Blowout orbital floor fracture

Key points

Definition: Blowout orbital floor fractures (BOFFs) result from direct trauma to the orbit transmitting force to the globe. This causes the orbital contents to “blow out” through the path of least resistance, usually the paper-thin lamina papyracea or the orbital floor.
Synonym: Internal orbital fracture.
Classic clue: Bowing or displacement of the inferior orbital wall in a patient with known or presumed facial trauma and soft tissue density in the adjacent maxillary sinus. Some patients show enophthalmos, restrictive strabismus, or infraorbital numbness.
Blowout orbital fractures (BOFs) may involve the orbital floor, medial orbital wall, or rarely the orbital roof, while sparing the orbital rim.
There are two generally accepted theories for the development of BOFs: the hydraulic and buckling theories.
While some patients with BOFs can give a clear history, like being struck in the eye with a baseball, many patients from inner city areas who present to the emergency department are less clear about the etiology.
Trauma to the orbit may occur in isolation or as part of a more generalized traumatic event. In the latter case, patients frequently have other facial fractures, most often involving the nasal bones.
Patients who present with orbital trauma may not give a clear trauma history, either because of posttraumatic neurologic sequelae or because of something they imbibed or injected previously.

Computed tomography (CT) is the imaging study of choice in patients with orbital trauma.
It may be necessary to add CT of the face and/or orbits to the imaging protocol if only brain CT is requested.
The use of plain films for the diagnosis of orbital trauma should probably be reserved for those cases where CT is unavailable.

May find fracture involving the bony cortex with or without displacement.
May see soft tissue mass extending into the roof of the adjacent maxillary sinus.
Herniated orbital contents usually contain orbital fat.
May have complete or partial opacification of the adjacent maxillary sinus as a result of hemorrhage and edema.
Herniation or entrapment of the extraocular muscles may cause limited ocular motion.
New fractures may cause associated fluid and/or air-fluid levels in the maxillary sinus.
May see intraorbital air and/or air-fluid levels.
Multiplanar imaging is most helpful with axial, coronal, and sagittal views. Three-dimensional imaging is helpful and popular with clinicians.
BOFFs are usually unilateral.

“Black eyebrow sign” is secondary to intraorbital emphysema caused by BOFs. This sign may be helpful to less experienced radiologists trying to interpret orbital plain films.
Plain films are of limited value for orbital imaging, and CT should be recommended.

Most patients present to the emergency department with a history of known trauma to the face or orbit or with a history of suspected trauma to the head and face but are “not really sure” what happened.
The majority of the fractures are secondary to personal altercations. The more complex fractures, however, are often related to a motor vehicle accident or a fall.
Associated clinical findings may include:
- Pain and tenderness.
- Enophthalmos.
  - May not be apparent until the initial swelling subsides.
- Diplopia on upward gaze.
  - Entrapment of the inferior rectus and occasionally of the inferior oblique muscles.
  - While muscular entrapment is less common than previously thought, it is now believed that herniation of fat and connective tissue may nevertheless tether the inferior rectus, causing restriction of upward gaze.
  - May be caused by rectus muscle hematoma .
  - Injury to a branch of the oculomotor nerve (CN III) may restrict upward gaze
- Orbital emphysema.
- Facial paresthesia secondary to infraorbital nerve entrapment or damage.
- Patient feels orbital pressure when blowing nose.
- Epistaxis.
  - Concomitant nasal fractures in more than 50% of cases.

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