骨重建的多尺度力学生物学模型预测骨质疏松和机械废用期间股骨中特定部位的骨丢失
A multiscale mechanobiological model of bone remodelling predicts site-specific bone loss in the femur during osteoporosis and mechanical disuse
摘要：
我们提出了一个多尺度的骨重建力学生物学模型，以研究特定部位的股骨中段骨体积分数的演变。该模型包括激素调节和骨细胞群的生化耦合，对骨转换率的微观结构的影响，和组织的机械适应。微观和组织尺度的应力/应变状态的组织计算从宏观载荷的梁理论和微观力学均匀化的组合。该模型被应用于模拟人类股骨中段扫描的时空演变受到两个放松管制的情况下：（i）骨质疏松症和（ii）机械废用。这两种模拟的失调导致皮质内骨丢失，皮质壁变薄和髓腔扩张，与实验结果一致。我们的模型表明，这些观察结果在很大程度上归因于骨转换率的微观结构的影响。发现机械适应有助于保护骨膜附近的皮质内骨基质。此外，由于由弯矩引入的宏观载荷的不对称性，其导致不均匀的皮质壁厚度。骨内膜附近的机械适应的效果可以很大程度上取决于机械刺激是否包括应力集中效应。
英文摘要：
We propose a multiscale mechanobiological model of bone remodelling to investigate the site-specific evolution of bone volume fraction across the midshaft of a femur. The model includes hormonal regulation and biochemical coupling of bone cell populations, the influence of the microstructure on bone turnover rate, and mechanical adaptation of the tissue. Both microscopic and tissue-scale stress/strain states of the tissue are calculated from macroscopic loads by a combination of beam theory and micromechanical homogenisation. This model is applied to simulate the spatio-temporal evolution of a human midshaft femur scan subjected to two deregulating circumstances: (i) osteoporosis and (ii) mechanical disuse. Both simulated deregulations led to endocortical bone loss, cortical wall thinning and expansion of the medullary cavity, in accordance with experimental findings. Our model suggests that these observations are attributable to a large extent to the influence of the microstructure on bone turnover rate. Mechanical adaptation is found to help preserve intracortical bone matrix near the periosteum. Moreover, it leads to non-uniform cortical wall thickness due to the asymmetry of macroscopic loads introduced by the bending moment. The effect of mechanical adaptation near the endosteum can be greatly affected by whether the mechanical stimulus includes stress concentration effects or not.
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