Failure in Bipolar Hemiarthroplasty for Femoral Neck Fracture in the Elderly

Purpose: We analyzed the cases which performed the conversion to total hip arthroplasty(THA) after bipolar hemiarthroplasty for femoral neck fracture in the elderly. Material and Method: A retrospective study was performed on 92 patients, 65 years of age and older, who sustained a femoral neck fracture and underwent bipolar hemiarthroplasty between March 1992 and February 1996. Excluding the infection cases, 9 cases were performed conversion to THA due to clinical and radiological failure within 5 years after hemiarthroplasty. The patients had a mean age of 72.5 years at the time of the operation. The causes of conversion to THA were acetabular cartilage erosion with intractable pain in 3 cases, proximal migration of acetabular cup in 3 cases, radiographic failure of the femoral stem (cement fragmentation, varus tilt, distal migration of the stem) in 2 cases and the wear of the polyethylene acetabular component and osteolysis in 1 case. Result: Conversion to THA was performed at average 4 years 5 months after index operation (range, 2 years 10 month - 5 years). In 6 cases, acetabular cup was replaced. In 3 cases, acetabular cup and femoral stem were replaced. During average 3 years follow-up, average Harris hip score was improved from 57.5 before surgery to 82.0 at the time of the final follow-up. The result was checked as above fair in 88.9%. The clinical symptom was improved in all patients and there were no clinical or radiological complications during that period. Conclusion: We concluded that the main cause of conversion to THA after bipolar hemiarthroplasty was acetabular erosion or proximal migration and on that cause, revision surgery was needed. After conversion to THA, clinically satisfactory results were obtained in all cases.ope