Kroker Andres, Plett Ryan, Nishiyama Kyle K, McErlain David D, Sandino Clara, Boyd Steven K
Department of Radiology, Cumming School of Medicine, University of Calgary, Canada; McCaig Institute for Bone and Joint Health, University of Calgary, Canada.
McCaig Institute for Bone and Joint Health, University of Calgary, Canada.
J Biomech. 2017 Jul 5;59:43-49. doi: 10.1016/j.jbiomech.2017.05.011. Epub 2017 May 18.
Dual energy X-ray absorptiometry (DXA) is the standard for assessing fragility fracture risk using areal bone mineral density (aBMD), but only explains 60-70% of the variation in bone strength. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides 3D-measures of bone microarchitecture and volumetric bone mineral density (vBMD), but only at the wrist and ankle. Finite element (FE) models can estimate bone strength with 86-95% precision. The purpose of this study is to determine how well vBMD and FE bone strength at the wrist and ankle relate to fracture strength at the hip and spine, and to compare these relationships with DXA measured directly at those axial sites. Cadaveric samples (radius, tibia, femur and L4 vertebra) were compared within the same body. The radius and tibia specimens were assessed using HR-pQCT to determine vBMD and FE failure load. aBMD from DXA was measured at the femur and L4 vertebra. The femur and L4 vertebra specimens were biomechanically tested to determine failure load. aBMD measures of the axial skeletal sites strongly correlated with the biomechanical strength for the L4 vertebra (r=0.77) and proximal femur (r=0.89). The radius correlated significantly with biomechanical strength of the L4 vertebra for vBMD (r=0.85) and FE-derived strength (r=0.72), but not with femur strength. vBMD at the tibia correlated significantly with femoral biomechanical strength (r=0.74) and FE-estimated strength (r=0.83), and vertebral biomechanical strength for vBMD (r=0.97) and FE-estimated strength (r=0.91). The higher correlations at the tibia compared to radius are likely due to the tibia's weight-bearing function.
双能X线吸收法（DXA）是使用面积骨密度（aBMD）评估脆性骨折风险的标准方法，但它只能解释60%-70%的骨强度变化。高分辨率外周定量计算机断层扫描（HR-pQCT）可提供骨微结构和体积骨密度（vBMD）的三维测量，但仅适用于手腕和脚踝部位。有限元（FE）模型能够以86%-95%的精度估算骨强度。本研究的目的是确定手腕和脚踝部位的vBMD及FE骨强度与髋部和脊柱骨折强度的关联程度，并将这些关联与在这些轴向部位直接测量的DXA进行比较。在同一具尸体上比较了尸体样本（桡骨、胫骨、股骨和L4椎体）。使用HR-pQCT对桡骨和胫骨样本进行评估，以确定vBMD和FE破坏载荷。在股骨和L4椎体处测量DXA的aBMD。对股骨和L4椎体样本进行生物力学测试以确定破坏载荷。轴向骨骼部位的aBMD测量值与L4椎体（r=0.77）和股骨近端（r=0.89）的生物力学强度密切相关。桡骨的vBMD（r=0.85）和FE衍生强度（r=0.72）与L4椎体的生物力学强度显著相关，但与股骨强度无关。胫骨的vBMD与股骨生物力学强度（r=0.74）和FE估计强度（r=0.83）以及vBMD的椎体生物力学强度（r=0.97）和FE估计强度（r=0.91）显著相关。与桡骨相比，胫骨处的相关性更高可能是由于胫骨的负重功能。
