I. Early stage (0~7 days after surgery) 1. On the day of surgery Ankle pump exercise: after the anesthesia subsides, start to move the toes and ankle joint. The method is forceful, slow, full range flexion and extension of the ankle joint, 5 minutes/group, multiple groups/hour. Li Zhihan, Center for Joint Surgery, Nanfang Hospital, Southern Medical University Quadriceps isometric exercises , if the pain is not obvious, it is feasible to practice muscle tensing and relaxation of the anterior thigh muscles. 2.Postoperative day 1 Ankle pump exercise , do as much as possible. Quadriceps isometric exercises: anterior thigh muscle tensing and relaxation exercises, do as much as possible without increasing pain (more than 500 times/day). N cord muscle isometric exercises: the affected limb below the knee on a pillow, so that the posterior thigh muscle tensing and relaxation to force down the pillow, as much as possible, more than 500 times / day. Postoperative day 1 can walk on crutches, but the affected limb should be under the protection of the splint, the affected limb crutches do not bear weight. 3, postoperative day 2 continue ankle pump exercises. Straight leg raising exercises: straighten the knee, straight leg raising to the heel 15cm from the bed, hold until exhaustion. 2~3 times/day. Lateral leg raising exercise, 10 times/set, 2 sets/day. Walking on crutches, but the affected limb should be under the protection of splints or supports, and the affected limb is not weight-bearing on crutches. 4, the third day after surgery, continue the above exercises. Weight-bearing balance exercises: separate the feet under the protection of crutches, move the center of gravity alternately from side to side within the range of micro-pain, 5 minutes / times, 2~3 times / day. Flexion exercises, the patient tries to sit on the edge of the bed, and naturally lower the knee joint to 30° within the range of micro-pain. 5.Postoperative day 4 Continue the above exercises. Strengthen the knee joint weight-bearing balance exercises: gradually until the affected limb can stand on one foot. If you can do it easily, you can start to walk with a single crutch (support on the healthy side). Be careful not to walk fully weight-bearing, only one-third of the weight of the affected limb. Flexion exercises to 0 ° ~ 60 ° range. 6. On the 5th day after surgery, continue the above exercises. Flexion exercises to 70°~80° range, and active flexion and extension exercises can be started. Stretching exercises: lie on your back, put a pillow at the heel of the foot, make the affected limb leave the bed completely, relax the muscles to make the knee joint stretch naturally, 10 minutes/times, 1~2 times/day. 7. On the 6th~7th day after surgery, continue the above exercises. Passive flexion exercises to 90° range, active flexion and extension exercises can also be up to 90°. Stretching Exercise Lie on your back, put a pillow at the heel of the foot, make the affected limb leave the bed completely, relax the muscles to make the knee joint stretch naturally, 10 minutes/times, 1~2 times/day. Initial period (2~4 weeks after surgery) 1. 2 weeks after surgery Passive knee flexion to 100°. Strengthening muscle strength exercises, a straight leg raising exercises up to 6 minutes. Walking with crutches and one-third weight bearing on the affected limb. 2.3 weeks after surgery Passive flexion to 110°. Strengthen active flexion exercises. Strengthen muscle strength exercises. Sitting or lying position holding the knee flexion exercise hold the knee to the beginning of pain to hold 10 seconds, slightly relax and rest for 5 seconds, and then hold the knee, repeat the exercise for 20 minutes, once a day. Walking on crutches, one-third of the weight of the affected limb. 3, 4 weeks after surgery Sleeping without splint or brace. Passive flexion to 115°. Start squatting or sliding exercises against the wall. Strive to achieve normal gait walking. Walking with crutches and one-third of the weight of the affected limb. Third, the middle stage (5 weeks to 3 months after surgery) 1, 5 weeks after surgery Passive knee flexion to 120 °. Exercise on stationary bicycle No load to light load, 30 minutes/time, 2 times/day. Walking with crutches and one-third weight bearing on the affected limb. 2.6~8 weeks postoperatively Passive knee flexion up to 150°, i.e., full range of the same as the healthy leg. Full weight bearing can be started at 8 weeks postoperatively. Attempt full squatting movements under protection. Strengthen muscle strength exercises, increase the number of straight leg raising exercises and static squatting exercises. 3.10 weeks~3 months after surgery Splint or brace can be removed. The angle of active knee flexion is the same as that of the healthy leg, and there is no obvious pain. Flex the knee in the prone position so that the heel touches the buttock, and keep stretching for 10 minutes/time. Start kneeling exercises and pedal exercises. Posterior period (4~6 months) Rehabilitation objective: to fully resume daily life activities; to strengthen muscle strength and joint stabilization. Rehabilitation precautions: Use a large load (i.e., the load of fatigue after completing 12 movements), 8~12 times/group, 2~4 consecutive sets of exercises, rest 90 seconds between sets, until fatigue. Exercise program: Continue the above exercises. Knee wrapping exercises. Jumping up and down exercises. Lateral hops. Start swimming, jumping rope and jogging. Athletes can begin practicing basic movements in specialized sports. Wear knee pads for protection during strenuous exercise. V. Recovery period (7 months~1 year after surgery) Purpose of recovery: gradually resume exercise at 7 months after surgery; improve maximum strength at a later stage. Starting from 10 months after surgery, full recovery of sports or strenuous exercise; gradually resume special training; strengthen muscle strength and stability of joints in strenuous activities; muscle strength of the affected side reaches more than 85% of the healthy side, and there is no pain and obvious swelling during exercise.