Fig. 2

The operative segment is confirmed to be in absolute lateral position under fluoroscopy and the surface location is marked. a The spinous process is located in the center between two pedicles in anteroposterior X-ray. b The upper endplate of caudal vertebrae overlaps in a line and the affected disc space is marked with 2 K-wires in lateral X-ray. c The surface location of the affected disc space is marked on the patient’s lateral side