Frozen shoulder is also called adhesive capsulitis. It is a relatively common cause of shoulder pain and stiffness. The loss of range of motion and function in the shoulder joint can significantly impair activities.
It most commonly affects people in middle age. Diabetes is a key risk factor.
Adhesive capsulitis can be:
- Primary – occurring spontaneously without any trigger
- Secondary – occurring in response to trauma, surgery or immobilisation
Pathophysiology
The glenohumeral joint is the ball and socket joint in the shoulder. The glenohumeral joint is surrounded by connective tissue that forms the joint capsule.
In adhesive capsulitis, inflammation and fibrosis in the joint capsule lead to adhesions (scar tissue). The adhesions bind the capsule and cause it to tighten around the joint, restrict movement in the joint.
Presentation
There is a typical course of symptoms, with three phases:
- Painful phase – shoulder pain is often the first symptom and may be worse at night
- Stiff phase – shoulder stiffness develops and affects both active and passive movement (external rotation is the most affected) – the pain settles during this phase
- Thawing phase – there is a gradual improvement in stiffness and a return to normal
The entire illness lasts 1 – 3 years before resolving (e.g., 6 months in each phase). However, a large number of patients (up to 50%) have persistent symptoms.
Differential Diagnosis
The main differentials in a patient presenting with shoulder pain not preceded by trauma or an acute injury are:
- Supraspinatus tendinopathy
- Acromioclavicular joint arthritis
- Glenohumeral joint arthritis
Rare but important differentials to keep in mind are:
- Septic arthritis
- Inflammatory arthritis
- Malignancy (e.g., osteosarcoma or bony metastasis)
Shoulder pain preceded by trauma or an acute injury may be due to:
- Shoulder dislocation
- Fractures (e.g., proximal humerus, clavicle or rarely the scapula)
- Rotator cuff tear
Supraspinatus tendinopathy involves inflammation and irritation of the supraspinatus tendon, particularly due to impingement at the point where it passes between the humeral head and the acromion. The empty can test (AKA Jobe test) can be used to assess for supraspinatus tendinopathy. This involves the patient abducting the shoulder to 90 degrees and fully internally rotating the arm as though they are emptying a can of water. The examiner pushes down on the arm while the patient resists. The test is positive if there is pain or the arm gives way.
Acromioclavicular (AC) joint arthritis can be demonstrated on examination by:
- Tenderness to palpation of the AC joint
- Pain is worse at the extremes of the shoulder abduction, from around 170 degrees onwards when the arm is overhead
- Positive scarf test – pain caused by wrapping the arm across the chest and opposite shoulder
Diagnosis
Adhesive capsulitis is a clinical diagnosis based on the history and examination and excluding other causes of shoulder pain and stiffness. Imaging investigations are not usually required.
X-rays are usually normal. However, they are helpful for diagnosing osteoarthritis as a differential.
Ultrasound, CT or MRI scans can show a thickened joint capsule.
Management
Non-surgical options for improving symptoms and speeding up recovery are:
- Continue using the arm but don’t exacerbate the pain
- Analgesia (e.g., NSAIDs)
- Physiotherapy
- Intra-articular steroid injections
- Hydrodilation (injecting fluid into the joint to stretch the capsule)
Surgery may be used in particularly resistant or severe cases. The options are:
- Manipulation under anaesthesia – forcefully stretching the capsule to improve the range of motion
- Arthroscopy – keyhole surgery on the shoulder to cut the adhesions and release the shoulder
Last updated August 2021