The Prospects of Estimating Trabecular Bone Tissue Properties from the Combination of Ultrasound, Dual-Energy X-Ray Absorptiometry, Microcomputed Tomography, and Microfinite Element Analysis
作者:G. H. Van Lenthe、J. P. W. Van Den Bergh、A. R. M. M. Hermus、R. Huiskes
DOI:10.1359/jbmr.2001.16.3.550
日期:——
Osteoporosis commonly is assessed by bone quantity, using bone mineral density (BMD) measurements from dual‐energy X‐ray absorptiometry (DXA). However, such a measure gives neither information about the integrity of the trabecular architecture nor about the mechanical properties of the constituting trabeculae. We investigated the feasibility of deriving the elastic modulus of the trabeculae (the tissue modulus) from computer simulation of mechanical testing by microfinite element analysis (μFEA) in combination with measurements of ultrasound speed of sound (SOS) and BMD measurements. This approach was tested on 15 postmortem bovine bone cubes. The apparent elastic modulus of the specimens was estimated from SOS measurements in combination with BMD. Then the trabecular morphology was reconstructed using microcomputed tomography (μCT). From the reconstruction a mesh for μFEA was derived, used to simulate mechanical testing. The tissue modulus was found by correlating the apparent moduli of the specimens as assessed by ultrasound with the ones as determined with μFEA. A mean tissue modulus of 4.5 GPa (SD, 0.69) was found. When adjusting the μFEA‐determined elastic moduli of the entire specimens with their calculated tissue modulus, an overall correlation of R2 = 96% with ultrasound‐predicted values was obtained. We conclude that the apparent elastic stiffness characteristics as determined from ultrasound correlate linearly with those from μFEA. From both methods in combination, the elastic stiffness of the mineralized tissue can be determined as an estimator for mechanical tissue quality. This method can already be used for biopsy specimens, and potentially could be applicable in vivo as well, when clinical CT or magnetic resonance imaging (MRI) tools with adequate resolution reach the market. In this way, mechanical bone quality could be estimated more accurately in clinical practice.
骨质疏松症通常通过骨量评估,使用双能X射线吸收法(DXA)测量骨矿物质密度(BMD)。然而,这种测量方法既不能提供小梁结构的完整性信息,也无法反映构成小梁的机械特性。我们研究了通过微有限元分析(μFEA)结合超声速(SOS)测量和BMD测量来推导小梁的弹性模量(组织模量)的可行性。该方法在15个死亡后牛骨立方体上进行了测试。通过结合BMD的SOS测量估算样本的表观弹性模量。然后,使用微计算机断层扫描(μCT)重建小梁形态。从重建中导出用于μFEA的网格,以模拟机械测试。通过将超声评估的样本表观模量与μFEA确定的模量进行相关,得出了组织模量。发现平均组织模量为4.5 GPa(标准差0.69)。在调整整个样本的μFEA确定的弹性模量与其计算的组织模量时,获得了超声预测值的整体相关性R² = 96%。我们得出结论,从超声确定的表观弹性刚度特性与μFEA的结果呈线性相关。结合这两种方法,可以作为机械组织质量的估算指标来确定矿化组织的弹性刚度。该方法已经可以用于活检样本,并且在临床CT或具有足够分辨率的磁共振成像(MRI)工具上市后,可能也适用于体内检测。通过这种方式,可以在临床实践中更准确地估计骨的机械质量。