Capsulite

Capsulite, or capsulitis, is inflammation of a joint capsule. The most common form is adhesive capsulitis of the shoulder, also called frozen shoulder. Inflammation leads to thickening and contracture of the capsule around the joint, producing pain and progressive restriction of both active and passive motion.

Causes and risk factors: In many cases the cause is unknown (idiopathic). It can follow shoulder injury, immobilization after surgery, or other shoulder pathology. Conditions such as diabetes mellitus, thyroid disease, and autoimmune disorders increase risk. It is more common in middle-aged adults and in women.

Pathophysiology: The condition typically evolves through stages: an initial painful (freezing) stage with increasing pain, a stiff (frozen) stage with marked ROM limitation, and a thawing stage with gradual improvement. Histologically, synovitis and capsular fibrosis with adhesions limit joint movement.

Clinical features: Patients report gradual shoulder pain, worse at night, with stiffness that restricts both passive and active movement. External rotation and abduction are particularly affected.

Diagnosis: Diagnosis is clinical. Imaging is used to rule out other problems; plain radiographs exclude arthritis; ultrasound or MRI can assess the rotator cuff and detect effusion or thickened capsule. Blood tests are not diagnostic but may be performed if an alternative diagnosis is suspected.

Management: Initial treatment is conservative, including physical therapy focused on ROM, pain control with NSAIDs, and corticosteroid injections into the capsule. Hydrodilatation and certain distension techniques may be used. In refractory cases, manipulation under anesthesia or arthroscopic capsular release may be considered.

Prognosis: Many patients improve within months to a few years, though recovery is slower in diabetes and some residual stiffness may persist.

Epidemiology: It commonly affects adults aged 40–60, with higher prevalence in women and in those with diabetes.