Dislocation is a common reason for revision following
total hip replacement. This study investigated the relationship between the bearing surface and the risk of revision due to dislocation. It was based on 110 239 primary
total hip replacements with a diagnosis of
osteoarthritis collected by the Australian
Orthopaedic Association National
Joint Replacement Registry between September 1999 and December 2007. A total of 862 (0.78%) were revised because of dislocation. Ceramic-on-ceramic bearing surfaces had a lower risk of requiring revision due to dislocation than did metal-on-polyethylene and ceramic-on-polyethylene surfaces, with a follow-up of up to seven years. However, ceramic-on-ceramic implants were more likely to have larger prosthetic
heads and to have been implanted in younger patients. The size of the
head of the femoral component and age are known to be independent predictors of dislocation. Therefore, the outcomes were stratified by the size of the
head and age. There is a significantly higher rate of revision for dislocation in ceramic-on-ceramic bearing surfaces than in metal-on-polyethylene implants when smaller sizes (< or = 28 mm) of the
head were used in younger patients (< 65 years) (
hazard ratio = 1.53, p = 0.041) and also with larger (> 28 mm) and in older patients (> or = 65 years) (
hazard ratio = 1.73, p = 0.016).
