Metal-on-crosslinked polyethylene in total hip arthroplasty - an excellent combination at fifteen to twenty years of follow-up.

PURPOSE: Cross-linked polyethylene (PE) has been used with great clinical success in total hip arthroplasty (THA) since its debut in the late 1990's. However, reports regarding this bearing couple near the end of its second decade of service are still scant. The aim of this study was to first determine the long term clinical and radiological results and second Investigate what factors affect wear rates using a metal-on-crosslinked PE bearing articulation.

METHODS: 55 THAs using a single brand of cross-linked liner, cementless cup and 28 mm hip ball were performed in 44 patients. Age, sex, Charlson Comorbidity Index (CCI) and need for revision surgery were recorded. Linear and volumetric wear was determined using the Martell method.

RESULTS: Mean age at operation was 51.2 (29-73 ± 12.1) years. Mean duration of follow-up was 16.9 years (range 15.0-20.1 ± 1.1 years). Osteolysis was not present in the latest follow-up radiographs. Median linear and volumetric wear rate was 0.038 mm/year (95% CI 0.032-0.047) and 7.115mm3/year (95% CI 6.92-17.25) respectively. Acetabular component position was not found to be related to both linear and volumetric wear. No significant difference was found in the linear and volumetric wear rates of thinner and thicker liners (8 mm or below and > 8 mm) (p = 0.849 and p = 0.64 respectively).

CONCLUSION: Metal-on-crosslinked PE is associated with low linear and volumetric wear rates which has virtually obviated osteolysis and has translated to excellent survivorship even at long term follow up. In-vivo oxidation does not appear to be of clinical concern at this point.