Abstract
Introduction
Application of transpedicular screws to obtain posterior spinal fusion in thoraco-lumbar spine has become standard in spinal surgery. However technique of screws insertion is demanding and not free of complications. Positioning is particularly challenging in pediatric patients with spinal deformity. Navigation systems based on intraoperatively obtained 3D image seem to be very promising solution to prevent or at least minimize screw misplacements. Although still lack of data confirming superiority of navigation above other techniques. The study was designed to assess the accuracy of transpedicular screws placement with O-arm and navigation in patients who underwent surgery for idiopathic scoliosis.
Material and Methods
451 screws in 27 patients were evaluated. All the screws were positioned by two surgeons (WU, WJ) with aid of navigation (Stealth Station, Medtronic) based on 3D image obtained during surgery (O-ARM, Medtronic). The accuracy was described separately for each screw based on postoperatively obtained CT scans. The assessment was made according to widely accepted grading system: grade 0 – no pedicle wall violation, grade 1 =< 2 mm perforation, grade 2 – wall perforation with half of the diameter of the screw outside of the pedicle (=< 4 mm), grade 3 complete perforation of the pedicle (>5 mm). The comparison of accuracy was made between adults (13 patients) and adolescents (14 patients).
Results
In the study authors reported overall accuracy of 96% correctly positioned pedicle screws (83% grade 0 and 13% grade 1). No grade 3 screws were reported. Statistical analysis confirmed decreased accuracy in upper thoracic level (82% of grade 0 and 1). No statistically significant differences in implant accuracy were observed between adults (96.2% of grade 0 and 1) and adolescents (95.3% of grade 0 and 1).
Conclusion
The application of navigation system is a safe method of pedicle screws introduction either in adults or adolescents. However the technique does not eliminate misplacement. Significant misplacement rate is still observed in upper thoracic spine.