Meniscus injury is a very common sports injury, but most patients who suffer from meniscus injury know little about the injury, which leads to two harmful situations: one is too afraid, the heart is stressed, the urgent illness is not treated properly; one is too lightly, think it is a simple sprain, do not receive regular treatment, resulting in late joint dysfunction or long-term legacy of pain. The meniscus is an important structure of the knee joint, and its shape is approximately half-moon, hence the name meniscus. Simply put, the meniscus is a layer of fibrocartilage located in the knee joint space that plays an important role in joint function. The morphological characteristics of the meniscus allow the spherical femoral condyle and the flatter tibial plateau to form a more “compatible” 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 joint as a whole. Clinical presentation and diagnosis Patients tend to have a history of sprains when the knee is suddenly rotated, jumped up and landed, or have a history of multiple knee sprains, swelling and pain. There is a tearing sensation within 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 painful pressure 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. Disease diagnosis The diagnosis can be made basically based on medical history, clinical manifestations and physical examination. Generally, the following tests are still needed: 1. Inter-articular pressure pain sign: pressure pain in the inter-articular space near the damaged meniscus has a high positive rate and the greatest clinical significance; 2. McKay’s test: supine position examination, flexion of the hip and knee, the examiner in the process of extension and flexion of the knee joint to the calf to apply the force of internal rotation induction, abduction extension, external rotation abduction, internal rotation extension, etc., if there is 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 90°, the examiner in the ankle force downward pressure and rotational grinding, in a certain position when there is pain is positive, some cases can be positive. 4.Magnetic resonance imaging (MRI): It is an important test for diagnosing 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. Treatment 1.Acute stage: If the joint swelling is obvious, indicating a lot of blood accumulation, the fluid can be extracted under strict aseptic operation, and the elastic bandage is slightly compressed and wrapped; if the joint has interlocking, you can try to lift it by manipulation in a regular hospital. Cold compress treatment after the injury is important, while the affected limb needs to be elevated to rest. External fixation is usually required to keep the affected knee in extension for 4-6 weeks using a long-legged external fixation, either a tubular cast or a brace, to ensure good shaping and reliable fixation. Partial weight bearing is usually possible after 4 weeks with the protection of a brace and gradually to full weight bearing. During the rehabilitation period, the quadriceps muscle should be actively exercised to prevent muscle atrophy. 2. Chronic phase: In the chronic phase, the torn meniscus can damage other structures of the knee joint and cause traumatic arthritis. Therefore, a clearly diagnosed meniscal injury should be treated with early surgery if non-surgical treatment is ineffective and signs and symptoms are obvious. The current conventional procedure is arthroscopic meniscus suture or partial resection. Normal function can be basically restored 2 to 3 months after surgery.