Augmented reality-navigated pedicle screw placement: a cadaveric pilot study

Purpose Augmented reality (AR) is an emerging technology with great potential for surgical navigation through its ability to provide 3D holographic projection of otherwise hidden anatomical information. This pilot cadaver study investigated the feasibility and accuracy of one of the first holographic navigation techniques for lumbar pedicle screw placement. Methods Lumbar computer tomography scans (CT) of two cadaver specimens and their reconstructed 3D models were used for pedicle screw trajectory planning. Planned trajectories and 3D models were subsequently uploaded to an AR head-mounted device. Randomly, k-wires were placed either into the left or the right pedicle of a vertebra (L1-5) with or without AR-navigation (by holographic projection of the planned trajectory). CT-scans were subsequently performed to assess accuracy of both techniques. Results A total of 18 k-wires could be placed (8 navigated, 10 free hand) by two experienced spine surgeons. In two vertebrae, the AR-navigation was aborted because the registration of the preoperative plan with the intraoperative anatomy was imprecise due to a technical failure. The average differences of the screw entry points between planning and execution were 4.74 +/- 2.37 mm in the freehand technique and 5.99 +/- 3.60 mm in the AR-navigated technique (p = 0.39). The average deviation from the planned trajectories was 11.21 degrees +/- 7.64 degrees in the freehand technique and 5.88 degrees +/- 3.69 degrees in the AR-navigated technique (p = 0.09). Conclusion This pilot study demonstrates improved angular precision in one of the first AR-navigated pedicle screw placement studies worldwide. Technical shortcomings need to be eliminated before potential clinical applications.