A finite element analysis on crack extension on femoral neck simulated by multi-axial sideways fall based on fracture mechanics

doi:10.3969/j.issn.2095-4344.1055

Abstract

Abstract:

文章快速阅读：

文题释义：

侧方跌倒：90%以上的髋部骨折由侧方跌倒所致。后方跌倒发生髋部撞击的危险度则比侧方跌倒低10倍，表明髋部撞击力的方向可能是影响髋部骨折发生的一个重要原因。目前国外应用有限元方法研究髋部骨折较为普遍，并认为股骨颈外上侧是侧方跌倒时骨质断裂最先发生的区域。但目前骨折发生机制的分析主要通过分析静态受力分布(Von Mises应力云图)来判断应力集中部位，预测骨折发生的起始点。然而骨骼是各向异性的弹塑性材料，传统准静态有限元分析无法给出具体断裂起始点及骨折发生发展过程。

断裂力学：材料在不断负荷作用下发生微裂纹，导致材料刚度和强度等降低，微裂纹积累到一定程度就出现裂纹扩展，继而发生大面积的裂纹，进而导致材料的折断和失效。断裂是连续的，断裂力学可直接分析构件的受力和破坏过程，因此可将脆性骨折的发生过程细化为：骨密度降低-骨小梁微损伤-裂纹拓展-微骨折-骨质断裂的一个完整过程。

摘要

背景：目前骨折发生机制的分析主要通过分析静态受力分布(Von Mises应力云图)来判断应力集中部位，预测骨折发生的起始点。然而骨骼是各向异性的弹塑性材料，传统准静态有限元分析无法给出具体断裂起始点及骨折发生发展过程。因此，在骨科有限元研究领域引入断裂力学的概念是具有实际意义的。

目的：模拟不同侧方跌倒角度对股骨颈骨折裂纹扩展的影响。

方法：选取1名健康志愿者的股骨原始CT数据，导入Mimics 19.0软件，经区域增长、编辑笼罩、光滑、包裹等重建股骨近端三维有限元模型，并在Hypermesh 14.0中进行网格划分、定义材料属性、设定边界条件、加载载荷，模拟股骨中立位0°、内旋30°、外旋30°、内收30°跌倒状态等前处理，将生成的K文件导入LS-DYNA求解器中运算。

结果与结论：①股骨内收模型最早发生股骨颈断裂失效，外旋模型最迟；②4种模型的应力集中及骨质断裂均最早出现在股骨颈外上侧，内下侧继而出现裂纹并与之相融合，形成Garden Ⅱ 型骨折；③股骨颈骨折Linton角以内收模型最小，外旋模型其次，中立位模型与内旋模型差异无显著性意义(P=0.387)；④股骨颈外上侧为压力侧，内下侧为张力侧；除内收模型，其余模型的股骨颈内下侧可出现压力向张力转换的应力分布；⑤提示不同侧方跌倒角度在时间和空间上会影响股骨颈骨折裂纹扩展行为。

中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程
ORCID: 0000-0001-5241-1096(郑利钦)

Key words: 侧方跌倒, 股骨颈骨折, 裂纹扩展, 断裂力学, 有限元分析, 静态受力分布, 应力集中分布, 国家自然科学基金

CLC Number:

R445

Zheng Liqin, Lin Ziling, He Xiangxin, Sun Wentao, Li Pengfei, Chen Xinmin. A finite element analysis on crack extension on femoral neck simulated by multi-axial sideways fall based on fracture mechanics [J]. Chinese Journal of Tissue Engineering Research, 2019, 23(8): 1203-1207.

Figures/Tables 4

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