Comparison of surgical outcomes of lenke type 1 idiopathic scoliosis: vertebral coplanar alignment versus derotation technique.

STUDY DESIGN: Prospective clinical study.

OBJECTIVE: To compare the surgical outcomes of vertebral coplanar alignment (VCA) technique against the derotation maneuver with segmental pedicle screw instrumentation in patients with Lenke type 1 idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA: Nowadays the majority of scoliosis correction begins with rod rotation and translation from the concave side, which bears potential neurovascular risks. The technique of VCA was introduced by Vallespir with the intention of correcting rotation and translation and restoring the normal sagittal profile of thoracic scoliosis simultaneously.

METHODS: The fusion levels were decided according to the Lenke criteria. In group A (24 cases), the VCA technique was used. The pedicle screws were inserted at each vertebral level on the convex side and at every other level on the concave side, an extended coplanar tube was secured in line with screw axis to each pedicle screw. Two rigid bars were inserted through the top of the slotted tube. The first rod was kept in this position, whereas the second bar was gently driven down through the slotted tube toward the bottom end. This causes the pedicle screws to align in the sagittal plane, and hence, correct both translation and rotation. The thoracic kyphosis was restored with spacers, which separate the coplanar tubes apart. The derotation maneuver was applied in group B (24 cases). Multiple clinical and radiographic parameters were evaluated and compared.

RESULTS: The preoperative data were similar between the 2 groups in terms of age, sex, Risser sign, and curve magnitude. In group A, the coronal Cobb angle was corrected from an average of 58 to 16 degrees with a correction rate of 71.8%, and the thoracic kyphosis was restored from an average of 18 to 28 degrees. In group B, the coronal Cobb angle was reduced from 55 to 17 degrees with a correction rate of 68.4%, and the thoracic kyphosis was increased from an average of 15 to 18 degrees. Patients were followed for an average of 17 months (14 to 20 mo) with both groups showing no significant loss of correction. There were no vascular or neurological complications related to pedicle screw insertion or scoliosis correction. Two screws pullout occurred on the concave side in group B. There was 1 case of hemothorax related to a thoracoplasty procedure in group B. No pseudarthrosis occurred during follow-up in both the groups.

CONCLUSIONS: In treating thoracic scoliosis, the VCA technique could achieve as good correction and clinical outcome as the derotation technique. The advantage lies in its superior renormalization effect of thoracic kyphosis compared with the derotation technique from the concave side.