Aims. Is it feasible to conduct a definitive multicentre trial in community settings of corticosteroid injections (CSI) and hydrodilation (HD) compared to CSI for patients with frozen shoulder? An adequately powered definitive randomized controlled trial (RCT) delivered in primary care will inform clinicians and the public whether hydrodilation is a clinically and cost-effective intervention. In this study, prior to a full RCT, we propose a feasibility trial to evaluate recruitment and retention by patient and clinician willingness of randomization; rates of withdrawal, crossover and attrition; and feasibility of outcome data collection from routine primary and secondary care data. Methods. In the UK, the National Institute for Health and Care Excellence (NICE) advises that prompt early management of frozen shoulder is initiated in primary care settings with analgesia, physiotherapy, and joint injections; most people can be managed without an operation. Currently, there is variation in the type of joint injection: 1) CSI, thought to reduce the inflammation of the capsule reducing pain; and 2) HD, where a small volume of fluid is injected into the shoulder joint along with the steroid, aiming to stretch the capsule of the shoulder to improve pain, but also allowing greater movement. The creation of musculoskeletal hubs nationwide provides infrastructure for the early and effective management of frozen shoulder. This potentially reduces costs to individuals and the wider NHS perhaps negating the need for a secondary care referral. Results. We will conduct a multicentre RCT comparing CSI and HD in combination with CSI alone. Patients aged 18 years and over with a clinical diagnosis of frozen shoulder will be randomized and blinded to receive either CSI and HD in combination, or CSI alone. Feasibility outcomes include the rate of randomization as a proportion of eligible patients and the ability to use routinely collected data for outcome evaluation. This study has involved patients and the public in the trial design, dissemination methods, and how to include groups who are underserved by research. Conclusion. We will disseminate findings among musculoskeletal clinicians via the British Orthopaedic Association, the Chartered Society of Physiotherapy, the Royal College of Radiologists, and the Royal College of General Practitioners. To ensure wide reach we will communicate findings through our established network of charities and organizations, in addition to preparing dissemination findings in Bangla and Urdu (commonly spoken languages in northeast London). If a full trial is shown to be feasible, we will seek additional National Institute for Health and Care Research funding for a definitive RCT. This definitive study will inform NICE guidelines for the management of frozen shoulder. Cite this article: Bone Jt Open 2024;5(3):162–173