Comparison of the Accuracy and Safety of Pedicle Screw Placement in Thoracic Spine Between 3D Printed Navigation Templates and Free Hand Technique

Relevance. Transpedicular spine fixation is considered the gold standard for posterior stabilization of the spine in various pathological processes. The most common implantation technique is the free hand method. But today the implantation with 3D printed individual navigation templates is gaining popularity. Purpose - to compare results of the pedicle screw placement in thoracic spine with application of 3D printed navigation templates by various design and free hand technique. Materials and Methods. Results of the three group of patients were analyzed based on postoperative CT. In group 1 (free hand) 112 screws were placed to 23 patients. In group 42 screws were placed to 11 patients using bilateral monosegmental navigation templates, in group 3 (13 patients, 42 screws) - using bilateral monosegmental templates with additional support on the spinous process. The safety of implantation was assessed and compared in all groups. In groups 2 and 3 the accuracy was also evaluated based on the difference between the planned and actual screws trajectory. Results. In group 1 safety grade 0 was registered in 66,96%, safety grade 1 in 18,75%, safety grade 2 - in 9,82%, safety grade 3 - in 4,46%. In group 2 grade 0 was registered in 85,71%, safety grade 1 - in 14,29%. In group 3 grade 0 - in 90,74%, safety grade 1 - in 9,26%. There were no cases of the cortical bone perforation for more than the half of the screw diameter in groups 2 and 3. The differences in the safety parameters are significant between free hand and both groups with application of the navigation templates. Assessment of the deviation hasn't revealed significant difference depending on the type of the templates. Conclusion. The use of the individual navigation templates for pedicular screws implantation in the thoracic spine is safer than the free hand method (p<0.05). Single-level bilateral matrices made by FDM technology from polylactide with support on a part of the dorsal vertebral structures make it possible to achieve the high implantation accuracy. Additional support on the spinous process does not lead to a statistically significant improvement in accuracy and safety indicators (p<0.05), while requiring extended dissection and resection of the ligamentous elements.