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Orbital Blowout Fracture

URGENT — Trauma

Symptoms

  • pain with eye movement and local orbital tenderness
  • binocular diplopia (resolves when one eye is covered)
  • eyelid edema, ecchymosis, and periorbital swelling
  • crepitus (crackling) after nose blowing (orbital emphysema)
  • numbness of the cheek, upper lip, or teeth (v2 distribution)
  • nausea or vomiting (suggests oculocardiac reflex)

Clinical Findings

Clinical exam

  • infraorbital nerve (v2) hypesthesia: highly specific for floor fractures
  • restricted motility: most common in upgaze (inferior rectus) or lateral gaze
  • enophthalmos (sunken eye) or hypoglobus: may be masked by initial swelling
  • palpable orbital rim step-off deformities

Pediatric specialty

  • white-eyed blowout fracture (webof): minimal external bruising but severe muscle entrapment
  • oculocardiac reflex: bradycardia, nausea, and syncope (surgical emergency)

Associated injuries

  • always screen for globe rupture, hyphema, commotio retinae, and retrobulbar hemorrhage

Etiology

Mechanism

  • blunt trauma (e.g., fist, ball, airbag) transmits pressure to the thin orbital walls
  • orbital floor (maxilla) and medial wall (ethmoid) are the most frequent sites

Entrapment

  • herniated orbital fat or extraocular muscles become "snagged" in the fracture site
  • pediatric "trapdoor" effect: flexible bone snaps back, incarcerating the muscle

Red Flags

  • pediatric trapdoor fracture: requires emergent repair (24–48h) to prevent muscle ischemia
  • retrobulbar hemorrhage: signs include proptosis, tight lids, and increased iop; requires lateral canthotomy
  • rapd or sudden vision loss: suggests traumatic optic neuropathy or compartment syndrome

Investigations

Imaging (mandatory)

  • ct orbits + midface (1mm cuts, no contrast): coronal views are best for the floor

Clinical testing

  • forced duction test: used to distinguish mechanical entrapment from muscle edema/palsy
  • sensation testing: compare cheek and upper lip sensation bilaterally
  • cardiac monitoring: check for bradycardia in symptomatic children

Treatment

Acute phase

  • head elevation, cold compresses, and nasal decongestants (e.g., oxymetazoline)
  • prophylactic antibiotics (e.g., amoxicillin/clavulanate) if sinusitis is present

Surgery (immediate - 24–48h)

  • indicated for pediatric trapdoor fractures with oculocardiac reflex or muscle incarceration

Surgery (delayed - 1–2 weeks)

  • indicated for persistent symptomatic diplopia, enophthalmos ≥2mm, or floor fracture >50%

Clinical Pearl

in a child with a blowout fracture, a "quiet" eye with vertical restriction and bradycardia/nausea is the trapdoor sign — operate within 24–48 hours to save the inferior rectus.

Differential Diagnosis

  • • orbital edema and hemorrhage (no fracture)
  • • cranial nerve palsy (iii, iv, or vi)
  • • retrobulbar hemorrhage (orbital compartment syndrome)
  • • traumatic optic neuropathy

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