Imaging Guidelines for Acute Shoulder Trauma

Radiographic Protocol

• A standard shoulder trauma series must include at minimum three views: anteroposterior (AP) in internal and external rotation, plus either an axillary or scapula‑Y view. American College of Radiology (ACR) guideline. 1
• Axillary or scapula‑Y views are essential because glenohumeral and acromioclavicular dislocations are frequently mis‑classified on AP views alone. ACR. 2

Key Findings on Initial Radiographs

• Evaluate alignment for glenohumeral dislocation, acromioclavicular separation, or scapular malalignment. ACR. 1
• Identify fractures of the proximal humerus, clavicle, scapula, or glenoid and assess displacement and comminution. ACR. 2
• Measure glenohumeral and acromioclavicular joint spaces to detect widening. ACR. 1
• Look for soft‑tissue signs such as joint effusion or surrounding swelling. ACR. 1

Immediate Management of Displaced Injuries

• Displaced fractures or dislocations require prompt orthopedic consultation for possible acute surgical intervention. ACR. 1
• Unstable or markedly displaced fractures are not suitable for initial conservative (non‑operative) management. ACR. 1

Advanced Imaging Pathway When Radiographs Are Normal or Indeterminate

• MRI without contrast is the preferred next‑step modality; it receives a 9/9 appropriateness rating from the ACR. ACR. [2][3]

  • Detects soft‑tissue injuries (rotator‑cuff tears, labral tears, capsular and ligamentous damage). ACR. 2
  • Reveals occult fractures such as bone‑marrow contusion or nondisplaced fracture lines missed on plain films. ACR. 3
  • No intravenous contrast is needed acutely because traumatic joint effusion provides intrinsic contrast. ACR. 5
  • Superior to MR arthrography in the acute setting; the invasive arthrogram adds no diagnostic benefit when joint fluid is already present. ACR. 5

• Ultrasound (performed by experienced operators) is rated 9/9 for appropriateness and is especially useful for evaluating rotator‑cuff pathology. Clinical practice guidance. 4

  • Limitations: poor visualization of labral lesions, bone‑marrow edema, and deep intra‑articular structures. ACR. 3
  • Evidence is conflicting regarding detection of partial‑thickness rotator‑cuff tears. ACR. 6

• CT without contrast should be reserved for cases where detailed fracture characterization is required beyond plain radiographs. ACR. 2

  • CT alters clinical management in up to 41 % of proximal humerus fractures by better defining fracture morphology. ACR. 2
  • CT has virtually no role in diagnosing soft‑tissue injuries such as rotator‑cuff or labral tears. ACR. 3

Common Pitfalls to Avoid

• Relying solely on AP views leads to missed dislocations; axillary or Y views are mandatory. ACR. [1][2]
• Using CT as the first‑line advanced imaging for shoulder pain overlooks the most common causes (rotator‑cuff and labral tears). ACR. 3
• Performing MR arthrography in the acute trauma setting is unnecessary; non‑contrast MRI provides equivalent diagnostic information. ACR. 5
• Assuming normal radiographs exclude significant pathology is erroneous; soft‑tissue injuries remain the most frequent source of post‑traumatic shoulder pain despite normal X‑rays. ACR. 3

Specific Clinical Scenarios

• Positive rotator‑cuff clinical tests (e.g., empty‑can or drop‑arm) warrant MRI or ultrasound to confirm the diagnosis and to characterize tear size, retraction, muscle atrophy, and fatty infiltration, guiding the decision between conservative care and surgical repair. Clinical practice guidance. 4

• Suspected vascular compromise (e.g., possible axillary‑artery injury) – CT angiography is the preferred examination, providing both arterial mapping and high‑quality bone assessment. ACR. 6

• Prior rotator‑cuff repair with suspected re‑tear – MRI without contrast, MR arthrography, and ultrasound are all rated 9/9 for appropriateness and may be selected based on local expertise. ACR. 7