1, what is the knee meniscus injury In the tibial joint surface there are medial and lateral meniscus shape bone, called meniscus, its edge part is thick, and joint capsule closely connected, the central part is thin, is free state. After meniscus removal, a thin and narrow meniscus with fibrocartilage can be regenerated by synovial membrane. The normal meniscus has the role of increasing the concavity of the tibial condyle and padding the femoral condyles, in order to increase the stability of the joint and play a role in cushioning shock. 2, what causes knee meniscus injury Mostly caused by torsional external force, when a leg bearing weight, calf fixed in semi-flexion, external booth, the body and the femur violently internal rotation, the medial meniscus between the femoral condyle and tibia, subject to rotational pressure, and cause meniscus tear. In severe trauma cases, the meniscus, cruciate ligament and collateral ligament can be injured at the same time. Site of meniscus injury. It can occur in the anterior, posterior, middle or marginal part of the meniscus. The shape of the injury can be transverse, longitudinal, horizontal or irregular, or even broken into intra-articular free bodies. 3, what are the symptoms of knee meniscus injury Most of them have obvious history of trauma. In the acute phase, there is obvious pain, swelling and effusion in the knee joint, and the joint flexion and extension activities are impaired, after the acute phase, the swelling and effusion can subside on their own, but there is still pain in the joint when moving, especially when going up and down stairs, going up and down slopes, squatting and standing, running, jumping, etc. The pain is more obvious, and in severe cases, there is limp or flexion and extension dysfunction, and some patients have “interlocking” Some patients have the phenomenon of “interlocking”, or a popping sound when flexing and extending the knee joint. 4, knee meniscus injury need to do what examination (1) X-ray examination: X-ray front and side film, although can not show the meniscus injury, but can exclude other bone and joint disorders. (2) Magnetic resonance imaging (MRI): This can clearly show the different parts of the meniscus and the degree of tearing. (3) Knee arthroscopy: Arthroscopy can directly observe the site and type of meniscal injury and other structures in the joint, which can help in the diagnosis of difficult cases. 5.How to treat (1) Acute stage: Some of the joints may have obvious fluid (or blood) accumulation, should be immediately iced, each time 30 minutes or more, depending on the swelling can be iced 3 to 5 times a day; fluid accumulation is more slow to subside, can be pumped out under strict aseptic operation; if the joint has “interlocking”, can stand or sitting rest gently kick leg If the joint is “interlocked”, it can sometimes be unlocked, but if it is still not unlocked by this method, the “interlocking” can be removed by manipulation and then protected with a functional knee brace for 3-4 weeks. During the fixation period and after the removal of the fixation, the quadriceps should be actively exercised to prevent muscle atrophy. (2) Chronic phase: If non-surgical treatment is ineffective, with obvious signs and symptoms and a clear diagnosis, the damaged meniscus should be repaired or removed under arthroscopic surgery as early as possible to prevent secondary cartilage damage and thus the occurrence of traumatic arthritis. After the operation, the knee should be bandaged in the extended position, and the quadriceps contraction exercises should be started the next day, and straight leg raising exercises should be started 2-3 days later to prevent quadriceps atrophy. ～Normal function can be restored in 2 to 3 months after surgery.