Does adding ultrasound-guided subacromial injection improve clinical outcomes after suprascapular nerve block in chronic subacromial impingement syndrome?

Ultrasound-guided suprascapular nerve block (SSNB) and subacromial injection (SI) are commonly used for chronic subacromial impingement syndrome (SIS), but the additional benefit of combining these interventions remains uncertain. This study evaluated whether adding ultrasound-guided SI to SSNB improves clinical outcomes in patients with chronic MRI-confirmed SIS who had failed conservative treatment. This retrospective cohort study included consecutive patients with chronic SIS treated between December 2021 and January 2025. Patients underwent ultrasound-guided SSNB alone or combined SSNB with SI according to routine clinical practice. SIS was classified by MRI as grade 1 (tendinopathy), grade 2 (partial-thickness rotator cuff tear), or grade 3 (full-thickness rotator cuff tear). The primary outcome was treatment success, defined as a ≥50% reduction in Numerical Rating Scale (NRS) score at 3 months. Secondary outcomes included pain intensity, patient satisfaction, and treatment outcomes according to MRI grade. Sixty-one patients were included (30 SSNB and 31 SSNB + SI). Both treatment groups demonstrated substantial pain reduction during follow-up. Treatment success rates were similar between the SSNB and SSNB + SI groups (86.7% vs 87.1%, P = .999), as were patient satisfaction rates (86.7% vs 87.1%, P = .946). No significant between-group differences were observed in NRS scores at 1 or 3 months. Treatment success was significantly higher in patients with grade 1 SIS than in those with grade 2 SIS (97.4% vs 80.0%, P = .044). All 3 patients with grade 3 SIS experienced treatment failure. Ultrasound-guided SSNB was associated with favorable short-term outcomes in patients with chronic SIS who had failed conservative treatment. Adding ultrasound-guided SI did not provide additional improvement in pain, treatment success, or patient satisfaction over 3 months. Higher treatment success was observed in patients with grade 1 SIS than in those with more advanced disease. Larger prospective randomized studies are needed to confirm these findings.