To compare the Oxford shoulder score at 6 months post intervention for primary frozen shoulder randomised to either an arthroscopic capsular release or hydro-dilatation

All potential participants for this study will be identified by an Orthopaedic Shoulder Consultant in the shoulder clinics run at the Royal Devon and Exeter NHS trust. The patients will be screened for eligibility by a research associate (SG). The eligibility criteria will be that the patient is medically fit for an operation, and has severe primary frozen shoulder in the acute painful stage, that is deemed suitable for intervention by the consultant surgeon. The patients will be informed verbally and in writing about the trial by the research associate and informed consent will be taken.

The participating patients will be randomised in a 1:1 allocation to arthroscopic capsular release (ACR) or hydrodilatation (HD). The randomisation will be administered by a central independent randomisation service, provided by a medical secretary using a computer generated randomisation sequence, who is completely independent of the trial.

All patients will be asked to fill out a number of questionnaires prior to surgery: the Oxford Shoulder Score (OSS) and the EQ-5D. The range of movement within the shoulder joint will be documented in a standard fashion.

Each patient will then undergo the assigned procedure according to the randomisation. The ACR would be performed by one of the Consultant Shoulder surgeons in their standard manner. The Hydro-dilatation would be performed by one of the Consultant Musculoskeletal radiologists in their standard manner. This would ensure that the options at each step of the operation or procedure, such as patient positioning, approach to the shoulder joint, and the closure of the wound etc are left entirely to the discretion of the Consultant performing the procedure. This will ensure that the results of the trial can be generalised to as wide a group of patients and surgeons as possible.

After the operation, patients will be reviewed using the range of movement, OSS, a patient satisfaction score and EQ-5D at 6 weeks, 3 months, and 6 months post-operatively. A record will be kept of any complications associated with the treatment. This data will be collected with by the research associate, who is independent of either intervention.

The main analysis will investigate differences in the primary outcome measure the OSS, between the two treatment groups (ACR and HD) on an intention-to-treat basis, at 6 months post-operation. Secondary outcome measures will be analysed in a similar manner. Statistical analysis will be undertaken by a statistician blinded to the interventions. Advice will be sought from an independent statistician provided by the trust to confirm the statistical methodology.

The economic evaluation will investigate the comparative cost-effectiveness of ACR versus HD. Health outcomes within 6 months follow-up will be assessed using the EuroQoL data collected within the trial, which will be valued using the standard UK TTO tariff to produce Quality-Adjusted Life-Year (QALY) estimates.

Inclusion Criteria:

• Medically fit for an operation; normal x-ray; Codmans criteria frozen shoulder

Exclusion Criteria:

• Secondary causes of frozen shoulder; rotator cuff tears found at arthroscopy or hydro-dilatation; unable to adhere to trial protocol

independent clinical reviewer of patients ROM and collection of outcome scores