Posterior Cervical Fixation: Accuracy and Safety of Free-Hand Inserted Screws.

Abstract

Background and objectives: Posterior fixation of the cervical spine (PFC) is commonly performed with rod-connected screws inserted in the vertebras. Because of the many sensitive structures located adjacent to the vertebras, computer-assisted navigation is often used with PFCs. We assessed safety and efficacy of free-hand placed PFCs.

Methods: We retrospectively identified all the patients in our institution between Januray 2006 and December 2016 who underwent a primary PFC for any indication. The postoperative images and medical records were evaluated for possible clinical failures, which was considered as a reoperation to cervical spine within 1 year after primary surgery for any reason, or a new screw-related adverse event including nerve root injury, spinal cord injury, or vertebral artery injury.

Results: In total, 332 patients and 1476 screws were included in the study. The evaluated screws were primarily pedicle and lateral mass screws. The rate of screw malposition was 12% (171/1476). The overall rate of clinical failure was 16% (52/332) and was significantly higher in patients with screw malposition than in those without malposition (24% vs 12%, P = .03). The rate of screw insertion-related clinical failure was 6.0% (20/332). The C7 pedicle seemed to be more prone to screw malposition than other locations (26/86, 30%).

Conclusion: Clinical failure after posterior cervical spine fixation occurs significantly more frequently in patients with screw malposition compared with those without malposition. The overall rate of screw insertion-related clinical failure was 6.0%. These findings suggest that improving screw placement accuracy may reduce the risk of complications.