Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801, USA.
J Biomech. 2011 Jan 11;44(2):313-20. doi: 10.1016/j.jbiomech.2010.10.011. Epub 2010 Oct 30.
Multi-scale experimental work was carried out to characterize cortical bone as a heterogeneous material with hierarchical structure, which spans from nanoscale (mineralized collagen fibril), sub-microscale (single lamella), microscale (lamellar structures), to mesoscale (cortical bone) levels. Sections from femoral cortical bone from 6, 12, and 42 months old swine were studied to quantify the age-related changes in bone structure, chemical composition, and mechanical properties. The structural changes with age from sub-microscale to mesoscale levels were investigated with scanning electron microscopy and micro-computed tomography. The chemical compositions at mesoscale were studied by ash content method and dual energy X-ray absorptiometry, and at microscale by Fourier transform infrared microspectroscopy. The mechanical properties at mesoscale were measured by tensile testing, and elastic modulus and hardness at sub-microscale were obtained using nanoindentation. The experimental results showed age-related changes in the structure and chemical composition of cortical bone. Lamellar bone was a prevalent structure in 6 months and 12 months old animals, resorption sites were most pronounced in 6 months old animals, while secondary osteons were the dominant features in 42 months old animals. Mineral content and mineral-to-organic ratio increased with age. The structural and chemical changes with age corresponded to an increase in local elastic modulus, and overall elastic modulus and ultimate tensile strength as bone matured.
进行了多尺度实验工作，以表征皮质骨作为具有层次结构的多相材料，其范围从纳米尺度（矿化胶原纤维）、亚微观尺度（单个板层）、微观尺度（板层结构）到中等尺度（皮质骨）。研究了来自 6 个月、12 个月和 42 个月大的猪的股骨皮质骨切片，以量化与年龄相关的骨结构、化学成分和机械性能变化。通过扫描电子显微镜和微计算机断层扫描研究了亚微观到中等尺度水平的年龄相关结构变化。通过灰分法和双能 X 射线吸收法研究了中等尺度的化学成分，通过傅里叶变换红外微光谱法研究了微观尺度的化学成分。通过拉伸试验测量了中等尺度的机械性能，通过纳米压痕测量了亚微观尺度的弹性模量和硬度。实验结果表明皮质骨的结构和化学成分随年龄而变化。板层骨是 6 个月和 12 个月大动物的常见结构，吸收部位在 6 个月大动物中最为明显，而二次骨单位是 42 个月大动物的主要特征。矿物质含量和矿物质与有机物的比例随年龄增加而增加。年龄相关的结构和化学成分变化与局部弹性模量的增加相对应，随着骨成熟，整体弹性模量和极限拉伸强度也增加。
