When to Order X-ray and Ultrasound for Shoulder Pain
Radiography (X-ray) should be the initial imaging study for all patients presenting with shoulder pain, regardless of whether the pain is traumatic or atraumatic in origin. 1, 2
Initial Imaging: X-ray First
Order X-ray as the first-line imaging modality for any patient with shoulder pain to evaluate for fractures, dislocations, arthritis, calcifications, and bone alignment 1, 2
The standard X-ray series must include at minimum 3 views: anteroposterior (AP) views in internal and external rotation, plus either an axillary or scapular Y view 1, 2
The axillary or scapular Y view is mandatory, not optional—glenohumeral and acromioclavicular dislocations are frequently misclassified on AP views alone, and posterior dislocations are missed in over 60% of cases without orthogonal imaging 1, 3
Perform radiographs upright whenever possible, as shoulder malalignment can be underrepresented on supine imaging 1, 3
When to Order Ultrasound After X-ray
Ultrasound becomes appropriate only after X-rays have been obtained and in specific clinical scenarios:
Ultrasound is Usually Appropriate (Rating 9/9) for:
Suspected rotator cuff pathology when radiographs are noncontributory—ultrasound and MRI are considered equivalent for this indication 1, 2
Suspected bursitis or biceps tenosynovitis when radiographs are noncontributory—ultrasound and MRI are rated equally appropriate 1
Suspected septic arthritis requiring arthrocentesis—ultrasound guidance for joint aspiration is rated 9/9 2
Ultrasound is Usually NOT Appropriate (Rating 1/9) for:
Suspected labral tears or instability in patients under 35 years—MR arthrography is the gold standard (rated 9/9), while ultrasound is rated 1/9 1, 2
Acute shoulder pain that cannot be localized to the rotator cuff or biceps tendon—ultrasound has limited usefulness in evaluating bone and intra-articular pathology 1
Initial evaluation before X-ray has been performed—this violates the established imaging algorithm 1, 2, 4
Critical Algorithm for Imaging Selection
Step 1: Order X-ray (3+ views including axillary or Y view) for ALL shoulder pain 1, 2
Step 2: If X-ray shows fracture or dislocation → manage accordingly or order CT for surgical planning 1
Step 3: If X-ray is noncontributory, next imaging depends on clinical suspicion:
- Rotator cuff tear or bursitis → Ultrasound OR MRI (equivalent, choose based on local expertise) 1, 2
- Labral tear/instability (age <35) → MR arthrography (NOT ultrasound) 1, 2
- Persistent pain, unclear etiology → MRI without contrast 1, 2
- Suspected infection → Ultrasound-guided aspiration 2
Common Pitfalls to Avoid
Never order ultrasound before X-ray—this is a fundamental error that can miss fractures, dislocations, and calcifications that alter management 1, 2, 4
Never rely on AP views alone—axillary or Y views are essential to avoid missing dislocations 1, 3
Do not order ultrasound for labral pathology or instability—it is rated as "usually not appropriate" (1/9) for these indications, while MR arthrography is rated 9/9 1, 2
Recognize ultrasound's limitations—it cannot adequately evaluate bone, intra-articular structures beyond the rotator cuff, or complex fracture patterns 1
When Local Ultrasound Expertise Matters
The American College of Radiology guidelines explicitly state that ultrasound for rotator cuff and bursal pathology is rated 9/9 "if local expertise available" 1, 2. Without experienced operators, MRI becomes the preferred alternative even though both modalities are theoretically equivalent for these specific indications.