Survival at 11 to 21 years for 779 Metasul® metal-on-metal total hip arthroplasties

Background: Total hip arthroplasties (THAs) bearing is one of the most important factors for hip replacement because THA survival depends on it. Metal-on-metal (MoM) bearing has lower wear than metal-on-polyethylene but lot of aseptic loosening decrease utilization. We analyze the survival rate of 28 mm Metasul (R) bearings after a mean follow-up of 12.9 years. Methods: The main objective of this study was to evaluate the survival of the MoM. We evaluate 779 consecutive THAs performed between January 1995 and December 2005 for primary osteoarthritis, congenital dysplasia classified Crowe I, or rheumatoid arthritis. Survival rate was calculated by the Kaplan-Meir method. The association between survival and age, gender, body mass index (BMI), and surface coating was investigated with a proportional odds model. The clinical assessment included Oxford score. Results: Six hundred fifty-two THAs were reviewed. Sixty-two revisions (9.5%) were performed including 34 aseptic loosening and 11 deep infections. The survival for prosthesis with any reason at 20 years was 87% (confidence interval (CI) 83-90.2) for aseptic loosening at 20 years was 90.1% (CI 87-93.8). There was no association with age, BMI, and surface coating. Gender was significant with lower aseptic loosening for men, hazard ratio = 0.45,pvalue = 0.035. Oxford score was 57 +/- 6.7 (19-60). Conclusion: The survival rate of Metasul was well and seems to be like our clinical finding. However, radiographic aseptic loosening without surgery is not included in the survival rate. The Oxford score was very good with a lot of patients with asymptomatic hip.