Grade I, softening of the cartilage
; Grade II, fissures; Grade III, partial thickness loss of cartilage
; Grade IV, exposure of subchondral bone.
The problem with hyaline cartilage, which is what covers the bones inside of joints, is that it cannot regenerate itself. It has limited repair capabilities. If it does repair a small portion of the articular cartilage, it is with fibrocartilage. Fibrocartilage is sort of a scar for cartilage.