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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 
 

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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 hands-

on 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, Cost-

Utility, 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


 

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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 

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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 non-

prosthetic 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 

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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 

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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 K-

levels, 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.  

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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 

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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% pre-

implantation 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 

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ISSN: 2561-987X 
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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.  

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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 microprocessor-

controlled 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-to-

pay  

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
t-

c
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-to-

pay 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 

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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 

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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 K-

Level (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 

 

 

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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 

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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 K-

Level (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 K-

Level 
Cost Utility 

K-
Level 

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 

 

 

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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 

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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 life-

year (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]

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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 

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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 case-

base 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  

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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 

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These comparisons suggested that the KWI has the 

potential to be more cost effective than current socket-

suspended 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 

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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. 

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Orthotics Journal. 2021; Volume 4, Issue 2, No.11.  https://doi.org/10.33137/cpoj.v4i2.36366 

ISSN: 2561-987X 
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Orthotics Journal. 2021; Volume 4, Issue 2, No.11.  https://doi.org/10.33137/cpoj.v4i2.36366 

ISSN: 2561-987X 
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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. 

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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 

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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

