Bipolar socket in protrusio acetabuli. 3-6-year study.

Twenty-two hips with protrusio acetabular deformity in 14 patients received bipolar socket hemiarthroplasty combined with bone-grafting to the medial wall defect. The surgical technique included crushed cancellous grafting and attention to adequate rim contact for the socket. Results were evaluated at a mean of 54 months after surgery (range, 36-76 months). On hip had thigh pain attributable to a loose femoral component. No patient had groin pain at follow-up examination. A satisfactory range of motion was achieved in all but one case, and an average increase of 40 points in the Harris hip score was realized. Radiographically, all acetabuli were returned to a more normal, inferolateral position. Socket migration (measured relative to the teardrop) in the range of 3-7 mm was noted in 5 hips; the remaining 17 hips displayed no or minimal migration of the socket (< 3 mm). The bipolar socket with crushed cancellous graft appears to be an acceptable surgical alternative in protrusio acetabuli, providing a reliable relief of pain, satisfactory functional results, and a restoration of acetabular bone stock in the majority of cases.