Direct vertebral rotation: a new technique of three-dimensional deformity correction with segmental pedicle screw fixation in adolescent idiopathic scoliosis.

Abstract

A prospective study. To introduce a new technique, direct vertebral rotation, and to compare the surgical results of direct vertebral rotation with those of simple rod derotation. Pedicle screw fixation with a simple rod derotation maneuver enables a powerful coronal and sagittal plane correction in scoliosis surgery. However, the ability of achieving rotational correction is still unclear. Thirty-eight adolescent idiopathic scoliosis patients treated with segmental pedicle screw fixation were analyzed. The first group (n = 17) was treated by direct vertebral rotation; the second group (n = 21) was treated by simple rod derotation. All patients had a minimum follow-up of 2 years. Having similar preoperative curve patterns, both groups were evaluated for the deformity correction, lower instrumented vertebral tilt, and spinal balance. Apical vertebral rotation was evaluated by computed tomography scans. Surgical techniques of direct vertebral rotation were as follows: a precontoured rod was inserted into segmental screws on the concave side in thoracic scoliosis; a simple rod derotation was performed; and then the screws on the juxta-apical vertebrae, both on concave and convex sides, were rotated opposite direction to the rod derotation. Then, all the screws were sequentially tightened. In the direct vertebral rotation group, the average preoperative apical vertebral rotation of 16.7 degrees was corrected to 9.6 degrees, showing 42.5% correction, whereas in the simple rod derotation group, the correction was negligible from 16.1 degrees to 15.7 degrees (2.4%). In the direct vertebral rotation group, the average preoperative thoracic curve of 55 degrees was corrected to 12 degrees (79.6%), and the lumbar curve of 39 degrees was corrected to 7 degrees (80.5%). In the simple rod derotation group, the preoperative thoracic curve of 53 degrees was corrected to 17 degrees (68.9%), and the lumbar curve of 39 degrees was corrected to 16 degrees (62.2%). The average lower instrumented vertebral tilt correction was 80.6% and 66.3% in the directvertebral rotation and the simple rod derotation group, respectively. There were statistically significant differences in the coronal curve, lower instrumented vertebral tilt, and rotational correction (P < 0.05, Mann-Whitney U test). Thoracic kyphosis was improved in both groups. Segmental pedicle screw fixation with "direct vertebral rotation" showed better rotational and coronal correction than "simple rod derotation."