Periacetabular osteotomy: preoperative radiographic predictors of outcome.

Periacetabular osteotomy is an extremely effective treatment for the spherical dysplastic hip without significant secondary osteoarthrosis. Yet, the reliability of the procedure in patients with some degree of secondary osteoarthritis, asphericity, or associated deformities remains undefined. The purpose of the current study was to analyze a group of patients treated by periacetabular osteotomy for dysplasia to identify preoperative factors that predict outcome. Ninety-five consecutive hips in 87 patients treated by periacetabular osteotomy were studied prospectively. Of this group, 52 hips in 49 patients were studied for a minimum of 2 years after surgery. Forty-six of the 52 procedures resulted in hips with stable or improved cartilage space intervals. By Tonnis category, there were 0 of 21 failures in Grade 1, four of 22 failures in Grade 2 (18%), one of eight failures in Grade 3 (12.5%), and one of one failure in Grade 4 hips. Five of the six failures had factors identifiable on preoperative radiographs that separated these hips from the successful reconstructions. This study shows that periacetabular osteotomy can reliably produce a stable hip, even in the presence of Grade 3 arthrosis, provided that the joint shows an improved cartilage space interval on the preoperative functional radiographs.