Symptoms

ACL tears are often accompanied by a loud "pop". The injury is followed by immediate pain and swelling. Generally, a person with an ACL injury needs to be assisted during walking, the knee may also be very unstable and "give out".

After falling to the ground, the injured person usually needs help getting up. The knee begins to swell soon after the injury. It may also be unstable, sometimes collapsing or "giving out" when you walk. Pain and swelling usually last 2 to 4 weeks but a severe injury will not heal itself.