Correlation of ultrasonographic findings to Tossy's and Rockwood's classification of acromioclavicular joint injuries.

The aim of this study was to examine the value of ultrasonography to assess high-graded acromioclavicular (AC) joint injuries. We propose a new sonographic technique to evaluate the state of the soft tissues, specifically the deltoid and trapezoid muscles and their common fascia. Radiologic findings graded by Tossy's and Rockwood's classification were compared with sonographic findings for 92 patients with high-grade injuries of the AC joint. Of the 92 patients, 39 underwent operative treatment. A total of 36 patients were radiographically classified as type II and 56 with type III injuries, according to Tossy. In 4 cases, ultrasonography displayed disrupted insertions of the deltoid and, in 30 patients, of the trapezius muscle. All patients classified as type V, eight of 18 patients classified as type IV, nine of 31 patients classified as type III and two of 28 patients classified as type II injuries, according to Rockwood's classification, displayed a disrupted deltoid and trapezius insertion and common fascia on ultrasound (US). Comparison between sonographic and intraoperative findings revealed a sensitivity for diagnosing delta muscle detachment and fascial disruption of 100%. No true-negative results occurred. For trapezius muscle detachment, 24 of 30 patients were diagnosed correctly and nine true-negative results occurred. False-positive results were not encountered. The sensitivity was 80%. The specificity was 100%. We conclude that US provides additional information concerning soft tissues and that it may be useful to delineate type III injuries, in which nonoperative vs. operative treatment is still being debated. Diagnosis based only on sagittal X-ray examination may under- or over-estimate the soft tissue injury involved. Additional transaxillary X-ray as well as an US evaluation may need to be included in the diagnostic process. We propose this new sonographic technique for future studies.