# Concave Side of Proximal Thoracic Zone Vulnerable to Pedicle Screw Perforation in Adolescent Idiopathic Scoliosis Surgery: Comparative Analysis of Pre- and Intraoperative Computed Tomography Navigation

## TL;DR

This study shows that using intraoperative CT scans improves the accuracy of pedicle screw placement in scoliosis surgery, especially in the concave side of the upper thoracic region.

## Contribution

The study introduces the use of intraoperative CT navigation with a second 3D scan to enhance pedicle screw accuracy in adolescent idiopathic scoliosis surgery.

## Key findings

- Intraoperative CT navigation achieved higher screw accuracy (97%) compared to preoperative CT (95%).
- Grade D perforations were most common on the concave side of the proximal thoracic zone.
- Ten screws were reinserted in the intraoperative group based on second 3D scan findings.

## Abstract

Background: The aim of this study was to assess pedicle screw (PS) accuracy and identify perforation patterns using computed tomography (CT) navigation in adolescent idiopathic scoliosis (AIS) surgery. Methods: A total of 107 AIS patients were retrospectively reviewed. Preoperative CT navigation was used in 48 patients (853 screws), and intraoperative CT with a second 3D scan was used in 59 patients (1059 screws). Postoperative CT images were analyzed using the Rampersaud grading system. Results: Overall PS accuracy (grade A + B) was significantly higher in the intraoperative CT group than the preoperative group (97% vs. 95%, p = 0.008). In Lenke type 1 cases, accuracy was also higher in the intraoperative group (97.8% vs. 95.1%, p = 0.014). Grade D perforations were most frequent on the concave side of the proximal thoracic (PT) zone in both groups. Ten screws were re-inserted during surgery in the intraoperative group based on findings from the second 3D scan. Conclusions: The concave PT zone is a common site for PS misplacement. Intraoperative CT navigation with a second 3D scan enhances PS accuracy compared with preoperative CT navigation.