The ACL tear is essentially caused due to injury or fall or contact sports. If a person is involved in high risk activities like contact sports, then they are advised to have strong musculature, especially in the quadriceps and the hamstrings, as this support the knee, hence preventing an ACL tear. If the patient has undergone an ACL reconstruction, or repair, surgery then they are instructed to strengthen their quadriceps as well as hamstrings before they go back into field, to prevent repeat tear of the ACL.