Figure 7.

Schematic illustration of the working hypothesis on the structural role of decorin in cartilage matrix. Decorin binds to aggrecan to increase its adhesion with other aggrecan molecules and with collagen II fibrils, thereby enhancing the assembly and structural integrity of the aggrecan network in cartilage ECM. In turn, the integrity of the aggrecan network is necessary for the GAG–GAG electrical double layer repulsion that determines the elastic load-bearing properties of cartilage (e.g., E_ind, E_L) and for the nanoscale solid−fluid interaction and fluid pressurization that endows the poroelastic energy dissipation properties of cartilage (e.g., E_H/E_L, δ_m, and k). In the schematics, the packing densities of collagen fibrils and aggrecan networks are reduced to increase clarity.