Flail chest

Last revised by Daniel J Bell on 28 Oct 2023

Flail chest or flail thoracic segment implies paradoxical motion of a segment of chest wall during respiration due to multiple rib fractures. Definitions vary; radiologists apply the term when three or more contiguous ribs are fractured in two or more places. Clinically, a segment of only one or two ribs can act as a flail segment especially if the fractures are displaced.

Ventilatory difficulty following trauma with paradoxical movement of the flail segment; occasionally clinically occult 4,5.

A flail chest is a marker for chest trauma severity and is commonly associated with other thoracic injuries which can contribute to respiratory insufficiency, such as 1,2,5:

Bilateral anterior rib or costal cartilage fractures can give rise to a flail sternum.

Rarely the flail segment of the chest wall may collapse inwards, causing stove-in chest which is associated with even higher morbidity and mortality 7.

Flail chest is most commonly caused by high-impact blunt thoracic trauma and severe anteroposterior compression which is typically the result of motor vehicle accidents, blast injuries or crush injuries 5.

A chest x-ray is less sensitive than CT for the diagnosis of flail segments 4:

  • defined as ≥3 adjacent ribs with segmental fractures and/or >5 adjacent rib fractures

  • 1st rib fractures are a marker of severe chest trauma. as this rib is protected by the clavicle and scapula. First rib fractures are associated with a10% incidence of aortic transection and a 2% incidence of bronchial tear

  • costal hook sign: elephant trunk-shaped ribs owing to rotation of segmental fractures

Non-invasive positive pressure ventilation through a well-fitting mask with oxygen supplementation is often sufficient and has fewer iatrogenic complications. Atelectasis, pneumonia and ARDS are common complications.

Patients who undergo mechanical ventilation and surgical fixation have higher morbidity and mortality rates.

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Figure 1: illustration
    Drag here to reorder.
  • Case 1: flail segment
    Drag here to reorder.
  • Case 1: post internal fixation
    Drag here to reorder.
  • Case 2: right flail
    Drag here to reorder.
  • Case 3
    Drag here to reorder.
  • Case 4
    Drag here to reorder.
  • Case 5
    Drag here to reorder.
  • Case 6: rib plating for flail segment
    Drag here to reorder.
  • Case 7
    Drag here to reorder.
  • Case 8
    Drag here to reorder.