Cartilage degradation and associated changes in biomechanical and electromechanical properties

Abstract

In osteoarthritis (OA), the combination of altered cartilage matrix composition and mechanical wear from joint motion can result in erosion of cartilage down to the bone surface [1]. In its degenerated state, OA cartilage exhibits dramatically different biochemical, physicochemical, mechanical, and electromechanical properties from normal tissue, including a distinct loss of proteoglycan [2,3], marked collagen network fibrillation [4], increases in tissue hydration [5], and loss of compressive stiffness [6]. The role of enzymatic degradation in OA has been studied extensively, but is not completely understood. It has been suggested [7] that families of enzymes, including matrix metalloproteinases (MMPs) [8,9], serine proteinases [10], and a novel “aggrecanase” [11] contribute to cartilage degradation in OA. It seems likely that the enzymatic component of OA involves a cascade of activities which work in tandem to degrade the tissue.