Orbital Floor Fracture (Blowout Fracture)

Risk factors

• Blunt facial or periorbital trauma (fist, ball, vehicle airbag, etc.)
• Adult age 20-40 most common
• Pediatric age (greenstick, trapdoor)
• Osteopenia, prior orbital surgery

Pathophysiology

Two mechanisms are proposed: hydraulic theory — an object larger than the orbital rim strikes the globe, transmitting force to the thin orbital floor (maxillary roof) which then fractures; and buckling theory — direct force on the rim transmits a buckling wave to the floor. Either way, the relatively thin floor or medial wall fractures into the maxillary or ethmoid sinus, allowing fat and possibly the inferior rectus or inferior oblique to herniate or become entrapped. In children, the elastic bone may snap shut over the entrapped tissue (trapdoor), causing severe motility restriction with minimal external swelling — the 'white-eyed blowout fracture.'

Clinical presentation

Differential diagnosis

• Isolated soft tissue periorbital trauma — Ecchymosis, swelling without restriction of EOM, intact globe, no enophthalmos; CT negative
• Zygomaticomaxillary complex (tripod) fracture — Involves zygomaticofrontal, zygomaticomaxillary, and zygomatic arch; rim step-off; flattening of cheek
• Le Fort fractures — Midfacial mobility, malocclusion; severe high-energy trauma
• Globe rupture / open globe injury — Teardrop pupil, soft globe, decreased vision; protect first
• Retrobulbar hemorrhage — Proptosis, decreased vision, elevated IOP, tense lids; orbital compartment syndrome; emergent canthotomy/cantholysis
• Traumatic optic neuropathy — Decreased vision and RAPD after trauma without globe rupture; imaging may show canal fracture
• Cranial nerve palsy from head trauma — Restricted EOM with normal CT orbit; consider intracranial injury

Diagnostic workup

Diagnostic algorithm

flowchart TD
  A[Periorbital trauma] --> B[Visual acuity,<br/>pupils, EOM,<br/>slit lamp,<br/>infraorbital sensation]
  B --> C{Open globe<br/>or retrobulbar<br/>hemorrhage?}
  C -->|Yes| D[Treat first<br/>shield / canthotomy]
  C -->|No| E[CT orbits/face<br/>without contrast]
  E --> F{Findings?}
  F -->|Trapdoor with<br/>muscle entrapment<br/>(pediatric or adult,<br/>oculocardiac reflex)| G[Urgent surgery<br/>≤24-48 h]
  F -->|Large fracture<br/>OR persistent diplopia<br/>OR enophthalmos >2 mm| H[Surgery<br/>within 1-2 weeks]
  F -->|Small fracture<br/>no entrapment| I[Observation:<br/>ice, no nose blow,<br/>oral antibiotic ± decongestant,<br/>reassess 1-2 wk]
  G --> J[Counsel on nose-blowing<br/>and follow-up]
  H --> J
  I --> J

Treatment

Complications

• Persistent diplopia and motility restriction
• Enophthalmos (often delayed, after orbital edema resolves)
• Infraorbital nerve hypesthesia (often improves over weeks to months)
• Orbital emphysema with elevated IOP if patient blows nose
• Sinus complications (sinusitis, oroantral fistula)
• Globe injury (hyphema, retinal injury, optic neuropathy) — must be excluded
• Implant infection or extrusion, lower lid malposition, ectropion after surgery
• Trapdoor with prolonged entrapment can cause ischemic necrosis of the inferior rectus and permanent motility loss

PANCE pearls

• ALWAYS examine the globe and vision before focusing on the fracture — exclude open globe, hyphema, retinal injury, and retrobulbar hemorrhage.
• Infraorbital numbness is the most consistent symptom of an orbital floor fracture.
• Pediatric 'white-eyed blowout' is a SURGICAL EMERGENCY — minimal external signs but mechanical entrapment; delay risks permanent muscle necrosis.
• Counsel ALL patients with orbital floor fractures NOT to blow their nose for 2 weeks.
• Most adult fractures without entrapment or significant enophthalmos can be observed for 1-2 weeks and then reassessed.
• Retrobulbar hemorrhage with proptosis, decreased vision, and elevated IOP after trauma demands immediate lateral canthotomy and cantholysis at the bedside.

References

• AAO PPP — American Academy of Ophthalmology Preferred Practice Pattern: Eye Trauma (orbital fractures section)
• AAO-HNS — American Academy of Otolaryngology-Head and Neck Surgery resources on facial fractures
• AAOMS — American Association of Oral and Maxillofacial Surgeons clinical guidelines on orbital and midface fractures