The knee joint is the hinge between the thigh and the calf, and it is the largest joint in the human body. It is formed by the joint capsule wrapping the lower femur, the upper tibia and the patella (kneecap) in front of it. The medial and lateral femoral condyles of the lower femur are hemispherical. When the knee joint moves, it rolls and slides on the smooth "platform" at the upper end of the tibia. In order to reduce friction and vibration and make the pressure evenly distributed, there is a cartilage "washer" between the two articular surfaces. The "pad" is crescent-shaped, one on each side, like a bracket. The "pad" is fixed on the tibial plateau with the joint capsule and the surrounding tendons and ligaments, and can move slightly back and forth or inside and outside with the movement of the knee joint. The proper term for "gasket" is meniscus. The medial meniscus has a thick outer edge and a thin inner edge; The lateral meniscus is slightly smaller than the medial meniscus, but it is plump and looks like the moon in the twelfth lunar month. Meniscus plays an important role and is easily damaged. Meniscus tear's injury may be caused when the lower limbs are loaded, the feet are fixed, the knees are slightly flexed, and the joints suddenly rotate in and out or extend the knees. In daily work and life, when you lift weights, or get off the bike in a hurry and stand unsteadily; Or in fierce sports such as football and basketball, meniscus injury may occur when athletes compete. Long-term squatting or semi-squatting work, such as car mechanics, repeatedly squatting and standing, meniscus wear is serious, and there will be damage. Most of these patients are young and middle-aged. In acute injury, someone can hear the noise in the joint by himself. It is often accompanied by synovial injury on the inner wall of joint capsule, which causes intra-articular bleeding and exudation. After the injury, the joint gradually swelled and the pain continued. After rest and general treatment of swelling and pain relief, the symptoms are relieved, but the joint space is still painful, especially when the joint flexes to a certain position. Walking, especially going up and down stairs, makes me feel weak in my lower limbs, and I often hit my legs and feel weak, which affects my work and life. After a long time, the thigh muscles atrophy and the circumference becomes thinner. When some patients walk, they suddenly feel abnormal pain in their knees, unable to move or even fall. Endure the pain, move the calf, and you can resume walking. This symptom is called joint atresia, which is caused by the injured meniscus blocking the joint. Some patients will feel bouncing in their knees and hear a click. A few special types of meniscus injuries can be repaired, and most of them are removed. By removing the damaged meniscus, the symptoms of the knee joint can be eliminated or significantly alleviated. As time goes on, a meniscus structure will grow in situ. Although it is worse than the original normal structure, it also has most functions. In order to promote recovery, quadriceps femoris should be exercised before and after meniscus surgery. The method is that the patient lies flat on the bed, straightens his lower limbs, forcibly lifts the kneecap (patella) upward, and then relaxes and repeatedly exerts force. Or straighten your lower limbs, raise, lower, and repeat. After a certain degree, you can also hang a sandbag with a certain weight on your ankle for practice. The quadriceps femoris is strong after exercise, which is beneficial to maintain joint stability. Exercise should start before operation and continue the next day after operation. At this time, the wound is still painful, and patients often have concerns, such as fear that the wound will crack and bleed inside. Be sure to eliminate your worries and exercise painfully. Two weeks after operation, the range of joint motion gradually increased. The degree of exercise is obviously related to the recovery effect. The better the exercise, the better the effect. Processing method: 1. If there is obvious hydrops (or hematocele) in the joint in the acute stage, the hydrops should be extracted under strict aseptic operation; If the joint is "locked", release the "locked" manually, and then fix the knee joint in a straight position for 4 weeks from thigh 1/3 to ankle with plaster (Figure 3- 135). Plaster should be properly shaped, and patients can walk with plaster. During and after fixation, the quadriceps femoris should be actively exercised to prevent muscle atrophy. 2. In the chronic stage, if the non-surgical treatment is ineffective, the symptoms and signs are obvious and the diagnosis is clear, the injured meniscus should be surgically removed as soon as possible to prevent traumatic arthritis. On the second day after operation, quadriceps femoris began to do static contraction exercise, and after 2 ~ 3 days, it began to do straight leg lifting exercise to prevent quadriceps femoris muscle atrophy. After two weeks, he began to walk on the ground and generally returned to normal function 2 ~ 3 months after operation. 3. The meniscus injury should be treated by arthroscopy, and the meniscus edge tear can be repaired by suture. Usually, the meniscus is partially removed and the undamaged part is retained. For those who are suspected of meniscus injury at an early stage, emergency arthroscopy is feasible, and meniscus injury can be treated at an early stage to shorten the course of treatment, improve the therapeutic effect and reduce the occurrence of traumatic arthritis. Arthroscopic surgery has the advantages of less trauma and quick recovery.