148. RANDOMISED CONTROLLED TRIAL COMPARING METAL ON METAL VERSUS METAL ON POLYETHYLENE ARTICULATION IN THA

Abstract

Purpose: A single blind prospective randomised controlled trial comparing the Metal-on-polyethylene articulation with the metal-on-metal articulation in THA.

Method: The clinical and radiological findings of the consecutive patients who were enrolled in the RCT at the participating centres were recorded prospectively. The clinical evaluation was performed with the Harris scoring system as well as the Oxford Hip Scoring Sheet. The computer randomised option was revealed to the operative surgeon only after the patient was anaesthetised, during the recruitment period (June 1998 to July 2004). Of the total of 378 patients, 2 died prior to the final review and 63 were lost to follow-up. The final study group contained 315 patients, with 159 patients in the metal-on-polyethylene group and 156 patients in the metal-on-metal group.

Results: The indication for the hip arthroplasty for majority (309 patients) was primary osteoarthritis. The average age at the time of the surgery was 68.2 years and the average duration of follow-up was 85 months (42–115). There was an improvement of the Oxford hip scores from an average of 37 per-operatively to 16 postoperatively. The Harris hip scores also improved from an average of 47.0 pre-operatively to 87.3 post-operatively. The patient groups were statistically similar with respect to age, sex and duration of follow-up, and the final outcome scores revealed no statistical difference between the two groups.

Conclusion: The clinical results obtained with the use of the articulation are comparable to those obtained by the metal-on-polyethylene articulation encouraging the use of this alternative bearing surface.