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RIB AND STERNAL FRACTURES

RIB AND STERNAL FRACTURES

Thoracic injury is directly responsible for 25% of trauma deaths and contributes to the demise of another 25%. Most mortality directly attributable to chest trauma occurs in the prehospital setting, resulting from disruption of the great vessels, heart, or tracheobronchial tree. Of those who survive the initial insult, fewer than 15% sustain injury that necessitates operative intervention. Although tube thoracostomy is often the only procedure required initially for chest trauma, injuries to the thoracic cage and lung prolong hospitalization and may be the source of long-term morbidity and occasionally death.

A rib fracture is usually the result of a direct force applied to the chest wall. The pattern of rib fractures is primarily determined by the direction of the forces as well as vulnerability without protection of the shoulder girdle. Whereas frontal impact on the steering column from a motor vehicle crash usually produces upper anterior fractures that may have associated costochondral separations, a lateral impact results in middle and lower lateral rib fractures. Lateral and posterior fractures of the 8th, 9th, and 10th ribs are markers for concomitant intraperitoneal injury, notably the spleen on the left side and the liver on the right. Posterior 11th or 12th rib fractures may be associated with renal injury on the involved side.

THORACIC INJURIES


Fracture configuration varies from single cortex involvement that may be difficult to identify radio-graphically to fragmented ribs that may penetrate adjacent intrathoracic structures. Fractures may be transverse or oblique, and the segments may override or be displaced inward, disrupting the adjacent intercostal artery or tearing the pleural and underlying lung. Penetrating injuries, particularly gunshot wounds, may fragment the rib with a piece driven into the lung as a secondary missile. Ribs may also become disengaged from the sternum where they are attached by cartilaginous bridges or occasionally from the vertebral column from ruptured ligaments. Costochondral separation occurs at the rib-cartilage interface, and chondrosternal separation occurs at the cartilage-sternum juncture. The sternum may also become fractured at any point of contact along its course. Sternal fractures imply a major force to the anterior chest and thus should raise concern for underlying cardiac or great vessel injury.

Clinical suspicion of fractures of the ribs or sternum or cartilaginous separation is usually prompted by severe local tenderness or crepitus with respiration. Pain is more evident on inspiration, so patients tend to hypoventilate with significant rib fractures. An antero-posterior (AP) chest radiograph will usually confirm the diagnosis of rib fractures, but a lateral view is more sensitive for sternal fractures. Occasionally, oblique views of the ribs are necessary to identify isolated rib fractures. With multiple fractures, AP and lateral views of the chest are important to identify the location and extent of the fractures, as well as to exclude secondary pneumothorax or hemothorax or mediastinal hematoma caused by associated great vessel injury. A CT scan, usually obtained because of concern for major thoracic trauma, is much better at characterizing fractures and their associated complications.

The management of patients with rib and sternal fractures is fundamentally directed at pain control. The consequences of inadequate pain control are shallow breathing and poor coughing leading to atelectasis, retained secretions, and ultimately pneumonia. Elderly patients with multiple rib fractures are particularly at risk for this scenario, leading to pneumonia. Patients older than age 65 years with more than three rib fractures or any patient with more than five rib fractures should be hospitalized for pain management and pulmonary surveillance. In most trauma centers, epidural anesthesia is used preemptively in high-risk patients.

Intercostal nerve blocks, however, remain a valuable adjunct for treating patients with rib fracture pain. These nerve blocks should be used liberally in the emergency department for high-risk patients awaiting epidural placement and can be used to supplement intravenous opiates in hospitalized patients with multiple fractures. The technique consists of inserting a needle below the inferior border of the rib and injecting an anesthetic agent into the intercostal space containing the nerve. Typically, injections are required into one or two interspaces above and below the fractures to encompass overlapping innervation. Caution must be used in performing intercostal blocks because the underlying pleura can be violated, producing a pneumothorax and, rarely, an intercostal artery can be injured, producing a hemothorax. Additional benefit can be derived from direct injection into the fracture site. Patients must be encouraged to cough frequently and breathe deeply with an incentive spirometer (IS). An IS is also helpful to gauge patient compliance and optimize pain management.