Use of Passive, Adaptive, and Active Prosthetic Knees in Persons With Unilateral, Transfemoral Amputation

Outcomes Associated With Use of Passive, Adaptive, and Active Prosthetic Knees in Persons With Unilateral, Transfemoral Amputation: a Randomized Crossover Trial

The goals of this study are to assess measured, observed, and self-reported outcomes achieved through the use of passive (mechanical), active(motorized) and adaptive (magnetorheological) prosthetic knee control systems in individuals with unilateral, transfemoral amputation.

An interrupted time-series trial with pre/post baseline assessments, randomized crossover of interventions, and within-phase repeated measures is used to evaluate and compare the effectiveness of the Össur Power Knee II and the Össur Rheo Knee in individuals with unilateral, transfemoral amputation. A rigorous and clinically-meaningful experimental protocol is applied to verify study participants receive appropriate training, experience, and assessment in each knee condition. A suite of standardized and ad-hoc physical performance tests, patient-reported questionnaires, and monitoring technologies were carefully selected to assess important, clinically-relevant participant outcomes. Comparative effectiveness of three prosthetic knee interventions are evaluated using direct measurement (i.e., timed tests), observed clinical ratings (i.e., subjective assessments of gait quality) and self-report instruments (i.e., health status surveys). Analyses will focus on identifying differences between control system technologies inherent to each type of prosthetic knee (i.e., passive [mechanical], adaptive [magnetorheological], and active [power]). Outcomes will be used to establish recommendations for which activities and patients knees are most appropriate or likely to produce a desired effect.

Inclusion Criteria:

• age 45 - 75
• body weight less than 275lbs
• unilateral amputation between the hip and knee
• amputation due to non-vascular causes
• no other major limb amputations
• amputation occurred at least 2 years prior
• stable limb volume (i.e., at least 6 months on an unmodified prosthetic socket)
• intact skin tissue without open wounds or sores for at least 2 months
• physiologically stable medical condition (i.e., non-degenerative)
• possession and regular (i.e., daily) use of a prosthesis with a prosthetic knee with non-microprocessor (i.e., mechanical or fluid) stance control
• Medicare functional classification level (MFCL or "K-level") 3

Exclusion Criteria:

• expect to receive or are expected to require a replacement prosthetic socket within 15 months
• complete reliance on an assistive device (i.e., cane or walker) for ambulation