O'Brien F J, Taylor D, Dickson G R, Lee T C
Department of Anatomy, Royal College of Surgeons in Ireland.
J Anat. 2000 Oct;197 Pt 3(Pt 3):413-20. doi: 10.1046/j.1469-7580.2000.19730413.x.
Microdamage in bone contributes to the loss of bone quality in osteoporosis and is thought to play a major role in both fragility and stress fractures (Schaffler et al. 1995). In this study, in vivo microcracks in human ribs were bulk-stained in basic fuchsin and viewed in longitudinal section and in 3 dimensions using 2 different computer-based methods of reconstruction: (1) serial sectioning of methylmethacrylate embedded sections using a sledge macrotome and identification of microcracks using UV epifluorescence followed by computerised reconstruction of microcracks using software and (2) laser scanning confocal microscopy of thick sections followed by reconstruction of microcracks into a 3-D image. The size and shape of microcracks were found to be similar using both techniques. Both techniques of reconstruction showed microcracks to be approximately elliptical in shape. From the serial sectioning reconstructions (n = 9), microcracks were found to have a mean length of 404 +/- 145 microm (mean +/- S.D.) (in the longitudinal direction) and mean width of 97 +/- 38 microm (in the transverse direction). Using epifluorescence microscopy, 92 microcracks were identified; mean microcrack length was 349 +/- 100 microm in the longitudinal direction. This was consistent with other results (Burr & Martin, 1993) and with the theoretical prediction of an elliptical crack shape with aspect ratio (longitudinal: transverse) of 5:1 deduced from analysis of random 2-D sections (Taylor & Lee, 1998). The results obtained provide new data on the nature of microcracks in bone and the method has the potential to become a useful tool in the calculation of stress intensity values which indicate the probability of an individual microcrack propagating to cause a stress or fragility fracture.
骨骼中的微损伤会导致骨质疏松症患者骨质流失，并且被认为在脆性骨折和应力性骨折中都起主要作用（沙夫勒等人，1995年）。在本研究中，对人肋骨的体内微裂纹用碱性品红进行整体染色，并在纵切面中观察，且使用两种不同的基于计算机的重建方法在三维空间中观察：（1）使用大切片机对甲基丙烯酸甲酯包埋切片进行连续切片，并用紫外落射荧光识别微裂纹，随后使用软件对微裂纹进行计算机重建；（2）对厚切片进行激光扫描共聚焦显微镜观察，随后将微裂纹重建为三维图像。结果发现，两种技术所观察到的微裂纹的大小和形状相似。两种重建技术均显示微裂纹大致呈椭圆形。从连续切片重建结果（n = 9）来看，微裂纹在纵向的平均长度为404 +/- 145微米（平均值 +/- 标准差），横向平均宽度为97 +/- 38微米。使用落射荧光显微镜，共识别出92条微裂纹；微裂纹在纵向的平均长度为349 +/- 100微米。这与其他结果（伯尔和马丁，1993年）一致，也与从随机二维切片分析推导得出的椭圆形裂纹形状的理论预测一致，该椭圆形裂纹的纵横比（纵向：横向）为5:1（泰勒和李，1998年）。所获得的结果为骨骼中微裂纹的性质提供了新数据，并且该方法有可能成为计算应力强度值的有用工具，应力强度值可表明单个微裂纹扩展导致应力性骨折或脆性骨折的可能性。
