Foreword: Calcified Tissue International and Musculoskeletal Research Special Issue: Bone Material Properties and Skeletal Fragility.
Foreword: Calcified Tissue International and Musculoskeletal Research Special Issue: Bone Material Properties and Skeletal Fragility.
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前言：钙化组织国际和肌肉骨骼研究特刊：骨材料特性和骨骼脆弱性。
DOI：
10.1007/s00223-015-0012-7
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发表时间：
2015
影响因子：
4.2
通讯作者：
Allen,MatthewR
中科院分区：
文献类型：
--
作者：
Burr,DavidB;Allen,MatthewR
骨骼脆弱性以及在很大程度上骨折的风险取决于骨骼的三个一般特性：骨骼的数量（质量）、骨骼质量的分布方式（结构/几何形状）以及构成骨骼的组织的材料特性（矿物质、胶原蛋白、非胶原蛋白的特性、骨骼水合以及这些成分之间的相互作用）（图 1）。在这三个广泛的特征中，骨量作为骨折的预测因子受到了最大的关注，很大程度上是因为它在临床环境中最容易测量。 DEXA 骨矿物质密度 (BMD) 测量值已成为骨骼健康的标准测量值，并且单独用作病理学定义：如果 BMD 比白种女性年轻成人平均值低 2.5 个标准差以上，则诊断为骨质疏松症，无论骨骼的其他代偿特征是否可能抵消较低的 BMD。即便如此，大多数研究骨骼的科学家都了解结构的重要性，包括小梁晶格的连通性，以及皮质宽度、厚度和孔隙率对骨骼刚性的重要性。结构特征并不完全独立于骨量（例如，骨质流失会影响小梁的连接性），但它们可以是（即使骨量下降，截面模量也会增加）。因此，BMD 并不能提供骨折风险的完整情况。此外，结构特征在临床环境中更难以测量，直到最近才将它们与 BMD 结合使用来尝试评估骨折风险。其中一个例子是最近使用的骨小梁评分 (TBS)，它将小梁纹理分析与 BMD 值相结合。骨骼材料本身的特性所发挥的作用，与骨骼的数量或分布方式无关，很少受到关注。造成这种情况的原因有很多。一是在没有活检的情况下临床测量材料变化的固有困难。另一个是我们的测量技术在评估骨骼中各种矿物质、胶原蛋白和水室发生的微观结构和纳米结构变化方面的历史局限性。然而，允许测量体内骨材料机械性能的新技术的发展可能会引导我们进入一个这样的时代：这些性能的测量可以有助于临床决策。此外，表征骨基质各个成分的成像和测量技术的改进，如原子力显微镜、广角和小角度 X 射线散射、超短回波时间 MRI 等，有助于更好地了解骨的纳米结构形态和生理学。这些技术为改进分层计算模型打开了大门，在对材料本身有一定了解的情况下，这些模型可以预测机械行为。我们仍处于探索阶段，了解骨骼的材料特性是否以及如何真正赋予骨骼显着的弹性或脆性，以及如何利用这些信息来获得临床益处。现在似乎是时候回顾一下我们对骨组织特性的了解、如何测量它们以及为什么它们对骨骼完整性可能很重要。本期《钙化组织国际和肌肉骨骼研究》特刊首先概述了分子和组织水平
Skeletal fragility, and to a large extent the risk of fracture, is dependent on three general properties of a bone: the amount of bone (mass), the way the mass is distributed (architecture/geometry), and the material properties (characteristics of the mineral, collagen, noncollagenous proteins, skeletal hydration, and interaction among these constituents) of the tissue that compose the bone (Fig. 1). Of these three broad characteristics, bone mass has received the greatest attention as a predictor of fracture in large part because it is the easiest to measure in a clinical setting. DEXA measurements of bone mineral density (BMD) have become the standard measure of skeletal health, and alone are used as the definition for pathology: one is diagnosed with osteoporosis if the BMD is greater than 2.5 standard deviations below the young adult mean for a Caucasian woman, regardless of other compensatory characteristics of the bone that may offset the lower BMD. Even so, most scientists who study bone understand the importance of architecture, both the connectivity of the trabecular lattice, as well as the importance of cortical width, thickness, and porosity to bone’s rigidity. Architectural features are not completely independent of bone mass (eg, loss of bone will affect trabecular connectivity), but they can be (section modulus can increase even as bone mass declines). Thus, BMD does not provide a complete picture of fracture risk. Moreover, architectural features are more difficult to measure in a clinical setting and only recently have they been utilized, in combination with BMD, to try to assess fracture risk. One example of this is the recent use of the trabecular bone score (TBS), which integrates trabecular texture analysis with BMD values. The role that the properties of the bone material itself play, independent of how much bone one has or how it is distributed, has received little attention. There are multiple reasons for this. One is the inherent difficulty of measuring material changes clinically without a biopsy. Another is the historic limitations of our measurement techniques to assess the microstructural and nano-structural changes that occur to the various mineral, collagen, and water compartments in bone. However, the development of new technologies that allow measurement of bone material mechanical properties in vivo may be leading us to a time when measurements of these properties can contribute to clinical decisions. Also, improvements in imaging and measurement technologies that characterize individual components of the bone matrix, such as atomic force microscopy, wide-and small angle X-ray scattering, ultrashort echo time MRI, and others, are contributing to a better understanding of the nanostructural morphology and physiology of bone. These technologies have opened the door to improved hierarchical computational models that can predict mechanical behavior given some knowledge of the material itself.We are still in the exploratory phases of understanding whether and how the material properties of bone really can impart significant resilience or fragility to the skeleton, and how to use this information for clinical benefit. The time seems appropriate to review what we know of bone tissue properties, how they are measured, and why they may be important to skeletal integrity. This special issue of Calcified Tissue International and Musculoskeletal Research begins with an overview of the molecular and tissue level