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Anterior Cruciate Ligament

Mechanism of Injury

The ACL is usually torn as a result of a quick deceleration, hyperextension or rotational injury that usually does not involve contact with another individual. This injury often occurs following a sudden change of direction. A person typically reports feeling a popping sensation in the knee. When hit from the side, injuries to the ACL are often associated with medial meniscus and medial collateral ligament (MCL) tears, collectively known as the “unhappy triad.” In adolescents, the ACL may avulse from the tibial spine instead of rupturing [ 14, 19, 21 ].