Analysis of femoral head coverage in patients with hip dysplasia following peri-acetabular osteotomy using a novel CT-based technique

摘要

Introduction: Assessing coverage of the femoral head is a crucial element in acetabular surgery for hip dysplasia. Radiographic indices give rather limited information. Moreover, mathematical equations for calculating coverage based onplainradiographs are cumbersome, complex and involvemany assumptions. Computerised tomography has proven to be a more accurate, practical and informative way of analysing hip geometry. Klaue et al first used a computer-assisted model to indirectly derive representations of femoral head coverage. Jansen et al then described a CT-based method for measuring centre edge angle (CEA) of Wiberg at 10 rotational increments. Later Haddad et al used that method to look at dysplastic hips pre- and post-acetabular osteotomy. We present a novel CT-based method that automatically gives an image of the head with the covered area precisely represented. We used this technique to accurately measure femoral head coverage (FHC), CEA and acetabular index of the weight bearing zone (AI) in a series of normal hips and in a prospective study of patients with hip dysplasia undergoing peri-acetabular osteotomy.