Background: Surgical treatment of the adolescent idiopathic scoliosis consists of a three-dimensional correction, involving correction of the vertebral rotation in axial plane, correction of the coronal and sagittal imbalance. Previously, most studies have considered coronal Cobb angle correction as the main objective. Currently, it is admitted that the restoration of sagittal alignment remains also a primary goal. Bending rods intraoperatively can be complicated, leading to complications such as rod notching or sagittal imbalance.

Objective: The aim of this study is to analyze the restoration of sagittal balance postoperatively in AIS using patient-specific rods and compare the sagittal alignment obtained at last follow-up with the preoperative planning.

Methods: In this study, we analyzed the radiological outcomes of 53 AIS patients treated by correction fusion surgery using patient-specific rods between 2019 and 2023. Rods bending was planned by the surgeon, based on spinopelvic parameters from the patient, according to the principles described by Kariman Abelin Genevois (KAG). Demographic data, relevant radiological parameters and classifications were carried out early preoperatively, immediate post-op, 6 weeks post-op, at 6 months, at two years and at last follow up.

Results: Most of the predictions of post-operative changes in sagittal parameters were inaccurate, with only three parameters (thoracic kyphosis (TK), pelvic incidence (PI), and C7 plumb line to S1 (SVA)) showing no significant differences between the predicted values and the early postoperative values. However, thoracic hypokyphosis was corrected in 14 out of 17 (82.3%) patients with preoperative hypokyphosis (< 20°). Out of the 53 patients, only 4 (7.5%) patients had a hypokyphosis postoperatively. Adjusted multivariate logistic regression didn't show any predictive factor for a poor correction of sagittal alignment correction.

Conclusions: Patient-specific rods are helpful for the surgeon to restore optimal sagittal alignment and the preoperative predictions correspond to the values obtained at last follow-up. Methods: Level IV.