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 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 medema a, henness d, steinhorst k, moauro r, reuland m, whelan r, kester s, bateni h. effect of level of amputation on postur al 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 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 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 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 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. 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 am ong 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 am ong 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 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. 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 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 dillingham t.r, kenia j, shofer f.s, marschalek j. an immediate fit and adjustable transtibial prosthetic system; a prospecti ve 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 prospecti ve 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. 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 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 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 balkman g, morgan s, gaunaurd i, kristal a, amtmann d, gailey r, hafner b.j. performance testing in people with lower limb am putation: 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 am putation: 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 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 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 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 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 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 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 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 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 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, 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 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 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 of life.48 references 1.winter da, patla ae, frank js, walt se. biomechanical walking pattern changes in the fit and healthy elderly. phys ther. 1990; 70, 340–347. 2.begg rk, tirosh o, said cm, sparrow wa, steinberg n, levinger p, galea mp. gait training with real-time augmented toe-ground clearance information decreases tripping risk in older adults and a person with chronic stroke. front hum neurosci. 2014;8:243. https://doi.org/10.3389/fnhum.2014.00243 3.mills pm, barrett rs. swing phase mechanics of healthy young and elderly men. hum mov sci. 2001; 20, 427–446. https://doi.org/10.1016/s0167-9457(01)00061-6 4.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, 493–501. https://doi.org/10.1016/j.gaitpost.2005.12.004 5.berg wp, alessio hm, mills em, tong c. circumstances and consequences of falls in independent communitydwelling older adults. age ageing. 1997; 26, 261–268. 6. li w, keegan th, sternfeld b, sidney s, quesenberry cp jr, kelsey jl. outdoor falls among middle-aged and older adults: a neglected public health problem. am j public health. 2006; 96, 1192–1200. doi: 10.2105/ajph.2005.083055 7.blake aj, morgan k, bendall mj, dallosso h, ebrahim sb, arie th, fentem ph, bassey ej. falls by elderly people at home: prevalence and associated factors. age ageing. 1988; 17, 365–372. 8.crenshaw jr, bernhardt ka, achenbach sj, atkinson ej, khosla s, kaufman kr, amin s. the circumstances, orientations, and impact locations of falls in communitydwelling older women. arch gerontol geriatr. 2017;73, 240–247. https://doi.org/10.1016/j.archger.2017.07.011 9.yang y, van schooten ks sims-gould j, mckay ha, feldman f, robinovitch sn. sex differences in the circumstances of falls among older adults in long-term care. innov aging. 2017; 431–432. https://doi.org/10.1093/geroni/igx004.1549 10.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, 422–429. https://doi.org/10.1016/j.apmr.2007.11.005 11.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, 1031–1037. doi:10.1053/apmr.2001.24295 12.knoche w. prothesen der unteren extremitat. die entwicklung vom altertum bis 1930. isbn:3-00-018655-7. 13.eshraghi a, osman naa, gholizadeh h, karimi m, ali s. pistoning assessment in lower limb prosthetic sockets. prosthet orthot int. 2012; 36, 15–24. https://doi.org/10.1177/0309364611431625 14.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, 21–26. 15. eshraghi a, osman naa, gholizadeh h, karimi m, soodmand e. gait biomechanics of individuals with transtibial amputation: effect of suspension system. plos one 9, e96988 (2014). https://doi.org/10.1371/journal.pone.0096988 16.erikson u, james u. roentgenological study of certain stump—socket relationships in above-knee amputees with special regard to tissue proportions, socket fit and attachment stability. ups j med sci. 1973;78, 203–214. 17.winter, d. a. foot trajectory in human gait: a precise and multifactorial motor control task. phys ther. 1992;72, 45–53. 18.gard sa, childress ds, uellendahl je. the influence of four-bar linkage knees on prosthetic swing-phase floor clearance. j prosthet orthot. 1996; 8, 34. https://doi.org/10.3389/fnhum.2014.00243 https://doi.org/10.1016/s0167-9457(01)00061-6 https://doi.org/10.1016/j.gaitpost.2005.12.004 https://doi.org/10.1016/j.archger.2017.07.011 https://doi.org/10.1093/geroni/igx004.1549 https://doi.org/10.1016/j.apmr.2007.11.005 https://doi.org/10.1053/apmr.2001.24295 https://doi.org/10.1177%2f0309364611431625 https://doi.org/10.1371/journal.pone.0096988 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 5 open access the importance of additional mid swing toe clearance for amputees volume 1, issue 2, article no.1, september 2018 19.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, 74–80. doi: 10.1109/tnsre.2012.2224885 20.friberg o. biomechanical significance of the correct length of lower limb prostheses: a clinical and radiological study. prosthet orthot int. 1984;8, 124–129. 21.gaunaurd i, gailey r, hafner bj, gomez-marin o, kirksanchez n. postural asymmetries in transfemoral amputees. prosthet orthot int. 2011; 35, 171–180. https://doi.org/10.1177/0309364611407676 22. 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 23.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, 15–29. 24.defrin r, benyamin sb, 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, 2075–2080. https://doi.org/10.1016/j.apmr.2005.06.012 25.mahar rk, kirby rl, macleod da. simulated leglength discrepancy: its effect on mean center-of-pressure position and postural sway. arch phys med rehabil.1985; 66, 822–824. 26.biering-sørensen f. physical measurements as risk indicators for low-back trouble over a one-year period. spine. 1984; 9, 106–119. 27.giles lgf, taylor jr. low-back pain associated with leg length inequality. spine. 1981;6, 510–521. 28.nolan l, wit a, dudziñski k, lees a, lake m, wychowañski m. adjustments in gait symmetry with walking speed in trans-femoral and trans-tibial amputees. gait posture. 2003; 17, 142–151. https://doi.org/10.1016/s0966-6362(02)00066-8 29.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, 274–279. 30.farrokhi s, mazzone b, yoder a, grant k, wyatt m. a narrative review of the prevalence and risk factors associated with development of knee osteoarthritis after traumatic unilateral lower limb amputation. mil med. 2016;181, 38–44. https://doi.org/10.7205/milmed-d-1500510 31. bohl aa, fishman pa, ciol ma, williams b, logerfo j, phelan ea. a longitudinal analysis of total 3-year healthcare costs for older adults who experience a fall requiring medical care. j am geriatr soc.2010; 58, 853– 860. https://doi.org/10.1111/j.1532-5415.2010.02816.x 32.kaufman, k. risk factors and costs associated with accidental falls among adults with above-knee amputations: a population-based study. american orthotic and prosthetic association 2016.(mayo clinic). http://www.aopanet.org/resources/research/ 33.mundell b, maradit kremers h, visscher s, hoppe k, kaufman k. direct medical costs of accidental falls for adults with transfemoral amputations. prosthet orthot int. 2017; 41, 564–570. https://doi.org/10.1177/0309364617704804 34.burns er, stevens ja, lee r. the direct costs of fatal and non-fatal falls among older adults — united states. j safety res. 2016; 58, 99–103. https://doi.org/10.1016/j.jsr.2016.05.001 35.march l, smith eu, hoy dg, cross mj, sanchez-riera l, blyth f, buchbinder r, vos t, woolf ad. burden of disability due to musculoskeletal (msk) disorders. best pract res clin rheumatol.2014; 28, 353–366. https://doi.org/10.1016/j.berh.2014.08.002 36.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, 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 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 altenburg b, ernst m, schmalz t. an innovative foot module with easily accessible frontal plane adaptation enhances the locom otion 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 locom otion 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 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 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 mileusnic m, rettinger l, highsmith m.j, hahn a. benefits of genium microprocessor controlled knee on ambulation, mobility, activities of daily livi ng 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 livi ng 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 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 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 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 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 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 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 war-related amputation. mil med. 2009;174(6):588-92. 4. ehde et al. chronic phantom sensations, phantom pain, residual limb pain, and other regional pain after lower limb amputation. arch phys med rehabil. 2000;81(8):1039-44. doi: https://doi.org/10.1053/apmr.2000.7583 5. mussman et al. contralateral lower extremity evaluation with a lower limb prosthesis. j am podiatry assoc. 1983 jul;73(7):344-6. 6. burke mj, roman v, wright v. bone and joint changes in lower limb amputees. ann rheum dis. 1978 jun; 37(3): 252– 254. 7. ebrahimzadeh mh, hariri s. long-term outcomes of unilateral transtibial amputations. mil med. 2009;174(6):593597. 8. ebrahimzadeh mh, fattahi as. long-term clinical outcomes of iranian veterans with unilateral transfemoral amputation. disabil rehabil. 2009;31(22):1873-7. doi:10.1080/09638280902810968 9. ehde et al. back pain as a secondary disability in persons with lower limb amputations. arch phys med rehabil. 2001;82(6):731-734. doi:10.1053/apmr.2001.21962 10. ephraim et al. phantom pain, residual limb pain, and back pain in amputees: results of a national survey. arch phys med rehabil.2005;86(10):1910-9. doi:10.1016/j.apmr.2005.03.031 11. friberg o. biomechanical significance of the correct length of lower limb prostheses: a clinical and radiological study. prosthet orthot int. 1984;8(3):124-9. 12. friel k, domholdt e, smith dg. physical and functional measures related to low back pain in individuals with lowerlimb amputation: an exploratory pilot study. j rehabil res dev. 2005;42(2):155-66. doi: 10.1682/jrrd.2004.08.0090 13. krämer j, heisel jm, ullrich ch. late results of patients with amputation of the thigh (author's transl). z orthop ihre grenzgeb. 1979;117(5):801-7. 14. kulkarni et al. chronic low back pain in traumatic lower limb amputees. clin rehabil. 2005 jan;19(1):81-6. doi:10.1191/0269215505cr819oa 15. kusljugić et al. chronic low back pain in individuals with lower-limb amputation. bosn j basic med sci. 2006 may;6(2):67-70. 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 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 il u 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 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. dickinson as, steer jw, woods cj, worsley p. registering methodology for imaging and analysis of residual-limb shape after transtibial amputation. journal of rehabilitation research and development.2016;53(2):207-18. doi: 10.1682/jrrd. 2014.10.0272. 3. saunders cg, foort j, bannon m, lean d, panych l. computer aided design of prosthetic sockets for belowknee amputees. prosthetics and orthotics international. 1985;9(1):17-22. doi: 10.3109/ 03093648509164819. 4. scott h, patel r, hebenton j. a survey of the lower limb amputee population in scotland 2010. publisher: glasgow [scotland]: national centre for training and education in prosthetics and orthotics, 2012. 5. radcliffe cw, foort j. the patellarr-tendon-bearing below-knee prosthesis. eberhart hd, inman vt, foort j, editors. berkeley: berkeley, biomechanics laboratory, dept. of engineering, university of california; 1961. 6. murdoch g. the "dundee" socket for the below-knee amputation. prosthetics and orthotics international. 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 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 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 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 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 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. 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 5. butowicz cm, dearth cl, hendershot bd. impact of traumatic lower extremity injuries beyond acute care: movement-based considerations for resultant longer term secondary health conditions. adv wound care (new rochelle). 2017;6(8):269-78. doi:10.1089/wound. 2016.0714 6. kuffler dp. origins of phantom limb pain. mol neurobiol. 2018;55(1):60-9. doi:10.1007/s12035-0170717-x https://doi.org/10.33137/cpoj.v2i1.31950 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.1016/j.apmr.2015.03.024 https://doi.org/10.1016/j.apmr.2015.03.024 https://link.springer.com/article/10.17269%2fcjph.108.6093 https://link.springer.com/article/10.17269%2fcjph.108.6093 http://canjsurg.ca/vol59-issue2/59-2-99/ https://doi.org/10.1016/j.apmr.2007.11.005 https://doi.org/10.1016/j.apmr.2007.11.005 https://doi.org/10.1089/wound.2016.0714 https://doi.org/10.1089/wound.2016.0714 https://doi.org/10.1007/s12035-017-0717-x https://doi.org/10.1007/s12035-017-0717-x 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 8 open access dysvascular lower extremity amputation volume 2, issue 1, article no.1, february 2019 https://jps.library.utoronto.ca/index.php/cpoj/index 7. matsumoto me, khan m, jayabalan p, ziebarth j, munin mc. heterotopic ossification in civilians with lower limb amputations. arch phys med rehabil. 2014;95(9): 1710-3. doi:10.1016/j.apmr.2014.03.010 8. pedras s, carvalho r, pereira mg. a predictive model of anxiety and depression symptoms after a lower limb amputation. disabil health j. 2018;11(1):79-85. doi: 10.1016/ j.dhjo.2017.03.013 9. padovani mt, martins mr, venancio a, forni je. anxiety, depression and quality of life in individuals with phantom limb pain. acta ortop bras. 2015;23(2):107-10. doi:10.1590/1413-78522015230200990 10. beekman ce, axtell la. prosthetic use in elderly patients with dysvascular above-knee and through-knee amputations. phys ther. 1987;67(10):1510-6. 11. lim ts, finlayson a, thorpe jm, sieunarine k, mwipatayi bp, brady a, et al. outcomes of a contemporary amputation series. anz j surg. 2006;76(5):300-5. doi:10.1111/j.1445-2197.2006.03715.x 12. 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):448-51. 13. lucke c, beindorff n, roy t, hoy l. rehabilitation of lower extremity amputation due to peripheral arterial occlusive disease inpatients with end-stage renal failure. vasc endovascular surg. 1999;33(1):33-41.https://doi.org/ 10.1177/153857449903300107 14. bhangu s, devlin m, pauley t. outcomes of individuals with transfemoral and contralateral transtibial amputation due to dysvascular etiologies. prosthet orthot int. 2009;33(1):33-40. doi:10.1080/03093640802492434 15. pohjolainen t, alaranta h, wikstrom j. primary survival and prosthetic fitting of lower limb amputees. prosthet orthot int. 1989;13(2):63-9. doi:10.3109/ 03093648909078214 16. fletcher dd, andrews kl, hallett jw, jr., butters ma, rowland cm, jacobsen sj. trends in rehabilitation after amputation for geriatric patients with vascular disease: implications for future health resource allocation. arch phys med rehabil. 2002;83(10):1389-93. https://doi.org/ 10.1053/ apmr.2002.34605 17. chen l, magliano dj, zimmet pz. the worldwide epidemiology of type 2 diabetes mellitus--present and future perspectives. nat rev endocrinol. 2011;8(4):22836. doi:10.1038/nrendo.2011.183 18. weisman a, fazli gs, johns a, booth gl. evolving trends in the epidemiology, risk factors, and prevention of type 2 diabetes: a review. can j cardiol. 2018;34(5): 552-64. doi:10.1016/j.cjca.2018.03.002 19. liu jj, liu s, gurung rl, ang k, tang we, sum cf, et al. risk of progressive chronic kidney disease in individuals with early-onset type 2 diabetes: a prospective cohort study. nephrol dial transplant. epub 2018 jun 6. https://doi.org/10.1093/ndt/gfy211 20. geiss ls, li y, hora i, albright a, rolka d, gregg ew. resurgence of diabetes-related nontraumatic lower extremity amputation in the young and middle-aged adult u.s. population. diabetes care. 2019;42(1):50-4. https://doi.org/10.2337/dc18-1380 21. gallagher p, o'donovan ma, doyle a, desmond d. environmental barriers, activity limitations and participation restrictions experienced by people with major limb amputation. prosthet orthot int. 2011;35(3): 278-84. doi:10.1177/0309364611407108 22. sinha r, van den heuvel wj, arokiasamy p. adjustments to amputation and an artificial limb in lower limb amputees. prosthet orthot int. 2014;38(2):115-21. doi:10.1177/0309364613489332 23. 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 24. deans sa, mcfadyen ak, rowe pj. physical activity and quality of life: a study of a lower-limb amputee population. prosthet orthot int. 2008;32(2):186-200. doi:10.1080/03093640802016514 25. granger cv. the emerging science of functional assessment: our tool for outcomes analysis. arch phys med rehabil. 1998;79(3):235-40. 26. canadapost.ca [internet]. ottawa: canada post corporation; c2019 [cited 2019 jan 29]. available from https://www.canadapost.ca 27. keith ra, granger cv, hamilton bb, sherwin fs. the functional independence measure: a new tool for rehabilitation. adv clin rehabil. 1987;1:6-18. 28. leung ec, rush pj, devlin m. predicting prosthetic rehabilitation outcome in lower limb amputee patients with the functional independence measure. arch phys med rehabil. 1996;77(6):605-8. 29. muecke l, shekar s, dwyer d, israel e, flynn jp. functional screening of lower-limb amputees: a role in predicting rehabilitation outcome? arch phys med rehabil. 1992;73(9):851-8. 30. panesar bs, morrison p, hunter j. a comparison of three measures of progress in early lower limb amputee rehabilitation. clin rehabil. 2001;15(2):157-71. doi:10.1191/026921501669259476 https://doi.org/10.33137/cpoj.v2i1.31950 https://jps.library.utoronto.ca/index.php/cpoj/index https://doi.org/10.1016/j.apmr.2014.03.010 https://doi.org/10.1016/j.dhjo.2017.03.013 https://dx.doi.org/10.1590%2f1413-78522015230200990 https://doi.org/10.1111/j.1445-2197.2006.03715.x https://doi.org/10.1177%2f153857449903300107 https://doi.org/10.1177%2f153857449903300107 https://doi.org/10.1080/03093640802492434 https://doi.org/10.3109/03093648909078214 https://doi.org/10.3109/03093648909078214 https://doi.org/%2010.1053/%20apmr.2002.34605 https://doi.org/%2010.1053/%20apmr.2002.34605 https://doi.org/10.1038/nrendo.2011.183 https://doi.org/10.1016/j.cjca.2018.03.002 https://doi.org/10.1093/ndt/gfy211 https://doi.org/10.2337/dc18-1380 https://doi.org/10.1177/0309364611407108 https://doi.org/10.1177/0309364613489332 https://doi.org/10.3109/09638288.2010.529234 https://doi.org/10.1080/03093640802016514 https://www.canadapost.ca/ https://doi.org/10.1191/026921501669259476 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 9 open access dysvascular lower extremity amputation volume 2, issue 1, article no.1, february 2019 https://jps.library.utoronto.ca/index.php/cpoj/index 31. stineman mg, shea ja, jette a, tassoni cj, ottenbacher kj, feidler r, et al. the functional independence measure: tests of scaling assumptions, structure, and reliability across 20 diverse impairment 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. 2002;83(5):613-27. https://doi.org/10.1053/apmr.2002.323 09 36. mcdonald s, sharpe l, blaszczynski a. the psychosocial impact associated with diabetes-related amputation. diabet med. 2014;31(11):1424-30. doi:10.1111/dme.12474 37. 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. 2015;96(8):1404-10. doi:10.1016/j.apmr.2015.04.001 38. fleury am, salih sa, peel nm. rehabilitation of the older vascular amputee: a review of the literature. geriatr gerontol int. 2013;13(2):264-73. doi:10.1111/ggi.12016 39. horgan o, maclachlan m. psychosocial adjustment to lower-limb amputation: a review. disabil rehabil. 2004; 26(14-15):837-50. 40. scragg p, jones a, fauvel n. psychological problems following icu treatment. anaesthesia. 2001;56(1):9-14. https://doi.org/10.1046/j.1365-2044.2001.01714.x 41. ashford r, mcgee p, kinmond k. perception of quality of life by patients 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 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 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 il u 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 il u 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 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 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 review of clinical outcomes. jbjs reviews. 2017;5(10):e10. doi:10.2106/jbjs.rvw.17.00037 2. leijendekkers ra, van hinte g, frolke jp, van de meent h, nijhuis-van der sanden mw, staal jb. comparison of bone-anchored prostheses and socket prostheses for patients with a lower extremity amputation: a systematic review. disabil rehabil. 2017 jun;39(11):1045-58. doi: 10.1080/09638288.2016.1186752 3. van eck cf, mcgough rl. clinical outcome of osseointegrated prostheses for lower extremity amputations: a systematic review of the literature. curr orthop pract. 2015;26(4):349-57. doi: 10.1097/bco.0000000000000248 4. branemark r, branemark pi, rydevik b, myers rr. osseointegration in skeletal reconstruction and rehabilitation: a review. j rehabil res dev. 2001 marapr;38(2):175-81. pubmed pmid: 11392650. epub 2001/06/08. eng. 5. kunutsor sk, gillatt d, blom aw. systematic review of the safety and efficacy of osseointegration prosthesis after limb amputation. bjs. 2018;0(0). doi: 10.1002/bjs.11005 6. atallah r, leijendekkers ra, hoogeboom tj, frolke jp. complications of bone-anchored prostheses for individuals with an extremity amputation: a systematic review. plos one. 2018;13(8):e0201821. doi:10.1371/journal.pone.0201821 7. nebergall a, bragdon c, antonellis a, karrholm j, branemark r, malchau h. stable fixation of an osseointegated implant system for above-the-knee amputees: titel rsa and radiographic evaluation of migration and bone remodeling in 55 cases. acta orthop. 2012 apr;83(2):121-8. doi: 10.3109/17453674.2012.678799 https://doi.org/10.33137/cpoj.v1i2.31326 https://doi.org/10.2106/jbjs.rvw.17.00037 https://doi.org/10.1080/09638288.2016.1186752 https://doi.org/10.1002/bjs.11005 https://doi.org/10.1371/journal.pone.0201821 https://doi.org/10.3109/17453674.2012.678799 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 9 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 8. tillander j, hagberg k, hagberg l, branemark r. osseointegrated titanium implants for limb prostheses attachments: infectious complications. clin orthop relat res. 2010 oct;468(10):2781-8. doi:10.1007/s11999-0101370-0 9. hagberg k, haggstrom e, uden m, branemark r. socket versus bone-anchored trans-femoral prostheses: hip range of motion and sitting comfort. prosthet orthot int. 2005 aug;29(2):153-63. doi:10.1080/03093640500238014 10. frossard l, stevenson n, smeathers j, lee gow d, gray s, sullivan j, et al. daily activities of a transfemoral amputee fitted with osseointegrated fixation: continuous recording of the loading for an evidence-based practice. kinesitherapie revue. 2006;6(56-57):53-62. 11. lee w, frossard l, hagberg k, haggstrom e, brånemark r. kinetics analysis of transfemoral amputees fitted with osseointegrated fixation performing common activities of daily living. clin biomech. 2007;22(6):665-73. doi:10.1016/j.clinbiomech.2007.02.005 12. frossard l, stevenson n, smeathers j, haggstrom e, hagberg k, sullivan j, et al. monitoring of the load regime applied on the osseointegrated fixation of a trans-femoral amputee: a tool for evidence-based practice. prosthet orthot int. 2008 mar;32(1):68-78. doi:10.1080/03093640701676319 13. hagberg k, branemark r, gunterberg b, rydevik b. osseointegrated trans-femoral amputation prostheses: prospective results of general and condition-specific quality of life in 18 patients at 2-year follow-up. prosthet orthot int. 2008 mar;32(1):29-41. doi:10.1080/03093640701553922 14. hagberg k, branemark r. one hundred patients treated with osseointegrated transfemoral amputation prostheses--rehabilitation perspective. j rehabil res dev. 2009;46(3):331-44. doi:10.1682/jrrd.2008.06.0080 15. haggstrom e, hagberg k, rydevik b, branemark r. vibrotactile evaluation: osseointegrated versus socketsuspended transfemoral prostheses. j rehabil res dev. 2013;50(10):1423-34. doi:10.1682/jrrd.2012.08.0135 16. van de meent h, hopman mt, frolke jp. walking ability and quality of life in subjects with transfemoral amputation: a comparison of osseointegration with socket prostheses. arch phys med rehabil. 2013 nov;94(11):2174-8. doi:10.1016/j.apmr.2013.05.020 17. hagberg k, hansson e, branemark r. outcome of percutaneous osseointegrated prostheses for patients with unilateral transfemoral amputation at two-year follow-up. arch phys med rehabil. 2014 jul 24;95(11):2120-7. doi:10.1016/j.apmr.2014.07.009 18. potter bk. from bench to bedside: a perfect fit? osseointegration can improve function for patients with amputations. clin orthop relat res. 2016 jan;474(1):357. pubmed pmid: 26497884. doi:10.1007/s11999-0154604-3 19. schalk s, jonkergouw n, van der meer f, swaan wm, aschoff h-h, van der wurff p. the evaluation of daily life activities after application of an osseointegrated prosthesis fixation in a bilateral transfemoral amputee: a case study. medicine. 2015;94(36):e1416. doi: 10.1097/md.0000000000001416 20. al muderis m, khemka a, lord s, van de meent h, fro lke j. safety of osseointegrated implants for transfemoral amputees: a two-center prospective cohort study. j bone joint surg. 2016;98(11):900-9. doi:10.2106/jbjs.15.00808 21. haket lm, frolke jp, verdonschot n, tomaszewski pk, van de meent h. periprosthetic cortical bone remodeling in patients with an osseointegrated leg prosthesis. j orthop res. 2016 jul 28. doi:10.1002/jor.23376 22. 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 23. frossard la, tranberg r, haggstrom e, pearcy m, branemark r. load on osseointegrated fixation of a transfemoral amputee during a fall: loading, descent, impact and recovery analysis. prosthet orthot int. 2010 mar;34(1):85-97. doi: 10.3109/03093640903585024 24. lee w, frossard l, hagberg k, haggstrom e, lee gow d, gray s, et al. magnitude and variability of loading on the osseointegrated implant of transfemoral amputees during walking. med eng phys. 2008 sep;30(7):825-33. doi: 10.1016/j.medengphy.2007.09.003 25. webster jb, chou t, kenly m, english m, roberts tl, bloebaum rd. perceptions and acceptance of osseointegration among individuals with lower limb amputations: a prospective survey study. j prosthet orthot. 2009;21(4):215-22. https://doi.org/10.1097/jpo.0b013e3181bfafba 26. lundberg m, hagberg k, bullington j. my prosthesis as a part of me: a qualitative analysis of living with an osseointegrated prosthetic limb. prosthet orthot int. 2011 jun;35(2):207-14. doi: 10.1177/0309364611409795 27. branemark r, berlin o, hagberg k, bergh p, gunterberg b, rydevik b. a novel osseointegrated percutaneous prosthetic system for the treatment of patients with transfemoral amputation: a prospective study of 51 patients. bone joint j. 2014 jan;96(1):10613. doi: 10.1302/0301-620x.96b1.31905 28. 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. 2018 aug https://doi.org/10.33137/cpoj.v1i2.31326 https://doi.org/10.1007/s11999-010-1370-0 https://doi.org/10.1007/s11999-010-1370-0 https://doi.org/10.1080/03093640500238014 https://doi.org/10.1016/j.clinbiomech.2007.02.005 https://doi.org/10.1080/03093640701676319 https://doi.org/10.1080/03093640701553922 https://doi.org/10.1682/jrrd.2012.08.0135 https://doi.org/10.1016/j.apmr.2013.05.020 https://doi.org/10.1016/j.apmr.2014.07.009 https://doi.org/10.1007/s11999-015-4604-3 https://doi.org/10.1007/s11999-015-4604-3 https://doi.org/10.1097/md.0000000000001416 https://doi.org/10.2106/jbjs.15.00808 https://doi.org/10.1002/jor.23376 https://doi.org/10.1097/jpo.0b013e3181ccc53d https://doi.org/10.3109/03093640903585024 https://doi.org/10.1016/j.medengphy.2007.09.003 https://doi.org/10.1177/0309364611409795 https://doi.org/10.1302/0301-620x.96b1.31905 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 10 open access assessing the provision of bone anchored limb prosthesis volume 1, issue 2, article no.4, december 2018 16:309364618791616. doi: 10.1177/0309364618791616 29. frossard l, merlo g, quincey t, burkett b, berg d. development of a procedure for the government provision of bone-anchored prosthesis using osseointegration in australia. pharmacoecon open. 2017 dec;1(4):301-14. https://doi.org/10.1007/s41669-0170032-5 30. frossard l, berg d, merlo g, quincey t, burkett b. cost comparison of socket-suspended and boneanchored transfemoral prostheses. j prosthet orthot. 2017;29(4):150-60. doi: 10.1097/jpo.0000000000000142 31. haggstrom ee, hansson e, hagberg k. comparison of prosthetic costs and service between osseointegrated and conventional suspended transfemoral prostheses. prosthet orthot int. 2013 apr;37(2):152-60. doi: 10.1177/0309364612454160 32. hansson e, hagberg k, cawson m, brodtkorb th. patients with unilateral transfemoral amputation treated with a percutaneous osseointegrated prosthesis cost effecteviness analysis. the bone & joint journal. 2018;100-b(4):527-34. doi:10.1302/0301620x.100b4.bjj-2017-0968.r1 33. frossard la, merlo g, burkett b, quincey t, berg d. cost-effectiveness of bone-anchored prostheses using osseointegrated fixation: myth or reality? prosthet orthot int. 2018 jun;42(3):318-27. doi: 10.1177/0309364617740239 34. bosmans j, geertzen j, dijkstra pu. consumer satisfaction with the services of prosthetics and orthotics facilities. prosthetics and orthotics international. 2009;33(1):69. doi: 10.1080/03093640802403803 35. geertzen jhb, gankema hgj, groothoff jw, dijkstra pu. consumer satisfaction in prosthetics and orthotics facilities. prosthetics and orthotics international. 2002;26(1):64-71. doi: 10.1080/03093640208726623 36. 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. prosthetics and orthotics international. 2003;27(3):191. doi: 10.1080/03093640308726682 37. heinemann aw, ehrlich-jones l, connelly l, semik p, fatone s. enhancing quality of prosthetic services with process and outcome information. prosthetics and orthotics international. 2016 2017/04/01;41(2):164-70. doi: 10.1177/0309364616637957 38. parasuraman a, zeithaml v, berry l. servqual: a multiple-item scale for measuring consumer perceptions of service quality. journal of retailing. 1988 //;64(1):1240. 39. peaco a, halsne e, hafner bj. assessing satisfaction with orthotic devices and services: a systematic literature review. jpo: journal of prosthetics and orthotics. 2011;23(2):95-105. doi: 10.1097/jpo.0b013e318217a0fe 40. van der linde h, hofstad cj, geertzen jhb, postema k, van limbeek j. from satisfaction to expectation: the patient's perspective in lower limb prosthetic care. disability and rehabilitation. 2007;29(13):1049-55. doi: 10.1080/09638280600948375 41. wessels rd, witte lpd. reliability and validity of the dutch version of quest 2.0 with users of various types of assistive devices. disability and rehabilitation. 2003;25(6):267-72. https://doi.org/10.1080/0963828021000031197 42. muhlbacher ac, juhnke c. patient preferences versus physicians' judgement: does it make a difference in healthcare decision making? appl health econ health policy. 2013 jun;11(3):163-80. doi: 10.1007/s40258013-0023-3 43. van voorn gak, vemer p, hamerlijnck d, ramos ic, teunissen gj, al m, et al. the missing stakeholder group: why patients should be involved in health economic modelling. applied health economics and health policy. 2016 2016//;14(2):129-33. doi: 10.1007/s40258-015-0200-7 44. schiller c, winters m, hanson hm, ashe mc. a framework for stakeholder identification in concept mapping and health research: a novel process and its application to older adult mobility and the built environment. bmc public health. 2013 may 2;13:428. https://doi.org/10.1186/1471-2458-13-428 45. reason p. the sage handbook of action research. 2008 2017/01/07. 2nd. available from: http://sk.sagepub.com/reference/the-sage-handbook-ofaction-research. 46. demers l, weiss-lambrou r, ska b. development of the quebec user evaluation of satisfaction with assistive technology (quest). assistive technology : the official journal of resna. 1996;8(1):3-13. pubmed pmid: 10159726. epub 1995/12/09. eng. 47. deutscher d, hart dl, dickstein r, horn sd, gutvirtz m. implementing an integrated electronic outcomes and electronic health record process to create a foundation for clinical practice improvement. physical therapy. 2008 feb 2008;88(2):270-85. doi: 10.2522/ptj.20060280 48. amtmann d, bamer am, kim j, bocell f, chung h, park r, et al. a comparison of computerized adaptive testing and fixed-length short forms for the prosthetic limb users survey of mobility (plus-m(tm)). prosthet orthot int. 2017 sep 1:309364617728118. doi: 10.1177/0309364617728118 49. frossard l. evaluation framework to assess benefits and harms of bone-anchored prosthesis. 6th https://doi.org/10.33137/cpoj.v1i2.31326 https://doi.org/10.1177/0309364618791616 https://doi.org/10.1097/jpo.0000000000000142 https://doi.org/10.1177/0309364612454160 https://doi.org/10.1302/0301-620x.100b4.bjj-2017-0968.r1 https://doi.org/10.1302/0301-620x.100b4.bjj-2017-0968.r1 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/ 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 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. https://doi.org/10.1080/03093640108726603 2. gholizadeh, h., e. d. lemaire, and a. eshraghi. "the evidence-base for elevated vacuum in lower limb prosthetics: literature review and professional feedback." clinical biomechanics 37 (2016): 108-116. https://doi.org/10.1016/j.clinbiomech.2016.06.005 3. samitier cb, guirao l, costea m, camós jm, pleguezuelos e. the benefits of using a vacuum-assisted socket system to improve balance and gait in elderly transtibial amputees. prosthet orthot int. 2016; 40(1):83–8. https://doi.org/10.1177/0309364614546927 4. gholizadeh h, abu osman na, eshraghi a, ali s. the effects of suction and pin/lock suspension systems on transtibial amputees’ gait performance. plos one. 2014; 9(5): e94520. https://doi.org/10.1371/journal.pone.0094520 5. czerniecki jm, gitter aj. gait analysis in the amputee: has it helped the amputee or contributed to the development of improved prosthetic components? gait posture. 1996; 4(3):258– 68. https://doi.org/10.1016/0966-6362(96)01073-9 https://doi.org/10.33137/cpoj.v2i2.32941 https://doi.org/10.1080/03093640108726603 https://doi.org/10.1016/j.clinbiomech.2016.06.005 https://doi.org/10.1177/0309364614546927 https://doi.org/10.1371/journal.pone.0094520 https://doi.org/10.1016/0966-6362(96)01073-9 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 8 cpoj gholizadeh et al. 2019 mechanical evaluation of össur unity suspension system 6. 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. https://doi.org/10.1080/17461550500069612 7. eshraghi a, abu osman na, gholizadeh h, karimi m, ali s. pistoning assessment in lower limb prosthetic sockets. prosthet orthot int. 2012; 36(1):15–24. https://doi.org/10.1177/0309364611431625 8. newton rl, morgan d, schreiber mh. radiological evaluation of prosthetic fit in below-the-knee amputees. skeletal radiol. 1988; 17(4):276–80. https://doi.org/10.1007/bf00401811 9. 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 10. caspers ca. hypobarically-controlled artificial limb for amputees. u.s. patent 5,549,709, issued august 27, 1996. 11. street g. vacuum suspension and its effects on the limb. orthopadie tech. 2006; 4:1–7. 12. rosenblatt nj, ehrhardt t, bauer a, caldwell r, fergus r. energetic cost of gait and functional mobility: a comparison of vacuum, suction, and sleeve suspensions. american academy of orthotists & prosthetists, 41st academy annual meeting & scientific symposium, 2015. 13.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. https://doi.org/10.1016/j.apmr.2011.05.019 14. balogh a. the effect of prosthesis suspension on residual limb pistoning. master thesis, retrieved from georgia institute of technology. 2008. available: http://hdl.handle.net/1853/22055 15. scott h, hughes j. investigating the use of elevated vacuum suspension on the adult pffd patient: a case study. acpoc news. 2013; 19, 7–12. 16. 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; 48(4):613–23. 17. papaioannou g, mitrogiannis c, nianios g, fiedler g. assessment of internal and external prosthesis kinematics during strenuous activities using dynamic roentgen stereophotogrammetric analysis. j prosthet orthot. 2010; 22(2):91–105. doi: 10.1097/jpo.0b013e3181cca7bb 18. convery p, murray kd. ultrasound study of the motion of the 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 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 residuum/socket interface using 3d motion capture. med eng phys. 2015;37(12):1162-1168. https://doi.org/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;49:131-139. https://doi.org/10.1016/j.medengphy.2017.08.014 4.gary sibbald r, woo ky. the biology of chronic foot ulcers in persons with diabetes. diabetes-metab res. 2008 may;24(s1):s25-30. https://doi.org/10.1002/dmrr.847 5.greenhalgh dg. wound healing and diabetes mellitus. clin plast surg 2003; 30: 37–45. doi:10.1016/s00941298(02)00066-4 6.dillingham tr, pezzin le, shore ad. reamputation, mortality, and health care costs among persons with dysvascular lower-limb amputations. arch phys med rehab. 2005 ;86(3):480-6. https://doi.org/10.1016/j.apmr.2004.06.072 7.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):186-94. doi:10.1080/03093640108726601 8.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 rehab. 2001;82(9):1286-1290. https://doi.org/10.1053/apmr.2001.25154 9.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. https://doi.org/10.1016/j.apmr.2008.07.015 10.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 11.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(3). doi:10.1682/jrrd.2009.12.0193 12.hansen c, godfrey b, wixom j, mcfadden m. incidence, severity, and impact of hyperhidrosis in people with lowerlimb amputation. j rehabil res dev. 2015;52(1). http://dx.doi.org/10.1682/jrrd.2014.04.0108 13.gonzalez eg, energy expenditure in below-knee amputees: correlation with stump length. arch phys med rehabil. 1974;55:111-9. 14.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(2):84-91. doi: 10.3109/03093649409164389 15.seymour r. prosthetics and orthotics: lower limb and spinal. philadelphia, pa, usa: lippincott williams & wilkins, 2002. 16.klute gk, rowe gi, mamishev av, ledoux wr. the thermal conductivity of prosthetic sockets and liners. https://jps.library.utoronto.ca/index.php/cpoj/index https://www.blatchford.co.uk/endolite/silcare-breathe-cushion-liner/ https://www.blatchford.co.uk/endolite/silcare-breathe-cushion-liner/ https://www.blatchford.co.uk/endolite/silcare-breathe-locking-liner/ https://www.blatchford.co.uk/endolite/silcare-breathe-locking-liner/ https://www.blatchford.co.uk/catalogue/liners/silcare-breathe-locking/ifu/938398_iss1%20-%20locking%20liner.pdf https://www.blatchford.co.uk/catalogue/liners/silcare-breathe-locking/ifu/938398_iss1%20-%20locking%20liner.pdf https://doi.org/10.1016/j.medengphy.2015.10.004 https://doi.org/10.1016/j.medengphy.2017.08.014 https://doi.org/10.1002/dmrr.847 https://doi.org/10.1016/j.apmr.2004.06.072 https://doi.org/10.1053/apmr.2001.25154 https://doi.org/10.1016/j.apmr.2008.07.015 http://dx.doi.org/10.1682/jrrd.2014.04.0108 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 7 open access perforated prosthetic liners volume 2, issue 1, article no.3, august 2019 https://jps.library.utoronto.ca/index.php/cpoj/index prosthet orthot int . 2007;31(3):292-299. https://doi.org/10.1080/03093640601042554 17.webber cm, klittich mr, dhinojwala a, davis bl. thermal conductivities of commercially available prosthetic materials. j prosthet orthot. 2014 ;26(4):212-5. doi: 10.1097/jpo.0000000000000043 18.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. https://doi.org/10.7888/juoeh.23.225 19.lake c, supan tj. the incidence of dermatological problems in the silicone suspension sleeve user. j prosthet orthot. 1997; 9: 97–106. 20.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. https://doi.org/10.1111/j.14683083.2006.01936.x 21.almassi f, emadi n, mousavi b, masumi m, souroush mr. dermatosis contributing factors in bilateral lower limb war-amputees. pak j biol sci. 2010;13(2):78-82. doi: 10.3923/pjbs.2010.78.82 22.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):134-9. doi: 10.1097/jpo.0000000000000070 23.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(3):275-279. https://doi.org/10.1177/0309364617729923 24.su pf, gard sa, lipschutz rd, kuiken ta. gait characteristics of persons with bilateral transtibial amputations. j rehabil res dev. 2007;44(4): 491–502. doi: 10.1682/jrrd.2006.10.0135 25.gailey r. review of secondary physical conditions associated with lower-limb amputation and 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 orthot int. 2008;32(1):42-49. doi: 10.1080/03093640701610615 32.charrow a, difazio m, foster l, pasquina pf, tsao jw. intradermal botulinum toxin type a injection effectively reduces residual limb hyperhidrosis in amputees: a case series. arch phys med rehabil. 2008;89(7):1407-1409. https://doi.org/10.1016/j.apmr.2007.11.054 33.han g, ceilley r. chronic wound healing: a review of current management and treatments. adv ther. 2017;34(3):599-610. doi:10.1007/s12325-017-0478-y 34.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. https://doi.org/10.1080/03093640108726603 35.goswami j, lynn r, street g, harlander m. walking in a vacuum‐assisted socket shifts the stump fluid balance. prosthet orthot int. 2003;27(2):107-13. doi: 10.1080/03093640308726666 36.gerschutz mj, denune ja, colvin jm, schober g. elevated vacuum suspension influence on lower limb amputee's residual limb volume at different 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 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 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 li m 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 lower limb amputations. clin rehabil. 1998; 12: 348– 353. https://doi.org/10.1191/026921598672393611 https://doi.org/10.33137/cpoj.v2i2.33517 https://doi.org/10.1053/apmr.2001.21962 https://doi.org/10.1191/026921598672393611 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 6 cpoj mcgrath et al. 2019 the influence of prosthetic ankles on the standing biomechanics of transtibial amputees 3.burke mj, roman v, wright v. bone and joint changes in lower limb amputees. ann. rheum. dis. 1978; 37: 252–254. http://dx.doi.org/10.1136/ard.37.3.252 4.hungerford ds, cockin j. fate of the retained lower limb joints in second world war amputees. j bone joint surg 1975; 57: 111. 5. 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 6.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: 169–172. 7.smith dg, ehde dm, legro mw, reiber ge, del aguila m, boone da. phantom limb, residual limb, and back pain after lower extremity amputations. clin. orthop. relat. res. 1999; 361: 29– 38. 8. ehde dm, czerniecki jm, smith dg, campbell km, edwards wt, jensen mp, robinson lr. chronic phantom sensations, phantom pain, residual limb pain, and other regional pain after lower limb amputation. arch phys med rehabil.2000; 81: 1039– 1044. https://doi.org/10.1053/apmr.2000.7583 9. ephraim pl, wegener st, mackenzie ej, dillingham tr, pezzin le. phantom pain, residual limb pain, and back pain in 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 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 manuscript with advice from dr henderson slater. references 1. gruber h, kovacs p, peer s, frischhut b, bodner g. sonographically guided phenol injection in painful. ajr am j roentgenol. 2004;182:952–4. doi: 10.2214/ajr.182.4.1820952 2. mathews gj, osterholm jl. painful traumatic neuromas. surg clin north am. 1972;52(5):1313–28. doi:10.1016/s00396109(16)39843-7 3. restrepo‐garces ce, marinov a, mchardy p, faclier g, avila a. pulsed radiofrequency under ultrasound guidance for persistent stump‐neuroma pain. pain pract. 2011;11(1):98-102. https://doi.org/10.1111/j.1533-2500.2010.00398.x 4. hsu e, cohen sp. postamputation pain: epidemiology, mechanisms, and treatment. j pain res. 2013;6:121. doi: 10.2147/jpr.s32299 5. ehde dm, czerniecki jm, smith dg, campbell km, edwards wt, jensen mp, et al. chronic phantom sensations, phantom pain, residual limb pain, and other regional pain after lower limb amputation. arch phys med rehabil. 2000;81(8):1039–44. https://doi.org/10.1053/apmr.2000.7583 6. montoya p, larbig w, grulke n, flor h, taub e, birbaumer n. the relationship of phantom limb pain to other phantom limb phenomena in upper extremity amputees. pain. 1997 ;72(1-2):8793. https://doi.org/10.1016/s0304-3959(97)00004-3 7. bendinger t, plunkett n. measurement in pain medicine. bja educ. 2016 sep 1;16(9):310–5. https://doiorg.proxy.bib.uottawa.ca/10.1093/bjaed/mkw014 8. perneger t v., combescure c. the distribution of p-values in medical research articles suggested selective reporting associated with statistical significance. j clin epidemiol. 2017 1;87:70–7. https://doi.org/10.1016/j.jclinepi.2017.04.003 9. kang j, yang p, zang q, he x. traumatic neuroma of the superficial peroneal nerve in a patient: a case report and review of the literature. world j surg oncol. 2016; 14(1). doi 10.1186/s12957-016-0990-6 10. restrepo-garces ce, marinov a, mchardy p, faclier g, avila a. pulsed radiofrequency under ultrasound guidance for persistent stump-neuroma pain. pain pract. 2011;11(1):98–102. https://doi.org/10.1111/j.1533-2500.2010.00398.x 11. kim yk, jung i, lee ch, kim sh, kim js, yoo and bw. pulsed radiofrequency ablation under ultrasound guidance for huge neuroma. korean j pain. 2014;27(3):290–3. http://dx.doi.org/10.3344/kjp.2014.27.3.290 12. zheng b, song l, liu h. pulsed radiofrequency of brachial plexus under ultrasound guidance for refractory stump pain: a case report. j pain res. 2017 7;10:2601–4. doi: 10.2147/jpr.s148479 13. zhang x, xu y, zhou j, pu s, lv y, chen y, et al. ultrasoundguided alcohol neurolysis and radiofrequency ablation of painful stump neuroma: effective treatments for post-amputation pain. j pain res. 2017;10:295–302. doi: 10.2147/jpr.s127157 14. jena b, paswan a, singh y, loha s, singh a, rastogi v. a comparative study of continuous versus pulsed radiofrequency discectomy for management of low backache: prospective randomized, double-blind study. anesth essays res. 2016;10(3):602. doi: 10.4103/0259-1162.186616 15. lopez wo, navarro pa, vargas md, alape e, lopez pa. pulsed radiofrequency versus continuous radiofrequency for facet joint low back pain: a systematic review. world neurosurgery. 2018. 390–6. https://doi.org/10.1016/j.wneu.2018.10.191 16.pangarkar s, miedema ml. pulsed versus conventional radio frequency ablation for lumbar facet joint dysfunction. curr phys med rehabil reports. 2014;2(1):61–5. doi 10.1007/s40141-0130040-z 17. ilfeld bm, moeller-bertram t, hanling sr, tokarz k, mariano er, loland vj, et al. treating intractable phantom limb pain with ambulatory continuous peripheral nerve blocks: a pilot study. pain med (united states). 2013;14(6):935–42. https://doiorg.proxy.bib.uottawa.ca/10.1111/pme.12080 18. gilmore c, ilfeld b, rosenow j, li s, desai m, hunter c, et al. percutaneous peripheral nerve stimulation for the treatment of chronic neuropathic postamputation pain: a multicenter, randomized, placebo-controlled trial. reg anesth pain med. 2019;44(6):637–45. http://dx.doi.org/10.1136/rapm-2018-100109 19. borghi b, d’addabbo m, borghi r. can neural blocks prevent phantom limb pain? pain manag. 201;4(4):261–6. https://doi.org/10.2217/pmt.14.17 20.chen p-j, liang h-w, chang k-v, wang t-g. ultrasoundguided injection of steroid in multiple postamputation neuromas. j clin ultrasound. 2013;41(2):122–4. https://doi.org/10.1002/jcu.21 885 21. hung yh, wu ch, özçakar l, wang tg. ultrasound-guided steroid injections for two painful neuromas in the stump of a belowelbow amputee. am j phys med rehabil. 2016;95(5):e73. doi: 10.1097/phm.0000000000000456 22. kesikburun s, yaşar e, dede i, göktepe s, tan ak. ultrasound-guided steroid injection in the treatment of stump neuroma: pilot study. j back musculoskelet rehabil. 2014;27(3):275–9. doi: 10.3233/bmr-130444 23.dumanian ga, potter bk, mioton lm, ko jh, cheesborough je, souza jm, et al. targeted muscle reinnervation treats neuroma and phantom pain in major limb amputees: a randomized clinical trial. ann 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 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 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 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/ 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-walk 1 2 167 69 85 50 trauma m left 2 c-walk 1 3 181 113 48 23 trauma m right 3 advantage dp 1 4 182 72 22 8 trauma m left 3-4 c-walk 1 5 173 76 76 59 trauma m left 3 dynamic motion 1 6 181 81 34 n.a. trauma f left 3-4 c-walk 1 7 175 92 63 44 trauma m left 3 dynamic motion 1 8 190 92 63 n.a. arterial disease m left 2-3 c-walk 1 9 185 87 62 n.a. n.a. m left 3 c-walk 1 10 182 79 41 9 trauma m left 4 triton 1 11 181 86 22 6 trauma m left 2 n.a. 12 172 87 66 2 arterial disease m left 1-2 dynamic foot 1 13 160 61 46 21 trauma f left 2 multiflex 2 14 180 85 52 29 trauma m left 4 triton 1 15 193 115 43 15 trauma m left 4 trias 1 16 175 94 62 1 arterial disease m right 3 dynamic motion 1 17 176 75 63 39 trauma m right 3 c-walk 1 18 171 69 22 3 trauma f right 3 c-walk 1 19 179 71 68 1 arterial disease m right 2 dynamic foot 1 20 179 80 47 0 trauma m left 3 c-walk 1 21 187 88 71 8 trauma m left 3 c-walk 1 22 172 60 27 3 trauma f left 2-3 c-walk 1 23 170 70 34 6 arterial disease f left 3 dynamic motion 1 24 156 63 44 1 arterial disease f right 2 sach 1 25 179 95 64 3 arterial disease m left 2-3 dynamic foot 1 26 176 67 28 3 trauma m left 3 dynamic foot 1 27 159 64 46 24 trauma f left 3 c-walk 1 28 186 79 29 29 congenital m left 4 c-walk 1 29 174 92 62 3 arterial disease m right 2 dynamic foot 1 30 173 91 59 4 arterial disease m right 1-2 greissinger plus 1 31 176 73 43 26 trauma m left 3-4 dynamic motion 1 32 175 80,5 73 54 trauma m right 3 dynamic motion 1 33 181 84 52 20 trauma f right 3 c-walk 1 34 180 92 65 4 arterial disease m left 3 c-walk 1 35 169 76,5 70 71 trauma m left 3 sach 1 36 203 144 25 8 trauma m right 2-3 ceterus 3 37 173 77 50 31 trauma m right 4 triton 1 38 176 93,5 53 1 sepsis m right 3-4 c-walk 1 39 178 117 28 1 trauma m right 3 trias 1 40 189 126 39 31 trauma m left 3 axtion 1 41 168 76 37 24 malignancy f right 3 triton 1 42 175 88 51 3 trauma m right 3 c-walk 1 43 174 75 43 n.a. n.a. f left 2 n.a. 44 176 78 44 15 trauma f left 4 triton 1 45 183 113 26 2 malignancy m right 4 triton 1 46 165 69 47 2 arterial disease f right 3 ceterus lp 3 47 172 72 41 20 trauma f left 4 c-walk 1 48 156 53 40 33 trauma f right 3 axtion 1 49 177 79 47 10 arterial disease m right 4 triton 1 50 188 109 50 8 trauma m right 3-4 n.a. 51 168 70 28 20 trauma m right 4 advantage dp 1 52 187 102 33 17 trauma m right 4 advantage dp 1 53 183 69 48 2 infection m right 3 trias 1 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 5.breakey j. gait of unilateral below-knee amputees. j prosthet orthot. 1976;1;30(3):17-24. 6.perry j, boyd la, rao ss, mulroy sj. prosthetic weight acceptance mechanics in transtibial amputees wearing the single axis, seattle lite, and flex foot. ieee trans rehabil eng.1997; 5 (4): 283–289. doi: 10.1109/86.650279 7.sanderson dj, martin pe. lower extremity kinematic and kinetic adaptations in unilateral below-knee amputees during walking. gait posture. 1997; 6: 126-36. https://doi.org/10.1016/s0966-6362(97)01112-0 8.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. https://doi.org/10.1080/03093640008726534 9.schmalz t, blumentritt s, reimers cd. selective thigh muscle atrophy in trans-tibial amputees: an ultrasonographic study. arch orthop trauma surg. 2001; 121(): 307–312. https://doi.org/10.1007/s004020000227 10. nolan l, wit a, dudziñski k, lees a, lake m, wychowañski m. adjustments in gait symmetry with walking speed in trans-femoral and trans-tibial amputees. gait posture. 2003; 17(2): 142–51. https://doi.org/10.1016/s0966-6362(02)00066-8 11. beyaert c, grumillier c, martinet n, paysant j, andré jm. compensatory mechanism involving the knee joint of the intact limb during gait in unilateral below-knee amputees. gait posture. 2008; 28 (2): 278–284. https://doi.org/10.1016/j.gaitpost.2007.12.073 12.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): 296– 300. https://doi.org/10.1016/j.gaitpost.2010.05.003 13.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; 10: 49. https://doi.org/10.1186/1743-0003-10-49 14.esposito er, wilken jm. biomechanical risk factors for knee osteoarthritis when using passive and power anklefoot 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 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 li g ib il it y 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. clin orthop relat res. 2001;383:204-7. doi:10.1097/00003086-200102000-00023 3.bradley c. importance of differentiating health status from quality of life. lancet 2001;357:7-8. doi:10.1016/s0140-6736(00)03562-5 4.the world health organization quality of life assessment (whoqol): position paper from the world health organization. soc sci med. 1995 nov; 41(10):1403-9. doi:10.1016/02779536(95)00112-k 5.world health organization. whoqol-bref: introduction, administration and generic version of the assessment. geneva, switzerland: who programme on mental health; 1996 6.hunt sm, mckenna sp, mcewen j, backett em, williams j, papp e. a quantitative approach to perceived health-status – a validationstudy. j epidemiol community health. 1980;34(4):281–6. doi:10.1136/jech.34.4.281 7.demet k, martinet n, guillemin f, paysant j, andré jm. health related quality of life and related factors in 539 persons with amputation of upper and lower limb. disabil rehabil. 2003;25:480486. doi:10.1080/0963828031000090434 8.gallagher p, maclachlan m. development and psychometric evaluation of the trinity amputation and prosthesis experience scales (tapes). rehabil psychol. 2000;45:130-154. doi:10.1037/0090-5550.45.2.130 9.legro mw, reiber gd, smith dg, delaguila 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;79:931-8. doi:10.1016/s00039993(98)900909 10.dillingham tr, pezzin le, mackenzie ej, burgess ar. use and satisfaction with prosthetic devices among persons with trauma related amputations: a long-term outcome study. am j phys med rehabil. 2001;80(8):563–71. doi:10.1097/00002060-20010800000003 11.bilodeau s, hébert r, desrosiers j. questionnaire sur la satisfaction des personnes amputées du membre inférieur face à leur prothèse: développement et validation. can j occup ther. février. 1999;66(1):23-32. doi:10.1177/000841749906600103 12.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;41:593-603. doi:10.2340/16501977-0393 https://doi.org/10.33137/cpoj.v3i1.33640 7 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 13.penn-barwell jg . outcomes in lower limb amputation following trauma: a systematic review and meta-analysis. injury. 2011;42:1474–1479. doi:10.1016/j.injury.2011.07.005 14.sinha r, van den heuvel wja (2011) a systematic literature review of quality of life in lower limb amputees, disabil rehabil, 33:11, 883-899. doi:10.3109/ 09638288.2010.514646 15.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):348353. doi:10.1191/026921598672393611 16.kulkarni j, gaine wj, buckley jg, rankine jj, adams j. chronic low back pain in traumatic lower limb amputees. clin rehabil. 2005;19(1):81. doi:10.1191/0269215505cr819oa 17.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 18.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;25:4806. doi:10.1080/0963828031000090434 19.grzebień a, chabowski m, malinowski m, uchmanowicz i, milan m, janczak d. analysis of selected factors determining quality of life in patients after lower limb amputation-a review article. polski przeglad chirurgiczny. 2017;89(2):57-61. doi:10.5604/ 01.3001.0009.8980 20.hawkins at, henry aj, cramdell dm, nguyen ll. a systematic review of functional and quality of life assessment after major lower extremity amputations. annals of vascular surgery. 2014;28(3):763780. doi:10.1016/j.avsg.2013.07.011 21.seker a, kara a, camur s, malkoc m, sonmez mm, mahirogullari m. comparison of mortality rates and functional results after transtibial and transfemoral amputations due to diabetes in elderly patients-a retrospective study. intern j surg, 2016;33:78-82. doi:10.1016/j.ijsu.2016.07.063 22.schoppen t, boonstra a, groothoff jw, de vj, göeken ln, eisma wh. physical, mental, and social predictors of functional outcome in unilateral lower-limb amputees. arch phys med rehabil 2003;84: 803-81. doi:10.1016/s0003-9993(02)04952-3 23.gauthier-gagnon c, grise mc. prosthetic profile of the amputee questionnaire: validity and reliability. 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 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 i n 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 (hs110407) by the institutional review board, northern illinois university. participants were asked to sign a consent form prior to participation in the study. references 1.ma vy, chan l, carruthers kj. incidence, prevalence, costs, and impact on disability of common conditions requiring rehabilitation in the united states: stroke, spinal cord injury, traumatic brain injury, multiple sclerosis, osteoarthritis, rheumatoid arthritis, limb loss, and back pain. arch phys med rehabil. 2014;95(5):986-995. doi: 10.1016/j.apmr.2013.10.032 2.fosse s, hartemann-heurtier a, jacqueminet s, ha van g, grimaldi a, fagot-campagna a. incidence and characteristics of lower limb amputations in people with diabetes. diabet med. 2009;26(4):391-6. doi: 10.1111/j.1464-5491.2009.02698.x 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(3):422-429. doi: 10.1016/j.apmr.2007.11.005 https://doi.org/10.33137/cpoj.v3i2.33804 8 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 4.renzi r, unwin n, jubelirer r, haag l. an international comparison of lower extremity amputation rates. ann vasc surg. 2006;20(3):346-50. doi: 10.1007/s10016-006-9044-9 5.gauthier-gagnon c, grise mc, potvin d. enabling factors related to prosthetic use by people with transtibial and transfemoral amputation. arch phys med rehabil. 1999;80(6):706-13. doi: 10.1016/s0003-9993(99)90177-6 6.felcher sm, stinner dj, krueger ca, wilken jm, gajewski da, hsu jr, et al. falls in a young active amputee population: a frequent cause of rehospitalization? mil med. 2015;180(10): 10831086. doi: 10.7205/milmed-d-14-00450 7.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):1031-1037. doi: 10.1053/apmr.2001.24295 8.wong ck, chen cc, blackwell wm, rahal rt, benoy sa. balance ability measured with the berg balance scale: a determinant of fall history in community-dwelling adults with leg amputation. j rehabil med. 2015;47(1):80-86. doi:10.2340/ 16501977-1882 9.miller wc, deathe ab, speechley m, koval j. the influence of falling, fear of falling, and balance confidence on prosthetic mobility and social activity among individuals with a lower extremity amputation. arch phys med rehabil. 2001;82(9):1238-1244. doi: 10.1053/apmr.2001.25079 10.bateni h, nuzzo n. long-term influence of ankle sprain on dynamic postural steadiness. illinois physical therapy association (ipta) meeting; 2011 september 23-24; galena, il. 11.bateni h, collins p, odeh c. comparison of the effect of cane, tripod cane tip, and quad cane on postural steadiness in healthy older adults. j prosthet orthot. 2018;30(2):84-89. doi:10.1097/ jpo.0000000000000176 12.prieto te, myklebust jb, hoffmann rg, lovett eg, myklebust bm. measures of postural steadiness: differences between healthy young and elderly adults. ieee trans biomed eng. 1996;43(9):956966. doi: 10.1109/10.532130 13.prieto te, myklebust jb, myklebust bm. characterization and modelling of postural steadiness in the elderly: a review. ieee trans rehabil eng. 1993;1:26. doi: 10.1109/86.242405 14.davids k, kingsbury d, george k, o'connell m, stock d. interacting constraints and the emergence of postural behavior in acl-deficient subjects. j mot behav. 1999;31(4):358-366. doi: 10.1080/00222899909601000 15.tjon ss, geurts ac, van't pad bosch p, laan rf, mulder t. postural control in rheumatoid arthritis patients scheduled for total knee arthroplasty. arch phys med rehabil. 2000;81(11):1489. doi: 10.1053/apmr.2000.9627 16.giacomini p, sorace f, magrini a, alessandrini m. alterations in postural control: the use of spectral analysis in stability measurement. acta otorhinolaryngol ital. 1998;18(2):83-87. 17.golomer e, dupui p, bessou p. spectral frequency analysis of dynamic balance in healthy and injured athletes. arch int physiol biochim biophys. 1994;102(3):225-229. doi:10.3109/ 13813459409007543 18.bateni h. effect of orthotic insoles on postural control. american orthotic and prosthetic association national assembly; 2011 september 19-22; las vegas, nv. 19.bateni h. changes of postural steadiness following use of prefabricated orthotic insoles. j appl biomech. 2013;29(2):174179. doi: 10.1123/jab.29.2.174 20.davis jr, campbell ad, adkin al, carpenter mg. the relationship between fear of falling and human postural control. gait posture. 2009;29(2):275-279. doi: 10.1016/j.gaitpost.2008.09.006 21.sturnieks dl, delbaere k, brodie ma, lord sr. the influence of age, anxiety and concern about falling on postural sway when standing at an elevated level. hum mov sci. 2016;49:206-215. doi: 10.1016/j.humov.2016.06.014 22.macbride a, rogers j, whylie b, freeman sj. psychosocial factors in the rehabilitation of elderly amputees. psychosomatics. 1980;21(3):258-265. doi: 10.1016/s0033-3182(80)73701-5 23.ku px, abu osman na, wan abas wa. balance control in lower extremity amputees during quiet standing: a systematic review. gait posture. 2014;39(2):672-682. doi: 10.1016/j.gaitpost. 2013.07.006 24.maurer c, peterka rj. a new interpretation of spontaneous sway measures based on a simple model of human postural control. j neurophysiol. 2005;93(1):189-200. doi: 10.1152/ jn.00221.2004. 25.duarte m, sternad d. complexity of human postural control in young and older adults during prolonged standing. exp brain res. 2008;191(3):265-276. doi: 10.1007/s00221-008-1521-7 26.forsman p, haeggstrom e, wallin a, toppila e, pyykko i. daytime changes in postural stability and repeatability of posturographic measurements. j occup environ med. 2007;49(6):591-596. doi: 10.1097/jom.0b013e3180577796 27.lafond d, corriveau h, hebert r, prince f. intrasession reliability of center of pressure measures of postural steadiness in healthy elderly people. arch phys med rehabil. 2004;85(6):896901. doi: 10.1016/j.apmr.2003.08.089 28.rocchi l, chiari l, horak fb. effects of deep brain stimulation and levodopa on postural sway in parkinson's disease. j neurol neurosurg psychiatry. 2002;73(3):267-274. doi: 10.1136/ jnnp.73.3.267 29.de haart m, geurts ac, huidekoper sc, fasotti l, van limbeek j. recovery of standing balance in postacute stroke patients: a rehabilitation cohort study. arch phys med rehabil. 2004;85(6): 886-895. doi: 10.1016/j.apmr.2003.05.012 30.hilliard mj, martinez km, janssen i, edwards b, mille ml, zhang y, et al. lateral balance factors predict future falls in community-living older adults. arch phys med rehabil. 2008;89(9): 1708-1713. doi: 10.1016/j.apmr.2008.01.023 31.winter da, prince f, frank js, powell c, zabjek kf. unified theory regarding a/p and m/l balance in quiet stance. j neurophysiol. 1996;75:2334-2343 doi: 10.1152/ jn.1996.75.6.2334 32.winter da, prince f, stergiou p, powell c. medial-lateral and anterior-posterior motor responses associated with centre of pressure changes in quiet standing. neurosci res commun 1993;12:141. 33.maki be, holliday pj, topper ak. a prospective study of postural balance and risk of falling in an ambulatory and independent elderly population. j gerontol. 1994;49(2):72-84. doi: 10.1093/geronj/49.2.m72 34.buckley jg, o'driscoll d, bennett sj. postural sway and active balance performance in highly active lower-limb amputees. am j https://doi.org/10.33137/cpoj.v3i2.33804 9 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 phys med rehabil. 2002;81(1):13-20. doi: 10.1097/00002060200201000-00004 35.patel m, fransson pa, lush d, petersen h, magnusson m, johansson r, et al. the effects of foam surface properties on standing body movement. acta otolaryngol. 2008;128(9):952-960. doi: 10.1080/00016480701827517 36.arifin n, abu osman na, ali s, gholizadeh h, abas wa. postural stability characteristics of transtibial amputees wearing different prosthetic foot types when standing on various support surfaces. sci world j. 2014. doi: 10.1155/ 2014/856279 37.arifin n, abu osman na, ali s, wan abas wa. the effects of prosthetic foot type and visual alteration on postural steadiness in below-knee amputees. biomed eng online. 2014;13(1):23. doi: 10.1186/1475-925x-13-23. 38.bateni h. changes of postural steadiness following use of prefabricated orthotic insole. j appl biomech. 2013; 29(2):174179. doi: 10.1123/jab.29.2.174 39.hlavackova p, franco c, diot b, vuillerme n. contribution of each leg to the control of unperturbed 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 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 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. 1996 oct;33(4):387– 94. 4.imam b, miller w, finlayson h, eng j, jarus t. incidence of lower limb amputation in canada. can j public heal. 2017;108(4):374–80. https://doi.org/10.17269/cjph.108.6093 5. dispelling the myths – the reality of living with amputation and prosthetic care. the war amputations of canada. 2018. 6.varma p, stineman mg, dillingham tr. epidemiology of limb loss. vol. 25, phys med rehabil clin n am. 2014. p. 1–8. https://doi.org/10.1016/j.pmr.2013.09.001 7.dobson a, el-gamil a, shimer m, davanzo je. economic value of prosthetic services among medicare beneficiaries: a claims-based retrospective cohort study. mil med. 2016;2(18):18–24. https://doi.org/10.7205/milmed-d-15-00545 8.morrison b, topping d. robotic prosthetic availability analysis. phd dissertation. worcester polytechnic institute. 2012; available from: https://digitalcommons.wpi.edu/iqp-all/776/ 9.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. https://doi.org/10.1016/s0140-6736(18)30181-8 10.canada health act [internet]. health canada; 1985 [cited 2019 dec 23]. available from: https://lawslois.justice.gc.ca/eng/acts/c-6/page-1.html 11.pharmacare prosthetic and orthotic program general statement of program policy. british columbia ministry of health services; 2009 [cited 2019 dec 23]. available from: http://docplayer.net/44652967-pharmacare-prosthetic-andorthotic-program-general-statement-of-program-policy.html 12. pharmacare prosthetic and orthotic policy manual [internet]. british columbia; pharmaceutical services division ministry of health; 2019 [cited 2019 dec 23]. available from: https://www2.gov.bc.ca/assets/gov/health/health-drugcoverage/pharmacare/prosthetics-andorthotics/po_policy_manual.pdf 13. alberta aids to daily living program manual op, orthotic and prosthetic benefits [internet]. government of alberta; 2017 [cited 2019 dec 23]. available from: https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-80452498f464c2e3/resource/1f0a6bbf-1815-4e55-8365cff783c0caf1/download/health-aadl-manual-op-orthoticsprosthetics.pdf 14.alberta aids to daily living approved product list prosthetic benefits [internet]. alberta health; 2019 [cited 2019 dec 23]. available from: https://open.alberta.ca/dataset/f3ab974d-8f09-4f45-80452498f464c2e3/resource/ac69cc5f-ed58-4a41-ae911629b080e05c/download/aadl-manual-p-products-2019-04.pdf https://doi.org/10.33137/cpoj.v2i2.33489 https://doi.org/10.1177/0309364611432794 https://doi.org/10.1007/s40141-014-0063-0 https://doi.org/10.17269/cjph.108.6093 https://doi.org/10.1016/j.pmr.2013.09.001 https://doi.org/10.7205/milmed-d-15-00545 https://digitalcommons.wpi.edu/iqp-all/776/ https://doi.org/10.1016/s0140-6736(18)30181-8 https://laws-lois.justice.gc.ca/eng/acts/c-6/page-1.html https://laws-lois.justice.gc.ca/eng/acts/c-6/page-1.html http://docplayer.net/44652967-pharmacare-prosthetic-and-orthotic-program-general-statement-of-program-policy.html http://docplayer.net/44652967-pharmacare-prosthetic-and-orthotic-program-general-statement-of-program-policy.html https://www2.gov.bc.ca/assets/gov/health/health-drug-coverage/pharmacare/prosthetics-and-orthotics/po_policy_manual.pdf https://www2.gov.bc.ca/assets/gov/health/health-drug-coverage/pharmacare/prosthetics-and-orthotics/po_policy_manual.pdf https://www2.gov.bc.ca/assets/gov/health/health-drug-coverage/pharmacare/prosthetics-and-orthotics/po_policy_manual.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/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/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. 2019;volume2, issue2, no.4. https://doi.org/10.33137/cpoj.v2i2.33489 8 cpoj howard et al. 2019 canada’s prosthetic coverage 15.saskatchewan aids to independent living program (sail) general policies [internet]. government of saskatchewan; 2018 [cited 2019 dec 23]. available from: https://pubsaskdev.blob.core.windows.net/pubsaskprod/106724/106724-sail_general_policies_jan_2018.pdf 16.the health services insurance act: prosthetic, orthotic and other medical devices insurance regulation [internet]. manitoba laws; 2015 [cited 2019 dec 23]. available from: https://web2.gov.mb.ca/laws/regs/current/_pdfregs.php?reg=53/93 17.limb prostheses (externally powered) product manual [internet]. ontario, ministry of health and long-term care; 2012 [cited 2019 dec 23]. available from: http://www.health.gov.on.ca/en/pro/programs/adp/information_te chnology/docs/limb_prostheses_externally_powered_manual.pdf 18.limb prostheses policy and administration manual [internet]. assistive devices program ministry of health & long-term care; 2016 [cited 2019 dec 23]. available from: http://www.health.gov.on.ca/en/pro/programs/adp/policies_proce dures_manuals/docs/limb_prosthesis_manual.pdf 19.tariff for devices which compensate for a motor deficiency and insured related services [internet]. régie de l’assurance maladie du québec; 2018 [cited 2019 dec 23]. available from: http://www.ramq.gouv.qc.ca/sitecollectiondocuments/tarifs appareils déficience motrice/2019/liste_appareils_def_mot_2019_01_01_en.pdf 20.medical care insurance insured services regulations [internet]. government of newfoundland and labrador;1998 [cited 2019 dec 23]. available from: https://www.health.gov.nl.ca/health/mcp/regs_1.pdf 21.medical payment schedule [internet]. government of newfoundland and labrador; 2013 [cited 2019 dec 23]. available from: https://www.health.gov.nl.ca/health/mcp/providers/full_mcp_pa yment_schedule-03_13_14.pdf 22.social development prosthetic program policy [internet]. government of new brunswick; 2016 [cited 2019 dec 23]. available from: https://www2.gnb.ca/content/dam/gnb/departments/sdds/pdf/healthservices/prosthetic.pdf 23.prosthetists guide [internet]. nova scotia wellness department of health & arm & leg prostheses program; 2018 [cited 2019 dec 23]. available from: http://msi.medavie.bluecross.ca/wpcontent/uploads/sites/3/2018/09/prosthetists-guide-september2018-combined.pdf 24.hospital and medical services insurance. department of health and social services, prince edward island; 2019 [cited 2019 dec 23]. available from: http://www.gov.pe.ca/photos/original/hss_hospital_e.pdf 25.pharmacare formulary [internet]. health pei. p.e.i.; 2019 [cited 2019 dec 23]. available from: https://www.princeedwardisland.ca/sites/default/files/publications /pei_pharmacare_formulary.pdf 26.mlinac me, feng mc. assessment of activities of daily living, self-care, and independence. arch clin neuropsychol. 2016;31(6):506–16. https://doi.org/10.1093/arclin/acw049 27.healthcare common procedure coding system. hcfa common procedure coding system. washington, d.c.: united states government printing office; 2001. 28.limb prostheses policy and administration manual [internet]. assistive devices program ministry of health and long term care; 2019 [cited 2019 dec 23]. available from: https://www.ontario.ca/page/assistive-devices-program 29.ramstrand n, brodtkorb th. considerations for developing an evidenced-based practice in orthotics and prosthetics. prosthet orthot int. 2008 mar;32(1):93–102. https://doi.org/10.1080/03093640701838190 30.highsmith jm, 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):362–277. https://doi.org/10.3109/03093646.2010.520054 31.chen c, hanson m, chaturvedi r, mattke s, hillestad r, liu hh. economic benefits of microprocessor controlled prosthetic knees: a modeling study. j neuroeng rehabil. 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 card [internet]. missassauga, the college of family physicians of canada; 2016 [cited 2019 dec 23]. available from: https://www.cfpc.ca/uploadedfiles/health_policy/_pdfs/2016re portcard.pdf 36.standards for prosthetics and orthotics, part 1: standards [internet]. world health organization; 2017 [cited 2019 dec 23]. available from: https://apps.who.int/iris/bitstream/handle/10665/259209/9789241 512480-part1-eng.pdf;jsessionid=e3ca27392240c067b7780e7 d0b6f3518?sequence=1 37.microprocessor-controlled prosthetic knees (c-leg) for patients with above knee amputations: a review of the clinical and cost-effectiveness [internet]. canadian agency for drugs and technologies in health; 2009 [cited 2019 dec 23]. available from: https://www.cadth.ca/sites/default/files/pdf/l0101_cleg_prostheses_final.pdf 38.clinical commissioning policy: microprocessor controlled prosthetic knees [internet]. england, specialised commissioning team; 2016 [cited 2019 dec 23]. available from: 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 http://www.health.gov.on.ca/en/pro/programs/adp/policies_procedures_manuals/docs/limb_prosthesis_manual.pdf http://www.health.gov.on.ca/en/pro/programs/adp/policies_procedures_manuals/docs/limb_prosthesis_manual.pdf http://www.ramq.gouv.qc.ca/sitecollectiondocuments/tarifs%20appareils%20déficience%20motrice/2019/liste_appareils_def_mot_2019_01_01_en.pdf http://www.ramq.gouv.qc.ca/sitecollectiondocuments/tarifs%20appareils%20déficience%20motrice/2019/liste_appareils_def_mot_2019_01_01_en.pdf http://www.ramq.gouv.qc.ca/sitecollectiondocuments/tarifs%20appareils%20déficience%20motrice/2019/liste_appareils_def_mot_2019_01_01_en.pdf https://www.health.gov.nl.ca/health/mcp/regs_1.pdf https://www.health.gov.nl.ca/health/mcp/providers/full_mcp_payment_schedule-03_13_14.pdf https://www.health.gov.nl.ca/health/mcp/providers/full_mcp_payment_schedule-03_13_14.pdf https://www2.gnb.ca/content/dam/gnb/departments/sd-ds/pdf/healthservices/prosthetic.pdf https://www2.gnb.ca/content/dam/gnb/departments/sd-ds/pdf/healthservices/prosthetic.pdf http://msi.medavie.bluecross.ca/wp-content/uploads/sites/3/2018/09/prosthetists-guide-september-2018-combined.pdf http://msi.medavie.bluecross.ca/wp-content/uploads/sites/3/2018/09/prosthetists-guide-september-2018-combined.pdf http://msi.medavie.bluecross.ca/wp-content/uploads/sites/3/2018/09/prosthetists-guide-september-2018-combined.pdf http://www.gov.pe.ca/photos/original/hss_hospital_e.pdf https://www.princeedwardisland.ca/sites/default/files/publications/pei_pharmacare_formulary.pdf https://www.princeedwardisland.ca/sites/default/files/publications/pei_pharmacare_formulary.pdf https://doi.org/10.1093/arclin/acw049 https://www.ontario.ca/page/assistive-devices-program https://doi.org/10.1080/03093640701838190 https://doi.org/10.3109/03093646.2010.520054 https://doi.org/10.1186/s12984-018-0405-8 https://www.rand.org/content/dam/rand/pubs/research_reports/rr2000/rr2096/rand_rr2096.pdf https://www.rand.org/content/dam/rand/pubs/research_reports/rr2000/rr2096/rand_rr2096.pdf https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/science-research/key-health-inequalities-canada-national-portrait-executive-summary/hir-full-report-eng.pdf https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/science-research/key-health-inequalities-canada-national-portrait-executive-summary/hir-full-report-eng.pdf https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/science-research/key-health-inequalities-canada-national-portrait-executive-summary/hir-full-report-eng.pdf https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/science-research/key-health-inequalities-canada-national-portrait-executive-summary/hir-full-report-eng.pdf https://www.pbo-dpb.gc.ca/web/default/files/documents/reports/2018/fsr%20sept%202018/fsr_2018_25sep2018_en_2.pdf https://www.pbo-dpb.gc.ca/web/default/files/documents/reports/2018/fsr%20sept%202018/fsr_2018_25sep2018_en_2.pdf https://www.pbo-dpb.gc.ca/web/default/files/documents/reports/2018/fsr%20sept%202018/fsr_2018_25sep2018_en_2.pdf https://www.cfpc.ca/uploadedfiles/health_policy/_pdfs/2016reportcard.pdf https://www.cfpc.ca/uploadedfiles/health_policy/_pdfs/2016reportcard.pdf https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part1-eng.pdf;jsessionid=e3ca27392240c067b7780e7%20d0b6f3518?sequence=1 https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part1-eng.pdf;jsessionid=e3ca27392240c067b7780e7%20d0b6f3518?sequence=1 https://apps.who.int/iris/bitstream/handle/10665/259209/9789241512480-part1-eng.pdf;jsessionid=e3ca27392240c067b7780e7%20d0b6f3518?sequence=1 https://www.cadth.ca/sites/default/files/pdf/l0101_c-leg_prostheses_final.pdf https://www.cadth.ca/sites/default/files/pdf/l0101_c-leg_prostheses_final.pdf 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 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 1 blatchford group, unit d antura, bond close, basingstoke, uk. 2 school 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; 2002 5.klute gk, rowe gi, mamishev av, ledoux wr. the thermal conductivity of prosthetic sockets and liners. prosthet orthot int. 2007;31:292–9. doi: 10.1080/03093640601042554 6.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;23:225–32. doi: 10.7888/ juoeh.23.225 7. 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 8. 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 9. 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;36:155–63 10.wernke mm, schroeder rm, kelley ct, denune ja, colvin jm. smart temp prosthetic liner significantly reduces residual limb temperature and perspiration. j prosthet orthot. 2015;27:134–9. doi: 10.1097/jpo.0000000000000070 11.caldwell r, fatone s. technique for perforating a prosthetic liner to expel sweat. j prosthet orthot. 2017;29:145–7. doi: 10.1097/jpo.0000000000000136 12.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. doi: 10.33137/cpoj.v2i1.32723 13.davies kc, mcgrath m, stenson a, savage z, moser d, zahedi s. using perforated liners to combat the detrimental effects of excessive sweating in lower limb prosthesis users. can prosthet orthot j. 2020;3. doi: 10.33137/cpoj.v3i2.34610 14.steer j, grudniewski p, browne m, worsley p, sobey a, dickinson a. predictive prosthetic socket design part 2: personspecific concept design using multi-objective genetic algorithms. biomech model mechanobiol. 2020;19:1347–1360. doi: 10.1007/ s10237-019-01258-7 15.hamilton m. novel approaches to evaluating and characterizing force sensor performance at body-device interfaces. [dissertation on the internet]. university of toronto; 2019 [cited 2021 march 10]. available from: http://hdl.handle.net/1807/98045 16.hamilton m, behdinan k, andrysek j. evaluating the effects of load area and sensor configuration on the performance of pressure sensors at simulated body-device interfaces. ieee sens j. 2020. doi: 10.1109/jsen.2020.2970964 17.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 [h]. 2017;231:235–42. doi: 10.1177/0954411917690764 18.gholizadeh h, lemaire ed, salekrostam r. mechanical evaluation of unity elevated vacuum suspension system. can prosthet orthot j. 2019;2. doi: 10.33137/cpoj.v2i2.32941 19.armitage le. measurement of factors affecting fit at the prosthetic socket-residual limb interface in people with transtibial amputation. [dissertation on the internet]. university of new south wales; 2020 [cited 2021 march 10]. available from: https://unsworks.unsw.edu.au/fapi/datastream/unsworks:63952/s ource02?view=true 20.wernke mm, schroeder rm, haynes ml, nolt ll, albury aw, colvin jm. progress toward optimizing prosthetic socket fit and suspension using elevated vacuum to promote residual limb health. adv wound care. 2017;6:233–9. doi: 10.1089/wound.2016.0719 21.kirtley c. clinical gait analysis: theory and practice. elsevier health sciences; 2006 22.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;91:102609. doi: 10.1016/j.jtherbio.2020.102609 https://doi.org/10.33137/cpoj.v4i1.35213 8 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 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 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 beneficiaries 17 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 italy 18 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 scoliosis 19 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 amputation 20 and edwards et al.: markov model assessing cost consequence of prosthetic rehabilitation 21 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 stroke 22 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. funding for this type of research will be critical for our outcomes and evidence to keep pace with other areas of healthcare in evolving need and value. acknowledgements none. declaration of conflicting interests the authors declare no conflict of interest. sources of support none. references 1.khan f, amatya b, hoffman k. systematic review of multidisciplinary rehabilitation in patients with multiple trauma. br j surg. 2012;99:88–96. doi: 10.1002/bjs.7776 2.meyer t, gutenbrunner c, kiekens c, skempes d, melvin jl, schedler k, et al. isprm discussion paper: proposing a conceptual description of health-related rehabilitation services. j rehabil med. 2014;46(1):1–6. doi: 10.2340/16501977-1251 https://doi.org/10.33137/cpoj.v4i2.35959 5 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 3.dusing sc, skinner ac, mayer ml. unmet need for therapy services, assistive devices, and related services: data from the national survey of children with special health care needs. ambul pediatr. 2004;4(5):448–54. doi: 10.1367/a03-202r1.1 4.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;32:231–43. doi: 10.1080/ 03093640802024955 5.roffman ce, buchanan j, allison gt. predictors of non-use of prostheses by people with lower limb amputation after discharge from rehabilitation : development and validation of clinical prediction rules. j physiother. 2014;60(4):224–31. doi: 10.1016/ j.jphys.2014.09.003 6.kayssi a, dilkas s, dance d, mestral de c, forbes t, rochenagle g. rehabilitation trends after lower extremity amputations in canada. pm&r. 2017;9(5):494–501. doi: 10.1016/j.pmrj. 2016.09.009 7.twillert s van, stuive i, geertzen jhb, postema k, lettinga at. functional performance, participation and autonomy after discharge from prosthetic rehabilitation: barriers, facilitators and outcomes. j rehabil med. 2014;46:915–23. doi: 10.2340/ 16501977-1846 8.liu h, chen c, hanson m, chaturvedi r. economic value of advanced transfemoral prosthetics. santa monica, ca: rand corporation [internet]. 2017; [cited 2021, june 26]. available from: https://www-randorg.proxy.bib.uottawa.ca/content/dam/rand/pubs/research_reports /rr2000/rr2096/rand_rr2096.pdf 9.fortington l v., rommers gm, geertzen jhb, postema k, dijkstra pu. mobility in elderly people with a lower limb amputation: a systematic review. j am med dir assoc. 2012; doi: 10.1016/j.jamda.2010.12.097 10.hutchinson af, graco m, rasekaba tm, parikh s, berlowitz dj, lim wk. relationship between health-related quality of life, comorbidities and acute health care utilisation, in adults with chronic conditions. health qual life outcomes. 2015;13(1):1–10. doi: 10.1186/s12955-015-0260-2 11.santos kp, luz sc, mochizuki l, d'orsi e. burden of disease from lower limb amputations attributable to diabetes mellitus in santa catarina state, brazil, 2008-2013. cadernos de saude publica. 2018;34:e00013116. doi: 10.1590/0102-311x00013116 12.rundell sd, goode ap, friedly jl, jarvik jg, sullivan sd, bresnahan bw. role of health services research in producing highvalue rehabilitation care. phys ther. 2015;95(12):1703–11. doi: 10.2522/ptj.20150033 13.graham je, middleton a, roberts p, mallinson t, prvu-bettger j. health services research in rehabilitation and disability the time is now. arch phys med rehabil. 2018;99:198–203. doi: 10.1016/j.apmr.2017.06.026 14.kannenberg a, seidinger s. health economics: the perspective of a prosthetic manufacturer. j prosthetics orthot. 2019;31:p49– 54. doi: 10.1097/jpo.0000000000000234 15.richmond j. economic science in lower-limb prosthetic rehabilitation: the consumer’s perspective. 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 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 interventions: proposal and validation of a new operational definition. j clin epidemiol. 2016;80:34-42. doi:10.1016/j.jclinepi.2016.08.001 8.gallagher r, donoghue j, chenoweth l, stein-parbury j. selfmanagement in older patients with chronic illness. int j nurs pract. 2008;14(5):373-82. doi:10.1111/j.1440-172x.2008.00709.x 9.lee dj. development and validation of the self-management assessment for the residuum and prosthesis (s.m.a.r.t.). (doctoral dissertation, nova southeastern university).proquest dissertations publishing. 2020;194. https://www.proquest.com/openview/941cd5a1f682214c2a95fde0 a9387540/1?pq-origsite=gscholar&cbl=18750&diss=y 10.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). doi:10.1682/jrrd.2009.04.0052 11.lee dj, veneri da, goodworth ad. self-management problemsolving tools for lower-limb prosthesis wearers: mobile app usability and acceptability study. j prosthet orthot. 2019;31(1):33-42. doi:10.1097/jpo.0000000000000216 12.knight cl. the chronic wound management decision tree: a tool for long-term care nurses. j wound ostomy continence nurs. 1996;23(2):92-9. doi:10.1016/s1071-5754(96)90068-6 13.traballesi m, delussu a, 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;48(4):613-23. https://pubmed.ncbi.nlm.nih.gov/22641248/ 14.traballesi m, porcacchia p, averna t, angioni c, lubich s, di meo f, et al. prognostic factors in prosthetic rehabilitation of bilateral dysvascular above-knee amputee: is the stump condition an influencing factor? eura medicophys. 2007;43(1):1-6. https://pubmed.ncbi.nlm.nih.gov/16955063/ 15.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 16.wegener st, mackenzie ej, ephraim p, ehde d, williams r. self-management improves outcomes in persons with limb loss. https://doi.org/10.33137/cpoj.v4i1.35098 7 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 arch phys med rehabil. 2009;90(3):373-80. doi:10.1016/ j.apmr.2008.08.222 17.waheedi m, awad a, hatoum ht, enlund h. the relationship between patients' knowledge of diabetes therapeutic goals and self-management behaviour, including adherence. int j clin pharm. 2017;39(1):45-51. doi:10.1007/s11096-016-0375-5 18.fitzgerald jt, funnell mm, anderson rm, nwankwo r, stansfield rb, piatt ga. validation of the revised brief diabetes knowledge test (dkt2). diabetes educ. 2016;42(2):178-87. doi:10.1177/0145721715624968 19.alatawi ym, kavookjian j, ekong g, alrayees mm. the association between health beliefs and medication adherence among patients with type 2 diabetes. res social adm pharm. 2016;12(6):914-25. doi:10.1016/j.sapharm.2015.11.006 20.tanenbaum ml, leventhal h, breland jy, yu j, walker ea, gonzalez js. successful self-management among non-insulintreated 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 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 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 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* 1 school of human kinetics and recreation, memorial university of newfoundland, st. john’s, newfoundland, canada. 2 department of orthotics and prosthetics, school of rehabilitation sciences, hamadan university of medical sciences, hamadan, iran. 3 janbazan medical and engineering research center (jmerc), tehran, iran. 4 faculty of medicine, memorial university of newfoundland, st. john’s, newfoundland, canada. 5 department 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 k in 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 s te ro m e d ia l z 1 p o s te ro m e d ia l z 2 p o s te ro m e d ia l z 3 p o s te ro la te ra lz 1 p o s te ro la te ra lz 2 p o s te 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 il y 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 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 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 between patients with and without diabetes. diabetes care. 2006; 29:2252-6. doi:10.2337/dc060926 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.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; 59:99-106. doi: 10.1503/cjs.013115 4.imam b, miller wc, finlayson hc, eng jj, jarus t. incidence of lower limb amputation in canada. can j public health. 2017; 108:e374-e380. doi:10.17269/cjph.108.6093 5.kayssi a, de mestral c, forbes tl, roche-nagle g. predictors of hospital readmissions after lower extremity amputations in canada. j vasc surg. 2016; 63:688-95. doi:10.1016/j.jvs.2015.09.017. 6.hussain ma, al-omran m, salata k, sivaswamy a, forbes tl, sattar n, et al. population-based secular trends in lower-extremity amputation for diabtes and peripheral vascular disease. cmaj. 2019; 191:e955-61. doi:10.1503/cmaj.190134 7.franz d, zheng y, leeper nj, chandra v, montez-rath m, chang ti. trends in rates of lower extremity amputation among patients with end-stage renal disease who receive dialysis. jama intern med. 2018; 178(8):1025-1032. doi:10.1001/ jamainternmed.2018.2436. 8.hickson lj, rule ad, thorsteinsdottir b, shields rc, porter ie, fleming md, et al. predictors of early mortality and readmissions among dialysis patients undergoing lower extremity amputation. j vasc surg. 2018; 68(5):1505‐1516. doi:10.1016/j.jvs.2018.03.408 9.harding jl, pavkov me, gregg ew, burrows nr. trends of nontraumatic lower-extremity amputation in end-stage renal disease and diabetes: united states, 2000-2015. diabetes care 2019; 42(8):1430-1435. doi:10.2337/dc19-0296 10.dossa cd, shepard ad, amos am, kupin wl, reddy dj, elliott jp et al. results of lower extremity amputations in patients with end-stage renal disease. j vasc surg. 1994; 20:14-19. doi: 10.1016/0741-5214(94)90170-8 11.arneja as, 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 12.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. 13.wukich dk, ahn j, raspovic km, gottschalk fa, la fontaine j, lavery la. comparison of transtibial amputations in diabetic patients with and without end-stage renal disease. foot & ankle int. 2017; 38(4): 388-396. doi:10.1177/1071100716688073 14.chopra a, azarbal af, jung e, abraham cz, liem tk, landry gj, et al. ambulation and functional outcome after major lower extremity amputation. j vasc surg. 2018; 67:1521-1529. doi: 10.1016/j.jvs.2017.10.051 15.marquez mg, kowgier m, journeay ws. comorbidity and nonprosthetic inpatient rehabilitation outcomes after dysvascular lower extremity amputation. can prosth orthot j. 2020; 3(1). doi: 10.33137/cpoj.v3i1.33916 16.cheng r, smith sr, kalpakjian cz. comorbidity has no impact on unplanned discharge or functional gains in persons with dysvascular amputation. j rehabil med. 2019; 51(5):369-375. doi: 10.2340/16501977-2554. https://doi.org/10.33137/cpoj.v3i2.34471 7 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 17.lucke c, beindorff n, roy t, hoy l, lucke c. rehabilitation of lower extremity amputation due to peripheral arterial occlusive disease in patients with end-stage renal failure. vasc surg. 1999; 33(1): 33–40. doi:10.1177/153857449903300107 18.jassal sv, karaboyas a, comment la, bieber ba, morgenstern h, sen a, et al. functional dependence and mortality in the international dialysis outcomes and practice patterns study (dopps). am j kidney dis. 2016; 67(2):283‐292. doi: 10.1053/j.ajkd.2015.09.024 19.fleury am, salih sa, peel nm. rehabilitation of the older vascular amputee: a review of the literature. geriatr gerontol int. 2013; 13(2):264-273. doi:10.1111/ggi.12016 20.goldberg jb, goodney pp, cronenwett jl, baker f. the effect of risk and race on lower extremity amputations among medicare diabetic patients. j vasc surg 2012; 56(6):1663-1668. doi: 10.1016/j.jvs.2012.05.100 21.fard b, geertzen jhb, dijkstra pu. return home after dysvascular major amputation of the lower limb: a multicentre observational study in the netherlands. j rehabil med. 2020; 52(1):jrm00008. doi:10.2340/16501977-2631 22.stineman mg, kwong pl, kurichi je, prvu-bettger ja, vogel wb, maislin g, et al. the effectiveness of inpatient rehabilitation in the acute postoperative phase of care after transtibial or transfemoral amputation: study of an integrated health care delivery system. arch phys med rehabil. 2008; 89:1863-72. doi: 10.1016/j.apmr.2008.03.013 23.czerniecki jm, turner ap, williams rm, hakimi kn, norvell dc. the effect of rehabilitation in a comprehensive inpatient rehabilitation unit on mobility outcome after dysvascular lower extremity amputation. arch phys med rehabil. 2012; 93(8):1384‐ 1391. doi:10.1016/j.apmr.2012.03.019 24.dillingham tr, pezzin le. rehabilitation setting and associated mortality and medical stability among persons with amputations. arch phys med rehabil. 2008; 89:1038-1045. doi:10.1016/ j.apmr.2007.11.034 25.hamilton bb, laughlin ja, fiedler rc, granger cv. interrater reliability of the 7-level functional independence measure (fim). scand j rehabil med. 1994; 26:115-119. doi:10.2340/ 165019771994263115119 26.keith ra, granger cv, hamilton bb, sherwin fa. the functional independence measure: a new tool for rehabilitation. adv clin rehabil. 1987; 1:6-18. pmid: 3503663 27.czyrny jj, merill a. rehabilitation of amputees with end-stage renal disease. am j phys med rehabil. 1994; 72:353-357. doi: 10.1097/00002060-199409000-00009 28.charlson me, pompei p, ales kl, mackenzie cr. a new method of classifying prognostic comorbidity in longitudinal studies: development and validation. j chronic dis. 1987; 40:373-383. doi: 10.1016/0021-9681(87)90171-8 29.charlson me, charlson re, briggs w, hollenberg j. can disease management target patients most likely to generate high costs? the impact of comorbidity. j gen intern med. 2007; 22(4):464-469. doi: 10.1007/s11606-007-0130-7 30.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 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 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 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: 10.3109/03093646. 2010.520054 4.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):84-93. doi: 10.1186/s12984-018-0405-8 5.hirsch ja, leslie-mazwi tm, nicola gn, barr rm, bello ja, donovan wd, et al. current procedural terminology; a primer. j neurointerv surg. 2015;7(4):309-312. doi: 10.1136/neurintsurg2014-011156 6.goldman ah, kates s. pay-for-performance in orthopedics: how we got here and where we are going. curr rev musculoskelet med. 2017;10(2):212-217. doi: 10.1007/s12178-017-9404-9 7.strazzabosco m, allen ji, teisberg eo. value-based care in hepatology. hepatology. 2017; 65(5):1749-1755. doi: 10.1002/ hep.29042 8.patel k, presser e, george m, mcclellan m. shifting away from fee-for-service: alternative approaches to payment in gastroenterology. clin gastroenterol hepatol. 2016; 14(4):497-506. doi: 10.1016/j.cgh.2015.06.025 9.kaye dr, miller dc, ellimoottil c. alternative payment models and urology. curr opin urol. 2017; 27(4):360-365. doi: 10.1097/mou.0000000000000403 10.hirsch ja, rosenkrantz ab, ansari sa, manchikanti l, nicola gn. macra 2.0: are you ready for mips? j neurointerv surg. 2017; 9(7):714-716. doi: 10.1136/neurintsurg-2016-012845 11.lichtenstein rl. the united states' health care system: problems and solutions. surv ophthalmol. 1993; 38(3):310-316; discussion 316-317. doi: 10.1016/0039-6257(93)90080-q 12.stevens pm, highsmith mj, sutton bs. measuring value in the provision of lower-limb prostheses. j prosthet orthot. 2019; 31(1s):23-31. doi: 10.1097/jpo.0000000000000232 13.fairley m. l-codes: are they meeting the needs of o&p? [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 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 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 il u 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, morris ad, leese gp. mortality and hospitalization in patients after amputation: a comparison between patients with and without diabetes. diabetes care. 2006; 29:2252-6. doi:10.2337/dc060926 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.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; 59:99-106. doi: 10.1503/cjs.013115 4.imam b, miller wc, finlayson hc, eng jj, jarus t. incidence of lower limb amputation in canada. can j public health. 2017; 108:e374-e380. doi: 10.17269/cjph.108.6093 5.kayssi a, de mestral c, forbes tl, roche-nagle g. predictors of hospital readmissions after lower extremity amputations in canada. j vasc surg. 2016; 63:688-95. doi:10.1016/j.jvs. 2015.09.017 6.hussain ma, al-omran m, salata k, sivaswamy a, forbes tl, sattar n, et al. population-based secular trends in lower-extremity amputation for diabtes and peripheral vascular disease. cmaj. 2019; 191:e955-61. doi: 10.1503/cmaj.190134 7.vogel tr, petroski gf, kruse rl. impact of amputation level and comorbidities on functional status of nursing home residents after lower extremity amputation. j vasc surg. 2014; 59:1323-1330. doi: 10.1016/j.jvs.2013.11.076 8.melchiorre pj, findley t, boda w. functional outcome and comorbidity indexes in the rehabilitation of the traumatic versus the vascular unilateral lower limb amputee. am j phys med rehabil. 1996; 75:9-14. 9.lavery la, van houtum wh, armstrong dg. institutionalization following diabetes-related lower extremity amputation. am j med. 1997; 103:383-388. doi:10.1016/s0002-9343(97)00163-0 10.dillingham tr, pezzin le. rehabilitation setting and associated mortality and medical stability among persons with amputations. arch phys med rehabil. 2008; 89:1038-1045. doi:10.1016/ j.apmr.2007.11.034 11.dillingham tr, yacub jn, pezzin le. determinants of postacute care discharge destination after dysvascular lower limb amputation. pm r. 2011; 3:336-344. doi:10.1016/j.pmrj. 2010.12.019 12.kayssi a, dilkas s, dance dl, de mestral c, forbes tl, rochenagle g. rehabilitation trends after lower extremity amputations in canada. pm r. 2016; 9:494-501. doi: 10.1016/j.pmrj.2016.09.009 13.stineman mg, kwong pl, kurichi je, prvu-bettger ja, vogel wb, maislin g, et al. the effectiveness of inpatient rehabilitation in the acute postoperative phase of care after transtibial or transfemoral amputation: study of an integrated health care delivery system. arch phys med rehabil. 2008; 89:1863-72. doi: 10.1016/j.apmr.2008.03.013 14.charlson me, pompei p, ales kl, mackenzie cr. a new method of classifying prognostic comorbidity in longitudinal studies: development and validation. j chronic dis. 1987; 40:373-383. doi:10.1016/0021-9681(87)90171-8 15.charlson me, charlson re, briggs w, hollenberg j. can disease management target patients most likely to generate high costs? the impact of comorbidity. j gen intern med. 2007; 22(4):464-469. doi:10.1007/s11606-007-0130-7 16.hamilton bb, laughlin ja, fiedler rc, granger cv. interrater reliability of the 7-level functional independence measure (fim). scand j rehabil med. 1994; 26:115-119. 17.keith ra, granger cv, hamilton bb, sherwin fa. the functional independence measure: a new tool for rehabilitation. adv clin rehabil. 1987; 1:6-18. pmid: 3503663 18.chopra a, azarbal af, jung e, abraham cz, liem tk, landry gj, et al. ambulation and functional outcome after major lower extremity amputation. j vasc surg. 2018; 67:1521-1529. doi: 10.1016/j.jvs.2017.10.051 19.cheng r, smith sr, kalpakjian cz. comorbidity has no impact on unplanned discharge or functional gains in persons with dysvascular amputation. j rehabil med. 2019; 51(5):369-375. doi: 10.2340/16501977-2554. 20.mayo al, cimino sr, hitzig sl. a depiction of rehabilitation patients 65 years and younger with dysvascular lower extremity amputation. can prosthet orthot j. 2019; 2(1):1 doi: 10.33137/cpoj.v2i1.31950 21. 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 22.batten h, kuys s, mcphail s, varghese p, mandrusiak a. are people with lower limb amputation changing? a seven-year analysis of patient characteristics at admission to inpatient rehabilitation and at discharge. disabil rehabil. 2019; 41(26):32033209. doi:10.1080/09638288.2018.1492033 23.taylor sm, kalbaugh ca, blackhurst dw, hamontree se, cull dl, messich hs, et al. preoperative clinical factors predict postoperative functional outcomes after major lower limb amputation: an analysis of 553 consecutive patients. j vasc surg. 2005; 42: 227-235. doi: 10.1016/j.jvs.2005.04.015 24.arneja as, 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 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 perspiration discomfort inside prostheses: literature review. 2014. doi:10.1682/jrrd.2013.06.0133. 5.hansen c, godfrey b, wixom j, mcfadden m. incidence, severity, and impact of hyperhidrosis in people with lowerlimb amputation. j rehabil res dev. 2015; 52. doi:10.1682/jrrd.2014.04.0108. 6.strutton dr, kowalski jw, glaser da, stang pe. us prevalence of hyperhidrosis and impact on individuals with axillary hyperhidrosis: results from a national survey. j am acad dermatol. 2004; 51: 241–248. doi:10.1016/j.jaad.2003.12.040. 7.shibasaki m, kondo n, crandall cg. non-thermoregulatory modulation of sweating in humans. exerc sport sci rev. 2003; 31: 34–39. doi:10.1097/00003677-200301000-00007. 8.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. 9.gonzalez eg. energy expenditure in below-knee amputees: correlation with stump length. arch phys med rehabil. 1974; 55: 111–119. doi:10005281082. 10.seymour r. prosthetics and orthotics: lower limb and spinal. lippincott williams & wilkins; 2002. 11.klute gk, rowe gi, mamishev av, ledoux wr. the thermal conductivity of prosthetic sockets and liners. prosthet orthot int. 2007; 31: 292–299. doi:10.1080/03093640601042554. 12.warner rr, stone kj, boissy yl. hydration disrupts human stratum corneum ultrastructure. j invest dermatol. 2003; 120: 275–84. doi:10.1046/j.1523-1747.2003.12046.x. 13.ham r, cotton lt. limb amputation: from aetiology to rehabilitation. springer; 2013. 14.greenhalgh dg. wound healing and diabetes mellitus. clin plast surg. 2003; 30: 37–45. doi:10.1016/s0094-1298(02)000664. 15.caputo gm, cavanagh pr, ulbrecht js, gibbons gw, karchmer aw. assessment and management of foot disease in patients with diabetes. n engl j med. 1994; 331: 854–860. doi:10.1056/nejm199409293311307. 16.renshaw b. observations on the role of water in the susceptibility of human skin to injury by vesicant vapors. j invest dermatol. 1947; 9: 75–85. doi:10.1038/jid.1947.71. 17.hurkmans jfgm, boddé he, driel lmjv, doorne hv, junginger he. skin irritation caused by transdermal drug delivery systems during long-term (5 days) application. br j dermatol. 1985; 112: 461–7. doi:10.1111/j.1365-2133.1985.tb02321.x. 18.de macedo gmc, nunes s, barreto t. skin disorders in diabetes mellitus: an epidemiology and physiopathology review. diabetol metab syndr. 2016; 8: 63. doi:10.1186/s13098-0160176-y. 19.ashraff s, siddiqui ma, santos d, carline t. complications of stump healing among diabetic population. turk j endocrinol metab. 2018; 22: 91–7. doi:10.25179/tjem.2018-59880. 20.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: 275–280. doi:10.2337/dc08-1639. 21.izumi y, satterfield k, lee s, harkless lb. risk of reamputation in diabetic patients stratified by limb and level of amputation: a 10year observation. diabetes care. 2006; 29: 566–570. doi:10.2337/diacare.29.03.06.dc05-1992. https://doi.org/10.33137/cpoj.v3i2.34610 10 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 22.dillingham tr, pezzin le, shore ad. reamputation, mortality, and health care costs among persons with dysvascular lower-limb amputations. arch phys med rehabil. 2005; 86: 480–486. doi:10.1016/j.apmr.2004.06.072. 23.susak z, minkov r, isakov e. the use of methenamine as an antiperspirant for amputees. prosthet orthot int. 1996; 20: 172–5. doi:10.3109/03093649609164439. 24.charrow a, difazio m, foster l, pasquina pf, tsao jw. intradermal botulinum toxin type a injection effectively reduces residual limb hyperhidrosis in amputees: a case series. arch phys med rehabil. 2008; 89: 1407–9. doi:10.1016/j.apmr.2007.11.054. 25.kern u, kohl m, seifert u, schlereth t. botulinum toxin type b in the treatment of residual limb hyperhidrosis for lower limb amputees: a pilot study. am j phys med rehabil. 2011; 90: 321– 329. doi:10.1097/phm.0b013e31820636fd. 26.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. 27.wernke mm, schroeder rm, kelley ct, denune ja, colvin jm. smarttemp prosthetic liner significantly reduces residual limb temperature and perspiration. jpo j prosthet orthot. 2015; 27: 134–139. 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/ 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]. [cited 2021 jan 4]. available from: https://www.ohchr.org/en/hrbodies/tbpetitions/pages/hrtbpeti tions.aspx 8.world health organization [internet]. germany european region [internet]. 2017; [cited 2021 march 12]. available from: https://www.who.int/health-laws/countries/deu-en.pdf?ua=1 9.ndis. disability-related health supports operational guideline [internet]. 2019; [cited 2021 march 16]. available from: https://www.ndis.gov.au/about-us/operational-guidelines/disabilityrelated-health-supports-operational-guideline 10.nhs england. clinical commissioning policy: multi-grip upper limb prosthetics [internet]. 2015; [cited 2021 march 17]. available from: https://www.england.nhs.uk/commissioning/wpcontent/uploads/sites/12/2015/10/d01pc-mlti-grip-uppr-limboct15.pdf 11.nhs england. rehabilitation and disability [internet]. [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 https://www.newswire.ca/news-releases/canada-accedes-to-the-optional-protocol-to-the-united-nations-convention-on-the-rights-of-persons-with-disabilities-701804101.html#:~:text=accession%20to%20the%20optional%20protocol,the%20convention%20have%20been%20violated https://www.newswire.ca/news-releases/canada-accedes-to-the-optional-protocol-to-the-united-nations-convention-on-the-rights-of-persons-with-disabilities-701804101.html#:~:text=accession%20to%20the%20optional%20protocol,the%20convention%20have%20been%20violated https://www.newswire.ca/news-releases/canada-accedes-to-the-optional-protocol-to-the-united-nations-convention-on-the-rights-of-persons-with-disabilities-701804101.html#:~:text=accession%20to%20the%20optional%20protocol,the%20convention%20have%20been%20violated https://www.newswire.ca/news-releases/canada-accedes-to-the-optional-protocol-to-the-united-nations-convention-on-the-rights-of-persons-with-disabilities-701804101.html#:~:text=accession%20to%20the%20optional%20protocol,the%20convention%20have%20been%20violated https://www.newswire.ca/news-releases/canada-accedes-to-the-optional-protocol-to-the-united-nations-convention-on-the-rights-of-persons-with-disabilities-701804101.html#:~:text=accession%20to%20the%20optional%20protocol,the%20convention%20have%20been%20violated https://www.ohchr.org/en/hrbodies/tbpetitions/pages/hrtbpetitions.aspx https://www.ohchr.org/en/hrbodies/tbpetitions/pages/hrtbpetitions.aspx https://www.who.int/health-laws/countries/deu-en.pdf?ua=1 https://www.ndis.gov.au/about-us/operational-guidelines/disability-related-health-supports-operational-guideline https://www.ndis.gov.au/about-us/operational-guidelines/disability-related-health-supports-operational-guideline https://www.england.nhs.uk/commissioning/wp-content/uploads/sites/12/2015/10/d01pc-mlti-grip-uppr-limb-oct15.pdf https://www.england.nhs.uk/commissioning/wp-content/uploads/sites/12/2015/10/d01pc-mlti-grip-uppr-limb-oct15.pdf https://www.england.nhs.uk/commissioning/wp-content/uploads/sites/12/2015/10/d01pc-mlti-grip-uppr-limb-oct15.pdf https://www.england.nhs.uk/commissioning/spec-services/npc-crg/group-d/d01/ https://www.england.nhs.uk/commissioning/spec-services/npc-crg/group-d/d01/ 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 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 critical leg ischemia. a population-based longitudinal outcome study of 321 patients. acta orthop scand. 1996;67(5):459–465. doi: 10.3109/17453679608996668 2.miller t, rajib p, forthofer m, wurdeman s. impact of time to receipt of prosthesis on total healthcare costs 12 months postamputation. am j phys med rehabil. 2020;99(11):1026-1031. doi: 10.1097/phm.0000000000001473 3.spoorendonk ja, krol m, alleman c. the burden of amputation in patients with peripheral arterial disease (pad) in the netherlands. j cardiovasc surg (torino). 2019; 61(4):435-444 doi: 10.23736/s0021-9509.19.10936-6 4.fortington l v, rommers gm, geertzen jhb, postema k, dijkstra pu. mobility in elderly people with a lower limb amputation: a systematic review. j am med dir assoc. 2012;13(4):319–325. doi: 10.1016/j.jamda.2010.12.097 5.hagberg k, brånemark r, hägg o. questionnaire for persons with a transfemoral amputation (q-tfa): initial validity and reliability of a new outcome measure. j rehabil res dev. 2004;41(5):695–705. 6.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 7.fajardo-martos i, roda o, zambudio-periago r, buenocavanillas a, hita-contreras f, sánchez-montesinos i. predicting successful prosthetic rehabilitation in major lower-limb amputation patients: a 15-year retrospective cohort study. brazilian j phys ther. 2018;22(3):205–214. doi:10.1016/j.bjpt.2017.08.002 8.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 9.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 10.meulenbelt hej, geertzen jhb, jonkman mf, dijkstra pu. skin problems of the stump in lower limb amputees: 1. a clinical study. acta derm venereol. 2011;91(2):173–177. doi: 10.2340/ 00015555-1040 11.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):1996–2010. doi: 10.1109/tbme.2017.2775100 12.muller md. atlas of amputations and limb deficiencies: surgical, prosthetic, and rehabilitation principles. 4th ed. krajbich ji, pinzur ms, potter b, stevens pm, editors. american academy of orthopaedic surgeons; 2016. chapter 43. 13.johannesson a, larsson gu, ramstrand n, lauge-pedersen h, wagner p, atroshi i. outcomes of a standardized surgical and rehabilitation program in transtibial amputation for peripheral vascular disease: a prospective cohort study. am j phys med rehabil. 2010;89(4):293–303. doi: 10.1097/phm.0b013e3181cf1 bee 14.fletcher dd, andrews kl, hallett jw, butters ma, rowland cm, jacobsen sj. trends in rehabilitation after amputation for geriatric patients with vascular disease: implications for future health resource allocation. arch phys med rehabil. 2002;83(10):1389–93. doi: 10.1053/apmr.2002.34605 https://doi.org/10.33137/cpoj.v3i2.34672 12 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 15.kamrad i, söderberg b, örneholm h, hagberg k. swedeampthe swedish amputation and prosthetics registry: 8-year data on 5762 patients with lower limb amputation show sex differences in amputation level and in patient-reported outcome. acta orthop. 2020;22:1-7. doi:10.1080/17453674.2020.1756101 16.davie-smith f, hebenton j, scott 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 404 not found 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 ti fi c a ti o n s c re e n in g in c lu 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, 2014 26 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., 2010 24 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., 2008 20 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., 1999 21 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., 2011 25 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., 2017 18 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., 2009 19 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., 2019 27 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., 2005 22 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., 2007 23 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., 2014 28 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 med. 2009;360(23):2390–2393. doi: 10.1056/nejmp0900963 4.inouye sk, studenski s, tinetti me, kuchel ga. geriatric syndromes: clinical, research, and policy implications of a core geriatric concept. j am geriatr soc. 2007;55(5):780-791. doi: 10.1111/j.1532-5415.2007.01156.x 5.soriano ta, decherrie lv, thomas dc. falls in the communitydwelling older adult: a review for primary-care providers. clin interv aging. 2007;2(4):545-553. doi: 10.2147/cia.s1080 6.ambrose af, paul g, hausdorff jm. risk factors for falls among older adults: a review of the literature. maturitas. 2013;75(1):51-61. doi: 10.1016/j.maturitas.2013.02.009 7.eibling d. balance disorders in older adults. clin geriatr med. 2018;34(2):175-181. doi: 10.1016/j.cger.2018.01.002 8.mulasso a, roppolo m, gobbens rj, rabaglietti e. mobility, balance and frailty in community‐dwelling older adults: what is the best 1‐year predictor of falls? geriatr gerontol int. 2016;17(10):1463-1469. doi: 10.1111/ggi.12893 9.perry sd. evaluation of age-related plantar-surface insensitivity and onset age of advanced insensitivity in older adults using https://doi.org/10.33137/cpoj.v4i1.35132 9 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 vibratory and touch sensation tests. neurosci lett. 2006;392(12):62-67. doi: 10.1016/j.neulet.2005.08.060 10.moreland jd, richardson ja, goldsmith ch, clase cm. muscle weakness and falls in older adults: a systematic review and metaanalysis. j am geriatr soc. 2004;52(7):1121-1129. doi: 10.1111/j.1532-5415.2004.52310.x 11.vieira er, berean c, paches d, costa l, décombasdeschamps n, caveny p, et al. risks and suggestions to prevent falls in geriatric rehabilitation: a participatory approach. bmj qual saf. 2011;20(5):440-448. doi: 10.1136/bmjqs.2010.042382 12.waterval nfj, nollet f, harlaar j, brehm m. precision orthotics: optimising ankle foot orthoses to improve gait in patients with neuromuscular diseases; protocol of the proof-afo study, a prospective intervention study. bmj open. 2017;7(2):1-9. doi: 10.1136/bmjopen-2016-013342 13.ramstand n, ramstrand s. aaop state-of-the-science evidence report: the effect of ankle-foot orthoses on balance – a systematic review. j prosthet orthot. 2010;22(10):4-23. doi: 10.1097/jpo.0b013e3181f379b7 14.international society for prosthetics and orthotics. prosthetic and orthotic services; [internet]. [cited 2020 february 20]; available from: https://www.ispoint.org/page/poservices 15.arksey h, o’malley l. scoping studies: toward a methodological framework. int j soc res methodol. 2005;8(1):19-32. doi: 10.1080/1364557032000119616 16.casp uk. casp quantitative studies checklist [internet]. oxford: casp uk; 2018 [cited 2020 march 2]. available from: https://casp-uk.net/wp-content/uploads/2018/03/caspqualitative-checklist-2018_fillable_form.pdf 17.mcmaster university. qualitative studies critical review form (version 2.0); [internet]. 2007 [cited 2020 march 2]. available from: https://healthsci.mcmaster.ca/docs/librariesprovider130/defaultdocument-library/critical-review-form-qualitative-studies-version-21.pdf?sfvrsn=6723c450_2 18.nikamp cdm, buurke jh, van der palen j, hermens hj, rietman js. six-month effects of early or delayed provision of an ankle-foot orthosis in patients with sub(acute) stroke: a randomized controlled trial. clin rehabil. 2017;31(12):1616–1624. doi: 10.1177/0269215517709052 19.simons cdm, van asseldonk ehf, van der kooij h, geurts ach, buurke jh. ankle-foot orthoses in stroke: effects on functional balance, weight-bearing asymmetry and the contribution of each lower limb to balance control. clin biomech. 2009;24(9):769-775. doi: 10.1016/j.clinbiomech.2009.07.006 20.chen ck, hong w, chu n, lau y, lew h, tang s. effects of an anterior ankle-foot orthosis on postural stability in stroke patients with hemiplegia. am j phys med rehabil. 2008;87(10):815-820. doi: 10.1097/phm.0b013e31817c150e 21.chen cl, yeung k, wang c, chu h, yeh c. anterior ankle-foot orthosis effects on postural stability in hemiplegic patients. arch phys med rehabil. 1999;80(12):1587-1592. doi: 10.1016/s00039993(99)90335-0 22.wang r, yen l, lee c, lin p, wang m, yang y. effects of an ankle-foot orthosis on balance performance in patients with hemiparesis of different durations. clin rehabil. 2005;19(1):37-44. doi: 10.1i91/0269215505cr797oa 23.wang r, lin p, lee c, yang y. gait and balance performance improvements attributable to ankle-foot orthosis in subjects with hemiparesis. am j phys med rehabil. 2007;86(7):556-562. doi: 10.1097/phm.0b013e31806dd0d 24.cakar e, durmus o, tekin l, dincer u, kiralp mz. the anklefoot orthosis improves balance and reduces fall risk of chronic spastic hemiparetic patients. eur j phys rehabil med. 2010;46(3):363-368. 25.doğan a, mengüllüoğlu m, özgirgin n. evaluation of the effect of ankle-foot orthosis use on balance and mobility in hemiparetic stroke patients. disabil rehabil. 2011;33(15-16):1433-1439. doi: 10.3109/09638288.2010.533243 26.bigelow k, jackson k. immediate influence of carbon composite ankle-foot orthoses on balance and gait in individuals with peripheral neuropathy: a pilot study. j prosthet orthot. 2014;26(4):220-227. doi: 10.1097/jpo.0000000000000040 27.wang c, goel r, rahemi h, zhang q, lepow b, najafi b. effectiveness of daily use of bilateral custom-made ankle-foot orthoses on balance, fear of falling, and physical activity in older adults: a randomized controlled trial. gerontology. 2019;65:299307. doi: 10.1159/000494114 28.yalla sv, crews rt, fleischer ae, grewal g, ortiz j, najafi b. an immediate effect of custom-made ankle foot orthoses on postural stability in older adults. clin biomech. 2014;29(10):10811088. doi: 10.1016/j.clinbiomech.2014.10.007 29.aveyard h. doing a literature review in health and social care: a practical guide. 3rd ed. new york: mcgraw-hill ryerson; 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., 2019 27 high high moderate moderate 3 chen et al., 2008 20 high high moderate moderate 3 bigelow & jackson, 2014 26 moderate high low high 3 wang et al., 2005 22 moderate high moderate moderate 2 wang, et al., 2007 23 moderate moderate low moderate 2 simons et al., 2009 19 moderate low low moderate 2 yalla et al., 2014 28 low moderate low moderate 2 nikamp et al., 2017 18 moderate high moderate low 2 doğan et al., 2011 25 low moderate low moderate 1 cakar et al., 2010 24 low moderate low moderate 1 chen et al., 1999 21 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, 2014 26 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., 2010 24 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., 1999 21 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., 2008 20 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., 2011 25 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., 2017 18 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., 2009 19 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., 2019 27 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., 2005 22 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., 2007 23 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., 2014 28 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 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 interpreted data, contributed to the drafting of the manuscript and read and approved the final manuscript. sources of support this work was supported by the emhseed program from the university of toronto. ethical approval ethical approval was not needed for this study. references 1.blumentritt s. a new biomechanical method for determination of static prosthetic alignment. prosthet. orthot. int. 1997;21:107–13. doi:10.3109/03093649709164538. 2.jones me, steel jr, bashford gm, davidson ir. static versus dynamic prosthetic weight bearing in elderly trans-tibial amputees. prosthet. orthot. int. 1997;21:100–6. doi:10.3109/ 03093649709164537. 3.dumbleton t, buis awp, mcfadyen a, mchugh bf, mckay g, murray kd, et al. dynamic interface pressure distributions of two transtibial prosthetic socket concepts. j rehabil res dev. 2009;46:405–16. doi:10.1682/jrrd.2008.01.0015. 4.rajtukova v, hudak r, zivcak j, halfarova p, kudrikova r. pressure distribution in transtibial prostheses socket and the stump interface. procedia eng. 2014;96:374–81. doi:10.1016/ j.proeng.2014.12.106. 5.al-fakih ea, abu osman na, mahmad adikan fr. techniques for interface stress measurements within prosthetic sockets of transtibial amputees: a review of the past 50 years of research. sensors. 2016;16. doi:10.3390/s16071119. 6.parmar s, khodasevych i, troynikov o. evaluation of flexible force sensors for pressure monitoring in treatment of chronic venous disorders. sensors. 2017;17:1923. doi:10.3390/ s17081923. 7.khodasevych i, parmar s, troynikov o. flexible sensors for pressure therapy: effect of substrate curvature and stiffness on sensor performance. sensors. 2017;17:2399. doi:10.3390/ s17102399. 8.parmar s, khodasevych i, troynikov o. evaluation of flexible force sensors for pressure monitoring in treatment of chronic venous disorders. sensors. 2017;17:1923. doi:10.3390/ s17081923. 9.likitlersuang j, leineweber mj, andrysek j. evaluating and improving the performance of thin film force sensors within body and device interfaces. med eng phys. 2017;48:206–11. doi:10.1016/j.medengphy.2017.06.017. 10.khodasevych i, parmar s, troynikov o. flexible sensors for pressure therapy: effect of substrate curvature and stiffness on sensor performance. sensors. 2017;17:2399. doi:10.3390/ s17102399. 11.ren l, jones rk, howard d. predictive modelling of human walking over a complete gait cycle. j. biomech. 2007;40: 1567–74. doi:10.1016/j.jbiomech.2006.07.017. 12.sensitronics llc. fsr 101 force sensing resistor theory and applications. 2017. [cited 2021 may 16]. available from: https://sensitronics.com/pdf/sensitronics_fsr_101.pdf 13.tekscan. flexiforce® sensors users manual. 2010. [cited 2021 may 16]. available from: https://www.tekscan.com/sites/default/files/flexiforce%20sensors %20revl.pdf 14.interlink electronics. fsr integration guide and evaluation parts catalog. vol. 1.0,. 2007. [cited 2021 may 16]. available from: https://www.interlinkelectronics.com/request-integrationguides 15.hamilton m, behdinan k, andrysek j. evaluating the effects of load area and sensor configuration on the performance of pressure sensors at simulated body-device interfaces. ieee sens. j. 2020;20:5187–94. doi:10.1109/jsen.2020.2970964. 16.dabling jg, filatov a, wheeler jw. static and cyclic performance evaluation of sensors for human interface pressure measurement. conf proc ieee eng med biol soc. 2012:162–5. doi:10.1109/embc.2012.6345896. 17.al-fakih ea, abu osman na, mahmad adikan fr. techniques for interface stress measurements within prosthetic sockets of transtibial amputees: a review of the past 50 years of research. sensors. 2016;16. doi:10.3390/s16071119. 18.polliack aa, sieh rc, craig dd, landsberger s, mcneil dr, ayyappa e. scientific validation of two commercial pressure sensor https://doi.org/10.33137/cpoj.v4i1.36059 https://sensitronics.com/pdf/sensitronics_fsr_101.pdf https://www.tekscan.com/sites/default/files/flexiforce%20sensors%20revl.pdf https://www.tekscan.com/sites/default/files/flexiforce%20sensors%20revl.pdf https://www.interlinkelectronics.com/request-integration-guides https://www.interlinkelectronics.com/request-integration-guides 10 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 systems for prosthetic socket fit. prosthet. orthot. int. 2000;24:63– 73. doi:10.1080/03093640008726523. 19.castellini p, montanini r, revel gm. development of a film sensor for static and dynamic force measurement. rev. sci. instrum. 2002;73:3378. doi:10.1063/1.1499211. 20.troynikov o, ashayeri e. 3d body scanning method for closefitting garments in sport and medical applications. ergonomics australia hfesa 2011 conference edition, 2011, p. 11–6. doi:10.15221/11.239. 21.derler s, spierings ab, schmitt ku. anatomical hip model for the mechanical testing of hip protectors. med eng phys. 2005;27:475–85. doi:10.1016/j.medengphy.2005.02.001. 22.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. p i mech eng h. 2017;231:235–42. doi: 10.1177/0954411917690764. 23.schofield js, evans kr, hebert js, marasco pd, carey jp. the effect of biomechanical variables on force sensitive resistor error: implications for calibration and improved accuracy. j. biomech. 2016;49:786–92. doi:10.1016/j.jbiomech.2016.01.022. 24.hollinger a, wanderley mm. evaluation of commerical forcesensing resistors. international conference on new interfaces for musical expression, paris, france: 2006, p. 4–8. 25.schofield js, evans kr, hebert js, marasco pd, carey jp. the effect of biomechanical variables on force sensitive resistor error: implications for calibration and improved accuracy. j. biomech. 2016;49:786–92. doi:10.1016/j.jbiomech.2016.01.022. 26.ferguson-pell m, hagisawa s, bain d. evaluation of a sensor for low interface pressure applications. med eng phys. 2015;22:657–63. doi:10.1016/s1350-4533(00)00080-1. 27.ren l, jones rk, howard d. predictive modelling of human walking over a complete gait cycle. j. biomech. 2007;40:1567–74. doi:10.1016/j.jbiomech.2006.07.017. 28.ferguson-pell m. design criteria for the measurement of pressure at body/support interface. p i mech eng h. 1980;9:209– 14. doi:10.1243/emed_jour_1980_009_052_02. 29.qtc single-point sensors. peratech holdco limited 2017. [cited 2021 may 19]. available from: https://www.peratech.com/assets/uploads/datasheets/peratechqtc-datasheet-sp200-series-nov15.pdf 30.castellini p, montanini r, revel gm. development of a film sensor for static and dynamic force measurement. rev. sci. instrum. 2002;73:3378. doi:10.1063/1.1499211. 31.díaz s, stephenson jb, labrador ma. use of wearable sensor technology in gait, balance, and range of motion analysis. appl. sci. 2020;10. doi:10.3390/app10010234. 32.muro-de-la-herran a, garcía-zapirain b, méndez-zorrilla a. gait analysis methods: an overview of wearable and nonwearable systems, highlighting clinical applications. sensors. 2014;14:3362–94. doi:10.3390/s140203362. https://doi.org/10.33137/cpoj.v4i1.36059 https://www.peratech.com/assets/uploads/datasheets/peratech-qtc-datasheet-sp200-series-nov15.pdf https://www.peratech.com/assets/uploads/datasheets/peratech-qtc-datasheet-sp200-series-nov15.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 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 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. 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 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 p 6 canada c-leg p 7 usa mp lower limb prostheses p 5 usa mpk a, h 10 usa genium r 73 germany c-leg h, m 40 france c-leg p has 74 france kenevo p has 75 france rheo p has 81 france plié p has 77 italy c-leg r, m 78 italy mpk r, m 79 uk mpk p 60 uk orthoses neurologic knee instability p 8 sweden kenevo h, m, r 49 sweden osteointegration r 80 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 savings 83 country’s per-capita gross domestic product (gdp) 84 icer accepted for payment as reference us dialysis usd 50,000 85 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. linking the regulatory and reimbursement process. health econ. 2017;26(s1):13–29. doi:10.1002/hec.3479 2.drummond m, griffin a, tarricone r. economic evaluation for devices and drugs – same or different? values health. 2009; 12(4):402–406. doi:10.1111/j.1524-4733.2008.00476_1.x 3.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 4.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): 12291242. doi:10.1682/jrrd.2014.01.0031 5.microprocessor-controlled lower limb prostheses, health technology assessment [internet]. washington state health care authority, usa, 2011, [cited 2020 oct 28]. available from: www.hca.wa.gov/assets/program/mc_lower_prosthetic_final_repo rt%5b1%5d.pdf 6. update otto bock c-leg® and more: a review of microprocessor controlled prosthetic knees [internet]. worksafe bc, vancouver, 2009, [cited 2020 oct 28]. available from: www.worksafebc.com/resources/health-careproviders/guides/otto-bock-c-leg-first-update?lang=en 7.ho c,fitzsimmons h. microprocessor-controlled prosthetic knees (c-leg) for patients with above-knee amputations: a review of the clinical and cost-effectiveness [internet]. canadian agency for drugs and technologies in health (cadth). ottawa, canada, 2009, [cited 2020 oct 28]. available from: www.cadth.ca/media/pdf/l0101_c-leg_prostheses_final.pdf 8.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 9.fatoye c, betts a, odeyemi a, fatoye f, odeyemi i. educating public health about disability and giving people with disability the same opportunity as people without disability: descriptive analysis. value health.2019;22(2):s310.doi:10.1016/j.jval.2019.04.1505 10.chen c, hanson m, chaturvedi r, mattke s, hillestad r, liu hh. economic benefits of microprocessor controlled prosthetic knees: a modeling study. j neuroeng rehabil. 2018;15:62. doi:10.1186/ s12984-018-0405-8 11.medicare budget fy 2018 [internet]. u.s. department of health and human services (hhs). washington, dc, usa, [cited 2020 oct 28]. available from: www.hhs.gov/about/budget/fy2018/budget-inbrief/cms/medicare/index.html 12.medicare referring provider dmepos utilization fy 2018 [internet]. centers for medicare and medicaid services (cms). baltimore, md, usa, 2019. [cited 2020 oct 28]. available from: www.cms.gov/research-statistics-data-and-systems/statisticstrends-and-reports/medicare-provider-charge-data/dme2018 13.hartman m, martin ab, benson j, catlin a, national health expenditure accounts team. national health care spending in 2018: growth driven by accelerations in medicare and private insurance spending. health aff (millwood). 2020;39(1):8-17. doi:10.1377/ hlthaff.2019.01451 14.national health expenditure data [internet]. centers for medicare & medicaid services. baltimore, md, usa, 2020, [cited 2020 oct 28]. available from: https://www.cms.gov/researchstatistics-data-and-systems/statistics-trends-andreports/nationalhealthexpenddata 15.berchick, edward r, jessica c. barnett, rachel d. upton. health insurance coverage in the united states: 2018, current population reports [internet]. u.s. department of commerce, 2019, [cited 2020 oct 28]. available from: www.census.gov/content/dam/census/library/publications/2019/d emo/p60-267.pdf 16.social protection: total public and primary private health insurance [internet]. oecd.stat, organisation for economic cooperation and development, france, 2016. [cited 2020 oct 28]. available from: https://stats.oecd.org/index.aspx?queryid=30137# 17.organisation for economic cooperation and development [internet]. health at a glance 2013: oecd indicators. [cited 2020 oct 28]. available from: http://www.oecd.org/els/healthsystems/health-at-a-glance-2013.pdf 18.davis k, schoen c, stremikis k. mirror, mirror on the wall: how the performance of the us health care system compares internationally: 2010 update [internet]. the commonwealth fund. [cited 2020 oct 28]. available from: http://www.commonwealthfund.org/publications/fundreports/2010/jun/mirror-mirror-update.aspx. 19.guidelines for regulatory impact analysis [internet]. u.s. department of health and human services (hhs). office of the assistant secretary for planning and evaluation. washington, d.c., usa, 2016, [cited 2020 oct 28]. available from: https://aspe.hhs.gov/system/files/pdf/242926/hhs_riaguidance. pdf 20.baicker k, chandra a. do we spend too much on health care? n eng j med. 2020;383(7):605-608. doi:10.1056/nejmp2006099. 21.medicare program integrity manual. chapter 13: local coverage determinations [internet]. centers for medicare and medicaid (cms). baltimore, md, usa, 2019, [cited 2020 oct 28]. available from: www.cms.gov/regulations-andguidance/guidance/manuals/downloads/pim83c13.pdf 22.patient protection and affordable care act [internet]. 111th u.s. congress. public law 111-148. washington, d.c., 2010, [cited 2020 oct 28]. available from: https://www.govinfo.gov/content/pkg/plaw111publ148/pdf/plaw-111publ148.pdf 23.evidence and perspectives on funding healthcare in canada [internet]. the university of british columbia. centre for health services and policy research. [cited 2020 oct 28]. available from: https://healthcarefunding.ca/key-issues/current-funding/ 24.canada´s health care system [internet]. government of canada. [cited 2020 oct 28]. available from: www.canada.ca/en/healthcanada/services/canada-health-care-system.html 25.canada health act [internet]. health canada, 1985, [cited 2020 oct 28]. available from: https://laws-lois.justice.gc.ca/eng/acts/c6/page-1.html https://doi.org/10.33137/cpoj.v4i2.35298 http://www.hca.wa.gov/assets/program/mc_lower_prosthetic_final_report%5b1%5d.pdf http://www.hca.wa.gov/assets/program/mc_lower_prosthetic_final_report%5b1%5d.pdf http://www.worksafebc.com/resources/health-care-providers/guides/otto-bock-c-leg-first-update?lang=en http://www.worksafebc.com/resources/health-care-providers/guides/otto-bock-c-leg-first-update?lang=en http://www.cadth.ca/media/pdf/l0101_c-leg_prostheses_final.pdf http://www.hhs.gov/about/budget/fy2018/budget-in-brief/cms/medicare/index.html http://www.hhs.gov/about/budget/fy2018/budget-in-brief/cms/medicare/index.html http://www.cms.gov/research-statistics-data-and-systems/statistics-trends-and-reports/medicare-provider-charge-data/dme2018 http://www.cms.gov/research-statistics-data-and-systems/statistics-trends-and-reports/medicare-provider-charge-data/dme2018 https://www.cms.gov/research-statistics-data-and-systems/statistics-trends-and-reports/nationalhealthexpenddata https://www.cms.gov/research-statistics-data-and-systems/statistics-trends-and-reports/nationalhealthexpenddata https://www.cms.gov/research-statistics-data-and-systems/statistics-trends-and-reports/nationalhealthexpenddata http://www.census.gov/content/dam/census/library/publications/2019/demo/p60-267.pdf http://www.census.gov/content/dam/census/library/publications/2019/demo/p60-267.pdf https://stats.oecd.org/index.aspx?queryid=30137 http://www.oecd.org/els/health-systems/health-at-a-glance-2013.pdf http://www.oecd.org/els/health-systems/health-at-a-glance-2013.pdf http://www.commonwealthfund.org/publications/fund-reports/2010/jun/mirror-mirror-update.aspx http://www.commonwealthfund.org/publications/fund-reports/2010/jun/mirror-mirror-update.aspx https://aspe.hhs.gov/system/files/pdf/242926/hhs_riaguidance.pdf https://aspe.hhs.gov/system/files/pdf/242926/hhs_riaguidance.pdf http://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/pim83c13.pdf http://www.cms.gov/regulations-and-guidance/guidance/manuals/downloads/pim83c13.pdf https://www.govinfo.gov/content/pkg/plaw-111publ148/pdf/plaw-111publ148.pdf https://www.govinfo.gov/content/pkg/plaw-111publ148/pdf/plaw-111publ148.pdf https://healthcarefunding.ca/key-issues/current-funding/ http://www.canada.ca/en/health-canada/services/canada-health-care-system.html http://www.canada.ca/en/health-canada/services/canada-health-care-system.html https://laws-lois.justice.gc.ca/eng/acts/c-6/page-1.html https://laws-lois.justice.gc.ca/eng/acts/c-6/page-1.html 11 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 26.anis ah, guh d, wang x. a dog's breakfast: prescription drug coverage varies widely across canada. medical care. 2001;39(4):315-26. doi: 10.1097/00005650-200104000-00003 27.jaswal a. valuing health in canada [internet]. canada 2020, canada, 2013, [cited 2020 oct 28]. available from: http://canada2020.ca/wp-content/uploads/2013/06/canada-2020analytical-commentary-no-3-valuing-health-in-canadafinal.pdf 28.howard cw, saraswat dk, mcleod g, yeung a, jeong d, lam j. canada’s prosthetic coverage: a review of provincial prosthetic policy. can prosthet orthot j. 2019;2(2):no.4. doi: 10.33137/cpoj. v2i2.33489 29.ochalek j, lomas j, claxton k. assessing health opportunity costs for the canadian health care systems [internet]. analysis for the patented medicine prices review board. university of york, uk, 2018, [cited 2020 oct 28]. available from: http://www.pmprbcepmb.gc.ca/cmfiles/consultations/new_guidelines/canada_rep ort_2018-03-14_final.pdf 30.creating, facilitating and promoting sustainable health technology assessment (hta) cooperation in europe [internet]. european network for health technology assessment eunethta, [cited 2020 oct 28]. available from: https://eunethta.eu/ 31.european medical device regulation overview [internet]. european commission. [cited 2020 oct 28]. available from: https://ec.europa.eu/health/md_sector/overview_en 32.health expenditure [internet]. federal statistical office. [cited 2020 oct 28]. available from: https://www.destatis.de/de/themen/gesellschaftumwelt/gesundheit/gesundheitsausgaben/_inhalt.html 33.the german health care system [internet]. the federal ministry of health, 2020, [cited 2021 july 20]. available from: https://www.bundesgesundheitsministerium.de/fileadmin/dateien/ 5_publikationen/gesundheit/broschueren/200629_bmg_das_de utsche_gesundheitssystem_en.pdf 34.sozialgesetzbuch-rehabilitation und teilhabe von menschen mit behinderung [social code (sgb ix) book nine: rehabilitation and participation of persons with disabilities] [internet]. 2021, [cited 18 aug 2021]. available from: https://www.arbeitsagentur.de/datei/dok_ba015587.pdf 35.sozialgesetzbuch (sgb v) fünftes buch gesetzliche krankenversicherung [social code (sgb v) book five: statutory health insurance, section 27 sgb v medical treatment [internet]. 2021, [cited 18 aug 2021]. available from: https://www.sozialgesetzbuch-sgb.de/sgbv/27.html 36.sozialgesetzbuch (sgb) fünftes buch (v)– gesetzliche krankenversicherung –(sgb v) [social code (sgb) book five (v): statutory health insurance (sgb v)] [internet]. 2021, [cited 18 aug 2021]. available from: https://www.arbeitsagentur.de/datei/dok_ba015585.pdf 37.deutschland bundesgericht [jurisprudence germany federal social court] [internet]. 2004, [cited 2020 oct 28]. available from: https://dejure.org/dienste/vernetzung/rechtsprechung?gericht=bs g&datum=16.09.2004&aktenzeichen=b%203%20kr%2020/04% 20r 38.verfahrensordnung zur weiterentwicklung des hilfsmittelverzeichnisses [rules of procedure for keeping the list of medical aids up-to-date] [internet]. gkv-spitzenverband. [cited 2020 oct 28]. available from: http://gkvspitzenverband.de/krankenversicherung/hilfsmittel/hilfsmittelverzei chnis/verfahrensordnung/himi_vo.jsp 39.allgemeine methoden [internet]. german institute for quality and efficiency in health care (iqwig). [cited 2020 oct 28]. available from: www.iqwig.de/de/methoden/methodenpapier.3020.html 40.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 health econ. 2020;21(3):437-49. doi:10.1007/s10198-01901138-y 41.haute autorité de santé [internet]. ministry of health france. [cited 2020 oct 28]. available from: http://www.has-sante.fr 42.commission nationale d’évaluation des dispositifs médicaux et des technologies de santé, [national commission for the evaluation of medical devices and health technologies] [internet]. cnedimts haute autorité de santé. [cited 2020 oct 28]. available from: https://www.has-sante.fr/jcms/c_419486/qu-est-ce-que-lacredimts 43.formal description of process for controlled introduction of medial aids in skåne region [internet]. [cited 2020 oct 28]. available from:https://vardgivare.skane.se/siteassets/1.vardriktlinjer/hjalpmedel/anvisningar/rutiner/ordnat-inforande-avnya-hjalpmedel/ordnat-inforande-av-nya-hjalpmedel.pdf 44.health technology assessment – hta [internet].stockholm hta process. [cited 2021 july 20]. available from: https://vardgivarguiden.se/utveckling/vardutveckling/hta/ 45.hälsooch sjukvårdsstyrelsen [the national board of health and medical services] [internet]. västra götaland region. [cited 2021 july 20]. available from: https://www.vgregion.se/politik/politisk-organisation/namnder-ochstyrelser-for-halso--och-sjukvard/halso--och-sjukvardsstyrelsen/ 46.assessment of methods in health care and social services [internet]. swedish agency for health technology assessment and assessment of social services (sbu). [cited 2020 oct 28]. available from: http://www.sbu.se/contentassets/76adf07e270c48efaf67e3b560b7 c59c/eng_metodboken.pdf 47.swedeamp – amputationsoch protesregister för nedre extremiteten [swedish amputations and prosthesis registry for lower limb amputations] [internet]. [cited 2021 july 20]. available from: https://swedeamp.com 48.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 patient-reported outcome, acta orthopaedica, 2020 (91):4, 464-470. doi:10.1080/ 17453674. 2020.1756101 49.kuhlmann a., hagberg k, kamrad i, ramstrand n, seidinger s, berg h. a microprocessor-controlled prosthetic knee compared to non-microprocessor-controlled knees in individuals aged over 65 in sweden: a cost-effectiveness and budget-impact analysis. presented as poster at the virtual ispor europe 16 – 19 nov 2020. doi: 10.1016/j.jval.2020.08.1036 50.kozierkiewicz a, trąbka w, romaszewski a, gajda k, gilewski d. definition of the “health benefit basket” in poland. eur j health econom. 2005;1;6(1):58-65. doi: 10.1007/s10198-005-0320-3 https://doi.org/10.33137/cpoj.v4i2.35298 http://canada2020.ca/wp-content/uploads/2013/06/canada-2020-analytical-commentary-no-3-valuing-health-in-canada-final.pdf http://canada2020.ca/wp-content/uploads/2013/06/canada-2020-analytical-commentary-no-3-valuing-health-in-canada-final.pdf http://canada2020.ca/wp-content/uploads/2013/06/canada-2020-analytical-commentary-no-3-valuing-health-in-canada-final.pdf http://www.pmprb-cepmb.gc.ca/cmfiles/consultations/new_guidelines/canada_report_2018-03-14_final.pdf http://www.pmprb-cepmb.gc.ca/cmfiles/consultations/new_guidelines/canada_report_2018-03-14_final.pdf http://www.pmprb-cepmb.gc.ca/cmfiles/consultations/new_guidelines/canada_report_2018-03-14_final.pdf https://eunethta.eu/ https://ec.europa.eu/health/md_sector/overview_en https://www.destatis.de/de/themen/gesellschaft-umwelt/gesundheit/gesundheitsausgaben/_inhalt.html https://www.destatis.de/de/themen/gesellschaft-umwelt/gesundheit/gesundheitsausgaben/_inhalt.html https://www.bundesgesundheitsministerium.de/fileadmin/dateien/5_publikationen/gesundheit/broschueren/200629_bmg_das_deutsche_gesundheitssystem_en.pdf.%20assessed%2011.11.2020 https://www.bundesgesundheitsministerium.de/fileadmin/dateien/5_publikationen/gesundheit/broschueren/200629_bmg_das_deutsche_gesundheitssystem_en.pdf.%20assessed%2011.11.2020 https://www.bundesgesundheitsministerium.de/fileadmin/dateien/5_publikationen/gesundheit/broschueren/200629_bmg_das_deutsche_gesundheitssystem_en.pdf.%20assessed%2011.11.2020 https://www.arbeitsagentur.de/datei/dok_ba015587.pdf https://www.sozialgesetzbuch-sgb.de/sgbv/27.html https://www.arbeitsagentur.de/datei/dok_ba015585.pdf https://dejure.org/dienste/vernetzung/rechtsprechung?gericht=bsg&datum=16.09.2004&aktenzeichen=b%203%20kr%2020/04%20r https://dejure.org/dienste/vernetzung/rechtsprechung?gericht=bsg&datum=16.09.2004&aktenzeichen=b%203%20kr%2020/04%20r https://dejure.org/dienste/vernetzung/rechtsprechung?gericht=bsg&datum=16.09.2004&aktenzeichen=b%203%20kr%2020/04%20r http://gkv-spitzenverband.de/krankenversicherung/hilfsmittel/hilfsmittelverzeichnis/verfahrensordnung/himi_vo.jsp http://gkv-spitzenverband.de/krankenversicherung/hilfsmittel/hilfsmittelverzeichnis/verfahrensordnung/himi_vo.jsp http://gkv-spitzenverband.de/krankenversicherung/hilfsmittel/hilfsmittelverzeichnis/verfahrensordnung/himi_vo.jsp http://www.iqwig.de/de/methoden/methodenpapier.3020.html http://www.has-sante.fr/ https://www.has-sante.fr/jcms/c_419486/qu-est-ce-que-la-credimts https://www.has-sante.fr/jcms/c_419486/qu-est-ce-que-la-credimts https://vardgivare.skane.se/siteassets/1.-vardriktlinjer/hjalpmedel/anvisningar/rutiner/ordnat-inforande-av-nya-hjalpmedel/ordnat-inforande-av-nya-hjalpmedel.pdf https://vardgivare.skane.se/siteassets/1.-vardriktlinjer/hjalpmedel/anvisningar/rutiner/ordnat-inforande-av-nya-hjalpmedel/ordnat-inforande-av-nya-hjalpmedel.pdf https://vardgivare.skane.se/siteassets/1.-vardriktlinjer/hjalpmedel/anvisningar/rutiner/ordnat-inforande-av-nya-hjalpmedel/ordnat-inforande-av-nya-hjalpmedel.pdf https://vardgivarguiden.se/utveckling/vardutveckling/hta/ https://www.vgregion.se/politik/politisk-organisation/namnder-och-styrelser-for-halso--och-sjukvard/halso--och-sjukvardsstyrelsen/ https://www.vgregion.se/politik/politisk-organisation/namnder-och-styrelser-for-halso--och-sjukvard/halso--och-sjukvardsstyrelsen/ http://www.sbu.se/contentassets/76adf07e270c48efaf67e3b560b7c59c/eng_metodboken.pdf http://www.sbu.se/contentassets/76adf07e270c48efaf67e3b560b7c59c/eng_metodboken.pdf https://swedeamp.com/ 12 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 51.kawalec p, sagan a, stawowczyk e, kowalska-bobko i, mokrzycka a. implementation of the 2011 reimbursement act in poland: desired and undesired effects of the changes in reimbursement policy. health policy. 2016;1;120(4):356-61. doi: 10.1016/j.healthpol.2016.02.010 52.kawalec p, sagan a, stawowczyk e, kowalska-bobko i, mokrzycka a. implementation of the 2011 reimbursement act in poland: desired and undesired effects of the changes in reimbursement policy. health policy. 2016;120(4):356-61. doi:10.1016/j.healthpol.2016.02.010 53.agencja oceny technologii medycznych i taryfikacji [agency for health technology assessment and tariff system]. [cited 2021 july 20]. available from: http://www.aotmit.gov.pl 54.list of countries by gdp (nominal) [internet]. wikipedia. [cited 17 aug 2021]. available from: https://en.wikipedia.org/wiki/list_of_countries_by_gdp_(nominal) 55.national institute for health and care excellence (nice) “nice technology appraisal guidance” [internet]. [cited 17 aug 2021]. available from: https://www.nice.org.uk/about/what-we-do/ourprogrammes/nice-guidance/nice-technology-appraisal-guidance. 56.kelly j and wilson l. what is the clinical and cost effectiveness of microprocessor-controlled artificial knees compared with nonmicroprocessor-controlled alternatives? [internet]. glasgow: healthcare improvement scotland. 2012; [cited 17 aug 2021]. available from: https://www.crd.york.ac.uk/crdweb/printpdf.php?accessionnu mber=32013000467&copyright=health+technology+assessment +%28hta%29+database%3cbr+%2f%3ecopyright+%26copy% 3b+2014+nhs+quality+improvement+scotland+%28nhs+qis% 29%3cbr+%2f%3e&accessionnumber=32013000467&copyright =health+technology+assessment+%28hta%29+database%3cb r+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improv ement+scotland+%28nhs+qis%29%3cbr+%2f%3e 57.delivering authoritative, evidence-informed guidance on health technologies in wales [internet]. health technology wales. [cited 17 aug 2021]. available from: https://www.healthtechnology.wales/about/our-appraisal-process 58.the global guide to market access -northern ireland’s payer stakeholders [internet]. global healthpr. [cited 17 aug 2021]. available from: https://www.globalhealthpr.com/serivices/northernireland/ 59.mccabe c, claxton k, culyer aj. the nice cost-effectiveness threshold: what it is and what that means. pharmacoeconomics, 2008;26(9):733-44. doi:10.2165/00019053-200826090-00004 60.clinical commissioning policy: microprocessor controlled prosthetic knees [internet]. national health service england. [cited 17 aug 2021]. available from: https://www.england.nhs.uk/wpcontent/uploads/2016/12/clin-comm-pol-16061p.pdf 61.liu g, wu eq, ahn j, kamae i, xie j, yang h. the development of health technology assessment in asia: current status and future trends. value health reg issues. 2020;21:39-44. doi: 10.1016 /j.vhri.2019.08.472 62.kamae i, thwaites r, hamada a, fernandez jl. health technology assessment in japan: a work in progress. j med econ. 2020;23(4):317-22. doi: 10.1080/13696998.2020.1716775 63.sakamoto h, rahman m, nomura s, okamoto e, koike s, yasunaga h, et al. japan: health system review. health syst transit. 2018;8(1):23–187 64.health at a glance 2017: oecd indicators “how does japan compare?” [internet]. oecd, 2017, [cited 17 aug 2021]. available from: https://www.oecd.org/japan/health-at-a-glance-2017-keyfindings-japan-in-english.pdf 65.ogura h, komoto s, shiroiwa t and fukuda t. “exploring the application of cost-effectiveness evaluation in the japanese national health insurance system. int j technol assess health care. 2019; 35 (6) ,452 – 460. doi: 10.1017/s0266462319000060 66.guideline for preparing cost-effectiveness evaluation to the central social insurance medical council [internet]. core2 health.2019, [cited 17 aug 2021]. available from: https://c2h.niph.go.jp/tools/guideline/guideline_en.pdf 67.kristensen fb, husereau d, huić m, drummond m, berger ml, bond k, et al. identifying the need for good practices in health technology assessment: summary of the ispor hta council working group report on good practices in hta. value health. 2019;22(1):13-20. doi: 10.1016/j.jval.2018.08.010 68.sakamoto h, rahman m, nomura s, okamoto e, koike s. et al. japan health system review [internet]. world health organization. regional office for south-east asia. 2018, [cited 2020 oct 28]. available from: https://apps.who.int/iris/handle/10665/259941 69.zhang y, tang w, zhang x, zhang y, zhang l. national health insurance development in china from 2004 to 2011: coverage versus benefits. plos one. 2015; 10(5): e0124995. doi:10.1371/ journal.pone.0124995 70.zhao k, li x, guo w, xiao x. coming rapidly of age: health technology assessment in china [internet]. 2018, [cited 2020 oct 28]. available from: https://globalforum.diaglobal.org/issue/may-2 018/coming-rapidly-of-age-health-technology-assessment-inchina/ 71.zhen x, sun x, dong h. health technology assessment and its use in drug policies in china. value health. 2018;15:138–148. doi: 10.1016/j.vhri.2018.01.010 72.chen y, he y, chi x, wei y, shi l. development of health technology assessment in china: new challenges. biosci trends. 2018;12(2):102–108. doi: 10.5582/bst.2018.01038 73. highsmith mj, kahle jt, wernke mm, carey sl, miro rm, lura dj, sutton bs. 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 74.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, 2015, [cited 2021 july 20]. available from: https://www.hassante.fr/upload/docs/evamed/cepp-4969_3c100%20cleg%20_01_decembre_2015_(4969)_avis.pdf 75.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, 2016, [cited 2021 july 20]. available from: https://www.has-sante.fr/upload/docs/evamed/cepp5106_kenevo_20%20septembre_2016_(5106)_avis.pdf https://doi.org/10.33137/cpoj.v4i2.35298 http://www.aotmit.gov.pl/ https://en.wikipedia.org/wiki/list_of_countries_by_gdp_(nominal) https://www.nice.org.uk/about/what-we-do/our-programmes/nice-guidance/nice-technology-appraisal-guidance https://www.nice.org.uk/about/what-we-do/our-programmes/nice-guidance/nice-technology-appraisal-guidance https://www.crd.york.ac.uk/crdweb/printpdf.php?accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e&accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e https://www.crd.york.ac.uk/crdweb/printpdf.php?accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e&accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e https://www.crd.york.ac.uk/crdweb/printpdf.php?accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e&accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e https://www.crd.york.ac.uk/crdweb/printpdf.php?accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e&accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e https://www.crd.york.ac.uk/crdweb/printpdf.php?accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e&accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e https://www.crd.york.ac.uk/crdweb/printpdf.php?accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e&accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e https://www.crd.york.ac.uk/crdweb/printpdf.php?accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e&accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e https://www.crd.york.ac.uk/crdweb/printpdf.php?accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e&accessionnumber=32013000467&copyright=health+technology+assessment+%28hta%29+database%3cbr+%2f%3ecopyright+%26copy%3b+2014+nhs+quality+improvement+scotland+%28nhs+qis%29%3cbr+%2f%3e https://www.healthtechnology.wales/about/our-appraisal-process https://www.globalhealthpr.com/serivices/northern-ireland/ 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 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, phillips s, groer s, highsmith mj. a review of clinical outcome assessment instruments for gait, balance, and fall risk in persons with lower extremity amputation. top geriatr rehabil. 2014;30(1):70–6. doi: 10.1097/tgr. 0b013e318215cbb3 5.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 6.ganz da, bao y, shekelle pg, rubenstein lz. will my patient fall? jama. 2007;297(1):77–86. doi: 10.1001/jama.297.1.77 7.latlief g, elnitsky c, kent r. lower extremity amputation. in: batmangelich s, cristian a, editors. physical medicine and rehabilitation patient-centered care. new york, ny: demos medical publishing; 2014. p. 409. 8.miller wc, speechley m, deathe ab. 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 9.moore ds, ellis r. measurement of fall-related psychological constructs among independent-living older adults: a review of the research literature. aging ment health. 2008;12(6):684–99. doi: 10.1080/13607860802148855 10.suckow bd, goodney pp, nolan bw, veeraswamy rk, gallagher p, cronenwett jl, et al. domains that determine quality of life in vascular amputees. ann vasc surg. 2015;29(4):722–30. doi: 10.1016/j.avsg.2014.12.005 11.deathe ab, miller wc, speechley m. the status of outcome measurement in amputee rehabilitation in canada. arch phys med rehabil. 2002;83(7):912–8. doi: 10.1053/apmr.2002.33221 12.miller wc, deathe ab. a prospective study examining balance confidence among individuals with lower limb amputation. disabil rehabil. 2004;26(14–15):875–81. doi: 10.1080/ 09638280410001708887 13.bandura a. self-efficacy: toward a unifying theory of behavioral change. psychol rev. 1977;84(2):191–215. doi: 10.1037/0033295x.84.2.191 14.bandura a. social cognitive theory of self-regulation. organ behav hum decis process. 1991;50(2):248–87. doi: 10.1016/ 0749-5978(91)90022-l 15.bandura a. self-efficacy mechanism in human agency. am psychol. 1982;37(2):122–47. doi: 10.1037/0003-066x.37.2.122 16.danks ka, pohlig rt, roos m, wright tr, reisman ds. relationship between walking capacity, biopsychosocial factors, self-efficacy, and walking activity in persons poststroke. j neurol phys ther. 2016;40(4):232–8. doi: 10.1097/npt. 0000000000000143 17.harrison al. the influence of pathology, pain, balance, and selfefficacy on function in women with osteoarthritis of the knee. phys ther. 2004;84(9):822–31. doi: 10.1093/ptj/84.9.822 18.maly mr, costigan pa, olney sj. contribution of psychosocial and mechanical variables to physical performance measures in knee osteoarthritis. phys ther. 2005;85(12):1318–28. doi: 10.1093/ptj/85.12.1318 19.collins tc, lunos s, ahluwalia js. self-efficacy is associated with walking ability in persons with diabetes mellitus and peripheral arterial disease. vasc med. 2010;15(3):189–95. doi: 10.1177/1358863x10362604 20.motl rw, balto jm, ensari i, hubbard ea. self-efficacy, and walking performance in persons with multiple sclerosis. j neurol phys ther. 2017;41(2):114–8. doi: 10.1097/npt. 0000000000000172 21.morimoto ss, kanellopoulos t, alexopoulos gs. cognitive impairment in depressed older adults: implications for prognosis and treatment. psychiatr ann. 2014;44(3):138. doi: 10.3928/00485713-20140306-05 22.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):626–35. doi: 10.1093/ptj/85.7.626 23.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 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 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 use. j rehabil res dev. 2008; 45:15–30. doi:10.1682/jrrd.2006.11.0147 2.nolan l, wit a, dudziñski k, lees a, lake m, wychowañski m. adjustments in gait symmetry with walking speed in trans-femoral and trans-tibial amputees. gait posture. 2003; 17:142–51. doi:10.1016/s0966-6362(02)00066-8 https://doi.org/10.33137/cpoj.v5i1.36223 7 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 3.parker j, mountain g, hammerton j. a review of the evidence underpinning the use of visual and auditory feedback for computer technology in post-stroke upper-limb rehabilitation. disabil rehabil assist technol. 2011; 6:465–72. doi:10.3109/17483107.2011. 556209 4.escamilla-nunez r, michelini a, andrysek j. biofeedback systems for gait rehabilitation of individuals with lower-limb amputation: a systematic review. sensors. 2020; 20:1628. doi:10.3390/s20061628 5.van gelder lma, barnes a, wheat js, heller bw. the use of biofeedback for gait retraining: a mapping review. clin biomech. 2018; 59:159–66. doi:10.1016/j.clinbiomech.2018.09.020 6.sigrist r, rauter g, riener r, wolf p. augmented visual, auditory, haptic, and multimodal feedback in motor learning: a review. psychon bull rev. 2013; 20:21–53. doi:10.3758/s13423012-0333-8 7.sienko kh, seidler rd, carender wj, goodworth ad, whitney sl, peterka rj. potential mechanisms of sensory augmentation systems on human balance control. front neurol. 2018; 9. doi:10.3389/fneur.2018.00944 8.bridenbaugh sa, kressig rw. laboratory review: the role of gait analysis in seniors’ mobility and fall prevention. gerontology. 2011; 57:256–64. doi:10.1159/000322194 9.moumdjian l, buhmann j, willems i, feys p, leman m. entrainment and synchronization to auditory stimuli during walking in healthy and neurological populations: a methodological systematic review. front hum neurosci. 2018; 12. doi:10.3389/fnhum.2018.00263 10.ghai s, ghai i, effenberg ao. effect of rhythmic auditory cueing on aging gait: a systematic review and meta-analysis. aging dis. 2018; 9:901. doi:10.14336/ad.2017.1031 11.chamorro-moriana g, moreno a, sevillano j. technologybased feedback and its efficacy in improving gait parameters in patients with abnormal gait: a systematic review. sensors. 2018; 18:142. doi:10.3390/s18010142 12.wright rl, bevins jw, pratt d, sackley cm, wing am. metronome cueing of walking reduces gait variability after a cerebellar stroke. front neurol. 2016; 7:5–10. doi:10.3389/fneur. 2016.00084 13.nascimento lr, de oliveira cq, ada l, michaelsen sm, teixeira-salmela lf. walking training with cueing of cadence improves walking speed and stride length after stroke more than walking training alone: a systematic review. j physiother. 2015; 61:10–5. doi:10.1016/j.jphys.2014.11.015 14.sohliya l, thomas r. rhythmic auditory stimulation for gait training in persons with unilateral transtibial amputation: a randomized-controlled trial. ann phys rehabil med. 2018; 61:e377. doi:10.1016/j.rehab.2018.05.875 15.hesse s, konrad m, uhlenbrock d. treadmill walking with partial body weight support versus floor walking in hemiparetic subjects. arch phys med rehabil. 1999; 80:421–7. doi:10.1016/s00039993(99)90279-4 16.brandt a, huang hh. effects of extended stance time on a powered knee prosthesis and gait symmetry on the lateral control of balance during walking in individuals with unilateral amputation. j neuroeng rehabil. 2019; 16:1–12. doi:10.1186/s12984-0190625-6 17.mori h, tamari m. predicative factors of the effect of body weight support treadmill training in stroke hemiparesis patients. j phys ther sci. 2020; 32:550–3. doi:10.1589/jpts.32.550 18.crea s, edin bb, knaepen k, meeusen r, vitiello n. timediscrete vibrotactile feedback contributes to improved gait symmetry in patients with lower limb amputations: case series. phys ther. 2017; 97:198–207. doi:10.2522/ptj.20150441 19.sharma a, torres-moreno r, zabjek k, andrysek j. toward an artificial sensory feedback system for prosthetic mobility rehabilitation: examination of sensorimotor responses. j rehabil res dev. 2014; 51:907–18. doi:10.1682/jrrd.2013.07.0164 20.sharma a, leineweber mj, andrysek j. effects of cognitive load and prosthetic liner on volitional response times to vibrotactile feedback. j rehabil res dev. 2016; 53:473–82. doi: 10.1682/jrrd.2016.04.0060 21.roerdink m, bank pjm, peper cle, beek pj. walking to the beat of different drums: practical implications for the use of acoustic rhythms in gait rehabilitation. gait posture. 2011; 33:690–4. doi:10.1016/j.gaitpost.2011.03.001 22.yu l, zhang q, hu c, huang q, ye m, li d. effects of different frequencies of rhythmic auditory cueing on the stride length, cadence, and gait speed in healthy young females. j phys ther sci. 2015; 27:485–7. doi:10.1589/jpts.27.485 23.smith jd, martin pe. walking patterns change rapidly following asymmetrical lower extremity loading. hum movement sci. 2007; 26:412–25. doi:10.1016/j.humov.2006.12.001 24.kodesh e, kafri m, dar g, dickstein r. walking speed, unilateral leg loading, and step symmetry in young adults. gait posture. 2012; 35:66–9. doi:10.1016/j.gaitpost.2011.08.008. 25.ramakrishnan t, lahiff c, reed kb. comparing gait with multiple physical asymmetries using consolidated metrics. front neurorobot. 2018; 12:1–12. doi:10.3389/fnbot.2018.00002 26.van melick n, meddeler bm, hoogeboom tj, nijhuis-van der sanden mwg, van cingel reh. how to determine leg dominance: the agreement between self-reported and observed performance in healthy adults. plos one. 2017; 12:e0189876. doi:10.1371/journal.pone.0189876 27.collins td, ghoussayni sn, ewins dj, kent ja. a six degreesof-freedom marker set for gait analysis: repeatability and 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 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 movaid 13 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 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. small sample research designs for evidence-based rehabilitation: issues and methods. arch phys med rehabil. 2012; 93(8 suppl), s111–s116. doi: 10.1016/j.apmr.2011.12.017 3.chen c, hanson m, chaturvedi r, mattke s, hillestad r, liu hh. economic benefits of microprocessor controlled prosthetic knees: a modeling study. j neuroeng rehabil. 2018; 15(suppl 1):62. doi:10.1186/s12984-018-0405-8 4.koehler-mcnicholas sr, nickel ea, barrons k, blaharski ke, dellamano ca, ray sf, et al. mechanical and dynamic characterization of prosthetic feet for high activity users during weighted and unweighted walking. plos one. 2018; 13(9): e0202884. doi:10.1371/journal.pone.0202884 5.catalyst ne. what is value-based healthcare? nejm catalyst. 2017;1;3(1). 6.kaplan rs, porter me. the big idea: how to solve the cost crisis in health care [internet]. harvard business review. brighton, ma. 2011; [cited 11 april 2022]. available from: https://hbr.org/2011/09/how-to-solve-the-cost-crisis-in-health-care 7.mattison 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 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. [cited 2021 feb 10]. available from: https://en.wikipedia.org/wiki/futures_studies#futures_techniques 2. stevens h. why outbreaks like coronavirus spread exponentially, and how to “flatten the curve.” [internet]. washington post, 2020; [cited 2021 feb 10]; available from: https://www.washingtonpost.com/graphics/2020/world/coronasimulator/ 3.hunter b. tipping points in social networks [internet]. stanford university. [cited 2021 feb 10]. available from: https://web.stanford.edu/class/symbsys205/tipping_point.html 4.scientists four future international [internet]. scientists4future.org [cited 2021 feb 10]. available from: http://scientists4future.org/weare/facts/ 5.böcker c. berufsbildung 4.0 – fachkräftequalifikationen und kompetenzen für die digitalisierte arbeit von morgen: der ausbildungsberuf „orthopädietechnik-mechaniker/-in“ im screening [vocational training and education 4.0 skilled labour qualifications and competences for the digitalised work of tomorrow: the vocational training occupation "certified prosthetist/orthotist" in screening] [internet]. german federal institute for vocational education and training; 2020; [cited 2021 feb 10]. available from: https://www.bibb.de/veroeffentlichungen/de/publication/show/1049 4 6.top 3d scanning software: photogrammetry, laser and light scanning, and scanning apps for your phone [internet]. sculpteo. [cited 2021 feb 10]. available from: https://www.sculpteo.com/en/3d-learning-hub/3d-printingsoftware/3d-scanner-app/ 7.body measurement technology at your fingertips [internet]. techmed3d. [cited 2021 feb 10]. available from: https://techmed3d.com/products/3dsizeme/ 8.the app [internet]. comb o&p. [cited 2021 feb 10]. available from: https://www.combscan.com/the-comb-app 9.tate ts. unlocking the potential for cad/cam in today’s o&p [internet]. the academy today. 2013; [cited 2021 feb 10]. available from: http://digital.publicationprinters.com/publication/index.php?m=215 80&i=559112&p=11&pp=1&ver=html5 10.mecuris solution platform-your digital workshop [internet]. mecuris. [cited 2021 feb 10]. available from: https://www.mecuris.com/ 11.the pandofit solution [internet]. prosfit. [cited 2021 feb 10]. available from: https://prosfit.com 12.discover the full potential of mass-customised 3d printed orthotic devices [internet]. spentys. [cited 2021 feb 10]. available from: https://www.spentys.com/products 13.xkelet [internet]. [cited 2021 feb 10]. available from: http://www.xkelet.com/en 14.3d printing: patients benefit from custom orthoses [internet]. ottobock.com. 2018; [cited 2021 feb 10]. available from: https://www.ottobock.com/en/newsroom/news/3d-printingpatients-benefit-from-custom-orthoses.html 15.össur acquires scanning and design technology from standard cyborg [internet]. ossur. 2020; [cited 2021 feb 10]. available from: https://www.ossur.com/en-us/aboutossur/newsroom/ossur-acquires-scanning-and-design-technologyfrom-standard-cyborg 16.weiser a. economic and ecological sustainability assessment of the digitalization of orthopedic technology using 3d printing focusing on positioning pediatric splints [undergraduate thesis]. hochschule münchen; 2020. 17.kienzle c, schäfer m. integration of additive manufacturing processes in orthopedic technology fitting routine. orthopädie technik. 2018;(5). 18.verlängerte werkbank [extended workbench] [internet]. nowecor. [cited 2021 feb 10]. available from: https://www.nowecor.de/unternehmen/werkbank 19.additiveamerica [internet]. [cited 2021 feb 10]. available from: http://www.additiveamerica.com 20.otto jp. the perfect wave? central fabrication rides the tide as o&p evolves [internet]. the o&p edge. 2018; [cited 2021 feb 10]. available from: https://opedge.com/articles/viewarticle/201808-01/the-perfect-wave-central-fabrication-rides-the-tide-as-opevolves 21.technical considerations for additive manufactured medical devices [internet]. food and drug administration. 2017; [cited 2021 feb 10]; available from: https://www.fda.gov/media/97633/download 22.definitions for personalized medical devices [internet]. international medical device regulators forum. 2018; [cited 2021 feb 10]; available from: http://www.imdrf.org/docs/imdrf/final/technical/imdrf-tech-181018pmd-definitions-n49.pdf 23.custom device exemption guidance for industry and food and drug administration staff [internet]. food and drug administration. 2014; [cited 2021 feb 10]. available from: https://www.fda.gov/media/89897/download 24.mdcg 2021-03 questions and answers on custom-made devices & considerations on adaptable medical devices and patient-matched medical devices [internet]. medical device coordination group. 2021; [cited 2021 may 25]. available from: https://ec.europa.eu/health/sites/default/files/md_sector/docs/mdc g_2021-3_en.pdf 25.digital process chains in industrial manufacturing for medical devices [internet]. vdithe association of german engineers. 2021; [cited 2021 feb 10]. available from: https://www.vdi.de/richtlinien/details/vdi-5705-blatt-1-digitaleprozessketten-in-der-industriellen-medizintechnik-herstellung-vonsonderanfertigungen 26.medical devices regulations [internet]. canadian minister of justice. 2019; [cited 2021 feb 10]. available from: https://lawslois.justice.gc.ca/pdf/sor-98-282.pdf 27.guidance for health care professionals on special access and custom-made medical devices [internet]. canadian minister of health. 2016; [cited 2021 feb 10]. available from: https://doi.org/10.33137/cpoj.v4i2.36349 https://en.wikipedia.org/wiki/futures_studies#futures_techniques https://www.washingtonpost.com/graphics/2020/world/corona-simulator/ https://www.washingtonpost.com/graphics/2020/world/corona-simulator/ https://web.stanford.edu/class/symbsys205/tipping_point.html http://scientists4future.org/we-are/facts/ http://scientists4future.org/we-are/facts/ https://www.bibb.de/veroeffentlichungen/de/publication/show/10494 https://www.bibb.de/veroeffentlichungen/de/publication/show/10494 https://www.sculpteo.com/en/3d-learning-hub/3d-printing-software/3d-scanner-app/ https://www.sculpteo.com/en/3d-learning-hub/3d-printing-software/3d-scanner-app/ https://techmed3d.com/products/3dsizeme/ https://www.combscan.com/the-comb-app http://digital.publicationprinters.com/publication/index.php?m=21580&i=559112&p=11&pp=1&ver=html5 http://digital.publicationprinters.com/publication/index.php?m=21580&i=559112&p=11&pp=1&ver=html5 https://www.mecuris.com/ https://prosfit.com/ https://www.spentys.com/products http://www.xkelet.com/en https://www.ottobock.com/en/newsroom/news/3d-printing-patients-benefit-from-custom-orthoses.html https://www.ottobock.com/en/newsroom/news/3d-printing-patients-benefit-from-custom-orthoses.html https://www.ossur.com/en-us/about-ossur/newsroom/ossur-acquires-scanning-and-design-technology-from-standard-cyborg https://www.ossur.com/en-us/about-ossur/newsroom/ossur-acquires-scanning-and-design-technology-from-standard-cyborg https://www.ossur.com/en-us/about-ossur/newsroom/ossur-acquires-scanning-and-design-technology-from-standard-cyborg https://www.nowecor.de/unternehmen/werkbank http://www.additiveamerica.com/ https://opedge.com/articles/viewarticle/2018-08-01/the-perfect-wave-central-fabrication-rides-the-tide-as-op-evolves https://opedge.com/articles/viewarticle/2018-08-01/the-perfect-wave-central-fabrication-rides-the-tide-as-op-evolves https://opedge.com/articles/viewarticle/2018-08-01/the-perfect-wave-central-fabrication-rides-the-tide-as-op-evolves https://www.fda.gov/media/97633/download http://www.imdrf.org/docs/imdrf/final/technical/imdrf-tech-181018-pmd-definitions-n49.pdf http://www.imdrf.org/docs/imdrf/final/technical/imdrf-tech-181018-pmd-definitions-n49.pdf https://www.fda.gov/media/89897/download https://ec.europa.eu/health/sites/default/files/md_sector/docs/mdcg_2021-3_en.pdf https://ec.europa.eu/health/sites/default/files/md_sector/docs/mdcg_2021-3_en.pdf https://www.vdi.de/richtlinien/details/vdi-5705-blatt-1-digitale-prozessketten-in-der-industriellen-medizintechnik-herstellung-von-sonderanfertigungen https://www.vdi.de/richtlinien/details/vdi-5705-blatt-1-digitale-prozessketten-in-der-industriellen-medizintechnik-herstellung-von-sonderanfertigungen https://www.vdi.de/richtlinien/details/vdi-5705-blatt-1-digitale-prozessketten-in-der-industriellen-medizintechnik-herstellung-von-sonderanfertigungen https://laws-lois.justice.gc.ca/pdf/sor-98-282.pdf https://laws-lois.justice.gc.ca/pdf/sor-98-282.pdf 9 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 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 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 critical because the profession needs ownership and unification to move forward. acknowledgements the authors wish to thank denise caruso, bs for her editorial efforts. declaration of conflicting interests the authors declare there are no conflicts of interest. sources of support the authors declare no sources of external support for this project. references 1.what is the value of values-based healthcare? innovations in care delivery [internet]. new england journal of medicine catalyst. https://doi.org/10.33137/cpoj.v4i2.36673 6 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 2017, [cited 2021 may 15]. available from: https://catalyst.nejm.org/doi/full/10.1056/cat.17.0558 2.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 perspective. engineering. 2020; (6)1258-1266. doi:10.1016/j.eng.2020.07.019 3.andrysek j, christensen j, dupuis a. factors influencing evidence-based practice in prosthetics and orthotics. prosthet orthot int. 2011; 35(1)30-38. doi: 10.1177/0309364610389353 4.ramstad n, brodtkorb th. considerations for developing an evidenced-based practice in orthotics and prosthetics. prosthet orthot int. 2008; 32(1) 93–102. doi: 10.1080/03093640701838190 5.davanzo je, el-gamil a, heath s, pal s, li j, luu p, et al. projecting the adequacy of workforce supply to meet patient demand analysis of the orthotics and prosthetics (o&p) profession [internet]. vienna, va: llc. 2015; [cited 2021 may 15]. available from: https://iiofoandp.org/wpcontent/uploads/2018/04/2015_work_study.pdf 6.heinemann aw, fisher jr wp, gershon r. improving health care quality with outcomes management. j prosthet orthot. 2006;18(6):46-50. 7.stevens pm. barriers to the implementation of evidence‐based practice in orthotics and prosthetics. j prosthet. orthot. 2011; 23(1): 34‐39. doi: 10.1097/jpo.0b013e3182064d29 8.cherian lt, pine sg, scott gt. white paper: value-based safe harbors and exceptions to the anti-kickback statute and stark law [internet]. k&l gates, [cited 2021 may 8]. available from: https://www.klgates.com/white-paper-value-based-safe-harborsand-exceptions-to-the-anti-kickback-statute-and-stark-law-2-242021 9.mccoy lg, nagaraj s, morgado f, harish v, das s, celi la. what do medical students actually need to know about artificial intelligence? npj digit. med. 2020; (3) 86. doi:10.1038/s41746020-0294-7 10.practice analysis for orthotics and prosthetics [internet]. american board for certification in orthotics, prosthetics and pedorthics, inc. alexandria, va: 2015; [cited 2021 may 16]. available from: https://www.abcop.org/publication/practitionerpractice-analysis 11.taken from caahep o&p standards, appendix b [internet]. national commission on orthotic and prosthetic education, core curriculum guide master’s level. 2017; [cited 2021 may 15]. available from: http://ncope.com/assets/pdf/core_guide_for_op.pdf?20171121 12.farhan m, zhanzi j, wang jz, bray p, burns j, tegan lc. comparison of 3d scanning versus traditional methods of capturing foot and ankle morphology for the fabrication of orthoses: a systematic review. j foot ankle res. 2021; (14)2 doi:10.1186/s13047-020-00442-8 13.thimbleby h. technology and the future of healthcare. j pub health res. 2013; 2(3), e28. doi:10.4081/jphr.2013.e28 14.köhler p, lindh l, netz p. comparison of cad-cam and hand made sockets for ptb prostheses. prosth orthot int. 1989; (13) 1924: doi: 10.3109/03093648909079405 15. orthotist / prosthetist programs [internet]. national commission on orthotic and prosthetic education, [cited 2021 july 24]. available from: https://ncope.org/index.php/home-pagev2/academic-programs/accredited-practitioner-programs/ 16.o&p education summit: forecasting the future final report [internet]. new orleans, la; 2005; [cited 2021 may 26]. available from: https://ncope.com/summit/pdf/edsummit_final_report.pdf 17.hovorka cf, shurr dg, bozik ds. the concept of an entry-level interdisciplinary graduate degree preparing orthotists for the new millennium part 1: history of orthotic and prosthetic education. j prosthet. orthot. 2002; (14)2:51-57. doi:10.1097/00008526200206000-00006 18.teamwork and collaborative decision-making crucial to health care of the future [internet]. robert wood johnson foundation. 2011; [cited 2021 may 15]. available from: https://www.rwjf.org/en/library/articles-andnews/2011/11/teamwork-and-collaborative-decision-makingcrucial-to-health-car.html 19.elwyn g, edwards a, thompson r. shared decision making in health care: achieving evidence-based patient choice. 3rd ed. oxford university press: oxford, united kingdom; 2016. doi:10.1093/acprof:oso/9780198723448.001.0001 20.framework for action on interprofessional education & collaborative practice [internet]. department of human resources for health: geneva, switzerland; world health organization. 2010; [cited 2021 may 26]. available from: http://apps.who.int/iris/bitstream/handle/10665/70185/who_hrh _hpn_10.3_eng.pdf;jsessionid=53386e401ae3bc570e9dc0505 647eff5?sequence=1 21.zechariah s, ansa be, johnson se, gates am, deleo g. interprofessional education and collaboration in healthcare: an exploratory study of the perspectives of medical students in the united states. healthcare. 2019;7(4):117 doi: 10.3390/healthcare7040117 22.blue av, chesluk bj, conforti ln, holmboe es. assessment and evaluation in interprofessional education: exploring the field. j allied health. 2015;44(2):73-82. pmid: 26046114 23.surface c, brinkmann jt. what are clinical supervisors looking for in residents. characteristics of effective clinical learners [internet]. o&p edge, 2020; [cited 2021 may 26] available from: https://opedge.com/articles/viewarticle/2020-03-01/what-areclinical-supervisors-looking-for-in-residents 24.postema k, williams ae. a toolkit for prosthetists and orthotists to facilitate progress in professional communication over the next 50years. prosthet orthot int. 2020 44(6); 408–415. doi: 10.1177/0309364620962325 25.rosenstein di, joseph lp, mackenzie lj, wyden r. professional encroachment: a comparison of the emergence of denturists in canada and oregon. am j public health. 1980;70(6):614-618. doi:10.2105/ajph.70.6.614 26.rosenstein di, empey g, chiodo gt, phillips d. the effects of denturism on denture prices. am j public health. 1985; 75(6) 6712. doi: 10.2105/ajph.75.6.671 27.okuda bc, tabbaa s, edmonds m, toubouti y, saltaji h. direct to consumer orthodontics: exploring patient demographic trends and preferences. am. j. orthod. dentofacial. orthop. 2021;159(2):210-216.e2. doi: 10.1016/j.ajodo.2019.12.024 https://doi.org/10.33137/cpoj.v4i2.36673 https://catalyst.nejm.org/doi/full/10.1056/cat.17.0558 https://iiofoandp.org/wp-content/uploads/2018/04/2015_work_study.pdf https://iiofoandp.org/wp-content/uploads/2018/04/2015_work_study.pdf https://www.klgates.com/white-paper-value-based-safe-harbors-and-exceptions-to-the-anti-kickback-statute-and-stark-law-2-24-2021 https://www.klgates.com/white-paper-value-based-safe-harbors-and-exceptions-to-the-anti-kickback-statute-and-stark-law-2-24-2021 https://www.klgates.com/white-paper-value-based-safe-harbors-and-exceptions-to-the-anti-kickback-statute-and-stark-law-2-24-2021 https://www.abcop.org/publication/practitioner-practice-analysis https://www.abcop.org/publication/practitioner-practice-analysis http://ncope.com/assets/pdf/core_guide_for_op.pdf?20171121 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://ncope.com/summit/pdf/edsummit_final_report.pdf https://www.rwjf.org/en/library/articles-and-news/2011/11/teamwork-and-collaborative-decision-making-crucial-to-health-car.html https://www.rwjf.org/en/library/articles-and-news/2011/11/teamwork-and-collaborative-decision-making-crucial-to-health-car.html https://www.rwjf.org/en/library/articles-and-news/2011/11/teamwork-and-collaborative-decision-making-crucial-to-health-car.html http://apps.who.int/iris/bitstream/handle/10665/70185/who_hrh_hpn_10.3_eng.pdf;jsessionid=53386e401ae3bc570e9dc0505647eff5?sequence=1 http://apps.who.int/iris/bitstream/handle/10665/70185/who_hrh_hpn_10.3_eng.pdf;jsessionid=53386e401ae3bc570e9dc0505647eff5?sequence=1 http://apps.who.int/iris/bitstream/handle/10665/70185/who_hrh_hpn_10.3_eng.pdf;jsessionid=53386e401ae3bc570e9dc0505647eff5?sequence=1 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 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 patient-reported outcome. acta orthop. 2020;91(4):464–70. doi:10.1080/17453674.2020.1756101 3.paterno 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):1996–2010. doi:10.1109/tbme.2017.2775100 4.madsen u, hommel a, berthelsen c, bååth c. systematic review describing the effect of early mobilisation after dysvascular major lower limb amputations. j. clin. nurs. 2017;26(21–22). doi:10.1111/jocn.13716 5.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):125–37. doi:10.21300/18.23.2016.125 6.sauter cn, pezzin le, dillingham tr. functional outcomes of persons who underwent dysvascular lower extremity amputations. am j phys med rehabil. 2013; 92(4):287–96. doi:10.1097/phm. 0b013e31827d620d 7.hagberg k, brånemark r. consequences of non-vascular transfemoral amputation. prosthetics orthot int. 2001;25(3):186–94. doi:10.1080/03093640108726601 8.össur. direct socket material kit [internet]. [cited 2021 may 30] available from: https://www.ossur.com/enus/prosthetics/sockets/direct-socket-material-kit https://doi.org/10.33137/cpoj.v4i1.36065 https://www.ossur.com/en-us/prosthetics/sockets/direct-socket-material-kit https://www.ossur.com/en-us/prosthetics/sockets/direct-socket-material-kit 11 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 9.eneroth m, apelqvist j, troëng t, persson bm. operations, total hospital stay and costs of critical leg ischemia: a population-based longitudinal outcome study of 321 patients. acta orthop scand. 1996;67(5):459–65. doi:10.3109/17453679608996668 10. söderberg b, hagberg k, mattsson l, larsson j, örneholm h, roubert a, et.al. swedeamp: swedish lower limb amputations register. 2018 report [internet]. 2019. [cited 2021 may 30]. available from: https://swedeamp.com/wpcontent/uploads/2019/09/arsrapport-2018-final_190409.pdf 11.sparg. a survey of the lower limb amputee population in scotland, 2008 [internet]. [cited 2021 may 30]. available from: http://www.knowledge.scot.nhs.uk/media/clt/resourceuploads/4 093845/ed2d2db3-ca6a-442d-a324-10dcc431707d.pdf 12.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 13.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 14.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 15.rouhani n, esfandiari e, babaee t, khosravi m, moradi v, balouchkayvan b, et al. the comprehensive lower limb amputee socket survey: reliability and validity of the persian version. prosthet orthot int. 2020. doi:10.1177/0309364620958526 16.muller md. atlas of amputations and limb deficiencies: surgical, prosthetic, and rehabilitation principles. 4th ed. krajbich ji, pinzur ms, potter b, stevens pm, editors. american academy of orthopaedic surgeons; 2016. chapter 43. 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. doi:10.1177/0309364620913459 18.fatone s, caldwell r. northwestern university flexible subischial vacuum socket for persons with transfemoral amputation-part 1. prosthetics orthot int. 2017;41(3):237–45. doi:10.1177/0309364616685229 19.kahle jt, klenow td, sampson wj, highsmith mj. the effect of transfemoral interface design on gait speed and risk of falls. technol innov. 2017;18(813):167–73. doi:10.21300/18.23.2016.167 20.fatone s, caldwell r. northwestern university flexible subischial vacuum socket for persons with transfemoral amputation. prosthetics orthot int. 2017;41(3):246–50. doi:10.1177/ 0309364616685230 21.miller t, paul r, forthofer m, wurdeman sr, affairs s, clinic h, et al. impact of time to receipt of prosthesis on total healthcare costs 12 months post-amputation taavy. am j phys med rehabil. 2020;99(11):1026–31. doi:10.1097/phm.0000000000001473 22.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 23.össur-academy. direct socket system by össur hf, 2020. [cited 2021 may 30]. available from: https://www.youtube.com/watch?v=okljzjkqg3m&t=4s 24.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 25.össur hf. direct socket tf [internet]. 2020-10-12. 2020. [cited 2020 aug 25]. available from: https://www.ossur.com/enus/prosthetics/sockets/direct-socket-tf 26.össur-academy. direct socket tfsummary [internet]. 2021. [cited 2020 aug 25]. available from: https://www.youtube.com/watch?v=-fvvfqjgxjo 27.marable wr, smith c, sigurjónsson bþ, atlason if, johannesson ga. transfemoral socket fabrication method using direct casting: outcomes regarding patient satisfaction with device and services. can prosthet orthot j. 2020;3(2). doi:10.33137/cpoj.v3i2.34672 28.bosmans j, suurmeijer t, hulsink m, van der schans c, geertzen j, dijkstra p. amputation, phantom pain and subjective well-being: a qualitative study. int j rehabil res. 2007;30(1):1–8. doi:10.1097/mrr.0b013e328012c953 29.hagberg k, häggström e, uden m, brånemark 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 30.meulenbelt h, geertzen j, jonkman m, dijkstra p. skin problems of the stump in lower limb amputees: 1. a clinical study. acta derm venereol. 2011;91(2):173–7. doi:10.2340/000155551040 31.gaunaurd i, spaulding s, amtmann d, salem r, gailey r, morgan s, et al. use of and confidence administering outcome measures among clinical prosthetists: results from a national survey and mixed-methods training program. prosthet orthot int. 2015;39(4):314–21. doi:10.1177/0309364614532865 32.klenow, td pousett, b wening, j cabana, a anderson, c kaluf b. outcome measures toolkit summary: lower limb prosthetics. american academy of orthotists and prosthetists (aaop). 2020 [cited 2020 aug 25]. available from: https://www.oandp.org/page/llp_om_toolkit_summary 33. aaop 2020. outcome measures in patient care. j prosthetics orthot. 2020;32(2):20–4. doi: 10.1097/01.jpo.0000656440. 28478.ba 34.sions j, beisheim e, manal t, smith s, horne j, sarlo f. 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(7). doi:10.1016/j.apmr.2017.12.033 https://doi.org/10.33137/cpoj.v4i1.36065 https://swedeamp.com/wp-content/uploads/2019/09/arsrapport-2018-final_190409.pdf https://swedeamp.com/wp-content/uploads/2019/09/arsrapport-2018-final_190409.pdf http://www.knowledge.scot.nhs.uk/media/clt/resourceuploads/4093845/ed2d2db3-ca6a-442d-a324-10dcc431707d.pdf http://www.knowledge.scot.nhs.uk/media/clt/resourceuploads/4093845/ed2d2db3-ca6a-442d-a324-10dcc431707d.pdf https://www.youtube.com/watch?v=okljzjkqg3m&t=4s https://www.ossur.com/en-us/prosthetics/sockets/direct-socket-tf https://www.ossur.com/en-us/prosthetics/sockets/direct-socket-tf https://www.youtube.com/watch?v=-fvvfqjgxjo https://www.oandp.org/page/llp_om_toolkit_summary 12 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 35.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. agency for healthcare research and quality; 2018;ehc017-ef. available from:https://www.ncbi.nlm.nih.gov/books/nbk531517/table/ch2.ta b1 36.dillon m, major m, fatone s, kaluf b, balasanov y. predict the medicare functional classification level (k-level) using the amputee mobility predictor in people with unilateral transfemoral and transtibial amputation: a pilot study. prosthet orthot int. 2018;42(2):191 –197. doi:10.1177/0309364617706748 37.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 38.gailey r, kristal a, lucarevic j, harris s, applegate b, gaunaurd i. the development and internal consistency of the comprehensive lower limb amputee socket survey in active lower limb amputees. prosthet orthot int. 2019;43(1):80–87. doi:10.1177/0309364618791620 39.miller wc, speechley m, deathe ab. balance confidence among people with lower-limb amputations. phys ther. 2002;82(9):856–65. doi:10.1093/ptj/82.9.856 40.schoppen t, boonstra a, groothoff jw, de vries j, göeken lnh, eisma wh. the timed up and go test: reliability and validity in persons with unilateral lower limb amputation. arch phys med rehabil.1999;80(7):825–828.doi:10.1016/s0003-9993(99)902344 41.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):613–627. doi:10.1053/apmr.2002.32309 42.össur hf. the prosthetic rehabilitation outcomes application (pro app) [internet]. 2019. [cited 2020 aug 25]. available from: https://www.opsoutcomes.com/ops-proapp-privacy-notice 43. euroqol group. eq-5d [internet]. 2020. [cited 2020 aug 25]. available from: https://euroqol.org/eq-5d-instruments/ 44.craig bm, rand k. choice defines qalys: a us valuation of the eq-5d-5l. value health. 2018;21:s12. doi:10.1016/j.jval.2018.04.057 45.university of washington center on outcomes research in rehabilitation. prosthetic limb users survey of mobility (plusmtm) 12-item short form [internet]. version 1.2 – english (us). 2020. [cited 2020 may 30]. available from: http://plus-m.org/ 46.parry sw, steen n, galloway sr, kenny ra, bond j. falls and confidence related quality of life outcome measures in an older british cohort. postgrad med j. 2001;77(904):103–8. doi:10.1136/pmj.77.904.103 47.heinemann aw, bode rk, o’reilly c. development and measurement properties of the orthotics and prosthetics users’ survey (opus). prosthetics orthot int. 2003;27(3):191–206. doi:10.1080/03093640308726682 48.jarl g, heinemann aw, lindner hy, norling hermansson lm. cross-cultural validity and differential item functioning of the orthotics and prosthetics users’ survey with swedish and united states users of lower-limb prosthesis. arch phys med rehabil. 2015;96(9):1615–26. doi:10.1016/j.apmr.2015.03.003 49.cole mj, cumming j, golland n, hayes s, ostler c, scopes j, et al. bacpar tollbox of outcome measures version 2. british association of chartered physiotherapists in amputee rehabilitation. 2014. [cited 2020 may 30]. available from: https://bacpar.csp.org.uk/system/files/toolbox_version_2.pdf 50. gpower [internet]. 3.1.9.2. [cited 2020 may 30]. available from: https://www.psychologie.hhu.de/arbeitsgruppen/allgemeinepsychologie-und-arbeitspsychologie/gpower.html 51.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/dc081639 52.pohjolainen t, alaranta h, kärkäinen m. prosthetic use and functional and social outcome following major lower limb amputation. prosthet orthot int. 1990;14(2):75–9. doi:10.3109/ 03093649009080326 53.bates k, bolker b, walker s, christiensen rh, singmann h, dai b, et al. ime4 [internet]. package ́ lme4´. 2020. [cited 2020 may 30]. available from: https://github.com/lme4/lme4/ 54.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):227–36. doi:10.1177/ 0309364616637955 55.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 56.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):167–73. doi:10.21300/18.23.2016.167 57.hanspal r, fisher k, nieveen r. prosthetic socket fit comfort score. diability rehabil. 2003;25(22):1278–80. doi: 10.1080/ 09638280310001603983 58.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):1183–1189. 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. 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 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. 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 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; 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 references 1.who standards for prosthetics and orthotics [internet]. world health organization, 2017; [cited 2022, february 19]. available from: https://apps.who.int/iris/handle/10665/259209 2.triennial performance report; deputy for rehabilitation affairs [internet]. state welfare organization of iran, 2021; [cited 2022 july 12]. available from: https://media.behzisti.ir/d/2021/10/26/0/137702.pdf 3.annual visits of 70,000 people to red crescent rehabilitation centers/discount up to 50% to those in need [internet]. iranian red crescent society, 2021; [cited 2022 july 12]. available from: http://rcs.ir/news 4.peaco a, halsne e, hafner bj. assessing satisfaction with orthotic devices and services: a systematic literature review. j prosthet orthot. 2011;23(2):95-105. doi: 10.1097/jpo. 0b013e318217a0fe 5.bahadori m, ravangard r, aleviohammadzadeh k. the accreditation of hospitals in iran. iran j public health. 2015;44(2):295-6. 6.john j. patient satisfaction: the impact of past experience. j health care mark. 1992;12(3):56. 7.hallowell r. the relationships of customer satisfaction, customer loyalty, and profitability: an empirical study. int j serv ind. 1996. doi:10.1108/09564239610129931 8.cronin jr jj, brady mk, hult gt. assessing the effects of quality, value, and customer satisfaction on consumer behavioral intentions in service environments. j retail. 2000;76(2):193-218. doi: 10.1016/s0022-4359(00)00028-2 9.saxton jw. how to increase economic returns and reduce liability exposure: part 1--patient satisfaction as an economic tool. j med pract manage. 2001;17(3):142-4. 10.geertzen jh, gankema hg, groothoff jw, dijkstra pu. consumer satisfaction in prosthetics and orthotics facilities. prosthet orthot int. 2002;26(1):64-71. 11.xesfingi s, vozikis a. patient satisfaction with the healthcare system: assessing the impact of socio-economic and healthcare provision factors. bmc health serv res. 2016;16(1):1-7. doi: 10.1186/s12913-016-1327-4 12.adherence to long-term therapies: evidence for action [internet]. world health organization; 2003; [cited 2022, february 19]. available from: https://apps.who.int/iris/handle/10665/42682 13.joseph m, constant r, rickloff m, mezzio a, valdes k. a survey of client experiences with orthotics using the quest 2.0. j hand ther. 2018;31(4):538-43. doi: 10.1016/j.jht.2018.07.002 14.deruyter f. evaluating outcomes in assistive technology: do we understand the commitment? disabil rehabilitation. assist. technol. 1995;7(1):3-8. doi: 10.1080/10400435.1995.10132246 15.ghorbani f, kamyab m, azadinia f, hajiaghaei b. open-design collar vs. conventional philadelphia collar regarding user satisfaction and cervical range of motion in asymptomatic adults. am j phys med rehabil. 2016;95(4):291-9. doi: 10.1097/phm. 0000000000000374 16.thatipelli s, arun a, chung p, etemadi m, heller ja, kwiat d, et al. review of existing brace adherence monitoring methods to assess adherence. j prosthet orthot. 2016;28(4):126-35. doi: 10.1097/jpo.0000000000000106 17.barbosa cd, balp mm, kulich k, germain n, rofail d. a literature review to explore the link between treatment satisfaction and adherence, compliance, and persistence. patient prefer adherence. 2012;6:39. doi: 10.2147/ppa.s24752 18.valdes k, naughton n, algar l. linking icf components to outcome measures for orthotic intervention for cmc oa: a systematic review. j hand ther. 2016;29(4):396-404. doi: 10.1016/j.jht.2016.06.001 19.ghoseiri k, bahramian h. user satisfaction with orthotic and prosthetic devices and services of a single clinic. disabil rehabil. 2012;34(15):1328-32. doi: 10.3109/09638288.2011.641663 20.demers l, weiss-lambrou r, ska b. the quebec user evaluation of satisfaction with assistive technology (quest 2.0): an overview and recent progress. technol disabil. 2002;14(3):101105. doi: 10.3233/tad-2002-14304 21.gallagher p, maclachlan m. development and psychometric evaluation of the trinity amputation and prosthesis experience scales (tapes). rehabil psychol. 2000;45(2):130. doi: 10.1037/ 0090-5550.45.2.130 22.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(3):191-206. 23.hoda ms, allami m, asgari m. evaluation of users’ satisfaction with prosthesis and prosthetic services in tehran. iran j war public health. 2018;10(2):75-83. 24.bosmans j, geertzen j, dijkstra pu. consumer satisfaction with the services of prosthetics and orthotics facilities. prosthet orthot int. 2009;33(1):69-77. doi: 10.1080/03093640802403803 25.hadadi m, ghoseiri k, fardipour s, kashani rv, asadi f, asghari a. the persian version of satisfaction assessment module of orthotics and prosthetics users' survey. disabil health j. 2016;9(1):90-9. doi: 10.1016/j.dhjo.2015.08.010 26.scoring guide for the orthotics and prosthetics users survey [internet]. shirley ryan abilitylab (the rehabilitation institute of chicago); 2017. [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 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 clinicians. univ tor med. 2013; 90(3): 103-105 6.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 7.frossard l, ferrada l, quincey t, berg d. cost-effectiveness of transtibial bone-anchored prostheses using osseointegrated fixation. j prosthet orthot. 2021; doi: 10.1097/jpo.0000000000000372 8.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):318-327. doi: 10.1177/0309364617740239 9.bertram my, lauer ja, de joncheere k, edejer t, hutubessy r, kieny mp, et al. cost-effectiveness thresholds: pros and cons. bull world health organ. 2016; 94(12): 925-930. doi: 10.2471/blt.15.164418 10.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 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. 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 li n 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 il ly ; 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 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 y s 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 amputation: a systematic review. j am med dir ass. 2012; 13: 319-325. doi:10.1016/j.jamda.2010.12.097 4.norlyk a, martinsen b, hall e, haahr a. being in-between: the lived experience of becoming a prosthesis user following the loss of a leg. sage open. 2016; 6:1-9 doi:10.1177/2158244016671376 5.albert mv, deeny s, mccarthy c, valentin j, jayaraman a. monitoring daily function in persons with transfemoral amputations using a commercial activity monitor: a feasibility study. pmr. 2014; 6: 1120–1127. doi:10.1016/j.pmrj.2014.06.006 6.halsne eg, waddingham mg, hafner bj. long-term activity in and among persons with transfemoral amputation. j rehabil res dev. 2013; 50: 515–529. doi:10.1682/jrrd.2012.04.0066 7.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 8.zidarov d, swaine b, gauthier-gagnon c. life habits and prosthetic profile of persons with lower-limb amputation during rehabilitation and at 3-month follow-up. arch phys med rehabil. 2009; 90: 1953–1959. doi:10.1016/j.apmr.2009.06.011 9.gallagher p, o’donovan ma, doyle a, desmond d. environmental barriers, activity limitations and participation restrictions experienced by people with major limb amputation. prosthet orthot int. 2011; 35: 278–284. doi:10.1177/ 0309364611407108 10.van twillert s, stuive i, geertzen jh, postema k, lettinga at. functional performance, participation and autonomy after discharge from prosthetic rehabilitation: barriers, facilitators and outcomes. j rehabil med. 2014; 46: 915–923. doi:10.2340/ 16501977-1846 11.silva ad, furtado g, dos santos ip, da silva cb, caldas lr, bernardes ko, et al. functional capacity of elderly with lower-limb amputation after prosthesis rehabilitation: a longitudinal study. disabil rehabil: assist technol. 2019; 1-5. doi:10.1080/ 17483107.2019.1684581 12.dunne s, coffey l, gallagher p, desmond d, ryall n. beyond function: using assistive technologies following lower limb loss. j rehabil med. 2015; 47: 561–568. doi:10.2340/16501977-1962 13.murray cd, forshaw mj. the experience of amputation and prosthesis use for adults: a metasynthesis. disabil rehabil. 2013; 35: 1133-1142 doi:10.3109/09638288.2012.723790 14.jefferies p, gallagher p, philbin m. being “just normal”: a grounded theory of prosthesis use. disabil rehabil. 2018; 40: 17541763. doi:10.1080/09638288.2017.1312564 15.van eijk ms, van der linde h, buijck b, geurts a, zuidema s, koopmans r. predicting prosthetic use in elderly patients after major lower limb amputation. prosthet orthot int. 2012; 36: 45-52 doi: 10.1177/0309364611430885 16.hershkovitz a, dudkiewicz i, brill s. rehabilitation outcome of post-acute lower limb geriatric amputees. disabil rehabil. 2013; 35: 21-227. doi:10.3109/09638288.2012.690818 https://doi.org/10.33137/cpoj.v4i1.36833 10 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 17.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: 896–900. doi:10.1016/j.apmr.2007.03.016 18.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: 2085–2094. doi:10.3109/09638288.2012.671885 19.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: 144–152. doi:10.1177/ 0309364617695883 20.batten h, lamont r, kuys s, mcphail s, mandrusiak a. what are the barriers and enablers that people with a lower limb amputation experience when walking in the community? disabil rehabil. 2019: 1-7. doi:10.1080/09638288.2019.1597177 21.frieden ra. the geriatric amputee. phys med rehabil clin n am. 2005; 16: 179–195. doi:10.1016/j.pmr.2004.06.004 22.gauthier-gagnon c, grise mc. prosthetic profile of the amputee questionnaire: validity and reliability. arch phys med rehabil. 1994; 75: 1309-1313. doi:10.1016/0003-9993(94)90278-x 23.resnick b, nahm es, orwig d, zimmerman ss, magaziner j. measurement of activity in older adults: reliability and validity of the step activity monitor. j nurs meas. 2001; 9: 275–290. doi:10.1891/1061-3749.9.3.275 24.busse me, van deursen rw, wiles c. real-life step and activity measurement: reliability and validity. j med eng technol. 2009; 33: 33–41. doi:10.1080/03091900701682606 25.floegel ta, florez-pregonero a, hekler eb, buman mp. validation of consumer-based hip and wrist activity monitors in older adults with varied ambulatory abilities. j gerontol a biol sci med sci. 2017; 72: 229–236. doi:10.1093/gerona/glw098 26.coleman kl, smith dg, boone da, joseph aw, del aguila ma. step activity monitor: long-term, continuous recording of ambulatory function. j rehabil res dev. 1999; 36: 8–18. 27.arch es, sions jm, horne j, bodt ba. step count accuracy of stepwatch and fitbit onetm among individuals with a unilateral transtibial amputation. prosthet orthot int. 2018; 42: 518–526. doi:10.1177/0309364618767138 28.grise mc, gauthier-gagnon c, martineau gg a. prosthetic profile of people with lower extremity amputation: conception and design of a follow-up questionnaire. arch phys med rehabil. 1993; 74: 862-870. doi:10.1016/0003-9993(93)90014-2 29.gauthier-gagnon c, gris m-c. tools to measure outcome of people with a lower limb amputation: update on the ppa and lci. j prosthet orthot. 2006; 18: p61–p67. 30.hsieh h-f, shannon se. three approaches to qualitative content analysis. qual health res. 2005;15(9):1277-88. doi:10.1177/1049732305276687 31.international classification of functioning, disability and health (icf) [internet]. geneva: world health organization; 2001, [cited 2021, august 11], available from: https://www.who.int/standards/classifications/internationalclassification-of-functioning-disability-and-health 32.shenton ak. strategies for ensuring trustworthiness in qualitative research projects. educ inform. 2004; 22: 63-75. doi:10.3233/efi-2004-22201 33.mortenson wb, hammell kw, luts a, soles c, miller wc. the power of power wheelchairs: mobility choices of communitydwelling, older adults. scand j occup ther. 2015; 22: 394–401. doi:10.3109/11038128.2015.1049289 34.varpio l, ajjawi r, monrouxe lv, o'brien bc, rees ce. shedding the cobra effect: problematising thematic emergence, triangulation, saturation and member checking. medical education. 2017; 51: 40-50. doi:10.1111/medu.13124 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. 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. 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 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 literature review 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 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 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 r s 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 * t h 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 li z 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 li z 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 ll e c ti o n s e s s io n . b a s e li n 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 ll e 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 research ethics board (reb #16675) at holland bloorview hospital, canada. informed written consent was obtained from each participant before commencing. references 1.kaas jh, merzenich mm, killackey hp. the reorganization of somatosensory cortex following peripheral nerve damage in adult and developing mammals. annu rev neurosci. 1983;6:325–56. doi:10.1146/annurev.ne.06.030183.001545 2. eshraghi a., andrysek j. (2018) influence of prosthetic socket design and fitting on gait. in: müller b., wolf s. (eds) handbook of human motion. springer, cham. pages 1383-1406. doi: 10.1007/ 978-3-319-14418-4_76 3.guertin pa. central pattern generator for locomotion: anatomical, physiological, and pathophysiological considerations. front neurol. 2013;3:1–15. doi:10.3389/fneur.2012.00183 4.sadeghi h, allard p, prince f, labelle h. symmetry and limb dominance in able-bodied gait: a review. gait posture. 2000;12:34– 45. doi:10.1016/s0966-6362(00)00070-9 5.shen x, mak mky. balance and gait training with augmented feedback improves balance confidence in people with parkinson’s disease. neurorehabil neural repair. 2014;28:524–35. doi:10.1177/1545968313517752 6.macintosh a, lam e, vigneron v, vignais n, biddiss e. biofeedback interventions for individuals with cerebral palsy: a systematic review. disabil rehabil. 2019;41:2369–91. doi: 10.1080/09638288.2018.1468933 7.afzal mr, pyo s, oh m-k, park ys, lee b-c, yoon j. haptic based gait rehabilitation system for stroke patients. in 2016 ieee/rsj int conf intell robot syst. 2016;3198–203. doi:10.1109/iros.2016.7759494 8.thrasher ta, flett hm, popovic mr. gait training regimen for incomplete spinal cord injury using functional electrical stimulation. spinal cord. 2006;44:357–61. doi:10.1038/sj.sc.3101864 9.sagawa y, turcot k, armand s, thevenon a, vuillerme n, watelain e. biomechanics and physiological parameters during gait in lower-limb amputees: a systematic review. gait posture. 2011;33:511–26. doi:10.1016/j.gaitpost.2011.02.003 10.nolan l, wit a, dudziñski k, lees a, lake m, wychowañski m. adjustments in gait symmetry with walking speed in trans-femoral and trans-tibial amputees. gait posture. 2003;17:142–51. doi:10.1016/s0966-6362(02)00066-8 11.miller wc, deathe ab, speechley m, koval j. the influence of falling, fear of falling, and balance confidence on prosthetic mobility and social activity among individuals with a lower extremity amputation. arch phys med rehabil. 2001;82:1238–44. doi: 10.1053/apmr.2001.25079 12.seymour r. prosthetics and orthotics: lower limb and spinal. lippincott williams & wilkins; 2002. 13.staiano ae, flynn r. therapeutic uses of active videogames: a systematic review. games health j. 2014;3:351–65. doi:10.1089/ g4h.2013.0100 14.darter bj, wilken jm. gait training with virtual reality–based real-time feedback: improving gait performance following transfemoral amputation. phys ther. 2011;91:1385–94. doi:10.2522/ptj.20100360 15.van gelder lma, barnes a, wheat js, heller bw. the use of biofeedback for gait retraining: a mapping review. clin biomech. 2018;59:159–66. doi:10.1016/j.clinbiomech.2018.09.020 16.escamilla-nunez r, michelini a, andrysek j. biofeedback systems for gait rehabilitation of individuals with lower-limb amputation: a systematic review. sensors. 2020;20:1628. doi:10.3390/s20061628 17.giggins om, persson u, caulfield b. biofeedback in rehabilitation. j neuroeng rehabil. 2013;10:60. doi:10.1186/17430003-10-60 https://doi.org/10.33137/cpoj.v5i1.36744 12 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 18.shull pb, damian dd. haptic wearables as sensory replacement, sensory augmentation and trainer – a review. j neuroeng rehabil. 2015;12:59. doi:10.1186/s12984-015-0055-z 19.lee b-c, fung a, thrasher ta. the effects of coding schemes on vibrotactile biofeedback for dynamic balance training in parkinson’s disease and healthy elderly individuals. ieee trans neural syst rehabil eng. 2018;26:153–60. doi:10.1109/ tnsre.2017.2762239 20.chamorro-moriana g, moreno a, sevillano j. technologybased feedback and its efficacy in improving gait parameters in patients with abnormal gait: a systematic review. sensors. 2018;18:142. doi:10.3390/s18010142 21.shi s, leineweber mj, andrysek j. exploring the tactor configurations of vibrotactile feedback systems for use in lower-limb prostheses. j vib acoust. 2019;141. doi:10.1115/1.4043610 22.sharma a, leineweber mj, andrysek j. effects of cognitive load and prosthetic liner on volitional response times to vibrotactile feedback. j rehabil res dev. 2016;53:473–82. doi:10.1682/ jrrd.2015.04.0060 23.sharma a, torres-moreno r, zabjek k, andrysek j. toward an artificial sensory feedback system for prosthetic mobility rehabilitation: examination of sensorimotor responses. j rehabil res dev. 2014;51:907–17. doi:10.1682/jrrd.2013.07.0164 24.leineweber mj, shi s, andrysek j. a method for evaluating timeliness and accuracy of volitional motor responses to vibrotactile stimuli. j vis exp. 2016;2016. doi:10.3791/54223 25.afzal mr, lee h, eizad a, lee ch, oh m-k, yoon j. evaluation of novel vibrotactile biofeedback coding schemes for gait symmetry training. 2019 2nd ieee int conf soft robot. 2019, 540–5. doi:10.1109/robosoft.2019.8722751 26.lee b-c, thrasher ta, fisher sp, layne cs. the effects of different sensory augmentation on weight-shifting balance exercises in parkinson’s disease and healthy elderly people: a proof-of-concept study. j neuroeng rehabil. 2015;12:75. doi:10.1186/s12984-015-0064-y 27.crea s, edin bb, knaepen k, meeusen r, vitiello n. timediscrete vibrotactile feedback contributes to improved gait symmetry in patients with lower limb amputations: case series. phys ther. 2017;97:198–207. doi:10.2522/ptj.20150441 28.lopez-meyer p, fulk gd, sazonov es. automatic detection of temporal gait parameters in poststroke individuals. ieee trans inf technol biomed. 2011; 15:594–601. doi:10.1109/titb.2011. 2112773 29.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 30.redd cb, bamberg sjm. a wireless sensory feedback device for real-time gait 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 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 existing technologies and open challenges. ieee trans biomed eng. 2018; 65(9): 19962010. doi: 10.1109/tbme.2017.2775100 3.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 4.frossard l, laux s, lee gow d, berg d. role of the prosthetist in provision of bone-anchored prostheses: governmental and practitioner perspectives. the aopa review. 2018; 3(1):26-27. https://eprints.qut.edu.au/123164/ 5.raschke su, orendurff ms, mattie jl, kenyon de, jones oy, moe d, et al. biomechanical characteristics, patient preference and https://doi.org/10.33137/cpoj.v4i2.36364 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 https://eprints.qut.edu.au/123164/ 12 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 activity level with different prosthetic feet: a randomized double blind trial with laboratory and community testing. j biomech. 2015; 48(1): 146-52. doi: 10.1016/j.jbiomech.2014.10.002 6.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 7.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 8.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 lowerlimb prosthesis. j rehabil res dev. 2004; 41(4):555-70. doi: 10.1682/jrrd.2003.06.0102 9.samuelsson ka, töytäri o, salminen al, brandt å. effects of lower limb prosthesis on activity, participation, and quality of life: a systematic review. prosthet orthot int, 2012. 36(2):145-58. doi: 10.1177/0309364611432794 10.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 11.ghillebert j, de bock s, flynn l, geeroms j, tassignon b, roelands b, et al. guidelines and recommendations to investigate the efficacy of a lower-limb prosthetic device: a systematic review. ieee trans. med. robot. bionics. 2019; 1(4):279-296. doi: 10.1109/tmrb.2019.2949855 12.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 13.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 14.campbell jh, stevens pm, wurdeman sr. oasis 1: retrospective analysis of four different microprocessor knee types. rate. 2020;1-10. doi: 10.1177/2055668320968476 15.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 16.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 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 prostheses using osseointegrated fixation. j prosthet orthot. 2021; doi: 10.1097/jpo. 0000000000000372 51.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 52.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):318-327. doi: 10.1177/0309364617740239 53.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 54.o'malley sp. issues facing the australian health technology assessment review of medical technology funding. med j aust. 2010; 193(1): 30-3. doi: 10.5694/j.1326-5377.2010.tb03737.x 55.bertram my, lauer ja, de joncheere k, edejer t, hutubessy r, kieny mp, et al. cost-effectiveness thresholds: pros and cons. bull world health organ. 2016; 94(12): 925-930. doi: 10.2471/blt.15.164418 56.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 57.cape j, beca j, hoch j. introduction to cost-effectiveness analysis for clinicians. univ tor med. 2013; 90(3): 103-105. 58.drummond m, tarricone r, torbica a. incentivizing research into the effectiveness of medical devices. eur j health econ. 2016; 17(9): 1055-1058. doi: 10.1007/s10198-016-0820-3 59. armstrong bk, gillespie ja, leeder sr, rubin gl, russell lm. challenges in health and health care for australia. med j aust. 2007; 187(9): 485-9. 60.gallego g, casey r, norman r, goodall s. introduction and uptake of new medical technologies in the australian health care system: a qualitative study. health policy. 2011; 102(2-3): 152-8. doi: 10.1016/j.healthpol.2011.04.003 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 technol assess health care. 2008; 24(3): 318-25. doi: 10.1017/ s0266462308080422 78.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 79.dobson a, el-gamil a, shimer m, davanzo je. economic value of prosthetic services among medicare beneficiaries: a claimsbased retrospective cohort study, 2011-2014. j neuroeng rehabil. 2018;5;15(suppl 1):55. doi: 10.1186/s12984-018-0406-7 80.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 81.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 82.briggs a, sculpher m, buxton m. 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. 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 li g ib il it y 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 ll o 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 li n ic a ll y 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 li n ic a ll y 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. arch phys med rehabil. 2008;89(3):422-9. doi: 10.1016/j.apmr.2007.11.005 2.dillingham tr, pezzin le, mackenzie ej. limb amputation and limb deficiency: epidemiology and recent trends in the united states. south med j. 2002;95(8):875-83. doi: 10.1097/00007611200208000-00018 3.littman aj, bouldin ed, haselkorn jk. this is your new normal: a qualitative study of barriers and facilitators to physical activity in veterans with lower extremity loss. disabil health j. 2017;10(4):600-6. doi: 10.1016/j.dhjo.2017.03.004 4.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 5.bragaru m, dekker r, geertzen jhb, dijkstra pu. amputees and sports. sports med. 2011;41(9):721-40. doi: 10.2165/11590420000000000-00000 6.deans sa, mcfadyen ak, rowe pj. physical activity and quality of life: a study of a lower-limb amputee population. prosthet orthot int. 2008;32(2):186-200. doi: 10.1080/03093640802016514 7.wetterhahn k, hanson c, levy c. effect of participation in physical activity on body image of amputees. am j phys med rehab. 2002;81:194-201. doi: 10.1097/00002060-20020300000007 8.morgan sj, mcdonald cl, halsne eg, cheever sm, salem r, kramer pa, et al. laboratoryand community-based health outcomes in people with transtibial amputation using crossover and energy-storing prosthetic feet: a randomized crossover trial. plos one. 2018;13(2):e0189652. doi: 10.1371/journal.pone.0189652 9.michie s, ashford s, sniehotta ff, dombrowski su, bishop a, french dp. a refined taxonomy of behaviour change techniques to help people change their physical activity and healthy eating behaviours: the calo-re taxonomy. psychol health. 2011;26(11):1479-98. doi: 10.1080/08870446.2010.540664 10.yamada m, mori s, nishiguchi s, kajiwara y, yoshimura k, sonoda t, et al. pedometer-based behavioral change program can improve dependency in sedentary older adults: a randomized controlled trial. j frailty aging. 2012;1(1):39-44. doi: 10.14283/jfa.2012.7 11.larson er. massage therapy effects in a long-term prosthetic user with fibular hemimelia. j bodyw mov ther. 2015;19(2):261-7. doi: 10.1016/j.jbmt.2014.04.005 12.craig cl, marshall al, sjostrom m, bauman ae, booth ml, ainsworth be, et al. international physical activity questionnaire: 12-country reliability and validity. med sci sports exerc. 2003;35(8):1381-95.doi:10.1249/01.mss.0000078924.61453.fb 13.gallagher p, maclachlan m. the trinity amputation and prosthesis experience scales and quality of life in people with lowerlimb amputation. arch phys med rehabil. 2004;85(5):730-6. doi: 10.1016/j.apmr.2003.07.009 https://doi.org/10.33137/cpoj.v3i1.33931 9 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 14.washburn ra, zhu w, mcauley e, frogley m, figoni sf. the physical activity scale for individuals with physical disabilities: development and evaluation. arch phys med rehabil. 2002;83(2):193-200. doi: 10.1053/apmr.2002.27467 15.salminen a, brandt, samuelsson k, töytäri o, malmivaara a. mobility devices to promote activity and participation: a systematic review. j rehabil med. 2009;41(9):697-706. doi: 10.2340/ 16501977-0427 16.borghouts ja, koes bw, bouter lm. the clinical course and prognostic factors of non-specific neck pain: a systematic review. pain. 1998;77(1):1-13. doi: 10.1016/s0304-3959(98)00058-x 17.shekelle pg, andersson g, bombardier c, cherkin d, deyo r, keller r, et al. a brief introduction to the critical reading of the clinical literature. spine. 1994;19(18 suppl):2028s-31s. doi: 10.1097/00007632-199409151-00002 18.ma jk, martin ginis ka. a meta-analysis of physical activity interventions in people with physical disabilities: content, characteristics, and effects on behaviour. psychol sport exerc. 2018;37:262-73.doi:10.1016/j.psychsport.2018.01.006 19.hendrie ga, brindal e, baird d, gardner c. improving children's dairy food and calcium intake: can intervention work? a systematic review of the literature. public health nutr. 2013;16(02):365-76. doi: 10.1017/s1368980012001322 20.kosma m, cardinal bj, mccubbin ja. a pilot study of a webbased physical activity motivational program for adults with physical disabilities. disabil rehabil. 2005;27(23):1435-42. doi: 10.1080/09638280500242713 21.van der ploeg hp, streppel kr, van der beek aj, van der woude lh, vollenbroek-hutten mm, van harten wh, et al. counselling increases physical activity behaviour nine weeks after rehabilitation. br j sports med. 2006;40(3):223-9. doi: 10.1136/bjsm.2005.021139 22.miller mj, stevens-lapsley j, fields tt, coons d, bray-hall s, sullivan w, et al. physical activity behavior change for older veterans after dysvascular amputation. contemp clin trials. 2017;55:10-5. doi: 10.1016/j.cct.2017.01.008 23.gailey rs, gaunaurd 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. doi: 10.1682/jrrd.2011.04.0077 24.ladlow p, phillip r, etherington j, coppack r, bilzon j, mcguigan mp, et al. functional and mental health status of united kingdom military amputees post rehabilitation. arch phys med rehabil. 2015;96(11):2048-54. doi: 10.1016/j.apmr.2015.07.016 25.van der ploeg hp, streppel kr, van der beek aj, van der woude lh, vollenbroek-hutten mm, van harten wh, et al. successfully improving physical activity behavior after rehabilitation. am j health promot. 2007;21(3):153-9. doi: 10.4278/0890-1171-21.3.153 26.mcdonald cl, kramer pa, morgan sj, halsne eg, cheever sm, hafner bj. energy expenditure in people with transtibial amputation walking with crossover and energy storing prosthetic feet: a randomized within-subject study. gait posture. 2018;62: 349-54. doi: 10.1016/j.gaitpost.2018.03.040 27.klute gk, berge js, orendurff ms, williams rm, czerniecki jm. prosthetic intervention effects on activity of lower-extremity amputees. arch phys med rehabil. 2006;87(5):717-22. doi: 10.1016/j.apmr.2006.02.007 28.delehanty rd, trachsel l. effects of short-term group treatment on rehabilitation outcome of adults with amputations. int j rehabil res. 1995;1(2):61-73. doi: 10.1007/bf02213887 29.christiansen cl, miller mj, murray am, stephenson ro, stevens-lapsley je, hiatt wr, et al. behavior-change intervention targeting physical function, walking, and disability after dysvascular amputation: a randomized controlled pilot trial. arch phys med rehabil. 2018;99(11):2160-7. doi: 10.1016/ j.apmr.2018.04.011 30.littman aj, haselkorn jk, arterburn de, boyko ej. pilot randomized trial of a telephone-delivered physical activity and weight management intervention for individuals with lower extremity amputation. disability and health journal. 2019;12(1):4350 doi: 10.1016/j.dhjo.2018.08.002 31.buis a, dumbleton t, murray k, mchugh b, mckay g, sexton s. measuring the daily stepping activity of people with transtibial amputation using the activpal™ activity monitor. j prosthet orthot. 2014; 26: 43-7. doi: 10.1097/jpo.0000000000000016 32.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. doi: 10.1016/ j.apmr.2004.03.036 33.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):1380-5. 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 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 https://doi.org/10.33137/cpoj.v3i1.33931 10 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 38.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):591602. doi: 10.1682/jrrd.2004.04.0591 39.berge js, czerniecki jm, klute gk. efficacy of shock-absorbing versus rigid pylons for impact reduction in transtibial amputees based on laboratory, field, and outcome metrics. j rehabil res dev. 2005;42(6):795-808. doi: 10.1682/jrrd.2005.02.0034 40.castro o, ng k, novoradovskaya e, bosselut g, hassandra m. a scoping review on interventions to promote physical activity among adults with disabilities. disabil health j. 2018;11(2):174-83. doi: 10.1016/j.dhjo.2017.10.013 41.lai b, young hj, bickel cs, motl rw, rimmer jh. current trends in exercise intervention research, technology, and behavioral change strategies for people with disabilities: a scoping review. am j phys med rehabil. 2017;96(10):748-61. doi: 10.1097/phm.0000000000000743 42.samuelsson ka, töytäri o, salminen a-l, brandt å. effects of lower limb prosthesis on activity, participation, and quality of life: a systematic review. prosthet orthot int. 2012;36(2):145-58. doi: 10.1177/0309364611432794 43.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 44.pasquina pf, perry bn, miller me, ling gsf, tsao jw. recent advances in bioelectric prostheses. neurol clin pract. 2015;5(2):164-70. doi: 10.1212/cpj.0000000000000132 45.ainsworth be, haskell wl, whitt mc, irwin ml, swartz am, strath sj, et al. compendium of physical activities: an update of activity codes and met intensities. med sci sport exer. 2000;32(9 suppl):s498-504. doi: 10.1097/00005768-20000900100009 46.van der ploeg hp, streppel kr, van der beek aj, van der woude lh, vollenbroek-hutten m, van mechelen w. the physical activity scale for individuals with physical disabilities: test-retest reliability and comparison with an accelerometer. j phys activ health. 2007;4(1):96-100. doi: 10.1123/jpah.4.1.96 47.van den berg-emons rj, l'ortye aa, buffart lm, nieuwenhuijsen c, nooijen cf, bergen mp, et al. validation of the physical activity scale for individuals with physical disabilities. arch phys med rehabil. 2011;92(6):923-8. 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 ll o 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 ll e 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 il e 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 il a te ra l d a il y 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 il y 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 ll e 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 il ie 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 il it a 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 il it a 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 il a te ra l (n = 3 2 ) a n d b il a 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 il it a 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 ll e 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 ll e 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 ll in 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 ll s 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 il y 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 il y 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 ll e 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 il it a ti o n a n d s p o rt ) re c e iv e d a c o u n s e ll in g s e s s io n f ro m a s p o rt s c o u n s e ll o 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 il it a 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 ll o 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 il it a 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 il it a ti o n a n d s p o rt + a c ti v e a ft e r r e h a b il it a 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 il it a 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 il it a ti o n a n d s p o rt + a c ti v e a ft e r r e h a b il it a 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 il it a 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 il it a ti o n ' in 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 il it a 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 il it y 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 il a 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 ll e 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 ll a 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 il a te ra l (n = 4 8 ) c a d e n c e , d a il y 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 il y 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 il a 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 il a 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 li n 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 ll e d r e v e rs a l (a -b -a -b ) tr ia l c o n tr o ll e 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 li m 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 il a te ra l (n = 1 7 ) d a il y s te p c o u n t a n d e s ti m a te d d a il y 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 il y s te p a c ti v it y o r d a il y 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 li m a ti o n fo ll o 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 il a te ra l (n = 1 5 ) d a il y e n e rg y e x p e n d it u re d o u b ly l a b e ll e 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 il y 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 il a te ra l t ra n s ti b ia l (n = 1 5 ) d a il y 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 il a te ra l t ra n s fe m o ra l (n = 5 ) d a il y 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 il a 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 il a te ra l (n = 2 7 ) d a il y 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 il y 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 il a te ra l (n = 1 0 ) d a il y 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 il y 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 ll y l o w e r in t h e t o rs io n a d a p te r. s e ll e 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 il e t h e c o n tr o l g ro u p r e c e iv e d a p a te ll a 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 li m 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 ll e 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 il a 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 li ty 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 li n e a n d f o ll o 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 il a 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 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 ll in 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 learning vision-based manipulation. inasme international mechanical engineering congress and exposition 2021 nov 1 (vol. 85604, p. v006t06a017). american society of mechanical engineers. doi:10.48550/arxiv.2103.02099 2.resnik l, meucci mr, lieberman-klinger s, fantini c, kelty dl, disla r, et al. advanced upper limb prosthetic devices: implications for upper limb prosthetic rehabilitation. arch phys med rehabil. 2012;93(4):710-7. doi: 10.1016/j.apmr.2011.11.010 3.head j. the effect of socket movement and electrode contact on myoelectric prosthesis control during daily living activities (phd thesis). university of salford (united kingdom); 2014. http://usir.salford.ac.uk/id/eprint/30774/ 4.vujaklija i, farina d, aszmann oc. new developments in prosthetic arm systems. orthop res rev. 2016;8:31. doi: 10.2147/ orr.s71468 5.olsen j, day s, dupan s, nazarpour k, dyson m. 3d-printing and upper-limb prosthetic sockets: promises and pitfalls. ieee trans neural syst rehabilitation eng. 2021;29:527-35. doi: 10.1109/tnsre.2021.3057984 6.lake c. the evolution of upper limb prosthetic socket design. j prosthet orthot. 2008;20(3):85-92. doi: 10.1097/jpo. 0b013e31817d2f08 7.miguelez jm, lake c, conyers d, zenie j. the transradial anatomically contoured (trac) interface: design principles and methodology. j prosthet orthot. 2003;15(4):148-57. doi: 10.1097/ 00008526-200310000-00007 8.the promise of assistive technology to enhance activity and work participation. washington (dc): national academies press (us); 2017; available from: https://www.ncbi.nlm.nih.gov/books/nbk453289/. doi:10.17226/ 24740 9.clement rg, bugler ke, oliver cw. bionic prosthetic hands: a review of present technology and future aspirations. surgeon. 2011 ;9(6):336-40. doi: 10.1016/j.surge.2011.06.001 10.salminger s, stino h, pichler lh, gstoettner c, sturma a, mayer ja, et al. current rates of prosthetic usage in upper-limb amputees–have innovations had an impact on device acceptance?. disabil rehabil. 2020;21:1-2. doi: 10.1080/09638288.2020. 1866684 11.hermens h, stramigioli s, rietman h, veltink p, misra s. myoelectric forearm prostheses: state of the art from a usercentered perspective. j rehabil res dev. 2011;48(6):719. doi: 10.1682/jrrd.2010.08.0161 https://doi.org/10.33137/cpoj.v5i2.37963 http://usir.salford.ac.uk/id/eprint/30774/ https://www.ncbi.nlm.nih.gov/books/nbk453289/ 10 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 12.biddiss ea, chau tt. upper limb prosthesis use and abandonment: a survey of the last 25 years. prosthet orthot int. 2007;31(3):236-57. doi: 10.1080/03093640600994581 13.mcfarland lv, hubbard winkler sl, heinemann aw, jones m, esquenazi a. unilateral upper-limb loss: satisfaction and prosthetic-device use in veterans and servicemembers from vietnam and oif/oef conflicts. j rehabil res dev. 2010; 47(4):299-316. 14.smail lc, neal c, wilkins c, packham tl. comfort and function remain key factors in upper limb prosthetic abandonment: findings of a scoping review. disabil rehabil assist technol. 2021;16(8):821-30. doi: 10.1080/17483107.2020.1738567 15.head js, howard d, hutchins sw, kenney l, heath gh, aksenov ay. the use of an adjustable electrode housing unit to compare electrode alignment and contact variation with myoelectric prosthesis functionality: a pilot study. prosthet orthot int. 2016;40(1):123-8. doi: 10.1177/0309364614545417 16.chadwell a, kenney l, thies s, galpin a, head j. the reality of myoelectric prostheses: understanding what makes these devices difficult for some users to control. front neurorobot. 2016;10:7. doi: 10.3389/fnbot.2016.00007 17.fang y, hettiarachchi n, zhou d, liu h. multi-modal sensing techniques for interfacing hand prostheses: a review. ieee sens j. 2015;15(11):6065-76. doi: 10.1109/jsen.2015.2450211 18.belter jt, dollar am. performance characteristics of anthropomorphic prosthetic hands. in 2011 ieee international conference on rehabilitation robotics. 2011; 1-7. doi: 10.1109/ icorr.2011.5975476 19.trejo-letechipia ma, rodriguez-sanchez da, gonzálezgonzález rb, perez-sanpablo ai, arizmendi-morquecho am, lara-ceniceros te, et al. design and manufacturing of a bodypowered hook with force regulation system and composite-based nanomaterials. appl. 2021;11(9):4225. doi: 10.3390/app11094225 20.alley rd, williams tw, albuquerque mj, altobelli de. prosthetic sockets stabilized by alternating areas of tissue compression and release. j rehabil res dev. 2011;48(6):679-96. doi: 10.1682/jrrd.2009.12.0197 21.sang y, li x, luo y. biomechanical design considerations for transradial prosthetic interface: a review. proc inst mech eng h p i mech eng h. 2016;230(3):239-50. doi: 10.1177/ 0954411915624452 22.alley rd. advancement of upper extremity prosthetic interface and frame design. mec '02 the next generation, proceedings of the 2002 myoelectric controls/powered prosthetics symposium fredericton, new brunswick, canada: august 21–23, 2002. 23.morrison h. gran who lost limbs from septic paper cut can't wait to eat burger with bionic hand [internet]. glasgow times. 2021; [cited 2 august 2021]. available from: https://www.glasgowtimes.co.uk/news/18994494.glasgowhospital-patient-becomes-first-benefit-bionic-hand/ 24.sperlich b, born dp, swarén m, kilian y, geesmann b, kohlbareis m, et al. is leg compression beneficial for alpine skiers?. bmc sports sci. med. rehabilitation. 2013;5(1):1-2. doi: 10.1186/ 2052-1847-5-18 25.balcombe l, miller c, mcguiness w. approaches to the application and removal of compression therapy: a literature review. br j community nurs. 2017;22(sup10):s6-14. doi: 10.12968/bjcn.2017.22(sup10)s6-14 26.snyder cj. the influence of a directional compression garment on muscle activity and performance in recreational alpine skiers (phd thesis). montana state university-bozeman, college of education, health & human development), 2018. https://scholarworks.montana.edu/xmlui/handle/1/14591 27.hsu wc, tseng lw, chen fc, wang lc, yang ww, lin yj, et al. effects of compression garments on surface emg and physiological responses during and after distance running. j sport health sci. 2020;9(6):685-91. doi: 10.1016/j.jshs.2017.01.001 28.wang x, xia r, fu w. reduced muscle activity during isokinetic contractions associated with external leg compression. technol health care. 2016;24(s2):s533-9. doi: 10.3233/thc-161179 29.moffatt c. wound essentials 3: problem solving preventing pressure damage. wound essentials. 2010; 3:48-58. https://www.woundsinternational.com/resources/details/woundessentials-3-problem-solving-preventing-pressure-damage 30.karadağ-saygı e, giray e. the clinical aspects and effectiveness of suit therapies for cerebral palsy: a systematic review. turk j phys med rehabil. 2019;65(1):93. doi: 10.5606/ tftrd.2019.3431 31.gefen a. the biomechanics of sitting‐acquired pressure ulcers in patients with spinal cord injury or lesions. int. wound j. 2007;4(3):222-31. doi: 10.1111/j.1742-481x.2007.00330.x 32.chang wl, seigreg aa. prediction of ulcer formation on the skin. med. hypotheses. 1999;53(2):141-4. doi: 10.1054/mehy. 1998.0733 33.lim cs, davies ah. graduated compression stockings. cmaj. 2014;186(10):e391-8. doi: 10.1503/cmaj.131281 34.vaena ml, sinnecker jp, pinto bb, neves mf, serraguimarães f, marques rg. effects of local pressure on cutaneous blood flow in pigs. rev col bras cir. 2017;44:498-504. doi: 10.1590/0100-69912017005012 35.bluestein d, javaheri a. pressure ulcers: prevention, evaluation, and management. am fam physician. 2008;78(10):1186-94. 36.lyons kr. axopy: a python library for implementing humancomputer interface experiments. j open source softw. 2019;4(34):1191. doi: 10.21105/joss.01191 37.alley rd, williams iii tw, inventors. methods for bone stabilization. united states patent us 10,702,404. 2020 july 7. 38.dupan ss, krasoulis a, nazarpour k. intramuscular emg for abstract myoelectric control: a proof of concept study. in 2020 42nd annual international conference of the ieee engineering in medicine & biology society (embc) 2020; 3277-3280. ieee. doi: 10.1109/embc44109.2020.9175402 39.klass m, levenez m, enoka rm, duchateau j. spinal mechanisms contribute to differences in the time to failure of submaximal fatiguing contractions performed with different loads. j neurophysiol. 2008;99(3):1096-104. doi: 10.1152/jn.01252.2007 40.gillani nv, ghista dn. muscle fatigue induced by sustained isometric contraction. hum. factors. 1973;15(1):67-73. doi: 10.1177/001872087301500108 https://doi.org/10.33137/cpoj.v5i2.37963 https://www.glasgowtimes.co.uk/news/18994494.glasgow-hospital-patient-becomes-first-benefit-bionic-hand/ 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 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 6.armstrong tw, williamson mlc, elliott tr, jackson wt, kearns nt, ryan t. psychological distress among persons with upper extremity limb loss. br j health psychol. 2019;24(4):746-63. doi: 10.1111/bjhp.12360 7.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:10.1037/0090-5550.48.2.109 8.desmond dm, maclachlan m. affective distress and amputationrelated pain among older men with long-term, traumatic limb amputations. j pain symptom manage. 2006;31(4):362-8. doi: 10.1016/j.jpainsymman.2005.08.014 9.desteli ee, imren y, erdogan m, sarisoy g, cosgun 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 10.saradjian a, thompson ar, datta d. the experience of men using an upper limb prosthesis following amputation: positive coping and minimizing feeling different. disabil rehabil. 2008;30(11):871-83. doi: 10.1080/09638280701427386 11.kristjansdottir f, dahlin lb, rosberg he, carlsson ik. social participation in persons with upper limb amputation receiving an esthetic prosthesis. j hand ther. 2019. doi: 10.1016/j.jht.2019.03.010 12.desmond dm, maclachlan m. coping strategies as predictors of psychosocial adaptation in a sample of elderly veterans with acquired lower limb amputations. soc sci med. 2006;62(1):208-16. doi: 10.1016/j.socscimed.2005.05.011 13.talbot sg, carty mj, jensen se, dumanian ga. adjustment to amputation and interest in upper limb transplantation. sage open medicine. 2019; 7:2050312119858248. doi: 10.1177/ 2050312119858248 14.murray cd. the social meanings of prosthesis use. j health psychol. 2005;10(3):425-41. doi:10.1177/1359105305051431 15.murray c, ed. amputation, prosthesis use, and phantom limb pain. university l, editor. lancaster la1 4yt, uk: springer science & business media. 2009 16.atherton r, robertson n. psychological adjustment to lower limb amputation amongst prosthesis users. disabil rehabil. 2006;28(19):1201-9. doi: 10.1080/09638280600551674 17.coffey l, gallagher p, horgan o, desmond d, maclachlan m. psychosocial adjustment to diabetes-related lower limb amputation. diabet med. 2009;26(10):1063-7. doi: 10.1111/j. 1464-5491.2009.02802.x 18.resnik l, ekerholm s, borgia m, clark ma. a national study of veterans with major upper limb amputation: survey methods, participants, and summary findings. plos one. 2019;14(3):e0213578. doi: 10.1371/journal.pone.0213578 https://doi.org/10.33137/cpoj.v5i1.37873 11 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 19.biddiss ea, chau tt. upper limb prosthesis use and abandonment: a survey of the last 25 years. prosthet orthot int. 2007;31(3):236-57. doi: 10.1080/03093640600994581 20.gallagher p, maclachlan m. the trinity amputation and prosthesis experience scales and quality of life in people with lower-limb amputation. arch phys med rehabil. 2004;85(5):730-6. doi: 10.1016/j.apmr.2003.07.009 21.gallagher p, maclachlan m. development and psychometric evaluation of the trinity amputation and prosthesis experience scales (tapes). rehabil psychol. 2000;45(2):130-54. doi:10.1037/0090-5550.45.2.130 22.desmond dm, maclachlan m. factor structure of the trinity amputation and prosthesis experience scales (tapes) with individuals with acquired upper limb amputations. am j phys med rehabil. 2005;84(7):506-13. doi: 10.1097/01.phm.0000166885. 16180.63 23.peterson ch, peterson na, powell kg. cognitive interviewing for item development: validity evidence based on content and response processes. meas eval couns dev. 2017;50(4):217-23. doi: 10.1080/07481756.2017.1339564 24.levine re, fowler fj, jr., brown ja. role of cognitive testing in the development of the cahps hospital survey. health serv res. 2005;40(6 pt 2):2037-56. doi: 10.1111/j.1475-6773.2005.00472.x 25.irwin de, varni jw, yeatts k, dewalt da. cognitive interviewing methodology in the development of a pediatric item bank: a patient reported outcomes measurement information system (promis) study. health qual life outcomes. 2009;7:3. doi: 10.1186/14777525-7-3 26.revelle w. procedures for psychological, psychometric, and personality research [internet]. evanston, illinois: northwestern university; 2021 [cited 2021 december 17]. available from: https://cran.r-project.org/package=psych 27.muthen l, muthen b. mplus statistical analysis with latent variables user's guide. los angeles, ca: muthen & muthen; 2007. 28.yen w. scaling performance assessments: strategies for managing local item dependence. j educ meas. 1993;30(3):187213. doi: 10.1111/j.1745-3984.1993.tb00423.x 29.tate r. a comparison of selected empirical methods for assessing the structure of responses to test items. appl psychol meas. 2003;27(3):159-203. doi: 10.1177/0146621603027003001 30.chen w, thissen d. local dependence indexes for item pairs using item response theory. j educ behav stat. 1997;22:265-89. doi: 10.3102/10769986022003265 31.tennant a, conaghan pg. the rasch measurement model in rheumatology: what is it and why use it? when should it be applied, and what should one look for in a rasch paper? arthritis rheum. 2007;57(8):1358-62. doi: 10.1002/art.23108 32.tennant a, mckenna sp, hagell p. application of rasch analysis in the development and application of quality of life instruments. value health. 2004;7 suppl 1:s22-6. doi: 10.1111/j.1524-4733.2004.7s106.x 33.zwick r, thayer, d.t., lewis, c. an empirical bayes approach to mantel-haenszel dif analysis. j educ meas. 1999;36(1):1-28. 34.koo tk, li my. a guideline of selecting and reporting 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 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 investigate the efficacy of a lower-limb prosthetic device: a systematic review. ieee trans. med. robot. bionics. 2019; 1(4):279-296. doi: 10.1109/tmrb.2019.2949855 2.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 3.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 4.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 5.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/ 6.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 7.kannenberg a, seidinger s. health economics: the perspective of a prosthetic manufacturer. j prosthet orthot. 2019; 31(1s). doi:10.1097/jpo.0000000000000234 8.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 9.frossard l, laux s, lee gow d, berg d. role of the prosthetist in 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 evaluations of prosthetic care innovations. can prosthet orthot j. 2021; v4,i2. doi:10.33137/cpoj.v4i2.36364 14.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 15.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 16.cape j, beca j, hoch j. introduction to cost-effectiveness analysis for clinicians. univ tor med. 2013; 90(3): 103-105 17.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 18.frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. can prosthet orthot j. 2021; v4,i2. doi: 10.33137/cpoj.v4i2.36365 19.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):318-327. doi: 10.1177/0309364617740239 20.frossard l, ferrada l, quincey t, berg d. cost-effectiveness of transtibial bone-anchored prostheses using osseointegrated fixation. j prosthet orthot. 2021; doi: 10.1097/jpo. 0000000000000372 21.murakami t, murray k. outcomes of knee disarticulation and the influence of surgical techniques in dysvascular patients: a systematic review. prosthet orthot int, 2016. 40(4): 423-35. doi: 10.1177/0309364615574163 https://doi.org/10.33137/cpoj.v4i2.36366 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/ 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 13 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 22.guirao l, samitier b, maldonado d, rodríguez-piñero m, exposito j. evaluation of functional health and well-being in 23 transfemoral amputees after distal weight-bearing implant j orthop res. 2018; 192(04): 1-11. doi: 10.29011/2575-8241. 000092 23.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 24.guirao l, samitier b, maldonado d, rodriguez-piñero m, expósito j, peraita-costa i, et al. improvement in bone mineral density after a distal weight-bearing implant in a series of 13 cases. j prosthet orthot. 2020; 32(2): 116-120. doi:10.1097/ jpo.0000000000000299 25.guirao l, samitier cb, costea m, camos jm, majo m, pleguezuelos e. improvement in walking abilities in transfemoral amputees with a distal weight bearing implant. prosthet orthot int, 2017; 41(1): 26-32. doi: 10.1177/0309364616633920 26.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 27.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 28.boone da. the economic value of mobility with a prosthesis. j prosthet orthot. 2019; 31(1s). doi: 10.1097/jpo. 0000000000000231 29.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 30.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. 31.frossard l. innovations of health services and economic evaluation of bone-anchored prosthesis using osseointegration: the queensland artificial limb service’s experience 2019 scientific report, ed. l. frossard. 2020, brisbane, australia: yourresearchproject. 19. 32.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 33.frossard l, leech b, pitkin m. inter-participant variability data in loading applied on osseointegrated implant by transtibial boneanchored prostheses during daily activities. data in brief, 2019. 26: 104510. doi: 10.1016/j.dib.2019.104510 34.frossard l, leech b, pitkin m. inter-participant variability data in characterization of anthropomorphicity of prosthetic feet fitted to bone-anchored transtibial prosthesis. data in brief, 2019. 25:104195. doi: 10.1016/j.dib.2019.104195 35.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 36.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 37.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 38.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 39.gallego g, casey r, norman r, goodall s. introduction and uptake of new medical technologies in the australian health care system: a qualitative study. health policy. 2011; 102(2-3): 152-8. doi: 10.1016/j.healthpol.2011.04.003 40.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 41.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 42.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 43.prochor p. finite element analysis of stresses generated in cortical bone during implantation of a novel limb prosthesis osseointegrated fixation system. biocybern biomed eng. 2017; 37(2): 255-262. doi: 10.1016/j.bbe.2016.12.001 44.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; 69-81. doi: 10.37190//abb01543-2020-02 45.van eck cf, mcgough rl. clinical outcome of osseointegrated prostheses for lower extremity amputations: a systematic review of the literature. curr orthop pract. 2015; 26(4): 349-357. doi: 10.1097/bco.0000000000000248 46.atallah r, leijendekkers ra, hoogeboom tj, frölke jp. complications of bone-anchored prostheses for individuals with an extremity amputation: a systematic review. plos one. 2018; 13(8):e0201821. doi: 10.1371/journal.pone.0201821 47.hansson e, hagberg k, cawson m, brodtkorb th. patients with unilateral transfemoral amputation treated with a percutaneous osseointegrated prosthesis: a cost-effectiveness analysis. bone https://doi.org/10.33137/cpoj.v4i2.36366 14 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 joint j. 2018; 100-b(4):527-534. doi: 10.1302/0301-620x. 100b4.bjj-2017-0968.r1 48.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 49.basu a, maciejewski ml. choosing a time horizon in cost and cost-effectiveness analyses. jama. 2019; 321(11):1096. doi: 10.1001/jama.2019.1153 50.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 51.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 52.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 53.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 54.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 55.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 56.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 57.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 58.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 59.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 60.hagberg k, ghassemi jahani sa, kulbacka-ortiz k, thomsen p, malchau h, reinholdt c. a 15-year follow-up of transfemoral amputees with bone-anchored transcutaneous prostheses. bone joint j. 2020; 102-b(1): 55-63. doi: 10.1302/0301620x.102b1.bjj-2019-0611.r1 61.geil, mark. jpo editor's comments. j prosthet orthot, 2016; 28, 93-94. doi:10.1097/jpo. 0000000000000100 62.beaudette r, fiedler g. appropriateness of sample sizes in published research on prosthetic knee componentry. j prosthet orthot. 2018; 30(2). 63.opra implant system instructions for use [internet]. 2016; [cited 2021, june 9]. available from: https://www.accessdata.fda.gov/cdrh_docs/pdf8/h080004d.pdf 64.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 65.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 66.frossard l, 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 67.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: 10.1097/00008526200601001-00017 68.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 69.richmond j. economic science in lower-limb prosthetic rehabilitation: the consumer’s perspective.j prosthet 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 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 borgia 15 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 test 28 bbt functional test of manual dexterity swedish disabilities of the arm shoulder and hand questionnaire 29 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 procedure 30 shap functional test of hand function using abstract objects and adl orthotics and prosthetics user's survey 31 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 test 32 9hpt functional measure of finger dexterity 36-item short form survey 33 sf-36 qol self-reported measure of quality of life temporal measures tm functional time-based activities and tasks edinburgh handedness inventory 34 ehi functional assessment of hand dominance modified action research arm test 35 marat functional assessment of hand function during grasp, pinch, grip and gross movements visual analogue scale 36 vas qol measure of severity of symptoms trinity amputation and prosthetic experience scale 37 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 components 38 vr-12 functional & qol self-reported measure of health jebsen-taylor hand function tests 39 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 amputation 40 am-ula functional measure of upper limb activity performance michigan hand outcomes questionnaire 41 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 tests 42 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 index 43 mki functional measure of hand mobility carroll upper extremity function test 44 ueft functional measure of functional impairment and severity purdue pegboard test 45 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 assessment 46 400-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 system 47 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 prosthetics and orthotics. ethical approval ethical approval was not needed. references 1.biryukova ev, yourovskaya vz. a model of human hand dynamics. in: schuind f, an kn, cooney wp, garcia-elias m. (eds) advances in the biomechanics of the hand and wrist. nato asi series, 1994; vol 256. springer, boston, ma. doi: 10.1007/978-1-4757-9107-5_11 2.jones l, lederman s. human hand function. new york: oxford, 2006. 3.edemekong pf, bomgaars dl, sukumaran s, schoo c. activities of daily living. in: statpearls [internet]. treasure island (fl): statpearls publishing; 2022 jan– pmid: 29261878. 4.amputation explained [internet]. blesma, [cited: 2022 july 22]. available from: https://blesma.org/media/327345/2-amputationexplained.pdf 5.evidence appraisal report: multi-grip myoelectric upper limb prosthetics for upper limb amputees [internet]. health technology wales. [cited: 2022 july 22]. available from: https://www.healthtechnology.wales/wpcontent/uploads/2019/12/ear014-multigrip-upper-limbprosthetics.pdf 6.chadwell a, kenney l, thies s, galpin a, head j. the reality of myoelectric prostheses: understanding what makes these devices difficult for some users to control. front neurorobot. 2016; 10: 1-21. doi: 10.3389/fnbot.2016.00007 7.biddiss e, chau t. upper limb prosthesis use and abandonment: a survey of the last 25 years. prosthet orthot int. 2007; 31: 236257. doi: 10.1080/03093640600994581 8.pantaleon l. why measuring outcomes is important in health care. j vet intern med. 2019; 33: 356-362. doi: 10.1111/jvim. 15458 9.mackenzie h, dewey a, drahota a, kilburn s, kalra p, fogg c, et al. systematic reviews: what they are, why they are important, and how to get involved. journal of clinical and preventive cardiology. 2012; 1: 193-202. 10.systematic reviews and meta-analyses: a step-by-step guide [internet]. edinburgh tuo. [cited: 2022 july 22]. available from: https://www.ccace.ed.ac.uk/research/softwareresources/systematic-reviews-and-metaanalyses/step7?phpmyadmin=ulk8xfsbayfqjav7hgjo-sdykp3 11.prisma 2009 flow diagram [internet]. prisma. [cited: 2022 july 22]. available from: http://www.prisma-statement.org 12.casp checklists [internet]. casp. [cited: 2022 july 22]. available from: https://casp-uk.net/casp-tools-checklists/ 13.sobuh m, kenney lp, galpin aj, thies sb, mclaughlin j, kulkarni j, et al. visuomotor behaviours when using a myoelectric prosthesis. j neuroeng rehabil. 2014; 11: 72. 2014/04/25. doi: 10.1186/1743-0003-11-72 14.lawrence el, dayanidhi s, fassola i, requejo p, leclercq c, winstein cj, et al. outcome measures for hand function naturally reveal three latent domains in older adults: strength, coordinated upper extremity function, and sensorimotor processing. front aging neurosci. 2015;7:108. doi:10.3389/fnagi. 2015.00108 15.resnik l, borgia m. responsiveness of outcome measures for upper limb prosthetic rehabilitation. prosthet orthot int. 2016; 40: 96-108. 2014/10/23. doi: 10.1177/0309364614554032 16.raveh e, portnoy s, friedman j. myoelectric prosthesis users improve performance time and accuracy using vibrotactile feedback when visual feedback is disturbed. arch phys med rehabil. 2018;1;99(11):2263-70. doi: 10.1016/j.apmr.2018.05.019 17.lee s, lee h, lee j, ryu h, kim iy, kim j. clip-on imu system for assessing age-related changes in hand functions. sensors. 2020; 20: 6313. doi:10.3390/s20216313 18.eklund e, svensson e, häger-ross c. hand function and disability of the arm, shoulder and hand in charcot-marie-tooth disease. disabil rehabil. 2009; 31: 1955-1962. doi:10.1080/ 09638280902874170 19.hruby la, gstoettner c, sturma a, salminger s, mayer ja, aszmann oc. bionic upper limb reconstruction: a valuable alternative in global brachial plexus avulsion injuries-a case series. j clin med. 2019; 9. doi:10.3390/jcm9010023 20.resnik lj, borgia ml, clark ma. a national survey of prosthesis use in veterans with major upper limb amputation: comparisons by gender. pm&r. 2020; 12: 1086-1098. doi: 10.1002/pmrj.12351 21.resnik l, borgia m, clark m. function and quality of life of unilateral major upper limb amputees: effect of prosthesis use and type. arch phys med rehabil. 2020; 101: 1396-1406. doi: 10.1016/j.apmr.2020.04.003 22.speth ka, yoon ap, wang l, chung kc. assessment of treebased statistical learning to estimate optimal personalized treatment decision rules for traumatic finger amputations. jama netw. 2020; 3: e1921626. 2020/02/23. doi: 10.1001/ jamanetworkopen.2019.21626. 23.wang sl, bloomer c, civillico g, kontson k. application of machine learning to the identification of joint degrees of freedom involved in abnormal movement during upper limb prosthesis use. plos one. 2021; 16: e0246795. 2021/02/12. doi: 10.1371/journal. pone.0246795 24.hruby la, sturma a, mayer ja, pittermann a, salminger s, aszmann oc. algorithm for bionic hand reconstruction in patients with global brachial plexopathies. j neurosurg. 2017; 127: 11631171. doi: 10.3171/2016.6.jns16154 25.de boer e, romkema s, cutti ag, brouwers ma, bongers rm, van der sluis ck. intermanual transfer effects in below-elbow myoelectric prosthesis users. arch phys med rehabil. 2016; 97: 1924-1930. doi: 10.1016/j.apmr.2016.04.021 26.bouma se, postema sg, bongers rm, dijkstra pu, van der sluis ck. musculoskeletal complaints in individuals with finger or partial hand amputations in the netherlands: a cross-sectional study. disabil rehabil. 2018; 40: 1146-1153. doi: 10.1080/ 09638288.2017.1289418 27.bernardon l, gazarian a, petruzzo p, packham t, guillot m, guigal v, et al. bilateral hand transplantation: functional benefits assessment in five patients with a mean follow-up of 7.6 years https://doi.org/10.33137/cpoj.v5i2.39023 https://blesma.org/media/327345/2-amputation-explained.pdf https://blesma.org/media/327345/2-amputation-explained.pdf https://www.healthtechnology.wales/wp-content/uploads/2019/12/ear014-multigrip-upper-limb-prosthetics.pdf https://www.healthtechnology.wales/wp-content/uploads/2019/12/ear014-multigrip-upper-limb-prosthetics.pdf https://www.healthtechnology.wales/wp-content/uploads/2019/12/ear014-multigrip-upper-limb-prosthetics.pdf https://www.ccace.ed.ac.uk/research/software-resources/systematic-reviews-and-meta-analyses/step7?phpmyadmin=ulk8xfsbayfqjav7hgjo-sdykp3 https://www.ccace.ed.ac.uk/research/software-resources/systematic-reviews-and-meta-analyses/step7?phpmyadmin=ulk8xfsbayfqjav7hgjo-sdykp3 https://www.ccace.ed.ac.uk/research/software-resources/systematic-reviews-and-meta-analyses/step7?phpmyadmin=ulk8xfsbayfqjav7hgjo-sdykp3 http://www.prisma-statement.org/ https://casp-uk.net/casp-tools-checklists/ 11 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 (range 4–13 years). j plast reconstr aesthet surg. 2015; 68: 11711183. doi: 10.1016/j.bjps.2015.07.007 28.mathiowetz v, volland g, kashman n, weber k. adult norms for the box and block test of manual dexterity. am j occup ther. 1985;39(6):386-91. doi:10.5014/ajot.39.6.386 29.gummesson c, atroshi i, ekdahl c. the disabilities of the arm, shoulder and hand (dash) outcome questionnaire: longitudinal construct validity and measuring self-rated health change after surgery. bmc musculoskelet disord. 2003;4:11. doi: 10.1186/1471-2474-4-11 30.southampton hand assessment procedure [internet]. university of southampton. [cited: 2022 july 22]. available from: http://www.shap.ecs.soton.ac.uk/ 31.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(3), 191–206. doi:10.1080/03093640308726682 32.mathiowetz v, weber k, kashman n, volland g. adult norms for the nine hole peg test of finger dexterity. otjr. 1985;5(1):24-38. doi:10.1177/153944928500500102 33.36-item short form survey (sf-36) [internet]. rand health care. [cited: 2022 july 22]. available from: https://www.rand.org/health-care/surveys_tools/mos/36-itemshort-form.html 34.robinson j. edinburgh handedness inventory. in: volkmar fr. (eds) encyclopedia of autism spectrum disorders. springer, new york, ny. 2013. doi:10.1007/978-1-4419-1698-3_877 35.wilson n, howel d, bosomworth h, shaw l, rodgers h. analysing the action research arm test (arat): a cautionary tale from the ratuls trial. int j rehabil res. 2021;166-169, doi:10.1097/mrr.0000000000000466 36.klimek l, bergmann kc, biedermann t, bousquet j, hellings p, jung k, et al. visual analogue scales (vas): measuring instruments for the documentation of symptoms and therapy monitoring in cases of allergic rhinitis in everyday health care. allergo j int. 2017;26(1):16-24. doi: 10.1007/s40629-016-0006-7 37.gallagher p, maclachlan m. development and psychometric evaluation of the trinity amputation and prosthesis experience scales (tapes). rehabil psychol. 2000; 45(2), 130–154. doi:10.1037/0090-5550.45.2.130 38.vr-12 [internet]. code technology. [cited: 2022 july 22]. available from: https://www.codetechnology.com/blog/vr-12general-health-pro-tool/ 39.tipton-burton m. jebsen–taylor hand function test. in: kreutzer js, deluca j, caplan b. (eds) encyclopedia of clinical neuropsychology. springer, new york, ny. 2011. doi:10.1007/978-0-387-79948-3_1946 40.resnik l, adams l, borgia m, delikat j, disla r, ebner c, et al. development and evaluation of the activities measure for upper limb amputees. arch phys med rehabil. 2013; 94(3), 488–494.e4. doi:10.1016/j.apmr.2012.10.004 41.chung kc, pillsbury ms, walters mr, hayward ra. reliability and validity testing of the michigan hand outcomes questionnaire. j hand surg am. 1998; 23(4), 575–587. doi:1016/s03635023(98)80042-7 42.unb test of prosthetics function [internet]. university of new brunswick. [cited: 2022 july 22]. available from: https://www.unb.ca/ibme/_assets/documents/test-of-prostheticfunction.pdf 43.lefevre-colau mm, poiraudeau s, oberlin c, demaille s, fermanian j, rannou f, et al. reliability, validity, and responsiveness of the modified kapandji index for assessment of functional mobility of the rheumatoid hand. arch phys med rehabil. 2003; 84(7), 1032–1038. doi:10.1016/s0003-9993(03)00128-x 44.upper extremity function test (ueft) [internet]. stroke engine. [cited: 2022 july 22]. available from: https://strokengine.ca/en/assessments/upper-extremity-functiontest-ueft/ 45.tiffin j, asher ej. the purdue pegboard: norms and studies of reliability and validity. j appl psychol. 1948; 32(3), 234–247. doi:10.1037/h0061266 46.konzelmann m, burrus c, gable c, luthi f, paysant j. prospective multicentre validation study of a new standardised version of the 400-point hand assessment. bmc musculoskelet disord. 2020; 21, 313. doi:10.1186/s12891-020-03303-4 47. lanzetta m, petruzzo p. a comprehensive functional score system in hand transplantation. in: lanzetta m, dubernard jm, petruzzo p. (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. 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 li c 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 li c 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 rehabilitation following amputation: the pioneering swedish model. unfallchirurg. 2017; 1-8. doi: 10.1007/s00113-017-0331-4 4.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 5.kunutsor sk, gillatt d, blom aw. systematic review of the safety and efficacy of osseointegration prosthesis after limb amputation. br j surg. 2018; 105(13):1731-1741. doi: 10.1002/bjs.11005 6.frossard l, gow dl, hagberg k, cairns n, contoyannis b, gray s, et al. apparatus for monitoring load bearing rehabilitation exercises of a transfemoral amputee fitted with an osseointegrated fixation: a proof-of-concept study. gait posture. 2010; 31(2): 2238. doi: 10.1016/j.gaitpost.2009.10.010. 7.hagberg, k. branemark r. one hundred patients treated with osseointegrated transfemoral amputation prostheses-rehabilitation perspective. j rehabil res dev. 2009: 46(3): 331-44. doi: 10.1682/jrrd.2008.06.0080 8.hagberg k, ghassemi jahani sa, kulbacka-ortiz k, thomsen p, malchau h, reinholdt c. a 15-year follow-up of transfemoral amputees with bone-anchored transcutaneous prostheses. bone joint j. 2020; 102-b(1): 55-63. doi: 10.1302/0301620x.102b1.bjj-2019-0611.r1 9.aschoff hh, mcgough r. the endo-exo femoral prosthesis: a new rehabilitation concept following above knee amputation. jj bone joint surg. 2012; 94-b(supp xxxix): 77. 10.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 11.direct skeletal fixation of limb or digit prostheses using intraosseous transcutaneous implants-information for the public [internet]. the national institute for health and clinical excellence (nice). 2008; [cited 2021,june 9]. available from: https://www.nice.org.uk/guidance/ipg270 12.gallego g, casey r, norman r, goodall s. introduction and uptake of new medical technologies in the australian health care system: a qualitative study. health policy. 2011; 102(2-3): 152-8. doi: 10.1016/j.healthpol.2011.04.003 13.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 14.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 15.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):318-327. doi: 10.1177/0309364617740239 16.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 17.frossard l, laux s, lee gow d, berg d. role of the prosthetist in provision of bone-anchored prostheses: governmental and practitioner perspectives. the aopa review. 2018; 3(1): 26-27. https://eprints.qut.edu.au/123164/ 18.frossard l, ferrada l, quincey t, berg d. cost-effectiveness of transtibial bone-anchored prostheses using osseointegrated fixation. j prosthet orthot. 2021; doi: 10.1097/jpo. 0000000000000372 19.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 20.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 21.frossard l. data supporting the 2017 queensland artificial limb service’s science report about innovations of health services and economic evaluation of transfemoral bone-anchored prostheses. 2020; mendeley data. doi: 10.17632/jvcs88b9mz.1 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.frossard l, debra b, merlo g, quincey t, burkett b. governmental perspective on fair and equitable provision of boneanchored prostheses: barriers and facilitators, in xvith international society of prosthetics and orthotics (ispo) world congress. 2017; cape town, south africa. p. 487. 24.burkett b, frossard l, berg d, formosa d. the cost and time effectiveness of osseointegration compared to the traditional socket prosthesis, in university of the sunshine coast university research week. 2014; sunshine coast, australia. p. 27. https://doi.org/10.33137/cpoj.v4i2.36210 https://www.nice.org.uk/guidance/ipg270 18 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 25.frossard l, danielle f, tanya q, debra b, brendan b. cost effectiveness of osseointegration, in 2nd australasian osseointegrated for amputees conference. 2015; brisbane, australia. p. 3. 26.frossard l, gregor m, tanya q, debra b, brendan b. costeffectiveness of bone-anchored prosthesis: the queensland experience, in australian orthotic prosthetic association (aopa) congress. 2015; adelaide, australia. p. 13. 27.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. 28.frossard l, gregory m, tanya q, brendan b, debra b. the queensland health’s experience in provision of bone-anchored prostheses: the hidden treasure of health services and economic evaluations, in university of the sunshine coast research showcase. 2017; sunshine coast, australia. p. 3. 29.frossard l, berg d. governmental perspectives on the quality improvement for provision of bone-anchored prostheses, in australian orthotic prosthetic association (aopa) congress. 2018; gold coast, australia. p. 4. 30.frossard l, berg d. provision of bone-anchored prostheses using osseointegrated implant: leading role of queensland artificial limb service, in herston state of the art healthcare symposium. 2019; brisbane, australia. p. 32. 31.frossard l, berg d, cost-effectiveness of provision of transtibial bone-anchored prosthesis: the queensland experience, in australian orthotic prosthetic association (aopa) congress. 2019; melbourne, australia. p. 23. 32.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. 33.frossard l. innovations of health services and economic evaluation of bone-anchored prosthesis using osseointegration: the queensland artificial limb service’s experience 2019 scientific report, ed. l. frossard. 2020, brisbane, australia: yourresearchproject. 19. 34.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 35.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/ 36.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 37.frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: basic framework. can prosthet orthot j. 2021; v4,i2. doi:10.33137/cpoj.v4i2.36365 38.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 39.guirao l, samitier b, frossard l. a preliminary cost-utility analysis of the prosthetic care innovations: case of the keep walking implant. can prosthet orthot j. 2021; v4,i2. doi: 10.33137/cpoj.v4i2.36366 40.clarke l, dillon m, shiell a. health economic evaluation in orthotics and prosthetics: a systematic review protocol. syst rev. 2019; 8(1): 152. doi: 10.1186/s13643-019-1066-9 41.hermodsson y, persson bm. cost of prostheses in patients with unilateral transtibial amputation for vascular disease: a populationbased follow-up during 8 years of 112 patients. acta orthop scand. 1998; 69(6): 603-607. doi: 10.3109/17453679808999264 42.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: 10.1097/00008526200601001-00017 43.virgo ks. the bionic human health promotion for people with implanted prosthetic devices. humana press; 2006. chapter 3costs of follow-up after implantation of prosthetic devices. p. 33-45. doi: 10.1007/978-1-59259-975-2 44.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 45.clark v. anthropomorphic feet may reduce risk to oi implants [internet]. the o&p edge. 2021; [cited 2021, june 9]. available from: https://opedge.com/articles/viewarticle/2021-0217/anthropomorphic-feet-may-reduce-risk-to-oi-implants 46.pitkin m, frossard l. loading effect of prosthetic feet’s anthropomorphicity on transtibial osseointegrated implant. mil med. 2021; 186(supplement 1): 681-687. doi: 10.1093/milmed/ usaa461 47.frossard l, llyod d. the future of bionic limbs. research features. 2021; 134(134): 54-57. doi: 10.26904/rf-134-7477 48.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; 69-81. doi: 10.37190//abb01543-2020-02 49.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 50.lee wc, doocey jm, brånemark r, adam cj, evans jh, pearcy mj, et al. fe stress analysis of the interface between the bone and an osseointegrated implant for amputees--implications to refine the rehabilitation program. clin biomech. 2008; 23(10):124350. doi: 10.1016/j.clinbiomech.2008.06.012 51.ash s, o’connor j, anderson s, ridgewell e, clarke l. a mixedmethods research approach to the review of competency standards for orthotist/prosthetists in australia. int j evid based healthc. 2015; 13(2): 93-103. doi: 10.1097/xeb.0000000000000038 https://doi.org/10.33137/cpoj.v4i2.36210 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 https://opedge.com/articles/viewarticle/2021-02-17/anthropomorphic-feet-may-reduce-risk-to-oi-implants https://opedge.com/articles/viewarticle/2021-02-17/anthropomorphic-feet-may-reduce-risk-to-oi-implants 19 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 52.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 53.bertram my, lauer ja, de joncheere k, edejer t, hutubessy r, kieny mp, et al. cost-effectiveness thresholds: pros and cons. bull world health organ. 2016; 94(12): 925-930. doi: 10.2471/blt.15.164418 54.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 55.cape j, beca j, hoch j. introduction to cost-effectiveness analysis for clinicians. univ tor med. 2013; 90(3): 103-105. 56.frossard l, stevenson n, smeathers j, häggström e, hagberg k, sullivan j, et al. monitoring of the load regime applied on the osseointegrated fixation of a trans-femoral amputee: a tool for evidence-based practice. prosthet orthot int. 2008; 32(1): 68-78. doi: 10.1080/03093640701676319 57.hagberg k, brånemark r, gunterberg b, rydevik b. osseointegrated trans-femoral amputation prostheses: prospective results of general and condition-specific quality of life in 18 patients at 2-year follow-up. prosthet orthot int. 2008; 32(1): 29-41. doi: 10.1080/03093640701553922 58.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 59.tillander j, hagberg k, hagberg l, brånemark r. osseointegrated titanium implants for limb prostheses attachments: infectious complications. clin orthop relat res. 2010; 468(10):2781-8. doi: 10.1007/s11999-010-1370-0 60.nebergall a, bragdon c, antonellis a, kärrholm j, brånemark r, malchau h. stable fixation of an osseointegated implant system for above-the-knee amputees: titel rsa and radiographic evaluation of migration and bone remodeling in 55 cases. acta orthop. 2012; 83(2): 121-8. doi: 10.3109/17453674.2012.678799 61.rubin l, kennon l, keggi j, aschoff h. surgical management of trans-femoral amputation with a transcutaneous, press-fit distal femoral intra-medullary device: analysis with minimum 2 year follow-up. j bone joint surg. 2012;1:95. 62.frossard l, haggstrom e, hagberg k, branemark r. load applied on bone-anchored transfemoral prosthesis: characterization of a prosthesis-a pilot study. j rehabil res dev. 2013; 50(5): 619-34. doi: 10.1682/jrrd.2012.04.0062 63.frossard l. evaluation framework to assess benefits and harms of bone-anchored prosthesis, in 6th international conference advances in orthopaedic osseointegration. 2015: las vegas, nevada, usa. p. 20. 64.brånemark r, berlin ö, hagberg k, bergh p, gunterberg b, rydevik b. a novel osseointegrated percutaneous prosthetic system for the treatment of patients with transfemoral amputation: a prospective study of 51 patients. bone joint j. 2014; 96(1): 106113. doi: 10.1302/0301-620x.96b1.31905 65.uglow m, fitzpatrick kf. the osseointegration group of australia accelerated protocol (ogaap-1) for two-stage osseointegrated reconstruction of amputated limbs editorial. bone joint j. 2016; 98-b(7). 66.al muderis m, lu w, tetsworth k, bosley b, li jj. single-stage osseointegrated reconstruction and rehabilitation of lower limb amputees: the osseointegration group of australia accelerated protocol-2 (ogaap-2) for a prospective cohort study. bmj open. 2017; 7(3). doi: 10.1136/bmjopen-2016-013508 67.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 68.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 69.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 70.frossard l, 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 71.basu a, maciejewski ml. choosing a time horizon in cost and cost-effectiveness analyses. jama. 2019; 321(11):1096. doi: 10.1001/jama.2019.1153 72.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 73.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 74.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 75.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 76.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 77.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 78.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 79.ijzerman mj, steuten lm. early assessment of medical technologies to inform product development and market access: a https://doi.org/10.33137/cpoj.v4i2.36210 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 20 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 review of methods and applications. appl health econ health policy. 2011; 9(5): 331-47. doi: 10.2165/11593380-00000000000000 80.kannenberg a, seidinger s. health economics: the perspective of a prosthetic manufacturer. j prosthet orthot. 2019; 31(1s). doi:10.1097/jpo.0000000000000234 81.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 82.vertriest s, pather s, sondergeld p, ramis ma, frossard l. rehabilitation programs after the implantation of transfemoral osseointegrated fixations for bone-anchored prostheses: a systematic review protocol. jbi database system rev implement rep. 2017; 15(3): 607-619. doi: 10.11124/jbisrir-2016-003023 83.li y, lindeque b. percutaneous osseointegrated prostheses for transfemoral amputations. orthopedics. 2018; 41(2): 75-80. doi: 10.3928/01477447-20180227-03 84.van de meent h, hopman mt, frolke jp. walking ability and quality of life in subjects with transfemoral amputation: a comparison of osseointegration with socket prostheses. arch phys med rehabil. 2013; 94(11): 2174-2178. doi: 10.1016/ j.apmr.2013.05.020 85.atallah r, leijendekkers ra, hoogeboom tj, frölke jp. complications of bone-anchored prostheses for individuals with an extremity amputation: a systematic review. plos one. 2018; 13(8):e0201821. doi: 10.1371/journal.pone.0201821 86.frolke jp, leijendekkers ra, van de meent h. osseointegrated prosthesis for patients with an amputation: multidisciplinary team approach in the netherlands. unfallchirurg. 2017; 120(4):293-299. doi: 10.1007/s00113-016-0302-1 87.leijendekkers ra, van hinte g, frölke jp, van de meent h, nijhuis-van der sanden mw, et al. comparison of bone-anchored prostheses and socket prostheses for patients with a lower extremity amputation: a systematic review. disabil rehabil. 2017; 39(11):1045-1058. doi: 10.1080/09638288.2016.1186752 88.van eck cf, mcgough rl. clinical outcome of osseointegrated prostheses for lower extremity amputations: a systematic review of the literature. curr orthop pract. 2015; 26(4): 349-357. doi: 10.1097/bco.0000000000000248 89. hebert js, rehani m, stiegelmar r. osseointegration for lower;limb amputation: a systematic review of clinical outcomes. jbjs rev, 2017. 5(10): e10. doi: 10.2106/jbjs.rvw.17.00037 90.tepe v, peterson cm, editors. full stride: advancing the state of the art in lower extremity gait systems. springer; 2017. doi: 10.1007/978-1-4939-7247-0 91.al muderis mm, lu wy, li jj, kaufman k, orendurff m, highsmith mj, et al. clinically relevant outcome measures following limb osseointegration; systematic review of the literature. j orthop trauma. 2018; 32(2): doi: 10.1097/ bot.0000000000001031 92.maryniak a, laschowski b, andrysek j. technical overview of osseointegrated transfemoral prostheses: orthopedic surgery and implant design centered. jesmdt. 2018; 1(2). doi: 10.1115/1.4039105 93.thesleff a, branemark r, hakansson b, ortiz-catalan m. biomechanical characterisation of bone-anchored implant systems for amputation limb prostheses: a systematic review. ann biomed eng. 2018; 46(3): 377-391. doi: 10.1007/s10439-017-1976-4 94.overmann al, aparicio c, richards jt, mutreja i, fischer ng, wade sm, et al. orthopaedic osseointegration: implantology and future directions. j orthop res. 2019; doi: 10.1002/jor.24576 95.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 96.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 97.hoyt bw, walsh sa, forsberg ja. osseointegrated prostheses for the rehabilitation of amputees (opra): results and clinical perspective. expert rev med devices. 2020; 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