In a Monteggia fracture, which of the following is the MOST common location of the radial head dislocation?

Explanation

## Monteggia Fracture: Radial Head Dislocation **Key Point:** A Monteggia fracture is defined as a fracture of the proximal or middle third of the ulna combined with anterior dislocation of the radial head. This is the classic presentation and occurs in approximately 80% of cases. ### Classification (Bado) | Type | Ulnar Fracture Location | Radial Head Direction | Mechanism | Frequency | | --- | --- | --- | --- | --- | | I | Proximal/middle third | Anterior | Forced pronation + fall on outstretched hand | 60–80% | | II | Middle/distal third | Posterior | Forced supination + direct blow | 15–20% | | III | Metaphyseal (distal) | Anterior | Fall on outstretched hand in child | 5–10% | | IV | Fracture of radius + ulna | Anterior | Rare; both bones fractured | <5% | **High-Yield:** Type I (anterior dislocation) is by far the most common, accounting for 60–80% of all Monteggia fractures. The mechanism is forced pronation combined with a fall on an outstretched hand (FOOSH), which drives the radial head anteriorly. **Clinical Pearl:** Anterior dislocation in Type I is easily missed on initial radiographs if the lateral view is not carefully scrutinized. Always compare both forearms on radiographs. **Mnemonic:** **MONU** = **MON**teggia = **U**lna fracture + radial head dislocation (anterior in Type I).