Hangman骨折相关三维有限元模型的建立和验证

Establishment and verification of a three-dimensional finite element model of Hangman fracture

背景：目前有关上颈椎多节段有限元模型的相关文献很少,尚无建立Hangman骨折有限元模型的报道。目的：建立C2~4节段正常颈椎及不同程度Hangman骨折的三维有限元模型,并对各模型进行模拟及加载验证。方法：选择一健康成年男性志愿者进行C2~4节段CT扫描,以CT扫描图像为基础,在计算机工作站利用ANSYS等有限元分析软件,建立C2~4节段颈椎三维有限元模型,模型包括椎体和椎弓、椎间盘、韧带成分,在此模型基础上逐步模拟切断双侧C2椎弓峡部、切除C2~3前纵韧带和部分椎间盘的Hangman骨折模型,分别计算正常颈椎、不同Hangman骨折模型在模拟施加50N载荷下,C2~3,C3~4节段三维六自由度的角位移（ROM）。结果与结论：C2~3节段Hangman骨折加韧带椎间盘切除模型在各个方向上均较正常和固定模型ROM增大,在屈伸运动时增大最明显,而在旋转和侧屈时与正常标本相差不多。C3~4节段各组间的ROM相差不超过0.16°。各种三维有限元模型的位移和应力验证结果与实验生物力学结果基本相符,提示建立的三维有限元模型可以模拟颈椎生物力学实验。

BACKGROUND： Currently, there are few studies on finite element model of multi-segmental cervical and no studies on finite element model of Hangman fracture. OBJECTIVE： To establish three-dimensional finite element models of normal C2-4 segments and Hangman fractures in various degrees, as well as simulate and verify the models. METHODS： CT scanning of the C2-4 segment was performed in an adult male volunteer in order to establish the three-dimensional finite element model of C2-4 segment using three-dimensional finite elements analysis software including ANSYS at computer workstation. The model included the vertebral body, arch of vertebra, intervertebral disc and the ligament. The Hangman fracture model was prepared by cutting off bilateral isthmus of C2, the anterior longitudinal ligament of C2-3 and part of the intervertebral disc based on this model. Range of motion （ROM） at three dimensions in six directions of C2-3 and C3-4 segments under simulated 50 N loading was calculated in normal or Hangman fracture models. RESULTS AND CONCLUSION： C2-3 segment： ROM of the Hangman fracture ＋ ligament intervertebral disc resection model was larger than that of the normal model in all directions, especially in directions of flexion and extension, however, the ROM was the same on rotation and lateral flexion to that of the normal model. C3-4 segment： the ROM of the two groups was similar, and the difference was no larger than 0.16°. The displacement results were basically consistent with those of the stress testing of the three-dimensional finite element models. The three-dimensional finite element models can be used for simulating biomechanics of Hangman fractures.