Depth-dependent confined compression modulus of full-thickness bovine articular cartilage
Depth-dependent confined compression modulus of full-thickness bovine articular cartilage
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DOI：
10.1002/jor.1100150404
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发表时间：
1997-07-01
影响因子：
2.8
通讯作者：
Sah, RL
中科院分区：
文献类型：
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作者：
Schinagl, RM;Gurskis, D;Sah, RL
本研究的目的是确定牛关节软骨的平衡限制压缩模量，因为它随距关节表面的深度而变化。骨软骨样品被压缩软骨厚度的8%、16%、24%和32%并允许t1平衡。使用荧光标记的软骨细胞核作为内在的基准标记来测量软骨内的组织内位移。然后计算包括表面1.125μm的九个连续的125μm厚的软骨层和邻近软骨-骨界面的250μm厚的软骨层中的轴向应变。相邻的骨软骨芯也进行了有限压缩测试，以确定实现相同压缩水平所需的平衡应力。将每个样品的每一层的应力-应变数据拟合到有限变形应力-应变关系，以确定每个组织层中的平衡限制压缩模量。压缩模量随着距关节表面的深度显着增加，范围从浅层的 0.079 +/- 0.039 MPa 到第九层的 1.14 +/- 0.44 MPa。最深层的厚度为250微米，模量为2.10+/-2.69兆帕。这些模量与全层软骨的表观“均匀”模量 (0.38 +/- 0.12. MPa) 明显不同，范围为该值的 21% 至 560%。相对较低的模量和压缩引起的表层硬化表明这些层极大地影响软骨的生物力学行为，例如在有限压缩测试期间。深度依赖模量的描述为详细研究软骨的组成、结构和功能在老化、修复和退化等过程中的关系提供了基础。
The objective of this study was to determine the equilibrium confined compression modulus of bovine articular cartilage as it varies with depth from the articular surface. Osteochondral samples were compressed by 8, 16, 24, and 32% of the cartilage thickness and allowed tl, equilibrate. Intratissue displacement within the cartilage was measured with use of fluorescently labeled chondrocyte nuclei as intrinsic, fiducial markers. Axial strain was then calculated in nine sequential 125 mu m thick cartilage layers comprising the superficial 1.125 mu m and in a 250 mu m thick layer of cartilage adjacent to the cartilage-bone interface. Adjacent osteochondral cores were also tested in confined compression to determine the equilibrium stresses required to achieve the same levels of compression. Stress-strain data for each layer of each sample were fit to a finite deformation stress-strain relation to determine the equilibrium confined compression modulus in each tissue layer. The compressive modulus increased significantly with depth from the articular-surface and ranged from 0.079 +/- 0.039 MPa in the superficial layer to 1.14 +/- 0.44 MPa in the :ninth layer. The deepest layer, 250 mu m thick, had a modulus of 2.10 +/- 2.69 MPa. These moduli were markedly different from the apparent ''homogeneous'' modulus for full-thickness cartilage (0.38 +/- 0.12. MPa) and ranged from 21 to 560% of that value. The relatively low moduli and the compression induced stiffening of the superficial layers suggest that these layers greatly affect the biomechanical behavior of cartilage, such as during confined compression testing. The delineation of the depth-dependent modulus provides a basis for detailed study of the relationship between the composition, structure, and function of cartilage in such processes as aging, repair, and degeneration.