The Anterior Cruciate Ligament (ACL) is one of the four main ligaments in the knee. The ligament connects the thigh bone to the shin bone, keeps the knee from hyper extending, prevents anterior dislocation at the tibia, and stabilizes to help prevent unnatural movement in the joint. If the knee is twisted, bent side to side, or hyper extended during physical activity the ACL can be injured. Contact sports involving rapid twisting movements may place harsh force on the knee, which can lead to injury.
There are several different types of ACL tears: a partial tear of the ligament, a complete tear of the ligament, also known as a rupture, and rarely the very end of the ligament remains attached to a small piece of bone which breaks or separates from the lower leg bone which is known as an avulsion. Many patients who sustain an ACL tear may opt to have surgical reconstruction of the ligament, which is most commonly performed arthroscopically.
Symptoms of a torn ACL will usually begin with swelling of the knee immediately after injury or within 24 hours. An ACL tear may cause a loud popping or cracking sound at the time of the injury. There may be some pain at the time of the impact, which over time may be felt in the calf region. The patient may feel some instability of the joint, perhaps creating the feeling of the knee "giving way."
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