## Understanding Colles Fracture Deformity **Key Point:** Colles fracture is a dorsal angulation (dorsal displacement and dorsal angulation) of the distal radius fragment, NOT volar angulation. The classic deformity is described as a "dinner fork" appearance on lateral radiograph. ### Characteristic Deformities of Colles Fracture | Feature | Colles Fracture | Smith Fracture | |---------|-----------------|----------------| | **Angulation** | Dorsal angulation | Volar angulation | | **Displacement** | Dorsal displacement | Volar displacement | | **Radial deviation** | Present | Absent | | **Radial height loss** | Yes (must restore) | Yes (must restore) | | **Appearance** | "Dinner fork" (lateral view) | "Reverse dinner fork" | **High-Yield:** The mnemonic "**DORSAL**" helps recall Colles: - **D**orsal angulation - **O**ld age (typically elderly, osteoporotic bone) - **R**adial deviation - **S**hortening (radial height loss) - **A**ssociated with fall on outstretched hand (FOOSH) - **L**ateral view shows deformity best - **L**oss of radial inclination ### Why Each Feature Matters in Management 1. **Dorsal angulation** — Must be corrected to restore normal volar tilt (typically 11–12° volar) 2. **Radial height loss** — Critical to restore; loss of radial height leads to poor functional outcome and post-traumatic arthritis 3. **Radial deviation** — Must be corrected to restore radial inclination (typically 22–23°) **Clinical Pearl:** Failure to restore radial height and correct dorsal angulation leads to: - Loss of grip strength - Reduced pronation/supination - Post-traumatic wrist arthritis - Extensor pollicis longus (EPL) rupture (late complication) **Warning:** Volar angulation is the hallmark of a **Smith fracture** (reverse Colles), not Colles. Confusing these two is a common exam trap. [cite:Rockwood & Green's Fractures in Adults Ch 18]
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