Dissociation and Intrapelvic Entrapment of a Dual-mobility Polyethylene Component

摘要

Background Dual-mobility bearings have gained popularity in recent years as a proposed method of reducing the risk of dislocation after primary and revision hip arthroplasties. Intraprosthetic dislocation, defined as dissociation of the smaller femoral head from the larger outer polyethylene head, is a known complication of these designs. Intraprosthetic dislocation typically requires reoperation and revision as closed reduction of intraprosthetic dislocations of these components is not effective. The small femoral head typically remains inside the large diameter acetabular component during intraprosthetic dislocation, thus the diagnosis may be missed if femoral head eccentricity is not identified on radiographs. Intraprosthetic dislocation leads to a free polyethylene bearing which typically stays in the joint space, however in theory, migration of the bearing is possible.