High impact athletic activities that put stress on the knee are the most common causes of ACL tears. This can include abrupt stops or pivots, an awkward landing from a jump, or a direct blow to the knee. ACL tears can also occur in car accidents or falls.
When an ACL injury occurs, a popping or tearing sensation in the knee will be noticed immediately, followed by pain and swelling. The knee may also feel unstable and unable to bear weight.
A physical exam will take place to check the knee for swelling and pain. Range of motion and function will also be assessed. Imaging tests such as x-rays and MRIs may be used to rule out bone fractures or to show the extent of the injury to the knee.
A torn ACL should be treated immediately to reduce pain and swelling. Conservative options include rest, icing, knee bracing, and physical therapy. Surgery may be recommended for athletes who plan to continue playing sports or when the knee continues to buckle during routine activity.