Blow-Out Fracture



  • Defined as an orbital floor fracture that results from sudden blunt trauma to the globe:
    • Typically caused by the force of a projectile > half the size of the fist
    • Force transmitted through the noncompressible structures of the glove to the weakest structural point, the orbital floor, causing it to “blow out”
  • Orbital floor serves as roof to air-filled maxillary and ethmoid sinuses:
    • Communication between the spaces results in orbital emphysema
  • Orbit contains fat, which holds the globe in place:
    • Orbital floor fracture may result in herniation of the fat on the inferior orbital surface into the maxillary or ethmoid sinuses
    • Leads to enophthalmos owing to orbital volume loss and sinus congestion; fluid collection may occur secondary to edema and bleeding
  • Infraorbital nerve runs through the bony canal 3 mm below the orbital floor:
    • Injury may result in hypoesthesia of the ipsilateral cheek and upper lip
    • To distinguish facial hypoesthesia related to local swelling from nerve injury: Test for sensation on the ipsilateral gingiva, which is within the infraorbital nerve distribution
  • Inferior rectus and the inferior oblique muscle run along the orbital floor:
    • Restriction of these extraocular muscles may occur because of entrapment within the fracture, contusion, or cranial nerve dysfunction
    • Typically manifests as diplopia on upward gaze
    • Inability to elevate the affected eye normally on exam
  • Medial rectus located above the ethmoid sinus:
    • Less commonly entrapped
    • Diplopia on ipsilateral lateral gaze


Caused by a projectile that strikes the globe. The force is transmitted through the noncompressible structures of the globe to the weakest structural point, the orbital floor resulting in a blow-out fracture
Pediatric Considerations
  • Orbital roof fractures with associated CNS injuries more common in children
  • Orbital floor fractures: Unlikely before 7 yr of age:
    • Orbital floor is not as weak a point in the orbit due to lack of pneumatization of the paranasal sinuses
  • Unfortunately fractures can occur in children and may result in unrecognized entrapment of the rectus muscle labeled the “white-eyed” fracture:
    • Findings are subtle and there may be little associated soft tissue injury
    • These children may present with marked nausea, vomiting, bradycardia, headache, and irritability suggestive of a head injury that commonly distracts from the true diagnosis

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