The effect of bone microstructure on the initiation and growth of microcracks
The effect of bone microstructure on the initiation and growth of microcracks
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DOI：
10.1016/j.orthres.2004.08.005
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发表时间：
2005-03-01
影响因子：
2.8
通讯作者：
Lee, TC
中科院分区：
文献类型：
--
作者：
O'Brien, FJ;Taylor, D;Lee, TC
骨质骨通常被比作复合材料和金属，因为材料内部的不连续可能为裂纹的萌生提供应力集中的位置，并成为裂纹扩展的障碍。然而，几乎没有实验数据来支持这些假设。在80 Mpa的应力范围内，以特定的间隔对骨试件进行循环压缩疲劳试验。对不合格的标本进行切片，并使用紫外荧光显微镜标记微裂纹。测量微裂纹长度，并记录其与次生骨周围骨水泥线的关系。还测量了遇到水泥线时的微裂纹长度。当遇到水泥线时，不到100亩的微裂缝停止生长。在遇到骨周围的水泥线后，长度超过100微米的微裂纹继续生长。只有长度大于300微米的微裂纹才能穿透骨质，这些微裂纹是唯一观察到的导致试件失效的微裂纹。这些实验数据支持这样一种假说，即次级骨粒是密质骨中裂纹扩展的障碍。然而，它表明，这种微观结构障碍效应依赖于遇到骨子时的裂纹长度。对于绝大多数的裂缝来说，骨素起到了阻碍生长的作用，但对于少数足够长并确实突破了水泥线的裂缝来说，骨素实际上可能是骨骼中的弱点，促进了裂缝的扩展。(C)2004年骨科研究会。爱思唯尔有限公司出版。保留所有权利。
Osteonal bone is often compared to a composite material and to metals as discontinuities within the material may provide sites of stress concentration for crack initiation and serve as barriers to crack growth. However, little experimental data exist to back up these hypotheses. Fluorescent chelating agents were applied at specific intervals to bone specimens fatigue tested in cyclic compression at a stress range of 80 MPa. The failed specimens were sectioned and labelled microcracks identified using UV epifluorescence microscopy. Microcrack lengths were measured and their relationship to cement lines Surrounding secondary osteons recorded. Microcrack length at the time of encountering a cement line was also measured. Microcracks of less than 100 mu m stopped growing when they encountered a cement line. Microcracks of greater than 100 mu m in length continued to grow after encountering a cement line surrounding an osteon. Only microcracks greater than 300 mu m in length were capable of penetrating osteons and these microcracks were the only ones which were observed to cause failure in the specimen. These experimental data support the hypothesis that secondary osteons act as barriers to crack propagation in compact bone. However, it shows that this microstructural barrier effect is dependent on the crack length at the time of encountering an osteon. For the vast majority of cracks, osteons act as barriers to growth but for the minority of cracks that are long enough and do break through the cement line, an osteon may actually act as a weakness in the bone and facilitate crack propagation. (c) 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.