Metabolic Cost of Walking With Passive vs. Powered Prosthetic Knees Among Persons With Limb Loss

Inclusion Criteria: * Males and Females with unilateral knee disarticulation or transfemoral (KD/TF) amputation. * a body mass greater than 49Kg and less than 117Kg * 18-75 years of age * Have an ambulation potential of K3 or K4 * Use a prosthesis daily for walking or sports activities * No less than six months of experience with a prosthesis * No socket issues or changes in the last six weeks * No residual limb pain affecting functional ability. Exclusion Criteria: * Cannot walk at different speeds (MCFL K0-K2) * Limb-loss below the knee or through the hip * More than one amputation. * Uses an assistive device for walking * Uncontrolled edema in leg compartments * Compromised skin of the residual limb or contralateral foot * Are 180 days or less post-amputation * Pregnant (self-reported)