Comparison of Proximal Fusion to T1 or T2 in Double Thoracic Adolescent Idiopathic Scoliosis

Purpose : To assess the results of double thoracic fusion using pedicle screw instrumentation fused proximally to T1 or T2 in patients with double thoracic adolescent idiopathic scoliosis (AIS). Materials and Methods : Forty patients with double thoracic AIS were analyzed retrospectively after a minimum follow-up of 2 years. The patients were divided into two groups according to the proximal fusion level: the T1 group (n=26) was fused to T1 and the T2 group (n=14) was fused to T2. Results : There were no significant differences in the preoperative curve characteristics between the two groups. In the T1 group, the preoperative upper curve magnitude of 38±7˚ and apical vertebral translation (AVT) of 8±6 mm were corrected to 17±7˚ (54% correction) and 4±3 mm (3 mm correction) at the final follow-up, respectively. In the T2 group, the preoperative upper curve magnitude of 37±5˚ and the AVT of 7±4 mm were corrected to 22±6˚ (42% correction) and 6±3 mm (1 mm correction) at the final follow-up, respectively. There was no difference in the correction of lower thoracic curve, sagittal alignment and balance between the two groups. There was a significantly better correction in the upper thoracic curve and T1 tilting in the T1 group than the the T2 group. Conclusion : In double thoracic AIS, fusions to T1 and T2 produce satisfactory results. However, fusion to T1 is recommended for a better correction of the upper curve and T1 tilting.