A 28-year-old man is brought to the emergency department after a motor vehicle accident. He has severe pain and swelling in his left forearm. Clinical examination reveals tenderness over the proximal ulna with visible deformity. X-ray shows a fracture of the proximal third of the ulna with anterior displacement of the radial head. Neurovascular examination is intact. What is the diagnosis and what is the most appropriate initial management?

Explanation

## Diagnosis: Monteggia Fracture **Key Point:** A Monteggia fracture is a fracture of the proximal or middle third of the ulna with an associated anterior dislocation of the radial head. This is a classic injury pattern that requires recognition and appropriate reduction. **High-Yield:** Monteggia fractures account for 5-10% of forearm fractures. The radial head dislocation is often missed on initial radiographs, leading to delayed diagnosis and poor outcomes. **Mnemonic:** **MONTEGGIA = Ulna fracture + Radial head dislocation (anterior)** ## Classification (Bado) | Type | Ulna Fracture | Radial Head Dislocation | Frequency | Prognosis | |------|---------------|------------------------|-----------|----------| | **Type I** | Proximal/middle 1/3 | Anterior | 60% | Good with ORIF | | **Type II** | Distal 1/3 | Anterior | 15% | Worse prognosis | | **Type III** | Metaphyseal | Anterior | 20% | Variable | | **Type IV** | Proximal radius + ulna | Anterior | 5% | Requires ORIF both | ## Pathophysiology The mechanism typically involves: 1. Fall on outstretched hand with forearm pronated and elbow extended 2. Direct blow to the posterior forearm 3. Force transmitted through the radius to the radial head 4. Disruption of the annular ligament and radiocapitellar joint capsule 5. Anterior displacement of the radial head ## Management Algorithm ```mermaid flowchart TD A[Monteggia Fracture Diagnosed]:::outcome --> B[Reduce radial head]:::action B --> C{Ulna fracture pattern?}:::decision C -->|Proximal/middle 1/3| D[ORIF ulna with plate]:::action C -->|Distal 1/3| E[ORIF ulna with plate]:::action C -->|Metaphyseal| F[Consider conservative vs ORIF]:::decision D --> G[Verify radial head reduction]:::action E --> G F --> G G --> H[Early mobilization]:::action H --> I[Good functional outcome]:::outcome ``` **Clinical Pearl:** Always obtain AP, lateral, and radial head-specific views to identify the radial head dislocation. A lateral view is critical—the radial head should be aligned with the capitellum. **Warning:** The radial head dislocation is missed in up to 25% of initial presentations. Always look for it, especially in children where it may be the only obvious finding. ## Treatment Principles 1. **Reduce the radial head** — usually reduces spontaneously once the ulna is aligned 2. **Fix the ulna fracture** — ORIF with plate and screws is the gold standard for adults 3. **Verify reduction** — confirm radial head alignment on post-operative imaging 4. **Early mobilization** — begin active ROM at 3-5 days to prevent stiffness 5. **Monitor for complications** — posterior interosseous nerve (PIN) injury, loss of pronation/supination ## Comparison: Monteggia vs Galeazzi | Feature | Monteggia | Galeazzi | |---------|-----------|----------| | **Bone fractured** | Ulna (proximal/middle) | Radius (distal) | | **Associated injury** | Radial head dislocation (anterior) | DRUJ dislocation (dorsal) | | **Radius status** | Intact | Fractured | | **Treatment** | ORIF ulna | ORIF radius | | **Prognosis** | Good with early ORIF | Good with early ORIF | [cite:Rockwood and Green's Fractures in Adults Ch 26]