ARC

Why is this trial  needed?

The ARC Trial is a multicentre, randomised, placebo-controlled clinical trial investigating the effectiveness of rotator cuff repair in people with chronic shoulder pain and non-acute(degenerative) full-thickness rotator cuff tears.

Degenerative rotator cuff tears are common, particularly in adults over 45 years of age, and surgical repair is one of the most frequently performed shoulder procedures worldwide, and in Finland, currently the most common shoulder procedure. However, despite its widespread use, high-quality evidence demonstrating that rotator cuff repair provides meaningful benefit over non-surgical treatment, or over arthroscopic surgery without repair, is lacking.

Previous research has questioned the value of other common shoulder procedures, and for subacromial decompression, it turned out to be non-effective. To date, no published placebo-controlled trial has rigorously evaluated the specific effect of the repair of a degenerative rotator cuff tear.

The ARC Trial addresses this critical evidence gap.

Given the high prevalence of shoulder pain and the increasing rates of rotator cuff surgery globally, the findings of the ARC Trial have the potential to directly influence clinical guidelines, surgical decision-making, and patient care worldwide.

Study Design

The ARC Trial is a multicentre, two-arm, blinded, randomised controlled trial with an observational cohort for people declining randomisation.

Participants:

•⁠  ⁠Aged 45–75 years

•⁠  ⁠At least 6 months of shoulder pain

•⁠  ⁠MRI-confirmed degenerative full-thickness supraspinatus tear (1–4 cm)

•⁠  ⁠Surgery recommended primarily for rotator cuff repair

All participants undergo arthroscopic shoulder surgery. Once a supraspinatus tendon tear that meets the inclusion criteria is confirmed during arthroscopy and all standard arthroscopic procedures (e.g., bursectomy, acromioplasty, and biceps procedures) have been completed, participants are randomized intra-operatively to:

1.⁠ ⁠Rotator cuff repair, or

2.⁠ ⁠No rotator cuff repair (placebo surgery)

Importantly, participants, physiotherapists, follow-up surgeons, researchers and statisticians remain blinded to treatment allocation.

Both groups receive post-operative physiotherapy.

Eligible patients who do not wish to be randomized may provide informed consent to participate in the observational cohort.

Outcomes

The primary outcome is shoulder pain and function at 6 months, measured using the Western Ontario Rotator Cuff Index (WORC).

Secondary outcomes include:

•⁠  ⁠Health-related quality of life (EQ-5D-5L)

•⁠  ⁠Shoulder pain at rest and with activity

•⁠  ⁠Patient global perceived improvement

•⁠  ⁠Work status

•⁠  ⁠MRI assessment of tendon integrity at 12 months

•⁠  ⁠Complications and adverse events

Participants are followed for up to 2 years, with planned longer-term follow-ups at 5 and 10year time-points.

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The lead investigator Professor Ian harris is telling about ARC study and what it means to participate in it.

Where are we now?

The ARC study was initiated as a multicenter clinical trial in Australia and the lead investigator of the ARC Trial is Professor Ian Harris from University of New South Wales, Sydney.  In February 2026, the FICEBO research group joined in conducting the study at HUS Helsinki University Hospital, as the only research center outside Australia.

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We have already published:

• Protocol article in Trials  

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Project Team (Finland):

Teppo Järvinen – Tuomas Lähdeoja – Thomas Ibounig – Pirjo Toivonen – Robert Björkenheim – Mikko Salmela – Leena Caravitis – Saara Raatikainen – Riikka Korpi – Eerik Hällfors

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