Objectives: To evaluate the early coronal and sagittal correction of main thoracic adolescent idiopathic scoliosis using pedicle screw instrumentation and to determine whether implant density influences correction.

Methods and results: 49 consecutive patients with Lenke I main thoracic adolescent idiopathic scoliosis underwent single stage posterior correction and instrumented spinal fusion with pedicle screw fixation between 2006 and 2008. All surgeries were performed in a single institution by a single surgeon using identical surgical technique and type of instrumentation. Pre- and postoperative radiographs were analyzed. The pre-operative main thoracic curve of 60.0 ± 13.4° was corrected to 17.4 ± 6.9° (69.9% correction) on the post-operative radiographs. The pre-operative thoracic kyphosis of 20.0 ± 10.2° decreased to 11.6 ± 4.9° post-operatively. There was a significant correlation between decrease in sagittal kyphosis and magnitude of coronal Cobb angle correction (P = 0.002). There was no correlation between implant density and magnitude of coronal or sagittal curve correction, with and without curve flexibility taken into consideration.

Conclusions: Pedicle screw constructs provided excellent coronal correction of thoracic idiopathic scoliosis, however this was at the expense of sagittal contour. Decrease in sagittal kyphosis correlated with magnitude of coronal correction. Bilateral segmental pedicle screw fixation did not improve curve correction compared with unilateral or alternate segmental fixation.

Ethics approval: None required. Caldicott and Data Protection Approval No. 661.

Interest Statement: None.