ARC (Australian Rotator Cuff) trial: study protocol for a randomised placebo-controlled trial comparing rotator cuff repair to no repair during arthroscopic shoulder surgery for people with shoulder pain and non-acute rotator cuff tears

Background Degenerative rotator cuff tears are common and are often treated with surgical repair. Randomised trials have not shown a clear advantage to surgery over non-surgical treatment, but there have been no published placebo-controlled trials investigating rotator cuff repair. This study aims to compare arthroscopic shoulder surgery with rotator cuff repair to surgery without rotator cuff repair (placebo) for improving shoulder pain and function in people with shoulder pain and full-thickness degenerative rotator cuff tears. Methods The study is a multicentre two-parallel arm, blinded, individually randomised controlled trial (RCT). Participants will be people aged 40-75 years (inclusive) with more than 6 months of shoulder pain, a degenerative (non-traumatic) full thickness rotator cuff tear 1 to 4 cm in length for whom surgery is recommended and repair of the tear is the main reason for surgery. The intervention is arthroscopic surgery (including-as indicated-bursectomy, debridement, acromioclavicular joint resection, acromioplasty and biceps tenodesis or tenotomy) with rotator cuff repair. The control is the same arthroscopic shoulder surgery without rotator cuff repair. Participants will be randomised to cuff repair or no cuff repair in a 1:1 ratio intra-operatively, after all other surgical procedures have been performed. Participants, follow-up surgeons, physiotherapists, study staff and statisticians will be blinded. Post-surgical rehabilitation will be usual care for rotator cuff repair in both groups. The primary outcome will be shoulder pain and function measured using the Western Ontario Rotator Cuff Index at 6 months post-surgery. Discussion The ARC trial will provide low bias evidence on a common surgical procedure: rotator cuff repair for degenerative tears. Trial registration The trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12620000789965) on 5 August 2020 and the WHO International Clinical Trials Registry Platform (universal trial number U1111-1251-6599).