Ankle-knee synchronous in a new endoskeletal above-knee prosthetic mechanism: a preliminary report

A new above-knee prosthetic mechanism with synchronous motions of the knee and ankle has been designed based on kinematic principles. Knee flexion is synchronized with ankle dorsiflexion by a synchronizer rod and lever. Unlike other above-knee units, the knee joint is aligned about one inch in front of a line between the hip and the ankle joints, which appears to decrease the energy requirements of gait. The swing-phase control system provides constant friction during ordinary cadence and variable friction during rapid swinging of the leg. The addition of a quadrilateral socket, a modified SACH foot and a cosmetic foam plastic cover provides the complete endoskeletal above-knee prosthesis. The resulting gait has been found to be faster, easier and more natural, and the three optional knee settings serve the needs of different amputees and activities.