Imaging for the Acromioclavicular (AC) Joint

Initial Imaging: Standard Radiography

• Standard radiography with anteroposterior (AP) views is the first-line imaging modality for evaluating AC joint pathology, and should include bilateral comparison views to assess vertical instability, as recommended by the American College of Radiology 1
• At least 3 views with 2 orthogonal projections should be obtained for trauma evaluation, according to the American College of Radiology 1

Key Technical Considerations

• Upright positioning is mandatory, as supine radiographs can underrepresent AC joint malalignment, as noted by the American College of Radiology 2

Advanced Imaging for Complex Cases

When to Use MRI

• MRI without contrast is the preferred modality for suspected labral tears or instability when radiographs are noncontributory, with a rated 9/9 appropriateness, as recommended by the American College of Radiology 1

Common Pitfalls to Avoid

• Never rely on AP views alone, as posterior dislocations (type IV) are frequently missed without axillary views, as warned by the American College of Radiology 1
• Avoid supine radiography, as it underrepresents malalignment, as advised by the American College of Radiology 2
• Ultrasound has minimal utility for AC joint assessment, with a rated 1/9 appropriateness, though it can exclude joint inflammation if fluid is detected, as stated by the American College of Radiology 1