I. Rehabilitation exercise plan at discharge The patient sits on the bedside, actively flexes and extends the lower leg or sits on the bed with a pillow under the knee joint to make the knee joint flex and then straighten, and practice more every day. At the same time with the whole body joint exercises, such as walking, walking up and down the stairs, etc.. In this way, not only the knee joint can be exercised, but also the whole body can be exercised to enhance physical fitness. Avoid strenuous movements during training, do not do jumping and sharp turning movements to prevent joint injuries. Second, dietary guidance Provide a high-protein, high-sugar diet. In addition to protein, it is necessary to supply enough carbohydrates to participate in protein endogenous metabolism, which can reduce wound edema and prevent infection. Supply collagen-rich pig skin or pig’s feet food, which can provide exogenous protein for patients to synthesize collagen fiber and proteoglycan, and also obtain a large amount of zinc and glycine and proline. Supply foods rich in copper: lean meat, liver, aquatic products, shrimp, etc. Supply foods rich in multivitamins and minerals. The patient should walk more times a day, followed by gradually increasing the distance walked. Patients should use crutches or a walking frame to protect the knee joint when walking, and should pay attention to turn around by walking in small steps to avoid twisting the knee joint. Choose a firm, straight-backed chair with armrests at home, which facilitates the patient to stand up or sit down, not to sit on a low soft sofa or recliner. When bathing at home, avoid slipping and falling, avoid catching a cold, and follow the principle of treating minor illnesses to prevent distant infection of the replacement joint. IV. Go to the hospital for examination when there are the following symptoms 1. increased pain in the knee joint; 2. pain or swelling in the calf or thigh; 3. abnormal redness, heat or pus at the incision site; 4. difficulty in breathing or chest pain; 5. fever over 38℃.