Li Taiyang, Chen Zebin, Gao Yan, Zhu Lingsu, Yang Ruili, Leng Huijie, Huo Bo
Department of Mechanics, School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, PR China.
Laboratory of Biomimetic Nanomaterials, Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, PR China.
J Biomech. 2020 Aug 26;109:109912. doi: 10.1016/j.jbiomech.2020.109912. Epub 2020 Jul 2.
The structure of a bone tissue is capable of adapting to mechanical loading through the process of bone remodeling, which is regulated by osteoblasts and osteoclasts. Fluid flow within trabecular porosity under cyclic loading is one of the factors stimulating the biological response of osteoblasts and osteoclasts. However, the relation between loading directions and interstitial fluid flow was seldom studied. In the present study, a finite element model based on micro-computed tomographic reconstructions is built by using a mouse femur. Results from the fluid-solid coupling numerical simulation indicate that the loading in different directions generates a distinct distribution of von Mises stress in the bone matrix and a fluid shear stress (FSS) in the bone marrow. The loading along the physiological direction leads to a more uniform distribution of solid stress and produces an FSS level beneficial to the biological response of osteoblasts and osteoclasts compared with those along the non-physiological direction. There was a minimum threshold line of wall FSS with a specific solid stress at the bone surface, suggesting that the wall FSS is mainly induced by the solid strain. These results may offer fundamental data in understanding the mechanical environment around osteoblasts and osteoclasts and the cellular and molecular mechanisms of mechanical loading-induced bone remodeling.
骨组织的结构能够通过骨重塑过程适应机械负荷，该过程由成骨细胞和破骨细胞调节。循环负荷下小梁孔隙内的流体流动是刺激成骨细胞和破骨细胞生物学反应的因素之一。然而，负荷方向与间质液流动之间的关系鲜有研究。在本研究中，使用小鼠股骨建立了基于微观计算机断层扫描重建的有限元模型。流固耦合数值模拟结果表明，不同方向的负荷在骨基质中产生不同的冯·米塞斯应力分布，并在骨髓中产生流体剪应力（FSS）。与非生理方向的负荷相比，沿生理方向的负荷导致固体应力分布更均匀，并产生有利于成骨细胞和破骨细胞生物学反应的FSS水平。在骨表面存在具有特定固体应力的壁FSS最小阈值线，表明壁FSS主要由固体应变诱导。这些结果可能为理解成骨细胞和破骨细胞周围的力学环境以及机械负荷诱导骨重塑的细胞和分子机制提供基础数据。
