Selecting, Administering, and Interpreting Outcome Measures among Adults with Lower-Limb Loss: An Update for Clinicians

Evaluating the Usability and Equivalence of Electronic Patient-Reported Outcome Measures for Individuals with a Lower-Limb Amputation

Introduction

Electronic versions of patient-reported outcome measures (PROMs) seem to have a clear administrative logging advantage to traditional paper versions. However, most of them have not been formally evaluated for their suitability to replace paper outcome measures for assessment of individuals with lower-limb amputations. The aim of this study is to examine the usability and equivalence of electronic to paper versions of PROMs suitable for use in prosthetic clinical care and research for persons with lower-limb loss.

Methods

In this cross-sectional study, 10 participants remotely completed the following PROMs online and then on paper: Orthotic and Prosthetic User Survey (OPUS), Modified Falls Efficacy Scale (MFES), Prosthetic Evaluation Questionnaire (PEQ), Patient Health Questionnaire–9 (PHQ-9), and Community Participation Indicators (CPI). Participants also answered open-ended and standardized questions regarding the usability of the electronic surveys. Wilcoxon signed rank tests, comparisons to minimum detectable change, intraclass correlation coefficients, and Bland-Altman plots were used to evaluate differences between the two survey versions, meaningful changes in scores, reliability, and systematic biases, respectively.

Results

Electronic surveys had fewer missing or ambiguous responses than paper surveys; however, the PEQ Social Burdens subscale could not be evaluated due to error in the creation of the electronic survey. No significant differences were found between scores of the two versions for any of the measures, but multiple participants had meaningful changes in the Appearance and Sounds PEQ subscales. All measures demonstrated acceptable reliability between versions, except the Appearance, Perceived Response, and Sounds subscales of the PEQ. No systematic biases in scores or usability concerns were found for any measures.

Conclusions

This study analysis showed that most of the electronic PROMs studied are easily used and demonstrate equivalence to the paper versions. However, the PEQ Appearance, Perceived Response, Sounds, and Social Burden subscales require further evaluation.

Clinical Relevance

Except for the PEQ, electronic versions of the PROMs in this study can likely be used interchangeably with paper versions among individuals with lower-limb loss.

Rehabilitative outcomes with preparatory suction prostheses following traumatic Gritti-Stokes amputation: A case series

Gritti-Stokes amputation (GSA) is a knee disarticulation variant, where the femur is transected at the level of the epicondyle and the patella is fixated to the distal end. GSA results in a long residual limb with little postoperative swelling and less potential for muscular atrophy, so stable limb volume may allow the use of seal-in suction for suspension for preparatory prostheses. The purpose of this case series was to report on the efficacy of seal-in suction preparatory prostheses for 2 adults with traumatic GSA. Between October and December of 2021, 2 participants with unilateral traumatic Gritti-Stokes amputation, who had received seal-in suction suspension for their preparatory prostheses, were recruited. Information was extracted from medical charts regarding prosthetic care and mobility at preparatory and definitive prosthesis evaluation, and participants underwent standardized measurement of their residual limb and prosthesis. Duration of preparatory prosthesis use was >6 months; neither participant reported loss of suspension nor significant complications with socket fit. Participant 1 required socket replacement because of residual limb pain secondary to osteophyte formation, and Participant 2 required component replacement because of weight gain. At definitive prosthesis evaluations, both participants were unlimited community ambulators; both successfully returned to work before provision of their definitive prostheses. Results indicate that seal-in suction suspension may be viable for preparatory prostheses among adults with traumatic GSA, but knee center height discrepancies persist. GSA may yield highly functional outcomes for adults with traumatic amputation. Further research is required to substantiate these findings.

Convergent construct validity of the Brazilian version of the Houghton scale

BACKGROUND

After lower limb amputations, a decrease in gait capacity, even with prostheses, is common and persistent. Functional ability involves multiple constructs; therefore, several outcome measures, such as performance tests or self-report questionnaires, should be used to evaluate people with amputation who use prostheses.

OBJECTIVE

To analyze the convergent construct validity of the Brazilian version of the Houghton scale in a sample of lower limb prosthesis users.

METHODS

Volunteers selected were older than 18 years with any level of lower limb amputation and prosthesis use for at least 6 months. In this study, evidence of construct validity of the Houghton scale was established by the Spearman rho correlation with the Brazilian translation of the Prosthetic Limb Users Survey of Mobility and with the Physical Function (PF) and Emotional Well-being subdomains of the Medical Outcomes Study 36-Short Form Health Survey.

RESULTS

Seventy-one volunteers were recruited for the study. The sample consisted mainly of men (70.4%) with a mean age of 50 ± 12 years. The primary cause of amputation was traumatic (53.5%), and most participants (54.9%) had a transtibial amputation. The Houghton questionnaire correlated strongly with the Brazilian translation of the Prosthetic Limb Users Survey of Mobility questionnaire (rho: 0.74, p < 0.01) and weakly with the PF and Emotional Well-being of the 36-Short Form Health Survey (rho: 0.06 and rho: 0.22, respectively, p > 0.05).

CONCLUSION

This study showed evidence of convergent construct validity of the Houghton questionnaire to measure and classify functional use of lower limb prostheses, with great value to clinical practice. Additional work is needed to assess other measurement properties in different samples.

The Effect of Advanced Age on Prosthetic Rehabilitation Functional Outcomes in People With Lower Limb Amputations: A Retrospective Chart Audit of Inpatient Admissions

OBJECTIVE

To evaluate the effect of age on functional outcomes at discharge from prosthetic rehabilitation.

DESIGN

Retrospective chart audit.

SETTING

Rehabilitation hospital.

PARTICIPANTS

Individuals ≥50 years with a transtibial level lower limb amputation (LLA) and above admitted to the inpatient prosthetic rehabilitation program from 2012 to 2019 (n=504). A secondary analysis included a subset of matched participants (n=156).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The L-Test of Functional Mobility (L-Test), 2-Minute Walk Test (2MWT), 6-Minute Walk Test (6MWT), and Activities-specific Balance Confidence scale.

RESULTS

A total of 504 participants (66.7±10.1 years) met the inclusion criteria, 63 participants (84.9±3.7 years) were part of the oldest old group. The sample was stratified into 4 age groups (50-59, 60-69, 70-79, and 80+) for data analysis. The analysis of variances were statistically significant for all outcome measures (P<.001). Post-hoc testing for the L-Test, 2MWT, and 6MWT demonstrated that the oldest old had significantly reduced performance compared with people 50-59 years old (P<.05), but there were no significant differences between the oldest old and the 60-69 [(L-Test, P=.802), (2MWT, P=.570), (6MWT, P=.772)] and 70-79 [(L-Test, P=.148), (2MWT, P=.338), (6MWT, P=.300)] age groups. The oldest old reported significantly lower balance confidence compared with all 3 age groups (P<.05).

CONCLUSION

The oldest old achieved similar functional mobility outcomes as people 60-79 years, the most common age group of people with an LLA. Advanced age alone should not disqualify individuals from prosthetic rehabilitation.

Rasch validation of the German translation of the Prosthetic Limb Users Survey of Mobility short forms in people with lower limb amputation

BACKGROUND

Prostheses are a primary rehabilitative intervention for people after lower limb amputation. To appropriately measure the effectiveness of prosthetic interventions, valid and reliable measures of prosthetic mobility are required. The Prosthetic Limb Users Survey of Mobility (PLUS-M) is a promising instrument for measuring prosthesis users' mobility. However, German translations of the PLUS-M short forms have not yet been validated.

OBJECTIVES

Rasch validation of the German translation of the PLUS-M short forms in people with lower limb amputation.

STUDY DESIGN

This study is based on a cross-sectional survey of prosthesis-using lower limb amputees from a nation-wide cohort.

METHODS

PLUS-M data (the 7-item and the 12-item shortforms; PLUS-M-7 and PLUS-M-12, respectively) from 194 lower limb prosthesis users were subjected to Rasch analysis, an advanced statistical method for assessing if the measurement properties of a questionnaire comply with a wide spectrum of psychometric requirements.

RESULTS

Analysis showed appropriate rating scale functioning, good internal construct validity (item fit), unidimensionality, and good targeting of the PLUS-M-7 and PLUS-M-12 short forms. Moreover, the greater conditional measurement precision of PLUS-M-12 (regarding higher test information and lower standard error of mobility estimates) was quantified.

CONCLUSIONS

Rasch analysis of the German translation of both PLUS-M short forms showed good psychometric qualities. In addition, our study showed that test scores from the PLUS-M-12 are more accurate. Therefore, the PLUS-M-12 is recommended for individual-level clinical applications (e.g., classification or change assessment).

Head-to-head Rasch comparison of the Prosthesis Evaluation Questionnaire-Mobility Section and the Prosthetic Mobility Questionnaire 2.0 in Italian lower-limb prosthesis users

BACKGROUND

The Prosthesis Evaluation Questionnaire-Mobility Section (PEQ-MS) and the Prosthetic Mobility Questionnaire (PMQ 2.0) are two validated self-report questionnaires assessing mobility in people with lower-limb amputation.

OBJECTIVE

The aim of this study was to assess and compare the psychometric properties of PEQ-MS and PMQ 2.0 in a sample of 100 Italian lower-limb prosthesis users.

METHODS

We conducted a secondary Rasch analysis of data from a prospective single-group observational study, comparing the PEQ-MS and PMQ 2.0 head to head and then cocalibrating them onto a common interval-scaled metric, through common-person equating, to compare their operational range.

RESULTS

The PMQ 2.0 showed good measurement qualities. The PEQ-MS had acceptable psychometric properties, despite some weakness in item selection. Cocalibration of the two questionnaires indicated that they assess the same underlying construct (prosthetic mobility), but PMQ 2.0 items have a wider range of difficulty (by one logit). Finally, we created a nomogram allowing to "cross-walk" between scores of the two questionnaires.

CONCLUSIONS

Comparison of the two questionnaires showed that the PMQ 2.0 has a better measurement performance and larger operational range than the PEQ-MS, making it more suitable for assessing lower-limb prosthesis users with a large range of locomotor abilities, in particular those with higher mobility levels.

Comparison of prosthetic mobility and balance in transfemoral amputees with bone-anchored prosthesis vs. socket prosthesis

BACKGROUND

The literature comparing bone-anchored prosthesis (BAP) with socket prosthesis (SP) consistently reports improvement in physical health and quality of life using primarily patient-reported outcome measures (PROMs).

OBJECTIVE

To determine the differences in mobility and balance using performance-based outcome measures and PROMs in people with transfemoral amputations (TFAs) fitted with BAP vs. SP.

STUDY DESIGN

Causal comparative.

METHODS

Two groups of people with TFAs were recruited: one using a BAP (N = 11; mean age ± standard deviation, 44 ± 14.9 years; mean residual limb length as a percentage of the intact femur, 68% ± 15.9) and another group using a SP (N = 11; mean age ± standard deviation, 49.6 ± 16.0 years; mean residual limb length as a percentage of the intact femur, 81% ± 13.9), and completed the 10-meter walk test, component timed-up-and-go, Prosthetic Limb Users Survey of Mobility™ 12-item, and Activities-specific Balance Confidence Scale.

RESULTS

There were no statistically significant differences between the BAP and SP groups in temporal spatial gait parameters and prosthetic mobility as measured by the 10-meter walk test and component timed-up-and-go, yet large effect sizes were found for several variables. In addition, Activities-specific Balance Confidence Scale and Prosthetic Limb Users Survey of Mobility™ scores were not statistically different between the BAP and SP groups, yet a large effect sizes were found for both variables.

CONCLUSIONS

This study found that people with TFA who use a BAP can demonstrate similar temporal spatial gait parameters and prosthetic mobility, as well as self-perceived balance confidence and prosthetic mobility as SP users. Therefore, suggesting that the osseointegration reconstruction surgical procedure provides an alternative option for a specific population with TFA who cannot wear nor have limitations with a SP. Future research with a larger sample and other performance-based outcome measures and PROMs of prosthetic mobility and balance would further determine the differences between the prosthetic options.

Association between measures of cognitive function on physical function in novice users of a lower limb prosthesis

BACKGROUND

Cognitive impairment is prevalent in people with lower limb amputations (PLLA) and is associated with adverse outcomes, such as falls and worse rehabilitation outcomes. Physical function tests are essential to examine abilities; however, no research in PLLA has clarified the magnitude of cognitive demands amongst available tests in users novice at walking with a prosthesis.

RESEARCH QUESTION

Is there an association between cognitive and physical function for PLLA novice at walking with a prosthesis?

METHODS

People from inpatient prosthetic rehabilitation were recruited. Inclusion criteria were: age ≥ 50 years, unilateral transtibial amputation and able to walk independently. Gait velocity and the L Test under single-task (usual) and dual-task (walking while counting backwards) conditions assessed functional mobility. The Four Square Step Test (FSST) examined dynamic balance. The Montreal Cognitive Assessment (MoCA) and the Trail Making Test (TMT-B) assessed global cognitive status and executive function, respectively. Multivariable linear regressions evaluated the association of cognition on physical function.

RESULTS

Twenty-two people participated (age: 62.3 ± 8.9 years, male: 68.18%). The mean MoCA score was 26.23 ± 2.90. A 1-point MoCA increase was independently associated with faster gait velocity (cm/s) [single-task: 5.45 (95%CI: 2.35-8.54, AdjR² =0.46), dual-task: 5.04 (95%CI: 1.33-8.75, AdjR² =0.20) and a quicker L Test (s) [single-task: - 4.75 (95%CI: 7.22-2.28, AdjR² =0.45), dual-task: - 5.27 (95%CI: 8.74-1.80, AdjR² =0.38)]. A 1-second TMT-B increase was also independently associated with worse L Test performance [single-task: 0.21 s (95%CI: 0.03-0.39, AdjR² =0.20), dual-task: 0.29 s (95%CI: 0.06-0.51, AdjR² =0.30)]. No association was observed between MoCA or TMT-B on the FSST (p > 0.13).

SIGNIFICANCE

Better global cognitive function and executive function were independently associated with faster gait velocity and improved functional mobility, but not dynamic balance. The present study demonstrates a unique relationship between cognition and physical function that warrants further research on the cognitive demands among clinical tests of physical function in PLLA.

The effect of dual-task testing on the balance and gait of people with lower limb amputations: A systematic review

OBJECTIVE

To systematically review the literature on the effect of dual-task testing on the balance and gait of people with lower limb amputations (PLLA).

LITERATURE SURVEY

Databases MEDLINE, EMBASE, CINAHL, PsycINFO, Web of Science, and Scopus were searched in duplicate (inception to December 1, 2020).

METHODOLOGY

Inclusion criteria: participants were adults with transtibial, knee-disarticulation, transfemoral, or bilateral lower limb amputations; balance or gait was paired with a secondary task; and studies were peer-reviewed and published in English. Two authors independently reviewed articles and consensus was required. A standardized data extraction sheet was used to gather study relevant information in duplicate. Methodological quality of reporting was examined using the Downs and Black Scale. A meta-analysis was unable to be performed owing to substantial participant and protocol heterogeneity among the studies included.

SYNTHESIS

Of 3950 articles screened, 22 met inclusion criteria. Four assessed dual-task balance and 18 dual-task gait. During single-task standing, PLLA demonstrated higher sway distance and sway velocity than controls (CN); however, a greater dual-task effect was observed only for sway velocity. Gait pace, rhythm, variability, asymmetry, and postural control were observed to be worse in PLLA relative to CN during single-task. Dual-task gait testing resulted in a disproportionally reduced pace and rhythm and increased asymmetry in PLLA compared to CN.

CONCLUSIONS

People with lower limb amputations have impaired balance and gait, which is affected by dual-task to a greater degree compared to healthy adults. An examination of how PLLA-specific factors such as level of amputation, reason for amputation, and experience with a prosthesis affect dual-task performance has not yet been thoroughly explored. Future research should continue to characterize the cognitive-mobility link to better understand the challenges associated with the use of a prosthesis.

Use of Standardized Outcome Measures for People With Lower Limb Amputation: A Survey of Prosthetic Practitioners in the United States

OBJECTIVE

To assess the clinical resources available for the assessment of health outcomes in people with lower limb amputation and to understand barriers and facilitators associated with use of standardized outcome measures in clinical practice.

DESIGN

Cross-sectional survey.

SETTING

General community (online).

PARTICIPANTS

A volunteer sample of prosthetic practitioners was recruited through national professional organizations. Eligible participants were practitioners certified by a professional prosthetics organization and currently practicing as a prosthetist, prosthetist-orthotist, or prosthetic assistant.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

A custom-designed online survey on clinical use of patient-reported and performance-based standardized outcome measures to assess patients with lower limb amputation.

RESULTS

A total of 375 participants completed the survey. Most participants (79%) reported that they are encouraged or required to administer standardized outcome measures in their clinic or facility. Most participants reported that use of patient-reported and performance-based outcome measures are within their scope of practice (88%) and that they have the knowledge required for outcomes measurement (84%). Few participants agreed that outcomes measurement is standardized across the profession (30%). Most participants had access to small spaces and equipment for outcomes measurement, such as short hallways (65%-94%), stairs (69%), and tablets with wireless internet connection (83%). Most participants reported that they would be willing to spend between 5 (36% of participants) and 10 (43% of participants) minutes on self-reported surveys, and between 10 (41% of participants) and 20 (28% of participants) minutes on performance-based tests.

CONCLUSIONS

Outcomes measurement is encouraged or expected in contemporary prosthetic practice. Strategies to improve standardization and efficiency of administration are needed to facilitate routine use of outcome measures in clinical care.

Postamputation Cognitive Impairment Is Related to Worse Perceived Physical Function Among Middle-Aged and Older Prosthesis Users

OBJECTIVE

To compare characteristics between middle-aged and older prosthesis users with and without cognitive impairment and determine whether cognitive impairment contributes to variability in perceived physical function.

DESIGN

Cross-sectional, observational study SETTING: General community.

PARTICIPANTS

Adults 45 years or older, at least 1-year post lower limb amputation (LLA) who were walking independently with a prosthesis (N=119).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

We identified cognitive impairment using an education-adjusted Telephone Interview for Cognitive Status-modified score. Perceived physical function was measured using the Prosthesis Mobility Questionnaire.

RESULTS

Of 119 participants (mean age, 62.6±8.2 years; male: 89.1%; vascular etiology: 82.4%; years since amputation: 4.9±4.7 years), 28 (23.5%) had cognitive impairment. Compared with participants without cognitive impairment, those with cognitive impairment were more likely to use an assistive device (60.7% vs 25.3%, P=.002); were older (66.3±7.3 vs 61.5±8.1 years, P=.006) and had more chronic conditions (7.1±3.4 vs 5.4±2.5, P=.004), more depressive symptoms (6.6±5.1 vs 4.2±3.8, P=.008), and worse perceived physical function (2.0±0.6 vs 2.6±0.7, P<.001). Using backward stepwise linear regression, we found that participants with cognitive impairment had worse perceived physical function (standardized parameter estimate [β]=-0.15, P=.02), even after adjusting for depressive symptoms (β=-0.31, P<.001), prosthesis satisfaction (β=0.34, P<.001), number of chronic conditions (β=-0.19, P=.006), and assistive device use (βcane=0.01, P=.93; βother=-0.20, P=.003). Together, these variables explained 59% of perceived physical function variability.

CONCLUSIONS

Cognitive impairment is common and associated with worse perceived physical function post LLA, even after controlling for physical and mental health differences. Tailored rehabilitation interventions may be needed to improve perceived physical function in prosthesis users with cognitive impairment.

Clinical mobility metrics estimate and characterize physical activity following lower-limb amputation

Background

Regular physical activity following a lower-limb amputation is essential for maintaining health and a high quality of life. Most adults with a lower-limb amputation, however, participate in insufficient daily physical activity, and thus, are predisposed to poor health outcomes. Estimating physical activity after lower-limb amputation via common mobility metrics may aid in clinical decisions regarding treatment prioritization and prosthesis prescription. The objectives of this study were (a) to examine associations between daily physical activity and patient-reported and performance-based mobility metrics among adults with lower-limb amputation, and (b) to determine whether patient-reported and performance-based mobility metrics can distinguish between physical activity status [i.e., sedentary (< 5000 steps/day) or non-sedentary (≥ 5000 steps/day)] of adults with lower-limb amputation.

Methods

A cross-sectional study involving 35 adults with a unilateral transtibial (N = 23; 63.0 ± 10.4 years) or transfemoral amputation (N = 12; 58.8 ± 9.5 years) was conducted. Participants completed patient-reported (Prosthesis Evaluation Questionnaire-Mobility Subscale) and performance-based mobility metrics (L-Test, 10-m Walk Test, 6-min Walk Test). Physical activity, i.e., average steps/day, was measured with an accelerometer.

Results

Patient-reported and performance-based mobility metrics were associated with daily physical activity (p < 0.050). Prosthesis Evaluation Questionnaire-Mobility Subscale scores, L-Test time, 10-m Walk Test speed and 6-min Walk Test distance independently explained 11.3%, 31.8%, 37.6% and 30.7% of the total variance in physical activity. Receiver operating characteristic curves revealed patient-reported and performance-based mobility metrics significantly distinguish between physical activity status, i.e., sedentary (< 5000 steps/day) versus non-sedentary (≥ 5000 steps/day). Preliminary cut-points for mobility metrics to classify physical activity status were determined.

Conclusions

Following a lower-limb amputation, patient-reported and performance-based mobility metrics may estimate daily physical activity, thereby aiding clinical decisions regarding treatment prioritization as well as prosthesis selection.

Vibration Sensitivity Is Associated With Functional Balance After Unilateral Transtibial Amputation

Objectives

To evaluate differences in vibration perception thresholds between adults with transtibial amputation and age-matched adults without amputation and to examine associations between vibration perception thresholds and balance performance. We hypothesized that adults with transtibial amputation would demonstrate lower thresholds compared with adults without amputation and that lower thresholds would be associated with better functional balance.

Design

Prospective cross-sectional study.

Setting

National conference, clinical practice, and university laboratory.

Participants

Adults (N=34) with a nondysvascular, unilateral, transtibial amputation and 43 age-matched controls without amputation.

Interventions

Participants' vibration perception thresholds were evaluated bilaterally by applying a vibration stimulus to the midpatella and recording their verbal response to conscious perception of stimulus. Functional balance was assessed with the Berg Balance Scale and the Four Square Step Test.

Main Outcome Measures

Residual and sound limb (right and left for controls) vibration perception thresholds, Berg Balance Scale, and Four Square Step Test.

Results

For participants with transtibial amputation and controls, there were no significant between-group (P=.921) or interlimb (P=.540) differences in vibration perception thresholds. Overall, robust regression models explained 35.1% and 19.3% variance in Berg Balance Scale scores and Four Square Step Test times, respectively. Among adults with transtibial amputation, vibration perception thresholds were negatively associated with Berg Balance Scale scores (P=.009) and positively associated with Four Square Step Test times (P=.048). Among controls, average vibration perception thresholds were not significantly associated with functional balance (P>.050).

Conclusions

Adults with nondysvascular, transtibial-level amputation demonstrated similar vibration detection compared with adults with intact limbs, indicating that vibration detection is preserved in the amputated region postamputation. These findings suggest a unique relationship between vibration perception and functional balance post-transtibial amputation.

Use of a Single Wearable Sensor to Evaluate the Effects of Gait and Pelvis Asymmetries on the Components of the Timed Up and Go Test, in Persons with Unilateral Lower Limb Amputation

The Timed Up and Go (TUG) test quantifies physical mobility by measuring the total performance time. In this study, we quantified the single TUG subcomponents and, for the first time, explored the effects of gait cycle and pelvis asymmetries on them. Transfemoral (TF) and transtibial (TT) amputees were compared with a control group. A single wearable inertial sensor, applied to the back, captured kinematic data from the body and pelvis during the 10-m walk test and the TUG test. From these data, two categories of symmetry indexes (SI) were computed: One SI captured the differences between the antero-posterior accelerations of the two sides during the gait cycle, while another set of SI quantified the symmetry over the three-dimensional pelvis motions. Moreover, the total time of the TUG test, the time of each subcomponent, and the velocity of the turning subcomponents were measured. Only the TF amputees showed significant reductions in each SI category when compared to the controls. During the TUG test, the TF group showed a longer duration and velocity reduction mainly over the turning subtasks. However, for all the amputees there were significant correlations between the level of asymmetries and the velocity during the turning tasks. Overall, gait cycle and pelvis asymmetries had a specific detrimental effect on the turning performance instead of on linear walking.

Rasch validation and comparison of the German versions of the Locomotor Capabilities Index-5 and Prosthetic Mobility Questionnaire 2.0 in lower-limb prosthesis users

This study aimed to compare, through Rasch analysis, the psychometric properties of the Locomotor Capabilities Index (LCI-5) and Prosthetic Mobility Questionnaire (PMQ 2.0) in German lower-limb prosthesis users. The questionnaires were concurrently administered to a convenience sample of 98 consecutively recruited individuals with lower limb amputation (LLA) (male/female = 61/37; mean age 57 ± 14 years). LCI-5 showed disordered rating scale thresholds (one response option in three items required collapsing); local dependence between two items (resolved by creating a testlet); underfit of one item ('Get up from the floor'); and presence of a second weak dimension. PMQ 2.0 showed a correctly functioning rating scale; good fit of the data to the model (apart from some overfit); local dependence between two items (absorbed by creating a testlet); and essential unidimensionality. At scale co-calibration onto a common interval-scaled metric, PMQ 2.0 was better targeted than LCI-5 (i.e. the extent of item difficulty was more appropriate for the sample) and its operational range allowed a more precise measurement of higher locomotor abilities. The correlation between LCI-5 and PMQ 2.0 scores was rho =  0.78. In conclusion, LCI-5 revealed some drawbacks, confirming a previous Rasch study; refinement of its rating scale and item selection seems therefore warranted. The PMQ 2.0 demonstrated good overall measurement quality, in line with previous Italian and Slovene studies. The operational range of the PMQ 2.0 makes it more suitable than LCI-5 for assessing people with high locomotor abilities.

A new valid Walking Aid Scale better predicts distance walked by prosthesis users than Prosthetic Mobility Questionnaire 2.0 and Activities-Specific Balance Confidence Scale

The availability of psychometrically-sound and parsimonious outcome measures is key for optimizing decision-making about prosthetic fitting and rehabilitation in lower limb prosthesis users. Despite the increasing clinical use of observational and self-reported scales for assessing mobility and balance, there is currently no scale that accounts for the use of assistive devices while walking under conditions of increasing difficulty. Therefore, the purpose of this study was to develop and validate a Walking Aid Scale (WAS) in a cross-sectional sample of 144 prosthesis users. Specifically, we examined internal consistency and concurrent validity of WAS against two commonly used self-report measures of prosthetic mobility and balance confidence - the Prosthetic Mobility Questionnaire 2.0 (PMQ 2.0) and Activities-Specific Balance Confidence Scale (ABC-5). The predictive value of WAS, in comparison to PMQ 2.0 and ABC-5, was assessed using a 6-Minute Walk Test (6MWT) and participants' characteristics. The WAS showed significant moderate-to-good correlations with PMQ 2.0 and ABC-5, and all scales correlated well with age and 6MWT. Participants who relied less on walking aids reported higher mobility levels, greater balance confidence, and walked longer distances. Age was associated with greater use of walking aids and lower mobility and balance confidence. In the stepwise linear regression analysis, age, amputation level, time since amputation, and WAS predicted about two-thirds of the variability in 6MWT with no significant contribution of PMQ 2.0 and ABC-5. These findings indicate that WAS is a valid instrument and a better predictor of walking distance than PMQ 2.0 and ABC-5 in the lower limb prosthesis users.