Meniscal injuries are very common sports injuries, but most patients who suffer from meniscal injuries have little understanding of the injury, which leads to two harmful situations: one is too fearful, stressful, and not getting proper treatment; the other is too dismissive, thinking it is a simple sprain and not receiving regular treatment, leading to later joint dysfunction or long-term pain. Anatomical structure: The meniscus is an important structure of the knee joint and is named for its shape, which is approximately half-moon. The meniscus is a layer of fibrocartilage located in the interstitial space of the knee and is important for joint function. The morphologic characteristics of the meniscus allow the spherical femoral condyle and the flatter tibial plateau to form a “matched” joint. The meniscus also includes the following important functions: increasing knee stability, cushioning, absorbing and transmitting knee loading forces, and promoting intra-articular nutrition. During weight-bearing, approximately 70% of the weight-bearing area is on the meniscus, which greatly reduces the stress on the tibial plateau, thus protecting the cartilage and the whole joint. In addition, the meniscus has functions such as lubricating the joint. The meniscus can evenly coat the joint surface with joint fluid, which greatly reduces the coefficient of joint friction. If the meniscus is removed, the peak pressure on the tibial plateau can increase twofold and will cause cartilage degeneration. It is these important functions of the meniscus that ensure years of weight-bearing movement of the knee without injury. Clinical manifestations: Patients have a history of sudden knee rotations, sprains when jumping and landing, or multiple knee sprains, swelling and pain. There is a tearing sensation in the affected knee at the time of injury. This is followed by joint pain, swelling, and blood accumulation in the joint. The pain is usually on one side or behind the joint and is more fixed in position. There is pressure pain in the joint space, sometimes accompanied by a ringing sound. Some patients experience joint interlocking (impaired extension and flexion), instability or slipping sensation (commonly known as hitting a weak leg), which is apparent when walking up or down stairs. In the later stages of the injury, the quadriceps muscle atrophy muscle strength is reduced and the leg becomes thinner. Meniscal injuries sometimes combine with cruciate ligament and collateral ligament injuries of the knee, and when combined with ligament injuries, joint instability may be manifested. Hyperextension and hyperflexion tests of the knee joint may cause pain and a positive gyratory compression test. After the injury, there is severe pain in the knee joint, inability to straighten itself, and swelling of the joint. The pressure pain at the knee joint gap is an important basis for meniscal injury. Diagnosis: The diagnosis can be made on the basis of medical history, clinical manifestations and physical examination. Generally, the following tests are still needed: 1, joint space pressure pain sign: the damaged meniscus adjacent parts of the joint space pressure pain, the positive rate is high, the clinical significance is the largest; 2, wheat test: supine position examination, flexion of the hip and knee, the examiner in the process of extension and flexion of the knee joint on the calf to apply internal rotation inward, abduction extension, external rotation abduction, inward extension and other forces, such as pain or popping sound is positive. The test is the most widely used clinical examination method, but in recent years it has been found that its positive rate is lower than that of the joint gap pressure pain sign; 3, Apley test: prone position examination, the affected knee is flexed at 90°, the examiner presses down hard on the ankle and makes rotational grinding, it is positive when there is pain in a certain position, and some cases can be positive. 4.Magnetic resonance imaging (MRI): It is an important test to diagnose meniscal injury, with an accuracy rate of more than 90%. It can not only confirm the diagnosis, but also determine the tear pattern and scope, and guide the development of treatment and rehabilitation programs. 5.Arthroscopy: The most accurate examination method, but it is invasive and is generally used as a treatment tool only when there are clear indications. Disease treatment 1.Acute stage. Rest, symptomatic pain medication application, if necessary, brace fixation. Generally after 4 weeks, you can walk with partial weight bearing under the protection of the brace, and gradually to full weight bearing. During the rehabilitation period, to actively exercise the quadriceps muscle to prevent muscle atrophy. However, most meniscus injuries cannot be rehabilitated, only a few meniscus edge “red zone tear injury has the possibility of self-healing, most meniscus injuries can not be repaired. It becomes chronic. 2. Chronic phase. In the chronic phase, the torn meniscus can damage other structures of the knee joint and cause traumatic arthritis. Therefore, diagnosed meniscus injury, if non-surgical treatment is ineffective and signs and symptoms are obvious, early surgery should be performed. The current conventional procedure is arthroscopic meniscus suture or partial resection. You can go down to the ground on the 2nd day after surgery, and you can basically return to normal function 1 month after surgery.