gms | German Medical Science

Objective: Sophisticated intraoperative imaging technologies such as intraoperative CT (iCT), cone-beam CT (CBCT) or robotic CBCT (rCBCT) remain expensive and their benefits and limitations in combination with spinal navigation have not yet been characterized in a comparative fashion. Therefore, the purpose of this study was to assess workflow, handling, accuracy and image quality of iCT-, CBCT- and rCBCT-based spinal navigation.

Methods: Between 2014 and 2018, 2.536 pedicle screws were implanted in 445 patients with iCT- (1219), CBCT- (638) or rCBCT- (679) based spinal navigation and automatic patient/image co-registration. After attachment of the navigation tracking device to a spinous process or the iliac crest, an iCT / CBCT / rCBCT registration scan was performed to allow navigated, guide-wire assisted pedicle screw implantation. Screw positioning was assessed intraoperatively by a second iCT / CBCT / rCBCT scan and immediate repositioning was performed, if needed. Clinical, demographic and radiographic patient data was analysed by two independent observers.

Results: The indications for surgery were degenerative disease (64%), trauma (15%), tumour (11%), and infectious disease (10%). The median length of instrumentation was 3 (1-16) segments for iCT, 1 (1-16) for CBCT and 2 (1-10) for rCBCT (*p<0.0001 for CBCT vs. iCT and rCBCT). All imaging modalities permitted direct intraoperative assessment of each implanted screw with image quality benefits of iCT in obese patients and in the cervico-thoracic region. Overall, screw accuracy was higher in iCT- (95.4%) and CBCT- (97.5%) than in rCBCT- (92.6%; *p<0.05 vs. iCT and CBCT) based spinal navigation. Apart from image quality, the main benefit of iCT was the large gantry and scan area, which facilitated pelvic instrumentation and instrumentation > 5 segments. In contrast, the main benefit of CBCT and rCBCT was the independent usability by a qualified surgeon with a user interface in rCBCT technology that allows completely independent operation, which remains particularly useful when radiological assistance or specialized OR personnel is not readily available.

Conclusion: iCT, CBCT and rCBCT provide high pedicle screw accuracy and excellent image quality for reliable intraoperative screw assessment with the option of immediate revision, if needed. Overall, the individual preference remains determined by workflow, handling, patient characteristics and technical differences.