title: Feasibility study on posterior laminar screw fixation techniques in the axis.
abstract: OBJECTIVE
  To get morphologic parameters of Chinese adults through observation and measurement on axial laminas, to evaluate the feasibility of placing axial laminar screws and to introduce the technique.
  
  
  METHODS
  Relative parameters of 28 sets of fresh Chinese adults'axial specimens, including distance from the superior and inferior entry points of axial laminar screws to the superior margins of axial laminas, superior, middle, inferior thickness and height of the axial laminas, length and angle of the axial laminar screw trajectories, distance from the entry points of axial laminar screws to the transverse foramen and central points of the inferior articular process, were measured with a digital caliper and a goniometer. Data were statistically analyzed.
  
  
  RESULTS
  Averagely, distance from the superior and inferior entry points of axial laminar screws to the superior margins of axial laminas was 5 mm and 9 mm, superior, middle, inferior thickness and the height of the axial laminas were 3.2 mm, 6.7 mm, 5.5 mm and 12.8 mm respectively, and the length of the superior and inferior axial laminar screw trajectories was 26.2 mm and 25.5 mm, respectively.
  
  
  CONCLUSIONS
  It is feasible and reliable to apply posterior laminar screw fixation techniques to the axes of Chinese adults. Also the C2 laminar screw fixation technique can be taken as a supplementary to conventional posterior screw fixations of C2.
authors.affiliation: Department of Orthopaedics, Ningbo 6th Hospital, Ningbo, China. huyong610@163.com
authors.forename: Yong
authors.initials: Y
authors.lastname: Hu
authors.forename: Xian-feng
authors.initials: XF
authors.lastname: He
authors.forename: Yong-jie
authors.initials: YJ
authors.lastname: Gu
authors.forename: Rong-ming
authors.initials: RM
authors.lastname: Xu
authors.forename: Wei-hu
authors.initials: WH
authors.lastname: Ma
authors.forename: Yong-ping
authors.initials: YP
authors.lastname: Ruan
authors.forename: Rong
authors.initials: R
authors.lastname: Lin
mesh_terms: D000328:Adult; D000368:Aged; 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*