In a Monteggia fracture, which is the most common type and involves fracture of the proximal third of the ulna with anterior angulation?

Explanation

## Monteggia Fracture Classification **Key Point:** Monteggia fractures are classified into four types based on the location and angulation of the ulnar fracture and the direction of radial head dislocation. ### Type I (Anterior Angulation) — Most Common - **Frequency:** 60–70% of all Monteggia fractures - **Mechanism:** Forced pronation or fall on outstretched hand (FOOSH) with elbow flexion - **Fracture site:** Proximal or middle third of ulna with **anterior angulation** - **Radial head dislocation:** Anterior - **Age group:** More common in children ### Comparison of All Types | Type | Ulnar Fracture Location | Angulation | Radial Head Dislocation | Frequency | Mechanism | |------|------------------------|-----------|------------------------|-----------|----------| | I | Proximal/middle third | Anterior | Anterior | 60–70% | Pronation, FOOSH | | II | Middle/distal third | Posterior | Posterior | 15–20% | Direct blow, fall | | III | Metaphyseal (distal) | Variable | Anterior | 10–15% | Direct trauma | | IV | Both radius and ulna | Variable | Anterior | 5–10% | High-energy trauma | **High-Yield:** Type I is the **most common** and **easiest to reduce** closed. Type II has the **worst prognosis** and highest rate of complications (stiffness, nonunion). **Clinical Pearl:** Always check for radial head dislocation on imaging — it is the defining feature that distinguishes Monteggia from a simple ulnar fracture. Missed radial head dislocation is a common error leading to poor outcomes. **Mnemonic:** **MAD** — Monteggia Anterior (Type I) is most common and Dislocation of radial head is the key feature.