多载荷下带有生理限定应力的松质骨细观结构模拟

SIMULATIONS OF MICROSTRUCTURE OF CANCELLOUS BONE WITH PHYSIOLOGICALLY LIMITED STRESSES UNDER DIFFERENT LOADS

松质骨是骨的重要组成部分 ,属多胞体结构 ,由于构成松质骨的小梁骨尺寸较小、形状多变 ,因此给松质骨的研究增加了困难。本文把负反馈调节的生理特征引入骨再造模拟中 ,提出带有生理限定应力的骨再造自适应模型。模型具有骨再造局部适应的正反馈调节与整体控制的负反馈调节的生理调整过程 ,使骨结构内的应力控制在生理限定应力以下 ,维持骨力学环境的稳定。使用此模型在几种不同的力学环境下模拟了松质骨结构 ,定量地预测了松质骨细观结构与其力学环境的对应关系 ,同时表明了松质骨细观结构与力学环境的适应性。模拟结果与真实松质骨细观结构的典型部分相一致。

Cancellous bony tissue is an important part of bone, which is porous, made of an interconnecting framework of trabeculae. The cancellous bony structure, however, adapts to the variation of the mechanical environment to which it is exposed. The researching of cancellous bone is very difficult due to the smaller dimension and multiple shapes of trabeculae. In this paper, a self-adaptive, physiologically controlled model of bone remodeling with limited stress is suggested. We propose that there is a physiologically limited stress during steady physiological bony processes. The new concept is introduced in equations of bone remodeling, which produces the coupling physiological processes of bone remodeling through local adaptation under global adjustment. The model makes the bony structural stress to be controlled not to surpass the physiologically limited stress, which embodies internal mechanical environment stability in bony tissue, namely homeostasis. The model also reflects the two adjusting modes of positive or negative feedback during bony physiological processes. Current equations for bone remodeling were used to predict bony structure only by local adaptation of positive feedback regulation. The microstruc of cancellous bone can be divided into three types ture, namely models of plate-rod, rod-rod and plate-plate structures. These microstructures of cancellous bone adapting to mechanical environment can be quantitatively analyzed. The results are in good accordance with typical density distribution in real cancellous bone.