Meniscus injury includes acute injury, chronic injury, meniscus structural abnormality, etc. It is usually related to strenuous exercise, long-term chronic activities and other factors. 1. Acute meniscus injury: During strenuous activities, the knee joint causes impact to the meniscus, and the meniscus is easy to be extruded with acute injuries, which can be partial injuries or complete rupture. 2. Chronic meniscus injury: long-term chronic activities cause small injuries to the meniscus tissue, meniscus injury occurs after the involvement of the meniscus can appear meniscus partial tear, transverse fracture, longitudinal fracture and so on. 3. Abnormal meniscus structure: the strength, toughness and kinematics of discoid meniscus are changed to cause meniscus injury, which is a common cause of meniscus injury.