有限元模型在预测体外椎体抗压强度方面比定量计算机断层扫描表现更好。

Finite element models predict in vitro vertebral body compressive strength better than quantitative computed tomography.

作者信息

Crawford R Paul, Cann Christopher E, Keaveny Tony M

机构信息

Department of Mechanical Engineering, University of California, Berkeley, CA 94720-1740, USA.

出版信息

Bone. 2003 Oct;33(4):744-50. doi: 10.1016/s8756-3282(03)00210-2.

Abstract

The correlation between bone mineral density and vertebral strength is not based on mechanical principles and thus the method cannot reflect the effects of subtle geometric features and densitometric inhomogeneities that may substantially affect vertebral strength. Finite element models derived from quantitative computed tomography (QCT) scans overcome such limitations. The overall goal of this study was to establish that QCT-based "voxel" finite element models are better predictors of vertebral compressive strength than QCT measures of bone mineral density with or without measures of cross-sectional area. QCT scans were taken of 13 vertebral bodies excised from 13 cadavers (L1-L4; age: 37-87 years; M = 6, F = 7) and used to calculate bone mineral density (BMD(QCT)). The QCT voxel data were converted into linearly elastic finite element models of each vertebra, from which measures of vertebral stiffness and strength were computed. The vertebrae were biomechanically tested in compression to measure strength. Vertebral strength was positively correlated with the finite element measures of strength (r(2) = 0.86, P < 0.0001) and stiffness (r(2) = 0.82, P < 0.0001), the product of BMD(QCT) and vertebral minimum cross-sectional area (r(2) = 0.65, P = 0.0008), and BMD(QCT) alone (r(2) = 0.53, P = 0.005). These results demonstrate that highly automated "voxel" finite element models are superior to correlation-based QCT methods in predicting vertebral compressive strength and therefore offer great promise for improvement of clinical fracture risk assessment.

摘要

骨矿物质密度与椎体强度之间的相关性并非基于力学原理,因此该方法无法反映可能对椎体强度产生重大影响的细微几何特征和密度测量不均匀性的影响。源自定量计算机断层扫描(QCT)扫描的有限元模型克服了这些局限性。本研究的总体目标是确定基于QCT的“体素”有限元模型在预测椎体抗压强度方面比有或没有测量横截面积的骨矿物质密度的QCT测量方法更好。对从13具尸体(L1-L4;年龄:37-87岁;男性=6,女性=7)切除的13个椎体进行QCT扫描,并用于计算骨矿物质密度(BMD(QCT))。将QCT体素数据转换为每个椎体的线性弹性有限元模型,从中计算椎体刚度和强度的测量值。对椎体进行压缩生物力学测试以测量强度。椎体强度与强度的有限元测量值(r(2)=0.86,P<0.0001)和刚度(r(2)=0.82,P<0.0001)、BMD(QCT)与椎体最小横截面积的乘积(r(2)=0.65,P=0.0008)以及单独的BMD(QCT)(r(2)=0.53,P=0.005)呈正相关。这些结果表明,高度自动化的“体素”有限元模型在预测椎体抗压强度方面优于基于相关性的QCT方法,因此在改善临床骨折风险评估方面具有很大的前景。

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