Pathophysiology of Adhesive Capsulitis
Adhesive capsulitis ("frozen shoulder") is primarily characterized by fibrosis and contracture of the glenohumeral joint capsule, resulting in progressive stiffness, pain, and restriction of shoulder motion that significantly impacts quality of life. 1, 2
Primary Causes and Mechanisms
- Adhesive capsulitis involves the formation of extensive scar tissue and thickening of the glenohumeral joint capsule, leading to decreased joint volume and restricted range of motion 3
- The condition progresses through inflammatory and fibrotic phases, with initial inflammation followed by the development of adhesions that limit shoulder movement 1
- Thickening of the coracohumeral ligament is a specific radiographic finding associated with adhesive capsulitis 1
Risk Factors and Associated Conditions
Adhesive capsulitis is predominantly idiopathic but has significantly increased prevalence in patients with:
Post-surgical or post-traumatic immobilization of the shoulder can trigger the development of adhesive capsulitis 2
Clinical Presentation and Progression
The condition typically presents with an insidious onset of shoulder pain that progresses to severe limitation of movement 2
Traditionally described as progressing through three clinical phases:
- Painful phase (severe pain with initial limitation of movement)
- Freezing phase (decreasing pain but increasing stiffness)
- Thawing phase (gradual improvement in range of motion) 4
External rotation of the shoulder is most commonly and severely affected 1
The condition was previously thought to be self-limiting with complete resolution within 1-2 years, but recent evidence shows persistent functional limitations may occur if left untreated 1
Diagnostic Features
- Diagnosis is primarily clinical, based on history of progressive shoulder pain and stiffness 1
- MRI findings of coracohumeral ligament thickening are highly specific for adhesive capsulitis 1
- Bone scintigraphy demonstrates increased activity in adhesive capsulitis 5
- Radiographs are typically normal but help rule out other conditions 4
Complications and Impact
- Adhesive capsulitis can delay rehabilitation and functional recovery in stroke patients 5
- The condition may contribute to depression, sleeplessness, and reduced quality of life 6
- Without appropriate treatment, patients may experience persistent functional limitations 1
Differential Diagnosis
- Rotator cuff tendinopathy or tear
- Glenohumeral osteoarthritis
- Acromioclavicular arthropathy
- Biceps tendinopathy
- Subacromial and subdeltoid bursitis
- Autoimmune conditions (e.g., systemic lupus erythematosus, rheumatoid arthritis)
- Neoplasm 4
Understanding the pathophysiology of adhesive capsulitis is essential for appropriate management, as treatment approaches should target both the inflammatory and fibrotic components of the disease process to effectively restore shoulder function and reduce pain.