To better understand the link between spinal cord impact and the resulting tissue damage, computational models are often used. These models typically simulate the spinal cord as a homogeneous and isotropic material. Recent research suggests that grey and white matter tissue differences and directional differences, i.e. anisotropy, are important to predict spinal cord damage. The objective of this research was to characterize the mechanical properties of spinal cord grey and white matter tissue in confined compression.

Spinal cords (n = 12) were harvested immediately following euthanasia from Yorkshire and Yucatan pigs. The spinal cords were flash frozen (60 s at -80 °C) and prepared into four types of test samples: grey matter axial, grey matter transverse, white matter axial, and white matter transverse. Each sample type was thawed, and subsequently tested in confined compression within 6 h of euthanasia. Samples were compressed to 10% strain at a quasi-static strain rate (0.001/sec) and allowed to relax for 120 s. A quasi-linear viscoelastic model combining a first-order exponential with a 1-term Prony series characterized the loading and relaxation responses respectively. The effect of tissue type (grey matter vs. white matter), direction (axial vs. transverse), and their interaction were evaluated with a two-way ANOVA (p < 0.05) with peak stress, aggregate modulus, and relaxation time as dependent variables.

This study found grey matter to be 1.6–2 times stiffer than white matter and both grey and white matter were isotropic in compression. These findings should be emphasized when studying SCI biomechanics using computational models.

为了更好地理解脊髓撞击与组织损伤之间的联系，经常使用计算模型。这些模型通常将脊髓模拟为均质且各向同性的材料。最近的研究表明，灰色和白色物质的组织差异和方向差异（即各向异性）对于预测脊髓损伤很重要。这项研究的目的是表征有限压迫下脊髓灰质和白质组织的力学性能。

安乐死后立即从约克郡和尤卡坦州的猪中收获脊髓（n = 12）。将脊髓速冻（-80°C下60 s），并准备成四种类型的测试样品：轴向灰质，横向灰质，轴向白质和横向白质。解冻每种样品，然后在安乐死的6小时内进行有限压缩测试。将样品以准静态应变率（0.001 / sec）压缩至10％应变，并松弛120 s。结合一阶指数和1项Prony级数的准线性粘弹性模型，分别描述了载荷和松弛响应。组织类型（灰质相对于白质），方向（轴向相对于横向）及其相互作用的影响是通过双向方差分析（p <0.05）在峰值应力下进行评估的，

这项研究发现，灰质的刚度是白质的1.6–2倍，而灰质和白质在压缩时各向同性。使用计算模型研究SCI生物力学时应强调这些发现。