有限元法分析不同侧方跌倒角度下股骨颈骨折裂纹扩展的断裂力学特征
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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;(2)4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GardenⅡ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。
BACKGROUND: The pathogenesis of fractures is mainly investigated by Von Mises stress nephogram to assess the stress centration region, and further predict the start part of fracture. Bone is an anisotropic elastoplastic material, so traditional static finite element analysis cannot confirm the specific start part and occurrence progress of fracture. Thereafter, fracture mechanics applied in bone finite element analysis is of great significance.OBJECTIVE: To simulate the crack extension on femoral neck induced by multi-axial sideways fall. METHODS: CT image data of a healthy volunteer's femur were collected and imported to Mimics 19.0 software. After region growing, cavity filling, editing, smoothing and wrapping, a three-dimensional finite element model of proximal femur was established. The primary model was imported in Hypermesh 14.0 for meshing, defining material properties, failure parameters, interfacial properties. Load and force boundary constraints simulating multi-axial sideways fall were also simulated. The multi-axial sideways fall was set as rotation 0°, internal rotation 30°, external rotation 30° and adduction 30°. The integrated K files were finally calculated in LS-DYNA. RESULTS AND CONCLUSION:(1) Adducent femur was the earliest to crack on femoral neck while the external rotation femur was the latest.(2) Garden type II fractures were simulated in all objects on which crack occurred firstly on the superior of femoral neck fusing with the inferior breakage.(3) The neutral femur showed no significance with internal rotation femur(P=0.387) in Linton angle, while adducent femur showed the smallest Linton angle, followed by external rotation femur.(4) Tensile and compressive stresses, respectively, were found on the inferior and superior of femoral neck in Von Mises distribution, whereas the state of stress was convertible from tensile to compressive at the beginning of impact in all femurs except adducent femur on the inferior of femoral neck.(5) To conclude, different axial loadings on femoral head during sideways fall influence the crack extension behavior on femoral neck.
BACKGROUND: The pathogenesis of fractures is mainly investigated by Von Mises stress nephogram to assess the stress centration region, and further predict the start part of fracture. Bone is an anisotropic elastoplastic material, so traditional static finite element analysis cannot confirm the specific start part and occurrence progress of fracture. Thereafter, fracture mechanics applied in bone finite element analysis is of great significance.OBJECTIVE: To simulate the crack extension on femoral neck induced by multi-axial sideways fall. METHODS: CT image data of a healthy volunteer's femur were collected and imported to Mimics 19.0 software. After region growing, cavity filling, editing, smoothing and wrapping, a three-dimensional finite element model of proximal femur was established. The primary model was imported in Hypermesh 14.0 for meshing, defining material properties, failure parameters, interfacial properties. Load and force boundary constraints simulating multi-axial sideways fall were also simulated. The multi-axial sideways fall was set as rotation 0°, internal rotation 30°, external rotation 30° and adduction 30°. The integrated K files were finally calculated in LS-DYNA. RESULTS AND CONCLUSION:(1) Adducent femur was the earliest to crack on femoral neck while the external rotation femur was the latest.(2) Garden type II fractures were simulated in all objects on which crack occurred firstly on the superior of femoral neck fusing with the inferior breakage.(3) The neutral femur showed no significance with internal rotation femur(P=0.387) in Linton angle, while adducent femur showed the smallest Linton angle, followed by external rotation femur.(4) Tensile and compressive stresses, respectively, were found on the inferior and superior of femoral neck in Von Mises distribution, whereas the state of stress was convertible from tensile to compressive at the beginning of impact in all femurs except adducent femur on the inferior of femoral neck.(5) To conclude, different axial loadings on femoral head during sideways fall influence the crack extension behavior on femoral neck.
引文
[1]Grisso JA, Kelsey JL, Strom BL, et al. Risk factors for falls as a cause of hip fracture in women. The Northeast Hip Fracture Study Group. N Engl J Med. 1991;324(19):1326-1331.
[2]Crenshaw JR, Bernhardt KA, Achenbach SJ, et al. The circumstances, orientations, and impact locations of falls in community-dwelling older women. Arch Gerontol Geriatr. 2017;73(7):240-247.
[3]Yang Y, Mackey DC, Liu-Ambrose T, et al. Risk factors for hip impact during real-life falls captured on video in long-term care.Osteoporos Int. 2016;27(2):537-547.
[4]de Bakker PM, Manske SL, Ebacher V, et al. During sideways falls proximal femur fractures initiate in the superolateral cortex:Evidence from high-speed video of simulated fractures. J Biomech. 2009;42(12):1917-1925.
[5]Marco M, Giner E, Larraínzar-Garijo R, et al. Numerical Modelling of Femur Fracture and Experimental Validation Using Bone Simulant. Ann Biomed Eng. 2017;45(10):2395-2408.
[6]董谢平,张琳琳,何剑颖,等.髋保护器防护髋部骨折的有限元建模与分析[J].中国矫形外科杂志,2011,19(18):1537-1541.
[7]袁高翔,张伟滨.有限元分析在骨骼肌肉系统模型材料特性研究中的应用[J].国际骨科学杂志,2011,32(6):352-355.
[8]李鹏飞,杜根发,林梓凌,等.基于LS-DYNA模拟老年股骨颈骨折的有限元分析[J].中国组织工程研究,2016,22(44):6606-6611.
[9]孙文涛,林梓凌,李凡,等.基于Hypermesh/LS-DYNA仿真股骨干中上1/3骨折的断裂分析[J].广东医学,2017,38(16):2481-2483.
[10]何祥鑫,李鹏飞,林梓凌,等.基于有限元分析法的老年粗隆间骨折建模仿真[J].中国医药导报,2017,14(24):88-91,封3.
[11]Nishiyama KK, Gilchrist S, Guy P, et al. Proximal femur bone strength estimated by a computationally fast finite element analysis in a sideways fall configuration. J Biomech. 2013;46(7):1231-1236.
[12]Wakao N, Harada A, Matsui Y, et al. The effect of impact direction on the fracture load of osteoporotic proximal femurs. Med Eng Phys. 2009;31(9):1134-1139.
[13]Hayes WC, Piazza SJ, Zysset PK. Biomechanics of fracture risk prediction of the hip and spine by quantitative computed tomography. Radiol Clin North Am. 1991;29(1):1-18.
[14]彭李华,陈世荣,唐进,等.骨质疏松股骨三维有限元模型的建立[J].中国组织工程研究与临床康复,2010,14(9):1545-1548.
[15]Rieger R, Auregan JC, Hoc T. Micro-finite-element method to assess elastic properties of trabecular bone at micro-and macroscopic level. Morphologie. 2018;102(336):12-20.
[16]Gomez-Benito MJ, Garcia-Aznar JM, Doblare M. Finite element prediction of proximal femoral fracture patterns under different loads. J Biomech Eng. 2005;127(1):9-14.
[17]Majumder S, Roychowdhury A, Pal S. Effects of body configuration on pelvic injury in backward fall simulation using 3D finite element models of pelvis–femur–soft tissue complex. J Biomech. 2009;42(10):1475-1482.
[18]Robinovitch SN, Inkster L, Maurer J, et al. Strategies for avoiding hip impact during sideways falls. J Bone Miner Res. 2003;18(7):1267-1273.
[19]Wang Q, Teo JW, Ghasem-Zadeh A, et al. Women and men with hip fractures have a longer femoral neck moment arm and greater impact load in a sideways fall. Osteoporos Int. 2009;20(7):1151-1156.
[20]Zebaze RM, Jones A, Knackstedt M, et al. Construction of the femoral neck during growth determines its strength in old age. J Bone Miner Res. 2007;22(7):1055-1061.
[21]Mayhew PM, Thomas CD, Clement JG, et al. Relation between age, femoral neck cortical stability, and hip fracture risk. Lancet.2005;366(9480):129-135.
[22]Faisal TR, Luo Y. Study of the variations of fall induced hip fracture risk between right and left femurs using CT-based FEA.Biomed Eng Online. 2017;16(1):116-132.
[23]Thomas CDL, Mayhew PM, Power J, et al. Femoral Neck Trabecular Bone:Loss With Aging and Role in Preventing Fracture. J Bone Miner Res. 2009;24(11):1808-1818.
[24]Sarai T, Tokumoto A. Dynamic finite element analysis of impulsive stress waves propagating from the greater trochanter of the femur by a sideways fall. Acta Med Okayama. 2015;69(3):165-171.
[25]孙培栋.侧方跌倒高度及髋保护器对髋部冲击影响的实验及有限元分析[D].广州:南方医科大学,2012.
[26]Szivek JA, Benjamin JB, Anderson PL. An experimental method for the application of lateral muscle loading and its effect on femoral strain distributions. Med Eng Phys. 2000;22(2):109-116.
[2]Crenshaw JR, Bernhardt KA, Achenbach SJ, et al. The circumstances, orientations, and impact locations of falls in community-dwelling older women. Arch Gerontol Geriatr. 2017;73(7):240-247.
[3]Yang Y, Mackey DC, Liu-Ambrose T, et al. Risk factors for hip impact during real-life falls captured on video in long-term care.Osteoporos Int. 2016;27(2):537-547.
[4]de Bakker PM, Manske SL, Ebacher V, et al. During sideways falls proximal femur fractures initiate in the superolateral cortex:Evidence from high-speed video of simulated fractures. J Biomech. 2009;42(12):1917-1925.
[5]Marco M, Giner E, Larraínzar-Garijo R, et al. Numerical Modelling of Femur Fracture and Experimental Validation Using Bone Simulant. Ann Biomed Eng. 2017;45(10):2395-2408.
[6]董谢平,张琳琳,何剑颖,等.髋保护器防护髋部骨折的有限元建模与分析[J].中国矫形外科杂志,2011,19(18):1537-1541.
[7]袁高翔,张伟滨.有限元分析在骨骼肌肉系统模型材料特性研究中的应用[J].国际骨科学杂志,2011,32(6):352-355.
[8]李鹏飞,杜根发,林梓凌,等.基于LS-DYNA模拟老年股骨颈骨折的有限元分析[J].中国组织工程研究,2016,22(44):6606-6611.
[9]孙文涛,林梓凌,李凡,等.基于Hypermesh/LS-DYNA仿真股骨干中上1/3骨折的断裂分析[J].广东医学,2017,38(16):2481-2483.
[10]何祥鑫,李鹏飞,林梓凌,等.基于有限元分析法的老年粗隆间骨折建模仿真[J].中国医药导报,2017,14(24):88-91,封3.
[11]Nishiyama KK, Gilchrist S, Guy P, et al. Proximal femur bone strength estimated by a computationally fast finite element analysis in a sideways fall configuration. J Biomech. 2013;46(7):1231-1236.
[12]Wakao N, Harada A, Matsui Y, et al. The effect of impact direction on the fracture load of osteoporotic proximal femurs. Med Eng Phys. 2009;31(9):1134-1139.
[13]Hayes WC, Piazza SJ, Zysset PK. Biomechanics of fracture risk prediction of the hip and spine by quantitative computed tomography. Radiol Clin North Am. 1991;29(1):1-18.
[14]彭李华,陈世荣,唐进,等.骨质疏松股骨三维有限元模型的建立[J].中国组织工程研究与临床康复,2010,14(9):1545-1548.
[15]Rieger R, Auregan JC, Hoc T. Micro-finite-element method to assess elastic properties of trabecular bone at micro-and macroscopic level. Morphologie. 2018;102(336):12-20.
[16]Gomez-Benito MJ, Garcia-Aznar JM, Doblare M. Finite element prediction of proximal femoral fracture patterns under different loads. J Biomech Eng. 2005;127(1):9-14.
[17]Majumder S, Roychowdhury A, Pal S. Effects of body configuration on pelvic injury in backward fall simulation using 3D finite element models of pelvis–femur–soft tissue complex. J Biomech. 2009;42(10):1475-1482.
[18]Robinovitch SN, Inkster L, Maurer J, et al. Strategies for avoiding hip impact during sideways falls. J Bone Miner Res. 2003;18(7):1267-1273.
[19]Wang Q, Teo JW, Ghasem-Zadeh A, et al. Women and men with hip fractures have a longer femoral neck moment arm and greater impact load in a sideways fall. Osteoporos Int. 2009;20(7):1151-1156.
[20]Zebaze RM, Jones A, Knackstedt M, et al. Construction of the femoral neck during growth determines its strength in old age. J Bone Miner Res. 2007;22(7):1055-1061.
[21]Mayhew PM, Thomas CD, Clement JG, et al. Relation between age, femoral neck cortical stability, and hip fracture risk. Lancet.2005;366(9480):129-135.
[22]Faisal TR, Luo Y. Study of the variations of fall induced hip fracture risk between right and left femurs using CT-based FEA.Biomed Eng Online. 2017;16(1):116-132.
[23]Thomas CDL, Mayhew PM, Power J, et al. Femoral Neck Trabecular Bone:Loss With Aging and Role in Preventing Fracture. J Bone Miner Res. 2009;24(11):1808-1818.
[24]Sarai T, Tokumoto A. Dynamic finite element analysis of impulsive stress waves propagating from the greater trochanter of the femur by a sideways fall. Acta Med Okayama. 2015;69(3):165-171.
[25]孙培栋.侧方跌倒高度及髋保护器对髋部冲击影响的实验及有限元分析[D].广州:南方医科大学,2012.
[26]Szivek JA, Benjamin JB, Anderson PL. An experimental method for the application of lateral muscle loading and its effect on femoral strain distributions. Med Eng Phys. 2000;22(2):109-116.