We studied femoral head and neck deformity in Legg-Calvé-Perthes disease (LCPD) and epiphyseal dysplasia using three-dimensional computed tomography (3DCT) in 17 patients (22 hips). The deformed femoral head can be divided into two protions: (i) the portion that protrudes anterolaterally and inferiorly (false head), often blocking internal rotation (lower margin is radiographic “sagging rope” sign) and (ii) the posteromedial superior portion (true head), representing the original articulating femoral head. This remodeled segment is retroverted in relation to the anterolateral segment resulting in “functional retroversion,” which causes an externally rotated gait. This position also produces “functional coxa vara” measured by the relationship with the greater trochanter. These studies contradict previous reports of increased anteversion in LCPD and explain the paradox of supposed increased anteversion on radiograph in a child who walks with the limb externally rotated.
From the Department of Orthopaedic Surgery, Pusan National University Hospital, Pusan, Korea and the *Department of Orthopaedics, Children's Hospital and Health Center, University of California, San Diego, San Diego, California, U.S.A.
Study conducted at the Children's Hospital and Health Center, San Diego, California, U.S.A.
Address correspondence and reprint requests to Dr. D. R. Wenger at Department of Orthopaedics, Children's Hospital and Health Center, University of California, San Diego, 3030 Children's Way, Suite 410, San Diego, CA 92123, U.S.A.