What is the differential diagnosis and management for right shoulder pain?

Right Shoulder Pain: Differential Diagnosis and Management

Initial Mandatory Evaluation

All patients with right shoulder pain must first undergo standard radiography with at least three views (AP in internal and external rotation, plus axillary or scapular Y view) regardless of suspected etiology, as this effectively demonstrates fractures, dislocations, arthritis, AC joint pathology, and calcific tendinitis. 1, 2, 3

Primary Differential Diagnoses by Age and Presentation

Patients Over 35-40 Years

• Rotator cuff disease is the predominant cause, presenting with anterior shoulder pain worsened by overhead activities and weakness with abduction/external rotation 3, 4
• Acromioclavicular joint osteoarthritis presents with superior shoulder pain, AC joint tenderness, and positive cross-body adduction test 4
• Glenohumeral osteoarthritis presents as gradual pain and progressive loss of motion 4
• Adhesive capsulitis shows diffuse shoulder pain with restricted passive range of motion and is associated with diabetes and thyroid disorders 4, 5

Patients Under 35-40 Years

• Glenohumeral instability typically presents with history of dislocation/subluxation events and positive apprehension/relocation tests 4
• Labral tears are more common in this age group 6

Location-Specific Pain Patterns

• Anterior shoulder pain: Rotator cuff or biceps tendon pathology 3
• Superior shoulder pain: Acromioclavicular joint disease 3
• Scapular region pain: Referred pain from cervical spine or rotator cuff 3

Critical Red Flags Requiring Urgent Evaluation

Immediate Orthopedic Referral Indicated For:

• Suspected septic arthritis (perform ultrasound or X-ray guided arthrocentesis, rated 9/9) 6, 2, 3
• Neurological deficits 1, 2, 3
• Unstable or significantly displaced fractures 1, 2, 3
• Shoulder joint instability with recurrent dislocations 2, 3
• Suspected massive rotator cuff tears in younger active patients 3

Referred Pain Sources to Exclude:

• Cervical radiculopathy: Pain radiating down arm with neurological symptoms 3, 7
• Thoracic outlet syndrome: Brachial plexus compression or subclavian vessel occlusion 7
• Intrathoracic pathology: Lung neoplasms, pleural infections, or subdiaphragmatic disease referring pain through phrenic nerve 7

Advanced Imaging Algorithm (When Radiographs Noncontributory)

For Suspected Rotator Cuff Disease or Bursitis/Biceps Tenosynovitis:

• MRI without contrast (rated 9/9) or ultrasound (rated 9/9) are equivalent options depending on local expertise 6, 2
• Standard MRI is typically sufficient for patients over 35 years 2

For Suspected Instability or Labral Tears:

• MR arthrography (rated 9/9) is generally recommended for patients under 35 years, as it distends the joint and outlines labral and capsular structures 6, 2

For Fracture Characterization:

• CT scan demonstrates fracture complexity, displacement, and angulation when more preoperative information is needed 6

Conservative Management Protocol

First-Line Pain Management:

• Acetaminophen up to 4 grams daily as first-line option 3
• Topical agents (methyl salicylate, capsaicin cream, or menthol) as second-line for mild-moderate pain 3
• Intra-articular glucocorticoid injections for pain not adequately relieved by systemic medications, especially with evidence of inflammation 3

Physical Therapy Protocol:

• Range of motion exercises through stretching and mobilization focusing on external rotation and abduction 2, 3
• Scapular stabilization exercises 3
• Electrical stimulation to improve shoulder lateral rotation 2, 3
• Avoid overhead pulleys which encourage uncontrolled abduction 2

Elective Orthopedic Referral Criteria:

• Failure of 6-12 weeks of appropriate conservative treatment 3
• Progressive functional decline despite therapy 3

Common Diagnostic Pitfalls to Avoid

• Inadequate imaging with insufficient views leading to missed fracture components or underestimation of injury severity 1
• Failure to obtain orthogonal views, risking misclassification of AC and glenohumeral dislocations 1
• Delaying surgical referral when indicated, making stabilization more technically challenging 1
• Missing referred pain from cervical spine or intrathoracic sources in patients with persistent pain and no discernible musculoskeletal abnormalities 7