title: Computerized tomographic measurements of morphometric parameters of the c2 for the feasibility of laminar screw fixation in korean population.
abstract: OBJECTIVE
  C2 laminar screw fixation is considered as an excellent alternative to Magerl's transfacetal approach or Harms construct for the atlantoaxial stabilization. However, to our knowledge, there is no report on the feasibility of the new approach to Korean population. We investigated morphometric parameters of the dorsal arch of the C2 to provide the quantitative data for the feasibility of laminar screw fixation.
  
  
  METHODS
  One-hundred-and-two patients' cervical computed tomography had been reconstructed and investigated on the anatomical parameters related with C2 laminar screw placement. Sixty patients were male and forty-two patients were female. Measurements included the laminar thickness and slope, spino-laminar angle, and maximal screw length.
  
  
  RESULTS
  Ages ranged from 20 to 81 and the mean age was 48.4. Mean laminar thickness was 5.7 mm (+/-1.0) (5.8 mm in male and 5.4 mm in female). Fifty-one patients (50%) had a laminar thickness smaller than 5.5 mm at least unilaterally, therefore the patients were considered as inappropriate candidates for the laminar screw fixation in the smaller side of the laminae. Mean value of maximal length of screw was 33.3 mm (34.3 mm in male and 31.9 mm in female). Mean spino-laminar angle was 43.2 degrees and mean slope angle was 32.9 degrees .
  
  
  CONCLUSIONS
  Half of patients had inappropriate laminar profiles to accommodate a 3.5 mm screw in at least one side of the axis. The three-dimensional computed tomography reconstruction is mandatory for the preoperative assessment for the feasibility of the C2 lamina.
authors.affiliation: Department of Neurosurgery, Gangneung Asan Hospital, College of Medicine, University of Ulsan, Gangneung, Korea.
authors.forename: Young-June
authors.initials: YJ
authors.lastname: Kim
authors.forename: Woo Tack
authors.initials: WT
authors.lastname: Rhee
authors.forename: Sang-Bok
authors.initials: SB
authors.lastname: Lee
authors.forename: Seung-Hoon
authors.initials: SH
authors.lastname: You
authors.forename: Sang-Youl
authors.initials: SY
authors.lastname: Lee