Does Augmented Reality Navigation Increase Pedicle Screw Density Compared to Free-Hand Technique in Deformity Surgery? Single Surgeon Case Series of 44 Patients.

STUDY DESIGN: Retrospective comparison between an interventional and a control cohort. OBJECTIVE: The aim of this study was to investigate whether the use of an augmented reality surgical navigation (ARSN) system for pedicle screw (PS) placement in deformity cases could alter the total implant density and PS to hook ratio compared to free-hand technique (FH). SUMMARY OF BACKGROUND DATA: Surgical navigation in deformity surgery provides the possibility to place PS in small and deformed pedicles were hooks would otherwise have been placed, and thereby achieve a higher screw density in the constructs that may result in better long-term patient outcomes. METHODS: Fifteen deformity cases treated with ARSN were compared to 29 cases treated by FH. All surgeries were performed by the same orthopedic spine surgeon. PS, hook and combined implant density were primary outcomes. Procedure time, deformity correction, length of hospital stay and blood loss were secondary outcomes. The surgeries in the ARSN group were performed in a hybrid OR with a ceiling-mounted robotic C-arm with integrated video cameras for AR navigation. The FH group were operated with or without fluoroscopy as deemed necessary by the surgeon. RESULTS: Both groups had an overall high-density construct (>80% total implant density). The ARSN group, had a significantly higher pedicle screw density, 86.3 ± 14.6% vs 74.7 ± 13.9% in the FH group (p < 0.05), while the hook density was 2.2 ± 3.0% vs 9.7 ± 9.6% (p < 0.001). Neither the total procedure time (min) 431 ± 98 vs 417 ± 145 nor the deformity correction 59.3 ± 16.6% vs 60.1 ± 17.8% between the groups were significantly affected. CONCLUSIONS: This study indicates that ARSN enables the surgeon to increase the PS density and thereby minimize the use of hooks in deformity surgery without prolonging the OR-time. This may result in better constructs with possible long-term advantage and less need for revision surgery. LEVEL OF EVIDENCE: 4.