Nyman Jeffry S, Granke Mathilde, Singleton Robert C, Pharr George M
Department of Orthopaedic Surgery and Rehabilitation, Vanderbilt University Medical Center, 1215 21st Ave. S., South Tower, Suite 4200, Nashville, TN, 37232, USA.
Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, 37212, USA.
Curr Osteoporos Rep. 2016 Aug;14(4):138-50. doi: 10.1007/s11914-016-0314-3.
Tissue-level mechanical properties characterize mechanical behavior independently of microscopic porosity. Specifically, quasi-static nanoindentation provides measurements of modulus (stiffness) and hardness (resistance to yielding) of tissue at the length scale of the lamella, while dynamic nanoindentation assesses time-dependent behavior in the form of storage modulus (stiffness), loss modulus (dampening), and loss factor (ratio of the two). While these properties are useful in establishing how a gene, signaling pathway, or disease of interest affects bone tissue, they generally do not vary with aging after skeletal maturation or with osteoporosis. Heterogeneity in tissue-level mechanical properties or in compositional properties may contribute to fracture risk, but a consensus on whether the contribution is negative or positive has not emerged. In vivo indentation of bone tissue is now possible, and the mechanical resistance to microindentation has the potential for improving fracture risk assessment, though determinants are currently unknown.
组织水平的力学性能表征了独立于微观孔隙率的力学行为。具体而言，准静态纳米压痕可在薄片长度尺度上测量组织的模量（刚度）和硬度（抗屈服能力），而动态纳米压痕则以储能模量（刚度）、损耗模量（阻尼）和损耗因子（两者之比）的形式评估随时间变化的行为。虽然这些特性有助于确定感兴趣的基因、信号通路或疾病如何影响骨组织，但它们通常不会随着骨骼成熟后的衰老或骨质疏松症而变化。组织水平力学性能或组成特性的异质性可能会导致骨折风险增加，但对于这种影响是负面还是正面尚未达成共识。目前可以对骨组织进行体内压痕测量，尽管目前尚不清楚其决定因素，但微压痕的力学阻力有改善骨折风险评估的潜力。
