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.
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.
