Monteggia fracture-dislocation

Background

• Proximal ulna fx with radial head dislocation
• Common in kids (different treatment for kids); rare in adults
• FOOSH
• Easy to overlook the radial head dislocation (will result in worse outcome)

Clinical Features

• Pain/swelling at elbow
• Radial head may be palpable in an anterolateral or posterolateral location
• Spontaneous relocation possible: must palpate directly over
• May be associated with radial nerve injury (wrist drop, inability to extend the fingers)

Complex Associated Injuries

• Terrible triad of elbow
  • Coronoid fracture
  • Radial head fracture
  • Posterior elbow dislocation
• Open fracture
• Olecranon fracture-dislocation
• LCL injury

Differential Diagnosis

Forearm Fracture Types

• Distal radius fractures
  • Colles' fracture
  • Smith fracture
  • Barton fracture
  • Radial styloid fracture
  • Distal radioulnar joint disruption
• Radia ulna fracture
• Isolated radius fracture (proximal)
• Isolated ulna fracture (i.e. nightstick)
• Monteggia fracture-dislocation
• Galeazzi fracture-dislocation
• Forearm fracture (peds)

Evaluation

X-ray of Monteggia fracture of right forearm, showing fracture of ulna and dislocation of radius.

• Inspect skin for open fracture
• Decreased ROM at elbow may indicate dislocation
• PIN neuropathy most commonly associated (hand deviates radially with wrist extension)

Adult Imaging

• Xray: AP, Lateral of elbow, forearm, wrist
• CT scan: Fractures involving coronoid, olecranon, and radial head
• Findings:
  • proximal 1/3 Ulna fracture + radial head dislocation (due to ulna shortening)
  • Radial head can dislocate anterior, posterior, or laterally

Pediatric Imaging

• Xray: AP, Lateral of elbow, forearm, wrist
  • Assess radiocapitellar line on every lateral radiograph of the elbow: a line down the radial shaft should pass through the center of the capitellar ossification center
• Findings: Radial head dislocation + proximal ulna fracture or plastic deformation of the ulna without obvious fracture

Management

• Consult ortho in the ED
• Long arm posterior splint with 90 degrees of elbow flexion and the hand in a neutral position
• Adults: likely requires ORIF
• Peds: possible long arm cast vs ORIF

Disposition

• If splinted and stabilized, can be discharged after consultation with Ortho
• Admit for:
  • Open fracture
  • Signs of neurovascular injury
  • Concern for compartment syndrome

Complications

• Consider open fracture (look for puncture wounds)
• Compartment syndrome
• Posterior Interosseous Neuropathy (PIN) - radial nerve branch; affects ~10% of Monteggia fractures
  • Purely a motor syndrome resulting in finger drop, and radial wrist deviation on extension.
• Malunion with radial head dislocation

See Also

• Forearm Fracture
• compartment syndrome