Fig. 2

The entry points and trajectories were shown. In the anteroposterior view (a), the pedicle can be regarded as a clock face; the insertion was started at the 5 o’clock (green circle) position and aimed for 11 o’clock (red circle) orientation in the left pedicle, whereas insertion in the right pedicle began at the 7 o’clock (green circle) position and aimed for 1 o’clock (red circle) orientation. The endpoint (red circle) was set at the midpoint of the superior endplate without perforation in the lateral view (b)