Intraoperative Computed Tomography Versus 3D C-Arm Imaging for Navigated Spinal Instrumentation

STUDY DESIGN: A prospective case-series study and a retrospective analysis of historical patients for comparison of data. OBJECTIVE: To compare accuracy and limitations of intraoperative computed tomography (iCT)- versus 3D C-arm-based spinal navigation for posterior pedicle screw implantation. SUMMARY OF BACKGROUND DATA: Despite the higher accuracy of navigated compared to non-navigated pedicle screw implantation, it remains a matter of debate whether the use of iCT imaging may further benefit navigated spinal instrumentation compared to more commonly used isocentric 3D C-arm imaging. METHODS: Between 2013 and 2016, 1527 pedicle screws were implanted in 260 patients with iCT (1219 screws) or 3D C-arm (308 screws)-based spinal navigation. Screw positioning was intraoperatively assessed by a second iCT or 3D C-arm (intraoperative accuracy). If necessary, immediate intraoperative screw revision was performed. Thereafter, a third iCT or 3D C-arm scan was performed to confirm repositioning (final accuracy). Clinical and patient data, intraoperative screw assessability, and accuracy rates were retrospectively reviewed and analyzed by an independent observer. RESULTS: Intraoperative CT permitted immediate intraoperative assessment of each implanted screw. In contrast, 39 of the screws visualized with 3D C-arm imaging were intraoperatively not clearly assessable. Regarding the overall precision, iCT and 3D C-arm navigation yielded a comparable intraoperative accuracy (iCT 94.7% vs 3D C-arm 89.4%) and immediate correction of misplaced screws was feasible with both modalities (final accuracy: iCT 95.4% vs 3D C-arm 91.6%). Regarding the region specific performance, however, iCT-based navigation yielded significantly higher final accuracy rates in the cervical (iCT 99.5% vs 3D C-arm 88.9%, P < 0.01) and thoracic (iCT 97.7% vs 3D C-arm 88.8%, P < 0.001) regions. CONCLUSION: Both iCT and 3D C-arm-based spinal navigation provides high pedicle screw accuracy rates. Immediate screw assessability and placement accuracy in the cervical-thoracic spine, however, appear to be limited with intraoperative 3D C-arm imaging alone. LEVEL OF EVIDENCE: 3.