216. The arrival of augmented reality in MIS: initial results of use for percutaneous pedicle screw instrumentation

Abstract

<h3>BACKGROUND CONTEXT</h3> Augmented reality (AR) employs computer-generated sensory inputs to enhance the user's perception of his or her environment. Pedicle screw instrumentation has become a mainstay of spinal stabilization. In general, pedicle screw accuracy rates have improved with increasing use of technology; navigation-based instrumentation have been described as accurate in 89-100% of cases. Some inherent difficulties persist with regards to ergonomics and efficiency of spinal navigation. Traditional navigation requires removing focus from the surgical field to interpret and coordinate input of external visual data. Line-of-sight disturbance and attention-shift has known impact on cognitive load and optimization of workflow in surgery. Emerging AR technology in spine surgery aims to reduce the impact of these pitfalls. <h3>PURPOSE</h3> To describe the first known series of in vivo pedicle screws placed percutaneously using AR technology for minimally invasive surgery (MIS) applications. <h3>STUDY DESIGN/SETTING</h3> After IRB approval, three senior surgeons at two institutions collected cases from June, 2020 - October, 2021, in which AR was used for placement of percutaneous pedicle screw instrumentation. <h3>PATIENT SAMPLE</h3> A total of 148 total MIS cases were studied; the average patient age was 59.7 ±13.84 and average BMI was 30.8 ±7.2. <h3>OUTCOME MEASURES</h3> Patient demographics and surgical metrics including total posterior construct time (defined as time elapsed from pre-incision instrument registration, percutaneous posterior fusion and final screw placement) were recorded. Screw revision intraoperatively after fluoroscopic evaluation and revision rates postoperatively were recorded. <h3>METHODS</h3> The xvision^TM (Augmedics Inc., Arlington Heights, IL, USA) system features a wireless headset with transparent near-eye display which projects intraoperative 3D imaging directly onto the surgeon's retina. After patient positioning, one percuntaneous and one superficial reference marker are placed. Intra-operative CT data is processed to the headset and integrates into the surgeon's visual field creating a "see-through" 3D effect in addition to 2D standard navigation images. MIS pedicle screw placement is then carried out percutaneously through single line of sight using navigated instruments. <h3>RESULTS</h3> Of the 148 cases, 139 (93.9%) were performed for degenerative pathology, 6 (4.1%) for tumor and 3 (2.0%) for spinal deformity. A total of 535 pedicle screws were placed; 519 (97.0%) lumbar and 16 (3.0%) thoracic. Eighty-four (58.8%) cases were 1-level, 42 (28.4%) were 2-level, 16 (10.8%) were 3-level and 6 (4.1%) were 4-level, equating to an average of 3.51 screws per case. A total of one screw (0.20%) was replaced intraoperatively after examining position with fluoroscopy. No instrumentation was revised postoperatively at final available follow-up ranging from 3-18 months. The mean total posterior construct time was 5 minutes and 56 seconds per screw overall; cases later in the learning curve achieved total posterior construct mean time of 2 minutes and 51 seconds per screw. <h3>CONCLUSIONS</h3> This study represents the first report of the use of AR to place MIS pedicle screws. These data support an exceedingly low rate of complications with screw placement and confirms a rapid learning curve with a high level of surgical efficiency demonstrated. These advances are achieved with an image- and implant-agnostic system which requires no physical footprint in the operating room. <h3>FDA DEVICE/DRUG STATUS</h3> xvision^TM (Augmedics Inc., Arlington Heights, IL, USA) (Approved for this indication)