Robot-Based Testing of Total Joint Replacements

Instabilities of artificial joints are prevalent complications in total joint arthroplasty. In order to investigate failure mechanisms like dislocation of total hip replacements or instability of total knee replacements, a novel test approach is introduced by means of a hardware-in-the-loop (HiL) simulation combining the advantages of an experimental with a numerical approach. The HiL simulation is based on a six-axes industrial robot and a musculoskeletal multibody model. Within the multibody model, the anatomical environment of the correspondent joint is represented such that the soft tissue response is considered during an instability event. Hence, the robot loads and moves the real implant components according to the data provided by the multibody model while transferring back the relative displacement of the implant components and the resisting moments recorded. HiL simulations provide a new biomechanical testing tool which enables comparable and reproducible investigations of various joint replacement systems with respect to their instability behaviour under realistic movements and physiological load conditions.