Use of the Charnley mini-offset bore acetabular component in severe acetabular dysplasia. A preliminary report

Nine total hip arthroplasties were performed in seven patients using the Charnley mini-offset bore acetabular component to assess its effectiveness in cases of severe deficiency of acetabular bone "stock." Preoperative diagnoses included seven chronically dislocated hips and two previously failed arthroplasties. The follow-up period averaged 49 months. Pain relief was dramatic in all patients, and all had increased ambulatory capacity after operation. No clinical loosenings or deep infections were encountered. The small outside diameter (36 mm) of this acetabular component requires only minimal bone removal from the acetabular bed. Its eccentrically positioned bore allows for adequate polyethylene thickness in the weight-bearing area. It also takes advantage of the low frictional torque of a small femoral head system.