Imaging description

In the setting of blunt trauma to the chest, injuries such as rib fractures, pneumothorax, hemothorax, and pulmonary contusions are relatively common and easily diagnosed by CT if not by radiograph. Fractures of the sternum and scapula and sternoclavicular joint dislocation are less common but reflect higher-energy trauma. Furthermore, they can be easily overlooked, even on CT.

Fractures of the sternum occur in up to 10% of polytrauma cases [1]. Substernal mediastinal hemorrhage should prompt close examination of the sternum, though hemorrhage is not universally present (Figure 84.1). The horizontal sternal fracture may be occult on axial CT images, and dedicated reformations in sagittal and coronal planes relative to the sternum may be necessary for diagnosis (Figure 84.2). An important caveat is that motion artifact may create artifactual step-off in the sternum, but close inspection for matching step-off in the overlying skin line usually helps differentiation. Because sternal fractures usually result from direct frontal injury, additional thoracic, cardiac, and spinal injuries should be excluded (Figure 84.3) [2].

Sternoclavicular dislocation is a rare injury. Anterior dislocations are more common than posterior and are usually clinically obvious. Posterior dislocations, conversely, are often clinically and radiographically occult. Furthermore, the posteriorly dislocated clavicle may be associated with vascular, nerve, or tracheal injuries, necessitating further evaluation. For greater detail, see Case 36.