The ACL stabilises the knee for chopping, twisting and leaping and pivoting exercise. The anterior cruciate ligament is in the middle of your knee joint. After you tear an ACL, you will often really feel or listen to a pop, experience the knee change from spot and create considerable swelling https://www.theorthopaedicandpainpractice.com/what-should-i-do-if-i-have-a-collateral-ligament-injury-of-the-knee/?_gl=1*xbbxlb*_up*MQ..&gclid=Cj0KCQjwkt6aBhDKARIsAAyeLJ2krYJSOuy5mZksrNqH-VDjQwW1ScD49yD8BUWysDG6u6bJPCSbXVUaAuCPEALw_wcB