Is frozen shoulder the same as impingement shoulder?

Frozen Shoulder vs. Shoulder Impingement: Different Conditions with Distinct Characteristics

No, frozen shoulder (adhesive capsulitis) and shoulder impingement are two distinct shoulder conditions with different pathophysiology, clinical presentations, and treatment approaches.

Key Differences Between Frozen Shoulder and Shoulder Impingement

Pathophysiology

• Frozen Shoulder: Characterized by contracture and thickening of the glenohumeral joint capsule, resulting in painful and severely limited shoulder movement in all directions 1
• Shoulder Impingement: Involves compression of the rotator cuff tendons between the humeral head and structures of the coracoacromial arch during shoulder elevation 2

Clinical Presentation

• Frozen Shoulder:

  • Progresses through three distinct phases: freezing (painful), frozen (adhesive), and thawing 1, 3
  • Characterized by global restriction of both active and passive range of motion, especially external rotation 4
  • Typically affects patients in their 40s-60s, often with no precipitating trauma 5
  • Pain is often diffuse and may be worse at night

• Shoulder Impingement:

  • Pain primarily during specific movements, especially overhead activities 2
  • Pain typically localized to anterolateral shoulder 2
  • Positive impingement signs (Hawkins test, Neer test) 6
  • Range of motion may be painful but not as globally restricted as in frozen shoulder 7

Diagnostic Findings

• Frozen Shoulder:

  • Restriction of glenohumeral joint motion, particularly in external rotation, with normal X-rays 4
  • PET/CT with 18F-FDG tracer shows increased uptake in affected shoulder regions (sensitivity 92%, specificity 93%) 7

• Shoulder Impingement:

  • May show subacromial space narrowing on imaging
  • Often associated with rotator cuff tendinopathy or tears 2
  • No significant FDG uptake on PET/CT 7

Treatment Approaches

Frozen Shoulder

1. Conservative Management:

   • Physical therapy with gentle stretching focusing on external rotation and abduction 6, 3
   • NSAIDs and acetaminophen for pain management 6
   • Intra-articular corticosteroid injections (particularly effective in the early painful phase) 1

2. Advanced Interventions (for recalcitrant cases):

   • Manipulation under anesthesia
   • Arthroscopic capsular release 1

Shoulder Impingement

1. Conservative Management:

   • Rotator cuff and scapular stabilizer strengthening 2
   • Modification of aggravating activities
   • NSAIDs and acetaminophen for pain management 6
   • Subacromial corticosteroid injections 6

2. Surgical Options (if conservative treatment fails):

   • Arthroscopic subacromial decompression 6

Important Clinical Considerations

• Frozen shoulder is often self-limiting but may take 1-3 years to resolve completely 3
• Approximately 80% of patients with shoulder pain recover completely within 3-6 months with appropriate conservative treatment 6
• Breast cancer patients are at increased risk for both conditions due to treatment-related shoulder morbidity 2
• Early identification and treatment of both conditions can prevent unnecessary functional limitations 2

When to Refer to a Specialist

• Failure to improve after 3-6 months of appropriate conservative management 6
• Suspicion of other pathology (rotator cuff tear, glenohumeral arthritis)
• Need for advanced interventions such as corticosteroid injections, manipulation, or surgical release

Remember that accurate diagnosis is crucial for appropriate management, as the treatment approaches for these two conditions differ significantly.