Tripolar hip replacement for recurrent prosthetic dislocation.

An innovative treatment is described for unstable total hip arthroplasty that uses a large inside diameter acetabular cup and a bipolar femoral head sized to approximate the diameter of the normal hip. Eight consecutive patients with recurrent prosthetic dislocations were treated with this tripolar hip. Joint stability was achieved in all patients, who have an average of 4.2-years' followup (range, 2.6-6.3 years).