What radiographic findings on an orbital X-ray suggest a fracture?

Radiographic Findings on Orbital X-ray Suggestive of Fracture

CT is the most useful imaging modality for evaluating orbital trauma and is the most accurate method for detecting orbital fractures, as plain radiographs are insufficient for detecting orbital pathology in trauma cases. 1

Key Radiographic Findings on Orbital X-ray

While CT is preferred, when orbital X-rays are used, the following findings may suggest fracture:

Orbital Line Changes

• Discontinuity or irregularity of orbital lines, including:
  • Posterior lamina papyracea line (PLPL) - most commonly shows depression or loss (88.7% sensitivity for lamina papyracea fractures) 2
  • Inferomedial orbital line (IMOL) - may show depression, loss, or discontinuity 2
  • Anterior lamina papyracea line (ALPL) - may show changes in medial wall fractures 2
  • Posteromedial floor line (PMFL) - changes visible in floor fractures 2
  • Inferior wall line - changes visible in orbital floor fractures 2

Other X-ray Findings

• Asymmetric focal soft tissue density 2
• Orbital emphysema (air in orbital tissues) 3
• Orbital hematoma 3
• Herniated orbital fat into paranasal sinuses 3
• Comminuted/unhinged, hinged, or linear fracture patterns 3

Clinical Context and Imaging Recommendations

When to Suspect Orbital Fracture

• Periorbital soft tissue swelling and ecchymosis
• Subconjunctival hemorrhage
• Diplopia or restriction of ocular movement
• Vision loss
• Hypoglobus (downward displacement of the eye)
• Enophthalmos (posterior displacement of the eye) 1

Recommended Imaging Approach

1. CT Orbits (without contrast) is the gold standard:

   • Provides accurate detection of fractures
   • Identifies soft tissue injuries (globe, extraocular muscles)
   • Detects hemorrhage and foreign bodies (94.9% sensitive for intraorbital foreign bodies) 1
   • Thin-section orbital CT with multiplanar reconstructions is optimal 1

2. MRI Orbits as a supplementary modality:

   • Superior soft tissue contrast for evaluating globe and optic nerves
   • Better for detecting non-metallic foreign bodies (especially wooden objects that may appear as air on CT) 1
   • Contraindicated if metallic foreign body is suspected 1

3. Plain Radiography has limited utility:

   • Insufficient for comprehensive detection of orbital trauma 1
   • May have role as screening for metallic foreign bodies 1
   • Orbital lines on plain radiographs can help detect blow-out fractures with 85.7-100% sensitivity depending on fracture location 2

Risk Factors for Serious Ocular Injury with Orbital Fracture

Five variables associated with increased risk of substantial ocular injury in orbital fracture:

• Blunt trauma with a foreign object
• Inability to count fingers
• Roof fracture
• Diplopia on primary gaze
• Conjunctival hemorrhage or chemosis 4

Important Considerations

• Orbital floor fractures are most common in older children and adults, while orbital roof fractures are more common in children <8 years 1
• Trap door orbital fractures can cause entrapment of extraocular muscles or orbital contents, leading to restricted movement and diplopia 1
• Incarceration of the inferior rectus muscle within a trap door fracture may rapidly result in ischemic injury and subsequent restrictive strabismus 1
• Diplopia does not always indicate muscle entrapment, as it can also result from soft tissue swelling, hematoma, or nerve paresis 1

Remember that while X-rays may provide some information, they have been largely replaced by CT in current clinical practice for orbital trauma evaluation.