Comparison of the Long-Term Clinical Results of Resurfacing Hip Arthroplasty for Japanese Patients Who Have Osteonecrosis versus Those Who Have Other Diagnoses.

Abstract

This study investigated the long-term (mean 13.5 years) clinical results of resurfacing hip arthroplasty (RHA) in Japanese patients who had osteonecrosis (ON) and compared the results with those of patients who had other diagnoses. A consecutive series of 65 hips (50 men and 15 women), with 30 in the ON group and 35 hips in the nonosteonecrosis (non-ON) group, were included. The mean follow-up period was 13.5 years (range, 10 to 20). The Japanese Orthopaedic Association hip-scoring system was used to clinically evaluate hip function. In radiological assessment, the stem-shaft angle and inclination of the acetabular component were evaluated. Adverse reactions around the RHA were evaluated with Magnetic Resonance Imaging. Data on postoperative complications were retrieved from the medical records. Kaplan‒Meier analysis was used to compare the survival rate between the two groups. Significant improvement was observed between the preoperative and final follow-up Japanese Orthopaedic Association hip scores in both groups. Radiological assessments revealed no major changes in either group. There were none of the hips that required revision for adverse reactions. Femoral neck fractures were observed in three cases (ON group, n = 2; non-ON group, n = 1) and aseptic loosening of the femoral or acetabular component in two cases (ON group, n = 1; non-ON group, n = 1). Additional operations were performed for three hips in the ON group and two in the non-ON group. The 15-year survival rate was 90 and 94% in the ON and non-ON groups, respectively (P = 0.53). In the ON group, the 15-year survival rate was 92% in Type C1 and 90% in Type C2 cases (P = 0.84). This study showed satisfactory mean 13.5 years clinical results of RHA in Japanese patients who had ON.