Fig. 3
From: Navigated 2-level posterior lumbar fusion: a 5-cm-incision procedure
a When a trajectory has been established, a screw will be inserted. b The operator always has the visual of the screw during the course of screw insertion. c, d, Once all the six screws have been inserted, another round of 3D scanning will be performed to check the positions of the screws. After the scanning, the screws are shown in 3D-reconstruction images, and the positions of which can be clearly seen