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Trauma & Fractures

Terrible Triad

Elbow Dislocation + Radial Head + Coronoid Fracture

A complex unstable injury requiring systematic surgical reconstruction

Understanding the Terrible Triad

Three Components

  1. 1. Elbow Dislocation - Usually posterior or posterolateral
  2. 2. Radial Head Fracture - Varying severity (Mason I-III)
  3. 3. Coronoid Fracture - Usually tip (Regan-Morrey Type I-II)

+ Lateral Collateral Ligament (LCL) tear - Always present

The terrible triad was named for its historically poor outcomes when treated non-operatively or inadequately. Modern understanding of elbow biomechanics and systematic surgical protocols have significantly improved results.

Mechanism

Typically results from a fall onto an outstretched hand with the elbow extended and forearm supinated. The axial load causes posterior dislocation, and the coronoid and radial head fracture as stabilizers fail sequentially.

Why Is It Unstable?

Coronoid

Provides:

  • • Posterior stability (buttress against dislocation)
  • • Varus stability
  • • Anterior capsule attachment
Radial Head

Provides:

  • • Valgus stability (secondary stabilizer)
  • • Posterolateral stability
  • • Longitudinal stability (DRUJ)
LCL Complex

Provides:

  • • Posterolateral rotatory stability
  • • LUCL is key component
  • • Always torn in terrible triad

When all three stabilizers are compromised, the elbow has no remaining restraints against posterior and valgus forces. Without surgical reconstruction, the elbow will repeatedly dislocate.

Surgical Treatment Protocol

1Fix the Coronoid

Restores posterior stability - even small fragments are important

  • • Suture lasso through anterior capsule (small tips)
  • • Screw fixation (larger fragments)
  • • Plate fixation (anteromedial facet fractures)
2Fix or Replace the Radial Head

Critical for valgus and posterolateral stability

  • • ORIF: If <3 fragments and reconstructable
  • • Replacement: If comminuted and unrepairable
  • • Never excise in terrible triad - leads to instability
3Repair the LCL

Restores posterolateral rotatory stability

  • • Primary repair with suture anchors to lateral epicondyle
  • • LUCL is the key component
  • • Repair through Kocher interval
4Assess Stability

Test under fluoroscopy through full ROM:

  • • Stable: Begin early protected motion
  • • Unstable in extension: Repair MCL and/or use hinged external fixator
  • • Grossly unstable: Static external fixator may be needed temporarily

Outcomes & Complications

Expected Outcomes

70-80% good to excellent results
Average flexion arc: 15-130°
Mayo Elbow Performance Score: 85+
Most patients satisfied with function
Some residual stiffness common

Potential Complications

Stiffness (most common - 50%+)
Recurrent instability (5-10%)
Heterotopic ossification (up to 40%)
Post-traumatic arthritis
Ulnar neuropathy

Evidence & References

• Hotchkiss RN. Fractures and dislocations of the elbow. In: Rockwood and Green's Fractures in Adults. 1996

• Ring D, Jupiter JB, Zilberfarb J. Posterior dislocation of the elbow with fractures of the radial head and coronoid. JBJS Am 2002

• Pugh DM, et al. The terrible triad of the elbow. J Hand Surg Am 2004

• Mathew PK, et al. Terrible triad injury of the elbow: current concepts. J Am Acad Orthop Surg 2009

Last Updated: January 2025 | Content reviewed by Dr. Deepthi Nandan Reddy, FRCS (Ortho)

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