A majority of sternal fractures occur transversely across the midbody, but may also be seen at the manubrium. In general, the sternum is initially imaged with PA and lateral chest radiographs, but more sensitive dedicated sternal views are also available when clinical suspicion is high. The lateral chest x-ray provides more value in identifying sternal fractures and their degree of displacement than the PA view. With the advent of later generation CT scanners and their expanded use in trauma patients, CT often identifies sternal fractures and is greater in sensitivity and specificity than plain radiographs. CT is also useful to identify associated thoracic or cardiopulmonary injuries, which are of greater clinical importance than the fracture itself.
Sternal fractures are usually associated with direct blunt traumatic injury to the chest sustained in a motor vehicle crash, but stress fractures may also be encountered. Sternal fractures are painful injuries resulting in decreased respiratory excursion and pulmonary atelectasis, so outpatient management should consist of adequate analgesia and incentive spirometry. Sternal fractures may be associated with acute life-threatening intrathoracic injuries such as cardiac contusion, mediastinal injury and bleeding, aortic injury, flail chest, pneumothorax or hemothorax, pulmonary contusions and lacerations, and compression fractures of the ribs and thoracic spine. Because of the high morbidity and mortality of concomitant injuries, a high index of suspicion should be held for associated injuries when sternal fracture is diagnosed.
Figure 4.1 ▪ Sternal Fracture.
The lateral chest radiograph adequately shows the mildly posteriorly displaced fracture of the sternal body (arrow).
Figure 4.2 ▪ Sternum Fracture.
A, B: An axial and a sagittal CT image of the chest in another patient show a mildly displaced sternal fracture with hematoma formation about the fracture site. Anteriorly displaced sternal fractures, such as this, have a high association with flexion injury of the thoracic spine.
Identification of associated injuries carrying high morbidity and mortality is of paramount importance when considering the diagnosis of sternal fracture.
Dedicated sternal views are more sensitive than PA and lateral chest radiographs in identifying sternal fractures by changing the viewing angle and exposure of the radiograph. These should be considered when clinical suspicion is high and chest radiographs are negative, unless a CT is to be performed.
A clue to look for a subtle sternal fracture on CT is retrosternal hematoma formation.
Anteriorly displaced sternal body fractures are commonly associated with flexion injuries of the thoracic spine.
Figure 4.3 ▪ Manubrium Fracture.
A lateral view of the sternum nicely demonstrates buckling of the manubrium in this nondisplaced fracture (arrow).