Monteggia Fracture Dislocation

Courtesy: Dr Amr Abdelgawad, University of Texas, El Paso, USA

Definition

Monteggia fracture–dislocation is defined as:

• A fracture of the proximal ulna

• Associated with dislocation of the radial head from:

  • The proximal radioulnar joint

  • The radiocapitellar joint

Key principle:
Any fracture of the proximal ulna must prompt careful assessment of radial head alignment.

---

Clinical Presentation

• Pain and swelling around the elbow and proximal forearm

• Deformity of the elbow or forearm

• Restriction of elbow movement

• Possible posterior interosseous nerve (PIN) palsy, presenting as:

  • Inability to extend the thumb

  • Weak finger extension

---

Clinical Examination

Posterior Interosseous Nerve Assessment

• Ask the patient to:

  • Extend the fingers

  • Dorsiflex the thumb

• Inability suggests PIN palsy

• PIN palsy is usually neuropraxia and often resolves after reduction

---

Radiographic Evaluation

Radiocapitellar Line (Most Important Rule)

• A line drawn along the long axis of the radius

• Must always bisect the capitellum

• Applies to:

  • All radiographic views (AP, lateral, oblique)

  • All age groups

? If the radiocapitellar line does not intersect the capitellum ? radial head dislocation

---

Radiographic Findings in Monteggia Injury

• Fracture of the proximal ulna

  • May involve the olecranon

• Abnormal relationship between the radial head and capitellum

• The radial head may be displaced:

  • Anteriorly

  • Posteriorly

  • Superiorly

  • Inferiorly

Direction may vary, but loss of radiocapitellar alignment confirms the diagnosis.

---

Role of Comparison Views

• Radiographs of the contralateral normal elbow can be extremely helpful

• Normal elbow:

  • Radiocapitellar line bisects the capitellum in all views

• Comparison improves diagnostic confidence, especially in young children

---

Post-Reduction Assessment

• Ulnar fracture alignment restored

• Radial head must be:

  • Congruent with the capitellum

  • Stable through range of motion

• Radiocapitellar line should again bisect the capitellum

• In children, ulnar fractures remodel well once alignment is achieved

---

Failed Closed Reduction

• If radial head does not reduce after closed manipulation:

  • Surgical intervention is required

• Common technique:

  • Intramedullary fixation of the ulna

  • Restores ulnar length and alignment

  • Allows spontaneous reduction of the radial head

---

Missed Monteggia Fracture–Dislocation

• Often misdiagnosed as an isolated ulnar fracture

• Late presentation may show:

  • Elbow deformity

  • Pain during activity

  • Limited motion

• Management usually requires:

  • Ulnar osteotomy

  • Open reduction of the radial head

  • Possible ligament reconstruction

• Outcomes are less predictable than acute cases

---

Treatment Principles

Acute Monteggia Fracture–Dislocation

• Urgent reduction is mandatory

• Restore:

  • Ulnar alignment

  • Radiocapitellar congruity

• Operative treatment indicated if:

  • Closed reduction fails

  • Radial head remains unstable

Chronic or Missed Monteggia

• Complex reconstructive surgery

• Higher complication rates

• Inferior functional outcomes

---

Key Take-Home Messages

• Always check the radiocapitellar line in pediatric elbow X-rays

• Proximal ulnar fracture + radial head malalignment = Monteggia fracture–dislocation

• Never label these injuries as isolated ulnar fractures

• Early diagnosis and reduction prevent long-term disability

• Missed Monteggia injuries convert a simple problem into a major reconstructive challenge