Early stage: (1 day-1 month after surgery) 1. On the day of surgery: start moderate isometric contraction of quadriceps muscle, ankle plantarflexion and dorsiflexion, and straight-leg elevation training right after anesthesia. Ankle plantarflexion and dorsiflexion exercises were performed 15 times/hour. 2.Postoperative day 2: 15 degrees, 30 degrees of knee flexion quadriceps multi-point isometric static contraction can be added. And can support the crutches, the affected limb 1/4 weight-bearing. Walking weight-bearing time of 5 minutes each time, not longer than 20 minutes a day. 3, postoperative days 3-7: quadriceps contraction can reach 100-500 times / day. Use skateboard or wall sliding to train joint mobility. Begin patellar lift training, knee press training. Rehabilitation bicycle (stationary bicycle) training can be added. If the joint is swollen and painful, use ultrasound, cold therapy and other auxiliary treatment. 4.Post-operative week 2: Flexion of the knee should reach 90 degrees. The number of straight leg raising and muscle contraction and relaxation should be more than 1000 times/day. Weight-bearing can reach 1/2 body weight, and the total time of weight-bearing walking is no more than 20 minutes per day. Arthroscopic incisions can be removed. Perform quadriceps instrumentation and proprioceptive training. 5.Postoperative week 3: weight-bearing to reach 3/4 body weight, knee flexion to the preoperative angle, increase the amount of lower limb activity. Strengthen the quadriceps function training, increase the micro-squat standing training to smoothly over to the fully correct walking. The total daily walking time should be limited to 30 minutes in the first three weeks after surgery. 6. Postoperative week 4: Full weight bearing, increase isometric contraction of quadriceps, straight leg raising and micro squatting. The daily walking time is increased moderately according to the recovery situation. The maximum distance can be walked once a week, and the daily walking is limited to half distance, controlling the amount of walking load. Intermediate stage: (1 month-2 months after surgery) Participate in work or daily household chores, and control the distance of walking load. Post-operative period: (2-3 months after surgery) Gradually return to normal activities. If the affected knee is still swollen and uncomfortable, the amount of daily exercise should be controlled. Resumption of exercise: (3 months after surgery) Form the habit of daily rehabilitation training, advocate the concept of “cherishing joints, lifelong rehabilitation”, and avoid excessive squatting and mountain climbing. Take 1-2 courses of glucosamine orally every year (1-3 months each time) and take calcium supplements to prevent osteoporosis.