INSERM Research Unit 831, Université de Lyon, Lyon, France.
J Bone Miner Res. 2010 Nov;25(11):2324-31. doi: 10.1002/jbmr.164.
Low bone mineral density (BMD) is a strong risk factor for vertebral fracture risk in osteoporosis. However, many fractures occur in people with moderately decreased or normal BMD. Our aim was to assess the contributions of trabecular microarchitecture and its heterogeneity to the mechanical behavior of human lumbar vertebrae. Twenty-one human L(3) vertebrae were analyzed for BMD by dual-energy X-ray absorptiometry (DXA) and microarchitecture by high-resolution peripheral quantitative computed tomography (HR-pQCT) and then tested in axial compression. Microarchitecture heterogeneity was assessed using two vertically oriented virtual biopsies--one anterior (Ant) and one posterior (Post)--each divided into three zones (superior, middle, and inferior) and using the whole vertebral trabecular volume for the intraindividual distribution of trabecular separation (Tb.Sp*SD). Heterogeneity parameters were defined as (1) ratios of anterior to posterior microarchitectural parameters and (2) the coefficient of variation of microarchitectural parameters from the superior, middle, and inferior zones. BMD alone explained up to 44% of the variability in vertebral mechanical behavior, bone volume fraction (BV/TV) up to 53%, and trabecular architecture up to 66%. Importantly, bone mass (BMD or BV/TV) in combination with microarchitecture and its heterogeneity improved the prediction of vertebral mechanical behavior, together explaining up to 86% of the variability in vertebral failure load. In conclusion, our data indicate that regional variation of microarchitecture assessment expressed by heterogeneity parameters may enhance prediction of vertebral fracture risk.
骨密度（BMD）低是骨质疏松症椎体骨折风险的一个重要危险因素。然而，许多骨折发生在 BMD 中度降低或正常的人群中。我们的目的是评估骨小梁微观结构及其异质性对人类腰椎力学行为的贡献。通过双能 X 射线吸收法（DXA）对 21 个人类 L(3)椎体进行 BMD 分析，通过高分辨率外周定量 CT（HR-pQCT）进行微观结构分析，然后进行轴向压缩测试。使用两个垂直定向的虚拟活检（一个前向（Ant）和一个后向（Post））评估微观结构异质性，每个活检分为三个区域（上部、中部和下部），并使用整个椎体小梁体积来评估小梁分离（Tb.Sp*SD）的个体内分布。异质性参数定义为：（1）前向后微观结构参数的比值，（2）来自上部、中部和下部区域的微观结构参数的变异系数。BMD 单独解释了 44%的椎体力学行为的可变性，骨体积分数（BV/TV）解释了 53%，骨小梁结构解释了 66%。重要的是，骨量（BMD 或 BV/TV）与微观结构及其异质性的结合提高了对椎体力学行为的预测能力，共同解释了 86%的椎体失效负荷的可变性。总之，我们的数据表明，用异质性参数表达的微观结构评估的区域变化可能会增强对椎体骨折风险的预测。
