Orbital burst fractures and types

  Orbital burst fracture is the most common type of orbital fracture and ranks second after nasal trauma in all facial trauma.  When the orbital opening is larger than the orbital cavity, the orbital ball becomes lodged in the orbit, compressing the orbital contents and causing a sharp increase in orbital pressure, which in turn causes herniation of orbital tissue through the weak infraorbital wall into the maxillary sinus, which is usually embedded in the fracture area because the orbital tissue retracts less rapidly than the orbital bone, i.e., an orbital burst fracture.  The most classic orbital burst fracture is a low-energy fracture located in the medial half of the inferior orbital wall to the infraorbital sulcus, which is the weakest area of the infraorbital wall and therefore the most common, accounting for approximately 50% of fractures.  The second type of orbital burst fracture is a fracture of the infraorbital wall involving the infraorbital sulcus in the medial hemisphere.  The third type is a fracture of the infraorbital wall in conjunction with the infraorbital wall, which can be caused by moderate energy and accounts for about 20%-40% of orbital burst fractures, and is the runner-up to orbital burst fractures.  The fourth type of orbital burst fracture is the total orbital floor fracture, which is most typically caused by a violent shear force acting on the lateral aspect of the inferior orbital sulcus causing a fracture of the entire orbital floor. Total orbital floor fractures include teetotallic fractures, comminuted fractures, and open-window fractures.  The fifth type of orbital burst fracture is the atypical burst orbital fracture, which includes rectangular fractures, triangular fractures, and star-shaped fractures.  The sixth type is linear fractures of the orbital floor without displacement of the fracture fragments, including Y-shaped fractures and lateral linear fractures.