Toxicology of wear particles of cobalt-chromium alloy metal-on-metal hip implants Part I: Physicochemical properties in patient and simulator studies

Under well-functioning conditions, MoM hip implants have low wear rate and generate primarily oxidized Cr nanoparticles with minimal or no Co content. When there is surgical malpositioning, however, MoM hip implants have significantly higher wear rate and generate larger-sized wear debris (up to 1000 nm) that contain higher concentrations of Co. Future toxicology studies of MoM wear debris which are used to conduct risk assessments need to focus on particle characteristics relevant to those generated in patients or in properly conducted simulator studies.269