Modeling the effects of hydration on viscoelastic properties of nucleus pulposus tissue in shear using the fractional Zener model.
Modeling the effects of hydration on viscoelastic properties of nucleus pulposus tissue in shear using the fractional Zener model.
复制标题
使用分数齐纳模型模拟水合对剪切下髓核组织粘弹性的影响。
DOI：
10.1016/j.jbiomech.2024.111965
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发表时间：
2024
影响因子：
2.4
通讯作者：
Walter,BenjaminA
中科院分区：
文献类型：
--
作者：
Co,Megan;Pack,Chelsea;Osborn-King,Zachary;Raterman,Brian;Kolipaka,Arunark;Bentil,SarahA;Walter,BenjaminA
椎间盘 (IVD) 中的髓核 (NP) 组织是一种粘弹性材料，表现出类似固体和液体的机械行为。结合分数阶微积分的粘弹性模型的进展，例如分数齐纳 (FZ) 模型，有可能描述粘弹性行为。本研究的目的是确定 FZ 模型是否能够准确描述 NP 组织的剪切粘弹性特性，并确定分数阶 (α) 是否与组织水化有关。 30 个尾部 IVD 在 5% 或 25% 聚乙二醇溶液中进行平衡透析，以改变组织水合。切除的 NP 组织在剪切和无侧限压缩下进行应力松弛测试。将应力松弛数据拟合到 FZ 模型以获得粘弹性。在两种加载模式下，与平衡模量没有变化的 5% 样品相比，水合程度较低的 25% 平衡样品的初始模量更大。含水量较低的样品（25% 样品）在剪切时具有较短的弛豫时间，在压缩时具有较长的时间常数，突出了加载模式下流体和固体基质之间的不同相互作用。含水量较低的样品的 α 值接近 0，表明含水量较少的样品在粘弹性谱上表现得更像固体。组织水合作用与剪切中 25% 样品的 α 值相关。这项研究表明，FZ 模型可用于描述两种加载模式下的 IVD 组织行为；然而，FZ 模型的最大用途是描述与流动无关的剪切行为，并且 α 可以告知剪切中的组织水合作用。
Nucleus pulposus (NP) tissue in the intervertebral disc (IVD) is a viscoelastic material exhibiting both solid- and fluid-like mechanical behaviors. Advances in viscoelastic models incorporating fractional calculus, such as the Fractional Zener (FZ) model, have potential to describe viscoelastic behaviors. The objectives of this study were to determine whether the FZ model can accurately describe the shear viscoelastic properties of NP tissue and determine if the fractional order (α) is related to tissue hydration. 30 caudal IVDs underwent equilibrium dialysis in 5% or 25% polyethylene glycol solutions to alter tissue hydration. Excised NP tissue underwent stress relaxation testing in shear and unconfined compression. Stress relaxation data was fitted to the FZ model to obtain viscoelastic properties. In both loading modes, the initial modulus was greater for the less hydrated 25% equilibrated samples compared to 5% with no change in the equilibrium modulus. Samples with lower water content (25% samples) had shorter relaxation times in shear and longer time constants in compression, highlighting the different interactions between the fluid and solid matrix in loading modes. Samples with lower water content had α values closer to 0, indicating that less hydrated samples behaved more solid-like on the viscoelastic spectrum. Tissue hydration correlated with α values for 25% samples in shear. This study demonstrates that the FZ model may be used to describe IVD tissue behavior under both loading modes; however, the greatest utility of the FZ model is in describing flow-independent shear behaviors, and α may inform tissue hydration in shear.