In a Monteggia fracture, which of the following best describes the anatomical injury pattern?

## Definition of Monteggia Fracture **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. ## Anatomical Pattern The injury consists of two components: 1. **Ulnar fracture** — typically at the proximal or middle third 2. **Radial head dislocation** — almost always anterior (volar) ## Bado Classification | Type | Ulnar Fracture Site | Radial Head Direction | Mechanism | | --- | --- | --- | --- | | I | Proximal/middle third | Anterior | Fall on outstretched hand (FOOSH) with hyperpronation | | II | Middle/distal third | Anterior | FOOSH with hyperextension | | III | Metaphyseal (distal ulna) | Anterior | Fall on flexed elbow | | IV | Proximal radius + ulna | Anterior | Rare; direct trauma | **High-Yield:** Type I (anterior dislocation with proximal ulnar fracture) is the most common variant, accounting for ~60% of Monteggia injuries. ## Clinical Pearl The radial head dislocation is often missed on initial radiographs if the ulnar fracture is obvious — always check the radiocapitellar line on lateral view. The radial head should align with the capitellum on all views. **Mnemonic:** **MONU** = **MOnteggia = Ulna fracture + radiO head dislocation (anterior)**