Effects of extended powered knee prosthesis stance time via visual feedback on gait symmetry of individuals with unilateral amputation: a preliminary study.

BACKGROUND: Establishing gait symmetry is a major aim of amputee rehabilitation and may be more attainable with powered prostheses. Though, based on previous work, we postulate that users transfer a previously-learned motor pattern across devices, limiting the functionality of more advanced prostheses. The objective of this study was to preliminarily investigate the effect of increased stance time via visual feedback on amputees' gait symmetry using powered and passive knee prostheses. METHODS: Five individuals with transfemoral amputation or knee disarticulation walked at their self-selected speed on a treadmill. Visual feedback was used to promote an increase in the amputated-limb stance time. Individuals were fit with a commercially-available powered prosthesis by a certified prosthetist and practiced walking during a prior visit. The same protocol was completed with a passive knee and powered knee prosthesis on separate days. We used repeated-measures, two-way ANOVA (alpha = 0.05) to test for significant effects of the feedback and device factors. Our main outcome measures were stance time asymmetry, peak anterior-posterior ground reaction forces, and peak anterior propulsion asymmetry. RESULTS: Increasing the amputated-limb stance time via visual feedback significantly improved the stance time symmetry (p = 0.012) and peak propulsion symmetry (p = 0.036) of individuals walking with both prostheses. With the powered knee prosthesis, the highest feedback target elicited 36% improvement in stance time symmetry, 22% increase in prosthesis-side peak propulsion, and 47% improvement in peak propulsion symmetry compared to a no feedback condition. The changes with feedback were not different with the passive prosthesis, and the main effects of device/ prosthesis type were not statistically different. However, subject by device interactions were significant, indicating individuals did not respond consistently with each device (e.g. prosthesis-side propulsion remained comparable to or was greater with the powered versus passive prosthesis for different subjects). Overall, prosthesis-side peak propulsion averaged across conditions was 31% greater with the powered prosthesis and peak propulsion asymmetry improved by 48% with the powered prosthesis. CONCLUSIONS: Increasing prosthesis-side stance time via visual feedback favorably improved individuals' temporal and propulsive symmetry. The powered prosthesis commonly enabled greater propulsion, but individuals adapted to each device with varying behavior, requiring further investigation.

Reliability, Validity, and Responsiveness of Clinical Performance-Based Outcome Measures of Walking for Individuals With Lower Limb Amputations: A Systematic Review.

Background: Clinical outcome measures are important to use for individuals with lower limb amputations (LLA) because such individuals require intensive functional gait training before and after being fitted with prostheses. Using standardized instruments throughout the episode of care allows clinicians to objectively monitor patient progress, make evidence-based decisions regarding the plan of care, and communicate results in meaningful ways to patients, payers, and other clinicians. Many clinical outcome measures exist, but not all have been validated and shown to be reliable within this population of interest. Purpose: The aim of this review was to provide a comprehensive overview of the psychometric properties of all current performance-based outcome measures applicable to individuals with lower limb amputations. Data Sources: Reviewers searched for articles using the online databases PubMed/MEDLINE and CINAHL. Reviewers also conducted a manual search of the reference list of 1 of the previously published systematic reviews to identify any additional studies not detected with the online database search. Study Selection: The 2 reviewers screened titles and abstracts for relevance. The same reviewers obtained and read full-text articles of the potentially relevant studies. Reviewers resolved any discrepancies of the inclusion assessment by further discussion. Data Extraction: The reviewers created tables to extract psychometric properties of interest from the included articles. Both reviewers extracted the data from the articles and placed relevant values into a table for each primary outcome measure identified. Data Synthesis: The rigor of study reporting was guided by use of the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Checklist. Each reviewer independently read and appraised the included articles, assigning a score to each checklist item. The sum of scores for each item was calculated to appraise the overall quality of reporting of the included articles. Limitations: Review-level limitations included the absence of a third reviewer to settle any disagreements on article inclusion and article appraisal. Additionally, the percentage of reviewer agreement on article appraisal was not determined before disagreements about checklist item satisfaction were resolved. Furthermore, reviewers only extracted data on reliability, validity, and responsiveness; instrument characteristics, such as floor and ceiling effects, are also important. Conclusions: Valid and reliable performance-based clinical measures of ambulation in individuals with LLA were identified. Further research should investigate the minimally clinical, important difference of these clinical measures and address trends in unmet reporting guidelines.