Lenke 1 BN型特发性脊柱侧凸有限元模型的建立及有效性验证

目的 构建Lenke 1 BN型青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)三维有限元模型,并验证其有效性,为AIS生物力学仿真研究建立理想的数字化平台.方法 选择1例18岁女性Lenke 1 BN型AIS志愿者作为研究对象.取仰卧位,应用螺旋CT从T1椎体上缘至尾骨以1 mm间距进行连续扫描,获得Dicom格式CT图像539张.将CT图像导入逆向工程软件Mimics 10.01,建立包括胸-腰-骶尾椎和胸廓等结构的完整AIS三维几何模型.对模型进行几何清理,然后导入有限元前处理软件Hyper Mesh 7.0划分有限元实体单元,并参照文献添加椎间盘及韧带结构单元,生成完整的AIS三维有限元模型.参照文献赋予模型材料参数和实常数,并通过左、右Bending试验和仰卧-站立试验,对模型进行整体的有效性验证.结果 成功构建了完整的Lenke 1 BN型AIS三维非线性有限元模型,共划分节点341 228个,四面体单元1 409 929个,壳单元163 132个,线缆单元715个和杆单元149个.有限元模拟左、右Bending试验和仰卧-站立试验误差分别为8.3%和3.9%.结论 所建立的Lenke 1 BN型AIS三维有限元模型完整、逼真、可靠且有效,可用于进一步的AIS生物力学仿真研究.

Establishment and validation of 3-dimensional finite element model of Lenke 1 BN idiopathic scoliosis

Objective To set up and validate three-dimensional finite element model (FEM) of Lenke 1 BN idiopathic scoliosis based on CT images, for building ideal digitization platform for further biomechanical study. Methods An 18-year-old female Lenke 1 BN idiopathic scoliosis patient was selected as volunteer for current study. CT transverse scanning in supine position was done from T1 to caudal end in 1mm layer interval. All CT images were imported into Mimics 10.01 to form qualified AIS three-dimensional geometric model after geometry clean, including all thoraco-lumbar-sacral vertebrae and thoracic cage, which was further delivered to Hypher Mesh 7.0 to build 3d finite element AIS model by mesh partition and quality control. A variety of material parameters were given to different mesh according to references. Validation verification was done by left and right Bending test and erect-supine test. Results 1 )A complete three-dimensional finite element model of Lenke 1 BN idiopathic scoliosis was built successfully, in consist of 341 228 nodes,1 409 929 tetrahedron elements, 163 132 shell elements, 715 cable elements and 149 rod elements. 2)The convex bending Cobb's angles of PT, MT and L curve on X-ray films and finite element simulation were 14°,26° ,8° and 15° ,24°,6° respectively. The error of finite element simulation was 8.3%. 3)Erect Cobb's angles of PT, MT and L were 37°, 50°, 24° and 33°, 51°, 24° on X-ray films and by finite element simulation.Supine Cobb's angles of PT, MT and L were 29°, 43°, 22° and 27°, 42°, 22° on X-ray films and by finite element simulation. The average error of finite element simulation was 3.9%. Conclusion Lenke 1 BN idiopathic scoliosis FEM is intact, reliable and effective for further biomechanical simulation study.