OBJECTIVETo discuss long-term clinical results of using Zweymüller cup to treat protrusio acetabuli.

METHODSFrom May 1998 to September 2006, 31 patients with 39 hips diagnosed protrusio acetabuli were treated with Zweymüller cup in total hip arthroplasties or revisions. There were 12 men and 19 women with average age of 57.6 years (from 30 to 82 years). The reasons causing protrusio acetabuli were as followed: rheumatoid arthritis 3 cases 6 hips, osteoarthritis followed femoral head necrosis 7 cases 12 hips, acetabular wear after hemi-arthroplasty 11 cases 11 hips and acetabular component loosening 10 cases 10 hips. During all operations, Zweymüller cup was used to fix the acetabular part.

RESULTSAll cases were followed up 6 months and one year after operations. Two patients with 3 hips were died for lung cancer and acute myocardial infarction respectively. Twenty-four cases with 31 hips got recent follow-up with average 7.4 years (from 5.0 to 11.5 years). The average Harris score improved from 31.0 (from 14 to 61) preoperatively to 84.7 (from 70 to 95) postoperatively. There was one infection in right hip after bilateral hip arthroplasty treating by removal prosthesis and cement spacer insert. But until now this patient still did not get revision for her internal medicine. One rheumatoid arthritis patient with two-stage bilateral hip arthroplasty was found slight internal migration and loosening line of left acetabular component, but the patient had no pain with good hip function. All other cases had good hip functions and were very satisfied with clinical results.

CONCLUSIONUsing Zweymüller cup to treat protrusion acetabuli can get strong fixations and perfect medium and long-term clinical results for over 7.4 years.