Metal-on-metal versus metal-on-polyethylene bearings in total hip arthroplasty: a matched case-control study.

This case-control study was performed to investigate the hypothesis that metal-on-metal (M-M) bearings reduce the risk of aseptic component loosening when compared with metal-on-polyethylene (M-PE) bearings. Cases were identified from a computerized joint database as patients who had received a primary total hip arthroplasty using an M-M or M-PE bearing and had documented revision or radiographic loosening of the stem or cup. Multiple controls were matched to each case for gender, age, diagnosis, hospital, operation date, follow-up, stem type, and cup design. Odds ratios were determined to identify the risk of component loosening for either bearing surface. In all, 505 cases and 1,605 controls were identified. M-M bearings demonstrated a lower risk of aseptic stem and/or cup loosening than M-PE bearings; however, this was not statistically significant.