![]() ![]() The origin of damage at the ultrastructural level is not known. 2000) and adaptation ( Prendergast & Taylor, 1994 Lee et al. 1985 Martin, 1992 Mori & Burr, 1993 Bentolila et al. Such cracks have been implicated in physiological phenomena, including stress fractures ( Burr et al. Although a precise definition of bone quality is difficult to obtain, it includes parameters such as morphology of bone, rate of bone turnover, the degree of mineralization of bone matrix and the amount of microdamage present in the bone tissue ( Bouxsein, 2003).įatigue damage in bone manifests itself in the form of microcracks. There is a growing awareness that a reduction in bone mineral density is not the sole pathology underlying osteoporosis the missing factor appears to be bone quality. Bones become fragile and prone to fracture. ![]() Osteoporosis is a disease characterized by loss of bone mass and changes in tissue microarchitecture of the bone, which compromise bone quality. The mean (± SD) length and width of labelled microcracks were 488 ± 151 and 88 ± 21 µm, respectively. Cracks were elliptical in shape, longer in the longitudinal direction and with a mean aspect ratio of 5.5 ± 1.05. ![]() A three-dimensional image of each microcrack was reconstructed using computer software, and its dimensions measured. A two-dimensional image of each section was examined using an epifluorescence microscope and images transferred to a PC via a CCD low-light colour video camera. A series of thin longitudinal sections were cut using a sledge macrotome. Holes were drilled into bone samples and used as reference points for reconstructions. Samples were tested at a frequency of 30 Hz under load control at a stress range of 100 MPa. ![]() Beam-shaped bone samples from sheep radii were prepared and stained with fluorochrome dyes and tested in cyclical fatigue under four-point bending in a servo-hydraulic fatigue-testing machine. In order to detect and monitor their growth, and to use these data to predict fractures, it is essential to obtain quantitative data regarding their shape in three dimensions. Microcracks have been implicated in the loss of bone quality for osteoporosis. ![]()
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