股骨有限元模型材料属性分配梯度的优化分析

优化分析股骨有限元模型材料属性分配梯度,从而得到相对准确且经济的划分层数,为CT灰度值赋值法在医学有限元研究领域的应用奠定理论基础。首先选取1名成人志愿者的股骨进行CT密扫,将获取的DICOM格式CT序列医学图像数据输入Mimics中,并建构出3D渲染模型。在此基础上通过SolidWorks对模型实体化,导入HyperMesh进行体网格划分,再返回Mimics中,选择2、4、5、10、50、100、200、400层等8种梯度进行赋材质,最后将有限元模型在ABAQUS软件中设定工况,并实施仿真分析;同时构建股骨近端有限元模型,通过与文献数据对比分析来验证其有效性。结果表明,研究所构建的股骨有限元模型的应力、应变水平与有关文献的实验结果一致,其有效性得到充分验证。在材料属性分配梯度的优化分析中,2、4、5、400层材料属性时的应力与其他层材料属性相比具有显著性差异(P＜0.05),同时这4组材料属性之间的应力也具有显著性差异(P＜0.05),而10、50、100、200层的材料属性间应力则没有明显的结果偏差。10层材料属性既能提高运算速度,节省运算量,又能保证运算结果的精准性;CT灰度值赋值法适用于临床个体化快速有限元仿真分析。     

Finite Element Analysis on the Diagnosis and Treatment of Osteonecrosis of Femoral Head

Developing the radiographic images from two to three-dimensional, finite element analysis(FEA) technology can set up the model, predicting diagnosis, treatment design, as well as surgical plan. FEA provides an accurate three-dimensional finite element biomechanical study in osteonecrosis of femoral head(ONFH). The papers in the latest 5 years related to femoral head osteonecrosis and finite element analysis application are concentrated on. We summarize the latest research progress and problems, including the applied research carried out in the femoral head osteonecrosis clinical cases,innovational skills, so as to point out the direction of future research in FEA.     

髋臼发育不良性髋关节的三维有限元非线性接触压力分析

目的 从生物力学角度探讨髋臼覆盖程度(CE角)在髋臼发育不良引起的髋关节继发性骨关节炎中的作用。方法 建立正常、髋臼发育不良及髋臼过渡覆盖的髋关节三维有限元模型,应用非线性接触压力分析方法,观察髋臼发育不良性髋关节的关节软骨接触压力及软骨下骨应力分布。结果在所有的模型中,接触压力及应力均发生在股骨头最上部及与其相对应的髋臼顶穹部。在髋臼发育不良的模型中,另有过度不正常的接触压力发生在髋臼的后上缘区域。随着CE角的减小,接触压力和峰应力明显增高,接触面积下降。当CE角大于30°,压力分布类型及接触压力和峰应力改变不明显。结论髋臼覆盖程度降低所导致的生物力学改变在髋关节继发性骨关节炎中起重要作用。     

Relationships Between Pulmonary Function and Composite Indices of Femoral Neck Strength in Korean Men (KNHANES IV)

BackgroundDespite the close relationship between osteoporosis and chronic pulmonary diseases, few studies have evaluated relationships between pulmonary functions and bone quality. We investigated associations between pulmonary function test results and femoral neck strength indices (SIs) in Korean men.MethodsThis population-based, cross-sectional study was conducted using data from the Korea National Health and Nutrition Examination Survey IV on 936 men aged ≥ 19 years. Pulmonary functions (forced vital capacity [FVC] and forced expiratory volume in one second [FEV₁]) were measured using a dry rolling seal spirometer. Femoral neck SIs, relative to load, were calculated by hip dual-energy X-ray absorptiometry for compression strength index (CSI), bending strength index (BSI), and impact strength index (ISI).ResultsThe 443 (47.3%) of the 936 men were current smokers. FVC, FVC percentage with respect to the expected normal value, FEV₁, and FEV₁ percentage with respect to the expected normal value (FEV₁p) were positively associated with CSI and BSI after adjusting for confounders, including smoking history (β = 0.003–0.223, P = 0.005–0.036). FEV₁ and FEV₁p were positively associated with ISI (β = 0.000–0.014, P = 0.010–0.025). Of components of femoral neck SIs, bone mineral density was correlated with FEV₁ and FEV₁p (β = 0.001–0.037, P = 0.017–0.019). After adjusting for all confounders, all femoral neck SIs increased with FVC quintiles (P for trends = 0.001–0.012), and CSI and BSI increased with FEV₁ quintiles (P for trends = 0.034–0.043).ConclusionReduced pulmonary function was correlated with reduced femoral neck strength, even after adjusting for smoking history in Korean men. Femoral neck SIs might be useful tools for evaluating bone health in men with reduced pulmonary function.     

LISS钢板治疗股骨远端骨折有限元建模及分析

目的 建立LISS-DF治疗股骨远端骨折近端螺钉不同单双皮质固定的三维有限元模型,并进行初步生物力学分析.方法 提取CT图片相关数据,利用自行编写程序生成命令流文件,建立完整股骨以及16个不同LISS-DF治疗股骨远端AO分型33-A3型骨折的实体模型(钢板和股骨不接触、螺钉分别固定于钢板和股骨),进行网格划分.分析不同载荷作用下完整股骨和LISS钢板近端螺钉全双皮质固定治疗骨折的模型受力状况.结果 建立了相关的有限元模型.不同载荷作用下,LISS钢板近端螺钉全双皮质固定模型和完整股骨的应力集中均位于股骨颈内侧和股骨干外侧中下1/3处.相同载荷作用下,LISS钢板近端螺钉全双皮质固定模型的股骨颈部最大等效应力值略减小,股骨干最大等效应力值明显减小.结论 研究建立的三维有限元模型,为应用LISS治疗股骨骨折的生物力学分析提供了良好的实验平台和基础.从生物力学角度而言,LISS-DF近端螺钉全双皮质固定为治疗股骨远端复杂骨折的有效方法.     

人体真实形状手指内的血液流动和温度分布的有限元分析

本研究的目的是要考察人体末梢的血流变化及温度调节特性. 分别对上肢大血管内血液流动及手指的传热特性进行分析并建立了数学模型.采用一维非线性脉动流体力学模型模拟大血管内的血液流动,采用描述多孔介质内流体流动的Darcy模型模拟组织内血液流动, 而用多孔介质内的能量方程描述组织内的传热特性.同时利用基于图像的建模方法,由手指的MRI系列图像建立了中指的计算机模型并生成了有限元网格.通过分析,得到人体真实形状手指内的血液流动和温度分布,并与由红外热像仪测得的结果进行了比较.比较结果显示,手指的皮肤温度变化趋势与实测结果相同,说明该模拟分析系统能够较好地分析上肢血流及末梢的传热特性.     

Cell Area and Strut Distribution Changes of Bent Coronary Stents： A Finite Element Analysis

Coronary stents are metal coils or mesh tubes delivered to blocked vessels through catheters, whic Recently, special drugs h are expanded by balloons to reopen and scaffold target vessels. are carried by stents （drug-eluting stents） to further reduce instent restenosis rate after stenting procedure. However, continual study on biomechanical characteristics of stents is necessary provide a more suitable drug loading for better interactions between stents and tissue, or to platform for drug-eluting stents. The purpose of this paper is to show how finite element methods can be used to study cell area and strut distribution changes of bent coronary stents. A same bending deformation was applied to two commercial coronary stent models by a rigid curved vessel. Results show that the stent design influenced the changes of cell area and strut distribution under bending situation. The stent with links had more cell area changes at outer curvature, and the stent with peak-peak （ 〉 〈 ） strut design could have strut contact and overlapping at inner curvature. In conclusion, this finite element method can be used to study and compare cell area and strut distribution changes of bent stents, and to provide a convenient tool for designers in testing and improving biomechanical characteristics of new stents.     

Relations Between Components of Impedance Cardiogram Analyzed by Means of Finite Element Model and Sensitivity Theorem

The main aim of the study is to establish a relation between different sources of Impedance cardiogram (ICG) as function of spatial distribution of conductivity. A three-dimensional model of a human thorax using the finite element method has been constructed. The model includes 35 horizontal layers consisting of up to 519 pentahedral elements that are automatically divided into tetrahedral ones before calculating the potential distribution. Electrode array configuration proposed by Kubicek et al. (Aerosp. Med. 37: 1208–1212, 1996) has been studied. A relationship proposed by Geselowitz (IEEE Trans. Biomed. Eng. 18: 38–41, 1971) has been used to calculate the sensitivity of the examined electrode array to conductivity changes inside the thorax. This relationship has allowed for the calculation of the contributions to ICG from spatially separated sources when modeling all changes in conductivity simultaneously. It has been confirmed that the main contributions to ICG signal come from ventricles, atria, aorta, and lungs. The relations between these components have been found to be dependent nonlinearly on spatial conductivity distribution. As a result, reliable and reproducible measurements of stroke volume (SV) using ICG are impossible. Nevertheless, ICG can be used to monitor relative changes of SV in all cases where the spatial distribution of conductivity and geometry of the subject, during the examination, is preserved. However, it does not mean that the accuracy of SV measurement will be the same in all these cases. © 2000 Biomedical Engineering Society. PAC00: 8719Hh, 8719Nn, 8437+q, 0270Dh     

Finite Element Analysis of the Current-Density and Electric Field Generated by Metal Microelectrodes

Electrical stimulation via implanted microelectrodes permits excitation of small, highly localized populations of neurons, and allows access to features of neuronal organization that are not accessible with larger electrodes implanted on the surface of the brain or spinal cord. As a result there are a wide range of potential applications for the use of microelectrodes in neural engineering. However, little is known about the current-density and electric field generated by microelectrodes. The objectives of this project were to answer three fundamental questions regarding electrical stimulation with metal microelectrodes using geometrically and electrically accurate finite elements models. First, what is the spatial distribution of the current density over the surface of the electrode? Second, how do alterations in the electrode geometry effect neural excitation? Third, under what conditions can an electrode of finite size be modeled as a point source? Analysis of the models showed that the current density was concentrated at the tip of the microelectrode and at the electrode–insulation interface. Changing the surface area of the electrode, radius of curvature of the electrode tip, or applying a resistive coating to the electrode surface altered the current-density distribution on the surface of the electrode. Changes in the electrode geometry had little effect on neural excitation patterns, and modeling the electric field generated by sharply tipped microelectrodes using a theoretical point source was valid for distances >～ 50μm from the electrode tip. The results of this study suggest that a nearly uniform current-density distribution along the surface of the electrode can be achieved using a relatively large surface area electrode μ00--1000μm²), with a relatively blunt tip (3–6 μm radius of curvature), in combination with～mμ～ 1μm) moderately resistive ～( ～ 50Ωm). © 2001 Biomedical Engineering Society. PAC01: 8719Nn, 0270Dh, 8780-y, 8710+e     

模拟股骨颈骨折外固定器固定结构模型三维有限元计算与应力分布实验研究

报道了模拟股骨颈骨折，以李治罡设计的股骨颈骨折外固定器进行外固定。模拟作用于股骨头不同方向的压力进行三维有限元分析。得出了肌骨颈、股骨干、外固定钢针等各节点的主应力σ1、σ3和位移值。还以应变电测技术与原理对模拟股骨颈骨折外固定器固定后进行应变电测量，测量了股骨干、外固定器钢针等各测点的应变、得出了各测点的应力值。计算与实验结果表明股骨颈骨折外固定器的设计符合生物力学原理，具有较好的强度、刚度和稳定性。     

The Local Matrix Distribution and the Functional Development of Tissue Engineered Cartilage,a Finite Element Study

Assessment of the functionality of tissue engineered cartilage constructs is hampered by the lack of correlation between global measurements of extra cellular matrix constituents and the global mechanical properties. Based on patterns of matrix deposition around individual cells, it has been hypothesized previously, that mechanical functionality arises when contact occurs between zones of matrix associated with individual cells. The objective of this study is to determine whether the local distribution of newly synthesized extracellular matrix components contributes to the evolution of the mechanical properties of tissue engineered cartilage constructs. A computational homogenization approach was adopted, based on the concept of a periodic representative volume element. Local transport and immobilization of newly synthesized matrix components were described. Mechanical properties were taken dependent on the local matrix concentration and subsequently the global aggregate modulus and hydraulic permeability were derived. The transport parameters were varied to assess the effect of the evolving matrix distribution during culture. The results indicate that the overall stiffness and permeability are to a large extent insensitive to differences in local matrix distribution. This emphasizes the need for caution in the visual interpretation of tissue functionality from histology and underlines the importance of complementary measurements of the matrixs intrinsic molecular organization.     

用三维重建和有限元方法对人体心脏进行力学分析

目的　建立人体心脏的三维几何模型和有限元网格模型，进行有限元仿真计算。方法　利用可视化人体心脏数据集，通过3D-DOCTOR软件和SOLIDWORKS软件重建心脏外形和内腔的三维结构数据，以STEP格式导入ABAQUS有限元软件形成网格模型。在有限元网格模型的基础上进行心脏自振频率、内腔血压等载荷情况下的力学性能分析。结果　建立了一个数字化心脏可视模型。能够反映心脏三维形状和内腔结构；得到了心脏内腔的大致容积；反映了心脏心肌不同区域的不同性质；得到了心脏3个方向的自振频率和振型，以及内腔血压下的应力分布。结论　建立了可视化三维心脏的几何和网格模型，反映了心脏的外形和内腔。利用有限元分析方法，能够为心脏的生物力学分析提供可视化的数值仿真平台。     

基于有限元模型分析不同蹬冰角度足踝部应力分布差异

目的 模拟仿真不同蹬冰角度足踝部的应力,通过优化分析得到合理的蹬冰角度与足踝部应力的定量关系。 方法 建立冰球鞋-足踝耦合有限元模型,三维拍摄获取冰球运动员的运动学参数进行模型验证与约束,计算对比 分析不同角度蹬冰动作的足踝部应力,构建多目标优化函数模型。 结果 在相同蹬冰角度下,胫腓骨应力最大,距 下关节应力次之,第 1 跖趾关节应力较小,足底筋膜应力最小。 随着蹬冰角度的减小,足踝部应力单调递增,胫腓 骨和足底筋膜应力变化幅度大,距下关节和第 1 跖趾关节应力变化幅度较小。 结论 在冰球运动启动阶段蹬冰过 程中,蹬冰角度与足踝不同部位应力呈反比例关系。 最佳蹬冰角度取决于对滑冰速度的期待值,如果给定速度与 应力承受之间的偏好系数,可通过优化方法计算出最优蹬冰角度。     

种植体深度和加载方向对下颌骨应力分布影响的三维有限元分析

目的分析下颌骨种植体种植深度和加载方向对周围骨组织的应力分布影响，为临床种植应用提供参考。方法CT扫描一位第一磨牙缺失的健康女性下颌骨，运用MIMICS图像重建其几何结构，ADINA建立下颌骨及种植体平齐0mm、高于1mm、低于-1mm骨界面三种有限元模型，分析比较该模型在垂直和颊舌向两种加载方式下周围骨组织内的应力分布。结果两种加载方式下三种模型相比，最大应力出现的部位没有明显变化，但数值发生了很大变化，以低于骨界面-1mm模型数值最大，高于骨界面1mm模型最小。颊舌向与垂直向加载相比，三种模型均呈现颊舌向数值明显高的态势。结论CT扫描最大限度地忠实于个性化的解剖结构，种植体种植深度和加载方向对骨组织内的应力分布有重要影响，本文结果将为临床种植技术提供一定的理论参考。     

三维颅骨模型的建立和有限元及实验应力分析的研究

观察颅骨表面的应力分布情况,探索快速建立完整颅骨三维模型并进行有限元分析的方法。取两具新鲜颅骨进行多层螺旋CT扫描,利用专业医学建模软件完成三维重建,并将生成的三维模型导入ANSYS中进行有限元分析。用电测法测试撞击时颅骨表面的应变情况,运用实验应力分析的理论,得到了颅骨表面主应力的大小。为临床提供一定的理论依据。     

虚拟中国人足底韧带结构失效后的足弓负荷机制研究

目的　建立虚拟中国人的足内侧纵弓与外侧纵弓的有限元模型,研究跖腱膜松解术或足底韧带损伤后足骨与内在肌群的生物力学特性,探讨骨性结构、足底韧带、足底腱膜、足底固有肌群之间的协调作用机制。方法　采用虚拟中国人“女性1号”CT图像和MRI图像;采用非线性有限元方法进行足弓术后或韧带损伤后的平衡直立负荷状态仿真;并应用足底固有肌群的3种被动张力（微弱、适度、强烈）模拟术后或韧带损伤后的肌肉状态。结果　建立了虚拟中国人“女性1号”足内侧纵弓第2跖列与外侧纵弓第5跖列的生物力学有限元模型,计算得到内侧纵弓和外侧纵弓在平衡直立时,韧带损伤时,固有肌群活动时的张应力矢量图、压应力矢量图和von Mises应力整体分布数据。结论　跖腱膜松解术和足底韧带损伤等增加了足纵弓von Mises应力峰值,改变了张应力与压应力的流向;而足底固有肌活动的被动张力能降低足纵弓von Mises应力集中程度,调节张应力、压应力矢量接近平衡状态,减小了并发骨折和腱炎的危险性。骨性结构、韧带、腱膜、固有肌群的内在应力具有定量的相互调节功能。     

利用有限元分析爱惜邦线缝合固定与带线锚钉

目的 利用有限元方法对比分析爱惜邦线缝合固定与带线锚钉缝合固定髌骨下极骨折的生物力学稳定性。方法 选取1名健康成年志愿者的膝关节CT图像,建立髌骨下极骨折模型,并在此基础上建立5#爱惜邦线、带线锚钉骨折固定三维模型。其中,模型1采用5#爱惜邦线独立间断垂直缝合技术固定髌骨下极骨折,模型2在模型1基础上将两端爱惜邦尾线从髌腱下方连续锁边缝合至对侧骨折近端并收紧打结,模型3采用锚钉技术固定。分析在不同屈膝角度下各骨折固定模型的应力和位移分布。结果 在0°~90°范围内,随着屈膝角度增加,最大应力和最大位移也随之增大。在同一屈膝角度下,带线锚钉固定方式的应力水平最高,爱惜邦线固定联合锁边缝合方式的应力水平最低且应力分布最均匀;单纯爱惜邦线缝合的位移形变量最大,带线锚钉固定方式的位移形变量最小。结论 爱惜邦线缝合后加以髌腱周围的锁边缝合最大位移相对适中,且最大应力也相对较小,是临床中固定髌骨下极骨折的可靠方法。     

Change of Distribution and Timing of Bite Force after Botulinum Toxin Type A Injection Evaluated by a Computerized Occlusion Analysis System

Purpose

The aim of this study was to determine the force distribution and pattern of mastication after injection of botulinum toxin type A (BTX-A) into both masseter muscles. The hypothesis to be tested was that the difference between right and left balance of occlusal force diminishes over time following BTX-A injection.

Materials and Methods

Fifteen patients were submitted to BTX-A injection therapy for subjective masseter hypertrophy. A total of 25 U of BTX-A (50 U in total) was injected into two points located 1 cm apart at the center of the lower one-third of both masseter muscles. All patients were examined using the T-Scan occlusion analysis system before and 4, 8, 12, and 24 weeks after BTX-A injection.

Results

A significant change in force balance was found between the right and left sides over time and the difference between the two sides decreased with the time post-injection, reaching a minimum at 12 weeks. Comparison of the force balance between the anterior and posterior occlusions revealed no significant difference at any of the time points. The occlusion and disclusion times (right and left sides) did not differ significantly with time since BTX-A injection.

Conclusion

A decline in the difference in the clenching force between the left and right sides was found with increasing time up to 12 weeks following BTX-A injection.     

Covariation Between Midline Cranial Base,Lateral Basicranium,and Face in Modern Humans and Chimpanzees: A 3D Geometric Morphometric Analysis

Previous studies showed that in modern humans the basicranium is formed of two modules: the midline cranial base and the lateral basicranium which are integrated with the face in very different ways. The study of the relationship between these structures is of prime interest in the context of hominids craniofacial evolutionary history. In this study, we aim to test if the relationship between the midline cranial base and the face on one hand and the lateral basicranium and the face on the other hand are qualitatively and quantitatively different in modern humans and chimpanzees: two phylogenetically close but morphologically different hominids. This work is performed using three‐dimensional (3D) landmarks to take into account the face and basicranium 3D shape. Modern humans and chimpanzees both exhibit a significant relationship between lateral basicranium and face, and a nonsignificant relationship between midline cranial base and face. However, the patterns of integration are different for the two species. These results underscore the essential role of the lateral basicranial shape in the setting of the facial morphology in modern humans and chimpanzees. The important differences in the patterns of integration may be related to the genetic, developmental, and functional requirements of each taxon, acquired along their respective evolution. From a common, tight, relationship between lateral basicranium, and face, each taxon may develop different patterns of integration in order to adapt to particular functions and morphologies. Anat Rec, 296:568–579, 2013. © 2013 Wiley Periodicals, Inc.     

LISS-DF近端螺钉不同固定方式的有限元分析

目的 研究LISS-DF治疗股骨远端骨折近端螺钉不同固定方式对应力分布规律的影响,寻找符合生物力学原理的固定方式,为临床应用提供理论依据.方法 在ANSYS9.0软件中建立LISS-DF钢板固定股骨远端骨折(AO/OTA33-A3型)的实体模型和有限元模型.在近端螺钉不同单、双皮质固定方式下,通过模拟生理应力做轴向加载实验并进行有限元计算和分析.结果 1、3孔单2、4孔双皮质固定时,近端螺钉最大应力值在不同固定方式中最小为24.21975Mpa,位移值为0.131424um与其它固定方式相当且均较小,说明该固定方式可以取得较好的力学效果.结论 近端螺钉靠近骨折端处双皮质固定,其余螺钉间隔单双皮质固定时,可以减少应力集中现象,得到更好的把持力,使固定更牢固,从而降低固定失败的风险性.