Failure of Metal-on-Metal Total Hip Arthroplasty Mimicking Hip Infection

New-generation metal-on-metal bearings made from cobalt-chromium alloys for use in total hip arthroplasty are now being utilized worldwide. A hypersensitivity reaction to a metal-on-metal bearing is a rare but reported complication and is thought to be a novel mode of failure of these implants1,2. These reactions were initially observed in patients with first-generation bearings and are now being reported in association with the second-generation metal-on-metal bearings currently in use3-5. Characteristic histological changes in the periprosthetic tissues obtained during revision surgical procedures in these patients have suggested the development of an immunological response2,6.