title: [An anatomic study of posterior C(2) spinous process laminar screw fixation].
abstract: OBJECTIVE
  To explore the feasibility and the technical parameters in posterior C2 spinous process laminar screw fixation, and discuss the clinic significance of C2 spinous process laminar screws.
  
  
  METHODS
  Twenty cervical cadaveric spines of C2 were dissected, with care taken to expose the lamina and spinous process. After the entrance point of spinous process screw were determined, posterior C2 spinous process laminar screw implantation was performed under visual control. On the morphologic CT scan, the angle and length of the spinous process laminar screw trajectory and the distance between the tip of the screw and the spinal cord and the vertebral artery were measured.
  
  
  RESULTS
  The C2 spinous process laminar screws were successfully placed, without impingement of the spinal cord and the vertebral artery. There were little differences between superior and inferior screws in the angle, trajectory length and the distance between the tip of the screw and the spinal cord and the vertebral artery, but without significance (P > 0.05). The placed angles of the screws were 76.8° ± 10.6° in the axial plane. The distance between the tip of the screw and the spinal cord and the vertebral artery was (5.3 ± 1.6) mm and (17.4 ± 3.7) mm respectively. The trajectory length was (23.1 ± 3.2) mm.
  
  
  CONCLUSIONS
  Posterior C2 spinous process laminar screw fixation is feasible. C2 spinous process laminar screw fixation affords an alternative to standard screw placement for plate fixation and cervical stabilization.
authors.affiliation: Department of Orthopaedics, Ningbo Sixth People's Hospital, Ningbo, China.
authors.forename: Guan-Yi
authors.initials: GY
authors.lastname: Liu
authors.forename: Rong-Ming
authors.initials: RM
authors.lastname: Xu
authors.forename: Wei-Hu
authors.initials: WH
authors.lastname: Ma
authors.forename: Shao-Hua
authors.initials: SH
authors.lastname: Sun
authors.forename: Hua-Jie
authors.initials: HJ
authors.lastname: Lin
authors.forename: Jian-Xiang
authors.initials: JX
authors.lastname: Feng
authors.forename: Yong
authors.initials: Y
authors.lastname: Hu
authors.forename: Liu-Jun
authors.initials: LJ
authors.lastname: Zhao
authors.forename: Lei-Jie
authors.initials: LJ
authors.lastname: Zhou
mesh_terms: D000328:Adult; D001368:Axis, Cervical Vertebra / Q000601:surgery*; D001863:Bone Screws; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013123:Spinal Fusion / Q000379:methods; D055815:Young Adult