Painful stiffening of the shoulder, first described by Duplay in 1834,¹ and aptly labelled “frozen shoulder” by Codman,² is a common cause of shoulder pain and disability. It is estimated to affect 2–5% of the general population and 10–20% of people with diabetes, with subsequent involvement of the contralateral shoulder estimated to occur in 5–40% of affected people.^3,4 The cumulative incidence in general practice is estimated to be 2.4/1000/year (95% confidence interval 1.9 to 2.9).⁵ The condition is most common in the 5th and 6th decades and it is slightly more common among women. Based on his arthrographic findings of synovial inflammation and adhesions, the term “adhesive capsulitis” was first coined by Neviaser.⁶ These observations led to the commonly held hypothesis that inflammation of the capsule, leading to subsequent fibrosis, is responsible for the clinical features of this condition.

Patients typically present with a history of gradual onset of severe, disabling shoulder pain accompanied by progressive limitation of both active and passive glenohumeral movement.⁷ Three phases have been described: an early painful phase, usually lasting two to nine months; an intermediate stiff phase, lasting 4–12 months, during which the stiffness predominates and pain is less pronounced; and a final recovery phase lasting 5–24 months, characterised by gradual return of movement.⁷ The pain and stiffness result in severe disability, restricting activities of daily living, work, and leisure activities. Although early studies suggested a self limiting condition lasting two to three years,⁸ …