What is Frozen Shoulder (Adhesive Capsulitis)?
Frozen shoulder, also known as adhesive capsulitis, is a common and painful shoulder disorder characterized by spontaneous onset of progressive pain and marked restriction in glenohumeral joint range of motion, particularly external rotation. 1, 2
Pathophysiology
The condition follows a well-understood pathological sequence 1:
- Synovial inflammation occurs first, followed by capsular fibrosis 1
- The coracohumeral ligament thickens, which can be detected on imaging 2
- Despite understanding the pathological process, the underlying cause remains unknown 1
Clinical Presentation
The disease progresses through three distinct phases 1, 3:
- Freezing phase (painful): Gradual increase in pain with progressive loss of motion 1, 3
- Frozen phase (adhesive): Persistent stiffness with plateau of restricted range of motion 3
- Thawing phase: Gradual recovery of motion 3
Range of motion is restricted in all planes, with external rotation being the most severely affected. 2
Clinical Impact
Adhesive capsulitis significantly affects patient quality of life 4, 5:
- Can contribute to depression and sleep disturbances 5
- Causes substantial functional disability 1
- In stroke patients specifically, it delays rehabilitation and functional recovery because the painful joint masks motor function improvement and limits use of assistive devices like canes or wheelchairs 6, 4
Diagnostic Considerations
Imaging is not necessary to make the diagnosis, which is primarily clinical 2. However, when imaging is performed:
- Bone scintigraphy demonstrates increased radiotracer activity in the affected shoulder 6, 4, 5
- Coracohumeral ligament thickening on MRI yields high specificity for adhesive capsulitis 2
Natural History
Recent evidence challenges the traditional belief that frozen shoulder fully resolves without treatment. 2 While historically thought to be self-limiting over one to two years with complete resolution 2, 3, current evidence demonstrates persistent functional limitations if left untreated 2. This finding emphasizes the importance of active treatment rather than watchful waiting.
Common Pitfalls
- Early identification is critical, particularly in high-risk populations such as breast cancer patients, where early treatment may prevent unnecessary interruptions in exercise programming 5
- The condition is often underdiagnosed or misdiagnosed as other shoulder pathologies, delaying appropriate treatment 7
- Practitioners must distinguish adhesive capsulitis from other causes of shoulder pain including rotator cuff tears, labral injuries, bursitis/tendonitis, and complex regional pain syndrome 6