Cartilage damage can be recovered within a certain range. Cartilage damage can usually be divided into several types. Mild cartilage damage can be repaired by itself, while auxiliary nutritional cartilage drugs, such as chondroitin sulfate, can accelerate cartilage repair. If subchondral bone leakage occurs, cartilage damage within 1cm^2 can be repaired on its own, or local microfracture surgery can be performed to promote cartilage repair. However, if the area of injury exceeds 1 cm^2, it is difficult to repair. Because the cartilage repair ability is poor and the area is too large for the cartilage to repair itself, even if microfracture surgery is used, the healing effect will not be achieved. Usually, attention should be paid to protect the articular cartilage to avoid cartilage damage.