It has been almost a month since the knee implantation surgery, and the knee effusion is swollen up, which may be caused by traumatic stress reaction, synovitis, joint infection, etc. According to the cause of the disease, we can choose to reduce weight bearing, physical therapy, anti-infection treatment or surgical treatment to relieve and treat. 1. Traumatic stress reaction: due to the implantation of artificial prosthesis, it can lead to traumatic stress reaction in local tissues and joint effusion, which should be rested in bed, reduce the weight of the affected limbs, elevate the affected limbs, and apply hot compresses locally in order to reduce the production of effusion. 2. Synovitis: synovitis is generally manifested as joint effusion, swelling, localized fever, etc. Patients should pay attention to rest, avoid excessive walking, can be appropriate with hot compresses, acupuncture, ultrashort wave and other physical therapy, to promote self-absorption of effusion, and gradually improve. 3. Joint infection: if accompanied by redness of the skin, skin temperature rise, and hematological inflammation indicators significantly higher, severe pain, we need to consider the infection caused by the need for anti-infection treatment, while puncture culture, but also need to incise and drain, or even surgical treatment. Knee transplant surgery almost a month ago, knee effusion swelling up a good big, need to patients timely to the hospital, clear cause, according to the cause and then targeted treatment.