ISAKOS: 2019 Congress in Cancun, Mexico

2019 ISAKOS Biennial Congress ePoster #1917


Arthroscopic Subacromial Decompression for Shoulder Pain (CSAW): A Multi-Center Placebo-Controlled Randomized Surgical Trial

David J. Beard, MA, MSc, DPhil, FRCS(Hon), Prof., Oxford, Oxfordshire UNITED KINGDOM
Jonathan Rees, MD, Oxford UNITED KINGDOM
Jonathan Cook, PhD, Oxford, Oxfordshire UNITED KINGDOM
Marcus Jepson, PhD, Bristol UNITED KINGDOM
Beverly A. Shirkey, PhD, Oxford UNITED KINGDOM
Cushla D. Cooper, MSc, Oxford, Oxfordshire UNITED KINGDOM
Ines Rombach, DPhil, Oxford UNITED KINGDOM
Steve J. Gwilym, FRCS, DPhil, Oxford UNITED KINGDOM
Andrew Carr, Prof., Oxford, Oxfordshire UNITED KINGDOM
CSAW Study Group, Research Group, Oxford UNITED KINGDOM

University of Oxford, Oxford, UNITED KINGDOM

FDA Status Cleared


A multicentre RCT of 313 patients found arthroscopic decompression for shoulder pain was no different to placebo intervention and provided little extra benefit to no treatment.



Arthroscopic sub-acromial decompression (decompressing the sub-acromial space by removing bone spurs and soft tissue arthroscopically) is a common surgery for subacromial shoulder pain, but its effectiveness is uncertain. A trial was conducted to assess its effectiveness and to investigate the mechanism for surgical decompression.


A multicentre, randomised, pragmatic, parallel group, placebo-controlled, three-group trial at 32 hospitals (51 surgeons) was completed. Participants were patients who had subacromial pain for at least 3 months with intact rotator cuff tendons, were eligible for arthroscopic surgery, and had previously completed a non-operative management programme that included exercise therapy and at least one steroid injection. Exclusion criteria included a full-thickness torn rotator cuff. Patients were randomly assigned (1:1:1) to arthroscopic subacromial decompression, investigational arthroscopy only, or no treatment (attendance of one reassessment appointment with a specialist shoulder clinician 3 months after study entry, but no intervention). Arthroscopy only was a placebo as the essential surgical element (bone and soft tissue removal) was omitted. In the surgical intervention groups, patients were not told which type of surgery they were receiving (to ensure masking). Patients were followed up at 6 months and 1 year after randomisation. The primary outcome was the Oxford Shoulder Score (0 [worst] to 48 [best]) at 6 months, analysed by intention to treat. The sample size calculation was based upon a target difference of 4·5 points (SD 9·0).
Between 2012, and 2015, 313 patients were randomly assigned to treatment groups (106 to decompression surgery, 103 to arthroscopy only, and 104 to no treatment). At 6 months, data for the Oxford Shoulder Score were available for 90 patients assigned to decompression, 94 to arthroscopy, and 90 to no treatment.
Mean Oxford Shoulder Score did not differ between the two surgical groups at 6 months (decompression mean 32·7 points [SD 11·6] vs arthroscopy mean 34·2 points [9·2]; mean difference –1·3 points (95% CI –3·9 to 1·3, p=0·31). Both surgical groups showed a small benefit over no treatment (mean 29·4 points [SD 11·9], mean difference vs decompression 2·8 points [95% CI 0·5–5·2], p=0·02; mean difference vs arthroscopy 4·2 [1·8–6·6], p=0·001) but these differences were not clinically important. There were six study related complications that were all frozen shoulders (in two patients in each group).
Surgical groups had better outcomes for shoulder pain and function compared with no treatment but this difference was not clinically important. Additionally, surgical decompression appeared to offer no extra benefit over arthroscopy only. The difference between the surgical groups and no treatment might be the result of, for instance, a placebo effect or postoperative physiotherapy. The findings question the value of this operation for these indications, and this should be communicated to patients during the shared treatment decision-making process.