Evidence brief
Articular Cartilage Structure and Function
Type II collagen provides tensile strength
Proteoglycans (aggrecan) provide compressive resistance
Water content 70-80% critical for function
Four zones: superficial, transitional, deep, calcified
Biphasic mechanical behavior
Cartilage structure determines its unique mechanical properties and explains why damage is difficult to repair.
Know the zones and their collagen orientation. Superficial zone: tangential fibers, wear resistance. Deep zone: perpendicular fibers, load transmission. Proteoglycans attract water (osmotic swelling). Explain why cartilage can't heal: avascular, limited progenitor cells. Chondrocyte vs matrix volume ratio.
Mow VC, Ratcliffe A, Poole AR. Cartilage and diarthrodial joints as paradigms for hierarchical materials and structures. Biomaterials. 1992;13(2):67-97.
Level V
Expert opinion or mechanism-based reasoning