Correlation between early and late wear rates in total hip arthroplasty with application to the performance of marathon cross-linked polyethylene liners

Laboratory simulations are typically used to assess the performance of new bearing surfaces for total hip arthroplasty. However, the ability of in vitro studies to accurately predict clinical wear performance remains uncertain. Using computer-assisted radiographic measurement techniques, this study found that the average wear rate based on early (2–3 years) clinical follow-up is representative of the average long-term wear rate for a population. Based on early wear data, Marathon polyethylene liners, cross-linked with 5.0 Mrad of gamma irradiation, are wearing at a mean rate of 0.08 mm/yr. This rate is about half that of non-cross-linked polyethylene but represents a more modest wear reduction than in vitro studies have predicted. If 5 to 10-year Marathon wear data corroborate our short-term results, early clinical wear data should be used to validate hip simulator studies.