CLINICAL OUTCOME OF RESURFACING ARTHROPLASTY IN PATIENTS WITH DEVELOPMENTAL DYSPLASIA OF THE HIP

Abstract

There is only a paucity of information on the outcome of resurfacing arthroplasty in patients suffering from hip osteoarthritis secondary to developmental dysplasia (DDH). When performing arthroplasty in dysplastic hips, the anatomic abnormalities offer reconstructive challenges, in particular in resurfacing. The present study was therefore conducted to address the following questions: Can hip resurfacing arthroplasty provide satisfactory clinical results in patients with DDH? Can the patients return to sports and recreational activities? Can the hip biomechanics be restored? And finally, can surface arthroplasty reestablish a normal, symmetric gait pattern? The study comprised 24 consecutive patients (32 hips) with a mean age of 44.2 years who underwent surface replacement due to hip osteoarthritis secondary to DDH. Surgery was performed by two senior surgeons using either the Durom implant or the Birmingham Hip Resurfacing prosthesis, dependent on the surgeon’s preference. At a mean follow-up of 43 months, all patients were evaluated cross-sectionally. We assessed clinical and radiographical data and investigated spatiotemporal gait parameters using an electronic mat. The Harris Hip Score improved from 54.7 +/−13.3 to 97.3 +/−5.2 (p< 0.001) and University of California at Los Angeles (UCLA) activity levels increased from 5.3 +/−2.0 to 8.6 +/−1.6 (p< 0.001), respectively. Hip flexion improved from 95.7° +/−16.5° to 106.7° +/−10.6° (p< 0.001). At a mean of 11.2 +/−4.8 weeks after surgery, all patients returned to sports activity. They participated in a mean of 6.0 +/−2.6 different disciplines, 2.8 +/−1.3 times and 4.1 +/−3.6 hours per week. The most common disciplines were cycling, swimming, exercise walking and downhill-skiing. Spatiotemporal parameters of gait demonstrated a symmetrical gait pattern without major differences to normative data. Both, the hip lever arm ratio and the femoral offset increased significantly (p< 0.001) from 0.48 +/−0.07 to 0.57 +/−0.08 and from 39.3 +/−8.2 mm to 45.6 +/−6.2 mm, respectively. Grade I heterotopic ossifications were seen in two hips, there were no Grade II or III ossifications. Two surface replacements failed, both failures could be attributed to surgical errors. The surface arthroplasty risk index was 3.2 +/−1.4 for the entire cohort and 4.5 for the revision cases. Femoral radiolucencies were detected in ten of the remaining 30 hips. The present study demonstrated that hip resurfacing achieved satisfactory clinical results in patients with hip osteoarthritis secondary to DDH. The failure rate of 6.3% did not reach our expectations, however, both failures could be attributed to surgical errors. Further follow-up is nevertheless of utmost importance to assess the significance of femoral stem radiolucencies in this young and active group of patients.