颈椎不同体位致齿状突不同骨折发生机制的有限元分析

Finite element analysis of the different fracture mechanisms of the odontoid process caused by different body positions of the cervical spine

中文关键词:  齿状突骨折  有限元  上颈椎损伤

英文关键词:Odontoid fracture  Finite element  Upper cervical spine injury

中文摘要:

  【摘要】 目的：运用有限元方法分析在不同暴力方向受伤时颈椎体位与不同类型齿状突骨折的相关性。方法：依据前期建立上颈椎有限元模型的经验，并通过与国外发表的文献和体外实验均验证有效的情况下，在所建立的正常枕寰枢复合体三维非线性有限元模型上，预设不同的颈椎体位（中立位、屈曲位、伸位、侧屈位及旋转位），施加加速度为8m/s2的不同方向[前方、后方、侧方、上方（垂直向下）]暴力，计算不同类型的齿状突骨折（Anderson and D′Alonzo分型）各区域的von Mises应力值，并提取应力云图。结果：在受到前方的暴力时，伸位时von Mises应力值最大，应力集中在枢椎椎体（Ⅲ型）（0.41MPa）；在受到后方的暴力时，屈曲位时von Mises应力值最大，应力集中在齿状突基底（Ⅱ型）（0.52MPa）和枢椎椎体（Ⅲ型）（0.55MPa）；在受到侧方来的暴力时，屈曲位时von Mises应力值最大，应力集中在齿状突基底（Ⅱ型）（0.51MPa）和枢椎椎体（Ⅲ型）（0.43MPa）；当受到垂直向下的暴力时，各体位应力值显著升高，其中屈曲位时齿状突尖（Ⅰ型）应力达0.99MPa，侧屈位时齿状突基底（Ⅱ型）应力达1.16MPa，旋转位时枢椎椎体（Ⅲ型）应力为0.85MPa。结论：颈椎处于屈位时受到垂直向下的暴力易出现齿状突尖骨折（Ⅰ型）；颈椎处于屈位时受到后方或侧方暴力或头颈椎处于侧屈位时受到垂直向下的暴力，易出现齿状突基底骨折（Ⅱ型）；颈椎处于屈位时受到后方暴力或头颈椎处于旋转位时受到垂直向下的暴力，易出现枢椎椎体骨折（Ⅲ型）。

英文摘要:

  【Abstract】 Objectives: To analyze the correlation between cervical spine postures and different types of odontoid fractures when injured in different directions of violence using finite element method. Methods: Based on the experience of establishing the finite element model of the upper cervical vertebrae in the early stage, and verified as effective through literature published abroad and in vitro experiments, different positions of the cervical spine(neutral position, flexion position, extension position, lateral bending position, and rotation position) were preset on the established three-dimensional nonlinear finite element model of the normal occipital-atlantoaxial complex, and an acceleration of 8m/s2 was applied in each direction of violence[anterior, posterior, lateral, top(vertical downward)]. The von Mises stress values in different regions of different types(Anderson and D′Alonzo type) of odontoid process fractures were calculated, and stress contour maps were extracted. Results: When subjected to anterior violence, the maximum von Mises stress values were generated in an extension position, with stress concentration in the vertebral body of the axis(Type Ⅲ)(0.41MPa). When subjected to posterior violence, the maximum von Mises stress values were generated when the cervical vertebrae were in a flexion position, with stress concentration in the odontoid process base(Type Ⅱ)(0.52MPa) and the vertebral body of the axis(Type Ⅲ)(0.55MPa). When subjected to lateral violence, the maximum von Mises stress values were generated when the cervical vertebrae were in a flexion position, with stress concentration in the odontoid process base(Type Ⅱ)(0.51MPa) and the vertebral body of the axis(Type Ⅲ)(0.43MPa). When subjected to vertical downward violence, the stress values in each body position increased significantly, the stress at the tip of the odontoid process(Type Ⅰ) in the flexion position reached 0.99MPa, the stress at the base of the odontoid process(Type Ⅱ) in the lateral flexion position reached 1.16MPa, and the stress at the axis vertebral body(Type Ⅲ) in the rotational position was 0.85MPa. Conclusions: When the upper cervical spine is in a flexion position and receives a vertically downward force, it is prone to odontoid process tip fractures(Type I); When the upper cervical spine is in a flexion position and receives a posterior or lateral force, or when it is in a lateral bending position and receives a vertically downward force, it is prone to odontoid process base fractures(Type Ⅱ); When the upper cervical spine is in a flexion position and receives a posterior force, or when it is in a rotational position and receives a vertically downward force, it is prone to axis vertebral body fractures(Type Ⅲ).