A 68-year-old woman from rural Maharashtra presents to the emergency department after a fall on her outstretched hand (FOOSH) while collecting firewood. On examination, the wrist shows a characteristic 'dinner fork' deformity with dorsal angulation and dorsal displacement of the distal fragment. The radial styloid is at the same level as the ulnar styloid. X-rays confirm a distal radius fracture with dorsal displacement. Which of the following best describes the fracture pattern and its typical mechanism?

Explanation

## Colles Fracture: Definition and Mechanism **Key Point:** Colles fracture is a dorsal (posterior) displacement of the distal radius fragment, classically caused by a FOOSH injury with the wrist in extension. ### Clinical Presentation The 'dinner fork' deformity is pathognomonic and results from: - Dorsal angulation of the distal fragment - Dorsal displacement (posterior subluxation) - Loss of radial height - Radial styloid at or below the level of the ulnar styloid (loss of radial prominence) ### Mechanism of Injury Colles fractures occur when: 1. Patient falls on an **extended wrist** (FOOSH with extension) 2. High-energy impact drives the distal radius dorsally 3. The fracture is typically **extraarticular** (though intra-articular variants exist) 4. Associated with osteoporosis in elderly patients ### Distinguishing Features from Smith Fracture | Feature | Colles | Smith | |---------|--------|-------| | **Displacement** | Dorsal (posterior) | Volar (anterior) | | **Deformity** | Dinner fork | Bayonet or garden spade | | **Mechanism** | FOOSH with extension | FOOSH with flexion or direct blow | | **Radial styloid** | Below ulnar styloid | Variable | | **Age group** | Elderly (osteoporotic) | Younger patients, high-energy | **Clinical Pearl:** The 'dinner fork' deformity is visible on lateral X-ray and is a hallmark finding that allows immediate clinical diagnosis even before formal imaging. **High-Yield:** Colles fracture = **Extension injury** → **Dorsal displacement**. Smith fracture = **Flexion injury** → **Volar displacement**. This mnemonic is tested repeatedly in NEET PG. ### Complications - Malunion with loss of radial height and angulation - Posterior interosseous nerve (PIN) compression - Extensor pollicis longus (EPL) rupture - Post-traumatic arthritis - Complex regional pain syndrome (CRPS) [cite:Rockwood & Green's Fractures in Adults Ch 18]