Cartilage damage is often classified into different grades based on the severity of the damage. A commonly used classification is the International Cartilage Repair Society (ICRS) classification:
-Grade I: soft site with less resistance than the surrounding, healthy cartilage.
-Grade II: superficial cracks or defects in the cartilage surface, less than half the total thickness.
-Grade III: deep cracks or fissures in the cartilage surface, more than half the total thickness.
-Grade IV: tear to the subchondral bone, affecting the total thickness of the cartilage surface.
-Grade V: impairment of the total thickness of the cartilage surface with involvement of the subchondral bone ('full-thickness defect').