First, meniscus injuries are divided into two categories: one type of injury caused by disc meniscus deformity, not necessarily need to have a history of trauma, but most have the performance of knee popping, with pain in the lateral knee joint, accompanied by limited extension or flexion squatting pain, especially in adolescents under 20 years old, the vast majority of disc meniscus injury, there will be a large lateral gap on the x-ray performance. The other category is common meniscal injuries, often with a history of sprains or jumping injuries. The general manifestation of meniscus injury is pain in the medial or lateral joint space. The pain is aggravated during walking, or during or after exercise, and relieved after rest. Physical examination: ① pain can be pressed into the joint space, but the skin itself is not painful; ② pain in hyperextension and hyperflexion, with severe limitation of the range of flexion and extension; ③ positive McDonald’s sign; ④ the joint can be slightly swollen. X-rays are not helpful for diagnosis. MRI can usually clearly show the site and extent of meniscal damage. The normal meniscus and cruciate ligament, whose hydrogen atoms are anchored to a dense grid formed by peptides cannot participate in MR imaging, so they are low signal on any sequence. The most reliable MRI sign to confirm a meniscal tear is the discontinuity that can be seen on the surface of the meniscus. This can be largely characterized by relying on symptoms and signs, but it is more difficult to determine the severity of the injury, which can be better described morphologically by MRI. Because of the protective effect of the meniscus on the knee joint, the current concept of treatment for meniscal injuries has changed from “simply removing the meniscus after injury” to “not removing it as much as possible, preserving it as much as possible, suturing it as much as possible, and even transplanting it if possible”.