Accuracy, safety, and functional outcomes of O-arm navigation-guided posterior cervical spine fixation: An ambispective cohort of 147 screws

Background: Posterior cervical fixation with lateral mass screws (LMSs) and cervical pedicle screws (CPS) is well established, but free-hand and fluoroscopy-guided techniques remain limited by accuracy and safety concerns. Intraoperative O-arm navigation provides real-time three-dimensional (3D) imaging and may improve precision while reducing complications. This study evaluates screw accuracy, safety, operative parameters, and functional outcomes using O-arm-guided posterior cervical fixation. Methods: This ambispective observational cohort analyzed 147 screws placed under O-arm-based 3D navigation. Primary outcome was screw accuracy graded on intraoperative O-arm scans; secondary outcomes included breach rates, complications, operative metrics, blood loss, radiation dose, and functional scores (Visual Analog Scale [VAS], modified Japanese Orthopaedic Association [mJOA], Nurick, American Spinal Injury Association) assessed over 1 year. Results: Overall screw accuracy was 99.3%, with 146 screws fully contained and one C2 CPS showing a high-grade breach (0.7%) without neurological deficit. No wound infections, hardware failures, or reoperations were recorded. Functional outcomes improved significantly: mean VAS decreased from 5.5 to 1.8, mJOA increased from 12.6 to 14.3, and Nurick grade improved from 3.1 to 2.4 at 12 months (all P < 0.01). Average operative time was 236 min, blood loss 350 mL, and mean radiation dose 1145 mGy•cm. Conclusion: In this observational cohort of 147 screws for posterior cervical fixation with O-arm navigation, we achieved a screw placement accuracy of 99.3% with only one high-grade breach and no neurological deficits or reoperations