A 22-year-old falls on an outstretched hand with the elbow extended and supinated. X-ray confirms dislocation of the elbow. Which is the most common direction of elbow dislocation, and which two structures are injured in the so-called terrible triad?

• A Posterior dislocation; radial head fracture and medial collateral ligament tear
• B Posterolateral dislocation; radial head fracture and coronoid fracture ✓
• C Anterior dislocation; coronoid fracture and lateral collateral ligament tear
• D Medial dislocation; olecranon fracture and triceps avulsion

Explanation

Over 90 percent of elbow dislocations are posterior or posterolateral, occurring from a fall on the supinated outstretched hand. The terrible triad consists of elbow dislocation, radial head fracture and coronoid fracture, a combination that leaves the elbow grossly unstable because both the anterior column buttress and the secondary stabilisers are lost. The classic triad does not involve collateral ligament tears or olecranon fracture, though lateral ulnar collateral ligament injury often accompanies simple dislocations.

Reference: Rockwood and Green's Fractures in Adults, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.