How to Improve Shoulder Balance in the Surgical Correction of Double Thoracic Adolescent Idiopathic Scoliosis

Study Design. A retrospective comparative study. Objective. To evaluate the shoulder balance resulting from the correction of double thoracic adolescent idiopathic scoliosis (AIS) comparing rod derotation (RD) with direct vertebral rotation (DVR) and RD only after pedicle screw instrumentations. Summary of Background Data. This is the first report on the effect of DVR on the shoulder balance using segmental pedicle screw instrumentation in the treatment of double thoracic AIS with minimum 5-year follow-up. Methods. Patients with double thoracic AIS (n = 57) were treated by fusing both thoracic curves with RD and DVR (n = 35), or RD (n = 22) methods and retrospectively studied with a minimum 5 years of follow-up. Results. In the RD with DVR group, the preoperative proximal thoracic curve of 40.2 degrees improved to 17.9 degrees postoperatively and 19.9 degrees at the last follow-up. In the RD group, the preoperative proximal thoracic curve of 37.5 degrees improved to 22.4 degrees postoperatively and 23.2 degrees at the last follow-up. In the RD with DVR group, the preoperative distal thoracic curve of 56.6 degrees improved to 16.1 degrees postoperatively and 16.7 degrees at the last follow-up. In the RD group, the preoperative distal thoracic curve of 50.6 degrees improved to 17.8 degrees postoperatively and 18.2 degrees at the last follow-up. In the RD with DVR group, the average preoperative shoulder height difference of 16.3 mm had improved to 7.2 mm postoperatively and was 7.0 mm at the last follow-up. In the RD group, the average preoperative shoulder height difference of 15.1 mm had changed to 7.5 mm postoperatively and was 7.3 mm at the last follow-up. Conclusion. Shoulder balance had not significantly improved even with additional correction method of DVR using segmental pedicle screw instrumentation in double thoracic AIS. The proximal thoracic curve was rigid and corrected less in both groups. Therefore, less correction of the distal thoracic curve effectively achieves better shoulder balance.