Abstract
The outcome of periacetabular osteotomy in dysplastic hips is dependent on the absence of preoperative osteoarthritis [OA]. The purpose of this study was to analyze whether Tonnis grading is a reliable predictor of OA in patients with hip dysplasia.
Thirty patients were identified who had undergone hip arthroscopy surgery to assess their suitability for periacetabular osteotomy. Radiographs were assessed for anterior centre edge angle, lateral centre edge angle, Tonnis angle and Tonnis grade for OA changes. The radiographic grading of OA was compared with arthroscopic findings.
Results
The average age at the time of arthroscopy was 34.97 [16 – 53yrs] (28 females). Tonnis grade did not correlate with arthroscopic findings (p=0.082). There was a trend for patients with a higher Tonnis grade to have more OA changes. Of the 30 patients, all 3 with grade 0 were fit for periacetabular osteotomy, while only 8 out of 24 with grade I, and 1 out of 3 with grade II were fit for periacetabular osteotomy.
This study reports that even when radiographic grading showed minimal OA changes, arthroscopy findings indicated significant OA changes. Hence radiographic grading is a poor indicator of OA and other diagnostic modality should be sought before proceeding with joint preserving surgery in this highly selected subgroup of dysplastic hips.
