Effectiveness of High-Volume Corticosteroid Injection in Shoulder Impingement

Inclusion Criteria: * Diagnosis of subacromial impingement syndrome (SIS) * Age over 18 years * Shoulder pain lasting longer than 4 weeks * Shoulder pain with a visual analogue scale (VAS) score of 3 or higher * Passive shoulder range of motion within normal limits Exclusion Criteria: * Full-thickness tear or calcification of the rotator cuff in the affected shoulder * Adhesive capsulitis * History of trauma or surgery in the affected shoulder * History of injection into the affected shoulder within the previous 6 months * History of systemic rheumatic disease, malignancy, or coagulopathy * Suspected cervical radiculopathy * History of allergy to local anesthetics (LA) and/or corticosteroids (CS)