2002 Fiscal Year Final Research Report Summary
Research on X-ray measurements of Remodeling Stress in Living Bone Tissue
| Project/Area Number |
12480254
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biomedical engineering/Biological material science
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| Research Institution | HOKKAIDO UVIERSITY |
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Principal Investigator |
TADANO Shigeru Hokkaido University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (50175444)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Naoki Hokkaido University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (40142202)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Biomechanics / Bone Structure / Remodeling / Cortical Bone / X-ray Diffraction / Residual Stress |
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| Research Abstract |
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
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