High-frequency ultrasound is used in this study to measure noninvasively, by means of osmotic loading, changes in speed of sound and cartilage thickness caused by variations of the salt concentration in the external bath. Articular cartilage comprises three main structural components: Water, collagen fibrils and proteoglycan macromolecules carrying negative charges. The negatively charged groups of proteoglycans attract cations and water into tissue and govern its shrinkage/swelling behavior, which is a fundamental mechano-electrochemical function of cartilage tissue. In this study, the mechano-electrochemical behavior of cartilage is modeled by a diffusion model. The proposed model enables simulations of cartilage osmotic loading under various parameter settings and allows to quantify cartilage mechanical properties. This theoretical model is derived from the kinetic theory of diffusion. The objectives of the study are to quantify time dependent changes in cartilage thickness, and in speed of sound within tissue with help of the finite element based simulations and data from experiments. Experimental data are obtained from fresh and trypsinized ovine patella samples. Results show that the proposed diffusion model is capable to describe transient osmotic loading of cartilage. Mean values and their deviations of the relative changes of cartilage characteristics in response to chemical loading are presented.

中文翻译：

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高频超声评估渗透负荷下软骨的瞬时变化

在这项研究中，使用高频超声波通过渗透负荷无创地测量由外部浴中盐浓度的变化引起的声音速度和软骨厚度的变化。关节软骨包括三个主要结构成分：水，胶原纤维和带负电荷的蛋白聚糖大分子。蛋白聚糖带负电荷的基团将阳离子和水吸引到组织中，并控制其收缩/膨胀行为，这是软骨组织的基本机械电化学功能。在这项研究中，通过扩散模型对软骨的机械电化学行为进行建模。提出的模型可以模拟各种参数设置下的软骨渗透负荷，并可以量化软骨的力学性能。该理论模型源自扩散的动力学理论。该研究的目的是借助基于有限元的模拟和实验数据来量化软骨厚度以及组织内声音速度随时间的变化。实验数据是从新鲜的和经胰蛋白酶消化的绵羊骨样品中获得的。结果表明，所提出的扩散模型能够描述软骨的瞬时渗透负荷。给出了响应于化学负载的软骨特性相对变化的平均值及其偏差。实验数据是从新鲜的和经胰蛋白酶消化的绵羊骨样品中获得的。结果表明，所提出的扩散模型能够描述软骨的瞬时渗透负荷。给出了响应于化学负荷的软骨特性的相对变化的平均值及其偏差。实验数据是从新鲜的和经胰蛋白酶消化的绵羊骨样品中获得的。结果表明，所提出的扩散模型能够描述软骨的瞬时渗透负荷。给出了响应于化学负荷的软骨特性的相对变化的平均值及其偏差。