Abstract: A prosthesis includes a knee joint having movable elements geared together and rotatable about axes located rearward of a vertical bearing axis of the prosthesis. A foot member is pivoted about a horizontal ankle joint and is urged by a first spring toward the toe-down position and by a second spring toward the toe-up position. The first spring is stronger than the second spring. A tie rod is connected from the knee joint to the first spring to reduce the force applied by the first spring so that, when the knee joint is bent and the foot is raised from the ground to move the prosthesis forward to a straight-knee position, the toe of the foot is raised to clear the ground. The axis of the knee, being in a position aft of the vertical axis, tends to stably support the leg when it is in its weight-bearing position.