Wu Weidong, Sun Peidong, Liu Xiong, Chen Chun, Wu Changfu, Ouyang Jun
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2013 Dec;27(12):1466-70.
To compare the biomechanical properties of the anterior transpedicular screw-artificial vertebral body (AVB) and conventional anterior screw plate system (AP) in lower cervical spine by finite element study.
CT images (C1-T1) were obtained from a 38-year-old female volunteer. The models of intact C(3-7) (intact group), AP fixation (AP group), and AVB fixation (AVB group) were established and analyzed by Mimics 14.0, Geomagic Studio 2013, and ANSYS 14.0 softwares. The axial force of 74 N and moment couple of 1 N x m were loaded on the upper surface and upper facet joint surfaces of C3. Under conditions of flexion, extension, lateral bending, and rotation, the Von Mises stress distribution regularity and maximum equivalent stree of AP and AVB groups were recorded, and the range of motion (ROM) was also analyzed of 3 groups.
The intact model of lower cervical spine (C(3-7)) was established, consisting of 286,382 elements and 414,522 nodes, and it was successfully validated with the previously reported cadaveric experimental data of Panjabi and Kallemeyn. The stress concentrated on the connection between plate and screw in AP group, while it distributed evenly in AVB group. Between AP and AVB groups, there was significant difference in maximum equivalent stress values under conditions of 74 N axial force, flexion, extension, and rotation. AVB group had smaller ROM of fixed segments and larger ROM of adjacent segments than AP group. Compared with intact group, whole ROM of the lower cervical spine decreased about 3 degrees, but ROM of C(3,4) and C(6,7) segments increased nearly 5 degrees in both AP and AVB groups.
As a new reconstruction method of lower cervical spine, AVB fixation provides better stability and lower risk of failure than AP fixation.
通过有限元研究比较下颈椎前路经椎弓根螺钉-人工椎体（AVB）与传统前路钢板螺钉系统（AP）的生物力学特性。
从一名38岁女性志愿者获取C1-T1的CT图像。利用Mimics 14.0、Geomagic Studio 2013和ANSYS 14.0软件建立并分析完整C(3-7)模型（完整组）、AP固定模型（AP组）和AVB固定模型（AVB组）。在C3上表面和上关节突表面施加74 N的轴向力和1 N·m的力矩。在屈伸、侧弯和旋转条件下，记录AP组和AVB组的Von Mises应力分布规律及最大等效应力，并分析3组的活动度（ROM）。
建立了下颈椎（C(3-7)）完整模型，包含286,382个单元和414,522个节点，并用Panjabi和Kallemeyn先前报道的尸体实验数据成功验证。AP组应力集中在钢板与螺钉连接处，而AVB组应力分布均匀。在74 N轴向力、屈伸和旋转条件下，AP组和AVB组的最大等效应力值有显著差异。AVB组固定节段的ROM较小，相邻节段的ROM比AP组大。与完整组相比，下颈椎的整体ROM减少约3度，但AP组和AVB组C(3,4)和C(6,7)节段的ROM增加近5度。
作为下颈椎的一种新的重建方法，AVB固定比AP固定提供更好的稳定性和更低的失败风险。
