| Anterior
Cruciate Ligament (ACL) Injuries Ligaments are the structures that ensure that the knee only flexes and extends (bends and straightens). The knee is not supposed to open up on the medial side (inside) or lateral side (outside). Neither is it supposed to slide forwards or backwards, or rotate. Ligaments prevent these abnormal motions. The ACL is one of the most important ligaments in
the knee . It has 2 main functions:
The ACL is a very commonly injured ligament, and it is estimated that about 100,000 ACL tears occur each year in the USA. Often the injuries occur when the person is changing direction quickly, or landing awkwardly after a jump. There may be a "pop" sound, and usually the athlete is unable to continue playing. The knee usually swells up in the next 1-2 days, and this swelling may last several weeks. The diagnosis is made by a good history taking, clinical examination, and usually an MRI (Magnetic Resonance Imaging) scan of the knee. ![]() Click here to watch a video of a patient with an ACL tear and an unstable knee. Unfortunately, most ACL injuries do not heal naturally on their own, and most patients require surgery to restore stability to their knees, to allow a return to sports and normal activities, as well as prevent future damage to other structures in the knee such as the meniscii (cartilage). Click here to proceed learn more about ACL reconstruction. Back to main patient information. |
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The ACL is one of the most important ligaments in
the knee . It has 2 main functions:
