Resurfacing arthroplasty for hip dysplasia： evaluation of treatment outcome

Abstract

Objective To assess the functional restoration in patients with developmental dysplasia of the hip （DDH） who underwent hip resurfacing arthroplasty and to determine whether greater abduction angle of the acetabular component is relat- ed to larger diameter of femoral head component. Methods We reviewed 34 DDH cases （9 hips of 8 males and 25 hips of 24 fe- males, mean age 44.6_＋ 11.85 years at the time of surgery） on whom we performed hip resurfacing arthroplasty （HRA） from October 2006 to September 2009. The total hip Arthroplasty （THA） group was consisted of 35 DDH cases （8 hips of 8 males and 27 hips of 25 females, mean age 43.7±10.4 years at the time of surgery）. All operations were performed by the same doctor over the same peri- od. Assessment of the functional hip scores was conducted by Harris Hip Scores. A radiographic study was also performed to evalu- ate the implants stability and abduction angle of the acetabular components. All the data was analyzed with Kolmogorov-Smirnov method. Results The mean follow-up was 6.2 years in the HRA group. The Harris Hip Score improved from 54.9±13.2 to 97.3±6.2 after the surgery. The mean abduction angle of the acetabular component was 51.6°±5.33°, hip flexion was 127°±6.9° and mean diameter of femoral head was 46.5±1.5 mm. The mean follow-up was 5.9 years in the THA group. The Harris Hip Score im- proved from 51.6±19.7 to 95.6±7.9 after the surgery. The mean abduction angle of the acetabular component was 43.9°±4.90°, hip flexion was 117°±4.2°. There was no failure of the prosthesis, peri-prosthetic fracture and infection in either group. There was sig- nificant difference in the abduction angle of the acetabular component （P 〈 0.05） and flexion of the hip between the two groups （P 〈 0.05）. Conclusion Patients in the HRA group had a better functional restoration and larger range of motion. Furthermore, a larger diameter of femoral head component could be achieved by placing the acetabular component in a greater abduction angle, which may contribute to a better long-term stability. Key words: Hip dislocation, congenital; Arthroplasty, replacement, hip; Prosthesis fitting