In-Human Report of S2 Alar-Iliac Screw Placement Using Augmented Reality Assistance

Abstract

BACKGROUND: 

S2 alar-iliac (S2AI) screws provide spinopelvic fixation with the advantages of minimized dissection, easier rod contouring, and decreased symptomatic screw-head prominence. However, placement of S2AI screws may be challenging because of the anatomy of the lumbosacral junction. Augmented reality is a nascent technology that may enhance placement of S2AI screws.

OBJECTIVE: 

To report the first in-human placement of augmented reality (AR)–assisted S2 alar-iliac screws and evaluate the accuracy of screw placement.

METHODS: 

A retrospective review was performed of patients who underwent AR-assisted S2AI screw placement. All surgeries were performed by 2 neurosurgeons using an AR head-mounted display (Xvision, Augmedics). Screw accuracy was analyzed in a blinded fashion by an independent neuroradiologist using the cortical breach grading scale.

RESULTS: 

Twelve patients underwent AR-assisted S2AI screw placement for a total of 23 screws. Indications for surgery included deformity, degenerative disease, and tumor. Twenty-two screws (95.6%) were accurate—defined as grade 0 or grade 1. Twenty-one screws (91.3%) were classified as grade 0, 1 screw (4.3%) was grade 1, and 1 screw (4.3%) was grade 3. All breaches were asymptomatic.

CONCLUSION: 

AR-assisted S2AI screw placement had an overall accuracy rate of 95.6% (grade 0 and grade 1 screws) in a cohort of 12 patients and 23 screws. This compares favorably with freehand and robotic placement.^1,2 AR enables spine surgeons to both better visualize anatomy and accurately place spinal instrumentation. Future studies are warranted to research the learning curve and cost analysis of AR-assisted spine surgery.