Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
Bone. 2011 Jun 1;48(6):1232-8. doi: 10.1016/j.bone.2011.02.022. Epub 2011 Mar 2.
High-resolution peripheral quantitative computed tomography (HR-pQCT) is clinically available today and provides a non-invasive measure of 3D bone geometry and micro-architecture with unprecedented detail. In combination with microarchitectural finite element (μFE) models it can be used to determine bone strength using a strain-based failure criterion. Yet, images from only a relatively small part of the radius are acquired and it is not known whether the region recommended for clinical measurements does predict forearm fracture load best. Furthermore, it is questionable whether the currently used failure criterion is optimal because of improvements in image resolution, changes in the clinically measured volume of interest, and because the failure criterion depends on the amount of bone present. Hence, we hypothesized that bone strength estimates would improve by measuring a region closer to the subchondral plate, and by defining a failure criterion that would be independent of the measured volume of interest. To answer our hypotheses, 20% of the distal forearm length from 100 cadaveric but intact human forearms was measured using HR-pQCT. μFE bone strength was analyzed for different subvolumes, as well as for the entire 20% of the distal radius length. Specifically, failure criteria were developed that provided accurate estimates of bone strength as assessed experimentally. It was shown that distal volumes were better in predicting bone strength than more proximal ones. Clinically speaking, this would argue to move the volume of interest for the HR-pQCT measurements even more distally than currently recommended by the manufacturer. Furthermore, new parameter settings using the strain-based failure criterion are presented providing better accuracy for bone strength estimates.
高分辨率外周定量计算机断层扫描（HR-pQCT）目前在临床上可用，它提供了一种非侵入性的三维骨几何形状和微观结构测量方法，具有前所未有的细节。结合微观结构有限元（μFE）模型，可以使用基于应变的失效准则来确定骨强度。然而，仅获取了相对较小部分桡骨的图像，并且尚不清楚推荐用于临床测量的区域是否能最好地预测前臂骨折负荷。此外，由于图像分辨率的提高、临床测量感兴趣体积的变化，以及失效准则取决于存在的骨量，目前使用的失效准则是否最优仍存在疑问。因此，我们假设通过测量更接近软骨下板的区域，并定义一个与测量的感兴趣体积无关的失效准则，骨强度估计值将会提高。为了验证我们的假设，使用 HR-pQCT 对 100 具完整但无关节的人体前臂的 100 具尸体前臂的 20%的远端前臂长度进行了测量。针对不同的子体积以及整个 20%的远端桡骨长度，对 μFE 骨强度进行了分析。具体而言，开发了失效准则，为骨强度提供了与实验评估准确相符的估计值。结果表明，远端体积比近端体积更能预测骨强度。从临床角度来看，这将证明需要将 HR-pQCT 测量的感兴趣体积比制造商目前推荐的更向远端移动。此外，还提出了新的基于应变的失效准则参数设置，为骨强度估计提供了更好的准确性。
