What is the differential diagnosis for a patient with shoulder pain after weight lifting, considering potential overuse or repetitive strain injuries?

Differential Diagnosis for Shoulder Pain After Weight Lifting

In a patient with shoulder pain following weight lifting, the primary differential diagnoses include rotator cuff tendinopathy/partial tear, subacromial-subdeltoid bursitis, and less commonly, labral injury or acromioclavicular joint pathology. 1, 2

Primary Diagnostic Considerations

Rotator Cuff Pathology (Most Common)

• Rotator cuff tendinopathy is the most likely diagnosis in weight-lifting-related shoulder pain, as repetitive overhead activity is the most common risk factor for subacromial pain and rotator cuff conditions 2
• The spectrum ranges from tendinosis (inflammation and fibrotic changes) to partial-thickness tears to full-thickness tears 1, 2
• Key clinical findings include pain with overhead activity, weakness on empty can test and external rotation testing, positive impingement sign, and the "arc of pain" sign (most sensitive clinical finding) 3, 4
• Partial-thickness tears most commonly occur at the articular surface of the tendon, though bursal surface and intrasubstance tears also occur 1

Subacromial-Subdeltoid Bursitis

• Frequently coexists with rotator cuff tendinopathy as part of subacromial impingement/pain syndrome 5, 2
• Results from repetitive mechanical irritation during overhead lifting movements 2
• Can mimic rotator cuff tear on clinical examination but may be distinguished by ultrasound 3

Labral Tears

• Less common in pure overuse scenarios but should be considered if there was a specific traumatic event during lifting (e.g., sudden heavy load or loss of control) 1, 6
• Clicking with circumduction is highly suggestive of labral pathology 6
• More typical in patients under 35 years with instability history 1
• Positive apprehension and relocation tests support this diagnosis 4

Acromioclavicular Joint Pathology

• Presents with superior shoulder pain, acromioclavicular joint tenderness, and positive cross-body adduction test 4
• Common in weight lifters performing bench press or overhead press exercises 4

Other Considerations

• Calcific tendinitis: Can present acutely but typically has more chronic prodrome 5
• Biceps tendinopathy: Pain localized to anterior shoulder, tenderness over bicipital groove 5, 3
• Adhesive capsulitis: Presents with diffuse pain and restricted passive range of motion, but typically develops more gradually 3, 4

Clinical Assessment Approach

History Red Flags

• Document exact mechanism of injury, specific lifting activity, weight load, and whether onset was sudden or gradual 1
• Pain with overhead activity strongly suggests rotator cuff pathology 4, 2
• Clicking or catching sensations suggest labral involvement 6
• Night pain and inability to sleep on affected side are common with rotator cuff tears 3

Physical Examination Priorities

• Impingement testing (Neer and Hawkins-Kennedy signs) for rotator cuff/subacromial pathology 3, 2
• Strength testing with empty can test (supraspinatus) and external rotation against resistance (infraspinatus/teres minor) 4
• Range of motion assessment: Restricted passive motion suggests adhesive capsulitis; pain only with active motion suggests rotator cuff pathology 4
• Acromioclavicular joint palpation and cross-body adduction test 4
• O'Brien's test or crank test if labral pathology suspected 6

Imaging Algorithm

Initial Imaging

• Standard shoulder radiographs are the preferred initial diagnostic modality to exclude fracture, dislocation, or significant arthritis 1
• In acute weight-lifting injury, radiographs are usually normal but help rule out other pathology 3
• Chronic cases may show decreased acromiohumeral distance, supraspinatus atrophy, or superior humeral head migration 3

Advanced Imaging (When Indicated)

• Ultrasound or MRI without contrast are both highly appropriate (rating 9/9) for evaluating rotator cuff integrity, with >90% sensitivity and specificity 1, 3
• Choice depends on local expertise; ultrasound is operator-dependent but excellent for rotator cuff and bursal evaluation 1, 5, 3
• MR arthrography is preferred for suspected labral tears, especially in patients under 35 years, and for distinguishing partial from full-thickness rotator cuff tears 1, 6
• In chronic cases without acute effusion, MR arthrography is superior to noncontrast MRI for labral visualization 6

Critical Pitfalls to Avoid

• Do not assume chronicity means stability: Chronic rotator cuff or labral tears can cause progressive cartilage damage and secondary osteoarthritis 6
• Do not treat imaging alone: Up to 10% of rotator cuff tears are asymptomatic and show only morphologic changes; correlate clinical findings with imaging 1
• Do not inject steroids blindly: In the presence of rotator cuff tears, steroid injections require careful consideration and should be ultrasound-guided when possible 5
• Avoid chondrotoxic agents: Lidocaine and high concentrations of long-acting local anesthetics should not be injected into joints 5
• Do not order noncontrast MRI as initial advanced imaging for suspected chronic labral tears: MR arthrography provides superior visualization 6