儿童颈椎C2~C7节段生物力学特性的有限元研究

Finite Element Study on Biomechanical Characteristics of C2~C7 Segments of Cervical Spine in Children

摘要: 研究儿童正常颈椎C2~C7节段的生物力学特性和不同载荷作用下儿童颈椎生物力学特性的变化规律。基于儿童颈椎CT数据，建立两个6岁儿童C2~C7颈椎有限元模型并验证有效性，施加21 N集中力和0.5、1.0、1.5、2.0 N∙m力矩分析不同工况下颈椎的关节活动度(range of motion, ROM)、椎体应力和椎间盘压力的分布特征。结果表明，力矩等值增加时两模型C2~C7颈椎ROM和应力在前屈、后伸、侧弯和旋转工况均呈现非线性增长。21 N集中力和0.5 N∙m力矩下模型1和模型2颈椎C2~C7整体ROM在前屈、后伸、侧弯和旋转时分别为8.3˚、19.07˚、25.14˚、28.2˚和10.91˚、20.08˚、18.92˚、27.61˚，两模型1.0、1.5、2.0 N∙m力矩下较0.5 N∙m时ROM最大分别增加了21.19˚、27.84˚、36.83˚和19.08˚、30.05˚、38.31˚。21 N集中力和0.5 N∙m力矩下模型1和模型2颈椎C2~C7椎体最大应力在前屈、后伸、侧弯和旋转时分别为3.19、11.75、5.93、4.84 MPa和3.96、9.81、6.71、5.89 MPa，两模型1.0、1.5、2.0 N∙m力矩下较0.5 N∙m时应力最大增幅分别为133.54%、203.76%、286.21%和83.33%、138.38%、220.20%。儿童椎间盘应力均为前屈时最小、后伸时最大，椎体与椎间盘应力分布特征与前人研究基本一致。两儿童ROM、应力大小与分布特征相近，儿童C2~C7颈椎ROM大于成人，椎体与椎间盘应力值小于成人，对儿童颈椎病进行预防治疗时应考虑儿童颈椎与成人的差异。

Abstract: To investigate the biomechanical characteristics of normal cervical vertebra C2~C7 segments in children and the variations in the biomechanical characteristics of the pediatric cervical spine un-der different loads. Finite element models of the C2~C7 cervical spine for 6-year-old children were established based on cervical spine CT data and validated for effectiveness, applying loads of 21 N and 0.5, 1.0, 1.5, 2.0 N·m to the models to analyze the joint range of motion (ROM), vertebral stress, and intervertebral disc pressure distribution characteristics under different motion conditions of the cervical spine. The ROM and stress values in the C2~C7 cervical spine of two models exhibit non-linear increases with the torque increasing during flexion, extension, lateral bending, and rotation movements. Under 21 N concentrated force and 0.5 N·m torque, the overall ROM of C2~C7 in the cervical spine of model 1 and model 2 were 8.3˚, 19.07˚, 25.14˚, 28.2˚ and 10.91˚, 20.08˚, 18.92˚ and 27.61˚, respectively under flexion, extension, lateral bending and rotation. The ROM of the two models increased by up to 21.19˚, 27.84˚, 36.83˚ and 19.08˚, 30.05˚, 38.31˚, respectively, when the torque of 1.0, 1.5 and 2.0 N·m was compared with that of 0.5 N·m. Under 21 N concentrated force and 0.5 N·m torque, the maximum stress of C2~C7 vertebrae in model 1 and model 2 were 3.19, 11.75, 5.93, 4.84 MPa and 3.96, 9.81, 6.71, 5.89 MPa in flexion, extension, lateral bending and rota-tion, respectively. Compared with 0.5 N·m, the maximum stress increases of the two models under 1.0, 1.5 and 2.0 N·m torque are 133.54%, 203.76%, 286.21% and 83.33%, 138.38% and 220.20%, respectively. The stress of intervertebral disc in children is the minimum in flexion and the maxi-mum in extension, and the stress distribution characteristics of vertebral body and intervertebral disc are basically consistent with previous studies. The ROM and stress size and distribution char-acteristics of the two children are similar, the ROM of the cervical spine of children C2~C7 is larger than that of adults, and the stress value of the vertebral body and intervertebral disc is smaller than that of adults. The difference between the cervical spine of children and that of adults should be considered in the prevention and treatment of cervical spondylosis in children.