gms | German Medical Science

Objective: Due to the complex anatomy of the craniocervical junction and the highly variable course of the vertebral artery, pedicle screw placement in this region remains a delicate procedure. With introduction of navigated screw placement (3D-fluroscopy/CT-based) an increase of accuracy has been promised. However, if a net benefit for patients’ safety regarding neurovascular complications compared to traditional methods results from this, has yet to be established. Therefore the purpose of this study was to assess the accuracy of pedicle screw placement in C2 using conventional fluoroscopy and intraoperative orientation via anatomic landmarks with the aim to determine the overall patient safety of this approach.

Methods: In this retrospective, single-center study the data of 24 patients with a range of conditions causing C2-instability who underwent dorsal stabilization between February 2013 and June 2017 was analyzed. Data was obtained by evaluating postoperative CT-scans regarding screw position in C2 using as reference for accuracy the grading system proposed by Bredow et al. (Table 1 [Tab. 1]). Patient outcome was determined based on medical reports (operative records, discharge papers, follow up reports).

Results: The records of 16 females and 8 males with a mean age of 68.25±14.4 years (range 27 to 84 years) were analyzed. Unstable pathologies included 10 fractures due to trauma, 7 due to tumor, 6 due to degeneration and 1 other. Correct screw positioning (Grade 1 and 2, pedicle wall perforation <2mm) was observed in 35 screws (76.1%) of 46 C2 pedicle screws (162 screws in total). No complications occurred during surgery, such as vertebral artery, nerve root, or spinal cord injury and only 1 case of screw misplacement in C2 which necessitated revision to ensure better long-term stability. A literature review of selected studies regarding navigated and non-navigated pedicle screw placement in the cervical spine showed a high accuracy rate of 96.8% vs. 87.1% (Table 2 [Tab. 2]). An OR of 1.11 indicates that navigated pedicle placement is 1.11 times more accurate than non-navigated.But regarding a CI of 95% it is not significant.

Conclusion: Our study suggests that using a conventional approach in dorsal stabilization of C2 appears to be sufficiently safe for pedicle screw placement (0% vascular or neurologic complications, 1 case of C2 revision) in C2 even though high accuracy was only determined at 76.1% compared to 96.80% in navigated screw placement (Table 2 [Tab. 2]).