Department of Orthopaedics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China.
Chin Med J (Engl). 2009 Sep 5;122(17):2041-7.
With advance of age, alterations in bone quality, quantity and microarchitecture render osteoporotic trabecular bone become more sensitive to local failure. The aims of the present study were to clarify the extent to which the distribution of tissue-level stresses and strains was affected by structural changes and the extent to which osteoporotic acetabular trabecular bone was damaged at small strains.
Using a DAWING 4000A supercomputer, nonlinear micro-finite element (microFE) analyses were performed to calculate the tissue-level strains and stresses for each element in the trabecular bone of one osteoporotic acetabulum at small strains to quantify the tissue-level damage accumulation and mechanical properties.
In contour plots of the tissue, maximum principal logarithmic strains, high tissue-level strains, both compressive and tensile, were observed in the osteoporotic trabecular bone at small apparent strains from 0.2% to 0.5% strain. The compressive apparent stress-strain curve showed typical nonlinear behavior and tangent modulus reduction with increasing strains. The microdamage curve suggested that microdamage began at 0.2% apparent strain in the osteoporotic trabecular bone and increased sharply, although very few microfractures occurred. The quartiles of the maximum principal logarithmic strains, minimum principal logarithmic strains and Von Mises stresses increased nonlinearly. For the inter-quartile range of the Von Mises stresses, a leap occurred at small strains ranging from 0.2% to 0.3% while microdamage commenced.
Extensive microdamage was primarily responsible for the large loss in apparent mechanical properties that occurred in the trabecular bone of the osteoporotic acetabulum at small strains. With increasing apparent strains, continuous nonlinear increments of tissue-level strains and stresses resulted in microdamage that propagated throughout the specimen with very few microfractures.
随着年龄的增长，骨质量、数量和微结构的改变使骨质疏松小梁骨对局部失效更加敏感。本研究旨在阐明结构变化对组织水平应变和应变分布的影响程度，以及小应变时骨质疏松髋臼小梁骨受损的程度。
利用 DAWING 4000A 超级计算机，对一个骨质疏松髋臼的小梁骨进行非线性微有限元（microFE）分析，以计算每个单元的组织水平应变和应力，从而量化组织水平的损伤积累和力学性能。
在组织等高线图中，在小表观应变（0.2%至 0.5%）下，骨质疏松小梁骨中观察到最大主对数应变、高组织水平应变（压缩和拉伸）。压缩表观应力-应变曲线表现出典型的非线性行为和随应变增加的切线模量降低。微损伤曲线表明，在骨质疏松小梁骨中，微损伤始于 0.2%的表观应变，并急剧增加，尽管很少发生微裂缝。最大主对数应变、最小主对数应变和 Von Mises 应力的四分位数呈非线性增加。对于 Von Mises 应力的四分位间距，在微损伤开始的小应变范围内（0.2%至 0.3%）出现跃升。
在小应变时，骨质疏松髋臼小梁骨的表观力学性能发生了很大的损失，主要是由于广泛的微损伤所致。随着表观应变的增加，组织水平应变和应力的连续非线性增加导致微损伤在整个标本中传播，很少发生微裂缝。
