Introduction
Understanding the pathophysiology of adhesive capsulitis is essential for effective physiotherapy management. Adhesive capsulitis, commonly called frozen shoulder, is characterized by progressive pain and stiffness in the shoulder joint.
The condition develops when the joint capsule of the shoulder becomes inflamed and thickened, which restricts normal movement of the glenohumeral joint. Over time, fibrosis and adhesions form within the capsule, further limiting mobility.
Because the shoulder joint normally has the greatest range of motion in the body, even small capsular changes can significantly affect function.
Anatomy of the Shoulder Capsule
The shoulder joint is surrounded by a fibrous capsule that provides stability while allowing wide movement.
This capsule includes:
- Glenohumeral ligaments
- Synovial membrane
- Capsular connective tissue
Under normal conditions, the capsule remains flexible and allows movements such as flexion, abduction, and rotation.
However, when inflammation occurs, the capsule becomes thickened and contracted. This contraction reduces joint space and restricts movement.
Inflammatory Changes in Adhesive Capsulitis
The early stage of adhesive capsulitis involves synovial inflammation. The synovial membrane becomes irritated and produces inflammatory mediators.
These inflammatory processes lead to:
- Pain during movement
- Increased capsular sensitivity
- Gradual reduction in shoulder mobility
If the inflammatory phase continues, the capsule begins to develop fibrosis and adhesions, which significantly restrict movement.
Capsular Tightening and Fibrosis
As the condition progresses, the joint capsule undergoes structural changes. Fibrous tissue gradually replaces normal elastic connective tissue.
This process results in:
- Capsular thickening
- Adhesion formation
- Reduced joint volume
Because of these changes, shoulder movements such as external rotation and abduction become severely limited.
Capsular contracture is one of the main reasons why frozen shoulder causes persistent stiffness.
Stages of Frozen Shoulder
Adhesive capsulitis usually progresses through three distinct clinical stages.
Freezing Stage
The freezing stage is the initial phase of the condition.
During this stage:
- Shoulder pain gradually increases
- Movement becomes painful
- Night pain is common
- Range of motion begins to decrease
The inflammatory process is most active during this phase.
Frozen Stage
In the frozen stage, pain may decrease slightly, but stiffness becomes the dominant problem.
Characteristics of this stage include:
- Severe limitation of shoulder movement
- Difficulty performing daily activities
- Reduced external rotation and abduction
Although pain may be less intense, functional limitations become more noticeable.
Thawing Stage
The thawing stage represents gradual recovery of shoulder mobility.
During this stage:
- Pain continues to decrease
- Shoulder movement slowly improves
- Functional activities become easier
With appropriate physiotherapy rehabilitation, many patients regain significant shoulder function.
Risk Factors for Adhesive Capsulitis
Several factors increase the risk of developing frozen shoulder.
Common risk factors include:
- Diabetes mellitus
- Prolonged shoulder immobilization
- Previous shoulder injury
- Thyroid disorders
- Age between 40 and 60 years
Understanding these risk factors helps clinicians identify high-risk patients.
Clinical Implications for Physiotherapy
Knowledge of the pathophysiology of adhesive capsulitis helps physiotherapists design appropriate treatment strategies.
Rehabilitation programs usually focus on:
- Pain management during early stages
- Gentle mobility exercises
- Progressive stretching of the capsule
- Strengthening shoulder stabilizers
Treatment should be adjusted based on the stage of the condition.
Conclusion
The pathophysiology of adhesive capsulitis involves inflammation, capsular thickening, and progressive fibrosis of the shoulder joint capsule. These structural changes lead to pain and restricted movement.
Understanding the stages of frozen shoulder allows physiotherapists to select appropriate interventions and guide patients through the recovery process.
Early rehabilitation and consistent physiotherapy exercises can significantly improve shoulder mobility and functional outcomes.