Berli Marcelo, Borau Carlos, Decco Oscar, Adams George, Cook Richard B, García Aznar José Manuel, Zioupos Peter
Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Ruta 11, Oro Verde, Entre Ríos, República Argentina.
Departamento de Ingeniería Mecánica, Instituto de Investigación en Ingeniería de Aragón (I3A), Universidad de Zaragoza, Zaragoza, España.
PLoS One. 2017 Mar 17;12(3):e0173228. doi: 10.1371/journal.pone.0173228. eCollection 2017.
Bone is a living tissue whose main mechanical function is to provide stiffness, strength and protection to the body. Both stiffness and strength depend on the mineralization of the organic matrix, which is constantly being remodelled by the coordinated action of the bone multicellular units (BMUs). Due to the dynamics of both remodelling and mineralization, each sample of bone is composed of structural units (osteons in cortical and packets in cancellous bone) created at different times, therefore presenting different levels of mineral content. In this work, a computational model is used to understand the feedback between the remodelling and the mineralization processes under different load conditions and bone porosities. This model considers that osteoclasts primarily resorb those parts of bone closer to the surface, which are younger and less mineralized than older inner ones. Under equilibrium loads, results show that bone volumes with both the highest and the lowest levels of porosity (cancellous and cortical respectively) tend to develop higher levels of mineral content compared to volumes with intermediate porosity, thus presenting higher material densities. In good agreement with recent experimental measurements, a boomerang-like pattern emerges when plotting apparent density at the tissue level versus material density at the bone material level. Overload and disuse states are studied too, resulting in a translation of the apparent-material density curve. Numerical results are discussed pointing to potential clinical applications.
骨骼是一种活组织，其主要机械功能是为身体提供刚度、强度和保护。刚度和强度都取决于有机基质的矿化，而有机基质通过骨多细胞单元（BMU）的协同作用不断重塑。由于重塑和矿化的动态过程，每块骨骼样本都由在不同时间形成的结构单元（皮质骨中的骨单位和松质骨中的骨小梁）组成，因此呈现出不同水平的矿物质含量。在这项工作中，使用一个计算模型来理解不同载荷条件和骨孔隙率下重塑和矿化过程之间的反馈。该模型认为破骨细胞主要吸收骨骼中更靠近表面的部分，这些部分比内部较老的部分更年轻且矿化程度更低。在平衡载荷下，结果表明，与具有中等孔隙率的骨体积相比，孔隙率最高和最低的骨体积（分别为松质骨和皮质骨）往往会形成更高水平的矿物质含量，从而呈现出更高的材料密度。与最近的实验测量结果高度一致，当绘制组织水平的表观密度与骨材料水平的材料密度关系图时，会出现类似回旋镖的模式。还研究了过载和废用状态，结果导致表观材料密度曲线发生平移。对数值结果进行了讨论，并指出了潜在的临床应用。
