BACKGROUND: Frozen shoulder causes pain and stiffness. It affects around 10% of people in their fifties and is slightly more common in women. Costly and invasive surgical interventions are used, without high-quality evidence that these are effective. OBJECTIVES: To compare the clinical effectiveness and cost-effectiveness of three treatments in secondary care for adults with frozen shoulder; to qualitatively explore the acceptability of these treatments to patients and health-care professionals; and to update a systematic review to explore the trial findings in the context of existing evidence for the three treatments. DESIGN: This was a pragmatic, parallel-group, multicentre, open-label, three-arm, randomised superiority trial with unequal allocation (2 : 2 : 1). An economic evaluation and a nested qualitative study were also carried out. SETTING: The orthopaedic departments of 35 hospitals across the UK were recruited from April 2015, with final follow-up in December 2018. PARTICIPANTS: Participants were adults (aged ≥ 18 years) with unilateral frozen shoulder, characterised by restriction of passive external rotation in the affected shoulder to