A brief review of test methodologies for surface-engineered biomedical implant alloys

Surface engineering opens up very many exciting opportunities for new designs of bio-medical implant devices like total joint replacements (TJRs). The development of new bearing surface materials for such devices, however, is a very slow process. This is due to the longevity of in vitro wear tests, biocompatibility studies, clinical trials and final adoption. Given the diversity of new bearing surface materials that modern surface engineering can make possible, there is a clear need to develop valid and rapid screening tests. A brief review of possible accelerated test methods, developed at Leeds, is presented. The tests are designed to evaluate tolerance to: (i) mechanical (third body abrasion) damage; (ii) corrosion and; (iii) corrosion-wear. By referring to specific investigations throughout, the scope of such tests is fully illustrated. It is shown that both mechanical and chemical attributes for a given surface engineering design are important in the realisation of the overall goal of improved bearing surfaces for TJRs.