[Which ultrasound scan is the best to detect glenohumeral joint effusions?]

It has not yet been systematically investigated which ultrasound scan is the best for detecting effusions of the glenohumeral joint. This question will be addressed by this study. Furthermore, this study determines reference values for distances to distinguish effusions from normal findings.

Ultrasound was performed according to extended DEGUM and EULAR guidelines on 200 shoulders of 100 consecutive patients with shoulder complaints and on 40 shoulders of 20 healthy controls. Distances were measured between the surface of the humerus and the joint capsule in 3 positions: Axillary recess, dorsal transverse scan with 60 degrees internal rotation and with maximum external rotation. Normal values were calculated by ROC analysis.

The mean age of patients and controls was 58 and 55 years, and 67 % and 70 % were female, respectively. Ultrasound detected effusions in 81 shoulders of 56 patients. Effusions were seen in the dorsal scan with 60 degrees internal rotation in 30 %, in the axillary scan in 49 %, and in the dorsal scan in maximum external rotation in 94 % (p < 0.001, respectively). Five percent of the effusions were exclusively detected in the axillary scan. The upper normal limits for the distance between bone surface and joint capsule were 3.7 mm for the axillary recess, 2.7 mm for the dorsal region in 60 degrees internal rotation and 3.1 mm for the dorsal region in maximum external rotation .

Dynamic ultrasound examination including the dorsal scan with maximum external rotation is essential for detecting glenohumeral joint effusions. The axillary scan is superior to the dorsal transverse scan with 60 degrees internal rotation.