1.Passive knee straightening exercises sit and lie with the affected leg outstretched, take a towel roll and place it behind the ankle joint so that the heel is about 15 cm above the ground. Relax the leg muscles, rely on gravity to slowly straighten the knee joint, and maintain this position, adhere to at least 10 minutes. Practice 3 sets per day, 3 times per set. 2, standing gastrocnemius stretching exercises facing the wall, hands on the wall and shoulder height, legs in a lunge, keep the full foot on the ground, the affected leg in the back, body weight forward. Gently rotate the heel of the affected leg outward while continuing to tilt the body forward until there is a pulling sensation at the back of the calf, maintaining this position for about 15-30 seconds. Practice 3-5 sets of 3 times per day. 3, straight leg raise exercise semi-supine position, the healthy leg knee bend, the sole of the foot on the bed, the affected leg straight. Contract the quadriceps muscle of the affected leg with force, lift the leg off the bed about 20 cm, maintain the posture, the longer the better. Be careful not to bend the knee, do not lift the leg too high, and lower the leg slowly. Practice 3 sets of 10 times per day. 4, knee stability exercises to prepare about 1.5-2 meters long elastic band, knotted ends made of double-stranded ring, knotted end fixed in the doorway, the other end set in the ankle joint of the healthy side of the leg. First stand sideways to the door, so that the affected leg is close to the door and the healthy leg is far from the door. Make the healthy leg pull outward and pull the elastic band. Perform 3 sets of 10 reps per day. Stand facing the door again with your body weight on the affected leg and slightly flex the knee joint. Make the healthy leg push backward and pull the elastic band. 3 sets of 10 repetitions per day.