Role of load history in intervertebral disc mechanics and intradiscal pressure generation
Role of load history in intervertebral disc mechanics and intradiscal pressure generation
复制标题
DOI：
10.1007/s10237-011-0295-1
复制
发表时间：
2012-01-01
影响因子：
3.5
通讯作者：
Hsieh, Adam H.
中科院分区：
文献类型：
--
作者：
Hwang, David;Gabai, Adam S.;Hsieh, Adam H.
固-流相互作用在介导生物组织的粘弹性行为中起着重要作用。在椎间盘中，含水量受许多因素影响，包括年龄、疾病和机械负荷，导致刚度特性的变化。我们假设分区应力分布取决于载荷历史，或盘所经历的先前应力。为了研究这些影响，使用由两个阶段组成的方案对大鼠尾侧运动节段进行体外压缩蠕变生物力学测试：预应力阶段（变化以代表不同的载荷历史），随后立即进行所有预应力组均相同的制动阶段。三个分析模型被用来拟合实验数据，以评估总的和分区光盘力学的负载历史的影响。模型结果表明，虽然总的瞬态响应是不敏感的负载历史，可能会有变化的内部力学的光盘。特别是，一个流体传输模型表明，髓核的作用，在抵抗蠕变在prestress依赖于预应力条件。使用类似定义的负荷历史方案进行单独的实验，以验证这些预测通过测量椎间盘内压力与光纤传感器。我们发现，椎间盘内压力产生的能力是负载历史依赖性的，并表现出更大的灵敏度比预测的分析模型。在0.5MPa的剪切载荷作用下，低预应力下的IDP为537.2kPa，而高预应力下的IDP为373.7kPa。基于这些测量结果，我们开发了一个简单的模型，可以描述髓核中的压力-剪切环境。这些发现可能对我们理解机械应力如何促进椎间盘健康和疾病病因学具有重要意义。
Solid-fluid interactions play an important role in mediating viscoelastic behaviour of biological tissues. In the intervertebral disc, water content is governed by a number of factors, including age, disease and mechanical loads, leading to changes in stiffness characteristics. We hypothesized that zonal stress distributions depend on load history, or the prior stresses experienced by the disc. To investigate these effects, rat caudal motion segments were subjected to compressive creep biomechanical testing in vitro using a protocol that consisted of two phases: a Prestress Phase (varied to represent different histories of load) followed immediately by an Exertion Phase, identical across all Prestress groups. Three analytical models were used to fit the experimental data in order to evaluate load history effects on gross and zonal disc mechanics. Model results indicated that while gross transient response was insensitive to load history, there may be changes in the internal mechanics of the disc. In particular, a fluid transport model suggested that the role of the nucleus pulposus in resisting creep during Exertion depended on Prestress conditions. Separate experiments using similarly defined load history regimens were performed to verify these predictions by measuring intradiscal pressure with a fibre optic sensor. We found that the ability for intradiscal pressure generation was load history-dependent and exhibited even greater sensitivity than predicted by analytical models. A 0.5 MPa Exertion load resulted in 537.2 kPa IDP for lowmagnitude Prestress compared with 373.7 kPa for high magnitude Prestress. Based on these measurements, we developed a simple model that may describe the pressure-shear environment in the nucleus pulposus. These findings may have important implications on our understanding of how mechanical stress contributes to disc health and disease etiology.