What diagnostic tests are recommended for adhesive capsulitis (frozen shoulder)?

Diagnosis of Adhesive Capsulitis

Adhesive capsulitis is primarily a clinical diagnosis based on characteristic findings of painful restriction of both active and passive glenohumeral motion in all planes, with imaging reserved to exclude alternative pathology rather than confirm the diagnosis. 1

Clinical Diagnosis

The diagnosis relies on identifying the hallmark clinical presentation:

• Global restriction of passive glenohumeral range of motion is the defining feature, distinguishing adhesive capsulitis from rotator cuff pathology where passive motion is typically preserved 1
• Both active and passive motion are limited in all planes, particularly external rotation which is often the most severely affected 2, 1
• Pain accompanies the stiffness, with symptoms typically progressing through three stages: freezing phase (increasing pain and stiffness), frozen phase (persistent stiffness with improving pain), and thawing phase (gradual recovery) 2

Physical Examination Tests

While the diagnosis is clinical, specific examination maneuvers have been studied:

• The Coracoid Pain Test (affected-unaffected shoulder approach) and Distension Test in Passive External Rotation showed excellent sensitivity and specificity in their original validation studies, though these require further validation 3
• However, a universal set of validated clinical diagnostic tests remains lacking, and comparison between tests is limited by heterogeneity 3

Imaging Studies

When to Image

Imaging is indicated to exclude differential diagnoses (calcific tendinitis, rotator cuff tears, glenohumeral arthritis, acromioclavicular pathology) rather than to confirm adhesive capsulitis 4, 2, 1

Radiography (Initial Study)

• Plain radiographs should be obtained first to exclude common mimics such as glenohumeral osteoarthritis, calcific tendinitis, or fractures 2
• Standard shoulder series includes AP views in internal and external rotation plus axillary or scapula-Y view 5

MRI (Most Accurate Imaging Modality)

When imaging confirmation is needed or differential diagnosis remains uncertain:

MRI with intravenous gadolinium contrast provides the highest diagnostic accuracy for adhesive capsulitis 6, 4, 2

Key MRI Features (in order of diagnostic accuracy):

1. Axillary capsular enhancement - highest sensitivity (95%) and diagnostic accuracy (area under curve 0.96), with specificity >80% 6
2. Rotator interval (RI) joint capsule thickening - second highest diagnostic accuracy 6
3. RI enhancement - sensitivity and specificity both >80% 7
4. Inferior glenohumeral ligament (IGHL) hyperintensity - sensitivity and specificity >80% 7
5. Axillary capsular thickening and hyperintensity - both show specificity >80% 6
6. Coracohumeral ligament thickening - informative but lower specificity 6, 7
7. Fat obliteration of the rotator interval - informative but lower sensitivity 6, 7

Non-contrast MRI features can be as diagnostically helpful as MR arthrography findings, making invasive arthrography unnecessary 7

Ultrasound

• Ultrasound may serve as a complementary or alternative modality when MRI is contraindicated 2
• Can assess capsular thickening and coracohumeral ligament abnormalities 4
• Less validated than MRI for diagnostic accuracy 4

Not Recommended

• CT has no role due to radiation exposure and significantly lower sensitivity/specificity compared to MRI 2
• Fluoroscopy-guided arthrography has been replaced by MRI due to its invasiveness 2

Diagnostic Algorithm

1. Clinical assessment first: Confirm global passive motion restriction in all planes
2. Obtain plain radiographs to exclude alternative diagnoses (osteoarthritis, calcific tendinitis)
3. If diagnosis remains uncertain or atypical features present: Order MRI with IV gadolinium contrast
4. Look for axillary capsular enhancement and RI capsule thickening as the most accurate MRI features 6

Common Pitfalls

• Do not rely solely on imaging - adhesive capsulitis remains fundamentally a clinical diagnosis 1
• Do not order MR arthrography - non-contrast enhanced MRI provides equivalent diagnostic information without invasiveness 7
• Do not mistake rotator cuff pathology for adhesive capsulitis - passive motion is preserved in isolated rotator cuff disease 1