Early effects of a microprocessor-controlled knee joint on functional mobility and user satisfaction in veterans with limb loss

Objective: To evaluate the effects of a polycentric microprocessor-controlled knee joint on functional mobility and user satisfaction. Design: Before–after pilot trial. Setting: Tertiary-level physical therapy and rehabilitation hospital. Participants: Ten adults with unilateral transfemoral or through-knee amputations due to trauma. Intervention: Transition from various monocentric microprocessor-controlled knees to a polycentric microprocessor-controlled hydraulic knee. Main measures: Functional performance assessed using the Timed Up and Go, 6-Minute Walk Test, Hill Assessment Index, Stair Assessment Index, and user satisfaction measured by the Satisfaction with Prosthesis Questionnaire. Results: The Time Up and Go and 6-Minute Walk Test showed nonsignificant improvements with moderate effect sizes (Cohen's d = 0.43 and 0.58; p = .205 and .098, respectively). No significant change was observed in the Stair Assessment Index. A statistically significant improvement was found in the descend-specific Hill Assessment Index, accompanied by a significant reduction in task duration (r = 0.95; p = .034; Cohen's d = 0.85; p = .025, respectively). User satisfaction demonstrated a positive trend, with a moderate-to-large effect size (Cohen's d = 0.68; p = .059), although this did not reach statistical significance. Conclusions: Transitioning to the polycentric microprocessor-controlled knee joint may enhance incline-related mobility in active prosthesis users. The positive trend in user satisfaction suggests potential benefits; however, this requires confirmation in larger studies. Outcomes may be influenced by learning effects and socket comfort variability. These preliminary findings support the need for individualized prosthetic prescriptions and warrant larger, controlled trials with extended follow-up.