The meniscus is a crescent-shaped fibrocartilage within the knee joint, located between the joint surface formed by the tibia and femur, increasing the contact area between the femoral condyle and tibial plateau, thus increasing knee joint stability. The meniscus is divided into the anterior horn, the body and the posterior horn. Its function is to stabilize the knee joint and to transmit knee loading forces. It is the stabilizing load played by the meniscus that ensures years of weight-bearing movement of the knee joint without injury. Injury to the meniscus is mainly caused by indirect violence. Simply put, if the knee is twisted in and out during knee flexion and extension, there will be contradictory movements of the meniscus itself, leading to injury. How can I tell if there is damage to the meniscus? Meniscal injury is determined by the patient’s symptoms, physical findings and imaging. After the injury occurs, the patient shows pain in the joint space, ringing, or even limited knee movement due to joint interlocking and inability to straighten or squat. Physician examination can find obvious joint space pressure pain, prominence, characteristic examination including swaying test, McSign, etc. helps physicians to judge. For some patients whose symptoms and examination are not clear, knee x-ray imaging or MRI can be done, which has a higher positive diagnostic rate. How to treat meniscus injury? According to the different parts of meniscus injury, it is divided into anterior horn, body and posterior horn injury, while according to the different types of injury, it can be divided into longitudinal, laminar, transverse, oblique, degenerative and compound tears, etc. For meniscus injuries without symptoms can be temporarily observed, but attention should be paid to strengthening the leg muscle strength exercises to make the joint more stable. For patients with obvious symptoms or athletes with high requirements for lower limb activities, surgery should be performed as early as possible; otherwise, it is easy for the wear and tear of the broken meniscus to cause secondary damage to the articular cartilage and accelerate degenerative joint changes. Depending on the site and type of damage to the meniscus, the surgeon can perform arthroscopic procedures such as suturing, shaping and resection of the meniscus.