Purpose <p>This study aimed to evaluate the accuracy of pedicle screw placement using intraoperative computed tomography (CT)-based navigation in adolescent idiopathic scoliosis (AIS) surgery and to identify both patient- and screw-level risk factors associated with clinically significant screw deviation.</p> Methods <p>A total of 1,082 pedicle screws were placed in 67 consecutive AIS patients using intraoperative CT-guided navigation. Screw placement accuracy was graded according to the Gertzbein and Robbins classification system, with Grade C or D (≥ 2-mm cortical breach) defined as clinically significant deviation. Univariate and multivariate logistic regression analyses were performed to investigate risk factors for screw deviation, including morphometric parameters and surgical variables such as the distance from the navigation reference frame (RF).</p> Results <p>The overall rate of clinically significant screw deviation was 3.0%. Among patient-level factors, Lenke type 5 curves were associated with a significantly lower risk of deviation compared to type 1 curves (odds ratio [OR] 0.203, <i>P</i> = 0.026). At the screw level, the screw-to-pedicle diameter ratio was the strongest independent predictor of deviation (OR 1.607, <i>P</i> &lt; 0.001). Larger pedicle and screw diameters were associated with lower risk, while increased distance from the RF showed a trend toward higher deviation risk (<i>P</i> = 0.058).</p> Conclusion <p>Intraoperative CT-based navigation provides highly accurate pedicle screw placement in AIS surgery. Screw-to-pedicle diameter ratio and RF position represent critical determinants of deviation risk. Tailoring screw selection to pedicle anatomy and optimizing RF placement may improve safety and precision in spinal deformity correction.</p>