General Considerations

• Segment of thoracic cage is separated from remainder of chest wall by significant blunt chest trauma
• Relatively uncommon, but potentially life-threatening
• Definition varies from two fractures per rib for two contiguous ribs to two fractures per rib for three contiguous ribs
• Sternum may also be involved with ribs on both sides of chest
• Severity of underlying lung and cardiac injury are clinically more important than fractures themselves

Clinical Findings

• Chest wall bruising
• Pain on inspiration
• Crepitus
• Flail segment moves paradoxically with respiration
  • Moves inward on inspiration and outward on expiration

Imaging Findings

• Chest radiographs are invariably performed first
  • Two or more fractures in two or three or more contiguous ribs
• Chest x-rays tend to underestimate the number of fractures
• Chest CT is also invariably performed, and may show
• Rib fractures
• Pulmonary contusion (almost always)
• Airspace disease representing hemorrhage into the alveoli usually subjacent to the point of impact
• Pulmonary laceration
• Lacerations in the lung may be blood-containing, air-containing, or both
• Frequently masked by the surrounding pulmonary contusion
• Pneumothorax (very common)
• Since the severity of the injury means a supine radiograph will be performed, pneumothoraces may only be seen on chest CT
• Hemothorax (common)
• Pneumomediastinum
• Subcutaneous emphysema
• Mediastinal hemorrhage
• Aortic injuries

Treatment

• Analgesia, including intercostal nerve blocks
• Ventilation and oxygenation
  • Patients who do not need mechanical ventilation do better than those who do

Complications

• Almost always accompanied by pulmonary contusion
• May have long-term disability
  • Chest wall pain
• Respiratory distress

Prognosis

• Up to 10% mortality if patients reach hospital alive
  
  

Flail Chest. Radiograph at left and CT at right demonstrate multiple rib fractures (white arrows) with some ribs fractured in two or more places (see CT scan). There is also a pulmonary contusion (red arrow), subcutaneous emphysema (yellow arrows) and a fracture of the left transverse process of the vertebral body imaged on the CT scan.
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eMedicine: Flail Chest.  Bjerke, H