What is the differential diagnosis for shoulder cramping?

Differential Diagnosis for Shoulder Cramping

The differential diagnosis for shoulder cramping must be systematically approached based on patient age, mechanism of injury, and red flag symptoms, with rotator cuff disease being the predominant cause in patients over 35-40 years, while younger patients require evaluation for instability and labral pathology. 1

Age-Stratified Differential Approach

Patients Over 35-40 Years

The primary diagnostic considerations in this age group include:

• 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: Characterized by pain with overhead activities, narrowing of subacromial space, and positive impingement signs 1
• Glenohumeral osteoarthritis: Progressive condition with pain, decreased range of motion, and crepitus 1
• Acromioclavicular joint arthritis: Superior shoulder pain, tenderness over the AC joint, and pain with cross-body adduction 1
• Adhesive capsulitis (frozen shoulder): Progressive stiffness with global loss of passive and active range of motion 1

Patients Under 35 Years

Primary considerations shift to:

• Glenohumeral instability: History of dislocation or subluxation events with positive apprehension and relocation tests 1, 2
• Labral tears: Require evaluation with MR arthrography as the reference standard, with 86-100% sensitivity for detection 3
• Sports-related injuries: Including SLAP lesions and internal impingement 1

Traumatic vs. Atraumatic Presentations

Acute Traumatic Causes

When trauma is present, consider:

• Fractures: Proximal humerus, clavicle, scapula, or glenoid fractures—assess mechanism, height of fall, and landing position 1
• Glenohumeral dislocation: Anterior, posterior, or inferior with visible deformity, severe pain, and inability to move the shoulder 1
• Acromioclavicular separation: Direct blow to shoulder with visible step-off deformity and tenderness over AC joint 1
• Bankart lesion: Anterior labral tear with or without bony fragment, associated with anterior dislocation 1
• Hill-Sachs lesion: Posterolateral humeral head compression fracture from anterior dislocation 1
• Acute rotator cuff tear: Particularly in patients over 40 years following fall or trauma 1

Atraumatic Causes

• Rotator cuff tendinopathy: Chronic degenerative process without focal disruption 4
• Subacromial bursitis or long head of biceps tenosynovitis: Best evaluated with MRI or ultrasound 4
• Crystalline arthropathy: Gout or pseudogout affecting the glenohumeral joint 1

Red Flag Diagnoses Requiring Urgent Evaluation

These conditions require immediate recognition and expedited management:

• Septic arthritis: Medical emergency with fever, severe pain, warmth, erythema, and constitutional symptoms—requires urgent arthrocentesis under ultrasound or fluoroscopic guidance 4, 1
• Osteomyelitis: Persistent pain, fever, and elevated inflammatory markers 1
• Malignancy: Primary bone tumor or metastatic disease with unexplained weight loss, night pain, and risk of pathologic fracture 1
• Massive rotator cuff tear: Acute complete tear requiring expedited repair for optimal outcomes 1

Systemic Conditions Presenting as Shoulder Pain

• Avascular necrosis: Particularly in patients with history of corticosteroid use, alcohol abuse, or sickle cell disease 1
• Adhesive capsulitis: Can be associated with diabetes and thyroid disorders 2

Critical Diagnostic Pitfalls to Avoid

Common errors that lead to missed or delayed diagnoses:

• Assuming absence of trauma excludes fracture: Osteoporotic fractures can occur with minimal or unrecognized trauma in elderly patients 1
• Relying on AP views alone: Scapular Y or axillary views are essential to avoid missing acromioclavicular or glenohumeral dislocations 1
• Failing to assess scapular dyskinesis: Poor scapular mechanics both contribute to and result from rotator cuff pathology 1
• Overlooking referred pain: Cervical spine pathology, cardiac ischemia, and diaphragmatic irritation can all present as shoulder pain 2

Initial Diagnostic Workup

Start with plain radiographs including AP views in internal and external rotation plus axillary or scapular Y view 4, 3

When Radiographs Are Noncontributory:

For patients over 35-40 years with suspected rotator cuff disease:

• MRI shoulder without contrast (rating 9/9) or ultrasound (rating 9/9) are equivalent for evaluating rotator cuff and biceps pathology 4

For patients under 35 years with suspected labral tear or instability:

• MR arthrography (rating 9/9) is preferred for chronic symptoms 4, 3
• MRI without contrast (rating 9/9) is preferred for acute dislocation when joint effusion is present 3

For suspected septic arthritis:

• Ultrasound or fluoroscopic-guided arthrocentesis (both rating 9/9) is the procedure of choice 4