A 35-year-old woman is brought to the trauma bay following a fall from a 15-foot height. On primary survey, she is alert, RR 20/min, BP 118/76 mmHg, HR 92/min. During secondary survey, you note a tender swelling over the right shoulder, loss of shoulder contour, and the arm is held in adduction. Neurovascular examination is intact. Which investigation is most appropriate to confirm the diagnosis?

## Investigation of Choice in Suspected Shoulder Dislocation **Key Point:** Plain radiography with three standard views (AP, lateral, and axillary) is the investigation of choice to confirm shoulder dislocation and assess for associated fractures. ### Clinical Presentation Analysis The patient's presentation is classic for anterior shoulder dislocation: - Loss of shoulder contour ("squared-off" appearance) - Arm held in adduction and internal rotation - Tender swelling over the shoulder - Intact neurovascular status **High-Yield:** The three essential radiographic views are: 1. **AP (Anteroposterior)** — shows displacement of humeral head 2. **Lateral (Scapular Y)** — confirms anterior vs. posterior dislocation 3. **Axillary** — best view for visualizing humeral head position relative to glenoid ### Why Plain X-ray is First-Line | Criterion | Plain X-ray | Ultrasound | MRI | CT | |---|---|---|---|---| | **Confirms dislocation** | ✓ | ✓ | ✓ | ✓ | | **Detects fractures** | ✓ | ✗ | ✓ | ✓ | | **Speed** | Fastest | Fast | Slow | Moderate | | **Availability** | Always | Variable | Limited | Limited | | **Radiation** | Minimal | None | None | High | | **Cost** | Lowest | Low | High | High | | **First-line in trauma** | ✓ | ✗ | ✗ | ✗ | **Clinical Pearl:** Before reduction, always obtain plain radiographs to rule out associated fractures (Hill-Sachs lesion, Bankart lesion, greater tuberosity fracture). These findings may influence post-reduction management. **Mnemonic: AXIAL = Axillary view** — Essential for confirming dislocation direction and assessing glenoid rim involvement. ### When to Use Advanced Imaging - **MRI** — Post-reduction to assess soft tissue injury (rotator cuff, labrum) in recurrent dislocations or if considering surgical intervention - **CT** — Rarely needed; reserved for complex fracture-dislocations or when 3D anatomy is critical for surgical planning - **Ultrasound** — Useful in experienced hands for rapid confirmation but not standard in trauma protocols [cite:ATLS 10th Edition Ch 8, Rockwood & Green's Fractures in Adults 9e Ch 15]