The anterior center edge angle has limited ability to predict three-dimensional coverage of the femoral head in patients with developmental dysplasia of the hip undergoing curved periacetabular osteotomy

Introduction Femoral head coverage in patients with hip dysplasia (DDH) is typically quantified using 2D measurements of the lateral center edge angle (LCEA) and anterior center edge angle (ACEA). However, as the morphology of DDH is complex and varies between patients, 2D measurements may not predict the true 3D femoral head coverage. Herein, 2D and 3D coverage were quantified before and after curved periacetabular osteotomy (CPO) and their relationships were assessed. Materials and methods Forty-three hips that underwent CPO for DDH were analyzed. For 2D evaluation, LCEA was quantified from X-rays and CT images. The ACEA was measured from CT images (CT-ACEA) and digitally reconstructed radiographs generated from CT images (DRR-ACEA). Three-dimensional coverage was quantified from CT reconstructions of the hip and evaluated in the anterior, superior, posterior, and inferior regions of the femoral head. Two-dimensional measurements were correlated to 3D coverage to assess their relationships. Results The median preoperative 3D percent coverage was 17.7, 36.1, 56.1, and 14.6% for the anterior, superior, posterior, and inferior region, respectively. After CPO, all LCEAs and ACEAs increased significantly (all p