PEROPERATIVE 3-DIMENSIONAL CORRECTION OF IDIOPATHIC SCOLIOSIS WITH THE COTREL-DUBOUSSET PROCEDURE

Study Design. A peroperative measurement technique based on magnetic f ields was used to document the thoracic and lumbar vertebral changes i nduced by derotation of the concave rod during corrective surgery of i diopathic scoliotic deformities with Cotrel-Dubousset instrumentation. Objectives. Objective was to accurately document the immediate change s induced by the derotation maneuver to gain a better understanding of its effect on curve correction during a surgical procedure. Summary o f Background Data. Accurate peroperative documentation of these three- dimensional changes was very limited, and the exact contribution of th e derotation maneuver in the entire process of correction of a scoliot ic deformity was still poorly understood. Methods. A digitizer using m agnetic fields was used to record the three-dimensional orientation an d x, y, and z coordinates of the tip of every spinous process exposed at surgery before and after derotation of the concave rod in a group o f 22 female patients with idiopathic scoliosis. Results. A significant improvement of the scoliotic deformity was noted in the frontal plane , and improvement of thoracic hypokyphosis and lumbar hypolordosis in the sagittal plane was seen. Vertebral axial rotation remained unchang ed. Conclusions. The derotation maneuver is effective in achieving thr ee-dimensional correction of idiopathic scoliosis, but vertebral axial derotation is not an important component of this correction.