A dislocated shoulder is a common, painful presentation. One ultrasound view from behind the patient shows whether the joint is out, which way it has gone, and whether your reduction has worked, at the bedside and without moving the patient.
Scan images in the graphic are illustrations, not patient scans.
The scan
- Sit the patient up and stand behind them.
- Use the curvilinear probe, or the linear probe in a slim patient.
- Feel for the scapular spine. Place the probe just below it and parallel to it, then slide laterally until the back of the joint fills the screen.
- Find the glenoid, a sharp bright edge on the medial side of the image. Find the humeral head, a smooth round bright curve lateral to it. Check which side of the screen is medial before you judge anything.
- Gently rotate the arm in and out, if pain allows, and watch the head turn in the joint.
Reading the view
- Normal. The humeral head sits level with the glenoid rim, curving round beside it. It turns smoothly as you rotate the arm.
- Anterior dislocation. The head has moved forward, so from behind it lies deep, further from the probe than the glenoid.
- Posterior dislocation. The head has moved backward, so it lies superficial, closer to the probe than the glenoid.
- After reduction. Return to the same spot. The head sits back level with the glenoid and turns as you rotate the arm.
What the scan does not tell you
Ultrasound shows position. It does not rule out a fracture of the greater tuberosity, the glenoid rim or the humeral neck. Follow your department's imaging policy, and X-ray when the mechanism, the patient's age or your examination raises concern for a fracture.