ABSTRACT
Articular cartilage is essential for normal diarthrodial joint function.[2] Existing as the contact surface of joints, articular cartilage functions to transfer and effectively lessen loads from one subchondral bone to another. Articular cartilage and synovial fluid combine to form a wear-resistant and friction-reduced surface that is only a few millimeters thick. This solid-fluid nature of cartilage creates a mechanoprotective environment that is favorable for the tissue’s exceptional durability.[3]
Unlike most tissues, cartilage is avascular, aneural, and alymphatic and contains a sparse number of cells (chondrocytes) that are encased in an extracellullar matrix (ECM). In articular cartilage chondrocytes constitute approximately 10% of the total volume.[4]
Articular cartilage is often considered a fiber-reinforced gel containing a fluid phase of primarily water that makes up 75-80% of the wet weight of cartilage.[4] The remaining solid phase contains approximately 50% collagen, 30-35% proteoglycans and 15-20% glycoproteins by dry weight of tissue.[5] These assembled macromolecules are responsible for the matrix architecture and give articular cartilage its inherent structure and properties.
