Fig. 2

A-K. An illustrative case (patient no. 2) of CSGS technique. Preoperative MRI after neo-adjuvant chemotherapy showed tumor extent (A). A canulated screw was placed at middle point of L5/S1 level without penetration of the anterior cortex under fluoroscopic guidance (B). Penetration of the cannulated screw through the anterior cortex was confirmed by finger palpation by a pedicle sound (C). D and E showed a Gigli saw was introduced through the canulated screw and the planned osteotomy site (dash line on figure E). Then the iliac osteotomy was carried out through posterior approach (F and G). The tumor was removed after resection of ipsilateral half of L5/S1 disk (H). The specimen was showed (I and J). Postoperative X-ray showed osteotomy sites and reconstruction