An ultrasound guided injection (USG) of the subacromial-subdeltoid (SASD) bursa could be done by placing the transducer along the long axis of the supraspinatus tendon. The SASD bursa can be visualized as an anechoic/hypoechoic linear structure, between the deltoid muscle and supraspinatus tendon, and extending to the area distal to the insertion of the supraspinatus tendon at the greater tubercle. The outer and inner layers of the bursa are usually outlined by peribursal fat that appears as two hyper-echoic strips. According to Chang et al (2018) the needle is introduced from proximal/lateral directed to distal/medial until the tip reaches the space interposed between the peribursal fat layers.
The thickness of the subdeltoid bursa, dynamic subacromial impingement assessment, the side involved, and response to subacromial lidocaine injection have all been reported as predictors of success with USG injections of the SASD bursa.