Study on mechanism of trabecular pattern using microcomputed tomography --development of new theoretical model--

点击翻译按钮获取中文摘要

Fractal is a mathematical theory developed by Mandelbrot and fractal dimension can be used as an index of complexity of a certain pattern. First, we made it clear that there are significant characteristics of fractal in trabecular bone architecture. Furthermore, in development of microCT, we established the method of fractal dimension as new parameter of complexity of trabecular microarchitecture.Secondly, we investigated the effects of menatetrenone (2-methyl-3-all-trans-tetraprenyl-1, 4-naphthoquinone), a vitamin K2 on 3-D trabecular microarchitecture using an animal model for postmenopausal osteoporosis induced by ovariectomy and a calcium-deficient diet. This study suggests that an 8-week administration of menatetrenone protects against the loss of trabecular bone volume and its connectivity in the osteoporotic rat model, when the treatment is started just after the ovariectomy.Thirdly, in order to investigate morphological changes of the 5th caudal bone in rats' under mechanical loading, the non-invasive and periodic measurements were carried out by using micro CT.The cross-sectional area of the axial or offset loading rat increased up to 25 percent while the increasing rate in the control rat was about 5 percent. The finite element method under the offset loading condition showed more symmetric stress distribution in the offset loading rat than in the axial loading rat and control rat. These results indicated that C5 were adapted to the offset load by remodelling bone architecture.Finally, the study was performed to investigate the effects of externally applied pulsing electromagnetic fields (PEMF) on trabecular conformation in osteoporotic rats. The 3D-reconstructed images and the bone volume density indicated that the externally applied PEMF prevented bone loss at the center of trabeculae in the distal portion of the femur.