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

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