[A biomechanical study of anterior screw fixation for type II odontoid fracture with anteroinferior-posterosuperior fracture line].
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.
Fang
Hong-wei
HW
Department of Orthopaedics, Traditional Chinese Medical Hospital of Jiahua, Jinhua 321017, Zhejiang, China. HWF25888@163.com
Li
Jian-jun
JJ
Wu
Zeng-hui
ZH
Ou-Yang
Jun
J
Zhong
Shi-zhen
SZ
Lin
Wen-lu
WL
Jiang
Liang-jun
LJ
Zhao
Jun-qiang
JQ
Yu
Ji-hua
JH
Wang
Xiang-yang
XY
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*