Clinical results of conversion total hip arthroplasty after failed bipolar hemiarthroplasty

Total hip arthroplasty (THA) has been the most common surgery performed for complications of bipolar arthroplasty. We wanted to evaluate functional results and complications after conversion of bipolar hemiarthroplasty to THA in 25 patients followed for an average of 7.2 years. Indications for conversion included acetabular erosion with well-fixed femoral stem in 13 patients, acetabular erosion with femoral loosening in 8 patients, and periprosthetic fracture in 4 patients. The average Harris Hip Score improved from 41 (34 to 67) before conversion to 85 (65 to 95) at final follow-up. The average Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) score improved from 81 (41 to 96) before conversion to 17 (8 to 36) at final follow-up. Pain component of WOMAC improved from an average of 15 (7 to 20) to 4 (0 to 11). The stiffness component of WOMAC improved from 6 (2-8) to 30 (0-4) and the function component improved from 59 (36-68) to 17 (8-36). The complications included 2 recurrent dislocations, 2 dislocations, 1 acetabular loosening, and 1 trochanteric nonunion. One patient required revision of acetabular component. The conversion THA after symptomatic bipolar arthroplasty can offer reliable pain relief and functional improvement. The perioperative complications approximate those of revision THAs.