Direct Vertebral Rotation: A New Technique of 3-D Deformity Correction with Segmental Pedicle Screw Fixation in Adolescent Idiopathic Scoliosis

Pedicle screw fixation with a rod rotation maneuver enables a powerful coronal and sagittal plane correction in scoliosis surgery, however the ability to achieve rotational correction of the vertebral bodies is still unclear.

Purpose: To compare a new technique of direct vertebral rotation (DVR) for improving rotational correction in scoliois versus the simple rod rotation (SRR) technique.

Materials and Methods: Thirty-eight AIS patients treated with segmental pedicle screw fixation were prospectively analyzed for rotational correction of scoliosis. The first group (n=17) was treated by rod rotation and DVR; the second group (n=21) was treated by a rod rotation maneuver alone. All patients had follow-up of minimum 2 years. Both groups, who had similar preoperative curve patterns, were evaluated for deformity correction, lower instrumented vertebral tilt (LIVT) and spinal balance. Apical vertebral rotation (AVR) was evaluated by CT scans (RAsac.). Surgical techniques of DVR were as follows: a precontoured rod at the correction side (concave in thoracic scoliosis) was inserted into segmental screws; a simple rod rotation (counterclockwise) was performed; and then screws were rotated to opposite direction (clockwise) with countertorque applied to the rod and then the screws were sequentially tightened. The SRR group was treated with a rod rotation only.

Results: In DVR group, 16.7o of AVR was corrected to 9.6o showing 42.5% correction, while in the SRR group 16.1o was corrected to only 15.7o. In DVR group, preoperative thoracic curve of 55o was corrected to 12o (79.6%) and the lumbar curve of 39o to 7o (80.5%). In SRR group, preoperative thoracic curve of 53o was corrected to 17o (68.9%) and the lumbar curve of 39o was corrected to 16o (62.2%). LIVT was corrected to 80.6% and 66.3%, respectively. There were significant differences in coronal curve, LIVT and rotational correction. Thoracic kyphosis was improved in both groups.

Conclusion: Segmental pedicle screw fixation with ‘direct vertebral rotation’ showed better rotational and coronal correction than a simple ‘rod rotation’ maneuver alone.