The use of orthogonal plain radiographs in determining the position of thoracic pedicle screws: a cadaveric study.

backgroundPlain radiography remains the standard for intra- and post-operative assessment of pedicle screw placement in spine surgery. While newer technologies like intraoperative CT and navigation have been introduced, they do not consistently improve thoracic pedicle screw accuracy. The aim of this study was to evaluate the accuracy of anteroposterior (AP) alone versus orthogonal (AP and lateral) radiographs in assessing thoracic pedicle screw position across different observer experience levels and to determine the reliability of traditional fluoroscopy as compared to newer modalities. MATERIALS AND

methods23 disarticulated adult thoracic vertebrae were instrumented with pedicle screws placed either intra-osseous or with deliberate medial or lateral cortical violations. True AP and lateral radiographs were independently reviewed by two spine surgeons, two trainees, and two radiologists, blinded to actual screw positions. They categorized screws as "inside pedicle," "out laterally," "out medially," or "unsure." Assessments were compared to confirmed positions using axial views and direct visualization.

resultsOrthogonal radiographs had 74.3% accuracy in screw position assessment and 77.3% accuracy in detecting cortical breaches, outperforming AP-only views. Lateral breaches were most easily identified, while intra-osseous placement was most often misclassified. Notably, 20.5% of medial breaches were incorrectly identified as intra-osseous, most commonly by radiologists. Surgeons were more accurate and cautious than both trainees and radiologists in reporting screw placement.

conclusionOrthogonal radiography remains a viable tool for thoracic pedicle screw assessment if used judiciously. Surgical experience enhances interpretation accuracy, particularly in identifying medial breaches, which carry a notable risk of being reported as intra-osseous.