Faculty Publications
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Item Investigation on the Influence of Soft Tissues in Knee Joint on Load Transfer Mechanism during the Gait Cycle(American Institute of Physics, 2024) Raju, V.; Koorata, P.K.Soft tissues keep the human knee joint stable and serve an essential function in limiting motion during daily activities.The goal of this work is to investigate the influence of knee components during a person subjected to walking. A 3D finite element model of a knee joint used for the analysis. The knee kinetics (forces and rotation) during the stance phase of a gait in all degrees of freedom are incorporated into the model. The contact pressure, effective Lagrange strain, maximum shear stress, effective stress and total displacement generated on all the soft tissues are compared. The meniscus shows a more excellent value in all areas concerning other tissues, and for stress values, it is 4 to 5 times greater. The result also indicates that the contact pressure of the tibial cartilage is higher than the femur cartilage throughout the cycle. However, the effective Lagrange strain of femur cartilage is higher than tibial cartilage during the initial phase of the cycle and later declined. These values might help develop comprehensive computational tools to help us better understand the knee injury and disease causes. © 2024 American Institute of Physics Inc.. All rights reserved.Item Influence of material heterogeneity on the mechanical response of articulated cartilages in a knee joint(SAGE Publications Ltd, 2022) Raju, V.; Koorata, P.K.Structurally, the articular cartilages are heterogeneous owing to nonuniform distribution and orientation of its constituents. The oversimplification of this soft tissue as a homogeneous material is generally considered in the simulation domain to estimate contact pressure along with other physical responses. Hence, there is a need for investigating knee cartilages for their actual response to external stimuli. In this article, impact of material and geometrical heterogeneity of the cartilage is resolved using well known material models. The findings are compared with conventional homogeneous models. The results indicate vital differences in contact pressure distribution and tissue deformation. Further, this study paves way for standardizing material models to extract maximum information possible for investigating knee mechanics with variable geometry and case specific parameters. © IMechE 2022.Item Computational assessment on the impact of collagen fiber orientation in cartilages on healthy and arthritic knee kinetics/kinematics(Elsevier Ltd, 2023) Raju, V.; Koorata, P.K.Background: The inhomogeneous distribution of collagen fiber in cartilage can substantially influence the knee kinematics. This becomes vital for understanding the mechanical response of soft tissues, and cartilage deterioration including osteoarthritis (OA). Though the conventional computational models consider geometrical heterogeneity along with fiber reinforcements in the cartilage model as material heterogeneity, the influence of fiber orientation on knee kinetics and kinematics is not fully explored. This work examines how the collagen fiber orientation in the cartilage affects the healthy (intact knee) and arthritic knee response over multiple gait activities like running and walking. Methods: A 3D finite element knee joint model is used to compute the articular cartilage response during the gait cycle. A fiber-reinforced porous hyper elastic (FRPHE) material is used to model the soft tissue. A split-line pattern is used to implement the fiber orientation in femoral and tibial cartilage. Four distinct intact cartilage models and three OA models are simulated to assess the impact of the orientation of collagen fibers in a depth wise direction. The cartilage models with fibers oriented in parallel, perpendicular, and inclined to the articular surface are investigated for multiple knee kinematics and kinetics. Findings: The comparison of models with fiber orientation parallel to articulating surface for walking and running gait has the highest elastic stress and fluid pressure compared with inclined and perpendicular fiber-oriented models. Also, the maximum contact pressure is observed to be higher in the case of intact models during the walking cycle than for OA models. In contrast, the maximum contact pressure is higher during running in OA models than in intact models. Additionally, parallel-oriented models produce higher maximum stresses and fluid pressure for walking and running gait than proximal-distal-oriented models. Interestingly, during the walking cycle, the maximum contact pressure with intact models is approximately three times higher than on OA models. In contrast, the OA models exhibit higher contact pressure during the running cycle. Interpretation: Overall, the study indicates that collagen orientation is crucial for tissue responsiveness. This investigation provides insights into the development of tailored implants. © 2023 IPEM