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 (FH) technique.
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 operating room (OR) with a ceiling-mounted robotic C-arm with integrated video cameras for AR navigation. The FH group was 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 PS density, 86.3% ± 14.6% versus 74.7% ± 13.9% in the FH group (P < 0.05), whereas the hook density was 2.2% ± 3.0% versus 9.7% ± 9.6% (P < 0.001). Neither the total procedure time (min) 431 ± 98 versus 417 ± 145 nor the deformity correction 59.3% ± 16.6% versus 60.1% ± 17.8% between the groups were significantly affected.
Conclusion: 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: 3.