Emergency Imaging. Alexander B. Baxter
Fort III fractures separate the entire midface from the cranium and involve the pterygoid plates, the orbital walls, and the zygomatic arches. The fracture passes horizontally and posteriorly through the nasofrontal suture, frontomaxillary su-ture, lateral orbital wall, zygomatic arches, and pterygoid plates. Zygomatic arch frac-ture, best visualized on axial CT images, is unique to a Le Fort III fracture, and its ab-sence excludes the diagnosis (Fig. 3.6).
◆Le Fort Fractures
The sine qua non of a Le Fort fracture is involvement of the pterygoid plates, and all Le Fort fractures e ectively separate a portion of the midface from the cranium. Le Fort I, II, and III patterns often occur in combination and can overlap with other complex fracture patterns such as mid-face smash, naso-orbito-ethmoid, and ZMC (Fig. 3.5).
The Le Fort I fracture is a horizontal max-illary fracture that traverses the pterygoid plates, inferior maxillary sinus, and nasal septum, separating the teeth and maxillary alveolus from the upper face. This injury can often be diagnosed on physical exam based on isolated mobility of the hard pal-ate. Le Fort I fractures always involve the inferior maxillary sinus walls and do not extend to the orbits or upper nasal bones.
Le Fort II is a pyramidal midface frac-ture that involves the maxillary antra and
Fig. 3.6a–fa,b Le Fort I. Transverse fracture of the maxilla with involvement of the inferior maxillary sinuses and nasal septum. The orbits and upper maxillae are intact.
c,d Le Fort II. Pyramidal fracture of the inferior orbital rims, anterior maxillary sinus walls, and nasal bridge.
e,f Le Fort III. Severely comminuted bilateral pterygoid, orbital wall, and zygomatic arch fractures. Exten-sive orbital emphysema. Severe comminution re ects overlap with midface smash pattern.
Fig. 3.5 Le Fort I, II, and III patterns.
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sinus; nasofrontal injuries involve the or-bits, orbital apices, and ethmoidal roof; andcentral smash injuries involve the orbits,maxilla, and mandible. CT shows extensivefacial bone comminution, often with pos-terior fragment displacement. Nonosseousstructures that can be injured include uppercranial nerves, globes, extraocular muscles,nasolacrimal ducts, and sinuses (Fig. 3.7).
◆Midface Smash Injury
Midface smash injury is a general term ap-plied to severely comminuted, high-energyimpact, facial fractures that are not easilycategorized as Le Fort, SMC, or NOE frac-tures. They can be loosely classified based on the their location as frontal, nasofron-tal, or central, but these categories typicallyoverlap. Frontal midface smash injuries arecharacterized by disruption of the frontal
Fig. 3.7a–fa,b Frontal type midface smash. Severely comminuted fracture, predominantly involving the frontal si-nus, but with associated comminutions of the orbital walls and maxillae.
c,d Nasofrontal type. Comminuted fractures of the nasal bones, orbital roofs, orbital oors, and frontal bone. Bilateral superior orbital extraconal hematomas. Extensive soft tissue emphysema.
e,f Central smash injury. Nasal, maxillary, and lateral orbital wall fractures.
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physema and potential medial rectus mus-cle entrapment, which can lead to diplopia on lateral gaze.
Orbital roof fractures are uncommon, and most are due to extension from fron-tal and calvarial fractures in major head injury.
CT defines the area and location of the fracture as well as any fragment displace-ment. Orbital fat herniation, extraocular muscle entrapment, and infraorbital canal involvement are easily identified. Muscle entrapment is evident clinically by diplo-pia on horizontal or vertical gaze, and cor-responding CT findings include an acute change in the angle of the muscle as it passes through the orbit or impalement of one of the muscles on a bone spicule. Intra-orbital emphysema and retroseptal intra-orbital or subperiosteal hematoma should be sought, as the former indicates risk of orbital infection and the latter may lead to increased intraorbital pressures, with secondary globe ischemia or optic nerve damage.
Surgical intervention is usually indicatedfor severe fractures to prevent late enoph-thalmos and diplopia. Emergent surgicalindications include symptomatic bradycar-dia and large orbital hematoma (Fig. 3.8).
◆Orbital Wall Fractures
Orbital wall fractures may be due to exten-sion from a calvarial or skull base fracture, or they can follow direct impact from a fist or a ball to the eye socket. In this case an abrupt increase in intraorbital pressure leads most commonly to orbital floor fail-ure with variable orbital fat herniation, in-ferior rectus or oblique muscle entrapment, orbital emphysema, and intrasinus hemor-rhage. These are often referred to as orbital blowout fractures. Clinical findings, when present, include restricted upward and lat-eral gaze, subcutaneous emphysema, and diminished sensation in the distribution of the infraorbital nerve (V2). Enophthalmos is usually not evident acutely, but it can be seen in unrepaired fractures after initial swelling resolves. Rarely symptomatic bra-dycardia can result from stretching of the infraorbital nerve (oculocardiac reflex).
Medial orbital wall, or lamina papyra-cea, fractures often occur in conjunction with floor fractures, but isolated medial wall fractures are much less common than floor fractures or combinations. Most medial orbital wall fractures are small, of little consequence, and discovered on CT obtained for other indications long after an injury. When symptomatic, medial wall fractures are associated with orbital em-
Fig. 3.8a–fa,b Orbital oor fracture. Right orbital oor fracture with depression of the lateral orbital oor. The infra-orbital canal (V2 branch) is intact. Intraorbital air and intrasinus hemorrhage.
c,d Medial orbital wall fracture. Left posterior medial orbital wall fracture with intraorbital emphysema and fat and medial rectus herniation into the posterior ethmoid air cells. The medial rectus is tethered at the anterior margin of the fracture.
e,f Orbital roof fracture. Left orbital roof fracture with extension into aerated frontal sinus. Superior orbital extraconal hematoma and orbital emphysema.
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