COMPARISON BETWEEN PREOPERATIVE AND POSTOPERATIVE 3-DIMENSIONAL RECONSTRUCTIONS OF IDIOPATHIC SCOLIOSIS WITH THE COTREL-DUBOUSSET PROCEDURE

Study Design. Pre- and postoperative three-dimensional reconstructions of the spine and rib cage were done and compared in a group of adoles cents with idiopathic scoliosis. Objective. Changes in the shape of th e thoracic spine and rib cage induced by the Cotrel-Dubousset instrume ntation and procedure were documented. Summary of Background Data. Alt hough many authors have reported significant curve improvement in the frontal plane, attempts to document derotation of the spine have shown only limited correction of apical vertebral rotation. Methods. Three- dimensional reconstructions were obtained pre- and postoperatively usi ng a stereoradiographic technique in a group of 37 adolescents with id iopathic scoliosis. Several geometrical indices of the spine and rib c age were compared using Student t tests. Results. The curve correction averaged 50% in the frontal plane and 24% in the plane of maximum cur vature, while normal thoracic kyphosis was maintained in the sagittal plane. The orientation of the plane of maximum curvature was shifted v ery significantly toward the sagittal plane, indicating en bloc moveme nt of the thoracic spine and three-dimensional correction of the defor mity. A small but significant change in vertebral axial rotation and r ib hump was found and improvement in the overall orientation of the ri bs was documented. Conclusions. The Cotrel-Dubousset instrumentation a nd procedure are effective in producing three-dimensional improvement of the thoracic spine by en bloc relocation of the instrumented spine rather than by vertebral axial derotation.