Weinans H
Erasmus Orthopaedic Research Lab., Erasmus University Rotterdam, The Netherlands.
Technol Health Care. 1998 Dec;6(5-6):299-306.
The stiffness and strength of cancellous bone depends on the amount of bone mineral (BMD) and on the three-dimensional distribution of the mineral (architecture). The relationship between mechanical properties and architecture, excluding confounding effects due to BMD can be studied using computer models of cancellous bone. It was shown that adaptation to mechanical deformation energy leads to an architecture which is an optimal or semi-optimal configuration with respect to maximal stiffness and minimal mass. Thus, the stiffness of the cancellous bone relative to the amount of bone (the bone density) can be considered as an optimality criterion. Based on these findings we assumed that the status of osteoporosis - or better fracture risk - could be related to how close this optimality criterion was met. In other words, we assumed that a higher fracture risk is simply related to a less optimal structure. This was tested for cancellous bone samples taken from post mortem vertebral bodies from two groups of subjects: one group with high fracture incidence during their lives and one group of "healthy" controls. It was found that the specimen from the high fracture incidence group had an architecture leading to a slightly stiffer structure relative to the BMD value. The conclusion is therefore that vertebral bone specimen from subjects with high fracture incidence are better optimized which was contradictory to what we expected. This finding indicates that bone specimen from the "healthy" control subjects had bone matrix at locations which are relatively unloaded. This tissue can be considered as not mechanically efficient or functional. A possible explanation of the present findings is that bone from subjects with increased fracture incidence is better adapted to mechanical stress, because it needs all bone material to carry the load. This stronger adaptation might be related to a compromised safety factor against bone loss, or diminished intrinsic matrix properties (e.g., microdamage).
松质骨的硬度和强度取决于骨矿物质的含量（骨密度）以及矿物质的三维分布（结构）。利用松质骨计算机模型，可以研究排除骨密度混杂效应后的力学性能与结构之间的关系。研究表明，对机械变形能的适应性会导致一种结构，这种结构在最大刚度和最小质量方面是最优或半最优配置。因此，松质骨相对于骨量（骨密度）的刚度可被视为一个最优性标准。基于这些发现，我们假设骨质疏松状态——或者更好地说是骨折风险——可能与满足该最优性标准的程度有关。换句话说，我们假设较高的骨折风险仅仅与结构不太优化有关。对从两组受试者的死后椎体获取的松质骨样本进行了测试：一组在生前骨折发生率高，另一组是“健康”对照组。结果发现，骨折发生率高的组的样本具有一种结构，相对于骨密度值，这种结构导致其刚度略高。因此得出的结论是，骨折发生率高的受试者的椎骨样本优化程度更高，这与我们的预期相矛盾。这一发现表明，“健康”对照组受试者的骨标本在相对未受力的位置有骨基质。这种组织可被认为在力学上效率不高或无功能。对当前研究结果的一种可能解释是，骨折发生率增加的受试者的骨骼对机械应力的适应性更好，因为它需要所有的骨材料来承载负荷。这种更强的适应性可能与抵抗骨质流失的安全系数受损或内在基质特性（如微损伤）减弱有关。
