Terrible Triad of Elbow

Courtesy: Pierre Laumonerie MD, Paris, France

Overview

• Term “Terrible Triad of the Elbow” coined in 1996 by O’Driscoll.
• Involves posterior elbow dislocation, radial head fracture, and coronoid process fracture.
• Historically poor outcomes due to complex instability.

Anatomical Background

• Lateral Collateral Ligament (LCL) Complex:
  • Includes radial collateral ligament and ulnar collateral ligament.
  • Plays role in posterolateral stability, less in varus stability.
• Medial Collateral Ligament (MCL):
  • Anterior and posterior bundles.
  • Major contributor to valgus stability.
• Posterolateral Rotatory Instability (PLRI):
  • Key instability pattern in terrible triad.
  • First described by Regan & Morrey.

Mechanism of Injury

• Common mechanism: fall on outstretched hand with axial load, valgus stress, and supination.
• Radial head and coronoid fractures dissipate force, preventing complete dislocation in some cases.

Historical Understanding & Evolution

• O’Driscoll’s Circle of Hori:
  • Injury progresses lateral to medial.
  • Stages of instability based on sequential failure of soft tissue and bone.
• Newer model (Rüegsegger et al):
  • “Reverse Circle of Horii”—injury may begin medially.
  • Emphasizes MCL rupture and valgus force.

Surgical Principles

• Goal: Achieve elbow stability for early mobilization and function.
• Fixation of all components improves outcome:
  • Radial head
  • Coronoid process
  • LCL complex

Radial Head Fracture

• Usually results from impaction under the capitellum.
• Fixation Techniques:
  • Small central fragments removed.
  • Disimpaction followed by screw or tripod fixation.
  • Plates are used for comminuted or unstable neck fractures.
• Arthroplasty:
  • Preferred when reconstruction is not feasible.
  • Yields better results than overaggressive fixation attempts.

Coronoid Process Fracture

• Usually involves tip fracture (capsular attachment site).
• Term: “Capsular Fracture” reflects functional disruption.
• Treatment Options:
  • Non-operative in minor cases with stable elbow after other repairs.
  • Anchors or screws used if instability persists.
  • Retrograde screw or plate fixation in transverse or more severe fractures.

LCL and MCL Repair

• LCL (Lateral Ulnar Collateral Ligament):
  • Always repaired in terrible triad.
• MCL Repair:
  • Indicated in:
    • High functional demand (e.g. athletes)
    • Persistent valgus or posterolateral instability
    • Obese patients with gravitational varus stress
    • When radial head and LCL repair insufficient

Fixation Strategy Based on Stability Goals

• Fixation priority is joint stability, not just bone anatomy.
• “Fix it, Move it” principle:
  • More stable fixation allows earlier mobilization.
  • Leads to improved outcomes and lower osteoarthritis risk.

Summary & Modern Perspective

• The historical “terrible” prognosis is outdated.
• Better understanding of biomechanics has revolutionized management.
• Early, systematic fixation of key stabilizers—radial head, coronoid, LCL, and when needed MCL—is key.
• Emphasis on individualized approach based on:
  • Functional demand
  • Obesity and soft tissue stresses
  • Preoperative elbow stability