Influence of the Fixed Negative Charges on the Measured Poisson’s Ratio, Young’s Modulus and Electrical Response of Articular Cartilage

Under physiological conditions, the solid extracellular matrix (ECM) of articular cartilage derives negative charges from its proteoglycan content [1]. The load-deformation behavior of the tissue (i.e., its apparent mechanical property) comes from not only the intrinsic matrix properties, but also these charges that are attached to the matrix. Study shows that in 1D configurations (such as confined compression), at equilibrium, the osmotic pressure associated with these fixed charges may contribute as much as 50% of the apparent compressive modulus [1–3].