Knee stiffness can be treated by several methods, such as repetitive joint flexion and extension activities, minimally invasive arthroscopic surgery, and artificial knee surface replacement surgery, as follows: I. Repetitive joint flexion and extension activities: If the knee stiffness is short-term, such as short-term joint stiffness caused by osteoarthritis of the knee, rheumatoid joint, or rheumatoid arthritis, repetitive joint flexion and extension activities can be used to speed up the recovery of the knee joint. It should also be treated for the primary disease with oral celecoxib, loxoprofen sodium, and adjunctive ultrashort wave therapy. Minimally invasive arthroscopic surgery: If the knee joint is stiff for a long time, minimally invasive arthroscopic surgery should be considered to release the joint and restore the range of motion of the joint, with postoperative muscle and joint rehabilitation training. Artificial knee surface replacement surgery: If there is joint deformity, artificial knee surface replacement surgery can also be considered, and post-operative rehabilitation can be used to restore joint flexibility, remove joint pain and improve joint deformity. Through the above active treatment, the symptoms of knee stiffness can be significantly improved.