Accuracy of placement of ultrasound-guided corticosteroid injection for subacromial pain (impingement) syndrome does not influence pain and function: Secondary analysis of a randomised controlled trial.

Abstract

To investigate whether the accuracy of placement of ultrasound-guided (US-guided) corticosteroid injections for subacromial pain (impingement) syndrome (SAPS) influences pain and function outcomes. This was a secondary analysis of data collected in a previous randomised controlled trial (RCT). Video images of US-guided subacromial corticosteroid injections delivered in the RCT were reviewed to categorise injection accuracy into three groups: definitely/probably not in the subacromial bursa (Group 1); probably in the subacromial bursa (Group 2); and definitely in the subacromial bursa (Group3). The primary outcome was the Shoulder Pain and Disability Index (SPADI) totalscore. Secondary outcomes included SPADI pain and function subscales andparticipants' self-reported global impression of change. Outcomes were compared between the accuracy groups after adjusting for pre-selected baseline characteristics. US-guided injection accuracy data were available for 114 participants: 22 categorised into Group 1, 21 into Group 2 and 71 into Group 3. There were no significant differences in mean total SPADI scores between the three injection accuracy groups at 6weeks (Group 2 vs. 1: 8.22 (95% CI -4.01, 20.50); Group 3 versus 1: -0.57 (95% CI -10.27, 9.13) or 6months (Group 2 vs. 1: 12.38 (95% CI -5.34, 30.10); Group 3 versus 1: 3.10 (95% CI -11.04, 17.23). The accuracy of injection placement in SAPS did not influence pain and function, suggesting that improvements in patients' outcomes using subacromial corticosteroid injections can be achieved without US guidance.