The evolution and modern use of metal-on-metal bearings in total hip arthroplasty.

Metal-on-metal bearings have been used in total hip arthroplasty for decades. Because younger patients with higher physical demands are now being treated with hip arthroplasty, the popularity and use of metal-on-metal bearings has increased over the past 10 years. New concerns, however, have emerged regarding the percentage of patients with a hypersensitivity reaction or pseudotumor formation after arthroplasty with these bearings. These concerns have raised questions concerning long-term outcomes for patients treated with metal-on-metal bearings. It is important for orthopaedic surgeons to review these issues so that better educated decisions can be made in treating their patients.