School of Mathematical Sciences, Monash University, VIC 3800, Australia; Engineering Computational Biology Group, The University of Western Australia, WA 6009, Australia.
Int J Numer Method Biomed Eng. 2013 Dec;29(12):1307-22. doi: 10.1002/cnm.2567. Epub 2013 Jul 1.
Age-related bone loss and postmenopausal osteoporosis are due to a dysregulation of bone remodelling in which less bone is reformed than resorbed. This dysregulation of bone remodelling does not occur with equal strength in all bone regions. Loss of bone is more pronounced near the endocortical surface. This leads to thinning of the cortical wall proceeding from the endosteum, a process sometimes called 'trabecularisation'. In this paper, we investigate the influence of the nonuniform distribution of bone surface within bone tissue for osteoporotic bone losses. We use a spatio-temporal computational model of bone remodelling in which microstructural changes of bone tissue are represented by a phenomenological relationship between bone specific surface and bone porosity. The simulation of an osteoporotic condition by our model shows that the evolution of bone porosity within a bone cross section is significantly influenced by the nonuniform availability of bone surface. Greater bone loss occurs near the endocortical wall, leading to cortical wall thinning and to an expansion of the medullary cavity similar to cross-sectional observations from human femur midshafts. Our model suggests that the rate of cortical wall thinning is fast/slow in the presence/absence of an adjacent trabecular or trabecularised bone compartment.
与年龄相关的骨丢失和绝经后骨质疏松症是由于骨重建的失调引起的，在这种失调中，形成的骨比吸收的骨少。这种骨重建的失调在所有骨区域并不以相同的强度发生。骨丢失在靠近内皮质表面更为明显。这导致皮质壁从骨内膜开始变薄，这个过程有时被称为“骨小梁化”。在本文中，我们研究了骨组织内骨表面的不均匀分布对骨质疏松性骨丢失的影响。我们使用骨重建的时空计算模型，其中骨组织的微观结构变化由骨比表面积和骨孔隙率之间的现象关系来表示。我们的模型模拟骨质疏松症的情况表明，骨横截面上的骨孔隙率的演化受到骨表面不均匀分布的显著影响。靠近内皮质壁的骨丢失更大，导致皮质壁变薄，骨髓腔扩张，类似于人类股骨中段的横截面上的观察结果。我们的模型表明，在存在/不存在相邻的小梁或小梁化骨区室的情况下，皮质壁变薄的速度较快/较慢。
