Radiographic evaluation of the acromioclavicular and sternoclavicular joints.

Plain radiography is useful for the initial assessment of suspected disorders of the sternoclavicular and acromioclavicular joints. Other modalities are often required to further assess more complex pathologies involving these joints, however. Ultrasound has been described as a screening tool to assess possible sternoclavicular joint dislocation; however, it is usually used only if CT and MRI are not readily available. It has also been used to confirm intraoperative relocation. Ultrasound has a limited role in the evaluation of the AC joint, where it is most useful to exclude the presence of joint inflammation. If joint fluid is detected sonographically, it is considered a nonspecific finding, which could represent active inflammation or simply joint effusion due to degenerative arthrosis. CT allows for excellent visualization of the articular surfaces, osseous changes, subtle or complex fractures, and joint malalignment, with a rapid scan time, making it particularly helpful in the work up of trauma patients. With its multiplanar capabilities and superior soft-tissue resolution, MRI is a very effective modality for characterizing soft-tissue injuries, inclusive of ligamentous tears and cartilaginous injuries. In the specific case of posterior sternoclavicular dislocations, both CT and MR angiography can be very helpful in elucidating occult associated vascular injury.