Efficacy of the Local Injection of Methylprednisolone Acetate in the Subacromial Impingement Syndrome. A Randomized, Double-Blind Trial

Background: Local glucocorticosteroid injections are frequently used in the treatment of subacromial impingement syndrome (SIS), however its efficacy is still controversial. Objective: To compare the efficacy of the subacromial injection of methylprenisoloneacetate plus lidocaine (MPL) versus lidocaine alone (LA) in SIS. Material and method: Consecutive SIS subjects, defined as a positive Neer's injection test were randomized to a subacromial injection of 2 mL methylprednisolone acetate (40 mg/ mL) plus 1 mL of 1% lidocaine (27 patients); or 3 mL of 1% lidocaine (29 patients) were studied. The change from baseline of the score of a Spanish validated version of the Shoulder Disability Questionnaire (S-SDQ), pain intensity, and shoulder range of motion were measured at 15 and 30 days, and afterward every month for five months. Results: After adjusting for duration of symptoms and pain intensity at baseline by way of a general lineal model, we did not find differences in the change of S-SDQ scores and shoulder range of motion between the study groups. Subjects randomized to LA had greater improvement of pain intensity than MPL subjects during the entire follow-up. Conclusions: A subacromial injection of methylprednisolone acetate was not more efficacious than the injection of lydocaine alone in patients with SIS.