Mizrahi J, Maroudas A, Lanir Y, Ziv I, Webber T J
Biorheology. 1986;23(4):311-30. doi: 10.3233/bir-1986-23402.
The present study was undertaken with two objectives in view. The first was to distinguish between the "instantaneous" deformation and creep of articular cartilage when subjected to a step loading in unconfined compression. This was done by observing changes in the specimen's diameter rather than its thickness. The second objective was to investigate experimentally the anisotropic behaviour of cartilage in a compressive loading mode, corresponding to the physiological situation. An apparatus was thus developed and constructed which enabled us to follow the "instantaneous" changes of the surface area of the sample as the latter was being loaded in unconfined compression. Specimens of human articular cartilage from normal femoral heads and condyles were tested. Full thickness specimens were tested with and without the underlying bone, as well as partial thickness specimens, characterizing the different zones of cartilage. Solutions of different ionic strength were used to vary the osmotic stress and specimens covering a considerable range of proteoglycan concentrations were selected. The effects of hydration and proteoglycan removal on the "instantaneous" deformation were also studied. The "instantaneous" deformation was found to be of a strongly anisotropic nature in all zones. The deformation was always smaller along the Indian-ink prick pattern than at 90 degrees to it, and this effect was most pronounced in the superficial zone of cartilage. The results reveal an analogy with the tensile properties of cartilage and indicate that the collagen network is mainly responsible for controlling the "instantaneous" deformation. The proteoglycans play an indirect role by modulating the stiffness of the collagen network through their osmotic pressure.
本研究有两个目的。第一个目的是区分关节软骨在无侧限压缩下承受阶跃载荷时的“瞬时”变形和蠕变。这是通过观察样本直径而非厚度的变化来实现的。第二个目的是通过实验研究软骨在压缩载荷模式下的各向异性行为，这与生理情况相对应。因此开发并构建了一种仪器，使我们能够在样本进行无侧限压缩加载时跟踪其表面积的“瞬时”变化。对来自正常股骨头和髁的人体关节软骨样本进行了测试。对全层样本在有和没有下层骨的情况下进行了测试，以及部分厚度样本，以表征软骨的不同区域。使用不同离子强度的溶液来改变渗透压，并选择了覆盖相当大范围蛋白聚糖浓度的样本。还研究了水合作用和蛋白聚糖去除对“瞬时”变形的影响。发现“瞬时”变形在所有区域都具有强烈的各向异性。沿着印度墨水刺痕图案方向的变形总是小于与之成90度方向的变形，并且这种效应在软骨的表层最为明显。结果揭示了与软骨拉伸特性的相似性，并表明胶原网络主要负责控制“瞬时”变形。蛋白聚糖通过其渗透压调节胶原网络的刚度而发挥间接作用。
