后向跌倒过程中脊柱胸腰段受力的实验及有限元研究

Experimental and finite element study on the stress of thoracolumbar spine during backward fall

中文关键词:  后向跌倒  有限元分析  胸腰椎损伤

英文关键词:Fall backward  Finite element analysis  Thoracolumbar injury

中文摘要:

  【摘要】 目的：以动力学仿真软件获取志愿者后向跌倒过程中胸腰段受力状况的运动、动力学数据，作为有限元加载条件，评估跌倒过程中脊柱局部应力情况。方法：选取1名健康志愿者（男性，27岁，175cm，70kg），随后对志愿者躯干进行CT扫描。然后，在Anybody人体建模仿真系统软件中建立骨骼肌肉模型，志愿者站立并后向倾斜30°，在无防备状态下后向摔倒构建跌倒过程中人体骨骼肌模型。根据志愿者CT数据建立并优化有限元模型，模型在施加7.5N·m力矩模拟前屈、后伸、左右侧弯及旋转范围，验证模型有效性后，将获取后向跌倒状态下着力点、应力传导方向及受力区应力值作为加载条件并赋予人体胸腰段有限元模型进行有限元分析。结果：Anybody人体建模仿真系统软件模拟后向跌倒实验中，志愿者呈无意识后向跌倒姿态，骶尾部最先着地；臀部与测力台冲击的总时间为1.14s，最大冲击力达4056N；模型以坐骨结节为力加载点，由骶尾部沿脊柱长轴向头部进行力学加载。有限元结果显示，应力经传导主要集中于T11~L2节段；在该节段中，椎体前缘平均应力达16.6MPa；上下关节突平均载荷达25.4MPa，椎板及椎弓根与椎体连接处也出现明显的应力集中，平均应力为26.2MPa。结论：后向跌倒时胸腰段所受应力较大，骨折风险较高。

英文摘要:

  【Abstract】 Objectives: To evaluate the local stress of thoracolumbar vertebra after falling by constructing real backward falling down model based on the finite element loading condition obtained from volunteers. Methods: A healthy volunteer (male, 27 years old, 175cm, and 70kg) was selected, and the torso of the volunteer was scanned by CT. Then the skeletal muscle model was established using the dynamic simulation software Anybody Modeling System. The volunteers stood at a backward tilt of 30° and fell backward to construct a human skeletal muscle model in the state of fall. The finite element model was established and optimized based on the CT data of the volunteer. Applied 7.5N·m moment to simulate the range of flexion, extension, left and right lateral bending and rotation, and validated the effectiveness of the model. The stress point, stress conduction direction and stress value in the stress area in the backward fall state were collected as loading conditions, and the finite element model of human thoracolumbar segment was given for finite element analysis. Results: In the backward fall experiment simulated by Anybody Modeling System, the volunteer fell backward unconsciously, and the sacrum was the first part to land; the total impact time between the hip and the force platform was 1.14s, and the maximum impact force was 4056N; the model took the ischial tubercle as the force loading point, and the sacral part was mechanically loaded to the upper vertebral body along the long axis of the spine. The finite element results showed that the stress conduction was mainly concentrated in the T11-L2 segment, in which the average stress at the anterior edge of the vertebral body was 16.6MPa, the average load of the upper and lower articular process was 25.4MPa, and the average stress concentration at the lamina and the connection between the pedicle and the vertebral body was 26.2MPa. Conclusions: During falling backward, there was higher stress on the thoracolumbar segment, and therefore the risk of fracture was higher.