A composites theory predicts the dependence of stiffness of cartilage culture tissue on collagen volume fraction
by
N.K. Simha, M. Fedewa, P.H. Leo, J.L. Lewis and T.R. Oegema
in
Journal of Biomechanics, 32, pp. 503- 509, 1999.
Category: Journal Article
Keywords: Articular cartilage; Theoretical composites model; Osteoarthritis; Cartilage modulus; Culture tissue
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Abstract:
The tensile sti¤ness of tissue grown from chondrocyte culture was both measured experimentally and predicted using a composites model theory relating tissue microstructure to macroscopic material sti¤ness. The tissue was altered by several treatment protocols to provide a wide range of collagen Þbril volume fraction (0.015Ð0.15). The rate of change of tissue modulus with change in collegen volume fraction predicted by the theory was within 14% of the slope of the linear Þt through the experimental data, without the use of Þtting parameters for the theoretical value of the slope. Use of the model to simulate cytokine mediated tissue digestion suggests that the action of IL-1b and retinoic acid is mainly removal of proteoglycans and some removal of collagen. The model also indicates that the matrix and collagen remaining in the tissue has the same elastic properties as the untreated tissue, and is not damaged due to the alteration. YoungÕs modulus of the collagen Þbrils is predicted to be 120 MPa, a value in the range of previous studies. This value is dependent mainly on the matrix modulus and collagen Þbril volume fraction and not on PoissonÕs ratio of either matrix or Þbril. PoissonÕs ratio of the tissue depends primarily on the PoissonÕs ratio of the matrix.
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