The aim of this study was to evaluate the usefulness of the 3 dimensional ultrasonography (3D ) of the supraspinatus (SSp) tendon and the low echoic area of the tendon. 2 and 3 dimensional ultrasonographies were performed on the SSp tendons of 97 patients. The right shoulders were involved in 54, left in 28 and both in 15 patients. Ultrasonograms were divided into 2 groups with or without complaint and were compared. In 2 dimentional ultrasonographies (2D), the configurations of the sagittal section of SSp tendons classified into 4 types and the echogenesity classified into 4 types were studied. In 3D, configurations of the serial sagittal sections were classified into 3 grades by its clearness and the echogenesity in the tendons were into 4 types respectively. In 2D, 72 concave, 9 flat, 2 irregular types were found in sound shoulders, and 82 concave, 17 flat, 8 irregular and 5 defect were found in involved shoulders. In 2D, moderate or large low echoic area were found in 9 sound shoulders (9.6 %) and 20 involved shoulders(19%). In 3D, the configurations demonstrated good and moderately were found in 72 sound shoulders (72/83 86.7%) and in 97 involved shoulders (97/112 86.6%). In 3D, moderate or large hypoechoic area were found in 40 (58.0%) and 57(64.9%) SSps respectively. In this preliminary study, the rate of manifestation of 3D utrasonography as good or moderately was not satisfied but the better results were expected by technical improvements. Implication of low echogenesity in the SSp tendon was still controversial but the contribution of tendon degeneration might be suspected. 3D ultrasonography could be a useful tool to evaluate the cuff pathology.
