What is often associated with an ACL tear… Usually includes a history of trauma, swelling and pain, limited motion, and joint instability 1) There must be a clear history of trauma, such as a sprain in basketball or soccer, a car accident injury, etc. 2) The knee is often swollen and painful within a few hours after the first injury 3) In acute injuries, the knee is often not fully extended 4) In chronic ACL injuries, the most common manifestation is the inability to run fast, stop and turn sharply, and therefore repeated sprains in sports