What clinical signs and symptoms should I assess to differentiate between a rotator cuff injury and other causes of shoulder pain?

To differentiate a rotator cuff injury from other causes of shoulder pain, assess the following clinical signs and symptoms:

• History of trauma with pain and weakness or sudden loss of active arm elevation suggests an acute rotator cuff tear and requires urgent referral ¹.
• Painful arc of abduction (typically between 60 and 120 degrees) and pain on abduction with the thumb down are characteristic of rotator cuff disorders ¹.
• Tenderness over the rotator cuff tendons and subacromial area supports rotator cuff pathology (Lewis et al., 2015).
• Reduced passive external rotation points more towards glenohumeral joint disorders such as frozen shoulder or arthritis rather than rotator cuff injury ¹.
• Localized pain and tenderness over the acromioclavicular (AC) joint, high arc pain, or a positive cross-arm test indicate AC joint disease rather than rotator cuff injury ¹.
• History of shoulder instability or episodes of dislocation suggests instability disorders rather than rotator cuff pathology ¹.
• Systemic signs such as fever, red skin, or being systemically unwell raise suspicion of septic arthritis or inflammatory arthritis, not rotator cuff injury ¹.
• Neurological signs such as unexplained muscle wasting or significant motor/sensory deficits suggest neurological lesions rather than rotator cuff injury ¹.
• Clinical examination should include assessment of active and passive range of motion, strength testing (notably abduction and external rotation), and special tests such as the painful arc test and impingement signs to help differentiate rotator cuff tendinopathy from other shoulder pathologies (Clarnette and Miniaci, 1998; Lewis et al., 2015).

In summary, rotator cuff injury is most likely when there is pain and weakness on active arm elevation, a painful arc, and tenderness over the rotator cuff, especially following trauma. Other causes such as AC joint disease, glenohumeral arthritis, instability, infection, or neurological lesions have distinct clinical features that should be assessed to guide diagnosis and management ¹ (Clarnette and Miniaci, 1998; Lewis et al., 2015).