Will a shoulder X‑ray reveal rotator cuff tendinopathy or differentiate it from subacromial impingement?

Shoulder X-rays Have Limited Value for Rotator Cuff Tendinopathy and Impingement

Shoulder X-rays will NOT directly visualize rotator cuff tendinopathy or soft tissue impingement, but they can identify bony abnormalities that predispose to or result from these conditions. For definitive diagnosis of rotator cuff tendinopathy versus impingement, you need MRI or ultrasound 1.

What X-rays CAN Show

X-rays serve as an appropriate initial screening tool but have significant limitations:

Bony changes that suggest chronic impingement:

• Subacromial spurs and anterior acromial osteophytes
• Sclerosis and flattening of the greater tuberosity
• Abnormal acromial morphology (hooked or curved acromion)
• Acromioclavicular joint protrusion or arthropathy
• Decreased acromiohumeral distance 1

Special views for impingement assessment:

• Rockwood view (30° caudad angulation) or suprascapular outlet view to profile the anterior acromion 1
• Standard trauma series should include at least 3 views with 2 orthogonal projections 1

What X-rays CANNOT Show

X-rays are rated as "usually not appropriate" (rating 1-3) for evaluating:

• Rotator cuff tendinopathy or tendinosis
• Partial-thickness or full-thickness rotator cuff tears
• Subacromial bursitis
• Biceps tenosynovitis
• Soft tissue impingement 1

The Appropriate Next Step

When X-rays are noncontributory and you suspect rotator cuff pathology:

MRI without contrast (rating 9) or ultrasound (rating 9) are the appropriate next studies 1. Both modalities are considered equivalent for evaluating:

• Tendinopathy versus tendinosis (signal abnormality without tear)
• Partial-thickness tears
• Full-thickness tears
• Subacromial bursal inflammation

MRI advantages:

• Directly visualizes tendon signal abnormalities indicating tendinopathy (increased T1 and T2 signal without focal disruption) 1
• Identifies osseous lesions contributing to impingement (acromial morphology, AC joint abnormalities) 1
• High sensitivity and specificity for full-thickness tears
• Better for partial-thickness tears than ultrasound 1

Ultrasound advantages:

• Equivalent to MRI for full-thickness tears 1
• Can be performed with therapeutic injection if indicated 1
• Operator-dependent with high interobserver variability 2

Important Clinical Caveat

The radiographic measurements of subacromial distance (acromial index, lateral acromial angle, etc.) do NOT reliably correlate with the severity of impingement or predict rotator cuff tears 3. While certain acromial morphologies (larger acromial slope, smaller lateral acromial angle) may predispose to specific tear patterns 4, these measurements lack sufficient clinical significance as predictive markers 3.

Bottom Line Algorithm

1. Start with X-rays to exclude fracture, dislocation, calcific tendinitis, and identify bony impingement features
2. If X-rays are noncontributory and clinical suspicion remains for rotator cuff tendinopathy or impingement → proceed directly to MRI or ultrasound (not more X-rays)
3. MRI is preferred if you need comprehensive soft tissue evaluation or if ultrasound expertise is unavailable 1
4. Fluoroscopic arthrography is obsolete except when MRI is contraindicated and ultrasound expertise unavailable 1