Physical performance and self-report outcomes associated with use of passive, adaptive, and active prosthetic knees in persons with unilateral, transfemoral amputation: Randomized crossover trial

Abstract

Prosthetic knees are a vital component in an artificial limb. Contemporary knees include passive, (mechanical), adaptive (computerized), or active (motorized) control systems and have the potential to mitigate amputation-related functional impairments and activity limitations. A 14 mo randomized crossover trial was conducted. Participants (n = 12, mean age = 58 yr) were tested under three conditions: passive control (existing knee), adaptive control (Ossur Rheo Knee II), and active control (Ossur Power Knee II). Training and acclimation time were provided to participants in the adaptive and active knees. Outcome measures included indoor tests (Timed Up and Go test [TUG], stairs, and ramp), outdoor tests (walking course and perceived exertion), step activity monitor, self-report surveys (mobility, balance confidence, physical function, fatigue, and general health), and fall incidence. Mixed-effects linear regression modeling was used to evaluate data. Compared with passive control, adaptive control significantly improved comfortable TUG time (difference = 0.91 s, p = 0.001) and reported physical function (difference = 1.26 [T-score], p = 0.03). Active control significantly increased comfortable TUG, fast TUG, and ramp times (difference = 3.02, 2.66, and 0.96 s, respectively, all p < 0.03) and increased balance confidence (difference = 3.77, p = 0.003) compared with passive control. Findings suggest that adaptive knee control may enhance function compared with passive control but that active control can restrict mobility in middle-age or older users with transfemoral amputation.

Clinical trial registration: ClinicalTrials.gov; "Use of Passive, Adaptive, and Active Prosthetic Knees in Persons With Unilateral, Transfemoral Amputation": NCT02219230; https://clinicaltrials.gov/ct2/show/NCT02219230.

Keywords: adaptive control system; amputation; amputee; artificial limb; longitudinal studies; measurement; outcomes evaluation; physical performance testing; prosthetic knee; questionnaires.