The performance of gamma- and EtO-sterilised UHWMPE acetabular cups tested under severe simulator conditions. Part 1: role of the third-body wear process

Abstract

Due to its excellent combination of properties, ultra-high-molecular-weight-polyethylene has been used for the last 30 years in the replacement of damaged articulating cartilage for total joint replacement surgery. However, in some cases, wear, failure and delamination have been observed. Polyethylene performance may be affected by oxidation during consolidation of the resin, sterilisation of the finished specimens and post-irradiation storage. In order to evaluate the influence of the sterilisation method (gamma-irradiation and ethylene oxide(EtO)-treatment) and third-body particles on the ultra-high-molecular-weight-polyethylene wear behaviour, gamma- and EtO-sterilised ultra-high-molecular-weight-polyethylene acetabular cups were tested against CoCrMo femoral heads in a hip joint simulator run for 2.5 million cycles in bovine calf serum in the presence of third-body PMMA particles. Weight loss measurements revealed that the gamma-sterilised acetabular cups exhibited a significantly lower wear rate than those EtO-sterilised. Moreover, significant differences were found for each type of sterilisation between the gravimetric wear trends obtained until 2.5 million cycles in the presence and in the absence of PMMA particles.