An Important Contribution to Our Understanding of the Performance of the Current Generation of Metal-on-Metal Hip Replacements

Abstract

It is hard to overstate the importance of implant retrieval analysis in the development of successful orthopaedic devices. Given the enormous complexity of the musculoskeletal system, no amount of preclinical testing, joint simulation, and analytic modeling can fully predict the performance of orthopaedic implants. Despite the application of the most sophisticated methodologies available during the 1990s when so-called alternative bearings were being developed for total hip arthroplasty, there was insufficient information to predict, among other things, squeaking of ceramic-on-ceramic bearings and the adverse local tissue reactions that have been widely reported in association with metal-on-metal bearings. Implant retrieval analyses provide important and unique insights into the in situ performance of orthopaedic devices and provide critical clues into mechanisms of failure and success, the latter being determined by postmortem retrieval analyses. The findings from implant retrieval studies also provide the necessary end points for implant designers to develop preclinical testing models. Biomechanical testing, joint simulations, and analytic modeling will only be predictive of implant performance if the failure mechanisms, or end points, of the testing and modeling are congruent with the failure mechanisms observed on retrieved devices. The study by Hart et al. is an important contribution to our understanding of the performance of the …