The terrible triad of the elbow is a severe elbow fracture-dislocation pattern and is so-called because it has poor medium-to-long term outcome. 

Epidemiology

The terrible triad primarily occurs in adults; the flexibility of ligaments in children makes this constellation unlikely ⁴. In the upper limb, the elbow is the second most dislocated joint after the shoulder, with fractures associated with ~25% of dislocations ⁵. 

Pathology

Mechanism

Most commonly due to a fall onto an outstretched hand, not necessarily high-energy, with the arm in semi-flexion and supination ³. The fall is usually associated with a valgus posterolateral force which disrupts the capsuloligamentous structures sequentially from lateral to medial ⁵. 

Radiographic features

The terrible triad of the elbow is the association of ^1,2:

1. elbow dislocation (anterior or posterior) 

2. coronoid process fracture 

3. radial head fracture

The posterior elbow dislocation usually involves the ulnohumeral joint ⁵. The coronoid fractures usually involve the tip or are type I fractures (O'Driscoll Classification). Up to 35% or 7 mm of the coronoid may be involved ⁵. 

Treatment and prognosis

Management can be non-operative or operative. 

Criteria for non-operative management include ⁵:

• concentric joint reduction

• no mechanical block associated with radial head fracture

• small coronoid fragment

• stable arc of motion up to 30^o from full extension

Operative techniques vary, depending on the injury pattern, but may include ⁵:

• coronoid

  • internal fixation or anterior capsular repair

  • may need grafting either from discarded radial head fragments (if performing radial head replacement) or olecranon process

• radial head internal fixation or replacement

• repair of lateral ulnar collateral ligament (LUCL) to restore lateral stability

• restore medial stability via medial collateral ligament (MCL) repair or use of external bracing