Experimental and Biphasic FEM Determinations of the Material Properties and Hydraulic Permeability of the Meniscus in Tension¹

Tensile tests and biphasic finite element modeling were used to determine a set of transversely isotropic properties for the meniscus, including the hydraulic permeability coefficients and solid matrix properties. Stress-relaxation tests were conducted on planar samples of canine meniscus samples of different orientations, and the solid matrix properties were determined from equilibrium data. A 3-D linear biphasic and tranversely isotropic finite element model was developed to model the stress-relaxation behavior of the samples in tension, and optimization was used to determine the permeability coefficients, $k1$ and $k2,$ governing fluid flow parallel and perpendicular to the collagen fibers, respectively. The collagen fibrillar orientation was observed to have an effect on the Young’s moduli $(E1=67.8MPa,$$E2=11.1MPa)$ and Poisson’s ratios $(ν12=2.13,$$ν21=1.50,$$ν23=1.02).$ However, a significant effect of anisotropy on permeability was not detected $(k1=0.09×10−16m4/Ns,$$k2=0.10×10−16m4/Ns).$ The low permeability values determined in this study provide insight into the extent of fluid pressurization in the meniscus and will impact modeling predictions of load support in the meniscus.