Comparing Safety and Efficacy of 3D Navigation vs. Fluoroscopy for Endoscopic Transforaminal Discectomy

Introduction: Endoscopic spine surgery traditionally uses fluoroscopic guidance for targeting and initial docking. In endoscopic transforaminal approaches, using fluoroscopy to target a small area is limited by coarse anatomic detail in cases with complex anatomy and a small margin of safety due to the exiting nerve root. To address this, 3D navigation provides real-time guidance with accurate image registration. In this study, we compare the safety and efficacy of fluoroscopic vs. navigated transforaminal discectomies.

Methods: A retrospective review was conducted of 27 patients who underwent a thoracic or lumbar transforaminal discectomy at a tertiary academic hospital from 2021-2023. Seven navigated cases were done, all with the Medtronic O-arm. Collected variables included pertinent medical history, surgical approach, and intraoperative complications. Patient radiation exposure was measured via cumulative air kerma (CAK), dose area product (DAP), and effective dose. Changes in validated pain metrics (VAS and ODI) were recorded at 1-month and > 3-month postop.

Results: Despite a higher effective dose (14.2 +/- 8.8 vs. 2.0 +/- 2.7 mSV; p< 0.001), navigation exposed patients to significantly less localized radiation compared to fluoroscopy which averaged 112.9 +/- 60.2 x-rays per case. This was shown through lower CAK (8.4 +/- 10.2 vs. 39.0 +/- 30.2 mGy; p=0.02) and DAP (1.9 +/- 2.3 vs. 8.7 +/- 6.4 Gy*cm2; p=0.02). Efficient targeting with navigation was also displayed with similar operative time (215.6 +/- 62.5 vs. 206.2 +/- 76.7 minutes, p=0.77) despite the time to bring in the O-arm and register the navigation system. Clinically, patients experienced significantly greater pain relief 1-month after navigation vs. fluoroscopy with improved VAS (-5.8 +/- 1.0 vs. -2.3 +/- 2.9; p=0.04) and ODI (- 15.3 +/- 3.1 vs. - 14.4 +/- 17.7; p=0.93). Although nonsignificant, relief was sustained at > 3 months (VAS - 4.5 +/- 3.5 vs. - 2.0 +/- 2.0; p=0.37).

Conclusion : Despite higher global radiation exposure, deterministic radiation effects and localized skin exposure are reduced with navigation. Intraoperatively, the benefit of expedited targeting with navigation offsets the upfront time needed to acquire the intraoperative CT and registration. Furthermore, navigation helps guide complete decompression and increase the chance of significant improvements in clinical outcomes.