Mechanics of Collagen Fiber Network and Fluid Pressurization in Articular Cartilage of Knee Joint

Introduction The load response of a knee joint is dominated by the mechanical properties of articular cartilage, which consists of proteoglycan matrix, collagen fiber network and a fluid. The interplay of these three constituents determines the load support of articular cartilage in the joint. Finite element analysis has been widely applied to study joint mechanics. Accurate knee contact geometries are used in recent modeling with huge amount of computations [1,2], even when articular cartilage is generally simplified as one phase isotropic elastic material. Such simplified approaches can be used to simulate either the static or instantaneous response of the joint, when fluid flow is absent. The experimentally observed influences of fluid flow and site-specific collagen orientations have not been reported in computer knee modeling. The objective of the present study was to determine the influence of collagen network on the deformation and fluid flow in knee cartilage. The real joint geometry, true tissue thickness variations and actual fiber orientations were incorporated in the finite element model.