Influence of the manufacturing finishing on the nano-scale wear resistance at the taper-trunnion interface in hip implants

Micromotions at the taper-trunnion interface of modular hip replacements has been demonstrated to result in tribocorrosive damage to the surfaces and the generation and release of metallic particles and ions into the body. When Cobalt Chromium Molybdenum (CoCrMo) alloys are one of the interfacial surfaces, these particles and ions can initiate adverse reactions to the periprosthetic tissues, pain and the need to revise the implant. Tapers and trunnions are manufactured through a machining process which influences their surface finish, but also the surfaces metallic microstructure. In the case of the CoCrMo, the deformation results in grain refinement and work hardening of the alloy when compared with the bulk alloy, changing the properties. This study investigates the metallurgy, and mechanics and tribological performance of the taper and trunnion surface with respect to the bulk alloy to highlight the effect of the manufacturing processes in three commercial systems.