Intermediate to Long-Term Results Following the Bernese Periacetabular Osteotomy and Predictors of Clinical Outcome

BACKGROUND: The Bernese periacetabular osteotomy is a commonly used non-arthroplasty option to treat developmental hip dysplasia in symptomatic younger patients. Predicting which hips will remain preserved and which hips will go on to require arthroplasty following periacetabular osteotomy is a major challenge. In the present study, we assessed the intermediate to long-term results following periacetabular osteotomy to demonstrate the clinical outcomes for patients with varying amounts of dysplasia and arthritis. From these results, a probability-of-failure analysis was conducted to predict the likelihood of hip preservation and to improve surgical decision-making. METHODS: Of the 189 hips (in 157 patients) that were treated with periacetabular osteotomy by a single surgeon from May 1991 to September 1998, thirty-one had diagnoses other than developmental hip dysplasia and twenty-three were lost to follow-up. The remaining 135 hips (in 109 patients) were retrospectively reviewed at an average of nine years. Hips were evaluated with use of the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index postoperatively as well as with radiographs that were made preoperatively and at one and more than five years postoperatively. Osteotomy failure was defined as a pain score of >or=10 or the need for total hip arthroplasty. RESULTS: One hundred and two hips (76%) remained preserved at an average of nine years, with an average Western Ontario and McMaster Universities pain score of 2.4 of 20. Thirty-three hips (24%) met the failure criteria: seventeen underwent arthroplasty at an average of 6.1 years after the osteotomy, and sixteen had a postoperative pain score of >or=10. Kaplan-Meier analysis with arthroplasty as the end point revealed a survival rate of 96% (95% confidence interval, 93% to 99%) at five years and 84% (95% confidence interval, 77% to 90%) at ten years. Complications occurred in twenty hips. Fifteen hips (11%) were treated with a subsequent arthroscopy because of chondral and/or labral lesions at an average of 6.8 years after the osteotomy. Two independent predictors of failure (defined as arthroplasty or a high pain score) were identified: (1) an age of more than thirty-five years and (2) poor or fair preoperative joint congruency. The probability of failure requiring arthroplasty was 14% for hips with no predictors of failure, 36% for those with one predictor (either an age of more than thirty-five years or poor or fair joint congruency), and 95% for those with both predictors. CONCLUSIONS: The Bernese periacetabular osteotomy can be effective for the treatment of painful hip dysplasia, but complications may be expected in as many as 15% of cases. The ideal candidate is the patient who is less than thirty-five years of age and who has good or excellent hip joint congruency.