Three-dimensional computed tomography evaluation of bony birth canal morphologic deformity (small pelvic cavity) after dome pelvic osteotomy for developmental dysplasia of the hip

Objective: Using three-dimensional computed tomography, we investigated the morphologic deformity of the birth canal in patients with developmental dysplasia of the hip who underwent dome pelvic osteotomy. Study Design: Thirty-five normal subjects, 34 patients with developmental dysplasia of the hip who did not undergo dome pelvic osteotomy, and 21 patients with developmental dysplasia of the hip who underwent dome pelvic osteotomy were recruited for the study. We assessed the underlying pelvic deformities together with the postoperative pelvic morphologic changes (iatrogenic deformity). Results: Sagittal diameters of the pelvic contraction were longer, and transverse diameters of the pelvic inlet, expansion, and contraction were shorter in patients after dome pelvic osteotomy than in normal control subjects. Conclusion: Anthropoid-type pelvis (a long pelvic inlet diameter in the sagittal dimension while the corresponding measurement in the transverse dimension is short) was observed in as many as 90.5% of patients with developmental dysplasia of the hip after dome pelvic osteotomy. (Am J Obstet Gynecol 2002;187:1591-5.)