The John Charnley Award: Metal-on-Metal Hip Resurfacing versus Large-diameter Head Metal-on-Metal Total Hip Arthroplasty: A Randomized Clinical Trial
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Resurfacing arthroplasty has become an attractive option for young patients who want to maintain a high activity level. One recent study reported modestly increased activity levels for patients with resurfacing compared to standard total hip arthroplasty (THA). We conducted a prospective randomized clinical trial to compare clinical outcomes of resurfacing versus large-head metal-on-metal total hip arthroplasty. We randomized 107 patients deemed eligible for resurfacing arthroplasty to have either resurfacing or standard THA. Patients were assessed for quality-of-life outcomes using the PAT-5D index, WOMAC, SF-36, and UCLA activity score. The minimum followup was 0.8 years (mean, 1.1 years; range, 0.8–2.2 years). Of the 73 patients followed at least one year, both groups reported improvement in quality of life on all outcome measures. There was no difference in quality of life between the two arms in the study. Serum levels of cobalt and chromium were measured in a subset of 30 patients. In both groups cobalt and chromium was elevated compared to baseline. Patients receiving a large-head metal-on-metal total hip had elevated ion levels compared to the resurfacing arm of the study. At 1 year, the median serum cobalt increased 46-fold from baseline in patients in the large-head total hip group, while the median serum chromium increased 10-fold. At 1 year, serum cobalt was 10-fold higher and serum chromium 2.6-fold higher than in the resurfacing arm. Due to these excessively high metal ion levels, the authors recommend against further use of this particular large-head total hip arthroplasty.
Level of Evidence: Level I, randomized clinical trial. See Guidelines for Authors for a complete description of levels of evidence.
KeywordsFemoral Head Femoral Component Bearing Surface Abduction Angle Chromium Level
We thank Timothy Pearce MD, FRCS(C) and Robert Korbyl MD, FRCS(C) for recruiting patients at Red Deer General Hospital; Lorna Ottley, Daphné Savoy, Jennifer Zander and Karen Smith for patient recruitment and study coordination; and Eric Sayre for his help with the statistical analysis.
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