Metallosis: metal ion release from metal-on-metal joint surface replacement - current concerns and future problems

Abstract

Since its innovation, joint replacement surgery has offered relief from the pain and functional limitation of destructive or degenerate joint disease. The search for the ideal material continues over 120 years later. Recently, using metal-on-metal bearings for younger patients has become the trend to avoid excess wear in high demand patients in the hope of reducing the need to revision surgery. Initial evidence suggested these prostheses offered a durable, functional safe joint that was less likely to be revised than the standard metal and polyethylene joint. A body of evidence is growing rapidly to suggest that metal-on-metal joints are associated with local tissue reactions - metallosis - cellular toxicity, increased serum metal ion concentrations, organ deposition of metal ions, higher rather than lower rates of revision surgery and no functional advantage over any other type of joint replacement. We will consider the reasons for metal ion release; the cellular, local tissue and systemic effects of metal ions and the patient risk and presentation. From the evidence reviewed, serious consideration should be given to the future use of metal-on-metal joint bearings and a suggested follow up plan for patients with such joints is identified and reproduced. Biomedical Reviews 2011; 22: 57-64.