Accuracy of computer-assisted pedicle screw placement for adolescent idiopathic scoliosis: a comparison between robotics and navigation

Purpose To compare the accuracy of pedicle screw placement in adolescent idiopathic scoliosis (AIS) between robotics and navigation and clarify the factors that cause screw deviation when robotics is used. Methods Fifty consecutive patients who underwent posterior spinal fusions with computer-assisted pedicle screw placement including robotics and navigation for AIS were included. A total of 741 pedicle screws (250: Robot group, 491: Navi group) were evaluated on postoperative CT images. A rate of penetration of >= 2 mm was calculated as the deviation rate. After propensity score matching, we examined vertebral levels, the distance from the reference frame (RF), and the pedicle channel grade as factors for deviation. Results The deviation rate was significantly lower in the Robot group than in the Navi group (Robot group: 1.6%, Navi group: 7.5%). After propensity score matching, 22 cases were extracted. At T5-T8, the deviation rate of the Robot group was significantly lower than that of the Navi group. In the Robot group, the T2-T4 deviation rate was significantly higher than at the other vertebral levels. The distance from the RF didn't affect the deviation rate. The deviation rate of pedicle channel Grade 4 (inner diameter of less than 1 mm) was significantly higher than for the other grades. Conclusion The deviation rate of robotics was 1.6%, lower than that of navigation. The narrow pedicles with an inner diameter of less than 1 mm (deviation rate: 22.2%) and the upper thoracic level (deviation rate: 14.3%) were factors related to screw deviation even when using robotics.