Trinity Centre for Bioengineering, School of Engineering, Trinity College Dublin, Dublin, Ireland.
Osteoarthritis Cartilage. 2012 Nov;20(11):1417-25. doi: 10.1016/j.joca.2012.08.005. Epub 2012 Aug 10.
The objective of this study was to elucidate the role of the superficial region of articular cartilage in determining the dynamic properties of the tissue. It is hypothesised that removal of the superficial region will influence both the flow dependent and independent properties of articular cartilage, leading to a reduction in the dynamic modulus of the tissue.
Osteochondral cores from the femoropatellar groove of three porcine knee joints were subjected to static and dynamic loading in confined or unconfined compression at increasing strain increments with and without their superficial regions. Equilibrium moduli and dynamic moduli were measured and the tissue permeability was estimated by fitting experimental data to a biphasic model.
Biochemical analysis confirmed a zonal gradient in the tissue composition and organisation. Histological and PLM analysis demonstrated intense collagen staining in the superficial region of the tissue with alignment of the collagen fibres parallel to the articular surface. Mechanical testing revealed that the superficial region is less stiff than the remainder of the tissue in compression, however removal of this region from intact cores was found to significantly reduce the dynamic modulus of the remaining tissue, suggesting decreased fluid load support within the tissue during transient loading upon removal of the superficial region. Data fits to a biphasic model predict a significantly lower permeability in the superficial region compared to the remainder of the tissue.
It is postulated that the observed decrease in the dynamic moduli is due at least in part to the superficial region acting as a low permeability barrier, where its removal decreases the tissue's ability to maintain fluid load support. This result emphasises the impact that degeneration of the superficial region has on the functionality of the remaining tissue.
本研究旨在阐明关节软骨表面区域在决定组织动态特性方面的作用。假设去除表面区域将影响关节软骨的流动相关和不相关特性，导致组织动态模量降低。
来自三个猪膝关节股骨髌沟的骨软骨核心在有和没有其表面区域的情况下，在受限或不受限的压缩下，以递增的应变增量进行静态和动态加载。测量平衡模量和动态模量，并通过将实验数据拟合到双相模型来估计组织渗透性。
生化分析证实了组织成分和组织排列的分区梯度。组织学和 PLM 分析表明，组织的表面区域有强烈的胶原染色，胶原纤维与关节表面平行排列。机械测试表明，在压缩中，表面区域比组织的其余部分柔软，但从完整核心中去除该区域发现显著降低了剩余组织的动态模量，表明在去除表面区域时，组织内的流体负荷支持减少。双相模型拟合数据预测表面区域的渗透性明显低于组织的其余部分。
据推测，观察到的动态模量降低至少部分归因于表面区域作为低渗透性屏障的作用，其去除降低了组织维持流体负荷支持的能力。这一结果强调了表面区域退化对剩余组织功能的影响。
