Construct Validity of the Prosthetic Limb Users Survey of Mobility (PLUS-M) in Adults With Lower Limb Amputation

Assessing mobility for persons with lower limb amputation: the Figure-of-Eight Walk Test with the inclusion of two novel conditions

PURPOSE

To investigate the internal consistency, convergent and known-groups construct validity of the Figure-of-Eight Walk Test with two novel conditions in persons with lower limb amputation, and to examine differences in walking performance between the three conditions within a group of persons with transtibial amputation and transfemoral amputation/knee disarticulation.

MATERIALS AND METHODS

Fifty adults with unilateral amputation participated, 28 of whom had undergone a transtibial amputation and 22 a transfemoral amputation/knee disarticulation. Three Figure-of-Eight Walk Test conditions were investigated: 1) walking at a self-selected walking speed, 2) walking while carrying a tray with two cups of water, and 3) walking on uneven terrain. Internal consistency was evaluated using Cronbach's alpha. Convergent construct validity was examined by analysing the relationship between the Figure-of-Eight Walk Test parameters and performance-based parameters (Amputee Mobility Predictor, Ten-Meter Walk Test, Six-Minute Walk Test) and self-report measures (Prosthetic Limb Users Survey of Mobility, Activities-specific Balance Confidence Scale) using Spearman's rank-order correlations. Known-groups construct validity was assessed by comparing the Figure-of-Eight Walk Test parameters based on anatomical level of amputation. Friedman's test and post hoc analysis were used to examine differences between the walking conditions within each group.

RESULTS

Cronbach's alpha coefficients of the Figure-of-Eight Walk Test parameters for all three conditions ranged from 0.89 to 0.99. The Figure-of-Eight Walk Test time and step parameters demonstrated moderate to good correlation (ρ = -0.50 to -0.77) for performance-based mobility measures. The correlations were stronger during Condition 3 in comparison with the original Figure-of-Eight Walk Test. The correlation was fair to good (ρ = -0.41 to -0.57) for the self-report mobility measures. Comparison between groups showed a difference between transtibial and transfemoral amputation/knee disarticulation participants when it comes to the Figure-of-Eight Walk Test time and smoothness parameters in Condition 2 (p < 0.05). Comparison between walking conditions within each group showed significant differences in the Figure-of-Eight Walk Test parameters in the two novel conditions in comparison with the original Figure-of-Eight Walk Test. The Figure-of-Eight Walk Test and the novel conditions demonstrated excellent internal consistency, good convergent construct validity, and evidence of known-groups construct validity. Future studies should further develop and standardise the smoothness scale to better quantify walking performance and assess the responsiveness and reliability (inter-rater and intra-rater) of the Figure-of-Eight Walk Test (time and steps) and the novel conditions, while studies on known-groups validity should include persons with a wider mobility range.IMPLICATIONS FOR REHABILITATIONFigure-of-Eight Walk Test with the two novel conditions, which include carrying a load and walking on uneven terrain, may help to provide meaningful information about walking ability in daily life.The two novel conditions pose different challenges to persons with lower limb amputation when compared to the original Figure-of-Eight Walk Test and underscore the relevance to assess mobility under challenging walking conditions.The Figure-of-Eight Walk Test and the two novel conditions demonstrated excellent internal consistency, good convergent construct validity, and evidence of known-groups construct validity.

The minimal clinically-important difference of the Prosthesis Evaluation Questionnaire - Mobility Scale in subjects undergoing lower limb prosthetic rehabilitation training

BACKGROUND

There is increasing interest in psychometrically sound outcome measures of mobility for people with lower limb amputation (LLA), in order to accurately monitor the impact of the prosthetic training during and after rehabilitation.

AIM

To determine the minimum detectable change (MDC) and minimal clinically important difference (MCID) for the Prosthesis Evaluation Questionnaire-Mobility Scale (PEQ-MS) in people with LLA.

DESIGN

Prospective single-group observational study.

SETTING

Two free-standing Rehabilitation Hospitals.

POPULATION

Eighty-seven adult inpatients with LLA undergoing prosthetic rehabilitation.

METHODS

Patients completed the self-report PEQ-MS twice, immediately before and after prosthetic rehabilitation training. We administered a 7-point Global Rating of Change scale at the end of training as external anchor, to quantify the effect (improvement/deterioration) of the intervention.

RESULTS

Test-retest reliability of the PEQ-MS (N.=24) was high (ICC2,1=0.90). The MDC at the 95% confidence level was 5.5 points. This value, together with those of the mean-change approach and receiver-operating characteristic-curve analysis (AUC>0.89), suggested the selection of a MCID for PEQ-MS of eight points of change, i.e. 16.7% of the maximum possible score (95% CI: 6.5-9.5).

CONCLUSIONS

The PEQ-MS showed a high ability to detect change over time (responsiveness).The above MCID value - derived from a triangulation of distribution (MDC) and anchor-based methods - represents a minimal level of change (perceived as important by the patient) in mobility of people with LLA undergoing prosthetic rehabilitation training.

CLINICAL REHABILITATION IMPACT

The PEQ-MS is a widely used and analyzed outcome measure. The present study calculated - in a sample of people with LLA undergoing prosthetic training - both the MDC and MCID of the PEQ-MS, showing the high responsiveness of this tool. These values increase confidence in interpreting change in PEQ-MS values, and can help in clinical decision making.

Variables that Influence Basic Prosthetic Mobility in People With Non-Vascular Lower Limb Amputation

BACKGROUND

There exists a dearth of evidence on rehabilitation factors that influence prosthetic mobility in people with lower limb amputation (LLA). Examining variables that contribute to prosthetic mobility can inform rehabilitation interventions, providing guidance in developing more comprehensive care for these individuals.

OBJECTIVE

To determine the influence of modifiable and non-modifiable variables related to LLA and their impact on prosthetic mobility, using the International Classification of Functioning, Disability and Health (ICF) model. Secondarily, to determine if personal factors and self-reported balance and mobility are predictive of Component timed-up-and-go (cTUG) performance.

DESIGN

Cross-sectional study of a convenience sample.

SETTING

National conference.

PARTICIPANTS

People (N=68) with non-vascular causes of unilateral LLA.

METHODS

Assessment of anthropometrics, mobility, bilateral hip extensor strength, hip range of motion, single limb balance, and self report measures. Lasso linear regression and extreme gradient boosting analyses were used to determine influence of variables on prosthetic mobility.

MAIN OUTCOME MEASURE

Timed performance of the cTUG.

RESULTS

The following five variables were found to influence basic prosthetic mobility (P ≤ .05) in people with transtibial amputation: hip extensor strength, hip range of motion, single limb balance, waist circumference, and age. In the transfemoral cohort, number of comorbidities and waist circumference primarily influenced prosthetic mobility. Additionally, 66% of the variance in cTUG total time for the entire sample could be explained by simply regressing on level of amputation, number of comorbidities, age and Activities-specific Balance Confidence scale score, all variables easily collected in a waiting room.

CONCLUSION

Variables that are modifiable with physical therapy intervention including hip extensor strength, hip range of motion, single limb balance, and waist circumference significantly influenced basic prosthetic mobility. These variables can be affected by targeted rehabilitation interventions and lifestyle changes.

LEVEL OF EVIDENCE

II.

Mobility analysis of AmpuTees (MAAT 5): Impact of five common prosthetic ankle-foot categories for individuals with diabetic/dysvascular amputation

Introduction

Diabetes and vascular disease represent the most common etiologies for lower limb amputations. In lower limb loss rehabilitation, the prosthetic ankle-foot mechanism is the most common major component needed to restore function. The purpose of this study was to examine the impact of five common prosthetic ankle-foot mechanisms on functional mobility in a large sample of individuals with amputation due to diabetes/dysvascular disease.

Methods

A retrospective analysis of the Prosthetic Limb Users' Survey of Mobility (PLUS-M®) captured in the patient care setting. A total of 738 individuals were included and subsequently subdivided into five groups based on the ankle-foot mechanism of their current prosthesis. Groups were compared using a general linear univariate model with age, body mass index, comorbid health status, time since amputation, and amputation level entered as covariates.

Results

The microprocessor ankle-foot group had the highest mobility (F_4,728 = 3.845, p=0.004), which was followed by the vertical loading pylon type ankle-foot, the hydraulic ankle-foot, the flex-walk-type ankle-foot, and lastly the flex-foot-type ankle-foot.

Conclusion

These results demonstrate that the selection of different prosthetic ankle-foot technology directly impacts functional mobility for the patient with an amputation due to diabetes and/or vascular disease.

Using Clinical Balance Tests to Assess Fall Risk among Established Unilateral Lower Limb Prosthesis Users: Cutoff Scores and Associated Validity Indices

BACKGROUND

Clinicians are routinely required to make decisions about fall risk among lower limb prosthesis (LLP) users. These decisions can be guided by standardized clinical balance tests but require population- and test-specific cutoff scores and validity indices to categorize individuals as probable fallers or nonfallers on the basis of test performance. Despite the importance of cutoff scores and validity indices to clinical interpretation of clinical balance test scores, they are rarely reported for LLP users. In their absence, clinicians cannot use results from clinical balance tests to assess the likelihood of a fall by any one patient.

OBJECTIVE

Derive cutoff scores, and associated validity indices, for clinical balance tests administered to established unilateral LLP users.

DESIGN

Cross-sectional study.

SETTING

Outpatient clinic and research laboratory.

PARTICIPANTS

Established ambulatory unilateral transtibial and transfemoral prosthesis users (n = 40).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURE(S)

Optimal cutoff scores and related validity indices (ie, area under the curve, sensitivity, specificity, likelihood ratios) were computed for five balance tests, the activities-specific balance confidence scale (ABC), timed up and go (TUG), four square step test (FSST), Berg balance scale (BBS), and narrowing-beam walking test (NBWT).

RESULTS

Cutoff scores were identified for the NBWT (≤.43/1.0), TUG (≥8.17 seconds], FSST (≥8.49 seconds), BBS (≤50.5/56), and ABC (≤80.2/100). Validity indices (ie, area under the curve, sensitivity, specificity, and likelihood ratios) for the NBWT, TUG, and FSST had greater diagnostic accuracy and provided more information about the probability of a fall than those for the BBS or ABC.

CONCLUSION

Performance above or below identified cutoff scores for the NBWT, FSST, and TUG provides information about potentially important shifts in the probability of falling among established unilateral LLP users. These results can serve as initial benchmarks to reduce uncertainty surrounding fall risk assessment in established unilateral LLP users but require future prospective evaluation.

LEVEL OF EVIDENCE

III.

Psychometric Properties of Functional, Ambulatory, and Quality of Life Instruments in Lower Limb Amputees: A Systematic Review

OBJECTIVE

Summarize the psychometric properties of functional, ambulatory, and quality of life instruments among adult lower limb amputees, highlighting evidence deemed generalizable to the United States Medicare population.

DATA SOURCES

Six databases and existing systematic reviews through October 30, 2017. Searches included terms for lower limb amputation or prostheses and outcome measures in humans, without language restriction.

STUDY SELECTION

We included peer-reviewed studies of at least 20 adults (≥18 years) with lower limb amputation. Eligible studies reported on psychometric properties of functional, ambulatory, or quality of life instruments. Fifty-three of 425 retrieved articles (12%) met criteria.

DATA EXTRACTION

Study characteristics and psychometric property data (validity, reliability, responsiveness, minimum detectable change, minimal important difference, or floor or ceiling effect) were extracted into a customized form based on standardized criteria. All extracted data were confirmed by 2 experts in systematic review and rehabilitation outcome measurement. Instruments were categorized regarding having been validated and found reliable. Other reported psychometric properties were recorded. Studies were also assessed for applicability to the Medicare population based on age and amputation etiology (dysvascular).

DATA SYNTHESIS

Fifty-six studies (in 53 articles) reported psychometric properties of 50 instruments. There is evidence for both validity and reliability for 30 instruments, 17 of which have evidence that was deemed generalizable to the Medicare population. Most of the remaining instruments have evidence of either validity or reliability, but not both. Twelve instruments have been assessed specifically among lower limb amputees prior to prosthesis prescription. Thirteen instruments have been assessed regarding their predictive properties for future outcomes.

CONCLUSIONS

Numerous instruments assessing ambulation, function, quality of life, and other patient-centered outcomes have evidence of validity and reliability for adults with lower limb amputations. Researchers and clinicians should use validated, reliable instruments when feasible. Many existing and new instruments require validation for use with lower limb amputees.

Test-retest reliability of the special interest group on amputation medicine/Dutch working group on amputations and prosthetics mobility scale, in persons wearing a prosthesis after a lower-limb amputation

Purpose: To assess the test-retest reliability of the Special Interest Group on Amputation Medicine Mobility Scale/Dutch Working Group on Amputations and Prosthetics, better known as SIGAM/WAP mobility scale, in persons with a lower-limb amputation.Method: Longitudinal study at the outpatient departments of a rehabilitation center and a university medical center. Persons with a lower-limb amputation, wearing a prosthesis, were assessed at the end of their multidisciplinary rehabilitation treatment twice, with a 3-week interval, by the same practitioner. Test-retest reliability was quantified using the intraclass correlation coefficient for agreement.Results: Eighty persons participated (mean age ± SD, 61 ± 15 years; 61% men; 76% vascular cause of amputation; 70% able to walk >50m). Fifty-one of them rated themselves to be stable with respect to their mobility and their intraclass correlation coefficient was 0.90 (95% confidence intervals 0.84-0.94).Conclusions: The Special Interest Group on Amputation Medicine Mobility Scale/Dutch Working Group on Amputations and Prosthetics had, at the outpatient departments of a rehabilitation center and a university medical center, excellent test-retest reliability in persons wearing a prosthesis after a lower-limb amputation.Implications for rehabilitationThe Special Interest Group on Amputation Medicine/Dutch Working Group on Amputations and Prosthetics Mobility Scale was developed to classify mobility after a lower-limb amputation and wearing a prosthesis.The Dutch translation of this mobility scale has excellent test-retest reliability.

Mobility Analysis of AmpuTees (MAAT 4): classification tree analysis for probability of lower limb prosthesis user functional potential

Purpose: To develop a predictive model to inform the probability of lower limb prosthesis users' functional potential for ambulation.Materials and Methods: A retrospective analysis of a database of outcomes for 2770 lower limb prosthesis users was used to inform a classification and regression tree analysis. Gender, age, height, weight, body mass index adjusted for amputation, amputation level, cause of amputation, comorbid health status and functional mobility score [Prosthetic Limb Users Survey of Mobility (PLUS-M™)] were entered as potential predictive variables. Patient K-Level was used to assign dependent variable status as unlimited community ambulator (i.e., K3 or K4) or limited community/household ambulator (i.e., K1 or K2). The classification tree was initially trained from 20% of the sample and subsequently tested with the remaining sample.Results: A classification tree was successfully developed, able to accurately classify 87.4% of individuals within the model's training group (standard error 1.4%), and 81.6% within the model's testing group (standard error 0.82%). Age, PLUS-M™ T-score, cause of amputation and body weight were retained within the tree logic.Conclusions: The resultant classification tree has the ability to provide members of the clinical care team with predictive probabilities of a patient's functional potential to help assist care decisions.Implications for RehabilitationClassification and regression tree analysis is a simple analytical tool that can be used to provide simple predictive models for patients with a lower limb prosthesis.The resultant classification tree had an 81.6% (standard error 0.82%) accuracy predicting functional potential as an unlimited community ambulator (i.e., K3 or K4) or limited community/ household ambulator (i.e., K1 or K2) in an unknown group of 2770 lower limb prosthesis users.The resultant classification tree can assist with the rehabilitation team's care planning providing probabilities of functional potential for the lower limb prosthesis user.

Mobility Analysis of AmpuTees (MAAT I): Quality of life and satisfaction are strongly related to mobility for patients with a lower limb prosthesis

BACKGROUND

While rehabilitation professionals are historically trained to place emphasis on the restoration of mobility following lower limb amputation, changes in healthcare dynamics are placing an increased emphasis on the limb loss patient's quality of life and general satisfaction. Thus, the relationship between these constructs and mobility in the patient with lower limb loss warrants further investigation.

OBJECTIVES

To determine the relationship between mobility of the patient with lower limb loss and both (1) general satisfaction and (2) quality of life.

STUDY DESIGN

Retrospective chart analysis.

METHODS

A retrospective chart review of the Prosthetic Limb Users Survey of Mobility and the Prosthesis Evaluation Questionnaire-Well-Being subsection. Pearson correlations were used to test relationships.

RESULTS

Data from 509 patients with a lower limb prosthesis were included. Mobility was found to be positively correlated with quality of life ( r = 0.511, p < 0.001, 95% confidence interval (0.443, 0.569)) and general satisfaction ( r = 0.475, p < 0.001, 95% confidence interval (0.403, 0.542)), as well as their arithmetic mean (i.e. Prosthesis Evaluation Questionnaire-Well-Being) ( r = 0.533, p < 0.001, 95% confidence interval (0.466, 0.592)).

CONCLUSION

This study provides evidence of a strong positive correlation between mobility and both quality of life and general satisfaction. Thus, in the holistic care of a patient with lower limb loss, maximizing mobility would correlate with greater quality of life and general satisfaction. Clinical relevance There is growing emphasis on the quality of life and general satisfaction experienced by patients undergoing prosthetic rehabilitation. The results of this study underscore the importance of providing prosthetic rehabilitation that maximizes the patient's mobility, noting that these individuals also report greater quality of life and general satisfaction.

Bimodal ankle-foot prosthesis for enhanced standing stability

Previous work suggests that to restore postural stability for individuals with lower-limb amputation, ankle-foot prostheses should be designed with a flat effective rocker shape for standing. However, most commercially available ankle-foot prostheses are designed with a curved effective rocker shape for walking. To address the demands of both standing and walking, we designed a novel bimodal ankle-foot prosthesis that can accommodate both functional modes using a rigid foot plate and an ankle that can lock and unlock. The primary objective of this study was to determine if the bimodal ankle-foot system could improve various aspects of standing balance (static, dynamic, and functional) and mobility in a group of Veterans with lower-limb amputation (n = 18). Standing balance was assessed while subjects completed a series of tests on a NeuroCom Clinical Research System (NeuroCom, a Division of Natus, Clackamas, OR), including a Sensory Organization Test, a Limits of Stability Test, and a modified Motor Control Test. Few statistically significant differences were observed between the locked and unlocked ankle conditions while subjects completed these tests. However, in the absence of visual feedback, the locked bimodal ankle appeared to improve static balance in a group of experienced lower-limb prosthesis users whose PLUS-M mobility rating was higher than approximately 73% of the sample population used to develop the PLUS-M survey. Given the statistically significant increase in mean equilibrium scores between the unlocked and locked conditions (p = 0.004), future testing of this system should focus on new amputees and lower mobility users (e.g., Medicare Functional Classification Level K1 and K2 prosthesis users). Furthermore, commercial implementation of the bimodal ankle-foot system should include a robust control system that can automatically switch between modes based on the user's activity.

Test-Retest Reliability of Dynamic Balance Performance-Based Measures Among Adults With a Unilateral Lower-Limb Amputation

BACKGROUND

There is large variation in administration of performance-based, dynamic balance measures among adults with lower-limb amputation (LLA). Further, there has been limited exploration of test-retest reliability of these measures in adults with lower-limb loss, including whether there is a difference in reliability if one records "best" vs "average" performance across trials.

OBJECTIVE

To determine test-retest reliability of several balance tests for both "best" and "average" score performance in community-dwelling adults with a unilateral LLA, including quantification of the precision of individual scores (SE of the measurement, SEM) and estimates of minimal detectable change (MDC₉₀ ).

DESIGN

Cross-sectional study.

SETTING

Mobile research laboratory.

PARTICIPANTS

27 participants (55.5% female) with an average age of 51 (SD = 12.2) years, who were predominantly community-ambulators (92.5%), after a unilateral transtibial (n = 20), transfemoral (n = 5), or other major lower-extremity (n = 2) amputation, were included. Median time since amputation was 6.3 (2.3, 19 [25th, 75th interquartile range]) years.

METHODS

Reliability was evaluated using intraclass correlation coefficient (ICC) models (3,1 or 3,k). SEMs and MDC₉₀ values with 95% confidence intervals (CIs) were calculated.

MAIN OUTCOME MEASURES

360^o Turn Test, 5 Times Sit-To-Stand, Functional Reach Test, Figure-of-8 Walk Test, and Four Square Step Test (FSST).

RESULTS

The ICCs (3,1 or 3,k) for all tests (for both "best" and "average" performance) were considered good-to-excellent and CIs varied from 0.69 (95% CI = 0.40-0.85) to 0.97 (95% CI = 0.95-0.99). For most tests, "best" and "average" performance demonstrated similar ICC values. MDC₉₀ values did not surpass 10% of test means for any of the measures.

CONCLUSIONS

The dynamic balance measures evaluated for use among community-dwelling adults with a unilateral LLA demonstrated excellent reliability, along with high precision of scores and MDC values that did not exceed 10% of testing means. Either best or average scoring may be used when administering the majority of these tests, as long as the assessment method is appropriately documented and replicated at follow-up to allow direct comparisons. With the FSST, clinicians should consider taking the average of two FSST trials.

LEVEL OF EVIDENCE

III.

Differences in Physical Performance Measures Among Patients With Unilateral Lower-Limb Amputations Classified as Functional Level K3 Versus K4

OBJECTIVE

To determine whether differences in physical function, assessed via self-report questionnaires and physical performance tests, exist between individuals with lower-limb loss using a prosthetic device classified as a K3 versus a K4 functional level.

DESIGN

Cross-sectional study.

SETTING

A university physical therapy amputee clinic.

PARTICIPANTS

Participants (N=55) were included if they (1) were aged ≥18 years with a unilateral transfemoral or transtibial amputation; (2) were classified as K3 or K4 functional level; (3) completed all relevant outcome measures; and (4) were currently using a prosthesis.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Locomotor Capabilities Index (LCI), Prosthetic Evaluation Questionnaire-Mobility Section (PEQ-MS), Timed Up and Go (TUG), 10-Meter Walk Test (10MWT), Amputee Mobility Predictor (AMPPRO), and 6-Minute Walk Test (6MWT). K level was determined by group consensus based on a standardized clinical evaluation.

RESULTS

After controlling for covariates, patients classified as K3 had slower TUG times (P=.002) and self-selected and fast gait speeds (P<.001), lower AMPPRO scores (P<.001), and walked shorter distances during the 6MWT (P=.003) when compared with patients classified as K4. No significant between-group differences for the LCI or PEQ-MS were found.

CONCLUSIONS

Clinicians involved in prosthetic prescription may consider including the TUG, 10MWT, AMPPRO, and 6MWT during their clinical evaluations to help differentiate between individuals of higher functional mobility. The LCI and PEQ-MS may be less useful in classifying individuals as K3 versus K4 because of a ceiling effect.

Narrowing beam-walking is a clinically feasible approach for assessing balance ability in lower-limb prosthesis users

OBJECTIVE

Challenging clinical balance tests are needed to expose balance deficits in lower-limb prost-hesis users. This study examined whether narrowing beam-walking could overcome conceptual and practical limitations identified in fixed-width beam-walking.

DESIGN

Cross-sectional.

PARTICIPANTS

Unilateral lower-limb prosthesis users.

METHODS

Participants walked 10 times along a low, narrowing beam. Performance was quantified using the normalized distance walked. Heuristic rules were applied to determine whether the narrowing beam task was "too easy," "too hard," or "appropriately challenging" for each participant. Linear regression and Bland-Altman plots were used to determine whether combinations of the first 5 trials could predict participants' stable beam-walking performance.

RESULTS

Forty unilateral lower-limb prosthesis users participated. Narrowing beam-walking was appropriately challenging for 98% of participants. Performance stabilized for 93% of participants within 5 trials, while 62% were stable across all trials. The mean of trials 3-5 accurately predicted stable performance.

CONCLUSION

A clinical narrowing beam-walking test is likely to challenge a range of lower-limb prosthesis users, have minimal administrative burden, and exhibit no floor or ceiling effects. Narrowing beam-walking is therefore a clinically viable method to evaluate lower-limb prosthesis users' balance ability, but requires psychometric testing before it is used to assess fall risk.

Mobility Analysis of AmpuTees II: Comorbidities and Mobility in Lower Limb Prosthesis Users

Supplemental digital content is available in the text.

Objective

The aim of the study was to determine the impact of comorbidities on mobility in patients with lower limb prostheses.

Design

Cohort database chart review was conducted to examine mobility in lower limb prosthesis users grouped according to comorbidities. Regression models were used to determine significant predictor comorbidities for mobility. General linear univariate models were implemented to investigate differences in mobility among cohorts (N = 596).

Results

Patient age and history of stroke, peripheral vascular disease, and anxiety/panic disorders were predictors of decreased mobility. After adjusting for covariates, the differences in mobility reported by patients older than 65 yrs was compared with those younger than 65 yrs; in addition, we compared those with a history of peripheral vascular disease with those without. The comparative analyses for both categories did not satisfy the minimal clinically important difference. There were no significant differences when comparing overall comorbid health after adjusting for covariates.

Conclusions

Clinicians should consider patient age and history of stroke, peripheral vascular disease, or anxiety/panic disorders when optimizing a lower limb prosthesis users' mobility because these variables may be predictive of modest but clinically meaningful decreased prosthetic mobility. By contrast, common comorbid health conditions such as arthritis, chronic obstructive pulmonary disease, congestive heart failure, and diabetes do not seem predictive of decreased mobility among lower limb prosthesis users.

Laboratory- and community-based health outcomes in people with transtibial amputation using crossover and energy-storing prosthetic feet: A randomized crossover trial

Contemporary prosthetic feet are generally optimized for either daily or high-level activities. Prosthesis users, therefore, often require multiple prostheses to participate in activities that span a range of mobility. Crossover feet (XF) are designed to increase the range of activities that can be performed with a single prosthesis. However, little evidence exists to guide clinical prescription of XF relative to traditional energy storing feet (ESF). The objective of this study was to assess the effects of XF and ESF on health outcomes in people with transtibial amputation. A randomized crossover study was conducted to assess changes in laboratory-based (endurance, perceived exertion, walking performance) and community-based (step activity and self-reported mobility, fatigue, balance confidence, activity restrictions, and satisfaction) outcomes. Twenty-seven participants were fit with XF and ESF prostheses with standardized sockets, interfaces, and suspensions. Participants were not blinded to the intervention, and wore each prosthesis for one month while their steps were counted with an activity monitor. After each accommodation period, participants returned for data collection. Endurance and perceived exertion were measured with the Six-Minute Walk Test and Borg-CR100, respectively. Walking performance was measured using an electronic walkway. Self-reported mobility, fatigue, balance confidence, activity restrictions, and satisfaction were measured with survey instruments. Participants also reported foot preferences upon conclusion of the study. Differences between feet were assessed with a crossover analysis. While using XF, users experienced improvements in most community-based outcomes, including mobility (p = .001), fatigue (p = .001), balance confidence (p = .005), activity restrictions (p = .002), and functional satisfaction (p < .001). Participants also exhibited longer sound side steps in XF compared to ESF (p < .001). Most participants (89%) reported an overall preference for XF; others (11%) reported no preference. Results indicate that XF may be a promising alternative to ESF for people with transtibial amputation who engage in a range of mobility activities.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02440711.

Patient-Reported Outcomes Measurement Information System and Legacy Patient-Reported Outcome Measures in the Field of Orthopaedics: A Systematic Review

PURPOSE

To compare Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF) with legacy patient-reported outcome measures with regard to correlations, ease of use, and quality criteria for orthopaedic conditions.

METHODS

A systematic search of the PubMed/MEDLINE database was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify published articles that referenced the various PROMIS PF measures. Three authors independently reviewed selected studies. The search returned 130 studies, 44 of which underwent review. Of these, 18 were selected for inclusion. A general linear model and paired t-tests were used to assess for differences between legacy patient-reported outcome measures and PROMIS.

RESULTS

The combined sample size of all articles yielded 3,047 total patients. Overall, PROMIS PF measures and legacy scores showed strong correlations (range: 0.59-0.83) when evaluating upper extremity, lower extremity, and spine patients. PROMIS questionnaires (6.04, standard error [SE] = 0.7) have significantly fewer questions than legacy forms (24.27, SE = 4.36). In lower extremity studies, the PROMIS PF (100.14 seconds, SE = 28.41) forms were completed in significantly less time (P = .03) than legacy forms (243.70 seconds, SE = 45.8). No significant difference was found between the reliabilities of the 2 types of measures.

CONCLUSIONS

PROMIS PF scores correlate strongly, particularly in lower extremity patients, with some of the most commonly used legacy measures in orthopaedics. PROMIS can be administered quicker and applied to a broader patient population while remaining highly reliable.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV evidence.

A study to assess whether fixed-width beam walking provides sufficient challenge to assess balance ability across lower limb prosthesis users

OBJECTIVE

To evaluate the feasibility of fixed-width beam walking for assessing balance in lower limb prosthesis users.

DESIGN

Cross-sectional.

SETTING

Laboratory.

SUBJECTS

Lower limb prosthesis users.

METHODS

Participants attempted 10 walking trials on three fixed-width beams (18.6, 8.60, and 4.01 wide; 5.5 m long; 3.8 cm high).

MAIN MEASURES

Beam-walking performance was quantified using the distance walked to balance failure. Heuristic rules applied to each participant's beam-walking distance to classify each beam as "too easy," "too hard," or "appropriately challenging" and determine whether any single beam provided an appropriate challenge to all participants. The number of trials needed to achieve stable beam-walking performance was quantified for appropriately challenging beams by identifying the last inflection point in the slope of each participant's trial-by-trial cumulative performance record.

RESULTS

In all, 30 unilateral lower limb prosthesis users participated in the study. Each of the fixed-width beams was either too easy or too hard for at least 33% of the sample. Thus, no single beam was appropriately challenging for all participants. Beam-walking performance was stable by trial 8 for all participants and by trial 6 for 90% of participants. There was no significant difference in the number of trials needed to achieve stable performance among beams ( P = 0.74).

CONCLUSION

Results suggest that a clinical beam-walking test would require multiple beams to evaluate balance across a range of lower limb prosthesis users, emphasizing the need for adaptive or progressively challenging balance tests. While the administrative burden of a multiple-beam balance test may limit clinical feasibility, alternatives to ease this administrative burden are proposed.

The Component Timed-Up-and-Go test: the utility and psychometric properties of using a mobile application to determine prosthetic mobility in people with lower limb amputations

OBJECTIVE

Using a custom mobile application to evaluate the reliability and validity of the Component Timed-Up-and-Go test to assess prosthetic mobility in people with lower limb amputation.

DESIGN

Cross-sectional design.

SETTING

National conference for people with limb loss.

SUBJECTS

A total of 118 people with non-vascular cause of lower limb amputation participated. Subjects had a mean age of 48 (±13.7) years and were an average of 10 years post amputation. Of them, 54% ( n = 64) of subjects were male.

INTERVENTION

None.

MAIN MEASURE

The Component Timed-Up-and-Go was administered using a mobile iPad application, generating a total time to complete the test and five component times capturing each subtask (sit to stand transitions, linear gait, turning) of the standard timed-up-and-go test. The outcome underwent test-retest reliability using intraclass correlation coefficients (ICCs) and convergent validity analyses through correlation with self-report measures of balance and mobility.

RESULTS

The Component Timed-Up-and-Go exhibited excellent test-retest reliability with ICCs ranging from .98 to .86 for total and component times. Evidence of discriminative validity resulted from significant differences in mean total times between people with transtibial (10.1 (SD: ±2.3)) and transfemoral (12.76 (SD: ±5.1) amputation, as well as significant differences in all five component times ( P < .05). Convergent validity of the Component Timed-Up-and-Go was demonstrated through moderate correlations with the PLUS-M ( r_s = -.56).

CONCLUSION

The Component Timed-Up-and-Go is a reliable and valid clinical tool for detailed assessment of prosthetic mobility in people with non-vascular lower limb amputation. The iPad application provided a means to easily record data, contributing to clinical utility.