Finite Element Modeling of Articular Cartilage to Characterize Biomechanical Properties: The Effect of Cartilage Surface Curvature

Abstract

Degeneration and loss of articular cartilage in the synovial joint have been recognized as the main source of osteoarthritis which leads to pain, swelling and limit the joint mobility. Extensive experimental and computational studies have been performed to study the mechanical behavior and characterize the biomechanical properties of articular cartilage. However, a lack of attention was made on the curvature of the cartilage surface by assuming it was a flat surface. This assumption was inappropriate since the synovial joints possessed curved geometrical shape and may contribute to inaccuracies in characterizing the articular cartilage biomechanical properties. This study aims to examine the effects of the curvature of the cartilage surface in finite element modeling which incorporated with the experiment method to characterize biomechanical properties of articular cartilage. In this study, the biomechanical behavior of contact pressure and pore pressure were investigated at different radius of cartilage surface using the finite element method. The cartilage biomechanical properties of elastic modulus and permeability of the bovine humeral head were then characterized using a combination of indentation test and finite element method. It was found that the cartilage curvature produced a 6% difference in contact pressure and a 39% difference in pore pressure distribution compared to the flat surface cartilage in finite element analysis. Furthermore, significant observation in the characterized biomechanical properties was obtained where the differences of the cartilage curvature reached 33% for elastic modulus and 56% for permeability. Based on the results, the surface curvature of articular cartilage could play an important role in the computational modeling and characterization of its biomechanical properties.