Purpose: In surgery of C1-C2 fractures, standard navigation for screw placement based on preoperative image data was compared with intraoperative imaging guidance applying intraoperative computed tomography (iCT) with a special focus on accuracy of screw placement, workflow, and radiation exposure.
Methods: A single surgeon series of 16 consecutive patients with C1-C2 trauma was retrospectively analyzed. Seven patients were operated with standard navigation; preoperative image data were registered by a 20-point surface-matching process for each vertebra. Nine patients were operated with iCT guidance, allowing automatic navigation registration. Screw placement was examined and graded with either iCT or postoperative CT. Dose length product of CT and dose area products of fluoroscopy scans were assessed; effective radiation doses were estimated based on conversion factors. Radiation doses of intraoperative and postoperative X-ray and/or CT diagnostics for each group were summarized to compare the total effective doses.
Results: A total number of 72 screws were placed, 26 in the standard navigation group including 24 screws in C1 and C2, and 46 screws in the iCT group including 34 screws in C1 and C2. 15.38% (n = 4) of the C2 screws showed a grade 1 deviation and 3.8% (n = 1) a grade 2 deviation applying standard navigation. There was no misplacement of screws in the iCT group. Mean operating time in the standard navigation group was 186.57 min versus 157.11 min in the iCT group, while the mean summarized effective dose was 1.129 mSv in the standard navigation and 2.129 mSv in the iCT group.
Conclusion: iCT navigated surgery can lead to higher accuracy and shorter operating time compared to standard navigated operations. iCT is a safe and straightforward procedure allowing reduction in radiation exposure of the medical staff, while modified scan protocols resulted in a radiation exposure that is lower than in standard diagnostic neck CT.
Keywords: C2 fracture; Effective dose; Intraoperative computed tomography; Navigation registration; Radiation exposure; Screw placement; Spinal navigation.