The meniscus is crescent-shaped, wedge-shaped in cross-section, a fibrocartilaginous tissue, between the femoral condyle and the tibial plateau, covering about 2/3 of the tibial plateau. Meniscus role:1. conductive load; 2. stabilizing effect; 3. cushioning effect; 4. synergistic lubrication effect. Etiology:The lateral meniscus injury is more common in oriental people and the medial meniscus injury is more common in western people, the reason may be related to the predominance of lateral disc meniscus in Asian people. The mechanism of meniscal injury lies in the paradoxical movement of the meniscus during knee movement and the suddenness of knee movement. Performance:Mostly seen in youth, the incidence is slightly higher in men than in women, and the incidence of lateral meniscus injury is about twice that of the medial meniscus. 1. History of trauma: Some patients have no obvious history of trauma. 2, pain: walking pain, mostly located on one side of the joint. 3. Interlocking:The joint is suddenly fixed in semi-flexion, and extension is impaired, but it can be flexed. 4. loss of control feeling: also known as playing soft leg, is a sudden feeling of joint discomfort, muscle control failure, can not or dare not bear weight, the tendency to kneel down. Examination: 1.X-ray, arthrography and MRI, etc. 2.Arthroscopy: It has the role of diagnosis and treatment. Treatment: 1.Acute treatment: Surgery is rarely considered. Blood can be drawn out of the joint cavity, bandaged with pressure, and the knee joint fixed in a long-leg cast for 3 to 4 weeks. 2. Surgical treatment: Surgery is considered for those who have interlocked joints and cannot be unlocked even after skin underdrawing. At present, surgery is mostly minimally invasive, i.e. arthroscopic surgery. Surgical methods include: meniscus repair or meniscectomy.