生物硬组织材料力学研究方法进展

研究生物硬组织材料的力学性质对于预防和治疗骨科和口腔疾病具有重要意义。同时,经过长期的进化,生物材料具有独特的力学性质,研究这些材料的结构与力学性质可以为工程材料的设计提供解决方案。与工程材料不同,生物材料的力学研究需要采用特殊的方法来准确描述其力学性质。本文针对生物硬组织材料力学性质的研究方法进行综述,包括生物硬组织材料的常规力学实验方法、断裂力学和压痕测试技术,以及微观和宏观力学数值模拟技术。     

胎儿臂丛神经上干粘弹性实验研究

研究了 30具新鲜胎儿尸体臂丛神经上干的拉伸力学性质和粘弹性力学性质 ,对臂丛神经上干进行单向拉伸实验 ,得出了破坏载荷、强度极限、最大应变。对臂丛神经上干进行应力松弛、蠕变实验 ,得出了应力松弛、蠕变实验数据和曲线。对实验数据进行归一化处理 ,得出了归一化应力松弛函数、蠕变函数。以回归分析的方法处理实验数据 ,得出回归系数 ,很好地拟合了实验曲线。实验结果表明 6～ 7月龄胎儿臂丛神经上干的破坏载荷、强度极限、最大应变小于 8月龄以上的胎儿。男女胎儿臂丛神经之间拉伸力学性质差异不显著 ,低月龄胎儿臂丛神经 72 0 0S应力松弛量大于高月龄组 ,蠕变量差异不显著     

微吸管技术在动脉力学性质研究中的应用

动脉力学性质的研究对于动脉正常生理特性的分析和病理状态下性状改变的研究有着重要意义。以往的研究多采用以液体或气体给动脉加压或轴向拉伸等手段，揭示了动脉轴向、周向和径向的力学特性。在本文中，我们用微吸管给动脉施加负压使之变形的技术对动脉的弹性面积压缩性质进行了研究。以兔的胸主动脉为样本进行的实验表明动脉的表面积在微吸管负压作用下的变化与所加负压值可由指数关系Ｐ＝Ｋ（ｅｃａ－１）来拟合，其中Ｋ值反映了动脉壁的弹性面积压缩能力，称为弹性面积压缩模量，实验结果表明其正常值在５～１７ｋＰａ之间，而病态（动脉粥样硬化）下在３～１０ｋＰａ之间。实验证明了微吸管技术用于动脉力学实验的可行性，为在体血管力学性质的研究提供了有价值的技术手段。     

大鼠臂丛神经的蠕变特性

背景:臂丛神经损伤缝合吻接有必要了解臂丛神经蠕变力学特性。以往的研究多以臂丛神经的单项拉伸力学性质研究居多,关于臂丛神经蠕变黏弹性力学性质的研究鲜有报道。目的:以函数为研究方式观察分析实验动物臂丛神经的蠕变力学特性,为临床提供蠕变力学特性参数。方法:采用日本岛津电子万能试验机对SD大鼠臂丛神经进行蠕变实验。蠕变实验应力增加速度为0.01GPa/s,实验设定时间为7200s,采集100个实验数据,以归一化分析的方法处理实验数据。结果与结论:大鼠臂丛神经试样7200s蠕变为5.6%。蠕变最初600s变化较快,之后应变缓慢上升,达到7200s曲线基本平衡。结果表明蠕变曲线是以指数关系变化的,臂丛神经具有黏弹性蠕变力学特性。     

前交叉韧带及其替代物粘弹性性质的实验研究

本研究采用新鲜成人膝关节标本，对前交叉韧带及其转换替代物（髌韧带、髂胫束）进行系统的粘弹性力学性质的实验研究，通过粘弹性力学模型的建立，推导前交叉韧带及髌韧带、髂胫束的本构方程，对韧带的蠕变和松驰现象进行系统的分析。结果表明，韧带的损伤与韧带的生理力学性质有关，髌韧带的粘弹性性质更接近前交叉韧带，关节内髌韧带转换比髂胫束为佳。     

膝关节前交叉韧带与后交叉韧带粘弹性实验研究

研究了10具新鲜成人尸体膝关节前交叉韧带和后交叉韧带的拉伸力学性质和粘弹性力学性质,对前交叉韧带和后交叉韧带进行单向拉伸实验,得出了破坏载荷,强度极限、最大应变、伸长比、弹性模量.对前交叉韧带和后交叉韧带进行应力松弛,蠕变实验,得出了应力松弛、蠕变实验数据和曲线.对实验数据进行归一化处理,得出了归一化应力松弛函数,蠕变函数,以回归分析的方法处理实验数据,得出了回归系数,很好的拟合了实验曲线.实验结果表明:前交叉韧带的拉伸强度极限、最大应变等大于后交叉韧带,后交叉韧带7200s应力松弛、蠕变量小于前交叉韧带.     

骨科生物降解可吸收内固定物力学特性及固定效应

从理论上讲，生物降解材料是目前最理想的骨科内固定材料。自SchmitfDPolistin刨1969）首先将PGA用于动物的实验性骨折固定材料以来，近30年始终吸引着各国科学家进行了大量的实验研究，并用于临床，但仍存在一些问题。其力学性质及强度衰减就是局限其发展和广泛临床应用的主要原因之一。如何提高材料的力学性质，调控其强度衰减，是各国学者普遍关心的一个重要课题。本文就骨科常用生物降解可吸收材料力学性质的影响因素、变化规律、固定力学效应作一综述，并提出未来研究方向。一、生物降解材料的理论力学研究概况关于骨科常用生物降解…     

人颅骨力学性质的实验研究

本文用颅骨试样进行了准静态下的压缩实验，研究了骨的表观密度、灰度与颅骨力学性质的相关关系，为颅脑损伤分析和模拟试验研究提供了理论依据。     

烤瓷熔附金属修复材料实验力学与计算力学比较研究

研究对烤瓷熔附金属PFM(Porcelain fused to metal)修复材料进行力学分析的实验与计算方法 ,分析其相关程度和内在联系。制作不同金瓷比 ,外形为 2 6mm× 4mm× 1.5mm的PFM试件 15个 ,分 5组 ,每组 3个 ,采用三点弯曲实验测量其弯曲强度及弹性模量 ,观察其变化规律 ,并与理论计算值比较 ,讨论其相关性。发现实验测量结果与理论计算结果有明显相关性 ,可以通过修正的理论公式来预测PFM的力学性质。PFM各组份的几何形态参数和力学参数与其总体力学性质有规律性关系 ,可以用通过校正的理论公式进行预测和改进。     

骨性关节炎对膝关节干骺端松质骨应力松弛性质影响的实验研究

研究正常国人新鲜尸体膝关节干骺端松质骨和老年骨性关节炎病膝关节干骺端松质骨的应力松弛力学性质,为临床提供生物力学参数。取正常和病态膝关节干骺端松质骨,在Shimadzu AUTOGRAPH电子万能试验机上进行应力松弛实验。得出了正常和病态组松质骨7200s应力松弛量、应力松弛随时间的变化规律以及应力松弛方程。表明病态组各项力学性质指标均显著低于正常组。     

Comparison of the structure and mechanical properties of bovine femur bone and antler of the North American elk (Cervus elaphus canadensis)

Antler and limb bone have a similar microstructure and chemical composition. Both are primarily composed of type I collagen and a mineral phase (carbonated apatite), arranged in osteons in compact (cortical bone) sections and a lamellar structure in the cancellous (spongy or trabecular bone) sections. The mineral content is lower in antler bone and it has a core of cancellous bone surrounded by compact bone running through the main beam and tines. The mineral content is higher in the compact compared with the cancellous bone, although there is no difference in ratios of the mineral elements with calcium. Mechanical tests (bend and compression) on longitudinal and transverse orientations of dry and rehydrated compact bone of North American elk (Cervus elaphus canadensis) antlers are compared with known data on other antlers as well as bovine femora. Both dry and rehydrated bones are highly anisotropic, with the bending and compressive strength and elastic modulus higher in the longitudinal than in the transverse direction. There is no significant difference between the bend strength and elastic modulus between dry and rehydrated samples tested in the transverse direction. The elastic modulus measured from the bending tests is compared with composite models. The elastic modulus and bend strengths are lower in the rehydrated condition, but the strain to failure and fracture toughness is much higher compared with dry samples. All antler bone mechanical properties are lower than that of bovine femora. The antler has a much higher fracture toughness compared with bovine femora, which correlates with their main function in intraspecific combat as a high impact resistant, energy absorbent material. A model of compression deformation is proposed, which is based on osteon sliding during shear.     

不同材料赋值属性下髋关节有限元分析

目的 探讨 3 种不同建模方式对髋关节有限元模型生物力学特性的影响,研究出更符合实际的髋关节的材料属性赋值方法。 方法 对髋关节模型进行三维重建,分别采用皮-松质骨赋值法、均一赋值法和灰度赋值法完成材料参数赋值,设定相同的边界条件和载荷,模拟单腿站立位状态下髋关节受力情况,对比 3 组模型的髋关节应力和形变情况。 结果 3 种不同建模方式下髋关节应力均集中于股骨颈内侧,皮-松质骨赋值法、均一赋值法、灰度值赋值法模型 von Mises 应力峰值分别为 11. 04、3. 91、4. 25 MPa。 皮-松质骨赋值法模型最大形变位于股骨大粗隆上部,髋臼与股骨头处最大形变值为 0. 27 mm。 均一赋值法模型及灰度值赋值法模型最大形变位于髋臼与股骨头处,最大形变值分别为 0. 11、0. 12 mm。 结论 根据髋关节 CT 数据灰度值进行梯度赋值,使得髋关节模型材料属性分布更接近骨骼真实的材料属性。     

Assessment of cancellous bone mechanical properties from micro-FE models based on micro-CT, pQCT and MR images.

Recently, new micro-finite element (micro-FE) techniques have been introduced to calculate cancellous bone mechanical properties directly from high-resolution images of its internal architecture. Also recently, new peripheral quantitative computed tomography (pQCT) and magnetic resonance (MR) imaging techniques have been developed that can create images of whole bones in vivo with enough detail to visualize the internal cancellous bone architecture. In this study we aim to investigate if the calculation of cancellous bone mechanical properties from micro-FE models based on such new pQCT and MR images is feasible. Three bone specimens were imaged with the pQCT scanning system and the MR-imaging system. The specimens were scanned a second time using a micro-CT scanner with a much higher resolution. Digitized reconstructions were made based on each set of images and converted to micro-FE models from which the bone elastic properties were calculated. It was found that the results of both the pQCT and the MR-based FE-models compared well to those of the more accurate micro-CT based models in a qualitative sense, but correction factors will be needed to get accurate values.     

股骨头松质骨力学性质实验研究

目的 研究股骨头松质骨力学性质，为临床提供生物力学参数。方法 对正常国人新鲜尸体股骨头松质骨的拉伸、压缩、扭转、剪切、弯曲、冲击力学性能进行实验研究。结果 得出了股骨头松质骨的拉伸、压缩破坏载荷、强度极限、弹性模量，扭转破坏扭矩、扭转剪切强度极限，弯曲破坏载荷、弯曲强度极限、剪切破坏载荷、剪切强度极限，冲击功、冲击韧性等测试指标的实验结果。结论 股骨头松质骨抗压强度大于抗拉强度，压缩弹性模量大于拉伸弹性模量，扭转强度大于剪切强度，抗弯强度与抗压强度接近。     

松质骨弹性模量与表观密度的关系-基于杆-杆结构和带孔板结构相结合的模型

从杆-杆结构模型开始，然后以此框架为基础逐渐填加固体物质形成带孔板的框架模型，从而将松质骨的两种微结构模型结合起来，利用均匀化理论计算松质骨的弹性模量，通过对所得结果的分析，讨论了松质骨的弹性模量与表观密度的关系。得出弹性模量与表观密度的关系为E=1．78p^1.88（GPa），该结果与用胞元结构理论导出的关系式比较接近，可能更合理。     

未成年人胫骨近端松质骨的力学性质及讨论

本文报道了未成年人胫骨近端骺板及松质骨的力学性质。作者指出，未成年人胫骨近端松质骨在构造上呈弹性网状结构，其中充满了红骨髓。对松质骨作单轴压缩试验时有红骨髓溢出，压缩强度极限为０．５４ＭＰａ，远低于成熟骨压缩强度极限。松质骨作为承载结构应是固－液二相耦合承载。     

基于CT图像的长管骨有限元材料属性研究及实验验证

目的探讨经酒精处理的新鲜人体长管骨个性化材料属性定义的方法,以及骨骼材料数目对有限元结果的影响。方法利用断层扫描CT图片,在Mimics中建立股骨干三维实体模型,然后导入Hypermesh中分割成皮质骨、松质骨以及骨髓;根据相关经验公式分别赋于皮质骨和松质骨的材料参数,设置5组材料数目的不同仿真组;在Abaqus中进行线弹性阶段的压缩实验仿真,并进行体外验证实验。结果端部位移在0～1 mm时,松质骨材料数目为1种,皮质骨材料数目大于10种的整体力-位移有限元仿真结果与实测数据平均相对误差在10%左右;骨干的测量点变形量的有限元结果与实测数据相对误差为14.6%。在小位移下0～0.5 mm时1,种皮质骨材料的整体力-位移的仿真结果与实测数据误差为2.83%。结论 (1)利用CT图片灰度值,可以精确定义骨骼各成份的材料属性;(2)皮质骨材料数目设定对有限元仿真结果影响较大,将皮质骨设定10种即可满足有限元分析需要;(3)小变形时,1种材料的皮质骨就能满足分析要求。     

Mechanical characterization of brushite and hydroxyapatite cements

Compression, tension and torsion tests were designed and completed successfully on a brushite and a precipitated hydroxyapatite cement in moist condition. Elastic and strength properties were measured for these three loading cases. For each cement, the full set of strength data was fitted to an isotropic Tsai-Wu criterion and the associated coefficients identified. Since the compressive Young's moduli were about 10% larger than the tensile moduli, the full set of elastic data of each cement was fitted to a conewise linear elastic model. Hysteresis of the stress-strain curves was also observed, indicating dissipation mechanisms within these cement microstructures. A comparison of the measured mechanical properties with human cancellous bone confirmed the indication of brushite as a bone filling material and the potential of the hydroxyapatite cement as a structural biomaterial.     

Rapid and reliable biomechanical screening of injectable bone cements for autonomous augmentation of osteoporotic vertebral bodies: appropriate values of elastic constants for finite element models

We performed finite element analysis studies on 3 three-dimensional representations of a single vertebral body: a regular cube, made of low-density polyurethane foam (foam cube analog); a regular cube considered composed of cancellous bone only (bone cube analog)); and the body of the L2 vertebra (full anatomical body model). Each finite element model was subjected to a compressive load of 2300 N, uniformly distributed over its superior surface. The cancellous and cortical bones were assigned anisotropic elastic properties, while the foam and the endplate material were considered to have isotropic properties. In each representation, the elastic properties of the material(s) were adjusted (from the initial values that were used) to give a stiffness of the representation that was equal to that of the mean result for fresh cadaveric osteoporotic single vertebral bodies, as obtained from ex vivo experimental studies reported in the literature (1226 +/- 996 N mm(-1)). Thus, any one of these representations, when used with the final adjusted value(s) of the elastic constants and modified to include a cylindrical hole filled with a specific volume of bolus of an injected bone cement, may be utilized in the rapid and reliable experimental ex vivo and/or numerical screening of these cements for use in autonomous vertebral body augmentation. This approach has many advantages over those that are currently being used, which are either characterization of the cement in isolation from the vertebral body or use of cadaveric vertebral bodies.     

聚醚醚酮基骨科植入物的改性技术研究

目的 结合聚醚醚酮（PEEK）、聚乳酸（PLA）和硫酸软骨素锶（SrCS）各自的优势，制备出易加工、与松质骨力学性能匹配且兼具生物活性的聚醚醚酮基生物材料。方法 将熔融的PLA充分地填充在PEEK二维编织结构孔隙中，通过热压制备PLA/PEEK复合材料，并对其表面形貌和结构、结晶度、宏观和微观力学强度进行研究。随后在最优力学性能的PLA/PEEK复合材料中引入SrCS并使其与细胞共培养，通过MTT法评价细胞在复合材料上的增殖情况。结果 在155℃和10 MPa的热压条件下，PLA与PEEK细丝结合致密并形成了互锁结构，所得PLA/PEEK复合材料具有与松质骨相似的抗断裂性能、弹性模量和多尺度力学特性。SrCS的引入对复合材料的力学特性进行了微调，并显著提升其生物活性。结论 PLA和SrCS的引入可以有效地改善PEEK基材料的可加工性和生物活性，且结构互锁的PLA/PEEK复合材料具有仿松质骨的力学特性，因此SrCS/PLA/PEEK复合材料有潜力作为新型的骨科修复材料。