Surgeons care about 2 things: form and function

• Does the fx cause a significant cosmetic deformity that requires repair (form)?

• Does fx pattern cause injury to an adjacent anatomic structure that disrupts normal function and creates sx for the patient (function)?

Treating surgeons need to restore normal facial contour and thus need to know which key articulations and buttresses have been disrupted and need to be carefully realigned. 

Buttress anatomy

• Horizontal: 

  • Upper transverse (orbital floor)

  • Lower transverse maxillary (palate)

  • Upper transverse mandibular

  • Lower transverse mandibular

• Vertical: 

  • Medial maxillary (medial orbital wall)

  • Lateral maxillary (lateral orbital wall)

  • Posterior maxillary (pterygomaxillary)

  • Posterior vertical

• High impact fx: supraorbital rim, mandibular symphysis, frontoglabellar, mandibular angle.

• Low impact fx: zygoma, nasal bones

Traumatic deformity of orbital floor (MC) OR medial wall resulting from impact of blunt object larger than orbital aperture

Types:

• Pure w/o orbital rim fx / Blowout fx: involves orbital wall but spares orbital rim and expands orbital volume.

  • Orbital floor blowout (MC)

    • Trapdoor fx: special type of floor blowout that usually occurs in children where the inferiorly displaced fx fragment recoils and entraps herniated orbital ST, which can cause restricted motility or necrosis of the inferior rectus mm.

  • Medial orbital wall blowout

• Impure w/ orbital rim fx

2 broad categories:

• Open door: large displaced frequently comminuted

• Trapdoor: linear, hinged, minimally displaced

Associated findings

• Herniation of orbital contents

• Involvement of infraorbital canal

• Oribital ST injury

• Orbital emphysema can have mass effect -> compression/stretch of optic nerve insertion w/ tenting of globe.

• Can involve combo injury with nasal, LE fort, ZMC

Large orbital blowouts (>2 cm defect area or >1.5 mL outward herniated volume) predicts development of noticeable enophthalmos after acute swelling subsides.

Report:

• Entrapment is a clinical diagnosis. Must note position, orientation and configuration of EOMs as functional entrapment can occur without significant displacement.

• Check for mass effect on optic nerve insertion from retrobulbar hematoma or emphysema

3 types, all of which involve the pterygomaxillary buttress (pterygoid plates) which results in detachment of the maxillary occlusion-bearing segment (palate, alveolus, and maxillary teeth) from the skull base (pterygomaxillary disjunction) and results in varying degrees of midface detachment depending on severity of injury.

• Type 1: lateral margin of pyriform (nasal) aperture (inferior orbital rim and zygomatic arch intact) -> free movement of hard palate (floating palate)

• Type 2: pyramidal fx involving the inferior orbital rim, orbital floor and medial orbital wall -> free movement of nose and hard palate (floating maxilla)

• Type 3: zygomatic arch, lateral and medial orbital walls -> free movement of entire midface (craniofacial dissociation)

Non-occlusion related components of the upper level Le Fort fx's can be treated as combinations of NOE, ZMC and/or orbital fx. However, reporting Le Fort 2 or 3 is important for Denver screening criteria for blunt cerebrovascular injury (need to order CTA H&N to look at neck arteries and CoW)

• Tooth fx are classified by what is involved: Crown, Root, or both.

  • Crown fx are categorized by involved layers: enamel-only, enamel-dentin, or enamel-dentin-pulp

• Partial axial displacement of a tooth may be...

  • directed out of its socket = extrusive luxation (loosening)

  • directed into its socket = intrusive luxation

• Avulsion =  complete displacement out of the socket.

• Alveolar process fx: can spare or involve the socket and allow eccentric displacement of a tooth from its socket, which is called lateral luxation.

• Nondisplaced tooth fx can be seen as a linear area of low attenuation traversing the tooth.

• Tooth avulsion or luxation can be associated w socket fx and seen as widening of the periodontal ligament space; most commonly affects the central incisors in children 7-14 yo. Early dx while the periodontal ligament cells are still viable allow for early tooth reimplantation.