Routine procedure of joint cavity injection: 1. disinfection: conventional 2% iodine, 75% alcohol (deiodination) three times skin disinfection 2. find the puncture point, pierce the needle (avoid the main blood vessels, nerves) 3. draw back (when there is fluid in the joint must first draw out the fluid) 4. retain the needle, change the syringe to inject sodium vitrate 5. after the injection of spelt, use sterile cotton to press the needle mouth, pull out the needle and cover with sterile gauze or hemostatic patch 6. After injection, move the knee joint several times to evenly distribute the drug in the joint cavity Precautions for joint cavity injection: 1, allergy, damage, infection, etc. should not be injected 2, do not inject synovial membrane, ligaments and fat 3, do not puncture too deep to damage the articular cartilage 4, try to achieve a successful outcome Adverse reactions: pain, swelling, rash, itching and other symptoms may appear at the injection site in individual patients, generally 2-3 days. -If the symptoms do not subside, the medication should be stopped and the necessary treatment should be carried out.