No superiority of cemented metal-on- metal over metal-on-polyethylene total hip arthroplasty in a randomized trial at 10-year follow-up

In a randomized controlled trial, 102 cemented Stanmore 28-mm metal-on-metal total hip arthroplasties (THAs) were compared to 98 metal-on-polyethylene THAs in 195 patients. At a mean follow-up of 10 years, 11 patients (11 hips) were lost to followup, 53 patients (55 hips) died, and 6 patients (6 hips) underwent revision. Average age of the surviving patients was 79 years. Harris Hip Scores and Oxford Hip Scores had increased significantly in both groups (p<.001). Ten years postoperatively, mean Harris Hip Score was 86 in the metal-on-metal patients and 87 in the metal-on-polyethylene patients (p=.441); Oxford Hip Scores were 27 and 24, respectively (p=.494). Wear was present in 30 of 52 polyethylene cups. Periprosthetic radiolucencies were seen in 57% of the metal-on-metal patients and in 52% of the metal-on-polyethylene patients (p=.680); they were mainly seen in DeLee & Charnley’s zones 1 and 2. Serum cobalt and chromium concentration were higher in the metal-on-metal group (cobalt 1.1, chromium 1.0 vs 0.5 and 0.5 μg/L, respectively; p<.001). Patients with high ion levels (maximum 9.5 and 11 μg/L, respectively) all showed high Harris Hip Scores and few or no periprosthetic radiolucencies, and none were revised. Ten-year survival was 95.5% in the metal-on-metal group (4 revisions) and 96.8% in the metal-on-polyethylene group (2 revisions; p=.402). All revisions were indicated for aseptic loosening. One case of aseptic lymphocytic vasculitis-associated lesions (ALVAL) and no pseudotumors were observed. The absence of clinical superiority of the cemented metal-on-metal bearing and the concerns over their biological effects have led us to favor the cemented metalon-polyethylene THA. 46