1. strengthen the protection of the affected limb in daily life 2. control the amount of exercise in daily life, in short, “walk normally, reduce the number of unimportant exercises”. try to strengthen the knee joint by all means, but basically ensure that “strength exercises are painless”. Principle”. Priority should be given to pain-free exercises. 3. If in a certain range of motion, due to pain (pain arc), nerve control of the muscles is reduced, so that the muscles controlling the movement of the joint in that range are never aroused (muscle dysfunction) and cannot be trained effectively, try to perform several exercises within the pain arc in order to arouse the movement of the relevant muscle groups. At this time, attention should be paid to control the pain generated during the exercise within the tolerable range, and pay attention to the timely application of an adequate amount of ice after the exercise, and give it adequate rest. 4.Strengthen the strength exercise of the healthy side of the limb to support the whole body weight and further share the weight of the affected limb. 5, if there are conditions should be in the exercise before doing adequate preparatory activities, muscle fever and then a larger amount of strength training, after the exercise should be more adequate muscle pulling, to prevent delayed muscle soreness, to promote the elimination of fatigue. Specific ways: 1, static squat: back against the wall, both knees and shoulder width, toes forward, squat to the tip of the knee and toe line perpendicular to the ground, the center of gravity is placed on the affected foot, their own squat depth, the basic control can be in about 2 minutes to reach the full extent of fatigue, the interval does not exceed 10 seconds, 5-10 consecutive groups, 2 groups of days. If you want to increase the difficulty, you can place a soft ball (no smaller than the size of a volleyball) between your back and the wall, and perform the same standard exercises. This method is suitable for all patients who have no limitations for lower limb weight bearing. If there is cartilage damage in the affected limb and pain will occur during the exercise, you can avoid the damage interval by fine-tuning the angle up and down and try to make the exercise not occur within the pain arc. If the strength reaches a certain level, you can increase the difficulty and the fun of the exercise by changing the way of static squatting to strengthen the practice effect and practicality. 2, resistance knee extension: sitting on the edge of the bed (chair or equipment), the affected side of the ankle weight, in full extension up to 70 degrees range of resistance knee extension exercises, the rhythm of the action fast on – a slight pause of 2 seconds – slow down, the weight to repeat the action 10-15 times in the range of up to full fatigue and does not produce pain is appropriate, such as fatigue and pain In case of conflict between fatigue and pain, give priority to pain control and extend the pause time in the movement to enhance the training effect. Rest half a minute for each 10-15 reps, 60-90 consecutive sets, 2 sets of days. This exercise can also be performed on the healthy side, but care should be taken to increase the range and load as appropriate to differentiate. For patients with early injury to the non-extended knee apparatus of the lower extremity (quadriceps, patella, patellar tendon) it is generally indicated. If the active extension of the affected limb is limited, emphasis should be placed on strengthening the resistance knee extension exercises from the hyperextension position to the 30 degree flexion position, strengthening the medial femoral muscle, with no change in the standard of movement. In fact, the last 30 degrees of joint control is the most significant in people’s daily work and physical exercise, and the strength of the medial femoral muscle in this area accounts for more than half of the strength of the entire muscle group, so in most cases the focus should be on exercises within this range of motion. 3. Resisted knee flexion: lying prone on the bed with weights or leather straps on the affected ankle, the maximum range of resisted flexion is performed with the same weights, movement specifications and number of exercises as the above “resisted knee extension” movement. The purpose of this exercise is to strengthen the posterior thigh muscles (N cord), as antagonists of the anterior quadriceps, the posterior muscles play an important role in maintaining overall joint balance and joint motion control, so it is important to pay attention to this exercise, but patients with posterior cruciate ligament reconstruction of the knee joint should not do this exercise for 3 months after surgery. Other patients are basically applicable, and this action does not cause increased pressure on the patellofemoral joint surface, even for patients with more serious degenerative osteoarthrosis is still applicable. 4, water exercises: back against the wall of the pool, hands on the shore, try to fix the body, the affected limb in the water efforts to extend the knee – flexion, repeated exercises 5-10 minutes times, the interval (rest) no more than half a minute, 3-6 times group, 3-5 groups of weeks with conditions. If you want to increase the difficulty, you can wear a flipper on your foot and perform the same exercises. When the function of the affected limb reaches a certain level, try to hit the water in freestyle position, time is not adjusted for the time being. This way is basically suitable for patients with weight-bearing limitation of lower limb, meniscus repair, cartilage weight-bearing area injury, severe patellofemoral arthropathy, tibial plateau fracture, femoral condyle fracture, tibial fracture and other fractures in the direction of weight-bearing, but attention should be paid to safety in the process of entering and leaving the water to prevent accidents, and it is not suitable for those who do not have conditions to ensure safety. 5. Single-leg support on the affected side (golden chicken independence): stand with one limb fully extended, thigh muscles fully contracted, knee joint “backward”, chest up, abdomen and hips up, keep balance, and try to take off the crutch when it reaches 1-2 minutes of stable standing without falling. Generally stand for 5 minutes / time, rest interval 10 seconds, 2-3 times / group, 1-2 groups / day. When standing for more than 5 minutes and still be able to ensure a smooth body, you can transfer to the balance board to continue this exercise, the standard remains the same. It is recommended that the balance board can be made in the following way: 4-5 empty mineral water bottles with tightened caps, tied with cloth into a row, placed on the ground, it becomes a single foot balance board, bipedal use to make two can. Just on to pay attention to safety, to prevent falls, strength can also be practiced on the board 0-45 ° half squat. This method is suitable for those who do not have any contraindications to lower limb weight-bearing, practice should try to ensure pain-free. 6, straight leg raise exercise: sitting or lying position, thigh muscles fully contracted, after locking the knee joint, straight leg raise to the heel 15M from the bed, hold until exhaustion, interval 10 seconds, 10 times / group, 3-5 groups / day. The key to this exercise is to fully straighten the knee joint, a slight bend in the exercise is much less effective. This method is applicable to almost all patients with lower extremity injuries except for knee extension device injuries. 7, quadriceps isometric contraction: that is, thigh muscle tension and relaxation. Do as much as possible without increasing pain. (More than 500 times/day) When practicing, place your hand on your thigh, especially slightly below the inner thigh, and experience the contraction of the medial femoral muscle, making sure that each contraction is clearly felt. This method of extension is still applicable to patients with knee extension device injuries, so just keep the force at a pain-free level when performing the exercise, while other patients can do their best. This exercise method has another significance: contracting the muscle can trigger the movement of the patellofemoral joint, thus maintaining the flexibility of the patella after the injury, which has a greater effect on preventing stubborn adhesions of the joint, and at the same time can ensure the normal elasticity of the muscle, which has a greater effect on the flexibility of the entire knee joint, and it is recommended that patients with various injuries practice diligently.