What clinical assessment and investigations are required to diagnose adhesive capsulitis (frozen shoulder)?

Clinical Assessment for Adhesive Capsulitis

Adhesive capsulitis is diagnosed primarily through clinical examination demonstrating equal restriction of both active and passive range of motion in all planes, with external rotation being the most severely affected, followed by abduction. 1

Key Diagnostic Clinical Features

Essential Range of Motion Findings

• Global restriction of both active AND passive motion in all directions is the hallmark finding that distinguishes adhesive capsulitis from other shoulder pathology 1, 2
• External (lateral) rotation is the most severely restricted movement and correlates most significantly with the onset of shoulder pain 3, 1
• Abduction is severely limited, particularly in the frozen stage 4
• Pain occurs at end-range in all directions of movement 2

Pain Characteristics to Assess

• Strong component of night pain that disrupts sleep 2
• Pain with rapid or unguarded movements 2
• Discomfort lying on the affected shoulder 2
• Pain easily aggravated by any shoulder movement 2

Patient Demographics

• Age greater than 35 years at onset (peak incidence 40-65 years) 5, 2
• More common in middle-aged women 5, 6

Critical Differential Diagnosis

You must actively exclude other conditions that can mimic adhesive capsulitis before confirming the diagnosis. 1, 4

Distinguishing from Rotator Cuff Syndrome

• Rotator cuff pathology shows preserved passive motion with weakness and pain primarily during active movement 1
• Rotator cuff syndrome demonstrates focal weakness during abduction with external or internal rotation, but passive motion remains relatively preserved 1
• In contrast, adhesive capsulitis shows equal restriction of active and passive motion 1

Other Conditions to Exclude

• Degenerative joint disease/osteoarthritis of the shoulder 4, 6
• Calcific tendinitis 6, 7
• Crystal arthropathies 4
• Septic arthritis 4
• Acromioclavicular joint disease 1
• Subacromial/subdeltoid bursitis 1, 7
• Rotator cuff tears 3, 7

Imaging Investigations

Initial Imaging

Plain radiographs are the first-line imaging study to exclude common differential diagnoses such as osteoarthritis, calcific tendinitis, and fractures 6, 7

Advanced Imaging When Radiographs Are Noncontributory

MRI without contrast is the preferred advanced imaging modality with a rating of 9 (usually appropriate) for evaluating adhesive capsulitis 1

Specific MRI Findings to Confirm Diagnosis

• Thickening of the joint capsule (particularly in the rotator interval and axillary recess) 4, 7
• Thickening of the coracohumeral ligament 7
• Fibrosis of the subcoracoid fat triangle 7
• Capsular enhancement with intravenous gadolinium increases diagnostic sensitivity 6, 7

Alternative Imaging Options

• High-resolution ultrasound can be used as a complementary diagnostic modality or alternative when MRI is contraindicated 6, 7
• Bone scintigraphy demonstrates increased periarticular activity in adhesive capsulitis, though it has poor anatomic localization 3, 4
• CT has no role in diagnosis due to radiation exposure and significantly lower sensitivity/specificity compared to MRI 6

Clinical Staging Assessment

Document which of the three progressive stages the patient is in, as this guides treatment 6, 8:

1. Freezing phase (painful stage): Progressive pain with increasing stiffness 6, 8
2. Frozen phase (adhesive stage): Severe stiffness with plateau of pain 6, 8
3. Thawing phase: Gradual improvement in range of motion 6, 8

Common Pitfalls to Avoid

• Do not rely solely on clinical examination without imaging to exclude other pathology, as clinical findings can overlap significantly with other shoulder disorders 7, 2
• Do not assume all restricted shoulder motion is adhesive capsulitis in patients under 40 years of age, as this condition rarely occurs in this population 5
• Assess for specific risk factors including diabetes, thyroid disease, recent shoulder surgery/immobilization, stroke with hemiplegia, and polyarticular osteoarthritis 3, 5
• In post-stroke patients, up to 67% with combined motor, sensory, and visuoperceptual deficits may develop shoulder-hand-pain syndrome contributing to capsulitis 3, 4