Collagen-collagen versus collagen-proteoglycan interactions in the determination of cartilage strength

For articular cartilage to function as a stress-reducing layer in the joint, it must both deform to an appropriate level to achieve load-spreading as well as remain structurally coherent. Combined micromechanical and enzymatic studies of cartilage have demonstrated that the bulk of the extractable proteoglycans, while essential to the maintenance of compressive stiffness, contribute little to its cohesive strength. The study reported here clarifies fundamental aspects of the relationship between matrix components and the biomechanical function of cartilage.