Adhesive capsulitis of shoulder

Alternate names

• Frozen shoulder

Definition

• Adhesive capsulitis (AC), is also known as frozen shoulder an insidious painful condition of the shoulder persisting more than 3 months. This inflammatory condition that causes fibrosis of the glenohumeral joint capsule is accompanied by gradually progressive stiffness and significant restriction of range of motion (typically external rotation).

Etiology

The etiology of frozen shoulder is not yet fully understood. However, some plausible risk factors have been identified:

• Diabetes Mellitus (with a prevalence up to 20%)
• Stroke
• Thyroid disorder
• Shoulder injury
• Dupuytren disease
• Parkinson's Disease
• Cancer
• Complex regional pain syndrome

Epidemiology

• Adhesive capsulitis occurs in up to 5%. Females are 4 times more often affected than men, while the non-dominant shoulder is more prone to be affected.

Staging

From a practical point of view, we recommended using  2-stage scheme: early and developed frozen shoulder.

1. Freezing (2 to 9 months): Early
2. Frozen (4 to 12 months): Developed
3. Thawing (12 to 42 months): Developed

• Freezing

An initial, painful phase with predominant pain that is worse at night, with gradually increased glenohumeral joint ROM restriction.

• Frozen

The second phase with stiffness and persisted glenohumeral joint motion limitation, but with less pain than that at the “Freezing” stage.

• Thawing

The third (recovery) phase with the gradual return of range of motion.

Frozen shoulder

Signs and symptoms

• Patients suffering from early AC usually present with a sudden onset of unilateral anterior shoulder pain. The typical symptoms comprise passive and active range of motion restriction, first affecting external rotation and later abduction of the shoulder.
• In general, depending on the stage and severity, the condition is self-limiting, interfering with activities of daily living, work, and leisure activities.
• Functional impairments caused by frozen shoulder consist of limited reaching, particularly during overhead (e.g., hanging clothes) or to-the-side (e.g., fasten one's seat belt) activities. Patients also suffer from restricted shoulder rotations, resulting in difficulties in personal hygiene, clothing and brushing their hair.
• Another common concomitant condition with frozen shoulder is neck pain, mostly derived from overuse of cervical muscles to compensate the loss of shoulder motion.
• The most pathognomonic feature for AC is a loss of passive range of motion (ROM). Practically, in cases of significant restriction of passive ROM, an examination of active motion can be skipped.

Diagnosis

• Frozen shoulder is a clinical diagnosis made by medical history, physical examination, and imaging modalities (ruling out another condition, rather than confirming the diagnosis of AC).
• The imaging tool mostly applied to patients with AC is high-resolution musculoskeletal ultrasonography (MUS), which has emerged to be the first line to scrutinize shoulder pathology.
• A plain radiograph is of limited diagnostic values in patients with frozen shoulder. Nevertheless, it is reasonable to obtain routine shoulder radiographs to rule out other etiologies (e.g., tumors, acromioclavicular and glenohumeral osteoarthritis).
• MRI (Magnetic resonance imaging) may show thickening of the coracohumeral ligament and glenohumeral joint capsule. MRI Arthrography may show a volume reduction of the joint space.
• The “lidocaine test” is subacromial injection test that may be helpful in establishing the diagnosis in ambiguous clinical scenarios, to rule out subacromial conditions. In patients with AC, passive movement limitation persists after injection of local anesthetics into the subacromial space. On the other hand, patients suffering from subacromial impingement syndrome (e.g., pathology of the rotator cuff or bursa) usually experience improved passive range of motion after injection. The injection can easily be performed with ultrasound guidance.

Management

The majority of treatment options for AC are non-operative and include pharmacological management and physical therapy.

Early frozen shoulder:

• An early stage of AC is often managed as subacromial pathology. The early “freezing” AC mentioned above can be considered as inflammatory. On the other hand, the inflammation becomes less accentuated in the later stages, where ROM limitation is predominant, and inflammation-related pain is not as much pronounced. In the light of above differences, we must consider the disease stage when planning the treatment strategy.
• The aim of treatment in the “freezing” stage should focus on pain control, reduction of inflammation and patient education. Initial treatment options for adhesive capsulitis may include acetaminophen or NSAID.
• Physical therapy is important for pain control and restoration of normal shoulder mobility.
• The patient can be prescribed, e.g., therapeutic ultrasound, cryotherapy or transcutaneous electrical nerve stimulation (TENS) unit. Physical therapy management should focus on therapeutic exercise. Although not all patients can tolerate mobilization exercise within the initial stage of the frozen shoulder due to severe pain, a supervised therapeutic exercise should be conducted to slow down ROM restriction.

Developed frozen shoulder:

• After the inflammation-related painful period subsides, the condition progresses to a “frozen” and subsequently into a “thawing” phases. Treatment objectives in the advanced stages should focus on regaining ROM limitation. The physical therapists should provide more intensive (compared, e.g., to subacromial pathologies) mobilization exercise to restore joint mobility.
• In patients who do not respond well to non-operative treatments, a more invasive therapy should be considered. The addition of suprascapular nerve or interscalene brachial plexus blockage may result in further improvement.
• In patients with refractory cases of frozen shoulder who do not improve after 6 months of non-operative treatment, more aggressive treatments such as capsular hydrodilatation (stretching the joint capsule by the saline injectate pressure), manipulation under anesthesia (tearing of the contracted capsule), and arthroscopic capsular release (particularly in the rotator interval) can be considered.

Differential diagnosis

• Common conditions that may mimic early adhesive capsulitis:
  • Subacromial pathology and rotator cuff tendinopathy
  • Post-stroke shoulder subluxation
  • referred pain (cervical spine or malignancy, e.g., Pancoast tumor)
• Later in the course of frozen shoulder, as severe restriction of motion comes to predominate, the diagnosis becomes more apparent. However, glenohumeral joint arthritis should also be considered, which can be ruled out by free shoulder movement following lidocaine injection to the glenohumeral joint.

Prognosis

• The duration of AC is from 1 to 3.5 years with a mean of 30 months. In about 15% of patients, the contra-lateral shoulder becomes affected within 5 years.

Complications

• Residual pain
• Residual stiffness
• Fracture of the humerus
• Rupture of the biceps tendon after shoulder manipulation

References

• Kamal Mezian; Ryan Coffey; Ke-Vin Chang. Frozen shoulder[Updated Sep 3, 2020]. In StatPearls[Internet]. Available at: https://www.ncbi.nlm.nih.gov/books/NBK482162/
• Chul-Hyun Cho, Kwang-Soon Song, Beom-Soo Kim, Du Hwan Kim, and Yun-Mee Lho. Biological Aspect of Pathophysiology for Frozen Shoulder[Updated May 24,2020]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5994312/

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