DESCRIPTION

• Adhesive capsulitis (AC) or frozen shoulder:
  • Presents as progressive painful restriction in range of movement of the glenohumeral (GH) joint
  • Course usually involves diminishment of pain but can have residual pain and limits of active and passive range of motion (ROM).
• Subtypes:
  • Primary AC:
    • Idiopathic
    • Usually associated with diabetes mellitus (DM)
    • Typically resolves in 9 to 24 months
  • Secondary AC:
    • Typically due to prolonged immobilization
    • Most commonly due to a complication of rotator cuff impingement syndrome (rotator cuff tendonitis) that remains incompletely treated
    • Sometimes called “shoulder-hand-syndrome,” which is a complex regional pain syndrome (CRPS) or reflex sympathetic dystrophy (RSD), if it is characterized by shoulder pain, diffuse swelling, and decreased ROM
• Clinical course:
  • Phase 1 (2 to 9 months): painful phase; pain is constant; diagnosis may be difficult if restricted movement is not present in early disease.
  • Phase 2 (4 to 12 months): stiffening or freezing phase; movement becomes restricted, especially with external rotation.
  • Phase 3 (12 to 42 months): resolution or thawing phase; gradual return to normal shoulder mobility

EPIDEMIOLOGY

ETIOLOGY AND PATHOPHYSIOLOGY

Underlying fundamental processes:

• Idiopathic
• Inflammation: Mast cells, T cells, B cells, and macrophages have been identified histologically, suggesting an inflammatory process. Studies confirm presence of elevated inflammatory cytokines such as IL-1, IL-6, TNF-α, COX-1, and COX-2 (1).
• Elevated markers for neoangiogenesis (CD34) and neoinnervation (GAP43, PGP9.5, NGFR/p75 NTR) have been associated with AC which helps explain the acute painful phase. Additionally, one study showed that over expression of TGF-β led to the development of AC in rats (1).
• Scarring: Fibroblasts and myofibroblasts have been identified histologically. Capsular contracture reduces the joint volume to 3 to 4 mL compared to the normal 10 to 15 mL. Intracellular adhesion molecule-1 (ICAM-1) facilitates leukocyte endothelial transmigration. It is elevated in both AC and DM.
• This scarring primarily effects the rotator interval (coracohumeral ligament [CHL], biceps tendon, and GH capsule). A contracted CHL is an essential finding in AC (1).
• Contracture of the GH capsule from loss of synovial layer, capsular adhesions, and loss of capsular volume are seen in AC.

RISK FACTORS

• Shoulder immobilization; often due to impingement syndrome (most significant risk factor)
• Increasing age
• Female gender
• DM
• Thyroid disease
• Atherosclerotic cardiovascular disease (ASCVD): cerebrovascular accident (CVA)/myocardial infarction (MI)/hyperlipidemia
• Antiretroviral medication use
• Parkinson disease
• Trauma/surgery
• Prior history of AC in contralateral shoulder

GENERAL PREVENTION

• Active lifestyle, while avoiding shoulder injury
• Control of DM, atherosclerotic disease, thyroid, and autoimmune conditions

COMMONLY ASSOCIATED CONDITIONS

DM, autoimmune disorders, Parkinson disease, highly active antiretroviral therapy (HAART) use, CVA/MI, cervical disc disease, thyroid disorders