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，x射线衍射法可以测量HAp晶体的应变。然而，已知骨组织中HAp晶体的结晶程度较低。由于HAp晶体结晶度低，本文提出了x射线衍射法从扩散强度谱测量HAp晶体的晶格应变。此外，为了通过测量HAp晶体的应变来估计骨组织应变，本工作研究了宏观尺度上骨组织应变与微观尺度上HAp晶体晶格应变之间的关系。x射线衍射实验在拉伸载荷下进行。从牛股骨一轴的皮质区切下尺寸为40x6x0.8 mm的条状骨标本。通过检测通过试样的衍射x射线束，直接测量了加载方向上的晶格应变。用x射线衍射系统测量了HAp晶体中每个晶格面（002）、（211）和（213）上的三个晶格应变。根据非应变和应变状态下的x射线衍射曲线计算应变。所有晶格应变均随骨组织应变线性增加，且均低于骨组织应变。平均晶格应变随骨组织应变线性增加。骨轴向试样的平均应变比（平均晶格应变/组织应变）较高。这种趋势与试件弹性模量的差异一致。在拉伸载荷作用下，通过对皮质骨试样进行穿透后的衍射和透射x射线束测量，直接获得了沿加载方向排列的HAp晶体的晶格应变。所有试件的晶格应变均低于宏观骨组织应变，相似宏观应变下弹性模量较高的试件晶格应变高于宏观应变。骨组织应变可以通过计算整个轮廓的晶格应变和骨组织的弹性模量来估计。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