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CT of Maxillofacial Injuries

Stuart E. Mirvis, M.D., FACRDepartment of Radiology

University of Maryland School of Medicine

Viking 1 1976 MGS 2001

Technology changes the diagnosis

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Technologic Evolution

Struts and buttresses

Topics to Cover

Orbital fracturesNaso-orbital ethmoid (NOE)Zygomaticomaxillary complex – (ZMC)Le Fort midface patternsOcularOcularMandibleBoom!

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Facial StrutsFacial Struts Posterior coronal strutsconsisting of posterior wall of maxillarysinus (1) and pterygoid plates (2)

Anterior coronal struts consisting of frontal (1 ), zygomaticofrontal (2), nasofrontal (3), anterior maxillary (4), anterior alveolar (5) components. 

Sagittal struts consisting of median (1 ), parasagittal(2), and lateral (3) parts

Horizontal struts superior (1), middle (2),and inferior (3) parts. 

Gentry LR, et al. High-Resolution CT Analysis of Facial Struts in Trauma: 1. Normal Anatomy. AJR 140:523-532, March 1983

Concept of Facial ButtressesConcept of Facial Buttresses

Major support for facial skeleton to maintain form and function (I‐beams)maintain form and function (I‐beams)

Attach directly or indirectly to skull base or cranium

3 vertical and 3 horizontal

Buttresses accommodate screw fixation

Maintain facial width and height

Establish functional support (orbits and teeth)

Hopper RA, Salemy S, Sze RW. Diagnosis of MidfaceFractures with CT: What the Surgeon Needs to Know. RadioGraphics 2006; 26:783–793

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Highlights of Facial Anatomy - Orbit

Orbital sutures and thin orbital bony plates allow suture diastasis and fractures of thin bone to absorb

impacting energy.

This mechanism plus orbital fat and muscles cushions the globe and preserves vision in high-energy

impacts to the orbit.

Orbital BlowOrbital Blow--out Fractures:out Fractures:Significant Imaging FeaturesSignificant Imaging Features

E id f l f t t t ( iti / h fEvidence of muscle or fat entrapment  (position/shape of muscle)Pure or impure fracture (?intact inferior orbit rim)Orbital hematoma (up to 24% orbital injuries)Complications: enopthalmous, diplopia, hypoesthesia Size (area) of floor defect or associated fracturesCalculations of blow‐out fractures of the orbital floor by 3D‐CTCalculations of blow‐out fractures of the orbital floor by 3D‐CT 

and 2D‐CT method are accurate for assessing the area of fracture and the volume of herniated tissue*

*Ploder O, 2D- and 3D-based measurements of orbital floor fractures from CT scans. J Craniomaxillofac Surg. 2002

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Orbital blow-out fracture

Orbit BlowOrbit Blow--out Fractureout Fracture

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Herniated Inferior Rectus

Orbit Blow-out Fracture

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Medial orbital wall fracture

Isolated or associated 20-40% with floorIsolated or associated 20 40% with floor fracture

More common to cause orbital emphysema

Rarely surgically repaired

Complications: Horizontal gaze palsy, enopthalmous, epistaxis

Medial Medial Orbital Orbital

BlowBlow--out out FracturesFractures

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Medial wall fracture -entrapment

Medial blow-out with herniation

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Orbital Blow-in fracture

Orbital Blow-in fracture: MRI with brain herniation

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Orbital Blow-up fracture

RareRare

Orbital roof fragments explode into frontal lobe

Typical – dural tears and CSF leak

Frontal sinus involvement commonFrontal sinus involvement common

Orbital “blow-up” fracture

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Orbital Blow-up fracture

Naso-orbital-ethmoid Complex

Nasal bridge, lower frontal sinus, medial orbits

Comminution, depression, and lateral spread of bones

Soft tissue injury; medial canthal ligament, lacrimal drainage nasofrontal sin sdrainage, nasofrontal sinus

Usually associated fracture patterns

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Naso-orbital Ethmoid Fractures

N= 21N= 21Clinical findings:

Widened intercanthal distance (71%)Increased nasofrontal angle (28%)Epistaxis (100%) Visual disorder (62%)Visual disorder (62%)Cerebrospinal rhinorrhea (33%) Enophthalmos (23%)Facial paralysis (14%)

Naso-orbital-ethmoid Complex

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Naso-orbital-ethmoid Complex

NOE and repair

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NasomaxillaryFracture

Kicked by horse

Sagittal mid-face pattern

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Zygomatic-maxillary Complex (ZMC)

Impact on malar eminence

4- point fracture

Displaces posterior and medially

Simple type vs hi-gradeSimple type vs. hi-grade variant

Zygomatic-maxillary Complex

(ZMC)

Al i lAlways involves orbital floor

May involve medial orbit wall

Lateral canthal ligamant and inferiorligamant and inferior orbital nerve

Coronoid process impact

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Zygomatic-maxillary Complex (ZMC) –

hi-grade

Zygomatic-maxillary Complex (ZMC) Hi-grade

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Complex ZMC

yOrbital Apex Syndrome

Optic neuropathy and ophthalmoplegiaOptic neuropathy and ophthalmoplegiaLoss of cranial nerves II, III, IV, opthalmic division of V, and VI Blindness, fixed dilated pupils, proptosis, ptosisC i fl t i f ti l tiCauses: inflammatory, infectious neoplastic, iatrogenic/traumatic, and vascular conditions

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LeFortLeFort Fracture PatternsFracture PatternsDescribed as symmetric mid‐face lines of weakness ‐

experimental

Often asymmetric clinically and combined with ZMC, NOE

Al i l t id l t f tAlways involves pterygoid plate fractures

Higher energy usually leads to higher grade

Any pattern of Lefort 1,2,3 fractures can occur

In 1901 the French surgeon, Dr. Rene LeFort (1869-1951), French army surgeon from Lille, published his results from pexperiments aimed to describe fracture patterns. He performed a number of experiments on cadaver heads. These experiments included blows to the cadaver head at different angles with a wooden club. He also hurtled the head against stationary objects and kicked it in various places in the face

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LeFort Fracture Patterns

LeFortLeFortFracture 1Fracture 1

Fracture all 6 walls of maxillary sinuses

Floating palate

Typically: nasal septum & maxillary

l inasal spine

Airway compromise -rare

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LeFort Fracture I +

LeFortLeFort II Fracture PatternsII Fracture PatternsMobile nose and maxilla (a portion of the upper 

transverse maxillary buttress [orbital rim] is involved in mobile segment)Fx.  Lateral maxillary sinus, medial orbital floor, 

nasal bridge, pterygoids (pyramidal)g , p yg (py )

Soft tissues: medial orbit, infraorbital nerve

ZygomaticomaxillaryFrontomaxillary

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LeFort 2

LefortLefort II and II and NOENOE

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Unilateral Unilateral LeFortLeFort 2/32/3

LeFort Fracture III

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LeFort Fracture III

Lefort II/III: highly comminuted

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Combined LeFort Fracture Pattern - Smash

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GSW through the medial orbit – monocular

blindness

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Mandibular Fractures

Fracture Type Prevalence

Mandibular Fractures

Body 30 - 40 %

Angle 25 - 31 %

Condyle 15 - 17 %

Symphysis 7 - 15 %

Ramus 3 - 9 %

Al l 2 4 %Alveolar 2 - 4 %

Coronoid process 1 - 2 %

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Mandibular Angle Fracture

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ORIF angle/body fx –oops!

Mandibular Fracture – Dislocation

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Mandibular Fracture - Dislocation

Mandible fracture-

dislocation (sagittal split)

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LeFort I/II/III: Comminuted mandible fractures

Bilateral TMJ dislocation - yawning

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Attempted suicide: Bit blasting cap

GSW: Facial explosion

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Fibular graft reconstitutingreconstituting

maxillary contour