gms | German Medical Science

Objective: Spinal dorsal instrumentation is an established treatment option for a range of spinal disorders In combination with navigation, intraoperative fluoroscopy reduces the risk of incorrectly placing screws. This study aimed to evaluate the efficacy and validity of fluoroscopy (3D rotation of C-arm vs. O-arm) for placing screws and verifying the placement during spinal surgery as compared with postoperative control CT scans.

Methods: In this retrospective single-center study, 240 patients were included between July 2017 and April 2020. Intraoperative images were acquired using a Siemens-Arcadis Orbic 3D C-arm with a dedicated navigation system (Brainlab) or using O-arm (Medtronic) with a dedicated navigation system (S7 StealthStation). The final position of the screws was verified by a postoperative CT scan. Finally, we compared mismatches between intraoperative and postoperative CT imaging results using Rampersaud-grade (A-D).

Results: A total of 1614 screws were included in the evaluation: 94 patients in the C-arm group (cAG) and 146 in the O-arm group (oAG). After implantations, a second scan was performed intraoperatively. In cAG, 3% (n=20) of the screws had to be replaced directly due to inadequate positioning with median or lateral breaches, and 3.5 % of screws in oAG (n=35). An A-score was achieved for 85.7% in the cAG and 87.4% in the oAG. A B-score was found in 11.5% in the cAG and 11.9% in the oAG. In the cAG, a C-score was achieved for 2.5% and in oAG for 0.7%. For 0.3% of the screws a D-score was found in cAG and for none in oAG.

Conclusion: The data of our study shows that placement of screws using intraoperative imaging in combination with navigation tool is accurate. Furthermore, navigation coupled with the O-arm had significant advantages in accuracy over navigation with 3D C-arm fluoroscopy. However, both systems offer a high level of accuracy.