Employment of 3D rotational fluoroscopy for neuro-navigated screw placement in the cervical spine

Purpose: Pinpoint instrumentation is pivotal in cervical spine surgery in order to protect sensitive structures such as spinal cord or vertebral arteries. The aim of this study was to investigate the accuracy of neuro-navigated rotational fluoroscopy-guided screw positioning in the cervical spine employing a novel classification system. Methods: In procedures of dorsal cervical spine stabilization screw positions documented by rotational fluoroscopy were retrospectively evaluated. Accuracy of screw placement was analyzed using a new eight-grade scoring system with particular attention to the spinal canal, neuroforamina, and vertebral arteries. In addition, intra- and postoperative revision rates, as well as clinical and neurological outcome were evaluated. Results: One-hundred-forty-five patients with dorsal stabilization of the cervical spine were included. Of the 925 screws placed, 877 (94.8%) showed optimal positioning in the primary 3D image control. Differentiating between less and more than 50% of the screw diameter, 15 (1.6%) and 2 screws (0.2%) protruded into the transverse foramen. The pedicle or lateral mass were exceeded craniocaudally by 8 (≤50%: 0.9%) and 3 screws (>50%: 0.3%), respectively. Laterally, the pedicle or mass was exceeded substantially by 6 screws (0.6%). Medially, 8 (≤50%: 0.9%) vs. 6 screws (>50%: 0.6%) exceeded the wall of the pedicle or lateral mass. No patient underwent secondary surgery due to initial screw mispositioning. An improvement of the preoperatively indicated pain levels was documented in 87 of 114 patients (76.3%) with adequate follow-up. Conclusions