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.