Augmented reality-based navigation increases precision of pedicle screw insertion

Abstract

Background: Precise insertion of pedicle screws is important to avoid injury to closely adjacent neurovascular structures. The standard method for the insertion of pedicle screws is based on anatomical landmarks (free-hand technique). Head-mounted augmented reality (AR) devices can be used to guide instrumentation and implant placement in spinal surgery. This study evaluates the feasibility and precision of AR technology to improve precision of pedicle screw insertion compared to the current standard technique. Methods: Two board-certified orthopedic surgeons specialized in spine surgery and two novice surgeons were each instructed to drill pilot holes for 40 pedicle screws in eighty lumbar vertebra sawbones models in an agarbased gel. One hundred and sixty pedicles were randomized into two groups: the standard free-hand technique (FH) and augmented reality technique (AR). A 3D model of the vertebral body was superimposed over the AR headset. Half of the pedicles were drilled using the FH method, and the other half using the AR method. Results: The average minimal distance of the drill axis to the pedicle wall (MAPW) was similar in both groups for expert surgeons (FH 4.8 ± 1.0 mm vs. AR 5.0 ± 1.4 mm, p = 0.389) but for novice surgeons (FH 3.4 mm ± 1.8 mm, AR 4.2 ± 1.8 mm, p = 0.044). Expert surgeons showed 0 primary drill pedicle perforations (PDPP) in both the FH and AR groups. Novices showed 3 (7.5%) PDPP in the FH group and one perforation (2.5%) in the AR group, respectively (p > 0.005). Experts showed no statistically significant difference in average secondary screw pedicle perforations (SSPP) between the AR and the FH set 6-, 7-, and 8-mm screws (p > 0.05). Novices showed significant differences of SSPP between most groups: 6-mm screws, 18 (45%) vs. 7 (17.5%), p = 0.006; 7-mm screws, 20 (50%) vs. 10 (25%), p = 0.013; and 8-mm screws, 22 (55%) vs. 15 (37.5%), p = 0.053, in the FH and AR group, respectively. In novices, the average optimal medio-lateral convergent angle (oMLCA) was 3.23°(STD 4.90) and 0.62°(STD 4.56) for the FH and AR set screws (p = 0.017), respectively. Novices drilled with a higher precision with respect to the cranio-caudal inclination angle (CCIA) category (p = 0.04) with AR. Conclusion: In this study, the additional anatomical information provided by the AR headset superimposed to realworld anatomy improved the precision of drilling pilot holes for pedicle screws in a laboratory setting and decreases the effect of surgeon's experience. Further technical development and validations studies are currently being performed to investigate potential clinical benefits of the herein described AR-based navigation approach.

Augmented reality navigation in spine surgery: a systematic review

“…Nine studies used a dynamic reference frame usually attached to a spinous process or firmly attached to the patients’ skin [ 1 , 10 – 13 , 35 – 37 , 40 ]. Seven studies relied on surface tracking combined with manual adjustments, where the camera system identified patients’ surface anatomy or exposed spinal anatomy [ 14 , 23 , 30 , 31 , 42 , 45 , 46 ]. One study relied on direct surface matching and tracking without the need for manual adjustments [ 44 ].…”

“…Seven studies compared AR to FH with or without fluoroscopy for pedicle screw placement [ 14 , 18 , 19 , 22 , 32 , 38 , 42 ]. The study with the highest available evidence grade was performed by Elmi-Terander et al, comparing a prospective cohort of 20 patients to 20 retrospectively enrolled patients where FH with or without fluoroscopy had been used [ 19 ].…”

Augmented reality-guided periacetabular osteotomy—proof of concept

“…Recent technological improvements, namely, optical see-through head-mounted displays (HMD), such as Microsoft’s HoloLens (Microsoft Corporation, Redmond, WA, USA), are more precise and cost-effective devices. AR navigation of pedicle screw placement has been demonstrated to be feasible with high precision in a self-built setup based on two phantoms of the lumbar spine [ 15 ], and AR navigation improves the precision in drilling pilot holes for pedicle screws in a laboratory setting [ 16 ]. To our knowledge, AR guidance has never been described in the context of acetabular osteotomies (OT), and therefore, its potential merits are largely unknown.…”

Research on Accuracy of Augmented Reality Surgical Navigation System Based on Multi-View Virtual and Real Registration Technology

“…In practice, HMD is the most widely used interactive device [37]. For example, Dennler et al [38]. used head-mounted augmented reality (AR) device to guide the placement of instruments and implants in spinal surgery and achieved good results.…”