The knee joint is the largest and most structurally complex joint in the body, consisting of the joint capsule wrapping the lower femur, upper tibia, and the patella (kneecap) in front. The meniscus is located on the tibial articular surface and has a medial and lateral meniscus shape. The medial meniscus is “C” shaped and the lateral meniscus is “O” shaped, with greater mobility than the medial meniscus. The meniscus is important as a joint filler, allowing the joint surfaces of the femoral and tibial condyles to fit together, reducing direct contact between the tibia and femur, preventing the joint capsule and synovial membrane from impinging during knee motion, and maintaining the stability of the normal knee joint. The knee joint is the most vulnerable of all joints in the body. The meniscus, on the other hand, is one of the most common injuries to the knee, with a predominance of young adults. When the lower extremity is weighted, in a position where the foot is fixed and the knee is slightly flexed, and the joint is suddenly internally rotated and extended or externally rotated and extended, it may cause a meniscal tear. In daily work, life, picking, lifting heavy objects, or riding a bicycle in a hurry to get off when standing unstable; or in intense soccer, basketball and other sports, athletes scrambling, may occur meniscal injury. Long-term squatting or semi-squatting work, such as auto mechanics, repeatedly squatting and standing up, the meniscus is severely worn and easily damaged. More than half of the cases have a history of knee “sprains”. When the injury is acute, some people can hear a ringing sound in the joint themselves. This is often accompanied by injury to the synovial lining of the joint capsule, causing intra-articular bleeding and oozing. After the injury, the joint gradually swells and continues to be painful. After rest and general treatment to reduce swelling and pain, the symptoms are reduced, but the pain often occurs in a certain position during sports, and may disappear after a change in position. The pain is located in the joint space on both sides. It is possible to walk, but weakness, especially when going up and down stairs, often playing soft legs, affecting work and life. The quadriceps muscle will gradually atrophy if the disease is long-lasting. Some patients suddenly feel abnormal pain in the knee joint when walking and cannot move, or even fall down. After tolerating the pain and moving the calf, they can resume walking again. This symptom is called joint interlocking, which is caused by the damaged meniscus jamming the joint. In some patients, the knee joint feels popping and popping sound is heard when moving. Treatment 1. Non-surgical treatment: Acute meniscal injuries are often treated conservatively. If the joint has significant fluid (or blood) accumulation, the fluid should be extracted under strict aseptic operation; if the joint is “interlocked”, it should be released by manipulation. After a period of rest and braking rehabilitation, the symptoms and signs can disappear. 2.Surgical treatment: If non-surgical treatment is ineffective, symptoms and signs are obvious and the diagnosis is clear, early surgery should be performed to prevent the occurrence of traumatic arthritis. After the operation, the knee extension position with pressure bandage, two weeks after the start of walking on the ground, generally in 2 to 3 months after the operation can return to normal function. The specific treatments for meniscal injuries can be divided into meniscal revision, partial meniscectomy, complete meniscectomy, meniscal repair, meniscal reconstruction, and discoid meniscoplasty. Arthroscopic management of meniscus injury is a less invasive procedure with quicker recovery. The difference in outcome after arthroscopic meniscectomy of the knee is related to the following factors: (1) the site and type of meniscal injury; (2) the amount of meniscal tissue removed; (3) the force line of the joint; (4) the degree of arthritis; (5) the degree of ligament stability; and (6) the age of the patient.