There are several causes of meniscal tears: First, trauma: the most common is acute trauma-induced meniscal tears, such as when playing strenuous sports or confrontational activities, such as soccer or basketball, when the knee joint is in a semi-flexed rotational position, it is very easy to cause a sprain or tear of the meniscus. Second, congenital diseases: Meniscus tears may be caused by congenital variants, such as discoid meniscus, which is shaped like a pancake. There is too much meniscus tissue between the femur and tibia, and this tissue is squeezed by the femur and tibia, which can cause tears in the discoid meniscus due to the squeezing. Third, aging disease: Due to degenerative meniscus tears in old age, mainly due to age, the quality of meniscus decreases, and degenerative tears may occur under slight external force.