Radiologic Predictors for Clinical Improvement in PAO-A Perspective Study

The aim of this study was to evaluate the results of surgical treatment of developmental dysplasia of the hip (DDH) with periacetabular osteotomy (PAO) and determine the values of radiological parameters that would allow us to obtain an optimal clinical result. Radiological evaluation included determining the center-edge angle (CEA), medialization, distalization, femoral head coverage (FHC), and ilioischial angle as measured on a standardized AP radiograph of the hip joints. Clinical evaluation was based on the HHS, WOMAC, Merle d'Aubigne-Postel scales and Hip Lag Sign. The results of PAO presented decreased medialization (mean 3.4 mm), distalization (mean 3.5 mm), and ilioischial angle (mean 2.7°); improvement in femoral head bone cover; an increased CEA (mean 16.3°) and FHC (mean 15.2%); clinically increased HHS (mean 22 points) and M. Postel-d'Aubigne (mean 3.5 points) scores; and a decrease in WOMAC (mean 24%). HLS improved in 67% of patients after surgery. Qualification of patients with DDH for PAO should be based on the following values of three parameters: CEA < 26°, FHC < 75%, and ilioischial angle >85.9°. To achieve better clinical results, it is necessary to increase the average CEA value by 11° and the average FHC by 11% and reduce the average ilioischial angle by 3°.