Randomised controlled trials (RCTs) comparing subacromial decompression with conservative treatment for subacromial impingement syndrome were eligible for inclusion. Eligible participants had to be over 18 years of age and resistant to conservative treatments for at least three months. Trials focusing on surgical repair of rotator cuff tears, adhesive capsulitis and shoulder instability were excluded. Diagnosis of subacromial impingement syndrome, presenting as pain upon abduction of the shoulder, had to be confirmed with a positive result on an impingement test, where elimination or a significant reduction of pain constituted a positive impingement test result. All outcome measures for shoulder function or pain were eligible for inclusion.
In the included trials arthroscopic subacromial decompression was compared with conservative treatment (supervised exercises, education, physiotherapy, physiotherapy with non-steroidal anti-inflammatory drugs and corticosteroid injections, and detuned soft laser treatment). Participants in the included trials had a mean age ranging from 42 to 59 years; duration of complaints, where given, ranged up to almost four years.
Two reviewers independently selected studies for inclusion in the review, with disagreements resolved through consultation with a third reviewer.