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VOLUME 8, ISSUE 2 

 2025 
 

RESEARCH ARTICLE 

 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 

controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823 

 

 

  

 

https://jps.library.utoronto.ca/index.php/cpoj/index
mailto:cpoj@online-publication.com
https://publicationethics.org/about/our-organisation
https://pmc.ncbi.nlm.nih.gov/journals/?term=%22Canadian+Prosthetics+%26+Orthotics+Journal%22
https://members.publicationethics.org/members/canadian-prosthetics-orthotics-journal
https://doi.org/10.33137/cpoj.v8i2.45823
https://pmc.ncbi.nlm.nih.gov/journals/?term=%22Canadian+Prosthetics+%26+Orthotics+Journal%22


 

1 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

 

 

RESEARCH ARTICLE 

 

HEALTH ECONOMIC EVALUATION OF MICROPROCESSOR AND NON-MICROPROCESSOR 

CONTROLLED PROSTHETIC KNEES 

Bosman C.E.1*, van der Sluis C.K.1, Vrieling A.H.1, Geertzen J.H.B.1, Seves B.L.1, Groen H.2 

1. Department of Rehabilitation Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. 
2. Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. 
  
 

 

 

 

  

 

 

 

 

 

 

 

 

 

INTRODUCTION   

A lower limb amputation (LLA) can negatively impact daily 

activities, participation, and other aspects of life.1-3 

Individuals with a transfemoral amputation or knee-

disarticulation can use a prosthesis with a knee unit. 

Prostheses for persons with a transfemoral amputation or 

knee disarticulation feature knee units, which are typically 

classified as non-microprocessor controlled (mechanical) 

knees (NMPK) or microprocessor controlled knees (MPK). 

NMPKs may be purely mechanical or can include 

pneumatic or hydraulic systems to assist in swing and/or 

stance phase control. MPKs, equipped with sensors and a  

 

microprocessor, can automatically adjust to the user's 

movements during swing and stance phases. The higher 

acquisition cost of the MPK is due to not only the inclusion 

of more advanced and expensive electronic components, 

but also research and development expenses, as well as 

testing and regulatory compliance requirements. 

Nevertheless, research suggests that the MPK may offer 

added value for both active individuals, due to their adaptive 

capabilities,4 and older users, for whom safety and stability 

are particularly beneficial.5 Despite these potential benefits 

of the MPK, such as reduced stumbles and falls,6-10 and 

improvements in walking speed, satisfaction, confidence 

and quality of life (QoL),6,8,9,11-13 it is unclear whether these 

benefits justify the additional expense.   

In the Netherlands, approximately 10,000 people use a 

lower limb prosthesis (LLP),14 with an estimated one-third 

having a transfemoral amputation or knee disarticulation.15 

Over the past decade, annual healthcare costs for LLPs 

have increased by over 30%, from €30.4 million in 2012 to 

 

* CORRESPONDING AUTHOR: 
Charlotte E. Bosman,  

Affiliation: Department of Rehabilitation Medicine, University of Groningen, 
University Medical Center Groningen, Groningen, The Netherlands. 

E-Mail: c.e.bosman@umcg.nl 

ORCID ID: https://orcid.org/0000-0001-7950-5893 
 

 

 
OPEN  ACCESS 

ABSTRACT 

BACKGROUND: Use of a microprocessor-controlled knee (MPK) compared to a non-microprocessor-

controlled knee (NMPK) can lead to improved walking ability, confidence and satisfaction. However, the MPK 

is more expensive than the NMPK and it is unknown whether the higher costs outweigh the potential benefits. 

OBJECTIVE:  To evaluate the cost-utility and cost-effectiveness of MPKs and NMPKs from a societal 

perspective in the Netherlands. 

METHODOLOGY: Participants completed the Dutch version of the EuroQol - five dimensions - five levels (EQ-

5D-5L) to assess health-related quality of life, three subscales (ambulation, utility and well-being) of the 

Prosthesis Evaluation Questionnaire (PEQ) to assess prosthesis-related quality of life and a cost-questionnaire 

from societal perspective. Incremental cost-utility ratio (ICUR) and incremental cost-effectiveness ratio (ICER) 

were calculated and the ICUR was compared with the Dutch willingness-to-pay threshold. Bootstrapping was 

used to estimate statistical uncertainty, and multiple imputation was applied to account for missing values.  

FINDINGS: In total, 111 participants were included (37 female, 73 male, 1 unknown; 71 transfemoral, 39 knee 

disarticulation, 1 unknown; age 64 ± 13 years; 49 NMPK users, 62 MPK users). The cost-utility analysis 

demonstrated that the MPK yielded an increase of 0.032 quality adjusted life years (QALY) but at considerably 

higher costs. The mean cost difference was € 14,626, resulting in a mean ICUR of € 457,063 per QALY gained. 

The cost difference was mainly driven by acquisition costs but was partially compensated by lower costs of 

work absence, health care consumption and household care. 

CONCLUSION: The cost-effectiveness analyses demonstrated that the MPK is likely to provide benefits in term 

of prosthesis-specific quality of life, but at higher costs. However, short-term (6 months) improvement in health-

related quality of life was too small to result in substantial QALY gain to offset the higher costs of the MPK and 

result in an incremental cost-utility ratio below the generally accepted willingness-to-pay thresholds. 

 

 

ARTICLE INFO 

Received: August 7, 2025 

Accepted: October 14, 2025 

Published: October 30, 2025 
 

CITATION 

Bosman C.E, van der Sluis C.K, 

Vrieling A.H, Geertzen J.H.B, 

Seves B.L, Groen H. Health 

economic evaluation of 

microprocessor and non-

microprocessor controlled 

prosthetic knees. Canadian 

Prosthetics & Orthotics Journal. 

2025; Volume 8, Issue 2, No. 3. 

https://doi.org/10.33137/cpoj.v8

i2.45823 

KEYWORDS 

Lower Limb; Amputation; 

Prostheses; Cost Analysis; 

Quality of Life; Questionnaire; 

Mobility; Microprocessor Knee; 

Cost-effectiveness; Knee 

Disarticulation; Transfemoral. 

Journal Homepage: https://jps.library.utoronto.ca/index.php/cpoj/index 

Volume 8, Issue 2, Article No. 3. 2025 

 

 

https://doi.org/10.33137/cpoj.v8i2.45823
https://orcid.org/0000-0001-7950-5893
https://doi.org/10.33137/cpoj.v8i2.45823
https://doi.org/10.33137/cpoj.v8i2.45823
https://jps.library.utoronto.ca/index.php/cpoj/index


 

2 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

€42.5 million in 2019*, with per-user costs rising from 

€3,110 to €4,400.14 The relationship between these cost 

increases and MPK prescriptions has not been studied. 

Besides the prosthesis acquisition cost, other factors such 

as visits to healthcare professionals, prosthesis repairs and 

home environment adjustments must be considered. 

Additionally, MPK use can affect a person’s productivity and 

ability to contribute to society. To fully understand the cost-

utility and cost-effectiveness of prosthetic knees, a societal 

perspective that includes all these factors is essential.  

Economic evaluations can be used to inform policy 

decisions about the allocation of health care funds 

irrespective of the disease.16 The most commonly used 

types of economic evaluations are the cost-utility analysis 

and cost-effectiveness analysis.17 For both the cost-utility 

analysis and cost-effectiveness analysis, the difference in 

costs (incremental costs) is divided by the difference in 

effects (incremental effects), resulting in either an 

incremental cost utility ratio (ICUR) or an incremental cost 

effectiveness ratio (ICER).17  

In a cost-utility analysis, the effects are expressed in quality-

adjusted life years (QALYs), and this analysis can therefore 

be used for broad comparisons. The value of the ICUR can 

be compared across different diseases and to the threshold 

value for willingness-to-pay for one QALY. The cost-

effectiveness analysis on the other hand, can use 

prosthesis-related effect measures for a more specific 

comparison.   

Several studies have performed a cost-utility analysis to 

compare the  MPK to the NMPK, and reported ICURs within 

the willingness-to-pay threshold.18-22 However, ICURs 

varied widely,18,20 likely due to differences in study design 

and perspectives. Variations in healthcare costs and 

insurance coverage across countries also contribute to this 

disparity, raising questions about the generalizability in the 

Netherlands. A Dutch study by Seelen et al.23 compared 

MPKs to NMPKs in a cost-consequence design and 

reported that the average annual costs per person was 

lower for MPK users compared to NMPK users, but without 

calculating incremental cost and effect differences. Higher 

MPK acquisition costs were offset by lower costs in other 

areas, such as housekeeping assistance and productivity 

loss.23 

Given that previous economic evaluation studies were 

conducted outside the Netherlands and their results cannot 

be translated to the Dutch healthcare system, we performed 

an economic evaluation of MPKs and NMPKs in the 

Netherlands. The objectives of this study were to calculate 

the incremental cost-utility ratio and incremental cost-

effectiveness ratio from a societal perspective and assess 

the relation of the incremental cost-utility ratio to the Dutch 

willingness-to-pay threshold.24 Based on previous 

studies,18-21,25 we hypothesized that the MPK would be cost-

effective compared to the NMPK. 

METHODOLOGY 

The Dutch guideline for the conduct of economic 

evaluations in healthcare was applied.17 Results are 

presented in accordance with the Consolidated Health 

Economic Evaluation Reporting Standards (CHEERS) 

statement.26  

The Medical Ethics Committee of the University Medical 

Center Groningen (METc 2019/419) provided a waiver for 

formal approval. Research was conducted according to the 

Declaration of Helsinki and its amendments.  

All participants were asked to provide their written informed 

consent before completing the survey. This study was 

registered at Clinicaltrials.gov: NCT06105944.   

Data Collection and Analyses 

• Participants 

Individuals with a unilateral transfemoral amputation or 

knee-disarticulation, who were using a prosthesis, were 

eligible for participation. The inclusion criteria were: (1) at 

least 18 years old; (2) at least one year post amputation; (3) 

able to read and write in Dutch; (4) using a prosthesis with 

socket. Participants were recruited via two large prosthetic 

companies with multiple branches in the Netherlands.  

• Data Collection 

Postal surveys were sent to eligible participants between 

December 2022 and March 2023. Non-respondents 

received a reminder after 12 weeks. Participants received a 

€10 gift voucher for their participation. 

Study data were collected and managed using REDCap 

electronic data capture tools.27,28 Participants who did not 

meet the inclusion criteria, did not state their prosthetic knee 

type or did not complete the EQ-5D-5L were excluded from 

analyses.  

Survey Development 

The survey consisted of a questionnaire with four separate 

sections: 1) patient demographics; 2) costs related to LLP 

use; 3) health-related QoL, and 4) prosthesis-related QoL.  

• Patient Demographics 

Participants provided information on their age, sex, 

educational level, employment status, the side and level of 

their limb loss, the type of prosthetic knee they were 

currently using, and their years of prosthesis experience. 

*More recent cost data were not available due to inconsistencies in the registration of assistive devices by health insurance companies. As a result, the National Health 

Care Institute has restricted access to detailed datasets (email correspondence, November 2024). 

https://doi.org/10.33137/cpoj.v8i2.45823


 

3 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

• Costs Related to Prosthesis Use 

To assess medical consumption and productivity costs, we 

combined the iMTA Medical Consumption Questionnaire 

(iMCQ)29 and the iMTA Productivity Cost Questionnaire 

(iPCQ).30 The iMCQ measures medical consumption, 

household assistance, and help from friends and family, 

while the iPCQ evaluates productivity losses, including 

absenteeism, presenteeism, and unpaid work.31 To tailor 

the questionnaires to LLP users, we replaced questions 

about dieticians, speech therapists and emergency room 

visits with questions about prosthesis type and visits to a 

rehabilitation facility or certified prosthetist/orthotist (CPO). 

Furthermore, we added questions about personal costs for 

prosthesis acquisition, repairs, home or vehicle adjustments 

and hobbies. This resulted in a 24-items questionnaire 

(Appendix I). Psychometric properties of this questionnaire 

are not available. 

While no validity studies have been conducted yet, the 

majority of the questions within the iPCQ were sourced from 

existing validated questionnaires, with the exception of the 

section addressing “productivity losses related to unpaid 

work”31 Moreover, the development of the iMCQ took place 

in the Netherlands, tailoring it to the country’s healthcare 

system.29  

The recall periods of the iMCQ and iPCQ were extended to 

six months to capture a reliable overview of LLP-related 

costs. The recall period defines the time span participants 

should reflect on when answering the questionnaire items. 

Direct medical costs, informal care, and travel expenses 

were derived from the questionnaires, while indirect medical 

costs related to productivity loss were calculated using the 

friction cost method with a friction period of 115 days, 

including the value of unpaid work.17 The friction cost 

method estimates the economic impact of productivity 

losses due to illness or premature death by considering only 

the time required to replace a worker and restore 

production, rather than the entire period of absence. Costs 

for appointments with healthcare providers were valued at 

standard Dutch prices,32 and costs for an appointment with 

the CPO were based on average outpatient consultation 

costs.32 Acquisition costs for NMPK and MPK were based 

on information derived from orthopaedic workshops, and 

presenteeism and absenteeism were determined according 

to Dutch guidelines.32 

• Health-Related Quality of Life 

Participants completed the Dutch version of the EuroQol - 

five dimensions - five levels (EQ-5D-5L),33,34 a self-

assessment tool with five questions on mobility, self-care, 

daily activities, pain, and anxiety/depression. Each question 

has five response levels, defining a unique health state. The 

Dutch scoring algorithm for the EQ-5D-5L was used to 

compute a single value representing health status. Scores 

can range from -0.466 to 1, with a higher score representing 

a better QoL.35 Participants also rated their perceived health 

on a visual analogue scale (VAS) from 0 (worst imaginable 

health) to 100 (best imaginable health). The EQ-5D-5L is a 

reliable and valid questionnaire,36 with satisfactory 

measurement properties for patients with major unilateral 

LLA.37 

• Prosthesis-Related Quality of Life 

The utility, ambulation and well-being scales of the 

Prosthesis Evaluation Questionnaire (PEQ) were used, as 

they align with EQ-5D-5L items. The PEQ is a reliable and 

valid self-report tool for evaluating prosthesis-related QoL.38 

It includes nine scales, as well as several separate 

questions which can be used independently.39 Questions 

are scored on a VAS (0-100), with higher scores indicating 

more positive outcomes.  

Health Economic Evaluation 

Two methods are commonly used for an economic 

evaluation: 1) a cost-utility analysis or 2) a cost-

effectiveness analysis. In a cost-utility analysis, the effects 

are expressed in quality-adjusted life years (QALYs). 

QALYs are calculated by adjusting life years for a utility 

measure reflecting quality, ranging from 0 (death) to 1 (full 

health).16 In this study, the utility score of the EQ-5D-5L was 

multiplied with the six-month measurement period to 

calculate the QALYs. Comparing the difference in QALYs to 

the difference in costs, results in the incremental cost-utility 

ratio (ICUR), or cost per QALY gained40 (see equations 

below). The value of this parameter can be compared 

across different diseases and also to the threshold value for 

willingness-to-pay for a gain of one QALY. The values of 

these willingness-to-pay thresholds vary across countries 

and are linked to the burden of disease (higher burden of 

disease equals a higher threshold). In contrast, a cost-

effectiveness analysis uses a clinical effect measure to 

calculate the incremental cost-effectiveness ratio (ICER), 

representing the additional cost per unit of a specific health 

outcome, such as improved mobility or prosthesis-related 

QoL (see equation below). Unlike the cost-utility analysis, 

which uses QALYs as a generic measure, a cost-

effectiveness analysis can focus on specific, relevant 

outcomes for prosthesis users. This allows for a more 

detailed understanding of how cost differences between 

prosthetic knees can impact prosthesis users' daily lives. 

𝐼𝐶𝑈𝑅 =
∆𝐶𝑜𝑠𝑡

∆𝑄𝐴𝐿𝑌
 (1)   

𝐼𝐶𝐸𝑅 =
∆𝐶𝑜𝑠𝑡

∆𝐸𝑓𝑓𝑒𝑐𝑡
 (2) 

ICUR: incremental cost utility ratio; ICER: incremental cost 

effectiveness ratio; ∆: difference. 

The economic evaluation in this study was based on cross-

sectional data, adopting a societal perspective and 

including direct medical costs and indirect costs. The ICUR 

https://doi.org/10.33137/cpoj.v8i2.45823


 

4 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

was calculated by dividing the mean cost difference 

between NMPK and MPK by the mean QALY difference 

based on the EQ-5D-5L. Furthermore, three ICERs were 

calculated by dividing the mean cost difference by the mean 

score difference on the PEQ scales. 

To estimate statistical uncertainty and robustness of results, 

we used the bootstrap method to simulate 5000 repetitions 

of the study, with variations in mean incremental costs and 

effects.41 Bootstrap results are presented as a scatterplot in 

a cost-effectiveness plane (CE-plane) with incremental 

effects on the x-axis and incremental costs on the y-axis. 

The CE-plane is divided into the north-east (NE) quadrant, 

the north-west (NW) quadrant, the south-west (SW) 

quadrant and the south-east (SE) quadrant. Replications in 

these quadrants represent the following results: NE (better 

health outcomes, higher cost), NW (worse health outcomes, 

higher cost), SE (better health outcomes, lower cost), and 

SW (worse health outcomes, lower cost). The bootstrap 

results were used to construct a cost-effectiveness 

acceptability curve (CEAC) summarizing the probability of 

cost-effectiveness of the MPK over the NMPK at various 

willingness-to-pay thresholds for each QALY gained. The 

value of this threshold depends on the burden of disease 

(Appendix II - Table 1A). A specific burden of disease score 

was not available for LLA or prosthesis use and was 

therefore calculated based on the Dutch guidelines24 

(Appendix II -Table 2A). 

Statistical Analyses 

To address missing data, we applied multiple imputation 

and bootstrapping. Multiple imputation was used to 

generate several complete datasets by replacing missing 

values with plausible estimates based on observed data 

patterns. Bootstrapping was then performed on these 

imputed datasets to assess the stability and variability of the 

results, providing more reliable statistical inference while 

accounting for uncertainty introduced by the missing values. 

Missing values for CPO visits and informal care (11 and 3 

cases, respectively) were imputed using average numbers. 

Prior to bootstrap replication, missing data for healthcare 

visits (10 cases) were handled by multiple imputation, 

adjusted for age, sex, prosthesis type, amputation level, and 

prosthesis side. The average of 50 imputations was used 

for the bootstrap procedure. 

Continuous variables were assessed for normality and 

variance equality using Q-Q plots, Kolmogorov-Smirnov 

 

 

f 

Survey sent to LLP users (N=642)

Responses entered into RedCap
(N = 166)

Included in HEE (N = 111)

Did not meet inclusion criteria (N = 55)

- No KD or TFA (N = 8)

- Bilateral limb loss (N = 12)

- Did not use LLP (N = 5)

- Osseointegration (N = 16)

- LLP type unknown (N = 2)

- Did not complete all surveys (N = 12)

Declined (N = 7)

- Declined participation (N = 3)

- Ineligible (N = 4)

Not possible to contact (N = 19)

- No up-to-date address information (N = 9)

- Deceased (N = 6)

- Return to sender/unknown (N = 4)

No Response (N = 450)

Figure 1: Flowchart of survey distribution (blue), response (yellow), and inclusion process (green) for the health economic evaluation (HEE). 

LLP: lower limb prosthesis; KD: knee-disarticulation; TFA: transfemoral amputation. 

https://doi.org/10.33137/cpoj.v8i2.45823


 

5 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

tests, and Levene’s tests. Differences in demographics,  

EQ-5D-5L utility and VAS scores, PEQ scale scores, and 

costs between groups of prosthesis users were evaluated 

using Kruskal-Wallis tests, Mann-Whitney U tests or 

unpaired t-tests for continuous variables, and a Pearson’s 

χ2 test for categorical variables. All tests were two-tailed 

with significance set at p<0.05. Since none of the 

continuous variables met the assumptions of a one-way 

ANOVA, only Kruskal-Wallis tests were performed, followed 

by Mann-Whitney U tests with Bonferroni correction 

(p<0.005). Data analyses were conducted using IBM SPSS 

Statistics version 28 (IBM Corporation, Armonk, NY, USA) 

and Stata version 18 SE (StataCorp, College Station, TX, 

USA).  

RESULTS 

Surveys were sent to 642 participants, with 166 responding 

(response rate 28.5%) (Figure 1). Forty-one respondents did 

not meet the inclusion criteria. Additionally, the knee type 

was unknown for two respondents and twelve respondents 

did not complete all parts of the survey. Ultimately, 111 

respondents were included (age 64 ± 13 years; Table 1). 

MPK users were significantly younger and the time since 

amputation was significantly lower compared to NMPK 

users. Furthermore, we found significant differences in 

whether participants were using their first prosthesis and if 

they had obtained a new prosthesis within the last six 

months, with the NMPK group scoring higher in both 

scenarios. 

Costs Related to Prosthesis 

All cost components, including visits to healthcare 

professionals, prosthesis acquisition, and productivity 

losses, were valued using Dutch standard pricing and data 

obtained from orthopaedic workshops and national 

guidelines (Table 2). 

Mean Medical and Non-Medical Costs 

Mean medical and non-medical costs were categorized into 

six groups: hospital admission, CPO visits, visits to other 

healthcare professionals (HCP), productivity loss, other 

costs, and total costs. No significant differences in mean 

costs between groups were demonstrated in hospital 

admission, CPO visits, visits to other HCPs, combined costs 

for visits to HCPs and productivity loss (Table 3). In ‘other 

costs’, significantly higher costs for household care  

(p = 0.016) were found in the NMPK group compared to the 

MPK group. However, total costs were significantly higher 

for the MPK group (p < 0.001) mainly due to higher 

acquisition costs (Table 3). More detailed information is 

shown in Appendix III - Table A3. 

Outcome Measures 

A significant difference in the PEQ ambulation scale was 

observed between the NMPK and MPK. No significant 

differences were found on the remaining PEQ scales, as 

well as the EQ-5D-5L utility score and VAS score (Table 4). 

Table 1: Demographic characteristics of 111 participants 

categorized by type of prosthetic knee. 

 NMPK  
(n = 49) 

MPK  
(n = 62) 

p-value 

Age, (Mean ± SD) 67 ± 12 62 ± 14 0.027* 

Sex, n (%)a   0.953† 

• Female 16 (33) 21 (34)  

• Male 32 (65) 41 (66)  

Side of LLA, n (%)a   0.063 

• Left 17 (35) 33 (53)  

• Right 31 (63) 29 (47)  

Level of LLA, n (%)a   0.417 

• Transfemoral 33 (67) 38 (61)  

• Knee-Disarticulation 15 (31) 24 (39)  

Employment Status, n (%)a   0.246 

• Wage Employment 5 (10) 15 (24)  

• Self-Employed 6 (12) 7 (11)  

• Homemaker 6 (12) 5 (8)  

• Unemployed 1 (2) 0   

• Incapacity to Work 4 (8) 9 (15)  

• Retired 27 (55) 26 (42)  

Years Since Amputation, 
(Mean ± SD) 

28 ± 24 16 ± 18 0.005* 

Level of Educationa,b   0.324 

• Low 21 (43) 18 (29)  

• Middle 15 (30) 25 (40)  

• High 13 (27) 18 (29)  

New Prosthesis in Last 6 
Months, yes n (%) 

10 (20) 10 (16) 0.029* 

First Prosthesis, yes n (%) 13 (27) 3 (5) 0.001* 
 

NMPK: non-microprocessor-controlled knee; MPK: microprocessor-

controlled knee; SD: standard deviation; LLA: lower limb amputation 

a- Some variables have missing responses and therefore do not add up to 

100%  

b- Low: no education or lower vocational education; Middle: middle 

vocational education; High: higher education such as university of applied 

sciences or university (BSc/MSc) 

*- Significant at α < 0.05. 

†- This p-value indicates that there was no significant difference in the gender 

distribution between the two groups. 

 

Cost-Utility Analysis 

The mean cost difference after bootstrap was €14,626, with 

lower costs for the NMPK, and the mean QALY difference 

was 0.032 in favor of the MPK. This resulted in a mean 

incremental cost-utility ratio (ICUR) of €457,063 per QALY 

gained (Table 5). Most bootstrap replications fell within the 

NE quadrant (Figure 2, left panel), indicating higher utility 

and higher costs for the MPK compared to the NMPK. The 

cost-effectiveness acceptability curve in Figure 2 (right 

panel) demonstrates that the probability of the MPK being 

cost-effective does not exceed that of the NMPK until well 

over €400,000 per QALY, far above all willingness-to-pay 

thresholds (€20,000; €50,000 and €80,000).24 

 

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6 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

Table 2: Unit costs used in calculations. 

Unit Price/distance Source/remark 

Hospital Admission €644.00 

Guideline, no 
distinction 
general/university 
hospital 

Outpatient Visits  Dutch guidelines 

• CPO €120.00 
Guideline average 
price outpatient visit 

• Rehabilitation €120.00 
Guideline average 
price outpatient visit 

Visits Healthcare 
Professionals 

  

• General Practitioner €30.87 Guideline, per visit 

• Physiotherapist €38.89 Guideline, per visit 

• Occupational Therapist €24.32 Guideline, per visit 

• Social Worker €127.00 Guideline, per visit 

• Psychologist/Psychiatrist €109.80 
Guideline, average 
primary care and 
private 

• Occupational Health 
Physician 

€200.00 

Average price 
Occupational 
Health and Safety 
service 

Household Support and 
Informal Care 

  

• Household Help €32.76 Guideline, per hour 

• Personal Care €57.58 Guideline, per hour 

• Nursing Care €75.00 Guideline, per hour 

• Informal Care €18.80 Guideline, per hour 

Out Of Pocket Costs Real costs Guideline 

Paid Work   

• Friction Period (Days) 115 
Guideline, average 
past 5 years 

• Friction Period (Weeks) 16.4 
Guideline, average 
past 5 years 

• Productivity Cost/Hour €39.88 
Average for male 
and female, per 
hour 

Travel Costs  Dutch guidelines 

• Car €0.26 
Euro/km, parking 
costs € 3.00 per 
visit 

• Public Transport €0.21 Euro/km 

• Taxi €2.47 
Euro/km, start costs 
€ 3.36 per ride 

• Unknown €0.26 
Euro/km, car price 
applied 

Average Travel Distances   

• General Practitioner 1.1 km Guideline 

• Physiotherapist 2.2 km Guideline 

• Occupational Therapist 2.2 km 
Assumed same as 
physiotherapist 

• Social Worker 7.0 km 
Assumed same as 
hospital 

• Psychologist/Psychiatrist 7.0 km 
Assumed same as 
hospital 

• Occupational Health 
Physician 

3.7 km 
Average travel 
distance home to 
work 

• Hospital 7.0 km Guideline 

Prosthetic Knee Costs   

• MPK €21,018 Expert opinion 

• NMPK €4,417 Expert opinion 

 

Cost-Effectiveness Analysis 

The mean score for the PEQ-ambulation scale after 

bootstrap was 14.6 points higher for the MPK group 

compared to the NMPK group, resulting in a mean 

incremental cost-effectiveness ratio (ICER) of €1,020 per 

point gained (Table 5). Nearly all bootstrap replications fell 

within the NE quadrant, indicating higher self-reported 

walking ability and higher costs for the MPK compared to 

the NMPK (Figure 3-Top). Furthermore, 78.1% of bootstrap 

replications exceeded the minimal detectable change 

(MDC) of 11 points.42 

After the bootstrap, the mean score for the PEQ-utility scale 

was 5.4 points higher for the MPK group compared to the 

NMPK group, yielding a mean ICER of €2,757 per point 

gained (Table 5). Most bootstrap replications fell within the 

NE quadrant, indicating higher utility and higher costs for 

the MPK compared to the NMPK (Figure 3-Middle). Of all the 

bootstrap replications, 2.2% exceeded the MDC of 12 

points.42 

Lastly, a mean score difference of 4.5 points higher for the 

MPK group compared to the NMPK group was found on the 

PEQ-well-being scale after bootstrapping, resulting in a 

mean ICER of €3,308 per point gained (Table 5). The 

majority of the bootstrap replications fell within the NE 

quadrant, indicating better reported well-being and higher 

costs for the MPK compared to the NMPK (Figure 3-Bottom). 

Half a percent of the bootstrap replications exceeded the 

MDC of 14.42 

DISCUSSION 

This study demonstrates that the MPK is likely to provide 

higher scores of prosthesis-related and health-related QoL 

to its users compared to the NMPK, but at higher societal 

costs. The cost-effectiveness analyses yielded reasonable 

ICERs for prosthesis-related QoL ranging from €1,020 to 

€3,308, indicating that the costs to achieve a minimally 

detectable change is very reasonable and well within the 

willingness-to-pay threshold. However, based on the ICUR 

for health-related QoL, the MPK was determined not to be 

cost-effective. It is important to note that both the ICUR and 

ICER were based on short term measurements and as was 

shown in previous studies18,20,21 the ICUR will most likely be 

lower, making the MPK more cost-effective over a longer 

period of time.  

The significantly higher costs for the MPK were mostly 

driven by the higher acquisition costs, while the combined 

costs for visits to healthcare professionals were lower for 

this group compared to the NMPK group. As was shown in 

a previous study, the higher acquisition costs for the MPK 

will be balanced out after 19 months due to the lower 

healthcare costs related to falls.43 For clinicians and policy 

makers, this would mean that the higher initial costs are an 

investment that will lead to lower long-term costs and 

significant functional improvements for the prosthesis users.  

 

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7 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 3: Mean costs (in Euros) by category and type of prosthetic knee.  

 NMPK (N = 42) # MPK (N = 55) p-value 

Hospital admission       

• Direct Costs 184 (0, 0-7728) 46 (0, 0-1932) 0.754 

Outpatient visits       

• CPO 357 (142, 0-2148) 302 (249, 0-1351) 0.491 

Other HCP visits       

• General Practitioner 290 (0, 0-10605) 38 (0, 0-331) 0.921 

• Physiotherapist 130 (0, 0-1381) 335 (0, 0-2298) 0.106 

• Occupational Therapist 4 (0, 0-84) 3 (0, 0-140) 0.887 

• Social Worker 6 (0, 0-268) 12 (0, 0-669) 0.849 

• Psychologist/Psychiatrist 3 (0, 0-117) 26 (0, 0-886) 0.445 

• Occupational Health Physician 24 (0, 0-817) 4 (0, 0-206) 0.400 

• Combined HCP Visit Costs 458 (17, 0-10988) 418 (0, 0-2419) 0.081 

Other costs       

• Out of Pocket Costs 1094 (0, 0-20000) 1420 (0, 0-43000) 0.678 

• Household Care 1678 (0, 0-25657) 270 (0, 0-3407) 0.016* 

• Informal Care 822 (0, 0-13686) 1190 (0, 0-17597) 0.473 

Productivity loss       

• Friction Costs 368 (0, 0-15442) 161 (0, 0-4786) 0.483 

• Presenteeism 21 (0, 0-383) 101 (0, 0-3988) 0.769  

Total costs       

• Prosthesis (Fixed) 4417 21018  NA 

• Total Costs, Excluding Prosthesis 4981 (1308; 0-39340) 3909 (1376; 0-43108) 0.730 

• Total Costs, Including Prosthesis 9395 (5725, 4417-43757) 24927 (22394, 21018-64126) <0.001* 

Data presented as mean (median, min-max). Significance was tested using the Mann Whitney U test.  

NMPK: non-microprocessor controlled knee; MPK: microprocessor controlled knee; CPO: certified prosthetist/orthotist; NA: not applicable. 

* Significant at α < 0.05. # In tables presenting statistical results, the number of participants depends on the available complete data. 

Table 4: Scores EQ-5D-5L and PEQ.  

 NMPK (N = 49) MPK (N = 60)* Mean difference p-value 

EQ-5D-5L utility 0.742 0.787 0.045 (-0.028 to 0.118) 0.225 

EQ-5D-5L VAS 73.5 78.3 4.78 (-3.58 to 13.1) 0.259 

PEQ-AM 52.0 67.0 15.0 (–6.0 to 24.0) 0.001 

PEQ-UT 69.2 74.0 4.8 (-1.8 to 11.5) 0.154 

PEQ-WB 72.8 76.3 3.4 (-4.7 to 11.5) 0.402 

VAS: visual analogue scale; PEQ-AM: prosthesis evaluation questionnaire ambulation scale; PEQ-UT: prosthesis evaluation questionnaire utility scale; PEQ-WB: 

prosthesis evaluation questionnaire well-being scale; * N=58 for EQ-5D-5L 

Table 5: ICUR and ICER calculation.  

 NMPK (N = 46) MPK (N = 55)* P-value Mean difference† ICUR/ICER‡ 

QALY 0.37 0.40 0.08 0.03 (-0.04 to 0.09) 457,063 

PEQ-AM 53.3 67.9 0.002 14.6 (1.1 to 30.5) 1,020 

PEQ-UT 69.4 74.9 0.11 5.4 (-7.7 to 16.7) 2,757 

PEQ-WB 72.8 77.4 0.27 4.5 (-10.7 to 18.5) 3,308 

ICUR: incremental cost-utility ratio; ICER: incremental cost-effectiveness ratio; NA: not applicable; PEQ: prosthesis evaluation questionnaire; AM: ambulation; UT: 

utility; WB: well being; * N=52 for QALY; † Mean difference after bootstrap;  ‡ ICUR/ICER calculated with mean cost difference of €14,626 after bootstrap; 

ICUR/ICER were calculated based on population that completed the PEQ/EQ5D and had costs. 

 

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8 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

Mean Costs and Medical Consumption 

The significant difference in total costs between MPK and 

NMPK was mainly driven by the fixed high acquisition costs 

of MPK (€21,018) compared to NMPK (€4,417). This is 

similar to previous studies.18,20,22 However, a recent study 

demonstrated that while the MPK’s acquisition costs 

exceeded those of the NMPK, this would offset after 19 

months due to lowered healthcare costs related to falls.43 

When excluding the acquisition costs, total costs were 

higher for NMPK (Table 3). Higher costs for the NMPK group 

were related to higher combined costs for visits to HCPs and 

higher costs for household care. While this study did not 

investigate the specific causes for visits to HCPs, one study 

demonstrated that the medical costs for fall-related 

incidents were 2.67 times higher for NMPK users compared 

to MPK users, which made up 46% of the total costs for this 

group.22 Previous studies have demonstrated that the use 

of an MPK can result in a significant decrease in falls 

compared to an NMPK, which could substantiate the 

findings4,6,8,10,13,44 Therefore, it would be valuable for future 

research to examine the specific fall-related costs in more 

detail, as this could provide further insight into the economic 

impact of the MPK compared to the NMPK. 

Furthermore, MPK users demonstrated higher 

presenteeism and lower friction costs. These findings 

support earlier studies reporting decreased household costs 

and less productivity loss with MPK compared to the 

NMPK.23 Recently, a Dutch study demonstrated significant 

improvements in participation with MPK use compared to 

NMPK,10 which could explain the reduced need for 

household care and lower work absence.  

Outcome Measures 

The MPK group showed significantly higher scores on the 

PEQ ambulation scale compared to the NMPK group. This 

aligns with other studies reporting significant improvements 

in walking ability with MPK, including walking distance, 

speed, and terrain navigation,11,45 as well as self-reported 

walking ability.4,45  

No significant differences were found on both the utility 

score and VAS score of the EQ-5D-5L between the MPK 

and NMPK, which contrasts earlier findings.20,21 

Additionally, no significant differences were found in the 

utility and well-being scales of the PEQ, which contradicts 

previous studies that reported significantly higher scores on 

these scales for MPK users.10,12,45,46 The disparity could 

stem from methodological differences, since participants in 

this study were assessed using their own prosthesis without 

an intervention, preventing direct comparison between the 

MPK and NMPK. Participants in both groups may have 

been generally content with their current prostheses, 

resulting in no significant differences.   

Cost-Utility Analysis 

Based on the ICUR, the MPK was not cost-effective 

compared to NMPK. Most bootstrap replications indicated 

improved QoL with MPK, but costs were higher, exceeding 

all willingness-to-pay thresholds. Our mean ICUR was 

€457,063 per QALY gained, more than ten times higher 

than other studies, which reported ICURs ranging from 

€3,21815 to €40,155.20 One study stratified participants into 

three groups based on age at enrolment; age at first 

prosthesis; and years of experience using a prosthesis, 

 

Figure 2: Left panel: Cost-effectiveness plane (CE-plane) showing the distribution of bootstrap replications for the differences between costs 

and effects of the MPK versus the NMPK. Blue dots indicate how many of the 5000 replications fall in the respective quadrants. The CE-

plane is divided into the north-east (NE) quadrant, the north-west (NW) quadrant, the south-west (SW) quadrant and the south-east (SE) 

quadrant. Replications in these quadrants represent the following results: NE (better health outcomes, higher cost), NW (worse health 

outcomes, higher cost), SE (better health outcomes, lower cost), and SW (worse health outcomes, lower cost). Right panel: Cost-

effectiveness acceptability curve (CEAC) showing the probability of cost-effectiveness of the MPK and NMPK at increasing values of the 

ceiling ratio for willingness-to-pay for a QALY gained. 

Mean Incremental QALY 6 Months Values of Ceiling Ratio 

M
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Probability NMPK Cost-Effective 

 

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9 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

yielding ICURs between €28,269 and €88,779,20 but even 

the highest ICUR was much lower than ours. Mean 

incremental cost differences in other studies ranged from 

€7,657 to €18,431,18,20,21 comparable to our €14,626. 

 

 

 

Figure 3: Cost-effectiveness planes (CE-planes) showing the distribution of bootstrap replications for the differences between costs and 

effects of the MPK versus the NMPK on the PEQ ambulation scale (top panel); PEQ utility scale (middle panel); PEQ well-being scale (bottom 

panel). MDC: minimal detectable change. The CE-plane is divided into the north-east (NE) quadrant, the north-west (NW) quadrant, the 

south-west (SW) quadrant and the south-east (SE) quadrant. Replications in these quadrants represent the following results: NE (better 

health outcomes, higher cost), NW (worse health outcomes, higher cost), SE (better health outcomes, lower cost), and SW (worse health 

outcomes, lower cost). 

Mean Incremental PEQ-AM Score 

 

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Mean Incremental PEQ-UT Score 

Mean Incremental PEQ-WB Score 

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10 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

However, QALYs gained with the MPK in other studies were 

much higher (0.42 – 2.38) than our finding of 0.032.18,20-22 

Methodological differences likely explain the variance in 

results. Firstly, the six-month timeframe in this study 

contrasts with other studies' 5-year,20,21 8-year18 or even 25-

year22 periods. Longer follow-up with sustained 

improvement of QoL with the MPK is likely to result in larger 

QoL differences compared to the NMPK. Simultaneously, 

higher acquisition costs of the MPK could be compensated 

by lower healthcare consumption if measured over a longer 

period of time.  

Furthermore, not all studies included the same costs. Our 

study included acquisition, direct, and indirect medical costs 

and productivity loss, whereas other studies limited costs to 

acquisition and maintenance,18 did not specify costs for 

HCPs other than the general practitioner,21 or analyzed 

acquisition, maintenance, and transportation costs but did 

not specify them.20 The lack of specific cost insights in other 

studies prevents direct comparison to further clarify the 

ICUR difference.  

Cost-Effectiveness Analysis 

The ICERs based on prosthesis-related outcomes indicated 

that the MPK could result in better QoL at acceptable costs 

per unit of improvement compared to the NMPK. However, 

formal thresholds for acceptability of these cost differences 

for a unit of improvement are not available, so this remains 

arbitrary. Although a direct comparison with a formal 

threshold is not possible, it is worth noting that due to the 

fairly low ICERs, the costs associated with achieving the 

MDCs for each PEQ scale can be considered reasonably 

priced. E.g. the costs to achieve the MDC of 11 points for 

the PEQ ambulation scale would cost €11,215. In this study, 

we demonstrated a significant difference in score on the 

PEQ-ambulation scale, which exceeded the MDC in 78.1% 

of the bootstrap replications. This is comparable to previous 

studies that investigated the differences in walking ability 

between the MPK and NMPK4,12,21,45,47 While we did not find 

significant differences in the other PEQ-scales, other 

studies using intervention designs with a within-subject 

comparison did report significant differences on these 

scales.10,12,45,46 This design difference may explain the 

variation in outcomes. 

Limitations 

This study had several limitations. Firstly, we only 

considered the cost of the prosthetic knee unit, excluding 

other parts of the prosthesis such as the socket, pylon and 

foot, which may result in an underestimation of the total 

cost. Moreover, we were unable to obtain prosthesis costs 

at the individual level, leading to absence of variation in 

prosthesis cost as a major component of total costs. 

Additionally, prosthesis users differed between those using 

an NMPK or an MPK, with variations in age, activity level, 

and health status potentially influencing the outcomes and 

generalizability of the findings. Lastly, our non-intervention 

design did not allow for direct comparison between the 

NMPK and MPK.  

CONCLUSION 

The cost-effectiveness analyses demonstrated that the 

MPK is likely to improve prosthesis-specific QoL, but at 

higher costs. However, short-term (6 months) improvement 

in health-related QoL was too small to result in substantial 

QALY gain to offset the higher costs of the MPK and result 

in an incremental cost-utility ratio below the generally 

accepted willingness-to-pay thresholds.  

ACKNOWLEDGEMENTS 

The authors would like to express their sincere gratitude to OIM 

orthopedie and Livit orthopedie for their support in participant 

recruitment and survey distribution. Furthermore, we would like to 

thank all participants for their time and valuable contributions to this 

study. 

DECLARATION OF CONFLICTING INTERESTS 

The authors declare no conflicts of interest. The funders had no role 

in the design of the study; in the collection, analyses or 

interpretation of data; in the writing of the manuscript; or in the 

decision to publish the results. 
 

AUTHORS’ CONTRIBUTION 

• Charlotte E. Bosman: Conceptualization, Methodology, 
Formal Analysis, Investigation, Data Curation, Writing Original 
Draft, Review & Editing, Visualization, Project Administration.  

• Corry K. van der Sluis: Conceptualization, Methodology, 
Review & Editing, Funding Acquisition.  

• Aline H. Vrieling: Conceptualization, Methodology, Review & 
Editing, Funding Acquisition. 

• Jan H.B. Geertzen: Review & Editing, Funding Acquisition. 

• Bregje L. Seves: Methodology, Review & Editing.  

• Henk Groen: Conceptualization, Methodology, Formal 
Analysis, Data Curation, Review & Editing, Visualization. 

All authors read and approved the final manuscript. 

SOURCES OF SUPPORT 

This study was funded by ZonMW as part of a larger research 

project entitled ‘Effectiveness and cost-effectiveness of lower limb 

prostheses’ (project number: 853001109; URL: 

https://projecten.zonmw.nl/nl/project/doelmatige-zorg-van-

beenprothesen). 

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https://projecten.zonmw.nl/nl/project/doelmatige-zorg-van-beenprothesen
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Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

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12 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

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13 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

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14 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

APPENDICES 

Appendix I – English translation of the cost-questionnaire 

 
Question 1. What was your occupation during the past 6 months? 

................................................................................................................................... 

Question 2. How many hours per week did you work during the past 6 months? Only count the hours for which you were paid. 

………… hours 

 

Question 3. How many days per week did you work during the past 6 months? ………… days 

 

Question 4. Have you been absent from work due to illness during the past 6 months? This refers to absence or sick leave related to 

your prosthesis or amputation. 

 

 No  

 Yes, I was unable to work for the entire 6 months 

 Yes, I was absent for approximately ….. days  (Only count the working days in the past 6 months) 

If you checked ‘’Yes,’’ please answer question 5. Otherwise, continue with question 7. 

 

Question 5. Were you absent from work for more than 4 consecutive weeks due to illness during the past 6 monts?  

 No 

 Yes 

If you checked ‘’Yes,’’ please answer question 6. Otherwise, continue with question 7. 

 

Question 6. How long were you ill for? This refers to absence or sick leave related to your prosthesis or amputation. 

Approximately …… weeks 

 

Question 7. Were there days during the past 6 months when you worked but experienced physical or psychological problems 

during work? This refers to complaints related to your prosthesis or amputation. 

 

 No 

 Yes 
 

If you checked ‘’Yes,’’ please answer question 8 and 9. Otherwise, continue with question 10. Please read the explanation above question 10 
first. 
 

Question 8. On how many working days did you experience physical of psychological problems during work? Only count the 

working days in the past 6 months.  Approximately …… working days 

 

Question 9. On the days you experienced problems, you may not have been able to work as much as usual. How much work could 

you do on those days on average? Refer to the scale below. 10 means you could work as much as usual. 0 means you could do nothing. 

Circle the appropriate number.  

 
I could do nothing 
on those days 

 I could do about 
half 

 I could do as 
much as usual 

  

0 1 2 3 4 5 6 7 8 9 10 

The following questions are about your job. That means work for which you are paid. The questions refer to the job you held 

during the past 6 months. If you do not have a paid job, please continue with question 10. Be sure to read the explanation 

above question 10 first. 

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15 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

 
Question 10. Were there days during the past 6 months when you could do less unpaid work due to physical or psychological 
problems? This refers to problems related to your prosthesis use during the past 6 months. 

 No 

 Yes 

If you checked ‘’Yes,’’ please answer question 11. Otherwise, continue with question 12. 
 
Question 11. On how many days did this occur? Only count the days in the past 6 months 

…… days 

 

 
 
Question 12. Have you been admitted to a rehabilitation center during the past 6 months? 

 No admission 

 ….. days of admission 

 

Question 13. How many appointments did you have with your general practitioner or practice nurse during the past 6 months?  

 No appointments 

 ….. appointments 

 

Question 14. How many appointments did you have with a social worker during the past 6 months? 

 No appointments 

 ….. appointments 

  

Explanation for question 10 and 11: Unpaid work 

You may also experience physical or psychological problems with unpaid work. 

Sometimes this means you can do less. For example, you may struggle to care for your children, do volunteer work, go grocery shopping, 

or work in the garden. The following questions are about this.   

Ook bij onbetaald werk kunt u last hebben van uw lichamelijke of psychische problemen. Soms kunt u daardoor minder doen. U kunt 

bijvoorbeeld niet goed voor de kinderen zorgen of vrijwilligerswerk doen. Of geen boodschappen doen of in de tuin werken. Daarover 

gaan de volgende vragen. 

Explanation 

We would like to know which doctors you had appointments with during the past 6 months. These should be appointments 

for yourself. Other healthcare providers also count. For example, appointments with a physical therapist or CPO/prosthetist. 

Which appointments count? 

• Check-ups 

• Appointments due to physical or psychological complaints 

• Home visits by a doctor 

• Telephone appointments 

• Calls to the prescription line 

What appointments do not count? 

• Appointments for someone else, such as your partner or child 

• Calls to schedule an appointment 

If you’re not sure how many appointments you had, please write down an approximate number.  

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Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

Question 15. How many appointments did you have with you prosthetist/CPO? 

 

 No appointments 

 ….. appointments 

 
Question 16. How many appointments did you have with a physical therapist during the past 6 months? Or with a Caesar therapist, 

Mensendieck therapist, or manual therapist? Only count appointments outside of the hospital or rehabilitation center. Add all 

appointments with these therapists together.  

 No appointments 

 ….. appointments 

 

Question 17. How many appointments did you have with an occupational therapist during the past 6 months? Only count 

appointments outside the hospital or rehabilitation center. 

 No appointments 

 ….. appointments 

 

Question 18. How many appointments did you have with a psychologist, psychotherapist or psychiatrist during the past 6 
months? Only count appointments outside of the hospital or rehabilitation center. Add all appointments with these professionals together 

 No appointments  

 ….. appointments 

 

Question 19. How many appointments did you have with an occupational health physician during the past 6 months? 

 No appointments 

 ….. appointments 

 
Question 20a. Have you received home care during the past 6 months? This only refers to support or care received in connection with 

your prosthesis or amputation.  

 No 

 Yes 

If you checked ‘’Yes,’’ please answer question 20b through 20d. Otherwise, continue with question 21. 

 

Question 20b. What type of home care did you receive during the past 6 months? 

 Household help 

e.g., vacuuming, making the bed, grocery shopping 

 

 Personal care 

e.g., help with showering or dressing 

 

 Nursing care 

e.g., applying bandages, administering medication, measuring blood pressure 

 
Question 20c. How many weeks did you receive this home care? Add up all weeks in the past 6 months. Note: a 6-month period equals 

26 weeks. 

 
Household help:    ….. weeks  

Personal care:    ….. weeks  

Nursing care:    ….. weeks  

 

 

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Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

Question 20d. How many hours of home care did you receive on average during these weeks? 

 

Household help:                     Average ….. hours per week 

Personal care:     Average ….. hours per week 

Nursing care:     Average ….. hours per week 

 
Question 21a. Have you received help from a family member or acquaintance during the past 6 months due to physical or 
psychological problems? This refers only to help received in connection with your prosthesis or amputation.  

 No 

 Yes 

If you checked ‘’Yes,’’ please answer question 21b through 21d. Otherwise, continue with question 22. 

 

Question 21b. What type of help did you receive from family members or acquaintances during the past 6 months? You may check 

more than one box 

 Household help 

e.g., vacuuming, making the bed, grocery shopping, preparing food and drinks, caring for children 

 

 Personal care 

e.g., help with showering or dressing, help with eating and drinking, administering medication 

 

 Practical help 

e.g., support with walking, outings or visits to acquaintances, visits to the doctor or hospital, arranging help or financial matters 
 

Question 21c. How many weeks did you receive this home care? Add up all weeks in the past 6 months. Note: a 6-month period equals 

26 weeks. 

Household help:                     ….. weeks  

Personal care:     ….. weeks  

Practical help:     ….. weeks  

 
Question 21d. How many hours of home care did you receive on average during these weeks? 

Household help:                    Average ….. hours per week 

Personal care:     Average ….. hours per week 

Practical help:     Average ….. hours per week 

 

Question 22. Have you or your family members spent extra money in the past 6 months on any of the following items? These 

expenses are related to your prosthesis or amputation 

 

Category No Yes Estimated amount (€) 

Repairs of the prosthesis at own expense   € 

Home modifications at own expense   € 

Assistive devices at own expense   € 

Modifications to vehicles at own expense (car, 
bike, motorcycle) 

  € 

Equipment for hobbies/sports at own expense   € 

Other, namely 
…………………… 
 

  € 

 
 
 
 
  

https://doi.org/10.33137/cpoj.v8i2.45823


 

18 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

 
 
Question 23. What means of transportation did you use to travel from home to the hospital, rehabilitation center, or 
CPO/prosthetist?  
 

 Not applicable 

 Walking 

 Bicycle 

 Car 

 Wheelchair or mobility scooter 

 Public transport 

 Taxi 

 Other, namely ……………………………………………………………………… 

 
Question 24. What is the one-way distance between your home and the hospital, rehabilitation center, and CPO/prosthetist?  
 
Hospital:                      ….. kilometer 

Rehabilitation center:   ….. kilometer 

CPO/prosthetist:                   ….. kilometer 

 
Do you have any questions or comments? 

If you have any questions or comments, please write them down below.  

……………………………………………………………….………………………………… 

……………………………………………………………….………………………………… 

……………………………………………………………….………………………………… 

……………………………………………………………….………………………………… 

……………………………………………………………….………………………………… 

……………………………………………………………….………………………………… 

 

 

  

Explanation 

The following questions are about expenses incurred in connection with visits to the hospital, rehabilitation center and 

CPO/prosthetist. 

 

https://doi.org/10.33137/cpoj.v8i2.45823


 

19 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

Appendix II - Calculation of burden of disease   

The severity of an illness or condition can be expressed in a burden of disease score between 0 and 1. The different willingness-to-pay 
thresholds (WTP) are based on this score (Table A1).24 

Table A1: Willingness-to-pay thresholds in the Netherlands. 

Burden of disease Reference threshold for maximum additional cost per QALY 

0,1 – 0,4 Up to €20,000 per QALY 

0,41 – 0,7 Up to €50,000 per QALY 

0,71 – 1,0 Up to €80,000 per QALY 

 QALY: quality adjusted life year 

 

 

The burden of disease is calculated with the following equation: 

 

(𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝑄𝐴𝐿𝑌𝑠 𝑤𝑖𝑡ℎ𝑜𝑢𝑡 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛 − 𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝑄𝐴𝐿𝑌𝑠 𝑤𝑖𝑡ℎ 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛)

𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝑄𝐴𝐿𝑌𝑠 𝑤𝑖𝑡ℎ 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛
  

 

Remaining QALYs in a specific health state are calculated by multiplying the EQ-5D-5L index score by the remaining number of years in that 
health state.  

To assess the burden of disease associated with lower limb amputation (LLA), we compared the health-adjusted life expectancy between the 
general population in the Netherlands and persons with peripheral vascular disease (PVD), the primary underlying condition in this study 
population.48 The average life expectancy of the general population is 85.5 years,49 while individuals with PVD have an estimated life 
expectancy of 81.5 years.50 

The average EQ-5D-5L index score for the general population of the Netherlands was 0.86935 which is in line with the index scores of 
comparable countries that ranged from 0.82 to 0.90.51-54 For the LLA population, EQ-5D-5L index scores ranged from 0.462 to 0.531.37 

The average age at amputation was estimated at 67 years, based on available cohort data.  

Based on these parameters, we calculated the burden of disease across three scenarios, yielding a range of 0.48 to 0.60 (Table A2). Given 
that the range of burden of disease falls within the Dutch WTP of €50,000 for a burden of disease between 0.41 and 0.70, this threshold is 
considered appropriate for evaluating interventions in the LLA population. 

 

Table A2: Burden of disease scores. 

 

  
Burden of disease 
score 

1 Smallest possible difference in EQ-5D-5L index score 0,48 

2 Largest possible difference in EQ-5D-5L index score 0,60 

3 Best fitting variables for LLA population 0,50 

 

 

 

 

 

 

https://doi.org/10.33137/cpoj.v8i2.45823


 

20 

Bosman C.E, van der Sluis C.K, Vrieling A.H, Geertzen J.H.B, Seves B.L, Groen H. Health economic evaluation of microprocessor and non-microprocessor 
controlled prosthetic knees. Canadian Prosthetics & Orthotics Journal. 2025; Volume 8, Issue 2, No. 3. https://doi.org/10.33137/cpoj.v8i2.45823  

CANADIAN PROSTHETICS & ORTHOTICS JOURNAL 

ISSN: 2561-987X ECONOMIC EVALUATION OF MICROPROCESSOR VS. NON-MICROPROCESSOR KNEES 

Bosman et al., 2025 

Appendix III 

Table A3: Detailed costs (in Euros) and volumes by category and knee type. 

 NMPK (N=44) MPK (N=58) 

Outpatient visits     

CPO   

Direct costs (€) 253.6 (n=29) 263.2 (n=45) 

Travel costs (km) 93.2 (n=28) 51.7 (n=42) 

Other HCP visits     

Direct costs (€)   

   General practitioner 74.4 (n=19) 36.2 (n=25) 

   Physiotherapist 99.8 (n=13) 293.0 (n=26) 

   Occupational therapist 2.76 (n=2) 2.52 (n=2) 

   Social worker 5.77 (n=1) 10.9 (n=1) 

   Psychologist/psychiatrist 2.50 (n=1) 20.8 (n=3) 

   Occupational health physician 22.7 (n=2) 3.44 (n=1) 

Travel costs combined (€) 205.2 (n=22) 58.6 (n=37) 

Other costs     

Out of pocket costs (€) 1047 (n=17) 1407 (n=25) 

Household care (h)   

   Household work 1434 (n=13) 461.5 (n=6) 

   Personal care 704 (n=4) n=0 

   Nursing care n=0 n=0 

Informal care (h) 2357 (n=14) 3591 (n=16) 

Productivity loss     

Friction costs (€) 524.8 (n=1) 226.7 (n=3) 

Presenteeism (€) 21.9 (n=4) 142.3 (n=3) 

NMPK: non-microprocessor controlled knee; MPK: microprocessor controlled 
knee; CPO: certified prosthetist/orthotist 

 

 

 

 

 

https://doi.org/10.33137/cpoj.v8i2.45823

