Imaging Of Facial Trauma Part 3 (2) 2

Imaging of Facial Trauma Part 3: Pathology

(Zygomatic, Maxillary and Mandibular Fractures) Rathachai Kaewlai, MD

www.RadiologyInThai.com

Created: January 2007

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Outline

Facial and mandibular fractures Nasal fractures Naso-orbital-ethmoidal fractures Frontal sinus fractures Orbital fractures Zygomatic fractures Maxillary fractures Mandibular fractures

Imaging approach

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Zygomatic Fractures

Two types of zygomatic fractures Zygomatic complex fracture

Isolated zygomatic arch fracture

Relevant anatomy

Malar eminence = surface anatomy of the body of zygoma

Zygomatic fractures can cause limitation of mandibular motion, especially when fractures are depressed Masseter muscle arises from zygomatic arch

Coronoid process is located underneath the zygomatic arch

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Zygomatic Fractures

Zygomatic complex fractures AKA ZMC fracture, trimalar fracture, malar eminence fracture Tripod fracture is a misnomer (zygoma actually has 2 attachments

to cranium and 2 to maxilla) Principal lines involve 3 components

Orbital process of zygoma Inferior rim of orbit Zygomatic arch

Main fragment is zygoma, which is separated from its three areas of attachment

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Zygomatic Fractures

Zygomatic complex fractures Fractures almost invariably traverse the infraorbital nerve foramen

(located in the orbital floor), causing impaired sensation of the cheek and a portion of the upper lip. However in majority of cases, the nerve is usually intact

Image interpretation should pay additional attention to Alignment of zygoma (depressed, rotated) Lateral orbital wall alignment (posterior relationship of zygoma and

sphenoid bones) Angulation of the wall results in increased orbital volume and

enophthalmos

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Zygomatic Fractures

Isolated zygomatic arch fracture Etiology: direct blow by small object

Commonly consists of 3 fracture lines: One at each end and the third in the center with depression of

fracture fragment

Limited motion of mandible may occur if the fracture impinges on coronoid process or simply because the masseter muscle arises from zygomatic arch

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Zygomatic Complex Fractures

60-year-old man fell onto the left cheek. Axial and coronal reformatted CT images show typical left ZMC fractures: anterior/posterior walls of maxillary sinus including rim (red arrows), zygomatic arch (green arrow), and orbital process of zygoma (blue arrow). Left orbital floor ‘blow-out’ fracture with intraorbital fat herniation is seen in coronal image. Orbital floor fracture is commonly associated with ZMC fractures.

H = Hemosinus, = Soft tissue emphysema due to communication with fractured sinus

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Zygomatic Complex Fractures

Same patient as in the previous page

3D image shows all components of left ZMC fractures including the inferior orbital rim (red arrows), zygomatico-frontal separation (blue arrow), zygomatic arch (green arrow).

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Isolated Zygomatic Arch Fractures

23-year-old man was punched by a left-handed. Classic zygomatic arch fractures occur in three sites along the arch. The middle fracture causes fracture fragment depression.

Maxillary Fractures

Types of maxillary fractures Maxillary sagittal fracture (maxillary sinus fracture)

Palate fracture

Alveolar process fracture

LeFort fractures LeFort I fracture

LeFort II fracture

LeFort III fracture

Combination (bilateral, hemi-)

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Maxillary Fractures

Maxillary sagittal fracture AKA maxillary sinus fracture

Fracture of a maxilla in sagittal plane, involving anterior-lateral wall of a maxillary sinus (LeFort fractures represent bilateral maxillary fractures)

Due to direct blow to either right or left midface

Plain film shows opacified maxillary sinus, however it is usually inadequate for diagnosis

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Maxillary Sagittal Fracture

68-year-old man was found down.

There is a sagittal plane fracture of the left maxillary sinus (red arrow) with hemosinus (H)

Maxillary Fractures

Isolated alveolar process fracture Fracture of any portion of the alveolar process

Clinically evident by malalignment and displacement of teeth contained within fractured segment

Even on CT, fracture may be subtle and easily overlooked

Further imaging may be needed when the diagnosis is made X-ray of the teeth or a panoramic view (look for dental injuries)

Chest radiograph (look for aspirated teeth)

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Maxillary Alveolar Process Fractures

Middle age women fell onto her mouth. Red arrows show the comminuted fractures of the maxillary alveolar process on the right side. These fractures are considered ‘open’ as they are connected to the oral cavity.

LeFort Fractures

Among the most severe fractures seen in face and associated with high-energy trauma

Named after René LeFort, a French physician, who studied facial fractures in cadavers. Result was published in 1901

Key facts In each type, there is a partial or complete separation of maxilla from

the remainder of the facial skeleton All LeFort fractures must extend through posterior face, transects the

pterygoid processes Any combination of LeFort I, II, and III patterns can occur

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LeFort Fractures

LeFort I fracture Definition: transmaxillary fracture

Transverse (horizontal) fracture of inferior maxillae, involving maxillary sinuses (all except superior walls), lateral margin of nasal fossa, nasal septum and pterygoid plates

Clinical: free floating and movable hard palate with maxillary teeth

Imaging findings Opacified bilateral maxillary sinuses

Transverse fracture through the inferior maxillae above hard palate

Best shown and confirmed by coronal and sagittal reformatted CT images

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LeFort I Fracture

48-year-old man was kicked by a horse. LeFort I fracture line along bilateral maxillary sinuses (red arrows). Pterygoid plate fractures are not shown H = Hemosinus, Blue arrow = Mandibular fracture

LeFort Fractures

LeFort II fracture Pyramid-shaped maxillary fracture, involving maxillary sinuses

(anterior-lateral walls), inferior orbital rim, orbital floor and nasofrontal suture

Clinical: free floating, movable midface including maxillary teeth, hard palate and nose

Imaging findings: Opacified bilateral maxillary sinuses and orbital emphysema

Fractures of anterior/lateral walls of maxillary sinuses, inferior orbital rims/floors and disruption of nasofrontal suture

Best seen and confirmed by coronal reformatted CT images

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LeFort II Fracture

Middle age man in motor vehicle accident. Fracture lines are demonstrated in red arrows. Fracture of pterygoid plates are present in all type of LeFort fractures.

H = Hemosinus

LeFort Fractures

LeFort III fracture AKA craniofacial disjunction This fracture separates calvaria (skull) from the facial bones. Most severe

of all LeFort fractures Definition: separation of facial bones from the skull

Zygomas separated from sphenoid at zygomatico-sphenoid sutures

Nasal bones and medial orbital walls separated from frontal bone at nasofrontal sutures

Best seen in coronal images

Clinical: movement of face relative to the skull Imaging findings:

Plain film will underestimate degree of injury due to severe soft tissue swelling obscuring the bony details. CT is recommended

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Combined LeFort II and III Fractures

32-year-old man, unrestrained driver in a motor vehicle accident.

Blue arrows define LeFort II fracture. Red arrows define the LeFort III fracture.

Mandibular Fractures

Motor vehicle collisions and assaults together account for more than 80% of mandible fractures

Incidence Ratio of mandibular to facial fractures = 2:1 Co-existence of mandibular and facial fractures = 6-10% Rare in children

If occurs, condyle is the most common location Condyle is the growth center of mandible. Trauma to this area can retard

growth and cause facial asymmetry

Clinical Laceration under chin (common) Pain, malocclusion, deviation of mandible on opening mouth

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Mandible is divided into region for purpose of describing location of fractures

Symphysis (= within the boundaries of central incisors) Parasymphysis (within the boundaries of vertical lines distal to canine

teeth) Body (include the region of third molar) Angle (distal to the third molar) Ramus Condylar process (has separate classification system) Coronoid process Alveolar process (region normally contains teeth)

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Relevant anatomy Mandible is a ring or arc bone which is usually difficult to break in

one location. Approximately half of mandible fractures occur in multiple locations. Search for a second fracture after initial fracture is identified!

(usually at contralateral side) In angle fracture: 3 muscles attaching to the ramus of mandible

(masseter, temporalis and medial pterygoid) pull the proximal fragment upward and medially

In symphyseal, parasymphyseal fractures: Digastric, geniohyoid and genioglossus muscles pull the symphysis downward posteriorly

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Imaging recommendation Plain film mandible series (PA, lateral, Towne’s and bilateral obliques)

show nearly all fractures BUT may be difficult to obtain in multi-trauma patients

Panoramic radiography (orthopantography) Need patient in upright position Better to look for subtle tooth fracture

CT Show all mandibular fractures AND other facial fractures (co-existence

6-10%), as well as position and alignment of fragments Display associated soft tissue injuries

Easy to perform in multi-trauma patient

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Bilateral Mandibular Fractures/Dislocations

Red arrows = Mandibular condyles which are located ‘too anterior’ than usual

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Bilateral Mandibular Fractures/Dislocations

Same patient as in previous page. CT shows left symphyseal/ parasymphyseal fracture extending to the tooth (green arrows), and bilateral mandibular condyle fractures (red arrows). The findings represent ‘Flail mandible’. Limitation of plain films in previous page is likely due to 1. Inadequate coverage (PA projection does not include the inferior part of mandible) 2. Suboptimal technique (Oblique views are not true oblique)

If plain film is to be used, make sure to have all projections, adequate coverage and optimal technique. If in doubt, CT is the solution

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43-year-old man, fell from height, presented with malocclusion Orthopantogram demonstrates a fracture of the right ramus of mandible (red arrows). Subtle ‘second’ site of fracture is at the left body (green arrows) which is confirmed in CT scan (next page).

Search for second site of fracture is warranted

when one sees mandibular fracture

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Right Sagittal


Same patient as in previous page. CT confirms the fractures of the right angle of mandible (red arrows) and left body (green arrows). Axial image shows extension of fracture into the root of the left mandibular tooth, indicating an open fracture

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21-year-old man was punched at his left face by the right-handed person. Orthopantogram shows a nondisplaced fracture of the left angle of mandible (red arrows), extending to the root of unerupted ADA #18.

Where is the second site of fracture?

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Same patient as previous page. CT Orthopantogram (post-processing images from axial CT) shows an additional nondisplaced fracture of the left parasymphysis (blue arrows).

Plain orthopantogram should not be used as a single imaging to look for mandibular fractures. It is useful for tooth fracture, not for mandible.

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Mandibular Fractures with TMJ Dislocation

19-year-old woman in a rollover motor vehicle accident. Axial CT image (A) shows ‘empty glenoid sign’ (red line) indicating right temporomandibular joint dislocation. Image B in a more inferior slice reveals a fracture of the right mandibular condyle (red arrow) with anterior medial displacement of the condyle due to the pull of lateral pterygoid muscle. The left glenoid fossa is normal.

C = Left condyle of mandible

A B

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Mandibular Fractures with TMJ

Dislocation

Same patient as in previous page.

3D image on right lateral view makes it easier to understand the fracture site, dislocation and orientation of the fragment.

Red arrows = fracture of the base of right condyle of mandible

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Mandibular Fractures with Tooth Fracture

Young man in a motor vehicle accident. Tooth fracture of ADA #29 is apparent (blue arrow) in this orthopantogram. However, fracture of the right body of mandible is very subtle (red arrow) and may be detected only retrospectively. This confirms that orthopantogram is not an appropriate imaging technique to rule out or characterize mandible fractures.

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Mandibular Fractures with Tooth Fracture

Same patient as in previous page. In this case, CT demonstrates comminuted fracture of the right body of mandible (red arrow) and tooth fracture (blue arrow).

Imaging Approach - Plain Film

Friendly line (anterolateral antral wall of maxillary sinus) Both intact

NO ZMC or LeFort fractures

Blowout fracture

Isolated fractures of lateral orbital wall, zygomatic arch

One disrupted ZMC fractures

Maxillary sagittal fracture (isolated sinus fracture)

Both disrupted LeFort fractures

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Imaging Approach - CT

Clear sinus sign (= all sinuses and mastoid are clear of fluid), there are three possible facial fractures: Nasal bone fractures

Isolated zygomatic arch fractures

Mandible fractures

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Imaging Approach - CT

Bloody sinuses Pterygoid plate fracture present - probable LeFort fracture

With fracture of lateral margin of nasal fossa = LeFort I

With fracture of inferior orbital rim = LeFort II

With fracture of zygomatic arch = LeFort III

Maxillary wall fractures

Orbital floors, NOE region fractures

ZMC fractures

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Checklist for Facial Radiograph/CT

Treat life-threatening injury first (ABC of trauma)

CT is more accurate, faster to do than plain films and can be performed at the same time as trauma head CT

Facial structures are quite symmetrical

Do not stop searching when see one abnormality

If suspect for more than simple nasal fracture, do CT

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Significant (but can be subtle) fractures Fracture involves the optic foramen which can cause permanent

visual loss if not treated promptly

Fracture of the posterior wall of frontal sinus requires neurosurgical evaluation and may require antibiotics prophylaxis

Fracture/dislocation of the TMJ usually missed on initial survey. It can cause significant disability if left untreated

Look for significant soft tissue injuries Globe rupture, hemorrhage

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Emergency in face injury Airway compromise due to severe soft tissue swelling, fracture

or obstructed foreign body

Life threatening hemorrhage can be from nasal injury

Facial fractures that compromise vision Orbital apex fracture may injure optic nerve, requiring urgent Rx

Entrapment of intraocular muscle requires urgent Rx

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The information provided in this presentation… Is intended to be used as educational purposes only.

Is designed to assist emergency practitioners in providing appropriate radiologic care for patients.

Is flexible and not intended, nor should they be used to establish a legal standard of care.

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Imaging Of Facial Trauma Part 3 (2) 2