ULTRASOUND EVALUATION OF THE ACROMIOCLAVICULAR JOINT

Objective. To evaluate the value of ultrasonography in assessing arthr itic acromioclavicular (AC) joints. Methods. One hundred twenty-six AC joints of 63 healthy subjects (2 groups) were prospectively examined by ultrasound to determine the normal limits of capsular distention an d the width of the joint space. Thirty-three AC joints of 32 patients with chronic arthritis were evaluated by ultrasound and, for compariso n, by radiography, computed tomography (CT), and magnetic resonance im aging (MRI). Results. The mean ultrasonographic distance of the joint capsule from the bone rim was 2.2 mm +/- standard deviation (SD) 0.5 m m in 21-32-year-old control subjects and 2.9 +/- 0.7 mm in 37-81-year- old control subjects. The mean width of the joint space was 4.1 +/- 0. 9 mm and 3.5 +/- 0.9 mm in the same control groups, respectively. In d etecting soft tissue changes in arthritic AC joints MRI was better tha n ultrasound. In revealing bony surface changes, CT was the best metho d and radiography was least sensitive but quite specific. Our most pro minent finding was that ultrasound is able to exclude joint inflammati on; when the ultrasonographic distance of the joint capsule from the b one rim was < 3 mm, there was no synovial hypertrophy or effusion on M RI scans. Conclusions. Ultrasound can detect AC joint changes reliably . It is able to exclude joint inflammation. Effusion in the AC joint m ay reflect inflammation, but may also be a sign of degeneration.