What are the key steps to diagnose frozen shoulder in a patient over 40 with a history of trauma or underlying conditions like diabetes or thyroid disease?

How to Diagnose Frozen Shoulder

Frozen shoulder is diagnosed primarily through clinical evaluation demonstrating painful, restricted shoulder motion in both active and passive range of motion, particularly external rotation and abduction, lasting at least 1 month, with initial screening radiographs required to exclude other pathology. 1, 2

Clinical Diagnostic Criteria

The diagnosis is fundamentally clinical and requires:

• History of progressive painful shoulder motion loss lasting at least 1 month 2
• Physical examination documenting painful restricted shoulder motion in both active AND passive planes - this is the key distinguishing feature from rotator cuff pathology where passive motion is preserved 1, 2
• Progressive loss of passive range of motion, particularly external rotation and abduction - these are the hallmark movements affected 3

Essential History Elements

Document these specific risk factors and clinical features:

• Diabetes mellitus - significantly increases risk of developing frozen shoulder 4, 1
• Thyroid disease - significantly increases risk 4, 1
• Dyslipidemia - increases risk 1
• History of trauma or shoulder immobilization - can trigger secondary frozen shoulder 4
• Duration and progression of symptoms - typically worsening over weeks to months 2
• Age over 40 years - frozen shoulder predominantly affects this population 3

Physical Examination Findings

Perform these specific assessments:

• Passive range of motion testing - the critical diagnostic maneuver showing restriction in multiple planes, especially external rotation with arm at side and abduction 1, 2
• Active range of motion - equally restricted as passive motion, distinguishing this from rotator cuff tears where passive motion exceeds active 3
• Pain assessment - typically diffuse shoulder pain that worsens with attempted motion 2
• Cervical spine examination - to exclude referred pain from cervical pathology 2

Required Imaging

Initial screening shoulder radiographs are mandatory to exclude other conditions such as fractures, arthritis, calcific tendinitis, or tumors that can mimic frozen shoulder 1, 2. Standard views should include AP in internal rotation, AP in external rotation, and axillary or scapula-Y view 3.

Advanced Imaging Considerations

• Ultrasound and MRI should be used as adjunctive tools alongside clinical diagnosis, NOT as independent diagnostic methods 1
• Dynamic ultrasound can visualize the "frozen" movements of the glenohumeral joint during real-time assessment 5
• MRI may show capsular thickening and inflammation but is not required for diagnosis 1

Critical Diagnostic Pitfalls to Avoid

• Do not diagnose frozen shoulder based on imaging alone - it remains a clinical diagnosis requiring demonstration of restricted passive motion 1
• Do not confuse with rotator cuff pathology - rotator cuff tears show preserved passive motion with painful/weak active motion, while frozen shoulder shows equal restriction in both 3
• Do not skip radiographs - failing to obtain initial radiographs may miss fractures, arthritis, or other pathology requiring different treatment 1, 2
• Do not assume absence of trauma excludes other diagnoses - especially in elderly patients where osteoporotic fractures can occur with minimal trauma 3

Staging Considerations

While not required for diagnosis, understanding the clinical stage helps guide treatment:

• Traditional clinicopathological staging helps plan treatment at various phases, though duration varies with interventions 4
• Most patients experience gradual resolution over 12-18 months with conservative treatment 4
• Some patients may experience long-term disabilities despite the self-limiting nature 1