Anterior cruciate ligament injury

The anterior cruciate ligament is an important, internal, stabilizer of the knee joint, restraining hyperextension. The combination of "pop" during a twisting movement or rapid deceleration, together with inability to continue participation, and followed by early swelling, is said to indicate a 90% probability of rupture of the anterior cruciate ligament. A particularly severe form of the contact injury is called the "unhappy triad" and involves the anterior cruciate ligament, the medial collateral ligament, and the medial meniscus. The pivot-shift test, anterior drawer test and Lachman test are used during the clinical examination of suspected ACL injury, with the Lachman test having the highest sensitivity.