Biomechanical Tolerance Criterion for the Spinal Cord

急性脊髓损伤(SCI)始于一种称为原发损伤的机械性损伤，随后是一种扩展的生物反应，称为继发性损伤。过去十年的研究进展表明，在动物模型中，原发损伤的特征(如加载速度、方向)对脊髓损伤的类型和严重程度有深刻的影响。对这些损伤的计算机模拟强调了这些机械效应对组织损伤的重要性。这些模拟作为伤害预防装置和环境(例如头盔和汽车内饰)的设计工具具有巨大的潜力。不幸的是，这些计算机模型作为预测工具存在局限性。需要改进的主要领域包括脊髓组织模型(例如灰质与白质、各向异性)以及将机械响应与组织损伤联系起来(即确定适当的耐受标准)。 这一发现赠款计划的总体目标是为脊髓组织确定更好的耐受标准。具体目标是确定：1)脊髓灰质和白质的准静态材料特性；2)脊髓灰质和白质的相对各向异性；以及3)力学标准(例如最大值)。主要菌株)与脊髓组织损伤最相关。这项拟议的研究是我目前NSERC发现拨款的自然发展。 为了解决这些特定的目标，将进行计算建模、活体实验和磁共振(MR)成像。为了奥贝。1和2，将使用定制的MR内SCI设备在大鼠体内产生相关的SCI，并获得变形的脊髓的MR图像。图像分析将使脐带中的应变模式估计成为可能。逆有限元(FE)方法将被用来确定灰质和白质的相对材料特性。对于Obj 3，将产生三种类型的SCI，并使用有限元模型来预测具有几个可能的容差标准的损伤模式。 按照国际标准，这项研究计划是非常新颖的。我们是使用活体模型解决生物力学变量的领导者，也是唯一能够在磁共振扫描仪的孔内产生SCI的小组。我们用计算机模拟这些损伤的能力已经得到了很好的发展，也是这项拟议研究的重要组成部分。这项研究将促进我们对脊髓组织材料特性的理解，从而提高我们在预测组织损伤方面的计算模型的质量。由于脊髓是中枢神经系统组织损伤的良好模型系统，这些结果很可能可以转化为脑损伤。这将有助于设计环境(例如，车内)，以防止脊柱和脊髓损伤。我们为HQP提供了丰富的跨学科培训环境，我们希望在这个时间框架内培训两名硕士和两名博士生。

Acute spinal cord injury (SCI) begins with a mechanical insult, termed primary injury, followed by an extended biological response, called secondary injury. Research advances over the past decade show, in animal models, that features of the primary injury (e.g. loading rate, direction) have profound influences on the pattern and severity of SCI. Computer simulations of these injuries emphasized the importance of these mechanical effects on tissue damage. These simulations have great potential as design tools for devices and environments for injury prevention (e.g. helmets and automobile interiors). Unfortunately, there exist limitations with these computer models as predictive tools. The main areas for improvement include spinal cord tissue modelling (e.g. grey vs. white matter, anisotropy) and relating the mechanical response to tissue damage (i.e. identifying an appropriate tolerance criterion). The overall goal of this Discovery Grant program is to determine better tolerance criteria for spinal cord tissue. The specific objectives are to determine the: 1) quasi-static material properties of spinal cord grey and white matter; 2) relative anisotropy of spinal cord grey and white matter; and 3) mechanical criteria (e.g. max. principal strain) that best correlate with spinal cord tissue damage. The proposed research is a natural progression of my current NSERC Discovery Grant. To address these specific objectives, computational modelling, in vivo experiments, and magnetic resonance (MR) imaging will be conducted. For Obj. 1 and 2, relevant SCIs will be produced in vivo in rats using a custom intra-MR SCI device and MR images obtained of the deformed spinal cords. Image analysis will enable strain pattern estimation in the cord. Inverse finite element (FE) approaches will be used to determine the relative material properties of the grey and white matter. For Obj 3, three types of SCIs will be produced and the FE model used to predict damage patterns with several possible tolerance criteria. This research program is highly novel by international standards. We are leaders in addressing the biomechanical variables using an in vivo model, and the only group able to produce SCIs inside the bore of an MR scanner. Our ability to computationally model these injuries is well developed and an important component of this proposed research. This research will advance our understanding of the material properties of spinal cord tissue and thus will enhance the quality of our computational models in predicting tissue damage. As the spinal cord is a good model system for injury to central nervous system tissue, these results are likely translatable to brain injury. This will aid the design of environments (e.g. inside of a car) for the prevention of spine and spinal cord injuries. We have a rich, interdisciplinary training environment for HQP and we expect to train two MASc and two PhD students in this timeframe.