Comparison of Anterior and Posterior Cortico-steroid Injections for Pain Relief and Functional Improvement in Shoulder Impingement Syndrome.

Subacromial impingement syndrome (SIS) is the most common cause of shoulder pain. Treatment options for SIS include conservative modalities such as use of nonsteroidal anti-inflammatory drugs, physical therapy, and subacromial corticosteroid injections (CSIs). Although studies have found improvement in pain, function, and range of motion after CSI, the effect of injection route (anterior or posterior) on shoulder pain in patients with SIS has not been investigated. In the study reported here, patients were randomly assigned to 2 treatment groups: anterior CSI and posterior CSI. Pain was assessed with a visual analog scale (VAS) and function with the Single Assessment Numeric Evaluation (SANE). Patients were evaluated before injection (baseline) and 1, 3, and 6 months after injection. Of the 55 patients enrolled, 25 received anterior CSI and 30 received posterior CSI. The 2 groups showed no significant difference in VAS pain at baseline or 1, 3, or 6 months after injection. SANE scores were statistically different at 3 months. Each group had significantly less pain and better function 1, 3, and 6 months after injection than at baseline. Age, sex, and body mass index did not significantly affect the efficacy of anterior or posterior CSIs. In patients with SIS, subacromial CSI reduces pain and improves function for up to 6 months. These effects are no different for anterior and posterior injection routes. As a result, clinicians should rely on their clinical acumen when selecting injection routes, as anterior and posterior are both beneficial.