Arthroscopic technology is the most advocated minimally invasive surgical method for the treatment of knee injuries, which has the advantages of intuition, precision, small trauma, and quick recovery, etc. Our department was the first to carry out arthroscopic surgery in the province in 2000 and has treated more than 2000 patients. The posterior cruciate ligament has the important function of stabilizing the joint, preventing the tibia from moving backward, and limiting the hyperextension and hyperflexion of the knee joint, and if the injury is not treated, it will lead to serious consequences such as meniscal damage, cartilage wear, and joint degeneration. For surgical treatment of complete posterior cruciate ligament injury, arthroscopic ligament reconstruction is preferred. Early postoperative rehabilitation exercises can improve and increase local blood circulation, increase muscle strength, prevent tendon and joint capsule adhesions, promote ligament shaping and regeneration, and maximize restoration of joint function. Please carry out the exercises under the guidance of our medical and nursing staff. If there is any discomfort during the exercise process, please consult with the doctor in charge or return to the hospital for review. (1) Start to move the toes and ankle dorsiflexion and dorsiextension exercises, as much as possible without increasing the pain, as many times as possible (2) Quadriceps isometric exercises – that is, do leg extension exercises to tighten and relax the thigh muscles, contract for 5 seconds and relax for 2 seconds each time, contract for 500-1000 times a day, spread out to morning, noon and night. See the figure below: (3) straight leg lift exercise, 1 set per day, 10-20 times per set, each leg lift lasts 1-3 minutes. See the picture below: It is best to keep the knee joint in the straight position when not doing exercises!!! Second, 3 days-1 month after surgery: (1) Continue quadriceps isometric exercises (2) Continue straight leg lifts: increase to 3 sets per day, 10-20 times per set, each leg lift lasts 1-3 minutes. Limited to morning training each day. (3)You can hold the crutches and wear the support to bear weight on the ground, and the weight-bearing force of the affected limb should not exceed 30% of the full weight-bearing force. (4) Knee flexion mobility exercises: knee flexion and extension under non-weight-bearing (prone position: lying down exercises) are beneficial to reduce swelling. 2-3 weeks after surgery: 30-45°; 4 weeks: 60°; 6 weeks: 90°. (5) Perform gluteus medius exercises for the lateral hip lift. (6) Perform gluteus medius training for posterior leg raise. (7) Increase the sandbag load training as the situation permits, and restore the muscle strength to 80% of the healthy side as much as possible within one month. (3) 1-2 months after surgery (1) Continue and strengthen the above exercises, so that the muscle strength can be restored to 80% of the healthy side. (2)Go to the crutches and wear the brace to walk 6 weeks after the surgery. (3)Balance training by standing with alternate foot support. (4) Mobility: 120° of knee flexion was achieved 2 months after surgery. 4. 2-3 months after surgery: (1) Continue to strengthen the above rehabilitation training, with more emphasis on strength and endurance training, the specific program should be changed according to the patient’s condition. (2) Start single-leg squat training to strengthen the lower limb strength. (3) Mobility: 3 months to return to the mobility of the healthy side. V. 3-4 months after surgery: (1)Continue to strengthen the above rehabilitation training,. (2)Half squat training (squatting horse stance), adjust the half squat position and training intensity according to your own muscle strength and pain location. (3) High leg raising training on the affected side. (4) Return to the hospital to review the MRI. Postoperative 4-6 months: (1) Continue to strengthen the above rehabilitation training, so that muscle strength recovery to the level of the healthy side. (2) Perform jumping training under the guidance of physician. 7. 6 months after surgery: (1) Continue to strengthen the above rehabilitation training. (2) Start jogging training. (3) Return to the hospital for MRI review. VIII. 9 months after surgery (1) You can engage in some non-competitive light sports activities (badminton,) (2) For special athletes, you need to perform the test of athletic ability and some special training. This program should be developed according to the different sports and should be discussed with the team doctor and coach. Note: 1, the use of braces: restrictive braces to protect the use of 3 months 2, walking with crutches for 6 weeks 3, ice: ice 15-30 minutes after the completion of rehabilitation training, 2 times a day; such as after training, such as skin temperature is too high can increase the number of ice 2-3 times, each interval of 2-3 hours. 4.Review time: monthly review in the first 3 months after surgery, and every 3 months thereafter, and MRI review in March, June, September and 18 months after surgery.