Deviation from preoperative planning and pedicle screw accuracy in navigated and robotic spinal fusion: a systematic review

Purpose: Image-guided navigation and robotic systems have been introduced in spinal surgery to increase the accuracy of pedicle screws placement and reduce the rate of complications. The objective of this study is to evaluate the different final screw deviation from pre-operative planning and the associated pedicle screw accuracy in spinal fusion surgery assisted by image-guided navigation or robotic systems. Methods: The systematic literature search was executed using PubMed–Medline, Cochrane Central, and Scopus on 30 April 2023. Studies that explored the deviation between final position and preoperative planning of pedicle screws assisted by image-guide navigation or robotic system were included. The data extracted were surgical approach, surgical aid, number of screws evaluated, spinal levels, accuracy and deviation of screws. The quality of the studies was assessed using the revised Cochrane risk-of-bias tool for randomized trials (RoB 2) or the methodological index for non-randomized studies (MINORS) score. Results: This review included 15 studies, of which 5 used navigation and 10 robotic system. The studies involved 1487 patients, with the evaluation of a total of 7274 pedicle screws, with an assessment of planning and final position. The different methodologies to calculate the deviation include angular deviations in the axial and sagittal plane, 3D angular deviation, and tip and entry point deviation. Regarding screw accuracy, 98.15% of the screws were grade A or B, and 1.85% as category C or D. Conclusion: Although preoperative planning allows the surgeon to plan the final position of the screw most appropriately, mild deviations from it do not seem to excessively influence the accuracy of the spinal fusion.