Adhesive capsulitis of the shoulder

Adhesive capsulitis of the shoulder, also known as frozen shoulder, is a condition characterised by thickening and contraction of the shoulder joint capsule and surrounding synovium. Adhesive capsulitis can rarely affect other sites such as the ankle ⁸.

Epidemiology

The incidence in the general population is thought to be 3-5%. Adhesive capsulitis typically affects women in their 5^th to 6^th decades, although patients with co-morbidities such as diabetes mellitus may develop the condition at earlier ages. The incidence in patients with diabetes is reported to be 2 to 4 times higher than in the general population.

Clinical presentation

Adhesive capsulitis presentation can be broken into three distinct stages:

• freezing: painful stage 
  • patients may not present during this stage because they think that eventually, the pain will resolve if self-treated
  • as the symptoms progress, pain worsens and both active and passive range of motion (ROM) becomes more restricted
  • this can eventually result in the patient seeking medical consultation
  • typically lasts between 3 and 9 months and is characterised by acute synovitis of the glenohumeral joint
• frozen: transitional stage
  • most patients will progress to the second stage
  • during this stage, shoulder pain does not necessarily worsen
  • because of pain at the end of the range of motion, arm movement may be limited, causing muscular disuse
  • can last between 4 to 12 months
  • the common capsular pattern of limitation has historically been described as diminishing motions with external shoulder rotation being the most limited, followed closely by shoulder flexion, and internal rotation
  • a point is eventually reached in the frozen stage where pain does not occur at the end of the range of motion
• thawing stage
  • begins when the range of motion starts to improve
  • lasts anywhere from 12 to 42 months and is defined by a gradual return of shoulder mobility

Pathology

Adhesive capsulitis is divided into two main types: 

• primary or idiopathic
  • absence of preceding trauma
• secondary 
  • major or minor repetitive trauma
  • shoulder or thoracic surgery
  • endocrine, e.g. diabetes, hyperthyroidism ¹²
  • rheumatological conditions

Radiographic features

Fluoroscopy

Described features on fluoroscopic arthrography include:

• limited injectable fluid capacity of the glenohumeral joint 
• small dependent axillary fold
• small subscapularis bursa
• irregularity of the anterior capsular insertion at the anatomic neck of the humerus
• lymphatic filling may be present

Ultrasound

• limitation of movement of the supraspinatus is considered a sensitive feature ⁷
• limited external rotation, identified when positioning for subscapularis tendon assessment
• thickened coracohumeral ligament (CHL) can be suggestive ⁹
• thickening of the inferior glenohumeral capsule ¹⁶
• echogenic material around the long head of biceps at rotator interval
• increased vascularity of long head of biceps at rotator interval ¹³

MRI/MR arthrography

• normal inferior glenohumeral ligament measures <4 mm and is best seen on coronal oblique images at the mid glenoid level; in adhesive capsulitis, the axillary recess may show thickening ≥1.3 cm^ref
• T2 hyperintensity of the inferior glenohumeral ligament ¹⁷
• joint capsule thickening ²
  • anterior capsule thickness >3.5 mm and abnormal hyperintensity ¹⁴
• abnormal soft tissue thickening within the rotator interval with signal alteration¹⁸
• abnormal soft tissue encasing the biceps anchor¹⁸
• variable degree enhancement of the capsule and synovium within the axillary recess and rotator interval¹⁸

Other MR arthrography features include:

• thickening of the coracohumeral ligament (CHL) ⁴
• subcoracoid triangle sign ⁴

Chronic frozen shoulder may show low T2 signal and pericapsular scarring ¹⁵. 

Treatment and prognosis

Adhesive capsulitis is typically a self-limiting disease that improves over 1-2 years. Treatment options include:

• physiotherapy
• corticosteroid injections
• glenohumeral hydrodilatation
• closed manipulation under anaesthesia
• arthroscopic capsular release with lysis of adhesions