Unhappy triad

An unhappy triad (or terrible triad, or O'Donoghue's triad^[1]) is an injury to the knee. It commonly occurs in contact sports (such as American football). The mechanism for this injury occurs when a lateral (outside) force to the knee is received while the foot is fixed on the ground.

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Structures in triad

This scenario causes an injury to three knee structures:

• the anterior cruciate ligament
• the medial collateral ligament (or "tibial collateral ligament")
• the medial meniscus

The inclusion of the medial meniscus in the triad has been challenged.^[2]

The reason that the medial collateral ligament and medial meniscus are injured together is because they are attached to one another in the knee joint.

Terminology

The term "unhappy triad" was coined by O'Donoghue in 1950.^[2][3][4] However, since then the terms "unhappy triad" and "terrible triad" have also been used to describe several other combinations of joint injuries, including those of the elbow^[5] and shoulder.^[6]

The term "terrible triad" is also sometimes used in the popular press to describe conditions relating to pain, or even to refer to the MacDonald triad.

See also

• Anterior cruciate ligament injury
• Anterior cruciate ligament reconstruction

Additional images

References

1. ^ Shelbourne K, Nitz P (1991). "The O'Donoghue triad revisited. Combined knee injuries involving anterior cruciate and medial collateral ligament tears". Am J Sports Med 19 (5): 474-7. PMID 1962712.
2. ^ ^{a b} Barber F (1992). "What is the terrible triad?". Arthroscopy 8 (1): 19-22. PMID 1550645.
3. ^ O'Donoghue D (1950). "Surgical treatment of fresh injuries to the major ligaments of the knee". J Bone Joint Surg Am 32 (A:4): 721-38. PMID 14784482.
4. ^ O'Donoghue D. "The unhappy triad: Etiology, diagnosis and treatment". Am J Orthop 6: 242-7 PASSIM. PMID 14237439.
5. ^ Pugh D, McKee M (2002). "The "terrible triad" of the elbow". Tech Hand Up Extrem Surg 6 (1): 21-9. PMID 16520629.
6. ^ Simonich S, Wright T. "Terrible triad of the shoulder". J Shoulder Elbow Surg 12 (6): 566-8. PMID 14671520.