 I am Dr. Hemant Kalyan, consultant and head of the department of orthopedics and sports medicine working at Manipal Hospital, Bangalore. So the ACL is the shot for anterior cruciate ligament. Just to give you a little background before we answer the question, there are two cross ligaments like this in the knee which is inside the knee, the ACL is the anterior cruciate ligament which is the front of the cross and the PCL is the posterior cruciate ligament which is at the back of the cross. Now this ACL ligament is one of the most commonly injured ligaments especially in the younger people between the age of 18 to 40. In our practice, we see two common mechanisms of ACL injury. One is on the sports field in a game like racket sport like badminton tennis or squash or in a field game like football or even basketball and cricket as well. The second situation we see ACL injuries is during the road accidents especially involving two wheeler riders or pillion riders. Now there is a common link in the way the ACL gets injured either in the sports field or in the road accident situation and that is that the person who gets injured the foot will be on the ground planted and the body will twist on the planted foot. So take for example a sport situation. You are jumping to take a smash in badminton land on the right foot lose balance momentarily body twists on the right knee bang ACL can get injured. Take a two wheeler situation. There's a dog running across the road the two wheeler applied rider applies the brake there's a slight oil slick bike skids right leg reaches the ground he tries to balance himself on the bike falls of the bike body twists ACL can get injured. So basically it's a combination of a twisting injury on a foot which is planted on the ground.