Orbital blow-out fracture

The image illustrates the mechanism of an orbital blow-out fracture. The bony orbit is composed of thickened orbital rims (margins) but relatively thin inner walls. The zygoma and maxilla form the greater part of the medial, inferior and lateral orbital margins as well as almost all of the orbital floor.

ZMC fractures nearly always incorporate some degree of orbital fracture which become clinically relevant to the EM physician when they involve the orbital floor.

In an orbital blow-out fracture, the pressure from a direct blow involving the relatively tough globe is transmitted downwards, fracturing the floor of the orbit, and often results in herniation of intraocular contents into the maxillary sinus.

Learning bite

In blunt injuries involving the eye, the globe is more resistant to perforation than the bony orbit is to fracture.

Nasal bone fracture

The nasal bones are easily fractured due to them being broad and flat, but proximal nasal bone fracture may be accompanied by fractures of adjacent bones which may lead to additional complications such as:

  • CSF rhinorrhoea from involvement of the cribriform plate of the ethmoid bone
  • Orbital emphysema from fracture of the orbital plate (lamina papyracea) of the ethmoid

Learning bite

Although most nasal fractures are common and relatively benign, involvement of adjacent structures may produce significant complications.