(0538) Virtual Surgical Guides in Craniomaxillofacial Surgery Using Augmented Reality

Introduction: Augmented reality (AR) is a promising tool for overlaying patient-specific data (i.e., CT, MRI) onto patients during surgery. For this technology to be translated into the operating room (OR), more research on data registration and projection accuracy must be performed. The purpose of this study was to examine the accuracy of AR-projected virtual surgical guides (VSGs) (i.e., virtual cutting & drilling guides) in craniomaxillofacial surgery on skull models in a controlled lab setting and on patients in the operating room.

Methods: AR software was provided by Xironetic and deployed onto a Microsoft HoloLens 2 head-mounted display. A control skull model was created by drilling 6 holes in the lateral orbit, 6 holes in the orbital floor, and 10 holes in the temporal bone. The control model was scanned via CBCT, segmented data was loaded into the AR software, the data was registered to a new test skull, and the 22 holes were drilled by a surgeon using the AR overlay. The test models were scanned via CBCT and computationally compared to the control model. A similar method was used on one patient undergoing a bony tumor resection of the zygoma where accuracy was measured from marks made with a marking pen outlining the planned resection.

Results: The absolute positional error of each VSG-placed hole averaged 1.65 mm (σ = 1.02 mm). The lateral orbit holes displayed the greatest positional error (2.06 mm, n=42), followed by the orbital floor (1.60 mm, n=42) and the temporal bone (1.29 mm, n=70), which was the most accurate. VSG placement intraoperatively was qualitatively less accurate (n=1) than on the lab skull models.

Conclusions: In a lab setting, VSG accuracy ranged from 1.29 to 2.06 mm on average, depending on the anatomic area. Accuracy was lowest in the lateral orbits, likely due to the surface complexity of that anatomic region. Additional VSG accuracy on patients in the OR will be collected over the next 9 months, and strategies for translation will be formulated. VSGs have the potential to allow for more accurate drilling in areas with complex regional anatomy or difficult intraoperative exposure.