Chest ImagingRib fracture
cortical disruption of a rib due to direct
trauma or
pathological processes. Fractures are most often due to car accidents, falls or crush injuries. The majority are isolated and of minor clinical importance. Fractures of the first and second ribs do not have a high association with aortic and
mediastinal injuries as once believed. Fractures of the lower ribs raise the question of injury to the liver or spleen, a potentially serious situation. The fractures of greatest clinical concern are the fractures of multiple ribs at multiple sites or multiple fractures along the costosternal junctions. These result in a flail chest in which the involved portion of the chest shows paradoxical motion with respiration insufficiency. This type of injury is often associated with multiple other intra- and extrathoracic injuries. The flail chest is often more apparent clinically than radiographically.
Although chest radiography will show many rib fractures, oblique films are required to evaluate the curvature of the lateral ribs. Coned views are required to evaluate ribs obscured by upper abdominal organs. When conventional radiographs show comminuted displaced rib fractures, CT is invaluable in determining whether depressed rib fragments have been driven into the lung and require surgical elevation and stabilization. CT will also show sternal fractures and costosternal disruption, which cannot be evaluated by conventional films (Fig.1).
Rib fractures are often accompanied by extrapleural haematomas that present as focal or diffuse pleural thickening. Nontraumatic rib fractures are most frequently pathological fractures. In patients with diffuse osteoporosis (e.g. in old age, steroid administration), fractures may follow vigorous coughing or relatively minor trauma. All other nontraumatic rib fractures should raise the possibility of a pathological fracture due to an underlying malignancy, most often metastatic.
Rarely, part of the lung may herniate through a defect in the chest wall created by a fractured rib and the adjacent fascia and muscle. PEEP (see mechanical ventilation) increases the likelihood of transthoracic lung herniation. The diagnosis can be made by chest radiograph but it is easier to detect by CT or fluoroscopy.
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Flail chest CT demonstrates normal articulation between the right costal cartilage and the sternum. The left costosternal articulations are disrupted at multiple levels and the sternum is also fractured (lower panel). There is a fracture of the anterior rib on the right at the ribcartilage junction (arrow). A chest wall haematoma is also visible but there is no pericardial fluid.
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Rib fracture, Fig.1 | |