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

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.