frozen shoulder

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

Epidemiology

The incidence in the general population is thought to be 3-5%. Adhesive capsulitis typically affects women in their 5 to 6 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 characterized 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 
    • 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
  • limited external rotation, identified when positioning for subscapularis tendon assessment
  • thickened coracohumeral ligament (CHL) can be suggestive
  • echogenic material around the long head of biceps at rotator interval
  • increased vascularity of long head of biceps at rotator interval
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
  • joint capsule thickening
    • anterior capsule thickness >3.5 mm and abnormal hyperintensity
  • abnormal soft tissue thickening within the rotator interval with signal alteration
  • abnormal soft tissue encasing the biceps anchor
  • variable enhancement of the capsule and synovium within the axillary recess and rotator interval

Other MR arthrography features include:

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

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 anesthesia
  • arthroscopic capsular release with lysis of adhesions