Posterior First and Second Cervical Vertebrae Fusion by Screw Fixation Technique using the Modern Pre-fabricated Template Method on Cadaver Samples

Introduction: C1 lateral mass and C2 pedicular screws insertion are used for C1-C2 posterior fusion. Fluoroscopy Guided technique is routinely used for screw placement but it is associated with risk of injury to spinal cord and vertebral artery. 3D printing has developed rapidly in the fields of medicine. It is helpful in improving precise treatment and used for instrumentation in spine. We want to evaluate the accuracy of C1 lateral mass screws and C2 pedicle screws insertion by Pre-Fabricated Template made by three-dimensional (3D) printing.

Materials and methods: Five cervical samples were obtained from cadavers. Based on fine-cut CT scan 3D-images reconstructed and the path of the screws designed by special software. A template produced by 3D-printer from 3D images. After printing the templates, they were fixed on the relevant vertebra in the operation room and based on the template path, C1 lateral mass screw and C2 pedicular screws were inserted. Placement of the screws was evaluated using CT scans post-operatively.

Results: A total of 14 screws were inserted by above-mentioned method. After evaluation with CT scans none of the screws were entered in the spinal canal. Two screws had vertebral artery canal perforation with less than 50% breach. Violation was judged as noncritical and would probably not have resulted in injury to vertebral artery.

Conclusions: The accuracy of C1 lateral mass screw and C2 pedicle screw insertion is acceptable with pre-fabricated template and can provide a useful aid for screw placement.