A 22-year-old footballer sustains a knee injury during a tackle. He has hemarthrosis, positive Lachman test, and MRI shows complete ACL tear with associated medial meniscus tear and medial collateral ligament injury. This triad is known as:

• A Terrible triad of the knee
• B Segond fracture complex
• C Posterolateral corner injury
• D O'Donoghue's unhappy triad ✓

Explanation

O'Donoghue's unhappy triad (classic description) involves injury to the ACL, medial collateral ligament (MCL), and medial meniscus, classically from a valgus external rotation force on a planted foot. More recent studies have found the lateral meniscus to be more commonly injured than the medial in ACL tears, but the O'Donoghue triad refers specifically to the ACL + MCL + medial meniscus combination. The 'terrible triad' of the elbow involves radial head fracture, coronoid process fracture, and elbow dislocation. Segond fracture is a lateral tibial plateau avulsion fracture pathognomonic of ACL injury.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.