Design and optimization of a hip disarticulation prosthesis using the remote center of motion mechanism

BACKGROUND: Hip disarticulation prostheses (HDPs) are not routinely seen in clinical practice, and traditional hip prostheses rotate around an axis at the front side of the pelvic socket. OBJECTIVE: This study proposes a mechanism to restore the rotation center to the acetabulum of the amputated side and uses comparative experiments with traditional HDP to verify the validity of the novel design. METHODS: A double parallelogram design of HDP based on a remote center of motion (RCM) mechanism was presented in this paper. Optimization was achieved by a genetic algorithm with the maximal integral size and minimal driving force of the mechanism. RESULTS: The prototype was developed by final optimal results and tested by a hip disarticulated amputee. Testing results revealed that the RCM-HDP improved the range of motion of the hip prosthesis by 78%. The maximal flexion of the assorted prosthetic knee was closer to the sound side than a traditional HDP by 15%. CONCLUSION: The proposed RCM-HDP promoted the kinematic performance and symmetry of the hip prosthesis compared to the traditional design.