Article
Intraoperative computed tomography versus iso-C 3D C-arm imaging for navigated spinal instrumentation
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Published: | June 9, 2017 |
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Objective: Recent meta-analysis have evidenced the superior accuracy of navigated spinal instrumentation compared to non-navigated techniques. However, the benefit of intraoperative computed tomography (iCT) compared to iso-C 3D C-arm-based navigation remains unclear. The aim of the present study was to report our experience and accuracy of navigated pedicle screw insertion with iCT or 3D C-arm-based spinal imaging in 254 consecutive patients.
Methods: After exposure and attachment of the navigation tracking device, a first iCT or 3D C-arm scan was performed with automatic patient/image co-registration and navigated screw insertion. Screw positioning was then intraoperatively assessed by a second iCT or 3D C-arm scan, based upon which the intraoperative accuracy was determined. In cases that required intraoperative screw revision, navigated repositioning was performed based on the second iCT or 3D C-arm scan. Thereafter, a third iCT or 3D C-arm scan was performed to confirm repositioning. In cases with 3D C-arm navigation, a postoperative CT scan was routinely performed, based upon which the final accuracy was determined compared to the final iCT scan. The general intraoperative screw placement assessability through iCT or 3D C-arm and the intraoperative and final accuracies were retrospectively reviewed and analyzed by an independent observer.
Results: Between 2013 and 2016, 1527 pedicle screws were implanted in 260 patients with either iCT (1219 screws) or 3D C-arm (308 screws) based spinal navigation and automatic patient/image co-registration. The indications for surgery were degenerative disease (61%), infectious disease (11%), tumors (13%) and trauma (15%). Direct intraoperative screw assessment with iCT was successfully accomplished for each screw in all patients. In contrast, 39 of the screws implanted with the help of 3D C-arm imaging were intraoperatively not clearly assessable due to hardware artifacts and limited image quality. Regarding the overall precision rates, 3D C-arm-based spinal navigation yielded a comparable accuracy to iCT-based imaging (intraoperative accuracy: iCT 94.7% vs. 3D C-arm 89.4%; final accuracy: iCT 95.4% vs. 3D C-arm 91.6%). Regarding the region specific intraoperative performance, however, iCT-based screw insertion yielded a significantly higher accuracy in the cervical (iCT 98.8% vs. 3D C-arm 84.6%, *p<0.0001) and thoracic (iCT 96.4% vs. 3D C-arm 83.3%, *p<0.0001) regions, whereas no difference was detected in lumbar-sacral instrumentations (iCT 91.8% vs. 3D C-arm 90.0%; p>0.05).
Conclusion: Both iCT and 3D C-arm-based spinal navigation solutions are able to provide high pedicle screw accuracy rates. However, immediate intraoperative screw placement assessability and screw placement accuracy in the cervical/thoracic spine appear to be limited with intraoperative 3D C-arm imaging alone.