The main points of postoperative rehabilitation exercises are as follows: 1. ankle pump exercise and quadriceps contraction exercise; 2. the use of the machine (necessary); 3. no weight-bearing on the affected limbs for 6 weeks after surgery (important). Ankle pump exercise: with the patient lying in bed with both lower limbs straightened, both ankles naturally relaxed to do dorsiflexion, dorsiflexion to the maximum and dorsiflexion to the maximum at the same time Quadriceps contraction and relaxation exercise: with the patient lying in bed with both legs naturally straightened, repeatedly perform the activity of contracting the thigh muscles of both lower limbs for 5 seconds, then relaxing for 2 seconds. I. In the first week, light functional exercise was performed. The isometric contraction of the quadriceps muscle and the extension and flexion of the ankle and toe joints were started at 24 hours after surgery. Continuous passive mobility device functional exercise was started at 10 hours postoperatively. Second, in the second week, the rehabilitation focused on restoring the range of motion of the knee joint. It is possible to walk on the ground with the aid of crutches, but no weight-bearing is allowed on the affected limb. Premature weight-bearing may cause new damage within the knee joint. Third, for 3 to 4 weeks, more vigorous exercise is encouraged so that the muscle tone and range of motion of the affected limb are completely restored to normal. Gradually perform mobility training within the normal range of the knee joint; at the same time, strengthen the straight leg raising training and quadriceps resistance isometric contraction exercise of the affected limb to enable the patient to resume normal activities. Fourth, in the second month, further comprehensive functional rehabilitation training will be conducted to promote the complete restoration of normal activity of the affected limb. Gradually increase the ankle resistance of quadriceps resistance exercise and start normal physical exercise. Such as cycling, swimming or running, etc. However, avoid strenuous physical activities. It takes about 4 to 6 months to achieve full recovery.