I tore my ACL in my young 20's playing basketball. After the injury my knee was unstable and popped out of place about twice a year. Eventually I started cycling, and my instability problem went away. Cycling strengthened my quads which helped stabilize my knee. After a cross country bike tour my legs were huge and my ACL was stabilized for years. Later I started fighting, and stopped cycling which caused a reinjury to the knee. This time I tore two meniscus. Once an ACL is torn one is more likely to tear meniscus, due to instability...so get it fixed before it gets worse.