Freehand Placement of the C1 Pedicle Screw Using Direct Visualization of the Pedicle Anatomy and Serial Dilatation.

Objective: We designed a method for inserting C1 pedicle screws using the direct visualization technique of the pedicle and serial dilatation technique to reduce complications and malposition of screw, and assessed the accuracy of this method.

Methods: Free-hand C1 pedicle screw insertion using the direct visualization technique of the pedicle and serial dilatation technique was performed on 5 consecutive patients with C1-2 instability at a single institute from March to December 2018. The method involved protecting the vertebral artery (VA) and C1 root using the Penfield No. 1, securing the entry point of the posterior arch screw and the pedicle was visible directly in Trendelenburg position. The hole at the entry point of the C1 posterior arch was serially dilated using a 2.5×3.0 mm drill bit, and the C1 pedicle screw was inserted with the free hand technique. We measured postoperative radiological parameters and recorded intraoperative complications, postoperative neurological deficits and the occurrence of occipital neuralgia. Postoperative computed tomography (CT) was performed to check screw malposition or construction failure.

Results: Of the 10 C1 pedicle screws on postoperative CT, 20% of screws (grade A) were in the ideal position while 80% of screws (grade B) occupied a safe position. Overall, 100% of screws were safe (grade A or B). There were no iatrogenic neurological deficits, VA injury.

Conclusion: Freehand placement of the C1 pedicle screw through the direct visualization technique of the pedicle and serial dilatation technique is safe and effective without intraoperative fluoroscopy guidance.