Lapsiwala Samir B, Anderson Paul A, Oza Ashish, Resnick Daniel K
Department of Neurological Surgery, University of Wisconsin Hospital and Clinics, Madison, Wisconsin, USA.
Neurosurgery. 2006 Mar;58(3):516-21; discussion 516-21. doi: 10.1227/01.NEU.0000197222.05299.31.
We performed a biomechanical comparison of several C1 to C2 fixation techniques including crossed laminar (intralaminar) screw fixation, anterior C1 to C2 transarticular screw fixation, C1 to 2 pedicle screw fixation, and posterior C1 to C2 transarticular screw fixation.
Eight cadaveric cervical spines were tested intact and after dens fracture. Four different C1 to C2 screw fixation techniques were tested. Posterior transarticular and pedicle screw constructs were tested twice, once with supplemental sublaminar cables and once without cables. The specimens were tested in three modes of loading: flexion-extension, lateral bending, and axial rotation. All tests were performed in load and torque control. Pure bending moments of 2 nm were applied in flexion-extension and lateral bending, whereas a 1 nm moment was applied in axial rotation. Linear displacements were recorded from extensometers rigidly affixed to the C1 and C2 vertebrae. Linear displacements were reduced to angular displacements using trigonometry.
Adding cable fixation results in a stiffer construct for posterior transarticular screws. The addition of cables did not affect the stiffness of C1 to C2 pedicle screw constructs. There were no significant differences in stiffness between anterior and posterior transarticular screw techniques, unless cable fixation was added to the posterior construct. All three posterior screw constructs with supplemental cable fixation provide equal stiffness with regard to flexion-extension and axial rotation. C1 lateral mass-C2 intralaminar screw fixation restored resistance to lateral bending but not to the same degree as the other screw fixation techniques.
All four screw fixation techniques limit motion at the C1 to 2 articulation. The addition of cable fixation improves resistance to flexion and extension for posterior transarticular screw fixation.
我们对几种C1至C2固定技术进行了生物力学比较，包括交叉椎板（椎板内）螺钉固定、C1至C2前路经关节螺钉固定、C1至2椎弓根螺钉固定以及C1至C2后路经关节螺钉固定。
对8具尸体颈椎在完整状态下以及在齿突骨折后进行测试。测试了四种不同的C1至C2螺钉固定技术。后路经关节和椎弓根螺钉结构进行了两次测试，一次使用辅助椎板下缆线，一次不使用缆线。标本在三种加载模式下进行测试：屈伸、侧弯和轴向旋转。所有测试均在载荷和扭矩控制下进行。在屈伸和侧弯时施加2牛米的纯弯矩，而在轴向旋转时施加1牛米的弯矩。通过刚性固定在C1和C2椎体上的引伸计记录线性位移。使用三角学将线性位移换算为角位移。
添加缆线固定可使后路经关节螺钉的结构更坚固。添加缆线对C1至C2椎弓根螺钉结构的坚固性没有影响。除非向后路结构添加缆线固定，否则前路和后路经关节螺钉技术在坚固性方面没有显著差异。所有三种带有辅助缆线固定的后路螺钉结构在屈伸和轴向旋转方面提供相同的坚固性。C1侧块-C2椎板内螺钉固定恢复了对侧弯的抵抗力，但程度不如其他螺钉固定技术。
所有四种螺钉固定技术均限制了C1至C2关节处的运动。添加缆线固定可提高后路经关节螺钉固定对屈伸的抵抗力。
