Comparison of Shoulder Balance between Rod Derotation and Rod Derotation with Direct Vertebral Rotation in Double Thoracic Adolescent Idiopathic Scoliosis

Abstract

Introduction There is no report on the effect of DVR on the shoulder balance using segmental pedicle screw instrumentation in the treatment of double thoracic adolescent idiopathic scoliosis (AIS) with minimum 5-year follow-up. This study is to evaluate the shoulder balance resulting from the correction of double thoracic AIS comparing rod derotation (RD) with direct vertebral rotation (DVR) and RD only following pedicle screw instrumentations. Materials and Methods Double thoracic AIS patients ( 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 follow-up. Results In the RD with DVR group, the preoperative PT curve of 40.2 degrees improved to 17.9 degrees postoperatively and 19.9 degrees at last follow-up. In the RD group, the preoperative PT curve of 37.5 degrees improved to 22.4 degrees postoperatively and 23.2 degrees at last follow-up. In the RD with DVR group, the preoperative DT curve of 56.6 degrees improved to 16.1 degrees postoperatively and 16.7 degrees at last follow-up. In the RD group, the preoperative DT curve of 50.6 degrees improved to 17.8 degrees postoperatively and 18.2 degrees at last follow-up. In the RD with DVR group, the average preoperative SHD of 16.3 mm was improved to 7.2 mm postoperatively and was 7.0 mm at last follow-up. In the RD group, the average preoperative SHD of 15.1 mm was changed to 7.5 mm postoperatively and was 7.3 mm at last follow-up. Conclusion Shoulder balance was not significantly improved even with additional correction method of DVR using segmental pedicle screw instrumentation in double thoracic AIS. The PT curve was rigid and corrected less in both groups. Therefore, less correction of the DT curve effectively achieves better shoulder balance.