Physiological-Like Testing of the Dislocation Stability of Artificial Hip Joints

Dislocation of total hip replacements (THR) is a major reason for revision procedures. Dislocations may be caused by a prior prosthetic or bony contact (impingement) or by dynamic forces leading to spontaneous separation. Contributing factors are, above all, implant position and design and soft tissue condition. In order to enable evaluation of THR stability under physiological and reproducible conditions within an experimental setup, a novel hardware-in-the-loop (HiL) joint simulator has been developed. A six-axes industrial robot with a 6-DOF force-torque sensor moves and loads real THR components in a closed control loop with a musculoskeletal multibody model. By HiL simulation of load cases with a high tendency to impingement and subsequent dislocation, contributing factors can be identified.