Abstract：
Existing in silico models for lamellar bone adaptation to mechanical loading are unsuitable for predicting woven bone growth. This anomaly is due to the difference in mechanobiology of the woven bone with respect to that of the lamellar bone. The present study is aimed at developing an in silico bone-adaptation model for woven bone at cellular and tissue levels. The diffusion of Ca2+ ions reaching lining cells from the osteocytic network and the bone cortex in response to a mechanical loading on the cortical bone has been considered as a stimulus. The diffusion of ions within osteocytic network has been computed with a lacunar-canalicular network (LCN) in which bone cells are uniformly arranged. Strain energy density is assumed to regulate ion flow within the network when the induced normal strain is above a threshold level. If the induced strain exceeds another higher threshold level, then the strain with a power constant is additionally assumed to regulate the stimulus. The intracellular flow of Ca2+ ions within the LCN has been simulated using Fick\'s laws of diffusion, using a finite element method. The ion diffusion from bone cortex to vesicles has been formulated as a normal strain with a power constant. The stimuli reaching the surface cells are assumed to form the new bone. The mathematical model closely predicts woven bone growth in mouse and rat tibia for various in vivo loading conditions. This model is the first to predict woven bone growth at tissue and cellular levels in response to heavy mechanical loading.
摘要：
现有的板层骨适应机械载荷的计算机模拟模型不适合预测机织骨生长。这种异常是由于编织骨相对于板层骨的机械生物学不同。本研究旨在开发一种用于细胞和组织水平的编织骨的计算机骨适应模型。响应于皮质骨的机械载荷，Ca2离子从骨细胞网络和骨皮质扩散到衬里细胞被认为是一种刺激。已通过腔隙-小管网络（LCN）计算了骨细胞网络中离子的扩散，其中骨细胞均匀排列。假设应变能量密度在诱导的法向应变高于阈值水平时调节网络内的离子流。如果诱导应变超过另一个较高的阈值水平，然后额外假设具有功率常数的应变来调节刺激。使用Fick扩散定律模拟了LCN中Ca2离子的细胞内流动，使用有限元方法。从骨皮质到囊泡的离子扩散已被配制为具有功率常数的正常应变。假定到达表面细胞的刺激形成新骨。在各种体内负荷条件下，该数学模型可紧密预测小鼠和大鼠胫骨中的编织骨生长。该模型是第一个预测组织和细胞水平的编织骨生长以响应重型机械负荷的模型。
