Research on X-ray measurements of Remodeling Stress in Living Bone Tissue

骨组织是由羟基磷灰石（Hap）和胶原蛋白组成的复合材料。由于骨组织中的羟基磷灰石形成晶体结构，x射线衍射法可用于测量羟基磷灰石的应变。本研究提出了一种测量兔胫骨骨组织残余应力/应变的x射线衍射方法。在非应力状态下，以直径小于40微米的骨粉作为对照试样。从测量结果可以清楚地看出，骨组织中存在残余应力的分布。兔胫骨近内侧区域存在骨轴向残余拉伸应力。压应力发生在其他区域。此外，通过对胫骨标本从骨结构尺度到骨组织尺度的顺序切割，研究了残余应力产生的机理。骨重塑是骨组织和结构对机械环境的功能适应现象。残余应力…更多的ss将成为诱发重塑的机械触发因素。在使用具有独特波长的特征x射线的x射线衍射方法中，致密骨中的Hap比钢等金属具有更低的结晶性。衍射光强的峰值位置不容易从渐变光强角曲线中确定。本文提出了一种从整个衍射剖面信息计算晶格应变的方法。本实验从牛股骨一轴的皮质骨上切下28x8x2 mm大小的条状标本，其长轴与骨轴或周向对齐。为了确定骨组织中施加的宏观应变与晶格应变之间的关系，研制了一种四点弯曲装置，在x射线照射过程中对试样施加弯曲载荷。在x射线照射下，将应变片粘接在试样表面的另一侧，测量试样的宏观应变。结果表明，该方法的测量精度得到了较好的提高。少

Bone tissue is a composite material composed of hydroxyapatite (Hap) and collagen. Because Hap in bone tissue makes a crystal structure, an X-ray diffraction method is available to measure the strain of Hap. This study presents an X-ray diffraction method of measuring the residual stress/strain in bone tissue of rabbit's tibia . Bone powder of the diameter less than 40 micrometer was used as a control specimen at non-stressed state. From the measurements, it was clear that the distribution of residual stress existed in the bone tissue. The tensile residual stress at bone axial direction occurred in the proximal-medial region of rabbit's tibia. The compressive stress occurred in the other regions. In addition, the mechanism to generate the residual stress was investigated by sequential cutting of the tibia specimen from bone structure scale to bone tissue scale. The remodeling is a phenomenon that bone tissue and structure adapts functionally to mechanical environment. The residual stre … More ss will become a mechanical trigger to induce the remodeling.In the X-ray diffraction method using characteristic X-rays with a unique wavelength, Hap in compact bone has much lower crystallization than metal as steel. The peak position of diffracted intensity is not easy to determine form the gradual intensity-angle profile. This work proposes a method to calculate the lattice strain from the information of a whole diffraction profile without a peak position. In this experiment, strip specimens of 28x8x2 mm in size with their long axis aligned to the bone axial or the circumferential direction were cut from cortical bone in a shaft of bovine femur. To confirm the relationship between applied macroscopic strain and lattice strain in bone tissue, a four-point bending device was developed to apply bending load to the specimen during the X-ray irradiation. Macroscopic strain of the specimen was measured by a strain-gauge bonded to opposite side of the surface irradiated by X-rays. As a result, the accuracy of measurement by this method was better improved. Less