Prosthetic intervention effects on activity of lower-extremity amputees.

Objective: To investigate the effect of prosthetic interventions on the functional mobility of lower-extremity amputees.

Design: Crossover with repeated measures.

Setting: Household and community environment.

Participants: Twelve transtibial and 5 transfemoral amputees.

Interventions: For transtibial amputees, shock-absorbing versus rigid pylons. For transfemoral amputees, C-Leg versus Mauch SNS knees.

Main Outcome Measures: Daily activity level (step count) and duration (minutes of activity).

Results: Pylon type had no effect on the daily activity level or duration of transtibial amputees. Knee type had no effect on the daily activity level or duration of transfemoral amputees. Transtibial amputees were more active on weekdays (3079+/-1515 steps/d) than weekends (2386+/-1225 steps/d) (P=.007). In general, lower-extremity amputees perform numerous short-duration bouts of activity (1-2 min) consisting of fewer than 17 steps/min, but activities of more than 15 minutes in duration were relatively rare (<1 per day).

Conclusions: Intervention had no effect on amputee activity level and duration. Higher weekday activity levels of transtibial amputees suggest their vocational activities are more demanding than recreational activities. The fitting, alignment, and design of prosthetic components should be optimized for 1 to 2 minute bouts of activity consisting of only a few dozen steps.