After a rotational injury to the knee, a patient hears a pop and notices that the knee is swollen within 60-90 minutes.
This is most likely due to injury to the?
a. Patella
b. Anterior cruciate ligament
c. Posterior cruciate ligament
d. Lateral collateral ligament
Answer B
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Anterior cruciate ligament (ACL) injuries are most often a result of low-velocity, noncontact, deceleration injuries and contact injuries with a rotational component. Contact sports also may produce injury to the ACL secondary to twisting, valgus stress, or hyperextension all directly related to contact or collision.
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Most ACL injuries may be diagnosed through a careful history emphasizing mechanism of injury coupled with a good physical examination. Remember that a previous ligamentous injury may be the cause of instability. When discussing the history, be sure to document mechanism of injury for this episode and any previous episodes.
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An audible pop often accompanies this injury, which often occurs while changing direction, cutting, or landing from a jump (usually a hyperextension/pivot combination).
Within a few hours, a large hemarthrosis develops. Patients usually are unable to return to play, secondary to pain, swelling, and instability or giving way of the knee.