A 28-year-old man presents with a fracture of the proximal third of the radius with an anterior dislocation of the radial head. A second patient has a fracture of the distal third of the radius with a dorsal dislocation of the ulnar head. Which clinical finding best distinguishes the first injury (Monteggia) from the second (Galeazzi)?

Explanation

## Distinguishing Monteggia from Galeazzi Fractures ### Key Anatomical Difference **Key Point:** The direction of the associated dislocation is the cardinal discriminator between these two fracture-dislocation injuries. ### Comparison Table | Feature | Monteggia | Galeazzi | |---------|-----------|----------| | **Fracture location** | Proximal or middle third of radius | Distal third of radius | | **Associated dislocation** | **Anterior** radial head dislocation | **Dorsal** ulnar head dislocation | | **Mechanism** | Fall on outstretched hand (FOOSH) with hyperpronation | Fall on outstretched hand with wrist extension | | **Radial bow** | Preserved | Disrupted | | **Stability** | Unstable | Unstable | ### Why Direction of Dislocation Matters **High-Yield:** The dislocation direction reflects the force vector and injury mechanism: - **Monteggia:** Hyperpronation force → anterior radial head dislocation - **Galeazzi:** Dorsiflexion + supination → dorsal ulnar head dislocation This directional difference is the most reliable clinical and radiological discriminator and guides reduction technique. ### Clinical Pearl **Clinical Pearl:** Both injuries are "fracture-dislocations" of the forearm, but the dislocation direction is pathognomonic for each. Missing the dislocation on initial radiographs is a common error — always check the radial head (Monteggia) and distal radioulnar joint (Galeazzi) on every forearm fracture film. ### Mnemonic **Mnemonic:** **M**onteggia = **M**iddle/Proximal radius + **Anterior** radial head; **G**aleazzi = **G**reat distal radius + **Dorsal** ulnar head. [cite:Rockwood & Green's Fractures in Adults 9e Ch 42]