Unhappy triad



Unhappy triad



Unhappy triad


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USMLE® Step 1 questions

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High Yield Notes

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Unhappy triad

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USMLE® Step 1 style questions USMLE

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USMLE® Step 2 style questions USMLE

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A 33-year-old man presents to the emergency department following a right knee injury. The patient was playing rugby when an opposing teammate tackled him. He felt a “pop” in the right knee and experienced pain after that. The patient is otherwise healthy. Physical examination demonstrates a large right knee effusion, a positive anterior drawer test, and a positive valgus stress test. Vital signs are within normal limits. An MRI of the patient's right knee is shown below. Which of the following is the most likely mechanism of injury that resulted in this patient’s condition?
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Anterior cruciate ligament (ACL) injury

“unhappy triad,” p. 459

Medial collateral ligament (MCL) injury

in “unhappy triad,” p. 459

“Unhappy triad”(knee injuries) p. 459

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An unhappy triad, also known as O'Donoghue's triad, is a common injury that occurs in the knee joint. It involves damage to the anterior cruciate ligament (ACL), medial collateral ligament (MCL), and medial meniscus. The injury usually occurs as a result of a sudden forceful twist or impact on the knee joint, such as during a sports activity. The lateral meniscus may also be involved in some cases. This injury is typically treated with surgery and physical therapy.


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