Effect of Needle Type and Concomitant Pathologies on the Efficacy of Corticosteroid Injection in Subacromial Impingement Syndrome.

BACKGROUND: To evaluate the effect of needle type and concomitant pathologies on the efficacy of subacromial corticosteroid injection in patients with subacromial impingement syndrome. METHODS: Forty patients diagnosed with subacromial impingement syndrome were retrospectively analyzed and divided into two groups: Group I (27-gauge/50 mm needle) and Group II (21-gauge/33 mm needle). Painless range of motion (ROM), NRS, SPADI, and DASH scores were assessed pre- and post-injection. MRI was used to determine whether the needle reached the supraspinatus tendon level. The presence of concomitant pathologies was recorded. RESULTS: Both groups showed statistically significant improvements in painless flexion, abduction, and internal rotation ROM, as well as in NRS, SPADI, and DASH scores (p < 0.05). A significant improvement in painless external rotation ROM was observed only in Group II (p  < 0.001). Painless flexion ROM improved more than abduction ROM only in patients without long head of biceps brachii tendinopathy (p  = 0.032). Pre-injection painless abduction ROM was more limited than painless flexion ROM in patients with acromioclavicular joint degeneration (p  = 0.041). CONCLUSIONS: Needle type did not significantly alter treatment efficacy except in external rotation ROM. The long head of biceps brachii tendinopathy may partially benefit from subacromial corticosteroid injection, although the effect appears to be limited. Subacromial corticosteroid injection may offer therapeutic value in patients with acromioclavicular joint degeneration. Individualized needle selection and recognition of concomitant pathologies may optimize clinical outcomes.