The patellar membrane is understood to be the cartilaginous surface of the patella, and once damaged the cartilaginous surface cannot be restored because cartilage does not regenerate. If the cartilaginous surface of the patella in the knee joint is degenerated and worn out, it can be treated with intra-articular injections of sodium vitrate or oral administration of glucosamine, which is a cartilage nutrient. If the cartilage surface is defective and the defect area is not large, arthroscopic microfracture can also be used to treat the defect. Through the exudation of blood from the surface of the bone, fibrocartilage can be formed locally, which can improve the function of the joint. If the defect is large, only cartilage transplantation can be performed.