Motion of the Intermediate Component of Eccentric Tripolar Total Hip Arthroplasty Prosthesis

Principal Investigator: Daniel J. Berry, M.D.
Project Coordinator: Qingshan Chen — chen.qingshan@mayo.edu

Figure 1: Custom made testing device.

Tripolar hip prosthesis is suggested as a method to reduce the occurrence of dislocation, which the most common complication after total hip arthroplasty. The tripolar hip prosthesis has two bearing surfaces: the outer bearing surface between the acetabular cup and an intermediate component, and the inner bearing surface between the intermediate component and the femoral head component. While the underlying mechanism by which tripolar prostheses reduce the dislocation remains unknown, it is believed to be related with the motion of the intermediate component. The present study aims to investigate in-vitro the motion of the intermediate component of a tripolar prosthesis using video-based motion analysis under varying loading conditions (Fig. 1). The results showed that the motion of the eccentric tripolar prosthesis is controlled by the direction of the joint contact force and can be affected by the suction force or the friction.