at least 20 degrees of flexion at the dip, 50 degrees of flexion at the pip, and 35 degrees of flexion at the mcp joints; ¶ spasticity was assessed by the modified ashworth scale. for all patients, the modified tenodesis who was fabricated and fitted by an orthotist and prosthetist with 14 years of experience. a custom molded, comfortable, lightweight modified tenodesis who was designed using 2 mm low-temperature thermoplastic at a tertiary care rehabilitation center in central india, employing tenodesis grasp and biomechanical principles. figure 2: modified tenodesis wrist hand orthosis. the orthosis is made of low-temperature thermoplastic material and consists of four components. a: dorsal finger plate for digits 2 and 3; b: an elastic lacer that serves as the wrist component and facilitates the translation of tenodesis; c: distal palmar forearm component; d: short opponens component. as illustrated in figure 2, the modified tenodesis who is comprised of four components: segment (a) encompasses the middle and distal interphalangeal joints of the index and middle fingers; segment (b) is an elastic lacer that anchors t3 t4 w mcp t2 t1 w mcp active wrist extensors a b c taut fdp, fpl w f b c d a https://doi.org/10.33137/cpoj.v7i1.42879 4 sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1.42879 canadian prosthetics & orthotics journal issn: 2561-987x modified tenodesis orthosis and hand function in patients with tetraplegia sonune et al., 2024 to the finger and forearm components, and facilitates translation of tenodesis; segment (c) encompasses the palmer wrist and forearm; and segment (d) a short opponens component, maintains the proximal palmer arc and aligns the thumb in opposition. velcro® straps were used to secure the distal palmar forearm component, dorsal finger plate, and short opponens component, allowing adjustments for patient comfort. an elastic lacer, 2 mm thick, connected the volar surface of the dorsal finger plate to the volar surface of the distal palmar forearm component. the inclusion of the elastic lacer eliminated the need for actuating rod and artificial joint components as opposed to the conventional flexor hinge who, thus reducing the complexity of the orthosis.6 the weight of this who was approximately 80 grams (7585 grams), slightly lighter than the conventional who (approximately 113 grams) and heavier than the ric tenodesis who (42.5 grams).6 the orthosis was customized according to each individual’s shape and size, with a weight difference of 5-10 gram corresponding to the size variation. the cost of the orthosis is $4.50 usd, inclusive of material costs and labor charges, making it more economical than the ric tenodesis who, priced at around $39.95 usd.19 after applying the modified tenodesis who, participants were trained for 2 weeks regarding the proper usage of the orthosis, and specific task-oriented training was given to the patients. all participants required the help of the caregiver for donning and doffing. during this period, the accompanying family members/caregivers were also taught proper donning and doffing of the orthosis. proper care of the orthosis, avoidance of heat, cleaning with cold water, the need for the orthosis and the mechanism of use of the orthosis were explained to the individual. the participants were allowed to ask their queries regarding the orthosis throughout the sessions. figure 3: a patient with tetraplegia demonstrating use of the modified tenodesis who. a: wrist flexion; b: wrist extension and three-jaw chuck grasp; c: holding a pen. all the study participants received intensive training for 45 minutes per day for 2 weeks under a trained occupational therapist. the training included wrist extensor and flexor strengthening exercises, peg-socket activities, grasp and release activities (figure 3), and activities of daily living (adl) training in a simulated environment. the demographic and clinical data of the participants were documented. the outcome measures included the duruöz hand index (dhi) and the orthotics and prosthetics user’s survey (opus) satisfaction with device and services. the dhi is a valid tool for patients with tetraplegia, and it is used to assess hand function.20 the dhi is a likert scale that comprises 18 questions pertaining to hand activities that can be assessed based on the patient’s perspective. the opus satisfaction with device and services subjectively measured satisfaction with the device and the services using a 21-item survey.21 while assessing dhi, a few questions pertained to the use of a single hand, such as picking up a coin from the tabletop. these activities were assessed on the side on which the orthosis was prescribed. in those patients who were fitted with bilateral modified tenodesis who, the dominant hand was assessed for activities requiring a unilateral hand. the dominant hand was determined based on pre-injury hand dominance. outcome measures were recorded without the orthosis initially (week 0) and with the orthosis at 6 weeks and 12 weeks by the same treating physician at each followup. statistical analysis categorical variables such as gender, neurological level of injury (nli), and the side of use for the modified tenodesis who were presented as counts and percentages. continuous variables, including age and duration since injury, were expressed as means, standard deviations, and ranges. mean values were taken for individual items of the opus satisfaction with device and services, while a median value was taken for the total opus satisfaction with device and services score to represent the central tendency, as it is a likert type of scale. a wilcoxon signed-rank test was employed to assess the change in mean dhi scores of all 22 patients at 6 weeks and 12 weeks compared to baseline. statistical significance was set at p < 0.05 and analysis was conducted using spss version 21.0. results twenty-two individuals with tetraplegia were included in the study, of whom 18 were male and 4 were female. eleven subjects were fit with the modified tenodesis who on the right upper extremity, whereas 6 subjects were fit with the device on the left upper extremity and 5 were fit with the device on both upper extremities (table 2). a b c https://doi.org/10.33137/cpoj.v7i1.42879 5 sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1.42879 canadian prosthetics & orthotics journal issn: 2561-987x modified tenodesis orthosis and hand function in patients with tetraplegia sonune et al., 2024 table 2: subjects demographic data. the dhi score at admission was collected as the baseline. the mean ± standard deviation for dhi at baseline (no orthosis) was 83.4 ± 3.72, while it was 75.5 ± 5.12 at 6 weeks and 68.9 ± 6.92 at 12 weeks with the modified tenodesis who, respectively. compared to the baseline, there was a significant improvement in dhi at 6 weeks (p<0.001) and 12 weeks (p<0.001) with the use of the modified tenodesis who (figure 4). figure 4: duruoz hand index (dhi). *p<0.001 for difference in mean dhi scores at 0 and 6 weeks; ** p<0.001 for difference in mean dhi scores at 0 and 12 weeks. the total dhi score (out of 90) was calculated for all 18 items, while each item was scored from 0-5 (0: yes, without difficulty; 1: yes, with a little difficulty; 3: yes, with much difficulty; 4: nearly impossible to do; 5: impossible). among all the items on the dhi scale, the activity performed with the least difficulty while using the modified tenodesis who was pricking items with a fork. significant improvement (table 3) was perceived in performing all functional activities of the dhi scale using the modified tenodesis who at 12 weeks as compared to baseline except unscrewing the lid of a jar and peeling a fruit. the most significant functional improvement at 6 weeks compared to baseline was observed in buttoning a shirt (p=0.000), whereas the greatest enhancement was noted in turning a key in a lock at 12 weeks (p=0.000) compared to baseline (table 3). the median for the opus device satisfaction score was 50, pertaining to a rasch score of 68.8 and the median for the opus satisfaction for services score was 46, with a rasch score of 72.7. among the subitems of the opus device satisfaction, the maximum satisfaction was experienced with respect to the fit of the orthosis, while the least satisfaction was experienced with donning the orthosis (figure 5a) all patients expressed the highest satisfaction with the behavior of staff (i.e., courteous and respectful) and expressed the lowest satisfaction with their own decisionmaking process regarding the orthosis (figure 5b). discussion the results of this prospective observational study demonstrated significant improvements in hand function among patients with sci who utilized the modified tenodesis who. the effectiveness of this modified tenodesis who in enhancing hand function is demonstrated by a significant improvement in the dhi scores after 6 and 12 weeks compared to baseline. the notable enhancements in activities such as opening a lock and buttoning a shirt underscore the importance of the modified tenodesis orthosis in improving pinch grip. this orthosis enables skillful placement of objects between the thumb and fingers, facilitating the manipulation of small items like keys, forks, buttons, and pens, ultimately enhancing overall hand function. however, the omission of the digits 4 and 5 from the modified who may have contributed to limitations in spherical and cylindrical grasp as these types of grasp patterns typically require engagement of all five digits. thus, there were limited gains in activities such as unscrewing a jar, holding a bowl, or lifting a bottle. hence, a limitation of the orthosis is that it restricts grasping that requires all five digits, likely necessitating the user to employ alternative movements to compensate for this limitation. similar results with improvements in hand function using various designs of a tenodesis who have been previously seen. in a study by meyer et al., the application of a flexor hinge who enabled a 43-year-old teacher with a complete c6-level sci to return to work and perform domestic activities, such as cooking.22 in the same study, another woman who had a c6item number percentage (%) gender male 18 81.8 female 4 18.2 *nli: neurological level of injury c2 1 4.5 c4 3 13.7 c5 11 50.0 c6 5 22.7 c7 2 9.0 modified tenodesis who side right 11 50.0 left 6 27.3 bilateral 5 22.7 dominant 12 54.6 non-dominant 5 22.7 dominant and nondominant 5 22.7 mean age (range) 36.7 (20-64) years mean duration since injury (range) 9.8 (3-34) months duruöz hand index baseline (0 week) 6 weeks 12 weeks https://doi.org/10.33137/cpoj.v7i1.42879 6 sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1.42879 canadian prosthetics & orthotics journal issn: 2561-987x modified tenodesis orthosis and hand function in patients with tetraplegia sonune et al., 2024 level complete lesion was able to return to the farm and perform activities like cooking, sewing, and knitting with bilateral flexor-hinge who. a modified wrist-driven flexor hinge who with a dial lock, allowing the orthosis to function at different ranges of motion at the wrist joint, was studied by rout et al.23 they observed that without the orthosis, participants were able to lift 50 grams of weight, while with the orthosis, there was an increase in the ability to lift the weight up to 300 grams. in our study, significant improvement in the ability to raise a full bottle and plate full of food indicates an increased ability to lift weight, but the improvement in such activities at 6 weeks was not significant. in a study by yoo et al. a 3d-printed myoelectric wrist hand orthosis was assessed for improvement in hand function of persons with sci,14 representing one of the latest advancements for patients with tetraplegia. their findings also demonstrated improvement in eating with the 3dprinted orthosis, although there were no significant gains in dressing or grooming abilities. batra et al. compared the efficacy of biofeedback to use of a tenodesis who in persons with c5-c6 sci.24 a significant improvement in the ability to lift weights and in the functional independence measure (fim) was achieved in both the groups, but biofeedback was found to be more effective. based on these promising findings, biofeedback could potentially be used in conjunction with the use of the modified tenodesis who in future studies to investigate its efficacy in facilitating clinical outcomes. assessment using the opus satisfaction with device and services in our study revealed that participants expressed high satisfaction levels with the courteous behavior of staff, prompt appointment scheduling, and appropriate fit of the orthosis. the thermoplastic material's easy moldability directly over the skin ensured an appropriate fit, and patients reported satisfaction with training and ease of use. however, a notable area of dissatisfaction was experienced during the donning and doffing of the orthosis. despite having fewer components compared to traditional flexor hinge orthosis, patients with impaired hand function often require assistance from caregivers due to weakness in both upper extremities, indicating a need for further modifications to improve independent donning and doffing capabilities. the results of this study hold significant clinical implications for patients with sci undergoing hand function rehabilitation, potentially enhancing their participation in both personal and professional activities. furthermore, investigating the long-term effects of the modified tenodesis who on hand function and exploring its applicability across various levels and severities of sci are avenues for further research. additionally, incorporating qualitative measures to capture participants’ perceptions and experiences with the who could provide valuable insights into its acceptability and usability. table 3: mean and standard deviation (sd) of each dhi subitem at 6 weeks and 12 weeks as compared to the baseline. dhi mean ± sd at 0 week dhi mean ± sd at 6 weeks dhi mean ± sd at 12 weeks p* p** hold a bowl 4.72 ± 0.63 4.64 ± 0.66 4.23 ± 0.92 0.157 0.009 seize a full bottle and raise it 4.90 ± 0.29 4.77 ± 0.43 4.32 ± 0.72 0.083 0.004 hold a plate full of food 4.72 ± 0.55 4.59 ± 0.59 4.14 ± 0.89 0.083 0.006 pour liquid from a bottle into a glass 4.86 ± 0.35 4.68 ± 0.65 4.32 ± 0.78 0.102 0.006 unscrew the lid from a jar opened before 4.72 ± 0.70 4.68 ± 0.72 4.59 ± 0.80 0.317 0.180 cut meat with a knife 4.40 ± 0.91 3.55 ± 0.60 3.41 ± 0.67 0.000 0.000 prick things well with a fork 3.77 ± 0.81 2.73 ± 0.46 2.45 ± 0.51 0.002 0.000 peel fruit 4.90 ± 0.29 4.91 ± 0.29 4.68 ± 0.57 1.000 0.059 button your shirt 4.50 ± 0.86 3.32 ± 0.89 3.05 ± 0.95 0.000 0.000 open and close a zipper 4.27 ± 0.83 3.86 ± 0.94 3.59 ± 0.67 0.003 0.000 squeeze a new tube of toothpaste 4.50 ± 0.86 3.95 ± 0.90 3.64 ± 0.66 0.006 0.000 hold a toothbrush efficiently 4.72 ± 0.46 4.36 ± 0.79 3.32 ± 0.84 0.023 0.000 write a short sentence with a pencil or ordinary pen 4.54 ± 0.67 3.86 ± 0.83 3.27 ± 0.83 0.004 0.000 write a letter with a pencil or ordinary pen 4.90 ± 0.29 4.32 ± 0.84 3.77 ± 0.81 0.009 0.000 turn around doorknob 4.72 ± 0.63 4.68 ± 0.72 4.41 ± 0.80 0.317 0.020 cut a piece of paper with scissors 4.90 ± 0.43 4.86 ± 0.47 4.73 ± 0.55 0.317 0.046 pick up coins from a tabletop 4.31 ± 0.84 3.95 ± 0.95 3.59 ± 0.73 0.011 0.000 turn a key in a lock 4.90 ± 0.29 3.82 ± 0.59 3.36 ± 0.49 0.000 0.000 p* = p-value between means at 0 and 6 weeks. p**= p value between means at 0 and 12 weeks. the p-values are calculated using the wilcoxon signed-rank test. https://doi.org/10.33137/cpoj.v7i1.42879 7 sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1.42879 canadian prosthetics & orthotics journal issn: 2561-987x modified tenodesis orthosis and hand function in patients with tetraplegia sonune et al., 2024 limitations several limitations warrant consideration. the lack of a control group precludes definitive causal conclusions regarding the efficacy of this wrist hand orthosis. additionally, the relatively short intervention period may have influenced the magnitude of the observed improvements. future studies could mitigate these limitations by incorporating randomized controlled designs and extended intervention durations. conclusion in conclusion, the results of this observational study provided evidence supporting the potential efficacy of a modified tenodesis who in improving hand function among patients with sci, particularly in activities such as eating with a fork, buttoning a shirt, locking with a key, holding a toothbrush, and writing with a pen. the observed enhancements in functional independence suggest that this intervention could significantly contribute to hand rehabilitation strategies for individuals with sci. the participants had maximum satisfaction with the behavior of the staff, prompt appointments and appropriate fit of the device, while they were most concerned with donning difficulty. the findings encourage further investigation and application of the modified tenodesis who in clinical practice. acknowledgements the authors would like to express their gratitude to the study participants, whose enthusiastic involvement made this work possible. declaration of conflicting interests the authors disclose that they have no personal or financial ties to any companies or people that could have impacted their research. authors contribution • swapnil p. sonune: conceptualization, original drafting, writing, data collection, statistical analysis. • anyesha saha: writing, data collection, statistical analysis, revising the manuscript. • joshi niravkumar ganpatram: writing, data collection, revising the manuscript. • smita pathak: designing orthosis. • prasenjit bhadra: writing, data collection, revising the manuscript. figure 5: opus satisfaction scores. a: satisfaction for device; b: satisfaction for services. the response to each item was scored as follows: 5= strongly agree; 4= agree; 3= neither; agree nor disagree; 2= disagree; 1= strongly disagree. 0 1 2 3 4 5 6 my prosthesis/orthosis fits well the weight of my prosthesis/orthosis is managable my prosthesis/orthosis is comfortable throughout the day it is easy to put on my prosthesis/orthosis my prosthesis/orthosis looks good my prosthesis/orthosis is durable my clothes are free of wear and tear from my prosthesis/orthosis my skin is free of abrasions and irritations my prosthesis/orthosis is pain free to wear i can afford the out-of-pocket expenses to purchase and maintainmy prosthesis /orthosis i can afford to repair or replace my prosthesis/ orthosis as soon as needed mean score mean score of subitems of opus satisfaction for device 0 1 2 3 4 5 6 i received an appointment with a prosthetist/orthotist within a reasonable amount of time i was shown the proper level of courtesy and respect by the staff i waited a reasonable amount of time to be seen clinic staff fully informed me about the equipment choices the prosthetist/orthotist gave me the opportunity to express my concerns regarding the equipment the prosthetist/orthotist was responsive to my concerns and questions i am satisfied with the training i received in the use and maintenance of my prosthesis/ orthosis the prosthetist / orthotist discussed problems i might encounter with the equipment the staff coordinated their services with my therapists and doctors i was a partner in decision making with clinic staff regarding my care and equipment mean score mean score of subitems of opus satisfaction for services a b https://doi.org/10.33137/cpoj.v7i1.42879 8 sonune s.p, saha a, joshi n.g, pathak s, bhadra p, goel g. the effect of a modified tenodesis wrist-hand orthosis on hand function in patients with tetraplegia. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.8. https://doi.org/10.33137/cpoj.v7i1.42879 canadian prosthetics & orthotics journal issn: 2561-987x modified tenodesis orthosis and hand function in patients with tetraplegia sonune et al., 2024 • gaurav goel: writing, data collection, revising the manuscript. all authors reviewed the manuscript and approved the final version. sources of support there was no funding for this research. references 1.singh r, dhankar ss, rohilla r. quality of life of people with spinal cord injury in northern india. int j rehabil res. 2008;31(3):247-51. doi: 10.1097/mrr.0b013e3282fb7d25 2.utheim nc, helseth e, stroem m, rydning p, mejlænderevjensvold m, glott t, et al. epidemiology of traumatic cervical spinal fractures in a general norwegian population. inj epidemiol. 2022;9(1):10. doi: 10.1186/s40621-022-00374-w 3.anderson kd. targeting recovery: priorities of the spinal cordinjured population. j neurotrauma. 2004;21(10):1371-83. doi: 10.1089/neu.2004.21.1371 4.jung hy, lee j, shin hi. the natural course 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[cited 2024, may 11]. available from: https://www.sralab.org/sites/default/files/201703/opus%20scoring%20guide.pdf. 22.meyer cm, shrosbree rd, abrahams dl. a method of rehabilitating the c6 tetraplegic hand. paraplegia. 1979;17(2):1705. doi: 10.1038/sc.1979.35 23.rout, bapin k. and c. s. prasanth. modified wrist driven flexor hinge splint for c6 quadriplegic patients. int j health res. 2020; 260-263. 24.batra v, batra m. to compare the efficacy of biofeedback over tenodesis splint for functional tenodesis training in s.c.i. patients with level c5-6. indian j occup ther. 2008; vol xl (3); 75-79. https://aiota.org/temp/ijotpdf/ibat08i3p75.pdf https://doi.org/10.33137/cpoj.v7i1.42879 https://www.oandplibrary.org/op/1965_02_137.asp http://www.ncmedical.com/products/tenodesis-thermoplastic-splint-kit_685.html http://www.ncmedical.com/products/tenodesis-thermoplastic-splint-kit_685.html https://www.sralab.org/sites/default/files/2017-03/opus%20scoring%20guide.pdf https://www.sralab.org/sites/default/files/2017-03/opus%20scoring%20guide.pdf https://aiota.org/temp/ijotpdf/ibat08i3p75.pdf all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 research article baghbanbashi a, farahmand b, azadinia f, jalali m. evaluation of user’s satisfaction with orthotic and prosthetic devices and services in orthotics and prosthetics center of iran university of medical sciences. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.10. https://doi.org/10.33137/cpoj.v5i1.37981 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.37981 1 baghbanbashi a, farahmand b, azadinia f, jalali m. evaluation of user’s satisfaction with orthotic and prosthetic devices and services in orthotics and prosthetics center of iran university of medical sciences. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.10. https://doi.org/10.33137/cpoj.v5i1.37981 research article evaluation of user’s satisfaction with orthotic and prosthetic devices and services in orthotics and prosthetics center of iran university of medical sciences baghbanbashi a, farahmand b*, azadinia f, jalali m rehabilitation research center, orthotics and prosthetics department, school of rehabilitation sciences, iran university of medical sciences, tehran, iran. introduction according to the world health organization (who) estimate in 2017 around 35–40 million people require prosthetic or orthotic services.1 based on a report published by the state welfare organization of iran, which supports the underprivileged, this organization provided orthotics and prosthetics services for about 47000 people between 2019 to 2021 in iran.2 this is a small portion of those who need orthotics and prosthetics services in iran. many people receive services from rehabilitation centers of red crescent society of iran (provide rehabilitation services to more than 70000 people per year)3 or from private sector. the need for the evaluation of orthotic and prosthetic (o&p) services has recently increased.4 the assessment of the device and service quality is a prerequisite of the accreditation of the o&p centers.5 regardless of the clinical practice ethics, open access volume 5, issue 1, article no.10. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: the number of patients receiving orthotics and prosthetic services is increasing globally. a way to investigate patients’ insight about services provided to them is to evaluate their satisfaction with the received services. furthermore, incorporating patients’ preferences into practice is an inseparable part of evidence-based practice. applying such information in practice can contribute to the enhancement of the quality of services, the effectiveness of therapeutic interventions, and finally, the economic growth of service centers. objective(s): to evaluate patients’ satisfaction with the orthotic and prosthetic devices and services provided by the orthotics and prosthetics clinic of iran university of medical sciences. methodology: in this study, 173 people referring to the orthotics and prosthetics clinic of iran university of medical sciences were recruited, and their satisfaction level was examined using the orthotics and prosthetics users’ survey questionnaire (opus) through a phone interview. findings: concerning the devices, the mean value of total satisfaction score was 74:00±19.80 and the highest score belonged to no wear or rupture of the clothes with their devices (mean value = 4.76±0.84). in terms of services, the mean value of total satisfaction score was 72.12 ± 15.90 with the highest score belonging to the politeness of the clinic staff (mean value = 4.92±0.57). when the time point from receiving service was taken into account, the patients who received the service for less than a year showed higher satisfaction level with the service (p=0.024). although satisfaction with the device was slightly higher among the participants who used the devices for more than a year, no significant difference was observed between the two groups in terms of device satisfaction. conclusions: the overall satisfaction level from the devices and services was relatively high. however, the satisfaction level with the costs and coordination of the staff with the physicians showed a decline. article info received: february 19, 2022 accepted: june 29, 2022 published: july 17, 2022 citation baghbanbashi a, farahmand b, azadinia f, jalali m. evaluation of user’s satisfaction with orthotic and prosthetic devices and services in orthotics and prosthetics center of iran university of medical sciences. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.10. https://doi.org/10.33137/cpoj.v5i1.3 7981 keywords orthosis, prosthesis, satisfaction, survey, orthotics, prosthetics, rehabilitation * corresponding author behshid farahmand, phd rehabilitation research center, orthotics and prosthetics department, school of rehabilitation sciences, iran university of medical sciences, tehran, iran. email: farahmand.b@iums.ac.ir orcid id: https://orcid.org/0000-0002-1756-8335 https://doi.org/10.33137/cpoj.v5i1.37981 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i1.37981 https://doi.org/10.33137/cpoj.v5i1.37981 mailto:farahmand.b@iums.ac.ir https://orcid.org/0000-0002-1756-8335 2 baghbanbashi a, farahmand b, azadinia f, jalali m. evaluation of user’s satisfaction with orthotic and prosthetic devices and services in orthotics and prosthetics center of iran university of medical sciences. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.10. https://doi.org/10.33137/cpoj.v5i1.37981 issn: 2561-987x evaluation of user’s satisfaction with orthotic and prosthetic devices and services baghbanbashi et al., 2022 cpoj outcome assessment can lead to the economic growth of the o&p facilities, as identification of the customers' needs and willingness to satisfy them can preserve the customers for the organization.6 evidence has shown a close relationship between customers’ satisfaction and the profitability of the organization.7 in this way, most organizations are interested in evaluating the quality of their service to improve their customers’ satisfaction and thereby survive the organization.8 the patient is a key factor in such assessments.9 satisfaction with the services is a proper index for estimating the quality of services and their presentation to the clients, which helps adaptation of the service or product to the needs and expectations of the clients. satisfaction is defined as the experience of the client after receiving a product or service.10 in other words, customer satisfaction and desirability of the product or service are related to the fulfillment of his/her needs. satisfaction assessment in health management not only provides the information required to improve the health care services but also may indirectly improve the health state of individuals due to its positive psychological and mental effects. patients' satisfaction with health services is recognized by the world health organization (who) as one of the five indicators of service quality.11,12 satisfaction assessment in the o&p field is more difficult than other parts of the health system because health practitioners, deliver wearable devices such as orthoses, prostheses, insoles, and medical shoes to the patients in addition to providing services such as patients assessment and training.10,13 this means that the satisfaction assessment should include two aspects: the service assessment and the quality assessment of the delivered device.10 deruyter et al.14 defined patients’ satisfaction along with other factors such as clinical outcomes, functional status, quality of life, and cost as key indicators in the field of assistive devices. moreover, achieving more favorable clinical outcomes requires the patient's adherence to the use of the prescribed orthoses or prostheses.15,16 the patient’s satisfaction is a factor playing a role in his/her adherence to the treatment.17 some researchers believe that esthetic factors and convenience, as well as economic status and social issues, affect the level of satisfaction with an orthosis or a prosthesis and can improve patients’ adherence to the orthotic/prosthetic intervention.18 in iran, the results of a survey on satisfaction with o&p facilities in a private clinic in 2012 showed that despite dissatisfaction with the appearance of device and its durability and delivery process, the patients expressed a high level of satisfaction with the fitness of their device.19 various instruments and methods have been developed to measure the satisfaction of the users of orthotic and prosthetic devices among which, modified servqual questionnaire,4 quebec user evaluation of satisfaction with assistive technology,20 the trinity amputation and prosthesis experience scales (tapes),21 and orthotics and prosthetics users survey (opus)22 can be mentioned. the opus questionnaire designed by heinemann et al.22 for estimating the satisfaction level of the users of orthotic and prosthetic devices and services has gained high validity and reliability. assessing the satisfaction level of users and identifying the factors that lead to dissatisfaction along with its possible solutions can provide valuable information to improve the quality of devices and services provided by o&p centers, which in turn can increase the client’s satisfaction, improve clients' functional status, and finally advance the economic growth of these centers. furthermore, as mentioned earlier, device and service quality assessment is a prerequisite in the accreditation of o&p facilities. despite the significance of user satisfaction in the treatment success and economic growth of service provider centers, a limited number of studies have addressed this issue in the o&p field.10,13,19,23,24 since accreditation is the responsibility of national universities of medical sciences of each province, the present study was conducted to investigate the satisfaction of patients referred to the o&p center of iran university of medical sciences as an educational and therapy center. methodology the present study is descriptive-analytical research whose protocol was approved by the ethics committee at iran university of medical sciences (iumc). a total of 173 volunteers were selected among the people referring to the o&p center at the rehabilitation school of iran university of medical sciences through a convenience sampling method. non-electronic (paper-based) data including patients' contact information are stored in the o & p center. patients' contact information based on their permission were transmitted to the main investigator. the inclusion criterion was a history of at least 3 months of using orthoses or prostheses that were made and prescribed in the o&p center of the rehabilitation school. subjects who were unable to respond to the questionnaire or phone interview due to cognitive or speech problems were excluded from the study. the origin version of opus questionnaire (satisfaction module) answered through phone interviews was used to assess the users' satisfaction with the o&p devices and services.22 if the user was younger than ten, parents were contacted. the opus questionnaire includes 5 domains: lower extremity functional status (lefs), upper extremity functional status (uefs), client satisfaction with devices (csd), client satisfaction with services (css), and healthrelated quality of life (hrqol). the validity and reliability of this questionnaire were confirmed in persian (cronbach's https://doi.org/10.33137/cpoj.v5i1.37981 3 baghbanbashi a, farahmand b, azadinia f, jalali m. evaluation of user’s satisfaction with orthotic and prosthetic devices and services in orthotics and prosthetics center of iran university of medical sciences. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.10. https://doi.org/10.33137/cpoj.v5i1.37981 issn: 2561-987x evaluation of user’s satisfaction with orthotic and prosthetic devices and services baghbanbashi et al., 2022 cpoj alpha coefficient of 0.71 and 0.89 for device and service satisfaction, respectively).25 the satisfaction domain of the opus questionnaire is composed of 21 questions, 11 of which are related to the evaluation of "satisfaction with the received device, i.e., orthoses and prostheses" and the other 10 items are related to the evaluation of "service satisfaction". the section related to "device" in the opus questionnaire explores various aspects of the patients’ satisfaction including proper fitting, weight, durability, maintenance, easy to put on, appearance, comfort of use, wear, and tear of clothing, painfree when wearing the device, skin irritation and affordability of device repair and replacement. the service section also assesses the patient’s satisfaction with the level of courtesy and respect of the center staff, staff response to concerns and questions of the participants, opportunities for the patient to express their concerns, training how to use the device, waiting time, patient involvement in the decision-making process, discussion of problems, receiving an appointment within a reasonable time, question the explanations to choose the most appropriate device, and coordination between staff of the center and therapists with the doctors. the scoring guideline was used to score the response to each question (5=strongly agree, 4= agree, 3=neither agree nor disagree, 2=disagree,1=strongly disagree). "satisfaction with device" score was the sum of the scores for items 1-11 (11 – 55). "satisfaction with services" score was the sum of the scores for items 12-21 (10 – 50). higher scores indicate better outcomes for both measures. the provided table was used to convert the raw scores to rasch measures (0100).26 a demographic questionnaire was also completed which collected information on name, surname, age, gender, level of education, occupation, involved organ, involved side, cause of receiving the device, year of receiving the service, duration of device use, and the treatment costs (%) covered by insurance companies. the de-identified data has been stored in spss format and if requested, excel format can be transformed. this data can be requested from the o & p department via corresponding author. statistical analysis: to analyze the data, spss software (version 22) was used. shapiro-wilk test was used to ensure the normal distribution of overall satisfaction scores. frequency was used to describe qualitative variables while mean and standard deviation were employed for quantitative variables. kruskalwallis test was adopted to compare the satisfaction scores of the device and services between the age groups. a mann-whitney test was used to compare the two groups of men and women, as well as the groups who used the device for 3 months to a year and those who used the device for more than a year. the statistical significance level was set at 0.05. results men make up 58% of the study population whereas the percentage of women was 42%, the minimum and maximum age of clients were 4 and 85 years, respectively (table 1). the mean and standard deviation of the users’ age was 32.1± 23.5 years. most devices received by the clients were insoles and medical shoes (145 cases). table 1: demographic characteristics and device types. satisfaction with device: the findings of this study indicated that in the device satisfaction section, the lowest level of satisfaction was related to the affordability to repair or replace the prosthesis or orthosis, as well as purchasing or maintaining them (table 2). the higher satisfaction rate was for the item concerned with no wear or rupture of the clothes by the received device. in the present study, the overall satisfaction with the device was 74.00 ± 19.80. according to the results of a kruskal-wallis test, satisfaction with the device (h (3) =0.97, p=0.808) did not exhibit a significant difference between age groups. a mann-whitney u test revealed no significant difference in the satisfaction level of males and females with a device (u=3132.0, z=-1.61, p=.107). satisfaction with the device did not show a significant difference when participants were classified into two groups in terms of duration of using the device (3 months to 1 year and more than one year), albeit those who used the device for more than one year expressed higher satisfaction (u=1921, z=-1.52, p=.128). satisfaction with service: the satisfaction with the services summed up to 72.12 ±15.89. in terms of service satisfaction, the highest n gender 100 males, 73 females age (year) <10 33 10-34 63 35-64 59 >65 18 device types footwear / insole 145 (flatfoot/cavus/heel pain/corn&callus/clubfoot/leg length discrepancy/diabetes) lower limb orthosis 20 (stroke/cp/neuropathy/orthopedic) hallux valgus splint 8 https://doi.org/10.33137/cpoj.v5i1.37981 4 baghbanbashi a, farahmand b, azadinia f, jalali m. evaluation of user’s satisfaction with orthotic and prosthetic devices and services in orthotics and prosthetics center of iran university of medical sciences. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.10. https://doi.org/10.33137/cpoj.v5i1.37981 issn: 2561-987x evaluation of user’s satisfaction with orthotic and prosthetic devices and services baghbanbashi et al., 2022 cpoj satisfaction was related to the courtesy and respectful behavior of the employees of the complex (4.92± 0.57). the lowest level of satisfaction from services was for the coordination of clinic staff with other treatment staff (1.56 ± 2.11). according to the results of a kruskal-wallis test, satisfaction with services (h (3) =4.24, p=0.237) did not exhibit a significant difference between age groups. a mann-whitney u test revealed no significant difference in the satisfaction level of males and females with services (u=3594.0, z=-0.18, p=0.856). in terms of duration of the device use, service satisfaction was higher in the group that received the service for less than a year (table 3). the two groups showed a significant difference in terms of service satisfaction (u=1756.5, z=-2.25, p=0.024). table 2: mean, standard deviation and range of items and (device and service) total scores of the opus. table 3: comparison of level of satisfaction with device and with service between and among groups based on gender, age, and device use time. satisfaction with service satisfaction with device group p=0.237 69.5 ± 14.43 74.59 ± 15.86 72.10 ± 17.68 68.35 ± 11.23 p=0.808 73.76 ± 20.71 72.45 ± 19.48 74.45 ± 19.47 78.37 ± 21.23 age group <10 10-34 35-64 >65 p=0.024* 79.86 ± 18.35 70.30 ± 14.74 p=0.128 69.74 ± 20.05 75.06 ± 19.66 device use time 3months-1year >1 year p=0.856 72.33 ± 16.39 71.97 ± 15.59 p=0.107 71.26 ± 20.42 75.99 ± 19.18 gender female male * significantly different discussion despite the significance of user satisfaction in the treatment success and economic growth of service provider centers, a limited number of studies have addressed this issue in the o&p field.10,13,19,23,24 in this context, the present study aimed to assess the satisfaction of the clients of the o&p center of iran university of medical sciences through opus questionnaire. satisfaction with device: the findings of this study showed that in the device satisfaction section, the lowest level of satisfaction was related to the affordability to repair or replace the prosthesis or orthosis, followed by the affordability to purchase, and maintain them. the o&p center of the rehabilitation school is an educational-clinical center and only the cost of materials and consumable parts are paid by the clients, so patients could obtain orthoses and prostheses much cheaper than private centers. despite this privilege the "affordability" showed to be the main source of lower satisfaction in this survey. this survey was completed between 2015 and 2018. based on the minimum monthly wage and benefits for a family with two children set by the government through these years, the cost of receiving lower limb orthoses in iums o&p center would be approximately 9%-12.4% of the minimum wage for foot orthoses, 19.7%38.2% for medical shoes and 23.6%-36.5% for lower limb orthoses. financial issues are one of the challenges in providing o&p services. poor coverage of basic and supplementary insurance services makes the o&p users pay most of the costs out of pocket. only a couple of prostheses and orthoses are covered by basic health insurance companies. furthermore, although the general conditions of supplementary insurance services (private or group health) for p&o is better, many people find the insurance premiums high to afford. however, most of these companies set a ceiling to reimburse costs which may restrict the ability of patients for purchasing the services. mean ± sd maximum minimum 4.62 ± 0.93 5 0 fits well 4.42 ± 1.08 5 0 manageable weight 4.36 ± 1.14 5 0 comfortable 4.51 ± 1.04 5 0 easy to put on 4.63 ± 0.84 5 1 looks good 4.72 ± 0.80 5 1 durable 4.76 ± 0.84 5 0 wear and tear clothes 4.55 ± 1.04 5 1 skin abrasion and irritation 4.49 ± 1.05 5 1 pain free 3.95 ± 1.57 5 0 afford purchase 3.95 ± 1.54 5 0 afford repairs 4.77 ± 0.92 5 0 appointment in reasonable time 4.92 ± 0.57 5 0 showing courtesy 4.85 ± 0.54 5 2 wait reasonable time 4.88 ± 0.53 5 1 informed about choices 4.86 ± 0.58 5 0 opportunity to express concerns 4.87 ± 0.53 5 0 responsive to concerns 4.87 ± 0.52 5 1 training for use and maintenance 4.83 ± 0.66 5 1 discussion about problems 1.56 ± 2.11 5 0 coordination with therapist 4.46 ± 1.44 5 0 participation in decision making 74.00 ± 19.80 100 33.06 satisfaction with device ± 15.8972.12 100 37.72 satisfaction with service https://doi.org/10.33137/cpoj.v5i1.37981 5 baghbanbashi a, farahmand b, azadinia f, jalali m. evaluation of user’s satisfaction with orthotic and prosthetic devices and services in orthotics and prosthetics center of iran university of medical sciences. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.10. https://doi.org/10.33137/cpoj.v5i1.37981 issn: 2561-987x evaluation of user’s satisfaction with orthotic and prosthetic devices and services baghbanbashi et al., 2022 cpoj the most effective solution would be the boosted coverage of o&p services by basic insurance units.27 the policymakers of the health system should remove this barrier by enacting the necessary regulations. iranian association of orthotics and prosthetics which is the main actor in this field is trying hard to convince them of the benefits of this policy. in the study by alsancak et al.28 and ghoseiri et al.,19 the highest level of dissatisfaction was related to the appearance and esthetic aspects of the device. in the mentioned studies some of the participants received upper limb orthoses and prostheses. as upper limb orthosis and prostheses are more visible, it is logical that the appearance and aesthetic aspect of the device be the main concern and priority of participants. in the present study, insoles and medical shoes accounted for about 83% of the prescribed devices. although desirable appearance is an important factor in patients’ adherence to o&p treatments, in the case of insoles and footwear, the comfort of the device, its weight, the quality of the material, and its effect on reducing symptoms may play more decisive roles in patients’ satisfaction. based on the findings of the present study, the average satisfaction with the comfort of orthosis was 4.36 ± 1.14, which is higher than the report of ghoseiri et al.19 (2.40 ± 1.00). moreover, in the present study, the mean score of pain-free wearing of orthoses was 4.49 ± 1.05, reflecting the effectiveness of the devices prescribed in this center. however, in ghoseiri et al.19 and hoda et al.23 studies, this rate was 2.1± 0.9 and 3.39, respectively. in our study, the overall satisfaction of the device was 74.00 ±19.80, higher than the mentioned two studies (ghoseiri et al.19: 46.6±15.2; and hoda et al.23: 45.94 ± 11.62). however, in the research conducted by bosmans et al.,24 the satisfaction rate was 78% among the clients of 15 o & p facilities in the netherlands. routhier et al.29 only assessed satisfaction with the myoelectric prosthesis in 18 patients with upper limb amputation which resulted in the satisfaction rate of 80%. it should be noted that deformity or specific neuromusculoskeletal conditions of clients may cause different psychological challenges, affecting their satisfaction with orthosis/prosthetic treatments. satisfaction with service: concerning service satisfaction, the mean total satisfaction score in this study was 72.10 ± 17.68, higher than hoda et al.23 (65.77± 22.00) and ghoseiri et al.19 (59.70 ± 12.00). the highest level of satisfaction was related to the politeness and proper respect of the employees of the complex with an average value of 4.92 ± 0.57. similarly, hoda et al.23 and ghoseiri et al.19 reported this parameter with the highest level of satisfaction with respective average values of 74.40±4.00 and 3.30±0.70. the lowest level of satisfaction in the field of services in the present study was related to the coordination of clinic staff with other treatment staff with an average value of 1.56 ± 2.11, indicating the need for better communication and cooperation between rehabilitation physicians, physical therapists, and orthotists to achieve a successful rehabilitation treatment. the current study also revealed a higher level of satisfaction among the users who received services during the past year compared to those who received services for more than a year. conclusion the results of the present study indicated relatively high satisfaction with both the quality of orthopedic devices and services among patients referred to the o&p center of iran university of medical sciences. however, when the costs associated with the device and the coordination of clinic staff with therapists and physicians were considered the satisfaction level declined. assessment of clients' satisfaction, as an approach to obtain their insights, can be a prominent part of evidence-based practices. such information could highly contribute to improving the quality of services and upgrading the o&p facilities. acknowledgements the authors would like to thank the orthotics and prosthetics department (iran university of medical sciences) especially ms. fariba noori for her cooperation. the research team would also like to thank all the participants who generously shared their time and information. declaration of conflicting interests the authors declare that they have no competing interests. authors contribution ali baghbanbashi: conceived the idea, designed the analysis, collected the data, contributed to data analysis, contributed to the final manuscript behshid farahmand: conceived the idea and designed the analysis, supervised the project, contributed to data analysis, discussed the results and contributed to the final manuscript fatemeh azadinia: conceived the idea and designed the analysis, performed the data analysis, took the lead in writing the manuscript maryam jalali: conceived the idea and designed the analysis, discussed the results, provided critical feedback and contributed to the final manuscript sources of support the authors would like to thank the iran university of medical sciences for their official support of this study. ethical approval the present study is descriptive-analytical research whose protocol was approved by the ethics committee at iran university of medical sciences (iumc). https://doi.org/10.33137/cpoj.v5i1.37981 6 baghbanbashi a, farahmand b, azadinia f, jalali m. evaluation of user’s satisfaction with orthotic and prosthetic devices and services in orthotics and prosthetics center of iran university of medical sciences. canadian prosthetics & orthotics journal. 2022; 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[cited 2022 july 12]. available from: https://www.sralab.org/sites/default/files/201703/opus%20scoring%20guide.pdf 27.shahabi s, pardhan s, shabaninejad h, teymourlouy aa, tabrizi r, lankarani kb. toward good governance for the prosthetics and orthotics sector in iran: evidence from a qualitative study. prosthet orthot int. 2022;10-97. doi: 10.1097/pxr. 0000000000000102 28.alsancak se. splint satisfaction in the treatment of traumatic radial nerve injuries. prosthet orthot int. 2003;27(2):139-45. doi: 10.1080/03093640308726670 29.routhier f, vincent c, morissette mj, desaulniers l. clinical results of an investigation of paediatric upper limb myoelectric prosthesis fitting at the quebec rehabilitation institute. prosthet orthot int. 2001;25(2):119-31. doi: 10.1080/03093640108726585 https://doi.org/10.33137/cpoj.v5i1.37981 https://apps.who.int/iris/handle/10665/259209 https://media.behzisti.ir/d/2021/10/26/0/137702.pdf http://rcs.ir/news https://apps.who.int/iris/handle/10665/42682 https://www.sralab.org/sites/default/files/2017-03/opus%20scoring%20guide.pdf https://www.sralab.org/sites/default/files/2017-03/opus%20scoring%20guide.pdf all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 research article gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1.36847 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.36847 1 gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1.36847 research article effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance gholizadeh h1 , lemaire e.d1,2, nantel j3* 1 centre for rehabilitation research and development, ottawa hospital research institute, ottawa, canada. 2 department of medicine, faculty of medicine, university of ottawa, ottawa, canada. 3 school of human kinetics, faculty of health sciences, university of ottawa, ottawa, canada. introduction the vertical distance between the swinging foot’s toe region and the ground is defined as minimum swing toe clearance (mstc) and is a critical gait parameter since it is linked to tripping risk.1,2 mstc in able-bodied individual during level walking is approximately 13 mm, and is sensitive to swing leg ankle, knee, and hip angles.1,3,4 people with transtibial amputation have higher risk of tripping and falling than ablebodied individuals, which could be due to prosthetic component malfunction, or poor proprioception. literature showed any failure in prosthetic suspension system or restricted ankle dorsiflexion may decrease toe clearance in lower limb amputees.5-7 pistoning between the residual limb and prosthetic socket5,8 during swing can affect prosthetic length, which could cause insufficient mstc.5-7 choosing an appropriate prosthetic suspension system to connect the residual limb to the socket is a vital step in the rehabilitation process, leading to improved fit inside the socket and decreased pistoning.9-10 elevated vacuum suspension systems could decrease the pistoning between the residual limb and socket9-12 compared to other prosthetic suspension systems, and therefore improve mstc. in our previous research, we assessed the effect of össur’s unity figure 1 elevated vacuum suspension system (https://assets.ossur.com/library/33281/unity) on gait open access volume 5, issue 1, article no.1. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: the risk of tripping in people with amputation is greater than that of able-bodied individuals due to reduced toe clearance during the swing phase. appropriate prosthetic suspension may increase toe clearance by providing more secured attachment between the residual limb and prosthetic socket. research is lacking on the unity suspension system's effect on swing toe clearance. methods: twelve people with transtibial amputation were fitted with the unity suspension system. after one month accommodation period, the person walked with active (on) or inactive vacuum (off) in a caren-extended virtual reality system, across multiple simulated real-world scenarios. prosthetics minimum swing toe clearance, and kinematic data, while the vacuum was on or off, were compared with the intact side and a group of 12 able-bodied individuals. results: minimum swing toe clearance (mstc) and knee flexion angle were larger on the prosthetic side (active and inactive vacuum) compared to both the intact side and the control group. however, hip flexion angle on the prosthetic side was approximately 17% smaller than the control group. unlike the control group, mstc with active and inactive vacuum suspension was not significantly different between level walking and other walking conditions. finally, among all walking conditions, the lowest swing toe clearance for both control and the amputee groups was recorded when the limb was at the top of a side-slope. conclusion: an effective suspension system could improve toe clearance; however, significant differences were not found between active and inactive vacuum conditions. the likelihood of inappropriate foot contact on side-slope ground might be greater than other walking conditions for both able-bodied and amputee groups, possibly leading to stumbling or falling. article info received: june 21, 2021 accepted: october 6, 2021 published: october 23, 2021 citation gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1. 36847 keywords prosthesis, rehabilitation, lower limb amputation, gait, toe clearance, transtibial prosthesis, mobility, prosthetic suspension, amputation * corresponding author julie nantel, phd school of human kinetics, faculty of health sciences, university of ottawa, ottawa, canada, k1n 6n5 email: jnantel@uottawa.ca orcid id: https://orcid.org/0000-0001-7253-9222 https://doi.org/10.33137/cpoj.v5i1.36847 https://assets.ossur.com/library/33281/unity https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i1.36847 https://doi.org/10.33137/cpoj.v5i1.36847 mailto:jnantel@uottawa.ca https://orcid.org/0000-0001-7253-9222 2 gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1.36847 issn: 2561-987x effects of prosthetic suspension system on swing toe clearance gholizadeh et al., 2022 cpoj parameters while the vacuum was active or inactive.13-15 we found significant differences between vacuum conditions for some gait parameters, but differences were small and may not be clinically relevant. however, step length symmetry between intact and prosthetic limbs improved with active elevated vacuum. figure 1: unity suspension system. the effects of össur’s unity suspension system on mstc when walking on community-relevant surfaces with continuous perturbations have not yet been studied and this paper addresses that cap. walking over non-level surfaces is more challenging than level walking, especially for people with transtibial amputation as they must continually adapt their movement patterns due to the increased biomechanical demands of continuously variable terrain.13,14,16 in addition, more challenging walking conditions, may require higher cognitive demand compared to level walking, which could lead to a more cautious gait pattern.17,18 therefore, the purpose of this study was to evaluate the effects of the system on mstc and kinematics at the hip, knee and ankle during gait across multiple simulated real-world walking scenarios by comparing the prosthetic side, with active and inactive vacuum suspension, to the intact limb. moreover, mstc and gait kinematics were compared between the amputee group and 12 able-bodied individuals for the first time in this study. we hypothesized that statistically significant differences will occur between able-bodied participants and the transtibial amputation group regarding mstc and ankle, knee and hip angles, across all walking conditions. moreover, unity users are hypothesized to have larger mstc on the intact side compared to the prosthetic side with active (on) or inactive vacuum (off). we also hypothesized that positive correlations would occur between mstc and ankle, knee, and hip angles during different walking conditions. this study can enhance clinicians' and prescribers' understanding of unity suspension system’s effects on mstc, which can help provide safe mobility for people with limb loss. methodology a convenience sample of 12 active people with unilateral transtibial amputation (11 males, 1 female) who used their prosthesis daily was recruited from the ottawa hospital rehabilitation centre. the participant’s mean height was 178.3 (sd=6.4) cm, weight was 90.6 (sd=16.4) kg, age was 57.2 (sd=15.3) years, and time since amputation was 13.1 (sd=20.0) years. data from a group of 12 able-bodied individuals (11 males, 1 female) from our databases were compared with the amputee group. control group mean height was 176.6 (sd=7.8) cm; weight was 81.4 (sd=11.0) kg; and age was 38.3 (sd=10.6) years. the ottawa hospital research ethics board approved the study protocol and all participants provided written informed consent. 2.1. data collection a new prosthesis with an iceross seal-in v liner and a proflex xc foot with unity pump was fabricated for each participant and after one month acclimation period, threedimensional motion analysis was collected in the caren extended virtual reality lab. participants walked at their own comfortable self-selected walking speed and completed walking trials with vacuum inactive (off) or active (on). the order of active and inactive vacuum was randomized and blinded for the participants. the average self-selected walking speed were 1.07 (sd: 0.23) and 1.03 (sd: 0.20) m/s for inactive and active vacuum respectively. this methodology has been described in detail in our previous publications.13-15 the average self-selected walking speed for the control group was slightly higher (mean: 1.29 (sd: 0.06) m/s). each walking trial was 340 m that included: level walking; down slope (7° decline); up slope (7° incline); right and left slopes (5° slope); medial-lateral translations (platform oscillates in the medial-lateral direction); hilly (platform oscillates in the sagittal plane); and rocky conditions. right and left slopes were separated into top cross-slope (ts) and bottom cross-slope (bs). during right slope, the right limb was at the bottom of the slope and the left limb was at the top. during left slope, the right limb was at the top and the left limb was at the bottom of the slope. 2.2. data analysis vicon nexus software version 2.3 (vicon, oxford uk) and visual3d software version 6 (c-motion, germantown, md) were used for gait analysis. helen hayes markers set was used in this study. heel (posterior and lateral side), 5th metatarsal head, and 2nd metatarsal head makers were secured to the shoes. the 5th metatarsal marker was used to track the toe position (toe marker). minimum toe marker position during swing phase of gait was determined and subtracted from the baseline (toe marker position during the mid-stance) to calculate mstc. also, hip, knee, and ankle https://doi.org/10.33137/cpoj.v5i1.36847 3 gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1.36847 issn: 2561-987x effects of prosthetic suspension system on swing toe clearance gholizadeh et al., 2022 cpoj angles were determined at the point of mstc. data were analyzed using microsoft excel (version 2010) and spss (version 23.0). shaprio-wilk tests were used to evaluate data normality and p<0.05 was considered statistically significant. one-way repeated measures anovas were used to find the effect of walking condition on each variable. a one-way anova with a bonferroni adjustment for multiple comparisons was used to compare between prosthetic (on, off) and intact side and data from 12 able-bodied individuals (control group). pearson's correlation coefficients (pearson’s r) were used to determine the strength of linear relationship between mstc and the joint angle at the ankle, knee and hip. results mean and standard deviation of mstc and hip, knee, and ankle angles at the time of mstc are presented in table 1. descriptive statistics showed that mstc, knee, and hip angle were mostly greater on the prosthetic side (on and off) than on the intact side (table 1). mstc and knee angle were greater on the prosthetic side (vacuum on and off) than able-bodied individuals; however, prosthetic hip angle was smaller. maximum mstc and knee angle occurred during down slope for both vacuum conditions. however, in the able-bodied group, maximum mstc occurred during rocky and knee angle occurred during up slope walking. maximum hip angle occurred during up slope walking for both amputee and able-bodied groups. lowest mstc occurred when the limb was at the top of the crossslope, for all participants. much larger differences were found between knee and hip angles for amputees than ablebodied individuals. for example, the largest differences between knee and hip angles during down slope walking were approximately 22 degrees for amputees (prosthetic side-vacuum on) compared to 11 degrees for able-bodied participants. one-way repeated measures anova showed no significant mstc differences between level walking and other walking conditions in the transtibial amputation group (both prosthetic and intact sides) (table 2, figure 2). however, in the able-bodied group, mstc during level walking was significantly smaller than other walking conditions except top cross-slope (table 2). hip angle was significantly different (p<0.001) between level walking and up slope walking, for prosthetic and intact sides (vacuum on and off). however, able-bodied group hip angle during level walking was significantly different than other conditions, except bottom cross-slope. one-way anova results (table 3) showed significant differences (p<0.05) between the control group and unity table 1: mean and standard deviation (in brackets) of minimum swing toe clearance (mstc, cm) and ankle, knee, and hip angles (degrees) at the time of mstc. walking conditions are lw: level; ds: down slope; us: up slope; hl: hilly; ts: top cross-slope; bs: bottom crossslope; ml: medio-lateral; ro: rocky. walking conditions intact limb prosthetic limb mstc ankle knee hip mstc ankle knee hip 1 2 t ra n s ti b ia l a m p u te e s v a c u u m o n lw 1.9 (0.8) 2.2 (2.5) 25.4 (5.5) 16.4 (7.2) 2.2 (0.9) 3.0 (1.6) 31.4 (4.0) 19.1 (6.9) ds 2.5 (0.8) 2.8 (2.6) 31.1 (5.9) 14.6 (8.3) 3.1 (0.5) 38.9 (6.6) 17.4 (7.8) us 2.1 (0.9) 7.0 (2.8) 34.5 (7.9) 29.5 (9.8) 2.3 (0.9) 35.6 (6.2) 32.9 (9.9) hl 1.8 (0.4) 1.9 (1.8) 26.4 (4.6) 17.9 (7.9) 2.6 (0.5) 32.0 (6.6) 20.3 (8.3) ts 1.2 (0.9) 4.2 (2.7) 29.4 (5.5) 20.4 (7.6) 1.6 (0.6) 33.3 (7.5) 22.1 (8.0) bs 2.4 (0.7) 0.6 (2.4) 24.0 (5.5) 15.0 (7.9) 2.8 (0.6) 30.0 (3.8) 17.8 (7.1) ml 1.8 (0.6) 2.2 (2.1) 26.1 (5.1) 17.7 (8.0) 2.2 (0.7) 30.9 (5.0) 20.0 (8.0) ro 2.1 (0.6) 1.7 (2.5) 27.5 (5.0) 18.5 (7.8) 2.7 (0.5) 32.1 (4.8) 20.9 (7.6) average (sd) 2.0 (0.4) 2.8 (2.0) 28.1 (3.4) 18.8 (4.7) 2.4 (0.5) 33.0 (2.9) 21.3 (4.9) v a c u u m o f f lw 2.1 (1.2) 2.8 (3.2) 25.7 (4.6) 17.3 (7.6) 2.4 (1.1) 3.0 (1.6) 31.7 (6.2) 19.6 (7.1) ds 2.7 (1.2) 3.2 (3.3) 30.8 (3.6) 15.2 (8.5) 3.2 (0.7) 38.0 (7.2) 17.5 (8.2) us 2.8 (1.3) 7.8 (2.7) 37.6 (6.7) 31.5 (7.9) 2.6 (1.1) 36.7 (7.0) 33.6 (8.5) hl 2.4 (1.4) 2.6 (3.7) 27.2 (5.5) 18.7 (8.8) 2.8 (1.4) 32.5 (6.3) 20.4 (8.2) ts 1.3 (0.5) 4.6 (3.0) 29.6 (5.6) 20.6 (7.5) 1.8 (0.4) 33.0 (6.5) 23.0 (7.5) bs 2.6 (0.6) 1.0 (2.8) 24.6 (4.6) 15.6 (7.1) 3.0 (0.8) 30.8 (6.0) 18.4 (7.0) ml 2.2 (1.3) 3.0 (3.1) 26.9 (5.5) 17.9 (7.9) 2.5 (1.1) 31.0 (6.0) 20.3 (7.7) ro 2.3 (0.6) 2.9 (3.0) 28.4 (5.5) 18.9 (7.7) 3.0 (0.5) 31.0 (3.8) 20.3 (8.1) average (sd) 2.3 (0.5) 3.5 (2.0) 28.9 (4.1) 19.5 (5.2) 2.7 (0.4) 33.1 (2.8) 21.6 (5.1) 1 2 a b le -b o d ie d (a v e ra g e o f b o th l e g s ) lw 1.6 (0.4) 0.3 (2.0) 25.4 (5.1) 23.1 (5.0) ds 2.4 (0.6) 1.4 (2.7) 29.3 (6.3) 18.7 (6.3) us 2.6 (0.8) 7.3 (3.4) 38.8 (4.5) 38.7 (5.9) hl 2.6 (0.5) 1.1 (2.4) 28.6 (5.4) 25.7 (5.8) ts 1.4 (0.5) 1.6 (1.9) 27.5 (5.7) 26.2 (5.5) bs 2.5 (0.6) -1.4 (2.2) 24.3 (4.3) 22.7 (4.9) ml 2.2 (0.6) 0.8 (2.3) 27.0 (4.4) 25.1 (5.2) ro 2.9 (0.9) 1.7 (3.0) 28.7 (5.3) 26.6 (6.0) average (sd) 2.3 (0.5) 1.6 (2.5) 28.7 (4.4) 25.9 (5.8) https://doi.org/10.33137/cpoj.v5i1.36847 4 gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1.36847 issn: 2561-987x effects of prosthetic suspension system on swing toe clearance gholizadeh et al., 2022 cpoj users (vacuum on and off) for mstc and knee angle during down slope walking (table 3). knee angle was significantly different between groups for level and bottom cross-slope conditions. during level walking, mstc was greater (p=0.041) for unity users (vacuum off) than the control group. pearson correlation coefficients were low between mstc and ankle, knee, and hip in able-bodied individuals during different walking conditions (table 4). correlations were also low between mstc and hip angle in people with transtibial amputation, on both prosthetic and intact sides (vacuum on and off). low correlations were found between mstc and knee angle on the prosthetic side when vacuum was on. high correlations were found between mstc and knee angle during hilly and medio-lateral walking when the vacuum was off (prosthetic side). a strong correlation was found between mstc and ankle angle during level walking and down-slope walking on the intact side when vacuum was on. moderate and strong correlations were also found between mstc and ankle angle during different walking conditions on the intact side (vacuum off) (table 4). discussion in this research, we evaluated the effects of the unity elevated vacuum suspension system on mstc during gait. all people in this study had acceptable mstc, which allowed their feet to clear the ground safely when walking across multiple simulated real-world walking scenarios. overall, mstc and knee angles were larger and hip angles were smaller on the prosthetic side (vacuum on and off) than the able-bodied individuals. different from the control group, no significant mstc differences were found between level walking and other walking conditions, in the amputee group for both prosthetic and intact sides (vacuum on and off). unexpectedly, we found no statistically significant differences between vacuum on and off conditions for mstc, knee, and hip angles. for the able-bodied group, mstc was approximately 1.6 cm during level walking, which was similar to the previously reported results.2,3,19 similar to findings by sinitski et al.,20 in amputees, mstc was greater on the prosthetic side (vacuum on and off) than the intact side and greater than results from able-bodied individuals for most of walking conditions. this outcome differed from the previous literature where the absence of a controllable prosthetic ankle joint caused insufficient mstc, thereby potentially increasing tripping risk.6,21,22 furthermore, gates et al., (2012) found that mstc in people with transtibial amputation was 1.3 times greater on the intact side than the prosthetic side.17 johnson et al., (2014) suggested that using a prosthetic foot with a hydraulic ankle joint could provide adequate toe clearance (2.2 cm) during level walking.6 the current study showed that using unity suspension system could also provide similar mstc to allow the foot to clear the ground safely during level walking. t a b le 2 : m e a n d if fe re n c e ( d e g re e s ) a n d p -v a lu e b e tw e e n l e v e l w a lk in g ( b a s e lin e ) a n d o th e r w a lk in g c o n d it io n s . b o ld s ig n if ie s a s ig n if ic a n t d if fe re n c e . l w : l e v e l; d s : d o w n s lo p e ; u s : u p s lo p e ; h l : h ill y ; t s : t o p c ro s s -s lo p e ; b s : b o tt o m c ro s s -s lo p e ; m l : m e d io -l a te ra l; r o : r o c k y in t a c t p r o s t h e t ic m s t c a n k le k n e e h ip m s t c a n k le k n e e h ip m e a n d if fe re n c e p v a lu e s m e a n d if fe re n c e p v a lu e s m e a n d if fe re n c e p v a lu e s m e a n d if fe re n c e p v a lu e s m e a n d if fe re n c e p v a lu e s m e a n d if fe re n c e p v a lu e s m e a n d if fe re n c e p v a lu e s 12 transtibial amputees vacuum on d s 0 .6 1 1 .0 0 0 0 .5 9 1 .0 0 0 5 .7 2 0 .0 7 5 1 .8 4 1 .0 0 0 0 .9 3 0 .0 6 3 7 .4 6 0 .0 0 1 1 .7 6 1 .0 0 0 u s 0 .2 0 1 .0 0 0 4 .8 7 0 .0 0 1 9 .1 0 0 .0 0 7 1 3 .0 8 0 .0 0 0 0 .1 1 1 .0 0 0 4 .2 6 0 .1 5 9 1 3 .7 7 0 .0 0 0 h l 0 .1 1 1 .0 0 0 0 .3 0 1 .0 0 0 0 .9 9 1 .0 0 0 1 .4 5 0 .6 7 0 0 .4 5 1 .0 0 0 0 .6 5 1 .0 0 0 1 .1 9 1 .0 0 0 t s 0 .6 9 1 .0 0 0 1 .9 9 0 .0 1 2 3 .9 6 0 .2 2 4 4 .0 1 0 .0 0 0 0 .5 3 1 .0 0 0 1 .8 6 1 .0 0 0 2 .9 5 0 .0 8 7 b s 0 .4 8 1 .0 0 0 1 .5 8 0 .3 1 3 1 .3 4 1 .0 0 0 1 .4 4 1 .0 0 0 0 .6 5 1 .0 0 0 1 .3 6 1 .0 0 0 1 .3 3 1 .0 0 0 m l 0 .1 3 1 .0 0 0 0 .0 4 1 .0 0 0 0 .7 6 1 .0 0 0 1 .3 1 0 .3 2 5 0 .0 9 1 .0 0 0 0 .5 2 1 .0 0 0 0 .8 8 1 .0 0 0 r o 0 .1 8 1 .0 0 0 0 .4 8 1 .0 0 0 2 .1 5 1 .0 0 0 2 .1 1 0 .1 0 6 0 .5 8 1 .0 0 0 0 .7 6 1 .0 0 0 1 .7 6 0 .5 9 0 vacuum off d s 0 .6 4 1 .0 0 0 0 .3 7 1 .0 0 0 5 .0 9 0 .0 2 1 2 .0 9 1 .0 0 0 0 .8 6 0 .1 1 0 6 .2 9 0 .0 1 4 2 .1 0 1 .0 0 0 u s 0 .6 8 0 .1 7 7 4 .9 9 0 .0 0 0 1 1 .8 6 0 .0 0 0 1 4 .2 3 0 .0 0 0 0 .2 3 1 .0 0 0 5 .0 4 0 .0 1 5 1 3 .9 8 0 .0 0 0 h l 0 .3 4 1 .0 0 0 0 .1 8 1 .0 0 0 1 .5 3 1 .0 0 0 1 .4 2 1 .0 0 0 0 .4 9 0 .1 1 7 0 .8 4 1 .0 0 0 0 .7 5 1 .0 0 0 t s 0 .7 8 0 .2 8 5 1 .7 6 0 .0 0 9 3 .8 8 0 .0 3 2 3 .2 9 0 .0 0 2 0 .5 5 1 .0 0 0 1 .3 1 1 .0 0 0 3 .3 6 0 .0 0 3 b s 0 .5 1 1 .0 0 0 1 .8 4 0 .1 4 4 1 .1 1 1 .0 0 0 1 .6 3 1 .0 0 0 0 .6 1 0 .9 9 5 0 .8 5 1 .0 0 0 1 .1 6 1 .0 0 0 m l 0 .1 3 1 .0 0 0 0 .1 3 1 .0 0 0 1 .1 7 1 .0 0 0 0 .6 2 1 .0 0 0 0 .1 1 1 .0 0 0 0 .6 9 1 .0 0 0 0 .6 6 1 .0 0 0 r o 0 .2 4 1 .0 0 0 0 .1 1 1 .0 0 0 2 .7 0 0 .5 7 9 1 .6 8 1 .0 0 0 0 .6 0 1 .0 0 0 0 .6 9 1 .0 0 0 0 .6 8 1 .0 0 0 12 able-bodied (average of both legs) d s 0 .7 4 0 .0 0 3 1 .1 0 1 .0 0 0 3 .8 7 0 .2 2 2 4 .4 4 0 .0 0 8 u s 0 .9 3 0 .0 1 0 7 .0 8 0 .0 0 0 1 3 .3 6 0 .0 0 0 1 5 .5 6 0 .0 0 0 h l 0 .9 2 0 .0 0 1 0 .8 8 1 .0 0 0 3 .2 1 0 .2 2 6 2 .5 6 0 .0 4 3 t s 0 .2 5 0 .2 8 1 .3 8 0 .0 1 2 .1 2 0 .1 9 0 3 .0 8 0 .0 0 1 b s 0 .8 8 0 .0 0 0 1 .6 6 0 .0 0 0 1 .0 8 0 .6 7 0 0 .4 4 0 .9 5 6 m l 0 .5 5 0 .0 3 7 0 .5 6 1 .0 0 0 1 .6 2 1 .0 0 0 2 .0 0 0 .0 2 1 r o 1 .2 1 0 .0 0 3 1 .4 9 0 .8 8 2 3 .3 3 0 .2 4 5 3 .5 6 0 .0 2 3 https://doi.org/10.33137/cpoj.v5i1.36847 5 gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1.36847 issn: 2561-987x effects of prosthetic suspension system on swing toe clearance gholizadeh et al., 2022 cpoj table 3: p values for comparisons between amputee group (prosthetic side) and able-bodied group; a= able-bodied; b= unity on; c= unity off. bold signifies a significant difference. walking conditions are lw: level; ds: down slope; us: up slope; hl: hilly; ts: top cross-slope; bs: bottom cross-slope; ml: medio-lateral; ro: rocky. (a,b) (a,c) (b,c) lw mstc 0.316 0.041 1.000 knee angle 0.024 0.017 1.000 hip angle 0.413 0.571 1.000 ds mstc 0.028 0.007 1.000 knee angle 0.004 0.010 1.000 hip angle 1.000 1.000 1.000 us mstc 1.000 1.000 1.000 knee angle 0.630 1.000 1.000 hip angle 0.296 0.433 1.000 hl mstc 1.000 1.000 1.000 knee angle 0.532 0.381 1.000 hip angle 0.274 0.281 1.000 ts mstc 0.811 0.148 1.000 knee angle 0.126 0.156 0.515 hip angle 0.498 0.827 1.000 bs mstc 0.936 0.312 1.000 knee angle 0.019 0.007 1.000 hip angle 0.220 0.355 1.000 ml mstc 1.000 1.000 1.000 knee angle 0.226 0.202 1.000 hip angle 0.265 0.316 1.000 ro mstc 1.000 1.000 1.000 knee angle 0.252 0.746 1.000 hip angle 0.186 0.125 1.000 figure 2: minimum swing toe clearance in different walking conditions. a comparison between the unity (vacuum on and off) and able-bodied group. this might be due to improved proprioception and socket fit (less pistoning inside the socket) with the iceross seal-in v liner.15 literature shows that people adopt a more cautious gait pattern while walking on more challenging walking conditions.13,14,16 moreover, merryweather et al., (2011) found that mstc increased significantly when walking on irregular surfaces compared to level walking.23 similarly, we found that able-bodied participants adapted their mstc to different walking conditions, either by increasing ankle or hip angle. however, there were no significant differences in knee angle between level walking and other conditions, except during upslope walking where knee angle increased approximately 14 degrees (38.8 (sd = 4.5) versus 25.4 (sd = 5.1)) at the point of mstc. this was expected since incline walking requires the foot to be raised and then contact the ground above the stance limb. people with transtibial amputation also adapted their gait on more challenging walking conditions; however, there were no significant differences in mstc between level walking and other conditions. the lowest mstc for amputee and control groups was when the limb was at the top of the cross-slope; therefore, the probability of a stumble scenario on top crossslopes might be greater than other walking conditions. in the current study, platform tilts to the right or left with a 5° slope; thus, different angles of cross-slope should be tested to determine the risk of tripping in able-bodied and people with transtibial amputation. maximum mstc and knee angle occurred during down slope for the vacuum on and off. similarly, the literature showed that knee flexion increased during down slope walking since the prosthetic foot (heel) is not able to deform effectively to reach foot-flat.24 amputees in the current study typically had larger mstc than the able-bodied individuals, therefore mstc was sufficient to clear the ground and possibly reduce tripping probability. based on the literature, knee extensors and flexors strength in the amputated side is reduced in comparison with the intact side.25,26 moreover, loss of muscles, tendons, and active ankle dorsiflexion/plantarflexion in the amputated side may compromise function and proprioception.27 therefore, we had expected to have larger mstc on the intact side compared to the prosthetic side with active (on) or inactive vacuum (off). however, we found larger mstc in the prosthetic side than the intact side and the able-bodied individuals. this larger mstc in prosthetic side could be an anticipatory strategy used by people with amputation. previous research also suggested that, compared to young individuals, older adults actively increase foot clearance as an anticipatory strategy to reduce the risk of contact between the toes and the ground which could cause tripping/falling.28,29 sensinger et al., (2012) also indicated that prosthesis users use different strategies such as vaulting and hip hiking to compensate for inadequate toe clearance.30 larger mstc in people with transtibial amputation in the current study might also be due to these protective strategies for clearing the ground safely. appropriate swing toe clearance could be achieved by reducing effective lower limb length via synchronized ankle, knee, and hip flexion.20 one study suggested that increasing hip flexion could increase mstc.6 the current study showed that able-bodied individuals had larger hip angle than the amputee group; nevertheless, mstc was smaller in the able-bodied group. moosabhoy and gard (2006) found that knee and hip have fewer effects on mstc than ankle.31 similarly, we found no correlation between mstc and hip angle for amputee and able-bodied groups, whereas higher correlations were found between ankle angle and mstc in the amputee’s intact side. 0 0.5 1 1.5 2 2.5 3 3.5 lw ds us hl ts bs ml ro m s t c ( c m ) walking conditions able-bodied vacuum on vacuum off https://doi.org/10.33137/cpoj.v5i1.36847 6 gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1.36847 issn: 2561-987x effects of prosthetic suspension system on swing toe clearance gholizadeh et al., 2022 cpoj prosthetic elevated vacuum suspension system could improve socket fit and proprioception, which could enhance gait symmetry in people with transtibial amputation.12,32 similarly, our previous study showed better proprioception and greater comfort for unity users with vacuum on compared to vacuum off.15 the current study showed non-significant increase of the knee and hip angles in most walking conditions when the vacuum was off compared to vacuum on. increased knee and hip angles could be an anticipatory strategy used by amputees, possibly due to less proprioception with vacuum off, to ensure enough toe clearance. this should be further investigated with a larger number of participants. a high functioning transtibial amputees group with k3 and k4 activity level33 participated in the current study. future research should examine effects of the unity suspension system on mstc for lower activity level (k1-k2) to assist in clinical decision-making. one month of accommodation was provided for the unity suspension system, but no accommodation period was provided for the vacuum off condition. using the prosthesis with vacuum off for hours or longer may affect limb volume and socket comfort, where discomfort and inappropriate socket function could affect the gait. therefore, we only evaluated the immediate effect of vacuum off during testing by detaching the distal unity tube and removing negative pressure inside the socket. conclusion effective prosthetic suspension system could improve mstc and might decrease the risk of tripping and falling. the results of this study showed that active people with transtibial amputation could have appropriate mstc during gait, when using the unity suspension system. this prosthetic configuration could reduce anticipatory strategies to compensate for the absence of a controllable prosthetic ankle joint. acknowledgements the authors would like to thank knut lechler for providing clinical and technical advice and support. emily sinitski, and courtney bridgewater are thanked for assistance with clinical testing. declaration of conflicting interests the authors declare that there is no conflict of interest. author contribution • hossein gholizadeh: study design, data collection, data analyses and writing of the manuscript. • edward d. lemaire: study design, supervision, review and editing of the manuscript. table 4: correlation between mstc, knee, and hip angles. correlations greater than 0.5 (moderate and strong correlation) are in bold. confidence intervals are presented in parentheses. lw: level; ds: down slope; us: up slope; hl: hilly; ts: top cross-slope; bs: bottom cross-slope; ml: medio-lateral; ro: rocky. intact prosthetic mstc-ankle mstc-knee mstc-hip mstc-knee mstc-hip 1 2 t ra n s ti b ia l a m p u te e s u n it y o n lw 0.65* (0.121, 0.891) 0.15 (-0.464, 0.667) 0.33 (-0.301, 0.760) -0.01 (-0.581, 0.567) 0.27 (-0.360, 0.731) ds 0.69* (0.192, 0.905) 0.51 (-0.090, 0.838) 0.44 (-0.179, 0.809) -0.15 (-0.667, 0.464) -0.12 (-0.649, 0.487) us 0.10 (-0.503, 0.637) 0.54 (-0.049, 0.850) 0.47 (-0.142, 0.822) -0.23 (-0.710, 0.396) 0.07 (-0.525, 0.619) hl 0.48 (-0.130, 0.826) -0.26 (-0.726, 0.369) 0.07 (-0.525, 0.619) -0.28 (-0.736, 0.350) 0.25 (-0.378, 0.721) ts -0.31 (-0.750, 0.321) 0.09 (-0.510, 0.631) -0.30 (-0.746, 0.331) 0.12 (-0.487, 0.649) 0.39 (-0.237, 0.788) bs 0.50 (-0.104, 0.834) 0.19 (-0.431, 0.689) 0.27 (-0.360, 0.731) -0.22 (-0.705, 0.405) 0.05 (-0.539, 0.607) ml 0.32 (-0.311, 0.755) -0.10 (-0.637, 0.503) 0.17 (-0.448, 0.678) 0.25 (-0.378, 0.721) 0.16 (-0.456, 0.672) ro 0.42 (-0.203, 0.801) 0.48 (-0.130, 0.826) 0.19 (-0.431, 0.689) -0.14 (-0.661, 0.472) 0.10 (-0.503, 0.637) u n it y o f f lw 0.76* (0.330, 0.929) 0.35 (-0.280, 0.769) 0.34 (-0.291, 0.765) 0.52 (-0.077, 0.842) 0.43 (-0.191, 0.805) ds 0.53 (-0.063, 0.846) 0.39 (-0.237, 0.788) 0.48 (-0.130, 0.826) 0.28 (-0.350, 0.736) 0.34 (-0.291, 0.765) us 0.74* (-0.063, 0.846) 0.58* (0.009, 0.866) -0.02 (-0.587, 0.560) 0.47 (-0.142, 0.822) -0.05 (-0.607, 0.539) hl 0.78* (0.373, 0.935) 0.57* (-0.006, 0.862) 0.36 (-0.270, 0.774) 0.73* (0.269, 0.919) 0.44 (-0.179, 0.809) ts 0.54 (-0.049, 0.850) 0.38 (-0.248, 0.783) 0.14 (-0.472, 0.661) 0.37 (-0.259, 0.779) 0.09 (-0.510, 0.631) bs 0.69* (0.192, 0.905) -0.41 (-0.796, 0.214) 0.12 (-0.487, 0.649) 0.26 (-0.369, 0.726) 0.23 (-0.396, 0.710) ml 0.83* (0.489, 0.951) 0.50 (-0.104, 0.834) 0.36 (-0.270, 0.774) 0.62* (0.072, 0.881) 0.25 (-0.378, 0.721) ro 0.56 (-0.020, 0.858) 0.22 (-0.405, 0.705) 0.11 (-0.495, 0.643) -0.39 (-0.788, 0.237) 0.16 (-0.456, 0.672) 1 2 a b le -b o d ie d (a v e ra g e o f b o th le g s ) lw 0.49 (-0.117, 0.830) 0.24 (-0.387, 0.715) 0.15 (-0.464, 0.667) ds 0.35 (-0.280, 0.769) 0.09 (-0.510, 0.631) -0.12 (-0.649, 0.487) us 0.45 (-0.167, 0.814) 0.30 (-0.331, 0.746) 0.09 (-0.510, 0.631) hl 0.09 (-0.510, 0.631) -0.15 (-0.667, 0.464) -0.03 (-0.594, 0.553) ts 0.35 (-0.280, 0.769) 0.10 (-0.503, 0.637) -0.01 (-0.581, 0.567) bs 0.40 (-0.226, 0.792) -0.27 (-0.731, 0.360) -0.13 (-0.655, 0.480) ml 0.42 (-0.203, 0.801) 0.33 (-0.301, 0.760) -0.05 (-0.607, 0.539) ro 0.43 (-0.191, 0.805) 0.17 (-0.448, 0.678) 0.35 (-0.280, 0.769) https://doi.org/10.33137/cpoj.v5i1.36847 7 gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1.36847 issn: 2561-987x effects of prosthetic suspension system on swing toe clearance gholizadeh et al., 2022 cpoj • julie nantel: study design, supervision, review and editing of the manuscript. sources of support this study was financially supported by mitacs and össur. all prosthetics components were provided by össur. ethical approval the ottawa hospital research ethics board approved the study protocol and all participants provided written informed consent. references 1.winter da. biomechanics and motor control of human gait: normal, elderly and pathological. 1991. 2.mills pm, barrett rs. swing phase mechanics of healthy young and elderly men. hum mov sci. 2001;20(4–5):427–46. doi: 10.1016/s0167-9457(01)00061-6 3.winter da. foot trajectory in human gait: a precise and multifactorial motor control task. phys ther. 1992;72(1):45–53. doi: 10.1093/ptj/72.1.45 4.winter da, patla ae, frank js, walt se. biomechanical walking pattern changes in the fit and healthy elderly. phys ther. 1990;70(6):340–7. doi: 10.1093/ptj/70.6.340 5.eshraghi a, osman naa, gholizadeh h, karimi m, ali s. pistoning assessment in lower limb prosthetic sockets. prosthet orthot int. 2012;36(1):15–24. doi: 10.1177/0309364611431625 6.johnson l, de asha ar, munjal r, kulkarni j, buckley jg. toe clearance when walking in people with unilateral transtibial amputation: effects of passive hydraulic ankle. j rehabil res dev. 2014;51(3):429-37. doi: 10.1682/jrrd.2013.05.0126 7.lechler k, kristjansson k. the importance of additional mid swing toe clearance for amputees. can prosthet orthot j. 2018;1(2). doi:10.33137/cpoj.v1i2.30813 8.gholizadeh h, osman na, kamyab m, eshraghi a, abas ww, azam mn. transtibial prosthetic socket pistoning: static evaluation of seal-in® x5 and dermo® liner using motion analysis system. clin biomech. 2012;27(1):34–9. doi: 10.1016/j.clinbiomech.2011. 07.004 9.baars ect, geertzen jhb. literature review of the possible advantages of silicon liner socket use in trans-tibial prostheses. prosthet orthot int. 2005;29(1):27–37. doi: 10.1080/ 17461550500069612 10.gholizadeh h, lemaire ed, eshraghi a. the evidence-base for elevated vacuum in lower limb prosthetics: literature review and professional feedback. clin biomech. 2016;37:108–16. doi: 10.1016/j.clinbiomech.2016.06.005 11.xu h, greenland k, bloswick d, zhao j, merryweather a. vacuum level effects on gait characteristics for unilateral transtibial amputees with elevated vacuum suspension. clin biomech. 2017;43:95–101. doi: 10.1016/j.clinbiomech.2017.02.008 12.board wj, street gm, caspers c. a comparison of trans-tibial amputee suction and vacuum socket conditions. prosthet orthot int. 2001;25(3):202–9. doi: 10.1080/03093640108726603 13.thibault g, gholizadeh h, sinitski e, baddour n, lemaire ed. effects of the unity vacuum suspension system on transtibial gait for simulated non-level surfaces. plos one. 2018;13(6):e0199181. doi: 10.1371/journal.pone.0199181 14.gholizadeh h, lemaire ed, sinitski eh. transtibial amputee gait during slope walking with the unity suspension system. gait posture. 2018;65:205–12. doi: 10.1016/j.gaitpost.2018.07.059 15.gholizadeh h, lemaire ed, sinitski eh, nielen d, lebel p. transtibial amputee gait with the unity suspension system. disabil rehabil assist technol. 2020;15(3):350-356. doi: 10.1080/ 17483107.2019.1579000 16.sinitski eh, lemaire ed, baddour n, besemann m, dudek nl, hebert js. fixed and self-paced treadmill walking for able-bodied and transtibial amputees in a multi-terrain virtual environment. gait posture. 2015;41(2):568–73. doi: 10.1016/j.gaitpost.2014.12.016 17.gates dh, dingwell jb, scott sj, sinitski eh, wilken jm. gait characteristics of individuals with transtibial amputations walking on a destabilizing rock surface. gait posture. 2012;36(1):33–9. doi: 10.1016/j.gaitpost.2011.12.019 18.young pmm, wilken jm, dingwell jb. dynamic margins of stability during human walking in destabilizing environments. j biomech. 2012;45(6):1053–9. doi: 10.1016/j.jbiomech.2011.12. 027 19.begg r, best r, dell’oro l, taylor s. minimum foot clearance during walking: strategies for the minimisation of trip-related falls. gait posture. 2007;25(2):191–8. doi: 10.1016/j.gaitpost.2006. 03.008 20.sinitski eh, lemaire ed, baddour n, besemann m, dudek n, hebert js. maintaining stable transtibial amputee gait on level and simulated uneven conditions in a virtual environment. disabil rehabil assist technol. 2021;16(1):40–8. doi: 10.1080/ 17483107.2019.1629186 21.rosenblatt nj, bauer a, rotter d, grabiner md. active dorsiflexing prostheses may reduce trip-related fall risk in people with transtibial amputation. j rehabil res dev. 2014;51(8). doi: 10.1682/jrrd.2014.01.0031 22.miller wc, speechley m, deathe b. the prevalence and risk factors of falling and fear of falling among lower extremity amputees. arch phys med rehabil. 2001;82(8):1031–7. doi: 10.1053/apmr.2001.24295 23.merryweather a, yoo b, bloswick d. gait characteristics associated with trip-induced falls on level and sloped irregular surfaces. minerals. 2011;1(1):109–21. doi:10.3390/min1010109 24.fradet l, alimusaj m, braatz f, wolf si. biomechanical analysis of ramp ambulation of transtibial amputees with an adaptive ankle foot system. gait posture. 2010;32(2):191–8. doi: 10.1016/ j.gaitpost.2010.04.011 25.fontes ch da s, laett ct, gavilão uf, campos jc de, alexandre dj de a, cossich vr, et al. bodyweight distribution between limbs, muscle strength, and proprioception in traumatic transtibial amputees: a cross-sectional study. clinics. 2021;76. doi: 10.6061/clinics/2021/e2486 26.isakov e, burger h, gregorič m, marinček c. isokinetic and isometric strength of the thigh muscles in below-knee amputees. clin biomech. 1996;11(4):233–5. doi: 10.1016/0268-0033(95) 00078-x https://doi.org/10.33137/cpoj.v5i1.36847 8 gholizadeh h, lemaire e.d, nantel j. effects of unity prosthetic elevated vacuum suspension system on minimum swing toe clearance. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.1. https://doi.org/10.33137/cpoj.v5i1.36847 issn: 2561-987x effects of prosthetic suspension system on swing toe clearance gholizadeh et al., 2022 cpoj 27.smith dg, fergason jr. transtibial amputations. clin. orthop. relat. res. 1999;361:108-15. 28.mills pm, barrett rs, morrison s. toe clearance variability during walking in young and elderly men. gait posture. 2008;28(1):101–7. doi: 10.1016/j.gaitpost.2007.10.006 29.sparrow wa, begg rk, parker s. variability in the foot-ground clearance and step timing of young and older men during singletask and dual-task treadmill walking. gait posture. 2008;28(4):563– 7. doi: 10.1016/j.gaitpost.2008.03.013 30.sensinger jw, intawachirarat n, gard sa. contribution of prosthetic knee and ankle mechanisms to swing-phase foot clearance. ieee trans neural syst rehabil eng. 2012;21(1):74– 80. doi: 10.1109/tnsre.2012.2224885 31.moosabhoy ma, gard sa. methodology for determining the sensitivity of swing leg toe clearance and leg length to swing leg joint angles during gait. gait posture. 2006;24(4):493–501. doi: 10.1016/j.gaitpost.2005.12.004 32.ferreira aek, neves eb. a comparison of vacuum and kbm prosthetic fitting for unilateral transtibial amputees using the gait profile score. gait posture. 2015;41(2):683–7. doi: 10.1016/ j.gaitpost.2015.01.026 33.gailey rs, roach ke, applegate eb, cho b, cunniffe b, licht s, et al. the amputee mobility predictor: an instrument to assess determinants of the lower-limb amputee’s ability to ambulate. arch phys med rehabil. 2002;83(5):613–27. doi: 10.1053/ampr. 2002.32309 https://doi.org/10.33137/cpoj.v5i1.36847 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 2 2022 research article li w, baddour n, lemaire e.d. a novel quick release mechanism for ankle foot orthosis struts. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.3. https://doi.org/10.33137/cpoj.v5i2.38802 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i2.38802 1 li w, baddour n, lemaire e.d. a novel quick release mechanism for ankle foot orthosis struts. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.3. https://doi.org/10.33137/cpoj.v5i2.38802 research article a novel quick release mechanism for ankle foot orthosis struts li w1, baddour n1, lemaire e.d 2,3* 1 department of mechanical engineering, university of ottawa, ottawa, canada. 2 department of medicine, faculty of medicine, university of ottawa, ottawa, canada. 3 centre for rehabilitation research and development, ottawa hospital research institute, ottawa, canada. introduction an ankle foot orthosis (afo) improves mobility by diminishing foot drop during swing phase and providing gait control during stance.1 a recent advancement in afo design used a posterior strut to store and return energy during movement. an appropriate posterior strut can be selected to accommodate the user’s need for afo stiffness based on their weight and activity level.2,3 however, further functional improvements could be achieved if the person could have different afo stiffness depending on their chosen activity. for example, less stiffness for driving a car, medium stiffness for walking, high stiffness for high-active movements (running, downhill walking etc.). the intrepid dynamic exoskeletal orthosis (ideo) is an energy storing device that supports and protects users following lower extremity limb salvage procedures.4 this afo was crafted with three carbon fiber components: ground reaction cuff for circumferential support providing open access abstract background: a posterior dynamic element ankle-foot orthosis (pdeafo) uses a stiff carbon fibre strut to store and release energy during various mobility tasks, with the strut securely attached to the foot and shank-cuff sections. a design that allows the user to swap struts for specific activities could improve mobility by varying pdeafo stiffness, but current approaches where bolts securely connect the strut to the orthosis make quick strut swapping time-consuming and impractical. objectives: design a novel quick release afo (qrafo) that can enable daily living strut-swapping and thereby enable better ankle biomechanics for the person’s chosen activity. methodology: the novel qrafo enables device stiffness changes through a quick release mechanism that includes a quick-release key, weight-bearing pin, receptacle anchor, and immobilization pin. a prototype was modelled and simulated with solidworks. mechanical tests were performed with an instron 4482 machine to evaluate quick release mechanism strength with running and 20° slope downhill walking loads. quick release efficiency was then evaluated via two quick release functional tests, with four participants wearing a 3d printed qrafo. findings: simulated stress on the weight bearing pin, anchor, and surrounding carbon fibre structure under running and downhill walking loads did not exceed the yielding stress. mechanical tests verified the simulation results. four participants successfully swapped the strut within 25.01 ± 3.66 seconds, outperforming the 60.48 ± 10.88 seconds result for the hand-tightened bolted strut. a learning evaluation with one participant showed that, after approximately 30 swapping iterations, swap time was consistently below 10 seconds. conclusion: the quick release mechanism accommodated running and slope walking loads, and allowed easy and fast strut removal and attachment, greatly reducing strut swap time compared to screw-anchor connections. overall, the novel quick release afo improved strut-swapping time without sacrificing device strength, thereby enabling people to use the most appropriate afo stiffness for their current activity and hence improve mobility and quality of life. article info received: june 15, 2022 accepted: december 4, 2022 published: december 18, 2022 citation li w, baddour n, lemaire e.d. a novel quick release mechanism for ankle foot orthosis struts. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.3. https://doi.org/10.33137/cpoj.v5i2.3 8802 keywords ankle foot orthosis, dynamic gait rehabilitation, multi-stiffness ankle foot orthosis, quick release, orthosis. * corresponding author: edward d. lemaire, phd centre for rehabilitation research and development, ottawa hospital research institute, ottawa, canada. email: elemaire@ohri.ca orcid id: https://orcid.org/0000-0003-4693-2623 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 5, issue 2, article no.3. 2022 https://doi.org/10.33137/cpoj.v5i2.38802 https://doi.org/10.33137/cpoj.v5i2.38802 https://doi.org/10.33137/cpoj.v5i2.38802 mailto:elemaire@ohri.ca https://orcid.org/0000-0003-4693-2623 https://jps.library.utoronto.ca/index.php/cpoj/index 2 li w, baddour n, lemaire e.d. a novel quick release mechanism for ankle foot orthosis struts. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.3. https://doi.org/10.33137/cpoj.v5i2.38802 canadian prosthetics & orthotics journal issn: 2561-987x quick release mechanism for ankle foot orthosis struts li et al., 2022 off-loading to alleviate ankle pain, posterior strut that deforms for energy storage and return, and footplate. the ideo modular design allows strut changes as motion ability changes and can be easier to don and doff.4,5 the posterior dynamic element afo (pdeafo), developed by fabtech systems (everett, wa, usa), is a commercial afo fabricated entirely from carbon fiber. similar to ideo, the pde afo consists of a stiff strut that stores energy during weight loading and stance, and returns the energy during late stance. the strut attaches to the afo shank and sole through bolts, secured with locktite. an anchor system is integrated by laminating a pre-threaded metal plate within the carbon fibre matrix, thereby facilitating strut adjustment while customizing. the strut stiffness and dimensions can be selected to match the user’s activity level. a modularized posterior strut afo design provides possibilities for strut swapping, thereby swapping afo stiffness. however, bolt connections between the strut and afo prevent effective strut changing during the day (i.e., requires tools, more time, etc.). a quick release connection between the strut and afo could be an alternative that enables fast strut-swapping to change stiffness for different activities. the purpose of this research was to develop a novel quick release afo (qrafo) that provides safe and secure energy storage and return, but also allows the qrafo user to swap struts within 30 seconds, to provide appropriate stiffness for their current activity. upon successful simulation, mechanical, and functional tests, the qrafo could be used in daily living to enhance mobility and thereby improve quality of life. quick release mechanism design the new quick release mechanism6 (figure 1) consists of five components: quick release key, weight bearing pin, receptacle, anchor, and immobilization pin. the quick release key is affixed on the strut and the anchor is affixed on the receptacle. a panel between the anchor and quick release key fits the gap between the strut and orthosis when installing thinner struts. the anchor is moulded into the afo. pushing and twisting the quick release key allows the user to pull the strut out of the anchor. a titanium alloy weight bearing pin (ti-pin) bore most of user’s weight during movement. to prevent strut rotation along the weight bearing pin, an immobilization pin (im pin) was included between the quick release key and weight bearing pin. the weight bearing pin was designed to bear all transverse forces on the quick release mechanism (qrm) during movement. titanium alloy ti-6al-4v was selected due to its high yield and ultimate strength. to construct a lightweight device, aluminium 6061 was selected for the anchor. quick release key and receptacle were also made of aluminium 6061 due to its light weight and appropriate strength. the total qrm weight was 30 g. figure 1: quick release afo with quick release mechanism methodology three analyses were performed to assess qrafo strength and functionality. fea simulation was performed on the qrm, including yielding analysis and safety factor analysis under walking load (fatigue load), running load (intense load), and downhill walking load (bending load). mechanical testing was performed on the qrm to analyse the stressdisplacement curve and material deformation. qrm functional testing compared qrm strut swap efficiency to the pdeafo screw-anchor mechanism. strength analysis finite element analysis a qrafo for daily use must not fail during occasional intense activities and long periods of walking. solidworks 2019 (dassault systèmes, vélizy-villacoublay, france) was used to perform finite elements analysis (fea) to simulate the load exerted on the quick release mechanism under three scenarios: level walking, running, and downhill walking (figure 2). the designed device capacity was based on a 120 kg user. shank sole strut anchor im pin receptacle ti-pin panel quick-release key https://doi.org/10.33137/cpoj.v5i2.38802 3 li w, baddour n, lemaire e.d. a novel quick release mechanism for ankle foot orthosis struts. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.3. https://doi.org/10.33137/cpoj.v5i2.38802 canadian prosthetics & orthotics journal issn: 2561-987x quick release mechanism for ankle foot orthosis struts li et al., 2022 figure 2: load and fixture conditions on meshed qrm with two loading types: shearing caused by either walking or running (left); bending caused by landing on uneven ground, representing downhill walking load (right). only shear loads were considered for daily walking and running loads, while bending was included in downhill walking. the 95th percentile canadian male weighs 113.5 kg.7 considering that users may carry personal belongings, a qrafo should withstand daily use by a 1200 n person. peak ground reaction forces for testing were bodyweight for walking,8 3 times bodyweight for running,9 and 1.2 times bodyweight for downhill walking.8 considering the afo cuff off-weighting function (i.e., supporting body weight for some afo applications), the vertical force applied on the qrm was 80% of the peak ground reaction forces.10 the qrm was modelled with virtual jigs (strut to apply load, fixed quick release male components, and shell to fix quick release female components, figure 2). shearing and bending loads were applied to the top of the strut (250 mm long). the shell was globally fixed. since afo devices are suggested to last three years11 with 10,000 walking steps per day as a common goal for adults,12 the qrm should last 107 regular walking cycles. mechanical tests mechanical tests were performed with running and downhill walking loads using an electromechanical testing machine (4482, instronr, norwood, ma) with a 10 kn static load cell (10 n resolution, iso-376, instonr, norwood, ma). 2880 n maximum force was applied at a constant speed of 1 mm/min for the running load and 1080 n maximum vertical force at the same speed for a 20-degree downhill walking load. a special triangular fixture with a surface angle of 20 degrees was machined to apply a moment to the quick release mechanism (figure 3). the load cell initial position was manually set to approximately one millimetre from the iron shell. a smartphone was fixed on a tripod to video record the trials. when the force sensed by the load cell reached the maximum load or the displacement reached 10 mm, the load cell terminated action and returned to the origin position. ten trials were collected and analysed for each test. the instron machine recorded data at 10 hz. after testing, the force-displacement relation was explored by analysing the slope of the curve. quick release component dimensions were measured by a caliper (accusize industrial tools, ab11-1106) before and after testing to determine if surface damage occurred between the ti-pin and aluminum anchor. figure 3: anchor fixed to vertical loading strut (i.e., represents shank connection) (a); quick release key and weight bearing pin fixed to clamp (i.e., represents foot-ankle unit connection) (b); testing setup for running load (c); downhill walking load with angled loading plate (d). functional analysis two afos were 3d printed for the functional analysis. the two afos had identical components but different connection mechanisms: one with the quick release mechanism and another with a pdeafo screw-anchor mechanism. while screws are typically secured using d c a b loading plate loading plate https://doi.org/10.33137/cpoj.v5i2.38802 4 li w, baddour n, lemaire e.d. a novel quick release mechanism for ankle foot orthosis struts. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.3. https://doi.org/10.33137/cpoj.v5i2.38802 canadian prosthetics & orthotics journal issn: 2561-987x quick release mechanism for ankle foot orthosis struts li et al., 2022 locktite to ensure that the strut does not loosen, the screws were hand tightened for this test to enable comparison. four able bodied participants were recruited (3 males, 1 female). ethical approval was received from the university of ottawa research ethics board (file number h-10-194767). all participants provided informed consent. while sitting on a chair, participants donned the afo with quick release mechanism. after self-finding a comfortable position, the participant removed the strut, waited 2 to 4 seconds, and then reattached the strut. this swap trial was performed 10 times. then, the participant donned the afo with the screw anchor mechanism and repeated the swap trial 10 times. all swap trials were recorded with a gopro camera (san mateo, california, usa) affixed on a tripod. all participants were asked to adjust their posture and position to provide a clear side view to the camera. to investigate the learning process for strut swapping, one participant performed the strut swap trial 50 times for each device. the time to complete each strut removal and each strut attaching were extracted from the digital video using matlab r2019b (mathworks, natick, massachusetts, usa). strut removal started when the hand touched any strut component and ended when all strut components were not contacting the afo. strut removal with the screwanchor connection started when the screwdriver touched any strut component and ended when all strut components were not contacting the afo. strut attaching with the qrm started when any strut component touched the afo and ended when hand not contacting the afo. strut attaching with the screw-anchor connection started when any strut component touched the afo and ended when the screwdriver was not touching any strut components. results fea simulation the modified goodman equation was used to calculate the safety factor of fatigue given by: 𝜎𝑎 𝑆𝑒 + 𝜎𝑚 𝑆𝑢𝑡 = 1 𝑛 (1) where 𝜎𝑎 is the amplitude component of stress, 𝜎𝑚 is the midrange stress component, se is the fatigue strength, and sut is the ultimate strength and n is the safety factor. the fatigue strength of aluminium is 117 mpa and grade 5 titanium is 280 mpa.10 figure 4 shows the stress distributions over qrm components with the three loads. by assuming the amplitude and midrange stress are equal (i.e., half the maximum stress) the safety factor to fatigue under walking load was 5.09 for the weight bearing pin and 1.37 for the anchor. compared with the ti-pin (880 mpa) and anchor (270 mpa) yielding strengths, yielding safety factors were 5.5 for the ti-pin and 1.07 for the anchor with running load. downhill walking load produced more stress on the components, with yielding safety factors of 1.17 for ti-pin and 1.02 for anchor. the bending force also generated a pulling force on the quick release key and receptacle, with safety factors of 10.38 for the quick release key and 6.14 for the receptacle. (a) (e) (b) (f) (c) (g) (d) (h) figure 4: simulation results for qrm components: stress distributions of weight bearing pin with (a) walking load; (b) running load; (c) downhill walking; (d) stress distribution of quick release key with downhill walking load; (e) stress distributions of anchor with walking load; (f) running load; (g) downhill walking; and (h) stress distribution of receptacle with downhill walking load. https://doi.org/10.33137/cpoj.v5i2.38802 5 li w, baddour n, lemaire e.d. a novel quick release mechanism for ankle foot orthosis struts. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.3. https://doi.org/10.33137/cpoj.v5i2.38802 canadian prosthetics & orthotics journal issn: 2561-987x quick release mechanism for ankle foot orthosis struts li et al., 2022 mechanical testing results from the mechanical tests, force-displacement analysis indicated no yielding with running and downhill walking loads, demonstrated by the curve increasing monotonically (figure 5). the qrm materials were in their elastic region when the maximum loads were applied. figure 5: force-displacement curves from running load test (top) and downhill walking load test (bottom). pearson correlation coefficients between force-displacement curves were larger than 0.99. therefore, both running and downhill walking load tests were repeatable. table 1 shows the mean and standard deviation of the measured dimensions before and after testing. the mean ti-pin diameter (6.29 mm), ti-pin length (21.10 mm), and anchor hole diameter (6.38 mm) were within 0.02 mm of their original dimensions. standard deviations were smaller than 0.02 mm, so measurements along one surface were consistent. therefore, surfaces were not damaged due to running and downhill walking loads. table 1: means and standard deviations (mm) of the original ti-pin diameter, length, and anchor hole diameter dimensions. dimensions are before testing, after running load, and after downhill walking load tests. before testing running load downhill load ti-pin diameter (mm) 6.29 (0.01) 6.29 (0.02) 6.28 (0.01) ti-pin length (mm) 21.10 (0.01) 21.11 (0.01) 21.09 (0.01) anchor hole diameter (mm) 6.37 (0.01) 6.38 (0.01) 6.38 (0.01) quick release efficiency test the average swap time across the four participants with qrm was 25.01 ± 3.66 seconds. all participants swapped the strut within 30 seconds, on average (figure 6). the best swap time was 13.83 ± 3.08 seconds and the worst swap time was 53.82 ± 18.90 seconds, among all participants. as a comparison, the average screw anchor mechanism swap time was 60.48 ± 10.88 seconds, 142% longer than qrm swap time. the best swap time was 38.71 ± 3.43 seconds, 180% longer than swap with qrm and the worst swap time was 98.23 ± 22.19 seconds, 83% longer than swapping with qrm. all participants failed to swap screw anchor mechanism struts within 30 seconds (figure 6). figure 6: range and mean of total swap time for qrm and screw anchor connection. strut swap learning for the participant who completed the 50 trial test, the average swap time with the qrm was 13.85 ± 6.52 seconds f o rc e m e a s u re d f ro m l o a d c e ll (n ) mean standard deviation mean standard deviation displacement after touching point (mm) displacement after touching point (mm) f o rc e m e a s u re d f ro m l o a d c e ll (n ) range and mean of total swap time of qrm range and mean of total swap time of screw anchor mechanism participants participants t o ta l s w a p t im e ( s ) t o ta l s w a p t im e ( s ) maximum swap time average swap time minimum swap time maximum swap time average swap time minimum swap time 30 second criterion 30 second criterion https://doi.org/10.33137/cpoj.v5i2.38802 6 li w, baddour n, lemaire e.d. a novel quick release mechanism for ankle foot orthosis struts. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.3. https://doi.org/10.33137/cpoj.v5i2.38802 canadian prosthetics & orthotics journal issn: 2561-987x quick release mechanism for ankle foot orthosis struts li et al., 2022 and with the screw-anchor was 58.41 ± 11.16 seconds. as the participant learned how to best swap the strut, swap time improved from a maximum of 35.95 seconds to 6.81 seconds. figure 7 shows the learning effect since strut swapping time decreased over the first 30 trials. the first ten strut swaps averaged 23.97 seconds and the last ten swaps averaged 8.92 seconds. standard deviation also improved, with a standard deviation of the first ten trials of 5.22 seconds and the last ten trials of 1.43 seconds. figure 7: time to swap strut with qrm and screw-anchor mechanism; including, strut removal time, strut attaching time, and total strut swap time. less time was needed to remove the strut than attach the strut. the average time to remove the strut, over the first ten trials, was 4.27 ± 0.68 seconds and over the last ten trials was 2.68 ± 0.82 seconds (37.2% decrease). qrm swapping time was much less than the 30-second design criteria. in comparison, the screw-anchor mechanism averaged 58.41 ± 11.16 seconds to swap. a milder learning effect was seen on screw anchor mechanism swapping (figure 7). the average time to swap the strut for the first ten trials was 73.39 ± 7.98 seconds, including a mean attaching time of 50.37 ± 4.71 seconds and a mean removing time of 23.01 ± 6.23 seconds. the average time to swap the strut for the last ten trials was 47.85 seconds, with a mean attaching time of 33.07 seconds and a mean removing time of 14.78 seconds. the time decrease in total swap time between the first ten trials and last ten trials was 34.8%, including a 34.3% decrease in attaching and 35.8% decrease in removing. standard deviations were also larger than the qrm results. the standard deviation of the first ten trials was 7.98 seconds, and the last ten trials was 3.74 seconds. more time was required to swap struts when using an afo with the screw-anchor mechanism, and the 30-second swapping criterion was not achieved. discussion a new quick release mechanism was successfully designed and prototyped to enable a person using a posterior-strut style afo to quickly swap the strut, enabling different strut stiffnesses that would better relate to the person’s chosen activity. swap time was below the 30 second target, and with practice can be consistently below 10 seconds. since the qrm strut can be swapped without tools, this mechanism has a greater potential to be used in daily living than approaches requiring screw drivers or other tools. mechanical testing revealed that the qrm could bear running and downhill walking loads for a 120 kg person with no failure from material or connections. force-displacement curve analysis revealed that qrm materials remained in their elastic region under the maximum target loads. the ten trials showed high repeatability, indicating that the connection was not failing (slipping, dislocating, etc.) under running and downhill walking loads. titanium did not harm the aluminum anchor’s surface, inferred from low dimension variation between trials. all qrm component safety factors under walking loading, running load, and downhill walking load were greater than one. the lowest safety factor was for walking on a 20degree descending hill; however, the mechanical test forcedisplacement results gave confidence in the design since no plastic deformation occurred under maximum running or downhill walking loads. as well, the ti-pin did not damage the aluminum anchor surface under large loads since the weight bearing pin and anchor dimensions did not change after each test. pearson correlation coefficients between trials were close to 1, reflecting high similarity between trials from the same test. while the evidence proved that the qrm can withstand a range of daily activity loads, safety factors close to the yielding margin for highly active users such as athletes would require further testing to verify the qrafo loading parameters under higher loading conditions. qrm functional tests revealed that participants can quickly swap struts while sitting. the time was substantially lower than the screw-anchor mechanism swap time. during testing, participants spent more time at the beginning and tended to swap faster after they became accustomed to the swap method and posture. after learning, a user can swap struts in under 10 seconds and with less variability, which outperformed our design criteria. the actual swap time could be much less than we observed in experiments since afo users would have many more swap instances over the years of afo use. time to swap strut with qrm time to swap strut with screw anchor mechanism trial trial t im e ( s ) t im e ( s ) remove the strut attach the strut total swap time remove the strut attach the strut total swap time https://doi.org/10.33137/cpoj.v5i2.38802 7 li w, baddour n, lemaire e.d. a novel quick release mechanism for ankle foot orthosis struts. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.3. https://doi.org/10.33137/cpoj.v5i2.38802 canadian prosthetics & orthotics journal issn: 2561-987x quick release mechanism for ankle foot orthosis struts li et al., 2022 various limitations should be considered for this study. under extreme cold weather, the high thermal conductivity of aluminum alloy can result in the metal components being cold to the touch when swapping struts. due to the high tolerance of the ti-pin and anchor, if small particles such as sand stay inside the anchor more push and pull force could be required while swapping struts and may damage the anchor hole inner surface with prolonged wear. this issue can also occur for muddy roads since mud could stay in the anchor hole, thereby leading to difficulty while swapping struts. these conditions could be mitigated with a proper device cleaning regiment. though functional tests successfully verified qrm function on a 3d printed afo, qrm performance with a complete carbon fibre posterior strut afo was not evaluated. further testing with a larger sample size is required to confirm qrm performance in daily living environments. conclusion in this research, the quick release strut swapping system of a novel qrafo was designed and evaluated. the quickrelease mechanism allows individuals with dorsiflexor/ plantarflexor weakness to tune their afo to their daily activities, such as driving, walking, downhill walking, and running. this design was low profile allowing the orthosis to fit beneath regular clothing. the weight added to the strut is minimal, which motivates users to carry extra struts with different stiffness levels for use during the day, or have various stiffness struts in their car, sport bag, or at work. simulation and mechanical tests demonstrated that the components should withstand running and downhill walking loads. functional testing showed that people could swap struts quickly, thereby encouraging use in daily living. future research should evaluate qrafo use with current posterior strut afo users. acknowledgements this project was funded by natural sciences and engineering research council of canada (nserc). the qrafo was developed in consultation with the staff of the ottawa hospital rehabilitation centre, with special acknowledgement to patrick lebel and paul nichols. declaration of conflicting interests the authors report no conflicts of interest to disclose. authors contribution wentao li: conceptualization, design, methodology, analysis, investigation, writing original draft, data interpretation, ethic certification application. natalie baddour: conceptualization, supervision, methodology, reviewing/revising manuscript, final manuscript approval. edward d. lemaire: conceptualization, supervision, methodology, reviewing/revising manuscript, final manuscript approval. sources of support this project was funded by natural sciences and engineering research council of canada (nserc). ethical approval the study was approved by the university of ottawa research ethics board, university of ottawa, canada. signed informed consent was obtained from each participant before commencing. references 1.introduction to ankle foot orthoses [internet]. physiopedia; [cited: 2022 nov 25]. available from: https://www.physiopedia.com/introduction_to_ankle_foot_orthoses. 2.highsmith mj, nelson lm, carbone nt, klenow td, kahle jt, hill ot, et al. outcomes associated with the intrepid dynamic exoskeletal orthosis (ideo): a systematic review of the literature. mil med. 2016;181(suppl_4):69-76. doi: 10.7205/milmed-d-1600280 3.bedigrew km, patzkowski jc, wilken jm, owens jg, blanck rv, stinner dj, et al. can an integrated orthotic and rehabilitation program decrease pain and improve function after lower extremity trauma? clin orthop relat res. 2014;472(10):3017-25. doi:10.1007%2fs11999-014-3609-7 4.patzkowski jc, blank rv, owens jg, wilken jm, blair ja, hsu jr. can an ankle-foot orthosis change hearts and minds? j surg res orthop adv. 2011; 1. 5.patzkowski jc, blanck rv, owens jg, wilken jm, kirk kl, wenke jc, et al. comparative effect of orthosis design on functional performance. j bone jt surg. 2012;94(6):507-15. doi: 10.2106/jbjs.k.00254 6.li w, lemaire ed, baddour n. design and evaluation of a modularized ankle-foot orthosis with quick release mechanism. in 2020 42nd annual international conference of the ieee engineering in medicine & biology society (embc) 2020 jul 20; 4831-4834. 7.measured weight, by age and sex, household population, canada, 2009 to 2011 [internet]. statistics canada; [cited: 2022 nov 30]. available from: https://www150.statcan.gc.ca/n1/pub/82626-x/2013001/t024-eng.htm. 8.redfern ms, dipasquale j. biomechanics of descending ramps. gait & posture. 1997; 6(2):119-25. doi:10.1016/s0966-6362(97) 01117-x 9.clark kp, ryan lj, weyand pg. a general relationship links gait mechanics and running ground reaction forces. cambridge (uk): j exp biol. 2017;220(2), 247-258. doi: 10.1242/jeb.138057 10.li w. development and evaluation of a quick release posterior strut ankle foot orthosis. ottawa (ca); thesis, université d’ottawa / university of ottawa; 2020. 11.how often do i need to change my orthotics? [internet]. applied biomechanics; [cited: 2022 aug 14]. available from: https://appliedbiomechanics.com/orthotics-bracing-blog/oftenneed-change-orthotics/ . 12.tudor-locke c. how many steps/day are enough? preliminary pedometer indices for public health. sports med. 2004;34(1):1-8 doi: 10.2165/00007256-200434010-00001. https://doi.org/10.33137/cpoj.v5i2.38802 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.35972 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 stakeholder perspectives (in) access to artificial limbs: the patient’s perspective according to the war amps of canada petlock a.*, dimario k. advocacy program, the war amputations of canada, ottawa, canada. introduction the average canadian would be shocked to know that if they or a family member lose a limb, they could be faced with a personal balance of thousands of dollars for even the most basic artificial limb that will restore only a semblance of their previous function. insufficient access to funding for artificial limbs is a key barrier faced by canadians with amputations. across the country, both public and private funding agencies create and adhere to policies that do not reflect the reality of living with amputation and that, when applied, prevent amputees from being able to access prosthetic care that is medically prescribed and essential to their everyday functionality. for those who cannot afford to pay thousands out of pocket, few alternatives exist. for many, crowdfunding has proven necessary, a veritable canary in the coal mine pointing to a distressing state of affairs for canada’s healthcare system. it is also only a stop-gap solution, given that amputees will understandably be reluctant or simply unable to repeatedly appeal to friends and family for the subsequent replacement limbs they will need during their lifetime. it is unimaginable in the 21st century that seriously disabled amputees would have to rely on their families and communities in this way to cope with the basic financial requirements. the purpose of this paper is to highlight the nature of the issues in the public and private realms, describe the attitudinal and legislative barriers that perpetuate these issues and suggest mechanisms for how patients, professionals and the public can work together to improve access to funding for artificial limbs, and, as a result improve the lives of canadian amputees. 1. funding for artificial limbs in canada: a multi-level battlefield across the country, there are over 40 public and private agencies that provide funding for artificial limbs. these range from federal, provincial and municipal governments to workers compensation regimes, employment and private insurance companies and charitable agencies, including the war amps of canada. although there are various open access volume 4, issue 2, article no.13. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract funding agencies, both public and private, do not adequately meet the needs of canadian amputees. this often leaves amputees without access to appropriate prosthetic care due to outstanding balances that are to be paid out of pocket, or by charitable organizations. there are several factors that result in these inadequacies. as healthcare is a provincial responsibility in canada, provinces and territories have the authority to create individual public regimes, each with their own weaknesses. in fact, there are a few provincial regimes which do not include prosthetic funding at all. private healthcare is meant to offset the remaining balance; however, their lack of knowledge regarding amputation has resulted in the creation of policies with ambiguous language, limiting the funding available for prosthetic care. attitudinal barriers and missed legislative opportunities further exacerbate the shortcomings of prosthetic funding provided by public and private funding agencies, requiring action. citation petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 keywords health economics, prosthetic care, artificial limb, funding agencies, insurance, public healthcare * corresponding author annelise petlock the war amps advocacy program/ 2827 riverside drive ottawa, ontario, canada. e-mail: annelise.petlock@waramps.ca orcid id: https://orcid.org/0000-0002-7273-4527 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.35972 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.35972 mailto:annelise.petlock@waramps.ca https://orcid.org/0000-0002-7273-4527 2 petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 issn: 2561-987x (in) access to artificial limbs: the patient’s perspective petlock & dimario, 2021 cpoj special s p e c ia l i s s u e agencies that provide funding towards the cost of artificial limbs, the funding received from even one source does not adequately support the average amputee in canada. generally, persons with amputations have three potential routes to access funding for prosthetic care (excluding crowdfunding): provincial healthcare funding, private insurance, and charitable sources. other than small grassroots and locally based amputee groups like the ottawa amputee society, the war amps is the only large charitable organization in support of amputees in canada. the war amps, a charitable organization that does not receive government grants, fills the gaps in funding where it can; however, as a charitable organization that relies on public donations, these funds can only go so far. as such, the war amps mandate stipulates that funding can only be accessed after other government and insurance agency contributions are exhausted. unfortunately, provincial healthcare and private insurance regimes miss the mark, leaving large outstanding balances to be funded by the amputee themselves or a charitable organization. table 1: provincial funding issues. province(s) description of funding issues newfoundland and new brunswick no funding available unless in receipt of social assistance. working residents receive no provincial support for artificial limbs. for those receiving social assistance, the maximum provincial contribution is often insufficient to cover the total cost of the prosthesis. prince edward island no policy exists. amputees receive coverage if they receive care at the one public prosthetic clinic in the province. no coverage is available if they receive care elsewhere. nova scotia limited funding is available. if prosthetic care is received at the one publicly run centre in the province, then full coverage is possible. wait times are extensive. when care is received at a private clinic, the province covers approximately 1/3 of the cost. quebec some funding available according to a fee schedule. fee schedule is extremely outdated and includes items that are no longer prescribed and excludes basic prosthetic components. if persons with amputations require components not listed on the fee schedule, then they receive no provincial funding. all components must be from their approved list or no coverage is received. ontario some funding available according to a fee schedule which has not been updated since 2006. fee schedule includes items no longer prescribed and excludes basic prosthetic components. still, ontario claims to cover 75% of prosthetic care costs, but since the fee schedule is badly outdated, it is often typically 10-30%. manitoba funding is available. lack of transparency for what is covered. no written policy is available. no updates have been made to the fee schedule in many years and there is no mechanism for ongoing updates to policy or fee schedule. saskatchewan funding is available and generally covers what is required for amputees. care is only offered in two centers in the province leading to long wait times. if care is required sooner, often amputees choose to go out of province (to alberta). if they do so, coverage can be less than 1/3 of the cost. alberta funding is currently available. on dec 23, it was announced that private insurance must be exhausted before provincial support can be accessed, which is unusual, unprecedented and will generate significant complexity in 2021. in addition, fee schedules for reimbursement amounts for prosthetic componentry are outdated and not reflective of current cost structures. movement toward privatization may bring further regression and spur some of the issues with the insurance industry we are familiar with. yukon and the territories persons with amputations living in remote communities’ travel to the nearest prosthetic clinic in a neighboring province. territories generally cover the cost of care and the travel out of province. the issues arise when we attempt to locate policies or standards which govern the decisions to approve or deny prosthetic care: none appear to exist. hence, amputees are faced with ambiguity about whether the territory will cover the cost of care. we have seen circumstances where standard care seems to be arbitrarily denied, with no policy basis. british columbia funding is limited to items that restore “basic functionality”. this term is ambiguously defined, narrowly applied, and fails to realize that artificial limbs do not provide functionality equivalent to the missing limb. as a result, prosthetic care and componentry that is considered “standard” by the prosthetic profession, industry and medical community are arbitrarily excluded. for example, myoelectric hands, which have been an integral aspect of prosthetic care for over 30 years are not covered. due to the ambiguous definition, there is uncertainty regarding what will be and what will not be covered from fitting to fitting. https://doi.org/10.33137/cpoj.v4i2.35972 3 petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 issn: 2561-987x (in) access to artificial limbs: the patient’s perspective petlock & dimario, 2021 cpoj special s p e c ia l i s s u e 1.1. public healthcare in canada due to canada’s constitutional framework, healthcare is a provincial responsibility. the canada health act mandates that all provinces must cover the cost of “essential healthcare services”, defined as those administrated by doctors in hospitals. anything outside of essential services are deemed to be provided “at the discretion of the province”. as a result, provinces and territories in canada have used their discretionary authority to create no less than 13 different public regimes for covering the cost of prosthetic care (one for every province and territory). each one of these systems fails, in a unique (and creative) manner to adequately respond to the reality of living with amputation and relying on prosthetic care. as a result, the lack of access to quality mobility aids, devices and assistive technology at an affordable cost remains a barrier to accessibility for canadian amputees. see table 1, for an overview of how these systems fail to meet the mark. 1.2. case examples ontario the outdated fee-schedule utilized by ontario’s assistive devices program (adp) leaves many amputees with a large outstanding balance to fund out-of-pocket. see table 2 and table 3 below for an overview of the lack of coverage provided by adp. table 2: adp coverage for an above knee prosthesis with a microprocessor knee unit. cost of prosthesis: $56,102.42 adp amount covered: $12,286.00 remaining balance: $43,816.42 percentage of adp coverage: 21.9% table 3: adp coverage for the replacement of a left below elbow myoelectric socket due to growth. cost of prosthesis: $7,701.06 adp amount covered: $2,188.00 remaining balance: $5,513.06 percentage of adp coverage: 28.4% saskatchewan a five-year-old bilateral above the knee child amputee was unable to receive timely and effective treatment in saskatchewan. they were forced to seek care at a centre with more experience with children and multiple amputations out of province. as prosthetic treatment was obtained out-of-province, the province offered reimbursement just over $6,000 towards the total cost of the prescribed bilateral transfemoral prosthesis just over $20,000. british columbia the british columbia ministry of health issued approvals for a number of amputees to receive osseointegration surgery in australia. after they received the surgery, they returned to bc to find that the province refused to cover the cost of their prosthesis. pharmacare, a branch of the ministry of health explained that there was no policy to cover the cost of osseointegration prosthetic care. the amputees who received the surgery, paid for by the province, were left with no coverage for their prosthesis for nearly a year. most provinces offer some coverage for artificial limbs, but each system has serious flaws, which move away from a patient centered approach, and regularly negatively impact the health and well-being of a very vulnerable group of canadians, persons with amputations. amputation and prosthetic care are a complex and highly specialized area of healthcare. thus, provinces may be generally unaware of how badly they are failing canadian amputees. for this reason, it is important for public funding agents to be informed of the reality of living with amputation, and the ways in which their failures impact amputees. 1.3. private funding for prosthetic care to supplement inadequate provincial healthcare funding, the insurance industry plays a large role in providing funding for artificial limbs in canada. unfortunately, the insurance industry lacks federal or provincial legislation which builds in protections for vulnerable groups like amputees who require insurance funding for adequate prosthetic care. hence, the diversity of insurance policy framework is even more vast than public funding frameworks. as the variety of insurance policy language that pertains to artificial limb coverage is studied, findings suggest that the arrow misses the target by immeasurable margins, with insidious results. table 4 highlights the arbitrary language utilized in insurance policies which contribute to inadequate prosthetic funding. 2. attitudinal barriers in studying this issue, findings suggest a number of key attitudinal barriers that act to compound, perpetuate, and reinforce insufficient access to funding for artificial limbs. both the canadian public and key stakeholders including insurers, and government agents exhibit a lack of understanding of a very complex area of health care and medicine, underestimate the cost of prosthetic technology, and assume that prosthetic technology is more advanced than it is, also known as sci fi syndrome. https://doi.org/10.33137/cpoj.v4i2.35972 4 petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 issn: 2561-987x (in) access to artificial limbs: the patient’s perspective petlock & dimario, 2021 cpoj special s p e c ia l i s s u e 2.1. lack of understanding into a complex area of healthcare government agencies and insurance companies do not fully comprehend the impact of amputation and the role the prosthesis plays in reducing the incidence of other medical conditions that can develop with amputation. adequate prosthetic care will also assist in restoring some of the functionality required for them to access services in, and contribute to, their community and workplace. if an amputee does not have access to the proper prosthesis or develops repetitive strain injuries as a result of a lack of appropriate prosthetic care, the potential cost to the governments and insurers could be immense.1,2 while the up-front cost of an appropriate, medically necessary prosthesis appears expensive, in the long term it will save costs.3 prostheses have been demonstrated to increase safety and security, and to reduce the incidence of the comorbidities associated with amputation. subsequently, a decrease in comorbidities translates to a decrease in the costs associated with those comorbidities, which include but are not limited to expensive medication for mental health and pain management, paramedical treatments, treatment for injuries caused by falls, the cost of home modifications, vehicle modifications and daily living aids, as well as additional income replacement costs as the individual is not able to return to work without the appropriate prosthesis. public and private funding agencies do not realize the above when they build limiting prosthetic policies or issue coverage denials. indeed, the choice is to pay now for the prosthesis, or pay later for the comorbidities. of course, it is the amputee who pays the most. 2.2. underestimate the cost of prosthetic care the canadian public is generally unaware of the often prohibitively high cost of artificial limbs. they assume that costs are only a fraction of the actual cost and do not understand the unique nature of the prosthetic industry. for example, prostheses have a very custom nature to reflect the needs of each individual amputee and their level of amputation, and the engineering of prosthetic components requires significant research and development to ensure functionality. as a result of this lack of understanding, public and private agencies balk at the cost. “sticker shock” can trigger denials, and this coupled with sci fi syndrome, described below, creates attitudinal barriers to access funding for care. in addition, the canadian public often assumes that artificial limbs are fully covered by provincial funding agencies. as canadians give credit to provinces for care they do not provide, this “credit” further reduces the incentive to make meaningful improvements to prosthetic funding. table 4: arbitrary policy phrasing. policy phrasing explanation “one limb for life” children grow, people have weight fluctuations and components break or wear out. people need replacement artificial limbs roughly every three years. one artificial limb for life is not reflective of the reality of amputation and prosthetic care. $1,000 maximum with costs for prostheses ranging from $8,000 to $100,000, this amount is grossly insufficient. no direct billing or “assignment of benefits” few people have $8,000 to $100,000 in liquid assets or credit that they can use to purchase their prosthesis and then wait for reimbursement. for this small demographic, there must be some arrangement where the provider can be paid directly. “myoelectrical limbs are excluded” myoelectric hand technology is over 40 years old, yet this clause remains common. we suspect that these exclusions were put in place when this technology was new, but after 40 years, it is time for an update. in application, insurers will commonly deny other prosthetic care on the ground that it is myoelectric, when it is not (such as a microprocessor-controlled knee unit). a myoelectric-controlled prosthesis is an externally powered (i.e. powered by battery) artificial limb that uses the existing muscles in a person’s residual limb to control its functions; however, a microprocessor-controlled knee unit is a body-powered component (i.e. the forces and movement generated come from the user of the device) that allows the knee position to change slightly by adjusting hydraulic resistance levels to support stability when standing, and when on slopes and/or uneven terrain. unreasonable and rigid replacement frequency limits: 5 years, no exception a lot can happen in five years and these policies offer no room for accommodation. if an amputee experiences volume fluctuation due to a pregnancy, a revision surgery or growth (as in the case of children), they may be precluded from receiving their insurance support for a number of years. “subject to usual and customary limits” this is perhaps the most pernicious phrase to the amputee seeking private insurance to help cover the cost of their prosthetic care. often, insurers will approve coverage for prosthetic care “subject to usual and customary limits” as defined by their internal polices. in application, this means that an amputee seeking coverage for their $60,000 prosthesis, which may have coverage of 80% written in their policy, may be shocked when they submit their receipt to insurers and the insurer indicates that $5,000 is the “usual and customary limit”. the insurer will not pay a penny more. https://doi.org/10.33137/cpoj.v4i2.35972 5 petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 issn: 2561-987x (in) access to artificial limbs: the patient’s perspective petlock & dimario, 2021 cpoj special s p e c ia l i s s u e 2.3. sci fi syndrome hollywood and the media have raised the expectation of what is possible in prosthetic technology in the eyes of the public, the amputee and their support system, and the funding agencies. all too often, the realities fall short of these expectations, which can have a devastating impact on the amputee and their rehabilitation. the images, the terminology, the stories, and the hype all contribute to the unrealistic expectations. a number of movies and television shows have featured artificial hands that have more basis in special effects than real prosthetic technology available to the consumer: star wars; robocop; terminator; the six-million dollar man, and more. through entertainment in television, these portrayals set false expectations of the functionality of prosthetic devices, allowing us to ignore the limitations of them. as a result, given the lack of familiarity with prosthetic limbs or with amputation, the public and policy decisionmakers often assume that prosthetic limbs provide more functionality than the reality. sometimes, even assuming that they can offer functionality “greater than the real limb”. in response to this assumption, decision-makers often assert that the amputee only needs “a basic limb” and not anything “sophisticated”. they do not realize that in truth, no technology available today comes close to replicating functionality lost with the loss of a limb. the “sci fi syndrome” mentality negatively affects amputees by limiting access to technologies which will prevent them from falling, reduce overuse and strain injuries, or help them to maximize their functional ability. in order for amputees to have access to funding, we must overcome these attitudinal barriers held by the canadian public, and public and private funding agencies, which are reinforced by hollywood and the media portrayals. 3. legislative opportunities current legislative frameworks that could ensure access to funding for prosthetic care are underutilized. underutilized legislative frameworks is a contributing factor to the failure of the canadian system to provide appropriate prosthetic funding. despite canada’s role as a signatory to the united nations convention on the rights of persons with disabilities, and recent steps to enhance and define accessibility legislation, canada still lags significantly behind other comparable countries and persons with amputations continue to be unprotected by high level legal mechanisms. 3.1. united nations convention on the rights of persons with disabilities internationally, it is the war amps’ position that canada is in violation of its international obligations under the united nations convention on the rights of persons with disabilities. article 20 of this convention has set out that state parties must take steps to facilitate access to quality mobility aids, devices, and assistive technologies, including making them available at affordable costs. “states parties shall take effective measures to ensure personal mobility with the greatest possible independence for persons with disabilities, including by: • facilitating the personal mobility of persons with disabilities in the manner and at the time of their choice, and at affordable cost; • facilitating access by persons with disabilities to quality mobility aids, devices, assistive technologies and forms of live assistance and intermediaries, including by making them available at affordable cost;” 4 further, article 32 states that state parties will: • “[provide], as appropriate, technical and economic assistance, including by facilitating access to and sharing of accessible and assistive technologies, and through the transfer of technologies.” 5 canada ratified this convention in 2010, while seeming to completely overlook this obligation. amputees, and others who rely on assistive technology for their mobility, do not have access to the mobility aids they need at an affordable price. canada’s failure to appropriately fund artificial limbs for amputees is even more shameful when we consider that the world health organization (who) has identified artificial limbs as a “priority assistive product” through the gate initiative (global co-operation on assistive technology). the priority assistive product list serves as a model for member states to build their own priority areas and implement by priority. also included on this list are hearing aids, wheelchairs, communication aids, spectacles, pill organizers and memory aids, among others. in collaboration with the convention, the who is clear that assistive technologies like artificial limbs should form an integral part of universal health coverage for state parties who have ratified the convention. as we know, this is simply not so in canada. if canada were to truly follow through on their commitment as a signatory to this convention, it is our position that they would be obligated to make sweeping changes to funding for artificial limbs across the country. as it stands, this convention remains an important and underutilized tool to improve funding for artificial limbs in canada. 3.2. accession to the optional protocol to united nations convention on the rights of persons with disabilities as of december 2018, canadians can make a complaint directly to the united nations if it is felt that their rights as https://doi.org/10.33137/cpoj.v4i2.35972 6 petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 issn: 2561-987x (in) access to artificial limbs: the patient’s perspective petlock & dimario, 2021 cpoj special s p e c ia l i s s u e indicated by this convention have been violated.6 if the united nations committee feels the complaint has merit, they can conduct an investigation and make an order to compel the state party (the country) to comply.7 before this tool for change can be leveraged, we must “exhaust all domestic options”, which means we must pursue opportunities for change and improvement at the provincial and federal level. if this is done with no improvement, then a complaint can be mounted to the united nations. hence, as part of the war amps’ crusade for reform for prosthetic funding, we are holding all funding agencies to account and working to advise of the issue and, case by case, challenge inadequate funding. in the next few years, if we do not see meaningful change, we intend to appear before the united nations committee on behalf of canadian amputees. as a registered non-governmental organization within the economic and social council of the united nations, the war amps has a long history of leveraging united nations convention optional protocols to ensure that the rights of canadians are upheld. since the first world war, we have fought to protect the rights of amputees and veterans and address the inequities they face. in that time, we have taken on many important battles in support of amputees and our veterans, including: hong kong veterans and victims of thalidomide. hong kong veterans in 1987, the war amps, in association with the hong kong veterans’ association of canada, petitioned the united nations commission on human rights to demand compensation to canada’s hong kong prisoners of war following the “gross violation of human rights” committed by the government of japan during the second world war, which has caused devastating and lifelong health impacts. the government of japan did not respond favourably. thus, the war amps targeted the canadian government for its failure to protect the interests of the hong kong veterans as part of the peace treaty entered into between allied countries (including canada) and japan following the second world war. hence, the war amps initiated a communication under the optional protocol of the international covenant on civil and political rights alleging a form of discrimination exercised by canada in its failure to protect the interest of the hong kong veterans’ prisoners of war against japan. the war amps successfully entered into negotiations with the canadian government and worked out a financial settlement which resulted in appropriate compensation being paid in the form of an ex-gratia payment from the canadian government to the individual hong kong veterans. victims of thalidomide the war amps, along with the thalidomide victims association of canada, also sought proper compensation from the commission on human rights for canada’s thalidomide victims (survivors) as a direct consequence of the federal government’s distribution of the drug in canada. thalidomide was administered to pregnant women in canada, which resulted in well over 100 children being born with birth defects and serious medical issues, which they continue to confront today. in september 1989, the war amps petitioned the united nations human rights committee under the optional protocol pursuant to the international covenant on civil and political rights. the petition led to direct negotiations with the federal government and, more particularly, the ministry of health, resulting in a settlement which addressed the plight of the thalidomide survivors to that point in time. unquestionably the triggering of the optional protocol under the international covenant on civil and political rights was a key element to having the thalidomide victims claim recognized by the canadian government. in both instances, the war amps exhausted legal remedies in canada, and yet, no justice had been served. it was only by leveraging these optional protocols that these very vulnerable groups received the support and compensation they needed to move forward after such devastation. 3.3 federal government inaction there are many ways the federal government, in conjunction with the provinces, can ensure that canada is meeting its international obligation to provide affordable access to prosthetic care. they must: 1. set a national standard for appropriate prosthetic funding at the provincial level. 2. build legislation to prevent insurers from being able to create and sell insurance policies that have arbitrary caps on prosthetic funding. 3. include considerations for access to funding into accessibility legislation. a national standard for prosthetic funding as evidenced from the above, canada is lacking a national standard which facilitates access to assistive technologies at an affordable cost, for persons with disabilities. such standards have been implemented in other countries. this includes but is not limited to germany, australia, and england. germany transitioned to a national standard for prosthetic funding in 2004,8 and australia initiated the https://doi.org/10.33137/cpoj.v4i2.35972 7 petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 issn: 2561-987x (in) access to artificial limbs: the patient’s perspective petlock & dimario, 2021 cpoj special s p e c ia l i s s u e process of implementing a national standard in 2019.9 as for england, an executive body was created in 2012, nhs england.10 although nhs england provides a national standard for prosthetic funding,11 such a standard may have been prior present to its establishment in 2012. though a provincial power, the canada health act sets the national standard for physician services provided in hospitals. assistive devices are seldom provided in hospital by a physician. prostheses are prescribed by a physician, but dispensed by prosthetists inside a hospital or outside, in a privately run certified clinic. hence, the provinces may execute discretion on the level of support they decide to provide. sadly, as we summarized above, provincial funding contributions fall short of the actual cost across the country, with some provinces containing no funding at all. while constitutionally a provincial power, it is not unfamiliar for the federal government to set national standards in areas of provincial jurisdiction, especially as it relates to health care. in fact, it has largely been regarded as a critical role of the federal government in canada to set these standards to ensure that canadian values are upheld. this obligation is set out in the constitution and is affirmed each time the federal government becomes a signatory to a united nations declaration. the responsibility and the obligation are clear: the federal government must ensure that national standards are set and upheld, especially in areas affecting vulnerable people such as those with disabilities, including persons with amputations. it is an accessibility issue and an issue of national importance. we feel that the federal government has the responsibility and the obligation to be proactive in setting national standards, especially if these national standards affect vulnerable minority groups and groups protected under the canadian human rights act and are connected to commitments made on the international stage. build legislation to prevent insurers from being able to create and sell insurance policies that have arbitrary caps on prosthetic funding due to the serious lack of adequate funding for assistive technology at the provincial healthcare level, many persons with disabilities, especially amputees, rely heavily on their extended benefits or private insurance to help to ensure that the assistive devices they require are affordable. sadly, too many of these insurance and extended benefits packages contain arbitrary limits on contributions for essential medical devices, including artificial limbs. the insurance industry in canada is, in this way, underregulated. we need legislation, similar to the statutory accident benefits schedule for motor vehicle insurance, which sets out base limits on what insurance companies must cover for artificial limbs. the war amps successfully persuades insurers at the grassroots level, case by case, and through higher level negotiations and educational strategy to demonstrate that it is in their best interest to appropriately cover the cost of prosthetic care. sadly, without the strong arm of legislation, we do not feel that sufficient and widespread change will occur. accessibility legislation across the country, at the federal and provincial level, sweeping progress has been made to enact comprehensive accessibility legislation. the definition of accessibility has expanded in recent years from a narrow view focusing on ramps and elevators to digital access and universal design. in order for accessibility legislation in canada to truly meet its objectives, the legislation must guarantee the availability of appropriate coverage for artificial limbs for all canadians who require it. assistive technology, including prosthetic care, is a critical element of accessibility for amputees. without these tools, persons with disabilities are barred from completing their activities of daily living, as well as accessing communities and workplaces. the disability community needs a standard which facilitates affordable access to assistive devices, as without this, accessibility will not be achieved. we believe that, through accessibility legislation, both federal and provincial governments have the major responsibility to set and uphold an appropriate standard for artificial limbs, as per their commitment to accessibility, the united nations and all canadians. discussion federal and provincial funding agencies, as well as private insurers provide insufficient funding for prosthetic care. their prosthetic funding policies are missing the mark and failing to address the reality of living with amputation. each province and territory have their own regime, failing in their own unique way to adequately respond to the reality of living with amputation and relying on prosthetic care. in turn, we see vast diversity of insurance policy frameworks pertaining to artificial limbs which perniciously miss the mark, leaving the amputee without the insurance coverage they thought they had paid for. after the traumatic loss of a limb, if an amputee cannot afford to purchase their prosthesis, they are re-victimized, as navigating the repeated red tape, denials and confusion of the process can re-trigger the trauma and direct focus to the loss. attitudinal barriers and missed legislative opportunities compound the issue. both the canadian public and key stakeholders including insurers, and government agents exhibit a lack of understanding of a very complex area of health care and medicine, chronically underestimate the cost of prosthetic technology and exhibit sci fi syndrome, which all lead decision-makers to build policies that are not reflective of the reality of living with amputation. https://doi.org/10.33137/cpoj.v4i2.35972 8 petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 issn: 2561-987x (in) access to artificial limbs: the patient’s perspective petlock & dimario, 2021 cpoj special s p e c ia l i s s u e current legislative frameworks that could ensure access to funding for prosthetic care are underutilized, including the united nations convention on the rights of persons with disabilities, which sets out that state parties must take steps to facilitate access to affordable prosthetic care. the enforcement mechanism of this convention can be leveraged after all canadian remedies have been exhausted. the federal government has also failed to set a national standard for appropriate prosthetic funding at the provincial level, enact legislation to prevent insurers from being able to create and sell insurance policies that have arbitrary caps on prosthetic funding, and include considerations for access to funding for assistive devices into accessibility legislation. as such, they are allowing canada to lag significantly behind other comparable countries. they are allowing vulnerable persons with amputations to be unprotected by high level legal mechanisms. hence, holding funding agencies accountable and advocating on behalf of amputees is important in this regard. conclusion recent years have demonstrated that prosthetic funding provided by public and private funding agents fails to meet the needs of amputees, creating a large barrier to access to care. both the war amps and medical professionals are committed to collaborating to respond to the urgent, complex and multi-faceted issue of insufficient prosthetic funding in canada. medical professionals can assist further by enrolling all amputees with the war amps child or adult amputee programs, challenging issues with insufficient prosthetic funding, and continuing to initiate discussion to educate other medical professionals, the public and the patient population about the issue to generate and leverage the “shock” in response to the serious inadequacies with prosthetic funding in this country. the issues with access to prosthetic funding are significant, complex, and not well known or understood. as the voice representing the needs of all amputees in canada, the war amps is committed to crusading for reform on this issue. with a collaborative and multi-faceted approach, we can continue to move the ball forward to remedy this significant gap. persons with amputation have experienced significant trauma. a small and vulnerable, yet often resilient demographic, persons who have lost limbs deserve access to prosthetic care. access to appropriate prosthetic coverage will help restore some of what they lost with the loss of their limbs, without the fear, anxiety and veritable humiliation that accompanies insufficient funding for prosthetic care. advocacy for amputees: a call to action due to the limitations of the funding regimes available to canadian amputees, action is required to improve funding regimes for artificial limbs, and subsequently the lives of all amputees. since 2013, the war amps has been proactively extending support and sharing expertise with the government and insurers, as well as employers, and works with the profession to improve the standards of funding for artificial limbs through a crusade for reform. by educating public health care and private insurance agencies on the necessity of artificial limbs, the goal is to reform and improve the system so that amputees will be able to receive the limbs they need for their independence, safety, and security. collaboration between prosthetists, physiatrists, amputees, and charitable organizations will help with the identification of systemic issues in relation to inadequate prosthetic funding in an effort to improve funding for artificial limbs in canada. key steps that patients and professionals can take to contribute include: 1) enrolling all amputees with the war amps child or adult amputee programs one barrier to improving prosthetic funding is the lack of data and statistics regarding the number of amputees in canada. statistics canada and other agencies do not collect this information. hence, by enrolling all amputees, we can help address this knowledge gap by ensuring that data we collect on amputees is as representative as possible as a basis for argument and decision-making in support of prosthetic funding. 2) challenge inadequacies if medical professionals, in practice, encounter an issue with funding, whether government or insurance, we encourage them to take steps to challenge it. across the country, prosthetists have built this step into the support they offer to their patients with demonstrated success, but we understand the administrative burden this can present to a small business. hence, the war amps is available to assist with challenging these issues. we can appeal individual denials, or partial approvals. we can educate insurers, and provincial funding agencies on their inadequacies. we have successfully persuaded a number of funding agencies to apply appropriate funding on appeal through the use of alternative dispute resolution mechanisms (i.e., the submission of letters and appeals to the insurer), and we simply will not relent until we receive adequate response. in this way, we will continue to exert the required pressure toward change, and when the time is right, use these efforts as evidence towards the need for us to take the next step: to bring this issue into the international arena by way of the united nations convention of the rights of persons with disabilities. 3) educate and initiate medical professionals can continue to keep the war amps abreast of issues they are facing and call on the war amps https://doi.org/10.33137/cpoj.v4i2.35972 9 petlock a, dimario k. (in) access to artificial limbs: the patient’s perspective according to the war amps of canada. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.13. https://doi.org/10.33137/cpoj.v4i2.35972 issn: 2561-987x (in) access to artificial limbs: the patient’s perspective petlock & dimario, 2021 cpoj special s p e c ia l i s s u e for support to help strengthen the overall position and argument in favour of increased prosthetic funding. conversations must be initiated between contacts, acquaintances and other medical professionals who work with amputees to educate them on the issue. most canadians are unaware of the serious issues with prosthetic funding and, hence assume that appropriate funding is granted to all canadians. generating and leveraging this “shock” will help elevate the war amps’ crusade in the minds of the canadian public and thus, government agencies. the three actions listed above are first steps in this major crusade and may seem minor, but they play keystone roles in improving funding in canada. acknowledgements none. declaration of conflicting interests the authors declare no conflict of interest. sources of support none. references 1.sachgau o. the price of being pain free: why are life-changing biologics out of reach for so many? the globe and mail [internet]. 2015; [cited 2021 march 16]. available from: https://www.theglobeandmail.com/life/health-andfitness/health/the-price-of-being-pain-free-why-are-biologics-outof-reach-for-so-many/article26332629/ 2.medical advisory secretariat. total knee replacement: an evidence-based analysis [internet]. 2005; [cited 2021 march 11]. available from: https://oculuo.primo.exlibrisgroup.com/permalink/01ocul_uo/1lm0b9c/alma 991044822141705161 3.nhs england. clinical commissioning policy: microprocessor controlled prosthetic knees [internet]. 2016; [cited 2021 march 11]. available from: https://www.england.nhs.uk/wpcontent/uploads/2016/12/clin-comm-pol-16061p.pdf 4.un general assembly. convention on the rights of persons with disabilities: resolution / adopted by the general assembly [internet]. 2007; [cited 2021 jan 4]. available from: https://www.un.org/development/desa/disabilities/convention-onthe-rights-of-persons-with-disabilities/article-20-personalmobility.html 5.un general assembly. convention on the rights of persons with disabilities: resolution / adopted by the general assembly [internet]. 2007; [cited 2021 jan 4]. available from: https://www.un.org/development/desa/disabilities/convention-onthe-rights-of-persons-with-disabilities/article-32-internationalcooperation.html 6.canada accedes to the optional protocol to the unites nations convention on the rights of persons with disabilities [internet]. employment and social development canada. 2018; [cited 2021 jan 4]. available from: https://www.newswire.ca/newsreleases/canada-accedes-to-the-optional-protocol-to-the-unitednations-convention-on-the-rights-of-persons-with-disabilities701804101.html#:~:text=accession%20to%20the%20optional%2 0protocol,the%20convention%20have%20been%20violated. 7.united nation human rights office of the high commissioner. human rights bodies – complaints procedures [internet]. 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[cited 2021 march 17]. available from: https://www.england.nhs.uk/commissioning/spec-services/npccrg/group-d/d01/ authors scientific biography annelise petlock is a lawyer with an mba who serves as the manager of the war amputations of canada’s advocacy program. annelise has an in-depth understanding of amputation and the whole-body impact it has on the lives of individuals living with amputation, including the role of the artificial limb. the war amps is a charity devoted to improving the lives of amputees in canada, including children. the war amps provides financial assistance for artificial limbs, peer support and information on all aspects of living with amputation. keana dimario serves as a case coordinator of the war amputations of canada’s advocacy program. keana addresses issues facing amputees across all areas including insufficient prosthetic funding. https://doi.org/10.33137/cpoj.v4i2.35972 https://www.theglobeandmail.com/life/health-and-fitness/health/the-price-of-being-pain-free-why-are-biologics-out-of-reach-for-so-many/article26332629/ https://www.theglobeandmail.com/life/health-and-fitness/health/the-price-of-being-pain-free-why-are-biologics-out-of-reach-for-so-many/article26332629/ https://www.theglobeandmail.com/life/health-and-fitness/health/the-price-of-being-pain-free-why-are-biologics-out-of-reach-for-so-many/article26332629/ https://ocul-uo.primo.exlibrisgroup.com/permalink/01ocul_uo/1lm0b9c/alma991044822141705161 https://ocul-uo.primo.exlibrisgroup.com/permalink/01ocul_uo/1lm0b9c/alma991044822141705161 https://ocul-uo.primo.exlibrisgroup.com/permalink/01ocul_uo/1lm0b9c/alma991044822141705161 https://www.england.nhs.uk/wp-content/uploads/2016/12/clin-comm-pol-16061p.pdf https://www.england.nhs.uk/wp-content/uploads/2016/12/clin-comm-pol-16061p.pdf https://www.un.org/development/desa/disabilities/convention-on-the-rights-of-persons-with-disabilities/article-20-personal-mobility.html https://www.un.org/development/desa/disabilities/convention-on-the-rights-of-persons-with-disabilities/article-20-personal-mobility.html https://www.un.org/development/desa/disabilities/convention-on-the-rights-of-persons-with-disabilities/article-20-personal-mobility.html https://www.un.org/development/desa/disabilities/convention-on-the-rights-of-persons-with-disabilities/article-32-international-cooperation.html https://www.un.org/development/desa/disabilities/convention-on-the-rights-of-persons-with-disabilities/article-32-international-cooperation.html https://www.un.org/development/desa/disabilities/convention-on-the-rights-of-persons-with-disabilities/article-32-international-cooperation.html 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https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 2 2024 professional opinion ratto m, southwick d. prosthetist knowledge and 3d printing. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.5. https://doi.org/10.33137/cpoj.v7i2.42175 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i2.42175 1 ratto m, southwick d. prosthetist knowledge and 3d printing. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.5. https://doi.org/10.33137/cpoj.v7i2.42175 professional opinion prosthetist knowledge and 3d printing ratto m1*, southwick d2 1. faculty of information, university of toronto, toronto, canada. 2. autodesk inc., san francisco, california, usa. introduction in this paper we briefly explored 3d printing and prosthetics, understanding 3d printing as connected to but distinct from the long history of cad/cam technologies in p&o. work on digital production of prosthetics began in the 1960’s but despite the development of multiple systems over the last 70 years, most prosthetic devices are still produced through craft processes. if asked, most prosthetists will note the existence of automated systems, but highlight their inadequacies in coming to terms with the complex topologies and textures of a humans and their cost and difficulty of use. recent technological developments, including lower cost 3d scanners with higher accuracies and easier to use 3d printers capable of printing in higher tensile strength materials offer the possibility of overcoming these stated challenges. however, developing digital prosthetic toolchains that properly acknowledge and instantiate forms of knowledge that constitutes prosthetist expertise is a longstanding challenge in the development of novel cad/cam prosthetic systems. 3d printing and prosthetics in 1990, a research group at northwestern university, in conjunction with baxter healthcare, made a single transtibial (tt) socket using a form of 3d printing known as stereolithography (sla).1 shortly thereafter, the university of texas at austin and the university of health science centre at san antonio began experimenting with selective laser sintering (sls), which led to an amputee briefly wearing a 3d printed socket in a controlled clinical setting in 1992.2 while quite limited in scope, these early studies in the application of 3d printing within the p&o profession had a large impact in the profession. in the conclusion of the 1992 report written by the department of veteran affairs (va) on the automated fabrication of mobility aids (afma), which was discussed in detail in the previous chapters, six areas of research concentration are suggested. of these six, one specifically called for further research into methods for “automating the prosthesis manufacturing process”, and the eventual direct prosthesis manufacturing from cad files through “rapid prototyping cam technologies”.3 the reasoning behind this move was that “rapid prototyping cam technologies”, or 3d printing, seemingly allowed for the manufacturing of prosthetic devices without the interruptive craft methods used in the traditional methods during the fabrication of the device. a new kind of study into the application of 3d printing in p&o work emerged in the late 2000s, which differed from earlier studies in that they were a direct response by the p&o community to developments in technology and to new non-expert actors in the field. the introduction of the makerbot cupcake cnc and the thing-o-matic, in 2009 and 2010 respectively, marked an important turning point in the development of 3d printing technology from both a cost and usability perspective.4 under such slogans as “if you can think it, you can make it” makerbot began to actively * corresponding author: matt ratto, phd faculty of information, university of toronto, toronto, canada. e-mail: matt.ratto@utoronto.ca orcid id: https://orcid.org/0000-0002-3554-4513 open access abstract in this paper we briefly explored the history of 3d printing in prosthetics. we provided details of our own work developing 3d printing design tools from 20142020 noting how claims around prosthetist experience and knowledge have been supported and/or questioned in the development of new device production techniques. we ended by arguing for deeper attention to prosthetist knowledge and experience in the design of the growing 3d printing ecosystem, seeing this focus as necessary and important to preserve and support clinical prosthetist in the production of well-fitting and appropriate devices for patients. citation ratto m, southwick d. prosthetist knowledge and 3d printing. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.5. https://doi.org/10.33137/cpoj.v7i2.42175 keywords prosthetics, orthotics, fabrication, additive manufacturing, 3d printing, design, automation, knowledge, prosthetist, orthotist journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 2, article no.5. 2024 https://doi.org/10.33137/cpoj.v7i2.42175 https://orcid.org/0000-0002-3554-4513 https://doi.org/10.33137/cpoj.v7i2.42175 https://jps.library.utoronto.ca/index.php/cpoj/index 2 ratto m, southwick d. prosthetist knowledge and 3d printing. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.5. https://doi.org/10.33137/cpoj.v7i2.42175 prosthetist knowledge and 3d printing ratto m, & southwick d, 2024 canadian prosthetics & orthotics journal issn: 2561-987x promote the concept that “desktop manufacturing” was leading to a future of de-centralized production. this led to various hardware and software developments that not only further reduced the costs of 3d printing, but also made the technology far more accessible to users without backgrounds in engineering. these cheaper and more accessible 3d printers created by companies like makerbot effectively addressed the major issue of cost associated with the technology. yet, in doing so, a new type of problem was introduced in the form of non-expert actors developing digital tools and prosthetics. in the late-2000s various organizations with little to no connection to the p&o profession began to use 3d printers to provide cheap and easily accessible prosthetics for both the developed and developing world by allowing users to fabricate their own devices.5 these desktop printable prosthetic devices were mainly upper extremity prostheses such as body-powered “hands” such as the raptor hand developed by project e-nable.6 the p&o profession responded to these devices by studying them in various contexts. while acknowledging that these devices were useful for training patients to wear devices, on a functional level they were severely lacking. the durability of these prosthetics devices also proved problematic, with joints and areas of pressure frequently breaking.7,8 finally, and most importantly from the perspective of the p&o profession, was the fit of these devices. most of these devices used simple measurements to scale 3d printed components. the raptor hand, for example, is a device that uses three measurements on the wrist and the palm to determine the size of the prosthetic device. in their critiques of this approach the p&o community note that this not only limits the “kinds” of amputations these devices can be used for, but it also fails to properly transfer the biomechanical forces that act on the limb.7,8 while the overall assessment of diy prosthetics within the p&o community is fairly negative, those who have examined these devices often acknowledge the potential of 3d printing technology for the profession. thus, the challenge going forward is to develop a system that better understands the various nuances of the p&o profession, while also leveraging the potential benefits of these technologies. this, in of itself, is a substantial undertaking. what has made this task even harder is the popular perception of 3d printing and prosthetics as a “solved problem” that formed due to the extensive media coverage of diy prosthetics organizations.9 unfortunately, this popular perception often involves a reduced role for prosthetist expertise in a 3d printed future in no small part due to a lack of understanding of the clinical and material nature of prosthetics themselves. 3d printability since 2014, the authors of this paper have been part of a project called ‘3d printability’, developing 3d design and printing tools for use in rehabilitation clinics in low to middle income countries in sub-saharan africa and southeast asia. supported initially by a charitable organization and later through award-based funders including grand challenges canada, autodesk foundation, and a google impact award, the team has created and deployed multiple versions of a software and hardware toolchain to produce pediatric lower-limb prosthetic and orthotic devices. more than 20 prosthetists and prosthetic technicians have participated in design exercises and been trained in 3d scanning, design, and printing technologies. clinics that have partnered in this work include comprehensive rehabilitation services for people with disability in uganda (corsu) hospital, comprehensive community based rehabilitation tanzania (ccbrt) and tanzania training centre for orthopaedic technologists (tatcot), and the cambodian school of prosthetics and orthotics (cspo) (figure 1). figure 1: images of patients from uganda and tanzania, 2018. nia technologies (http://www.niatech.org), a non-profit organization located in toronto, canada currently provides support and continues to improve software and hardware solutions for p&o. three clinical trials were carried out https://doi.org/10.33137/cpoj.v7i2.42175 http://www.niatech.org/ 3 ratto m, southwick d. prosthetist knowledge and 3d printing. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.5. https://doi.org/10.33137/cpoj.v7i2.42175 prosthetist knowledge and 3d printing ratto m, & southwick d, 2024 canadian prosthetics & orthotics journal issn: 2561-987x during the project, an initial trial at corsu in uganda, followed by a multi-site trial that included each of the partner sites described above. a third and smaller trial was also conducted in canada at st. john’s rehabilitation clinic/sunnybrook hospital in toronto. a more detailed description and accounting of this work can be found in our previous publications.10-13 this paper will focus only on the 3d design software developed during the project. the goal of 3d printability was to extend the traditional fabrication and fitting processes for lower-limb prosthetic sockets with 3d design software and hardware. as is wellknown to the readers of this journal, the traditional socket fabrication and fitting process involves a three-step process. in the first step a “negative model” of the residual limb in created using plaster wraps. next, a positive model is created by pouring plaster material into the negative model, allowing it to harden, and removing the wraps. this positive model is then “rectified”, a process where prosthetists add and subtract material to create a shape that, when used to produce a socket, will properly distribute weight and pressure across the residual limb. in the final step, a socket is fabricated over the positive model, using thermoplastics or lamination processes. finally, the socket is fitted to the patient after some light post-production, such as sanding rough edges. during the actual fitting process, minor modifications can be made to the socket based on feedback from the patient. if, however, major modifications are required, the entire process must begin again. similarly, when a patient requires a new socket, the entire process begins again. 3d printability was developed to reduce the time to completion of a prosthetic socket and by doing so to increase the number of patients that could be treated by rehabilitation clinics in low resource areas. this goal has many similarities to the reasons for the original development of digital fabrication technologies for p&o which included a strong desire to better capture the skills and expertise used in the development of prosthetic sockets.14-17 3d printability and “socket mixer” in 2014, after initial experiments in 3d scanning, design, and printing (figure 2), interviews with prosthetists and prosthetic users in canada and uganda, the 3d printability team began work on 3d design software made to supplement an existing cad/cam solution called canfit, made by vorum inc.18 while canfit could be used to modify 3d scans and produce subtractive cnc milling patterns to produce positive models, at that time no prosthetist-specific software programs existed that could produce 3d printable prosthetic sockets. the first version of this software we called ‘socketmixer’. it worked as an add-on to the popular autodesk meshmixer free 3d software package19 and created an additional menu panel with custom commands focused on socket production. (figure 3) our goal with this software was to simplify the complex chain of commands that could be used by a skilled engineer to convert a digital scan to a socket. however, this solution did not involve an automatic conversion from digital data to 3d printable socket, but instead allowed prosthetists to make key decisions about the resulting socket, including supporting the manipulation of the model to expand or reduce specific areas, control the thickness of the socket and the shape of the brim, and the location and shape of the mounting point for attaching the socket to the rest of the prosthetic device. our goal in creating this simple software was to reduce complexity of use while still allowing the prosthetists own style and knowledge to be utilized. figure 2: author being scanned and printed socket (top and middle); canfit software (bottom). https://doi.org/10.33137/cpoj.v7i2.42175 4 ratto m, southwick d. prosthetist knowledge and 3d printing. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.5. https://doi.org/10.33137/cpoj.v7i2.42175 prosthetist knowledge and 3d printing ratto m, & southwick d, 2024 canadian prosthetics & orthotics journal issn: 2561-987x niafit and prosthetist knowledge our initial work with canfit and on socketmixer demonstrated the potential of 3d printing for 3d printing prosthetic sockets. it also revealed the difficulty for prosthetists to use multiple software programs to produce a socket. in our initial solution, prosthetists needed to start with from one program for scanning, move the resulting file to a different program for scan cleanup, still another for modeling, and yet another for the actual preparation of a printable file. this complexity created many opportunities for error and required prosthetists to learn major new skills to produce good sockets. to solve this issue, we decided to produce a more integrated software solution in which a single program provided all capabilities. extended development, many tests and design research with prosthetists, and multiple years of testing resulting in niafit, a scanning, modeling, and printing suite. figure 3: socketmixer, nia technologies, 2014. as is shown in figure 4, the user flow was separated into three main screens. first, a scan taken using an ipad + structure scanner (occipital inc.) was imported into niafit. the initial interface focused on tools needed for reducing the complexity of the scan and preparing the file for modeling activity. clicking with a mouse on one area of the scan selects it (highlighted in orange in figure 4) and the forward and back arrow keys extend the scan to contiguous areas. when done, all unselected parts of the scan are removed, and the resulting 3d shape is realigned within the view window. at this point, modeling tools become available, that allow focused and overall smoothing, as well as the building up or reducing of regions on the model. other functions are also available, such as the creation of trimlines and the taking of measurements. when ready, the user moves to the final stage of the process. here, tools are available that reproduce the process of ‘draping’ thermoplastics to produce a socket. in developing niafit, three concerns were paramount. first, as noted above, we wanted to create a single application to reduce the complexity of the digital socket development process. second, we chose to structure the digital user experience to reproduce as much as possible the traditional process of prosthetic socket production. by designing the experience in this way, the goal was to reduce the retraining necessary for prosthetists to transition to a digital workflow and to conserve their current knowledge and ways of working. third, we wanted to help prosthetists extend and communicate their knowledge. a key insight by early developers of cad/cam systems in prosthetists was that such systems could make prosthetist skill and expertise more visible and reproduceable than the destructive craftbased processes then – and still – in use.16 in niafit, all prosthetist operations are preserved as separate digital ‘moves’, allowing for users to move back and forth within the prosthetic socket production process. importantly, such ‘moves’ allow both the sequential ‘undo’ and ‘redo’ that is typical of digital workflows, but also the ability to remove or rework operations out of sequence, with the topology of the positive model or digital socket adjusting automatically. such processes allow novel forms of ‘branching’ in prosthetic design and also foster and support the future development of more collaborative forms of prosthetic design and production. we developed this functionality based on our ongoing collaboration with working prosthetists who sought these new capabilities. only recently have more mainstream cad/cam design tools begun to incorporate similar branching20 and collaboration21 features. call to action despite over 70 years of work on cad/cam and over 30 years since the first 3d printed prosthetic socket, these technologies remain undeveloped and of limited current use in mainstream p&o. new technical developments, including inexpensive scanners and printers capable of higher resolutions and stronger materials, are now available, and these may increase adoption. however, we strongly believe that design software needs to be developed in ways that foster, support, and extend prosthetist knowledge and expertise. this is best done with the participation of prosthetists’ themselves who should drive the creation of new systems and platforms to best serve their patients. https://doi.org/10.33137/cpoj.v7i2.42175 5 ratto m, southwick d. prosthetist knowledge and 3d printing. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.5. https://doi.org/10.33137/cpoj.v7i2.42175 prosthetist knowledge and 3d printing ratto m, & southwick d, 2024 canadian prosthetics & orthotics journal issn: 2561-987x figure 4: three main screens and functions in niafit, 2018. acknowledgements the work briefly surveyed in this article required the contribution of time and energy from prosthetists and other experts in canada and at the many sites when these technologies were trialled. we would particularly like to thank moses kaweesa, jennan taremwa, thearith heang, sisary kheng, odom teap, donald mchihiyo, ruth onesmo, baraka moshi, violet mwaijande for their knowledge and prosthetic expertise, and jerry evans, joshua qua hiansen, and howie k. safeer from nia technologies. gordon ruder, dan blocka, and sandra ramdial provided important perspectives throughout the project. in memory of diane johnson. her generosity and kindness will not be forgotten. declaration of conflicting interests the lead author was the chief scientist of nia technologies, the non-profit formed to continue development of 3d design software from 2015-2020 and received compensation in this role. he served as the pi on all grants associated with its development. authors contribution both authors contributed equally to the research and the writing of this manuscript. sources of support this work was supported under the 3d printability project funded by the inclusive design institute; 2011 canada foundation for innovation; 2014 canada grand challenges stars in global health; 2016 canada grand challenges transition to scale; 2016 google impact award; 2016 mitacs award. references 1.rovick js, chan rb, van vorhis r, childress d. computer-aided manufacturing in prosthetics: various possibilities using industrial equipment. in: proceedings of the 7th world congress of the international society for prosthetics and orthotics. 1992;28:22. 2.rogers we, crawford rh, beaman jj, walsh ne. fabrication of prosthetic socket by selective laser sintering. in: international solid freeform fabrication symposium. 1991. 3.houston vl, burgess em, childress ds, lehneis hr, mason cp, garbarini ma, et al. automated fabrication of mobility aids (afma): below-knee casd/cam testing and evaluation program results. j rehabil res dev. 1992;29(4):78-124. doi: 10.1682/jrrd.1992.10. 0078 4.lipson h, kurman m. fabricated: the new world of 3d printing. john wiley & sons; 2013. 5.burn mb, ta a, gogola gr. three-dimensional printing of prosthetic hands for children. j hand surg. 2016;41(5):e103-e109. doi: 10.1016/j.jhsa.2016.02.008 6.ten kate j, smit g, breedveld p. 3d-printed upper limb prostheses: a review. disabil rehabil assist technol. 2017;12(3):300-314. doi: 10.1080/17483107.2016.1253117 7.diment le, thompson ms, bergmann jh. three-dimensional printed upper-limb prostheses lack randomised controlled trials: a systematic review. prosthet orthot int. 2018;42(1):7-13. doi: 10.1177/0309364617704803 8.zuniga jm, peck j, srivastava r, katsavelis d, carson a. an open source 3d-printed transitional hand prosthesis for children. j prosthet orthot. 2016;28(3):103-108. doi: 10.1097/jpo. 0000000000000097 9.birrell i. 3d-printed prosthetic limbs: the next 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10.3109/03093648909079405 16.saunders cg, foort j, bannon m, lean d, panych l. computer aided design of prosthetic sockets for below-knee amputees. prosthet orthot int. 1985;9(1):17-22. doi: 10.3109/03093648509164819 17.wilson ab. limb prosthetics. 6th ed. new york, n.y: demos; 1989. 18.canfit orthotics and prosthetics cad [internet]. vorum inc., canada [cited 2023, aug 23]. available from: https://vorum.com/canfit-op-cad-software/ 19.autodesk meshmixer [internet]. autodesk inc., usa [cited 2023, aug 23]. available from: https://meshmixer.com/ 20.cheng k, cuvin p, olechowski a, zhou s. user perspectives on branching in computer-aided design. in: the 26th acm conference on computer-supported cooperative work and social computing (cscw). 2023. 21.cheng k, zhou s, olechowski a. in the age of collaboration, the computer-aided design ecosystem is behind: evidence from an interview study of distributed cad practice. in: the 26th acm conference on computer-supported cooperative work and social computing (cscw). 2023. authors scientific biography matt ratto is professor and associate dean, research in the faculty of information at the university of toronto. he studies and practices ‘critical making’, work that combines humanities insights and engineering practices and has published extensively on this concept. he publishes across a wide range of disciplines including recent work on hope and interventional digital projects (acm cscw 2023), generative ai and mental health (jmir 2023), and additive manufacturing and prosthetics (cjpo 2021; jpo 2021). daniel southwick is a senior ux researcher at autodesk, inc. his work focuses on the use of cad/cam tools in manufacturing and the development of new ai-based systems. he received his phd in 2019 from the university of toronto. his thesis, “expertise in the age of digital fabrication,” explored the history of design and manufacturing with a special focus on digital fabrication of prosthetic devices. https://doi.org/10.33137/cpoj.v7i2.42175 https://vorum.com/canfit-op-cad-software/ https://meshmixer.com/ all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 research article resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.37873 1 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 research article a psychosocial adjustment measure for persons with upper limb amputation resnik l.j. 1,2*, ni p. 3, borgia m.l. 1, clark m.a. 2,4 1 research department, providence va medical center, providence, usa. 2 department of health services, policy and practice, brown university, providence, usa. 3 biostatistics and epidemiology data analytics center (bedac), boston university school of public health, boston, usa. 4 department of population and quantitative health sciences, university of massachusetts medical school, massachusetts, usa. introduction individuals experiencing limb loss undergo social and psychological adjustment as well as physical adjustment.1-4 psychosocial adjustment is a process that may involve changes in body image, personal identity, lifestyle and daily functioning.5 psychosocial adjustment can be affected by clinical conditions. a substantial proportion of persons with upper limb amputation experience clinical depression (2055%),1,6,7 post-traumatic stress disorder (23–24%),1,6 anxiety (36%),5 and long term post-traumatic psychological distress (25%) after amputation.8 more than 20% have other co-occurring conditions.6 levels of depression and anxiety are greater and psychosocial adjustment poorer in persons with upper limb amputation (ula) as compared to those with lower limb amputation,9 perhaps due to the visibility of the upper limb and difficulty covering a prosthesis under clothing. persons with upper limb amputation report an ongoing awareness of difference in appearance,10 as well open access volume 5, issue 1, article no.8. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: measurement of psychosocial adjustment after upper limb amputation (ula) could be helpful in identifying persons who may benefit from interventions, such as psychotherapy and/or support groups. however, available measures of psychosocial adjustment after limb loss are currently designed for prosthetic users only. objective: to create a measure of psychosocial adjustment for persons with ula that could be completed by individuals regardless of whether a prosthesis is use. methodology: we modified items from an existing trinity amputation and prosthesis experience survey (tapes) measure and generated new items pertinent to persons who did not use a prosthesis. item content was refined through cognitive interviewing and pilot testing. a telephone survey of 727 persons with major ula (63.6% male, mean age of 54.4) was conducted after pilot-testing. after exploratory and confirmatory factor analyses (efa and cfa), rasch analyses were used to evaluate response categories, item fit and differential item functioning (dif). item-person maps, score distributions, and person and item reliability were examined. test-retest reliability was evaluated in a 50-person subsample. findings: efa and cfa indicated a two-factor solution. rasch analyses resulted in a 7-item adjustment to limitation subscale (cfi=0.96, tli=0.95, rmsea=0.128) and a 9-item work and independence subscale (cfi=0.935, tli=0.913, rmsea=0.193). cronbach alpha and icc were 0.82 and 0.63 for the adjustment to limitation subscale and 0.90 and 0.80 for the work and independence subscale, respectively. conclusions: this study developed the psychosocial adjustment to amputation measure, which contains two subscales: 1) adjustment to limitation and 2) work and independence. the measure has sound structural validity, good person and item reliability, and moderate to good test-retest reliability. article info received: december 17, 2021 accepted: march 10, 2022 published: april 5, 2022 citation resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8.https://doi.org/10.33137/cpoj. v5i1.37873 keywords upper limb amputation, upper limb prosthesis, psychosocial adjustment, factor analysis, rasch analysis, psychometrics, prosthesis * corresponding author linda j. resnik pt, phd research department, providence va medical center, 830 chalkstone ave, building 32, providence, ri 02908 e-mail: linda.resnik@va.gov orcid id: https://orcid.org/0000-0002-0168-6759 https://doi.org/10.33137/cpoj.v5i1.37873 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i1.37873 https://doi.org/10.33137/cpoj.v5i1.37873 mailto:linda.resnik@va.gov https://orcid.org/0000-0002-0168-6759 2 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj as high levels of body image anxiety and social insecurity that may impact their relationships.11 coping strategies, social support, social discomfort, perceived social stigma, and self-consciousness in public are associated with adjustment to amputation.5,12 while several earlier studies utilized qualitative methods to understand psychosocial adjustment after limb loss,10,11,13-15 few studies have used quantitative measures of psychosocial adjustment. studies that did use quantitative measures have been limited to prosthesis users.5,9,16,17 measurement of psychosocial adjustment could be helpful in identifying persons who might benefit from interventions such as psychotherapy and/or support groups. further, repeated measures of psychosocial adjustment may be needed to understand the experiences and needs of persons with limb loss, given that that adjustment to limb loss is a process that occurs over time.13 unfortunately, to date, there are no measures of psychosocial adjustment that can be used by all persons with ula. while measures such as the psychosocial adjustment scale of the trinity amputation and prosthesis experience survey (tapes) exist, this measure specifically targets psychosocial adaptation to prosthesis use. the majority of items in this scale refer to use of “an artificial limb”, making it inappropriate for persons with amputation who do not use a prosthesis. given the prevalence of prosthesis abandonment in ula (estimated to be between 20-40%),18,19 a measure that can be completed by prosthetic users as well as non-users is needed. thus, the purpose of this study was to create a measure of psychosocial adjustment for persons with ula that could be completed by individuals regardless of prosthesis use. methodology we modified items from the tapes measure, identified new items, and refined this new item set through cognitive testing and pilot testing. the original tapes instrument is comprised of three sections (psychosocial adjustment, activity restriction, and satisfaction with prosthesis), each of which contains one or more individually scored subscales, with 15 items related to adjustment.20,21 while the tapes was originally developed for persons with lower limb amputation, the tapes-ula was suggested for use in persons with upper limb loss.22 the tapes-ula, eliminates the item, “i don’t care if anyone notices i am limping” due to lack of relevance for persons with upper limb loss. twelve of the 14 remaining tapes-ula items specifically mention the use of an artificial limb. we first made some changes to the original tapes-ula items. we changed terminology, replacing the word “amputation” with the words “limb difference”, to be more inclusive of persons with congenital limb difference. two items had similar content, “i don’t mind people asking me about my artificial limb, and i have difficulty in talking about my limb loss in conversation”, therefore we selected the item that could be completed regardless of prosthesis use. we then added 6 new items that could be completed by both users and non-users of prostheses. the new items were: “i have adjusted to being an amputee”, “i don’t care if somebody looks at my residual arm”, “my amputation interferes with the ability to do my work”, “having an amputation makes me more dependent on others than i would like to be”, “having an amputation limits the kind of work that i can do”, and “having an amputation limits the amount of work that i can do.” we then administered the item set in cognitive interviews and utilized the feedback to iteratively refine the items and instructions. cognitive interviewing is an approach commonly used to enhance validity of item content and response processes.23 cognitive interviews were conducted with 11 participants with ula (9 prosthesis users, 2 non-user). the sample was 63.6% male, with a mean age 54.4 years (table 1). during these interviews, participants were asked to think out loud as they answered the items and to identify any instructions or words that were confusing as well as any questions that were difficult to answer.24,25 table 1: characteristics of the cognitive testing and pilot study samples. cognitive, n=11 pilot, n=20 age, mean (sd) 54.4 (9.8) 61.9 (13.5) gender, n (%) male 7 (63.6) 11 (55.0) female 4 (36.4) 9 (45.0) amputation level, n (%) transradial/wrist disarticulation 5 (45.5) 11 (55.0) transhumeral/elbow disarticulation 6 (54.6) 5 (25.0) shoulder 0 (0.0) 4 (20.0) bilateral upper limb loss 1 (9.1) 4 (20.0) prosthesis user, n (%) 9 (81.8) 15 (75.0) primary prosthesis type, n (%) body powered 6 (66.7) 6 (40.0) myoelectric 2 (22.2) 6 (40.0) hybrid 0 (0.0) 1 (6.7) cosmetic 1 (11.1) 1 (6.7) sports/recreation 0 (0.0) 1 (6.7) etiology, n (%) combat injury 0 (0.0) 2 (10.0) accident 2 (27.3) 10 (50.0) burn 1 (9.1) 2 (10.0) cancer 1 (9.1) 1 (5.0) diabetes 0 (0.0) 0 (0.0) infection 1 (9.1) 2 (10.0) congenital 3 (27.3) 5 (25.0) other 2 (18.2) 2 (10.0) race, n (%) white 10 (90.9) 14 (77.8) black 1 (9.1) 1 (5.6) other 0 (0.0) 3 (16.7) https://doi.org/10.33137/cpoj.v5i1.37873 3 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj as a result of feedback obtained in the cognitive interviews, we replaced the word “residual limb” with the word “stump”, because some respondents in the cognitive interviews told us that this was the terminology that they used most often to refer to their residuum. we also replaced the term “artificial limb” with the term “prosthesis” because we found that was more commonly used in our sample. we tested the use of the terms “amputation”, “amputee”, and “limb difference.” because participants with congenital limb difference in our sample did not express any concerns about use of the term “amputation” in some items, we retained that language in new items. at the end of cognitive testing, we had a 19-item set. ten items were specific to prosthesis users, and 9 were pertinent to prosthesis users as well as non-users. next, we discussed the measure and instructions with the survey team, who provided feedback based on their prior experiences interviewing individuals with ula. as a result, we revised the instructions for bilateral participants who were prosthetic users, updating them to refer to the prostheses “on either side” instead of “on your dominant side.” we also changed the wording of the response options so that the middle of the scale was “neither disagree nor agree” (rather than “neither agree nor disagree”) to match the directionality of responses within the original psychosocial adjustment tapes scales. the refined itemset and instructions were then pilot tested in a convenience sample of 20 participants (5 non-users and 15 prosthesis users, 4 persons with bilateral limb loss, 55% male, mean age 61.9) (table 1). no revisions were made to the items or instructions after pilot testing. the final instrument, which was administered in a telephone survey to 727 participants, is shown in appendix a. a subgroup of 50 persons (the reliability sample) completed the telephone survey two times within one week. sample and recruitment participants were included if they had amputation at the level of the wrist or above and were able to understand study requirements and hear well enough to comprehend questions administered over the telephone. participants for all phases of the study (cognitive interviews, pilot testing and field testing) were recruited from several sources: an earlier study conducted in the department of veterans affairs (va), a list of veterans who had received va care between january 1, 2016 – june 1, 2019, eblasts sent from the amputation coalition of america, and recruitment letters sent from a private prosthetics care company. the study was approved by va central institutional review board, and all participants gave oral informed consent as approved by the irb. data analysis overview characteristics of the field study sample were described. to evaluate structural validity of the measure, we performed exploratory and confirmatory analyses using data from the first 351 persons (subsample 1) and final confirmatory analyses using data from the subsequent 376 respondents (subsample 2). we then used data from the entire sample to develop rasch partial credit models and evaluated item fit statistics, item category curves, and the presence of differential item functioning (dif). we also evaluated itemperson maps, score distributions, and person and item reliability. finally, we examined test-retest reliability using a convenience subgroup of 50 persons who completed the telephone survey two times within two weeks. these persons were selected based on amputation level and laterality to ensure representation across these key characteristics. factor analyses the dimensionality of the item pool was evaluated using exploratory factor analysis (efa) and confirmatory factor analysis (cfa). in the efa analysis, we utilized factor loadings, eigenvalues, and percentage of variance explained by the first factor to assess unidimensionality for the full 19-item measure. we determined the number of unidimensional factors by identifying the number of eigenvalues > 1 and applying parallel analysis.26 we assessed cfa model fit using the comparative fit index (cfi), tucker–lewis index (tli), root mean square error approximation (rmsea), and residual correlations. efa and cfa analyses were conducted with m-plus software.27 we considered cfi and tli values of 0.90 or higher and rmsea values <0.08 as acceptable model indices. after examining the model fit for all item combinations, we selected the optimal models that retained the most items with acceptable model fit. we evaluated local independence by inspecting the residual correlations between items; items with residual correlations greater than 0.2 were considered to have local dependence.28-30 we then performed cfa using data from subsample 2. fit criteria used in final confirmatory factor analyses were similar to those used in exploratory analyses. however, rather than using a stringent rmsea criteria, we focused on examining the residual correlations and eigenvalue ratios rather than on the rmsea value. we did this because rmsea is sensitive to the weight matrix, which is used in the chi-square calculation; a small change in the weight matrix (e.g. different samples) could cause large changes in rmsea. rasch partial credit modeling and dif evaluation rasch analyses involve probabilistic modeling of a latent trait, where persons and items are measured on the same interval scale; the rasch framework allows assessment of psychometric properties for the development and refinement of measures.31,32 rasch partial credit modeling of data from the entire sample was used to evaluate monotonicity, residual variance explained, item fit statistics, https://doi.org/10.33137/cpoj.v5i1.37873 https://www.va.gov/ https://www.va.gov/ https://www.amputee-coalition.org/ 4 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj table 2: characteristics of the field study sample. subsample 1 (n=351) subsample 2 (n=376) full sample (n=727) test-retest sample (n=50) agemean (sd) 64.0 (12.9) 58.7 (15.8) 61.2 (14.8) 61.1 (14.2) time since amputationmean (sd) 33.1 (18.4) 23.4 (19.7) 28.4 (19.6) 31.7 (19.7) status-n (%) veteran 334 (95.2) 216 (57.8) 550 (75.9) 47 (94.0) military 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) civilian 17 (4.8) 157 (42.0) 174 (24.0) 3 (6.0) unknown 0 (0.0) 1 (0.3) 1 (0.1) 0 (0.0) sex-n (%) female 10 (2.9) 142 (37.8) 152 (20.9) 2 (4.0) male 341 (97.2) 234 (62.2) 575 (79.1) 48 (96.0) race-n (%) white 284 (80.9) 313 (83.2) 597 (82.1) 40 (80.0) black 34 (9.7) 32 (8.5) 66 (9.1) 2 (4.0) unknown 20 (5.7) 19 (5.1) 39 (5.4) 6 (12.0) mixed 13 (3.7) 12 (3.2) 25 (3.4) 2 (4.0) amputation level-n (%) shoulder 42 (12.0) 33 (8.8) 75 (10.3) 10 (20.0) transhumeral 129 (36.8) 97 (25.8) 226 (31.1) 15 (30.0) transradial 180 (51.3) 203 (54.0) 383 (52.7) 15 (30.0) bilateral 0 (0.0) 43 (11.4) 43 (5.9) 10 (20.0) etiology-n (%) combat 102 (29.1) 55 (17.2) 157 (23.4) 16 (32.0) accident 237 (67.5) 204 (63.7) 441 (65.7) 31 (62.0) burn 34 (9.7) 35 (10.9) 69 (10.3) 9 (18.0) cancer 15 (4.3) 29 (9.1) 44 (6.6) 3 (6.0) diabetes 3 (0.9) 1 (0.3) 4 (0.6) 0 (0.0) infection / other health problem 35 (10.0) 71 (22.2) 106 (15.8) 7 (14.0) congenital 0 (0.0) 56 (14.9) 56 (7.0) 0 (0.0) current prosthesis usern (%) yes 211 (60.1) 261 (69.4) 472 (64.9) 50 (100.0) no 140 (39.9) 115 (30.6) 255 (35.1) 0 (0.0) users primary prosthesis typen (%) body-powered 155 (73.5) 155 (59.4) 310 (65.7) 41 (82.0) myoelectric 44 (20.9) 72 (27.6) 116 (24.6) 6 (12.0) hybrid 0 (0.0) 4 (1.5) 4 (0.9) 0 (0.0) cosmetic 8 (3.8) 20 (7.7) 28 (5.9) 2 (4.0) sport 4 (1.9) 6 (2.3) 10 (2.1) 1 (2.0) unknown 0 (0.0) 4 (1.5) 5 (0.9) 0 (0.0) hours of daily prosthesis usen (%) less than 2 hours 40 (19.1) 45 (17.6) 85 (18.2) 9 (18.0) 2 to less than 4 hours 28 (13.3) 26 (10.1) 54 (11.6) 12 (24.0) 4 to less than 8 hours 38 (18.1) 37 (14.4) 75 (16.1) 5 (10.0) 8 to less than 12 hours 43 (20.5) 62 (24.1) 105 (22.5) 10 (20.0) 12 hours or more 61 (29.1) 87 (33.9) 148 (31.7) 14 (28.0) https://doi.org/10.33137/cpoj.v5i1.37873 5 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj item category curves, and the presence of any differential item functioning (dif). we removed items with “moderate to large” dif (> 0.64) as defined by zwick.33 item-person maps and reliability we used rasch item-person maps for each factor to evaluate how the range and position of item measure distributions corresponded to the range and position of the person score generated from all items within the factor. we evaluated person reliability (ability to discriminate between persons, or traditional test reliability) as well as item reliability using rasch models. the test information function was used to determine the ranges of person scores with reliability ≥ 0.9 and ≥ 0.8. given the smaller number of items completed by non-prosthesis users, we repeated person reliability analyses in the sub-sample that did not utilize a prosthesis. cronbach’s alpha was used to assess internal consistency of the final factors. transformation and scoring rasch summary scores were calculated on a logit scale for the final item set. person logit scores were then standardized into a t-score matrix, and conversion scoring tables were created (for those with no missing data). test-retest reliability and calculation of minimal detectable change fifty participants completed the phone survey twice within 2 weeks (mean 7.8 (sd 3.0), range 3-14 days). these data were used to assess test-retest reliability via the shrout and fleiss intraclass correlation coefficient (icc) type 3,1. we calculated minimal detectable change (mdc) at 90% and 95% confidence levels using the icc and pooled standard deviation of factor scores (at interviews 1 and 2). results characteristics of participants in subsample 1, subsample 2, and the test-retest reliability sample are shown in table 2. the item pool utilized in field testing, items not retained, and items in the final psychosocial adjustment to amputation measure are shown in table 3. all decisions for dropping items as a result of efa and cfa analyses are shown in the figure 1 flow chart. factor analyses efa fit indices for a one-factor solution were not acceptable (cfi=0.83, tli=0.80, rmsea=0.15) and eigenvalue ratios for the first and second factor solutions did not suggest a unidimensional scale (9.28/2.84 <4). table 3: the item pool utilized in field testing, items not retained and items in the final modified psychosocial adjustment to amputation subscales. note: italicized text indicates items limited to prosthesis users. items used in field testing item dropped final 2-factor satisfaction scales factor 1: adjustment to limitation i have adjusted to having a prosthesis i have adjusted to having a prosthesis as time goes by, i accept my prosthesis more as time goes by, i accept my prosthesis more i feel that i have dealt successfully with this trauma in my life i feel that i have dealt successfully with this trauma in my life although i have an artificial limb, my life is full although i have an artificial limb, my life is full i have gotten used to wearing a prosthesis i have gotten used to wearing a prosthesis i don't care if somebody looks at my prosthesis x i find it easy to talk about my prosthesis i find it easy to talk about my prosthesis i have difficulty in talking about my limb loss in conversation x i have adjusted to being an amputee i have adjusted to being an amputee i don't care if somebody looks at my stump x factor 2: work and independence a prosthesis interferes with the ability to do my work a prosthesis interferes with the ability to do my work having a prosthesis makes me more dependent on others than i would like to be having a prosthesis makes me more dependent on others than i would like to be having a prosthesis limits the kind of work that i can do having a prosthesis limits the kind of work that i can do being someone with a limb difference means that i can't do what i want to do being someone with a limb difference means that i can't do what i want to do having a prosthesis limits the amount of work that i can do having a prosthesis limits the amount of work that i can do having an amputation limits the kind of work that i can do having an amputation limits the kind of work that i can do having an amputation limits the amount of work that i can do having an amputation limits the amount of work that i can do having an amputation makes me more dependent on others than i would like to be having an amputation makes me more dependent on others than i would like to be my amputation interferes with the ability to do my work my amputation interferes with the ability to do my work https://doi.org/10.33137/cpoj.v5i1.37873 6 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj parallel analysis indicated a two components solution. one item (“i don’t care if somebody looks at my prosthesis”) had lower factor loadings for both factors (<0.3) and was dropped. this resulted in a two-factor model with 9 items in each factor (cronbach’s alpha = 0.90 and 0.84) with acceptable model fit (cfi=0.950, tli=0.943, rmsea=0.084). the rmsea values for unidimensional model fit for were large for factor 1 (cfi=0.963, tli=0.950, rmsea=0.105) and factor 2 (cfi=0.947, tli=0.930, rmsea=0.156). therefore, we further explored unidimensionality by confirming that the ratio of the first and second eigenvalues was >4. we then stratified the sample by prosthesis users (yes vs. no) and repeated the analyses (not shown) to confirm that the factor structure was similar for both prosthesis users and non-users. cfa fit indices for the unstratified model were (cfi=0.934, tli=0.925, rmsea=0.100). rmsea for each factor were somewhat large (0.138 and 0.193). however, residual correlations were <0.2, eigenvalue ratios were >4, and all eigenvalues except for the first were <1.0. thus, we concluded that each factor had a unidimensional structure. the factors were labeled based on their content as: 1) adjustment to limitation, and 2) work and independence. calibration and dif analyses we used data from the full sample in rasch partial credit models and examined monotonicity of responses and item calibrations. in the adjustment to limitation factor, monotonicity criteria were not met for the item “as time goes by, i accept my prosthesis more.” to address this, we merged the neutral category with the “agree” category for factor scoring. after adjustment for this one item, there was no violation of monotonicity. in the work and independence factor, the monotonicity criteria were met for all items. in both factors, the neutral response category (“neither disagree nor agree”) had a low probability of selection in most items. we explored whether adjusting the model to treat selection of the neutral category as an extra factor fit the data better. we found that the extra factor only affected 6% of respondents, and the figure 1: flow diagram of item reduction and mapping onto factors. two-factor efa in subsample 1 18 items adjustment to limitation: 9 items work and independence: 9 items 7 items removed 2 items: dif and misfitting 9 items removed 1 item: factor loading<0.3 19 items rasch model in combined samples cfa in subsample 2 rasch model in combined samples cfa in subsample 2 https://doi.org/10.33137/cpoj.v5i1.37873 7 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj adjusted and unadjusted person score correlation was near 1. conceptually, there was no basis to merge this neutral category with other categories. therefore, we kept the neutral response category. in residual factor analysis, unexplained variance in the first contrast was <10% for both factors, and 59.7% and 74.8% of the variance was explained by the measures. calibrations for both factors are shown in table 4. in the adjustment to limitation factor, two items were dropped due to both poor fit and moderate to large dif by sex: “i have difficulty talking about limb loss in conversation” (infit=1.34, outfit=1.67, more difficult for men) and “i don’t care if somebody looks at my stump” (infit=1.19, outfit=1.56, more difficult for women). after dropping these items and reanalyzing dif, we observed that two items had slight to moderate dif by sex (“although i have an artificial limb, my life is full”) and laterality (“i find it easy to talk about my prosthesis”). in the work and independence factor, there was slight to moderate dif by sex (women had more difficulty with “having an amputation makes me more dependent on others than i would like to be”). there was also slight to moderate dif for three items by laterality (those with bilateral amputation had more difficulty). reliability rasch item-person maps for both subscales (figure 2) showed that item difficulties (including the lowest and highest categories) sufficiently covered the range of person ability scores. rasch reliability correlation coefficients for factor 1 were 0.70 for person reliability and 0.95 for item reliability. in factor 2, the person reliability correlation coefficient was 0.87 and the item reliability correlation coefficient was 0.99. given that non-prosthesis users only completed two items in the adjustment to limitation subscale, we examined reliability of this factor for nonusers and found that person reliability was 0.49. however, after removing extreme cases (those with highest or lowest responses for every item), the person reliability was 0.73. in the adjustment to limitation subscale, 87% of respondents had scores in the range (22.9 to 61.6) with a score reliability of 0.8 or higher (figure 3). in the work and independence subscale, 96% of respondents had scores (29.1 to 70.6) with a reliability at 0.8 or higher (figure 3). cronbach alpha was 0.82 and 0.90 for the adjustment to limitation and work and independence subscales respectively, indicating good internal consistency. icc (type 3,1) was 0.63 for the adjustment to limitation subscale and 0.80 for the work and independence subscale indicating moderate and good test-retest reliability, respectively (table 5). mdc 90 and 95 for the adjustment to limitation subscale were 17.7 and 14.9, respectively. mdc 90 and 95 for the work and independence subscale were 13.0 and 10.9, respectively. discussion our objective was to create a psychosocial adjustment scale for persons with ula that could be used in research and clinical practice for upper prosthesis users and nonusers alike, overcoming a limitation of the tapes-ula psychosocial adjustment subscale which is targeted to prosthesis users only. the strengths of this study include the large sample size and a robust sample of women with ula. the measure that we developed could be used as a screening tool in clinical practice to identify persons with poor psychosocial adjustment who might benefit from referral to behavioral health care providers. a copy of the final measure is provided in appendix b. given our sample size and characteristics, we were able to evaluate the extent of differential item functioning across key population categories. we field tested a 19-item set in a sample that included 472 prosthetic users and 255 nonusers. the new psychosocial adjustment to amputation measure we developed contains two subscales: a 7-item adjustment to limitation scale and a 9-item work and independence subscale. the new subscales had sound structural validity, good person and item reliability, and moderate to good test-retest reliability. no retained items had moderate to large dif by sex, age, prosthesis use, or laterality. our work has application for future studies of psychosocial adjustment to ula. prior studies in this area were limited to persons who use a prosthesis.9,16 we provided estimates of minimal detectable change (mdc) that can be used when interpreting change in scores at an individual level in longitudinal studies of psychosocial adjustment. while we believe that our tool is useful in its present state, further research is needed to enhance reliability of the adjustment to limitation subscale. this scale contains only two items that can be completed by persons who do not use a prosthesis and as such has lower reliability for non-users. this finding suggests that this subscale should be used cautiously for persons who do not use a prosthesis and that it may not be appropriate for use at the person level for determining change in adjustment to limitation in persons who do not use a prosthesis. in contrast, the work and independence subscale contains 5 items that are pertinent to persons who do not use a prosthesis and had stronger reliability. we recommend that additional items be developed and added to the adjustment to limitation subscale to enhance its reliability. limitations our study has several limitations. first, our study activities were conducted in english language only and with persons from the united states. our findings need to be replicated with translated versions and with english speaking persons from other countries. https://doi.org/10.33137/cpoj.v5i1.37873 8 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj table 4: partial credit model of adjustment to limitation and work and independence subscales (n=727). model infit outfit measure se mnsq zstd mnsq zstd factor 1: adjustment to limitation i have gotten used to wearing a prosthesis 41.89 0.32 0.86 -1.5 0.86 -1.4 as time goes by, i accept my prosthesis more 40.97 0.55 1.12 1.2 1.06 0.5 although i have an artificial limb, my life is full 40.65 0.37 1.16 1.6 1.10 1.0 i have adjusted to having a prosthesis 40.46 0.37 0.90 -1.0 0.75 -2.6 i find it easy to talk about my prosthesis 39.08 0.41 1.19 1.9 1.12 1.2 i feel that i have dealt successfully with this trauma in my life 37.10 0.32 0.91 -1.1 0.91 -1.1 i have adjusted to being an amputee 36.96 0.32 0.92 -1.0 1.32 3.0 factor 2: work and independence having an amputation limits the kind of work that i can do 55.36 0.28 1.04 0.7 0.95 -0.6 having a prosthesis limits the kind of work that i can do 54.02 0.34 1.04 0.5 1.08 0.8 having an amputation limits the amount of work that i can do 51.79 0.22 0.84 -3.1 0.82 -2.8 having an amputation makes me more dependent on others than i would like to be 50.67 0.22 0.99 -0.1 1.00 0.0 having a prosthesis limits the amount of work that i can do 50.17 0.34 0.88 -1.9 0.90 -1.3 having a prosthesis makes me more dependent on others than i would like to be 50.00 0.34 0.97 -0.4 0.96 -0.5 being someone with a limb difference means that i can't do what i want to do 49.22 0.22 1.04 0.7 1.20 3.2 a prosthesis interferes with the ability to do my work 47.88 0.34 1.14 2.2 1.31 4.0 my amputation interferes with the ability to do my work 47.88 0.22 1.09 1.7 1.25 3.9 figure 2: adjustment to limitation (top) and work and independence (bottom) item-person maps. note: the histogram of the sample score distribution is shown on the left and level of person ability with 50% probability of selecting each category (vs any higher category) for each item is shown on the right. adjustment to limitation work and independence adjusted dealt with trauma talk about prosthesis adjusted having prosthesis life full accept prosthesis used to wearing prosthesis sample frequency sample frequency amputation work interference prosthesis work interference can’t do what i want prosthesis dependence prosthesis amount work amputation dependence amputation amount work prosthesis kind work amputation kind work t s c a le t s c a le https://doi.org/10.33137/cpoj.v5i1.37873 9 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj second, males in our sample were predominantly veterans, while the majority of women were non-veterans. despite this difference, we found only minor differential item functioning by sex in the work and independence subscale. although we evaluated differential item functioning at the item level, this study did not compare overall scale scores by sex. these types of comparisons will need to be conducted in future studies. our findings may be limited to older persons, given that the mean age of our sample was 61, suggesting findings may not be representative of younger persons. additionally, the sample was predominately white and non-hispanic, limiting the generalizability to persons from less diverse backgrounds. further research is needed to assess how findings may vary by race and ethnicity. another limitation of the study is that all data were collected by interviewer administration by telephone. this mode of administration was selected to facilitate response rates and reduce respondent burden, given that the psychosocial item set was administered as part of a larger study of participantreported measures, with interviews lasting about 45 minutes. we acknowledge that respondents did not have copies of the measures or response categories. we made special efforts to customize the instructions to make telephone administration clear and study interviewers were carefully trained, professional survey staff members. further research is needed to examine the revised measure when administered by paper and pencil or electronically, and to compare results by mode of administration. we provided estimates of test-retest reliability and estimates of mdc values. our test-retest subsample was only 4% female while the overall sample was 20% female. therefore, these data should be considered preliminary and limited to men with ula. conclusion we developed a new tool to measure psychosocial adjustment in persons with ula and examined its measurement properties. the result was a 7-item adjustment to limitation subscale and a 9-item work and independence subscale with sound structural validity, good reliability, and evidence supporting test-retest reliability. both scales can be used for persons with ula to assess the table 5: psychosocial adjustment to amputation subscale iccs and mdcs. n interview 1: mn (sd) interview 2: mn (sd) icc (95% ci)* mdc 90 mdc 95 adjustment to limitation 50 51.5 (10.7) 52.6 (10.2) 0.63 (0.42, 0.77) 14.9 17.7 work and independence 50 50.6 (10.4) 51.1 (10.4) 0.80 (0.67, 0.88) 10.9 13.0 *ci: confidence interval, icc: intraclass correlation coefficient, mdc: minimal detectable change. note: we interpreted reliability with icc <0.50 considered poor, 0.50-0.75 moderate, 0.75-.90 good and >0.90 excellent. 34 figure 3: adjustment to limitation (top) and work and independence (bottom) test information function plots. https://doi.org/10.33137/cpoj.v5i1.37873 10 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj important construct of psychosocial adjustment and identify persons who might benefit from behavioral health referral regardless of whether they use a prosthesis. however, the adjustment to limitation subscale has marginal reliability in the nonuser subgroup. acknowledgements this work was supported by the united states (u.s.) department of veterans affairs, rehabilitation research and development service. the contents do not represent the views of the u.s. department of veterans affairs or the united states government. we thank all participants for their involvement and the department of veterans affairs for their support, including study staff eileen small and john davey. declaration of conflicting interests all authors declare that they have no conflict of interests. author contribution linda j. resnik: conceptualization, data interpretation, manuscript, writing, project administration, funding acquisition. pengsheng ni: statistical methodology, data analysis, visualization and interpretation. matthew l. borgia: statistical methodology, data analysis, visualization and interpretation, writing and editing. melissa a. clark: study design, survey design, data interpretation, manuscript review and revision. sources of support department of veterans affairs rehabilitation research and development service a2936-r and a9264-s. sponsors had no role in study design, collection, analysis, and interpretation of data. ethical approval the study was approved by va central institutional review board, and all participants gave oral informed consent as approved by the irb. references 1.mckechnie ps, john a. anxiety and depression following traumatic limb amputation: a systematic review. injury. 2014;45(12):1859-66. doi: 10.1016/j.injury.2014.09.015 2.hill a, niven ca, knussen c. the role of coping in adjustment to phantom limb pain. pain. 1995;62(1):79-86. doi: 10.1016/03043959(94)00253-b 3.gallagher p, maclachlan m. psychological adjustment and coping in adults with prosthetic limbs. behav med. 1999;25(3):11724. doi: 10.1080/08964289909596741 4.livneh h, antonak rf, gerhardt j. psychosocial adaptation to amputation: the role of sociodemographic variables, disabilityrelated factors and coping strategies. int j rehabil res. 1999;22(1):21-31. doi:10.1097/00004356-199903000-00003 5.desmond dm. coping, affective distress, and psychosocial adjustment among people with traumatic upper limb amputations. j psychosom res. 2007;62(1):15-21. doi: 10.1016/j.jpsychores.2006.07.027 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intraclass correlation coefficients for reliability research. j chiropr med. 2016;15(2):155-63. doi: 10.1016/j.jcm.2016.02.012 https://doi.org/10.33137/cpoj.v5i1.37873 https://cran.r-project.org/package=psych 12 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj appendix a measure used in field testing thinking about your upper limb amputation, how much do you disagree or agree with each of the following statements? strongly disagree disagree neither disagree nor agree agree strongly agree don’t know/ not sure [do not read] refused [do not read] a. i have adjusted to being an amputee [would you say strongly disagree, disagree, neither disagree nor agree, agree, or strongly agree?] 1 2 3 4 5 98 99 b. i feel that i have dealt successfully with this trauma in my life 1 2 3 4 5 98 99 c. i don't care if somebody looks at my stump 1 2 3 4 5 98 99 d. i have difficulty in talking about my limb loss in conversation 1 2 3 4 5 98 99 e. my amputation interferes with the ability to do my work 1 2 3 4 5 98 99 f. having an amputation limits the kind of work that i can do 1 2 3 4 5 98 99 g. having an amputation limits the amount of work that i can do 1 2 3 4 5 98 99 h. having an amputation makes me more dependent on others than i would like to be 1 2 3 4 5 98 99 i. being someone with a limb difference means that i can't do what i want to do 1 2 3 4 5 98 99 [ask if user] thinking about your prosthesis, how much do you disagree or agree with each of the following statements? strongly disagree disagree neither disagree nor agree agree strongly agree don’t know/ not sure [do not read] refused [do not read] a. i don't care if somebody looks at my prosthesis [would you say strongly disagree, disagree, neither disagree nor agree, agree, or strongly agree?] 1 2 3 4 5 98 99 b. i have adjusted to having a prosthesis 1 2 3 4 5 98 99 c. as time goes by, i accept my prosthesis more 1 2 3 4 5 98 99 d. although i have an artificial limb, my life is full 1 2 3 4 5 98 99 e. i have gotten used to wearing a prosthesis 1 2 3 4 5 98 99 f. i find it easy to talk about my prosthesis 1 2 3 4 5 98 99 g. a prosthesis interferes with the ability to do my work 1 2 3 4 5 98 99 h. having a prosthesis limits the kind of work that i can do 1 2 3 4 5 98 99 i. having a prosthesis limits the amount of work that i can do 1 2 3 4 5 98 99 j. having a prosthesis makes me more dependent on others than i would like to be 1 2 3 4 5 98 99 https://doi.org/10.33137/cpoj.v5i1.37873 13 resnik l.j., ni p., borgia m.l., clark m.a. a psychosocial adjustment measure for persons with upper limb amputation. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.8. https://doi.org/10.33137/cpoj.v5i1.37873 issn: 2561-987x psychosocial adjustment after upper limb amputation resnik et al., 2022 cpoj appendix b subject number  date:// mon/day/year psychosocial adjustment to amputation measure 1.thinking about your upper limb amputation, please indicate how much you disagree or agree with each of the following statements. strongly disagree disagree neither disagree nor agree agree strongly agree adjustment to limitation i have adjusted to being an amputee 1 2 3 4 5 i feel that i have dealt successfully with this trauma in my life 1 2 3 4 5 work and independence my amputation interferes with the ability to do my work 5 4 3 2 1 having an amputation limits the kind of work that i can do 5 4 3 2 1 having an amputation limits the amount of work that i can do 5 4 3 2 1 having an amputation makes me more dependent on others than i would like to be 5 4 3 2 1 being someone with a limb difference means that i can't do what i want to do 5 4 3 2 1 2. thinking about your prosthesis, please indicate how much you disagree or agree with each of the following statements. strongly disagree disagree neither disagree nor agree agree strongly agree adjustment to limitation i have adjusted to having a prosthesis 1 2 3 4 5 as time goes by, i accept my prosthesis more 1 2 3 3 4 although i have an artificial limb, my life is full 1 2 3 4 5 i have gotten used to wearing a prosthesis 1 2 3 4 5 i find it easy to talk about my prosthesis 1 2 3 4 5 work and independence a prosthesis interferes with the ability to do my work 5 4 3 2 1 having a prosthesis limits the kind of work that i can do 5 4 3 2 1 having a prosthesis limits the amount of work that i can do 5 4 3 2 1 having a prosthesis makes me more dependent on others than i would like to be 5 4 3 2 1 https://doi.org/10.33137/cpoj.v5i1.37873 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 3, issue 1 2020 literature review jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://doi.org/10.33137/cpoj.v3i1.33931 1 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 literature review the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review jamieson a.g, murray l, buis a* department of biomedical engineering, university of strathclyde, wolfson centre, 106 rottenrow, glasgow, g4 0nw, scotland, uk. introduction the limb amputation is increasingly prevalent, and it is projected that the number of individuals with limb loss in the united states by 2050 will be 1 in 85, with 65% of all amputation cases being classified as a lower limb amputation.1 the primary causes of amputation are peripheral vascular disease and physical trauma, with the former cause representing 82% of amputation cases.2 lower-limb amputation can create physical, socioeconomical and psychological barriers towards the individual’s physical activity. these barriers include having a poorly fitted prosthesis, insufficient resources for physical activity, lack of motivation to participate in activities and a lack of self-efficacy.3 as such, individuals with lower limb amputation (illas) are generally less physically active than individuals without limb loss.4 by maintaining sufficient levels of physical activity, illas will over time see improvements in their heart and lung functionality and can improve perceptions of the individual’s quality of life, selfesteem and body image.5-7 interventions which have focused on improving the physical activity of illas can be broken down into two major categories; prosthetic interventions and behavioural interventions. in a prosthetic intervention, the subject is fit open access volume 3, issue 1, article no.2. 2020 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: interventions which have focused on improving the physical activity of individuals with lower limb amputation can be mostly categorized into behavioural-based and prosthetic-based interventions. the aim of this review was to assess the quality of these interventions, and to identify the key gaps in research in this field. methodology: the databases of scopus, pubmed, embase, medline and web of science were searched between september and december of 2019 for articles relating to physical activity, amputees and interventions. articles were assessed quantitively based on internal validity, external validity and intervention intensity. findings: sixteen articles (5 behavioural, 11 prosthetic) were assessed. both approaches had comparable methodological quality and mixed efficacy for producing a significant change in physical activity outcomes. almost all interventions used a simplistic measurement of activity as their outcome. conclusions: there is an insufficient amount of studies to assess the overall efficacy of behavioural interventions in regard to how they impact on physical activity behaviour. however, the increase of quality of the methodology in the more recent studies could indicate that future interventions will retain similar levels of quality. prosthetic interventions have shown no major improvement in efficacy compared to similar reviews and may need to utilise more advanced prosthetic components to attain significant changes in physical activity. activity outcomes should expand into more complex activity measurements to properly understand the physical activity profile of people with lower limb amputation. article info received: april 2, 2020 accepted: may 11, 2020 published: may 19, 2020 citation jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020; volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i 1.33931 keywords amputation, rehabilitation, amputee, lower limb amputation, physical activity, lower limb prosthetics, exercise. *corresponding author dr. arjan buis, department of biomedical engineering, university of strathclyde, wolfson centre, 106 rottenrow, glasgow, g4 0nw, scotland, uk. e-mail: arjan.buis@strath.ac.uk orcid: https://orcid.org/0000-0003-3947-293x https://doi.org/10.33137/cpoj.v3i1.33931 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v3i1.33931 https://doi.org/10.33137/cpoj.v3i1.33931 mailto:arjan.buis@strath.ac.uk https://orcid.org/0000-0003-3947-293x 2 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj with a prosthetic component, and their physical activity is typically compared with subjects wearing a variant of that prosthetic component.8 marked improvements in physical activity rates indicate that the prosthetic intervention has helped the patient carry out more physical activity, whether by making them feel more comfortable wearing the prosthesis, reducing the socket pain or wearing during gait, or any other number of potential physical or psychological factors. a behavioural intervention on the other hand will aim to employ behavioural change techniques such as goal setting, self-monitoring of behaviour and behaviour substitution to the subjects,9 which can then be measured in quantifiable activity, such as the number of steps taken per day.10 other categories of physical activity interventions exist, such as massage interventions,11 however the paucity of these interventions makes them unsuitable for the scope of this review. the primary aim of this review was to assess the quality of prosthetic and behavioural interventions when they are used to modify physical activity behaviour or physical activity performance in illas. additionally, the review was also established to identify and address the key gaps in research in this field. methodology search strategy and screening process literature searches were conducted in a period spanning september – december 2019, using the electronic databases of scopus, pubmed, web of science, and the combined databases of embase and medline via ovid. additional hand searched articles from previous research were also included. the search strategy used medical subject heading terms relating to the illa population (“amputee”, “amputees”, “leg amputation”, “lower limb amputation”, “physical disability” or “disabled persons”), terms relating to physical activity ("fitness", "exercise", "physical activity" or "physical activities") and terms relating to an intervention (“intervention” or “interventions”). inclusion criteria an outcome measure is any measurement that evaluates the activity (e.g step count or the energy expenditure generated from performing physical activity) of an illa, whether through self-reported activity monitoring (e.g an activity diary), activity evaluation questionnaires12-14 or objective activity monitoring devices (e.g a pedometer). all levels of lower limb amputation were included , so long as the subjects utilised a prosthesis or other walking support devices and were not exclusively wheelchair bound. only studies that were available in full text and in the english language were considered for inclusion. each article went through three checks for eligibility when screening; whether the title was appropriate, whether the article was a duplicate of an already identified paper, and whether the abstract appeared to provide eligible content for the review. exclusion criteria any multifaceted intervention that contained prosthetic or behavioural components were excluded, as it would not be possible to determine the individual efficacy of that component on the physical activity outcomes. case studies were not included due to their lack of generalizability. assessment of methodology quality articles included for full review used an analysis structure devised from a combination of assessment methodologies. internal validity, external validity and intervention intensity were used to determine the quality of each article’s methodology. internal and external validity was assessed based on modified criteria by salminen et al.,15 which itself was based on a modified version of internal validity criteria used in borghouts et al.16 and by external validity used in shekelle et al.17 intervention intensity was used in ma and gini’s18 systematic review of physical activity interventions on the physically disabled, which was based on a criteria list created by hendrie et al.19 a full explanation of how the assessment criteria was marked is contained in appendix a. results screening process figure (1) shows a visualisation of the screening process. a total of 7,584 articles were identified and screened through scopus, pubmed, web of science, embase and medline. after removing duplicates and unsuitable articles, 17 potentially eligible papers were identified. an additional 4 articles were found from various sources that were researched prior to the inception of the review. two of the eligible articles20,21 did not specify whether the participants with limb loss had upper or lower limb loss. after contacting the correspondents, it was ensured that illas were included in both studies. five studies were excluded in total. miller et al.22 was excluded based on the fact that their intervention was ongoing. gailey et al.23 and ladlow et al.24 were both excluded as they described a multifaceted intervention, where it was not clear how each component individually affected physical activity behaviours. van der ploeg et al.25 described the same intervention that was used in one of the other eligible articles (van der ploeg et al.21) but used different outcome measures. likewise, the intervention originally described by morgan et al.8 was repeated in mcdonald et al.26 and did not provide a description of the intervention procedure. thus, a total of 16 articles were used for full analysis. https://doi.org/10.33137/cpoj.v3i1.33931 3 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj study characteristics the study characteristics of each intervention is illustrated in appendix (b). one of the included papers, klute et al.27 was approached differently; as the paper described two individual interventions, both interventions were assessed independently: klute et al.27 [a] refers to the intervention that compared shock-absorbing pylons and rigid pylons, while klute et al.27 [b] refers to the intervention that compared mechanical-controlled and microprocessorcontrolled prosthetic knees. • behavioural interventions aside from delehanty and trachsel,28 the behavioural studies were randomized, controlled trials. two studies used telephone communication as the primary means of delivering the intervention (christiansen et al.29; littman et al.30), while kosma et al.,20 delehanty and trachsel,28 and van der ploeg et al.21 used e-mail, group meetings and counselling sessions respectively to communicate. a range of physical activity assessment techniques were applied across the studies. kosma et al.20 and van der ploeg et al.21 used standardized questionnaires while the two most recent studies, christiansen et al.29 and littman et al.,30 used objective activity monitoring via accelerometers. van der ploeg et al.21 also used a nonstandardised customised questionnaire to measure sport related activities. delehanty and trachsel28 used a nonstandardised ‘rehabilitation status questionnaire’ to measure their outcomes. behavioural interventions produced at least one significant change in physical activity behaviour in 3 out of the 5 studies. these positive significant effects were the increase in step count, the decrease of sedentary time, the increase in activity level for vacation, sport participation, and the ability to meet daily physical activity requirements. in kosma et al.20 and littman et al.,30 no significant outcomes could be identified. • prosthetic interventions with the exception of buis et al.31 and selles et al.,32 prosthetic interventions followed a crossover trial design wherein participants would be randomly assigned with one type of prosthetic, go through a period of accommodation, have their physical activity monitored, and then be fitted with the other type of prosthetic and repeat the process. in buis et al.31 and selles et al.,32 participants only received the intervention or the control, not both. the range of the types of prosthetic interventions applied was diverse, with the most frequently occurring type of intervention being the prosthetic knee (n=4). other prosthetic interventions analysed the pylon, socket (n =2 each), liner, suspension, feet and adapter (n =1 each). all prosthetic knee interventions involved comparing a microprocessor-controlled knee to a mechanical-controlled knee. intervention periods ranged from <1 week to 18 weeks, with the accommodation period often controlling how long the intervention lasted. a majority of the studies used identical or similar activity monitoring devices and outcomes; 66% (8/12) of the studies used the ankle based stepwatch activity monitor (sam) (orthocare innovations, mountlake terrace, wa, usa) as their measuring device. other measuring devices included the activpal, actigraph and the so-called “activity monitor” used in one of the reviews.32 they were all accelerometerbased activity monitors. the only study to not use an accelerometer was kaufman et al.33 which used the doublylabelled water (dlw) method to obtain estimated energy expenditure. all sam studies measured stepping activity to some degree (daily step count, weekly step count, step distance). other measurements taken were the time spent during bouts of activity and the number of body posture transitions. the efficacy of the prosthetic interventions was overall mixed, with 7/12 studies finding no significant differences in any activity measurements taken. liner, suspension and adapter designs all had significant impact on the activity articles found in scopus (n = 2309) id e n ti fi c a ti o n articles found for general assessment (n = 7584) duplicate articles (n = 3772) articles excluded based on title or abstract (n = 3795) articles assessed for eligibility (n = 17) articles excluded based on content (n = 5) articles included for full analysis (n = 16) s c re e n in g e lig ib ili ty in c lu d e d articles found in pubmed (n = 1340) articles found in web of science (n = 1782) articles found in embase+ ovid medline (n = 2153) articles found in other reviews (n = 4) figure 1: flowchart diagram of the screening process. https://doi.org/10.33137/cpoj.v3i1.33931 4 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj measurements, while pylon and feet designs had no significant impact. prosthetic knees had mixed results; no significant differences were found when step activity was measured, but significant differences were found in the estimated energy expenditure and activity levels. due to the small amount of studies available for each design component, a relationship between the type of component and physical activity outcomes could not be ascertained. internal validity • behavioural interventions the internal validity of the 5 behavioural studies is demonstrated in table 1. christiansen et al.29 and van der ploeg et al.21 had the highest internal validity, obtaining 8 out of a possible 11 points each, while kosma et al.20 and delehanty and trachsel28 had the lowest with 5 points each. the only criteria which was successfully achieved by all behavioural studies was having the outcome measures and data presentation congruent with the study aims. no criteria were unmet completely. • prosthetic interventions after conducting a student t-test on the means of the internal validity scores for the prosthetic and behavioural interventions, the difference in the means between the two kinds of interventions was found to be non-significant (p = 0.31). the study with the highest internal validity was kaufmen et al.33 with 9 points, while the lowest was klute et al.36 (2011) with 4 points. all prosthetic interventions successfully gave a sufficient description of their drop-outs (or had no drop-outs) and in utilising objective physical activity outcome measurements. the follow-up time of prosthetic interventions was found to be insufficient in most prosthetic interventions, only kaufmen et al.33 had a follow-up greater than 4 months. prosthetic interventions also performed poorly in having sufficient study size, reporting adherence to the intervention and checking for confounding variables. r e fe re n c e s u ff ic ie n t d e s c ri p ti o n o f s tu d y p o p u la ti o n s e le c ti o n s u ff ic ie n t d e s c ri p ti o n o f in c lu s io n a n d e x c lu s io n c ri te ri a s tu d y s iz e s u ff ic ie n t? ( > = 1 0 p a ti e n t y e a rs ) f o llo w u p t im e s u ff ic ie n t (> = 4 m o n th s ) p ro p o rt io n o f d ro p o u ts i s s u ff ic ie n tl y s m a ll (< = 2 0 % ) d ro p o u ts a re s u ff ic ie n tl y d e s c ri b e d o u tc o m e m e a s u re s & d a ta p re s e n ta ti o n m a tc h w it h s tu d y a im s c o n fo u n d e r c o n tr o l p e rf o rm e d p s y c h o m e tr ic p ro p e rt ie s o f th e m e a s u ri n g i n s tr u m e n t re p o rt e d o b je c ti v e m e a s u re m e n ts o f p h y s ic a l a c ti v it y c a rr ie d o u t a d h e re n c e t o i n te rv e n ti o n re p o rt e d ? t o ta l theeven et al.34 1 1 0 0 0 1 0 0 1 1 1 5 selles et al.32 1 0 0 0 0 1 1 0 1 1 0 5 segal et al.35 1 0 0 0 1 1 1 0 1 1 0 6 morgan et al.8 1 1 0 0 1 1 1 1 1 1 0 8 klute et al.36 1 0 0 0 0 1 0 0 0 1 1 3 klute et al. [b]27 1 1 0 0 0 1 1 0 1 1 0 6 klute et al. [a]27 1 1 0 0 1 1 1 0 1 1 0 7 kaufman et al.33 1 1 1 1 1 1 1 0 1 1 0 9 hafner et al.37 1 1 1 0 1 1 1 1 0 1 0 8 coleman et al.38 0 0 0 0 1 1 1 0 1 1 1 5 buis et al.31 0 0 0 0 1 1 1 1 1 1 0 6 berge et al.39 1 1 0 0 1 1 1 1 0 1 0 7 van der ploeg et al.21 0 1 1 1 1 1 1 1 0 0 1 7 littman et al.30 1 1 0 1 0 1 1 0 0 1 1 6 kosma et al.20 0 1 1 0 0 0 1 1 1 0 0 5 delehanty & trachsel 28 1 0 0 1 0 0 1 0 1 0 1 4 christiansen et al.29 1 1 0 0 1 1 1 0 1 1 1 7 table 1: internal validity scores. blue boxes indicate behavioural interventions and white boxes indicate prosthetic interventions. reference numbers are located in square brackets [ ]. https://doi.org/10.33137/cpoj.v3i1.33931 5 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj external validity • behavioural interventions external validity is displayed in table 2a. only one study (christiansen et al.29) obtained the maximum score for external validity, three studies acquired half of the maximum score (delehanty and trachsel,28 kosma et al.,20 van der ploeg et al.21). all studies described their intervention in detail. delehanty and trachsel28 was the only study that failed to describe clinically relevant outcome measures, which was due to their non-standardised activity monitoring assessment. the intervention used in christiansen et al.29 was the only intervention to show a clinically important effect in the outcome measures: there was a greater than 10% gain in daily step count between the control and intervention groups. • prosthetic interventions in comparison to behavioural interventions, prosthetic interventions had highly consistent performance in external validity, however their overall mean performances in a student t-test were nearly identical (p = 0.93). coleman et al.38 was the only study to achieve the maximum external validity, and just two studies had less than three points. the weakest performing, theeven et al.34 only obtained 1 point. the remaining studies all scored 3 points. there was a significant discrepancy between the size effect and the other 3 external validity criteria; only 2 studies had a 10% significant gain (i.e a clinically important gain) in outcomes relating to daily/fortnightly step count (coleman et al.38 and klute et al.36 (2011)), whereas between 10 and 11 studies were able to achieve the other 3 criteria. intervention intensity • behavioural interventions table 2b shows the intervention intensity calculated for each study. the highest scoring intervention was littman et al.,30 with the lowest being delahanty and trachsel.28 in general, the studies performed highly in terms of frequency of contact (every study contacted the participants on a weekly or bi-weekly basis) and type of contact (most were individual contact or group contact with an individual element). no study achieved a ‘4’ or higher in intervention duration (6 months or more), and all studies performed poorly in the reach category (only littman et al.30 and van der ploeg et al.21 provided more than one contact setting). external validity intervention intensity reference s tu d y p a rt ic ip a n ts d e s c ri b e d i n d e ta il? in te rv e n ti o n d e s c ri b e d i n d e ta il? c lin ic a lly re le v a n t o u tc o m e s m e a s u re d ? s iz e o f e ff e c t c lin ic a lly im p o rt a n t t o ta l in te rv e n ti o n d u ra ti o n f re q u e n c y o f c o n ta c t t y p e o f c o n ta c t r e a c h t o ta l theeven et al.34 1 0 0 0 1 1 4 5 1 11 selles et al.32 1 1 1 0 3 1 3 5 1 10 segal et al.35 1 1 1 0 3 1 3 5 1 10 morgan et al.8 1 1 1 0 3 1 3 5 1 10 klute et al.36 1 0 1 1 3 1 3 5 1 10 klute et al. [b]27 1 1 1 0 3 3 3 5 1 12 klute et al. [a]27 1 1 1 0 3 1 3 5 1 10 kaufman et al.33 1 1 1 0 3 4 2 5 1 12 hafner et al.37 1 1 1 0 3 5 3 5 1 14 coleman et al.38 1 1 1 1 4 4 3 5 3 15 buis et al.31 0 1 1 0 2 1 4 5 1 11 berge et al.39 1 1 1 0 3 1 3 5 1 10 van der ploeg et.al.21 0 1 1 0 2 2 4 5 3 14 littman et al.30 1 1 1 0 3 3 4 5 3 15 kosma et al.20 0 1 1 0 2 1 4 4 1 10 delehanty & trachsel 28 1 1 0 0 2 1 4 3 1 9 christiansen et al.29 1 1 1 1 4 3 4 5 1 13 table 2 (a,b): external validity and intervention intensity. blue boxes indicate behavioural interventions and white boxes indicate prosthetic interventions. a b https://doi.org/10.33137/cpoj.v3i1.33931 6 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj • prosthetic interventions the performance of the prosthetic interventions was once again comparable to the behavioural interventions (p = 0.51). the highest scoring prosthetic intervention was coleman et al.38 with 15 points, while multiple studies tied for the lowest score at 10 points. all studies achieved the maximum score for type of contact (all participants were interacted with individually). only one study, coleman et al.,38 had more than one method of interacting with the participants (the reach) via face-to-face and telephone communication. as most prosthetic interventions were carried out over a short time span, only 4 studies had an intervention length score of 2 or higher. discussion the research in this study was important to assess the current state of behavioural interventions and prosthetic interventions in how they modify the physical activity behaviour of illas. after all identified literature were assessed for their internal validity, external validity and intervention intensity, it was found that behavioural and prosthetic interventions had roughly equal efficacy when it came to generating a significant change in physical activity behaviours. statistically, the mean scores of internal validity, external validity and intervention intensity were equal between the two groups. therefore, this study has shown that neither intervention has proven to be more effective than the other. main findings • behavioural interventions behavioural interventions had mixed efficacy when it came to moderating physical activity in illas. only two studies identified (christiansen et al.29 and van der ploeg et al.21) had significant positive increases in physical activity behaviour in regards to daily step count, sport participation and the ability to meet pre-defined physical activity requirements. it is also important to consider that the findings of van der ploeg et al.21 have questionable impact on illas, as they only report their intervention’s impact on the general disabled population. delehanty and trachsel28 had a single positive result (increased holiday time) while the rest had no significant results. these findings differentiate from reviews which have looked at behavioural intervention studies for people with non-specific disabilities; castro et al.40 and lai et al.41 found significant positive increases in physical activity outcomes in 70% and 83% of identified studies respectively. the meta-analysis used in ma and ginis18 reported “small to medium sized effects” in the interventions towards physical activity outcomes. a possible explanation for these differing results is the lack of available studies relating specifically to illas: compared to the five articles found in this review, 38, 132 and 24 studies were identified in castro et al.,40 lai et al.41 and ma and ginis’s18 studies respectively. another possible explanation is that behavioural interventions may need to tailor the intervention around solving the illas’ barriers to physical activity, such as those identified in littman et al.3 despite the lack of evidence and the mixed results, there is some optimism in these findings; by considering that the more modern interventions applied in christiansen et al.29 and littman et al.30 had higher methodological quality than the older interventions, it is possible that future studies will retain a similar high level of methodological quality, which could lead to a more conclusive idea of how effective behavioural interventions are on the physical activity of illas in the future. • prosthetic interventions prosthetic interventions also had mixed effects on the physical activity of illas, with five out of twelve studies reporting significant effects. this finding is echoed by samuelsson et al.42 and pepin et al.43 who both reviewed the effects of prosthetic components on physical activity. in samuelsson et al.42 and pepin et al.43 five out of eight studies and five out of fourteen studies had significant impact on physical activity outcomes respectively. the findings of the review are highly comparable to samuelsson et al.42 as they used the same reviewing criteria (internal and external validity) and some of the same articles. the external validity was found to be scored identically in each of the shared articles, however there were some minor disagreements with internal validity criteria and scoring. for example, in the assessment of coleman et al.38 they scored 0 for reporting psychometric properties of the measuring instrument, while this review scored a 1. these discrepancies can be explained by the differing objectives that the review by samuelsson et al.42 had. in coleman et al.,38 the psychometric properties of the physical activity measuring instrument were reported, but not the questionnaires. as these questionnaires report on the impact of quality of life and participation in the individual’s community, which were critical topics in the review by samuelsson et al.,42 this likely explains why coleman et al.38 scored a 0 in their review for that particular element. the maximum discrepancy in internal validity scoring was ±1, so overall both reviews had a similar assessment of the shared articles. only one prosthetic intervention to moderate physical activity had been developed in the time between the review by pepin et al.43 and this review. considering this finding, it appears that the development of prosthetic interventions to moderate physical activity outcomes has stagnated. at best, they appear to have mixed efficacy, and even within the intervention type, results are inconsistent. for instance, all identified prosthetic knee interventions compared a microprocessor knee to a mechanical knee, and multiple outcomes were found; two papers reported no significant https://doi.org/10.33137/cpoj.v3i1.33931 7 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj results in activity outcomes,27,37 one reported significant improvement in favour of wearing the microprocessor knee,33 and one reported significant improvements in favour of wearing the mechanical knee.34 the review therefore concludes that prosthetic interventions are, in their current state, an unreliable method of improving physical activity outcomes. some promising developments in prosthetic technology could be incorporated into the design of future prosthetic interventions. for example, powered knees are a recently developed type of prosthetic knee that, compared to the more traditional microprocessor and mechanical knees, provide greater output in energy assistance and can help perform more demanding walking movements like climbing stairs.44 these inventions may be critical to obtaining definitive improvements in physical activity behaviour in illas. outcome measures in physical activity in the behavioural approach, two interventions used objective activity monitoring measurements,29,30 two interventions used subjective questionnaires,20,21 and two interventions used non-standardized questionnaires.21,28 by contrast, all prosthetic interventions used objective activity measurements. delehanty and trachsel28 used outcome measures that were the least effective and least informative; their rehabilitation status questionnaire prior to the study had not been found reliable or validated in any way, aside from piloting the questionnaire with some patients prior to the study. their outcome measures which included “church”, “shopping” and “banking” – are outdated by modern standards. in van der ploeg et al.,21 sport score and sport participation were assessed by a custom questionnaire which took into account the number of hours spent on the sport and the designated intensity of the sport in metabolic equivalent of tasks (mets) from a physical activity compendium.45 the authors did not provide further details of which sports were carried out and for how long, so it was impossible to identify which activities the illa population were participating in. these non-standardised forms of evaluation make it difficult to compare results across different studies and should be avoided in future investigations. van der ploeg et al.21 and kosma et al.20 made use of the “physical activity scale for individuals with physical disabilities” (pasipd) questionnaire to evaluate their programs.14 pasipd is a widely used and validated questionnaire.46 the questionnaire assesses physical activity by combining the number of hours spent performing a particular activity with the activity’s met equivalent. despite the questionnaire’s popularity, the pasipd has been found to show poor correlation with objective physical activity measurements,47 and so in future studies these questionnaires should also be avoided where possible, especially when the accuracy of the measurements is an important factor. christiansen et al.,29 littman et al.30 and all prosthetic studies used objective activity monitoring. by far the most common approach was to utilise the step activity monitor and then analyse the intervention by changes in some measurement of step activity. other devices such as the activpal and actigraph were also used but only to measure step count or vaguely defined ‘activity bouts’. while objective activity monitoring is much more reliable than self-report questionnaires in terms of accuracy,48 monitoring devices are over-reliant on stepping. stepping has strong associations with positive health outcomes such as a decrease in the risk of cardiometabolic adverse events,49 however it only gives a surface-level insight into the person’s activity – for instance, an illa who performs stationary exercises and stretches will appear to be inactive when monitored by an ordinary pedometer. kaufman et al.33 was the only study to measure energy expenditure via the doubly-labelled water effect. while its high precision makes the this method the gold standard for measuring energy expenditure,50 the primary limitation of this method is its complexity – the method requires ingesting an isotope which is then expunged through urination and analysed using mass spectroscopy. analysis must be carried out by a specialist, making it impractical to use for large sample sizes. another problematic issue is that there is no standardisation of energy readings applicable to amputees like mets are to non-amputees. using standard mets to assess non-amputees gives an unfair comparison due to lower energy expenditures51 and bodies such as the american college of sports medicine have yet to establish an equivalent system for illas. likewise, while there are government funded documents such the uk chief medical officers' physical activity guidelines to help set standards of physical activity for the general population,52 there is no equivalent document for illas. future interventions for physical activity monitoring should consider incorporating more complex measurements of activity. step count measurements could be expanded upon by being able to distinguish between uphill/downhill and upstairs/downstairs movement, and the associated energy expended from performing such motions. in addition, the interventions should break down the analysed data into a simple, digestible format such that the end user (i.e the illa) can sufficiently understand their data and know what they need to improve upon. limitation the selection of chosen articles for review was limited by the number of databases used for the literature search, and the authors’ english language bias. there is a reasonable possibility that the authors may have failed to identify more studies such as kosma et al.20 and van der ploeg et al.21 which do not mention an illa population within their abstract. this review may contain some reporting bias for the internal validity evaluation as the authors added two https://doi.org/10.33137/cpoj.v3i1.33931 8 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj additional criteria. to minimize this risk of bias, the authors conceived of these criteria before conducting the literature search. some reporting bias may come from the fact that only one author carried out the assessment of methodological quality, and so is limited to one individual’s perspective. conclusion after conducting a systematic review on scopus, pubmed, embase, medline and web of science, 16 studies were identified which assessed the physical activity of illas after the application of a prosthetic or behavioural intervention. ultimately, the lack of available studies makes it difficult to comment on the overall efficacy of behavioural interventions on illas, but the increase of quality of the methodology in the most recent studies identified give an optimistic indication that future interventions will have similar levels of methodological quality. there are a substantial amount of prosthetic interventions with good methodological quality, however the efficacy of these prosthetic interventions has stagnated, and may require implementing more technologically advanced prosthetic components to obtain a significant change in activity. future interventions should incorporate more sophisticated forms of activity measurement to give a more in-depth assessment of physical activity. acknowledgements the author of this article would to thank the university of strathclyde for providing the electronic resources required to access the reviewed papers for this research. declaration of conflicting interests mr. jamieson receives grants from pal technologies ltd as part of his phd funding, pal technologies manufactures the activpal which is one of the devices included in this review; co-author dr. arjan buis is an associate editor at the canadian prosthetics & orthotics journal. dr. arjan buis is also the main author of one of the reviewed articles. author contribution • alexander g. jamieson: responsible for researching and reviewing all included articles and writing the main body of the review. • laura murray: responsible for editing , supervision. • arjan buis: responsible for editing , supervision. sources of support this research was funded indirectly as part of the author mr. jamieson’s phd sponsorship. the sponsorship is jointly funded by the epsrc and pal technologies ltd. references 1.ziegler-graham k, mackenzie ej, ephraim pl, travison tg, brookmeyer r. estimating the prevalence of limb loss in the united states: 2005 to 2050. 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microprocessor-controlled prosthetic knees. arch phys med rehabil. 2008;89(7):1380-5. doi: 10.1016/j.apmr.2007.11.053 34.theeven pj, hemmen b, geers rp, smeets rj, brink pr, seelen ha. influence of advanced prosthetic knee joints on perceived performance and everyday life activity level of lowfunctional persons with a transfemoral amputation or knee disarticulation. j rehabil med. 2012;44(5):454-61. doi: 10.2340/16501977-0969 35.segal ad, kracht r, klute gk. does a torsion adapter improve functional mobility, pain, and fatigue in patients with transtibial amputation? clin orthop relat res. 2014;472(10):3085-92. doi: 10.1007/s11999-014-3607-9 36.klute gk, berge js, biggs w, pongnumkul s, popovic z, curless b. vacuum-assisted socket suspension compared with pin suspension for lower extremity amputees: effect on fit, activity, and limb volume. arch phys med rehabil. 2011;92(10):1570-5. doi: 10.1016/j.apmr.2011.05.019 37.hafner bj, willingham ll, buell nc, allyn kj, smith dg. evaluation of 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doi: 10.1016/j.apmr.2010.12.006 48.stepien jm, cavenett s, taylor l, crotty m. activity levels among lower-limb amputees: self-report versus step activity monitor. arch phys med rehabil. 2007;88(7):896-900. doi: 10.1016/j.apmr.2007.03.016 49.schmidt md, cleland vj, shaw k, dwyer t, venn aj. cardiometabolic risk in younger and older adults across an index of ambulatory activity. am. j. prev. med. 2009;37(4):278-84. doi: 10.1016/j.amepre.2009.05.020 50.berman e, swibas t, kohrt w, catenacci v, creasy s, melanson e, et al. maximizing precision and accuracy of the doubly labeled water method via optimal sampling protocol, calculation choices, and incorporation of 17o measurements. eur. j. clin. nutr. 2019. doi: 10.1038/s41430-019-0492-z 51.littman aj, boyko ej, thompson ml, haselkorn jk, sangeorzan bj, arterburn de. physical activity barriers and enablers in older veterans with lower-limb amputation. j rehabil res dev. 2014;51(6):895-906. doi: 10.1682/ jrrd.2013.06.0152 52.uk chief medical officers' physical activity guidelines. in: care dohs, editor. 2019. https://doi.org/10.33137/cpoj.v3i1.33931 11 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj appendix (a): descriptions of the rating criteria • internal validity an ideal study with the maximum internal validity should have a sufficient description of the study population selection and the inclusion and exclusion criteria. the study size (the product of the number of patients by the intervention length) should be greater than 10 patient years. the number of dropouts should be less than 20% of the total number included in the study, and the reasoning for dropouts should be sufficiently described (if there were no dropouts, both criteria were met by default). the follow-up time of the intervention should be at least 4 months. the study should check for confounding variables and report on the psychometric properties of the measuring instruments used for this criterion only instruments measuring physical activity were assessed. the outcome measures and data presented in the article should be in alignment with the study’s aims. two additional criteria were created and used for this study: “whether the activity monitoring was carried out with objective measuring devices” and “whether participant adherence to the intervention was recorded”. the former criterion was added because an objective measurement of physical activity gives an unbiased, quantitative response to the intervention. the latter criterion, which asks whether participants managed to fully participate in the intervention, was added because adhesion to the intervention can be a factor in the outcome of the study. each criterion was scored with a 1 (criteria was met) or a 0 (criteria was not met), making the maximum score for internal validity 11 points. • external validity the criteria used were as follows: whether the participants in the study and the intervention itself were described in sufficient detail, whether clinically relevant outcomes were used, and whether the size of effect on the outcomes were clinically important, having a gain greater than or equal to 10%. as with internal validity, each criterion was scored with a binomial outcome of 1 or 0, making the maximum score 4 points. • intervention intensity the intervention intensity score was calculated using four criteria which had a maximum score of 5 points each. the criteria were: the intervention’s duration (1 = <6 weeks, 2 = 6 to 11 weeks, 3 = 12 weeks to 5 months, 4 = 6 to 12 months, 5 = >12 months), frequency of contact between the intervention provider and the participant, (1 = annually, 2 = bimonthly to quarterly, 3 = monthly, 4 = weekly, 5 = daily) the type of contact, (1 = environmental at a physical, policy or legislative level, 2 = environmental with a small group or educational component involved, 3 = group contact, 4 = group contact with an individual component such as goal setting, 5 = individual) and the ‘reach’ how many ways the intervention interacts with the participant (1 = one setting, 3 = two settings, 5 = three or more settings). the total intervention intensity was calculated by the sum of the four factors, making the maximum score achievable 20 points. appendix (a) https://doi.org/10.33137/cpoj.v3i1.33931 12 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj appendix (b): characteristics of the included studies key summary: appendix b summarizes the characteristics of all included studies. the key findings of this appendix were: • behavioural interventions primarily employed randomized controlled study design, while nearly prosthetic interventions used crossover trial design. • interventions lasted on average 15 weeks, had 23 participants with an average age of 52 years. the participants primarily had unilateral amputation. • most interventions used step count or a derivation of step count as their activity outcome metric. • when activity monitoring was used, the most popular device for carrying out this task was the step activity monitor. • interventions had mixed efficacy when it came to improving physical activity behaviours, this was true for both behavioural and prosthetic based interventions. blue boxes indicate behavioural interventions, white boxes indicate prosthetic interventions. abbreviations: pasipd (physical activity scale for individuals with physical disabilities); sam (step activity monitor); illa (individual(s) with lower extremity amputation). 1: one illa received intervention while 3 others received control. illas made up 5% of the total population (n = 75). 2: 18 illas received the ‘rehabilitation and sport’ intervention, another 18 had the combined ‘rehabilitation and sport’ + ‘active after rehabilitation’ intervention, and 28 illas were in the control group. illas made up 6% of the total population (n = 993). 3: age was not specified for illas so the average age for all disability types was used. appendix (b) https://doi.org/10.33137/cpoj.v3i1.33931 13 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj appendix (b): characteristics of the included studies r e fe re n c e s tu d y d e s ig n s u m m a ry o f in te rv e n ti o n in te rv e n ti o n l e n g th f o llo w -u p t im e n o . o f il l a s c o n tr o ls a v e ra g e a g e o f a ll p a rt ic ip a n ts t y p e o f a m p u ta ti o n p a o u tc o m e m e a s u re s p a m e a s u ri n g in s tr u m e n t im p a c t o n p a o u tc o m e m e a s u re s c h ri s ti a n s e n e t a l. ( 2 0 1 5 )2 9 r a n d o m iz e d c o n tr o lle d t ri a l w e e k ly t e le p h o n e s e s s io n , la s ti n g 1 2 w e e k s . in te rv e n ti o n g ro u p w a s t h e m e d o n h e a lt h b e h a v io u r c h a n g e w h ile t h e c o n tr o l g ro u p w a s t h e m e d o n h e a lt h m o n it o ri n g 1 2 w e e k s 2 4 w e e k s 3 8 n e g a ti v e c o n tr o l 6 3 .5 u n ila te ra l d a ily s te p c o u n t a n d p e rc e n ta g e o f ti m e s p e n t in s e d e n ta ry /l ig h t/ m o d e ra te t o v ig o ro u s a c ti v it ie s s te p c o u n t a n d a c ti v it y i n te n s it y : g t 3 x -b t a n a c c e le ro m e te rb a s e d a c ti v it y m o n it o r b e lt d a ily s te p c o u n t in i n te rv e n ti o n g ro u p w a s s ig n if ic a n tl y h ig h e r th a n c o n tr o l g ro u p a t 1 2 w e e k s a n d a t 2 4 w e e k s . s e d e n ta ry t im e i n in te rv e n ti o n g ro u p n o n -s ig n if ic a n tl y d e c re a s e d c o m p a re d t o c o n tr o l g ro u p a t 1 2 w e e k s b u t s ig n if ic a n tl y d e c re a s e d a t 2 4 w e e k s . l ig h t a n d m o d e ra te /v ig o ro u s t im e s in c re a s e d n o n -s ig n if ic a n tl y i n i n te rv e n ti o n g ro u p c o m p a re d t o c o n tr o l g ro u p a t 1 2 a n d 2 4 w e e k s d e le h a n ty a n d t ra c h s e l (1 9 9 7 )2 8 n o n -r a n d o m iz e d c o n tr o lle d t ri a l 3 w e e k ly , 2 h o u r g ro u p s e s s io n s w h ic h p a rt ic ip a n ts a n d t h e ir f a m ili e s w e re i n v it e d to a tt e n d . t h e y w e re m a d e o f th re e c o m p o n e n ts : re d u c in g d is tr e s s , in c re a s in g re h a b ili ta ti o n p ro g re s s a n d t o e n h a n c e s a ti s fa c ti o n w it h a lo c a l r e h a b ili ta ti o n h o s p it a l p ro g ra m 3 w e e k s 8 m o n th s 4 1 p o s it iv e c o n tr o l 6 1 .4 u n ila te ra l (n = 3 2 ) a n d b ila te ra l (n = 9 ) a c ti v it y l e v e ls f o r s h o p p in g , c h u rc h , b a n k in g , d ri v in g , v a c a ti o n , v is it in g . a c ti v it y l e v e ls a re m e a s u re d i n t e rm s o f h o w o ft e n o r h o w l e s s t h e p a rt ic ip a n t c a rr ie s o u t th e a c ti v it y c o m p a re d t o p re tr a u m a r e h a b ili ta ti o n s u rv e y q u e s ti o n n a ir e s ig n if ic a n t in c re a s e i n a c ti v it y le v e l o n ly f o u n d f o r v a c a ti o n . t h e r e m a in in g a c ti v it ie s h a d n o n -s ig n if ic a n t in c re a s e s i n a c ti v it y l e v e ls k o s m a e t a l. ( 2 0 0 5 )2 0 r a n d o m iz e d c o n tr o lle d t ri a l t re a tm e n t g ro u p r e c e iv e d a 4 -w e e k m o ti v a ti o n a l p ro g ra m . t h e p ro g ra m s e n t le s s o n p la n s f o r th e ir p h y s ic a l a c ti v it y e a c h w e e k v ia e m a il. t h e c o n tr o l g ro u p o n ly r e c e iv e d w e e k ly e n c o u ra g in g m e s s a g e s v ia e -m a il. 1 m o n th 1 m o n th 4 (1 ) n e g a ti v e c o n tr o l 3 8 .7 (3 ) n o t s p e c if ie d l e is u re t im e p h y s ic a l a c ti v it y ( m e t h o u rs /d a y ) p a s ip d n o s ig n if ic a n t d if fe re n c e i n l e is u re t im e p h y s ic a l a c ti v it y w a s f o u n d b e tw e e n c o n tr o l a n d t re a tm e n t g ro u p s . l it tm a n e t a l. ( 2 0 1 9 )3 0 r a n d o m iz e d c o n tr o lle d t ri a l t h e i n te rv e n ti o n g ro u p r e c e iv e d s e lf m o n it o ri n g t o o ls , 1 1 t e le p h o n e c o u n s e lli n g s e s s io n s , a n d 1 p e rs o n a l v is it f ro m a c e rt if ie d p h y s ic a l th e ra p is t, b o th t h e te le p h o n e s e s s io n s a n d p e rs o n a l v is it w e re c e n tr e d o n i m p ro v in g p h y s ic a l a c ti v it y a n d w e ig h t lo s s . t h e c o n tr o l g ro u p r e c e iv e d id e n ti c a l s e lf -m o n it o ri n g t o o ls t o t h e in te rv e n ti o n g ro u p b u t w it h n o p h o n e c a lls o r v is it s f ro m h e a lt h p ro fe s s io n a ls . 2 0 w e e k s 2 0 w e e k s 1 5 n e g a ti v e c o n tr o l 5 6 n o t s p e c if ie d d a ily s te p c o u n t s a m n o s ig n if ic a n t im p ro v e m e n ts i n d a ily s te p c o u n t, h o u rs o f (r e d u c e d ) s e d e n ta ry t im e https://doi.org/10.33137/cpoj.v3i1.33931 14 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj v a n d e r p lo e g e t a l. ( 2 0 0 6 )2 5 c lu s te r r a n d o m iz e d c o n tr o lle d t ri a l o n e i n te rv e n ti o n g ro u p ( r e h a b ili ta ti o n a n d s p o rt ) re c e iv e d a c o u n s e lli n g s e s s io n f ro m a s p o rt s c o u n s e llo r o n g e n e ra l s p o rt s p a rt ic ip a ti o n a d v ic e . t h e o th e r in te rv e n ti o n g ro u p (a c ti v e a ft e r r e h a b ili ta ti o n ) re c e iv e d t h e s e l e s s o n s i n a d d it io n t o p h y s ic a l a c ti v it y c o u n s e llo rle d s e s s io n s , w h ic h d e lv e d f u rt h e r in to t h e i n d iv id u a l, a s s e s s in g p h y s ic a l a c ti v it y s ta tu s , b a rr ie rs t o p h y s ic a l a c ti v it y a n d u s in g p a i n fo rm a ti o n fo ld e rs . t h e c o n tr o ls r e c e iv e d n e it h e r o f th e s e s e s s io n s . m e a n 1 0 3 d a y s f o r r e h a b ili ta ti o n a n d s p o rt i n te rv e n ti o n . m e a n 1 1 7 d a y s f o r r e h a b ili ta ti o n a n d s p o rt + a c ti v e a ft e r r e h a b ili ta ti o n i n te rv e n ti o n m e a n 1 6 6 d a y s f o r r e h a b ili ta ti o n a n d s p o rt i n te rv e n ti o n . m e a n 1 8 0 d a y s f o r r e h a b ili ta ti o n a n d s p o rt + a c ti v e a ft e r r e h a b ili ta ti o n i n te rv e n ti o n 6 4 (2 ) n e g a ti v e c o n tr o l 4 6 .7 (3 ) n o t s p e c if ie d s p o rt p a rt ic ip a ti o n , s p o rt s c o re , m e e ti n g p a re c o m m e n d a ti o n s , l e is u re t im e , h o u s e h o ld a n d w o rk re la te d p h y s ic a l a c ti v it ie s s p o rt p a rt ic ip a ti o n , s p o rt s c o re a n d m e e ti n g p h y s ic a l a c ti v it y r e c o m m e n d a ti o n s : c u s to m q u e s ti o n n a ir e s . l e is u re t im e , h o u s e h o ld a n d w o rk -r e la te d p h y s ic a l a c ti v it ie s : p a s ip d t h e ' r e h a b ili ta ti o n a n d s p o rt ' in te rv e n ti o n h a d n o s ig n if ic a n t e ff e c t o n a n y o f th e f o u r o u tc o m e s . t h e 'a c ti v e a ft e r r e h a b ili ta ti o n ' i n te rv e n ti o n , in c o m b in a ti o n w it h t h e 'r e h a b ili ta ti o n a n d s p o rt ' in te rv e n ti o n , h a d s ig n if ic a n t im p ro v e m e n ts i n s p o rt p a rt ic ip a ti o n a n d a b ili ty t o m e e t p a re q u ir e m e n ts . f o r p a rt ic ip a n ts i n t h e ' o n t re a tm e n t' c a te g o ry , th e c o m b in e d i n te rv e n ti o n a ls o i n c re a s e d s p o rt s c o re . b e rg e e t a l. (2 0 0 5 )3 9 c ro s s o v e r t ri a l c ro s s o v e r c o m p a ri s o n o f s h o c k -a b s o rb in g p y lo n a n d r ig id p y lo n p ro s th e ti c d e s ig n s 8 w e e k s 4 w e e k s 1 5 p o s it iv e c o n tr o l 5 1 u n ila te ra l (n = 1 5 ) w e e k ly s te p c o u n t s a m n o s ig n if ic a n t d if fe re n c e s i n w e e k ly s te p c o u n t b e tw e e n th e t w o t y p e s o f p y lo n d e s ig n b u is e t a l. ( 2 0 1 4 )3 1 r a n d o m iz e d c o n tr o lle d t ri a l s u b je c ts r e c e iv e d e it h e r a t o ta l s u rf a c e b e a ri n g s o c k e t o r a p a te lla r t e n d o n -b e a ri n g s o c k e t a n d h a d th e ir p h y s ic a l a c ti v it y p ro fi le s m e a s u re d . 6 d a y s 6 d a y s 4 8 p o s it iv e c o n tr o l 5 5 u n ila te ra l (n = 4 8 ) c a d e n c e , d a ily s te p c o u n t a c ti v p a l n o s ig n if ic a n t d if fe re n c e s i n d a ily s te p p in g a c ti v it y , a n d c a d e n c e s th ro u g h o u t th e d a y w e re s im ila r b e tw e e n b o th g ro u p s c o le m a n e t a l. ( 2 0 0 4 )3 8 c ro s s o v e r tr ia l c ro s s o v e r c o m p a ri s o n o f e la s to m e ri c g e l l in e r a n d p o ly e th y le n e f o a m l in e r 2 6 w e e k s ( 6 m o ) 1 3 w e e k s ( 3 m o ) 1 3 p o s it iv e c o n tr o l 4 9 u n ila te ra l (n = 1 3 ) s te p a c ti v it y , w e a r ti m e o f p ro s th e s is s a m s te p a c ti v it y w a s s ig n if ic a n tl y im p ro v e d i n t h e p o ly e th y le n e lin e r s y s te m , in t e rm s o f h o w m a n y s te p s w e re t a k e n p e r d a y , th e n u m b e r o f in a c ti v e h o u rs p e r d a y a n d t h e n u m b e r o f m in u te s o f m o d e ra te o r h ig h a c ti v it y . t h e in te n s it y d is tr ib u ti o n o f a c ti v e ti m e d id n o t c h a n g e . t h e p o ly e th y le n e s o c k e t w a s a ls o w o rn f o r m o re h o u rs i n t h e d a y h a fn e r e t a l. ( 2 0 0 7 )3 7 c o n tr o lle d r e v e rs a l (a -b -a -b ) tr ia l c o n tr o lle d r e v e rs e d c o m p a ri s o n o f m e c h a n ic a l c o n tr o l a n d m ic ro p ro c e s s o r c o n tr o l p ro s th e ti c k n e e 3 5 -6 6 w e e k s ( d e p e n d e n t o n a c c lim a ti o n f o r m ic ro p ro c e s s o r k n e e ) 8 w e e k s 1 7 p o s it iv e c o n tr o l 4 8 u n ila te ra l (n = 1 7 ) d a ily s te p c o u n t a n d e s ti m a te d d a ily s te p d is ta n c e s a m t h e re w e re n o s ig n if ic a n t d if fe re n c e s i n d a ily s te p a c ti v it y o r d a ily d is ta n c e b e tw e e n t h e t w o ty p e s o f p ro s th e ti c k n e e a t a n y s ta g e i n t h e i n te rv e n ti o n . w it h in e a c h i n te rv e n ti o n , th e s te p a c ti v it y d e c re a s e d n o n -s ig n if ic a n tl y a ft e r th e i n it ia l s e t o f m e a s u re m e n ts w it h b o th t y p e s o f k n e e . k a u fm a n e t a l. (2 0 0 8 )3 3 c ro s s o v e r tr ia l c ro s s o v e r c o m p a ri s o n o f m e c h a n ic a l c o n tr o l a n d m ic ro p ro c e s s o r c o n tr o l p ro s th e ti c k n e e s a p p ro x im a te ly 3 8 w e e k s o n a v e ra g e (1 8 -w e e k a c c lim a ti o n fo llo w e d b y 1 0 -d a y te s ti n g p e r k n e e ) 1 8 w e e k s 1 5 p o s it iv e c o n tr o l 4 2 u n ila te ra l (n = 1 5 ) d a ily e n e rg y e x p e n d it u re d o u b ly l a b e lle d w a te r m e th o d m ic ro p ro c e s s o r k n e e s h a d s ig n if ic a n tl y h ig h e r d a ily e n e rg y e x p e n d it u re https://doi.org/10.33137/cpoj.v3i1.33931 15 jamieson a.g, murray l, buis a. the use of physical activity outcomes in rehabilitation interventions for lower limb amputees: a systematic review. canadian prosthetics & orthotics journal. 2020;volume3, issue1, no.2. https://doi.org/10.33137/cpoj.v3i1.33931 issn: 2561-987x the use of physical activity outcomes in rehabilitation jamieson et al. 2020 cpoj k lu te e t a l. (2 0 0 6 ) [a ]2 7 c ro s s o v e r tr ia l c ro s s o v e r c o m p a ri s o n o f s h o c k a b s o rb in g p y lo n a n d r ig id p y lo n 8 w e e k s 4 w e e k s 1 5 p o s it iv e c o n tr o l 5 4 u n ila te ra l t ra n s ti b ia l (n = 1 5 ) d a ily s te p c o u n t a n d d u ra ti o n o f a c ti v it y (m in u te s p e r d a y ) s a m p y lo n d e s ig n h a d n o im p a c t o n a c ti v it y le v e ls k lu te e t a l. (2 0 0 6 ) [b ]2 7 c ro s s o v e r tr ia l c ro s s o v e r c o m p a ri s o n o f m e c h a n ic a l c o n tr o l a n d m ic ro p ro c e s s o r c o n tr o l p ro s th e ti c k n e e 2 6 w e e k s ( 6 m o ) 1 3 w e e k s ( 3 m o ) 5 p o s it iv e c o n tr o l 4 8 u n ila te ra l t ra n s fe m o ra l (n = 5 ) d a ily s te p c o u n t a n d d u ra ti o n o f a c ti v it y (m in u te s p e r d a y ) s a m k n e e d e s ig n h a d n o im p a c t o n a c ti v it y le v e ls k lu te e t a l. (2 0 1 1 )3 6 c ro s s o v e r tr ia l c ro s s o v e r c o m p a ri s o n o f v a c u u m -a s s is te d s o c k e t s u s p e n s io n a n d p in s u s p e n s io n 8 w e e k s 4 w e e k s 5 p o s it iv e c o n tr o l 5 6 u n ila te ra l (n = 5 ) w e e k ly s te p c o u n t s a m s te p a c ti v it y w a s s ig n if ic a n tl y l e s s w h e n s u b je c ts w o re t h e v a c u u m a s s is te d s o c k e t s u s p e n s io n s y s te m c o m p a re d t o th e p in s y s te m m o rg a n e t a l. (2 0 1 8 )8 c ro s s o v e r tr ia l c ro s s o v e r c o m p a ri s o n o f e n e rg y -s to ri n g p ro s th e ti c f e e t a n d c ro s s o v e r p ro s th e ti c f e e t 8 w e e k s ( 2 m o ) 4 w e e k s ( 1 m o ) 2 7 p o s it iv e c o n tr o l 4 2 u n ila te ra l (n = 2 7 ) d a ily s te p c o u n t s a m n o s ig n if ic a n t d if fe re n c e i n d a ily s te p p in g a c ti v it y b e tw e e n t h e t w o ty p e s o f p ro s th e ti c fe e t s e g a l e t a l. ( 2 0 1 4 )3 5 c ro s s o v e r tr ia l c ro s s o v e r c o m p a ri s o n o f t o rs io n a d a p te r a n d r ig id a d a p te r 8 w e e k s ( 2 m o ) 4 w e e k s ( 1 m o ) 1 0 p o s it iv e c o n tr o l 5 6 u n ila te ra l (n = 1 0 ) d a ily s te p c o u n t, i n te n s it y o f s te p s ( m e a s u re d i n s tr id e s /m in ) s a m d a ily s te p c o u n t w a s n o n s ig n if ic a n t b e tw e e n t h e t w o ty p e s o f a d a p te r. h o w e v e r, lo w a n d m e d iu m i n te n s it y s tr id e s w e re s ig n if ic a n tl y h ig h e r in t h e t o rs io n a d a p te r. h ig h i n te n s it y s tr id e s w e re n o n -s ig n if ic a n tl y d if fe re n t, a n d a c tu a lly l o w e r in t h e t o rs io n a d a p te r. s e lle s e t a l. ( 2 0 0 5 )3 2 r a n d o m iz e d c o n tr o l tr ia l t h e i n te rv e n ti o n g ro u p re c e iv e d a t o ta l s u rf a c e b e a ri n g s o c k e t, w h ile t h e c o n tr o l g ro u p r e c e iv e d a p a te lla r te n d o n -b e a ri n g s o c k e t. a ft e r 3 m o n th s o f a c c lim a ti o n , p h y s ic a l a c ti v it y d a ta o v e r a 2 4 h p e ri o d w a s c o lle c te d . 1 2 w e e k s ( 3 m o ) 1 2 w e e k s ( 3 m o ) 2 6 p o s it iv e c o n tr o l 6 3 u n ila te ra l (n = 2 6 ) t im e s p e n t in d y n a m ic a c ti v it ie s , n o . o f b o d y p o s tu re tr a n s it io n s , m o ti lit y a c ti v it y m o n it o r n o s ig n if ic a n t d if fe re n c e i n a n y a c ti v it y m e a s u re m e n ts b e tw e e n t h e t w o s o c k e t d e s ig n s a n d b e tw e e n b a s e lin e a n d f o llo w u p f o r e a c h d e s ig n t h e e v e n e t a l. ( 2 0 1 2 )3 4 c ro s s o v e r tr ia l c ro s s o v e r c o m p a ri s o n o f m ic ro p ro c e s s o r k n e e w it h c o n tr o l o f s ta n c e a n d s w in g p h a s e a n d m ic ro p ro c e s s o r k n e e w it h c o n tr o l o f s ta n c e p h a s e o n ly , w it h a d d it io n a l c o m p a ri s o n to m e c h a n ic a l k n e e c o n tr o l 2 w e e k s 1 w e e k 3 0 p o s it iv e c o n tr o l 5 9 u n ila te ra l (n = 3 0 ) a c ti v it y l e v e l (c o u n ts /d a y ), a m o u n t o f a c ti v e t im e , m e a n n o . o f b o u ts o f a c ti v it y /d a y a c ti g ra p h a c ti v it y l e v e l d e c re a s e d i n m ic ro p ro c e s s o r k n e e c o m p a re d to m e c h a n ic a l k n e e i n t h e "i n te rm e d ia te " s u b -g ro u p . n o . o f b o u ts o f a c ti v it y p e r d a y d id n o t c h a n g e b e tw e e n t h e t w o t y p e s o f m ic ro p ro c e s s o r k n e e a n d t h e m e c h a n ic a l k n e e . https://doi.org/10.33137/cpoj.v3i1.33931 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.36210 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 stakeholder perspectives health service delivery and economic evaluation of limb lower boneanchored prostheses: a summary of the queensland artificial limb service’s experience berg d1, frossard l2-5 * 1 queensland artificial limb service, brisbane, australia. 2 yourresearchproject pty ltd, brisbane, australia. 3 griffith university, gold coast, australia. 4 university of the sunshine coast, maroochydore, australia. 5 queensland university of technology, brisbane, australia. introduction my name is debra berg. for over 20 years, i have been the manager of queensland artificial limb service (qals), a queensland health organization delivering artificial limbs to individuals suffering from limb loss. my principal mandate as manager of state service is to support the best possible prosthetic care while ensuring accountability for the use of taxpayer dollars. initial awareness i became aware that osseointegration could provide opportunities for direct skeletal prosthetic attachment in the early 1990s, when the first cases were presented at various international conferences by dr. rickard branemark, a leading surgeon from the sahlgrenska university hospital, gothenburg, sweden.1-3 similar to the rest of the prosthetic care community, i recognized the potential capacity of this surgical procedure to alleviate caveats of socket-suspended prostheses (ssps).4 however, it was unclear how contraindications for consumers experiencing vascular problems and the inevitable adverse events (e.g., infections) that could lead to removal of the implant and reamputation should be dealt with.5 open access volume 4, issue 2, article no.12. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract the emergence of skeletal prosthetic attachments leaves governmental organizations facing the challenge of implementing equitable policies that support the provision of bone-anchored prostheses (baps). in 2013, the queensland artificial limb service (qals) started a five-year research project focusing on health service delivery and economic evaluation of baps. this paper reflects on the qals experience, particularly the lessons learned. qals’ jurisdiction and drivers are presented first, followed by the impact of outcomes, barriers, and facilitators, as well as future developments of this work. the 21 publications produced during this project (e.g., reimbursement policy, role of prosthetists, continuous improvement procedure, quality of life, preliminary costutilities) were summarized. literature on past, current, and upcoming developments of bap was reviewed to discuss the practical implications of this work. a primary outcome of this project was a policy developed by qals supporting up to 22 h of labor for the provision of bap care. the indicative incremental cost-utility ratio for transfemoral and transtibial baps was approximately aud$17,000 and aud$12,000, respectively, per quality-adjusted life-year compared to socket prostheses. this project was challenged by 17 barriers (e.g., limited resources, inconsistency of care pathways, design of preliminary cost-utility analyses) but eased by 18 facilitators (e.g., action research plan, customized database, use of free repositories). in conclusion, we concluded that lower limb bap might be an acceptable alternative to socket prostheses from an australian government prosthetic care perspective. hopefully, this work will inform promoters of prosthetic innovations committed to making bionic solutions widely accessible to a growing population of individuals suffering from limb loss worldwide. citation berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 keywords artificial limbs, bionics, bone-anchored prosthesis, cost-effectiveness, costutility, health economic evaluation, health service delivery, osseointegration * corresponding author laurent frossard (phd), professor of bionics, yourresearchproject pty ltd, brisbane, australia. e-mail: laurentfrossard@outlook.com orcid number: https://orcid.org/0000-0002-0248-9589 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.36210 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.36210 mailto:laurentfrossard@outlook.com https://orcid.org/0000-0002-0248-9589 2 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e regardless, it was clear that the progress of this new treatment was remarkable and truly worth monitoring. osseointegration was systematically included in qals’ regular horizon scans of prosthetic care innovations having potential to alleviate the clinical and financial burdens of prosthetic attachment for queenslanders (e.g., review of literature about efficacy and safety). a handful of patients were first fitted with a screw-type implant in 2000 by a team in melbourne, victoria, in collaboration with the pioneering group in sweden.6 curious to know more, i invited dr. kerstin hagberg, an acclaimed rehabilitation specialist from sahlgrenska university hospital, to give a talk on her osseointegrated prostheses for the rehabilitation of amputees (opra) study for consumers, clinicians, and healthcare administrators in brisbane, queensland, in 2005.2,7,8 this presentation gave us a better understanding of the rehabilitation program as well as the benefits (e.g., improvement in health-related quality of life, prosthetic use, embodiment, prosthetic knee and hip range of motion, sitting comfort, donning and doffing, osseoperception, walking ability) and harms of osseointegration (e.g., skin irritation around the stoma, loosening, periprosthetic fractures, mechanical failure of implant parts, deep and superficial infections, removal).1,7,9 it also highlighted that bone-anchored prostheses (baps) could lessen expenditure from socket fittings and residuumrelated skin treatments.4 this was the first time i wondered how the emergence of new treatments relying on direct skeletal attachment and the subsequent provision of bap could impact the day-to-day work of a governmental organization such as qals. challenges answering this question became critical when the first queenslanders with unilateral transfemoral amputation were treated interstate in late 2012. initially, we dealt with these consumers on a case-by-case basis. this approach was required to understand and address immediate needs. however, it created too much uncertainty and unpredictability to be sustainable. furthermore, we anticipated a significant influx of consumers in the short term. soon after, qals faced the challenge of putting in place a procedure to warrant a fair and equitable delivery of lower limb bap to its consumers. needs as an administrator, and often gatekeeper of taxpayers’ money, i considered it essential to make decisions about a new treatment based on the best clinical and socioeconomic evidence available. prosthetic care must be supported but resources are limited. like many other managers of government healthcare organizations, every dollar spent by qals must be spent according to “financial marching orders” (e.g., schedule of allowable expenses). literature searches conducted during horizon scans and discussions with colleagues revealed that there was limited information about the alleged socioeconomic advantages of bap.10,11 clearly, there was a knowledge gap: what could the provision of bap mean for government healthcare organizations in terms of service delivery and expenditures? in 2013, i initiated what turned out to be a five-year project of research gathering evidence to support the provision of bap from the qals perspective (figure 1). we assessed the areas of disruptions while trying to find ways to accommodate new expectations. this project examined changes related to the service delivery of bap, including the development of a policy supporting the provision of bap, the role of prosthetists, adjustments of continuous improvement procedures, and consumers’ quality of life. this project also involved a health economic evaluation of transfemoral and transtibial baps, including cost comparison and preliminary cost-utility analyses (cuas), compared to ssp. purposes this paper reflects on the qals experience gained during this research project. the main purpose was to summarize the outcomes from a bird’s-eye view. we have shared the lessons learned during our journey through hands-on information that might be helpful for all bap promoters, including end users and carers, providers of prosthetic solutions, and administrators of healthcare organizations, amongst others. the specific objectives were to: • introduce some background information about qals’ jurisdiction to facilitate cross-comparison and transferability of our experience • outline the drivers that motivated this work list of abbreviations bap: bone-anchored prostheses cqi: continuous quality improvement cua: cost-utility analysis esar: energy storing and return feet hee: health economic evaluation icur: incremental cost-utility ratio k: medicare functional classification level mpk: microprocessor-controlled knee qaly: quality-adjusted life-year sf36: 36-item short form survey ssp: sockets-suspended prostheses wtp: willingness-to-pay threshold https://doi.org/10.33137/cpoj.v4i2.36210 3 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e • present an overview of the impacts and outcomes • share the selected barriers and facilitators met during this project separately, although they were intertwined and • suggest briefly future developments of this work alongside some calls to action to further promote innovations in the service delivery and economic evaluation of bap drivers, barriers, and facilitators we deemed within and beyond qals’ influence were highlighted so that other organizations could identify their internal strengths and possible external threats during the strategic planning of similar research projects (e.g., strengths, weaknesses, opportunities, and threats analysis). supplementary materials to be published in a data in brief paper provided additional information about the qals’ jurisdiction, publications (e.g., distribution, breakdown of impacts, downloads worldwide), allowable hours for prosthetist’s labor (e.g., phases of treatment, tasks), study cohorts (e.g., sample size, representativeness), and datasets considered to estimate costs (e.g., number of claims, prediction), as well as detailed descriptions of all barriers and facilitators. jurisdiction qals is in the jurisdiction of the queensland state government minister of health, one of the six states and three territories of australia. the role of qals is to ensure equitable provision and funding of external prosthetic components to eligible residents of queensland. eligible consumers must be registered with the qals and (1) be eligible for definitive prosthetic funding support under the queensland government’s “artificial limb scheme” or (2) be eligible under the rehabilitation appliance program of the department of veteran affairs. qals has a yearly budget of aud$5.4 million to provide prosthetic services to 3,600 active consumers annually through a network of up to 10 individual prosthetists (e.g., cpo). although queensland has predominantly an urban population, qals services consumers across the whole state. queensland has hot and humid weather for the most part of the year. these conditions make the typical ssp difficult to tolerate and increase the need for frequent socket fittings. access to the closest point of care can be particularly critical for some consumers who might have to travel hundreds of kilometers to visit their prosthetist for socket and component fittings. altogether, the prospect of socket-free prosthetic solutions could be particularly appealing for qals consumers. continuous quality improvement role of prosthetists policy for provision health service delivery tta preliminary cost-utility costcomparison health economic evaluation qals’ project of research about provision of bap tf preliminary cost-utility costcomparis tfa preliminary cost-utility costcomparison consumer’s quality of life figure 1: overview of the research project focusing health service delivery and health economic evaluations of transfemoral (tfa) and transtibial (tta) bone-anchored prostheses (baps) led by the queensland artificial limb service (qals). https://doi.org/10.33137/cpoj.v4i2.36210 4 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e currently, qals is looking after a case-mix of nearly 100 consumers using unilateral, bilateral, and quadrilateral baps, representing approximately 11% and 6% of the existing population using bap which is estimated at 950 in australia and 1,600 worldwide, respectively. the number of qals consumers has increased steadily by up to 10 per year over the last three years, generating one of the largest growing populations worldwide. drivers beyond our initial genuine interest in the economic impacts of the provision of bap, this research project was pragmatically motivated by a series of external and internal drivers to the organization. external drivers as hinted at in the historical introduction, this project emerged because of external drivers, including, but not limited to, the following: • a growing number of consumers. in 2012, qals started to experience a significant influx of existing and new consumers choosing direct skeletal attachments. projections estimated that the number of consumers choosing bap will continue to increase noticeably, possibly reaching between 150 and 200 consumers by 2025. • prosthetists’ concerns. this project was also required to adequately recognize the hours spent by prosthetic care providers looking after consumers with bap that should be supported by qals. in 2012, there were no items within the existing qals’ schedules of allowable hours that prosthetists could claim after they provided standard care to fit bap (e.g., no set hours for a specific service). the pathways for the compensation of their services were unclear. providers could potentially experience improper compensation for fitting the bap and loss of revenues from socket fittings. internal drivers this research project was also needed from several qals organizational standpoints, including, but not limited to, the need to: • apply evidence-based practice. like other government organizations, qals was required to provide evidence s c ie n ti fi c r e c o g n it io n downloads +6,500 views +13,600 citations 95 p u b lic a ti o n o u tp u t articles 10 publications 21 abstracts 9 in te rn a ti o n a l a c k n o w le d g e m e n ts read 70 countries presented 2 countries used +5 jurisdictions p u b lic a ti o n o u tp u t publications 21 figure 2: key indicators of the overall scientific impact of the research project (e.g., publication output, scientific recognition, international acknowledgments) focusing on the health service delivery and health economic evaluation of limb lower bone-anchored prostheses lead by the queensland artificial limb service between 2015 and 2020. https://doi.org/10.33137/cpoj.v4i2.36210 5 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e supporting decisions about reimbursement standards, particularly for the provision of new health technology innovations that could be costly and obsolete within five years.12 • manage stakeholders’ expectations. clarification of the processes for service delivery of bap was required to manage expectations from qals stakeholders, including consumers and prosthetic care providers. consideration whether the proposed procedures had legal bearings might be irrelevant (e.g., unlikelihood of lawsuits). regardless, qals believed that outlying these processes should help mitigate potential misunderstandings and conflicts inherent to the implementation of a new and, possibly, risky treatment. • verify cost-saving potential. economic evaluations were required to confirm and, more importantly, to quantify if taxpayers’ money could be saved with the provision of bap, reducing the costs of socket fittings. understanding cost-saving was essential to facilitate implementation given the budget constraints. • assist strategic planning. one of the most critical drivers was to gather sufficient information to complete the qals’ five-year strategic business plan, including yearly budgets for the provision of prosthetic care stratified by case-mix, including those with bap. it was anticipated that the outcomes of this project would assist qals with predictable workflow, help manage resources, and ultimately plan a realistic budget. • take leadership. perhaps less pragmatic but equally important was qals’ aspiration to take a leadership role in the area of health economic research on prosthetic osseointegration solutions that was then overlooked. impact overview the overall impact of the project was summarized by nine key indicators which are presented in figure 2 reflecting the publication outputs, scientific recognitions, and international acknowledgments. publication outputs to date, we have authored a series of 21 publications between 2015 and 2020 (e.g., digital object identifier, international standard book number), including six (48%) original research papers, one (5%) dataset paper, three (14%) repository papers, nine (43%) abstracts in national and international conferences, and two (10%) scientific annual reports.13-33 only manuscripts published or in press were considered here. however, several manuscripts are currently in preparation for submission to health economics and prosthetic care journals as well as open access repositories (e.g., data in brief). scientific recognitions the recognition of each publication was assessed using conventional bibliometrics and altmetrics, including the number of views, downloads, and citations extracted from research institutions’ repositories, social network sites for scientists, publishers’ websites, and citation databases. to date, these publications have accumulated approximately 13,600 views, 6,500 downloads, and 95 citations, as detailed in table 1. citations of the three papers were in the 46th, 71st, and 46th percentiles corresponding to average, good, and above-average attention scores compared to other papers of a similar age in all journals, according to pharmacoeconomics-open, journal of prosthetics and items views(1) download(1) citations(1) (#) (%) (#) (%) (#) (%) (#) (%) total publications 21 100 13,666 100 6,543 100 95 100 total papers 10 48 9,859 72 5,298 81 94 99 original papers (2) 6 29 9,638 71 5,144 79 91 96 dataset papers (3) 1 5 221 2 154 2 3 3 repository papers (4) 3 14 0 0 0 0 0 0 total abstracts 9 43 2,930 21 841 13 0 0 international conference (5) 1 5 243 2 62 1 0 0 national conference (6) 8 38 2,687 20 779 12 0 0 total reports 2 10 877 6 404 6 1 1 (1) extracted from research institutions’ free-access repositories (i.e., queensland university of technology’s eprint, university of the sunshine coast’s research banks, griffith university research online), social networks sites for scientists (i.e., researchgate, mendeley), publishers’ websites (i.e., canadian prosthetics & orthotics journal, data in brief, journal of prosthetics and orthotics, pharmacoeconomics-open, prosthetics and orthotics international) and citation databases (i.e., google scholar, elsevier's scopus); (2) published in canadian prosthetics & orthotics journal, journal of prosthetics and orthotics, pharmacoeconomics-open, prosthetics and orthotics international, the aopa revie; (3) published in data in brief; (4) published in mendeley; (5) presented at international society of prosthetics and orthotics; (6) presented at australasian osseointegrated for amputees conference table 1: number and percentage of views, downloads, and citations of each type of publication focusing on the health service delivery and health economic evaluation of limb lower bone-anchored prostheses produced by the queensland artificial limb service (qals) between 2015 and 2020. https://doi.org/10.33137/cpoj.v4i2.36210 6 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e orthotics, and prosthetics and orthotics international, respectively.14,16 international acknowledgments analyses of eprint records indicated that publications were downloaded from approximately 70 countries, with 75% of the downloads made from australia (32%), united states of america (30%), canada (6%), united kingdom of great britain and northern ireland (4%), and ireland (3%). more importantly, these publications were considered and often cited in recent health technology assessments of osseointegrated prosthetic solutions produced by several government organizations (e.g., australian states, canadian provinces, united kingdom, new zealand, spain).34-40 this work provided guidance when the australian national disability insurance scheme developed its funding model. contributions the actual developments of each topic of research progressed altogether and often organically, depending on opportunities and resources. therefore, contributions are presented by topics rather than historical evolution. health service delivery our primary contribution was the development of a policy regulating the provision of bap-specific prosthetic care. effectively, these procedures organized a workflow meshing role for prosthetists, a quality improvement of specific procedures, and assessment of overall consumers’ experience and quality of life. policy for provision of bap in 2012, information from health technology assessments of direct skeletal attachment that could help develop this policy was sparse.10,11,41-44 consequently, we conducted an action research study involving the first 18 qals consumers between january 2011 and june 2015 to create qals policy for the provision of transfemoral bap.14,23,28 an initial version of this policy was published in 2017 (e.g., tasks, documents, costs), including possible obstacles and facilitators to implementation.14 an equitable provision of transfemoral bap was based on seven processes involving fixed expenses during the treatment and five processes regulating ongoing prosthetic care expenses. the cornerstone of this policy was the allowance of 22 h toward prosthetist’s labor to support delivery of bap care costing up to aud$3,300 per consumer. a prosthetist could spend 2.5 h (11%), 2.5 h (11%), 6.5 h (30%), and 10.5 h (48%) during the preoperative, surgical, fitting of light and definitive limb prostheses, and postoperative phases of the treatment, respectively. this policy required adjustments related to the prosthetists’ scope of practice, funding of prosthetic limbs during rehabilitation, and allocation of microprocessor-controlled prosthetic knees. role of prosthetists early investigations revealed that the role of prosthetists in the provision of bap has been largely overlooked, although they are at the heart of treatment (e.g., primary point of contact for consumers, responsible for prosthetic loading).10,17,42 in the policy presented earlier, prosthetists could claim up to 22 h of labor including 4 h (18%), 2 h (9%), 14 h (64%), and 2 h (9%) to consult with the clinical team, evaluate functional outcomes, fit light and definitive prostheses, and report progress to stakeholders before and after the surgical implantation of the osseointegrated fixation, respectively.14 as summarized in figure 3, frossard et al. (2018) further detailed the critical roles prosthetists could play during the provision of bap, including referral of consumers (e.g., discussing fitting options, elucidating surgical procedures, selecting the surgical team).17 the survey presented by frossard et al. (2019) indicated that 25% of qals consumers found information about the surgical procedure from a prosthetist.20 as expected, prosthetists should be responsible for usual fitting tasks (e.g., selection of components, alignment of prosthesis, prevention of falls). however, as reported in clark (2021), prosthetists also play a key role in the prevention of load-related adverse events when fitting bone-anchored bionics prostheses.45 fittings of bap must be made with additional constraints to limit unwanted loads, leading to increased risks for the boneimplant interface (e.g., loosening, breakage of connector and safety device, periprosthetic fractures, infection, removal).46-50 altogether, this study showed that the provision of bap has the potential to be slightly outside the usual scope of practice of prosthetists.51 training opportunities by qualified experts, guidelines from suppliers of implants, and formal recommendations from governing bodies about prosthetic care of consumers fitted with bap and business management that could help reduce risks are sparse, or even missing, in some jurisdictions. prosthetists may potentially be exposed to increased risks when treating bap consumers.17 quality improvement procedure the implementation of the qals policy for the provision of transfemoral bap has subsequently created a need for a continuous quality improvement (cqi) procedure seeking to enhance consumers’ experience with the qals process, supporting the provision of bap. https://doi.org/10.33137/cpoj.v4i2.36210 7 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e figure 3: roles, actions and focus of prosthetic care provided by prosthetists to consumers fitted with transfemoral and transtibial boneanchored prostheses at various stages of treatment (e.g., pre-op, surgery, post-op, on-going) included tasks supported by queensland artificial limb service (qals) and tasks of the fringe of usual scope of practice of prosthetists. adapted from frossard et al (2018).17 pre-op definitive prosthesis manage bone/implant coupling select consumer r o le f o c u s on-going surgeries rehabilitation prosthesis post-op provide prosthetic care a c ti o n action supported by qals refer fall periprosthetic fractures component breakage under loading over loading removal superficial/deep infection infections eligibility implant placement understand residuum configuration screen report consult report fit assess report service assess report prevent monitor address loosening action at the fringe of scope of practice action supported by qals https://doi.org/10.33137/cpoj.v4i2.36210 8 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e frossard et al. (2018) presented a bap-inclusive cqi procedure.17,32 a redesign study led to this procedure to collect, analyze, and report the experience of 65 qals consumers who delivered bap-specific prosthetic care, as presented in figure 4. the proposed cqi procedure required 1.3 h of prosthetist labor or 6% of the 22 h allowed for the whole procedure presented above, costing aud$213 per episode of care. the time spent by a prosthetist, consumer, and qals staff represented 24%, 24%, and 53% of the cqi procedure, respectively. the costs of labor for prosthetist and qals staff represented 70% and 30% of the cqi procedure, respectively. this study demonstrated that government organizations can redesign a cqi procedure for comprehensive appraisal of the provision of prostheses that could be: inclusive of bap, affordable and swift for prosthetists. achieving a minimally disruptive bap-inclusive cqi procedure can be facilitated by adaptation of a procedure already in place (e.g., use of routing questions to indicate if the survey is for ssp or bap). consumer’s quality of life another integral part of the cqi procedure was to assess consumers’ experience with the overall provision of bap and changes in their quality of life after implantation of an osseointegrated fixation. frossard et al. (2019) presented the outcomes of a 25question ad hoc survey, including 7 (28%), 5 (20%), and 13 (52%) questions about “osseointegration surgery details,” “pre-osseointegration surgery,” and “post-surgery osseointegration”, respectively.20 a total of 12 out of the 65 eligible qals consumers completed the survey, giving a return rate of 18%. all respondents were “happy” with their bap and indicated that “it works as it should”, including 91% of respondents satisfied with the componentry fitted to their bap. key figures of the respondents’ experience with efficacy and safety of the procedure are provided in table 2. more importantly, all respondents reported a level of satisfaction and quality of life above eight and seven out of 10 after surgical implantation of the osseointegrated fixation and fitting with bap, respectively. these outcomes suggest that qals policy about the provision of bap seemed to contribute favorably to overall consumer satisfaction. altogether, this work provided benchmark information that can educate the design of patients’ experience surveys and clinical trials looking at the effects of bionic solutions on consumers’ quality of life (e.g., built-in governmental cqi procedure). health economic evaluations the qals policy was validated by economic evaluations. basically, this involved looking at cua comparing bap (new interventions) and ssp (usual treatment) using the incremental cost-utility ratio (icur) based on incremental costs, expressed in australian dollars, and utilities, expressed in quality-adjusted life-years (qalys), over time, that could be compared to the willingness-to-pay threshold (wtp) set at aud$40,000 per qaly.16,18,52-55 we purposely chose to perform preliminary cuas, as detailed below, when discussing barriers and facilitators. these analyses were conducted following an initial version of the 15-step iterative process (e.g., feasibility, constructs, analysis, interpretation) presented by frossard et al. (2021).38,39 both preliminary cuas of transfemoral and transtibial baps were performed for a small series of plausible scenarios over a six-year time horizon from the government perspective.16,18 an overview of our approach to collect, extract, and analyze estimates of costs and utilities is presented in figure 5. total costs combined actual and typical costs extracted from financial records and allowable expense schedules, respectively. baseline utilities were extracted from the literature, while incremental utilities were assumed. table 2: key figures about the efficacy and safety of surgical implantation of the osseointegrated fixation and fitting with boneanchored prosthesis (bap) extracted from self-reported ad hoc consumers survey administered by queensland artificial limb service. efficacy safety • respondents wear their bap on average 17±6 hours per day • 91% of respondents said their bap supported their lifestyle needs • 58% of respondents experienced some infections around the exit point of their percutaneous part post-surgery • respondents experience an episode of infections the exit point of their percutaneous part postsurgery for an average of 145±170 days preliminary cost-utility analysis of transfemoral bap frossard et al. (2017) cross-compared historical costs for the provision of ssp with the simulated costs for transfemoral bap (e.g., labor, parts).14 costs were extracted from qals regulatory documentation according to functional levels (e.g., k-levels) and low-cost, budget, and high-cost options for knee and ankle units. the provision of a transfemoral bap was 18% and 79% less than ssp for the prosthetist labor and attachment costs, respectively. bap was more economical by aud$18,200, aud$7,000, and aud$1,600 when fitted with low-cost, budget, and high-cost options, respectively, compared with ssp for the highest functional level (i.e., k4). frossard et al. (2018) reported preliminary cua for a cohort of 16 qals consumers using transfemoral bap (table 3).16 https://doi.org/10.33137/cpoj.v4i2.36210 9 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e the average cost for the provision of transfemoral baps was approximately 40% (aud$13,562±aud$16,497) more than ssp, which can be partially offset by an increase of 0.815 qaly. the provision of a transfemoral bap was costsaving and cost-effective for 19% and 88% of the consumers, respectively. the indicative icur for the provision of a transfemoral bap was approximately aud$17,000 per qaly and significantly below the wtp (figure 6). preliminary cost-utility analysis of transtibial bap frossard et al. (2021) reported a preliminary cua for six qals consumers using transtibial bap (table 3).18 the average cost for the provision of transtibial baps was approximately 20% (aud$5,604 ± aud$12,180) more costly than ssp, which can be offset by an increase of 0.489 qaly. the provision of a transtibial bap was more expensive and cost-saving for 67% and 33% of the participants, respectively. p ro s th e ti c c a re p ro v id e r c o n s u m e r f o rm a c ti o n service evaluation a surgeries post-op light limb pre-op review reimburse enter review enter review enter evaluation c evaluation b pid vos pse invoice acknowledge evaluate evaluate ssp bap ssp bap ssp bap routing question routing question routing question definitive limb figure 4: overview of continuous quality improvement (cqi) procedure seeking to enhance queensland artificial limb service (qals) consumer’ experience with the provision of socket-suspended (ssp) and bone-anchored (bap) prostheses that involved collection of data with prosthetic care providers and consumers (pid: prosthetic issue document, vos: validation of services, pse: prosthetic service evaluation). adapted from frossard et al (2018).17 https://doi.org/10.33137/cpoj.v4i2.36210 10 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e the indicative icur for the provision of a transtibial bap was aud$12,000 per qaly and significantly below the wtp (figure 6). table 3: outcome of preliminary cost-utility analyses providing indicative incremental cost-utility ratio (icur) based on incremental costs expressed in australian dollars and utilities expressed in quality-adjusted life-years (qaly) for the provision of transfemoral (2016-2017 prices: 1 australian dollar ≈ 0.71 euro ≈ 0.60 british pound ≈ 0.76 us dollar) and transtibial (2018-2019 prices: 1 australian dollar ≈ 0.63 euro ≈ 0.54 british pound ≈ 0.71 us dollar) bone-anchored prosthesis (bap) from queensland artificial limb service (qals) prosthetic care perspective (n: number of consumers).16,18 early evidence of health economic benefits these studies revealed that early engagements with suppliers of prosthetic components particularly suited for transfemoral bap can strongly impact the overall costs (e.g., economical advanced knee and foot/ankle units). these studies also highlighted that suppliers of osseointegrated fixations can influence the outcomes of cua as the cost of their percutaneous parts (e.g., connectors, protective device) could offset the costs of socket fittings. in all cases, the provision of both transfemoral and transtibial baps appeared to be acceptable alternatives to ssp from an australian government prosthetic care perspective. barriers an overview of the 17 main barriers encountered during this project is presented in table 4. a total of 5 barriers (29%) were related to service delivery, 11 (65%) to economic evaluation, and 5 (29%) to project management. a total of 4 and 13 barriers were deemed unlikely (e.g., access to limited resources, dealing with multiple funding allowances, addressing ethics issues, accommodating new national figure 5: overview of the approach applied to conduct preliminary cost-utility analyses (cua) of transfemoral and transtibial bone-anchored (bap) compared to socket-suspended (ssp) prostheses providing incremental cost-utility ratios (icur) based on incremental costs expressed in monetary units and utilities expressed in quality-adjusted life-years (qaly) that were compared to willingness-to-pay threshold (wtp) for small series of plausible scenarios (e.g., base-case, worst-case, best-case) over a six-year time horizon from queensland artificial limb service (qals) prosthetic care perspective.16,18 dataset 1 actual costs dataset 2 typical costs scenario 3 base-case scenario 2 worst-case scenario 1 best-case incremental cost incremental qaly health related quality of life educated choices systematic review literature review cost legislation finance system select consumers icur wtp bap bap bap bap ssp ssp ssp ssp actual + typical increment cost increment utility indicative icur ($/cycle) (qaly/cycle) ($/qaly) transfemoral bap (n=16) mean $13,562 0.815 $16,632 standard deviation $16,497 0.000 $20,231 minimum -$20,933 0.815 -$25,671 maximum $43,625 0.815 $53,499 transtibial bap (n=12) mean $5,604 0.489 $11,453 standard deviation $12,180 0.000 $24,895 minimum -$12,263 0.489 -$25,065 maximum $20,514 0.489 $41,929 https://doi.org/10.33137/cpoj.v4i2.36210 11 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e schemes) and likely (e.g., face inconsistency of care pathways, design preliminary cua, predict timeline of publications) to be met by other government organizations such as qals. here, we have only detailed the core barriers that set in motion cause-and-effect reactions onto other obstacles. access to limited resources as with most prosthetic care departments, resources to undertake a research project of developing evidence-based policy are sparse. unfortunately, we were unable to collaborate with services specialized in health technology assessment within the minister of health. in 2016, we applied for two unsuccessful grants (e.g., defense health foundation grants for medical research, australian centre for health services innovation – implementation grant). supports from other services and funders were curtailed by their perception that the provision of bap was “too niche.” alternatively, the project was to run with qals and its partner resources (e.g., staff time, consultancy). face inconsistency of care pathways another root cause barrier was the unpredictability of bap care pathways corresponding to the onset of a series of interventions made by specialists during the course of treatment. generic descriptions of the surgical procedures and rehabilitation programs specific to either screw-type or press-fit implants published by teams overseas were available when we started.1,2,,6,7,9,56-62 additional ad hoc guidance for specific aspects were provided regularly by main teams in australia as their own procedure evolved organically from case to case. sometimes information from various sources agreed, but they often contradicted themselves. consumers in the same case-mix rarely followed comparable care plans. practically, it was difficult to grasp “who was doing what and when” around the fitting of bap. uncertainty about the continuum of care across preoperative, surgical, and postoperative phases of the treatment created the following barriers: • sort out schedules for allowable expenses. the adequate allocation of allowable hours to support the provision of bap-specific prosthetic care was initially $(40,000) $(30,000) $(20,000) $(10,000) $ $10,000 $20,000 $30,000 $40,000 -1.00 -0.80 -0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00 c o st ( a u d $ ) health gain (qaly) transfemoral bap (n=16) transtibial bap (n=12) wtp quadrant 2: "dominated" quadrant 1: "consider icur" quadrant 3: "consider icur" quadrant 4: "dominant" figure 6: overview of cost-utility analysis showing indicative incremental cost-utility ratio of aud$16,632 and aud$11,453 per qualityadjusted life-year (qaly) and willingness-to-pay threshold (wtp) of aud$40,000 per qaly for transfemoral (2016-2017 prices: 1 australian dollar ≈ 0.71 euro ≈ 0.60 british pound ≈ 0.76 us dollar) and transtibial (2018-2019 prices: 1 australian dollar ≈ 0.63 euro ≈ 0.54 british pound ≈ 0.71 us dollar) bone-anchored prosthesis (bap) that were more costly and more effective than socket-suspended prosthesis (quadrant 1) and below wtp from queensland artificial limb service’s (qals) prosthetic care perspective, respectively (n: number of consumers).16,18 $40,000 $30,000 $20,000 $10,000 $ $10,000 $20,000 $30,000 $40,000 https://doi.org/10.33137/cpoj.v4i2.36210 12 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e complicated by the lack of clarity of overall care pathways. furthermore, providers expressed legitimate concerns about the economic viability of delivering bap, reducing revenue from socket fittings. discussions with clinical teams and prosthetists led to a consensus and subsequent creation of the qals schedule, including 22 allowable h of labor to support bap care. this was only approximately 10 h less compared to the typical 32 h of labor allowed for a socket fitting (i.e., 6 h to cast the residuum, 20 h to build a socket, 6 h to fit a socket).14,17,38,39 however, the loss of income could be compensated by fitting bap with high-end components. • dealing with diversity of outcome measures. accessing clinical outcomes with osseointegrated implants is critical for health economic evaluations (e.g., choice of utility). however, assessing benefits, let alone harms, of surgical treatment was beyond qals’ prerogatives. alternatively, we had to rely on a limited number of outcomes extracted from external sources. choosing relevant outcomes was facilitated by the generic evaluation framework presented in figure 7 which mapped out standardized and nonstandardized instruments for quantitative or qualitative measures of the benefits and harms before and after the fitting of bap used by teams overseas.17,63 ultimately, we preferred health-related quality of life data measured by the standardized 36-item short form survey (sf36) as the primary outcomes to reflect benefits and, more particularly, utility of the treatment.7,57,64 • palliate limited standards of prosthetic care. inconsistent care pathways and diversity in outcome measures, all combined, hinder the understanding of the cause-andeffect relationships between treatment options, benefits, and harms (e.g., two-stage for screw-type, single-stage for press-fit).65,66 this limited the emergence of reasonable standards for bap-specific prosthetic care, let alone the best standards around fitting arrangements that could possibly maximize benefits and minimize exposure to risks (figure 7). however, the evaluation framework raised our awareness about the links between the risks of adverse events and loading regimen depending on the fitting of components as well as daily usage of bap. clearly, the choice of components can play a critical role in reducing loadrelated harms susceptible to osseointegration and the long-term stability of the bone/implant coupling.46,4850,67-69 initially, only a small case series showed differences between loading profiles applied by different categories of components (e.g., basic and advanced knee units).69 we examined mechanically passive components with basic functions such as single-axis or polycentric hydraulic knees and multiaxial foot-ankle units. finally, we acknowledged that the fitting of the microprocessor-controlled knee (mpk) and energystoring-and-return (esar) foot was required. this decision was based on the best evidence available and, more heavily, on the alleged capabilities of these components to increase stability (e.g., stance and swing control), ease of walking (e.g., high range of motion, mechanically powered push-off), attenuate excessive loading (e.g., auto-adaptive stance and swing phases), and reduce falls (e.g., automatic stumble recovery).70 ultimately, we opted to support the provision of a “budget option.” this package combines a single-axis cadence-responsive knee, shock absorption adapter, tube adapter, and a dynamic foot that are commonly provided to qals consumers with the highest functional outcomes (e.g., k4). table 4: list of common and qals barriers related to health service delivery (hsd) and/or health economic evaluation (hee) and/or project management (pm) encountered during research focusing on the provision of lower limb bone-anchored prostheses (bap) led by the queensland artificial limb service (qals). ((s): detailed description to be published in a data in brief). design preliminary cua undertaking preliminary cua came with a range of subsequent obstacles to overcome when choosing the constructs framing the analysis, including, but not limited to, the following: • choosing a relevant perspective. first, we had to choose the perspective of the cua corresponding to the point of view adopted when deciding which healthcare hsd hee pm 1 qals barriers 1-1 access to limited resources x 1-2 deal with multiple funding allowance (s) x 1-3 address ethics issues (s) x x 1-4 new national scheme (s) x number of qals barriers 1 1 3 2 common barriers 2-1 face inconsistency of care pathways x x 2-2 sort out schedules of allowable expenses x x x 2-3 deal with diversity of outcome measures x 2-4 palliate limited standards of prosthetic care x 2-5 choose health economic analysis (s) x 2-6 choose type of cost-utility analysis (s) x 2-7 design preliminary cost-utility analysis x 2-7-1 choose relevant perspective x 2-7-2 establish relevant time horizon x 2-7-3 estimate costs x 2-7-4 access utilities x 2-7-5 estimate weight of assumptions x 2-8 predict timeline of publications (s) x number of common barriers 4 10 2 number of barriers 5 11 5 https://doi.org/10.33137/cpoj.v4i2.36210 13 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e costs should be considered. in principle, a comprehensive analysis could include all surgical, medical, and prosthetic healthcare costs covered by taxpayers. however, queensland state healthcare organizations are structured in such a way that whether the fitting of bap affects medical costs has little impact on the qals’ resources. we were more concerned with the potential reduction in the cost of prosthetic care. therefore, cuas were only conducted from the perspective of government prosthetic care. • establishing a relevant time horizon. the second obstacle was to determine the relevant time horizon corresponding to the time over which outcomes of the innovation should be evaluated.71,72 basu et al. (2019) stated that the time horizon must be long enough to capture the intended and unintended benefits and harms of the intervention.71 o’mahony et al. (2015) indicated that it is often unclear how time influences both the technical adequacy of cost-effectiveness analyses and their correspondence to the policy choices they seek to inform.73 osseointegrated implants are permanent, and fittings of bap are continuous. at first glance, it could make sense to perform a comprehensive cua using markov decision-analytic models to look at multiple scenarios over scalable time horizons (e.g., years, decades, lifetime).44,74-78 however, o’mahony et al. (2015) demonstrated that the approximation error is larger with the long cycle length and that the short cycle cost-effectiveness analyses better approximates the continuous-time reality.73 furthermore, the world health organization recommended the production of generic cost-effectiveness analyses focusing on resources that could realistically be reallocated over the time horizon of the analysis.72 these recommendations lead us to make a compromise of a six-year time horizon, allowing a reasonable prediction of the costs over the components’ life cycle (e.g., two cycles of three years for a foot, three cycles of two years for a knee).16,18 • estimate costs. expenses from the qals financial system for the provision of ssp or bap were unavailable when individuals became qals consumers less than six years before the surgery or when surgery occurred less than six years before the end of the study. as detailed above, the total costs were estimated by blending actual and typical costs. a prediction variable corresponding to relative typical costs over the total costs, expressed as a percentage of the six-year funding cycle, was created to specify the level of uncertainty of the cost estimates. a prediction of 0% and 100% indicated that the total costs were fully extracted from the schedule and financial records, respectively. the overall cost predictions were 48±20% and 46±22% for the provision of transfemoral (ssp, 42±32%; bap, 55±27%) and transtibial (ssp, 43±40%; bap, 49±12%) prostheses, respectively. • access utilities. in principle, utility data may have been obtained from the australian treating teams. however, this option turned out to be impractical (e.g., access limited by ethics, no state-based stratification of datasets) and potentially unreliable (e.g., no clinical trial registration). these issues were resolvable. however, we chose to consider the quality of life status published previously.7,8 baseline qaly were extracted from sf36 datasets converted into qaly applying regression model.[16, 18] we made conservative assumptions to determine the incremental gain of qaly between the ssp and bap fitting options. • estimate the weight of the assumptions. by definition, preliminary cuas overlook comprehensive uncertainty and sensibility analyses. therefore, understanding the impact of assumptions to estimate individual costs (e.g., creation of a schedule of allowable expenses, blending of actual and typical costs) and utilities (e.g., extraction of baseline from literature, assumptions for incremental gain) on both icurs for transfemoral and transtibial baps was limited. the choice of the preliminary cua turned into a facilitator over time. shortcomings might limit the strength of the evidence of cost-utility. however, this decision was critical in delivering the project on budget, on time, and with added value. furthermore, publications of the outcomes contributed to the conversation about the relevance and possibly the standardization of preliminary cuas to assess prosthetic care innovations.38,39,79-81 facilitators an overview of the 18 key facilitators is presented in table 5. a total of 4 (22%) facilitators related to service delivery, 10 (56%) to economic evaluation, and 8 (44%) to project management. a total of 10 facilitators might be specific to qals (e.g., engage with local research teams, involve a critical number of consumers, access to financial data, customize databases, share datasets, use of free repositories). eight facilitators could be transferable to other organizations (e.g., frame action research plan, choose preliminary cua, adapt rather than create procedures, engage with social media, monitor impact). next, we only detailed the facilitators deemed the most critical. customize database qals’ preliminary cuas were facilitated by a piece of software purposely designed to: • import historical data from 1,840 vouchers exported from qals’ financial system for cua of transfemoral https://doi.org/10.33137/cpoj.v4i2.36210 14 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e (i.e., 1,598 vouchers) and transtibial (i.e., 242 vouchers) baps.16,18 • code individual expenses from 4,014 claims to identify whether there were for transfemoral or transtibial prostheses, spp or bap, labor (e.g., fitting prosthesis) or parts (e.g., prosthetic knees and feet units), attachment (e.g., socket, connectors), or prosthesis.16,18 • compare aggregated costs for individuals and groups over the time horizon with ssp and bap before and after surgical intervention, respectively.14,16,18 • create reports including tables and figures formatted for internal communication (e.g., quarterly budget, annual reports) and publications of papers (e.g., manuscript, supplement).14,16,18 this database gave us the flexibility to run queries on demand to present the most up-to-date analyses and outcomes (e.g., new individual expenses to improve predictions). use of free repositories like most government organizations, qals must make the outputs of the project freely available to taxpayers in australia and elsewhere, in a timely manner. we made the point to share original research, datasets, and repository papers including supplements and spreadsheets figure 7: overview of evaluation framework to extract clinical benefits and harms including prosthetic load-related outcomes (sf-36: 36-item short form survey, q-tfa: questionnaire for persons with a transfemoral amputation, ampro: amputee mobility predictor, abc: activitiesspecific balance confidence scale, tug: timed up and go test, 6mwt: 6-minute walk test, gaitrite (cir systems inc, usa), gait laboratory equipment (e.g., 3d motion capture, force plates), ipecslab (rtc electronics, usa), fitbit (fitbit inc, usa)).17,63 residuum integrity infection fixation stability fixation integrity catastrophic failure injuries interview observations interview interview interview interview interview observations observations observations observations observations ipecslab pathology x-rays grading x-rays / mri x-rays / mri x-rays / mri x-rays skin loosening and/or irritation superficial infection deep infection loosening periprosthetic fractures falls breakage implant removal of implant sound limbs mental and physical component summaries prosthetic use, mobility, problem, global amputee mobility predictor score balance duration distance walked characteristics spatial and temporal inner loading usage of prosthesis number of steps, physical activity duration, total energy expended k-level prosthetic use-vm sf-36 q-tfa ampro abc tug 6mwt gaitrite gait lab ipecslab fitbit generic specific health related quality of life mobility prediction stability ambulation abilities walking abilities activity level benefits harms https://doi.org/10.33137/cpoj.v4i2.36210 15 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e as well as abstracts and scientific annual reports available free of cost to the public, either from publishers’ websites, social network sites for scientists, and/or research institution repositories (table 1). availability of publications increased visibility and built up credentials. portals provided a means to monitor the impact (e.g., numbers of views and downloads). in the long run, we hope that access to primary information will encourage collaboration with other promoters of bap and facilitate secondary observational studies (e.g., analyses of causeeffect relationships between confounders and provision of bap) and literature reviews and meta-analyses.40 table 5: list of specific and transferable facilitators related to health service delivery (hsd) and/or health economic evaluations (hee) and/or project management (pm) encountered during research focusing on the provision of lower limb bone-anchored prostheses (bap) led by the queensland artificial limb service (qals). ((s): detailed description to be published in a data in brief) hsd hee pm 1 qals facilitators 1-1 engage with local research teams (s) x 1-2 involve critical number of consumers (s) x x 1-3 access to financial data (s) x 1-4 customize database x 1-4-1 import historical data x 1-4-2 code expenses x 1-4-3 compare costs x 1-4-4 create reports x 1-5 share datasets (s) x 1-6 use of free repositories x number of qals facilitators 1 7 3 2 transferable facilitators 2-1 frame action-research plan x 2-1-1 gather reference group x x x 2-1-2 create stakeholder matrix x 2-1-3 profile case-mix x x 2-2 adapt rather create procedure (s) x 2-3 choose preliminary cua (s) x 2-4 engage with social media (s) x 2-5 monitor impact (s) x number of transferable facilitators 3 3 5 number of facilitators 4 10 8 frame action research plan perhaps more transferable were the lessons learned from the first steps of action research. studies started with the planning phase, including practical tasks to define the project (e.g., identify problems to solve, root cause analysis, define objectives, profile case-mix), determine the deliverables (e.g., review regulatory obligations, conduct stakeholder’s analysis, determine reporting expectations), and review the literature. the following tasks were particularly helpful and transferable: • gathering a reference group or a “think tank” including experts in service delivery, health economics, data analysis, prosthetics and clinical care, biomechanics, and consumer representatives that could, altogether, inform qals management about the relevance and feasibility of research proposals. • creating a stakeholder matrix to organize controllers, promoters, providers, and advocates who can influence the provision of bap (figure 8). the immediate benefit of this exercise was to identify as exhaustively as possible all local, interstate, national, and international stakeholders. this task also required to clearly define the “power” and “interest” of a stakeholder corresponding to its capacity to influence allocation of resources and to provide prosthetic and medical care, respectively. these matrices were most helpful in engaging and managing communication with all stakeholders (e.g., seek funding, present at conferences). • profiling the case-mix involved in a study by presenting the distribution of consumers according to demographics (e.g., sex, age, height, weight, body mass index), amputation (e.g., time since first amputation and bap, cause, level, number of amputations, length of residuum), and access to care (e.g., distance between residence to providers and qals) characteristics. this information was essential to characterize potential confounders and their impact on the provision of bap. for example, knowing the distance between a consumer’s residence and the closest service provider is critical to determine how access to care across a wide state can affect the quality of care. this characterization became valuable when discussing outcomes and writing papers. future work future research will be undertaken in a global environment characterized by: • stronger evidence of efficacy and safety. since this project, the body of peer-reviewed literature focusing on rehabilitation, prosthetic fitting, efficacy, and safety has grown noticeably.3,5,35,65,82-99 several studies justified the prescriptions of mpk and esar components (e.g., goldilocks zone loading).62,100-102 health-related quality of life tend to be reported with a small range of surveys easing cross-comparisons between studies.7,8,57-64 however, there are still no straightforward standardized ways to report harms.48-50 infections are graded using multiple nonstandardized systems.59,65 the risks are yet to be fully satisfactorily resolved.5,65,85,87-89 little is known about long-term outcomes (e.g., influence of aging issues). altogether, it is difficult to ascertain whether direct skeletal prosthetic attachment relying on percutaneous osseointegrated implants will overcome the “decline effect” as described by harris (2016).103 https://doi.org/10.33137/cpoj.v4i2.36210 16 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e • the emergence of global ecosystem. we are also witnessing the formation of a global ecosystem including a set of organizations and services integrating a value chain for the delivery of bap through various commercial models (e.g., consumers and carers, providers of prosthetic solutions, administrators of healthcare organizations).80 the development of this ecosystem is stimulated by strong consumers’ appeal for bap, clearer and more diverse clinical pathways (e.g., indications, distal weight bearing system) and opening the market (e.g., approval from the american food and drug administration).17,100,104,105 however, some funding bodies such as government organizations, private health care, work cover, and insurance are hesitant to fully support the provision of bap requiring stronger evidence from registered clinical trials to test the possible decline effect. figure 8: typical stakeholder matrix including groups of controllers, promoters, providers and advocates of the procedure depending on power (e.g., capacity to influence allocation of resources) and interest (e.g., capacity to provide prosthetic and medical care). adapted from frossard et al (2018).17 future studies could confirm whether the delivery of bap changes the scope of practice (e.g., skills, risks) and business models (e.g., effects on incomes) for all allied health professionals (e.g., prosthetists, physiotherapists, occupational therapists). the outcomes of this preliminary cuas could assist in building plausible scenarios when designing subsequent comprehensive cuas relying on complex bayesian or markov state transition models (e.g., provision of osseointegration options compared to wheelchair, crutches, liners, and ischial containment and subischial sockets).44,72,74-79 more in-depth analyses can be performed from healthcare perspective (e.g. , reimbursement standards) including surgical (e.g., one-off and on-going cost for primary surgical implantation, refashioning of residuum, reamputation, reimplantation), rehabilitation (e.g., physiotherapy), medical (e.g., pain killers, antibiotics), and prosthetic (e.g., socket fittings, interim and definitive prostheses) care costs more holistic cuas could reveal the true costs of infections and subsequent surgical revisions.2,98,99 future studies should also focus on societal perspective (e.g., the impact of bap on employment, productivity, living assistance costs). finally, future studies should also consider consumer perspective, often neglected but equally relevant (e.g., gap fees, out-of-pocket expenses, overseas travelling costs, prosthetic components, medication). conclusion over the last 20 years, i witnessed genuine interest in osseointegration morphing into international momentum, leading to the emergence of a global ecosystem slowly paving the way toward recognition of direct skeletal prosthetic attachments. however, there is a long way ahead before evidence justifies the effective and global adoption of bionic solutions. hopefully, this work will be a valuable contribution. practical information and benchmark figures are provided. we estimated that 24% of the barriers to the project were specific to qals, while 39% of the facilitators were transferable to other organizations. above all, we shared a working approach to justify and organize the provision of prosthetic care for bone-anchored lower limb prostheses from a government perspective. ultimately, we hope this work will inform promoters of prosthetic innovations committed to making bionic solutions widely accessible to a growing population of individuals suffering from limb loss worldwide. call to action • encourage authors of health economic evaluations to make their datasets publicly available (e.g., data in brief) to facilitate secondary observational studies as well as literature reviews and meta-analyses, • inspire decisionmakers responsible of provision of prosthetic care in australia (e.g., national disability insurance scheme) and other jurisdictions worldwide to continue this research work and consolidate evidencebased policies for delivery bone-anchored prostheses and bionic solutions, • motivate national and international stakeholders to establish reference groups working toward collegially agreed procedure (e.g., costs, process) to support reasonable standards of prosthetic care for individuals fitted with bone-anchored prostheses and bionic solutions. acknowledgements the authors wish to express their gratitude to sally cavenett, barry leech, brendan burkett, david lee gow, fiona barnett, ross powrie, gregory merlo, john vasil, luciann ferrada, luke p o w e r l o w h ig h controllers promoters • state governmental funding agencies • national governmental funding agencies • state consumer support groups • national consumer support groups • national professional associations • artificial limbs services in other states • state service providers • national service providers advocates providers low high interest https://doi.org/10.33137/cpoj.v4i2.36210 17 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e lorenzin, stephan laux and tanya quincey for their contribution to the development of this project. declaration of conflicting interests the authors are in the view that there is no competing interests conflicting with the content of this manuscript. sources of support this study was partially funded by the queensland artificial limb service, medical aids subsidy scheme, metro south health, and queensland government minister of health. references 1.hagberg k, brånemark r. consequences of non‐vascular trans‐ femoral amputation: a survey of quality of life, prosthetic use and problems. prosthet orthot int. 2001; 25(3): 186-194. doi: 10.1080/03093640108726601 2.berlin ö, bergh p, dalen m, eriksson s, hagberg k, inerot s, et al. osseointegration in transfemoral amputees: the gothenburg experience. j bone joint surg. 2012; 94-b(supp xiv):55. 3.li y, branemark r. osseointegrated prostheses for 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17(1): 17-25. doi: 10.1080/17434440.2020.1704623 98.wood p, small c, mahoney p. perioperative and early rehabilitation outcomes following osseointegration in uk military amputees. j r army med corps. 2019; p. jramc-2019-001185. doi: 10.1136/jramc-2019-001185 99.matthews dj, arastu m, uden m, sullivan jp, bolsakova k, robinson k, et al. uk trial of the osseointegrated prosthesis for the rehabilitation for amputees: 1995-2018. prosthet orthot int. 2019; 43(1):112-122. doi: 10.1177/0309364618791616 100.opra implant system instructions for use [internet]. 2016; [cited 2021, june 9]. available from: https://www.accessdata.fda.gov/cdrh_docs/pdf8/h080004d.pdf 101.juhnke dl, beck jp, jeyapalina s, aschoff hh. fifteen years of experience with integral-leg-prosthesis: cohort study of artificial limb attachment system. j rehabil res dev. 2015; 52(4): 407-420. doi: 10.1682/jrrd.2014.11.0280 102.niswander w, wang w, baumann ap. characterizing loads at transfemoral osseointegrated implants. med eng phys. 2020; 84:103-114. doi: 10.1016/j.medengphy.2020.08.005 103.cooke dm, ames m, geffen s. life without limbs: technology to the rescue. prosthet orthot int. 2016; 40(4): 517-21. doi: 10.1177/0309364615579316 104.harris i. surgery as placebo: a surgeon cuts through the evidence, ed. n. publishing. 2016; 224. 105.guirao l, samitier b, tibau r, alós j, monago m, moralessuarez-varela m, et al. distance and speed of walking in individuals with trans-femoral amputation fitted with a distal weight-bearing implant. orthop traumatol surg res. 2018; doi: 10.1016/j.otsr.2018.04.011 https://doi.org/10.33137/cpoj.v4i2.36210 https://www.accessdata.fda.gov/cdrh_docs/pdf8/h080004d.pdf 21 berg d, frossard l. health service delivery and economic evaluation of limb lower bone-anchored prostheses: a summary of the queensland artificial limb service’s experience. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.12. https://doi.org/10.33137/cpoj.v4i2.36210 issn: 2561-987x health service delivery and economic evaluation of bone-anchored prostheses berg d. & frossard l., 2021 cpoj special s p e c ia l i s s u e authors scientific biography mrs debra berg is the manager of queensland artificial limb service, queensland health she has over 30 years’ experience in queensland services, including 20 years in delivery of artificial limbs. she is a strong advocate for bone-anchored prostheses in australia for over a decade. mrs berg is acclaimed author of multiple reports and publications looking at the health service delivery and socioeconomics benefits of prosthetic osseointegration for individuals suffering from limb loss. dr laurent frossard is a bionic limbs scientist who is passionate about developing groundbreaking prosthetic solutions to improve the lives of individuals suffering from limb loss. he is internationally recognized as a researcher and an independent expert for his unique expertise in bionic limbs. he approaches bionic solutions from a holistic perspective, by integrating the prosthetic biomechanics, clinical benefits, service delivery, and health economics. dr frossard has over 25 years of experience, both in academia and in private industries in australia, canada, and europe. he has collaborated with over 100 organizations worldwide. he is currently a professor of bionics at the griffith university, the director and chief scientist officer at yourresearchproject pty ltd, and adjunct professor at the queensland university of technology and the university of sunshine coast in australia. https://doi.org/10.33137/cpoj.v4i2.36210 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 1 2024 technical note gholizadeh h, baddour n, dudek n, lemaire e.d. a new temporary training prosthesis for people with transtibial amputation: a technical note. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.2. https://doi.org/10.33137/cpoj.v7i1.43034 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i1.43034 1 gholizadeh h, baddour n, dudek n, lemaire e.d. a new temporary training prosthesis for people with transtibial amputation: a technical note. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.2. https://doi.org/10.33137/cpoj.v7i1.43034 technical note a new temporary training prosthesis for people with transtibial amputation: a technical note gholizadeh h1,2*, baddour n1, dudek n3, lemaire e.d.4,5 1 department of mechanical engineering, university of ottawa, ottawa, canada. 2 ampos orthopaedics inc, ottawa, canada. 3 department of medicine, (division of physical medicine & rehabilitation) and the ottawa hospital, university of ottawa, canada. 4 department of medicine, faculty of medicine, university of ottawa, ottawa, canada. 5 centre for rehabilitation research and development, ottawa hospital research institute, ottawa, canada. introduction limb amputation is a meaningful event that can have both a physical and psychological impact on an individual’s wellbeing. after lower limb amputation, comprehensive rehabilitation is essential for regaining independence, mobility, and enhancing quality of life. before receiving a prosthesis, people with amputation often rely only on wheelchairs or crutches for mobility.1,2 prosthetic fitting typically commences between one to six months after amputation once swelling has subsided and the surgical incision has fully healed. during this phase, while the person is awaiting their prosthesis, a temporary prosthesis may facilitate early ambulation and enable individuals to initiate walking post-amputation.1-3 people with lower limb amputation can utilize a temporary prosthesis within parallel bars or with the assistance of crutches or a cane to enhance residual limb strength and endurance. temporary prostheses or post operative prosthesis can play an important role in the overall success of rehabilitation for people with lower limb amputation, contributing to the prevention of complications associated open access abstract background: while waiting to receive a prosthesis, individuals with amputations could benefit from using a temporary training prosthesis to expedite the rehabilitation process and prepare them for subsequent walking with their prosthesis. objectives: to design and build a temporary training prosthesis for people with a transtibial amputation. methodology: various temporary training prostheses were designed and simulated using solidworks software, followed by fabricating and testing multiple prototypes. initial tests were conducted on five able bodied subjects without amputation to evaluate comfort, ensure the prototype functioned as intended, and to refine the design. the final prototype design had no weight-bearing on the residual limb end and required the person to wear a shrinker or silicone liner. findings: solidworks simulations showed that the device could tolerate up to 200 kg load. subjective feedback indicated that body weight is primarily supported by the thigh section, while partially utilizing the patellar tendon and tibial flares. the thigh section can be shifted 5 cm up or down and 2.5 cm to the front or back from the knee joint center (to enhance knee stability or function). additionally, the thigh angle can be adjusted to 0, 5, 10, or 15 degrees to accommodate hip flexion contracture. the shank section width is adjustable and can be shifted up or down based on the residual limb shape. all five able-bodied participants successfully walked with the non-amputee version of the temporary prosthesis prototype and the device withstood walking, sitting, and standing loads. conclusion: an adjustable temporary training prosthesis was successfully designed, and pilot tested by five able-bodied individuals. future testing will involve five experienced prosthetic users before conducting trials with individuals with a new transtibial amputation. article info received: april 5, 2024 accepted: june 3, 2024 published: june 30, 2024 citation gholizadeh h, baddour n, dudek n, lemaire e.d. a new temporary training prosthesis for people with transtibial amputation: a technical note. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.2. https://doi.org/10.33137/cpoj.v7i 1.43034 keywords amputation, training prosthesis, artificial limb, post-operative prosthesis, prosthetic users, rehabilitation, quality of life, below knee amputation, temporary prosthesis * corresponding author: hossein gholizadeh, phd, cp (canada) department of mechanical engineering, university of ottawa, ottawa, canada. e-mails: hgholizadeh@uottawa.ca, gholizadeh87@yahoo.com orcid id: https://orcid.org/0000-0001-5847-7985 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 1, article no.2. 2024 https://doi.org/10.33137/cpoj.v7i1.43034 https://doi.org/10.33137/cpoj.v7i1.43034 https://doi.org/10.33137/cpoj.v7i1.43034 mailto:hgholizadeh@uottawa.ca mailto:gholizadeh87@yahoo.com https://orcid.org/0000-0001-5847-7985 https://jps.library.utoronto.ca/index.php/cpoj/index 2 gholizadeh h, baddour n, dudek n, lemaire e.d. a new temporary training prosthesis for people with transtibial amputation: a technical note. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.2. https://doi.org/10.33137/cpoj.v7i1.43034 canadian prosthetics & orthotics journal issn: 2561-987x temporary training prosthesis for people with transtibial amputation gholizadeh et.al, 2024 with prolonged bed rest and promoting early discharge from the hospital.2,4-6 very few types of temporary or post operative prostheses are available on the market. in post-amputation rehabilitation, the pneumatic post-amputation mobility aid (ppam) is a device designed to improve balance and gait in individuals with a new lower limb amputation and aid in the reduction of residual limb edema, thereby preparing the residual limb for wearing a prosthesis. however, the device is very bulky, and donning and doffing is not convenient for patients because they require assistance from clinicians, cannot manage the device independently, and cannot use it at home. moreover, patients cannot bend their knee and gait is not symmetrical.7 immediate post-operative rigid dressings with a pylon/foot fitting are also employed in rehabilitation. the concept of rigid dressings was first introduced by muirhead little during the first world war.2 immediate post-operative rigid dressings can promote primary wound healing, facilitate stump shrinkage, prevent knee contracture, and enable early patient mobilization.1,4-6 however, by immobilizing the knee, the rigid dressing obstructs knee joint rehabilitation, resulting in unnatural gait that contradicts rehabilitation goals.8 the bent-knee temporary prosthesis (bktp) is another device designed to pad and offload the residual limb.9 however, a primary concern with bktp and similar devices like the iwalk10 is that the knee is positioned in ninetydegree flexion, which can lead to knee contracture and asymmetric gait. prolonged use of devices like the iwalk can indeed result in significant changes to an individual’s gait, causing asymmetrical walking.10 a simple-to-use, temporary training prosthesis could assist individuals with transtibial amputation in learning how to walk with a prosthesis and remaining active while awaiting to receive their prosthesis. the device should not restrict the knee joint and should be easy to don and doff. additionally, weight distribution between the residual limb and thigh section is crucial to alleviate pressure on the newly amputated leg. therefore, the objective of this research was to develop a new temporary training prosthesis for individuals with new transtibial amputations. methodology a temporary training prosthesis model was designed and simulated using solidworks software (version 2020). the prototype design criteria were based on the research team's clinical experiences working with people with amputation over many years, as well as on a thorough literature review and discussions with experts. the main criteria were: • the device should allow a knee range of motion of at least 120°. • thigh section angle should be adjustable within a range of 15°. • the device should accommodate different thigh lengths by allowing for a 5 cm shift up or down in the thigh section, resulting in a total adjustment of 10 cm. • the device should alleviate pressure on the newly amputated leg. users should be able to stand and put weight on the device using only the thigh section (i.e., shank section is open). • the device is easy to don and doff. users should be able to put on and take off the prosthesis within 3 minutes. • the device should be easy to adjust for clinicians. adjustments should be possible using standard tools available in most clinical settings, with no more than 2 different tools required and taking a maximum of 15 minutes to adjust for different patients. • the device should weigh less than 4 kg, similar to a transtibial prosthesis with a thigh shell. based on these criteria, a design was developed featuring a single upright, with the thigh and shank sections unilaterally connecting to the knee joint and prosthetic foot (figure 1). the first prototype featured thigh and shank sections made of polypropylene, with the connection between the upright and the prosthetic foot made of carbon fiber, fiberglass, and aluminium. to evaluate comfort and function before testing on individuals with amputations, and to determine whether design criteria/objectives have been met, this temporary prosthesis was adapted for individuals without amputations. this approach allowed both the research team and ablebodied individuals to experience using the device and provide subjective feedback to improve the design. therefore, the shank section was made longer to match different leg lengths and to add 1 cm clearance between the distal end of the foot and the device. additionally, the contralateral leg was elevated by 10 cm using a portable shoe sole made of ethylene vinyl acetate (eva) foam, which can be used with any type of shoe. this configuration ensured that only one intact limb and the contralateral temporary training prosthesis made contact with the ground (figure 1). the research prosthetist wore the first prototype inside a prosthetic facility, using parallel bars, and provided feedback on various aspects such as comfort during use, the ability to adjust the prototype for optimal fit, ease of donning and doffing the prototype, and evaluations of stability and functionality. the thigh and shank could be adjusted using a ratchet strap or a boa system (https://www.boafit.com/en-us/bracing). the knee was free, and the length of the device was https://doi.org/10.33137/cpoj.v7i1.43034 https://www.boafit.com/en-us/bracing 3 gholizadeh h, baddour n, dudek n, lemaire e.d. a new temporary training prosthesis for people with transtibial amputation: a technical note. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.2. https://doi.org/10.33137/cpoj.v7i1.43034 canadian prosthetics & orthotics journal issn: 2561-987x temporary training prosthesis for people with transtibial amputation gholizadeh et.al, 2024 adjustable. in the initial prototype, the thigh angle could not be adjusted to accommodate hip contracture. due to the flexible nature of the thigh and shank sections, the user could not bear body weight adequately, resulting in the thigh and shank shells, shifting downward medially, where no upright support was present, by approximately 6 cm during weight-bearing. figure 1: top: initial design concept for a temporary training prosthesis for people with transtibial amputation; bottom: the contralateral leg was elevated by 10 cm to provide sufficient room for the other leg to suspend inside the device. one solution was to increase the strength of the thigh and shank sections (for example, using carbon fiber) to decrease or eliminate vertical movement during weight bearing. however, this would reduce shell flexibility, which was necessary to adjust for different thigh or shank sizes. several ideas were considered to maintain shell flexibility while controlling vertical movement during weight bearing. in one design (figure 2) a watch band concept was used to make the shells flexible in the horizontal plane while keeping them rigid in the vertical direction. however, after trying different prototypes, the team was unable to completely control vertical movement (i.e., there was still 1 cm movement). based on the issues encountered with the first prototype and prosthetist feedback, the research team modified the design by incorporating two uprights, one medial and one lateral, to better control movement in the shells, and added an adapter for adjusting the thigh section angle. throughout this iterative process, the design was refined to ensure adaptability to a broader population and meeting the specific needs of people with a transtibial amputation. the final prototype design includes two aluminium adapters (4.5 cm height, 3.6 cm length, 0.5 cm width) to connect the thigh to the support bars (uprights) on medial and lateral side. this adapter has unique threaded hole arrangements to allow for front/back shifting, up/down movement, and flexion adjustment, (figure 3). multiple iterations of this adapter were developed and tested clinically to ensure adequate adjustability to meet diverse patient needs. the thigh shell was fabricated from polypropylene (5 mm sheet), with 1 cm plastazote® foam padding inside the shell for comfort. additionally, a vinyl cover was applied to areas that contact the leg to facilitate easy cleaning (figure 3). two off-the-shelf locking knee joints (modified ring lock knee joint) from becker orthopedic were used (https://beckerorthopedic.com/product/kneejoints/1000kn eeseries/1002#selection-guide) to provide unrestricted knee motion during ambulation, with the option for the patient to lock the knee joint if necessary. to connect the joint bars to the designed adapter, several holes (one centimetre apart) were drilled into the bars to accommodate m6 screws. solidworks software simulation (using forces for a person weighing 100 kg) indicated the need for increased durability. therefore, 8 mm thick medial and lateral aluminum bars were riveted to the joint bars using 3 mm stainless steel rivets. in the shank section, sufficient room between the bars is needed to accommodate swollen and/or larger legs. therefore, the width must be adjustable to accommodate different shank sizes. the width is adjustable in the shank section using four m6 screws, and the shank section can also be shifted up or down (figure 4). ratchet strap or boa system adjustable length free knee joint soft insert the contralateral leg was elevated by 10 cm https://doi.org/10.33137/cpoj.v7i1.43034 https://beckerorthopedic.com/product/kneejoints/1000kneeseries/1002#selection-guide https://beckerorthopedic.com/product/kneejoints/1000kneeseries/1002#selection-guide 4 gholizadeh h, baddour n, dudek n, lemaire e.d. a new temporary training prosthesis for people with transtibial amputation: a technical note. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.2. https://doi.org/10.33137/cpoj.v7i1.43034 canadian prosthetics & orthotics journal issn: 2561-987x temporary training prosthesis for people with transtibial amputation gholizadeh et.al, 2024 figure 2: watch band concept for the thigh shell. after receiving approval from the university of ottawa research ethics board (h-09-22-8410), initial testing was conducted with five male individuals (82 kg (sd= 8.2), 43 years old (sd=12.5)) without amputation to ensure that the device functioned as intended and to refine the design, if necessary. figure 3: thigh shell with aluminium adapter. left: front view with vinyl cover; right: lateral view. results the device fabricated for this study was suitable for ablebodied individuals and included medium-sized thigh and shank shells designed for individuals weighing between 70 and 95 kg. the device does not require customized thigh or shank sections and can be used by able-bodied individuals after size and alignment adjustments have been made. all adjustments can be completed by a clinician or technician, using a 4 mm hex key. the designed adapter (figure 3) enables a 5 cm shift up or down to accommodate people with different thigh lengths and a 2.5 cm shift to the front or back from the knee joint center, enhancing knee stability and/or function (to provide proper and safe alignment for ambulation). additionally, this adapter allows clinicians to position the thigh at four different flexion angles (0, 5, 10, 15 degrees) to adjust for a hip flexion contracture. this adapter was made of aluminum flat bar and weighed 57 grams. the overall device weight for the non-amputee version was 3,750 grams. solidworks simulations showed that the device could tolerate loads more than 200 kg. all five testing participants successfully walked with the non-amputee version of the temporary prosthesis prototype, and the device withstood walking, sitting, and standing loads. the weight-bearing load is primarily supported by the thigh section while partially utilizing the patellar tendon and medial /lateral tibial flares. there was no weight-bearing on the foot that was suspended inside the temporary prosthesis. this device ensured that only the left leg and contralateral prosthetic foot contacted the ground. this setup provided 10 centimetres of clearance between the floor and the right foot. figure 4: the temporary training prosthesis adapted for ablebodied individuals. this version is longer in the shank section to provide sufficient room for the leg to suspend inside the device. the shank length is adjustable based on the individual’s leg length. additionally, different prosthetic feet can be used with this prototype. in this pilot study with able-bodied individuals, the pro-flex® xc foot was modified, (https://www.ossur.com/en-ca/prosthetics/feet/pro-flex-xc), creating a very short-profile prosthetic foot to avoid adding unnecessary length to the temporary prosthesis (figure 5). the modified foot was intended solely for internal use with able-bodied individuals within the research and was solely used within a prosthetic facility or a rehabilitation center (i.e., no outdoor evaluations were conducted). for testing the device on people with transtibial amputation, a shorter version of the device will be fabricated that does not require any changes to the prosthetic foot. aluminium adapter to connect the thigh to the support bars on medial and lateral side. https://doi.org/10.33137/cpoj.v7i1.43034 https://www.ossur.com/en-ca/prosthetics/feet/pro-flex-xc 5 gholizadeh h, baddour n, dudek n, lemaire e.d. a new temporary training prosthesis for people with transtibial amputation: a technical note. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.2. https://doi.org/10.33137/cpoj.v7i1.43034 canadian prosthetics & orthotics journal issn: 2561-987x temporary training prosthesis for people with transtibial amputation gholizadeh et.al, 2024 figure 5: a: pro-flex® xc foot; b: modified pro-flex® xc foot with a different adapter. discussion in this project, an adjustable temporary training prosthesis was successfully designed, and pilot tested by able-bodied individuals within a prosthetic facility or a rehabilitation centre, with no outdoor evaluations conducted. the device was easily adjusted and aligned to the participant and all participants successfully walked, stood, and sat with the prototype temporary prosthesis. to enable use by able-bodied individuals, a longer version of the device was developed. the device did not require customized thigh or shank sections. this permitted repetitive evaluations of temporary prosthesis performance. success with this testing device ensured that future evaluations for people with amputations are appropriate (i.e., device is ready for clinical evaluation). after undergoing several modifications and iterations, the final prototype device met the design criteria. the designed adapter to connect the thigh section to the uprights, allowed for 2.5 cm front/back shifting, aiding alignment adjustment. additionally, it accommodated varying thigh lengths with a 5 cm up or down movement capability and provided flexion adjustment options (0, 5, 10, 15 degrees) to address hip flexion contracture. two off-the-shelf locking knee joints (modified ring lock knee joint) used in this prototype, enabled unrestricted knee motion, crucial for smooth ambulation, and featured a safety locking mechanism for instances of instability. participants could relieve pressure on the shank section by loosening the shank straps to bear weight more or solely on the thigh section. furthermore, after instruction and practice, they donned and doffed the device within the designated 3-minute timeframe. fit and height adjustments were also straightforward, requiring only a 4 mm hex key and approximately 10-15 minutes. the device weighed less than 4 kg, even in its longer version for able-bodied individuals. device weight could potentially be further reduced in shorter versions, ensuring practicality and user comfort. to prevent pressure on the suture line in a newly amputated residual limb, weight-bearing in this device primarily occurs through the thigh section, with partial support from the patellar tendon and medial/lateral tibia flares. based on the design principles and observations during the testing phase, where individuals were able to stand using only the thigh section, it is believed that most of the patient's weight can be tolerated by the thigh section. however, there is a need for further quantitative analysis to measure the forces applied to both the thigh and shank sections for a more comprehensive understanding. in this study, participants were able to adjust pressure or weight-bearing on the thigh or shank sections by tightening or loosening the straps. evaluation with able-bodied individuals showed that this device could completely offload the foot inside the prosthesis. potentially, this non-amputee version could be used as an off-loading orthosis in case of ankle or foot fractures. compared to the pneumatic post-amputation mobility aid (ppam) and immediate post-operative rigid dressing, this device does not restrict knee movement, which is crucial in rehabilitation.8 training with the temporary prosthesis is necessary, similar to when a patient receives their first prosthesis. after fitting by a prosthetist, a physiotherapist needs to work with the patient on gait training inside the parallel bars. for safety reasons, the rehabilitation team must teach the patient how to use the device, how to adjust the weight bearing on the thigh or shank, and how to walk before they can use the temporary prosthesis outside the parallel bars. in this pilot study, the temporary training prosthesis was evaluated on five male able-bodied individuals to ensure the device’s safety and functionality. additionally, the device was solely used within a prosthetic facility or a rehab center (i.e., no outdoor evaluations). qualitative feedback was the basis for device evaluation. conclusion future research will involve testing this temporary prosthesis with five experienced prosthesis users who can provide experienced feedback on device fit and function. subsequently, a larger cohort of individuals with new transtibial amputations will be recruited to verify appropriate function in practice. this device is believed to have the potential to enhance the rehabilitation of individuals with transtibial amputation and could also serve as an off-loading orthosis for those with ankle or shank fractures. acknowledgements this project was made possible due to the generous support from the war amps. additionally, we extend our thanks to the war amps team for their invaluable support. we also express gratitude to chris kraft and adrian schellenberg at ampos orthopaedics for their assistance in providing technical advice and fabricating the prototypes. a b https://doi.org/10.33137/cpoj.v7i1.43034 https://waramps.ca/home/ 6 gholizadeh h, baddour n, dudek n, lemaire e.d. a new temporary training prosthesis for people with transtibial amputation: a technical note. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.2. https://doi.org/10.33137/cpoj.v7i1.43034 canadian prosthetics & orthotics journal issn: 2561-987x temporary training prosthesis for people with transtibial amputation gholizadeh et.al, 2024 declaration of conflicting interests the authors declare that they have no conflicts of interest to report. authors contribution hossein gholizadeh: conceptualization, design and fabrication of the prototypes, data collection and analysis, writing the manuscript, revising the manuscript, final manuscript approval, and ethics certification application. natalie baddour: conceptualization, supervision, methodology, reviewing/revising the manuscript, final manuscript approval. nancy dudek: conceptualization, reviewing/revising the manuscript, final manuscript approval. edward d. lemaire: conceptualization, supervision, methodology, reviewing/revising the manuscript, final manuscript approval. sources of support this project was made possible due to the generous support from the war amps. references 1.michael jw, bowker jh. atlas of amputations and limb deficiencies: surgical, prosthetic, and rehabilitation principles. american academy of orthopaedic surgeons rosemont, il; 2004. 2.ozyalcin h, sesli e. temporary prosthetic fitting for below-knee amputation. prosthet orthot int. 1989;13(2):86–9. doi: 10.3109/ 03093648909078218 3.baker p. below knee temporary prosthesis. aust j physiother. 1978;24(4):195–9. doi: 10.1016/s0004-9514(14)60881-3 4.schon lc, short kw, soupiou o, noll k, rheinstein j. benefits of early prosthetic management of transtibial amputees: a prospective clinical study of a prefabricated prosthesis. foot ankle int. 2002;23(6):509–14. doi: 10.1177/107110070202300607 5.pirowska a, włoch t, nowobilski r. immediate prosthesis fitting and comprehensive rehabilitation following lower limb amputation: the most important components of physiotherapy. med rehabil. 2006;10(1). 6.pelzer d, beaudart c, bornheim s, maertens de noordhout b, schwartz c, kaux jf. outcomes of patients with lower limb loss after using a training prosthesis: a retrospective case series study. healthcare 2024, 12(5), 567; doi:10.3390/ healthcare12050567 7.ortho europe [internet]. [cited 2024 mar 12]. ppam aid. available from: https://www.ortho-europe.com/product/ppam-aid/ 8.chow dh, holmes ad, lee ck, sin sw. the effect of prosthesis alignment on the symmetry of gait in subjects with unilateral transtibial amputation. prosthet orthot int. 2006;30(2):114–28. doi: 10.1080/03093640600568617 9.decker td, gradinar y, elert s, alexander jq. bent knee temporary prosthesis to support early ambulation after transtibial amputation: a case report. pm & r. 2019;11(9):1027–30. doi: 10.1002/pmrj.12136 10.champagne t. the examination of hip joint kinematics with iwalk in walking gait. undergraduate review. 2017;13(1):65–72. available at: https://vc.bridgew.edu/undergrad_rev/vol13/iss1/10 https://doi.org/10.33137/cpoj.v7i1.43034 https://waramps.ca/home/ https://www.ortho-europe.com/product/ppam-aid/ https://vc.bridgew.edu/undergrad_rev/vol13/iss1/10 volume 6, issue 2 2023 articles in this special issue has been invited and reviewed by dr. silvia ursula raschke and dr. hossein gholizadeh. d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e v o l u t i o n i n p r o s t h e t i c s & o r t h o t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x https://jps.library.utoronto.ca/index.php/cpoj/editorinchief 1 fiedler g, samosky j. user-centered design of limb prostheses: a new university course designed to spark interest in orthotics & prosthetics for bioengineering students. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.2. https://doi.org/10.33137/cpoj.v6i2.41789 stakeholder perspectives user-centered design of limb prostheses: a new university course designed to spark interest in orthotics & prosthetics for bioengineering students fiedler g1*, samosky j.2 1 department of rehabilitation science and technology, school of health and rehabilitation sciences, university of pittsburgh, pittsburgh, united states. 2 department of bioengineering, swanson school of engineering, university of pittsburgh, pittsburgh, united states. introduction much excitement has accompanied the rise of 3d printing and the associated benefits for low-cost rapid prototyping. there is no shortage of promising applications for this technology, especially in light of the continued technical advancements that make it ever more versatile and easier to use. 1 the fields of orthotics and prosthetics (o&p) are increasingly embracing the benefits of 3d printing,2 and there are many exciting developments3 which may help make established approaches more economical and – importantly – allow a fresh look at previously unsolved clinical issues, including problems such as lacking access to care, limited customizability, and restricted functionality. of these issues, access to care is a major one, especially for patients in low-income countries with insufficient medical systems,4 but also in north america, where shortages of qualified labor can be predicted based on the age profile of the practitioner population and the trajectories of disease rates for conditions such as diabetes in the general population.5, 6 there is a recognized bottleneck in growing the o&p profession, namely, the rate at which new practitioners are trained in the various educational institutions. there were, at last count, 14 accredited o&p master programs offered across the united states,7. in addition to two in canada, altogether representing the capacity of graduating perhaps 400 new professionals each year. this is perilously close to the replacement rate, considering that of some 14,000 active practitioners, assuming an average career duration of 35 years, an average of 400 are reaching retirement age each year as well. against this background, the field can barely afford to have any o&p student either fail to graduate or, upon entering the workforce, switch into a different career or become otherwise lost to the profession. open access abstract there is a current need to increase recruitment in orthotics and prosthetics, and a promising approach is to increase awareness, interest and cross-disciplinary engagement in o&p among students of allied disciplines such as bioengineering. we describe a new interdisciplinary course we jointly developed at the university of pittsburgh and deployed for the first time in the spring of 2023. the course was built on core foci of human-centered design, design thinking, experiential learning, 3d printing, creative problem-solving and prototyping. we leveraged a real-world project-based learning approach that included early and ongoing involvement of student teams with clients who used prosthetics. we explored creating a learning environment in which bioengineering students were motivated to learn about the o&p field by partnering with clients to investigate their unmet prosthetic needs and invent new solutions, with computer-aided design and 3d printing as key enabling technologies. each student team produced an individually designed and fitted device for a specific application for a person with limb difference. student feedback was positive throughout with several recipients expressing enthusiasm about the field of o&p and about the opportunity to work with actual patients. several students stated their new-found interest in pursuing a career in the field. we believe that this sort of class offering could be implemented in many institutions that host o&p graduate programs, to raise awareness of the profession and attract more and better prepared applicants. citation fiedler g, samosky j. user-centered design of limb prostheses: a new university course designed to spark interest in orthotics & prosthetics for bioengineering students. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.2. https://doi.org/10.33137/cpoj.v6i2.41 789 keywords user-centered design, design thinking, 3d printing, prototyping, education, outreach, professional development * corresponding author: goeran fiedler, phd department of rehabilitation science and technology, school of health and rehabilitation sciences, university of pittsburgh, pittsburgh, united states. e-mail: gfiedler@pitt.edu orcid id: https://orcid.org/0000-0003-1532-1248 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.2. 2023 special issue https://doi.org/10.33137/cpoj.v6i2.41789 https://doi.org/10.33137/cpoj.v6i2.41789 https://doi.org/10.33137/cpoj.v6i2.41789 https://orcid.org/0000-0003-1532-1248 https://jps.library.utoronto.ca/index.php/cpoj/index 2 fiedler g, samosky j. user-centered design of limb prostheses: a new university course designed to spark interest in orthotics & prosthetics for bioengineering students. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.2. https://doi.org/10.33137/cpoj.v6i2.41789 canadian prosthetics & orthotics journal issn: 2561-987x spark interest in orthotics & prosthetics for bioengineering students fiedler g, and samosky j, 2023 (special issue) recruiting students who are both passionate about the profession and well prepared to be successful in it is a key to mitigating those issues. ironically, the aforementioned buzz around 3d printing may be one vehicle to help with student engagement and recruitment. o&p is still a somewhat obscure field and is not at front of mind as a viable career choice for many high school or college students pondering their professional future. this is supported by anecdotal evidence: a recurring theme in the essay portions of most applications to o&p graduate programs is how the applicant has only by fortuitous happenstance become aware of the existence of the profession. this generally led to rapidly realizing its various exciting characteristics, including the ability to directly help patients, working with a broad range of materials and techniques, and the potential to have an impact and contribute to the advancement of the small field. while difficult to quantify, it is safe to assume many students do not apply for o&p graduate schools simply because they are unaware of the field and its profound impact on the lives of patients. of course, having additional applicants would allow for more selective admission processes and/or expanded class sizes, which increases both the quality and quality of graduates to meet the needs of the field. again, based on the personal experience of one author (gf), media reporting on applications of 3d printing (a much more commonly known subject) for creating prostheses has often delivered a “lightbulb moment” for introducing young people to o&p (if the journalist had gotten around to reporting that there is indeed a specialized profession and not just hobbyists providing these devices!). there may therefore be ways of actively bridging connections with related technologies such as 3d printing to increase the applicant pool. in the university context, this includes offering introductory classes aimed at graduate and undergraduate from compatible backgrounds. for instance, students in medical engineering or bioengineering programs are often quite receptive to the idea of entering o&p when they are exposed to it in a practical way, often having had very compatible motivations for starting their engineering studies, including being drawn to problemsolving and helping people, and interest in novel technologies. with a strong background in physics, biology, materials science, problem-solving, design and prototyping, bioengineering students are also quite well prepared to succeed in the o&p curriculum. the first step could be an elective class offering that helps them fulfil some of the requirements for their undergrad degree while effectively introducing them to o&p. the authors have recently developed and pilot-tested such a class with promising success and believe that this approach could be adopted in other institutions as well. methodology the three-credit course was divided in two distinct halves: 1) a theoretical part to introduce the students to the basics of prosthetic management of limb loss, including the typical patient profile, prosthetic componentry, and workflows in the clinic in the first seven weeks of the semester, and 2) a practical part that was dedicated to designing and fabricating an actual prototype device in small group work, capped by final presentations/demonstrations in the remaining seven weeks. beyond the lecture hall, class meetings were scheduled in the various fabrication laboratories within the institution, including the 3d-printing lab and the o&p teaching lab. guest speakers were invited for several sessions to round out the covered content and provide interesting perspective. a written exam was administered at the midterm point and factored in the grade composition along with short quizzes and the final project reports and presentations. we decided early in course design that, while computeraided design (cad) and 3d printing would be core enabling technologies presented in the course, we wanted the prime focus of our students’ learning experience to be people who have unmet needs in prosthetic design. putting a person at the center of the learning and design process is foundational to user-centered design or human-centered design,8,9 and stands in contrast to approaches that center a particular technology or technical method in the learning process. we adopted a design thinking approach which emphasizes empathy, deep investigation of problems before pursuing solutions, broad ideation before converging on trial solutions, early and frequent prototyping of trial solutions, and an iterative, empirical, evidence-based approach to making design decisions (rather than making choices based on untested and aspirational assumptions). we particularly emphasized the importance of problem discovery as an essential and foundational tool to achieving success in creating a solution that will ultimately be effective for a user or client in real-world circumstances. problem discovery involves first determining what is the “right” problem or problems to solve among the myriad possible problem formulations that may arise in a real-world design context. this process exercises and leverages basic human skills like talking to another person and learning to actively listen in ways that develop empathy between designer and client, and ideally actively engages the client as a codesigner in the solution-finding process, rather than as a “subject”. to implement these concepts and methods from design thinking in our course in a practical and impactful manner, we arranged for three users of prosthetics (clients of author gf) to participate in the 3rd weekly class session and then continue to work with our students during the 14-week semester. to increase the impact and student engagement of this introductory experience, we employed a “dramatic reveal” of these clients to the students during a class session. this enabled the students to practice skills in listening, interviewing and problem discovery within minutes https://doi.org/10.33137/cpoj.v6i2.41789 3 fiedler g, samosky j. user-centered design of limb prostheses: a new university course designed to spark interest in orthotics & prosthetics for bioengineering students. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.2. https://doi.org/10.33137/cpoj.v6i2.41789 canadian prosthetics & orthotics journal issn: 2561-987x spark interest in orthotics & prosthetics for bioengineering students fiedler g, and samosky j, 2023 (special issue) of the topics being introduced in the classroom. in the first hour of this class session the students received an introduction to design thinking, with illustrative examples provided for assistive technology applications. this was followed by an overview of problem discovery and an introduction to interviewing techniques. the students engaged in a preliminary exercise in which they interviewed each other. we then informed the students they would soon be able to apply the interviewing methods they just learned to better understand how to improve the prosthesis experience for several actual users of prosthetics – at which point we immediately welcomed our three clients into the classroom. after they briefly shared their backgrounds with the students, we formed multiple teams each consisting of one client and several students. these teams then spent about an hour in small-group discussion, providing the start of our students’ needs-finding process (figure 1). we provided three prompts to our student teams before they began their interviews: • before we interviewed our client/design partner, we thought: • after our interview, we now know: • one thing we were surprised to learn was: each team then shared their answers to the above prompts during a wrap-up class discussion. we were highly impressed by the insights shared by the students, often indicating ways their assumptions going into the interviews had been significantly changed by speaking with an actual user of a prosthesis. feedback from the students was also overwhelmingly positive, with many indicating this experience marked a watershed moment in their motivation toward the course content and their enthusiasm for engaging in new prosthetic designs to address specific client needs. figure 1: a student team interviews a user of prostheses at the start of a process of understanding unmet needs and discovering problems to design solutions for using a human-centered methodology. results while the limb loss levels of the invited patient models – in this case including individuals with trans-femoral, transradial, and trans-humeral amputations as well as one with congenital hand defect – somewhat predetermined the nature of the student-designed devices, it was deliberately left an open-ended question what clinical need exactly each group would identify and try to solve. eventually, the four group projects in this iteration of the course were (a) an adapter to improve grip on a cello bow for the user of a myoelectric hand (figure 2), (b) an adapter to facilitate safe operation of a manual-shift sportscar for the user of a bodypowered prosthetic arm (figure 3), (c) a prosthesiscompatible elastic sleeve with vibration motors for pain relief for a trans-femoral prosthesis user, and (d) a self-leveling prosthetic wrist joint intended to improve safe carrying of open containers. projects were evaluated using a grading matrix with the criteria design selection, prototype development, documentation, and justification (table 1). all students easily received passing grades. figure 2: cello bow holding adapter. figure 3: stick-shift to prosthetic hook adapter. feedback on the course, both from the students and the patient models, was positive throughout. all enjoyed the collaborative and creative atmosphere. the engineering students were especially appreciative of the opportunity to work with the actual user of their designs and clearly were motivated to put forth their best effort. the ability to observe the direct results of their work provided a sense of achievement and some memorable moments, for instance, when on one occasion the entire lab quieted down to listen https://doi.org/10.33137/cpoj.v6i2.41789 4 fiedler g, samosky j. user-centered design of limb prostheses: a new university course designed to spark interest in orthotics & prosthetics for bioengineering students. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.2. https://doi.org/10.33137/cpoj.v6i2.41789 canadian prosthetics & orthotics journal issn: 2561-987x spark interest in orthotics & prosthetics for bioengineering students fiedler g, and samosky j, 2023 (special issue) to our cellist patient play a beautiful tune in testing his new bow adapter. structured student feedback on the class experience, as is routinely solicited by the institution was encouraging as well, with an overall rating of 4.89 on a 0-5 scale. positive student comments included statements like: “overall, this was a great course that taught me essential hands–on skills that i have yet to learn in my engineering coursework. working with patient models was also an experience that i am very grateful to have after taking this course” and “bringing in the patient models and introducing them to us is super helpful.” where students noted room for improvement, they wished for more time to be allocated to the design and prototyping work and that a nominal budget for material purchases be provided. call to action having an o&p education program housed within a university offers great opportunity for the recruitment of talented young engineers into the next generation of practitioners. we believe it is time well spent for o&p faculty to offer respective coursework, especially when they can team up with colleagues from other departments to do so. the popularity of 3d printing among students can be leveraged by designing a class to highlight this central topic as an enabling technology while centering the overall design process in a human-centered approach that maintains a top-level emphasis on the people whose unmet needs will be explored and serve as the focus for solution discovery. students may initially come for the 3d printing but stay for the experience of working with patients how only table 1: grading rubric for project report (adapted, with permission, from knowlesteachers.org10) criteria 4 points 3 points 2 points 1 point advanced exceeds expectations competent meets expectations progressing does not fully meet expectations beginning does not meet expectations design selection: can compare a range of design concepts, and select a preliminary design that best meets the identified constraints and criteria deliberately and effectively uses initial testing, data and/or research to objectively support preliminary design selection. defends preliminary design choice against other concepts in light of criteria and constraints (trade-offs) using an appropriate objective tool (e.g., decision matrix). deliberately uses initial testing, data and/or research to subjectively support preliminary design selection. defends preliminary design choice against other concepts in light of criteria and constraints (trade-offs). uses data unsystematically for preliminary design selection. selects preliminary design based on criteria that are poorly aligned with criteria or constraints. no data collected to support preliminary design selection. evidence for preliminary design choice not logical or unfounded (choices made without rationale, or based on untested assumptions or “favorite” concepts) prototype development: demonstrates form and functionality of the design by creating a working prototype. prototype meets all constraints. prototype functionality exceeds expectations of detailed final design. prototype effectively communicates the form of the detailed final design with professional level quality. prototype meets all constraints. prototype functionality matches detailed final design. prototype effectively communicates the form of the detailed final design, and exhibits appropriate quality/craftsmanship prototype meets most but not all constraints. prototype functionality partly matches expectations of detailed final design. prototype roughly communicates the form of the detailed final design. prototype meets few constraints. prototype is insufficient to demonstrate basic functionality of detailed final design. prototype does not communicate the basic form of the detailed final design. documentation: create a documentation package that clearly explains the detailed final design and corresponding testing/ validation results. design documentation is appropriately detailed and structured for the intended purpose and audience; extraneous information has been removed. documentation includes tolerances for all necessary specifications. documentation is polished and professional. design documentation is appropriately detailed and structured for the intended purpose and audience. documentation is sufficiently organized and includes all necessary specifications for assembly and/or operation. documentation is well-organized, professional, and free of mechanical errors. design documentation is detailed but may not be optimized for the designated purpose. documentation is organized and includes most of the key parameters for assembly and/or operation and contains few mechanical errors. design documentation is not appropriate for the designated audience. documentation lacks crucial information. documentation requires significant editing and/or formatting. justification: can explain the benefits and weaknesses of the design, including opportunities, tradeoffs and ideas for further improvement communicates the design’s strengths and limitations relative to competitor benchmarks and other design options. evaluates design as well as opportunities and tradeoffs in light of criteria and constraints and defends the validity of metrics used. recommends design improvements which are supported by objective evidence or data. communicates the design’s strengths and limitations relative to other design options. evaluates design as well as opportunities and tradeoffs in light of criteria and constraints. recommends design improvements which are supported by subjective evidence. communicates the design’s strengths relative to other design options. evaluates design based on criteria and constraints. recommends design improvements; no evidence is cited to support these recommendations. does not consider other design options. does not cite the criteria and constraints in evaluation of design. no suggestions for improvement are offered. https://doi.org/10.33137/cpoj.v6i2.41789 5 fiedler g, samosky j. user-centered design of limb prostheses: a new university course designed to spark interest in orthotics & prosthetics for bioengineering students. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.2. https://doi.org/10.33137/cpoj.v6i2.41789 canadian prosthetics & orthotics journal issn: 2561-987x spark interest in orthotics & prosthetics for bioengineering students fiedler g, and samosky j, 2023 (special issue) o&p can provide it. we encourage all colleagues to propose and provide such coursework where possible. acknowledgements the authors thank the guest speakers, jonathan shulgach, andrew schoff, and matthew shaw, the patient models and students who have helped make this pilot course a success. declaration of conflicting interests none. authors contribution both authors contributed equally to the research and the writing of this manuscript. sources of support “classroom to community: designing and inventing for real-world impact,” pitt seed grant, university of pittsburgh. references 1.trenfield, s.j., madla, c.m., basit, a.w., gaisford, s. the shape of 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[cited sep 19, 2023]. available from: https://www.designkit.org/resources/1.html 9.melles m, albayrak a, goossens r. innovating health care: key characteristics of human-centered design. int j qual health care. 2021;33:37-44. doi:10.1093/intqhc/mzaa127 10.engaging math and science students in engineering design [internet]. knowles academy, 2017. [cited sep 19, 2023]. available from: https://knowlesteachers.org/wpcontent/uploads/2017/10/knowlesengineering_designprocessru bric.pdf authors scientific biography goeran fiedler, phd, is an associate professor for the master of science in prosthetics and orthotics program at the university of pittsburgh. he holds graduate degrees in clinical engineering/biomechanics from the university of applied sciences giessen (germany) and in health sciences from the university of wisconsin-milwaukee. he completed his post-doctoral training in the department of rehabilitation medicine at the university of washington in seattle. he is also a credentialed prosthetist & orthotist with degrees from the german chambers of craft in thuringia and in lower bavaria, as well as 12 years of clinical work experience. his research and teaching have the overall goal to find ways of raising the quality and quantity of prosthetic & orthotic device utilization, in order to realize outcome gains that are inexpensive to achieve and applicable to a large patient population. joseph samosky, phd, is associate professor of bioengineering in the swanson school of engineering at the university of pittsburgh. he received his phd in medical engineering from mit in the harvard-mit program in health sciences and technology. over the past decade he has designed, developed and deployed new courses to foster usercentered design, innovation, creativity and project-based learning. dr. samosky has mentored over 1000 students in more than 200 design and innovation projects and his students have received numerous awards in design and innovation competitions. he has 8 issued patents to date. he also developed and directs the swanson school of engineering’s g34 design and innovation space, a student-centered home base for creative community, ideation, prototyping and invention. he received the school of engineering’s outstanding educator award in 2018 and was named higher educator of the year in 2023 by the engineers society of western pennsylvania. https://doi.org/10.33137/cpoj.v6i2.41789 https://ncope.org/index.php/home-page-v2/academic-programs/accredited-practitioner-programs/ https://ncope.org/index.php/home-page-v2/academic-programs/accredited-practitioner-programs/ https://www.designkit.org/resources/1.html https://knowlesteachers.org/wp-content/uploads/2017/10/knowlesengineering_designprocessrubric.pdf https://knowlesteachers.org/wp-content/uploads/2017/10/knowlesengineering_designprocessrubric.pdf https://knowlesteachers.org/wp-content/uploads/2017/10/knowlesengineering_designprocessrubric.pdf all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 1 2024 research article pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i1.43890 1 pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 research article detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss pousett b.m1,2 *, harasym c.c3, rapaport m.s1, richardson t1, spellen j1, moe d.w1, miller w.c4 1.barber prosthetics clinic, vancouver, canada. 2.rehabilitation sciences, faculty of medicine, university of british columbia, vancouver, canada. 3.biomechanical engineering, university of british columbia, vancouver, canada. 4.g.f. strong rehabilitation research program & department of occupational science and therapy, faculty of medicine, university of british columbia, vancouver, canada. introduction prosthetic treatment seeks to achieve a shared goal and influence a change in function. mobility is a primary goal of treatment and is supported by a comfortable prosthesis that is free of pain.1 the provision of a prosthesis occurs at two phases: initial rehabilitation and subsequent replacement socket. the baseline and end point of each phase are important milestones, and progress should be measured at these points to determine if a change has occurred and a goal has been achieved. socket comfort, pain and mobility are critical indicators of successful prosthetic treatment. however, there is little data regarding how these values change at different clinical milestones. outcome measures (oms) are a way to provide evidence of change toward a goal.2-4 the 2 minute walk test (2mwt),5 prosthetic limb users survey of mobility (plus-m),6 socket comfort score (scs),7 and pain scale (ps)8 are four oms that measure critical prosthetic treatment indicators. the canadian amputations rehabilitation evidenced-based open access abstract background: functional mobility, comfort and the absence of pain are key goals of prosthetic treatment. outcome measures (oms) evaluate the impact of treatment and normative and minimal detectable change (mdc) values are key to interpreting these scores and measuring treatment outcomes. objectives: this study seeks to 1) present practice-based normative values of four commonly used oms at four prosthetic milestones and 2) explore the mdc of the measures over the treatment period. methodology: a chart review was conducted of oms collected with individuals with lower limb loss between january 1, 2015, and december 31, 2023. this included data for individuals with unilateral transtibial (tt), transfemoral (tf) and rotationplasty (rp) amputations and bilateral transtibial amputation (btt). oms included the socket comfort score (scs), pain scale (ps), 2 minute walk test (2mwt), and prosthetic limb users survey of mobility (plus-m). data were collected at four milestone time points: (1) baseline and (2) discharge from rehabilitation for those in initial prosthetic rehabilitation, and (3) initial evaluation and (4) definitive delivery for those receiving a replacement socket. normative values and mdc values were calculated. findings: data from 30 individuals undergoing in-patient rehabilitation and 74 individuals receiving a replacement socket were included. practice-based normative data were different for each level of amputation and milestone and had the following ranges: scs: 5.7 – 9.1, ps: 0.8 – 3.7, 2mwt: 68.4 – 146.3 m and plus-m: 38.9 – 57.3. mdc values also varied based on time in treatment (rehabilitation: scs = 2.5, ps = 1.6, 2mwt = 32.6, plus-m = 8.8; replacement socket: scs = 3.1, ps = 2.6, 2mwt = 38.9, plus-m = 4.0). all measures had a statistically significant change over the intervention, however, no average scores changed by greater than the mdc. conclusions: the normative data and mdc scores demonstrate the ps & plus-m are useful measures of pain and mobility at all points within treatment. the 2mwt is indicated for individuals in rehabilitation, while the scs is indicated for those receiving a replacement socket, as both effectively measure treatment goals that are particularly important for each phase of rehabilitation. this provides clinicians with practice-based evidence that enables them to interpret om scores, a critical part of the decision-making process along the treatment journey. article info received: august 22, 2024 accepted: october 12, 2024 published: october 25, 2024 citation pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj .v7i1.43890 keywords prosthesis, amputation, lower limb prosthesis, outcome measure, socket comfort, mobility, pain, practice-based evidence, 2mwt, functional mobility, rehabilitation, plus-m * corresponding author: brittany mae pousett, cp(c), msc. 540 se marine dr, vancouver, bc, canada, v5x 2t4 tel: 604.321.1115. e-mail: brittany@pousett.ca orcid id: https://orcid.org/0000-0002-2272-7847 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 1, article no.7. 2024 https://doi.org/10.33137/cpoj.v7i1.43890 https://doi.org/10.33137/cpoj.v7i1.43890 https://doi.org/10.33137/cpoj.v7i1.43890 mailto:brittany@pousett.ca https://orcid.org/0000-0002-2272-7847 https://jps.library.utoronto.ca/index.php/cpoj/index 2 pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 canadian prosthetics & orthotics journal issn: 2561-987x detecting changes in comfort, pain and mobility pousett et al., 2024 review group9,10 and the american academy of orthotists and prosthetists11 recommend these measures and their constructs as they capture important and relevant information and are easy to integrate into the clinic environment. however, to be useful, om scores need to have meaning. one form of meaning is normative values. normative values, the average values for a population, are dependent on population demographics (e.g., age, sex, etc.) and pathologies (e.g., cause of amputation) and allow the clinician to compare the patient’s outcome with others in the population.12 normative values are often collected in research settings, where population characteristics and administration methods may differ from clinical environments.13 practice-based normative values provide evidence based in clinical practice. practice-based normative values are similar to the clinical population and are also recorded in the clinical setting. the minimal detectable change (mdc) of a measure is the smallest change that falls outside of measurement error.12 this is crucial for measuring treatment outcomes as if a patient’s om score has changed by greater than the mdc, it indicates that they have experienced a true change.14 while some oms have interpretability values from research and clinical settings (e.g., the 2mwt),15-17 many studies do not specify the timepoint within the treatment pathway and cannot show how an om changes as the individual progresses. the relationship between om scores differs at different milestones,18 and we expect that the practicebased normative values and changes in measures will be different at different milestones as well. for example, decreased functional mobility is a common consequence of lower limb loss19 that rehab programs seek to address. we hypothesized those going through initial prosthetic rehabilitation may have a larger change in the oms measuring functional mobility, as demonstrated by increased distance walked in the 2mwt. without clinical values to give meaning to om scores and their changes, the intended purposes for using oms cannot be realized.4,13 our research objectives were to: a. present practice-based evidence of the normative values of four commonly used oms at four milestones: (1) baseline and (2) discharge from rehabilitation for individuals in initial prosthetic rehabilitation, and (3) initial evaluation and (4) definitive delivery for those receiving a replacement socket; b. explore which oms scores changed by more than the mdc over the treatment period and may be useful for measuring the effectiveness of prosthetic treatment interventions. methodology study design & sample a chart review of patients who had oms data recorded at barber prosthetics clinic between january 1, 2015, and december 31, 2023, was conducted. the study was approved by the clinical research ethics board at the university of british columbia (h21-02131; h24-00501). to be included, patients had to be over the age of 18, have unilateral or bilateral amputations above the ankle and below the hip, and have oms data recorded in their chart. patients were excluded if they did not have oms data for at least one om at baseline and discharge from rehabilitation, or initial evaluation and definitive fitting. data were captured at two clinical milestones for each of the two distinct phases of the treatment journey (figure 1). initial prosthetic rehabilitation is a distinct period from the rest of the prosthetic journey due to its large learning component and rapid changes in socket fit and mobility. figure 1: definitions of the prosthetic milestones included in the two distinct phases of the treatment journey. outcome measures: the oms were administered by certified prosthetists who had completed computer-based training to use these four specific oms20 as well as in-person feedback to ensure consistency in administration. the scs, ps, plus-m and 2mwt were administered at clinical milestones, regardless of treatment goals. the 2mwt is a performance-based measure of aerobic capacity and functional mobility. it records how many meters an individual can walk in 2 minutes. a 10 m hallway with in-floor markings was used in most instances but walkways of different lengths were used when 10 m hallways were unavailable. the variability in hallways length is a known issue in the clinic use of the 2mwt.13 assistive devices were used if needed. the 2mwt has published normative values based on age, sex, cause of amputation, https://doi.org/10.33137/cpoj.v7i1.43890 https://www.barberprosthetics.com/ 3 pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 canadian prosthetics & orthotics journal issn: 2561-987x detecting changes in comfort, pain and mobility pousett et al., 2024 and level of amputation which makes it easy to interpret to the context of the patient.5,15,21-24 it is the only measure that has values specified at clinical milestones, as one study presented scores at discharge from rehabilitation and a later follow-up.16 the measure has test-retest reliability for individuals with limb loss, icc = 0.83, and an mdc of 34.4 m.24 the plus-m is a 12 item self-report mobility survey that asks individuals with limb loss to rate their ability to complete tasks on a 5-point scale ranging from without any difficulty [5] to unable to do [1].25 clinicians read aloud the survey for patient who struggled to complete the test independently. the plus-m is scored by converting the raw scores to a t-score, where a t-score of 50 relates to the average score of the original development sample.25 testretest reliability has icc=0.96, and the mdc-90 of the tscore of 4.50.26 the scs and ps are self-report measures of socket comfort and pain intensity, respectively. they are both rated verbally on a numerical 11-point scale from 0 (scs: least comfortable socket they can imagine, or ps: no pain) to 10 (scs: most comfortable socket they can imagine, and ps: worst pain imaginable). the test-retest reliability of the scs is icc=0.77 and the mdc is 2.82.26 the ps, while previously used with people with amputations27 has little specific interpretability data published to date. a study with a combined sample of individuals with amputations and spinal cord injuries found a change of 1.8 corresponded to a meaningful change in pain.27 this measure is similar to the patient-reported outcomes measurement information system 29-item profile (promis-29) pain intensity, which asks the identical question but has instructions that suggest a different time period (7 days vs 24 hours).8,28 the promis-29 pain intensity has test-retest reliability of icc = 0.87 and an mdc of 1.97. we used the ps due to its clinical prominence, and as the promis-29 represents the best available evidence, we relied on it to inform our interpretation of the ps.26 data collection: oms data, treatment milestones, and demographic data including level of amputation, cause of amputation, time since amputation, sex, and date of birth were extracted from medical records. if a patient reached a milestone multiple times within the included dates (i.e., they had more than one replacement socket), the most recent milestone was used. patient charts were included if they had data for at least one of the oms at either baseline and discharge from rehabilitation, or initial evaluation and definitive fitting, so that change scores could be calculated. analysis: analysis was done using r studio (posit software, pbc). demographic data were analyzed using descriptive statistics and partitioned by level of amputation and phase of the treatment journey. practice-based normative values for each measure were partitioned by treatment milestone. mean changes in the om scores over the paired milestones were presented. the mean change values were compared to calculated mdc values which were calculated using the following formula, using previously established icc values. mdc=1.645* √2* sem sem=standarddeviationbaselinescores√(1-icctest-retest) all mdc values use a 90% confidence interval to be consist with what is reported in the literature.24 the significance of the mean change over treatment was calculated using a 95% confidence interval (a = 0.05). a beneficial change for the patient would include a positive increase in scs, plus-m and 2mwt by greater than the mdc, along with a negative change in the ps by more than the mdc. results data were collected from 30 individuals going through initial prosthetic rehabilitation and 74 individuals getting a replacement socket (table 1). most individuals in rehabilitation were males with transtibial amputations, with a mean age of 65.7 years (sd = 12.9). among those receiving a replacement socket, the majority were also male, with a mean age of 48.5 years (sd = 16.8), and had amputations due to various causes. the subgroup with rotationplasty amputations was mostly female, with a mean age of 29.3 years (sd = 5.4). practice-based normative values practice-based normative values are presented in table 2. the numbers of individuals included for each measure range and some measures are marked as n/a because it is not always clinically appropriate to administer every measure. for individuals in rehabilitation, males were found to have higher scs and lower ps at baseline and higher plus-ms scores at both baseline and discharge from rehabilitation. however, for individuals receiving a replacement socket, there is no difference in scores across sexes at either milestone. changes in scores over treatment interventions average changes in scores and the percentage of scores that changed by more than the mdc are presented in table 3. for individuals in rehabilitation, the ps & 2mwt measured change most often, and the scs measuring change the least often. for individuals receiving a replacement socket, the plus-m measured changes most often while the 2mwt rarely did. https://doi.org/10.33137/cpoj.v7i1.43890 4 pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 canadian prosthetics & orthotics journal issn: 2561-987x detecting changes in comfort, pain and mobility pousett et al., 2024 discussion through analyzing data from individuals in prosthetic rehabilitation or receiving a replacement socket, we were able to provide practice-based normative values for four commonly used oms (scs, ps, 2mwt & plus-m) based on level of amputation at four distinct clinical milestones. we were also able to provide practice-based mdc scores as well as demonstrate which measures recorded a change at which treatment milestones. this information provides clinicians valuable information about interpreting om scores at these clinical milestones. as each outcome measure had a different purpose, it is often advantageous to use a variety of oms to measure the changes in distinct aspects of the individuals experience (e.g. comfort and functional mobility). the practice-based normative values, mean changes in scores, and calculated mdc values are different for each measure at the different milestones, highlighting the importance of interpreting the data within these strata and the novelty of this approach. when comparing calculated mdc values to those published, the calculated values are often smaller for those in rehabilitation and greater for those receiving a replacement socket. this value is related to the homogeneity of the scores for our specific populations, with our population having less variability in om scores at baseline for those in rehabilitation and more variability in om scores at initial evaluation for those receiving a replacement socket. table 1: demographic information of individuals included. individuals with transtibial amputations receiving initial prosthetic rehabilitation (n = 27) receiving a replacement socket (n = 53) age (years) – mean (sd) 65.8 (13.6) 49.9 (16.0) male – number (%) 18 (66.7%) 43 (81.1%) etiology – number (%) cancer/tumor congenital injury/trauma vascular/diabetes unknown/other 1 (3.7%) 1 (3.7%) 2 (7.4%) 22 (81.5%) 1 (3.7%) 5 (9.4%) 2 (3.8%) 23 (43.4%) 21 (39.6%) 2 (3.8%) time since amputation (years) – mean (sd) 0.5 (1.0) 9.1 (12.0) time in rehab (weeks) – mean (sd) 6.4 (4.5) n/a individuals with transfemoral amputations receiving initial prosthetic rehabilitation (n = 3) receiving a replacement socket (n = 10) age (years) – mean (sd) 65.0 (3.6) 51.0 (22.3) male – number (%) 2 (66.7%) 8 (80.0%) etiology – number (%) cancer/tumor congenital injury/trauma vascular/diabetes 3 (100.0%) 3 (30.0%) 1 (10.0%) 4 (40.0%) 2 (20.0%) time since amputation (years) – mean (sd) 0.4 (1.0) 22.2 (14.2) time in rehab (weeks) – mean (sd) 7.4 (4.2) n/a individuals with rotationplasty amputations receiving initial prosthetic rehabilitation (n = 0) receiving a replacement socket (n = 4) age (years) – mean (sd) 29.2 (5.3) male – number (%) 1 (25.0%) etiology – number (%) cancer/tumor congenital unknown 1 (25.0%) 2 (50.0%) 1 (25.0%) time since amputation (years) – mean (sd) 20.0 (10.9) individuals with bilateral transtibial amputations receiving initial prosthetic rehabilitation (n = 0) receiving a replacement socket (n = 7) age (years) – mean (sd) 45.6 (12.8) male – number (%) 5 (71.4%) etiology – number (%) injury/trauma vascular/diabetes unknown 2 (28.6%) 2 (28.6%) 3 (42.9%) time since amputation (years) – mean (sd) 4.0 (3.3) note: time since amputation for those receiving initial prosthetic rehabilitation was the time between the discharge from rehab appointment and their amputation date. time since amputation for those receiving a replacement socket was the time between the definitive delivery appointment and their amputation date. https://doi.org/10.33137/cpoj.v7i1.43890 5 pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 canadian prosthetics & orthotics journal issn: 2561-987x detecting changes in comfort, pain and mobility pousett et al., 2024 the demographics were different for the two segments of the treatment journey, further highlighting the difference in new patients seen in rehabilitation hospitals and experienced patients seen in clinics. those in rehabilitation are older and have amputations largely due to vascular reasons while those receiving a replacement socket are younger and have a wider variety of etiologies of amputation. scs for individuals in rehabilitation, scs were high at baseline and remained high at discharge from rehabilitation. because the scores remained constant, the average change in scs did not change by the mdc and individuals experienced change greater than mdc only 19% of the time. this is likely because in this specific clinical environment, patients typically see their prosthetist at least table 2: clinical normative data for outcome measures used in prosthetic treatment. scs 2mwt (m) ps plus-m individuals receiving initial prosthetic rehabilitation baseline transtibial (n = 24, 20, 17, 26) – mean (sd) 7.2 (2.3) 68.4 (32.4) 2.7 (1.9) 38.9 (19.4) transfemoral (n = 2, 0, 0, 2) – mean (sd) 7.5 (0.7) n/a n/a 45.6 (4.0) discharge from rehabilitation transtibial (n = 24, 20, 17, 26) – mean (sd) 8.5 (1.0) 107.4 (32.3) 1.0 (1.0) 53.4 (8.4) transfemoral (n = 2, 0 ,0, 2) – mean (sd) 8.5 (0.7) n/a n/a 43.7 (4.8) individuals receiving a replacement socket initial evaluation transtibial (n = 56, 50, 48, 56) – mean (sd) 5.7 (2.9) 126.5 (36.4) 3.7 (3.2) 51.6 (9.1) transfemoral (n = 10, 12, 10, 12) – mean (sd) 5.8 (2.8) 104.7 (53.8) 3.6 (3.1) 48.2 (6.4) transtibial, bilateral (n = 8, 6, 5, 8) – mean (sd) 7.3 (1.6) 132.3 (48.2) 2.5 (1.3) 53.0 (6.6) rotationplasty (n = 3, 3, 2, 4) – mean (sd) 8.0 (0.0) 100.7 (38.2) 1.5 (0.7) 57.2 (11.0) definitive fitting transtibial, (n = 56, 50, 48, 56) – mean (sd) 8.9 (1.2) 132.6 (41.4) 1.4 (1.7) 53.2 (11.4) transfemoral (n = 10, 12, 10, 12) – mean (sd) 8.0 (2.9) 107.6 (42.2) 3.1 (3.5) 51.2 (9.3) transtibial, bilateral (n = 8, 6, 5, 8) – mean (sd) 9.1 (0.8) 146.3 (56.4) 0.8 (1.0) 52.9 (8.0) rotationplasty (n = 3, 3, 2, 4) – mean (sd) 9.0 (1.0) 112.7 (46.5) 1.5 (0.7) 57.3 (9.7) note: the n values are listed as (nscs, n2mwt, nps, nplus-m) and provide the number of participants included in the scs, 2mwt, ps and plus-m calculations respectively. table 3: average changes in scores for individuals with lower limb loss over prosthetic treatment. n change in score – mean (sd) (m) significance – p-value (0.05) mdc 90 calculated % changed by mdc calculated individuals receiving initial prosthetic rehabilitation scs (n = 26) 1.3 (2.4) 0.013* 2.5 19% 2mwt (n = 21) 37.9 (30.0) <0.000* 32.6 48% ps (n = 18) -1.2 (2.4) 0.053 1.6 50% plus-m (n = 28) 13.3 (18.3) <0.000* 8.8 43% individuals receiving a replacement socket scs (n = 68) 2.9 (2.9) <0.000* 3.1 39% 2mwt (n = 62) 6.3 (18.6) 0.009* 38.9 6% ps (n = 59) -1.9 (2.9) <0.000* 2.6 31% plus-m (n = 70) 2.3 (5.6) <0.00* 4.0 47% * indicates change in score is significant from before to after treatment using a = 0.05. https://doi.org/10.33137/cpoj.v7i1.43890 6 pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 canadian prosthetics & orthotics journal issn: 2561-987x detecting changes in comfort, pain and mobility pousett et al., 2024 once a week for any adjustments to ensure the socket is comfortable. between initial evaluation and definitive fitting, average change in scs scores were just below the mdc and a change greater than the mdc was experienced by 40% of individuals. limb volume changes are a common clinical reason for replacement sockets, leading to uncomfortable limb-socket interfaces and lower scs at initial evaluation. scs were high when individuals received their definitive prostheses, suggesting the goal of providing a comfortable interface had been achieved. while transtibial and transfemoral prosthesis users reported similar levels of comfort at initial evaluation, transfemoral prosthesis users reported lower levels of comfort at the definitive fitting. this supports previous research which found that individuals with transfemoral amputations experience diminished comfort and functional outcomes than those with other levels of amputations.29 the nature of the intimacy of the socket fit could be a reason transfemoral users have less comfortable fitting sockets. in addition, individuals using rotationplasty prostheses had high levels of comfort at both time points. this is hypothesized to be because the deterioration of external prosthetic joints and the need for a new socket with new joints is a common clinical reason for receiving a replacement socket and does not reflect in comfort scores. previous studies found average scs to be 4.8 before receiving a new socket, 6.8 twenty minutes after receiving a new diagnostic socket, and 8.4 for individuals who had been using a well-fitting socket for 6 months to 5 years, based on a sample of various lower extremity amputation.7 the current sample had higher socket comfort scores at all time points, which may be due to having fewer transfemoral users, a younger average age, and a wider variety of amputation etiologies. the scs is suited for use with patients receiving a replacement socket, as it is easy to use, aligns with a common treatment goal, and frequently captures the impact the intervention has at this milestone. it also can be useful for guiding treatment decisions and adding clarity to the communication between patients and their prosthetists.18 for those in rehabilitation, while using the scs in this setting can facilitate clinical conversation, it may not be as appropriate for measuring the impact of this intervention. ps for individuals in rehabilitation, ps scores were low at baseline and remained low at discharge from rehabilitation, indicating an absence of pain. ps values negatively correlate with scs values as the presence of comfort often correlates to the absence of pain.18 while the ps does not have previous normative values published, the values at definitive fitting were lower than the pain intensity scale from the promis-29 which reported an average score of 3.3 for a population that was older, with higher levels of amputations and more vascular etiologies30 than the current sample. for individuals receiving a replacement socket, pain levels decreased from initial evaluation to definitive fitting, inversely to scs, again demonstrating the clinical goal has been met in these instances. the ps is suitable for use with patients in rehabilitation and with patients receiving a replacement socket as it captured change over 50% and 31% of the time, respectively. the ps is easy to use, aligns with a common treatment goal and provides clinicians with helpful information. 2mwt 2mwt scores changed notably for the transtibial population as individuals progressed through their rehab and were able to walk further. 2mwt scores (68.3 m at baseline in rehabilitation and 107.4 m at discharge from rehabilitation) were notably higher than previously reported patients in rehabilitation (20.4 m for males and 22.5 m for females at baseline and 46.0 m for males and 29.1 m for females at discharge).16 the current sample had similar mean ages and male/female composition, with no difference in mean scores based on sex. however, brooks et al. measured the baseline scores earlier in the fitting process and had a shorter average time from fitting to discharge which may have contributed to the lower scores. in addition, individuals with bilateral transtibial limb loss had the highest 2mwt scores at initial evaluation and definitive delivery. previous research has found that individuals with unilateral transtibial amputations tend to have higher 2mwt scores than those with bilateral transtibial amputations during rehabilitation16 and it was hypothesized this relationship would exist for replacement sockets as well. perhaps the younger mean age of the individuals with bilateral amputations in our study led to their higher functional mobility. for individuals in rehabilitation, the average change in score was larger than the mdc and the 2mwt measured change greater than mdc 48% of the time. this demonstrated that while this measure is an effective way to document changes in functional mobility during initial rehabilitation, preamputation activity and comorbidities, and not just the disease or rehabilitation intervention, impact aerobic capacity and functional mobility.31 for individuals receiving a replacement socket, our sample also had slightly higher 2mwt scores than most previous studies (mean scores 98.8 – 113.2),15,21-23 but less than the most recent study (mean score 154.3 m).32 scores tend to be higher in samples with more traumatic and fewer vascular amputations, more distal amputation levels, and younger populations. although it was hypothesized that a https://doi.org/10.33137/cpoj.v7i1.43890 7 pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 canadian prosthetics & orthotics journal issn: 2561-987x detecting changes in comfort, pain and mobility pousett et al., 2024 new, well-fitting socket would improve walking capacity, this was not the case as it only measured a change greater than mdc 6% of the time. this demonstrates that straight line walking capacity is not affected by this intervention. perhaps a measure including functional tasks could be more suited to capture a change in this population. there are also personal and environmental considerations such as co-morbidities, cardiac function, and confidence that determine walking capacity. the 2mwt is most useful for individuals in rehabilitation as it is easy to administer and measures the impact of prosthetic rehabilitation on a patient’s functional mobility, which is a primary goal of rehabilitation.1 for individuals receiving a replacement socket, the 2mwt is not recommended as it does not capture the change that this treatment has. plusm for most individuals in rehabilitation, plus-m scores were below those of the original plus-m development sample, which is intuitive as they were early in their rehabilitation.25 plus-m scores at definitive fitting were close to the plusm development sample for individuals with transtibial and transfemoral amputations due to trauma, which was the most common cause of amputation reported in this subgroup of our sample.25 for individuals in rehabilitation, the average change in score was larger than the mdc and measured a change greater than mdc 43% of the time. for individuals receiving a replacement socket, the average change in plus-m score was below the mdc, but it did capture a change greater than mdc 47% of the time, demonstrating it is more effective at capturing changes in mobility for this population than the 2mwt was. the plus-m is useful for providing a snapshot of an individual’s perceived mobility at a point in time and successfully captures the change that prosthetic treatment has on an individual at both parts of the treatment journey. perhaps for those whose mobility is the primary goal or concern, such as during the aging process, the usefulness of this measure would be even greater. limitations the data were collected in a single clinical practice. for the individuals in the rehabilitation sample, the age, sex, and etiology of amputation reflect the incidence of amputation in canada. however, less individuals with transfemoral amputations were represented in the current study than the incidence rates suggests.33 for those receiving a replacement socket, the current sample was younger, had less individuals with transfemoral amputations, and had more individuals represented with traumatic, cancer or congenital amputations.33 but, this helps to ensure that demographics reflect other groups at similar milestones. it should be noted that individuals in rehabilitation with transfemoral limb loss and individuals with rotationplasty amputations receiving a new socket had small sample sizes and therefore are not representative of that population and should be interpreted as such. however, it is the first study to our knowledge that provides evidence for using oms with this rotationplasty population and has been kept in to provide initial evidence for this group. in addition, this is one of the first studies presenting information on the pain scale for use with people with amputations. the practice-based normative values can begin to form the evidence on this measure. however, the mdc values were calculated using information from the promis-29 and should be cautiously interpreted. future work can address the psychometric properties of the ps. finally, since oms were not selected based on treatment goals, they may be measuring constructs that were not addressed in treatment. future work should integrate both treatment milestones and treatment goals to provide the most accurate assessment of the ability of oms to capture changes due to treatment. conclusion this study provides clinicians with detailed information on how to interpret scores in clinical environments. the impact of the treatment was measured before and after each intervention using different oms, thus indicating the need to consider treatment milestones when choosing oms for clinical use. placing more responsibility on the clinician to select an om based on the patient’s goal and milestones could provide more meaningful results the development and use of outcome measures that capture changes at specific treatment milestones and are easy for both patients and prosthetists to use are critical for the successful implementation of these measures. acknowledgements we would like to thank the team at barber prosthetics clinic for their support in this project, as well as all the patients whose data was included in the analysis. declaration of conflicting interests the authors have no conflicts of interest to disclose. authors contribution • brittany mae pousett: conceptualization, study design, data curation, formal analysis, project administration, & writing – original draft, review & editing. • charlene c harasym: study design, data curation, formal analysis, & writing – review & editing. • malena sofia rapaport: conceptualization, study design, investigation & writing – review & editing. https://doi.org/10.33137/cpoj.v7i1.43890 https://www.barberprosthetics.com/ 8 pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 canadian prosthetics & orthotics journal issn: 2561-987x detecting changes in comfort, pain and mobility pousett et al., 2024 • tessa richardson: investigation & writing – review & editing. • jesse spellen: investigation & writing – review & editing. • david w moe: conceptualization, investigation & writing – review & editing. • william c miller: conceptualization, study design, investigation, supervision & writing – review & editing. sources of support research reported in this article was not supported by any funding agency in the public, commercial, or not-for-profit sectors. references 1.webster jb, hakimi kn, williams rm, turner ap, norvell dc, czerniecki jm. prosthetic fitting, use, and satisfaction following lower-limb amputation: a prospective study. j rehabil res dev. 2012;49(10):1493–504. doi: 10.1682/jrrd.2012.01.0001 2.jette du, halbert j, iverson c, miceli e, shah p. use of standardized outcome measures in physical therapist practice: perceptions and applications. phys ther. 2009;89(2):125–35. doi: 10.2522/ptj.20080234 3.young j, rowley l, lalor s. use of outcome measures among prosthetists and orthotists in the united kingdom. j prosthet orthot. 2018;1–6. doi: 10.1097/jpo.0000000000000198 4.england dl, miller ta, stevens pm, campbell jh, wurdeman sr. mobility analysis of amputees (maat 7): normative mobility values for lower limb prosthesis users of varying age, etiology, and amputation level. am j phys med rehabil. 2022:850-8. doi: 10.1097/phm.0000000000001925 5.gaunaurd i, kristal a, horn a, krueger c, muro o, rosenberg a, et al. the utility of the 2-minute walk test as a measure of mobility in people with lower limb amputation. arch phys med rehabil. 2020;101(7):1183–9. doi: 10.1016/j.apmr.2020.03.007 6.hafner bj, gaunaurd ia, morgan sj, amtmann d, salem r, gailey rs. construct validity of the prosthetic limb users survey of mobility (plus-m) in adults with lower limb amputation. arch phys med rehabil. 2017;98(2):277–85. doi: 10.1016/j.apmr.2016.07. 026 7.hanspal rs, fisher k, nieveen r. prosthetic socket fit comfort score. disabil rehabil. 2003;25(22):1278–80. doi:10.1080/ 09638280310001603983 8.numeric pain rating scale instructions [internet]. shirley ryan ability lab. rehab measures database. 2017; [cited 2024, sep 29]. available from: https://www.sralab.org/rehabilitationmeasures/numeric-pain-rating-scale 9.deathe ab, wolfe dl, devlin m, hebert js, miller wc, pallaveshi l. selection of outcome measures in lower extremity amputation rehabilitation: icf activities. disabil rehabil. 2009;31(18):1455–73. doi: 10.1080/09638280802639491 10.hebert js, wolfe dl, miller wc, deathe ab, devlin m, pallaveshi l. outcome measures in amputation rehabilitation: icf body functions. disabil rehabil. 2009;31(19):1541-54. doi: 10.1080/09638280802639467 11.klenow t, pousett b, wening j, cabana a, anderson c, kaluf b. outcome measures toolkit summary: lower limb prosthetics. outcomes research committee american academy of orthotists and prosthetists (aaop) [internet]. 2020; [cited 2024, sep 29]. available from: https://www.oandp.org/page/lower-limbprosthetics-outcome-measures-toolkit-summary 12.riddle dl, stratford pw. is this change real? interpreting patient outcomes in physical therapy. philadelphia: f.a. davis company; 2013. https://fadavis.com/product/physical-therapy-isthis-change-real-riddle-stratford 13.shank c, kristal a, van veld r, applegate b, gaunaurd i, gailey r. variations in 2-minute walk test outcomes for people with lower limb amputation in the outpatient clinic and research settings. prosthet orthot int. 2022;46(2):140–7. doi: 10.1097/pxr. 0000000000000090 14.stipancic kl, yunusova y, berry jd, green jr. minimally detectable change and minimal clinically important difference of a decline in sentence intelligibility and speaking rate for individuals with amyotrophic lateral sclerosis. j speech lang hear res. 2018;61(11):2757–71. doi:10.1044/2018_jslhr-s-17-0366 15.parker k, kirby rl, adderson j, thompson k. ambulation of people with lower-limb amputations: relationship between capacity and performance measures. arch phys med rehabil. 2010;91(4):543–9. doi:10.1016/j.apmr.2009.12.009 16.brooks d, parsons j, hunter jp, devlin m, walker j. the 2minute walk test as a measure of functional improvement in persons with lower limb amputation. arch phys med rehabil. 2001;82(10):1478–83. doi: 10.1053/apmr.2001.25153 17.newton kl, evans c, osmotherly pg. the timed up and go and two-minute walk test: exploration of a method for establishing normative values for established lower limb prosthetic users. eur j physiother. 2016;18(3):161–6. doi: 10.3109/21679169.2016. 1150511 18.pousett bm, harasym cc, rapaport ms, moe dw, miller wc. the relationship between socket comfort, pain and mobility over treatment milestones for individuals with lower limb loss. j prosthet orthot. 2024. doi: 10.1097/jpo.0000000000000516 19.mackay c, cimino sr, guilcher sjt, mayo al, devlin m, dilkas s, et al. a qualitative study exploring individuals’ experiences living with dysvascular lower limb amputation. disabil rehabil. 2022;44(10):1812–20. doi: 10.1080/09638288.2020.1803999 20.rapaport ms, negri c, pousett bm, mathis s. attitudes and behaviors toward using outcome measures in clinical practice: findings of a blended education program. prosthet orthot int. 2022;46(5):477–83. doi: 10.1097/pxr.0000000000000167 21.gremeaux v, damak s, troisgros o, feki a, laroche d, perennou d, et al. selecting a test for the clinical assessment of balance and walking capacity at the definitive fitting state after unilateral amputation: a comparative study. prosthet orthot int. 2012;36(4):415–22. doi: 10.1177/0309364612437904 22.major mj, fatone s, roth ej. validity and reliability of the berg balance scale for community-dwelling persons with lower-limb amputation. arch phys med rehabil. 2013;94(11):2194–202. doi: 10.1016/j.apmr.2013.07.002 https://doi.org/10.33137/cpoj.v7i1.43890 https://www.sralab.org/rehabilitation-measures/numeric-pain-rating-scale https://www.sralab.org/rehabilitation-measures/numeric-pain-rating-scale https://www.oandp.org/page/lower-limb-prosthetics-outcome-measures-toolkit-summary https://www.oandp.org/page/lower-limb-prosthetics-outcome-measures-toolkit-summary https://fadavis.com/product/physical-therapy-is-this-change-real-riddle-stratford https://fadavis.com/product/physical-therapy-is-this-change-real-riddle-stratford 9 pousett b.m, harasym c.c, rapaport m.s, richardson t, spellen j, moe d.w, et al. detecting changes in comfort, pain, and mobility over clinical milestones for individuals with lower limb loss. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.7. https://doi.org/10.33137/cpoj.v7i1.43890 canadian prosthetics & orthotics journal issn: 2561-987x detecting changes in comfort, pain and mobility pousett et al., 2024 23.miller wc, deathe a b, speechley m. psychometric properties of the activities-specific balance confidence scale among individuals with a lower-limb amputation. arch phys med rehabil. 2003;84(5):656–61. doi:10.1016/s0003-9993(02)04807-4 24.resnik l, borgia m. reliability of outcome measures for people with lower-limb amputations: distinguishing true change from statistical error. phys ther. 2011;91(4):555–65. doi: 10.2522/ptj. 20100287 25.prosthetic limb users survey of mobility (plus-mtm) version 1.2 short forms users guide [internet]. 2014; [cited 2024, sep 29]. available from: https://plus-m.org/ 26.hafner bj, morgan sj, askew rl, salem r. psychometric evaluation of self-report outcome measures for prosthetic applications. j rehabil res dev. 2016;53(6). doi: 10.1682/jrrd.2015.12.0228 27.hanley ma, jensen mp, ehde dm, robinson lr, cardenas dd, turner ja, et al. clinically significant change in pain intensity ratings in persons with spinal cord injury or amputation. clin j pain. 2006;22:25–31. doi:10.1097/01.ajp.0000148628.69627.82 28.patient-reported outcomes measurement information system 29-item profile (promis-29) v1.0. health measures. 2023; [cited 2024, sep 29]. available from: https://www.healthmeasures.net/explore-measurementsystems/promis 29.walker j, marable wr, smith c, sigurjónsson b, atlason if, johannesson ga. clinical outcome of transfemoral direct socket interface (part 2). can prosthet orthot j. 2021;4(1). doi: 10.33137/ cpoj.v4i1.36065 30.morgan sj, friedly jl, amtmann d, salem r, hafner bj, author c. a cross-sectional assessment of factors related to pain intensity and pain interference in lower limb prosthesis users. arch phys med rehabil. 2017;98(1):105–13. doi: 10.1016/j.apmr.2016.09. 118 31.casillas jm, hannequin a, besson d, benaïm s, krawcow c, laurent y, et al. walking tests during the exercise training: specific use for the cardiac rehabilitation. ann phys rehabil med. 2013; 56:561–75. doi: 10.1016/j.rehab.2013.09.003 32.anton a, legault z, dudek n. validity of the comprehensive high-level activity mobility predictor in a heterogeneous population with lower extremity amputations. pros orthot int. 2020;44(2):60– 5. doi: 10.1177/0309364619887559 33.imam b, miller wc, finlayson hc, eng jj, jarus t. incidence of lower limb amputation in canada. can j public health. 2017;108(4):374–80. doi: 10.17269/cjph.108.6093 https://doi.org/10.33137/cpoj.v7i1.43890 https://www.healthmeasures.net/explore-measurement-systems/promis https://www.healthmeasures.net/explore-measurement-systems/promis volume 6, issue 2 2023 d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e v o l u t i o n i n p r o s t h e t i c s & o r t h o t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x 1 raschke s.u. 3d printing in prosthetics, orthotics and assistive technology: myth and reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.1. https://doi.org/10.33137/cpoj.v6i2.42222 editorial 3d printing in prosthetics, orthotics and assistive technology: myth and reality raschke s.u* british columbia institute of technology, applied research make+ (retired), 3700 willingdon avenue, burnaby, canada. introduction the bcit make+ department, of which i was a part, has over two decades of experience in 3d printing in rehabilitation and health application, starting in 2001, with a canadian foundation for innovation (cfi) grant to establish the centre for rehabilitation engineering that enables (create) of which i was the principle investigator and in collaboration with dr. gary birch and the neil squire society, a not-for-profit that helped developed unique assistive technology for persons with high level spinal cord injury and continues to do so today through the makers making change program.1 the focal point of the create grant was a stratysis 3d printer to be used for prototyping assistive technology and biomedical devices.2 despite early fears expressed on the part of prosthetic and orthotic clinicians, our team was optimistic that this technology was a fit for the sector. our work with fused deposition modelling (fdm) printing in the biomedical and rehabilitation setting, with that initial 3d printer, had already given us some idea of the benefits and the limitations of the technology. our optimism was reciprocated by both commercial clients seeking our applied research experience, as well as by funding agencies. over the past 22 years we carried out a range of projects that 1) tested prosthetic sockets, including 3d printed models 2) examined prosthetic and orthotic digital production chains, either with commercial clients and as a graduate student project and 3) continued to use our 3d printers to prototype designs across a range of rehabilitation and biomedical applications. in 2011 our team had expanded with the awarding of a canada research chair, to dr. jaimie borisoff. a former post-doc of dr gary birch, whose lab provided 2 further fdm printers, plus a wider range of production tools (laser cutter, water jet cutter, etc.), funding was also included for post-doc positions and student projects. this was housed under the rehabilitation engineering (red) lab, into which create was integrated. it is this background from which i write this editorial today, which unlike my typical editorials, is a more personal one. it is based on an introduction i gave to a workshop on 3d printing assistive technology, orthotics and prosthetics3 recently hosted at bcit as part of our latest initiative: the bcit centre for applied research and innovation’s advanced additive manufacturing hub (aamtech).4 funded by the teck copper + health initiative and pacifican, the hub builds on our two decades of experience to further support practical research on the uses of additive manufacturing (am) for health applications. at the workshop, i spoke about my early research career as an orthotist in the late 1980s participating on projects at ubc’s medical engineering resource unit (meru) led by carl saunders before his spinning the technology of the university setting as vorum research. in one conversation with carl, i remember saying that what the field of prosthetics and orthotics needs is objective cad/cam systems which could create data informed designs. he said open access abstract 3d printing initially captured the public eye when mainstream media began writing about enabling the future, a volunteer network that had begun designing and 3d printing prosthetic hands. many of the stories focused on how this technology was going to disrupt the prosthetic sector. the response from prosthetists was skepticism and concern, in particular warning that 3d printed components would not be robust enough to withstand the activities of daily living. moreover, they emphasized that fit problems could potentially cause more harm than good. several years on, this issue explores currant usage and experiences with the technology in prosthetics and, to a limited extent, orthotics. citation raschke s.u. 3d printing in prosthetics, orthotics and assistive technology: myth and reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.1. https://doi.org/10.33137/cpoj.v6i2.42222 keywords prosthetics, orthotics, additive manufacturing, 3d printing, digital production chain, design, rehabilitation * corresponding author: silvia ursula raschke, phd british columbia institute of technology, applied research make+ (retired), 3700 willingdon avenue, burnaby, canada. e-mail: silvia-raschke-cpoj@online-publication.com orcid id: https://orcid.org/0000-0001-7964-4295 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.1. 2023 special issue https://doi.org/10.33137/cpoj.v6i2.42222 https://doi.org/10.33137/cpoj.v6i2.42222 mailto:silvia-raschke-cpoj@online-publication.com https://orcid.org/0000-0001-7964-4295 https://jps.library.utoronto.ca/index.php/cpoj/index 2 raschke s.u. 3d printing in prosthetics, orthotics and assistive technology: myth and reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.1. https://doi.org/10.33137/cpoj.v6i2.42222 canadian prosthetics & orthotics journal issn: 2561-987x 3d printing: myth and reality raschke s.u, 2023 (special issue) that what i was asking for was not possible due to the lack of data and understanding of the structural and mechanical properties of prosthetic and orthotic devices. while this may not have been possible at that time, his answer helped lead to my decision to pursue graduate studies and a research career. that decision was also driven by my repeated questions to my clinical supervisors of: “why make the orthosis or prosthesis this way?”. questions that were never answered with objective, evidence supported answers. much changed in the subsequent four decades. there was the development and expansion of evidence-based measures in the clinical setting in particular for lower limb prosthetics5 which set the stage for objective consideration of prosthetic components design. at the same time the patents on 3d printers began expiring, expanding availability and lowering costs making 3d printers available in the home and classroom. printers that were increasingly sophisticated. at the industrial level access to additive manufacturing technology such as metal printers and carbon fiber printers also began to improve. this evolving landscape allowed new communities of practice to emerge, who had identified gaps in the prosthetic and orthotic provision process that they believed they could bridge. some of the speakers at the aforementioned workshop have contributed to this special edition. other authors write about their experiences with practical and research experience in 3d printing in prosthetic and orthotic devices. they share, in their words, how far we have come both from the initial use of cad/cam and 3d printing in orthotics and prosthetics and its more recent explosion into the public eye a decade ago, providing a pragmatic perspective of where we are now. research into further developing additive manufacturing for this sector continues alongside active exploration of how what is developed can provide value to both patient and clinicians in the clinical setting. this is supported by ongoing research generating data on materials, biomechanical and structural engineering data from device testing projects, clinical outcome measure application research and, as it becomes more accessible, data from an amputee registry development initiative, being led by dr kenton kaufmann at the mayo clinic.6 the synergies created by the crossover between clinical and engineering research will support the development of expert models that i had been looking for almost four decades ago. conclusion authors in this issue share opportunities and obstacles faced as they engaged with 3d printing and the digitization of the sector. their experiences include the important message that 3d printers themselves do not do research or provide clinical care. they are just another tool that add capacity and capabilities, but they must be paired with skilled persons engaged in the prosthetic or orthotic design and provision process. a 3d printer on its own is of little use. what is also becoming clear is that benefits cannot be harnessed or obstacles overcome without reaching out across skills sets to work in interdisciplinary teams. it is incumbent on prosthetists and orthotists to reach out and collaborate with researchers and technology developers. this ensures that the digital production chains and innovative additively manufactured designs being developed do not leave them behind, potentially resulting in less-than-optimal service for their patient-clients. call to action in closing, i encourage the clinical readers of this special edition to being open to digital production chains and additive manufacturing processes and to actively reach out to researchers and technology developers with offers to collaborate and contribute, so that the systems being developed serve them as opposed to, in future, becoming their masters. for readers in the researcher and developer communities, i urge you to make a commitment to including prosthetists and orthotists in all stages of research to draw on their empirical knowledge in order to ensure the outcomes are comprehensive and robust. this requires both groups to go look beyond their comfort zones and learn from each others, ultimately benefiting the individuals they both groups aim to serve, those persons requiring assistive technology to maintain an active and fulfilling quality of life. acknowledgements none. declaration of conflicting interests i have no conflicts to interest to declare. sources of support none. references 1.makers making change [internet]. neil squire. [cited dec 17, 2023]. available from: https://www.neilsquire.ca/individualprograms-services/makers-making-change/ 2.update, a newsletter for the bcit community [internet]. bcit, 1999. [cited dec 17, 2023]. available from: https://atom.lib.bcit.ca/uploads/r/null/d/b/0/db065feb49bb5a018a7 195a61a41655cde526b56445047f3ed115c1a631aab7c/http___14 2.232.42.4_archives_digital_20repository_bcit_update_bcitu pdate1991-1999_bcitupdate_1999-11-30.pdf 3.jackson a. bcit news [internet]. bcit applied research, 2023. [cited dec 17, 2023]. available from: https://commons.bcit.ca/news/2023/11/applied-research-3dprinting-assistive-technology/ 4.advanced additive manufacturing technology hub [internet]. bcit. [cited dec 17, 2023]. available from: https://www.bcit.ca/applied-research/cari/advanced-additivemanufacturing-technology-hub/ 5.tan j.m, halford g.r.j, lukin m, kohler f. recommendations from the ispo lower-limb compass: patient-reported and https://doi.org/10.33137/cpoj.v6i2.42222 https://www.neilsquire.ca/individual-programs-services/makers-making-change/ https://www.neilsquire.ca/individual-programs-services/makers-making-change/ https://atom.lib.bcit.ca/uploads/r/null/d/b/0/db065feb49bb5a018a7195a61a41655cde526b56445047f3ed115c1a631aab7c/http___142.232.42.4_archives_digital_20repository_bcit_update_bcitupdate1991-1999_bcitupdate_1999-11-30.pdf https://atom.lib.bcit.ca/uploads/r/null/d/b/0/db065feb49bb5a018a7195a61a41655cde526b56445047f3ed115c1a631aab7c/http___142.232.42.4_archives_digital_20repository_bcit_update_bcitupdate1991-1999_bcitupdate_1999-11-30.pdf https://atom.lib.bcit.ca/uploads/r/null/d/b/0/db065feb49bb5a018a7195a61a41655cde526b56445047f3ed115c1a631aab7c/http___142.232.42.4_archives_digital_20repository_bcit_update_bcitupdate1991-1999_bcitupdate_1999-11-30.pdf https://atom.lib.bcit.ca/uploads/r/null/d/b/0/db065feb49bb5a018a7195a61a41655cde526b56445047f3ed115c1a631aab7c/http___142.232.42.4_archives_digital_20repository_bcit_update_bcitupdate1991-1999_bcitupdate_1999-11-30.pdf https://commons.bcit.ca/news/2023/11/applied-research-3d-printing-assistive-technology/ https://commons.bcit.ca/news/2023/11/applied-research-3d-printing-assistive-technology/ https://www.bcit.ca/applied-research/cari/advanced-additive-manufacturing-technology-hub/ https://www.bcit.ca/applied-research/cari/advanced-additive-manufacturing-technology-hub/ 3 raschke s.u. 3d printing in prosthetics, orthotics and assistive technology: myth and reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.1. https://doi.org/10.33137/cpoj.v6i2.42222 canadian prosthetics & orthotics journal issn: 2561-987x 3d printing: myth and reality raschke s.u, 2023 (special issue) performance-based outcome measures. prosthet orthot int. 2023;47(1), 13–25. doi: 10.1097/pxr.0000000000000197 6.limb loss and preservation registry [internet]. mayo clinic. [cited dec 17, 2023]. available from: https://www.mayo.edu/research/labs/motionanalysis/research/limb-loss-preservation-registry author scientific biography dr silvia raschke, phd, is an applied researcher (retired) with the british columbia institute of technology make+ group. she specializes in evaluation and product development projects in rehabilitation engineering with a focus on prosthetics and orthotics. in 2013 she and collaborator, dr. michael orendurff, phd won the thranhardt prize for their paper: "can you tell which foot is which?", the first double blind prosthetic foot evaluation that included community ambulation. she is currently involved in a diverse range of projects, including orthotic aspects of exoskeleton design, curriculum development and acting as a mentor to a team of young researchers who are doing a project examining glass ceilings in prosthetics and orthotics. she is editor-in-chief of the canadian prosthetics and orthotics journal and chair of the us veterans affairs rehabilitation research and development (rr&d) subcommittee on rehabilitation engineering and prosthetics/ orthotics. https://doi.org/10.33137/cpoj.v6i2.42222 https://www.mayo.edu/research/labs/motion-analysis/research/limb-loss-preservation-registry https://www.mayo.edu/research/labs/motion-analysis/research/limb-loss-preservation-registry all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 research article john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.37456 1 john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 research article differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study john s1*, orlowski k 2, mrkor k.u 2, edelmann-nusser j 1, witte k 1 1 department of sports science, faculty of humanities, otto von guericke university, magdeburg, germany. 2 department of computer science and media, brandenburg university of applied sciences, brandenburg an der havel, germany. introduction amputations of the lower limbs, especially transfemoral (tf) or transtibial (tt) amputations have a severe impact on the patient’s life. the irreversible loss of an extremity affects physical integrity and leads to social and psychological burdens.1 following amputation, rehabilitation programs and proper prosthetic fitting, as well as prosthetic usage, are important factors for improving the quality of life of the patients.2 the use of a prosthesis has been associated with higher physical function, gain in independence and increased self-esteem.3 the prescription of the type of prosthesis and its specified components as well as the financial coverage by health insurance are based on the expected functional mobility of the patient.4 to identify functional mobility, several classification systems exist to assign patients with lower open access volume 5, issue 1, article no.5. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: following amputation, patients with lower limb amputations (lla) are classified into different functional mobility levels (k-levels) ranging from k0 (lowest) to k4 (highest). however, k-level classification is often based on subjective criteria. objective measures that are able to differentiate between k-levels can help to enhance the objectivity of k-level classification. objective(s): the goal of this preliminary cross-sectional study was to investigate whether differences in hip muscle strength and balance parameters exist among patients with transfemoral amputations (tfa) assigned to different k-levels. methodology: twenty-two participants with unilateral tfa were recruited for this study, with four participants assigned to k1 or k2, six assigned to k3 and twelve assigned to k4. maximum isometric hip strength of the residual limb was assessed in hip flexion, abduction, extension, and adduction using a custom-made diagnostic device. static balance was investigated in the bipedal stance on a force plate in eyes open (eo) and eyes closed (ec) conditions. kruskal-wallis tests were used to evaluate differences between k-level groups. findings: statistical analyses revealed no significant differences in the parameters between the three k-level groups (p>0.05). descriptive analysis showed that all hip strength parameters differed among k-level groups showing an increase in maximum hip torque from k1/2-classified participants to those classified as k4. group differences were also present in all balance parameters. increased sway was observed in the k1/2 group compared to the k4 group, especially for the ec condition. conclusion: although not statistically significant, the magnitude of the differences indicates a distinction between k-level groups. these results suggest that residual limb strength and balance parameters may have the potential to be used as objective measures to assist k-level assignment for patients with tfa. this potential needs to be confirmed in future studies with a larger number of participants. article info received: september 17, 2021 accepted: january 5, 2022 published: january 12, 2022 citation john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.3 7456 keywords amputation, k-level, balance, transfemoral amputation, muscle strength, residual limb, static balance * corresponding author stefanie john, department of sports science, faculty of humanities, otto von guericke university, magdeburg, germany. email: stefanie.john@ovgu.de orcid id: https://orcid.org/0000-0001-6722-7195 https://doi.org/10.33137/cpoj.v5i1.37456 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i1.37456 https://doi.org/10.33137/cpoj.v5i1.37456 mailto:stefanie.john@ovgu.de https://orcid.org/0000-0001-6722-7195 2 john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 issn: 2561-987x hip muscle strength and static balance in patients with transfemoral amputations john et al., 2022 cpoj limb amputations (lla) to different mobility levels.4,5 in the united states, the medicare’s functional classification level (mfcl) distinguishes patients with lla into five functional levels ranging from k0 (lowest) to k4 (highest). this classification, which is intended to reflect the individual’s abilities to ambulate with the prosthesis, strongly influences the selection and assignment of the different prosthetic components. patients with lla classified as k2 will not have the possibility to receive high functioning prosthesis components as patients classified at k4. in germany, a similar classification system is used with the same categories as the mfcl system. the assignment into the different levels is based on the so-called profile survey sheet, in which doctors or orthopedic technicians subjectively evaluate abilities concerning functional mobility.6 as objective parameters, only the range of motion (rom) of joints of the lower extremities are documented. further objective evaluation criteria are missing. due to the relevance of k-level assignment for the patients with lla, the lack of objectivity has been recognized and 75% of orthopedic technicians would support additional objective measures to improve the subjectivity of k-level classification.7 in a recent study, sions et al. emphasized the necessity of reliable and valid objective measures to differentiate between k-level classifications.8 addressing the subjectivity of the existing k-level classification, gailey et al. were the first to develop a clinical tool, the amputee mobility predictor (amp),4 to objectively assess the patient’s functional abilities. the amp consists of 21 ambulation and balance tasks with and without prostheses, which are individually rated by an examiner using a point system. the amp was shown to have the potential to distinguish between k-levels.4,9 in two recent papers, physical performance tests were performed and tested if they are suitable measures to improve the objectivity of k-level assignment.8,10 differences between patients with lla classified as k3 and k4 were seen in the timed up and go test and the 6-minute walk test.8 in the study of beisheim et al., functional strength and dynamic balance tests were performed with patients with lla. k4classified patients showed higher functional strength and better dynamic balance when compared to participants classified as k3.10 these studies show that walking tests, as well as functional tests, may help to assign patients with lla to the different k-levels. performance in functional tests and walking tests are often associated with lower limb strength. several studies have demonstrated that patients with transfemoral amputation (tfa) have significantly reduced strength in the residual limb compared to the sound leg as well as to controls.11,12 the muscles surrounding the hip are important to stabilize the pelvis during standing and locomotion. weak hip abductors are one cause of the compensatory trunk shifting over the prosthetic side13 and poor balance performance.14 in a recent review, hewson et al. concluded that muscle strength deficits exist in lower limb prosthesis users and contribute to balance and mobility impairments.12 in patients with tfa, these strength deficits are particularly pronounced in the hip of the residual limb.12 however, no study has included standardized hip strength tests of the residual limb as possible measures for assisting to objectify k-level classification. objective evaluation methods must be tested for their suitability in assisting in k-level assignment, particularly methods that evaluate lower limb strength and balance. therefore, the goal of this preliminary study was to investigate whether there are differences in hip muscle strength of the residual limb as well as differences in static balance parameters among patients with tfa assigned to different k-levels. the authors hypothesized that participants classified at higher k-levels would demonstrate higher performance on the strength and balance tests than participants that were assigned to lower k-levels. methodology participants participants were recruited from january 2018 to september 2019 through calls and articles in official journals of amputee organizations as well as in a local newspaper. inclusion criteria were a unilateral transfemoral amputation with a post-amputation time of at least one year, an age ≥ 18 years and the current use of the prosthesis. due to the measurement setup, one further inclusion criterion was a minimum residual limb length of 15 cm. participants were excluded if the amputation was caused by diabetes mellitus, or if they had open wounds, edema, or acute pain in the residual limb. all participants gave written consent to participate in this study after being informed about the procedure and its purpose. the study was approved by the local ethics committee of the otto von guericke university magdeburg and carried out in line with the declaration of helsinki (no. of vote: 31/18 on march 19, 2018). measurement protocol for this cross-sectional study, the participants attended a single testing session, in which all measurements were conducted. measurements were performed in two institutions, university of magdeburg and university of applied sciences brandenburg, which were equipped with the same measurement systems. prior to physical performance tests, demographic and anthropometric data were collected and participants were asked to answer amputation related questions (e.g. type of prosthesis, years of using the prosthesis, and k-level assignment). the k-level assignment was obtained from medical records in https://doi.org/10.33137/cpoj.v5i1.37456 3 john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 issn: 2561-987x hip muscle strength and static balance in patients with transfemoral amputations john et al., 2022 cpoj collaboration with the respective orthopedic technician. the physical performance tests included isometric strength tests of the hip muscles of the residual limb as well as examinations of static balance. the strength assessment of the hip muscles was performed without the prosthesis whereas the static balance tests were performed with the prosthesis. maximum isometric hip strength analysis the measurement of the maximum isometric strength of the hip muscles of the residual limb was performed in a custommade diagnostic device (figure 1). this diagnostic device was built specifically for patients with lla. an individually adjustable pelvic support provides stability and safety during the measurements. the 270° rotatable base plate enables hip muscle strength diagnostics in different directions (hip flexion, extension, abduction and adduction) while participants do not need to change position within the device. an additional resting chair, which can be slid under the participants, is integrated into the device to provide relief of the standing leg between examinations. figure 1: the sensor-based diagnostic device in the overall display. for the strength measurement, participants were standing in an upright position supported by the pelvis support without the prosthesis. a neoprene brace was placed around the residual limb (figure 2). this brace served as an attachment possibility for the cuff of the hauling rope. a force transducer (hottinger baldwin messtechnik gmbh, darmstadt, germany) integrated into the hauling rope was used to measure the isometric strength at a sampling rate of 1000 hz for hip flexion, extension, abduction, and adduction in the neutral hip position (vertical position of the thigh perpendicular to the pelvis). before the measurements, participants were asked to familiarize themselves with the setup. for each motion direction, one submaximal test (pretest) and three maximum tests (main tests) were performed with one minute of rest between trials. participants were instructed to successively build up strength and pull maximally without an abrupt push. they could follow their current measured strength values live on the screen during the measurement. the maximum achieved strength value from the pretest was visualized on the screen as a threshold value and participants were verbally encouraged to exceed this in the main tests. the threshold value was readjusted after exceeding the previous threshold value to ensure that the maximum possible force value was reached within the three main tests. the distance between the greater trochanter and the point of applied force (center of the cuff) served approximately as the lever arm (figure 2). figure 2: setup for measuring strength in hip abduction in the neutral hip position. data were further processed in matlab (version 2018b, the mathworks inc., natick, ma) and filtered with a 4th order butterworth low-pass filter (5 hz). torques for each motion direction were calculated from the force and the lever arm force plate 270° rotatable baseplate pelvis support resting chair feedback pulling direction lever arm https://doi.org/10.33137/cpoj.v5i1.37456 4 john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 issn: 2561-987x hip muscle strength and static balance in patients with transfemoral amputations john et al., 2022 cpoj and normalized to the body mass of the participants. out of the three main trials for each motion direction, the trial with the highest torque was used for further analyses. the reliability of the isometric hip strength measurement of the diagnostic device had been investigated in a test-retest design before the examinations. the calculated intraclass correlation coefficients (iccs) showed values ranging from 0.85 to 0.95 for the isometric hip strength measurement (hip flexion, extension, abduction, and adduction). according to koo and li, these iccs indicate good to excellent reliability.15 these results suggest that the custom-made diagnostic device provides an environment to reliably quantify maximum isometric hip strength. balance assessment static balance was assessed in two different conditions: bipedal stance with eyes open (eo) and bipedal stance with eyes closed (ec). before generating balance data, the prosthetic socket comfort was determined with the prosthetic socket fit comfort score16 as poor socket fit might influence static balance parameters. socket score has been deemed a valid and reliable outcome measurement.16 the participants were asked to rate the comfort of their socket on a scale from 0 to 10 with 0 being the most uncomfortable and 10 being the most comfortable socket imaginable. mean comfort scores were between 7 and 8 points for all k-level groups. for the bipedal stance, subjects were instructed to stand hip-width apart on a 45x45 cm force plate (plux-wireless biosignals s.a, lisbon, portugal) with the arms hanging down at the sides and to remain as still as possible. for the eo conditions, participants were asked to focus on a fixed point at eye-level on the wall in front of them whereas for the ec condition the participants closed their eyes. prior to collecting data, participants practiced both poses for a few seconds. for safety reasons, an examiner stood near the participants during the entire familiarization and measurement period. once the familiarization period was over, two trials with a duration of twenty seconds were recorded for both conditions with a sampling frequency of 250 hz. balance data were further processed using matlab and filtered applying a 4th order butterworth low-pass filter with a 10 hz cut-off frequency. the total length of the center of pressure (cop) during the two standing conditions was computed as well as the maximum and mean deviations in mediolateral (ml) and anteroposterior (ap) directions. these cop-based measures have been used in most studies examining static balance in participants with lla.17 data analysis statistical analyses were performed using ibm spss statistics 26 (ibm spss, armonk, ny). based on the klevel assignment, participants were divided into groups. for each k-level group, descriptive statistics were determined for all anthropometric, demographic and measurement variables. due to the small sample size of participants and the unequal distribution of participants across k-levels, variables were described using the median and interquartile range (iqr: 25th percentile, 75th percentile). to detect differences between k-level groups, kruskal-wallis tests were performed for each variable. pairwise posthoc comparisons with bonferroni correction for multiple testing followed where appropriate. the significance level was set at p< 0.05. results participants twenty-two participants fulfilled the inclusion criteria and were considered for the study. all participants were able to complete all tests and were included in the data analysis. in table 1, participants’ anthropometric and demographic data are represented according to the k-level assignment. due to the small numbers of patients classified as k1 or k2, they were combined as one group. the kruskal-wallis test showed that age differed significantly between k-level groups. posthoc tests revealed that participants of the k4 group were significantly younger than the ones of the k1/2 group (p=0.03). the k4 group was not only younger on average, but also had a longer residual limb length and the amputation had not occurred as long ago as for k1/2 and k3-classified participants. table 1: anthropometric and demographic data of the participants presented as median and iqr (25th percentile, 75th percentile). k1/2 (n=4) k3 (n=6) k4 (n=12) p-value (kruskalwallis) age [yrs.] 75.0a (53.8, 80.5) 61.0 (51.0, 76.8) 51.5a (36.3, 60.8) 0.04* sex (m=male, f=female) 4 m, 0 f 4 m, 2 f 12 m, 0 f bmi [kg/m2] 28.8 (23.9, 30.1) 25.8 (23.8, 26.7) 26.6 (24.8, 30.5) 0.40 residual limb length [m] 0.22 (0.22, 0.39) 0.32 (0.26, 0.35) 0.38 (0.28, 0.43) 0.18 years since amputation [yrs.] 28.5 (3.0, 67.5) 19.0 (7.3, 35.5) 8.5 (4.3, 24.3) 0.63 *significant across groups (p<0.05) a significant difference between the k1/2 and the k4 group isometric hip strength of the residual limb the results of the hip muscle strength test of the residual limb are shown in table 2. a significant difference across k-level groups was only detected for hip flexion (p=0.04). the posthoc tests did not reveal significant differences https://doi.org/10.33137/cpoj.v5i1.37456 5 john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 issn: 2561-987x hip muscle strength and static balance in patients with transfemoral amputations john et al., 2022 cpoj between the individual groups (p>0.05). if the medians of the parameters are considered, an increase in maximum hip torque can be observed from participants classified as k1/2 to those classified as k4. differences were especially visible between the k3 and k4 groups with a mean difference of 0.97 nm/kg for hip flexion, 0.51 nm/kg for hip abduction, 0.45 nm/kg for hip extension and 0.44 nm/kg for hip adduction. a graphical representation of the data in form of boxplots is shown in figure 3. table 2: maximum hip torque presented as median and iqr (25th percentile, 75th percentile). *significant across groups (p<0.05) static balance the parameters from the examination of the static balance are presented in table 3. for neither the eo nor the ec condition, the kruskal-wallis tests revealed significant differences in the parameters across the three k-level groups (p>0.05). the descriptive analysis showed that differences in the medians were especially seen between k1/2 classified participants and the ones assigned to k4. for the eo condition, the mean and maximum deviation in ml and ap directions decreased from k1/2 to the k4 group. for the maximum deviation in ml and ap directions, a mean difference of 8 mm and 6 mm was determined between k1/2 and k4. for the ec condition, differences between groups became more evident. for the cop length, the mean difference between the k1/2 group and k4 group was 340 mm, and the mean differences of the maximum excursions in ml and ap directions were 23 mm and 20 mm, respectively. figure 4 shows an example of sway paths from one participant of the k1/2 group and one k4-classified participant in both eo and ec conditions. an increase in sway from the eo condition to the ec condition is visible for both k-groups, although the increase is considerably more pronounced for the k1/2-participant than for that of the participant of the k4 group. hip torque k1/2 k3 k4 p-value (kruskalwallis) hip flexion [nm/kg] 1.06 (0.53, 1.68) 1.21 (0.97, 1.53) 2.18 (1.39, 2.42) 0.04* hip abduction [nm/kg] 0.96 (0.41, 1.67) 1.00 (0.85, 1.09) 1.51 (0.91, 1.80) 0.32 hip extension [nm/kg] 0.73 (0.28, 1.13) 0.98 (0.93, 1.39) 1.43 (0.85, 1.63) 0.09 hip adduction [nm/kg] 0.98 (0.49, 1.38) 1.05 (0.74, 1.24) 1.49 (1.09, 1.92) 0.07 figure 3: maximum hip torque for the four movement directions of the three k-level groups. hip abduction hip flexion hip extension hip adduction t o rq u e [ n m /k g ] t o rq u e [ n m /k g ] t o rq u e [ n m /k g ] t o rq u e [ n m /k g ] k 1 / 2 k3 k4 k 1 / 2 k3 k4 k 1 / 2 k3 k4 k 1 / 2 k3 k4 https://doi.org/10.33137/cpoj.v5i1.37456 6 john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 issn: 2561-987x hip muscle strength and static balance in patients with transfemoral amputations john et al., 2022 cpoj table 3: cop parameters of the bipedal stance presented as median and iqr (25th percentile, 75th percentile). eyes open (eo) k1/2 k3 k4 p-value (kruskalwallis) cop length [mm] 292.7 (243.3, 684.4) 244.3 (192.7, 456.5) 270.5 (217.1, 343.2) 0.54 mean dev. ml [mm] 4.2 (2.2, 5.9) 3.2 (2.7, 4.8) 3.2 (1.8, 4.2) 0.79 mean dev. ap [mm] 4.7 (3.5. 6.6) 4.0 (3.5, 4.7) 3.4 (2.4, 5.3) 0.50 max. dev. ml [mm] 21.0 (11.8, 29.3) 14.7 (11.8, 19.0) 12.8 (10.4, 20.1) 0.59 max. dev. ap [mm] 24.7 (19.7, 29.7) 17.8 (16.2, 23.9) 18.8 (12.8, 23.0) 0.23 eyes closed (ec) cop length [mm] 925.0 (488.9, 1386.7) 624.5 (442.5, 993.8) 583.9 (387.7, 873.4) 0.50 mean dev. ml [mm] 8.0 (5.3, 10.2) 3.6 (2.9, 5.3) 3.4 (2.3, 7.6) 0.19 mean dev. ap [mm] 12.0 (6.5, 16.6) 9.1 (5.5, 9.9) 8.1 (5.7, 9.5) 0.41 max. dev. ml [mm] 38.0 (27.3, 47.2) 17.9 (15.4, 30.9) 15.1 (11.9, 39.9) 0.27 max. dev. ap [mm] 58.1 (35.0, 76.7) 45.1 (31.4, 48.7) 38.1 (28.1, 48. 7) 0.39 discussion in this study, examinations of hip muscle strength of the residual limb and examinations of static balance were performed in patients with tfa. the goal was to investigate whether these objective measures could differentiate between patients who were classified at different k-levels. as hypothesized, participants classified at higher k-levels performed better on the strength and balance tests than participants assigned to lower k-levels. however, statistical analyses revealed no significant differences in the parameters between the three k-level groups. while previous studies showed that participants with tfa suffer from a strength deficit of the residual limb, this is the first study that included an isometric muscle strength assessment of the hip muscles on the affected side for potential k-level distinction. strength differences were particularly visible between the k3 and the k4 group as well as between the k1/2 and the k4 group. for maximum torque, mean group differences ranged from 0.4 nm/kg to 0.9 nm/kg for hip flexion, hip abduction, hip extension and hip adduction. although not statistically significant, the magnitude of these values implies a distinction between k-level groups. -40 -30 -20 -10 0 10 20 30 40 -40 -20 0 20 40 a p c o p d is p la c e m e n t [m m ] ml cop displacement [mm] -40 -30 -20 -10 0 10 20 30 40 -40 -20 0 20 40 a p c o p d is p la c e m e n t [m m ] ml cop displacement [mm ] -40 -30 -20 -10 0 10 20 30 40 -40 -20 0 20 40 a p c o p d is p la c e m e n t [m m ] ml cop displacement [mm] -40 -30 -20 -10 0 10 20 30 40 -40 -20 0 20 40 a p c o p d is p la c e m e n t [m m ] ml cop displacement [mm] eyes open eyes closed k 1 /2 k 4 figure 4: examples of cop sway of one k1/2-participant compared to one classified as k4 in the eyes open and eyes closed condition. https://doi.org/10.33137/cpoj.v5i1.37456 7 john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 issn: 2561-987x hip muscle strength and static balance in patients with transfemoral amputations john et al., 2022 cpoj heitzmann et al. investigated maximum hip torque in a similar measurement setup and the hip torque differences between participants with tfa (k-level 2 to 4, no differentiation) and healthy participants were in the same numerical range (0.5-0.7 nm/kg) and statistically significant.11 reasons for the lack of statistical significance in our study may include the small number of participants in the k1/2 and k3 groups, the uneven distribution of participants among k-level groups and the individuality of each participant. beisheim et al. examined lower extremity strength differences between k3 and k4 classified participants with tfa applying the functional 5-times sit-tostand test and found a significant difference.10 functional strength tests were shown to have the potential to differentiate between k-levels. however, they could not explain the reasons why participants of the k3 group performed worse than those assigned to k4. muscle strength tests of isolated muscle groups of the residual limb, as performed in this study, have the advantage to identify specific muscle weaknesses. knowing the individual strength deficits are especially important for patients with lla as hip abductor strength is associated with gait deviations18 and hip extension strength has been reported as the greatest predictor of performance on the 6-minute walk test.19 as lower extremity strength of lower limb prosthesis users is linked to postural control, parameters of static balance were also investigated to find potential outcome measures that may be able to distinguish between k-levels. the statistical analyses, however, did not reveal significant differences in the parameters across the three k-level groups. concerning the medians of the parameters, participants classified as k1/2 showed greater cop length as well as greater mean and maximum sway deviations in ml and ap directions in the bipedal stance than the participants of the k3 and k4 groups. for all groups greater sway was observed in the ap than in the ml direction, which has been observed in previous studies.17 this may be explained by the missing ankle plantar and dorsiflexor muscles on the amputated leg which are relevant for stability control in the ap direction.20 in the eyes-closed condition, cop parameters increased and the differences in cop between k-level groups became larger. group differences of maximum excursions in ap and ml directions were observed up to 14 mm as well as a mean difference in cop length of 240 mm. increased cop sway due to the absence of visual input is in line with previous studies investigating patients with lla during quiet standing.14,17 the eyes-closed condition has a great effect on patients with lla as vision is especially relevant to compensate for balance impairments due to missing somatosensory feedback from the prosthetic leg.21 although not proven in this study, using a closed-eye condition in quiet standing might be a sensitive method for distinguishing between different k-levels as balance control mechanisms differ in relation to functional abilities. measures of static balance have been criticized that they cannot reflect postural demands in daily life.22 however, they may be helpful to identify weaknesses in postural control differentiated in ap or ml directions, which can be relevant for patients with lla. static balance tests could be performed in addition to dynamic balance tests, which have been shown to be suitable for k-level distinction among participants with tfa.10 several limitations have to be addressed. the major limitation is the small number of participants in each k-level group as well as the heterogeneity between groups, which may be the reason that no significant differences were detected. the groups differed in age, residual limb length and in post-amputation time, which may have affected the results of physical performance tests. therefore, generalization of the data is not possible and studies with larger and more homogeneous samples need to confirm the presented results. further, the cause of amputation was not recorded in this study except that patients who experienced lla due to diabetes mellitus were excluded. the amputation etiology may impact physical performance and should be recorded in future studies. in balance examinations, prosthetic alignment and different types of prosthetic components (socket, prosthetic knee and foot) may also affect performance and should be controlled in future studies. however, this is the first study that included participants with tfa classified as k1/k2 to find objective measures for supporting k-level classification. future studies should not only focus on differentiating between participants with lla classified as k3 and k4 but should also include participants classified as k2. conclusion this study was the first one to perform hip strength tests of the residual limb and static balance tests with participants with tfa classified at different k-levels to find parameters that may be suitable to enhance objective k-level classification. statistical analyses could not reveal any significant group differences but the value of the magnitude of the group differences detected may be relevant to differentiate between k-level groups. the results of the study suggest that residual limb strength and balance parameters may have the potential to serve as objective measures to support k-level classification but this potential needs to be confirmed by future studies with a larger number of participants. acknowledgements the authors are grateful for all participants who volunteered to participate in this study. https://doi.org/10.33137/cpoj.v5i1.37456 8 john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 issn: 2561-987x hip muscle strength and static balance in patients with transfemoral amputations john et al., 2022 cpoj declaration of conflicting interests the authors declare that they have no competing interests. author contribution stefanie john: contributed to the study concept and design, participated in data gathering, analyzed, and interpreted data, contributed to the drafting of the manuscript, read, and approved the final manuscript. katja orlowski: contributed to the study concept and design, participated in data gathering, contributed to the drafting of the manuscript, read, and approved the final manuscript. kai-uwe mrkor: participated in data gathering, contributed to the drafting of the manuscript, read, and approved the final manuscript. jürgen edelmann-nusser: contributed to the study concept and design, contributed to the drafting of the manuscript, read, and approved the final manuscript. kerstin witte: contributed to the study concept and design, analyzed, and interpreted data, contributed to the drafting of the manuscript, read and approved the final manuscript. sources of support german central innovation program for small and medium-sized enterprises for the project ‘multifunctional diagnostic device for patients of lower limb amputations’ (zf4096303ts6). ethical approval the study was approved by the local ethics committee of the otto von guericke university magdeburg and carried out in line with the declaration of helsinki (no. of vote: 31/18 on march 19, 2018). signed informed consent was obtained from all participants. references 1.horgan o, maclachlan m. psychosocial adjustment to lower limb amputation: a review. disabil rehabil. 2004; 26: 837–850. doi: 10.1080/09638280410001708869 2.webster jb, hakimi kn, williams rm, turner ap, norvell dc, czerniecki jm. prosthetic fitting, use, and satisfaction following lower-limb amputation: a prospective study. j rehabil res dev. 2012; 49: 1493–1504. doi: 10.1682/jrrd.2012.01.0001 3.schaffalitzky e, gallagher p, maclachlan m, ryall n. understanding the benefits of prosthetic prescription: exploring the experiences of practitioners and lower limb prosthetic users. disabil rehabil. 2011; 33: 1314–1323. doi: 10.3109/09638288.2010. 529234 4.gailey rs, roach ke, applegate eb, cho b, cunniffe b, licht s, et al. the amputee mobility predictor: an instrument to assess determinants of the lower-limb amputee's ability to ambulate. arch phys med rehabil. 2002; 83: 613–627. doi: 10.1053/apmr.2002. 32309 5.balk em, gazula a, markozannes g, kimmel hj, saldanha ij, resnik lj, et al. lower limb prostheses: measurement instruments, comparison of component effects by subgroups, and long-term outcomes. comparative effectiveness review: number 213. u.s. department of health and human services. 2018. (213). doi: 10.23970/ahrqepccer213 6.gkv spitzenverband. profilerhebungsbogen für die versorgung mit beinprothesen (2008) [gkv spitzenverband. profile survey form for the provision of prosthetic legs (2008)] [internet]. 2021, [cited 8 september 2021]. available from: https://www.gkvspitzenverband.de/media/dokumente/krankenversicherung_1/hilfs mittel/fortschreibungen_aktuell/2019_3/20190326_profilerhebung sbogen_produktgruppe_24_beinprothesen.pdf 7.borrenpohl d, kaluf b and major mj. survey of u.s. practitioners on the validity of the medicare functional classification level system and utility of clinical outcome measures for aiding k-level assignment. arch phys med rehabil. 2016; 97: 1053–1063. doi: 10.1016/j.apmr.2016.02.024 8.sions jm, beisheim eh, manal tj, smith sc, horne jr, sarlo fb. differences in physical performance measures among patients with unilateral lower-limb amputations classified as functional level k3 versus k4. arch phys med rehabil. 2018; 99: 1333–1341. doi: 10.1016/j.apmr.2017. 12.033 9.kaluf b. evaluation of mobility in persons with limb loss using the amputee mobility predictor and the prosthesis evaluation questionnaire mobility subscale. j prosthet orthot. 2014; 26: 70– 76. doi: 10.1097/jpo.0000000000000020 10.beisheim eh, horne jr, pohlig rt, sions jm. differences in measures of strength and dynamic balance among individuals with lower limb loss classified as functional level k3 versus k4. am j phys med rehabil. 2019; 98: 745–750. doi: 10.1097/phm. 0000000000001183 11.heitzmann dw, leboucher j, block j, günther m, putz c, götze m, et al. the influence of hip muscle strength on gait in individuals with a unilateral transfemoral amputation. plos one. 2020; 15: e0238093. doi: 10.1371/journal.pone.0238093 12.hewson a, dent s and sawers a. strength deficits in lower limb prosthesis users: a scoping review. prosthet orthot int. 2020; 44: 323–340. doi: 10.1177/0309364620930176 13.jaegers sm, arendzen jh and jongh hj de. prosthetic gait of unilateral transfemoral amputees: a kinematic study. arch phys med rehabil. 1995; 76: 736–743. doi: 10.1016/s00039993(95)80528-1 14.nadollek h, brauer s, isles r. outcomes after trans-tibial amputation: the relationship between quiet stance ability, strength of hip abductor muscles and gait. physiother res int. 2002; 7: 203– 214. doi: 10.1002/pri.260 15.koo tk and li my. a guideline of selecting and reporting intraclass correlation coefficients for reliability research. j chiropr med. 2016; 15: 155–163. doi: 10.1016/j.jcm.2016.02.012 16.hanspal rs, fisher k, nieveen r. prosthetic socket fit comfort score. disabil rehabil. 2003; 25: 1278–1280, doi: 10.1080/ 09638280310001603983 17.ku px, abu osman na, wan abas wab. balance control in lower extremity amputees during quiet standing: a systematic review. gait posture. 2014; 39: 672–682. doi: 10.1016/j.gaitpost. 2013.07.006 https://doi.org/10.33137/cpoj.v5i1.37456 https://www.gkv-spitzenverband.de/media/dokumente/krankenversicherung_1/hilfsmittel/fortschreibungen_aktuell/2019_3/20190326_profilerhebungsbogen_produktgruppe_24_beinprothesen.pdf https://www.gkv-spitzenverband.de/media/dokumente/krankenversicherung_1/hilfsmittel/fortschreibungen_aktuell/2019_3/20190326_profilerhebungsbogen_produktgruppe_24_beinprothesen.pdf https://www.gkv-spitzenverband.de/media/dokumente/krankenversicherung_1/hilfsmittel/fortschreibungen_aktuell/2019_3/20190326_profilerhebungsbogen_produktgruppe_24_beinprothesen.pdf https://www.gkv-spitzenverband.de/media/dokumente/krankenversicherung_1/hilfsmittel/fortschreibungen_aktuell/2019_3/20190326_profilerhebungsbogen_produktgruppe_24_beinprothesen.pdf 9 john s, orlowski k, mrkor k.u, edelmann-nusser j, witte k. differences in hip muscle strength and static balance in patients with transfemoral amputations classified at different k-levels: a preliminary cross-sectional study. canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.5. https://doi.org/10.33137/cpoj.v5i1.37456 issn: 2561-987x hip muscle strength and static balance in patients with transfemoral amputations john et al., 2022 cpoj 18.heitzmann dw, guenther m, becher b, alimusaj m, block j, van drongelen s, et al. integrating strength tests of amputees within the protocol of conventional clinical gait analysis: a novel approach. biomed tech (berl). 2013; 58: 195–204. doi: 10.1515/bmt-20120036 19.raya ma, gailey rs, fiebert im, roach ke. impairment variables predicting activity limitation in individuals with lower limb amputation. prosthet orthot int. 2010; 34: 73–84. doi: 10.3109/03093640903585008 20.da winter. human balance and posture control during standing and walking. gait posture. 1995; 3: 193–214. doi: 10.1016/09666362(96)82849-9 21.vrieling ah, van keeken hg, schoppen t, otten e, hof al, halbertsma jp, et al. balance control on a moving platform in unilateral lower limb amputees. gait posture. 2008; 28: 222–228. doi: 10.1016/j.gaitpost.2007.12.002 22.pardasaney pk, slavin md, wagenaar rc, latham nk, ni p, jette am. conceptual limitations of balance measures for community-dwelling older adults. phys ther. 2013; 93: 1351–1368. doi: 10.2522/ptj.20130028 https://doi.org/10.33137/cpoj.v5i1.37456 volume 6, issue 2 2023 articles in this special issue has been invited and reviewed by dr. silvia ursula raschke and dr. hossein gholizadeh. d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e vo l u t i o n i n p ro s t h e t i c s & o r t ho t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x https://jps.library.utoronto.ca/index.php/cpoj/editorinchief 1 hovorka c.f. leveraging digital workflows to transition the orthotics and prosthetics profession toward a client-centric and values-based care model. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.6. https://doi.org/10.33137/cpoj.v6i2.42221 stakeholder perspectives leveraging digital workflows to transition the orthotics and prosthetics profession toward a client-centric and values-based care model hovorka c.f1-3* 1 center for the intrepid, department of rehabilitation medicine, brooke army medical center, san antonio, tx, usa. 2 defense health agency, falls church, va, usa. 3 oak ridge institute for science and education, oak ridge, tn, usa. introduction this commentary was adapted from a presentation that was awarded best paper for advancing education at the 19th world congress of the international society for prosthetics and orthotics in guadalajara, mexico. it was also presented at the british columbia institute of technology’s center for applied research and innovation workshop regarding the use of 3-d printing and digital workflows in the o&p and assistive technology professions. it addressed the question: “how do professional o&p clinician education programs keep pace with changing technology and make informed decisions on what to include in curriculum and when? part 1 examines critical changes in healthcare and technology. part 2 summarizes key challenges to the o&p profession that hinder the value of care. finally, part 3 proposes a solution that leverages the use of digital technologies in the o&p workflow process as a strategy to update the care delivery model to a client-centric and values-based approach and updates the role of the clinician as an o&p expert and healthcare technology manager. part 1: changes in healthcare and technology impose challenges to the o&p profession. the orthotics and prosthetics (o&p) profession can only estimate the future healthcare economic determinants and market impacts and strategically position itself for change and likely cost-cutting measures ahead. in part 1, key challenges to u.s. healthcare that impact o&p are examined. a major challenge to the u.s. healthcare system is the persistent rise in expenditures which has influenced how healthcare is provided. between 1970 and 2020, inflation-adjusted healthcare expenditures in the u.s. have risen from $300 billion to over $4 trillion and by 2030 are projected to exceed $6.7 trillion.1,2 among the many reasons for this, five are notable including: a.) the rise in an aging population, b.) increasing multimorbidity, c.) proliferation of subspecialities, d.) culture of defensive medicine, and e.) increases in price/cost for care.3-5 open access abstract the orthotics and prosthetics (o&p) profession has a history of responding to market demands in a reactive rather than proactive manner. this has created significant impacts including shrinkage in scope of practice and constraint in remuneration for professional services due to a fee-for-device third party payer system. rapid changes in technology and healthcare combined with an outdated device-centric reimbursement system are creating unprecedented challenges that threaten sustainability of the o&p profession. hence, a reassessment of the value of o&p care, and the o&p workflow process is necessary to inform an update to the value proposition and practice model for sustainability. this article reviews key factors contributing to the current state of o&p, and potential solutions involving an update in practitioner competencies, and the care delivery model (from devicecentric to client-centric and values-based). updates could be achieved by leveraging the use of digital workflows that increase efficiencies and enhance the value of clinical outcomes. eventually, these updates could enable the o&p profession to elevate the value proposition that aligns with its most important stakeholders: client-patients and third-party reimbursement agencies in a rapidly changing technology and healthcare landscape. citation hovorka c.f. leveraging digital workflows to transition the orthotics and prosthetics profession toward a clientcentric and values-based care model. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.6. https://doi.org/10.33137/cpoj.v6i2.42221 keywords healthcare, client-centric, valuesbased, digital workflow, digital technology, competency, curriculum, orthotics, prosthetics * corresponding author: christopher f. hovorka, phd, cpo, faaop center for the intrepid, department of rehabilitation medicine, brooke army medical center, san antonio, tx, usa. e-mail: hovorkac@gmail.com orcid id: https://orcid.org/0000-0002-7147-3134 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.6, 2023 special issue https://doi.org/10.33137/cpoj.v6i2.42221 https://doi.org/10.33137/cpoj.v6i2.42221 https://orcid.org/0000-0002-7147-3134 https://jps.library.utoronto.ca/index.php/cpoj/index 2 hovorka c.f. leveraging digital workflows to transition the orthotics and prosthetics profession toward a client-centric and values-based care model. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.6. https://doi.org/10.33137/cpoj.v6i2.42221 canadian prosthetics & orthotics journal issn: 2561-987x leveraging digital workflows to transition the o&p profession hovorka c.f, 2023 (special issue) a.) rise in an aging population recently, the share of the u.s. population age 65 and over has risen to 16% and is projected to reach 20% by 2030.6 this is significant because aged persons over 65 spend more on healthcare than any other age group, hence growth in the number of older americans is expected to increase total healthcare costs over time.7,8 concomitantly, medicare spending is projected to double over the next 30 years relative to the size of the economy.3 b.) increasing multimorbidity over the past two decades, the u.s. population has experienced earlier onset of multimorbidity (>2 chronic diseases or medical conditions) which is associated with adverse health outcomes.5,9-12 in particular, the increase in multimorbidity burden has seen significant increases in cardiovascular, metabolic, endocrine, orthopedic, and behavioral disorders. over the past decade, the onset of multimorbidity in the u.s. has occurred at comparatively younger ages beginning in midlife (e.g., persons aged between 40-50 years) resulting in an increasingly complex combination of conditions similar to older adults.11,12 this contributes to substantial costs for patients and health care systems. for rehabilitation professionals, the dramatic rise in prevalence of multimorbidity, particularly obesity,13,14 cardiovascular disease, diabetes, arthritis, and cancer 15 create challenges in the complexity of client-patient assessment and treatment due to the number of overlapping body systems influenced by these conditions.16,17 adding to the complexity of care are emerging epidemics in opioid addiction and mental health disorders.18 c.) proliferation of subspecialities in 2010, nearly 65% of physicians practiced in non-primary care subspecialties and the number of subspecialists is projected to grow an additional 21% by 2025.19 this is due in part to the increasing number and complexities of clientpatients with multimorbidity. the proliferation of non-primary care subspecialists has produced a gap in primary care providers which is progressively being filled by nurse practitioner and physician assistant and expansion of their scope of practice.19,20 substantial growth in non-physician providers is projected to increase to 43% of all non-primary care subspecialists by 2025.19 the impacts of these trends on o&p may influence the accuracy in referrals for o&p services as formal training and education in o&p for physicians, nurse practitioners and physician assistants is minimal.21-23 d.) culture of defensive medicine the practice of defensive medicine – a strategy of healthcare provision to adhere to standards of care in addition to reducing risk of litigation has contributed to redundancies in care delivery. this has been associated with a proliferation of diagnostic tests and other redundancies and inefficiencies in the care delivery process24 and may be associated with the decline of primary care physicians.4,5 these redundancies and inefficiencies contribute to increases in the costs for healthcare. e.) increases in price/cost for care increases in the price/cost for healthcare are due to a multitude of factors including those previously discussed that create a culture of fragmentation of care due to the multitude of subspecialist care providers delivering overlapping services with limited collaboration and communication.1,16,17,25-27 given the persistent rise in healthcare expenditures and costs, is not surprising that alternative strategies and care delivery models are emerging as cost containment strategies,27 these strategies will be covered in part 2. part 2: u.s. healthcare is transitioning toward clientcentric and values-based care. client-centric and values-based care is part of a larger u.s. national quality strategy to reform how healthcare is delivered and reimbursed.28 the end goal of this approach is that third party payers incentivize and reimburse health care professionals for quality rather than quantity of services they provide.29 in o&p, the traditional devicecentric model of care may minimize the wider value proposition for client centric and values-based care. the fee-for-device model of care in o&p not only constrains the economic sustainability of o&p provision of care, but it also erodes the value proposition by neglecting the impact on the client-patient’s function and wellbeing. this is a major challenge for the o&p profession because it hinders the o&p profession in providing what reimbursement agencies want to know regarding the value of o&p service to the client-patient that answers key questions such as: •how effectively does o&p service provision meet the client-patient’s values, needs and goals? •how effectively does o&p service provision improve the client-patient’s health and reduce their disability including the costs for healthcare? u.s. o&p masters curriculum guidelines are device (not client) centric academic programs training o&p clinicians can influence the quality and capabilities of the workforce.30 hence, the nature of the curriculum and training influences the capabilities of graduates and their ability to adapt to market demands. but when curriculum does not address market demands, challenges to its workforce become evident. this is the case with current u.s. o&p master’s curriculum consisting of device-centric accreditation guidelines and https://doi.org/10.33137/cpoj.v6i2.42221 3 hovorka c.f. leveraging digital workflows to transition the orthotics and prosthetics profession toward a client-centric and values-based care model. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.6. https://doi.org/10.33137/cpoj.v6i2.42221 canadian prosthetics & orthotics journal issn: 2561-987x leveraging digital workflows to transition the o&p profession hovorka c.f, 2023 (special issue) standards for teaching o&p device design, manufacturing and fitting.31 content on client-centric and values-based care principles and care provision methods is limited. notable omissions in core curriculum are: a.) evaluating client-patient’s additional body systems function beyond the muscular, neurological, skeletal and integumentary systems, b.) creating and prioritizing the client-patient problem list, c.) creating / defining client-patient goals and values using systematic and measurable strategies, d.) formulating and executing evidence-based treatment plans to achieve client-patient goals and values, e.) systematically assessing treatment outcome, and f.) updating the treatment plan as changes occur over the course of the client-patient’s diseases or conditions, and g.) engagement in substantive scholarly activity. further, there are limited guidelines regarding practitioner competencies (knowledge, skills, behaviors, traits) in the following key roles including: a.) research and scholarship, leadership, collaboration, communication, professionalism; and management of healthcare technologies. recently, the national commission on o&p education (ncope) spearheaded a summit meeting to evaluate the state of u.s. o&p curriculum.32 stakeholders included were educators, accreditation agencies, clinicians and representatives from the scientific, business and credentialing agencies in o&p (e.g., ncope, american board for certification in o&p and pedorthics, american academy of o&p, american o&p association). unfortunately, other key stakeholders such as third-party payers, other healthcare and related professions (e.g., medicine, dentistry, podiatry, occupational therapy, physician assistant, nursing, engineering) and o&p technology disruptors were omitted. the goal of the meeting was to identify critical challenges to the o&p workforce and the requisite updates to curriculum needed to align the workforce for changes in technology and healthcare. preliminary findings were that the device-centric model of reimbursement hindered the practice model of care and the need to consider methods that increase efficiencies in the o&p workflow.32 part 3: leverage digital technologies that enable an update in the o&p curriculum to client-centric and values-based care. healthcare in the u.s. is moving from the traditional fee-forservice (e.g., fee-for-device in o&p) and volume-based reimbursement to one that is value based, due to national mandates.33 in order to improve value in health care delivery, we must improve the education for those providing health care.34 in orthotics and prosthetics, there is opportunity to update education through strategic curriculum changes that focus on strengthening a practitioner’s skillsets in digital health technologies (i.e., data science, artificial intelligence) to enable evidencebased clinical decision-making, combined with the mastery of digital shape capture and additive manufacturing processes to improve efficiencies in the o&p workflow. by doing so, future o&p clinicians could solidify their role.30 strategic implementation of digital health technologies (including 3-d shape capture, 3-d printing) has shown promise in improving efficiencies in the o&p manufacturing workflow compared to traditional artisanal workflow methods which require specific skills of the craft including substantial capital investment such as large overhead costs for production, machinery, equipment and skilled labor35 (figure 1). figure 1: comparison of workflow processes in orthotics and prosthetics. typical artisanal workflow (top image) and digital workflow (bottom image). 3 scanning d ig it l 3 igital ectification 3 printing digit l or shop cast impression taking create positive model ectify positive model thermoforming laminating trimming & inishing t p ic l t pic l ph sic l nuf cturing or shop https://doi.org/10.33137/cpoj.v6i2.42221 4 hovorka c.f. leveraging digital workflows to transition the orthotics and prosthetics profession toward a client-centric and values-based care model. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.6. https://doi.org/10.33137/cpoj.v6i2.42221 canadian prosthetics & orthotics journal issn: 2561-987x leveraging digital workflows to transition the o&p profession hovorka c.f, 2023 (special issue) the digital workflow has the potential to enable efficiencies in time, resources and costs compared to the typical artisanal workflow process. specifically, there is potential for digital workflow to improve efficiencies in the design and manufacturing process in o&p as these methods are innovative and highly scalable utilizing less subjective, more reproducible and potentially cost-effective methods.36 advances in digital technology keep transforming healthcare, and from a training and education perspective these technologies have the advantage of providing more reliable feedback than traditional artisanal methods.30,37-40 specifically, 3-d digital shape and rectification technologies can be used to characterize and quantify student competencies in executing task-specific methods in clientpatient functional assessment and in the design and manufacturing process.38 historical logs that quantify student performance in achieving milestones for shape capture, rectification and manufacturing quality can be quantified and characterized using digital records whereas traditional artisanal methods are less reliable and more subjective. hence digital technologies can leverage new opportunities to target student learning and retention.41 as such, the potential for digital technologies to add utility and workflow efficiency creates opportunity to update other key elements of curriculum and education. this is discussed in the next section. framework 1: canmeds client-centered practitioner training and education of clinical care providers requires that students achieve a level of competence in knowledge, skills, abilities, and traits and demonstrating these safely and effectively within a scope of practice. measuring competence is essential for determining the ability and readiness of healthcare professionals to provide quality services.42 because the o&p master’s curriculum guide lists curricular topics and device-specific standards, a proposed competency-based framework that clearly identifies roles of the practitioner that enable service delivery could address gaps in content and conceptual framework of an o&p practitioner with transferrable knowledge, skills, abilities, and traits. a practitioner framework known as the canadian medical education directives for specialists (canmeds) provides a practitioner competency framework developed by the royal college of physicians and surgeons and contains many elements that can be adapted to the roles and competencies of an o&p practitioner.43-45 the canmeds is a set of competencies that are grouped thematically into seven roles (health advocate, communicator, collaborator, leader, scholar, professional and medical expert) deemed essential for effective healthcare provision. the framework is used for the education of physicians in canada and is aimed at enhancing client-patient care and has been recognized globally. each role is subdivided into key competencies that describe the knowledge, skills, abilities and traits in measurable and relevant elements that can be used to gauge student learning. therefore, the canmeds practitioner framework provides a competency-based teaching structure that has the potential for more targeted and measurable learning outcomes. figure 2: modified canmeds practitioner framework for orthotists and prosthetists. the original practitioner framework created by the royal college of physicians and surgeons was modified for o&p by updating the roles from “medical expert” and ‘healthcare advocate” to “o&p expert” and “technology management”. image adapted from the canmeds physician competency diagram with permission of the royal college of physicians and surgeons of canada. the canmeds framework can be adapted to the o&p clinical practitioner and scope of practice by replacing the roles of “medical expert” to “o&p expert” and “health advocate” to “technology management” (figure 2). these updates expand the o&p scope of practice for adapting to changes in technology and healthcare. the technology management role expands the o&p practitioner competency for adapting to changes in technology.45 the o&p expert is the integrator role that further expands the o&p practitioner competency required for managing the values, needs and priorities of the clientpatient as well as other stakeholders such as the referral source and third-party payers. hence, the role of o&p expert requires the integration of all other roles (e.g., scholar, communicator, collaborator, professional, leader, technology management). as such, the revised o&p practitioner framework broadens the roles that includes medical-clinical focus and guidance of client-patients in navigating the increasing number of technology options.44,45 professional communicator collaborator leader scholar o&p expert technology management https://doi.org/10.33137/cpoj.v6i2.42221 https://www.royalcollege.ca/en/canmeds/about-canmeds.html https://www.royalcollege.ca/en/canmeds/about-canmeds.html 5 hovorka c.f. leveraging digital workflows to transition the orthotics and prosthetics profession toward a client-centric and values-based care model. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.6. https://doi.org/10.33137/cpoj.v6i2.42221 canadian prosthetics & orthotics journal issn: 2561-987x leveraging digital workflows to transition the o&p profession hovorka c.f, 2023 (special issue) two additional complimentary curricular frameworks (icf and pop) are needed to address demands on the o&p clinician for the provision of client-centric and values-based care that includes the client-patient in decision making. one framework (icf) is needed for clinician thoroughness by employing the international classification of functioning, disability and health (icf) and another framework (pop) is needed for clinician efficiency by employing the prosthetic orthotic process. framework 2: icf client-centric and values-based care provision the international classification of functioning, disability and health (icf)46-48 is a framework for understanding the “whole” client using a broader perspective. the ic views function and disability as an interaction between the person and his/her/their world (figure 3). it is used as a clinical practice framework for o&p professionals to develop more informed client-centric and values-based perspectives. the approach has been implemented globally in o&p in australia, europe and india.49-52 it encourages the o&p practitioner to consider additional factors in the plan of care as part of a more comprehensive and holistic biopsychosocial perspective. figure 3: international classification of functioning, disability and health. adopted from icf, geneva, switzerland, world health organization, 2001; license cc by-nc-sa 3.0 igo framework 3: pop client-centric and values-based care provision the prosthetic and orthotic process (pop) is a service delivery framework that adapts the icf to clinical o&p processes (figure 4).52 using this approach, the clientpatient’s goals related to activities are realized by an o&p treatment plan. this method utilized by the o&p professional, enables the client-patient to achieve goals related to body functions and structures. it consists of four steps in a cycle: 1.) assessment (including medical history and physical examination/review of systems of the clientpatient. 2.) goals, specified on four levels including those related to participation, activity, body functions and structures and technical requirements of the o&p technologies. 3.) intervention, in which the appropriate course of action is determined based on the specified goal and evidence-based practice. 4.) evaluation of outcomes, where the outcomes are assessed and compared to the corresponding goals. after evaluation of goal fulfillment, a broad evaluation is then made including questions about the client-patient’s satisfaction with the outcomes and the process. this evaluation determines if the process is ended or if another cycle in the process should be initiated.52 call to action increasing costs of care and the need for cost cutting, the complexity of healthcare, and advances in technology, continue to challenge the o&p profession. there is an opportunity to proactively address gaps in the o&p master’s curriculum that omit the wider scope of competencies to manage client-patients for client-centric and values-based care. these gaps could be addressed by including the modified canmeds competency-based framework to enhance the knowledge, skills, abilities and traits of the o&p practitioner. two complimentary practice frameworks (icf and pop) can further enable o&p practitioners to overcome increasing demands for thoroughness and efficiency required in modern healthcare by leveraging the use of digital technologies to improve efficiencies in the o&p workflow. hence, the three frameworks can inform a more comprehensive approach for o&p client-centric and valuesbased care. transition of the proposed new curriculum has the potential to more effectively enable o&p clinicians to address the client-patient’s values and priorities and select the optimal combination of technologies that meet client-patients’ needs and to deliver the wider value proposition. moreover, a modernized and reconceived practitioner as o&p expert and healthcare technology manager that directs greater attention to client-centric and values-based care would be able to distinguish themselves as a unique and valuable professional asset as an interdisciplinary health care team member. therefore o&p education transition is crucial to the evolution of the profession, especially considering unprecedented challenges ahead. health condition (disorder or disease) participation activities body functions and structures environmental factors personal factors https://doi.org/10.33137/cpoj.v6i2.42221 6 hovorka c.f. leveraging digital workflows to transition the orthotics and prosthetics profession toward a client-centric and values-based care model. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.6. https://doi.org/10.33137/cpoj.v6i2.42221 canadian prosthetics & orthotics journal issn: 2561-987x leveraging digital workflows to transition the o&p profession hovorka c.f, 2023 (special issue) acknowledgements the author acknowledges ben lucas, mspo, cpo who contributed to this paper by sharing his perspectives regarding the canmeds and icf frameworks from the lens of a clinician and educator; silvia raschke, phd, co(c) who shared her perspectives regarding a proposed technology management competency in the o&p practitioner framework from prior o&p future scan and workforce needs analyses; and kristin carnahan, mspo, cpo, faaop and kari pichora, mspo, cpo who shared their perspectives as clinician educators. declaration of conflicting interests the views expressed herein are those of the author and do not reflect the official policy or position of the brooke army medical center, the department of defense, defense health agency, or any agencies under the u.s. government. sources of support no grants or support. the author was employed as a member of the faculty at midwestern university, glendale, az, usa during a portion of development of the three curricular frameworks. references 1.peterson kff. how has u.s. spending on healthcare changed over time? [internet]. health system tracker. 2022; [cited 2023 nov. 23]. available from: https://www.healthsystemtracker.org/chart-collection/us-spending-healthcare-changedtime/#total%20national%20health%20expenditures,%20us%20$%20 billions,%201970-2020 2.cms office of the actuary releases 2021-2030 projections of national health expenditures [internet]. centers for medicare & medicaid services. 2022; [cited 2023 nov. 25]. available from: https://www.cms.gov/newsroom/press-releases/cms-officeactuary-releases-2021-2030-projections-national-healthexpenditures 3.why are americans paying more for healthcare? [internet]. peter g. peterson foundation. 2023; [cited 2023 sep. 10]. available from:https://www.pgpf.org/blog/2023/07/why-are-americanspaying-more-for-healthcare accessed on 10/6/23 4.specialty profiles [internet].careers in medicine. 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[cited 2023 nov. 23]. available from: https://www.royalcollege.ca/rcsite/canmeds/canmeds-framework-e 44.hovorka cf. o&p education: guiding the transition to clientcentric training [internet]. the o&p edge. 2022; [cited 2023 nov. 23]. available from: https://opedge.com/op-education-guiding-thetransition-to-client-centric-training/ 45.raschke s. technology management as a core component of a client-centric prosthetic orthotic practice model. can prosthet orthot j. 2022:5;2:1. doi:10.33137/cpoj.v5i2.39001 46. international classification of functioning, disability and health (icf) [internet]. world health organization, geneva; who, 2001; [cited 2023 nov. 23]. available from: https://www.who.int/standards/classifications/internationalclassification-of-functioning-disability-and-health 47.international classification of functioning, disability and health: children and youth version: icf-cy [internet]. world health organization, geneva; 2007; [cited 2023 nov. 23]. available from: https://www.google.com/books/edition/international_classification _of_function/swfqdxyurcc?hl=en&gpv=1&pg=pr5&printsec=frontcover 48. allan cm, campbell wn, guptill ca, stephenson ff, campbell ke. a conceptual model for interprofessional education: the international classification of functioning, disability and health (icf). j interprof care. 2006; 20(3):235-45. doi: 10.1080/ 13561820600718139 49.goertzen jjb, rommers gm, dekker r. an icf-based education programme in amputation rehabilitation for medical residents in the netherlands. prosthet orthot int. 2011:35(3):31822. doi:10.1177/0309364611412822 50.radhakrishnan s, kohler f, gutenbrunner c, jayaraman a, pieber k, jianin l, schiappacasses c. mobility in persons with lower extremity amputations and influencing factors: using the international classification of functioning, disability and health to quantify expert views. prosthet orthot int. 2018:43(1):88-94. doi: 10.1177/0309364618792714 51.clarke l, ridgewell e, dillon mp. identifying and linking prosthetic outcomes to the icf framework: a step to inform the benefits measured in prosthetic health economic evaluations. disabil rehabil. 2023:45(6):1103-1113. doi:10.1080/09638288. 2022.2049902 52.jarl g, ramstrand n. a model to facilitate implementation of the international classification of functioning, disability and health into prosthetics and orthotics. prosthet orthot int. 2018:42(5):468-475. doi: 10.1177/0309364617729925 author scientific biography christopher f. hovorka, phd, cpo, lpo, faaop. dr. hovorka completed bachelor’s degrees in exercise science (university of new mexico) and prosthetics and orthotics (university of washington), clinical residencies in orthotics (southern illinois university school of medicine) and prosthetics (connecticut children’s medical center, formerly newington children’s hospital), a master’s degree in allied health science (university of connecticut) and phd in applied physiology with focus in biomechanics and neuromotor control (georgia tech). he held faculty appointments at the university of texas southwestern medical center, st. ambrose university, georgia tech, university of pittsburgh, east tennessee state university and midwestern university. he has received continuous research grant funding for over 20 years, in areas ranging from cognitive / skills learning and curriculum development to the neuromechanics and clinical outcomes of persons using lower limb prostheses, orthoses and footwear. he also developed the nation’s first accredited entry-level master’s degree in orthotics and prosthetics (o&p) at georgia tech. creation of that program sparked a national reassessment of the entry-level standards in o&p, and eventually adoption of the master’s degree as the entrylevel standard for o&p in the united states. currently, he is an established scientist fellow at the center for the intrepid, department of rehabilitation medicine, brooke army medical center, san antonio, tx, usa and is affiliated with the defense health agency, falls church, va, usa and oak ridge institute for science and education, oak ridge, tn, usa. https://doi.org/10.33137/cpoj.v6i2.42221 https://www.royalcollege.ca/rcsite/canmeds/canmeds-framework-e https://opedge.com/op-education-guiding-the-transition-to-client-centric-training/ https://opedge.com/op-education-guiding-the-transition-to-client-centric-training/ https://www.who.int/standards/classifications/international-classification-of-functioning-disability-and-health https://www.who.int/standards/classifications/international-classification-of-functioning-disability-and-health https://www.google.com/books/edition/international_classification_of_function/swfqdxyu-rcc?hl=en&gpv=1&pg=pr5&printsec=frontcover https://www.google.com/books/edition/international_classification_of_function/swfqdxyu-rcc?hl=en&gpv=1&pg=pr5&printsec=frontcover https://www.google.com/books/edition/international_classification_of_function/swfqdxyu-rcc?hl=en&gpv=1&pg=pr5&printsec=frontcover all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 6, issue 1 2023 research article smith jd, guerra g, symons tb, kwon eh, yoon ej. comparison of body composition methods for estimating body fat percentage in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.2. https://doi.org/10.33137/cpoj.v6i1.41605 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v6i1.41605 1 smith jd, guerra g, symons tb, kwon eh, yoon ej. comparison of body composition methods for estimating body fat percentage in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.2. https://doi.org/10.33137/cpoj.v6i1.41605 research article comparison of body composition methods for estimating body fat percentage in lower limb prosthesis users smith jd1, guerra g2 *, symons tb1, kwon eh1, yoon ej2, 3 1 department of counseling, health and kinesiology, college of education and human development, texas a&m universitysan antonio, san antonio, texas, usa. 2 department of exercise and sport science, st. mary’s university, san antonio, texas, usa. 3 laboratory of animal physiology and medicine, department of biology education, korea national university of education, chungbuk, republic of korea. introduction in the united states over forty percent of individuals are considered obese.1 persons with a higher percentage of body fat are at greater risk of negative cardiometabolic health.2,3 likewise, higher body mass index (bmi) may increase susceptibility to coronary heart disease and type 2 diabetes,4–6 and increase medical expenses.7,8 there is also evidence that individuals who are obese may suffer from lowered wages and education.9 prevalence of obesity may be higher in persons with lower limb amputation (lla) than in able-bodied persons,10–12 with higher bmi typically seen at higher amputation levels (i.e. trans-femoral).13,14 for those having received dysvascular-related amputations, loss of adequate blood flow to the peripheries, negatively alters limb musculature and fat mass.15,16 most people receive amputation as a result of dysvascular disease and it is these individuals that are often overweight with a bmi ≥ 25 kg/m2 or even obese with a bmi ≥ 30 kg/m2.17,18 although bmi is simple to calculate, body fat percentage (bf%) provides a better indicator of health risk.19 a closer analysis of limb composition in people with amputation has found greater muscle atrophy and fat mass (fm) in the amputated limb.20 obesity is associated with dysvascular disease, which accounts for a majority of lower extremity amputations in the united states, thus, valid body composition assessment is essential. open access abstract background: there is a dearth of literature evaluating the accuracy of air displacement plethysmography (adp) compared to dual-energy x-ray absorptiometry (dxa) for assessing body composition in individuals with lower limb amputations. validity of adp in persons with lower limb amputations must be established. objective: the objective of this study was to compare body composition in persons with lower limb amputations using the bod pod® and dxa. methodology: body composition was performed on eleven lower limb prosthesis users (age 53.2±14.3 years, weight 81.9±22.3kg) using adp and dxa with and without prosthesis. findings: repeated measures anova indicated no significant difference in body composition among and between trials, f(3,8)= 3.36, p= 0.075. there were no significant differences in body fat (bf) percentage with and without prostheses on the bod pod (28.5±15.7% and 33.7±12.1%, respectively) nor the dxa (32.9±10.6% and 32.0±9.9%, respectively). association between the bod pod and dxa were greatest when prostheses were not worn compared to when they were worn. bland-altman plots indicate agreement between bod pod® and dxa was greatest while wearing the prosthesis. conclusion: this study is a first to compare total body fat percent between the bod pod® and dxa in lower limb prosthesis users. bod pod® report valid indices of bf%. future work will utilize the bod pod® in intervention studies for monitoring body composition changes across the continuum of rehabilitation. article info received: august 28, 2023 accepted: october 23, 2023 published: november 10, 2023 citation smith jd, guerra g, symons tb, kwon eh, yoon ej. comparison of body composition methods for estimating body fat percentage in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.2. https://doi.org/10.33137/cpoj.v6i1.4 1605 keywords body composition, prosthesis, dxa, adp, air displacement plethysmography, dual-energy xray absorptiometry, body fat, amputation * corresponding author: gary guerra, phd department of exercise and sport science, st. mary’s university, san antonio, texas, usa. email: gguerra5@stmarytx.edu orcid id: https://orcid.org/0000-0002-0161-4616 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 1, article no.2. 2023 https://doi.org/10.33137/cpoj.v6i1.41605 https://doi.org/10.33137/cpoj.v6i1.41605 https://doi.org/10.33137/cpoj.v6i1.41605 mailto:gguerra5@stmarytx.edu https://orcid.org/0000-0002-0161-4616 https://jps.library.utoronto.ca/index.php/cpoj/index 2 smith jd, guerra g, symons tb, kwon eh, yoon ej. comparison of body composition methods for estimating body fat percentage in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.2. https://doi.org/10.33137/cpoj.v6i1.41605 canadian prosthetics & orthotics journal issn: 2561-987x body composition methods for estimating body fat percentage smith et al., 2023 a variety of commercial and research grade tools exist for measuring body composition.21 bioelectrical impedance analysis (bia) is inexpensive, portable and non-invasive.22 despite bia being validated and used in research,23–25 error of 9.79% has been seen when compared to dual-energy xray absorptiometry (dxa).26 the dxa offers precise estimates of body fat free mass (ffm),27 but its high cost and radiation exposure makes routine use prohibitive. air displacement plethysmography (adp) is not as costly as dxa and requires limited training to administer.25 there is a dearth of literature comparing total bf% from adp to dxa in persons with lower limb amputations. those that have explored validation have found that adp can overestimate bf% in thinner individuals and underestimate bf% in heavier persons.28 for body composition assessment to become a routine outcome measurement, time and resources must be considered.29 adp may be widely utilized, however, its validity in persons with lower limb amputations must still be established. the purpose of this study was to evaluate body composition as measured by adp when compared to dxa in persons with lower limb amputations. since there are a lack of studies that compare percent body fat of those with lower limb amputations using adp and dxa, 1) it was hypothesized there would be no significant difference in percent body fat between adp and dxa and 2) it was also hypothesized there would be no significant difference in percent body fat when wearing and not wearing prosthesis. methodology participants this study was approved by the texas a&m university san antonio institutional review board (log#2020-69) and all participants signed an informed consent form before study commencement. eleven persons with limb amputations participated in this study (table 1) and were recruited in san antonio, tx through local support groups and clinics. the selection criteria included any person with a lower limb amputation who could ambulate on a prosthesis with or without an assisted device, and excluded those who might be pregnant. this sample size reflects that of other studies utilizing dxa as a measure of body composition.30–33 all participants were asked to not eat a heavy meal four hours prior to testing, abstain from exercise, and maintain appropriate hydration prior to data collection. height was measured while wearing prostheses and no shoes to the nearest 0.1 cm using a stadiometer (seca 213, hamburg, germany). body mass was measured to the nearest 0.1kg using a digital scale (bod pod®, cosmed, usa inc., concord, ca, usa). body mass index was determined by weight divided by stature squared (kg/m2). assessments were performed by trained professionals with university employment and all measurements were carried out according to manufacturer instructions. measurements participants reported on two separate days and prior to measurement, were asked to empty their bladder. the adp body volume measurement was conducted using a bod pod® (cosmed usa inc., concord, ca, usa). a warmup, calibration and weight scale calibration were performed before testing according to the manufacturer guidelines. participants removed all jewelry and wore tight-fitting garments (swimsuits, yoga pants, etc.) and swim cap to reduce air trapped in clothing and hair. body mass was measured using the bod pod® scale and volume determined twice. participants sat quietly and breathed normally while seated in the bod pod®. the measurement procedure was repeated once again after doffing the prosthesis. the cosmed software’s siri equation was chosen for measurements of bf%.34,35 whole body dxa measurement occurred immediately after the bod pod® measurement using a lunar prodigy (ge medical systems, chicago, il). before measurement, the dxa was calibrated according to manufacturer guidelines. participants wore the same minimal tight-fitting clothing worn during bod pod® measurements and the same investigator performed and analyzed each scan. participants were asked to lay supine with limbs oriented by their sides, once with the prosthesis and once again without wearing prosthesis. this procedure took 20-30 minutes and once complete, participants were scheduled for their second session, which took place approximately one week later. statistical analysis analysis was performed using spss version 27 (ibm corp, armonk, ny). a repeated measures anova was performed to explore differences in body composition among and between the trials, a method commonly used to make these types of comparisons (cite).36–40 bland and altman plots were created to assess the agreement between the two body composition methods. pearson’s product moment correlations were performed to determine relationships between the two methods, with 0.20-0.39 being weak, 0.400.59 being moderate, 0.60-0.79 being strong, and >0.80 being very strong.41 cronbach’s alpha was used as a measure of internal consistency with 0.90 or greater considered high agreement; 0.80 to 0.89, moderate agreement; and 0.79 or lower, low agreement42 alpha of 0.05 was used for all statistical testing. results table 1 provides participant demographics and prosthesis type. results of repeated measures anova on body composition among and between trials were not significant, f(3,8)= 3.36, p= 0.075. while there was a trend for bf% measured by the bod pod to be lowest with the prosthesis https://doi.org/10.33137/cpoj.v6i1.41605 3 smith jd, guerra g, symons tb, kwon eh, yoon ej. comparison of body composition methods for estimating body fat percentage in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.2. https://doi.org/10.33137/cpoj.v6i1.41605 canadian prosthetics & orthotics journal issn: 2561-987x body composition methods for estimating body fat percentage smith et al., 2023 (28.5±15.7%) and highest without it (33.7±12.1%), measurements by the dxa for both with (32.9±10.6%) and without (32.0±9.9%) fell between those parameters (figure 1), none of which were significant. it is worthy to note, however, that the effect size for bod pod® (cohen’s d = 0.71) is moderate compared to dxa (cohen’s d = 0.32), which is weak.43 bland-altman analysis indicated mean difference and 95% limits of agreement (loa) between the bod pod® and dxa was greatest when wearing prostheses (mdiff = -4.38, 95% loa = -27.4 18.7) compared to not wearing the prostheses (mdiff = 1.73, 95% loa = -11.5 14.9), figure 2. table 1: participant characteristics mean±sd. figure 1: there were no significant differences in percent body fat between bod pod® and dxa when wearing and not wearing prostheses, p > 0.05. note: individual data points are participant data points for bod pod® and dxa with and without prosthesis. table 2 provides a correlation matrix depicting the relationships of the measures, all of which were significant at 0.05. the highest pearson correlations between the bod pod® and dxa were observed between devices when prostheses were not worn compared to when they were worn (figure 3). similarly, internal consistency was greatest between the two instruments while not wearing prostheses (cronbach’s alpha = 0.901) compared to wearing them (cronbach’s alpha = 0.772). figure 2. tighter limits of agreement exist between the bod pod® and dxa when not wearing prostheses. figure 2: tighter limits of agreement exist between the bod pod® and dxa when not wearing prostheses. note: solid line represents mean difference and dashed lines represent 95% limits of agreement. table 2: correlations of percent body fat from bod pod® and dxa with and without prostheses. bod pod® with bod pod® without dxa with bod pod® without 0.89* dxa with 0.68* 0.87* dxa without 0.63* 0.84* 0.97* note: *p < 0.05 discussion in this study we compared bod pod® derived body fat percent estimates to dxa estimates in persons with lower limb prosthesis. we found that bod pod® estimates were not significantly different to dxa estimates whether prosthesis was worn or not. the bod pod® n=11 amputation level age (yrs) 53.2±14.3 below knee 8 height (cm) 170.7±9.2 above knee 1 weight (kg, with prostheses) 84.7±21.8 bilateral below knee 1 weight (kg, without prostheses) 81.9±22.3 other* 1 bmi (with prostheses) 28.9±6.1 bmi (without prostheses) 27.8±6.2 *note: other is right hip disarticulate and left below knee. bod pod bod pod dxa dxa with prosthesis without prosthesis b o d y f a t p e rc e n ta g e ( % ) (b o d p o d d x a ) (b f % ) with prosthesis (bod pod + dxa)/2 (bf%) without prosthesis (bod pod + dxa)/2 (bf%) (b o d p o d d x a ) (b f % ) https://doi.org/10.33137/cpoj.v6i1.41605 4 smith jd, guerra g, symons tb, kwon eh, yoon ej. comparison of body composition methods for estimating body fat percentage in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.2. https://doi.org/10.33137/cpoj.v6i1.41605 canadian prosthetics & orthotics journal issn: 2561-987x body composition methods for estimating body fat percentage smith et al., 2023 underestimated body fat percentage compared to dxa when wearing the prosthesis by 13.1% (difference of 4.3%) and overestimated without the prosthesis 5% (difference of 1.7%), respectively. figure 3: relationships of percent body fat from bod pod® and dxa with and without prosthesis. note: there was a stronger association in percent body fat between bod pod® and dxa when not wearing prostheses (r(9) = 0.87, p = 0.001) compared to wearing it (r(9) = 0.68, p = 0.02) during measurements. the (9) represents the degrees of freedom. some studies have observed divergences of –3.0% to 1.7%,44 while others have observed 1.6% overestimates of bf% for bod pod® over dxa %bf. still, the novelty of our study is our finding of similar measures of bod pod® and dxa in lower limb prosthesis users. the instruments compared in our study have been compared in the general population,45 persons with diabetes and obesity,46 and even wheelchair sport users.47 the differences observed between the bod pod® and dxa may be a result of the bod pod® using a siri 2-compartment model of fat and lean mass to calculate body fat percentage. the siri densiometry formula estimates body fat from body density. this formula has been shown to overestimate bf% is nonobese active individuals,48 as well as individuals that are obese.49 as the body contains other tissues such as water, connective, and bone, distinguishing bone density is possible with dxa, which may help reduce variances. however, it is unclear at this time if specific formulas to assess body fat percentages in persons with lower limb amputations are required. the bod pod® is a suitable alternative to dxa as it places low burden on the prosthesis user, less expensive, simple to perform, and no need for radiation safety measures. greater agreement between the two measures as evidenced by tighter limits in the bland-altman plots suggest doffing the prostheses when assessing body composition. this is consistent with measures of internal consistency as calculated by cronbach’s alpha. furthermore, while the relationship between bf% when wearing the prostheses was moderately strong, doffing the prostheses produced the strongest relationship between the two measures. given this information, and since there was a ~2% difference in bf% between bod pod® and dxa, it may be more clinically appropriate to assess bf% without prostheses when using either of these instruments. the bod pod® itself may be subject to measurement error related to isothermal air used to determine raw body volume (bvr). an incorrect raw body volume might underestimate body volume (bv) which in turn may overestimate body density (bd) leading to an underestimated and imprecise bf%. isothermal air trapped in clothing produces error,50 and may underestimate bf% in normal and overweight persons when loose fit clothing is compared with swimsuits or no clothing.51 as such, the present study suggests removal of the prosthesis during body composition assessment. although we did not investigate the ability of the bod pod® to track body composition changes, this is a popular method of in weight loss research. the bod pod® has been validated with dxa in several weight loss intervention studies with mixed results. in one study overweight participants were randomized to either a self-help group or weight loss program.52 at both pre and post measurements, bf% were lower in dxa than bod pod®.52 however, two other studies found bod pod® to underestimate bf% and overestimate fat free mass (ffm) compared to dxa.53,54 this trend was evident in the current study, where bf% from the bod pod® was lower than from the dxa while wearing prostheses. the results from this study suggest, that the bod pod® is a suitable option over the more resource demanding dxa. dual-energy x-ray absorptiometry might have an inability to discern changes in components of fat free mass components as this method assumes adequate hydration of ffm.55 however, we selected dxa as our criterion as opposed to hydrostatic weight as dxa considers bone density and is more precise in measurement than the relationship of percent body fat from bod pod and dxa with prosthesis relationship of percent body fat from bod pod and dxa without prosthesis https://doi.org/10.33137/cpoj.v6i1.41605 5 smith jd, guerra g, symons tb, kwon eh, yoon ej. comparison of body composition methods for estimating body fat percentage in lower limb prosthesis users. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.2. https://doi.org/10.33137/cpoj.v6i1.41605 canadian prosthetics & orthotics journal issn: 2561-987x body composition methods for estimating body fat percentage smith et al., 2023 bod pod®.56 as such, we believe differences seen between bod pod® and dxa are because of limitations of the bod pod® and not necessarily our sample of participants. furthermore, while some participants had to be assisted on the body weight scale without prostheses prior to bod pod® measurements, entering the chamber itself was safe and not cumbersome. some participants preferred to transfer themselves from a wheelchair to the chamber while others preferred to seat themselves in the chamber while wearing the prosthesis and then remove it just prior to measurement. limitations our study is not without limitations. our study was limited by a smaller sample with limited number of persons with transfemoral and bilateral amputations. subject selection may have influenced the results because of the unique anthropometry of participants with amputations. moreover, our group of participants had a bmi of 28.1 corresponding to an overweight classification (25.0 to 29.9 kg/m2). this may limit generalizability of our findings for those with lower limb amputations in other bmi ranges. still, others have reported bmi of 31.7 in people with dysvascular amputation,17 and a study of 16,259 individuals with nontraumatic amputation found 30.4% to be non-obese, 18.2% obesity class 1 (bmi= 30-34.9), 17.3% obesity class 2 (bmi= 35-39.9), and finally 34.1% with obesity class 3 (bmi≥40).57 although the bod pod® is a valid and reliable technique when estimating total bf% compared to the dxa, there are distinct advantages and disadvantages of either system. they are both simple to administer by practitioners and easy to perform by patients. the bod pod® is a less costly technique with no exposure to the very low radiation produced by the dxa. however, the dxa provides total values of fm, ffm and bone bass which differs from the bod pod® which measures the relative concentrations in estimating tissue content. regardless, the bod pod® is widely acceptable for body composition testing for a range of patient populations. our study suggests that it is also acceptable for measurement of body composition in lower limb prosthesis users. conclusion the rise of obesity around the world has ushered in a need for interventions as well as way of measuring body composition. assessing body weight and bmi changes alone is misleading and cannot measure changes in lean mass or fat mass. this study is a first to assess differences of the bod pod® to dxa in lower limb prosthesis users. the results of this study indicate that when considering measuring bf% with bod pod® using dxa as a criterion, bod pod® reports less difference and greater agreement of bf% when doffing the prostheses. future work will utilize the bod pod® in intervention studies for monitoring body composition changes across the continuum of rehabilitation. acknowledgements the authors would like to thank the participants and texas a&m university-san antonio. declaration of conflicting interests the authors declare no financial and personal relationships with organizations or individuals that might have influenced their research. authors contribution • john d. smith: original drafting, writing, data collection, statistical analysis. • gary guerra: conceptualization, writing, data collection, statistical analysis. • t.brock symons: writing, data collection, proofing. • eun hye kwon: writing, data collection, proofing. • eun jung yoon: writing, data collection, proofing. sources of support this research was supported by the coehd faculty grant program. ethical approval this study was approved by the texas a&m university san antonio institutional review board (log#2020-69) and all participants signed an informed consent form before study commencement. references 1.hales cm, carroll md, fryar cd, ogden cl. prevalence of obesity and severe obesity among adults: united states, 20172018. nchs data brief. 2020; 360:1-8. pmid: 32487284 2.ito h, nakasuga k, ohshima a, sakai y, maruyama t, kaji y, et al. excess accumulation of body fat is related to dyslipidemia in normal-weight subjects. int j obes relat metab disord. 2004;28(2):242-7. doi: 10.1038/sj.ijo.0802528 3.kim jy, han sh, yang bm. implication of high-body-fat percentage on cardiometabolic risk in middle-aged, healthy, normal-weight adults. obesity (silver spring). 2013;21(8):1571-7. doi: 10.1002/oby.20020. pmid: 23404833 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doi: 10.1097/00005768-19990900000019 41.wechsler, s. statistics at square one. 9th ed, revised by m. j. campbell, t. d. v. swinscow, bmj publ. group, london, isbn 07279-0916-9. statistics in medicine.1996; 16(22): 2629-2630 42.vincent w. statistics in kinesiology 3rd ed. champaign: human kinetics; 2004. 43.cohen, j. statistical power analysis for the behavioral sciences2nd ed. routledge.1988; doi:10.4324/ 9780203771587 44.fields da, goran mi, mccrory ma. body-composition assessment via air-displacement plethysmography in adults and children: a review. am j clin nutr. 2002;75(3):453–67. doi: 10.1093/ajcn/75.3.453 45.miyatake n, nonaka k, fujii m. a new air displacement plethysmograph for the determination of japanese body composition. diabetes, obes metab. 1999;1(6):347–51. doi:10.1046/j.1463-1326.1999.00064.x 46.ritz p, sallé a, audran m, rohmer v. comparison of different methods to assess body composition of weight loss in obese and diabetic patients. diabetes res clin pract. 2007;77(3):405–11. doi: 10.1016/j.diabres.2007.01.007 47.goosey-tolfrey v, keil m, brooke-wavell k, de groot s. a comparison of methods for the estimation of body composition in highly trained wheelchair games players. int j sports med. 2016;37(10):799–806. doi:10.1055/s-0042-104061 48.gibson al, heyward vh, mermier cm, janot jm, wilmerding mv. comparison of dxa, siri’s 2c, and lohman’s db-mineral models for estimating the body fat of physically active adults. int j sport nutr exerc metab. 2004;14(6):657–72. doi: 10.1123/ijsnem.14.6.657 49.deurenberg p, leenen r, van der kooy k, hautvast jg. in obese subjects the body fat percentage calculated with siri’s formula is an overestimation. eur j clin nutr. 1989;43(8):569–75. 50.vescovi jd, zimmerman sl, miller wc, fernhall b. effects of clothing on accuracy and reliability of air displacement plethysmography. med sci sports exerc. 2002;34(2):282–5. doi: 10.1097/00005768-200202000-00016 51.hull hr, fields da. effect of short schemes on body composition measurements using air-displacement plethysmography. dyn med. 2005;4(1):8. doi:10.1186/1476-59184-8 52.frisard mi, greenway fl, delany jp. comparison of methods to assess body composition changes during a period of weight loss. obes res. 2005;13(5):845–54. doi:10.1038/oby.2005.97 53.weyers am, mazzetti sa, love dm, gómez anal, kraemer wj, volek js. comparison of methods for assessing body composition changes during weight loss. med sci sport exerc. 2002;34(3). doi: 10.1097/00005768-200203000-00017 54.minderico cs, silva am, teixeira pj, sardinha lb, hull hr, fields da. validity of air-displacement plethysmography in the assessment of body composition changes in a 16-month weight loss program. nutr metab (lond) 2006;3(1):32. doi:10.1186/17437075-3-32 55.pietrobelli a, wang z, formica c, heymsfield sb. dual-energy x-ray absorptiometry: fat estimation errors due to variation in soft tissue hydration. am j physiol. 1998;274(5):e808-16. doi: 10.1152/ajpendo.1998.274.5.e808 56.pietrobelli a, formica c, wang z, heymsfield sb. dual-energy x-ray absorptiometry body composition model: review of physical concepts. am j physiol metab. 1996;271(6):e941–51. doi: 10.1152/ajpendo.1996.271.6.e941 57.al yafi m, nasif a, glosser ld, ren g, ahemd a, nazzal m, et al. the relationship between lower extremity amputation and body mass index. vascular. 2022;170853812210878. doi:10.1177/ 17085381221087824 https://doi.org/10.33137/cpoj.v6i1.41605 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 case study/case series pellegrini r, denza g, brunelli s, zenardi d, imperio m, vannozzi g, traballesi m. the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series. canadian prosthetics & orthotics journal. 2021; volume 4, issue 1, no.9. https://doi.org/10.33137/cpoj.v4i1.36252 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.36252 1 pellegrini r, denza g, brunelli s, zenardi d, imperio m, vannozzi g, traballesi m. the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series. canadian prosthetics & orthotics journal. 2021; volume 4, issue 1, no.9. https://doi.org/10.33137/cpoj.v4i1.36252 case study/case series the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series pellegrini r1, denza g1, brunelli s2 *, zenardi d1, imperio m3, vannozzi g3, traballesi m2 1 itop spa, officine ortopediche, palestrina, rome, italy. 2 fondazione santa lucia, scientific institute for research, hospitalization and health care, rome, italy. 3 department of movement, human and health sciences, foro italico, university of rome, rome, italy. introduction current trends relating to the design of the prosthesis for persons with transfemoral (tf) amputation lead to sockets and suspension systems that allow for a hip range of motion that is as close as possible to the physiological one, and that do not interfere with muscle activity. a socket with these characteristics should improve walking of persons with tf amputation.1,2 the socket is the interface between the prosthesis and the appendicular skeleton via residual limb soft tissue. the socket shape aims to ensure a comfortable use of the prosthesis both in static and in dynamic phases without causing pain.3 despite the improvement in technology in recent years, about 20% of persons with tf amputation are reported not walking at all at home while about 50% do not use the prosthesis outside.4 the most common transfemoral sockets is the ischial containment socket (ics).5 one drawback is the limitation of hip motion, in particular the hip extension, because it encloses the ischial tuberosity and the ramus within the socket. this shape is also reported to cause discomfort when the user is sitting.6 the marlo anatomical socket (mas) is an evolution of the ics. mas users have shown a significant improvement of open access volume 4, issue 1, article no.9. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: the subischial socket interface design is a promising new shape of socket for persons with transfemoral amputation. typically, the proximal trim line is located distal to the ischial tuberosity, improving comfort in prosthetic users without interfering with gait parameters compared to ischial containment socket (ics). no studies have investigated the performances of a subischial sockets with suction suspension system. a new subischial socket (hybrid subischial socket hyss) combined with a hypobaric passive suspension system has been recently developed. objective: to assess the effects of hyss in terms of comfort, hip range-of-motion and gait parameters. methodology: three persons with transfemoral amputation were tested first using their usual ics and then after one month of continuous use of hyss. findings: the following parameters improved in all participants using hyss: 1) hip range-of-motion, 2) walking speed and distance, 3) timed-up-and-go-test time, 4) stride length, 5) double support duration, 6) peak value of hip extension during stance, 7) satisfaction with the prosthesis. conclusion: these findings suggest that the use of hyss could allow improvements for prosthetic use. article info received: march 25, 2021 accepted: july 1, 2021 published: july 14, 2021 citation pellegrini r, denza g, brunelli s, zenardi d, imperio m, vannozzi g, traballesi m. the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series. canadian prosthetics & orthotics journal. 2021; volume 4, issue 1, no.9. https://doi.org/10.33137/cpoj.v4i 1.36252 keywords artificial limb, prosthetic socket, gait analysis, transfemoral amputation, locomotion, ischial containment, socket comfort * corresponding author stefano brunelli, md fondazione santa lucia, scientific institute for research, hospitalization and health care, rome, italy. e-mail: s.brunelli@hsantalucia.it orcid id: https://orcid.org/0000-0002-5986-1564 https://doi.org/10.33137/cpoj.v4i1.36252 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.36252 https://doi.org/10.33137/cpoj.v4i1.36252 mailto:s.brunelli@hsantalucia.it https://orcid.org/0000-0002-5986-1564 2 pellegrini r, denza g, brunelli s, zenardi d, imperio m, vannozzi g, traballesi m. the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series. canadian prosthetics & orthotics journal. 2021; volume 4, issue 1, no.9. https://doi.org/10.33137/cpoj.v4i1.36252 issn: 2561-987x the hybrid subischial socket for persons with transfemoral amputation pellegrini et al. 2021 cpoj gait efficiency and prosthesis-related perceived mobility compared to ics. although the ischium and gluteus maximum are not included in the mas because of the lowered posterior shelf, even requires an interaction with the pelvis due to lateral containment.2 the subischial socket has been a recent development in socket design.7 in this socket the proximal trim line is located distal to the ischial tuberosity and it does not interact with the pelvis. in the last decade some studies had shown how the subischial socket could improve the spatiotemporal gait parameters, the functional performance with the prosthesis and the comfort compared to the ics.2,8-11 the vacuum assisted suspension system was used in all these studies. more recently the northwestern university, prosthetic orthotic center, chicago, illinois, usa has described the construction technique necessary to create a subischial socket with a suction suspension system: the nu-flex sis.12 this technical note showed that suspension systems can involve differences in socket shape compared to the subischial socket ensured by vacuum. a subischial socket (hybrid subischial socket hyss) has been developed, embedding a suspension system that is ensured by a hypobaric liner seal-in x® without an external sleeve and without vacuum. its internal shape has four areas of tissue compression obtained with a casting technique and without rectification procedures as previously described in the literature.7,12 the hyss includes an inner socket made of biomedical silicone and an external carbon fiber frame. figure 1 shows the differences between ics and hyss. figure 1: differences between ischial containment socket (left side grey socket) and hybrid subischial socket (right side blue socket). top left: frontal view. top right: posterior view. bottom left: medial view: bottom right: lateral view. the shape and the principles of manufacturing of hyss, as in the other subischial sockets, may represent a benefit for the ics prosthesis users. the pelvis is free from the contact with the socket, thus an increase in hip range of motion (rom) should be observed (figure 2).13 an increase in rom should “free” the hip during walking with better performances in terms of speed, endurance, motor ability and comfort during prosthesis use. figure 2: posterior view of hyss. in this case, the socket is coated with silicone for aesthetic purposes. to the best of our knowledge, no previous studies have investigated the functional effects of a subischial socket with suction suspension system. this report describes the differences in terms of gait parameters, hip rom and satisfaction with the prosthesis following the change of the socket (from ics to hyss) in three persons affected by tf amputation. methodology 2.1 participants we randomly selected the persons with tf amputation among those accessing the local prosthetics-orthotics center, informing them about the opportunity to try the new socket. the inclusion criteria included being over the age of 18, being able to provide informed consent, having a transfemoral amputation, and being a prosthesis user. informed consent was obtained from the participants after they were provided with an accurate description of the hyss and the purpose of the tests they would be subjected to. this case study was a pilot study; a forthcoming larger study is planned for which ethics committee approval is pending. 2.2 testing protocols gait kinematic was measured using a smart dx700 from bts bioengineering (milan, italy), which consisted of eight infrared cameras, used to record the position of 22 passive markers, applied on the subjects following the davis https://doi.org/10.33137/cpoj.v4i1.36252 3 pellegrini r, denza g, brunelli s, zenardi d, imperio m, vannozzi g, traballesi m. the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series. canadian prosthetics & orthotics journal. 2021; volume 4, issue 1, no.9. https://doi.org/10.33137/cpoj.v4i1.36252 issn: 2561-987x the hybrid subischial socket for persons with transfemoral amputation pellegrini et al. 2021 cpoj protocol,14 at a rate of 250 hz. kinematics data were then combined with the kinetic one obtained using four force plates (bts p-6000), each one containing four load cells that use strain gauges.15 a recording is also done with two optical cameras bts vixta (sampling rate: 25 hz) to combine each test with a real-time video recording. data analysis was performed using bts smart software, which is associated to the used devices; it calculates spatiotemporal parameters, joint kinematics and kinetics from the raw data acquired by the cameras and the force plates. the covered distance during six-minute walking test (6mwt) and duration of the timed-up-and-go-test (tug) were obtained using one inertial measurement unit (g-sensor, bts), firmly attached on the pelvis of the participant16 and the relevant gait parameters calculated.17,18 for analysis subset of them, the degree of asymmetry (doa) was calculated as in previous studies,9,19 because it allows for the assessment of the differences between the contralateral and prosthetic leg during locomotion tasks. in a healthy individual, the asymmetry is lower compared to a person with unilateral lower limb amputation, thus an effective prosthesis should lead to doa for all measured values as low as possible. the doa represents the variation between the sound leg (s) and the prosthetic leg (p) which is obtained using the following formula: 𝐷𝑜𝐴 = ( 𝑆−𝑃 𝑆+𝑃 ) ∗ 100 2.2.1 hip range of motion maximum values of hip extension, flexion and abduction on the prosthetic side were measured using a long arm goniometer and the protocol proposed by norkin.20 four measurements were performed for each variable and, then, the relevant mean values were calculated (figure 3). figure 3: measurement of hip flexion of the prosthetic side. 2.2.2 gait analysis subjects were asked to walk on a straight line at a selfselected speed inside the measurement area defined by the cameras. five trials were recorded, during which at least one gait cycle could be identified using the force plate data. focusing on a full gait cycle for each leg, based on both kinematics and kinetics measurements and the identification of the heel strike and toe-off events, the mean value of the following parameters was calculated:21,22 1) walking speed (m/s), 2) cadence (steps/min), 3) step width (m), 4) stride length (m), 5) double support (%), 6) hip extension (degrees).23 for a subset of the above mentioned gait analysis parameters, the doa was also calculated:9 1) step length (doa), 2) stance duration (doa), 3) swing duration (doa), 4) single support duration (doa). hip angles on the sagittal plane of both legs were exported in matlab. an algorithm was implemented to identify the peak value of the extension of the prosthetic hip and sound leg during the stance phase, as in a study by tranberg et al.13 2.2.3 performance tests using a wearable sensor with an inertial sensor placed on the l5 vertebra, each subject walked on a straight line back and forth for six minutes.24 the path was 10 meters long inside the laboratory. the proprietary software (g-studio) provided the total distance traveled (6mwt). with the same set-up, the participants were asked to stand up from a chair, to walk for three meters and, then, to turn back and sit down again, recording the amount of time necessary for the patient to perform the task (tug).25 2.2.4 self-evaluation test to determine comfort and improvement of quality of life provided by the use of the prosthesis, the participants completed the satpro questionnaire which involves 15 items related to the use of the prosthesis in daily life measured using a four-level scale (score 0-45, where 45 means maximum satisfaction).26 2.3 timing and socket change all the mentioned evaluation tools were administered twice. the first measurement occurred after the first evaluation https://doi.org/10.33137/cpoj.v4i1.36252 4 pellegrini r, denza g, brunelli s, zenardi d, imperio m, vannozzi g, traballesi m. the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series. canadian prosthetics & orthotics journal. 2021; volume 4, issue 1, no.9. https://doi.org/10.33137/cpoj.v4i1.36252 issn: 2561-987x the hybrid subischial socket for persons with transfemoral amputation pellegrini et al. 2021 cpoj session performed with the ics socket. participants were also fit with the hyss at this first appointment. after one month of acclimation to the new socket, participants performed the second evaluation session while wearing the hyss socket. only the sockets were changed between sessions. socket alignment was performed by a team of certified experienced prosthetists. results in this preliminary study, 3 males with tf amputation were enrolled. all of them were k-level 4 prosthetic users, fitted with an ics socket and a seal-in suspension system. proper fit and function of the existing prosthesis were confirmed by a certified prosthetist. the demographic and prosthetic information is reported in table 1. as shown in table 2, no difference was found in terms of variation of cadence, step width and all doas in each participant while wearing the ics or hyss socket. an improvement was observed in the following parameters in all participants donning hyss: 1) passive hip rom, 2) the distance covered during 6mwt, 3) the time of tug and the following kinematic and temporal parameters related to gait, 4) stride length, 5) double support duration, 6) walking speed and 7) peak value of hip extension during stance phase for both legs (table 2). table 1: demographic and prosthetic information of the sample. bmi= body mass index. patient age (yrs.) bmi (kg/m2) side klevel cause of amputation time since amputation suspension system knee foot 1 18 19.58 right 4 cancer 10 months seal-in genium pro-flex 2 35 21.26 left 4 trauma 18 years seal-in genium vari-flex 3 32 26.69 left 4 trauma 7 months seal-in genium pro-flex table 2: results obtained for each participant with both sockets. the difference (dif%) is expressed as percentage variation. ics: ischial containment socket. hyss: hybrid subischial socket. doa: degree of asymmetry. measure patient 1 patient 2 patient 3 ics hyss dif% ics hyss dif% ics hyss dif% hip range of motion abduction° 30 ± 6 45 ± 6 +50 18 ± 6 32 ± 5 +77.78 34 ± 4 40 ± 4 +17.65 flexion° 88 ± 11 96 ± 11 +9.09 65 ± 10 95 ± 13 +46.15 77 ± 12 110 ± 12 +42.86 extension° 21 ± 7 25 ± 6 +19.05 10 ± 7 21 ± 9 +110 10 ± 8 20 ± 8 +100 gait analysis (global temporal parameters) walking speed (m/s) 1.1 ± 0.0 1.2 ± 0.0 +9.09 0.9 ± 0.1 1.1 ± 0 +22.22 1.1 ± 0 1.2 ± 0 +9.09 cadence (steps/min) 101.8 ± 1.7 104.8 ± 2.6 +2.95 97 ± 3 100.2 ± 1.1 +3.3 108.7 ± 0.8 109.9 ± 2.6 +1.1 gait analysis (global spatial parameters) step width (m) 0.10 ± 0.01 0.11 ± 0.01 +10 0.12 ± 0.01 0.10 ± 0.01 -16.67 0.17 ± 0.01 0.16 ± 0.03 -5.88 gait analysis (p-leg temporal and spatial parameters) stride length (m) 1.29 ± 0.04 1.42 ± 0.6 +10.0 1.11 ± 0.03 1.29 ± 0.03 +16.2 1.21 ± 0.01 1.31 ± 0.03 +8.2 double support duration (%) 15.1 ± 0.8 13.2 ± 0.9 -12.5 17.9 ± 1.3 11.4 ± 0.8 -36.3 19.5 ± 0.4 14.2 ± 1.1 -27.1 gait analysis (peak angles during stance phase) p-leg hip extension° -19.9 ± 0.8 -19.7 ± 1.7 -1.0 -3.5 ± 0.9 -8.2 ± 0.6 -134.2 3.4 ± 1.1 1.2 ± 0.9 -64.7 s-leg hip extension° -14.2 ± 1.7 -14.7 ± 2.2 -3.4 -6.3 ± 1.2 -8.1 ± 0.9 -28.5 1.5 ± 1.9 -4 ± 3 -366.6 gait analysis (asymmetry between legs) step length (doa) 4 ± 3 -3.9 ± 1.9 -8.18 -1 ± 6 0.1 ± 0.8 1.14 -0.7 ± 0.5 0.9 ± 1.2 1,66 stance duration (doa) 6.2 ± 1.7 6.3 ± 1.4 0.09 5.3 ± 2.2 3.2 ± 1.9 -2.20 1.7 ± 0.9 4.5 ± 2.8 2,85 swing duration (doa) -10.9 ± 2.8 -10.8 ± 2.9 0,16 -10 ± 5 -5 ± 3 5.31 -3.9 ± 1.8 -8 ± 5 -4.75 single support duration (doa) 8 ± 6 11 ± 3 2,35 9 ± 6 5 ± 6 -3.99 1.0 ± 2.5 8 ± 7 7.20 timed-up and go duration (s) 15.2 ± 0.5 13.1 ± 1.5 -13.82 15.3 ± 0.7 13.6 ± 0.8 -11.11 10.7 ± 0.7 9.1 ± 0.3 -14.95 6-minute walking test distance (m) 300 340 +13.33 na 320 270 380 +40.74 sat-pro score 43 45 +4.6 35 43 +22.8 28 34 +21.4 https://doi.org/10.33137/cpoj.v4i1.36252 5 pellegrini r, denza g, brunelli s, zenardi d, imperio m, vannozzi g, traballesi m. the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series. canadian prosthetics & orthotics journal. 2021; volume 4, issue 1, no.9. https://doi.org/10.33137/cpoj.v4i1.36252 issn: 2561-987x the hybrid subischial socket for persons with transfemoral amputation pellegrini et al. 2021 cpoj based on self-evaluation tests that are known to be indicative of the participants’ opinion of the sockets, all participants reported greater satisfaction with hyss (table 2) discussion all three participants in this case series demonstrated improvement in hip rom, some gait parameters, and satisfaction with the prosthesis when using the hyss compared to the ics. the increase in passive hip rom confirms the sub-ischial design overcomes one disadvantage of the ischial containment socket, which is characterized by an increased constraint on the hip of the affected limb, as shown by other authors.2,8,26 our results clearly indicate increased rom in both ab/adduction and flexion-extension of the hip, obtaining higher maximum angles, with percentage change that reaches +110% in hip extension for one patient. greater degree of hip flexion is also achieved during walking and for both the prosthetic and the sound limbs, with values obtained for all patients that are closer to those observed in normal gait. the satpro results suggest an increased overall comfort using the hyss, probably due to the greater rom. two patients reported a remarkable improvement in satpro answers (+22% and +21%), while the third one had a lower improvement (+4%) probably due to his higher ics score. parameters obtained during clinical performance tests indicate an improved involvement of the prosthetic leg while performing common daily tasks, which were performed at increased speed. for both 6mwt and tug, a positive variation was observed, above the minimum detectable change in amputated individuals (mdc) of 45.0 m and 1.28s, respectively, as reported in literature.27,28 certain biomechanical characteristics, like cadence, step width and all gait phase durations express as doa are characterized by values that do not vary consistently or with a remarkable increment or decrement. thus, the effect of the socket on these aspects of the gait can be considered minimal. while presenting these main advantages over ics sockets, this new hybrid sub-ischial design does not present any remarkably negative variation on typical gait parameters. asymmetry between legs does not vary significantly and consistently, with non-negligible percentage variation typically associated with a higher standard deviation that does not allow to interpret the results obtained with different sockets as different. improvements on gait velocity and stride length (around +10% or more for both measures and for each patient) with a negligible cadence variation (between +1% and +3%) could indicate a safer gait, with an improvement in walking speed mainly caused by longer footsteps. another interesting result is the change in the duration of double support phase within the gait cycle of the affected limb expressed as percentage of the whole cycle. in fact, it is shown how double support phase occupies a smaller amount of the gait cycle because of the increase in velocity.29 this can be considered as another sign of improvement in subjects’ walking, since increased values of double support duration in healthy subjects is typically found in the elderly.30 these results are in line with the those obtained with the nu-flexsiv socket, where gait analysis parameters are unaffected by a lower brim, while hip roms are improved as expected by a design that does not contain the ischial ramus inside the prosthesis.2 new sub-ischial sockets represent a new possibility to improve the quality of life of the individuals affected by lower limb amputations. the material used for hyss, biomedical silicone, allows to precisely customize the morphology, thickness, stiffness and color to produce socket that combine desirable features.31 the results obtained from this case series should be considered preliminary due to the low number of participants involved. future work will consist of a larger cohort of individuals with limb loss. conclusion the hyss can be considered an improvement over ischial containment sockets, because of the potential to overcome some common problems with ics designs while achieving similar performance in other aspects of use. acknowledgements thanks to itop spa, officine ortopediche, palestrina, rome, italy for the design and fabrication of custom hyss. declaration of conflicting interests all the authors declare to have no conflicts of interest to declare. author contribution • roberto pellegrini: design and fabrication of hyss, supported the writing of the manuscript. • gabriele denza: acquisition, analysis of the data, led the writing of the manuscript. • stefano brunelli: conceived idea of the work, led the writing of the manuscript. • daniele zenardi: design and fabrication of hyss, supported the writing of the manuscript. https://doi.org/10.33137/cpoj.v4i1.36252 6 pellegrini r, denza g, brunelli s, zenardi d, imperio m, vannozzi g, traballesi m. the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series. canadian prosthetics & orthotics journal. 2021; volume 4, issue 1, no.9. https://doi.org/10.33137/cpoj.v4i1.36252 issn: 2561-987x the hybrid subischial socket for persons with transfemoral amputation pellegrini et al. 2021 cpoj • matteo imperio: acquisition, managed the data files, drafted the manuscript. • giuseppe vannozzi: revised the manuscript critically for important intellectual content, supported the data analysis, interpretation of the data. • marco traballesi: revised the manuscript critically for important intellectual content. sources of support the authors received no financial support for the research, authorship or publication of this article. ethical approval this case study was a pilot study; a forthcoming larger study is planned for which ethics committee approval is pending. references 1.traballesi m, delussu as, averna t, pellegrini r, paradisi f, brunelli s. energy cost of walking in transfemoral amputees: comparison between marlo anatomical socket and ischial containment socket. gait posture. 2011;34(2):270-4. doi:10.1016/j.gaitpost.2011.05.012 2.fatone s, caldwell r. northwestern university flexible subischial vacuum socket for persons with transfemoral amputation: part 2: description and preliminary evaluation. prosthet orthot int. 2017;41:246–50. doi:10.1177/0309364616685230 3.safari r. lower limb prosthetic interfaces: clinical and technological advancement and potential future direction. prosthet orthot int. 2020;44(6):384-401. doi:10.1177/0309364620969226 4.kamrad i, söderberg b, hedvig örneholm h, hagberg k. swedeamp the swedish amputation and prosthetics registry: 8year data on 5762 patients with lower limb amputation show sex differences in amputation level and in patient-reported outcome. acta orthopaedica. 2020;91(4):464-70. doi:10.1080/17453674. 2020.1756101 5.schuch cm, pritham ch. current transfemoral sockets. clin orthop relat res. 1999;361:48–54. 6.hagberg k, häggström e, uden m, bränemark r. socket versus bone-anchored trans-femoral prostheses: hip range of motion and sitting comfort. prosthet orthot int. 2005;29(2):153-63. doi:10.1080/03093640500238014 7.fatone, s., caldwell, r.. northwestern university flexible subischial vacuum socket for persons with transfemoral amputation-part 1: description of technique. prosthet orthot int. 2017;41(3):237-45. doi:10.1177/0309364616685229 8.kahle jt, highsmith mj: transfemoral sockets with vacuumassisted suspension comparison of hip kinematics, socket position, contact pressure, and preference: ischial containment versus brimless. j rehabil res dev 2013;50(9):1241-1252. doi:10.1682 /jrrd.2013.01.0003 9.kahle jt, highsmith mj. transfemoral interfaces with vacuum assisted suspension comparison of gait, balance, and subjective analysis: ischial containment versus brimless. gait & posture. 2014;40(2):315-20. doi:10.1016/j.gaitpost.2014.04.206 10.brown se, esposito e, ikeda a, fergason j, caldwell r, fatone s. effect of socket design and suspension on walking mechanics. in proceedings of the 40th annual meeting of the american society of biomechanics, raleigh, nc 2016 aug (pp. 2-5). http://www.asbweb.org/conferences/2016/abstracts/allabstracts_2 016.pdf 11.strachan e, davis a, wontorcik l. stride-to-stride temporalspatial gait variability and vacuum pressure deviation of transfemoral amputees ambulating with sub-ischial prostheses. in american academy of orthotists & prosthetists 37th academy annual meeting and scientific symposium 2011 mar 16. 12.caldwell r, fatone s. technique modifications for a suction suspension version of the northwestern university flexible subischial vacuum socket: the northwestern university flexible subischial suction socket. prosthet orthot int. 2019;43(2):233-9. doi:10.1177/0309364618798869 13.tranberg r, zugner r, karrholm j. improvements in hipand pelvic motion for patients with osseointegrated trans-femoral prostheses. gait posture. 2011;33:165–8. doi:10.1016/j.gaitpost. 2010.11.004 14.davis rb, õunpuu s, tyburski d, gage jr. a gait analysis data collection and reduction technique. human movement science. 1991;10(5):575–87. doi:10.1016/0167-9457(91)90046-z 15.paradisi f, di stanislao e, summa a, brunelli s, traballesi m & vannozzi g. upper body accelerations during level walking in transtibial amputees. prosthet orthot int. 2019;43(2):204-12. doi:10.1177/0309364618792745 16.beausoleil s, miramand l, turcot k. evolution of gait parameters in individuals with a lower-limb amputation during a sixminute walk test. gait posture. 2019;72:40-5. doi:10.1016/ j.gaitpost.2019.05.022 17.salarian a, horak fb, zampieri c, carlson-kuhta p, nutt jg, aminian k. itug, a sensitive and reliable measure of mobility. ieee trans neural syst rehabil eng. 2010;18(3):303-10. doi:10.1109/ tnsre.2010.2047606 18.highsmith mj, kahle jt, carey sl, lura dj, dubey rv, csavina kr, et al. kinetic asymmetry in transfemoral amputees while performing sit to stand and stand to sit movements. gait posture. 2011;34(1):86-91. doi:10.1016/j.gaitpost.2011.03.018 19.norkin cc, white dj. measurement of joint motion: a guide to goniometry. fa davis; 2016. 20.varrecchia t, serrao m, rinaldi m, ranavolo a, conforto s, de marchis c, et al. common and specific gait patterns in people with varying anatomical levels of lower limb amputation and different prosthetic components. hum mov sci. 2019;66:9-21. doi:10.1016/ j.humov.2019.03.008 21.waters rl, perry j, antonelli d, hislop h. energy cost of walking of amputees: the influence of level of amputation. j bone joint surg am. 1976;58(1):42-6. 22.kark l, vickers d, mcintosh a, simmons a. use of gait summary measures with lower limb amputees. gait posture. 2012;35(2):23843. doi:10.1016/j.gaitpost.2011.09.013 https://doi.org/10.33137/cpoj.v4i1.36252 http://www.asbweb.org/conferences/2016/abstracts/allabstracts_2016.pdf http://www.asbweb.org/conferences/2016/abstracts/allabstracts_2016.pdf 7 pellegrini r, denza g, brunelli s, zenardi d, imperio m, vannozzi g, traballesi m. the hybrid subischial socket for persons with transfemoral amputation: gait parameters and clinical assessment of a case series. canadian prosthetics & orthotics journal. 2021; volume 4, issue 1, no.9. https://doi.org/10.33137/cpoj.v4i1.36252 issn: 2561-987x the hybrid subischial socket for persons with transfemoral amputation pellegrini et al. 2021 cpoj 23.bilodeau s, hébert r, desrosiers j. questionnaire sur la satisfaction des personnes amputées du membre inférieur face à leur prothèse: développement et validation. occup ther. 1998;66:23-31. doi:10.1177/000841749906600103 24.storm fa, cesareo a, reni g, biffi e. wearable inertial sensors to assess gait during the 6-minute walk test: a systematic review. sensors (basel). 2020;20(9):2660. doi:10.3390/ s20092660 25.weiss a, herman t, plotnik m, brozgol m, giladi n, hausdorff jm. an instrumented timed up and go: the added value of an accelerometer for identifying fall risk in idiopathic fallers. physiol meas. 2011;32(12):2003. doi:10.1088/0967-3334/32/12/009 26.rabuffetti m, recalcati m, ferrarin m. trans-femoral amputee gait: socket pelvis constraints and compensation strategies. prosthet orthot int. 2005;29:183–92. doi:10.1080/ 03093640500217182 27.resnik l, borgia m. reliability of outcome measures for people with lower-limb amputations: distinguishing true change from statistical error. phys ther. 2011;91(4):555-65. doi:10.2522/ptj. 20100287 28.clemens sm, gailey rs, bennett cl, pasquina pf, kirksanchez nj, gaunaurd ia. the component timed-up-and-go test: the utility and psychometric properties of using a mobile application to determine prosthetic mobility in people with lower limb amputations. clin rehabil. 2018;32(3):388-97. doi:10.1177/ 0269215517728324 29.hebenstreit f, leibold a, krinner s, welsch g, lochmann m, eskofier bm. effect of walking speed on gait sub phase durations. hum mov sci. 2015;43:118-24. doi:10.1016/j.humov.2015.07.009 30.ferrandez am, pailhous j, durup m. slowness in elderly gait. exp aging res. 1990;16(2):79-89. doi:10.1080/ 07340669008251531 31.uellendahl je, mandacina s, ramdia s. custom silicone sockets for myoelectric prostheses. j prosthet orthot. 2006;18: 35–40. doi:10.1097/00008526-200604000-00003 https://doi.org/10.33137/cpoj.v4i1.36252 volume 6, issue 2 2023 articles in this special issue has been invited and reviewed by dr. silvia ursula raschke and dr. hossein gholizadeh. d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e v o l u t i o n i n p r o s t h e t i c s & o r t h o t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x https://jps.library.utoronto.ca/index.php/cpoj/editorinchief 1 gutierrez a.r. exploring the future of prosthetics and orthotics: harnessing the potential of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.7. https://doi.org/10.33137/cpoj.v6i2.42140 stakeholder perspectives exploring the future of prosthetics and orthotics: harnessing the potential of 3d printing gutierrez a.r* bionic prosthetics and orthotics group llc, merrillville, indiana, usa. introduction in the last decade, prosthetics and orthotics (p&o) have embraced technological progress, particularly in bionic advancements, boosting patient mobility outcomes. recently, focus has turned to enhancing the p&o interface, crucial for effective clinical interventions. over the past 6+ years, 3d printing has transformed accessibility, workflow, and implementation, impacting prosthetic and orthotic procedures. 3d printing in general, is a robust tool for fabricating complicated objects in a cost-effective and timely manner.1 despite initial challenges, collaborative efforts between technical printer manufacturers, software developers, and clinicians have streamlined digital workflows, promoting increased adoption of this technology in clinical practices. our clinical group, bionic prosthetics and orthotics group (www.bionicpo.com), has been at the forefront of implementation of 3d printing into our clinical practice, primarily in prosthetic cases, utilizing fdm (fused deposition modeling). we were attempting to standardize and improve the timeliness of our clinical workflow and overcome the traditional time-consuming fabrication methods of hand casting, plaster model modifications, thermoforming and lamination to enable our clinicians to spend more time focusing on patient care. rapid production in 3d printed sockets may shorten the time from evaluation to delivery of the prosthesis,2 socket modifications after limb shape changes; which could improve clinical outcomes in prosthesis use3 and limit any negative effects of socket disuse.4 for this transformation to occur, we had to demonstrate outcomes of printed devices could match those attained with standard fabrication devices. the key challenges to penetrating this space in our practice were digital scanning technology, printing materials and strength, printing time, and digital workflow efficiency. digital shape capture during this period, the p&o field had access to cad/cam technology with white light scanners, offering heightened accuracy. yet, the integration across multiple clinic locations was challenging due to financial, hardware, and reliability limitations. despite having a few white light scanners within our practice, the consistency and efficiency were burdensome, often exceeding the time of traditional methods; additionally, lacking an in-house carver, we resorted to costlier central fabrication for diagnostic sockets. open access abstract this paper explores the transformative impact of 3d printing on orthotics and prosthetics, focusing on enhancing patient outcomes and clinical efficiency. over the past decade, the integration of additive manufacturing has revolutionized device fabrication, particularly in diagnostic socket production, leading to significant time reductions in patient care. this article addresses challenges such as material limitations and the need for equivalent strength to traditional sockets, exploring the use of petg filaments and advanced printers. it emphasizes the role of digital scanning and model modification technology, highlighting affordable solutions like structure sensor scanners and iphone-based capture systems in shaping the digital workflow. the importance of a standardized digital workflow in clinical settings is discussed, showcasing reduced practitioner time and improved patient care. the paper concludes by outlining ongoing efforts to enhance patient care through automation and flexible prints. in summary, this paper provides a concise overview of the impactful advancements in orthotics and prosthetics through 3d printing, highlighting its potential for improved clinical efficiency and patient outcomes. citation gutierrez a.r. exploring the future of prosthetics and orthotics: harnessing the potential of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.7. https://doi.org/10.33137/cpoj.v6i2.42140 keywords orthotics, prosthetics, 3d printing, additive manufacturing, digital workflow, diagnostic sockets, material strength, clinical efficiency, prosthetic interface * corresponding author: anthony r gutierrez, cp/lp bionic prosthetics and orthotics group llc, merrillville, indiana, usa. e-mail: tony@bionicpo.com orcid id: https://orcid.org/0009-0002-2215-1750 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.7, 2023 special issue https://doi.org/10.33137/cpoj.v6i2.42140 http://www.bionicpo.com/ https://doi.org/10.33137/cpoj.v6i2.42140 https://orcid.org/0009-0002-2215-1750 https://jps.library.utoronto.ca/index.php/cpoj/index 2 gutierrez a.r. exploring the future of prosthetics and orthotics: harnessing the potential of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.7. https://doi.org/10.33137/cpoj.v6i2.42140 canadian prosthetics & orthotics journal issn: 2561-987x harnessing the potential of 3d printing in p&o gutierrez a.r, 2023 (special issue) a pivotal shift occurred when structure sensor scanners, coupled with an apple ipad, entered the scene, providing affordable scanning. this enabled our practitioners to do quick limb scanning with a familiar technology, a crucial efficiency lesson for our journey towards standardized 3d printing integration. the importance of consistent shape capture across a large team is vital to the program's success. our group has traditionally used the structure sensor and ipad interface, but recently the availability of new structure sensors has been limited and has created a challenge as our technology is aging and accuracy issues were realized. we have recently transitioned to orten capture software (orten 3d cam 6.0.1 (588)) (https://orten.proteor.com/orten), utilizing the iphone front camera system. all clinicians on our team utilize the same phone for clinical purposes, and this was an ideal solution to create uniformity across all scans coming into the fabrication team, which has led to more consistent output. material limitations at the time that we started this work, pla (polylactic acid) and abs (acrylonitrile butadiene styrene) were plastic filaments that were widely available and utilized by hobby printers and were the first materials utilized in the p&o space. while these filaments are easy to print with, the material was not familiar to the p&o clinician to utilize in a clinical sense. in the prosthetic clinical workflow, a vital part of the process is the diagnostic socket fitting. these sockets are utilized as a platform to create the definitive fabrication of the prosthesis. clinicians are often modifying the socket shape via heat and removal of material to create the customized socket that will be implemented as a long-term solution for the patient. the problem with printed sockets was that pla and abs do not behave like traditional thermoplastic materials used by the field in the modification process necessary during diagnostic fittings, thus our clinicians struggled with implementing 3d printed solutions into their practice. in time, we were able to find more suitable petg filaments that could be utilized and manipulated with similar methods to traditional fabrication. however, our initial printers were standard flow fdm printers (with a nozzle dimension of .6mm utilizing 1.25 mm filament), and in order to print a diagnostic socket which was strong enough withstand socket donning and static weight bearing, we needed to print a socket with sufficient material thickness to ensure strength during weight-bearing and dynamic alignment of the prosthesis. to accomplish this, we had to print with an inner shell, an internal honeycomb structure, and an outer shell to complete the socket shape. while this was able to create a socket that was strong enough for fittings, it was opaque, and thus not an equivalent process to traditional fabrication as modification of the material was still a challenge due to the dual wall design with 25-50% infill based on patient activity characteristics. printing time in our traditional workflow, a limb impression is taken, filled with plaster, hand modified, thermoformed, and trimmed. this process would involve about 1 hour of practitioner time and 1.5 hours of technician time. in our initial digital workflow, with a standard flow printer, we could capture the limb impression and digitally modify it in about 15 minutes, then the socket could be designed for printing in about 10 minutes. however, depending on the size of the residual limb, it takes about 8-12 hours to 3d print a petg or nylon socket with 25-50% infill percentage using a filament innovations icarus gen 1.0 printer. while practitioner time was greatly reduced, we were still behind on the technical timeline and still had not created a more efficient process, as we had one standard flow printer servicing nine clinics. the first breakthrough of printed sockets in mass adaptation into our workflow was when we partnered with filament innovations and their high-flow kratos, which was able to utilize a 2.5 mm nozzle and 2.85 mm filament. the output of this machine gave us the closest replica of a standard fabrication diagnostic socket. the printer was able to produce a diagnostic socket of a petg material that was a solid piece with a 4 mm wall thickness (no infill) in 1.5 hours and 15 minutes technical post processing of the socket for patient use. this material was able to be modified during the fitting appointment with the same processes as traditionally fabricated materials and was able to be used in both static and dynamic fittings. reaching this benchmark enabled our practice to fully adopt a digital workflow. we were able to drop our practitioner’s time from 1 hour to 15 minutes and our technician’s hands-on time from 1.5 hours to 15 minutes. this was an incredible efficiency booster on both our clinical and technical sides and led to mass adoption in our practice. strength testing in 3d printing one of the biggest questions we had in the initial implementation of 3d printing prosthetic sockets with highflow printers was: are they equivalent in strength compared to a traditionally fabricated socket? anecdotally within our clinics, we saw that the strength of the petg sockets we were producing were similar to that of traditional diagnostic sockets. to explore this further, we partnered with rosalind franklin university in north chicago, illinois by collaborating on a department of defense funded grant, under the orthotics and prosthetics outcomes research program. we conducted a systematic review to better understand the current state of this newer fabrication method, with a focus on the structural integrity of 3d printed sockets and factors that can affect the strength of 3d printed sockets when tested using iso 10328 standards. based on our search, we determined that direct comparison between studies was https://doi.org/10.33137/cpoj.v6i2.42140 https://orten.proteor.com/orten https://www.filamentinnovations.com/ https://www.filamentinnovations.com/ 3 gutierrez a.r. exploring the future of prosthetics and orthotics: harnessing the potential of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.7. https://doi.org/10.33137/cpoj.v6i2.42140 canadian prosthetics & orthotics journal issn: 2561-987x harnessing the potential of 3d printing in p&o gutierrez a.r, 2023 (special issue) challenging based on methodological differences including limited sample size, different testing conditions, infill percentages, and reinforcements near the socket pylon interface. regardless, our systematic review results did show that 3d printed sockets were trending towards producing similar failure forces as those observed in laminated sockets.5 we complemented this review with empirical data collected by our group in which we performed ultimate failure testing of 3d printed composite sockets using some of the latest filaments available.for 3d printed sockets, three different material filaments were used: petg (filament innovations, pennsylvania, usa); polycarbonate or pc (polymax-pc, polymaker, changshu, china); and copolymer polypropylene or cpx (filament innovations, pennsylvania, usa). cpx is a specific co-polymer polypropylene filament that, as per manufacturer information, has higher strength characteristics than standard co-polymer propylene. we refer to the filament using the manufacturers name, cpx, rather than the generic co-polymer propylene to highlight this difference) and compared the results to that of a standard laminated composite (nano resin, paceline advanced medical solution) and a lay-up consisting of braided carbon fiber (st&g usa corp.), nyglass stockinette (paceline advanced medical solution), and nysert (sps). in this case, the layup consisted of a layer each of (in this order) carbon braid, nyglass, nysert, nyglass, carbon braid and feather stretch nylon stocking. another polyvinyl alcohol bag was placed over the layup. the thermosetting resin, activated with the promoter or hardener, was then poured into the bag and was subjected to vacuum to evenly spread the resin throughout the layup on the mold. manual stringing of the resin was performed from the outside of the pva bag to ensure the lay-up was fully saturated. the resin started thermosetting shortly after and was left to cure for several hours before it was ready to be cut and trimmed) socket. the mechanical strength of prosthetic sockets was investigated in accordance with iso 10328 standards. the loading configurations as specified in iso 10328 reflects loading that occurs either during heel strike (loading condition i), in which the load axis passes from the anterior side of the proximal leg to the posterior side of the distal leg, or toe-off (loading condition ii), in which the load axis passes way towards the anterior side to the distal end of the socket. condition ii is the most commonly used testing condition for ultimate failure of 3d printed sockets since it places the socket in its “worst case scenario”, where failure loads are lower due to higher bending moments generated at the distal end of the socket. our failure test results performed at condition ii with a 2inch pylon at p5 loading level (p5 load level of the iso standards, which targets patients with a body mass of 100 kg and corresponds to 920 n (settling test), 2013 n (proof test), and 4025 n (ultimate test, upper limit) for the tests) showed 3d printed composite sockets had 32% reduced ultimate failure strength when compared to laminated sockets. however, they may still be safe to use at the prescribed loading levels. based on the cumulative results of our testing and literature review, we believe that improving the pylon socket interface and inclined layer printing might help improve the strength to match that of laminate composite sockets.6 optimization of the digital workflow the implementation of the full digital workflow within our practice group has been an exciting and challenging task. our goal was to replicate the traditional process and improve both clinical and technical efficiencies. our practice is currently utilizing printing for diagnostic sockets (petg filament innovations), co-poly sockets (cpx filament innovations), and flexible inner sockets (tpumatter hackers). our clinical workflow model works as follows for our clinicians: 1. shape capture (15 minutes) a. clinician will cast patient and scan outside of fiberglass cast, as this is simpler than scanning inside of cast, and a uniform fiberglass cast is thin enough to capture limb shape and easily be modified out (75%) b. clinician will scan limb directly (15%) c. clinician will cast patient and mail cast to fabrication team (10%) ● we currently utilize structure scanners with an ipad and the willowood omega scan application (version 4.2.0) or the orten capture front camera scanners (orten 3d cam 6.0.1 (588)) on iphone. 2. digital modifications (10 minutes) a. digital technicians modify scan from clinician (85%) b. clinicians modify scan and send to digital technicians (15%) ● we primarily utilize willowood omega software (version 1.7.2 (1.7.19281.01)) for socket modification. we are currently testing ossur design studio (version unavailable) and orten fly shape (version 1.3.1 (588)). 3. digital socket design (10 minutes) a. digital technicians create sockets with desired suspension: pin lock lanyard, suction, vacuum, or sealin b. socket is entered into a slicer to create g-code for printing. we currently utilized odin (filament innovations, version 1.2.2) and simplify 3d (version 4.1.2) https://doi.org/10.33137/cpoj.v6i2.42140 4 gutierrez a.r. exploring the future of prosthetics and orthotics: harnessing the potential of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.7. https://doi.org/10.33137/cpoj.v6i2.42140 canadian prosthetics & orthotics journal issn: 2561-987x harnessing the potential of 3d printing in p&o gutierrez a.r, 2023 (special issue) note: we utilize meshmixer (autodesk version 3.5.474) for all design. 4. socket is printed and trimmed by digital technicians (1.5-2.5 hours shape dependent) a. we currently utilize filament innovations icarus printers, kratos printers, and a pva med printer for these prints. conclusion in conclusion, our initiatives have successfully provided clinicians with additional time to dedicate to patient care and improved outcomes. our ongoing endeavors are directed towards further enhancing patient care through the identification of additional procedural efficiencies. the implementation of diagnostic sockets has streamlined initial care processes and accelerated prescription timelines. notably, co-poly prints (cpx) have emerged as a reliable solution for prolonged diagnostic socket usage and preparatory devices for new individual with amputation, demonstrating sustained efficacy for up to six months. the integration of flexible prints alongside traditional lamination techniques has not only improved material consistency and reduced waste but has also been seamlessly incorporated into the production of definitive sockets. through the strategic implementation of automation, our practice has effectively lightened the time burden on clinicians, ultimately contributing to enhanced patient outcomes. call to action take proactive steps to revolutionize the field of prosthetics and orthotics through 3d printing. embrace this transformative technology to streamline workflows, reduce fabrication time, and ultimately enhance the lives of individuals in need of prosthetic and orthotic devices. collaborate with technical printer manufacturers, software developers, clinicians, and researchers to expand the capabilities of 3d printing, fostering knowledge sharing and research partnerships. invest in research and development efforts to overcome material limitations and socket strength challenges, introducing new materials and techniques validated through studies. establish and disseminate best practices for digital shape capture, design, and printing processes, standardizing workflows for reduced practitioner time and increased consistency across clinics. prioritize education and training for clinicians, equipping them with the necessary skills for effective 3d printing technology utilization. maintain a patient-centric approach, directing efforts towards improving clinical outcomes and enriching the patient experience through 3d-printed devices. together, we can unlock the full potential of 3d printing in prosthetics and orthotics. acknowledgements i extend my gratitude to sagar shetty for initiating our exploration of 3d printing, the entire bionic prosthetics and orthotics group for actively participating in the adoption of a digital clinical workflow, our digital manufacturing partners, and our patients for embracing this transformative shift in technology. declaration of conflicting interests the author is an employee of bionic prosthetics and orthotics group. sources of support this work was supported by the department of defense under the orthotics and prosthetics outcomes research program, award number w81xwh2010175. references 1.mchugh kj, nguyen td, linehan ar, yang d, behrens am, rose s, et al. fabrication of fillable microparticles and other complex 3d microstructures. science (new york, ny). 2017;357(6356):1138–42. doi: 10.1126/science.aaf7447 2.ventola cl. medical applications for 3d printing: current and projected uses. p & t. 2014;39(10):704–11. pmid: 25336867; pmcid: pmc4189697 3.mayo al, gould s, cimino sr, glasford s, harvey e, ratto m, et al. a qualitative study on stakeholder perceptions of digital prosthetic socket fabrication for transtibial amputations. prosthet orthot int. 2022;10.1097. doi: 10.1097/pxr.0000000000000157 4.rosenblatt nj, stachowiak a, reddin c. prosthetic disuse leads to lower balance confidence in a long-term user of a transtibial prosthesis. adv wound care (new rochelle). 2021;10(9):529–33. doi: 10.1089/wound.2019.1086 5.kim s, yalla s, shetty s, rosenblatt nj. 3d printed transtibial prosthetic sockets: a systematic review. plos one. 2022;17(10):e0275161. doi: 10.1371/journal.pone.0275161 6.sunjung k, sai y, sagar s, noah r. structural integrity of customdesigned additive manufactured prosthetic sockets compared to traditional sockets. available at ssrn: https://ssrn.com/abstract=4571479 author scientific biography tony gutierrez has been with bionic prosthetics and orthotics group since 2015, currently serving as their national clinical specialist for advanced prosthetic solutions. in his role, he leads the group's adoption of digital workflows and 3d printing technology, focusing on enhancing clinical research in socket design, strength testing, and adjustable above-the-knee prosthetic socket fittings. gutierrez's educational background includes a bachelor's degree in mathematics education from indiana university–purdue university indianapolis (iupui), a master's in biomechanics from the university of wisconsin, and a postgraduate certificate in prosthetics from the northwestern university prosthetics and orthotics center (nupoc). his dedication to the field is evident through past publications in biomechanics, gait mechanics, and prosthetic socket design. https://doi.org/10.33137/cpoj.v6i2.42140 https://www.filamentinnovations.com/filament https://ssrn.com/abstract=4571479 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 1 2021 research article pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i1.36833 1 pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 research article a mixed-methods study on prosthesis use among older canadians with lowerlimb amputations pousett b1, budzinski c2, labbé d3,4,5, miller wc3,4 1 barber prosthetics clinic, vancouver, british columbia, canada. 2 holy family hospital, providence health care, vancouver, british columbia, canada. 3 department of occupational science and therapy, faculty of medicine, university of british columbia, vancouver, british columbia, canada. 4 rehabilitation research program, vancouver, british columbia, canada. 5 department of disability and human development, university of illinois at chicago, chicago, illinois, usa. introduction in 2011, 7708 lower limb amputations (lla) were performed in canada, largely on individuals between the ages of 5074 (54.9%) due to complications from diabetes (65%).1 more than half of these amputations were major amputations (from ankle disarticulations to pelvis amputations) with transtibial amputations being the most common (30.9%).1 however, only approximately 20% of individuals with major amputations received inpatient rehabilitation, which provides multidisciplinary care to help integrate the prosthesis into their daily life to improve functional mobility and social participation.2 moreover, prosthetic rehabilitation requires significant health care and economic investments, especially for older adults3 thus increasing interest in exploring the breadth of prosthetic use after discharge both in terms of quantity (e.g. wear time) and quality (e.g. type of use, experience).2,4 how prosthetic use is defined varies between different studies. its definition ranged from wear time, functional activity, participation in community or employment, and the open access volume 4, issue 1, article no.10. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: the prevalence of lower-limb amputations (lla) in older adults is increasing. due to the substantial resources required for rehabilitation, there is growing interest in exploring prosthesis use as well as the factors that impact use for individuals with lla. objectives: to examine how older adults, those over 50 years old, with a new lla use their prostheses following rehabilitation and to identify factors that increase or decrease prosthesis use after discharge from a rehabilitation hospital. methods: the stepwatch activity monitor, the prosthetic profile of the amputee questionnaire, and a semi-structured interview were used to measure prosthesis use and factors affecting use at 12 weeks post-discharge from a rehabilitation hospital. descriptive statistics were calculated for the quantitative data and the qualitative interviews were analyzed using the international classification of functioning and disability. results: two user profiles emerged from the 11 participants’ use patterns. the regular users integrated their prosthesis into their lives, using it for various types of activities, while the strategic users wore their prosthesis to perform specific activities of daily and instrumental activities of daily living tasks. body functions (e.g., pain), personal (e.g., feeling of independence), and environmental factors (e.g., home adaptations or social support) impacted prosthesis use. conclusions: the emergence of profiles suggests variability in how older adults with lla use their prosthesis after rehabilitation. however, the factors affecting prosthesis use were similar between the profiles. therefore, while it is important for rehabilitation teams to consider patients’ individual needs when setting goals for prosthetic training, they must also consider common factors affecting prosthesis use. article info received: june 26, 2021 accepted: august 6, 2021 published: august 16, 2021 citation pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1. 36833 keywords prosthesis, rehabilitation, lower limb amputation, prosthetist, older canadians, amputation * corresponding author william c miller, university of british columbia, vancouver, british columbia, canada. e-mail: bill.miller@ubc.ca orcid id: https://orcid.org/0000-0003-3060-0210 https://doi.org/10.33137/cpoj.v4i1.36833 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i1.36833 https://doi.org/10.33137/cpoj.v4i1.36833 mailto:bill.miller@ubc.ca https://orcid.org/0000-0003-3060-0210 2 pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 issn: 2561-987x prosthesis use among older canadians with lower-limb amputations pousett et al. 2021 cpoj number of steps taken.5-11 moreover, the way it is measured varied between studies. quantitative studies have used activity monitors,5,6 functional performance measures,8,10 self-reported wear time,7,8 and validated questionnaires7-10 to measure prosthesis use, while qualitative studies focused more on the type of activities done with the prosthesis, quality of life, and the experience of the prosthesis users.4,11-14 the quantitative studies measured prothesis use at different times ranging from discharge to 15 months after rehabilitation and their results varied both in terms of the quantity and quality of prosthesis use.7-14 for instance, some studies found a declined of use6,10 restricted functioning in mobility,10 leisure and social role such as employment,8,9 and limited autonomy outdoors while others7-8 reported increase prosthesis use overtime and higher functioning in activities of daily living. a qualitative meta-synthesis13 of the literature reported that most studies focused on adaptation to the amputation and the prosthesis, the role of social relationships, and the impact of the prosthesis on identity. however, how individuals use their prosthesis in specific life contexts, and the meaning of living with a prosthesis has not been fully been examined.14 moreover, only a few studies10,11 combined quantitative measure of use with the qualitative study of the experience and meaning of living with a prosthesis, which likely provides a more nuanced understanding of prosthesis use. age has been identified as an important factor affecting prosthesis use.7,15 research has suggested that prosthesis use is influenced by a variety of factors associated with aging. these factors include multiple comorbidities, cognitive impairment, compromised vasculature to the amputated side, significant deconditioning, and fear of falling.3,11,16 for instance, webster et al.7 identified that adults older than 55 years old with lla experienced greater functional restrictions and increased psychological distress than younger individuals. however, many studies only measured self-reported wear time, which did not reflect accurately the activity level.17 in addition, these studies did not always collect information about the lived experience of older users, or in what context the prosthesis was used which would help to understand how to support their prosthesis use, that might be different than for younger users. a systematic review concluded that many older prosthesis users demonstrated improved mobility in their home environment, but that more research was needed regarding prosthesis use of older adults in the community.3 to better understand the context prosthesis use, it is important to document the factors that impact it. the individual and environmental factors affecting prosthesis use have been explored in literature, albeit mostly with qualitative studies. findings generally suggest that those with increased independence and confidence tended to use their prosthesis more.10,12,15,18-20 additionally, factors such as support from family and friends, a multidisciplinary healthcare team approach, a strong patient/prosthetist relationship can all positively influence prosthesis use.7,10,12,20 conversely, the presence of pain, multiple comorbidities, impaired balance, decreased cognitive function, emotional challenges, and low daily requirements for standing/ambulating could reduce prosthesis use.9,12,19 moreover, one recent study conducted in australia20 suggested that terrain, climate, and transport systems could contain barriers to community walking for prosthesis users of all ages. however, such factors have not yet been explored in a canadian context, which has different physical environments and rehabilitation systems. moreover, studies included individuals with amputations of all ages and did not necessarily address factors that were unique to older adults with amputations.15,21 purpose of study building on previous research,10,11 this study used a mixed method approach to examine both prosthesis use quantitatively and the lived experience of older adults, defined to be over the age of 50. it also sought to identify personal and environmental factors that increase or decrease prosthetic use in the community after discharge from a rehabilitation program. this mixed method approach provides a deeper and more nuanced understanding10 of prothesis use by older adults with lla. methodology study design this study employed a mixed methods approach to examine prosthesis use, including the frequency of steps taken by participants, how they use their prosthesis and their experience of using a prosthesis. the research ethics boards of the university of british columbia ethics review committee approved the study protocol. participants participants were older adults with lla who were completing inpatient prosthetic rehabilitation at a canadian rehabilitation hospital. participants had to: 1) be over 50 years of age when they acquired their amputation, 2) have a unilateral transtibial or transfemoral amputation, 3) be fitted with their first prosthesis, 4) be participating in the individualized inpatient prosthetic rehabilitation program, and 5) speak english or be able to participate using an interpreter. the age inclusion criteria was chosen because more than half of the people with llas in canada are between ages 50–74 and they often present comorbidities associated with aging.1 all eligible participants had recently acquired their amputation and had been assessed by an interdisciplinary team, consisting of a physiatrist, physiotherapist, occupational therapist, social worker and prosthetist, and deemed to be a prosthetic candidate. https://doi.org/10.33137/cpoj.v4i1.36833 3 pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 issn: 2561-987x prosthesis use among older canadians with lower-limb amputations pousett et al. 2021 cpoj participants who were not deemed to be a prosthetic candidate were not included in this study. eligible inpatients were invited to participate through a brochure and those interested met with a physical therapist (second author) for more information. informed written consent was provided by all participants. data collection data were collected from the week prior to discharge (t0) to 12 weeks after discharge (t2). data collection included demographic and medical information, the stepwatch activity monitor (modus health washington, usa), the prosthetic profile of the amputee questionnaire,22 and individual semi-structured interviews. the stepwatch activity monitor (sam) (modus health washington, usa) was used to objectively measure prosthesis use midway through the study (t1) and at 12 weeks post discharge from inpatient rehabilitation (t2), as it was anticipated that users had then acclimated to living in their home environment. these data included the number of steps per day, minutes of active prosthetic use, and the number of days steps occurred on for each participant. the stepwatch was placed on the participant's prosthesis (around the distal pylon) at t0 and collected data until it was removed at t2. data were downloaded at six weeks (t1) as the stepwatch can only store 50 days of data. the stepwatch was chosen as it is an accurate tool for measuring step count and activity over an extended period of time for people with a variety of conditions.23-25 the reliability and validity of the stepwatch have been established for people with amputations and it has been found to be over 99% accurate.26,27 the prosthetic profile of the amputee questionnaire (ppa)22,28 is comprised of 44 closed-ended questions, divided into six sections. the ppa was administered at t0 and t2. information from the ppa was used to complete the medical records on physical conditions and the prosthesis (q1-9), home environment (q24-30), and other demographics such as level of education and occupation (q40-44). the ppa was also used to measure prosthesis use, which includes activities done with the prosthesis, the wear time, and the reasons affecting prosthesis use (q1017). finally, the ppa questions on the use of the prosthesis for leisure and social activities (q34 to 39) at t2 was used to complement the information gathered during the interviews. some questions of the ppa did not apply to the participants in this study (i.e., q22-23 are only completed if the individual does not use a prosthesis) while others were redundant (i.e., both the stepwatch and the ppa (q12) record how many days a week the prosthesis is worn) and were not included in the analysis. the ppa has an excellent test-retest reliability (between 0.80 and 0.92).29 it was administered in person or over the phone. the ppa was pilot tested with two older adults with lla to verify if using the self-completed online version was an option. they had a hard time completing it by themselves and left many questions blank, the team thus decide to use the paper version in person. pilot test data were not included in the analysis. the semi-structured interview was conducted at t2 to learn more about the participants’ experience with prosthesis use. the interview was developed by the research team and it was piloted with two older adults with lla. the pilot data were not included in the analysis. the interview was conducted by the third author who has extensive qualitative expertise. the interview included open-ended questions to explore: 1) the activities the participant was using their prosthesis for (e.g., “can you share with me what your typical day looks like? can you please share with me what it is like for you to wear a prosthesis?”); 2) the personal and environmental factors facilitating or hindering these activities (e.g., “are there are certain things that encourage you to wear your prosthesis more?”); and 3) participants’ experience with the rehabilitation professionals (“since going home have you had any outpatient physiotherapy? if yes, how were these visits helpful?”). the interviews were conducted at t2 with each participant either in person (n=8) or over the phone (n=3). they were audio recorded and lasted between 20 to 40 minutes. demographic and medical information was extracted from hospital medical records, including age, sex, marital status, comorbidities, amputation level, length of stay, residence type, and the montreal cognitive assessment (moca) scores. data analyses from the stepwatch data, the number of steps per day was calculated for the prosthetic side only, therefore the total number of steps per day is twice the stepwatch collected value. the data from the 5th week (t1) as well as the seven days before 12 weeks (t2) are presented in this paper. data from an adjacent week was chosen for two participants (#5 and #9) who were unable to wear their prosthesis for the last week of the study due to medical complications or issues with the prosthetic fit. the stepwatch also provided information on the number of days on which steps occurred, and wear patterns, particularly what time the participant first used the prosthesis, such as early morning or mid-day, and how activity was distributed throughout the day. for the questions from the ppa on the physical condition, prosthesis, home environment, demographics, and leisure activities, descriptive scores were computed based on the guidelines for this tool to provide descriptive information.22 in terms of prosthesis use, scores for question 11, which assesses independence during a variety of tasks, were calculated for both time points, where higher scores (to a maximum of 42) indicate increased independence. the scores for questions 14 & 16 were only calculated at t2 https://doi.org/10.33137/cpoj.v4i1.36833 4 pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 issn: 2561-987x prosthesis use among older canadians with lower-limb amputations pousett et al. 2021 cpoj because these questions were not applicable to inpatient rehabilitation (e.g., what percentage of the time do you use the prosthesis [inside] or [outside]?). the interviews were transcribed verbatim. a content analysis approach30 was used to identify, analyze, and interpret patterns in the participants’ responses. the first five interviews were reviewed by the entire research team and an initial coding grid was developed. the coding grid was created following the international classification of functioning, disability and health construct (icf)31 to provide codes from the domain of activities and participation to qualify the experience of prosthesis use, and from the domains of body functions and environmental factors to identify components impacting use. the coding grid also included codes for personal factors codes that were mentioned by participants but are not categorized by icf. two team members then independently coded the complete interview data set with this coding grid, added codes if needed, and discussed all coding to reach a consensus. the final coding grid was applied to all interviews. different trustworthiness strategies were used such as reflective commentary, and triangulation.32 the primary author took interview notes to reflect on the interview's context and her initial impressions and personal bias. no member checking was done. data triangulation was supported using different sources of data (interviews, questionnaires, step watch). the triangulation of different researchers' perspectives during the content analysis also helped ensure credibility. integration of data and development of profiles through a series of collaborative discussions between the research team, the entire data set was analyzed and integrated to develop two profiles reflecting prosthesis using styles of older adults with lla in their community. those profiles provide an archetypical case studies of prosthesis use that illustrate commonality found among the participants, as used in a previous study on power wheelchair use.33 to create each profile, the team grouped the participants based on information from a combination of all the data collected: the number of days worn, steps per day, and observable patterns of use were used; satisfaction and adaptation to the prosthesis and type of usage as measured by the ppa, and based on the narratives by the participants of their usage and experiences with the prosthesis as shared during the interviews. results participants between december 2015 and august 2017, 59 older adults with lla were admitted to the rehabilitation program 13 consented to participate and 11 completed the study. one participant was discharged unexpectedly and the other withdrew for medical reasons. we achieved theoretical saturation with this number of participants, which suggests we obtained a sufficient number of representative participants to answer the research question.34 the participants’ demographic and clinical information are described in table 1. the sample had an equal distribution table 1: clinical and sociodemographic characteristics of the participants. # of participants age (yrs) sex marital status education (yrs) occupation level of amputation cause of amputation total los in rehab hospital (days) prosthetic training (days) moca (on 30) 1 73 female married >12 working right tta raynauds 167 34 26 2 76 male single >12 retired left tta pvd/diabetes 100 57 28 4 87 male married 12 retired left tta pvd 117 56 16+1 5 69 male married >12 retired left tta foot deformity crps 71 30 24 6 66 female married >12 disability right tta diabetes 137 37 nt 7 66 female common-law 12 retired left tfa infected knee replacement 183 46 25+1 9 52 female single <12 retired right tta foot deformity radiculopathy 106 84 24+1 10 73 female married >12 retired left tta pvd 89 56 nt 11 66 male married 12 retired right tta pvd/diabetes 120 45 nt 12 60 male married >12 working left tta pvd/diabetes 59 29 nt 13 58 male married >12 retired right tta diabetes/ charcot foot 66 29 26/30 los = length of stay; tta = transtibial amputation; tfa = transfemoral amputation; nt= not tested; pvd = peripheral vascular disease, crps = complex regional pain syndrome ; +1 on the moca score = 12 years of education https://doi.org/10.33137/cpoj.v4i1.36833 5 pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 issn: 2561-987x prosthesis use among older canadians with lower-limb amputations pousett et al. 2021 cpoj in terms of sex (6 men,5 women), and the average age was 67.8 years old. this is very similar to the typical population of patients seen at this facility. from the ppa (q1-9; q24-30; 40-44), all participants had at least four co-morbidities with the most common being peripheral vascular disease (pvd), diabetes, hypertension, and low back dysfunction. the main problems with their non-amputated leg were swelling, poor circulation, and cramps. the main problems with the residual limb was phantom pain and a few participants (4 out of 11) also experienced occasional pain. the majority of participants (9 out of 11) were quite well or completely satisfied with the comfort, appearance, and weight of their prosthesis as well as the appearance of their gait while using it. however, they experienced some issues with their prosthesis—mainly skin irritation and excessive stump perspiration. all the participants lived in a house or apartment, with half of them having no stairs in or outside their home. are older adults with lla using their prosthesis? all individuals in this study used their prosthesis regularly, though wear patterns differed between participants. the daily average number of steps taken on the prosthesis at t2 ranged from 481 to 3031 (figure 1). some participants walked with their prosthesis every day while others had several days where no steps were taken (figure 2). it should be noted that one participant (#11) experienced a foot injury towards the end of the study, resulting in a day in which there was a large decrease in steps. for one participant (participant 2), there were several days where the stepwatch was put on the prosthesis upside down and data were not recorded. figure 1: daily average number of steps on the prosthesis at t1 (black) and t2 (grey). table 2 presents the use of the prosthesis based on the ppa. first, a mobility score was calculated using the ppa. the mobility score represents an individual’s ability to complete a series of activities while wearing their prosthesis and how much help they required to do so. the ppa provided additional information about how participants used their prosthesis. it revealed that four participants were parttime wheelchair (wc) users, mostly inside their homes (i.e., used the wc 50 to 75% of the time). the main reasons for wc use given by the participants were other health conditions such as back or respiratory issues, and problems with the prosthesis. figure 2: number of days that participants took steps with their prosthesis. black represents days with no steps taken and grey represents days with steps taken. how are older adults with lla using their prosthesis? when considering how participants were using their prosthesis, two distinct user profiles emerged: the regular users and the strategic users. regular users regular users (participants 4, 6, 7, 10, 11, 12, and 13) had integrated their prosthesis into their lives. they wore their prostheses from morning to evening, 12 to 16 hours a day, seven days a week. the intensity of activity was consistent throughout the day and they took 400 3000 steps a day on their prosthesis. the ppa showed that regular users used their wheelchairs less to mobilize inside their homes and used their prosthesis almost exclusively for outdoor mobility. these users also reported higher levels of mobility function and independence. in the interviews, these participants emphasized the frequent use of their prosthesis through comments such as “i put it on the first thing in the morning and i take it off the last thing at night” (#7, a 66 year-old female with a left tfa). the regulars users wore their prosthesis for a variety of activities: mobility, self-care, and domestic life. in terms of mobility, they used their prosthesis to walk short and long distances, moving around in and outside their homes, “i haven’t had a chance to go for a field run with my new prosthetic from yesterday, but i was up to being able to hit about 3, 4 kilometers before that was enough for me for a day” shared #12, 60 years-old male with a left tta. participants also mentioned regularly wearing their 0 500 1000 1500 2000 2500 3000 3500 1 2 4 5 6 7 9 10 11 12 13 # p ro s th e ti c s te p s p e r d a y participant # prosthesis use 3 months post discharge 0 10 20 30 40 50 60 70 80 90 1 2 4 5 6 7 9 10 11 12 13 # o f d a ys participant # number of days steps were taken on prosthesis no steps taken steps taken https://doi.org/10.33137/cpoj.v4i1.36833 6 pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 issn: 2561-987x prosthesis use among older canadians with lower-limb amputations pousett et al. 2021 cpoj prosthesis to conduct self-care activities such as toileting and dressing. in terms of domestic life, they used their prosthesis when preparing meals or cleaning. regular users also conducted community, social, and civic life activities such as shopping, going to the restaurant, or the church using their prosthesis. for instance, one 73 years old women with a left tta (#10) explained “i will do some sewing, or i will play the piano […] i’ll try to do a little walking in the back garden if the weather is good, or i will do my exercises. and in the afternoon […] if the weather is not too bad, we’ll go out for a walk… usually, we’re outside for maybe an hour and a half and then we stop sometimes to the grocery store on the way back”. the regular users were using their prosthesis both for sports (e.g. golf, curling, yoga) and leisure activities (e.g., arts and crafts or gardening) as seen in their answers to the section on leisure activities in the ppa and their narratives from the interviews. the regular users began to see their prosthesis as part of themselves, as one participant said (12, man, 60 years old, with a left tta) “me and my legs are the same things.” strategic users strategic users (participants 1, 2, 5, and 9) viewed their prosthesis as a tool to complete specific tasks and activities. they used their prosthesis for shorter intervals throughout the day: three to seven days a week. from the ppa, these individuals frequently mobilized with a wheelchair inside their homes (>50% of the time) but outdoor wheelchair use varied. finally, these users reported lower levels of mobility function and independence. during the interviews, the strategic users explained that they donned their prosthesis later in the day or used it only for specific mobility activities such as short distance walking (often as part of their exercise regime) and walking inside the home. they rarely used their prosthesis to move around outside their homes. the strategic users also put on their prosthesis for specific self-care activities such as taking care of their health by attending physiotherapy appointments. they also used it for specific domestic life activities such as doing the dishes. they did not use their prosthesis to participate in their social or community life. for instance, one participant (#1, female 73 years old with a right tta) explained: “today i put it on at 10. it depends what i’m doing, if i’m going out. i don’t usually wear to work[…] i take it off for a while and then put it on back on because it gets a bit sweaty at times […] in the afternoon”. sometimes stump swelling sometimes forced participants to remove their prosthesis. some participants indicated they developed a preference for their wheelchair: “there is nothing so cozy and comforting as a wheelchair” (#2, a 76 year old male with a left tta ). what factors influenced prosthesis use? in the interviews, participants identified personal and physical and social environmental factors that limited or increased their prosthesis use. those factors did not distinguish between the strategicand the regular users; some factors were described as facilitating use by some participants but as limiting use by others, while other factors were identified as both facilitators and barriers by all participants albeit their type of use. regarding personal factors, the feelings of normalcy and increased independence associated with wearing the prosthesis facilitated prosthesis use. one participant (#4, an 87-year-old male with a right tta) said, “the prosthesis gives me the freedom to do things”. some participants had not yet experienced those feelings but mentioned that regaining their independence and being “normal” again table 2: select questions from the prosthetic profile of the amputee questionnaire. q.11 mobility function score (max score of 42) q. 14 indoor mobility (t2) (%) q. 16 outdoor mobility (t2) (%) no. in hospital (t0) at home (t2) in w/c walking with prosthesis walking without prosthesis in w/c walking with prosthesis walking without prosthesis 1 22 24 75% 0% 25% 100% 0% 0% 2 24 32 75% 25% 0% 0% 100% 0% 4 33 31 25% 75% 0% 0% 100% 0% 5 27 42 50% 50% 0% 0% 100% 0% 6 31 33 25% 75% 0% 0% 100% 0% 7 36 40 0% 100% 0% 0% 100% 0% 9 42 41 50% 50% 0% 50% 50% 0% 10 32 41 0% 100% 0% 0% 100% 0% 11 42 42 25% 75% 0% 25% 75% 0% 12 40 42 0% 100% 0% 0% 100% 0% 13 33 39 0% 100% 0% 0% 100% 0% t0 = 1 week prior to discharge, t2 = 12 weeks post-discharge, w/c = wheelchair https://doi.org/10.33137/cpoj.v4i1.36833 7 pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 issn: 2561-987x prosthesis use among older canadians with lower-limb amputations pousett et al. 2021 cpoj motivated them to wear their prostheses. on the other side, co-morbidities such as diabetes or cardiorespiratory problems were cited as barriers to prosthesis use by all participants. the factors of the physical environment concerned the assistive technologies and the home environment (product and technology) and climate and weather (natural environment). regarding assistive technology, the older adults mentioned that using a cane or a walker aided walking with the prosthesis. the participants also felt that the prosthesis facilitated use when it was fitting well, but was a barrier when it was uncomfortable due to poor fit or poor sock management. the location of the home was a facilitator. for instance, one participant reported using more the prosthesis because of the surroundings of his home “we live on a hillside. so there is just no way that i would be able to use the wheelchair for very much outside” (#12, man, 60 years old, with a left tta). housing modifications made to increase accessibility were also reported as facilitating prosthesis use, especially bathroom adaptations such as handrails and shower benches, or having an elevator inside the residence. conversely, home feature such as stairs were limiting prosthesis use. inclement weather such as snow and rain, was perceived as a barrier. participants said they wished they would have been trained to walk in those conditions with their prosthesis. in terms of the social environment, receiving support from friends and family was a factor that promoted prosthesis use. one woman (#7, 66 years old with a left tfa) explained during her interview “oh, my girlfriends, they always say, ‘oh my gosh, this is the best thing’ and they say ‘you’re really good’.” regarding health care services, systems and policies, the participants perceived that the informational and emotional support provided by the healthcare professionals such as the physiotherapists and prosthetists facilitated their prosthesis use. for instance, they perceived their inpatient training as useful—participants appreciated the reinforcement they received about their progress. one older participant said “they are teaching you how to stand up straight and learn to walk. and then finally you are walking. and you are walking around the gym. and those things are very important […] psychologically important, because they are teaching you that the things can still be as they were. you don’t have to spend the whole rest of your life in a wheelchair.” (#4, an 87-year-old male with a right tta). the rehabilitation professional’s attitude and knowledge also motivated participants to use their prosthesis. participants emphasized that advice regarding sock management and how to adjust their prosthesis fit was particularly helpful. discussion this study used a mixed-method approach to examine how older adults with lla use their prosthesis following rehabilitation and to identify factors that increase or decrease prosthetic use after discharge. the creation of the profiles of use, “regular user” and “strategic user”, allowed for a holistic portrait of prothesis use by older adults with lla. all of the participants in this study used their prosthesis, as measured with step counts, which aided their goals. more than half of the participants took approximately 500 steps per day on their prosthesis which is below the “basal” activity level threshold for older adults.35 the regular users achieved more than 1,250 prosthetic steps per day, which is considered a “sedentary” activity level, only two achieved the “limited”35 activity level by walking over 2,500 prosthetic steps per day. while step count is known to fluctuate for reasons secondary to personal and environmental factors including seasonal changes, health status, prosthetic fit, and life situations, it gives a snapshot of prosthetic use at a given time point.5,6,10 the 5 most active participants took about 3000 total steps per day, which is similar to other studies that found that adults of all ages with lla or those with diabetes averaged more than 3000 steps per day (3 months after discharge from rehabilitation).17,36 despite their variability in use, all the participants improved their mobility during the time of the research. this is similar to other research that found that prosthesis use in older adults, as measured by reported wear time, increased over time post amputation.11,16 individuals may need more time to experience using the prosthesis in their home environment before truly understanding how they may integrate it into their life, suggesting the importance of considering a long term follow-up (e.g., at least 6 months) in the rehabilitation process.4 currently, outpatients with lla in canada receive four to six weeks of outpatient rehabilitation, a period when the prosthesis still needs adjustments and is not regularly used as our results suggest.2 tools like the ppa22 could also be used when the prosthesis user returns for outpatient follow-up to have a more complete and objective outcome measure. moreover, multiple follow-ups could help older users with lla consolidate their training by repeating information or discussing problem solving, which could be especially important as older users may experience decreased cognitive functions.19,21 the two user profiles, distinguished how participants used their prosthesis in their daily lives. the identification of variance in prosthesis use is similar to previous studies that reported heterogenous use patterns after discharge.7,16 for instance, when examining older patients with lla one year post-discharge from a rehabilitation program, hershkovitz et al.16 found a distribution including three groups: full time use (e.g. most of the days), part time use, and no use. using mixed methods to identify the strategicand regular user profiles allowed us to explain the identified pattern of use https://doi.org/10.33137/cpoj.v4i1.36833 8 pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 issn: 2561-987x prosthesis use among older canadians with lower-limb amputations pousett et al. 2021 cpoj quantitatively by referencing step count and the ppa, as well as qualitatively by exploring lived experiences during interviews. for instance, while the stepwatch revealed that regular users were wearing their prosthesis more and taking more steps throughout the day, the ppa and interviews confirmed that they used their prosthesis for all their activities. moreover, they perceived their prosthesis as a part of their bodies which suggest a higher level of integration.13 on the other hand, the shorter periods of activity found with strategic users’ stepwatch data was mostly due to the fact that they used their prosthesis for targeted basic activities of daily living (e.g., going to the bathroom) or exercise (e.g. walking short distances) as explained by the interviews data. the identification of user profiles suggests that rehabilitation professionals could focus on individualized goals of older adults with lla, as proposed in recent studies.11,20 it suggest the need to incorporate various types of training such as ambulating outdoors on uneven ground, ramps, and stairs into rehabilitation programs to improve mobility outside of the home environment – a rewarding experience for many individuals which helps to establish a sense of normalcy.11 working on individualized goals also mean that the rehabilitation professional discusses community participation needs20 with prosthesis users. currently in canada, few rehabilitation facilities offer return-to-work or recreational therapy that could support these needs.2 this study reported several personal and social environment factors that help the older adults using their prosthesis. as the older adults progress through their rehabilitation and increase their mobility, they gained confidence and reported an increased sense of freedom and independence, similar to users of all ages in previous studies.4,18 this was especially true for the regular users who integrated their prosthesis into their daily lives and were beginning to see it as part of their body. this feeling of normality and freedom might be a goal for some older users but not necessarily for all. it is thus important for the prosthesis user and other rehabilitation professionals to discuss what normality and independence mean for the users to better support them to reach their “new normal”.14 as has been found for younger prosthesis users,6,10,12,18,20 support from family and friends positively affect the transition to being a prosthesis user in older age. this suggests that including family and/or caregivers in rehabilitation may be a valuable way to build a support network for the individuals to continue using the prosthesis after being discharged.12 facilitating peer support from those who have already made positive adjustments to amputation and prosthesis use could also be more integrated into the rehabilitation process.13 it could show older adults with lla what is still possible for them to do and to identify goals for themselves that they might not have thought of. our research also supports similar studies showing the importance of regular follow-ups with prosthetists. follow-ups helped increase prosthesis comfort and allowed participants to develop a relationship with their prostheses, factors that facilitate use.10,12,18 several personal and physical environmental factors were identified that limited older adult participants from using their prosthesis. some of these factors such as discomfort in the socket or challenges with outdoor mobility could be mitigated by regular follow-ups with the rehabilitation team. our study also underlined the impact of inclement weather, such as rain, ice, and snow, adding to previous literature only reporting heat as a climatic barrier.9,20 this is especially relevant to individuals who completed their rehabilitation during the summer months with no exposure to wet or slippery environments that are common in canada and other countries with a similar range of weather patterns. it reaffirms the importance of long-term follow-up rehabilitation to assure that patients do not miss out on community outings due to a lack of seasonal preparation. as argued by vantwiller et al,10 it is inevitable that patients will encounter barriers. however, individual reactions to these perceived barriers could greatly vary. therefore, it would be helpful to teach older prosthesis users about positive coping strategies to deal with problematic situations, to support their prosthesis use.13 limitations the limitations of this study include the sample being a small number of participants from a single rehabilitation setting. this limits the ability of these findings to be applied to other settings and populations. collecting data from different rehabilitation settings would provide evidence regarding the applicability of these results in other settings. more specifically, this study only includes one participant with a transfemoral amputation and as such the findings are not generalizable to the transfemoral population. in addition, while this study followed participants in depth for the first 12 weeks after discharge from rehabilitation, nothing is known about the participants’ long-term prosthesis use. collecting additional data (e.g., six months and two years post discharge) could produce rich evidence in the long-term benefits and needs of rehabilitation programs. future research could also look at individuals from communities where resources and support are limited such as rural communities, or from different cultural backgrounds to see if they have a different pattern of use. conclusion the results of this study showed that older adults with lower limb amputations are using their prosthesis, but also that there is variability in how they are integrated into their daily lives. the older adults in both the regular and strategic users profiles, used their prosthesis to complete basic and instrumental activities of daily living. however, differences existed in how the prosthesis is used during community and https://doi.org/10.33137/cpoj.v4i1.36833 9 pousett b, budzinski c, labbé d, miller wc. a mixed-methods study on prosthesis use among older canadians with lower-limb amputations. canadian prosthetics & orthotics journal. 2021;volume 4, issue 1, no.10. https://doi.org/10.33137/cpoj.v4i1.36833 issn: 2561-987x prosthesis use among older canadians with lower-limb amputations pousett et al. 2021 cpoj social activities. moreover, factors impacting use were similar across the profiles. therefore, it is important for rehabilitation teams to work with their patients to recognize potential barriers and provide the tools to problem solve around them, especially once patients can walk and are focusing on higher level activities. follow-up with the rehabilitation team once the patient is discharged could help ensure the patient’s prosthesis is comfortable and also address new concerns that may arise from prolonged use of the prosthesis at home and in community environments. acknowledgements the authors would like to thank the other members of the research team including jami bennett, stacey cave, ashley plough, leah swantje dr. elliot weiss, and alison hoens (mentor). we would also like to thank aggie black and her team at the phc research challenge; zoe greig, kate keetch, and laura beer for their administrative assistance, and providence health care and barber prosthetics clinic for supporting us conducting this research. declaration of conflicting interests the author(s) declare(s) that there is no conflict of interest. author contribution • brittany pousett, contributed to the study design, data management and analyses of the step watch data and writing of the manuscript and study report. • colleen budzinski, contributed to the development of the design and protocol, ethics submission, management of the research team, analyses of the data and editing of the manuscript. • delphine labbé, contributed to the recruitment, enrollment, data collection, data analyses and writing of the final paper and report. delphine labbé is now an assistant professor at the university of illinois at chicago. • william c miller, contributed to the development of the design and protocol, management of the research team, administrative support, analyses of the data and editing of the manuscript. sources of support this work was supported by the providence health research challenge. ethical approval this study was approved by the university of british columbia ethics review committee. references 1.imam b, miller wc, finlayson hc, eng jj, jarus t. incidence of lower limb amputation in canada. can j public heal. 2017; 108: e374–e380. doi:10.17269/cjph.108.6093 2.imam b, miller wc, finlayson hc, eng jj, jarus t. lower limb prosthetic rehabilitation in canada: a survey study. physiother can. 2019; 71: 11-21. doi:10.3138/ptc.2017-39 3.fortington lv, rommers gm, geertzen jh, postema k, dijkstra pu. mobility in elderly people with a lower limb 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35.tudor-locke c, craig cl, aoyagi y, bell rc, croteau ka, de bourdeaudhuij i. how many steps/day are enough? for older adults and special populations. int j behav nutr phys act. 2011; 8: 80. doi:10.1186/1479-5868-8-80 36.desveaux l, goldstein rs, mathur s, hassan a, devlin m, pauley t, et al. physical activity in adults with diabetes following prosthetic rehabilitation. can j diabetes. 2016; 40: 336-341. doi:10.1016/j.jcjd.2016.02.003 https://doi.org/10.33137/cpoj.v4i1.36833 https://www.who.int/standards/classifications/international-classification-of-functioning-disability-and-health https://www.who.int/standards/classifications/international-classification-of-functioning-disability-and-health all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 2 2024 research article johannesson a, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i2.44089 1 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 research article evaluation of the swedeamp database: focus on coverage and amputation level rates johannesson a.g1 *, scheving r2, westlund k.l2, fridriksson t2 1. össur clinics emea, stockholm, sweden. 2. össur iceland ehf., r&d, medical office, reykjavik, iceland. introduction national patient registers collect data on diseases and treatments within specialized care, covering all inpatient admissions and outpatient doctor visits in these setting. a register can be used to monitor long-term health trends in the population, improve the prevention and treatment of diseases, contribute to the development of health care, and monitor the quality of health care services.1 in lower limb amputation (lla), this can be the only practical option to evaluate the selection of amputation level due to ethical considerations, cost, and practicality. in developed countries, elderly and often frail populations are the main subject to amputation due to vascular disease and are rarely included in scientific studies that can evaluate different treatment options.2 open access abstract background: the national board of health and welfare manages several national registers in sweden. this includes the swedish national inpatient register (ipr), covering all surgical operations, and swedeamp, focusing on outcomes after lower limb amputations (lla). however, coverage rates of amputation levels between these registers have not been externally analyzed. objective: to compare swedeamp's coverage with ipr for lla cases and to assess swedeamp's accuracy in capturing lla data. the goal of this study was also to identify potential discrepancies and establish benchmarks for common amputation levels. methodology: data from both registers, covering the years 2018 to 2023, were compared regarding the amputation levels and patient demographics. the coverage rate of the swedeamp register was calculated using swedeamp data as the numerator and ipr data as the denominator. findings: the ipr registry recorded 10,788 llas across 21 regions (67 hospitals). the swedeamp documented 5,246 llas covering 17 regions (36 hospitals), leaving 5,542 amputations unaccounted for, mainly due to regions or hospitals not participating in the swedeamp registry and lower registration rates in some areas. key findings include: • achieving full coverage in swedeamp (17 regions) would require registering 9,305 llas. • both men and women over 85 years were significantly underrepresented. • thirteen regions in swedeamp obtained more than 40% coverage rate. • 5 regions had more than 50% rate of above-knee amputations (range: 50.9% 68.2%). • 8 regions reporting more than 50% rate of below-knee amputations (range: 53.1% 88.9%). • among the 67 hospitals performing llas, 36 reported to swedeamp. six of these hospitals performed fewer than 10 llas over a six-year period. conclusion: swedeamp captured 48.6% of initial llas in sweden, highlighting the need for improved data completeness in lla records, especially as only 13 regions achieved over 40% coverage. for hospitals performing regular amputation, the proposed benchmark coverage of ≥60%, with ≤36.3% for transfemoral amputation (tf), ≤8.4% for knee disarticulations (kd), and ≥55.3% for transtibial amputations (tt) – could serve as a target to enhance consistency and accuracy in reporting. expanding coverage can improve the register's utility in tracking outcomes, setting national standards, aiding research, and supporting clinical decision-making. article info received: october 8, 2024 accepted: november 12, 2024 published: november 19, 2024 citation johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 keywords amputation, rehabilitation, lower limb amputation, swedeamp, amputation rates, sweden, transfemoral, transtibial, knee disarticulation definitions/abbreviations ak/bk ratio: the ratio of above-knee (ak) amputations (tf+kd) to below-knee (bk) amputations (tt) within a given population. initial limb amputation: the first lla surgery on a person's limb. ipr: the swedish national inpatient register. ncsp: nordic classification of surgical procedures (swedish version). scb: statistics sweden (official governmental statistics). swedeamp: the amputation and prosthetics registry for the lower limb. lla: lower limb amputation. kd: knee disarticulation. tf: transfemoral. tt: transtibial. * corresponding author: anton g. johannesson, phd, cpo össur clinics emea, stockholm, sweden. e-mail: ajohannesson@ossur.com orcid id: https://orcid.org/0000-0001-8729-458x journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 2, article no.2. 2024 https://doi.org/10.33137/cpoj.v7i2.44089 https://doi.org/10.33137/cpoj.v7i2.44089 mailto:ajohannesson@ossur.com https://orcid.org/0000-0001-8729-458x https://orcid.org/0000-0001-8729-458x https://jps.library.utoronto.ca/index.php/cpoj/index 2 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 around the year 2000, swedish authorities recognized the importance of using registers for quality control in healthcare. as a result, they began supporting the creation of new registers and established structured methods for financing and certifying these registers. this initiative has led to the development of over 100 healthcare registers.3 the national statistical agency, the statistics sweden official governmental statistics (scb), covers a wide range of areas, such as demographics, economics, education, and labor for sweden.4 this also includes the swedish national board of health and welfare (socialstyrelsen) registers, responsible for regulating and supervising healthcare and social services across sweden, ensuring quality and safety.5 it has administered several national registers since the start of inpatient data collection in 1964 and nationwide registration since 1987 to facilitate swedish healthcare and social services analysis and development.6 the register's production and quality are monitored, and reports on the quality are published regularly.7 this and other swedish registers are based on the swedish personal identity number as an identifier. one of them is the swedish national inpatient register (ipr), which includes a broad range of surgical operations (llas included) performed in sweden since 1998.8 ipr uses the swedish version of the nordic classification of surgical procedures codes (ncsp) for registration.9 it offers data on the number of surgeries performed, including llas divided into sex, age groups, and patient demographics. in orthopedics, the swedish knee arthroplasty register was initiated in 1975 and was the first national register to monitor the outcome of a specific orthopedic surgical procedure. the swedeamp register,10 funded by the swedish association of local authorities and regions, supports sweden's municipalities and regions in delivering public services, including healthcare. the swedeamp register tracks data related to lla, including limb loss due to vascular diseases, trauma, infections, and cancer. they focus specifically on rehabilitation with prostheses and collecting detailed data on: • amputation levels, • postoperative treatment, • prosthetic fitting, and • functional outcomes, published in a yearly report.11 the coverage of this register has improved since it started in 2011, from 16 hospitals covering patient data to include 36 hospitals (out of 67 that perform lla) in 2023. although not a nationwide register, it is currently the most extensive database related to lla and outcomes globally and is published yearly.12 the swedeamp register has already shown sex differences concerning amputation level, diagnosis, and age, leading to the conclusion that women have worse preconditions for successful prosthetic mobility after lla.13 however, the coverage rate has not been fully validated. the scottish physiotherapy amputee research group has made comparative register attempts14 reporting on llas in scotland since 2015, and the latest report is from 20202021 (a survey of the lower limb amputee population in scotland 2020 and 2021 public report). these can only be ordered through their website, and their data have not been externally evaluated. in the us, there is a plan by the mayo clinic to establish a limb loss and preservation registry to collect information to improve prevention, treatment, and rehabilitation efforts related to limb loss, but no data has been published.15 a recent swedish study by jarl et al. highlighted the need for a register to monitor llas. the study showed a national decline in lla incidence (2008-2017) across most levels, except for partial foot amputations. only 9 of 21 regions saw a combined decrease in llas, suggesting regional variations that merit further study, especially in below-knee vs. above-knee amputations.16 another study by this group found higher lla risks among elderly males with diabetes.17 one crucial example of how swedeamp data can be used is understanding the impact of the selection of amputation levels and how it affects rehabilitation outcomes. for instance, losing the knee joint, as seen in above-or throughknee amputations, significantly affects the function when a person is rehabilitated and uses a prosthesis.18,19 the knee joint is critical when it comes to mobility, balance, and life quality.20 its absence requires patients to rely more heavily on the hip for movement, leading to slower walking speeds and increased energy expenditure.21 the ak/bk ratio can reveal surgical outcomes between clinics or regions. however, choosing the appropriate level depends on expertise, experience, and rehabilitation planning. factors such as patient age and high rates of dysvascular conditions in certain areas can greatly impact both the chosen amputation level and the overall outcomes of the procedure.17,22 trauma or sarcoma-related amputations are less common in developed countries and, therefore, contribute less to the overall amputation rates.23 benchmarking is a relatively new tool for measuring and comparing outcomes, recently gaining attention in surgical practice.24 to the author's knowledge, it was first introduced in relation to lower limb amputation (lla) in 1996.25 the future of benchmarking lies in developing national and international registries to establish standardized benchmarks. these databases ensure that data collection for specific procedures remains current, objective, standardized, and comprehensive. these systems allow healthcare providers to efficiently identify and monitor benchmarked and non-benchmarked interventions, creating accurate and relevant benchmarks. naturally, this approach requires a commitment to participating in nationally approved data collection efforts.26 the next step for the swedeamp register's could be to establish benchmarking and incorporate known https://doi.org/10.33137/cpoj.v7i2.44089 3 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 confounding factors, such as age, gender, diagnosis, comorbidities, postoperative treatments, prosthetic fitting technology, and access to rehabilitation, all of which affect rehabilitation outcomes after lla. high participation and population coverage in a register are critical for establishing a valid benchmark. the coverage rate of the swedeamp register for llas is unknown, while the ipr register, however, has a high coverage but only includes intervention codes and basic demographics. this study aimed to assess swedeamp's coverage against the more comprehensive nationwide ipr and proposed a benchmark based on frequent lla levels. in subsequent studies, we plan to analyze the outcome data from the swedeamp register in more detail. methodology for this study, data from the ipr register was obtained from the period 2018-2023 from the swedish national board of health and welfare. the ipr provides open access data using the ncsp codes for registration of amputation levels (tf = nfq19, kd = ngq09, and tt = ngq19), divided into the 21 regions of sweden, five-year age groups and sex.8 additionally, we applied to the ipr register for a list of all hospitals performing these amputations. for comparison, we applied for data from the swedeamp register for the same period, utilizing their improved coverage rate and including the same parameters. cooperating with the swedeamp register, hospitals use an online portal to report to the register in 6 different forms. form 1 and 2 include all levels of lla from partial toe amputation to hemipelvectomy, and form 3–6 are solely focused on amputations at or proximal to tt amputation level13 using primarily iso definitions.27 this data also included outcome data that will be used for analysis in later studies. for data regarding age and sex, the official statistics of sweden (scb) was used.28 the aim was to cross-reference data between the two registers to identify discrepancies. in our analysis, all surgical procedures were initial lla performed on a limb. the person could, in theory, have been amputated before 1998 (before the start of the official ipr data collection), but the person occurs only once in our data sets. due to inconsistent identification, certain hospital locations were grouped together to ensure database comparability. in the swedeamp database, one ipr hospital location (halland sjukhus) was split into two separate hospitals (varberg and halmstad). statistics incidence: patient groups were divided into 5-year age intervals, except for those under 45 years old, who were grouped together due to the low incidence of lla in this demographic in sweden. the mean age-group data populations were calculated as the mean value for the population for each year of the study period (2018-2023). this data was sourced from the scb database.28 the mean amputation rates over the same period were obtained from the ipr database.8 the overall age-specific incidence rates for the initial lla were thereafter calculated. the overall incidence per 100,000 person-years was calculated as the number of individuals who had undergone initial llas divided by the corresponding total population. coverage rate the swedeamp register's coverage rate was calculated using swedeamp data as the numerator and ipr data as the denominator. benchmarking to assess the ratio of amputation levels, we compared the average coverage rates from all 36 hospitals reporting to swedeamp. to control how the coverage rate changed with regard to amputation levels we focused on those hospitals that obtained 80%, 60%, and 40% coverage rates for comparison, using the ipr data as a reference. this conclusion is based on the observation that a higher coverage rate of over 80% would involve fewer patients and hospitals, and a lower percentage (less than 40%) would be the opposite scenario. between 80% and 40% of this data formed the basis for establishing benchmark recommendations. the result is presented stepwise: • overview of the ipr and swedeamp registered material with regional coverage; • demographics of swedeamp population by region; • regional comparison between ipr and swedeamp; • coverage rate by swedeamp hospitals o comparison based on coverage rates of 80%, 60%, and 40%; • suggestion on a benchmark of amputation levels. all statistical analyses were performed using r (r version 4.3.3, r foundation for statistical computing, vienna. austria). both the swedeamp and ipr (inpatient registry) databases were filtered and processed to include only relevant information for primary amputations. various r packages were utilized for data manipulation, visualization, and statistical analysis. the tidyverse package was employed for general data manipulation and visualization tasks. the table1 package was used to create summary tables, while knitr and kableextra were utilized to render tables in a publication-ready format. for color palettes, the rcolorbrewer package was used. spatial data manipulation and visualization were achieved using the swemaps2 and sf packages. additionally, the stringr package was used for string manipulation. summary tables were created to describe the demographic and clinical characteristics of patients undergoing primary amputation in different regions. https://doi.org/10.33137/cpoj.v7i2.44089 4 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 to compare the distribution of demographic and clinical characteristics between the swedeamp and ipr databases, chi-square tests were performed. these tests assessed whether there were significant differences in the distributions between the two databases. additionally, linear regression models were fitted to examine the relationship between coverage ratios and age, as well as coverage ratios and year. this analysis helped in understanding how coverage ratios varied with these factors. using the kable and kableextra packages, summary tables were created to present data on amputation levels, gender distribution, and regional coverage. spatial maps were generated to visualize the coverage of swedeamp by county and the population distribution by region. line plots were created to show the trends in amputation type percentages based on hospital coverage rates and patient numbers. this study was approved by the regional authorities kvb (nr. 152-24),29 and by the swedish ethical review authority, dnr 2023-05222-01. results overview of the registered material with regional coverage according to ipr data, 67 hospitals across all 21 regions in sweden performed a total of 10,788 initial llas at the tf, kd, and tt levels during the study period. 6,127 (56.8%) were male, 4,661 (43.2%) were women, averaging 85 amputations per region per year (range: 16-332). sixteen of these hospitals reporting to ipr performed fewer than 10 llas over the six-year period. the swedeamp register collected data from 36 hospitals from 17 of the 21 regions on 5,246 llas during the same period. 2,994 (57.1%) were male, 2,252 (42.9%) were women, leaving 5,542 initial amputations unaccounted for in the swedeamp (table 1). according to the ipr, to achieve full coverage from the 17 regions, swedeamp should have recorded 9,305 initial amputations (corresponding to 86.3% of all llas) during the study period. table 1: a systematic overview of the registered material. ** corresponding to the total % of missing data, not the sum of the column. regional coverage a coverage map of sweden's 21 regions shows that swedeamp primarily lacks data from the northern regions and two central regions that have not yet begun registration. (figure 1). the incidence of llas included in this data (tf, kd, and tt amputation only) was 16.5 amputations per 100,000 person-years. the highest incidence rate was found in men older than 80 and women older than 85. in swedeamp, individuals over the age of 85 were significantly underrepresented (table 2). demographics of swedeamp population by region the registration revealed consistency and disparity from regions reporting into swedeamp (table 3). when three regions (uppsala, värmlands, and västerbottens region) were excluded due to low registrations, the rate of tf amputation varied between 8.8% and 56.1%, the rate of kd amputation showed variation between 4.0% and 36.0%, and the rate of tt amputation varied between 31.8% and 86.8%. however, the ratio of amputation side was similar, and the median age ranged between 73 and 79 years in these regions. men were more represented in all regions, with a ratio of 1.38/1 (range = 51.9% to 72.1%). in the ipr database, the ratio was similar, men (n = 6,127) and women (n = 4661), resulting in a 1.31/1 ratio. regional comparison the data highlights a significant disparity in clinical practice regarding the selection of amputation levels. five regions showed a higher ratio of ak amputation (östergötlands, västra götalands, blekinge, gotlands and västmanlands). the difference was most transparent in östergötlands and hallands regions in the ipr database and the swedeamp register, with similar coverage rates. ipr database data: • östergötlands region: ak/bk ratio of 1.72/1 (63.3% above-knee vs. 36.7% below-knee). • hallands region: ak/bk ratio of 0.69/1 (40.9% above-knee vs. 59.1% below-knee). while the ipr data showed östergötland favoring aboveknee amputations and halland favoring below-knee amputations, the ratios differ slightly from those reported in swedeamp. swedeamp register data: • östergötlands region: ak/bk ratio of 2.10/1 (67.7% above-knee vs. 32.2% below-knee). • hallands region: ak/bk ratio of 0.54/1 (35.0% above-knee vs. 65.0% below-knee). still, östergötland performs a far higher proportion of above-knee amputations than halland region. amputation level ipr swedeamp* missing data n % n % n % tf 4,534 42.1 1,828 34.9 2,706 59.7 kd 800 7.5 438 8.3 362 45.3 tt 5,454 50.4 2,980 56.8 2,474 45.4 sum * 10,788 100 5,246 100 5,542 **51.4 • * 12 cases excluded due to missing information. https://doi.org/10.33137/cpoj.v7i2.44089 5 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 figure 1: a: geographical maps showing the swedish population (by region). b: swedeamp coverage rate in % by regions compared to ipr. swedish population by region 0k 600k 1200k 1800k 2500k stockholm malmö gothenburg 2.45m uppsala 0.4m södermanland 0.3m östergötland 0.47m jönköping 0.37m kronoberg 0.2m kalmar 0.25m gotland 0.06m blekinge 0.16m skåne 1.42m halland 0.34m västra götaland 1.77m värmland 0.28m örebro 0.31m västmanland 0.28m dalarna 0.29m gävleborg 0.29m västernorrland 0.24m jämtland 0.13m västerbotten 0.28m norrbotten 0.25m coverge of swedeamp by county 0% 50% 100% 40.1% 2% 19.7% 87.2% 64.8% 39.8% 19.4% 83.5% 97.5% 80.3% 90.7% 58.3% 5.9% 66.2% 47.6% 56.2% 58.6% 0% 0% 0% 0% stockholm malmö gothenburg a b table 2: characteristics of the study population stratified into sex and age groups compared with the data from ipr and swedeamp (with different coverage rates). standard population incidence ipr swedeamp (100%) swedeamp hospitals with >80% coverage sex age-group average annual amputations in sweden (2018-2023) average annual population in sweden (2018-2023) amputation per 100.000 personyears % of total amputees % of total amputees % of total amputees men 0-44 22.5 2,967,692 0.8 1.3% 1.3% 1.4% men 45-49 9.3 390,037 2.4 0.5% 0.7% 0.7% men 50-54 21.7 396,103 5.5 1.2% 1.6% 1.6% men 55-59 40.5 382,253 10.6 2.3% 2.5% 2.2% men 60-64 53.7 334,992 16.0 3.0% 3.5% 3.2% men 65-69 90.7 313,105 29.0 5.1% 5.5% 5.3% men 70-74 162.5 307,995 52.8 9.2% 9.5% 9.7% men 75-79 203.7 258,017 78.9 11.5% 11.1% 11.5% men 80-84 184.3 152,914 120.5 10.4% 9.9% 9.7% men 85+* 219.3 114,181 192.1 12.3% 11.3% 10.6% sum 1008.2 5,617,289 17.9 56.8% 57.0% 56.0% women 0-44 13.8 2,789,703 0.5 0.8% 0.8% 0.8% women 45-49 8.0 324,070 2.5 0.5% 0.6% 0.8% women 50-54 9.7 330,276 2.9 0.5% 0.7% 0.7% women 55-59 18.5 319,789 5.8 1.0% 1.1% 0.9% women 60-64 25.0 285,328 8.8 1.4% 1.7% 1.9% women 65-69 47.7 273,753 17.4 2.7% 3.2% 3.4% women 70-74 89.7 277,640 32.3 5.1% 5.0% 5.4% women 75-79 122.8 240,766 51.0 6.9% 7.4% 7.3% women 80-84 136.5 159,630 85.5 7.7% 7.6% 8.2% women 85+* 296.0 170,714 173.4 16.7% 15.0% 14.5% sum 767.7 5,171,668 14.8 43.2% 43.0% 44.0% men + women 1,775.9 10,788,957 16.5 100% 100% 100% * people over the age of 85 are significantly underrepresented. https://doi.org/10.33137/cpoj.v7i2.44089 6 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 table 3: demographics of the swedeamp population by region (n = 17). the uppsala, värmland, and västerbotten regions are excluded from further statistical analysis due to their low registration rates. dalarnas region jönköpings region östergötlands region skåne region stockholms region västra götalands region (n=181) (n=294) (n=394) (n=1069) (n=798) (n=1135) amputation level tf 38 (21.0%) 103 (35.0%) 125 (31.7%) 385 (36.0%) 180 (22.6%) 527 (46.4%) kd 31 (17.1%) 19 (6.5%) 142 (36.0%) 48 (4.5%) 32 (4.0%) 51 (4.5%) tt 112 (61.9%) 172 (58.5%) 127 (32.2%) 636 (59.5%) 586 (73.4%) 557 (49.1%) amputation side left 83 (45.9%) 148 (50.3%) 189 (48.0%) 527 (49.3%) 374 (46.9%) 568 (50.0%) right 98 (54.1%) 146 (49.7%) 205 (52.0%) 542 (50.7%) 424 (53.1%) 567 (50.0%) age at amputation mean (sd) 77.9 (10.8) 76.3 (13.1) 74.9 (13.1) 75.9 (12.1) 77.3 (12.7) 76.1 (12.9) median [min, max] 79 [26, 101] 78 [24, 101] 77 [22, 99] 78 [20, 101] 79 [22, 101] 78 [21, 100] gender women 72 (39.8%) 138 (46.9%) 183 (46.4%) 447 (41.8%) 334 (41.9%) 525 (46.3%) men 109 (60.2%) 156 (53.1%) 211 (53.6%) 622 (58.2%) 464 (58.1%) 610 (53.7%) year 2018 34 (18.8%) 69 (23.5%) 58 (14.7%) 185 (17.3%) 115 (14.4%) 134 (11.8%) 2019 26 (14.4%) 63 (21.4%) 64 (16.2%) 185 (17.3%) 152 (19.0%) 217 (19.1%) 2020 29 (16.0%) 41 (13.9%) 69 (17.5%) 145 (13.6%) 130 (16.3%) 158 (13.9%) 2021 29 (16.0%) 27 (9.2%) 55 (14.0%) 161 (15.1%) 83 (10.4%) 183 (16.1%) 2022 37 (20.4%) 50 (17.0%) 77 (19.5%) 198 (18.5%) 122 (15.3%) 239 (21.1%) 2023 26 (14.4%) 44 (15.0%) 71 (18.0%) 195 (18.2%) 196 (24.6%) 204 (18.0%) blekinge region gävleborgs region gotlands region hallands region örebro region västmanlands region (n=195) (n=177) (n=81) (n=380) (n=231) (n=107) amputation level tf 103 (52.8%) 49 (27.7%) 34 (42.0%) 106 (27.9%) 62 (26.8%) 60 (56.1%) kd 11 (5.6%) 26 (14.7%) 12 (14.8%) 27 (7.1%) 16 (6.9%) 13 (12.1%) tt 81 (41.5%) 102 (57.6%) 35 (43.2%) 247 (65.0%) 153 (66.2%) 34 (31.8%) amputation side left 99 (50.8%) 91 (51.4%) 41 (50.6%) 192 (50.5%) 109 (47.2%) 57 (53.3%) right 96 (49.2%) 86 (48.6%) 40 (49.4%) 188 (49.5%) 122 (52.8%) 50 (46.7%) age at amputation mean (sd) 78.0 (11.7) 73.9 (14.1) 77.2 (11.1) 78.4 (11.1) 76.4 (10.5) 77.0 (12.7) median [min, max] 79 [21, 99] 75 [22, 98] 79 [45, 93] 79 [30, 101] 78 [41, 98] 79 [21, 98] gender women 74 (37.9%) 76 (42.9%) 39 (48.1%) 155 (40.8%) 102 (44.2%) 39 (36.4%) men 121 (62.1%) 101 (57.1%) 42 (51.9%) 225 (59.2%) 129 (55.8%) 68 (63.6%) year 2018 27 (13.8%) 9 (5.1%) 15 (18.5%) 45 (11.8%) 47 (20.3%) 12 (11.2%) 2019 34 (17.4%) 10 (5.6%) 16 (19.8%) 58 (15.3%) 44 (19.0%) 14 (13.1%) 2020 37 (19.0%) 42 (23.7%) 9 (11.1%) 62 (16.3%) 48 (20.8%) 22 (20.6%) 2021 30 (15.4%) 38 (21.5%) 7 (8.6%) 78 (20.5%) 28 (12.1%) 18 (16.8%) 2022 30 (15.4%) 31 (17.5%) 14 (17.3%) 56 (14.7%) 33 (14.3%) 21 (19.6%) 2023 37 (19.0%) 47 (26.6%) 20 (24.7%) 81 (21.3%) 31 (13.4%) 20 (18.7%) kalmar region kronobergs region södermanlands region uppsala region värmlands region (n=47) (n=68) (n=64) (n=9) (n=16) amputation level tf 17 (36.2%) 6 (8.8%) 27 (42.2%) 1 (11.1%) 5 (31.3%) kd 4 (8.5%) 3 (4.4%) 3 (4.7%) 0 (0%) 0 (0%) tt 26 (55.3%) 59 (86.8%) 34 (53.1%) 8 (88.9%) 11 (68.8%) amputation side left 25 (53.2%) 33 (48.5%) 33 (51.6%) 5 (55.6%) 6 (37.5%) right 22 (46.8%) 35 (51.5%) 31 (48.4%) 4 (44.4%) 10 (62.5%) age at amputation mean (sd) 70.3 (16.4) 75.0 (10.4) 75.8 (11.3) 65.9 (14.9) 66.9 (8.59) median [min, max] 73 [22, 94] 77 [41, 92] 77 [50, 92] 65 [44, 89] 69 [47, 81] gender women 19 (40.4%) 19 (27.9%) 25 (39.1%) 0 (0%) 5 (31.3%) men 28 (59.6%) 49 (72.1%) 39 (60.9%) 9 (100%) 11 (68.8%) year 2018 10 (21.3%) 9 (13.2%) 0 (0.0%) 3 (33.3%) 1 (6.3%) 2019 6 (12.8%) 12 (17.6%) 0 (0.0%) 1 (11.1%) 0 (0.0%) 2020 20 (42.6%) 8 (11.8%) 3 (4.7%) 1 (11.1%) 9 (56.3%) 2021 3 (6.4%) 12 (17.6%) 2 (3.1%) 2 (22.2%) 2 (12.5%) 2022 2 (4.3%) 9 (13.2%) 20 (31.3%) 2 (22.2%) 0 (0.0%) 2023 6 (12.8%) 18 (26.5%) 39 (60.9%) 0 (0.0%) 4 (25.0%) https://doi.org/10.33137/cpoj.v7i2.44089 7 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 comparison using ≥40% coverage rate data from swedeamp, from 13 regions in sweden that obtained at least ~40% coverage of the ipr register, was used for further analysis (table 4). in total, these regions in swedeamp registered 5,110 amputations (61.8% coverage), 2,901 tt (56.7%), 1,778 tf (34.8%), and 431 kd (8.4%), of which 2,907 (56,9%) were male and 2,203 (43,1%) women. the ipr registered during the same period 8,262 amputations (4,266 tt (51.6%), 3,280 tf (39.7%), and 716 kd (8.7%), of which 4,736 (57.3%) were male and 3,526 (42.7%) women. when analyzing the coverage ratio by age groups, the older the patients were, the higher the risk of not being included in the data from swedeamp (figure 2). the hospital coverage ratio by year showed that despite the impact of the pandemic in 2021, coverage still rises yearly (figure 3). swedeamp coverage rate by hospitals thirty-six out of the 67 hospitals were included in the swedeamp database. two hospitals in the swedeamp register were reported as one hospital in the ipr database (table 5). the swedeamp register collected 5246 cases during the study period from 36 hospitals. on average, 24 patients went through lla per year and hospital (range = 0.2 – 112.7). however, six hospitals performed less than ten llas (26 llas in total). excluding these hospitals, the average yearly number will rise to 29 persons per year and hospital (n = 30 hospitals, 5220 patients, range = 2.0-112.7) (table 5). six hospitals reported over 90% of amputations: 1,817 out of 1,936 (93.9% coverage rate). four more hospitals reported between 80% to 89% of amputations: 769 out of 921 (83.5%). fourteen hospitals reported 40% 79% amputation: 2,159 out of 3,303 (65.1% coverage rate). in total, 24 hospitals obtained a coverage rate of ≥40% (table 5). suggestion on a benchmark of amputation levels we calculated the ratio using hospital reports to swedeamp with a coverage rate of more than 60% for one or more years (n = 36). the data includes a total of 4,419 amputations. with a suggested minimum coverage rate of ≥60%, the proposed benchmark ratios were ≤34.3% for transfemoral (tf) amputations, ≤8.4% for knee disarticulations (kd, where the knee joint is lost), and ≥55.3% for transtibial (tt) amputations. minimal ratio changes were observed when using coverage rates of 80% or 40% (table 6). discussion the swedeamp register covered 48.6% of all lower limb amputations (llas) performed during the study period, representing 17 out of 21 regions in sweden and 5,246 cases. the four non-participating regions were in northern sweden, three of which are the largest by area. while these regions have lower population densities, this alone does not fully explain their absence from the register. in total, eight regions either do not report to the register or have less than 20% coverage. data from 36 hospitals (53.7%) out of the 67 performing llas across the 21 regions were included in the registry between 2018 and 2023. this study's incidence report using the ipr database was lower than previous studies (17) as it only represents the tt, kd, and tf amputation levels. however, we also looked at the trend from 2008 to 2023 using the ipr database, and gladly, the incidence is declining, even after 2018.8 the reported data showed a notable trend of older patients being underrepresented. this may be due to the focus of healthcare professionals involved in the rehabilitation phase, who tend to concentrate on the outcomes of their patients rather than on those who are not enrolled in intensive rehabilitation program or who pass away shortly after surgery. figure 2: swedeamp coverage ratio by age groups (2018-2023). 20 30 40 50 60 70 80 90 0 .4 0 0 .4 5 0 .5 0 0 .5 5 0 .6 0 0 .6 5 0 .7 0 0 .7 5 swedeamp coverage ratio by age groups (2018 2023) age (groups) c o v e ra g e r a ti o age / ratio regression line ratio = 0.703 -0.0028 * age p (age) = 0.014 figure 3: swedeamp coverage ratio trends (2018–2023). 2018 2019 2020 2021 2022 2023 0 .0 0 .2 0 .4 0 .6 0 .8 1 .0 swedeamp coverage ratio by year (2018 2023) year c o v e ra g e r a ti o year / ratio regression line ratio = -52.215 + 0.0261 * age p (year) = 0.062 swedeamp coverage ratio trends (2018–2023). swedeamp coverage ratio by age groups (2018-2023) https://doi.org/10.33137/cpoj.v7i2.44089 8 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 interestingly, out of the 13 regions that reported more than 20% coverage rate, one region (östergötland) reported a 36.0% rate of kd amputations, while four regions reported between 12.1 % and 17.1%, and the remaining eight regions were all below 8.5% of all llas. a notable difference was found related to the ak/bk ratio, where two regions, västmanland (56.1%) and blekinge (52.8%), reported that more than half of all amputations were performed on the tf level. additionally, three more regions reported a higher ak/bk ratio (when the kd level is included), while seven regions reported a reverse ak/bk ratio. these regions have a substantial number of llas and high coverage, with median age and range similar to other regions with different ratios. no significant age-related differences were observed between the cohorts. these disparities warrant further exploration and may justify using amputation levels as a benchmark for comparison. however, there is an indication that patients not reported to swedeamp were from the oldest age group in the population. the question is not whether the 49% of missing data confounds the material represented in the swedeamp reports; it's more related to how much it affects. the effect can be addressed differently. we have demonstrated that although data is missing, the level of amputations in hospitals showed similar disparities when using 80% coverage compared with 40% coverage. the average of 29 initial amputations per year and hospital, ranging from 2.0 to 112.7 patients, is noteworthy. according to the ipr register, sixteen hospitals performed fewer than ten amputations over six years, including six in the swedeamp register. due to these low numbers, these hospitals were excluded from further statistical analysis. further investigation is needed to determine whether the volume of procedures at these hospitals impacts patient outcomes compared to hospitals that perform llas more frequently, or if this discrepancy could be due to incorrect registrations. these findings revealed the question of whether llas should be considered a specialized are of focus to improve the outcome in the future. the swedeamp initiative, based on hospitals’ voluntary participation, focuses on patient-centered care by tracking clinical outcomes, patient satisfaction, quality of life, and functional mobility. although no guidelines on lla in sweden are available, benchmarking against best practices or, as here, using the outcome data from swedeamp could help reduce variability and ensure that patients receive the most appropriate level of amputation. table 4: table 4: list of regions included in the coverage analysis (regions with at least 40% coverage in the swedeamp register are specified and included in the further analysis on amputation levels). region subjects in ipr database subjects in swedeamp database swedeamp coverage (%) included in analysis blekinge län 200 195 97.5 yes dalarnas län 322 181 56.2 yes gotlands län 97 81 83.5 yes gävleborgs län 302 177 58.6 yes hallands län 419 380 90.7 yes jämtlands län 165 0 0.0 no jönköpings län 454 294 64.8 yes kalmar län 242 47 19.4 no kronobergs län 171 68 39.8 yes norrbottens län 474 0 0.0 no skåne län 1,332 1,069 80.3 yes stockholms län 1,992 798 40.1 yes södermanlands län 325 64 19.7 no uppsala län 443 9 2.0 no värmlands län 271 16 5.9 no västerbottens län 275 0 0.0 no västernorrlands län 331 0 0.0 no västmanlands län 225 107 47.6 yes västra götalands län 1,947 1,135 58.3 yes örebro län 349 231 66.2 yes östergötlands län 452 394 87.2 yes sum 10,788 5,246 (5,110) * * data from swedeamp, covering ~40% of the ipr register across 13 swedish regions, included 5,110 registered amputations for analysis. https://doi.org/10.33137/cpoj.v7i2.44089 9 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 addressing these differences allows healthcare providers to provide more consistent and equitable treatment for patients undergoing lla nationwide. however, a key challenge for swedeamp, as highlighted in this study, is ensuring consistent data reporting from all healthcare providers. reporting gaps can hinder nationwide conclusions and obscure certain trends. table 5: list of hospitals performing llas and represented in both ipr and swedeamp data (n=36). hospital patients in ipr patients in swedeamp coverage rate (%) akademiska sjukhuset uppsala 441 9 2,0 blekingesjukhuset 200 195 97,5 capio s:t görans sjukhus 258 181 70,2 centrallasarettet växjö 143 68 47,6 centralsjukhuset karlstad 238 16 6,7 centralsjukhuset kristianstad 212 182 85,8 danderyds sjukhus 405 253 62,5 falu lasarett 234 181 77,4 hallands sjukhus* 419 380 90,7 helsingborgs lasarett 290 195 67,2 hudiksvalls sjukhus 101 2 2,0 hässleholms sjukhus 2 1 50,0 höglandsjukhuset eksjö 157 84 53,5 karolinska univ sjukhuset (huddinge + solna) 461 170 36,9 kungälvs sjukhus 32 12 37,5 lasarettet i motala 78 37 47,4 länssjukhuset ryhov jönköping 214 209 97,7 länssjukhuset i kalmar 157 34 21,7 mälarsjukhuset i eskilstuna 229 60 26,2 norrtälje sjukhus 107 9 8,4 nyköpings lasarett 93 4 4,3 sahlgrenska univ sjukhus (göteborg + mölndal) 704 525 74,6 sjukhuset i gävle 200 175 87,5 skånes univ.sjukhus (malmö + lund) 723 676 93,5 södersjukhuset 669 141 21,1 södertälje sjukhus 91 44 48,4 södra älvsborgs sjukhus borås 357 267 74,8 uddevalla näl 411 331 80,5 univ sjukhuset linköping 192 186 96,9 univ sjukhuset örebro 339 231 68,1 visby lasarett 97 81 83,5 vrinnevisjukhuset i norrköping 182 171 94,0 värnamo sjukhus 83 1 1,2 västerviks sjukhus 85 13 15,3 västmanlands sjukhus västerås 225 107 47,6 ystad lasarett 91 15 16,5 sum 8,920 5,246 * including two hospitals in the swedeamp register: halmstad and varberg. table 6: swedeamp amputations by level in all, 80%, 60%, and 40% hospital coverage rates. amputation level count in all ratio in all count in hospitals ratio in hospitals count in hospitals ratio in hospitals count in hospitals ratio in hospitals all hospitals (n = 36) >80% (n = 10) >60% (n = 17) >40% (n = 24) tf 1,828 34.9% 932 36.0% 1,603 36.3% 1,699 35.7% kd 438 8.4% 267 10.3% 373 8.4% 415 8.72% tt 2,980 56.8% 1,387 53.6% 2,443 55.3% 2,646 55.6% total 5,246 100% 2,586 100% 4,419 100% 4,760 100% https://doi.org/10.33137/cpoj.v7i2.44089 10 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 international comparisons of swedeamp data are primarily limited to scottish reports,14 as no other comparable registries exist. notable discrepancies arise when comparing the initial level of amputation between these registries. in scotland, 60% of amputations are tt, 1% are kd, and 39% are tf amputations,14 compared to 56.8%, 8.3%, and 34.9% in swedeamp, respectively. additionally, the average age of lla in scotland is 67 years, which is ten years younger than the average age in sweden.16 a deeper analysis of the patient characteristics and clinical decision-making processes in different geographic regions worldwide and within sweden could provide insights into the factors driving the current discrepancies. this might involve looking closer at age, gender, comorbidities, and the availability of limb-salvage interventions. swedeamp data has the potential to become a valuable resource for exploring how social determinants of health influence postamputation recovery and rehabilitation outcomes. benchmarking levels can be justified in several ways.26 in this study, we selected those hospitals with adequate registration coverage when comparing the ipr with swedeamp. another approach would be to choose the 'best' hospital, defined by high volume, a low ak/bk ratio, and low mortality rates for amputations, and use that as the benchmark. however, the same result would have been obtained since high-volume centers have similar ratios. a third approach involves selecting a 'perfect' candidate for amputation and benchmarking based on those cases. however, this approach is less realistic for llas due to age variations and the high comorbidity burden in this population. a potential limitation of this study is the discrepancy between the data provided by the administration managing the ipr register (swedish national board of health and welfare) and the online data from the same database, which showed a difference of 168 cases (1.6%). according to the data provider, this discrepancy may be due to instances where the same patient undergoes amputations at different hospitals, with each hospital independently registering the procedure. another limitation is the uncertainty regarding the impact of population ethnicity and regional comorbidity rates, both of which are known to influence outcomes following lla. additionally, outcomes can be affected by factors such as socioeconomic status, healthcare access, and genetic predispositions, which are not fully accounted for in the current swedeamp register.30 these findings highlighted the need for broader swedeamp participation to achieve comprehensive, reliable nationwide data on llas. expanded participation strengthens swedeamp's value as a research resource, allowing for deeper insights into procedural efficacy, regional disparities, and patient care improvements. this will ultimately promote higher standards in both local and national healthcare. conclusion the swedeamp register encompasses over half of all amputations documented in the ipr database. this study underscored the variations observed in both registries, particularly concerning lower limb amputations (llas) in terms of age, amputation levels, and geographic distribution. notable differences in the above-knee (ak) to below-knee (bk) amputation ratios were identified across various regions. additionally, our findings indicated inconsistencies in age group representation within the swedeamp data. based on the insights from the swedeamp data, we have proposed benchmark recommendations regarding amputation levels of ≤36.3% for tf, ≤8.4% for kd, and ≥55.3% for tt amputations. acknowledgements we would like to extend our sincere thanks to the steering group of swedeamp for granting us access to their data for analysis. declaration of conflicting interests anton g. johannesson is an employee of össur clinics, which provides services to prosthetic and orthotics clinics. reynir scheving, karolin lindgren westlund, and thor fridriksson are all employed by össur iceland ehf, medical office in reykjavik, iceland. authors contribution • anton g. johannesson: conceptualization; study oversight; data analysis; writing original; review and editing. • reynir scheving: conceptualization; study oversight; data analysis; review and editing. • karolin lindgren westlund: conceptualization; study oversight; review and editing. • thor fridriksson: conceptualization; study oversight; review and editing. all authors reviewed the manuscript and approved the final version. sources of support no external support was obtained for this project. references 1.national patient register [internet]. socialstyrelsen. 2023; [cited 2024, aug 15]. available from: https://www.socialstyrelsen.se/en/statistics-anddata/registers/national-patient-register/ 2.goodwin va, low msa, quinn tj, cockcroft ej, shepherd v, evans ph, et al. including older people in health and social care research: best practice recommendations based on the include framework. age ageing. 2023;52(6):afad082. doi: 10.1093/ageing /afad082 3.weiss rj, kärrholm j, rolfson o, hailer np. increased early mortality and morbidity after total hip arthroplasty in patients with socioeconomic disadvantage: a report from the swedish hip https://doi.org/10.33137/cpoj.v7i2.44089 https://www.socialstyrelsen.se/en/statistics-and-data/registers/national-patient-register/ https://www.socialstyrelsen.se/en/statistics-and-data/registers/national-patient-register/ 11 johannesson a.g, scheving r, westlund k.l, fridriksson t. evaluation of the swedeamp database: focus on coverage and amputation level rates. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.2. https://doi.org/10.33137/cpoj.v7i2.44089 canadian prosthetics & orthotics journal issn: 2561-987x evaluation of the swedeamp database johannesson et al., 2024 arthroplasty register. acta orthop. 2019;90(3):264–9. doi: 10.1080/17453674.2019.1598710 4.statistical database [internet]. statistics sweden. 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[cited 2024, aug 30]. available from: https://www.iso.org/committee/53630.html 28.population statistics [internet]. statistics sweden. [cited 2024, sep 2]. available from: https://www.scb.se/en/findingstatistics/statistics-by-subject-area/population/populationcomposition/population-statistics/ 29.kvb-ansökan för utlämnande av patientdata (kvb application for disclosure of patient data) [internet]. [cited 2024, aug 15]. available from: https://www.skane.se/om-regionskane/forskning/for-dig-som-forskar/personuppgifter-ochpatientdata/kvb-ansokan-for-utlamnande-av-patientdata/ 30.karam j, shepard a, rubinfeld i. predictors of operative mortality following major lower extremity amputations using the national surgical quality improvement program public use data. j vasc surg. 2013;58(5):1276–82. doi: 10.1016/j.jvs.2013.05.026 https://doi.org/10.33137/cpoj.v7i2.44089 https://www.statistikdatabasen.scb.se/pxweb/en/ssd/start__be__be0101/ https://www.statistikdatabasen.scb.se/pxweb/en/ssd/start__be__be0101/ https://www.socialstyrelsen.se/en/ https://kunskapsstyrningvard.se/kunskapsstyrningvard/kvalitetsregister.66155.html https://kunskapsstyrningvard.se/kunskapsstyrningvard/kvalitetsregister.66155.html https://sdb.socialstyrelsen.se/if_ope/val.aspx https://nhwstat.org/publications/ncsp-classification-surgical-procedures https://nhwstat.org/publications/ncsp-classification-surgical-procedures https://rcsyd.se/swedeamp/ https://rcsyd.se/swedeamp/publikationer/arsrapporter https://rcsyd.se/swedeamp/wp-content/uploads/sites/21/2024/05/arsrapport-swedeamp-2022.pdf https://rcsyd.se/swedeamp/wp-content/uploads/sites/21/2024/05/arsrapport-swedeamp-2022.pdf https://findingyourfeet.net/amputations/scottish-physiotherapy-amputee-research-group-sparg-report/ https://findingyourfeet.net/amputations/scottish-physiotherapy-amputee-research-group-sparg-report/ https://www.mayo.edu/research/labs/motion-analysis/research/limb-loss-preservation-registry https://www.mayo.edu/research/labs/motion-analysis/research/limb-loss-preservation-registry https://www.iso.org/committee/53630.html https://www.scb.se/en/finding-statistics/statistics-by-subject-area/population/population-composition/population-statistics/ https://www.scb.se/en/finding-statistics/statistics-by-subject-area/population/population-composition/population-statistics/ https://www.scb.se/en/finding-statistics/statistics-by-subject-area/population/population-composition/population-statistics/ https://www.skane.se/om-region-skane/forskning/for-dig-som-forskar/personuppgifter-och-patientdata/kvb-ansokan-for-utlamnande-av-patientdata/ https://www.skane.se/om-region-skane/forskning/for-dig-som-forskar/personuppgifter-och-patientdata/kvb-ansokan-for-utlamnande-av-patientdata/ https://www.skane.se/om-region-skane/forskning/for-dig-som-forskar/personuppgifter-och-patientdata/kvb-ansokan-for-utlamnande-av-patientdata/ all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives schneider n. evolving business models in orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.3. https://doi.org/10.33137/cpoj.v4i2.35876 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.35876 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 schneider n. evolving business models in orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.3. https://doi.org/10.33137/cpoj.v4i2.35876 stakeholder perspectives evolving business models in orthotics schneider n. * braceworks custom orthotics, 1-3500 24 ave nw, calgary, alberta, canada. introduction braceworks specializes in orthotic treatment for children with neuromuscular-skeletal disorders. the clinical practice of pediatric orthotics is informed by applied research and development (r&d). the clinic is located at the university of calgary in the hub of the local medical/research community enabling ease of collaboration with the schulich school of engineering and the alberta children’s hospital. in particular, braceworks is engaged in developing an objective and quantifiable approach to the assessment and treatment of chest wall deformities. the current research is focused on novel 3d imaging for chest wall anomalies: the early calgary experience.1 this builds on previous research including the calgary protocol for bracing pectus carinatum: a preliminary report2 and bracing of pectus carinatum: a quantitative analysis.3 braceworks’ specific contributions to the research include clinical knowledge, insight and experience, recruitment of study participants, data collection and analysis, and direct and indirect funding. aadl was established in 1980 to assist albertans with a long-term disability, chronic illness or terminal illness, in maintaining independence in their community through the provision of basic medical equipment and supplies to meet clinically assessed needs. sustainable access to orthotic care in alberta faces significant economic challenges. as presented at a meeting of the alberta association of orthotists and prosthetists (aaop) by dr. philip jacobs (may 17, 2001), these challenges include: a retail model of pricing of procedures that rewards prosthetics at the expense of orthotics, a shortage of skilled orthotists identified in the canadian p&o demographic study 2011,4 a labour market distorted by a public sector premium for prosthetic and orthotic technicians5 and clinicians,6 and a lack of success of orthotists to mature into a licensed profession regulated under the alberta health professions act.7 pricing of orthotic procedures in alberta the current aadl approved product lists – orthotics8 and prosthetics9 is loosely based upon the “cost accounting manual–a step-by-step guide to an effective cost accounting system for the orthotic and prosthetic facility” developed by the american orthotics and prosthetics association (aopa), with aaop making two significant open access volume 4, issue 2, article no.3. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract this submission provides an important historical context for understanding the current challenge facing the orthotic and prosthetic community in alberta including alberta aids to daily living (aadl), suppliers, and providers: maintaining sustainable access to orthotic care for people with mobility disorders in the face of declining real rates of reimbursement combined with increasing costs and a shortage of skilled clinicians. under the canada health act, the federal government delegates responsibility for providing health care to the provinces. this delegation of responsibility to the provinces results in a degree of variability of funding of orthotics and prosthetics between provinces across the country. funding of orthotics and prosthetics in alberta is characterized by structural inequities that favour prosthetics at the expense of orthotics. to the extent that the structural inequities that exist in alberta are related to governance by volunteer-run, non-profit organizations, they may be generalized to the canadian experience. finally, in a call to action a number of recommendations are made to address the challenge of sustainable access to orthotic care in alberta serving as a model for other provinces across canada. citation schneider n. evolving business models in orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.3. https://doi.org/10.33137/cpoj.v4i2.35876 keywords health economics, orthotics, business models, rehabilitation, alberta aids to daily living, funding * corresponding author nancy schneider, braceworks custom orthotics, 1-3500 24 ave nw, calgary, alberta, canada. e-mail: nancy@braceworks.ca orcid id: https://orcid.org/0000-0002-8441-4467 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.35876 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.35876 mailto:nancy@braceworks.ca https://orcid.org/0000-0002-8441-4467 2 schneider n. evolving business models in orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.3. https://doi.org/10.33137/cpoj.v4i2.35876 issn: 2561-987x evolving business models in orthotics schneider n., 2021 cpoj special s p e c ia l i s s u e modifications to the aopa cost accounting system upon implementation by aadl in 1991: 1.aaop discounted all the times to perform orthotic procedures in the aopa cost accounting system by 20%, as reported at an aaop meeting by mr. david moe (september 19, 2002). 2.aaop introduced a profit margin on material costs, and a profit margin that varied from component-tocomponent. the original aopa cost accounting system contains no profit margin on material costs. in 2001, aadl engaged dr. philip jacobs representing the institute of health economics of edmonton to review the aaop version of the “cost accounting system”. in his report, dr. jacobs concluded that the component-based formula was needlessly complex and contained some peculiar incentives related to markup on components. dr. jacobs proposed two new formulas intended to simplify the existing formula and remove the inequities that rewarded high component and low labour practices (i.e. prosthetics) at the expense of low component and high labour practices (i.e. orthotics). he proposed a service model based on times to perform procedures for orthotics and a retail model based on markup on components for prosthetics: price = direct materials + (rate x time) in response to dr. jacob’s research, aaop engaged framework partners inc. of calgary in october 2001 to review the aaop version of the cost accounting system and dr. jacob’s proposed formulas while undertaking a comprehensive survey to update the times to perform procedures. it took considerable effort for all 28 prosthetic and orthotic providers in alberta to fully appreciate the shortcomings of the aaop version of the aopa’s cost accounting system in terms of inequity between disciplines and between procedures within the same discipline. this understanding was achieved through an exhaustive demonstration comparing the cost of procedures under the current formula with the cost of procedures under dr. jacobs’ proposed formulas. the report by framework partners inc, presented to a meeting of aaop by mr. gord allen, mba, (september 19, 2002) validated dr. jacobs’ earlier conclusions and further reported that that this initial discount made has subsequently resulted in a differential in the effective hourly rate between prosthetics and orthotics that grew from 14.54% in 1991 to 39.75% in 2002. framework partners successfully surveyed twenty-seven out of a total of 28 facilities in alberta, for times to perform procedures for every procedure in the aadl approved product lists orthotics and prosthetics. the times to perform procedures were weighted based on the actual volume of procedures performed by each provider in the 2000-2001 aadl benefit year. working groups of clinicians in edmonton and calgary reviewed and verified the average weighted times to perform every procedure. the new aadl approved product lists orthotics and prosthetics were presented in compliance with global budget revenue neutrality for 2000-2001, as required by aadl who generously contributed valuable consumption data to the exercise. contrary to dr. jacobs’ recommendation for two separate formulas, and demonstrated in the framework report, aaop voted for a single, blended rate. separate rates for prosthetics and orthotics, within global budget neutrality, involve simply reallocating the mark up on components in orthotics to the labour rate for a service model of pricing for orthotics. blending the rate for prosthetics with the rate for orthotics retained the retail model of pricing. to the extent that the new retail oriented formula was based on thoroughly up-to-date times to perform procedures as of 2002, the formula implemented by aadl in 2003 represented an improvement over the previous retail model. while markups were not eliminated, they were corrected to at least narrow the differential in the effective hourly rate between prosthetics and orthotics: price = (direct materials x markup) + shipping + (rate x time) the markup on components has increased since 2003, exclusive of a constant factor for rework, loss and handling charges, maintaining the retail model of pricing and perpetuating the inequity for orthotics. given that all prosthetists and orthotists have the same educational qualifications and must meet the same national standards for certification set out by the orthotics prosthetics canada, orthotists deserve equal pay for work of equal value. governance of aaop in recognition of the findings of dr. jacob’s research later validated by framework, aadl has on more than one occasion offered to implement separate applications of the aopa cost accounting system for prosthetics (i.e. retail model of pricing based on markup on components) and orthotics (i.e. service model of pricing based on times to perform procedures). aaop has declined these offers. in order to understand aaop’s position with respect to maintaining a retail model for both disciplines, it may be helpful to review the bylaws of the aaop. according to its bylaws aaop is loosely constituted as a professional association representing individuals (i.e. clinicians, technicians and associates). it is not a trade association with any authority to represent businesses (i.e. aadl approved prosthetic and orthotic suppliers). since the https://doi.org/10.33137/cpoj.v4i2.35876 3 schneider n. evolving business models in orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.3. https://doi.org/10.33137/cpoj.v4i2.35876 issn: 2561-987x evolving business models in orthotics schneider n., 2021 cpoj special s p e c ia l i s s u e combined number of individual members of prosthetists, prosthetists-orthotists and related technicians and associates exceeds that of individual orthotists and related technicians and associates in aaop, the prosthetic issues tend to drive the agenda. hence, the outcome of the aaop’s vote in favour of a single, blended rate in 2003 may reflect a bias. the aging of the baby boom population is a very well established demographic trend. this trend has created increased demand for orthotic services while simultaneously decreasing the supply of orthotists available to deliver these services as they retire and are not sufficiently replenished. according to the demographic study conducted by the canadian association of prosthetists and orthotists in 2011, 60% of clinicians at that time were aged 45 and older and, planning to retire between 2021 and 2030.4 the majority of these clinicians represented small, owner-managed practices. despite various studies,4,10 identifying the looming shortage of orthotists institutional inertia has failed to address the increased demand for orthotists let alone met the other educational goal of graduate and post-graduate degrees to provide unbiased, peer-reviewed expertise. the economic impact of a lack of skilled orthotists creates challenges of succession planning for owner-managed practices to transition the knowledge, skills and experience required to maintain sustainable access to orthotic care. the net effect is that fewer and fewer older orthotists are focusing their practices on smaller and more specialized segments of the market. in particular, lower limb and spinal orthoses. the governance practices of aaop also appear to have limited orthotists in other ways. the alberta government offered to include prosthetists and orthotists under the health professions act in 1996,6 on the condition of licensure as the minimum standard in allied health. again, aaop declined the offer from the alberta government. prosthetists and orthotists remain unlicensed in alberta (and every other jurisdiction in canada). certification is limited to public education. licensure encompasses public education and extends beyond that to include public protection. licensure is a pre-requisite to applying for access to alberta netcare, a valuable tool providing fast, secure and confidential access to provincial electronic health records enabling communication between providers all along the patient’s continuum of care. merle taylor formula: public sector sets the standard for the private sector total compensation for clinicians and technicians employed in the public sector is significantly higher than their counterparts employed in the private sector. data for the public sector is derived directly from the collective agreements11 between the health sciences association of alberta (hsaa) and alberta health services (ahs). data for the private sector is based from occupations in alberta. total compensation for clinicians in the public sector is currently $136,666.76 which is $31,859.52 or 23.3% more than in private sector (table1). total compensation for technicians in the public sector is currently $113,442.16 which is $43,166.15 or 39.6% more than in the private sector (table 2). table 1: comparison of total compensation for clinicians in the public and private sectors. table 2: comparison of total compensation for technicians in the public and private sectors. in recognition of the public sector premium, the review of orthotist and prosthetics business arrangements by merle taylor management consultants commissioned by aadl recommended to a meeting of aaop (june 10, 2008) that: “annual increases to the labour rate should be tied to the public sector p&o labour rate increases.” aadl adopted the public sector as the standard for the private sector in 2008 based on total compensation for senior clinicians and technicians defined as step 9 under the collective agreement. equity with the public sector has been achieved only once, in 2012. since then, clinicians and technicians in the private sector have not received equal pay for work of equal value compared with their counterparts in the public sector. given that all prosthetists and orthotists employed in the private and public sectors are required to have the same educational qualifications and must meet the same national standards for certification as set out by the orthotics prosthetics canada, clinicians and technicians employed in the private and public sectors deserve equal pay for work of equal value. public sector private sector public sector premium salary hourly $44.75 $31.71 $13.04 29.0% annually $93,080.00 $65,961.34 $27,118.66 29.0% benefits mandatory $4,404.16 $4,314.67 $89,49 2.0% nonmandatory $15,958.00 n/a $15,958.00 100.0% total compensation $113,442.16 $70,276.01 $43,166.15 39.6% public sector private sector public sector premium salary hourly $54.46 $48.26 $6.20 11.4% annually $113,275.95 $100,378.99 $12,896.96 11.4% benefits mandatory $4,470.81 $4,428.25 $42.56 1.0% nonmandatory $18,920.00 n/a $18,920.00 100.0% total compensation $136,666.76 $104,807.24 $31,859.52 23.3% https://doi.org/10.33137/cpoj.v4i2.35876 4 schneider n. evolving business models in orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.3. https://doi.org/10.33137/cpoj.v4i2.35876 issn: 2561-987x evolving business models in orthotics schneider n., 2021 cpoj special s p e c ia l i s s u e call to action prosthetics and orthotics in alberta is characterized by longstanding inequities between disciplines and, between public and private sectors. these inequities have had a serious negative impact on sustainable access to orthotic care for albertans with chronic conditions. the inequity between orthotics and prosthetics is structural. it was imbedded into aaop’s version of the aopa cost accounting methodology in 1991 when aaop discounted times to perform orthotic procedures by 20% and added a novel markup on components. this retail model of pricing has benefited prosthetics at the expense of orthotics for 20 years. despite aadl offers to maintain the existing retail model for prosthetics while creating a separate service model for orthotics, as recommended by independent researchers, aaop has maintained the status quo. the inequity between the public and private sectors is the direct result of the public sector premium in alberta, currently 23.3% for clinicians and 39.6% for technicians, and, aadl’s failure to implement and maintain the merle taylor formula correctly based on total compensation in the public sector. sustainable access to orthotic care for albertans depends on aadl, as the policy maker, working together with prosthetic and orthotic suppliers, to demonstrate their leadership to resolve these inequities. it is recommended that aadl build on their previous research by dr. philip jacobs, independently validated by framework partners inc., to: 1.engage a qualified consultant to implement and maintain a service model of pricing for orthotic procedures based on times to perform procedures according to the merle taylor formula including: a) the rate must be based on total compensation in the public sector derived directly from the collective agreement between the hsaa and ahs. b) a rigorous pricing review adjustment process including manufacturers suggested retail price provided directly by suppliers as the standard for pricing of components. consistent sourcing of cost data direct from suppliers will enable aadl to align prosthetics and orthotics with current practices in other benefit areas. 2.resolve the shortage of skilled orthotists by amending aadl policy op-05: specialty assessors for prosthetic and orthotic benefits to recognize foreign trained graduates of the international prosthetics and orthotics society’s (ispo) category one programs as eligible to practice in alberta. in the medium to longer-term, explore opportunities to address the educational void by developing a graduate program in collaboration with post-secondary institutions in alberta with programs in kinesiology, biomedical engineering, physical medicine and rehabilitation, rehabilitation engineering and assistive technologies. 3.bring prosthetics and orthotics into alignment with the standard of allied health professions under the health professions act to enable them access to electronic health records under alberta netcare. 4.improve the efficiency and productivity of orthotists by reducing paper burden. replace the cumbersome authorizations and claims process for services to existing devices with an adjustment to the cost of the device to include the cost of support and service of the device, particularly for clients aged 18 and under. acknowledgements with thanks to kim van gelderen, data analyst, for her contribution to calculating the total compensation and current public sector premiums for clinicians and technicians in alberta. declaration of conflicting interests as a key member, aadl agreements teams (2000 – 2013) including chair, aaop steering committee – study of formula and fee schedule (2000–2003), nancy has developed in-depth knowledge and experience with the economics of pricing of orthotics and prosthetics in alberta including the granular data and pricing models. she has made a significant contribution to ensuring sustainable access to prosthetic and orthotic care for albertans with disabilities. she successfully initiated the transition from a retail to a professional services model of pricing for orthotics, created generic codes to dramatically simplify fee schedules, and effectively changed the landscape to attract investment in biomechanical sciences and engineering research required to advance clinical practice. sources of support braceworks benefits from federal and provincial support under biotalent canada, mitacs and irap to provide opportunities for young undergraduate and graduate students in biomedical engineering from the university of calgary, university of waterloo, university of british columbia and simon fraser university to contribute to advancing the calgary protocol. references 1.lam jyk, ronsky j, schneider m, brindle m, lopushinsky s, schneider n, et al. novel 3d imaging for chest wall anomalies: the early calgary experience. canadian association of paediatric surgeons, caps annual meeting, banff ab october 2017. 2.kravarusic d, dicken bj, dewar r, harder j, poncet p, schneider m, et al. the calgary protocol for bracing of pectus carinatum: a preliminary report. j pediatr surg. 2006;41(5):923-6. doi: 10.1016/j.jpedsurg.2006.01.058 3.bugajski t, murari k, lopushinsky s, schneider m, ronsky j. bracing of pectus carinatum: a quantitative analysis, j pediatr surg. 2018;53(5):1014-1019. doi: 10.1016/j.jpedsurg.2018.02.034 https://doi.org/10.33137/cpoj.v4i2.35876 5 schneider n. evolving business models in orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.3. https://doi.org/10.33137/cpoj.v4i2.35876 issn: 2561-987x evolving business models in orthotics schneider n., 2021 cpoj special s p e c ia l i s s u e 4.blocka d, tomorrow’s forecast: 2011 demographic study on the p&o profession in canada, alignment, 2018 5.occupations in alberta, prosthetic and orthotic technicians [internet]. [cited 2021 july 25]. available from: https://alis.alberta.ca/occinfo/occupations-in-alberta/occupationprofiles/prosthetic-and-orthotic-technician/ 6.occupations in alberta, prosthetic and orthotic clinicians [internet]. [cited 2021 july 25]. available from: https://alis.alberta.ca/occinfo/occupations-in-alberta/occupationprofiles/prosthetist-and-orthotist/ 7.alberta health professions act [internet]. alberta queen’s printer. 2021; [cited 2021 july 25]. available from: https://www.qp.alberta.ca/1266.cfm?page=h07.cfm&leg_type=act s&isbncln=9780779823130 8.aadl approved product list – orthotic benefits, effective april 1, 2019 [internet]. [cited 2021 july 25]. available from: https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-80452498f464c2e3/resource/63abb711-7fcd-4119-aecc9d23362034c7/download/aadl-manual-o-products-2019-04.pdf 9.aadl approved product list – prosthetic benefits, effective april 1, 2019 [internet]. [cited 2021 july 25]. available from: https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-80452498f464c2e3/resource/ac69cc5f-ed58-4a41-ae911629b080e05c/download/aadl-manual-p-products-2019-04.pdf 10.raschke, s. the future of prosthetics & orthotics as a profession: the greatest threat is . . . ? [internet]. the o&p edge. 2002; [cited 2021 july 25]. available from: https://opedge.com/articles/viewarticle/2002-08-01/2002-08_21 11.health science association of alberta, collective agreements [internet]. [cited 2021 july 25]. available from: https://hsaa.ca/about-us/collective-agreements/ author scientific biography braceworks is distinguished by expertise in pediatric clinical practice supported by full-time, professional management and product planning. nancy schneider bcom, co-founder and ceo since 1996 is the operational manager leading a high performance team delivering capacity utilization rates that consistently exceed the industry standards while successfully diversifying into product development through applied research. https://doi.org/10.33137/cpoj.v4i2.35876 https://alis.alberta.ca/occinfo/occupations-in-alberta/occupation-profiles/prosthetic-and-orthotic-technician/ https://alis.alberta.ca/occinfo/occupations-in-alberta/occupation-profiles/prosthetic-and-orthotic-technician/ https://alis.alberta.ca/occinfo/occupations-in-alberta/occupation-profiles/prosthetist-and-orthotist/ https://alis.alberta.ca/occinfo/occupations-in-alberta/occupation-profiles/prosthetist-and-orthotist/ https://www.qp.alberta.ca/1266.cfm?page=h07.cfm&leg_type=acts&isbncln=9780779823130 https://www.qp.alberta.ca/1266.cfm?page=h07.cfm&leg_type=acts&isbncln=9780779823130 https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/63abb711-7fcd-4119-aecc-9d23362034c7/download/aadl-manual-o-products-2019-04.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/63abb711-7fcd-4119-aecc-9d23362034c7/download/aadl-manual-o-products-2019-04.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/63abb711-7fcd-4119-aecc-9d23362034c7/download/aadl-manual-o-products-2019-04.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/ac69cc5f-ed58-4a41-ae91-1629b080e05c/download/aadl-manual-p-products-2019-04.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/ac69cc5f-ed58-4a41-ae91-1629b080e05c/download/aadl-manual-p-products-2019-04.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/ac69cc5f-ed58-4a41-ae91-1629b080e05c/download/aadl-manual-p-products-2019-04.pdf https://opedge.com/articles/viewarticle/2002-08-01/2002-08_21 https://hsaa.ca/about-us/collective-agreements/ brunelli s, sancesario a, iosa m, delussu a.s, gentileschi n, bonanni c, foti c, traballesi m. which is the best way to perform the physiological cost index in active individuals with unilateral trans-tibial amputation? canadian prosthetics & orthotics journal.2019;volume2, issue1, no.5. https://doi.org/10.33137/cpoj.v2i1.32953 issn: 2561-987x volume 2, issue 1 2019 (online) r e s e a r c h a r t i c l e all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian prosthetics & orthotics journal (cpoj) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). https://doi.org/10.33137/cpoj.v2i1.32953 http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation 1 open access physiological cost index in individuals with trans-tibial amputation volume 2, issue 1, article no.5, december 2019 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index research article which is the best way to perform the physiological cost index in active individuals with unilateral trans-tibial amputation? brunelli s1*, sancesario a2, iosa m1, delussu a.s1, gentileschi n2, bonanni c2, foti c2, traballesi m1 1 fondazione santa lucia, scientific institute for research, hospitalization and health care, rome, italy. 2 physical and rehabilitation medicine, tor vergata university of rome, rome, italy. introduction lower-limb amputees represent a particular group of interest in terms of gait, like previous studies have highlighted, as these persons use more energy compared to the healthy ones.1-4 moreover, the energy cost and the effort required has been shown to be related to the level and the cause of the amputation: the higher the amputation level the greater the walking energy cost;1,5,6 further vascular disease amputees have higher walking energy expenditure than traumatic amputees.7,8 oxygen consumption measurement (vo2) with a portable metabolimeter is the primary choice for assessing energy cost of walking (ecw) in amputees and it has been widely used in literature.5,9 however, it is time-consuming, the instrumentation needed is expensive and the methodology requires trained personnel. vo2 is the amount of oxygen taken up and utilized by the body mass per minute (ml/kg/min). ecw is the oxygen cost of walking and is defined as oxygen consumption related to walking speed: vo2 (ml/kg/min)/walking speed (m/min).10 abstract background: physiological cost index (pci) is a simple method used to estimate energy expenditure during walking. it is based on a ratio between heart rate and self-selected walking speed. previous studies reported that pci is reliable in individuals with lower limb amputation but only if there is an important walking impairment. no previous studies have investigated the correlation of pci with the energy cost walking (ecw) in active individuals with traumatic unilateral trans-tibial amputation, considering that this particular category of amputees has an ecw quite similar to healthy individual without lower limb amputation. moreover, it is important to determine if pci is also correlated to ecw in the treadmill test so as to have an alternative to over-ground test. objectives: the aim of this study was to evaluate the correlation between pci and ecw in active individuals with traumatic trans-tibial amputation in different walking conditions. the secondary aim was to evaluate if this correlation permits to determine ecw from pci values. methodology: ninety traumatic amputees were enrolled. metabolic data, heart rate and walking speed for the calculation of ecw and for pci were computed over-ground and on a treadmill with 0% and 12% slopes during a 6-minute walking test. findings: there is a significant correlation between ecw and pci walking over-ground (p=0.003; r2=0.10) and on treadmill with 12% slopes (p=0.001; r2=0.11) but there is only a poor to moderate correlation around the trendline. no significant correlation was found walking on treadmill with 0% slope. the bland-altman plot analysis suggests that is not possible to evaluate ecw directly from pci. conclusions: pci is a reliable alternative measure of energy expenditure during walking in active individuals with trans-tibial amputation when performing over-ground or at high intensity effort on treadmill. pci is therefore useful only for monitoring a within subject assessment. citation brunelli s, sancesario a, iosa m, delussu a.s, gentileschi n, bonanni c, foti c, traballesi m. which is the best way to perform the physiological cost index in active individuals with unilateral trans-tibial amputation? canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.5.https://doi.org/10.33137/cpoj. v2i1.32953. keywords oxygen consumption, prosthesis, gait, treadmill, lower limb amputation, physiological cost index, energy cost of walking, walking test. *corresponding author dr. stefano brunelli, fondazione santa lucia, irccs, via ardeatina 306, 00179 rome, italy. orcid: https://orcid.org/0000-0002-5986-1564 tel. +39 0651501844; fax +39 0651501919 e-mail: s.brunelli@hsantalucia.it doi: https://doi.org/10.33137/cpoj.v2i1.32953 article info received: august 4, 2019 accepted: december 12, 2019 published: december 14, 2019 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v2i1.32953 https://doi.org/10.33137/cpoj.v2i1.32953 https://orcid.org/0000-0002-5986-1564 mailto:s.brunelli@hsantalucia.it https://doi.org/10.33137/cpoj.v2i1.32953 brunelli s, sancesario a, iosa m, delussu a.s, gentileschi n, bonanni c, foti c, traballesi m. which is the best way to perform the physiological cost index in active individuals with unilateral trans-tibial amputation? canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.5. https://doi.org/10.33137/cpoj.v2i1.32953 2 cpoj brunelli et al. 2019 physiological cost index in individuals with trans-tibial amputation physiological cost index (pci) considers heart rate as an indicator of energy expenditure. macgregor has studied how pci reflects the heart function and therefore indirectly the o2 consumption.11the pci is a valuable tool, that provides a simple, quick and inexpensive method to evaluate the o2 consumption during exercise12,13 and it is based on the linear relationship between vo2 and heart rate at submaximal workloads.11 pci has been used as an outcome measure in many pathologies 14-17 and in elderly persons.18 in literature, several authors have used the pci as an outcome measure to evaluate the energy expenditure of walking in lower limb amputees.1-4,19-22 hagberg et al. have reported the test-retest reproducibility of the pci between lower limb amputees and healthy persons, however there is no evidence of a linear correlation between pci and ecw when performing high intensity effort.3 chin et al. observed a significant correlation between pci and oxygen uptake in trans-femoral amputees, however, the study was conducted on a small group of 6 unilateral trans-femoral amputees.23 about the correlation between pci and ecw, graham et al. reported that pci scores did not correlate with vo2, indicating that the pci is not a valid measure of energy expenditure in healthy persons. walking at a comfortable pace for healthy persons provides only a minimal stress on the cardiovascular system and very low energy expenditure very near to resting values.24 besides macgregor indicated that pci requires a submaximal effort.11 considering that there should be a positive correlation between pci and ecw only in the condition with a significant walking impairment, we hypothesize that active individuals with trans-tibial amputation (tta) without any stump problems or clinical comorbidities were quite similar to healthy persons and therefore pci could not be effective in the standard testing condition, i.e. during over-ground walking. in effect, ecw values in active tta have shown small differences compared to those of healthy persons.25,26 finally, pci has been always calculated when the participants were walking over-ground: the large track needed for testing is not practical in all clinical setting and the presence of too many turns may influence the walking speed and consequently the pci. a treadmill evaluation of pci could be easier, especially for laboratories with small spaces. no previous studies have investigated the correlation between pci and ecw on active adult traumatic tta. the primary aim of this study was to evaluate the reliability of pci, compared to ecw, in this particular category of individuals during over-ground walking test (owt), treadmill walking test with 0%. slope (twt0%), and treadmill walking test with 12% slopes (twt12%). this last test was performed with the hypothesis that when increasing the cardiopulmonary requests, there would be a stronger correlation between the two measures. the secondary aim was to evaluate if it is possible to determine ecw from pci values of owt. methodology study design: cross-sectional study setting: research laboratory of amputees section of operative unit 4, fondazione santa lucia, rehabilitation hospital, rome. sample: the study sample included tta. they were randomly selected from those who met the inclusion criteria in our database. inclusion criteria: 1) unilateral traumatic tta, 2) age 2065 years old, 3) mass < 116 kg, 4) use of the prosthesis for at least 18 months and for a minimum of 4 hours per day, 5) a mobility level of k3 or more based on the klevels27 (i.e. amputees that have the ability for ambulation with variable cadence, typical of community ambulatory or active adults), 6) absence of pathological stump condition that may affect prosthesis use, 7) absence of mental disorder, 8) absence of heart disease (except for hypertension well controlled by drugs) or respiratory disease 9) no usage of drugs that interferes with heart rate (i.e. beta-blockers, digoxin), 10) the rehabilitative program and the prosthetic training were completed, 11) absence of pain or mobility deficit on sound limb. all participants gave their informed consent and they received no payment. all tta were fitted with a modular prosthesis with total surface bearing socket, passive vacuum suspension system and a dynamic-response foot. the tta performed a 6-minute walking test (6mwt) in three different conditions: one over-ground and two on a treadmill. the owt was carried out in a 61-meter hallway with straight course and regular surface, walking back and forth at comfortable self-selected walking speed (ssws).26 on the treadmill (runrace, technogym, italy) the twt0% and the twt12%, were conducted with the speed indicator covered; each participant chose his ssws without knowing the speed indicated on the treadmill.26 the walking tests were performed in the morning in three different days in a random sequence. during all 6mwts cardiac and metabolic data were collected with a portable gas analyzer k4b2 (cosmed, italy), that allowed a breath by breath recording of vo2 and heart rate. the time length of the 6mwt was enough for the tta to reach the steady state phase of cardiac and metabolic data. before each tests the tta sat quietly for 10 minutes in order to collect rest heart rate data, for calculation of pci. the data obtained at self-selected walking speed were used to calculate ecw and pci. the mean walking speed of the owt was calculated as the ratio of distance to time in the steady state phase only. for the measurement of pci and ecw, some precautions were taken: before the tests, enrolled tta had to abstain from exhausting efforts, fatty foods, smoking and alcohol (the day before) and in the previous 60 minutes they were denied to take any kind of stimulants (tea, coffee, chocolate) or smoking. the pci and ecw data of each patient during the three walking conditions were calculated. the ecw was calculated using the formula “oxygen consumption/speed”. the formula used for pci calculation was “walking heart rate – resting heart rate /speed”. https://doi.org/10.33137/cpoj.v2i1.32953 brunelli s, sancesario a, iosa m, delussu a.s, gentileschi n, bonanni c, foti c, traballesi m. which is the best way to perform the physiological cost index in active individuals with unilateral trans-tibial amputation? canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.5. https://doi.org/10.33137/cpoj.v2i1.32953 3 cpoj brunelli et al. 2019 physiological cost index in individuals with trans-tibial amputation statistical analysis pearson’s correlation coefficient (r) was computed to assess the association between the values of ecw and pci data of each condition. the correlations between ecw and pci between trials and participants within the same condition were computed. the possible agreement between pci and vo2 was analyzed by means of blandaltman plot. the alpha-level of statistical significance was set at 0.05 for all the analysis. spss 17.0 software (spss, inc., chicago, il) was used for all the statistical analysis. results we evaluated 90 male participants whose characteristics are summarized in table 1. none of the participants interrupted the test sessions due to fatigue. table 1: demographic characteristics of the sample. the mean values of owt were: ecw=0.195±0.039 ml/kg/m and pci=0.380±0.183 (beats/m), p=0.003. (figure 1). the chart shows that there is a positive correlation between the two parameters. the large interparticipant variation means that there is only a poor to moderate correlation around the trendline. figure 1: correlation between pci and ecw during over-ground walking test, (p=0.003). the mean values of twt0% were ecw=0.307±0.084 ml/kg/m and pci=0.465±0.205 (beats/m), p=0.075 (figure 2). last, in the third condition (twt+12%) mean ecw was 0.525±0.132ml/kg/m, mean pci was 0.977±0.355 (beats/m), p=0.001 (figure 3). the chart shows that there is a positive correlation between the two parameters but there is only a poor to moderate correlation around the trendline. figure 4 shows, by means of the bland-altman plot, how the differences between pci and vo2, evaluated for overground walking, vary with respect to their mean value. figure 2: correlation between pci and ecw during treadmill walking test with 0% slope, (p=0.075). figure 3: correlation between pci and ecw during treadmill walking test with 12% slope, (p=0.001). figure 4: bland-altman plot of pci and vo2 for over-ground walking. discussion pci is easy to calculate, is low-cost and no high technology equipment is required, but in order to start using it in trials as an alternative measure of ecw, it’s important to know their correlation and limits. this is the first study that compared ecw and pci in a large sample of individuals with lower limb amputation. the primary aim of this study was to evaluate the correlation between pci and ecw in active traumatic tta. our results showed that there is not a statistically significant correlation between ecw and pci during the twt0% (p=0.075) while there is a significant correlation 90 male trans-tibial amputees age (y) weight (kg) height (m) time since amputation (months) klevel mean 46.3 86.3 1.7 114.5 3.6 sd 9.7 13.5 0.7 86.1 0.5 https://doi.org/10.33137/cpoj.v2i1.32953 brunelli s, sancesario a, iosa m, delussu a.s, gentileschi n, bonanni c, foti c, traballesi m. which is the best way to perform the physiological cost index in active individuals with unilateral trans-tibial amputation? canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.5. https://doi.org/10.33137/cpoj.v2i1.32953 4 cpoj brunelli et al. 2019 physiological cost index in individuals with trans-tibial amputation between ecw and pci during the owt (p=0.003). this may be explained by the traballesi et al. findings where the authors reported that the over-ground test is the one that better reflects real walking with prostheses.5 moreover, the same study demonstrated that amputees tested on treadmill have shown a significantly slower ssws. the absence of correlation between pci and ecw on treadmill with a slope of 0% might depend on a decrease of physiological expenditure as participants are walking slower. when the treadmill test was performed with higher intensity effort (twt+12%), the correlation between ecw and pci is statistically significant (p=0.001). the effort of walking with 12% inclination causes an increase of the heart rate. we can speculate that, on treadmill, the more intense the exercise, the higher the correlation between ecw and pci. previous studies which examined the correlation between pci and vo2 in healthy persons without gait impairment did not report any correlations.3,24 compared with those studies, that investigated the pci in healthy persons, we obtain a mean over-ground pci value of 0.38, which is close but higher to hagberg (pci mean value=0.33) and graham (pci mean value=0.32). these pci values are much lower in patients with great walking impairment such as spinal cord injury patients walking using a gait orthosis (pci=1.97),28 or patients with stabilized hemiparesis (pci=0.76),29 or trans-femoral amputees (pci=0.55).2 pci reproducibility in healthy individuals and lower limb amputees has been reported, but there is lack of evidence about its correlation with ecw.2 pci is directly proportional to heart rate and inversely proportional to speed, so any situation influencing heart rate or speed could influence pci. healthy persons have a lower increase of working heart rate than persons with gait impairments because the cardiovascular stress is much lower.24 so studies that investigated pci on healthy participants could not be indicative for participants with gait impairment. in our study we assessed only tta whose amputation was due to traumatic injuries. this is because dysvascular amputees usually have comorbidities that could influence the general health of the patients and their heart rate. the tta of our study have yet gait difficulties with respect to the healthy population, but they do not have other comorbidities. in this way we could evaluate the correlation between pci and ecw having only the gait impairment as a difference between individuals with trans-tibial amputation and healthy participants. we can confirm our hypothesis that tta without any other comorbidities are quite similar to healthy persons, so it is important to change the pci treadmill testing condition towards a submaximal exercise to reach a significant correlation of pci with ecw for clinical or evaluation purpose. ultimately the bland-altman plot shows two biases that do not allow to evaluate ecw directly from pci. firstly, the fact that the mean value of the difference between pci and vo2 is different from zero revealed the presence of an absolute systematic difference between the two parameters. then, the linear relationship clearly shows that the increment of this difference is proportional to the mean. these two biases support the idea of a relationship, but not an agreement, between pci and ecw. study limitations in our study we have analyzed only traumatic transtibial amputees so these results should not be generalized to larger populations with amputation or to other persons with gait impairments due to other reasons. the participants were allowed to walk at different ssws over the three different conditions which will invariably affect the energy cost of walking and the correlations between the parameters. the amputees, in fact, walk slower on the treadmill to reduce their metabolic energy expenditure. we did not select the over-ground sswt for the treadmill speed because we have followed the methods of traballesi’s paper in which the amputees chose their ssws without knowing the speed indicated on the treadmill.26 further studies should test pci and ecw with other treadmill inclination in order to find the equation, if it exists, that permits to calculate the ecw from pci data. moreover, further studies are needed to confirm the suggestion that pci has a higher correlation with the ecw when the walking effort increase. conclusion our data allow us to state that pci value do not permit to calculate ecw. anyway the pci can be used as an alternative measure of energy expenditure in active individuals with trans-tibial amputation for a within participant assessment only when recorded during overground walking or on treadmill with 12% slope. in reverse, the pci does not correlate with ecw when recorded during treadmill walking with 0% slope. these findings have to be considered when pci is used as a tool for estimate energy expenditure of walking. acknowledgements thanks to livia brunelli, durham university, uk, for the english language editing. declaration of conflicting interests the authors have no conflicts of interest to declare. sources of support no funding for this study was provided. ethical approval the study approval was obtained by local ethics committee. author contribution • stefano brunelli conceived the idea of the work, supported the data analysis and led the writing of the manuscript. • andrea sancesareo drafted the manuscript, managed the data files, interpretation of the data. • marco iosa conducted the statistical analyses, interpretation of the data. https://doi.org/10.33137/cpoj.v2i1.32953 brunelli s, sancesario a, iosa m, delussu a.s, gentileschi n, bonanni c, foti c, traballesi m. which is the best way to perform the physiological cost index in active individuals with unilateral trans-tibial amputation? canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.5. https://doi.org/10.33137/cpoj.v2i1.32953 5 cpoj brunelli et al. 2019 physiological cost index in individuals with trans-tibial amputation • anna sofia delussu acquisition, analysis of the data. • noemi gentileschi supported the writing of the manuscript. • cinzia bonanni supported the writing of the manuscript. • calogero foti revised the manuscript critically for important intellectual content. • marco traballesi revised the manuscript critically for important intellectual content, design of the work. references 1. visser mccarthy i, marks l, davis rc. is hip muscle strength the key to walking as a bilateral amputee, whatever the level of the amputations? prosthet orthot int. 2011;35(4):451-8. doi:10.1177/0309364611422268 2. hagberg k, häggström e, brånemark r. physiological cost index (pci) and walking performance in individuals with transfemoral prostheses compared to healthy controls. disabil rehabil. 2007;29:643-649. doi: 10.1080/09638280600902869 3. hagberg k, tranberg r, zügner r, danielsson a. reproducibility of the physiological cost index among individuals with a lower-limb amputation and healthy adults. physioter res int. 2010;16(2):92-100. doi: 10.1002/pri.477 4. wright da, marks l, payne rc. a comparative study of the physiological costs of walking in ten bilateral amputees. prosthet orthot int. 2008;32(1):57-67. doi: 10.1080/03093640701669108 5. traballesi m, porcacchia p, averna t, brunelli s. energy cost of walking measurements in subjects with lower limb amputations: a comparison study between floor and treadmill test. gait posture. 2008;27(1):70-5. doi:10.1016/j.gaitpost.2007.01.006 6. delussu as, brunelli s, paradisi f, iosa m, pellegrini r, zenardi d. et al. assessment of the effects of carbon fiber and bionic foot during overground and treadmill walking in transtibial amputees. gait posture, 2013;38(4),876-882. doi:10.1016/j.gaitpost.2013.04.009 7. waters rl, perry j, antonelli d, hislop h. energy cost of walking of amputees: the influence of level of amputation. j bone joint surg am. 1976;58(1):42-6. 8. gailey rs, wenger ma, raya m, kirk n, erbs k, et al. energy expenditure of transtibial amputees during ambulation at self-selected pace. prosthet orthot int. 1994;18(2):84-91. doi:10.3109/03093649409164389 9. traballesi m, delussu as, averna t, pellegrini r, paradisi f, brunelli s. energy cost of walking in transfemoral amputees: comparison between marlo anatomical socket and ischial containment socket. gait posture. 2011;34(2):270-274. doi:10.1016/j.gaitpost. 2011.05.012 10. schwartz mh, koop se, bourke jl, & baker r. a nondimensional normalization scheme for oxygen utilization data. gait posture. 2006;24(1):14-22. doi:10.1016/j.gaitpost.2005.06.014 11. macgregor j. the objective measurement of physical performance with long term ambulatory physiological surveillance equipment (lapse). in proceedings of 3rd international symposium on ambulatory monitoring, 1979. academic press. 12. macgregor j. the evaluations of patient performance using long term ambulatory monitoring technique in the domiciliary environment. physiotherapy 1981;67:30-3. 13. åstrand, p. o., rodahl, k., dahl, h. a., & strømme, s. b. textbook of work physiology: physiological bases of exercise. 4th ed. champaign il: human kinetics;2003 14. leung ak, wong af, wong ec, hutchins sw. the physiological cost index of walking with an isocentric reciprocating gait orthosis among patients with t(12)-l(1) spinal cord injury. prosthet orthot int. 2009;33(1):61-8. doi: 10.1080/03093640802562368. 15. plasschaert f, jones k, forward m. the effect of simulating weight gain on the energy cost of walking in unimpaired children and children with cerebral palsy. arch phys med rehabil. 2008;89(12):2302-8. doi: 10.1016/j.apmr.2008.05.023 16. steven mm, capell ha, sturrock rd, macgregor j. the physiological cost of gait (pcg): a new technique for evaluating nonsteroidal anti-inflammatory drugs in rheumatoid arthritis. br j rheumatol. 1983;22:141-5. doi:10.1093/rheumatology/22.3.141 17. olney sj, nymark j, brouwer b, culham e, day a, heard j, et al. a randomized controlled trial of supervised versus unsupervised exercise programs for ambulatory stroke survivors. stroke. 2006;37:476-81. doi:10.1161/ 01.str.0000199061.85897.b7 18. peebles kc, woodman aldridge ad, skinner ma. the physiological cost index in elderly subjects during treadmill and floorwalking. n z j physiother. 2003;31:116. 19. malek f, somerson js, mitchel s, williams rp. does limb-salvage surgery offer patients better quality of life and functional capacity than amputation? clin orthop relat res. 2012;470(7):2000-6. doi:10.1007/s11999012-2271-1 20. chin t, maeda y, sawamura s, oyabu h, nagakura y, takase i, machida k. successful prosthetic fitting of elderly trans-femoral amputees with intelligent prosthesis (ip): a clinical pilot study. prosthet orthot int. 2007;31(3):271-6. doi:10.1080/03093640601040152 21. andrysek j, klejman s, torres-moreno r, heim w, steinnagel b, glasford s. mobility function of a prosthetic knee joint with an automatic stance phase lock. prosthet orthot int. 2011;35(2):163-70. doi:10.1177/0309364 611408495 22. rau b, bonvin f, de bie r. short-term effect of physiotherapy rehabilitation on functional performance of lower limb amputees. prosthet orthot int. 2007;31(3):25870. doi:10.1080/03093640600994615 https://doi.org/10.33137/cpoj.v2i1.32953 brunelli s, sancesario a, iosa m, delussu a.s, gentileschi n, bonanni c, foti c, traballesi m. which is the best way to perform the physiological cost index in active individuals with unilateral trans-tibial amputation? canadian prosthetics & orthotics journal. 2019; volume2, issue1, no.5. https://doi.org/10.33137/cpoj.v2i1.32953 6 cpoj brunelli et al. 2019 physiological cost index in individuals with trans-tibial amputation 23. chin t, sawamura s, fujita h, nakajima s, ojima i, oyabu h, et al. the efficacy of physiological cost index (pci) measurement of a subject walking with an intelligent prosthesis. prosthet orthot int. 1999;23:45-9. doi:10.3109/03093649909071609 24. graham rc, smith nm, white cm. the reliability and validity of the physiological cost index in healthy subjects while walking on 2 different tracks. arch phys med rehabil 2005;86:2041-6. doi:10.1016/j.apmr.2005.04.022 25. jarvis hl, bennett an, twiste m, phillip rd, etherington j, & baker r. temporal spatial and metabolic measures of walking in highly functional individuals with lower limb amputations. arch phys med rehab. 2017;98(7):1389-99. doi:10.1016/j.apmr.2016.09.134 26. brunelli s, delussu as, paradisi f, pellegrini r, traballesi m. a comparison between the suction suspension system and the hypobaric iceross seal-in x5 in transtibial amputees. prosthet orthot int. 2013;37(6):436-44. doi:10.1177/0309364613476531 27. functional levels lower extremity prostheses (klevels) – region b medicare supplier bulletin. dmepos bulletin 95–01, january 1995. 28. arazpour m, bani ma, hutchins sw, jones rk. the physiological cost index of walking with mechanical and powered gait orthosis in patients with spinal cord injury. spinal cord. 2013;51(5):356-9. doi:10.1038/sc.2012.162 29. danielsson a, willén c, sunnerhagen ks. measurement of energy cost by the physiological cost index in walking after stroke. arch phys med rehabil. 2007;88(10):1298-303. doi:10.1016/j.apmr.2007.06.760 https://doi.org/10.33137/cpoj.v2i1.32953 volume 6, issue 2 2023 articles in this special issue has been invited and reviewed by dr. silvia ursula raschke and dr. hossein gholizadeh. d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e v o l u t i o n i n p r o s t h e t i c s & o r t h o t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x https://jps.library.utoronto.ca/index.php/cpoj/editorinchief 1 erenstone j. 3d printed prostheses: the path from hype to reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.4. https://doi.org/10.33137/cpoj.v6i2.42141 stakeholder perspectives 3d printed prostheses: the path from hype to reality erenstone j* mountain orthotic and prosthetics services, lake placid, ny usa. introduction the field of prosthetics has undergone a remarkable transformation in recent years, with 3d printing technology emerging as an innovation that promises to revolutionize the design and production of prosthetic devices. this paper explores the history of the use of 3d printing and how popular perceptions influenced the development and application of the technology. the observations and perspectives in this paper are based on the author's firsthand experience integrating the technology into clinical practice, as well as experience founding multiple related organizations and companies. an advisory firm named gartner developed a graphical representation called the “hype cycle” which tracks the adoption and maturity of emerging technologies and concepts within industries like 3d printing, also known as adaptive manufacturing. the hype cycle consists of five phases: innovation trigger, peak of inflated expectations, trough of disillusionment, slope of enlightenment, and the plateau of productivity.1 3d printing and 3d printed prosthetics have followed the phases of the hype cycle and this framework provides a helpful guide to understand their recent histories. with an understanding of the perceptions and mis-perceptions that were created, the o&p field is in a better position to understand how to effectively use the technology in the future. history before discussing the hype cycle and how it relates to the popularity of 3d printed prostheses, we need to acknowledge that 3d printing was around long before it was popular. technology used in printing can be traced to a 1951 patent which used projected light to harden a photosensitive colloid.2 then, in 1981 japanese inventor hideo kodama created a device that used ultraviolet lights to harden polymers to create solid objects. in 1984 charles “chuck” hull altered the concept and used kodama's uv lamps to cure photosensitive resin layer-by-layer to create a part. this technology was labeled stereolithography. from this additive technology other deposition processes were developed, including ones that are used today. these are broadly defined by iso/astm 52900:2021 into seven categories: 1) binder jetting; 2) directed energy deposition; 3) material extrusion; 4) material jetting; 5) powder bed fusion; 6) sheet lamination; and (7) vat photopolymerization.3 in the field of prosthetics, 3d printing has been used for more than 30 years. in 1992, a researcher at northwestern university named josh rolock developed a technology to open access abstract 3d printing has an over forty-year history but has only become popular in the last fifteen years with the expiration of restrictive patents which allowed open access and unfettered innovation by a broad range of technology developers. during the last decade interest in prostheses made by 3d printing has grown in popularity. the interest in devices has followed the gartner hype cycle as 3d printing companies and associated organizations have used popular claims about 3d printed prostheses to increase their own company’s popularity. these claims created unrealistic expectations which outran the early-stage limitations of the technology, causing disillusion. currently, the industry is moving beyond these limitations and the field seems to be advancing at a sustainable rate. this article provides an understanding of the history of popular misconceptions surrounding the technology. it provides a basis for separating the myth from reality in 3d printing technology so the reader can question the popular preconceived ideas and find the real value. with a greater understanding of the past, one can apply lessons to present technology use and guide the direction of future 3d printing. this paper will also discuss lessons applicable to both high and low-income countries along with providing recommendations for the future development. citation erenstone j. 3d printed prostheses: the path from hype to reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.4. https://doi.org/10.33137/cpoj.v 6i2.42141 keywords orthotics, prosthetics, 3d printing, additive manufacturing, digital workflow, rehabilitation * corresponding author: jeffrey erenstone, cpo mountain o & p services, 7 old military road, lake placid, ny usa. e-mail: erenstone@gmail.com orcid id: https://orcid.org/0000-0003-1015-9616 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.4, 2023 special issue https://doi.org/10.33137/cpoj.v6i2.42141 https://doi.org/10.33137/cpoj.v6i2.42141 https://doi.org/10.33137/cpoj.v6i2.42141 https://orcid.org/0000-0003-1015-9616 https://jps.library.utoronto.ca/index.php/cpoj/index 2 erenstone j. 3d printed prostheses: the path from hype to reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.4. https://doi.org/10.33137/cpoj.v6i2.42141 canadian prosthetics & orthotics journal issn: 2561-987x 3d printed prostheses: the path from hype to reality erenstone j, 2023 (special issue) fabricate sockets named squirt-shape as part of his phd research.4 rolock continued to develop this technology throughout the 1990s. this early additive technology allowed the one-step fabrication of prosthetic sockets and functions in a similar way to the most popular 3d printed socket fabrication used today. mass popularity even though the history of 3d printing spans several decades, its mass popularity didn’t grow until 2009, when the now famous stratasys' patent expired. suddenly it became possible for a company to produce and sell simple material extrusion printers (commonly known as fdm printers) without infringement of stratasys' intellectual property. soon after this expiration, an open-source project called reprap acted as a technology trigger when numerous people started to use the designs to develop their own low-cost printers.5 some of the more functional designs were used to found companies which sold these low-cost printers. the expectations of this technology increased exponentially as people made objects with their printers and posted about them on social media for others to appreciate. some companies, like makerbot, launched large marketing campaigns which drew the attention of mass media. they started to compare the adoption of 3d printers to adoption of pc computers and promoted their goal of having a printer in every household.6 3d printed prosthesis entered the media streams in december 2012 with the publishing of the “the first 3d printed prosthetic hand for a child” made by ivan owen. his project was promoted in makerbot’s marketing material including the campaign for the opening of its second retail store. this “feel good” humanitarian story offered a counter story to the troubling media reports of 3d printed guns and became a popular human-interest story which was published broadly in the media and served as a triggering event for its popularity.7 during this time an online community named “e-nable”, which was founded by jon schull, promoted designs and messages that anyone with a low cost printer could download the designs, print prosthetic hands, and help children in need.8 in reality, the vast majority of devices were used only for a short time and have been found not satisfactory for a user's daily functional tasks and activities.9 over the next couple of years, the popularity of 3d printed prostheses (in tandem with 3d printers in general) grew into the “peak of inflated expectation” on the hype cycle. this peak of public attention corresponded to high stock prices of companies like stratasys10 and 3d systems.11 stratsys reached its all-time high on january 03, 2014 at a price of $136.4612 and 3d systems peaked on the same day at $96.42.13 afterward their stock prices dropped quickly and have yet to return in value. my personal history with 3d printing started in 2010 by utilizing printed parts in designing adaptive sport orthotic and prosthetic devices. the technology was very advantageous in prototyping and fabricating small quantity sport components. printing greatly improved fabrication time compared to conventional methods. in september of 2014, a youtube video was published by an e-nable member titled “a $50 3d-printed prosthesis compared to a $42,000 myoelectric prosthesis.”14 this dramatic and inaccurate comparison measured the cost of the raw materials for a 3d printed hand to the full cost of a myoelectric arm billed to an insurance carrier in the priceregulated us healthcare system. it created a lot of hype in the media and enshrined the trope that “3d printed hands cost $50.” tropes with similar dollar amounts are repeated to this day and cause misperception of the cost involved in prosthetic care. in response to the inaccuracies, i reached out to schull with my concerns. the e-nable founder thanked me for reaching out, mentioned that no other prosthetist had contacted him yet, and asked me to post my thoughts on the e-nable google community which led to regular engagement within the community over the next couple years. through this time period, i worked to educate the wellmeaning volunteers about complexities of prosthetic care while learning about 3d printing technology and its potential. the exchange of ideas was rewarding, but also frustrating to see that the tropes and misperceptions persisted due to the loose organizational structure of the online community. in this time period many 3d printing companies started to struggle through the “trough of disillusionment” as people realized that the low-cost 3d printers of that time were finicky to use and regularly produced inferior products when compared to conventional fabrication methods. everyone agreed that tremendous potential existed in 3d printing, but it seemed the technology was too early in its development to be viable for most applications. through engagement with these companies, i was able to identify some applications in the prosthetic field which were advantageous for my own clinical practice, including designing and fabricating diagnostic sockets, flexible inner sockets, and cosmetic covers. the successes found in the clinic inspired the founding of a 3d printing company named create o&p15 which has since been acquired by pva med. the company was in step with the rest of the 3d printing field at that time which seemed to be on the “slope of enlightenment.” for this technology to be adopted and effective, it needed to be supplied as a complete end to end solution which included scanning, cad software, printer, application knowledge, and support. a complete system, based around the creation of prosthetic devices with a proven clinical application, the prosthetic field was willing to embrace the technology and incorporate it into clinical care. while this comprehensive approach did not scale quickly, in the right hands, over time, it started to meet some of the expectations that were promised at the peak of the hype. https://doi.org/10.33137/cpoj.v6i2.42141 3 erenstone j. 3d printed prostheses: the path from hype to reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.4. https://doi.org/10.33137/cpoj.v6i2.42141 canadian prosthetics & orthotics journal issn: 2561-987x 3d printed prostheses: the path from hype to reality erenstone j, 2023 (special issue) 3d printing is a popular term while additive manufacturing (am) is a more technological term used by established researchers, engineers and industrialists. am technology is not likely to allow anyone with a 3d printer to provide “amazingly low-cost prosthetic care” that was promised. the need for trained clinicians remains. however, now that this technology is in the hands of professionals who understand the complexity and challenges of clinical prosthetic care, the technology is on the slow and steady path to productivity and will have a firm place in the future of o&p care. every o&p provider should be introduced to the technology and have a basic understanding of how-to 3d scan and digitally design devices in cad. this foundation of knowledge will help them incorporate the technology into their daily practice. at this point, there are numerous people in the o&p field who are utilizing am regularly, but it is not yet the majority. greater adoption requires companies to develop robust end to end workflows which provide a complete road map from initial patient encounter to the completion of a deliverable definitive device. the companies that provide this comprehensive workflow will have an enduring presence in the market and facilitate more regular use of am by practitioners in their practices. this is the path that leads to popular use of the technology and achieves the “plateau of productivity,” as identified in the hype cycle. lessons learned a few years ago, i was in the mindset that i could completely give up modifying (rectifying) patient models made from plaster and only work in the digital space going forward. being familiar with several types of cad software and having experience with a wide range of am, my typical workflow consisted of making prototypes (diagnostic devices) on low cost fdm printers in my own facility and then forwarding these designs to central fabrication (am service bureaus) with expensive powder bed fusion printers for definitive devices. it was exciting to be done with plaster and never wash white dots off my shoes again. however, when discussing these plans with colleagues, it was pointed out that a dogmatic approach to only using digital technology was going to be less efficient and limiting in the care that could be provided. most o&p fabrication technologies have been used in the field for decades. numerous tools and strategies have been developed around these methods and the bugs have already been worked out of the process. it doesn’t make sense to give up on comfortable processes and ignore the wealth of knowledge and experience acquired over decades. these days, every time i start a project, i ask myself, which parts are best done using digital technology and which parts are better done using traditional methods. more often than not, a hybrid approach which uses a combination of digital technology and traditional methods is the right answer. for example, i regularly use scanning, cad, and am to make a thin-walled socket which prints quickly, then reinforce the outer surface of this socket with a conventional carbon fiber or fiberglass lamination to add strength and conventional alignment componentry. this mindset has carried over to my work in low-income countries and my work with an organization named operation namaste.16 the organization has done most of its work in nepal where there are several well outfitted prosthetic fabrication facilities for patients who have means to travel. in these cases, there is no need to introduce new digital technology that is still in early stage development and not fully vetted. meanwhile, there are people in nepal who still struggle to travel to urban areas with established clinics. for these cases operation namaste is developing a compact mobile lab which utilizes digital technology. a computer and 3d printer are much smaller and easier to transport than a plaster lab, an oven and vacuum forming system. our mobile lab, which we call “limbkit,” includes all the equipment needed to fabricate transtibial prosthesis and can be packaged into a case that is transportable by suv. in this system we are using a low-cost fdm 3d printer to make clear thinned-wall diagnostic sockets out of petg, fitting them as a diagnostic socket to confirm the fit, then adding a prescribed amount of fiberglass reinforcement to strengthen them into definitive devices. the kit doesn’t require a plaster lab because operation namaste has developed its own web-based cad software named “collaborative cad”. in the future, when this system is fully developed it will allow prosthetists to fit devices in numerous low resource settings and conflict zones where care wasn’t previously available. we are not trying to disrupt established functional clinical care, but instead, look to extend care into areas with unmet needs. any time a new technology can allow practitioners to provide care where they have not been able to previously, the technology is much more likely to be adopted. operation namaste is working to extend current care into geographical regions where care was previously lacking. meanwhile other am developers are forging the pathway into new types of clinical care elsewhere where the technology was not previously available. call to action for additive manufacturing to reach its potential in the field of prosthetics, am developers need to keep in mind the temperament of the practitioners using the technology. they need to develop more end-to-end workflows which fabricate orthotic and prosthetic devices that are difficult or impossible to make by traditional fabrication methods. when practitioners see that they will be able to reliably provide better care, the majority will embrace new digital technologies and be willing to shift away from the traditional methods that they are currently comfortable with. https://doi.org/10.33137/cpoj.v6i2.42141 4 erenstone j. 3d printed prostheses: the path from hype to reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.4. https://doi.org/10.33137/cpoj.v6i2.42141 canadian prosthetics & orthotics journal issn: 2561-987x 3d printed prostheses: the path from hype to reality erenstone j, 2023 (special issue) additionally, when it comes to designing and fabricating structural components there are engineering limitations that need to be overcome or properly taken into account. there needs to be an increase in consistent isotropic bonding of material in am devices so the properties are consistent with the properties found in other manufacturing processes such as vacuum forming or cnc milling. this is especially a concern in fdm printed sockets where the chopped layer in the vertical (z direction) and rapid cooling glass transition level between the layers makes the z direction significantly weaker than the x and y directions and causes reduced strength of the part in this orientation.17 the lack of consistent bonding in all directions makes designing new innovative load bearing components difficult because the material dynamics are not predictable and hard to model. powder bed fusion printers (more commonly known as sls or mjf printers) use methods that are more isotopic than fdm, but improvements are needed in fabrication consistency and part-to-part quality control with these processes as well. furthermore, regarding prosthetic sockets, there is a substantial knowledge gap surrounding standardized methods for the mechanical testing. this absence of standardized test methods means the structural properties of these sockets are not clearly defined or understood. this causes difficulty for new socket technology to be designed because designers don’t know the strength requirements necessary in their design. in other words, even if am parts become isotropic and consistent, the socket innovators do not have enough guidance to fully understand strength requirements to incorporate into their new designs. to begin addressing this dilemma, in 2020 a multidisciplinary group of professionals was assembled by the aopa and has published a white paper called “mechanical testing of transtibial prosthetic sockets: a discussion paper from the american orthotic and prosthetic association socket guidance workgroup.” this group aims to inspire researchers to narrow the gaps of knowledge required to make measurable standards for socket strength.18 with these types of improvements, additive manufacturing and other digital technology have the ability to achieve their potential and likely displace the current traditional methods. with a good understanding of the necessary requirements, am can be on the path to achieving the improvement necessary to convince the majority of the practitioners in the field to use it routinely. in the meantime, it is clear that am has a place in our field today and this place will grow every year. however, the field should not abandon the currently successful, traditional methods until am progresses further. instead, we should take a hybrid approach of using 3d printing (am) for some aspects of fabrication and traditional methods for the rest. acknowledgements none. declaration of conflicting interests the author is the founder of the charity operation namaste https://www.operationnamaste.org/ and the owner of mountain orthotic and prosthetic services in lake placid, usa. sources of support none. references 1.tserpes. gartner hype cycle [internet]. wikimedia foundation. 2005; [cited 2023 aug 22]. available from: https://en.m.wikipedia.org/wiki/gartner_hype_cycle 2.pollard d. 3d printing where did it all start? prescouter custom intelligence from a global network of experts [internet]. 2019; [cited 2023 aug 23]. available from: https://www.prescouter.com/2017/03/3d-printing-start/ 3.iso/astm 52900:2021(en), additive manufacturing? general principles [internet]. 2021; [cited 2023 aug 20]. available from: https://www.iso.org/obp/ui/#!iso:std:74514:en 4.rovick js. direct, automated fabrication of sockets for artificial limbs. northwestern university; 1993. 5.the official history of the reprap project [internet]. 2021; 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[cited 2023 nov 8]. available from: https://www.3dsystems.com/ 14.simon j. a $50 3d-printed prosthesis compared to a $42,000 myoelectric prosthesis (3d universe) [internet]. youtube. 2014; [cited 2023 aug 28]. available from: https://www.youtube.com/watch?v=chpumcshklu https://doi.org/10.33137/cpoj.v6i2.42141 https://www.operationnamaste.org/ https://en.m.wikipedia.org/wiki/gartner_hype_cycle https://www.prescouter.com/2017/03/3d-printing-start/ https://www.iso.org/obp/ui/#!iso:std:74514:en https://all3dp.com/history-of-the-reprap-project/ https://all3dp.com/history-of-the-reprap-project/ https://www.wired.com/2012/09/how-makerbots-replicator2-will-launch-era-of-desktop-manufacturing/ https://www.wired.com/2012/09/how-makerbots-replicator2-will-launch-era-of-desktop-manufacturing/ https://www.imdb.com/title/tt3557464/ https://enablingthefuture.org/about/ https://www.macrotrends.net/stocks/charts/ssys/stratasys/stock-price-history https://www.macrotrends.net/stocks/charts/ssys/stratasys/stock-price-history https://www.macrotrends.net/stocks/charts/ddd/3d-systems/stock-price-history https://www.macrotrends.net/stocks/charts/ddd/3d-systems/stock-price-history https://www.stratasys.com/en/ https://www.3dsystems.com/ https://www.youtube.com/watch?v=chpumcshklu 5 erenstone j. 3d printed prostheses: the path from hype to reality. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.4. https://doi.org/10.33137/cpoj.v6i2.42141 canadian prosthetics & orthotics journal issn: 2561-987x 3d printed prostheses: the path from hype to reality erenstone j, 2023 (special issue) 15.ready to transform your practice? [internet]. pvamed. 2022; [cited 2023 nov 8]. available from: https://www.pvamed.net/ 16. technology, tools & training to serve amputees in need [internet]. operation namaste: united states. [cited 2023 nov 8]. available from: https://www.operationnamaste.org/ 17.zohdi n, yang r (chunhui). material anisotropy in additively manufactured polymers and polymer composites: a review. polymers. 2021;13(19):3368. doi:10.3390/polym13193368 18.gariboldi f, cutti ag, fatone s, nickel e, dickinson a, steer j, et al. mechanical testing of transtibial prosthetic sockets: a discussion paper from the american orthotic and prosthetic association socket guidance workgroup. prosthet orthot int. 2023;47(1):3–12. doi:10.1097/pxr.0000000000000222. author scientific biography jeffrey erenstone has b.s. in biology from the university of new hampshire and two post-bachelor certificates in prosthetic and orthotic practitioners from newington and century colleges. he has been a certified prosthetist and orthotist (cpo) for nearly 20 years. he has owned his clinical practice named mountain orthotic and prosthetics services for 16 years which is in northern new york. he serves as the chair of the american orthotic and prosthetic association (aopa) digital o&p committee and socket guidance workgroup. he is the founder and president of the non-profit known as operation namaste. jeff has devoted years to improving prosthetic care around the world, especially in lmics. he is a well-known innovator of digital technology for prosthetic care and is working on systems of making silicone prosthetic liners in lmics and a mobile prosthetic lab called the limbkit. https://doi.org/10.33137/cpoj.v6i2.42141 https://www.pvamed.net/ https://www.operationnamaste.org/ all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 2 2022 letter to the editor pardy c, scott s, barnert j, reimer c. letter to the editor regarding: evolving business models in orthotics by schneider n. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.5. https://doi.org/10.33137/cpoj.v5i2.38313 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i2.38313 1 pardy c, scott s, barnert j, reimer c. letter to the editor regarding: evolving business models in orthotics by schneider n. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.5. https://doi.org/10.33137/cpoj.v5i2.38313 letter to the editor letter to the editor regarding: evolving business models in orthotics by schneider, n. pardy c1*, scott s2, barnert j2, reimer c3 1 alberta orthotic and prosthetic centre, calgary, ab, canada. 2 cascade prosthetic services, calgary, ab, canada. 3 colman prosthetics and orthotics, calgary, ab, canada. abstract the purpose of this letter is to continue the dialogue regarding the paper "evolving business models in orthotics" in the canadian prosthetics & orthotics journal volume 4, issue2, no.3, 2021. in it we present the perspective of the current alberta association of orthotists and prosthetists (aaop) and provide additional context and information on historical events. finally, we provide additional clarity on how costing is approached in the province of alberta (canada) and the purported inequity in compensation between the two disciplines. dear canadian prosthetics & orthotics journal editorial board, this response is on behalf of the alberta association of orthotists and prosthetists (aaop). the aaop is a voluntary non-profit professional organization that promotes communication and awareness in all matters pertaining to our profession. within that framework, our role is to promote the professional services of our members within alberta who provide orthotic and prosthetic treatments which enrich the lives of those we help. this role includes being a collective voice in discussion with various organizations with respect to matters of pricing and policy. we are not a governing body and do not set pricing on our own accord. we have a recommended pricing structure, though no individual clinic is required to adhere to it. the purpose of this letter is to comment on events and actions attributed to our association contained within the recent cpoj article “evolving business models in orthotics by schneider, n.”1 and provide accurate contextual information and insight into the pricing of orthotic and prosthetic treatment in alberta in general, and how it is applied by alberta aids to daily living program specifically. we hope this will help to expand the discussions that are presently occurring across the country with respect to national and provincial pricing guides. to begin with, this article1 states that it provides a broad perspective of the orthotic business model and improvements that would have a positive impact on patient care and orthotic compensation. while that is a notable and welcome endeavour, in our opinion, we find the focus strays from that objective preferring to concentrate on grievances with the aaop and a perceived discrepancy between prosthetic and orthotic compensation. it must be noted that this article1 focuses on pricing as it pertains to the alberta aids to daily living program (aadl) even though, they are one of many organizations that provide funding for orthotic and prosthetic care and treatment to albertans with mobility impairment. orthotists and prosthetists in alberta are not licensed by the province and membership in the aaop is voluntary and has no authority to dictate pricing or pricing models. current aadl policy states that pricing is to be established through a “mutually agreeable” process, and in the past, aadl has worked with the aaop to establish pricing. that is no longer the case as aadl sets its pricing with minimal consultation from the vendor representatives. each clinic has the freedom to establish its own pricing methodology for care and treatment of clientele who do not meet aadl eligibility criteria. the overarching argument of this article appears to be that the governance of aaop has limited orthotists and fostered a long-standing structural inequity between orthotic and prosthetic treatment. further, that this perceived inequity is reflected in the aadl’s approved products lists (apl’s) for orthotics and prosthetics,2,3 and favours prosthetics at the expense of orthotics. this document will address and provide documentation supporting the position we will put forth. the article1 lays out many points open access * corresponding author: connor pardy, m.sc., cpo alberta orthotic and prosthetic centre, calgary, ab, canada. past-president of the alberta association of orthotists and prosthetists email: connor@aopconline.com orcid id: https://orcid.org/0000-0003-4475-9775 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 5, issue 2, article no 5. 2022 https://doi.org/10.33137/cpoj.v5i2.38313 http://www.albertaoandp.com/ http://www.albertaoandp.com/ mailto:connor@aopconline.com https://orcid.org/0000-0003-4475-9775 https://jps.library.utoronto.ca/index.php/cpoj/index 2 pardy c, scott s, barnert j, reimer c. letter to the editor regarding: evolving business models in orthotics by schneider n. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.5. https://doi.org/10.33137/cpoj.v5i2.38313 canadian prosthetics & orthotics journal issn: 2561-987x letter to the editor pardy et al., 2022 purporting to substantiate their argument, we would like to add additional information and provide a more accurate picture of orthotic and prosthetic pricing in alberta in 2021. the underpinnings of the article’s inequity argument appear to stem from the following issues. pricing of orthotic procedures in alberta the article1 stated that the current aadl’s approved product lists are loosely based upon the american orthotic prosthetic association’s (aopa) cost accounting manual,4 this is not entirely accurate. prior to 2001 this was the case, however, since 2002 they have been based loosely on a formula developed by dr. phillip jacobs in 2001, though there are some similar points in common with the aaop cost accounting system.5 from 2002 through to 2017, aadl pricing has been based on the following formula, price = direct materials (materials + 12% handling/loss/rework/warranty) + shipping + (rate x time) this is substantially more closely aligned with the initial formula presented by dr. jacobs, price = direct materials + (rate x time) than it is with the aopa cost accounting method. this method is still in use for pricing most of the orthotic and prosthetic care however, aadl abandoned it for some of the procedures and new benefit codes introduced in 2017. it is important to note that handling/loss/rework/ warranty “markup” has not increased since 2003 but, in fact, decreased from 16% to 12% with the implementation of the “merle taylor” report 6 of 2008. this markup does not vary from component to component as the paper1 suggests but is applied equally across components and disciplines. times to perform orthotic procedures the perceived inequity if procedure times stems from an alleged 1991 aaop decision to discount the times to perform orthotic procedures in the aopa cost accounting system by 20%. no citation was provided for this claim other than a statement that this was reported by an aaop member at an aaop meeting on september 19, 2002, 11 years after that event. a search of the aaop archives have revealed no discount occurred; personal communications with the individual specifically named, indicated that he has no recollection of making that statement, though he does recall the meeting.7 further, discussions with orthotist members who were practicing and active with the aaop at the time have no recollection of this. however, they did indicate that the aadl, on their own initiative, did reduce the times of some knee bracing procedures and there is some debate as to whether that has been rectified with the current pricing methodology. there exists some evidence that this occurred but was limited in scope of application and appears to have been addressed in 2001 and 2002.7 additionally, a scan of the times to perform orthotic procedures in alberta and those of other jurisdiction that also used the aopa cost accounting manual, as well as the merle taylor report that reviewed selected times to perform procedures from ontario and manitoba show no evidence of any serious discrepancy in this area (alberta professions and occupations bureau letter, charlton d to guest d, august 08, 1991; ref: hdb.31/8974-1). the standard mantra of documentation is that “if it is not written it did not happen”, in this case no written documentation is presented or can be found; therefore, one can only conclude that this did not happen. aaop introduced a profit margin on material costs the article1 asserts that in 1991 the aaop introduced a profit margin on material costs that varied from component to component, and that the original aopa cost accounting system contained no such profit margin. a review of the aopa cost accounting manual indicates that a “loss and rework” factor are added to the material and component costs prior to arriving at a “total cost of direct materials ”. this varied from component to component based on risk of loss and formed the material cost entry on the calculations worksheet.4 it was this practice, consistent with the aopa cost accounting system that was added into aaop calculations and is not a margin of profit. governance of aaop the article1 refers, though provides no citations, to three studies being instrumental in the development of pricing formulae: the study by dr. jacobs, the frameworks survey, and the merle taylor report. both dr. jacobs study and the merle taylor report were funded by aadl, while the frameworks study was funded by the aaop. the frameworks study did not validate dr. jacob’s work, as it dealt with times to perform procedures and not compensation or labour rates. after a thorough review the aaop determined frameworks contained some serious flaws and was never accepted by the aaop and was not officially given to aadl and played no role in the pricing discussions. ultimately, the aaop committee decided that an enhanced version of the dr. jacobs formula would become the go forward pricing formula presented by the aaop to the aadl in april 2003.7 there are no documents to support the argument that aadl has “offered” to implement separate applications of the aopa cost accounting system. aadl consistently used the “merle taylor” formula from 2008 until 2017, when this was arbitrability changed by aadl without aaop input. in 2007, a proposal was put forth to aadl to implement a pilot project creating a ”service” model of pricing for orthotics.8 this was never implemented. while the membership of the aaop has fluctuated through the years the split between orthotic and prosthetic members has always been fairly even. at present aaop has 35 members: 12-prosthetists, https://doi.org/10.33137/cpoj.v5i2.38313 3 pardy c, scott s, barnert j, reimer c. letter to the editor regarding: evolving business models in orthotics by schneider n. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.5. https://doi.org/10.33137/cpoj.v5i2.38313 canadian prosthetics & orthotics journal issn: 2561-987x letter to the editor pardy et al., 2022 11-orthotists, 6-dually certified, 2-associates (who are both from solely orthotic facilities), 2-registered prosthetic technicians, and 2-registered orthotic technicians. it is not reasonable to assume that the dual certifees are partial to prosthetic issues over orthotic issues, nor is it reasonable to state that “prosthetic issues tend to drive the agenda”. the article1 postulates that the governance practices of the aaop limits orthotists. one example cited is inclusion in the health professions act of 1996 and making the condition of licensure the minimum standard in allied health. many factors work against licensure for this profession in alberta and across the country and the aaop has not been the only provincial association to attempt to achieve this goal. issues that exist today were also present in 1996 and no provincial association has managed to attain licensure, however, in alberta it has not been for lack of effort or acceptance of a government offer. in 1991, the aaop approached the health disciplines board making a presentation on our profession. we were advised by the registrar that the act did not restrict the right to practice and only restricts the use of titles (alberta professions and occupations bureau letter, charlton d to guest d, august 08, 1991. ref: hdb.31/8974-1). at that time, subsequent the decision in the matter of canadian board for certification of prosthetists and orthotists v. canadian pharmaceutical association and board for orthotists certification, titles were protected by trademark, and it appears the overriding opinion was this would have been costly and laborious for little to no gain. this matter was brought to the fore front by the aaop, and the same individual who spearheaded the initiative in 1991, sought a legal opinion on this again in 2001. it was the opinion of the association’s lawyer (according to a letter by renouf s to guest d in september 27, 2001) at the time that success would have been unlikely. this was not simply a matter of the aaop “declining” an offer. the merle taylor formula in response to an impasse in discussions, and a rejection of the pilot project for two different pricing methods for orthotics and prosthetics, the aaop and aadl mutually agreed to a 3rd party review of orthotic and prosthetic business arrangements in alberta. aadl contracted, and paid, merle taylor consulting to carry out this review. the objectives being to determine: • whether aadl’s current payment arrangements and fee schedule for orthotic and prosthetic services are adequate compared to similar services and • whether there are different payment approaches that would improve the efficiency and fairness of the payment process. the result was a process that removed the aspect of profit from materials and componentry and created a formula for developing a charge-out rate (should never have been called a labour rate) that was equitable, though not equal, between orthotics and prosthetics. this formula takes into account public sector salaries for both clinicians and technicians, administrative time, inflation, billable/nonbillable hours, benefits, weighted labour times (prosthetic more clinician time vs orthotics more technician time), overhead, and a profit objective. in short, all the costs of operating a prosthetic and orthotic facility are captured in this rate, as a result, the rates differ between orthotics and prosthetics but are equitable. the labour component of this formula was based on the “top-of-range” from the public facilities for both clinicians and technicians as derived from the health sciences association of alberta collective agreements and applied equally to both the orthotic and prosthetic calculations. they were not, however, based on “total compensation” as asserted in the paper.1 in 2008, the merle taylor report determined that for facilities to realize a potential profit of 10% charge-out rates of $162.00/hr for prosthetics and $130.00/hr for orthotics was required. while the final numbers were different, these results were similar to internal reviews taken in 2002 that identified differing rates for orthotics and prosthetics. while this was equitable, it was not equal. it was put forward that given orthotists and prosthetists have the same qualifications and must meet the same national standards, the practice of blending the rates to create a single chargeout rate would continue. this reduced the prosthetic rate and profit potential and increased the orthotic rate and profit potential. in 2010, aadl offered to discuss the separation of rates, while two attendees at the table agreed, the aaop was unanimous keeping the same single charge out rate. the blending of the rates continues today, the current aadl charge-out rate that was established in 2019 of $185.77/hr9 which is a blend of the calculated prosthetic formula rate of $205.94 and the orthotic formula rate of $165.59, this is a direct subsidy of $20.18 favouring orthotics and changes the potential for profit to 1% for prosthetics and 25% for orthotics. the article1 comments on subjects that are out of the scope of the aaop, and which have been eloquently addressed in a letter to the editor by orthotics prosthetics canada (opc).10 in summary, the article1 in question did not provide a complete historical account of the development of pricing models for orthotic and prosthetic services used today with the aadl in alberta. this letter aims to provide additional information and clarification on the opinion that prosthetics unfairly benefits at the expense of orthotics. it also provides the background of the development of our current pricing methodology and provides facts surrounding licensure. https://doi.org/10.33137/cpoj.v5i2.38313 https://opcanada.ca/ 4 pardy c, scott s, barnert j, reimer c. letter to the editor regarding: evolving business models in orthotics by schneider n. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.5. https://doi.org/10.33137/cpoj.v5i2.38313 canadian prosthetics & orthotics journal issn: 2561-987x letter to the editor pardy et al., 2022 there is a threat that exists for albertans with mobility impairment, coming from the blended rate and removing profit potential from prosthetics. as aadl apl’s fail to keep pace with material inflation, more of the costs will fall on the clients who can least afford it. the ability to respond to articles such as this one1, providing additional perspective, is important so that individuals in positions of authority in matters such as this can base their decisions on a complete spectrum of available information in order to prevent further erosion patients’ accessibility to life enhancing care and treatment. call to action while the article1 in question was, in our opinion not fully comprehensive it did broach a topic that merits more consideration. as orthotists and prosthetists, we need to continue to move away from being perceived to be providers of things, to the reality that we provide professional services to preserve our unique niche within the healthcare continuum. this has long been a goal of our national body, orthotics prosthetics canada, who have been working hard on this transition with the ongoing changes to exams and the national body itself with great success. a national coding guide that furthers this transition is the next logical step and merits discussion and action. pricing for orthotic & prosthetic care and treatment is a complicated matter as we function in an area of provincial jurisdiction, also interacting with federal programs and nationwide insurance providers. some provinces have established independent living programs that dictate pricing and service, but this is not universal in pricing formulae or benefits provided. further, we provide professional services to support individuals with mobility or physical impairment, but at the end of the day it is a device that enables these individuals to attain a level of restored function. the aaop pricing manner discussed in the article1 and this letter may not be perfect, but the structure does represent a substantial move away from device-based model to a professional services model as it is clear and transparent with all the pricing inputs. our understanding is that opc has initiated the process of developing a coding document that can be a reference for the provincial associations and to that end, aaop is putting our full support behind it. acknowledgements we would like to thank the following people for their contributions: ryan cochrane, cpo(c), and the many members of the aaop’s board of directors and stakeholder relations committee, as well as david moe, cp(c), fcbc and john rahman, co(c), for their invaluable contributions to this endeavour. declaration of conflicting interests connor pardy is currently past-president of the alberta association of orthotists and prosthetists (aaop), and was the president at the time of writing. connor pardy is currently on the board of directors of orthotics prosthetics canada (opc), and is a practicing certified prosthetist and orthotist at alberta orthotic and prosthetic centre. references 1.schneider n. evolving business models in orthotics. can prosthet orthot j. 2021; volume 4, issue 2, no.3. https://doi.org/10.33137/ cpoj.v4i2.35876 2.aadl approved product list: orthotic benefits [internet]. alberta health, 2021; [cited 2022, august 9]. available at: https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-80452498f464c2e3/resource/99cebd70-4063-4fa7-b4118b476f5b9619/download/healthaadl-manual-o-products-orthotic2021-10.pdf 3.aadl approved product list: prosthetic benefits [internet]. alberta health, 2021; [cited 2022, august 9]. available at: https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-80452498f464c2e3/resource/fef4d4aa-632f-4b9b-a907f35e5066947c/download/health-aadlmanual-p-productsprosthetic-2021-10.pdf 4.hammontree s, bradshaw l, fancher w, molnar g, scott g. american orthotic and prosthetic association. cost accounting manual. date unknown. 5.development of a professional fee guide for orthotists and prosthetists in alberta. date and author unknown. 6.taylor m. alberta aids to daily living, review of orthotist and prosthetist business arrangements [internet]. alberta seniors and community supports, 2008; [cited 2022, august 9]. available at: http://www.albertaoandp.com/uploads/files/member%20docs/merl e%20taylor%20report%202008.pdf 7.schneider m, toller j, allen j, calder k, faulkner b, schneider n (chair), final report. study of formula and fee schedule. alberta association of orthotists and prosthetists. april 21, 2003. 8.schneider n. braceworks custom orthotics. proposed pilot project: test application of service model under existing formula for orthotics. september 05, 2007. 9.aadl spreadsheet. aadl charge out rate – 2018 proposed rate, implemented 2019. 10.laakso l. letter to the editor regarding: evolving business models in orthotics. can prosthet orthot j. 2022; volume 5, issue 1, no.3. https://doi.org/10.33137/cpoj.v5i1.37717 citation pardy c, scott s, barnert j, reimer c. letter to the editor regarding: evolving business models in orthotics by schneider n. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.5. https://doi.org/10.33137/cpoj.v5i2.38313 keywords orthosis, prosthesis, prosthetics, orthotics, funding, economic, health care, aaop, aopa, aadl, orthotist, prosthetist, rehabilitation, mobility impairment https://doi.org/10.33137/cpoj.v5i2.38313 https://opcanada.ca/ http://www.albertaoandp.com/ http://www.albertaoandp.com/ https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/99cebd70-4063-4fa7-b411-8b476f5b9619/download/healthaadl-manual-o-products-orthotic-2021-10.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/99cebd70-4063-4fa7-b411-8b476f5b9619/download/healthaadl-manual-o-products-orthotic-2021-10.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/99cebd70-4063-4fa7-b411-8b476f5b9619/download/healthaadl-manual-o-products-orthotic-2021-10.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/99cebd70-4063-4fa7-b411-8b476f5b9619/download/healthaadl-manual-o-products-orthotic-2021-10.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/fef4d4aa-632f-4b9b-a907-f35e5066947c/download/health-aadlmanual-p-products-prosthetic-2021-10.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/fef4d4aa-632f-4b9b-a907-f35e5066947c/download/health-aadlmanual-p-products-prosthetic-2021-10.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/fef4d4aa-632f-4b9b-a907-f35e5066947c/download/health-aadlmanual-p-products-prosthetic-2021-10.pdf https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-8045-2498f464c2e3/resource/fef4d4aa-632f-4b9b-a907-f35e5066947c/download/health-aadlmanual-p-products-prosthetic-2021-10.pdf http://www.albertaoandp.com/uploads/files/member%20docs/merle%20taylor%20report%202008.pdf http://www.albertaoandp.com/uploads/files/member%20docs/merle%20taylor%20report%202008.pdf https://doi.org/10.33137/cpoj.v5i1.37717 https://doi.org/10.33137/cpoj.v5i2.38313 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 6, issue 1 2023 research article arnstein t, buis a. methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.7. https://doi.org/10.33137/cpoj.v6i1.42196 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v6i1.42196 1 arnstein t, buis a. methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.7. https://doi.org/10.33137/cpoj.v6i1.42196 research article methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation arnstein t, buis a* department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. introduction for people living with amputation, use of a prosthetic device facilitates functional restoration of the missing limb. ensuring safe load transfer between the prosthetic device and residual limb is critically important in successful rehabilitation. improper loading at this interface can cause discomfort and injury to the user’s residual limb. this is a common experience for people living with lower limb amputation1-3 that can result in reduced prosthesis use or device rejection, limiting mobility and hence the ability of users to carry out activities of daily living.4,5 furthermore, to remediate improper fit, additional devices are required to be manufactured placing increased strain on prosthetic care facilities and an additional burden on the user.1 as a result, improved interface design is consistently highlighted as a key requirement by prosthesis users worldwide.6 the prosthetic interface describes the socket and liner. the geometry and mechanical characteristics of these components play a significant role in dictating how load is transferred between the prosthetic device and residual limb. typically, a prosthetic socket is a quasi-rigid shell manufactured from a thermosetting or fibre-reinforced polymer. sitting in between the socket and residual limb, the prosthetic liner is an elastomeric or foam sleeve that allows some level of adaptability to reduce interface pressure concentrations. to accommodate the unique geometry, features, and behaviour of each residual limb, prosthetic sockets must be custom made devices. two distinct design open access abstract background: residual limb discomfort and injury is a common experience for people living with lower limb amputation. frequently, inadequate load distribution between the prosthetic device and the residual limb is the root cause of this issue. to advance our understanding of prosthetic interface fit, tools are needed to evaluate the mechanical interaction at the prosthetic interface, allowing interface designs to be evaluated and optimised. objectives: present a methodology report designed to facilitate comprehension of the mechanical interaction between the prosthetic interface and the residual limb. as a pilot study, this methodology is used to compare a hands-on and hands-off interface for a single transtibial prosthesis user using secondary magnetic resonance imaging (mri) data. methodology: mri data of the residual limb while wearing a prosthetic interface is segmented into a hard tissue and a skin surface model. these models are exported as stereolithography (stl) files. two methods are used to analyse the interface designs. firstly, cloudcompare software is used to compute the nearest vertex on the skin surface for every vertex on the compiled internal bony surface for both interface types. secondly, cloudcompare software is used to compare registered skin surfaces of the residual limb while wearing the hands-on and hands-off interfaces. findings: the maximum and minimum nearest distances between the internal bony surface and skin surface were similar between interface types. however, the distribution of nearest distances was different. when comparing the skin surface while wearing both interfaces, where the fit is more compressive can be visualized. for the dataset used in this study, the classic features of a hands-on patella tendon bearing interface and hands-off pressure cast interface could be identified. conclusion: the methodology presented in this report may give researchers a further tool to better understand how interface designs affect the soft tissues of the residual limb. article info received: december 14, 2023 accepted: january 10, 2024 published: january 17, 2024 citation arnstein t, buis a. methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.7. https://doi.org/10.33137/cpoj.v6i1 .42196 keywords prosthetic, interface, socket, mri, tissue strain, deformation, lower limb amputation, residual limb, rehabilitation, prosthesis, tissue deformation * corresponding author: arjan buis, phd department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. e-mail: arjan.buis@strath.ac.uk orcid id: https://orcid.org/0000-0003-3947-293x journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 1, article no.7. 2023 https://doi.org/10.33137/cpoj.v6i1.42196 https://doi.org/10.33137/cpoj.v6i1.42196 https://doi.org/10.33137/cpoj.v6i1.42196 mailto:arjan.buis@strath.ac.uk https://orcid.org/0000-0003-3947-293x https://jps.library.utoronto.ca/index.php/cpoj/index 2 arnstein t, buis a. methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.7. https://doi.org/10.33137/cpoj.v6i1.42196 canadian prosthetics & orthotics journal issn: 2561-987x effect of prosthetic interface design on residual limb soft tissue deformation arnstein t, and buis a, 2023 paradigms exist for prosthetic socket manufacture: handson and hands-off casting.7,8 hands-on casting refers to a clinician manually taking a cast of the residual limb and then rectifying this model to transfer load via purportedly load tolerant regions. within the hands-on category, computer aided design and manufacture (cad/cam) is becoming more prevalent with cad/cam systems trying to replicate clinician best practice. hands-off casting is where a pressurised vessel records the shape and volume that the residual limb takes. this method relies on the principle of hydrostatic load bearing whereby load is distributed across the residual limb more uniformly.9 theoretically, under this condition, pressure gradients and peaks are reduced, and less tissue shear generated. both hands-on and hands-off socket designs can achieve satisfactory clinical results.7,8 during prescription, interface fit is often assessed using tools that rely on user feedback and mobility performance testing.3,10 however, to develop more appropriate interface technology that is less likely to cause residual limb discomfort and injury, a better understanding of how socket design affects the mechanical conditions of the residual limb tissues is needed. presently, researchers often measure interface pressure to compare socket designs.11-13 while indicative of the mechanical conditions at the skin surface, interface pressure cannot be used to understand the mechanical conditions of the internal tissues. to go beneath surface level and get a better understanding of body device interface fit, tissue strain has been proposed as an important metric owing to its significance in soft tissue injury aetiology.14-16 within the tissues of the residual limb, strain can cause cellular death through direct mechanical insult, ischemia, reperfusion, and impaired lymphatic drainage.17 researchers have presented tools to interrogate the internal mechanical conditions of soft tissues, within prosthetics and more widely the rehabilitation field. finite element analysis (fea) of the residual limb allows internal mechanical conditions to be studied.18 as the complexity of fea models have increased, and more accurate material models and boundary conditions included, more confidence can be placed in these results. however, inherent limitations remain including the lack of material models that sufficiently accurately represent the biological materials of the residual limb. furthermore, state of the art models demand significant computing resource and take a long time to set -up and complete making it currently unviable to conduct for large populations or in clinical settings.19 digital image correlation (dic) and digital volume correlation (dvc) have also been proposed as tools to investigate residual limb tissue strains. 3d-dic was used to record residual limb surface deformation which could then be used to calculate gross tissue deformation.20 however, this can only be conducted while no socket is worn, and the position of internal structures cannot be recorded. rankin et al. manufactured an analogue residual limb consisting of bone structures and an elastomer filled with sand particles to represent the soft tissues.21 dvc of the analogue residual limb, using computer tomography (ct) imaging, was then performed while wearing two socket types. the authors suggested that the clinical translatability of this method was poor and questions remain about how the sand particles affect the behavior of the elastomer, and how representative this composite is of biological tissue. researchers have previously used the bone to skin surface distance when assessing body interfacing assistive technology designs in 2d22 and 3d.23-25 changes in bone to skin distance infer the occurrence of tissue deformation. to the best of our knowledge, in the field of prosthetics, bone to skin distance in 3d has not been used as a tool to assess socket fit. this report details a methodology to calculate, present, and evaluate the distance between the internal bony surface and skin surface of a residual limb. using this information, interface designs can then be compared. as a pilot study, this methodology is used to compare a hands-on patellar tendon bearing (ptb) socket and hands-off pressure cast socket for a single transtibial prosthesis user using secondary magnetic resonance imaging (mri) data. methodology from mri data to 3d stl models mri images of one person with unilateral transtibial amputation were retrieved from a secondary dataset to use in this study (figure 1).26 the mri data used was randomly selected from 12 potential participants. all data had been previously anonymised, and hence ethical approval was not required. two mri datasets were used from the same participant; one of the participant’s residual limb while wearing a hands-on cast interface and one while wearing a hands-off cast interface. the mri parameters used were as follows; field intensity 3 t, repetition time 6.9 s, time of echo 1.5 s, inversion time 500 ms, bandwidth 31.25 khz, flip angle 12 deg, matrix 256 × 256, slice thickness 1.2 mm, voxel dimensions 1.17 × 1.17 × 0.6 mm, and a 1-signal average.26 the residual limb was fixed in position during the scanning procedure by placing the patellar in a knee-cap receptacle and harnessing the thigh using pads and strapping. the mri data was imported into 3d slicer 5.2.2 medical image processing software.27 the following anatomical structures were segmented and extracted from the mri datasets: •soft tissue •meniscus and patellar tendon •femur •patella •tibia •fibula https://doi.org/10.33137/cpoj.v6i1.42196 3 arnstein t, buis a. methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.7. https://doi.org/10.33137/cpoj.v6i1.42196 canadian prosthetics & orthotics journal issn: 2561-987x effect of prosthetic interface design on residual limb soft tissue deformation arnstein t, and buis a, 2023 figure 1: mri image in coronal plane of participants residual limb showing femur, tibia, and soft tissues. figure 2: stl model of participants residual limb. hard tissue surface is shown in green. skin surface is shown in orange. segmentation was performed semi-automatically using the ‘grow from seeds’ tool and then manually cleaned. the soft tissue segmentation included the skin, muscles, adipose, and connective tissues of the residual limb. the meniscus and patellar tendon were not included in the soft tissue structure as these are taken to be internal bodies that should be included in the hard tissue structure. the meniscus and patellar tendon were segmented together because of the challenge of processing individually. the other bony structures were segmented separately. models were exported as stereolithography (stl) surface models. for each scan, the bone structures and meniscus/patellar tendon assembly were compiled into one stl file using gmsh© model meshing software.28 this structure is hereby referred to as the hard tissue surface. this structure formed the surface for the nearest distance to the skin surface to be calculated from. the skin surface, being the outer surface of the soft tissue segmentation, was kept as a separate model (figure 2). the internal bone surface model was trimmed 50mm proximally to the most distal point on the femoral condyles. this represented a distance more proximal than the most proximal point on the socket brim across both interface types, ensuring all tissue encapsulated by an interface was included. the trim command was repeated for the skin surface using the same trim plane with reference to the global coordinate system. cloudcompare software was used to calculate the distances between the stl vertices on paired surfaces using the nearest neighbour distance approach. for the first method of analysis, for each vertex on the internal bony surface, the corresponding nearest vertex on the skin surface is found and distance computed. for the second method of analysis, the hands-on and hands-off skin surfaces are registered and then distances between surfaces calculated. a description of each method is provided below: internal bony surface to skin surface nearest distance; comparison between interface types. for each socket type, the distance from every vertex on the internal bony surface to the nearest vertex on the skin surface is computed. a histogram of the distribution of surface-to-surface distances is retrieved from cloudcompare with the nearest distances split into 100 intervals. this process is repeated for both socket types. the number of nearest distance measurements for each socket type is then normalised to correct for discrepancies in the number of vertices of each stl file. the histogram for the hands-on and hands-off sockets are then combined into one graph. hands-on interface vs. hands-off interface; skin surface visual comparison. using gmsh© software, a new stl file is created for both socket types that contains the skin surface and tibia surface only. these are loaded onto the cloudcompare interface. next, the skin surface is separated from the tibia surface using the segment tool. once complete, the tibia models are registered by aligning 10 manually selected equivalent point pairs. to ensure good registration, points are selected at key anatomical features that are easy to identify, and also at the extremities of the bone models. finally, the tibia models are finely registered using cloudcompare’s inbuilt fine registration tool. the quality of registration is quantified by calculating the absolute and average hausdorff https://doi.org/10.33137/cpoj.v6i1.42196 4 arnstein t, buis a. methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.7. https://doi.org/10.33137/cpoj.v6i1.42196 canadian prosthetics & orthotics journal issn: 2561-987x effect of prosthetic interface design on residual limb soft tissue deformation arnstein t, and buis a, 2023 distances, a measure of similarity between shapes. the skin surfaces are then reinstated, and the nearest neighbour method is used to calculate the distance between both skin surfaces. the results are displayed as a heat map on the original skin surface. this process is then repeated with the other interface type as the reference surface and heat map inverted. the skin surfaces from both interface types are overlaid to allow the difference in surface topology to be visualised. results internal bony surface to skin surface nearest distance; comparison between interface types (figure 3). the nearest distance between the internal bony surface and skin surface, for every surface vertex, was calculated for both interface types: while wearing a hands-on interface and while wearing a hands-off interface. for the hands-on and hands-off interfaces, the maximum nearest distances between the internal hard tissue structure and skin surface were similar at around 60mm. the smallest nearest distances between the internal hard tissue structure and skin surfaces were in the order of 1mm for both sockets. for the hands-on socket, 4.4% of the skin surface was between 7.8mm and 8.4mm from the internal bony surface, representing the most common distance for this condition. for the hands-off socket, 3.2% of the skin surface was between 9mm and 8.6mm from the internal hard tissue structure, representing the most common distance for this condition. when comparing the hands-on interface to the hands-off interface, the hands-on interface has a higher peak that is positioned further left along the x-axis. in contrast, the hands-off interface has a lower peak that is positioned further right along the x-axis. a greater proportion of the hands-off interface skin surface is found to be further away from the internal bony surface as seen at the right extremity of the x-axis (figure 3). hands-on interface vs. hands-off interface; skin surface visual comparison (figure 4). after registration of the tibia models, the absolute bidirectional hausdorff distance was 2.81mm and the average bidirectional hausdorff distance was 0.43mm. the resulting skin surface geometries for the hands-on and hands-off interface types were compared. areas highlighted in red show where the hands-on interface has a more compressive fit than the hands-off interface. areas highlighted in blue show where the hands-off interface has a more compressive fit than the hands-on interface. the hands-on interface has a more compressive fit at the distal end of the residual limb, across the patellar tendon, above the medial and lateral femoral epicondyles. the hands-off interface has a more compressive fit more proximally on the residual limb, specifically on the anterior aspect. figure 3: this graph shows percentages of the skin surface that are within a certain distance from the bone surface. the hands-off socket is shown in black/blue, and the hands-on socket is shown in gray/red. discussion the methods proposed in this report indicate deformation of residual limb soft tissues. the first method of analysis can be used to help understand how uniformly an interface design deforms residual limb soft tissue. the second method of analysis can be used to visualise where on the residual limb a socket design is more compressive and where the fit is more relaxed. this information can be used as a further tool to improve interface fit by providing a better understanding of how interface designs affect the soft tissues of the residual limb. internal bony surface to skin surface nearest distance; comparison between interface types. the histogram profile is suggestive of interface fit. while wearing the hands-on interface, the higher peak of the histogram, positioned further left along the x-axis, points to higher levels of deformation, and hence strain, being induced in a larger volume of the residual limb than compared to the hands-off interface. in contrast, for the hands-off interface, the lower peak positioned further right along the x-axis suggests that this interface delivers a more uniformly compressive fit. a shorter distance between the internal bony surface and skin surface describes a smaller depth of soft tissue. at these smaller distances, less absolute deformation is required to induce higher, possibly dangerous, levels of tissue strain. there is a greater volume of residual limb in the first three intervals of the histogram (<1.8mm soft tissue depth) for the hands-on condition than for the hands-off condition. while a comparison to the no-socket condition cannot be made for this study, the more compressive fit over areas of shallow tissue depth for the hands-on condition indicates that high tissue strain levels will be generated. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 60distance from bone to skin surface (mm) hands-off interface hands-on interface s u rf a c e a re a o f re s id u a l lim b ( % ) https://doi.org/10.33137/cpoj.v6i1.42196 5 arnstein t, buis a. methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.7. https://doi.org/10.33137/cpoj.v6i1.42196 canadian prosthetics & orthotics journal issn: 2561-987x effect of prosthetic interface design on residual limb soft tissue deformation arnstein t, and buis a, 2023 hands-on interface vs. hands-off interface; skin surface visual comparison. much of what is shown in figure 4 agrees with hands-on and hands-off interface fit that has been reported in the literature. the classic features of the hands-on ptb socket, such as the patellar tendon bar, popliteal depression, and medial and lateral supracondylar depressions can be easily identified.29 the longer residual limb length while wearing the hands-off cast is also in agreement with previously reported literature.26 this suggests that the participants residual limb, and hands-on and hands-off casts, were fairly typical. surprisingly there is no observable difference in socket geometry over the fibular head, a sensitive feature of the residual limb where offloading is commonly included as part of hands-on design.30 however, due to the small tissue depth over the fibular head, whether this methodology is sensitive enough to pick up any difference should be questioned. interface pressure is commonly visualised using heatmaps31,32 but deformation or topology, as reported here, is less common with few examples.29 considerations and future work the nearest distance between the internal bony surface and skin surface, and skin surface to skin surface comparison between interface types, indicates deformation of residual limb soft tissues. however, the distribution of strain within residual limb tissues cannot be ascertained. furthermore, whether a structure is at higher risk of tissue damage is not taken into consideration. different tissues have different mechanical properties, discomfort or damage thresholds, and the makeup of different tissue types in an area of residual limb is not considered.18 there are also amputation specific factors that aren’t included such as the presence of scarring33 or an already compromised vascular system. the process of converting the mri scans into stl models requires multiple steps, during which, some geometric accuracy is likely lost. this is especially pertinent when investigating structures with smaller soft tissue depths, nearing the resolution of the mri data, where a loss in accuracy will have a big impact on the resulting error. high definition mri data allows for more accurate segmentation. for future studies, what counts as sufficiently highresolution mri data, must be defined. this should be noted as a significant limitation in this pilot study as the quality of the secondary mri data was poor. during ambulation, prostheses are loaded dynamically and movement of the residual limb bones with respect to the socket wall occurs.34 the methodology presented in this report only looks at a static loading condition. using this methodology to compare different levels of static loading while wearing the same interface would go some way to understanding how different interface designs influence residual limb soft tissue deformation during prostheses use. comparing the geometry of the residual limb while wearing prosthetic devices against wearing no device would be of interest. unfortunately, mri images of the participant’s residual limb with no interface donned were not available for this study. collecting mri data of the residual limb without significant distortion of the tissues due to gravity is challenging. for this reason, imaging the residual limb while wearing only a liner to reduce sagging might be better suited as a baseline condition for comparison. this pilot study only reports on a single participant and therefore the results cannot be generalised to a wider figure 4: comparison of skin surface while wearing hands-on and hands-off interface using method 2. areas where hands-on interface provides a more compressive fit when compared to the hands-off interface are shown in red. areas where hands-off interface provides a more compressive fit when compared to the hands-on interface are shown in blue. hands-off hands-on https://doi.org/10.33137/cpoj.v6i1.42196 6 arnstein t, buis a. methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.7. https://doi.org/10.33137/cpoj.v6i1.42196 canadian prosthetics & orthotics journal issn: 2561-987x effect of prosthetic interface design on residual limb soft tissue deformation arnstein t, and buis a, 2023 population. future work should focus on validating this methodology by comparing results to a range of other measures, for a larger study population to look for patterns in tissue deformation caused by interface fit, and including the liner-only condition. conclusion the methodology presented in this report may give researchers a further tool to better understand how interface designs effect the soft tissues of the residual limb. when used to compare the residual limb of a single participant while wearing a hands-on and hands-off interface, differences in the distribution of nearest internal bony surface to skin surface distances were observed. a further study comparing interface designs to no prosthesis or liner only condition should be completed, upon which it will be possible to have more confidence in this technique. attaining a complete understanding of the biomechanics of the residual limb and its interaction with prosthetic devices remains an unsolved challenge that limits the advancement of prosthetic interface design. acknowledgements the authors would like to acknowledge 3d slicer (www.slicer.org)27 and gmsh (https://gmsh.info/).28 the authors would also like to thank the epsrc centre for doctoral training in prosthetics & orthotics for its support. declaration of conflicting interests the authors report that there are no conflicts of interest to declare. authors contribution thomas arnstein conceived the idea, conducted the research, and drafted the manuscript, while arjan buis provided supervision. both authors actively participated in the discussion of results and contributed to the manuscript's revisions. sources of support epsrc grant number: ep/s02249x/1 references 1.turner s, mcgregor ah. perceived effect of socket fit on major lower limb prosthetic rehabilitation: a clinician and amputee perspective. arch rehabil res clin transl. 2020;2(3):100059. doi:10.1016/ j.arrct.2020.100059 2.pezzin le, dillingham tr, mackenzie ej, ephraim p, rossbach p. use and satisfaction with prosthetic limb devices and related services. arch phys med rehabil. 2004;85(5):723-9. doi: 10.1016/ j.apmr.2003.06.002 3.hanspal rs, fisher k, nieveen r. prosthetic socket fit comfort score. disabil rehabil. 2003;18;25(22):1278-80. doi: 10.1080/ 09638280310001603983 4.hagberg k, brånemark r. consequences of 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[cited 2023 dec 15]. available from: https://www.peoplepoweredprosthetics.com/projects/voices/ 7.dumbleton t, buis a, mcfadyen a, mchugh b, mckay g, murray k, et al. dynamic interface pressure distributions of two transtibial prosthetic socket concepts. j rehabil res dev. 2009;46:405-15. 8.suyi yang e, aslani n, mcgarry a. influences and trends of various shape-capture methods on outcomes in trans-tibial prosthetics: a systematic review. prosthet orthot int. 2019;43(5):540-55. doi: 10.1177/0309364619865424 9.kristinsson o. the iceross concept: a discussion of a philosophy. prosthet orthot int. 1993;17(1):49-55. doi:10.3109/ 03093649309164354 10.won ny, paul a, garibaldi m, baumgartner re, kaufman kr, reider l, et al. scoping review to evaluate existing measurement parameters and clinical outcomes of transtibial prosthetic alignment and socket fit. prosthet orthot int. 2022;46(2):95-107. doi:10.1097/pxr. 0000000000000061 11.safari r. lower limb prosthetic interfaces: clinical and technological advancement and potential future direction. prosthet orthot int. 2020;44(6):384-401. doi: 10.1177/0309364620969226 12.safari mr, meier mr. systematic review of effects of current transtibial prosthetic socket designs-part 2: quantitative outcomes. j rehabil res dev. 2015;52(5):509-26. doi: 10.1682/jrrd. 2014.08.0184 13.pirouzi g, abu osman na, eshraghi a, ali s, gholizadeh h, wan abas wa. review of the socket design and interface pressure measurement for transtibial prosthesis. scientificworldjournal. 2014;2014:849073. doi: 10.1155/2014/849073 14.mak af, zhang m, tam ew. biomechanics of pressure ulcer in body tissues interacting with external forces during locomotion. annu rev biomed eng. 2010;12:29-53. doi: 10.1146/annurev-bioeng-070909105223 15.bader dl, worsley pr, gefen a. bioengineering considerations in the prevention of medical device-related pressure ulcers. clin biomech (bristol, avon). 2019;67:70-7. doi:10.1016/j.clinbiomech.2019.04.018 16.mak af, zhang m, boone da. state-of-the-art research in lower-limb prosthetic biomechanics-socket interface: a review. j rehabil res dev. 2001;38(2):161-74. 17.graser m, day s, buis a. exploring the role of transtibial prosthetic use in deep tissue injury development: a scoping review. bmc biomed eng. 2020;2:2. doi:10.1186/s42490-020-0036-6 18.dickinson as, steer jw, worsley pr. finite element analysis of the amputated lower limb: a systematic review and recommendations. med eng phys. 2017;43:1-18. doi:10.1016/j.medengphy.2017.02.008 19.ranger bj, moerman km, anthony bw, herr hm. constitutive parameter identification of transtibial residual limb soft tissue using ultrasound indentation and shear wave elastography. j mech behav biomed mater. 2023;137:105541. doi:10.1016/j.jmbbm.2022.105541 20.solav d, moerman km, jaeger am, herr hm. a framework for measuring the time-varying shape and full-field deformation of residual limbs using 3-d digital image correlation ieee trans biomed eng. 2019;66(10):2740-52. doi:10.1109/tbme.2019.2895283 https://doi.org/10.33137/cpoj.v6i1.42196 http://www.slicer.org/ https://gmsh.info/ https://www.peoplepoweredprosthetics.com/projects/voices/ 7 arnstein t, buis a. methodology to investigate effect of prosthetic interface design on residual limb soft tissue deformation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.7. https://doi.org/10.33137/cpoj.v6i1.42196 canadian prosthetics & orthotics journal issn: 2561-987x effect of prosthetic interface design on residual limb soft tissue deformation arnstein t, and buis a, 2023 21.rankin k, steer j, paton j, mavrogordato m, marter a, worsley p, et al. developing an analogue residual limb for comparative dvc analysis of transtibial prosthetic socket designs. materials (basel). 2020;13(18). doi:10.3390/ma13183955 22.call e, hetzel t, mclean c, burton jn, oberg c. off loading wheelchair cushion provides best case reduction in tissue deformation as indicated by mri. j. tissue viability. 2017;26(3):172-9. doi:10.1016/j.jtv.2017.05.002 23.linder-ganz e, shabshin n, itzchak y, gefen a. assessment of mechanical conditions in sub-dermal tissues during sitting: a combined experimental-mri and finite element approach. j biomech. 2007;40(7):1443-54. doi:10.1016/j.jbiomech.2006.06.020 24.brienza d, vallely j, karg p, akins j, gefen a. an mri investigation of the effects of user anatomy and wheelchair cushion type on tissue deformation. j. tissue viability. 2018;27(1):42-53. doi: 10.1016/j.jtv.2017.04.001 25.sonenblum se, ma j, sprigle sh, hetzel tr, mckay cathcart j. measuring the impact of cushion design on buttocks tissue deformation: an mri approach. j. tissue viability. 2018;27(3):162-72. doi: 10.1016/j.jtv.2018.04.001 26.safari r, rowe p, mcfadyen a, buis a. hands-off and hands-on casting consistency of amputee below knee sockets using magnetic resonance imaging. thescientificworldjournal. 2013;2013:486146. doi: 10.1155/2013/486146 27.fedorov a, beichel r, kalpathy-cramer j, finet j, fillion-robin j-c, pujol s, et al. 3d slicer as an image computing platform for the quantitative imaging network. magn reson imaging. 2012;30(9):132341. doi: 10.1016/j.mri.2012.05.001 28.geuzaine c, remacle j.f. gmsh: a three-dimensional finite element mesh generator with built-in preand post-processing facilities. int j numer methods eng. 79(11), pp. 1309-1331, 2009. doi:10.1002/ nme.2579 29.dickinson a, diment l, morris r, pearson e, hannett d, steer j. characterising residual limb morphology and prosthetic socket design based on expert clinician practice. prosthesis. 2021;3:280-99. doi:10.3390/prosthesis3040027 30.craelius w. limb-prosthetic interface. in: craelius w, editor. prosthetic designs for restoring human limb function. cham: springer international publishing; 2022. p. 133-53. 31.turner s. visualising socket pressure in lower-limb prostheses [doctoral thesis]. imperial college london, 2021. 32.hopkins mo, turner s, vaidyanathan r, mcgregor a. mapping lower-limb prosthesis load distributions using a low-cost pressure measurement system. front. med. technol. 2022;4. doi:10.3389/fmedt.2022.908002 33.portnoy s, siev-ner i, yizhar z, kristal a, shabshin n, gefen a. surgical and morphological factors that affect internal mechanical loads in soft tissues of the transtibial residuum. ann biomed eng. 2009;37(12):2583-605. doi: 10.1007/s10439-009-9801-3 34.baumann m, price c, brousseau l, loftsgaarden m, powell j, sanders j, et al. the relationship between residual limb health, motion within the socket, and prosthetic suspension. pm r. 2023 apr;15(4):510-521. doi: 10.1002/pmrj.12899 https://doi.org/10.33137/cpoj.v6i1.42196 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 6, issue 1 2023 literature review costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v6i1.42170 1 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 literature review peer support for individuals with major limb loss: a scoping review costa-parke a1, di lella a.m1, walker a2, verweel l2*, mackay c2, 3 1 department of occupational science and occupational therapy, university of toronto, toronto, canada. 2 west park healthcare centre, toronto, canada. 3 department of physical therapy, university of toronto, toronto, canada. introduction major limb loss is the partial or total amputation of an extremity that occurs at and/or above the ankle or wrist.1 this type of amputation may result from diabetes or other vascular conditions, a traumatic event, cancer, or a congenital condition.2 living with major limb loss can have profound physical implications for the individual.3 evidence has shown that people with major limb loss experience reduced physical function, mobility, and pain.3 while the consequences of amputation can lead to physical and mobility limitations, research has suggested that psychosocial and mental health outcomes are also significant barriers to effective recovery post-amputation. people with limb loss can experience grief, social isolation, loss of self-esteem,3-6 and higher rates of depression, anxiety, and body image disorders.7 limb loss is also known to impact social interactions, community participation, and engagement in daily activities.3,6 these challenges can negatively impact an individual's quality of life and psychosocial well-being.6 despite substantial evidence of the psychosocial impacts of amputation8,9 rehabilitation programs often focus on physical recovery with limited resources targeting psychosocial support. peer support is a non-medical intervention that offers a supportive relationship between individuals who have shared experiences with a condition.10,11 peer support has been shown to be an important component in the care of individuals dealing with various health conditions, such as substance abuse12 and mental health illnesses.12,13 fortuna open access abstract background: major limb loss can have profound physical and psychosocial implications for individuals, impacting their quality of life and well-being. despite the effectiveness of peer support in improving outcomes for various chronic conditions, its impact on individuals with major limb loss remains understudied. objective(s): this review aims to explore the existing literature on peer support for individuals with major limb loss. specifically, exploring how the literature defines peer support; examining its implementation, identifying outcomes measured in peer support interventions, assessing the benefits for individuals with major limb loss, and identifying barriers associated with peer support provision. study design: this review followed arksey and o’malley’s methodological framework, analysing relevant literature to identify evidence, definitions, and key factors related to peer support for individuals with major limb loss. methodology: a comprehensive search in january 2023 utilized databases: medline, psychinfo, embase, and cinahl. after a two-phase screening process, articles meeting specific criteria were included. thematic and descriptive numerical analyses were applied to the extracted data. findings: twenty-two articles were reviewed. peer support was described as an opportunity to provide education, advice, and encouragement between individuals with lived experiences. across the two intervention-based studies investigating peer support programs, outcome measures included physical, psychological, social, and quality of life. qualitative studies described perceived benefits as improved psychosocial well-being and the opportunity to exchange knowledge. perceived barriers included a lack of formal training and male-dominated groups, which deterred individuals with amputation from participating. conclusion: the evidence from the findings of the review sheds light on the current understanding of peer support for individuals with amputation. due to the limited number of studies available, future research is necessary to develop and evaluate the effectiveness of peer support interventions tailored to this population. article info received: december 7, 2023 accepted: december 24, 2023 published: december 28, 2023 citation costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i 1.42170 keywords amputation, peer support, limb loss, scoping review, social support, prosthesis, rehabilitation * corresponding author: lee verweel, bsc, msc west park healthcare centre, toronto, canada. e-mail: lee.verweel@westpark.org orcid id: https://orcid.org/0000-0002-3363-8161 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 1, article no.6. 2023 https://doi.org/10.33137/cpoj.v6i1.42170 https://doi.org/10.33137/cpoj.v6i1.42170 https://doi.org/10.33137/cpoj.v6i1.42170 mailto:lee.verweel@westpark.org https://orcid.org/0000-0002-3363-8161 https://jps.library.utoronto.ca/index.php/cpoj/index 2 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 et al.13 used peertech, a peer support program supplemented by technological use, and found improvements in quality of life, self-management, and selfefficacy for managing health conditions, including mental illnesses such as schizophrenia and bipolar disorders, and comorbidities like diabetes and cardiovascular disease. proudfoot et al.14 examined the inclusion of peer support in a psychoeducational program and found that the peer support programs led to greater adherence to treatment compared to the unsupported program. in addition, the peer support group led to decreases in stigmatization, a reduction in anxiety and depression.14 similarly, individuals with diabetes reported that community-based peer support programs led by trained peers showed improvements in symptoms of depression, communication with healthcare practitioners, healthier lifestyle behaviours and increased self-efficacy.15 although there is a breadth of evidence available about peer support among other populations with chronic conditions (e.g., diabetes, mental illnesses), less is known about the nature and scope of research on peer support for individuals living with major limb amputation. a scoping review on peer support for trauma survivors, which included individuals with traumatic amputations, found that peer support provided trauma survivors with socioemotional support as well as assistance in daily management and life navigation postinjury.16 however, studies of peer support following trauma may not be transferable to all individuals with limb loss, most of whom have amputations due to diabetes.17 to address this gap, the purpose of this scoping review was to examine the extent, nature, and scope of existing literature on peer support for people living with major limb loss to inform future research and practice. methodology a scoping review was performed to identify existing literature and clarify the definitions and key factors associated with this topic.18 the review followed arksey and o’malley’s five-stage methodological framework, which outlines: (i) identifying the research questions; (ii) identifying relevant studies; (iii) study selection; (iv) charting the data; and (v) collating, summarizing, and reporting the results.19 identifying research question (stage 1) the research questions used to guide the review were: (1) how does the current literature define peer support? (2) how has peer support been implemented (e.g., programs, interventions, informal supports) and at what stage (e.g., acute care, rehab, community)? (3) what are the outcomes measured in peer support interventions? (4) what are the benefits of peer support for the quality of life of individuals with major amputations, and (5) what are the risks or barriers to the provision of peer support? identifying relevant studies (stage 2) literature searches were conducted in a period spanning january 2023 to april 2023 using the electronic databases of medline, psychinfo, embase, and cinahl. the search strategy was customized to each database and used key terms that included “peer support”, “amputation”, and “major limb loss” (see appendix a-d for search strategies). to supplement these searchers, a hand search of reference lists of retrieved articles was also conducted to scan for additional relevant studies. the four databases and handsearched articles were uploaded to the software covidence. a two-phase screening process was conducted; the first involved the elimination of articles based on title and abstract, and the second involved a full-text review. to establish inter-rater reliability, two authors (di lella a.m and costa-parke a) separately conducted each phase and then met to reach a consensus. disagreements between reviewers were resolved by consensus or by the decision of a third reviewer (mackay c). study selection (stage 3) the following inclusion criteria were used to guide the search and retrieve the articles: (1) published in the english language; (2) individuals with a major amputation, including trauma-related, surgical-related (cancer, infection, vascular, etc.), and congenital; (3) age range: 18 years and older; (4) studies should include some aspect of peer support, either formal or informal; (5) participants have either received peer support or provided peer support (with or without training); (6) articles should include primary data. articles were excluded if: (a) they focused on minor limb amputations; (b) they focused on amputations in youth populations; (c) dissertations, study protocols, editorials, and conference proceedings. charting the data (stage 4) the data-charting form was developed using an excel sheet by two authors (di lella a.m and costa-parke a) to maintain the consistency of the variables being extracted. the authors independently extracted the data and met to reach a consensus on the variables. the data extracted were summarized and inputted into tables that included: (i) study details (e.g., title, authors, year, country); (ii) population characteristics and eligibility (e.g., type of major limb amputation); (iii) study design/methodology (e.g., study objectives, types of measures used); (iv) peer support (e.g., definition, delivery method, practice setting); and (v) major findings (e.g., how studies define peer support, outcome measures, risks, and benefits). collecting, summarizing and reporting the results (stage 5) after charting information from included studies, we produced a narrative account of findings in two ways. first, quantitative analysis was conducted including a frequency https://doi.org/10.33137/cpoj.v6i1.42170 3 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 analysis of the extent, nature and distribution of the studies included in the review. second, the findings were organized thematically. we used a descriptive approach which involved allocating concepts or characteristics relevant to each research objective into overall categories. this included comparing information across studies, combining similar concepts, and summarizing ideas. two authors (di lella a.m and costa-parke a) independently categorized data extracted from the articles to summarize the key ideas identified across articles and later met to reach a consensus on the findings. other members of the research team were consulted to enhance validity and reduce biases in the results of the study. results overview of study characteristics a total of 1103 articles were identified from four databases, and after duplicates were removed, 688 articles remained. the two authors (di lella a.m and costa-parke a) separately screened the titles and abstracts of the articles and a total of 147 were deemed eligible for full text review. two authors (di lella a.m and costa-parke a) individually conducted a full-text review of these 147 and a total 22 articles met the inclusion criteria (figure 1). articles reported primary data using qualitative methods (n=16), randomized controlled trials (rct) (n=2), crosssectional studies (n=2), cost-analysis (n=1), and noncontrolled retrospective cohort study (n=1). studies were conducted in canada (n=4), the united states of america (n=7), australia (n=4), the united kingdom (n=2), the democratic republic of congo (n=1), scotland (n=1), taiwan (n=1), and iran (n=1). one of the studies by anderson et al.20 was conducted in both the united kingdom and australia. the types of amputations discussed among the articles included participants with major lower extremity loss (n=15) or both major lower and upper extremity loss (n=7). two studies reported on the effects of a peer support intervention. seven articles explored the impacts of peer support as a primary objective, and 13 articles explored peer support as a secondary or other finding (i.e., the articles did not study peer support but generated findings that demonstrated peer support as relevant to its participants). see the full study details in table 1. definition of peer support of the articles included in this study (n=22), there were only six that defined peer support, and these definitions varied in their explanations. three studies described peers as a group of individuals who have experienced a major limb amputation.21-23 peer support involved individuals with amputation sharing their lived experiences, either one-onone or between groups of individuals. 21,22,24-26 observing peers further along in their amputation recovery was defined as a form of peer support.21 three articles indicated that peer support was an opportunity for amputees to educate each other on how to engage in activities of daily living.22,24,26 this included guidance on improving mobility and functionality, such as walking on uneven surfaces, moving through crowds and navigating stairs.25 in addition, amputees were able to receive emotional and moral support from their peers by providing inspiration and encouragement.22,26 implementation of peer support twelve studies discussed the types of settings in which peer support may be implemented. seven of these studies described programs implemented in community settings, including charities, organizations, and clinics.21,22,24,27-30 four studies described programs facilitated in rehabilitation settings.25,31-33 while one study discussed peer support being implemented within a hospital and community setting.34 fifteen studies described the method by which peer support programs are delivered, which varied between formal and informal delivery formats. eight studies outlined structured delivery methods in which participants engaged in organized peer support sessions led by a peer volunteer, with or without prior training in delivering peer support. 21,24,27-30,34,35 seven studies characterized informal delivery approaches, depicting them as a natural and chance encounter with another amputee, where the opportunity for knowledge and sharing of experiences could be exchanged.24,25,31-34,36 outcomes in peer support interventions the effect of using peer support as a study intervention was explored by two rcts.29,30 physical health outcomes were measured using the short musculoskeletal function assessment, chronic pain grade questionnaire,29 and brief pain inventory,30 which allowed for the assessment of musculoskeletal function and pain, respectively. the studies also examined psychological well-being outcomes such as depression, affect, and self-efficacy, including: the patient health questionnaire depression module,29 the centre for epidemiologic studies depression,30 positive and negative affect schedule,30 positive states of mind,30 and a modified self-efficacy scale.30 social support outcomes were assessed using a multidimensional scale of perceived social support. lastly, the studies examined quality of life as an outcome, and this was assessed using the world health organization quality of life scale29 and satisfaction with life scale.30 benefits of peer support all 22 articles included in this scoping review discussed the physical or psychosocial benefits of the provision of peer support. https://doi.org/10.33137/cpoj.v6i1.42170 4 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 improved physical functioning two rcts29,30 reported on the impact of peer support on physical function. wegener et al.30 reported that participants experienced a decrease in functional limitations six months following their participation in a peer support intervention. however, turner et al.29 did not report an improvement; nevertheless, the authors noted possible explanations to be a lower physical baseline prior to study involvement as the participants were older adults.29 enhanced psychological well-being four studies explored the benefits of psychological wellbeing; these included two studies that examined peer support as a secondary objective32,37 and two rcts.29,30 three studies reported that peer support involvement led to a reduction in symptoms of depression in their participants.29,30,36 while liu et al.31 found that talking to peers provided an opportunity to alleviate emotional distress. nineteen reported on the perceived benefits of social support and connectedness. the majority of these studies discussed how peer support provided an opportunity for participants to share experiences and give advice to each other, which allowed them to build social connections and aided in their recovery transition.20,22-28,33-35,37-41 studies have also reported that peer support groups facilitate the exchange of knowledge and education on how to engage in daily life with an amputation, which is perceived to be more beneficial than support from a clinician.21,24,28,34,35,37,40 ten of these articles discussed how engagement in amputee peer support groups provided participants with feelings of optimism and hope for the future.21-25,31,36,38 amorelli et al.21 reported that when participants observed other individuals with amputation engage in daily activities, they felt hopeful that they could still enjoy life like they once had. likewise, richardson et al.22 discussed how peer studies from databases/registers (n = 1103) references removed (n = 415) duplicates identified manually (n = 23) duplicates identified by covidence (n = 392) studies screened (n = 688) studies excluded (n = 541) studies assessed for eligibility (n = 147) reports excluded (n = 125): ineligible study design (n = 39) ineligible outcomes (n = 12) non-peer support intervention (n = 12) not written in english (n = 2) ineligible patient population (n = 4) peer support not included (n = 56) studies included in review (n = 22) id e n ti fi c a ti o n s c re e n in g in c lu d e d e li g ib il it y figure 1: prisma diagram. https://doi.org/10.33137/cpoj.v6i1.42170 5 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 support helped participants see that meaningful engagement in life can continue even after limb loss. seven articles discussed how amputee peer support groups facilitated the building of friendships and communities beyond those of family and non-amputee friends.22,24,31,36,3941 the relationships built while engaging in peer support groups were reported by three studies to have reduced the perceived social isolation participants felt after experiencing their amputation.24,31,37 two articles also discussed how the relationships built in peer support groups provided individuals with amputation with emotional and social support.33,39 community participation and engagement the impact of peer support on re-engaging in daily activities post-amputation was discussed in two qualitative studies.21,38 amorelli et al.21 studied peer support as a primary objective, and both studies reported that the advice and support received from peers inspired participants' engagement in the community and daily activities.38 impact on self-management, self-efficacy and well-being four of the studies reported on the perceived benefit that peer support had an impact on self-management and wellbeing.27,30,32,37 participants reported that this type of social support boosted their self-esteem, confidence,27,32,37 and self-efficacy.30 in addition, this type of support group led to increased autonomy and well-being. one study, by richardson et al.22 examined the impact of peer support from the mentors’ perspective and found that it gave them a sense of purpose and a feeling of usefulness. additionally, wegener et al.30 measured the effect of a peer support intervention on self-efficacy and found it led to an increase in participants. the acceptance and adaptation to major limb loss were explored in two qualitative studies22,31 and one rct.29 the study by liu et al.31 reported that observing peers’ success with limb loss helped participants put their experiences into perspective. richardson et al.22 examined the impact of providing support as a peer mentor and found that this was a useful experience, as it not only increased well-being, but it aided the peer mentor in adjusting to their limb loss. the rct conducted by turner et al.29 measured satisfaction with life using the world health quality of life scale. the study found greater improvements in participants led by a licensed health professional paired with a peer support compared to the control participants that were provided with educational materials and no support from a professional or peer.29 barriers and risks in the provision of peer support six studies discussed the perceived barriers and risks to the provision of peer support. physical and organizational-level barriers one cross-sectional study exploring peer support as a primary objective discussed a physical barrier to peer support.26 participants in this study reported that the geographical distance of peer support meetings was inaccessible and inconvenient to them. perceived organizational barriers were discussed in two qualitative studies.22,26 nathan et al. 26 reported that the short duration and frequency of peer support meetings deterred participants from joining groups. while richardson et al.22 reported that participants felt there was a lack of formal training for peer mentors facilitating peer support programs, which resulted in uncertainty about the role of peers and their reputability. individual level barriers three qualitative studies discussed barriers specific to the individual.22,24,26 participant reluctance to join support groups stemmed from various factors, encompassing feelings of self-consciousness regarding involvement,24 apprehension about opening up to peers and displaying vulnerability,26 or a perception that the discussed topics did not directly address their individual needs.26 the peer mentors facilitating peer support groups also expressed feelings of doubt and uncertainty about whether their delivery of peer support was beneficial to their participants.22 two qualitative studies reported on the perceived risks of the provision of peer support.22,28 richardson et al.22 reported that peer support was physically and emotionally burdensome for peer mentors and that there was a lack of support for their well-being. mortimer et al.28 reported that the information discussed between peer mentors and mentees during informal peer support interventions can be misleading and cause distress to participants. barriers to group dynamics barriers to peer support group dynamics were discussed in four qualitative studies.24,26,35,37 participants report that peer support groups can be intimidating to engage in due to their “cliquey” environments24,26 and they can increase an individual’s negative thoughts about their amputation.35 poor leadership and a lack of commonality among group members have also been described as factors deterring amputees from wanting to engage in peer support groups.26 three studies discussed that their peer support groups were male-dominated, making it difficult for women to connect with other female amputees, and reported a lack of support available for addressing female-specific needs.26,35,37 https://doi.org/10.33137/cpoj.v6i1.42170 6 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 table 1: study details. author (year) location design study objectives type of amputation care setting sample age range (years) sex amorelli et al.21(2019) usa qualitative to examine the components of the au program through individual with amputation and healthcare professionals (hcps) experiences, and to understand the value this program brings to the limb loss community. major upper and lower limb community n = 10 (hcps) n = 7 (amputees) 17+ n = 15 (male) n = 2 (female) andersen et al.36 (2023) democratic republic of congo non-controlled retrospective cohort study to examine predictors of depression, anxiety, and stress prior to and following participation in the mental health and psychosocial support (mhpss) intervention. major upper and lower limb n/a n = 132 (total) n = 100 (amputees) 0-70 n = 93 (male) n = 39 (female) anderson et al.20 (2022) uk & australia narrative exploration study (phenomenolo gical approach) examine the experiences and perspectives of prosthetic and orthotic users and explore their needs for the future. major lower limb n/a n = 5 33-67 n = 2 (male) n = 3 (female) anderson et al.24 (2019) australia qualitative (naturalistic enquiry) to understand participant motivation to join a mobility clinic, examine their experiences, and understand its perceived benefits to their mobility. major lower limb community n = 9 25-60 n = 3 (male) n = 6 (female) brusco et al.27 (2023) australia cost analysis explore the cost, impact, and willingness to pay for an amputee peer support program; a program offered by limbs 4 life. n/a community n = 38 (hcps) n = 86 (program volunteers) n = 12 (program participants) n (mean age): 40.7 (hcps) 59.2 (program volunteers) 70.2 (program participants) hcp n = 8 (male) n = 5 (female) program volunteers n = 58 (male) n = 28 (female) program participants n = 8 (male) n = 4 (female) dillon et al.34 (2020) australia qualitative (narrative inquiry approach) to understand the experiences of individuals who have had sequential partial foot and transtibial amputations. major lower limb hospital & community n = 10 21-73 n = 8 (male) n = 2 (female) keeves et al.38 (2022) australia exploratory qualitative study to determine the factors that facilitate and impede social and community participation following traumatic lower limb amputations. major lower limb n/a n = 9 50-64 n = 7 (male) n = 2 (female) lehavot et al.37 (2022) usa national qualitative study to understand the perspectives of women veterans with lower limb loss regarding prosthetic devices and care. major lower limb n/a n = 30 40-80 n = 30 (female) liu et al.31 (2010) taiwan qualitative (phenomenolo gical approach) to explore the perspectives of taiwanese people who experienced a lower extremity amputation preand six months post-surgery. major lower limb rehabilitati on n = 22 56-84 n = 15 (male) n = 7 (female) macbride et al.25 (1980) canada qualitative to examine individual withamputation perspectives on group meetings and to understand the psychological impact of amputation and its influence on the success of amputee programs. major upper and lower limb rehabilitati on n/a 64 (median) 3:1 (male: female ratio) mackay et al.39 (2022) canada qualitative to examine the experiences of individuals in the community who have lower extremity dysvascular amputation. major lower limb n/a n = 35 72-86 n = 23 (male) n = 12 (female) https://doi.org/10.33137/cpoj.v6i1.42170 7 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 table 1 (continued): study details. mayo et al.40 (2022) canada qualitative descriptive to examine the mental health needs of individuals with lower limb amputations and understand their perspectives on using icbt as a coping strategy postamputation. major lower limb n/a n = 10 43-77 n = 9 (male) n = 1 (female) mcgill et al.41 (2021) uk qualitative explores the physical, psychological, and social experiences of veterans with limb loss and examines the factors that facilitate their independence. major upper and lower limb n/a n = 32 40-95 n = 30 (male) n = 2 (female) messinger et al.32 (2018) usa crosssectional (interpretive phenomenolog ical approach) to explore the social experiences and recovery outcomes of amputees in the military advanced training centre at walter reed national military medical centre. major lower limb rehabilitati on n = 20 25-45 n = 19 (male) n = 1 (female) mortimer et al.28 (2002) scotland qualitative examine the experiences of amputees with (1) phantom limb pain, (2) perceptions of the current information provided about phantom pain, and (3) opinions about what information should be provided. major lower limb community n = 31 30-74 n = 18 (male) n = 13 (female) nathan & winkler26 (2019) usa crosssectional survey design to explore the reasons a person with amputation will join, leave, or return to a peer support group as well as understand the role of technology-based support groups for amputees. major upper and lower limb n/a n = 54 20-82 n = 36 (male) n = 18 (female) radenovic et al.33 (2022) canada qualitative descriptive and discovery oriented approach understand the experiences of individuals with major lower limb loss and the factors that influence their reintegration into the community. major lower limb rehabilitati on n = 9 51-82 n = 7 (male) n = 2 (female) richardson et al.42 (2020) uk qualitative (interpretative phenomenolog ical analysis) to explore the experiences and perceptions of peer mentors delivering peer support interventions to lower limb amputees. major lower limb community n = 8 56-84 n = 3 (male) n = 5 (female) stutts et al.35 (2015) usa qualitative (interpretative phenomenolog ical analysis) to explore the coping strategies, perceived social support, participation in support groups, and experiences of acceptance and growth in women with amputations. major upper and lower limb n/a n = 30 23-81 n = 30 (female) turner et al.29 (2021) usa multisite, 2arm cluster rct with masked outcome assessment examine the effectiveness of the vetpals intervention on physical, psychological, and quality of life domains for individuals with lower limb loss and understand the feasibility of incorporating this program into a national health care program. major lower limb community n = 147 control = 64.12 (mean) treatment = 64.89 (mean) control n = 76 (male) treatment n = 68 (male) valizadeh et al.23 (2014) iran qualitative content analysis explores the experiences of lower limb amputees and examines the influence of support sources on their ability to adapt to their amputation. major lower limb n/a n = 20 25-57 n = 17 (male) n = 3 (female) wegener et al.30 (2009) usa rct examined the effectiveness of a community-based self-management program on health outcomes for individuals with limb loss. major upper and lower limb community n = 502 control = 56.9 (mean) treatment = 55.5 (mean) control n = 134 (male) n = 93 (female) treatment n = 151 (male) n = 124 (female) https://doi.org/10.33137/cpoj.v6i1.42170 8 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 discussion this scoping review describes the nature of the existing literature on peer support for individuals with major limb loss. based on our findings, there appears to be no clear consensus on a definition of peer support. the literature also lacked comprehensive exploration of the implementation of peer support interventions, with only a limited number of studies detailing the various settings and delivery methods employed. studies that discussed the settings of peer support gatherings mainly described them within community-based locations, and methods of delivery varied between formal and informal formats. most of the research included in this review provided evidence through participants’ perceived experiences. there were only two rcts that explored peer support as an intervention; they measured outcomes related to physical, social, psychological, and quality of life domains. the benefits of peer-support interventions were highlighted in all articles, which included physical or psychosocial benefits. conversely, there were few articles examining the barriers to peer support, which included organizational, individual, and group dynamic barriers. limited studies defined peer support, but the prevailing agreement among these studies was that peer support involves the sharing of experiences among individuals with major limb loss.21-24,26 the lack of clarity in defining peer support for major limb loss resonates with similar observations across other healthcare contexts.43,44 the inconsistency in definitions might be attributed to the diverse nature of peer support interventions and the contextual variations in their implementation. comparable challenges in defining peer support have been identified in studies focusing on peer support for mental health and chronic disease populations.43,44 this may be due to the more recent introduction of peer support as an integral part of the healthcare system. this discrepancy underscores the need for standardized terminology to facilitate effective communication and comprehension among researchers, practitioners, and participants. peer support groups were positively reported by all studies included in this scoping review. the perceived benefit with the greatest amount of evidence was social support and connectedness. this was achieved through sharing experiences and giving or receiving advice from other group members.22 in a previous integrated review, reichmann et al.45 similarly identified that peer support interventions benefited psychosocial outcomes during rehabilitation. the unique value of peer support provides participants with the opportunity to obtain reassurance from others in a similar position as themselves.34 for instance, peers with major limb losses reported that they were able to provide others with feelings of optimism and hope for the future.21 similar claims were reported in peer support studies for individuals with diabetes, stating that sharing experiences enabled participants to receive validation from others when expressing their frustrations and concerns about their diabetes management.46 significant emphasis on knowledge exchange and education facilitated in peer support groups was also positively highlighted throughout the review.21,24-28,34,35,37,40 according to wasilewski et al.16 this is attributed to participants finding educational information more informative and engaging when delivered by a peer, as they were able to resonate better due to shared experiences. in addition, peer support led to the building of friendships and a community for individuals with major limb loss.20,22,24,31,39-41 peers were able to share advice amongst each other, which inspired them to engage more in the community, in daily activities, and build a life outside their family and non-amputee friends.16,42,47 in this review, findings suggest participants expressed concerns regarding inaccessibility (e.g., geographical distance) and the inconvenience of attending peer support meetings.26,48 flexible communication options, like telephone or online platforms, have been proposed as solutions and proven effective in increasing attendance frequency and participation.20,39,46 a meta-analysis of patients with diabetes found that support groups offered through telephone-based communications were equally effective as in person.16 additionally, barriers to participation or engagement occurred due to a lack of peer mentor training, which resulted in poor leadership skills and selfdoubt among participants and mentors.22,26 the review underscores the potential benefits of peer support, particularly in terms of social support, connectedness, knowledge exchange, and communitybuilding. however, research on the effectiveness of peer support interventions from rcts is limited. moreover, this research highlighted challenges to participation and engagement, such as accessibility and group dynamics. future research should focus on developing and evaluating flexible communication options, like online platforms, to overcome geographical barriers. additionally, comprehensive mentor training, mentor-mentee relationship-building, and tailored group categorization should be further explored to enhance engagement and address dynamics within peer support groups. strengths and limitations the strength of this scoping review is in the methodological rigour of the approach. this review followed arksey and o’malley’s methodological framework and was guided by a university-affiliated scientific librarian. as a result, this review provides a comprehensive summary of existing literature on the topic of peer support specific to individuals with amputations. this scoping review had some limitations. first, most of the articles included in this study did not explore peer support as their primary objective. this and the lack of rcts made it difficult for the authors to understand the direct impact of peer support on health outcomes, as https://doi.org/10.33137/cpoj.v6i1.42170 9 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 most studies only focused on its perceived benefits. this limited our study objective to understanding the impact of peer support as an intervention. conclusion this scoping review provided an understanding of what is known in the literature about peer support and people with major limb amputations. for this population, studies have shown that there are many perceived benefits to the provision of peer support. however, given the small number of studies in this field, future research is needed to explore the implementation process and evaluate the effectiveness of peer support for this population. acknowledgements the authors of this article would like to express appreciation to katie merriman (academic librarian at the university of toronto), for her assistance with the development of the literature search strategy. declaration of conflicting interests the authors report that there are no conflicts of interest to declare. authors contribution • annamaria costa-parke: responsible for researching and reviewing all included articles and co-writing manuscript. • anna maria di lella: responsible for researching and reviewing all included articles and co-writing manuscript. • ashley walker: responsible for editing and co-writing manuscript. • lee verweel: conceptualizing project, responsible for editing, co-writing manuscript, project supervision. • crystal mackay: conceptualizing project, responsible for editing, co-writing manuscript, project supervision. sources of support no funding was provided for this review. references 1.mulindwa b, nalwoga rp, nakandi bt, mwaka es, kenney lpj, ackers l, et al. evaluation of the current status of prosthetic rehabilitation services for major limb loss: a descriptive study in ugandan referral hospitals. disabil rehabil. 2023;1–10. doi: 10.1080/09638288.2023.2188266 2.jo s-h, kang s-h, seo w-s, koo b-h, kim h-g, yun s-h. psychiatric understanding and treatment of patients with amputations. yeungnam univ j med. 2021;38(3):194–201. doi: 10.12701/yujm.2021.00990 3.caddick n, cullen h, clarke a, fossey m, hill m, mcgill g, 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technol. 2019;13(3):493–497. doi: 10.1177/1932296818818828 47.magasi s, papadimitriou c. peer support interventions in physical medicine and rehabilitation: a framework to advance the field. arch phys med rehabil. 2022;103(7). doi: 10.1016/j.apmr. 2020.09.400 48.matthias ms, kukla m, mcguire ab, damush tm, gill n, bair mj. facilitators and barriers to participation in a peer support intervention for veterans with chronic pain. clin j pain. 2016;32(6):534–540. doi: 10.1097/ajp.0000000000000297 https://doi.org/10.33137/cpoj.v6i1.42170 11 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 appendicies legend appendix a: ovid medline (timeline: 1946 to 2023) operator meaning .tw title or abstract .kf word in author provided keyword .tw,kf the term is found in the title, abstract or in an author provided keyword * or $ truncation (e.g., support or supports or supporting) or/#-# refers to the lines that include words related to the search term (eg. or/1-10 [amputation] means that lines 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 include terms related to amputation) adj# the search term is within a specified number of words of the term (e.g. peer adj2 is within 2 words of the term support* (e.g., peer support or supporting a peer)) # searches results 1 amputation/ or disarticulation/ or hemipelvectomy/ 23917 2 amputation, traumatic/ or leg amputation/ or above knee amputation/ or below knee amputation/ or knee amputation/ or arm amputation/ or amputation/ or foot amputation/ or hand amputation/ or limb amputation/ 27952 3 (major limb amputat* or major limb loss or limb absence or limb loss).tw,kf. 2524 4 (lower limb amputation* or upper limb amputation*).tw,kf. 2801 5 amputation stumps/ 3218 6 amputation, surgical/ 182 7 artificial limbs.tw,kf. 587 8 amputat* stump*.tw,kf. 1095 9 artificial limbs/ 7930 10 ((leg or knee or arm or foot or hand or wrist or ankle or limb) adj3 amputat*).tw,kf. 12980 11 or/1-10 [amputation] 42690 12 social support/ 78053 13 (peer adj2 (group* or support* or coach* or mentor*)).tw,kf. 13117 14 peer group/ 23804 15 mentoring/ 3699 16 (social adj2 support).tw,kf. 54253 17 (lay$ adj2 (led or run or help$ or support$ or visit$ or based or deliver$ or worker? or person$)).tw,kf. 8855 18 (user$ adj2 (led or run or help$ or support$ or visit$ or based or deliver$)).tw,kf. 7513 19 (voluntary adj2 (work$ or care or involvement or help$ or counsel$)).tw,kf. 2660 20 (volunteer adj2 (work$ or care or involvement or help$ or counsel$)).tw,kf. 1240 21 (community adj2 (person$ or based or visit$ or worker?)).tw,kf. 88377 22 (support adj2 (person$ or worker?)).tw,kf. 7020 23 (mutual adj2 (aid or support?)).tw,kf. 1512 24 (expert adj2 patient?).tw,kf. 1268 25 (non adj2 (professional? or medical)).tw,kf. 12426 26 (supportive adj2 relationship).tw,kf. 310 27 (health adj2 coach$).tw,kf. 1438 28 peer* to peer* support.tw,kf. 200 29 patient* to patient* support.tw,kf. 29 30 survivor* network*.tw,kf. 51 31 or/12-30 [peer support] 260846 32 11 and 31 300 https://doi.org/10.33137/cpoj.v6i1.42170 12 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 appendix b: embase (timeline: 1947 to 2023) # searches results 1 amputation/ or disarticulation/ or hemipelvectomy/ 35000 2 amputation, traumatic/ or leg amputation/ or above knee amputation/ or below knee amputation/ or knee amputation/ or arm amputation/ or amputation/ or foot amputation/ or hand amputation/ or limb amputation/ 59817 3 (major limb amputat* or major limb loss or limb absence or limb loss).tw,kf. 3357 4 (lower limb amputation* or upper limb amputation*).tw,kf. 3860 5 amputation stumps/ 7003 6 amputation, surgical/ 0 7 artificial limbs.tw,kf. 594 8 amputat* stump*.tw,kf. 1193 9 artificial limbs/ 4445 10 ((leg or knee or arm or foot or hand or wrist or ankle or limb) adj3 amputat*).tw,kf. 18335 11 or/1-10 [amputation] 73823 12 social support/ 109599 13 (peer adj2 (group* or support* or coach* or mentor*)).tw,kf. 17481 14 peer group/ 29351 15 mentoring/ 6087 16 (social adj2 support).tw,kf. 66633 17 (lay$ adj2 (led or run or help$ or support$ or visit$ or based or deliver$ or worker? or person$)).tw,kf. 9821 18 (user$ adj2 (led or run or help$ or support$ or visit$ or based or deliver$)).tw,kf. 9109 19 (voluntary adj2 (work$ or care or involvement or help$ or counsel$)).tw,kf. 3125 20 (volunteer adj2 (work$ or care or involvement or help$ or counsel$)).tw,kf. 1615 21 (community adj2 (person$ or based or visit$ or worker?)).tw,kf. 111367 22 (support adj2 (person$ or worker?)).tw,kf. 9212 23 (mutual adj2 (aid or support?)).tw,kf. 1877 24 (expert adj2 patient?).tw,kf. 2312 25 (non adj2 (professional? or medical)).tw,kf. 19072 26 (supportive adj2 relationship).tw,kf. 406 27 (health adj2 coach$).tw,kf. 2084 28 peer* to peer* support.tw,kf. 328 29 patient* to patient* support.tw,kf. 51 30 survivor* network*.tw,kf. 78 31 or/12-30 [peer support] 322841 32 11 and 31 514 https://doi.org/10.33137/cpoj.v6i1.42170 13 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 appendix c: psycinfo (timeline: 1806 to 2023) # searches results 1 amputation/ or disarticulation/ or hemipelvectomy/ 1109 2 "amputation, traumatic"/ or "leg amputation"/ or "above knee amputation"/ or "below knee amputation"/ or "knee amputation"/ or "arm amputation"/ or amputation/ or "foot amputation"/ or "hand amputation"/ or "limb amputation"/ 1109 3 ("major limb amputat*" or "major limb loss" or "limb absence" or "limb loss").ti,ab,id. 154 4 ("lower limb amputation*" or "upper limb amputation*").ti,ab,id. 251 5 "amputation stumps"/ 0 6 "amputation, surgical"/ 0 7 "artificial limbs".ti,ab,id. 41 8 "amputat* stump*".ti,ab,id. 22 9 "artificial limbs"/ 1121 10 ((leg or knee or arm or foot or hand or wrist or ankle or limb) adj3 amputat*).ti,ab,id. 762 11 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 [amputation] 2387 12 "social support"/ 42141 13 (peer adj2 (group* or support* or coach* or mentor*)).ti,ab,id. 15696 14 "peer group"/ 0 15 mentoring/ 0 16 (social adj2 support).ti,ab,id. 61395 17 (lay# adj2 (led or run or help# or support# or visit# or based or deliver# or worker? or person#)).ti,ab,id. 4 18 (user# adj2 (led or run or help# or support# or visit# or based or deliver#)).ti,ab,id. 850 19 (voluntary adj2 (work# or care or involvement or help# or counsel#)).ti,ab,id. 228 20 (volunteer adj2 (work# or care or involvement or help# or counsel#)).ti,ab,id. 208 21 (community adj2 (person# or based or visit# or worker?)).ti,ab,id. 38917 22 (support adj2 (person# or worker?)).ti,ab,id. 2600 23 (mutual adj2 (aid or support?)).ti,ab,id. 1911 24 (expert adj2 patient?).ti,ab,id. 260 25 (non adj2 (professional? or medical)).ti,ab,id. 4077 26 (supportive adj2 relationship).ti,ab,id. 528 27 (health adj2 coach#).ti,ab,id. 2 28 "peer* to peer* support".ti,ab,id. 115 29 "patient* to patient* support".ti,ab,id. 7 30 "survivor* network*".ti,ab,id. 30 31 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or "30 [peer support]".mp. [mp=title, abstract, heading word, table of contents, key concepts, original title, tests & measures, mesh word] 132455 32 11 and 31 82 https://doi.org/10.33137/cpoj.v6i1.42170 14 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 appendix d: cinahl (timeline: 1991 to 2023) appendix d: cinahl (timeline: 1991 to 2023) # query limiters/ expanders last run via results s32 s11 and s31 search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 187 s31 s12 or s13 or s14 or s15 or s16 or s17 or s18 or s19 or s20 or s21 or s22 or s23 or s24 or s25 or s26 or s27 or s28 or s29 or s30 search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 131,387 s30 (ti "survivor* network*" or ab "survivor* network*" or su "survivor* network*") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 34 s29 (ti "patient* to patient* support" or ab "patient* to patient* support" or su "patient* to patient* support") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 1 s28 (ti "peer* to peer* support" or ab "peer* to peer* support" or su "peer* to peer* support") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 106 s27 ((ti health or ab health or su health) n2 (ti coach? or ab coach? or su coach?)) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 461 s26 ((ti supportive or ab supportive or su supportive) n2 (ti relationship or ab relationship or su relationship)) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 1,276 s25 ((ti non or ab non or su non) n2 ((ti professional# or ab professional# or su professional#) or (ti medical or ab medical or su medical))) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 6,442 s24 ((ti expert or ab expert or su expert) n2 (ti patient# or ab patient# or su patient#)) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 1,843 s23 ((ti mutual or ab mutual or su mutual) n2 ((ti aid or ab aid or su aid) or (ti support# or ab support# or su support#))) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 1,175 s22 ((ti support or ab support or su support) n2 ((ti person? or ab person? or su person?) or (ti worker# or ab worker# or su worker#))) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 5,168 https://doi.org/10.33137/cpoj.v6i1.42170 15 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 appendix d (continued): cinahl (timeline: 1991 to 2023) s21 ((ti community or ab community or su community) n2 ((ti person? or ab person? or su person?) or (ti based or ab based or su based) or (ti visit? or ab visit? or su visit?) or (ti worker# or ab worker# or su worker#))) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 53,178 s20 ((ti volunteer or ab volunteer or su volunteer) n2 ((ti work? or ab work? or su work?) or (ti care or ab care or su care) or (ti involvement or ab involvement or su involvement) or (ti help? or ab help? or su help?) or (ti counsel? or ab counsel? or su counsel?))) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 1,411 s19 ((ti voluntary or ab voluntary or su voluntary) n2 ((ti work? or ab work? or su work?) or (ti care or ab care or su care) or (ti involvement or ab involvement or su involvement) or (ti help? or ab help? or su help?) or (ti counsel? or ab counsel? or su counsel?))) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 655 s18 ((ti user? or ab user? or su user?) n2 ((ti led or ab led or su led) or (ti run or ab run or su run) or (ti help? or ab help? or su help?) or (ti support? or ab support? or su support?) or (ti visit? or ab visit? or su visit?) or (ti based or ab based or su based) or (ti deliver? or ab deliver? or su deliver?))) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 3,951 s17 ((ti lay? or ab lay? or su lay?) n2 ((ti led or ab led or su led) or (ti run or ab run or su run) or (ti help? or ab help? or su help?) or (ti support? or ab support? or su support?) or (ti visit? or ab visit? or su visit?) or (ti based or ab based or su based) or (ti deliver? or ab deliver? or su deliver?) or (ti worker# or ab worker# or su worker#) or (ti person? or ab person? or su person?))) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 1,128 s16 ((ti social or ab social or su social) n2 (ti support or ab support or su support)) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 38,938 s15 (mh mentoring) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 0 s14 (mh "peer group") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 15,928 s13 ((ti peer or ab peer or su peer) n2 ((ti group* or ab group* or su group*) or (ti support* or ab support* or su support*) or (ti coach* or ab coach* or su coach*) or (ti mentor* or ab mentor* or su mentor*))) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 23,113 s12 (mh "social support") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 0 s11 s1 or s2 or s3 or s4 or s5 or s6 or s7 or s8 or s9 or s10 search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 12,972 s10 (((ti leg or ab leg or su leg) or (ti knee or ab knee or su knee) or (ti arm or ab arm or su arm) or (ti foot or ab foot or su foot) or (ti hand or ab hand or su hand) or (ti wrist or ab wrist or su wrist) or (ti ankle or ab ankle or su ankle) or (ti limb or ab limb or su limb)) n3 (ti amputat* or ab amputat* or su amputat*)) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 6,306 https://doi.org/10.33137/cpoj.v6i1.42170 16 costa-parke a, di lella a.m, walker a, verweel l, mackay c. peer support for individuals with major limb loss: a scoping review. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.6. https://doi.org/10.33137/cpoj.v6i1.42170 canadian prosthetics & orthotics journal issn: 2561-987x peer support for individuals with major limb loss costa-parke et al., 2023 appendix d (continued): cinahl (timeline: 1991 to 2023) s9 (mh "artificial limbs") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 0 s8 (ti "amputat* stump*" or ab "amputat* stump*" or su "amputat* stump*") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 553 s7 (ti "artificial limbs" or ab "artificial limbs" or su "artificial limbs") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 56 s6 (mh "amputation, surgical") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 0 s5 (mh "amputation stumps") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 498 s4 ((ti "lower limb amputation*" or ab "lower limb amputation*" or su "lower limb amputation*") or (ti "upper limb amputation*" or ab "upper limb amputation*" or su "upper limb amputation*")) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 1,480 s3 ((ti "major limb amputat*" or ab "major limb amputat*" or su "major limb amputat*") or (ti "major limb loss" or ab "major limb loss" or su "major limb loss") or (ti "limb absence" or ab "limb absence" or su "limb absence") or (ti "limb loss" or ab "limb loss" or su "limb loss")) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 1,010 s2 (mh "amputation, traumatic") or (mh "leg amputation") or (mh "above knee amputation") or (mh "below knee amputation") or (mh "knee amputation") or (mh "arm amputation") or (mh amputation) or (mh "foot amputation") or (mh "hand amputation") or (mh "limb amputation") search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 8,309 s1 (mh amputation) or (mh disarticulation) or (mh hemipelvectomy) search modes boolean/phrase interface ebscohost research databases search screen advanced search database cinahl 7,738 https://doi.org/10.33137/cpoj.v6i1.42170 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 6, issue 1 2023 research article khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v6i1.41454 1 khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 research article reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation khani a1, babaee t2 *, khaghani a2, nakhaee m3, fatahi z1, moss t4 1 department of orthotics and prosthetics, university of social welfare and rehabilitation sciences, tehran, iran. 2 rehabilitation research center, department of orthotics and prosthetics, school of rehabilitation sciences, iran university of medical sciences, tehran, iran. 3 department of rehabilitation, faculty of allied medicine, kerman university of medical sciences, kerman, iran. 4 centre for appearance research, university of the west of england, bristol, uk. introduction disfigurement can be defined as a visible difference or unusual appearance as a result of a mark, rash, scar, or graft on a person’s skin or an asymmetry or paralysis to a person’s face or body.1 disfigurement might occur due to congenital malformation, traumatic events, and disease processes.2 traumatic amputation, amputation due to diabetes mellitus and burn injuries are among the leading causes of disfigurement in low to middle-income countries.3,4 despite the recent advancements in the design and manufacture of prostheses to improve their natural size, shape, and movement, prosthesis users may become selfconscious about their appearance.5 this is partly due to the judgment and stigma they experience in their daily life.6 the extent to which the disfigurement affects one’s perception of his/her appearance depends on two main factors.7 the first factor which is mainly social and cultural, which include social cues and feedback one might get from others. disfigured individuals are usually less involved in social activities and tend to be isolated from society. the second factor is the individual’s self-perception determined by the impact of appearance on one’s perception of selfconcept, emotional well-being, and quality of life. being open access abstract background: despite the recent advancements in the design and manufacture of prostheses for individuals with craniofacial irregularity and amputation, these individuals tend to become self-conscious about their appearance. the aim of this study was to investigate the reliability and validity of persian version of the derriford appearance scale24 (p-das24) for a sample of individuals with craniofacial irregularity and limb loss. methodology: reliability of the p-das24 was determined by computing internal consistency and testretest reliability utilizing cronbach’s alpha coefficient and pearson’s correlation coefficient. discriminant validity was investigated with comparing the total score of the p-das24 between disfigured participants and those with no appearance problem. known-groups validity was evaluated regarding the participants’ gender and their level of involvement. findings: the sample size comprised of 251 individuals with disfigurement and 101 without disfigurement who were deemed normal in appearance. the p-das24 showed satisfactory internal consistency (cronbach’s alpha = 0.89) and excellent test-retest reliability (r = 0.96). the total score of the p-das24 showed a statistically significant difference between individuals deemed disfigured or normal (p=0.01). the total scores p-das24 in individuals with different levels of involvement were significantly different (p<0.001). the scores of the das2, das18, das21, and das24 were significantly different between men and women (p<0.01, <0.01, 0.03, and 0.01, respectively). conclusion: the p-das24 is a valid and reliable tool that may be utilized in clinical practice and researches to assess the outcomes of prosthetic reconstructions in individuals with disfigurement. article info received: august 22, 2023 accepted: november 10, 2023 published: november 24, 2023 citation khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i 1.41454 keywords appearance, disfigurement, craniofacial defect, amputation, prosthesis, rehabilitation * corresponding author: taher babaee, phd, rehabilitation research center, department of orthotics and prosthetics, school of rehabilitation sciences, iran university of medical sciences, tehran, iran. email: babaee.t@iums.ac.ir orcid id: https://orcid.org/0000-0002-1487-2374 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 1, article no.3. 2023 https://doi.org/10.33137/cpoj.v6i1.41454 https://doi.org/10.33137/cpoj.v6i1.41454 https://doi.org/10.33137/cpoj.v6i1.41454 mailto:babaee.t@iums.ac.ir https://orcid.org/0000-0002-1487-2374 https://jps.library.utoronto.ca/index.php/cpoj/index 2 khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 canadian prosthetics & orthotics journal issn: 2561-987x the persian version of the derriford appearance scale 24 khani et al., 2023 different from others might lead to feelings of shame, lower self-esteem, and appearance consciousness.7,8 facially or physically disfigured individuals encounter more psychosocial problems in their daily lives than individuals deemed attractive.9 social stereotypes have led to the general assumption that physically attractive adults have more socially appealing personalities and live more fulfilling lives than those of lesser attractiveness.10 furthermore, they receive more attention and social support in childhood and adulthood.11 on the other hand, disfigured individuals experience anxiety, discomfort, and alienation from other members of society.12 psychological adjustment to the injury and disfigurement is a challenging phase when returning to society7 as social discomfort and body image anxiety is relatively higher in some people with amputation than individuals without amputation.13 based on data of a study published in 2021, a total of 57.7 million people were living with limb loss globally.14 therefore, it is of paramount importance for the therapist/clinician to understand the psychosocial factors affecting one’s adaptation process to disfigurement/ amputation to adopt the most effective therapeutic approach and navigate a better restoration of body identity.15 various psychometric tools have been developed to assess the psychological impact and adjustment of appearances such as the appearance schemas inventory,15 the body image avoidance questionnaire,16 and the body dysmorphic disorder examination.17 these questionnaires lack the necessary sensitivity to the nature of the irregularity and were not specifically designed to fully cover the spectrum of symptoms relevant to the wide range of difficulties experienced by individuals with disfigurement.12 given the complexity of how an appearance difference might affect one’s social interaction and the resulting distress, the measure for this assessment should be well-standardized and psychometrically robust in order to fully capture the distress and dysfunction arising from body-image disturbance.18 the derriford appearance scale (das) is a valid and factorial scale that examines the psychosocial adjustment issues of subjects with a visible difference.18 this questionnaire examines the negative emotions of people with facial problems (such as fear, social anxiety, and shyness) and negative behaviors such as isolationism that may affect their lifestyle.19 das is available in two versions: das59 and the short form of das24. das24 specifically assesses appearance-related distress and dysfunction. in a study of 525 individuals with appearance problems, the das24 total score showed excellent internal consistency and concurrent validity with the das59.19 the das24 questionnaire is suitable for patients on the plastic surgery list, people with cutaneous acne, neurofibromatosis, and eczema and it has formerly been used in a wide range of individuals who had appearance-related issues in different parts of their body.20 the questionnaire has also been widely used to assess general population facial concerns.20 although the persian version of das59 was made available by sadeghi-bazargani et al.,9 the lengthy nature of the das59 has made its use time-consuming. routine data collection in clinical practice and measurement of distress when there is a severe lack of time necessitates validation of its short form with the same sensitivity and improved time efficiency. the robust nature of das24 has made this questionnaire a more user-friendly and brief instrument for clinicians to evaluate the therapeutic outcome of the treatment process of individuals with disfigurement.17 the das24 has so far been translated into taiwanese,21 brazilian/portuguese22 and italian.23 it should be noted that both versions of das59 and das24 are available in italian language.23,24 given the ethnic, linguistic, and cultural differences between different communities that can influence how patient-centered questionnaires are completed, it is necessary to conceptually translate and validate the text of the questionnaire and confirm its reliability and validity to use scales such as das24. also, in order to improve the generalizability and proper use of this instrument for individuals using cosmetic or functional prosthesis, this study was aimed at providing the persian version of the das24 for a sample of individuals with craniofacial irregularity and limb loss. methodology translation and cultural adaptation the process of cultural adaptation of the das24 was conducted using the guidelines introduced by beaton et al.25 there were five main stages of forward translation, synthesizing of translations, backward translation, expert committee revision and the pre-final trial run (figure 1). prior to initiation of the study, permission to translate and culturally adapt the das24 was obtained from the developer via email. the study protocol was approved by the research ethics committee of kerman university of medical sciences (ref: # ir.kmu.rec.1399.413, date: 27/07/1399). the final persian version of the das24 is available as a supplementary file. participants and sampling a convenience sample of 352 participants were enrolled in this study. 251 of whom had a disfigurement at some level and 101 individuals were normal and not visibly different. the disfigurement group had a discernible difference either in their appearance or daily function with the prosthesis. the inclusion criteria for the disfigurement group included: 1) being 18 or older, 2) having had facial amputation or limb loss with detectable dissimilarity, 3) having used a prosthesis for at least 3 months, 4) being able to read and write in persian. https://doi.org/10.33137/cpoj.v6i1.41454 3 khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 canadian prosthetics & orthotics journal issn: 2561-987x the persian version of the derriford appearance scale 24 khani et al., 2023 the research was conducted in two orthotics and prosthetics clinics which were referral centers for patients from all over iran. data collection was carried out from november 2021 to august 2022. the sample included those who had lost their body parts due to trauma (accidents, war), cancer, diabetes, burn, vascular disease or the cause of their disfigurement was congenital. the survey was filled either in person or online. before filling in the questionnaire, subjects were provided a consent form to sign. for the online version, an invitation message was sent via whatsapp which included a brief description of the study and a link to the questionnaire. consent was obtained through the inclusion of a statement embedded at the beginning of the online survey. the phone number of the respondents were automatically removed by the software used (https://porsline.ir). the participants remained anonymous through the statistical analyses. the derriford appearance scale 24 the das24 is a twenty-four-item instrument aimed to assess the anxiety and impairments that results from abnormalities in one’s appearance.26 the first page of the scale consists of two parts. the upper section includes the demographic information, and the lower section determines the body part(s) that has disturbed the participants’ appearance. the primary section of the questionnaire includes 24 items. some of the items are presented with 4 and some are presented with 5 responses. for items a, b, d, h, j, n, q, t, and v the scores range from 1 (minimum discomfort) to 4 (maximum discomfort). the remaining 14 items are given scores from 0 (not applicable) to 4 (maximum discomfort). thus, the minimum score for a respondent in das24 is 11 and the maximum is 96. the greater the score, the more self-conscious one feels about his/her appearance. data analyses reliability reliability of the persian version of das24 (p-das24) were assessed by computing internal consistency and also testretest reliability. internal consistency or homogeneity of a scale represent the relationship between the score of each individual item and the total score.27 test-retest reliability is to assess the reproducibility of the same scores for a scale over repeated trials. to investigate the test-retest reliability of the p-das24, a sample of 39 participants (19 cases with transtibial amputation, 9 with transfemoral amputation, 7 with craniofacial irregularity, 3 with syme disarticulation, and 1 with knee disarticulation) were randomly asked to complete the scale once again with the time interval of 2 weeks. for internal consistency assessment of the pdas24, cronbach's alpha coefficient was used. satisfactory internal consistency is determined by a value of 0.70 ≤ alpha ≤ 0.95 for cronbach’s alpha.28 to investigate the relationship between respective item of the p-das24 with the entire scale, the values of “corrected item-total correlation” was evaluated. the value of higher than 0.3 was deemed that each item has an agreeable relationship with the entire questionnaire.28 “cronbach’s alpha if item deleted” was run to verify whether the extent of the cronbach’s alpha increased since eliminating one item of the questionnaire. to assess the test retest reliability, the pearson correlation coefficient analysis was used. discriminant validity discriminant validity is known as the ability of an instrument to differentiate between individuals with disfigurement and figure 1: the cultural adaptation process of the persian-das24. forward translation two native persian-speaking interpreters who were fluent in english translated the original english version of the das24 into persian. synthesis of translations the two interpreters compared the two persian versions and reached a final forward translated draft of the questionnaire backward translation the translated version of the questionnaire was then translated to english by two native english-speaking interpreters who were fluent in persian. the two versions were compared and any discrepancy was resolved via discussion. the back-translated version of the questionnaire was also approved by the developer of the das24. expert committee review the translated english version of the das24 and the original version were compared to find a semantic, idiomatic, experiential, and conceptual equivalence between the persian and the original versions of the das24. having compared the questionnaires and resolved the discrepanciess, the persian version of das24 was obtained for the trial run. testing the pre-final version the comprehensibility of the persian-das24 was assessed by asking 30 participants to complete the scale and report any confusion in the provided items. the confusing items were then revised to enhance the understandability of the questionnaire for community-dwelling individuals. https://doi.org/10.33137/cpoj.v6i1.41454 4 khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 canadian prosthetics & orthotics journal issn: 2561-987x the persian version of the derriford appearance scale 24 khani et al., 2023 the normal participants.27 in this study, discriminant validity of p-das24 was assessed by conducting a comparison of the p-das24 total score between disfigured participants and those with no appearance problem using mannwhitney u test. known-groups validity in this technique, an instrument is deemed valid if it shows different scores for groups which are known to have different characteristics.27 we assessed the known-groups validity of the p-das24 regarding the gender of participants and their level of involvement (maxillofacial, upper limb amputation, transtibial amputation, knee disarticulation, transfemoral amputation, and partial foot amputation/ankle disarticulation using kruskal-wallis analysis of variance. previous studies have shown that the gender and site of involvement affects individual’s response to the das24 questionnaire.19,21,22 for the purpose of this study and to gain more reliable statistical results, individuals with involvements at eye, ear, nose and jaw were grouped as maxillofacial. also, the amputees with partial foot and rearfoot amputations were grouped as partial foot amputation/ ankle disarticulation. moreover, those with transtibial amputation, knee disarticulation, and transfemoral amputation were categorized in their own group. descriptive statistical information was reported by mean and standard deviation (sd). the relationship between the p-das24 total score and time since amputation and time using prosthesis was investigated using spearman correlation coefficient. a threshold of 0.05 was considered as the statistical significance level with 95% confidence intervals for all correlation coefficients. all statistical analysis was conducted using the spss software program version 24 (spss inc., usa). results participants the sample size comprised of 251 individuals with disfigurement and 101 without disfigurement who were deemed normal in appearance. the average age of the participants was 38.49 years old. of the disfigured individuals, 201 (80%) were men. warrelated traumatic amputation and accidents were the leading causes of disfigurement accounting for 37.8% and 35.1% of the disfigured population. participants’ level of disfigurement was seen at different levels with transtibial amputation (44.2%) being the first followed by transfemoral amputation (18%), maxillofacial irregularities (11.9%), syme amputation (11.5%), upper limb amputation (10%) and knee disarticulation (4.4%). the demographics of participants is revealed in (table 1). table 1: demographic and clinical characteristics of the studied population (n=251). n (%) variables cause of problem 16 (6.4) diabetes 88 (35.1) accidents 95 (37.8) war-related traumatic amputation 11 (4.4) cancer 18 (7.2) congenital 23 (9.2) burn level of appearance problem 30 (11.9) maxillofacial 25 (10.0) upper limb amputation 45 (18.0) transfemoral 11 (4.4) knee disarticulation 111 (44.2) transtibial 29 (11.5) partial foot and ankle amputation occupational status 191 (76.1) working 21 (8.3) unemployed 6 (2.4) student 28 (11.1) homemaker 5 (2.0) missing family status 177 (70.5) married 34 (13.5) living with relatives 37 (14.7) living alone 3 (1.2) missing educational status 50 (19.9) high school 99 (39.4) diploma 56 (22.3) bachelor 34 (13.5) master 10 (4.0) phd 2 (0.8) missing reliability the p-das24 demonstrated excellent internal consistency (cronbach’s alpha = 0.89). regarding corrected item-total correlation, our results showed that items das8, das10, and das15 had a value < 0.3. still, the cronbach’s alpha if item deleted was exceeding 0.7 for the whole p-das24. cronbach’s alpha if item deleted and corrected item total correlation scores confirmed that removing an item will not improve the value of cronbach’s alpha, therefore all of the items were maintained (table 2). the scale total score of the p-das24 showed excellent test-retest reliability (r=0.96) (table 2). discriminant validity the total score of the p-das24 showed a statistically significant difference between individuals deemed disfigured or normal (p=0.01). however, scores of items das2, das3, das5, das9, das10, das11, das13, das14, das15, das18, das21, das23, das24 did not appear to have a significant difference between the two groups (p>0.05, 0.55, 0.10, 0.97, 0.06, 0.44, 0.64 0.08, 0.57, 0.14, 0.25, 0.65, 0.35, respectively) (table 3). https://doi.org/10.33137/cpoj.v6i1.41454 5 khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 canadian prosthetics & orthotics journal issn: 2561-987x the persian version of the derriford appearance scale 24 khani et al., 2023 known-groups validity the total scores of das24 for individuals with different levels of involvement were significantly different (p<0.001). also, the scores of each item in p-das24 were shown to be significantly different with regard to the level of involvement except for das8 and das15 (p>0.89 and >0.60, respectively). although the total score did not indicate a statistically significant difference regarding the gender of the individuals (p=0.67), the scores of the das2, das18, das21, and das24 were significantly different between men and women (p<0.01, <0.01, 0.03, and 0.01, respectively) (table 3). the results of spearman correlation coefficient analysis revealed no statistically significant relationship between time since amputation, time using prosthesis and das total score (p>0.05). discussion this study was set out to validate and cross-culturally adapt the persian translated version of the das24 in a sample of individuals with upper and lower limb amputations and maxillofacial irregularities. overall, the p-das24 demonstrated satisfactory reliability. therefore, the pdas24 is a valid and reliable tool for the clinical evaluation of the appearance-related distress, anxiety and selfconsciousness experienced by individuals with visual difference on a daily basis in persian speaking countries. the das24 is a unidimensional scale extracted from the das59 which generates a full-scale score in five factorial subscales of general self-consciousness of appearance, social self-consciousness of appearance, negative selfconcept, sexual and bodily self-consciousness of appearance and facial self-consciousness of appearance.11,19 the total score of the p-das24 showed acceptable internal consistency as reflected by the cronbach’s alpha which was 0.89. this was similar to the internal consistency of the original english version,19 the brazilian/portuguese,22 and the italian version23 of the das24 (cronbach’s alpha= 0.92, 0.94, 0.93, respectively). our results were similar to that of the persian das59 which revealed excellent internal consistency (cronbach’s alpha = 0.93).9 in that study, participants had suffered a burn injury in the face, head, ear, neck, hand and legs, however, the individuals in our study had disfigurements due to amputation. regarding the itemtotal correlation, the statistical analysis revealed that items 8, 10, and 15 of the p-das24 were less than the cut-off value of 0.3. however, as confirmed by the results of cronbach’s alpha if items are deleted, all p-das24 items were associated with the entire scale (cronbach’s alpha > 0.7). table 2: descriptive statistics and results of the reliability analyses: test-retest reliability (n=39) and internal consistency (n=251). abbreviations: das = derriford appearance scale; sd = standard deviation. das24 items mean (sd) corrected item-total correlation cronbach’s alpha if item deleted pearson’s correlation coefficient for test-retest reliability das1 1.77 (0.84) 0.50 0.73 0.90 (0.82-0.94) das2 1.90 (1.08) 0.63 0.73 0.99 (0.98-0.99) das3 1.04 (1.05) 0.65 0.73 0.91 (0.84-0.95) das4 2.99 (1.04) 0.51 0.73 0.93 (0.87-0.96) das5 1.24 (1.15) 0.65 0.73 0.93 (0.87-0.96) das6 1.76 (1.44) 0.50 0.73 0.97 (0.95-0.98) das7 1.57 (1.17) 0.43 0.73 0.94 (0.89-0.96) das8 2.21 (1.23) 0.19 0.74 0.88 (0.79-0.94) das9 1.07 (1.08) 0.63 0.73 0.90 (0.82-0.95) das10 2.53 (0.96) 0.19 0.74 0.86 (0.75-0.92) das11 1.30 (0.64) 0.34 0.74 0.88 (0.78-0.93) das12 1.76 (1.41) 0.59 0.72 0.94 (0.89-0.97) das13 1.12 (0.98) 0.48 0.73 0.98 (0.96-0.99) das14 1.43 (0.80) 0.59 0.73 0.91 (0.83-0.95) das15 0.70 (0.85) 0.22 0.74 0.84 (0.71-0.91) das16 1.96 (1.30) 0.58 0.73 0.90 (0.82-0.94) das17 2.64 (1.23) 0.54 0.73 0.94 (0.89-0.97) das18 2.08 (1.36) 0.63 0.72 0.83 (0.70-0.91) das19 1.44 (1.09) 0.69 0.73 0.95 (0.92-0.97) das20 2.07 (0.98) 0.51 0.73 0.88 (0.79-0.94) das21 1.01 (1.09) 0.57 0.73 0.92 (0.85-0.96) das22 1.11 (0.89) 0.43 0.73 0.75 (0.57-0.86) das23 1.72 (1.23) 0.56 0.73 0.95 (0.91-0.97) das24 1.25 (1.07) 0.55 0.73 0.80 (0.66-0.89) total 39.80 (14.26) 1.00 0.89 0.96 (0.93-0.98) https://doi.org/10.33137/cpoj.v6i1.41454 6 khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 canadian prosthetics & orthotics journal issn: 2561-987x the persian version of the derriford appearance scale 24 khani et al., 2023 however, moss et al. concluded that by removing 5 items of the taiwanese version of das24, the cronbach’s alpha of the instrument would increase to 0.97 and therefore, the taiwanese version includes only 19 items.21 the present study also revealed that the p-das24 demonstrated excellent test-retest reliability (r= 0.96) which was similar to the findings of the original english and the taiwanese versions (r= 0.82, 0.88, respectively).19,21 as to assess the known-groups construct validity, we compared the means and total scores of the p-das24 in individuals with regard to their gender and level of involvement. in terms of gender, the total score of p-das24 did not show a significant difference between men and women. this is in contrast to the notable difference between men and women in the original english19 and brazilian/portuguese versions22 this might be due to the fact that iranian women are supposed to wear modesty dressings known as ‘hijab’ which prevents them from exposing their body in the society. however, in items das2 ‘distressed at reflection’ and das18 ‘distressed by clothing table 3: known-groups validity of the persian-das24. items sex level of amputation normal and disfigured individuals male (n=201) female (n=50) maxillof acial (n= 30) upper limb amputation (n= 25) transfemoral (n= 45) knee (n= 11) transtibial (n= 111) partial foot amputation and ankle disarticulation (n= 29) normal individuals (n= 101) disfigured individuals (n= 251) das1 123.63 133.36 182.17 166.78 113.99 113.95 111.21 112.57 208.75 163.52 p 0.36 0.00 0.00 das2 119.25 149.71 203.73 169.54 105.17 104.64 112.94 93.71 160.08 181.67 p 0.00 0.00 0.05 das3 122.64 132.26 199.92 142.35 123.00 149.36 107.04 95.67 179.84 173.06 p 0.37 0.00 0.55 das4 123.69 133.11 186.57 137.12 126.17 80.18 114.64 114.38 105.07 205.24 p 0.38 0.00 0.00 das5 127.72 113.60 196.70 147.26 131.05 139.32 105.56 95.74 188.84 170.17 p 0.20 0.00 0.10 das6 127.16 110.56 176.12 108.43 127.41 146.32 122.77 77.10 149.14 185.53 p 0.14 0.00 0.00 das7 126.97 116.54 177.87 124.44 115.94 130.73 119.27 108.71 156.51 183.87 p 0.35 0.00 0.01 das8 125.27 108.38 129.65 125.61 129.52 110.23 118.32 121.79 151.72 181.02 p 0.12 0.89 0.00 das9 122.62 137.61 194.78 161.92 123.93 126.59 106.61 101.09 176.20 176.62 p 0.17 0.00 0.97 das10 121.94 127.48 148.15 114.52 117.15 182.23 122.68 94.17 188.64 167.35 p 0.61 0.0 0.06 das11 121.97 127.46 164.43 138.37 119.35 94.50 114.84 119.36 168.74 175.44 p 0.52 0.00 0.44 das12 121.30 135.19 188.47 136.70 123.66 91.55 113.70 104.74 158.18 181.85 p 0.21 0.00 0.04 das13 128.02 114.89 179.62 133.16 117.08 123.77 122.99 90.57 173.00 177.91 p 0.21 0.00 0.64 das14 124.32 127.84 187.73 137.78 127.70 120.77 111.51 101.98 187.81 171.23 p 0.69 0.00 0.08 das15 125.43 115.32 140.02 119.87 128.28 118.23 123.14 109.66 178.33 172.25 p 0.33 0.60 0.57 das16 123.36 134.51 191.38 140.52 119.60 80.73 118.76 100.67 142.78 189.24 p 0.32 0.00 0.00 das17 124.73 128.74 185.92 147.06 123.48 103.73 113.18 107.28 129.29 194.61 p 0.71 0.00 0.00 das18 119.11 149.68 178.53 132.78 125.81 120.45 118.53 92.24 163.99 180.85 p 0.00 0.00 0.14 das19 124.73 128.73 203.63 142.58 116.37 119.68 111.08 105.84 164.72 180.49 p 0.71 0.00 0.16 das20 124.81 128.41 177.25 138.36 140.67 71.59 114.32 104.91 143.61 189.74 p 0.74 0.00 0.00 das21 128.28 105.80 181.62 121.89 127.32 104.86 114.14 110.29 165.43 178.16 p 0.03 0.00 0.25 das22 124.47 127.23 168.67 148.73 108.73 137.18 112.42 133.26 199.63 166.45 p 0.78 0.00 0.00 das23 124.16 131.13 197.32 153.92 120.06 137.27 102.69 122.31 180.20 175.01 p 0.53 0.00 0.65 das24 130.41 104.82 185.02 144.46 122.08 146.41 105.93 124.19 169.42 179.35 p 0.01 0.00 0.35 total 124.57 129.40 123.48 153.06 124.00 118.41 106.18 83.66 156.36 184.61 p 0.67 0.00 0.01 https://doi.org/10.33137/cpoj.v6i1.41454 7 khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 canadian prosthetics & orthotics journal issn: 2561-987x the persian version of the derriford appearance scale 24 khani et al., 2023 limitations’, in which certain amounts of exposure were required and women are stereotypically expected to maintain their feminine physique,29 women were reported to experience significantly higher distress than men. this was in line with the findings of a recent study revealing that body image perception was significantly different between men and women with lower limb amputation30 and women were more affected than men in relation to body image anxiety.31 however, significantly higher scores of men for item das24 ‘avoid restaurants’ revealed the higher distress experienced by them in a social occasion. women, on the other hand, had a significantly lower score for this item, which can be explained by the cultural difference between women’s dressing in an islamic community to that of a western community and how easier for muslim women is to conceal their body parts. one limitation of this study was the heterogeneity of the included participants regarding their cause of irregularity. the das24 has been developed to assess distress and dysfunction to problems of appearance in individuals with any types of visible irregularity. therefore, this questionnaire has been widely used in different sample of participants with minimal to severe forms of disfigurement. in other translated versions of this questionnaire, the study samples composed of heterogeneous individuals with visible irregularities including burn, cleft lip/palate, hemangioma, neurofibromatosis, oral cancer, and hiv/aids.21,22 that’s why we included individuals with different cause of disfigurement. facially or physically disfigured individuals encounter various psychosocial problems depending on the site and level of their amputation or disfigurement.6 our findings indicate that the total score of individuals with different disfigurements were significantly different in p-das24. similarly, moss et al. reported a significant effect of the body site affected on the scoring of participants in their study (p<0.0001).19 depression and anxiety seen in upper limb amputees are significantly higher than that of lower limb amputees.31 among lower-limb amputees, the individuals with transtibial amputation can conceal their difference/ irregularity more easily than transfemoral amputees and hence experience less scrutiny in the society.5,32 prosthetic reconstruction has proved to improve the selfimage and self-esteem of those missing a body part.33 this might be due to the fact that by means of various prosthetic designs and the advancement in their aesthetic appearance, disfigured individuals are able to conceal their difference more easily and thus avoid the stigma and distress they encounter in social occasions. the das24 has previously been used to determine changes in the distress level of patients undergoing rhinoplasty and the results showed a significant decrease in their stress level after the surgery.34 however, since it takes a considerable amount of time for amputees to adapt themselves to their prostheses and the cross-sectional nature of our study design, we were not able to compare the self-image perception and body image anxiety of amputees before and after the prosthetic reconstruction. we recommend future studies focus on the impact of prosthetic reconstruction on self-image disturbance of individuals with maxillofacial irregularity and limb loss. in terms of discriminant validity, our findings revealed that the p-das24 is able to discriminate between the normal population and the group with disfigurement (p=0.01). visible dissimilarity exposes individuals to social isolation that might occur as a result of the timidity, anxiety and distress they experience regularly.21 in a sample of taiwanese individuals, it was shown that the visibly different group scored significantly higher scores for das24 compared to the non-visibly different group.21 also, the mean scores of the general population and the clinical population participating in the study by moss et al. were significantly different (p<0.0005).19 although participants in our study were all using prosthesis as to compensate for the functional and cosmetic aspect of their body, the results showed significantly higher incidence of distress and anxiety in these individuals. this shows the sensitivity of this construct to underlying conditions leading to visible difference and its impact on social interaction of people with disfigurements. conclusion this study provided an effective translation and culturally adapted version of the das24 to assess the distress and self-image disturbance of disfigured individuals. this instrument can be used in clinical practice and researches to assess the outcomes of prosthetic reconstructions in individuals with disfigurement. acknowledgements the authors would like to thank the participants for taking part in this study. declaration of conflicting interests the authors declare that there is no conflict of interest. authors contribution • alireza khani and taher babaee: writing (original draft preparation, review and editing), design and conceptualization. • alireza khaghani, masoomeh nakhaee, timothy peter moss: design and conceptualization, writing (review and editing). all authors have read and agreed to the published version of the manuscript. sources of support this work was supported by the research ethics committee of kerman university of medical sciences. https://doi.org/10.33137/cpoj.v6i1.41454 8 khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 canadian prosthetics & orthotics journal issn: 2561-987x the persian version of the derriford appearance scale 24 khani et al., 2023 ethical approval the study protocol was approved by the research ethics committee of kerman university of medical sciences (ref: # ir.kmu.rec.1399.413, date: 27/07/1399). references 1.partridge j. psycho-social reflections on craniofacial morphogenesis. semin cell dev biol. 2010;21(3):333-8. doi: 10.1016/j.semcdb.2010.01.006 2.lansdown r, rumsey n, bradbury e, carr t, partridge j, sloper t. visibly different: coping with disfigurement. butterworthheinemann oxford.1997 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13.luza lp, ferreira eg, minsky rc, pires gkw, da silva r. psychosocial and physical adjustments and prosthesis satisfaction in amputees: a systematic review of observational studies. disabil rehabil: assist tech. 2020;15(5):582-589. doi:10.1080/17483107.2019.1602853 14.mcdonald cl, westcott-mccoy s, weaver mr, haagsma j, kartin d. global prevalence of traumatic non-fatal limb amputation. prosthet orthot int. 2021;45(2):105-114. doi: 10.1177/ 0309364620972258 15.singh vp, singh r, moss t, roy d, baral d. translation and validation of the nepalese version of derriford appearance scale (das59). mod plast surg. 2013;3(02):51. doi: 10.4236/mps.2013.32010 16.rosen jc, srebnik d, saltzberg e, wendt s. development of a body image avoidance questionnaire. psychol assess: j consult clin psychol. 1991;3(1):32.doi:10.1037/1040-3590.3.1.32 17.rosen jc, reiter j, orosan p. cognitive-behavioral body image therapy for body dysmorphic disorder. j consult clin psychol. 1995;63(2):263. doi: 10.1037//0022-006x.63.2.263 18.harris dl, carr at. the derriford appearance scale (das59): a new psychometric scale for the evaluation of patients with disfigurements and aesthetic problems of appearance. br j plast surg. 2001;54(3):216-222. doi: 10.1054/bjps.2001.3559 19.carr t, moss t, harris d. the das24: a short form of the derriford appearance scale das59 to measure individual responses to living with problems of appearance. br j health psychol. 2005;10(2):285-298. doi: 10.1348/135910705x27613 20.moss t, carr t. understanding adjustment to disfigurement: the role of the self-concept. psychol health. 2004;19(6):737-748. doi:10.1080/08870440410001722967 21.moss tp, lawson v, liu cy. the t aiwanese d erriford a ppearance s cale: the translation and validation of a scale to measure individual responses to living with problems of appearance. psych j. 2015;4(3):138-145. doi: 10.1002/pchj.91 22.martins ma, neves an, moss t, martins wh, pereira gv, pessôa kvo, et al. psychometric validation of the brazilian portuguese version of the derriford appearance scale-24 (das24) for people living with hiv/aids. healthcare (basel). 2020;8(4):569. doi: 10.3390/healthcare8040569 23.moss t, chirico a, mallia l, lucidi f, fucito a, d'aiuto m, et al. psychosocial outcomes of quadrantectomy versus mastectomy in a southern italian sample: development and needs of the italian derriford appearance scale 24. anticancer res. 2016;36(4):151926 24.cogliandro a, persichetti p, ghilardi g, moss tp, barone m, piccinocchi g, et al. how to assess appearance distress and motivation in plastic surgery candidates: italian validation of derriford appearance scale 59 (das 59). eur rev med pharmacol sci. 2016;20(18):3732-3737 25.beaton de, bombardier c, guillemin f, ferraz mb. guidelines for the process of cross-cultural adaptation of self-report measures. spine. 2000;25(24):3186-3191 26.moss t. manual for the derriford appearance scale 24 (das24). bradford on avon.2004 27.portney l, watkins m. foundations of clinical research: application to practice. f.a davis company; 2015:585-618:chap 26. 28.terwee cb, bot sd, de boer mr, van der windt da, knol dl, dekker j, et al. quality criteria were proposed for measurement properties of health status questionnaires. j clin epidemiol. 2007;60(1):34-42. doi: 10.1016/j.jclinepi.2006.03.012 https://doi.org/10.33137/cpoj.v6i1.41454 9 khani a, babaee t, khaghani a, nakhaee m, fatahi z, moss t. reliability and validity testing of the persian version of the derriford appearance scale 24 in a sample of individuals with craniofacial irregularity and amputation. canadian prosthetics & orthotics journal. 2023; volume 6, issue 1, no.3. https://doi.org/10.33137/cpoj.v6i1.41454 canadian prosthetics & orthotics journal issn: 2561-987x the persian version of the derriford appearance scale 24 khani et al., 2023 29.bodenheimer ajk, susan l. garber, trilok n. monga, carol. sexuality in persons with lower extremity amputations. disabil rehabil. 2000;22(9):409-415. doi: 10.1080/096382800406022 30.mishra sr, kumar d, yadav g, gupta a, asthana s. prosthetic satisfaction and body image among lower limb amputee: a crosssectional study. j clin diagnostic res. 2021;15(9). doi: 10.7860/jcdr/2021/49758.15404 31.desteli ee, i̇mren y, erdoğan m, sarısoy g, coşgun s. comparison of upper limb amputees and lower limb amputees: a psychosocial perspective. eur j trauma emerg surg. 2014;40(6):735-9. doi:10.1007/s00068-014-0418-3 32.horgan o, maclachlan m. psychosocial adjustment to lowerlimb amputation: a review. disabil rehabil. 2004;26(14-15):837850. doi: 10.1080/09638280410001708869 33.reaby ll, hort lk, vandervord j. body image, self‐concept, and self‐esteem in women who had a mastectomy and either wore an external breast prosthesis or had breast reconstruction and women who had not experienced mastectomy. health care women int. 1994;15(5):361-375. doi:10.1080/ 07399339409516129 34.günel c, omurlu ik. the effect of rhinoplasty on psychosocial distress level and quality of life. eur arch oto-rhino-l. 2015;272(8):1931-1935. doi: 10.1007/s00405-014-3282-1 https://doi.org/10.33137/cpoj.v6i1.41454 1 corrigendum: invisible struggles: exploring challenges faced by women with amputation in india. can prosthet orthot j. 2025; volume 8, issue 2, no. 5. https://doi.org/10.33137/cpoj.v8i2.46384 corrigendum references open access invisible struggles: exploring challenges faced by women with amputation in india in the article mentioned above¹, published in volume 7, issue 1, 2024, the authors cited mishra et al. (2020)² for the following statement: “the 2019 global burden of diseases (gbd) report highlighted that india sees about 23,500 new cases of people with amputation each year, with men making up the majority—around 20,200—while approximately 3,300 are women.” these statistics were incorrectly attributed to the 2019 global burden of diseases (gbd) report and were originally reported in mohan d (1986).³ these figures do not represent current national statistics. citation corrigendum: invisible struggles: exploring challenges faced by women with amputation in india. can prosthet orthot j. 2025; volume 8, issue 2, no. 5. https://doi.org/10.33137/cpoj.v8i 2.46384 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 2, article no. 5. 2025 1-alam j, joshi a, mir n, chawla n, sagar s. invisible struggles: exploring challenges faced by women with amputation in india. can prosthet orthot j. 2024;7(1). https://doi.org/10.33137/cpoj.v7i1.44002 2-mishra s, kumar d, gupta ak, yadav g, ghosh s. a demographic study of lower limb people with amputation in a north indian tertiary rehabilitation center. indian j phys med rehabil. 2020;31(1):11–13. doi:10.5005/jp-journals-10066-0066 3-mohan d. a report on amputees in india. orthotics and prosthetics. 1986;40(1):16–32 https://doi.org/10.33137/cpoj.v8i2.46384 https://doi.org/10.33137/cpoj.v8i2.46384 https://doi.org/10.33137/cpoj.v8i2.46384 https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2 2023 articles in this special issue has been invited and reviewed by dr. silvia ursula raschke and dr. hossein gholizadeh. d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e v o l u t i o n i n p r o s t h e t i c s & o r t h o t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x https://jps.library.utoronto.ca/index.php/cpoj/editorinchief 1 andrysek j, ramdial s. transforming p & o care with 3d printing – more than meets the eye. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.3. https://doi.org/10.33137/cpoj.v6i2.42138 stakeholder perspectives transforming p & o care with 3d printing– more than meets the eye andrysek j1,2*, ramdial s3 1 bloorview research institute, holland bloorview kids rehabilitation hospital, toronto, canada. 2 institute of biomedical engineering, faculty of applied science and engineering, university of toronto, toronto, canada. 3 orthotics and prosthetics department, holland bloorview kids rehabilitation hospital, toronto, canada. introduction with custom care being a prominent focus in the prosthetics and orthotics (p&o) industry, the ability to create unique assistive devices suggests 3d printing is the ideal solution. the appeal of additive manufacturing is its ability to produce one-off parts relatively quickly and inexpensively. while 3d printing has been around for decades, recent technological advancements have made it more relevant, meeting the design and functional requirements of the p&o field. but is 3d printing poised to transform p&o practices, and replace our traditional methods? this paper provides insight on this by examining the state-of 3d printing technology as it applies to p&o, and highlighting important considerations in bringing 3d printing into mainstream practice. the paper draws from recent published literature, as well as our learnings of 4+ years of work to implement digital workflows and 3d printing into the clinical services within our own rehab hospital. the intention of this paper is to provide useful information and guidance to the p&o sector including practitioners (i.e. clinicians and technicians implementing 3d printing in their practices), manufacturers (those developing digital workflows and 3d printers), researchers, health care funders and policy makers, users, educators, and the media, which has not always presented the topic in an accurate way. 3d printing technology 3d printing allows for the construction of three-dimensional objects from a digital model by joining or solidifying materials. many different 3d printing methods exist, utilizing a variety of materials. common printing methods include fused deposition modeling (fdm), whereby an object is built-up with an extruded filament, sintering, where a powder is fused together, or stereolithography, in which liquid resin is hardened into the desired object. polymers (plastics such as pva, pla, pet, abs, nylon) are the most commonly printed materials and relevant to p&o, but metals, resins, and even composites can also be 3d printed. open access abstract many within the prosthetics and orthotics (p&o) industry are embracing 3d printing technology to produce better devices more efficiently, cost-effectively and to improve patient outcomes. 3d printing is here to stay, but how much will it transform p&o practices? this paper explores the state-of 3d printing technology as it applies to p&o and aims to highlight important considerations for bringing 3d printing into mainstream practice. the paper draws from recent published literature, as well as experiences stemming from ongoing efforts focused on implementing digital workflows and 3d printing into p&o care. the paper examines the topic from the technological, research, economics, funding, and clinical perspectives. while 3d printing and digital workflows have advantages over traditional methods (i.e. ability to design more complex parts, reprinting and reproduction of parts, less labour intensive) there are also challenges limiting adoption. first, despite recent advancements in 3d printing technology, gaps still exist in terms of the materials and processes. for example, cost-effectively fabricating devices that are concurrently strong and durable, allow for colourful designs, and are thermoformable are still being developed. cost-wise, 3d printing may currently be more viable for small, or paediatric devices. there are also limited technical standards to ensure safe and durable devices are produced, as well as a lack of evidence and information about patient outcomes and operating costs. nevertheless, a great amount of enthusiasm and momentum exists within the industry to innovate, and with it the potential for 3d printing to one day be central to mainstream p&o care. given the many aspects of the p&o industry, collaboration and partnerships will facilitate learning from each other to advance and realize the potential of 3d printing sooner. citation andrysek j, ramdial s. transforming p & o care with 3d printing– more than meets the eye. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.3. https://doi.org/10.33137/cpoj.v 6i2.42138 keywords prosthetics, orthotics, fabrication, additive manufacturing, 3d printing, digital workflows, scanning, socket * corresponding author: jan andrysek, phd bloorview research institute, holland bloorview kids rehabilitation hospital, toronto, canada. e-mail: jan.andrysek@utoronto.ca orcid id: https://orcid.org/0000-0002-4976-1228 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.3. 2023 special issue https://doi.org/10.33137/cpoj.v6i2.42138 https://doi.org/10.33137/cpoj.v6i2.42138 https://doi.org/10.33137/cpoj.v6i2.42138 mailto:jan.andrysek@utoronto.ca https://orcid.org/0000-0002-4976-1228 https://jps.library.utoronto.ca/index.php/cpoj/index 2 andrysek j, ramdial s. transforming p & o care with 3d printing – more than meets the eye. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.3. https://doi.org/10.33137/cpoj.v6i2.42138 canadian prosthetics & orthotics journal issn: 2561-987x transforming p & o care with 3d printing– more than meets the eye andrysek j, and ramdial s, 2023 (special issue) each printing method is unique in terms of the materials that can be used, the characteristics of the fabricated parts (i.e. part geometries and size, surface finish, colors, strength, cost), and general usability (i.e. cost of or access to printer, printing time, and post processing requirements). it is crucial to highlight that no single printing technology can do it all, and the most likely scenario is that clinics will need access to a multitude of different printers, depending on their applications. for example, implementation efforts may rely on the use of a low-cost fdm printer for fabricating check or diagnostic sockets while a sintering printer such as the hewlett packard (hp) multi jet fusion (mjf) is used for the final prosthesis or orthosis requiring high strength and durability. 3d printing in p&o before diving further into 3d printing in p&o, it is important to recognize that 3d printing is closely integrated with digital workflows (i.e. the process of developing the digital models that are ultimately printed). typically, this includes some method of scanning the user’s body part and using computer-aided design (cad) software to develop the digital model. for decades, these digital workflows have included carving at the latter end to make a foam positive for molding a brace or socket, however, 3d printing has the potential to replace this final step. within our own work, it has taken considerable time and effort to figure out the digital processes for different devices (determining what scanner and design software are best, learning how to effectively use them, establishing file management etc.). applying digital workflows into p&o practice has its challenges and benefits. challenges include: incomplete solutions, inability to work with physical models, and the costs and investment needed to implement them, among others.1 however, these can be viewed as short-term hindrances as there are also benefits — the first of which being the possibility of more efficient processes for making and remaking devices. once a digital model is developed, it can be easily adjusted (digitally) and/or printed as many times as needed. if a user breaks their device, another one can be reprinted and sent to them. within our work, users have expressed their desire to have fabrication processes that require fewer visits to the clinic or hospital. another benefit is the opportunity for large data sets of digital models to inform best clinical practices around the design of devices, and to advance the design processes to be more scientifically driven.1 this could help in teaching and training, or to automate aspects of the design process to improve usability and efficiency of cad programs; ultimately improving outcomes by allowing devices to be fabricated more consistently. beyond developing and implementing workflows for making sockets and orthoses, our group has also explored the use of 3d printing in a number of other ways. the first among these is the design of terminal devices that do not exist commercially, including a custom hand,2 as well as recreational devices (such as a hockey stick attachment for a youth with a transradial prosthesis). we have also used 3d printing in the design and development of commercial prosthetic components such as the all-terrain prosthetic knee joint. the versatility of 3d printing makes it possible to explore applications that were not previously possible. for example, a market has evolved around 3d printed personalized cosmetic prosthetic covers, enabling disability to be fashionable rather than something that people try to conceal. similarly, greater personalization and customization of prosthetic liners is now possible with the advent of 3d printing of silicone. a liner can be printed with varying materials and thicknesses, to better conform and transfer the loads to the limb to improve comfort and function. variable thickness also enables orthotic and prosthetic interfaces to be designed to have compliance in certain areas and provide greater support in others, to improve comfort and load bearing capabilities. as previously mentioned, implementing digital workflows and 3d printing in p&o practice presents some unique challenges, and many are related to 3d printing technology itself. until recently and before the introduction of 3d printing technology such as the hp mjf, cost-effectively printing larger parts that met their strength requirements was a major limitation.3 however, the capital investments of acquiring a mjf printer are substantial, as are operational costs which can include such aspects as hiring a trained technician to run the equipment. at present, there is limited information on the economic aspects of using digital workflows and 3d printing as compared to traditional workflows, making it a leap of faith for those interested in implementing these new technologies.4 an additional financial consideration which remains a gray area in some health care systems, is reimbursement. however, professionals and the p&o industry are advocating for approval of new and proven technologies. beyond the economic aspects, concerns also persist about the suitability of existing 3d printing technology for use in p&o. an important aspect is strength and durability, given the critical role that p&o devices play in the lives of their users. strength is determined not only by the material used, but also the printing process. for example, fdm printed parts are prone to weakness between printed layers, resulting in potential fracture points. sintered parts (such as with the mjf) are much more isotropic and avoid this but come at a much higher cost as previously mentioned. a related challenge is the absence of standards or protocols for strength testing components such as sockets and orthoses. the design of custom p&o devices such as sockets or orthoses is largely based on best practices and the practitioner’s experience, and such experiential evidence is still limited for non-traditionally made devices. structural testing standards such as iso 10328 do not cover p&o components beyond prosthetic knee joints and feet. https://doi.org/10.33137/cpoj.v6i2.42138 3 andrysek j, ramdial s. transforming p & o care with 3d printing – more than meets the eye. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.3. https://doi.org/10.33137/cpoj.v6i2.42138 canadian prosthetics & orthotics journal issn: 2561-987x transforming p & o care with 3d printing– more than meets the eye andrysek j, and ramdial s, 2023 (special issue) further, the diversity of printing materials and methods, as well as device requirements, complicates the establishment of accepted standards and practices. nevertheless, general guiding principles for 3d printing medical devices are being established. the standards identify important technical considerations for manufacturing and testing of 3d printed medical devices including point-of-care and patientmatched (custom) devices which are relevant to the p&o industry.5 other characteristics are also important, but not easy to achieve with existing 3d printers. printed materials should ideally be thermoformable to allow for both immediate adjustments to parts such as sockets and orthoses during fitting and future adjustments due to growth or other physiological changes. however, the most promising printing methods (such as the hp mjf) are not ideal in this respect. the sintered mjf nylon material has limited thermoformability, and the application of heat has the unfortunate effect of changing the color and finish of the surface, thus compromising aesthetics of the finished piece as well as possibly the mechanical properties. the mjf printer is also limited in terms of colors that can be printed, with dark grey being the default. hp previously sold a printer that gave us a variety of choices, but these colour features are no longer available. this is unfortunate, as many users (kids and adults alike) see color as an important aspect of device personalization. in contrast, fdm printers can easily print in color, however, as noted earlier the strength and surface finish are questionable. in the case of diagnostic sockets that need to be transparent in addition to being thermoformable, the options are even more limited. curable resins that are transparent are not thermoformable. plastics used in fdm are thermoformable, but the fdm process limits transparency due the way the filament is layered to make the parts. optimization of printing parameters and surface treatments can help to increase transparency, but currently there is little guidance on how to achieve acceptable results in practice. trade-offs exist, and many of these unique challenges are left up to the p&o industry to find solutions. unraveling more of the details, there are other challenges to overcome. for example, currently there is no simple way to digitally capture the changes made by heat forming a diagnostic socket for the finalization of the model and printing of the definitive socket. scanners that can effectively capture the inside shape of a socket, especially small sockets, are not available. we even went as far as trying dental scanners, but these are not designed to reconstruct topologies relevant to p&o devices. one could fill the diagnostic socket with plaster or alginate and then digitally scan in this positive model, but it would be ideal if this “traditional workflow” step could be avoided. another restriction is size. not only does the cost of the printed part increase with size, but most printers have print volumes that cannot accommodate larger devices. for example, current mjf printers have a build volume that can print a smaller afo, but not a large adult one. joining two printed parts to make a larger device is possible but requires extra steps and may compromise strength. 3d printing at present may be best suited for smaller devices such as foot orthotics, and also pediatric over adult care. the possibilities that 3d printing offer are exciting. one only needs to go to any p&o forum or congress, to see all of the innovation that companies, researchers, and health care are driving. from improvements to digital design and data management software and new printing technologies, to service bureau models for central fabrication and beyond. however, current 3d printing technology does not fully meet the needs of the p&o industry and as such, the future remains uncertain. the ideal 3d printer would be costeffective and not only produce strong and durable parts with a good finish, but also colors and designs that users desire. processes and materials that are concurrently able to provide the important features (strength, durability, good finish, thermoformability, colors, biocompatibility etc.) are needed. additionally, reduced print times (i.e. < 1 hour) would allow devices to be fabricated and tested during a single session, thus reducing the number of appointments and overall healthcare costs and burden on users. it is a lot to ask for and expect from 3d printing to meet all these criteria. the alternative is that clinical practices continue to adapt to best utilize the existing tools. the mainstream adoption of 3d printing in p&o would change practice, and it must not compromise quality of devices, treatment and services. given the diversity of p&o care, it will continue to take ingenuity and craftiness to address the many practice nuances over time as was done with traditional processes. one important aspect of this, is that we are able to learn from each other. in our efforts to implement digital technology workflows, we have been very fortunate at the willingness of other clinics, hospitals, researchers and even companies to share their expertise and learnings with us. these partnerships help us move forward with greater ease and to apply digital workflows in our care. it is our goal to reciprocate and support others. we need to strive to continue to bring the communities interested in digital workflows and 3d printing together. some considerations include establishing special interest groups, forums or networks and to collaborate globally (i.e. international society for prosthetics and orthotics ispo). the discussions must also involve manufacturers, who can ultimately help address the limitations of existing printing technology, and policymakers and funders, who can help to remove funding and regulatory barriers in how we can implement 3d printing in practice. call to action is 3d printing the future of p&o care? will it continue to be a way that we make the occasional one-off device, or will it more profoundly transform our practice? it is too early to https://doi.org/10.33137/cpoj.v6i2.42138 4 andrysek j, ramdial s. transforming p & o care with 3d printing – more than meets the eye. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.3. https://doi.org/10.33137/cpoj.v6i2.42138 canadian prosthetics & orthotics journal issn: 2561-987x transforming p & o care with 3d printing– more than meets the eye andrysek j, and ramdial s, 2023 (special issue) know and will depend on the future advancements in the technology itself, the p&o ecosystem, the validation from all involved — especially our users, and also our continued willingness and ability to work toward implementing it. the driving elements, and metrics to indicate that we are on the right track, will boil down to whether the needs of clients can be served more efficiently and effectively. this will require shared learnings from the users, clinical, technical and research groups, and utilizing available evidence about the quality of care and cost-effectiveness in comparison to the status quo. acknowledgements we would like to acknowledge all those that have contributed to this work over the years including many members of the clinical and technical teams within the orthotics and prosthetics department at holland bloorview, and most notably elaine ouellette, neil ready, kerri kelland and amy richardson. other contributors to the work that informed this paper include calvin ngan and harry sivasambu from the bloorview research institute. we also thank boundless biomechanical bracing for their insights on the hp mjf printing. last but not least, many thanks to the clients of holland bloorview that have participated in trialing digitally made devices. declaration of conflicting interests the authors have no conflicts of interest to declare related to this paper. authors contribution both authors contributed equally to the research and the writing of this manuscript. sources of support holland bloorview foundation grants from 2021 to 2023. natural sciences and engineering council (nserc) discovery grant 493032. nserc alliance grant 514883. the war amps. references 1.ngan c, sivasambu h, kelland k, ramdial s, andrysek j. understanding the adoption of digital workflows in orthotic & prosthetic practice from practitioner perspectives: a qualitative descriptive study. prosthet orthot int. 2022;46(3):282-289. doi: 10.1097/pxr.0000000000000107 2.eshraghi a, yoo j, klein j, mckenzie i, sebaldt g, leineweber m, et al. a custom, functional and lifelike passive prosthetic hand for infants and small toddlers: clinical note. prosthet orthot int. 2020;44(3):180-184. doi: 10.1177/0309364620909276 3.ribeiro d, cimino sr, mayo al, ratto m, hitzig sl. 3d printing and amputation: a scoping review. disabil rehabil assist technol. 2021;16(2):221-240. doi: 10.1080/17483107.2019.1646825 4.roberts a, wales j, smith h, sampson cj, jones p, james m. a randomised controlled trial of laser scanning and casting for the construction of ankle-foot orthoses. prosthet orthot int. 2016;40(2):253–61. doi: 10.1177/0309364614550263 5.technical considerations for additive manufactured medical devices: guidance for industry and food and drug administration staff [internet]. food and drug administration. 2017. [cited sep 22, 2023]. available from: https://www.fda.gov/regulatoryinformation/search-fda-guidance-documents/technicalconsiderations-additive-manufactured-medical-devices authors scientific biography dr. jan andrysek is a senior scientist at the bloorview research institute of holland bloorview kids rehabilitation hospital and an associate professor at the institute of biomedical engineering, university of toronto. his research program focuses on the development of treatments and assistive technologies for children and youth with physical disabilities. specific areas of study include prosthetic and orthotic limb design and control, bio sensing, biofeedback and gait training systems, and understanding the global need for prosthetic and orthotic technology and its impact on mobility, physical function, and quality of life. he is the recipient of awards including the 2017 ontario profession engineers engineering medal for research and development. in 2019 dr. andrysek was elected an american institute for medical and biological engineering (aimbe) fellow. he is also the co-founder and chief scientific officer at legworks inc., a social for-profit enterprise focused on improving prosthetic technologies and care for individuals globally. sandra ramdial is a certified prosthetist. she is the past operations manager for the orthotic and prosthetic department at holland bloorview kids rehabilitation hospital where she led a group of clinical and technical professionals and had direct involvement in client care. she has over 35 years of experience in the field including 22 years at holland bloorview and was part of the professional and clinical services team at otto bock healthcare canada where she managed the custom silicone group and a key clinical ambassador and educator for upper limb prosthetics. sandra is the past president of the canadian association of prosthetics & orthotics and the international society for prosthetics & orthotics (ispo) canada and the past secretary-treasurer for the association of children’s prosthetic-orthotic clinics. she continues to be involved in orthotics & prosthetics and is presently the president elect for the international board of ispo. in addition to her extensive experience, she brings an even greater amount of enthusiasm and passion for research and development, and new technologies to the field. https://doi.org/10.33137/cpoj.v6i2.42138 https://www.fda.gov/regulatory-information/search-fda-guidance-documents/technical-considerations-additive-manufactured-medical-devices https://www.fda.gov/regulatory-information/search-fda-guidance-documents/technical-considerations-additive-manufactured-medical-devices https://www.fda.gov/regulatory-information/search-fda-guidance-documents/technical-considerations-additive-manufactured-medical-devices all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 7, issue 2 2024 research article brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i2.44494 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 research article development and evaluation of an anteriorly mounted microprocessorcontrolled powered hip joint prosthesis brannen k1, baddour n1, cho l1, langlois d2, dumond p1, lemaire e.d3,4* 1. department of mechanical engineering, faculty of engineering, university of ottawa, ottawa, canada. 2. össur, grjothals 1-5, 110 reykjavik, iceland. 3. department of medicine, faculty of medicine, university of ottawa, ottawa, canada. 4. center for rehabilitation research and development, ottawa hospital research institute, ottawa, canada. introduction lower limb prostheses facilitate daily ambulation for people with amputation. microprocessor powered lower limb prosthetics technology, primarily for knee joints, can improve balance and stability1 and can lower energy expenditure, leading to increased daily activity and overall satisfaction.2 however, similar solutions for hip joints are not available. considering that walking performance is greatly affected by proximal amputation locations,3 many people with hip disarticulation (hd) and hemipelvectomy (hp) amputation experience difficulty walking with prostheses. as a result, more than 50% of such individuals opt for alternative solutions such as wheelchairs for daily mobility.4 a powered prosthetic hip joint could solve common challenges in current hip-knee-ankle-foot (hkaf) prostheses, namely stability, metabolic cost, and range of motion, allowing people to recover a more natural gait.5 commonly used prosthetic hip joints can be grouped into single-axis or polycentric joints, based on the number of pivot points and linkages involved in the mechanism. while open access abstract background: prosthetic solutions for individuals with hip disarticulation and hemipelvectomy amputations currently rely exclusively on passive hip joint mechanisms. although powered knee and ankle joint prostheses have improved gait in people with amputation, no powered hip joint options are commercially available. objective: to develop and validate the mechanism, structural integrity, and design of an anteriorly mounted powered hip joint prosthesis. methodology: a microprocessor-controlled powered hip joint prosthesis (php) was developed, incorporating a cable-and-pulley transmission system. stress calculations and finite element analysis (fea) were performed to ensure that the device can withstand the forces from daily activities. the prototype underwent mechanical strength testing in accordance with international organization for standardization (iso) 15032:2000 standards, ensuring suitability for user loads of up to 100 kg. for functional testing, three able-bodied individuals were video recorded while walking with the power hip in a prosthesis simulator. for each participant, hip angles and stride parameters during level walking were assessed by analyzing five gait cycles. findings: the novel php met most of the design criteria; however, it protruded 56 mm anteriorly from the lamination plate, exceeding the specified criterion of 20 mm. the joint's range of motion included 22° of extension and 145° of flexion. the joint prototype's height was 347 mm, and it weighed 3.9 kg. furthermore, it passed iso 15032:2000 strength tests, withstanding a 3360 newton (n) load without failure. the device successfully enabled able-bodied individuals to walk using a hip disarticulation simulator and supported a 98 kg user during level walking. conclusion: the microprocessor-controlled php exhibited successful performance in both mechanical strength and functional testing. future work is needed to optimize and assess the design, which could reduce the device's weight and size. a complex control system to adjust gait based on pelvic motion is currently under development. article info received: december 10, 2024 accepted: january 31, 2025 published: february 7, 2025 citation brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessorcontrolled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.4449 4 keywords microprocessor-controlled prosthesis; powered hip joint; hip disarticulation; hemipelvectomy; prosthesis design; amputation; lower limb amputation; hip–knee–ankle–foot prosthesis * corresponding author: professor edward lemaire, phd affiliation: department of medicine, faculty of medicine, university of ottawa, ottawa, canada. e-mail: elemaire@uottawa.ca orcid id: https://orcid.org/0000-0003-4693-2623 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 2, article no. 7. 2024 https://doi.org/10.33137/cpoj.v7i2.44494 https://doi.org/10.33137/cpoj.v7i2.44494 https://doi.org/10.33137/cpoj.v7i2.44494 mailto:elemaire@uottawa.ca https://jps.library.utoronto.ca/index.php/cpoj/index 2 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 polycentric joints like the ottobock helix 3d have improved gait compared to other devices,4 any passive hip joint requires the user to generate hip moments by using lumbar spine and pelvis movements for propulsion. this comes with the disadvantage of high energy expenditure while walking,3-6 asymmetrical gait,7 and an increased risk of long-term injury from musculoskeletal imbalances.8 microprocessor-controlled knee joints have better capability to react to user movement, detecting harmful movements like trips and stumbles to reduce injury risk.9 these devices can also adapt to various walking environments (e.g., level ground, ramp, stairs). given that the average adult performs approximately 60 sit-to-stand movements daily,10 the added support and assistance from a powered prosthesis could reduce sit-stand asymmetry and load on the intact leg in individuals with amputation. a powered prosthetic hip joint could enable step-over-step stair ascent, a capability currently lacking in people with hd and hp amputation.11 a powered prosthetic hip joint was reported by ueyama et al.,12 who prototyped a device using direct current (dc) motors positioned within the thigh to power the hip and knee joints, with the joints sharing microcontroller boards, battery, and sensor data. an able-bodied participant successfully walked with the prosthesis, but the device required users to wear the battery in a waist bag and the prosthesis would not fit under clothing. a laterally mounted powered hip joint prosthesis was previously developed by mroz et al.13 with the hip axis of rotation similar to the anatomical joint center. a cable driven transmission system transferred motor torque from the prosthetic thigh to the hip axis of rotation. the thigh chassis that housed the battery and electronics was separately validated.14 a weight bearing strut with double row steel ball bearings provided clearance for the device to swing beneath the pelvis.13 able-bodied participants successfully walked with the laterally mounted php using a prosthesis simulator. although this prototype successfully met most of the design requirements, there is still room for improvement in terms of weight and size. this paper explored the design and development of the main mechanical and structural components of an anteriorly mounted php, focusing on the rope and pulley transmission system that drives the mechanism. the anteriorly mounted design provides a compact system with the motor and electronics in the thigh, distal to the joint center of rotation. a successful php could greatly enhance safe mobility for people with hd or hp amputations. methodology design requirements based on existing international standards, literature review, the research team's clinical experience working with hd, hp or transfemoral amputation, and discussions with experts, the following design criteria were selected: • joint angular velocity of at least 150 °/s.15,16 • maximum hip moment of 96 nm to accommodate for a 100 kg user.17,18 • joint range of motion of 130° flexion and 20° extension.18 • device weight should remain under 4 kg. this is compared to össur’s power knee weighing 3.2 kg using the same actuator and battery.19 • device strength based on iso 15032:2000 standards for prosthetic hip joints:20 o withstand 2240 n load for 30 s without deformation >15 mm, and 3360 n without ductile failure. o joint must withstand 2x106 cycles from 50 n to 1330 n without failure. • must comfortably fit under user clothing: o anterior protrusion less than 20 mm from the center of lamination plate. o lateral protrusion less than 80 mm from center of lamination plate.21 o medial protrusion less than 50 mm from center of lamination plate. • device length must remain under 378 mm (using anthropometric data, thigh length is 0.245*height, or 378 mm for the 15th percentile women height).21 • no finger traps or sharp edges for user safety. design and development of php prototype the php main components (figure 1) were designed using solidworks software (version 2020). all metal components were made with aluminum 2024-t4 or 17-4 ph stainless steel, except for the off-the-shelf parts like screws and retaining rings. to make the prototype lighter, aluminum was used as much as possible, but steel was needed for parts requiring more strength. note that the actuator is located below the joint to minimize anterior protrusion. actuator torque is transmitted through the cable and pulley to the joint center.22 the cable and pulley transmission system consists of four equally sized pulleys connected by two high strength steel cables (figure 2). when torque is applied by the actuator to the bottom pulley, tension is applied to the cable and the assembly rotates around the top pulley in the opposite direction. much like a belt drive transmission, the mechanism transfers torque over an extended distance with less components and weight. pulleys diameters are also constrained since a small diameter requires greater tension on the cable to achieve the same torque (figure 2). therefore, 52 mm diameter pulleys were chosen to maintain the system’s integrity while balancing performance and compactness. https://doi.org/10.33137/cpoj.v7i2.44494 https://www.ottobock.com/en-ca/product/7e10 3 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 figure 1: powered hip joint components. transmission system: drive train composed of four pulleys of equal diameter and steel cables enabling joint flexion and extension (steel cables are not shown in this figure); shafts: structural components that bear user weight and tension from the pulleys. the proximal shaft connects the top hinge and bearing housing, and the distal shaft applies torque to the bottom pulleys; bearing housing: connects to the top of the actuator and facilitates joint rotation around the top shaft; top hinge: interface between the lamination plate and joint center; lamination plate: plate embedded in the prosthetic socket to attach the joint; actuator: össur power knee™ microprocessor-controlled motor modified for the php, providing torque and power to the system; mounting components: attachment ring and medial attachment piece secures the actuator to the attachment plate (chassis’ top plate); chassis: contains the electronic and the battery (össur power knee). the cables were crossed in a figure-eight configuration, to ensure that the input torque from the motor and the reaction torque from the fixed pulleys (top) are in the same direction. without a counteracting torque to establish equilibrium, the entire system rotates. pulleys of equal diameter were selected, ensuring equal speed and torque between the top and bottom pulleys, to deliver the required 96 nm of torque and 150°/s angular velocity. the pulleys were machined from 17-4 ph h900 steel to withstand high radial loads imposed by the cable and were designed to have a minimal diameter to reduce weight and space. the php pulleys were designed to allow the rope to anchor inside the part, to prevent slipping (figure 2). the rope loop fits around a groove on the inside of the pulley and a hole on the top allows the rope to stick out and wrap around the pulley. high strength ropes or cables are required to meet the load requirements and provide better flexibility, and greater strength. to achieve a 96 nm hip moment with a 52 mm diameter pulley, 4200 n of tension must be applied to the rope. liquid crystal polymer (lcp) ropes such as vectrantm (https://kuraray.us.com/products/fibers/vectran/) meet these requirements, but steel cabling was selected for the initial prototype testing due to ease of crimping on terminators (figure 2). the top hinge is secured to both the top shaft and lamination plate (figure 1), while the bottom hinge is mounted on bearings. the bearing housing connects to a female pyramid adapter that is secured to its male counterpart on the actuator (figure 2). needle roller bearings were selected for this application for their ability to handle high radial loads while occupying minimal space. like many transmission systems, the cable and pulley system must be pre-tensioned to ensure control responsiveness. if slack exists at an idle position, the actuator must first turn to take up the slack before joint movement can occur. for optimal performance, the joint must rotate synchronously with the actuator to avoid backlash caused by the oscillating nature of the mechanism. this issue was addressed by implementing a novel tensioning system consisting of multiple keyways on the top shaft and pulleys. the shaft contains eight equally spaced keyways, while the pulleys contain nine. this results in 72 possible orientations of the top pulleys where the top pulleys can be rotated and secured every 5° via a compatible keyway (figure 3). additionally, the system requires the medial and lateral pulleys to be tensioned in opposite directions, necessitating the use of two separate pulleys on the same shaft. two main mechanisms were used to mount the php to the top plate of an aluminum chassis that holds the battery and other electrical components (figure 4). a cylindrical groove was machined out of the chassis’ top plate to ensure full contact with the actuator’s bottom. the attachment ring contains a circular bolt pattern that fastens the ring to the circumference of the actuator. two tapped holes were located underneath the attachment ring to secure the ring to the chassis’ top plate, restricting movement of the actuator’s outer casing. an additional medial attachment piece was fastened to the medial side of the actuator’s center, providing a secondary bracing mechanism to prevent the actuator from lifting off the chassis. the php prototype was constructed from an assembly of machined parts and off the shelf components. mechanical drawings with appropriate dimensions and tolerances for each part were made before machining. lamination plate top hinge battery chassis chassis’ top plate medial attachment actuator bearing housing electronic attachment ring pulley shafts transmission system m o u n ti n g c o m p o n e n ts https://doi.org/10.33137/cpoj.v7i2.44494 https://kuraray.us.com/products/fibers/vectran/ 4 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 an össur power knee™ microprocessor-controlled motor was modified for the php, providing torque and power to the system. the lamination plate was designed to fit a prosthesis simulator that allowed able bodied participants to test the prototype.23 testing and validation static load testing static load testing ensured that the php was strong enough to withstand operating loads of a 100 kg person, using the procedures outlined in iso 15032:2000 prostheses – structural testing of hip joints.20 two testing conditions were evaluated: medial-lateral (ml) and anterior-posterior (ap) extension (figure 5 and figure 6). the php was tested in a servo hydraulic testing system. this study only explores prototype functionality under short-term use. since the servo hydraulic testing system could only move along one axis, an adjustable testing rig was developed. the php top hinge was bolted onto an aluminum block attached to a pole and adjustable moment arm. the bottom of the chassis was attached to a similar assembly by a pyramid adapter. the testing procedure was as follows: figure 2: left: schematic of the php and a pulley; middle: illustration of the steel ropes and pulleys; right: free body diagram of the crossed cable system, where t1 is the input torque from the actuator acting on the driving pulley, f12 is the tensile force from the cables on the pulleys, m2 is the reaction moment on the fixed pulley shaft, r1, and r2 are the reaction force of the cable force on the pulleys. figure 3: offset keyway tensioning solution. the red key demonstrates one of the pulley positioning possibilities. top hinge bottom hinge female pyramid adapter distal pully (medial) distal pully (lateral) actuator thigh chassis steel ropes for medial pulleys steel ropes for lateral pulleys f12 f12 r 2 m 2 r 1 t 1 x x shaft contains eight equally spaced keyways pulleys contains nine equally spaced keyways female adapter actuator with male adapter lamination plate red key https://doi.org/10.33137/cpoj.v7i2.44494 5 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 1. set force to a 1024 n settling load and hold for 30 s. 2. return load to zero. 3. increase load at a rate of 200 n/s until 3360 n. 4. return load to zero. the ml test was set up in the fully extended position, as shown in figure 5. all moment arm lengths and angles were based on the iso 15032:200 0 medial lateral loading conditions. functional testing the functional testing protocol was approved by the university of ottawa office of research ethics and integrity. functional testing was performed by three able-bodied participants (members of the research team) on a prosthesis simulator23 that enables them to walk on a hkaf prosthesis. informed consent was obtained from all participants, and the inclusion criterion was being ablebodied without any balance issues. the assembly consisted of the php, össur rheo 3 knee joint, and össur pro-flex xc foot. participants wore an elevated outsole on the intact limb (left leg) to create 40 mm ground clearance for the right foot during stance (figure 7). in this setup, only the prosthesis simulator and the left leg contacted the ground.23 participant subjective feedback was also recorded comparing the php to previous helix3d walking tests. each participant was first trained on the simulator using the ottobock helix 3d joint and learned to walk comfortably before continuing with trials using the php. one or two canes were also used by the participants for support and safety. the participants were given one training session to familiarize themselves to walking with the php on the simulator and one testing session where the data was recorded. for functional testing, a simple control system was implemented for the php. it applied a predetermined and repeated gait cycle, tuned to operate at a specific pace to provide a comfortable gait pattern for all users. this cycle began at 40° flexion at heel strike and then extended to 20° extension. once full extension was reached, the joint swung to 44° flexion and slowly returned to the initial condition of 40° flexion. a 2.5 s stride time was implemented to suit the participants. php gait profile used for functional testing was illustrated in the authors’ previous publication.13 for functional testing, five gait cycles were video recorded using a smartphone where no large stumbles were present and where the participant did not contact the floor with their prosthetic side natural foot. the videos were analyzed using the kinovea video annotation tool to measure the hip angle (angle between the torso and the line connecting the hip joint and the knee) and determine stride parameters. initial contact and toe-off times were used to identify the step times of each stride for each participant. figure 4: left: attachment ring and medial attachment piece bracing the outer casing of the actuator to the top plate of the electronics chassis; middel: the thigh chassis that housed the battery and electronics; right: joint dimensions. medial attachment 3 4 7 m m 1 7 1 m m chassis’ top plate with a cylindrical groove attachment ring https://doi.org/10.33137/cpoj.v7i2.44494 6 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 figure 5: left: medial-lateral mechanical testing (iso-15032:2000) conditions for the powered hip prosthesis; right: setup for static load. figure 6: left: anterior-posterior mechanical testing (iso-15032:2000) conditions for the powered hip prosthesis; right: setup for static load. applied force applied force applied force applied force mounting block mounting block load application point load application point adjustable testing rig adjustable testing rig https://doi.org/10.33137/cpoj.v7i2.44494 7 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 figure 7: hip disarticulation simulator23 setup with php, össur rheo 3 knee joint, and össur pro-flex xc foot. participants wore an elevated outsole on the intact limb to create 40 mm ground clearance for the right foot during stance. results successful construction of the prototype validated the php manufacturing and assembly methods. the device weighed a total 3.9 kg, including the battery, electronics, and chassis. this prototype, similar to the ottobock helix 3d, features right and left configurations. in this study, a right php was manufactured and tested. static load test results the test procedure was the same for both ml and ap, with the only difference being the loading conditions. figure 8 depict the force and displacement versus time profiles of the ml test and ap tests, respectively. both tests withstood the 3360 n ultimate strength test, displaying no signs of ductile fracture or plastic deformation. the ml test displayed a maximum displacement of 8.5 mm, whereas the ap test displayed less displacement at 4 mm (figure 8). functional testing results three male volunteers (members of the research team) participated in functional testing (table 1). heel contact and toe-off times were used to identify the step times of each stride for each participant. the results of the five-stride test are shown in figure 9. maximum flexion and extension angles were identified in table 2. the average range of motion during level walking was 47.2 ± 6.4°, which remained within the sufficient preprogrammed range of 64°. the average step time on the prosthetic side averaged 0.63 times the intact side. the average swing time for the intact side was 0.29 ± 0.04 s and the average prosthetic leg swing time was 1.08 ± 0.10 s (table 3). figure 8: top: php force and displacement profiles for mediallateral static load testing; bottom: php force and displacement profiles for anterior-posterior static load testing. table 1: participant information. participant a b c sex male male male age (years) 44 28 25 height (cm) 178 180 175 weight (kg) 95 95 98 number of canes used by participants 1 2 2 0 1 2 3 4 5 6 7 8 9 0 500 1000 1500 2000 2500 3000 3500 4000 0 20 40 60 80 100 d is p la c e m e n t (m m ) f o rc e ( n ) time (s) force displacement 0 1 2 3 4 5 0 500 1000 1500 2000 2500 3000 3500 4000 0 20 40 60 80 100 d is p la c e m e n t (m m ) f o rc e ( n ) time (s) force displacement 40 mm ground clearance 40 mm outsole https://doi.org/10.33137/cpoj.v7i2.44494 8 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 table 2: functional testing range of motion. participant maximum flexion (°) maximum extension (°) range of motion (°) a 21.1 ± 4.0 19.3 ± 1.7 40.4 ± 4.3 b 41.4 ± 2.5 4.3 ± 8.9 45.7 ± 9.2 c 39.3 ± 2.5 16.1 ± 3.5 55.3 ± 4.3 average 33.9 ± 3.1 13.2 ± 5.6 47.2 ± 6.4 table 3: functional testing gait parameters with percentages of average stride time. participant a b c average stride time (s) 2.35 ± 0.07 2.38 ± 0.10 2.45 ± 0.09 2.39 ± 0.09 step time (s) prosthetic 1.50 ± 0.10 (64 %) 1.19 ± 0.06 (50%) 1.24 ± 0.08 (50%) 1.31 ± 0.08 (55%) intact 2.04 ± 0.06 (88%) 2.09 ± 0.02 (89%) 2.09 ± 0.10 (86%) 2.07 ± 0.07 (88%) swing time (s) prosthetic 0.85 ± 0.07 (36%) 1.18 ± 0.14 (50%) 1.22 ± 0.08 (50%) 1.08 ± 0.10 (45%) intact 0.27 ± 0.02 (12 %) 0.27 ± 0.03 (11%) 0.34 ± 0.05 (14%) 0.29 ± 0.04 (12%) double support time (s) 0.94 ± 0.16 (40%) 0.91 ± 0.08 (38%) 0.89 ± 0.06 (36%) 0.91 ± 0.11 (38%) cadence (steps/min) 51.2 ± 1.4 50.6 ± 2.2 49.0 ± 1.9 50.3 ± 1.8 step time ratio 0.73 ± 0.05 0.57 ± 0.03 0.59 ± 0.06 0.63 ± 0.05 all three participants stated that the php was easier to operate than the non-powered helix3d joint, specifically noting that manual swinging and large pelvic rotation were not necessary for propulsion (subjective feedback). the participants also noted that the additional weight of the php compared to the helix3d did not cause any problems. figure 9: php hip flexion angle vs time across 5 strides for participant a (blue), participant b (red), and participant c (green). design requirements evaluation the final design tested in this study met most of the design criteria (table 4). discussion a novel microprocessor-controlled php was designed and evaluated for both strength and function. the pulley and cable power transmission system was successful in transmitting rotational power from the actuator to the hip joint. the final design met most of the design criteria, including mechanical strength tests. the php was also tested with able-bodied participants using a hip disarticulation prosthesis simulator, where ambulation was successful. the device weighed 3.9 kg, putting the php under the 4.0 kg weight limit. the functional testing participants noted that this 3.9 kg weight did not feel heavy while walking or noticeably impede their motion. the anterior protrusion criterion was 20 mm, but the prototype tested in this study protruded 56 mm. future work is needed to optimize and assess the design, which could reduce the device's weight and size. the design requirement for the php was to support users up to 100 kg. the php successfully supported a 98 kg user during functional testing, which is close to the required 100 kg. the php also successfully passed iso mechanical testing designed for users up to 100 kg. the strength requirements outlined in iso 15032:2000 were to withstand a 2240 n load for 30 s without failure or deformation greater than 15 mm, withstand a 3360 n load without ductile failure, and withstand 2×106 cycles between 50 n and 1330 n without failure. the php withstood a 3360 n load without failure or deformation greater than 15 mm. cyclical testing was not conducted on the php; however, calculations and fea simulations indicate that the device should be able to withstand fatigue from the cycles outlined in the iso standard. during level walking, the php achieved an average of 13.2 ± 5.6° of extension and 33.9 ± 3.1° of flexion (figure 9). the maximum extension and flexion measured with a protractor were 22° and 145°, respectively, successfully surpassing the 20° hip extension and 130° hip flexion requirements. the final php power transmission gear ratio was 1:1. therefore, the device should have the same maximum torque and angular velocity as the össur power knee™ microprocessor-controlled motor. the maximum actuator torque is 96 nm and the maximum angular velocity is 300°/s, reaching the outlined 96 nm and 150°/s outlined criteria. the actual hip moment was not measured; however, moments were enough to successfully propel all three functional testing participants forward and support body weight, allowing level ground walking. geometric constraints were established to ensure the php could fit comfortably under a user’s pants. the first -30 -20 -10 0 10 20 30 40 50 0 2 4 6 8 10 12 14 h ip a n g le ( ° fl e x io n ) time (s) participant a participant b participant c https://doi.org/10.33137/cpoj.v7i2.44494 9 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 geometric restriction was that the php could not protrude more than 20 mm from the top of the lamination plate. the final prototype for initial testing protruded 56 mm anteriorly, failing to meet the criterion. even though this criterion not met, this prototype could still be accommodated under loose-fitting pants. the php could also not protrude more than 80 mm laterally or 50 mm medially from the center of the lamination plate. 71 mm lateral protrusion and 50 mm medial protrusion were measured on the final device. the device length was also controlled to ensure a large population could use the device. the php could not have any uncovered finger traps. a cover was designed to go over the pulley system, where the main finger traps occurred. however, the cover no longer fit over the pulleys when the steel cables were used for functional testing. a cover that encompasses the entire device would also be more successful because there is still potential for a finger to be caught between the bearing housing and the lamination plate with the current design. therefore, this requirement was only partially met and could be improved upon. from the functional test results, discrepancies in the joint range of motion data were present, where the recorded range of motion was 8.3° less than the joint’s preprogramed range of motion. this difference was likely the result of a difference in step timing (landing early) compared to the pre-programmed gait profile. offsets in the recording angle can cause inaccuracies in the measurements since the footage was recorded in 2d. for future work, biomechanical data should be collected on people with hd or hp amputations, using 3d motion capture systems to accurately measure gait data. another key finding from the functional test results is that the user tends to spend more time on their intact leg compared to the prosthesis. this causes asymmetrical gait patterns and is likely the result of the user feeling less stable on the prosthetic side. to be more specific, when the participant is supported with the prosthesis, they will quickly swing their intact leg in front for support. feelings of discomfort and instability may be reduced with more training and experience with the prosthesis, along with a fully developed intelligent control system. the php tested in the current study weighs 3.9 kg, meeting the design criteria. ueyama et al.,12 who prototyped a device using direct current (dc) motors, also noted that developing a lightweight powered hip joint prosthesis is challenging. they reported that the socket weighed 1.5 kg, resulting in a total robotic hdp weight of 11.3 kg. they did not provide the joint's weight separately. as well, electronics and battery were located at the waist, not integrated into the prosthesis. similarly, mroz et al.,13 who evaluated a php mounted laterally, mentioned weight as a challenge, with their prototype weighing 5.7 kg. further work is needed to decrease the php's size and weight. limitations there are some limitations in this study. since the control system was not fully developed during the primary functional testing, a simple control system was implemented that could only be used for level walking at a fixed speed. additionally, the study was conducted with only three ablebodied individuals. evaluation with hd or hp is required in future evaluation. table 4: design criteria and results. requirement actual value met the design criteria device weight maximum 4.0 kg measured 3.9 kg yes user weight maximum 100 kg tested with 98 kg user passed strength tests for 100 kg user yes strength withstand 2240 n load for 30 s without failure or deformation > 15 mm withstand 3360 n load without ductile failure withstand 2×106 cycles between 50 n and 1330 n without failure passed static loading tests fea simulations indicated that device should pass cyclical loading test yes range of motion minimum 20° hip extension 22° hip extension (measured with protractor) yes minimum 130° hip flexion 145° hip flexion (measured with protractor) yes hip moment minimum 96 nm 1:1 gear ratio should provide 96 nm hip moment yes* angular velocity minimum 150 °/s 1:1 gear ratio should provide 300°/s angular velocity yes* anterior protrusion maximum 20 mm from top of lamination plate 56 mm (measured with ruler) without the cover59 mm with the cover no lateral protrusion maximum 7.99 cm from centre of lamination plate 7.2 cm (measured with ruler) yes medial protrusion maximum 4.99 cm from centre of lamination plate 4.7 cm (measured with ruler) yes device length maximum 378 mm 347 mm (measured with ruler) yes user safety no uncovered finger traps cover prevents most finger traps cover does not fit over steel cables no * the össur power knee™ microprocessor-controlled motor was used in this prototype, which provides 96 nm of hip torque and an angular velocity of 300°/s. https://doi.org/10.33137/cpoj.v7i2.44494 10 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 during the initial testing, steel cabling was selected due to ease of crimping on terminators. however, steel cables are not ideal for a final product because their rated capacity is 1779 n, which falls below the design criterion tensile strength of 4465 n, posing a risk of failure under increased loads. conclusion the novel microprocessor-controlled php demonstrated successful performance in both mechanical strength and functional testing. the pulley and cable transmission system effectively transmitted power from the actuator to the hip joint, meeting the functional design requirements while maintaining a compact and lightweight profile, showing strong potential for real-world applications. while the php achieved most of its principal design objectives, some areas like part optimization, control system design, and cable strength and slack management require further refinement. future iterations could focus on implementing an intelligent adaptive control system, optimizing mechanical parts and mechanisms, and continuing functional testing with people with hd or hp amputations. at this stage of development, a reasonable balance between comfort and safety has been achieved and will be further refined as development progresses. continued research and development will aim to address the remaining challenges, prioritizing gait stability and symmetry, pushing the technology closer to real-world deployment. acknowledgements the authors would like to thank farshad golshan, and hossein gholizadeh for their work on the powered hip design and control system development, yousef bader for his help with the assembly, and the ottawa hospital rehabilitation centre and the university of ottawa for providing resources for development and testing. they would also like to thank össur staff for their assistance with documentation of the knee joint and electronics. declaration of conflicting interests david langlois is an employee of össur. no other conflicts of interest. authors contribution • kelly brannen: conceptualization; joint design; data collection and analysis; manuscript revision. • natalie baddour: conceptualization; data analysis; manuscript revision, supervision. • lucas cho: prepared the initial manuscript; manuscript revision. • david langlois: conceptualization; design. • patrick dumond: design. • edward lemaire: conceptualization; data analysis; manuscript revision; supervision. sources of support this study was financially supported by össur and mitacs. references 1.kaufman kr, levine ja, brey rh, iverson bk, mccrady sk, padgett dj, et al. gait and balance of transfemoral amputees using passive mechanical and microprocessor-controlled prosthetic knees. gait posture. 2007;26(4):489-93, doi: 10.1016/j.gaitpost.2007.07.011 2.kaufman kr, levine ja, brey rh, mccrady sk, padgett dj, joyner mj. energy expenditure and activity of transfemoral amputees using mechanical and microprocessor-controlled prosthetic knees. arch phys med rehabil. 2008;89(7):1380-1385. doi: 10.1016/j.apmr.2007.11.053 3.waters rl, perry j, antonelli da, hislop h. energy cost of walking of amputees: the influence of level of amputation. j. bone joint surg am. 1976;58(1):42-6 4.ludwigs e, bellmann m, schmalz t, blumentritt s. biomechanical differences between two exoprosthetic hip joint systems during level walking. prosthet orthot int. 2010;34(4):449-60. doi: 10.3109/03093646.2010.499551 5.grimmer m, seyfarth a. mimicking human-like leg function in prosthetic limbs. neuro-robotics: from brain machine interfaces to rehabilitation robotics. 2014:105-55. doi: 10.1007/978-94-0178932-5_5 6.chin t, sawamura s, shiba r, oyabu h, nagakura y, nakagawa a. energy expenditure during walking in amputees after disarticulation of the hip: a microprocessor-controlled swing-phase control knee versus a mechanical-controlled stance-phase control knee. j. bone joint surg br. 2005;87(1):117-9 7.karimi mt, kamali m, omar h, mostmand j. evaluation of gait performance of a hemipelvectomy amputation walking with a canadian prosthesis. case rep orthop. 2014;962980. doi: 10.1155/2014/962980 8.gailey r, allen k, castles j, kucharik j, roeder m. review of secondary physical conditions associated with lower-limb amputation and long-term prosthesis use. j rehabil res dev. 2008;45(1),15–29. doi: 10.1682/jrrd.2006.11.0147 9.fluit r, prinsen ec, wang s, van der kooij h. a comparison of control strategies in commercial and research knee prostheses. ieee trans biomed eng. 2019;67(1):277-90. doi: 10.1109/tbme.2019.2912466 10.dall pm, kerr a. frequency of the sit to stand task: an observational study of free-living adults. appl ergon. 2010;41(1):58-61. doi: 10.1016/j.apergo.2009.04.005 11.ludwigs e, bellmann m, schmalz t, blumentritt s. biomechanical differences between two exoprosthetic hip joint systems during level walking. prosthet orthot int. 2010;34(4):44960. doi: 10.3109/03093646.2010.499551 12.ueyama y, kubo t, shibata m. robotic hip-disarticulation prosthesis: evaluation of prosthetic gaits in a non-amputee individual. adv robot. 2020;34(1):37-44. doi: 10.1080/01691864.2019.1705908 https://doi.org/10.33137/cpoj.v7i2.44494 11 brannen k, baddour n, cho l, langlois d, dumond p, lemaire e.d. development and evaluation of an anteriorly mounted microprocessor-controlled powered hip joint prosthesis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 7. https://doi.org/10.33137/cpoj.v7i2.44494 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor-controlled powered hip joint prosthesis brannen et al., 2024 13.mroz s, baddour n, dumond p, lemaire ed. design and prototype validation of a laterally mounted powered hip joint prothesis. j rehabil assist technol eng. 2024;11. doi: 10.1177/20556683241248584 14.bader y, langlois d, baddour n, lemaire ed. development of an integrated powered hip and microprocessor-controlled knee for a hip–knee–ankle–foot prosthesis. bioeng. 2023;10(5):614. doi: 10.3390/bioengineering10050614 15.bona rl, gomeñuka na, storniolo jl, bonezi a, biancardi cm. self-selected walking speed in individuals with transfemoral amputation: recovery, economy and rehabilitation index. eur j physiother. 2020;22(3):133-40. doi: 10.1080/21679169.2018. 1561941 16.darter bj, nielsen dh, yack hj, janz kf. home-based treadmill training to improve gait performance in persons with a chronic transfemoral amputation. arch phys med rehabil. 2013;94(12):2440-7. doi: 10.1016/j.apmr.2013.08.001 17.schmalz t, blumentritt s, marx b. biomechanical analysis of stair ambulation in lower limb amputees. gait posture. 2007;25(2):267-78. doi: 10.1016/j.gaitpost.2006.04.008 18.segal ad, orendurff ms, klute gk, mcdowell ml, pecoraro ja, shofer j, et al. kinematic and kinetic comparisons of transfemoral amputee gait using c-leg and mauch sns prosthetic knees. j rehabil res dev. 2006;43(7). doi: 10.1682/jrrd.2005.09.0147 19.össur. power knee pka01: instructions for use [internet]. [cited 2024 dec 10]. available from: https://ossur.com.ua/media/ossur/instructions/brochures/knee/po wer%20knee%20instructions%20for%20use.pdf 20.iso 15032:2000. prostheses – structural testing of hip joints [internet]. 2000 [cited 2024 dec 10]. available from: https://webstore.ansi.org/standards/bsi/bsiso150322000 21.gordon cc. 1988 anthropometric survey of us army personnel: methods and summary statistics. technical report natick/tr89/044. 1989. http://mreed.umtri.umich.edu/mreed/downloads/anthro/ansur/gord on_1989.pdf 22.brannen k. design and evaluation of a microprocessorcontrolled powered hip prosthesis [master's thesis]. ottawa (on): university of ottawa; 2023 23.fanous a, botros m, gholizadeh h, baddour n, lemaire ed. design and evaluation of a hip prosthesis simulator: a technical note. prosthet orthot int. 2023;4,443–446. doi: 10.1097/pxr. 0000000000000208 https://doi.org/10.33137/cpoj.v7i2.44494 https://ossur.com.ua/media/ossur/instructions/brochures/knee/power%20knee%20instructions%20for%20use.pdf https://ossur.com.ua/media/ossur/instructions/brochures/knee/power%20knee%20instructions%20for%20use.pdf https://webstore.ansi.org/standards/bsi/bsiso150322000 http://mreed.umtri.umich.edu/mreed/downloads/anthro/ansur/gordon_1989.pdf http://mreed.umtri.umich.edu/mreed/downloads/anthro/ansur/gordon_1989.pdf all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 1 2022 research article brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-footorthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i1.37795 1 brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 research article experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-anklefoot orthoses (mp-sscos) brüggenjürgen b.1*, braatz f.2, greitemann b.3, drewitz h.4, ruetz a.5, schäfer m.6, seifert w.7, steinfeldt f.8, weichold c.9, yao d.10, stukenborg-colsman c.10 1 institute for health services research and technical orthopedics, orthopedic department medical school hannover (mhh) at diakovere annastift hospital, hannover, germany. 2 klinik für unfallchirurgie, orthopädie und plastische chirurgie universitätsmedizin göttingen, georg-august-universität, göttingen, germany. 3 rehaklinikum bad rothenfelde, klinik münsterland, bad rothenfelde, germany. 4 abteilung orthetik, otto bock healthcare deutschland gmbh,göttingen, germany. 5 klinik für konservative orthopädie, katholisches klinikum koblenz, montabaur, germany. 6 orthopädie-technik, pohlig gmbh, traunstein, germany. 7 technische orthopädie, seifert technische orthopädie gmbh, bad krozingen, germany. 8 fachklinik und gesundheitszentrum, johannesbad raupennest gmbh & co. kg, altenberg, germany. 9 technische orthopädie, stiftung orthopädische universitätsklinikum, heidelberg, germany. 10 foot department and technical orthopedics, orthopedic department medical school hannover (mhh) at diakovere annastift hospital, hannover, germany. open access volume 5, issue 1, article no.7. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract background: patients with neuromuscular knee-instability assisted with orthotic devices experience problems including pain, falls, mobility issues and limited engagement in daily activities. objectives: the aim of this study was to analyse current real-life burden, needs and orthotic device outcomes in patients in need for advanced orthotic knee-ankle-foot-orthoses (kafos). methodology: an observer-based semi-structured telephone interview with orthotic care experts in germany was applied. interviews were transcribed and content-analysed. quantitative questions were analysed descriptively. findings: clinical experts from eight centres which delivered an average of 49.9 kafos per year and 13.3 microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos) since product availability participated. reported underlying conditions comprised incomplete paraplegia (18%), peripheral nerve lesions (20%), poliomyelitis (41%), post-traumatic lesions (8%) and other disorders (13%). the leading observed patient burdens were “restriction of mobility” (n=6), followed by “emotional strain” (n=5) and “impaired gait pattern” (n=4). corresponding results for potential patient benefits were seen in “improved quality-of-life” (n=8) as well as “improved gait pattern” (n=8) followed by “high reliability of the orthosis” (n=7). in total, experts reported falls occurring in 71.5% of patients at a combined annual frequency of 7.0 fall events per year when using kafos or stance control orthoses (scos). in contrast, falls were observed in only 7.2 % of mpssco users. conclusion: advanced orthotic technology might contribute to better quality of life of patients, improved gait pattern and perceived reliability of orthosis. in terms of safety a substantial decrease in frequency of falls was observed when comparing kafo and mp-ssco users. article info received: november 24, 2021 accepted: february 10, 2022 published: february 25, 2022 citation brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-andswing-phase-controlled-knee-anklefoot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7.https://doi.org/10.33137/cpoj.v5i 1.37795 keywords knee instability, ankle foot orthoses, kafo, microprocessor orthoses, mp-sccos, poliomyelitis, patient burden, quality of life, survey * corresponding author prof. dr. med. bernd brüggenjürgen head institute health services research and technical orthopedics, orthopedic department medical school hannover (mhh) at diakovere annastift hospital, anna-vonborries-str. 1-7, 30625 hannover, germany. e-mail: brueggenjuergen.bernd@mh-hannover.de orcid id: https://orcid.org/0000-0002-8866-0809 https://doi.org/10.33137/cpoj.v5i1.37795 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i1.37795 https://doi.org/10.33137/cpoj.v5i1.37795 mailto:brueggenjuergen.bernd@mh-hannover.de https://orcid.org/0000-0002-8866-0809 2 brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 issn: 2561-987x experts’ perceived patient burden and outcomes of kafos vs. mp-sscos brüggenjürgen et al., 2022 cpoj introduction orthotic devices, in particular knee-ankle-foot-orthoses (kafos) are well accepted for treating knee instability in neuromuscular disease and central nervous system conditions. however, burden of disease and individual demands of patients have been rarely studied. knee instability conditions can cause several problems, including pain, falls, range of mobility issues and limited engagement in daily activities, which could be alleviated with the use of better orthotic devices.1,2 a kafo is usually prescribed when other types of bracing like ankle-foot-orthoses (afo) cannot adequately control knee instability because of weakness (e.g., quadriceps weakness) or ligament laxity.3 patients suffering from knee instability due to neuromuscular disease (e.g., after acute poliomyelitis, incomplete spinal cord injury, or femoral nerve lesions), benefit from kafos with locked or posterior off-set orthotic knee joints by preventing the paretic or paralyzed leg from collapsing and to aid in safe ambulation.2,4 however, a locked knee precludes knee flexion during swing and, thus, requires compensatory mechanisms to achieve sufficient toe clearance.2 stance control orthoses (sco) allow users to flex their knee during the swing phase to reduce the compensations of hip hiking and circumduction. however, these benefits are mostly limited to walking on level surfaces, because the difficulty to relock the orthotic knee joint on non-level terrains results in limitations in function and safety for walking on uneven terrain, stairs, ramps, or with varying speed.4-6 in particular, patients’ limited ability to walk and maintain conditioning results in a high risk of falling due to deconditioned coordination and balance.1 a microprocessor-swing-and-stance-controlled knee-anklefoot-orthosis (mp-ssco) provide both swing and stance phase control for patients suffering from paralysis or paresis of the muscles that stabilize the knee. c-brace (ottobock, duderstadt, germany) is the only mp-ssco currently holding a market authorization in the us and the european union. the microprocessor control enables dampening of knee flexion during weight-bearing and speed-adapted control of knee flexion and extension during the swing phase.7 this feature enhances patients’ confidence in knee joint function, increased walking speed and energy efficiency, and improved safety for walking on uneven terrain, stairs, and ramps.8 limited published data could only be obtained for one other microprocessor-controlled orthosis type, a microprocessor-controlled-stancecontrolled orthosis (mp-sco).9 independence for individuals with lower limb motor disabilities is a key issue in their daily routine and can be enhanced with the use of assistive devices to promote their participation in social activities and in living a self-sufficient life.10 hence, the key issue in orthotic care is utilizing the appropriate orthosis (kafo or mp-ssco) to address users’ needs and expectations.11-13 furthermore, real-life settings are difficult to scrutinize due to the multitude of underlying disease states as well as different settings and patients’ behaviors that complicates pragmatic real-life trials. aim of this study was to analyse the current real-life burden of patients in need for advanced orthotic kafos, their needs and patient relevant outcomes as well as the potential benefit of a mp-ssco on patient outcomes and care processes. methodology system instrumentation an observer-based semi-structured interview survey with experts in the field of kafo/mp-ssco fitting was used. expert participants were selected based on a) meeting orthotic clinical and technical care expertise qualifications (both physicians and orthotists) and b) having been involved in orthotic care for more than 5 years both with kafos as well as mp-ssco in a german orthotic care centre. furthermore, participants were only selected, if willingness to devote time and interest to the specific topic was stated, as well as informed consent to participate was provided. as this survey was neither a notifiable clinical study according to §47 par. 3 mdpg nor an epidemiologic study with individual patient reference an ethics committee vote did not apply. semi-structured interviews are employed in qualitative interview research where the order and content of questions in an interview can be modified to deepen the exploration of a research topic according to the response of the interviewee.14 the interviews were conducted by phone and survey questions were comprised of the following areas: participants’ orthotic experience, challenges in orthotic rehabilitation, patient burden and severity of this burden, patient needs and benefits, patient relevant outcomes, rehabilitation under delivery of new orthotic devices, severity and frequency of falls, adverse events other than falls. queries were phrased using mp-ssco as the product group term with c-brace (otto bock, duderstadt, germany) being presented to the interviewees as an example once or on request. the information collected in the interviews was transcribed and was prepared for a content analysis. content analysis is described as a method to classify written or oral materials into identified categories of similar meanings.15 the analytic process of the qualitative interview component approximated the following steps: determination of category and levels of abstraction, the development of inductive categories from material, the revision of categories, the final https://doi.org/10.33137/cpoj.v5i1.37795 https://www.ottobockus.com/media/local-media/c-brace-may-2020-campaign/c-brace-ifu.pdf https://www.ottobock.com/en/ https://www.ottobock.com/en/ 3 brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 issn: 2561-987x experts’ perceived patient burden and outcomes of kafos vs. mp-sscos brüggenjürgen et al., 2022 cpoj working through text, and the interpretation of results.16 quantitative questions were reported with descriptive statistics. results eight clinical experts confirmed participation in the semistructured telephone interview lasting approximately one hour in duration. interviews were performed from 2020-1109 to 2021-02-03. all participants (7 male, 1 female; 4 physicians and 4 orthotists) had long-term experience in prescribing, fitting, and delivering acute as well as subacute and chronic rehabilitation care both for kafos and mpssco users. on average, experts’ centres prescribed or delivered 49.9 kafos per year and 13.3 mp-sscos (cbrace only) since product availability to patients. the treated population is comprised of patients with incomplete paraplegia (18%), peripheral nerve lesions (20%), poliomyelitis (41%), posttraumatic lesions (8%) and other disorders, including stroke sequelae (13%). challenges in orthotic rehabilitation half of the experts (n=4) considered a correct indication and diagnosis as a key challenge for patient rehabilitation in orthotic care, and in particular for mp-ssco: 38% emphasized the need for intensive patient support and guidance, especially for understanding and using the functionality of the orthosis. a safe stance phase, safe handling by the patient and a well-fitting orthosis with proper alignment of the components as well as the challenges in approaching reimbursement bodies were mentioned by two interviewees. categories reported once only were: standardized assessments for orthosis selection, risk of falling due to stiff knee, foot clearance, dressing/undressing in daily routine, early integration of orthosis into therapy and training, gap between technical feasibility and return to full participation in real life as well as a need towards an interdisciplinary approach. regarding structure and process of rehabilitation, 7 out of 8 of the interviewees observed a relevant change when switching to mp-ssco. changes were mentioned in particular with regard to a more intensified initial education phase in mp-ssco patients (57% of those reporting change) as the understanding of the orthosis’ potential was considered essential (43%). despite the intensity of early rehabilitation activities, a shorter overall process was reported (57%). seven interviewees reported several extraordinary case reports, such as a female, middle-aged, still active teacher with a lower limb amputation on the contralateral side and a substantial paralysis on the supplied side being instantly able to return to independent ambulation. a further example provided was a young, female patient with a complete femoralis paresis after polytrauma suffering extremely from abrupt cessation of her active life who was able to return to independent ambulation with the committed support of the centre’s team. categories of extraordinary cases could be categorized as unexpected regain of mobility and ambulation, return to ambulation without crutches, possibility of fitting an orthosis in difficult posttraumatic situations where orthotic care had been unavailable previously, and cases of fully unexpected clinical benefit and occupational rehabilitation. patient burden in terms of expert-observed burden on patients due to impairment, “restriction of mobility” ranked highest among the queried three most serious items (n=6), followed by “emotional strain” (n=5) as these patients often suffer from severe progressive and/or continuously deteriorating conditions with multiple comorbidities. the third item was “impaired gait pattern” (n=4), including “lack of symmetry” and “negative impact on full social participation”, exemplified by one interviewee as issues with the aesthetic appearance (both n=4). further impairments observed were “extension contractures or flexion restrictions”, “painful conditions”, “impaired climbing of stairs” and “lack of postural control”, as those patients may have impaired stability and/or not have the ability to stand (n=2). (figure 1) for those serious impairment items reported at least by two experts, “impaired climbing of stairs” obtained the highest observed frequency followed by “restriction of mobility”, “lack of postural control”, “restricted participation”, impaired gait”, and “emotional strain”. “pain” and “contracture” were reported sometimes or rarely with regard to frequency. (figure 2) potential patient benefits experts judged “quality of life” of patients (n=8) as well as “improved gait pattern” (n=8), followed by “high reliability of the orthosis” (n=7) as the most relevant domains of potential patients’ benefits from optimal delivery of orthotic care. “patient satisfaction”, “personal autonomy” and “reduction in compensatory mechanisms” were reported as relevant by six experts. the items “ability to perform daily routine”, “wearing comfort” and “higher velocity” obtained a frequency of five reports. (figure 3) when valuing each benefit’s importance to patients and selecting the three most relevant aspects, “perception of safety and high stability while walking” ranked highest (n=5), followed by “physiologic gait” (n=4) and the ability for “participation in daily life” (n=3). “not having to think about the orthosis”, i.e., no need for conscious orthotic control, “prevention of falls”, “mobility” and “ability to swing” were seen by two experts amongst the three top-ranking domains of patient need. (figure 3) https://doi.org/10.33137/cpoj.v5i1.37795 4 brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 issn: 2561-987x experts’ perceived patient burden and outcomes of kafos vs. mp-sscos brüggenjürgen et al., 2022 cpoj figure 1: patient impairments and burden as perceived by experts 0 1 2 3 4 5 6 restriction of mobility emotional strain impaired gait restricted participation contracture pain impaired climbing of stairs missing postural control cosmetic appearance lumbar impairment strain contralateral side muscle weakness length difference lymphatic drain incontinence job loss changing clothes imminent fall frequency of responses (n) patient impairments and burden as perceived by experts 0 10 20 30 40 50 60 70 80 90 100 impaired climbing of stairs restriction of mobility missing postural control restricted participation impaired gait emotional strain pain contracture expert-observed frequency of impairments’ figure 2: expert-observed frequency of impairments (reported more than one time). categories (always, often, sometimes, seldom, never) were transferred to 0-100-scale with 100 representing the highest frequency “always”. https://doi.org/10.33137/cpoj.v5i1.37795 5 brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 issn: 2561-987x experts’ perceived patient burden and outcomes of kafos vs. mp-sscos brüggenjürgen et al., 2022 cpoj figure 3: reported expert-perceived patient benefits. figure 4: relevance of suggested patient assessment criteria. 0 2 4 6 8 10 12 14 reported expert-perceived patient benefits response importance response frequency 0 1 2 3 4 5 6 gait analysis number of falls participation walking distance time up and go quality of life wearing comfort gait feeling in daily routine need for additional medical aid frequency of responses patient relevant outcomes criteria f re q u e n c y o f r e s p o n s e s ( n ) https://doi.org/10.33137/cpoj.v5i1.37795 6 brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 issn: 2561-987x experts’ perceived patient burden and outcomes of kafos vs. mp-sscos brüggenjürgen et al., 2022 cpoj outcomes assessment in orthotic device alignment furthermore, experts provided suggestions to implement specific tools for patients’ assessment in clinical routine covering both patient-relevant orthotic-device related outcomes as well as quality assurance aspects. in this context, “gait analysis”, e.g. via video, was reported most often with high relevance (n=5), followed by “number of falls in patient history” (n=4), “participation” and “walking distance” (n=3). (figure 4) orthosis-specific safety and long-term outcomes frequency of falls and resource use kafo when using kafos or stance control orthoses without microprocessor control (scos), falls were estimated to occur once weekly (standard deviation (sd) 0.0) in 4.0 % (sd=9.9) of patients. monthly falls were seen in 23.8% (sd= 28.3) and annual falls in 43.8% (sd=30.0) of patients with a frequency of 1.25 (sd=0.9) and 3.19 (sd=1.5), respectively. in total, falls were reported to occur in 71.5% of patients at a combined annual frequency of 7.0 fall events per year when using kafos or scos. serious falls may result in the need for medical care. healthcare resource use related to falls with nonmicroprocessor-controlled knees (non-mpks) was estimated to require hospital care in 4.0% (sd=3.7) and non-hospital medical care in the out-patient setting in 19.3% of fall cases (sd=17.5). 76.7% (sd=20.1) of total falls were considered not to require any health professional care. long-term consequences wearing kafos and scos is associated with both adverse effects and long-term consequences. adverse effects include “excessive lumbar loading with lack of trunk stability” (n=3), “impairment of gait” (n=2) and “stiff limb”, “rollator dependency”, “fitting problems”, “risk of luxation in hip replacement patients” and “noise” which were each reported only once. regarding long-term consequences, most experts considered “lumbar disorders with a locked knee joint” (n=4) as the most relevant item, followed by figure 5: observed long-term consequences (primary axis: number of experts reporting, secondary axis: transposed frequency of consequences in percent of time occurring categories (always, often, sometimes, seldom, never) were transferred to 0100-scale with 100 representing the highest frequency “always”.) 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 observed long-term consequences number of experts' entries frequency of long-term consequences https://doi.org/10.33137/cpoj.v5i1.37795 7 brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 issn: 2561-987x experts’ perceived patient burden and outcomes of kafos vs. mp-sscos brüggenjürgen et al., 2022 cpoj “muscular atrophy” (n=3). “orthosis cut-out oedema”, “scrub marks” and “degenerative impact” were reported being relevant by two experts. “pelvic adverse effects”, “mental burden”, “physical discomfort due to forearm crutches”, “contractures”, “pain” and “hyperlordosis / scoliosis” were reported as relevant by one expert each. “scrub marks” were reported both as adverse effect and long-term consequence. all long-term consequences were considered to occur “always” to “sometimes” in frequency (figure 5). frequency of falls and experiences with mpk fitting experts termed orthotic care with an mp-scco as outstanding only when patients benefitted considerably in real life settings (following a sound trial fitting), despite ambiguous diagnostic results during the initial assessment (n=4). further outstanding experts’ experiences were successful fitting of orthosis in complex post-traumatic and postoperative situations (n=3) and the regain of mobility in the patients´ daily routine (n=2). the frequency of falls in mp-scco users was estimated on an annual basis. falls were observed to occur in 7.2 % (sd=10.3) of all patients with an annual frequency of 2.2 (sd=3.0) fall events per year. discussion burden of patients in need of kafos was analysed with an experts’-based interview survey. restriction of mobility, emotional strain and impaired gait were reported as major impairment aspects. potential for improving care in patients who use non-microprocessor-controlled kafos is seen in particular with regard to quality of life (qol), gait, and reliability of the orthosis. the experts underscored the importance of appropriate outcomes assessment criteria, such as gait analysis, orthosis safety (prevention of falls), and participation in activities of daily living. in terms of frequency of falls, a substantial difference between nonmicroprocessor-controlled kafos and mp-sscos was reported. in our study improved gait pattern, qol and high reliability of the orthosis were most often reported as important outcomes to patients. this is largely in line with health care professional (hcp) estimates reported by o’connor et al., where comfort, confidence in mobility and increased stability were most often reported as being very or extremely important to patients.1 though qol in our study was most frequently stated as a relevant patient benefit of optimal orthotic care, no expert valued qol or patient satisfaction amongst the three most important domains. this lack of perceived high importance might be due to the fact that qol comprises different physical and psychological domains of health-related qol and, hence, results in an improvement, if a majority of other aspects of benefit have been achieved. adding to this line of reasoning is the fact that retraining of compensatory gait patterns, such as circumduction, requires time and, hence, may delay an early, straightforward improvement in qol.17 furthermore, the reported experts’ perception might be influenced by the german healthcare reimbursement decision making process, where qol has just recently gained more importance. unlike yang et al., we conducted interviews with experts caring for patients in need for lower limb orthoses.10 however, despite not directly involving patients’ responses, research of health-related qol did show that the results obtained from attending hcps considerably overlap with patients’ individual feedback, resulting in reasonable agreement that make the hcps’ perception a valuable source of assessment.18 however, when assessing individual patients, there was some discordance between scores obtained from hcps compared to patients, with physicians systematically underestimating overall qol, social functioning, and role functioning. interestingly, patients in the uk expected the orthotic device to foremost enable them to engage in ‘normal’ daily activities and taking part in social events and gatherings which represent relevant qol domains.1 hence, demands and potential benefits of mp-sscos in domains such as participation, mental well-being and qol reported by hcps in our study might be underestimated. yang et al. reported that patients with neurologic conditions are mostly interested in restoring both walking and standing, whereas patients with musculoskeletal injuries had a single focus on normal walking.10 problems of orthosis use related to normal walking in patients with damage to the nervous system were mentioned mostly with regard to restricted mobility, skin injury due to excessive rubbing, orthosis durability and material-related issues. for those focusing on standing, material-related issues dominated. problems in orthosis use by patients with musculoskeletal injuries were restricted mobility and material-related issues.10 the post-fall syndrome (depression, fear of falling and other psychological problems) is a common consequence of repeated falls, with up to 40% of patients not reporting recent falls and up to 70% of recent fallers reporting fear of falling.19 loss of self-confidence as well as social withdrawal, confusion and loneliness can occur, even if there has been no injury. reduced physical and functional activity is associated with fear and anxiety of falling strong correlations have been found between fear and poor postural performance.20 hence, the reported reduction in fall rate in our study indicates the potential for improved selfconfidence and better qol with a mp-ssco. our results underline the need for proper alignment of orthosis components to reflect the individual patients’ anatomy. this is in line with yang et al. as their results show that users with the same symptoms may use different https://doi.org/10.33137/cpoj.v5i1.37795 8 brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 issn: 2561-987x experts’ perceived patient burden and outcomes of kafos vs. mp-sscos brüggenjürgen et al., 2022 cpoj orthoses.10 our results confirm the need for incorporating patient relevant outcomes in real-life settings into highquality research of orthotic devices for knee instability related to neuromuscular and central nervous system conditions.3 study limitations: despite having interviewed experts with different expertise and professional backgrounds, the low number of interviewees might contribute to potential bias. however, in germany, there are only a few expert centres experienced both in treating and fitting patients with muscular knee instability and mp-ssco fitting, resulting in an appropriate representation of centres’ experience. furthermore, the fact that results were obtained from a health care professionals’ point of view might have led to different perceptions compared to direct patient interviews or surveys. while formerly hcp-derived patient information was perceived to be superior to those collected from studied subjects,21 more recently patient self-reported outcomes are considered as an equally valuable contribution in the health sciences, where interviewer and physician assessments are understood to be complementary to selfassessed health measures.22,23 furthermore, studies showed that results obtained from hcps consistently underrate the positive impact on mental well-being and hence experts’ estimates might serve as conservative estimate of patients’ outcomes and needs.18 conclusion patients with muscular knee instability following neuromuscular or central nervous system injuries or conditions who use kafos/scos are suffering from restricted mobility, emotional strain and impaired gait patterns. advanced orthotic technology might contribute to better qol of patients, improved gait patterns with subsequent reduction of long-term consequences and perceived reliability of the orthosis. in terms of safety, a substantial decrease in the frequency of falls with mpssco compared to non-microprocessor-controlled kafos was reported. advanced orthotic devices may enhance physical and psychological health and well-being by enabling patients to pursue their daily routines. in selected patients who are unable to be fitted with nonmicroprocessor-controlled kafo/sco, mobility might be regained through mp-sscos with the additional benefit of spending less time in a wheelchair or even discontinuing its use. advanced orthoses require even more interdisciplinary rehabilitation with a standardized outcomes assessment comprising instruments for gait analysis and assessing the number of falls as well as individual participation in activities of daily living. acknowledgements no assistance in the preparation of this article is to be declared. declaration of conflicting interests bernd brüggenjürgen, frank braatz, bernhard greitemann, axel ruetz, friedemann steinfeldt, daiwei yao, and christina stukenborg-colsman received lecture fees; heiko drewitz is an employee of otto bock; michael schäfer, wolfgang seifert have collaborations with the sponsor. claudia weichold none to be declared. author contribution bernd brüggenjürgen: conception and design, analysis and drafting of the paper, interpretation of the data; revising it critically for intellectual content and final approval of the version to be published. frank braatz, bernhard greitemann, heiko drewitz, axel ruetz, michael schäfer, wolfgang seifert, friedemann steinfeldt, claudia weichold, daiwei yao, christina stukenborg-colsman: interpretation of the data; revising it critically for intellectual content and final approval of the version to be published. sources of support this work was supported by a grant of otto bock healthcare products gmbh, wien. ethical approval expert participants were only selected, if willingness to devote time and interest to the specific topic was stated, as well as informed consent to participate was provided. as this survey was neither a notifiable clinical study according to §47 par. 3 mdpg nor an epidemiologic study with individual patient reference, an ethics committee vote did not apply. references 1.o'connor j, mccaughan d, mcdaid c, booth a, fayter d, rodriguez-lopez r, et al. orthotic management of instability of the knee related to neuromuscular and central nervous system disorders: systematic review, qualitative study, survey and costing analysis. health technology assessment. 2016;20(55):1-262. doi: 10.3310/hta20550 2.fox jr, lovegreen w. 22 lower limb orthoses. in: webster jb, murphy dp, editors. atlas of orthoses and assistive devices (fifth edition). philadelphia: elsevier; 2019; 239-46.e1. 3.mcdaid c, fayter d, booth a, o'connor j, rodriguez-lopez r, mccaughan d, et al. systematic review of the evidence on orthotic devices for the management of knee instability related to neuromuscular and central nervous system disorders. bmj open. 2017;7(9):e015927. doi: 10.1136/bmjopen-2017-015927 4.probsting e, kannenberg a, zacharias b. safety and walking ability of kafo users with the c-brace((r)) orthotronic mobility https://doi.org/10.33137/cpoj.v5i1.37795 9 brüggenjürgen b., braatz f., greitemann b., drewitz h., ruetz a., schäfer m., et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stance-and-swing-phase-controlled-knee-ankle-foot orthoses (mp-sscos). canadian prosthetics & orthotics journal. 2022; volume 5, issue 1, no.7. https://doi.org/10.33137/cpoj.v5i1.37795 issn: 2561-987x experts’ perceived patient burden and outcomes of kafos vs. mp-sscos brüggenjürgen et al., 2022 cpoj system, a new microprocessor stance and swing control orthosis. prosthet orthot int. 2017;41(1):65-77. doi: 10.1177/ 0309364616637954 5.arazpour m, ahmadi f, bani ma, hutchins sw, bahramizadeh m, ghomshe ft, et al. gait evaluation of new powered knee-anklefoot orthosis in able-bodied persons: a pilot study. prosthet orthot int. 2014;38(1):39-45. doi: 10.1177/0309364613486917 6.tian f, hefzy ms, elahinia m. state of the art review of knee– ankle–foot orthoses. ann biomed eng. 2015;43(2):427-41. doi: 10.1007/s10439-014-1217-z 7.deems-dluhy s, hoppe-ludwig s, mummidisetty ck, semik p, heinemann aw, jayaraman a. microprocessor controlled knee ankle foot orthosis (kafo) vs stance control vs locked kafo: a randomized controlled trial. arch phys med rehabil. 2021;102(2):233-44. doi: 10.1016/j.apmr.2020.08.013 8.schmalz t, pröbsting e, auberger r, siewert g. a functional comparison of conventional knee–ankle–foot orthoses and a microprocessor-controlled leg orthosis system based on biomechanical parameters. prosthet orthot int. 2016;40(2):277-86. doi: 10.1177/0309364614546524 9.daines kjf, farah j, baddour n, duke c, bhatti j, lemaire ed. preliminary kinematic and kinetic evaluation of a modular microprocessor-controlled stance-control knee-ankle-foot orthosis. cmbes proceedings. 2019;42(0). 10.yang bs, chen yw, tong jr. user experience of lower-limb orthosis. assist technol. 2018;30(5):267-73. doi: 10.1080/ 10400435.2017.1322157 11.borsci s, londei a, federici s. the bootstrap discovery behaviour (bdb): a new outlook on usability evaluation. cogn process. 2011;12(1):23-31. 12.ravneberg b. usability and abandonment of assistive technology. j assist technol. 2012;6(4):259-69. doi:10.1108/ 17549451211285753 13.söderström s, ytterhus b. the use and non‐use of assistive technologies from the world of information and communication technology by visually impaired young people: a walk on the tightrope of peer inclusion. disabil soc. 2010;25(3):303-15. doi:10.1080/09687591003701215 14.klandermans b, staggenborg s. methods of social movement research. boston: university of minnesota press; 2002. 15.moretti f, van vliet l, bensing j, deledda g, mazzi m, rimondini m, et al. a standardized approach to qualitative content analysis of focus group discussions from different countries. patient educ couns. 2011;82(3):420-8. doi: 10.1016/j.pec.2011.01.005 16.cho jy, lee e-h. reducing confusion about grounded theory and qualitative content analysis: similarities and differences. qual rep. 2014; 19. doi:10.46743/2160-3715/2014.1028 17.santer j, macdonald s, rizzone k, biehler s, beiswenger t. strategies for gait retraining in a collegiate runner with transfemoral amputation: a case report. int j sports phys ther. 2021;16(3):8629. doi: 10.26603/001c.23671 18.wilson ka, dowling aj, abdolell m, tannock if. perception of quality of life by patients, partners and treating physicians. qual life res. 2000;9(9):1041-52. doi: 10.1023/a:1016647407161 19.tinetti me, mendes de leon cf, doucette jt, baker di. fear of falling and fall-related efficacy in relationship to functioning among community-living elders. j gerontol. 1994;49(3):m140-7. doi: 10.1093/geronj/49.3.m140 20.maki be, holliday pj, topper ak. fear of falling and postural performance in the elderly. j gerontol. 1991;46(4):m123-31. doi: 10.1093/geronj/46.4.m123 21.kriegsman dm, penninx bw, van eijk jt, boeke aj, deeg dj. self-reports and general practitioner information on the presence of chronic diseases in community dwelling elderly. a study on the accuracy of patients' self-reports and on determinants of inaccuracy. j clin epidemiol. 1996;49(12):1407-17. doi: 10.1016/s0895-4356(96)00274-0 22.ferraro kf, su yp. physician-evaluated and self-reported morbidity for predicting disability. am j public health. 2000; 90(1):103-8. doi: 10.2105/ajph.90.1.103 23.smith kv, goldman n. measuring health status: self-, interviewer, and physician reports of overall health. j aging health. 2011;23(2):242-66. doi: 10.1177/0898264310383421 https://doi.org/10.33137/cpoj.v5i1.37795 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 1 2025 research article alhuzaymi a, fiedler g. exploring the correlation between gait speed and balance in limb prosthesis users: a pilot study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 8. doi:10.33137/cpoj.v8i1.45517 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i1.45517 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 alhuzaymi a, fiedler g. exploring the correlation between gait speed and balance in limb prosthesis users: a pilot study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 8. doi:10.33137/cpoj.v8i1.45517 research article exploring the correlation between gait speed and balance in limb prosthesis users: a pilot study alhuzaymi a1,2, fiedler g2* 1. department of physical therapy, majmaah university, saudi arabia. 2. department of rehabilitation science and technology, university of pittsburgh, usa. introduction it is estimated that 185,000 individuals in the u.s. undergo amputation each year, with the majority of cases attributed to diabetes and peripheral vascular disease.1,2 limb loss can also result from traumatic injuries, including motor vehicle accidents, combat injuries, and work-related accidents.3,4 the removal of cancerous tissues or the treatment of certain congenital deformities may result in amputation as well.5,6 as an irreversible impairment of the patient’s physical integrity, limb loss poses numerous challenges to activities of daily living, including participation in society and gainful employment. postural control, for example, is a critical skill for sustaining everyday activities. balance is the capacity to realign the center of mass within its base of support to maintain stability. horak7 proposed that maintaining postural balance depends on six key sub-components: biomechanical constraints, movement strategies, sensory strategies, spatial orientation, dynamic control, and cognitive processing. losing a limb alters both the weight distribution within the body and the individual’s capacity to maintain equilibrium by adjusting body movement.7,8 in addition, there may be limb-loss related comorbidities that increase a patient’s fall risk. lower limb amputation surgery and subsequently reduced mobility are associated with high levels of mortality9 and morbidity rates, including a higher risk of developing coronary artery disease10 and elevated risk of psychiatric disorders.11 individuals with limb loss may have limited walking ability, which is known to open access abstract background: increasing balance and stability, along with efficient locomotion, is a high-priority goal of physical rehabilitation after limb loss in order to facilitate effective participation in society. research in the general population suggests that the ability to walk fast is correlated to good performance in balance tests. however, it is unclear if and how prosthesis use influences this correlation. objective: our small-sample pilot study aimed to explore whether the general relationship between walking speed and balance holds true for people with limb loss whose physical capabilities are inevitably influenced by their prosthetic devices. methodology: participants with any level of limb loss were recruited and asked to perform the ten-meter walk test and narrowing beam walking test. scores in both tests were analyzed using spearman’s rank correlation coefficient. findings: the initial sample of eleven participants was reduced to eight (5 males, 3 females, mean age 52 years, mean height 171 cm, mean weight 68 kg, mean bmi 23, limb loss levels ranging from partial hand to trans-femoral amputation) after removing outliers. the mean ten-meter walking velocity was 1.16 m/s, and the mean narrowing beam test score was 11.38. the results indicate a medium to strong correlation between fast walking speed and high balance scores (ρ = 0.681, p = 0.063) when outliers are excluded. conclusion: these findings are consistent with prior research conducted in other populations. however, outliers in our data suggest that this relationship is not universal across all individuals with limb loss. possible confounding variables include the activity level and the respectively prescribed prosthetic technology. our finding, that gait speed and balance scores should be evaluated separately to tailor rehabilitation strategies effectively, is preliminary and needs to be confirmed in a larger study. article info received: may 29, 2025 accepted: august 14, 2025 published: august 21, 2025 citation alhuzaymi a, fiedler g. exploring the correlation between gait speed and balance in limb prosthesis users: a pilot study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 8. doi:10.33137/cpoj.v8i1.45 517 keywords limb loss; artificial limbs; gait speed; balance; fall risk; rehabilitation; amputation; prosthesis; velocity. * corresponding author: goeran fiedler, phd affiliation: department of rehabilitation science and technology, university of pittsburgh, usa. e-mail: gfiedler@pitt.edu orcid id: https://orcid.org/0000-0003-1532-1248 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 1, article no. 8. 2025 https://doi.org/10.33137/cpoj.v8i1.45517 https://doi.org/10.33137/cpoj.v8i1.45517 https://doi.org/10.33137/cpoj.v8i1.45517 https://orcid.org/0000-0003-1532-1248 https://jps.library.utoronto.ca/index.php/cpoj/index 2 alhuzaymi a, fiedler g. exploring the correlation between gait speed and balance in limb prosthesis users: a pilot study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 8. doi:10.33137/cpoj.v8i1.45517 canadian prosthetics & orthotics journal issn: 2561-987x gait speed and balance in prosthesis users: a pilot study alhuzaymi a and fiedler g, 2025 correlate with poor balance and may restrict activity and participation.12 a low activity level has been shown to be associated with muscle weakness and impaired joint proprioception.13 gait biomechanics are influenced by both reduced walking speeds and lower levels of physical activity.14,15 post-surgical muscle weakness, after lower or upper limb amputation, may further increase fall risk,2 as may side effects from prescription medication. this often compounds the elevated fall risk that is already typical for old age regardless of limb loss status.4 among the elderly, fear of falling has been reported in between 20% to 46% of nonfallers and 40% to 73% among those who have recently fallen.16-20 by comparison, more than half of individuals with lower limb loss report a minimum of one fall within a year, with roughly about 33% experiencing multiple falls even after completing a comprehensive rehabilitation program.3,21 the research literature demonstrates that walking performance is directly linked with balance.22-27 slow gait speed is recognized as a significant contributor to fall risk, highlighting the need to prioritize the assessment of gait speed in people with limb loss to establish comprehensive data on fall risk factors.28,29 most research has focused on persons with lower limb loss who have been found to have significantly reduced both gait and cognitive performance during single-task testing and even more so during dualtask testing.30 relatively little is known on how upper limb loss affects the relationship between gait speed and balance. furthermore, it is possible that differences in prosthetic hardware affect this relationship. for instance, prosthetic foot/ankle component designs strike a compromise between dynamic efficiency (i.e., gait speed) and static stability (i.e., balance) but cannot be optimized for both at the same time. this raises the question of whether gait speed is as much a generalizable predictor of balance (or vice versa) in people with limb loss as it is in the general population. despite growing awareness of fall risk factors and implementation of prevention strategies, there remains room for improvement in fall prevention programs and their application in the limb loss population.21 assessments of the risk of falls include both subjective and objective measures. common clinical outcome measures include the activitiesspecific balance confidence (abc) scale,31 the berg balance scale (bbs),32 and the narrowing beam walking test (nbwt),33 which have all been found valid and reliable to identify potential risk of falling in individuals with conditions that compromise balance.33-35 the abc has been shown to be limited in distinguishing between persons with a transtibial and transfemoral amputation.35 the bbs has demonstrated a limited capacity to assess the varying degrees of fall risk in persons with lower limb loss.34 the nbwt has been recently introduced as a standardized test designed to assess a wide spectrum of balance capabilities. its unique feature lies in its capacity to pose a significant challenge to those with lower limb loss, thereby providing an effective evaluation of their balance characteristics.33,36,37 while “off-label” uses of the nbwt in other populations may be frequently employed, there is limited research to support its clinical use in individuals with other impairments than lower limb loss. this pilot study aimed to explore the nature of the relationship between walking speed and balance in individuals with both lower and upper limb loss. considering that either limb loss level affects balance, we hypothesized that slower gait speed would be associated with lower nbwt scores, irrespective of the level of amputation or the used prosthetic componentry. methodology a cross-sectional study was conducted to assess the relationship between walking speed and balance in individuals with limb loss. the study was approved by the institutional review board (irb) of the university of pittsburgh. all participants provided informed written consent prior to their involvement in the study. individuals with limb loss were recruited from the institution’s patient registry as well as from local prosthetic clinics. all participants were screened based on the inclusion criteria that required an age of at least 18 years, absence of at least one limb, and the ability to ambulate independently. the inclusion criteria were kept deliberately broad, in accordance with the study’s aim of exploring correlations across the target population, irrespective of the severity of their limb loss. in this context, a more narrowly selected sample would be not only less representative of the population but likely also be too similar in performance to allow for meaningful analysis. potential participants were excluded if they were unable to speak and understand english to follow study instructions, had bilateral lower limb loss, significant sensory or motor neuropathy affecting ambulation, severe visual impairments (e.g., blindness), or any other condition that could affect the validity of the walking assessments. a target sample size of 10 was informed by the purpose of this pilot study to explore whether there may be an unusual correlation of gait speed and balance that warrants further exploration. while limiting generalizability of findings, subjecting only a small sample to the study protocol is ethically motivated and is commensurate with prior research studies in the field.38 given the wide initial inclusion criteria, post-hoc analyses were considered in which the most and/or least physically active participants would be excluded from analysis, in an effort to reduce heterogeneity and focus on the subsample most representative of the majority of people with limb loss. https://doi.org/10.33137/cpoj.v8i1.45517 3 alhuzaymi a, fiedler g. exploring the correlation between gait speed and balance in limb prosthesis users: a pilot study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 8. doi:10.33137/cpoj.v8i1.45517 canadian prosthetics & orthotics journal issn: 2561-987x gait speed and balance in prosthesis users: a pilot study alhuzaymi a and fiedler g, 2025 sociodemographic data, including age, height, weight, and sex, were collected via self-report. prosthetic-related data such as amputation level, amputation etiology, functional (k-) levels, and amputation date were obtained prior to the performance tasks. participants were asked to wear their daily-use prostheses and to complete a 10-meter walk test (10mwt)39 and the nbwt. the 10mwt was performed at preferred gait speed and repeated three times, with the mean of the three trials utilized for scoring purposes. the 10mwt is a common assessment tool used to evaluate gait speed that has a testretest reliability of 0.97 icc.40-43 the nbwt challenges the participants’ balance control by reducing step width. with maximum supervision by the investigator, the participants were instructed to cross their arms and walk along the narrowing beam. the beam is divided into four sections of 1.83 m (6 feet) each for a total length of 7.32 m, where each section has a different width, starting with 18.6 cm, and narrowing down to 8.6 cm, 4.0 cm, and 2.0 cm respectively. the beam is made of 5.0 cm thick boards and is placed on the level floor of the gait lab. the test ends after the participant steps off the beam, uncrosses their arms, or achieves the full length of the beam. the distance traversed on the beam (in feet) is recorded as the test score. the mean of three trials per participant was used for analysis.36,37 to assure safety, participants were closely monitored by study personnel who were positioned close enough to provide support in the event of critical stumbles during the balance trials. normality of the distribution of measurements was evaluated using the shapiro-wilk test. spearman correlation coefficients (ρ) were calculated to analyze the correlation between the nbwt scores and 10mwt walking speeds. spearman correlation is comparably robust against outliers and heavy-tailed distributions44 that are often found in small samples like the one in the present study. cutoff levels for deeming correlations weak (ρ = 0.1), moderate (ρ = 0.3), or strong (ρ = 0.5) were determined in accordance with convention.45 for all analyses, the significance level was set at  = 0.1. the deviation from the more commonly used significance criterion of  = 0.05 is justified by the safety-relevant nature of the variables at play.46 a type-2 error (which is less likely at  = 0.1) would mean missing a clinically significant correlation between gait speed and balance performance, which could lead to treatment decisions (e.g., prosthetic prescriptions) that are less safe by ignoring this relationship. conversely, the consequences of a type-1 error (which is less likely at  = 0.05) are less worrisome (e.g., erroneously prescribing a safer prosthesis option than needed). results a total of 11 participants fit the inclusion criteria and were included in the data collection (table 1). the data (figure 1) showed a mean 10mwt gait speed of 1.17 m/s (sd = 0.40 m/s) and a mean nbwt score of 12.55 (sd = 6.00) across the sample. the correlation between those variables was weak (ρ = 0.259) and not statistically significant (p = 0.442). for a secondary analysis, data were excluded from participants who were deemed outliers unrepresentative of the general amputee population due to their activity level being uncommonly high (along with an unusual amputation level, i.e., a van ness rotationplasty, n = 1) or low (signified by an age of above 70 years, n = 2). in the thus updated sample (n = 8, table 1) the mean 10mwt gait speed was 1.16 m/s (sd = 0.40 m/s) and mean nbwt scores were 11.38 (sd = 5.76). their correlation was classified as moderate to strong (ρ = 0.681) and was significant at the 0.1 level (p = 0.063). table 1: baseline characteristics of participants. variable mean (standard deviation) or count full sample sample with outliers removed age (years) 50 (19.4) 52 (17.4) height (cm) 171 (8.01) 171 (8.3) weight (kg) 75 (4.48) 68 (8.3) male/female ratio 8 / 3 (73% / 27%) 5 / 3 (63% / 37%) bmia 25 (1.15) 23 (2.8) amputation type (no.)b tf (1), tt (4), rp (1), tr (2), th (2), fa (1) tf (1), tt (4), tr (1), th (1), fa (1) years since limb loss 19 (17.02) 21 (12.5) mfcl (k-) level, (no.)c k1 (0), k2 (0), k3 (9), k4 (2) k1 (0), k2 (0), k3 (7), k4 (1) a. bmi indicates body mass index, calculated as weight in kilograms divided by height in meters squared. b. amputation types: tf, transfemoral; tt, transtibial; rp, rotationplasty; tr, transradial; th, transhumeral; fa, finger amputation. c. mfcl indicates medicare functional classification level; k-levels range from k1 to k4. https://doi.org/10.33137/cpoj.v8i1.45517 4 alhuzaymi a, fiedler g. exploring the correlation between gait speed and balance in limb prosthesis users: a pilot study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 8. doi:10.33137/cpoj.v8i1.45517 canadian prosthetics & orthotics journal issn: 2561-987x gait speed and balance in prosthesis users: a pilot study alhuzaymi a and fiedler g, 2025 figure 1: scatter plot of 10mwt velocities (in meters per second) against nbwt scores (distance covered in feet). correlations are shown for the full sample (continuous blue line) and the modified sample without outliers (dashed line). outliers are circled. discussion this work explored the hypothesis that the correlation between gait speed and balance applies to people with limb loss. participants performed the 10mwt and the nbwt to generate the necessary data. our findings suggest that, by trend, participants who took longer to walk 10 meters performed worse in the nbwt, which indicates poorer balance. this does align with previous research that has demonstrated the predictive value of gait speed on fall risk in various populations, albeit using different assessment methods.47-49 this is the first research study that directly correlated walking speed and nbwt scores in people with limb loss. the strength of the observed correlation was limited by the heterogeneity of our full sample, which hints at the more complex relationship between gait speed and balance in users of limb prostheses. one possible factor contributing to this complexity is that the physical performance of people with limb loss largely depends on the prostheses they use, unlike in able-bodied individuals. it is conceivable that, in the case of upper limb loss, the reduced weight of the prosthesis (if one is used at all) compared to the lost arm may pose no disadvantage when it comes to gait speed but could affect the effective response to perturbations of the user’s balance. in lower limb prosthetics, gait speed and balance are influenced by prosthetic design, fit, and alignment. these factors interact differently under varying surface conditions, affecting overall stability.50-52 while analyzing these possible relationships was not within the scope of the pilot data collection, our data may serve as the motivation to further explore them in subsequent work. the outliers in our sample may be explained accordingly. two of our participants combined slow walking speed with relatively high balance scores, while one showed the opposite performance of walking fast but having poor balance. it is possible that their prosthetic design was optimized for balance at the expense of gait speed (or vice versa). while this may have been clinically indicated in these individual cases, we argue that the found compromises may not have been ideal in that they sacrificed one performance measure to benefit another. after excluding the outliers, the correlation between speed and balance increased in strength and was determined to be statistically significant. there are other independent variables that are likely to have an effect on balance and gait speed, such as the participants’ age, cause of limb loss, prosthesis experience, and gender. these could be meaningfully investigated in a larger scale study where the sample size does not prohibit statistical corrections for multiple comparisons. an ad-hoc analysis of our sample showed a trend toward better balance relative to gait speed in individuals with upper limb loss when compared to those with lower limb loss, as indicated by a lower speed/balance ratio. however, the difference was not statistically significant (p = 0.196, cohen’s d = 0.45), leaving it unresolved whether amputation level (upper or lower limb) influences balance relative to gait speed. the clinical relevance of our findings lies in the expanded utility of the nbwt, which may be interpretable beyond its intended use as a balance assessment tool. combining speed and balance tests may offer insights into optimization potential for prosthesis fitting and/or rehabilitation training. somebody may have “too good” balance, if it comes at the expense of walking speed and vice versa. it may be interesting to investigate whether completion time of the nbwt is a meaningful variable in addition to the distance covered. additionally, longitudinal studies could provide insight into whether changes in walking speed over time predict corresponding changes in nbwt performance, promising a deeper understanding of the dynamic interplay between mobility and balance. limitations of this study include the small sample size, especially after outliers were removed. the small sample, though typical for pilot prosthetics research,53 limits generalizability. a larger sample would allow to further explore the relationship between gait speed and balance in prosthesis users while also considering additional factors such as prosthetic prescription, fitness level, and neurological conditions that may influence walking speed and balance. including upper and lower limb prosthesis https://doi.org/10.33137/cpoj.v8i1.45517 5 alhuzaymi a, fiedler g. exploring the correlation between gait speed and balance in limb prosthesis users: a pilot study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 8. doi:10.33137/cpoj.v8i1.45517 canadian prosthetics & orthotics journal issn: 2561-987x gait speed and balance in prosthesis users: a pilot study alhuzaymi a and fiedler g, 2025 users and one participant with multiple finger amputations, increased sample heterogeneity. the finger amputation may have proprioceptive balance effects, but results may differ substantially from participants with major limb loss. future, larger-scale, studies should analyze amputation types separately, as well as different types of prosthetic hardware. there is a possible training effect that influences nbwt scores and that could not be controlled in our protocol. conclusion in people who use limb prostheses, it cannot be assumed that there is a universal correlation between gait speed and balance. at least in some individuals, slow walking speed is not indicative of poor balance or vice versa. to ensure valid outcome assessments in clinical care, the two variables should be monitored separately. acknowledgements the authors thank daniel rusnak and bob maguire for their help in protocol design and subject recruitment. the authors also thank all participants for their time and valuable contributions to this study. declaration of conflicting interests the authors declare no conflicts of interest. authors’ contribution • dr. abdullah alhuzaymi: conceptualization, methodology, formal analysis, investigation, data curation, writing—original draft preparation, visualization, funding acquisition. • dr. goeran fiedler: conceptualization, resources, writing— review and editing, visualization, supervision, project administration, funding acquisition. both authors have read and agreed to the published version of the manuscript. sources of support internal support through the institution. this research received no external funding. references 1.owings m. ambulatory and inpatient procedures in the united states, 1996 [internet]. hyattsville (md): u.s. department of health and human services, centers for disease control and prevention; 1998 [cited 2025 may 29]. available from: https://pubmed.ncbi.nlm.nih.gov/9866429/ 2.wong ck, chihuri st. impact of vascular disease, amputation level, and the mismatch between balance ability and balance confidence in a cross-sectional study of the likelihood of falls among people with limb loss: perception versus reality. am j phys med rehabil. 2019; 98(2), 130–135. doi:10.1097/ 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myers am. the activities-specific balance confidence (abc) scale. j gerontol a biol sci med sci. 1995; 50a(1):m28-34. doi: 10.1093/gerona/50a.1.m28 32.berg ko, maki be, williams ji, holliday pj, wood-dauphinee sl. clinical and laboratory measures of postural balance in an elderly population. arch phys med rehabil. 1992; 73(11):1073-80. 33.sawers a, ting lh. beam walking can detect differences in walking balance proficiency across a range of sensorimotor abilities. gait posture. 2015; 41(2):619-23. doi: 10.1016/j.gaitpost.2015.01.007 34.major mj, fatone s, roth ej. validity and reliability of the berg balance scale for community-dwelling persons with lower-limb amputation. arch phys med rehabil. 2013; 94(11):2194-202. doi: 10.1016/j.apmr.2013.07.002. 35.miller wc, deathe ab, speechley m. psychometric properties of the activities-specific balance confidence scale among individuals with a lower-limb amputation. arch phys med rehabil. 2003; 84(5):656-61. doi: 10.1016/s0003-9993(02)04807-4 36.sawers a, hafner b. validation of the narrowing beam walking test in lower limb prosthesis users. arch phys med rehabil. 2018; 99(8):1491-1498.e1. doi: 10.1016/j.apmr.2018.03.012 37.sawers a, hafner bj. narrowing beam-walking is a clinically feasible approach for assessing balance ability in lower-limb prosthesis users. j rehabil med. 2018; 50(5):457-464. doi: 10.2340/16501977-2329 38.hafner bj, sawers ab. issues affecting the level of prosthetics research evidence: secondary analysis of a systematic review. prosthet orthot int. 2016; 40(1):31-43. doi: 10.1177/0309364614550264 39.cheng dky, dagenais m, alsbury-nealy k, legasto jm, scodras s, aravind g, et al. distance-limited walk tests post-stroke: a systematic review of measurement properties. neurorehabilitation. 2021; 48(4):413-439. doi: 10.3233/nre210026 40.watson mj. refining the ten-metre walking test for use with neurologically impaired people. physiotherapy. 2002; 88(7), 386– 397. doi:10.1016/s0031-9406(05)61264-3 41.carr jh, shepherd rb. walking. in: carr jh, shepherd rb, editors. stroke rehabilitation. oxford: butterworth-heinemann; 2003; 76-128. 42.bohannon rw. comfortable and maximum walking speed of adults aged 20–79 years: reference values and determinants. age ageing. 1997; 26,1,15–19, doi: 10.1093/ageing/26.1.15 43.crozara lf, laroche dp, marques nr, marques payão sl. assessing walking speed in persons with a lower-limb amputation: test-retest reliability of the 10-m walk test. prosthet orthot int. 2025; doi: 10.1097/pxr.0000000000000419 44.de winter jc, gosling sd, potter j. comparing the pearson and spearman correlation coefficients across distributions and sample sizes: a tutorial using simulations and empirical data. psychol methods. 2016; 21(3):273-90. doi: 10.1037/met0000079 45.cohen j. statistical power analysis for the behavioral sciences. 2nd ed. new york: routledge; 2013. 46.schumm wr, pratt kk, hartenstein jl, jenkins ba, johnson ga. determining statistical significance (alpha) and reporting statistical trends: controversies, issues, and facts. compr psychol. 2013; 1;2:03-cp. 47.fuenzalida squella sa, kannenberg a, brandão benetti â. enhancement of a prosthetic knee with a microprocessor-controlled https://doi.org/10.33137/cpoj.v8i1.45517 7 alhuzaymi a, fiedler g. exploring the correlation between gait speed and balance in limb prosthesis users: a pilot study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 8. doi:10.33137/cpoj.v8i1.45517 canadian prosthetics & orthotics journal issn: 2561-987x gait speed and balance in prosthesis users: a pilot study alhuzaymi a and fiedler g, 2025 gait phase switch reduces falls and improves balance confidence and gait speed in community ambulators with unilateral transfemoral amputation. prosthet orthot int. 2018; 42(2):228-235. doi:10.1177/0309364617716207 48. kahle jt, klenow td, sampson wj, highsmith mj. the effect of transfemoral interface design on gait speed and risk of falls. technol innov. 2016; 18(2-3):167-173. doi:10.21300/18.23.2016.167 49.lythgo n, marmaras b, connor h. physical function, gait, and dynamic balance of transfemoral amputees using two mechanical passive prosthetic knee devices. arch phys med rehabil. 2010; 91(10):1565-1570. doi:10.1016/j.apmr.2010.07.014 50.vaca m, stine r, hammond p, cavanaugh m, major mj, gard sa. the effect of prosthetic ankle dorsiflexion stiffness on standing balance and gait biomechanics in individuals with unilateral transtibial amputation. j prosthet orthot. 2022; 34(4): doi: 10.1097/jpo.0000000000000451 51.major mj, stine rl, gard sa. the effects of walking speed and prosthetic ankle adapters on upper extremity dynamics and stability-related parameters in bilateral transtibial amputee gait. gait posture. 2013; 38(4):858-863. doi:10.1016/j.gaitpost.2013.04.012 52.hafner bj, sanders je, czerniecki j, fergason j. energy storage and return prostheses: does patient perception correlate with biomechanical analysis?. clin biomech (bristol). 2002; 17(5):325-344. doi:10.1016/s0268-0033(02)00020-7 53.balkman gs, vamos ac, sanders je, larsen bg, hafner bj. prosthetists' perceptions of information obtained from a lower limb prosthesis monitoring system: a pilot study. j prosthet orthot. 2019; 31(2):112-120. doi: 10.1097/jpo.0000000000000203 https://doi.org/10.33137/cpoj.v8i1.45517 volume 6, issue 2 2023 articles in this special issue has been invited and reviewed by dr. silvia ursula raschke and dr. hossein gholizadeh. d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e v o l u t i o n i n p r o s t h e t i c s & o r t h o t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x https://jps.library.utoronto.ca/index.php/cpoj/editorinchief 1 hassan beygi b, wong m.s. contemporary and future development of 3d printing technology in the field of assistive technology, orthotics and prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.10. https://doi.org/10.33137/cpoj.v6i2.42225 stakeholder perspectives contemporary and future development of 3d printing technology in the field of assistive technology, orthotics and prosthetics hassan beygi b, wong m.s.* the department of biomedical engineering, the hong kong polytechnic university, hong kong. introduction three-dimensional (3d) printing is an additive manufacturing process to make 3d objects. with the evolution of this technique since the 1980s, its applications are becoming increasingly relevant to users of assistive technology, orthotics, and prosthetics services. to be more precise, we believe this digital transformation should be looked as a subset of more comprehensive technology, cad/cam (computer-aided design / computer-aided manufacturing). the cad software assists clinicians in capturing the shape of body segment(s) and designing purposeful devices for treatment purposes. it achieves this by reading a 3d captured shape of body segment from advanced 3d scanners and allowing for modifications to be made to the limb shape. the cam facilitates in the manufacturing process with reduction of manpower and increase of precision. 3d printing is only a part of this digital transformation, referring only to the additive manufacturing process, which is available in different types and forms, including powder, liquid, and solid materials.1 clinical and technological advancements are equally important in delivering quality assistive technology, orthotics, and prosthetics services. patients should be comprehensively assessed before an appropriate prescription of assistive technology, orthosis, or prosthesis is given. in the fabrication of assistive technology, orthosis, or prosthesis, advanced technological developments have the potential to offer the end-users an effective and reliable service. however, the enhancement of cad/cam (3d printing) technology should focus on facilitating the relevant clinical treatment outcomes. 3d printing serves as a revolutionary transformation in the design and fabrication of orthotic and prosthetic devices, reshaping the landscape with an excellent potential to improve the lives of people with disabilities. this technology could be deployed for use in hybrid manufacturing together with subtractive manufacturing or injection molding processes to produce a standalone 3d-printed appliance or sophisticated system. depending on the size and complexity of the design, it can either produce a whole shape through the printing process or print the parts which could be assembled to complete the system. the materials currently used to design and fabricate 3d printed orthotic and prosthetic devices include abs, nylon (pa 12 and pa 11), petg, pp, tpu, fiber reinforced composites, and silicone resins. there are several open access abstract 3d printing is considered as a helpful technology that facilitates innovative assistive technology, orthotics, and prosthetics development. this technology could likely contribute to positive treatment outcomes. it could also mitigate the challenges encountered when using the traditional methods. our team’s research in the application of 3d printing in prosthetics, orthotics and biomedical technology has shown beneficial results in its use. this article gives a general description on application of cad/cam, digitalization and 3d printing in this industry followed by short description of two spinal-related projects conducted in our research team. technological and clinical challenges on utilization of this technology have been listed. finally, this manuscript provides recommendation for broader applications and developments of the aforementioned technology through interdisciplinary practices. a glimpse into the future of 3d printing in the healthcare industry shows that this industry is poised to continue having a significant impact in this sector. it should be emphasized that assistive technology, orthotics, and prosthetics require a human touch and connection, and no digital tool or technology can replace such requirements. indeed, multi-disciplinary collaboration is the key to the success of applications of 3d printing. citation hassan beygi b, wong m.s. contemporary and future development of 3d printing technology in the field of assistive technology, orthotics and prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.10. https://doi.org/10.33137/cpoj.v6i2.42225 keywords 3d printing, orthotics, prosthetics, adolescent idiopathic scoliosis, rehabilitation, digitalization, cad/cam, technology, additive manufacturing * corresponding author: m.s. wong, phd the department of biomedical engineering, the hong kong polytechnic university, hong kong. e-mail: m.s.wong@polyu.edu.hk orcid id: https://orcid.org/0000-0002-4157-9528 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.10, 2023 special issue https://doi.org/10.33137/cpoj.v6i2.42225 https://doi.org/10.33137/cpoj.v6i2.42225 mailto:m.s.wong@polyu.edu.hk https://orcid.org/0000-0002-4157-9528 https://jps.library.utoronto.ca/index.php/cpoj/index 2 hassan beygi b, wong m.s. contemporary and future development of 3d printing technology in the field of assistive technology, orthotics and prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.10. https://doi.org/10.33137/cpoj.v6i2.42225 canadian prosthetics & orthotics journal issn: 2561-987x contemporary and future development of 3d printing technology hassan beygi b, and wong m.s., 2023 (special issue) advantages to using 3d printing, including, but not limited to:2-7 • material savings with less waste (plaster or foam blanks) therefore being more environmentally friendly. • elimination of storage of hard copy models, which saves space. • reduction of production time, labor-intensive manual work, and cost. for example, the lower-cost 3d printed prosthetics compared to expensive antiquated traditional prosthetics in which artisanal approaches are deployed. • solutions of customization and personalization as complicated designs could be easily implemented, a fact that can not be achieved with traditional manufacturing (thermoforming and lamination). for example, integrating unique patterns, personalized textures, variations in thickness across different areas, and incorporating built-in reinforcement profiles into the designs enhances the durability and breathability of the device. this approach likely promotes the use of prescribed orthotic or prosthetic devices among patients. • decrease of weight, as compared to traditional manufacturing, in which the plastic sheets or laminated layers were made as solid components, the implementation of hollow inside the layers by optimizing the infill to strike a balance between weight, strength, and printing time of the orthotic and prosthetic components. furthermore, a lattice structure could be implemented to decrease the weight and provide shock absorption properties, for example, in insoles. • extending the reach of 3d-printed orthotic and prosthetic devices to remote areas as well as less developed countries. • ease of addressing the continued growth of the children. the above-mentioned advantages could facilitate a wide range of devices and applications in the orthotics, prosthetics and assistive technology including: • inner and outer sockets for lower limb and upper limb loss, as well as cosmetic covers and hand prostheses • wheelchair accessories, including cup holders, custom wheelchair seats, adaptive utensils with enlarged grips, or customized shapes to help people with motor disabilities enhance feed. • customized afos, cranial remodeling helmets, insoles and footwear, hand splints, and spinal orthoses. • customized seating and positioning systems enhance the sitting posture of people with disabilities to decrease the chance of pressure sores. our team’s experiences in this area in considering the numerous advantages, our team has carried out research exploring the treatment effectiveness of the cad/cam method as compared to manual plaster casting method in managing adolescent idiopathic scoliosis. in the first study, the clinical parameters of cobb angle and apical vertebral rotation were evaluated at the pre-orthosis and the initial in-orthosis visits of 40 subjects. the mean decrease of cobb angle was almost 10% higher for the cad/cam method. the mean rectification time of the cad/cam method was shorter than that of the conventional manual plaster modification. our conclusion was that the cad/cam method can provide similar clinical results in the initial stage of the treatment compared to the manual method while saving time in rectification by 108.3 minutes (63.5%).8-9 in the second study, our team conducted a prospective randomized controlled trial to compare 1) clinical effectiveness and 2) quality of life between 3-d printed spinal orthoses and conventional orthoses. the conventional orthoses were made using vacuum forming technique to drape the heated plastic sheet on a positive trunk model. the study was limited to adolescent idiopathic scoliosis (ais). thirty females with ais who met the inclusion criteria (age 10-14, cobb angle 20-40°, risser sign “skeletal maturity” 0-2, and less than one year after the first menses) were recruited. patients were excluded if they suffered from musculoskeletal or developmental disease that prevented them to be complied with the treatment protocol. those recruited were randomly allocated to either 3d printing or conventional group. 3d printing technology was used to design and fabricate orthoses to manage ais, aiming to improve in-orthosis correction and patient compliance. 3d printed orthoses were made with 2.5 mm thick nylon 12 (pa-12) using the stratasys machine and fdm technique. the result showed that the patients wearing the 3d-printed orthoses experienced better clinical outcomes than those in the control group (conventional orthotic design) in terms of quality of life (qol) measured by questionnaire as well as similar immediate in-orthosis correction. cobb angle in 3d printing orthosis group decreased from 31.7°±6.0 in the baseline to 19.4°±3.9 in immediate in-orthosis condition. in the conventional orthosis fabrication group, the cobb angle of 29.8°±4.4 in the baseline showed a decrease to reach to in-orthosis cobb angle of 16.5°±6.8.10 it is proposed for future studies to consider reinforcement in strategic force application regions of the spinal orthosis using variant thickness in the different areas as well as exploring other materials and printing technologies that could be used for spinal bracing, e.g., polypropylene filament (pp) which has been deployed in some clinics recently. our experiences and findings in this study have led us to believe this technology has wider applications than traditional orthotic and prosthetic practice. for example, it can be deployed in assistive technology for animals who have lost limbs, fractures, or deformed limbs can access better medical care through 3d printing technology with https://doi.org/10.33137/cpoj.v6i2.42225 3 hassan beygi b, wong m.s. contemporary and future development of 3d printing technology in the field of assistive technology, orthotics and prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.10. https://doi.org/10.33137/cpoj.v6i2.42225 canadian prosthetics & orthotics journal issn: 2561-987x contemporary and future development of 3d printing technology hassan beygi b, and wong m.s., 2023 (special issue) customized artificial limbs, braces, pads, beaks, etc., which could increase their quality of life and longevity. another example of potential application of this technology is work we have done beyond the recently defined scopes of services for orthotists and prosthetists now deployed in hong kong for several years, is the provision of patientspecific surgical guides for intra-operative application and anatomical models to assist doctors in pre-operative planning through the application of 3d printing technology. irrespective of application, one of our findings across these various fields is that innovative technology application in the clinical setting could be only helpful and valuable when a team of experts with different backgrounds work together and supplement each other in both the development and application stages. the application of cad/cam (3d printing) technology could range from simple to complex assistive technology, orthosis, or prosthesis in which a wide range of clinical and technological knowledge, skills, and experiences is envisaged and needed. this can only be done with close collaboration among professionals from different disciplines. in working together interdisciplinarity, we have identified two general areas of importance that need to be considered by other researchers working on this 1) the technological challenges and 2) the clinical challenges. technological challenges there are several technological challenges, such as the selection of appropriate printing method, i.e., fdm (fused deposition modeling), sls (selective laser sintering), saf (selective absorption fusion), sla (stereolithography) or mjf (multi jet fusion) for the specific clinical purpose(s) as we also faced with some of them upon our clinical studies. considering the product allowance in terms of dimension, material, or bonding properties is essential. some vital physical and mechanical properties tests for suitability of clinical applications should be included, such as tensile, bending, and opening-closing tests, as well as body heat and humidity tests within the laboratory. the settings of 3d printing machines are versatile. for fdm, it includes the speed of 3d printing, the size and temperature of the nozzle, and the bed temperature, which may all affect the adhesion/bonding of the materials. on the other hand, the limited number of materials in sls technology, as well as powder quality, distribution, and density, play a vital role in the quality of 3d printed products. therefore, sometimes, the design needs to proceed using a trial-and-error process to obtain the desired orthotic or prosthetic component. another challenge is the limited selection of materials, as the material and the final orthotic or prosthetic device should pass a biocompatibility test to be considered medical-grade 3d printing materials. materials must meet iso standards regarding toxicity, skin irritation, and sensitization. the biggest challenge arises from assessing how materials react with the skin over the long term, as orthotic or prosthetic devices maintain direct contact with the skin. improvement of the surface finishing and durability of 3d printed prosthetics is another crucial element as fdm technology leaves distinct layer lines, and sls and mjf make a matte surface. post-process surface finishing is either physical smoothing, like sandblasting, or chemical smoothing, such as vapor smoothing through vaporized solvents. flexible printing materials are in demand in the o&p industry, and the most acceptable material up to this point of time tends to be tpu. however, it faces considerable difficulty because of its durability issue. as such, the vapor smoothing improves durability. to address bacteria proliferation, particularly on surfaces directly in contact with skin, such as liners, surface finishing could protect any liquid intake. nonetheless, this needs further improvement and accessibility to clinics and laboratories worldwide. finally, it is worth noting that in the application of additive manufacturing, several cad and 3d printing software requite a continued internet connection to identify license eligibility. while this requirement is understandable, alternative methods must be considered, as offline platforms are vital for those working in remote areas and providing orthotic and prosthetic services. application of generic mesh modification software in particular freeware versions could be kept into account. clinical challenges there are a number of clinical challenges, such as material allergies, the effect of body temperature and humidity on the materials used, and short-term and long-term clinical studies on acceptance and efficacy. as an analogy to the conventionally used thermoplastics, the 3d printed materials should be easily handled, including machining, grinding, and possibly modifying the 3d printed devices using the heat gun. one of the biggest challenges lies in the mindset of clinicians and technicians, who may be hesitant to partially transition from conventional methods to embracing digitalized 3d printing. overcoming this reluctance requires them to be open to learning and adapting themselves to become proficient digital practitioners. therefore, the reeducation of practitioners should be taken into consideration, as it would require the acquisition of new skills. nonetheless, it is essential to acknowledge that the expertise and creativity of clinicians and designers in utilizing digital tools within 3d design applications are critical. these skills can be transformed from traditional methods and effectively implemented in digital formats. it also reminds us the necessity to incorporate more https://doi.org/10.33137/cpoj.v6i2.42225 4 hassan beygi b, wong m.s. contemporary and future development of 3d printing technology in the field of assistive technology, orthotics and prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.10. https://doi.org/10.33137/cpoj.v6i2.42225 canadian prosthetics & orthotics journal issn: 2561-987x contemporary and future development of 3d printing technology hassan beygi b, and wong m.s., 2023 (special issue) components into the curriculum in different universities to synchronize with the rapid advancement in digital technologies. this will prepare students to be already comfortable and proficient with such technology once they start the clinical services. future outlook of 3d printing landscape the market is expected to become more populated with machine learning and ai (artificial intelligence) models and semi-automated designs through advancements in software, 3d scanning, and digitalized 3d printing workflow. while it is imperative for clinicians to get familiar with digital design, a semi-automated, repeatable workflow will help clinicians spend more time improving the designs, rather than grappling with digital tools to replicate traditional designs. more 3d printing machines will be anticipated into the orthotic and prosthetic market while 3d printing hardware, software, and materials will evolve concurrently. the development of new materials will provide further options in the selection of preferred materials for orthotic and prosthetic devices. the new materials could also address the need for durability, for example, in a remote, hot, and humid climate where the maintenance and frequent follow-up to the fitted devices may not be feasible. the application of pellet 3d printing could be considered as one of the solutions since there are a variety of thermoplastic materials in the form of pellets compared to the currently limited options for the filaments in the market. the application of metal 3d printing may get widespread, particularly for custom-made prosthetic and orthotic components for athletes or activity-specific devices. currently, these components are mainly manufactured using subtractive manufacturing, including cnc and laser cutting. however, once the metal 3d printing machines become more affordable, they could help clinicians design and manufacture the specific components tailor-made for the individual amputees. color printing is another domain that can be further practiced. it remarkably improves the adherence of children with disabilities/deformities to the prescribed orthotic/prosthetic appliances thanks to its enhanced aesthetic. like metal 3d printing, this is pending the development of more cost-effective machines in the near future. in summary, 3d printing would become a helpful technology that facilitates innovative assistive technology, orthotics, and prosthetics development. this technology could likely contribute to positive treatment outcomes. it could also mitigate the challenges encountered when using the traditional methods. however, it should be emphasized that assistive technology, orthotics, and prosthetics require a human touch and connection, and no digital tool or technology can replace such requirements. indeed, multidisciplinary collaboration is the key to the success of applications of 3d printing. call to action close collaboration among different disciplines is the essential prerequisite for the successful application of such technology into the clinical setting. moreover, a number of relevant clinical and technical research studies should be conducted before the cad/cam (3d printing) technology can be established and formulated as an evidence-based patient-centered practice in the field of assistive technology, orthotics, and prosthetics. the patient's safety should be listed as a priority in the implementation of this technology. acknowledgements the authors would like to acknowledge the content of www.3dheals.com and www.3dprintingindustry.com, where the webinars, interviews, and news related to the o&p practice were helpful in providing further input to parts of this manuscript. these platforms could be considered as two useful sources to support the updates in the application of 3d printing in this industry. declaration of conflicting interests authors declare that there is no financial or personal relationship with organizations or individuals that might have influenced our research. authors contribution both authors contributed equally to the research and the writing of this manuscript. sources of support none. references 1.tan ws, suwarno sr, an j, chua ck, fane ag, chong th. comparison of solid, liquid and powder forms of 3d printing techniques in membrane spacer fabrication. j membr sci. 2017;537:283-96. doi:10.1016/j.memsci.2017.05.037 2.the evolution of 3d printing in orthotics and prosthetics: a gamechanger in patient care [internet]. techmed 3d, 2023; [cited 2023 dec. 23]. available from: https://techmed3d.com/blog/evolution-3dprinting-orthotics-prosthetics-patient-care/ 3.3d printed prosthetic limbs allow patients to regain their mobility faster [internet]. alcam medical orthotics and prosthetics, 2022; [cited 2023 dec. 23]. available from: https://alcammedical.com/3dprinted-prosthetic-limbs/ 4.schwartz da, schofield ka. utilization of 3d printed orthoses for musculoskeletal conditions of the upper extremity: a systematic review. j hand ther. 2023;36(1):166-78. doi:10.1016/j.jht. 2021.10.005 5.van lieshout emm, verhofstad mhj, beens lm, van bekkum jjj, willemsen f, janzing hmj, et al. personalized 3d-printed forearm braces as an alternative for a traditional plaster cast or https://doi.org/10.33137/cpoj.v6i2.42225 http://www.3dheals.com/ http://www.3dprintingindustry.com/ https://techmed3d.com/blog/evolution-3d-printing-orthotics-prosthetics-patient-care/ https://techmed3d.com/blog/evolution-3d-printing-orthotics-prosthetics-patient-care/ https://alcammedical.com/3d-printed-prosthetic-limbs/ https://alcammedical.com/3d-printed-prosthetic-limbs/ 5 hassan beygi b, wong m.s. contemporary and future development of 3d printing technology in the field of assistive technology, orthotics and prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.10. https://doi.org/10.33137/cpoj.v6i2.42225 canadian prosthetics & orthotics journal issn: 2561-987x contemporary and future development of 3d printing technology hassan beygi b, and wong m.s., 2023 (special issue) splint; a systematic review. injury. 2022;53 suppl 3:s47-s52. doi: 10.1016/j.injury.2022.07.020 6.oud t, kerkum y, de groot p, gijsbers h, nollet f, brehm ma. production time and user satisfaction of 3-dimensional printed orthoses for chronic hand conditions compared with conventional orthoses: a prospective case series. j rehabil med clin commun. 2021;4:1000048. doi: 10.2340/20030711-1000048 7.ten kate j, smit g, breedveld p. 3d-printed upper limb prostheses: a review. disabil rehabil assist technol. 2017;12(3):300-14. doi: 10.1080/17483107.2016.1253117 8.wong ms, cheng jcy, lo kh. a comparison of treatment effectiveness between the cad/cam method and the manual method for managing adolescent idiopathic scoliosis. prosthet orthot int. 2005;29(1):105-11. doi: 10.1080/17461550500069547 9.wong ms, cheng jcy, wong mw, so sf. a work study of the cad/cam method and conventional manual method in the fabrication of spinal orthoses for patients with adolescent idiopathic scoliosis. prosthet orthot int. 2005;29(1):93-104. doi: 10.1080/ 17461550500066782 10.lin y, cheung jpy, chan ck, wong swf, cheung kmc, wong m, et al. a randomized controlled trial to evaluate the clinical effectiveness of 3d-printed orthosis in the management of adolescent idiopathic scoliosis. spine. 2021. doi: 10.1097/ brs.0000000000004202 authors scientific biography professor m.s. wong is a specialist in prosthetics and orthotics of the department of biomedical engineering, the hong kong polytechnic university. with his clinical and engineering training background, he has the educational vision of nurturing students with state-of-the-art professional knowledge and skills as well as all-rounded attributes, especially in positive attitude to tackle the uncertainties and challenges from this everchanging world, and in social responsibility to serve the lessprivileged people. his main research interests are scoliosis, spinal orthotics, prevention of fragility fractures, gait and posture analysis, cad/cam in prosthetics and orthotics, and prosthetics and orthotics outcome evaluations. dr. babak hassan beygi is a prosthetist & orthotist targeting on enhancement of the clinical outcomes of applied orthotic and prosthetic appliances with his research and clinical background. his main interests include the conservative treatment of spinal deformities as well as application of cad/cam technology in orthotics & prosthetics. https://doi.org/10.33137/cpoj.v6i2.42225 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 editorials raschke s.u. editor’s perspective on health economics in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.1. https://doi.org/10.33137/cpoj.v4i2.37135 english proofread by: karin ryan, m.a., b.sc., p.t. special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.37135 1 raschke s.u. editor’s perspective on health economics in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.1. https://doi.org/10.33137/cpoj.v4i2.37135 editorials editor’s perspective on health economics in prosthetics and orthotics raschke s.u.* british columbia institute of technology (bcit), 3700 willingdon avenue, burnaby, british columbia, canada. background in preparing this special edition, i took time to reflect on the importance of special editions in the publishing cycle of academic journals. special editions can collect the works emerging from a special event such as a conference or they can fill gaps in the literature where a topic has been underserved but is, nonetheless, worthy of attention. in this case it is the latter that motivated the editorial team. the idea for a special edition was sparked by a 60+ page long manuscript submitted for comment to the editors of the canadian prosthetics ad orthotics journal (cpoj) by dr. laurant frossard, from the queensland university of technology. the submission described a collaborative, interdisciplinary, payor-led project that used a novel, carefully considered methodology that was also applied and practical. the goal of the project was to develop an economic foundation and justification for osseointegration, which is the primary focus of dr. frossard’s team. while not suitable for peer-review publication due to its length, density and atypical format, the work this interdisciplinary collaboration did to establish this economic foundation is novel, interesting and directly related to the long-term financial sustainability of the prosthetics and orthotics sector. the thinness of literature on this topic sparked a discussion within the editorial team on the critical need to bring attention to this topic. it was then that we decided the time had come for our first special edition. over the past 20 years the entry level to practice in prosthetics and orthotics shifted to either a bachelor’s or master’s degree in most parts of the world, and a number of phd programs have been established. this shift provided the necessary educational basis to allow prosthetists and orthotists to participate in and lead research and has led to a growth of peer-reviewed knowledge published in academic journals which typically open access volume 4, issue 2, article no.1. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract there is a scarcity of literature exploring health economics in prosthetics and orthotics (p&o). the p&o sector has, over the past decades, moved to a bachelor’s or masters degree level as the requirement for entry to practice and, with that, there has been a growing body of research and knowledge generation focusing primarily on clinical aspects and engineering advances. no corresponding body of research has emerged on the economic aspects of p&o, creating a fundamental weakness in both technical and clinical research efforts to advance this field within an economically sustainable framework. this weakness will become critical as data driven engineering advances (e.g. exoskeletons, mass customizable prostheses) and clinical improvements (e.g. osseointegration, diabetes treatments) will make reimbursement for devices ever more complex and challenging. the tension between what is possible and what is fundable will increase unless what is possible also drives down costs. finding the right balance in prosthetics and orthotics will be a challenge, as this sector already struggles to justify current standards of care. this special edition takes a snapshot of stakeholder perspectives and opinions on the topic of health economics in p&o and is organized around the following stakeholder groups: end-user, researcher (engineering and clinical), prosthetic and orthotic practitioner and, of critical importance, four papers describing an interdisciplinary project on the health economics of osseointegration that was led by a payor. each author was also asked to provide a “call to action” in which they identify one or more key areas that need to be addressed in order to move forward with the barriers or opportunities they have identified in their paper. the intent of the special edition is to generate discussion and encourage more in-depth research on this topic. citation raschke s.u. editor’s perspective on health economics in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.1. https://doi.org/10.33137/cpoj.v4i2. 37135 keywords health economics, prosthetics, orthotics, rehabilitation engineering, business practices, health economic evaluation, evidence-based practices, reimbursement * corresponding author silvia ursula raschke, phd british columbia institute of technology (bcit), 3700 willingdon avenue, burnaby, british columbia, canada. e-mail: silvia_raschke@bcit.ca orcid id: https://orcid.org/0000-0001-7964-4295 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.37135 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.37135 https://doi.org/10.33137/cpoj.v4i2.37135 mailto:silvia_raschke@bcit.ca https://orcid.org/0000-0001-7964-4295 2 raschke s.u. editor’s perspective on health economics in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.1. https://doi.org/10.33137/cpoj.v4i2.37135 issn: 2561-987x health economics in prosthetics and orthotics raschke s.u, 2021 cpoj special s p e c ia l i s s u e focus on the evaluation of clinical practices, the development of evidence-based measures and the development of more sophisticated, better functioning componentry. however, a knowledge gap persists around objective economic and business-related issues. the provision pathway of prosthetic and orthotic care is not typically thought of in economic terms. nonetheless, the economics of this provision pathway are a strong undercurrent that drives events and decisions both at practical and at policy levels. this knowledge gap creates a fundamental weakness in both technical and clinical research efforts to advance this field. if it is not considered within the research and development process, the long-term economic sustainability of prosthetics and orthotics is jeopardized. credit must be given to researchers who have already begun to fill this knowledge gap, some of whom have contributed to this special edition, but more work needs to be done. the most comprehensive treatment of the topic is the recently published comprehensive systemic literature review of health economic evaluations in prosthetics and orthotics done by clark, dillon and shiell, who noted that, to the best of their knowledge, they are the first to have done such a review and that while some published papers exist, they are limited by relatively narrow focus. they point to a need for improving the evidence-based methodologies being used in prosthetics and orthotics to meet contemporary standards for rigorous health economic evaluation (hee) studies.1-3 need for a discussion on health economics in prosthetics and orthotics the identification of need for a deeper understanding of the underlying business and economic basis of the practice of prosthetics and orthotics comes at a critical time. the accelerating, data driven digital revolution is creating extraordinary opportunities for innovation in medical and rehabilitation technology development, as well as supporting clinical improvements in surgical techniques such as osseointegration, limb reattachment and more effective treatments for diabetes and neuromuscular disorders. alongside this, innovative software architecture and infrastructure to support new business models are being created, such that services and products can now travel from maker to the customer directly or can be created and delivered as a hybrid virtual model. this evolving ecosystem, driven by objective data, supports the creation of novel prosthetic and orthotic solutions that are likely to become increasingly personalized and diverse and that better meet the end-user’s needs. all of these will impact reimbursement models and, in the wake of this disruption of the status quo, payors will likely continue to focus on generating cost savings. the tension between what is possible and what is fundable will increase unless what is possible also drives down costs. finding the right balance in prosthetics and orthotics will be a challenge, as this sector already struggles to justify current standards of care. this brings us back to the health economics work done by dr. frossard and his collaborators, around which this issue is structured. the medical and engineering challenges that have been addressed by osseointegration researchers worldwide are significant and inspiring. this research challenges society to completely re-think amputation, rehabilitation and life with a prosthesis. but, in attempting to allow amputees to access the benefits brought by this new paradigm, a substantial barrier has to be overcome, namely making a convincing case to payors for the value the approach provides vs. the cost. in the same way, building a sustainable future in prosthetics and orthotics, both clinically and technologically, requires a realistic understanding of the economics and business constraints in the sector. both researchers and practitioners must incorporate economic realities and constraints into their work if they are to have any sort of prospect of that work making a meaningful impact. frossard et al were not the first to identify this barrier to novel approaches or technology in prosthetics and orthotics. however, they are the first to do a project which included representation from the payor side and to develop an objective methodology that considered carefully a wide range of inputs that can be used to calculate ‘value’ and not just ‘cost’ of the approach. the result is one of the most comprehensive treatments of the topic at this time. furthermore, this was a project that was led by the payor, which is a critically important differentiator, as payors have typically been silent when it comes to providing transparent, objective criteria which makes clear how they determine what they believe has value/what they will reimburse. response it was the recognition of the importance of generating a broad starting point for discussion on this topic that led to this edition on health economics in prosthetics and orthotics. because of the absence of an extensive, formal body of research and researchers to draw on, it was decided that the issue take the form of a collection of by-invitation stakeholder perspective pieces. as co-editor-in-chief i made the decision to give contributors considerable leeway with respect to format, length and focus because there are no standard formats for this kind of cross-over research in prosthetics and orthotics. this was done in order to make it easier for people to contribute to a body of work that is, in most cases, outside of their standard research repertoire or the daily work they do. what emerged is a collection of thoughtful and varied perspectives in an edition that is atypical in look, feel and balance. contributions varying widely in style, length and topic as they were written by a wide spectrum of stakeholders, all of whom provide a unique perspective on https://doi.org/10.33137/cpoj.v4i2.37135 3 raschke s.u. editor’s perspective on health economics in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.1. https://doi.org/10.33137/cpoj.v4i2.37135 issn: 2561-987x health economics in prosthetics and orthotics raschke s.u, 2021 cpoj special s p e c ia l i s s u e the topic in order to create an inclusive picture that respects the diversity of the people effected. the issue is organized around the following stakeholder groups: end-user, researcher (engineering and clinical), prosthetic and orthotic practitioner, educator and, in a category all on its own, dr. frossard’s team’s work, which was broken down into four papers, in order to present as much of their work as possible in easier to digest portions. i am particularly pleased to include the voices of two stakeholder groups that are very often not given much profile in academic literature in this edition – prosthetic & orthotic clinical practitioners and prosthetic & orthotic device users. their voices are often excluded despite being profoundly impacted by all decisions made, especially at the funding policy level. the ordering of the papers is deliberate. the issue begins with the highly personal story of an end user who became involved in exoskeleton design when she unexpectedly became disabled. the next section focuses on topics relating to the importance of data and business intelligence. next are the works for frossard and his collaborators. then come a collection of innovative thought and approaches in the sector, followed by a career retrospective from professor sir saeed zahedi, obe that also looks forward and a final paper which answers prof sir zahedi, and other authors’, call to prosthetic and orthotic educators to better prepare graduates for the complex, data driven future that is coming. interspersed throughout are perspectives from clinical practitioners who form the bridge between engineers and innovators and the end user. the goal of this special edition is not to create a snapshot of the current ‘state of the art’ on this topic, but instead to spark discussion where there is an acknowledged knowledge gap, in the hope that it will encourage more researchers to engage in formalized research and publications on this topic. a further atypical feature is that each paper includes a “call to action”. each author was asked to consider what they have written and to identify one or more specific calls to action coming from that which they believe would create tangible value and to identify who or what institution has the authority to initiate that action. sometimes those who see solutions or who ‘feel the pinch’ of a problem are not in a position to enable change. therefore, it is important, in underserved areas, to both identify potential pathways toward solutions and to highlight who has the ability and authority to make identified changes happen. conclusion i would like to thank all the contributors who took a risk when they responded positively to our invitation to contribute to this eclectic special edition. and, i would like to thank the readers of this collection of works who may be challenged by what they read because of the atypical format and content. in laying out the edition our aim was to challenge readers to think outside the boundaries of their specialty, be it in clinical or engineering, and to spark a discussion on the unique challenges and opportunities that the prosthetic and orthotic market presents. it is only in considering perspectives from the full spectrum of stakeholders that a comprehensive understanding of the prosthetics and orthotics, as a whole, can be formed. i sincerely hope that this special edition will inspire some readers to delve into this topic in a deeper way, to benefit all stakeholder represented in this edition. call to action i will end this introduction with my own call to action, which is that i ask that those persons or institutions identified as having the ability and authority to make change happen seriously deliberate on the calls and the underlying issues that led to their formulation and proceed to act on them. acknowledgements i would like to acknowledge my managing editor, dr. hossein gholizadeh for his support and advice. the name of a (co-)editorin-chief features visibly in academic journals, but without the hard work of the managing editor, we would never reach the publication stage. without dr. gholizadeh’s support and considerable effort, this special edition would not exist. declaration of conflicting interests i have no conflicts to interest to declare. sources of support none. references 1.clarke l, dillon m, shiell a. health economic evaluation in orthotics and prosthetics: a systematic review protocol. syst rev. 2019; 8(1):1-8. doi:10.1186/s13643-019-1066-9 2.clarke l, dillon mp, shiell a. a systematic review of health economic evaluations in orthotics and prosthetics: part 1– prosthetics. prosthet orthot int. 2020; doi: 10.1177/ 0309364620935310 3.clarke l, dillon mp, shiell a. a systematic review of health economic evaluation in orthotics and prosthetics: part 2—orthotics. prosthet orthot int. 2021;45(3):221-34. doi: 10.1097/ pxr. 0000000000000003 https://doi.org/10.33137/cpoj.v4i2.37135 4 raschke s.u. editor’s perspective on health economics in prosthetics and orthotics. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.1. https://doi.org/10.33137/cpoj.v4i2.37135 issn: 2561-987x health economics in prosthetics and orthotics raschke s.u, 2021 cpoj special s p e c ia l i s s u e author scientific biography dr silvia raschke, phd, is an applied researcher with the british columbia institute of technology make+ group. she specializes in evaluation and product development projects in rehabilitation engineering with a focus on prosthetics and orthotics. in 2013 she and collaborator, dr. michael orendurff, phd won the thranhardt prize for their paper: "can you tell which foot is which?", the first double blind prosthetic foot evaluation that included community ambulation. she is currently involved in a diverse range of projects, including orthotic aspects of exoskeleton design, curriculum development and acting as a mentor to a team of young researchers who are doing a project examining glass ceilings in prosthetics and orthotics. she is co-editor-in-chief of the canadian prosthetics and orthotics journal and chair of the us veterans affairs rehabilitation research and development (rr&d) subcommittee on rehabilitation engineering and prosthetics/orthotics. https://doi.org/10.33137/cpoj.v4i2.37135 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 2 2024 research article de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i2.44191 1 de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 research article overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands de laat f.a1*, kühne s.w.m2, de vos w.c.a.j.2, geertzen j.h.b.3 1 rehabilitation centre leijpark, libra rehabilitation medicine & audiology, tilburg, the netherlands. 2 livit ottobock care, ‘s hertogenbosch and dordrecht, the netherlands. 3 university of groningen, university medical centre groningen, department of rehabilitation medicine, groningen, the netherlands. introduction cycling is an activity with a number of benefits. it can be done as a recreational activity and is a cheap and ecofriendly way of transportation, especially in flat countries like the netherlands.1 for rehabilitation purposes, cycling is a good way to train the cardiovascular system and strengthening the leg muscles.2 persons with a lower limb amputation (lla) can also benefit from cycling. cycling is joint friendly, as the majority of body weight is supported by the bicycle seat, thereby reducing the load on the residual limb,3 but cycling requires more degrees of flexion at the hip, knee and ankle than walking.4 especially in persons with a lla due to diabetes, limited joint mobility is common, affecting the range of motion of hip and knee.5 to address these limitations in range of motion, adaptations can be made to either the prosthesis or the bicycle.6 open access abstract background: cycling has a number of benefits, especially for individuals with a knee disarticulation or transfemoral prosthesis. however, the barriers they face in cycling are not well understood. objectives: to explore the barriers in cycling experienced by users with a knee disarticulation or transfemoral prosthesis, and to gather solutions to overcome these barriers. methodology: a qualitative research approach was used. in-depth, semi-structured, self-developed interviews were conducted with experienced prosthetic users (n=8) and an adapted version was used for certified prosthetists/orthotists (cpos) (n=3). the interview included physical, psychological, prosthetic, and bicycle-related items. findings: based on the findings from the interviews, the following barriers and corresponding recommendations were identified: • physical barriers: exertion, skin damage in the groin area and discomfort in the back and hip. o recommendation: use of an electric bicycle and use of a crank shortener or saddle adjustment to overcome asymmetry in cycling. • psychological barriers: fear of falling or fear of balance disturbances. o recommendation: taskand context-specific training, or graded exposure to cycling during prosthetic training, along with potentially using a more advanced bike with improved balance. • prosthetic barriers: problems with switching the knee prosthesis mode for cycling; challenges with prosthetic suspension; and discomfort caused by the socket brim design. o recommendation: manufacturers should integrate automatic detection of cycling in microprocessor prosthetic knee joints; use of a total elastic suspension belt (tes-belt); and lowering the ventral edge of the socket. • bicycle-related barriers: slipping of the prosthetic foot off the pedal. o recommendation: use of anti-slip pedals or a block heel under the shoe. conclusion: by addressing the challenges and barriers, we aim to promote greater engagement in cycling, which offers significant physical and psychological benefits for persons with knee disarticulation or transfemoral amputation. eventually, this can enhance their quality of life and foster greater independence. article info received: october 23, 2024 accepted: december 9, 2024 published: december 12, 2024 citation de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i 2.44191 keywords amputation, cycling, prosthesis, mobility, knee disarticulation, transfemoral amputation, bicycle, netherlands, interview, rehabilitation, prosthetic foot * corresponding author: fred a. de laat, md, phd, affiliation: libra rehabilitation medicine & audiology, tilburg/eindhoven, the netherlands. e-mail: f.delaat@libranet.nl orcid id: https://orcid.org/0000-0002-4348-5998 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 2, article no.4. 2024 https://doi.org/10.33137/cpoj.v7i2.44191 https://doi.org/10.33137/cpoj.v7i2.44191 https://doi.org/10.33137/cpoj.v7i2.44191 mailto:f.delaat@libranet.nl https://orcid.org/0000-0003-3947-293x https://jps.library.utoronto.ca/index.php/cpoj/index 2 de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 canadian prosthetics & orthotics journal issn: 2561-987x overcoming cycling barriers for prosthesis users de laat et al., 2024 there are several studies assessing the influence of facilitators and barriers in cycling with a knee disarticulation or transfemoral prosthesis.7-9 in an older study in slovenia, persons with a transtibial amputation cycled more than persons with a transfemoral amputation.7 in a thai study, persons with a transtibial amputation were 4.5 times more likely to cycle than persons with a knee disarticulation or transfemoral amputation.8 the components of the knee disarticulation and transfemoral prosthesis did not influence the chance in cycling after an lla, although limited knee flexion ability was mentioned as a barrier. participants also reported the prosthetic foot slipping off the pedal as a barrier. in that study, almost all participants used their daily prosthesis and shoes while cycling and reported that the prosthetic foot slipping off the pedal was a barrier.8 the circumstances in thailand, however, differ considerably from those in western countries like the netherlands, particularly in terms of income and traffic. in a recent study in the netherlands9 an overview was given of facilitators and barriers related to cycling participation in people with an lla. a dynamic foot positively predicted cycling, whereas adjuvant comorbidity negatively predicted cycling. however, in that study, specific physical and emotional barriers were not mentioned, nor specific factors related to prosthesis or bicycle.9 the objective of this pilot study was to explore barriers to cycling and identify solutions by interviewing experienced users of knee disarticulation or transfemoral prostheses, as well as prosthetists working with lower limb amputee cyclists. methodology participants participants were recruited from two orthopedic services in the region of dordrecht and eindhoven, the netherlands. all participants gave informed consent. a waiver from the local medical ethical committee was obtained for this study (metc brabant nr nw2020-41). inclusion criteria required participants to be regular cyclists with a knee disarticulation or transfemoral amputation. one of the authors (sk) contacted eligible participants, all of whom agreed to participate in the study. in addition to user opinions, it is important to include the perspectives of certified prosthetists/orthotists (cpos). therefore, cpos with substantial experience (>7 years and working with 10–40 patients who cycle with knee disarticulation or above-the-knee prostheses) were also recruited. procedure participants with a knee disarticulation or a transfemoral amputation were asked to participate in an in-depth semistructured interview with one of the assessors (sk). this interview was self-developed, as no validated interview scheme or questionnaire was available on assessing cycling with a lower limb prosthesis. the interview (in dutch) comprised open questions about experiences in cycling, barriers in the interaction between prosthesis and bicycle, and recommendations for diminishing these barriers. characteristics of the participants (age, gender, amputation level, amputation side, type of prosthetic knee and foot, kind of bicycle (motorized or not)) were recorded. the interview framework is provided in appendix a. for the cpo’s, an adapted interview instrument (appendix b) was developed to assess risks associated with cycling using a prosthesis, and barriers related to the interaction between the prosthesis and the bicycle, and possible recommendations and their consequences. the characteristics of the cpos (years of experience, number of treated persons with an lla who cycle) were recorded. data analysis all answers to the interview questions were recorded verbatim, resulting in detailed descriptions of the barriers and recommendations. to ensure the original meaning was preserved, the participants’ quotes were translated faithfully in english afterwards by an independent native englishspeaking cpo, working in the netherlands. these barriers and recommendations were clustered by two independent assessors (fdl and wdv) in 4 categories, based on the global components of the framework of the international classification of functioning, disability and health (icf):10 1: physical barriers affecting individuals with an lla, especially skin damage and pain in the back and hips (body functions and structures in the icf model) 2: psychological barriers affecting individuals with an lla, especially fear of balance disturbances (personal factors in the icf model) 3: prosthetic barriers affecting individuals with an lla, especially the cycle mode in microprocessor knees (mpk’s) (environmental factors, [body-related] in the icf model) 4: bicycle barriers affecting individuals with an lla, especially the interaction between prosthetic foot and the pedal (environmental factors, [not body-related] in the icf model). differences in clustering between assessors were discussed until consensus was reached. results characteristics of the participants we approached eight individuals with an lla (6 with a transfemoral amputation, 2 with a knee disarticulation, numbers 1-8), fulfilling the inclusion criteria, and all agreed https://doi.org/10.33137/cpoj.v7i2.44191 3 de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 canadian prosthetics & orthotics journal issn: 2561-987x overcoming cycling barriers for prosthesis users de laat et al., 2024 to participate. the characteristics of these participants are presented in table 1. we also recruited three cpos (numbers 9-11). they had on average 15 years of experience, and the average number of treated persons with an lla who cycle was 10-40 per year per cpo. barriers and recommendations in cycling all barriers, reported more than once, are clustered and presented in table 2. 1 ) physical barriers skin damage and exertion were the most frequently reported barriers among all the barriers mentioned (82%). answers of two participants and two cpos were representative of the physical barriers mentioned: 1: “pedaling with just one leg is tiring.” 5: “especially the skin that rubs open. in particular in the groin and the top in my hip, where the edges of the prosthesis are located, that presses most on the skin.” 8: “i had chafing spots with the previous socket, mostly on the hip, because you have more friction there. that socket was quite high and when you make the cycling movement, you continuously get a kind of rubbing effect. the socket connects higher than when walking and, because the cycling motion is greater, it irritated me.” 9 (cpo): “you can get adhesions in the groin region. these adhesions are between the skin and the socket. while cycling, your movements become viscous, causing a lot of friction, and then the skin eventually breaks... usually the socket chafes against the skin. in fact, the problems are always in the groin region. or that they are really starting to get pressure ventrally proximal because the socket is pressing there when cycling.” 10 (cpo): “pressure spots ... depends a bit on the position. the socket can start to push in the front and into the groin.” a recommendation to overcome exertion was to use an electric bicycle. the interaction between the skin and the socket brim during cycling, caused by the constant movement of the thigh, generates shear forces in the groin area. a recommendation was the use of a crank arm shortener, which was unknown for several participants with an lla. another recommendation to prevent skin problems is to adjust the saddle or remove the outer part of the saddle on the prosthetic side. in addition, it is recommended to lower the socket and use it in combination with a liner. a socket with soft material on the proximal side (soft-brim socket) is also recommended to reduce problems, if the residual limb is long enough. participants reported that back pain was primarily caused by asymmetry during cycling. this asymmetry during cycling has two main causes: first, force application to the pedal is significantly limited with the prosthetic limb, resulting in the majority of the force being generated by the sound limb, which leads to an asymmetrical movement and posture on the saddle. second, the shape of the socket brim can exert pressure on the groin due to the increased hip flexion required during cycling, which also can lead to an asymmetrical posture on the saddle or cause the upper body to compensate (by leaning backward) in order to avoid discomfort. for this item, the use of a crank arm shortener was proposed again. table 1: participant demographics and prosthetic characteristics. abbreviations: tf, transfemoral; kd, knee disarticulation; mpk, microprocessor knee; irc socket, transfemoral socket standard with ischial ramus containment (irc) design. gender (f/m) age (y) amputation side (r/l) amputation level type of prosthetic knee mechanic (m)/mpk type of prosthetic foot type of prosthetic socket liner cycling level per week (km) e-bike (yes/no) 1 f 56 r tf c-leg mpk triton irc socket no 0,5-30 no 2 m 52 l kd genium mpk triton hd knee disarticulation socket yes 0,5-1 no 3 f 71 r tf 3r106 pro m trias soft brim socket yes 0,5-3 yes 4 m 35 r tf rheo knee mpk variflex rotate irc socket no 0,5-30 yes 5 m 78 l tf vgk m triton irc socket yes 15 no 6 f 46 l kd genium mpk triton knee disarticulation socket (volume adjustable) yes 20 no 7 m 66 l tf rheo knee mpk talux irc socket yes 25-50 yes 8 f 25 l tf genium mpk trias soft brim socket no 0,5-10 no https://doi.org/10.33137/cpoj.v7i2.44191 4 de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 canadian prosthetics & orthotics journal issn: 2561-987x overcoming cycling barriers for prosthesis users de laat et al., 2024 table 2: clustered barriers reported by the person with an lla and their cpo. abbreviation: cpo, certified prosthetists/orthotists; lla, lower-limb amputation. barriers item person with an lla (n=8) cpo (n=3) total (n=11) n n n physical items skin damage 6 3 9 back pain 4 1 5 exertion 6 0 6 psychological items fear of falling 4 2 6 fear of balance disturbances 3 1 4 prosthetic items knee prosthesis cycling mode 6 2 8 fitting of the socket/suspensi on/socket trim line 5 2 7 bicycle items prosthetic foot slipping off the pedal 6 3 9 2) psychological barriers fear of falling and concerns about balance disturbances were mentioned as psychological barriers. fear was experienced when stepping on and off the bike, as well as when navigating busy roads. answers of two participants were representative of the psychological barriers mentioned: 5: “i have trouble balancing, i am getting older and more anxious… i am afraid i will fall on the prosthetic side.” 9 (cpo): “often prosthetic users are afraid of cycling.” 3) prosthetic barriers the majority of the participants with an lla (using a mpk) were dissatisfied with the knee's cycling mode. this is because of the necessity of using a cell phone to activate/deactivate the cycling mode. some participants with an lla forgot to switch off the cycling mode after use, which led to dangerous situations. 1: “it is too cumbersome, it takes too much time. first you have to take your phone, unlock and open the application and connect to the prosthesis, which also takes a while. i think it takes 30 seconds to a minute to activate the bike mode. i do not think it is customer friendly.” 1: “apart from that when you get off, you have to take it off bike mode again, otherwise there is a risk of falling.” 6: “i often forgot to change the knee-setting after cycling.” 8: “so you have to start it, wait a while ... then it can connect. i often have my bluetooth switched off, because otherwise my battery will drain quickly, so it is frustrating that bluetooth is still on.” 10 (cpo): “attention must be paid to the knee-settings, which have to be changed when getting on and off.” all participants suggested implementing an automatic detection feature for the cycling mode of the mpk, if not already present. if this is not possible, a second best solution is a switch on the prosthesis (like the very good knee (vgk) knee) instead of using a cell phone. the fitting of the socket was frequently mentioned as a barrier, due to too much sweating and loosening of the vacuum during cycling. 8: “when you cycle, there is no vacuum anymore, because air is not anymore pumped out of the socket. if you sweat while doing this, there is also the chance that your socket will slide off your stump. because you are cycling you do not have the effect that the air is blown or pushed out of the socket.” 10 (cpo): “the constant rotating movement pushes the socket against the saddle. the socket comes loose from the saddle... which leads to failure of the prosthesis. constant friction and perspiration can also cause the socket to detach from the stump more quickly.” to overcome fitting problems of the socket, a total elastic suspension (tes) belt was recommended (figure 1). figure 1: tes-belt. picture, made by one of the co-authors, with permission. 4) bicycle barriers the interaction between prosthetic foot/shoe and the pedal, especially the prosthetic foot slipping off the pedal was most frequently reported. 2: “i really have to pay attention. checking whether the foot is properly on the pedal while cycling. check every time, keep an eye on the foot each time to see if it needs to be repositioned.” https://doi.org/10.33137/cpoj.v7i2.44191 5 de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 canadian prosthetics & orthotics journal issn: 2561-987x overcoming cycling barriers for prosthesis users de laat et al., 2024 5: “i adjust the position of my foot and make use of the height of the heel. i then press my heel on the pedal.” 6: “to prevent the prosthesis from slipping away i had a strap but that is not easy to use. i couldn't get my foot out of it and could not get off my bike in traffic. also, i had to put the pedal in a straight position before i put my foot in it and then my foot slid in so deep, i could not get it out again. that does not work and is very dangerous.” 7: “i make sure i put my foot on the pedal correctly, heel behind the pedal, so on good roads nothing dangerous happens.” 8: “we also bought a click system. but because one had to put shoes on again to cycle, we bought expensive shoes which we never used because i found it too impractical.” 10 (cpo): “yes, depending on what type of knee you have. the moment you have a knee that wants to push the knee to extend it slowly moves forward, if it is not locked. then you have to secure it to the pedal.” to overcome the problem of the prosthetic foot slipping off the pedal, participants with an lla tried a lot of solutions to click the shoe on the pedal, but frequently unlocking the shoe was dangerous. two participants recommended a block heel (figure 2) to prevent the prosthetic foot slipping off the pedal and were satisfied with it. figure 2: block heel under the shoe. picture of one of the coauthors. discussion in this study, we assessed barriers to cycling for individuals with a knee disarticulation or transfemoral amputation. we gathered and clustered barriers and recommendations in order to expand the possibilities for cycling. the most commonly mentioned barriers were exertion, residual limb skin damage and the prosthetic foot slipping off the pedal. additionally, the method of switching the cycling mode on and off in the mpk using a cell phone was mentioned as a problem. fear of falling, or fear of balance disturbances were the most mentioned psychological items. in a former thai study,8 the most commonly mentioned barriers were pain and discomfort during cycling. however, in that study, most participants had a transtibial amputation, and none of the participants with a knee disarticulation or transfemoral amputation used an mpk. to overcome physical problems like skin damage or back pain, a crank arm shortener is proposed. another option is lowering the edge of the socket, but most of the cyclists use the same prosthesis for cycling as for walking.8 therefore, this solution can disturb the way of walking with the prosthesis and is only possible if the residual limb is long enough. to overcome exertion, an electric bicycle was recommended. in terms of psychological barriers, fear can be diminished by enlarging self-confidence. the literature suggests that taskand context-specific training, along with graded exposure to cycling, should be initiated as soon as possible to address this issue effectively.11 for adults with poor performance and a fear of falling or balance disturbances, the literature suggests that bike adaptations can help, such as a lower frame and automatic saddle height adjustment. these modifications can make it easier to step on and off the bike and ensure that the feet are flat on the ground when standing.12 the prosthetic barriers mentioned by the participants were activating and deactivating the cycling mode of the knee and the fitting of the socket. the first item should be addressed by the manufacturers of the microprocessor prosthetic knees by integrating automatic cycling detection. participants rejected solutions that rely on cell phone operation for mode switching. the fitting of the socket can be improved by using a tes-belt (figure 1). the literature describes an open socket technique for individuals with knee disarticulation, which could be a solution.13 the bicycle-related issue that was most frequently mentioned was the prosthetic foot slipping off the pedal. most of the participants had made adaptations of the pedal, such as larger pedals with anti-slip, or a rubber strip on the lateral side of the pedal, to prevent the shoe from slipping off to the lateral side. these adaptations were satisfactory for the cyclists who made them. two participants recommended a shoe with a block heel to prevent the prosthetic foot slipping off the pedal (figure 2). other tried adaptations, such as a toe clip or shoe cleat were not recommended, due to dangerous situations when unlocking. in summary, individuals with knee disarticulation or transfemoral amputation have the potential to regain their ability to cycle. prerequisites include a rehabilitation team with the necessary resources, such as an adapted bicycle https://doi.org/10.33137/cpoj.v7i2.44191 6 de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 canadian prosthetics & orthotics journal issn: 2561-987x overcoming cycling barriers for prosthesis users de laat et al., 2024 and/or saddle, expertise in cycle training, and a cpo with experience and interest in cycling, capable of creating an appropriate socket and suspension system. study strengths and limitations a strength of the study is the broad experience and expertise of the participants, so a lot of barriers and recommendations could be gathered. we included individuals with an lla ensuring diversity in age, gender, cycling distance levels, and types of prosthetic knees used. it could be seen as a limitation that all participants were recruited in two orthopedic services, so a selection bias could not be excluded. a further limitation of our study was the use of a self-developed interview scheme that was not validated. however, no validated tool existed, nor was there any information from scientific studies to base development of such a tool. this may have had an influence on the outcomes, although the questions asked were as broad as possible, to provide the participants with adequate room for their interpretation. at last it is questionable if saturation occurred in this pilot study. in general, saturation can be achieved in a narrow range (up to 9–17) of interviews, particularly in studies with relatively homogenous study populations and narrowly defined objectives.14 during our study, the penultimate participant (a cpo) gave a recommendation to prevent skin damage, whereas the last participant had no new barriers in cycling. therefore, we think that lack of saturation has at most a minor influence in our results. conclusion there are several barriers in cycling experienced by users with knee disarticulation or transfemoral prosthesis. addressing these challenges and barriers aims to increase engagement in cycling, thereby providing substantial physical and psychological benefits for this population. eventually, this can enhance their quality of life and foster greater independence. future research could focus on multicenter, larger-scale studies with interventions for better cycling, such as an improved socket, or adjustment of the saddle or crank. acknowledgements we wish to thank all patients and cpos that participated in the study. declaration of conflicting interests • fred de laat: nothing to be declared. • sabine kuhne: employee of livit ottobock care. • wouter de vos: employee of livit ottobock care. • jan geertzen: nothing to be declared. authors’ contribution • fred de laat: research design, analysis and interpretation of the data, first draft of the manuscript, manuscript preparation. • sabine kuhne: research design, data-acquisition, analysis and interpretation of the data, manuscript preparation. • wouter de vos: research design, analysis and interpretation of the data, manuscript preparation. • jan geertzen: analysis and interpretation of the data, manuscript preparation. all authors have read and approved the final version of the manuscript. sources of support none. references 1.poonsiri j, dekker r, dijkstra pu, hijmans jm, geertzen jhb. bicycling participation in people with a lower limb amputation: a scoping review. bmc musculoskelet disord. 2018;19(1):398. doi: 10.1186/s12891-018-2313-2 2.oja p, titze s, bauman a, de geus b, krenn p, reger-nash b, et al. health benefits of cycling: a systematic review. scand j med sci sports. 2011;21(4):496-509. doi: 10.1111/j.1600-0838.2011.01299 .x 3.ericson mo, bratt a, nisell r, németh g, ekholm j. load moments about the hip and knee joints during ergometer cycling. scand j rehabil med. 1986;18(4):165-72. 4.ericson mo, nisell r, nemeth g. joint motions of the lower limb during ergometer cycling. j orthop sports phys ther. 1988;9(8):273-8. doi: 10.2519/jospt.1988.9.8.273 5.francia p, anichini r, seghieri g, de bellis a, gulisano m. history, prevalence and assessment of limited joint mobility, from stiff hand syndrome to diabetic foot ulcer prevention: a narrative review of the literature. curr diabetes rev. 2017; 14(5):411-26. 6.childers wl, kistenberg rs, gregor rj. the biomechanics of cycling with a transtibial amputation: recommendations for prosthetic design and direction for future research. prosthet orthot int. 2009;33(3):256-71. doi: 10.1080/03093640903067234 7.burger h, marinček č, isakov e. mobility of persons after traumatic lower limb amputation. disabil rehabil. 1997;19(7):2727. doi: 10.3109/09638289709166538 8.poonsiri j, dekker r, dijkstra pu, nutchamlong y, dismanopnarong c, puttipaisan c, et al. cycling of people with a lower limb amputation in thailand. plos one. 2019;14(8):e0220649. doi: 10.1371/journal.pone.0220649 9.poonsiri j, dekker r, dijkstra pu, hijmans jm, geertzen jhb. cycling in people with a lower limb amputation. bmc sports sci med rehabil. 2021;13(1):75. doi: 10.1186/s13102-021-00302-3 10.international classification of functioning, disability and health (icf) [internet]. who, geneva. 2001; [cited 2024, october 23]. available from: https://www.who.int/standards/classifications/internationalclassification-of-functioning-disability-and-health https://doi.org/10.33137/cpoj.v7i2.44191 https://www.who.int/standards/classifications/international-classification-of-functioning-disability-and-health https://www.who.int/standards/classifications/international-classification-of-functioning-disability-and-health 7 de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 canadian prosthetics & orthotics journal issn: 2561-987x overcoming cycling barriers for prosthesis users de laat et al., 2024 11.van twillert s, postema k, geertzen jhb, hemminga t, lettinga at. improving rehabilitation treatment in a local setting: a case study of prosthetic rehabilitation. clin rehabil. 2009;23:938-47. doi: doi: 10.1177/0269215509338125 12.dubbeldam r, baten c, buurke jh, rietman js. sofie, a bicycle that supports older cyclists? accid anal prev. 2017; 105:117-23. doi: 10.1016/j.aap.2016.09.006 13.otter n, postema k, rijken raj, van limbeek j. an open socket technique for through-knee amputations in relation to skin problems of the stump: an explorative study. clin rehabil. 1999;13:34-43. doi: 10.1177/026921559901300105 14.hennink m, kaiser bn. sample sizes for saturation in qualitative research: a systematic review of empirical tests. soc sci med. 2022;292:114523. doi: 10.1016/j.socscimed.2021.114523 https://doi.org/10.33137/cpoj.v7i2.44191 8 de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 canadian prosthetics & orthotics journal issn: 2561-987x overcoming cycling barriers for prosthesis users de laat et al., 2024 appendix a: interview framework for cycling with a knee-disarticulation or transfemoral prosthesis. demographics sex: age: amputation level: amputation side: type of prosthetic knee: type of prosthetic foot: type of prosthetic socket: type of liner: weekly cycling distance (in kilometers) type of bike (e-bike or regular bike) reasons for cycling initial question follow up questions could you tell us the reasons you cycle? how often do you cycle? with whom do you cycle? how do you feel after cycling? what kind of feeling do you have after cycling? benefits of cycling initial question follow up questions in what ways does cycling benefit you? impact on physical health? impact on mental health? impact on social life? impact on independence? new life possibilities from cycling? barriers to cycling initial question follow up questions how was your experience cycling for the first time? why did you want to cycle? what type of bicycle did you use? how did it feel to get on and off the bicycle? how did you manage switching the mode of the mpk knee between cycling and walking? was the saddle height comfortable? did you feel symmetry in movement between your left and right sides? how would you describe your cycling experience? long distance short distance with stopovers what barriers do you experience while cycling? socket discomfort stump issues, sweating prosthetic knee limitations prosthetic foot limitations movement restrictions (e.g., difficulty bending or extending the hip) muscle strength pain maximum cycling distance getting on and off the bike have you ever experienced a dangerous situation in traffic? have you ever fallen off the bike? modifications to the bike initial question follow up questions do you have any modifications to your bike? typical characteristics of the bike: • backpedal brake • gears • frame height • saddle • click system adaptations to the bike: • prosthetic or shoe adaptations what do you do to make cycling easier? what do you think of a solution to make cycling easier? https://doi.org/10.33137/cpoj.v7i2.44191 9 de laat f.a, kühne s.w.m, de vos w.c.a.j, geertzen j.h.b. overcoming barriers to cycling for knee disarticulation and transfemoral prosthesis users: a pilot study in the netherlands. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.4. https://doi.org/10.33137/cpoj.v7i2.44191 canadian prosthetics & orthotics journal issn: 2561-987x overcoming cycling barriers for prosthesis users de laat et al., 2024 demographics years of work experience: number of patients you have treated who cycle: what bike-related barriers do individuals with lower-limb prostheses face when cycling? stepping on or off the bike balance and stability type or model of the bike other challenges or barriers? what prosthesis-related barriers do individuals with lower-limb prostheses face when cycling? fit of the prosthesis prosthesis length socket model foot stiffness other challenges or barriers? what solutions have you implemented to address these issues? adaptation: problem: adaptation: problem: adaptation: problem: what risks or dangers are associated with cycling using a lower-limb prosthesis?" traffic-related risks risks involving other people risks related to the bike appendix b: cpos' insights on cycling with knee-disarticulation or transfemoral prostheses. https://doi.org/10.33137/cpoj.v7i2.44191 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 2 2025 letter to the editor bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. response to the letter to the editor regarding “health economic evaluation of microprocessor and non-microprocessor-controlled prosthetic knees”. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 7. https://doi.org/10.33137/cpoj.v8i2.46486 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i2.46486 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. response to the letter to the editor regarding “health economic evaluation of microprocessor and non-microprocessor-controlled prosthetic knees”. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 7. https://doi.org/10.33137/cpoj.v8i2.46486 letter to the editor response to the letter to the editor regarding “health economic evaluation of microprocessor and non-microprocessor-controlled prosthetic knees” bosman c.e1*, van der sluis c.k1, vrieling a.h1, geertzen j.h.b1, seves b.l1, groen h2 1. department of rehabilitation medicine, university of groningen, university medical center groningen, groningen, the netherlands. 2. department of epidemiology, university of groningen, university medical center groningen, groningen, the netherlands. dear editor, we thank colleagues brüggenjürgen, riemer and gapp for their detailed consideration and for recognizing the quality of our study.1 we appreciate that when comparing two lower-limb prosthetic devices across a range of prices, such as microprocessor-controlled and non-microprocessor-controlled prosthetic knees, the average reader would not expect an incremental cost-effectiveness ratio that exceeds values observed for expensive drugs such as monoclonal antibodies. however, it should be noted that the ratio not only reflects the difference in costs, but also the difference in effects. as the difference in effects becomes very small, the ratio will increase very sharply. in our case, the small qaly difference explains the high cost-effectiveness ratio, even though the cost difference is not excessive. with respect to the costs of prosthesis, we would like to clarify the design of our study to avoid misunderstanding. it is true that we included participants who had their first prosthesis fitted, as well as those who received a replacement. however, we treated both groups as if they were new fittings, in our comparison of prosthesis types. this was a deliberate choice to ensure a consistent cross-sectional comparison of prosthesis types. consequently, we assigned full costs of their respective prosthesis to all participants. we acknowledge that this approach influences icur estimates and agree that assumptions about replacement cycles warrant further investigation. we regret that the impression was given that a very short replacement cycle would be required. in fact, in the first paragraph of our discussion, we refer to a previous study that suggests that cost-effectiveness of the mpk may improve in the long term due to lower healthcare costs related to falls. thus, the higher initial costs of mpk could be at least partially compensated. we appreciate your recalculations of icur,2 but we feel that the proposed corrections to our icur are based on assumptions beyond our dataset; they illustrate the sensitivity of icur to prosthesis life-cycle assumptions. the calculations show the importance of the parameters such as prosthesis life-cycle and stress the importance of future studies evaluating long-term outcomes. also, development of a quality-of-life measurement instrument that is more sensitive to prosthesis-specific outcomes, to be translated into a utility value, would be a big step forward in evaluating the cost-effectiveness of prostheses. declaration of conflicting interests the authors have no conflicts of interest to declare. references 1.bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and nonmicroprocessor controlled prosthetic knees. can prosthet orthot j. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.4582 2.brüggenjürgen b, riemer a, gapp m. letter to the editor regarding "health economic evaluation of microprocessor and nonmicroprocessor-controlled prosthetic knees". can prosthet orthot j. 2025; volume 8, issue 2, no. 6. https://doi.org/10.33137/cpoj.v8i2.46339 * corresponding author: professor henk groen, affiliation: department of epidemiology, university of groningen, university medical center groningen, groningen, the netherlands. e-mail: h.groen01@umcg.nl orcid id: https://orcid.org/0000-0002-6629-318x open access citation bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. response to the letter to the editor regarding “health economic evaluation of microprocessor and nonmicroprocessor-controlled prosthetic knees”. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 7. https://doi.org/10.33137/cpoj.v8i2 .46486 keywords lower limb; amputation; prostheses; cost analysis; quality of life; questionnaire; mobility; microprocessor knee; cost-effectiveness. journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 2, article no. 7. 2025 https://doi.org/10.33137/cpoj.v8i2.46486 https://doi.org/10.33137/cpoj.v8i2.4582 https://doi.org/10.33137/cpoj.v8i2.46339 https://orcid.org/0000-0002-6629-318x https://doi.org/10.33137/cpoj.v8i2.46486 https://doi.org/10.33137/cpoj.v8i2.46486 https://jps.library.utoronto.ca/index.php/cpoj/index all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 2 2022 editorials raschke s.u. technology management as a core component of a client-centric prosthetic orthotic practice model. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.1. https://doi.org/10.33137/cpoj.v5i2.39001 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i2.39001 1 raschke s.u. technology management as a core component of a client-centric prosthetic orthotic practice model. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.1. https://doi.org/10.33137/cpoj.v5i2.39001 editorials technology management as a core component of a client-centric prosthetic orthotic practice model raschke s.u. * british columbia institute of technology (bcit), 3700 willingdon avenue, burnaby, british columbia, canada. technological innovation has transformed how we communicate, work and conduct business over the past two decades and is now visibly evolving the health care sector. technology translating into health includes: data collection tools, smart technology, new communication platforms and additive manufacturing, with the objectives of improving access to care, outcomes and productivity. the new technology also potentially supports the concept of personalized medicine and creating opportunities for patients to becoming actively engaged in health care decisions as a client-patient. over the next decade, additional tools will be developed that will significantly change how we experience health care both as a health care professional and as the client-patient. being device oriented, prosthetics and orthotics (p&o) examples are commonly cited as what transformative technology in health looks like, with examples ranging from exoskeletons, to microprocessor-controlled components, to sensors and the ever-popular 3d printing (additive manufacturing) of prosthetic and orthotic devices. all consistently capture the attention of the media and imagination of the public.1 a range of the hands-on activities once done manually by the prosthetist orthotist are becoming digitalized and data driven through the use of practice management software, clinical outcome measures, scanners, digitizers and remote fabrication options. in parallel, the palette of componentry and device deigns available to address a client-patient’s needs are expanding rapidly to include highly sophisticated and complex components, such as sensors giving sensory feedback, alongside simpler approaches such as comparatively low cost and easy to fit supportive smart apparel that replaces a number of hard orthotic brace designs. these changes present both an opportunity and a challenge to prosthetists orthotists. extensive effort was made to update prosthetic orthotic education over the past two decades in many countries globally. the changing curriculum typically emphasised the development of a solid, deeper and broader understanding of the clinical aspects of prosthetics orthotics. the same emphasis was not given to open access volume 5, issue 2, article no.1. 2022 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract technological innovation has transformed how we communicate, work, and conduct business. over the next decade how we experience health care both as health care professionals and as client-patients will also change significantly. this presents both an opportunity and a challenge to medical clinical professionals that are device-focused, including prosthetists orthotists, as they consider how best to adapt. current prosthetic orthotic education and practice is heavily clinically weighted, with less emphasis being given to engineering and business skills. yet all three are essential core elements of a successful, sustainable prosthetics orthotics practice. furthermore, it is the latter two that will heavily influence the future face of prosthetics & orthotics. it is not certain how current prosthetic orthotic practitioners can best adapt in response. one solution, proposed in this editorial, could be by rebalancing their professional persona to equally weight the three essential core elements. the result, a clinical prosthetic orthotic technology management professional, would engage in a professional practice that is functionally grounded, uses a client-centric model and incorporate eight professional attributes: professional, advocate, scholar, leader, communicator, collaborator, assistive technology expert and business justification specialist. citation raschke s.u. technology management as a core component of a client-centric prosthetic orthotic practice model. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.1. https://doi.org/10.33137/cpoj.v5i2.39001 keywords orthosis, prosthesis, 3d printing, prosthetics, orthotics, funding, economic, health care, assistive technology, * corresponding author silvia ursula raschke, phd, editor-in-chief british columbia institute of technology (bcit), 3700 willingdon avenue, burnaby, british columbia, canada. e-mail: silvia_raschke@bcit.ca orcid id: https://orcid.org/0000-0001-7964-4295 https://doi.org/10.33137/cpoj.v5i2.39001 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v5i2.39001 mailto:silvia_raschke@bcit.ca https://orcid.org/0000-0001-7964-4295 2 raschke s.u. technology management as a core component of a client-centric prosthetic orthotic practice model. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.1. https://doi.org/10.33137/cpoj.v5i2.39001 issn: 2561-987x technology management in prosthetics and orthotics raschke s.u, 2022 cpoj broadening and deepening the knowledge base supporting prosthetic orthotic design and engineering principles or on the critical economic and business complexities which govern the prosthetics orthotics market. in hindsight, this overemphasis on one of what are three core elements that are required for the successful and sustainable practice of prosthetics orthotics, has made the sector vulnerable to disruption by external forces with skills and expertise in the two underemphasized elements. the dilemma presented by this imbalance became visible to the bcit make+ applied research group as early as 2015. having been using 3d printers in medical and assistive device prototyping since 2001 we saw a sharp increase of potential clients seeking to engage us to apply 3d printing to the production of orthotic devices, citing known challenges with the current provider model and untapped market potential. they had identified prosthetics orthotics as a sector ready for disruption. to explore the opportunity further, a workshop was held inviting a small, international group of engineering and clinical prosthetic orthotic academics, alongside end user representatives, to grapple with how emerging technologies could impact current device provision processes and business models using a swot (strength, weakness, opportunity, threat) model. it was during this day that one of our facilitators commented: “it seems to me that your problem is one of technology management”. the ensuing discussion stayed with me. he did not mean that emerging tools and technologies were a problem to be managed. what he meant was that prosthetist orthotist’s ability to adopt and mange new technology was key to the sector surviving and thriving. a clear threat identified that day was that technology innovation well beyond 3d printing was allowing non-traditional actors to insert themselves into the provision process by creating potentially better designs at lower price points – a legitimately attractive value proposition to payors. his pointed out that the traditional value proposition of the prosthetist orthotist has been that they are the best, or most knowledgeable person, to accompany the client-patient on the path from prescription to receiving a functioning and well-fitting device. this was a reasonable assumption at a time, when the device production process required specialized skills and equipment along with access to prosthetic orthotic components from component manufacturers who only sold them to recognized prosthetists orthotists. the result was an ecosystem that was easy to control, as long as payors continued to accept that value proposition. unfortunately, the proposition was vulnerable at two of the three core elements identified above; vulnerabilities which had been identified as opportunities by the tech development community. unless prosthetists orthotists begin to develop strengths in those two underemphasized core elements, maintaining the current model will become challenging. the next evolution of health care is being carried out by well funded teams of technical experts working with tech sector business strategists and is attracting the attention of large companies and investment funds that previously had not been active in the medical device sector.2,3 device-based and fee-for-device elements of the health care system have been identified as ideally situated for positive disruption. engineers and industrial designers have become recognized as partners in improving health care delivery as technology-based solutions begin to permeate every aspect of health care under what has been identified as medicine 4.0.4 it is difficult for small professions to keep pace with such co-ordinated and well funded impetus, to say little of maintaining control and attempting to guide it. given the unavoidability of this newly developing ecosystem, the facilitator suggested that there is the potential for prosthetist orthotist to secure their place proactively by proposing a new value proposition and repositioning themselves as “technology managers”. this repositioning would see the role of the prosthetist orthotist broaden slightly from a medical-clinical focus to one that also guides client-patients in navigating the increasing number of technology options, which will come in a range of price points, to arrive at optimized and affordable solution for a client-patient. the final solution arrive at might take the form of a custom made and fitted device or might not. such a repositioning would not require abandoning the current clinical role of the prosthetist orthotist. instead, it would be a re-balancing of their professional identity to include, with equal emphasis, all three core elements of the prosthetic orthotic provision model identified above. it would also reduce the fear associated with new technologies disrupting the current provision model and dampen frustrations linked to the reimbursement process. strengthening competencies in the two weak core elements will allow prosthetist orthotists to master those core elements, as opposed to being controlled by them. such a shift is not outside the realm of possibility, with a number of sources already pointing in directions compatible with such a rebalancing. without being explicitly stated as part of a client-centric care model, technology management is already, informally, an ad hoc part of the device provision process. in a recent professional opinion written by dr. chris hovorka (2022) it is proposed that the next generation of prosthetic orthotic education will be based on a curriculum that is functionally focused, as opposed to disease or condition focused, using the world health organization’s (who) international classification of functioning, disability and health (icf) model.5 he suggests informing such a framework with the prosthetic and orthotic practice (pop) model described by jahn and ramsted,6 who describe a model for how icf can be applied within prosthetic orthotic curriculum and practice. finally, he suggests adopting the six key attributes from the competency based medical education framework developed by the royal college of physicians and surgeons of canada as part of their competence by design https://doi.org/10.33137/cpoj.v5i2.39001 3 raschke s.u. technology management as a core component of a client-centric prosthetic orthotic practice model. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.1. https://doi.org/10.33137/cpoj.v5i2.39001 issn: 2561-987x technology management in prosthetics and orthotics raschke s.u, 2022 cpoj initiative (canmeds)7 into the prosthetic orthotic professional persona. these are: professional, advocate, scholar, leader, communicator and collaborator, and have been identified as components necessary for physicians to serve their client-patients well. considering the threats and stressors to the current prosthetics orthotics practice models identified in the 2018 bcit workshop, it could be proposed that two further attributes specific to the prosthetic provision process should be added, namely, assistive technology expert and business justification specialist. an amalgam of the above would create a new practice model that could be described as a clinical prosthetic orthotic technology management professional, encompassing all three core elements of a successful and sustainable prosthetic orthotic provision process with equal weight and competency. as a client-centric model it recognizes what prosthetists orthotists already do, strengthens the two weak core practice elements that currently leave the sector vulnerable to disruption and does so using an inclusive model which engages the clientpatient in decision making and cocreation processes.8 it remains to be seen what the future will bring, but what is already clear is that all device-based health services will require a high level of technology management activities, whether officially recognized and supported or not. acknowledgements none. declaration of conflicting interests dr. silvia raschke is a member of the midwestern university’s advisory board for the prosthetics and orthotics m.sc. program as of spring 2022 and in this capacity has participated in discussions that may have influenced her opinions on this topic. these opinions and ideas expressed in the editorial are those of dr. raschke and have not been reviewed by or endorsed by midwestern university. sources of support none. references 1.birrill i. 3d-printed prosthetic limbs: the next revolution in medicine [internet]. the guardian, 2017; [cited 2022 july 5] available from: https://www.theguardian.com/technology/2017/feb/19/3d-printedprosthetic-limbs-revolution-in-medicine 2.parsons c. data, data everywhere: why the medical device industry must embrace the fourth industrial revolution [internet]. medical design briefs, 2018; [cited 2022, july 5]. available from: https://www.medicaldesignbriefs.com/component/content/article/m db/features/articles/29115 3.saunders s. revenue from 3d printed prosthetics, orthotics, & audiology to reach nearly $1b by 2030, says smartech analysis [internet]. 3dprint.com, 2021; [cited 2022, july 5], available from: https://3dprint.com/283008/revenue-from-3d-printed-prostheticsorthotics-audiology-to-reach-nearly-1b-by-2030-says-smartechanalysis/ 4.popov vv, kudryavtseva ev, kumar katiyar n, shishkin a, stepanov si, goel s. industry 4.0 and digitalisation in healthcare. materials. 2022; 14;15(6):2140. doi: 10.3390/ma15062140 5.hovorka, c. o&p education: guiding the transition to client-centric training [internet]. the o&p edge, 2022; [cited 2022, july 5], available from: https://opedge.com/op-education-guiding-thetransition-to-client-centric-training/ 6.jarl g, ramstrand n. a model to facilitate implementation of the international classification of functioning, disability and health into prosthetics and orthotics. prosthet orthot int. 2018;42(5):468-475. doi:10.1177/0309364617729925 7.frank jr, snell l, sherbino j, editors. canmeds 2015physician competency framework. ottawa: royal college of physicians and surgeons of canada; 2015. isbn: 978-1-926588-28-5 8.desmond d, layton n, bentley j, boot fh, borg j, dhungana bm, et al. assistive technology and people: a position paper from the first global research, innovation and education on assistive technology (great) summit. disabil rehabil: assist technol. 2018;13:5,437-444.doi: 10.1080/17483107.2018.1471169 https://doi.org/10.33137/cpoj.v5i2.39001 https://www.theguardian.com/technology/2017/feb/19/3d-printed-prosthetic-limbs-revolution-in-medicine https://www.theguardian.com/technology/2017/feb/19/3d-printed-prosthetic-limbs-revolution-in-medicine https://www.medicaldesignbriefs.com/component/content/article/mdb/features/articles/29115 https://www.medicaldesignbriefs.com/component/content/article/mdb/features/articles/29115 https://3dprint.com/283008/revenue-from-3d-printed-prosthetics-orthotics-audiology-to-reach-nearly-1b-by-2030-says-smartech-analysis/ https://3dprint.com/283008/revenue-from-3d-printed-prosthetics-orthotics-audiology-to-reach-nearly-1b-by-2030-says-smartech-analysis/ https://3dprint.com/283008/revenue-from-3d-printed-prosthetics-orthotics-audiology-to-reach-nearly-1b-by-2030-says-smartech-analysis/ https://opedge.com/op-education-guiding-the-transition-to-client-centric-training/ https://opedge.com/op-education-guiding-the-transition-to-client-centric-training/ all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 4, issue 2 2021 stakeholder perspectives frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 this article has been invited and reviewed by co-editor-in-chief, dr. silvia ursula raschke. english proofread by: karin ryan, m.a., b.sc., p.t. managing editor: dr. hossein gholizadeh special issue https://online-publication.com/wp/ https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v4i2.36364 https://jps.library.utoronto.ca/index.php/cpoj/editorinchief https://ca.linkedin.com/in/hosseingholizadeh 1 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 stakeholder perspectives trends and opportunities in health economic evaluations of prosthetic care innovations frossard l1-4* 1 yourresearchproject pty ltd, brisbane, australia. 2 griffith university, gold coast, australia. 3 university of the sunshine coast, maroochydore, australia. 4 queensland university of technology, brisbane, australia. introduction alfred nobel (1833-1896) said the following about innovation “if i have a thousand ideas and only one turns out to be good, i am satisfied.” in healthcare, the difference between a “good” or a not so good innovation is made during health technology assessment (hta) and/or health economic evaluation (hee).1 as defined in appendix 1, these evaluations aim at understanding what is the value for money of a treatment. simply put, payers want to make sure they get a bang for their buck! this is tough question because the answer is rarely black and white. nonetheless, addressing any concerns with socio-economical value of an intervention is a prerequisite to warrant access to market. great but unaffordable treatments have little prospect of being adopted by healthcare policymakers. the paper deals with issues of health economic assessments specific to prosthetic care innovations as open access volume 4, issue 2, article no.9. 2021 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index abstract overcoming obstacles to prosthetic fittings requires frequent tryouts of sockets and components. repetitions of interventions are upsetting for users and place substantial economic burden on healthcare systems. encouraging prosthetic care innovations capable of alleviating clinical and financial shortcomings of socket-based solutions is essential. nonetheless, evidence of socioeconomic benefits of an innovation are required to facilitate access to markets. unfortunately, complex decisions must be made when allocating resources toward the most relevant health economic evaluation (hee) at a given stage of development of an innovation. this paper first, aimed to show the importance and challenges of hees of intervention facilitating prosthetic fittings. next, the main trends in hees at various phases of product development and clinical acceptance of prosthetic care innovations were outlined. then, opportunities for a basic framework of a preliminary cost-utility analysis (cua) during the mid-stage of development of prosthetic care innovations were highlighted. to do this, fundamental and applied health economic literature and prosthetic-specific publications were reviewed to extract and analyse the trends in hees of new medical and prosthetic technologies, respectively. the findings show there is consensus around the weaknesses of full cuas (e.g., lack of timeliness, resource-intensive) and strengths of preliminary cuas (e.g., identify evidence gaps, educate design of full cua, fast-track approval). however, several obstacles must be overcome before preliminary cua of prosthetic care innovations will be routinely carried out. disparities of methods and constructs of usual preliminary cua are barriers that could be alleviated by a more standardized framework. the paper concludes by identifying that there are opportunities for the development of a basic framework of preliminary cua of prosthetic care innovations. ultimately, the collaborative design of a framework could simplify selection of the methods, standardise outcomes, ease comparisons between innovations and streamline pathways for adoption. this might facilitate access to economical solutions that could improve the life of individuals suffering from limb loss. citation frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 keywords artificial limbs, bionic limbs, boneanchored prosthesis, costeffectiveness, cost-utility, health economic evaluation, health technology assessment, prosthesis, socket-suspended prosthesis * corresponding author laurent frossard (phd), professor of bionics yourresearchproject pty ltd, brisbane, australia. e-mail: laurentfrossard@outlook.com orcid number: https://orcid.org/0000-0002-0248-9589 special issue: health economics in prosthetics & orthotics https://doi.org/10.33137/cpoj.v4i2.36364 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.33137/cpoj.v4i2.36364 mailto:laurentfrossard@outlook.com https://orcid.org/0000-0002-0248-9589 2 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e presented in figure 1. first, the importance and challenges of hees of interventions facilitating prosthetic fittings are highlighted. next, the main trends in hees of new healthcare technologies are outlined with particular emphasis on specific hees to consider during the course of development of innovations. then, opportunities for a basic framework of preliminary assessments during the mid-stage of development of prosthetic care innovations are suggested. finally, the paper concludes with some calls to action to further develop preliminary assessments. importance of health technology evaluations this introductory section highlighted (a) the needs for solutions facilitating prosthetic fittings and (b) the current challenges to produce relevant health economic evaluations of prosthetic care innovations. role of prosthetic care because the everyday ability of individuals suffering from limb loss to use an artificial limb is critical to their quality of life, clinical teams made bespoke recommendations intending to maximize comfort, stability and mobility of prosthetic fittings.2,3 ultimately, this process incorporates all personalized interventions performed by a prosthetist around the choice and alignment of prosthetic components as well as the management of prosthetic attachment to the residuum including design, manufacture and adjustment of socket or osseointegrated implant.4 outcomes of prosthetic fitting depends largely on the performance of prosthetic components.5-11 where dillingham et al (2001) noted that 60% of amputees are satisfied with prosthetic characteristics such as weight, aesthetics and functionality (e.g. servicing, how easy the prosthesis is to use) and 57% of the traumatic lower limb amputees in the study expressed some dissatisfaction with prosthetic comfort.12 since, studies showed that the use and satisfaction of prosthetic lower limb could be significantly improved when using advanced components such microprocessor-controlled knees compared to a nonmicroprocessor-controlled knees.9,13,14 list of abbreviations cet: cost-effectiveness threshold chec: consensus health economic criteria extended checklist cheer: consolidated health economic evaluation reporting standards checklist cua: cost-utility analysis hee: health economic evaluation hta: health technology assessment icer: incremental cost-effectiveness ratio icur: incremental cost-utility ratio qaly: quality-adjusted life-year sf36: 36-item short form survey wtp: willingness-to-pay threshold trends • generic pathways to hee • prosthetic-specific hee importance • needs for prosthetic care innovations • challenges to produce hee gaps • knowledge gaps of hee • role of pre cua to assess innovation health technology assessment health economy evaluation need for pre cua basic pre cua framework figure 1: overview of importance, trends and gaps of health economy evaluations (hee) of prosthetic solutions leading to the need for basic framework of preliminary (pre) cost-utility analysis (cua) for prosthetic care innovations. https://doi.org/10.33137/cpoj.v4i2.36364 3 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e satisfactory prosthetic fitting might be compromised because of incongruous shapes of residuum (e.g., length, bulbous, volume change) and/or skin issues.15-17 paterno et al (2018) and meulenbelt et al (2009) report that that 63– 82% of lower limb amputees have problems with skin lesions.2,18 turner and mcgregor (2020) report that 48.0% of amputees and 65.7% of clinicians cited socket fit issues as the biggest factor impacting rehabilitation.6 and, sadly, paterno et al (2018) and meulenbelt et al (2009) found a 2557% prosthetic abandonment rate and identified failed socket fit as a likely possible cause.2,18 demand for prosthetic care innovations in many cases, overcoming obstacles to prosthetic fitting requires frequent tryouts of components and sockets fittings.3 regular medical attention are, first and foremost, upsetting (e.g., pain), disruptive (e.g., sick leave) and costly (e.g., out-of-pocket expenses) for users.19 repetitions of interventions also place a substantial economic burden on healthcare systems stressed to subsidize treatments beyond minimal prosthetic care standards.20-22 for example, the fitting of only a single socket per year might be approved by some healthcare organizations.22 encouraging prosthetic care innovations that alleviate the clinical and financial shortcomings of current fitting options is essential (appendix 1).2,3,14,23-26 hence, efforts made by a bench of stakeholders (e.g., users, carers, clinicians, engineers, researchers, administrators) to develop and encourage new prosthetic care interventions to improve socket fittings and, eventually, eliminate socket attachments altogether (e.g., bone-anchored prostheses).27-34 these solution-finders will be called “promoters” of prosthetic care innovations throughout this paper and are shown in relationship to other concepts presented in this paper as a regrouping of individuals suffering from limb loss, providers of prosthetic solutions and administrators of healthcare organisations (appendix 1) into a single collaborative group with common goals.22,35-38 ultimately, prosthetic care innovations must be safe and efficient in ways that alleviate some adverse events (e.g., pain, slippage, pistoning, bell clapping, skin damages, falls), maximise functional outcomes (e.g., comfort, stability, mobility) and, preferably, enhance quality of life (e.g., quality-adjusted life year, disability-adjusted life year).2,3,14,23-25,29,39,40 proofs of safety and efficacy of innovations are essential but no longer sufficient.11 evidence of socio-economic benefits are also paramount.4,30,37,38,41-47 health economic evaluations of innovations ijzerman and steuten (2011) identified that in order for societal benefits to be maximized three things must occur: 1) governments need more data on benefits arising when public resources are spent, 2) companies need more data to effectively manage their product development portfolios and 3) research programs at universities may need to be actively encouraged in this direction.37 policymakers in healthcare organizations around the world adopt a reasoning more or less utilitarian when making decisions about medical care expenses.37 however, healthcare administrators are often obligated to confirm the value for money of interventions prior approval (e.g. fee-forservice, fee-for-value).47-53 for example, an hee might be required to differentiate the four microprocessor-controlled knees assessed by campbell et al (2020) all showing relative parity with regards to functional mobility, health state satisfaction and quality of life or injurious falls (i.e., cleg, ottobock, duderstadt, germany; orion, blatchford group, hampshire, united kingdom; plie, freedom innovations, irvine, california, united states; rheo, ossur, reykjavik, iceland).14 recommendation for one knee or the other may be based on costs reduction of prosthetic care interventions. the burden of hee of an innovation also falls onto developers and manufacturers of technological solutions including attachments (e.g., liners, sockets, implants), artificial limb components (e.g., elbow, wrist, knee, ankle) and protective device (e.g., shock absorbers, failsafe).38 steven et al (2019) suggested that solution developers must understand the value created by their interventions and act quickly on them to provide some forms of evidence of costeffectiveness of their innovations.48 failing to do so could seriously hinder access to market and adoption of their innovations. o’malley (2010) indicated that the most common reason for the australian medical services advisory committee to not recommend funding for new technology was not only insufficient clinical evidence but also the lack of proven cost-effectiveness presented during early stage of the examination process.54 making decisions about economic evaluations steven et al (2019) stated that hee can be approached in a number of ways. they identified a range of approaches to compare the costs of health care services and possible cost savings which observe the consequences of an intervention and the effectiveness of that same intervention through a lens of outcomes that are valued patients, payers and providers, or which align with widely used global utility measures.48 they specified that the value of a prosthetic care intervention could be assessed using a range of costbenefit, cost-consequence, cost-effectiveness and costutility analyses considering valuations of costs (e.g., monetary units) and a range of benefits. ijzerman and steuten (2011) specified that no single method will produce the right information for all decision makers. each method has advantages and disadvantages and work for specific applications, as opposed to all applications.37 they suggested that a toolbox of methods must be used. https://doi.org/10.33137/cpoj.v4i2.36364 4 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e unfortunately, the multitude of hees often leave promoters making challenging decisions around allocation of sufficient resources toward the most relevant hee approach at a given point of an innovation development. facilitating this decision-making process would start with an overview of the trends and specific ways hees can be done at various stages of development of an innovation. current trends in health technology evaluations this second section (a) reviewed generic pathways to assess health economic consequences of a new treatment at a given stage of product development and clinical acceptance and (b) highlighted selected studies that followed these pathways to assess prosthetic care interventions. key concepts of health economic evaluations as described in appendix 1, hee include, but not limited to, cost-effectiveness analyses (cea) or cost-utility analyses (cua). these terms are often used interchangeably although they are technically looking at different types of utilities. ceas are concerned with a particular functional outcome of a treatment (e.g., walking speed). cuas rely on self-reported quality of life status measured using standard surveys such as eq-5d or 36item short form survey (sf36). cuas comparing usual and new treatments involve incremental cost-utility ratio (icur) based on incremental costs and utilities over time that could be compared to cost-effectiveness (cet) or, more often, willingness-to-pay (wtp) thresholds.1,48,55 patient-centred assessments of global health-related quality of life might be influenced by prosthetic care to a certain extent. therefore, these metrics might reflect only partially the benefits of a prosthetic intervention. however, outcomes of cua reported in monetary units per qualityadjusted life-year (qaly) can be easily compared across other medical interventions or disease states. cuas are commonly used to facilitate effective communication among healthcare professionals.48,56,57 health economic evaluations pathways promoters can be informed by an abundance of health economic research focusing on a broad range of fundamental and applied hees issues that could be more or less relevant (e.g., difference between pharmaceutical and medical technologies).54,58 some studies provided valuable insights into ways outcomes of hees can facilitate the approval process of an innovation by a particular governmental healthcare system (e.g., australian).53,54,59-61 others explained the basic concepts of hees to clinicians and prosthetic care providers.48,56,57 several landmark studies presented prosthetic-specific hees.21,50-52,61-74 two studies were of particular interest because they can assist promoters to make an educated decision when choosing an hee accordingly to the level of innovation development. ijzerman and steuten (2011) systematically described that early, preliminary and full cuas can be conducted at the early, mid and late stage of clinical acceptance of any medical treatment, respectively.37 more recently, new insights were provided by kannenberg and seidinger (2019) who explained how these three types of cuas should also be performed by prosthetic manufacturers at early, mid and late phase development of a prosthetic product.38 the authors indicated that cua during the product’s life cycle is beneficial in three ways. it allows potential cost-effectiveness to be estimated and included in investment decision processes and mitigates the risk of investing in technology unlikely to be costeffective. it helps to prioritize between competing costeffective concepts or technologies. it facilitates the identification of parameters having the largest impact on the likely cost-effectiveness of the product to be identified in order to best manage limited research funds.38 figure 2 gives an overview synthesizing both approaches. decision uncertainty and strength of evidence were suggested for early, preliminary and full cuas during early, mid and late phase of product development (manufacturer’s perspective) and clinical acceptance (healthcare’s perspective) of prosthetic care innovations, respectively. next, the general principle, expected capacity to address consolidated health economic evaluation reporting standards (cheers) and consensus health economic criteria (chec) extended checklists, typical strengths and weaknesses as well as selected examples of prostheticfocused cuas.75-77 is briefly described. the decision was made to present the cuas as they historically gained recognition starting from full, to preliminary and early cuas rather than following the sequential timeline of their implementation. appraisal of each type of cuas using the cheers and chec-extended checklists were detailed in supplementary material. full cost-utility analyses traditionally, mainstream hees involved comprehensive or “full” cuas essentially produced when innovations are gaining clinical acceptance after commercialisation. full cuas can be conducted from societal and/or healthcare perspectives. these cuas usually rely on primary costs extracted from financial records expressed in monetary units as well as utilities measured by quality of life surveys expressed in qaly for cohorts of participants over an extended period of time (appendix 1).48,50-53,62,78,79 costs, utilities and icurs are projected using bayesian or markov models based on plausible information extracted from primary studies for a series of scenarios over scalable time horizons (e.g., years, decades, lifetime).1,37,63,64,70,78,80,81 https://doi.org/10.33137/cpoj.v4i2.36364 5 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e it was postulated that conventional full cuas should address strongly all items of the cheers and checextended checklists (table 1,table 2). modelling cuas can be comprehensive because of the breadth (e.g., scenarios) and depth (e.g., time horizon) of their analysis. furthermore, uncertainty and sensibility of outcomes, shown by the size of the errors around the point estimates due to data sources (e.g., sample size) and/or to the process of evaluation (appendix 1), tend to be well worked out and, possibly, relatively low compared to early and preliminary cuas.82 therefore, full cua provide strong evidence supporting robust recommendations considered by decision makers (e.g., approval for funding). however, modelling cuas require substantial resources. building models is labour intensive (e.g., determine scenarios, test assumptions). more importantly, kannenberg and seidinger (2019) noted the necessity of requiring the inclusion of outcome parameters, like healthrelated quality of life, in these models.38 this means that full cuas produce their best outcomes when sufficient costs and utilities are known for large cohorts over an extended length of time in a given jurisdiction (e.g., within-trial and beyond-trial horizon studies).83 evidence-based weak d e c is io n u n c e rt a in ty s tr e n g th o f e v id e n c e low high case-series proof of utility clinical trial cohort study randomized clinical trial early stage health technology assessment mid stage late stage full cua pre cua early cua strong proof of safety proof of efficacy clinical acceptance health economy evaluation product development clinical acceptance figure 2: overview of expected grading of decision uncertainty (i.e., high to low) and strength of evidence (i.e., weak to strong) of early, preliminary (pre) and full cost-utility analysis (cua) conducted during typical health technology assessments at early, mid and late phase of product development (manufacturer’s perspective) and clinical acceptance (healthcare’s perspective) of prosthetic care innovations, respectively. https://doi.org/10.33137/cpoj.v4i2.36364 6 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e developments of new interventions takes time, particularly when the recommended clinical timelines are followed to demonstrate efficiency and safety (e.g., clinical trial registration, ethics approval, surgical learning curve, observation times, design of rehabilitation program). several years might be needed to gather the costs and utilities required to complete primary and modelling cuas. consequently, mainstream cuas can hardly inform promoters timely. lack of timeliness is even more problematic with new prosthetic care technologies that are more susceptible to be superseded after five years.[60] gallego et al (2011) described decisions to approve technology by committees and regulatory bodies, such as the australian medical services advisory committee, typically occurs after the technology has evolved or is already commonly being used in practice.60 ijzerman and steuten (2011) also noted the problems with this approach, warning that many design decisions (e.g. target population, use setting, technology design features such as connectivity with data infrastructure, seamless integration with complementary technology, etc) are made in the early stages of product development and are difficult, expensive and/or impossible to change at a later date.37 several studies used a full cua to assess consequences of the provision of socket based solution including advanced prosthetic components such as microprocessor-controlled knees and energy storing and return feet as well as socketfree solutions including bone-anchored prostheses.21,61,6374 preliminary cost-utility analyses the issue of timeliness of full cuas could be addressed by performing preliminary cuas of innovations that could take place sometimes around the mid-stage of product development when clinical usage is still limited to small cohorts. preliminary cua is an option “in-between” early and full cuas that considered innovations with a broad range of development status. therefore, preliminary cuas can be conducted using a wide spectrum of methods. they can involve primary data of actual (e.g., financial records) and/or simulated (e.g., purposely created schedules) costs expressed in monetary units as well as measured (e.g., quality of life surveys) and/or guesstimated (e.g., literature) utilities expressed in qaly for cohorts of participants over a somewhat lengthy time horizon.48,50-52,62,78,79 the assumption was made that typical preliminary cuas have a weak and moderate capacity to address 9 (33%) and 8 (30%) of items in the cheers checklist, including 7 (44%) and 6 (38%) of items in the methods as well as 2 (40%) and 2 (40%) of items in the results sections, respectively (table 1). it was estimated that preliminary cuas should be capable to address 11 (58%) of items in the chec-extended checklists (table 2). resources needed to conduct preliminary cuas could varied depending on the sources of data considered. estimating costs from schedules and utilities from literature might require less resources than extracting costs from financial systems and utilities from a survey for a cohort of convenient sample size. preliminary cuas can provide some indications of probable consequences of innovations. practically, preliminary cuas can generate primary information, in part or in whole, useful for modelling cuas (e.g., costs and utilities estimates, scenario drafting). however, preliminary cuas are usually built around substantial assumptions based on best-estimates of costs and utilities at the time. typical preliminary cuas are characterised by narrow perspective, simple scenarios, and time horizons tentatively shorter than full cuas. further limitations are inherent to the mismatch of costs and utilities from incongruous jurisdictions, onsets and post-operative timelines. for example, actual costs extracted from an healthcare financial system over several years might be considered against estimated utilities based on studies performed in other countries measuring quality of life six months after the intervention.50-52 finally, uncertainty and sensibility of preliminary cuas might be only loosely considered and reported. altogether, the weight of these limitations on the strength of evidence is less known weakening the recommendations. unfavourable outcomes of preliminary cuas might, at least, question and, possibly, stop further product commercialization and clinical considerations. a decision must be made whether favourable outcomes are deemed sufficient to pursue and eventually, readjust further developments. recent examples of preliminary cuas of innovations looked at the benefits of transfemoral and transtibial boneanchored prostheses from government prosthetic care perspective.50-53 early cost-utility analyses preliminary cuas can provide timelier assessment than full cuas. nonetheless, there is a current trend in health economic literature arguing that preliminary cuas are yet to provide sufficiently timely assessment of innovations. hence, the promotion of early cuas, also called “iterative economic evaluations” or “very early hta” by ijzerman and steuten (2011), which pointed out that attempts have already been made, using “horizon scanning systems”, to include new, emerging technologies into health policy as it is developed. other authors have referred to this as the use of “early warning systems”.37 early cuas tend to be constructed like preliminary cuas but they rely more heavily on sparser costs and utilities data as well as sketchier assumptions. these analyses tend to be based on best guestimates of most likely costs and utilities collected with case-series studies and/or extracted from the literature often produced outside the relevant jurisdiction. https://doi.org/10.33137/cpoj.v4i2.36364 7 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e table 1: expected capacity (i.e., weak, moderate, strong) of typical early, preliminary (pre) and full cost-utility analysis (cua) to address the 27-item of the consolidated health economic evaluation reporting standards (cheers) checklist. section and item number recommendation cua early pre full title and abstract title 1 identify the study as an economic evaluation or use more specific terms such as “cost-effectiveness analysis”, and describe the interventions compared. strong strong strong abstract 2 provide a structured summary of objectives, perspective, setting, methods (including study design and inputs), results (including base case and uncertainty analyses), and conclusions. strong strong strong introduction background and objectives 3 provide an explicit statement of the broader context for the study. present the study question and its relevance for health policy or practice decisions. strong strong strong methods target population and subgroups 4 describe characteristics of the base case population and subgroups analysed, including why they were chosen. moderate moderate strong setting and location 5 state relevant aspects of the system(s) in which the decision(s) need(s) to be made. moderate strong strong study perspective 6 describe the perspective of the study and relate this to the costs being evaluated. weak moderate strong comparators 7 describe the interventions or strategies being compared and state why they were chosen. weak moderate strong time horizon 8 state the time horizon(s) over which costs and consequences are being evaluated and say why appropriate. moderate moderate strong discount rate 9 report the choice of discount rate(s) used for costs and outcomes and say why appropriate. weak weak strong choice of health outcomes 10 describe what outcomes were used as the measure(s) of benefit in the evaluation and their relevance for the type of analysis performed. weak weak strong measurement of effectiveness 11a single study-based estimates: describe fully the design features of the single effectiveness study and why the single study was a sufficient source of clinical effectiveness data. weak weak strong 11b synthesis-based estimates: describe fully the methods used for identification of included studies and synthesis of clinical effectiveness data. weak weak strong measurement and valuation of preference based outcomes 12 if applicable, describe the population and methods used to elicit preferences for outcomes. weak weak strong estimating resources and costs 13a single study-based economic evaluation: describe approaches used to estimate resource use associated with the alternative interventions. describe primary or secondary research methods for valuing each resource item in terms of its unit cost. describe any adjustments made to approximate to opportunity costs. weak weak strong 13b model-based economic evaluation: describe approaches and data sources used to estimate resource use associated with model health states. describe primary or secondary research methods for valuing each resource item in terms of its unit cost. describe any adjustments made to approximate to opportunity costs. weak weak strong currency, price date, and conversion 14 report the dates of the estimated resource quantities and unit costs. describe methods for adjusting estimated unit costs to the year of reported costs if necessary. describe methods for converting costs into a common currency base and the exchange rate. strong strong strong choice of model 15 describe and give reasons for the specific type of decision analytical model used. providing a figure to show model structure is strongly recommended. moderate strong strong assumptions 16 describe all structural or other assumptions underpinning the decision-analytical model. weak moderate strong analytical methods 17 describe all analytical methods supporting the evaluation. this could include methods for dealing with skewed, missing, or censored data; extrapolation methods; methods for pooling data; approaches to validate or make adjustments (such as half cycle corrections) to a model; and methods for handling population heterogeneity and uncertainty. weak moderate strong https://doi.org/10.33137/cpoj.v4i2.36364 8 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e table 1 (continued). section and item number recommendation cua early pre full results study parameters 18 report the values, ranges, references, and, if used, probability distributions for all parameters. report reasons or sources for distributions used to represent uncertainty where appropriate. providing a table to show the input values is strongly recommended. weak moderate strong incremental costs and outcomes 19 for each intervention, report mean values for the main categories of estimated costs and outcomes of interest, as well as mean differences between the comparator groups. if applicable, report incremental cost-effectiveness ratios. strong strong strong characterising uncertainty 20a single study-based economic evaluation: describe the effects of sampling uncertainty for the estimated incremental cost and incremental effectiveness parameters, together with the impact of methodological assumptions (such as discount rate, study perspective). weak moderate strong 20b model-based economic evaluation: describe the effects on the results of uncertainty for all input parameters, and uncertainty related to the structure of the model and assumptions. weak weak strong characterising heterogeneity 21 if applicable, report differences in costs, outcomes, or cost effectiveness that can be explained by variations between subgroups of patients with different baseline characteristics or other observed variability in effects that are not reducible by more information. weak weak strong discussion study findings, limitations, generalisability, and current knowledge 22 summarise key study findings and describe how they support the conclusions reached. discuss limitations and the generalisability of the findings and how the findings fit with current knowledge. strong strong strong other source of funding 23 describe how the study was funded and the role of the funder in the identification, design, conduct, and reporting of the analysis. describe other non-monetary sources of support. strong strong strong conflicts of interest 24 describe any potential for conflict of interest of study contributors in accordance with journal policy. in the absence of a journal policy, we recommend authors comply with international committee of medical journal editors recommendations. strong strong strong table 2: expected capacity (i.e., yes, no) of typical early preliminary (pre) and full cost-utility analysis (cua) to address the 19-item consensus health economic criteria (chec) extended checklist. item questions cua early pre full 1 is the study population clearly described? yes yes yes 2 are competing alternatives clearly described? yes yes yes 3 is a well-defined research question posed in answerable form? yes yes yes 4 is the economic study design appropriate to the stated objective? yes yes yes 5 is the chosen time horizon appropriate in order to include relevant costs and consequences? no no yes 6 is the actual perspective chosen appropriate? yes yes yes 7 are all important and relevant costs for each alternative identified? no no yes 8 are all costs measured appropriately in physical units? yes yes yes 9 are costs valued appropriately? no no yes 10 are all important and relevant outcomes for each alternative identified? no no yes 11 are all outcomes measured appropriately? no no yes 12 are outcomes valued appropriately? no no yes 13 is an incremental analysis of costs and outcomes of alternatives performed? no yes yes 14 are all future costs and outcomes discounted appropriately? no no yes 15 are all important variables, whose values are uncertain, appropriately subjected to sensitivity analysis? no no yes 16 do the conclusions follow from the data reported? yes yes yes 17 does the study discuss the generalizability of the results to other settings and patient/client groups? yes yes yes 18 does the article indicate that there is no potential conflict of interest of study researcher(s) and funder(s)? yes yes yes 19 are ethical and distributional issues discussed appropriately? yes yes yes https://doi.org/10.33137/cpoj.v4i2.36364 9 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e it was assumed that usual early cuas have a weak capacity to address 15 (56%) of items in the cheers checklist including 11 (69%) of items in the methods as well as 4 (80%) of items in the results sections (table 1). preliminary cuas might be incapable to address up to 9 (47%) of items in the chec-extended checklists (table 2). early cuas are affordable and timely. they could help to reduce or validate assumptions subsequently used in preliminary or modelling cuas. perhaps, the most valuable return on investment of early cuas is to provide insight into the viability of the product and worthiness of the clinical introduction on an innovation, as described by kannenberg and seidinger (2019).38 as expected, outcomes of early cuas are likely to have high uncertainty and sensibility leading to low level of evidence and only tentative recommendations. early evidence of potential cua might fast-track on-going innovation development. limited prospects of cua might raise questions about further allocation of resources to a product that has, ultimately, minimal chance to meet payer’s expectations. gaps in earlier health economic evaluations this last section (a) presented the current consensus and knowledge gaps around earlier hees and (b) highlighted opportunities for developments of a basic framework of preliminary cua. benefits of earlier health economic evaluations there is consensus around the weaknesses of full cuas (e.g., lack of timeliness, resource-intensive) and strengths of early and preliminary cuas, summarised in table 3. earlier cuas have the potential to assist promoters to: • identify evidence gaps and headroom for improvements that generate insights into potential capacity of an innovation to alleviate the financial burden of prosthetic fittings.37,50-52 • educate the design of primary and modelling studies including the planning (e.g., calculate statistical power, determine of sample size, obtain ethics approval), collection (e.g., mine data from financial records, design table 3: typical strengths and weaknesses of the early, preliminary, and full cost-utility analyses (cua) of prosthetic care innovations. strengths weaknesses full cua • address strongly all 27 cheers items • capable to address all 19 chec items • comprehensive list of scenarios • scalable time horizon • strong understanding of uncertainty • strong understanding of sensibility • high level of evidence • strong recommendations • need of primary costs and utilities data • require substantial resources • lack of timeliness preliminary cua • address strongly 37% of cheer items • capable to address 58% of chec items • timeliness of information • identify evidence gaps • provide headroom for improvement • capable to generate primary data • educate design of full cuas • fast-track approval • address weakly 33% of cheer items • uncapable to address 42% of chec items • variability of resources required • build around substantial assumptions • rely on best-known evidence • consider narrow perspective • consider plausible scenarios, • consider mid-term time horizon • mismatch costs and utilities data • limited understanding of uncertainty • limited understanding of sensitivity • moderate level of evidence • moderate strength of recommendations early cua • address strongly 30% of cheer items • capable to address 53% of chec items • require little resources • timeliness of information • early insights into product viability • early insights into clinical worthiness • identify evidence gaps • provide headroom for improvement • educate design of preliminary cuas • facilitate fast-track approval • address weakly 56% of cheer items • uncapable to address 47% of chec items • build around substantial assumptions • rely on best-known evidence • consider narrow perspective • consider hypothetical scenarios, • consider short-term time horizon • rely of expected costs and utilities data • low understanding of uncertainty • low understanding of sensitivity • low level of evidence • low strength of recommendations https://doi.org/10.33137/cpoj.v4i2.36364 10 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e databases) and analysing (e.g., build model, draft scenarios, choose assumptions).47 • fast-track approval from governing bodies like australian medical services advisory committee. gallego et al (2011) said that earlier cuas can help to prioritize in which order new technologies are evaluated and allows for the fast-tracking of technologies which either have a least potential for harm or which have a great potential to benefit patients.54,60 obstacles to earlier health economic evaluations ijzerman and steuten (2011) pointed out that the emerging field of hta research will likely gain prominence as it will help navigate the increasingly complex trade-offs that must be considered when making investments in medical product development and ensuring access to those products.37 however, earlier cuas are far from being widely considered when developing new prosthetic solutions. several obstacles must be overcome before earlier and, more particularly, preliminary cuas of prosthetic care innovations would be routinely carried out by promoters. one critical obstacle is the abundance of methods. ijzerman and steuten (2011) listed ten quantitative methods that could be used in earlier hta (e.g., payback from research analysis, strategic business cases, health impact assessment, multi-criteria decision methods, choice-based preference methods, real options analysis, early health economic modelling, horizon scanning systems, clinical trial simulation, value-of-information analysis).37 another obstacle is the multiple pathways for hee relying on the same level of clinical evidence of utilities (figure 2). logically, early and full cuas are indicated at early stage and after clinical acceptance, respectively. initial clinical evidence provided by proof of utility and case-series could be used to perform an early and preliminary cuas. stronger evidence gathered during cohort study and clinical trial might be deemed sufficient to conduct a preliminary or full cuas. disparities of methods and constructs of earlier cuas (e.g., perspective, time horizon, discount, uncertainty, sensibility) have ripple effects limiting implementation of earlier cuas. cross-comparing outcomes of earlier cuas between innovations might be challenging to interpret. generalization of outcomes across healthcare organisations might be limited. earlier cuas might show a broad level of quality when appraised with standard cheers and chec-extended checklists, primarily designed for full cuas (table 1, table 2). altogether, disparity of outcomes also makes earlier cuas scoring modestly in these checklists less likely to be published. the result of this is a sparsity of publications in prostheticfocused scientific journals, let alone heath economics journals, the latter of which are inclined to consider that socio-economic research in prosthetics is for a niche audience. literature review and meta-analyses of health economic evaluations failing to stratify publications accordingly to the three types of cuas might appraise unfavourably the contribution of earlier cuas.84,85 therefore, this review might skew the perception on the overall quality of health economic evaluations of prosthetic care. earlier cuas might score less not because they are poorly done but because they are dealing with more unreliable datasets. opportunities for basic framework of preliminary cua on a one side, every innovation is different. each healthcare organisation has particular expectations. promoters might choose a specific pathway for a given cua depending on their confidence to make valid assumptions. therefore, a preliminary cua of an innovation could be unique. one the other side, provision of prosthetic care follows a rather standardized process. reimbursement are often made for categories of components (e.g., microprocessorcontrolled knees.14 prosthetists performed series of wellidentified specific tasks related to prosthetic fitting (e.g., fitting of socket, choice of components, alignment of prosthesis), assessment of outcomes (e.g., comfort, stability, mobility) and reporting to payers (e.g., reimbursement claims).47 indeed, each of these tasks is sufficiently codified to be individually supported by healthcare organisations (e.g., l-codes). this means that most preliminary cuas relying on estimated rather than primary costs could apply a template of schedule of allowable expenses. this typical matrix can present costs at the intersections of list of tasks in rows and timeline of interventions in columns (appendix 1). ideally, disruptive and economical innovations changing best prosthetic care practice should affect a schedule by reducing the price tag and/or the frequency of one or more tasks. furthermore, standard assessments are commonly used to quantify outcomes of prosthetic fittings using self-reported satisfaction (e.g., orthotics and prosthetics user's survey, quebec user evaluation of satisfaction with assistive technology, socket prosthetic comfort score), physical tasks (e.g., berg balance scale, timed get-up and go, walking speed, 2-minute walk, 6-minute walk, functional ambulation profile, amputee mobility predictor with prosthesis) as well as specific (e.g., questionnaire for persons with a transfemoral amputation) and generic (e.g., eq-5d, sf36) health-related quality of life with an innovation.12,13,29,86 altogether, organisation of the delivery and assessment of prosthetic care might be sufficiently transferable across innovations to consider a more uniform approach to preliminary cuas.50-52 this creates opportunities to explore the development of a basic framework including set https://doi.org/10.33137/cpoj.v4i2.36364 11 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e constructs (e.g., perspective, time horizon, discount) and practical recommendations (e.g., funding cycles) specific to preliminary cuas of the prosthetic care innovations (appendix 1). this new approach to a preliminary cua has the potential to simplify the selection of methods, standardise outcomes, ease comparisons between innovations and streamline pathways for adoption while facilitating the production of a body of literature on prosthetic health economics. conclusion this work showed that promoters must make complex decisions when attempting to establish the socio-economic values of prosthetic care innovations. it is commonly acknowledged that a unique type of cua could not be applied at every stage of development of an innovation. preliminary cuas of innovations at the mid-stage of development is particularly valuable but challenging. boundaries delineating preliminary cuas from early and full cua might be blurry pushing promoters to consider a wide range of methods. the outcomes suggest that there are opportunities for collective design of a basic framework of a preliminary cua of prosthetic care innovations. however, reaching consensus around a framework can be challenging because there is no formal forum capable to organise discussions outside of usual scientific peer-review channels. there is a need for an ad-hoc reference group involving promoters and heath economists specialized in prosthetics and medical aids. ideally, this working group should be hosted by international (e.g., world health organisation standards for prosthetics and orthotics service provision, international society for prosthetics and orthotics) or national (e.g., american orthotic and prosthetic association, center for orthotic and prosthetic learning and outcomes/evidence-based practice) governing bodies. its missions could be to develop guidelines and, possibly, standards of hees of prosthetic care interventions including preliminary cuas frameworks (e.g., set constructs, practical recommendations). ultimately, a wide adoption of a this collegial preliminary cua framework will, hopefully, contribute to promote the routinely used preliminary cua. it is anticipated that this framework should facilitate access to economical prosthetic care solutions improving the life of individuals suffering from limb loss worldwide. call to action • gather an ad-hoc reference group capable of (a) monitoring the current trends in hees of new healthcare technologies, (b) develop guidelines and, possibly, standards of hees of prosthetic care interventions, (c) promote the adoption of these guideline (e.g., publications of position papers, presentations at conferences). • this working group could facilitate discussions between promoters of prosthetic care innovations around the use and validation of preliminary cuas frameworks. • practically, these discussions should focus on the development of basic framework of a preliminary cuas, more particularly set constructs and practical recommendations. acknowledgements the author wishes to express his gratitude to debra berg and gregory merlo for their support. declaration of conflicting interests the author is in the view that these competing interests do not conflict with the content of this manuscript. laurent frossard, director and chief scientist officer of yourresearchproject pty ltd, has worked as consultant for several organisations on non-related educational programs and projects of research focusing on recording loading data, developing of database to record clinical outcomes as well as drafting grants and manuscripts for cognitive institute, exercise & sports science australia, griffith university, ipug pty ltd, middlesex university, new zealand artificial limb service, osseointegration group of australia pty ltd, ossur, poly-orthodox international, queensland artificial limb service, queensland university of technology, return to work-south australia, south australia health, tequir s.l, university of the new south whales, university of the sunshine coast. sources of support this study was funded by yourresearchproject pty ltd. references 1.tan-torres edejer t, baltussen r, adam t, hutubessy r, acharya a, evans db, et al. who guide to cost-effectiveness analysis [internet].world health organisation. 2003; [cited 2021, june 9]. available from: https://www.who.int/choice/publications/p_2003_generalised_cea. pdf?ua=1dfid 2.paternò l, ibrahimi m, gruppioni e, menciassi a, ricotti l. sockets for limb prostheses: a review of 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doi: 10.21300/18.2-3.2016.175 17.gholizadeh h, abu osman na, eshraghi a, arifin n, chung ty. a comparison of pressure distributions between two types of sockets in a bulbous stump. prosthet orthot int. 2016; 40(4):50916. doi: 10.1177/0309364614564022 18.meulenbelt he, geertzen jh, jonkman mf, dijkstra pu. determinants of skin problems of the stump in lower-limb amputees. arch phys med rehabil. 2009; 90(1): 74-81. doi: 10.1016/j.apmr.2008.07.015 19.schaffalitzky e, gallagher p, maclachlan m, ryall n. understanding the benefits of prosthetic prescription: exploring the experiences of practitioners and lower limb prosthetic users. disabil rehabil. 2011; 33(15-16):1314-23. doi: 10.3109/ 09638288. 2010.529234 20.jordan rw, marks a, higman d. the cost of major lower limb amputation: a 12-year experience. prosthet orthot int. 2012; 36(4):430-4. doi: 10.1177/0309364612441489 21.boone da. the economic value of mobility with a prosthesis. j prosthet orthot. 2019; 31(1s). doi: 10.1097/jpo. 0000000000000231 22.fish d. the development of coverage policy for lower extremity prosthetics: the influence of the payer on prosthetic prescription. j prosthet orthot. 2006; 18(6):125-129. doi:10.1097/00008526-200601001-00017 23.papaioannou g, mitrogiannis c, nianios g, fiedler g. assessment of amputee socket–stump–residual bone kinematics during strenuous activities using dynamic roentgen stereogrammetric analysis. j biomech. 2010; 43(5):871-878. doi: 10.1016/j.jbiomech.2009.11.013 24.zheng yp, mak af, leung ak. state-of-the-art methods for geometric and biomechanical assessments of residual limbs: a review. j rehabil res dev. 2001; 38(5):487-504. 25.gholizadeh h, osman na, eshraghi a, ali s. transfemoral prosthesis suspension systems: a systematic review of the literature. am j phys med rehabil. 2014; 93(9): 809-23. doi: 10.1097/phm.0000000000000094 26.gerzina c, potter e, haleem am, dabash s. the future of the amputees with osseointegration: a systematic review of literature. j clin orthop trauma. 2020; 11(suppl 1): s142-s148. doi: 10.1016/j.jcot.2019.05.025 27.potter bk. from bench to bedside: we can (still) do bettermoving towards more thoughtful, "constructive" amputations. clin orthop relat res. 2019; 477(8):1793-1795. doi: 10.1097/ corr.0000000000000872 28.overmann al, forsberg ja. the state of the art of osseointegration for limb prosthesis. biomed eng lett. 2019; doi: 10.1007/s13534-019-00133-9 29.frossard l, hagberg k, häggström e, gow dl, brånemark r, pearcy m. functional outcome of transfemoral amputees fitted with an osseointegrated fixation: temporal gait characteristics. j prosthet orthot. 2010; 22(1): 11-20. doi: 10.1097/jpo. 0b013e3181ccc53d 30.frossard l, ferrada l, berg d. survey data on the quality of life of consumers fitted with osseointegrated fixation and boneanchored limb prostheses provided by government organization. data in brief. 2019; 26:104536. doi: 10.1016/j.dib.2019.104536 31.helgason b, pálsson h, rúnarsson tp, frossard l, viceconti m. risk of failure during gait for direct skeletal attachment of a femoral prosthesis: a finite element study. med eng phys. 2009; 31(5):595-600. doi: 10.1016/j.medengphy.2008.11.015 32.frossard l, haggstrom e, hagberg k, branemark r. load applied on a bone-anchored transfemoral prosthesis: characterisation of prosthetic components – a pilot study. j rehabil res dev. 2013; 50(5): 619–634. doi: 10.1682/jrrd.2012.04.0062 https://doi.org/10.33137/cpoj.v4i2.36364 13 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e 33.frossard l, leech b, pitkin m. automated characterization of anthropomorphicity of prosthetic feet fitted to bone-anchored transtibial prosthesis. ieee trans biomed eng. 2019; 66(12): 34023410. doi: 10.1109/tbme.2019.2904713 34.frossard l, leech b, pitkin m. loading applied on osseointegrated implant by transtibial bone-anchored prostheses during daily activities: preliminary characterization of prosthetic feet. j prosthet orthot. 2020; 32(4):258-271. doi: 10.1097/ jpo.0000000000000280 35.highsmith mj, kahle jt, lewandowski a, klenow td, orriola jj, miro rm, et al. economic evaluations of interventions for transtibial amputees: a scoping review of comparative studies. technol innov. 2016;18(2-3):85-98. doi:10.21300/18.2-3.2016.85. 36.tai bb, bae yh,le qa. a systematic review of health economic evaluation studies using the patient's perspective. value health. 2016; 19(6): 903-908. doi: 10.1016/j.jval.2016.05.010 37.ijzerman mj, steuten lm. early assessment of medical technologies to inform product development and market access: a review of methods and applications. appl health econ health policy. 2011; 9(5):331-47. doi: 10.2165/11593380-00000000000000 38.kannenberg a, seidinger s. health economics: the perspective of a prosthetic manufacturer. j prosthet orthot. 2019; 31(1s). doi:10.1097/jpo.0000000000000234 39.eshraghi a, osman na, gholizadeh h, karimi m, ali s. pistoning assessment in lower limb prosthetic sockets. prosthet orthot int. 2012; 36(1):15-24. doi: 10.1177/0309364611431625 40.frossard la, tranberg r, haggstrom e, pearcy m, brånemark r. load on osseointegrated fixation of a transfemoral amputee during a fall: loading, descent, impact and recovery analysis. prosthet orthot int. 2010; 34(1): 85-97. doi: 10.3109/ 03093640903585024 41.osseointegrated prosthetic implants for people with lower-limb amputation: a health technology assessment [internet]. ont health technol assess ser. 2019;[cited 2021, june 9]. available from: http://www.hqontario.ca/evidence-to-improve-care/journalontariohealth-technology-assessment-series 42.martin r. rapid review of osseointegration/ direct skeletal fixation-a report for nhs england [internet]. bazian ltd: uk, 2016; [cited 2021, june 9]. available from: https://www.ispo.org.uk/resources/bazian-report.pdf 43.amsan an, nasution ak, riau p, ramlee mh. a short review on the cost, design, materials and challenges of the prosthetics leg development and usage. international conference of celscitech 2019-science and technology track (iccelst-st 2019) 2019; 5964. doi:10.2991/iccelst-st-19.2019.12 44.kaulback k, jones a. osseointegrated prosthetic implants for lower limb amputation: a review of clinical effectiveness, costeffectiveness and guidelines [internet]. ottawa (on): canadian agency for drugs and technologies in health; 2017; [cited 2021, june 9]. available from: https://pubmed.ncbi.nlm.nih.gov/28825780/ 45.frossard l, ferrada l, berg d. survey on the quality of life of consumers fitted with osseointegrated fixation and bone-anchored limb prostheses provided by government organization. 2019; mendeley data. doi: 10.17632/bkbxxmrhfh.1 46.frossard l, ferrada l, quincey t, burkett b, berg d. development of a government continuous quality improvement procedure for assessing the provision of bone anchored limb prosthesis: a process re-design descriptive study. can prosthet orthot j. 2018; 1(2). doi: 10.33137/cpoj.v1i2.31326 47.frossard l, merlo g, quincey t, burkett b, berg d. development of a procedure for the government provision of boneanchored prosthesis using osseointegration in australia. pharmacoeconomics. 2017; 1(4): 301-314. doi: 10.1007/s41669017-0032-5 48.stevens pm, highsmith mj, sutton b. measuring value in the provision of lower-limb prostheses. j prosthet orthot. 2019; 31(1s). doi: 10.1097/jpo.0000000000000232 49.frossard l, debra b. australian innovations of health services and economic evaluation of bone-anchored prosthesis using osseointegration, in australian orthotic prosthetic association (aopa) congress. 2017; melbourne, australia. 50.frossard l, ferrada l, quincey t, berg d. cost-effectiveness of transtibial bone-anchored 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https://doi.org/10.33137/cpoj.v4i2.36364 http://www.hqontario.ca/evidence-to-improve-care/journalontario-health-technology-assessment-series http://www.hqontario.ca/evidence-to-improve-care/journalontario-health-technology-assessment-series https://www.ispo.org.uk/resources/bazian-report.pdf https://pubmed.ncbi.nlm.nih.gov/28825780/ 14 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e 61.frossard l, debra b. australian innovations of health services and economic evaluation of bone-anchored prosthesis using osseointegration, in australian orthotic prosthetic association (aopa) congress. 2017; melbourne, australia. 62.haggstrom ee, hansson e, hagberg k. comparison of prosthetic costs and service between osseointegrated and conventional suspended transfemoral prostheses. prosthet orthot int. 2013; 37(2):152-60. doi: 10.1177/0309364612454160 63.hansson e, hagberg k, cawson m, brodtkorb th. patients with unilateral transfemoral amputation treated with a percutaneous osseointegrated prosthesis: a cost-effectiveness analysis. bone joint j. 2018; 100-b(4):527-534. doi: 10.1302/0301-620x. 100b4.bjj-2017-0968.r1 64.brodtkorb th, henriksson m, johannesen-munk k, thidell f. cost-effectiveness of c-leg compared with non-microprocessorcontrolled knees: a modeling approach. arch phys med rehabil. 2008; 89(1): 24-30. doi: 10.1016/j.apmr.2007.07.049 65.gerzeli s, torbica a, fattore g. cost utility analysis of knee prosthesis with complete microprocessor control (c-leg) compared with mechanical technology in trans-femoral amputees. eur j health econ. 2009; 10(1): 47-55. doi: 10.1007/s10198-008-01029 66.cutti ag, lettieri e, del maestro m, radaelli g, luchetti m, verni g, et al., stratified cost-utility analysis of c-leg versus mechanical knees: findings from an italian sample of transfemoral amputees. prosthet orthot int. 2017; 41(3):227-236. doi: 10.1177/ 0309364616637955 67.chen c, hanson m, chaturvedi r, mattke s, hillestad r, liu hh. economic benefits of microprocessor controlled prosthetic knees: a modeling study. j prosthet orthot. 2019; 31(1s) 68.normann e, olsson a, brodtkorb th. modular socket system versus traditionally laminated socket: a cost analysis. prosthet orthot int. 2011; 35(1): 76-80. doi: 10.1177/0309364610392812 69.cutti ag, lettieri e, verni g. health technology assessment as theoretical framework to assess lower-limb prosthetics—issues and opportunities from an international perspective. j prosthet orthot. 2019; 31(1s):55-73. doi: 10.1097/jpo.0000000000000235 70.gordon r, magee c, frazer a, evans c, mccosker k. an interim prosthesis program for lower limb amputees: comparison of public and private models of service. prosthet orthot int. 2010; 34(2): 17583. doi: 10.3109/03093640903510980 71.datta d, harris i, heller b, howitt j, martin r. gait, cost and time implications for changing from ptb to icex sockets. prosthet orthot int. 2004; 28(2):115-20. doi: 10.1080/03093640408726696 72.highsmith mj, kahle jt, wernke mm, carey sl, miro rm, lura dj, et al. effects of the genium knee system on functional level, stair ambulation, perceptive and economic outcomes in transfemoral amputees. technol innov. 2016; 18(2-3): 139-150. doi: 10.21300/18.2-3.2016.139 73.seelen ha, hemmen b, schmeets aj, ament aj, evers sm. costs and consequences of a prosthesis with an electronically stance and swing phase controlled knee joint. technol disabil. 2009; 21(1,2): 25-34. doi: 10.3233/tad-2009-0269 74.selles rw, janssens pj, jongenengel cd, bussmann jb. a randomized controlled trial comparing functional outcome and cost efficiency of a total surface-bearing socket versus a conventional patellar tendon-bearing socket in transtibial amputees. arch phys med rehabil. 2005; 86(1):154-61; quiz 180. doi: 10.1016/j.apmr. 2004.03.036 75.husereau d, drummond m, petrou s, carswell c, moher d, greenberg d, et al. consolidated health economic evaluation reporting standards (cheers)--explanation and elaboration: a report of the ispor health economic evaluation publication guidelines good reporting practices task force. value health. 2013; 16(2): 231-50. doi: 10.1016/j.jval.2013.02.002 76.van mastrigt ga, hiligsmann m, arts jj, broos ph, kleijnen j, evers sm, et al. how to prepare a systematic review of economic evaluations for informing evidence-based healthcare decisions: a five-step approach (part 1/3). expert rev pharmacoecon outcomes res. 2016; 16(6): 689-704. doi: 10.1080/ 14737167.2016.1246960 77.gerkens s, crott r, cleemput i, thissen jp, closon mc, horsmans y, et al. comparison of three instruments assessing the quality of economic evaluations: a practical exercise on economic evaluations of the surgical treatment of obesity. int j 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uncertainty in the economic evaluation of health care technologies: the role of sensitivity analysis. health econ. 1994; 3(2): 95-104. doi: 10.1002/hec. 4730030206. 83.basu, a. and m.l. maciejewski, choosing a time horizon in cost and cost-effectiveness analyses. jama, 2019. 321(11): p. 1096. doi: 10.1001/jama.2019.1153. 84.wijnen bf, van mastrigt ga, redekop wk, majoie hj, de kinderen rj, evers sm. how to prepare a systematic review of economic evaluations for informing evidence-based healthcare decisions: data extraction, risk of bias, and transferability (part 3/3). expert rev pharmacoecon outcomes res. 2016; 16(6): p. 723732. doi: 10.1080/14737167.2016.1246961 85.thielen fw, van mastrigt ga, burgers lt, bramer wm, majoie hj, evers sm, et al. how to prepare a systematic review of economic evaluations for clinical practice guidelines: database selection and search strategy development (part 2/3). expert rev pharmacoecon outcomes res, 2016. 16(6): p. 705-721. doi: 10.1080/14737167.2016.1246962 86.frossard l, stevenson n, sullivan j, uden m, pearcy m. categorization of activities of daily living of lower limb amputees during short-term use of a portable kinetic recording system: a https://doi.org/10.33137/cpoj.v4i2.36364 15 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e preliminary study. j prosthet orthot. 2011; 23(1): 2-11. doi: 10.1097/jpo.0b013e318207914c author scientific biography dr laurent frossard is a bionic limbs scientist who is passionate about developing groundbreaking prosthetic solutions to improve the lives of individuals suffering from limb loss. he is internationally recognized as a researcher and an independent expert for his unique expertise in bionic limbs. he approaches bionic solutions from a holistic perspective, by integrating the prosthetic biomechanics, clinical benefits, service delivery, and health economics. dr frossard has over 25 years of experience, both in academia and in private industries in australia, canada, and europe. he has collaborated with over 100 organizations worldwide. he is currently a professor of bionics at the griffith university, the director and chief scientist officer at yourresearchproject pty ltd, and adjunct professor at the queensland university of technology and the university of sunshine coast in australia. https://doi.org/10.33137/cpoj.v4i2.36364 16 frossard l. trends and opportunities in health economic evaluations of prosthetic care innovations. canadian prosthetics & orthotics journal. 2021; volume 4, issue 2, no.9. https://doi.org/10.33137/cpoj.v4i2.36364 issn: 2561-987x health economic evaluations of prosthetic care innovations frossard l, 2021 cpoj special s p e c ia l i s s u e appendix 1: definition of key terms basic framework of preliminary costutility analysis generic canvas of preliminary cost-utility analysis including set constructs specific to prosthetic care innovations cost-effectiveness analysis form of economic analysis that compares the relative costs expressed in monetary value and particular functional outcome of a treatment (e.g., walking speed) cost-utility analysis form of economic analysis that compares the relative costs expressed in monetary value and health effects of various interventions converted into utilities expressed quality-adjusted life-year health economic evaluation comparative assessment of costs and outcomes of alternative health care technologies or health strategies providing incremental cost-outcome ratio, the relation of the estimated additional costs and the estimated additional outcome saved or lost by using an alternative health care technology health technology assessment systematic evaluation of the properties and effects of a health technology, addressing the direct and intended effects of this technology, as well as its indirect and unintended consequences, and aimed mainly at informing decision making regarding health technologies modelling cost-utility analysis form of analysis projecting of cost-utility based on decision-analytic models involving bayesian or markov models generally using plausible information extracted from primary studies primary cost-utility analysis form of analysis relying on actual costs extracted from financial records expressed in monetary units or actual utilities measured by quality of life surveys converted into quality-adjusted life-year promoters of prosthetic care interventions groups developing and encouraging prosthetic care interventions including individuals suffering from limb loss (users’ perspectives), providers of prosthetic solutions (manufacturers’ perspective), rehabilitation and prosthetic specialists (clinicians’ perspective) and administrators of healthcare organisations (taxpayers perspective) prosthetic care innovation new intervention susceptible to alleviate clinical shortcomings and financial burden of current prosthetic fitting options schedule of allowable expenses matrix of costs (monetary units of talk) at the intersection of rows corresponding to lists of tasks (type of expenses) and columns corresponding to onsets of tasks (time of expenses) uncertainty and sensibility of health economic evaluations the size of the errors around the estimates of costs and utilities due to data sources (e.g., sample size) and/or to the process of evaluation (markov modelling), https://doi.org/10.33137/cpoj.v4i2.36364 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 1 2024 research article mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i1.43896 1 mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 research article feasibility of a yoga intervention in an inpatient limb loss rehabilitation program mayo a.l1,2 *, cheung b1, li j1, jean s3, vijayakumar a1, hitzig s.l1,4, simpson r2,5 1. st. john’s rehab research program, sunnybrook research institute, sunnybrook health sciences centre, toronto, canada. 2. temerty faculty of medicine, university of toronto, toronto, canada. 3. department of medicine, university of montreal, montreal, canada. 4. department of occupational science and occupational therapy, temerty faculty of medicine, university of toronto, toronto, canada. 5. toronto rehabilitation institute, university health network, toronto, canada. introduction lower extremity amputation (lea) is associated with poor balance, decreased physical strength, and decreased mobility, as well as high rates of depression, and social isolation.1-6 similar to global trends,7,8 the leading cause of lea in canada are dysvascular in nature due to complications of peripheral arterial disease (pad) and/or diabetes mellitus (dm).9-11 other causes of lea (non-dysvascular) include trauma, cancer or non-diabetes/pad related infection and/or ischemia.12-15 patients with dysvascular lea often have a high number of co-morbidities,16 which requires them to adopt a chronic condition management approach while adapting to life with a new physical disability.17 in particular, residual limb pain and phantom limb pain (plp) are commonly experienced post-amputation,18-20 for both dysvascular and non-dysvascular lea (e.g., trauma, cancer, etc.), and can further reduce physical function and wellbeing.21-23 as a result of reduced mobility and health challenges, individuals with lea have high rates of sedentary lifestyles,24 which can exacerbate their chronic health conditions, such as heart disease, pad and dm; thereby elevating their risk for mortality.25 open access abstract background: limb loss is a life-changing event, which may be associated with limited mobility, pain, and low mood. yoga interventions have been found to be beneficial for improving emotional wellness and pain in other patient populations. the benefits of including yoga in limb loss rehabilitation have not been well studied. objective: the purpose of this study was to determine if an adaptive yoga program would be suitable for individuals with newly acquired limb loss in a rehabilitation program. methodology: a yoga video was co-designed by rehabilitation clinicians and a limb loss patient partner certified in yoga instruction. surveys were used to collect patients’ socio-demographics and previous yoga experience. participants completed a therapist guided group yoga video session, and then given online access to practice independently. post-yoga participation surveys and qualitative interviews were conducted with patients to determine acceptance and feasibility of the yoga intervention. findings: twenty-four participants with lower limb amputation(s) were approached to participate. the majority of participants (63%) had dysvascular-related amputations. nineteen out of 24 recruited patients (79%) completed the yoga video session and the pre-yoga survey. sixteen out of 19 participants completed the post-yoga survey, and eight also completed a qualitative interview. five had previously undertaken yoga but rated themselves as novices. all participants felt that yoga was beneficial, easy to complete, and should be included in rehabilitation. participants found yoga to be relaxing and some noted reduction in pain. most preferred to do yoga in a group. five out of eight patients (63%) interviewed continued to do the yoga video independently in hospital and post-discharge. challenges with the yoga intervention included lack of a quiet yoga space, and dedicated time given other appointments/priorities. conclusion: yoga was widely accepted by the inpatient limb loss population. yoga may complement traditional limb loss rehabilitation by providing patients a relaxing experience; however, further research is needed. article info received: august 26, 2024 accepted: october 7, 2024 published: october 24, 2024 citation mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1 .43896 keywords yoga, qualitative, survey, pain, amputation, rehabilitation, lower extremity amputation * corresponding author: dr. amanda l. mayo, affiliation: st. john’s rehab research program, sunnybrook research institute, toronto, canada. e-mail: amanda.mayo@sunnybrook.ca orcid id: https://orcid.org/0000-0001-7061-2529 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 1, article no.6. 2024 https://doi.org/10.33137/cpoj.v7i1.43896 https://doi.org/10.33137/cpoj.v7i1.43896 https://doi.org/10.33137/cpoj.v7i1.43896 mailto:amanda.mayo@sunnybrook.ca https://orcid.org/0000-0001-7061-2529 https://jps.library.utoronto.ca/index.php/cpoj/index 2 mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 canadian prosthetics & orthotics journal issn: 2561-987x feasibility of a yoga intervention in an inpatient limb loss rehabilitation program mayo et al., 2024 in canada, limb loss rehabilitation programs traditionally include physiotherapy, occupational therapy, and/or prosthetic training.9 inpatient rehabilitation programs are typically accessed by patients with newly acquired limb loss and/or for first time training with a prosthesis.9,17 it is known that patients with limb loss have high rates of adjustment disorder, depression and/or anxiety in the first months following amputation when they are accessing rehabilitation services,4 and that patients often feel that their mental health needs are not prioritized.26 consequently, there is a need for wellness programs in canadian limb loss rehabilitation programs, which are currently lacking.4,26 yoga has been found to be a promising intervention to improve health and wellness that can be adapted for people with physical disabilities. it has been found to improve mood and pain in a variety of patient populations, such as those with fibromyalgia, multiple sclerosis, and spinal cord injury.27-30 yoga is an ancient practice with a focus on physical, mental, emotional, and spiritual health.31 developed in india, yoga has eight domains or “limbs,” which consist of yama (universal ethics), niyama (individual ethics), asana (physical postures), pranayama (breath control), pratyahara (control of the senses), dharana (concentration), dhyana (meditation), and samadhi (bliss).31 most healthcare yoga interventions have focussed on use of physical postures,31 breath control,32 and/or meditation.33 qualitative reports of different patient groups who have participated in yoga often share positive reactions to the intervention,34-36 and that it had some advantages to other forms of exercise (e.g., less fatiguing, less discomfort).33 adaptive yoga programs for individuals with limb loss exist37 but its benefits have not been well studied, nor has yoga been incorporated regularly into limb loss rehabilitation programs. given the high rates of sedentary lifestyles, pain, and psychological distress post-limb loss, yoga may be a promising intervention that can be introduced early in the rehabilitative process. as well, people with limb loss are known to have difficulty accessing community services, such as exercise programs due to lack of transportation, financial costs, and/or lack of suitable facilities.38,39 hence, adaptive yoga may offer patients with an exercise option they can pursue if other factors (i.e., income, transportation) create barriers to leisure-time physical activity. the original purpose of this study was to determine if a yoga for limb loss in-person program could be incorporated into a lea inpatient rehabilitation program. however, due to the covid-19 pandemic and episodes of restricted group exercise, the focus of the study was shifted to determine the feasibility and acceptability of using an online adaptive yoga video intervention among patients with lea. we hypothesised that individuals with lea would be interested in participating in an online yoga video program, and that it would be an acceptable addition to traditional limb loss rehabilitation programs. methodology a mixed methods study design was used to test the feasibility and acceptability of an adaptive online yoga intervention for inpatient rehabilitation patients with newly acquired limb loss. the main research question was to determine if an adaptive virtually-delivered yoga program for limb loss is feasible to implement in a rehabilitation inpatient setting, and to determine if the program would be well-received by participants. post-yoga likert scale intervention surveys were used to determine participant acceptance of, and experiences with the adapted yoga program. semi-structured interviews were conducted to explore participant thoughts on perceived benefits, what is needed to improve the program, and to gather other suggestions for making the yoga intervention more accessible to the wider limb loss community. participants the inclusion criteria for the study were english-speaking adult patients with lea of any etiology (dysvascular, trauma, cancer, etc.) admitted to the inpatient amputee rehabilitation unit at sunnybrook st. john’s rehab hospital in toronto, on, canada. to take part, participants were required to be medically cleared physically and cognitively to be able to participate in the adaptive online yoga intervention by the unit’s physical medicine and rehabilitation physician (physiatrist). in addition, participants needed to have internet access in their homes, a device that would enable them to access the adapted online yoga intervention, and were able to undergo the study assessments. this study received ethics approval by the research ethics board of the sunnybrook health sciences centre (reb #5227). adaptive yoga intervention the yoga intervention was designed by our team of physiatrists with expertise and training in yoga and lea (mayo a.l, simpson r), as well as by a physiotherapist (cheung b) and an occupational therapist (li j) with lea expertise. the basis for the program was established by reviewing marsha danzig’s yoga4amputee (https://www.yogaforamputees.com) instructor training materials,37 and by consulting with a study partner, who is a person with lea (hauer, l) and a certified yoga instructor. to accommodate individuals with new lea who may not yet have a prosthesis, a chair-based yoga program was created. the created video was 45 minutes, and the instructor for the video yoga session was our patient partner with lea. the yoga video was made available online on a youtube channel, which was only accessible to those who were provided a link for viewing. the physiotherapist (cheung b) and occupational therapist (li j) on our study team completed online training provided by yoga for amputees (https://www.yogaforamputees.com/classestraining) to learn the yoga exercises. these therapists https://doi.org/10.33137/cpoj.v7i1.43896 https://www.yogaforamputees.com/ https://www.yogaforamputees.com/classes-training https://www.yogaforamputees.com/classes-training 3 mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 canadian prosthetics & orthotics journal issn: 2561-987x feasibility of a yoga intervention in an inpatient limb loss rehabilitation program mayo et al., 2024 provided orientation to study participants, and supervised participants who took part in a group video session. participants completed the yoga video session in groups of 2-4 during their inpatient amputee rehabilitation admission. once the group video session was completed participants were given the youtube link so they could continue to participate in yoga independently. procedure admitted patients with lea to st. john’s rehab hospital who met the inclusion criteria were informed about the study by a member of their rehab care team (therapist or physician). if the participants wanted to learn more, the study coordinator followed-up and obtained informed consent for those participants who agreed to participate. twenty-four participants were recruited into this study between august 2022 and june 2023. a study flow-chart is illustrated in figure1. prior to completing the yoga session, participants completed a likert-scale survey comprised of 10 questions that collected data on socio-demographics, previous yoga experiences, and digital literacy (figure 2). to understand more in-depth the individual experiences of participants with the yoga intervention, participants were requested to take part in a post-yoga survey, and in a semi-structured interview. the interview incorporated the following five questions: 1: why were they interested in participating in the program? 2: what concerns, if any, did they have about participating in an online yoga intervention? 3: what aspects they enjoyed or did not like? 4: suggestions for improvement? 5: any other insights about promoting yoga to the limb loss community? these interviews were conducted over phone or by zoom and ranged from 10-30 minutes. interviews were then transcribed verbatim for narrative analysis. analysis descriptive statistics and frequencies were used to analyze the data. to understand acceptability and feasibility of the adaptive online yoga intervention, the rate of yoga participation was calculated, which included the ability of participants to complete the video in the group session at the inpatient rehabilitation setting, and independent use of the yoga video post group session was calculated. for the interview data, a narrative research approach40-42 was taken to highlight participant experience and feedback regarding their attitudes about yoga, its’ perceived benefits, and recommendations for improvement. study team members (vijayakumar a, mayo a.l) coded responses and identified themes from the interviews. given that the interviews were relatively short (10 – 30 minutes), a descriptive narrative summative approach was determined to be sufficient to obtain critical insights about the yoga intervention. to help illustrate the main findings of the interview data, illustrative quotes with key participant descriptors are provided. figure1: study protocol flow chart. results of the twenty-four participants who were deemed eligible and approached to participate in the study, 19 agreed to participate in the yoga intervention (79% enrollment rate). all of the participants were those with a newly acquired lea within the past three months, with one patient who was admitted for a second amputation with history of a contralateral amputation the year prior. seven (37%) had a traumatic etiology, and the rest (63%) had a dysvascular etiology. four participants were female (21%) and 15 (79%) were male. participants’ ages ranged from 25 to 85 years old, with an average age was 58.9 years (sd=18.9). only four of the participants (21%) had participated in yoga before the study, and all these participants rated themselves as novice level yoga participants. in terms of digital literacy, the majority self-rated themselves as having good levels of literacy (68%), with only two rating themselves as being very good or excellent (11%), and the rest stating it was fair or poor (21%). the complete demographics of the participants, self-rated technology skills and yoga experience are outlined in table 1. of the 19 participants that participated in the adaptive yoga intervention, 16 (84%) completed the post-yoga survey (appendix a), while 3 were unable to complete it due to being discharged from inpatient rehabilitation or declined to complete. post-yoga survey results are illustrated in figure 2. the results of the post-yoga survey report that the majority participants found yoga to be a positive calming experience. all but one yoga participant (95%) were comfortable doing yoga and only 2 of the 16 (13%) respondents stated they did not wish to do yoga again. all participants found the video easy to complete. participants recruited into the study group yoga video session post-yoga survey +/interview pre-yoga survey (if consent obtained) https://doi.org/10.33137/cpoj.v7i1.43896 4 mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 canadian prosthetics & orthotics journal issn: 2561-987x feasibility of a yoga intervention in an inpatient limb loss rehabilitation program mayo et al., 2024 eight (42%) yoga participants completed post-yoga semistructured interviews in addition to the post-yoga survey via phone or zoom. key themes that were identified from the transcripts were openness to yoga, calming/relaxing benefits, peer support, and need for a dedicated yoga space and time in rehabilitation. expectations and openness to yoga most of the participants did not have any pre-set expectations of taking part in yoga, and indicated they joined to just learn more about it and how it may help them to stay more active. for instance, one person stated: “i didn’t have any expectations or hopes, to be honest, i was just trying it out.” (male, 25 years, left bka), with others commenting: “i just want to experience what yoga is.” (male, 57 years, right aka) “so, i was actually very open to it. i feel it helped that i had a good relationship with the roommate at the time i had, so it was easier to get involved, so it made it even more enjoyable and comfortable to go to, because you had a familiar companion and a friend.” (male, 39 years, left bka). once tried, however, participants stated they would like more yoga sessions to participate in during rehabilitation. therapeutic benefits in terms of the perceived therapeutic benefits, all eight participants found the yoga session calming. one patient who had experienced recent trauma found the session to be relaxing where he stated: “honestly, i liked the way it went. just in a room, quiet, i was at peace.” (male, 25 years, left bka). as well, participants felt it complimented their formal rehabilitation by offering gentler exercises, stretching, and teaching breathing techniques. one person commented that compared to their physiotherapy sessions, yoga was not painful at all. other specific aspects that participant enjoyed were the stretching: “physically, i love the stretches. i love the way i feel limber, but comfortable. because when you’re going through this process, you’re using other muscles to compensate for your balance, just your motion, how you do day-to-day stuff. you’re using different parts of your back muscles that you don’t use daily, so you get tight and crampy. so, the stretching from the yoga was great for that.” (male, 74 years, aka and bka) overall, all the participants enjoyed the yoga video, felt safe completing the video, and were happy they participated in the program. group in setting with peers participants appreciated having a peer limb loss instructor for the video since they felt it modeled ways on how they could move with their amputation. in general, the ability to connect with peers was highly valued, with six of the eight (75%) participants rating they would benefit the most from yoga doing it in a group setting. one person shared: “socially. yes, i knew the guys in there. maybe i met a couple guys in there that weren't there before. so, yes, there are benefits of that” (female, 74 years, left bka). overall, it provided a number of social opportunities to patients, and table 1: demographics of the study population. age sex level of education etiology level of amputation technology skills yoga experience yoga level 59 male college trauma bka* good no n/a 25 male some college trauma bka good no n/a 46 female high school trauma aka** good no n/a 68 male college dysvascular bka very good no n/a 39 male some college trauma bka good yes novice 57 female high school trauma aka fair yes novice 68 female some high school dysvascular aka poor no n/a 31 male high school dysvascular bka good no n/a 81 male some high school dysvascular aka fair no n/a 85 male high school dysvascular aka good no n/a 69 male college dysvascular bka fair no n/a 28 male high school trauma aka good yes novice 58 male some high school dysvascular bka good no n/a 74 male university trauma aka good yes novice 50 male high school dysvascular aka good no n/a 74 male high school dysvascular bka good no n/a 83 male high school dysvascular bka good no n/a 48 male college dysvascular bka excellent yes novice 76 female university dysvascular aka/bka good no n/a *below-the-knee amputation (bka) ** above-the-knee amputation (aka) https://doi.org/10.33137/cpoj.v7i1.43896 5 mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 canadian prosthetics & orthotics journal issn: 2561-987x feasibility of a yoga intervention in an inpatient limb loss rehabilitation program mayo et al., 2024 highly beneficial for receiving peer support. importantly, one participant (male, 25 years, bka) commented that his posttraumatic stress disorder (ptsd) made him unable to focus on yoga if he was alone. yoga post-discharge five out of the eight (63%) interviewed participants continued to do the yoga video after the group session while still in inpatient rehabilitation and at home. participants completing the video independently were able to access the video without issues. two of the home participants felt yoga was better while admitted to rehabilitation because there were more distractions at home, and no one to supervise them or do yoga with at home. “that's the difficult part because now you've changed environments. unless people really find it beneficial to them and necessary, they're not going to follow. perfect example, right here. and that's the way it will go unless they have had enough sessions that they see how the real long-term benefit of this. one, two or three sessions.” (female, 74 years, right aka). hence, there were mixed findings regarding participants’ willingness to continue with yoga once discharged home, and that some participants reported they may be more inclined to participate in yoga more independently if they were reminded or coached to do so. feedback and recommendations many participants stated the chosen yoga room (unit patient education room) was not ideal for the intervention. one person commented: “like i said, probably a proper room, to put the people on a mindset, like rest. like for the people feel more rest and focus on the class.” (male, 28 years, right aka). as well, all eight interviewed participants’ desired yoga to be a scheduled session in regular rehabilitation programming. many participants wanted to do scheduled yoga at least once a week. “two times a week was pretty cool. it wasn’t a big group, so i think it worked for that. i think as a group gets bigger, you can have an a group or b group, like a morning group, afternoon group. i don’t know, something like that.” (male, 39 years, left bka). other suggestions by participants were to have pamphlets or information packages to give to patients before they enroll, and that a mix of in-person and online sessions would be preferred, with one person commenting: “well, i'm still old school, but i still like the in person and it's more personal. even if you got six or eight people that are with you, it's more personal if you got an instructor there.” (female, 74 years, right aka). as well, issues of digital literacy and access were raised as potential barriers. discussion the purpose of the present study was to explore the feasibility and acceptability of an adapted online yoga video program. based on our findings, it appears there was a high degree of interest in exploring yoga given that 79% of approached participants wanted to learn more. as well, despite our participants having little or no experience with yoga, they were enthusiastic about participating in the intervention based on our survey and qualitative data; with many of them reporting to find it beneficial for their wellbeing. this finding is similar to other studies exploring yoga in other patient populations. for instance, one study that piloted an adapted yoga program for spinal cord injury patients had qualitative reports by patients stating they had high satisfaction with the program, that it helped them with figure 2: post-yoga survey results (n =16 participants). i felt calm & peaceful while doing yoga the yoga practice was easy to complete i felt pain during the yoga practice yoga improved the way i feel i felt anxious during the yoga practice i would recommend yoga to other patients i would like to do yoga again i felt safe while doing yoga i felt overwhelmed by including yoga practice on top of my regular therapy i felt comfortable while doing yoga strongly disagree / disagree neutral agree / strongly agree https://doi.org/10.33137/cpoj.v7i1.43896 6 mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 canadian prosthetics & orthotics journal issn: 2561-987x feasibility of a yoga intervention in an inpatient limb loss rehabilitation program mayo et al., 2024 experiences of the self and relaxation, and helped with pain relief.28 similar to other studies on other populations where patients noting yoga had advantages over other forms of exercise,33 our participants’ commented that participating in yoga was less strenuous than other activities typical of inpatient rehabilitation (e.g., physiotherapy) and it may be that relaxation is a modality underutilized in current rehab programming for leas. of the patients interviewed, 5/8 (63%) continued the yoga intervention practice beyond the study intervention session. frequent practice of yoga has been associated with physical, emotional, and mental health benefits.43 studies exploring the impact of yoga often do so over a series of sessions. for instance, a recent randomized controlled trial that tested the benefits of yoga in a traumatic lea population found that those (n=24) who took part in the 18 week yoga intervention (daily 30 minute yoga session; including unsupervised sessions) yielded significant improvements in overall quality of life, as well as in physical, psychological and environmental domains of wellbeing compared to a group receiving usual prosthetic and rehabilitation treatments without yoga (n=23). these effects were detected as early as six weeks.44 our yoga intervention showed promise in being a suitable adjunct activity to inpatient rehabilitation, but our participants indicated they would like more frequent yoga sessions. similar findings for more frequent sessions have been noted in other yoga studies.36,43 integration of yoga practice into regular rehabilitation programming would appear to benefit participants but a suitable quiet space, yoga content, and scheduling of yoga around other rehab activities would be needed. data on the benefits of yoga for dysvascular lea patients, however, is needed, and the nuances and appropriateness of yoga for trauma populations requires further attention. for instance, one of our participants with a traumatic etiology noted that doing yoga on his own triggered his ptsd. ptsd is a common issue following major trauma, and is associated with a variety of symptoms, including intrusions (e.g., unwanted flashbacks), engaging in avoidant behaviors to avoid trauma reminders, negative alterations in mood and cognition, and hypervigilance.45 there is evidence that mindfulness-based approaches (encouraging of fostering nonjudgment and acceptance of one’s thoughts and emotions as they occur in the present moment),46 which yoga interventions sometimes integrate through the meditation component, are not well-suited for trauma populations if not properly introduced or monitored. for some persons with ptsd, mindfulness-based approaches may lead to increased distress, especially individuals who are prone to flashbacks, rumination, or are easily triggered by their trauma memories.47 thus, although adapted yoga holds promise for people with lea, like mindfulness-based approaches, it too may need further adaptation to ensure it is ‘trauma sensitive’. not surprisingly, participants were interested in undertaking yoga in a group and appreciated having the online video being led by someone with limb loss. in one qualitative study exploring facilitators and barriers to physical activity, participants (n=33) commented about the importance of social support and being surrounded by peers with a shared mutual experience of the impact of limb loss.38 hence, participating in a group of peers that was led, albeit asynchronously, by a peer was likely a motivating factor for wanting to take part in the intervention. limitations there are several limitations to the present study. first, the original purpose was to do an in-person yoga program at our inpatient setting. unfortunately, our study was set to commence just as the covid-19 pandemic occurred, which required us to delay the start of the program, and then to modify it to minimize the spread of potential infection. this re-adjustment led to the creation of an online video whereby our team was able to introduce the yoga intervention by a yoga trained physiotherapist and occupational therapist, which was then pursued by participants on their own accord. unfortunately, we were only able to create a 45-minute session video, and did not collect data on efficacy of the program. this was not pursued due to our initial desire to create a suitable adapted yoga program that had basis for the limb loss population.37 as well, our emphasis was on feasibility and acceptability, and therefore we focused on those metrics as the starting point for the development of the intervention. our data indicates that an adapted online yoga video was feasible to implement in our inpatient setting, but its’ broader feasibility cannot be determined based on our available data. despite the limitations of the study, it does appear that yoga was deemed acceptable by our participants through the ratings on the survey and by their qualitative reports. future work future work should explore clinical efficacy via a more robust controlled trial for lea populations as well as hybrid or tele-rehabilitation models of delivery. as noted, people with lea fail to participate in sufficient levels of physical activity, which increases their risk for the development of cardiovascular disease, and mortality.24,48,49 there is evidence that tele-rehabilitation approaches can serve to improve yoga adherence and is clinically effective in a variety of rehabilitation patients, which may help to maintain long-term benefits and engagement in physical activity.50-52 studies evaluating yoga-based interventions should consider how to facilitate their uptake while in clinic to ensure safe practices are taught to patients while a telerehabilitation or app-based component may enable patients to continue with yoga once home, which may provide a source of activity to those who face numerous barriers to accessing exercise in their communities. as well, a more https://doi.org/10.33137/cpoj.v7i1.43896 7 mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 canadian prosthetics & orthotics journal issn: 2561-987x feasibility of a yoga intervention in an inpatient limb loss rehabilitation program mayo et al., 2024 robust study should be undertaken to further explore the nuances of the benefits of yoga post-limb loss. conclusion an adaptive yoga video for people with lea was widely accepted by the inpatient population in this study. yoga may complement traditional limb loss rehabilitation, which can enable patients to better adjust early post-amputation while providing a physical activity that is relaxing, and that holds a number of benefits to their wellbeing. the introduction of an adapted yoga intervention while in-hospital that is paired with an online video they can use once discharged from hospital may contribute to patients’ wanting to continue in the engagement in this beneficial mind-body intervention. however, more research is needed to explore implementation considerations and suitability of this intervention for different sub-types of patients, as well as to determine clinical efficacy. acknowledgements we would like to dedicate this manuscript to marsha danzig, who met with the study team and provided guidance in the design of the yoga video for this study. ms. danzig passed away in 2022 and was a person with lived experience who taught adaptive yoga for 20 years. we would also like to thank our patient partner leonard hauer who helped create our yoga intervention. as well, we would like to thank our participants for taking part in the study. declaration of conflicting interests the authors have no declared conflicts of interest. authors contribution • amanda mayo: conceived the study design, obtained the funding for the project, worked to design the yoga intervention with a patient partner with expertise in yoga, oversaw the intervention, analyzed the data, wrote and revised the manuscript. • betty cheung: obtained the funding for the project, worked to design the yoga intervention with a patient partner with expertise in yoga, oversaw the intervention, and analyzed the data. • june li: obtained the funding for the project, worked to design the yoga intervention with a patient partner with expertise in yoga, oversaw the intervention, and analyzed the data. • stephanie jean: worked to design the yoga intervention with a patient partner with expertise in yoga and edited the manuscript. • abirami vijayakumar: coordinated the study, recruited participants, collected data, and analyzed the data. • sander hitzig: conceived the study design, obtained the funding for the project, wrote and revised the manuscript. • robert simpson: conceived the study design, obtained the funding for the project, and worked to design the yoga intervention with a patient partner with expertise in yoga. all authors reviewed the manuscript and approved the final version. sources of support this research study was funded by the sunnybrook health sciences centre practice based research and innovation seed grant. references 1.hitzig sl, dilkas s, payne mw, mackay c, viana r, devlin m, et al. examination of social disconnectedness and perceived social isolation on health and life 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jb. lower extremity amputation. in: statpearls [internet]. treasure island (fl): statpearls publishing. 2024; [cited 2024, oct 14]. available from: https://www.ncbi.nlm.nih.gov/books/nbk546594/ 14.merimsky o, kollender y, bickels j, inbar m, nirkin a, isakov j, et al. amputation of the lower limb as palliative treatment for debilitating musculoskeletal cancer. oncol rep. 1997;4(5):105962. doi: 10.3892/or.4.5.1059 15.oh tk, song ia. incidence and associated risk factors for limb amputation among sepsis survivors in south korea. j anesth. 2021;35(1):51-8. doi: 10.1007/s00540-020-02858-9 16.mayo al, viana r, dilkas s, payne m, devlin m, mackay c, et al. self-reported health condition severity and ambulation status postmajor dysvascular limb loss. prosthet orthot int. 2022;46(3): 239-45. doi: 10.1097/pxr.0000000000000106 17.marquez mg, kowgier m, journeay ws. comorbidity and nonprosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. can prosthet orthot j. 2020;3(1):33916. doi: 10.33137/cpoj.v3i1.33916 18.morgan sj, friedly jl, amtmann d, salem r, hafner bj. crosssectional assessment of factors related to pain intensity and pain interference in lower limb prosthesis users. arch phys med rehabil. 2017;98(1):105-13. doi: 10.1016/j.apmr.2016.09.118 19.mioton lm, dumanian ga, fracol me, apkarian av, valerio il, souza jm, et al. benchmarking residual limb pain and phantom limb pain in amputees through a patient-reported outcomes survey. plast reconstr surg glob open. 2020;8(7):e2977. doi: 10.1097/ gox.0000000000002977 20.limakatso k, bedwell gj, madden vj, parker r. the prevalence and risk factors for phantom limb pain in people with amputations: a systematic review and meta-analysis. plos one. 2020;15(10):e0240431. doi: 10.1371/journal.pone.0240431 21.bosmans jc, suurmeijer tp, hulsink m, van der schans cp, geertzen jh, dijkstra pu. amputation, phantom pain and subjective well-being: a qualitative study. int j rehabil res. 2007;30(1):1-8. doi: 10.1097/mrr.0b013e328012c953 22.van der schans cp, geertzen jh, schoppen t, dijkstra pu. phantom pain and health-related quality of life in lower limb amputees. j pain symptom manage. 2002;24(4):429-36. doi: 10.1016/s0885-3924(02)00511-0 23.kern u, busch v, rockland m, kohl m, birklein f. prevalence and risk factors of phantom limb pain and phantom limb sensations in germany. a nationwide field survey. schmerz. 2009;23(5):47988. doi: 10.1007/s00482-009-0786-5. 24.bussmann jb, grootscholten ea, stam hj. daily physical activity and heart rate response in people with a unilateral transtibial amputation for vascular disease. arch phys med rehabil. 2004;85(2):240-4. doi: 10.1016/s0003-9993(03)00485-4 25.miller mj, blankenship jm, kline pw, melanson el, christiansen cl. patterns of sitting, standing, and stepping after lower limb amputation. phys ther. 2021;101(2). doi: 10.1093/ ptj/ pzaa212 26.mayo al, fung v, hitzig sl, gould s, posa s, summers deluca l, et al. exploring the psychosocial needs of persons with lower extremity amputation and feasibility of internet cognitive behavioural therapy: a qualitative study. disabil rehabil. 2023; 45(24):4025-34. doi: 10.1080/09638288.2022.2144492 27.curtis k, hitzig sl, bechsgaard g, stoliker c, alton c, saunders n, et al. evaluation of a specialized yoga program for persons with a spinal cord injury: a pilot randomized controlled trial. j pain res. 2017;10:999-1017. doi: 10.2147/jpr.s130530 28.curtis k, hitzig sl, leong n, wicks c, ditor d, katz j. evaluation of a modified yoga program for persons with spinal cord injury: a pilot study. therap recreat j. 2015;49(2):97-117. 29.de orleans casagrande p, coimbra dr, de souza lc, andrade a. effects of yoga on depressive symptoms, anxiety, sleep quality, and mood in patients with rheumatic diseases: systematic review and meta-analysis. pm r. 2023;15(7):899-915. doi: 10.1002/pmrj. 12867 30.lysogorskaia e, ivanov t, mendalieva a, ulmasbaeva e, youshko m, brylev l. yoga vs physical therapy in multiple sclerosis: results of randomized controlled trial and the training protocol. ann neurosci. 2023;30(4):242-50. doi: 10.1177/09727531231161994 31.bechsgaard g. the gift of consciousness: patanjali’s yoga sutras (book one). cambridge scholars publishing; 2014. 32.rain m, puri gd, bhalla a, avti p, subramaniam b, kaushal v, et al. effect of breathing intervention in patients with covid and healthcare workers. front public health. 2022;10:945988. doi: 10.3389/fpubh.2022.945988 33.bilc m, pollmann n, buchholz a, lauche r, cramer h. yoga and meditation for menopausal symptoms in breast cancer survivors: a qualitative study exploring participants' experiences. support care cancer. 2024;32(7):413. doi: 10.1007/s00520-024-08603-2 34.weaver ja, richard ak, press d, gupta k, schmid aa, stephens ja. participants with acquired brain injury realized they "could still do things" after a yoga intervention: a qualitative descriptive study. am j occup ther. 2024;78(2). doi: 10.5014/ajot. 2024.050409 35.d'silva a, islam z, marshall da, vallance jk, nasser y, rajagopalan v, et al. experiences of irritable bowel syndrome patients in a virtual yoga program: qualitative findings from a clinical trial. dig dis sci. 2024;69(1):169-79. doi: 10.1007/s10620023-08125-7 36.huang a, anthonypillai j, hapidou eg. experiences of veteran and civilian patients in exploratory yoga sessions for chronic pain: a qualitative study. can j pain. 2023;7(2):2244025. doi: 10.1080/ 24740527.2023.2244025 37.danzig mt. yoga for amputees: the essential guide to finding wholeness after limb loss for yoga students and their teachers. sacred oak publishing; 2018. 38.lee ls, hitzig sl, mayo a, devlin m, dilkas s, mackay c. factors influencing physical activity among individuals with lower limb amputations: a qualitative study. disabil rehabil. 2023;45(9): 1461-70. doi: 10.1080/09638288.2022.2065539 39.miller mj, jones j, anderson cb, christiansen cl. factors influencing participation in physical activity after dysvascular https://doi.org/10.33137/cpoj.v7i1.43896 https://www.ncbi.nlm.nih.gov/books/nbk546594/ 9 mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 canadian prosthetics & orthotics journal issn: 2561-987x feasibility of a yoga intervention in an inpatient limb loss rehabilitation program mayo et al., 2024 amputation: a qualitative meta-synthesis. disabil rehabil. 2019; 41(26):3141-50. doi: 10.1080/09638288.2018.1492031 40.renjith v, yesodharan r, noronha ja, ladd e, george a. qualitative methods in health care research. int j prev med. 2021;12:20. doi: 10.4103/ijpvm.ijpvm_321_19 41.clandinin d. handbook of narrative inquiry: mapping a methodology. thousand oaks, california 2007. available from: https://methods.sagepub.com/book/handbook-of-narrative-inquiry. 42.wang cc, geale sk. the power of story: narrative inquiry as a methodology in nursing research. int j nurs sci. 2015;2(2):195-8. doi:10.1016/j.ijnss.2015.04.014 43.wiese c, keil d, rasmussen as, olesen r. effects of yoga asana practice approach on types of benefits experienced. int j yoga. 2019;12(3):218-25. doi: 10.4103/ijoy.ijoy_81_18 44.mir n, sen ms, mani k, sagar r, arulselvi s, kumar s, et al. impact of yoga intervention in lower limb amputees following trauma in relation to behavior and quality of life: a randomized controlled trial. int j yoga. 2023;16(2):106-15. doi: 10.4103/ijoy. ijoy_156_23 45.american psychiatric association. diagnostic and statistical manual of mental disorders. text revision (dsm-5-tr). https://doi/book/10.1176/appi.books.9780890425787 46.boyd je, lanius ra, mckinnon mc. mindfulness-based treatments for posttraumatic stress disorder: a review of the treatment literature and neurobiological evidence. j psychiatry neurosci. 2018;43(1):7-25. doi: 10.1503/jpn.170021 47.follette vm, briere j, rozelle d, hopper jw, rome di. mindfulness-oriented interventions for trauma: integrating contemplative practices. guilford publications; 2015. 48.desveaux l, goldstein rs, mathur s, hassan a, devlin m, pauley t, et al. physical activity in adults with diabetes following prosthetic rehabilitation. can j diabetes. 2016;40(4):336-41. doi: 10.1016/j.jcjd.2016.02.003 49.pepin me, akers kg, galen ss. physical activity in individuals with lower extremity amputations: a narrative review. phys ther rev. 2018;23(2):77-87. doi: 10.1080/10833196.2017.1412788 50.sarah s, wolfgang m-b, claudia p. effect of telerehabilitation on long-term adherence to yoga as an antihypertensive lifestyle intervention: results of a randomized controlled trial. complement ther clin pract. 2019:35:148-153. doi: 10.1016/j.ctcp.2019.02. 001 51.malik s, dua r, krishnan as, kumar s, kumar s, neyaz o, et al. exercise capacity in patients with chronic obstructive pulmonary disease treated with tele-yoga versus tele-pulmonary rehabilitation: a pilot validation study. cureus. 2022;14(11):e30994. doi: 10.7759/cureus.30994 52.ratcliff cg, bonthala s, torres d, korupolu r. chapter 15 telerehabilitation for integrative health. in: alexander m, editor. telerehabilitation. new delhi: elsevier; 2022; 213-24. https://doi.org/10.33137/cpoj.v7i1.43896 https://methods.sagepub.com/book/handbook-of-narrative-inquiry https://doi/book/10.1176/appi.books.9780890425787 10 mayo a.l, cheung b, li j, jean s, vijayakumar a, hitzig s.l, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.6. https://doi.org/10.33137/cpoj.v7i1.43896 canadian prosthetics & orthotics journal issn: 2561-987x feasibility of a yoga intervention in an inpatient limb loss rehabilitation program mayo et al., 2024 appendix a: likert survey post-yoga session 1) i felt calm and peaceful while doing yoga 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree 2) the yoga practice was easy to complete 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree 3) i felt pain during the yoga practice 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree 4) yoga improved the way i feel 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree 5) i felt anxious during the yoga practice 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree 6) i would recommend yoga to other patients 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree 7) i would like to do yoga again 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree 8) i felt safe while doing yoga 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree 9) i felt comfortable while doing yoga 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree 10) i feel overwhelmed by including yoga practice on top of my regular therapy 1-strongly disagree; 2disagree; 3neither agree nor disagree; 4-agree; 5-strongly agree https://doi.org/10.33137/cpoj.v7i1.43896 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 1 2024 research article nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i1.41780 1 nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 research article comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot nouman m1, apiputhanayut r2, narungsri t3, tipchatyotin s2, dissaneewate t2 1 sirindhorn school of prosthetics and orthotics, faculty of medicine, siriraj hospital, mahidol university, bangkok, thailand. 2 department of rehabilitation medicine, faculty of medicine, prince of songkla university, songkhla, thailand. 3 prosthetics and orthotics unit, department of rehabilitation medicine, faculty of medicine, prince of songkla university, songkhla, thailand. introduction charcot neuropathic osteoarthropathy, also known as charcot foot, is a serious complication that can result from any disorder associated with sensory or autonomic neuropathy. this complication leads to bone destruction, deformities, and ulcerations that can lead to amputation if left untreated promptly and properly.1 charcot foot is a major cause of morbidity and mortality in people with diabetes, with a 5-year mortality rate of 29% for those with charcot foot alone and up to 56.6% for those who have undergone major amputations.2 early diagnosis and treatment are crucial in preventing the progression of charcot foot and minimizing the risk of complications. charcot foot progresses through four stages: stage 0, characterized by asymptomatic or nonspecific symptoms and normal radiographs; stage 1, characterized by inflammation, swelling, and bone fragmentation visible on open access abstract background: charcot foot deformity, a severe complication of diabetes, involves neuropathy and abnormal peak plantar pressure in the midfoot and forefoot. however, orthotic interventions and shoe modifications are used to address the sequelae of charcot neuroarthropathy, offering different approaches to managing abnormal peak plantar pressure. objective: to compare the effects of three types of therapeutic offloading diabetic shoes; prefabricated, relasting, and double rocker-modified shoes on peak plantar pressure in the midfoot and forefoot of nonulcerated chronic charcot foot during walking. methodology: a repeated measure design involved 15 participants (40% males and 60% females) with a mean age of 60.73 years (sd=10.50), with charcot neuropathy. participants were provided with three types of shoes; prefabricated, relasting, and double rocker-modified shoes, each equipped with the same custom-made insole (cmi). plantar pressure was recorded while walking on level ground, focusing on the forefoot, midfoot, and hindfoot. the study also investigated additional variables affecting plantar pressure distribution, including the pressure-time integral and contact area. findings: the type of shoe had distinct effects on the distribution of plantar pressure. the double rocker-modified shoe particularly impacted forefoot pressure during the terminal stance phase of the gait cycle. peak plantar pressure at the forefoot increased by 5.37% with double rocker-modified shoes compared to relasting shoes. both double rocker-modified and prefabricated shoes reduced midfoot peak plantar pressure by 8.73% and 11.97%, respectively. similar trends were observed at the hindfoot, with reductions in peak plantar pressure. however, there were no significant differences in regional peak plantar pressure between the types of shoes except for the central forefoot (f (1.61, 22.5) = 5.69, p = 0.014). conclusion: there were no significant differences in the effectiveness of prefabricated, relasting, and double rocker-modified shoes in reducing and redistributing peak plantar pressure in high-risk areas of chronic charcot foot. article info received: september 25, 2023 accepted: july 30, 2024 published: august 17, 2024 citation nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i 1.41780 keywords neuroarthropathy, therapeutic shoe, charcot foot, diabetic foot, plantar pressure, custom made insole, orthotics, orthosis, gait * corresponding author: tulaya dissaneewate, department of rehabilitation medicine, faculty of medicine, prince of songkla university, hatyai, songkhla, thailand. e-mail: tulaya.p@psu.ac.th orcid id: https://orcid.org/0000-0003-2947-0375 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 1, article no.3. 2024 https://doi.org/10.33137/cpoj.v7i1.41780 https://doi.org/10.33137/cpoj.v7i1.41780 https://doi.org/10.33137/cpoj.v7i1.41780 mailto:tulaya.p@psu.ac.th https://jps.library.utoronto.ca/index.php/cpoj/index 2 nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 canadian prosthetics & orthotics journal issn: 2561-987x comparative analysis of offloading diabetic shoes for charcot foot nouman et.al, 2024 radiographs; stage 2, features decreasing inflammation and evidence of healing on radiographs.; and stage 3, noted for reduced swelling, joint stabilization, and new bone formation on radiographs. each stage needs customized treatment approaches, emphasizing the importance of early recognition and appropriate management to prevent progression and complications.3,4 treatment may involve immobilization, proper offloading devices, wound care, and surgery to repair or stabilize the affected foot.2,5 according to the 2017 global burden of disease research, the cost of caring for diabetic foot diseases and their complications in the united states was estimated to be around $237 billion.2 at present, there is no offloading device guideline for chronic charcot foot without plantar ulcer. proper therapeutic footwear is recommended to remove high pressure sites and in severe cases it also promotes the healing process for charcot foot with ulcer.6,7 to prevent chronic charcot foot ulceration, it is important to address gait dysfunction and biomechanical abnormalities that are common in people with diabetic neuropathic foot. these abnormalities often include an increase in the distribution of plantar pressure in sensitive areas. notably, maintaining plantar pressure below the critical physiological skin tolerance level generally acknowledged to be less than 200 kpa to reduce the risk of developing foot ulceration and re-ulceration.8 the peak plantar pressure in charcot foot mainly occurs in the midfoot area and redistribution of plantar foot pressure is considered the main method to reduce it. the footwear designs for redistributing midfoot peak plantar pressure are offloading pads, double rocker profile, proper shoe fitness, ankle-high, and knee-high offloading devices.9,10 double rocker modification of diabetic shoes uses the rocker-shaped sole in the shoe to help redistribute plantar pressure. there was a suggestion that the double rocker modification may be effective in offloading the peak plantar pressure at the deformed midfoot area in people with chronic charcot foot.8,11 currently, there is very limited literature that focuses on evaluating the effect of double rocker modification on the midfoot and forefoot area of chronic charcot foot without plantar ulcer. the extra width of the charcot foot can also be a problem for shoe fitting, as it may cause improper foot pressure loading during gait. to address this issue, a relasting technique may be used to reduce and redistribute peak plantar pressure. relasting shoes are recommended for people with foot deformities, arthritis, or other conditions that make it difficult to find proper shoes that fit comfortably.12 the relasting technique requires reshaping the insole, outsole and heel of the shoe to better match the shape and size of the wearer's foot, which involves expanding the width of the shoe in the midfoot area to provide wider total contact of the plantar surface of the foot with the shoe.13,14 however, to the author’s knowledge, there is currently no research evaluating the effect of the relasting technique on midfoot peak plantar pressure of chronic charcot foot without plantar foot ulcer. it was hypothesized that the relasting shoe with a custom-made insole (cmi) improves the offloading of the plantar aspect of the midfoot. therefore, the aim of this study was to compare the effectiveness of prefabricated, relasting, and double rocker modified shoes to reduce and redistribute peak plantar pressure in the midfoot and forefoot in chronic charcot without plantar ulcer. the outcome of this study may enhance the selection of suitable modified shoes to achieve optimal plantar pressure distribution, helping to prevent ulceration and re-ulceration in diabetic charcot neuroarthropathy. methodology study population fifteen patients with charcot neuroarthropathy were recruited from the rehabilitation outpatient clinic, the prosthetics and orthotics clinic, the diabetic clinic, and the songklanagarind hospital inpatient department. demographic characteristics including gender, body weight, height, shoe size, duration of diabetes, glycemic level, and foot-related problems were collected. the type of foot was determined with the foot posture index (fpi-6) by a clinician. fpi-6 is a clinical tool used to evaluate standing foot posture that provides a quantifiable measure, allowing clinicians to categorize foot types as supinated, neutral, or pronated. fpi-6 is widely recognized in clinical settings due to its reliability and ease of use, making it a valuable tool in both diagnostic and treatment planning processes for various foot-related conditions.15,16 this project was approved by the research ethics committee (rec.62-421-11-1), faculty of medicine, prince of songkla university. the inclusion criteria for all participants were an age range 18 to 80 years old, unable to feel the 10-gram monofilament, and able to walk at least 10 meters without any aid at a selfselected speed. participants were excluded if they had an active infected plantar foot wound, severe peripheral vascular disease, angina, dyspnea, major or minor lower limb amputation, and unstable vital signs. all participants signed written informed consent forms after understanding the whole experimental protocol. sample size determination the sample size of 15 was determined to provide 80% probability of a clinically meaningful difference detection of 40 kpa in peak plantar pressure between footwear conditions. the standard deviation was set at 50 kpa and the alpha level was set at 0.05.17 https://doi.org/10.33137/cpoj.v7i1.41780 3 nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 canadian prosthetics & orthotics journal issn: 2561-987x comparative analysis of offloading diabetic shoes for charcot foot nouman et.al, 2024 shoe and custom-made insole fabrication a certified orthotist fabricated custom-made insoles (cmi) from nora® 5 mm top layer, plastazote® 8 mm middle layer, and cork 10 mm base layer (figure 1-a). all patients received cmi with three footwear conditions, prefabricated shoes, double rocker shoes, and relasting shoes. the design of the prefabricated shoes (cdm*: cordoma international co., ltd.) are seamless lining with microcellular rubber outsole and a synthetic leather quarter. a certified orthotist modified the outsole of the prefabricated shoes with the addition of 10 mm ethylene vinyl acetate (eva) 30 shore a and reshaped it to make it a double rocker shoe with an angle of 10 degrees. moreover, relasting shoes are fabricated by cutting the middle of the shoes and adding polyurethane foam to provide more room for the midfoot in the mediolateral direction as shown in figure 1-b. a 5 mm thick layer of anti-slip microcellular rubber with 70 shore hardness was added to both double rocker and relasting shoes, resisting wearing out and provide high stability. * cdm is the brand of the prefabricated shoe used in this study. evaluation of plantar pressure the peak plantar pressure was collected during gait with the pedar-x® system (novel inc.; munich, germany), following the final fitting of the custom-made insole and three types of shoes. data were collected from three gait cycles along a 10-meter walkway with self-selected speed. before data collection, subjects walked along a 10-meter walkway at their comfortable speed to determine their walking speed and familiarize themselves with their shoes (figure 1-c). the sensors were placed under cmi and each sensor was calibrated according to the guidelines. novel multimask software (novel gmbh, munich, germany) was used to divide the foot area into 3 main regions, namely hindfoot, midfoot, and forefoot. the main three regions of the foot were divided into the medial hindfoot, lateral hindfoot, medial midfoot, lateral midfoot, medial forefoot, central forefoot, lateral forefoot, and big toe. peak plantar pressure, pressure-time integral, contact area, and pressure mapping during gait were evaluated with three types of shoes. to evaluate the impact of shoes on plantar pressure distribution, each participant wore three types of shoes with the same cmi. figure 1: charcot neuroarthropathic subjects are provided with a custom made insole (a), three types of shoes: prefabricated shoe; double rocker shoe, and relasting shoes (b), with the data collected during gait (c) from three main regions of foot as hindfoot, midfoot, forefoot. the forefoot is subdivided into four regions as follows: lateral forefoot (lff), central forefoot (cff), medial forefoot (mff) and hallux using masking software. the medial and lateral division is performed for the midfoot and the hindfoot (d). https://doi.org/10.33137/cpoj.v7i1.41780 4 nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 canadian prosthetics & orthotics journal issn: 2561-987x comparative analysis of offloading diabetic shoes for charcot foot nouman et.al, 2024 data analysis the data's descriptive statistics were presented as mean and standard deviation. statistical analysis was performed using prism 5.0 (graphpad software, san diego, ca, usa). analyses were conducted on the affected foot. a repeated measures anova was used to compare plantar pressure and derived parameters among prefabricated, double rocker, and relasting shoes to assess the impact of shoe modifications. post hoc comparisons were conducted where significant differences were found. statistical significance was set at p<0.05. results participant characteristics the participant demographics are shown in table 1. fifteen charcot neuroarthropathic patients (6 (40%) males and 9 (60%) females) were included with a mean age of 60.73 (sd=10.5) years were included. the mean body mass index was 25.13 kg/m2 (sd=2.52). charcot foot cases represented a long duration of diabetes (16.33 years (sd=6.05)) related to poor glycemic control, and the serum hba1c level was 7.88% (sd=0.85). the results also showed that 66.67% of patients with charcot arthropathy had a history of previous foot problems, such as foot ulcers or surgery. patients with stage 3 charcot arthropathy in this study showed a mean foot posture index (fpi-6) of 6.71 (sd=1.93). table 1: demographic data of charcot neuroarthropathic subjects. parameters mean sd age (y) 60.73 10.50 body weight (kg) 78.53 8.29 height (m) 1.56 0.04 bmi (kg/m2) 25.13 2.52 shoe size (eu) 40.40 1.25 duration of diabetes (y) 16.33 6.05 serum hba1c (% ngsp) 7.88 0.85 fpi-6 6.71 1.93 regional peak plantar pressure the midfoot showed higher peak plantar pressure with three types of shoes compared to the forefoot and hindfoot regions of the foot. moreover, the tendency for the peak plantar pressure was higher in the lateral midfoot compared to the medial midfoot, as shown in figure 2. figure 2: peak plantar pressure during gait for three types of shoes—double rocker, prefabricated, and relasting—across different foot regions. the data is divided into: (a) three main regions of the foot; (b) four forefoot regions; (c) two midfoot regions; (d) two hindfoot regions. significant differences are marked with an asterisk (*), indicating a p-value of less than 0.05. * double rocker prefabricated relasting double rocker prefabricated relasting double rocker prefabricated relasting double rocker prefabricated relasting https://doi.org/10.33137/cpoj.v7i1.41780 5 nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 canadian prosthetics & orthotics journal issn: 2561-987x comparative analysis of offloading diabetic shoes for charcot foot nouman et.al, 2024 the peak plantar pressure at the forefoot increased with double rocker-modified shoes compared to relasting shoes. furthermore, the maximum plantar pressure was highest in the lateral forefoot with double rocker-modified shoes compared to relasting and prefabricated shoes. however, the central forefoot and medial forefoot peak plantar pressure is reduced with double rocker-modified shoes and prefabricated shoes (table 2). there was no significant difference in regional peak plantar pressure among the measured variables except for the central forefoot with prefabricated and relasting shoes. regional pressure-time integral and contact area the pressure-time integral and contact area from three regions of the foot are shown in table 3. the pressure-time integral was highest at the midfoot compared to the forefoot and hindfoot using three types of shoes. the type of shoe has a minimum effect on the regional pressure-time integral. the overall contact area among the foot regions increased in the forefoot with all types of shoes followed by the midfoot and the hindfoot. pressure mapping during gait the pressure distribution across different phases of the gait cycle with various types of shoes reveals distinct patterns (figure 3). relasting shoes exhibit reduced pressure from initial contact to loading response. moreover, during midstance, a similar trend can be observed with relasting and double rocker shoes, but the pressure increased in the lateral forefoot with prefabricated shoes. during terminal stance, double rocker shoes promote a more centralized pressure distribution. conversely, prefabricated and relasting shoes resulted in higher lateral foot pressure. table 2: regional peak plantar pressure with three types of shoes pf: prefabricated; dr: double rocker and rl: relasting from different regions of the foot. foot region shoe type comparison mean diff. p-value geissergreenhouse's epsilon r2 f (dfn, dfd) forefoot pf vs. dr -6.60 0.609 0.047 rl vs. dr -10.30 0.604 0.818 0.69 (1.64, 22.90) rl vs. pf -3.65 0.910 toes pf vs. dr 10.10 0.254 0.097 rl vs. dr 0.963 0.991 0.818 1.50 (1.64, 22.90) rl vs. pf -9.09 0.219 medial forefoot pf vs. dr -9.99 0.391 0.100 rl vs. dr 2.86 0.894 0.860 1.56 (1.72, 24.10) rl vs. pf 12.90 0.352 central forefoot pf vs. dr -5.01 0.745 0.289 rl vs. dr 25.00 0.077 0.803 5.69 (1.61, 22.50) rl vs. pf 30.00 0.036 * lateral forefoot pf vs. dr -5.74 0.822 0.187 rl vs. dr -23.80 0.101 0.961 3.21 (1.92, 26.90) rl vs. pf -18.10 0.149 midfoot pf vs. dr -6.97 0.867 0.158 rl vs. dr 19.80 0.154 0.895 2.62 (1.79, 25.00) rl vs. pf 26.80 0.115 medial midfoot pf vs. dr -10.60 0.707 0.197 rl vs. dr 25.40 0.161 0.930 3.44 (1.86, 26.00) rl vs. pf 36.00 0.095 lateral midfoot pf vs. dr -1.09 0.995 0.116 rl vs. dr 17.60 0.296 0.945 1.83 (1.89, 26.50) rl vs. pf 18.70 0.162 hind foot pf vs. dr -16.50 0.666 0.099 rl vs. dr 11.10 0.564 0.748 1.55 (1.50, 21.00) rl vs. pf 27.60 0.253 medial hindfoot pf vs. dr -1.74 0.990 0.014 rl vs. dr 5.91 0.687 0.665 0.21 (1.33, 18.60) rl vs. pf 7.65 0.873 lateral hindfoot pf vs. dr -16.40 0.580 0.133 rl vs. dr 13.00 0.577 0.919 2.16 (1.84, 25.70) rl vs. pf 29.40 0.107 https://doi.org/10.33137/cpoj.v7i1.41780 6 nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 canadian prosthetics & orthotics journal issn: 2561-987x comparative analysis of offloading diabetic shoes for charcot foot nouman et.al, 2024 table 3: pressure-time integral and contact area with three types of shoes from three main regions of the foot during gait. foot region shoe type comparison mean diff. p-value geisser-greenhouse's epsilon r2 f (dfn, dfd) pressure-time integral forefoot pf vs. dr -6.96 0.301 rl vs. dr -10.80 0.210 0.866 0.140 2.28 (1.73, 24.30) rl vs. pf -3.86 0.698 midfoot pf vs. dr -2.94 0.919 rl vs. dr 5.18 0.764 0.947 0.037 0.54 (1.89, 26.50) rl vs. pf 8.12 0.634 hind foot pf vs. dr -9.46 0.493 rl vs. dr 2.87 0.767 0.678 0.101 1.58(1.36, 19.00) rl vs. pf 12.30 0.357 contact area forefoot pf vs. dr 0.41 0.947 rl vs. dr -1.43 0.513 0.851 0.089 1.37 (1.70, 23.80) rl vs. pf -1.84 0.135 midfoot pf vs. dr 2.29 0.275 rl vs. dr -0.94 0.769 0.971 0.159 2.64 (1.94, 27.20) rl vs. pf -3.22 0.132 hind foot pf vs. dr 1.25 0.349 rl vs. dr 0.62 0.676 0.748 0.099 1.55 (1.50, 21.00) rl vs. pf -0.63 0.675 note: pf: prefabricated, dr: double rocker, rl: relasting figure 3: pressure mapping during gait using double rocker, prefabricated, and relasting shoes. the data is shown for a single representative subject and includes: ic – lr: initial contact to loading response; mst: midstance; tst – psw: terminal stance to preswing. https://doi.org/10.33137/cpoj.v7i1.41780 7 nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 canadian prosthetics & orthotics journal issn: 2561-987x comparative analysis of offloading diabetic shoes for charcot foot nouman et.al, 2024 discussion this study found that relasting shoes increased the peak plantar pressure compared to prefabricated shoes and double rocker shoes at the central forefoot. however, opposite results were found in the lateral forefoot, as metatarsal heads are at high risk of ulceration and reulceration during gait. the peak plantar pressure was consistently less than 200 kpa with the modified shoes with custom-made insole at the medial midfoot and lateral midfoot, suggesting a potentially lower risk of ulceration in the midfoot region. these observations highlight the impact of shoe modifications on peak plantar pressure at specific regions, offering valuable insights into differential effects of various shoe types on foot pressure distribution. although the results did not reach statistical significance, they contribute to our understanding of how shoe modifications may affect plantar pressure distribution. the double rocker and prefabricated shoes demonstrated a reduction in peak plantar pressure in the midfoot and central forefoot areas compared to relasting shoes. this suggests a potential benefit in the offloading high-risk areas, which is critical to reduce the risk of ulceration.18 shoe modification considering pathological foot biomechanics is one of the most common practices in normal clinical practice for charcot neuroarthropathy.19,20 shoe modifications, including rocker bottom outsoles, are effective in further reducing and redistribute peak plantar pressure in various foot complications.21 rocker shoes provide a shorter contact time on heel strike and toe release, resulting in instability during gait in charcot neuroarthropathy.22 however, relasting shoes that provide a wider mediolateral space for the foot to accommodate provide better stability during gait, but resulted in increased peak plantar pressure, especially at the forefoot and hallux compared to a double rocker shoe.23 researchers investigated double rocker shoes in reduction of hindfoot and forefoot peak plantar pressure, while preventing excessive overloading at the midfoot. during gait, shoes with rocker sole peak plantar pressure decreased especially in the forefoot regions but increased in the midfoot.24 in this study, a similar pattern was observed in which there was a decrease in peak plantar pressure in both the forefoot and midfoot areas for patients with charcot neuroarthropathy. the findings align with previous research that indicates that these areas are particularly vulnerable in the charcot foot due to structural deformities and altered gait mechanics.16,25 the elevated pressure in these regions highlights the need for targeted interventions to better redistribute pressure during walking, particularly in the lateral midfoot and central to the medial forefoot. reducing peak plantar pressure while considering the importance of pressure-time integral to plantar ulceration, hence minimizing the combination of plantar pressure and the duration for which plantar pressure is applied to tissue, may be preferable than evaluating and reducing peak plantar pressure alone.26 in this study, shoe modification impacts both peak plantar pressure and pressure-time integral outcomes in the forefoot and midfoot regions. furthermore, the contact area in different foot regions did not show statistically significant differences. this suggests that the choice of shoe type with cmi may not significantly affect the contact area in specific foot regions.27 there were several limitations while investigating the plantar pressure distribution among three types of therapeutic designs with cmi. the barefoot data was not included in this study due to the severity and potential to harm the plantar soft tissue during gait. the width dimension of the sensor insole could affect the accuracy of plantar pressure, especially in the midfoot, in charcot neuroarthropathy. only one type of rocker shoe was compared; however, other designs might be effective for populations facing severe foot complications. further studies are required to evaluate the effectiveness of cmi and various shoe designs with varying rocker bottom sole angle and height on plantar pressure distribution in charcot neuroarthropathy. conclusion there were nonsignificant trends of pressure distribution and offloading in the high-risk areas of the foot using different types of shoe with cmi. prefabricated and double rocker shoes showed some effectiveness in reducing peak plantar pressure in the midfoot, and central forefoot, compared to relasting shoes. however, achieving significant offloading in areas of high risk, such as the lateral midfoot, remains a challenge, which requires further shoe modifications and consideration of the materials and design of cmi. these insights are crucial for improving footwear interventions for diabetic charcot neuroarthropathy, with the aim of reducing the risk of ulceration while maintaining foot functionality. acknowledgements the authors would like to thank the faculty of medicine, prince of songkla university, for their financial support. we also extend our gratitude to the participants for their involvement in this study. special thanks to miss phakatip cheunchoksan for her assistance and to the prosthetic and orthotic unit for providing the facilities. declaration of conflicting interests the authors declare no potential conflict of interest. https://doi.org/10.33137/cpoj.v7i1.41780 8 nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 canadian prosthetics & orthotics journal issn: 2561-987x comparative analysis of offloading diabetic shoes for charcot foot nouman et.al, 2024 authors contribution muhammad nouman: conceptualization, design, methodology, analysis, reviewing/revising manuscript, data interpretation. ravissada apiputhanayut: conceptualization, design, methodology, analysis, investigation, writing original draft, data interpretation, ethic certification application. tuanjit narungsri: conceptualization, methodology, reviewing/revising manuscript. suttipong tipchatyotin: conceptualization, supervision, methodology, reviewing/revising manuscript. tulaya dissaneewate: conceptualization, supervision, methodology, reviewing/revising manuscript, final manuscript approval. all authors have read and approved the final version of the manuscript. sources of support faculty of medicine, prince of songkla university, songkhla thailand. references 1.das l, rastogi a, jude eb, prakash m, dutta p, bhansali a. long-term foot outcomes following differential abatement of inflammation and osteoclastogenesis for active charcot neuroarthropathy in diabetes mellitus. plos one. 2021;16(11):e0259224. doi: 10.1371/journal.pone.0259224 2.armstrong dg, swerdlow ma, armstrong aa, conte ms, padula wv, bus sa. five year mortality and direct costs of care for people with diabetic foot complications are comparable to cancer. j foot ankle res. 2020;13(1):16. doi: 10.1186/s13047-020-00383-2 3.jeffcoate wj. charcot foot syndrome. diabetic med. 2015;32(6):760-70. doi: 10.1111/dme.12754 4.rosenbaum aj, dipreta ja. classifications in brief: eichenholtz classification of charcot arthropathy. clin orthop relat res. 2015;473(3):1168-71. doi: 10.1007/s11999-014-4059-y 5.crawford f, chappell fm, lewsey j, riley r, hawkins n, nicolson d, et al. risk assessments and structured care interventions for prevention of foot ulceration in diabetes: development and validation of a prognostic model. health technol assess. 2020;24(62):1-198. doi: 10.3310/hta24620 6.zhang y, lazzarini pa, mcphail sm, van netten jj, armstrong dg, pacella re. global disability burdens of diabetes-related lower-extremity complications in 1990 and 2016. diabetes care. 2020;43(5):964-74. doi: 10.2337/dc19-1614 7.wrobel js, najafi b. diabetic foot biomechanics and gait dysfunction. j diabetes sci technol. 2010;4(4):833-45. doi: 10.1177/193229681000400411 8.ahmed s, barwick a, butterworth p, nancarrow s. footwear and insole design features that reduce neuropathic plantar forefoot ulcer risk in people with diabetes: a systematic literature review. j foot ankle res. 2020;13(1):30. doi: 10.1186/s13047-020-004004 9.sawacha z, guarneri g, cristoferi g, guiotto a, avogaro a, cobelli c. integrated kinematics-kinetics-plantar pressure data analysis: a useful tool for characterizing diabetic foot biomechanics. gait posture. 2012;36(1):20-6. doi: 10.1016/j.gaitpost.2011.12. 007 10.chatwin ke, abbott ca, boulton ajm, bowling fl, reeves nd. the role of foot pressure measurement in the prediction and prevention of diabetic foot ulceration-a comprehensive review. diabetes metab res rev. 2020;36(4):e3258. doi: 10.1002/dmrr.3258 11.janisse d, janisse e. pedorthic management of the diabetic foot. prosthet orthot int. 2015 feb;39(1):40-7. doi:10.1177/ 0309364614535233 12.janisse dj, janisse e. shoe modification and the use of orthoses in the treatment of foot and ankle pathology. j am acad orthop surg. 2008;16(3):1528. doi: 10.5435/00124635200803000-00006 13.zwaferink jbj, custers w, paardekooper i, berendsen ha, bus sa. optimizing footwear for the diabetic foot: data-driven custommade footwear concepts and their effect on pressure relief to prevent diabetic foot ulceration. plos one. 2020;15(4):e0224010. doi: 10.1371/journal.pone.0224010 14.dahmen r, van der wilden gj, lankhorst gj, boers m. delphi process yielded consensus on terminology and research agenda for therapeutic footwear for neuropathic foot. j clin epidemiol. 2008;61(8):819-26. doi: 10.1016/j.jclinepi.2007.09.003 15.keukenkamp r, van netten jj, busch-westbroek te, nollet f, bus sa. users' needs and expectations and the design of a new custom-made indoor footwear solution for people with diabetes at risk of foot ulceration. disabil rehabil. 2021:1-8. doi: 10.1080/09638288.2021.2003878 16.redmond ac, crosbie j, ouvrier ra. development and validation of a novel rating system for scoring standing foot posture: the foot posture index. clin biomech. 2006;21(1):89-98. doi: 10.1016/j.clinbiomech.2005.08.002 17.hellstrand tang u, zügner r, lisovskaja v, karlsson j, hagberg k, tranberg r. comparison of plantar pressure in three types of insole given to patients with diabetes at risk of developing foot ulcers a two-year, randomized trial. j clin transl endocrinol. 2014 dec 1;1(4):12132. doi: 10.1016/j.jcte.2014.06.002 18.bolgla la, malone tr. plantar fasciitis and the windlass mechanism: a biomechanical link to clinical practice. j athl training. 2004;39(1):77-82. 19.sangeorzan a, sangeorzan b. subtalar joint biomechanics: from normal to pathologic. foot ankle clin. 2018;23(3):341-52. doi: 10.1016/j.fcl.2018.04.002 20.jastifer jr, gustafson pa. the subtalar joint: biomechanics and functional representations in the literature. foot (edinb). 2014;24(4):203-9. doi: 10.1016/j.foot.2014.06.003 21.fernando me, crowther rg, cunningham m, lazzarini pa, sangla ks, golledge j. lower limb biomechanical characteristics of patients with neuropathic diabetic foot ulcers: the diabetes foot ulcer study protocol. bmc endocr disord. 2015;15:59. doi: 10.1186/s12902-015-0057-7 22.lopez-moral m, molines-barroso rj, garcia-morales e, garciaalvarez y, alvaro-afonso fj, lazaro-martinez jl. predictive values of foot plantar pressure assessment in patients with midfoot deformity secondary to charcot neuroarthropathy. diabetes res clin pract. 2021;175:108795. doi: 10.1016/j.diabres.2021.108795 https://doi.org/10.33137/cpoj.v7i1.41780 9 nouman m, apiputhanayut r, narungsri t, tipchatyotin s, dissaneewate t. comparative analysis of three types of therapeutic offloading diabetic shoes with custom made insole on plantar pressure distribution in severe diabetic charcot foot. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.3. https://doi.org/10.33137/cpoj.v7i1.41780 canadian prosthetics & orthotics journal issn: 2561-987x comparative analysis of offloading diabetic shoes for charcot foot nouman et.al, 2024 23.polomé e, théveniau n, vigier c, dumas r, robert t. influence of different footwear on mediolateral stability during gait at different speeds in healthy people. comput methods biomech biomed engin. 2020;23(sup1):s226-s8. doi: 10.1080/10255842.2020. 1815318 24.arts mlj, waaijman r, de haart m, keukenkamp r, nollet f, bus sa. offloading effect of therapeutic footwear in patients with diabetic neuropathy at high risk for plantar foot ulceration. diabetic med. 2012;29(12):1534-41. doi: 10.1111/j.1464-5491.2012. 03770.x 25.bacarin ta, sacco ic, hennig em. plantar pressure distribution patterns during gait in diabetic neuropathy patients with a history of foot ulcers. clinics (sao paulo). 2009;64(2):113-20. doi: 10.1590/s1807-59322009000200008 26.gerrard jm, bonanno dr, whittaker ga, landorf kb. effect of different orthotic materials on plantar pressures: a systematic review. j foot ankle res. 2020;13(1):35. doi: 10.1186/s13047020-00401-3 27.praet sfe, louwerens j-wk. the influence of shoe design on plantar pressures in neuropathic feet. diabetes care. 2003;26(2):441-5. doi: 10.2337/diacare.26.2.441 https://doi.org/10.33137/cpoj.v7i1.41780 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 7, issue 2 2024 research article theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i2.44450 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 research article exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector theron b *, visagie s university of stellenbosch, division of disability and rehabilitation studies, faculty of medicine and health sciences, south africa. introduction lower limb amputations and prosthetic devices have been around for ages. over time, prosthetic materials and manufacturing techniques have developed from hand tooled wood and leather to metal, space age materials and computer aided design and manufacturing. these advances allow the manufacturing of prostheses that can restore user functionality to before or even above preamputation levels.1 however, more advanced materials are expensive and are often not used in lowerand middleincome countries, including south africa.2 according to a 2022 national census there are around 430,000 upper and lower limb prosthetic users in south africa.3 the average age of persons living with an amputation in africa and south africa is lower than in developed countries and often younger than 60 years of age.4 thus, the functional requirements of occupations must be considered when prosthetic components are selected.5 lower limb prosthetic services are mainly funded by one of four sources in south africa, namely public and private healthcare funding, as well as road, and work-related accident funding. successful fitting of lower limb prostheses is dependent on optimal prosthetic component prescription, based on a open access abstract background: evidence based guidelines can assist with prosthetic component selection and clinical intervention. there is limited evidence on lower limb prosthetic prescription guidelines in the south african private health care sector. objective: to explore the need for lower limb prosthetic prescription guidelines in the south african private healthcare sector. methodology: three main funders of lower limb prosthetics in the south african private healthcare sector (road accident fund (raf), workmen’s compensation fund (wca), and council of medical schemes (cms)) were explored using a case study design. data were collected from six regulatory documents, sixteen purposively sampled prosthetic users, who received services from these funders, and seven key informants. documents were assessed with the appraisal of guidelines for research & evaluation ii (agree ii), across six domains. data from users and key informants were collected with telephonic, semi-structured interviews guided by interview schedules. interview schedules were self-developed and tailored for each participant group. agree ii data were analyzed descriptively. inductive thematic analysis was used for interview data. findings: across cases, the “scope and purpose” domain scored the highest: 50% (wca), 47% (cms), and 22% (raf). “editorial independence” scored 0% for all three cases. other challenging domains were “applicability” (wca: 17%, cms: 6%, raf: 6%) and “rigour of development” (wca: 8%, cms: 25%, raf: 0%). the following three cross-case themes emerged from the interviews: “guideline availability and necessity” showed that guidelines were seldom used and that guidelines could be beneficial; “purpose of a lower limb prosthetic guideline” indicated that guidelines can support accessible, equitable, ethical, and transparent services; and “guideline development requirements” explained that an evidence based collaborative process, facilitated by an independent body should underscore guideline development. conclusion: evidence based, standardized, transparent guidelines will be beneficial to direct prosthetic service delivery in the south african private healthcare sector. the guidelines must be applicable, rigorously developed, and show editorial independence. article info received: december 11, 2024 accepted: february 4, 2025 published: february 12, 2025 citation theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v 7i2.44450 keywords prosthetist; user experience; prosthesis; funding policy; rehabilitation; lower limb amputation; south africa; prosthetic guidelines * corresponding author: mr. bennie theron, cpo, msc affiliation: university of stellenbosch, division of disability and rehabilitation studies, south africa. e-mail: benjetheron@live.com orcid id: https://orcid.org/0009-0006-0487-9050 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 2, article no. 8. 2024 https://doi.org/10.33137/cpoj.v7i2.44450 https://doi.org/10.33137/cpoj.v7i2.44450 https://doi.org/10.33137/cpoj.v7i2.44450 mailto:benjetheron@live.com https://orcid.org/0009-0006-0487-9050 https://jps.library.utoronto.ca/index.php/cpoj/index 2 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 comprehensive assessment of physical needs, life roles, and the environment in which the person is to function.6,7 the componentry must match the users’ abilities, goals, and daily use requirements.6 lower limb prosthetic componentry which accommodates activity level and user need are often expensive with funding not readily available in developing markets. however, cost saving should not be the primary focus when prescribing prosthetic componentry.7,8 a high initial financial investment increase quality adjusted life years9 and decrease future financial expenditure due to decreased secondary complications and increased product lifespan.10 thus, higher initial fiscal investment should not be seen in isolation as this investment has far-reaching positive effects on socio-economic and healthcare environments.9,10 clinical practice guidelines can assist with prescribing appropriate prosthetic components in accordance to user needs.8 clinical practice guidelines provide evidence-based recommendations intended to optimise patient care while considering the benefits and harms of alternative options.11 guidelines provide justification for interventions such as prosthetic component selection with transparency to all parties involved.8 comprehensive, effectively implemented guidelines can enhance quality and consistency of care.12 a lack of or inferior guidelines can cause gaps in service delivery that can disadvantage the end user.13 healthcare funders, prosthetists, rehabilitation specialists and prosthetic users must be involved in the development of lower limb prosthetic provisioning guidelines, as broad stakeholder involvement allows for transparent guideline formation beneficial to all parties.8,14 the quality of guidelines must be ensured through transparency and rigour during development. central to the process is the intended human activity based on functions and anatomical characteristics.8 empirical knowledge is essential. local medical device regulations should also be considered. lower limb prosthetic guidelines have been adopted in various sectors in different countries.6,8,15 however, information on the effect of lower limb prostheses guideline implementation is limited.15 anecdotal information suggests little national and/or inhouse guidelines to guide prosthetic service delivery in south africa. usually, componentry is prescribed and funded based on the user`s activity level as determined by the amputee mobility predictor with/without prosthesis (amppro/ampnopro).16 furthermore, certified prosthetists and orthotists (cpos) clinical expertise and experience guides prosthetic prescription. clinical knowledge plays an important role in appropriate prescription but must be supported by evidence.6,8 not including evidence in prescription decisions may lead to deviation in prosthetic prescription as well as over-or under treatment. these challenges prompted this study with the aim to explore and describe the need for a lower limb prosthetic prescription guideline in the private healthcare sector in south africa. conceptual framework the updated appraisal of guidelines for research and evaluation (agree ii) provided a framework for the study as well as a document appraisal tool (figure 1).14 the agree ii framework can be used to develop guidelines and evaluate the quality of guidelines. geertzen et al.8 successfully used the agree ii to formulate a lower limb prescription guideline in the netherlands. figure 1: the six domains and domain items of the agree ii (adapted from brouwers et al.14). scope & purpose • guideline obejectives are defined. • health aspects covered are described. • target population is described. stakeholder involvement • development group included individuals from all relevant professional groups. • target pupolation input was sought. • target users are clearly defined. rigour of development • evidence was searched systematically. • in and exclusion criteria in selecting evidence were clearly described. • methods used to fomulate recommendations were described. • health benefits, side effects and risks have been considered. • explicit link between recommendations and supporting evidence. • external experts reviewed the guidlelines before publication. • an updating procedure is described. clarity of presentation • recommendations are specific and unambigouos. • different managment options are presented. • key recommendations are easily identifiable. applicability • facilitators and barriers to application is described. • provides advice on how recommendations can be implemented. • resource implications have been considered. • monitoring and/or auditing criteria are included. editorial independence • views of the funding body did not influence content. • competing interests of development group members have been recorded and adressed. https://doi.org/10.33137/cpoj.v7i2.44450 3 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 methodology an exploratory case study methodology was used because it provides insight and facilitates understanding of complex phenomena within a defined context. it can explore how similar issues are dealt with in different contexts and how context influences the phenomenon being researched.17 qualitative and qualitative data were collected as illustrated in figure 2. the three cases that were explored in the study are the main funders of lower limb prosthetics in the south african private healthcare sector: • road accident fund (raf) • workmen's compensation fund (wca) • council of medical schemes (cms) raf: the raf (table 1) is a social insurance service, funded through a national fuel levy, and provides compulsory cover to all road users in south africa. once liability has been accepted, the raf shall “compensate for costs of the future accommodation of any person in a hospital or nursing home or treatment of or rendering of a service or supplying of goods.”18 goods and services include lower limb prosthetic services. coverage is provided for the remainder of the beneficiary’s life. for the first time, the raf published a product list for reimbursement in 2022.19 wca: the wca (table 1) administers the compensation for occupational injuries and diseases act no 130/199320 as amended by the compensation for occupational injuries and diseases act no 61/1997.21 the act provides compensation for disablement or death caused by occupational injuries or diseases. employees who sustained a lower limb amputation due to a work-related injury, are automatically covered for life once liability has been accepted. an annually published gazette provides guidance on prosthetic prescription, eligibility criteria, renewal periods, application forms and reimbursable professional fees and products.16 the 2023 gazette included technologically advanced prosthetic componentry for prescription.16 cms: the cms (table 1) is a statutory body whose operational objectives are described in the medical schemes act (act 131 of 1998).22 the cms regulates and monitors the functioning of medical schemes in south africa. lower limb prosthetics are covered under prescribed minimum benefits (pmb), the minimal level of care that the medical scheme is obliged to fund without copayments or deductibles. prosthetics should be funded in the private sector at least equal to what is provisioned for in the public sector.23,24 cms has published a guideline document on amputations (non-specific) which outlines the basic coverage that medical schemes should offer to their members.25 raf wca cms quantitative methodology qualitative methodology case study methodology: post positivism paradigm semi structured interviews: key informants from the private prosthetic sector expert purposive sampling cases lower limb prosthetic policy appraisal: agree ii instrument semi structured interviews: lower limb prosthetic users: deviant purposive sampling accessed through prosthetists in private practice conceptual framework: agree ii tool figure 2: an illustration of case study methodology through a mixed method approach used in the study. https://doi.org/10.33137/cpoj.v7i2.44450 4 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 the public healthcare sector was excluded from the study as the purchasing methods and service delivery mechanisms differ in each of the nine provinces in south africa and differ from methods used in the private sector. the three private funders have a homogenic approach to funding lower limb prostheses. the public healthcare sector receives funding from the national healthcare budget of the department of health (doh) which provides the general public with access to prosthetic care (although basic). the doh has various orthotics and prosthetic facilities in each province where cpo’s are employed by doh to manufacture and fit prosthetic devices. these facilities are fully financially dependent on doh for (but not limited to): infrastructure, facility maintenance, human resources, orthotic and prosthetic components and consumables, as well as general running costs of an orthotic and prosthetic facility. data sources data were collected from documents, key informants, and lower limb prosthetic users. documents were retrieved from the public domain, as a formal request for lower limb prosthetic prescription guidelines, regulatory frameworks, and/or policies to the three entities yielded no response. seven key informants were purposefully sampled using expert purposive sampling.26 they included management level employees from the three cases, as well as individuals from educational institutions, professional bodies, and prosthetic component suppliers. the key informants have knowledge and experience working in the sector and could give insight into current practices and the need (or not) for a lower limb prosthetic prescription guideline. the contact details of these individuals are available in the public domain. they were contacted via phone by the researcher. the aim of the study and their role were explained, also that the interview would be audio recorded for accurate transcriptions. after willingness to participate in the study was expressed, a study information leaflet and consent form for virtual data collection were sent via email. once the signed informed consent was received, a telephonic interview was scheduled. sixteen lower limb prosthetic users, whose prostheses were funded by one of the three cases, were sampled through maximum variation purposive sampling. the study population of lower limb prosthetic users was unknown and could not be accessed through a database. cpo’s working in the private healthcare sector in various geographical regions of south africa were contacted and requested to reach out to possible lower limb prosthetic users to participate in the study. twenty-one possible participants were identified by cpos based on the inclusion and exclusion criteria. cpos asked verbal consent to share their contact information with the researcher. prosthetic user inclusion criteria: • persons with major lower limb amputation/s (unilateral or bilateral). • persons who received a lower limb prosthesis at least six months before commencing data collection. • insured with the raf, wca or a private medical scheme registered with the cms. • ability to communicate in any of the official languages in south africa. prosthetic user exclusion criteria: • lower limb prosthetic users who had stroke, spinal cord injury, or traumatic brain injury. • persons who could not participate in a virtual or telephonic interview due to lack of access to necessary hardware or speech impairments. • persons who could not provide informed consent due to cognitive impairments. the researcher contacted all twenty-one possible participants by telephone; five did not respond. the study was explained to them, and the provisional consent for their participation in the study was obtained. the study’s information leaflet and consent form for prosthetic users were sent to participants via email. sixteen individuals completed the consent form and sent it back to the researcher, whereafter an appointment for an audio recorded interview was made. lower limb prosthetic table 1: overview of lower limb prosthetic funders in south africa. raf wca cms public health sector reimbursement system medical schemes professional fee tariff list + nappi codes (medicine, consumables and devices) annual published government gazette medical schemes professional fee tariff list + nappi codes (medicine, consumables and devices) subsidised by government with patient co-payment based on income* responsible department department of transport department of employment and labour department of health department of health percentage of population eligible for coverage 100% 67% (aged between 1564)** 15%*** 100% funding method fuel levy compulsory deduction from salary or wage medical schemes via members private monthly contributions national health budget * https://www.westerncape.gov.za/general-publication/western-cape-government-hospital-tariffs-overview?toc_page=3 ** https://census.statssa.gov.za/#/ *** https://www.medicalschemes.co.za/preliminary-industry-trends/ https://doi.org/10.33137/cpoj.v7i2.44450 https://www.westerncape.gov.za/general-publication/western-cape-government-hospital-tariffs-overview?toc_page=3 https://census.statssa.gov.za/#/ https://www.medicalschemes.co.za/preliminary-industry-trends/ 5 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 users who were both satisfied and dissatisfied with their prosthesis were included in this study.26 to further ensure variation, prosthetic users were sampled to include all sexes, age groups, major lower limb amputation levels and urban and rural lower limb prosthetic users. data saturation was reached after sixteen interviews. although lower limb prosthetic users of only six out of the nine provinces in south africa were interviewed, the cohort included both urban and rural lower limb prosthetic users. the three cases studied operate the same across all provinces thus the experiences of lower limb prosthetic users would be similar. as the study was novel, there was no available questions which could have been accessed or informed the interview schedule. the interview questions were formulated based on the agree ii tools six domains and researchers experience in the industry. all interview schedules were in english, and interviews were conducted in both english and afrikaans (although any official south african language could have been accommodated if the need had arisen). data collection the agree ii reporting checklist was used to appraise documents. the agree ii consists of 23 items in 6 domains, scored on a scale from 1 (strongly disagree) to 7 (strongly agree). domain scores are calculated by summing item scores and scaling the total as a percentage of the maximum score.27 higher agree ii scores indicate higher quality guidelines. a guideline can be “strongly recommended” if four (or more) out of the six domain scores are above 60%.28 guidelines can be “recommended with provisions or alterations” if at least two out of the six domains scored between 30%-60%. items of the agree ii are valid and useful. the tool is “appropriate, easy to use, and helpful in differentiating guidelines of varying quality”.29 the two authors appraised the documents individually after which domain averages were calculated. qualitative data were collected through semi-structured, telephonic interviews, by the first author between october 2022 and april 2023. two interview schedules, informed by the agree ii, were developed for the key informants and users respectively. prosthetic user questions: • can you please describe the process of getting your current prosthesis? • what information was available to help you understand the process? • to what extent was your opinion on the type of prosthesis and components considered? • what could your funder have done differently in this process? • what advice do you have for other new lower limb amputees in accessing prosthetic care? key informant questions: • what challenges do we experience in lower limb prosthetic prescription and provision in the south african private healthcare sector? • what role can lower limb prosthetic guidelines play in prosthetic prescription in the south african private healthcare sector? • what would the ideal situation be in the prescription of lower limb prosthetics in the private healthcare market? data analysis data were analyzed for each case individually after they were integrated. data from the agree ii reporting checklist were collated and summarised. inductive thematic analysis was used to analyze qualitative data. after coding, provisional themes were developed separately by the authors. consensus was reached and themes were named and defined. rigour case study methodology allows different facets and views of a phenomenon to be explored, through multiple cases and in-depth analysis of multiple information sources to increase the credibility of the study.17 credibility was further enhanced through purposive sampling and data saturation.30 transferability was supported by describing the cases and providing demographic information on participants.17 confirmability was supported through triangulation and researcher reflexivity.30 dependability was sought through triangulation, researcher reflexivity and the presentation of limitations.30 ethical considerations ethical approval was obtained from the health research ethics committee at stellenbosch university (n22/01/002). participation in the study was voluntary. the informed consent form was sent to participants electronically for them to sign and return before the interview was scheduled.31 results document analysis the following documents were assessed: • road accident fund act (act 56 of 1996),18 and road accident fund medical tariff (19 august 2022, no 46747).19 • the compensation for occupational injuries and disease (coid) act (act 130 of 1993)20 and the annually published government gazette (volume 693, march 2023. no 48299).16 • the medical schemes act, (act 131 of 1998)22 and the cmscript amputations (issue 2 of 2023).25 https://doi.org/10.33137/cpoj.v7i2.44450 6 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 the highest score overall was 50% (wca, scope and purpose). all three cases scored 0% for editorial independence. two wca domains, scope and purpose and the clarity of presentation, scored 50% and 44% respectively. two cms domains, scope and purpose and stakeholder involvement, scored 47% and 30%, respectively. raf scores were below 30% in all domains (table 2). demographic information of participants prosthetic users ages ranged from 4 to 66 years. in the instance of minors, their mothers were interviewed. the average time since amputation was 12 years (table 3). key informants were employed between two and fifteen years in their current role, which provided the basis for sampling (table 4). table 2: agree ii domain scores. domains raf score wca score cms score 1-scope and purpose 22% 50% 47% 2-stakeholder involvement 11% 22% 30% 3-rigour of development 0% 8% 25% 4-clarity of presentation 19% 44% 25% 5-applicability 6% 17% 6% 6-editorial independence 0% 0% 0% recommend for use no with modifications with modifications table 3: demographic details of user participants. patient id sex age* occupation amputation level years since amputation year of amputation reason for amputation province rafu1 male 29 mechanic transtibial 5 2018 motorbike accident gauteng rafu2 male 28 lecturer engineering trans-femoral 12 2011 motorbike accident north west rafu3 female 35 unemployed trans-femoral 4 2019 pedestrian accident western cape rafu4 male 16 scholar trans-femoral 8 2015 pedestrian accident western cape rafu5 female 63 administrator transtibial 18 2005 pedestrian accident gauteng rafu6 male 47 electrician knee disarticulation 5 2018 motorbike accident gauteng wcau1 male 53 unemployed transfemoral 8 2015 work related car accident eastern cape wcau2 male 52 supervisor security transfemoral 16 2007 gunshot western cape wcau3 male 59 unemployed transtibial 3 2020 falling at work western cape wcau4 male 25 unemployed knee disarticulation & transtibial 5 2018 aerospace related incident gauteng wcau5 male 66 pensioner transtibial 41 1982 work related car accident kwa-zulu natal cmsu1 male 6 scholar bilateral transtibial 6 2017 congenital gauteng cmsu2 female 5 scholar transtibial 5 2018 congenital / infection gauteng cmsu3 male 39 personal trainer transfemoral 1 2022 infection mpumalanga cmsu4 male 60 project manager transtibial 4 2019 diabetic mpumalanga cmsu5 male 50 managing director bilateral transtibial 50 1973 congenital western cape * years. table 4: demographic details of key informants. id sex age type of organization role at organisation professional qualification time at organization* province ki1 female 42 social insurer acting general medical manager medical doctor 4 gauteng ki2 male 50 regulatory body former senior clinical manager medical doctor 6 gauteng ki3 male 48 professional body chairman – professional body & practicing cpo orthotist & prosthetist 3 gauteng ki4 female 42 social insurer chief director – rehabilitation & orthotics occupational therapist & mba 4 gauteng ki5 male 34 prosthetic device supplier head of government sales & stakeholder management business management 6 gauteng ki6 female 50 academia senior lecturer orthotist & prosthetist 15 gauteng ki7 female 40 prosthetic device supplier medical device supplier owner psychology 2 gauteng * years https://doi.org/10.33137/cpoj.v7i2.44450 7 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 emerging themes three themes with subthemes were identified as shown in table 5. table 5: themes and subthemes identified from participant data. theme subthemes guideline availability and necessity purpose of a lower limb prosthetic guideline a. guiding clinical prescription responsive to user needs. b. supporting adequate funding in a timely manner. c. equity, transparency, and fair reimbursement. d. multi-disciplinary rehabilitation. e. case managers. f. information sharing. g. a list of preferred practitioners. guideline development requirements h. driven by an independent entity. i. collaboration and communication. j. use of available evidence. theme 1: guideline availability and necessity key informant (ki2) indicated that a lower limb prosthetic guideline will “streamline the care and unify the care such that the minimum standard is applicable across all sectors”. ki3 felt that guidelines, “make it a lot easier and have a lot less red tape whereby you can still provide your patients with a reasonable prosthesis”. key informants also indicated the current insufficiency of guidelines. ki3 explained that there “isn’t norms, and the norms that are there are old and antiqued”. although some funders might have guidelines, “they don’t like to share their guidelines, and keep it as their intellectual property” (ki4). the lack of guidelines was confirmed by users of all three cases. lengthy procedures and complex requirements were evident. “if they can tell you from point a, i want abcdef, you can send everything one time…it is very difficult…it is very complicated” (cmsu2). “beyond reason, takes months. it can even take up to a year…everything is a process…[which] makes you vulnerable” (wcau2). “it’s a story. actually, it is a fight” (rafu2). theme 2: purpose of a lower limb prosthetic guideline a. guiding clinical prescription responsive to user needs: a prosthesis must support individual function within a specific context and life role requirements. users need their prosthesis to enable them to participate in activities meaningful to them. therefore, prosthetic guidelines must ensure “patients get the appropriate device, most clinically accurate for their diagnosis” (ki4) and “activity level” (ki7). prosthetic component prescription should “not be a blanket approach” (ki3) and not be driven by cost containment. “reintegration vocationally, into the community, into family, is the one measure which any cost containment initiative should be able to measure” (ki1). keeping in mind that “employment and vocational needs that are unique” (ki1), persons with lower limb amputations “might not be able to return to work and live the fullest life because they are being kept back by what they are getting from their medical aid, government institution or workmans compensation” (ki7). users concurred that they did not always get the most appropriate components to support their functioning. “i want a knee that can squat, that can run. i am still young, i want to run…i want to feel safe, because i used to fall at the mall… i just stood up and pretend like i`m okay, but when i get home, i feel like ohhh man” (wcau4). since the same person has different mobility needs due to different lifestyle requirements, a second prosthesis with components that support specific activities such as sport should be considered. funders frequently do not make provision for a secondary prosthesis. thus, persons with lower limb amputations “use the prosthesis [for activities it was not meant] and suffer the consequences later” (ki3) or the cpo “try create that one shoe fits all hybridized prosthesis which might not be perfect for their daily ambulation, but at least allow them to attain some form of higher activity with regards to sporting events” (ki3). a secondary prosthesis is also important when the primary prosthesis needs repairs. as explained by rafu5, “if i take the one in for repair, i use the other one”. b. supporting adequate funding in a timely manner: long waiting times were bemoaned by users and key informants alike. “patients’ cases go on for years before they can get help” (ki5). “quite a lengthy procedure” (wcau5). “the process takes flippen [slang for very] long” (rafu2). ki3 explained that “there is one big challenge at the moment, and that would be funding.” although private funders fund high end prosthetic components, “you might wait a while to be funded for it” (ki7). the biggest concern was “giving the correct prescription to the patient” and “at least ensuring to get reimbursed for the correct prescription made” (ki3). this opinion was confirmed by ki7, “funding is the main stumbling block between a patient being able to walk or being wheelchair bound or on crutches”. “practitioners are often limited to give the patient the best possible solution due to limited funding which limits what the patient can achieve” ki7. the raf “…will try to play out as long as they can before they pay” (ki5). https://doi.org/10.33137/cpoj.v7i2.44450 8 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 users agreed. “the medical aid disappointed me…because they did not pay for the leg…if they could only fund the thing…they must at least fund a mechanical knee in full” (cmsu3). in this instance the medical insurance paid 11% of the total cost of the prosthesis. the use of the prescribed minimum benefit when funding is supplied by medical insurance schemes was inconsistent and confusing. “there is no standard approach” (ki5) and “it (pmb) is about interpretation and manipulation of interpretation…they try and make it as difficult as possible” (ki3). c. equity, transparency, and fair re-imbursement: guidelines can assist in ensuring fair, non-discriminatory treatment of all people with lower limb amputations. as indicated by ki1, “unified guidelines that speak to standardized care where all stakeholders can be held accountable should the guidelines not be adhered to…ethical conduct on the part of all concerned where the shift moves away from what prosthesis provides the most financial gain to what prosthesis provide the most in the patients activities of daily living” (ki1). having standard guidelines for the provisioning of lower limb prostheses could be a win for all stakeholders involved. “rules and regulations with the costing done correctly which will be saving money, patients getting better outcomes and suppliers getting better sales and reduce waste and abuse across the industry” (ki3). “preventing fraud, over billing and unbundling” (ki4). overprescription, related to prescribing more expensive rather than appropriate components, is a reality in the south african prosthetic industry “where prescription is written more for financial gain than to address the specific needs of the patient” (ki5). rafu6 concurred and explained an additional challenge related to overprescription. “there are prosthetists who only prescribe the most expensive knees although the patient does not have the capability of using it. this makes it difficult for other persons with lower limb amputations to access such more expensive prosthetic knees when they actually need it”. the reimbursement of products historically “were not (correctly) set up from the start where there was just no transparency. any product could be listed at any price. it was a free for all and that is where the mistrust in the industry from the funders side” (ki7) emanated from. it seemed as if unethical behaviour that involved financial gain were practiced by various stakeholders, not only prosthetists. “with raf, it’s the lawyers. everyone is out there for money, and they forget about the patient, which becomes a struggle for the patient to get a prosthesis” (ki5). “you can get a prosthesis, but you have to pay over funds into an account whereafter you will receive authorization. if you don’t pay funds or don’t put anything on the table, you get pushed to the side…the raf has fired a lot of case managers, i think due to corruption” (rafu6). “there is an incredible amount of corruption unfortunately. bribery is a big problem. unfortunately, prosthetics are expensive commodities. at the end of the day, the guys do unethical, corrupt things to get the business and to the detriment of the patient.” patients get bribes “in the form of cash incentive, fridges, cellphones that sort of things…. this undermines the profession, undermines the integrity of what we stand for and undermines the patient’s rehabilitation outcome at the end of the day” (ki3). d. multidisciplinary rehabilitation: the importance of receiving rehabilitation from a multi-disciplinary rehabilitation team was stressed. “treating a patient holistically and understanding that the patients are full-on individuals that has different aspects to them” (ki1) needs to be addressed by “guidelines across the board which will unlock funding, treatment and rehabilitation” (ki3). “there should be a dedicated program set out for any person with a lower limb amputation that covers enough sessions until that person is strengthened and reconditioned to probably where he was when he was still healthy and functional” (cmsu5). e. case managers: throughout the interviews it became evident that case managers can play an important role in accessing prosthetic care. the performance of the case manager mirrored the users’ experience of accessing care. rafu5 had the same “case manager for longer than 10 years, it goes quick, i don’t struggle”. rafu2 shared a different scenario. “it took me a year to get a new case manager [after relocating to another province]. their services were really bad”. this caused delayed access to prosthetic care and rafu2 personally funded the cost of prosthetic consumables for “more than two years”. key informants also felt that raf case managers might in some instances not fulfil their roles as required. “case managers are often really frustrating, some of them are really not good. files get lost and patients are not contacted” (ki3). ki7 stated, “they don’t answer phones. there is just no leadership and pride in what they are doing”. f. information sharing: ki1 recommended “full-scale awareness to claimants to know what they qualify for according to the guidelines and to know what benefits are due to them…increase level of awareness, information and the entitlement to quality medical care” (ki1). wcau5 indicated guideline should include information on: • “best way” to go about accessing prosthetic care. https://doi.org/10.33137/cpoj.v7i2.44450 9 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 • “time periods” for when new components, sockets and consumables like liners, prosthetic socks, prosthetic foot covers etc. can be accessed. • “what is out there” in terms of components for possible prescription. g. a list of preferred practitioners: a guideline can also provide a list of preferred practitioners who provide high quality prosthetic care. most people with a lower limb amputation have no reference point on how to identify a good cpo. “you start to find your way through to somebody…and you find oh no, he is not good anymore. so, you go for a second opinion and somebody even better or probably even worse” (wcau5). cpos play an intricate role in the provisioning of prostheses and the experience of persons using a lower limb prosthesis. “this is somebody you need to be able to go on a journey with because that journey is probably going to be for the rest of your life” (cmsu5). “get yourself a good prosthetist…it is a big deal” (rafu2). theme 3: guideline development requirements h. driven by an independent entity: guidelines should “try to find common ground and alignment of different interests” (ki2). thus, an independent body should be established to provide a “neutral platform to engage” (ki1). the entity should “have no favoritism towards provider or funder and develop a guideline that shows fairness towards all parties, but most importantly showing value towards the patient” (ki4). i. collaboration and communication: ki3 argued that successful guideline development should be an “industry collaboration” (ki3) following “a multi-faceted approach” (ki3) with “a whole team” (ki3). a “multidisciplinary” (ki6) and “multi-stakeholder approach is important” (ki1). this group of “role players need to come in one room and develop something that will work best for the patients and for everyone else in the value chain” (ki5) with the “more stakeholders the better” (ki6) where all “agree on common good” (ki2). stakeholders include funders, service providers and users. “the funder cannot do it without the service provider, and the service provider cannot do it without the funder” (ki1). academia was also seen as a “major stakeholder” (ki2) as they can do research on “cost effectiveness, sourcing of materials to manufacture prosthetics and provide training” (k12). j. use of available evidence: key informants agreed that it was not necessary to “reinvent the wheel” (ki3) as “cross referencing what we want to do and what is done internationally” (ki3) can be done as “international literature and experiences, drives a lot of evidence” (ki1). local guideline formation can “borrow knowledge and expertise” (ki1) from international counter parts where there “is a strong drive on evidence-based medicine” (ki1). the unites states of america and australia were identified to “have similar situations to the south african private healthcare environment” (ki4) and have “guidelines which can be adjusted to fit the south african context” (ki6). “the international society of prosthetics and orthotics which have good recommendations” (ki6) can also be approached for guidance. discussion although the three cases were guided by different acts, they have the same mandate to fulfil – provisioning of lower limb prostheses. thus, it is not surprising that findings were similar and overlapping. findings support the development of an evidence-based guideline for provisioning of lower limb prosthetics in the south african private sector that can guide equitable, fair service delivery and provide clarity on treatment pathways, available components and prescription criteria as summarised in table 6. based on agree ii findings current raf guidelines cannot be recommended for use in the provision of lower limb prostheses while wca and cms guidelines can be recommended for use with modifications.28 however, acts and government gazette publications have a more table 6: summary of study findings. finding: there is a need for developing a uniformed evidence-based guideline for the provisioning of lower limb prostheses in the south africa private healthcare sector utilizing the agree ii tool (main framework) and delphi technique (for consensus purposes). addressing: providing clarity on: ▪ equitable service delivery. ▪ enhance and promoting ethical practice and industry transparency. ▪ fair reimbursement. ▪ prohibiting over-prescription and bribery. ▪ encouraging economic activity of lower limb prosthetic users. ▪ incorporating multiple stakeholder involvement and processes to increase guideline development rigour. ▪ treatment pathway for lower limb prosthetic users to follow. ▪ available prosthetic components for prescription. ▪ criteria for a new prosthesis and socket refits. ▪ prescription on secondary prosthesis, repairs and maintenance of devices, sport and recreational prostheses. ▪ rehabilitation treatment pathways. https://doi.org/10.33137/cpoj.v7i2.44450 10 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 overarching purpose than providing service delivery guidelines. therefore, the low scores of the documents that were appraised with the agree ii were hardly surprising. however, the low scores made it clear that these documents could not fulfil the role of a prosthetic service delivery guideline. the interviews confirmed this, and the data identified inconsistencies in products provided, uncertainty of processes, long waiting times and insufficient funding of products that point to a need for service delivery guidelines. previous work suggested that guidelines can address these challenges.8,12,32 in south africa resources are constrained and idealistic prescription to provide all lower limb prosthetic users with everything is not feasible. thus, a guideline should weigh costs against function. however, as far as possible every user should be supplied with components which can best support their physical, vocational, recreational, and environmental requirements.5,12 the guideline should also provide guidance regarding the funding of a second prosthesis. in healthcare systems that fund secondary prostheses, provision of secondary prostheses are more prevalent among younger, transtibial prosthetic users with high mobility levels, who had non-dysvascular amputations.33 the provisioning of sport and recreational prostheses are cyclic in nature as a lack of an activityspecific prosthesis leads to lack of participation and lack of participation leads to inadequate justification for an activityspecific prosthesis.32 rejecting applications without providing sound reasons or applications taking an inordinately long time to fund are determinantal to users’ psychosocial experiences,7,9,34 quality of life34 and economic activity.5,35 for children specifically, developmental milestones must be met to ensure optimal ongoing physical and emotional development.36 not replacing prosthetic limbs timeously to accommodate growth and development needs can cause irreparable harm.36 users described being unsure of processes and dependent on cpos to secure funding. the level of support needed from cpos might have been necessitated through unclear procedures, bureaucratic processes, stalling techniques, and red tape. a guideline written in plain language can help to facilitate user knowledge8 and thus user centered care.37 unfortunately, dependence on cpo’s increases the administration burden of cpo practices, the size of the administrative staff complements, and the cost of supplying a prosthesis. case managers can reduce the administrative burden on cpos. they can guide the processes, provide a point of contact, provide feedback, assess user needs and much more. however, the funder as employer should ensure that case managers provide high-quality services and follow the correct procedures. over and above guidelines, this can be guided by standard operating procedures and disciplinary action. a guideline should be in line with the study findings and agree ii domains.27 the domains must be clearly identifiable throughout the guideline to ensure that the objectives, the issue dealt with (i.e. prosthetic service provision) and the target population are clearly described. all relevant stakeholders (including the target population) must be involved in the development of such a guideline. evidence used to develop the guideline must be rigorous and used appropriately. the recommendations must be presented clearly and without ambiguity. different pathways and possible deviation in some cases must be presented. the guideline must present strategies that can help its implementation as well as facilitators and barriers to implementation, including resource allocation and monitoring strategies. competing interests of stakeholders and the view of the funder must not influence the guidelines. as indicated by participants and in the background, guidelines have been developed in other settings (mostly high-income countries).8,12,32 information from these can be used to assist the development of guidelines in the south african private sector. however, caution must be used as the contexts differ and sadeghi-demneh et al15 found that none of the guidelines currently in use internationally have been researched to determine their impact on service delivery. limitations the low numbers of cpos and rehabilitation team members as participants could have limited a broader understanding of the available guidelines available for rehabilitating and providing prostheses for individuals with lower limb amputation. as the study was novel, no existing validated interview schedules were available and had to be selfformulated by the authors. conclusion the study highlighted the need for evidence-based guidelines to guide prosthetic service delivery in the south african private sector. guidelines rather than protocols are recommended because guidelines are flexible and allow clinical judgement and adaptation to individual user needs. guideline development must be driven by an independent body trusted by all stakeholders and follow a patient centric, transparent, equitable approach involving multiple stakeholders. the agree ii tool and delphi technique (where consensus has not been reached) can be used to facilitate the development process. further research should be conducted to guide the formation of a standardised lower limb prosthetic guideline facilitated by an independent body (consisting of multistakeholders in the industry) which provides the opportunity for adoption by all three cases studied. a method of https://doi.org/10.33137/cpoj.v7i2.44450 11 theron b, visagie s. exploring the need for lower limb prosthetic guidelines in south africa's private healthcare sector. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 8. https://doi.org/10.33137/cpoj.v7i2.44450 canadian prosthetics & orthotics journal issn: 2561-987x the need for prosthetic guidelines in south africa's private healthcare theron b and visagie s, 2024 reimbursement calculation for professional fees and prosthetic components should also be further explored. acknowledgements thank you to all key informants from the industry willing to share their knowledge and experiences; prosthetists who assisted in the recruitment of lower limb prosthetic users and lastly, the prosthetic users themselves for sharing their stories about their journey as a prosthetic user. declaration of conflicting interests • bennie theron: employee of ossur south africa. • surona visagie: none. authors contribution • bennie theron: research design; conceptualizing of the study; data collection; analysis and interpretation of the data; first draft of the manuscript; manuscript finalization. • surona visagie: research design; conceptualizing of the study; analysis and interpretation of the data; feedback on drafts of the manuscript. sources of support none. references 1.buetow sa, martínez-martín p, mccormack b. ultrabilitation: beyond recovery-oriented rehabilitation. disabil rehabil. 2019; 41(6):740-745. doi: 10.1080/09638288.2017.1406997 2.wyss d, lindsay s, cleghorn wl, andrysek j. priorities in lower limb prosthetic service delivery based on an international survey of prosthetists in low-and high-income countries. prosthet orthot int. 2015; 39(2):102-11. doi: 10.1177/0309364613513824 3.statistical release p0301.4 [internet]. census 2022, statistic south africa. 2023; [cited 2024 dec 11]. available from: https://census.statssa.gov.za/assets/documents/2022/p03014_ce nsus_2022_statistical_release.pdf 4.manickum p, ramklass ss, madiba te. a five-year audit of lower limb amputations below the knee and rehabilitation outcomes: the durban experience. jemdsa. 2019; 24(2):41-5. doi: 10.1080/16089677.2018.1553378 5.fisher k, hanspal rs, marks l. return to work after lower limb amputation. int j rehabil res. 2003; 26(1):51-6. doi: 10.1097/00004356-200303000-00007 6.donaghy ac, morgan sj, kaufman ge, morgenroth dc. team 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https://www.gov.za/sites/default/files/gcis_document/201409/act5 6of1996.pdf 20.compensation for occupational injuries and diseases act 130 of 1993 [internet]. government of south africa. 1993; [cited 2024 dec 11]. available from: https://www.gov.za/sites/default/files/gcis_document/201409/act1 30of1993.pdf 21.compensation for occupational injuries and diseases act 61 of 1997 [internet]. government of south africa.1997; https://doi.org/10.33137/cpoj.v7i2.44450 https://census.statssa.gov.za/assets/documents/2022/p03014_census_2022_statistical_release.pdf https://census.statssa.gov.za/assets/documents/2022/p03014_census_2022_statistical_release.pdf https://www.rand.org/pubs/research_reports/rr2096.html https://www.coidlink.co.za/downloads/tariffs/2024/orthotics%20and%20prosthetics.pdf https://www.coidlink.co.za/downloads/tariffs/2024/orthotics%20and%20prosthetics.pdf https://www.gov.za/sites/default/files/gcis_document/201409/act56of1996.pdf 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from: https://www.gov.za/sites/default/files/gcis_document/201409/a131 -98.pdf 23.medical schemes act 131 of 1998 [internet]. government of south africa. government of south africa. 2004; [cited 2024 dec 11]. available from: https://www.medicalschemes.com/files/acts%20and%20regulatio ns/msregs19july2004.pdf 24.what are prescribed minimum benefits [internet]. council of medical schemes. 2021; [cited 2024 dec 11]. available from: https://www.medicalschemes.co.za/resources/pmb/ 25.cmscript 2-2023 amputations [internet]. council of medical schemes. 2023; [cited 2024 dec 11]. available from: https://www.medicalschemes.co.za/wpfd_file/cmscript-2-2023amputations/ 26.etikan i, musa sa, alkassim rs. comparison of convenience sampling and purposive sampling. am j theor appl stat. 2016;5(1):1-4. doi: 10.11648/j.ajtas.20160501.11 27.appraisal of guidelines for research and evaluation ii [internet]. agree next steps consortium. 2017; [cited 2024 dec 11]. available from: https://www.agreetrust.org/wpcontent/uploads/2017/12/agree-ii-users-manual-and-23-iteminstrument-2009-update-2017.pdf 28.yan j, min j, zhou b. diagnosis of pheochromocytoma: a clinical practice guideline appraisal using agree ii instrument. j eval clin pract. 2013;19(4):626-32. doi: 10.1111/j.13652753.2012.01873.x 29.brouwers mc, kho me, browman gp, burgers js, cluzeau f, feder g, et al. development of the agree ii, part 2: assessment of validity of items and tools to support application. cmaj. 2010;182(10):e472-8. doi: 10.1503/cmaj.091716 30.nowell ls, norris jm, white de, moules nj. thematic analysis: striving to meet the trustworthiness criteria. int j qual methods. 2017;16:1-13. doi: 10.1177/1609406917733847 31.theron bj. an exploration of the need for lower limb prosthetic protocols in the south african private healthcare sector [thesis]. stellenbosch: stellenbosch university. 2024. available from: https://scholar.sun.ac.za/items/af0fbe14-0e14-49f4-bb213962fd4f951a 32.fard b, persoon s, jutte pc, daemen jwhc, lamprou daa, hoope wt, et al. amputation and prosthetics of the lower extremity: the 2020 dutch evidence-based multidisciplinary guideline. prosthet orthot int. 2023;47(1):69-80. doi: 10.1097/pxr. 0000000000000170 33.mcdonald cl, kahn a, hafner bj, morgan sj. prevalence of secondary prosthesis use in lower limb prosthesis users. disabil rehabil. 2023;1-7. doi: 10.1080/09638288.2023.2182919 34.handy eone d, nseme etouckey e, essi mj, ngo nyemb tm, ngo nonga b, ibrahima f. satisfaction of patients with amputated lower limb wearing external prostheses. int j orthop sci. 2018;4(1f):368-72. doi:10.22271/ortho.2018.v4.i1f.52 35.hebert js, burger h. return to work following major limb loss. in: schultz iz, gatchel rj, editors. handbook of return to work: from research to practice. boston, ma: springer us. 2016;505-517 36.griffet j. amputation and prosthesis fitting in paediatric patients. orthop traumatol surg res. 2016;102(1):s161-75. doi: 10.1016/j.otsr.2015.03.020 37.schaffalitzky e, gallagher p, maclachlan m, wegener st. developing consensus on important factors associated with lower limb prosthetic prescription and use. disabil rehabil. 2012;34(24):2085-94. doi: 10.3109/09638288.2012.671885 https://doi.org/10.33137/cpoj.v7i2.44450 https://www.gov.za/sites/default/files/gcis_document/201409/a61-97.pdf https://www.gov.za/sites/default/files/gcis_document/201409/a61-97.pdf https://www.gov.za/sites/default/files/gcis_document/201409/a131-98.pdf https://www.gov.za/sites/default/files/gcis_document/201409/a131-98.pdf https://www.medicalschemes.com/files/acts%20and%20regulations/msregs19july2004.pdf https://www.medicalschemes.com/files/acts%20and%20regulations/msregs19july2004.pdf https://www.medicalschemes.co.za/resources/pmb/ https://www.medicalschemes.co.za/wpfd_file/cmscript-2-2023-amputations/ https://www.medicalschemes.co.za/wpfd_file/cmscript-2-2023-amputations/ https://www.agreetrust.org/wp-content/uploads/2017/12/agree-ii-users-manual-and-23-item-instrument-2009-update-2017.pdf https://www.agreetrust.org/wp-content/uploads/2017/12/agree-ii-users-manual-and-23-item-instrument-2009-update-2017.pdf https://www.agreetrust.org/wp-content/uploads/2017/12/agree-ii-users-manual-and-23-item-instrument-2009-update-2017.pdf https://scholar.sun.ac.za/items/af0fbe14-0e14-49f4-bb21-3962fd4f951a https://scholar.sun.ac.za/items/af0fbe14-0e14-49f4-bb21-3962fd4f951a all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 2 2025 research article bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i2.45823 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 research article health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees bosman c.e.1*, van der sluis c.k.1, vrieling a.h.1, geertzen j.h.b.1, seves b.l.1, groen h.2 1. department of rehabilitation medicine, university of groningen, university medical center groningen, groningen, the netherlands. 2. department of epidemiology, university of groningen, university medical center groningen, groningen, the netherlands. introduction a lower limb amputation (lla) can negatively impact daily activities, participation, and other aspects of life.1-3 individuals with a transfemoral amputation or kneedisarticulation can use a prosthesis with a knee unit. prostheses for persons with a transfemoral amputation or knee disarticulation feature knee units, which are typically classified as non-microprocessor controlled (mechanical) knees (nmpk) or microprocessor controlled knees (mpk). nmpks may be purely mechanical or can include pneumatic or hydraulic systems to assist in swing and/or stance phase control. mpks, equipped with sensors and a microprocessor, can automatically adjust to the user's movements during swing and stance phases. the higher acquisition cost of the mpk is due to not only the inclusion of more advanced and expensive electronic components, but also research and development expenses, as well as testing and regulatory compliance requirements. nevertheless, research suggests that the mpk may offer added value for both active individuals, due to their adaptive capabilities,4 and older users, for whom safety and stability are particularly beneficial.5 despite these potential benefits of the mpk, such as reduced stumbles and falls,6-10 and improvements in walking speed, satisfaction, confidence and quality of life (qol),6,8,9,11-13 it is unclear whether these benefits justify the additional expense. in the netherlands, approximately 10,000 people use a lower limb prosthesis (llp),14 with an estimated one-third having a transfemoral amputation or knee disarticulation.15 over the past decade, annual healthcare costs for llps have increased by over 30%, from €30.4 million in 2012 to * corresponding author: charlotte e. bosman, affiliation: department of rehabilitation medicine, university of groningen, university medical center groningen, groningen, the netherlands. e-mail: c.e.bosman@umcg.nl orcid id: https://orcid.org/0000-0001-7950-5893 open access abstract background: use of a microprocessor-controlled knee (mpk) compared to a non-microprocessorcontrolled knee (nmpk) can lead to improved walking ability, confidence and satisfaction. however, the mpk is more expensive than the nmpk and it is unknown whether the higher costs outweigh the potential benefits. objective: to evaluate the cost-utility and cost-effectiveness of mpks and nmpks from a societal perspective in the netherlands. methodology: participants completed the dutch version of the euroqol five dimensions five levels (eq5d-5l) to assess health-related quality of life, three subscales (ambulation, utility and well-being) of the prosthesis evaluation questionnaire (peq) to assess prosthesis-related quality of life and a cost-questionnaire from societal perspective. incremental cost-utility ratio (icur) and incremental cost-effectiveness ratio (icer) were calculated and the icur was compared with the dutch willingness-to-pay threshold. bootstrapping was used to estimate statistical uncertainty, and multiple imputation was applied to account for missing values. findings: in total, 111 participants were included (37 female, 73 male, 1 unknown; 71 transfemoral, 39 knee disarticulation, 1 unknown; age 64 ± 13 years; 49 nmpk users, 62 mpk users). the cost-utility analysis demonstrated that the mpk yielded an increase of 0.032 quality adjusted life years (qaly) but at considerably higher costs. the mean cost difference was € 14,626, resulting in a mean icur of € 457,063 per qaly gained. the cost difference was mainly driven by acquisition costs but was partially compensated by lower costs of work absence, health care consumption and household care. conclusion: the cost-effectiveness analyses demonstrated that the mpk is likely to provide benefits in term of prosthesis-specific quality of life, but at higher costs. however, short-term (6 months) improvement in healthrelated quality of life was too small to result in substantial qaly gain to offset the higher costs of the mpk and result in an incremental cost-utility ratio below the generally accepted willingness-to-pay thresholds. article info received: august 7, 2025 accepted: october 14, 2025 published: october 30, 2025 citation bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and nonmicroprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8 i2.45823 keywords lower limb; amputation; prostheses; cost analysis; quality of life; questionnaire; mobility; microprocessor knee; cost-effectiveness; knee disarticulation; transfemoral. journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 2, article no. 3. 2025 https://doi.org/10.33137/cpoj.v8i2.45823 https://orcid.org/0000-0001-7950-5893 https://doi.org/10.33137/cpoj.v8i2.45823 https://doi.org/10.33137/cpoj.v8i2.45823 https://jps.library.utoronto.ca/index.php/cpoj/index 2 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 €42.5 million in 2019*, with per-user costs rising from €3,110 to €4,400.14 the relationship between these cost increases and mpk prescriptions has not been studied. besides the prosthesis acquisition cost, other factors such as visits to healthcare professionals, prosthesis repairs and home environment adjustments must be considered. additionally, mpk use can affect a person’s productivity and ability to contribute to society. to fully understand the costutility and cost-effectiveness of prosthetic knees, a societal perspective that includes all these factors is essential. economic evaluations can be used to inform policy decisions about the allocation of health care funds irrespective of the disease.16 the most commonly used types of economic evaluations are the cost-utility analysis and cost-effectiveness analysis.17 for both the cost-utility analysis and cost-effectiveness analysis, the difference in costs (incremental costs) is divided by the difference in effects (incremental effects), resulting in either an incremental cost utility ratio (icur) or an incremental cost effectiveness ratio (icer).17 in a cost-utility analysis, the effects are expressed in qualityadjusted life years (qalys), and this analysis can therefore be used for broad comparisons. the value of the icur can be compared across different diseases and to the threshold value for willingness-to-pay for one qaly. the costeffectiveness analysis on the other hand, can use prosthesis-related effect measures for a more specific comparison. several studies have performed a cost-utility analysis to compare the mpk to the nmpk, and reported icurs within the willingness-to-pay threshold.18-22 however, icurs varied widely,18,20 likely due to differences in study design and perspectives. variations in healthcare costs and insurance coverage across countries also contribute to this disparity, raising questions about the generalizability in the netherlands. a dutch study by seelen et al.23 compared mpks to nmpks in a cost-consequence design and reported that the average annual costs per person was lower for mpk users compared to nmpk users, but without calculating incremental cost and effect differences. higher mpk acquisition costs were offset by lower costs in other areas, such as housekeeping assistance and productivity loss.23 given that previous economic evaluation studies were conducted outside the netherlands and their results cannot be translated to the dutch healthcare system, we performed an economic evaluation of mpks and nmpks in the netherlands. the objectives of this study were to calculate the incremental cost-utility ratio and incremental costeffectiveness ratio from a societal perspective and assess the relation of the incremental cost-utility ratio to the dutch willingness-to-pay threshold.24 based on previous studies,18-21,25 we hypothesized that the mpk would be costeffective compared to the nmpk. methodology the dutch guideline for the conduct of economic evaluations in healthcare was applied.17 results are presented in accordance with the consolidated health economic evaluation reporting standards (cheers) statement.26 the medical ethics committee of the university medical center groningen (metc 2019/419) provided a waiver for formal approval. research was conducted according to the declaration of helsinki and its amendments. all participants were asked to provide their written informed consent before completing the survey. this study was registered at clinicaltrials.gov: nct06105944. data collection and analyses • participants individuals with a unilateral transfemoral amputation or knee-disarticulation, who were using a prosthesis, were eligible for participation. the inclusion criteria were: (1) at least 18 years old; (2) at least one year post amputation; (3) able to read and write in dutch; (4) using a prosthesis with socket. participants were recruited via two large prosthetic companies with multiple branches in the netherlands. • data collection postal surveys were sent to eligible participants between december 2022 and march 2023. non-respondents received a reminder after 12 weeks. participants received a €10 gift voucher for their participation. study data were collected and managed using redcap electronic data capture tools.27,28 participants who did not meet the inclusion criteria, did not state their prosthetic knee type or did not complete the eq-5d-5l were excluded from analyses. survey development the survey consisted of a questionnaire with four separate sections: 1) patient demographics; 2) costs related to llp use; 3) health-related qol, and 4) prosthesis-related qol. • patient demographics participants provided information on their age, sex, educational level, employment status, the side and level of their limb loss, the type of prosthetic knee they were currently using, and their years of prosthesis experience. *more recent cost data were not available due to inconsistencies in the registration of assistive devices by health insurance companies. as a result, the national health care institute has restricted access to detailed datasets (email correspondence, november 2024). https://doi.org/10.33137/cpoj.v8i2.45823 3 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 • costs related to prosthesis use to assess medical consumption and productivity costs, we combined the imta medical consumption questionnaire (imcq)29 and the imta productivity cost questionnaire (ipcq).30 the imcq measures medical consumption, household assistance, and help from friends and family, while the ipcq evaluates productivity losses, including absenteeism, presenteeism, and unpaid work.31 to tailor the questionnaires to llp users, we replaced questions about dieticians, speech therapists and emergency room visits with questions about prosthesis type and visits to a rehabilitation facility or certified prosthetist/orthotist (cpo). furthermore, we added questions about personal costs for prosthesis acquisition, repairs, home or vehicle adjustments and hobbies. this resulted in a 24-items questionnaire (appendix i). psychometric properties of this questionnaire are not available. while no validity studies have been conducted yet, the majority of the questions within the ipcq were sourced from existing validated questionnaires, with the exception of the section addressing “productivity losses related to unpaid work”31 moreover, the development of the imcq took place in the netherlands, tailoring it to the country’s healthcare system.29 the recall periods of the imcq and ipcq were extended to six months to capture a reliable overview of llp-related costs. the recall period defines the time span participants should reflect on when answering the questionnaire items. direct medical costs, informal care, and travel expenses were derived from the questionnaires, while indirect medical costs related to productivity loss were calculated using the friction cost method with a friction period of 115 days, including the value of unpaid work.17 the friction cost method estimates the economic impact of productivity losses due to illness or premature death by considering only the time required to replace a worker and restore production, rather than the entire period of absence. costs for appointments with healthcare providers were valued at standard dutch prices,32 and costs for an appointment with the cpo were based on average outpatient consultation costs.32 acquisition costs for nmpk and mpk were based on information derived from orthopaedic workshops, and presenteeism and absenteeism were determined according to dutch guidelines.32 • health-related quality of life participants completed the dutch version of the euroqol five dimensions five levels (eq-5d-5l),33,34 a selfassessment tool with five questions on mobility, self-care, daily activities, pain, and anxiety/depression. each question has five response levels, defining a unique health state. the dutch scoring algorithm for the eq-5d-5l was used to compute a single value representing health status. scores can range from -0.466 to 1, with a higher score representing a better qol.35 participants also rated their perceived health on a visual analogue scale (vas) from 0 (worst imaginable health) to 100 (best imaginable health). the eq-5d-5l is a reliable and valid questionnaire,36 with satisfactory measurement properties for patients with major unilateral lla.37 • prosthesis-related quality of life the utility, ambulation and well-being scales of the prosthesis evaluation questionnaire (peq) were used, as they align with eq-5d-5l items. the peq is a reliable and valid self-report tool for evaluating prosthesis-related qol.38 it includes nine scales, as well as several separate questions which can be used independently.39 questions are scored on a vas (0-100), with higher scores indicating more positive outcomes. health economic evaluation two methods are commonly used for an economic evaluation: 1) a cost-utility analysis or 2) a costeffectiveness analysis. in a cost-utility analysis, the effects are expressed in quality-adjusted life years (qalys). qalys are calculated by adjusting life years for a utility measure reflecting quality, ranging from 0 (death) to 1 (full health).16 in this study, the utility score of the eq-5d-5l was multiplied with the six-month measurement period to calculate the qalys. comparing the difference in qalys to the difference in costs, results in the incremental cost-utility ratio (icur), or cost per qaly gained40 (see equations below). the value of this parameter can be compared across different diseases and also to the threshold value for willingness-to-pay for a gain of one qaly. the values of these willingness-to-pay thresholds vary across countries and are linked to the burden of disease (higher burden of disease equals a higher threshold). in contrast, a costeffectiveness analysis uses a clinical effect measure to calculate the incremental cost-effectiveness ratio (icer), representing the additional cost per unit of a specific health outcome, such as improved mobility or prosthesis-related qol (see equation below). unlike the cost-utility analysis, which uses qalys as a generic measure, a costeffectiveness analysis can focus on specific, relevant outcomes for prosthesis users. this allows for a more detailed understanding of how cost differences between prosthetic knees can impact prosthesis users' daily lives. 𝐼𝐶𝑈𝑅 = ∆𝐶𝑜𝑠𝑡 ∆𝑄𝐴𝐿𝑌 (1) 𝐼𝐶𝐸𝑅 = ∆𝐶𝑜𝑠𝑡 ∆𝐸𝑓𝑓𝑒𝑐𝑡 (2) icur: incremental cost utility ratio; icer: incremental cost effectiveness ratio; ∆: difference. the economic evaluation in this study was based on crosssectional data, adopting a societal perspective and including direct medical costs and indirect costs. the icur https://doi.org/10.33137/cpoj.v8i2.45823 4 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 was calculated by dividing the mean cost difference between nmpk and mpk by the mean qaly difference based on the eq-5d-5l. furthermore, three icers were calculated by dividing the mean cost difference by the mean score difference on the peq scales. to estimate statistical uncertainty and robustness of results, we used the bootstrap method to simulate 5000 repetitions of the study, with variations in mean incremental costs and effects.41 bootstrap results are presented as a scatterplot in a cost-effectiveness plane (ce-plane) with incremental effects on the x-axis and incremental costs on the y-axis. the ce-plane is divided into the north-east (ne) quadrant, the north-west (nw) quadrant, the south-west (sw) quadrant and the south-east (se) quadrant. replications in these quadrants represent the following results: ne (better health outcomes, higher cost), nw (worse health outcomes, higher cost), se (better health outcomes, lower cost), and sw (worse health outcomes, lower cost). the bootstrap results were used to construct a cost-effectiveness acceptability curve (ceac) summarizing the probability of cost-effectiveness of the mpk over the nmpk at various willingness-to-pay thresholds for each qaly gained. the value of this threshold depends on the burden of disease (appendix ii table 1a). a specific burden of disease score was not available for lla or prosthesis use and was therefore calculated based on the dutch guidelines24 (appendix ii -table 2a). statistical analyses to address missing data, we applied multiple imputation and bootstrapping. multiple imputation was used to generate several complete datasets by replacing missing values with plausible estimates based on observed data patterns. bootstrapping was then performed on these imputed datasets to assess the stability and variability of the results, providing more reliable statistical inference while accounting for uncertainty introduced by the missing values. missing values for cpo visits and informal care (11 and 3 cases, respectively) were imputed using average numbers. prior to bootstrap replication, missing data for healthcare visits (10 cases) were handled by multiple imputation, adjusted for age, sex, prosthesis type, amputation level, and prosthesis side. the average of 50 imputations was used for the bootstrap procedure. continuous variables were assessed for normality and variance equality using q-q plots, kolmogorov-smirnov f survey sent to llp users (n=642) responses entered into redcap (n = 166) included in hee (n = 111) did not meet inclusion criteria (n = 55) no kd or tfa (n = 8) bilateral limb loss (n = 12) did not use llp (n = 5) osseointegration (n = 16) llp type unknown (n = 2) did not complete all surveys (n = 12) declined (n = 7) declined participation (n = 3) ineligible (n = 4) not possible to contact (n = 19) no up-to-date address information (n = 9) deceased (n = 6) return to sender/unknown (n = 4) no response (n = 450) figure 1: flowchart of survey distribution (blue), response (yellow), and inclusion process (green) for the health economic evaluation (hee). llp: lower limb prosthesis; kd: knee-disarticulation; tfa: transfemoral amputation. https://doi.org/10.33137/cpoj.v8i2.45823 5 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 tests, and levene’s tests. differences in demographics, eq-5d-5l utility and vas scores, peq scale scores, and costs between groups of prosthesis users were evaluated using kruskal-wallis tests, mann-whitney u tests or unpaired t-tests for continuous variables, and a pearson’s χ2 test for categorical variables. all tests were two-tailed with significance set at p<0.05. since none of the continuous variables met the assumptions of a one-way anova, only kruskal-wallis tests were performed, followed by mann-whitney u tests with bonferroni correction (p<0.005). data analyses were conducted using ibm spss statistics version 28 (ibm corporation, armonk, ny, usa) and stata version 18 se (statacorp, college station, tx, usa). results surveys were sent to 642 participants, with 166 responding (response rate 28.5%) (figure 1). forty-one respondents did not meet the inclusion criteria. additionally, the knee type was unknown for two respondents and twelve respondents did not complete all parts of the survey. ultimately, 111 respondents were included (age 64 ± 13 years; table 1). mpk users were significantly younger and the time since amputation was significantly lower compared to nmpk users. furthermore, we found significant differences in whether participants were using their first prosthesis and if they had obtained a new prosthesis within the last six months, with the nmpk group scoring higher in both scenarios. costs related to prosthesis all cost components, including visits to healthcare professionals, prosthesis acquisition, and productivity losses, were valued using dutch standard pricing and data obtained from orthopaedic workshops and national guidelines (table 2). mean medical and non-medical costs mean medical and non-medical costs were categorized into six groups: hospital admission, cpo visits, visits to other healthcare professionals (hcp), productivity loss, other costs, and total costs. no significant differences in mean costs between groups were demonstrated in hospital admission, cpo visits, visits to other hcps, combined costs for visits to hcps and productivity loss (table 3). in ‘other costs’, significantly higher costs for household care (p = 0.016) were found in the nmpk group compared to the mpk group. however, total costs were significantly higher for the mpk group (p < 0.001) mainly due to higher acquisition costs (table 3). more detailed information is shown in appendix iii table a3. outcome measures a significant difference in the peq ambulation scale was observed between the nmpk and mpk. no significant differences were found on the remaining peq scales, as well as the eq-5d-5l utility score and vas score (table 4). table 1: demographic characteristics of 111 participants categorized by type of prosthetic knee. nmpk (n = 49) mpk (n = 62) p-value age, (mean ± sd) 67 ± 12 62 ± 14 0.027* sex, n (%)a 0.953† • female 16 (33) 21 (34) • male 32 (65) 41 (66) side of lla, n (%)a 0.063 • left 17 (35) 33 (53) • right 31 (63) 29 (47) level of lla, n (%)a 0.417 • transfemoral 33 (67) 38 (61) • knee-disarticulation 15 (31) 24 (39) employment status, n (%)a 0.246 • wage employment 5 (10) 15 (24) • self-employed 6 (12) 7 (11) • homemaker 6 (12) 5 (8) • unemployed 1 (2) 0 • incapacity to work 4 (8) 9 (15) • retired 27 (55) 26 (42) years since amputation, (mean ± sd) 28 ± 24 16 ± 18 0.005* level of educationa,b 0.324 • low 21 (43) 18 (29) • middle 15 (30) 25 (40) • high 13 (27) 18 (29) new prosthesis in last 6 months, yes n (%) 10 (20) 10 (16) 0.029* first prosthesis, yes n (%) 13 (27) 3 (5) 0.001* nmpk: non-microprocessor-controlled knee; mpk: microprocessorcontrolled knee; sd: standard deviation; lla: lower limb amputation asome variables have missing responses and therefore do not add up to 100% blow: no education or lower vocational education; middle: middle vocational education; high: higher education such as university of applied sciences or university (bsc/msc) *significant at α < 0.05. †this p-value indicates that there was no significant difference in the gender distribution between the two groups. cost-utility analysis the mean cost difference after bootstrap was €14,626, with lower costs for the nmpk, and the mean qaly difference was 0.032 in favor of the mpk. this resulted in a mean incremental cost-utility ratio (icur) of €457,063 per qaly gained (table 5). most bootstrap replications fell within the ne quadrant (figure 2, left panel), indicating higher utility and higher costs for the mpk compared to the nmpk. the cost-effectiveness acceptability curve in figure 2 (right panel) demonstrates that the probability of the mpk being cost-effective does not exceed that of the nmpk until well over €400,000 per qaly, far above all willingness-to-pay thresholds (€20,000; €50,000 and €80,000).24 https://doi.org/10.33137/cpoj.v8i2.45823 6 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 table 2: unit costs used in calculations. unit price/distance source/remark hospital admission €644.00 guideline, no distinction general/university hospital outpatient visits dutch guidelines • cpo €120.00 guideline average price outpatient visit • rehabilitation €120.00 guideline average price outpatient visit visits healthcare professionals • general practitioner €30.87 guideline, per visit • physiotherapist €38.89 guideline, per visit • occupational therapist €24.32 guideline, per visit • social worker €127.00 guideline, per visit • psychologist/psychiatrist €109.80 guideline, average primary care and private • occupational health physician €200.00 average price occupational health and safety service household support and informal care • household help €32.76 guideline, per hour • personal care €57.58 guideline, per hour • nursing care €75.00 guideline, per hour • informal care €18.80 guideline, per hour out of pocket costs real costs guideline paid work • friction period (days) 115 guideline, average past 5 years • friction period (weeks) 16.4 guideline, average past 5 years • productivity cost/hour €39.88 average for male and female, per hour travel costs dutch guidelines • car €0.26 euro/km, parking costs € 3.00 per visit • public transport €0.21 euro/km • taxi €2.47 euro/km, start costs € 3.36 per ride • unknown €0.26 euro/km, car price applied average travel distances • general practitioner 1.1 km guideline • physiotherapist 2.2 km guideline • occupational therapist 2.2 km assumed same as physiotherapist • social worker 7.0 km assumed same as hospital • psychologist/psychiatrist 7.0 km assumed same as hospital • occupational health physician 3.7 km average travel distance home to work • hospital 7.0 km guideline prosthetic knee costs • mpk €21,018 expert opinion • nmpk €4,417 expert opinion cost-effectiveness analysis the mean score for the peq-ambulation scale after bootstrap was 14.6 points higher for the mpk group compared to the nmpk group, resulting in a mean incremental cost-effectiveness ratio (icer) of €1,020 per point gained (table 5). nearly all bootstrap replications fell within the ne quadrant, indicating higher self-reported walking ability and higher costs for the mpk compared to the nmpk (figure 3-top). furthermore, 78.1% of bootstrap replications exceeded the minimal detectable change (mdc) of 11 points.42 after the bootstrap, the mean score for the peq-utility scale was 5.4 points higher for the mpk group compared to the nmpk group, yielding a mean icer of €2,757 per point gained (table 5). most bootstrap replications fell within the ne quadrant, indicating higher utility and higher costs for the mpk compared to the nmpk (figure 3-middle). of all the bootstrap replications, 2.2% exceeded the mdc of 12 points.42 lastly, a mean score difference of 4.5 points higher for the mpk group compared to the nmpk group was found on the peq-well-being scale after bootstrapping, resulting in a mean icer of €3,308 per point gained (table 5). the majority of the bootstrap replications fell within the ne quadrant, indicating better reported well-being and higher costs for the mpk compared to the nmpk (figure 3-bottom). half a percent of the bootstrap replications exceeded the mdc of 14.42 discussion this study demonstrates that the mpk is likely to provide higher scores of prosthesis-related and health-related qol to its users compared to the nmpk, but at higher societal costs. the cost-effectiveness analyses yielded reasonable icers for prosthesis-related qol ranging from €1,020 to €3,308, indicating that the costs to achieve a minimally detectable change is very reasonable and well within the willingness-to-pay threshold. however, based on the icur for health-related qol, the mpk was determined not to be cost-effective. it is important to note that both the icur and icer were based on short term measurements and as was shown in previous studies18,20,21 the icur will most likely be lower, making the mpk more cost-effective over a longer period of time. the significantly higher costs for the mpk were mostly driven by the higher acquisition costs, while the combined costs for visits to healthcare professionals were lower for this group compared to the nmpk group. as was shown in a previous study, the higher acquisition costs for the mpk will be balanced out after 19 months due to the lower healthcare costs related to falls.43 for clinicians and policy makers, this would mean that the higher initial costs are an investment that will lead to lower long-term costs and significant functional improvements for the prosthesis users. https://doi.org/10.33137/cpoj.v8i2.45823 7 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 table 3: mean costs (in euros) by category and type of prosthetic knee. nmpk (n = 42) # mpk (n = 55) p-value hospital admission • direct costs 184 (0, 0-7728) 46 (0, 0-1932) 0.754 outpatient visits • cpo 357 (142, 0-2148) 302 (249, 0-1351) 0.491 other hcp visits • general practitioner 290 (0, 0-10605) 38 (0, 0-331) 0.921 • physiotherapist 130 (0, 0-1381) 335 (0, 0-2298) 0.106 • occupational therapist 4 (0, 0-84) 3 (0, 0-140) 0.887 • social worker 6 (0, 0-268) 12 (0, 0-669) 0.849 • psychologist/psychiatrist 3 (0, 0-117) 26 (0, 0-886) 0.445 • occupational health physician 24 (0, 0-817) 4 (0, 0-206) 0.400 • combined hcp visit costs 458 (17, 0-10988) 418 (0, 0-2419) 0.081 other costs • out of pocket costs 1094 (0, 0-20000) 1420 (0, 0-43000) 0.678 • household care 1678 (0, 0-25657) 270 (0, 0-3407) 0.016* • informal care 822 (0, 0-13686) 1190 (0, 0-17597) 0.473 productivity loss • friction costs 368 (0, 0-15442) 161 (0, 0-4786) 0.483 • presenteeism 21 (0, 0-383) 101 (0, 0-3988) 0.769 total costs • prosthesis (fixed) 4417 21018 na • total costs, excluding prosthesis 4981 (1308; 0-39340) 3909 (1376; 0-43108) 0.730 • total costs, including prosthesis 9395 (5725, 4417-43757) 24927 (22394, 21018-64126) <0.001* data presented as mean (median, min-max). significance was tested using the mann whitney u test. nmpk: non-microprocessor controlled knee; mpk: microprocessor controlled knee; cpo: certified prosthetist/orthotist; na: not applicable. * significant at α < 0.05. # in tables presenting statistical results, the number of participants depends on the available complete data. table 4: scores eq-5d-5l and peq. nmpk (n = 49) mpk (n = 60)* mean difference p-value eq-5d-5l utility 0.742 0.787 0.045 (-0.028 to 0.118) 0.225 eq-5d-5l vas 73.5 78.3 4.78 (-3.58 to 13.1) 0.259 peq-am 52.0 67.0 15.0 (–6.0 to 24.0) 0.001 peq-ut 69.2 74.0 4.8 (-1.8 to 11.5) 0.154 peq-wb 72.8 76.3 3.4 (-4.7 to 11.5) 0.402 vas: visual analogue scale; peq-am: prosthesis evaluation questionnaire ambulation scale; peq-ut: prosthesis evaluation questionnaire utility scale; peq-wb: prosthesis evaluation questionnaire well-being scale; * n=58 for eq-5d-5l table 5: icur and icer calculation. nmpk (n = 46) mpk (n = 55)* p-value mean difference† icur/icer‡ qaly 0.37 0.40 0.08 0.03 (-0.04 to 0.09) 457,063 peq-am 53.3 67.9 0.002 14.6 (1.1 to 30.5) 1,020 peq-ut 69.4 74.9 0.11 5.4 (-7.7 to 16.7) 2,757 peq-wb 72.8 77.4 0.27 4.5 (-10.7 to 18.5) 3,308 icur: incremental cost-utility ratio; icer: incremental cost-effectiveness ratio; na: not applicable; peq: prosthesis evaluation questionnaire; am: ambulation; ut: utility; wb: well being; * n=52 for qaly; † mean difference after bootstrap; ‡ icur/icer calculated with mean cost difference of €14,626 after bootstrap; icur/icer were calculated based on population that completed the peq/eq5d and had costs. https://doi.org/10.33137/cpoj.v8i2.45823 8 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 mean costs and medical consumption the significant difference in total costs between mpk and nmpk was mainly driven by the fixed high acquisition costs of mpk (€21,018) compared to nmpk (€4,417). this is similar to previous studies.18,20,22 however, a recent study demonstrated that while the mpk’s acquisition costs exceeded those of the nmpk, this would offset after 19 months due to lowered healthcare costs related to falls.43 when excluding the acquisition costs, total costs were higher for nmpk (table 3). higher costs for the nmpk group were related to higher combined costs for visits to hcps and higher costs for household care. while this study did not investigate the specific causes for visits to hcps, one study demonstrated that the medical costs for fall-related incidents were 2.67 times higher for nmpk users compared to mpk users, which made up 46% of the total costs for this group.22 previous studies have demonstrated that the use of an mpk can result in a significant decrease in falls compared to an nmpk, which could substantiate the findings4,6,8,10,13,44 therefore, it would be valuable for future research to examine the specific fall-related costs in more detail, as this could provide further insight into the economic impact of the mpk compared to the nmpk. furthermore, mpk users demonstrated higher presenteeism and lower friction costs. these findings support earlier studies reporting decreased household costs and less productivity loss with mpk compared to the nmpk.23 recently, a dutch study demonstrated significant improvements in participation with mpk use compared to nmpk,10 which could explain the reduced need for household care and lower work absence. outcome measures the mpk group showed significantly higher scores on the peq ambulation scale compared to the nmpk group. this aligns with other studies reporting significant improvements in walking ability with mpk, including walking distance, speed, and terrain navigation,11,45 as well as self-reported walking ability.4,45 no significant differences were found on both the utility score and vas score of the eq-5d-5l between the mpk and nmpk, which contrasts earlier findings.20,21 additionally, no significant differences were found in the utility and well-being scales of the peq, which contradicts previous studies that reported significantly higher scores on these scales for mpk users.10,12,45,46 the disparity could stem from methodological differences, since participants in this study were assessed using their own prosthesis without an intervention, preventing direct comparison between the mpk and nmpk. participants in both groups may have been generally content with their current prostheses, resulting in no significant differences. cost-utility analysis based on the icur, the mpk was not cost-effective compared to nmpk. most bootstrap replications indicated improved qol with mpk, but costs were higher, exceeding all willingness-to-pay thresholds. our mean icur was €457,063 per qaly gained, more than ten times higher than other studies, which reported icurs ranging from €3,21815 to €40,155.20 one study stratified participants into three groups based on age at enrolment; age at first prosthesis; and years of experience using a prosthesis, figure 2: left panel: cost-effectiveness plane (ce-plane) showing the distribution of bootstrap replications for the differences between costs and effects of the mpk versus the nmpk. blue dots indicate how many of the 5000 replications fall in the respective quadrants. the ceplane is divided into the north-east (ne) quadrant, the north-west (nw) quadrant, the south-west (sw) quadrant and the south-east (se) quadrant. replications in these quadrants represent the following results: ne (better health outcomes, higher cost), nw (worse health outcomes, higher cost), se (better health outcomes, lower cost), and sw (worse health outcomes, lower cost). right panel: costeffectiveness acceptability curve (ceac) showing the probability of cost-effectiveness of the mpk and nmpk at increasing values of the ceiling ratio for willingness-to-pay for a qaly gained. mean incremental qaly 6 months values of ceiling ratio m e a n i n c re m e n ta l c o s t 6 m o n th s probability mpk cost-effective probability nmpk cost-effective https://doi.org/10.33137/cpoj.v8i2.45823 9 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 yielding icurs between €28,269 and €88,779,20 but even the highest icur was much lower than ours. mean incremental cost differences in other studies ranged from €7,657 to €18,431,18,20,21 comparable to our €14,626. figure 3: cost-effectiveness planes (ce-planes) showing the distribution of bootstrap replications for the differences between costs and effects of the mpk versus the nmpk on the peq ambulation scale (top panel); peq utility scale (middle panel); peq well-being scale (bottom panel). mdc: minimal detectable change. the ce-plane is divided into the north-east (ne) quadrant, the north-west (nw) quadrant, the south-west (sw) quadrant and the south-east (se) quadrant. replications in these quadrants represent the following results: ne (better health outcomes, higher cost), nw (worse health outcomes, higher cost), se (better health outcomes, lower cost), and sw (worse health outcomes, lower cost). mean incremental peq-am score m e a n i n c re m e n ta l c o s t 6 m o n th s m e a n i n c re m e n ta l c o s t 6 m o n th s m e a n i n c re m e n ta l c o s t 6 m o n th s mean incremental peq-ut score mean incremental peq-wb score https://doi.org/10.33137/cpoj.v8i2.45823 10 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 however, qalys gained with the mpk in other studies were much higher (0.42 – 2.38) than our finding of 0.032.18,20-22 methodological differences likely explain the variance in results. firstly, the six-month timeframe in this study contrasts with other studies' 5-year,20,21 8-year18 or even 25year22 periods. longer follow-up with sustained improvement of qol with the mpk is likely to result in larger qol differences compared to the nmpk. simultaneously, higher acquisition costs of the mpk could be compensated by lower healthcare consumption if measured over a longer period of time. furthermore, not all studies included the same costs. our study included acquisition, direct, and indirect medical costs and productivity loss, whereas other studies limited costs to acquisition and maintenance,18 did not specify costs for hcps other than the general practitioner,21 or analyzed acquisition, maintenance, and transportation costs but did not specify them.20 the lack of specific cost insights in other studies prevents direct comparison to further clarify the icur difference. cost-effectiveness analysis the icers based on prosthesis-related outcomes indicated that the mpk could result in better qol at acceptable costs per unit of improvement compared to the nmpk. however, formal thresholds for acceptability of these cost differences for a unit of improvement are not available, so this remains arbitrary. although a direct comparison with a formal threshold is not possible, it is worth noting that due to the fairly low icers, the costs associated with achieving the mdcs for each peq scale can be considered reasonably priced. e.g. the costs to achieve the mdc of 11 points for the peq ambulation scale would cost €11,215. in this study, we demonstrated a significant difference in score on the peq-ambulation scale, which exceeded the mdc in 78.1% of the bootstrap replications. this is comparable to previous studies that investigated the differences in walking ability between the mpk and nmpk4,12,21,45,47 while we did not find significant differences in the other peq-scales, other studies using intervention designs with a within-subject comparison did report significant differences on these scales.10,12,45,46 this design difference may explain the variation in outcomes. limitations this study had several limitations. firstly, we only considered the cost of the prosthetic knee unit, excluding other parts of the prosthesis such as the socket, pylon and foot, which may result in an underestimation of the total cost. moreover, we were unable to obtain prosthesis costs at the individual level, leading to absence of variation in prosthesis cost as a major component of total costs. additionally, prosthesis users differed between those using an nmpk or an mpk, with variations in age, activity level, and health status potentially influencing the outcomes and generalizability of the findings. lastly, our non-intervention design did not allow for direct comparison between the nmpk and mpk. conclusion the cost-effectiveness analyses demonstrated that the mpk is likely to improve prosthesis-specific qol, but at higher costs. however, short-term (6 months) improvement in health-related qol was too small to result in substantial qaly gain to offset the higher costs of the mpk and result in an incremental cost-utility ratio below the generally accepted willingness-to-pay thresholds. acknowledgements the authors would like to express their sincere gratitude to oim orthopedie and livit orthopedie for their support in participant recruitment and survey distribution. furthermore, we would like to thank all participants for their time and valuable contributions to this study. declaration of conflicting interests the authors declare no conflicts of interest. the funders had no role in the design of the study; in the collection, analyses or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. authors’ contribution • charlotte e. bosman: conceptualization, methodology, formal analysis, investigation, data curation, writing original draft, review & editing, visualization, project administration. • corry k. van der sluis: conceptualization, methodology, review & editing, funding acquisition. • aline h. vrieling: conceptualization, methodology, review & editing, funding acquisition. • jan h.b. geertzen: review & editing, funding acquisition. • bregje l. seves: methodology, review & editing. • henk groen: conceptualization, methodology, formal analysis, data curation, review & editing, visualization. all authors read and approved the final manuscript. sources of support this study was funded by zonmw as part of a larger research project entitled ‘effectiveness and cost-effectiveness of lower limb prostheses’ (project number: 853001109; url: https://projecten.zonmw.nl/nl/project/doelmatige-zorg-vanbeenprothesen). references 1.couture m, caron cd, desrosiers j. leisure activities following a lower limb amputation. disabil rehabil. 2010; 32(1): p. 57–64. https://doi.org/10.3109/09638280902998797 https://doi.org/10.33137/cpoj.v8i2.45823 https://projecten.zonmw.nl/nl/project/doelmatige-zorg-van-beenprothesen https://projecten.zonmw.nl/nl/project/doelmatige-zorg-van-beenprothesen https://doi.org/10.3109/09638280902998797 11 bosman c.e, van der sluis c.k, vrieling a.h, geertzen 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norms for the eq-5d-5l, 2018. qual life res. 2022;31(2):527–37. https://doi.org/10.1007/s11136-021-02971-6 53.jensen mb, jensen ce, gudex c, pedersen km, sørensen ss, ehlers lh. danish population health measured by the eq-5d-5l. scand j public health. 2023;51(2):241–9. https://doi.org/10.1177/14034948211058060 54.poder tg, carrier n, kouakou crc. quebec health-related quality-of-life population norms using the eq-5d-5l: decomposition by sociodemographic data and health problems. value health. 2020;23(2):251–9. https://doi.org/10.1016/j.jval.2019.08.008 https://doi.org/10.33137/cpoj.v8i2.45823 https://www.cbs.nl/nl-nl/nieuws/2018/44/prognose-levensverwachting-65-jarigen https://www.cbs.nl/nl-nl/nieuws/2018/44/prognose-levensverwachting-65-jarigen https://www.hartenvaatcijfers.nl/jaarcijfers/basiscijfers-perifeer-arterieel-vaatlijden-d62a3#:~:text=in%202022%20vonden%20er%202.525,opnamen%20per%20dag%20voor%20vrouwen https://www.hartenvaatcijfers.nl/jaarcijfers/basiscijfers-perifeer-arterieel-vaatlijden-d62a3#:~:text=in%202022%20vonden%20er%202.525,opnamen%20per%20dag%20voor%20vrouwen https://www.hartenvaatcijfers.nl/jaarcijfers/basiscijfers-perifeer-arterieel-vaatlijden-d62a3#:~:text=in%202022%20vonden%20er%202.525,opnamen%20per%20dag%20voor%20vrouwen https://www.hartenvaatcijfers.nl/jaarcijfers/basiscijfers-perifeer-arterieel-vaatlijden-d62a3#:~:text=in%202022%20vonden%20er%202.525,opnamen%20per%20dag%20voor%20vrouwen https://doi.org/10.1186/s12955-021-01719-7 https://doi.org/10.1007/s11136-021-02971-6 https://doi.org/10.1177/14034948211058060 https://doi.org/10.1016/j.jval.2019.08.008 14 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 appendices appendix i – english translation of the cost-questionnaire question 1. what was your occupation during the past 6 months? ................................................................................................................................... question 2. how many hours per week did you work during the past 6 months? only count the hours for which you were paid. ………… hours question 3. how many days per week did you work during the past 6 months? ………… days question 4. have you been absent from work due to illness during the past 6 months? this refers to absence or sick leave related to your prosthesis or amputation.  no  yes, i was unable to work for the entire 6 months  yes, i was absent for approximately ….. days (only count the working days in the past 6 months) if you checked ‘’yes,’’ please answer question 5. otherwise, continue with question 7. question 5. were you absent from work for more than 4 consecutive weeks due to illness during the past 6 monts?  no  yes if you checked ‘’yes,’’ please answer question 6. otherwise, continue with question 7. question 6. how long were you ill for? this refers to absence or sick leave related to your prosthesis or amputation. approximately …… weeks question 7. were there days during the past 6 months when you worked but experienced physical or psychological problems during work? this refers to complaints related to your prosthesis or amputation.  no  yes if you checked ‘’yes,’’ please answer question 8 and 9. otherwise, continue with question 10. please read the explanation above question 10 first. question 8. on how many working days did you experience physical of psychological problems during work? only count the working days in the past 6 months. approximately …… working days question 9. on the days you experienced problems, you may not have been able to work as much as usual. how much work could you do on those days on average? refer to the scale below. 10 means you could work as much as usual. 0 means you could do nothing. circle the appropriate number. i could do nothing on those days i could do about half i could do as much as usual 0 1 2 3 4 5 6 7 8 9 10 the following questions are about your job. that means work for which you are paid. the questions refer to the job you held during the past 6 months. if you do not have a paid job, please continue with question 10. be sure to read the explanation above question 10 first. https://doi.org/10.33137/cpoj.v8i2.45823 15 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 question 10. were there days during the past 6 months when you could do less unpaid work due to physical or psychological problems? this refers to problems related to your prosthesis use during the past 6 months.  no  yes if you checked ‘’yes,’’ please answer question 11. otherwise, continue with question 12. question 11. on how many days did this occur? only count the days in the past 6 months …… days question 12. have you been admitted to a rehabilitation center during the past 6 months?  no admission  ….. days of admission question 13. how many appointments did you have with your general practitioner or practice nurse during the past 6 months?  no appointments  ….. appointments question 14. how many appointments did you have with a social worker during the past 6 months?  no appointments  ….. appointments explanation for question 10 and 11: unpaid work you may also experience physical or psychological problems with unpaid work. sometimes this means you can do less. for example, you may struggle to care for your children, do volunteer work, go grocery shopping, or work in the garden. the following questions are about this. ook bij onbetaald werk kunt u last hebben van uw lichamelijke of psychische problemen. soms kunt u daardoor minder doen. u kunt bijvoorbeeld niet goed voor de kinderen zorgen of vrijwilligerswerk doen. of geen boodschappen doen of in de tuin werken. daarover gaan de volgende vragen. explanation we would like to know which doctors you had appointments with during the past 6 months. these should be appointments for yourself. other healthcare providers also count. for example, appointments with a physical therapist or cpo/prosthetist. which appointments count? • check-ups • appointments due to physical or psychological complaints • home visits by a doctor • telephone appointments • calls to the prescription line what appointments do not count? • appointments for someone else, such as your partner or child • calls to schedule an appointment if you’re not sure how many appointments you had, please write down an approximate number. https://doi.org/10.33137/cpoj.v8i2.45823 16 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 question 15. how many appointments did you have with you prosthetist/cpo?  no appointments  ….. appointments question 16. how many appointments did you have with a physical therapist during the past 6 months? or with a caesar therapist, mensendieck therapist, or manual therapist? only count appointments outside of the hospital or rehabilitation center. add all appointments with these therapists together.  no appointments  ….. appointments question 17. how many appointments did you have with an occupational therapist during the past 6 months? only count appointments outside the hospital or rehabilitation center.  no appointments  ….. appointments question 18. how many appointments did you have with a psychologist, psychotherapist or psychiatrist during the past 6 months? only count appointments outside of the hospital or rehabilitation center. add all appointments with these professionals together  no appointments  ….. appointments question 19. how many appointments did you have with an occupational health physician during the past 6 months?  no appointments  ….. appointments question 20a. have you received home care during the past 6 months? this only refers to support or care received in connection with your prosthesis or amputation.  no  yes if you checked ‘’yes,’’ please answer question 20b through 20d. otherwise, continue with question 21. question 20b. what type of home care did you receive during the past 6 months?  household help e.g., vacuuming, making the bed, grocery shopping  personal care e.g., help with showering or dressing  nursing care e.g., applying bandages, administering medication, measuring blood pressure question 20c. how many weeks did you receive this home care? add up all weeks in the past 6 months. note: a 6-month period equals 26 weeks. household help: ….. weeks personal care: ….. weeks nursing care: ….. weeks https://doi.org/10.33137/cpoj.v8i2.45823 17 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 question 20d. how many hours of home care did you receive on average during these weeks? household help: average ….. hours per week personal care: average ….. hours per week nursing care: average ….. hours per week question 21a. have you received help from a family member or acquaintance during the past 6 months due to physical or psychological problems? this refers only to help received in connection with your prosthesis or amputation.  no  yes if you checked ‘’yes,’’ please answer question 21b through 21d. otherwise, continue with question 22. question 21b. what type of help did you receive from family members or acquaintances during the past 6 months? you may check more than one box  household help e.g., vacuuming, making the bed, grocery shopping, preparing food and drinks, caring for children  personal care e.g., help with showering or dressing, help with eating and drinking, administering medication  practical help e.g., support with walking, outings or visits to acquaintances, visits to the doctor or hospital, arranging help or financial matters question 21c. how many weeks did you receive this home care? add up all weeks in the past 6 months. note: a 6-month period equals 26 weeks. household help: ….. weeks personal care: ….. weeks practical help: ….. weeks question 21d. how many hours of home care did you receive on average during these weeks? household help: average ….. hours per week personal care: average ….. hours per week practical help: average ….. hours per week question 22. have you or your family members spent extra money in the past 6 months on any of the following items? these expenses are related to your prosthesis or amputation category no yes estimated amount (€) repairs of the prosthesis at own expense € home modifications at own expense € assistive devices at own expense € modifications to vehicles at own expense (car, bike, motorcycle) € equipment for hobbies/sports at own expense € other, namely …………………… € https://doi.org/10.33137/cpoj.v8i2.45823 18 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 question 23. what means of transportation did you use to travel from home to the hospital, rehabilitation center, or cpo/prosthetist?  not applicable  walking  bicycle  car  wheelchair or mobility scooter  public transport  taxi  other, namely ……………………………………………………………………… question 24. what is the one-way distance between your home and the hospital, rehabilitation center, and cpo/prosthetist? hospital: ….. kilometer rehabilitation center: ….. kilometer cpo/prosthetist: ….. kilometer do you have any questions or comments? if you have any questions or comments, please write them down below. ……………………………………………………………….………………………………… ……………………………………………………………….………………………………… ……………………………………………………………….………………………………… ……………………………………………………………….………………………………… ……………………………………………………………….………………………………… ……………………………………………………………….………………………………… explanation the following questions are about expenses incurred in connection with visits to the hospital, rehabilitation center and cpo/prosthetist. https://doi.org/10.33137/cpoj.v8i2.45823 19 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 appendix ii calculation of burden of disease the severity of an illness or condition can be expressed in a burden of disease score between 0 and 1. the different willingness-to-pay thresholds (wtp) are based on this score (table a1).24 table a1: willingness-to-pay thresholds in the netherlands. burden of disease reference threshold for maximum additional cost per qaly 0,1 – 0,4 up to €20,000 per qaly 0,41 – 0,7 up to €50,000 per qaly 0,71 – 1,0 up to €80,000 per qaly qaly: quality adjusted life year the burden of disease is calculated with the following equation: (𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝑄𝐴𝐿𝑌𝑠 𝑤𝑖𝑡ℎ𝑜𝑢𝑡 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛 − 𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝑄𝐴𝐿𝑌𝑠 𝑤𝑖𝑡ℎ 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛) 𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝑄𝐴𝐿𝑌𝑠 𝑤𝑖𝑡ℎ 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛 remaining qalys in a specific health state are calculated by multiplying the eq-5d-5l index score by the remaining number of years in that health state. to assess the burden of disease associated with lower limb amputation (lla), we compared the health-adjusted life expectancy between the general population in the netherlands and persons with peripheral vascular disease (pvd), the primary underlying condition in this study population.48 the average life expectancy of the general population is 85.5 years,49 while individuals with pvd have an estimated life expectancy of 81.5 years.50 the average eq-5d-5l index score for the general population of the netherlands was 0.86935 which is in line with the index scores of comparable countries that ranged from 0.82 to 0.90.51-54 for the lla population, eq-5d-5l index scores ranged from 0.462 to 0.531.37 the average age at amputation was estimated at 67 years, based on available cohort data. based on these parameters, we calculated the burden of disease across three scenarios, yielding a range of 0.48 to 0.60 (table a2). given that the range of burden of disease falls within the dutch wtp of €50,000 for a burden of disease between 0.41 and 0.70, this threshold is considered appropriate for evaluating interventions in the lla population. table a2: burden of disease scores. burden of disease score 1 smallest possible difference in eq-5d-5l index score 0,48 2 largest possible difference in eq-5d-5l index score 0,60 3 best fitting variables for lla population 0,50 https://doi.org/10.33137/cpoj.v8i2.45823 20 bosman c.e, van der sluis c.k, vrieling a.h, geertzen j.h.b, seves b.l, groen h. health economic evaluation of microprocessor and non-microprocessor controlled prosthetic knees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 3. https://doi.org/10.33137/cpoj.v8i2.45823 canadian prosthetics & orthotics journal issn: 2561-987x economic evaluation of microprocessor vs. non-microprocessor knees bosman et al., 2025 appendix iii table a3: detailed costs (in euros) and volumes by category and knee type. nmpk (n=44) mpk (n=58) outpatient visits cpo direct costs (€) 253.6 (n=29) 263.2 (n=45) travel costs (km) 93.2 (n=28) 51.7 (n=42) other hcp visits direct costs (€) general practitioner 74.4 (n=19) 36.2 (n=25) physiotherapist 99.8 (n=13) 293.0 (n=26) occupational therapist 2.76 (n=2) 2.52 (n=2) social worker 5.77 (n=1) 10.9 (n=1) psychologist/psychiatrist 2.50 (n=1) 20.8 (n=3) occupational health physician 22.7 (n=2) 3.44 (n=1) travel costs combined (€) 205.2 (n=22) 58.6 (n=37) other costs out of pocket costs (€) 1047 (n=17) 1407 (n=25) household care (h) household work 1434 (n=13) 461.5 (n=6) personal care 704 (n=4) n=0 nursing care n=0 n=0 informal care (h) 2357 (n=14) 3591 (n=16) productivity loss friction costs (€) 524.8 (n=1) 226.7 (n=3) presenteeism (€) 21.9 (n=4) 142.3 (n=3) nmpk: non-microprocessor controlled knee; mpk: microprocessor controlled knee; cpo: certified prosthetist/orthotist https://doi.org/10.33137/cpoj.v8i2.45823 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 1 2024 research article brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-anklefoot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i1.42799 1 brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 research article patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis brüggenjürgen b1*, eilers l1, seidinger s2, kannenberg a3, stukenborg-colsman c4 1 institute for health services research and technical orthopedics, orthopedic department medical school hannover (mhh) at diakovere annastift hospital, hannover, germany. 2 otto bock healthcare products gmbh, vienna, austria. 3 otto bock healthcare lp, austin, texas, usa. 4 foot department, orthopedic department medical school hannover (mhh) at diakovere annastift hospital, hannover, germany. open access abstract background: patients with neuromuscular knee instability who are fitted with orthotic devices experience issues such as pain, falls, mobility limitations, and restricted participation. objectives: to analyze the burden of disease in patients using a microprocessor-stance-and-swingcontrol orthosis (mp-ssco) and, if they had a previous orthosis, to compare their outcomes to those with previous use of a traditional knee-ankle-foot-orthosis (kafo) under real-world conditions. methodology: a structured cross-sectional survey was conducted in six orthotic and prosthetic clinics in germany. individuals who had been using an mp-ssco (c-brace) for at least six months, answered an internet-based survey to rate their current and recall previous device outcomes and experience. the questionnaire was self-developed based on established questionnaire design principles and pretested. patients' well-being dimensions were analyzed with likert scales. experiences with current and previous orthotic devices were compared. falls were analyzed both with and without outliers. findings: 21 individuals who had used a mp-ssco for an average duration of two years participated. fourteen patients had prior experience with a traditional kafo orthosis. among them, 78.6% recalled experiencing falls, with a combined annual frequency of 67.9 (sd=167.0, median=12.0) events. after excluding the two outliers (624 and 182 falls), a mean of 12.1 falls per patient per year was reported (range: 0 to 54, sd=15.9, median=8.5). with the mp-ssco, only 42.7% reported falls with an annual frequency of 5.3 (sd=17.0, median=0.0) falls (p<0.01). after excluding outliers for mp-ssco users, the average number of falls was 0.5 per year (range 0 to 3, sd=0.9, median=0.0). this value was significantly lower compared to the previous orthosis (p<0.01). with their previous kafo, 57.1% of the participants reported being able to walk downstairs, 14.3% to descend stairs with reciprocal gait, and 42.9% to vary their walking speeds. in contrast, 90.5% of mp-ssco users reported being capable of descending stairs, 81.0% reported to descend stairs with reciprocal gait (p<0.01), and 76.2% claimed they had the ability to walk with varying speeds (p=0.03). additionally, 71.4% of the respondents experienced an improvement in their engagement in activities with the mp-ssco. 50.0% reported pain with the previous orthosis, compared to 38.1% with the mp-ssco. pain intensity was higher for the previous orthosis use (3.8) compared to mp-ssco use (2.8) on a 1-5 scale (p=0.06). 93.3% of the participants regarded the mp-ssco as superior, noting an enhanced quality of life (qol) compared to the previous orthosis. conclusion: advanced orthotic technology may positively impact outcomes such as fall frequency, activities of daily living, fear of falling and pain. however, in this study, results from the previous orthosis use might have been influenced by recall bias. article info received: february 28, 2024 accepted: may 8, 2024 published: may 30, 2024 citation brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessorstance-and-swing-control kneeankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.4 2799 keywords knee-ankle-foot-orthosis, microprocessor-stance-and-swingcontrol orthosis, quality of life, activities of daily living, pain, falls, orthosis, disability, orthotic * corresponding author: prof. dr. med. bernd brüggenjürgen, mph head institute health services research and technical orthopedics, orthopedic department medical school hannover (mhh) at diakovere annastift hospital anna-von-borries-str. 1-7, 30625 hannover, germany tel.: +49 (511) 5354 821 e-mail: brueggenjuergen.bernd@mh-hannover.de; bernd.brueggenjuergen@diakovere.de orcid id: https://orcid.org/0000-0002-8866-0809 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 1, article no.1. 2024 https://doi.org/10.33137/cpoj.v7i1.42799 https://doi.org/10.33137/cpoj.v7i1.42799 https://doi.org/10.33137/cpoj.v7i1.42799 mailto:brueggenjuergen.bernd@mh-hannover.de https://jps.library.utoronto.ca/index.php/cpoj/index 2 brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor vs. traditional knee-ankle-foot orthoses: patient burden & outcomes brüggenjürgen et.al, 2024 introduction individuals affected by neuromuscular diseases or central nervous system disorders may experience joint instability which restricts their ability to participate in activities of daily living (adls). this limitation significantly impacts their engagement in social and professional aspects of life resulting in considerable patient burden. furthermore, neuromuscular knee instability caused by these conditions can lead to safety concerns for the patients. however, this increased fall risk, could potentially be mitigated by the provision of more advanced and effective orthotic devices.1,2 for these patients, orthotic devices designed to stabilize joints, such as ankle-foot orthoses (afos) or knee-anklefoot orthoses (kafos), can prove advantageous. afos may be sufficient if the knee instability is caused by paresis of the calf muscles. however, if the knee instability is caused by weakness of the quadriceps muscle, afos are no longer sufficient. in such cases, knee-ankle-foot orthoses (kafos) are frequently utilized to address knee instability associated with neuromuscular diseases and central nervous system disorders.3 kafos are equipped with knee joints that either lock for both stance and swing phase and are only released manually by the patient when sitting down (locked kafo) or lock for stance but are free for swing (free-swing kafos). locked kafos require substantial compensations to achieve sufficient toe clearance during the swing, such as circumduction, hip hiking, and vaulting.2,3 free-swing kafos are further distinguished in posterior-offset kafos and stance control orthoses (sco) that allow the patient to freely swing during the swing phase. these types of orthoses allow for a more natural movement pattern and enable to walk more smoothly on level ground while also providing the needed stability due to locking during the stance phase. nevertheless, ensuring safe control with these orthoses demands a certain level of remaining motor function in the affected limb. as a result, only a limited proportion of patients can be provided with these systems for reasons of safety.4 in the view of experts, the increased risk of falling with both locked and free-swing kafos and scos contributes to the diminished capacity to walk, which is further impaired by reduced coordination and balance resulting from physical deconditioning.5 in addition to the safety concerns associated with traditional orthoses, there are also mobility limitations and restrictions in adls as well as pain associated with orthosis use that need to be addressed.1,6 since 2012, a microprocessor stance and swing control orthosis (mp-ssco) has been available that controls the resistances against knee flexion and extension by hydraulic dampening during weight-bearing, thus enabling knee stance flexion and reciprocal slope and stair descent. it also provides stumble recovery and speed adaptation during the swing phase (ottobock, duderstadt, germany).7 compared to a locked kafo, an mp-ssco may facilitate the execution of numerous adls by making them easier, more natural, and safer than traditional leg orthosis technologies.6,8 mp-sscos may allow for walking with increased balance, speed, greater energy efficiency and increased safety.7 objective studies in clinical and lab-based biomechanical settings comparing mp-ssco to conventional kafos have already been performed. user reports emphasized that walking on uneven surfaces, stairs, and ramps was perceived as less challenging, resulting in increased walking autonomy. independence and mobility are important factors for the daily routine of individuals with lower limb motor impairments and have a decisive influence on their participation and quality of life (qol).9 the burden of disease among leg orthosis users has so far received little attention. very few studies have focused on demonstrating effectiveness in real-life settings.1 therefore, not only mobility and functionality but also safety and patient burden of disease may be helpful for capturing the indication-specific benefits of a therapy. according to interviewed experts, patients with muscular knee instability following neuromuscular or central nervous system injuries or conditions who use kafos or scos experience limited and restricted mobility, impaired gait patterns, and emotional strain.5 advanced orthotic technology, such as the mp-ssco, might contribute to better qol of patients, improved gait patterns with subsequent reduction of long-term consequences, and improved perceived dependability and stability of the orthosis while walking.5 nonetheless, there is currently only a limited amount of published data, particularly concerning patient-reported outcomes in an unsupervised home environment. by gathering insights in the patients' perspectives on the mp-ssco and previous orthoses used, it might be possible to identify unexpected or yet-unknown benefits of the mp-ssco. therefore, the aim of this study was to investigate whether the mp-ssco provides benefits recognized by patients in real life. a further rationale was to identify whether there were differences to the previous orthoses in patients' reported mobility and safety, satisfaction with the orthotic treatment, and pain. in addition to this assessment, the burden of disease was studied including social environment, aspects of participation in work and adls including health-promoting activities, and quality of life. methodology a structured cross-sectional survey was conducted in six orthotic and prosthetic clinics in germany. included in the https://doi.org/10.33137/cpoj.v7i1.42799 3 brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor vs. traditional knee-ankle-foot orthoses: patient burden & outcomes brüggenjürgen et.al, 2024 study were individuals who met the following criteria: they had been using a c-brace for more than six months and previously used a traditional locked or free-swing kafo or sco, or no orthosis prior to c-brace fitting. additionally, the participants had to be older than 18 years of age and provided informed consent. the survey was conducted in the period from december 2020 to november 2021 (seven months during covid-19 pandemic). the online tool lymesurvey was used to send out a link to the german-language questionnaire and collect the responses of participants. technical reliability was internally tested. pretest runs of the survey were carried out by different members of our departments. the survey comprised various topics, including demographics mobility/functionality, participation, safety, satisfaction, pain, and quality of life. questions and response categories were adapted, wherever possible, from existing pain, mobility, and falls questionnaires. the questionnaire employed different types of questions, primarily using likert scales with 1-5 point rating scales and one time a 1-10 scale for more detailed investigation of general safety perception. additionally, binary questions and open-response questions were used. the language of the questionnaire was german. all designers, testers, and participants were native german speakers. therefore, no translation of the questionnaire was necessary. the responses for the mp-ssco were concurrent, whereas the responses for the previous orthoses or the state before mp-ssco fitting had to be recalled from memory. patients provided informed consent and received a link via email, allowing them to answer the questions at their own pace in a predefined order from the comfort of their homes. the usability of the mp-ssco was assessed using a summary score that covered various categories and inquired about the patients’ satisfaction with the orthosis in different situations. the statistical analysis was conducted using ibm spss statistics version 29.0.0.0. the wilcoxon one-sided exact test was used for primary comparisons between traditional kafos/scos and mp-ssco. comparisons to traditional kafos were performed only in those mp-ssco users who had experience with such kafos (n=14). the mannwhitney test was used for sub-analyses. in the case of an extreme range of values, an outlier test was performed using a box plot. identified outliers were then checked for plausibility. in the case of legitimate outliers, two analyses were performed, one with and one without the outliers, to ensure maximum transparency. due to the exploratory nature of the study, no sample size calculation was performed. publication ethics the observatory investigation is conducted in accordance with the european medical device regulations (art. 82 mdr), the respective implementation the german medical device law (section 47 (paragraph 3) mpdg) and complies with all applicable data protection legislation.10 results out of 22 patients participating in the online survey, which took approximately 60 minutes to complete, 21 participants met the inclusion criteria and were included in the analysis. one participant was excluded due a protocol violation as his previous orthosis had been a first-generation mp-ssco rather than a traditional kafo. participants in the study had utilized the mp-ssco for a minimum of 11 months (mean 1.9, maximum 2.9 years). fourteen respondents had prior experience with another kafo, which they had used for an average of 12.5 years before transitioning to the mp-ssco. the respondents reported diverse underlying conditions, as indicated in table 1. among the 21 survey participants, 10 individuals had additional comorbidities. out of the 18 respondents aged below 65 years, 14 reported being employed. moreover, 13 participants were actively involved in more than six adls per week, such as shopping, cleaning, gardening, or exercising. additionally, out of the 13 patients who had to climb stairs to reach their homes, 10 did not have access to an elevator. most respondents had used their previous orthoses for more than eight hours per day. 57.1% of the respondents mentioned walking less than 1 km daily, 35.7% walked 1-3 km, and 7.1% reported walking 3-5 km a day with it. similarly, the mp-ssco was used for at least 8 hours per day on average. the daily walking distance with the mpssco was reported as less than 1 km by 38.1% of the respondents, 28.6% walked 1-3 km, and 33.3% covered a distance of 3-5 km. safety the general perception of safety of the prior kafo (n=14) scored 6.4 on a scale ranging from 1 (completely safe) to 10 (completely unsafe) (table 2). 21.4% of the respondents recalled feeling very safe while standing with the previous orthosis. however, when using the mp-ssco, the respondents' general perception of safety was rated with an average of 3.8, indicating an improved perception of safety compared to the previous orthosis (p=0.03). specifically, 76.2% of the respondents felt very safe while standing with the mp-ssco. with the previous orthosis, the average fear of falling, rated on a scale from 1 (very low) to 5 (very high), was 3.4. however, after switching to the mp-ssco, the average fear of falling significantly decreased to 1.5 (p<0.001). https://doi.org/10.33137/cpoj.v7i1.42799 4 brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor vs. traditional knee-ankle-foot orthoses: patient burden & outcomes brüggenjürgen et.al, 2024 table 1: participant characteristics. among the users of previous orthoses, nearly 78.6% recalled experiencing falls while using it. on average, these users recalled 67.9 falls per patient (range 0 to 624, median=12, sd=167.0) over the course of a year. after excluding the two outliers (624 and 182 falls), a mean of 12.1 falls per patient per year was reported (range: 0 to 54, median=8.5, sd=15.9). after being fitted with an mp-ssco, only 42.9% of the respondents stated that they had experienced falls in the last six months. the average number of falls with the mp-ssco was 5.3 per year (range 0 to 78, sd=17.0, median= 0.0), which was significantly lower compared to the previous orthosis (p<0.001). in patients currently employing mp-ssco, three outliers of 78 and two occurrences of 12 falls per year were identified. of note, one user reported experiencing such outliers both with the preceding orthosis and the current mp-ssco. after excluding outliers for current mp-ssco users, the average number of falls was 0.5 per year (range 0 to 3, sd=0.9, median=0.0). this value was significantly lower compared to the previous orthosis (p<0.01). 76.2% of all participants named safety the most critical aspect when assessing the orthosis. mobility & functionality among the respondents who had used traditional kafos before, 85.7% mentioned that they had also used additional assistive devices alongside their previous orthoses (table 2). the majority of participants relied on walking sticks or forearm crutches, while 35.7% had used wheelchairs (manual or electric) or scooters, and these devices had been used more than 5 times a week by most. out of the mp-ssco users, only 42.9% required other aids such as walking sticks and forearm supports. furthermore, 35.0% of the respondents had a wheelchair that the majority of them used 5 to 10 times a week. the individuals were asked about their ability to perform various adls in their lives including walking at different speeds. in three of the four situations described, there was a significant improvement, while the improvement in one situation just failed to attain significance since using the mpssco (figure 1). the most significant improvement was observed in reciprocal stair descent, with the percentage of participants able to descend a stair with reciprocal gait increasing from 14.3% with the previous orthosis to 81.0% with the mp-ssco (p<0.01). regarding their gait pattern, 92.9% of the participants recalled poor or very poor symmetry with the previous kafo. however, when using the mp-ssco, this percentage significantly reduced to only 9.5% (p<0.001). asked about how they assessed their ability to descend stairs, 75.0% of the patients rated it as bad or very bad with their previous orthosis. however, with the mp-ssco, 94.7% reported being able to descend stairs well or very well (p=0.01). the average usability rating for the previous orthosis was 3.9 (sd=0.6), which indicates poor usability on a scale ranging from 1 (very good) to 5 (very poor). in contrast, the average usability rating for the mp-ssco was 2.1 (sd=0.7), indicating good usability (p<0.001). participants being able to pursue physically demanding activities are presented in figure 2. n % age (years) all, mean (sd)=48.1 (14.0); min=27; max=71 male, mean (sd)= 53.6 (12.0) female, mean (sd)= 42.1 (14.0) gender female 10 47.6 male 11 52.4 bmi all, mean (sd)=25.4 (4.0); min=19.0; max=33.6 normal weight (bmi 18.5 – 24.9) 11 52.4 overweight (25.0 – 29.9) 7 33.3 obese (≥ 30) 3 14.3 underlying condition poliomyelitis 8 38.1 incomplete paraplegia 4 19.1 neuromuscular diseases 2 9.5 traumatic brain injury (tbi) 1 4.8 other 6 28.6 comorbidities (multiple responses possible, percentages for those reporting comorbidities) none 11 52.4 diabetes 1 10.0 impaired vision 1 10.0 neuropathy 1 10.0 total hip replacement 1 10.0 hypertension 4 40.0 coronary heart disease 1 10.0 other 7 70.0 affected leg right 6 28.6 left 14 66.7 both 1 4.8 previous orthosis before mp-ssco free swing knee-ankle-footorthosis (kafo/sco) 10 47.6 locked knee-ankle-foot-orthosis (kafo) 4 19.0 no previous orthosis 7 33.3 living alone yes 8 38.1 no 13 61.9 independent household management yes 9 42.9 no 1 4.8 partial 11 52.4 residential environment flat 10 47.6 hilly 8 38.1 mountainous 3 14.3 residential floor 0 – ground level 8 38.1 1st 7 33.3 2nd 2 9.5 3rd 1 4.8 missing for non-ground level 3 14.3 orthosis since (years) all, mean (sd)=12.5 (15.7); min=1.7; max=54.5 https://doi.org/10.33137/cpoj.v7i1.42799 5 brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor vs. traditional knee-ankle-foot orthoses: patient burden & outcomes brüggenjürgen et.al, 2024 pain out of all prior kafo respondents, 50.0% had experienced discomfort or pain with their previous orthosis, primarily in the form of low-back pain (table 2). on an overall average pain intensity scale from 1 to 5, with 1 representing very mild pain and 5 indicating very severe pain, the average pain intensity was 3.8. table 2: comparison of previous orthosis and c-brace regarding safety, functionality, and pain. mean previous kafo (n=14) mean – c-brace in previous kafo users (n=14) p-value mean – c-brace in previous kafo and non-user (n=21) safety general perception of safety1 6.4 3.8 0.03 4.1 safety while standing2 2.8 1.6 0.20 1.4 fear of falling3 3.4 1.5 <0.001 1.8 falls occurred? 4 0.8 0.4 0.35 0.4 number of falls per year 67.9 1.1 <0.001 5.3 number of falls per year, outliers excluded 12.1 (n=12) 0.3 (n=13) <0.01 0.5 (n=18) mobility & functionality assistive devices used4 0.9 0.6 0.15 0.4 usability5 3.9 2.0 <0.001 2.1 symmetry of gait5 4.5 2.1 <0.001 2.2 ability to descend stairs5 4.0 1. 7 0.01 1.7 ability to descend stairs4 0.6 0.9 0.06 0.9 reciprocal stair descend4 0.1 0.8 <0.01 0.8 ability to walk an incline4 0.5 1.0 0.01 0.9 walking at varying walking speeds4 0.4 0.8 0.03 0.8 pain pain4 0.5 0.3 0.08 0.4 pain intensity6 3.8 2.1 0.06 2.8 pain influence7 3.7 1.3 0.02 1. 7 1scale ranging from 1 (completely safe) to 10 (completely unsafe) 2scale ranging from 1 (very safe) to 5 (not safe) 3scale ranging from 1 (very low) to 5 (very high) 4 no=0 / yes=1 5 scale ranging from 1 (very good) to 5 (very poor) 6scale ranging from 1 (very mild pain) to 5 (very severe pain 7scale ranging from 1 (no impact) to 5 (severe impact) figure 1: usability of previous kafo vs. mp-ssco separately reported for those with previous experience and all (percentage of participants indicating their capability to perform (yes=1, no=0)) 76% 95% 81% 91% 79% 100% 79% 86% 43% 50% 14% 57% 0% 20% 40% 60% 80% 100% walking at various speeds (p=0.03) ability to walk on an incline (p<0.01) reciprocal stair descent (p<0.01) ability to descend stairs (p=0.06) usability of previous kafo vs. mp-ssco previous kafo (n=14) mp-ssco (previous kafo, n=14) mp-ssco (all, n=21) https://doi.org/10.33137/cpoj.v7i1.42799 6 brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor vs. traditional knee-ankle-foot orthoses: patient burden & outcomes brüggenjürgen et.al, 2024 with use and after getting accustomed to the new mpssco, 38.1% of the participants reported pain (p=0.06). the overall average pain intensity for this group was 2.8. the impact of pain on the respondents' daily lives was evaluated using a likert scale with 1 indicating no impact and 5 indicating severe impact. the average impact of the previous orthosis was 3.7 (quite severe) while that of the mp-ssco was 1.7 (p=0.02). those participants engaging in sports reported experiencing significantly more pain (p=0.03). satisfaction with the mp-ssco & quality of life 80.0% of the respondents reported that the c-brace treatment was considerably superior to their previous orthosis. the satisfaction levels were high, with 71.4% stating they were very satisfied, and an additional 23.8% expressed to be satisfied with the c-brace. only 4.7% were not satisfied. as shown in figure 3, 15 out of 16 participants who responded on quality of life (qol) believed that using the cbrace positively impacted their quality of life. some patients mentioned specific improvements, such as one individual being able to go skiing and another to start dance lessons. additionally, many patients appreciated the ability to interact with others at an eye-to-eye level, which had a significant impact on their emotional well-being. when ranking the benefits, the respondents considered safety, effectiveness, and weight as the most crucial factors in their evaluation. figure 3: individuals reporting improvements in quality of life since using the mp-ssco (n=16). discussion individuals who had been using an mp-ssco (c-brace) for a minimum of six months were invited to participate in an online survey. twenty-one individuals were included in the analysis. the aim was to gain insights into the real-world impact of conventional locked and free-swing kafos or scos from the patients' perspective and to understand the differences experienced after using the mp-ssco. the survey covered various aspects related to safety, mobility, functionality, participation, and pain. the age of the participants varied from 27 to 71 years, and females 73% 20% 0% 7% 0% 0% 10% 20% 30% 40% 50% 60% 70% 80% significantly better better the same worse significantly worse improvement of quality of life since using the c-brace figure 2: comparison of physically demanding activities regularly undertaken of participants to the general population: shopping11; cleaning12; gardening13; childcare14 caring15; sport16; leisure16; walk17. 76% 86% 48% 48% 14% 57% 57% 95% 26% 88% 45% 58% 20% 13% 71% 89% 0% 20% 40% 60% 80% 100% taking a walk excursions and leisure activities sport caring for those in need of care childcare gardening cleaning shopping participants reporting regularly undertaken activities general population mp-ssco (n=21) https://doi.org/10.33137/cpoj.v7i1.42799 7 brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor vs. traditional knee-ankle-foot orthoses: patient burden & outcomes brüggenjürgen et.al, 2024 accounted for 47.6% of the sample, representing relevant user groups for the mp-ssco in terms of both age and gender. a major factor that restricts people’s mobility is the inability to negotiate stairs with reciprocal gait. there are still many places that are not accessible to persons with mobility limitations and/or restrictions, and the ability to negotiate stairs is essential for participation.18 when rating the ability to descend stairs, 12.5% of the patients using kafos recalled it to be good. with the mp-ssco, 94.7% said they could descend stairs well or very well improving their activities of daily living. furthermore, more than one third of mp-ssco users achieved walking distances of the general population a healthy person in germany walks approximately 4 km a day.19 55% of people with disabilities never engage in sports, while only 33% of people without disabilities do not.16 users of the mp-ssco demonstrated increased levels of sports activities, with 48% of individuals reporting regular participation in sports. additionally, when it comes to shopping, excursions, and leisure activities,11 the mpssco users achieved levels similar as those of the general population as shown in figure 2. however, our study sample may not accurately reflect the broader population, and there is a lack of published activity data with sufficient detail to enable a more precise comparison within the studied populations. consequently, our evaluation sought to determine if individuals equipped with the mp-ssco experienced significant limitations in their daily activities. given the considerable personal commitment and potential financial investment required for orthotic provision, it is presumed that the subset of individuals using the mp-ssco represents an active and potentially affluent subgroup seeking to maximize their newfound opportunities. consequently, the notably higher prevalence of gardening and walking activities could be attributed to two factors. firstly, a higher proportion of mp-ssco users may have access to private yards or gardens. secondly, walking may be perceived as a privilege or preferred form of exercise compared to other physical activities such as jogging. the use of mp-sscos resulted in a reduction in the number of individuals who recalled pain, a decrease in average pain intensity, and a significant reduction in limitations in their adls. it is important to consider that the increased activity levels of patients since using the mp-ssco may have influenced the observed differences. interestingly, when comparing mp-ssco users who exercise with those who do not, the ones who exercise tended to report more pain on average. despite the presence of some pain while using the mp-ssco, it is perceived as significantly reduced in intensity and less restrictive in adls. the majority of patients expressed satisfaction with the c-brace, which was evident in its significantly improved usability score compared to the previous orthosis. the conditions leading to the use of an mp-ssco in this patient survey were comparable to those mentioned in interviews with experts.5 according to the experts interviewed, the primary patient burdens leading to the use of a mp-ssco were "limited mobility," followed by "emotional stress" and "altered gait pattern." the most significant factors affecting patients were identified as the dependability and stability while walking, restoring a natural gait, and the ability to perform adls.5 our patient survey revealed that safety and effectiveness were considered as the leading relevant aspects, and that aligns with the views expressed by the experts. however, the weight of the orthosis emerged as the third-most relevant aspect, which was not explicitly highlighted by the experts. a health-technology assessment (hta) and systematic patient survey identified the reduction of pain, falls, and the improved ability to perform adls as the outcomes primarily desired by patients, while the most valued orthosis features were reported to be effectiveness, reliability, comfort, and durability, as presented in table 3. however, the existing evidence on the effectiveness of orthoses is limited, especially when focusing on the most important outcomes from the perspective of the users.1 among the individuals in our patient survey, 76.2% regarded safety as the most critical aspect when assessing the orthosis. in contrast, the experts prioritized dependability and stability, and they did not consider safety to be as significant a factor when evaluating an orthosis.5 with the mp-ssco compared to traditional kafos, the average number of falls per year was reduced significantly by 92.2%. it is noteworthy that the presence of extreme outliers in the survey may have influenced these averages. as per the expert interviews, falls occurred in 71.5% of patients using kafos or scos with a combined annual frequency of 7.0 fall events. in contrast, the experts had observed falls in only 7.2% of mp-ssco users and an annual frequency of 2.2 fall events per year. this suggests that the use of mp-ssco resulted in a considerable reduction in fall incidents compared to traditional types of orthoses.5 however, the numbers also suggest that patient may not report all falls to their treating physicians. according to the experts, advanced orthotic devices may enhance physical and psychological health and well-being by enabling patients to pursue their daily routines.5 this was directly confirmed by patients’ results in our study regarding usability and improved quality of life. improved gait patterns https://doi.org/10.33137/cpoj.v7i1.42799 8 brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor vs. traditional knee-ankle-foot orthoses: patient burden & outcomes brüggenjürgen et.al, 2024 were not explicitly mentioned by patients but might result in subsequent reduction of long-term consequences, according to experts.5 experts’ and patients’ perspectives might differ. horenkamp et al.20 investigated the impact of obtaining results from different perspectives. experts’ estimate on resource use or patients’ burden was principally lower when compared to patients’ own reported outcomes. hence, this is in line with the comparative results reported in our analysis.20 our results confirm the need for incorporating outcomes that are relevant to the patients into research of orthotic devices for knee instability related to neuromuscular and central nervous system conditions. study limitations the retrospective nature of this study results in a possible recall bias. recall bias refers to different results in interviews or self-reports of previous exposures or events. it is therefore primarily a problem in retrospective studies. this collection of past information, especially on the situation before the current mp-ssco and when actively using it, carries the risk of recall bias as a form of information bias when collecting retrospective data. in general, patients tend to overestimate pain and underestimate mobility in the past.21 additionally, there could be a technology bias since all patients were already using the mp-ssco at the time of the survey, especially affecting previous kafo results. this refers to preconceived positive notions of the used technology and hence biased opinions in favor of adopting the technology.22 another consequence arises from the number of individuals who participated in this study, potentially leading to a bias due to a greater influence of extreme values. finally, though outcome measures in this exploratory study were developed according to sound empirical practices and applied standard response items such as likert-scales, a prior validation had not been conducted. conclusion individuals with knee instability caused by neuromuscular diseases or central nervous system disorders face limitations and restrictions in mobility, impaired gait patterns, and experience emotional strain when using conventional locked and free-swing kafos. the implementation of advanced orthotic technology has the potential to positively impact patient-specific parameters such as fall frequency, fear of falling, pain, activities of daily living, and reliance on other assistive devices. notably, the use of mp-ssco resulted in a significant reduction in the frequency of falls compared to conventional kafos. when assessing their orthoses, individuals emphasized safety, effectiveness, and weight as the most relevant attributes. in contrast, experts considered dependability and stability as the most crucial aspects. this highlights the importance of involving patients in the orthosis selection process and taking into account the aspects that users rate as most significant. furthermore, individuals' quality of life was identified as a relevant dimension and an area that could see substantial improvements for kafos/scos users. table 3: comparison of leading aspects from different survey sources. patient survey expert survey5 o´connor analysis1 important aspects • perception of safety and high stability while walking • physiologic gait • participation in daily life • engagement in daily activity patients desired outcomes • safety • independence • quality of life • meeting fellow people on eye level • improved gait • reliability • stability while walking • physiologic gait • ability to perform daily routine (data on file) • reduction in pain, falls or trips. • improved balance and stability most valued features • effectiveness • safety • weight • improved quality of life • improved gait patterns • high dependability of the orthosis • effectiveness • reliability • comfort and durability frustration uncomfortable (n=1) and not water proof (n=1) • setting correct indication • intensive service support • access to reimbursement decision maker perceived deficiencies in service provision related to: • appointment • administrative systems and • referral pathways lead patient burden • restriction of mobility, emotional strain, impaired gait pattern other burden • appearance and good look • cosmetic issues • appearance want to look as normal as possible. • women are especially affected in dressing https://doi.org/10.33137/cpoj.v7i1.42799 9 brüggenjürgen b, eilers l, seidinger s, kannenberg a, stukenborg-colsman c. patients’ burden using microprocessor-stance-and-swing-control knee-ankle-foot orthoses and outcomes compared to those with prior traditional knee-ankle-foot-orthosis. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.1. https://doi.org/10.33137/cpoj.v7i1.42799 canadian prosthetics & orthotics journal issn: 2561-987x microprocessor vs. traditional knee-ankle-foot orthoses: patient burden & outcomes brüggenjürgen et.al, 2024 acknowledgements we wish to thank all patients that participated in the study. declaration of conflicting interests bernd brüggenjürgen: received lecture fees. lena eilers: nothing to be declared. susanne seidinger: full-time employee of ottobock. andreas kannenberg: full-time employee of ottobock. christina stukenborg-colsman: nothing to be declared. authors contribution bernd brüggenjürgen: conception and design, analysis and drafting of the paper, interpretation of the data; revising it critically for intellectual content and final approval of the version to be published. lena eilers: analysis and drafting of the paper, interpretation of the data; revising it critically for intellectual content. susanne seidinger: conception and design, interpretation of the data; revising it critically for intellectual content and final approval of the version to be published. andreas kannenberg: interpretation of the data; revising it critically for intellectual content and final approval of the version to be published. christina stukenborg-colsman: interpretation of the data; revising the manuscript critically for intellectual content and final approval of the version to be published. sources of support this work was supported by an unrestricted grant of ottobock healthcare products gmbh, wien. references 1.o'connor j, mccaughan d, mcdaid c, booth a, fayter d, rodriguez-lopez r, et al. orthotic management of instability of the knee related to neuromuscular and central nervous system disorders: systematic review, qualitative study, survey and costing analysis. health technol assess. 2016;20(55):1-262. doi: 10.3310/hta20550 2.fox jr, lovegreen w. 22 lower limb orthoses. in: webster jb, murphy dp, editors. atlas of orthoses and assistive devices (fifth edition). philadelphia: elsevier; 2019. p. 239-46.e1 3.mcdaid c, fayter d, booth a, o'connor j, rodriguez-lopez r, mccaughan d, et al. systematic review of the evidence on orthotic devices for the management of knee instability related to neuromuscular and central nervous system disorders. bmj open. 2017;7(9):e015927. doi: 10.1136/bmjopen-2017-015927 4.schmalz t, pröbsting e, auberger r, siewert g. a functional comparison of conventional knee–ankle–foot orthoses and a microprocessor-controlled leg orthosis system based on biomechanical parameters. prosthet orthot int. 2016;40(2):277-86. doi: 10.1177/0309364614546524 5.brüggenjürgen b, braatz f, greitemann b, drewitz h, ruetz a, schäfer m, et al. experts’ perceived patient burden and outcomes of knee-ankle-foot-orthoses (kafos) vs. microprocessor-stanceand-swing-phase-controlled-knee-ankle-foot orthoses (mpsscos). can prosthet orthot j. 2022;5(1). doi: 10.33137/cpoj. v5i1.37795 6.pröbsting e, kannenberg a, zacharias b. safety and walking ability of kafo users with the c-brace((r)) orthotronic mobility system, a new microprocessor stance and swing control orthosis. prosthet orthot int. 2017;41(1):65-77. doi: 10.1177/ 0309364616637954 7.deems-dluhy s, hoppe-ludwig s, mummidisetty ck, semik p, heinemann aw, jayaraman a. microprocessor controlled knee ankle foot orthosis (kafo) vs stance control vs locked kafo: a randomized controlled trial. arch phys med rehabil. 2021;102(2):233-44. doi:10.1016/j.apmr.2020.08.013 8.ruetz a, dibello t, toelle c, hemmen b, wening j, weber e, et al. a microprocessor stance and swing control orthosis improves balance, risk of falling, mobility, function, and quality of life of individuals dependent on a knee-ankle-foot orthosis for ambulation. disabil rehabil. 2023:1-14. doi: 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[cited 2024 february 28]. available from: https://de.statista.com/statistik/daten/studie/171913/umfrage/haeu figkeit-spazieren-gehen-in-der-freizeit/# 18.kühnis j, wüst n. erleben von barrieren im öffentlichen raum für personen im rollstuhl und die auswirkungen auf die gesellschaftliche partizipation [experiencing barriers in public spaces for people in wheelchairs and the effects on social participation in society]. 2022. bachlor thesis, doi:10.21256/zhaw-26080 19.althoff t, sosic r, hicks jl, king ac, delp sl, leskovec j. large-scale physical activity data reveal worldwide activity inequality. nature. 2017;547(7663):336-9. doi: 10.1038/ nature23018 20.horenkamp-sonntag, d. (2016). externe validität von gkvroutinedaten [external validity of gkv routine data]. doctoral dissertation. doi:10.17169/refubium-12119 21.lingard ea, wright ea, sledge cb, kinemax outcomes g. pitfalls of using patient recall to derive preoperative status in outcome studies of total knee arthroplasty. j bone joint surg am. 2001;83(8):1149-56. doi: 10.2106/00004623-200108000-00003 22.timbie jw, fox ds, van busum k, schneider ec. five reasons that many comparative effectiveness studies fail to change patient care and clinical practice. health aff (millwood). 2012;31(10):216875. doi: 10.1377/hlthaff.2012.0150 https://doi.org/10.33137/cpoj.v7i1.42799 https://www.prognos.com/de/projekt/teilhabebericht-ueber-die-lebenslagen-von-menschen-mit-beeintraechtigungen https://www.prognos.com/de/projekt/teilhabebericht-ueber-die-lebenslagen-von-menschen-mit-beeintraechtigungen https://de.statista.com/statistik/daten/studie/171913/umfrage/haeufigkeit-spazieren-gehen-in-der-freizeit/#:~:text=umfrage%20in%20deutschland%20zur%20h%c3%a4ufigkeit%20des%20spazierengehens%20in%20der%20freizeit%20bis%202021&text=im%20jahr%202021%20gab%20es,die%20mehrmals%20w%c3%b6chentlich%20spazieren%20gingen https://de.statista.com/statistik/daten/studie/171913/umfrage/haeufigkeit-spazieren-gehen-in-der-freizeit/#:~:text=umfrage%20in%20deutschland%20zur%20h%c3%a4ufigkeit%20des%20spazierengehens%20in%20der%20freizeit%20bis%202021&text=im%20jahr%202021%20gab%20es,die%20mehrmals%20w%c3%b6chentlich%20spazieren%20gingen https://doi.org/10.21256/zhaw-26080 http://dx.doi.org/10.17169/refubium-12119 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 1 2025 review article edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i1.43073 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 review article the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review edwards r*, murray l, buis a department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. introduction acquired amputation can result from a number of pathologies such as diabetes, vascular disease, cancer and trauma. globally, in 2017, 58 million people were living with an amputation due to traumatic causes.1 at a regional level, between 1990 and 2019, south asia saw the highest prevalence during this period with 100 million traumatic amputations. traumatic amputation accounts for 45% of all amputations. individuals in this group typically have no additional comorbidities or pathologies and are likely to return to a level of activity similar to their pre-amputation status.2 however, these prosthetic users who are wearing the prosthesis for longer periods, and actively engaged in employment and hobbies, often report complications related to thermal discomfort, regardless of geographical location.3 the scientific literature regarding thermal discomfort and perspiration has been documented by multiple authors. it is for instance reported, that persons who wear a prosthesis are more susceptible to increased heat and perspiration, open access abstract background: thermal discomfort is one of the most prevalent issues experienced by lower-limb prosthetic users where, on average, 54% of users report thermal-related issues. this arises from wearing a prosthetic socket, which may disrupt the thermoregulatory system due to the low thermal conductivity of materials used in prosthetic sockets and liners. despite the reported prevalence, there is little understanding of the impact of wearing a prosthesis on the body’s thermoregulatory system and how users perceive thermal discomfort. objective(s): this review aimed to evaluate the current understanding of how human thermoregulation correlates with subjective measures of thermal discomfort among lower-limb prosthetic users. it sought to gain a deeper understanding of how thermoregulatory parameters compare and relate to the subjective experience of thermal discomfort in this population. methodology: the study design followed a scoping review structure to identify gaps in knowledge on the topic. a literature search was conducted across five online databases: medline (proquest), embase, cochrane, cinahl and psycinfo. the searches covered literature from the earliest available date in each database up until february 2024. a search strategy was created to identify the relevant literature. an inclusion/exclusion criterion was then applied to identify studies that only measured either physiological or psychological aspects of thermoregulation and compared these aspects to thermal discomfort/comfort feedback. the qualsyst critical appraisal tool was used to gain quality score for each included article. findings: 8 articles were identified for inclusion in this review, confirming a dearth in research into how wearing a prosthesis affects thermoregulation at the body/device interface (bdi) and the perception of thermal discomfort. furthermore, it raised question to the relevance of using residual limb skin temperature measurements to assess thermal discomfort in lower-limb prosthetics. perspiration at the bdi emerged as a potentially significant contributor to thermal discomfort, a consensus reflected in the literature. conclusion: despite significant technological advancements, thermal discomfort remains a persistent issue. therefore, further research is warranted to further understand how wearing a prosthesis affects the thermoregulatory system, enabling the development of innovative components which can mitigate thermal discomfort and in turn improve the quality of life of lower-limb prosthetic users. article info received: april 12, 2024 accepted: march 17, 2025 published: march 28, 2025 citation edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj. v8i1.43073 keywords literature review; scoping review; thermal discomfort; lower limb amputation; prosthesis; skin; prosthetic; amputation; body/device interface; thermoregulation; temperature; perspiration. * corresponding author: professor arjan buis, phd department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. e-mail: arjan.buis@strath.ac.uk orcid id: https://orcid.org/0000-0003-3947-293x journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 1, article no.3. 2025 https://doi.org/10.33137/cpoj.v8i1.43073 https://doi.org/10.33137/cpoj.v8i1.43073 https://doi.org/10.33137/cpoj.v8i1.43073 mailto:arjan.buis@strath.ac.uk https://orcid.org/0000-0003-3947-293x https://jps.library.utoronto.ca/index.php/cpoj/index 2 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 evident in the fact that, on average, 54% of prosthetic users report thermal-related issues.3 klute et al. described that susceptibility arises from wearing a prosthetic socket, which may disrupt the thermoregulatory system due to the low thermal conductivity of the materials used in manufacturing prosthetic sockets and liners.4 despite the reported prevalence of the issue, there is little understanding of the impact of wearing a prosthesis on the body's thermoregulatory system and how users perceive thermal discomfort. current research into thermal discomfort has been focused more on lower-limb prosthetics with one study reporting that people with a transfemoral amputation rated thermal discomfort to be higher compared to people with a transtibial amputation.5 overall prosthetic socket comfort is essential for prosthetic use and, clinicians and prosthetic companies strive to deliver the best fitting and most comfortable sockets possible. this is to ensure user satisfaction, a reduction in prosthetic abandonment and increasing quality of life.6 ensuring a good socket fit requires appropriate force transmission coupled with a reliable suspension method provided by a bespoke, socket. this, however, encloses the residuum which can hinder heat exchange, leading to elevated skin temperature and perspiration at the body/device interface (bdi). in addition, patella tendonbearing sockets are frequently being replaced by total surface-bearing sockets, which often require an elastomeric liner which, although functionally advantageous, could increase the incidence of prosthetic-related thermal stress.7 the skin is vital for thermoregulation, enabling heat exchange between the body and the external environment, known as sensible heat transfer. this process involves heat loss through subcutaneous blood vessels via vasodilation, evaporative heat loss via sweating and the flattening of hairs to remove the insulating layer of air over the skin.8 donning a prosthesis impairs heat transfer between the residual limb and the environment for all three of these mechanisms by creating an impermeable barrier at the bdi. this creates the potential for an unnaturally warm and moist environment, leading to skin pathologies and functional issues with the prosthesis. users may experience skin irritation or blistering which combined with the unfavorable environment can lead to infections.9 pistoning, known as relative motion between the residual limb and the socket, can also occur due to micro-film lubrication as a result of sweat build-up, affecting socket suspension. henao et al. discovered an increase in the coefficient of friction at the bdi in the presence of sweat which, when coupled with pistoning, could rapidly increase the onset of blistering.10 the human thermoregulatory process tightly regulates body core temperature around 37°c against thermal disturbances to maintain homeostasis and can be divided into two categories: autonomic and behavioral. the autonomic thermoregulatory process is involuntary and can alter heat production and dissipation through shivering or non-shivering thermogenesis, or as aforementioned, through vasodilation of subcutaneous blood vessels and evaporative heat loss.11 behavioral thermoregulation is a voluntary process whereby a conscious decision is made to adapt to a change in the thermal environment. for example, seeking shade in a hot climate or adding clothing when too cold.12 human perception of thermal discomfort may play an important role in activating behavioral thermoregulation. discomfort arises when thermal stimuli result in a deviation of core temperature from the norm.13 hensen et al. has defined thermal comfort as “that condition of mind which expresses satisfaction with the thermal environment”.14 it was also defined by the american society of heating, refrigerating and air-conditioning engineers (ahsrea) as “the condition of mind in which satisfaction is expressed with the thermal environment”.15 these definitions allude to the fact that thermal comfort is a state of mind, rather than a state condition, indicating its subjectivity with it being influenced by personal differences in mood, culture and other individual, organizational and social factors.16 while thermal discomfort plays a role in autonomic thermoregulation, it primarily drives behavioral thermoregulation due to its significant influence on skin temperature. skin surface temperature has a relatively greater contribution to subjective thermal discomfort than the autonomic response. due to this, thermal comfort initiates behavioral thermoregulation before autonomic thermoregulation. this is due to autonomic thermoregulation being a more metabolically demanding response that maintains body temperature.17 when wearing a prosthesis, the heat exchange processes through autonomic thermoregulation could be compromised. in addition, the behavioral thermoregulatory act is for the user to remove their prosthesis. this should not have to occur, but if necessary, this may not always be possible during day-to-day activities, compromising this thermoregulatory process. with the knowledge that thermal discomfort may play a key role in both autonomic and behavioral thermoregulation, and that numerous prosthetics users report thermal discomfort, this scoping review has studied the available literature that compares thermoregulation to thermal discomfort in lower-limb prosthetics. it also assessed the breadth and depth of understanding of the impact that wearing a prosthesis has on the fundamental physiological processes involved in thermoregulation at the bdi. methodology search strategy a scoping review was undertaken to assess the current knowledge relating to the involvement of human thermoregulation in thermal discomfort for lower-limb prosthetic users. this review aimed to assess the different https://doi.org/10.33137/cpoj.v8i1.43073 3 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 thermoregulatory factors, either physiological or psychological, to gain a deeper understanding of how human temperature regulation may be influencing thermal discomfort or vice versa. the methodology for this literature review was chosen to identify research gaps to guide future experimental research into the perception of thermal discomfort in lower-limb prosthetics. a literature search was conducted between 15/01/24 and 02/02/24. the search was completed across 5 online databases; medline (proquest), embase, cochrane, cinahl and psycinfo and the results were transferred to endnote. keywords were combined with boolean operators to create a search strategy. the strategy utilized is highlighted in table 1. table 1: search strategy used across all five databases. search selection the searches spanned the period from the earliest date of each database until february 2024. all chosen articles from each database were then transferred into the endnote (version 20.3.0.17787) reference management software, and all duplicates were removed. search results from each database were screened by title and abstract. the relevant articles which matched the inclusion and exclusion criteria, as presented in table 2, were then chosen. articles were included if the abstracts discussed or measured thermoregulation and/or thermoregulatory processes in either physiological or psychological terms and made a comparison to thermal discomfort in lower-limb prosthetics. articles inclusion was assessed by two researchers. four articles were identified by one reviewer and not the other and were discussed as a group.18-21 upon discussion, these articles were not included in the review. although they measured thermoregulatory parameters and addressed thermal discomfort as an issue, they did not discuss or record subjective measurements for comparison with the thermoregulatory parameters. data extraction data from the remaining articles were extracted and documented in a data extraction table (table 3), providing an overview of the current literature and highlighting emerging themes. the information gathered was as follows: author, year of publication, location of the study, sample size, study design, participant demographic, testing interventions temperature/perspiration outcomes and the qualsyst quality threshold score.22 the findings are summarized in the attached data extraction table. table 2: inclusion and exclusion criteria. inclusion criteria exclusion criteria • studies published in english. • only peer-reviewed. • studies that measured thermoregulation and/or thermoregulatory processes and made a comparison to thermal discomfort feedback. • studies that included lower-limb prosthetics users. • literature review studies. • studies that did not measure physiological or psychological aspects of thermoregulation and make a comparison to thermal dis/comfort feedback. • studies conducted on animals or prototypes. quality assessment following the application of the inclusion and exclusion criteria to the titles and abstracts, all chosen full-text articles were critically appraised using the qualsyst tool. proposed by the alberta heritage foundation, this tool allows for a quantitative and reproducible method of identifying literature quality by providing an output number.22 the assessment of quantitative studies consists of 14 questions. a score of 0 to 2 can be awarded for each question. a summary score is calculated for each paper indicating its quality. the qualsyst tool suggests a cut-off score of 0.75 for a paper to be included in a review article. the summary score calculation process can be seen in appendix. the quality of the paper is then further defined in a literature review with a scoring system defined by lee et al. as; strong (summary score of >0.80), good (summary score of 0.710.79), adequate (summary score of 0.5-0.7) and limited (summary score of <0.5).23 the qualsyst score for each study can be seen in the data extraction table (table 3). due to the low number of included articles, the exclusion of papers lower than the cut-off score was not appropriate, therefore, quality assessment was conducted as an outcome measure to promote discussion, rather than an exclusion criterion. results the search yielded 2612 articles after the removal of duplications. after the inclusion and exclusion criteria were applied to the title and abstract of the remaining articles, 8 were taken forward for quality assessment and review. this selection process can be seen in the prisma flow chart shown in figure 1. four studies achieved an adequate score, two achieved a good score and two achieved a strong score. the results discussed in the section are presented in more detail in table 3. search terms 1 thermoregulation or “thermal response” or temperature 2 prosthe* or “artificial limb” (mesh) 3 “residual limb” or stump 4 amputee (mesh) or amputa* 5 1 and 2 6 1 and 3 7 1 and 4 https://doi.org/10.33137/cpoj.v8i1.43073 4 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 figure 1: prisma flow diagram. countries reported five studies reported data from the usa; three from seattle,24-26 one from ohio,27 and one from indianapolis.28 two studies reported data from the uk; one from london,29 and one from oxford.5 one study reported data from hiroshima, japan.30 study method all eight studies used a quantitative approach. specifically, four studies used a randomized control trial methodology.25,27,28,30 one study used a comparative study methodology,5 whilst another used a repeated measure pilot study methodology.29 one study used a structured observation study design,26 and another utilized an observational experimental methodology.24 study sample sizes a total of 96 participants were included across the eight studies, 62 participants with a transtibial amputation from seven studies,5,24-27,29,30 25 participants with a transfemoral amputation from four studies,5,28-30 2 participants with a bilateral amputation from two studies,27,29 and 7 participants without an amputation from one study.30 one study tested 5 participants with a transfemoral amputation and 2 participants with a transtibial amputation alongside 7 participants without an amputation as a control group for comparison.30 another study involved a participant with a bilateral amputation to conduct a blind test of two interventions simultaneously, allowing for immediate comparison of results.27 thematic analysis within the broad scope of reviewing thermoregulation and thermal discomfort in lower-limb prosthetics, four themes emerged. theme 1 – the effect of activity on residual limb skin temperature, and making a comparison to thermal discomfort as a related issue, theme 2 comparing the effect of a prosthetic cooling intervention to a regular noncooling prosthetic design on thermoregulatory and subjective measures, theme 3 – comparing thermoregulatory and subjective responses between participants with a lower-limb amputation and control participants in a hot environment, theme 4 – measuring residual limb skin temperature to verify out-of-lab thermal comfort studies. theme 1: klute et al. investigated the impact of increasing activity on residual limb skin temperature in lower-limb amputees, commenting on thermal discomfort decreasing quality of life as a result of the increased temperature. the author highlighted the need for developing a cooling intervention to improve thermal comfort and promote prosthetic adherence by reducing local perspiration.24 segal et al. reported an increase in mean residual limb skin temperature and core temperature during exercise testing in a cold environment. perceived thermal discomfort levels were elevated on the residual limb compared to the contralateral limb post-exercise.26 diment et al. reported both residual and contralateral limbs cooling during exercise and no significant difference in skin temperature between the limbs. thermal discomfort was greater on the amputated side compared to the contralateral side.5 theme 2: three studies25,27,28 tested a prosthetic cooling intervention against a regular non-cooling prosthesis and reported the differences in residual limb skin temperature and perspiration levels. two studies compared the thermoregulatory measures against subjective responses including thermal comfort, thermal sensation and prosthetic satisfaction.25,28 klute et al. compared a dynamic air exchange (dae) prosthetic socket to a total surface-bearing suction socket (suction). no significant difference in residual limb skin temperature was reported between the groups however a significant reduction in perspiration was observed in the dae results. subjective measures revealed better residual limb health and a reduction in heat and records identified from databases: (n=3905) medline (n=866) embase (n=2516) cochrane (n=253) cinahl (n=225) psycinfo (n=45) records removed before screening: duplicate records removed (n =1293) id e n ti fi c a ti o n records screened (n = 2612) records excluded (n = 2560) reports sought for retrieval (n = 52) reports not retrieved (n = 0) reports assessed for eligibility (n = 52) studies included in review (n = 8) s c re e n in g in c lu d e d identification of studies via databases and registers reports removed for ineligibility (n = 44) https://doi.org/10.33137/cpoj.v8i1.43073 5 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 sweating when wearing the dae prosthesis, however, it was found to be more frustrating than the suction prosthesis.25 gnyawali et al. compared a vented linersocket system (vs, ossur) with a seal-in liner and nonvented socket (nvs, ossur). during activity, relative socket humidity was reduced in the (vs, ossur) compared to the (nvs, ossur). however, no significant difference in insocket temperature between the two systems was reported. there was also no significant difference between subjective measure reports on suspension, comfort or stability between the two systems.28 wernke et al. compared a smarttemp phase change material liner against a placebo liner and reported a reduction in residual limb skin temperature and local perspiration within the smarttemp group.27 theme 3: hasegawa et al. compared both thermoregulatory and subjective responses between participants with lower-limb amputation and a control group of participants without an amputation, under the same exercise conditions in a hot environment. core temperature increased throughout exercise testing however no difference was observed between the groups. skin temperature also increased throughout both groups but tended to be higher in the group of participants with a lower limb amputation. local sweat rate increased for both groups however a difference between the amputated and contralateral limb was observed in the group of participants with a lower-limb amputation, with a higher local sweat rate being observed on the contralateral side. thermal sensation was lower in the group of participants with a lower limb amputation. thermal comfort decreased for both groups during exercise however it remained higher within the group of participants with a lower limb amputation.30 theme 4: williams et al. compared residual limb skin temperature measurements during an exercise test in a controlled environment to measurements obtained during out-of-lab testing of participants engaging in daily activities. results revealed that on average, residual limb skin temperatures were higher in out-of-lab testing.29 discussion to the best of the author’s knowledge, this scoping review represents the first evaluation of literature regarding thermoregulatory measures – such as skin temperature, core temperature or sweating for addressing thermal discomfort in lower-limb prosthetics. notably, a previous literature review has been undertaken which explored the prevalence of heat and perspiration discomfort within prosthetics.3 the main findings of this review include inconsistent findings on the role of skin temperature in thermal discomfort, raising questions about its significance as a measurable parameter. in addition, thermal discomfort was often linked to sweat accumulation rather than skin temperature changes. sweat accumulation in the socket may be a major discomfort due to the involvement of wet skin discomfort and mechanoreceptor activation. people with lower-limb amputation may compensate for heat dissipation with increased sweating and blood flow in other body areas. review scope and objectives the findings of this review address the utilization of thermoregulatory measures in testing to investigate thermal-related issues in lower limb prosthetics, to potentially identify novel directions for experimental design in future research. despite the importance of addressing thermal discomfort in lower-limb prosthetics and its consequent effect on user satisfaction and quality of life, limited evidence is available at present on how to address the issue. this may be due to a lack of understanding of the effects a prosthesis has on the thermoregulatory processes, how prosthetic liners or sockets interact with the skin and how thermal discomfort is perceived by people with an amputation. skin temperature measurements when addressing the issue of thermal discomfort in lowerlimb prosthetics, researchers have measured skin temperature changes at the residual limb as many people with an amputation report elevated skin temperatures and a consequent increase in perspiration to be a cause of discomfort.3,31-35 all the studies included in this review measured the change in residual limb skin temperature in response to activity. this may be indicative of residual limb skin temperature being the most widely accepted measurement when carrying out experimental research into lower-limb prosthetic thermal discomfort. four studies reported a significant increase in residual limb skin temperature during activity.24,26,29,30 both klute et al. and wernke et al. reported an overall increase in residual limb skin temperature during activity, however, no significant difference between the dae socket and smarttemp liner designs was observed compared to the conventional socket and liner.25,27 gynawali et al. reported no significant change in residual skin temperature post-exercise.28 diment et al. reported a slight decrease in residual limb skin temperature on average post-exercise.5 the conflict in the results may allude to whether or not residual limb skin temperature may be the prime factor in thermal discomfort. perspiration measurements as a reported consequence of an increased thermal environment at the bdi, lower-limb prosthetic users also commonly report increased perspiration within the socket leading to sweat build-up. this has directed research towards improving socket and liner designs to reduce perspiration levels. https://doi.org/10.33137/cpoj.v8i1.43073 6 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 table 3: data extraction table. author; year; location; sample size study design participant demographic: amputation; age measurement tools utilised temperature/perspiration outcomes qualsyst quality threshold score diment et al. 2019; oxford; 305 comparative study. tf 11, tt 19; 23-65yr clinical infrared thermometer. 6-point heat and sweat discomfort scale. primary: i). skin temperature change. findings: anova test showed that on average, the skin on both legs cooled during exercise (0.085°c/min, p = 0.002). there was no significant difference in skin temperature between the amputated and contralateral limbs. a significant difference in skin temperature was observed between the front and back of the leg with the back being significantly warmer post-exercise. secondary: i). variation in temperature response between amputated and contralateral limb. findings: temperature changes were small, with a large standard deviation of approximately 0.5°c on each limb. the average deviation between the 3 measurements taken at each location was 0.021°c. 0.86 gnyawali et al. 2023; indianapolis; 928 randomised controlled trial. tf 46.5yr ± 14.03 vented linersocket system (vs, ossur). non-vented socket (nvs, ossur). data logger system with humidity and temperature sensors. 10-point perceived sweat scale. class survey primary: i). skin humidity change. findings: no meaningful changes were observed for both sound and a residual limb during baseline testing. humidity significantly increased during activity compared to the baseline on the residual limb compared to the sound side. the relative residual limb humidity was significantly lower during activity with the use of the vs compared to the nvs. ii). in-socket/skin temperature change. findings: no significant increase between the (nvs vs vs). there was also no significant difference in skin temperature between the residual and sound limbs. secondary: i). perceived sweat score findings: significantly lower in the vs group compared to the nvs group. 0.83 klute et al. 2016; seattle; 525 randomised control trial. tt; 18-70yr dae socket. tsb suction socket. two thermistor sensors. gravimetry. prosthesis evaluation questionnaire. custom, selfreporting questionnaire. primary: i). residual limb skin temperature change. findings: no difference between the two prostheses was observed during the rest-walk-rest protocol. ii). accumulated/expelled perspiration. findings: the dae prosthesis accumulated 1.09 ± 0.90g and expelled 0.67 ± 0.38g of perspiration. the suction prosthesis accumulated 0.97 ± 0.75g of perspiration. secondary: i). residual limb skin temperature increased ~3°c for both prostheses during the 30-minute treadmill walk. 0.79 hasegawa et al. 2020; hiroshima; 1430 randomised controlled trial. tf 5, tt 2, c 7; lla (36.4yr ± 4.4); c (31.7yr ± 7.8) a rectal thermistor. thermistor sensors. body surface area dubois formula. sweat capsule and a local sweat meter. laser doppler blood flow meter. primary: i). rectal temperature change. findings: increased throughout the test however no difference was observed between the groups. ii). skin temperature change. findings: increased throughout the test in both groups however intended to be higher in the lla group. iii). lsr change. findings: increased throughout the test for both groups at the thigh. a difference between the left and right leg was not observed in the c group. in the lla group, lsr was significantly greater on the non-amputated side compared to the amputated side. the total sweat rate was also significantly higher in the lla group. 0.73 wernke et al. 2015; ohio, 1627 double-blind randomised, crossover design. tt (1 bl); 3278yr smarttemp liner and placebo liner. 4 thermocouples. gravimetry. primary: i). skin temperature change. findings: the mean increase after activity was 0.2°c higher for the placebo liner compared to the smarttemp liner. ii). accumulated perspiration. findings: significantly reduced when wearing the smarttemp liner for 12 participants post-activity secondary: i). inclusion of a bilateral amputee for testing both treatments in the same activity. skin temperature increased during activity on both limbs, however, skin temperatures associated with the smarttemp liner were lower compared to the placebo liner. 0.68 https://doi.org/10.33137/cpoj.v8i1.43073 7 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 four of the eight included studies measured perspiration within the socket during testing. klute et al., wernke et al. and gnyawali et al. all reported an increase in sweat or humidity at the bdi during exercise.25,27,28 wernke et al. also disclosed that 4 of the 16 subjects did not sweat in either of the tested liners during exercise.27 hasegawa et al. reported an increase in local sweat rate at the thigh, with the prosthesis removed for the group of participants with an amputation.30 prosthetic interventions for thermal-related issues prosthetic technologies have been engineered to mitigate heat and perspiration, serving as a targeted intervention. such interventions include sockets which incorporate cooling mechanisms such as heat pumps or cooling channels and liners composed of phase change materials which can store and release heat, as presented in table 3.2,27,36 klute et al., wernke et al. and gnyawali et al. conducted studies assessing the efficacy of an intervention device in contrast to conventional prosthetic components. their research aimed to elucidate the effects of these interventions on thermoregulatory parameters during exercise.25,27,28 klute et al. and gynawali et al. both compared a conventional socket to an intervention socket, designed to expel accumulated perspiration and discussed changes in residual limb skin temperature, sweating and subjective measures. wernke et al. compared a placebo liner to a smarttemp liner composed of phase change material.27 as previously discussed, all three studies reported a significant reduction in perspiration levels during activity. however, no significant change in skin temperature was recorded. participants also rated perceived limb perspiration to be lower when using the intervention sockets compared to the standard sockets.25,28 the outcomes from these studies suggest that prosthetic interventions targeting heat and perspiration reduction were significantly more table 3 (continued): data extraction table. author; year; location; sample size study design participant demographic: amputation; age measurement tools utilised temperature/perspiration outcomes qualsyst quality threshold score segal et al. 2016; seattle; 826 structured observational study tt; 31-64yr four thermistor sensors. 11-point likert psychometric scale. ingestible temperature sensor. polar heart rate monitor. primary: i). residual limb skin temperature change. findings: mean temperature increased from 30.6 °c ± 2.6°c at rest1 to 34.5°c ± 1.7°c at the end of exercise2. temperature increased by 2.7°c at the end of exercise1 compared to the end of rest1, followed by an insignificant decrease of -0.3°c after rest 2. after exercise2, a further increase of 1.5°c occurred compared to rest2 followed by insignificant cooling of -0.4°c at the end of rest3. ii). perceived thermal discomfort. compared with rest1, ptc across all regions increased for exercise1 and exercise2. across bouts, residual limb ptc was higher than the intact limb. secondary: i). core temperature change. findings: increased by 0.9°c on average during exercise1 and remained elevated throughout the remainder of the testing session. 0.68 klute et al. 2014; seattle; 924 observational study. tt; 28-73yr 16 thermistor sensors. primary: i) skin temperature change. findings: initial 30-minute rest: avg temp 31°c ± 1.5°c. post30-minute treadmill walk: avg temp 34.1°c ± 1.3°c. final 60minute seated rest: avg temp 33.2°c ± 1.2°c. 0.64 williams et al. 2018; london; 529 repeated measure pilot study. ul tf 3, ul tt 1, bl 1 (r tf, l tt); 19-42yr 12 thermistor sensors. arduino microcontroller connected to a real-time clock and an sd card. primary: i). residual limb skin temperature change. findings: phase one increase after donning the prosthesis. exercise one: 4 participants showed an increase. 1 participant displayed no notable change. final rest phase: all participants showed a further increase. phase two: all participants showed a higher temperature relative to phase one. however, it was noted that this was unsurprising due to the difference in ambient temperature between the two tests. a maximum change in was observed in participant 5 with an increase of 5.1°c. 0.50 abbreviations: tt: transtibial amputee, tf: transfemoral amputee, bl: bilateral, ul: unilateral, lla: lower-limb amputee, c: control (person without an amputation), ptc: perceived thermal comfort, lsr: local sweat rate, class: comprehensive lower limb amputee survey, dae: dynamic air exchange, tsb: total surfacebearing. https://doi.org/10.33137/cpoj.v8i1.43073 8 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 proficient in lowering perspiration levels compared to their impact on residual limb temperature. impact of amputation on heat dissipation the process of amputation, by nature, reduces the surface area of the human body. body surface area is reduced by approximately 21% for a transfemoral amputation and 9% for a transtibial amputation.35 this may impair a person with an amputation's ability to dissipate heat as there is less area for convection, radiation, evaporation and conduction to occur.3 hasegawa et al. measured local sweat rate, skin blood flow at the thigh, and total sweat rate in both participants with an amputation and control participants without an amputation. in the control group, both skin blood flow and local sweat rate increased symmetrically across both limbs during exercise. in the group of participants with an amputation, skin blood flow measurements were significantly higher in the contralateral limb compared to the residual limb during exercise. similarly, local sweat rate was significantly higher on the contralateral limb compared to the residual limb. despite these differences, the total amount of local sweat rate across both limbs did not differ between the two groups. however, the total sweat rate was significantly higher in the group of participants with an amputation. hasegawa et al. suggested that despite the lower body surface area for heat dissipation in people with an amputation, the overall heat dissipation was similar between the two groups. this was likely due to compensatory sweating on the torso and contralateral limb. they also inferred that increased blood flow on the contralateral side might indicate compensatory vasodilation on the limb with an amputation.30 this was supported by diment et al. who found that the contralateral limb was typically warmer than the residual limb, even with the prosthesis donned when measuring skin temperature during exercise.5 the consistency in these findings indicates a compensatory role of heat dissipation following amputation.30 subjective measures for thermal discomfort both socket and thermal comfort and discomfort are inherently subjective, difficult to distinguish and vary from individual to individual, posing challenges to reproducibility and reliability as a measurable parameter.37 however, within the domain of prosthetics, it holds significant importance for researchers as it aids the identification of specific scenarios or environmental conditions associated with increased thermal discomfort. thermal comfort and discomfort are commonly assessed through subjective measure questionnaires, whereby users report on comfort, heat levels, perspiration, suspension and functionality of their prosthesis. five of the included studies recorded subjective measures.5,25,26,28,30 segal et al., diment et al. and hasegawa et al. all measured thermal comfort or discomfort as a direct outcome.5,26,30 all three studies agreed that thermal discomfort increased at the residual limb with exercise. when comparing thermal discomfort between the residual and contralateral limb, both segal et al. and diment et al. reported heightened thermal discomfort at the residual limb compared to the contralateral limb.5,26 parallel to this, when comparing a group of participants with an amputation to a control group without an amputation, hasegawa et al. reported an increase in thermal discomfort during exercise across all limbs in both groups. interestingly, thermal discomfort was significantly lower on average in the group of participants with an amputation than in the control group. this may, however, be a result of testing being conducted with the prosthesis removed, suggesting people with an amputation may be more tolerant to thermal discomfort as the issue is experienced much more often compared to a person without an amputation.30 correlation between thermoregulatory parameters and subjective measures to gain a better understanding as to what may be causing thermal discomfort for people with a lower limb amputation, it is important to draw links between the subjective responses and thermoregulatory measurements gathered during testing. klute et al. discussed a general increase in residual limb skin temperature for both intervention and conventional sockets tested, although, no significant difference was seen between the two during exercise. the intervention socket significantly reduced the amount of accumulated sweat compared to the conventional socket. subjects reported that the intervention socket reduced heat and sweat. they also “strongly agreed” with the statement that the intervention socket kept their residual limb at a more comfortable temperature whereas they “slightly disagreed” when wearing the standard socket.25 segal et al. reported a significant increase in skin temperature during exercise, coinciding with an increase in thermal discomfort. thermal discomfort tended to be higher at the residual limb compared to the contralateral limb.26 hasegawa et al. reported an increase in skin temperature post-exercise in both groups of participants with an amputation and control groups along with an increase in local sweat rate and thermal discomfort.30 gnyawali et al. reported no significant increase in residual limb skin temperature for both intervention and conventional sockets throughout testing. a significant increase in residual limb humidity measurements was observed during exercise. the perceived sweat score was reported significantly lower for subjects wearing the intervention compared to the conventional socket, however, the comprehensive lower limb amputee survey (class), used when assessing prosthetic fit, showed no significant difference between the groups for suspension, comfort or stability.28 diment et al reported a decrease in residual limb skin temperature during exercise, however, thermal discomfort was still experienced, more so on the amputated side.5 https://doi.org/10.33137/cpoj.v8i1.43073 9 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 an intriguing link between thermoregulatory parameters and subjective measures was made. both klute et al. and gnyawali et al. reported a decrease in thermal discomfort when subjects were wearing a socket designed to reduce heat and perspiration, however, participants could not be blinded to the intervention sockets. both interventions also reduced the amount of accumulated sweat within the socket. however, klute et al. reported no significant difference in the increase of residual limb temperature between the two sockets. gynawali et al. also reported the lack of a significant increase in skin temperature for both sockets.25,28 considering the reduction in thermal discomfort, coinciding with a reduction in accumulated sweat, without any significant changes in residual limb skin temperature, suggests that skin temperature may not be the primary instigator for lower-limb thermal discomfort. furthermore, diment et al. concluded that skin temperature does not explain the thermal discomfort experienced by the prosthetic users in their study.5 however, it is noteworthy that both hasegawa et al. and segal et al. reported an elevation in thermal discomfort alongside an increase in residual limb skin temperature.26,30 behavioral thermoregulation shlader et al. explored behavioral thermoregulation as the most favored and effective form of temperature regulation. they demonstrated that eliciting this behavior does not require a temperature change; rather, thermal sensation and discomfort alone suffice as triggers.38 discussing the findings of diment et al., even in the absence of a rise in residual limb skin temperature, the presence of thermal discomfort alone during exercise may prompt the person with an amputation to remove their prosthesis as a behavioral thermoregulatory response.5 future research directions these findings pose the question of how thermal discomfort is perceived by a person with an amputation when wearing a prosthesis. an avenue for future research may be to explore the effects of prolonged skin wetness due to sweat accumulation at the bdi. detecting skin wetness has been shown to impact thermal comfort, and therefore thermoregulatory behavior which makes it a crucial mechanism for thermal adaptation.39 humans detect skin wetness through multisensory integration between thermal and mechanosensory inputs.40 under normal thermoregulatory circumstances, temperature sensation and thermal discomfort are linked to skin surface temperature in cold environments. in warm environments, on the other hand, thermal discomfort is more related to sweating than skin temperature, as skin temperature is maintained at a favorable level due to evaporative cooling due to sweating. it is suggested that one factor for this thermal discomfort is the level of wetness over the skin surface.41 limitations a limitation of this study was the inclusion of low-quality articles due to the low number of included literature. as aforementioned, only two articles achieved a strong qualsyst score of >0.80, two articles achieved a good qualsyst score of 0.71-0.79 and four articles achieved an adequate qualsyst score of 0.5-0.7. referring to the qualsyst scores in the extraction table, five of the included articles scored below the suggested qualsyst cut-off score of 0.75, and if the score was used as an exclusion criterion instead of an outcome measure as per this review, these articles would have been removed. conclusion this scoping review evaluated the current literature concerning thermoregulatory measures associated with thermal discomfort in lower-limb prosthetics. whilst literature has explored the prevalence of heat and perspiration discomfort within prosthetics, this review investigated the utilization of thermoregulatory measures for addressing thermal-related issues. although numerous studies have tested thermal discomfort in lower-limb prosthetics, there may be a lack of understanding of how donning a prosthesis affects thermoregulation from a physiological point of view. measuring the change in residual limb skin temperature has been the focal point for discussing thermal discomfort in lower limb prosthetics, with several studies reporting elevated skin temperatures during exercise. however, conflicting results reporting a reduction or no change in skin temperature pose questions about the significance of the parameter as the prime factor in lower-limb prosthetic thermal discomfort. another significant aspect contributing to prosthetic thermal discomfort is perspiration at the bdi leading to the accumulation of unevaporated sweat. prosthetic interventions designed to reduce heat and perspiration at the bdi show promise for reducing perspiration and sweat accumulation, consequently improving thermal comfort, emphasizing the importance of technological advancements in this area. however, little evidence emerged regarding the efficacy of these interventions for reducing residual limb skin temperature, with a lack of correlation between skin temperature measurements and thermal discomfort at the bdi. whilst progress has been made to combat and further understand lower limb prosthetic thermal discomfort, both through design and research, a knowledge gap remains. in particular, regarding the perception of thermal discomfort and the involvement of not only skin temperature but also https://doi.org/10.33137/cpoj.v8i1.43073 10 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 the effects of prolonged skin wetness due to unevaporated sweat. this may be a pivotal parameter for further managing thermal discomfort, increasing usage and improving the quality of life for lower-limb prosthetic users. acknowledgements the author would like to thank the esrpc centre for doctoral training in prosthetics & orthotics for its support. declaration of conflicting interests the author has no conflicts of interest to declare. authors’ contribution rowan edwards conceived the idea, conducted the research, and drafted the manuscript, while arjan buis and laura murray provided supervision. all authors actively participated in the discussion of results and contributed to the manuscript's revision. all authors have read and approved the final version of the manuscript. sources of support epsrc centre for doctoral training in prosthetic & orthotics – grant number: ep/s02249x/1. references 1.mcdonald cl, westcott-mccoy s, weaver mr, haagsma j, kartin d. global prevalence of traumatic non-fatal limb amputation. prosthet orthot int. 2021;45(2):105-14. doi: 10.1177/ 0309364620972258 2.matthews d, sukeik m, haddad f. return to sport following amputation. j sports med phys fitness. 2014;54(4):481-6 3.ghoseiri k, safari r. prevalence of heat and perspiration discomfort inside prostheses: literature review. j rehabil res dev. 2014;51(6):855-68. doi: 10.1682/jrrd.2013.06.0133 4.klute g, rowe g, mamishev a, ledoux w. the thermal conductivity of prosthetic sockets and liners. prosthetorthot int. 2007;31(3):292-9. doi: 10.1080/03093640601042554 5.diment le, thompson ms, bergmann jh. comparing thermal discomfort with skin temperature response of lower-limb prosthesis users during exercise. clin biomech (bristol). 2019;69:148–155. doi: 10.1016/j.clinbiomech.2019.07.020 6.bartolomeu n, gonzalez j, valentim f, e silva mr, ramos n, jacinto j. improvement in quality of life of transfemoral amputees: comparison between 2 types of transfemoral sockets and their influence on functionality and user comfort-a case report. prosthet orthot int. 2024;48(3):344-347. doi: 10.1097/pxr. 0000000000000286 7.hachisuka k, matsushima y, ohmine s, shitama h, shinkoda k. moisture permeability of the total surface bearing prosthetic socket with a silicone liner: is it superior to the patella-tendon bearing prosthetic socket? j uoeh. 2001;23(3):225-32. doi: 10.7888/ juoeh.23.225 8.arens ea, zhang h. the skin's role in human thermoregulation and comfort. 2006. woodhead publishing ltd. https://escholarship.org/content/qt3f4599hx/qt3f4599hx.pdf 9.levy sw. skin problems of the leg amputee. prosthet orthot int. 1980;4(1):37-44 10.henao sc, cuartas-escobar s, ramírez j. coefficient of friction measurements on transfemoral amputees. biotribology. 2020;22:100126. doi: 10.1016/j.biotri.2020.100126 11.werner j. system properties, feedback control and effector coordination of human temperature regulation. eur j appl physiol. 2010;109:13-25. doi: 10.1007/s00421-009-1216-1 12.benzinger t. peripheral cold-and central warm-reception, main origins of human thermal discomfort. proc natl acad sci usa . 1963;49(6):832.doi: 10.1073/pnas.49.6.832 13.nagashima k, tokizawa k, marui s. thermal comfort. handb clin neurol. 2018;156:249-60. doi: 10.1016/b978-0-444-639127.00015-1 14.hensen jlm. on the thermal interaction of building structure and heating and ventilating system [phd thesis]. eindhoven: technische universiteit eindhoven; 1991. doi:10.6100/ir353263 15.thermal environmental conditions for human occupancy [internet]. ansi/ashrae standard 55-2004. atlanta (ga): american society of heating, refrigerating and air-conditioning engineers, inc.; 2004 [cited 2025 mar 25]. available from: https://www.ditar.cl/archivos/normas_ashrae/t0080ashrae55-2004-thermalenviromcondiho.pdf 16.djongyang n, tchinda r, njomo d. thermal comfort: a review paper. renew sustain energy rev. 2010;14(9):2626-2640. doi: 10.1016/j.rser.2010.07.040 17.frank sm, raja sn, bulcao cf, goldstein ds. relative contribution of core and cutaneous temperatures to thermal comfort and autonomic responses in humans. j appl physiol (1985). 1999;86(5):1588-93. doi: 10.1152/jappl.1999.86.5.1588 18.harden rn, gagnon cm, gallizzi m, khan as, newman d. residual limbs of amputees are significantly cooler than contralateral intact limbs. pain pract. 2008;8(5):342-7. doi: 10.1111/j.1533-2500.2008.00216.x 19.lang m, müller a. climate socket-focusing on thermal comfort in the prosthetic socket. inabstract book of ispo world congress, lyon, france 2015 jun (pp. 22-25). 20.fukuhara k, mikami y, hasegawa h, nakashima d, ikuta y, tajima f, et al. thermoregulatory responses in persons with lowerlimb amputation during upper-limb endurance exercise in a hot and humid environment. prosthet orthot int. 2021;45(5):401-9. doi: 10.1097/pxr.0000000000000030 21.cutti ag, perego p, fusca mc, sacchetti r, andreoni g. assessment of lower limb prosthesis through wearable sensors and thermography. sensors (basel, switzerland). 2014;14(3):5041-55. doi: 10.3390/s140305041 22.kmet lm. standard quality assessment criteria for evaluating primary research papers from a variety of fields [internet]. edmonton: alberta heritage foundation for medical research; 2004 [cited 2024 april 22]. available from: https://era.library.ualberta.ca/items/48b9b989-c221-4df6-9e35af782082280e 23.lee l, packer tl, tang sh, girdler s. self‐management education programs for age‐related macular degeneration: a systematic review. australas j ageing. 2008;27(4):170-6. doi: 10.1111/j.1741-6612.2008.00298.x https://doi.org/10.33137/cpoj.v8i1.43073 https://escholarship.org/content/qt3f4599hx/qt3f4599hx.pdf https://www.ditar.cl/archivos/normas_ashrae/t0080ashrae-55-2004-thermalenviromcondiho.pdf https://www.ditar.cl/archivos/normas_ashrae/t0080ashrae-55-2004-thermalenviromcondiho.pdf https://era.library.ualberta.ca/items/48b9b989-c221-4df6-9e35-af782082280e https://era.library.ualberta.ca/items/48b9b989-c221-4df6-9e35-af782082280e 11 edwards r, murray l, buis a. the role of human thermoregulation in thermal discomfort in lower-limb prosthetics: a scoping review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.3. https://doi.org/10.33137/cpoj.v8i1.43073 canadian prosthetics & orthotics journal issn: 2561-987x thermoregulation and thermal discomfort in lower-limb prosthetics: a scoping review edwards et al., 2025 24.klute gk, huff e, ledoux wr. does activity affect residual limb skin temperatures? clin orthop relat res. 2014;26. doi: 10.1007/s11999-014-3741-4 25.klute gk, bates kj, berge js, biggs w, king c. prosthesis management of residual-limb perspiration with subatmospheric vacuum pressure. j rehabil res dev. 2016;53(6):721-8. doi: 10.1682/jrrd.2015.06.0121 26.segal ad, klute gk. residual limb skin temperature and thermal comfort in people with amputation during activity in a cold environment. j rehabil res dev. 2016;53(5):619-28. doi: 10.1682/jrrd.2015.03.0053 27.wernke mm, schroeder rm, kelley ct, denune ja, colvin jm. smarttemp prosthetic liner significantly reduces residual limb temperature and perspiration. j prost orthot. 2315;27(4):134-9. doi:10.1097/jpo.0000000000000070 28.gnyawali sc, denune ja, hockman b, kristjánsdóttir jv, ragnarsdóttir ms, timsina lr, et al. moisture mitigation using a vented liner and a vented socket system for individuals with transfemoral amputation. sci rep. 2023;13(1):16557.doi: 10.1038/s41598-023-43572-2 29.williams rj, takashima a, ogata t, holloway c. a pilot study towards long-term thermal comfort research for lower-limb prosthesis wearers. prosthet orthot int. 2019;43(1):47-54. doi: 10.1177/0309364618791604 30.hasegawa h, makino h, fukuhara k, mikami y, kimura h, adachi n. thermoregulatory responses of lower limb amputees during exercise in a hot environment. j therm biol. 2020;91. doi: 10.1016/j.jtherbio.2020.102609 31.hagberg k, brånemark r. consequences of non-vascular transfemoral amputation: a survey of quality of life, prosthetic use and problems. prosthet orthot int. 2001;25(3):186-94. doi: 10.1080/03093640108726601 32.legro mw, reiber g, del aguila m, ajax mj, boone da, larsen ja, et al. issues of importance reported by persons with lower limb amputations and prostheses. j rehabil res dev. 1999;36(3):15563. 33.meulenbelt he, geertzen jh, jonkman mf, dijkstra pu. skin problems of the stump in lower limb amputees: 2. influence on functioning in daily life. acta derm-venereol. 2011;91(2):178-82. doi: 10.2340/00015555-1023 34.gholizadeh h, osman na, eshraghi a, ali s, razak n. transtibial prosthesis suspension systems: systematic review of literature. clin biomech. 2014;29(1):87-97. doi: 10.1016/j. clinbiomech.2013.10.013 35.colangelo pm, welch dw, rich ds, jeffrey lp. two methods for estimating body surface area in adult amputees. am j hos pharm. 1984;41(12):2650-5. 36.webber cm, davis bl. design of a novel prosthetic socket: assessment of the thermal performance. j biomech. 2015;48(7):1294-9. doi: 10.1016/j.jbiomech.2015.02.048 37.wang j, wang z, de dear r, luo m, ghahramani a, lin b. the uncertainty of subjective thermal comfort measurement. energy build. 2018;181:38-49. doi: 10.1016/j.enbuild.2018.09.041 38.schlader zj, simmons se, stannard sr, mündel t. the independent roles of temperature and thermal perception in the control of human thermoregulatory behavior. physiol behav. 2011;103(2):217-24. doi: 10.1016/j.physbeh.2011.02.002 39.filingeri d. why wet feels wet? an investigation into the neurophysiology of human skin wetness perception [phd thesis]. loughborough: loughborough university; 2014 40.filingeri d, havenith g. human skin wetness perception: psychophysical and neurophysiological bases. temperature. 2015;2(1):86-104. doi: 10.1080/23328940.2015.1008878 41.fukazawa t, havenith g. differences in comfort perception in relation to local and whole body skin wettedness. eur j appl physiol. 2009;106(1):15-24. doi: 10.1007/s00421-009-0983-z appendix alberta foundation qualsyst tool. criteria yes (2) partial (1) no (0) n/a 1 question / objective sufficiently described? 2 study design evident and appropriate? 3 method of subject/comparison group selection or source of information/input variables described and appropriate? 4 method of subject/comparison group selection or source of information/input variables described and appropriate? 5 if interventional and random allocation was possible, was it described? 6 if interventional and blinding of investigators was possible, was it reported? 7 if interventional and blinding of subjects was possible, was it reported? 8 outcome and (if applicable) exposure measure(s) well defined and robust to measurement/misclassification bias? means of assessment reported? 9 sample size appropriate? 10 analytic methods described/justified and appropriate? 11 some estimate of variance is reported for the main results? 12 controlled for confounding? 13 results reported in sufficient detail? 14 conclusions supported by the results? the grey highlights indicate that the ‘n/a’ box cannot be checked for that criteria question. a summary score is calculated for each paper by summing the total score obtained across relevant items and dividing by the total possible score (i.e.: 28 – (number of “n/a” x2)).22 https://doi.org/10.33137/cpoj.v8i1.43073 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 1 2025 review article williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i1.43717 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 review article wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers williams-reid h1, johannesson a2, buis a1* 1 department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. 2 össur clinics emea, stockholm, sweden. introduction 1: overall rationale, aims, and objectives a wound is defined as damage to biological tissue,1 encompassing various forms, including deep tissue injuries associated with prolonged prosthesis use and the surgical site resulting from amputation. the wound healing process is a complex biological process involving four interlinked phases: hemostasis, inflammation, proliferation, and tissue remodeling.2-4 this process requires intricate cellular coordination, rendering it vulnerable to impairment that can result in a stalled (also known as chronic or non-healing) wound.5 amputation surgical sites, however, do not always heal optimally, instead experiencing complications such as infection, pain, wound dehiscence, stitch abscesses, tissue necrosis, and poor residual limb formation.6,7 these open access abstract background: poor post-amputation healing delays prosthetic fitting, adversely affecting mortality, quality of life, and cardiovascular health. current residual limb assessments are subjective and lack standardized guidelines, emphasizing the need for objective biomarkers to improve healing and prosthesis readiness assessments. objective(s): this review aimed to identify predictive, diagnostic, and indicative chemical biomarkers of healing of the tissues and structures found in the residual limbs of adults with amputation. methodology: this scoping review followed joanna briggs institute (jbi) and prisma-scr guidelines. searches using the terms “biomarkers,” “wound healing,” and “amputation” were performed across web of science, ovid medline, ovid embase, scopus, cochrane, pubmed, and cinahl databases. inclusion criteria were: 1) references to chemical biomarkers and healing; 2) residuum tissue healing; 3) repeatable methodology with ethical approval. included articles were evaluated for quality of evidence (qualsyst tool) and level of evidence (jbi classification). sources were categorized by study (e.g., randomized controlled trial or bench research), wound (diabetic, amputation, other), and model (human, murine, other) type. chemical biomarkers repeated across study categories, and quantification methods were reported on. findings: from 3,306 titles and abstracts screened, 646 underwent full-text review, and 203 met the criteria for data extraction, with 76% classified as strong quality. 38 chemical biomarkers were identified across 4 to 50 sources, with interleukins (predictive, indicative, and diagnostic) and hba1c (predictive) most prevalent, appearing in 50 and 48 sources, respectively. other biomarkers included predictive blood markers (e.g., cholesterol, white blood cell counts), indicative growth factors, bacteria presence (predictive), proteins (predictive, indicative, and diagnostic, e.g., matrix metalloproteinases), and cellular markers (indicative and diagnostic, e.g., ki-67, alpha-smooth muscle actin [α-sma]). conclusion: predictive biomarkers identify comorbidities that may hinder healing, aiding in preamputation risk assessment for poor recovery. indicative biomarkers monitor key biological healing processes, such as angiogenesis (the formation of new blood vessels), wound contraction, and inflammation. diagnostic biomarkers provide direct insights into tissue composition and cellular-level healing. integrating these biomarkers into post-amputation assessments enables continuous monitoring of the healing process while accounting for comorbidities, enhancing the objectivity of post-surgical healing management and ensuring more effective, personalized rehabilitation strategies. article info received: july 12, 2024 accepted: february 12, 2025 published: february 21, 2025 citation williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1 .43717 keywords amputation; scoping review; wound healing; surgical site healing; chemical biomarkers; chemical markers of healing; residuum healing; residual limb healing; wound management; early prosthetic rehabilitation please refer to the end of the article for a list of abbreviations & acronyms. * corresponding author: professor arjan buis, phd department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. e-mail: arjan.buis@strath.ac.uk orcid id: https://orcid.org/0000-0003-3947-293x journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 1, article no.1. 2025 https://doi.org/10.33137/cpoj.v8i1.43717 https://doi.org/10.33137/cpoj.v8i1.43717 https://doi.org/10.33137/cpoj.v8i1.43717 mailto:arjan.buis@strath.ac.uk https://orcid.org/0000-0003-3947-293x https://jps.library.utoronto.ca/index.php/cpoj/index 2 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 complications stall healing and, in severe cases, necessitate revision surgeries or re-amputation.6 despite their critical role in preventing complications like reamputation, wound healing assessments remain subjective.8 this is particularly significant for individuals with major lower limb amputation, defined as amputation through or proximal to the ankle, whose readiness for prosthetic rehabilitation depends on the health and healing of their residual limb. early prosthetic fitting improves mobility, ambulation, and daily functioning,9-11 whilst increased costs and elevated three-year post-amputation mortality rates are associated with delays or failure to provide timely prosthetic interventions.10,11 however, current evaluations of the residual limb post-amputation rely on clinical judgement, lacking standardized guidelines or objective metrics.8,12,13 while factors like wound healing, pain management, and limb volume are considered, they are not consistently quantified. additionally, debates over rehabilitation practices promoting residual limb healing, such as the use of rigid versus soft immediate post-operative dressings,14,15 further highlight inconsistencies in clinical approaches. there is a need for objective measures, such as biomarkers, to evaluate wound healing and thus readiness for prosthetic fitting. biomarkers, as defined by the united states food and drug administration (u.s. fda) as measurable indicators of biological processes or responses to treatment,16 provide a means to minimize the subjectivity of current practices. however, their application in earlystage post-amputation healing remains largely unexplored.8,17,18 to address this research need, a scoping review was developed and implemented with the following aim: identify predictive, diagnostic, and/or indicative biomarkers (physical, chemical, or other) of healing of the tissues and structures found in the residual limbs of adults with amputation. to meet this aim, the following objectives were compiled: 1) collate and synthesize the reported definitions of healing and non-healing in the literature investigating healing of the tissues and structures found in the residual limbs of adults with amputation. 2) identify and collate physical biomarkers predictive, diagnostic, and/or indicative of healing repeated in sources investigating healing of the tissues and structures found in the residual limbs of adults with amputation. 3) identify and collate chemical biomarkers predictive, diagnostic, and/or indicative of healing repeated in sources investigating healing of the tissues and structures found in the residual limbs of adults with amputation. 4) assess the quality and levels of evidence from sources investigating the healing of the tissues and structures found in the residual limbs of adults with amputation. in the aim, biomarkers are classified by their nature and function. physical biomarkers are measurable attributes of the wound or tissue itself, such as wound ph or temperature, whilst chemical biomarkers are molecules found in biological tissue or fluids (e.g., sweat, sebum, saliva, and blood) that signal biological processes such as cytokines. functionally, predictive biomarkers assess the likelihood of a healing state or treatment response, while diagnostic biomarkers definitively confirm healing progression or status. indicative biomarkers suggest the presence of a condition or physiological state but are not definitive. 2: part 3 rationale, aims, and objectives this article (part 3) addresses objective 3 and is the final instalment in a three-part series examining objectives 1 through 3. part 1 highlighted significant gaps in defining healing and non-healing, emphasizing the need for an amputation-specific wound healing assessment scale incorporating objective measures like biomarkers.17 part 2 focused on physical biomarkers quantifying macrolevel physiological properties.18 while useful and easily noninvasively measured, these biomarkers, such as hemodynamic and oxygenation measures, often indicate changes resulting from cellular healing processes rather than directly representing the healing process itself. for example, wound temperature changes (a physical biomarker) may reflect inflammation, immune responses, vasodilation, and tissue metabolism.19-21 in contrast, chemical biomarkers like interleukins and c-reactive protein directly signal inflammatory responses22 and serve as more precise diagnostic indicators of healing mechanisms. currently, poor healing is defined by clinical endpoints like wound dehiscence or necrotic tissue formation.17 chemical biomarkers provide earlier insights into the healing process, allowing evaluation of treatments and rehabilitation programs. for instance, serum levels of matrix metalloproteinase 2 (mmp-2) and mmp-7 can predict wound dehiscence,23,24 as these mmps support extracellular matrix remodeling, which is essential for tensile skin strength.25 chemical biomarkers provide diagnostic insights into healing because they are intrinsic components of the healing process, with their levels directly reflecting specific healing mechanisms. for instance, the ki-67 protein functions as a marker of cellular proliferation in human cells.26,27 the proliferation of fibroblasts, endothelial cells, and keratinocytes is vital for cutaneous wound healing, as it constitutes the third stage of the four-step healing process.28 to demonstrate the indicative and diagnostic power of ki-67 in healing, escuin-ordinas et al.29 observed that diabetic wounds with higher wound closure scores exhibited significantly greater numbers of ki-67-positive https://doi.org/10.33137/cpoj.v8i1.43717 https://jps.library.utoronto.ca/index.php/cpoj/article/view/43715/33312 https://jps.library.utoronto.ca/index.php/cpoj/article/view/43716/33400 3 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 cells. similarly, collagen, another chemical biomarker, is embedded in essential healing mechanisms. it aids healing by attracting fibroblasts and promoting new collagen formation within the wound bed.30 thus, chemical biomarkers offer sensitive, specific measures of healing, improving understanding of post-amputation recovery and guiding rehabilitation. therefore, the aim of this review was to: identify predictive, diagnostic, and/or indicative chemical biomarkers of healing in the tissues and structures found in the residual limbs of adults with amputations. to achieve this aim, the following objectives were established: 1) identify and compile chemical biomarkers that are predictive, diagnostic, and/or indicative of healing as reported in sources investigating the tissues and structures of residual limbs in adults with amputations. 2) identify and summarize the techniques used to quantify these chemical biomarkers in studies focused on the healing of tissues and structures in residual limbs of adults with amputations. 3) assess the quality and levels of evidence in sources investigating the healing of tissues and structures found in the residual limbs of adults with amputations. methodology the detailed methodology and rationale for this review have been outlined previously in parts 117 and 2.18 briefly, the review adhered to the preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews (prisma-scr) checklist31,32 and the joanna briggs institute (jbi) guidelines.33-36 data were managed using excel version 2303 (microsoft, washington, usa) on windows 11 version 22h2 (microsoft, washington, usa). 1: inclusion criteria and search strategy finalized search terms, based on the terms “biomarker”, “amputation”, and “wound healing”, were applied to web of science, medline (ovid), embase (ovid), scopus, cochrane, pubmed, and cinahl databases. in stage one of screening titles and abstracts were screened using primary inclusion criteria: references to biomarkers of healing and publications from 2017 onward. given the limited exploration of chemical biomarkers in early-stage post-amputation healing,8,17,18 the inclusion criteria were broadened to cover tissues and structures biologically comparable to those in a residuum (e.g., skin, muscles, tendons, ligaments, bone, peripheral nervous system, and vasculature). in the second screening phase of full-texts, additional criteria were introduced, including reproducible methodologies, clear ethical approval (where applicable), and participants aged 18 years or older for human studies. bench research using in vitro, in silico, or murine models was considered for inclusion to capture biomarkers requiring cell or tissue samples which are ethically easier to obtain in these contexts. murine models were considered suitable due to sufficient genetic similarities to humans and common use in biological research.37 studies from all contexts and regions were considered if available in english. search results were managed in endnote 20 (version 20.2.1, clarivate, 2021), where duplicates were removed. 2: data extraction, analysis and presentation using a pre-defined data extraction tool (part 1, appendix a17), data (including chemical biomarkers and study characteristics) was extracted from sources that passed both screening rounds. study quality and evidence levels were evaluated using the qualsyst tool38 and jbi levels of evidence39 respectively. all extracted data are openly accessible in the review’s dataset.40 included sources were categorized by study (randomized controlled trial, case-controlled, observational, or bench research), wound (diabetic, amputation, or other), and model (human, murine, or other) type. chemical biomarkers that were observed more than once within and across study categories are reported on. these repeated chemical biomarkers are represented in tabular form and analyzed in comparison with existing literature for their indicative, predictive, and/or diagnostic potential in healing assessment. the review emphasizes recurring biomarkers, assuming their repeated observation indicates a stronger evidence base for the biomarker’s use, thus supporting future research. descriptive results section (section 3: measurement techniques of the repeated chemical biomarkers) and discussion section (section 2.2: quantification techniques) summarize biomarker quantification methodologies, offering additional context for the future use of the biomarkers in residual limb healing management. results 1: overall results 1.1: search strategy results as disseminated in part 1,17 the search strategy identified 7,041 sources for screening. of these, 3,735 were duplicates and were subsequently removed (part 1 prisma diagram). from the remaining 3,306 articles screened at the title and abstract level, 646 met the criteria for full-text screening. 219 articles satisfied the inclusion criteria and were selected for data extraction. primary reasons for exclusion included unclear methodologies, lack of ethical approval, and review article study type. of the 219 included sources, 203 reported on chemical biomarkers and are therefore the focus of this part 3 review. https://doi.org/10.33137/cpoj.v8i1.43717 https://jps.library.utoronto.ca/index.php/cpoj/article/view/43715/33312 https://jps.library.utoronto.ca/index.php/cpoj/article/view/43715/33312 https://jps.library.utoronto.ca/index.php/cpoj/article/view/43715/33312 4 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 1.2: quality and levels of evidence the quality assessment of the included sources revealed a strong emphasis on high-quality quantitative research. the majority of included sources (155 out of 203, or 76%)29,41-194 were classified as being of strong quality. an additional 40 sources195-234 were rated as good quality, while only 8 sources235-242 fell into the adequate quality category. none of the sources were categorized as having limited quality. contrastingly levels of evidence of the included sources demonstrated greater variability. in the prognosis category, 29 studies were classified as level 1.b, representing the second-highest evidence level, while only 3 studies64,68,173 fell into level 5.c, the lowest evidence tier (table 1). conversely, within the effectiveness category, a minimal number of studies were rated at the higher evidence levels, with 1 study207 classified as 1.b and 12 studies75,109,170,176,182,199,204,205,210,221,222,241 as 1.c (table 1). however, the majority of studies in this category, (96 studies) were assigned to level 5.c. this prevalence of level 5.c can be attributed to the significant number of bench research studies (study categories 9 to 13 in table 2), which are considered the lowest evidence level. for a comprehensive discussion of the quality and evidence levels of all 219 sources that satisfied the inclusion criteria for the overall review aim, refer to part 1.17 1.3 study types and characteristics of the 203 included sources, observational and bench research studies accounted for the largest proportions, compromising 89 and 97 sources, respectively (table 2). in contrast, only 13 sources were randomized controlled trials (rcts), and 6 were case-controlled studies. in categories 1 to 8 (table 3), studies involving human participants featured sample sizes ranging from just 1 participant in a case-controlled study145 to 11,943,000 participants in an observational retrospective study.140 this large sample size is attributed to the examination of annual rates of hemoglobin a1c (hba1c) testing and major leg amputations among medicare patients with diabetes spanning from 2003 to 2012 across 306 hospital referral regions in the usa.140 of the 106 sources, 95 provided gender information, with median male representation within each category ranging from 50% to 71% of participants (table 3). median mean participant ages exceeded 58 years across all study categories, with reported means ranging from 28.8204 to 77.3220 years. among the human participant studies, 68 investigated diabetic wounds, 27 focused on amputations (some resulting from diabetic wounds), and 20 explored other wound types (table 3). examples of the latter included skin wounds,50,175 lower limb mangled extremities,154 and infected wounds.128 similarly, to the human participant studies, bench research predominantly used male subjects and focused on diabetic wounds. of the murine models employed in 81% (79 sources) of the bench research studies, 56 sources utilized all male rats/mice, 6 sources used all female, and the remaining 17 sources used both or did not specify gender (table 2). in place of murine models, the remaining bench research studies utilized cell lines and tissue samples (15 sources41,42,45,53,95,98,108,132,135,139,151,166,196,237,242), a mathematical model (1 source76), and a gene expression dataset (1 source156). categories 9 to 11 (80 sources; table 2) specifically investigated diabetic wounds, while 7,55,101,141,148,184,211,214 4,64,161,163,173 2,87,155 and 4,53,139,166,242 sources explored skin wounds, traumatic injuries, sciatic nerve injuries, and wound/scratch assays (a type of cellbased wound model), respectively. 2: repeated chemical biomarkers of 38 identified repeated chemical biomarkers (table 4), interleukins (ils) were the most frequently reported, appearing in 50 sources (25% of 203 included sources). this was followed by glycated hemoglobin (hba1c) and vascular endothelial growth factor (vegf), which were utilized in 48 and 39 sources, respectively. other notable biomarkers included c-reactive protein (crp) and tumor necrosis factor (tnf), each reported in 34 studies, and albumin, which was employed in 31 sources. biomarkers such as matrix metalloproteinases (mmps), collagen, and creatinine were observed in 10% to 14% of sources, whereas less frequently reported biomarkers, including zinc and myeloperoxidase (mpo), were present in only 2% to 5% of studies. the distribution of repeated biomarkers across study categories (table 2 and table 4) underscores the relationship between study design and biomarker prevalence. for instance, 27 of the 38 biomarkers were identified in bench research studies (study categories 9 to 13) which primarily use murine models (79 of 97 bench research included sources), indicating that such study types provide more detailed chemical biomarker data. in contrast, biomarkers exclusively observed in human participant studies only (study categories 1 to 8) include hba1c, crp, white blood cells (wbc), hemoglobin (hb), cholesterol, erythrocyte sedimentation rate (esr), fasting blood sugar, neutrophils and lymphocytes, platelets, zinc, and hemoglobin, all of which are typically routine blood biomarkers used to assess participants’ general health status. additionally, the high prevalence of diabetic wound studies (explored in study categories 1 to 3, 6, and 9 to 11) is reflected in the extensive use of hba1c, which is clinically utilized for diabetes diagnosis.243 https://doi.org/10.33137/cpoj.v8i1.43717 https://jps.library.utoronto.ca/index.php/cpoj/article/view/43715/33312 5 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 table 1: levels of evidence of the 203 included articles ranked using the jbi (joanna briggs institute) levels of evidence (44) (na = not applicable). evidence level jbi evidence level study categories effectiveness diagnosis prognosis 1.a 0 0 0 1.b 1 (207) 7 (67, 73, 85, 130, 154, 217, 239) 29 (47, 61, 69, 72-74, 85, 86, 90, 115, 116, 120, 123, 130, 138, 144, 149, 154, 157, 159, 162, 169, 175, 197, 217, 225, 234, 239, 240) 1.c 12 (75, 109, 170, 176, 182, 199, 204, 205, 210, 221, 222, 241) na na 1.d 0 na na 2.a 0 0 0 2.b 0 0 0 2.c 0 na na 2.d 0 na na 3.a 0 0 0 3.b 1 (104) 0 42 (43, 44, 46, 58, 60, 62, 63, 65, 67, 77-79, 81-84, 92, 94, 100, 102, 106, 128, 129, 131, 133, 134, 140, 142, 147, 150, 160, 168, 171, 172, 179, 181, 185, 200, 220, 228, 230, 235) 3.c 3 (89, 203, 217) na na 3.d 3 (97, 127, 195) na na 3.e 30 (43, 46, 48, 50, 52, 57, 59, 62, 67, 73, 74, 85, 90, 94, 99, 129, 131, 143, 144, 146, 149, 164, 175, 185, 189, 198, 224, 236, 238, 240) na na 4.a 0 0 0 4.b 0 0 2 (97, 152) 4.c 0 na na 4.d 1 (145) na na 5.a 0 0 0 5.b 0 0 0 5.c 96 (29, 41, 42, 45, 49, 51, 53-56, 64, 66, 68, 70, 71, 76, 80, 87, 88, 91, 93, 95, 96, 98, 101, 103, 105, 107, 108, 110-114, 117119, 121, 122, 124-126, 132, 135-137, 139, 141, 148, 151, 153, 155, 156, 158, 161, 163, 165-167, 174, 177, 178, 180, 183, 184, 186-188, 190-194, 196, 201, 202, 206, 208, 209, 211-216, 218, 219, 223, 226, 227, 229, 231-233, 237, 242) 3 (68, 126, 194) 3 (64, 68, 173) table 2: summary of the study types of all 203 included sources utilizing chemical biomarkers. the sources are categorized by study type, wound type, and model type, with reference numbers provided for each category as used throughout the review. study type category reference number number (%) of included sources included source references randomized controlled trial 1 13 (6%) (75, 109, 170, 176, 182, 199, 204, 205, 207, 210, 221, 222, 241) case-controlled study 2 6 (3%) (97, 127, 131, 145, 152, 195) observational prospective diabetic wounds 3 29 (14%) (47, 48, 59, 61, 62, 69, 72-74, 89, 90, 115, 120, 123, 138, 143, 144, 146, 157, 197, 198, 203, 217, 224, 225, 234, 236, 238, 239) amputation 4 8 (4%) (57, 85, 130, 149, 159, 162, 169, 240) other wounds 5 6 (3%) (50, 52, 86, 99, 154, 175) retrospective diabetic wounds 6 18 (9%) (58, 63, 67, 81, 84, 92, 94, 100, 133, 134, 164, 171, 172, 179, 181, 185, 230, 235) amputation 7 14 (7%) (43, 44, 46, 60, 79, 83, 129, 140, 142, 150, 160, 189, 200, 220) other wounds 8 12 (6%) (65, 77, 78, 82, 102, 104, 106, 116, 128, 147, 168, 228) bench research diabetic wounds rat models 9 25 (12%) (51, 54, 70, 88, 96, 110, 111, 113, 117, 121, 122, 125, 136, 137, 165, 167, 174, 186, 191, 218, 223, 229, 231-233) mouse models 10 41 (20%) (29, 49, 56, 66, 71, 80, 91, 93, 103, 105, 107, 112, 114, 118, 119, 124, 126, 153, 158, 177, 178, 180, 183, 187, 188, 190, 192-194, 201, 202, 206, 208, 209, 212, 213, 215, 216, 219, 226, 227) other models 11 14 (7%) (41, 42, 45, 68, 76, 95, 98, 108, 132, 135, 151, 156, 196, 237) other wounds rat/mouse models 12 13 (6%) (55, 64, 87, 101, 141, 148, 155, 161, 163, 173, 184, 211, 214) other models 13 4 (2%) (53, 139, 166, 242) https://doi.org/10.33137/cpoj.v8i1.43717 6 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 table 3: the characteristics (wound type, sample size, gender distribution, and age) of the included sources involving human participants (study categories 1 to 8; table 2). note that for wound type some sources fall under more than one wound type. for example, norvell et al.142 (a category 7 source) investigated wound healing of lower limb amputation due to diabetes or peripheral arterial disease. the notation “no. (%) of references” indicates the number and percentage of sources that provide characteristic information relative to the total number of sources within that category (t.g. = treatment groups; c.g. = control groups; no. = number; na = not applicable). study category 1 2 3 4 5 6 7 8 wound type totals diabetic 10 (75, 170, 176, 182, 199, 205, 207, 221, 222, 241) 5 (127, 131, 145, 152, 195) 29* 1 (159) 0 18* 5 (83, 129, 140, 142, 200) 0 amputation 1 (109) 4 (97, 131, 145, 152) 0 8* 0 0 14* 0 other 2 (204, 210) 0 0 0 6* 0 0 12* sample size totals range (min-max) 15-200 1-120 4-684 10-556 5-735 48-1032 46-11943000 45-637 median 33 20 57 21 18 148 205 125 no. (%) of references 13 (100%) 6 (100%) 29 (100%) 8 (100%) 6 (100%) 18 (100%) 14 (100%) 12 (100%) sample gender (% male) totals range (min-max) 40%-82% 0%-100% 33%-91% 55%-100% 20%-79% 44%-85% 45%-99% 54%-82% median 63% 50% 63% 64% 62% 64% 71% 67% no. (%) of references 11 (85%) (109, 170, 176, 182, 199, 204, 205, 207, 210, 222, 241) 6 (100%) 26 (90%) (47, 48, 59, 61, 62, 72-74, 89, 90, 115, 120, 123, 138, 143, 144, 146, 157, 197, 198, 203, 217, 224, 225, 234, 239) 8 (100%) 4 (67%) (52, 86, 99, 175) 15 (83%) (58, 63, 67, 81, 84, 92, 94, 100, 164, 171, 172, 181, 185, 230, 235) 14 (100%) 11 (92%) (65, 77, 78, 82, 102, 104, 106, 116, 128, 147, 168) sample mean age (years) total range (min-max) t.g.: 40.669.0; c.g.: 28.8-64.7 60.2-65.0 47.4-73.4 49.0-74.0 na 54.5-72.5 38.0-77.3 56.0-74.0 median t.g. 58.1; c.g.: 58.9 61.5 59.5 65.2 na 61.2 66.7 72.0 no. (%) of references 12 (92%) (75, 109, 170, 176, 182, 199, 204, 205, 207, 210, 222, 241) 3 (50%) (97, 127, 145) 27 (93%) (47, 48, 59, 61, 62, 69, 72-74, 89, 90, 115, 120, 123, 138, 143, 144, 146, 157, 197, 198, 203, 217, 224, 225, 234, 239) 6 (75%) (85, 149, 159, 162, 169, 240) na 16 (89%) (58, 63, 67, 81, 84, 92, 94, 100, 133, 134, 164, 171, 181, 185, 230, 235) 12 (86%) (43, 46, 60, 83, 129, 140, 142, 150, 160, 189, 200, 220) 8 (67%) (65, 77, 78, 102, 104, 106, 147, 168) sample age range (years) total range (min-max) na 35-94 20-89 23-87 28-88 23-100 26-96 22-96 no. (%) of references na 3 (50%) (131, 152, 195) 11 (38%) (48, 61, 69, 90, 115, 138, 143, 198, 203, 217, 225) 3 (38%) (57, 85, 159) 4 (67%) (52, 86, 99, 175) 6 (33%) (63, 84, 94, 133, 134, 235) 2 (14%) (43, 129) 1 (8%) (147) sample median age (years) totals range (min-max) na na na na na na 47.0-62.0 31.0-71.2 median na na na na na 72.5 54.5 68.4 no. (%) of references na na na na na 1 (6%) (172) 2 (14%) (44, 79) 3 (25%) (82, 116, 128) *references are provided in table 2. https://doi.org/10.33137/cpoj.v8i1.43717 7 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 table 4: a comprehensive breakdown of the repeated chemical biomarkers. a biomarker was considered “repeated” if it was used in more than one source within a study category and appeared in more than one study category. the occurrence of these biomarkers in the 203 included sources is presented, along with their representation across the various study categories (table 2; freq. = frequency; ils = interleukins; hba1c = glycated hemoglobin; vegf = vascular endothelial growth factor; crp = c-reactive protein; tnf = tumor necrosis factor; tgf = transforming growth factor; wbc = white blood cells; cd = cluster of differentiation; hb = hemoglobin; α-sma = alpha-smooth muscle actin; mmps = matrix metalloproteinases; fgf = fibroblast growth factor; esr = erythrocyte sedimentation rate; pdgf = platelet-derived growth factor; ccls = chemokine (c-c motif) ligands; mcps = monocyte chemoattractant proteins; egf = endothelial growth factor; ifn = interferon; inos = inducible nitric oxide synthase; enos = endothelial nitric oxide synthase; hif-1α = hypoxia-inducible factor 1 alpha; ki-67 = kiel 67; nf-κb = nuclear factor kappa b; mpo = myeloperoxidase; timps = tissue inhibitors of metalloproteinases; ros = reactive oxygen species; p-erk = phosphorylated extracellular signal-regulated kinase; igf = insulin-like growth factor). repeated chemical biomarkers sources study categories freq. % included sources references freq. % of categories categories included ils 50 25% (42, 45, 48, 54, 57, 75, 80, 87, 91, 101, 103, 105, 107, 108, 110, 111, 117, 121, 124, 130, 135, 137, 138, 153, 156, 158, 161, 167, 170, 173, 176, 177, 180, 183, 187, 191, 194, 196, 198, 205, 206, 209, 212, 213, 215, 216, 223, 226, 227, 236) 7 54% 1, 3, 4, 9, 10, 11, 12 hba1c 48 24% (46, 58, 59, 61, 63, 67, 69, 72-74, 81, 83, 84, 90, 92, 94, 102, 109, 123, 133, 134, 140, 143-147, 152, 157, 159, 160, 162, 169, 170, 172, 181, 189, 195, 197, 198, 200, 203, 207, 222, 224, 228, 230, 234) 7 54% 1, 2, 3, 4, 6, 7, 8 vegf 39 19% (42, 48, 51, 52, 54, 56, 59, 70, 75, 76, 99, 103, 108, 112-115, 119, 121, 124, 125, 143, 148, 153, 158, 161, 165, 167, 177, 184, 186, 190, 191, 193, 204, 205, 209, 223, 236) 7 54% 1, 3, 5, 9, 10, 11, 12 crp 34 17% (46, 47, 65, 69, 74, 78, 82-84, 90, 92, 94, 102, 106, 123, 129, 133, 134, 145, 150, 152, 157, 160, 164, 168, 170, 172, 185, 198, 199, 209, 220, 230, 235) 6 46% 1, 2, 6, 7, 8 tnf 34 17% (42, 45, 54, 59, 71, 75, 76, 101, 103, 117, 121, 124, 135, 137, 153, 156, 158, 161, 167, 170, 173, 180, 191, 196, 198, 209, 212, 215, 216, 222, 223, 227, 232, 236) 6 46% 1, 3, 9, 10, 11, 12 albumin 31 15% (43, 44, 46, 58, 60, 63, 65, 77-79, 83, 84, 90, 102, 104, 106, 116, 133, 134, 157, 160, 161, 163, 172, 173, 179, 189, 198, 220, 234, 235) 5 38% 3, 6, 7, 8, 12 tgf 29 14% (42, 51, 59, 70, 75, 76, 103, 113, 117, 121, 124, 132, 135, 137, 148, 158, 161, 165, 167, 170, 182, 183, 190, 191, 213, 215, 233, 236, 238) 6 46% 1, 3, 9, 10, 11, 12 wbc 27 13% (44, 47, 59, 63, 77, 78, 82-84, 90, 94, 116, 123, 133, 134, 142, 152, 157, 159, 169, 172, 195, 220, 224, 230, 234, 235) 6 46% 2, 3, 4, 6, 7, 8 cd31 27 13% (51, 55, 66, 71, 80, 93, 96, 103, 105, 107, 114, 119, 148, 165, 174, 177, 187, 190, 191, 194, 206, 208, 209, 211, 218, 219, 233) 3 23% 9, 10, 12 hb 26 13% (46, 47, 58, 61, 63, 69, 72, 78, 83, 84, 90, 94, 106, 116, 120, 133, 134, 145, 160, 168, 172, 189, 195, 197, 198, 217) 5 38% 2, 3, 6, 7, 8 α-sma 23 11% (54, 55, 71, 87, 88, 103, 113, 117, 119, 136, 148, 153, 174, 177, 178, 180, 190-192, 213, 215, 216, 233) 3 23% 9, 10, 12 mmps 22 11% (41, 45, 54, 59, 101, 113, 115, 167, 177, 191, 193, 202, 203, 211, 215, 216, 223, 226, 227, 232, 236, 239) 5 38% 3, 9, 10, 11, 12 collagen 21 10% (41, 54, 55, 59, 71, 75, 88, 105, 108, 113, 117, 137, 153, 191, 212-214, 216, 233, 236, 241) 6 46% 1, 3, 9, 10, 11, 12 creatinine 20 10% (77, 78, 84, 94, 116, 133, 134, 144, 157, 159, 161-163, 170, 173, 198, 199, 228, 234, 235) 6 46% 1, 3, 4, 6, 8, 12 cholesterol 16 8% (67, 69, 72, 74, 81, 84, 90, 92, 109, 133, 134, 170, 172, 224, 230, 234) 3 23% 1, 3, 6 fgf 16 8% (41, 42, 49, 51, 98, 105, 107, 125, 136, 139, 148, 156, 166, 184, 191, 215) 5 38% 9, 10, 11, 12, 13 esr 14 7% (47, 59, 84, 94, 123, 133, 134, 157, 164, 198, 199, 207, 230, 235) 3 23% 1, 3, 6 ccls/mcps 12 6% (42, 45, 108, 135, 148, 161, 177, 196, 206, 209, 212, 215) 3 23% 10, 11, 12 pdgf 11 5% (42, 56, 76, 124, 125, 137, 141, 143, 161, 186, 236) 5 38% 3, 9, 10, 11, 12 fasting blood sugar 11 5% (61, 63, 67, 74, 84, 100, 133, 134, 143, 171, 230) 2 15% 3, 6 neutrophils and lymphocytes 11 5% (47, 61, 63, 90, 129, 157, 171, 172, 179, 200, 224) 3 23% 3, 6, 7 egf 10 5% (41, 42, 56, 139, 143, 151, 166, 193, 198, 238) 4 31% 3, 10, 11, 13 total proteins 10 5% (54, 92, 94, 117, 133, 134, 137, 185, 198, 234) 3 23% 3, 6, 9 platelets 9 4% (44, 47, 69, 79, 84, 133, 134, 142, 200) 3 23% 3, 6, 7 ifn 9 4% (41, 45, 48, 91, 161, 173, 183, 198, 227) 4 31% 3, 10, 11, 12 inos and enos 9 4% (71, 124, 167, 180, 191, 194, 206, 209, 226) 2 15% 9, 10 hif-1α 7 3% (48, 114, 119, 186, 191, 194, 236) 3 23% 3, 9, 10 bacteria 7 3% (61, 91, 115, 138, 201, 225, 227) 2 15% 3, 10 ki-67 7 3% (29, 51, 165, 177, 191, 219, 231) 2 15% 9, 10 nf-κb 6 3% (48, 54, 117, 121, 167, 236) 2 15% 3, 9 mpo 6 3% (121, 213, 216, 219, 227, 233) 2 15% 9, 10 zinc 5 2% (58, 104, 106, 133, 134) 2 15% 6, 8 timps 5 2% (45, 108, 115, 203, 236) 2 15% 3, 11 cd68 5 2% (51, 117, 148, 155, 233) 2 15% 9, 12 ros 5 2% (49, 118, 165, 202, 218) 2 15% 9, 10 hematocrit 4 2% (44, 142, 152, 195) 2 15% 2, 7 erk, p-erk, and p-erk1/2 4 2% (29, 54, 113, 192) 2 15% 9, 10 igf 4 2% (48, 124, 177, 236) 2 15% 3, 10 https://doi.org/10.33137/cpoj.v8i1.43717 8 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 3: measurement techniques of the repeated chemical biomarkers gene expression was analyzed for 15 of the repeated chemical biomarkers using qrt-pcr (quantitative real-time polymerase chain reaction), including taqman assays (table 5 and table 6). immunostaining, to quantify biomarker expression in wound tissue samples, was similarly used for 15 of the 37 repeated biomarkers, such that qrt-pcr and immunostaining were the most frequently used quantification techniques. interestingly, quantifying wound tissue biomarker expression used the greatest array of measurement techniques, including elisa (enzyme-linked immunosorbent assay) kits, western blot, immunostaining, gelatine zymography, and multiplex immunoassays. the number of measurement techniques for each biomarker varied. mmps, for example, were assessed using 7 techniques, whereas markers found in the blood such as hba1c (glycated hemoglobin), hb (hemoglobin), wbc (white blood cells), and platelets were analyzed using only one method, a routine blood test. table 5: measurement techniques reported in included sources used to quantify gene expression, serum expression, and/or wound tissue expression of the identified repeated chemical biomarkers (elisa = enzyme-linked immunosorbent assay; qrt-pcr = quantitative real-time polymerase chain reaction; biomarker abbreviations are defined in the table 4 caption). biomarker measurement techniques gene expression serum expression wound tissue expression repeated chemical biomarkers q r t -p c r t a q m a n a s s a y s r o u ti n e b lo o d t e s t e l is a k it m u lt ip le x im m u n o a s s a y e l is a k it w e s te rn b lo t im m u n o s ta in in g g e la ti n z y m o g ra p h y m u lt ip le x im m u n o a s s a y l u m in o lb a s e d b io lu m in e s c e n c e im a g in g albumin ✓ α-sma ✓ ccls/mcps ✓ ✓ ✓ ✓ ✓ cd31 ✓ cd68 ✓ cholesterol ✓ collagen ✓ creatinine ✓ crp ✓ egf ✓ ✓ ✓ erk, p-erk, and perk1/2 ✓ ✓ ✓ esr ✓ fasting blood sugar ✓ fgf ✓ ✓ ✓ hematocrit ✓ hb ✓ hba1c ✓ hif-1α ✓ ✓ ✓ ✓ ifn ✓ ✓ ✓ ✓ igf ✓ ils ✓ ✓ ✓ ✓ inos and enos ✓ ✓ ki-67 ✓ mmps ✓ ✓ ✓ ✓ ✓ ✓ ✓ mpo ✓ ✓ neutrophils and lymphocytes ✓ nf-κb ✓ ✓ ✓ pdgf ✓ ✓ ✓ platelets ✓ ros ✓ ✓ tgf ✓ ✓ ✓ timps ✓ ✓ ✓ ✓ tnf ✓ ✓ ✓ total proteins ✓ vegf ✓ ✓ ✓ ✓ ✓ wbc ✓ zinc ✓ totals 15 3 14 8 1 12 9 16 1 1 1 % of 37 biomarkers 41% 8% 3% 22% 3% 32% 24% 43% 3% 3% 3% https://doi.org/10.33137/cpoj.v8i1.43717 9 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 table 6: overview of the measurement techniques utilized in the included sources to quantify the chemical biomarkers referenced (table 4 (biomarkers); table 5 (corresponding quantification techniques); elisa = enzyme-linked immunosorbent assay; mmp = matrix metalloproteinase; qrt-pcr = quantitative real-time polymerase chain reaction; taqdna = taq deoxyribonucleic acid polymerase; mirna = micro ribonucleic acid; bli = bioluminescence imaging; nadph = nicotinamide adenine dinucleotide phosphate; ros = reactive oxygens species). chemical biomarker measurement technique brief description of principle gelatin zymography method to detect proteolytic enzymes capable of degrading gelatin from biological sources such as the gelatinases mmp-2 and mmp-9 (244). elisa employs the catalytic properties of enzymes to detect and quantify immunologic reactions (245). it is a solid-phase test generating a color reaction and is therefore easy to interpret (246). multiplex immunoassay it utilizes traditional immunoassay methods working on the principle of exploiting binder molecules (antibodies, proteins, or peptides) to capture circulating proteins or antibodies (246). unlike elisa, multiplex immunoassays enable the simultaneous measurement of multiple analytes in a single biological sample (246). taqman assay this is a specific form of qrt-pcr and one of the earliest methods introduced for real-time pcr monitoring (247). it exploits the 5' endonuclease activity of taqdna polymerase (an enzyme) to cleave an oligonucleotide probe during pcr, thereby generating a detectable signal (247). western blot method to detect protein molecules among a mixture (248). the key steps include cell lysis (makes protein unfold into linear chains coated with a negative charge), gel electrophoresis (sorts proteins by size), blocking (prevents nonspecific reactions from occurring), incubating the sample with a primary antibody (binds specifically to the protein of interest), and finally incubating with a secondary antibody which binds to the primary and produces some signal (such as color or light) (248). qrt-pcr this is considered the gold standard for quantifying mirnas with high sensitivity and specificity (249). it utilizes fluorescence generated during pcr to reflect the amount of dna amplicons in a sample at a specific time (250). immunostaining requires incubating a tissue sample with antibodies specific to the protein of interest, which can then be visualized with a fluorescence (immunofluorescence) or chromogen (immunohistochemistry) which is bound to or binds to the antibody (251). luminol-based bioluminescence imaging (bli) as demonstrated by nguyen et al. (202), superoxide derived from nadph oxidase can be detected through bioluminescence imaging by intraperitoneally injecting an animal with l-012. l-012 is a luminol-based chemiluminescent probe that emits light upon reacting with ros (252). the intensity of the luminescent signal, measured in photons per second per centimeter squared, correlates with the amount of superoxide present, where a higher signal indicates greater superoxide levels, the most abundant ros (253). table 7: classification of the repeated chemical biomarkers used in included sources as predictive, indicative, or diagnostic when considering their influence on the healing process and their behavior in the reviewed sources. biomarker predictive indicative diagnostic routine blood profile biomarkers cholesterol (includes high and low-density lipoproteins and triglycerides) ✓ erythrocyte sedimentation rate (esr) ✓ ✓ fasting blood sugar (or fasting plasma glucose) ✓ glycated hemoglobin (hba1c) ✓ hematocrit (hct) ✓ ✓ hemoglobin (hb) ✓ neutrophils and lymphocytes ✓ platelets ✓ total proteins ✓ ✓ white blood cell (wbc) counts ✓ growth factors epidermal growth factor (egf) ✓ fibroblast growth factor (fgf) ✓ insulin-like growth factor (igf) ✓ platelet-derived growth factor (pdgf) ✓ transforming growth factor (tgf) ✓ tumor necrosis factor (tnf) ✓ vascular endothelial growth factor (vegf) ✓ albumin ✓ alpha-smooth muscle actin (α-sma) ✓ ✓ bacteria (includes colony-forming units, bacterial counts, and bacterial rna assessment) ✓ cc chemokines (also known as monocyte chemoattractant [mcps]) ✓ clusters of differentiation (cd68 and cd31) ✓ collagen ✓ ✓ c-reactive protein (crp) ✓ ✓ creatinine ✓ endothelial and inducible nitric oxide synthase (enos and inos) ✓ extracellular signal-regulated kinases (erks) ✓ ✓ hypoxia inducible factor-1 (hif-1) ✓ interferon (ifn) ✓ ✓ interleukins (ils) ✓ ✓ ✓ kiel-67 (ki-67) ✓ matrix metalloproteinases (mmps) and tissue inhibitors of metalloproteinases (timps) ✓ ✓ myeloperoxidase (mpo) ✓ nuclear factor kappa-light-chain-enhancer of activated b cells (nf-κb) ✓ reactive oxygen species (ros) ✓ zinc ✓ https://doi.org/10.33137/cpoj.v8i1.43717 10 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 bacteria were assessed somewhat differently, as presented in the following list, and are therefore excluded from table 5: • biofilms were detected using the tissue culture plate method. • antimicrobial susceptibility testing was performed using the kirby-bauer disc diffusion method. • molecular characterization of biofilm-forming resistant isolates was done by pcr. discussion 1: key findings this scoping review identifies chemical biomarkers associated with the healing of tissues and structures in the residual limbs of adults with amputation. these biomarkers serve predictive, indicative, and diagnostic purposes, offering a foundation for improved prosthesis readiness and residuum health assessments. predictive biomarkers such as bacterial counts, nutritional markers (e.g., zinc, albumin), and routine blood markers (e.g., glycated hemoglobin [hba1c], white blood cells [wbc], c-reactive protein [crp]) indicate health status and help anticipate healing outcomes. for instance, elevated hba1c is predictive of impaired healing due to hyperglycemia. indicative biomarkers like growth factors, ils, and reactive oxygen species (ros) reflect critical healing processes, enabling monitoring of healing progression. diagnostic biomarkers, such as alpha-smooth muscle actin (α-sma), offer clear insights into wound healing at the cellular level. despite identifying 38 biomarkers in research, only routine blood markers are used clinically. limited application stems from reliance on experimental methods (e.g., immunohistochemical staining) often restricted to animal studies. bridging this gap requires advancements in measurement techniques that negate the need for wound tissue samples. population-specific factors (e.g., age, gender, comorbidities) and measurement differences (e.g., timing, location) influence healing and biomarker behavior. thus, to improve healing assessment objectivity, a combination of biomarkers is required. 2: repeated chemical biomarkers 2.1: chemical biomarkers to classify a biomarker as predictive, indicative, or diagnostic (table 7), its role in the healing process and observed behavior in the reviewed sources must be considered. for example, interleukins (ils), a class of cytokines predominantly expressed by leukocytes, are integral to inflammatory and immune responses254 and critical for wound healing. for instance, il-2 receptors are present on macrophages, lymphocytes, keratinocytes, fibroblasts, vascular endothelial cells, and t-cells; cells that influence the entire healing process.255 additionally, research on the treatment of diabetic foot ulcers (dfus) with therapeutic magnetic resonance (tmr®) devices revealed increased il-10 expression and improved healing.75 similarly, elevated il-1rl2 and il-33 gene expression is linked to inflammation and bone remodeling, suggesting predictive potential for healing post-percutaneous osseointegrated prosthesis implantation.130 thus, ils can be predictive, indicative, and diagnostic of healing. predictive biomarkers, such as bacterial counts, nutritional markers (like zinc and albumin), and routine blood profile markers like glycated hemoglobin (hba1c), white blood cell counts (wbcs), and c-reactive protein (crp), indicate an individual’s health status, enabling the anticipation of healing outcomes. for example, bacterial counts reflect the wound microbiome and potential infection, which impairs healing.256 similarly, hba1c indicates glycemic control243 and predicts healing, as hyperglycemia inhibits keratinocyte migration and promotes oxidative stress through reactive oxygen species (ros) production.257 zinc is a marker of nutritional status,258 with deficiency negatively impacting healing,259 and supplementation accelerating it.260 predictive biomarkers primarily identify comorbidities or conditions, such as infection or poor nutritional status, that contribute to impaired healing rather than diagnosing specific healing mechanisms. this makes them appropriate for pre-amputation risk assessments, given the high prevalence of comorbidities, such as diabetes, among individuals undergoing amputation. for example, the scottish physiotherapy amputee research group (sparg) reported in 2019 that 56% of lower limb amputees recorded had the etiology of diabetes.261 indicative biomarkers, including growth factors (table 7), ils, and signaling molecules like ros and nuclear factor kappa-light-chain-enhancer of activated b cells (nf-κb), reflect biological processes essential for healing (e.g., tissue remodeling and cellular proliferation), enabling monitoring and quantification of progress. for example, vascular endothelial growth factor (vegf) promotes angiogenesis by influencing vascular endothelial cells, keratinocytes, and macrophages.262 supporting this, kim et al.103 demonstrated that increased vegf levels correlated with near-complete epithelial coverage in a diabetic wound mouse model treated with substance p, indicating healing. the 6 identified diagnostic biomarkers (table 7) provide insights into tissue structure and composition, enabling precise healing assessments. for example, alpha-smooth muscle actin (α-sma), expressed temporarily by myofibroblasts during their differentiation from granulation tissue fibroblasts,263 serves as a marker of smooth muscle https://doi.org/10.33137/cpoj.v8i1.43717 11 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 differentiation and wound contraction,264 diagnosing healing progression during the epithelialization phase. by directly reflecting healing at a cellular level, diagnostic biomarkers offer the most objective insights into healing progression and hold high objective value for inclusion in a postamputation healing assessment scale. while numerous biomarkers show promise for enhancing post-amputation healing, their clinical application requires careful categorization and validation. indicative biomarkers, such as growth factors, also diagnose specific molecular mechanisms, suggesting potential as diagnostic tools. for example, ki-67, a marker of cellular proliferation,26,27 plays a diagnostic role by identifying fibroblast, endothelial cell, and keratinocyte proliferation (key processes in cutaneous wound healing).28 however, further research in amputeespecific populations is needed to validate such biomarkers for clinical use, facilitating their transition from bench research to diagnostic applications. many identified biomarkers, including ils and wbcs, are integral to immune and inflammatory responses. elevated wbc counts (leukocytosis), for instance, are linked to higher risks of re-amputation, longer post-amputation healing times, and greater chance of amputation due to dfus.44,84,235 however, leukocytosis may stem from factors unrelated to wound healing, such as infections elsewhere, medications, stress, or serious conditions like leukemia.265 to address this variability in biomarker causation, a broader array of biomarkers is needed to capture all phases of healing and account for patient-specific factors known to affect healing like stress,266 poor nutrition,259 renal disease,267 smoking,268,269 and alcohol use.270 the limitations of predictive biomarkers are evident in conflicting findings. to illustrate, adams et al.43 reported higher mortality rates after transmetatarsal amputation (tma) in patients with preoperative albumin levels below 3.5 g/dl (p < 0.05). similarly, brookes et al.58 observed significantly lower albumin levels in amputees compared to non-amputees (p = 0.03). however, ahn et al.44 found no significant correlation between serum albumin and tma reamputation rates (p = 0.644). although the sources differ in participant populations and follow-up durations, the contrasting conclusions highlight the need for a biomarker profile rather than relying on a single predictive biomarker. this will enhance predictive accuracy whilst acknowledging a biomarker’s limitations. future research must clarify the impact of quantification timing and location on biomarker levels during healing, to optimize their clinical application. for example, anguianohernandez et al.48 demonstrated that nf-κb expression and localization are indicative of healing progression. in dfu patients treated with hyperbaric oxygen therapy, nf-κb expression decreased, and its localization shifted from nuclear to cytoplasmic in endothelial cells and fibroblasts, correlating with complete healing.48 these findings stress the importance of not only measuring biomarker levels but also assessing their localization to fully understand their role in the healing process. a comprehensive biomarker profile that spans predictive, indicative, and diagnostic categories is essential to enhance the assessment and management of post-amputation healing. such profiles would account for comorbidities, capture all healing stages, and improve clinical decisionmaking, particularly in early prosthetic rehabilitation. 2.2: quantification techniques the method by which a biomarker is quantified dictates its applicability in research and clinical settings. diagnostic markers like ki-67, cds (clusters of differentiation), α-sma, and erks (extracellular signal-regulated kinases) rely on techniques such as immunohistochemical staining, immunofluorescence, or rt-qpcr (table 5), which require tissue samples, making them time-consuming, costly, and ethically challenging in human studies. consequently, their use is largely confined to murine models emphasizing the need for advancements in quantification techniques. for example, ros can be quantified via non-invasive in vivo chemiluminescence imaging,202 validated in animal models271 but untested clinically. conversely, biomarkers like crp and routine blood markers, measurable through peripheral blood draws,272 are more feasible for human studies and already employed in clinical settings.273 unfortunately, such biomarkers are typically predictive or indicative, whereas markers like ki-67 and α-sma are diagnostic and thus hold greater clinical value. developing accessible, cost-effective, and ethically viable quantification techniques will facilitate the integration of chemical biomarkers into research and clinical practice, ultimately optimizing post-amputation healing and prosthetic rehabilitation outcomes. 3: overall search results and study characteristics trends in study characteristics align with the findings from the part 2 review;18 for full details, refer to part 2. diabetic wounds dominated the reviewed sources, reflecting the global diabetes burden,274 with dfus being a major diabetic complication275 and a risk factor for amputation,276,277 reinforcing the importance of pre-amputation biomarker assessments to identify comorbidities predictive of nonhealing like diabetes.8 aging further complicates the healing process, with the median mean age of participants in study categories 1 to 8 ranging from 58.1 to 72.0 years. non-healing wounds are often linked to vascular disease,278 venous insufficiency,279 https://doi.org/10.33137/cpoj.v8i1.43717 https://jps.library.utoronto.ca/index.php/cpoj/article/view/43716/33400 12 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 areas of high unrelieved pressure,280 diabetes,281 and disability;282 conditions that are increasingly prevalent as the population ages.281 aging contributes to prolonged inflammation and increased ros production,283 necessitating objective measures to monitor wound healing, particularly for older adults requiring prosthetic fitting.261 gender differences were evident, with male participants at higher risk for dfu development,284 poorer dfu healing,285 increased post-surgery infection rates,286 and higher inhospital immortality rates after trauma.287 this highlights the need for gender-specific research288 and biomarkers unaffected by hormonal or gender-related factors. most included sources investigated wound healing in populations similar to individuals with amputation rather than residual limb healing specifically, highlighting the lack of standardized approaches and the need for a foundational database of biomarkers for residual limb recovery, particularly for lower limbs, which have unique health requirements due to weight-bearing during ambulation. 4: methodological discussion 4.1: methodological strengths this review’s methodology aligns with part 1 and part 2; detailed discussions of methodological strengths, limitations, and ethical considerations can be found there. this review broadly explored chemical biomarkers associated with post-amputation healing, serving as a foundation for future systematic reviews on specific biomarkers supported by high-quality evidence. a key strength is its focus on diagnostic, predictive, and indicative biomarkers with the potential to improve the prevention and treatment of non-healing surgical sites and to enhance postamputation healing assessment, enabling timely prosthetic interventions.289 4.2: methodological limitations limitations include the unreliability of animal studies due to biological differences290 and the oversimplification of human biology in mathematical models,291,293 requiring cautious interpretation of biomarker behavior reported in these source types. while the review included wound types relevant to the residuum, future research should differentiate between the healing of secondary intention wounds (e.g., dfus) and primary intention wounds (e.g., surgical sites). additionally, prioritizing only repeatedly studied biomarkers risks oversimplification. 5: ethical considerations ethical rigor was prioritized over strict adherence to evidence hierarchies, such that only studies with clear ethical approval and informed consent from participants aged 18 or older were included. grey literature was reviewed to reduce bias,294 but none met the inclusion criteria due to methodological shortcomings and lack of ethical transparency. conclusion this scoping review identified 38 repeated chemical biomarkers relevant to healing in the tissues and structures in residual limbs of adults with amputation, classified as predictive, indicative, or diagnostic based on their function and behavior in the 203 reviewed sources. predictive biomarkers, such as blood markers (e.g., glycated hemoglobin [hba1c], white blood cells [wbc]), assess health and healing potential, aiding pre-amputation risk assessments and identifying conditions impairing healing, like infection or poor nutrition. indicative biomarkers, including growth factors and interleukins (ils), reflect biological processes like cell proliferation and tissue remodeling, essential for post-amputation healing. for instance, vascular endothelial growth factor (vegf) supports angiogenesis (blood vessel formation), a key healing component. diagnostic biomarkers, such as alphasmooth muscle actin (α-sma), reveal tissue structure and healing progress at the cellular level. while many biomarkers show potential for improving postamputation healing, their clinical application requires careful validation in amputee populations. biomarkers like wbcs play a key role in immune responses, but elevated wbc counts can be influenced by factors unrelated to wound healing, such as infections or stress. using a biomarker array could better capture all healing stages and account for comorbidities, population differences, and lifestyle factors (e.g. infection, poor nutrition, smoking, alcohol use, gender, and age) known to affect healing. understanding the impact of biomarker quantification, timing and location (e.g. wound fluid or serum) is crucial for clinical optimization. integrating diagnostic biomarkers into clinical practice is challenged by the invasive and complex nature of current measurement techniques. most biomarkers, apart from routine blood markers like cholesterol and wbc counts (which are predictive of healing), remain confined to research due to reliance on techniques like immunohistochemistry requiring tissue samples, raising ethical and logistical barriers. further research must develop accessible, non-invasive diagnostic tools. bridging the gap between experimental research and clinical application is essential to standardize post-amputation healing assessments, reduce subjectivity, and ultimately enhance patient rehabilitation outcomes. acknowledgements the author of this article would like to express appreciation to the strathclyde body device interface mechanobiology research https://doi.org/10.33137/cpoj.v8i1.43717 https://jps.library.utoronto.ca/index.php/cpoj/article/view/43715/33312 https://jps.library.utoronto.ca/index.php/cpoj/article/view/43716/33400 13 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 group for their assistance in the discussion of the review’s methodology. declaration of conflicting interests the author has no conflicts of interest to declare. authors’ contribution • hannelore williams-reid: the primary author of the manuscript, undertook the scoping review and prepared the final manuscript as part of a 4-year phd program. • arjan buis: the primary phd supervisor, assisted in developing the scoping review methodology and preparing the manuscript for publication. • anton johannesson: the secondary phd supervisor, assisted in developing the scoping review methodology and preparing the manuscript for publication. all authors have read and 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of leucine-rich α-2-glycoprotein 1 in cutaneous wound healing under normal and diabetic conditions. diabetes. 2020;69(11):2467-80. doi:10.2337/db20-0585 220.morisaki k, yamaoka t, iwasa k. risk factors for wound complications and 30-day mortality after major lower limb amputations in patients with peripheral arterial disease. vascular. 2018;26(1):12-7. doi:10.1177/1708538117714197 221.nolan gs, smith oj, heavey s, jell g, mosahebi a. histological analysis of fat grafting with platelet-rich plasma for diabetic foot ulcers-a randomised controlled trial. int wound j. 2022;19(2):389-98. doi:10.1111/iwj.13640 https://doi.org/10.33137/cpoj.v8i1.43717 22 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 3 a scoping review of chemical biomarkers. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no.1. https://doi.org/10.33137/cpoj.v8i1.43717 canadian prosthetics & orthotics journal issn: 2561-987x wound management: chemical biomarkers williams-reid et al., 2025 222.nur rosyid f, dharmana e, suwondo a, hs k, sugiarto s. the effect of bitter melon (momordica charantia l.) leaves extract on tnf-α serum levels and diabetic foot ulcers improvement: randomized controlled trial. biomed pharmacol j. 2018;11:141321. doi:10.13005/bpj/1505 223.paul ts, das bb, talekar yp, banerjee s. exploration of the role of a lithophytic fern, pteris vittata l. in wound tissue regeneration and remodelling of genes in hyperglycaemic rat model. clinical phytoscience. 2020;6(1):79. doi:10.1186/s40816020-00223-7 224.pu d, lei x, leng w, zheng y, chen l, liang z, et al. lower limb arterial intervention or autologous platelet-rich gel treatment of diabetic lower extremity arterial disease patients with foot ulcers. ann transl med. 2019;7(18):485. doi:10.21037/atm.2019.07.87 225.ramaprabha p, ramani cp, kesavan r. study on microbiome of chronic non healing diabetic ulcers with special reference to biofilm and multidrug resistant strains. j clin diagn res. 2021. doi:10.7860/jcdr/2021/50126.15471 226.tellechea a, bai s, dangwal s, theocharidis g, nagai m, koerner s, et al. topical application of a mast cell stabilizer improves impaired diabetic wound healing. j invest dermatol. 2020;140(4):901-11.e11. doi:10.1016/j.jid.2019.08.449 227.tkaczyk c, jones-nelson o, shi yy, tabor de, cheng l, zhang t, et al. neutralizing staphylococcus aureus virulence with azd6389, a three mab combination, accelerates closure of a diabetic polymicrobial wound. msphere. 2022;7(3):e0013022. doi:10.1128/msphere.00130-22 228.trejo j, ryan e, khan f, iannuzzi n, chansky h, lack wd. risk factors for failure of limb salvage among veterans with foot ulcers. foot ankle surg. 2022;28(5):584-7. doi:10.1016/j.fas.2021.06.003 229.wang t, zheng y, shi y, zhao l. ph-responsive calcium alginate hydrogel laden with protamine nanoparticles and hyaluronan oligosaccharide promotes diabetic wound healing by enhancing angiogenesis and antibacterial activity. drug deliv transl res. 2019;9(1):227-39. doi:10.1007/s13346-018-00609-8 230.wu t, xie d, zhao x, xu m, luo l, deng d, et al. enhanced expression of mir-34c in peripheral plasma associated with diabetic foot ulcer in type 2 diabetes patients. diabetes metab syndr obes. 2021;14:4263-73. doi:10.2147/dmso.s326066 231.xia g, liu y, tian m, gao p, bao z, bai x, et al. nanoparticles/thermosensitive hydrogel reinforced with chitin whiskers as a wound dressing for treating chronic wounds. j mater chem b. 2017;5(17):3172-85. doi:10.1039/c7tb00479f 232.yadav s, arya dk, pandey p, anand s, gautam ak, ranjan s, et al. ecm mimicking biodegradable nanofibrous scaffold enriched with curcumin/zno to accelerate diabetic wound healing via multifunctional bioactivity. int j nanomedicine. 2022;17:6843-59. doi:10.2147/ijn.s388264 233.ye j, kang y, sun x, ni p, wu m, lu s. microrna-155 inhibition promoted wound healing in diabetic rats. int j low extrem wounds. 2017;16(2):74-84. doi:10.1177/1534734617706636 234.zubair m, ahmad j. transcutaneous oxygen pressure (tcpo(2)) and ulcer outcome in diabetic patients: is there any correlation? diabetes metab syndr. 2019;13(2):953-8. doi:10.1016/j.dsx.2018.12.008 235.baumfeld d, baumfeld t, macedo b, zambelli r, lopes f, nery c. factors related to amputation level and wound healing in diabetic patients. acta ortop bras. 2018;26(5):342-5. doi:10.1590/1413785220182605173445 236.camacho-rodríguez h, guillen-pérez ia, roca-campaña j, baldomero-hernández je, tuero-iglesias á d, galván-cabrera ja, et al. heberprot-p's effect on gene expression in healing diabetic foot ulcers. medicc rev. 2018;20(3):10-4. doi:10.37757/mr2018.v20.n3.4 237.khan ms, tauqeer ahmed m. novel candidates for chronic diabetic wound healing. j pak assoc dermatol. 2022;32(3):526-31. 238.naderi n, zaefizadeh m. expression of growth factors in reepithelialization of diabetic foot ulcers after treatment with nonthermal plasma radiation. biomedical research 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[cited 2024, july 5]. available from: https://www.ncbi.nlm.nih.gov/books/nbk537328/ 276.lin c, liu j, sun h. risk factors for lower extremity amputation in patients with diabetic foot ulcers: a meta-analysis. plos one. 2020;15(9):e0239236. doi:10.1371/journal.pone.0239236 277.lu q, wang j, wei x, wang g, xu y. risk factors for major amputation in diabetic foot ulcer patients. diabetes metab syndr obes. 2021;14:2019-27. doi:10.2147/dmso.s307815 278.yazdanyar a, newman ab. the burden of cardiovascular disease in the elderly: morbidity, mortality, and costs. clin geriatr med. 2009;25(4):563-77, vii. doi:10.1016/j.cger.2009.07.007 https://doi.org/10.33137/cpoj.v8i1.43717 http://www.ncbi.nlm.nih.gov/books/nbk499840/ https://www.bacpar.org/data/resource_downloads/spargreport2019(public).pdf https://www.bacpar.org/data/resource_downloads/spargreport2019(public).pdf https://www.ncbi.nlm.nih.gov/books/nbk560882/ https://www.ncbi.nlm.nih.gov/books/nbk441843/ 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samuel od, badruddin ia. merits and limitations of mathematical modeling and computational simulations in mitigation of covid-19 pandemic: a comprehensive review. arch comput methods eng. 2022;29(2):1311-37. doi:10.1007/s11831-021-09634-2 292.white a, tolman m, thames hd, withers hr, mason ka, transtrum mk. the limitations of model-based experimental design and parameter estimation in sloppy systems. plos comput biol. 2016;12(12):e1005227. doi:10.1371/journal.pcbi.1005227 293.menon sn, flegg ja. mathematical modeling can advance wound healing research. adv wound care (new rochelle). 2021;10(6):328-44. doi:10.1089/wound.2019.1132 294.paez a. gray literature: an important resource in systematic reviews. j evid based med. 2017;10(3):233-40. doi:10.1111/jebm.12266 abbreviations & acronyms: abbreviations & acronyms definition bli bioluminescence imaging ccl chemokine (c-c motif) ligand cd cluster of differentiation crp c-reactive protein dfu diabetic foot ulcer dna deoxyribonucleic acid egf epidermal growth factor elisa enzyme-linked immunosorbent assay enos endothelial nitric oxide synthase erk extracellular signal-regulated kinase esr erythrocyte sedimentation rate fbs fasting blood sugar freq. frequency fgf fibroblast growth factor hb hemoglobin hba1c hemoglobin a1c (glycated hemoglobin) hct hematocrit hdl high-density lipoprotein hif1-α hypoxia-inducible factor 1 alpha ifn interferon igf insulin-like growth factor il interleukin inos inducible nitric oxide synthase jbi joanna briggs institute ki-67 antigen kiel 67 ldl low-density lipoprotein mcp monocyte chemoattractant protein mmp matrix metalloproteinases mpo myeloperoxidase na not applicable nadph nicotinamide adenine dinucleotide phosphate nf-κb nuclear factor kappa-light-chain-enhancer of activated b cells no. number pdgf platelet-derived growth factor prisma-scr preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews qrt-pcr quantitative reverse transcription polymerase chain reaction rct randomized controlled trial refs. references rna ribonucleic acid ros reactive oxygen species sparg scottish physiotherapy amputee research group tgf transforming growth factor timps tissue inhibitor of metalloproteinase tma transmetatarsal amputation tmr® therapeutic magnetic resonance tnf tumor necrosis factor usa united states of america vegf vascular endothelial growth factor wbc white blood cells α-sma alpha-smooth muscle actin https://doi.org/10.33137/cpoj.v8i1.43717 https://assets.publishing.service.gov.uk/media/5a82c07340f0b6230269c82d/diabetesprevalencemodelbriefing.pdf https://assets.publishing.service.gov.uk/media/5a82c07340f0b6230269c82d/diabetesprevalencemodelbriefing.pdf https://www.ukri.org/news/use-of-both-sexes-to-be-default-in-laboratory-experimental-design/ https://www.ukri.org/news/use-of-both-sexes-to-be-default-in-laboratory-experimental-design/ all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 1 2025 research article pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i1.44416 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 research article impact of amputation level and vaulting on loading parameters during level ground walking pröbsting e1*, schmalz t1, bellmann m1, 2 1. clinical research and services, research biomechanics, ottobock se & co. kgaa, göttingen, germany. 2. hawk university of applied sciences and arts göttingen, germany. introduction during the rehabilitation process after a lower limb amputation, one of the most important goals is the restoration of standing and level ground walking. several studies have investigated level walking in individuals with lower limb amputation1-8 and compared their gait to that of able-bodied individuals.1,2,7,8 most of these studies have analyzed effects of different prosthetic components, mainly different prosthetic feet3 and prosthetic knee joints,4,5 on improving safety and mobility. a small number of studies also analyzed possibilities and limitations of different prosthetic hip joints.6,9 studies have shown that gait asymmetry is common in people with lower limb amputation.1,2 compared to ablebodied individuals, people with lower limb amputation generally walk slower, including a prolonged stance phase duration on their contralateral limb compared to the residual one and to able-bodied individuals.1,8 nolan and lees7 have shown that people with amputation compensate the loss of one or more joints by increased net joint moments and power output at their contralateral ankle, knee and hip joint compared to able-bodied individuals.1,10 pröbsting et al., found no increased joint moments on the contralateral limb in people with tt amputation.8 the asymmetry in step length and stance phase duration increases with higher amputation level.2 however, the literature shows that individuals with tt amputation can still achieve a gait pattern similar to that of able-bodied individuals1,2,7,8 as they can actively control their knee joint,8 compared to those with tf and hd amputation.5,6 studies open access abstract background: previous studies show that during level walking, the load on the contralateral side increases with more proximal amputation levels. furthermore, a typical compensation mechanism, vaulting on the contralateral side, may also influence the load. however, no study has compared the load applied to the contralateral side across more than two different amputation levels. objective: the objectives of this study were to analyze the biomechanical impact of different lower limb amputation levels and vaulting on the load applied to the locomotor system. methodology: gait data from 82 individuals with different amputation levels (44 transtibial (tt), 30 transfemoral (tf), and 8 hip disarticulation (hd)) were retrospectively analyzed in this study. peak knee adduction, flexion and extension moments, vertical ground reaction force peaks, and force rates were statistically analyzed between different amputation levels and between two groups “tf with vaulting” and “tf without vaulting”. findings: as the level of amputation increases, walking speed decreases and asymmetry of stance duration increases. tf individuals with vaulting tend to walk faster than those without vaulting. the first peak of vertical ground reaction forces, the peak knee adduction and extension moments increase, and the peak knee flexion moments decrease with higher amputation level. the higher the amputation level, the curve of the vertical ground reaction force becomes significantly steeper during the first 5% of the gait cycle (gc). the first peak of ground reaction forces, the knee flexion, extension and adduction moments tend to be higher in tf individuals with vaulting. conclusion: in summary, a higher lower limb amputation level can increase loading on the contralateral limb and contribute to a higher incidence of vaulting during gait. the effect of vaulting as a compensation pattern leads to an additional increase in contralateral limb loading. article info received: november 27, 2024 accepted: february 28, 2025 published: march 7, 2025 citation pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v 8i1.44416 keywords amputation; lower limb amputation; level walking; vaulting; biomechanics; gait; transtibial; transfemoral; hip disarticulation; knee; ground reaction force; gait analysis * corresponding author: eva pröbsting, dipl.-ing (fh) affiliation: clinical research and services, research biomechanics, ottobock se & co. kgaa, göttingen, germany. e-mail: eva.proebsting@ottobock.de orcid id: https://orcid.org/0000-0002-6349-2992 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 1, article no. 2. 2025 https://doi.org/10.33137/cpoj.v8i1.44416 https://doi.org/10.33137/cpoj.v8i1.44416 https://doi.org/10.33137/cpoj.v8i1.44416 mailto:eva.proebsting@ottobock.de https://orcid.org/0000-0002-6349-2992 https://jps.library.utoronto.ca/index.php/cpoj/index 2 pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 canadian prosthetics & orthotics journal issn: 2561-987x impact of amputation level and vaulting on gait loading parameters pröbsting et al., 2025 state a more asymmetric gait, with prolonged stance phase duration and increased load on the contralateral side, in individuals with tf amputation compared to those with tt amputation.7,11,12 the latter explains the increased risk of contralateral knee joint osteoarthritis in individuals with tf amputation,13 as the increase in frontal and sagittal knee moments, and ground reaction forces, could contribute to development of knee joint degeneration in able-bodied individuals.14-16 able-bodied individuals are able to control the distance between the foot and the ground (foot clearance) through the coordination of ankle dorsiflexion, knee joint flexion and hip joint flexion.17,18 missing active dorsiflexion (in tts, tfs, and hds), active knee joint flexion (in tfs and hds) and/or active hip joint flexion (hds) affect foot clearance. catching the ground with the prosthetic foot can result in a fall. in order to reduce the risk of falling, individuals with lower limb amputation develop compensatory strategies, such as vaulting, hip hiking and circumduction,19 which could lead to gait asymmetry. vaulting is the most prevalent method described by people with lower limb amputation and clinicians, yet it is not often discussed in the literature. smith et al. described vaulting as “a premature midstance plantar flexion by the contralateral limb which assists toe clearance of the prosthetic limb by lifting the body”.20 in a big cohort of individuals with different lower limb amputation levels, vaulting occurred more frequently with higher amputation level,2 but no further analysis was conducted. drevelle et al21 used quantitative gait analysis to evaluate vaulting motion pattern in individuals with tf amputation. those who use vaulting as a compensatory movement exhibited a higher peak in generated power at the contralateral ankle during the contralateral single stance phase.21 subsequently, vaulting and the level of amputation seem to influence the load on the contralateral side. to the knowledge of the authors, no study has yet analyzed the contralateral load for more than two different amputation levels and only one study has analyzed the influence of vaulting on the contralateral single stance phase.21 therefore, the purpose of the present study was to describe the biomechanical effects of different amputation levels and vaulting on the loading parameters of the contralateral side, specially knee joint moments and vertical ground reaction force. the primary hypothesis was that as the level of amputation increases, the load on the contralateral side also increases during stance. the secondary hypothesis was that vaulting increases load on the contralateral side compared to non-vaulters between mid-stance to preswing. methodology data collection gait data from 82 individuals with different lower limb amputation levels were retrospectively analyzed in this study. gait analyses have been conducted at ottobock's gait lab in göttingen since 2002. gait data were captured using a vicon system (8 m-cams with measurement frequency 100hz till 2013 and subsequent 12 bonita cams (200hz), vicon peak, oxford, gb) coupled with two force plates (measurement frequency 1000hz; kistler 9287a, winterthur, ch). the study was conducted according to the declaration of helsinki regarding human medical experimentation and entirely complies with the requirements of the german medical device act as well as the data protection law. subjects gave their full verbal consent being measured and that pseudonymized data can be used for retrospective analyses and publication. the biomechanical data used for this retrospective analysis were recorded from patients fitted in an orthopedic workshop. measurements were taken at the end of the fitting process for documentation and quality assurance of the regular everyday fitting. the following inclusion criteria were used in this study: • individuals with unilateral amputation (tt, tf (no short stump ≤ 1/3 of contralateral femur length) or hd). • age > 18 years. • no additional health impairment. • able to walk at a self-selected velocity on level ground. • use of a commercially available energy storing and returning (esr) foot. • tf prosthesis with genium knee joint. • hd prosthesis with c-leg knee joint and helix3d hip joint. • prosthesis aligned according to the criteria defined by blumentritt22 for tts and bellmann for tfs23 and hd.24 furthermore, the group of tfs was divided into two groups: “tf with vaulting”, and “tf without vaulting”. to make this differentiation, we used the method described by drevelle,21 assuming that people with ankle flexion power values higher than 0.15 w/kg during single stance support conduct vaulting.21 data analysis three-dimensional marker trajectories were tracked from 17 markers placed on anatomical landmarks (both sides: acromion, epicondylus lateralis humeri, processus styloideus ulnare, trochanter major, compromise knee centre of rotation according to nietert,25 malleolus lateralis, caput os metatarsale iv; and three asymmetric markers: left tibia, right thigh and left shoulder blade). this marker set has been used since 1998 and was created to analyze essential gait parameters for people with amputation.8 external joint moments were calculated based on ground reaction forces and coordinates of the joint centers as described in a previous study.8 https://doi.org/10.33137/cpoj.v8i1.44416 3 pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 canadian prosthetics & orthotics journal issn: 2561-987x impact of amputation level and vaulting on gait loading parameters pröbsting et al., 2025 in order to quantify the load on the contralateral leg, to test both hypotheses, the vertical ground reaction force and the external sagittal and frontal moments acting on the contralateral knee joint were evaluated.14-16 the first and second peak of the vertical ground reaction forces, the peak flexion and extension knee moments and the first peak of the frontal knee moments were identified and statistically analyzed. furthermore, the assessment of the force increase characteristic is a frequently used parameter to evaluate the load on the contralateral side.26-29 it is known from studies of running that a steeper increase correlates with a higher risk of injury.26,29 there are various analysis options for this parameter.26 in the present study, to test the first hypothesis, the increase of the vertical ground reaction force in the first 5% gait cycle (gc) was determined by the difference between the first value and the value at 5% gc. moreover, spatiotemporal gait parameters were reported as well. all kinetic data were normalized to the stance phase of the gait cycle. statistical analysis mean values for all parameters were determined based on 8 to 12 single gait cycles for the contralateral limb. group means were calculated based on the values of all tts, tfs and hds and also for the two groups “tf with vaulting” and “tf without vaulting”. the kolmogorov-smirnov test was used to analyze the normal distribution of the data. afterwards, the bartlett's test was used to identify whether equal variances exist. since these two requirements were met, the differences in the peak values of biomechanical parameters and spatiotemporal gait parameters between the amputee groups were tested with the one-way anova for each evaluated parameter. post-hoc analyses with bonferroni’s corrections were performed when anova showed significant differences. the significance level was set at p < 0.05. all analyses were performed using the winstat software (version 2012.1.0.96). results participants data from 44 tts, 30 tfs and 8 hds were used for the analysis. detailed information about the participants is shown in table 1. the individuals with tt, tf, and hd amputation had an average age of 47 (sd=15), 45 (sd=14), and 43 (sd=12) years, respectively. their average heights were 176 cm (sd=13), 183 cm (sd=5), and 175 cm (sd=10), while their respective weights, measured with the prosthesis, were 88 kg (sd=24), 84 kg (sd=9), and 76 kg (sd=16). using the method of drevelle,21 12% of the tts, 63% of the tfs and all hds vaulted. table 1: participant anthropometric data. amputation level tt tf hd number of patients 44 30 8 age [years]* 47 ± 15 45 ± 14 43 ± 12 height [cm]* 176 ± 13 183 ± 5 175 ± 10 weight [kg]* 88 ± 24 84 ± 9 76 ± 16 vaulting rate** 12% 63% 100% * mean ± sd; ** determined based on the assumption that the ankle power on the sound side is > 0.15 w/kg. spatiotemporal gait parameters as the level of amputation increases, walking speed decreases from 1.31 ± 0.17 m/s to 1.13 ± 0.16 m/s with no significant differences across all amputation levels. vaulting tfs tend to walk faster than tfs without vaulting (1.28 ± 0.19 m/s vs. 1.22 ± 0.11 m/s). likewise, the length of the stance phase decreases on the prosthetic side and increases on the contralateral side in correspondence with a more proximal amputation level. only a few differences are statistically significant (table 2). however, the asymmetry of the stance phase duration differed significantly between all amputation levels. the tts show the lowest asymmetry with 2.7 ± 2.0% gc, while the hds show the greatest with 9.3 ± 4.5% gc. in terms of step length asymmetry, the hd group differs significantly from all amputation levels as well as from the tfs with and without vaulting. this group is the only one showing longer step lengths on the contralateral side than on the prosthetic side (table 2). vertical ground reaction forces the values of the first and second peak of the contralateral vertical ground reaction forces did not show any significant differences between the amputation levels nor between the two tf groups (figure 1). however, there is a tendency that the first peak increases with a higher amputation level (tts: 115 ± 11% bw, tfs: 115 ± 10% bw, hds: 117 ± 9% bw) and also in the tfs with vaulting (118 ± 10% bw vs. 109 ± 9% bw). esr esr genium c-leg helix esr https://doi.org/10.33137/cpoj.v8i1.44416 4 pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 canadian prosthetics & orthotics journal issn: 2561-987x impact of amputation level and vaulting on gait loading parameters pröbsting et al., 2025 table 2: spatiotemporal gait parameters and statistical data for all three amputation levels and the two subgroups, “tf with vaulting” and “tf without vaulting”. tt tf hd tf without vaulting tf with vaulting significant differences p<0.05 velocity [m/s] 1.31 ± 0.17 1.26 ± 0.16 1.13 ± 0.16 1.22 ± 0.11 1.28 ± 0.19 not significant stance duration sound side [%gait cycle] 64.3 ± 2.1 65.1 ± 2.2 67.6 ± 3.3 65.6 ± 1.8 64.9 ± 2.3 hd vs. tt hd vs. tf with vaulting stance duration prosthetic side [%gait cycle] 61.7 ± 1.4 59.3 ± 1.8 58.5 ± 2.2 59.9 ± 1.5 58.9 ± 1.8 hd vs. tt hd vs. tf hd vs. tf without vaulting hd vs. tf with vaulting asymmetry stance duration sound side prosthetic side [%gait cycle] 2.7 ± 2.0 5.9 ± 2.2 9.3 ± 4.5 5.6 ± 2.8 6.0 ± 1.9 tt vs. tf tt vs. tf without vaulting tt vs. tf with vaulting tt vs. hd hd vs. tf hd vs. tf without vaulting hd vs. tf with vaulting step length sound side [m] 0.69 ± 0.07 0.69 ± 0.06 0.71 ± 0.06 0.67 ± 0.05 0.70 ± 0.07 not significant step length prosthetic side [m] 0.74 ± 0.08 0.74 ± 0.08 0.66 ± 0.08 0.73 ± 0.05 0.74 ± 0.09 not significant asymmetry step length sound side prosthetic side [m] -0.05 ± 0.05 -0.04 ± 0.06 +0.05 ±0.07 -0.06 ± 0.05 -0.03 ± 0.07 hd vs. tt hd vs. tf hd vs. tf without vaulting hd vs. tf with vaulting figure 1: top: mean course of contralateral vertical ground reaction force (time normalized) for all three amputation levels (upper left) and the two subgroups, “tf with vaulting” and “tf without vaulting” (upper right). bottom: relevant peak values with statistical data. 0 20 40 60 80 100 120 0 10 20 30 40 50 60 70 80 90 100 v e rt ic a l g ro u n d r e a c ti o n f o rc e [ % b w ] t [% stance phase] tf without vaulting contralateral tf with vaulting contralateral 0 20 40 60 80 100 120 0 10 20 30 40 50 60 70 80 90 100 v e rt ic a l g ro u n d r e a c ti o n f o rc e [ % b w ] t [% stance phase] tt contralateral tf contralateral hd contralateral a b c v e rt ic a l g ro u n d r e a c ti o n f o rc e [% b w ] 90 100 110 120 130 140 150 160 1.max grf v tt sound side tf sound side hd sound side series4 tf sound side without vaulting tf sound side with vaulting v e rt ic a l g ro u n d r e a c ti o n f o rc e [% b w ] 0 20 40 60 80 100 120 140 grf v: force-rate in the first 5% gait cycle not significant n.s.* ** * * * * a b c v e rt ic a l g ro u n d r e a c ti o n f o rc e [% b w ] 80 90 100 110 120 130 140 2.max grf v c not significant tt sound side tf sound side hd sound side tf sound side without vaulting tf sound side with vaulting https://doi.org/10.33137/cpoj.v8i1.44416 5 pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 canadian prosthetics & orthotics journal issn: 2561-987x impact of amputation level and vaulting on gait loading parameters pröbsting et al., 2025 in contrast, the force rate during the first 5% gait cycle differed significantly between all amputation levels. the higher the amputation level, the steeper the force rate (hds: 98 ± 14% bw, tfs: 79 ± 14% bw and tts: 67 ± 15% bw). in conclusion, the first peak was reached earlier with higher amputation levels. contralateral sagittal knee moments in the hds group, there was a general trend towards increased extension moments on the contralateral knee compared to tts and tfs. as the amputation level increased, the peak flexion moments tend to decrease, (tts: -0.50 ± 0.28 nm/kg, tfs: -0.46 ± 0.30 nm/kg, hds: 0.27 ± 0.38 nm/kg), whereas the peak extension moment increased (tts: 0.51 ± 0.19 nm/kg, tfs: 0.60 ± 0.29 nm/kg, hds: 0.76 ± 0.20 nm/kg). the tfs without vaulting showed a reduced peak flexion moment (-0.28 ± 0.24 nm/kg vs. 0.56 ± 0.29 nm/kg) and a reduced peak extension moment (0.46 ± 0.32 nm/kg vs. 0.68 ± 0.24 nm/kg). all differences are statistically not significant (figure 2). contralateral frontal knee moments generally, the peak adduction moment (first peak for all subjects) increases with a more proximal amputation level (tts: 0.51 ± 0.19 nm/kg, tfs: 0.55 ± 0.20 nm/kg, hds: 0.57 ± 0.14 nm/kg). the tfs with vaulting also show an increased peak compared to those without vaulting (0.57 ± 0.22 nm/kg vs. 0.53 ± 0.16 nm/kg). nevertheless, none of these differences show statistical significance (figure 3). discussion the objectives of this study were to analyze the biomechanical impact of different lower limb amputation levels and vaulting on the load applied to the locomotor system. the higher the amputation level, the curve of the vertical ground reaction force becomes significantly steeper during the first 5% gc. the first peak of vertical ground reaction forces, the peak knee adduction and extension moments tend to be higher both in individuals with higher amputation level and in tf individuals with vaulting. figure 2: top: mean course of external contralateral sagittal knee moments (time normalized) for all three amputation levels (upper left) and the two subgroups, “tf with vaulting” and “tf without vaulting” (upper right); bottom: selected peak values with statistical data. -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 0 10 20 30 40 50 60 70 80 90 100 s a g it ta l k n e e m o m e n t [n m /k g ] t [% stance phase] tf without vaulting sound side tf with vaulting sound side external knee flexion moment + external knee extension moment -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 0 10 20 30 40 50 60 70 80 90 100 s a g it ta l k n e e m o m e n t [n m /k g ] t [% stance phase] tt sound side tf sound side hd sound side + external knee extension moment external knee flexion moment a b s a g it ta l k n e e m o m e n t [n m /k g ] -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 max. knee flexion moment a s a g it ta l k n e e m o m e n t [n m /k g ] 0 0.2 0.4 0.6 0.8 1 1.2 1.4 max. knee extension moment b not significantnot significant tf sound side with vaulting tf sound side without vaulting hd sound side tf sound side tt sound side https://doi.org/10.33137/cpoj.v8i1.44416 6 pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 canadian prosthetics & orthotics journal issn: 2561-987x impact of amputation level and vaulting on gait loading parameters pröbsting et al., 2025 peak knee flexion moments decreased with higher amputation levels and tended to be higher in tf individuals with vaulting. individuals with lower limb amputation have an increased risk of developing knee joint degeneration.13 therefore, any increase in knee joint loading forces and moments is clinically relevant. for this reason, the nonsignificant increases in forces and moments observed in this study, are still clinically important. primary hypothesis: load on the contralateral side increases with higher amputation level. during the first 5% gait cycle, the vertical ground reaction force increased significantly faster with a more proximal amputation level, although the walking speed decreased accordingly. this interrelation between force rate and walking speed is untypical. typically, the increase in vertical ground reaction force becomes steeper as walking speed increases.30 the prosthetic limb exhibited a reduced stance and prolonged swing duration. as noted by ding et al.,31 this may contribute to a more abrupt “landing” on the contralateral limb, evidenced by a significantly greater peak knee loading rate and a significant increased force rate observed in this study. subsequently, the first peak of vertical ground reaction force was increased with higher amputation level. this, in turn, impacted the first peak knee adduction moment, which was also slightly increased with higher amputation level, but more pronouncedly. based on these effects, it can be concluded that knee compression forces were also increased.32 thus, the shortened prosthetic stance phase contributed to an increased load on the contralateral side. this should be avoided by an optimally aligned prosthesis, adequate prosthetic components and appropriate gait training. increased knee extension, or rather less knee flexion moments, were identified for higher amputation levels, both at the beginning and at the end of stance. although these peaks are not significantly different, a clear and systematical tendency can be observed with a higher amputation level. the missing significance might be in relation to the speed differences within each group. all individuals in this study, independent of their level of amputation, showed a prolonged stance phase duration on the contralateral side compared to the prosthetic side. this leaded to an asymmetric stance phase duration, as confirmed by other studies comparing tts and tfs with able-bodied individuals1 and with each other.7 figure 3: top: mean course of external contralateral frontal knee moments (time normalised) for all three amputation levels (upper left) and the two subgroups, tf with vaulting” and “tf without vaulting” (upper right). bottom: selected peak values with statistical data. -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0 10 20 30 40 50 60 70 80 90 100f ro n ta l k n e e m o m e n t [n m /k g ] t [% stance phase] tt sound side tf sound side hd sound side a -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0 10 20 30 40 50 60 70 80 90 100 f ro n ta l k n e e m o m e n t [n m /k g ] t [% stance phase] tf without vaulting sound side tf with vaulting sound side f ro n ta l k n e e m o m e n t [n m /k g ] 0 0.2 0.4 0.6 0.8 1 1.2 1.4 max. knee adduction moment a not significant tf sound side with vaulting tf sound side without vaulting hd sound side tf sound side tt sound side https://doi.org/10.33137/cpoj.v8i1.44416 7 pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 canadian prosthetics & orthotics journal issn: 2561-987x impact of amputation level and vaulting on gait loading parameters pröbsting et al., 2025 the results of the present study confirmed the results of heitzmann et al.2 and showed that asymmetric stance phase duration significantly differed across all amputation level, with tts showing the smallest and hds showing the greatest asymmetry. therefore, the contralateral limb experienced comparatively higher loading over a significantly longer time with a higher amputation level. thus, it can be assumed that the significantly longer loading duration, combined with the significant faster load transmission and higher ground reaction forces, as well as sagittal and frontal moments, explain the higher prevalence of knee osteoarthritis13 with higher amputation level. consequently, the primary hypothesis of the present study stating that a more proximal amputation level increases the load on the contralateral side is confirmed by the results. secondary hypothesis: vaulting increased the load on the contralateral side. in comparison with able-bodied individuals, prosthesis users experience a reduced ability to actively control the prosthesis with the residual limb as the level of amputation increases (from tt to hd), and their strategies for achieving ground clearance become more limited. as a result, the contralateral side is used more intensively for compensation with vaulting being the most obvious and specific strategy. this strategy was observed in all hds, 63% of the tfs and only 12% of the tts in the present study. increased vaulting with higher amputation level is a logical and sometimes necessary consequence and was already observed by heitzmann et al.2 some highly functional and safe prosthetic components, e.g. more functional hip joints,6 microprocessor knee joints33 and hydraulic ankle joints,3 support the generation of more ground clearance. but one of the main influencing factors is prosthetic alignment, specifically the anterior-posterior position of the knee joint axis of rotation and the foot.33 furthermore, people with lower limb amputation rely on the ground clearance provided by the prosthesis without any sensory feedback. the prosthesis may not perform optimally especially in unpredictable situations and therefore patient-initiated vaulting is understandable. besides contralateral forefoot pain, this compensation strategy could lead to biomechanical consequences, such as higher energy consumption than able-bodied individuals and an asymmetric loading distribution, with increased ground reaction forces on the contralateral limb.21 furthermore, vaulting can also lead to increased ankle, knee and hip moments on the contralateral limb at the end of stance phase.7 for a more detailed analysis of the impact of vaulting on the loading of the locomotor system, the tf patient group was divided into two groups with and without vaulting. a similar separation was not useful for the other amputation levels. in the hd group, all individuals performed vaulting. in the tts, the group with vaulting was too small compared to the “nonvaulting” group. the following analyzed peak values were increased for the tfs with vaulting: first and second peak ground reaction forces, first peak knee adduction moment, max. knee flexion and max. knee extension moment. the most obvious difference between the two groups was found in the sagittal plane. on the one hand, tfs with vaulting showed more stance flexion,21 which could explain the higher knee flexion moments in the first part of stance. on the other hand, the faster anterior movement of the center of pressure (cop)21 and the prominent extension of the knee joint at the end of stance21 could explain the increased extension moments.7,21 generally, walking speed influences the magnitude of joint moment peaks,34 and the tf group with vaulting walked 0.06m/s faster than non-vaulting group. according to lelas et al.,34 this speed difference could explain an increase in the peak knee flexion moment by 0.02 nm/kg and the peak knee extension moments by 0.003 nm/kg. however, the difference in the peak knee flexion moment between the two groups of tfs was 0.20 nm/kg and the difference in the peak knee extension moment was 0.22 nm/kg, both of which were more pronounced. therefore, the increase of knee joint moments for tfs with vaulting can be clearly attributed to this compensatory motion. nevertheless, the secondary hypothesis that vaulting influences the load on the contralateral side can be confirmed to a certain extent as the results were not statistically significant, but were clinically relevant for patients showing unusually high loads. limitation the limitations of this study were, on the one hand, the different number of subjects with the respective amputation levels. the small number of people with hd amputation was a particular limitation in this study. on the other hand, determining the effect of vaulting was challenging when comparing two different cohorts of people with tf amputation, as individual knee moment heights were highly subject-specific. in order to reduce the latter limitation, an analysis of able-bodied individuals walking with and without vaulting should be conducted in future studies. this could provide a more detailed understanding of the specific effect of vaulting on knee joint moments. conclusion in summary, the loading of the contralateral limb increases with higher amputation level. the increase of knee loading is caused by the reduced stance duration of the amputated side with a fast force transmission onto the contralateral side in the first phase of stance. the effect of vaulting as a compensation pattern leads to an additional increase of https://doi.org/10.33137/cpoj.v8i1.44416 8 pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 canadian prosthetics & orthotics journal issn: 2561-987x impact of amputation level and vaulting on gait loading parameters pröbsting et al., 2025 contralateral limb loading. as the level of amputation increases, the ratio of vaulting in amputees increases, which means that the contralateral load also increases with the level of amputation. therefore, the aim of gait training, prosthetic alignment and the selection of prosthetic components should support a more symmetric gait without or with only moderate compensatory vaulting patterns. acknowledgements the authors thank the participants whose data were retrospectively analyzed for their valuable contribution. declaration of conflicting interests eva pröbsting, thomas schmalz and malte bellmann are employees of ottobock, the manufacturer of prosthetic components. the authors alone are responsible for the content and writing of the paper. authors contribution • eva pröbsting: investigated, analyzed the data and wrote the manuscript. • thomas schmalz: investigated, analyzed the data and reviewed • malte bellmann: investigated, analyzed the data and reviewed. all authors have read and approved the final version of the manuscript. sources of support the authors received no support. references 1.schmid m, beltrami g, zambarbieri d, verni g. centre of pressure displacements in trans-femoral amputees during gait. gait posture. 2005;21(3):255-62. doi: 10.1016/j.gaitpost.2004.01.016 2.heitzmann dww, block j, braatz f, wolf si, alimusaj m. gangmuster von amputierten in abhängigkeit vom amputationsniveau [gait patterns of amputees depending on the amputation level]. orthopädie technik, 2013. 64 (3): 14–19 3.johnson l, de asha ar, munjal r, kulkarni j, buckley jg. toe clearance when walking in people with unilateral transtibial amputation: effects of passive hydraulic ankle. j rehabil res dev. 2014;51(3):429-37. doi: 10.1682/jrrd.2013.05.0126 4.thiele j, westebbe b, bellmann m, kraft m. designs and performance of microprocessor-controlled knee joints. biomed tech (berl). 2014;59(1):65-77. doi: 10.1515/bmt-2013-0069 5.bellmann m, köhler tm, schmalz t. comparative biomechanical evaluation of two technologically different microprocessorcontrolled prosthetic knee joints in safety-relevant daily-life situations. biomed tech (berl). 2019;64(4):407-420. doi: 10.1515/bmt-2018-0026 6.ludwigs e, bellmann m, schmalz t, blumentritt s. biomechanical differences between two exoprosthetic hip joint systems during level walking. prosthet orthot int. 2010;34(4):449-60. doi: 10.3109/03093646.2010.499551 7.nolan l, lees a. the functional demands on the intact limb during walking for active trans-femoral and trans-tibial amputees. prosthet orthot int. 2000;24(2):117-25. doi: 10.1080/03093640008726534 8.pröbsting e, bellmann m, schmalz t, hahn a. gait characteristics of transtibial amputees on level ground in a cohort of 53 amputees – comparison of kinetics and kinematics with nonamputees. can prosthet orthot j. 2020;2(2):32955. doi: 10.33137/cpoj.v2i2.32955 9.lundt je, littig dh, choi ge. das essa3d hüftexartikulationsgelenksystem und sein einfluß auf den energiebedarf bei einseitig amputierten. [the essa 3d hip disarticulation joint system and its influence on energy requirements in unilateral amputees] orthopädie-technik 1995; (9): 773–785 10.jarvis hl, reeves nd, twiste m, phillip rd, etherington j, bennett an. can high-functioning amputees with state-of-the-art prosthetics walk normally? a kinematic and dynamic study of 40 individuals. ann phys rehabil med. 2021;64(1):101395. doi: 10.1016/j.rehab.2020.04.007 11.varrecchia t, serrao m, rinaldi m, ranavolo a, conforto s, de marchis c, et al. common and specific gait patterns in people with varying anatomical levels of lower limb amputation and different prosthetic components. hum mov sci. 2019;66:9-21. doi: 10.1016/j.humov.2019.03.008 12.keklicek h, kirdi e, yalcin a, topuz s, ulger o, erbahceci f, et al. comparison of gait variability and symmetry in trained individuals with transtibial and transfemoral limb loss. j orthop surg (hong kong). 2019;27(1). doi:10.1177/2309499019832665 13.pröbsting e, blumentritt s, kannenberg a. veränderungen am bewegungsapparat als folge von amputationen an der unteren extremität [changes in the locomotor system as a consequence of amputation of a lower limb]. z orthop unfall. 2017;155(1):77-91. german. doi: 10.1055/s-0042-112821 14.manal k, gardinier e, buchanan ts, snyder-mackler l. a more informed evaluation of medial compartment loading: the combined use of the knee adduction and flexor moments. osteoarthr. cartil. 2015: 23(7): 1107-1111. doi:10.1016/j.joca.2015.02.779 15.mündermann a, dyrby co, andriacchi tp. secondary gait changes in patients with medial compartment knee osteoarthritis: increased load at the ankle, knee, and hip during walking. arthritis rheum. 2005; 52(9): 2835-44. doi:10.1002/art.21262 16.hurwitz de, ryals ab, case jp, block ja, andriacchi tp. the knee adduction moment during gait in subjects with knee osteoarthritis is more closely correlated with static alignment than radiographic disease severity, toe out angle and pain. j orthop res. 2002; 20(1): 101-7. doi:10.1016/s0736-0266(01)00081-x 17.rosenblatt nj, bauer a, grabiner md. relating minimum toe clearance to prospective, self-reported, trip-related stumbles in the community. prosthet orthot int. 2017;41(4):387-392. doi: 10.1177/0309364616650085 18.mufadal a. moosabhoy, steven a. gard. methodology for determining the sensitivity of swing leg toe clearance and leg length https://doi.org/10.33137/cpoj.v8i1.44416 9 pröbsting e, schmalz t, bellmann m. impact of amputation level and vaulting on loading parameters during level ground walking. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 2. https://doi.org/10.33137/cpoj.v8i1.44416 canadian prosthetics & orthotics journal issn: 2561-987x impact of amputation level and vaulting on gait loading parameters pröbsting et al., 2025 to swing leg joint angles during gait. gait & posture. 2006; 24(4); 493-501. doi:10.1016/j.gaitpost.2005.12.004 19.villa c, drevelle x, bonnet x, lavaste f, loiret i, fodé p, pillet h. evolution of vaulting strategy during locomotion of individuals with transfemoral amputation on slopes and cross-slopes compared to level walking. clin biomech (bristol). 2015;30(6):6238. doi: 10.1016/j.clinbiomech.2015.03.022 20.smith, d.g., michael, j.w., bowker, j.h., 2002. atlas of amputations and limb deficiencies. american academy of orthopaedic surgeons. isbn 978-1975184452 21.drevelle x, villa c, bonnet x, loiret i, fodé p, pillet h. vaulting quantification during level walking of transfemoral amputees. clin biomech (bristol, avon). 2014;29(6):679-83. doi: 10.1016/j.clinbiomech.2014.04.006 22.blumentritt s. a new biomechanical method for determination of static prosthetic alignment. prosthet orthot int. 1997;21(2):107-13. doi: 10.3109/03093649709164538 23.bellmann m, blumentritt s, pusch m, schmalz t, schönemeier m. das 3d l.a.s.a.r. – eine neue generation der statik-analyse zur optimierung des aufbaus von prothesen und orthesen [the 3d l.a.s.a.r. – a new generation of static analysis for optimising prosthetic and orthotic alignment]. orthopädie technik. 2017; 68 (12): 18–25 24.bellmann m., ludwigs e., blumentritt s. die tms-methode zum aufbau von beckenkorbprothesen [the tms alignment method for pelvic socket style prostheses]. orthopädie technik. 2012; 4 (12): 30–41 25.nietert m. the compromise pivot axis of the knee joint: studies of the kinematics of the human knee joint in regard to their approximation in prosthetics. shaker; isbn-10: 3832273883; 2008 26.napier c, maclean cl, maurer j, taunton je, hunt ma. kinematic correlates of kinetic outcomes associated with runningrelated injury. j appl biomech. 2019;35(2):123-130. doi: 10.1123/jab.2018-0203 27.phan x, grisbrook tl, wernli k, stearne sm, davey p, ng l. running quietly reduces ground reaction force and vertical loading rate and alters foot strike technique. j sports sci. 2017;35(16):1636-1642. doi: 10.1080/02640414.2016.1227466 28.breine b, malcolm p, van caekenberghe i, fiers p, frederick ec, de clercq d. initial foot contact and related kinematics affect impact loading rate in running. j sports sci. 2017;35(15):15561564. doi: 10.1080/02640414.2016.1225970 29.abolins v, nesenbergs v, e bernans e. reliability of loading rate in gait analysis. iop conf ser: mater sci eng. 2019; 575 012002 30.cook tm, farrell kp, carey ia, gibbs jm, wiger ge. effects of restricted knee flexion and walking speed on the vertical ground reaction force during gait. j orthop sports phys ther. 1997; 25(4): 236-244 31.ding z, jarvis hl, bennett an, baker r, bull amj. higher knee contact forces might underlie increased osteoarthritis rates in high functioning amputees: a pilot study. j orthop res. 2021;39(4):850860. doi: 10.1002/jor.24751 32.holder j, trinler u, meurer a, stief f. a systematic review of the associations between inverse dynamics and musculoskeletal modeling to investigate joint loading in a clinical environment. front bioeng biotechnol. 2020;8:603907. doi: 10.3389/fbioe.2020. 603907 33.köhler tm, bellmann m, blumentritt s. polycentric exoprosthetic knee joints – extent of shortening during swing phase. can prosthet orthot j. 2020;3(1):33768. doi: 10.33137/cpoj.v3i1.33768 34.lelas jl, merriman gj, riley po, kerrigan dc. predicting peak kinematic and kinetic parameters from gait speed. gait posture. 2003; 17(2):106-12. doi:10.1016/s0966-6362(02)00060-7 https://doi.org/10.33137/cpoj.v8i1.44416 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 2 2024 review article williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i2.43716 1 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 review article wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers williams-reid h1, johannesson a2, buis a1* 1 department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. 2 össur clinics emea, stockholm, sweden. introduction 1: overall rationale, aims, and objectives wound healing is the biological process of tissue repair following damage,1 such as amputation surgery or prosthetic-use induced deep tissue injuries (dtis). the process comprises four interrelated stages: hemostasis, inflammation, proliferation, and tissue remodeling.2-4 it demands a high degree of cellular coordination, introducing several avenues through which impairments can occur. consequently, wound healing can be stalled (also referred to as non-healing, impaired, or chronic) not by one isolated factor, but by several smaller contributing issues.5 common post-amputation surgical site healing complications include infection, pain, hematomas, tissue necrosis, poor residual limb formation, recurrent ulceration, wound dehiscence, and stitch abscesses.6,7 persistent complications, in other words, poor healing, can necessitate revision surgeries or even re-amputation at more proximal levels.6 despite the complexity of wound healing, current healing assessments remain largely surface-level and subjective. this is especially relevant for major lower limb amputees, open access abstract background: the timely provision of load-bearing prostheses significantly reduces healthcare costs and lowers post-amputation mortality risk. however, current methods for assessing residuum health remain subjective, underscoring the need for standardized, evidence-based approaches incorporating physical biomarkers to evaluate residual limb healing and determine readiness for prosthetic rehabilitation. objective(s): this review aimed to identify predictive, diagnostic, and indicative physical biomarkers of healing of the tissues and structures found in the residual limbs of adults with amputation. methodology: a scoping review was conducted following joanna briggs institute (jbi) and prismascr guidance. searches using “biomarkers”, “wound healing”, and “amputation” were performed on may 6, 2023, on web of science, ovid medline, ovid embase, scopus, cochrane, pubmed, and cinahl databases. inclusion criteria were: 1) references to physical biomarkers and healing; 2) residuum tissue healing; 3) clear methodology with ethical approval; 4) published from 2017 onwards. articles were assessed for quality (qualsyst tool) and evidence level (jbi system), and categorized by study, wound, and model type. physical biomarkers that were repeated not just within categories, but across more than one of the study categories were reported on. findings: the search strategy identified 3,306 sources, 157 of which met the inclusion criteria. histology was the most frequently repeated physical biomarker used in 64 sources, offering crucial diagnostic insights into cellular healing processes. additional repeated indicative and predictive physical biomarkers, including ankle-brachial index, oxygenation measures, perfusion, and blood pulse and pressure measurements, were reported in 25, 19, 13, and 12 sources, respectively, providing valuable data on tissue oxygenation and vascular health. conclusion: ultimately, adopting a multifaceted approach that integrates a diverse array of physical biomarkers (accounting for physiological factors and comorbidities known to influence healing) may substantially enhance our understanding of the healing process and inform the development of effective rehabilitation strategies for individuals undergoing amputation. article info received: july 5, 2024 accepted: november 29, 2024 published: december 5, 2024 citation williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2 .43716 keywords amputation, scoping review, wound healing, surgical site healing, physical biomarkers, physical markers of healing, residuum healing, residual limb healing, wound management, early prosthetic rehabilitation please refer to the end of the article for a list of abbreviations & acronyms. * corresponding author: professor arjan buis, phd department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. e-mail: arjan.buis@strath.ac.uk orcid id: https://orcid.org/0000-0003-3947-293x journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 2, article no.3. 2024 https://doi.org/10.33137/cpoj.v7i2.43716 https://doi.org/10.33137/cpoj.v7i2.43716 https://doi.org/10.33137/cpoj.v7i2.43716 mailto:arjan.buis@strath.ac.uk https://orcid.org/0000-0003-3947-293x https://jps.library.utoronto.ca/index.php/cpoj/index 2 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 who typically receive a customized prosthetic limb within 3 to 20 weeks post-surgery, depending on wound healing.8,9 prosthetic fitting significantly improves mobility, physical health, and quality of life,9-11 yet determining residual limb readiness remains subjective and inconsistent.12 clinical judgment, based on superficial wound assessments, varies widely, and there are no standardized guidelines for evaluating readiness.12-14 factors such as wound healing, pain management, and limb volume are considered, but specific measurable indicators are lacking. recent studies highlight debates around key clinical decisions, such as whether to use rigid or soft dressings in the immediate post-operative stage to promote healing.15,16 moreover, individuals awaiting amputation frequently present with multiple comorbidities that complicate the healing process. a leading cause of amputation is diabetesrelated complications,17 yet hyperglycemia can lead to vascular stiffening, microvascular dysfunction, reduced tissue oxygenation, and, consequently, impaired wound healing.18 this variability in clinical practices underscores the need for more objective measures, such as biomarkers, to assess wound healing and readiness for prosthetic use. biomarkers, defined by the u.s. fda (food & drug administration) as measurable indicators of biological processes or responses to treatment,19 offer a way to reduce the subjectivity inherent in current practices. however, there is limited research on using biomarkers to monitor healing and support early prosthetic rehabilitation post-amputation. existing studies, like those investigating tissue composition changes during prosthetic use,20 focus on mature residual limbs, while early-stage limbs face higher risks of issues like ulceration and volume fluctuation, complicating socket fit.21 exploring these early stages is crucial for successful prosthetic rehabilitation and preventing further surgeries. to meet this research need, a scoping review was developed and implemented with the following aim: identify predictive, diagnostic, and/or indicative biomarkers (physical, chemical, or other) of healing of the tissues and structures found in the residual limbs of adults with amputation. to meet this aim, the following objectives were compiled: 1) collate and synthesize the reported definitions of healing and non-healing in the literature investigating healing of the tissues and structures found in the residual limbs of adults with amputation. 2) identify and collate physical biomarkers predictive, diagnostic, and/or indicative of healing repeated in sources investigating healing of the tissues and structures found in the residual limbs of adults with amputation. 3) identify and collate chemical biomarkers predictive, diagnostic, and/or indicative of healing repeated in sources investigating healing of the tissues and structures found in the residual limbs of adults with amputation. 4) assess the quality and levels of evidence of sources investigating healing of the tissues and structures found in the residual limbs of adults with amputation. the term "physical" refers to biomarkers like wound ph, temperature, or collagen levels detected through histochemical staining,22 while "chemical" pertains to markers present in wound tissue, fluids, serum/blood, sebum, saliva, or sweat, such as cytokines or matrix metalloproteinases. indicative biomarkers suggest the presence of a condition or physiological state but are not definitive. predictive biomarkers provide prognostic information, indicating the likelihood of developing a condition or predicting a patient's response to treatment. diagnostic biomarkers confirm the presence of a specific disease or condition, or in this context, definitively identify the progression of healing. 2: part 2 rationale, aims, and objectives this article (part 2) addresses objective 2 and constitutes the second instalment in a series of three articles, each of which sequentially examines objectives 1 to 3. as concluded in part 1,23 there exists a significant lack of consensus and standardization in defining healing and nonhealing within the literature that investigates the healing of the tissues and structures found in the residual limbs of adults with amputations. most approaches fail to consider deeper tissue healing and the mechanical properties of the tissue essential for functionality, particularly in the context of prosthetic use.23 to address this, part 1 outlined steps for developing a tailored and relevant scale that incorporates biomarkers for assessing wound healing in the context of residual limbs post-amputation. physical biomarkers assess the macro-level physiological properties of a biological system, such as heart rate, which indicates cardiac functionality. these biomarkers are typically measured in real-time or continuously, offering the potential for ongoing monitoring of wound healing. for instance, recent work by patel et al.24 synthesized research on wearable electronics for skin wound monitoring and healing, noting the development of sensors capable of realtime monitoring of physical biomarkers, including ph, temperature, moisture, and oxygen. day et al.12 similarly concluded that future research should assess transcutaneous oxygen perfusion, along with other noninvasive measures of blood flow and perfusion, as a more objective means of tracking the progression of healing over time. notably, transcutaneous oxygen pressure (tcpo2) was the only objective measure employed among the 15 sources reviewed in their study.12 previous research has indicated that a tcpo2 value below 40 mmhg is associated https://doi.org/10.33137/cpoj.v7i2.43716 3 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 with a 24% increased risk of healing complications in lower limb amputations compared to values above 40 mmhg.25 physical biomarkers are already widely utilized in various healthcare settings for different applications. for example, peripheral oxygen saturation (spo2) has been employed by the uk national health service (nhs) to detect early deterioration in patients with covid-19 in primary and community care settings.26 medically certified pulse oximetry fingertip devices were distributed to patients, enabling the rapid real-time measurement of oxygen saturation levels without the need for blood samples.26 furthermore, spo2 has also been shown to correlate with wound healing; park et al.27 demonstrated that, during the early stages of wound healing, oxygen saturation can drop to a maximum of 85%, indicating a hypoxic wound environment. as healing progresses, oxygen saturation typically increases and is maintained within the normal range of 95% to 100% by the end of the healing process, as observed in a rat cutaneous wound model.27 these existing pulse oximetry systems demonstrate significant potential for adaptation and reapplication in the monitoring of residual limb healing and early prosthetic rehabilitation. this serves as a clear example of how the requirement to identify and develop techniques for quantifying biomarkers within the proposed healing assessment scale can be effectively addressed. in conclusion, physical biomarkers represent promising objective measures for inclusion in the development of an assessment scale of residual limb healing post-amputation. therefore, the aim of this review was to: identify predictive, diagnostic, and/or indicative physical biomarkers of healing in the tissues and structures found in the residual limbs of adults with amputations. to achieve this aim, the following objectives have been established: 1) identify and compile physical biomarkers that are predictive, diagnostic, and/or indicative of healing as reported in sources investigating the tissues and structures of residual limbs in adults with amputations. 2) identify and summarize the techniques used to quantify these physical biomarkers in studies focused on the healing of tissues and structures in residual limbs of adults with amputations. 3) assess the quality and levels of evidence in sources investigating the healing of tissues and structures found in the residual limbs of adults with amputations. methodology given the novelty of the research question and the broad array of sources available on biomarkers, a scoping review was deemed the most appropriate approach to address the research question. the complete review methodology has been previously detailed in part 1.23 in brief, the review adhered to the preferred reporting items for systematic reviews extension for scoping reviews (prisma-scr) checklist and guidance28,29 and followed the joanna briggs institute (jbi) guidelines.30-33 data management was conducted using excel version 2303 (microsoft, washington, usa) operating on windows 11 version 22h2 (microsoft, washington, usa). 1: inclusion criteria and search strategy the first screening phase, focusing on titles and abstracts, applied primary inclusion criteria including references to biomarkers of wound healing, healing of tissues found in the residual limb, and publications from 2017 onwards. due to the limited research specifically addressing biomarkers for residual limb healing, the inclusion criteria were expanded to encompass literature on biomarkers of healing, requiring that participants have a clearly defined wound in tissues and structures comparable to those of an amputation residuum. in the second phase of full-text screening, additional criteria were introduced, including clear and reproducible methodologies, ethical approval (where applicable), and the involvement of human participants (aged 18+) or murine models. to ensure a comprehensive review, sources were considered from diverse contexts, such as home, hospital community, and academic institutions, and across multiple disciplines, including healthcare professionals and engineers. additionally, to mitigate bias towards highincome countries and western publication bias,34,35 studies from any geographical region were included, provided they were available in the english language due to the primary reviewer’s language limitations. an exhaustive list of terms derived from the research question was generated and the search strategy was piloted. finalized search terms, based on terms “biomarker”, “amputation”, and “wound healing”, were then applied to several databases, including web of science, medline (hosted on the ovid platform), embase (hosted on the ovid platform), scopus, cochrane, pubmed, and cinhahl. the extensive number of sources generated during the initial searches prompted a reassessment of the inclusion criteria. additionally, the rapid advancements in wound healing biomarkers36 underscored the necessity for more recent data. a recent scoping review examined prognostic factors (biomarkers) associated with ulcer healing, a common diabetic complication that can precede amputation,37 specifically focused on sources published before 2017.38 in light of this context, it was decided to include only sources published in or after 2017, thereby ensuring the relevance and timeliness of the reviewed literature. search results were exported and managed in endnote 20 (version 20.2.1, clarivate, 2021), where duplicates were removed. https://doi.org/10.33137/cpoj.v7i2.43716 4 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 2: data extraction, analysis, and presentation data extraction (including study type and characteristics, and physical biomarkers) was performed by the primary reviewer using a pre-defined tool for sources that passed both screening rounds. the qualsyst tool39 (chosen for its quantitative and reproducible quality assessment) and the jbi levels of evidence40 were used to evaluate study quality and evidence levels respectively. a prevalence of poorquality or low-level evidence would indicate the need for methodological improvements in biomarker research. all extracted data, including references for included sources, are openly accessible in the review’s dataset.41 due to the nature of a scoping review, a meta-analysis is not considered appropriate.30 instead, basic descriptive analyses, such as frequency counts of key concepts, were prioritized. extracted biomarkers were subject to frequency counts, and evidence levels and quality scores were compiled. the included sources are categorized based on study type (randomized controlled trial, case study, observational study, or bench research), wound type (diabetic, amputation, or other), and model type (human, murine, or other, such as cell lines). each category provides distinct insights into wound healing, contributing to a comprehensive understanding from multiple perspectives. physical biomarkers that were observed repeatedly, not only within categories but also across multiple study categories, are visually represented in a tree-map graph and are further analyzed in the discussion through comparison with existing literature. this manuscript focuses on these recurring biomarkers, based on the assumption that repetition indicates a stronger evidence base for the biomarker’s use, thus supporting further research on these biomarkers. a separate descriptive section summarizes the methodologies for biomarker quantification. results 1: overall results 1.1: search strategy results as detailed in part 1,23 the search strategy implemented in may 2023 resulted in the identification of 7,041 sources. following the removal of 3,735 duplicate records, a total of 3,306 titles and abstracts were screened (see part 1 for the primsa diagram23). ultimately, 219 articles were selected for data extraction. exclusions were based on factors such as review articles study type, unclear methodologies, and lack of ethical approval. of the 219 articles selected, 157 reported on physical biomarkers, and were therefore the focus of this part 2 review. table 1: overview of the study types of all 157 included sources utilizing physical biomarkers. the table categorizes the included sources by study type, wound type, and model type and provides the reference number for the category used throughout the review. the number of included sources and percentage of the 157 included sources in each category are detailed. study type category reference number number (%) of included sources included source references randomised controlled trial 1 7 (4%) 42, 135, 156, 172, 193, 194, 196 case-controlled study 2 3 (2%) 149, 151, 162 observational prospective diabetic wounds 3 14 (9%) 45, 54, 138, 140, 141, 143, 153, 173, 176, 178, 182, 188, 191, 192 amputation 4 5 (3%) 44, 137, 139, 179, 198 other wounds 5 9 (6%) 46-48, 144, 146, 152, 161, 164, 181 retrospective diabetic wounds 6 13 (8%) 43, 70, 113, 130, 133, 134, 147, 148, 160, 163, 165, 168, 175 amputation 7 14 (9%) 128, 132, 142, 145, 166, 169, 177, 180, 183-185, 187, 189, 195 other wounds 8 13 (8%) 136, 150, 154, 155, 157-159, 167, 170, 171, 174, 186, 190 bench research diabetic wounds rat models 9 22 (14%) 50, 59, 68, 71, 80, 81, 83, 86, 89, 91, 94, 97, 98, 100, 106, 108, 111, 112, 114, 116, 119, 123 mouse models 10 36 (23%) 49, 52, 53, 57, 60, 61, 63-65, 69, 72, 73, 77-79, 82, 85, 87, 88, 90, 93, 95, 102, 103, 109, 110, 115, 117, 121, 122, 124-126, 129, 131, 197 other models 11 5 (3%) 58, 62, 74, 75, 96 other wounds rat/mouse models 12 13 (8%) 51, 55, 56, 66, 67, 76, 84, 92, 99, 101, 104, 105, 118 other models 13 3 (2%) 107, 120, 127 https://doi.org/10.33137/cpoj.v7i2.43716 5 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 1.2: quality and levels of evidence for a detailed reporting and discussion of the quality and levels of evidence of all 219 sources that meet the inclusion criteria for the overall review aim, please refer to part 1.23 the levels of evidence across the 157 included sources were variable encompassing both the highest and lowest tiers of evidence. for instance, within the effectiveness category, only 1 study42 (of 157 included sources) was graded as 1.b, and 6 studies43-48 received a grade of 1.c; however, a significant majority, 79 sources49-127 were rated at 5.c (the lowest level of evidence). all studies evaluated were quantitative, with none receiving a limited quality score. specifically, 79% of all studies were demonstrated strong quality,43,44,46,47,49-52,54,55,57-63,67-71,74,7681,91-99,101-108,111,115,117,118,121-187 19% were rated as good quality,42,45,53,56,64-66,72,73,89,90,100,109,110,112-114,116,119,188-197 and only 4% were classified as adequate quality.48,75,120,198 1.3: study types and characteristics of the 157 included sources, 79 were classified as bench research studies (table 1study categories 9 to 13), while only 3 were identified as case-controlled studies.149,151,162 this data was further analyzed based on wound type and model type (table 1). notably, bench research studies focusing on diabetic wounds using mouse models constituted the largest study category, comprising 36 sources. in categories 1 to 8 (table 1), human participants were employed, with sample sizes ranging from a minimum of 2 (a case-controlled study151) to 7,187 (an observational retrospective study145). within the human participant studies that provided gender information (71 of 78 sources) sample genders ranged from a minimum of 20% male161 to 99% male145 (table 2). medians of the mean ages were all above 60 years, with means ranging from 27.1146 years to 77.3 years.195 in some sources, age was instead described by ranges and median ages (table 2). 34 (44%) of the 78 human participant studies investigated diabetic wounds, 21 (27%) focused on amputations (some of which were a result of a diabetic wound), and 23 (29%) investigated other wounds (table 2). examples of other wounds included acute lower extremity wounds,196 anterior cruciate ligament tear reconstruction,199 chronic foot ulcers,47,190 and appendectomy surgical sites.167 the synthesis of the 79 bench research studies (study categories 9 to 13) revealed complex sample characteristics. among the 71 studies employing rat or mouse models, 46 (65%) used exclusively male rodents, 7 (10%) used only females, and the remainder either did not specify gender or used both. seven of the eight studies in “other models” (categories 11 and 13) utilized cell lines (animal and human), wound healing assays (scratch assays), and/or human tissue samples.58,74,75,96,107,120,127 the remaining study employed a mathematical model.62 of the 79 bench research studies, 63 (80%) focused on diabetic wounds (table 1study categories 9 to 11), with only one study92 examining hind limb amputation in spraguedawley rats. the remaining 15 studies investigated other wounds, including sciatic nerve injuries (cut and crush injuries; 2 sources67,84), traumatic injuries (musculoskeletal trauma and blast-associated injuries; 3 sources55,104,105), skin wounds (7 sources51,56,66,76,99,101,118), and general wound cell models (includes wound/scratch assays; 3 sources107,120,127). 2: repeated physical biomarkers the most frequently reported physical biomarker was histology, which encompasses measures such as collagen deposition and the degree of angiogenesis, all determined through microscopic analysis of sectioned and stained tissue samples. histology was employed in 64 sources representing 41% of the 157 included sources (table 3 and figure 1). additional physical biomarkers, utilized not only within but also across various source types, included anklebrachial index (abi), oxygenation measures (such as tcpo₂ [transcutaneous partial oxygen pressure], spo₂ [peripheral oxygen saturation], and sto₂ [tissue oxygen saturation]), perfusion, and blood pressure and pulse measurements. these biomarkers were reported in 25 (11%), 19 (9%), 13 (6%), and 12 (5%) sources, respectively (table 3). 3: measurement techniques of repeated physical biomarkers to quantify the repeated physical biomarkers, measurement techniques including pulse oximeters, immunostaining, and blood pressure cuffs were utilized (table 4). interestingly, both abi and perfusion require a doppler ultrasound to be quantified. estimated glomerular filtration rate (egfr) was generated from serum creatinine levels (a routine blood marker) and was therefore calculated from routine blood test results. discussion 1: key findings this review identifies predictive, diagnostic, and/or indicative physical biomarkers of residual limb healing in adults with amputation, providing the foundation for the development of a standardized assessment scale for monitoring healing progression and prosthetic rehabilitation post-amputation. histological analysis, the most frequently reported biomarker, diagnoses cellular healing progression by quantifying key components such as collagen and keratinocyte presence which are crucial for all four wound healing phases. however, its need for wound tissue samples raises ethical and practical concerns, limiting its clinical application. non-invasive hemodynamic and oxygenation biomarkers, such as transcutaneous oximetry, oxygen saturation measures, abi, and skin perfusion https://doi.org/10.33137/cpoj.v7i2.43716 6 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 pressure (spp), provide valuable information regarding tissue oxygenation and vascular health, both of which predict and indicate healing outcomes. while egfr serves as an indirect marker of kidney function that influences the healing process, it does not directly reflect the underlying mechanisms of healing. it identifies a comorbidity that may predict impaired healing, thus rendering it less useful for post-amputation assessments but valuable for preamputation risk assessment. to enhance monitoring capabilities, there is a need for improved biomarker quantification techniques, such as the development of wearable sensors, as well as the utilization of multiple objective biomarkers to address the complex health considerations (comorbidities and heterogeneity) of individuals with amputation. there is a need for future research to determine biomarker threshold values for predicting, diagnosing, and indicating healing, ensuring their safe and effective application in the amputee population. 2: repeated physical biomarkers 2.1: physical biomarkers histological analysis, utilizing techniques such as tissue sectioning, staining, and microscopic examination, provides cellular-level visual evidence of healing.200 techniques like masson’s trichrome staining quantify collagen content,201 a crucial regulator in all wound healing phases.202 during the hemostasis phase, collagen promotes platelet activation and fibrin clot formation at the injury site. in the inflammatory phase, the activation of immune cells leads to the release of pro-inflammatory cytokines, which encourage fibroblast migration and collagen deposition.202 during proliferation, collagen degradation stimulates the production of growth factors and fibroblast proliferation, driving angiogenesis and re-epithelialization.202 finally, during maturation, collagen composition alterations are essential for tissue remodeling and the tensile strength of healed skin. bibi et al.52 utilized histological analysis to show that lapachol-treated mice with full-thickness wounds exhibited increased, organized collagen deposition and significant wound size reduction by days 8 and 10 post-wounding compared to controls (p < 0.001). hematoxylin and eosin (h&e) staining serves to assess keratinocyte presence.203 keratinocytes migrate into the wound to repair epidermal defects, and their proliferation, regulated by cytokines and growth factors, ensures complete wound coverage.204 ferroni et al.172 employed h&e staining to assess diabetic foot ulcers (dfus) treated with therapeutic magnetic resonance (tmr®). dfus treated with a non-functioning tmr® device exhibited a limited presence of fibroblasts, endothelial cells, keratinocytes, and collagen fibers (p < 0.001), which correlated with significantly longer healing times.172 the dfus treated with an active tmr® device healed faster, averaging 44.8 ± 12.1 days versus 96.7 ± 23.5 days in the sham group (p < 0.05).172 thus, histological analysis serves as a critical diagnostic tool for quantifying healing progression, particularly through the measurement of angiogenesis and collagen deposition at the wound site. estimated glomerular filtration rate (egfr) is a quantitative measure derived from serum creatinine or cystatin c test results, serving as an indicator of kidney function by assessing the volume of blood filtered by the kidneys per minute.205 its primary application is within observational studies concerning diabetic wounds, likely a consequence of the detrimental effects of diabetes on renal function.206 chronic kidney disease (ckd) is characterized by a sustained reduction in egfr to values below 60 ml/min/1.73 m² for a duration of three months or longer.207 the impact of ckd on wound healing is well-documented; findings from murine excisional wound models indicate that ckd-affected mice present altered blood chemistry and hematology profiles, reduced rates of re-epithelialization and granulation tissue deposition, and differential expression of genes associated with wound healing, including vascular endothelial growth factor, interleukin-1 beta, endothelial nitric oxide synthase, and inducible nitric oxide synthase.208 these changes are accompanied by significant reductions in cellular proliferation and angiogenesis, alongside heightened inflammatory responses when compared to control groups.208 therefore, egfr serves as an indicator of a comorbidity predictive of non-healing, making it less useful for post-amputation assessments but valuable for pre-amputation evaluations to identify patients at higher risk of impaired healing. cell viability is used only in bench research studies employing scratch assays, where healing is assessed by observing the migration of cells across a created “scratch” in the assay. in such studies, it is necessary to ensure the health of the cells to validate that the observed migration (or lack thereof) is a result of healing mechanisms, rather than poor cell culture conditions. cell viability tests confirm this by quantifying the number of live/dead cells and/or the metabolic activity of the cells. kasowanjete et al.74 for example, used trypan blue stain to determine the number of viable cells in a cellular wound model investigating the impact of photobiomodulation at 660 nm on in vitro diabetic wound healing. dead cells take up the dye due to permeable cell membranes, whereas the impermeable membranes of viable cells prevent them from taking up the dye. cell viability is therefore diagnostic of cell health, and indicative of healing, but offers little clinical applicability to the amputee population. instead, it is limited to use in preclinical research to evaluate the efficacy of novel therapeutic compounds designed to promote healing, or better understand the cellular level mechanisms that control healing in residual limb tissue. https://doi.org/10.33137/cpoj.v7i2.43716 7 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 table 2: the characteristics of the included sources involving human participants, specifically wound type, sample size, sample gender, and sample age, are detailed for study categories 1 to 8 (refer to table 1). the notation "no. (%) of references" indicates the number and percentage of sources that provide characteristic information relative to the total number of sources within that category (t.g. = treatment groups; c.g. = control groups; no. = number). study category 1 2 3 4 5 6 7 8 wound type totals diabetic 5 (42, 135, 172, 193, 194) 2 (149, 151) 14 (45, 54, 138, 140, 141, 143, 153, 173, 176, 178, 182, 188, 191, 192) 0 0 13 (43, 70, 113, 130, 133, 134, 147, 148, 160, 163, 165, 168, 175) 0 0 amputation 1 (156) 1 (162) 0 5 (44, 137, 139, 179, 198) 0 0 14 (128, 132, 142, 145, 166, 169, 177, 180, 183185, 187, 189, 195) 0 other 1 (196) 0 0 0 9 (46-48, 144, 146, 152, 161, 164, 181) 0 0 13 (136, 150, 154, 155, 157159, 167, 170, 171, 174, 186, 190) sample size totals range (minmax) 16-50 2-58 10-684 10-556 5-735 92-1032 13-7187 45-637 median 33 20 66 19 60 232 121 120 no. (%) of references 7 (100%) 3 (100%) 14 (100%) 5 (100%) 9 (100%) 13 (100%) 14 (100%) 13 (100%) sample gender (% male) totals range (minmax) 40%-82% 47%-100% 35%-84% 60%-73% 20%-90% 45%-83% 29%-99% 54%-78% median 61% 50% 67% 64% 63% 62% 71% 66% no. (%) of references 5 (71%) (42, 135, 156, 193, 196) 3 (100%) 13 (93%) (45, 54, 138, 140, 141, 143, 153, 176, 178, 182, 188, 191, 192) 5 (100%) 8 (89%) (46, 47, 144, 146, 152, 161, 164, 181) 11 (85%) (43, 70, 113, 130, 133, 134, 160, 163, 165, 168, 175) 14 (100%) 12 (92%) (136, 150, 154, 155, 157-159, 167, 170, 171, 174, 186) sample mean age (years) totals range (minmax) t.g.: 55.0-69.0; c.g.: 52.1-64.7 60.2-61.5 48.0-67.0 49.0-74.0 27.1-72.6 54.5-72.5 61.5-77.3 56.0-74.9 median t.g: 64.2; c.g.: 62.0 60.9 61.2 68.4 65 61.2 66.5 72 no. (%) of references 6 (86%) (42, 135, 156, 172, 193, 196) 2 (67%) (151, 162) 13 (93%) (45, 54, 138, 140, 141, 143, 153, 173, 176, 178, 182, 188, 192) 4 (80%) (44, 137, 139, 198) 6 (67%) (46, 47, 144, 146, 152, 181) 12 (92%) (43, 70, 113, 130, 134, 147, 148, 160, 163, 165, 168, 175) 12 (86%) (128, 132, 142, 145, 166, 177, 180, 183, 184, 187, 189, 195) 9 (69%) (136, 155, 157-159, 170, 171, 174, 186) sample age range (years) totals range (minmax) na 45-65 20-89 23-66 28-81 17-96 26-96 na no. (%) of references na 1 (33%) (149) 6 (43%) (45, 143, 173, 176, 182, 191) 2 (40%) (44, 179) 3 (33%) (161, 164, 181) 5 (38%) (147, 148, 163, 165, 175) 4 (29%) (177, 180, 187, 189) na sample median age (years) totals range (minmax) na na na na na 72.5 47.0-62.0 31.0-71.2 median na na na na na 72.5 54.5 68.4 no. (%) of references na na na na na 1 (8%) (133) 2 (14%) (169, 185) 3 (23%) (150, 154, 167) https://doi.org/10.33137/cpoj.v7i2.43716 8 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 table 3: a comprehensive breakdown of the repeated physical biomarkers. a biomarker was considered “repeated” if it was used in more than one source within a study category and appeared in more than one study category. the occurrence of these biomarkers in the 157 included sources is presented, along with their representation across the various study categories (see table 1; abi = ankle-brachial index; tcpo2 = transcutaneous oxygen pressure; spo2 = saturation of peripheral oxygen; sto2 = skeletal muscle oxygen saturation; spp = skin perfusion pressure; sbp = systolic blood pressure; dbp = diastolic blood pressure; egfr = estimated glomerular filtration rate). repeated physical biomarkers sources study categories frequency % of included sources references frequency % of categories categories included histology 64 41% 50-53, 56, 57, 59-61, 63-68, 71-73, 7683, 85-91, 93, 95, 97-103, 106, 108112, 114-119, 121-126, 131, 172, 194, 197 4 31% 1, 9, 10, 12 abi 25 16% 113, 128, 132, 141, 143, 145, 154, 155, 157, 161, 163-166, 168, 173, 174, 176, 181, 183, 186, 188, 192, 193, 196 6 46% 1, 3, 5, 6, 7, 8 tcpo2, spo2, and sto2 19 12% 45, 48, 54, 70, 113, 132, 139, 141, 144, 147, 148, 153, 165, 168, 179-181, 188, 191 5 38% 3, 4, 5, 6, 7 perfusion (includes spp) 13 8% 42, 46, 48, 142, 155-157, 161, 164, 170, 174, 189, 196 4 31% 1, 5, 7, 8 blood pulse and pressure measures (includes sbp, dbp, toe pressure, etc.) 12 8% 113, 134, 147, 148, 160, 165, 175, 177, 187, 188, 192, 195 3 23% 3, 6, 7 egfr 5 3% 43, 133, 138, 168, 173 2 15% 3, 6 cell viability 5 3% 74, 96, 107, 120, 127 2 15% 11, 13 figure 1: treemap visualization displaying the frequencies of the repeated physical biomarkers. a biomarker was considered “repeated” if it was used in more than one source within a study category and appeared in more than one study category. the occurrence of these biomarkers in the 157 included sources is presented as a percentage (abi = ankle-brachial index; tcpo2 = transcutaneous oxygen pressure; spo2 = saturation of peripheral oxygen; sto2 = skeletal muscle oxygen saturation; spp = skin perfusion pressure; sbp = systolic blood pressure; dbp = diastolic blood pressure; egfr = estimated glomerular filtration rate). table 4: measurement techniques reported in included sources used to quantify repeated physical biomarker expression (abi = ankle-brachial index; tcpo2 = transcutaneous oxygen pressure; spo2 = saturation of peripheral oxygen; sto2 = skeletal muscle oxygen saturation; spp = skin perfusion pressure; sbp = systolic blood pressure; dbp = diastolic blood pressure; egfr = estimated glomerular filtration rate; h&e = hematoxylin and eosin; mtt = 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide). repeated physical biomarkers biomarker measurement techniques histology immunostaining of sectioned wound tissue samples using toluidine blue, masson’s trichrome stain, h&e stain, and primary antibody stains. abi vascular doppler ultrasound. tcpo2, spo2, and sto2 percutaneous oxygen partial pressure detector. perfusion (includes spp) laser doppler probe and blood pressure cuff. blood pulse and pressure measures (includes sbp, dbp, toe pressure etc.) pulse oximeter. egfr calculated from routine blood test results. cell viability mtt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay, trypan blue exclusion assay, and live/dead cell staining. treemap representation of the repeated physical biomarkers histology, 41% abi, 16% tcpo2, spo2, and sto2, 12% perfusion (includes spp), 8% blood pulse and pressure measures (includes sbp, dbp, toe, etc.), 8% egfr, 3% cell viability, 3% https://doi.org/10.33137/cpoj.v7i2.43716 9 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 transcutaneous oxygen pressure (or transcutaneous oximetry [tcpo2]), peripheral oxygen saturation (or pulse oximetry [spo2]), and skeletal muscle oxygen saturation (sto2) are non-invasive metabolic measures that provide insight into tissue oxygenation levels.209 oxygen is critical for wound healing, influencing various stages of the healing process under both hypoxic and normoxic conditions.209 during the hemostasis phase, hypoxia plays a pivotal role in initiating the wound healing process by enhancing the activity of reactive oxygen species (ros).210 in the inflammation phase, the elimination of bacteria occurs via phagocytosis, a process contingent upon high partial oxygen pressure.211 vascular endothelial growth factor, a key growth factor in angiogenesis, is upregulated by hypoxia-inducible factor 1-alpha, which is activated by both hypoxia and ros during the proliferation phase. in the maturation phase, which includes tissue remodeling, oxygen facilitates keratinocyte activity through ros.211 loo and halliwell212 utilized a keratinocyte-fibroblast co-culture model of wound healing, to demonstrate hydrogen peroxide (h2o2), a common ros, enhanced keratinocyte proliferation and accelerated the rate of epithelialization. oxygen is evidently vital for facilitating cellular activity and tissue repair during healing, however techniques for assessing oxygen levels differ. for example, tcpo2 noninvasively quantifies local tissue perfusion via electrochemical sensors,213 with calf values exceeding 40 mmhg associated with a higher percentage of successful healing after below-the-knee amputation.214 similarly, a retrospective study found a statistically significant relationship (p < 0.001) between lower tcpo2 values and prolonged wound healing duration in 84 patients with critical limb-threatening ischemia.132 contrastingly, sto2 is assessed non-invasively through measurements of oxyhemoglobin and deoxyhemoglobin using near-infrared spectroscopy.215 lee et al.216 demonstrated that skin wounded by pressure injuries exhibited a significantly higher median sto2 compared to healthy and scabbed skin. thus, oxygenation measures function as predictive and indicative markers of healing post-amputation. they may also predict risk of further wounds to the residuum like deep tissue injury (dti), caused by reduced oxygen levels resulting from vascular occlusions induced by loading during lower limb prosthetic use.217 the hemodynamic biomarkers, ankle-brachial index (abi), perfusion, and blood pulse and pressure measures, indicate the vascular status surrounding a wound. insufficient perfusion, characterized by poor macro-circulation, increases progressive hypoxia risk and diminishes nutrient and survival factors delivery necessary for tissue repair.218 this impairs processes such as angiogenesis, collagen deposition, and epithelialization, resulting in sustained inflammation. the angiogenesis phase of wound healing involves the formation of new blood vessels that supply nutrients, immune cells, and oxygen to the wound site.219 it is characterized by an initial period of rapid and excessive capillary growth that eventually regresses to a vascular density akin to that of normal skin.219 therefore, hemodynamic measures are predictive and indicative of healing. for example, a systematic review indicated that an abi value of less than 0.5 in patients with dfus, calculated as the ratio of blood pressure in an ankle artery to that in an arm artery, was significantly associated with an increased incidence of major amputation.220 skin perfusion pressure (spp) of ≥ 40 mmhg and toe pressure of ≥ 30 mmhg (or ≥ 45 mmhg) were also linked to at least a 25% higher likelihood of healing. similarly, a study of 81 diabetic patients concluded that normal abi (0.90-1.30) correlated with successful healing (p < 0.05), while abi (≤ 0.40) was associated with failed transmetatarsal amputation (p < 0.01).183 while valuable, hemodynamic measure interpretations vary. for instance, spp evaluates vascularity by assessing the blood pressure required to restore microcirculatory or capillary flow after controlled occlusion, while abi reflects the ratio of the ankle to arm blood pressure. the contrasting literature regarding each biomarker must be addressed. for example, calf tcpo2 values above 40 mmhg are associated with improved healing outcomes after below-the-knee amputation, while values below 20 mmhg correlate with poorer healing.214 however, a 2012 meta-analysis found insufficient evidence to establish an optimal tcpo2 threshold value for lower limb amputation clinical use.25, 214 this review identifies the physical biomarkers commonly used in wound healing literature but highlights the need for further research to determine their threshold values, safety, and applicability in the amputee population. 2.2: quantification techniques the application of physical biomarkers in the proposed residual limb healing assessment scale is influenced by the methods used to quantify these biomarkers. histological analysis offers the most detailed and diagnostic view of wound healing progression, but its quantification technique presents significant challenges. the requirement for wound tissue collection restricts histology’s use primarily to bench research in animal models, as ethical concerns limit the use of human tissue samples.221 for example, in animal studies, such as that of bibi et al.,52 tissue samples were collected at defined intervals (days 3, 7, and 10 post-wounding), allowing discrete snapshots of healing progression. conversely, hemodynamic and oxygenation measures were predominantly utilized in human participant studies, likely due to their non-invasive measurement techniques,222 ease of use, and incorporation into established clinical practice, such as abi for peripheral arterial disease (pad) assessment.223 their non-invasive measurement techniques are however not immune to limitations. for example, abi measurements require pressure to be applied to the limb, which can be painful in patients with ischemia or https://doi.org/10.33137/cpoj.v7i2.43716 10 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 wounds,222 both of which are associated with amputation.224,225 tcpo2 measurements require the use of heated electrodes to enhance vasodilation,214 which may pose a risk of damaging sensitive post-operative residual limbs. pulse oximetry is limited by poor peripheral perfusion, motion artefacts, and variations in skin pigmentation.226 these limitations introduce the need for improved biomarker quantification techniques specifically suited for residual limb monitoring, such as wearable wound healing sensors. for instance, ochoa et al.227 are developing an integrated smart wound dressing capable of sensing and delivering oxygen to the wound. alternatively, employing a combination of biomarkers could provide a more comprehensive view of residual limb healing. biomarkers are typically not exclusive to healing. for example, patients with lower extremity pad, a common comorbidity among amputees,228 often present with tcpo2 calf values below 40 mmhg, while values above this threshold are generally associated with successful residual limb healing after below-the-knee amputation.214 to account for the comorbidities prevalent in the amputee population, multiple biomarkers should be utilized to provide a holistic view of residual limb health. 3: overall search results and study characteristics most reviewed sources focused on diabetic wounds, a reflection of the global burden of diabetes, with an estimated 529 million individuals living with diabetes worldwide in 2021.229 dfus are the most common complication of diabetes230 and a significant risk factor for amputation.231,232 for example, the scottish physiotherapy amputee research group (sparg) “survey of the lower limb amputee population in scotland 2019 public report” noted that over half (56%) of all lower limb amputees had the etiology of diabetes.233 pre-amputation assessment is especially critical for patients with a greater number of comorbidities, such as diabetes, and suboptimal physiological factors known to predict wound complications.12 diabetes can impair wound healing via hyperglycemia-induced vascular stiffening, microvascular dysfunction, and reduced oxygenation.18 therefore, physical biomarkers may enhance pre-amputation assessments to improve post-amputation outcomes. age is another key factor affecting healing, with medians of the mean participant ages in included human studies ranging from 60.9 to 70.0 years, highlighting a predominance of older adults. most non-healing wounds are a result of vascular disease,234 venous insufficiency,235 areas of high unrelieved pressure,236 diabetes,237 and disability;238 conditions that are increasingly prevalent as the population ages. for instance, public health england reports diabetes prevalence rising from 9.0% among individuals aged 45 to 54 years to 23.8% among those aged 75 years and over.237 age-related factors, such as prolonged inflammation and increased production of reactive oxygen species during healing, can lead to chronic wounds.239 this aging effect is also reflected in the sparg 2019 report, which found the median age at the time of lower limb amputation to be 67 years.233 as aging exacerbates healing complications and delays recovery, there is a critical need for objective measures of wound healing to accelerate prosthetic fitting and improve outcomes. gender also plays a significant role in predicting wound complications. an analysis of gender characteristics across human participant studies revealed that the median proportion of male participants ranged from 50% to 71%. male gender is a risk factor for dfu development,240 poorer dfu healing,241 increased post-surgical infection rates,242 and higher in-hospital immortality rates after trauma.243 in the sparg 2019 report, 71.5% of lower limb amputees were male,233 though studies also indicate that women may be less likely to successfully receive a lower limb prosthesis after amputation.244 these disparities highlight the need for gender-specific research245 and biomarkers not influenced by hormonal or gender-related factors. most studies did not investigate wound healing after amputation but focused on wounds in patient populations similar to those who undergo amputation, highlighting the lack of standardized approaches and understanding of the tissue changes that occur in residual limbs post-amputation. by extrapolating findings from wound healing studies in tissues and structures found in residual limbs, a foundational database of potential biomarkers can be established for use in residual limb healing. notably, all studies on amputation included in this review examined lower limbs, which account for 4-5 times more amputations than upper limbs246 and face unique residual limb health requirements due to weight-bearing requirements during ambulation. 4: methodological discussion 4.1: methodological strengths a broad exploration of the literature on biomarkers related to healing is provided in this review, allowing for the inclusion of diverse sources without strict criteria, unlike a systematic review which requires a focused research question. instead, the findings can serve as a basis for subsequent systematic review, such as johnson et al.’s review of il-6 in wound healing,247 particularly if high-quality evidence on a specific biomarker emerges. a notable strength of this review lies in its emphasis on the potential impact of biomarkers on the future of postamputation healing and rehabilitation. by identifying physical biomarkers capable of diagnosing, identifying, or predicting healing, a starting point for further research into https://doi.org/10.33137/cpoj.v7i2.43716 11 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 objective healing measures and quantification methodologies is provided. this moves us closer to a specific post-amputation residuum healing assessment scale, which may enable more timely healing interventions, enhancing non-healing prevention and treatment strategies.248 4.2: methodological limitations in this section limitations associated with specific study types, not explored in the part 1 review,23 are discussed. animal studies, despite genetic similarities to humans, often lack reliability due to biological differences and methodological issues,249 while mathematical models, although based on empirical data, can oversimplify the complexities of human biological processes.250-252 consequently, biomarker behavior observed in both should be interpreted cautiously, serving as potential indicators rather than definitive predictors of human responses. all wound types affecting tissues relevant to the residuum were considered appropriate for inclusion in this review, however, future research needs to account for the differences between secondary intention healing wounds, like dfus, and primary intention wounds, such as sutured surgical sites, when applying findings to clinical contexts. the synthesis of data from diverse sources in scoping reviews risks oversimplification or loss of critical detail. biomarkers that appeared repeatedly within and across different study types were prioritized for discussion in this review. however, this approach excludes biomarkers in only a single study or specific category. for example, alfawaz et al.184 investigated tibial vessel run-off (vro) and popliteal artery patency, reporting that higher vro was associated with improved healing rates and shorter time to healing following below-knee amputation, and that preoperative popliteal patency was linked to higher postoperative ambulation rates. the study's solitary use of these biomarkers led to its exclusion from broader discussions. yet, these findings suggest potential areas for future research given the statistically significant outcomes reported.184 the timing of biomarker quantification critically affects its diagnostic value; for example, hypoxia (low oxygen levels) is essential at the onset of healing, but prolonged low oxygen levels impeded healing.253 future research should address the form of the biomarkers, the timing of their measurement, and the anatomical locations from which they are sampled to improve their relevance in clinic. 5: ethical considerations in this review, evidence level was not utilized as an exclusion criterion, recognizing that recognizing that randomized controlled trials are the highest standard of evidence but are limited by high costs, restricted funding, and potential industry bias favoring positive results.254 instead, the review focused on ensuring that all included studies clearly stated ethical approval and obtained informed consent from human participants, prioritizing ethical standards over rigid adherence to evidence hierarchies. adulthood was defined as aged 18 years or older, acknowledging that global variations in defining adulthood exist (16 to 21 years),255 to prevent misinterpretation in international dissemination. despite efforts to include grey literature in this review to broaden the scope and minimize bias,256 none of the sources identified met the inclusion criteria, primarily due to insufficient methodological transparency and the absence of explicit ethical approval. conclusion this scoping review aimed to identify predictive, diagnostic, and/or indicative physical biomarkers of healing within the tissues and structures of residual limbs in adults with amputation. the integration of various physical biomarkers into the assessment of healing in residual limbs postamputation is paramount for optimizing patient outcomes. histological analysis remains the gold standard diagnostic biomarker for evaluating cellular healing processes, particularly through the measurement of collagen and keratinocyte presence, but is limited by the ethical and practical challenges of using tissue samples from human subjects. non-invasive indicative and predictive oxygenation and hemodynamic measures, such as transcutaneous oxygen pressure (tcpo₂) and anklebrachial index (abi), provide valuable insights into tissue oxygenation and vascular health; however, further research is essential to establish specific threshold values and applicability within the amputee population. while the estimated glomerular filtration rate (egfr) serves as an indirect marker of kidney function that influences the healing process, it does not directly reflect the underlying mechanisms of healing. instead, it identifies comorbidities that may predict impaired healing, rendering it less useful for post-amputation assessments compared to other physical biomarkers. nevertheless, egfr remains advantageous for pre-amputation evaluations, particularly for identifying patients at heightened risk for impaired healing. the findings underscore the global burden of diabetes, the role of age and gender disparities in wound healing, and the need for targeted research addressing these factors to improve post-amputation outcomes. most included sources focused on wounds in populations common to those undergoing amputation, rather than directly examining postamputation wound healing, highlighting a lack of understanding of the tissue changes that occur in residual limbs post-amputation. developing a holistic residual limb specific healing assessment scale that integrates a diverse array of physical biomarkers (accounting for physiological factors and comorbidities known to influence healing) could https://doi.org/10.33137/cpoj.v7i2.43716 12 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 substantially enhance our understanding of the healing process and inform the development of effective rehabilitation strategies for individuals undergoing amputation. acknowledgements the author of this article would like to express appreciation to the strathclyde body device interface mechanobiology research group for their assistance in the discussion of the review’s methodology. declaration of conflicting interests the author has no conflicts of interest to declare. authors contribution • hannelore williams-reid: the primary author of the manuscript, undertook the scoping review and prepared the final manuscript as part of a 4-year phd program. • arjan buis: the primary phd supervisor, assisted in developing the scoping review methodology and preparing the manuscript for publication. • anton johannesson: the secondary phd supervisor, assisted in developing the scoping review methodology and preparing the manuscript for publication. all authors have read and approved the final version of the manuscript. sources of support the phd project under which this scoping review/manuscript falls is funded by the ukri epsrc as part of the centre of doctoral training (cdt) in prosthetics and orthotics (p&o) (studentship 2755854 "wound management and early prosthetic rehabilitation" within project ep/s02249x/1) and by össur. references 1.herman tf, bordoni b. wound classification. wound classification [internet]. statpearls. 2024; [cited 2024, july 5]. available from: https://www.ncbi.nlm.nih.gov/books/nbk554456/ 2.wallace ha bb, zito pm. wound healing phases [internet]. statpearls. 2023; [cited 2024, july 5]. available from: https://www.ncbi.nlm.nih.gov/books/nbk470443/ 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https://assets.publishing.service.gov.uk/media/5a82c07340f0b6230269c82d/diabetesprevalencemodelbriefing.pdf https://assets.publishing.service.gov.uk/media/5a82c07340f0b6230269c82d/diabetesprevalencemodelbriefing.pdf https://www.ukri.org/news/use-of-both-sexes-to-be-default-in-laboratory-experimental-design/#:~:text=making%20both%20sexes%20the%20default&text=both%20sexes%20should%20be%20used,of%20any%20increase%20in%20costs https://www.ukri.org/news/use-of-both-sexes-to-be-default-in-laboratory-experimental-design/#:~:text=making%20both%20sexes%20the%20default&text=both%20sexes%20should%20be%20used,of%20any%20increase%20in%20costs https://www.ukri.org/news/use-of-both-sexes-to-be-default-in-laboratory-experimental-design/#:~:text=making%20both%20sexes%20the%20default&text=both%20sexes%20should%20be%20used,of%20any%20increase%20in%20costs https://www.ukri.org/news/use-of-both-sexes-to-be-default-in-laboratory-experimental-design/#:~:text=making%20both%20sexes%20the%20default&text=both%20sexes%20should%20be%20used,of%20any%20increase%20in%20costs https://www.ukri.org/news/use-of-both-sexes-to-be-default-in-laboratory-experimental-design/#:~:text=making%20both%20sexes%20the%20default&text=both%20sexes%20should%20be%20used,of%20any%20increase%20in%20costs 22 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 2 a scoping review of physical biomarkers. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.3. https://doi.org/10.33137/cpoj.v7i2.43716 canadian prosthetics & orthotics journal issn: 2561-987x wound management: physical biomarkers williams-reid et al., 2024 healing. adv wound care (new rochelle). 2014;3(5):390-9. doi:10.1089/wound.2013.0520 254.gazendam am, slawaska-eng d, nucci n, bhatt o, ghert m. the impact of industry funding on randomized controlled trials of biologic therapies. medicines (basel). 2022;9(3). doi:10.3390/medicines9030018 255.canêo lf, neirotti r. the importance of the proper definition of adulthood: what is and what is not included in a scientific publication. braz j cardiovasc surg. 2017;32(1):60. doi:10.21470/1678-9741-2016-0049 256.paez a. gray literature: an important resource in systematic reviews. j evid based med. 2017;10(3):233-40. doi:10.1111/jebm.12266 abbreviations & acronyms: abbreviations & acronyms definition abi ankle-brachial index c.g. control groups ckd chronic kidney disease dbp diastolic blood pressure dfus diabetic foot ulcers egfr estimated glomerular filtration rate u.s. fda united states food & drug administration h&e haematoxylin and eosin h2o2 hydrogen peroxide jbi joanna briggs institute mtt assay 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay nhs national health service no. number pad peripheral arterial disease prisma-scr preferred reporting items for systematic review and meta-analyses for scoping reviews ros reactive oxygen species sbp systolic blood pressure spo2 saturation of peripheral oxygen spp skin perfusion pressure sto2 skeletal muscle oxygen saturation t.g. treatment groups tcpo2 transcutaneous oximetry uk united kingdom usa united states of america vro vessel run-off https://doi.org/10.33137/cpoj.v7i2.43716 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 2 2025 research article phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i2.45759 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 research article a biofidelic mock residual limb for prosthetic socket testing phillips c1, nagpal a2, azhari f1* 1. department of mechanical and industrial engineering, university of toronto, toronto, canada. 2. division of engineering science, university of toronto, toronto, canada. introduction a prosthesis user's residual limb can fluctuate significantly in size due to factors like activity and diet.1,2 as a result, traditional rigid prosthetic sockets fail to maintain a proper coupling at the residuum-socket interface, which is essential for comfort, function, and the prevention of skin and soft tissue problems.3,4 adjustable sockets are designed to accommodate an expanding or contracting limb via straps, movable panels, or other dynamic mechanisms.5-7 to evaluate their performance, testing protocols must involve a volumefluctuating residual limb, which can either be a study participant’s limb or a lab-fabricated mock limb. clinical testing with study participants is timeand resourceintensive, requiring meaningful limb volume fluctuation and accurate measurement of that volume change within the socket. thus, apart from when subjective feedback (e.g., comfort scores) is needed, using a biofidelic mock limb— engineered to replicate both the material composition and volume fluctuations of a physiological limb—offers a more practical, cost-effective alternative. various mock limbs are used today, each designed to meet specific testing goals. rigid limbs may suit structural testing of sockets to failure, as described in recent reviews8-10 and recommended by iso 10328,11 whereas soft, compliant limbs may better replicate biomechanics at the residuumsocket interface, allowing for more precise evaluation of tissue strains12,13 and suspension effectiveness.14 most prior mock limbs for testing adjustable sockets have been static, necessitating different mock limb sizes to simulate varying volumes.6 seo et al.2 used five mock limbs of different volumes (neutral, ±3%, ±7%) to test their adjustable socket, and murdoch15 used three mock limbs to investigate socket fit across three limb volumes (neutral and ±10%). this approach limits the ability to study how the socket responds to a specific rate of limb volume change in * corresponding author: fae azhari, phd affiliation: department of mechanical and industrial engineering, university of toronto, toronto, canada. e-mail: fae.azhari@utoronto.ca orcid id: https://orcid.org/0000-0003-2559-8566 open access abstract background: evaluating prosthetic socket fit and function relies on accurately simulating load transfer between the residual limb and the socket. this limb can be either real (of a study participant) or a mock residual limb that simulates in vivo properties. mock limbs minimize reliance on resource-intensive clinical trials; however, most are static in size, limiting their use in testing clinical outcomes like socket adjustability. objective: to design and validate a biofidelic mock limb, capable of real-time, controllable volume adjustments of up to ±5% limb volume. methodology: water-filled bladders were embedded within a transtibial residual limb model made of a dual-durometer urethane composition, mimicking deep and soft tissue. an arduino-controlled syringe system was used to actuate volume adjustments. the method was validated through repeatability tests at different rates of volume change, cycling through expansion, holding at maximum volume, and contraction. volume change was quantified by measuring interfacial pressures between the limb and a static socket. findings: the limb was fabricated with readily available materials for less than cad 400. volume change rate had minimal effect on interfacial pressure throughout the testing cycle, and minimal hysteresis was found between expansion and contraction periods. repeatability was high, with a coefficient of variation of normalized pressure remaining below 10.4% over three repeated tests. conclusion: the proposed biofidelic limb was validated for its ability to mimic volume change in a transtibial residual limb. the design enables easy replication or customization to simulate different limb physiologies and anatomies. the limb allows for controllable bench-top testing during prototyping of adjustable sockets or other devices, thus bringing devices to clinical use sooner. article info received: july 18, 2025 accepted: august 21, 2025 published: september 10, 2025 citation phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v 8i2.45759 keywords prosthetic sockets; mock residual limb; adjustable sockets; biofidelic; bench-top evaluation; limb loss; artificial limbs; volume change; transtibial; rehabilitation; amputation; prosthesis. journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 2, article no. 1. 2025 https://doi.org/10.33137/cpoj.v8i2.45759 https://orcid.org/0000-0003-2559-8566 https://doi.org/10.33137/cpoj.v8i2.45759 https://doi.org/10.33137/cpoj.v8i2.45759 https://jps.library.utoronto.ca/index.php/cpoj/index 2 phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 canadian prosthetics & orthotics journal issn: 2561-987x a biofidelic mock residual limb for prosthetic socket testing phillips et al., 2025 real time. one exception to a static mock limb is a “residual limb simulator” used by paterno et al.16 to test the functionality of a flexible transfemoral prosthetic socket. the simulator utilizes a controllable syringe pump (similar to the design in this paper) to increase limb volume; however, no description of its materials, design or fabrication is provided. in this paper, the design and fabrication of a ‘biofidelic’ mock residual limb, capable of real-time, controllable volume adjustability, is presented. to validate the design, trends in interfacial pressure changes (between the limb and a rigid socket) were analyzed to assess repeatability at different rates of volume change, and the symmetry of volume change between two localized regions of the biofidelic limb was also examined. methodology design criteria and requirements to determine specific and meaningful design criteria, focus was placed on modeling a transtibial residual limb. the design choices were: region of adjustability, extent of adjustability, rate of volume adjustment, and material composition. residual limb volume changes typically occur radially (rather than axially),6 and are localized to regions with more interstitial fluid, thus away from bony prominences.17,18 a biofidelic mock limb with localized, radial volume adjustability was designed to reflect this. while the design approach allowed for bladder size and placement customization, for this study locations were selected based on literature describing pressure-tolerant areas typically actuated by panel-based adjustable sockets: the medial and lateral tibial flare regions and the posterior compartment distal to the popliteal.6,19,20 a circumferentially symmetric configuration of three adjustable regions was selected to simulate these anatomical areas and to facilitate symmetry verification during expansion and contraction. socket fit is often adjusted by adding sock plies, with over 5-ply considered clinically unacceptable,21 and 10-ply warranting a new socket.22 for a limb of 6 cm radius, a 5ply sock (1.2 mm thick) corresponds to a 4% volume increase. therefore, we targeted a ±5% volume change. volume change rates in a mature residual limb vary widely depending on factors such as activity level and diet, and have been shown to range from as slow as ±0.07%/min to ±3.3%/min after various activity programs.23 to capture this variability, testing was conducted across three orders of magnitude: from ±0.01%/min to ±10%/min. the biofidelic mock limb consists of a dual-durometer urethane bulk, surrounding a rigid centre mandrel. this composition allows for an effective force transfer from a mechanical load frame, while also offering adequate compliance at the limb-socket interface to simulate the relative movement of the limb within the socket,24 which is an important outcome measure of adjustable sockets. water-filled bladders were used to adjust volume. water was chosen over air for its incompressibility, ease of use, and similar material properties to physiological interstitial fluid or blood.17 design overview and fabrication the final design comprises three water-filled bladders embedded in a dual-durometer urethane mock limb. inspired by fabrication methods described by quinlan et al.24 for a static dual-durometer urethane limb, firstly, the inner core of the limb was casted with vytaflextm 60 (shore a hardness, smooth-on, reynolds advanced materials, chicago, il) around an aluminum mandrel (elastic modulus = 70 gpa) suspended approximately 2 cm from the mold bottom using a clamp stand during the 24-hour casting (figure 1a). next, a custom mold assembly was designed to form the bladder cavities within an outer layer of vytaflextm 20 (shore a hardness 20, smooth-on, reynolds advanced materials, chicago, il) (figure 1b and 1c). the cured inner core was suspended within the outer socket shell approximately 3 cm from the mold bottom using the clamp stand during casting of the vytaflextm 20 (24 hours). lastly, molds were removed, leaving the final dual-durometer urethane limb (figure 1d) with a volume of 1,330 ml at its fully-contracted state. all molds were 3d printed in pla, sealed to a smooth finish with a thin layer of epoxy, and coated with two layers of universaltm mold release (smooth-on, reynolds advanced materials, chicago, il). tpu fabric was heat-sealed to form 6 x 10 cm bladders, which were manually inserted into the cavities of the cured vytaflextm 20. each bladder was heat-sealed to a 3d printed tpu fitting made for 6.4 mm tubing. parafilm secured the seal at the tube fitting (figure 1e). preliminary testing showed each bladder could hold 60 ml of water without leaking. given a fully-contracted limb volume of 1,330 ml, full bladder inflation would theoretically yield ±6.8% volume adjustability, meeting design requirements. bladders were connected to a motorized syringe system, controlled using a linear actuator and arduino microcontroller. the motor offered a torque of 1.9 nm, and power of 36 w per rotation. from preliminary testing, each syringe was expected to withstand a maximum fluid pressure of 200-250 kpa from the bladders at full capacity. to reduce costs, all three syringes were controlled with a single motor. if desired, each syringe can be controlled by its own motor. the total cost for all parts is less than cad 400. parametric design files of the molds, a bill of materials and arduino code are available on github: https://github.com/decisionics/biofideliclimb. for performance evaluation, the limb was placed in a rigid 3d printed pla socket (5 mm wall thickness). the socket’s inner geometry matched that of the fully-contracted limb. bladders were then expanded and contracted at various https://doi.org/10.33137/cpoj.v8i2.45759 https://github.com/decisionics/biofideliclimb 3 phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 canadian prosthetics & orthotics journal issn: 2561-987x a biofidelic mock residual limb for prosthetic socket testing phillips et al., 2025 rates. two f-socket™ sensors (figure 1f) from versatek (tekscan inc., south boston, ma) were placed between the limb and socket at two bladder locations (figure 1g and 1h) to read interfacial pressure. a maximum of two sensors could be used simultaneously with our 2-cuff f-socket™ versatek system (tekscan inc., south boston, ma). at full contraction, an average pressure on the limb of 3-5 kpa was read, which was deemed suitable for a loosely fitted socket.25 the full system set-up is shown in figure 1i. protocol for evaluating adjustability the bladders theoretically allow for a ±6.8% volume change; however, this may not directly reflect total limb volume change since bladders may, to some extent, compress surrounding urethane without significantly increasing overall limb size. to quantify the relation between bladder volume and limb volume, limb volume was measured at bladder volumes from 0-180 ml using circumferential measurements taken at 2.5 cm intervals along the length of the limb. as shown in figure 2a, bladders must be fully expanded to achieve the desired ±5% limb volume change. the biofidelic limb was subjected to four different volume change rates inside the socket: 1) a slow rate over 24 hours, 2) moderate rate over 3 hours, 3) fast rate over 30 minutes, and 4) very fast rate over 3 minutes. tests started with the limb at its fully contracted size, then volume increased to its fully-expanded size, was held, then contracted back to its original volume (figure 2b). the limb’s behaviour (detected by measuring interfacial pressures) across different total volume change amounts was assessed by conducting the slow (0.01%/min), figure 1: design overview. a) step one: casting the core with vytaflextm 60 around an aluminum mandrel. b) mold set-up for casting the outer layer. the bladder cavity molds are held in place by clipping into the lid. the wall molds were separated to ease mold removal postcuring. c) step two: casting the outer layer with vytaflextm 20. d) final casted limb. e) tpu bladder. f) f-socket sensor, 0.15 mm thin. g) sensor placement on the limb before donning the rigid socket. h) top view schematic of sensor placement on the limb. i) full system with the biofidelic mock limb, rigid socket, and motorized syringe system. only one f-socket sensor is shown for clarity. bladder cavity molds vytaflex 60 core pla outer wall molds lid lid connections to bladder cavity molds 6 cm 10 cm parafilm at tpu fitting tubing pla inner mold vytaflex 60 clamp aluminum mandrel (∅ = 30mm) vytaflex 20 bladder cavities vytaflex 60 a b d e sensor 2sensor 1 rigid socket bladders bladder sensor 1 sensor 2 20 cm 8 cm f motorized syringe system arduino & motor driver tubing f-socket sensor rigid socket computer ig h vytaflex 20 outer layer vytaflex 60 core c https://doi.org/10.33137/cpoj.v8i2.45759 4 phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 canadian prosthetics & orthotics journal issn: 2561-987x a biofidelic mock residual limb for prosthetic socket testing phillips et al., 2025 moderate (0.08%/min), fast (0.5%/min) and very fast (5%/min) tests for volume changes between -2.5% and +2.5%. volume changes of ±5% were also tested; however, due to resource constraints of the study, this was limited to fast and very fast rates conducted at double speed (1%/min and 10%/min, respectively). furthermore, a variable-rate protocol was tested that cycled the limb through different volume change rates (figure 2b). this assessed the system’s ability to vary both the rate and direction of syringe motion in a non-sequential manner, simulating potential complex volume change patterns that might occur over periods of time involving a combination of activities such as walking, sitting and standing.1,19,23 tests were repeated three times. coefficient of variation (cv = standard deviation/mean × 100%) was calculated to quantify repeatability among volume change rates, among repeat tests at the same volume change rate, and between the two sensors to quantify symmetry of volume change at two bladder locations. interpreting the f-socket pressure readings the f-socket sensors are marketed for one-time use, and experience significant drift over a period of 20 minutes.26-28 however, due to the high cost of each sensor, only one set of sensors was used for all tests, in which the sensors were loaded over three days. precise pressure magnitudes were not necessary in this study; instead, analyzing patterns of pressure changes sufficed to evaluate the functionality of the limb through metrics like repeatability, hysteresis, and symmetry. therefore, results are normalized to the maximum pressure reached in each test to allow for comparison between tests. each pressure recording is an average reading across all sensels of the sensor in contact with the bladder. results effect of volume flow rate on pressure distribution volume flow rate had little effect on interfacial pressure distribution and rate of pressure change across all testing cycles. figure 3a shows similar trends in normalized pressure for ±2.5% volume change, regardless of whether the change occurred at a slow, moderate, fast or very fast rate (average (sd) and maximum cv among rates: 5.8% (3.2%) and 12.7%). although pressure magnitudes may vary due to sensor drift, heat maps in figure 3b show similar pressure distributions among test rates at various stages in the testing cycle. the measured pressure values during the very fast test (which was performed first, and therefore should have accurate pressure readings) are within the range of values reported in the literature on pressures in tight-fitted sockets,29 showing local pressures of approximately 200 kpa. however, long-term sensor drift prevented direct, quantitative comparison of pressure magnitudes in this study and those in the literature. the extent of drift over a 24-hour period can be estimated by comparing peak pressures in figure 3b between tests: the very fast and moderate tests were performed 24 hours apart (very fast and fast were performed on the same day), as were the moderate and slow tests. in both cases, the observed drift was approximately 20% over 24 hours, underscoring its significance and the need to normalize pressure values. figure 2: a) relation between limb volume [ml] and bladder volume [ml] to measure the bladder volume required to obtain a ±5% limb volume change. b) testing protocol (limb volume change [%] vs. time) for constant (top) and variable (bottom) rates of change test procedures. 1320 1340 1360 1380 1400 1420 1440 1460 1480 0 45 90 135 180 l im b v o lu m e [ m l ] bladder volume [ml] 0% volume change periodtest 8 hrsslow 1 hrmoderate 10 minsfast 1 minvery fast hold increase decrease period constant rate test procedure: time (min): fully expanded fully contracted neutral -2.5% or -5% 0% +2.5% or 5% fully contracted neutral 0% -2.5% +2.5% +1.5% 0% -1.75% 0 10 20 2111 13 23 25 variable rate test procedure: volume: +5% -5% a b https://doi.org/10.33137/cpoj.v8i2.45759 5 phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 canadian prosthetics & orthotics journal issn: 2561-987x a biofidelic mock residual limb for prosthetic socket testing phillips et al., 2025 repeatability and hysteresis in volume adjustability tests were repeatable at all flow rates (slow was not repeated due to long test times required) and the variable cycle test (figure 4a-d). the largest cv of 10.4% (variable test, figure 4d) corresponds to a pressure magnitude of approximately 6 kpa. for the variable test, pressure change was only detectable when approximately +1.5% volume change was achieved, therefore only the peak at 20 seconds and the hold at 21 seconds are visible in figure 4d. sensor malfunction occurred during the final test at the fast rate for ±5% volume change, which is depicted in figure 4b. pressure measurements in figure 4a and 4b are normalized to the maximum pressure in the ±5% test. figure 4e and 4f show similar hysteresis curves between ±2.5% and ±5% tests, verifying that limb volume changed in a similar fashion regardless of start and end volumes. the slight variation in pressure readings between ±2.5% and ±5% tests could be attributed to sensor drift or a minor difference in limb placement in the socket between tests. the relatively small hysteresis at each test rate (figure 4e4h) is confirmed by similar pressure distributions between points 1 and 5, and points 2 and 4 in figure 3b. any hysteresis could stem from hysteresis in the urethane, tpu bladder elasticity, or sensor drift. symmetry between two adjustable areas volume change symmetry was analyzed to identify potential manufacturing variances among the cavities or bladders. figure 5 shows the pressure over time for both sensor locations, illustrating very similar trends and pressure distributions. small variations seen are expected due to the manual nature of the manufacturing process. discussion the biofidelic limb enables a controlled, bench-top testing method for real-time evaluation of prosthetic sockets fitted to residual limbs experiencing volume fluctuations of up to ±5%. the value of bench-top testing has also been recognized by mcgrath et al.,14 who developed a mock limb capable of simulating residual limb perspiration. constructed from readily available materials for less than cad 400, the biofidelic limb presented in this study offers many potential adaptations and alternative applications, as outlined in this discussion. while the design met all predetermined design criteria, key study limitations are also addressed below. potential design adaptations in this study, specific materials and geometries were selected, but these can be adapted based on user needs. for example, a transfemoral limb model could have a greater diameter and height, with a thicker outer layer of the soft vytaflextm 20 urethane (or with urethane having a lower hardness and/or modulus) to better resemble the softer tissue often found in a transfemoral vs. transtibial residual limb. additionally, a network of smaller bladder channels could be used to more closely resemble the flow of interstitial fluid within the limb. to promote replication and adaption, design files are provided on github: https://github.com/decisionics/biofideliclimb. figure 3: a) normalized pressure [%] vs. cycle time [% full cycle] for different volume flow rates, measured from one f-socket sensor. b) pressure distribution maps shown at (1) -2.5% and (2) 0% during expansion, (3) +2.5%, then (4) 0% and (5) -2.5% during contraction. kpa 208 192 176 160 144 128 112 96 80 64 48 32 16 ≥ 0 fast 1 2 3 4 5 moderate slow% full cycle increase hold decrease % m a x im u m p re s s u re 3 2 1 4 5 slow moderate fast very fast a b very fast 100 80 60 40 20 0 0 20 40 60 80 100 https://doi.org/10.33137/cpoj.v8i2.45759 https://github.com/decisionics/biofideliclimb 6 phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 canadian prosthetics & orthotics journal issn: 2561-987x a biofidelic mock residual limb for prosthetic socket testing phillips et al., 2025 the deformation of the soft urethane (vytaflextm 20) surrounding the bladders is complex and was not investigated in this study. indentation tests of the soft material used for the limb would help quantify its behaviour, as done by rankin et al.,12 enabling a material-driven and performance-based design approach to optimize bladder placement and size, given the intended anatomical shape of the limb. nonetheless, we expect that placing the bladders closer to the surface would produce a stiffer limb with a steeper pressure response, especially at smaller volumes. the mandrel serves to mimic bone, but can also apply load for any load-bearing testing, which would, in general, increase interfacial pressure. for example, understanding effects on suspension from a fluctuating limb under load may be of interest, as it would expand on work by quinlan et al.24 who previously evaluated the effects of textured socket surfaces on suspension using a static mock limb under load. mcgrath et al.14 also evaluated their mock limb under loads that simulated the stance and swing phases of gait. additionally, the rigid socket restricted limb expansion, and the stiffness of this socket affects the measured pressure distribution. therefore, it is important to note the socket stiffness and applied load, especially if a rigid socket is used as a control comparison to an adjustable socket. study limitations our bladders were initially designed to accommodate a ±6.8% limb volume change, but achieved only ±5% due to nonlinear limb-bladder volume scaling, causing very little overall volume change with initial bladder expansion. this is likely due to the difference in compressibility between the soft outer urethane and the water-filled bladders. as the bladders expand from a small initial volume, the surrounding outer urethane is compressed. then, once a certain bladder volume is reached, the surrounding urethane has stiffened enough that overall limb volume increases more proportionally with further bladder expansion. further work is required to verify this hypothesis, including indentation tests to verify how the urethane stiffness varies as a function of bladder volume. a key limitation of the study was that most tests were limited to ±2.5% volume change due to uncertainty in the heat-seal strength of the bladders at full expansion. while this volume range partially meets the target design criteria, the limited ±5% tests conducted still verified the biofidelic limb’s functionality. since results at ±2.5% and ±5% were comparable for the fast and very fast tests, it is reasonable to expect that the ±2.5% tests for slow and moderate can be generalized to the ±5% range. however, future designs should include a greater bladder capacity to ensure a safety margin, and the long-term bladder strength at full expansion, especially at heat-sealed joints, is a critical area for future evaluation. the long-term use of the sensing system meant pressure magnitudes could not be reported or compared between tests; thus, pressures were normalized in the study to address this limitation. furthermore, the sensor drift prevented any direct comparison of pressure magnitudes in this study to those in the literature. despite this, using normalized pressures met the validation goals of the study because the trends, repeatability, and relative changes in figure 4: repeatability of normalized pressure [%] vs. time [min], for a) very fast, b) fast, c) moderate and d) variable tests. shaded regions show variation among three trials. cvs are reported as: average cv (standard deviation), maximum cv over the cycle, in [%]. sample hysteresis curves of normalized pressure [%] vs. change in limb volume [%], for e) very fast, f) fast, g) moderate and h) slow tests. * final test omitted in cv calculation. 0 25 50 75 100 0 60 120 180 % m a x im u m p re s s u re time [s] 100 75 50 25 % m a x im u m p re s s u re 0 1 2 3 time [min] 0 very fast ±5%, 10%/min cv: 2.8 (1.1), max 6.8 ±2.5%, 5%/min cv: 0.4 (0.2), max 2.7 0 25 50 75 100 0 600 1200 1800 100 75 50 25 % m a x im u m p re s s u re 0 10 20 30 time [min] 0 fast ±5%, 1%/min cv: 4.1 (2.4), max 7.8 * ±2.5%, 0.5%/min cv: 5.7 (3.4), max 7.7 final test 0 100 -5 0 5 % m a x im u m p re s s u re limb volume [%] 0 25 50 75 100 -5 -2.5 0 2.5 5 % m a x im u m p re s s u re change in limb volume [%] fast ±5%, 1%/min ±2.5%, 0.5%/min 0 100 -5 0 5 % m a x im u m p re s s u re limb volume [%] 0 25 50 75 100 -5 -2.5 0 2.5 5 % m a x im u m p re s s u re change in limb volume [%] very fast ±5%, 10%/min ±2.5%, 5%/min % m a x im u m p re s s u re % m a x im u m p re s s u re 2.5-2.5 2.51.25 change in limb volume [%] 100 75 50 25 0 60 120 180 time [min] 0 100 75 50 25 0 5 15 20 time [min] 0 10 25 % m a x im u m p re s s u re % m a x im u m p re s s u re a b ±2.5%, 0.08%/min cv: 3.9 (2.0), max 8.7 moderate c cv: 4.2 (2.2), max 10.4 variable d e f g h 100 75 50 25 0 -1.25 0 ±2.5%, 0.08%/min moderate -2.5 -1.25 0 1.25 change in limb volume [%] ±2.5%, 0.01%/min slow100 75 50 25 0 https://doi.org/10.33137/cpoj.v8i2.45759 7 phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 canadian prosthetics & orthotics journal issn: 2561-987x a biofidelic mock residual limb for prosthetic socket testing phillips et al., 2025 pressure over the volume-change cycles remained consistent across repeated trials. this indicates that, even without pressure magnitudes, the system reliably captured the relation between changes in limb volume and interfacial pressure, which was an essential requirement for evaluating the limb’s performance. for applications requiring absolute pressure, sensors should be calibrated before each test or replaced with new sensors following every test. applications the biofidelic limb can be used to evaluate sockets (both static and adjustable) fitted to residual limbs with volume fluctuations of up to ±5% in real time. clinical outcomes of sockets (e.g., pistoning, suspension, and interfacial pressures) can be evaluated by adjusting the size of the limb, rather than swapping out sockets or limbs of different sizes.2,25 furthermore, the detailed design description provided in this study expands on the work of paterno et al.,16 who developed a similar limb but did not provide design details. the methods presented here could be combined with those from mcgrath et al.14 to develop a biofidelic limb capable of both volume fluctuation and perspiration. beyond prosthetics, the biofidelic limb may support testing the fit of footwear, compression garments or orthotics.30,31 load-bearing testing is also facilitated via the internal mandrel. conclusion this work presents the design and fabrication procedure of a biofidelic limb used for testing prosthetic sockets, with adjustable water-filled bladders that enable controllable, repeatable volume changes of up to ±5% of limb volume. the biofidelic limb demonstrated high repeatability (cv < 10.4%) and adequate symmetry (cv < 11.2%) between two bladders placed on two areas of the limb. despite its limitations, the sensing tool effectively confirmed the biofidelic limb’s functionality. the proposed design can be tailored for different anatomies, volume change ranges, materials, and is easily manufactured with readily available materials. furthermore, it allows for controllable bench-top testing during prototyping of devices designed for volume adjustment, such as adjustable prosthetic sockets, eliminating the need for resource-intensive clinical trials. acknowledgements the authors would like to thank the war amps for their funding support. declaration of conflicting interests the authors report no conflict of interest. authors’ contribution • clara phillips: conceptualization, methodology, validation, data curation, writingoriginal draft, visualization. • aaryan nagpal: methodology, software, data curation, writing – original draft. • fae azhari: conceptualization, writing – review & editing, supervision. figure 5: normalized pressure [%] vs. cycle time [% full cycle] for sample very fast and fast tests (over ±5% volume change) measured at two bladder locations with two f-socket sensors. cvs are reported as the average (standard deviation), maximum cv over the cycle, in [%]. 0 20 40 60 80 100 0 20 40 60 80 100 % m a x im u m p re s s u re % full cycle fast very fast sensor 1 (±5%) sensor 2 (±5%) cv: 3.1 (1.6), 5.3 sensor 1 (±5%) sensor 2 (±5%) cv: 6.0 (3.9), 11.2 https://doi.org/10.33137/cpoj.v8i2.45759 https://www.waramps.ca/home/ 8 phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 canadian prosthetics & orthotics journal issn: 2561-987x a biofidelic mock residual limb for prosthetic socket testing phillips et al., 2025 sources of support this work was supported by the war amps amputation research grant. references 1.youngblood rt, hafner bj, allyn kj, cagle jc, hinrichs p, redd c, et al. effects of activity intensity, time, and intermittent doffing on daily limb fluid volume change in people with transtibial amputation. prosthet orthot int. 2018;43:28–38. doi:10.1177/ 0309364618785729 2.seo jh, lee hj, seo dw, lee dk, kwon ow, kwak mk, et al. a prosthetic socket with active volume compensation for amputated lower limb. sensors (basel). 2021;21:1–17. doi:10.3390/ s21020407 3.paternò l, ibrahimi m, gruppioni e, menciassi a, ricotti l. sockets for limb prostheses: a review of existing technologies and open challenges. ieee trans biomed eng. 2018;65:1996–2010. doi:10.1109/tbme.2017.2775100 4.pascale ba, potter bk. residual limb complications and management strategies. cur phys med rehab rep. 2014;2:241– 249. doi:10.1007/s40141-014-0063-0 5.barr ea, ebbs kbs, wensman j, gutierrez a, rosenblatt nj, gates dh. a survey of prosthetists’ perspectives on adjustablevolume lower-limb prosthetic sockets. j prosthetics orthot. 2022;34(4):233-240. doi: 10.1097/jpo.0000000000000376 6.baldock m, pickard n, prince m, kirkwood s, chadwell a, howard d, et al. adjustable prosthetic sockets: a systematic review of industrial and research design characteristics and their justifications. j neuroeng rehabil. 2023;20:147. doi: 10.1186/ s12984-023-01270-0 7.klenow td, schulz j. adjustable-volume prosthetic sockets: market overview and value propositions. can prosthetics orthot j. 2021;4(2):35208. doi:10.33137/cpoj.v4i2.35208 8.baer g, fatone s. scoping review of mechanical testing of the structural and material properties of lower-limb prosthetic sockets. j prosthetics orthot. 2022;35(2):e37-e47. doi:10.1097/ jpo.0000000000000424 9.gariboldi f, cutti ag, fatone s, nickel e, dickinson a, steer j, et al. mechanical testing of transtibial prosthetic sockets: a discussion paper from the american orthotic and prosthetic association socket guidance workgroup. prosthet orthot int. 2023;47(1):3-12. doi: 10.1097/pxr.0000000000000222 10.gariboldi f, pasquarelli d. cutti ag. structural testing of lowerlimb prosthetic sockets: a systematic review. med eng phys 2022;99:103742. doi: 10.1016/j.medengphy.2021.103742 11.international organization for standardization. prosthetics — structural testing of lower-limb prostheses — requirements and test methods. 2016 12.rankin k, steer j, paton j, mavrogordato m, marter a, worsley p, et al. developing an analogue residual limb for comparative dvc analysis of transtibial prosthetic socket designs. materials (basel). 2020;13(18):3955. doi: 10.3390/ma13183955 13.mcgrath mp, gao j, tang j, laszczak p, jiang l, bader d, et al. development of a residuum/socket interface simulator for lower limb prosthetics. proc inst mech eng part h j eng med. 2017;231(3): 235–242. doi: 10.1177/0954411917690764 14.mcgrath m, davies kc, gallego a, laszczak p, tang j, zahedi s, et al. using a sweating residuum/socket interface simulator for the evaluation of sweat management liners in lower limb prosthetics. can prosthet orthot j. 2021;4(1):35213. doi: 10.33137/cpoj.v4i1.35213 15.murdock, r. development of a prosthetic biofeedback method and device to measure quality of fit for trans-tibial amputees. (university of waterloo, 2021) 16.paterno l, filosa m, anselmino e, cecere a, dell’agnello f, gruppioni e. soft transfemoral prosthetic socket with sensing and augmenting feedback: a case study. ieee trans med robot bionics. 2024;6(2):536–547. doi: 10.1109/tmrb.2024.3381378 17.sanders je, fatone s. residual limb volume change: systematic review of measurement and management. j rehabil res dev. 2011;48(8): 949–986. doi: 10.1682/jrrd.2010.09.0189 18.paternò l, ibrahimi m, rosini e, menfi g, monaco v, gruppioni e, et al. residual limb volume fluctuations in transfemoral amputees. sci reports. 2021; 11:12273. doi: 10.1038/s41598021-91647-9 19.sanders je, cagle jc, harrison ds, myers tr, allyn kj. how does adding and removing liquid from socket bladders affect residual limb fluid volume? j rehabil res dev. 2013;50(6):845860. doi:10.1682/jrrd.2012.06.0121 20.dean rc, mayor mb, nelson df, braley cs, blanchard mw. dynamic variable geometry fitting system for use with a body appliance. us patent us20020099450a1. 2003. available from: https://patents.google.com/patent/us20020099450a1/en. 21.d’silva k, hafner bj, allyn kj, sanders je. self-reported prosthetic sock use among persons with transtibial amputation. prosthet orthot int. 2013; 38(4):321–331. doi: 10.1177/ 0309364613499064 22.fernie gr, holliday pj. volume fluctuations in the residual limbs of lower limb amputees. arch phys med rehabil. 1982;63(4): 162– 165 23.sanders je, hartley tl, phillips rh, ciol ma, hafner bj, allyn kj, et al. does temporary socket removal affect residual limb fluid volume of trans-tibial amputees? prosthet orthot int. 2015;40(3):320–328. doi:10.1177/0309364614568413 24.quinlan j, yohay j, subramanian v, poziembo b, fatone s. using mechanical testing to assess the effect of lower-limb prosthetic socket texturing on longitudinal suspension. plos one. 2020;15(8):e0237841. doi: 10.1371/journal.pone.0237841 25.karamousadakis m, porichis a, ottikkutti s, chen d. a sensorbased decision support system for transfemoral socket rectification. sensors. 2021;21(11):3743. doi: 10.3390/s21113743 26.swanson ec, weathersby ej, cagle jc, sanders je. evaluation of force sensing resistors for the measurement of interface pressures in lower limb prosthetics. j biomech eng. 2019;141(10):1010091-10100913. doi:10.1115/1.4043561 https://doi.org/10.33137/cpoj.v8i2.45759 https://www.waramps.ca/home/ https://patents.google.com/patent/us20020099450a1/en 9 phillips c, nagpal a, azhari f. a biofidelic mock residual limb for prosthetic socket testing. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 1. https://doi.org/10.33137/cpoj.v8i2.45759 canadian prosthetics & orthotics journal issn: 2561-987x a biofidelic mock residual limb for prosthetic socket testing phillips et al., 2025 27.komi er, roberts jr, rothberg sj. evaluation of thin, flexible sensors for time-resolved grip force measurement. proc imeche part c j mech eng sci. 2007;221(12). doi:10.1243/ 09544062jmes700 28.young pr, hebert js, marasco pd, carey jp, schofield js. advances in the measurement of prosthetic socket interface mechanics: a review of technology, techniques, and a 20-year update. exp rev med dev. 2023;20(9):729-739. doi: 10.1080/ 17434440.2023.2244418 29.sanders je, jacobsen ak, fergason jr. effects of fluid insert volume changes on socket pressures and shear stresses: case studies from two trans-tibial amputee subjects. prosthet orthot int. 2006;30(3): 257–269. doi: 10.1080/03093640600810266 30.li nw, kwan my, yick kl. graduated compression stocking performance: insights from wearers and development of a costeffective 3d-printed leg mannequin. text res j. 2024;95(11-12). doi: 10.1177/00405175241297170 31.richards cj, steele jr, spinks gm. experimental evaluation and analytical model of the pressure generated by elastic compression garments on a deformable human limb analogue. med eng phys. 2020;83: 93–99. doi: 10.1016/ j.medengphy.2020.05.015 https://doi.org/10.33137/cpoj.v8i2.45759 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 1 2024 research article galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i1.43790 1 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 research article exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals galbert a, buis a* department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. introduction upper limb impairment can affect anyone at any time. age, injury, disease, and other conditions may present a person with motor impairments such as weakness, paralysis, spasticity, tremors and dystonia. they may have a full recovery to independent life through rehabilitation, but others may require further support. when upper limb motor impairments affect the hands and wrist, which is the focus of this study, activities of daily living (adls) are negatively impacted. functional tasks such as self-care, cooking, and working may be affected which can reduce community engagement and quality of life.1,2 in addition, a person may require regular support from caretakers and allied health professionals, these visits and other expenses present financial, resource and time burdens on the medical sector.3-6 assistive devices can be prescribed to support persons who require additional functionality and prehension in their upper limbs. assistive devices have a history of use in medical and occupational fields.7,8 they can range from orthotics to complex machinery such as an exoskeleton. orthotic devices such as splints and braces are used to stabilise and support the limb which aids in maintaining proper alignment and preventing further injury. orthotic devices can be custom-made or prefabricated. exoskeletons are robotic assistive devices which support and enhance movements, open access abstract background: actuated devices can be beneficial for individuals with upper limb muscle weakness, offering extra force and grip. utilising this type of assistive device can facilitate daily activities, thereby enhancing independence and overall quality of life. the development of actuated assistive devices has been growing, and current literature shows promise in their clinical use. however, they are not yet medically recommended by global guidelines and councils. studies have suggested why assistive devices have barriers to access, but actuated devices have not been a focus in these discussions. objective(s): to address this issue, a survey was conducted among professionals who prescribe and assess upper limb assistive devices. the survey aimed to gather their opinions and quantify the factors that might contribute to the limited use of actuated devices in the field. methodology: a web-based cross-sectional study was designed using qualtrics, contained 25 items and was conducted between october 2023 and january 2024. the survey was piloted, validated, and ethically approved. results were statistically analysed, and open questions underwent thematic analysis. findings: 87 allied health professionals (ahps) contributed to the survey, with a completion rate of 69% (60/87). survey respondents predominately worked from the usa (72%). the survey revealed that 66% of respondents felt they did not have sufficient access to assistive devices and 58% indicated that outcome measures could be improved. they also noted that actuated devices needed to better meet user-centric needs. barriers to prescribing these devices included a lack of awareness, experience and standardised prescription methods. in addition, the limited time with patients made decision-making and validation of an actuated device difficult. conclusion: ahp’s have experience prescribing assistive devices but do not have access, knowledge, or clinical methods to assess the use of actuated devices. future designs for actuated devices should focus on wearability, comfort, user satisfaction, safety and ease of use. article info received: july 30, 2024 accepted: september 13, 2024 published: september 22, 2024 citation galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.4 3790 keywords assistive device, exoskeletons, actuated, powered, allied health professionals, upper limb, design, outcome measures, orthosis, rehabilitation, satisfaction, survey * corresponding author: professor arjan buis, phd department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. e-mail: arjan.buis@strath.ac.uk orcid id: https://orcid.org/0000-0003-3947-293x journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 1, article no.4. 2024 https://doi.org/10.33137/cpoj.v7i1.43790 https://doi.org/10.33137/cpoj.v7i1.43790 https://doi.org/10.33137/cpoj.v7i1.43790 mailto:arjan.buis@strath.ac.uk https://orcid.org/0000-0003-3947-293x https://jps.library.utoronto.ca/index.php/cpoj/index 2 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 they have been used in rehabilitation clinics to aid in restoring motor function. other assistive devices can include adaptive equipment, arm supports, and mechanical hand and finger exercisers to improve grip through repetitive exercises. the level of support and type of tools should reflect the user’s needs. therefore, an actuated, powered, and active device would be appropriate for users needing additional strength during everyday tasks. these devices provide additional force using motors to attain the power requirements for adls. yet, these devices are not listed as recommended tools in guidelines such as the nice guidelines.9 current literature on assistive technology in global and lowand middle-income countries has reported barriers such as cost, weight, validation, and poor market conditions.10,11 however, actuated and powered devices for the upper limb have not been specifically highlighted in these reports. due to the recent emergence of actuated assistive devices and the rapid pace of ongoing research, there is a lack of longitudinal studies validating their clinical efficacy.12 to explore why actuated assistive devices for hand motor impairments are not recommended, a cross-sectional survey was conducted to gather opinions from stakeholders who assess and prescribe assistive devices. stakeholder opinion on assistive technology has been conducted previously but focused on service providers,13 training needs,14,15 and software applications.16 in addition, literature that has focused on the design and application of assistive devices for upper limb impairment lacked a stakeholder perspective.17 these stakeholders, who support and understand user needs, can provide valuable insights into design factors and outcome measures, aiding in the development and clinical validation of future actuated devices. a cross-sectional survey is a time-efficient and costeffective method for summarizing the population’s relationship to certain characteristics, behaviors, or outcomes. it is an observational study that collects data from a population (in this case, allied health professionals) at a single point in time to assess the prevalence of various outcomes. for this study, the focus is on gathering the population’s opinions on assistive device design and validation methods. cross-sectional studies can be conducted through interviews and surveys, a survey was chosen for its efficiency and accessibility. the study aims to conduct a cross-sectional survey to explore barriers and limitations of actuated assistive devices with a 2-part focus on trends in current assistive devices and recommended outcome measures. the objectives include quantifying important design factors, and investigating trends in assistive devices and outcome measures used for persons with motor impairment in the upper limb. this will contribute to the field of actuated assistive devices and provide a basis for future research in new designs and validation processes to improve prescription. methodology recruitment an online cross-sectional survey was designed and conducted from october 2023 to january 2024 in qualtrics, a web-based software for creating surveys. the research was approved by the university of strathclyde's departmental ethical committee (dec.biomed.2023.348). the participation information sheet and consent forms were integrated into the survey questions (found in the appendix). all collected data was anonymized, and data protection and risk assessment protocols were followed. inclusions for participation in the study were limited to those who currently work, or have worked, in the field of upper limb assistive devices, individuals with first or second-hand experience with users requiring assistive devices, who understand english for academic discussion, and those with access to a device capable of completing the online survey. individuals who have not practised in this field within the last 5 years were excluded. four associations in the appropriate fields of the study were contacted for dissemination of the survey. these included the american society of hand therapists (asht), the british association of hand therapists (baht), the british association of prosthetics and orthotics (bapo), and the international society of prosthetics and orthotics (ispo). as part of the approval for dissemination, each association included a validation and piloting process. asht required ethical approval, and the survey was reviewed with feedback from 2 members of the research division. baht reviewed the survey with feedback from 2 clinical evidence committee members using the harvard university program on survey research (psr) questionnaire.18 bapo required ethical approval and pilottested the survey with 9 members of their research committee. ispo also required ethical approval. the survey was internally validated using the checklist for reporting results of internet e-surveys (cherries) by eysenbach19 and followed siny tsang guidelines for developing, translating, and validating a questionnaire.20 once the survey had been approved, the associations disseminated the survey link via posters, newsletters, and mailing lists. we also used social media platforms and conferences to advertise the study. no incentives were provided to fill out the online survey. survey design the survey was designed in a structured format comprising 25 items which can be found in the appendix: 4 open questions, 10 closed questions, 10 multiple choices, and 1 https://doi.org/10.33137/cpoj.v7i1.43790 https://asht.org/ https://www.hand-therapy.co.uk/ https://www.bapo.com/ https://www.bapo.com/ https://www.ispoint.org/ 3 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 likert scale. it starts with the participant information sheet, followed by the consent form. the survey then consisted of 4 main sections focusing on ahps' perspectives on assistive devices and a second part on the rationale for the lack of prescription. demographics this section included questions related to participants’ occupations, experience in the field (in years), country of work, and the patient population they interact with. allied health professionals may have multiple roles, therefore, occupation selection allows for multiple choice. actuated devices participants were asked if they prescribed and or assessed assistive devices for hands and wrists, this was required for adaptive questions further on in the survey. they were then asked if they recognised and had experience with the assistive devices listed compiled from current literature21 and discussions with clinicians who did not pilot the survey. the list was designed to include a range of devices from static casts to robotic actuated devices. the inclusion of non-actuated devices in the list was important to reduce response bias. those who did not prescribe or assess assistive devices had the opportunity to give their perspectives on why they do not. this section also asked for opinions on access to devices and how they are financed. design factors design factors were based on a modified quebec user evaluation of satisfaction with assistive technology (quest 2.0).22 additional modifications included the removal of “access” for “service” items, changes to the ranking labels from “satisfaction” levels to “level of importance”, and item labels were adjusted to better suit actuated devices such as adding mechanical power. participants would be asked for their opinions and experiences on assistive devices, these open-question responses would undergo thematic analysis to extract additional design factors missed by the quest 2.0. outcome measures this section asked participants if they have experience using outcome measures and let them pick which they had used and recommend from a list made from results of a dataset21 and literature.23 respondents were then asked to identify the main limitations to assessing outcomes for patients and if they believed outcome measures were useful and could be improved. validity, bias, and limitations the validity of the survey was assessed by correspondents, asht and baht committee members, using respected guidelines and questionnaires. these included the psr questionnaire,18 cherries19 and subjective judgement from persons in the relevant fields. due to time constraints, test-retest reliability was not conducted. to reduce the effect of this limitation, time limits were removed, and the questionnaire was designed to take less than 15 minutes.24 estimated time found using the qualtrics predicted duration programme. the absence of a time limit can aid in higher completion rates as respondents can complete the survey at their own pace.25 coverage bias was expected due to requiring english speakers and an internet connection. in addition, although the survey was disseminated across four different associations via a mailing list, members may have unsubscribed. coverage bias could not be avoided but was mitigated as best as possible. to mitigate sampling bias, the target population and sampling frame were clearly defined within the inclusion criteria. non-response and measurement errors were reduced by circulating the survey, varying question styles, and allowing neutral responses to questions. data analysis the demographic features of participants were analysed, and participants were grouped by discipline. interactions between nominal data were summarized to determine significant trends. multiple-choice questions were analysed using cross-tabulation. these quantitative analyses were performed using microsoft excel (version 2408) and python (3.12) in visual studio. open-ended questions were coded using thematic analysis following braun and clarke's methods.26 the process followed an inductive approach in which the data determined the themes. as the open questions were not required, the response rate tended to be lower therefore latent deduction aided in theming the subtext and assumptions underlying the data. each open question was analysed separately. themes were then compared across relevant sections to provide qualitative evidence. the thematic analyses were performed by hand on microsoft excel. results participants 87 unique responses were collected, with a 69% (60/87) completion rate. all analyses are on the 60 fully completed responses, participant demographic features are present in table 1. years of experience in the field ranged from 3 months to 52 years (mean=24.42, sd=13.68). ahps may have multiple job roles, therefore when asking for occupation, participants could choose multiple options leading to 105 total responses from the 60 participants including occupational therapists (ot) (44%, 46/105), https://doi.org/10.33137/cpoj.v7i1.43790 4 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 hand therapists (ht) (39%, 41/105), orthotist (10%, 11/105), prosthetist (3%, 3/105), health care assistant (hca) (1%, 1/105), physiotherapist (1%, 1/105), rehabilitation specialist (1%, 1/105), and unspecified other (1%, 1/105). the respondents interacted with a range of patient populations, as presented in table 1. the top prevalent patient conditions included carpal tunnel syndrome (87%, 52/60), epicondylitis (80%, 48/60), peripheral neuropathy (77%, 46/60), stroke (47%, 28/60) and parkinson's disease (37%, 22/60). muscle weakness tends to be a symptom in these conditions, but pain is also a major factor when deciding on treatment and management of conditions. current practices may recommend splinting and bracing for the affected upper limb. this approach is well-researched for the patient conditions supported by the respondents. the respondents primarily worked from the usa (72%, 43/60), followed by the uk (18%, 11/60); switzerland, south africa, nigeria, and ireland each had 1 survey taker, and 2 participants did not respond to this question. a noticeable usa-centric participation group influenced the results, particularly when respondents were asked about the funding mechanisms for assistive devices. multiple funding sources can be used within a medical department, so respondents were given the option to select all applicable sources, resulting in 80 responses. private health insurance was the most prevalent funding source, cited by 43% (34/80) of respondents, followed by self-funded options at 34% (27/80). this distribution reflects the structure of the u.s. medical sector, where a universal healthcare system is not in place. assistive devices many of the assistive devices recognised in table 2 used electrical stimulation (70%, 42/60); the tens stimulator (65%, 39/60) was the most recognised assistive device, and respondents also had the most experience using it (45%, 27/60). in comparison, ahps did not have experience using powered and actuated devices (15%, 9/60). myopro orthosis was the most recognised and used actuated device. the myopro is an american device which uses electromyography (emg) to trigger upper limb movement. the discrepancies in table 2 may be due to response errors when completing the survey. 13 respondents did not recognize any of the listed devices. however, 62% of these respondents (8/13) indicated that they prescribe assistive devices. this suggests that the curated list of assistive devices did not capture their experiences. many ahps responded negatively (50%, 30/60) or were unsure (17%, 10/60) when asked if they had enough access to assistive devices. surprisingly, only 6 people felt they “definitely” had enough access to assistive devices. nine participants work in workplaces that do not offer assistive devices. all of them are based in the usa (100%, 9/9) and support patients with carpal tunnel syndrome (100%, 9/9) and epicondylitis (100%, 9/9). the majority are occupational therapists (89%, 8/9). reasons why assistive devices are not offered by this group were extracted from their open-ended responses and analyzed using thematic analysis. from the nine responses, five themes emerged: (1) ahps’ belief that the patient population is not appropriate for devices, (2) the patient population is not large enough, (3) ahps lack exposure to assistive devices, (4) a lack of availability of devices, and (5) the cost of the devices. “not enough clients coming that need them [assistive devices] on a regular basis. if we had a sporadic client needing one, we would research and try to reach out for options” (ot, usa, 32) (occupation, country, experience in years) although this group of respondents did not routinely offer assistive devices in their workplace, the reasons mentioned above overlap with the thematic analysis of the opinions and experiences other ahps had with assistive devices shown in table 3. both thematic analysis (table 3) and the likert responses (figure 1) showed similar factors which affect the prescription of actuated devices. ahps had concerns about devices’ designs not being multifunctional and uncomfortable for users. user-centric factors (as opposed to mechanical factors) such as comfort, satisfaction, safety and ease of use have a strong level of importance across all demographics. yet if the device is too heavy or not versatile enough, the users may adapt to not needing one. when comparing the devices used (table 2) with the factors shown in figure 1, the right balance of these factors is difficult to determine. for instance, weight is considered less important than comfort but ensuring a device’s weight and weight distribution is minimalized is often a physical attribute to determine comfort. outcome measures figure 1 quantifies well-established factors of importance pertaining to design, while table 3 captures themes often forgotten. in table 3, ahps felt that there were unclear prescription methods and a lack of awareness of these devices. to better understand prescription methods, the latter half of the survey focused on outcome measures. when and which types of outcome measures are used are essential for tracking improvements in users’ functionality and validating assistive devices. 71% (43/60) of ahps had experience using outcome measures for upper limb assessment, while 12% (7/60) had some experience and 17% (10/60) had no experience. most respondents (72%, 43/60) found outcome measurement tools useful while the remainder were unsure (17/60). https://doi.org/10.33137/cpoj.v7i1.43790 5 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 table 1: list of participants. id no. occupation(s) work experience (years) country of work patient population(s) interacted with assessor of assistive device? prescribers of assistive devices (rows 1 to 46) 1 hand therapist, occupational therapist 13 united states of america carpal tunnel syndrome, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, stroke yes 2 orthotist 25 united kingdom of great britain and northern ireland carpal tunnel syndrome, cerebral palsy, duchenne muscular dystrophy, multiple sclerosis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke yes 3 hand therapist, occupational therapist 38 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, stroke yes 4 orthotist 7 united kingdom of great britain and northern ireland carpal tunnel syndrome, cerebral palsy, duchenne muscular dystrophy, multiple sclerosis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke yes 5 orthotist 4.5 united kingdom of great britain and northern ireland cerebral palsy, duchenne muscular dystrophy, multiple sclerosis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke, diabetes*, paediatrics* yes 6 occupational therapist 30 united states of america carpal tunnel syndrome, epicondylitis, stroke yes 7 hand therapist, occupational therapist 40 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, stroke, trauma injury* yes 8 hand therapist, occupational therapist 20 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy yes 9 hand therapist 42 united states of america carpal tunnel syndrome, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, trauma injury*, amputation*, laceration repair*, general yes 10 orthotist 0.25 united kingdom of great britain and northern ireland cerebral palsy, multiple sclerosis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke yes 11 hand therapist, occupational therapist 20 united states of america carpal tunnel syndrome, cerebral palsy, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, stroke yes 12 hand therapist 38 switzerland carpal tunnel syndrome, epicondylitis, peripheral neuropathy yes 13 hand therapist, occupational therapist 28 united states of america carpal tunnel syndrome, epicondylitis, trauma injury*, arthritis, general yes 14 hand therapist, occupational therapist, other (please specify) 52 united states of america carpal tunnel syndrome, epicondylitis, parkinson's disease, peripheral neuropathy, trauma injury*, laceration repair* yes 15 hand therapist, occupational therapist 32 united states of america carpal tunnel syndrome, cerebral palsy, epicondylitis, peripheral neuropathy, stroke yes 16 hand therapist, occupational therapist 15 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, stroke, amputation* yes 17 hand therapist, occupational therapist 27 united states of america carpal tunnel syndrome, duchenne muscular dystrophy, epicondylitis, multiple sclerosis, peripheral neuropathy, laceration repairs*, trauma injury*, general yes 18 occupational therapist 29 united states of america carpal tunnel syndrome, epicondylitis, trauma injury* yes 19 hand therapist, occupational therapist 37 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, stroke yes 20 occupational therapist 39 south africa carpal tunnel syndrome, cerebral palsy, duchenne muscular dystrophy, epicondylitis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke, trauma injury*, laceration repair*, general yes 21 occupational therapist 33 united states of america carpal tunnel syndrome, epicondylitis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke, laceration repairs* yes 22 hand therapist, occupational therapist 33 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, stroke yes 23 hand therapist, occupational therapist 32 united states of america carpal tunnel syndrome, epicondylitis yes 24 hand therapist, occupational therapist 28 united states of america carpal tunnel syndrome, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, spinal cord injury yes 25 occupational therapist 23 united kingdom of great britain and northern ireland carpal tunnel syndrome, cerebral palsy, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, stroke, trauma injury* yes 26 hand therapist, occupational therapist 50 united states of america peripheral neuropathy, spinal cord injury, burns*, amputation* yes https://doi.org/10.33137/cpoj.v7i1.43790 6 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 table 1 (continued): list of participants. id no. occupation(s) work experience (years) country of work patient population(s) interacted with assessor of assistive device? prescribers of assistive devices (rows 1 to 46) 27 hand therapist, occupational therapist 33 united states of america carpal tunnel syndrome, cerebral palsy, duchenne muscular dystrophy, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy yes 28 hand therapist, occupational therapist 42 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, laceration repairs*, general* yes 29 occupational therapist 24 united kingdom of great britain and northern ireland carpal tunnel syndrome, epicondylitis, peripheral neuropathy yes 30 hand therapist, occupational therapist 27 united states of america carpal tunnel syndrome, peripheral neuropathy yes 31 hand therapist, occupational therapist 9 united states of america carpal tunnel syndrome, duchenne muscular dystrophy, epicondylitis, multiple sclerosis, peripheral neuropathy, spinal cord injury, stroke yes 32 occupational therapist 22 united kingdom of great britain and northern ireland carpal tunnel syndrome, epicondylitis, peripheral neuropathy yes 33 hand therapist, occupational therapist 42 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, orthopedics*, arthritis* yes 34 hand therapist, occupational therapist 6 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, trauma injury*, orthopedics* yes 35 hand therapist 24 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy yes 36 hand therapist, occupational therapist 40 united states of america carpal tunnel syndrome, epicondylitis, parkinson's disease, peripheral neuropathy yes 37 hand therapist, occupational therapist 50 united states of america spinal cord injury, burns*, amputation*, general* yes 38 hand therapist, occupational therapist 43 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, general*, arthritis* yes 39 orthotist 11 united kingdom of great britain and northern ireland carpal tunnel syndrome, cerebral palsy, duchenne muscular dystrophy, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke yes 40 hand therapist, health care assistant (hca), orthotist, physiotherapist, prosthetist, rehabilitation specialist 3 nigeria cerebral palsy, stroke yes 41 orthotist, prosthetist 29 ireland carpal tunnel syndrome, cerebral palsy, duchenne muscular dystrophy, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke, amputation* yes 42 orthotist 10 united kingdom of great britain and northern ireland carpal tunnel syndrome, cerebral palsy, duchenne muscular dystrophy, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke yes 43 orthotist 12 united kingdom of great britain and northern ireland cerebral palsy, multiple sclerosis, spinal cord injury, stroke yes 44 orthotist, prosthetist 6 united kingdom of great britain and northern ireland cerebral palsy, spinal cord injury, stroke yes 45 hand therapist, occupational therapist 6 united states of america carpal tunnel syndrome, epicondylitis, parkinson's disease, peripheral neuropathy no 46 hand therapist, occupational therapist 9 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy no non-prescribers of assistive devices (rows 47 to 60) 47 hand therapist, occupational therapist 26 united states of america carpal tunnel syndrome, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, stroke, laceration repair* yes 48 hand therapist, occupational therapist 32 united states of america carpal tunnel syndrome, cerebral palsy, epicondylitis, multiple sclerosis, parkinson's disease, peripheral neuropathy, spinal cord injury, stroke yes https://doi.org/10.33137/cpoj.v7i1.43790 7 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 table 1 (continued): list of participants. although the majority found them useful, 58% (35/60) believed outcome measurement tools could be improved. outcome measures may be used for various reasons. therefore, ahps were asked to select all applicable options for when they use outcome measures. results showed that they are used to assess patients’ needs (44%, 48/108), and to evaluate patients during (20%, 22/108) and after (19%, 20/108) the use of assistive devices. they were often not used to evaluate the assistive device (17%, 18/108). survey responses from ahps regarding upper limb outcome measures and tools revealed that many of the measures they had used were not recommended, as shown in table 4. the variety of outcome measures recommended span from simple observational tasks such as the 9hpt to patient-reported outcomes. ahps often recommended an arsenal of outcome measures tests and rarely relied on a singular test to capture hand/wrist assessment. alongside knowing which outcome measures are recommended, participants expressed the limitations of outcome measures. time constraints are often a limitation in the medical sector, and immense pressure is noticed on healthcare providers27 which is reflected in table 5. the results of the thematic analysis, presented in table 6, highlight poor functionality of outcome measures as a recurring theme. improvements were identified and included using handedness, using a bank of adls, including don and doff features, satisfaction levels, and objective tasks as part of the outcome measure. some of the responses in the functionality theme overlap with relevance and documentation. respondents wanted outcome measures to be a method of seeing patients improve, yet choosing which outcome measures to use was an issue. the involvement of funding sources affected the use of outcome measures for three ahps in the usa. some funding sources dictate which outcome measures to use, while others allow ahps to choose as quoted in the financing theme. when these ahps were told which outcome measures to use by a funding source, such as an insurance company, there were negative responses as quoted below: “often outcome measurements are dictated by the company you work for or the insurance plan typically these are not the most effective measurement tools that we have available” (ht/ot, usa, 23) (occupation, country, experience in years) id no. occupation(s) work experience (years) country of work patient population(s) interacted with assessor of assistive device? non-prescribers of assistive devices (rows 47 to 60) 49 occupational therapist 10 united states of america carpal tunnel syndrome, epicondylitis, orthopedics* yes 50 hand therapist, occupational therapist 23 united states of america carpal tunnel syndrome, epicondylitis, parkinson's disease, peripheral neuropathy yes 51 hand therapist, occupational therapist 16 united states of america carpal tunnel syndrome, epicondylitis, multiple sclerosis, peripheral neuropathy, stroke yes 52 occupational therapist 32 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, orthopedics*, laceration repair* no 53 hand therapist, occupational therapist 13 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy no 54 hand therapist, occupational therapist 28 united states of america carpal tunnel syndrome, epicondylitis, general no 55 hand therapist, occupational therapist 1 united states of america carpal tunnel syndrome, epicondylitis, parkinson's disease, peripheral neuropathy, stroke no 56 hand therapist, occupational therapist 34 united states of america carpal tunnel syndrome, epicondylitis, orthopedics* no 57 hand therapist, occupational therapist 37 carpal tunnel syndrome, epicondylitis no 58 hand therapist, occupational therapist 7.5 united states of america carpal tunnel syndrome, osteoarthritis*, trauma injury*, dupuytren* no 59 hand therapist, occupational therapist 12 united states of america carpal tunnel syndrome, epicondylitis, peripheral neuropathy, stroke no 60 orthotist 10 duchenne muscular dystrophy no note: * patient populations abstracted from text response https://doi.org/10.33137/cpoj.v7i1.43790 8 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 *(occupation, country, and experience in years) table 2: assistive devices recognised and used by respondents including their key features. device name type of device device feature count of assistive devices recognised (n) count of assistive devices ahps have working experience using (n) tens stimulator tens passive electrical stimulation 39 27 saebomas anti-gravity support clinical tool 17 8 none 13 8 myopro orthosis powered and actuated device emg control 10 5 exotic exoskeleton powered and actuated device rigid exoskeleton 9 1 rehand rehabilitation software tablet-based 8 2 graspyglove powered and actuated device soft exoskeleton 5 1 hand of hope powered and actuated device emg control 5 0 x-glove powered and actuated device rigid exoskeleton 4 0 jaco assistive robotic arm manual selection 3 2 sem glove powered and actuated device soft exoskeleton 3 0 tenoexo hand exoskeleton powered and actuated device semi-rigid design and emg control 3 0 odstock microstim neuromuscular electrical stimulation emg control 2 2 tiger powered and actuated device table-based interface and rigid 2 0 dtsam orthosis powered and actuated device soft exoskeleton 1 0 fesia grasp device fes emg control 1 0 handy rehab powered and actuated device rigid exoskeleton 1 2 benik splint* customisable orthosis soft orthosis 1 1 dmo lycra gloves* customisable orthosis soft orthosis 1 1 ergonomic kitchen tools* customised tools singular function 1 1 meta grip cmc splint* customisable orthosis rigid orthotics 1 1 pneuglove powered and actuated device soft exoskeleton 1 0 script active orthosis powered and actuated device rigid exoskeleton 1 0 snu exo-glove powered and actuated device soft exoskeleton 1 0 microstim neuromuscular electrical stimulation emg control 0 1 ness handmaster neuromuscular electrical stimulation manual selection 0 1 note *devices abstracted from text response table 3: main theme and subthemes: opinions and experiences of 13 ahps on assistive devices for hands and wrists. main theme sub-theme mentions (n) defining statement (occupation, country, experience in years) device design function 5 “multifunctional use, patients won’t use it if it helps with only 1[activity]” (ht/ot, 33, usa) * comfort 2 “in my experience, if an ad is not extremely comfortable and easy to use, they usually end up not being used.” (ht/ot, 6, usa) durability 2 “ability of the patient to obtain a replacement or extra items” (ht/ot, 50, usa) weight 1 “if they do not have proximal strength to be able to lift and manipulate the device, what good is it?” (ht/ot, 32, usa) awareness lack of experience 3 “very limited experience unfortunately i could have used more information/experience to treat patients” (ht/ot, 1, usa) lack of knowledge 3 “i am not familiar with the list of adaptive equipment in your international list.” (ht/ot, 43, usa) prescription unclear methods 5 “need for clearly defined way to assess if patient is appropriate for the assistive device” (ht/ot, 40, usa) user adaption 4 “patients are very quick to adapt their movements after an injury, and if they can use the opposite hand, they figure out how to quickly without the need of adapted equipment to assist.” (ht/ot, 6, usa) cost cost efficient alternatives 2 “many times just putting a wrist and hand in a more functional position through static custom splint fabrication can be a low-cost and effective way to address many adl goals.” (ht/ot, 32, usa) https://doi.org/10.33137/cpoj.v7i1.43790 9 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 figure 1: importance of design features based on likert scale responses. table 4: outcome measures and tools ahps have experience using and which they recommend, alongside discrepancies between what is recommended and what has been experienced. outcome measures and tools outcome measures ahps have experience with (n) outcome measures ahps recommend using for hand/wrist assessment (n) difference in recommended tools against experienced range of motion tests 49 43 -6 pain (self-reported) 45 41 -4 disabilities of the arm shoulder and hand questionnaire (dash) 43 38 -5 nine hole peg test (9hpt) 42 30 -12 purdue pegboard test (ppt) 36 15 -21 jebsen-taylor hand function tests (jthft) 28 12 -16 other (please specify) 17 13 -4 ashworth scale 12 6 -6 box and blocks test (bbt) 11 7 -4 motor assessment scale (mas) 5 3 -2 southampton hand assessment procedure (shap) 5 2 -3 force control tests 3 5 2 patient-rated wrist evaluation (prwe)* 3 2 -1 the minnesota manual dexterity test (mrmt)* 3 0 -3 upper extremity functional index* 3 2 -1 fugl-meyer assessment (fma) 2 1 -1 functional dexterity test* 2 2 0 patient rate wrist/hand evaluation (prwhe)* 2 2 0 patient-specific functional scale (psfs)* 2 3 1 quick dash* 2 0 -2 action research arm test (arat) 1 0 -1 corbett targeted coin test* 1 1 0 graded redefined assessment of strength, sensibility and prehension (grassp) 1 0 -1 grooved peg test* 1 1 0 mankoski pain scale* 1 0 -1 modified moberg* 1 0 -1 neck and upper limb index (nuli)* 1 0 -1 pinch/grasp strength* 1 1 0 shoulder pain and disability index (spadi)* 1 0 -1 sollermans* 1 0 -1 the michigan hand outcomes questionnaire (mhq) 1 1 0 thumb disability examination (tdx)* 1 0 -1 timed functional tasks* 1 1 0 wolf motor function test (wmft) 1 0 -1 depends on condition* 0 1 1 note: * outcome measures abstracted from text response https://doi.org/10.33137/cpoj.v7i1.43790 10 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 table 5: main factors limiting ahps from assessing outcomes for patients requiring hand and wrist assistive devices. limiting factors mentions (n) respondents affected by limiting factor (%) time with patients 37 63 lack of equipment 27 45 lack of skills or training 21 35 none* 3 5 cost* 2 3 hygiene protocols* 1 2 inappropriate use* 1 2 note: * factors abstracted from text response discussion principal findings the study aimed to explore barriers and limitations of prescribing actuated assistive devices using a crosssectional survey of allied health professionals. the results indicate that respondents did not recognise nor have experience using state-of-the-art actuated assistive devices, they also had concerns about the design of the devices and methods of prescription. the survey investigated validation methods used by ahps and concerns about the functionality and relevance were prevalent. ahps lacked time with patients, equipment and training to conduct outcome measures for using assistive devices, furthering the barriers for prescribing these devices. 87 responses were collected, with 60 complete responses. these respondents were ahps across the globe from the usa, the uk, switzerland, south africa, nigeria, and ireland. they supported patients with a multitude of conditions, yet these patients were not all suitable for an upper limb actuated device based on current treatment methods. common features of the assistive devices recognised and recommended use a form of electrical stimulation and are distributed in the american marketplace. we can conclude that the us-centric perspective (72% of respondents, 43/60) influenced results, this was noticed in how devices are financed, the reduced importance of the cost of devices, and how financing influences outcome measures. the cost of the devices was considered a less important factor when prescribing an assistive device likely due to the purchasing method of devices. tens and emg devices were expected to be well recognised as they have a long history of use28 compared to the state-of-the-art nature of actuated assistive devices.29 the wealth of evidence to support tens and the large selection of devices easily available for purchase makes it an accessible device for self-funded us citizens. in addition to self-funded citizens, privately funded services would prioritize fda-approved medical devices30 which may reduce the stock of international market options for assistive devices, in turn reducing accessibility. the responses in table 3 address the importance of awareness of new technology, the design of the device, how to prescribe devices and user’s adaption to not requiring a device. as muscle weakness and pain affect people differently, devices must be chosen to best suit the needs of the user. an actuated device may fulfil user’s requirements, but decision-making methods for selecting actuated devices are not readily available. frameworks for selecting assistive technology devices will likely be modified overtime to incorporate actuated devices,31 and the mechanical functionality of these devices varies vastly which makes being aware of all the different styles very difficult. some ahps were unfamiliar with the actuated devices listed in table 2 and suggested they would research on a case-bycase basis for a device, if it would seem useful for a patient. the process of researching and prescribing a device uniquely for a patient is an appropriate method, but time with patients is a considerable barrier (table 5 and table 6). onetime visits are a considerable limitation for supporting potential assistive device users, especially if aiming to use table 6: main themes: opinions and experiences of 29 ahps on outcome measures for hands and wrists. theme defining statement (occupation, country, experience in years) mentions (n) functionality “basic self-reported outcome measures like quickdash don't distinguish one hand vs two for the activities.” (ht, usa, 42)* 20 relevance “outcome measures are important to demonstrate that what we are doing in therapy is being effective. i have yet to find one that is really good. we use the quick dash because our physicians use it” (ht/ot, usa, 40) 15 documentation “we need a standardised assessment to help compare between patients but also document a patient's own journey” (orthotist, uk, 12) 9 time “if we are seeing them for a one-time visit (more and more common in the us), then where is the time for an outcome study?” (ht/ot, usa, 32) 6 inclusiveness “every patient is unique in their injury and their needs, and outcome measurements should better accommodate for this.” (ht/ot, usa, 6) 5 financing “useful if funding source understands the assessment. i usually document the rational of the measure for the funding source and try to compare the patient's abilities with individuals without the problem.” (ht/ot, usa, 50) 4 *(occupation, country, and experience in years) https://doi.org/10.33137/cpoj.v7i1.43790 11 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 outcome measures as quoted in table 6. this poses an additional constraint to documenting a patient’s improvements and any comparison of their functionality with a baseline. as time is an obstacle for both assessing a user's functionality and researching which device would be useful, it is important to understand how to reduce time spent on these tasks. outcome measures were used to assess patient’s needs, yet thematic analysis (table 6) showed that the outcome measures used in the workplace did not capture the patient’s functionality. there is an immense list of outcome measures available, but decision-making varied in the demographic groups. some ahps chose relevant validation methods whereas some were decided for them by funding sources. therefore, depending on how much time the ahp had with a patient, finding a relevant outcome measure that checks user functionality is a barrier. in addition, the patient may only have a one-time visit therefore the process of assessing how well the assistive device functions for the user does not get recorded and limits clinical evidence available for their use. to reduce these limitations, 3 suggestions could be investigated for future research: 1) develop a decisionmaking tool to help ahps select appropriate outcome measures based on the available time and equipment; 2) adapt existing, well-established outcome measures to enhance their relevance; or 3) provide patients with a quantitative, longitudinal outcome measure tool to track their functionality and experiences with the actuated device. the limitations in using outcome measures focused on lack of time, equipment and training. these barriers are reflected in literature in the fields of physical therapy,32 hand therapy33 and ahps.34 to see if this was reflected in the outcome measures, table 7 shows that the more commonly used outcome measures do not take a considerable time to complete (average 14 minutes), nor require complex equipment. however, table 7 assumes the outcome measurement tools are set up and only one test is conducted per visit which is unrealistic. the potential contrasting views on the limitations of outcome measures (table 5 and table 6) and the ones used in the workplace (table 7) were not questioned as part of the survey, therefore, it is hard to distinguish the source of the contrast. but a reoccurring theme for those who used outcome measures was that when time, equipment and training were not a limitation, the outcome measurement tools chosen were still often irrelevant and did not adequately assess users' functionality. limitations this cross-sectional study has several limitations to consider. due to the methodology, self-reported data and table 7: a breakdown of the top ten most experienced outcome measures shown in table 4: equipment, cost, time and skill required to complete. outcome measures and tools equipment cost (£, $) time (minutes) skill level* references range of motion tests goniometer and inclinometer £15, $5$100 10 medium 35,36 pain (self-reported) paper or screen 0 10 low 37,38 dash paper or screen 0 5-10 low 39-41 9hpt 9-hole peg test kit and stopwatch £9.99-£75, $84 5 low 42,43 ppt purdue pegboard and stopwatch £200, $150 5-10 low 44,45 jthft test kit (stopwatch, chair, table, paper, clipboard, cards, coffee can, paperclips, beans, spoon, board, clamp, red wooden checkers, cans) £335, $300$500 30 medium 46,47 ashworth scale paper or screen 0 15 medium 48 bbt wooden box, wooden cubes, partition stopwatch £250, $200 5-10 low 49,50 mas test kit (stopwatch, jellybeans, cup, rubber ball, stool, comb, spoon, pen, teacups, water, jar, table) estimated £58.8, $77 15 medium 51,52 shap test kit (backboard, door handle and zip, shape form-board, foam insert, timer unit, lightweight abstract objects, heavyweight abstract objects, lock and key, zip, coins, buttons, plasticine block, knife, notecard, glass jar with lid, glass jug, cardboard juice carton, empty tin with plastic lid, metal arrow unit, screwdriver) £2150, $2833 20 medium 53 note: *skill level is assumed low if data collected is observational https://doi.org/10.33137/cpoj.v7i1.43790 12 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 convenience sampling may lead to overgeneralization of results. the sample was not fully representative of all upper limb assistive device prescribers and assessors. however, this limitation highlights the barriers to prescribing and assessing these devices faced by our participants, which warrants further investigation with more stakeholders. despite international dissemination, there was a high percentage of american participants, limiting comparisons with other countries. this was partly due to the larger size of the asht mailing list (7,000+ members) compared to other associations (<3,000 members). the us-centric perspective did reveal how financing influences the assistive technology marketplace and outcome measure decisions. this underscores the need for future research to include surveys of non-ahp stakeholders, such as users, manufacturers, and policymakers. the survey questions, which incorporated previous literature for curating lists and validated methods like quest 2.0 for design factors of importance, may have lacked flexibility and potentially influenced respondents. however, text fields were provided for additional responses, and results showed that these factors did not significantly influence responses, particularly regarding actuated devices which had low levels of recognisability. despite these limitations, our study identifies factors influencing the prescription and validation of actuated upper limb devices. future research could address improving the stakeholder representation and should tailor the methodology and questions to be more inclusive of factors missed within this study. conclusion a cross-sectional survey quantifying ahps perspectives on assistive devices and outcome measures was conducted. we identified important factors for prescribing an actuated device. these factors include design requirements, awareness of devices and decision-making support. the population who responded to our survey found many assistive devices to be uncomfortable for users, too heavy, not versatile enough and that users would adapt to not needing one. for an actuated device the weight, cost of the device, mechanical power and portability were considered not as important as other design features. results showed this may be due to the respondents’ lack of exposure to actuated assistive devices and unclear methods to prescribe a relevant device. in addition, for this group of ahps, their patient population may not find an actuated device functional or relevant. our study also shows that outcome measures were rarely used to assess assistive devices, which means their clinical evidence will not increase to improve market exposure. conducting outcome measures for patients faced many limitations. ahps found these tools useful, but due to time constraints, and lack of equipment and training, they were not used regularly. respondents wanted to use these tools to track the user's functionality, but patients may only attend a one-time visit. to better support ahps, decision-making tools, training and modifying outcome measures would be appropriate. increasing the market presence of actuated devices would also increase stakeholder engagement. in the future, researchers should use validation methods that tackle wearability, comfort, user satisfaction, safety and ease of use of their device. these validation methods should encompass observational outcomes used in clinical settings and users' perspectives. acknowledgements we would like to acknowledge the funding and support from the university of strathclyde and the uk engineering and physical sciences research council (ep /s02249x). declaration of conflicting interests the authors declare no conflict of interest. authors contribution angel galbert: study conception and design, data collection, analysis and interpretation of results, draft manuscript preparation, and manuscript revision. arjan buis: supervision, study conception and design, and manuscript revision all authors have read and approved the final submitted manuscript. sources of support esprc doctoral training grant (ep/s02249x/) references 1.eraifej j, clark w, france b, desando s, moore d. effectiveness of upper limb functional electrical stimulation after stroke for the improvement of activities of daily living and motor function: a systematic review and meta-analysis. syst rev. 2017; 6:1-21. doi: 10.1186/s13643-017-0435-5 2.mercier l, audet t, hébert r, rochette a, dubois m-f. impact of motor, cognitive, and perceptual disorders on ability to perform activities 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orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 appendix survey flow ▪ permissions (2 questions) ▪ demographics (5 questions) ▪ assistive devices (10 questions) ▪ outcome measures (8 questions) ▪ permissions q1: participant information sheet name of department: biomedical engineering title of the study: analysis of current hand and wrist assistive devices, and requirements for a future device introduction my name is angel galbert, and i am a phd student within the department of biomedical engineering at the university of strathclyde, glasgow, united kingdom. i am undertaking this study as part of my research in hand and wrist assistive devices. i am conducting xxxxx research under the supervision of chief investigator – arjan buis, department of biomedical engineering. what is the purpose of this research? according to the national institute for health and care excellence (nice), the population of those affected by muscle weakness in the hands and wrist continues to grow. conditions such as stroke, spinal cord injury paralysis, parkinson’s disease and cerebral palsy have shown to affect the hand and wrist ability to function in activities of daily living and therefore reduce quality of life. assistive devices are being incorporated in the retraining and recovery for some of these conditions, but rehabilitation treatment and assistance may be required outside of a clinical setting. assistive devices may also provide additional strength, function and prehension to users wanting independence and support. previous studies have designed assistive devices that can be used in everyday life in the form of exoskeletons and powered orthoses. these devices show mechanical potential but lack clinical outcome measures when testing. the lack of clinical outcome measures makes it difficult to assess usability. it also makes assistive devices difficult to compare for decision making when prescribing. this research aims to determine the requirements for an assistive device for use in everyday living by gathering opinions on current devices, user needs and outcome measures. this research will provide the foundations for designing a device with a user-centred approach. do you have to take part? no. you do not have to take part as participation is voluntary. if you do not wish to take part in the study, there is no consequences of doing so. you have the right to withdraw from the research without detriment. what will you do in the project? you will begin by following a link to the survey. the consent form is on the first page of the survey. please answer the questions on the consent form to confirm that you understand. if you give consent to take part in the study, you will click the button to continue and will be directed on to the survey questions. if you decline to give consent, you will be able to navigate out of the survey. the survey includes questions about your background, experience with hand and wrist assistive devices and upper limb outcome measures. you will also be invited to share your general thoughts on hand and wrist assistive devices. the survey should take no longer than 15 minutes to complete. the screen will state “thank you for completing the survey” to mark the end of the survey and confirm that your responses have been saved. the survey will be live until december 4th, 2023, and you will be able to take the survey at any point within this period. no monetary incentive will be provided for taking part in the survey. as the survey is online, there are no expenses associated with travel costs. who should take part? we are looking for participants who work or have worked with persons with muscle weakness in the hands and wrist. you should have experience of this work within the past 5 years. this may include, but is not limited to, hand therapists, orthotists, prosthetists, occupational therapists, physiotherapists, personal trainer, rehab specialist, assistive technology consultant, medical sales representative, engineers, nurses, doctors, or surgeons. participants must be able to read and comprehend english. what information is being collected in the project? information collected includes your experience with hand and/or wrist assistive devices, your experience with upper limb outcome measures, and opinion on requirements for an assistive device. none of the information collected will be identifiable. who will have access to the information? the study is conducted in lines with the university general data protection regulation (gdpr) policy. the university privacy https://doi.org/10.33137/cpoj.v7i1.43790 16 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 notice can be found online on the following website: https://www.strath.ac.uk/research/researchknowledgeexchangeservices/universityethicscommittee/informationsheetconsentform/ information that you provide will remain confidential. all data will be stored on a secure platform accessed only by the investigators. only non-identifiable information will be used when findings from the study are shared. where will the information be stored and how long will it be kept for? data obtained from this study will be stored on the university’s secure platform and accessed only by named researchers. access and destruction of the data will be according to the university of strathclyde data protection policy and gdpr. as the data is anonymous, the consent form and anonymous data may be kept indefinitely. what happens next? thank you for your attention and time reading the participant information. if you would like to find out more about the project or wish to ask questions before participation, please contact the researchers. your responses to the survey will be anonymous. the results of this study will be reported in the researcher’s (angel galbert) phd thesis and may be published in other academic papers, presentations and/or conferences. as the survey is anonymous, the identities of the participants are unknown to investigators and will therefore not be published. researcher contact details: angel galbert, phd student department of biomedical engineering, university of strathclyde. email: angel.galbert@strath.ac.uk chief investigator details: arjan buis, reader department of biomedical engineering, university of strathclyde. email: arjan.buis@strath.ac.uk this research was granted ethical approval by the department of biomedical engineering ethics committee, university of strathclyde. if you have any questions/concerns, during or after the research, or wish to contact an independent person to whom any questions may be directed or further information may be sought from, please contact: linda gilmour secretary to the departmental ethics committee, department of biomedical engineering, university of strathclyde. tel: 0141 548 3298 email: linda.gilmour@strath.ac.uk o i confirm i have read the participant information sheet (1) q2: consent form please read of the following statements and check the box below to confirm: i confirm that i have read and understood the participant information sheet for the above project and the researcher has answered any queries to my satisfaction. i confirm that i have read and understood the privacy notice for participants in research projects (https://www.strath.ac.uk/research/researchknowledgeexchangeservices/universityethicscommittee/informationsheetconsentform/) and understand how my personal information will be used and what will happen to it (i.e. how it will be stored and for how long). i understand that my participation is voluntary and that i am free to withdraw from the project at any time, up to the point of completion, without having to give a reason and without any consequences. i understand that anonymised data (i.e. data that do not identify me personally) cannot be withdrawn once they have been included in the study. i understand that any information recorded in the research will remain confidential and no information that identifies me will be made publicly available. o yes. i consent to being a participant in the project. (1) o no. i do not consent to being a participant in the project. (2) skip to: end of survey if q2 = no. i do not consent to being a participant in the project. a p p e n d ix https://doi.org/10.33137/cpoj.v7i1.43790 https://www.strath.ac.uk/research/researchknowledgeexchangeservices/universityethicscommittee/informationsheetconsentform/ mailto:angel.galbert@strath.ac.uk mailto:arjan.buis@strath.ac.uk mailto:linda.gilmour@strath.ac.uk 17 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 ▪ demographics q3: what is your occupation? o assistive technology consultant (1) o hand therapist (2) o health care assistant (hca) (3) o medical doctor (4) o nurse specialist (5) o occupational therapist (6) o orthotist (7) o physiotherapist (8) o prosthetist (9) o rehabilitation specialist (10) o other (please specify) (11) q4: have you worked in this field within the last 5 years? o yes (1) o no (2) skip to: end of survey if q4 = no q5: how long have you worked in this occupation? (please provide answer in years) q6: in which country do you currently work? q7: which patient population(s) do you interact with? o carpal tunnel syndrome (1) o cerebral palsy (2) o duchenne muscular dystrophy (3) o epicondylitis (4) o multiple sclerosis (5) o parkinson's disease (6) o peripheral neuropathy (7) o sarcopenia (8) o spinal cord injury (9) o stroke (10) o other (please specify) (11) __________________________________________________ ▪ assistive devices q8: do you prescribe assistive devices for hands and wrists? o yes (1) o no (2) q9: do you assess assistive devices for hands and wrists? o yes (1) o no (2) a p p e n d ix https://doi.org/10.33137/cpoj.v7i1.43790 18 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 q10: which assistive device(s) have you heard of? o armmotus (1) o dtsam orthosis (2) o exotic exoskeleton (3) o fesia grasp device (4) o gloreha lite glove (5) o graspyglove (6) o hand of hope (7) o handy rehab (8) o intfes (9) o jaco (10) o mahi exo (11) o mecfes (12) o microstim (13) o myopro orthosis (14) o ness handmaster (15) o odstock (16) o pneuglove (17) o rehand (18) o rein-hand system (19) o rupert (20) o saebomas (21) o script active orthosis (22) o sem glove (23) o snu exo-glove (24) o tenoexo hand exoskeleton (25) o tens stimulator (26) o tiger (27) o x-glove (28) o none (29) o other (please specify) (30) ______________________________________________ display this question: if q8 = yes q11: which assistive device(s) have you worked with? o armmotus (1) o dtsam orthosis (2) o exotic exoskeleton (3) o fesia grasp device (4) o gloreha lite glove (5) o graspyglove (6) o hand of hope (7) o handy rehab (8) o intfes (9) o jaco (10) o mahi exo (11) o mecfes (12) o microstim (13) o myopro orthosis (14) o ness handmaster (15) o odstock (16) o pneuglove (17) o rehand (18) o rein-hand system (19) o rupert (20) o saebomas (21) o script active orthosis (22) o sem glove (23) o snu exo-glove (24) o tenoexo hand exoskeleton (25) o tens stimulator (26) o tiger (27) a p p e n d ix https://doi.org/10.33137/cpoj.v7i1.43790 19 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 o x-glove (28) o other (please specify) (29) __________________________________________________ display this question: if q8 = no q12: do you offer assistive devices for hands and wrists in your workplace? o yes (1) o no (2) display this question: if q12 = yes q13: which assistive device(s) are offered in your workplace? o armmotus (1) o dtsam orthosis (2) o exotic exoskeleton (3) o fesia grasp device (4) o gloreha lite glove (5) o graspyglove (6) o hand of hope (7) o handy rehab (8) o intfes (9) o jaco (10) o mahi exo (11) o mecfes (12) o microstim (13) o myopro orthosis (14) o ness handmaster (15) o odstock (16) o pneuglove (17) o rehand (18) o rein-hand system (19) o rupert (20) o saebomas (21) o script active orthosis (22) o sem glove (23) o snu exo-glove (24) o tenoexo hand exoskeleton (25) o tens stimulator (26) o tiger (27) o x-glove (28) o other (please specify) (29) __________________________________________________ display this question: if q12 = no q14: why not? q15: do you feel you have enough access to assistive devices for hands and wrists? o definitely yes (1) o probably yes (2) o may or may not (3) o probably not (4) o definitely not (5) a p p e n d ix https://doi.org/10.33137/cpoj.v7i1.43790 20 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 display this question: if q8 = yes or q9 = yes or q12 = yes q16: in your opinion, which factors are most important when assessing an assistive device? not at all important (1) slightly important (2) moderately important (3) very important (4) extremely important (5) cost of device (1) ease of use (2) mechanical power (3) portability (4) safety (5) user satisfaction (6) wearability and comfort (7) weight (8) q17: please add any additional comments about your opinions and experiences of assistive devices for hands and wrists ▪ outcome measures q18: do you have experience using outcome measures for upper limb assessment? o yes (1) o some experience (2) o no (3) display this question: if q18!= no q19: which outcome measure(s) do you have experience with? o action research arm test (arat) (1) o ashworth scale (2) o box and blocks test (bbt) (3) o disabilities of the arm shoulder and hand questionnaire (dash) (4) o force control tests (5) o fugl-meyer assessment (fma) (6) o graded redefined assessment of strength, sensibility and prehension (grassp) (7) o jebsen-taylor hand function tests (jthft) (8) o motor activity log (mal) (9) o motor assessment scale (mas) (10) o nine hole peg test (9hpt) (11) o pain (self-reported) (12) o purdue pegboard test (ppt) (13) o range of motion tests (14) o southampton hand assessment procedure (shap) (15) o wolf motor function test (wmft) (16) o other (please specify) (17) _______________________________________________ a p p e n d ix https://doi.org/10.33137/cpoj.v7i1.43790 21 galbert a, buis a. exploring factors for prescription and validation of actuated upper limb devices: a cross-sectional survey of allied health professionals. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.4. https://doi.org/10.33137/cpoj.v7i1.43790 canadian prosthetics & orthotics journal issn: 2561-987x factors in prescribing actuated upper limb devices: a survey of allied health professionals galbert a, and buis a, 2024 display this question: if q18!= no q20: which outcome measure(s) do you recommend using for hand and/or wrist assessment? o action research arm test (arat) (1) o ashworth scale (2) o box and blocks test (bbt) (3) o disabilities of the arm shoulder and hand questionnaire (dash) (4) o force control tests (5) o fugl-meyer assessment (fma) (6) o graded redefined assessment of strength, sensibility and prehension (grassp) (7) o jebsen-taylor hand function tests (jthft) (8) o motor activity log (mal) (9) o motor assessment scale (mas) (10) o nine hole peg test (9hpt) (11) o pain (self-reported) (12) o purdue pegboard test (ppt) (13) o range of motion tests (14) o southampton hand assessment procedure (shap) (15) o wolf motor function test (wmft) (16) o none (17) o other (please specify) (18) q21: what do you feel are the main limitations to assessing outcomes for patients requiring hand and wrist assistive devices? o time with patients (1) o lack of skills or training (2) o lack of equipment (3) o other (please explain) (4) __________________________________________________ q22: in your opinion, are outcome measurement tools useful for patients requiring assistive devices? o yes (1) o unsure (2) o no (3) q23: in your opinion, could outcome measurement tools be improved for patients requiring assistive devices? o yes (1) o unsure (2) o no (3) display this question: if q23 = yes q24: please give a short explanation as to why/how outcome measures could be improved for assessing assistive devices for hands and wrists q25: please add any additional comments about your opinions and experiences with outcome measures a p p e n d ix https://doi.org/10.33137/cpoj.v7i1.43790 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 1 2025 research article visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/cpoj.v8i1.45286 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i1.45286 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/cpoj.v8i1.45286 research article south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study visagie s1*, theron b2 1. university of stellenbosch, division of disability and rehabilitation studies, faculty of medicine and health sciences, south africa. 2. össur south africa, cape town, south africa. introduction persons with amputations expressed the notion that prostheses “normalize” their functionality and physical appearance.1,2 over the years, prosthetic development has aimed to enhance this sense of “normalization” and minimize functional loss, benefiting from advanced materials and the integration of software technologies. an example is the use of sensors and microprocessorcontrolled software in prosthetic knee and ankle components.3 microprocessor knees (mpks) provide high levels of safety, consistency, and confidence during walking.3 one of the most widely recognized benefits of mpks is their ability to reduce stumbles and falls.4 research has also shown improved physiological functions such as a decrease in oxygen cost when walking with mpks compared to nonmicroprocessor knees (nmpks).5 mpks enhance walking speed, stair climbing, hill descent, walking on uneven terrain, and the ability to multitask while walking.5 however, mpks are expensive, with prices starting at over r600,000 (us$32,000) and reaching up to r1 million (us$55,000). open access abstract background: microprocessor knees (mpks) support safe and confident prosthetic walking. their cost often prohibits prescription in low-and middleincome settings like south africa. funding of high-end prosthetic products in south africa is dependent on justifications that explain why the component is prescribed, and how it can improve the user`s function. there is little local evidence to support these justifications. objective: to explore and describe south african users’ function and experience with the rheo xc microprocessor knee (mpk). methodology: an explanatory sequential mixed methods design was used. a pre-test, post-test study was followed by a descriptive qualitative study to explore and explain the observed outcomes. in the pre-test phase, baseline data were collected while participants used their regular non-microprocessor knees (e.g., mechanical or hydraulic joints). post-test data were collected after a two-week trial with the rheo xc knee joint. data were collected from 16 consecutively sampled participants, using a self-developed functional level scale and the l-test. nine (56.3%) participants had a transfemoral amputation, six (37.5%) had a knee disarticulation and one (6.3%) had bilateral amputations (transtibial and transfemoral). baseline and follow-up data were paired for each participant and analyzed with the wilcoxon signed-rank test. the descriptive qualitative study explored six purposively sampled participants’ experiences of the trial knee through semi-structured interviews. inductive thematic analysis was done. findings: the time to complete the l-test decreased on average 7.5 s between baseline (35.4 s) and post-test (27.9 s) data. l-test wilcoxon singed-rank findings showed a significant increase in walking speed (p < 0.001). mean functional level scores increased by an average of 12.7 points (p < 0.001) with improvements observed across all activities except running, for which scores remained unchanged. two themes emerged from the qualitative data. theme 1: acceptance of the mpk showed enthusiasm for the mpk. however, theme 2: realworld limitations of the mpk cautioned that the mpk is not suitable for everybody. conclusion: this study provides context specific scientific evidence that may support funding decisions for mpks in south africa. however, it is not suitable for everyone, and a trial period to assess appropriateness is advised before prescription. the test period in this study was short, and further research over longer durations is recommended. article info received: april 29, 2025 accepted: june 6, 2025 published: june 12, 2025 citation visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/c poj.v8i1.45286 keywords amputation; south africa; lower middle-income countries; prosthetic prescription; rheo xc; transfemoral; transtibial; rehabilitation; l-test; microprocessor knee; knee disarticulation; mpks. * corresponding author: surona visagie, phd affiliation: university of stellenbosch, division of disability and rehabilitation studies, faculty of medicine and health sciences, south africa. e-mail: suronav@sun.ac.za orcid id: https://orcid.org/0000-0003-4575-479x journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 1, article no. 5. 2025 https://doi.org/10.33137/cpoj.v8i1.45286 https://doi.org/10.33137/cpoj.v8i1.45286 https://doi.org/10.33137/cpoj.v8i1.45286 mailto:suronav@sun.ac.za https://orcid.org/0000-0003-4575-479x https://jps.library.utoronto.ca/index.php/cpoj/index 2 visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/cpoj.v8i1.45286 canadian prosthetics & orthotics journal issn: 2561-987x magnetorheological knee use in south africa: function and experience visagie s and theron b, 2025 even though research shows that future savings and financial benefits might offset the initial high cost of the mpk6,7 the expense remains a barrier to prescription. provision of prosthetic components—whether costly or not—is hampered by a shortage of financial resources, poor social security systems, and little health insurance in lowand middleincome countries (lmics).8,9 service-related factors such as limited access to equipment and materials, limited numbers of adequately trained prosthetists, clustering of prosthetic services in metropoles and bureaucratic red tape further obstructs prosthetic services.8-13 there is also limited awareness of services, service pathways, and device options among users.8,9,14 geographical challenges, large rural areas, inadequate transport systems, and poor infrastructure further decrease access to prosthetic devices.8,10,14-16 finally, prosthetic components dependent on computer software such as mpks are sometimes considered too fragile for the harsh environments and employment requirements in lmics.10 therefore, context specific research is required to ensure that products which has shown superior function in global north settings are appropriate for use in the lmics.10,14 the only statistics currently available on the need for prosthetics in south africa comes from the 2022 national census which states that there are around 430,000 upper and lower limb prosthetic users in the country.17 waiting periods9,15,16,18 and waitlists for prostheses19 are long. in addition, while a prosthesis is often promised at the time of amputation20 receiving one is not a given.21,22 for those who do receive a prosthesis, functional ability is often not optimally supported by the componentry provided in both the private9 and public sectors.15 in the south african private sector, the funding of high-end prosthetic products, including mpks, is dependent on special justifications explaining the functional benefits of the more expensive component, and lengthy waiting periods before authorization for the components are received.9 mpks are seldom covered by medical insurance, but are provided through the road accident fund.9 in the public sector, which provides the bulk of prosthetic services in the country and will play an even larger role after the implementation of the national health insurance act, highend products are not currently funded.15 prosthetic component selection is based on empirical knowledge and financial considerations rather than evidence-based guidelines in both the government and private sectors. inconsistencies, over, and under prescription, which are at least in part due to insufficient local evidence, are real concerns.9 therefore, the aim of the study was to explore and describe users’ function and experience with an mpk, the rheo xc, which generates knee joint resistance through a magnetorheological clutch mechanism23 in comparison to the nmpks participants normally use in south africa. it is hoped that the results will contribute to the evidence base for prosthetic practice in south africa. the study focused on a specific microprocessor knee (mpk) because, although mpks are similar in type, they differ in the specific functional features they provide.24 methodology to ensure robustness and rigor, an explanatory sequential mixed methods design was employed. changes in user function were determined using a quantitative pre-test, posttest design. functional changes were contextualized and further explored with a qualitative descriptive study. the results were analyzed separately and triangulated in the discussion.25 pre-test, post-test sixteen consecutively sampled prosthetic users were included in the pre-test, post-test study. they had to: • be older than 18 (age of majority in south africa) • have a transfemoral amputation or knee disarticulation • have an amputee activity level of k2-k4 on the amppro.26 • use a prosthesis for more than four months to ensure sufficient adaptation to the prosthesis.27 users who did not complete the two-week trial period or who experienced a health crisis such as a stroke that might influence their functioning, during the two weeks, would have been excluded. however, these situations did not occur. four users who started the trial did not complete the study (one had a faulty mpk and the other three did not complete the post-test). baseline and follow up data on functioning and walking speed with the participant`s conventional knee and the rheo xc were collected between 01 march 2023 to 31 january 2025. the pre-test was completed before the rheo xc was fitted, and post-test data were collected two weeks after fitting the device. history, maturation, cognitive learning, interrater reliability, statistical regression, and sensitization all pose threats to the internal and external validity of the pre-test, post-test design.28 these challenges of one group designs are acknowledged. however, in this study, with its short time frame and contained independent variable (i.e. a different knee component), many of these concerns were mitigated. external changes should not influence the function with the knee because the physical environment in which the user operated remained the same. to prevent maturation effects, users had to have been walking with a prosthesis for four months or more at the time of the pre-test. function is physical in nature; thus, cognitive learning was not a concern. spontaneous remission does not pose a risk to validity as an amputation is a permanent impairment. factors such as interest level, and general fatigue could not be controlled and might have influenced scores. clinical https://doi.org/10.33137/cpoj.v8i1.45286 3 visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/cpoj.v8i1.45286 canadian prosthetics & orthotics journal issn: 2561-987x magnetorheological knee use in south africa: function and experience visagie s and theron b, 2025 evaluation commonly involves pre-test, post-test assessments.29 thus, this design was deemed suitable for the current study with its focus on clinical application. in addition, results were verified through triangulation with qualitative descriptive findings. the supplier of the rheo xc, össur, offers trial periods with the knee to users in south africa (this service has been offered for years; it was not started with the current study in mind). the current study utilized data collected during this trial period. prosthetists request trial units for users based on the user’s function and physical ability. during the study period, the prosthetist was informed about the research only after a trial request for the mpk knee being studied was received. they were asked to provide users with the information leaflet and informed consent form, and to obtain written consent from those willing to participate in the study. participation was voluntary, and the informed consent form emphasized that the decision to participate was entirely up to the user. the decision did not affect access to a trial mpk, or any other service provided to them by the company or prosthetist. all users who trialed the mpk during the study period were approached consecutively to participate in the study. twenty agreed to participate, of whom 16 completed the study. the number of users who requested a trial period and who were approached to participate is unfortunately not known. this omission and the small sample size reduced internal validity and generalizability of the findings. data were collected using a functional level scale and the l-test of functional mobility (l-test). the functional level scale was developed though combining the trinity amputation and prosthesis experience scales – revised (tapes-r),30 the locomotor capabilities index-5 (lmci5)31 and the prosthetic limb users survey of mobility (plus-m).32 these scales assess slightly different functional aspects and through combining them a comprehensive picture of changes in functional ability could be obtained. all three of these scales are valid and reliable.30-32 however, the combination used in this study was not tested for reliability and validity. this is a limitation that can negatively affect the study’s reliability and external validity. questions focused on indoor and outdoor mobility, as well as participation in community, sport, and work activities. scoring was based on a five-point likert scale, with total scores ranging from 20 to 80. higher scores indicated better function. the l-test is a simple and quick mobility test. it measures the time to get up from a chair (seat height 46 cm), walk 3 meters, turn 90o, walk 7 meters, turn 180o, and walk back to the chair in seconds.33 the l-test has shown high levels of interand intra-rater reliability (0.97 and 0.97 respectively) as well as concurrent validity.33 it also has a low ceiling effect in higher functioning prostheses users.33 prosthetists measured the l-test times with a smart phone stopwatch. in addition, data on demographic variables, amputation details, and the prosthetic components habitually used were collected and coded. items that were scored as “not applicable” were removed from the preand post-test scores for that specific participant. descriptive analysis was done after which the wilcoxon signed-rank test was used to evaluate for significant differences in function and l-test scores between matched pairs. qualitative descriptive study during an iterative process, six prosthetic users who had completed the trial period were purposively sampled using a maximum variation strategy.34 variables used to ensure maximum variation included gender, age, level of amputation, k-level, differences in l-test and functional level scores. data were collected with a 30-minute audio recorded, telephonic, semi-structured interview. interviews were guided by an interview schedule developed by the authors. questions focused on the participants’ opinion of the rheo xc and their thoughts on why their function and l-test scores were different or similar in the preand posttest. inductive thematic analysis was done.35 the first author identified codes (meaningful parts, ideas, and key concepts in the data), through line-by-line coding, and provisional themes manually, as interviews were completed. provisional themes and questions raised by the analysis informed further sampling, data collection and analysis. data saturation was reached after the 6th interview. codes and themes were finalized and verified by the second author. trustworthiness is supported by purposive sampling, using an interview schedule, data saturation, a second person verifying themes and describing participants’ demographic details. an additional limitation of the study is the absence of independent coding and consensus-building between the two authors, which would have enhanced trustworthiness. publication ethics the study was approved by stellenbosch university’s health research ethics committee (n22/08/097). the risk for physical harm during the test period was very low since the participants had been walking with the prosthesis for at least four months and had a minimum ability to walk in the community on level surfaces as per inclusion criteria. results quantitative of the 20 participants who agreed to take part, 16 completed the study, of whom 13 (81.25%) were men. nine (56.25%) had transfemoral amputations and functioned at a k3 level (table 1). for four participants with knee disarticulation, a low-profile foot was required to accommodate the length of the rheo xc knee. the reasons for the foot changes in the other two cases were unclear. these changes negatively affect the internal validity of the study. https://doi.org/10.33137/cpoj.v8i1.45286 4 visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/cpoj.v8i1.45286 canadian prosthetics & orthotics journal issn: 2561-987x magnetorheological knee use in south africa: function and experience visagie s and theron b, 2025 table 1: demographic and amputation related information of participants (n=16). no. (%) gender men 13 (81.3) women 3 (18.8) cause of amputation vascular 3 (18.8) trauma 11 (68.8) cancer 1 (6.3) congenital 1 (6.3) level of amputation transfemoral 9 (56.3) knee disarticulation 6 (37.5) bilateral (tf & tt) 1 (6.3) k-level k2 2 (12.5) k3 9 (56.3) k4 5 (31.3) pre-test no. (%) post-test prosthetic knees paso knee (ossur) 4 (25.0) rheo xc 3r31 (otto bock) 1 (6.3) 3r106 (otto bock) 2 (12.5) 3r80 (otto bock) 3 (18.8) 3r95 (otto bock) 1 (6.3) 3r78 (otto bock) 1 (6.3) ohp5 (ossur) 1 (6.3) aspire h1 (ossur) 1 (6.3) balance knee (ossur) 1 (6.3) total 2100 (ossur) 1 (6.3) prosthetic feet vari-flex (ossur) 5 (31.3) unchanged triton (otto bock) 1 (6.3) changed to pro-flex lp balance j (ossur) 1 (6.3) changed to breeze (steeper) trias (otto bock) 2 (12.5) changed to pro-flex lp taleo (otto bock) 1 (6.3) unchanged 1d10 (otto bock) 1 (6.3) unchanged sach (otto bock) 1 (6.3) changed to pro-flex st dp flexion (ossur) 1 (6.3) changed to pro-flex st pro-flex st (ossur) 1 (6.3) unchanged triton sideflex (otto bock) 1 (6.3) unchanged breeze (college park) 1 (6.3) unchanged table 2: descriptive summary of age, pre-test, post-test, l-test and function scores. low high mean (sd) cohen’s d z value pvalue age 26 74 51.9 (14.9) pre-test l-test (s) 17.5 71.0 35.4 (16.4) 0.52 -3.52 0.00 post-test l-test (s) 14.0 62.2 27.9 (12.3) pre-test function* 31 76 52.7 (12.2) 1.22 -3.41 0.00 post-test function* 49 78 65.4 (8.3) *higher scores indicate better function. their average age was 51.9 (sd = 14.9) ranging from 26 to 74 (table 2). participants completed the l-test on average 7.5 s faster in the post-test than in the pre-test. the mean function score was 12.7 higher in the post-test than the pretest (table 2). l-test scores were consistently lower in the post-test indicating faster walking and turning speeds with the rheo xc (figure 1). this difference varied from 0.3 s to 20.9 s. the wilcoxon signed-rank test of matched l-test data showed a z-value of -3.52 and p < 0.001. figure 1: l-test times before and after the intervention. figure 2: functional scores before and after the intervention. figure 2 shows improved function with the rheo xc. the wilcoxon-signedrank test found a z value of -3.41 with p < 0.001. higher scores indicate better function. all but one activity (running, which remained the same) scored higher in the post-test than the pre-test (figure 3). the variables of work (18 points), walk 100 m (15 points), carry shopping, walking hills, walking in mud /dust (14 points), hiking, and walking on uneven outdoor surfaces (13 points) showed the biggest positive change. all participants indicated that it would be easy to charge the battery. qualitative among the six participants one was a woman, and one had an amputation due to vascular reasons. their age ranged between 26 and 74. l-test speed differences ranged from 0.2 s to 19.3 s. the differences in functional scores ranged between 2 and 16 (table 3). 0 10 20 30 40 50 60 70 80 t im e i n s e c o n d s participants pre test post test 0 10 20 30 40 50 60 70 80 s c o re s pre test post test participants https://doi.org/10.33137/cpoj.v8i1.45286 5 visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/cpoj.v8i1.45286 canadian prosthetics & orthotics journal issn: 2561-987x magnetorheological knee use in south africa: function and experience visagie s and theron b, 2025 participants were enthusiastic about the rheo xc, as illustrated by theme 1: acceptance of the mpk. however, concerns were raised as well, indicating that mpk is not suitable for everybody, as explained in theme 2: real-world limitations of the mpk. theme 1: acceptance of the mpk participants found the rheo xc safe, easy to walk with, and responsive to their mobility needs. “it was immediately comfortable. i felt safe. the knee became my own, in other words, like my living knee. that was what it felt like. the quick responses…i liked it. it is an absolute pleasure to put it on. the control of the knee gives you many options. you can walk faster with confidence. the knee gives that to you, the confidence….i did not want to give it back!” p6 participant 1 felt that the rheo xc joint allowed a more natural walking pattern which he thought led to an increase in walking speed. “it mimics natural walking…it is definitely a more natural walking pattern, which result in me being able to walk faster. even turning on my left leg [prosthetic side] was very natural.” p1 the quick response of the joint to changes in walking speed and/or direction aided a normal walking pattern. “i can move faster. i can turn easier. it is easier to pick up stuff, especially large items. on uneven ground, much safer, sturdy. you are so confident. you can walk like you want to. you do not have to worry about stepping on a pebble, or a clump of grass. you walk; this is just fantastic.” p4 even though participant 2’s l-test results showed only a 0.2 second difference (between preand post-test data), he was more satisfied with the new joint due to its agility, lower energy consumption, and better support of the residual limb. “after walking on the microprocessor knee for two weeks it was difficult to go back to the hydraulic knee. i will not call it a shock, but i quickly realized how much i used the functions of the microprocessor knee. my brain adapted quickly to figure 3: comparison of individual functional scores. activities with no applicable scores included run (1), hobbies (1), walk in bad weather (2), sport (2), work (2), and walk in mud/sand (3). numbers in parentheses indicate the number of participants who marked the activity as “not applicable.” 0 10 20 30 40 50 60 70 80 pre test post test table 3: demographic and prosthetic characteristics of participants in the qualitative phase. subject gender cause of amputation age k level amputation level foot (pretest & posttest) pre-test knee l-test speed difference (m/s) function difference p1 male trauma 35 k3 kd triton & proflex lp 3r31 (otto bock) 6.4 7 p2 male congenital 31 k3 kd triton sideflex 3r80 (otto bock) 0.2 2 p3 male trauma 26 k4 bilateral vari-flex paso knee (ossur) 10.5 10 p4 male trauma 65 k4 kd trias & proflex lp 3r80 (otto bock) 3.4 16 p5 female trauma 74 k4 kd balance j & breeze) 3r106 (otto bock) 15.7 11 p6 male vascular 68 k2 tf pro-flex st aspire h1 (ossur) 19.3 6 s c o re s https://doi.org/10.33137/cpoj.v8i1.45286 6 visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/cpoj.v8i1.45286 canadian prosthetics & orthotics journal issn: 2561-987x magnetorheological knee use in south africa: function and experience visagie s and theron b, 2025 everything the microprocessor offered me in comparison with my other knee…the swing through of the knee was just easier. overall, i required less energy to walk with the knee. the knee helped a lot to decrease the effect and strain on my stump. i felt less tired at the end of the day.” p2 participants extolled how safe they felt using the rheo xc joint. “it is very safe. you feel safe on it. it will not give way under you. you have confidence. you do not have to be careful to prevent a fall. that [the guardedness against falling] is gone. it gives you confidence to walk and you can walk faster. it is the best leg i ever had… you have more control, balance and confidence. for sure. when you stand you stand solidly.” p4 these advantages translated into improved functionality. “i like fishing, i am next to the water, big clumps of grass, uneven ground. i do not want to place the other knees in a bad light, but if you put your weight wrongly on the foot it gives in. not this one. if there is weight on it, it is solid. that is a huge benefit.” p4 participant 6 felt a waterproof knee will enhance his functionally further. “i would have liked it to be waterproof. and that i can walk in the sand, in the swimming pool. in the sea… with my grandchildren in the shallow water.” p6 theme 2: real-world limitations of the mpk the weight of the rheo xc in relation to user strength must be considered during prescription. “the weight, it was extremely heavy. after the first 2 days i thought my left hip was dislocated.” p5 “obviously, the weight of the knee one can feel it immediately. even though there is less strain on your [remaining] knee you can tell you are walking with a prosthesis or a knee that is much heavier.” p2 the size of the rheo xc adds to the overall length of the prosthesis, which can be problematic for shorter people or those with long residual limbs. “i am short, so the knee with its fixed length and the foot that was at its lowest was still longer than my real right leg.” p5 participants felt the battery life was short. “i walked through the shops through the day then it starts peeping at me. i cannot understand why it is peeping. then i see the battery is going flat.” p4 another challenge that was raised was that the knee can hamper driving a vehicle as it might interfere with the pedals. “you struggle in a car because it just wants to go forward. then it is in the way of the pedal, the accelerator…you just lift your foot slightly and ‘zoep’ [local slang for something happening without warning] it wants to straighten.” p4 thus, for a successful prescription, knee characteristics must match user abilities. to ensure challenges are identified and the mpk is prescribed appropriately, a trial period is recommended. “the fact that there is a trial period is very good. walk with the knee. see what it does for you. is it sufficient for your needs? and if you feel it works for you, you have compared it with other knees and feel it ticks more boxes for you in your daily activities i will recommend it rather than a hydraulic or polycentric knee.” p2 discussion this mixed methods study explored and described south african users’ function and experience with the rheo xc knee. both user function and l-test scores showed improvement from pre-test to post-test. the positive impact of the knee joint was further supported by qualitative data. l-test scores exceeded both the normative values and the minimum detectable change (mdc95), which is the smallest improvement needed to be 95% confident that the change is clinically meaningful. the l-test norm is 41.7 s ± 16.8.33 the pre-test score was 6.3 s below this norm and the posttest score was 13.8 s below the norm. this might be due to the normative data being from 2005. the advancement of prosthetic components over the last 20 years should impact walking speed positively. the l-test mdc95 for persons with transfemoral amputations are 2.9 s.36 current data showed that 11 (68.75%) participants’ scores decreased with more than 2.9 s, with an average decrease of 7.51s across the group. from this it can be concluded that the change in scores is clinically meaningful and infers a change in ability rather than measurement error.37 the reduction in l-test time in the current study was similar to what was documented in previous similar studies. daviesmith and carse (2021)38 found that l-test scores decreased on average with 5.15 s after 6 months. participants in the study by davie-smith and carse (38) used a variety of mpks, with the most common being the kenevo and various versions of the c-leg. howard et al (2018)29 found a mean decrease of 7.4 s among three participants after switching from a nmpk to the rheo knee 3. they indicated that the l-test score for the other four participants was inconclusive without providing a mean for l-test score change across the group. functional level scores also improved significantly. previous research on the ottobock c-leg® and the 3e80, which features a microprocessor-controlled stance-swing phase switch, has similarly shown improvements in functional performance39 and walking speeds.40 the clinical value of the magnetorheological mpk was further supported by qualitative data, with participants reporting a positive experience using the device. in their opinion decreased energy use, a more fluid walking pattern, https://doi.org/10.33137/cpoj.v8i1.45286 7 visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/cpoj.v8i1.45286 canadian prosthetics & orthotics journal issn: 2561-987x magnetorheological knee use in south africa: function and experience visagie s and theron b, 2025 as well as improved agility, and safety translated to higher walking speeds. decreased energy consumption,5 increased agility5 and safety3,4,41 has been identified as advantages of mpks in previous research. for some participants, the rheo xc came close to replicating the function of their natural knee—an outcome that previous studies have shown users desire from their prostheses.1,2 the results showed that participants experienced important clinical benefits compared to their non-mpk knee. higher-level functions such as working, walking 100 meters, carrying shopping, and walking on uneven surfaces and hills showed the greatest improvement. this might be due to the safety features of the rheo xc, which allows movement, weight shift, turning, and change of direction without fear of falling as described by participants during the interview and shown in previous studies.4,7 at the same time activities requiring speed and high levels of agility such as running and participating in sport remained a challenge for many. although concerns have been raised that african conditions might be too harsh for an mpk, the current short-term findings did not support this. however, longer-term studies are needed to confirm its durability and performance. most participants indicated the ability to function on uneven surfaces and in mud and dust. qualitative findings provide examples of walking effectively in pastoral areas and pursuing outdoor activities. all participants had access to electricity to charge the battery. although a longer battery life would be beneficial. with these functional gains and previous research showing the long-term economic benefits of mpks,6,7 it is important that the south african government and other funders of prosthetic components in south africa consider mpks alongside other prosthetic knees. the initial monetary outlay might be compensated for by savings in the long run and better user function. savings occur because mpks have a longer life cycle than mechanical knees as reported by kuhlman et al,7 come with a warrantee (two years in the case of the rheo xc knee), of which the cost is included in the initial price of the mpk,7 that guarantee free of charge maintenance, and reduces falls and thus costs incurred because on injury.6,7 the economic benefits of better function and a wider range employment options have not been researched. while quantitative findings indicate that rheo xc knee joint improved function for all the participants, qualitative data showed that it was not the most optimal solution for all. the size of the joint makes it unsuitable for a shorter person with a through knee amputation or with a long transfemoral residuum. the weight was also concerning to some as also shown previously.38 lighter mpks or nmpks might be more suitable for frail users or users with weak residual leg muscles. these findings support the notion that prosthetic knee prescription should be based on user characteristics and functional needs. ideally users should be offered trial periods with different components before a knee is prescribed. the study results must be interpreted against the limitations discussed in the methods section and summarized here. the pre-test, post-test design suffers from a lack of a control group. the reasons for choosing this design, along with potential challenges, are outlined in the methods section.28,29 these challenges were further mitigated by triangulating the preand post-test results with qualitative findings.25 the small number of participants, lack of information on users whose trial requests were rejected, and the need to change the foot in some instances to a low profile foot reduce the generalizability and internal validity of the results. the combined data collection tools were not tested for reliability and validity. additionally, interrater bias may have occurred during the l-test, as different prosthetists timed different users. while the second author verified the codes and themes, independent coding and consensus-building were not conducted during the qualitative data analysis. conclusion this study provides context specific evidence that may support funding of the magnetorheological mpk in south africa. however, it is not suitable for everyone, and a trial period to assess appropriateness is advised before prescription. this evidence may benefit south african users, providers, and funders by assisting in the selection and prescription of appropriate knee components. research is recommended to determine whether the improved functioning supported by mpks translates into enhanced employment opportunities and income generation. acknowledgements thank you to the participating prosthetists and users without whom this study would not have been possible. declaration of conflicting interests the study was funded by the ossur company. the primary author is not employed by the company, but she was re-imbursed for her work on this study. the second author is employed by the company. this conflict of interest might have an influence on the interpretation of findings. the data are available upon request for independent analysis. authors contribution • surona visagie: assisted with study conceptualization and qualitative data collection, analyzed both qualitative and quantitative data, and drafted and finalized the article. • benje theron: assisted with study conceptualization, managed quantitative data collection, contributed to qualitative https://doi.org/10.33137/cpoj.v8i1.45286 8 visagie s, theron b. south african users’ function and experience with a magnetorheological microprocessor knee: a mixed methods study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 5. https://doi.org/10.33137/cpoj.v8i1.45286 canadian prosthetics & orthotics journal issn: 2561-987x magnetorheological knee use in south africa: function and experience visagie s and theron b, 2025 data collection, verified themes, and provided input on the article. sources of support the study was funded by the ossur company. references 1.murray cd, forshaw mj. the experience of amputation and prosthesis use for adults: a metasynthesis. disabil rehabil. 2013;35(14):1133-1142, doi: 10.3109/09638288.2012.723790 2.jefferies p, gallagher p, philbin m. being “just normal”: a grounded theory of prosthesis use. disabil rehabil. 2018;40(15):1754-1763. doi: 10.1080/09638288.2017.1312564 3.berry d, olson m, larntz k. 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locomotor capabilities index in adults with lower-limb amputation undergoing prosthetic training. arch phys med rehabil. 2004;85(5):743-8. doi: 10.1016/j.apmr.2003.06.010 32.hafner bj, gaunaurd ia, morgan sj, amtmann d, salem r, gailey rs. construct validity of the prosthetic limb users survey of mobility (plus-m) in adults with lower limb amputation. arch phys med rehabil. 2017;98(2):277-285. doi: 10.1016/j.apmr.2016.07.026 33.deathe ab, miller wc. the l test of functional mobility: measurement properties of a modified version of the timed “up & go” test designed for people with lower limb amputations. phys ther. 2005;85(7):626-635. doi: 10.1093/ptj/85.7.626 34.etikan i, musa sa, alkassim rs. comparison of convenience sampling and purposive sampling. american journal of theoretical and applied statistics. 2016;5(1):1-4. doi: 10.11648/j.ajtas.20160501.11 35.braun v, clarke v. reflecting on reflexive thematic analysis, qualitative research in sport. exercise and health. 2019;11(4):589-597. doi: 10.1080/2159676x.2019.1628806 36.hunter sw, frengopoulos c, holmes j, viana r, payne mw. determining reliability of a dual-task functional mobility protocol for individuals with lower extremity amputation. arch phys med rehabil. 2018;99(4):707-12. doi: 10.1016/j.apmr.2017.12.008 37.seamon ba, kautz sa, bowden mg, velozo ca. revisiting the concept of minimal detectable change for patient-reported outcome measures. phys ther. 2022;102(8):pzac068. doi: 10.1093/ptj/ pzac068 38.davie-smith f, carse b, 2021. comparison of patient-reported and functional outcomes following transition from mechanical to microprocessor knee in the low-activity user with a unilateral transfemoral amputation. prosthet orthot int. 2021; 45(3),198-204. doi: 10.1097/pxr.0000000000000017 39.theeven p, hemmen b, rings f, meys g, brink p, smeets r, et al. functional added value of microprocessor-controlled knee joints in daily life performance of medicare functional classification level-2 amputees. j rehabil med. 2011;43(10):906-15. doi: 10.2340/16501977-0861 40.fuenzalida squella sa, kannenberg a, brandão benetti â. enhancement of a prosthetic knee with a microprocessor-controlled gait phase switch reduces falls and improves balance confidence and gait speed in community ambulators with unilateral transfemoral amputation. prosthet orthot int. 2018;42(2):228-35. doi: 10.1177/0309364617716207 41.wong ck, rheinstein j, stern ma. benefits for adults with transfemoral amputations and peripheral artery disease using microprocessor compared with non-microprocessor prosthetic knees. am j phys med rehabil 2015;94:804y810. doi: 10.1097/phm.0000000000000265 https://doi.org/10.33137/cpoj.v8i1.45286 volume 6, issue 2 2023 articles in this special issue has been invited and reviewed by dr. silvia ursula raschke and dr. hossein gholizadeh. d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e v o l u t i o n i n p r o s t h e t i c s & o r t h o t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x https://jps.library.utoronto.ca/index.php/cpoj/editorinchief 1 dechev n, knights k, arklie k, martindale m, peirone m. accessible prosthetic arms: victoria hand project and the impact of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.9. https://doi.org/10.33137/cpoj.v6i2.42142 stakeholder perspectives accessible prosthetic arms: victoria hand project and the impact of 3d printing dechev n1,2,3*, knights k2,3, arklie k3, martindale m3, peirone m2,3 1 biomedical designs and systems laboratory, university of victoria, victoria, v8p 5c2, canada. 2 department of mechanical engineering, university of victoria, victoria, v8p 5c2, canada. 3 victoria hand project, 3060 westridge place, victoria, bc, v9e 1c8, canada. introduction the field of prosthetics and orthotics has witnessed transformative changes in recent years, driven by advances in rapid prototyping technologies (i.e., 3d printing, 3d scanning, and 3d computer aided design (cad)). this article describes the experience of victoria hand project (vhp) using these technologies to implement low-cost prosthetic applications, including the benefits and challenges encountered. vhp's journey has leveraged this new technology, in conjunction with tried-and-true traditional manufacturing methods, to provide prostheses to people with upper limb amputations, who face with limited access to prosthetic care. victoria hand project: a brief overview vhp is a registered canadian charity with a mission to help people in-need receive prosthetic arms. incorporated in 2015, vhp partners with prosthetic care professionals worldwide. partners are provided with equipment, training, and on-going support to enable them to create and provide prosthetic arms in their own clinics, for people in their own community. this model lays the groundwork for local, sustainable, and on-going care for people with upper limb amputations who may not be able to receive a prosthetic device otherwise. receiving a victoria hand is transformative: functional prosthetic arms are a vital tool to help people regain independence, hope, and opportunities to live more fulfilling and happier lives. the impact goes far beyond the recipient, with positive effects for their families, caretakers, and for increased clinic capacity. the vhp 3d printed prosthetic system has evolved over the years, with many thousands of hours devoted to engineering design and testing. there has been on-going close consultation with canadian, us, and international prosthetists, as well as feedback from hand recipients, which has informed the design direction. vhp has developed a range of prosthetic arm systems, and continually worked to improve the fit, cosmetic appearance, and function of these. each prosthetic system is customized by selecting from dozens of possible components such as various: terminal devices, wrists, custom limb sockets, and harness components. these are selected, combined, and further customized to suit the unique needs of each person. terminal devices options include: a voluntary close hand, a voluntary open hand, a cosmetic-passive hand, and a voluntary close pediatric hand. recipients are encouraged open access abstract victoria hand project (vhp) is a canadian charity with a mission to provide 3d printed prosthetic arms to people in-need across the world, by partnering with prosthetic care providers. this article explores the journey of vhp, sharing insights, lessons learned, ongoing directions, and the impact of 3d printing on prosthetic care for people with upper-limb amputation. benefits such as affordability and customization are explored, as well as the challenges encountered, including quality control and the steep learning curve associated with working in the digital 3d space. through this article, the potential of 3d printing to continue to transform the field of assistive technology and prosthetic and orthotic applications is underscored, especially when used for collaborative, humanitarian initiatives. citation dechev n, knights k, arklie k, martindale m, peirone m. accessible prosthetic arms: victoria hand project and the impact of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.9. https://doi.org/10.33137/cpoj.v6i2.42142 keywords 3d printing, 3d printed prosthetic arm, 3d printed hand, additive manufacturing, charity, humanitarian * corresponding author: nick dechev, phd biomedical designs and systems laboratory, university of victoria, victoria, v8p 5c2 canada. e-mail: dechev@uvic.ca orcid id: https://orcid.org/0000-0002-7731-0280 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.9. 2023 special issue https://doi.org/10.33137/cpoj.v6i2.42142 https://www.victoriahandproject.com/ https://www.victoriahandproject.com/ https://doi.org/10.33137/cpoj.v6i2.42142 https://orcid.org/0000-0002-7731-0280 https://jps.library.utoronto.ca/index.php/cpoj/index 2 dechev n, knights k, arklie k, martindale m, peirone m. accessible prosthetic arms: victoria hand project and the impact of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.9. https://doi.org/10.33137/cpoj.v6i2.42142 canadian prosthetics & orthotics journal issn: 2561-987x victoria hand project and the impact of 3d printing dechev et al., 2023 (special issue) to pick and choose between features that work best for them and their lifestyle. vhp offers 3d printed limb sockets for various amputation levels, including trans-radial options for below-elbow amputations, using a pla (polylactic acid) socket for longer residual limbs, and a flexible polypropylene inner socket with a rigid pla outer socket for shorter residual limbs. additionally, a trans-humeral system is available for people with above-elbow amputations, comprising a pla upper limb socket, stainless steel elbow mechanism, and pla forearm. given all these possible options and combinations, vhp has recently developed software to aid prosthetists in the workflow, and also integrated 3d cad to facilitate socket creation. in this way, by partnering with local clinics, and training them in this production system, vhp’s approach allows for high-quality care and builds in-country institutional capacity. to date, vhp has provided over 300 victoria hand prosthetic arms worldwide, trained over 50 clinicians in rapid prototyping technology, and established 11 on-going partnerships in: cambodia, canada, egypt, guatemala, haiti, kenya, nepal, pakistan, uganda, ukraine, and the united states. personal anecdotes from recipients demonstrate the benefits from increased function, increased self-esteem in public, to becoming more independent at home and work. it is important to explain that vhp systems were specifically designed to minimize cost and thereby maximize accessibility worldwide, where they are approximately $100-150 usd in materials depending on the system. designing prosthetic devices to meet such a low cost has major implications and has driven the nature of the tools and methods used, as explained in this paper. design philosophy & benefits of 3d printing customizable socket creation: the workflow of creating a 3d printed socket begins with the prosthetist taking anatomical measurements of both upperlimbs, making a traditional plaster limb impression of the residual limb, creating a positive cast, rectifying it, and then 3d scanning the positive impression. this retains the clinicians’ sense of tactile feedback, for them to incorporate space or padding in the socket (via positive impression) as needed for each patient. after scanning, the 3d scan is then imported into vhp’s software, which guides the clinician through the process of turning the impression into a 3d printable limb socket. employing 3d printing introduces benefits: this frees prosthetist and technician time, to concentrate their expertise on patient care. the 3d printers can fabricate parts without clinician intervention, where a large limb socket may print in 8-10 hours overnight without any interaction needed. if terminal devices are printed and assembled ahead of time and kept “in stock”, a patient could visit a clinic, be measured and cast, and receive a custom prosthetic system the next day. this process reduces equipment needs, since there is no longer a need for oven heaters, draping hot plastic sheets, vacuum systems, trimming and grinding equipment, or other infrastructure for making traditional sockets. it allows for complex shapes to be manufactured directly into sockets (connection points, cable guides, wrist connectors) thereby digitally integrating several traditional components/features into a single socket. this reduces traditional inventory since components/ features can be printed on-demand. the socket interior shape is replica of the impression, whereas the exterior body is a parametric shape by using patient measurements, where the average thickness is 8mm. rapid prototyping for quick production: vhp’s prosthetic devices are made by using a variety of different rapid prototyping technologies and widely available parts. the primary design goal is low-cost, highly functional, durable prosthetic arm systems that can be built on-site in various countries worldwide. this is achieved by using 3d printing, 3d scanning, 3d cad, and also 2d laser-cutting (a more recent rapid prototyping technology). several lasercut stainless-steel components (cut from 1.9 mm stainless steel sheet) are used in the terminal devices (hands), elbow, back-lock, and for small, high-stress parts within the prosthesis, to ensure durability and long life. 3d printing allows for manufacturing of parts in small batches, without the need to inventory hundreds of different parts (as is traditionally done). printing on-demand parts mean less supply-chain disruption, fewer shipping and import fees, fewer delays, and enables on-site service/repair in hard-toreach places in the world. cost effective design: rapid prototyping allows for low-cost production of prosthetic devices. materials for a complete vhp prosthetic system, cost approximately $100 to $150 usd, compared to conventional devices that cost several thousands.1,2 vhp provides stipends (per fitting) to the international partner clinicians and technicians, who are each paid $100 to $150 usd to support their business and livelihood, bringing the total cost for provision of a vhp system to between $300$450 usd depending on the location and configuration. this is approximately 10% of the estimated cost to receive a body-powered hook.2 vhp’s partnership agreement offers the devices to prospective amputees on a pay-what-youcan model, and often free to those most in need. since vhp is a charity, development costs do not need to be recovered, further keeping device costs low. rapid global design updates: with rapid prototyping, design improvements and feature updates to prosthetic devices can be transmitted digitally and instantly. since parts are 3d printed on-demand, design https://doi.org/10.33137/cpoj.v6i2.42142 3 dechev n, knights k, arklie k, martindale m, peirone m. accessible prosthetic arms: victoria hand project and the impact of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.9. https://doi.org/10.33137/cpoj.v6i2.42142 canadian prosthetics & orthotics journal issn: 2561-987x victoria hand project and the impact of 3d printing dechev et al., 2023 (special issue) improvements can be implemented rapidly. when international clinical partners share patient feedback that warrants a design change, vhp engineers can make the change in canada, build it, test it and then push the new designs (as digital files) via the software to partners. version control is an important aspect for vhp, where each 3d printed part has a date-based model number inscribed. in-country production: on-site, on-demand 3d printing also enables the rapid replacement of worn/broken parts, reducing downtime for individuals and clinics. the aforenoted version control also preserves ability to re-print legacy (older) 3d parts for repair of older systems. technicians and clinicians can quickly make adjustments and repairs. this ensures that people travelling to the clinic can receive care and maintenance promptly, minimizing the challenges of travel and long wait times without their device. details and challenges of 3d printing vhp collaborates with the university of victoria’s engineering faculty (biomedical design and systems laboratory) to perform extensive mechanical and other testing on 3d printed parts before deployment. through this process a wealth of information has been learned over the past decade, where some recommendations are summarized here: design for 3d printing: the most significant challenge in 3d printing for prosthetics or orthotics applications is ensuring the strength and durability of the devices compared to traditionally manufactured ones. vhp prosthetics are made using the fdm (fused deposition modelling) 3d printing method, which is the successive addition of thin layers (0.4 mm to 0.6 mm) of molten plastic material, to build up a desired part layer-by-layer. as such, the tensile strength of 3d printed parts is different along different directions (non-isotropic), where there is relatively high-strength in-plane of the layer, and relatively low-strength between the layer planes. this is referred to as inter-layer adhesion. different materials, and variability in print settings (layer height, nozzle diameter and temp, infill density, part-orientation, and print speed) will also impact the final part’s strength. given the limitation of inter-layer adhesion, vhp makes extensive use of small threaded bolts and nuts, within various prosthetic parts. this serves to maintain compression between layers, to maximise tensile and bending strength. this is used within the various terminal devices, the wrists, and the elbow. vhp also makes extensive use of metal components for very small, high-stress parts. for example, 2 mm diameter pins of various lengths for rotational elements in the fingers, within the palm, the wrist, the force doubler and other components. recently, the incorporation of laser-cut stainless-steel components has been introduced to function as internal structural elements, akin to the bones (phalanges) within the fingers, as well as structural elements within the hands, the elbow and the force doubler. this combination of 3d printed pla and metal parts, provides the distinct advantages of each approach, resulting in devices that exhibit optimal functionality, aesthetics, cost-efficiency, and durability. materials: pla (polylactic acid) material is used for rigid/hard components of the prosthesis, including sockets. although many dozens of materials have been extensively tested, it was found that pla is by far the best material for various factors: biocompatible (body contact wearable safe) for some brands,3 most reliable material (least 3d print failures, least jammed nozzles, etc), most durable material (3-5+ years of service life), lowest cost and most widely available, great strength (almost as strong as abs) vs cost, best 3d printed results over a range of print settings. vhp has great success with two different pla materials: basf forward am pla material which is certified body-safe,3 and formfutura easyfil pla, where the black color material has the highest strength (rigorously tested by vhp). testing: rigorous benchtop testing of the various devices has been done, using several or more replicate tests. some examples include: finger testing, where a finger (within the prosthesis) is loaded at the tip in extension, where on average a single finger can hold 80 lbs (356 n) of weight without failure. wrist testing, where the ball and socket wrist is loaded such that the prosthesis can hold 43 lbs (190 n) at a distance of 7.5 cm from wrist (torque of 14 n-m), before failure. note wrist slip rotation will occur at 11 lbs (47 n, torque of 4.9 n-m). elbow joint testing, where the prosthesis is loaded at the distal end of the forearm (19 cm from elbow), with an average weight of 18 lbs (80 n) before slip rotation (torque of 15.2 n-m). the voluntary close hand (vc300) weighs 1.5 lbs (0.68 kg), with the total transradial prosthetic system, including the hand, wrist, transradial socket, cabling and harness, weighing approximately 3 lbs (1.4 kg). similarly, the transhumeral system consisting of a vc300, the wrist, a forearm, elbow mechanism, upper transhumeral socket, cabling and harness is a total of approximately 5 lbs (2.3 kg). 3d printers: there is a large variability amongst 3d printers, with hundreds of different models available. vhp has found the best value in terms of performance-to-cost with the ultimaker brand of 3d printers, in particular the ultimaker https://doi.org/10.33137/cpoj.v6i2.42142 4 dechev n, knights k, arklie k, martindale m, peirone m. accessible prosthetic arms: victoria hand project and the impact of 3d printing. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.9. https://doi.org/10.33137/cpoj.v6i2.42142 canadian prosthetics & orthotics journal issn: 2561-987x victoria hand project and the impact of 3d printing dechev et al., 2023 (special issue) 2+ extended and the ultimaker connect, as well as the prusa xl 3d printers. these machines exhibit great reliability in various environments (dust, temperature, humidty), handle thousands of print hours, are easy serviceability with low cost, and have good build-volume and build height (fundamentally important for creating large/long sockets). by exclusively utilizing these 3d printers, predetermined print settings, and the aforementioned pla material, vhp ensures consistent and well-controlled 3d printed parts. this meticulous standardization not only enhances production efficiency but also guarantees the reliability and quality of each prosthetic arm, as mandated by partnership agreements with international partners. challenges: a major challenge faced by vhp was training partner clinicians in 3d digital technology (printing, scanning, cad), and integrating that with conventional prosthetic fabrication methods. there is a steep learning curve associated with computer aided design (cad), working with and visualizing 3d meshes on-screen, and 3d scanning. many clinicians are already busy with their day-to-day work and may not have the time available to learn these new skills in-depth. vhp recognises the importance of making this technology accessible and easy-to-understand for clinicians and has created comprehensive training procedures and as well as in-house software programs dedicated to making the learning process easier and more intuitive. by providing clinicians with the necessary skills and knowledge to work with 3d-printing technology, vhp provides them with new tools to use in conjunction with traditional methods. call to action readers (prosthetists, technicians, and clinicians) are encouraged to consider the techniques and methods introduced in this paper. rapid prototyping can contribute in significant or subtle ways to the construction of prostheses, and various possible approaches exist. consequently it can enhance lives and contribute to the advancement of prosthetic technology. the authors can share more specific details with interested parties upon request. acknowledgements vhp would like to recognize and extend gratitude to all prosthetist partners who generously volunteer their time, expertise, and efforts to provide 3d printed victoria hands via their clinics. appreciation is also extended to the generous philanthropists, corporations, and passionate individuals who have made the vhp services possible. declaration of conflicting interests dr. nick dechev is the founder of victoria hand project, a charitable organization dedicated to providing affordable prosthetic care to underserved populations. kelly knights is the chief operating officer, kim arklie is mechanical engineer, michelle martindale is biomedical systems designer, and michael peirone is chief executive officer at the victoria hand project. authors contribution nick dechev emphasizing design philosophy and the benefits of 3d printing, kelly knights, and kim arklie focusing on technical aspects, michelle martindale, focusing on rapid global design updates, and michael peirone focusing on details and challenges of 3d printing. all authors provided final approval for the version to be published and agreed to be accountable for all aspects of the work. the experiments were planned and carried out collaboratively by n.d., k.k., k.a., m.m., and m.p. including data acquisition, analysis, and interpretation. all authors, including n.d., k.k., k.a., m.m., and m.p., actively contributed to the interpretation of results, sample preparation, and critical feedback, helping shape the research, analysis, and manuscript. sources of support this project has received support from choose love (2023), fauji foundation (2023), td bank (2019), google.org (2017), grand challenges canada (2014, 2016), and nserc (2014). references 1.zuo kj, olson jl. the evolution of functional hand replacement: from iron prostheses to hand transplantation. plast surg (oakv). 2014 spring;22(1):44-51. pmid: 25152647; pmcid: pmc4128433. 2.solomonov d. prosthetic arm costs and financing: a comprehensive guide [internet]. groupenroll.ca. [cited 2023 sep. 23]. available from: https://groupenroll.ca/prosthetic-arm-costsguide 3.biocompatibility product information, product: ultrafuse® pla pro1 [internet]. basf 3d printing solutions. [cited 2023 sep. 23]. available from: https://move.forwardam.com/hubfs/aes%20documentation/engineering%20filaments /pla%20pro1/biocompatibility%20statement_ultrafuse%c2%a e%20pla%20pro1_en.pdf corresponding author scientific biography nick dechev is an associate professor in the department of mechanical engineering at the university of victoria, and former program director for biomedical engineering. he has a strong background in biomedical systems design, mechatronics, robotics and automation, assistive technology, and 3d printing. nick’s research focuses on developing innovative solutions to enhance the lives of individuals with disabilities, particularly in the field of prosthetic and orthotic devices. he is the founder of victoria hand project, a charitable organization dedicated to providing affordable prosthetic care to underserved populations. https://doi.org/10.33137/cpoj.v6i2.42142 https://groupenroll.ca/prosthetic-arm-costs-guide https://groupenroll.ca/prosthetic-arm-costs-guide https://move.forward-am.com/hubfs/aes%20documentation/engineering%20filaments/pla%20pro1/biocompatibility%20statement_ultrafuse%c2%ae%20pla%20pro1_en.pdf https://move.forward-am.com/hubfs/aes%20documentation/engineering%20filaments/pla%20pro1/biocompatibility%20statement_ultrafuse%c2%ae%20pla%20pro1_en.pdf https://move.forward-am.com/hubfs/aes%20documentation/engineering%20filaments/pla%20pro1/biocompatibility%20statement_ultrafuse%c2%ae%20pla%20pro1_en.pdf https://move.forward-am.com/hubfs/aes%20documentation/engineering%20filaments/pla%20pro1/biocompatibility%20statement_ultrafuse%c2%ae%20pla%20pro1_en.pdf all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 1 2024 review article galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i1.43827 1 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 review article active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists galbert a, buis a* department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. introduction upper limb impairment, resulting from a range of factors such as injury, neurological disorders, diseases, conditions, and general comorbidities, can have a profound and detrimental impact on an individual's overall quality of life.1 this impairment often leads to significant limitations in physical activity2,3 and can contribute to mental health challenges, due to the loss of independence and functionality.4 symptoms such as muscle weakness, reduced muscle control, neurological issues, and prehension difficulties vary in severity and permanence. due to this variability, a one-size-fits-all approach is inadequate. tailored rehabilitation programs and assistive interventions must be designed to accommodate the specific requirements of individuals, enabling them to perform activities of daily living (adls) more effectively and improving their overall well-being. spasticity, muscle weakness and prehension difficulties affect the upper limb differently. spasticity is defined as velocity-dependent resistance,5 due to this muscle contracture, impaired control of voluntary hand-opening tasks and activities is seen.4 in contrast, muscle weakness affects hand-closing tasks such as grasping utensils and opening doors. the hands are the only prehensile organ in the human body.6 prehension is required for feedback during tasks and coordination, therefore reduced prehension disrupts the balance between power and precision requirements of dexterous tasks.7 when a person receives no feedback during functional tasks, they may be open access abstract background: assistive technology is often incorporated into rehabilitation and support for those impacted by upper limb impairments. when powered, these devices provide additional force to the joints of users with muscle weakness. actuated devices allow dynamic movement compared to splints, therefore improving the ability to complete activities of daily living. however, these devices are not often prescribed and are underrepresented in research and clinical settings. objective: this review examined the existing literature on devices developed to support hand and wrist functionality in daily activities. focusing on active, powered, and actuated devices, to gain a clearer understanding of the current limitations in their design and prescription. methodology: the scoping review was conducted using the prisma-scr guidelines. a systematic search was done on medline, embase, scopus, web of science, and nhs the knowledge network from inception to may 2023. articles were included if the device was portable; supported the hands and wrist actively using an actuator; and could be used for assistive living during or post-rehabilitation period. findings: a total of 135 studies were included in the analysis of which 34 were clinical trials. the design and control methods of 121 devices were analyzed. electrical stimulation and direct mechanical transmission were popular actuation methods. electromyography (emg) and joint movement detection were highly used control methods to translate user intentions to device actuation. a total of 226 validation methods were reported, of which 44% were clinically validated. studies were often not conducted in operational environments with 69% at technology readiness levels ≤ 6, indicating that further development and testing is required. conclusion: the existing literature on hand and wrist exoskeletons presents large variations in validation methods and technical requirements for user-specific characteristics. this suggests a need for well-defined testing protocols and refined reporting of device designs. this would improve the significance of clinical outcomes and new assistive technology. article info received: august 12, 2024 accepted: october 31, 2024 published: november 8, 2024 citation galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1 .43827 keywords upper limbs, exoskeletons, assistive devices, wearable devices, design, actuators, outcome measures, systematic review, daily activities, wrist, electromyography, hand. please refer to the end of the article for a list of abbreviations. * corresponding author: professor arjan buis, phd department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. e-mail: arjan.buis@strath.ac.uk orcid id: https://orcid.org/0000-0003-3947-293x journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 1, article no.9. 2024 https://doi.org/10.33137/cpoj.v7i1.43827 https://doi.org/10.33137/cpoj.v7i1.43827 https://doi.org/10.33137/cpoj.v7i1.43827 mailto:arjan.buis@strath.ac.uk https://orcid.org/0000-0003-3947-293x https://jps.library.utoronto.ca/index.php/cpoj/index 2 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 unable to gauge if they have optimal hand orientation or enough strength to hold an item. hand and wrist impairments of all types target a person’s ability to perform adls. in addition to performing adls, biopsychosocial factors are also impacted by hand impairment.8 the biopsychosocial model is a concept which allows for the classification of factors which may contribute to any individual’s mental and physical health.9-11 the psychological impact of hand impairment can be presented as distress, depression, and low self-efficacy. persons with hand impairments have also shown a reduction of measures determining quality of life.2 sense of freedom, belonging and security are major social factors affected by having upper limb impairment.8 these people may also have reduced independence and may rely on family, caregivers, and allied health professionals for support. the biopsychosocial factors mentioned introduce a global burden on resources, cost, time and availability of support.12-14 fortunately, assistive technology may reduce that burden while also attaining sustainable development goals for the future ageing population affected by these impairments.15,16 to facilitate upper limb functional tasks, interventions such as rehabilitation and assistive technology may be provided. the objective of assistive technology is to ensure safety, and accessibility, promote independence and improve quality of life. to achieve these objectives, devices must be tailored to the user’s requirements. for users who require augmented strength and functionality to perform tasks, a powered and actuated device would be appropriate. examples of active devices include exoskeletons and exosuits.17 the introduction of actuators makes the device active, compared to passive devices that use elastics, levers and springs to support user motion such as dynamic orthosis. these devices function by applying force from an actuator on segments of the upper limb. actuators are devices which convert energy to motion; this energy may be electric such as dc motors. depending on the position and power of the force applied to the upper limb, the device can assist in various functional tasks. the evolution of upper limb assistive devices has had rapid advancements in technology. it has grown in popularity within the commercial sector as workplace health and safety systems, and as stationary end-effector devices within physical rehabilitation settings.18 despite the advantages of using these devices,16,19,20 the national service framework for long-term conditions and clinical commissioning groups (national to the united kingdom) have minimal to absent policies for using these motorized devices.21 the rationale behind this regulatory stance is uncertain. however, global reports on assistive technology have postulated several factors for the general lack of prescription of assistive devices including limited-service provision, inadequate products, market shortcomings, governance and funding constraints, as well as sociodemographic barriers.16 these factors may apply to actuated devices, but these reports16,21 do not focus on actuated devices. furthermore, literature reviewing the upper limb exoskeletons rarely discusses the hands and wrist segments,18 and of those which have, there is a lack of breadth on clinical utility and outcome measures.17, 20, 22, 23 based on the gaps in global reports and review literature, a study summarizing actuated devices would be appropriate. this scoping review aimed to explore the research question: what is known about active actuated and assistive devices for the hands and wrist? the secondary objectives include: 1) defining the intended populations of these devices, 2) abstracting an overview of the device design: including modes of actuation, user intention methods and force transmission methods, 3) summarize and categorize validation strategies used in the study of these devices. methodology a scoping review summarizing the breadth of existing literature concerning active, actuated (powered and motorized) and assistive (provides support during functional tasks) devices designed for the hands and wrists was conducted. the scoping review offers a methodological approach to survey the evidence, key concepts, and analyze knowledge gaps.24-27 this may illuminate potential rationales for the underrepresentation of hand and wrist assistive devices in literature. it may also ascertain if the barriers outlined in the global report on assistive technology16 apply to actuated devices. a scoping review was chosen as it maps out the extent of existing research on a broad topic. for this study, it is active assistive devices for hand and wrist actuation. scoping reviews have more inclusive eligibility criteria compared to systematic reviews. this encourages the use of larger sources of literature, more time-effective analysis, and provides evidence for future systematic reviews. this scoping review follows the preferred reporting items for systematic reviews and meta-analysis extension for scoping reviews (prisma-scr).28 this extension is an update from the prisma guidelines which is a validated systematic approach for evidence syntheses.24 the search criteria for the database were structured according to population, concept, context (pcc) framework.29 the population was defined as individuals experiencing hand and/or wrist impairment. the concepts focused on devices with active actuation and power. the context encompassed devices which assist adls during and post-rehabilitation. the definition of post-rehabilitation in this study refers to the phase of recovery and support that follows an initial rehabilitation program. https://doi.org/10.33137/cpoj.v7i1.43827 3 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 database search five databases were searched from inception to the date of search (may 25th, 2023). the databases selected were medline (ovid), embase (ovid), scopus, web of science, and nhs the knowledge network. no limitations or filters were applied to the results during the systematic database search. these databases were chosen based on their optimal combination, and collectively satisfy the minimum requirement of databases necessary to ensure adequate and efficient coverage of studies.30,31 search terms were combined with boolean logic ((hand or hands or extremity) and (wrist or wrists or carpus) and (device or devices or assistive devices or actuated devices or powered devices or exoskeleton or glove or dynamic) and (functional or function or assist or assistive or assistance or aid or aiding or support)). database search results were imported to endnote v20 in an ris file format. duplicates and retractions were removed using endnote v20 software. selection criteria two screening processes were used: the first examined titles and abstracts for all papers on microsoft excel 2018 version 2409. the inclusion criteria were “is this an active, actuated, and assistive device for the hands and wrist?”. papers were marked “include”, “exclude”, “duplicate” and “maybe”. the process of tagging studies was conducted by 2 reviewers with 86.9% agreement, and any disagreements were resolved with consensus. all studies tagged as duplicates were checked to ensure a version was kept within the dataset. the second screening process examined the full paper against the inclusion criteria shown in table 1. the studies were tagged with include or exclude using these criteria. data extraction a total of 24 data items were charted independently by researcher ag. the full list of data charting items collected, and their definitions can be found in table 2. records from the same research group were considered individually if the devices described were mechanically different from each other, whereas articles regarding different iterations of the same device were grouped with the latest prototype iteration considered. for records using the same device, the most representative across all papers was chosen. the data charting items provided a comprehensive summary of participants demographic features, interventions, validations, and technology readiness levels (trls) of the included studies. participants demographics include country, the sum of participants, gender, age, and patient conditions (if applicable). the intervention comprises device name, weight, degree of freedom (dof), mechanical transmission, user intent/detection methods, and limb segment the device supports. the synthesis of validation includes both clinical outcome measures and non-clinical. trls were also part of the data extraction and can be analyzed against all data items to investigate potential trends in technological advancements. results overview a total of 5,588 records were identified from the initial database search conducted in may 2023, of which 135 studies were included in the scoping review dataset.32 the selected studies were published between 1995 to 2023 (m = 2016, sd = 6.64), with 54% (73/135) studies published in the last 5 years. the selection process is provided in figure 1. two publications were identified and retracted using endnote software. the most popular methodology used an experimental design (25%, 34/135), followed by feasibility studies (21%, 28/135). clinical methodologies, such as rcts (randomized control trials, n = 12) and single group trials (n = 12), made up 34% (46/135) of the dataset. thirty-one countries contributed to the field of hand and wrist exoskeletons. of which, the usa (20%, 27/135), china (16%, 21/135), japan (12%, 16/135), italy (8%, 11/135) and south korea (6%, 8/135) produced the highest number of studies. table 1: exclusions criteria for second screening. decision tag exclusion criteria additional notes reason 1: is the device mobile? devices grounded to static tables are excluded, but devices mounted to wheelchairs are included as it is mobile. reason 2: does the device actively support hand and/or wrist movement? devices which immobilize joints are excluded. devices which support the wrist in a static position and do not support hand movement are also excluded. reason 3: is this a complete system? a complete system must include hardware and software. reason 4: does the device support adls? if the hand and wrist are put in a static position, it can be assumed adls are not being completed and therefore excluded. devices which train the hand/wrist for adls are included. reason 5: is the study primary research and not a review? excludes all reviews; examples include systematic, scoping, narrative, and state-of-the-art reviews. miscellaneous: access to full paper in english excludes research posters, published abstracts, and conference abstracts. excludes papers not provided with english translation. https://doi.org/10.33137/cpoj.v7i1.43827 4 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 table 2: list of all data items collected, and their definitions. data item definition title title of the article as found in the database. reference id reference number linked to list of all referenced in the dataset. author list of all authors. year the year the article was published. country of study the country of study is either given based on the institution or location of the clinic of the affiliated author. study type the study type was defined by the publisher. options cited include articles, research papers, case reports, letters, and pilot studies. method methodology of the study. sum of participants the sum of the participants in the study. male the sum of male participants (when provided). female the sum of female participants (when provided). age range based on the participants, the youngest to oldest participants make the age range. target population the intended population/user group for the device. grouped target population to reduce variations in a target population, the grouped target was separated into 22 subgroups with 13 unique groups that were often combined: • autoimmune disease • cardiovascular disease (cvd)/stroke • entrapment neuropathy • healthy • joint disorder • muscular dystrophy • musculoskeletal impairment • musculoskeletal injury • neurological disorder • sarcopenia • spinal cord injury (sci) • traumatic brain injury (tbi) • tremor study population the condition of the participants in the study. device name of the device if provided. weight of device (g) weight of the device on the upper limb unless specified otherwise. dof (degree of freedom) dof of the entire device refers to the number of independent ways the mechanical transmission can move joints in the hand/wrist. mechanical transmission method of applying active force from an actuator to the joint of the user. grouped mechanical transmission to reduce variations in mechanical transmissions, sub-classes were grouped into 6: • cable-conduit: these systems use cables or flexile wires inside a conduit. they transmit force in push or pull motions, like a brake cable on a bicycle. • direct: these systems transfer force directly to the joint segment, for instance, a linear actuator may push the wrist into flexion. • fluidic transmission: commonly hydraulic or pneumatic, these systems use pressurized fluids in a tube to control movement. • muscle contraction: to induce movement, electrical stimulation is used to contract (shorten) the muscle. the placement of electrical stimulation triggers various joint movements. • pulley: as a motor turns, the pulley system amplifies the force and moves the joint segment attached to the system. • supernumerary: these systems include extra robotic limbs such as fingers or hands. these devices aid in functional tasks by providing additional force. hand/wrist is the device aimed to support the hand, the wrist, or the hand and wrist together? user intent/detection methods the user intent/detection methods are how the device is controlled. the user will actively trigger the device, this can be by using a joystick, by contracting muscles, and many more. outcome measures all outcome measures and outcome measurement tools that were used in the study. technology readiness level (trl) the trl was assigned according to the trl definition provided by the horizon 2020 work program 2014-2015 defined in table 4. the trl is a scale used to measure how developed and ready a technology is for practical use. outcome measure field the outcome measures were separated into clinical, technical, or clinical and technical measures. clinical outcomes focus on the patient’s health and quality of life, technical outcomes focus on the functionality and performance of the device. classification of outcome measures was aided by the who icf model.11 https://doi.org/10.33137/cpoj.v7i1.43827 5 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 following the world development indicators for income classification,33 3 studies were completed in low-middle income economies,34-36 31 in upper-middle income and 101 in high income. the correlation (r) between the number of studies published per country and the sum of participants was foreseeably high (r=0.867). an outlier to this trend is one study from russia by abramovich et al,37 which included 96 participants. this was also the second largest sum of participants in one study, with the largest sum of participants in a study conducted by takebayashi et al with 115 participants.38 participants the sum of participants within the dataset totaled 1310. of the 1310 participants (female: male 39%:61%), 46% (597/1310) had upper limb impairment due to stroke, 28% (371/1310) have been affected by spinal cord injury (sci) in the form of tetraplegia, hemiparesis, or hemiplegia, and 11% (140/1310) were considered healthy. the least reported conditions for support included persons with cerebral palsy40 with 19 participants, upper limb tremors34,41 with 20 participants, parkinson's disease36 with 10 participants, and support post-burns42 with 20 participants. of the 39 studies which recruited healthy participants solely, two devices43,44 were intended for human augmentation in healthy user groups. age of participants ranged from 12-83 years old: two studies45,46 included a device for non-adults. intervention in all, 121 devices were presented within the studies. a summary of the devices is presented in table 3. devices were categorized by their weight (g), degree of freedom (dof), power transmission, mechanical transmission, segment of support (hand and or wrist) and user intent. of the target support joint, 37% (45/121) of devices supported hand actuation, 36% (44/121) supported both the hand and wrist and 26% (32/121) supported wrist actuation only. figure 1: prisma flowchart of database search, inspired by prisma2020.39 identification of studies via databases d a ta b a s e s s c re e n in g records identified: medline (n 1 1) embase (n 1 2 2) scopus (n 1 4) web of science (n 1 211) nhs (n 200) records removed before screening: duplicate records (n 1 1) records retracted (n 2) records excluded (n 201) records not retrieved (n 11 ) records screened (n 4 0 ) records sought for retrieval (n 4) records assessed for eligibility (n ) studies included in review (n 1 ) records e cluded: reason 1: not wearable and portable (n ) reason 2: not a hand and/or wrist device (n ) reason 3: not a complete system (n 1 ) reason 4: does not support adls (n 1 ) reason 5: review (n 2 ) in c lu d e d https://doi.org/10.33137/cpoj.v7i1.43827 6 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 table 3: summary of devices analyzed. device name reference weight of device on arm (g) dof power transmission mechanical transmission hand/ wrist user intent 2-channel portable battery47operated fes system 47 3 electrical stimulation muscle contraction hand and wrist emg signal 3-crp 48 2700 3 dc motors direct hand and wrist concurrent movement 4-dof wheelchair exoskeleton and carbon hand 49 4000 4 maxon dc motor cable and gear hand and wrist joint position and tactile a5 hand function training system 42 6 linear actuator bar linkage hand and wrist muscle torque anthropomimetic upper limb assistive device 35 12 dc motors pulley hand and wrist manual selection armeo power ii 50 205000* 7 motors gears wrist joint torque attention-controlled wrist rehabilitation method 51 415 2 linear actuator push-pull cable wrist eeg signal botas 52 6 electrical stimulation direct hand and wrist emg signal and eeg signal bridge empatia 53 5 stepper motor bar linkage wrist manual selection (joystick) diadens-pkm 54 350 electrical stimulation muscle contraction wrist emg signal distributed fes and assessment system 55 2 electrical stimulation muscle contraction hand and wrist concurrent emg signal and finger angle dtf splint 56 1 pneumatic actuator pneumatic hand manual selection dtsam orthosis 57 2 pneumatic actuator pneumatic wrist joint angle dulex-ii 58 504 3 pneumatic and linear actuator pneumatic hand and wrist concurrent emg electrical stimulation 59 electrical stimulation muscle contraction wrist manual selection electromechanical orthosis and myosystem bri system 60 2 dc motors pulley hand and wrist emg emg-driven exoneuromusculoskeleton 61 368 pneumatic actuator pneumatic hand muscle torque emg-driven nmes-robotic arm 62 dc servo motors direct wrist emg signal emg-driven nmes-robotic hand 63 4 linear actuator bar linkage hand emg emg-driven wh-enms 64 5 pneumatic actuator pneumatic hand and wrist emg emotiv epoc and rehastim 65 electrical stimulation muscle contraction hand and wrist eeg signal empi focus 66 electrical stimulation muscle contraction hand and wrist manual selection ems 400 and ultraflex 40 2 electrical stimulation muscle contraction wrist manual selection energy-efficient wrist exoskeleton 67 1 pneumatic actuator pneumatic wrist joint angle ets-marse 68 7072 7 brushless dc motors gears wrist muscle torque ewrist 69 556 1 brushless dc motors gears wrist joint angle and emg signal exofinger 70 2 dc servo motors bar linkage hand emg signal, finger temperature and joint angle exotic upper limb exoskeleton and itci and carbon hand 71 6000 4 maxon dc motor cable and gear hand and wrist manual tongue exo-wrist 72 1003 2 rotary encoder pulley wrist muscle torque extend exoskeleton 73 105 3 linear actuator bowden cable hand manual selection fesia grasp device 74 91 8 electrical stimulation muscle contraction hand and wrist emg signal fesmate ce1230 75 electrical stimulation muscle contraction hand and wrist emg https://doi.org/10.33137/cpoj.v7i1.43827 7 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 table 3 (continued): summary of devices analyzed. device name reference weight of device on arm (g) dof power transmission mechanical transmission hand/ wrist user intent fesmed 4050 device 76 200 electrical stimulation muscle contraction hand and wrist manual selection five-digit 3d printed battery-powered and force augmenting orthotic exoskeleton 77 linear actuator cable hand muscle torque five-fingered exoskeleton hand 78,79 2000 3 dc motors bar linkage hand and wrist emg and wrist joint angle flexohand 80 280 6 dc servo motors bowden cable hand manual selection foot-controlled hand/forearm exoskeleton 81 4 dc servo motors pulley hand and wrist manual foot selection gbbas 82 95 3 pneumatic actuator pneumatic hand joint angle and muscle torque gloreha lite glove 83 80 5 pneumatic actuator pneumatic hand manual selection glove-based assistive device 84 2 pneumatic actuator pneumatic wrist wrist movement graspyglove 85 340 4 maxon dc motor push-pull cable hand sensor proximity hand assistive device 86 1 linear actuator bowden cable hand muscle torque (index) hand exoskeleton 87 114 3 dc motors bowden cable hand joint angle and muscle torque hand exoskeleton system hes 88 350 2 dc servo motors bar linkage hand manual hand hand function rehabilitation robot 89 450 2 linear actuator bar linkage hand manual hand (touch screen) hand/wrist exoskeleton 90 1815 7 dc torque motor bar linkage hand emg and joint motion hands therapy 91,92 electrical stimulation muscle contraction hand and wrist emg signal hybrid system 93 402 5 linear actuator bar linkage hand emg signal and eeg signal hybrid-driven compliant hand exoskeleton 94 147 dc torque motor cable hand finger torque implanted sensor-controlled microstimulator system 95 electrical stimulation muscle contraction hand and wrist emg signal intfes 96 170 electrical stimulation muscle contraction hand and wrist emg signal intracortical mea-bci-fes 97 electrical stimulation muscle contraction hand and wrist eeg signal (implant) iota 98 230 2 dc servo motors cable hand manual hand layer jamming-based soft tremor suppression glove 34 30 6 dc servo motors hydraulic hand tremor mah system 99 580 6 dc servo motors supernumerary hand wrist angle mahi exo-ii 100,101 340 4 dc motors bar linkage wrist manual selection mecfes 102 2 electrical stimulation muscle contraction hand emg wrist mefes 103 electrical stimulation muscle contraction hand and wrist emg signal mirror hand hs 001 104 800 5 motors bar linkage hand mirrored motion mirror-image motion device with an exoskeleton 105 1800 3 brushless dc motors cable wrist mirrored motion motor orthotic device 106 1 ultrasonic motor gears wrist emg signal mwdo 107 330 2 dc motors bar linkage hand and wrist wrist torque https://doi.org/10.33137/cpoj.v7i1.43827 8 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 table 3 (continued): summary of devices analyzed. device name reference weight of device on arm (g) dof power transmission mechanical transmission hand/ wrist user intent myoelectric control 108 2 electrical stimulation muscle contraction wrist emg myopro 109-112 1814 2 motors direct hand and wrist emg signal nesm and 5-dof wristhand exoskeleton 113 9 dc motors bar linkage hand and wrist joint position ness handmaster system 114-116 electrical stimulation muscle contraction hand manual selection neuro-orthosis 117,118 2 electrical stimulation muscle contraction wrist joint angle nmes-robot arm 119 895 2 dc torque motor muscle contraction and direct wrist emg signal and nmes signal odstock 2-channel programmable stimulator 120 200 electrical stimulation muscle contraction hand and wrist emg signal paediatric hand exoskeleton pexo 45 107 1 linear actuator cable hand and wrist manual hand or hands-free voice control based on keyword detection pinch assistant 121 580 5 dc servo motors pulley hand index and thumb torque pinotti portable robotic exoskeleton ppre 122 1600 2 dc motors gears hand and wrist manual hand pneuglove 123 2 pneumatic actuator pneumatic hand joint angle pneumatic-controlled finger extension system 43 2000* 1 pneumatic actuator pneumatic hand eeg signal power augmentation soft glove 124 120 4 pneumatic actuator mckibben hand joint torque (index) power-assisted fes 125 3 electrical stimulation muscle contraction hand and wrist emg signal reha 2030 126 1 dc motors bar linkage wrist wrist angle and velocity rein-hand system (empi 300 and emg collection unit) 127,128 227 electrical stimulation muscle contraction hand and wrist emg signal relab tenoexo 129,130 148 3 maxon dc motor bowden cable hand finger torque and bend reogo-j 38 79000* 3 motors direct wrist manual selection rope-driven flexible robot 131 linear actuator pulley hand manual selection (touch screen) rupert iv 132,133 5 pneumatic actuator pneumatic wrist joint position and tactile saeboflex and bmr neurotech electrical stimulator unit 134 1587 5 electrical stimulation muscle contraction hand and wrist muscle torque saebomas and accelerometer-triggered fes 135 electrical stimulation muscle contraction hand and wrist joint position script active orthosis sao-i3 136 3 dc motors bar linkage hand and wrist joint angle script1 project 137 elastic torque pulley hand and wrist wrist motion and muscle torque sem glove 138 700 3 brushless dc motors bowden cable hand fingertip tactile semi-soft assistive glove sag 139 2 dc motors cable hand wrist motion and emg sets system 41 255 3 flexible semiactive actuator direct wrist tremor sma muscle 140 300 2 sma hydraulic wrist manual selection https://doi.org/10.33137/cpoj.v7i1.43827 9 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 table 3 (continued): summary of devices analyzed. device name reference weight of device on arm (g) dof power transmission mechanical transmission hand/ wrist user intent snu exo-glove 141 3 brushless dc motors cable hand joint velocity and joint tensile soft glove 142 237 6 pneumatic actuator pneumatic hand and wrist manual selection soft modular elbow-wrist rehabilitation exoskeleton driven by pams 143 2 pneumatic actuator pneumatic wrist joint position soft robotic rehabilitation glove 144 pneumatic actuator pneumatic hand manual selection soft sixth finger 145,146 140 1 dc servo motors supernumerary hand emg softhand x system 147 500 maxon dc motor supernumerary wrist joint angle (finger) sr fingers 148 750 6 dc servo motors supernumerary hand hand position ssvep-bci controlled soft robotic glove rehabilitation system 149 2 pneumatic actuator pneumatic hand eeg signal super stim zzaev906 46 3 electrical stimulation muscle contraction hand and wrist emg signal supernumerary robotic finger srf 44 650 6 dc servo motors supernumerary hand joint angle tcams-exo 150 135 2 dc motors artificial muscle wrist emg and wrist joint angle tdcs 151 electrical stimulation muscle contraction hand and wrist emg signal tds-hm the hand mentor and tongue drive system 152 2 pneumatic actuator pneumatic hand and wrist tongue position tens stimulator n604 153 electrical stimulation muscle contraction hand and wrist emg t-grip exoskeleton 154 50 1 linear actuator bar linkage hand joint angle (wrist) the bionic glove 155 electrical stimulation muscle contraction hand wrist position the hand exoskeleton 156 1800 15 linear actuator push-pull cable hand mirrored motion tiger 157,158 420 2 brushless dc motors bar linkage hand and wrist manual hand (touch screen) upper limb rehabilitation robot 159 6 dc motors gears wrist manual selection utah microelectrode array and nmes 160 6 electrical stimulation muscle contraction hand and wrist eeg signal wdfho 161 1 linear actuator gears hand joint angle (wrist) wearable glove with incorporated compliant mechanical transmission 162 2 pneumatic actuator pneumatic hand manual selection (touch screen) wearable mechanism to suppress axial vibration 36 268 3 dc motors direct wrist tremor wearme glove 163 500 3 brushless dc motors pulley hand and wrist joint angle w-exos 164 1900 3 dc motors gears wrist muscle torque and emg signal whos 165 1 motors bar linkage hand joint angle (wrist) wireless distributed fes system 166 45 electrical stimulation muscle contraction hand emg and joint movement wireless wearable device 167 2 electrical stimulation muscle contraction hand and wrist joint position and movement (wrist) wrist exoskeleton 168 288 2 linear actuator push-pull cable wrist manual selection wrist exoskeleton 169 728 1 dc motors gears wrist mirrored motion x-glove 170 5 linear actuator cable hand manual selection https://doi.org/10.33137/cpoj.v7i1.43827 10 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 recordings on the weight of the device were poor in the literature with only 52% (63/121) mentioning weight. weight spanned from 30g (layer jamming-based soft tremor suppression glove34) to 205kg (armeo power ii50). from the limited reported data, there were indications that the weight of the device on the upper limb was reduced each year on average. the degrees of freedom (dof) were reported in 62% (84/135) of studies and tended to be low, with many devices actuating one (11%, 13/121) or two dof (24%, 29/121). assistive devices which actuated 1 dof had the lowest weight on average at 285g, followed by 6 dof at 422g. devices with higher levels of dof tended to be designed for the hands: average hand device dof was 3.6, whereas wrist devices were 2.8 dof. the categories of mechanical transmission described in table 2, were inspired by bos et al structured overview of dynamic hand orthoses.17 however, this study included muscle contraction and supernumerary devices. this improves the inclusivity of unconventional actuation methods; muscle contraction due to electrical stimulation acts as an internally applied active force, and supernumerary devices use indirect mechanical force to attain adls. muscle contraction (26%, 31/121), bar linkage figure 2: distribution of studies based on the field of outcome measures. 0 5 10 15 20 25 1990 1995 2000 2005 2010 2015 2020 2025 study outcome measures all clinical clinical and technical technical figure 3: count of outcome measures. blue indicates clinical outcomes; orange indicates technical outcomes. the outcome measures in order: rom (range of motion), emg, joint angle, mas (motor assessment scale), fma (fugl-meyer assessment), grasp, arat (action research arm test), force, rmse (root mean square error), joint motion, tasks, grip, torque, pgt (pinch grip test), anova (analysis of variance), arom (active rom), prom (passive rom), bbt (box and blocks test). 0 10 20 30 40 50 60 r o m e m g j o in t a n g le m a s f m a g ra s p a r a t f o rc e r m s e j o in t m o ti o n t a s k s g ri p t o rq u e p g t a n o v a a r o m p r o m b b t f re q u e n c y o f s tu d ie s publication year outcome measure o c c u rr e n c e s o f o u tc o m e m e a s u re https://doi.org/10.33137/cpoj.v7i1.43827 11 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 (15%, 18/121) and pneumatic devices (15%, 18/121) were among the most popular mechanical transmission methods across all applications. to apply the active force, a command signal must be sent to a control unit. this command signal was charted as the “user intent” defined in table 2, results are shown in table 3. the user’s intention to control the device was detected predominantly with electromyography (emg) (30%, 36/121) and users’ joint movement (30%, 37/121). the placement of electrodes for emg varied widely and most emg intention methods were combined with muscle contraction to actuate the upper limb (61%, 22/36), this is the foundation of functional electrical stimulation (fes).171 other user intention methods include detecting a force applied by the joint typically the fingertips, by manually selecting how and when the actuator moves using a touchscreen or joystick, and eeg systems such as the emotiv.65 outcome measures a total of 226 unique outcome measures were extracted from the 765 tests completed in the data set. from the 226 outcome measures extracted, 100 were considered clinical tools using the who-icf model of functional outcomes alongside additional validated sources.10,11,172,173 therefore, 126 outcome measures were considered technical or nonclinical. a dip in the number of clinical-based outcome measures used was found in 2020. while testing of devices on patients had decreased, the past 10 years have seen an exponential increase in research publications on upper limb devices seen in figure 2. the frequency of outcome measures repeated between studies tended to be low (8%, 18/226). the majority of outcome measures appeared in less than 10 studies (92%, 208/226); figure 3 presents the outcome measures most regularly used (outcome measures used in ≥10 studies). the clinical outcome measures trended towards observational ordinal scales inspecting mobility (mas, fma, and bbt) and movement functions (rom, arat and functional tasks). the technical and non-clinical outcome measures were either statistical analysis methods (rmse, anova and kinematic analysis) or usability tests (emg, joint angle, and grasp force of device). patient-reported outcome measures such as the motor activity log (mal), abilhand, disabilities of the arm, shoulder, and hand scale (dash), and quickdash were often under-utilized with 4% use out of all tests extracted (30/765). factors such as introducing variations and modifications in a validation method caused 65% (148/226) of the outcome measurement tools to only be present in the dataset once. another factor increasing the number of unique outcome measures extracted is the use of condition-specific outcome measures such as the stroke impact scale.38,110,134,152 these tailored methods are useful tools to benchmark a person’s functionality within a set population173-176 but make validation across different cohorts difficult as it may not be an appropriate outcome measure for all. technology readiness levels trl 1 (proof of concept studies) and trl 2 (software prototype studies) were not present due to our inclusion criteria provided in table 1. the distribution of all trl extracted can be found in table 4, which also includes the definitions used in the data extraction. overall, trl 6 (21%, 28/135), trl 9 (20%, 27/135) and trl 4 (19%, 26/135) were the most prominent advancement levels. fes (63%, 17/27), emg (44%, 12/27) and devices made to support people with cardiovascular diseases (74%, 20/27) made up most of the technological advancements of trl 9. non-electrical stimulation devices at trl 9 included the myopro,109-112 which uses an emg threshold for control and has been commercialized since 2006, the sem glove,138 reogo-j,38 and armeo power ii.50 of these, sem glove, reogo-j, and armeo power ii were the only trl 9 devices that did not include fes or emg. trends in trl and demographics were also noticed; as the number of participants increases, the trl level improves: case studies (1 participant) were an exemption to this trend. high-income countries also conducted studies at higher trl and there has been a steady development in trl in device testing over the years. devices in category trl 3 were proof of concept (table 4), therefore these studies use analytical or feasibility methodologies. these methods focus on the validation of the device and include only healthy participants. of these trl 3 devices, 47% (8/17) used cable conduit mechanisms, and 29% (5/17) used pneumatic actuation. these devices tended to be designed for supporting the hands (47%, 8/17) and had on average between 2-3 dof. various user detection methods were charted, but manual control of the device was quite frequent in both trl 3 and 9. discussion this study provides an overview of 135 research papers focused on actuated assistive devices for the hand and wrist. a notable result was the scarcity of rigorous clinical methodologies, with 34% (46/135) of studies involving clinical trials, of which 12 studies conducted rcts. from these studies, 121 unique devices were analyzed to scope their intended user populations, design features, validation strategies, and trls. most of the devices were designed for individuals with upper limb impairment due to stroke 46% (597/1310), and a significant proportion of devices had low dof, particularly for wrist devices at an average of 2.8 dof. regarding the design, the devices predominantly utilized emg (30%, 36/121) which tended to be in combination with muscle contraction via electrical stimulation (fes). along https://doi.org/10.33137/cpoj.v7i1.43827 12 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 with emg, user interfaces such as buttons, joysticks, and touch screens were used to detect user intentions. the study categorized a total of 226 unique clinical and technical outcome measures. the validation methods predominantly relied on statistical analyses for technical outcomes, while clinical assessments were often observational. there was a lack of consistency across studies, with many outcome measures used only once (65%, 148/226). objective or patient-reported outcomes were less frequently employed. most of the studies were conducted in high to upper-middleincome economies (90%, 28/31). although the need for assistive technology in low-income countries is high, there may be a lack of awareness and access to actuated devices, contributing to fewer studies conducted in these economies.15,16 low-income economies must often import medical equipment,177 therefore these actuated devices must achieve high trl to be considered for ordering and prescription. yet, these devices have not met trl >6 requirements (76%, 92/121). to fulfil trl >6, the device must meet the iso standards, and regulatory requirements (such as ce marking) before distribution in the market or testing in operational environments (table 4). these conditions provide insurance for device quality, safety and efficiency.178 a few factors which may contribute to these devices not surpassing trl 6 include overcoming the dynamic and rapidly developing policies to meet regulatory requirements for testing,179 a lack of streamlined clinical tests and validation processes for these devices,180,181 and the effects of covid-19 on reduced face-to-face research.182-184 to validate these devices, 226 outcome measurement tools were charted. classification of validation methods showed that 44% (99/226) of the outcome measurement tools were considered clinical; rom, mas and fma were the most used for clinical trials whereas emg, joint angles and device grasp force were conducted in technical studies (figure 2). since many of the devices were designed for stroke rehabilitation (46%, 597/1310), the outcome measures recorded show a strong correlation with existing literature on upper limb outcome measures in stroke recovery.173 patient-reported outcome tests were implemented 4% of the time (30/765). this value is considerably low as these outcomes are invaluable to validate the use of the assistive device.8,173,185 patient-reported outcomes also provide valuable psychometric properties to the evidence base185 and are an important part of upper limb assessment. it should be noted that comorbidities were not often reported, and outcome measures were not standardized, therefore inter-comparability of devices and populations was limited. the lack of inter-comparability was also noticed in the inconsistency in reporting device specifications. dof and weight of the device were not reported routinely (62% and 52% respectively), with some studies quoting their device as “lightweight” without reference to their objective weight. a slight trend toward reducing the weight of upper limb devices over the years was observed, but there is insufficient statistical evidence to support this claim. many devices were designed with low (1 or 2) dof and varied greatly in weight from 33g to 205kg. the variation in weight was due to differences in reporting weight, some studies report weight on the upper limb, while others report weight of the full system. the implication of these differing reporting styles makes synthesizing findings difficult for decisionmaking and provides barriers to further research as the evidence base lacks standardized measures and methods. to improve inter-comparability, frameworks for development can be implemented,186,187 alongside robust and systematic testing using a large cohort.187,188 in line with the works of zhu et al, the field of soft wearable robotics has experienced rapid growth189 as demonstrated by the increasing number of fluidic transmission actuators identified in the study. these fluidic actuators, which include pneumatic and hydraulic, are typically lighter (averaging 234g on the arm) and provide multidirectional force due to their flexible design.190 previous studies have predicted the rise of soft robotics,187 which may continue to improve for use as an actuated assistive device. in addition to fluidic transmission actuators, supernumerary devices (n = 5) have table 4: trl definitions defined by the horizon 2020 work programme 2014-2015 and the scoping review abstraction of the horizon 2020 definitions. trl definition scoping review e planation count 1 basic principle observed the idea has been formulated, proof of concept only 0 2 technology concept formulated a software prototype has been made and tested virtually 0 experimental proof of concept analytical studies and feasibility studies. the device must be built 17 4 technology validated in the lab the device has been tested on non-human or one healthy case study for validation. 26 technology validated in the relevant environment the device has been tested on healthy participants 21 technology demonstrated in the relevant environment the device has been tested on a target population in a clinical setting (iso standard not complete) 29 system prototype demonstration in an operational environment the device has been tested for its intended purpose in an operational environment (outside of the clinic and lab) iso standards should be complete 14 system complete and qualified the device is ready to be commercialized and has been validated 1 9 actual system is proven in an operational environment the device is available in the market 27 https://doi.org/10.33137/cpoj.v7i1.43827 13 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 shown potential for human augmentation.191 however, due to their state-of-the-art nature, the availability of real-world applications and longitudinal evidence supporting their effectiveness is limited.191,192 as these novel actuators continue to advance, future assistive devices should integrate them to improve weight and multifunctionality. to detect a user’s intention, emg (30%, 36/121) and joint movement (30%, 37/121) sensors were regularly implemented. emg control methods, which include surface electrodes, implanted wires, and probes,193 have a long history of use. however, they are not suitable for all individuals with hand and wrist impairment194 and may encounter system failures outside of testing settings.187 emg and joint movement sensors are limited by muscle activation threshold requirements, making them inadequate for addressing the full spectrum of people with upper limb impairment. the prescription of these devices would not be appropriate. consequently, alternative user intention systems were explored including tongue-based interfaces,71,152 hands-free voice control,44 and foot-based interfaces.81 these systems are not limited by upper limb muscle threshold, yet they did not attain trl >6. alongside the requirements for attaining trl >6, design factors may contribute to why these devices are not suitable for operating in a real-world context. wearable sensing and control technology includes various elements which were not abstracted such as cost, consumption and battery lifespan, these may all affect useability.187,195 a systematic analysis of control systems which do not require upper limb muscle activation may be appropriate to validate the use of these underrepresented systems. limitations the results of a scoping review are often quite broad; a synthesis of the conclusions will require additional resources to be used in policymaking. in addition, scoping reviews rarely include critical appraisal of included studies; therefore, the reliability of findings may be skewed. despite this, a scoping review addresses the exploratory nature of upper limb devices compared to other methodologies. in addition, as with many studies, the design of this study is subject to limitations. these concerned the selection of studies, definitions of terms during screening and the exclusion of data charting items. due to time constraints, this study did not screen all forms of grey literature such as market reports, patents or working papers, and the keyword selection may have excluded appropriate studies. in addition, 118 studies were not retrieved (figure 1) due to restricted access to certain relevant research papers. this limitation arose primarily due to paywalls and institutional access restrictions. this introduced selection bias and may have hindered the scope and number of devices investigated with higher technological readiness levels. during the screening process, the reviewers ultimately agreed on a consensus with 86.9% accuracy, but the definition of portable was defined as easily moveable by healthy users. this meant results on the weight of the device had large variability. this limitation was somewhat mitigated by recording the device's weight on the arm, although some studies only reported the total weight of the device. this study did not chart how the device interacts with the user’s joint-segment, such as enabling voluntary hand-opening or supporting wrist flexion. this data charting item would have provided more context for the device's functions. conclusion active, actuated assistive devices offer promising solutions to improve functionality and quality of life for individuals with hand impairments. this study reviews 135 studies covering 121 devices, providing insights into actuated devices for hand and wrist support in adls. innovation in actuation systems and control methods is evident, yet many devices have not advanced beyond trl 7, highlighting the gap between research and market-ready products. emg and fes systems dominate the field but may not be suitable for users with limited muscle activation, showing the need for alternative approaches such as tongue interfaces and voice control systems. key barriers to prescription included insufficient real-world evidence, concentration of development in highand middle-income countries, lack of standardized reporting, and the absence of accepted clinical validation processes. to overcome these challenges, it is essential to establish standards for device design, testing, and reporting (e.g., weight, degrees of freedom), develop comprehensive outcome measures combining objective methods with patient-reported experiences, and improve the accessibility of devices in low-income countries. the field of hand and wrist exoskeletons shows increased popularity in the innovation of control systems and actuators. addressing these challenges and implementing standardized frameworks will help improve the prescription of these devices. as technology advances, tailored solutions for individuals with varying levels of hand functionality are becoming increasingly feasible, offering significant benefits to those with upper limb impairments. overall, there is promise and growth in the field of hand and wrist exoskeletons. acknowledgements we would like to acknowledge the funding and support from the university of strathclyde and the uk engineering and physical sciences research council (ep /s02249x). declaration of conflicting interests the authors declare no conflict of interest. https://doi.org/10.33137/cpoj.v7i1.43827 14 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; 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10.1142/s0219519422400437 132.balasubramanian s, wei hr, perez m, shepard b, koeneman e, koeneman j, et al. rupert: an exoskeleton robot for assisting rehabilitation of arm functions. virtual rehabil. 2008;163-167. doi: 10.1109/icvr.2008.4625154 133.he j, koeneman ej, schultz r, herring d, wanberg j, huang h, et al. rupert: a device for robotic upper extremity repetitive therapy. ieee eng med biol 27th ann conf. 2005;6844-6847. doi: 10.1109/iembs.2005.1616077 134.butler a, blanton s, rowe v, wolf s. attempting to improve function and quality of life using the ftm protocol: case report. j neurol phys ther. 2006;30(3):148-156. doi: 10.1097/01.npt. 0000281952.93934.6b 135.meadmore kl, exell ta, hallewell e, hughes am, freeman ct, kutlu m, et al. the application of precisely controlled functional electrical stimulation to the shoulder, elbow and wrist for upper limb stroke rehabilitation: a feasibility study. j neuroeng rehabil. 2014;11(1). doi: 10.1186/1743-0003-11-105 136.ates s, 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strategies for lower-limb exoskeletons to assist gait. j neuroeng rehabil. 2021;18(1):119. doi: 10.1186/s12984-021-00906-3 list of abbreviations acronym definition adl activities of daily living aha assisting hand assessment ahp allied health professional amea absolute mean error analysis ancova analysis of covariance anova analysis of variance aou amount of use arat action research arm test ari active resistance index arom active range of motion asia american spinal injury association (asia) impairment scale bbt box and block test bi barthel index bmrc british medical research council scale cgi clinical global impression chedocke chedocke mcmaster hand portion cmc coefficient of multiple correlation cmsa chedocke-mcmaster stroke assessment copm canadian occupational performance measure cts carpal tunnel syndrome cue-t capabilities of upper extremity test cva cerebral vascular accident dmd duchenne muscular dystrophy dof degree of freedom donn/doff putting on and removing task d-quest dutchquebec user evaluation of satisfaction with assistive technology dtm dart throwing motion dtsam dynamic traction splint by artificial muscle eeg electroencephalogram emg electromyography fat the frenchay arm test fea finite element analysis fes functional electrical stimulation fim function independence measurement fma fugl-meyer assessment https://doi.org/10.33137/cpoj.v7i1.43827 https://hermanwallace.com/download/the_abc_of_emg_by_peter_konrad.pdf https://hermanwallace.com/download/the_abc_of_emg_by_peter_konrad.pdf https://www.ijser.org/researchpaper/trends-and-challenges-in-emg-based-control-scheme-of-exoskeleton-robots-a-review.pdf https://www.ijser.org/researchpaper/trends-and-challenges-in-emg-based-control-scheme-of-exoskeleton-robots-a-review.pdf https://www.ijser.org/researchpaper/trends-and-challenges-in-emg-based-control-scheme-of-exoskeleton-robots-a-review.pdf 22 galbert a, buis a. active, actuated, and assistive: a scoping review of exoskeletons for the hands and wrists. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.9. https://doi.org/10.33137/cpoj.v7i1.43827 canadian prosthetics & orthotics journal issn: 2561-987x a scoping review of exoskeletons for the hands and wrists galbert a, and buis a, 2024 fmri functional magnetic resonance imaging gain global appraisal of individual needs grassp graded redefined assessment of strength, sensibility and prehension grt grasp and release test ibep integral value of a bioelectric potential imu inertial measurement units iota isolated orthosis for thumb actuation irq interquartile range jthft jebson taylor hand function test kinarm kinesiological instrument for normal and altered reaching movement lgmd limb girdle muscular dystrophies mal motor activity log manova multivariate analysis of variance mapr multi-attribute preference response marat modified action research arm test marp mean arrest period ratio mas modified ashworth score mav mean absolute value mdc minimal detectable change mes mean error squared mmse mini-mental state examination mmt manual muscle testing movement abc movement assessment battery for children mpf mean power frequency mppt modified purdue pegboard test mvc maximum voluntary contraction nasa-tlx the nasa task load index nhpt nine hole peg test nihss national institute of health stroke scale nsa nottingham sensory assessment pcgi-i patient clinical impressions-improvements piads psychosocial impact of assistive devices scale prismascr the preferred reporting items for systematic reviews and meta-analysis extension for scoping reviews prom passion range of motion prs pain assessment rating scale pul performance of the upper limb scale qif-sf quadriplegia index of function-short form qol quality of life qom quality of movement scale quest quebec user evaluation of satisfaction with assistive technology quickdas h quick disabilities of the arm, shoulder, and hand questionnaire rct randomized control trial rma rivemead motor assessment rmsd root means square difference rmse root means square error rmsed root mean standard error of deviation rom range of motion rtlx raw nasa-task load index sal spectral arc length scim-sr spinal cord independence measure–self-report semg surface electromyography seps somatosensory evoked potentials sias stroke impairment assessment set sis stroke impact scale sus system usability scale swmt semmes-weinstein monofilament test tam total active motion tbi traumatic brain injury tlt thumb localizing test tri-hft toronto rehabilitation institute hand function test trl technology readiness level udq use of device questionnaire use the usefulness-satisfaction-and-ease-of-usequestionnaire vas visual analog pain assessment scale who-icf world health organisation the international classification of functioning, disability and health wilco on test the wilcoxon signed-rank test wmft wolf motor function test https://doi.org/10.33137/cpoj.v7i1.43827 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 1 2024 professional opinion alam j, joshi a, mir n, chawla n, sagar s. invisible struggles: exploring challenges faced by women with amputation in india. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.5. https://doi.org/10.33137/cpoj.v7i1.44002 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i1.44002 1 alam j, joshi a, mir n, chawla n, sagar s. invisible struggles: exploring challenges faced by women with amputation in india. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.5. https://doi.org/10.33137/cpoj.v7i1.44002 professional opinion invisible struggles: exploring challenges faced by women with amputation in india alam j1, joshi a1, mir n1, chawla n2, sagar s1* 1. division of trauma surgery and critical care, jai prakash narayan apex trauma centre, all india institute of medical sciences, new delhi, india. 2. department of psychiatry, all india institute of medical sciences, new delhi, india. the 2019 global burden of diseases (gbd) report highlighted that india sees about 23,500 new cases of people with amputation each year, with men making up the majority—around 20,200—while approximately 3,300 are women.1 older women, especially those over 70, are at a heightened risk for traumatic amputations due to osteoporotic changes, according to gbd data.2 however, in our population, road traffic injuries (rtis) emerge as the leading cause of amputations, followed by train-associated injuries, attributed to lax laws and an increasing population.3 additionally, gender plays a role in prosthetic access and fitting, as fewer women (42.9%) successfully receive prosthetic limbs upon discharge compared to men (68.6%).4 this disparity may stem from concerns related to the appearance of the prosthesis and its bulkiness. in patriarchal societies like india, there is often a tendency to prioritize men's comfort over women's needs, which can result in the dismissal of women's genuine concerns as "emotional" or "natural phenomena”.5 this societal bias may contribute to higher prosthesis rejection rates among women as compared to men. additionally, women with disabilities face a dual form of discrimination—one based on gender and the other on their physical disability. this discrimination, combined with lower literacy rates, significantly reduces their job opportunities.6 the lack of empathy in indian society towards individuals with disabilities is not a secret, especially if they are women, it creates a sense of insecurity in them about their future. they often fear abandonment by their husband or in-laws or have negative views on marriage prospects. in some instances, parents of unmarried daughters do not consent for amputation fearing their uncertain future. consequently, women with amputations are seen as a "burden," making them more vulnerable than both able-bodied women and disabled men. disability can either cause or result from poverty, creating a vicious cycle that is further exacerbated by stigma and the denial of basic rights and opportunities, particularly for women.1 in india, only a handful of organizations such as those supported by the ministry of social justice and empowerment and ministry of women and child development under the government of india offers prosthetic devices at little or no cost to support individuals with disabilities. however, these prosthetic devices are often bulky, outdated in technology, and not well-suited to women needs.7 apart from this, factors such as frequent volumetric changes in the residual limb, patient’s age, comorbidities, and the level of amputation often contribute to the rejection of prosthetic devices. moreover, the side of the amputation can also play a role in this rejection, especially if it involves the dominant side, which is more relevant in case of upper extremity amputation. this can lead to a diminished sense of body perception, which significantly impacts performance, making individuals open access abstract women in india, particularly those with amputation, face significant challenges, including but not limited to, unequal prosthetic access and satisfaction, societal discrimination, and the physical and emotional consequences of amputation. these challenges are further exacerbated by gender biases towards access to education and socioeconomic factors, which increases their vulnerability to unemployment and mental health issues. this article emphasizes the urgent need for affordable and customizable prosthetic options tailored to the unique needs of women with amputation, particularly those from low-income backgrounds who often face neglect. thus, addressing these disparities would significantly enhance their overall well-being and independence. article info received: september 19, 2024 accepted: october 10, 2024 published: october 14, 2024 citation alam j, joshi a, mir n, chawla n, sagar s. invisible struggles: exploring challenges faced by women with amputation in india. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.5. https://doi.org/10.33137/cpoj.v7i1.44002 keywords amputation, rehabilitation, india, women with amputation, prosthesis, prosthetics, quality of life, satisfaction, disability * corresponding author: professor sushma sagar, division of trauma surgery and critical care, jai prakash narayan apex trauma centre, aiims, new delhi, india. e-mails: sagar.sushma@gmail.com; dr.sushma@aiims.gov.in orcid id: https://orcid.org/0000-0002-4700-9868 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 1, article no.5. 2024 https://doi.org/10.33137/cpoj.v7i1.44002 https://doi.org/10.33137/cpoj.v7i1.44002 mailto:sagar.sushma@gmail.com mailto:dr.sushma@aiims.gov.in https://orcid.org/0000-0002-4700-9868 https://jps.library.utoronto.ca/index.php/cpoj/index 2 alam j, joshi a, mir n, chawla n, sagar s. invisible struggles: exploring challenges faced by women with amputation in india. canadian prosthetics & orthotics journal. 2024; volume 7, issue 1, no.5. https://doi.org/10.33137/cpoj.v7i1.44002 canadian prosthetics & orthotics journal issn: 2561-987x challenges faced by women with amputation in india alam et al., 2024 slower and more self-conscious while limiting their overall function.8 moreover, in india, women from low socioeconomic backgrounds frequently engage in physically demanding jobs, such as domestic work, agriculture, and manual labour, which necessitate floor sitting, mobility, and stamina. unfortunately, the affordable prosthetic options available to these women often fall short in providing the functionality required for these strenuous tasks. this inadequacy can lead to feelings of frustration, disappointment, and various health issues. the literature on people with amputation revealed that they often experience anxiety, depression, and post-traumatic stress disorder. however, women are particularly more vulnerable to depression following an amputation than men. if the amputation involves the upper limb, this risk doubles for women, as the upper limb is crucial for self-expression, self-care, and communication, leading to a greater functional loss compared to lower limb amputations. moreover, if depression is diagnosed, the likelihood of unemployment increases tenfold. even though men are more frequently subjected to amputations, women generally experience worse outcomes.9-11 to address the specific challenges that women face in india, it is essential to provide affordable yet customizable prosthetic solutions that can support their unique physically demanding work schedules. the low-cost customizable prosthetic devices need to be less bulky and comparatively less in weight for improved functionality. a recent innovation by a prestigious indian institute offers a high-end prosthetic feature of cross-legged sitting in a low-cost above-knee prosthesis, holds promise in addressing this gap by not only making them independent but also allowing them to perform long periods of sitting, standing, or squatting, that are typically seen as a royalty for a non-affording person with amputation.12 furthermore, adopting a user-centered design approach that takes into account the experiences of women with amputations during the customization process can highlight essential details that might otherwise be missed. a more secure and snug-fitting suspension that minimizes bulkiness would also be particularly attractive from a cosmetic perspective for women. additionally, addressing specific needs related to menstrual hygiene or pregnancy is vital, especially for those with higher levels of lower limb amputation where the proximal brim of the socket is a problem. consequently, providing well-fitted and functional prosthetics is the way of empowering women, enhancing their physical and mental well-being, and reducing disparities in access to prosthetic use. this enables them to lead active, dignified lives, irrespective of their economic status or disability. declaration of conflicting interests the authors have no conflicts of interest to disclose. the manuscript has been read and approved by all the authors. sources of support none. references 1.mishra s, kumar d, gupta ak, yadav g, ghosh s. a demographic study of lower limb people with amputation in a north indian tertiary rehabilitation center. indian j phys med rehabil. 2020;31(1):11–3. doi: 10.5005/jp-journals-10066-0066 2.yuan b, dong h, gu s, xiao s, song f. the global burden of traumatic amputation in 204 countries and territories. front public health. 2023;11. doi: 10.3389/fpubh.2023.1258853 3.dar pmud, mir n, katiyar ak, sati hc, priyadarshini p, alam j, et al. outcome predictors of patients who underwent limb amputation/s following trauma at a level i trauma center in north india. eur j trauma emerg surg. 2024;50(1):233-242. doi: 10.1007/s00068-023-02273-1 4.singh r, hunter j, philip a, tyson s. gender differences in amputation outcome. disabil rehabil. 2008;30(2):122–5. doi: 10.1080/09638280701254095 5.women’s pain is often not believed – here’s how to make your voice heard when seeking help [internet]. hindustan times. 2023 [cited 2024, sep 19]. available from: https://www.hindustantimes.com/lifestyle/health/women-pain-isoften-not-believed-here-s-how-to-make-yourvoice-heard-whenseeking-help-101694585279987.html 6.perkins zb, de’ath hd, sharp g, tai nrm. factors affecting outcome after traumatic limb amputation. br j surg. 2011;99(s1):75–86. doi: 10.1002/bjs.7766 7.not as good as real, but new prosthetics give confidence to live independent lives [internet]. the times of india. 2023; [cited 2024, sep 19]; available from: https://timesofindia.indiatimes.com/city/delhi/not-as-good-asrealbut-new-prosthetics-give-confidence-to-live-independentlives/articleshow/97210838.cms 8.nico d. left and right hand recognition in upper limb amputees. brain. 2004;127(1):120–32. doi: 10.1093/brain/awh006 9.kashani jh, frank rg, kashani sr, wonderlich sa, reid jc. depression among people with amputation. j clin psychiatry. 1983;44(7):256-8. 10.cheung e, alvaro r, colotla va. psychological distress in workers with traumatic upper or lower limb amputations following industrial injuries. rehabil psychol. 2003;48(2):109–12. doi: 10.1037/00905550.48.2.109 11.hirsh at, dillworth tm, ehde dm, jensen mp. sex differences in pain and psychological functioning in persons with limb loss. j pain. 2010;11(1):79–86. doi: 10.1016/j.jpain.2009.06.004 12.iit guwahati creates affordable prosthetic leg for indians that allows deep squatting, cross-legged sitting [internet]. india today. 2022 [cited 2024, sep 19]. available from: https://www.indiatoday.in/education-today/news/story/iit-guwahaticreates-affordable-prosthetic-leg-for-indians-that-allows-deepsquatting-cross-legged-sitting-1965024-2022-06-21 https://doi.org/10.33137/cpoj.v7i1.44002 https://www.hindustantimes.com/lifestyle/health/women-pain-is-often-not-believed-here-s-how-to-make-your-%20voice-heard-when-seeking-help-101694585279987.html https://www.hindustantimes.com/lifestyle/health/women-pain-is-often-not-believed-here-s-how-to-make-your-%20voice-heard-when-seeking-help-101694585279987.html https://www.hindustantimes.com/lifestyle/health/women-pain-is-often-not-believed-here-s-how-to-make-your-%20voice-heard-when-seeking-help-101694585279987.html https://timesofindia.indiatimes.com/city/delhi/not-as-good-as-%20real-but-new-prosthetics-give-confidence-to-live-independent-lives/articleshow/97210838.cms https://timesofindia.indiatimes.com/city/delhi/not-as-good-as-%20real-but-new-prosthetics-give-confidence-to-live-independent-lives/articleshow/97210838.cms https://timesofindia.indiatimes.com/city/delhi/not-as-good-as-%20real-but-new-prosthetics-give-confidence-to-live-independent-lives/articleshow/97210838.cms https://www.indiatoday.in/education-today/news/story/iit-guwahati-creates-affordable-prosthetic-leg-for-indians-that-allows-deep-squatting-cross-legged-sitting-1965024-2022-06-21 https://www.indiatoday.in/education-today/news/story/iit-guwahati-creates-affordable-prosthetic-leg-for-indians-that-allows-deep-squatting-cross-legged-sitting-1965024-2022-06-21 https://www.indiatoday.in/education-today/news/story/iit-guwahati-creates-affordable-prosthetic-leg-for-indians-that-allows-deep-squatting-cross-legged-sitting-1965024-2022-06-21 volume 6, issue 2 2023 articles in this special issue has been invited and reviewed by dr. silvia ursula raschke and dr. hossein gholizadeh. d e s i g n i n g t h e f u t u r e : 3 d p r i n t i n g ' s r e v o l u t i o n i n p r o s t h e t i c s & o r t h o t i c s s t a k e h o l d e r p e r s p e c t i v e s printing 3d publisher: canadian online publication group s p e c i a l i s s u e cpoj issn: 2561-987x https://jps.library.utoronto.ca/index.php/cpoj/editorinchief 1 efstathiou k, mcgarry a. 3d printed cosmetic covers for lower limb prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.8. https://doi.org/10.33137/cpoj.v6i2.42176 stakeholder perspectives 3d printed cosmetic covers for lower limb prosthetics efstathiou k1, mcgarry a2* 1 orthodesigns, giannou kranidioti, limassol, cyprus. 2 department of biomedical engineering, university of strathclyde, glasgow, uk. introduction prosthetic users make use of lower limb prosthetics in their everyday life to complete tasks that they could do before their amputation. even though a prosthesis may provide a wide variety of functional benefits, many patients choose to reject all these benefits over a poor cosmetic appearance.1 therefore, the patient's body image may be a crucial aspect to consider when prescribing a prosthesis. poor cosmetic appearance may consist of factors such as bulky interface materials; abnormal appearance of the suspension system below clothes and/or lack of anatomical symmetry.2 conversely, a good cosmesis may assist prosthetic acceptance; promote functional recovery; positively affect outcome measures and improve self and social acceptance of the patient.2 although cosmetic appearance constitutes a huge factor in the patients’ lives, the available literature regarding cosmetic covers is limited. in the current study, major companies who produce cosmetic covers on a commercial scale were identified. furthermore, each company’s cover design was briefly outlined, and a list of criteria was developed. moreover, all designs were compared in a pairwise fashion based on these criteria and a theoretical novel design was then presented utilising the highest performing criteria to create an improved design. traditionally, cosmetic covers focused on achieving the best aesthetic appearance possible, mirroring the image of the patient’s sound leg. through time, a fresh perspective has developed on cosmetic appearance where the traditional/realistic covers have evolved into a more creative product, transforming the concept of disability into a concept of super-ability, promoting the user’s personality.3 studies have revealed that about 60% of prosthetic users were neutral or dissatisfied with traditional designs, resulting many companies to divert into new manufacture technologies.4 companies are now able to produce custom made covers on a commercial scale, encouraging users towards personalised covers which truly reflect their personality and do not necessarily need to represent a natural look. there are many ways to produce a lower limb cosmetic cover. most prosthetists historically used a plastazote foam block, which was then shaped and matched to the patient's sound leg to provide a more cosmetic appearance of the prosthesis.2 although foam covers have been an affordable open access abstract cosmetic covers provide better aesthetic appearance and may facilitate increased acceptance of the prosthesis. traditionally, cosmetic covers aimed to achieve an aesthetic and realistic appearance; through time, a fresh perspective has developed on cosmetic covers where traditional/realistic covers evolved into a custom-made product, which truly promotes the patient’s personality. the objectives of the study were to gather information from five well-known companies in the cosmetic cover industry (unyq, limb-art, alleles, willowwood and aqua-leg), analyse and compare their design elements using the pugh matrix, and suggest a novel design using the best performing criteria of each design. the overall results of the pugh matrix revealed the opportunity of a new design with improved design elements mainly in terms of “cover fit/aesthetics”, “ease of attachment” and “practicality”. the novel design had a vast difference in total score from the second-best design, revealing the improvement possibilities such cover design may have in the future. although the study successfully presented a theoretical novel design, it was based on data found through literature and web resources, making the overall results of the study more objective rather than subjective. future research is encouraged to be conducted based on a more subjective approach towards cosmetic covers. citation efstathiou k, mcgarry a. 3d printed cosmetic covers for lower limb prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.8. https://doi.org/10.33137/cpoj.v6i2.4 2176 keywords cosmetic cover, aesthetic covers, lower limb, artificial limb, amputation, prosthetics, additive manufacturing, 3d printing * corresponding author: anthony mcgarry, phd department of biomedical engineering, university of strathclyde, glasgow, uk. e-mail: anthony.mcgarry@strath.ac.uk orcid id: https://orcid.org/0000-0002-0738-5906 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 6, issue 2, article no.8, 2023 special issue https://doi.org/10.33137/cpoj.v6i2.42176 https://doi.org/10.33137/cpoj.v6i2.42176 https://doi.org/10.33137/cpoj.v6i2.42176 mailto:anthony.mcgarry@strath.ac.uk https://orcid.org/0000-0002-0738-5906 https://jps.library.utoronto.ca/index.php/cpoj/index 2 efstathiou k, mcgarry a. 3d printed cosmetic covers for lower limb prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.8. https://doi.org/10.33137/cpoj.v6i2.42176 canadian prosthetics & orthotics journal issn: 2561-987x 3d printed cosmetic covers for lower limb prosthetics efstathiou k, and mcgarry a, 2023 (special issue) and lightweight option, they may be highly disadvantageous on the aspects of durability and customisation. technological advancements have facilitated companies to move into injection moulding techniques, to produce more durable, detailed, and water-resistant silicone covers.5,6 recently, 3d printing technologies have been introduced in the industry, making cosmetic covers fully customisable, whilst affordable. additive manufacturing, of which the most known form is 3d printing, combines a group of emerging and innovative techniques to produce covers based on digital models using a layer-by-layer accumulation approach.7 the most common techniques are multi jet fusion (mjf) and selective laser sintering (sls); both are powder bed fusion (pbf) based techniques that use nylon powder/polyamide to produce the covers. the main difference between these techniques is that sls uses a co2 laser as a heat source, where mjf utilises an array of infrared lamps as a heat source along with a fusing agent that absorbs infrared radiation energy. mjf also uses a water-based detailing agent to inhibit the powder's fusion near the part edges, which enhances the overall cover’s quality.8 sls has generally been used more, as it was initially developed during the 1980s, where mjf is a more recent technique emerging in 2014. a recent study,8 having analysed and compared these two methods, concluded that mjf printed samples presented better printing quality and stronger bonding strength between layers; mjf samples also had higher tensile and flexural strength with a better surface finish compared to the sls samples. schematic illustration of the two pbf processes can be found in cai et al., recent publlication.8 manufacture of cosmetic covers has been becoming more exciting and creative over recent years, as many companies utilised these production methods. some of the most wellknown companies in the cosmetic cover industry are unyq, limb-art, alleles, willowwood and aqua-leg. the selection procedure aimed to include companies involved in all three types of manufacture methods; foam, silicone and 3d printed. initially, many companies that produce foam covers were identified, but willowwood was chosen amongst them as it provided adequate information about their covers. furthermore, ottobock company was the most popular amongst the production of silicone covers, but there was insufficient information about their covers which resulted in choosing the next available candidate, aqua-leg. the rest of the companies, unyq, limb-art and alleles, were some of the few companies who provided custom made covers and were termed as appropriate for this study. the objectives of the current study were to gather information from these five well-known companies in the cosmetic cover industry, analyse and compare their design elements using the pugh matrix, and suggest a novel design using the best performing criteria of each design. methodology following the analysis of the five different designs, a pugh matrix was used to compare them with each other and produce a theoretical novel design. the pugh matrix is a diagram that allows to make a pairwise comparison between several designs against a set of criteria and then decide which design meets best these criteria. it also allows a degree of qualitative optimisation of the designs through the generation of new designs. one of the most important aspects of a pugh matrix is to correctly identify the criteria, as the robustness and validity of the outcome is fundamentally dependent on an appropriate set of criteria.9 criteria selection was based upon factors considered important in evidence-based literature and from websites themselves. cosmetic appearance and fit of the cover have been an essential factor for prosthetic users; therefore, the first and one of the most important criteria was “cover fit/aesthetics”, which appraised the cover's cosmetic appearance and fit on the prosthesis. cosmetic appearance was evaluated more towards the design's artistic and creative side and not the realistic/natural look. as prosthetic users already have high expenses regarding the prosthesis, liners, etc., the cover's cost was an essential factor that a prosthetic user may consider before buying the cover.2 consequently, the second criterion was “economical” and referred to the cover’s price. “lightweight” has been set as the third criterion and appraised the weight of each cover. the cover’s weight may be a crucial factor for some patients, as extra weight increase stresses between joint surfaces and skin.10 the durability of the cover was considered as an important factor, especially for active walkers.4 the criterion of “durability” was about the cover’s robustness and strength under low/medium impacts. the next very important criterion was “maintenance/ repair” which referred to the maintenance, if any was required; the repairability of the cover, if it gets damaged; and if any warranty was available with the cover. prosthetic users have considered maintenance, repairability and warranty as an important aspect of a cosmetic cover.4 moreover, the next two criteria were “ease of attachment” and “practicality”. ease of attachment was simply referring to the attachment method and how easy it is to don and doff the cosmetic cover, which is very important from the user’s perspective. practicality was about when alignment changes were applied on the prosthesis and if the cover was still usable and cosmetically acceptable after these changes. this criterion was considered as significant, as the overall cosmetic appearance may be affected due to the low practicality of a cover. https://doi.org/10.33137/cpoj.v6i2.42176 3 efstathiou k, mcgarry a. 3d printed cosmetic covers for lower limb prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.8. https://doi.org/10.33137/cpoj.v6i2.42176 canadian prosthetics & orthotics journal issn: 2561-987x 3d printed cosmetic covers for lower limb prosthetics efstathiou k, and mcgarry a, 2023 (special issue) the next criterion was “customisation” and referred to the customisation options available for each design. a variety of customisation options allowed users to choose a cover which truly reflects their personality. therefore "customisation" was an important criterion to include. the last five criteria were “ease of cleanliness”, “insurance”, “protection”, “clear website instructions” and “reliability”. ease of cleanliness was about how easy it is to clean the cover for the user.4 insurance evaluated if the cost of the cover will get reimbursed or not, by an insurance company. this criterion was directly related and was equally important to the “economical” criterion, as if the cover was overpriced, then the chances for compensation by the insurance company were low. next, the criterion of “protection” assessed the level of protection a cover provided to the expensive prosthetic components, which was an important factor to consider. second to last, the criterion “clear website instructions”, evaluated how clear were the website instructions given by the company to the user and prosthetist, about the use and maintenance of their cosmetic cover. lastly, the criterion of “reliability” addressed whether the company or prosthetist could deliver a cosmetic cover that seamlessly fits the user every time. once an appropriate set of criteria have been identified, the willowwood foam cover was selected as the baseline, where all criteria for this design were marked with the letter “s”. willowwood was the most appropriate candidate to be set as the baseline since this type of design was the most well-known amongst the profession of prosthetics. next, all other candidate designs were compared in a pairwise fashion against the baseline for each of the criteria and marked accordingly following the marking rational specified in table 1.9 table 1: marking rational for a pugh matrix. the overall evaluation was made by adding the “+” and “-” for each design concept. baseline candidate design symbol used s better + s much better ++ s worse s much worse - s equal s to help discriminate the options even more, the criteria have been also weighted. although there was no change in the rankings after applying the weightings, it was useful in deciding which design elements were the best to include in the new design. results after the evaluation of the five designs, willowwood was placed last (table 2). although the total score was the lowest amongst the other covers, it was equal or better at the criteria of “economical”; “lightweight” and “insurance”; making it the most suitable option for the buyer who requires a low-cost cover with relatively aesthetic appearance. the alleles design outperformed the rest of the designs in the following criteria: “lightweight”; “maintenance/repair”; “practicality” and “clear website instructions”. covers produced by alleles were the most lightweight starting from 150g, where other covers started from 250g or more (250g>x>700g). the willowwood foam covers weighted approximately the same as the alleles design but scored negatively and lowest in most of the other criteria and therefore is considered the least appropriate. alleles also provided the ability to prosthetists to adjust or modify the shape of the cover after delivery, with the use of a heat gun. this option may be very useful in case of any minor damages to the cover or when the prosthetist needs to make major alignment changes to the prosthesis which may affect the cosmetic appearance of the cover. it also provided the most straightforward website instructions for both user and prosthetist on how to fit and take care of the cover after delivery. table 2: pugh matrix evaluation. design concepts evaluation criteria w e ig h t in g s o f c r it e r ia w il l o w w o o d f o a m c o v e r a q u a -l e g u n y q l im b -a r t a l l e l e s n o v e l d e s ig n cover fit/aesthetics 5 s ++ ++ + + ++ economical 5 s ---- lightweight 2 s --s s durability 4 s + ++ ++ ++ ++ maintenance/repair 3 s + + + ++ ++ ease of attachment 2 s s ++ + + ++ practicality 3 s s + + ++ ++ customisation 4 s + ++ ++ ++ ++ ease of cleaniness 3 s ++ ++ ++ ++ ++ insurance 3 s -s protection 2 s + ++ ++ ++ ++ clear website instructions 3 s s + + reliability 4 s ++ ++ s + ++ total + 0 10 16 12 16 19 total 0 7 5 3 3 3 total score 0 3 11 9 13 16 weighted total + 0 37 54 39 52 63 weighted total 0 23 17 10 13 13 weighted score 0 14 37 29 39 50 https://doi.org/10.33137/cpoj.v6i2.42176 4 efstathiou k, mcgarry a. 3d printed cosmetic covers for lower limb prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.8. https://doi.org/10.33137/cpoj.v6i2.42176 canadian prosthetics & orthotics journal issn: 2561-987x 3d printed cosmetic covers for lower limb prosthetics efstathiou k, and mcgarry a, 2023 (special issue) discussion the three main manufacture methods and five well-known companies that produce commercially cosmetic covers were identified. after a thorough description of each company’s cosmetic cover, a pairwise comparison was conducted using a pugh matrix based on the criteria defined by the researcher. the results of the pugh matrix let to consider a novel design utilising the best performing criteria from the other candidate designs. the new design concept revealed the opportunity of an improved design by pointing out some of the key design elements that could be included in a new design. in addition, the new design scored a much higher total score when compared to the second-best design (alleles), hence identifying once again the improvement possibilities such cover design may have in the future. novel design following the application of the weightings (table 2), the two leading design concepts, unyq and alleles, scored almost the same. although both designs had almost an identical total score, the two designs outperformed each other in different design elements, which let to consider creating a new and superior design. combining the most appropriate design elements together in a novel design, resulted to a higher total score (50 points) when compared to all the other design concepts (table 2). this is a theoretical novel design but considering that these companies already produced and tested their covers, it can be assumed that the production of such design is feasible. the novel design was described in the next section while following a logical order from table 2. starting with the criterion of “cover fit/aesthetics”; 3d scanning technology should be used to capture the true image of the patient’s prosthesis and sound leg to establish a perfect fit for the cover. the cost of the cover should be as affordable as possible, but possibly a high price tag is inevitable as the most advanced materials and scanning techniques are meant to be used in the production of such design. an “attractive” price range for the novel design would be between $500 and $1000, although this is influenced by many factors during the production phase. reducing the cost of the cover will increase the possibilities for the insurance companies to reimburse the cover and may attract more users to buy and try the cover. unfortunately, no previous studies nor web resources have stated an absolute range of prices an insurance company would reimburse. ideally the cover should be lightweight and still durable enough to resist impacts and protect the prosthetic componentry, which can be achieved using the mjf 3d printing method and high-grade nylon powder as the material of the cover. in cases of any major damages to the cover, a replacement policy should be provided to the users. moreover, one of the attachment methods should be with magnets as this may be the fastest way to don and doff the cover. for the criterion of “practicality”, the cover should be able to be “fine-tuned” to any alignment changes made on the prosthesis which may affect the overall shape; this may be achieved with the use of a heat gun, or with a “flexible” cover design consisting of different moving parts or auxetic structures allowing the cover to adjust in any alignment and volume changes. the cover’s design and colours should be fully customisable to match the patient’s needs. pugh matrix evaluation to better appreciate the rationale behind the score of each design concept, the first three rows of table 2 have been briefly explained. beginning with the first row which refers to the criterion of “cover fit/aesthetics”. the willowwood foam cover, which was set as the baseline, can be described as un-cosmetic around the knee joint, and can change shape over time; in addition, foam covers may not always represent a true mirrored image of the sound leg. based on the performance of the baseline, unyq and aqua-leg scored “++”, as their covers perfectly fit on the prosthesis due to the 3d scanning technology used, where the margin of error is minimal. lastly, limb-art and alleles scored “+”, as they both use manual measuring procedures to manufacture their covers, but they still produce more aesthetic covers than the baseline. moving on to the second and third rows, which refer to the criteria of “economical” and “lightweight”. the willowwood foam cover cost less than $100 and weighs around 150g.11 for the “economical” criterion, all other candidates scored worse than the baseline; for instance: limb-art scored “-” because their cheaper cover starts from $27012 and unyq scored “--” because their cheaper cover starts from $495.13 for the “lightweight” criterion, all the covers, except alleles, scored worse than the baseline; for instance: unyq scored “--” because their lighter cover weighs 300g,14 which was heavier than the baseline; thus, the negative score. the most lightweight alleles cover weighs 150g,15 which was approximately the same as the baseline; therefore, the letter “s” was used. study limitations the information for each company's cosmetic cover were mainly gathered from their websites which may have influenced the data's reliability as it may be biased in some sections; this approach was used due to lack of available published literature about each cover. whilst the criteria set on this study were thought to be inclusive of the main factors which should be considered in the design of a cosmetic cover, they are not exhaustive. it is feasible that alternative criteria could be selected and prioritised differently by different researchers. https://doi.org/10.33137/cpoj.v6i2.42176 5 efstathiou k, mcgarry a. 3d printed cosmetic covers for lower limb prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.8. https://doi.org/10.33137/cpoj.v6i2.42176 canadian prosthetics & orthotics journal issn: 2561-987x 3d printed cosmetic covers for lower limb prosthetics efstathiou k, and mcgarry a, 2023 (special issue) future research the criteria and results of the pugh matrix were based on information found through available literature and websites, making the overall approach of this study to be more towards the objective side rather than subjective. a future study could have end-user groups evaluate the existing list of criteria and even expand the list further, on topics such as reimbursement. such study may provide sufficient subjective feedback from the users themselves and offer reliable evidence about the different cosmetic options, thus allowing higher quality evidence-based studies to take place in the future. conclusion although a theoretical novel design was successfully presented through the comparison of the different designs, the data of the study were obtained from the literature and websites of these companies, making the results of the study to be more towards the objective side rather than subjective. researchers are encouraged to conduct more evidence-based studies around cosmetic covers which are oriented more towards the user’s point of view thus allowing future research to be more subjective rather than objective. call to action as we navigate through the intricacies of cosmetic covers, the findings from our study emphasize the need for continued exploration and innovation. now, we call upon researchers, designers, and professionals in the prosthetic industry to seize this opportunity for advancement. our research has identified key areas where novel designs can make a substantial impact. by incorporating the bestperforming criteria from leading companies like unyq,14 limb-art,15 alleles,16 willowwood,17 and aqua-leg,18 we envision a future where prosthetic cosmetic covers not only enhance appearance but also improve functionality and user experience. this study lays the groundwork for a more subjective approach to future research. we encourage the prosthetic community to delve deeper into the lived experiences and preferences of prosthetic users. by combining quantitative data with qualitative insights, we can create cosmetic covers that not only meet technical standards but also resonate with the diverse and unique identities of individuals. acknowledgements none. declaration of conflicting interests dr. anthony mcgarry has no conflict of interest in the preparation of this manuscript. kyriakos efstathiou is co-founder of orthodesigns. authors contribution both authors contributed equally to the research and the writing of this manuscript. sources of support none. references 1.murray cd. being like everybody else: the personal meanings of being a prosthesis user. disabil rehabil. 2009;31(7):573–81. doi:10.1080/09638280802240290 2.highsmith mj, kahle jt, knight m, olk-szost a, boyd m, miro rm. delivery of cosmetic covers to persons with transtibial and transfemoral amputations in an outpatient prosthetic practice. prosthet orthot int. 2016;40(3):343–9. doi:10.1177/ 0309364614564024 3.fukuda s, editor. emotional engineering, vol. 4. springer nature; 2016; doi:10.1007/978-3-319-29433-9 4.cairns n, murray k, corney j, mcfadyen a. satisfaction with cosmesis and priorities for cosmesis design reported by lower limb amputees in the united kingdom. prosthet orthot int. 2014;38(6):467–73. doi:10.1177/0309364613512149 5.ottobock us shop [internet]. [cited 2021 jan 21]. available from: https://www.ottobockus.com/products/custom-silicone-leg-cover/ 6.ottobock.nl. [internet]. [cited 2021 jan 21]. available at: https://www.ottobock.nl/media/catalogus/servicefabrication_customized-solutions_en.pdf 7.ngo td, kashani a, imbalzano g, nguyen ktq, hui d. additive manufacturing (3d printing): a review of materials, methods, applications and challenges. compos b eng. 2018;143:172–96. doi:10.1016/j.compositesb.2018.02.012 8.cai c, tey ws, chen j, zhu w, liu x, liu t, et al. comparative study on 3d printing of polyamide 12 by selective laser sintering and multi jet fusion. j mater process technol. 2021;288:116882. doi:10.1016/j.jmatprotec.2020.116882 9.burge s. the systems engineering tool box [internet]. burgehugheswalsh.co.uk, [cited 2021 jan 27]. available from: https://www.burgehugheswalsh.co.uk/uploaded/1/documents/pug h-matrix-v1.1.pdf 10.kahle jt, highsmith mj. the implications of amputees being overweight [internet]. inmotion;[cited 2021 jan 27]. available from: http://opmarketing.com/storage/research%20encyclopedia/healt h/in%20motion%202008%20amps%20overweight.pdf 11.bk cosmetic foam cover for prosthetic limbs [internet]. [cited 2021 feb 4]. available from: https://wonderfureha.en.made-inchina.com/product/wyymfajvszhg/china-bk-cosmetic-foamcover-for-prosthetic-limbs.html 12.saunders s. limb-art: using hp technology to create stylish 3d printed prosthetic leg covers [internet]. 3dprint.com: the voice of 3d printing/additive manufacturing; 2021; [cited 2021 jan 24]. available from: https://3dprint.com/251688/limb-art-hp-create-3dprinted-prosthetic-leg-covers/ https://doi.org/10.33137/cpoj.v6i2.42176 https://www.ottobockus.com/products/custom-silicone-leg-cover/ https://www.ottobock.nl/media/catalogus/service-fabrication_customized-solutions_en.pdf https://www.ottobock.nl/media/catalogus/service-fabrication_customized-solutions_en.pdf https://www.burgehugheswalsh.co.uk/uploaded/1/documents/pugh-matrix-v1.1.pdf https://www.burgehugheswalsh.co.uk/uploaded/1/documents/pugh-matrix-v1.1.pdf http://opmarketing.com/storage/research%20encyclopedia/health/in%20motion%202008%20amps%20overweight.pdf http://opmarketing.com/storage/research%20encyclopedia/health/in%20motion%202008%20amps%20overweight.pdf https://wonderfureha.en.made-in-china.com/product/wyymfajvszhg/china-bk-cosmetic-foam-cover-for-prosthetic-limbs.html https://wonderfureha.en.made-in-china.com/product/wyymfajvszhg/china-bk-cosmetic-foam-cover-for-prosthetic-limbs.html https://wonderfureha.en.made-in-china.com/product/wyymfajvszhg/china-bk-cosmetic-foam-cover-for-prosthetic-limbs.html https://3dprint.com/251688/limb-art-hp-create-3d-printed-prosthetic-leg-covers/ https://3dprint.com/251688/limb-art-hp-create-3d-printed-prosthetic-leg-covers/ 6 efstathiou k, mcgarry a. 3d printed cosmetic covers for lower limb prosthetics. canadian prosthetics & orthotics journal. 2023; volume 6, issue 2, no.8. https://doi.org/10.33137/cpoj.v6i2.42176 canadian prosthetics & orthotics journal issn: 2561-987x 3d printed cosmetic covers for lower limb prosthetics efstathiou k, and mcgarry a, 2023 (special issue) 13.unyq raises $1m, taking pre-orders for 3d printed below-knee fairings [internet]. www.3ders.org; [cited 2021 jan 25]. available from: https://www.3ders.org/articles/20140628-unyq-raises-takingpre-orders-for-3d-printed-below-knee-fairings.html 14.invent. like no other [internet]. unyq; [cited 2021 jan 22]. available from: https://unyq.com/ 15.alleles, faq [internet]. [cited 2021 jan 25]. available from: https://alleles.ca/faq/ 16.limb-art home page [internet]. [cited 2021 jan 22]. available from: https://limb-art.com/about-limb-art/ 17.transfemoral foam covers [internet]. willowwood. [cited 2021 jan 22]. available from: https://willowwood.com/productsservices/modular-components/cosmetic-foam/transfemoral-foamcovers/ 18.aqualeg home page [internet]. [cited 2021 jan 22]. available from: https://www.aqualeg.com/en authors scientific biography kyriakos efstathiou, born on june 28, 1999, in cyprus, discovered the field of prosthetics and orthotics (p&o) during a chance meeting with the owner of a local p&o clinic. motivated by this encounter, he commenced his studies at the university of strathclyde in 2018, aspiring to become a certified prosthetist and orthotist. during his academic journey, kyriakos encountered the transformative applications of 3d printing in the p&o field. this revelation ignited his mission to make 3d printing more affordable and accessible to clinics. upon completing his studies and work placement, kyriakos returned to cyprus and co-founded orthodesigns alongside savvas savva, a p&o technician. since then, he has been working as a clinician, contributing locally, while managing orthodesigns and steering its expansion both nationally and internationally. dr anthony mcgarry is a senior teaching fellow, health care professionals council registered prosthetist/orthotist, department of biomedical engineering, university of strathclyde. he is responsible for undergraduate /postgraduate tuition in lower limb prosthetics. interests include: clinical management; socket design, shape capture methods and residual limb interface pressures. he obtained a phd in evaluation of prosthetic shape capture systems in the university of strathclyde in 2009. current research focus/publication is in evaluating prosthetic shape capture methods and computer-aided-design. for research activity please visit: https://pureportal.strath.ac.uk/en/persons/anthony-mcgarry https://doi.org/10.33137/cpoj.v6i2.42176 https://www.3ders.org/articles/20140628-unyq-raises-taking-pre-orders-for-3d-printed-below-knee-fairings.html https://www.3ders.org/articles/20140628-unyq-raises-taking-pre-orders-for-3d-printed-below-knee-fairings.html https://unyq.com/ https://alleles.ca/faq/ https://limb-art.com/about-limb-art/ https://willowwood.com/products-services/modular-components/cosmetic-foam/transfemoral-foam-covers/ https://willowwood.com/products-services/modular-components/cosmetic-foam/transfemoral-foam-covers/ https://willowwood.com/products-services/modular-components/cosmetic-foam/transfemoral-foam-covers/ https://www.aqualeg.com/en https://pureportal.strath.ac.uk/en/persons/anthony-mcgarry all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 1 2025 research article pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://doi.org/10.33137/cpoj.v8i1.45142 1 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 research article prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review pousett b.m1,2 *, cumming d1, phillips c3,4, azhari f4, mackay c3,5,6 1. barber prosthetics clinic, vancouver, canada. 2. rehabilitation sciences, faculty of medicine, university of british columbia, vancouver, canada. 3. west park healthcare centre, university health network, toronto, canada. 4. department of mechanical and industrial engineering, university of toronto, toronto, canada. 5. department of physical therapy, temerty faculty of medicine, university of toronto, toronto, canada. 6. school of rehabilitation therapy, queen's health sciences, queen's university, kingston, canada. introduction pregnant women with physical disabilities often face a variety of challenges to receiving high quality perinatal care due to a lack of awareness and education among medical professionals.1,2 limited information is available for both women and health care providers (hcps) about the interaction between disability and pregnancy and about the needs of women living with disability throughout the perinatal period.1-5 this may be detrimental to care, as women have reported benefiting substantially from care where hcps anticipated and carefully managed potential complications or challenges throughout their pregnancy.3 however, to facilitate this level of care, effort is needed to address the gap in hcps’ education about disability and pregnancy, so that they can offer evidence based care.1,5 open access abstract background: little information is available for women with lower limb absence (lla) and their prosthetists regarding expectations for prosthetic treatment during and after pregnancy. a main concern is prosthesis use and what adjustments may be required to sustain mobility. objectives: this study examines the prosthetic treatment of women with lla to understand what specific prosthetic interventions occurred during the perinatal period and to gather information from the prosthetists regarding key learnings to be shared with others. methodology: this study was a retrospective review of clinical records for women with lla who received prosthetic care across canada. between january – may 2023, all 19 women who participated in a previous study on lla and pregnancy consented to have their prosthetist contacted. prosthetists were asked to complete a structured survey documenting appointment details, socket and alignment adjustments made during the perinatal period and key learnings in providing care to this population. findings: 15 prosthetists were contacted to complete surveys for the 19 participants. reviews of clinical records were completed between april – august 2023 by 7 prosthetists covering 18 pregnancies from 11 women with lla (two bilateral transtibial, two unilateral transtibial, four unilateral transfemoral, and three unilateral rotationplasty). socket adjustments were required in 11/18 pregnancies with common methods including circumferential stretching and localized adjustments. alignment adjustments to existing sockets were only required in two pregnancies. additional sockets were required in six pregnancies when the existing socket could no longer be adjusted to achieve comfort, most often during the first six months of pregnancy (the first or second trimester). everyone who had a socket adjustment during pregnancy required additional socket adjustments or new sockets in the postpartum period. prosthetists observed wide variations in physiological changes and prosthetic fit during the perinatal period and shared prosthetic management techniques to address residual limb volume changes. a data collection framework was also proposed to support the ongoing collection of this data to include a wider diversity of women and experiences. conclusion: a wide range of prosthetic treatment interventions may occur during pregnancy and the postpartum period. while prosthetists and women with lla can anticipate that socket and alignment changes may be necessary, sometimes none are required. by preparing for potential fluctuations in prosthetic fit and addressing each individual's needs, prosthetists can help minimize disruptions to mobility throughout pregnancy. article info received: april 8, 2025 accepted: june 9, 2025 published: july 16, 2025 citation pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj. v8i1.45142 keywords lower limb absence; prosthetics; perinatal period; survey; pregnancy; prosthetic treatment; rehabilitation; postpartum period; women; amputation; prosthesis; prosthetist. * corresponding author: brittany mae pousett, cp(c), msc. affiliations: 1) barber prosthetics clinic, vancouver, canada; 2) rehabilitation sciences, faculty of medicine, university of british columbia, vancouver, canada. orcid id: https://orcid.org/0000-0002-2272-7847 e-mail: brittany@pousett.ca; telephone: (604) 321-1115 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 1, article no. 7. 2025 https://doi.org/10.33137/cpoj.v8i1.45142 https://doi.org/10.33137/cpoj.v8i1.45142 https://doi.org/10.33137/cpoj.v8i1.45142 https://orcid.org/0000-0002-2272-7847 mailto:brittany@pousett.ca https://jps.library.utoronto.ca/index.php/cpoj/index 2 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 a notable example of this information gap pertains to pregnant women with lower limb absence (lla), as there is little existing research on their experiences.6,7 pregnant women experience changes to their body composition and center of mass throughout their pregnancy which can have impacts on their balance and mobility.8-10 these changes are typically largest in the second and third trimesters and begin to reverse postpartum, but can fluctuate.9,10 pregnant women with lla experience many of the same physical changes throughout the pregnancy and postpartum period, and reported fluctuations in limb volume and, balance, in addition to increases in pain and fatigue.11,12 however, these changes have particular significance for pregnant women with lla as previous studies found 84% of individuals with lla use prostheses as their primary form of mobility, for an average of 12.5 hours a day.13 as prostheses are fit very intimately to the wearer’s body and are sensitive to volume changes, these changes can negatively impact prosthetic fit, mobility, physical function, balance, and the ability to perform daily tasks.12,14 challenges with prosthesis use can require pregnant women to use other forms of mobility during the perinatal period, such as crutches or wheelchairs.3,11,14 this leaves women with lla with many questions surrounding what to expect in regards to their mobility and prosthesis use when considering having children.12,15 current evidence on prosthetic management during the perinatal period is scarce. a systematic review of pregnancy experience for women with lla included several case series; however, very few commented on prosthesis use or mobility.16 a recent clinical consensus guideline acknowledges that, during pregnancy, female patients with transfemoral amputations may need socket adjustments to accommodate volume gain, trimline modifications to allow for comfortable sitting, and alignment adjustments to account for center of mass changes.15 the guideline also states that new sockets may be necessary but provides no concrete evidence. in one case study, a woman with a transfemoral amputation visited her prosthetist ten times due to physiological changes during a pregnancy,12 while for most people with lla, it is common to visit a prosthetist once every six months unless problems arise.17 this case study found that, during pregnancy, socket comfort, gait speed and functional mobility declined, and that socket adjustments could increase comfort and decrease pain. however, the specific details of the nature of these adjustments were not provided.12 a recent study in canada of mobility outcomes for people with lla during pregnancy reported that among highly active daily prosthesis users, 64% experienced changes in limb size and prosthesis comfort. additionally, 71% of those who used their prosthesis during pregnancy decreased their prosthesis use due to limb swelling and over a quarter reported using a wheelchair or gait aid during pregnancy for mobility.14 while this study14 documents the challenges with limb volume change and prosthesis use, there is no information provided on the specifics of the prosthetic management. the limited evidence has left both health care providers and women with lla without adequate information on prosthetic management during the perinatal period.6,7 therefore, this study seeks to explore the prosthetic treatment of women with lla throughout the perinatal period (defined as the period from the beginning of pregnancy to one year after delivery). we sought to understand which specific prosthetic interventions were used by prosthetists (including socket and/or alignment adjustments, new sockets, etc.) during the perinatal period. we have used the responses to these questions to propose a data collection framework for prosthetists providing care to pregnant women with lla. this framework identifies key areas where evidence is lacking and suggests methods for collecting the necessary data. methodology we conducted a retrospective review of clinical records from prosthetic clinics across canada regarding prosthetic treatment for women with lla during the perinatal period. the review was conducted from april to august 2023. ethics approval was provided by the research ethics board at the university of toronto. participants a previous study examined the physical and psychosocial experiences of women with lla during the perinatal period.7,11 to be eligible for the previous study, women had to live in canada, have a lla, and have been pregnant in the last 10 years. all women who participated in that study were asked if they consented to have their prosthetist contacted to provide a chart review for the dates they were pregnant in the previous 10 years. all 19 women who previously participated consented and provided the name of their prosthetist and the start and end dates (month and year) of each pregnancy. the 15 corresponding canadian prosthetists were invited to participate via email (four of the prosthetists had seen two participants). of the 15 invited prosthetists, 7 completed chart reviews. prosthetists represented clinics in 3 provinces (alberta = 4, british columbia = 2, ontario = 1). they were given the names of the patients who consented and the date range of each pregnancy and asked to extract data from clinical chart to answer questions in a survey format for each pregnancy. see figure 1 for a detailed visual of the recruitment and data collection process. survey the structured survey (appendix a) was developed specifically for this study by authors bmp and fa, one is a prosthetist, and one is a woman with lla who has been pregnant. it was piloted with a prosthetist who had experience providing care to women with lla during https://doi.org/10.33137/cpoj.v8i1.45142 3 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 pregnancy. the survey included a detailed prosthetic prescription for each woman as well as how many appointments they had during their pregnancy and what was done at each appointment (including socket adjustments, alignment adjustments, socket replacements, new componentry required, etc.). the survey also asked if any adjustments occurred in the postpartum period (defined as being one year following pregnancy). prosthetists were given the opportunity to share what they learnt about working with women during the perinatal period and what information they wished was in resource material. figure 1: participant recruitment and data collection process. data analysis quantitative data (such as number of appointments, type of prosthesis, level of amputation, and nature of the adjustment) was analyzed using descriptive statistics. open text boxes were analyzed using conventional content analysis, where we reviewed the data, inductively developed codes from key concepts, grouped the codes together into categories, and summarized the findings for each category.18 these text boxes were also used to provide context to the data captured by quantitative methods. results chart reviews of 18 pregnancies from 11 women with lla were included. this corresponds to 58% of women who consented to have their prosthetists contacted. six women had one pregnancy included, three women had two pregnancies included, and two women had three pregnancies included. levels of amputation included bilateral transtibial amputation/ankle disarticulation (n = 2), unilateral transtibial amputation (n = 2), transfemoral amputation (n = 4), and rotationplasty (n = 3). the average number of appointments during pregnancy was 4.2 (sd: 3.6), with a range of 0 to 12. suspension and interface types can be found in table 1. socket adjustments no socket adjustments were needed in 7/18 pregnancies. two women (a*: bilateral ankle disarticulation with one pregnancy, j: transfemoral amputation with three pregnancies) required no socket adjustments in any pregnancy. two women (k: rotationplasty, g: transtibial amputation) had adjustments made in their first pregnancy but no adjustments made in their second pregnancy. one woman (b: rotationplasty) had no adjustments made in her second pregnancy but the chart review for the first pregnancy was not completed by the prosthetist. socket adjustments were needed or made in the remaining 11/18 pregnancies to adjust sockets as described in table 1. circumferential adjustments were common (n = 5: d, f, g, h & k; 3 transfemoral, 1 transtibial, 1 rotationplasty), especially for those with transfemoral sockets (n = 3: d, f, h), and were done via heating and stretching the socket, removing existing padding or grinding. a transtibial socket (g) was also circumferentially adjusted via heating and stretching and one rotationplasty prosthesis (k) had the corset made larger. localized adjustments were also common (n = 4: c, e, g & h rotationplasty, bilateral transtibial, transtibial, transfemoral), typically via grinding to remove material. areas frequently adjusted were fibular head (transtibial), medial hamstring (transtibial), anterior distal tibial (transtibial), anterior proximal tibia (transtibial), knee condyles (transtibial), dorsum of foot (rotationplasty) and medial wall (transfemoral). for one woman using a transfemoral waist belt for suspension, the strap was made longer. in regard to when adjustments were done, localized adjustments tended to be early in pregnancy, during the first or second trimester, while circumferential adjustments were spread out across all trimesters. alignment adjustments alignment adjustments on existing sockets were only done in 2/18 pregnancies – once to lengthen the prosthesis (d: transfemoral – 3rd trimester) and once to shift the socket medially to widen the base of support (l: transtibial – 3rd trimester). the prosthesis that was lengthened was shortened again in the postpartum period. one clinician measured the changing center of mass of their patient with a transfemoral amputation (j) using the lasar posture (ottobock) and found it moved 29 mm forward from baseline to 37 weeks pregnant. at home management at home management was rarely documented. socks and shrinkers were each provided to one patient (a, b). one * letters refer to subject identifiers listed in table 1. january – may 2023 19 women with lower limb absence completed an interview. all 19 women consented to have their prosthetist contacted to complete a survey. april – august 2023 15 prosthetists were invited to complete a survey reviewing the clinical records for the women during and after their pregnancies. august 2023 7 of the 15 prosthetists completed chart reviews. this included data from 11 women with a total of 18 pregnancies. 4 prosthetists were the primary clinician for multiple participants. https://doi.org/10.33137/cpoj.v8i1.45142 4 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 woman (a) was fit with diagnostic transtibial/ankle disarticulation sockets that were too large right after she found she was pregnant, in anticipation of limb volume gain. the prosthetist reported that this worked well and was able to support socket fit management by providing thinner socks as the pregnancy progressed. new sockets twelve pregnancies did not require a new socket, and six pregnancies did require a new socket (d x 2, e, f, g, l) (table 1). new sockets were required when existing sockets could no longer be adjusted to comfortably fit. in one situation, a new socket was required but not made due to the inability to receive funding approval. when new sockets were fit, dynamic alignment was done as is standard clinical practice. new sockets were most often made in the first or second trimester. one prosthetist commented that a new socket was needed but the patient opted to persevere with their existing socket (l). postpartum period after pregnancy, nothing was done in the 7/18 pregnancies who had no adjustments made during pregnancy. two women (c, g) required a new socket post-delivery as their current socket no longer fit appropriately: one who had adjustments made during pregnancy (c: rotationplasty), and the other who had both adjustments and 2 new sockets made during pregnancy (g: transtibial). one woman (d: transfemoral) required adjustment to her alignment after her first and second pregnancies and as after pregnancy she switched from a larger socket that was fit during pregnancy, to a previously worn socket that was smaller. three women (e, h, k) required socket adjustments to reverse adjustments made during pregnancy. all women who had adjustments during pregnancy also had adjustments after pregnancy. learnings & take aways prosthetists reported key learnings from providing prosthetic care to women with lla during the perinatal period. in the prenatal period, prosthetists reported observing a wide range of physiological changes and changes to prosthetic fit. some found that their patients managed without any changes to their prostheses but that it depended on the individual and level of amputation. table 1: summary of prosthetic treatment for each woman included in the chart review. id lla level interface / suspension system pregnancies (n) appts (n)* during pregnancy during postpartum notes socket adjustments (trimester) alignment adjustments (trimester) new socket (trimester) adjustment made after pregnancy a btt socks / anatomical/supra condylar 1 of 1 3 none none no none fit diagnostic socket with 4 ply socks in t1 (before pregnancy known). socks were supplied. b rp socks / anatomical/ supra-condylar 1 of 2 (only 2nd included) 2 none none no none provided shrinker socks to use if needed. patient asked prosthetist for peer support connections after finding no resources. c rp socks / cuff/strap 1 of 1 1 1 localized adjustment: removed padding on dorsum of foot (t3) none no new socket required as limb was smaller than before pregnancy d tf silicone liner / locking liner pin 2 of unknown 5 3 circumferential adjustments: stretched socket globally over cast. (once in t2 on first socket, twice in t3 on new socket) none yes (t2) alignment – did not specify how 8 2 circumferential adjustments: stretched socket from first pregnancy globally over cast (t1, t2) lengthened prosthesis (t3) yes 2 sockets (both t2) shortened prosthesis. refit previous socket switched to socket from first pregnancy early in t1 before any adjustments done e btt gel liner / suction sleeve 1 of 1 10 4 localized adjustments: adjusted fibular head via heating (t1), adjusted medial hamstring and anterior distal tibia by heating and grinding (t1), adjuster posterior trimline via grinding (t2), adjusted proximal anterior tibia via grinding & medial hamstring via heating (t2) none yes (t1) pressure relief – did not specify where or how. * number of appointment. https://doi.org/10.33137/cpoj.v8i1.45142 5 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 others reported the difficulty of managing prosthesis use during pregnancy due to changes with weight, limb volume, socket pressure, and the location of the center of mass. a wide range of specific learnings were reported with prosthetists reporting different observations about the patient they worked with. these included that “volume changes are greatest in the 3rd trimester”, “adjustments are needed more often for individuals with transfemoral amputations than transtibial amputations”, “patients with congenital limb loss have less volume concerns and need for adjustments” and “weight gain impacts the thigh not the foot for people with rotationplasty amputations”. however, these observations are not necessarily supported by the aggregated data. for example, we did not see the most adjustments or new sockets in the third trimester to match the observation that this is when there were the greatest volume changes. also, for people with rotationplasty amputations, we saw examples of both the foot and the table 1 (continued): summary of prosthetic treatment for each woman included in the chart review. id lla level interface / suspension system pregnancies (n) appts (n)* during pregnancy during postpartum notes socket adjustments (trimester) alignment adjustments (trimester) new socket (trimester) adjustment made after pregnancy f tf silicone liner / seal-in liner 1 of 1 3 1 circumferential adjustment: stretched proximal 2/3 of socket(t1) none yes (t1). refit a previous check socket. unknown. did not follow up with that clinic. g tt gel liner / locking liner – pin 2 of 3 (2nd & 3rd included) 9 2 localized adjustments: adjusted knee condyles via grinding (t1, t1). 1 circumferential adjustment– stretched 2nd new socket distally (t3). none yes (2 sockets) (t1 & t2) new socket new sockets made after localized adjustments. 3 none none no none h tf skin / skin fit suction 3 of 3 12 5 localized adjustments: adjusted medial trimline by grinding (t1), adjusted medial trimline by grinding and heating (t1), added padding to lateral socket (t2), added padding to anterior socket (t2), removed padding from lateral socket (t3) none no added padding to all 4 walls of socket. new socket was fit before pregnancy was known, adjustments may have been part of routine fitting. 6 1 localized adjustment: removed padding from medial, lateral and anterior socket (t2) none no replaced padding that was removed during pregnancy prosthetist would have liked to increase socket volume in last month of pregnancy but didn’t want to make changes that could not be easily reversed. 7 1 localized adjustment: adjusted distal lateral femur by grinding (t1). 1 circumferential adjustment– ground proximal socket as much as possible before risking socket failure. (t2) none no added additional padding as volume decreased. j tf socks / anatomical/ supracondylar & cuff/strap 3 of 3 2 none none no none lengthened waist belt (t2) 1 none none no none 1 none none no none k rp neoprene sock / cuff/strap 2 of 2 1 1 circumferential adjustment: lengthened thigh corset (t2) none no shortened thigh corset 0 none none no none l tt gel liner / locking liner pin 1 of 1 2 needed (not made due to funding) shift socket medially to widen base of support (t3) yes(t3) (not made due to funding) none patient opted to persevere with poorly fitting socket level of amputation: btt = bilateral transtibial or ankle disarticulation, rp = rotationplasty, tf = transfemoral, tt = transtibial. trimester: t1 = first trimester, t2 = second trimester, t3 = third trimester. localized: adjustment done in a specific area. circumferential: adjustment done over entire circumference of the socket. * number of appointment. https://doi.org/10.33137/cpoj.v8i1.45142 6 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 thigh section needed to be adjusted. one prosthetist reported that “setting up a schedule to meet regularly [over the pregnancy] was a good way to keep small problems small”. in the postpartum period, prosthetists reported a wide range of learnings; some found that volume changes reversed quickly, while some found it took approximately three months to get back to a pre-pregnancy socket fit. managing volume change prosthetists reported their key learnings surrounding finding success with several different volume management techniques, including: • using interfaces that can be easily modified to allow maximum adjustment (e.g., flexible inner liners, pe-lite liners) • heating and stretching sockets • holding on to previous sockets so that one has multiple sockets of different sizes to help accommodate volume changes during and after pregnancy five prosthetists commented that making “future-proof” sockets that allow for volume adjustment is helpful. ways of doing this include making sockets larger, making sockets with liners that can be removed, making sockets with padding that can be removed, etc. helpful resources one prosthetist reiterated that there are no resources available for pregnant women with lla but that peer support and advice from other women with lla who have been pregnant can be helpful. the remaining prosthetists did not comment on any helpful resources. discussion this study presents the experiences of prosthetists providing care to women with lla during and after pregnancy, and the wide range of prosthetic treatment interventions that occur. the review of clinical records includes women with a wide range of levels of amputations, including both ankle disarticulation and rotationplasty amputations, which are infrequently included in research. some women did not require any prosthetic appointments or adjustments during pregnancy, while others visited their prosthetist frequently. these findings spanned all levels of amputation, and no level-specific recommendations can be made due to the small number of participants and the wide range of experiences. however, for those who did not require any adjustments over their pregnancy, many, though not all, of these were women in their second or third pregnancies and had sockets that had previously been adjusted. prosthetists should be diligent—particularly in first pregnancies—to anticipate and address any prosthesis issues that arise, while also being aware that women may require no adjustments in pregnancy. as always, it is important to treat each patient and their unique situation individually. prosthetists demonstrated a large toolkit of possible prosthetic treatment interventions when working with women whose pregnancy-related changes did require such interventions. these most often included global socket adjustments, localized socket adjustments, and new sockets. while limb volume change is reported to peak later in pregnancy,9,10 adjustments did not follow the same trend. localized adjustments tended to be made earlier in pregnancy (in the first and second trimesters) and circumferential adjustments were made approximately evenly throughout all trimesters. all women who required a socket adjustment during pregnancy had adjustments after pregnancy as well, demonstrating that it is important to reassess prosthetic fit and function in the year after pregnancy. while not frequently documented within the clinical charts, one prosthetist reported in the open-ended questions that they provided supplies for at-home management. in the previous phase of this research, women with lla frequently discussed how their prosthetists provided them with education and supplies for at-home management that helped them throughout their pregnancies.11 this discrepancy highlights the importance of the at-home management strategies for women with lla and emphasizes that prosthetists need to ensure they provide education on appropriate at-home management strategies in the future. we know that the center of mass changes throughout pregnancy, which may impact prosthesis function.12,15 alignment is sensitive to the location of the center of mass; however, no one in our study reported making an alignment adjustment in the anterior-posterior plane, and only one prosthetist reported making an adjustment in the mediallateral plane. it is unclear if this is because the center of mass moves so slowly that the body makes other adaptations and therefore prosthesis function is not impacted in a way requiring alignment or componentry adjustments. this is something that needs to be more closely noted in the future. new sockets were required for those with residual limb volume and shape changes beyond what could be accommodated for in an existing socket. in this study, most of the sockets required were made in the first or second trimester, even though the weight gain and limb volume change tend to be the largest later in pregnancy, in the second and third trimester. while our data cannot explain this discrepancy, it appears the prosthetists included in this chart review were proactive about keeping sockets fitting comfortably early on in pregnancy and mentioned several strategies that allowed them to accommodate for volume https://doi.org/10.33137/cpoj.v8i1.45142 7 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 increases over pregnancy. our previous research has found barriers to accessing prosthetic care, including scheduling constraints, funding availability and the time it takes for a socket to be made may limit women from accessing prosthetic care.11 women who need adjustments later in pregnancy but choose not to seek prosthetic care were not captured in this chart review study, except for the one woman whose prosthetist noted that a socket was required but not supplied (l) and one prosthetist who commented that they would have liked to further increase the socket volume in the last month of pregnancy but didn’t want to make a non-reversable change (h). future research should look specifically into when new sockets are required in pregnancy, regardless of if treatment is sought. overall, prosthetists demonstrated strategies similar to those mentioned by women with lla, notably that planning ahead is key to successfully managing prosthesis fit throughout pregnancy.7 these planning-ahead techniques included having conversations early, making adjustable interfaces, using thermoplastic check sockets that can more easily be stretched or adjusted, keeping old sockets for women of childbearing age in case they are needed, making sockets too big early in pregnancy, and using techniques to future-proof sockets. data collection framework the information gathered in this study sets the foundation for a larger data collection framework (appendix b). while the current study provides more information than previous studies on experiences of pregnant women with lla regarding their prosthetic treatment,12,14,16 additional data is needed to provide a comprehensive overview, which would include the diversity of women and their specific prostheses. the framework should include details on socket adjustments, new sockets, alignment adjustments and athome management. when documenting new sockets specifically, it should be noted when the new socket is identified as being needed, regardless of if it is supplied. women and prosthetists may choose to tolerate a poorly fitting socket or switch to using other forms of mobility instead of investing the time and money required to make a new socket. overall, the format of the current survey seemed to have been satisfactory for the purposes of this study and the data was effective for describing their experience and informing future care. 47% of the 15 prosthetists who were invited to participate completed the survey. it is important to note that of 15 invited prosthetists, it was discovered that one prosthetist had passed away and two prosthetists had retired from their clinical practice. from the current review, data on socket adjustments and the provision of new sockets seemed straightforward to collect, while information on alignment and at-home management was less specific. in the future, attention should also be given to documenting alignment adjustments and to education on at-home management techniques. we may also need to explore different ways of asking these questions. data collection needs to continue to include information on patient demographics (e.g., cause of amputation, level of amputation, bmi, ethnicity, activity level, etc.) and pregnancy details (e.g., number of pregnancies, time in the pregnancy that adjustment is made, weight gain, etc.). in the current study, prosthetists hypothesized that the third trimester was the trimester most likely to require adjustments to accommodate for changes, and that women with congenital lla have less limb volume and shape change issues; however, we do not have enough data to provide evidence for or against these speculations. in addition, it could be helpful to collect more details regarding the postpartum period, including details on how the socket fits in the 3–12 months after birth. in the current study, prosthetists commented that it takes approximately three months to get back to pre-pregnancy limb volume, despite women commenting it took up to 18 months,11 demonstrating the discrepancies between these two points of view. the proposed framework builds off of the existing chart-review survey and adds components which should be reported by both the patient and the prosthetist. information from prosthetists should rely on objective adjustment data, while women with lla can provide any additional contextual information. in the future, this data collection framework could be expanded to collect information on the experiential aspects of pregnancy from women with lla as well. while this study provides suggestions for the questions and format of a data collection framework, it does not identify a sustainable location. perhaps this research could inform limb loss registries, which could expand to have a section dedicated to pregnancy and limb loss.19 limitations while this study fills a gap regarding information for prosthetists caring for pregnant women, it was done in a canadian context with a small subset of prosthetists. given the variety of experiences of women with lla during the perinatal period, a larger dataset is needed over a wider geographic area with more diversity of women and their prosthetic prescriptions. in addition, there may be other factors that influence prosthetic treatment such how well the socket was fitting prior to pregnancy or how often a particular patient typically requires adjustments to maintain a comfortable socket fit. we cannot make any claims regarding the correlation between level of amputation and prosthetic treatment due to the lack of other demographic factors (e.g. age, prosthetic componentry, activity level, prosthetic use, etc.). these demographic factors were not included in the scope of the current study but are included in the data collection framework so that future studies can make more robust conclusions and recommendations. https://doi.org/10.33137/cpoj.v8i1.45142 8 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 in addition, this study was a survey of clinical records with a few additional questions added to gather the ideas of the prosthetists. the time between seeing the patient and completing the review could have been up to 10 years, which may impact recall if prosthetists tried to supplement data written in the chart. in the future, it would be ideal to complete the review in the 12-18 months after pregnancy. conclusion this study provides valuable information regarding the prosthetic treatment of women with lla during the perinatal period. it highlights the diverse experiences of prosthetists providing care to these women and the wide range of prosthetic interventions that were found appropriate. it also provides suggestions for future data collection to gather additional information to address this critical gap in knowledge. given the findings from this study, we can begin to better educate women with lla and their prosthetists regarding what to expect during and after pregnancy and the range of experiences they may encounter. this can also provide information to prosthetists to ensure they have the tools and knowledge to provide their patients with as smooth a journey as possible. by providing information on the range of experiences and prosthetic management techniques, we can give women with lla and their prosthetists the information they need plan ahead for a variety of scenarios, leading to decreased anxiety about uncertainty regarding how to manage limb volume change and prosthesis fit during the perinatal period. acknowledgements funding was provided through a grant from the war amps. we would like to thank the prosthetists who took the time to complete the chart review and the women who consented to letting us contact their prosthetists. declaration of conflicting interests the authors have no conflicts of interest. authors’ contribution • brittany mae pousett: conceptualization, funding acquisition, project administration, study design, data analysis, manuscript writing. • donna cumming: project administration, study design, manuscript editing. • clara phillips: conceptualization, data analysis, manuscript editing. • fae azhari: conceptualization, study design, manuscript editing. • crystal mackay: conceptualization, study design, manuscript editing, supervision. sources of support funding was provided through a grant from the war amps. references 1.tarasoff la. experiences of women with physical disabilities during the perinatal period: a review of the literature and recommendations to improve care. health care women int. 2015;36(1):88-107. doi:10.1080/07399332.2013.815756 2.mitra m, long-bellil lm, iezzoni li, smeltzer sc, smith ld. pregnancy among women with physical disabilities: unmet needs and recommendations on navigating pregnancy. disabil health j. 2016;9(3):457–63. doi:10.1016/j.dhjo.2015.12.007 3.long-bellil l, mitra m, iezzoni li, smeltzer sc, smith l. the impact of physical disability on pregnancy and childbirth. j womens health. 2017;26(8):878-885. doi:10.1089/jwh.2016.6157 4.tarasoff la. “we don’t know. we’ve never had anybody like you before”: barriers to perinatal care for women with physical disabilities. disabil health j. 2017;10(3):426-433. doi: 10.1016/j.dhjo.2017.03.017 5.smeltzer sc, mitra m, iezzoni li, long-bellil l, smith ld. perinatal experiences of women with physical disabilities and their recommendations for clinicians. jognn. 2016;45(6):781-789. doi: 10.1016/j.jogn.2016.07.007 6.hanna e, donetto s. the pregnancy experiences of amputee women: a qualitative exploration of online posts. j reprod infant psychol. 2021;43(3):1–11. doi: 10.1080/02646838.2021.2004301 7.cumming d, mackay c, phillips c, azhari f, pousett bm. resources, relationships, and resilience: the psychosocial experiences of women with lower limb absence during pregnancy and postpartum. disabil health j. 2024;17(3):1–6. doi : 10.1016/j.dhjo.2024.101621 8.takahashi y, kaji t, yasui t, yoshida a, yonetani n, suzue n, et al. ultrasonographic changes in quadriceps femoris thickness in women with normal pregnancy and women on bed rest for threatened preterm labor. sci rep. 2022;12(1). doi: 10.1038/s41598-022-22467-8 9.haddox ag, hausselle j, azoug a. changes in segmental mass and inertia during pregnancy: a musculoskeletal model of the pregnant woman. gait posture. 2020;76:389–95. doi: 10.1016/j.gaitpost.2019.12.024 10.widen em, gallagher d. body composition changes in pregnancy: measurement, predictors and outcomes. eur j clin nutr. 2014;68(6):643-52. doi: 10.1038/ejcn.2014.40 11.pousett bm, cumming d, azhari f, phillips c, mackay c. the physical experiences of women with lower limb absence during pregnancy and postpartum: symptoms, prosthesis management & mobility. disabil rehabil. 2025;47(6):1587-1594. doi: 10.1080/09638288.2024.2378234 12.kahle jt, miro rm, ho lt, gagliardotto a, swanson ae. effect of pregnancy on anthropometrics, comfort, and functional performance for women living with transfemoral limb loss: case report. prosthet orthot int. 2023;48(3):315-319. doi: 10.1097/pxr.0000000000000260 13.raichle ka, hanley ma, molton i, kadel nj, campbell k, phelps e, et al. prosthesis use in persons with lower-and upper-limb amputation. j rehabil res dev. 2008;45(7):961–72. doi: 10.1682/jrrd.2007.09.0151 https://doi.org/10.33137/cpoj.v8i1.45142 9 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 14.bateman ea, viana r, sales d, payne mwc. pregnancy after amputation: a national survey of prosthetic and mobility outcomes in women with lived experience. prosthet orthot int. 2024;49(2):179-184. doi: 10.1097/pxr.0000000000000407 15.o’brien e, stevens pm, miro r, highsmith mj. transfemoral interface considerations: a clinical consensus practice guideline. prosthet orthot int. 2023;47(1):54-59. doi: 10.1097/pxr.0000000000000182 16.bateman ea, frengopoulos c, viana r, payne mwc. pregnancy after amputation: a systematic review of pregnancy experiences for women with lower extremity amputations. am j phys med rehabil. 2022;101(11):1066–75. doi: 10.1097/phm.0000000000001949 17.hanger clinic. patient care manual: above-knee amputation [internet]. austin (tx): hanger clinic; [cited 2024 june 13]. available from: https://hangerclinic.com/wpcontent/uploads/patient-care-manual-above-knee.pdf 18.hsieh hf, shannon se. three approaches to qualitative content analysis. qual health res. 2005;15(9):1277–88. doi: 10.1177/1049732305276687 19.limb loss and preservation registry [internet]. mclean, va: limb loss and preservation registry. [cited 2024 june 13]. available from: https://www.llpr.org/ https://doi.org/10.33137/cpoj.v8i1.45142 https://hangerclinic.com/wp-content/uploads/patient-care-manual-above-knee.pdf https://hangerclinic.com/wp-content/uploads/patient-care-manual-above-knee.pdf https://www.llpr.org/ 10 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 appendix appendix a a p p e n d ix a https://doi.org/10.33137/cpoj.v8i1.45142 11 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 a p p e n d ix a https://doi.org/10.33137/cpoj.v8i1.45142 12 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 a p p e n d ix a https://doi.org/10.33137/cpoj.v8i1.45142 13 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 a p p e n d ix a https://doi.org/10.33137/cpoj.v8i1.45142 14 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 a p p e n d ix a https://doi.org/10.33137/cpoj.v8i1.45142 15 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 a p p e n d ix a https://doi.org/10.33137/cpoj.v8i1.45142 16 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 a p p e n d ix a https://doi.org/10.33137/cpoj.v8i1.45142 17 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 appendix b section 1a: patient details: general to be completed by the prosthetist or patient, depending on if this information is documented in the clinical records. birth month and year: race or racial background: (check all that apply) • black (african, african canadian, afro-caribbean descent) • east asian (chinese, japanese, korean, taiwanese descent) • indigenous (first nations, inuk/inuit, métis descent) • latin american (hispanic or latin american descent) • middle eastern (e.g., afghan, egyptian, iranian, kurdish, lebanese, turkish) • south asian (e.g., bangladeshi, indian, indo-caribbean, pakistani, sri lankan) • southeast asian (cambodian, filipino, indonesian, thai, vietnamese, or other southeast asian descent) • white (european descent) • other • do not know • prefer not to answer side of amputation: (check all that apply) • right • left for each side with an amputation: level of amputation: • symes / ankle disarticulation • transtibial • knee disarticulation • transfemoral • hip disarticulation • rotationplasty • hemipelvectomy • other: cause of amputation: • vascular/diabetes • trauma • infection • cancer • congenital • other: ________ section 1b: patient details at time of pregnancy to be completed by the prosthetist: for each side with an amputation, what was the prosthetic prescription at the time of pregnancy? prosthetic interface: • none (skin) • socks • pelite/foam liner • gel liner • silicone liner • urethane liner • neoprene sock • other: ________ a p p e n d ix b https://doi.org/10.33137/cpoj.v8i1.45142 18 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 suspension mechanism: • skin fit suction • anatomical/supracondylar • cuff/strap • tension sleeve • suction sleeve • locking liner – pin • locking liner lanyard • seal-in liner • elevated vacuum • other: ___________ socket design: • window (obturator) • total surface bearing (transtibial) • patella tendon bearing (transtibial) • specific weight bearing (transtibial) • hydrostatic (transtibial) • thigh lacer • quadrilateral (transfemoral) • narrow ml (transfemoral) • ischial containment (transfemoral) • sub-ischial (transfemoral) • maas (transfemoral) • other:____________ foot: knee or side joints: (if applicable): hip joint (if applicable): to be completed by the patient: what was your activity level at the time of pregnancy? • low • moderate • high • extremely high did you wear your prosthesis as your primary means of mobility for your entire pregnancy? • yes • no if no, when did you stop using it and what form of mobility did you use instead? what was your pre-pregnancy weight? section 2: pregnancy details to be completed by the patient: how many times have you been pregnant? what was the anticipated due date? (this will be used to calculate in which trimester adjustments were done.) what was the baby’s birth date? (this question in combination with the question above can calculate the dates of pregnancy). how much weight did you gain during each pregnancy? survey section 3: appointments to be completed by the prosthetist: how many appointments did this patient have during their pregnancy? (calculated as the 9 months before the due date to the birth date). a p p e n d ix b https://doi.org/10.33137/cpoj.v8i1.45142 19 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 for each appointment: what was the date of the appointment? what was the goal of this appointment? were any socket adjustments made? (if yes, answer the questions below) a. what was the goal of the socket adjustment? b. was pressure added or removed? c. what was the method of adjustment • padding • heating • grinding • other: ________ d. which location(s) was the adjustment made in? • anterior distal tibia • medial tibial flare • posterior tibial area • fibula • knee condyles • medial thigh • lateral thigh • anterior thigh (scarpas) • posterior thigh • other: _______ e. please describe the adjustment in as much detail as possible: were any alignment adjustments made? (if yes, answer the questions below) a. what was the goal of the alignment adjustment? b. which of the following was done? • socket flexion • socket extension • socket abduction • socket adduction • socket medial shift • socket lateral shift • socket posterior shift • socket anterior shift • knee internally rotated • knee externally rotated • foot inverted • foot everted • foot toed in • foot toed out • prosthesis lengthened • prosthesis shortened • other: _________ c. please describe the alignment adjustment in as much detail as possible: was a new socket indicated? (if yes, answer the questions below) a. please describe why it was determined that a new socket was required. b. will the new socket be made? if no, please describe why it will not be made (i.e., funding, time requirements, etc.) c. if the socket is not fitting properly, will the patient use alternative means of mobility? if so, what mobility devices will they use? were any consumables or components required at this appointment relevant to the pregnancy? (if yes, answer the questions below) a. pease describe the consumables and components required at this appointment relevant to the pregnancy. was any education provided on at-home management strategies (e.g., wearing shrinker socks when not wearing the prosthesis, switching to thinner socks or liners, etc.)? if so, please describe. section 3: post-natal questions to be completed by the prosthetist: a p p e n d ix b https://doi.org/10.33137/cpoj.v8i1.45142 20 pousett b.m, cumming d, phillips c, azhari f, mackay c. prosthetic treatment of women with lower limb absence during pregnancy & the postpartum period: a chart review. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 7. https://doi.org/10.33137/cpoj.v8i1.45142 canadian prosthetics & orthotics journal issn: 2561-987x pregnancy and postpartum prosthetic care in women with lower limb absence pousett et al., 2025 please describe all the adjustments made in the year after pregnancy that revered adjustments made during the pregnancy, accommodated volume changes or involved the provision of a new socket. section 4: general questions to be completed by the prosthetist: did you (the prosthetist) learn anything while treating this patient during pregnancy that you think may be helpful for other people treating pregnant individuals with lower extremity prostheses to know? if yes, please describe. is there anything else from treating this patient during this pregnancy that you would like to share with us? a p p e n d ix b https://doi.org/10.33137/cpoj.v8i1.45142 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 2 2025 technical/clinical note withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i2.46063 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 technical/clinical note withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees withey a1*, cazzola d1, tabor a2, seminati e1 1. department for health, university of bath, bath, uk. 2. faculty of health and applied sciences, university of the west of england, uk. introduction correct placement of anatomical markers in threedimensional (3d) gait analysis is crucial for ensuring valid biomechanical outcomes. however, withinand betweensessions variability in markers placement can introduce errors in kinematic movement analysis, especially in longitudinal studies where participants are monitored repetitive times across different sessions, such as in the monitoring of patients’ rehabilitation.1 research has shown that human error in inconsistent markers placement can affect kinematic gait data in terms of average joint angles by up to 75%.1 together with marker placement, a correct static trial is a fundamental step in motion analysis, as it establishes segment lengths at the start of a measurement, which are essential for many kinematic and kinetic gait calculations.2,3 it also provides a reference for the participant’s anthropometrics and anatomical alignment, which helps define body segment coordinate systems with respect to the ground, and it allows comparison of data across participants or trials by providing a standardized reference. therefore, exploring the reliability of withinand between-session anatomical marker placement and static posture with respect to kinematic outcomes is an important area of study when designing longitudinal studies. while marker placement reliability has been welldocumented in the general population with skin marker placement variability (standard deviation) within 10 mm and 12 mm for intra-evaluator and interevaluator, respectively,4 limited research has examined its consistency in individuals with lower-limb amputation (lla). this population presents unique challenges due to altered anatomy, soft tissue distribution, prosthetic limb interfaces and suspensions (especially for above knee amputations), and limb differences, all of which may influence marker placement precision and subsequent biomechanical interpretations. moreover, a substantial proportion of individuals with lla are overweight or obese, with prevalence rates ranging from 28% to 48%.5,6 excess subcutaneous fat can obscure * corresponding author: alexandra withey, affiliation: department for health, university of bath, bath, uk. e-mail: anmw20@bath.ac.uk orcid id: https://orcid.org/0000-0001-9422-2306 open access abstract background: accurate placement of anatomical markers is essential for valid three-dimensional (3d) gait analysis, yet individuals with lower-limb amputation (lla) pose unique challenges due to altered anatomy, prosthetic interfaces, and increased adiposity. objective: this study assessed withinand between-session reliability of pelvis marker placement and static posture kinematics in adults with unilateral lla. methodology: fourteen adults with unilateral lla (age: 58 ± 15 years, height: 174.6 ± 7.5 cm, body mass: 91.1 ± 27.7 kg, bmi: 29.6 ± 7.5 kg/m²; eleven transtibial, three transfemoral) participated in two sessions spaced 3–13 months apart. reliability of marker distances and static posture kinematics were assessed using intraclass correlation coefficients (icc) and standard error of measurement (sem). findings: within-session reliability of pelvis marker distances was good to excellent (icc ≥ 0.78), whereas between-session reliability was lower (icc as low as 0.14), particularly for posterior superior iliac spine markers. pelvis kinematics demonstrated moderate reliability within sessions (average icc ≈ 0.71), but trunk kinematics showed poor reliability. sem values were low (<5°), suggesting acceptable absolute consistency despite variable iccs, likely driven by postural changes and prosthetic factors. conclusion: findings support reliable pelvis marker placement within sessions but highlight challenges for longitudinal consistency. multiple trial collections and standardised posture protocols are recommended to improve long-term reliability. article info received: september 22, 2025 accepted: october 12, 2025 published: october 20, 2025 citation withey a, cazzola d, tabor a, seminati e. withinand betweensession reliability of pelvic marker placement and posture in lowerlimb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i 2.46063 keywords lower-limb amputation; gait analysis; posture; kinematics; longitudinal consistency; marker placement reliability. journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 2, article no. 2. 2025 https://doi.org/10.33137/cpoj.v8i2.46063 mailto:anmw20@bath.ac.uk https://orcid.org/0000-0001-9422-2306 https://doi.org/10.33137/cpoj.v8i2.46063 https://doi.org/10.33137/cpoj.v8i2.46063 https://jps.library.utoronto.ca/index.php/cpoj/index 2 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 anatomical landmarks, causing inconsistent marker placement and errors in joint kinematics.7,8 despite these known challenges, the reliability of pelvis marker placement among individuals with lla remains largely unexplored, particularly in those with higher bmi. this study focused primarily on evaluating the test-retest reliability of pelvis marker placements withinand betweensessions in individuals with lla, together with static trial posture variability for the pelvis and trunk segments. we expected pelvis marker placement to demonstrate reliability, with icc values exceeding 0.70 across a diverse sample of participants with lla and varying body mass index (bmis). an intraclass correlation coefficient (icc) value of 0.70 or higher is acceptable for internal consistency and reliability in this population.9-11 methodology thirteen males and one female with unilateral lla (age: 58 ± 15 years; height: 174.6 ± 7.5 cm; weight: 91.1 ± 27.7 kg; bmi: 29.6 ± 7.5 kg/m2) were recruited; eleven transtibial and three transfemoral (table 1). participants were classified per national health service (nhs) body mass index (bmi) guidelines: seven as obese (bmi ≥ 30), two as overweight (bmi 25-29.9), and five as healthy weight (bmi < 25). ethical approval was obtained (rec 23/ee/0090). participants were recruited from the nhs bristol centre for enablement and the portsmouth enablement centre. recruitment commenced in july 2023 and continued for 12months. clinicians who were part of the participants’ routine care team identified eligible patients during assessment days according to the inclusion and exclusion criteria. inclusion and exclusion criteria participants were included if they were over 18 years of age, had a unilateral lower-limb amputation (above or below the knee), were newly fitted with a prosthesis (three months post-amputation) and were able to walk on level ground. exclusion criteria were balance disorders, congenital lowerlimb absence, inability to provide consent for prosthetic use and individuals at serious risk of complications to the sound limb that could limit normal rehabilitation. these clinicians made the initial approach to potential participants and introduced the study. the primary investigator of this study (aw) then provided information sheets and informed consent forms to eligible participants. experimental set-up a motion capture system (qualisys, sweden) with eight infrared cameras was used to detect retroreflective markers. the system was calibrated prior to data collection using a qualisys calibration wand and l-frame, achieving a residual error of < 1 mm (0.70 ± 0.10 mm). cameras recorded at a sampling rate of 200 hz, and the global coordinate system was aligned with a fixed floor platform (600 x 400 x 35 mm). for each static trial described in session 1 and 2, the participants were asked to stand for 10 seconds in the same anatomical reference position relative to the platform. protocol participants completed two motion capture sessions (≈ 45 minutes each). in both sessions, a single evaluator with three years of experience in collecting 3d motion capture data and running sessions on individuals with lla, applied nine pearl retroreflective markers (diameter: 15.9 mm) to the table 1: individual participants’ characteristics at session 1 and session 2. mean values ± standard deviation (sd) are reported at the end of the table. participant limbloss level cause of limb loss sex height (cm) age (years) mass (kg) time since limb loss (weeks) session 1 session 2 session 1 session 2 session 1 session 2 p01 tt traumatic m 168 39 40 87 73 18.7 70.8 p02 tt vascular m 168 84 85 59 62 16.1 58.1 p03 tf sepsis m 160 70 70 59 62 19.4 32.0 p04 tt vascular m 173 75 76 91 90 34.7 87.6 p05 tt vascular m 179 48 49 111 106 27.3 53.3 p06 tt vascular m 185 43 44 97 105 14.1 66.8 p07 tf vascular m 179 53 54 68 78 11.4 50.3 p08 tt cancer m 178 46 47 110 94 14.1 52.7 p09 tt chronic pain m 173 42 42 108 107 19.9 59.8 p10 tt vascular m 183 46 46 162 134 31.4 43.8 p11 tt vascular m 185 69 69 105 101 19.3 59.2 p12 tt vascular m 175 72 73 69 74 18.0 70.1 p13 tt vascular m 173 67 68 69 73 13.4 59.4 p14 tf vascular f 165 54 55 80 83 15.1 67.0 average 175 ± 8 58 ± 15 58 ± 15 91 ± 28 89 ± 20 19 ± 7 59 ± 13 https://doi.org/10.33137/cpoj.v8i2.46063 https://www.nhsinform.scot/healthy-living/weight-loss/understanding-healthy-weight/how-do-i-measure-my-body-mass-index-bmi https://www.nhsinform.scot/healthy-living/weight-loss/understanding-healthy-weight/how-do-i-measure-my-body-mass-index-bmi https://www.nbt.nhs.uk/bristol-centre-enablement https://www.nbt.nhs.uk/bristol-centre-enablement https://www.porthosp.nhs.uk/departments-and-services/portsmouth-enablement-centre 3 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 pelvis and trunk: bilaterally on the anterior superior iliac spine (asis), posterior superior iliac spine (psis), and iliac crest (ic), plus spinous processes at s1, t12, and c7 (figure 1). markers were affixed directly to the participants’ skin with double-sided adhesive tape to avoid movement relative to the underlying anatomical landmarks during motion capture. for the three transfemoral amputees, the pelvis markers were instead placed on the prosthetic suspension belt (tes suspension belt, ortho europe, uk). each participant completed repeated sessions at approximately the same time of day to minimize withinsubject variability, however, session times were not standardized across participants due to the use of two clinics and room availability. • session 1: 3-6 months post-amputation (3.9 ± 1.1 months): one 10-second static standing trial (static 1) was recorded. at this time, all participants had commenced rehabilitation and were able to ambulate safely with their prosthesis. • session 2: ≥ 3 months later; range 7–16 months (13.1 ± 2.7 months). three 10-second static standing trials were recorded: o static 2: initial standing trial with full marker set. o static 3: after removing/reapplying all markers except ics (after 10-minute rest). o static 4: after 12 walking gait trials (≈ 30 minutes after static 2), markers unchanged. ic markers were retained in session 2 to provide a consistent reference point for calculating placement error when the remaining pelvic markers were reapplied. data analysis markers were labelled in qualisys track manager (qualisys, sweden). opensim 4.5 was then used to create a skeletal model of the pelvis and trunk segments, which was scaled to each participant’s standing calibration trials for each session. the pelvis segment was defined by the bilateral asis and psis markers, with the ic markers used as additional references as mentioned previously. the trunk segment was defined using the spinous process markers at s1, t12 and c7. the 3d euclidean distances were calculated between pelvis markers, including the distances between the asis and psis markers and the fixed iliac crest markers (figure 1). additionally, pelvis (relative to the global reference system) and trunk (relative to the pelvis segment) joint angles were calculated for the standing calibration trials. statistical analysis the reliability of marker placement and pelvis and trunk kinematic parameters was assessed using the icc from a two-way random model (icc2,k) and standard error of measurement (sem). icc thresholds were considered: poor (< 0.50), moderate (0.50–0.75), good (0.75–0.90), and excellent (> 0.90).12 for this study, an icc value ≥ 0.70 was deemed acceptable.9-11 this threshold has also been applied in previous research examining marker placement during gait analysis, a methodology closely related to the present study.10 standard error of measurement (sem) was calculated as the square root of the mean square error term from a repeated measures anova.13 pelvis and trunk angle errors (%) were calculated as the absolute difference in range of motion (rom) between repeated measurements, expressed as a percentage of the rom of the first measurement. this method was used for both withinsession comparisons (repeated trials within the same session) and between-session comparisons (measurements from different sessions). all analyses were performed in matlab® r2021b (mathworks, inc., usa). figure 1: marker placement positions is represented from the posterior view in the full body diagram on the left. marker details and 3d euclidean distances are listed and represented in the right side of the picture. marker number marker name markers distances 1 c7 a = lpsis-rpsis 2 t12 b = lpsis-lic 3 s1 c = lasis-lic 4 lasis d = lasis-rasis 5 rasis e = rpsis-ric 6 lic f = rasis-ric 7 ric g = lasis-lpsis 8 lpsis h = rasis-rpsis 9 rpsis left view posterior view right view anterior view https://doi.org/10.33137/cpoj.v8i2.46063 4 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 results within-session results within-session iccs for pelvis marker distances (session 2, statics 2–4) ranged from 0.78–1.00, indicating good to excellent reliability, with the highest reliability coefficients measured for lasis-rasis and lasis-lpsis distances (table 2; appendix 1). asis–ic and psis–ic distances had sems < 4 mm (table 3). pelvis angles had iccs averaging 0.71 ± 0.19, with tilt and list both ≥ 0.70 (appendix 2) and sems < 5°. static trials 3 and 4 differed by < 0.5° for all pelvis angles. for trunk range of motion parameters, all parameters displayed sem values below 5°, however trunk rotation showed the lowest icc values (table 2; appendix 3). table 2: reliability indices (icc) of asis and psis marker placement euclidean distances, and pelvis and trunk kinematic parameters. values represent the range of iccs observed within and between-sessions across static trials. icc: intraclass correlation coefficient; icc values of ≤ 0.70 are presented in bold. between-session results between-session reliability (session 1 vs. 2) showed lower iccs (table 2; appendix 4), ranging from 0.14–0.76, though sems remained acceptable. the lowest icc value (0.14) was for lpsis–rpsis distance. left and right asis distance had the highest sem (5.5 mm), suggesting more variation across timepoints (table 3), although kinematic measurements consistently reported very small sems. pelvis and trunk parameters had low iccs (appendix 5 and appendix 6), but sems remained <5° (table 4). discussion this study assessed the withinand between-assessor reliability of pelvis marker placement and kinematics in individuals with lla, a population with anatomical and practical challenges limiting accurate and consistent marker positioning. within-session pelvis marker distances showed good to excellent reliability (iccs ≥ 0.78), supporting use in a singleday or repeated trials. between-session reliability was lower (iccs as low as 0.14), especially for psis markers, likely due to anatomical variation, prosthetic interfaces, and increased adiposity obscuring landmarks. in this context, “prosthetic interfaces” refers to the components of the prosthetic socket and suspension system that interface with the residual limb. these interfaces can alter the positioning or soft tissue conformation around the pelvis between sessions, especially for transfemoral amputees. despite this, sems remained low (< 4 mm), indicating limited absolute error. the time gap between testing sessions 1 and 2 (ranging from three to six months post-amputation for the initial session to seven months or more for the follow-up) may have contributed to the observed inconsistencies. in addition, changes in static standing posture due to the prosthetic limb, body mass fluctuations (change of up to 2.4 kg between sessions in the current study), prosthetic measure within-session icc betweensession icc lasis-lic 0.78-0.81 rasis-ric 0.78-0.97 lpsis-lic 0.90-0.98 rpsis-ric 0.82-0.91 lasis-rasis 0.94–1.00 0.68–0.76 lpsis-rpsis 0.80–0.97 0.14–0.34 lasis-lpsis 0.95–1.00 0.68–0.71 rasis-rpsis 0.97–0.98 0.59–0.67 pelvis tilt 0.79–0.95 0.23–0.23 pelvis list 0.81–0.91 -0.04–0.01 pelvis rotation 0.43–0.70 -0.17–0.41 trunk flexion/extension 0.75–0.85 -0.01–0.17 trunk lateral bending 0.74–0.95 0.15–0.32 trunk rotation 0.49–0.84 -0.13–0.29 table 3: euclidean distances reported in mm as mean ± standard deviation and standard error of measurement (sem) calculated between and within sessions. distance static 1 static 2 static 3 static 4 sem (within) sem (between) lasis-lic 107.2 ± 26.0 118.0 ± 29.9 118.0 ± 29.4 2.4 rasis-ric 104.0 ± 26.3 102.3 ± 24.1 103.6 ± 25.7 2.6 lpsis-lic 195.1 ± 22.8 194.0 ± 24.2 194.2 ± 26.4 1.7 rpsis-ric 209.5 ± 26.3 209.4 ± 19.9 213.0 ± 20.3 2.0 lasis-rasis 326.8 ± 59.7 326.9 ± 42.3 326.9 ± 47.0 327.9 ± 46.3 2.3 5.5 lpsis-rpsis 81.6 ± 17.9 85.7 ± 15.1 88.5 ± 11.7 88.9 ± 11.1 1.3 2.7 lasis-lpsis 257.7 ± 34.6 252.7 ± 29.4 256.2 ± 33.1 256.7 ± 32.9 1.3 3.6 rasis-rpsis 259.5 ± 32.1 260.4 ± 28.6 259.0 ± 29.0 262.4 ± 28.5 1.2 3.6 https://doi.org/10.33137/cpoj.v8i2.46063 5 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 discomfort, and fatigue, along with external factors like suspension systems or high bmi, may have affected consistent marker placement and segment orientation across sessions on a population level. these factors can obscure anatomical landmarks and cause marker displacement — especially over longer intervals between assessments — reducing the reliability of pelvis and trunk kinematics. this likely contributed to the high placement variability observed in our study (standard deviations: 11.1– 59.7 mm), which exceeds the 10–12 mm values reported in healthy individuals, where variability is primarily attributed to soft tissue artifact.4 in our case, marker placement also affected joint angles calculation during dynamic trials. between-session pelvis errors were 18% (tilt), 20% (list), and 10% (rotation), versus within-session errors of 10%, 7%, and 2%. trunk angles showed even greater variability, with between-session errors of 22%, 34%, and 61%, and within-session errors of 6%, 18%, and 37%. subtracting a standing baseline from pelvis and trunk kinematics could reduce the apparent variability in walking trials by accounting for inter-session or inter-trial differences in participants’ neutral posture. because trunk angles were calculated relative to the pelvis, any variation in pelvic orientation during standing contributes directly to trunk angle variability. by referencing walking kinematics to a consistent static posture, betweenand within-session errors in both pelvis and trunk angles might be reduced, particularly for rotational measures, as individual differences in habitual standing alignment would be removed. however, this approach would not eliminate variability due to marker placement, soft tissue artifact, or dynamic postural adjustments during gait. trunk and pelvis kinematic analysis observed during the static trials revealed additional reliability concerns. pelvis and trunk rotation angles showed low within-session reliability during session 2 (static 2 vs static 4), with iccs of 0.43 and 0.50, respectively. because trunk angles were calculated relative to the pelvis, variability in pelvic orientation likely contributed to the greater variability observed in trunk rotation measures. fatigue, particularly in the residual limb hip flexors, may prompt compensatory strategies such as increased pelvic rotation toward the sound limb to maintain static balance and reduce muscular effort during standing. discomfort or pain within the prosthetic socket during repeated walking trials can further contribute to asymmetrical weight distribution and postural adjustments, leading to pelvis and trunk rotation toward the sound limb during the final static trial. although sem values for pelvis and trunk angles remained below 5° when comparing the 2 sessions, indicating good absolute reliability, icc values were low (table 4). this likely reflects variability in participants’ static postures between sessions, which can affect icc due to its sensitivity to between-subject variance.14 while icc captures the proportion of variance due to true individual differences, inconsistent baseline positioning can reduce its values despite reliable within-subject measurements. in contrast, sem reflects the within-subject consistency of repeated measurements and is unaffected by between-subject variability.13 thus, the low iccs likely result from postural variability rather than poor reliability. it is also important to consider that the 5° threshold used to interpret sem values is often applied in studies involving lower extremity joint angles which typically exhibit a much larger range of motion than the pelvis or trunk.10 therefore, in these regions, even small absolute errors can be proportionally significant. despite this, the consistently low sem values observed still indicate good within-subject reliability and interpreting sem alongside icc offers a more complete assessment of measurement reliability. although each participant completed repeated sessions at approximately the same time of day to minimize withinsubject variability due to prosthetic discomfort or fatigue, session times were not standardized across participants, which may have contributed to between-subject variability in marker placement and segment orientation. static 1 was used as the baseline measurement for marker placement; however, it is possible that marker positioning in this trial was not fully representative of the participant’s true anatomical alignment. using an average of multiple static trials (e.g. static 1–3) might have provided a more stable baseline, potentially reducing variability in subsequent measures. table 4: pelvis and trunk kinematics for the pelvis and the trunk segments, in degrees as mean ± standard deviation and standard error of measurement (sem) calculated between and within sessions. pelvis/trunk kinematics static 1 static 2 static 3 static 4 sem (within) sem (between) mean pelvis tilt 7.7 ± 13.1 -0.7 ± 6.3 0.6 ± 4.9 0.2 ± 5.9 0.54 1.50 mean pelvis list 1.1 ± 5.1 2.9 ± 3.4 2.3 ± 3.3 2.6 ± 3.4 0.31 0.84 mean pelvis rotation 3.1 ± 4.0 1.6 ± 3.0 0.1 ± 3.9 0.1 ± 3.5 0.57 0.75 mean trunk flexion -0.3 ± 0.3 -0.2 ± 0.1 -0.2 ± 0.1 -0.2 ± 0.1 0.01 0.04 mean trunk list -0.0 ± 0.1 -0.0 ± 0.1 -0.0 ± 0.1 -0.0 ± 0.1 0.01 0.01 mean trunk rotation 0.1 ± 0.2 0.0 ± 0.1 0.0 ± 0.1 0.0 ± 0.1 0.01 0.03 https://doi.org/10.33137/cpoj.v8i2.46063 6 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 conclusion overall, findings support the reliability of pelvis marker placement and posture within a session in lla populations but highlight challenges for between-session consistency, relevant for longitudinal studies. to improve consistency, we recommend collecting multiple trials per session, documenting prosthetic configuration, and standardizing participant posture using photographs or guides. static trials remain useful for estimating segment lengths but may reflect habitual or compensatory postures rather than neutral alignment. researchers should account for this when interpreting static kinematics. ultimately, reliable gait analysis in lla populations requires careful marker protocols, posture control, and awareness of static calibration limitations across timepoints. acknowledgements we thank the clinicians dr shigong gou and helen harvey (bristol centre for enablement), and chantel ostler (portsmouth enablement centre) for their feedback developing the inclusion/exclusion criteria for the study. we also thank the physiotherapists anne harrill (bristol centre for enablement) and matthias wright (portsmouth enablement centre) for their help with identifying patients who meet the inclusion criteria and coordinating patient bookings, and all the patients who took part in the study. declaration of conflicting interests the authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. consent for publication informed written consent for publication of individual person’s data in this manuscript was obtained. authors’ contribution • alexandra withey: conceptualization, methodology, writing original draft, writing review & editing. • dario cazzola: methodology, writing review & editing, supervision. • abby tabor: methodology, writing review & editing, supervision. • elena seminati: conceptualization, methodology, writing review & editing, supervision. all authors read and approved the final manuscript. sources of support this study has funding through the university research studentship award (ursa) awarded by the university of bath. the funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. references 1.gorton iii ge, hebert da, gannotti me. assessment of the kinematic variability among 12 motion analysis laboratories. gait posture. 2009; 29:398–402. https://doi.org/10.1016/j.gaitpost. 2008.10.060 2.hamill j, selbie ws, kepple tm. three-dimensional kinematics. in: robertson dg, caldwell ge, hamill j, kamen g, whittlesey sn, editors. research methods in biomechanics. 2nd ed. champaign (il): human kinetics; 2013. p. 35–60. 3.robertson dge, caldwell ge, hamill j, kamen g, whittlesey sn. research methods in biomechanics. 2nd ed. champaign (il): human kinetics; 2014. 4.fonseca m, gasparutto x, grouvel g, bonnefoy-mazure a, dumas r, armand s. evaluation of lower limb and pelvic marker placement precision among different evaluators and its impact on gait kinematics computed with the conventional gait model. gait posture. 2023; 104:22–30. https://doi.org/10.1016/j.gaitpost. 2023.05.028 5.kurdibaylo sf. obesity and metabolic disorders in adults with lower limb amputation. j. rehabil. res. dev. 1996; 33:387–394. 6. mollee ts, dijkstra pu, dekker r, geertzen jh. the association between body mass index and skin problems in persons with a lower limb amputation: an observational study. bmc musculoskelet disord. 2021; 22(1):769. 7.lerner zf, board wj, browning rc. browning, effects of an obesity-specific marker set on estimated muscle and joint forces in walking. med sci sports exerc. 2014; 46(6):1261-7. https://doi.org/10.1249/mss.0000000000000218 8.peters a, galna b, sangeux m, morris m, baker r. quantification of soft tissue artifact in lower limb human motion analysis: a systematic review. gait posture. 2010; 31:1–8. https://doi.org/10.1016/j.gaitpost.2009.09.004 9.cicchetti dv. guidelines, criteria, and rules of thumb for evaluating normed and standardized assessment instruments in psychology. psychol assess. 1994; 6:284–90. https://doi.org/10.1037/1040-3590.6.4.284 10.horsak b, pobatschnig b, baca a, greber-platzer s, kreissl a, nehrer s, et al. within-assessor reliability and minimal detectable change of gait kinematics in a young obese demographic. gait posture. 2017; 54:112–8. https://doi.org/10.1016/j.gaitpost. 2017.02.028 11.koo tk, li my. a guideline of selecting and reporting intraclass correlation coefficients for reliability research. j chiropr med. 2016; 15:155–63. https://doi.org/10.1016/j.jcm.2016.02.012 12.portney lg, watkins mp. foundations of clinical research: applications to practice. upper saddle river, nj: pearson/prentice hall; 2009. 13.atkinson g, nevill am. statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine. sports med. 1998; 26(4):217-38. https://doi.org/10.2165/00007256-199826040-00002 14.weir jp. quantifying test-retest reliability using the intraclass correlation coefficient and the sem. j strength cond res. 2005; 19(1):231-40. https://doi.org/:10.1519/15184.1 https://doi.org/10.33137/cpoj.v8i2.46063 https://doi.org/10.1016/j.gaitpost.%202008.10.060 https://doi.org/10.1016/j.gaitpost.%202008.10.060 https://doi.org/10.1016/j.gaitpost.%202023.05.028 https://doi.org/10.1016/j.gaitpost.%202023.05.028 https://doi.org/10.1249/mss.0000000000000218 https://doi.org/10.1016/j.gaitpost.2009.09.004 https://doi.org/10.1037/1040-3590.6.4.284 https://doi.org/10.1016/j.gaitpost.%202017.02.028 https://doi.org/10.1016/j.gaitpost.%202017.02.028 https://doi.org/10.1016/j.jcm.2016.02.012 https://doi.org/10.2165/00007256-199826040-00002 https://doi.org/:10.1519/15184.1 7 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 appendix pelvis marker distances across static comparisons within sessions appendix 1: individual pelvis marker distances across sequential static posture comparisons within sessions. each subplot displays lasisrasis, lpsis-rpsis, lasis-lpsis, rasis-rpsis with corresponding intraclass correlation coefficients (icc) to indicate measurement reliability. https://doi.org/10.33137/cpoj.v8i2.46063 8 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 pelvis angles across static comparisons within sessions appendix 2: individual pelvis angles across sequential static posture comparisons within sessions. each subplot displays pelvis tilt, list, and rotation with corresponding intraclass correlation coefficients (icc) to indicate measurement reliability. https://doi.org/10.33137/cpoj.v8i2.46063 9 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 trunk angles across static comparisons within sessions appendix 3: individual trunk angles across sequential static posture comparisons within sessions. each subplot displays trunk flexion/extension, lateral bending, and rotation with corresponding intraclass correlation coefficients (icc) to indicate measurement reliability. https://doi.org/10.33137/cpoj.v8i2.46063 10 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 pelvis marker distances across static comparisons between sessions appendix 4: individual pelvis marker distances across sequential static posture comparisons between sessions. each subplot displays lasis-rasis, lpsis-rpsis, lasis-lpsis, rasis-rpsis with corresponding intraclass correlation coefficients (icc) to indicate measurement reliability. https://doi.org/10.33137/cpoj.v8i2.46063 11 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 pelvis angles across static comparisons between sessions appendix 5: individual pelvis angles across sequential static posture comparisons between sessions. each subplot displays pelvis tilt, list, and rotation with corresponding intraclass correlation coefficients (icc) to indicate measurement reliability. https://doi.org/10.33137/cpoj.v8i2.46063 12 withey a, cazzola d, tabor a, seminati e. withinand between-session reliability of pelvic marker placement and posture in lower-limb amputees. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 2. https://doi.org/10.33137/cpoj.v8i2.46063 canadian prosthetics & orthotics journal issn: 2561-987x reliability of pelvic markers and posture in lower-limb amputees withey et al., 2025 trunk angles across static comparisons between sessions appendix 6: individual trunk angles across sequential static posture comparisons between sessions. each subplot displays trunk flexion/extension, lateral bending, and rotation with corresponding intraclass correlation coefficients (icc) to indicate measurement reliability. https://doi.org/10.33137/cpoj.v8i2.46063 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 7, issue 2 2024 research article azizi s, moradi v, hajiaghaei b, babaee t. prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists: a study on workrelated quality of life. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.6. https://doi.org/10.33137/cpoj.v7i2.44064 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://doi.org/10.33137/cpoj.v7i2.44064 1 azizi s, moradi v, hajiaghaei b, babaee t. prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists: a study on workrelated quality of life. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 6. https://doi.org/10.33137/cpoj.v7i2.44064 research article prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists: a study on work-related quality of life azizi s1, moradi v2, hajiaghaei b1, babaee t.1* 1 department of orthotics and prosthetics, school of rehabilitation sciences, iran university of medical sciences, tehran, iran. 2 iran-helal institute of applied science and technology, tehran, iran. introduction work-related musculoskeletal injuries are among the most severe occupational issues worldwide. unfavorable body position during work is an essential factor in these injuries. according to the health and safety executive, 38% of workrelated problems are related to musculoskeletal disorders,1 the leading cause of more than half of work absences and about 50% of occupational diseases.2 these disorders are more frequently observed in occupations that require manual work, lifting heavy objects, or performing repetitive movements.3 adjusting work habits, reducing working hours, or changing job types can help mitigate these issues.4,5 demographic characteristics such as age, gender, and psychosocial factors are some predicting variables for musculoskeletal disorders.6 these disorders lead to waste of working days, increased costs, and human injuries and are the leading cause of disability.7 workrelated musculoskeletal disorders reduce work efficiency and production, affecting work-related quality of life open access abstract background: work-related musculoskeletal injuries are prevalent globally and can impact both work efficiency and the quality of services offered to patients. objectives: this study investigated the prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists and its relationship with work-related quality of life. methodology: in this cross-sectional study, the persian versions of the nordic musculoskeletal questionnaire (nmq) and work-related quality of life (wrqol) scale were used to identify disorders of different body parts and occupational quality of life. a group of 263 orthotists and prosthetists were invited to complete the questionnaires using a simple random sampling method. the data from 188 respondents were analyzed. the association between wrqol and the following variables: gender, work experience, age, presence of musculoskeletal disorder, and income level, was assessed using spearman’s rho correlation coefficient. findings: there was an 82% prevalence of work-related musculoskeletal disorders among the participants. the most common areas involved were the lower back (35%) and neck (28%). there was a statistically significant relationship between gender (rs(188) = 0.16, p = 0.031) and weight (rs(188) = 0.15, p = 0.045) and work-related musculoskeletal disorders, however, the strength of the correlation was very small. moreover, the wrqol had a statistically significant but small to negligible relationship with gender (rs(188) = 0.17, p = 0.016), work experience (rs(188) = 0.18, p = 0.011), age (rs(188) = 0.15, p = 0.039), and income (rs(178) = 0.17, p = 0.025). there was no significant relationship between work-related musculoskeletal disorders and the total score of wrqol scale. conclusion: while the prevalence of work-related musculoskeletal disorders is high among iranian orthotists and prosthetists, the average wrqol presents an opportunity for improvement. the findings indicate associations between work-related disorders and factors such as gender, work experience, age, and income, emphasizing the need for plans to improve working conditions and prevent these disorders. conducting ergonomic assessments of workstations, increasing employee income, and implementing training programs that focus on proper lifting techniques, posture, and the use of ergonomic tools may help reduce work-related musculoskeletal disorders in orthotists and prosthetists. article info received: october 8, 2024 accepted: january 27, 2025 published: february 2, 2025 citation azizi s, moradi v, hajiaghaei b, babaee t. prevalence of workrelated musculoskeletal disorders among iranian orthotists and prosthetists: a study on workrelated quality of life. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 6. https://doi.org/10.33137/cpoj.v7i2 .44064 keywords musculoskeletal disorder, work, quality of life, orthotist, wrqol, rehabilitation, musculoskeletal, prosthetist, iranian * corresponding author: dr. taher babaee, phd, cpo affiliation: department of orthotics and prosthetics, school of rehabilitation sciences, iran university of medical sciences, tehran, iran. e-mail: babaee.t@iums.ac.ir orcid id: https://orcid.org/0000-0002-1487-2374 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 2, article no. 6, 2024 https://doi.org/10.33137/cpoj.v7i2.44064 https://doi.org/10.33137/cpoj.v7i2.44064 https://doi.org/10.33137/cpoj.v7i2.44064 mailto:babaee.t@iums.ac.ir https://orcid.org/0000-0002-1487-2374 https://jps.library.utoronto.ca/index.php/cpoj/index 2 azizi s, moradi v, hajiaghaei b, babaee t. prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists: a study on workrelated quality of life. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 6. https://doi.org/10.33137/cpoj.v7i2.44064 canadian prosthetics & orthotics journal issn: 2561-987x musculoskeletal disorders among iranian orthotists and prosthetists azizi et al., 2024 (wrqol).8 issues related to wrqol of employees affect their job satisfaction and their intention to stay on the job.9 quality of working life (qowl) focuses on different factors that affect a person's work experience and overall wellbeing. these include the physical work environment, the social atmosphere within the organization, conflicts related to work roles, job enrichment, fair compensation, flexible work hours, reward systems, the balance between work and family life, job security, and overall productivity and health.10 the connection between work-related stress and the broader idea of qowl has been examined, revealing a link between job stress and burnout as significant negative factors affecting overall quality of life.11 orthotists and prosthetists, as well as medical personnel, are at a higher risk of suffering from musculoskeletal disorders due to repetitive tasks, high workload, poor working conditions, psychological factors such as occupational stress, and work shifts.12 manual handling of heavy plaster casts (sometimes more than 25 kg), limited resting time between activities, working in a limited workspace, and not having a helping hand to lift heavy objects imposes a high physical load on the musculoskeletal structure of these people.13,14 therefore, the possibility of musculoskeletal disorders is high among orthotists and prosthetists due to long hours and heavy work, use of inappropriate and non-standard tools and machines, and lack of knowledge of the correct physical position.15 it has been reported that the prevalence of back disorders in manual labor is eight times higher than in occupations that do not involve manual work.16 in their study of 173 orthotists and prosthetists, anderson et al. found that 76% of participants experienced musculoskeletal pain within the previous six months.17 concerns related to workload, tight deadlines, and a poorly designed physical environment can increase fatigue and stress levels.9 prosthetists and orthotists reported that the demands imposed by other healthcare staff and patients not only added to their workloads but also created unrealistic time constraints for task completion.13 occupational pressures and injuries can negatively affect the services provided by healthcare personnel for society. this indicates the importance of and needs to consider the physical and mental health of the personnel working in health and treatment centers.18 since the workstations in orthotics and prosthetics wards are non-adjustable and individuals of various heights and body dimensions must work at the same workstation, this situation can lead to the development of improper postures in the neck, shoulders, and back.14 they seem to be the main contributors to morbidity and disability in any workforce, affecting individuals' quality of life and work capacity.19 to the best of our knowledge, no studies have assessed wrqol among orthotists and prosthetists. various studies have been conducted to investigate the prevalence of work-related musculoskeletal disorders in iran. however, there are no accurate statistics on the prevalence of work-related musculoskeletal disorders and the quality of life of people working in this field of rehabilitation in iran. this study aimed to determine the prevalence of work-related musculoskeletal disorders among orthotists and prosthetists and investigate its relationship with wrqol. methodology this cross-sectional study was conducted from july 2023 to november 2023. data was collected in person and online. to increase the generalizability of the study findings, the orthotists and prosthetists from all over iran were invited to participate. consequently, individuals working in tehran, iran, completed the questionnaires in person, while those situated other cities/provinces filled out the questionnaires online. it is important to note that the items in the questionnaires completed in person and online were exactly the same. before completing the questionnaire, participants were given a consent form to sign. for the online version, an invitation message was sent via whatsapp to individuals who had smartphones and internet access. the invitation included a brief description of the study and a link to the questionnaire. consent was obtained by including a statement at the beginning of the online survey. the software used (https://porsline.ir) automatically removed respondents' phone numbers, ensuring that participants remained anonymous during the statistical analyses. the study protocol was approved by the research ethics committee of iran university of medical sciences (ref: # ir.iums.rec.1402.141, date: 24/05/2023). the participants were asked to answer the persian versions of the nordic musculoskeletal questionnaire (nmq)20 and the wrqol scale.21 completing these questionnaires took about seven minutes on average. the nmq is among the most commonly utilized questionnaires for evaluating work-related musculoskeletal disorders. it has proven to be highly reliable in assessing ergonomic hazards across different healthcare professionals.22 the wrqol scale is widely recognized for its comprehensive approach to assessing various dimensions of factors across both work and non-work life domains.23 the nmq and wrqol scales are tools that broadly assess work-related musculoskeletal disorders and the quality of life of individuals across various professions. the inclusion criteria included working as an orthotist or prosthetist at the time of the study,24 having at least one year of clinical work experience,25 having a smartphone, and having no previous musculoskeletal injuries during the past 12 months.14 to assess the participants’ previous musculoskeletal injuries, the following question was asked: “have you experienced injuries in your neck, shoulders, elbows, wrists, upper back, waist, thighs, knees, or ankles https://doi.org/10.33137/cpoj.v7i2.44064 https://porsline.ir/ 3 azizi s, moradi v, hajiaghaei b, babaee t. prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists: a study on workrelated quality of life. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 6. https://doi.org/10.33137/cpoj.v7i2.44064 canadian prosthetics & orthotics journal issn: 2561-987x musculoskeletal disorders among iranian orthotists and prosthetists azizi et al., 2024 during the past 12 months?”. those cases who did not complete the questionnaires were excluded. nordic musculoskeletal questionnaire this questionnaire is used in work-related healthcare studies to evaluate the prevalence of musculoskeletal disorders. the first part includes nine questions about pain and discomfort experienced in the past 12 months, the second part consists of nine questions about pain and discomfort experienced in the last seven days, and the third part consists of nine questions about reducing working hours and leaving the workplace due to pain and discomfort experienced in the past 12 months. all items are answered with "yes” or “no". if participants answered "yes," they were then asked whether the musculoskeletal pain had been present in the past 7 days (yes or no) and whether the musculoskeletal pain had hindered their ability to engage in regular work and daily activities over the past 12 months (yes or no). it is used to collect information on pain or discomfort in nine body parts: neck, shoulder, elbow, wrist, upper back, waist, thigh, knee, and ankle.18,26 the validity and reliability of its persian version have been evaluated by namnik et al. showing an acceptable internal consistency of more than 0.7, a standard error of measurement ranging 0.56 to 1.76, and a kappa coefficient ranging 0.78 to 1).20 the wrqol scale this questionnaire, designed by van laar and easton in 2007, measures the qowl.27 it consists of 24 items distributed into six subgroups to evaluate wrqol. the scoring is based on a 5-point likert scale. twenty-three items evaluate six subgroups: general well-being, homework interface, job-career satisfaction, control at work (referring to the degree of autonomy and influence an employee has over their work environment and tasks), working conditions, and stress at work. item 24 evaluates satisfaction with the work-related quality of work. the full scale score of this questionnaire is obtained by calculating the average score from these six areas, ranging from 1 to 110, where a score of 1 to 71 indicates the lowest level of wrqol and a score of 85 to 110 shows the highest level of wrqol.27 percentile equivalents of each wrqol subscale are also categorized as low qowl (score range of 10-30), medium qowl (score ranges of 40-60), and high qowl (score range of 70-99). higher percentiles indicate a better qowl. the validity and reliability of its persian version have been investigated by shabaninejad et al.21 sampling method and sample size a simple random sampling method was employed to include potential participants. the following formula28 was considered for sample size calculation: 𝑛 = 𝑍2p(1−p) 𝑑2 where n is the sample size, z is the statistic corresponding to the level of confidence (99%), p is expected prevalence (60%),29 and d is precision (0.1); at least 159 participants were required. considering that the average response rate for surveys among healthcare professionals is 53.3%,30 a total of 263 orthotists and prosthetists were invited to participate in this study. statistical analysis descriptive data (means and standard deviations) and frequencies were reported for continuous and categorical variables, respectively. to check the normality of the data, the kolmogorov-smirnov test was run. the association between wrqol and the following variables: gender, work experience, age, presence of musculoskeletal disorder, and income level, was assessed using spearman’s rho correlation coefficient. we considered the relationships as good to excellent, moderate to good, small, and small to no correlation if the r values were (r > 0.75), (0.50 < r < 0.75), (0.25 < r < 0.50), and (r < 0.25), respectively.31 the mannwhitney u test was used for data that did not follow a normal distribution, while the independent-sample t-test was applied to normally distributed data. these tests compared the mean values of wrqol parameters between men and women. the chi-square test was used to assess the relationships between categorical variables. all data were analyzed using the statistical package for social sciences (spss) software version 20. a threshold of 0.05 was considered as significant. results a total of 263 orthotists and prosthetists were invited to participate in the study, either in-person or online. of these, 207 completed the questionnaires, yielding a response rate of 78%. after applying the inclusion and exclusion criteria, the data from 188 participants (75 men and 113 women) were chosen and analyzed. orthotists and prosthetists from various centers across different cities in iran participated in this study. the mean of age, height, and weight of the participants were 31.4 ± 8.3 years old (range of 21 to 60 years old), 173.3 ± 9.5 cm (range of 150 to 197 cm), and 75.1 ± 14.6 kg (range of 45 to 110 kg). one hundred and four people were single, and 84 people were married. their average daily working hours was 7.2 ± 2.8 hours (range of 1 to 15 hours), the average work experience was 7.4 ± 7.8 years (range of 1 to 34 years), and the average number of visitors per week was 26.2 ± 27.3 (range of 2 to 200 patients). as shown in table 1, most participants worked in private clinics. additionally, 40.4% of all participants engaged in activities outside of working hours, while 52.7% participated in sports activities. a total of 141 orthotists and 47 prosthetists participated in the study. the prevalence rates of musculoskeletal disorders among the studied orthotists and prosthetists were 82% and 81%, respectively. 123 people (65.4%) stated that they felt pain, discomfort, burning, or numbness in different body parts during the last seven days. https://doi.org/10.33137/cpoj.v7i2.44064 4 azizi s, moradi v, hajiaghaei b, babaee t. prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists: a study on workrelated quality of life. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 6. https://doi.org/10.33137/cpoj.v7i2.44064 canadian prosthetics & orthotics journal issn: 2561-987x musculoskeletal disorders among iranian orthotists and prosthetists azizi et al., 2024 table 1: percentage of participants by out-of-work activities and workplace type. sport activities activities out of working hours workplace yes no yes no private clinic government work environment both government work environment and private clinic personal practice 52.7% 44.7% 40.4% 59.6% 68.1% 8.5% 9.6% 26.8% table 2: prevalence of musculoskeletal disorders in the past 12 months and 7 days, and the percentage of individuals requiring reduced activity or workplace leave. musculoskeletal disorders frequency, n (%), in last 12 months musculoskeletal disorders frequency, n (%), in last 7 days reduced activity or leave the workplace frequency, n (%), in last 12 months body segments 53 (28.2%) 40 (21.3%) 14 (7.4%) neck 23 (12.2%) 17 (9%) 8 (4.3%) right shoulder 12 (6.4%) 11 (5.9%) 5 (2.7%) left shoulder 17 (9%) 11 (5.9%) 3 (1.6%) both shoulders 13 (6.9%) 11 (5.9%) 2 (1.1%) right elbow 1 (0.5%) 0 (0%) 0 (0%) left elbow 3 (1.6%) 2 (1.1%) 1 (0.5%) both elbows 30 (16%) 16 (8.5%) 9 (4.8%) right wrist/hand 6 (3.2%) 4 (2.1%) 1 (0.5%) left wrist/hand 21 (11.2%) 12 (6.4%) 2 (1.1%) both wrists/hands 33 (17.6%) 21 (11.2%) 7 (3.7%) upper back 66 (35.1%) 45 (23.9%) 14 (7.4%) lower back 8 (4.3%) 4 (2.1%) 6 (3.2%) right hip and thigh 8 (4.3%) 3 (1.6%) 8 (4.3%) left hip and thigh 7 (3.7%) 5 (2.7%) 11 (5.8%) both hips and thighs 8 (4.3%) 2 (1.1%) 3 (1.6%) right knee 10 (5.3%) 4 (2.1%) 2 (1.1%) left knee 23 (12.3%) 10 (5.3%) 6 (3.2%) both knees 6 (3.2%) 2 (1.1%) 0 (0%) right ankle and foot 10 (5.3%) 5 (2.7%) 2 (1.1%) left ankle and foot 40 (21.3%) 30 (16%) 9 (4.8%) both ankles and feet table 3: subscales scores of work-related quality of life scale in studied population. full-scale wrqol general wellbeing home-work interface job-career satisfaction control at work working conditions stress at work work related quality of life subscales 79.44 ± 10.70 19.41 ± 3.47 9.62 ± 2.53 20.41 ± 4.06 14.22 ± 1.88 9.84 ± 2.45 5.92 ± 1.94 mean ± sd medium low low medium high low medium percentile equivalents* * the percentile ranges for low, medium, and high qowl is 10-30, 40-60, and 70-99, respectively. table 4: relationship between work-related quality of life subscales and parameters of interest. work experience age income the average number of visits per week wrqol subscales r p r p r p r p 0.24 0.01 0.26 0.01 0.21 0.77 0.13 0.04 general well-being 0.06 0.39 0.07 0.29 0.16 0.02 -0.06 0.41 home-work interface 0.15 0.04 0.11 0.12 0.09 0.20 -0.09 0.21 jobcareer satisfaction -0.04 0.95 -0.01 0.85 0.09 0.22 0.03 0.66 control at work 0.15 0.03 0.09 0.21 0.07 0.33 0.01 0.83 working conditions -0.15 0.03 -0.15 0.03 0.08 0.28 0.06 0.4 stress at work 0.18 0.01 0.15 0.03 0.16 0.02 0.03 0.63 full scale wrqol https://doi.org/10.33137/cpoj.v7i2.44064 5 azizi s, moradi v, hajiaghaei b, babaee t. prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists: a study on workrelated quality of life. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 6. https://doi.org/10.33137/cpoj.v7i2.44064 canadian prosthetics & orthotics journal issn: 2561-987x musculoskeletal disorders among iranian orthotists and prosthetists azizi et al., 2024 also, 77 people (41%) were forced to rest, reduce work activity, leave the workplace, or could not perform their activities at work or home during the past 12 months due to pain or discomfort (table 2). results of chi-square test revealed that there was a significant relationship between the participants' gender and musculoskeletal disorders in the last 12 months (phi = 0.157, p = 0.031). there was a small to no relationship between participants’ weight and musculoskeletal disorders in the last 12 months (rs(188) = 0.14, p = 0.045). the prevalence of these disorders was higher in men than women (89% versus 76%) and people with more weight. decreased work activity, leaving the workplace, or being unable to perform activities at home or the workplace during the last 12 months had a statistically significant yet small to negligible relationship with the number of daily working hours (rs(188) = 0.22, p = 0.002). among the different areas of wrqol, control at work (14.22 ± 1.88) had the highest mean, home-work interface (9.62 ± 2.53), and working conditions (9.84 ± 2.45) had the lowest mean, and the mean of wrqol was 79.44 ± 10.70 (table 3). the wrqol had a small to negligible but significant relationship with gender (rs(188) = 0.17, p = 0.016), work experience (rs(188) = 0.18, p = 0.011), age (rs(188) = 0.15, p = 0.039), and income (rs(178)= 0.17, p =0.025) (table 4). the wrqol was higher in women than in men. all areas of the quality of work life had a higher mean in women than men, except stress at work (table 5). there was no statistically significant relationship between general musculoskeletal disorders and overall wrqol. still, these disorders were significantly related to general well-being (rs(188) = 0.16, p= 0.023). discussion this study investigated the prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists and its relationship with wrqol. the results showed a high prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists who had a minimum one year of clinical experience. 82% of the studied orthotists and prosthetists had experienced pain in different body parts during the past 12 months. this was in line with anderson et al.'s study on australian orthotists and prosthetists (80%).24 still, the prevalence of musculoskeletal pain found in this study was higher than that reported by farahmand et al., who noted that 60% of orthotists experienced pain in their shoulders, elbows, and wrists over the last year. in contrast, the prevalence of musculoskeletal pain among prosthetists was 33%.29 notably, this study found that the prevalence of musculoskeletal pain was the same for both orthotists and prosthetists. some factors contributing to musculoskeletal disorders in orthotists and prosthetists include the poor design of tools and machinery, long working hours using them, manual lifting and moving of heavy objects (such as molded plaster) without assistance, working with vibrating devices (like milling machines and drills) and performing repetitive tasks.29 findings from this study showed that pain is most prevalent in the back (35.1%), neck (28.2%), and ankles and feet (21.3%), with lower back pain being the most common musculoskeletal disorder among orthotists and prosthetists. in the study by anderson et al.,16 it was reported that the prevalence of disorders in the lumbar region is eight times higher in jobs involving manual activity compared to jobs that do not require manual activity. the manual handling of heavy plaster molds for various processes such as mold correction, lamination, thermoplastic mold production, and the preparation of negative and positive plaster molds, as well as filling the molds, is common in orthotic and prosthetic fabrication facilities. these factors may explain the high prevalence of back pain among orthotists and prosthetists. there seems to be a small to negligible yet statistically significant relationship between gender and musculoskeletal disorders, as the findings of this study show that the prevalence of these disorders is higher in men. this may be due to the fact that men tend to be more inclined to perform heavier lifts. the results of this study are in line with farahmand et al.'s findings.29 however, in other studies, such as those by anderson et al. on australian orthotists and prosthetists,24 rahimi et al. on iranian physiotherapists,32 nazari et al. on occupation therapists,33 table 5: comparing the results of work-related quality of life subscales between men and women. p women men wrqol subscales mean ± sd quality of work life mean ± sd quality of work life 0.04 19.83 ± 3.31 medium 18.78 ± 3.64 low general well-being 0.51 9.67 ± 2.35 low 9.54 ± 2.80 low home-work interface 0.01 21.00 ± 3.64 medium 19.52 ± 4.50 medium job-career satisfaction 0.01 14.53 ± 1.57 high 13.77 ± 2.20 high control at work 0.26 10.02 ± 2.15 low 9.56 ± 2.83 low working conditions 0.47 5.88 ± 1.99 medium 5.98 ± 1.87 medium stress at work 0.01 80.95 ± 9.12 medium 77.17 ± 12.45 medium full scale wrqol https://doi.org/10.33137/cpoj.v7i2.44064 6 azizi s, moradi v, hajiaghaei b, babaee t. prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists: a study on workrelated quality of life. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 6. https://doi.org/10.33137/cpoj.v7i2.44064 canadian prosthetics & orthotics journal issn: 2561-987x musculoskeletal disorders among iranian orthotists and prosthetists azizi et al., 2024 and keyhani et al. on iranian dentists,34 the prevalence of work-related musculoskeletal disorders was higher in women. additionally, there was a small to negligible but significant relationship between weight and feeling pain and discomfort due to musculoskeletal disorders over the past 12 months. still, this study did not find a significant relationship between these disorders and other demographic characteristics such as age, height, work experience, income, and working hours. it is important to note that, due to the small to negligible relationship between gender and musculoskeletal disorders, these results should be interpreted with caution. only 52.7% of the studied orthotists and prosthetists engaged in regular sports activities and showed little tendency to reduce their activity or take rest when they felt pain and discomfort. additionally, about 48% of people who experienced pain and discomfort in the last 12 months reduced their activity during work. decreased work activity, leaving the workplace, or an inability to perform tasks at home or the workplace during the last 12 months was more common in women (57%), although this difference was not significant. these results are similar to those found in rahimi et al.’s study on iranian physiotherapists.32 the total score of the wrqol questionnaire among the studied orthotists and prosthetists was 79.44, which, based on the proposed percentile equivalents, falls within the average range. among its different aspects, control at the workplace was more favorable, and working conditions and the relationship between home and work were less favorable. also, the mean wrqol score was significantly related to gender and was higher in women. the average quality of life for female orthotists and prosthetists was higher than that of their men counterparts in all aspects except stress at work. there was a significant difference in general well-being, control at work, and job-career satisfaction between men and women. regarding the demographic characteristics and wrqol, there was a small to negligible but significant relationship between age, gender, work experience, income, and overall quality of life. the wrqol was higher in women and participants of older ages, higher income, and greater work experience. the reasons for this could include increased job satisfaction, better control of the work environment, and reduced stress because of more work experience, age, and income. arab et al. found no significant difference between age, sex, employment status, working hours, and wrqol. however, specialist physicians with the least work experience had the highest wrqol.35 in abbasi et al.'s study on nurses, age and work experience had an inverse relationship with wrqol.36 in light of the small to negligible relationship between the demographic characteristics and wrqol in this study, it is important to interpret these results cautiously. in this study, there was no significant relationship between the overall score of the wrqol and work-related musculoskeletal disorders. however, a significant relationship existed between wrqol and musculoskeletal disorders in different body areas. regarding each subdomain of wrqol, results of this study revealed a small to no relationship between general well-being and musculoskeletal disorder. it should be noted that the overall wrqol score is calculated by summing the values of its six subdomains: general well-being, home-work interface, jobcareer satisfaction, control at work, working conditions, and stress at work. consequently, the score of each subdomain influences the total score of the questionnaire. however, general well-being is an independent subdomain; its score is not affected by the scores of the other subdomains. this independence may explain the lack of a significant relationship between overall wrqol and musculoskeletal disorders, as fluctuations in other areas do not impact the general well-being score. limitations this was a cross-sectional study and, therefore, cannot show the conditions of the participants over time. also, the questions were asked about past events to evaluate the working conditions of participants (for example, in the past 12 months or seven days). thus, they may not have answered the questions accurately due to the effects of memory over time. the wrqol scale is designed without a distinction between employees and employers, so the responses might not be accurate for some questions about the work environment and the employer. moreover, in this study, there was no age limit for inclusion. most participants were under 50 years old, with 11 participants aged between 50 and 60 years. the statistical analysis revealed a small to no relationship between wrqol and participants' age. further research is needed to assess the rate of musculoskeletal injuries among orthotists and prosthetists across different age classifications and marital statuses, utilizing a sufficient sample size. in addition, this study included orthotists and prosthetists with at least one year of clinical work experience. future investigations are needed to assess the prevalence of work-related musculoskeletal disorders among novice orthotists and prosthetists with less than one year of clinical experience. conclusion there appears to be a high prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists. symptoms of pain in the back and neck are the most common issues. the iranian orthotists and prosthetists seem to have an average wrqol, which is higher in women and individuals with more work experience. addressing the high incidence of musculoskeletal disorders and enhancing the wrqol for orthotists and prosthetists may lead to improved health https://doi.org/10.33137/cpoj.v7i2.44064 7 azizi s, moradi v, hajiaghaei b, babaee t. prevalence of work-related musculoskeletal disorders among iranian orthotists and prosthetists: a study on workrelated quality of life. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no. 6. https://doi.org/10.33137/cpoj.v7i2.44064 canadian prosthetics & orthotics journal issn: 2561-987x musculoskeletal disorders among iranian orthotists and prosthetists azizi et al., 2024 outcomes and job performance in this essential healthcare sector. acknowledgements the authors would like to thank the participants for taking part in this study. declaration of conflicting interests the authors declare that there is no conflict of interest. authors’ contribution • sarina azizi: conception and design; data acquisition; analysis and interpretation; drafting the article; revision and final approval of the manuscript. • vahideh moradi: conception and design; review and final approval of the manuscript. • behnam hajiaghaei: conception and design; review and final approval of the manuscript. • taher babaee: conception and design; analysis and interpretation, revision and final approval of the manuscript. sources of support no external support 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10.15171/ijer.2019.17 35.arab m, shabaninejad h, rashidian a, rahimi a, purketabi k. a survey on working life quality of specialists working in affiliated hospitals of tums. hospital j. 2013;11(4) 36.abbasi m, zakerian a, akbarzade a, dinarvand n, ghaljahi m, poursadeghiyan m, et al. investigation of the relationship between work ability and work-related quality of life in nurses. iran j public health. 2017;46(10):1404 https://doi.org/10.33137/cpoj.v7i2.44064 https://fadavispt.mhmedical.com/book.aspx?bookid=2885 all articles are permanently available online to the public without restrictions or subscription fees. all articles are free to be used, cited, and distributed, on condition that appropriate acknowledgment is included. authors are the copyright holders of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 5, issue 2 2022 literature review carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 https://online-publication.com/wp/ http://creativecommons.org/licenses/by/4.0/ https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v5i2.39023 1 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 literature review outcome measures used to assess hand activity in amputee and intact populations: a literature review carlyle k1,2*, day s1 1 department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, united kingdom. 2 epsrc centre for doctoral training in prosthetics and orthotics, university of salford, united kingdom. introduction the hand is a complex structure responsible for powerful prehension and precise control. the range and adaptability achieved by the hand is due to the complex anatomical structure and precise control of movement and feedback by the central nervous system.1 hands are capable of determining information by allowing identification of objects by their size, shape, surface, weight, texture, and thermal properties.2 moreover, hands are crucial as terminal endeffectors in enabling people to carry out activities of daily living (adl) and participate in society.3 they are vital for carrying out basic adl such as feeding, dressing, and hygiene. additionally, hands can be used as communication tools as demonstrated through the use of sign language and touch reading, and creative tools in music and dance. if the hand is incapacitated due to trauma, tumour, infection, peripheral vascular disease, or congenital anomaly, then amputation may be the result. roughly five to six thousand amputations are undertaken in the united kingdom each year.4 of these amputations, roughly one fifth are upper limb amputations.5 a solution to assist those with amputation in carrying out adl lies in prosthetic devices. it has been noted that statistics relevant to the prevalence of limb amputation and prosthetic device provision are limited and often inconsistent.6 studies have also shown that hand prostheses prescribed to users are not reaching their open access abstract background: the human hand is critical in assisting with activities of daily living (adl). amputation of the hand can affect a person physically, socially and psychologically. knowledge of outcome measures used to assess upper limb activity of intact and amputee populations may aid in guiding research to develop applicable measurement tools specific to the amputee population. tools could aid developments in prosthetic design and prescription, which benefit both users and healthcare researchers. objective(s): this literature review examined outcome measurement tools used with non-amputee and amputee populations to assess hand activity. the objectives were to identify which characteristics of hand activity are captured by currently available measurement tools. methodology: searches were conducted using pubmed, cochrane and proquest for studies investigating hand activity for amputee and non-amputee populations. a total of 15 studies were included. prisma guidelines were used to assist with study selection. data extraction and narrative synthesis were carried out. findings: a total of 32 outcome measures were found. frequently used tools were: box and block test, swedish disabilities of the arm shoulder and hand questionnaire, and range of motion. studies employed a combination of 2 to 12 tools. themes extracted were: importance of function and quality of life, the need for realistic tasks, and the need for outcome measures specific of the population. conclusion: there is a gap in research surrounding outcome measurement tools used to assess hand activity in the amputee population. a combination of outcome measures are required to obtain insight into the hand activities of intact and amputee populations. function and quality of life are important aspects to consider when describing hand activity. article info received: july 22, 2022 accepted: december 12, 2022 published: december 25, 2022 citation carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.3 9023 keywords outcome measures, healthcare, amputee, upper limb, amputation, rehabilitation, prosthetics * corresponding author: kirsty carlyle, meng department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, united kingdom. email: kirsty.carlyle@strath.ac.uk orcid id: https://orcid.org/0000-0002-0291-4717 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 5, issue 2, article no.4. 2022 https://doi.org/10.33137/cpoj.v5i2.39023 https://doi.org/10.33137/cpoj.v5i2.39023 https://doi.org/10.33137/cpoj.v5i2.39023 mailto:kirsty.carlyle@strath.ac.uk https://orcid.org/0000-0002-0291-4717 https://jps.library.utoronto.ca/index.php/cpoj/index 2 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 canadian prosthetics & orthotics journal issn: 2561-987x outcome measures used to assess hand activity carlyle and day, 2022 desired potential as users find them difficult to control and not fully functional.6 despite advancements in prosthetic technology, people with amputations have significantly high rates of device rejection compared to other levels of prosthetic use.7 there are a range of devices and options available to people with amputation and their clinicians, however, more knowledge with respect to prosthetic performance may allow better prescription and design of prosthetics. recording patient and user outcomes is a recognised means of driving further research and development of technology.8 outcome measurement tools have been used widely in research to assess limb activity. such tools include quantitative functional tests and qualitative questionnaires. for health practitioners, standardised outcome measurement tools may allow them to better prescribe treatments for their patients. this review contributes to healthcare research by reviewing the current state-of-the-art outcome measures used to assess hand activities. the review has an overarching aim of providing a basis for further research into outcome measurement tools for assessing real world use of upper limb prosthetics. the specific aim is to examine outcome measurement tools used to assess hand activities as no such review exists in the literature. the review achieves this by meeting the following objectives: • evaluating the range of existing outcome measurement tools for intact and amputee populations when assessing hand activity • examining and comparing various outcome measurement tools used for hand activities. methodology reporting findings in a non-biased, usable format aids in advancing research and informing clinical decision making in the field of prosthetics and orthotics, and related fields. since qualitative and quantitative tools are used to report outcome measures related to hand activity, a literature review was selected as a strong approach to synthesise such data and put it into context.9 due to the different natures of the outcome measures expected to be found in the review, a narrative synthesis was performed to summarise data.10 the literature review was conducted in accordance with prisma guidelines11 as shown in figure 1. searches were run in pubmed, cochrane, proquest databases. relevant keywords used in the search were ("outcome measures" or "outcome measurement tool" or "outcome measurement tools" or "outcome measurement") and ("hand activity" or "hand activities" or "hand function") and (function* or "quality of life" or satisfaction) and (amputee or intact or amputation) not (foot or feet or lower limb). results were filtered to meet the following inclusion criteria: written in english, including adult human participants, published between august 2009 and august 2021. duplicates were removed. study titles were screened and excluded if they reported on children, measurement tools that focus on arm movement (not hands), interventions not specific to population, feasibility studies and participants with neurological conditions without involvement of healthy controls. the following types of study were excluded: systematic reviews, pilot studies, protocol developments, narrative reviews, feasibility studies and non-peer reviewed articles. systematic reviews were excluded so the study only considered original research. studies were included if they reported outcome measures and tools to assess adult human hand function and quality of life of unilateral upper limb amputees, bilateral upper limb amputees and the intact population. abstracts were screened from studies which passed or remained unclear following title screening. full texts were obtained from studies which passed or remained unclear following screening. full text screening was then conducted. the final studies were assessed for quality using a method derived from the casp checklists.12 this method involved applying a set of questions to each study which took into account the validity of results, risk of bias, quality of data, ethical considerations and the applicability of results in the context of the research question and study population (table 1). figure 1: study selection flowchart. records identified from databases (n = 761) records removed before screening: records marked as ineligible by automation tools (n = 382) records screened (n = 379) records excluded (n = 330) full-text articles assessed for eligibility (n = 49) reports excluded: wrong population (n = 20) wrong study focus (n = 6) live trial with no results published (n = 3) wrong study type (n = 3) wrong intervention (n = 1) limited data (n = 1) studies included in this review (n = 15) identification of studies via databases and registers id e n ti fi c a ti o n s c re e n in g in c lu d e d https://doi.org/10.33137/cpoj.v5i2.39023 3 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 canadian prosthetics & orthotics journal issn: 2561-987x outcome measures used to assess hand activity carlyle and day, 2022 ethical approval was not required to complete this review as no subject participation or handling of sensitive information were carried out. ethics surrounding the studies included in this review were considered. all studies involving subjects and confidential information were checked to ensure quality data was collected with appropriate ethical approval. data analysis all outcome measures used in each study were recorded and the frequency of use of each outcome measure was noted. modified or adapted versions of tools such as the original dash and quickdash – were grouped together. measures which were similar in nature through describing the same variables were grouped together. strength variables such as grip strength and precision force were grouped together to represent force control (fc). joint angle measures were grouped together (rom). shape texture identification test and self-rating of tactile gnosis were grouped together (tactile gnosis/tg). upper extremity functional scale and patient specific functional scales were grouped together (functional scales/fs). duration of hand movements and task movement times were grouped together (temporal measures/tm). outcome measures were also grouped into the following types: ‘functional’, ‘quality of life (qol)’ and ‘functional and qol’ measures. narrative synthesis was carried out with the aid of thematic analysis to determine themes. results following searching and screening, 15 studies were reviewed (table 2). a data extraction table (table 3) was used to record number of outcome measures, types of outcome measures, participant demographics and ethical considerations. table 1: quality appraisal checklist. author (year) s o b u h e t a l. , (2 0 1 4 )1 3 l a w re n c e e t a l. , (2 0 1 5 )1 4 r e s n ik a n d b o rg ia ( 2 0 1 6 )1 5 r a v e h e t a l. , (2 0 1 8 )1 6 l e e e t a l. , (2 0 2 0 )1 7 e k lu n d e t a l. , (2 0 0 9 )1 8 h ru b y e t a l. , (2 0 1 9 )1 9 r e s n ik e t a l. , (2 0 2 0 )2 0 r e s n ik e t a l. , (2 0 2 0 )2 1 s p e th e t a l. , (2 0 2 0 )2 2 w a n g e t a l. , (2 0 2 1 )2 3 h ru b y e t a l. , (2 0 1 7 )2 4 d e b o e r e t a l. , (2 0 1 6 )2 5 b o u m a e t a l. , (2 0 1 8 )2 6 b e rn a rd o n e t a l. , (2 0 1 5 )2 7 did the study address a clearly focused research question? y y y y y y y y y y y y y y y was the recruitment strategy appropriate to the aims? y y y y y y y y y y y y y y y are there any conflicts of interest? n n n n n n n y (declared financial grant) n y (declared financial grant) n n n n n was there a clearly defined study protocol? y y y y y y y y y y y y y y y do the benefits of the experimental intervention outweigh the harms and costs? y y y y y y y y y y y y y y y have ethical issues been taken into consideration? y y y y y y y y y y y y y y y is there a clear statement of findings? y y y y y y y y y y y y y y y can the results be applied to the context of hand and upper limb activity? y y y y y y y y y y y y y y y does the study find anything new or useful? y y y y y y y y y y y y y y y https://doi.org/10.33137/cpoj.v5i2.39023 4 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 canadian prosthetics & orthotics journal issn: 2561-987x outcome measures used to assess hand activity carlyle and day, 2022 table 2: list of included papers authors title year sobuh et al.,13 visuomotor behaviours when using a myoelectric prosthesis 2014 lawrence et al.,14 outcome measures for hand function naturally reveal three latent domains in older adults: strength, coordinated upper extremity function, and sensorimotor processing 2015 resnik and borgia15 responsiveness of outcome measures for upper limb prosthetic rehabilitation 2016 raveh et al.,16 myoelectric prosthesis users improve performance time and accuracy using vibrotactile feedback when visual feedback is disturbed 2018 lee et al.,17 clip-on imu system for assessing age-related changes in hand functions 2020 eklund et al.,18 hand function and disability of the arm, shoulder and hand in charcot-marie-tooth disease 2009 hruby et al.,19 bionic upper limb reconstruction: a valuable alternative in global brachial plexus avulsion injuries-a case series 2019 resnik et al.,20 a national survey of prosthesis use in veterans with major upper limb amputation: comparisons by gender 2020 resnik et al.,21 function and quality of life of unilateral major upper limb amputees: effect of prosthesis use and type 2020 speth et al.,22 assessment of tree-based statistical learning to estimate optimal personalized treatment decision rules for traumatic finger amputations 2020 wang et al.,23 application of machine learning to the identification of joint degrees of freedom involved in abnormal movement during upper limb prosthesis use 2021 hruby et al.,24 algorithm for bionic hand reconstruction in patients with global brachial plexopathies 2017 de boer et al.,25 intermanual transfer effects in below-elbow myoelectric prosthesis users 2016 bouma et al.,26 musculoskeletal complaints in individuals with finger or partial hand amputations in the netherlands: a cross-sectional study 2018 bernardon et al.,27 bilateral hand transplantation: functional benefits assessment in five patients with a mean follow-up of 7.6 years (range 413 years) 2015 table 3: data extraction table. authors/ year title ethical concerns? type of study participant demographics number of participants intact, amputee, prosthesis user or combination setting self-reported, clinician observed or combination? sobuh et al., 2014 13 visuomotor behaviours when using a myoelectric prosthesis no quantitative intact adults and adult myoelectric prosthesis users 11 combination (intact and prosthesis user) university clinician observed lawrence et al., 2015 14 outcome measures for hand function naturally reveal three latent domains in older adults: strength, coordinated upper extremity function, and sensorimotor processing no quantitative healthy older adults and older adults with osteoarthritis of the cmc joint 99 intact university/rehab centre clinician observed resnik and borgia, 2016 15 responsiveness of outcome measures for upper limb prosthetic rehabilitation no quasiexperiment al study adult upper limb amputees 39 amputee veterans affairs sites combination raveh et al., 2018 16 myoelectric prosthesis users improve performance time and accuracy using vibrotactile feedback when visual feedback is disturbed no quantitative transradial amputees using a myoelectric prosthesis with normal or corrected eyesight 12 prosthesis user laboratory combination https://doi.org/10.33137/cpoj.v5i2.39023 5 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 canadian prosthetics & orthotics journal issn: 2561-987x outcome measures used to assess hand activity carlyle and day, 2022 table 3: data extraction table (continued) authors/ year title ethical concerns? type of study participant demographics number of participants intact, amputee, prosthesis user or combination setting self-reported, clinician observed or combination? lee et al., 2020 17 clip-on imu system for assessing agerelated changes in hand functions no quantitative healthy adults (aged 20-31 and 75-89) 34 intact university clinician observed eklund et al., 2009 18 hand function and disability of the arm, shoulder and hand in charcotmarie-tooth disease no quantitative adults with charcot marie tooth and healthy controls 60 intact hospitals/clinics combination hruby et al., 2019 19 bionic upper limb reconstruction: a valuable alternative in global brachial plexus avulsion injuries-a case series no quantitative adults with complete bracial plexus injury who underwent bionic reconstruction after high level upper limb amputation 5 prosthesis user university combination resnik et al., 2020 20 a national survey of prosthesis use in veterans with major upper limb amputation: comparisons by gender no crosssectional survey adult veterans with upper limb amputation who had been treated between 2010 and 2015 808 amputee telephone survey self-reported resnik et al., 2020 21 function and quality of life of unilateral major upper limb amputees: effect of prosthesis use and type no crosssectional survey adult veterans with unilateral upper limb amputation who had been treated between 2010 and 2015 755 amputee telephone survey self-reported speth et al., 2020 22 assessment of tree-based statistical learning to estimate optimal personalized treatment decision rules for traumatic finger amputations no cohort study adult patients who underwent revision amputation or replantation 185 amputee various research centres combination wang et al., 2021 23 application of machine learning to the identification of joint degrees of freedom involved in abnormal movement during upper limb prosthesis use no quantitative adults with no upper limb disability, trained on deka bypass or body powered bypass 24 intact laboratory clinician observed hruby et al., 2017 24 algorithm for bionic hand reconstruction in patients with global brachial plexopathies no quantitative adults with posttraumatic global brachial plexopathies 5 prosthesis user university combination https://doi.org/10.33137/cpoj.v5i2.39023 6 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 canadian prosthetics & orthotics journal issn: 2561-987x outcome measures used to assess hand activity carlyle and day, 2022 studies were published between the years 2009 and 2021. across the studies, participants were categorised in the following populations: able bodied, able bodied using upper limb bypass equipment, upper limb prosthesis users; people with osteoarthritis, charcot-marie-tooth disease, upper limb/finger/hand amputation and recipients of hand and forearm allotransplantation. studies were conducted using intact only, intact and amputee/prosthesis user, and amputee/prosthesis user only populations. studies involving participants with osteoarthritis and charcot-marietooth used healthy controls, enabling their inclusion within the review. a total of 32 outcome measures were identified within the studies reviewed (table 4). the most frequently used tools and measures, as shown in figure 2, were the bbt (7), dash (7), rom (7) and fc (6). all studies used a combination of measures, ranging from 2 to 12 outcome measures assessed per study. the majority (59%) of outcome measures listed in table 4 are functional based measures. while function-based outcome measures were more prevalent within studies, some outcome measurement tools (19%) assess both function and quality of life (figure 3). the following quotes of relevance to the research topic were extracted from included studies: • "the most objective of the commonly used upper limb evaluation tools are based on time to perform a structured set of tasks, but use of these in isolation gives limited insight into ease of use of a prosthesis"13 • "the central question here is, what should we use to quantify hand function considering that we have so many choices of assessment tools and even more outcome measures stemming from these tools?"14 • "leaders in upper limb prosthetic rehabilitation understand the importance of choosing outcome measures that have been evaluated for persons with upper limb amputation and that are reliable, valid, and responsive to change"18 • “another important aspect in prosthetic rehabilitation research is the use of valid outcome measures"19 the following themes were derived from the papers in relation to assessing hand activity: the importance of function and quality of life, the need for realistic tasks, and the need for outcome measures specific to the population. discussion a the review depicts a range of outcome measures used to measure hand activity in amputee and intact populations. there was a clear indication that use of multiple outcome measures is optimum to evaluate hand activity. it could be true that it is difficult to select one tool due to lack of tools which bring together various aspects of hand activity such as function, pain, and satisfaction. table 3: data extraction table (continued) authors/ year title ethical concerns? type of study participant demographics number of participants intact, amputee, prosthesis user or combination setting self-reported, clinician observed or combination? de boer et al., 2016 25 intermanual transfer effects in below-elbow myoelectric prosthesis users no casecontrol study myoelectric prosthesis users and controls 44 combination (intact and prosthesis user) university/rehab centre clinician observed bouma et al., 2018 26 musculoskeletal complaints in individuals with finger or partial hand amputations in the netherlands: a crosssectional study no crosssectional study adult finger and hand amputees and healthy controls 201 combination (intact and amputee) questionnaire sent to participants self reported bernardon et al., 2015 27 bilateral hand transplantation: functional benefits assessment in five patients with a mean follow-up of 7.6 years no quantitative adults who underwent hand and forearm allotransplantation following trauma 5 intact (post transplantation) rehabilitation clinic combination https://doi.org/10.33137/cpoj.v5i2.39023 7 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 canadian prosthetics & orthotics journal issn: 2561-987x outcome measures used to assess hand activity carlyle and day, 2022 table 4: list of outcome measures, acronyms, type and description of measures. outcome measure acronym type description box and block test28 bbt functional test of manual dexterity swedish disabilities of the arm shoulder and hand questionnaire29 dash functional & qol self-reported measure of disability and symptoms in relation to the upper limb range of motion rom functional measure of level of movement achieved force control fc functional measure of strength achieved southampton hand assessment procedure30 shap functional test of hand function using abstract objects and adl orthotics and prosthetics user's survey31 opus functional & qol self-reported survey of outcomes and satisfaction with orthotic/prosthetic devices and services tactile gnosis tg functional ability to detect information through touch 9 hole peg test32 9hpt functional measure of finger dexterity 36-item short form survey33 sf-36 qol self-reported measure of quality of life temporal measures tm functional time-based activities and tasks edinburgh handedness inventory34 ehi functional assessment of hand dominance modified action research arm test35 marat functional assessment of hand function during grasp, pinch, grip and gross movements visual analogue scale36 vas qol measure of severity of symptoms trinity amputation and prosthetic experience scale37 tapes qol self-reported measure of experiences and satisfaction with regards to acquired amputation and prosthesis adjustment veterans sf-12 health survey with physical and mental components38 vr-12 functional & qol self-reported measure of health jebsen-taylor hand function tests39 jthft functional test of hand function carrying out a range of different adlbased tasks functional scales fs functional measure of function pain pain qol assessment of patient/user pain activity measure for upper limb amputation40 am-ula functional measure of upper limb activity performance michigan hand outcomes questionnaire41 mhq functional & qol self-reported measure of hand outcomes including pain, function, aesthetics, adl, work and satisfaction gaze behaviour gb functional assessing visual responses during tasks university of new brunswick skill and spontaneity tests42 unb-sst functional non-timed measure of function prevalence of musculoskeletal complaints msc qol self-reported indication of physical symptoms upper extremity work demands score uewd functional & qol measure specifically related to work tasks patient-reported work productivity pr-wp qol self-reported indication of level of ability to participate in work modified kapandji index43 mki functional measure of hand mobility carroll upper extremity function test44 ueft functional measure of functional impairment and severity purdue pegboard test45 ppt functional measure of gross upper limb movement and finger dexterity self-subjective global evaluations ssge qol self-reported measure of quality of life 400 point assessment46 400-pa functional test of function in tasks, strength, mobility and handling direct observation by therapist while performing tasks dto functional clinician-researcher observing participant without using a specific measure hand transplantation score system47 htss functional & qol measure of ability and quality of life following hand transplantation https://doi.org/10.33137/cpoj.v5i2.39023 8 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 canadian prosthetics & orthotics journal issn: 2561-987x outcome measures used to assess hand activity carlyle and day, 2022 figure 2: graph depicting number of times each outcome measure was used across the included studies. figure 3: pie chart showing that most outcome measures assess function, with a smaller proportion assessing qol. the reason behind choice of tool may be due to location of the study – for example in-clinic or telephone surveys. additionally, choice of tool may be a consequence of the fact that not all tools are validated for use in amputee populations. it is possible that researchers select tools based on personal preference rather than appropriateness. tools involving participant-reporting of data may not reflect physical performance, thus may not be sufficient. nonetheless, self-reported studies, which occur as surveys or interviews can attract larger sample sizes. no specific guidelines related to hand activities or therapy were highlighted within the included studies, emphasising the need for their development. there was a lack of diverse devices included in the studies with most studies involving prostheses featuring only myoelectric devices. finally, there is limited information on outcome measures for cosmetic devices. theme 1: the importance of function and quality of life when assessing hand activity a key theme was the value of both functional and quality of life assessments of hand activity. despite this finding, 59% of outcome measures used were functional measures and only 22% quality of life measures. by using a combination of outcome measurement tools, the researchers were frequently able to capture functional, and quality of life data. however, there is no standard combination, or designed pairing of tools to obtain all information. this highlights the need for development of guidelines that are comparative of both contexts. while functional domains and tasks were considered repeatedly throughout studies, it is evident that these variables affect quality of life. these variables can affect ability to participate in work and social environments which subsequently attributes to an improved quality of life. pain was another common theme found throughout studies. pain should be considered throughout performance of various functional tasks as such tasks may conversely impair function. presence of pain is likely to have a negative effect on quality of life. it is important to involve the participants’ self-reported outcomes of parameters such as pain to create a picture of their overall satisfaction. nonetheless, self-reported outcomes are limited due to selfreporting bias. outcome measures, which account for functional failures, may be advantageous in the amputee and prosthetic user population to account for actions such as failed prehension. this could provide key information about device performance as well as participant function. theme 2: need for realistic tasks when assessing hand activity another major theme was the importance of adl. many of the functional outcome measures were used in combination with other tools to put function into context. most of the studies investigating hand function, and the outcome measures included were structured in that the participants were given precise instructions to complete tasks. it must be noted that the ability to place pegs in a board, as required within the 9hpt and ppt, does not correlate to information about key parameters such as strength or function. similarly this process does not correlate with the skill required to carry out typical adl. likewise, the bbt was one of the most frequently used measures and is simple to set up but transferring blocks between compartments is one repetitive process which is not likely implemented in most adl. an overlooked element is participant-led activities during assessment. in prosthetic user populations, it would be pragmatic to ask the participant to complete tasks with their prosthesis on and off to account for a range of scenarios. it should not be assumed that users wear their device consistently. studies should include both unilateral and 19% 22%59% ratio of function and qol based outcome measure function+qol qol function 0 1 2 3 4 5 6 7 8 b b t d a s h r o m f c s h a p o p u s t g 9 h p t s f -3 6 t m e h i m a r a t v a s t a p e s v r -1 2 j t h f t f s p a in a m -u l a m h q g b u n b -s s t m s c u e w d p r -w p m k i u e f t p p t s s g e 4 0 0 -p a d t o h t s s n u m b e r o f s tu d ie s u s in g o u tc o m e m e a s u re outcome measure frequency of use of outcome measures https://doi.org/10.33137/cpoj.v5i2.39023 9 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 canadian prosthetics & orthotics journal issn: 2561-987x outcome measures used to assess hand activity carlyle and day, 2022 bilateral tasks to represent a wider range of real-life scenarios. in addition, most studies were carried out in research laboratories, clinics, and universities. this means the researcher has control within the study and this weakens the link between the hand activities and real-world applications. shifting from basic tasks to real world object manipulation, such as turning keys or picking up a mug, would provide an extra dimension in relating clinical studies to applications in the real world. theme 3: need for outcome measures specific to population different populations are known to have different key components of hand function, so the focus of functional assessment tools should be tailored to the prosthesis user population. it was also highlighted within the reviews that people value parameters differently, for example dexterity may be of more importance than strength. it would be advantageous to understand the parameters which are of importance to prosthesis users before using tools to assess hand activity. performance-based outcome measures used to assess hand activity often compare the performance of an amputee or prosthesis user with the intact population. this is not an optimal comparison since the populations have various levels of function and goals. low level strength is required to facilitate adl and functional tasks, so people with amputation who may have a level of strength too low to carry out such tasks may be unable to be assessed with such tools. also, there is a level of dexterity required for tools such as tactile gnosis assessments. if outcome measurement tools can only be used in populations with a baseline level of ability, then tools must be adapted or developed to involve people who do not satisfy this criterion. further, many of the tools used are temporal based and therefore do not give indications into ease of use, which is an important parameter when investigating the amputee and prosthesis user populations. another argument for using outcome measures specific to the population is that a specific measurement may alleviate the need for recruiting healthy, intact participants when researchers are interested in outcomes of amputee or prosthesis users only. limitations a limitation of this review is that data from pilot studies, reviews and protocol development studies were not included. therefore, outcome measures considered are not a comprehensive list. inclusion was limited to studies published in more recent years to ensure conclusions were reflective of the current state of technology and practice. studies which only included participants with neurological conditions were excluded to ensure the correct population was analysed. studies which used stroke-specific tools were excluded as outcome measurement tool selection by the research may be biased towards the stroke population and thus not a true reflection of amputee or intact populations. small sample sizes within many included studies are another limiting factor, as this restricts data available for assessment. studies with larger sample sizes were self-reported surveys which are limited in terms of outcome measurement tools which can be used. only one reviewer screened and selected articles for inclusion, thus presenting a potential element of bias in terms of study selection. conclusion there is a definite gap in research surrounding outcome measurement tools used to assess hand activity in the amputee and prosthesis user population. results from this review of outcome measures used in amputee and intact populations, showed that a combination of outcome measures are currently used to obtain insight into hand activities of intact and amputee populations. there are no set guidelines or recommended pairings of tools, and key information about hand activity could potentially be missed during investigations. the reason a combination of tools are used is partially because currently used outcome measurement tools are limited for use in amputee and prosthesis user populations. some measurement tools were not validated for upper limb amputees, and some involving temporal based tasks may not have been appropriate for assessing function in prosthesis users. additionally, combinations of tools are used because both function and quality of life measurements are deemed important. these aspects are of particular interest in amputee and prosthetic user populations where factors such as pain, social participation and satisfaction are of high importance to both the person themselves, healthcare practitioners and prosthesis developers. tools should be developed with both functional and quality of life measurements taken into consideration as well as tasks which pose a likeness to carrying out adl. finally, tools should be developed specific to the population to ensure that measurements are valid, useful, and specific. acknowledgements n/a declaration of conflicting interests the authors declare that there is no conflict of interest. authors contribution kirsty carlyle: designed the research question and study design, conducted the literature search and study selection, writing the manuscript. sarah day: designed the research question and study design, writing the manuscript. https://doi.org/10.33137/cpoj.v5i2.39023 10 carlyle k, day s. outcome measures used to assess hand activity in amputee and intact populations: a literature review. canadian prosthetics & orthotics journal. 2022; volume 5, issue 2, no.4. https://doi.org/10.33137/cpoj.v5i2.39023 canadian prosthetics & orthotics journal issn: 2561-987x outcome measures used to assess hand activity carlyle and day, 2022 sources of support this work was supported by the uk engineering and physical sciences research council (epsrc) grant ep/s02249x/1 for the centre for doctoral training in 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(eds) hand transplantation. springer, milano. 2007. doi: 10.1007/978-88-470-0374-3_44 https://doi.org/10.33137/cpoj.v5i2.39023 http://www.shap.ecs.soton.ac.uk/ https://www.rand.org/health-care/surveys_tools/mos/36-item-short-form.html https://www.rand.org/health-care/surveys_tools/mos/36-item-short-form.html https://www.codetechnology.com/blog/vr-12-general-health-pro-tool/ https://www.codetechnology.com/blog/vr-12-general-health-pro-tool/ https://www.unb.ca/ibme/_assets/documents/test-of-prosthetic-function.pdf https://www.unb.ca/ibme/_assets/documents/test-of-prosthetic-function.pdf https://strokengine.ca/en/assessments/upper-extremity-function-test-ueft/ https://strokengine.ca/en/assessments/upper-extremity-function-test-ueft/ all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 2 2025 research article frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i2.45790 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 research article evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study frossard l1, 2, 3, 4 *, laux s5, geada m5, tronicke l6, fridriksson t6, lechler k6 1. yourresearchproject pty ltd, brisbane, australia. 2. griffith university, southport, australia. 3. queensland university of technology, brisbane, australia. 4. university of the sunshine coast, sippy downs, australia. 5. apc prosthetics pty ltd, alexandria, australia. 6. össur, r&d, medical office, reykjavik, iceland. introduction clinical outcomes of bone-anchored prostheses a bone-anchored prosthesis (bap) connected to an osseointegrated implant might be indicated for some individuals with transfemoral amputation (tfa).1-3 in principle, daily loading regimen applied on the implant during prosthesis use may be related to at least six of the nine most common transfemoral bone-anchored prosthesis (tf-bap) adverse events (e.g., superficial and deep infections, loosening, falls, periprosthetic fractures and implant breakage; appendix-figure s1).4,5 ideally, the loads applied during rehabilitation and beyond should be within a pain-free and bespoke “goldilocks zone” where the “right load” is applied at the “right time”.6-8 in all cases, it is critical to understand how the loading profiles vary between tf-bap equipped with compatible components.9-12 understanding prosthetic loading profile approximately 65 publications referred to loading characteristics associated with lower limb baps, including * corresponding author: professor laurent frossard, (phd) affiliation: 1) yourresearchproject pty ltd, brisbane, australia; 2) griffith university, southport, australia; 3) queensland university of technology, brisbane, australia; 4) university of the sunshine coast, sippy downs, australia. e-mail: laurentfrossard@outlook.com orcid id: https://orcid.org/0000-0002-0248-9589 open access abstract background: a transfemoral bone-anchored prosthesis (tf-bap) can be fitted with non-microprocessorcontrolled knees (n-mpks), or with microprocessor-controlled knees, which can be passive (p-mpks) or active (a-mpks). the next generation of a-mpks, including powered knees, is emerging. the understanding of the loading applied on tf-bap fitted with these a-mpks is limited. objective: this cross-sectional study aimed to characterize the load applied on instrumented tf-bap fitted with an a-mpk (power knee, össur, iceland) during standardized daily activities. furthermore, some load characteristics applied during walking were compared with tf-bap fitted with n-mpk and p-mpk reported in the literature using similar approach. methodology: thirteen males fitted with a transfemoral press-fit osseointegrated implant participated in this study between 2021 and 2022. forces and moments applied on the instrumented tf-bap, fitted with a power knee (pka01) and pro-flex (lp, xc) or balance s feet (össur, iceland), were measured wirelessly using an ipecslab (rtc electronics, usa) during walking, ascending and descending ramp and stairs. we followed a 28-step process to characterize the loading pattern considering spatiotemporal gaits variables as well as loading boundaries and extrema. findings: overall, 1,327 steps were analyzed. the cadence ranged between 34 ± 6 and 49 ± 13 strides/min. the maximum forces and moments recorded on the long, anteroposterior and mediolateral axes of the transducer were 1,258 n, 331 n and 234 n as well as 19 nm, 74 nm and 91 nm, respectively. conclusion: the power knee, combined with pro-flex or balance s feet, may improve participants’ capacity to ambulate. comparations with reference values indicated that transitions from n-mpks or p-mpks to the power knee are considered safe and likely to improve efficiency. this study contributed to evidencebased recommendations of tf-bap fitted with powered knees. hopefully, this work will advance clinical practice guidelines for the growing population choosing bionic solutions. article info received: july 31, 2025 accepted: october 25, 2025 published: november 2, 2025 citation frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral boneanchored prostheses: a crosssectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v 8i2.45790 keywords amputation; artificial limbs; bionics; kinetics; loading; bone-anchored prosthesis; lower limb; prosthesis; osseointegrated implant; microprocessor-controlled knees. journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 2, article no. 4. 2025 https://doi.org/10.33137/cpoj.v8i2.45790 mailto:laurentfrossard@outlook.com https://orcid.org/0000-0002-0248-9589 https://doi.org/10.33137/cpoj.v8i2.45790 https://doi.org/10.33137/cpoj.v8i2.45790 https://jps.library.utoronto.ca/index.php/cpoj/index 2 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 landmark reviews presented by niswander et al (2020) and ravari et al (2024).13,14 these reviews indicated that portable kinetic systems including tri-axial transducers embedded into a lower limb baps have been used to measure directly the load profile applied on osseointegrated implants during standardized rehabilitation and daily activities.6,10,11,15-24 cross-sectional cohort studies have previously looked at instrumented tf-bap fitted with components recommended as best-practice at the time, such as total knee 1900, c-leg and rheo knee xc.6,15,16,22-24 in our previous study, 10 tfas were fitted mainly with basic prosthetic knees components such as mechanically passive knees or non-microprocessor-controlled knee (n-mpks), the first passive microprocessor-controlled knee (p-mpk) and various prosthetic feet component.15,16,25 more recently, in our study, 13 tfas were fitted with the rheo knee xc (össur) and energy-storing-and-returning feet (esars).6,26 as presented in frossard et al,25,26 the maximum force and moment expressed as a percentage of body weight (%bw) were 84 ± 7 %bw and 2.63 ± 1.04 %bw·m while walking with a tf-bap fitted with the gaitmaster, total knee 1900, adaptive, or c-leg, and 102 ± 7 %bw and 3.44 ± 0.98 %bw·m while walking with the rheo knee xc. over time, the repetition of such studies has led to a more standardized ecological approach to characterize loading profiles. the strength of this ecological approach is to report everyday loading regimen but its limitation is to overlook informative 3d dynamic, kinematic and inverse dynamic data.17,21,27-32 need for characterization of loading profile with the power knee nowadays, the prescription of recent p-mpks and esars components is commonly recognized as the cost-effective standard of care when fitting tf-bap.1,6,13,14,33-37 the next generation of active microprocessor-controlled knees (a-mpks), including powered knees, is emerging.38-40 a-mpks use motors to actively assist with activities such as walking, standing up and climbing stairs. the development of active prostheses is the subject of many research projects with the vision of making walking with a prosthesis more natural and efficient for the user through adaptive actuators.39-42 the power knee (össur, iceland) is the first commercially available motor-powered a-mpk. it actively supports flexion and extension adapted to the user´s activity.43 furthermore, it can improve the loading symmetry between sound and prosthetic sides during walking and sitto-stand movements and supports the user during stepover-step stair ascent.44 to the best of our knowledge, there are limited studies on the loading profile associated with tf-bap fitted with the power knee.36 therefore, there is a need for studies characterizing the loading profile using an ecological approach to facilitate comparisons with previous studies that focused on other recommended components for tf-bap. purposes the purpose of this cross-sectional study was to characterize the loading profile applied on tf-bap when fitted with the power knee using an ecological approach (e.g., direct measurement of the load in quasi real-world conditions). the specific objectives were to: 1. present the range and variability of spatiotemporal gait variables, the magnitude of loading boundaries, as well as the onset and magnitude of extrema applied to the instrumented tf-bap fitted with a power knee, pro-flex (lp or xc), or balance s feet during standardized straightlevel walking and while ascending and descending ramps and stairs, 2. compare some of these loading characteristics with those reported in the literature for tf-baps fitted with nmpks and a recent p-mpk (rheo knee xc).6,15,16,20,25,26 methodology design this cross-sectional interventional study was a part of a registered clinical trial (clinicaltrials.gov: 2021-yrp-llaload-01). populations individuals fitted with tf-bap were recruited by a prosthetist using established selection criteria presented in appendix-table s1.6,15,16,20,26,45 there was no specific exclusion criteria related to gender, ethnicity, height or functional level. all participants were fitted with a non-fda approved press-fit implant, (i.e., osseointegration prosthetic limb, permedica spa, italy). assessment took place in sydney, australia between december 2021 and june 2022. participants signed a written ethical consent form (protocol no: bellberry hrec-2021-yrp-lla-load01). extraction load profile was extracted following a standardized 28-step process outlined in table 1 that emerged from previous studies.6,10,11,15,16,18,20,22,26 key steps of the process are detailed below. recording the loading was recorded during step 1-18 (table 1-a). the instrumented prostheses included ipecslab’s transducer (rtc electronics, usa) fitted between the connector and a power knee (n = 13, 100%) so that loading could be measured directly (appendix-figure s2). the participants were fitted with pro-flex lp (n = 7, 53%), pro-flex xc (n = 4, 30%) or balance s (n = 2, 15%) prosthetic feet and their https://doi.org/10.33137/cpoj.v8i2.45790 3 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 own footwear. we purposely chose the lp and xc models within the pro-flex ankles family which are commonly recommended for patients in australia based on their ability to tolerate high impacts. each force (f) and moment (m) were measured wirelessly at 200 hz and expressed in the transducer’s coordinate system (appendix-figure s2). it was aligned so that its axes corresponded as closely as possible to the anatomical long (lg), anteroposterior (ap) and mediolateral (ml) axes of the implant (appendix-figure s3). a prosthetist performed a standard static alignment guided by principles outlined in the literature.46 in all instances, the co-linearity of the long axes of the implant and the transducer depended on the offset of the connector used to achieve the desired alignment (appendix-table s2, figure s4, figure s5). the prosthetist also performed a dynamic alignment and adjusted the knee settings that suited participants’ preferences and comfort. the loading was measured while participants performed successively up to five trials of straight level walking, ascending and descending ramp and stairs (appendix-table s3). participants were used to walk with a p-mpk such as c-leg or genium (ottobock, usa) or rheo knee xc (össur, iceland) or the power knee. regardless, they were trained on how to use the power knee functions prior each activity (e.g., step-over-step technique to ascend and descend stairs). approximately 30-60 minutes of acclimation with the prosthesis were initially deemed sufficient to achieve the required confidence and warrant safety based on literature.47 participants were instructed to perform each activity at a self-selected pace and to use the handrail if needed. processing the loading was processed during step 19-23 (table 1-b) using customized matlab software program (the mathworks inc., usa)6,15,16,20,25,26 this program enabled the identification of gait events as well as time normalization over the percentage of a gait cycle (gc) or support phase (sup) and normalization of loading datasets by percentage of bodyweight (%bw, %bwm). analysis the loading was analyzed during step 24-28 (table 1-c), also using matlab software program. the loading profile was characterized using spatiotemporal variables, loading boundaries, and up to 10 loading extrema depending on the activities. for this study, we purposely characterized the loading during critical phases of gc (table 1-step 28), including: • weight acceptance using six extrema occurring during initial phasis of the gc where the bodyweight must be applied onto the knee smoothly for comfort and safely to action stance control features, • propelling loading using four extrema occurring during the final phasis of the gc where the knee should assist shifting the center of mass slightly sideway and more importantly forward onto the sound limb. statistics the mean and standard deviation of spatiotemporal variables, loading boundaries and extrema were calculated after collating all gcs recorded for each activity. the variability of the dataset was determined using the percentage of variation (pv), calculated as: 𝑃𝑉 = | 𝑆𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝐷𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛 𝑀𝑒𝑎𝑛 × 100| to be consistent with the literature reporting interand intrasubject variability of loading data, we considered a pv below 20% to indicate low variability and a pv above 20% to indicate high variability, respectively.6,15,16,20,22,25,26 comparisons selected indicators of the loading profile were benchmarked against reference datasets extracted from the literature including able-bodied participants as well as tfas fitted with socket prostheses, n-mpks (n = 8) and p-mpks (n = 13).6,15,16,20,25,26 we only considered previous studies that used a similar protocol to reduce the confounding effects of the measurements (e.g., selection criteria, direct load measurement, loading characterization). differences between discrete indicators including spatiotemporal gait variables as well as loading boundaries and extrema were determined so that a positive difference indicated that the power knee was algebraically larger than the reference datasets. the relative difference between indicators was also expressed as a percentage of the power knee: 𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝐷𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒 (%) = 𝑃𝑜𝑤𝑒𝑟 𝐾𝑛𝑒𝑒 𝐷𝑎𝑡𝑎 − 𝑅𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝐷𝑎𝑡𝑎 𝑃𝑜𝑤𝑒𝑟 𝐾𝑛𝑒𝑒 𝐷𝑎𝑡𝑎 × 100 we considered that an absolute relative difference superior to 10% was above a minimal clinically important difference (mcid). this threshold might appear low compared to other studies considering an mcid of 20% when comparing prosthetic knee components.50 conservatively, we believe that a lower mcid was justified in the particular case of individuals fitted with tf-bap given that their proprioception is increased due to osseoperception provided by the implant.6,51 https://doi.org/10.33137/cpoj.v8i2.45790 4 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 table 1: overview of the standard ecological approach relying on 28-step process to record, extract and analyze to load profile applied on bone-anchored prosthesis emerging from the literature. f: force; m: moment; lg: long axis; ap: anteroposterior axis; ml: mediolateral axis; gc: gait cycle; %gc: percentage of gait cycle; sup: support phase; %sup: percentage of support phase; %bw: percentage of bodyweight; %bwm: percentage of bodyweight per meter; flg1: first point of interest of the force applied on the long axis; fap1: first point of interest of the force applied on the anteroposterior axis; fml1: first point of interest of the force applied on the mediolateral axis; mlg1: first point of interest of the moment applied around on the long axis; map1: first point of interest of the moment applied around the anteroposterior axis; mml1: first point of interest of the moment applied around the mediolateral axis; fap2: second point of interest of the force applied on the anteroposterior axis; mlg2: second point of interest of the moment applied around on the long axis; mml2: second point of interest of the moment applied around the mediolateral axis; mml3: third point of interest of the moment applied around mediolateral axis. step description a-recording a.1-equipment a.1.1-portable kinetic system (ipecslab, rtc electronics, usa) 1 setup sampling recording of forces and moments at 200 hz 2 setup connection so that loading data are sent wirelessly to laptop nearby 3 ensure that the forces and moments were measured with an accuracy of ±0.01 n and ±0.001 nm, respectively 4 fit transducer of the ipecslab to the instrumented prosthesis 5 align the coordinate system of the transducer that its vertical axis was co-axial with the long (lg) axis of the implant and the other axes corresponded to the anatomical anteroposterior (ap) and mediolateral (ml) directions of the implant 6 denote forces acting on the three axes of the transducer as flg, fap and fml where compression, anterior and lateral forces were positive, respectively 7 denote moments around the three axes of the transducer as mlg, map and mml where external, lateral and anterior moments were positive, respectively 8 a prosthetist performed a standard static alignment of the prosthesis guided by principles outlined in the literature 9 perform dynamic alignment and resistance adjustment for knee and foot that suited participants’ preferences and comfort 10 consider that the medullar and percutaneous parts of the implant as well as the tube and/or adaptor were one rigid part 11 measure the offset of the distal end of connector attached to the percutaneous part and the centre of the power knee in relation to the origin of coordinate system of ipecslab’s transducer 12 calibrate the transducer at the end of the recording session when the prosthesis was removed using post recording bench top measurements (i.e., zero-offset) a.1.2-video recording 13 setup basic video recording using digital camera of each trial of daily activities to facilitate the analyzes and interpretation of the loading data (e.g., digital notebook) a.2-activities 14 measure characteristics of physical setup used to perform straight level walking as well as ascending and descending ramp and stairs 15 train participant on how to use the power knee functions prior each of the ascending and descending ramp and stairs activities 16 ask participants to perform up to five trials in each activity consecutively at a self-selected comfortable pace and to use the handrail, if needed 17 advise participants to use the step-over-step (e.g., normal reciprocal stepping pattern) rather that step-by-step (e.g., placement of both feet on the same step before the next step) technique while ascending and descending stairs, when possible 18 acclimate and practice with instrumented prosthesis for 30-60 minutes prior each activity b-processing 19 calibrate the raw forces and moments for each trial by considering the magnitude of the load recorded during calibration 20 detect of relevant segment of loading data by discarding the first and the last two to three strides recorded for each trial so that the steps analyzed where at a steady pace, outside of gait initiation and termination, respectively 21 determine of gait events using the plot of flg to detect manually individual heel contacts and toe-offs events within the relevant segment for each trial 22 normalize datasets by the time from 0 to 100 throughout the gait cycle (gc) or support phases (sup) to facilitate averaging of trials as well as reporting of spatiotemporal characteristic and extrema in percentage of gait cycle (%gc) or support (%sup), respectively 23 normalize forces and moments datasets by percentage of bodyweight (%bw, %bwm) c-analysis 24 extract three spatiotemporal variables including the cadence in strides per minute (stride/min) for a given trial (i.e., duration between two consecutive heel contacts of the prosthetic limb so that cadence of prosthetic limb did not always equate to the number of steps ascended or descended during stairs activities depending on step-over-step or step-by-step technique), duration of gait cycle in seconds (s), and duration of the support phases in percentage of gait cycle (%gc) 25 extract 12 loading boundaries across all gait cycles per activity regardless of the onset including the minimum, maximum, and maximum of the absolute minimum and maximum magnitude of forces in n and %bw and moments in nm and %bwm 26 extract 36 overall loading boundaries across all activities including the minimum, maximum, and maximum of the absolute minimum and maximum magnitude of forces in n and %bw and moments in nm and %bwm 27 extract semi-automatically (e.g., searching the minimum or maximum magnitude of forces and moment within a pre-set time window) up to 10 loading extrema (i.e., points of inflection of the loading pattern occurring consistently over successive steps for a given activity for all participants per activity including onset in %sup (i.e., time of occurrence of extremum) and magnitude in n and %bw or nm and %bwm (i.e., minimum or maximum magnitude of point on the curve of forces and moment within a pre-set time window) 28 characterize weight acceptance and propelling loading considering six (i.e., flg1, fap1, fml1, mlg1, map1, mml1) and four (i.e., fap2, mlg2, mml2, mml3) loading extrema occurring during the critical initial and final phases of the gait cycle, respectively https://doi.org/10.33137/cpoj.v8i2.45790 5 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 results a cohort of 13 males with tfas participated in this study (64 ± 13 years; 1.79 ± 0.06 m; 93.7 ± 15.5 kg; 27.6 ± 4.2 kg/m2), as detailed in table 2. participation of only males was unintended and accidental. the surgical timeline was 11 ± 9 years since amputation and 6 ± 3 years since implantation. the residuum length was 33.6 ± 4.9 cm or 71 ± 10 % of sound thigh. a total of 1,327 gcs was analyzed including 538 for walking, 230 for ascending ramps, 265 for descending ramp, 137 for ascending stairs and 157 for descending stairs activities (appendix-table s4). only 7 (54%) participants could perform stairs activities using “step-overstep technique (e.g., two-stairs at the time) and “foot on the edge of the step” techniques. spatiotemporal gait variables as detailed in table 3-a, 10 (67%) spatiotemporal variables showed a low variability across all activities. however, high variability was noticeable for five (33%) variables including the cadence during walking and descending ramp as well as the duration of the gc during walking, descending a ramp and ascending stairs. the percutaneous part was 0.8 ± 1.7 cm, -0.1 ± 0.6 cm and 9.6 ± 1.5 cm while the geometrical center of the power knee was 0.1 ±1.3 cm, -0.2 ± 0.9 cm and -8.4 ± 0.6 cm away from the center of the transducer on the ap, ml and lg axes, respectively (appendix-figure s3, table s2, figure s4, figure s5). the mean and standard deviation of the loading pattern applied on the transducer over the support phase during walking, ascending and descending ramp and stairs are presented in figure 1, figure 2 and figure 3, respectively. loading boundaries as presented in table 3-b, 54 (90%) out of the 60 loading boundaries showed high variability. the variability was low for the average minimum load on mml during ascending stairs and the average maximum loads on flg in all activities. the loading ranged between: • -305 n or -32 %bw and 1,258 n or 147 %bw on flg, • -331 n or -47 %bw and 224 n or 25 %bw on fap, • -47 n or -6 %bw and 234 n or 21 %bw on fml, • 17 nm or -2.2 %bwm and 19 nm or 2.0 %bwm on mlg, • -74 nm or -6.6 %bwm and 20 nm or 1.9 %bwm on map, • -82 nm or -8.7 %bwm and 91 nm or 9.7 %bwm on mml. the positive and negative values depended on the orientation of the transducer coordinate system, as presented in table 1-steps 6 and 7. table 2: overall and individual demographics, amputation, and prosthetic information of participants fitted with the instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s). bmi: body mass index; tr: trauma; tu: tumor; l: left; r: right; amp: amputation; tf-bap: transfemoral bone-anchored prosthesis; %snd: percentage of sound thigh length. no. demographics amputation length of residuum prosthesis age height mass1 bmi2 cause side time since amp time since tfbap foot footwear (yrs) (m) (kg) (kg/m2) (l/r) (yrs) (yrs) (cm) (%snd) 1 60 1.77 83 25 tr r 1.94 1.91 38 87 pro-flex lp running shoes 2 62 1.78 62 18 tu r 4.11 3.88 22 50 pro-flex lp running shoes 3 66 1.83 108 31 tr r 30.63 9.70 34 77 pro-flex lp running shoes 4 59 1.78 95 28 tr r 5.43 4.03 38 77 pro-flex lp dressing shoes 5 64 1.70 96 33 tr r 21.06 12.30 28 70 pro-flex lp running shoes 6 85 1.83 115 33 tr r 18.73 5.19 32 71 pro-flex lp flat shoes 7 56 1.83 95 27 tr r 3.08 3.06 41 82 pro-flex lp runners 8 63 1.85 114 32 tr l 5.93 5.64 38 79 pro-flex xc city shoes 9 35 1.87 108 29 tr l 12.39 10.64 32 64 pro-flex xc runners 10 62 1.83 86 24 tr l 9.44 5.23 33 62 pro-flex xc flat shoes 11 81 1.67 73 25 tr r 7.02 3.89 35 70 pro-flex xc runners 12 59 1.86 97 27 tu l 20.15 9.31 34 64 balance s running shoe 13 76 1.73 86 27 tr l 2.46 2.46 32 68 balance s trekking shoes mean 64 1.79 93.6 27.6 10.95 5.94 33.6 71.0 sd 13 0.06 15.5 4.2 9.00 3.39 4.9 9.8 1 body mass without prosthesis; 2 calculated based on body mass without prosthesis. https://doi.org/10.33137/cpoj.v8i2.45790 6 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 figure 1: average and standard deviation (thin lines) of loading profile applied on instrumented prosthesis with the power knee during walking (13 participants, 538 gait cycles). %bw: percentage of the bodyweight; %sup: percentage of the support phase. https://doi.org/10.33137/cpoj.v8i2.45790 7 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 figure 2: average and standard deviation (thin lines) of loading profile applied on the instrumented prosthesis with the power knee during ascending (12 participants, 230 gait cycles) and descending (12 participants, 265 gait cycles) ramp. %bw: percentage of the bodyweight; %sup: percentage of the support phase. https://doi.org/10.33137/cpoj.v8i2.45790 8 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 figure 3: average and standard deviation (thin lines) of loading profile applied on the instrumented prosthesis with the power knee during ascending (7 participants, 137 gait cycles) and descending (7 participants, 157 gait cycles) stairs. %bw: percentage of the bodyweight; %sup: percentage of the support phase. https://doi.org/10.33137/cpoj.v8i2.45790 9 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 table 3: mean and standard deviation as well as variability of spatiotemporal variables, loading boundaries and loading extrema applied on the instrumented prosthesis with the power knee. sd: standard deviation; s: second; %gc: percentage of gait cycle; f: force; m: moment; lg: long axis; ap: anteroposterior axis; ml: mediolateral axis; %bw: percentage of the bodyweight; %sup: percentage of the support phase; h: high percentage of variation; l: low percentage of variation; flg1: first point of interest of the force applied on the long axis; fap1: first point of interest of the force applied on the anteroposterior axis; fml1: first point of interest of the force applied on the mediolateral axis; mlg1: first point of interest of the moment applied around on the long axis; map1: first point of interest of the moment applied around the anteroposterior axis; mml1: first point of interest of the moment applied around the mediolateral axis; fap2: second point of interest of the force applied on the anteroposterior axis; mlg2: second point of interest of the moment applied around on the long axis; mml2: second point of interest of the moment applied around the mediolateral axis; mml3: third point of interest of the moment applied around mediolateral axis. walking ascending ramp descending ramp ascending stairs descending stairs a-spatiotemporal variables cadence (strides/min) 49 ± 13 h 46 ± 8 l 43 ± 10 h 34 ± 6 l 45 ± 6 l gait cycle (s) 1.3 ± 0.3 h 1.3 ± 0.2 l 1.5 ± 0.4 h 1.9 ± 0.4 h 1.4 ± 0.2 l support (%gc) 63 ± 5 l 63 ± 4 l 62 ± 7 l 58 ± 6 l 52 ± 6 l b-loading boundaries minimum flg (%bw) -0.9 ± 2.0 h -0.5 ± 0.7 h -0.4 ± 0.9 h -4.4 ± 3.5 h -2.7 ± 6.8 h fap (%bw) -10.1 ± 3.8 h -8.8 ± 3.4 h -14.8 ± 6.2 h -19.9 ± 6.4 h -28.2 ± 7.4 h fml (%bw) -1.1 ± 1.1 h -1.1 ± 1.4 h -0.7 ± 0.6 h -0.4 ± 0.6 h -1.1 ± 1.0 h mlg (%bwm) -0.53 ± 0.33 h -0.33 ± 0.26 h -0.61 ± 0.41 h -0.81 ± 0.28 h -0.95 ± 0.41 h map (%bwm) -3.61 ± 1.07 h -3.50 ± 1.04 h -3.07 ± 1.10 h -2.92 ± 0.61 h -2.34 ± 0.70 h mml (%bwm) -2.32 ± 0.70 h -2.14 ± 0.62 h -3.58 ± 1.89 h -3.20 ± 1.05 h -6.14 ± 1.06 l maximum flg (%bw) 102.4 ± 7.1 l 100.4 ± 4.1 l 99.6 ± 11.4 l 99.4 ± 5.4 l 84.1 ± 14.8 l fap (%bw) 16.4 ± 4.9 h 16.4 ± 3.3 h 8.6 ± 5.7 h 6.8 ± 4.6 h 4.3 ± 1.7 h fml (%bw) 10.1 ± 3.7 h 9.7 ± 3.6 h 8.5 ± 2.9 h 8.8 ± 3.7 h 6.3 ± 2.9 h mlg (%bwm) 0.88 ± 0.44 h 0.97 ± 0.34 h 0.34 ± 0.32 h 0.81 ± 0.36 h 0.21 ± 0.16 h map (%bwm) 0.61 ± 0.42 h 0.64 ± 0.49 h 0.37 ± 0.23 h 0.66 ± 0.41 h 0.44 ± 0.25 h mml (%bwm) 3.41 ± 1.29 h 5.11 ± 1.17 h 1.70 ± 1.28 h 6.19 ± 1.90 h 0.63 ± 0.35 h c-loading extrema onset weight acceptance flg1 (%sup) 41.8 ± 14.63 h 50.3 ± 15.8 h 38.5 ± 13.8 h 73.6 ± 17.6 h 21.8 ± 12.8 h fap1 (%sup) 16.9 ± 6.2 h 17.6 ± 6.2 h 40.5 ± 26.0 h 18.8 ± 9.9 h 56.2 ± 17.2 h fml1 (%sup) 44.2 ± 12.8 h 44.0 ± 11.9 h 45.6 ± 13.4 h 67.7 ± 20.3 h 30.9 ± 14.4 h mlg1 (%sup) 23.7 ± 11.3 h 15.7 ± 7.0 h 35.7 ± 21.4 h 19.1 ± 7.7 h 53.4 ± 17.1 h map1 (%sup) 45.0 ± 14.0 h 45.0 ± 13.6 h 47.8 ± 14.7 h 65.2 ± 25.2 h 26.3 ± 12.9 h mml1 (%sup) 13.6 ± 11.0 h 6.5 ± 5.8 h 35.0 ± 31.3 h 52.8 ± 23.3 h 67.6 ± 14.3 h propelling loads fap2 (%sup) 79.2 ± 5.1 l 79.1 ± 5.0 l 88.8 ± 9.9 l 76.6 ± 25.6 h mlg2 (%sup) 68.6 ± 11.0 l 61.8 ± 11.7 l 77.9 ± 21.8 h 69.8 ± 20.8 h mml2 (%sup) 65.2 ± 9.2 l 62.3 ± 8.9 l 83.5 ± 8.7 l mml3 (%sup) 91.8 ± 5.4 l 92.3 ± 4.9 l magnitude weight acceptance flg1 (%bw) 102.4 ± 7.1 l 100.4 ± 4.0 l 99.6 ± 11.4 l 99.4 ± 5.4 l 84.1 ± 14.8 l fap1 (%bw) -10.1 ± 3.8 h -8.8 ± 3.4 h -14.7 ± 6.1 h -19.9 ± 6.4 h -28.2 ± 7.4 h fml1 (%bw) 10.1 ± 3.7 h 9.7 ± 3.6 h 8.5 ± 2.9 h 8.8 ± 3.7 h 6.3 ± 2.9 h mlg1 (%bwm) -0.53 ± 0.34 h -0.31 ± 0.27 h -0.59 ± 0.42 h -0.81 ± 0.28 h -0.94 ± 0.41 h map1 (%bwm) -3.61 ± 1.07 h -3.50 ± 1.04 h -3.07 ± 1.10 h -2.92 ± 0.61 h -2.34 ± 0.70 h mml1 (%bwm) -0.85 ± 1.02 h -0.26 ± 0.43 h 1.70 ± 1.28 h 6.19 ± 1.90 h -6.14 ± 1.06 l propelling loads fap2 (%bw) 16.4 ± 4.9 h 16.4 ± 3.3 h 8.2 ± 6.2 h 6.6 ± 4.7 h mlg2 (%bwm) 0.88 ± 0.44 h 0.97 ± 0.34 h 0.30 ± 0.35 h 0.80 ± 0.38 h mml2 (%bwm) 3.32 ± 1.37 h 5.01 ± 1.31 h -3.48 ± 1.93 h mml3 (%bwm) -2.27 ± 0.64 h -2.14 ± 0.63 h https://doi.org/10.33137/cpoj.v8i2.45790 10 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 loading extrema as detailed in table 3-c and appendix-figure s6-figure s15, the loading profile applied during the daily activities was characterized by up to ten extrema for level walking and ascending ramp, nine for descending ramp, eight for ascending stairs and six for descending stairs including: • first point of interest of the force applied on the long axis (flg1), • first point of interest of the force applied on the anteroposterior axis (fap1), • second point of interest of the force applied on the anteroposterior axis (fap2), • first point of interest of the force applied on the mediolateral axis (fml1), • first point of interest of the moment applied around on the long axis (mlg1), • second point of interest of the moment applied around on the long axis (mlg2), • first point of interest of the moment applied around the anteroposterior axis (map1), • first point of interest of the moment applied around the mediolateral axis (mml1), • second point of interest of the moment applied around the mediolateral axis (mml2) • third point of interest of the moment applied around the mediolateral axis (mml3)6,26 altogether, the onset and magnitude of the extrema showed a high variability for 33 (77%) and 37 (86%) out of 43 extrema, respectively. the six extrema occurring during the weight acceptance phase had an onset and a magnitude with high variability, expected for the magnitude of flg1 during all activities and mml1 during descending stairs. the four extrema occurring during the propelling phase had an table 4: differences in gait and load characteristics produced with power knee compared to reference values produced with total knee and rheo knee xc during walking.6,15,16,25,26 n-mpk (a) 15,16,25 p-mpk (b) 6,26 (unit) (%) (unit) (%) a-spatiotemporal variables cadence (strides/min) 2.12 4 b 2.43 5 b duration gait cycle (s) -0.02 -1 b -0.07 -5 b duration support (%gc) 6.69 11 a -0.26 0 b b-loading boundaries (c) flg (%bw) 16.5 16 a 0.4 0 b fap (%bw) 2.5 15 a -3.4 -21 a fml (%bw) -1.0 -10 b 3.1 31 a mlg (%bwm) 0.40 45 a 0.15 17 a map (%bwm) 0.70 19 a 0.17 5 b mml (%bwm) 0.89 26 a -0.72 -21 a c-loading extrema weight acceptance flg1 (%bw) 16.5 16 a 0.4 0.4 b fap1 (%bw) -1.5 15 a 1.3 -12 a fml1 (%bw) -1.0 -10 b 3.1 31 a mlg1 (%bwm) -0.11 22 a -0.10 18 a map1 (%bwm) -0.70 19 a -0.17 5 b mml1 (%bwm) 1.00 -117 a -0.10 12 a propelling loads fap2 (%bw) 2.5 15 a -3.4 -21 a mlg2 (%bwm) 0.40 46 a 0.15 17 a mml2 (%bwm) 1.87 57 a -0.78 -23 a mml3 (%bwm) 0.17 -7 b 0.20 -9 b (a) including polycentric total knee 1900 = 6 fitted with trustep = 3, c-walk = 2 or unknown = 1 prosthetic feet components extracted from references 15, 16, and 25; (b) including rheo knee xc = 13 fitted with pro-flex lp = 7 or pro-flex xc = 4 prosthetic foot components; (c) absolute maximum magnitude. https://doi.org/10.33137/cpoj.v8i2.45790 11 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 onset with low variability, expected for fap2 during ascending stairs and mlg2 during descending ramp and ascending stairs, but a magnitude with high variability. benchmark as presented in table 4-a and appendix-table s5, the duration of the support phases was also 7 %gc, 11% longer above mcid compared to n-mpks. the differences in all the other spatiotemporal gait variables between the power knee and participants fitted with socket prostheses, nmpks and recent p-mpks were below mcid. the selfselected walking cadence with the power knee was 9 strides/min slower than able-bodied participants and 5 strides/min faster than sockets users. the duration of the support phases was also 0.19 s. as outlined in table 4-b and appendix-table s5-b, the differences between forces and moments applied by the power knee and tf-bap fitted with n-mpk during walking were ranged between -4 n or -1.00 %bw and 209 n or 16.50 %bw as well as 4.16 nm or 0.40 %bwm and 9.98 nm or 0.89 %bwm, respectively. the six differences between forces and moments applied were above mcid expected from fml. four out of six differences between forces and moments applied on the power knee and tfbap fitted with p-mpks were also above mcid ranging between -13 n or -3.38 %bw and 61 n or 3.13 %bw as well as -5 nm or -0.72 %bwm and 4 nm or 0.17 %bwm, respectively. as detailed in table 4-c and appendix-table s5-c, walking with the power knee reduced three extrema (i.e., fap1, mlg1, map1) and increased two extrema (i.e., flg1, mml1) during the weight acceptance while increasing three extrema (e.g., fap2, mlg2, mml3) during propelling loading above mcid compared to n-pmk. the power knee increased all forces extrema and reduced all moments extrema during the weight acceptance while increasing and decreasing two extrema during propelling loading compared to p-mpk. discussion this cross-sectional study characterized the loads applied to an instrumented tf-bap fitted with an a-mpk (power knee, össur, iceland) during standardized daily activities. key results this cross-sectional study showed that the load applied on tf-bap fitted with a power knee was characterized by: • a self-selected cadence ranging from 34 ± 6 to 49 ± 13 strides/min during walking, ascending and descending ramp and stairs. • absolute loading boundaries equal to 147 %bw on flg, 47 %bw on fap, 21 %bw on fml, 2.2 %bwm on mlg, 6.6 %bwm on map and 9.7 %bwm on mml. • a low variability for 10 (67%) of spatiotemporal variables but high variability for 54 (90%) loading boundaries and magnitude of 37 (86%) loading extrema. interpretation similarly to previous studies, the outcomes showed a high variability typical of symptomatic populations like tfas.6,15,16,25,26 several factors of heterogeneity might contribute to high variability such as the diversity of prosthetic feet, alignment of the prosthesis and offset of the transducer as well as short acclimation as detailed below. compared to reference values collated by frossard et al,20,25,52 the instrumented tf-bap fitted with the power knee may restore noticeably the spatiotemporal gait variables. indeed, the cadence was 11% faster above mcid than participants fitted with socket, at least when ambulating at self-selected pace. the loading boundaries were found to be within a range considered appropriate for safe coupling between healthy bone and implant. the extrema occurring during the weight acceptance and propelling loading including flg1 and fap2 were 16.50 %bw (16%) and 2.49 %bw (15%) higher and above mcid for the power knee compared to tf-bap fitted with n-mpk, respectively. further studies will be required to confirm that these increases might translate into more symmetrical loading with the sound limb.53-55 altogether, these outcomes suggest that the power knee may contribute to improve the walking ability, particularly walking pace, compared to nmpk. the outcomes of the comparison with recent studies involving the rheo knee xc and pro-flex feet might be less certain. flg1 was 0.42 %bw (0.41%) higher but below mcid with the power knee confirming its weight acceptance abilities. fap2 was 3.38 %bw (21%) less and above mcid with the power knee suggesting a relatively lower capacity to generate propelling forces. however, differences might be due to a larger proportion of participants fitted with pro-flex xc (n=9, 70%) in the p-mpk study.15,16,25 the design of the pro-flex xc allows higher ankle push-off power and range of motion compared to the pro-flex lp.56-58 further investigations are required to establish the impact of prosthetic feet varying in stiffness and range of movement on the loading profiles of tf-bap (e.g., index of anthropomorphy).12,48,59 limitations the limitations constricting clinical interpretations inherent to the study design related to: the sample size; the presentation of the load datasets in relation to the transducer rather than the implant; the offset of the https://doi.org/10.33137/cpoj.v8i2.45790 12 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 transducer attached to the connector; the dynamic alignments without standardization and stiffness of the prosthetic feet; the lack of spatial (e.g., walking base, step and stride length), dynamics (e.g., ground and handrail reaction forces), kinematics (e.g., trunk bending, hip range of movement) and kinetics (e.g., ankle, knee, and hip joint moments and work) characteristics; and, the educated choices for the pv’s and mcid’s thresholds. a specific limitation was the short acclimation with the instrumented prosthesis. we anticipated that participants will acclimate rapidly to the instrumented prosthesis given their previous experience with p-mpks or a-mpks.47 however, optimizing individual settings for each task might required more than one session with the prosthetist and a longer adaptation. so, limited adaptation time to the active support of the device especially during ramp and stair activities might have led to a more tentative and variable gait pattern and slower walking speeds (e.g., increase variability of extrema, decrease propelling loading, use of the handrail). generalization the main barrier to generalizing these outcomes was the relatively small sample size (n = 13) and the maledominated cohort. covid-19 pandemic impeded recruitment of participants and extensive testing (e.g., acclimation). however, our ecological approach allowed to capture a larger number of steps than typical studies relying on fixed-equipment.21,27-32,53,54,60-63 as mentioned above, several weeks of acclimation might decrease variability and increase the generalization of the outcomes. the generalization of the outcomes to other commercially available powered knees might be uncertain due to different specificities of their design. future studies this study can inform the design of subsequent observational studies with larger cohorts focusing on loading profile applied on tf-bap with various component configurations (esars, p-mpks, a-mpks).55,64-67 practically, the range of loading characteristics presented here can facilitate the calculation of cohorts’ sample sizes (e.g., statistical power). the understanding of the benefits of tf-bap fitted with powered knees can be extended by other studies focusing on: functional outcomes; 3d dynamic, kinematic, kinetic; metabolic characteristics; and participant’s experience (e.g., device weight and noise).17,21,27,67 furthermore, there is a need to establish the cause-effect relationships between loading characteristics and confounders related to demographics, amputation history, prosthetic arrangement, walking ability as well as the strength and safety of boneimplant coupling.61,68-74 finally, new systematic reviews and meta-analyses relying on advanced statistical approaches are required to determine the loading variability associated with components currently recommended for tf-bap as well as their efficacy and safety (e.g., walking pace, weight acceptance, propelling load).13,73 conclusion benchmark loading data for a powered knee currently recommended for tf-bap is provided for the first time. altogether, the spatiotemporal gait characteristics and the propelling loads suggested that fitting the power knee alongside pro-flex (xc, lp) and balance s prosthetic feet may restore distinctly the capacity of participants fitted a transfemoral osseointegrated implant to ambulate. indicative comparisons with the literature suggested that the loading profile applied with this combination of components is more suitable than n-mpks and stacked up against recent p-mpks. therefore, one can argue that a routine transition from n-mpks or p-mpks onto the power knee appears safe and potentially effective. as listed above, this is the third study applying this protocol to assess ecological tf-bap prosthetic loading. this protocol can facilitate cross-comparison of loading characteristics between studies. however, further standardization requires a consensus around loading criteria likely to warrant efficacy and safety of tf-bap components (e.g., weight acceptance, propelling loading). these efforts might also contribute to the design of iso norms for osseointegrated implants and bap-specific components. in the meantime, this study producing level iv evidence, participated in evidence-based prescription of tf-bap fitted with powered knees. hopefully, this work will also contribute to the developments of standard of care for growing population of individuals using bionic limbs. acknowledgements the authors wish to acknowledge felix starker and valentina betti from össur, iceland; jason adams from össur, americas; and christopher lavender and nicholas marchand from össur, canada, for their contributions to the development of this project, as well as dan milius and miriam grant from apc prosthetics pty ltd for their valuable assistance in organizing the data collection. the authors also thank the participants of this study for their valuable contribution. declaration of conflicting interests • laurent frossard received compensation for the study design, data collection and processing as well as writing of the manuscript. • stefan laux has no conflict of interest. • marta geada has no conflict of interest. • lisa tronicke is employed by össur that provided the components. https://doi.org/10.33137/cpoj.v8i2.45790 13 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 • thor fridriksson is employed by össur that provided the components. • knut lechler is employed by össur that provided the components. authors’ contribution • laurent frossard: conceptualization, methodology, software, validation, formal analysis, investigation, resources, data curation, writing original draft, writing review & editing, visualization, supervision. • stefan laux: conceptualization, methodology, validation, investigation, resources, writing review & editing, supervision, funding acquisition. • marta geada: conceptualization, methodology, validation, investigation, resources, writing review & editing, funding acquisition. • lisa tronicke: conceptualization, methodology, supervision, project administration, funding acquisition. • thor fridriksson: conceptualization, resources, project administration, funding acquisition. • knut lechler: supervision, project administration, funding acquisition. sources of support this study was solely funded by össur, iceland. össur has had no influence upon the design, data collection, analysis, or interpretation of this research study and no involvement in the decision to publish these results. references 1.rehani m, stafinski t, round j, jones ca, hebert js. boneanchored 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clin orthop relat res. 2025; 483(5):902-14. https://doi.org/10.1097/corr.0000000000003344 64.kannenberg a, zacharias b, mileusnic m, seyr m. activities of daily living: genium bionic prosthetic knee compared with c-leg. j prosthet orthot. 2013; 25(3). https://doi.org/10.1097/jpo.0b013e31829c221f 65.lura dj, wernke mm, carey sl, kahle jt, miro rm, highsmith mj. differences in knee flexion between the genium and c-leg https://doi.org/10.33137/cpoj.v8i2.45790 http://dx.doi.org/10.1186/s12984-019-0625-6 https://doi.org/10.1109/tro.2022.3152134 https://doi.org/10.1186/s12938-016-0287-6 https://doi.org/10.1186/s12938-016-0287-6 https://doi.org/10.3389/fnins.2018.00134 https://doi.org/10.1016/j.dib.2019.104195 https://doi.org/10.3109/03093649709164538 https://doi.org/10.1097/jpo.0000000000000028 https://doi.org/10.1097/jpo.0000000000000280 https://doi.org/10.1016/j.jbiomech.2014.01.048 https://doi.org/10.1097/jpo.0b013e3182a8a922 https://doi.org/10.1682/jrrd.2012.08.0135 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refine the rehabilitation program. clin biomech (bristol). 2008; 23(10):1243-50. https://doi.org/10.1016/j.clinbiomech.2008.06.012 69.helgason b, palsson h, runarsson tp, frossard l, viceconti m. risk of failure during gait for direct skeletal attachment of a femoral prosthesis: a finite element study. med eng phys. 2009; 31(5):595-600. https://doi.org/10.1016/j.medengphy.2008.11.015 70.newcombe l, dewar m, blunn gw, fromme p. effect of amputation level on the stress transferred to the femur by an artificial limb directly attached to the bone. med eng phys. 2013; 35(12):1744-53. https://doi.org/10.1016/j.medengphy.2013.07.007 71.prochor p, frossard l, sajewicz e. effect of the material's stiffness on stress-shielding in osseointegrated implants for boneanchored prostheses: a numerical analysis and initial benchmark data. acta bioeng biomech. 2020; 22(2): 69-81. https://doi.org/10.37190//abb-01543-2020-02 72.ahmed k, thornton m, taylor sjg. mechanical load applied by intraosseous 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https://doi.org/10.1016/j.medengphy.2008.11.015 https://doi.org/10.1016/j.medengphy.2013.%2007.007 https://doi.org/10.37190/abb-01543-2020-02 https://doi.org/10.1016/j.medengphy.2023.104097 https://doi.org/10.3389/fbioe.2023.1237919 https://doi.org/10.1186/s13018-024-04944-0 17 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 appendix the supplement provides information about the confounders (e.g., selection criteria, alignment of instrumented prostheses, position of the percutaneous part and prosthetic knee in relation to the transducer, setup, number of steps analyzed), the dispersion and magnitude of extrema for each activity as well as comparative values for demographics, spatiotemporal variables, loading boundaries and loading extrema extracted from the literature. confounders table s1: selection criteria applied for the recruitment of participants with unilateral transfemoral bone-anchored prosthesis. a-inclusion criteria 1. to be willing to participate to this project of research 2. to be willing to comply with protocol 3. to be between 18-80 years of age 4. to be fitted with osseointegrated fixation more than 6 months prior testing 5. to be fully rehabilitated 6. to be able to walk 200 meters independently with prosthesis 7. to be able to be fitted with the nominated össur components 8. to be a previous or current user of microprocessor-controlled knee 9. to have a clearance of at least 6-8 cm between connector attached to distal end of percutaneous part of the fixation and prosthetic knee joint to fit the transducer b-exclusion criteria 1. to not be able to give informed consent 2. to have mental illness or intellectual impairment 3. to have major uncorrected visual deficit 4. to have history of epilepsy or recurrent dizziness 5. to have bilateral amputation 6. to have self-reported pain level greater than 4 out of 10 at study outset 7. to have experienced a fall within the last 8 weeks before assessment 8. to present signs of infection 2 weeks prior testing session 9. to have injuries involving contralateral (intact) limb table s2: position of the distal end of connector attached to the percutaneous part and the geometrical centre of the power knee in relation to the origin of coordinate system of ipecslab’s transducer (rtc electronics, usa) on the antero-posterior (ap), medio-lateral (ml) and vertical (vt) axes. participant distal end of the percutaneous part centre of the power knee ap ml vt ap ml vt (cm) (cm) (cm) (cm) (cm) (cm) 1 0.63 -0.46 9.19 -0.67 -0.36 -8.20 2 2.19 0.72 9.91 -1.85 -1.33 -9.93 3 -0.22 0.00 9.08 -0.79 -0.59 -8.83 4 0.77 -1.20 8.12 0.39 1.16 -8.14 5 -0.61 0.01 8.86 -1.06 -0.85 -8.08 6 3.80 -0.59 8.23 -0.51 0.15 -8.56 7 0.63 -0.73 8.77 1.41 1.19 -8.60 8 -1.29 0.22 9.92 2.66 -0.81 -7.70 9 -2.02 0.72 8.69 -0.83 -1.13 -8.36 10 -0.87 0.16 12.08 -0.43 -0.82 -8.74 11 1.65 -0.44 8.59 1.29 0.54 -8.54 12 2.67 0.09 9.79 1.72 0.69 -7.84 13 2.52 0.16 13.41 0.33 -0.23 -7.79 mean 0.76 -0.10 9.59 0.13 -0.18 -8.41 sd 1.74 0.56 1.54 1.31 0.85 0.58 https://doi.org/10.33137/cpoj.v8i2.45790 18 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 table s3: description of non-experimental facilities. activities power knee straight level walking location indoor length (m) 14 ascending and descending ramp location indoor length (m) 5.70 incline (deg) 3.72 handrail height (m) 0.93 ascending and descending stairs location indoor number of steps 10 step height (cm) 17 step depth (cm) 29.5 step width (cm) 1,130 handrail height (m) 1 table s4: overview of number of participants (n) and gait cycles (gc) analyzed during the assessment with the instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s). activity participation number of gait cycles (n, (%)) (gc) level walking 13 (100%) 538 ascending ramp 12 (92%) 230 descending ramp 12 (92%) 265 ascending stairs 7 (54%) 137 descending stairs 7 (54%) 157 total 13 (100%) 1,327 https://doi.org/10.33137/cpoj.v8i2.45790 19 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 figure s1: overview of six load-related outcomes susceptible to have a cause-effect relationship between the usage of the bone-anchored prosthesis (e.g., onset, magnitude and duration of loading) and the nine most frequent adverse events. adapted from reference 4, and 5. figure s2: example of instrumented transfemoral bone-anchored prostheses including position and orientation of tri-axial transducer coordinate system of the portable kinetic system (ipecslab, rtc electronics, usa) for participant 1. o: origin of the transducer coordinate system, lg: long axis, ap: antero-posterior axis, ml: medio-lateral axis, r: residuum, i: percutaneous part of the implant, c: connector, t: transducer, k: prosthetic knee. https://doi.org/10.33137/cpoj.v8i2.45790 20 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 figure s3: individual alignment of the instrumented bone-anchored prosthesis fitted with ipecslab’s transducer (rtc electronics, usa) instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) and footwear for the cohort of 13 participants. p a rt ic ip a n t 5 p a rt ic ip a n t 6 p a rt ic ip a n t 1 p a rt ic ip a n t 2 front view back view side view front view back view side view p a rt ic ip a n t 3 p a rt ic ip a n t 4 p a rt ic ip a n t 7 p a rt ic ip a n t 8 https://doi.org/10.33137/cpoj.v8i2.45790 21 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 figure s3 (continued): individual alignment of the instrumented bone-anchored prosthesis fitted with ipecslab’s transducer (rtc electronics, usa) instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) and footwear for the cohort of 13 participants. front view back view side view front view back view side view p a rt ic ip a n t 9 p a rt ic ip a n t 1 0 p a rt ic ip a n t 1 1 p a rt ic ip a n t 1 2 p a rt ic ip a n t 1 3 https://doi.org/10.33137/cpoj.v8i2.45790 22 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 figure s4: position of the distal end of connector attached to the percutaneous part and the geometrical centre of the power knee in relation to the origin of coordinate system of ipecslab’s transducer (rtc electronics, usa) on the antero-posterior (ap), medio-lateral (ml) and vertical (vt) axes of the sagittal and frontal planes. https://doi.org/10.33137/cpoj.v8i2.45790 23 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 front view side view front view side view participant 1 participant 2 participant 3 participant 4 participant 5 participant 6 participant 7 participant 8 participant 9 participant 10 figure s5: individual position of the distal end of connector attached to the percutaneous part and the geometrical centre of the power knee in relation to the origin of ipecslab’s transducer (rtc electronics, usa) on the antero-posterior (ap), medio-lateral (ml) and vertical (vt) axes of the front and side views in the image (ics) and transducer (tcs) coordinate systems. https://doi.org/10.33137/cpoj.v8i2.45790 24 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 participant 11 participant 12 participant 13 figure s5 (continued): individual position of the distal end of connector attached to the percutaneous part and the geometrical centre of the power knee in relation to the origin of ipecslab’s transducer (rtc electronics, usa) on the antero-posterior (ap), medio-lateral (ml) and vertical (vt) axes of the front and side views in the image (ics) and transducer (tcs) coordinate systems. https://doi.org/10.33137/cpoj.v8i2.45790 25 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 level walking detection of local extrema figure s6: dispersion (cross) and average (circle) for first (red), second (bleu) and third (green) points of interest of forces and moments for cohort of participants (n=13) fitted instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during walking (538 gait cycles). https://doi.org/10.33137/cpoj.v8i2.45790 26 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 characteristics of local extrema figure s7: box plots showing low and high 95% confidence interval, mean and outliers of the magnitude of up to three local extrema (pt1, pt2, pt3) of forces and moments for cohort of participants (n=13) fitted instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during walking (538 gait cycles). https://doi.org/10.33137/cpoj.v8i2.45790 27 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 ascending ramp detection of local extrema figure s8: dispersion (cross) and average (circle) for first (red), second (bleu) and third (green) points of interest of forces and moments for cohort of participants (n=12) fitted with instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during ascending ramp (230 gait cycles). https://doi.org/10.33137/cpoj.v8i2.45790 28 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 characteristics of local extrema. figure s9: box plots showing low and high 95% confidence interval, mean and outliers of the magnitude of up to three local extrema (pt1, pt2, pt3) of forces and moments for cohort of participants (n=12) fitted with instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during ascending ramp (230 gait cycles). https://doi.org/10.33137/cpoj.v8i2.45790 29 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 descending ramp detection of local extrema figure s10: dispersion (cross) and average (circle) for first (red), second (bleu) and third (green) points of interest of forces and moments for cohort of participants (n=12) fitted with instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during descending ramp (265 gait cycles). https://doi.org/10.33137/cpoj.v8i2.45790 30 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 characteristics of local extrema figure s11: box plots showing low and high 95% confidence interval, mean and outliers of the magnitude of up to three local extrema (pt1, pt2, pt3) of forces and moments for cohort of participants (n=12) fitted with instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during descending ramp (265 gait cycles). https://doi.org/10.33137/cpoj.v8i2.45790 31 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 ascending stairs detection of local extrema figure s12: dispersion (cross) and average (circle) for first (red), second (bleu) and third (green) points of interest of forces and moments for cohort of participants (n=7) fitted with instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during ascending stairs (137 gait cycles. https://doi.org/10.33137/cpoj.v8i2.45790 32 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 characteristics of local extrema figure s13: box plots showing low and high 95% confidence interval, mean and outliers of the magnitude of up to three local extrema (pt1, pt2, pt3) of forces and moments for cohort of participants (n=7) fitted with instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during ascending stairs (137 gait cycles). https://doi.org/10.33137/cpoj.v8i2.45790 33 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 descending stairs detection of local extrema figure s14: dispersion (cross) and average (circle) for first (red), second (bleu) and third (green) points of interest of forces and moments for cohort of participants (n=7) fitted with instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during descending stairs (157 gait cycles). https://doi.org/10.33137/cpoj.v8i2.45790 34 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 characteristics of local extrema figure s15: box plots showing low and high 95% confidence interval, mean and outliers of the magnitude of up to three local extrema (pt1, pt2, pt3) of forces and moments cohort of participants (n=7) fitted with instrumented prosthesis (i.e., power knee, pro-flex lp, pro-flex xc, balance s) during descending stairs (157 gait cycles). https://doi.org/10.33137/cpoj.v8i2.45790 35 frossard l, laux s, geada m, tronicke l, fridriksson t, lechler k. evidence-based recommendation of a powered knee for transfemoral bone-anchored prostheses: a cross-sectional study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 2, no. 4. https://doi.org/10.33137/cpoj.v8i2.45790 canadian prosthetics & orthotics journal issn: 2561-987x evidence-based approach to powered knee use in bone-anchored prostheses frossard et al., 2025 comparative values table s5: mean and standard deviation of gait and load characteristics produced with a non-microprocessor-controlled knee (n-mpk) total knee and passive microprocessor-controlled knee (p-mpk) rheo knee xc during walking and the active microprocessor-controlled knee (ampk) power knee. sd: standard deviation, n: number of participants, bmi: body mass index, lor: length of residuum, %snd: percentage of sound thigh length, s: second, %gc: percentage of gait cycle, f: force, m: moment, lg: long axis, ap: anteroposterior axis, ml: mediolateral axis, %bw: percentage of bodyweight. n-mpk (a)15,16,25 p-mpk (b) 6, 26 power knee (c) (mean±sd) (mean±sd) (mean±sd) a-population demographics participants (n) 6 13 13 male (n) 2 11 13 female (n) 4 2 0 age (yrs) 51 ± 6 57±14 64 ± 13 height (m) 1.75 ± 0.20 1.78 ± 0.08 1.79 ± 0.06 mass (kg) 75.94 ± 16.94 86.31 ± 18.03 93.65 ± 15.54 bmi (kg/m2) 23.38 ± 2.70 25.92 ± 4.73 27.63 ± 4.18 amputation cause trauma (n) 4 9 11 tumor (n) 1 2 2 infection (n) 0 2 0 other (n) 1 0 0 left (n) 2 5 5 right (n) 4 8 8 time since amp (yrs) 28 ± 17 17 ± 19 11 ± 9 time since bap (yrs) 5 ± 2 2 ± 2 6 ± 3 lor (cm) 20.36 ± 4.87 28.38 ± 5.69 33.62 ± 4.91 lor (%snd) 49 ± 8 63 ± 11 71 ± 10 b-spatio-temporal variables cadence (strides/min) 47 ± 4 47 ± 6 49 ± 13 duration gait cycle (s) 1.29 ± 0.11 1.34 ± 0.22 1.27 ± 0.31 duration support (%gc) 56 ± 2 63 ± 4 63 ± 5 c-loading boundaries (d) flg (%bw) 86 ± 6 102 ± 7 102 ± 7 fap (%bw) 14 ± 4 20 ± 7 16 ± 5 fml (%bw) 11 ± 4 7 ± 3 10 ± 4 mlg (%bwm) 0.48 ± 0.26 0.73 ± 0.33 0.88 ± 0.44 map (%bwm) 2.91 ± 0.87 3.44 ± 0.98 3.61 ± 1.07 mml (%bwm) 2.52 ± 0.93 4.13 ± 1.21 3.41 ± 1.29 d-loading extrema weight acceptance flg1 (%bw) 86 ± 6 102 ± 7 102 ± 7 fap1 (%bw) -9 ± 4 -11 ± 4 -10 ± 4 fml1 (%bw) 11 ± 4 7 ± 3 10 ± 4 mlg1 (%bwm) -0.41 ± 0.22 -0.43 ± 0.29 -0.53 ± 0.34 map1 (%bwm) -2.91 ± 0.87 -3.44 ± 0.98 -3.61 ± 1.07 mml1 (%bwm) -1.85 ± 0.42 -0.75 ± 0.68 -0.85 ± 1.03 propelling loads fap2 (%bw) 14 ± 2 20 ± 7 16 ± 5 mlg2 (%bwm) 0.48 ± 0.26 0.73 ± 0.33 0.88 ± 0.44 mml2 (%bwm) 1.44 ± 1.05 4.10 ± 1.25 3.32 ± 1.37 mml3 (%bwm) -2.43 ± 0.72 -2.47 ± 1.01 -2.27 ± 0.64 (a) including polycentric total knee 1900 = 6 fitted with trustep = 3, c-walk = 2 or unknown = 1 prosthetic foot components extracted from 15,16,25 (b) including rheo knee xc = 13 fitted with pro-flex lp = 7 or pro-flex xc = 4 prosthetic foot components; (c) including power knee = 13; pro-flex lp = 7, pro-flex xc = 4, or balance s = 2 prosthetic foot components; (d) absolute maximum magnitude. https://doi.org/10.33137/cpoj.v8i2.45790 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 1 2025 research article steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i1.45122 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 research article using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study steinberg r.j1,2 *, robinson l.r1,3,4,5, kachmarchuk o1, jankey s6, posa s1, mayo a.l1,3,4, simon m7, kiss a8, mackay c5,6,9,10, simpson r1,4,5.11,12, wasilewski m.b1,5,13, dilkas s4,6, hitzig s.l1,5,13,14 1. st. john's rehab research program, sunnybrook research institute, sunnybrook health sciences centre, toronto, canada. 2. consultation/liaison psychiatry, adult psychiatry and health systems, sunnybrook health sciences centre, toronto, canada. 3. division of physical medicine & rehabilitation, department of medicine, sunnybrook health sciences centre, toronto, canada. 4. physical medicine and rehabilitation, temerty faculty of medicine, university of toronto, toronto, canada. 5. rehabilitation sciences institute, temerty faculty of medicine, university of toronto, toronto, canada. 6. west park healthcare centre, university health network, toronto, canada. 7. st. john’s rehab hospital, sunnybrook health sciences centre, toronto, canada. 8. institute of health policy, management and evaluation, university of toronto, toronto, canada. 9. department of physical therapy, temerty faculty of medicine, university of toronto, toronto, canada. 10. school of rehabilitation therapy, queen’s university, kingston, canada. 11. institute of health and wellbeing, university of glasgow, glasgow, united kingdom. 12. toronto rehabilitation institute, university health network, toronto, canada. 13. department of occupational science and occupational therapy, temerty faculty of medicine, university of toronto, toronto, canada. 14. dalla lana school of public health, clinical public health division, university of toronto, toronto, canada. introduction lower extremity amputations (lea) are a debilitating event that can negatively affect an individual’s physical and mental health.1-3 although there are many factors that lead to lea, approximately 80% are dysvascular in etiology and attributed to complications of diabetes and/or peripheral arterial disease.4-6 compared to other limb loss populations open access abstract background: individuals with lower extremity amputations (lea) often face high rates of depression and anxiety that hinder their rehabilitation and post-discharge coping. group therapy is a clinically and costeffective way to address these mental health challenges, but evidence for its use with lea inpatients is limited. objective: to determine the feasibility of a psychosocial group therapy intervention for individuals with dysvascular lea undergoing inpatient rehabilitation. methodology: this randomized controlled trial randomly assigned dysvascular lea rehabilitation inpatients into a supportive-expressive group therapy (segt) or a treatment as usual (tau) group. the segt intervention, a form of group therapy adapted from outpatient medical settings, consisted of six one-hour sessions held twice weekly over a three-week period. participants completed baseline, exit and three-month surveys assessing the study’s secondary outcomes of segt effectiveness on depression, anxiety, coping, body image, health, and community participation. the main outcomes assessed recruitment, survey completion, treatment adherence, and participant retention rates. interviews and a focus group were completed to obtain feedback on the intervention. findings: twenty-five participants were recruited, with 12 randomly assigned to the segt group, and 13 to the tau group. the average number of sessions attended by segt participants was 3.9 (sd = 2.1). the survey completion rates for all participants were 84% (21/25) for the baseline assessment, 64% (18/25) for discharge, and 44% (11/25) for the three-month follow-up. the segt group showed a significant improvement in anxiety and depression scores (p = 0.02). segt was well-received by participants and staff. conclusion: the findings suggest a larger pragmatic segt trial is feasible, despite a small sample size and implementation challenges during the covid-19 pandemic, given this study achieved moderate rates of recruitment, retention, and survey completion. several critical insights were gained on how to optimize an inpatient group therapy intervention for dysvascular lea populations in rehabilitative settings. article info received: april 2, 2025 accepted: may 11, 2025 published: may 24, 2025 citation steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i 1.45122 keywords psychotherapy; amputation; group; amputees; feasibility studies; mental health; rehabilitation; dysvascular; prosthetics. * corresponding author: dr. rosalie j. steinberg, msc, md, frcpc affiliation: st. john's rehab research program, sunnybrook research institute, sunnybrook health sciences centre, toronto, canada. e-mail: rosalie.steinberg@sunnybrook.ca orcid id: https://orcid.org/0000-0002-5042-1378 telephone: 1-416-480-4089 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 1, article no. 4. 2025 https://doi.org/10.33137/cpoj.v8i1.45122 https://doi.org/10.33137/cpoj.v8i1.45122 https://doi.org/10.33137/cpoj.v8i1.45122 mailto:rosalie.steinberg@sunnybrook.ca https://orcid.org/0000-0002-5042-1378 https://jps.library.utoronto.ca/index.php/cpoj/index 2 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 (e.g., traumatic etiology), people with dysvascular lea have been shown to have poorer quality of life,1 and higher rates of post-morbid complications including depression, anxiety and impaired body image.1,7,8 a comorbid diagnosis of depression is associated with lower prosthetic use, higher perceived vulnerability, and lower self-rated health.9 individuals with lea undergoing inpatient rehabilitation may receive psychiatric consultations, but individual assessments can be time-consuming and costly.10,11 group therapy is a less-resource intensive mental health intervention, whereby one or more healthcare providers can treat a group of patients simultaneously.12 there is some preliminary evidence that group therapy may be beneficial for inpatients.13-15 for instance, one randomized clinical trial reported that lea inpatients experienced improvements in anxiety, depression and body image after participating in group therapy.15 similarly, a three session group therapy intervention for limb loss inpatients of mixed etiologies (trauma, dysvascular), including upper limb amputation, found that group therapy participants showed significantly lower distress levels than participants in the comparison group.13 in one study, however, the etiology of the sample was not described,15 and the other used a comparison group of discharged patients who were residing in the community.13 as such, the variable features of these studies makes generalizability to inpatients with dysvascular lea somewhat challenging. to assess the applicability of a group therapy model of care for dysvascular lea inpatients, the primary aim of this study was to evaluate the feasibility of implementing a novel supportive-expressive group therapy (segt) program for inpatients with dysvascular lea. segt is one type of group therapy that has been previously used in patients with medical illness16-18 which provides emotional, social and cognitive support. the secondary aim was to assess whether these segt sessions had any effect on mental health outcomes, with the expectation that segt participants would demonstrate measurable symptomatic improvements compared with those participants assigned to a treatment as usual (tau) condition. methodology this two-armed feasibility trial was conducted between october 2021 and february 2023. a feasibility trial design was selected since there are only two studies13,15 regarding the use of group therapy for dysvascular lea populations in an inpatient rehabilitation setting. the research ethics board at the sunnybrook health sciences centre approved the study, and it was registered at clinicaltrials.gov (id# nct05082870). participants were randomly assigned to either a supportiveexpressive group therapy (segt) group or to a treatment as usual (tau) group. it was hypothesized that an inpatient segt intervention would be feasible, and that a larger pragmatic trial could be developed as a result. the goal was to recruit 50 inpatients, with 25 randomized to the tau group and 25 randomized to the segt group. to minimize contamination between cohorts, cluster randomization was used to have tau and segt cohorts occur in different months; thereby minimizing the likelihood that segt participants would overlap with tau participants. this was done in order to reduce the possibility that participants from different cohorts could discuss the study conditions with each other. a blinding protocol was followed to create the randomization using an online randomizer (https://www.randomizer.org/) consisting of six blocks (three for segt; three for tau). participants participants were recruited from the cardiac and amputee unit at st. john's rehab, sunnybrook health sciences centre (ontario, canada). the inclusion criteria were: • adult inpatient aged 18 years or older; • have a dysvascular lea; • no clinical suspicion of cognitive impairments or a severe mental health diagnosis (e.g., schizophrenia, dementia, active psychosis); • english-speaking. patients were excluded if actively suicidal or were unable to participate in a group setting (e.g., actively using substances, exhibiting threatening behavior). study arms there were two study arms: 1) tau and 2) segt. 1) the tau group received standard care while admitted to hospital, which included care from an interdisciplinary team of rehabilitation professionals. the average length of stay for patients is four weeks, during which they are cared for by a team of nurses and hospitalists and are fitted and trained to use their prosthetics/orthotics under the supervision of prosthetists, occupational therapists, physiotherapists and a physical medicine and rehabilitation physician (physiatrist). additional services from social work and nutrition services are also provided where required. any tau participants who required psychiatric care were also provided with mental health support from a psychiatrist who was not part of the study team. 2) segt was previously designed for patients with potentially life-threatening illnesses, including hiv and cancer patients, and has demonstrated efficacy in facilitating adjustment and coping while decreasing psychological distress in these populations.16-18 this segt program, usually delivered longitudinally in an outpatient setting, was adapted for lea inpatients to enable and encourage participants to openly express and manage illness/disability-related emotions, increase social support, https://doi.org/10.33137/cpoj.v8i1.45122 https://www.randomizer.org/ 3 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 enhance relationships, improve symptoms and enhance body image. the treatment aims to facilitate mutual support and discussion of issues that are uppermost in patients' minds rather than imposing pre-determined topics for discussion. for this study, the segt group participated in six one-hour sessions, held twice weekly over a three-week period. the course of treatment and number of sessions were designed to align with the average length of stay for lea inpatients. the sessions were co-delivered by a psychiatrist and occupational therapist, and were framed within social cognitive theory19 whereby resilience to adversity (limb loss in this instance) relies on personal enablement.20 please see appendix a for a high-level summary of the salient topics raised by participants during the segt sessions. these topics closely align with the main foci or goals of the segt model previously defined in the literature.21 after the intervention, patients were provided with a patientfocused resource booklet created by the study team, which included resources on topics such as phantom pain, community support groups and coping. primary outcomes the primary outcomes were on metrics related to the feasibility of implementing an inpatient segt trial for dysvascular lea, which included: (1) participant recruitment, retention, and follow-up rates; (2) treatment adherence; (3) survey completion rates (target set at 70%); (4) completion rates of one-month post-intervention interview (target set at 50%). secondary outcomes with regard to the secondary goal of determining the effectiveness of segt, the following surveys were administered to all participants in the study. • coping self-efficacy scale (cses) measures perceived self-efficacy for coping with challenges and threats.22 • hospital anxiety and depression scale (hads) is a 14-item depression and anxiety screening tool that asks participants to rank the severity of their depression and anxiety symptoms.23 • short form-36 survey (sf-36) is the most widely used health-related quality of life tool.24 the tool measures eight domains related to social, physical and mental health. • amputee body image scale-revised (abis-r) is a measure of body image perception in people living with limb loss.25 • reintegration to normal living index (rnli) assesses involvement in recreational and social activities perceived ability to move within the community, and the degree of comfort people have with their relationships.26 qualitative interviews with the segt participants and a focus group with healthcare providers working on the amputee unit were undertaken to better understand which factors may have influenced study feasibility, and the potential impact of segt on wellbeing and quality of life post-lea. specifically, segt participants were asked to describe what they liked or disliked about the intervention, what benefits (if any) were obtained by taking part, and any recommendations for improvement. providers were asked about their views of the potential impact of segt for patient care and its feasibility within inpatient settings. procedure within three days of admission, all eligible lea inpatients were approached by a member of their care team to determine if they were interested in participating. patients who expressed interest in the study were then referred to the research team and a research coordinator obtained informed consent. data were collected on patients’ socio-demographics and impairment and all participants were approached to complete a battery of surveys (cses, hads, sf-36, and abis-r), within the first week of admission, at 24-72 hours post-discharge or segt completion, and at three months post-discharge. at three months post-discharge, participants also completed the rnli. all participants were provided with a $25 gift card for participation. near the end of the study, the time window to collect discharge surveys was expanded to enhance the ability to capture additional data, as well as to inform our goal of informing the development of a future pragmatic trial. this protocol change was initiated due to challenges with contacting participants within 72 hours and other logistical issues (e.g., staff turnover). this change led to some of the discharge assessments (n = 7) being completed one month post-discharge, instead of the 72 hours outlined in the protocol. one month after discharge, segt participants were also invited to complete the semi-structured interview. interviews were conducted over the phone or over zoom and took approximately 30 minutes (see appendix b for the interview guide). additionally, staff were invited to participate in an in-person focus group about their perspectives on segt, which took approximately 45 minutes. both the interviews and focus group were recorded and transcribed for analysis. sample size and analysis since this was a feasibility trial, a large sample size was not needed to adequately power statistical null hypothesis testing. a sample of 25 per group was deemed sufficient for the present trial as sample size of 12 per group is generally accepted as being sufficient for a pilot study.27 https://doi.org/10.33137/cpoj.v8i1.45122 4 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 descriptive statistics were used to evaluate the primary outcome measures. for the secondary outcome measures, a statistician who was blinded to group allocation conducted the analyses using t-tests. participants with more than 20% missing data on a survey were excluded from analysis. for the qualitative interview and focus group data, the investigation team did not see the interview data until the trial ended to minimize bias. a narrative research approach28-30 was used to summarize the key insights by patients with lea and clinical staff regarding the segt intervention. a study team member used an open coding framework to identify core issues related to perceived benefits and implementation considerations. results the study was initiated in october 2021 and ended in february 2023; with 35 patients with dysvascular lea identified as potential participants. ten patients declined to participate because they were not interested (n = 8), not comfortable in participating (n = 1) or had a clinical suspicion of a cognitive impairment (n = 1). in total, 25 patients (mean age: 64.6 years; range: 42–79 years) agreed to participate, with 13 being randomized to tau and 12 to segt. eighteen of the participants were male and seven were female, with the majority of participants (n = 18; 72%) identifying as white (north american or european). the leading cause for the lea was diabetes (n = 13; 52%), and most participants underwent a unilateral below the knee amputation (n = 16; 64%). table 1 presents the sample characteristics by study group. of the 25 participants who consented, 21 participants completed the entire set of surveys for the baseline assessments and four participants (two in tau; two in segt) only completed a portion of the baseline assessments. following baseline surveys, one participant in the segt group was withdrawn due to covid-19 precautions. for the discharge assessments, 18 participants were successfully contacted; 16 (eight in segt; eight in tau) fully completed their discharge assessments and two tau group participants partially completed the discharge assessments. for the three-month follow-up, 11 participants were successfully contacted, and completed the full set of assessments. overall, 11 participants (five in tau and six in segt) completed the full course of the surveys (see consort diagram for more details). the survey completion rates were 84% for the baseline assessment, 64% for the discharge assessment, and 44% for the three-month follow-up assessment. the consort flow diagram is described in figure 1. for the segt intervention, the mean number of sessions attended was 3.9 sessions (sd = 2.1). four participants attended all six sessions, two attended five sessions, two attended three sessions, three attended two sessions, and one was withdrawn due to covid-19 before attending any sessions. the main reasons for missed sessions included covid-19 related absences (including illness and lockdowns), patients being transferred to different hospitals for medical reasons, and family visits. in total, only one segt participant completed the full course of the study, including all the segt sessions, surveys and the interview. table 1: socio-demographic and impairment characteristics. demographics segt (n = 12) tau (n = 13) age, mean (sd) 65.1 (10.5) 64.1 (9.7) gender, n (%) female 3 (25.0) 4 (30.8) male 9 (75.0) 9 (69.2) cause of amputation, n (%) diabetes 8 (66.7) 5 (38.5) peripheral vascular disease 3 (25.0) 3 (23.1) ischemia/embolism 1 (8.3) 4 (30.8) other 0 1 (7.7) level of amputation, n (%) below knee (bka) 8 (66.7) 8 (61.5) above knee (aka) 4 (33.3) 2 (15.4) bilateral aka 0 2 (15.4) bilateral bka 0 1 (7.7) racial group, n (%) white (north american or european) 8 (66.7) 10 (76.9) south asian 2 (16.7) 1 (7.7) black-caribbean 1 (8.3) 1 (7.7) mixed heritage 0 1 (7.7) hispanic 1 (8.3) 0 living situation, n (%) living alone 4 (33.3) 5 (38.5) living with others 8 (66.7) 8 (61.5) education, n (%) high school or less 4 (33.3) 6 (46.2) greater than high school 8 (66.7) 7 (53.8) employment, n (%) working 1 (8.3) 2 (15.4) not working 11 (91.7) 11 (84.6) marital status, n (%) married 6 (50.0) 6 (46.2) not married 6 (50.0) 7 (53.8) due to the low survey completion rates at the three-month follow-up, t-tests were conducted to examine only baseline and exit data. the analysis of the secondary outcomes found no statistical significance between groups except on the hads, whereby the segt group showed a significant improvement (p = 0.02; see table 2). it should be noted that the abis-r had a high number of missing values as a result of most participants leaving more than half the items blank, which did not allow for an analysis of this outcome measure. as well, there were no significant differences in rnli scores between the groups (segt m = 16.7; tau m = 17.2), which was only collected at the three-month follow-up. for the qualitative component of the trial, which was only offered to the segt group, six participants completed their one-month post-discharge semi-structured interview. all of the interviewed participants indicated they enjoyed participating in the group because it allowed them to socialize and form social connections with peers. for instance, one participant (id#5022 [male, age 63]) noted: “i think the sessions created an opportunity to open up and embrace other people, and learn about other people, and understanding that basically we’re all here on a journey and we’re going through things that we can all relate to.” https://doi.org/10.33137/cpoj.v8i1.45122 5 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 many of the patients reported they experienced benefits from the sessions, such as getting out of their rooms, and hearing about the experiences of their peers. regardless of the reason, participants reflected on how the group enabled them to increase comfort with disclosing their emotions. “i think i might cry, but you guys taught me. if you’d ask me a year ago, would i share what i’m feeling, i would’ve said no. i’d keep it in, i wouldn’t tell anybody, and i would work it out in my own head…and i think, thinking back, all those guys in that room, it made me realize i can be vulnerable and i can open up” id#5008 (male, aged 57). additionally, the topics discussed during the sessions were viewed by most participants as offering information that was useful and relevant to their lives. even in cases when people did not feel the information was applicable to them personally, the group stimulated opportunities for personal reflection and mutual support. table 2: mean change scores on secondary outcomes and p-values for cses, hads, sf-36, and abis-r. outcome group n baseline / exit change score (sd) pvalue cses segt 10 -7.46 0.37 tau 8 8.94 hads (depression) segt 9 -0.11 0.74 tau 8 0.38 hads (anxiety) segt 9 -4.39 0.02* tau 8 -0.75 sf-36 pcs segt 23 30.05 0.97 tau 24 30.13 sf-36 mcs segt 23 56.12 0.16 tau 24 59.95 abis-r segt n/a n/a n/a tau n/a n/a cses: coping self-efficacy scale; hads: hospital anxiety and depression scale; sf-36 pcs: short-form 36 physical component summary; sf-36 mcs: short-form 36 mental component summary; abis-r: amputee body image scale-revised; segt: supportive-expressive group therapy; tau: treatment as usual; n/a: not available; * significant difference. assessed for eligibility (n = 35) randomized (n = 25) tau group (n = 13) segt group (n = 12) baseline survey (n = 13) baseline survey (n = 12) discharge survey (n = 8) discharge survey (n = 10) three-month follow-up (n = 5) three-month follow-up survey (n = 6) one-month post discharge interview (n = 6) excluded (n = 10) • declined (n = 8) • ineligible (n = 2) lost to followup (n = 5) lost to followup (n = 3) withdrawn from study due to covid-19 (n = 1) lost to follow-up (n = 1) enrollment lost to follow-up (n = 3) withdrew: did not understand questions (n = 1) lost to follow-up (n = 4) recruited and consent obtained (n = 25) allocation study participation figure 1: consort flow diagram. https://doi.org/10.33137/cpoj.v8i1.45122 6 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 in terms of recommendations, participants indicated they would have liked additional sessions (e.g. more than six) and to have larger group sizes. in particular, having someone with lived experience with limb loss who is further along in their recovery journey to join the group and share their post-discharge experience was seen as an important factor for gaining insight into adaptive coping. one participant (id#5008 [male, age 57]) suggested: “i would’ve changed just one thing. i would’ve had a former patient in there the entire way, and just let them interject when they felt they needed to with the group. i think that would’ve helped me a lot, just to hear the truth... i want to hear that when i go home, i could hit a brick wall, i could do this, this could happen, this could happen.” as well, participants also requested additional educational resources outlining what their recovery and discharge may look like. for the focus group, seven clinical staff took part, which included an occupational therapist (n = 1), nurses (n = 2), and physiotherapists (n = 4). staff noted that a large number of patients are admitted with comorbid mental health and psychosocial challenges and that there is not enough mental health/psychosocial support offered to them. for instance, one staff (id#pa2) commented: “they usually have a lot of underlying mental health, psychosocial issues to begin with before the amputation. a lot of them, actually, in the lower socioeconomic status situation before they come. so, in terms of the support of mental health, they need a lot of practical support in terms of housing, funding for equipment, funding for transportation.” importantly, they expressed concerns about the lack of mental health follow-up once patients were discharged into the community due to difficulty accessing community resources. as for feasibility feedback for the group sessions, staff suggested that sessions occur in the afternoon to minimize conflict with their physical therapy and that more sessions be offered per week to increase opportunities for patient socialization. staff also suggested implementing a system for patients to continue with sessions during outbreaks (e.g., use of tablet devices to move the group online when needed). echoing the desires that the lea participants expressed, staff suggested increasing the total number of sessions and providing more resources and educational materials on limb loss and recovery. overall, the staff felt the group sessions were helpful and suggested continuing with them in an outpatient capacity to support the patients when they are discharged. discussion the primary aim of this study was to collect feasibility data for an inpatient segt trial designed to help support the mental health needs of rehabilitation inpatients with lea. although in normal circumstances the feasibility of this study may be questioned, its completion during the covid19 pandemic with moderate rates of recruitment and session attendance, along with moderate to low survey completion rates, suggested that a larger trial would be feasible but should be modified to address some of the implementation challenges we encountered throughout the course of the trial (e.g., expanding the time frame to collect discharge data). this conclusion is supported by the qualitative feedback provided by participants and staff, while also accounting for contextual factors (e.g., covid19) in relation to feasibility outcomes.31 for instance, while the initial target sample size was 50 participants (25 for each group), several challenges primarily related to the covid19 pandemic (e.g., outbreaks and work from home policies) led to the recruitment of only 25 participants. this situation was not unique as several studies globally were disrupted by the pandemic.32,33 it should be noted that almost all of the participants referred to the study met the inclusion criteria, which indicates that the parameters set for participation were well-suited for this population. without a pandemic, recruitment would likely have been more robust. other feasibility trials of psychosocial interventions in individuals with lea have reported a wide range of recruitment rates, from as low as 19% to as high as 79%.34-37 however, additional research is needed to establish appropriate recruitment and survey completion rates when evaluating the feasibility of delivering a group intervention to an inpatient dysvascular lea population. regarding the study assessments, the a priori target for survey completion was set at 70%. this target was exceeded at the baseline assessment (84%) but not met at study exit (64%) or at the three-month follow-up (44%). the moderate rates of completion for discharge and the low rates at the three-month follow-up were attributed to research staff not being able to contact participants just prior to or following their discharge. for a future trial, loss to follow-up could be mitigated by extending the time-window to contact participants after discharge from three days to one week (as patients are frequently engaged with other preand post-discharge appointments). additionally, the outcome measure related to body image (abis-r) had high rates of missing data, which suggests participants may have found this measure difficult to complete. body image issues post-limb loss are well-documented,1,7 and group therapy has been shown to help persons cope,15 but further work is needed to determine if the lack of response to the abis-r was related to participants’ not wanting to reflect on this topic or factors associated with the measure itself. with regard to group session attendance rates for the segt group, the average attendance was 3.9 sessions (sd = 2.1), with 50% attending five or more sessions. again, the main https://doi.org/10.33137/cpoj.v8i1.45122 7 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 factor for low attendance was related to factors associated with the covid-19 pandemic. for example, the second segt group cohort was cancelled after three sessions due to an outbreak on the inpatient unit. for future studies conducted during any type of outbreak, one recommendation is to offer participants virtual sessions if inperson sessions are not feasible. there is some evidence suggesting that it is feasible to switch from in-person to virtual segt but further work is needed to establish and validate best practices.38,39 the secondary measures were largely inconclusive except for a larger change score in depression and anxiety by the segt group compared to the tau condition; suggesting that taking part in segt may lead to an improvement in mood, which aligns with the findings of other group therapy interventions for persons with disabilities40, as well as for individuals with limb loss.15 while promising, it is possible that this finding is due to chance as a result of the lack of power from having a small sample size and missing data; all of which limits the generalizability of this finding. there may also be a dose effect, which can only be measured if the segt intervention was extended beyond the initial six sessions. an adequately powered pragmatic trial would help determine the effectiveness of a delivering an segt intervention for dysvascular lea. participants with lea and clinicians also offered several suggestions on ways to improve the feasibility and acceptability of the segt intervention. this included adding more sessions, delivering the group later in the day, increasing group size, adding more educational material as well as having overlapping cohorts, whereby newly admitted patients could interact with those closer to discharge. there are several limitations with the present study. first, the covid-19 pandemic created a number of operational disruptions in terms of recruitment, delivery of the segt intervention, and follow-up with patients regarding discharge assessments. although not a primary objective, the survey data related to the secondary outcomes is inconclusive, with only the depression and anxiety scales showing some initial promise. due to a protocol adjustment toward the end of the study, some of the participants completed their discharge assessments a few days after discharge, while others completed them a month after discharge. this discrepancy may have affected survey scores given that some participants had an extended time of being at home. due to the large degree of missing data at follow-up, examining potential confounders was not possible. as such, we cannot conclusively determine the clinical benefits of segt over standard care, but qualitative data provides some insights about the therapeutic value of segt. importantly, while our sample had some participants from diverse backgrounds, the majority were white and english-speaking, and further work is required to explore segt’s applicability for participants with different cultural attitudes, expectations and needs. finally, the study protocol was relatively well-adhered to, although some deviations did occur due to the pandemic. to account for these unexpected challenges for future trials, it would be beneficial to extend the initial recruitment windows and the timeframe for survey completion. despite these limitations, critical insights have been obtained to inform the development of a pragmatic trial, which is currently being pursued (clinicaltrials.gov id: nct05798091) and that has incorporated some of the suggested modifications derived from our qualitative investigations (i.e., open–ended recruitment, continuous weekly sessions). the outcomes of the pragmatic trial will provide additional evidence on whether segt is a clinically valid approach for this population. conclusion this study provides evidence for the feasibility of a segt intervention, a form of group therapy, for inpatients with dysvascular lea undergoing rehabilitation. these findings provide a number of important insights on how to better implement a segt program for lea inpatients, with some qualitative data outlining its perceived benefits. further work is needed to determine the clinical validity of segt for lea, and to further explore implementation considerations to optimize its’ delivery. acknowledgements the authors would like to thank the participants for their support of the study. declaration of conflicting interests rosalie j. steinberg, lawrence r. robinson, sharon jankey, amanda l. mayo, marina b. wasilewski, robert simpson, crystal mackay, steven dilkas and sander l. hitzig were the recipients of a sunnybrook alternative funding plan (afp) innovation grant that funded the present study. oksana kachmarchuk, stephanie posa, mindy simon and alex kiss received funding from the apf innovation grant to support their involvement in the study. the authorship team has no other conflicts of interest to declare. authors’ contribution • rosalie j. steinberg: conceptualization (lead), funding acquisition (lead), methodology, writing – original draft preparation, supervision. • lawrence r. robinson: conceptualization (supporting), methodology, supervision. • oksana kachmarchuk: project administration, writing – review & editing. • sharon jankey: conceptualization (supporting), writing – review & editing. https://doi.org/10.33137/cpoj.v8i1.45122 8 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 • stephanie posa: project administration, writing – review & editing. • amanda l. mayo: conceptualization (supporting), writing – review & editing. • mindy simon: project administration, writing – review & editing. • alex kiss: formal analysis. • crystal mackay: conceptualization (supporting), writing – review & editing. • robert simpson: conceptualization (supporting), writing – review & editing. • marina b. wasilewski: conceptualization (supporting), writing – review & editing. • steven dilkas: conceptualization (supporting), writing – review & editing. • sander l. hitzig: conceptualization (supporting), funding acquisition (supporting), methodology, writing – review & editing, supervision. sources of support funding for this trial was provided from a sunnybrook alternative funding plan (afp) innovation grant. references 1.amtmann d, morgan sj, kim j, hafner bj. health-related profiles of people with lower limb loss. arch phys med rehabil. 2015;96(8):1474-83. doi: 10.1016/j.apmr.2015.03.024 2.pezzin le, dillingham tr, mackenzie ej. rehabilitation and the long-term outcomes of persons with trauma-related amputations. arch phys med rehabil. 2000;81(3):292-300. doi: 10.1016/s00039993(00)90074-1 3.turner ap, meites tm, williams rm, henderson aw, norvell dc, hakimi kn, et al. suicidal ideation among individuals with dysvascular lower extremity amputation. arch phys med rehabil. 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orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 24.ware j, kosinski m, dewey j. how to score version two of the sf-36 health survey. lincoln, ri: qualitymetric inc; 2000. 25.gallagher p, horgan o, franchignoni f, giordano a, maclachlan m. body image in people with lower-limb amputation: a rasch analysis of the amputee body image scale. am j phys med rehabil. 2007;86(3):205-15. doi: 10.1097/phm. 0b013e3180321439 26.wood-dauphinee sl, opzoomer ma, williams ji, marchand b, spitzer wo. assessment of global function: the reintegration to normal living index. arch phys med rehabil. 1988;69(8):583-90. 27.flight l, julious sa. practical guide to sample size calculations: an introduction. pharm stat. 2016;15(1):68-74. doi: 10.1002/pst. 1709 28.wang cc, geale sk. the power of story: narrative inquiry as a methodology in nursing research. int j nurs sci. 2015;2(2):195-8. 29.renjith v, yesodharan r, noronha ja, ladd e, george a. qualitative methods in health care research. int j prev med. 2021;12:20. doi: 10.4103/ijpvm.ijpvm_321_19 30.clandinin d. handbook of narrative inquiry: mapping a methodology. thousand oaks, california 2007. available from: https://methods.sagepub.com/book/handbook-of-narrative-inquiry 31.mellor k, albury c, dutton sj, eldridge s, hopewell s. recommendations for progression criteria during external randomised pilot trial design, conduct, analysis and reporting. pilot feasibility stud. 2023;9(1):59. doi:10.1186/s40814-023-01291-5 32.sohrabi c, mathew g, franchi t, kerwan a, griffin m, soleil cdmj, et al. impact of the coronavirus (covid-19) pandemic on scientific research and implications for clinical academic training a review. int j surg. 2021;86:57-63. doi: 10.1016/j.ijsu. 2020.12.008 33.volpe m, ralli m, isidori a. the impact of the covid-19 pandemic on research activities: a survey of the largest italian academic community. plos one. 2024;19(6):e0304078. doi: 10.1371/journal.pone.0304078 34.hoevenaars d, holla jfm, te loo l, koedijker jm, dankers s, houdijk h, et al. mobile app (wheels) to promote a healthy lifestyle in wheelchair users with spinal cord injury or lower limb amputation: usability and feasibility study. jmir form res. 2021;5(8):e24909. doi: 10.2196/24909 35.trevelyan eg, turner wa, summerfield-mann l, robinson n. acupuncture for the treatment of phantom limb syndrome in lower limb amputees: a randomized controlled feasibility study. trials. 2016;17(1):519. doi: 10.1186/s13063-016-1639-z 36.mayo al, cheung b, li j, jean s, vijayakumar a, hitzig sl, et al. feasibility of a yoga intervention in an inpatient limb loss rehabilitation program. can prosthet orthot j. 2024;7(1):43896. doi: 10.33137/cpoj.v7i1.43896 37.rothgangel a, braun s, smeets r, beurskens a. feasibility of a traditional and teletreatment approach to mirror therapy in patients with phantom limb pain: a process evaluation performed alongside a randomized controlled trial. clin rehabil. 2019;33(10):1649-60. doi: 10.1177/0269215519846539 38.lutz w, edelbluth s, deisenhofer ak, delgadillo j, moggia d, prinz j, et al. the impact of switching from face-to-face to remote psychological therapy during the covid-19 pandemic. psychother psychosom. 2021;90(4):285-6. doi: 10.1159/000515543 39.simon n, cunningham e, samuel v, waters c. videoconference-delivered group acceptance commitment therapy for perinatal mood and anxiety disorders: facilitators views and recommendations. j reprod infant psychol. 2024;42(4):700-14. doi: 10.1080/02646838.2023.2180143 40.steinberg r, posa s, pattni n, wasilewski mb, robinson lr, jankey s, et al. psychosocial group therapy interventions for patients with physical disabilities: a scoping review of implementation considerations. rehabil psychol. 2023;68(3):23560. doi: 10.1037/rep0000491 https://doi.org/10.33137/cpoj.v8i1.45122 https://methods.sagepub.com/book/handbook-of-narrative-inquiry 10 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 a p p e n d ix appendix appendix a: id# date: dd / mm / yyyy patient interview guide thank you for agreeing to participate in an interview. for this interview, we are hoping to gain a better understanding of your experience with your participation in the research study testing a new group therapy approach for inpatients with limb loss at st. john’s rehab. the questions listed below are intended to guide our conversation and may vary slightly depending on how that conversation unfolds. throughout the interview, please feel free to share as much or as little as you feel comfortable with. to start off, i want to learn a little bit about who you are and your initial experiences with losing your limb(s). 1. please tell me a little more about where you are from, where you live, your family, etc.? 2. please tell me what led to you needing to have your limb(s) amputated? 3. what were you feeling or thinking about before you had to undergo the surgery for your amputation? • what were your top concerns or needs? • how did healthcare providers meet those needs/concerns? now i want to focus on your experience at st. john’s rehab for your limb loss rehabilitation care. 4. could you tell me what happened when you arrived at st. john’s rehab? • what happened when you arrived? • how were you feeling? • what was helpful during this time? • what made things more difficult? 5. what types of mental health or social supports did you receive? • were you seen by a social worker or psychiatrist? why were you referred to them? these questions will focus on your experience of taking part in the psychosocial group at st. john’s rehab. 6. when you were first approached to take part in the study, what were your thoughts about participating in a group therapy? • why were you interested in taking part? • what concerns, if any, did you have about it? • what were you expecting it to look like? 7. please describe the types of activities you did as part of the group? • how many sessions did you participate in? if you missed any, why was that? 8. what were the most beneficial aspects of taking part in the group? • what do you feel went well? why? • were your expectations met? • why do you think this aspect was beneficial? 9. what were the least beneficial aspects of taking part in the group? • what aspects of the program could have been improved? why? • were there any aspects you feel could be removed from the program? why? • was there something the program was missing that you’d like to see added? 10. what were your top concerns and/or needs while taking part in the group? • were these concerns/needs met during your time in the program? if not, why do you feel they were not met? • how did healthcare providers meet those needs/concerns? if not, how could they have better supported you? these last set of questions will focus on your experience of transitioning back to home from rehab. 11. prior to leaving st. john’s rehab, what were your top needs or concerns? • did you feel prepared to leave? • how did healthcare providers meet those needs/concerns? if not, how could they have better supported you? 12. since you’ve left the hospital, how do you feel you are adjusting to being back at home and in your community? • what has gone well with getting back home? • what has not gone as expected or well? how have you managed or dealt with things that have not gone as planned 13. has there been anything from the group therapy program that you have applied to help you adjust to being back at home? • if so, what have you used? • if not, what do don’t you think you haven’t used it? thank you for taking the time to share your experiences. this brings us to the end of the interview questions. is there anything else you’d like to share about your experiences taking part in the therapy group or recovery that we haven’t touched on? [if yes, let participant discuss. if no, reiterate our gratitude for their time and participation] https://doi.org/10.33137/cpoj.v8i1.45122 11 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 a p p e n d ix appendix b: themes discussed during segt coping mechanisms used to deal with limb loss • participants often discussed personal coping strategies to deal with their amputation, including humor, positivity, praying, smoking, and writing. • acceptance of limb loss is adaptive, and can be considered as a stage of grief. • trying to maintain control can be adaptive or maladaptive. • relying on others for support can help with coping, but relying too much on others can drive them away (maladaptive). • it is important to find a purpose in life and to let this guide your mindset ( i.e. yoga, being athletic) • importance of mindfulness and meditation as a positive coping strategy. camaraderie with peers/peer support • participants in the group created a “brotherhood” and united in their stories of limb loss. • described finding solace and support in others who have also experienced limb loss. • during one of the sessions, each participant showed their residual limb to the group, and compared the size of wheelchairs, surgical scars, phantom pain etc. • peer comparison of experiences from acute care to rehab helps with perspective and recovery. adaptation after limb loss • discussions about how adaptable the participants are. • the idea of having to “move past the standard”— doing things differently to enjoy the same things as everyone else (i.e. driving). the importance of self-advocacy • discussion surrounding the importance of advocating for yourself during recovery. • participants encouraged each other to ask questions and encourage help-seeking. • self-advocacy can get you better care and more choices, but there is a need to ask first. • rather than depending on people to offer support, there is a growing realization that with an amputation, one may need to show initiative to ask for support. attitudes towards healthcare and clinical care • frustration around the healthcare system. • some good experience with staff, but also many discussions about frustration with the skills and perceived lack of transparency of some healthcare providers. • loss of faith in the healthcare system, feelings that the healthcare system has let them down. • difficulties with navigating the healthcare system alone and a lack of guidance from professionals. • wanting to be informed but feel like providers are not being transparent. the importance of family & support • family and friends often support amputees during their entire journey, from discussions leading up to the amputation, their recovery post-surgery, and preparing the hope (renovations). • how families often act as advocates for patients. • family as motivator--wanting to get better for family. • the “family” also includes friends who call and offer support. relationships • worries about how their amputation affects their families, which includes the trauma that families are experiencing. • friends are also struggling with the participant’s amputations. • talk about how to discuss limb loss with children in the family with the hope of normalizing the experience. • they also want spouses and family to have a support group, so they can better understand what the patient is experiencing. pain • discussions around physical pain and managing pain medications. • the idea of getting used to pain, especially chronic pain or phantom pain. • the connection between pain and mood — people can sometimes get irritable when in pain. • bonding over emotional pain — and how to manage it. • phantom pain was an important topic discussed, including the differing severity of symptoms and the use of mirror therapy to treat it. most patients in the group experience it, and it is really severe. the importance of having meaning & purpose during recovery. • participants desire to be occupied and to have a purpose. • try to stay occupied during their recovery. • feelings of helplessness and uselessness expressed throughout the recovery. • pride in having hobbies (building decks, car models). https://doi.org/10.33137/cpoj.v8i1.45122 12 steinberg r.j, robinson l.r, kachmarchuk o, jankey s, posa s, mayo a.l, et al. using a novel psychosocial group intervention to improve adaption, coping and mental health outcomes following dysvascular limb amputations: a feasibility study. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 4. https://doi.org/10.33137/cpoj.v8i1.45122 canadian prosthetics & orthotics journal issn: 2561-987x psychosocial group intervention after dysvascular amputation steinberg et al., 2025 a p p e n d ix • create a routine so it feels more like home. setbacks during recovery • discussions about procedures and medical complications that came up during their recovery. • not feeling happy with recovery due to continued pain. progress during recovery • gaining confidence and independence with improved mobility and the use of a wheelchair. • growing acceptance of their limb loss and how that changes their perspective. • even small progress is a big win. • progress improves self-confidence and dignity. loss & grief • grieving lost abilities as a result of amputation and having to adapt to a “new normal” (things they can no longer do) • having to rely completely on other people for care is a loss of dignity. • feelings around being completely helpless. loss of independence. • loss of driving license, independence and past self. • coming to terms with all of the things you can no longer do. covid difficulties • frustrations around isolation, restrictions, and delays. • missed groups due to covid restrictions/infections. faith • having faith in sunnybrook as a teaching hospital. • the idea of karma and questioning god. • feeling punished by god. • loss of faith due to limb loss. gratitude • participants discussed how grateful they were for recovering both physically and emotionally, and for social support. • grateful for having hope. • how grateful they are for the experiences at the hospital including helpful staff and supportive peers that encourage recovery. • participants were happy knowing their own injury was not worse. worries about the future • most participants agreed that they are anxious about what will happen when they are discharged. • dealing with practical day-to-day challenges and worries around handling finances. • being unprepared for discharge due to having an inaccessible home. overall feedback on group • individuals felt it was “informative” and a “nice spot” as “people listen here”. • helped them build relationships with one another, despite differences in background, future trajectories, diagnoses etc. • overall, it allowed them to learn how to relate to one another. • groups might have facilitated acceptance of one’s condition. • allowed people to open up and speak even though they normally would not have. https://doi.org/10.33137/cpoj.v8i1.45122 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). volume 7, issue 2 2024 review article williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and nonhealing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v7i2.43715 1 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 review article wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions williams-reid h1, johannesson a2, buis a1* 1 department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. 2 össur clinics emea, stockholm, sweden. introduction 1: overall rationale, aims, and objectives the term “wound” broadly refers to damage to any biological tissue,1 encompassing damage from amputation surgery to deep tissue injuries caused by loading during lower limb prosthetic use. the healthy, or normal, wound healing process is marked by four interlinked physiologic phases (table 1): i) hemostasis, ii) inflammation, iii) proliferation, and iv) tissue remodeling (or resolution).2-4 this complex process demands a high degree of cellular coordination, including several avenues through which impairments can occur. consequently, wound healing can be stalled (also referred to as non-healing, impaired, or chronic) not by one isolated factor, but by several smaller contributing issues.5 for example, common post-amputation surgical site healing complications include infection, pain, hematomas, tissue necrosis, poor residual limb formation, recurrent ulceration, wound dehiscence, and stitch abscesses.6,7 persistent complications, in other words, poor healing, can necessitate open access abstract background: following lower limb amputation, timely prosthetic fitting enhances mobility and quality of life. however, inconsistent definitions of surgical site healing complicate prosthesis readiness assessment and highlight the need for objective wound management measures. objective: this review aimed to compile definitions of healing and non-healing provided in the literature investigating biomarkers of healing of the tissues and structures found in the residual limbs of adults with amputation. methodology: a scoping review was conducted following jbi and prisma-scr guidance. searches using “biomarkers,” “wound healing,” and “amputation” were performed on may 6, 2023, on web of science, ovid medline, ovid embase, scopus, cochrane, pubmed, and cinahl databases. inclusion criteria were: 1) references to biomarkers and healing; 2) residuum tissue healing; 3) clear methodology with ethical approval; 4) published from 2017 onwards. articles were assessed for quality (qualsyst tool) and evidence level (jbi system). findings: of 3,306 articles screened, 219 met the inclusion criteria and are reviewed in this article, with 77% rated strong quality. 43% of all included sources did not define healing, while the remainder used specific criteria including epithelialization (14%), wound size reduction (28%), gradings scales (3%), scarring (1%), absence of wound complications (2%), hydroxyproline levels (0.5%), no amputation (0.5%), or neovascularization (0.5%). 84% of included sources did not provide definitions of non-healing. studies defining non-healing used criteria like wound complications (4%), the need for operative interventions (4%), or lack of wound size reduction (1%). for 10% of included sources, healing and non-healing definitions were considered not applicable given the research content. total percentages exceed 100% for both healing and non-healing definitions because some sources used two definition classifications, such as epithelialization and wound size reduction. the findings indicate a lack of standardized definitions irrespective of study type. conclusion: this review reveals significant gaps in current definitions of healing and non-healing, often based on superficial assessments that overlook deeper tissue healing and mechanical properties essential for prosthesis use. it emphasizes the need for comprehensive definitions incorporating biomarkers and psychosocial factors to improve wound management and post-amputation recovery. article info received: july 5, 2024 accepted: october 25, 2024 published: november 15, 2024 citation williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2 .43715 keywords amputation, scoping review, wound healing, wound nonhealing, surgical site healing, biomarkers, markers of healing, residuum healing, residual limb healing, wound management, impaired healing. please refer to the end of the article for a list of abbreviations & acronyms. * corresponding author: professor arjan buis, phd department of biomedical engineering, faculty of engineering, university of strathclyde, glasgow, scotland. e-mail: arjan.buis@strath.ac.uk orcid id: https://orcid.org/0000-0003-3947-293x journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 7, issue 2, article no.1. 2024 https://doi.org/10.33137/cpoj.v7i2.43715 https://doi.org/10.33137/cpoj.v7i2.43715 https://doi.org/10.33137/cpoj.v7i2.43715 mailto:arjan.buis@strath.ac.uk https://orcid.org/0000-0003-3947-293x https://jps.library.utoronto.ca/index.php/cpoj/index 2 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 revision surgeries or even re-amputation at more proximal levels.6 despite the intricacies of the wound healing process, the current assessment of healing relies mainly on surface level clinician examinations and wound classification systems. for instance, the east london nhs (national health service) trust's clinical guidelines recommend using a disposable measuring tape to monitor wound healing by assessing wound length and width.8 such subjective methods introduce biases and fail to account for underlying issues. deep tissue injuries (dtis), for example, develop subcutaneously and only become visible in later stages, manifesting as bruised purple localized areas of intact skin9 that can evolve into large deep wounds.10 this introduces the need for more objective measures to assess healing both at the surface level and below the cutaneous layer. this necessity for more objective measures is particularly pertinent in managing residual limbs following lower limb amputation. following their surgery, depending on the healing process, individuals who have undergone lower limb amputation will typically receive a customized prosthetic limb within a window of 3 to 20 weeks postsurgery.11,12 these prosthetic interventions are bespoke devices aimed to replicate the missing limb function, enhancing the user’s mobility, ambulation, and ability to perform daily tasks. consequently, they significantly improve physical health, cardiovascular well-being, mental health, quality of life, and overall independence.12,13 notably, singh and prasad14 reported that the absence of a prosthetic limb fitting is an independent predictor of mortality within three years of a major lower limb amputation, defined as the loss of the limb at or proximal to the ankle joint.15 however, assessing residuum healing and thus readiness for a prosthesis after amputation, like wound healing, remains ambiguous, involving clinician opinion, and surface level wound examination. in a narrative review of determinants of healing and readiness for prosthetic fitting after transtibial amputation, day et al.16 concluded that clinical judgement is most subjective when assessing the degree of healing. online resources for individuals with amputation similarly note that readiness for prosthetic fitting is dependent on factors such as healing, pain management, oedema, and residual limb volume,17 yet specific indicators for these factors remain undefined. even healthcare bodies like the nhs provide no clear guidelines on assessing readiness, relying instead on clinicians’ experience and judgement, which can vary widely. for instance, turner et al.18 in their thematic analysis of issues faced by prosthetists and physiotherapists during lower limb prosthetic rehabilitation, noted that clinicians lack a standardized approach to prosthetic rehabilitation. to illustrate, some prosthetists prefer removing a prosthesis to promote wound healing, whereas others believe continuing to wear it is more beneficial by encouraging blood flow.18 furthermore, recent studies suggest that a limb does not need to be fully healed to begin prosthetic rehabilitation,16 but clear guidelines for when an open surgical site is appropriate for prosthetic use are still lacking. one prosthetist emphasized18 that “we have to go at the rate of the body,” noting that limbs heal and mature at different rates, further underscoring the variability in both clinical practice and patient recovery trajectories. moreover, individuals awaiting amputation often present with multiple comorbidities that complicate their healing process. one of the most common causes of amputation is complications arising from diabetes,19 yet hyperglycemia can lead to vascular stiffening, microvascular dysfunction, reduced tissue oxygenation, and, consequently, impaired wound healing.20 the complexity of defining readiness for prosthetic rehabilitation, coupled with the lack of standardized clinical practices, suggests the need for more objective measures, such as biomarkers, to assess healing and reduce the risk of complications like revision surgeries or re-amputations. a biomarker is defined by the u.s. fda (food & drug administration) as a “defined characteristic that is measured as an indicator of normal biological processes, a pathogenic process or a response to an exposure or intervention”.21 additional scholarly works have extended the fda's definition by emphasizing the requirement for objectivity22 and the importance of accurate and reproducible measurements.23 however, to the authors’ knowledge, research into the use of biomarkers for monitoring healing and facilitating early prosthetic rehabilitation postamputation remains limited. studies that do exist, such as those focusing on changes in tissue composition during prosthetic use,24 typically examine mature residual limbs, whereas early-stage residual limbs face greater risks of complications like ulceration and volume changes, which exacerbate poor socket fit.25 research into these early stages is crucial for ensuring successful prosthetic rehabilitation and preventing further surgical interventions. table 1*: characteristics and time frames of the four primary interlinked phases of wound healing. phase characterization time frame i (hemostasis) directly after injury, there is an outpouring of lymphatic fluid and blood. this involves platelet aggregation (blood clotting) and blood vessel vasoconstriction to prevent further bleeding. seconds to hours ii (inflammation) cellular debris and bacteria are removed. vascular permeability is increased to promote the diffusion of necessary molecules to the wound site. cellular migration is similarly increased, as is chemotaxis. the aim is to limit further damage. hours to days iii (proliferation) formation of granulation tissue (the contractile organ that fills wounds that heal by second intention), reepithelization (epidermis regeneration), and neovascularization. days to weeks iv (remodeling) defined by vascular maturation and regression, and collagen remodeling. the wound reaches its maximum strength and its ultimate endpoint; in cutaneous tissue, this is marked by a collagenous scar. weeks to months *adapted from references 2-4. https://doi.org/10.33137/cpoj.v7i2.43715 3 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 this raises the following research question: what biomarkers (physical, chemical, or other) are predictive, diagnostic, and/or indicative of healing of the tissues and structures found in the residual limbs of adults with amputation? in summary, as noted by patel et al.26 advances in genomics, proteomics, and molecular pathology have led to the identification of several candidate biomarkers with potential clinical value. however, progress in this area remains slow, and there is little consensus in the literature regarding the most appropriate biomarkers for assessing healing.22 furthermore, to the authors’ knowledge, no comprehensive review exists that synthesizes biomarkers specifically related to healing after amputation. the most recent study examining readiness for prosthetic rehabilitation following transtibial amputation concluded that the only objective healing assessment used in the included studies was transcutaneous oxygen perfusion, a physical biomarker.16 the review emphasized that objective methodologies like this could quantify healing, reduce subjectivity, and promote comparative research on different enhanced recovery after surgery protocols and their effects on post-amputation healing.16 existing reviews are typically narrative in nature, discussing general wound healing biomarkers without a systematic approach, further highlighting the need for a more structured review of biomarkers specific to healing in the context of amputation and primary wound healing postsurgery. to address this gap a scoping review was developed and implemented to compile the breadth of available wound healing biomarker evidence and answer the research question. the aim of the review was therefore to identify predictive, diagnostic, and/or indicative biomarkers (physical, chemical, or other) of healing of the tissues and structures found in the residual limbs of adults with amputation. to meet this aim and answer the research question, the following objectives were compiled: 1) collate and synthesize the reported definitions of healing and non-healing in the literature investigating healing of the tissues and structures found in the residual limbs of adults with amputation. 2) identify and collate physical biomarkers predictive, diagnostic, and/or indicative of healing repeated in sources investigating healing of the tissues and structures found in the residual limbs of adults with amputation. 3) identify and collate chemical biomarkers predictive, diagnostic, and/or indicative of healing repeated in sources investigating healing of the tissues and structures found in the residual limbs of adults with amputation. 4) assess the quality and levels of evidence of sources investigating healing of the tissues and structures found in the residual limbs of adults with amputation. the term “physical” refers to biomarkers such as ph, temperature of the wound, or collagen quantity revealed through histochemical staining,27 whereas the term “chemical” refers to markers found in wound tissue, fluid, serum/blood, sebum, saliva, or sweat such as cytokines or matrix metalloproteinases (mmps). 2: part 1 rationale, aims, and objectives this article (part 1) addresses objectives 1 and 4 and is the first in a series of three articles, each of which explores objectives 1 to 3 in turn. before objective measures of healing can be developed, it is essential to first clarify the current definitions of healing. the timing of prosthetic rehabilitation, for instance, is contingent upon how healing, and consequently readiness for prosthetic fitting, is defined. likewise, effective wound management hinges on the criteria used to distinguish between a healed and an unhealed wound. however, the literature reveals a lack of consensus on the definitions of healing and non-healing wounds.28 while complete healing is often characterized by the “complete epithelialization” of the wound,29-31 this description neglects the underlying tissue layers. where definitions of healing fall short, defining non-healing may be a useful alternative. yet, definitions of impaired healing (commonly referred to as non-healing, chronic wound healing, or delayed healing) also exhibit significant variability. for instance, furuyama et al.32 define nonhealing ulcers as wounds resulting in “major amputation or death before achieving ulcer healing”, whereas another source considers a chronic wound to be one that “has not shown a 20-40% reduction in wound area after 2-4 weeks of optimal treatment”.33 relying solely on temporal criteria to distinguish healing from non-healing can be problematic. for example, research has shown that while older adults may experience delayed healing, the ultimate outcome remains comparable to that of younger individuals.34 additionally, day et al.16 found that in their review of determinants of healing and readiness for prosthetic fitting, healing was undefined in 13 of the 15 studies reviewed. they also noted that the absence of standard healing definitions, the heterogeneity of measurable endpoints, and the inconsistent reporting of healing across studies significantly hinder the extrapolation of findings. in light of these challenges, the following article aims to answer the research question: how are healing and nonhealing defined in the literature investigating biomarkers of healing of the tissues and structures found in the residual limbs of adults with amputation? the aim of this article is therefore to compile definitions of healing and non-healing that are provided in the literature investigating biomarkers of healing of tissues and structures found in the residual limbs of adults with amputation. https://doi.org/10.33137/cpoj.v7i2.43715 4 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 methodology given the novelty of the research question and the variable sources available on biomarkers, a scoping review was deemed the most appropriate method to meet the aims and objectives and answer the research question. the scoping review was based upon the joanna briggs institute (jbi) methodology for scoping reviews35-38 and implemented following the preferred reporting items for systematic reviews extension for scoping reviews (prisma-scr) checklist and guidance.39,40 all results were tracked and recorded on excel version number 2303 (microsoft, washington, usa) run on windows 11 version 22h2 (microsoft, washington, usa). a scoping review is iterative,41 with several steps requiring piloting; thus, the methodology presented in the following sections represents the final iterations of these processes. 1: inclusion criteria the following sections detail and rationalize the inclusion criteria of the scoping review culminating in the generation of an inclusion tool (table 2) used in the first and second rounds of screening. 1.1: participants to minimize the ethical considerations associated with studies involving children, given that healing in adults and children reportedly differs,42,43 only sources involving adult participants were included. in line with common practice in literature44 and uk law (the setting in which this research takes place), an adult is defined as an individual older than or equal to 18 years of age.45 a further inclusionary criterion was that participants must be experiencing some form of clearly described wound in tissues and structures comparable to that of an amputation residuum (table 3). for example, the study by giesen et al.46 meets the inclusion criteria despite focusing on risk factors, such as c-reactive protein (crp) biomarker levels, for surgical site infections (ssi) following appendectomy. ssi is relevant as it can result in a non-healing wound.47 although the infection in this case occurs at the appendix, it affects the surrounding skin and soft tissue. this tissue is biologically comparable to that found at an amputation surgical site, thereby making the findings applicable to the study’s context. 1.2: types of sources all the source types expressed in the following list were considered for inclusion to ensure the breadth of research was captured: • quantitative studies this includes any study design, including retrospective/ prospective cohort studies, randomized controlled trials (rcts),48 and in vitro, in silico, or rat/mouse studies. note that rats/mice are considered sufficiently genetically similar to humans and are often used in biological research49 and will thus be included in this review. where human participants were involved, the articles must clearly state whether ethical approval and informed consent were provided to meet the eligibility criteria. • qualitative studies • mixed studies • case studies • conference proceedings • dissertations and theses • text and opinion articles • letters to editors these may be of value given their purpose to act as a form of post-publication peer review and the platform they give researchers to share experiences with fellow readers.50 • guidelines issued by national and international wound and tissue viability associations examples of this include the national institute for health and care excellence (nice) guidance on “prontosan for treating acute and chronic wounds”51 and the nhs “wound management clinical practice guidelines”.8 however, all sources included were required to be reproducible, necessitating that their methodologies be clearly outlined. as a result, sources such as letters to table 2: inclusion criteria tool applied to each source during the first (title and abstracts) and second (full text) screening processes. to pass screening one, sources required all ‘yes’ or ‘maybe’ answers. to pass screening two on the other hand, and be included in data extraction, sources needed ‘yes’ responses to all inclusion criteria. evidence source details and characteristics citation primary author (year) title abstract inclusion criteria for screening one yes no maybe 1 does it reference biomarkers of wound healing (progression/monitoring/prediction)? 2 does it refer to healing of tissues found in the residuum? 3 is it published during or after 2017? inclusion criteria for screening two yes no 1 does it reference biomarkers of wound healing (progression/monitoring/prediction)? 2 does it refer to healing of tissues found in the residuum? 3 does the source involve human/rat/mice participants? if it involves human participants, are they over 18 years old? 4 is it published during or after 2017? 5 is the methodology clear/repeatable? 6 does the study have clear ethical approval? https://doi.org/10.33137/cpoj.v7i2.43715 5 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 editors and conference proceedings generally did not meet the inclusion criteria (figure 1). review articles were considered secondary sources and excluded. table 3: for clarity this table provides examples of tissues/ structures found in the amputation residuum and those not. examples of tissues/structures found in the residuum skin, muscle and tendons, ligaments, bone, vasculature, and the peripheral nervous system. examples of tissue/structures not found in the residuum the central nervous system, and organs like the heart, brain, stomach, intestines, etc. the extensive number of sources generated during the initial searches prompted a reassessment of the inclusion criteria. additionally, the rapid advancements in wound healing biomarkers48 underscored the necessity for more recent data. a recent scoping review examined prognostic factors (biomarkers) associated with ulcer healing, a common diabetic complication that can precede amputation,52 specifically focusing on sources published before 2017.53 in light of this context, it was decided to include only sources published in or after 2017, thereby ensuring the relevance and timeliness of the reviewed literature. 1.3: concept (interventions and outcomes) sources were required to explore biomarker(s) in conjunction with wound healing. a relationship between the biomarker (independent variable) and non-healing/healing (dependent variable) was required for quantitative, observational, and mixed studies. a result was considered conclusive when a statistical significance of p < 0.05 was achieved. however, measuring biomarkers can be a continuous or categorical variable, thus any sources using cut-off or dichotomizing/categorizing approaches were also included.48 1.4: context sources of any context (e.g., home, hospital, community, or academic institutions) and from any discipline (e.g., healthcare professionals or engineers) were considered to capture as much research as possible. similarly, provided they were in the english language due to the linguistic limitations of the primary reviewer, sources from any geographical setting were considered to minimize highincome-country (hic) and western publication bias.54,55 2: search methods for identification of sources according to the three-step search strategy recommended by jbi, an initial search was carried out on medline via ovid and pubmed to locate relevant sources and determine whether or not they could contribute to increasing search terms and keywords.56 following the generation of an exhaustive list of terms based on the research question, and search strategy piloting, the search terms detailed in table 4 were decided upon. table 4: search terms and indexing used to generate all sources screened in the final scoping review. note the proximity search “adj5” index applies only to ovid databases and differs according to the database. biomarker biomarker* marker* indicator* factor* amputation amputee* amputation* residuum* stump* limb loss wound healing wound adj5 sensing wound adj5 sensor heal/heals/healed/healing monitor/monitoring sensor/sense/sensing wound adj5 healing wound adj5 monitoring wound adj5 monitor in a scoping review of scoping reviews, pham et al.57 concluded that the most frequent limitation was the possibility of missing relevant sources, which can be attributed to database selection. to counteract this, a significant number of databases mentioned in previous scoping reviews of a similar nature48,58,59 were searched: • web of science • meldine (hosted on the ovid platform) • embase (hosted on the ovid platform) • scopus • cochrane • pubmed • cinahl all search results were exported and stored in endnote 20 (version 20.2.1, clarivate, 2021) and duplicates were removed. 3: data extraction articles that passed both screening steps and met the eligibility criteria were then subjected to data extraction. data (including study type, definitions of healing and nonhealing, wound details, sample type, sample size, and levels and quality of evidence) was extracted in accordance with the data extraction tool (appendix a). despite the debate surrounding the use of quality assessment in scoping reviews,41,60 it was decided to systematically demonstrate that the quality of evidence collated was acceptable to enhance the validation of the results of this review. the qualsyst tool (appendix b) proposed by the alberta heritage foundation61 was decided upon given that it outputs a number providing a quantitative and reproducible means of identifying quality that other critical appraisal tools do not.62 the outputted score allows a source to be categorized as limited, adequate, good, or strong quality. similarly, evidence levels were assessed using the jbi levels of evidence (appendix c). https://doi.org/10.33137/cpoj.v7i2.43715 6 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 high numbers of poor-quality and low-level evidence could be considered indicative of a need for improvements in biomarker research methods. 4: data analysis and presentation the nature of a scoping review does not lend itself to a meta-analysis, thus it is recommended that it should instead focus on basic descriptive analysis such as frequency counts of concepts. peter et al.35 further state that in some cases basic coding in a review proves useful particularly when identifying or clarifying definitions. since the objective of this review requires the synthesis of wound healing definitions, coding is justified. to explore relationships between study types and definitions of healing and nonhealings, results are subdivided into study types with frequency counts of definitions within these study types identified. extracted data is expressed in two primary formats. the first is a summary of the search results and selection process,35 including a prisma diagram. the second is the presentation of the data extracted from the included sources, in such a format that the research question is answered. results are descriptively presented in paragraphs that align with the review's objectives and are diagrammatically mapped. charts allow frequency counts to be graphically visualized. it is well-known that data visualizations enhance understanding.63 all charted data (including source references) are openly available in the review’s dataset64 stored on the university of strathclyde knowledgebase. results 1: overall results 1.1: search strategy results and included articles of the 7,041 sources generated from the search strategy (table 5), 3,735 were duplicates, so 3,306 titles and abstracts were screened (figure 1). 2,659 sources were excluded, leaving 647 for full-text screening. after exclusion, 219 articles remained and were subjected to data extraction. primary reasons for exclusion included review articles, unclear methodologies, no ethical approval, inaccessible texts, language constraints, irrelevant wound healing, and a lack of focus or discussion on biomarkers. 1.2: quality and levels of evidence all included evidence was quantitative with 77% of all studies29,31,32,46,65-229 demonstrating strong quality, and 0 studies graded with limited quality (table 6). evidence levels, on the other hand, varied more; for prognosis 35 studies were graded level 1.b (the second highest level of evidence), and 4 (table 7) were graded 5.c (the lowest level of evidence), whereas for effectiveness, 1 and 12 studies were graded 1.b and 1.c, respectively. however, 98 studies were graded 5.c (table 7). study types additionally meant that no studies were graded for meaning or economic evaluation levels of evidence. for levels of evidence, it is important to note that the total frequency counts add up to greater than 219 (the number of included articles) given that several studies were graded in more than one evidence level category; for example, often when graded for prognosis, they were additionally graded for effectiveness. interestingly, 153 (70% of 219) were graded for effectiveness, yet only 14 (6% of 219) met the criteria to be graded for diagnosis (table 7). 1.3: study types and settings the most common study type was bench research, with 99 studies of this kind and only 6 case-controlled studies (table 8). the most common setting research took place in was a university environment (190 studies), whereas only 1 study occurred in a governmental organization setting (table 9). 66 and 35 studies were conducted in medical centers and research centers, respectively (table 9). note that the counts of settings and countries exceed 219 because 76 (35%) of the articles took place in more than one setting, and 26 (12%) of articles took place in more than one country. all included articles came from 40 countries, with 56 studies affiliated with china alone (table 10). whereas, only 7 and 3 articles were based in the uk and ireland, respectively. table 5: breakdown of the search strategy results for each searched database. database search date number of results limited to abstracts, titles, keywords (specifics of the applied limit) limited to 2017 and after web of science 06/05/2023 4,924 2,087 (abstract limit) 931 ovid medline 06/05/2023 2,942 2,852 (abstract limit) 1,086 ovid embase 06/05/2023 4,050 3,934 (abstract limit) 1,818 scopus 06/05/2023 4,534 4,534 (title, abstract, keyword limit) 1,828 pubmed 06/05/2023 3,833 2,199 (title, abstract limit) 916 cinahl 06/05/2023 1,014 505 (abstract limit) 245 cochrane cochrane reviews 06/05/2023 202 16 (title, abstract, keyword limit) 8 cochrane protocols 06/05/2023 30 0 (title, abstract, keyword limit) 0 cochrane trials 06/05/2023 318 312 (title, abstract, keyword limit) 209 total references 7,041 duplicates removed 3,735 total references to screen 3,306 https://doi.org/10.33137/cpoj.v7i2.43715 7 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 identification of studies via databases and registers records identified from 7 databases (n = 7,041) records screened (n = 3,306) reports sought for retrieval (n = 647) reports assessed for eligibility (n = 646) studies included in review (n = 219): • part 1 – review of healing and non-healing definitions (n = 219) • part 2 – review of physical biomarkers (n = 157) • part 3 – review of chemical biomarkers (n = 203) records excluded (n = 2,659) reports not retrieved (n = 1) reports excluded (n = 427): • full methodology and results not sufficiently clear: • clinical trial registry (n = 26) • conference/meeting abstract (n = 101) • letter to editor (n = 2) • article commentary or supplement (n = 2) • study proposal (n = 2) • short report (n = 1) • review articles (n = 133) • does not discuss biomarkers (n = 50) • does not discuss wound healing (n = 28) • does not correlate biomarkers with wound healing (n = 19) • wound healing is discussed in tissue not relevant to the residuum (n = 17) • duplicates (n = 6) • dataset only (n = 3) • doi not recognized (n = 3) • no ethical approval stated (n = 2) • patent only (n = 2) • study published before 2017 (n = 2) • includes participants below 18 years old (n = 1) id e n ti fi c a ti o n s c re e n in g in c lu d e d duplicates removed (n = 3,735) figure 1: prisma (preferred reporting items for systematic reviews and meta-analyses) flow diagram of the scoping review screening process. table 6: ranking criteria for scores generated using the qualsyst quality assessment tool61 and numbers of included sources that obtained these rankings (na = not applicable). quality threshold scores number (%) of included sources references of included sources percentage (%) of maximum possible score quality < 50% limited 0 (0%) na ≥ 50% and < 70% adequate 9 (4%) 231, 234, 235, 241, 253, 263, 270, 272, 274 ≥ 70% and < 80% good 41 (19%) 230, 232, 233, 236-240, 242-252, 254-262, 264-269, 271, 273, 275-279 ≥ 80% strong 169 (77%) 29, 31, 32, 46, 65-229 https://doi.org/10.33137/cpoj.v7i2.43715 8 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 2: definitions 2.1: healing definitions as depicted in figure 2, 43% (n = 95) of included sources (all study types) provided no definition of healing. when definitions were provided, healing was most explained by complete epithelization/healing and change in wound area/size, utilised in 14% (n = 30) and 28% (n = 61) of sources respectively. changes in wound area were most often used in bench research studies (92% of included sources using this definition) and were commonly presented as a wound healing rate defined as follows (equation (1)): wound healing rate (%) = s0-st s0 × 100% where s0 is the original wound area, and st refers to the wound area at any given time after injury. interestingly only one source242 incorporated biomarkers in their definition of healing, using ohp (hydroxyproline) levels as a surrogate marker of healing in their randomized control trial table 7: levels of evidence of the included articles in accordance with the jbi levels of evidence (appendix c) (jbi = joanna briggs institute; na = not applicable). evidence level jbi evidence level study categories effectiveness diagnosis prognosis 1.a 0 0 0 1.b 1 (237) 10 (75, 85, 94, 130, 144, 158, 176, 231, 232, 234) 35 (29, 31, 68, 74-76, 81, 83, 85, 87, 94, 97, 100, 102, 124, 132, 144, 158, 171, 175, 176, 179, 191, 195, 198, 201, 203, 206, 230-236) 1.c 12 (103, 105, 136, 163, 212, 238-244) na na 1.d 0 na na 2.a 0 0 0 2.b 0 0 0 2.c 0 na na 2.d 0 na na 3.a 0 0 0 3.b 1 (159) 0 50 (32, 46, 72, 73, 84, 88, 90, 91, 98, 104, 106, 109113, 118, 123, 125, 126, 128, 130, 138, 139, 141-143, 148, 149, 154, 156, 161, 166, 184, 185, 187, 188, 194, 197, 211, 213, 214, 216, 220, 274-279) 3.c 3 (77, 232, 268) na na 3.d 3 (151, 183, 269) na na 3.e 34 (31, 69, 75, 76, 84, 99, 102, 106, 109, 113, 114, 116, 121, 122, 125, 130, 144, 149, 153, 158, 176, 179, 185, 196, 198, 199, 201, 224, 234, 235, 270273) na na 4.a 0 0 0 4.b 0 0 2 (93, 151) 4.c 0 na na 4.d 1 (89) na na 5.a 0 0 0 5.b 0 0 0 5.c 98 (65-67, 70, 71, 78-80, 82, 86, 92, 95, 96, 107, 108, 115, 117, 119, 120, 127, 129, 131, 133-135, 137, 140, 145-147, 150, 152, 155, 157, 160, 162, 164, 165, 167-170, 172-174, 177, 178, 180-182, 186, 189, 190, 192, 193, 200, 202, 204, 205, 207210, 215, 217-219, 221-223, 225-229, 245-267) 4 (75, 85, 94, 231) 4 (101, 127, 131, 178) table 8: study types of all included articles. study type number (%) of included sources references of included sources bench research 99 (45%) 65-67, 70, 71, 78-80, 82, 86, 92, 95, 96, 101, 107, 108, 115, 117, 119, 120, 127, 129, 131, 133-135, 137, 140, 145-147, 150, 152, 155, 157, 160, 162, 164, 165, 167-170, 172-174, 177, 178, 180-182, 186, 189, 190, 192, 193, 200, 202, 204, 205, 207-210, 215, 217-219, 221-223, 225-229, 245-267 observational study retrospective 52 (24%) 32, 46, 72, 73, 84, 88, 90, 91, 98, 99, 104, 106, 109-113, 118, 123, 126, 128, 130, 138, 139, 141-143, 148, 149, 154, 156, 159, 161, 166, 171, 184, 187, 188, 194, 197, 211, 213, 214, 216, 220, 224, 274-279 prospective 49 (22%) 29, 31, 68, 69, 74-77, 81, 83, 85, 87, 94, 97, 100, 102, 114, 116, 121, 122, 124, 125, 132, 144, 153, 158, 175, 176, 179, 191, 195, 196, 198, 199, 201, 203, 206, 230-236, 268, 270-273 randomized controlled trial (rct) 13 (6%) 103, 105, 136, 163, 212, 237-244 case-controlled study 6 (3%) 89, 93, 151, 183, 185, 269 https://doi.org/10.33137/cpoj.v7i2.43715 9 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 investigating the effects of topical negative pressure (tnp) therapy on tissue oxygenation and wound healing in vascular foot wounds. a further 6 sources68,76,149,163,237,244 (all human participant studies) added a more systematic approach to the definition of healing than others through the implementation of grading systems/scales such as the wagner scale or the university of texas classification system. chen et al.,237 in their randomized controlled trial, defined a healed ulcer as wagner grade 0 (skin intact, but bony deformities lead to “foot at risk”282) and 1 (superficial ulcer). lee et al.163 evaluated residual limb incision healing using a modified bates-jensen score (mbjs) assessment tool, scoring the following criteria from 1 to 5: amputation skin color, epithelization, amount of exudate, and the presence and volume of eschar. higher scores therefore indicate worse healing. in fact, jeon et al.,149 in their observational retrospective study, employed and compared five classification systems for diabetic foot ulcers (meggittwagner classification; sinbad [site, ischemia, neuropathy, bacterial infection, and depth] score; depa [depth of ulcer, extent of bacterial colonization, phase of ulcer, and association etiology] scoring system; ut [university of texas] diabetic wound classification; duss [diabetic ulcer severity score]) to identify the “gold standard” prognostic classification system or optimum prediction tool for amputation. 2.2: non-healing definitions over 80% (n = 183) of included sources provided no definition of impaired or non-healing wounds (figure 3). in the limited sources (all were human participant studies) where a definition was stated, the identification of wound healing complications (table 11), increase or no change in table 9: setting in which the included articles took place. note that university includes university hospitals and some sources took place in more than one setting. setting university medical center research center governmental organization number of included sources 190 66 35 1 references 29, 31, 32, 65-73, 75-81, 83-87, 89-93, 95-108, 110-113, 115123, 125-157, 159, 161, 163177, 179-182, 184-195, 197, 199-210, 212-229, 231-240, 243, 244, 246-250, 252-255, 259-269, 272, 273, 275, 277, 278 22, 29, 31, 32, 46, 72, 74, 76, 78, 82, 85, 88, 90, 91, 93, 99, 100, 105, 109, 114, 123, 125, 128-130, 136, 138, 139, 148, 151, 154, 158, 167, 172, 175, 179, 194-198, 201-203, 205-207, 211, 214, 216, 228, 230, 232, 239242, 248, 253, 255, 257, 268, 273, 274, 276, 277, 279 94, 96, 124, 141, 150, 155, 157, 160, 162, 169, 173, 174, 178, 180, 183, 184, 198, 200-202, 206, 207, 215, 228, 241, 245, 251, 255, 256, 258, 264, 267, 268, 270, 271 114 table 10: number of included sources based in each country (some studies took place in more than one country). country china usa india japan korea turkey taiwan uk italy germany no. 56 (70, 81, 95, 99, 102106, 108, 115, 119, 125, 126, 128, 129, 134, 139, 140, 143, 145, 150, 168-170, 172-174, 177, 178, 196, 203, 208, 215, 217, 218, 220-229, 245, 248, 254, 255, 259, 260, 262, 267, 273, 278) 47 (78, 83, 85, 88, 90, 92, 98, 101, 108-112, 127, 135, 137, 146, 155, 156, 160, 163, 171, 179, 181, 182, 194, 195, 199, 204-207, 213, 217, 219, 232, 246, 247, 249, 252, 257, 258, 265, 266, 268, 277, 279) 13 (94, 96, 117, 124, 191, 198, 232, 233, 236, 241, 251, 256, 261) 11 (29, 32, 138, 153, 158, 159, 161, 193, 211, 221, 276) 9 (70, 120, 149, 155, 157, 166, 187, 188, 216) 9 (68, 84, 89, 93, 97, 142, 189, 202, 275) 7 (31, 164, 165, 167, 175, 176, 237) 7 (24, 67, 148, 205, 243, 255, 281) 7 (91, 122, 130, 136, 141, 214, 264) 7 (71, 131, 174, 184, 234, 254, 278) country canada iraq brazil indonesia france pakistan cuba netherlands ireland denmark no. 5 (65, 66, 102, 123, 134) 5 (67, 87, 231, 250, 269) 5 (78, 132, 180, 204, 274) 5 (107, 151, 239, 240, 244) 4 (86, 91, 147, 201) 4 (75, 120, 230, 253) 4 (183, 268, 270, 271) 4 (46, 131, 184, 235) 3 (67, 80, 86) 3 (144, 197, 253) country saudi arabia malaysia south africa iran singapore switzerland austria nigeria poland czech republic no. 3 (190, 236, 261) 3 (154, 210, 261) 3 (79, 152, 186) 3 (185, 238, 272) 2 (209, 255) 2 (118, 131) 2 (131, 184) 2 (74, 100) 2 (77, 116) 1 (148) country egypt israel thailand lithuania greece norway romania lebanon sweden finland no. 1 (133) 1 (76) 1 (192) 1 (131) 1 (131) 1 (78) 1 (89) 1 (73) 1 (69) 1 (162) https://doi.org/10.33137/cpoj.v7i2.43715 10 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 wound size, or the need for operative interventions, explained non-healing in 4% (n = 9),83,109,112,163,179,195,206, 216,276 1% (n = 2),83,158 and 4% (n = 9)32,109,118,179,194,195,206,216, 273 of sources respectively. in none of the definitions were biomarkers used. wound complications were defined differently depending on the source, as compiled in table 11. of the 9 sources using wound complications to define non-healing, 67% (n = 6) explored healing in relation to the amputation surgical site.109,112,163,206,216,267 in addition to major amputation, furuyama et al.32 further defined ulcer non-healing in patients with critical limb ischemia by amputation or death. contrastingly kimura et al.158 defined worsened foot wounds only as wounds that had increased in size without amputation, with participants resulting in minor or major amputation, or all-cause death in the one-year study period being classified separately. in 10% (n = 22) of all included sources80,85,86,88,9496,106,121,127,144,145,169,178,183-185,205,207,234,253,279 both healing and non-healing definitions were considered not applicable given the content of the research. laiva et al.,80 for example, explore the expression of pro-angiogenic factors (characteristic of wound healing) in human diabetic adipose-derived stem cells cultured on collagen scaffolds. although this is investigating aspects of ulcer healing and is therefore relevant to the scoping review research question, it focuses on a specific cellular aspect of non-healing diabetic foot ulcers (dfus), rather than in vivo whole ulcer healing (where several tissues and cells are involved). discussion this scoping review aimed to compile definitions of healing and non-healing found in the literature investigating biomarkers of healing in the tissues and structures of residual limbs of adults with amputation. the findings indicate a significant lack of standardized definitions of healing within the literature, with only one source242 incorporating biomarkers (an objective measure rather than a subjective one) to define healing. systematic methods for quantifying healing, such as pre-defined grading systems or scales like the wagner scale, were utilized in only 2% of the studies included. moreover, these tools are generally designed for the assessment of open wound healing rather than surgical site healing. similarly, definitions of nonhealing were either absent or inconsistently characterized by varying descriptions of wound complications. the review highlights a broader lack of consensus and standardization in defining both healing and non-healing, as current definitions are often superficial and predominantly based on visual and size-based assessments. these approaches fail to consider deeper tissue healing and mechanical properties essential for functionality, particularly in the context of prosthesis use. there is a critical need for more comprehensive, multidimensional definitions that incorporate objective measures like biomarkers and mechanical assessments, along with social and psychological evaluations, to more accurately reflect the complex nature of healing to guide future research and clinical practice more effectively. 1: overall search results no set number of articles should or should not be included in a review,283 and the number of included articles comes down to the search strategy and inclusion criteria. in this review, an arguably large number of articles (219) met the inclusion criteria, whereas in the similar work by day et al.16 on determinants of healing and readiness for prosthetic figure 2: frequency counts of healing definitions provided in all included sources, categorized by study types (ohp = hydroxyproline; duss = diabetic ulcer severity score; sinbad = site, ischemia, neuropathy, bacterial infection, and depth; ut = university of texas; depa = depth of ulcer, extent of bacterial colonization, phase of ulcer, and association etiology; pedis = perfusion, extent, depth, infection, and sensation; na = not applicable). note that the total frequency equates to greater than 219 (the number of total included sources) given that some included sources encapsulated two definitions in order to define healing (e.g. change in wound area and absence of wound complications). 0 20 40 60 80 100 none provided na neovascularization complete epithelialization/healing absence of wound complications change in wound area/size complete healing documented in two consecutive visits and no amputation duss, sinbad, ut , wagner, depa, pedis, or bates-jensen scores damaged tissue replaced by healthy connective tissue, forming a scar wound healing with no granulation tissue and minimal scar tissue observed assessed using ohp frequency counts of healing definitions provided in included sources rct case-controlled observational prospective observational retrospective bench research https://doi.org/10.33137/cpoj.v7i2.43715 11 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 fitting after transtibial amputation, 2,067 articles met the search strategy yet only 20 passed both screening stages. this difference is likely due to their inclusion criteria of transtibial amputation; in this review with the knowledge that the literature on healing on amputation specifically is low, the research question was expanded to wound healing of tissues like that of the lower limb residuum, thus broadening the number of search results. of the 195 countries in the world, research from 40 of these countries was included in this review, several of which were lmics (low-to-middleincome countries such as cuba, egypt, china, malaysia, nigeria, thailand, and pakistan).284 such global research allows us to expand findings across populations, regions, and cultures,285 reduces western publication biases, and is critical in overcoming global health challenges286 like wound healing. it can be argued that the high number of countries from which research in this review originates highlights the global burden of wound healing. this is reinforced by the reported average of $2.8 billion spent globally on wound healing in 2014.287 guest et al.288 concluded that in the uk alone, between 2017 and 2018, the cost to the nhs per healed wound ranged from £698 to £3,998 per patient, and that of an unhealed wound ranged from £1,719 to £5,976 per patient. interestingly, tricco et al.,289 in their scoping review of scoping review methodologies, revealed that 423 (86%) of the articles that met their inclusion criteria did not use a quality appraisal tool in their scoping review. however, it is well reported that critical (or quality) appraisal tools are a justifiable addition to a review to systematically assess the credibility of the research on which the results of the scoping review are then based.290 on the other hand, tod et al.290 further note that quality checklists, like the qualsyst tool, lack evidence to support their use; thus, quality assessment acts as an outcome measure, not an exclusionary criterion in this review. as detailed in the results section (quality and levels of evidence) the high number of effectiveness 5.c levels of evidence can be attributed to the 99 bench research studies (almost 50% of the included articles) that were included in data extraction. of the 99 studies, 81 were rat or mouse studies, reinforcing the justification of bench research receiving the lowest level of evidence following the jbi levels of evidence. the lower number of higher-level evidence studies can be explained by the cost of studies such as rcts (estimated to cost anywhere in the range of $43 to 103,254 per patient),291 and the common lag (as long as 17 years) in translating scientific discoveries (produced through bench research) into patient studies and thus patient benefit.292 2: definitions of healing and non-healing in their review of complete wound closure definitions, gould and li28 recorded that complete/full/100% (re)epithelialization or closure was the most common definition of healing. the same was noted here, of the 102 sources (47% of all included sources) that provided definitions of healing, 30 were regarding epithelialization, and 61 were defined by changes in wound size/area. however, this assessment is limited in its applicability, particularly for surgical sites, such as amputation, which do not involve open wounds. the reliance on wound size to indicate healing, particularly through methods like measuring with disposable tapes,293 is problematic due to poor inter-rater and intra-rater reliability, its time-consuming nature, and issues inaccuracy.294-296 importantly, this focus on epithelialization alone does not capture the entirety of the healing process, as the proliferation phase, in which epithelialization occurs, is only figure 3: frequency counts of non-healing definitions provided in all included sources, categorized by study types (na = not applicable). note that the total frequency equates to greater than 219 (the number of total included sources) given that some sources encapsulated two definitions (for example macdonald et al.83 used no change in wound size and presence of wound complications) in order to define nonhealing. 0 50 100 150 200 need for operative interventions including major amputation or re-amputation wound complications increase or no change in wound size none provided na frequency counts of non-healing definitions provided in included sources rct case-controlled observational prospective observational retrospective bench research https://doi.org/10.33137/cpoj.v7i2.43715 12 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 one of four phases of wound healing. re-epithelialization occurs in the third phase, the proliferation phase (which takes place days to weeks after injury), where granulation tissue is formed, the epidermis is regenerated and neovascularization occurs.2 this phase is then followed by the fourth and final phase which occurs weeks to months after injury, remodeling, characterized by vascular maturation and regression, collagen remodeling, and the point at which a wound reaches its maximum strength and ultimate endpoint.2,3 in cutaneous tissue for example this final phase is marked by a collagenous scar. therefore, it can be argued epithelialization suggests healing but does not indicate a fully healed wound. particularly in the case of an amputation where the suture line may appear healed after re-epithelization has occurred, but the final phase of healing is still taking place below the skin and is likely heavily influenced by prosthetic use (and its subsequent mechanical loading).24 for example, bramley et al.8 conducted a study investigating changes in tissue composition and load response on 10 individuals with unilateral transtibial amputations, who had undergone the procedure between 1 and 35 years prior to the study (mean of 7.5 years) and were therefore classified as having mature residual limbs.25 the findings indicated a higher presence of adipose tissue infiltrating the muscle in residual limbs compared to intact contralateral limbs, suggesting muscle atrophy and adaptation post-amputation.8 furthermore, intramuscular adipose content was found to correlate negatively with daily prosthetic socket use, reinforcing the idea that prosthetic use influences tissue composition in mature residual limbs, and likely has an even greater impact on early healing residual limbs. therefore, a more comprehensive approach to defining healing should consider the deeper, ongoing processes beyond surface closure. definitions of non-healing were more infrequent and when provided were complex, typically focusing on the identification of complications or deviations from normal healing. one possible reason for the limited reporting of non-healing definitions is the assumption by researchers that by defining healing, non-healing is implicitly understood as the opposite. or perhaps the challenge of clearly defining non-healing is a symptom of the complexity of a chronic wound, its causes, and the variety of systemic (for example age,297, sex hormones,298 alcoholism,299 smoking,300 and nutrition301) and local (for example infection,302 oxygenation,303 and venous sufficiency304) factors that impact healing.4 it is noteworthy that among the sources surveyed, studies focusing on amputation surgical sites table 11: wound healing complications stated in non-healing definitions coded for ‘wound complications’ (rct = randomized controlled trial; clti = critical limb threatening ischemia; ssi = surgical site infection). source study type wound type non-healing definition wound complications lee et al. (163) rct amputation signs such as erythema, drainage, infection, incision breakdown, skin/fat necrosis, and/or tissue eschar. majumdar et al. (179) observational prospective surgical site after lower extremity revascularization need for operative interventions for ssi or dehiscence, or new ulcerative wound or bypass graft infection. nystrom et al. (195) observational prospective surgical site after lower extremity soft tissue sarcoma excision any wound-related issue (necrosis, dehiscence, infection, seroma) treated by a return to the operating room, initiation of oral or intravenous (iv) antibiotics, intervention for seroma including aspiration, or prolonged wound packing or dressing changes greater than 120 days. squiers et al. (206) observational prospective lower limb amputation development of necrosis; development of infection, including gangrene or abscess; ulceration occurring within or adjacent to the surgical wound; disruption or dehiscence of suture line; drainage or exudate expressed from the suture line; evidence of inflammatory response including swelling, cellulitis, or skin discoloration; hematoma formation; revision of the amputation to a more proximal level. macdonald et al. (83) observational prospective diabetic foot ulcer pain, erythema, oedema, heat, purulent exudate, serous exudate with concurrent inflammation, delayed healing, discoloration of granulation tissue, friable granulation tissue, pocketing at the base of the wound, foul odor, and wound breakdown. adams et al. (109) observational retrospective transmetatarsal amputation (1) revision of the amputation, defined as a return to the operating room for any reason; (2) postoperative infection, defined as any superficial or deep infection requiring oral antibiotics, admission to the hospital for intravenous antibiotics, and/or an unplanned return to the operating room; (3) chronic residual limb ulceration, defined as a non-healing wound at the surgical site requiring >4 weeks of wound care; (4) calcaneal gait, defined as any increased pressure at the plantar heel resulting in a pressure sore; (5) residual limb deformity, defined as a nonplantigrade foot; and (6) residual limb infarction, defined as ischemia or necrosis of the incision site. alfawaz et al. (112) observational retrospective below-knee amputation separation or necrosis of skin, flap necrosis, or dry ischemic eschar formation. morisaki et al. (276) observational retrospective above or belowknee amputation surgical site infection or wound dehiscence. woo et al. (216) observational retrospective clti patient ulcer or amputation surgical site wounds requiring regular dressing and antibiotic treatment or surgical wound revision and additional surgery. https://doi.org/10.33137/cpoj.v7i2.43715 13 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 were the primary providers of definitions for non-healing wound complications (6 of 9 included sources 83,109,112,163,179,195,206,216,276). this trend may arise from the fact that traditional definitions of open wound healing, like epithelization or wound site evaluation, do not readily apply to closed surgical site wound types. furthermore, individuals undergoing amputation often present with multiple comorbidities, such as diabetes and peripheral vascular diseases,19 and systemic factors for non-healing, such as smoking and alcohol use,305,306 which can negatively impact the healing process.20,299,300,307 for instance, lind et al.306 retrospectively examined the impact of smoking on post-operative complications in 137 patients who had undergone primary above-knee or below-knee amputations, 44 of whom were cigarette smokers. the study found that smokers had a 2.5 times higher risk of infection and re-amputation compared to non-smokers, concluding that abstaining from smoking during the postoperative healing phase is critical, as nicotine compromises cutaneous blood flow velocity and increases the risk of microthrombus formation.306 it can also be argued that healing complications such as infection or excessive oedema are primary barriers to prosthetic readiness, and thus of greater concern to prosthetists and rehabilitation professionals than indicators of healthy healing. churilov et al.,308 for example, observed that the use of rigid dressings post-transtibial amputation, hypothesized to reduce swelling and promote healing, significantly shortened the time from amputation to casting or fitting of the first prosthesis, compared to traditional soft elastic dressings. in summary, identifying abnormal healing processes, particularly in the context of amputation, requires a more comprehensive approach than surface level visual assessments. a standardized system, tailored to specific wound types, would improve the clarity and consistency of healing and non-healing definitions. a biomarker, however, would allow both healing and nonhealing to be defined and monitored objectively and quantitatively. unfortunately, only one included source242 considered a biomarker in their definition of wound healing stating that they were to “demonstrate the effects of tnp on the healing of acute wounds of the foot by measuring the change in wound volume and collagen deposition”, enlisting ohp as a well-reported surrogate marker of collagen.242 in addition to deposition during the proliferative phase of healing, collagen, a key component of the extracellular matrix, induces platelet activation and aggregation in response to injury (phase one of healing), promotes fibroblast recruitment in the inflammatory stage, and influences remodeling of the extracellular matrix (ecm) increasing the tensile strength of the wound in the final remodeling/maturation phase.309 chiang et al.242 further reported that wound volume reduction from day 0 to day 14 of treatment was not significant (44.2% tnp vs 20.9% control; p = 0.15) suggesting that tnp did not expedite wound healing as expected. similarly, the degree of collagen deposition (ohp content in tissue samples was expressed in micrograms of collagen per milligram of granulation tissue) on day 14 was also not significant between control and tnp-treated groups (58% tnp vs 94.5% control; p = 0.32).242 in terms of absolute values, the tnp group noted a larger reduction in wound size, but the control group observed a greater increase in collagen deposition. this reinforces the notion that there is more to the healing process than simply the dimensions of the open wound. thus, biomarkers could provide a more nuanced and objective means of tracking both healing and nonhealing across all wound types, including surgical sites. biomarkers have also been demonstrated in osteoarthritis research to indicate responses to loading tasks, providing valuable insights into joint health and predicting structural changes.310 this knowledge could be applied to monitoring the health of the residual limb, which undergoes adaptation during healing and early prosthetic use. for instance, in a posterior flap below-knee amputation, the gastrocnemius muscle forms a significant part of the muscle bulk covering the residual tibia. during prosthetic use, this muscle is subjected to forces in directions it would not experience in an intact limb, necessitating adaptation in response to these forces. although not utilizing biomarkers, definitions in 6 sources68,76,149,163,237,244 appeared to adopt a more systematic approach to assessing healing through the use of scales and classification systems such as the wagner (or meggitt-wagner) system. bar the modified bates-jensen (mbjs) adopted by lee et al.,163 the classifications used apply only to diabetic open wounds or ulcers and again rely only on visual/surface level assessment external to the wound, limiting their relevance to surgical wounds. diabetic foot ulcers (dfus) account for much of the research on wound healing due to their global burden, with 80% of lower extremity amputations (leas) linked to dfus.311 however, overemphasizing dfus risks overlooking the specific needs of amputation sites, which require different criteria for assessing healing. the aforementioned mbjs which evaluates necrotic tissue topes, necrotic tissue volume, exudate type, skin color surrounding the wound, and epithelialization on a scale of 1 (best healing) to 5 (worst healing),312 although designed specifically for residuum healing assessment, is also limited to observer interpretation of the surgical site. though not used in included sources, further surgical site healing classifications exist like the centers for disease control (cdc) surgical wound classification (swc)313 and the surgical wound assessment tool (swat),314 but again they incorporate only a variety of subjective observations and are focused primarily on the identification of surgical site infections only. despite being more holistic tools, these classifications still provide only subjective indicators of what is occurring under the skin and are therefore limited in truly assessing deep tissue healing; limitations that could be solved with more objective measures like biomarkers. https://doi.org/10.33137/cpoj.v7i2.43715 14 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 interestingly, all the definitions of healing and non-healing focus purely on the physical components of wound healing. the optimal healing environments (ohe) framework however suggests that patient healing is best supported by addressing not just the physical, but the social, psychological, spiritual, and behavioral components of healthcare.315 doering et al.,316 for example, observed that in 72 patients with bypass surgery, those with higher depressive symptom scores (indicating more symptoms) reported poorer emotional recovery (p < 0.001) and poorer physical recovery (p = 0.007) and achieved shorter walking distances (p < 0.001) than did patients with lower scores (indicating fewer symptoms). furthermore, by 6 weeks after discharge, infections and impaired wound healing were more common among patients with higher depressive symptom scores (46%) than among patients with lower scores (19%, p = 0.03).316 similarly, it is well known that amputation has psychological effects, with one review revealing that across 12 studies the prevalence of psychiatric disorders among amputees in india is in the range of 32% to 84%, including depression rates of 10.4% to 63% of the studied population, posttraumatic stress disorder rates of 3.3% to 56.3%, and phantom limb phenomenon rates of 14% to 92%.317 these symptoms of anxiety and depression reportedly do improve over time,317,318 yet no definitions of amputation healing detailed in this scoping review alluded to anything other than the physicality of the surgical site. perhaps in the future, more effort should be made to consider more than the physical aspects when defining healing, providing a more holistic definition of healing.315,319,320 an amputation is a lifechanging event; with more objective and well-explained definitions of healing individuals with amputations may feel more comfortable about their surgical site healing journey which is currently limited by biases introduced by the timing of clinician visits and subjective surface level wound examination only.16,321 overall, the lack of provided definitions, irrespective of evidence level, wound type, or study type, raises concerns. for example, 13 included sources were rcts (table 8), the highest level of evidence, yet of these only 6 and 1 provided healing163163,237,238,241,242,244 and non-healing163 definitions respectively. despite investigating healing, or an aspect of it, by not defining healing and non-healing the methodological rigor of the study is reduced by not providing a clear endpoint definition, and the belief that assessing wound healing is a purely visual process is perpetuated. as noted in previous studies16,321 the gap in the literature on healing definitions, particularly for amputation sites, remains unaddressed for over 20 years, despite its significance to patient outcomes. a shift toward more objective, comprehensive measures, incorporating biomarkers, psychological factors, and standardized definitions, would greatly enhance the study of wound healing in clinical settings. to develop a tailored and relevant scale for assessing wound healing in the context of residual limbs postamputation, the authors believe the following considerations should be made to ensure that it is comprehensive, objective, and clinically useful: 1. incorporate all four phases of healing, capturing both surface level and deeper tissue healing processes. 2. incorporate objective measures like biomarkers: • this will require identifying the most appropriate biomarkers for assessing post-amputation healing, potentially through a scoping review or bench research. for example, determining which biomarkers best assess the residual limb’s capacity to withstand prosthetic fitting could include indicators of healing complications like infection, inflammation, cell death, or response to mechanical loading. song et al.322 identified that inflammatory markers such as white blood cell count, serum c-reactive protein levels, and erythrocyte sedimentation rate were significantly correlated with wound healing rates in diabetic patients. additionally, thresholds or cut-off values for these biomarkers should be established to differentiate between healing and non-healing. for instance, a transcutaneous oxygen pressure (tcpo2) value below 40 mmhg has been associated with a 24% increased risk of healing complications in lower limb amputations, compared to values above 40 mmhg.323 • techniques to quantify these biomarkers must be developed or adapted. this could involve quantitative imaging techniques such as ultrasound, which has been used to observe deeper tissue changes and predict the prognosis of pressure injuries,324 or innovative tools like wearable smart bandages capable of sensing wound ph, temperature, bioimpedance, glucose, oxygen, proteins, or uric acid in real-time.325 3. include subjective and psychosocial factors: • psychological markers, such as anxiety, depression, and body image perception, should be addressed, as they influence overall recovery.316,317 a number of existing validated tools used in the lower limb amputee population are available such as the hospital anxiety and depression scale.326,327 • patient-reported outcomes (pros), such as the visual analogue scale (vas) for pain328 and the prosthetic limb users survey of mobility (plusm),329 can capture the patient’s perspective on pain, mobility, and comfort, offering deeper insights into functional recovery and prosthetic readiness. https://doi.org/10.33137/cpoj.v7i2.43715 15 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 research should explore which outcome measures most effectively reflect prosthetic readiness, perhaps through a pilot study investigating the effectiveness of different measurement tools in monitoring postamputation healing. the comet (core outcome measures in effectiveness trials) initiative provides a list of key outcome measures for studies of people undergoing major lower limb amputation for complications of peripheral vascular disease, including death, quality of life, mobility, and social integration/independence,330 which can serve as a foundation to be built upon with more objective measures like biomarkers. a multi-tiered grading system should be created, where each grade corresponds to specific milestones in the healing process, defined by clear criteria. for instance, gethin et al.331 conducted a scoping review and identified normal wound bed temperature in chronic wounds as being between 30.2°c and 33.0°c. for each criterion, clear healing versus non-healing indicators should be established, distinguishing between successful healing and complications such as infection or excessive oedema. this will require participant research to identify objective indicators of both healthy (e.g., a decrease in temperature and ph332) and unhealthy (e.g., an increase in inflammatory markers333) healing processes. the classification system must undergo rigorous pilot testing and validation. this includes: • reliability testing, ensuring high inter-rater and intrarater reliability through testing in diverse clinical settings. • construct validity testing, comparing the system against known standards to confirm its accuracy. • patient-centered validation to ensure that users’ opinions are incorporated during all stages of development to guarantee the scale addresses meaningful aspects of their recovery journey.334 in the future, automation and streamlined assessment processes could be explored, for example, potentially incorporating wearable sensors for remote monitoring of residual limb health during healing. this could enhance the scale’s practicality and accessibility. it is also essential that the scale should undergo longitudinal tracking, allowing for continuous feedback and refinement. regular updates or revisions should be made based on new research or clinical findings to reflect the evolving understanding of wound healing. by incorporating these elements, the scale will be robust, adaptable, and capable of providing both clinicians and patients with valuable insights into the healing process and readiness for prosthetic use. 3: methodological discussion 3.1: methodological strengths a scoping review appears to be the most suitable approach to answering the research question due to its ability to comprehensively explore the extensive and unclear literature on impaired and healthy wound healing biomarkers and definitions, without restrictions on source types. in contrast, a systematic review would necessitate a more narrowly defined research question. a key strength of this review is simply the significance of the conclusions drawn. by highlighting both the lack of healing definitions and the limitations within provided definitions, this systematically implemented review reinforces the need for further research into objective measures to quantify healing. the sooner we can reach a consensus on the most appropriate definition of healing (both cutaneous and subcutaneous), the sooner we can identify or predict a healing/non-healing wound, and the sooner it can be prevented or treated.22 3.2: methodological limitations despite the implementation of an exhaustive search strategy, there is always a likelihood that some sources may have been missed. therefore, it is important to remember that the results of the scoping review will guide future work; they will not influence healthcare policy, for example. a further limitation is the current lack of a second reviewer contradicting the jbi’s recommendation for a minimum of two reviewers to validate results, remove bias,35 and increase the number of relevant articles included in a review.335 however, given the nature of the authors’ resource constraints, only the primary author of this study could act as the reviewer, and the supervisory team acted as a verifier. again, it is important to consider the purpose of the review;336 for example, is it impacting policy? if so, then it is particularly pertinent to ensure the methodology and the inclusion/exclusion criteria are rigorously justified and piloted. the review reported here, although thorough, is not intended to directly impact policy, and the lack of a second reviewer is perhaps more justified. furthermore, this is not too dissimilar to peer-reviewed and published scoping reviews, with the work of tricco et al.289 (a scoping review of scoping reviews) revealing that only 34% of reviewed scoping reviews included two or more independent reviewers. yet simply introducing a standardized data extraction form, as the review reported here did, can minimize bias.35 in the future, it would be beneficial to consider using multilingual reviewers given that only sources in or translated into the english language could be investigated, potentially increasing western publication biases.54,55 the choice was made to refrain from utilizing online translation software due https://doi.org/10.33137/cpoj.v7i2.43715 16 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 to the potential risk of semantic loss. van nes et al.337 for example recommend the use of a professional translator given that translation is an interpretative act in which meaning can be lost. however, this option is costly and falls beyond the scope of the research supporting this manuscript. although including all study types ensures more relevant sources are captured, the inclusion of rodent studies and mathematical models can be questioned. in review studies, a balance between high precision (narrow) and high recall (broad) searches is necessary to ensure sufficient studies are captured by the search whilst the time required to screen all included articles is feasible.60 as such, this step was deemed unfeasible; assuming 300 articles were included with 100 references each, a further 30,000 articles would need to be screened; this was considered not an option given the limited project timescale of the primary author. please note that a registered and published protocol for this review is not available, which may influence the consistency and transparency of the review process. 4: ethical considerations the use of grey literature in reviews is a contentious topic. searching for it can be time-consuming and it lacks the validation peer-reviewed literature can provide; however, it can reduce publication bias given that it provides data that is not found in commercially published articles.338 thus, this review did aim to include grey literature however all that was generated during the searches did not meet the inclusion criteria; often failing to provide a sufficiently clear methodology and clear ethical approval. rcts are considered the highest level of evidence,280 however, they are expensive, and funding is limited. they are often industry-funded and therefore more likely to report a statistically significant positive outcome than studies without industry funding.339 thus, evidence level has not been used as an exclusionary criterion in this scoping review. it was a requirement, however, that all included articles, where applicable, clearly stated ethical approval and sought informed consent when human participants were involved. conclusion the aim of this review was to compile definitions of healing and non-healing provided in the literature investigating biomarkers of healing of the tissues and structures found in the residual limbs of adults. wound healing was predominantly characterized by epithelization and wound closure, including healing rates, or left undefined. nonhealing was often poorly explained, typically assessed by the need for operative intervention including re-amputation or signs of impaired healing when defined. this review highlights shortcomings in current definitions of healing and non-healing, which are frequently absent or based on superficial assessments influenced by clinician perspectives. these definitions mistakenly equate wound appearance and size with healing at deeper tissue levels, neglecting to account for the mechanical properties of the tissue that are critical, particularly in tissue subjected to loading during lower limb prosthesis use. this underscores the need for a more comprehensive approach to wound healing assessment, integrating biomarkers and potentially incorporating social and psychological evaluations, as a patient's environment significantly impacts their healing process. before we can enhance wound management both before and after amputation and expedite the return to daily activities, it is essential to establish a clear consensus on what defines the healing and non-healing processes. acknowledgements the author of this article would like to express appreciation to the strathclyde body device interface mechanobiology research group for their assistance in the discussion of the review’s methodology. declaration of conflicting interests the author has no conflicts of interest to declare. authors contribution • hannelore williams-reid: the primary author of the manuscript, undertook the scoping review and prepared the final manuscript as part of a 4-year phd program. • arjan buis: the primary phd supervisor, assisted in developing the scoping review methodology and preparing the manuscript for publication. • anton johannesson: the secondary phd supervisor, assisted in developing the scoping review methodology and preparing the manuscript for publication. all authors have read and approved the final version of the manuscript. sources of support the phd project under which this scoping review/manuscript falls is funded by the ukri epsrc as part of the centre of doctoral training (cdt) in prosthetics and orthotics (p&o) (studentship 2755854 "wound management and early prosthetic rehabilitation" within project ep/s02249x/1) and by össur. 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(basel). 2022;9(3). doi:10.3390/ medicines9030018 340.lee l, packer tl, tang sh, girdler s. self-management education programs for age-related macular degeneration: a systematic review. australas j ageing. 2008;27(4):170-6. doi:10.1111/j.1741-6612.2008.00298.x abbreviations & acronyms: abbreviation & acronym definition cdc centers for disease control clti critical limb threatening ischemia comet core outcome measures in effectiveness trials crp c-reactive protein depa depth of ulcer, extent of bacterial colonization, phase of ulcer, and association etiology dfu diabetic foot ulcer dti deep tissue injury duss diabetic ulcer severity score ecm extracellular matrix fda food & drug administration hic high income country iv intravenous jbi joanna briggs institute leas lower extremity amputation lmics low to middle income countries mbjs modified bates-jensen score mmps matrix metalloproteinases n number na not applicable nhs national health service nice national institute for health and care excellence ohe optimal healing framework ohp hydroxyproline pedis perfusion, extent, depth, infection, and sensation plus-m prosthetic limb users survey of mobility prisma-scr preferred reporting items for systematic review and meta-analyses for scoping reviews pros patient reported outcomes rcts randomized controlled trials sinbad site, ischemia, neuropathy, bacterial infection, and depth ssi surgical site infection swat surgical wound assessment tool swc surgical wound classification tcpo2 transcutaneous oxygen pressure tnp topical negative pressure uk united kingdom usa or us united states of america ut university of texas vas visual analogue scale https://doi.org/10.33137/cpoj.v7i2.43715 31 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 appendix appendix a: table a.1 (adapted from references 48 and 53): data extraction tool used to extract data from all sources that passed both screening steps. nast refers to data extraction categories that may not be applicable to all source types. data to be extracted clarification of data extraction category scoping review details scoping review title wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and nonhealing definitions review objectives summarized in manuscript section 1 (introduction) review questions evidence source details and characteristics citation details full harvard apa 7th edition citation for the source including source url. study type for example, an observational retrospective or case-controlled study. country the geographical location where the source was generated. setting for example, a hospital/medical center, university, or research center. one sentence summary summary of the study in one sentence. details/results extracted from the sources of evidence participant characteristics for example, age range, gender, and comorbidities. includes control group characteristics also. sample type and size refers to the number and type of participants investigated in the source (nast). wound details this includes any details about the wound type, such as classification, average size, and burn or ulcer. follow-up time refers to the time between or after reported outcome measures (nast). definition of healing definitions and terms are given for healthy (non-impaired) healing. definition on non-healing definitions and terms are given for unhealthy (impaired) healing. chemical biomarkers discussed all chemical biomarkers discussed/measured in the source must be recorded here. see manuscript introduction for a definition of chemical. physical biomarkers discussed all physical biomarkers discussed/measured in the source must be recorded here. see manuscript introduction for a definition of physical. other biomarkers discussed all remaining biomarkers that do not fall into the chemical or physical category must be recorded here. biomarker measurement techniques summary of the discussed/used/described biomarker measurement techniques used in the source. outcome measures reported outcome measures (aside from aforementioned biomarkers); for example, 3-year mortality may be the primary outcome measure. significant results results of importance as judged by the reviewers. limitations key limitations of the biomarkers, biomarker quantification technologies, or methodologies that are explicitly mentioned in the source. level of evidence level of evidence according to the jbi classification (reference 280) (see appendix c). quality of evidence quality of evidence score generated using the qualsyst tool (reference 61) (appendix b). appendix b: table b.1 (reference 61): qualsyst tool checklist for assessing the quality of quantitative studies. note that na is not an option for criteria 1, 2, 4, 13 and 14. each response is assigned a point score depending on how well it meets the criteria (“yes” = 2 points, “partial” = 1 points, and “no” = 0 points). items not applicable to a certain study design are labelled as na and excluded from the total score. a summary score is calculated by summing the total score and dividing by the possible score (the possible score is the maximum score (28 points) minus the number of “na” responses multiplied by 2). criteria yes (2) partial (1) no (0) na 1 question/objective sufficiently described? 2 study design evident and appropriate? 3 method of subject/comparison group selection or source of information/input variables described and appropriate? 4 subject (and comparison group, if applicable) characteristics sufficiently described? 5 if interventional and random allocation was possible, was it described? 6 if interventional and blinding of investigators was possible, was it reported? 7 if interventional and blinding of subjects was possible, was it reported? 8 outcome and (if applicable) exposure measure(s) well defined and robust to measurement / misclassification bias? means of assessment reported? 9 sample size appropriate? 10 analytic methods described/justified and appropriate? 11 some estimate of variance is reported for the main results? 12 controlled for confounding? 13 results reported in sufficient detail? 14 conclusions supported by the results? table b.2 (reference 340): ranking criteria for scores generated using the qualsyst quality assessment tool. the tool consists of a quantitative study checklist with 14 criteria. each criterion can be scored 0, 1, or 2 points provided the study doesn’t, partially does, or does meet the criteria respectively. thus, the greater the score the higher the quality of evidence. study type maximum possible score quality threshold scores percentage (%) of maximum possible score quality quantitative 28 < 50% limited ≥ 50% and < 70% adequate ≥ 70% and < 80% good ≥ 80% strong a p p e n d ix https://doi.org/10.33137/cpoj.v7i2.43715 32 williams-reid h, johannesson a, buis a. wound management, healing, and early prosthetic rehabilitation: part 1 a scoping review of healing and non-healing definitions. canadian prosthetics & orthotics journal. 2024; volume 7, issue 2, no.1. https://doi.org/10.33137/cpoj.v7i2.43715 canadian prosthetics & orthotics journal issn: 2561-987x wound management: healing and non-healing definitions williams-reid et al., 2024 appendix c: table c.1 (reference 280): jbi levels of evidence for effectiveness. these levels are intended to be used alongside the supporting document outlining their use and using these levels does not preclude the need for careful reading, critical appraisal and clinical reasoning when applying evidence. levels of evidence effectiveness level 1 – experimental designs level 1.a – systematic review of randomized controlled trials (rcts) level 1.b – systematic review of rcts and other study designs level 1.c – rct level 1.d – pseudo-rcts level 2 – quasi-experimental designs level 2.a – systematic review of quasi-experimental studies level 2.b – systematic review of quasi-experimental and other lower study designs level 2.c – quasi-experimental prospectively controlled study level 2.d – pre-test – post-test or historic/retrospective control group study level 3 – observational – analytic designs level 3.a – systematic review of comparable cohort studies level 3.b – systematic review of comparable cohort and other lower study designs level 3.c – cohort study with control group level 3.d – case-controlled study level 3.e – observational study without a control group level 4 – observational descriptive studies level 4.a – systematic review of descriptive studies level 4.b – cross-sectional study level 4.c – case series level 4.d – case study level 5 – expert opinion and bench research level 5.a – systematic review of expert opinion level 5.b – expert consensus level 5.c – bench research/single expert opinion table c.2 levels of evidence diagnosis level 1 – studies of test accuracy among consecutive patients level 1.a – systematic review of studies of test accuracy among consecutive patients level 1.b – study of test accuracy among consecutive patients level 2 – studies of test accuracy among nonconsecutive patients level 2.a – systematic review of studies of test accuracy among non-consecutive patients level 2.b – study of test accuracy among non-consecutive patients level 3 – diagnostic case control studies level 3.a – systematic review of diagnostic case control studies level 3.b – diagnostic case-control study level 4 – diagnostic yield studies level 4.a – systematic review of diagnostic yield studies level 4.b – individual diagnostic yield study level 5 – expert opinion and bench research level 5.a – systematic review of expert opinion level 5.b – expert consensus level 5.c – bench research/single expert opinion table c.3 levels of evidence prognosis level 1 – inception cohort studies level 1.a – systematic review of inception cohort studies level 1.b – inception cohort study level 2 – studies of all or none level 2.a – systematic review of all or none studies level 2.b – all or none studies level 3 – cohort studies level 3.a – systematic review of cohort studies (or control arm of rct) level 3.b – cohort study (or control arm of rct) level 4 – case series/case controlled/ historically controlled studies level 4.a – systematic review of case series/case controlled/historically controlled studies level 4.b – individual case series/case controlled/historically controlled study level 5 – expert opinion and bench research level 5.a – systematic review of expert opinion level 5.b – expert consensus level 5.c – bench research/single expert opinion table c.4 levels of evidence – economic evaluations level 1 decision model with assumptions and variables informed by systematic review and tailored to fit the decision-making context. level 2 systematic review of economic evaluations conducted in a setting similar to the decision makers. level 3 synthesis/review of economic evaluations undertaken in a setting similar to that in which the decision is to be made and which are of high quality (comprehensive and credible measurement of costs and health outcomes, sufficient time period covered, discounting, and sensitivity testing). level 4 economic evaluation of high quality (comprehensive and credible measurement of costs and health outcomes, sufficient time period covered, discounting and sensitivity testing) and conducted in setting similar to the decision-making context. level 5 synthesis/review of economic evaluations of moderate and/or poor quality (insufficient coverage of costs and health effects, no discounting, no sensitivity testing, time period covered insufficient). level 6 single economic evaluation of moderate or poor quality (see directly above level 5 description of studies). level 7 expert opinion on incremental cost effectives of intervention and comparator. table c.5 levels of evidence meaningfulness level 1 qualitative or mixed-methods systematic review level 2 qualitative or mixed-methods synthesis level 3 single qualitative study level 4 systematic review of expert opinion level 5 expert opinion a p p e n d ix https://doi.org/10.33137/cpoj.v7i2.43715 all articles are permanently available online to the public without restrictions or subscription fees. they are free to be used, cited, and distributed, provided that appropriate acknowledgment is included. authors retain the copyright of their original contributions and grant the canadian online publication group (copg) a license to publish the article and identify itself as the original publisher. cpoj articles are licensed under the creative commons attribution 4.0 international license. cpoj website: https://jps.library.utoronto.ca/index.php/cpoj/index editorial office: cpoj@online-publication.com issn: 2561-987x cpoj is a member of, and subscribes to the principles of, the committee on publication ethics (cope). cpoj articles are freely accessible on pubmed central® (pmc). volume 8, issue 1 2025 research article eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 https://jps.library.utoronto.ca/index.php/cpoj/index mailto:cpoj@online-publication.com https://publicationethics.org/about/our-organisation https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal https://doi.org/10.33137/cpoj.v8i1.44720 https://pmc.ncbi.nlm.nih.gov/journals/?term=%22canadian+prosthetics+%26+orthotics+journal%22 1 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 research article glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward eshraghi a1*, safaeepour z 2 1. west park healthcare centre, university health network, toronto, canada. 2. department of human performance and health, university of south carolina upstate, spartanburg, south carolina, united states. introduction the glass ceiling metaphor is frequently used to describe the obstacles and barriers in front of women seeking promotions to the top levels of organizations.1-2 there is strong evidence of the under-representation of women in leadership positions in countries such as australia,3 china,4 france,5 and the united states.6 there is a strong need for ongoing investigations into the causes and consequences of glass ceilings, especially in corporate organizations. research on the glass ceiling shows that women may encounter obstacles in pursuing high-level management positions. hymowitz and schellhardt introduced the term glass ceiling in their 1986 wall street journal article.7 although they were the first to use the metaphor, they were not the first to write about the challenges women faced as they attempted their climb up the corporate ladder to senior-level positions. hymowitz and schellhardt remarked that even women who successfully climbed the corporate ladder would eventually crash into an invisible barrier. although high-level positions appeared to open access abstract background: the glass ceiling, a metaphorical barrier hindering women’s career advancement, is prevalent across various sectors, including healthcare. women have proved their competence as successful senior-level leaders. despite this, there is still a striking under-representation of female prosthetists and orthotists in leadership positions as managers and business owners. this study investigated the "glass ceiling" phenomenon in the prosthetics and orthotics (p&o) field, where women, despite growing representation in the profession, are underrepresented in leadership roles. objective: this study aimed to examine the beliefs and expectations of female prosthetists and orthotists regarding career advancement and leadership opportunities. methodology: this survey study had two sections; the first section was general demographic questions, and any gender could participate but the second section was the career pathways survey (cps), which assessed beliefs about the glass ceiling and only female practitioners could participate. the survey evaluated four factors: denial, resilience, acceptance, and resignation, to understand how women perceive their ability to break through the glass ceiling. all individuals with a professional qualification in prosthetics and/or orthotics were eligible to participate. the survey was distributed worldwide through the ispo and other professional associations. the survey was opened in april 2021 and remained active for six months. findings: 110 female participants completed the survey. the participants were mainly from north america, europe and australia. findings revealed that factors like age, marital status, and salary were significant predictors of different belief scores, particularly with respect to career acceptance and denial. results highlighted that women’s beliefs about their career advancement were influenced by their personal life situations, such as having children, and the number of years of professional experience. conclusion: the study calls for organizational reforms to address gender inequalities by implementing policies that support work-life balance, mentoring, and career development. it also emphasizes the importance of further research, particularly examining the intersectionality of gender, race, and other diversity factors, to provide a comprehensive understanding of barriers to leadership in p&o and other healthcare fields. article info received: february 10, 2025 accepted: may 12, 2025 published: june 17, 2025 citation eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj. v8i1.44720 keywords glass ceiling; prosthetics; orthotics; gender inequality; diversity; prosthetists; career advancement; leadership; women; gender; orthotists. * corresponding author: arezoo eshraghi, phd, cp(c) affiliation: west park healthcare centre, university health network, toronto, canada. e-mail: arezoo.eshraghi@uhn.ca orcid id: https://orcid.org/0000-0002-1525-8093 journal homepage: https://jps.library.utoronto.ca/index.php/cpoj/index volume 8, issue 1, article no. 6, 2025 https://doi.org/10.33137/cpoj.v8i1.44720 https://doi.org/10.33137/cpoj.v8i1.44720 https://doi.org/10.33137/cpoj.v8i1.44720 mailto:arezoo.eshraghi@uhn.ca https://orcid.org/0000-0002-6349-2992 https://jps.library.utoronto.ca/index.php/cpoj/index 2 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 be within women's reach, they could not crack the glass ceiling. since these remarks were made, others have continued the effort to better understand the antecedents of the phenomenon through research, which has led to the development of theories attempting to explain the phenomenon.7 prosthetics and orthotics are established disciplines in health science and are often practiced together as they have many commonalities from clinical, technical, and therapy perspectives. prosthetic and orthotic devices are usually part of the secondary/tertiary care, habilitation, and rehabilitation programs. the number of female prosthetists and orthotists has risen worldwide. in the united states only, according to the american orthotic & prosthetic association (aopa), in 2014, 20% of practitioners who had registered with the american board for certification in orthotics, prosthetics and pedorthics (abc) were women, a 748% increase since 1994; abc also estimates women and men now enter o&p in about a 1:1 ratio. among professional members of the american society for biomechanics (asb) who report their gender, 31% are women, as are 42% of student members (2016 data).8 women have proved their competence as successful senior-level leaders. despite this, there is still a striking under-representation of female prosthetists and orthotists in leadership positions as managers and business owners.9 it is unknown what female graduates expect from their future careers, and if those expectations are realistic, especially when it comes to managerial positions. also, it is not known what role cultural context plays in success expectations and professional promotions among females, and other nontraditional prosthetists and orthotists. research in other fields, such as medicine, banking, and sports management, emphasize gender differences as the major reason for gender inequality in leadership.10-13 the glass ceiling is supported by conscious and unconscious gender stereotypes and biases, a lack of policies that support work-life balance, a lack of mentors or role models for women interested in high-level career advancement, and a paucity of networks that can open doors to women. nothing is known about other diversity barriers in prosthetics and orthotics, such as age, place of origin or education, or language proficiency. the field is small and internationally connected. anecdotally, there is a sense that the location of education is a significant barrier to entering the field of prosthetics and orthotics. therefore, this study is the first to develop pilot information on women's beliefs about glass ceilings among female prosthetists and orthotists. methodology ethics approval was obtained from the british columbia institute of technology (bcit) research ethics board (202105). the first part of this survey study measured the demographics: age, marital status, number of children, years of work experience in p&o, qualification, and country of work (table 1). both male and females participants could fill in this part. the second part involved the career pathways survey (cps) adopted from smith et al.14,15 this part was only asked to be answered by female participants. the cps is a multi-factorial instrument which quantitatively assesses four sets of beliefs about glass ceilings: denial, resilience, acceptance, and resignation. the cps provides scores for four groups of beliefs about glass ceilings. • denial: denial is defined as the belief that men and women face the same issues and problems in seeking leadership. examples of items in the cps assessing denial are: “women have reached the top in all areas of business and politics”, and “women starting careers today will face sexist barriers” (reverse scored). • resilience: resilience is defined as the belief that women are able to break glass ceilings. examples of this factor are: “the more women seek senior positions, the easier it will be for those who follow”, and “women are capable of making critical leadership decisions”. • acceptance: acceptance is the belief that women prefer other life goals, such as family involvement, over developing a career. therefore, acceptance is summed up as a pro-family/anti-career advancement set of beliefs. examples of items in the cps assessing acceptance are: “women reject the need to work incredibly long hours”, and “women are less concerned about promotions than men are”.15 • resignation: resignation is the belief that women suffer many more negative consequences than men when pursuing career advancement and thus, there are overwhelming reasons for women not attempting to break glass ceilings. two cps items measuring this factor are: “women are more likely to be hurt than men when they take big risks necessary for corporate success”, and “jealousy from coworkers prevents women from seeking promotions”. the 38 items of the cps represent beliefs about a wide variety of variables that considerable research has shown to be linked to women's career advancement.7,16 for example, the cps items refer to issues such as role models, lack of promotion opportunities for women, sexist barriers in organizations, successful organizations wanting talented women leaders, work-family compromises, benefits of higher education, networking, jealousy from female colleagues after promotions, support from mentors, and sexual harassment. participants rated their level of agreement with 38 statements on a scale from 1 (strongly disagree) to 7 (strongly agree). individual factor scores are calculated by the mean score of the relevant items. https://doi.org/10.33137/cpoj.v8i1.44720 3 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 data collection all individuals (male and female) with a professional qualification in prosthetics and/or orthotics that was valid in the region in which they worked were eligible to participate in the survey. subjects were recruited by posting on the oandp list-serve and distribution of an invitation to participate by the orthotics prosthetics canada (opc), british association of prosthetists & orthotists (bapo), american orthotic & prosthetic association (aopa), and international society for prosthetics and orthotics (ispo). moreover, persons receiving the invitation were asked to forward the invitation to prosthetists and orthotists in their networks (snowball sampling method). the link in the invitation directed interested persons to an explanatory letter with information on the study purpose, inclusion criteria, confidentiality, risk, and consent, along with a link to a surveymonkey that enabled the anonymous submission of responses to the questionnaire (appendix a and b). statistical analysis statistical analyses were performed using sas 9.4m7 (sas institute, cary, north carolina). one-way analysis of variance (anova) was used to test for differences in mean scale response variables (denial, resilience, acceptance, and resignation) between levels of categorical demographic variables. a separate one-way anova was conducted for each of these scale responses. post hoc tests using a tukey-kramer adjustment were performed to locate differences in mean responses between pairs of levels of demographic variables. the standard model assumptions regarding the residuals were verified. the residuals were approximately normally distributed random variables centered about zero with constant variance. in cases where outliers were detected, the analysis was re-run removing the outlier, but none of the final model conclusions changed, so the outliers remained in the model. sample size was determined using gpower, with an expected effect size of 0.8, alpha level of 0.05, and power of 95%. results 110 female participants completed the survey. the survey was opened in april 2021 and remained active for six months. some participants did not answer all the questions and therefore were not included in the data analysis to avoid potential issues with model estimation. the participants were mainly from north america (n = 56), europe (n = 18) and australia (n = 21) followed by asia (n = 9) and africa (n = 6). table 1 shows the summary statistics for each set of beliefs broken down by each level of the demographic variable. the responses from asia and africa were excluded from the analysis due to the number of participants needed for model estimation. the one-way anova revealed a statistically significant difference in mean denial scores between age groups (f2,107 = 3.21, p = 0.04). a post-hoc tukey-kramer test for multiple comparisons found that the mean value of denial scores was statistically significantly (p-value = 0.03) higher in the 46+ age group (mean = 38.3) than in the 18-35 age group (mean = 29.3). table 2 represents results of one-way analysis of variance (anova) for differences in mean scale response variables (denial, resilience, acceptance, and resignation) between levels of categorical demographic variables. table 1: summary statistics of four sets of beliefs about the glass ceiling based on the career pathway survey. factors denial mean (sd) resilience mean (sd) resignation mean (sd) acceptance mean (sd) age (year) 18-35 29.3 (11.5)a 40.0 (14.4) 55.5 (6.6) 23.2 (6.9) 36-45 33.0 (12.93) 36.5 (10.7) 56.3 (7.1) 24.9 (5.5) 46+ 38.3 (14.3)a 35.2 (13.0) 55.6 (12.6) 26.6 (7.02) marital status married 33.6 (13.4) 36.9 (12.2) 56.5 (8.5) 24.8 (6.5) single 29.5 (11.5) 40.0 (14.6) 54.7 (7.3) 23.7 (6.7) number of children none 29.1 (11.3)b 39.3 (14.0) 54.3 (8.9) 22.4 (6.1) at least one child 34.6 (13.6)b 36.0 (11.9) 56.8 (7.6) 25.7 (6.1) years of experience 0-5 29.2 (11.6) 39.9 (15.0) 54.6 (7.4) 22.3 (7.7) 6-10 29.4 (11.1) 39.9 (13.8) 56.0 (5.01) 25.3 (5.5) 11-15 35.7 (13.7) 35.2 (11.4) 56.5 (7.7) 23.6 (5.8) 16-25 31.4 (13.2) 39.7 (11.1) 55.6 (11.5) 26.1 (6.7) >26 40.0 (14.0) 31.6 (11.8) 57.1 (9.5) 26.4 (5.7) country of work europe 30.4 (7.4) 41.9 (9.1) 56.2 (6.3) 24.1 (6.4) australia 30.3 (10.1) 34.9 (12.4) 54.5 (7.6) 24.0 (5.4) north america 31.7 (13.8) 37.3 (14.1) 55.5 (9.0) 24.0 (6.9) qualification 1-4 semesters 34.2 (14.0) 36.6 (13.5) 56.9 (7.9) 25.3 (6.2) bachelor 33.7 (10.6) 40.9 (11.6) 55.5 (9.0) 25.0 (6.3) master 28.1 (14.9) 35.8 (13.3) 55.5 (6.9) 21.3 (6.7) a shows a statistically significant difference in mean denial scores between age groups, 18-35 and 46+ at the 0.05 level of significance. b shows a statistically significant difference in mean denial scores between the number of children groups, no children and at least one child at the 0.05 level of significance. https://doi.org/10.33137/cpoj.v8i1.44720 https://opcanada.ca/ https://www.bapo.com/ https://www.aopanet.org/ https://www.ispoint.org/ 4 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 table 2: one-way analysis of variance (anova) for differences in mean scale response variables (denial, resilience, acceptance, and resignation). pearson correlation coefficients prob > |r| under h0: rho=0 number of observations denial resignation resilience acceptance denial 1.00 -0.41 0.01 0.24 <.0001 0.95 0.02 99.00 99.00 97.00 96.00 resignation -0.41 1.00 -0.07 0.16 <.0001 0.49 0.11 99.00 99.00 97.00 96.00 resilience 0.01 -0.07 1.00 0.08 0.95 0.49 0.43 97.00 97.00 97.00 96.00 acceptance 0.24 0.16 0.08 1.00 0.02 0.11 0.43 96.00 96.00 96.00 96.00 the one-way anova revealed a statistically significant difference in mean denial scores between the number of children groups (f1,88 = 4.47, p = 0.04). a post hoc tukeykramer test found that the mean value of denial scores was statistically significantly (p-value = 0.04) higher in participants with one child (mean = 34.6) compared to those with no children (mean = 29.1). a borderline statistically significant difference was seen in mean acceptance scores between academic qualification groups (f2,87 = 2.87 p = 0.06). the mean acceptance scores were higher for employees with 1-4 semesters of education (mean = 34.2) compared to employees with master’s degrees (mean = 28.1). the type iii tests of fixed effects from a multiple regression model in table 3 show that salary is a statistically significant predictor of mean denial scores with p-values of 0.02. table 3 shows there is a statistically significant difference (pvalue = 0.02) in mean denial scores between subjects with salary >40k (mean = 34.6) and salary <40k (mean = 27.3). resilience was predicted by both salary >40k and having no children. resilience scores were significantly higher for people with salary >40k compared to salary <40k (f1, 92 = 5.6, p = 0.02). the lack of children in an individual’s demographic category significantly predicted increased resilience scores (f1, 92 = 3.7, p = 0.04). table 3: results of multiple regression model. a weak positive correlation was detected between number of children and denial (r = 0.27, p < 0.01) and resilience scores (r = 0.23, p-value = 0.02) (table 4). table 4: results of pearson correlation for number of children and hours of work in relation to four sets of beliefs about glass ceilings. pearson correlation coefficients prob > |r| under h0: rho=0 number of observations denial resignation resilience acceptance number of children 0.27 -0.16 0.23 0.15 0.01 0.11 0.02 0.14 100.00 100.00 98.00 hours work in week 0.10 0.00 0.04 -0.13 0.32 0.99 0.71 0.17 109.00 109.00 107.00 106.00 discussion this study investigated the perceptions and beliefs of female prosthetists and orthotists regarding the glass ceiling and professional advancement. the findings indicate a complex interplay of factors that contribute to barriers in career progression for women in the field, including gender, family status, and educational background. these results are consistent with studies in other fields that have found that women often encounter significant obstacles in advancing to senior leadership positions.2 similar to other professions, the findings of this study is an empirical evidence that the glass ceiling phenomenon still exists for female prosthetists & orthotists.17-19 one major finding was the difference in denial scores among age groups, with older participants exhibiting more denial about the existence of gender-based barriers than younger participants. this suggests that, over time, women may become more aware of the glass ceiling or, conversely, become more accepting of its limitations as they progress in their careers. furthermore, the study showed that women with one child were more likely to deny the existence of gender-based barriers compared to those without children. this might be due to the demands of balancing career and family life, which may lead to a pragmatic acceptance of organizational limitations.20 in contrast, women without children were found to have higher resilience scores, which may reflect fewer family-related barriers to professional advancement. this is consistent with the finding that women with fewer family commitments are better able to dedicate time and energy to career advancement.17 in some professions, it is possible to work from home, which provides an opportunity to take care of children.21 this is barely possible for orthotist & prosthetist clinician and technicians due to responsibilities of direct in-person patient care and manufacturing requirements that should be done in a prosthetic and orthotic workshop. educational background also played a significant role in the beliefs about glass ceilings. participants with lower levels of education (1-4 semesters) reported higher acceptance of the idea that women prefer family life over career advancement. this suggests that education, especially higher education, may increase awareness of career opportunities and career advancement processes. df type iii ss mean square f value pr > f salary 1 567.33 567.33 5.56 0.02 education cat 2 396.63 198.31 1.94 0.16 age 2 46.92 23.46 0.23 0.80 country of work 2 222.23 111.12 1.09 0.35 years of experience 4 531.57 132.89 1.30 0.29 number of children 1 166.17 166.17 1.63 0.20 https://doi.org/10.33137/cpoj.v8i1.44720 5 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 salary was also identified as a significant predictor of denial, with individuals earning more than $40,000 reporting higher denial scores. this suggests that higher earnings may lead to a greater sense of professional success and thus reduce the perceived impact of gender-related barriers to career advancement. these findings are valuable for understanding the factors that contribute to the under-representation of women in leadership roles within prosthetics and orthotics, as they point to a combination of personal, professional, and cultural influences that impact career progression. furthermore, they underscore the importance of developing policies and programs that support work-life balance, professional development, and mentorship to help break the glass ceiling in this field.15,22 limitations to our knowledge, there is no other similar research work done and published on this topic in p&o so we couldn’t make comparisons across the literature. our initial intention was to do sampling worldwide but during the time that survey was active, we got mainly participants from north america, europe and australia, while only few from other regions so we could not include those participants in the data analysis. the literature shows that glass ceiling may be experienced more in lowand middle-income countries; therefore, the future study will seek sampling methods that would increase participation from those areas. in this study, we only asked female clinicians to answer the glass ceiling survey while it is worthwhile to know how male clinicians perceive the glass ceiling. both males and females may experience glass ceilings and therefore we will consider including both genders in the study in future study. another limitation was that not all the participants answered every section and/or question on the survey, which made it difficult to come to conclusions or study the relationship between all variables. conclusion since the latter half of the 20th century, women have made great strides in increasing their representation in the work force. however, a considerable gap remains in achievement of leadership positions across fields such as healthcare. thus, the bewildering glass ceiling remains intact and, at times, seemingly invulnerable. we propose that glass ceiling beliefs can lift or diminish desires to be promoted. these beliefs may lead to career pathway choices and longlasting behaviors within organizations. women who express an ambition to become part of upper management, could gain insights by analyzing their levels of resilience and denial. high acceptance scores could help identify women with little or no ambition to be promoted, yet would benefit from professional development whilst maintaining their level in the organization. finally, feedback from cps testing might also facilitate women gaining greater awareness of the possible causes for their subjective success in organizations. those women who score high on resignation could benefit from training and development courses that help them examine the validity of their negative thoughts about women seeking promotions. however, if it is found that an organization's structure and actions do indeed lead to resignation, major changes will be needed before women in that organization can dismiss their negative beliefs. acknowledgements the authors wish to thank dr. silvia raschke for consultation on this study from the design to conduct and knowledge translation. we extend our gratitude to dr. nancy paris and the bcit make+ department for funding the statistical analysis and for the administrative support. special thanks to mr. ian bercovitz, director of statistical consulting, department of statistics and actuarial science, simon fraser university, for his thorough work on the data analysis. declaration of conflicting interests the authors report no conflict of interest. authors contribution • arezoo eshraghi: conceptualization, ethics application, methodology, data collection and analysis, writing/revising the manuscript, final manuscript approval. • zahra safaeepour: conceptualization, ethics application, 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s, yoon b. the role of glass ceiling perception on work engagement and service orientation behavior among female hotel employees. j hum resour hosp tour. 2021; 20(4):497-511. doi: 10.1080/15332845.2021.1959799 19.javadizadeh b, ross j, valenzuela ma, adler tr, wu b. what’s the point in even trying? women’s perception of glass ceiling drains hope. j soc psychol. 2024;164(4):488-510. doi: 10.1080/00224545.2022.2119121 20.naseviciute l, juceviciene r. overcoming the barriers to women's career in information and communication technology business. equal divers incl. 2024;43(1):23-40. doi: 10.1108/edi09-2022-0265 21.taparia m, lenka u. an integrated conceptual framework of the glass ceiling effect. organ eff-people p. 2022;9(3):372-400. doi: 10.1108/joepp-06-2020-0098 22.smith p, caputi p, crittenden n. how are women's glass ceiling beliefs related to career success? career dev int. 2012;17(5):458– 74. doi:10.1108/13620431211269702 https://doi.org/10.33137/cpoj.v8i1.44720 https://lermagazine.com/cover_story/womens-work-overcoming-gender-barriers-in-lower-extremity-specialties https://lermagazine.com/cover_story/womens-work-overcoming-gender-barriers-in-lower-extremity-specialties https://livingwithamplitude.com/article/women-prosthetists-are-making-an-impact-on-amputee-care/ https://livingwithamplitude.com/article/women-prosthetists-are-making-an-impact-on-amputee-care/ 7 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 a p p e n d ix appendix appendix a explanatory letter with survey (february 2, 2021) baseline survey: glass ceilings in prosthetics & orthotics: perceptions, opportunities and strategies for moving forward principle investigator: silvia raschke, phd, bcit make+ tel: 604-412-7597 e-mail: silvia_raschke@bcit.ca co-investigator: zahra safaeepour, phd university of south carolina upstate. co-investigator: arezoo eshraghi, phd, cp (c) west park healthcare centre. the purpose of this project is to examine perceptions and beliefs that contribute to the glass ceiling effect for persons choosing a career in prosthetics and orthotics. factors such as gender, age and career aspirations will be explored. there will be no compensation provided for participating in the survey. this study will provide baseline survey data to take an objective snapshot of the prosthetics and orthotics profession in 2021. the researchers intend to apply for grant funding to explore this topic more deeply with the goal of developing strategies, recommendations and tools for engaging and recruiting persons not traditionally considering prosthetics and orthotics as a career, with a focus on females. results will also be presented at a conference(s) and will be submitted for publication in a peer-reviewed journal. the survey consists of two parts: • part a is for all participants and should take between 10 and 15 minutes to complete. part b is an additional set of questions for all participants identifying as female and will take approximately 15 additional minutes to complete. the survey is open to all persons who hold a recognized international qualification in prosthetics and/or orthotics (e.g bachelor’s degree, certification, licensure, meister, etc.) and who have reading and writing comprehension in english it is not necessary for you to be qualified to practice in your country of residence. to keep your identity confidential, no personally identifiable information will be collected or stored during this research project (i.e. you will not be identifiable in any reports, publications or presentations resulting from this study). all data and comments will be collapsed into a summary document. please note that researchers may be required to make the survey data publicly available at the time of publication. you should be aware that once data is made publicly available you will not be able to withdraw any comments. if, at any time during the survey you wish to withdraw from the survey you can do so at any point by simply closing the browser. there is minimal anticipated risk to participating in this survey. if you would like to have a summary of the results of the survey or if you have any questions, or concerns, regarding this survey or your participation you can email me directly at: silvia_raschke@bcit. if there are any further concerns you may contact the research ethics board at research_ethics@bcit.ca. https://doi.org/10.33137/cpoj.v8i1.44720 mailto:silvia_raschke@bcit.ca 8 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 a p p e n d ix appendix b survey questions project: baseline survey: glass ceilings in prosthetics & orthotics: perceptions, opportunities and strategies for moving forward part a survey questions (for all respondents) professional history 1highest level of general education (check one): _____apprenticeship _____1 to 2 semester certificate _____2 to 4 semester diploma/certificate _____bachelor’s degree _____master’s degree _____phd _____other: (please specify) ____________________ 2country in which you received your highest level of education: ________ 3country(ies) in which you received your prosthetics and orthotics education: note: if you have more than one certification and/or degree please note each completed certificate/diploma and/or degree and, in brackets next to it, note the country in which it was obtained. (e.g. master’s degree (uk)) 4highest level of prosthetics and orthotics specific education: check one: _____apprenticeship _____1 to 2 semester certificate _____2 to 4 semester diploma/certificate _____bachelor’s degree _____master’s degree _____phd _____other: (please specify) ____________________ 5country in which you work : _________________ 6country in which you live/are a resident of: _______________ 7if you are seeking work in a country different from where you currently work and/or live, what is the country in which you are seeking work: 8professional qualification(s) held in prosthetics and orthotics (over and above general education degree): (choose all that apply) ______certified orthotist, ______certified prosthetist, ______licensed orthotist, ______licensed prosthetist, ______certified prosthetist orthotist, ______ meister . ______registered prosthetic technician, ______registered orthotic technician ______other (please specify): 9is this qualification required for you to work in the country of your education? _____ yes_____ no 10is this qualification required for you to work in your country of residence?_____ yes _____ no 11is this qualification recognized in the country in which you are aspiring to work in? _____ yes _____ no _____ not applicable 12 – how many years have you worked in the field of prosthetics and orthotics? ________ 13 what is your current employment status in the field of prosthetics and orthotics? ____employed full-time ____employed part-time ____self-employed ____unemployed, seeking opportunities ____unemployed, not seeking opportunities ____retired ____other: _________ 14 – how many hours per week are you currently working in the field of prosthetics and orthotics? _____ 15 would having the ability to have a permanent part-time position be of interest to you at any point in your career? (yes/no) 16 have you ever sought a permanent part-time position at any point in your career? (yes/no) 17 if yes, were you able to find a permanent part-time position? (yes/no) 1. first certificate/diploma/degree (country obtained) 2. second certificate/diploma/degree (country obtained) 3. third certificate/diploma/degree (country obtained) 4. fourth certificate/diploma/degree (country obtained) https://doi.org/10.33137/cpoj.v8i1.44720 9 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 a p p e n d ix general exploratory survey 18 this question asks you to consider your personal professional aspirations as a prosthetics and orthotics practitioner. e.g. my ultimate career goal is to: * • be a dual qualified prosthetist orthotist • be leading prosthetic and orthotic research • be working in a public hospital or clinic • own my own prosthetics/orthotics business • be managing a hospital department • be working for a private practice • be working clinically part time and will spend the remainder of my time doing (x) . • be carrying out prosthetic and orthotic research • other ___________________ *note: the examples given above have been randomized (other than the last item ‘other’) in order to mitigate order bias. in each box below, identify up to 3 professional aspirations you hope to achieve in the field of prosthetics and orthotics field (max. 30 words, 10 per box) 19 what is the highest professional level you anticipate you will have achieved in your career as a certified prosthetics/orthotics practitioner? (pick one)* ____ employee ____ researcher ____ will have left the profession ____ manager ____ business owner ____ other: ___________________________(please provide details) *note: the examples given above have been randomized (other than the last item ‘other’) in order to mitigate order bias 20 in the region where you live what is the most common business model in p&o? (pick one)* ______ private clinic with multiple employees ______ prosthetic and orthotic services are provided by a non governmental organization (ngo) ______ public service hospital/clinic ______ small family businesses ______ other ___________________________(please describe on line provided) *note: the examples given above have been randomized (other than the last item ‘other’) in order to mitigate order bias 21 in the region where you live what is the second most common business model in p&o? (pick one)* ______ prosthetic and orthotic services are provided by a non governmental organization (ngo) ______ small family businesses ______ private clinic with multiple employees ______ public service hospital/clinic ______ other ___________________________(please describe on line provided) *note: the examples given above have been randomized (other than the last item ‘other’) in order to mitigate order bias 22 describe what success in your chosen career of prosthetics and orthotics looks like for you. (max. 100 words) 23 do you see any barriers to your achieving personal success in prosthetics and orthotics, as you have described above? _ yes_ no if yes, please list those barriers in the box below (max 25 words). 24 describe what the glass ceiling looks like in prosthetics and orthotics, from your perspective, even if you have not experienced it. if you do not believe a glass ceiling exists, please note that. 1 2 3 next we will explore what a glass ceiling looks like in the fields of prosthetics and orthotics. a glass ceiling is described as: “invisible artificial barriers (sometimes generated by management) that can limit the career advancement of employees, particularly women and members of minority groups. the expectations and aspirations of all staff within an organization should be met equally. while standards of practice in this area are laid down by law in many countries, they are not always observed.” from: oxford reference: https://www.oxfordreference.com/view/10.1093/oi/authority.20110803095854441 for the purpose of this general exploratory survey component, this question applies to all persons who could experience ‘invisible artificial barriers that limited <their> career advancement” for any range of reasons that include but are not limited to: gender, age, country of origin or education. https://doi.org/10.33137/cpoj.v8i1.44720 https://www.oxfordreference.com/view/10.1093/oi/authority.20110803095854441 10 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 a p p e n d ix 25 have you ever experienced a glass ceiling effect in the course of your career?__ yes __ no 26 if yes, describe your glass ceiling experience in the box below. (max. 150 words) 27 which identifying factor do you believe was the root of your experience with the glass ceiling described above?* check all that apply: _____ race _____ age _____ disability _____ gender _____ country of education _____ cultural background _____ language _____ religion _____ country of origin _____ other __________________________(describe) *note: the examples given above have been randomized (other than the last item ‘other’) in order to mitigate order bias 28 if you trained in a country different from the one you now live and subsequently sought employment in prosthetics and orthotics, did you face any barriers on the path to employment in prosthetics and orthotics in the country in which you now live/work in? _ yes _ no 29 if yes, please list up those barriers in the box below (max 40 words) i.e.g. * difficulty in: finding work, having a credential recognized, adapting to clinical and technical practices in country you are now working in, adapting to workplace culture, language difficulties, etc. *note: the examples given above have been randomized (other than the last item ‘other’) in order to mitigate order bias 2demographic details 30 what is your age? _____18-25 _____26-35 _____36-45 _____46-55 _____56-65 _____65+ 31country of birth: (pull down menu) 32which of the following best represents your racial and/or heritage? (non-mandatory question) choose all that apply. ___hispanic or latino ___east asian ___white or caucasian ___middle eastern ___native hawaiian or pacific islander ___mixed ___south asian ___asian ___first nations or indigenous ___black or african ___other preferred identifier: _____________ please print your specific ethnicities in the space below, if you wish. (examples of ethnicities include (for example): german, korean, mexican american, navajo nation, samoan, puerto rican, southerner (american), chinese, etc. note, you may report more than one group.) ethnicity(s) _________________________________ *note: the above have been randomized (other than the last two items) in order to mitigate order bias. **note: there are numerous potential lists that could be used for this question. we have used a list that combines what is used by researchers in us veteran’s association research applications and holland bloorview hospital (toronto). we anticipate most respondents will come from us/us territories and canada so the categories will be familiar to them. in addition the simplicity of this list will be understandable to persons from outside this geographic area who may also answer (through posting/distribution via the international society for prosthetics and orthotics network). https://doi.org/10.33137/cpoj.v8i1.44720 11 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 a p p e n d ix 33marital status: ___single (never married) ___married, or in a domestic partnership ___widowed ___divorced ___separated 34number of children: ______ 35the gender you identify as is:* ____female ____male ____other (provide gender identity, if you wish, in the space provided): ___________ *note: the examples given above have been randomized (other than the last item ‘other’) in order to mitigate order bias note: only persons choosing the female option above will proceed to part b. all others will be send to a page with the submit button. the follow reminder will placed above the submit button: clicking on the submit button below will submit your data to the survey, after which it can no longer be retrieved or changed. if you wish to withdraw from the study, you can still do so at this point by simply closing the browser. after clicking the submit button they will be taken to a page thanking them for participating them in the survey. part b survey questions (for respondents identifying as female) career pathways survey please consider each of the statements below and rank them from 1 (strongly disagree) to 7 (strongly agree) women starting careers today will face sexist barriers. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women and men have to overcome the same problems at the workplace. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 it will take decades for women to reach equality with men in high level management positions. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 even women with many skills and qualifications fail to be recognized for promotions. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women have reached the top in all areas of business and politics. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women face no barriers to promotions in most organizations. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women leaders are seldom given full credit for their successes. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women in senior positions face frequent putdowns of being too soft or too hard. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women who have a strong commitment to their careers can go right to the top. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 talented women are able to overcome sexist discrimination. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women executives are very uncomfortable when they have to criticize members of their teams. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women leaders suffer more emotional pain than men when there is a crisis within their teams. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 https://doi.org/10.33137/cpoj.v8i1.44720 12 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 a p p e n d ix being in the limelight creates many problems for women. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women are more likely to be hurt than men when they take big risks necessary for corporate success. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women believe they have to make too many compromises to gain highly paid positions. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 jealousy from co-workers prevents women from seeking promotions. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 even very successful women can quickly lose their confidence. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women know that work does not provide the best source of happiness in life. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 if women achieve promotions, they might be accused of offering sexual favours. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 smart women avoid careers that involve intense competition with colleagues. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 the more women seek senior positions, the easier it will be for those who follow. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 higher education qualifications will help women overcome discrimination. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women have the strength to overcome discrimination. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 when women are given opportunities to lead, they do effective jobs. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 daughters of successful mothers are inspired to overcome sexist hurdles. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women are capable of making critical leadership decisions. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 a supportive spouse/partner or close friend makes it easier for a woman to achieve success in her career. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 successful organizations seek and want to retain talented female staff. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 the support of a mentor greatly increases the success of a woman in any organization. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women's nurturing skills help them to be successful leaders. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 https://doi.org/10.33137/cpoj.v8i1.44720 13 eshraghi a, safaeepour z. glass ceiling among female prosthetists & orthotists: perceptions, opportunities and strategies for moving forward. canadian prosthetics & orthotics journal. 2025; volume 8, issue 1, no. 6. https://doi.org/10.33137/cpoj.v8i1.44720 canadian prosthetics & orthotics journal issn: 2561-987x glass ceiling among female prosthetists & orthotists eshraghi & safaeepour, 2025 a p p e n d ix networking is a smart way for women to increase the chances of career success. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women are just as ambitious in their careers as men. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women have the same desire for power as men do. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 motherhood is more important to most women than career development. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women are less concerned about promotions than men are. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women prefer a balanced life more than gaining highly paid careers. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women reject the need to work incredibly long hours. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 women commonly reject career advancement as they are keener to maintain a role raising children. (strongly disagree) (neutral) (strongly agree) 1 2 3 4 5 6 7 for those completing part b: on completion of part b the respondent will be taken to a submit button that looks the same as what the respondents who did part a only looks like: the follow reminder will placed above the submit button: clicking on the submit button below will submit your data to the survey, after which it can no longer be retrieved or changed. if you wish to withdraw from the study, you can still do so at this point by simply closing the browser. after clicking the submit button they will be taken to a page thanking them for participating them in the survey. https://doi.org/10.33137/cpoj.v8i1.44720 