title: [Biomechanical evaluation of three-dimensional stability of anterior approach screw fixation through C2 vertebral body to C1 lateral mass].
abstract: OBJECTIVE
  To determine the three-dimensional stability of C1-C2 after anterior approach screw fixation through C2 vertebral body to C1 lateral mass for C1-C2 instability or dislocation.
  
  
  METHODS
  The three-dimensional range of motion of atlantoaxial joint were measured in 16 human cadaveric specimens under four conditions: the intact state (1st group), odontoid fracture of type II (2nd group), instrumentation with posterior C1-C2 trans-articular screw fixation (Magerl technique) (3rd group) and anterior approach screw fixation through C2 vertebral body to C1 lateral mass (4th group) respectively.
  
  
  RESULTS
  There was generally significant difference between 1st group and other groups and between 2nd group and other groups by statistics analysis (P < 0.001). Range of motion significantly decreased in 3rd group and 4th group in all directions. There was generally no significant difference between the two methods by statistical analysis (P > 0.05).
  
  
  CONCLUSIONS
  Anterior approach screw fixation through C2 vertebral body to C lateral mass provides satisfied stability. It provides the equivalent effect to Magerl technique. It is a kind of reliable surgery choice for the treatment of instability or dislocation of C1-C2 joint.
authors.affiliation: Department of Orthopaedics, First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Guo
authors.forename: Zheng-Xue
authors.initials: ZX
authors.lastname: Quan
authors.forename: Yong-Li
authors.initials: YL
authors.lastname: Tang
mesh_terms: D000328:Adult; D001268:Atlanto-Axial Joint / Q000601:surgery*; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D016268:Internal Fixators; D008297:Male