STANCE PHASE-CONTROL OF ABOVE-KNEE PROSTHESES - KNEE CONTROL VERSUS SACH FOOT DESIGN

This paper examines the role of the knee controller in relation to a SACH (Solid Ankle Cushioned Heel) foot during the stance phase of level walking. The three-dimensional gait mechanics were measured under two stance phase conditions. In the first set of trials, the amputee used a prosthesis with a conventional knee controller that allowed the amputee to maintain the knee joint in full extension during the stance phase. In the second set of trials, the prosthetic knee, during stance, echoed the modified kinematics of the amputee's sound (initial) knee that had been recorded during the previous sound stance phase. Analysis and interpretation of the data indicate the following: SACH foot design can strongly influence the walking mechanics independent of the knee controller; knee controller design and SACH foot design are mutually interdependent; and normal kinematics imposed on the prosthetic knee does not necessarily produce normal hip kinematics.