Augmented Reality Spine Surgery Navigation

Abstract

Study Design. Collectively, seven cadavers were instrumented with 124 thoracolumbar pedicle screws using VisAR augmented reality/guidance. Sixty-five screws were inserted into four donors using open dissection spine surgery. Fifty-nine screws were positioned in three donors with a minimally invasive spine surgery (MISS) procedure. For both open and MISS, VisAR was used exclusively for pedicle screw navigation.Objective. The objective of this study was to determine the accuracy of pedicle screw placement using VisAR for open spine and MISS procedures. Summary of Background Data. Pedicle screw placement can be challenging depending on anatomical location and a surgeon's experience. AR may minimize fluoroscopy use and speed screw insertion. Methods. Prior to computed tomography (CT) a series of four image visible April Tag optical fiducials were attached to the backs' of the donors. Resulting images were used preoperatively for planned virtual pedicle screw pathways including entry point, trajectory, and depth. The study link was encrypted on a quick response (QR) code, printed, and viewed in the operating room (OR) by the surgeon using VisAR (HoloLens 2 headset). Viewing the code wirelessly uploads and launches the study, converting the DICOM data to holographic images which register to the fiducials on the donor's back. The annotated pathways for each pedicle were called up by voice command and the surgeon positioned each screw by aligning with the virtual guidance hologram. Results. Overall, 124 pedicle screws were inserted with VisAR navigation with 96% accuracy (Gertzbein-Robbins grades A and B). The combined angle of error was 2.48 and the distance error was 1.9 mm. Conclusion. Augmented reality is a highly accurate, emerging technology for navigating both open and minimally invasive spine surgery techniques with off-the-shelf headset hardware.

Augmented reality for minimally invasive spinal surgery

“…This allows the surgeon to see a 3D image of the patient's spine with the skin intact and two-dimensional (2D) computed tomography (CT) images of the instruments' path and trajectory while looking directly at the surgical field (36) (Figure 3). Currently, wearable devices, such as HMD, have been commonly used to display AR views for ease and speed and to accomplish feasibility, accuracy, and safety in workflows from open cases to MISS (14,19). Current platforms include key features such as reducing attention shift from the surgical field to monitors, line-ofsight interruption, and cumulative exposure to ionizing radiation.…”

“…Studies have reported that Xvision by Augmedics has pedicle screw accuracies greater than at least 97.7% (40). Felix et al compared pedicle screw accuracies between open and MISS procedures as both were guided by the AR system, VisAR (14). A total of 124 pedicle screws were inserted with VisAR navigation with 96% accuracy (Gertzbein-Robbins grades A and B), reporting that AR is an emerging technology can be highly accurate for both surgeries (14).…”

“…During procedures, live computer navigation is interrupted by an obstacle that blocks the visualization of tracking markers by a remote tracking camera, resulting in the loss of live navigation until the obstruction is resolved (19). This is a common limitation as it may increase the operative time and decrease the accuracy (14). To combat such barriers, newer AR systems have developed an adjustable headset, a built-in tracking system, and an integrated headlight that projects AR onto a small optical display or directly onto the surgeon's retina.…”

“…To combat such barriers, newer AR systems have developed an adjustable headset, a built-in tracking system, and an integrated headlight that projects AR onto a small optical display or directly onto the surgeon's retina. This form of AR is known as AR-HMD (Figures 3A, 4A) (14).…”

“…Studies have described AR as an alternative to current approaches such as traditional navigation, robotically assisted navigation (RAN), fluoroscopic guidance, and free hand, as it is capable of projecting patient anatomy directly onto the surgical field (2,(4)(5)(6)(7)(8)(9)(10). Therefore, it eliminates surgeon attention shift from the patient to the monitor for guidance (11,12), line-of-sight interruption on live computer navigation, which may result in the loss of live navigation (13), and cumulative exposure to ionizing radiation as patients' demand for MISS continues to grow (14).…”