What is the best imaging modality for evaluating shoulder pain?

Best Imaging for Shoulder Pain

Radiography (X-ray) is the mandatory first imaging study for all patients presenting with shoulder pain, regardless of suspected pathology, and should include a minimum of 3 views: anteroposterior (AP), Grashey, and either axillary or scapular Y projections. 1, 2

Initial Imaging Approach

• Plain radiographs must be obtained first in every patient with shoulder pain before considering any advanced imaging, as they effectively identify fractures, dislocations, arthritis, calcific tendinitis, and massive rotator cuff tears that alter management 1, 2
• The standard radiographic series should include at least 3 orthogonal views to avoid missing fractures or dislocations 1, 2
• Specialized views may be added based on clinical suspicion: Rockwood or outlet view for impingement, Westpoint view for bony Bankart lesions, and Stryker notch view for Hill-Sachs deformities 1

Advanced Imaging Based on Clinical Scenario

When Radiographs Show Fractures

• CT without contrast (rating 9/9) is the next appropriate study to characterize fracture complexity, displacement, angulation, and guide surgical planning 1, 2
• Three-dimensional CT reformations are particularly valuable for scapular fractures 1

When Radiographs Are Normal: Suspected Rotator Cuff Pathology (Age ≥35 years)

• MRI without contrast and ultrasound are equally appropriate first-line studies (both rated 9/9) for evaluating rotator cuff tears, bursitis, or biceps tendinopathy 1, 2
• The choice between MRI and ultrasound depends on local expertise availability 1
• MRI demonstrates high sensitivity and specificity for full-thickness tears and can assess muscle atrophy, fatty infiltration, and tendon retraction—critical factors for surgical decision-making 1
• Ultrasound has 82% positive predictive value for rotator cuff tears but completely misses bone contusions and instability 3

When Radiographs Are Normal: Suspected Labral Tear/Instability (Age <35 years)

• MR arthrography (rating 9/9) is the reference standard for evaluating labral tears and chronic instability in the subacute or chronic setting 1, 2
• MRI without contrast (rating 7/9) is preferred in acute trauma because post-traumatic hemarthrosis provides natural joint distention, making arthrography unnecessary 1, 2
• MRI without contrast is also appropriate when optimized imaging equipment is available 1
• CT arthrography (rating 5/9) is reserved for patients with MRI contraindications 1

When Radiographs Are Normal: Acute Trauma with Persistent Pain

• MRI without contrast is the preferred study as it identifies rotator cuff tears, bone contusions, acromioclavicular sprains, capsular tears, and occult fractures missed on radiographs 1, 2, 3
• A 2021 prospective study demonstrated MRI revealed abnormalities in all 48 patients with normal radiographs after acute shoulder trauma, establishing definitive diagnoses including 6 occult fractures, 13 rotator cuff tears, and 4 cases of instability 3
• Ultrasound has limited utility in acute trauma, with only 71% concordance with final diagnosis and 0% detection rate for instability 3

Common Pitfalls to Avoid

• Never skip initial radiographs even when soft tissue pathology is strongly suspected, as 10-15% of cases will show unexpected bony abnormalities that alter management 2, 4
• Do not obtain only a single AP view—orthogonal views are essential to avoid missing dislocations and fracture displacement 1, 2
• Avoid ordering MR arthrography in acute trauma—the natural joint effusion makes contrast injection unnecessary and potentially harmful 1, 2
• Do not rely on ultrasound alone in trauma settings—it completely misses bone contusions and instability, which are present in the majority of cases 3
• Recognize that clinical examination has only 42-52% concordance with final diagnosis in acute shoulder trauma, making imaging essential rather than optional 3