A Novel Intraoperative Technique to Determine Cranio-Caudal Angulation of Pedicle Screws in Thoracolumbar Spine? A Prospective Computerized Tomography–Based Analysis of 428 Screws

Background We report a novel technique of directing the sagittal profile of thoracic and lumbar pedicle screws using a freehand technique without the use of intraoperative monitoring.

Methods This is a prospective computerized tomography (CT)–based evaluation of pedicle screw insertion in the thoracic and lumbar spine of 64 patients operated upon for varied etiologies. All the patients were operated upon independently by 2 young surgeons with 1 year of spinal-fellowship experience. Intraoperatively, a right-angle retractor was positioned to determine the sagittal inclination of the pedicle screw. Postoperatively, sagittal CT scans were analyzed for the sagittal profile of the screw. The vertebral bodies were divided into 3 equidistant zones (A, B, and C) from the superior to inferior endplates, and the positions of the screw tips were noted.

Results There were 41 men and 23 women (mean age = 45.5 years). A total of 428 screws were inserted. There were 2 cases of superior pedicle wall violation in D1 and D5. The majority (96.97%) of the pedicle screws were inserted into zones A and B.

Conclusions We introduced a simple, accurate, and safe method of directing the sagittal inclination of the pedicle screw in the thoracic and lumbar spine without intraoperative image guidance.