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Journal of Bone and Joint Surgery - British Volume, Vol 85-B, Issue 6,
913-917.
doi: 10.1302/0301-620X.85B6.14166 Copyright © 2003 by British Editorial Society of Bone and Joint Surgery Levels of metal ions after small- and large-diameter metal-on-metal hip arthroplastyM. T. Clarke, FRCS (Trauma & Orth), Assistant ProfessorOrthopaedic Surgery, SUNY-Upstate Medical University, 550 Harrison St, Suite 128, Syracuse, New York 13202, USA. P. T. H. Lee, MRCS, Clinical Research Associate The Orthopaedic Research Unit, Cambridge University, Cambridge CB2 2QQ, UK. A. Arora, FRCS, Research Fellow; and R. N. Villar, MS, FRCS, Consultant Orthopaedic Surgeon The Cambridge Hip and Knee Unit, BUPA Cambridge Lea Hospital, 30 New Road, Impington, Cambridge CB4 9EL, UK. Correspondence should be sent to Mr M. T. Clarke. Metal-on-metal (MOM) bearings for hip arthroplasty are increasing in popularity. Concern remains, however, regarding the potential toxicological effects of the metal ions which these bearings release. The serum levels of cobalt and chromium in 22 patients who had undergone MOM resurfacing arthroplasty were compared with a matched group of 22 patients who had undergone 28 mm MOM total hip arthroplasty (THA). At a median of 16 months (7 to 56) after resurfacing arthroplasty, we found the median serum levels of cobalt and chromium to be 38 nmol/l (14 to 44) and 53 nmol/l (23 to 165) respectively. These were significantly greater than the levels after 28 mm MOM THA which were 22 nmol/l (15 to 87, p = 0.021) and 19 nmol/l (2 to 58, p < 0.001) respectively. Since the upper limit for normal patients without implants is typically 5 nmol/l, both groups had significantly raised levels of metal ions. MOM bearings of large diameter, however, result in a greater systemic exposure of cobalt and chromium ions than bearings of small diameter. This may be of relevance for potential long-term side-effects. It is not known to what extent this difference is due to corrosion of the surfaces of the component or of the wear particles produced. This article has been cited by other articles:
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