Operative treatment of adolescent idiopathic scoliosis with posterior pedicle screw-only constructs minimum three-year follow-up of one hundred fourteen cases

Study Design. Preoperative review of a prospective study, single institution, consecutive series. Objective. To analyze the intermediate-term follow-up of consecutive adolescent idiopathic scoliosis (AIS) patients treated with pedicle screw constructs. Summary of Background Data. There have been no reports of the intermediate-term findings in North America following posterior spinal fusion with the use of pedicle screw-only constructs. Methods. One hundred and fourteen consecutive patients having a minimum 3-year follow-up (mean 4.8 ± 1.1; range, 3.0 -7.3 years) with AIS were evaluated. The average age at surgery was 14.9 ± 2.2 years. Radiographic measurements included preoperative (Preop), postoperative (PO), 2-year (2 years), and final follow-up (FFU). A chart review evaluated PFTs, Scoliosis Research Society scores, presence of thoracoplasty, Risser sign, Lenke classification, and complications. Results. The most frequent curve pattern was Lenke type 1 (45.6%), followed by type 3 (21.9%). The average main thoracic curve measured 59.2° ± 12.2 SD Preop, and corrected to 16.8° ± 9.9 PO (P < 0.0001). Sagittal thoracic alignment (T5-T12) decreased from 25.8° to 15.5° at FFU (P = 0.05). Nash-Moe grading for apical vertebral rotation (AVR) in the proximal thoracic curve decreased from 2.0 Preop to 1.1 at FFU (P < 0.0001), and AVR in the thoracolumbar/ lumbar spine decreased from 1.6 Preop to 1.1 at FFU (P < 0.0001). Importantly, the horizontalization of the subjacent disc measured -8.3° Preop which decreased to -0.9° PO (P < 0.001). PFT follow-up averaged 2.4 years with a 7.1% improvement in FVC (P = 0.004) and 8.8% in FEV1 (P < 0.0001). SRS scores averaged 83.0% at latest follow-up. Age, gender, Risser sign, or complications did not have a significant effect on outcomes. There were 2 cases of adding-on, 3 late onset infections, 1 with a single pseudarthrosis, but no neurologic complications. Conclusion. This is the largest (N =114), consecutive series of North American patients with AIS treated with pedicle screws having a minimum of 3-year follow-up. The average curve correction was 68% for the main thoracic, 50% for the proximal thoracic, and 66% for the thoracolumbar/lumbar curve at final follow-up.