Hur JW, et al. - In this retrospective analysis, researchers assessed accuracy, effectiveness, and safety of intraoperative O-arm–based navigation system for the placement of C1 lateral mass screw (C1LMS) and C2 pedicle screws (C2PSs) in high cervical spine operations. A total of 48 patients with atlantoaxial instability were surgically treated using the image-guidance system between June 2009 and August 2016. Using the image-guidance system, a total of 182 screws, including 90 C1LMS and 92 C2PSs were inserted. According to findings, the use of image-guidance systems appears to be beneficial for high cervical instrumentation requiring a great deal of experience and steep learning curves. However, due to the close proximity to the spinal canal and surrounding vessels, the incidence of cortex violation does not completely disappear.