Courtesy: Kaye Wilkins MD and Lynn Staheli MD

 

Monteggia fracture-dislocation in Children

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Definition

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• A Monteggia lesion consists of:
  • Ulna fracture (or plastic deformation)
  • Radial head dislocation

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Important Note

• Term “Monteggia lesion” is preferred:
  • Includes both fracture and dislocation components

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Historical Background

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• Classified by José Luis Bado (1954)
• Bado classification:
  • Most widely used clinically

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Bado Classification

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Type I (Most Common)

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• Anterior radial head dislocation
• Ulna:
  • Apex anterior angulation

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Mechanism

• Hyperextension injury

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Key Concept

• Greenstick fracture:
  • Failure on tension side

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Type II (Rare)

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• Posterior radial head dislocation
• Ulna:
  • Posterior angulation

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Mechanism

• Flexion injury

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Type III

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• Lateral / anterolateral radial head dislocation
• Ulna:
  • Proximal metaphyseal fracture

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Mechanism

• Varus force on extended elbow

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Important Risk

• High risk of:
  • Posterior interosseous nerve injury

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Type IV (Very Rare)

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• Fracture of both:
  • Radius
  • Ulna

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• Associated with:
  • Anterior radial head dislocation

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Monteggia Equivalents

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Definition

• Variant injuries where:
  • Radial head alignment abnormal
  • But no obvious dislocation

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Examples

• Radial neck fracture + ulnar injury
• Plastic deformation of ulna

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Key Principle (Most Important)

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“Treat the ULNA first”

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Goals

• Restore:
  • Alignment
  • Length

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Result

• Radial head usually reduces spontaneously

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Mechanism of Injury (Tompkins Theory)

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Three Stages

1. Elbow hyperextension
2. Radial head dislocation
3. Ulna fails under tension — fracture

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Management Principles

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Step 1: Reduce Ulna

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• Correct angulation
• Restore length

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Methods

• 3-point molding
• Intramedullary fixation if unstable

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Step 2: Reduce Radial Head

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• Usually reduces after ulnar correction

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If Not Reduced

• Type I – Flexion
• Type II – Extension
• Type III – Valgus force

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Step 3: Maintain Reduction

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Immobilization

• Long arm cast

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Position by Type

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Operative Indications

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• Failure to reduce ulna
• Failure to reduce radial head
• Unstable fracture
• Plastic deformation not correctable
• Soft tissue interposition

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Why Radial Head May Not Reduce

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Most Common Cause

• Annular ligament interposition

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Other Causes

• Capsule
• Bone fragments
• Rare:
  • Nerve entrapment

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Complications

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Most Common

• Missed radial head dislocation

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Other Complications

• Malunion of ulna
• Re-dislocation
• Loss of pronation–supination
• Nerve injury (especially Type III)
• Chronic dislocation

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Chronic Monteggia Lesion

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Indications for Surgery

• Age <12 years
• Pain or deformity
• Loss of motion
• Progressive valgus deformity

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Treatment Steps

1. Ulnar osteotomy (correct deformity)
2. Reduce radial head
3. ± Annular ligament reconstruction

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High-Yield Exam Points

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• Type I – Most common
• Type III – Highest nerve injury risk
• Always check:
  • Radiocapitellar alignment

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Core Principle

• Ulna reduction = key step

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Most Common Complication

• Missed diagnosis

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Important Insight

• Plastic deformation:
  • Subtle but clinically critical

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Final Message

• Successful management requires:
  • Early recognition
  • Accurate ulnar alignment
  • Confirmation of stable radial head reduction