Effectiveness of High-volume Corticosteroid Injection Diluted With Saline in Subacromial Impingement Syndrome: A Prospective Randomized Trial

Subacromial impingement syndrome (SIS) is commonly treated conservatively with corticosteroid (CS) injections into the subacromial bursa, often combined with local anesthetics (LA). Despite widespread use, there remains no consensus regarding the optimal injection technique, volume, or drug formulation. Some studies suggest high-volume injections may provide superior pain relief, while others show no significant difference. To clarify this, a prospective, double-blind, randomized controlled trial was designed to compare the efficacy and safety of high-volume versus low-volume CS injections in patients with SIS.

Material and methods:

This study is a prospective, double-blind, randomized controlled trial. The study procedure was discussed with the patients, and each participant provided written informed consent.

All patients who were admitted to the outpatient clinic with unilateral shoulder pain within the study period, were screened to assess eligibility for the study The following 3-step checklist was completed for an accurate diagnosis of SIS: history of anterolateral arm pain and exacerbation of symptoms upon raising the shoulder to 90° or higher, a combination of the Neer test, Hawkins-Kennedy test, painful-arc test, and infraspinatus muscle test produced at least 2 positive results and confirmation of the diagnosis by an ultrasound (US) evaluation of the affected shoulder.

The same physiatrist (who had 5 years of experience in musculoskeletal US) performed the complete standard US evaluation of the affected shoulder in each patient, according to the EURO-MUSCULUS/USPRM shoulder scanning protocol. All patients also underwent dynamic US evaluation for SIS . A 3-16-mHz linear probe was used in B mode (Samsung HM70A Plus, Seoul, South Korea). For the US diagnosis of SIS, the subacromial-subdeltoid bursa must have been thicker than 2 mm (bursitis) and a sign of impingement must have been seen on the dynamic evaluations. Any pathological abnormalities associated with SIS (tendinosis, partial-thickness rotator cuff tear, etc.) were also noted.