Background
Anterior sonography of the glenohumeral joint has been suggested as a useful method of assessing inflammatory joint disease. The proximity of the subscapular tendon (SSC) to the glenohumeral joint (GHJ) in the shoulder might require differentiating between these two structures.
Material and Method
Anterior shoulder sonographic evaluation (Sonosite-Titan) was carried out on four patients: active rheumatoid arthritis (1), osteoarthritis (1), healthy young man (1), silent crystal induced joint disease (1). The shoulder was in a position of supination and external rotation. SSC and GHJ were compared with the transducer located just medial to the biceps tendon (for SSC) and just lateral to the coracoid process (for GHJ). The structural and location differences between the subscapular tendon and the glenohumeral joint on anterior shoulder sonography were discerned. A transverse view of SSC with the transducer located just medial to the biceps tendon (BT) shows the following distinguishing features of the SSC: minor tuberositas, concave surface of the lower surgical neck, fibrillar structure of SSC, continuation of the lower bone margin without demonstration of the thickness of the labrum. A longitudinal view of GHJ with the transducer located just lateral to the coracoid process indicates a rate of GHJ synovial distension, convex, round humeral head with termination of its lower margin and labrum thickening, lack of fibrillar structure of GHJ, and convex round shape of the GHJ capsule.
Results

Conclusions
Differentiating SSC and GHJ on anterior shoulder sonography with above mentioned sonographic features misinterpretation of US data might be minimized.

Keywords: Shoulder Joint - ultrasonography, Shoulder - ultrasonography, Osteoarthritis - ultrasonography, Tendons - ultrasonography, Arthritis, Rheumatoid - ultrasonography