Dragomir-Daescu Dan, Salas Christina, Uthamaraj Susheil, Rossman Timothy
Division of Engineering, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, United States; Mayo Clinic College of Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, United States.
Division of Engineering, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, United States; Department of Orthopaedics, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, United States.
J Biomech. 2015 Jan 2;48(1):153-61. doi: 10.1016/j.jbiomech.2014.09.016. Epub 2014 Sep 28.
The aim of the present study was to compare proximal femur strength and stiffness obtained experimentally with estimations from Finite Element Analysis (FEA) models derived from Quantitative Computed Tomography (QCT) scans acquired at two different scanner settings. QCT/FEA models could potentially aid in diagnosis and treatment of osteoporosis but several drawbacks still limit their predictive ability. One potential reason is that the models are still sensitive to scanner settings which could lead to changes in assigned material properties, thus limiting their results accuracy and clinical effectiveness. To find the mechanical properties we fracture tested 44 proximal femora in a sideways fall-on-the-hip configuration. Before testing, we CT scanned all femora twice, first at high resolution scanner settings, and second at low resolution scanner settings and built 88 QCT/FEA models of femoral strength and stiffness. The femoral set neck bone mineral density, as measured by DXA, uniformly covered the range from osteoporotic to normal. This study showed that the femoral strength and stiffness values predicted from high and low resolution scans were significantly different (p<0.0001). Strength estimated from high resolution QCT scans was larger for osteoporotic, but smaller for normal and osteopenic femora when compared to low resolution scans. In addition, stiffness estimated from high resolution scans was consistently larger than stiffness obtained from low resolution scans over the entire femoral dataset. While QCT/FEA techniques hold promise for use in clinical settings we provided evidence that further improvements are required to increase robustness in their predictive power under different scanner settings and modeling assumptions.
本研究的目的是将通过实验获得的股骨近端强度和刚度与基于在两种不同扫描仪设置下采集的定量计算机断层扫描（QCT）扫描数据所构建的有限元分析（FEA）模型的估计值进行比较。QCT/FEA模型可能有助于骨质疏松症的诊断和治疗，但仍有几个缺点限制了它们的预测能力。一个潜在原因是这些模型对扫描仪设置仍然敏感，这可能导致所分配材料属性的变化，从而限制了其结果的准确性和临床有效性。为了确定力学性能，我们以侧方臀部着地的姿势对44根股骨近端进行了骨折测试。在测试之前，我们对所有股骨进行了两次CT扫描，第一次在高分辨率扫描仪设置下进行，第二次在低分辨率扫描仪设置下进行，并构建了88个关于股骨强度和刚度的QCT/FEA模型。通过双能X线吸收法（DXA）测量的股骨颈骨矿物质密度均匀覆盖了从骨质疏松到正常的范围。本研究表明，从高分辨率和低分辨率扫描预测的股骨强度和刚度值存在显著差异（p<0.0001）。与低分辨率扫描相比，从高分辨率QCT扫描估计的骨质疏松性股骨强度更大，但正常和骨量减少性股骨的强度更小。此外，在整个股骨数据集中，从高分辨率扫描估计的刚度始终大于从低分辨率扫描获得的刚度。虽然QCT/FEA技术在临床应用中有前景，但我们提供的证据表明，需要进一步改进以提高其在不同扫描仪设置和建模假设下预测能力的稳健性。
