Fig. 3

A 38-year-old women with lumbar spondylolisthesis (L5) and unstable spine. Anteroposterior-view radiograph (a) and lateral-view radiograph (b) before surgery. After selecting the screw entry point, a pedicle drill was projected to the site from the lower edge of the first superior articular process of the first sacrum to the first posterior sacral foramina on the contralateral side of the entry point, and the pedicle drill was close to the upper edge of the supraspinous ligament (c). After completion of screw placement, the radiographic teardrop view (axial view of the screw) shows the position of the screw was satisfactory (d). Postoperative follow-up anteroposterior (e) and lateral views (f) show that the slipped vertebrae were reduced, and the S2AI screw and other screws were in the desired places