Augmented reality navigation for spinal pedicle screw instrumentation using intraoperative 3D imaging

Background context: Due to recent developments in augmented reality with head-mounted devices, holograms of a surgical plan can be displayed directly in the surgeon's field of view. To the best of our knowledge, three dimensional (3D) intraoperative fluoroscopy has not been explored for the use with holographic navigation by head-mounted devices in spine surgery.

Purpose: To evaluate the surgical accuracy of holographic pedicle screw navigation by head-mounted device using 3D intraoperative fluoroscopy.

Study design: In this experimental cadaver study, the accuracy of surgical navigation using a head-mounted device was compared with navigation with a state-of-the-art pose-tracking system.

Methods: Three lumbar cadaver spines were embedded in nontransparent agar gel, leaving only commonly visible anatomy in sight. Intraoperative registration of preoperative planning was achieved by 3D fluoroscopy and fiducial markers attached to lumbar vertebrae. Trackable custom-made drill sleeve guides enabled real-time navigation. In total, 20 K-wires were navigated into lumbar pedicles using AR-navigation, 10 K-wires by the state-of-the-art pose-tracking system. 3D models obtained from postexperimental CT scans were used to measure surgical accuracy. MF is the founder and shareholder of Incremed AG, a Balgrist University Hospital start-up focusing on the development of innovative techniques for surgical executions. The other authors declare no conflict of interest concerning the contents of this study. No external funding was received for this study.

Results: No significant difference in accuracy was measured between AR-navigated drillings and the gold standard with pose-tracking system with mean translational errors between entry points (3D vector distance; p=.85) of 3.4±1.6 mm compared with 3.2±2.0 mm, and mean angular errors between trajectories (3D angle; p=.30) of 4.3°±2.3° compared with 3.5°±1.4°.

Conclusions: In conclusion, holographic navigation by use of a head-mounted device achieve accuracy comparable to the gold standard of high-end pose-tracking systems.

Clinical significance: These promising results could result in a new way of surgical navigation with minimal infrastructural requirements but now have to be confirmed in clinical studies.