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Proof-of-Concept Study: Evaluation of A Novel Augmented Reality Overlay for Cervical Screw Placement in Phantom Spine Models

Wednesday, February 21, 2024

Presenting Author(s)

Brian Shear, MD (he/him/his)

Current Resident
University of Maryland Medical Center
Baltimore, Maryland, United States

Co-Author(s)

NH

Nathan Han, MD

Resident Physician
University of Maryland Medical Center
Baltimore, Maryland, United States
Steven Ludwig, MD

Attending Physician
University of Maryland Medical Center, United States
Joshua Olexa, MD

Resident Physician
University of Maryland Medical Center
Baltimore, Maryland, United States
Charles Sansur, MD, MHSc

Attending Physician
University of Maryland Medical Center
Baltimore, Maryland, United States
Gary Schwartzbauer, MD, PhD

Professor
University of Maryland Medical Center
Baltimore, Maryland, United States
AS

Ashish Sharma, MD

Resident Physician
University of Maryland Medical Center, United States

Introduction: The use of navigation is extremely common in spine surgery. Despite this, there are numerous factors that limit widespread adoption of navigation during spine surgery. Augmented reality (AR) is a new technology that has already demonstrated utility as a navigation tool during spine surgery. This study evaluates the feasibility of a novel low-profile AR system as a navigation tool for placement of spinal instrumentation in cervical spine phantom models.

Methods: A novel AR system that uses a fiducial-less registration system was tested in a preclinical cervical spine phantom model study for accuracy during spinal screw placement. Two cervical spine models were scanned using CT imaging. A 3D reconstruction of the spine along with pre-planned trajectory lines was generated from the CT images and superimposed onto the phantom model through an AR headset. Participants used the AR system to guide screw placement. Post-instrumentation CT scans were obtained, and screw trajectory metrics of insertion point error (IPE), target point error (TPE), and target angle error were analyzed and compared to pre-planned trajectories for accuracy assessment.

Results: Twelve cervical screws were placed under AR guidance (in levels C2-C3 in Model 1 and C3-C6 in Model 2) . All screws were placed in an acceptable anatomic position. The average IPE was 2.73 +/- 0.55mm. The average TPE was 2.71 +/- 0.69mm. The average TAE for all insertions was 2.69 +/- 0.59 degrees. There were no significant differences for IPE, TPE, or TAE between cervical level instrumented or instrumentation laterality.

Conclusion : This proof-of-concept study provides further support for the potential navigation use case for this novel AR system. The results demonstrate reasonable accuracy and consistency amongst spinal levels instrumented in a preclinical model. While significant further validation is warranted, this preliminary data is encouraging and warrants further testing in cadaveric and clinical models.