Poromechanical Modeling of Porcine Knee Joint Considering Site-Dependent Material Properties of Articular Cartilage from Indentation Testing
Date
2020-06-01
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Abstract
Articular cartilage mechanical properties can be ascribed to the variations of morphology and concentration of its constituents across the tissue. The knowledge of site-specific properties of articular cartilage of knee joints may be important for understanding the onset of cartilage degeneration in the knee. Few earlier studies have focused on the poromechanical response of knee joints with site-specific material properties across cartilage. Animal knee joints are often used to study the mechanical properties of soft tissues and validate a computational model of the knee joint and aim to translate the findings to human knee joint biomechanics. On that account, the objectives of this study were to explore the variations of cartilage mechanical properties across the tissue and evaluate the effect of site-specific mechanical properties of cartilage on the poromechanical response of a porcine knee joint model. Fresh porcine knee joints were used in the present study to extract cartilage properties and reconstruct a knee geometry using magnetic resonance imaging. The automated indentation testing with the Mach-1 tester was used to determine the site-dependent cartilage properties. A displacement input was applied to sampling points followed by a partial relaxation. The thickness mapping of the sampling points followed the indentation testing to collect all required data. The two-way ANOVA was performed on the measurement data and demonstrated the dependence of the cartilage thickness and reaction force on sampling regions. Further analyses of the indentation data showed that the variations of the recorded reaction forces were not solely due to the cartilage thickness. To reduce the effort of curve-fitting the material model parameters to various site-specific indentation data, the surface of articular cartilage was divided into 14 regions to obtain the region-dependent material properties. The non-fibrillar matrix and fibrillar network of femoral and tibial cartilages had various stiffnesses across the tissue as obtained from the fitting procedure. In the simulated knee joint, the force-compression relationship of the whole knee joint was determined by both the compression magnitude and the compression rate. By applying the region-dependent properties to finite element simulations of the porcine knee joint, the stress, fluid pressure, and contact pressure magnitudes and distributions of the cartilage were altered. The results indicated that the realistic implementation of region-dependent properties of tissues may be necessary for understanding the load distribution in the joint.
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Zare, M. (2020). Poromechanical Modeling of Porcine Knee Joint Considering Site-Dependent Material Properties of Articular Cartilage from Indentation Testing (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.