Change in 2D and 3D femoral head coverage after curved periacetabular osteotomy

Abstract

Femoral head coverage in patients with hip dysplasia (DDH) is often quantified using 2D parameters, including the lateral center edge angle (LCEA) and anterior center edge angle (ACEA). However, only moderate correlations have been observed between the 2D coverage and 3D coverage. The purposes of this study were to: 1) quantify the change in 3D head coverage after curved periacetabular osteotomy (CPO), and 2) analyze the relationship between 2D and 3D head coverage preoperatively and postoperatively. Forty-three hips of 39 female cases (age: 37±10 years) who underwent CPO were analyzed. 2D coverage was quantified using the LCEA and ACEA from CT images. 3D coverage was quantified in the anterior, superior, posterior, inferior head regions. 3D measurements were performed both pre- and post-operatively and were correlated to the measurements of 2D coverage to study interactions. Preoperative 3D percent coverage in each head region was 17.8±6.7%, 36.2±7.7%, 57.6±10.2%, and 15.3±6.4% for the anterior, superior, posterior, and inferior region, respectively. Postoperatively, 3D coverage in the anterior and superior regions increased to 23.4% and 53.7%, respectively while a significant decrease was found for the posterior and inferior regions (all p<0.01). When 3D and 2D coverage was correlated, significant positive correlation was found between the 3D superior coverage and the LCEA both preoperatively (r=0.72, p<0.01) and postoperatively (r=0.67, p<0.01). However, no correlation was found between the 3D anterior coverage and the ACEA, which became significant in the postoperative period (r=0.69, p<0.01). Results indicate that preoperative anterior coverage for patients with DDH should be evaluated three-dimensionally.