2014.04.27【英译中】骨的力学性能(45)

金小呆 (かんら) 译坛小生
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发表于:2014-04-27 13:28 [只看楼主] [划词开启]

筒子们…原谅我用英文文献翻译作数……枯燥 乏味……可是我要写论文就得看这个啊…妹啊!英文的啊!!我不是学医的啊!我论文还没写呢啊!!眨眼就五月份了啊!!不谢论文毕不了业啊!!可是我这拖延症是开始不想写现在不会写啊!!!啊!!!!来个人救救我吧!!!我是真的要哭了……要死了……真的真的要死了啊!!!
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3 Mechanical Properties of Bone
I.INTRODUCTION
Before and during the process of testing bone mechanical properties,the researcher has to learn the basic structural and mechanical properties of bone.These properties include cortical and cancellous bone at the level of whole bones,bone tissues,osteons or trabeculae,bone lamellae,and ideally the nano- or ultrastructure such as collagen fibers,fibrils,molecules,and mineral components.These basic structural and mechanical data are searchable in the journal literature and also have been written about in numerous textbooks.
3骨的力学性能
1.前言
在对骨的机械性能进行测试之前,研究人员必须了解骨的基本结构和机械性能。这些属性包括皮质骨和松质骨的整体、骨组织、骨单位、骨小梁片以及理想的纳米或超微米结构,如胶原纤维、纤维、分子和矿物成分。这些基本的结构和数据可以在期刊文献中检索,也可以在许多教科书中查询。
Bone has a hierarchical structure and coherent mechanical properties as proposed initially by Katz in 1970s and further developed recently by Rho et al.and Hoffler et al(see chapter 8).In general,this hierarchical structure and the related mechanical properties can be investigated and considered at the five levels shown in Table 3.1.
骨具有层次结构和连贯的力学性能最初是由 Katz在20世纪所提出的,最近由Rho和Hoffler等人进一步发展。通常来讲,这种分层结构和相关的机械性能是可以进行调查的。


The author believe that one of the reasons to separate whole bone and bone tissue blocks is that the mechanical determinants of these two levels of structures are different.For example,the bending mechanical properties of a long bone are determined by its tubular shape and bone densities,while that of a cortical cut beam are by bone densities and osteonal direction( see section IIB).As pointed out by Katz nearly 20 years ago,it is essential to understand the “from-function”(structure-mechanics)relationship of the bone specimen to be tested.The bone hierarchical composite modeling is based on both the structural evaluations and mechanical measurements at different levels.
笔者认为,可以区别整骨和骨组织块的原因之一是这两个层次的结构力学的决定因素不尽相同。例如,长骨的弯曲力学性能与其管状外形和骨密度有关,而皮质骨却是决定于它的骨密度和骨单位的方向。正如20年前Katz指出的,了解“功能”的本质(结构力学)与进行骨标本的测试是密切相关的。骨的分层复合建模是基于结构的评定和不同层次的力学测量。


However,due to the scope of this text,this chapter covers only the basic mechanical properties of cortical and cancellous bone at whole bone,bone tissue,and microstructural levels(osteon and trabeculae),the effects of porosity and densities on mechanical properties,the anisotropic and heterogeneous characteristics of bone mechanical properties,and some basic considerations of the validity of the continuum assumption commonly used in mechanical testing.
然而,由于篇幅所限,本章只涵盖基本的皮质骨和松质骨在骨,骨组织和微观结构水平(骨小梁)的机械性能、孔隙度和密度对力学性能的影响、骨力学性质的各向异性和特异性,以及一些常用于机械测试连续性检测的初步设想。


For more detailed descriptions of basic and theoretical mechanics of bone,one can refer to several books,including Strength of Biological Materials by Yamada(1970),Mechanical Properties of Bone by Evans(1973),The Mechanical Adaptations of Bones by Currey(1984),Bone Mechanics,edited by Cowin(1999),and Skeletal Tissue Mechanics by Martin et al.and several book chapters or journal articles by Nordin and Frankel (1980),Albright(1987),Einhorn(1996),Hayes and Bouxsein(1997),Whiting and Zernicke(1998),and Rho et al.
 
对于骨的基础和理论力学更详细的说明,可以参考一下几本书:《生物材料的强度》(山田·1970),《骨的力学性质》(Evans·1973),《骨的机械适应性能》(Currey·1984),《骨力学》(Cowin编辑·1999),《骨骼组织力学》(Martin 等)以及弗兰克尔(1980),奥尔布赖特(1987),埃霍恩(1996),海因斯,布克塞因(1997),威丁和Zernicke(1998),和Rho等人发表的期刊文献
II.MECHANICAL PROPERTIES OF CORTICAL BONE
2.皮质骨的力学性能
A.General Mechanical Properties
For mechanical thing,cortical bones are often used as a whole bone or tailored into beams or rods.A whole diaphyseal bone is commonly tested using bending and torsional tests.A beam is a bar or rod with constant cross-sectional shape and area,which can be spherical,square,or rectangular.A variable beam is a beam with inconsistent cross-sectional shape and area,such as long bones.A cantilever beam is a beam that is fixed at one end and usually used for cantilever bending tests.A dumbbell sample is a dumbbell-shaped bone specimen made specifical for mechanical testing,such as tensile or torsional tests.The dense nature of cortical bone determines its strong and stiff mechanical properties compared with cancellous bone.For comparison,Figure3.1gives the elastic modulus and strength of bone(cortical bone)and several other common tissues and biomaterials.
A.一般的机械性能
    带入机械中,皮质骨常常被用作一个整体骨的专用梁或杆。一个完整的骨干常用于弯曲和扭转实验的测试中。一束杆或棒具有固定的横截面形状和面积,可以使球形、方形或者矩形。而可变束的横截面形状和面积并不一致,如长骨。悬臂梁是一端固定的梁,通常用于悬臂梁弯曲实验。哑铃试样可以进行哑铃形骨标本的特定机械测试,如拉伸和扭转。皮质骨的致密性决定了她拥有比松质骨更坚固的机械性能。作为对比,图3.1给出了骨(皮质骨)和其他几种常见的组织和生物材料的弹性模量和强度。


The mechanical properties of cortical bone depend on the type of mechanical testing.According to the data collected in Table 3.2,the strength and elastic modulus by compression tests range from 133 to 295 MPa(20036MPa)and from 14.7 to 34.3 GPa,respectively.The strength and elastic modulus by tensile test range from 92 to 188 MPaand from 7.1 to 28.2 GPa,respectively.The strength and elastic modulus by torsional tests range from 53 to 76 MPaand from 3.1 to 3.7 GPa,respectively.The tensile strength is about 2/3that of compression strength.The torsional(shear)strength is approximately 1/3 to 1/2 of the values of the longitudinal strength(tested by bending,tensile,or compressive tests)(Table 3.3).And the torsional(shear) modulus is only about 1/6 to 1/5 of the longitudinal modulus.Although the tensile test is the standard method for testing mechanical properties of cortical bone,bending tests are used the most often.
皮质骨的机械性能取决于机械测试的类型。根据表3.2中数据可知,在压缩测试中强度和弹性模量分别为133—295MPa和14.7—34.3MPa。拉伸测试中强度和弹性模量范围分别为92—188MPa和7.1—28.2GPa。扭转实验的强度和弹性模量范围分别为53—76MPa和3.1—3.7GPa。抗拉强度为抗压强度的2/3,扭转(剪切)强度约为纵向强度值(弯曲、拉伸和抗压测试)的1/3到1/2。虽然拉伸试验是检验皮质骨力学性能的标准方法,但是弯曲试验是最常用的。


The bending strength and elastic modulus of cortical bone range from 35 to 283 MPa and from 5 to 23 GPa,respectively(excluding the questionable values marked with,Tables 3.3 and 3.4). Note the significant differences between the two levels.
皮质骨的抗弯强度和弹性模量范围为35—283MPa和5—23GPa(表3.3、3.4)要注意这两个水平之间的显著差异。


As mentioned earlier,the bending mechanical properties of a long bone are determined by its tubular shape and bone densities,while that of cortical cut beams are by bone densities and osteonal direction.Table3.5 contains the average values of the individual reports listed in Tables 3.3 and 3.4.It clearly shows that the values of strength and elastic modulus of the two levels of bone tissue are different.Both the strength and elastic modulus of whole bone are about 60% of that of cortical bone beams.One should be aware of the fact that besides the true difference between the two levels of structures,there are several other factors possibly playing important roles,such as the equations used for calculations,the specimen aspect ratio (larger for beams ), or the size of the specimens tested.These speculations have already been partially addressed by Sedlin and Hirsch.Further studies are still needed to determine the relevance of each of these factors.
 
如前所述,长骨的弯曲力学性能与其管状外形和骨密度有关,而皮质骨却是决定于它的骨密度和骨单位的方向。表3.5和表3.4中的平均值清除表明,强度和骨组织的两个层次弹性模量不同。整个骨的强度和弹性模量约为皮质骨的60%,人们应该意识到,除了结构和两个层面之间的差别,还有其他几个因素可能发挥了重要作用,如用于计算的方程,试样的纵横比(较大的梁),或测试试样的大小。相关设想由美国的Sedlin和Hirsch提出,而这些因素的相关性仍在进一步研究中。
B.Bone Density
The material density of cortical bone is the wet weight divided by the specimen volume.It is a function of both porosity and mineralization of the bone materials.Cortical bone has an average apparent density of approximately 1.9 g/cm的立方。For cortical bone,apparent density and material density are basically the same,as there is no marrow space in compact bone.Therefore,”cortical bone density “is commonly used to describe the density of cortical bone.There is a positive correlation between apparent density of cortical bone and its mechanical properties.The true meaning of bone mineral density (BMD) is bone mineral mass er unit bone volume,or “ash density” if an ashing (or burning ) method is used.Similarly,the true meaning of bone mineral content(BMC)describes the ratio of unit weight of the mineral portion to dry bone unit weight and is frequently reported as a percentage.
B.骨密度
皮质骨的材料密度是湿重除以试样体积。由孔隙率和骨矿化组成的函数。皮质骨有较为平均的表面密度1.9 g/cm3.皮质骨的表面密度和材料密度基本相同,其内部基本没有骨髓的空间。因此,“骨密度”通常描述的是皮质骨密度。皮质骨的表观密度和力学性能之间存在正相关关系。骨密度(BMD)的真正含义是骨质量单元骨体积,或“灰密度”,如果一个灰化(或燃烧)可以作为一个可应用的方法。同样,骨矿含量(BMC)描述的真正含义是矿产部的单位重量比干骨单位重量的百分比,也很常见。


BMD and BMC are positively correlated with the strength and stiffness of various bones, such as human ulna,human femur and tibia,bovine femur and tibia,feline femur ,and a wide variety of animal bones.Using tension testing of wet bovine Haversina cortical bone,Burstein et al.demonstrated the role of mineral content on mechanical strength.Progressive surface decalcification of this bone with dilute hydrochloric acid resulted in progressive decreases in the tension yield point and the ultimate stress with no change in the yield strain or ultimate strain unless decalcification was complete.Their finding are consistent with an elastic-plastic model for the mineral phase of bone tissue in which the mineral contributes the major portion of the amount or mineral density of cortical bone exert a more pronounced influence on its elastic property than would similar changes in trabecular bone.Currey studied the relationship between the bending and tensile elastic modulus of cortical bone from 17 vertebrate species to porosity and mineralization.He found that these two factors together accounted for 84% of the stiffness variation.Recently,the influence of wet and dry apparent density,percentage of mineral on the tension and shear fracture toughness of tubular bone have been studied by Yeni rt al.They found that compositional parameters altogether can explain 35 to 59% of the variation in fracture toughness of the cortical bone.
BMD和BMC与强度和各种骨刚度呈正相关,如人尺骨,人体股骨和胫骨,股骨和胫骨的股骨,牛,猫,和各种各样的动物骨头。通过骨皮质张力测试,伯斯坦等人证明了矿物含量对机械强度的作用。这种渐进表面脱钙骨与稀盐酸导致,在拉伸屈服点逐步降低与屈服应变和极限应变极限应力不改变,除非脱钙是完整的。他们利用弹塑型模型进行的研究中有相同发现:矿物质密度对于皮质骨弹性模量的影响比相同条件下的骨小梁要显著。Currey对17种动物脊椎进行了孔隙度、矿化的研究,从而确定了皮质骨弯曲模量和拉伸弹性模量之间的关系。他发现,这两个因素加在一起占刚度变化的84%。今日,在干湿度对表面密度的影响、矿物对管状骨的拉伸和剪切韧性百分比的影响等研究中,Yeni等人发现,组成参数完全可以解释35%—59%的皮质骨断裂韧性的变化。




Many reports have shown linear or exponential increases in bone stiffness with increasing mineralization,such as the one proposed by Schaffler and Burr.
许多报告都表明了骨矿化度的线性或指数增加,如Schaffler and Burr.的方案。
With the development of modern absorptiometric techniques,BMD and BMC can be measured noninvasively.Such methods include radiographic absorptiomentry (RA),single photon absorptiometry(SPA),dual energy absorptiometry(DEA),or dual-energy X-ray absorptiometry(DEXA),quantitative computed tomography(QCT),micro-CT(µCT),peripheral CT(pCT),magnetic resonance imaging(MRI),and ultrasound methods.Extensive studies have been done on the correlation between cortical bone densities measured by above-mentioned methods,such as BMD and BMC,and the mechanical properties of bone.These methods are commonly used for predicting fracture risk and for the diagnosis of osteoporsis.
随着现代吸收测量技术的发展,BMD和BMC可以采用非侵入性测量方法。这些方法包括射线(RA),单光子吸收法(SPA),双能量骨密度仪(DEA),或双能X线骨密度仪(DEXA),定量计算机断层扫描法(QCT),微CT(µCT),外周CT(PCT),磁共振成像(MRI),超声方法等。用上述方法测量骨密度的相关性,如BMD和BMC,和骨的力学性能。这些方法通常用于预测骨折风险和骨质疏松症的诊断。




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