STANDARDIZED ULTRASOUND EXAMINATION FOR EVALUATION OF INSTABILITY OF THE ACROMIOCLAVICULAR JOINT

Anteroposterior X-ray views of both acromioclavicular (AC) joints with 10-kg weights held in each hand are the generally accepted procedure for diagnosis of Tossy I-III grades of AC joint separation. An analogo us diagnosis can be made by standardized ultrasound examination. Ten i ndividuals with Tossy-I, 11 with Tossy-II and 8 with Tossy-III instabi lity were examined both radiographically and by B-mode ultrasound. The degree of AC joint separation was uniformly determined on the basis o f a calculated index (AC Index = AC joint width of uninjured side/AC j oint width of injured side). The mean AC Index for Tossy-I instability determined by ultrasound was 1.0; mean indices of 0.49 and 0.5 were d etermined for Tossy-II injury by ultrasound and X-ray, respectively, a nd of 0.21 and 0.2, respectively, for Tossy-III instability. Statistic al analysis showed significant differences between the mean AC indices of all three groups (P < 0.0001). We conclude that the reliability of ultrasound examination of AC joint instability is equal to that of ra diographic measurement. Standard X-rays of the shoulder remain mandato ry only to exclude fracture. The indication for operative stabilizatio n of the AC joint can be established on the basis of the grade of AC j oint instability measured by the side-effect-free and cost-effective m ethod of ultrasound examination (AC Index < 0.3 equivalent to Tossy-II I instability).