Surgery is necessary to remove the free body of the knee joint as soon as possible to reduce damage to the soft tissue or cartilage in the knee joint. Once the cartilage is damaged, it is irreversible and there is no way to repair and regenerate the cartilage. If the cartilage is not present, the knee joint will become painful under weight bearing activities, as in the case of the knee joint. If the free body is not removed, the cartilage around the knee joint will be damaged or worn away, causing severe pain when walking and the bones of the knee joint touching the bones. In addition, the free body of the knee joint may get stuck in the joint cavity and cause sudden changes in the joint, such as being afraid to move and severe pain. Therefore, free bodies in the knee joint can do more harm than good and should be removed.