Untreated developmental hip dysplasia may result in pain, loss of function and is a common cause of osteoarthritis (OA). The periacetabular osteotomy (PAO) was developed to relieve symptoms and postpone further degeneration of the hip. We aimed to assess preoperative clinical and radiographic prognostic factors and evaluate survivorship of PAO after medium-term follow-up of 7.4 (2-15) years.
59 patients (69 hips) operated with a PAO through an anterior intrapelvic approach from 1999 to 2011 were retrospectively identified. The patients were evaluated radiographically and clinically with Harris Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index and 15D quality of life questionnaires. Survival analyses identified native hip joint survival predictors.
9 hips (9 patients) were converted to a total hip arthroplasty (THA). Of the 50 remaining patients (60 hips), 44 patients (54 hips) were examined at medium-term follow-up. 3 patients were lost to follow-up or declined participation and 3 were interviewed by telephone. Patient age at time of surgery was 32 (14-44) years. Survival analyses showed 84.3% (95% confidence interval [CI], 68.7-92.5%) survival of the native hip at 8 years follow-up (number at risk 32) (worst case scenario 80% survival at 8 years, 95% CI, 63.9-89.2%, number at risk 32). Cox regression with presence of preoperative OA (Tönnis ⩾1), showed a crude hazard ratio for conversion to THA with preoperative OA of 13.73, 
Periacetabular osteotomy through the anterior intrapelvic approach can be performed safely and with satisfactory results at medium-term follow-up. The presence of preoperative incipient OA (Tönnis ⩾1) is the most important predictor for poor hip joint survival.