During a teaching round on forearm fractures, a senior resident asks which is the most common site of the radius fracture in Galeazzi fractures. What is the correct answer?

Explanation

## Galeazzi Fracture: Anatomical Location **Key Point:** A Galeazzi fracture is defined as a fracture of the radius with dislocation of the distal radioulnar joint (DRUJ). The radius fracture occurs at a specific and consistent anatomical location. ### Most Common Site: Distal Third at the Junction The **distal third of the radius, specifically at the junction of the middle and distal thirds**, is the most common site of the radial fracture in Galeazzi injuries. This accounts for approximately 60–70% of all Galeazzi fractures. **Why this location?** - The junction of the middle and distal thirds is a zone of relative weakness - This is where the radial shaft transitions to the wider distal metaphysis - The interosseous membrane insertion changes at this level - The pronator quadratus muscle originates near this region, creating a stress concentration ### Anatomical Distribution of Galeazzi Fractures | Radial Fracture Site | Frequency | DRUJ Dislocation Type | Clinical Notes | | --- | --- | --- | --- | | Distal third (middle-distal junction) | 60–70% | Dorsal (most common) | Classic presentation | | Middle third | 20–25% | Dorsal or volar | Less common | | Proximal third | 5–10% | Variable | Rare; often missed | | Radial head/neck | <5% | Variable | Very rare | **High-Yield:** The "Galeazzi fracture" is defined not just by the radius fracture, but by the **mandatory associated DRUJ dislocation**. The fracture location determines the direction of DRUJ dislocation: - Distal third fracture → dorsal DRUJ dislocation (most common) - More proximal fractures → volar or variable dislocation ### Clinical Pearl **Warning:** The DRUJ dislocation is often **missed on initial radiographs** if the clinician is focused only on the obvious radial fracture. A true Galeazzi fracture ALWAYS has DRUJ involvement; if the DRUJ is normal, it is not a Galeazzi fracture. ### Mechanism Correlation The distal third location results from: 1. **Fall on outstretched hand (FOOSH)** with the forearm in pronation or neutral position 2. Impact force transmitted through the wrist to the distal radius 3. The radius fractures at the weak junction zone 4. Pronator quadratus contraction pulls the distal radius fragment volarly 5. The ulnar head is left dorsally, creating dorsal DRUJ dislocation **Mnemonic:** **"GD"** = **G**aleazzi → **D**istal third (and **D**orsal DRUJ dislocation) [cite:Rockwood & Green's Fractures in Adults Ch 25]