Research on Measuring Method of the Bone Stress by X-ray Diffraction properties of HAp Crystals in Living Bone Tissue

皮质骨是由羟基磷灰石(HAP)和胶原蛋白组成的复合材料。由于HAP是一种晶体结构，因此可以用X射线衍射法来测量HAP晶体的应变。然而，骨组织中的HAP晶体结晶度较低。提出了用X射线衍射法从低结晶度HAP晶体的扩散强度分布来测量其晶格应变。此外，为了通过测量HAP晶体的应变来估计骨组织的应变，本工作在宏观尺度上研究了骨组织应变与微观尺度上的HAP晶体晶格应变之间的关系。在拉伸载荷下进行了X射线衍射实验。从牛股骨干皮质区切取大小为40×6×0.8 mm的条状骨标本。通过检测穿过试件的X射线衍射束，在加载…中直接测量晶格应变更多的G方向。用X射线衍射仪测量了HAP晶体中各晶面(002)、(211)和(213)的三个晶格应变。根据无应变状态和应变状态下的X射线衍射图计算了应变。各晶格应变随骨组织应变呈线性增加，且各处均低于骨组织应变。平均晶格应变值随骨组织应变的增加而线性增加。骨轴向标本的平均应变比(平均晶格应变/组织应变)较高。这一趋势与试件弹性模数的差异相吻合。在拉伸载荷作用下，通过X射线衍射法和透射法直接测量出沿加载方向排列的HAP晶体的晶格应变。在相似的宏观应变下，所有试件的晶格应变均低于宏观骨组织应变，而弹性模量值较高的试件的晶格应变高于宏观应变。骨组织应变可以通过计算全剖面的点阵应变和骨组织的弹性模量值来估算。较少

Cortical Bone is a composite material composed of hydroxyapatite (HAp) and collagen. As HAp is a crystalline structure, an X-ray diffraction method is available to measure the strain of HAp crystals. However, HAp crystals in bone tissue have been known to have the low degree of crystallization. X-ray diffraction method was proposed to measure the lattice strain of HAp crystals from the diffusive intensity profile due to low crystallinity. Also, in order to estimate the bone tissue strain with measurements of the strain of HAp crystals, this work investigates the relationship between bone tissue strain on a macroscopic scale and the lattice strain of HAp crystals on a microscopic scale. The X-ray diffraction experiments were performed under tensile loading. Strip bone specimens of 40x6x0.8 mm in size were cut from the cortical region of a shaft of bovine femur. By detecting the diffracted X-ray beam transmitted through the specimen, the lattice strain was directly measured in the loadin … More g direction. Three lattice strains at each lattice planes (002), (211) and (213) in the HAp crystals were measured by the X-ray diffraction system. The strain was calculated from the X-ray diffraction profiles at the non-strained and the strained state. All lattice strain increased linearly with the bone tissue strain and was everywhere lower than the bone tissue strain. The values of mean lattice strain increase linearly with the bone tissue strain. The mean strain ratio (mean lattice strain/ tissue strain) was higher for bone axial specimen. This tendency agreed with the differences in the elastic modulus of specimens. The lattice strain of HAp crystals aligned with a loading direction was obtained directly from diffracted and transmitted X-ray beams measured after penetration of cortical bone specimens under tensile loading. The lattice strain was lower than the macroscopic bone tissue strain in all specimens and higher for specimens with higher elastic modulus under similar macroscopic strains. The bone tissue strain could be estimated from the lattice strain calculated for the whole profile and the elastic modulus of the bone tissue. Less