Fazzalari N L, Forwood M R, Manthey B A, Smith K, Kolesik P
Division of Tissue Pathology, Institute of Medical and Veterinary Science, Adelaide, SA, Australia.
Bone. 1998 Oct;23(4):373-8. doi: 10.1016/s8756-3282(98)00111-2.
The accumulation of microdamage in bone may contribute to loss of bone quality in osteoporosis, and the role of microdamage in the etiology of fatigue fractures is unknown. Microdamage created during testing, ex vivo, can increase the fragility of bone by decreasing the load necessary to cause fracture. Microdamage can also accumulate in vivo, but its influence on bone fragility is unknown. To date, stained microcracks are the only criteria to have been correlated with bone mechanics, leaving the influence of ultrastructural damage on bone fragility open for scrutiny. Staining en bloc has identified three morphological features in the tissue, discrete microcracks, cross-hatch staining, and diffuse staining. The relationship between these features and their identification as microdamage remains equivocal. The purpose of this study was to investigate the three-dimensional nature of microdamage in cancellous bone and also to describe stained microcracks, cross-hatch staining, and diffuse staining and to determine whether they all relate to microdamage in bone. Laser scanning confocal microscopy that provides improved spatial resolution over bright-field microscopy was used to visualize bone damage. It was found that crack surface density was highly correlated with crack density (r = 0.95, p < 0.0001), suggesting that the crack surface of preexisting cracks increases as new cracks are formed or submicroscopic cracks become visible under bright-field microscopy. Cross-hatch staining and diffuse staining included ultra-microcracks about 10 microm in length. The ultra-microcracks in cross-hatch staining were organized in bands and surrounded by diffuse staining. This study demonstrates that damage in bone occurs over a wide range and that discrete microcracks, cross-hatch staining, and diffuse staining are all indicative of bone damage. The diffuse staining still evident in association with the ultra-microcracks seen in cross-hatch staining and diffuse staining is probably due to damage at a still smaller scale than we have been able to investigate.
骨骼中微损伤的积累可能导致骨质疏松症患者骨质流失，而微损伤在疲劳性骨折病因中的作用尚不清楚。体外测试过程中产生的微损伤会通过降低引发骨折所需的负荷来增加骨骼的脆性。微损伤也会在体内积累，但其对骨骼脆性的影响尚不清楚。迄今为止，染色微裂纹是唯一与骨力学相关的标准，超微结构损伤对骨骼脆性的影响仍有待研究。整体染色已在组织中识别出三种形态特征：离散微裂纹、交叉阴影染色和弥漫性染色。这些特征与微损伤的识别之间的关系仍不明确。本研究的目的是研究松质骨中微损伤的三维性质，并描述染色微裂纹、交叉阴影染色和弥漫性染色，以确定它们是否都与骨骼中的微损伤有关。与明场显微镜相比，激光扫描共聚焦显微镜具有更高的空间分辨率，用于可视化骨损伤。研究发现，裂纹表面密度与裂纹密度高度相关（r = 0.95，p < 0.0001），这表明随着新裂纹形成或亚微观裂纹在明场显微镜下可见，原有裂纹的裂纹表面会增加。交叉阴影染色和弥漫性染色包括长度约为10微米的超微裂纹。交叉阴影染色中的超微裂纹呈带状排列，并被弥漫性染色包围。本研究表明，骨骼损伤范围广泛，离散微裂纹、交叉阴影染色和弥漫性染色均表明存在骨损伤。与交叉阴影染色和弥漫性染色中所见超微裂纹相关的弥漫性染色仍然明显，这可能是由于损伤的尺度比我们能够研究的还要小。
