Evaluation of iliac morphology and innominate bone rotation in unilateral developmental dysplasia of the hip.

Three-dimensional assessments of unilateral developmental dysplasia of the hip (DDH) have not been performed yet. Using computed tomography scanning, this study aimed to determine the morphological and rotational abnormalities of the innominate bone in female patients with unilateral DDH. Patients with unilateral and bilateral DDH were compared with healthy patients. The distances between two points along each anatomical part of the pelvis and femur in the coronal plane were measured. The angles of each measurement line for the anterior pelvic plane (APP) and its perpendicular axis were investigated in the sagittal and horizontal planes. The distance between the acetabular centre and anterior inferior iliac spine was longer on both sides in the unilateral DDH group than in the bilateral DDH group. Values of several angles measured on the APP in the horizontal or sagittal plane differed between the unilateral DDH and bilateral healthy groups. The distance between the centres of the femoral head was longer in the unilateral DDH group than in the bilateral healthy group. The distance between the femoral head and middle of the pelvis was longer on the affected side than on the unaffected side in the unilateral DDH group. The iliac bone morphology was similar in both unilateral DDH and bilateral healthy groups; the rotation of the innominate bone was comparable to that in bilateral DDH. The femoral head on the affected side was shifted more laterally than that on the unaffected side in unilateral DDH.