During anterior cruciate ligament (ACL) rupture, the classic triad of injury (unhappy triad) involves which three structures?
- A ACL, posterior cruciate ligament, medial meniscus
- B ACL, medial collateral ligament, medial meniscus ✓
- C ACL, lateral collateral ligament, lateral meniscus
- D ACL, posterior cruciate ligament, lateral meniscus
Correct answer: B. ACL, medial collateral ligament, medial meniscus
Explanation
O'Donoghue's unhappy triad (terrible triad of the knee) classically involves the anterior cruciate ligament, medial collateral ligament, and medial meniscus — the three structures injured together by a valgus-external rotation force typically seen in contact sports. The medial meniscus is more vulnerable because it is firmly attached to the medial capsule and MCL, unlike the mobile lateral meniscus. MRI is the investigation of choice for confirming this combined injury pattern.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.