## Investigation of Choice for Colles Fracture Diagnosis **Key Point:** Plain radiography remains the gold standard and first-line investigation for suspected distal radius fractures, including Colles fractures. ### Why Plain Radiography? 1. **Diagnostic accuracy**: Plain X-rays (PA, lateral, and oblique views) are sufficient to: - Confirm the fracture - Assess fracture pattern (simple vs. comminuted) - Evaluate displacement and angulation - Identify associated injuries (ulnar styloid fracture, intra-articular extension) 2. **Immediate availability**: Rapid imaging in emergency settings 3. **Cost-effective**: Low radiation dose, inexpensive 4. **Adequate for treatment planning**: Conventional radiographs provide all necessary information for initial management decisions ### When Are Advanced Imaging Studies Indicated? | Investigation | Indication | |---|---| | **CT scan** | Intra-articular extension, comminution assessment, preoperative planning for complex fractures | | **MRI** | Suspected soft tissue injury, ligamentous damage, occult fractures (rarely needed acutely) | | **Ultrasound** | Bedside assessment in resource-limited settings, assessment of soft tissue swelling | **High-Yield:** The "dinner fork" deformity is a clinical sign of dorsal displacement in Colles fracture. Radiographs confirm this and measure: - Radial height (normal ~11 mm) - Radial inclination (normal ~23°) - Volar tilt (normal ~11° volar; loss indicates dorsal angulation) **Clinical Pearl:** In a Colles fracture, the distal fragment is displaced dorsally and radially, with loss of volar tilt. Associated ulnar styloid fracture occurs in ~50% of cases and is best seen on PA view. **Tip:** Always obtain three views (PA, lateral, oblique) to avoid missing subtle fracture lines or intra-articular involvement. 
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