Quantitative Volumetric Analysis and the Novel Use of a Direct Augmented Reality Overlay During Medial Facetectomy in a 3D Printed Patient Specific Model

Introduction: The goal of augmented reality (AR) is to enhance native perception and vision allowing an individual to experience computerized information as a real time overlay in the natural visual field (NVF). The use of AR during neurosurgical procedures allows for a direct overlay of three-dimensional information into surgeon’s view of the surgical field. In this study we seek to performed the first quantitative analysis of the utility of augmented reality to assist a surgeon during a common neurosurgical procedure, mesial facetectomy.

Methods: Institutional (IRB) approval was obtained for this prospective experimental study. Resident and attending neurosurgeons completed bilateral hemilaminectomies and mesial 1/3rd facetectomies on a 3D printed patient specific degenerative lumbar spine model. Participants completed the procedure using their NVF and then a using a pre-rendered “true” 1/3rd by volume mesial facetectomy guide. This guide was overlayed over each operative joint to guide the procedure. Pre/post-operative high-definition CT scans were completed and voxel subtraction was used to calculate the amount of joint removed.

Results: Two neurosurgical attendings and three residents (PGY 1,3,7) completed the study. 50 total levels were drilled in the NVF and AR groups totaling 100 levels. Regardless experience level AR guidance was associated with an improvement in performance. Statistical analysis found a significant difference between the two groups with a mean drilled volume of 15.3% without AR and 22.6 % with AR (P < 0.001). AR guidance improved surgeon performance during maximal targeted decompression by an average of 20.1%, raising the achieved decompression to target goal from 48.5% to 68.6% (P < 0.05).

Conclusion : Here we provide data to support that AR guidance can significantly improve procedural preference across training levels including neurosurgical attendings during non-instrumented procedures. Systematic and controlled studies of AR is required to further understand its affect on neurosurgeon training and intraoperative judgement.