What are the recommended steps to diagnose frozen shoulder in a 40-60 year old woman with a history of trauma, diabetes, or other underlying conditions, presenting with shoulder pain and limited mobility?

Diagnosing Frozen Shoulder

Frozen shoulder is diagnosed primarily through clinical assessment demonstrating painful restriction of both active and passive shoulder range of motion in all planes, particularly external rotation, without radiographic evidence of alternative pathology. 1, 2

Clinical Diagnostic Criteria

The diagnosis requires:

• Progressive painful shoulder motion loss of at least 1 month duration 3
• Restriction of both active AND passive range of motion - this distinguishes frozen shoulder from rotator cuff pathology where passive motion is typically preserved 1, 2
• External rotation is characteristically the most restricted movement, followed by abduction and internal rotation 1

Essential History Elements

Specifically assess for:

• Diabetes mellitus - significantly increases frozen shoulder risk and should always be investigated 4, 2
• Thyroid dysfunction - another major risk factor requiring investigation 4, 2
• Dyslipidemia - increases risk of developing frozen shoulder 2
• Prior shoulder trauma or surgery - distinguishes secondary from primary frozen shoulder 1
• Duration and progression of symptoms - helps determine clinical stage 1

Physical Examination Findings

Document the following:

• Painful restriction in all planes of motion - both active and passive 1, 3
• External rotation loss is the hallmark finding - typically most severely affected 1
• Cervical spine examination - to exclude referred pain 3
• Provocative testing - to differentiate from other shoulder pathology 3

Imaging Approach

Initial screening shoulder radiographs are required to exclude other conditions such as fractures, arthritis, or calcific tendinitis, but radiographs are typically normal in frozen shoulder. 3, 2

Advanced imaging considerations:

• Ultrasound and MRI should be used as adjunctive tools alongside clinical diagnosis, NOT as independent diagnostic methods 2
• MRI may show capsular thickening and synovitis but is not necessary for diagnosis in typical presentations 2
• Imaging is most useful to rule out alternative diagnoses rather than to confirm frozen shoulder 2

Clinical Staging

Recognize the three distinct stages to guide treatment:

• Stage 1 ("Freezing", 0-4 months): Progressive loss of passive motion with worsening pain 1
• Stage 2 ("Frozen", 4-8 months): Continued stiffness with improvement in pain and inflammation 1
• Stage 3 ("Thawing", 8-24 months): Gradual return of range of motion 1

Common Diagnostic Pitfalls

Avoid misdiagnosing rotator cuff tears as frozen shoulder - rotator cuff pathology typically preserves passive range of motion while frozen shoulder restricts both active and passive motion equally. 1, 3

Do not rely solely on imaging for diagnosis - frozen shoulder is a clinical diagnosis, and imaging serves primarily to exclude other pathology. 2

Always screen for diabetes and thyroid disease in patients presenting with primary frozen shoulder, as these conditions are strongly associated and may require management. 4, 2