Purpose: To assess the diagnostic potential of ultrasound as compared to conventional radiography in quantifying the anatomic and structural damage and determining the grade of acute traumatic lesions of the acromioclavicular (AC) joint.
Materials and methods: From September 2001 to September 2002, 18 patients (16 men, 2 women; age range: 17-78 years) who came to our Emergency Service with clinically suspected acute traumatic AC joint lesion were examined by ultrasonography with a variable frequency linear-array transducer (7.5-12 Mhz). The morphology of the AC joint peri-articular ligaments and soft tissues, distance between the edge of the acromion and the lateral margin of the clavicle, distance between the superior edge of the coracoid and the inferior margin of the clavicle were evaluated. Conventional radiography was performed prior to ultrasound using routine antero-posterior (A-P), single-film stress and "outlet" projections. All patients subsequently underwent clinical follow-up for a mean period of six months.
Results: On US examination, all patients presented AC ligament lesion associated with consistent intra- and extra-articular sero-haemorrhagic effusion. Six of the 18 patients had suffered indirect trauma. Diastasis of the AC joint with ligament lesion not associated with involvement of coracoclavicular (CC) joint and with ligament integrity was observed. Twelve of the 18 patients had direct trauma. Changes to AC and CC ligaments with consequent diastasis of both joints were observed. Measurements of AC and CC distance obtained on US examination corresponded to those obtained at conventional radiography in the A-P projection. At clinical follow-up, no variation in the previously established diagnosis was recorded in any patient.
Conclusions: If appropriate methodology and adequate transducers are used, ultrasound is an accurate and reliable technique for the evaluation of acute AC joint injuries, complementing and correlating well with conventional radiography.