What is the differential diagnosis for a patient presenting with shoulder pain?

Differential Diagnosis for Shoulder Pain

Age-Based Diagnostic Framework

In patients over 35-40 years, rotator cuff disease, degenerative changes, and arthritis are the predominant causes of shoulder pain, while patients under 35 years should be evaluated primarily for instability, labral tears, and sports-related injuries. 1

Patients Over 35-40 Years

Primary diagnoses to consider:

• Rotator cuff tendinopathy or tear - presents with pain during overhead activities, weakness with abduction and external rotation, and positive empty can test 1
• Subacromial impingement syndrome - pain with overhead activities, narrowing of subacromial space, positive impingement signs 2
• Glenohumeral osteoarthritis - progressive pain, decreased range of motion, crepitus 3
• Acromioclavicular joint arthritis - superior shoulder pain, tenderness over AC joint, pain with cross-body adduction 2
• Adhesive capsulitis (frozen shoulder) - progressive stiffness, global loss of passive and active range of motion 3
• Calcific tendinitis - acute severe pain, visible calcification on radiographs 4

Patients Under 35 Years

Primary diagnoses to consider:

• Glenohumeral instability - history of dislocation or subluxation, sensation of shoulder "giving way," positive apprehension test 1
• Labral tears (including SLAP lesions) - pain with overhead activities, clicking or catching sensation, positive O'Brien's test 3
• Traumatic rotator cuff injury - acute onset after specific trauma, weakness with resisted movements 3

Traumatic vs. Atraumatic Presentations

Traumatic Shoulder Pain (Specific Injury Event)

Immediate considerations:

• Fractures - proximal humerus, clavicle, scapula, or glenoid fractures; assess mechanism, height of fall, landing position 1
• Glenohumeral dislocation - anterior (95%), posterior, or inferior; visible deformity, severe pain, inability to move shoulder 3
• Acromioclavicular separation - direct blow to shoulder, visible step-off deformity, tenderness over AC joint 3
• Bankart lesion - anterior labral tear with or without bony fragment, associated with anterior dislocation 3
• Hill-Sachs lesion - posterolateral humeral head compression fracture from anterior dislocation 3
• Rotator cuff tear - acute tear from fall or trauma, particularly in patients over 40 years 3

Atraumatic Shoulder Pain (No Specific Injury)

Primary considerations:

• Rotator cuff tendinopathy - gradual onset, repetitive overhead activities, eccentric loading during deceleration phase 1
• Subacromial bursitis - inflammation of bursa, pain with overhead activities 4
• Biceps tendinitis - anterior shoulder pain, tenderness in bicipital groove, positive Speed's or Yergason's test 3
• Scapular dyskinesis - abnormal scapular movement patterns contributing to impingement 1

Pain Location-Specific Differential

Anterior Shoulder Pain

• Rotator cuff pathology - supraspinatus or subscapularis involvement 1
• Biceps tendinitis or tear - pain in bicipital groove, may have visible "Popeye" deformity if ruptured 3
• Glenohumeral joint pathology - arthritis, labral tears, capsulitis 4

Superior Shoulder Pain

• Acromioclavicular joint disease - arthritis, separation, osteolysis 1
• Supraspinatus tendinopathy - pain at top of shoulder with overhead activities 2

Posterior/Scapular Pain

• Cervical radiculopathy - referred pain from C5-C6 nerve roots, associated neck pain, neurological symptoms 1
• Infraspinatus or teres minor pathology - posterior rotator cuff involvement 3
• Scapulothoracic disorders - snapping scapula, muscle strain 5

Red Flag Diagnoses Requiring Urgent Evaluation

These conditions require immediate specialist referral:

• Septic arthritis - fever, severe pain, warmth, erythema, constitutional symptoms; requires urgent arthrocentesis 3, 6
• Osteomyelitis - persistent pain, fever, elevated inflammatory markers 3
• Malignancy - primary bone tumor or metastatic disease; unexplained weight loss, night pain, pathologic fracture 3
• Pancoast tumor - lung apex tumor causing shoulder pain via brachial plexus invasion 7
• Acute vascular compromise - thoracic outlet syndrome with vascular occlusion, subclavian artery stenosis 7
• Massive rotator cuff tear - acute complete tear requiring expedited repair for optimal outcomes 6

Referred Pain Sources

Always consider extra-articular sources:

• Cervical spine pathology - radiculopathy, disc herniation, stenosis; pain radiates down arm with numbness/tingling 1, 7
• Brachial plexus compression - thoracic outlet syndrome; symptoms with arm elevation, vascular changes 7
• Cardiac ischemia - left shoulder pain with chest discomfort, dyspnea, diaphoresis 7
• Diaphragmatic irritation - subphrenic abscess, splenic pathology, gallbladder disease via phrenic nerve (C3-C5) 7
• Pulmonary pathology - pneumonia, pleural effusion, lung cancer causing referred shoulder pain 7

Systemic Conditions Presenting as Shoulder Pain

• Rheumatoid arthritis - bilateral shoulder involvement, morning stiffness, other joint involvement 8
• Polymyalgia rheumatica - bilateral shoulder and hip girdle pain in patients over 50 years, elevated ESR 8
• Crystalline arthropathy - gout or pseudogout affecting glenohumeral joint 3
• Avascular necrosis - history of corticosteroid use, alcohol abuse, sickle cell disease 3

Common Diagnostic Pitfalls

Critical errors to avoid:

• Assuming absence of trauma excludes fracture - osteoporotic fractures occur with minimal or unrecognized trauma in elderly patients 1
• Missing acromioclavicular or glenohumeral dislocations on AP views alone - scapular Y or axillary views are essential 3
• Attributing all shoulder pain to rotator cuff in older patients - always consider referred pain from cervical spine or visceral sources 7
• Failing to assess for scapular dyskinesis - poor scapular mechanics contribute to and result from rotator cuff pathology 1
• Overlooking bilateral symptoms - suggests systemic inflammatory condition rather than mechanical pathology 8
• Not correlating imaging findings with clinical symptoms - asymptomatic rotator cuff tears and degenerative changes are common; treat the patient, not the images 4