• More than 50% of acute fractures are missed on the initial CXR • Fractures of the 1st to 3rd ribs imply a severe traumatic force and may be associated with vascular, brachial plexus, spinal, or tracheobronchial injuries • Fractures of the 10th to 12th ribs (often better seen on an AXR) are associated with injuries to the liver, spleen or kidneys • Rib fractures are uncommon in children due to their greater inherent elasticity (if present they are usually of the greenstick variety) • Flail segment: double fractures of ≥3 adjacent ribs (or adjacent combined rib, sternal and costochondral fractures) resulting in a segment of chest wall moving paradoxically during the respiratory cycle • This is commonly seen in major trauma victims (20–30%) • Shock waves can lead to microvessel rupture with intra-alveolar and interstitial haemorrhage, as well as alveolar and interstitial oedema • Opacities appear within 6 h of impact and typically clear within 3–10 days (shadowing increasing over the days following admission is unlikely to be due to a simple contusion but may be due to infection, aspiration, fat embolism or ARDS) • Subpleural sparing: there may be an outer 1–2 mm rim of uniformly non-opacified subpleural lung (this is because blood is forced out of the subpleural tissues at the moment of impact)
Chest trauma
CHEST WALL AND LUNG TRAUMA
CHEST WALL AND LUNG TRAUMA
Rib fractures
additional lateral or oblique views are inappropriate in an acute trauma patient – the main priority is to detect complications such as a pneumothorax, haemothorax, or a pulmonary contusion
further imaging of these organs is mandatory
there can therefore be significant intrathoracic injury without an associated rib fracture
Multiple fractures (particularly of the posterior ribs) should raise the possibility of non-accidental injury
Pneumothorax
it can result from a pulmonary laceration from a fractured rib fragment or due to a sudden rise in intra-alveolar pressure 
detection is important as a small pneumothorax can rapidly increase in size with positive-pressure ventilation
Pulmonary contusion
‘contre-coup’ injuries can be seen
CXR/CT
diagnosis is made on a lateral CXR or CT
around ⅓ will have associated spinal cord injuries with a neurological deficit
these are usually small (2–5cm) and typically resolve over a few months
the lung herniates through a defect caused by either rib fractures or shoulder girdle dislocation 
most are treated conservatively
there is delayed development of poorly defined opacities at 48 
