The ACL stabilises the knee for cutting, twisting and jumping and pivoting action. The anterior cruciate ligament is in the middle of the knee joint. After you tear an ACL, you'll often really feel or hear a pop, feel the knee change out of place and build substantial swelling in 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