Ultrasound Identification of Maximal Subdeltoid Bursa Distention Alters the Ultrasound-Guided Injection Approach for Shoulder Pain

Objective: Landmark-guided injections (LMGIs) of corticosteroid (CS) into the subdeltoid bursa (SDB) are typically provided from a posterolateral approach, aiming at the subacromial aspect of the bursa with varying accuracy and response. Ultrasound (US) can visualize bursal abnormalities and is known to improve injection accuracy. Our objective was to evaluate how US affects the injection approach used for treatment of subacromial impingement. Methods: We reviewed clinical and US characteristics of 67 patients with impingement syndrome who received 96 SDB US-guided injections (USGIs) in one rheumatology US clinic. Images were obtained and interpreted by 1 musculoskeletal ultrasound (MSUS) trained rheumatologist and reviewed by 2 MSUS trained physiatrists. Results: Patients were mostly female (62.7%) with a mean age of 63.5±14.7 years and BMI of 28.8±7.02. Twenty-six (38.8%) received prior LMGIs with more than half (61.5%) reporting little to no benefit. USGI approach was determined by localizing the area of maximal SBD thickening and distension on US. USGIs were targeted subacromially in only 40.6% of cases; 59.4% were targeted anterior to the acromion: 37.5% anterior over the subscapularis tendon, 19.8% anterolateral over the supraspinatus tendon, and 2.0% anterior over the biceps tendon. Nearly all patients reported significant improvement immediately post-procedure. Conclusion: Point-of-care US identified SDB abnormality to occur more frequently anterior to the acromion, rather than below it. This may contribute to LMGI failure, as LMGIs are typically directed at the posterior border of the bursa beneath the acromion. This method has the potential to improve clinical outcomes. Future prospective studies are needed.