Microprocessor-controlled Prosthetic Knees for Fall Safety

Inclusion Criteria: * Unilateral transfemoral or knee disarticulation limb loss. * 6 months or longer since time of limb loss. * Current user of a prosthesis with a non-microprocessor-controlled prosthetic knee. * Received a replacement prosthesis with a non-microprocessor knee in the past 4-24 months. * Clinician has deemed patient limited community ambulator (Medicare functional classification level K2). * In addition, Medicare functional classification level K2 as determined by at least one of the following criteria: 1. Houghton Score: 5-10 2. Prosthetic Limb Users Survey of Mobility (PLUS-M) T-Score: if amputation etiology is vascular disease/diabetes \<49.45, otherwise, \<36.75. 3. Amputee Mobility Predictor (AMPPRO) score: 27-42 collected within the last 24 months * Ability to read, write, and understand English. Exclusion Criteria: * Any health condition that would prevent safely completing trial activities. * Any individuals that weigh 275 lbs or more. * Any individuals who wear their prosthesis less than 3 days a week or less than a total of 24 hours a week * Individuals with a history of acute or chronic residual limb breakdown * Individuals with declining health status such that he/she subsequently reports reduced activity over the past 6 months