Fig. 2

Schematic diagram of fracture reduction process. A The pedicle screws were implanted through the lateral screw holes of the arc-shaped plates on both sides, and remained unlocked temporarily. The axial inclination angle of the oblique conical screw hole (15°-20°) was slightly larger than the actual angle of the screw path. B By rotating the adjusting nut with a special instrument, the two arc-shaped plates slided each other, driving the atlas lateral mass to move inward, locking the adjusting nut, and realizing reduction of posterior atlas arch fracture through compression under direct vision. C Then the bilateral pedicle screws were gradually tightened. When locking the screws, the anterior part of the screw drove the lateral mass of the atlas to rotate forward and inward, so as to achieve compression reduction of the anterior atlas arch fracture. D Side view of this screw-plant system. The axis direction of the screw hole and the central plane direction of the plate had a certain angle (10°-15°), so that the plate could be directly attached to the posterior arch of atlas after the screw placement, avoiding the upper edge of the plate from squeezing the posterior arch of atlas, and also reducing the compression of the plate on the axial lamina