title: [A biomechanical study of anterior screw fixation for type II odontoid fracture with anteroinferior-posterosuperior fracture line].
abstract: OBJECTIVE
  To investigate the biomechanical effect of anterior screw fixation on the type II fractured odontoid process.
  
  
  METHODS
  Twenty fresh human C1-C2 vertebrae specimens were harvested and randomly divided into three groups. The angle of type II fracture line was 0 degree in group I (n=6), 17 degrees in group II (n=8) and 25 degrees in group III (n=6). The fractures were treated by anterior screw fixation. Insertion torque,maximal axial pullout force and stiffness of the bone-screw were tested.
  
  
  RESULTS
  There was no significant difference of screw insertion torque and the pull-out strength between each group. The displacement of the odontoid fragment had an association to the angle of the fracture line,the displacement of the small angle was significantly higher than that of the large one (P < 0.5). No significant difference of structure stiffness of the bone-screw was found between each group.
  
  
  CONCLUSIONS
  Anterior screw fixation is feasible for type II odontoid fracture with certain fracture line extends from anteroinferior to posterosuperior.
authors.affiliation: Department of Orthopaedics, Traditional Chinese Medical Hospital of Jiahua, Jinhua 321017, Zhejiang, China. HWF25888@163.com
authors.forename: Hong-wei
authors.initials: HW
authors.lastname: Fang
authors.forename: Jian-jun
authors.initials: JJ
authors.lastname: Li
authors.forename: Zeng-hui
authors.initials: ZH
authors.lastname: Wu
authors.forename: Jun
authors.initials: J
authors.lastname: Ou-Yang
authors.forename: Shi-zhen
authors.initials: SZ
authors.lastname: Zhong
authors.forename: Wen-lu
authors.initials: WL
authors.lastname: Lin
authors.forename: Liang-jun
authors.initials: LJ
authors.lastname: Jiang
authors.forename: Jun-qiang
authors.initials: JQ
authors.lastname: Zhao
authors.forename: Ji-hua
authors.initials: JH
authors.lastname: Yu
authors.forename: Xiang-yang
authors.initials: XY
authors.lastname: Wang
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000293:injuries*; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D016103:Spinal Fractures / Q000503:physiopathology / Q000601:surgery*