Metal-on-metal problems: Diagnosis and management

Metal-on-metal total hip arthroplasty can have failure mechanisms not commonly seen with metal on polyethylene bearings because of host reactions to the metal debris. Besides being more subject to edge-loading and accelerated wear if implants are malpositioned, certain patients can have a immunological response to the wear particles. Furthermore, the interaction of different metals at the taper junction of a metal-on-metal total hip can lead to corrosion products that may engender an inflammatory reaction. Thus, the diagnosis of metal-on-metal problems can be difficult and requires the use of diagnostic modalities such as metal ion measurement and metal artifact reduction imaging techniques. An algorithm for the evaluation of both asymptomatic and symptomatic patients will be presented.