Shoulder pain is common and subacromial compression for subacromial shoulder pain is one of the commonest surgical procedures in orthopaedics. Despite a lack of reliable evidence for its effectiveness, the number of patients undergoing subacromial decompression has substantially increased in recent years; in 2000 around 2,500 patients in the UK underwent subacromial decompression and by 2010 this had increased to more than 21,000.
The present trial was a multicentre, randomised, pragmatic, parallel group, placebo controlled, three group trial at 30 hospital sites in the UK. The intervention arm was arthroscopic subacromial compression. The placebo surgical intervention was investigational arthroscopy only where no bone and tissue were removed. The third arm was a no treatment arm. Patients in the surgical arms were masked to their treatment assignment, but patients in the no treatment arm were unblinded. Blinded outcome assessment was done in all groups.
Eligible participants had to have subacromial shoulder pain of at least 3 months duration with intact rotator cuff tendons, be eligible for arthroscopic surgery, and to have previously completed a non-surgical management programme that included both exercise therapy and at least one steroid injection. The primary outcome measure was the Oxford Shoulder Score (a patient reported questionnaire and an effective measure of change in pain and function in shoulders over time) at 6 months. The main analysis was according to intention-to-treat.
A total of 313 participants were randomised comprising 106 patients to decompression surgery, 103 assigned to arthroscopy and 104 assigned 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 32·7 points [SD 11·6] vs arthroscopy 34·2 points [9·2]; mean difference −1·3 points (95% CI −3·9 to 1·3, p=0·3141). Both surgical groups showed a small benefit over no treatment (mean 29·4 points [SD 11·9], decompression was higher by 2·8 points [95% CI 0·5–5·2], p=0·0186; mean difference vs arthroscopy by 4·2 points [1·8–6·6], p=0·0014) but these differences were not clinically important. A range of secondary outcomes, comprising further shoulder pain scales and more general quality of life, showed the same pattern of results as the primary outcome.
In conclusion, the authors state that in patients with persistent subacromial shoulder pain due to impingement, improvement in Oxford Shoulder Scores with arthroscopic subacromial decompression did not differ to that achieved with arthroscopy only (placebo surgery). Although both types of surgery provide greater symptom improvement than no treatment, this difference was of uncertain clinical significance. The difference between surgery and no treatment might be due to a surgical placebo effect, or possibly caused by other factors, including rest and/or post-operative physiotherapy. There were also no differences in outcome between the two surgical groups at any time point. This finding suggests that the treatment effect is not due to the principal clinical justification for the surgery, which is the removal of bone, bursa, and soft tissue to relieve impingement on the underlying tendons during movement of the arm.
The full report of the study can be found here.