The 'unhappy triad' (O'Donoghue's triad) of knee injury classically involves rupture of which three structures?

• A PCL, LCL, and lateral meniscus
• B ACL, PCL, and patellar tendon
• C MCL, LCL, and ACL
• D ACL, MCL, and medial meniscus (or lateral meniscus per current evidence) ✓

Explanation

O'Donoghue's unhappy triad classically describes rupture of the ACL, MCL, and medial meniscus from a valgus/rotational force (e.g., a lateral blow to the knee in football). More recent biomechanical studies have shown that the lateral meniscus is actually more commonly torn than the medial meniscus in this injury pattern, as lateral meniscus tears frequently accompany ACL ruptures. However, the classic textbook triad remains ACL + MCL + medial meniscus, and this is still the expected answer on NEET PG.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.