Metallosis after metal-on-polyethylene total hip arthroplasty.

Metal debris should not be generated in a well-fixed, well-functioning metal-on-polyethylene total hip arthroplasty. However, surgeons sometimes encounter periprosthetic metallosis during revision hip surgery. Insert wear, fracture, or dislodgment in modular components may lead to articulation of the prosthetic head with the metallic shell and subsequent metallosis. Metallosis may occur with loose acetabular components as a consequence of fretting of the screws and shell screw holes or shedding of the ingrowth surface of the component. The femoral component can also be a source of metallosis: Wear of a titanium femoral head, loosening of rough surface finish from the femoral stem, and stem fracture all may result in metallic particles being deposited in periarticular tissues. Specific clinical and radiographic findings can help in differentiating these forms of failure and in planning surgery. When metallic debris-induced bone loss is recognized early, surgical intervention may limit its progression.