The effects of microprocessor prosthetic knee use in early rehabilitation: A pilot randomized controlled trial

Microprocessor-controlled prosthetic knees (MPKs) improve safety, stability, and mobility for people with transfemoral amputation. Despite these benefits, MPKs are often not used for people in early rehabilitation.

To assess the feasibility of a study that compares MPKs and nonmicroprocessor knees (NMPKs) for people with recent transfemoral amputation and report on health outcomes after 3 months of use. Investigators hypothesized that MPK users would have better outcomes than NMPK users.

Pilot randomized controlled study.

Institutional laboratory.

Adults with recent unilateral transfemoral amputation, deemed ready for their first prosthesis, and weighed <125 kg. Eighteen participants enrolled; 15 completed the study.

Participants were randomized to use a MPK or NMPK in their first prosthesis.

Feasibility outcomes included recruitment, retention, and missing data. Health outcome measures included performance-based and self-reported measures of mobility, participation, step activity, and falls.

Eighteen of 24 planned participants enrolled in the study. Fifteen participants received a study prosthesis and completed the 3-month trial (MPK: n = 9; NMPK: n = 6). Participants with an MPK had significantly higher Prosthetic Limb Users Survey of Mobility (p = .01, Hedges' g: 1.70), Activity-specific Balance Confidence (p = .01, Hedges' g: 1.75), and Return to Normal Living Index (p = .05, Hedges' g: 0.54) scores compared to patients with NMPK. No other outcomes significantly differed between groups; effect sizes (0.47-1.75) across mobility outcomes indicated better outcomes in the MPK group.

Enrollment goals were limited by the COVID-19 pandemic, but all 15 participants who received a study prosthesis finished the 3-month pilot study. The MPK group generally had better 3-month outcomes than the NMPK group, but few statistically significant differences were found due to the small sample size and heterogeneity within groups. Results from this pilot study can inform and power future studies that compare MPKs and NMPKs in early rehabilitation.