Few papers have described results after periacetabular osteotomy (PAO) and risk factors for conversion to total hip arthroplasty (THA). The aim of the present paper was to analyse clinical and radiographic outcome, survival of the hip joint and risk factors of early conversion to THA in patients with PAO.
In the period 1999-2008, 93 patients (127 hips, median patient age 31, range 13-49 years) were operated on with PAO. Median follow-up was 7 (SD 2.1) years. Analyses of clinical and radiographic examinations, including WOMAC, were performed. Osteoarthritis was measured using Tönnis grade. Survival was assessed by the Kaplan-Meier method and predictors of conversion to THA were calculated using Cox regression analysis with THA as defined endpoint.
Centre-edge angle improved significantly with a mean of 8.7 (95% CI: 7.1; 10.3) preoperatively to a mean of 24.6 (95% CI: 22.6; 26.6) at follow-up. Likewise the acetabular roof obliquity angle improved significantly with a mean of 21.2 (95% CI: 19.7; 22.6) preoperatively to 8.7 (95% CI: 7.1; 10.4) at follow-up. Eleven out of 127 hips had conversion to THA. The 11.7 years cumulated hip joint survival rate was 85% (95% CI: 0.753; 0.945). Significant predictors of converting to THA were preoperative high grade of OA and postoperative high degree of acetabular roof obliquity angle. An improvement was found in Harris Hip Score pain score after receiving a PAO (p = 0.01).
Our results, with almost 12 years survival data, are comparable with the literature. PAO is considered as an effective treatment for young adults with painful hip dysplasia, especially when preoperative criteria for conversion to THA are highlighted.