Unhappy triad
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Overview
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.
Structures in triad
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 lateral meniscus
The inclusion of the lateral meniscus in the triad has been recently ascertained as it previously had been incorrectly postulated that the medial meniscus was the third component.[2]
Terminology
Terminology
The term “unhappy triad” was coined by O’Donoghue in 1950.[2][3][4] However, since then, this term and the term “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.
MR images demonstrate O’Donoghue’s unhappy triad
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ACL tear -
Medial meniscal tear -
Medial meniscal tear Image: -
Medial collateral ligament tear
Additional images
Additional images
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Left knee-joint from behind, showing interior ligaments. -
Capsule of right knee-joint (distended). Posterior aspect.
References
References
- ↑ 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.
- ↑ 2.0 2.1 Barber F (1992). “What is the terrible triad?”. Arthroscopy. 8 (1): 19–22. PMID 1550645.
- ↑ 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.
- ↑ O’Donoghue D. “The unhappy triad: Etiology, diagnosis and treatment”. Am J Orthop. 6: 242-7 PASSIM. PMID 14237439.
- ↑ Pugh D, McKee M (2002). “The “terrible triad” of the elbow”. Tech Hand Up Extrem Surg. 6 (1): 21–9. PMID 16520629.
- ↑ Simonich S, Wright T. “Terrible triad of the shoulder”. J Shoulder Elbow Surg. 12 (6): 566–8. PMID 14671520.
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