title: [Anatomic study of the posterior laminar screw fixation on C7].
abstract: OBJECTIVE
  To measure anatomic data of laminar of C7 and evaluate the possibility of the placement of C7 laminar screw.
  
  
  METHODS
  Twenty-two specimens of C7 were measured with an vernier caliper and a goniomete and finded out the anatomic data for prominent vertebra laminar screw placement. The indicators included the thickness of the superior, median and inferior part of C7 laminar (T1, T2, T3), the height of the laminar(H), the distance of the anchor point to the medial wall of C7 pedicle and the lateral wall of the lateral mass (L1, L2) and the angle between the axis of C7 lamina and sagittal plane(alpha).
  
  
  RESULTS
  The mean thickness of superior part of C7 lamina (T1) was (4.30 +/- 0.27) mm, (5.32 +/- 0.27) mm in median part (T2) with 27% (6 cases) of specimens thickness less than 4.50 mm and (4.78 +/- 0.26) mm in inferior part (T3). Both median part and inferior part were thicker than 4.50 mm. The mean height of C7 laminar (H) was (14.83 +/- 0.26) mm. The distance from the laminar anchor point to the medial wall of C7 pedicle (L1) and the lateral wall of the lateral mass (L2) was (26.99 +/- 0.48) mm and (41.60 +/- 1.10) mm respectively. The mean angle between the axis of C7 laminar and sagittal plane(alpha) was (49.3 +/- 1.1) degrees.
  
  
  CONCLUSIONS
  It is feasible to place screw in C7 laminar and this technique can be applied in 73% of Chinese. Compared with C7 pedicle screw technique, this technique is simple with little risk to the nerve and vascular structures.
authors.affiliation: Department of Orthopaedics, Ningbo No. 6 Hospital, Ningbo 315040, Zhejiang, China. caojin111@163.com
authors.forename: Jin
authors.initials: J
authors.lastname: Cao
authors.forename: Rong-Ming
authors.initials: RM
authors.lastname: Xu
authors.forename: Zhao-Ping
authors.initials: ZP
authors.lastname: Zhong
authors.forename: Wei-Hu
authors.initials: WH
authors.lastname: Ma
authors.forename: Liu-Jun
authors.initials: LJ
authors.lastname: Zhao
authors.forename: Ming
authors.initials: M
authors.lastname: Li
mesh_terms: D000328:Adult; D001863:Bone Screws; D005240:Feasibility Studies; D006801:Humans; D016268:Internal Fixators; D013131:Spine / Q000033:anatomy & histology* / Q000601:surgery*