Fig. 2

a The spinous process and lamina and bilateral articular process in affected segment were removed so as to expose the dural sac and intervertebral disc. b The intervertebral space was hollowed out to form an “eggshell,” after the removal of disc tissue within the intervertebral space. c The adhesion between the herniated calcified disc and dura mater was separated by a nerve retractor crook or hook knife, and the hardening disc tissue was pushed to the anterior intervertebral space by the reverse angled curette. d Autologous bone graft and a cage were implanted into the interbody for fusion purpose. The pedicle screw-rod system was fixed in situ in order to prevent a slight curvature change after decompression, thereby reducing damage to the spinal cord