Radiographics%2E4%2E4%2E577

Dolan et al. Facial fractures

Volume 4, Number 4 July 1984 RadioCraphics 577

I

Introduction

Facial injury constitutes a frequent finding amongemergency room patients. Schultz and Oldham estimate that54% of such patients will have significant trauma.

The complexity of facial structures and their relativevulnerability make it important for the radiologist to havean excellent understanding of facial osseous anatomy andpatterns of injury. The injury pattern produced vanes withthe force applied and the portion of the face that receivesthe blow. Variations may also occur as a result of the size of

j the object striking the face.Facial injury evaluation plays a small role in the se-

verely injured patients overall evaluation. Survey table-topfrontal and lateral views may suffice to detect the presenceof an injury that can be more completely studied when thepatient has reached a stable condition.

We customarily use a 25 X 30 cm film in our maxillo-facial evaluation and advise against the use of small coned-down views such as those used for sinus studies. Ideally, theWaters and Caldwell views should be obtained as post-eroanterior views so that the facial bones, being close to thefilm, are optimally recorded. The posteroanterior projectionalso gives the best representation of the orbital, maxillary,and zygomatic structures because they diverge from backto front.

Kenneth D. Dolan, M.D.Professor of Radiology

Charles G. Jacoby, M.D.Associate Professor of Radiology

Wendy R. K. Smoker, M.D.Assistant Professor of Radiology

University Hospitals & Clinics,Iowa City, Iowa 52242

Complex motion (pluridirectional) tomography ispreferred for facial injury evaluation since the blurring ofoverlying structures is most complete and parasite lines areminimized with this system. We use tomography to displaydetails of injury that are obscure or, at most, are only sus-pected on plain radiographs. Tomography may also be ofvalue in studying the extent of injury in patients who, be-cause of multiple injuries, cannot cooperate for routineviews.

Computed tomography (CT) has also become signif i-cant in evaluating facial injury. Intraorbital and retrobulbarhematomas are difficult to detect by conventional means,but are easily displayed on CT. Similarly, bone detail anddisplacement may be clearly demonstrated by bone modeCT examination; i.e., CT examination with window andlevel settings adjusted to optimize bone images. Recon-struction of coronal and sagittal images by CT also may bevery important, although sometimes the seriously injuredpatient may not be able to remain motionless long enoughto allow the collection of transaxial data sufficient to permitreconstruction.

The purpose of any radiographic study of the patientwith facial injury is: 1, to provide the surgeon with infor-mation regarding the major interruptions of the facialskeleton and 2, to demonstrate any displacement of thefracture fragments that may be present. Surgical techniquesof fracture reduction and stabilization are based on suchinformation.

Similarly, neural injury may be suggested by the loca-tion of a fracture or occasionally may be directly demon-strated by CT. Cerebrospinal fluid leaks may result fromfractures of the frontal, ethmoidal or sphenoidal sinus walls.Early in the course of injury, hematoma or soft tissue her-niation may occlude the site of injury. The radiologist maysuggest the potential of such a leak, however, when thecentral sinus walls are interrupted.

Facial fractures Dolan et al.

578 RadioGraphics July 1984 Volume 4, Number 4

II

Normal Anatomy

A. SKELETAL ANATOMY

The facial skeleton arises fromand is attached to the anterior cranialfossa and the sphenoidal bones. Thebroad frontal bones have indentationsproduced by the frontal lobe gyri asseen from above in Figure 1.

The paired cribriform platesdivide the central frontal surface. Thecrista galli is located between thecribriform plates. The falx cerebriarises from the crista galli and is at-tached along a vertical ridge lyingbehind the frontal sinuses.

FIgure 1View of the anterior fossa of a driedskull preparation seen from above

1. Cerebral surface of frontal bone2. Falcine crest3. Crista galli4. Cribriform plate

5. Junction of frontal bone and lesserwing of the sphenoidal bone

6. Lesser wing of sphenoidal boneand anterior clinoid process

1. Orbits

The orbital cavities are conical in shape and havecentral axes that diverge obliquely about 35#{176}from themidline. The orbital axes project downward about 15#{176}fromthe posterior apices to the anterior rims. The orbital roofprimarily consists of the yoke-like frontal bone. Near theorbital apex, the lesser sphenoidal wings complete the roofand form the upper margin of the superior orbital fissure.

Perpendicular curved surfaces form the medial andlateral walls of the orbits. The ethmoidal sinus complex formsthe principal medial surface of the orbit. This surface isknown as the lamina papyracea. Posteriorly, this surfacemerges with the lateral wall of the sphenoid sinus. Anteri-orly, the lamina papyraeea joins the lacrimal bone. Thismerges with the frontal process of the maxilla which is at-tached to the nasal bones.

The posterior two-thirds of the lateral orbital wall isformed by the greater sphenoidal wing and its orbital pro-cess. The orbital process of the zygoma comprises the ante-nor one-third of the lateral orbital wall. Both sphenoidal andzygomatic contributions are attached to the orbital processof the frontal bone.

The orbital floor, formed by the maxillary sinus roof,is sigmoid-shaped from back to front. The anterior floor isconcave from the maxillary junction with the laminapapyracea to the maxillary process of the zygoma. Posteri-

orly, the inferior orbital fissure separates the maxillary andgreater sphenoidal wing surfaces of the orbit. The infraor-bital neurovascular structures pass through a groove in theposterior one-half of the orbital floor. Anteriorly, the in-fraorbital neurovascular structures pass through an enclosedcanal just below the orbital floor and exit through the in-fraorbital foramen.

Since the orbital floor is only a thin layer of bone, itprovides little skeletal support and depends on the thickenedmaxillary and zygomatic portions of the inferior orbital rimfor support.

2. Zygomatic Arches

The curved zygomatic arch forms a horizontal buttressextending from the body of the zygoma to the temporalprocess of the zygomatic arch. The temporal portion arisesfrom a condensation of bone just above the glenoid fossa ofthe temporomandibular joint.

3. Maxillae

The anterior, nasal and posterolateral maxillary sinuswalls form a pyramidal space whose walls, seen in transversesection, form a triangle. An anterior buttress forms the nasalfossa margin. Laterally, thickening extends from the zygoma

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Volume 4, Number 4 July 1984 RadioGraphics 579

Figure 2AA dried skull preparation in the Caldwell position for comparison withFigure 2B.

Figure 2BRadiograph of the skull In the Cald-well projection Anatomic featuresare identified in the accompanyingkey in the sequence suggested for thestudy of this view.

to the alveolar arch. Posteriorstrengthening is produced by thefused pterygoid process of the sphe-noid. The convex dental alveolarportions of the maxila are attached tothe convex hard palate which formsa horizontal supporting structure. Theperpendicular bony nasal septum isformed by the ethmoidal plate andthe vomer. This provides tenuousvertical support for the nasal bonesand hard palate.

B. RADIOGRAPHIC ANATOMY

1 . The Caidwell

(Occipitofrontal) View

The Caldwell projection shouldbe made with the central ray directedabout 250 below the canthomeatalplane to allow visualization of theorbital floor above the petrous ridge(Figure 2B).

1 . Zygomaticofrontal suture2. Orbital process of frontal bone3. Anterior orbital roof4. Upper (palpable) rim of orbit5. Frontal sinus6. Lamina papyracea7. Posterior orbital floor8. Posterior lacrimal crest9. Anterior orbital wall

10. Frontal process of maxilla1 1 . Lateral nasal wall12. Lateral maxillary wall13. Hard palate14. Perpendicular ethmoid plate and

vomer15. Superior orbital fissure16. Oblique orbital line17. Orbital process of zygoma




Figure 2CAn anterior, pluridirectional, coro-nal tomogram showing the cristagail(C) and the ethmoldalsinus roof(fovea ethmoidalls) (E) The cribri-form plate lies between these struc-tures. Inflammatory mucous mem-brane thickening partly opacifies theright maxillary sinus.

C=crista galliE=ethmoidal sinus roof-fovea

ethmoidalis3. Anterior orbital roof8. Posterior lacrimal crest9. Anterior orbital floor

1 1 . ateral nasal wall13. Hard palate14. Perpendicular ethmoid plate and

vomer

Figure 2DA dried skull preparation cut throughthe same plane as that shown in Fig-ure 2C, for comparison



Figure 2EA coronal tomogram 2 cm posteriorto the plane of Figure 2C, to illustratethe continuity of the lamina papyra-cea and the posterior orbital floor

6. Lamina papyracea7. Posterior orbital floor

1 1 . Lateral nasal wall13. Hard palate14. Perpendicular ethmoid plate and

vomer16. Oblique orbital line

Figure 2FA dried skull preparation cut throughthe same plane as is shown in Figure2E

Facialfractures Dolan et al.



2. The Waters (Occipitomental) View

The Waters projection (Figure SA) uses an occipi-tomental central ray with the patients nose and chin againstthe film holder. The maxillary sinuses are projected abovethe petrous ridges. The entire zygomatic arch is visible if theview is obtained as a posteroanterior projection.

We do not recommend tomography in this positionsince the main horizontal facial features-the maxillaryalveolus and the orbital floor and roof-are no longer per-pendicular to the tomographic plane and may not be sharplyvisible as they are in the Caldwell position.

Figure 3AA radiograph of the skull in the Waters projection Anatomic featuresvisible in this view are given in the accompanying key in the sequencesuggested for the study of this view.

1. Zygomaticofrontal suture2. Orbital process of frontal bone4. Upper (palpable) rim of orbit5. Frontal sinus6. Lamina papyracea7. Posterior floor of orbit

18. Glenoid fossa of temporomandibular joint

19. Upper margin of zygomatic arch20. Lower margin of zygomatic arch12. Lateral maxillary wall13. Hard palate21. Lower (palpable) rim of orbit22. lnfraorbital foramen23. Nasal arch




Figure 3BA dried skull preparation in the Waters position, for comparison withFigure 3A




3. The Lateral View

In the lateral view (Figure 4), structures on the two sidestend to overlap and to obscure one another. The sella turcicais well visualized and serves as a guide to the planum sphe-noidale (roof of the sphenoid sinuses). The planum and thenasal surface of the hard palate should parallel each other.An imaginary perpendicular line connecting the anteriorsurface of the frontal sinus, the anterior nasal spine and themandibular symphysis should parallel a perpendicular linealong the greater sphenoidal wing and posterior maxilla.These relationships help to define the normal positions ofthe bones on the lateral view.

The lateral position, like the Caldwell view, is a majorprojection for the tomographic evaluation of facial injury(Figures 5A-F).

Figure 4A radiograph of the skull in the lat-eralprojection Note the relationshipscited in the text.

1. Sella turcica2. Planum sphenoidale3. Nasal surface of hard palate4. Frontal sinus anterior surface5. Anterior nasal spine6. Symphysis of mandible7. Greater sphenoidal wing8. Posterior maxillary sinus wall




Figure 5AA lateral view of a dried skull preparation for comparisonwith Figure 5B.

Figure 5BA lateral tomogram through the zygomatic recess of the maxillarysinus and zygomatic and frontal processes of the lateral orbitalwall

1 . Frontal process of orbit2. Zygomaticofrontal suture3. Zygomatic process of orbit4. Anterior surface of zygomatic recess of maxilla5. Posterior wall of zygomatic recess6. Coronoid process of maxilla7. Mandibular condyle8. Greater sphenoidal wing




Figure 5CA dried skullpreparat!on cut throughthe outer one-third of the orbit toshow the lateral orbital wall The or-bital roof and sphenoidal wing areseen in section as is the zygomaticrecess of the maxillary sinus. The zy-gomaticofrontal and zygomaticos-phenoidal sutures can be followedfrom the lateral orbital border to theinferior orbital fissure.

1. Zygomaticofrontal suture2. Zygomaticosphenoidal suture3. inferior orbital fissure4. Zygomatic recess of maxillary

sinus5. Orbital roof6. Greater sphenoidal wing

Figure 5FA midline sagitta! tomogram Theposition is best defined by the sellaturcica. The frontal sinus surfaces arewell visualized. The palatal horizontalbuttress and the perpendicularvomer are also well shown in thisview.

1. Anterior frontal sinus wall2. Posterior frontal sinus wall3. Sella turcica4. Hard palate5. Vomer

Figure 5EA comparative dried skull preparation cut through thesame plane as that shown in Figure 5D




Figure 5DA sagittal tomogram through the midorbit The fused maxillaryposterior wall and pterygoid process are well seen.

1 . Orbital roof2. Lesser sphenoidal wing-anterior clinoid process3. Anterior maxillary sinus wall4. Alveolus5. Orbital floor (maxillary sinus roof)6. Posterior maxillary sinus wall7. Pterygoid process8. Pterygomaxillary fossa9. Superior orbital fissure




4. The Basal View

The submentovertex position (Figure 6A) is of valuein assessing the zygomatic arches and mandible, but may notbe obtainable in the case of severe facial injury.

Information about the frontal sinus walls, the lateralorbit, the lateral maxillary sinus wall and the greater sphe-noid wing may also be obtained. In the edentulous patient,one may also see the lateral margins of the nasal fossa.

Figure 6AA radiograph of the skull in the submentovertex projection, illustratingthe anatomic features to be identified in this basal view

1 . Zygomatic arch2. Lateral maxillary sinus wall3. Lateral orbital wall4. Greater wing of the sphenoid5. Mandibular condyle6. Horizontal mandibular ramus7. Anterior frontal sinus wall8. Posterior frontal sinus wall9. Lateral nasal fossa




Figure 6BA dried skull preparation, viewed from below, in the basal position toshow the continuity of the zygomatic arch between the temporal andmaxillary extremities. Compare with Figure 6A.

G=Glenoid fossaZ=Zygomatic arch

M=Maxilla



C. COMPUTED TOMOGRAPHIC (TRANSAXIAL) ANATOMY

The basal tomographic examination shows the samestructures as the transaxial CT views. We customarily obtainlayers 0.5 cm thick and in contiguous planes beginning atthe maxillary alveolus level and continuing through thefrontal sinus area. These views best illustrate the perpen-dicular buttresses of facial structures. The transaxial planesrecorded by CT should show horizontal structures also, butfrequently they are slightly oblique so that the hard palate,zygomatic arch and orbital floor and roof may be seen onlyin part on a given section. Anatomic structures present in thefour principal transaxial CT planes are illustrated in Figure7.

Figure 7ATransaxial CT scan located in the plane of the dentalalveolus A maxil-lary retention cyst produces opacity on the readers left.

1. Anterior nasal spine2. Anterior hard palate3. Maxillary tuberosity4. Vertical ramus of mandible5. Medial pterygoid muscle6. Masseter muscle




Figure 7BTransaxial CT scan through the midmaxillary plane Maxillary sinusdetail is most evident in this plane which is 16 mm above the plane ofFigure 7A.

1. Lateral maxillary wall2. Anterior zygomatic arch3. Anterior maxillary surface4. Section of infraorbital canal5. Bony canal for lacrimal duct6. Nasal pyramidal process of maxilla

7. Perpendicular ethmoidal plate8. Vomer9. Medial maxillary sinus wall

10. Pterygoid process1 1 . Mandibular condyle12. Tympanic surface of temporomandibular joint




Figure 7CTransaxial CTscan in the plane of the orbital floorThis plane representsthe major horizontal position of the midface. The entire zygomatic archmay be seen. The posterior maxillary sinus air cell extends upward asseen in the lateral view of the midorbit. The nasal bone and the frontalprocess of the maxilla are now evident anteriorly. The anterior andposterior lacrimal crests #{176}nclosethe lacrimal fossa along the medialorbital border.

1 . Zygomatic arch2. Nasal bone3. Frontal process of maxilla4. Anterior lacrimal crest5. Posterior lacrimal crest6. Mandibular condyle7. Tympanic bone8. Upper maxillary sinus9. Sphenoidal sinus cell in base of pterygoid pro-

cess

Figure 7DTransaxial CT scan in the plane that passes through the center of theorbit, the ethmoidal and the sphenoidal sinuses The zygomatic andsphenoid orbital processes form the lateral wall which connects pos-teriorly to the greater sphenoidal wing.




1. Glabella2. Lamina papyracea3. Ethmoidal sinus cell complex4. Zygomatic portion of lateral orbit5. Sphenoidal process of lateral orbital wall6. Greater wing of sphenoidal bone7. Sphenoidal sinus8. Superior orbital fissure



D. THE OBLIQUE ORBITAL LINE

The oblique orbital line is produced by the orbitalprocess of the sphenoid, which contributes to the lateralorbital wall. This process is well visualized on the midorbital,transaxial CT plane (Figure 7D). The oblique orbital lineis also present in the Caldwell (Figure 2B) and Waters(Figure SA) views.

Figure 8 is an anterior view of a facial skeleton prepa-ration in which drill cuts have been used to define differentparts of the lateral orbital wall.

Figure 8Anterior view ofa dried facialskeleton preparation (1) Drill cut throughthe orbital process of the zygoma posterior to the zygomaticofrontalsuture. This cut lies lateral to the oblique orbital line. (2) Cut through theorbital process of the sphenoid which interrupts the oblique orbital line.If this cut is continued further posteriorly into the greater wing proper,the lucent line extends through the oblique orbital line and both mediallyand laterally into the greater wing proper as in cut (3).

Figure 9ACa/dwell view of the skull after a right Naquin-Reece orbitotomy Theoblique orbital line is absent.




Surgical confirmation of the anatomical significanceof the oblique orbital line is found in Figures 9A and 9B.The Naquin-Reece lateral orbitotomy is a procedure bymeans of which the surgeon gains access to retrobulbarstructures through a resection of the thin sphenoidal andzygomatic processes of the lateral orbital wall. Following thisresection, the oblique orbital line disappears as seen in Figure

9A.

Figure 9BHigh Ca/dwell view of the skull after a left Kronlein orbitotomy Theoblique orbital line is absent.




The Kronlein procedure is another orbitotomy proce-dure in which the entire lateral orbital wall is removed asfar back as the greater wing of the sphenoid. This type ofresection also removes the oblique orbital line as demon-strated by Figure 9B. Since we already know the orbitalprocess of the zygoma does not produce the oblique orbitalline (Figure 8), the orbital process of the sphenoid mustproduce this line.

Some authors have attributed the oblique orbital lineto a portion of the greater sphenoid wing peripheral to theorbital process. Again, surgical evidence refutes this idea.The Caidwell view in Figure 9C demonstrates a large cra-niotomy, involving the right frontal bone and greatersphenoid wing, which was made to permit the surgeon toplace a clip on a carotid aneurysm. The sphenoidal portionof this flap extended to the edge of the orbital process as seenin the basal view illustrated in Figure 9D. Yet the obliqueorbital line is clearly defined on the Caidwell view.



Figure 9CCa/dwell view of the skullafter a right frontal sphe-noidal bone resection topermit clipping ofa carotidartery aneurysm Theoblique orbital line ispresent.

Figure 9DBasal view of the skull Thisshows resection of the lat-eral part of the greaterwing of the sphenoid onthe right.




The radiographs illustrated in Figures 1OA-D show thevalue of assessing the oblique orbital line as an index to thepresence of more extensive injury involving the posterolat-eral portion of the orbit.

Figure 1OACa/dwell view of the skull This patient has a slightly displaced left tripodfracture (not clearly shown in this projection) and interruption of thecaudal oblique orbital line. This allows one to see the transverse fractureextending into the superior orbital fissure (vertical arrows).




Figure lOBWaters view of the skull This patient has an extensive fracture of thefrontal sinus wall and upper orbital rim on the right (both poorly seenin this projection). The oblique orbital line is interrupted (arrow)suggesting extension of the frontal fracture across the orbital roof. Thiswas confirmed by tomography.




Figure lOCWaters view of the skullThis patient who has a right tripod fracture hasan interrupted oblique orbital line (horizontal arrows). Lateral to theoblique orbital line separation, one can follow the fracture (verticalarrow) which extends posterolaterally into the temporal fossa.

Figure lODCaldwell view of the skull showing avulsion of the zygoma and orbitalprocess of the sphenoid The oblique orbital line is absent. The greaterwing of the sphenoid and superior orbital fissure are intact.

Figure 11

Figure l2A



III

Radiological Signs of Facial Injury

A. SUGGESTIVE SIGNS

1 . Soft Tissue Swelling

Soft tissue swelling may decreasethe radiolucency of a facial area afterinjury. On facial radiographs, onemay detect the hematoma producedat a contact point; the soft tissueopacity should signal the possibility ofan underlying fracture. Hematomasare most easily detected in the naso-frontal, periorbital or malar areas onplain radiographs (Figure 15B, page606).

CT examination has added anew aspect to facial injury by clearlydepicting the soft tissues. Figure 11illustrates the presence of periorbitaland preseptal soft tissue swelling afterinjury. No fracture was found. Thepatient whose CT scan is depicted inFigure 12A had right proptosis anddecreased vision following injury. Inthis transaxial section the retrobulbarmuscle cone is clear.

Figure 11The value ofCTin the demonstrationof orbital hematoma This transaxialCT section represents the plane ofthe midorbit in a patient with an ex-tensive preseptal, periorbital hema-toma on the left.

Figure l2AThe value ofCTin the demonstrationoforbitaihematoma This is a similarmidorbit CT section in a patient withproptosis on the right.


602 RadioCraphics July 1984 Volume 4, Number 4

Another section, 6 mm higher,shows a large hematoma (Figure12B). An oblique lateral reconstruc-tion in the plane of the globe andoptic nerve shows the hematoma in-terposed between the orbital roof,upper muscle cone and optic canal.No fracture was found.

2. Fluid in a Paranasal Sinus

Changes in the radiolucency ofa sinus should signal possible injury.An air-fluid level or complete opaci-fication may, however, be the resid-uum of antecedent sinus disease ormay simply indicate displacement ofblood into a sinus secondary to a se-vere nosebleed.

Figures l2B & CThe value ofCTin the demonstrationof orbital hematoma (B) A more su-perior CT section in the same patientas (A) shows a large hematoma fillingthe posterior right orbit. (C) Anoblique longitudinal reconstructionshows the hematoma under the or-bital roof compressing the globe, themuscle cone and the optic nerve. G =globe; H = hematoma; 1 = orbitalroof; 2 = inferior margin of opticnerve.

A. SUGGESTIVE SIGNS

Figure 1OA Detail

Figure lOB Detail Figure 1OC Detail



B. DIRECT SIGNS

When present, the followingradiographic signs are consistent withfacial fracture. The principal differ-ence in the radiographic appearanceof each of these signs has to do withthe way in which the minor fracturefragment is displaced in relation tosurrounding bone.

1 . Separation Sign(cortical defect)

If a fracture fragment is dis-placed away from surrounding bone,a small space is produced which onradiographs produces an interruptionin bone continuity. We have demon-strated separation of the oblique or-bital line for example in FiguresbA-C. Separation may also occuralong a suture (Figure 16, page607).


604 RadioCraphics July 1984 Volume 4, Number 4

B. DIRECT SIGNS

2. Overlap Sign

If a compressive force produces a fracture, the frag-ment may be displaced so that it overlaps adjacent bone andproduces a double density along the overlapping parts.Displacement of the anterior fragment of a zygomatic archfracture in Figure 13 produces the overlap sign.

Figure 13Overlap sign This Waters view of a right zygomatic arch fracture illus-trates the overlap sign (arrow).



B. DIRECT SIGNS

3. Abnormal Linear Opacity

When a fracture fragment is rotated so that its long axisbecomes aligned with the x-ray beam, a nonanatomicallinear opacity is produced. This sign has been termed theabnormal linear density by Merrell. Displacement of alateral maxillary wall fragment produces the abnormallinear opacity in Figure 14. Duplication of the oblique or-bital line is sometimes seen and is due to the same sort ofdisplacement of the lateral orbital wall.

Figure 14Abnormalllnearopacityln this Waters view of a left tripod fracture, an abnormal linear opacity is seen (arrow). The abnormal linear opacityis produced by a displaced maxillary wall fragment. There is also dupli-cation of the left oblique orbital line as a result of displacement of aportion of the orbital process of the sphenoid.



4. Disappearing Fragment

This sign is the opposite of theabnormal linear opacity sign. Astructure that ordinarily produces acortical absorption line in a normalpatient may be rotated so that seemsto disappear after injury. In Figure15A, a 2 cm palpable inferior orbitalborder fragment has been rotated outof alignment with the beam andseemingly has disappeared. (As thereader may have assumed, the in-fraorbital nerve was injured and localnumbness resulted after this injury.)After elevation, return to normal po-sition and fixation by metal sutures toadjacent stable bone, the rim, as seenin Figure 15B, appears normal.

Figures l5A&BDisappearing fragment sign (A)

This Waters view of a patient who hassustained a local fracture of the infe-nor orbital rim (arrows) illustrates the disappearing fragment sign. (B)This figure shows restoration and wiresuture fixation of the detached frag-ment seen in (A). The arrows point topostoperative periorbital hema-toma.

B. DIRECT SIGNS

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B. DIRECT SIGNS

Figure 16Periorbital air In this Caldwell view bilateral periorbital air (A) and na-sofrontal suture separation (5) are seen.

Figure 17Displacement of a structure Comparison with the normal right sideshows the left nasal bone, the frontal process of the maxilla and the in-ferior orbital rim fragment to be displaced.

5. Periorbital or SubcutaneousAir

Penorbital air is most commonlythe result of a lamina papyracea(ethmoidal) fracture. The nasofron-toethmoidal complex injury in Figure16 produced bilateral periorbital air.We have also seen extensive facialsubcutaneous air in patients with tn-pod fractures. In such patients, airescapes from the maxillary sinuswhen the patient blows his nose.Intracranial air may also result froma fracture through the posteriorfrontal sinus wall or the ethmoidal orsphenoidal sinus roof.

6. Displaced Structure

Injury may distort the position ofa large fragment without revealingother definitive signs of a fracture onplain films. The patient whose ra-diograph is depicted by Figure 17 hasextensive displacement of the leftnasal arch, frontal process of themaxilla and much of the inferior or-bital rim. Structural displacement, incomparison with the opposite side, isthe main clue to this injury.

In other forms of injury, theremay be separation along one fracturemargin and not along others. Thisoccurs frequently in the case of tripodfractures (See Section V). Fragmentdisplacement is a frequent finding onexamination of fractures by CT.



IV

Local Facial Fracture

A portion of the orbit is involved in every form offracture except the zygomatic arch fracture, the local nasalfracture and the LeFort I injury. Thus, evaluation of theorbital borders, orbital apex or optic canal is a requisite partof the identification of most facial fractures.

Local fractures will be considered in the followingorder:

Orbital floor (blowout) fractureLower orbital rim fractureNasal arch fractureZygomatic arch fractureUpper orbital rim and frontal sinus fracture

A. ORBITAL FLOOR (BLOWOUT) FRACTURE

By definition, the orbital blowout fracture excludes aninterruption of the orbital rim. A compressive force trans-mitted by the ocular and peniorbital soft tissues to the verythin floor of the orbit is the typical mechanism of blowoutfracture. In our experience, a blow by a fist is the mostcommon cause of injury. Emery et a!. report that more thanhalf of the blowout fractures in their series were producedthis way. We have also seen this injury as a result of a blowby an elbow, a tennis ball or a handball, and it may be seenin patients who have been injured in automobile accidents.Diplopia and enophthalmos are considered the most corn-mon complications of a blowout fracture. Ocular injuriesrequiring treatment also occur and were present in 24% ofthe Emery series. Diplopia usually clears spontaneously.Enophthalrnos may be present at the time of injury if thedepressed fracture fragment is large or may develop lateras the penorbital hernatorna is absorbed.

Hammerschlags group was able to identify a blowoutfracture, using the Waters and Caidwell views, in 97% of

their cases. We agree that the majority of these fractures canbe found on plain films. The suggestive signs listed above(soft tissue swelling and sinus opacification or air-fluid level)are often present with a blowout fracture. Definite dis-placement of bone spicules or a larger fragment should bethe principal diagnostic criterion. The ethmoidal surface isinvolved in this fracture pattern in about 40% of cases.

Thin-section tomography plays an important part inblowout fracture evaluation. If surgery is considered, to-mograrns provide the best cross sectional study of the orbitalfloor and lamina papyracea. CT may provide evidence oforbital floor disruption in transaxial or coronal sections, butis a costly diagnostic medium. We reserve CT for the studyof complicated cases that cannot be resolved by more con-ventional study.

An undisplaced blowout fracture is illustrated by Figure18A. Only a small soft tissue mass below the orbital floor isvisualized on the Caldwell view in Figure 18B.

Figures 18A & BUndisplaced right blowout fracture (A) This Waters view clearly dem-onstrates the fracture line (arrow). (B) A Caldwell view shows only anoval mass in the right maxillary sinus (arrow).




Most often, the displaced blowout fracture fragmentwill appear as an abnormal opacity resembling a trapdoorthat is hinged toward the ethmoidal side of the orbit. Thistype of injury is demonstrated by Figure 19. Peniorbital fatproduces the soft tissue shadow protruding through the floor.In this case (Figure 19), upward gaze was limited and theforced-duction test was positive. If the blowout fragmentreaches the posterior orbital floor, the cortical line will seemto disappear (disappearing fragment sign) on the Caldwellview, as seen in Figure 20A. Usually the displaced floor willproduce an abnormal linear opacity in the Waters view asdemonstrated in Figure 20B.

Figure 19Mid floor blowout fracture on the leftThe arrow points to the fragmentthat simulates a trapdoor.

Dolan et al. Facialfractures


Figures 20A & BPosterior blowout fracture on the left (A) The posterior floor cortex isabsent on the left at the arrow in this CaIdwell view. (B) In the Watersview, an abnormal linear opacity (arrow) represents the displaced orbitalfloor fragment.




CT was helpful in delineatingthe very large defect produced by aleft blowout fracture in the patientwhose studies are shown in Figure 21.The Caldwell view, Figure 21A,demonstrates a large lamina papyra-cea and orbital floor defect. Deepenophthalmos is suggested by thebroad, air filled upper tarsal skin foldindicated by the arrows. Enophthal-mos is confirmed by the midorbital,transaxial CT section shown in Figure21B. This also shows a long ethmoidalsurface indentation. The orbital floorand lower ethmoidal defects areconfirmed in a lower transaxial CTscan (Figure 21C). The defects,especially the one in the orbital floor,are best seen in Figure 2bD, a directcoronal CT scan.

Figures 21A & BLarge left orbital floor and laminapapyracea defect (A) A Caldwell viewshows absence of the cortices of thelamina papyracea and orbital floor.The left maxillary sinus is opacifiedand there is prominence of the tarsalfold (arrows). (B) In this midorbitaltransaxial CT scan, enophthalmos ispresent together with an ethmoidalsurface defect.

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Volume 4, Number 4 July 1984 RadioGraphics

Figures2lC&DLarge left orbital floor and lamina papyracea defect(C) The ethmoidaland orbital floor defects are seen in this low orbital, transaxial CT scan.(D) A direct coronal CT scan shows the large defect.

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B. LOWER ORBITAL RIM FRACTURE



The use of tomography in eval-uating a blowout fracture of the or-bital floor and lamina papyracea isillustrated in Figure 22. The increasein the volume of the orbit producedby this fracture (Figure 22) easilyexplains the persistent en-ophthalmos that was noted clinicallyin this patient.

Figure 22Blowout fracture Marked medialdisplacement of the lamina papyra-cea and downward displacement ofthe right orbital floor are seen in thistomogram of a blowout fracture.


Figures 15A & BInferior orbital rim fracture (A) This detail shows disappearance ofan inferior orbital rim fragment because of its rotation. (B) This detailshows reappearance of the fragment as a result of its surgical resto-ration to normal position.



B. LOWER ORBITAL RIM FRACTURE

A blow directed to the lower or-bital rim may produce a rim frag-ment such as that illustrated in Fig-ures 15A and 15B. In this case, thedirection of force caused rotation ofthe detached fragment so that itseemed to disappear. A more lateralsegment of the inferior rim has beenseparated in the injury illustrated byFigure 23A. The detached fragmenthas been displaced downward andmedially.

In many inferior orbital rimfractures, a portion of the anteriororbital floor will be included in thefragment. Often the floor will be ob-scured by the rim fragment. In Fig-ure 23B, the left rim fracture (upperarrows) and displaced orbital floor(lower arrows) are both evident. Lessapparent is the lamina papyraceafracture indicated by thickeningalong this surface of the orbit.

Figures 23A & BInferior orbital rim fracture (A)There is downward and medial dis-placement of an outer orbital rimfragment (arrows). (B) An orbital rimfracture is seen at the upper arrows.A fragment of the orbital floor (dis-placed inferiorly) is seen at the lowerarrows.



C. NASAL ARCH FRACTURE

Nasal tip fractures are commonplace. Isolated fracturesare best visualized on an underexposed lateral view. Thisview also can be used to define more severe injury to thebony margins of the nasal fossa. Interruption of the anteriornasal spine and premaxilla may also be defined by the lateralview.

The patient whose radiograph is illustrated in Figure24A, has extensive injury of the maxillary margins of thenose, anterior nasal spine, and premaxilla. Fragment sepa-ration in all of these fractures occurs in the sagittal plane andis, therefore, best seen in the lateral view. While fracture ofthe nasal arch might be suspected from the changes in Fig-ure 24A, no direct evidence of such an injury is present onthe lateral view.

Since the nasal arch is oriented in a coronal plane, it isbest seen in the Waters view. Figure 24B is from the sameexamination as Figure 24A. In this Waters view, both nasalbones are seen to have been separated from the perpendic-ular plate of the ethmoid and from both maxillary frontalprocesses. The left maxillary frontal process has been in-terrupted along the medial border of the maxillary sinusproducing opacification of the sinus. A portion of the pre-maxilla injury can be seen between the central incisors. Thefacial surgeon is concerned about the airway and cosmeticappearance of the patient with a nasal injury. Therefore,information such as that recorded in Figures 24A and B canbe very helpful to the surgeon.

Figures 24A & BExtensive nasal injury (A) This lateral view shows a nasal tip fractureat the upper arrow, a fracture of the frontal process of the maxilla at themiddle arrows and an anterior nasal spine fracture at the lower arrows.(B) This Waters view shows a nasal arch fracture at A, frontal processfracture at B, and a portion of the premaxilla fracture at C.




Nasal arch interruption may alsosignal more extensive injury of theorbital rim, orbital floor, ethmoidalsinus and frontal sinus. The left nasalbone and maxillary frontal process areseparated from the remainder of thenasal arch in Figure 25A. The frontalprocess is separated also along themedial maxillary sinus border and atthe medial edge of a displaced orbitalrim fragment. The nasal bone andfrontal process form a large fragmentwhich has the shape of an invertedY at the arrows. The entire orbitalfloor has been displaced downward.An accompanying Caidwell view,Figure 25B, shows the associated leftlamina papyracea fracture and fur-ther demonstrates the extent of theorbital floor fracture.

Figures 25A & BLeft nasalarch fracture with frontalprocess, orbital rim and floor in-voivement (A) This figure shows aninverted Y produced by fracturesof the left nasal bone and the frontalprocess of the maxilla (upper 3 ar-rows). The orbital rim is detached andforms a disappearing fragment.There is an orbital floor fracture at thelower vertical arrow. (B) A laminapapyracea fracture is seen at the ar-rows.



A force applied to the left fron-tal, nasal and orbital areas producedthe injury depicted by Figure 26. Astellate frontal sinus fracture extendsalong, and interrupts, the upper,inner border of the left orbital marginin Figure 26A. The nasal arch iscomminuted and displaced down-ward. The perpendicular plate of theethmoid and the vomer are separatedin the center of the nasal septum.Rotation of the fragments repre-senting the maxillary frontal processand the inferior orbital rim has re-suIted in a step-like deformity of theinferior rim, and the orbital floor isinterrupted. In the Caldwell view,Figure 26B, the left maxillary frontalprocess displacement can be seen, anda blood clot opacifies the frontal sinus.Figure 26C is a lateral view thatshows fractures of the upper andlower margins of the frontal sinus, aswell as ethmoidal roof fractures.These changes should suggest that thepatient may develop a cerebrospinalfluid leak.

Figures 24-26 illustrate the pointthat extensive central axis and orbitalinjury may accompany an interrup-tion of the nasal arch.





Figures 26A, B & CStellate frontal sinus fracture There is, in addition, depression of thenasal arch, fracture of the nasal septum, displacement of the frontalprocess of the maxilla and fracture of the orbital floor. (A) This Watersview shows a stellate frontal fracture and upper orbital rim fracture(open arrow). Rotation of the frontal process of the maxilla producesa step-off with the lower rim (curved arrow). A septum fracture is in-dicated by the horizontal arrows. (B) In this CaIdwell view comparisonwith the normal right side (arrows) confirms the displacement of theleft frontal process of the maxilla. The frontal sinus is opacified. (C) Thelateral view shows frontal fracture margins (arrows) and ethmoidal roofseparation (arrowheads).

Faclalfractures Dolan et al.


The zygomatic arch is vulnera-ble to a blow from the side of the facewhich produces fractures with inward(medial) displacement of the frag-ments centrally and outward (lateral)displacement of the fragments at thezygomatic and temporal ends of thearch. This fracture complex is easilydetected in the Waters projection, asis seen in Figure 13. Occasionally, theanterior element of a zygomatic archfracture may involve the body andthe orbital process of the zygoma. TheWaters view in Figure 27A demon-strates the central indentation of thezygomatic arch and the outwarddisplacement of the temporal portionof the arch that is typical of an archfracture. Anteriorly, the other frac-ture with outward displacement hasoccurred through the orbital processand body of the zygoma. The latterfracture is more evident in Figure27B, the Caldwell view. Rarely, azygomatic arch fracture will be ac-companied by a transverse fracturethrough the body of the zygoma asseen in Figure 28.

Figures 27A & BZygomatic arch fracture with ante-nor component through the bodyand orbitalprocess ofthe zygoma(A)This Waters view shows inbendingat A, temporal process outbendingat B, perpendicular outbendingthrough the zygoma at C. (B) A Cald-well view of the same patient showsextension of the fracture along theouter portion of the orbital process(arrows).

D. ZYGOMATIC ARCH FRACTURE



D. ZYGOMATIC ARCH FRACTURE

Figure 13Zygomatic arch fracture This detailshows the characteristic appearanceof a zygomatic arch fracture as seenin the Waters view.

Figure 28Zygomatic arch fracture withtransverse extension of the anteriorfracture through the body of the zy-goma Note the medial displacement(inbending) of the arch centrally atA, the lateral displacement of thetemporal process (outbending) atB, and the transverse fracture of thezygoma at C.



The upper orbital rim is infre-quently fractured but may becomevulnerable if the frontal sinus is largeas in the case of the patient whoseradiograph is illustrated in Figure 29.Figure 29 shows two large upper or-bital rim fragments that have beendisplaced downward. Tomogramsdemonstrated involvement of onlythe anterior upper orbital rim andouter frontal sinus wall. Followingreduction, the outer (lateral) frag-ment was wired to the stable orbitalprocess of the frontal bone. Themedial fragment was then anchoredto the stabilized lateral fragment byanother wire suture. Comminutionprevented further suturing of themedial fragment, but as is seen inFigure 29A, the upper inner orbitalrim was held in good position by softtissues.

Figures 29A & BUpper orbital rim fractures in a pa-tient with a large frontal sinus (A)The fractures (arrows) produce twolarge fragments that are displaceddownward. (B) Following reductionand fixation, the upper orbital borderhas been replaced in anatomic posi-tion.

E. UPPER ORBITAL RIM FRACTUREAND FRONTAL SINUS FRACTURE




Figure 30Comminuted fracture Involving the right upper orbital rim, the frontalsinus and ethmoid sinus A longitudinal orbital roof fracture (upperarrow) extends posteriorly through the lesser wing of the sphenoid. Ablowout fracture is present at the lower arrow.

The application of more exten-sive force results in orbital roof, eth-moidal and orbital floor (blowout)fractures such as those seen in Figure30. In this patient, the entire rightupper orbital rim and adjacent frontalsinus wall are comminuted. Thelamina papyracea is also fractured,and a long segment fracture of theorbital roof as well as a blowout frac-ture of the orbital floor are present. Insuch a case, one would expect de-tachment of the trochlear sling for thesuperior oblique muscle, and a cere-brospinal fluid leak might possiblydevelop. The patients vision was in-tact.

Facial fractures Dolan et al


CT may be very helpful in thestudy of fractures involving thefrontal sinus, but CT does not dem-onstrate the upper orbital rim well. Afracture of the anterior surface of thefrontal sinus is well defined in Figure3bA. Lower CT sections failed toshow comminuted fragments alongthe upper, inner orbital rim, whereas,these were quite evident on plain ra-diographs. One might also be misledinto thinking a large fracture frag-ment was present by the appearanceof the normal superior orbital neu-rovascular grooves seen in FigureSiB.

Figures 31A & BComminuted, depressed fractureinvolving the anterior wall of the leftfrontal sinus and the inner, upperorbital rim (A) This CT sectionthrough the frontal sinus shows thedepressed left anterior frontal sinuswall and opacification of the frontalsinus on the left. (B) This CT section,at a lower level, shows the fracture atthe central arrow. The outer arrowsindicate normal suborbital neuro-vascular grooves.




V

The Tripod Fracture

A. USUAL MANIFESTATIONS OF THE TRIPOD FRACTURE

A number of regional terms have been applied to theform of fracture that involves the attachments of the zygo-ma. It has been referred to interchangeably as the zygo-maticomaxillary fracture complex, the zygomaticofacialfracture, the trimalar fracture and the tripod fracture.

The term tripod fracture is used throughout thisdiscussion because it best reflects the three-legged stoolarrangement of the zygoma and its principal attachments.Posteriorly, the narrow temporal process of the zygoma helpsto form the zygomatic arch. Superiorly, the orbital processof the zygoma unites with the orbital process of the frontalbone at the zygomaticofrontal suture. The orbital processalso has a thin posterior lamella that unites with the orbitalprocess of the sphenoid to form the lateral orbital wall. In-feriorly, the broadest and most supportive part of the zy-goma is found in the maxillary process which covers thesuperolateral margin of the maxillary sinus and which, in thewell developed sinus, is pneumatized by the zygomatic re-

cess of the sinus. The orbital portion of the zygomatico-maxillary suture reaches nearly as far as the infraorbitalforamen. The tripod fracture results in separation of thezygoma from these three major bone attachments; hence,the tripod fracture implies an interruption of all threelegs.

An example of a left tripod fracture is illustrated inFigure 32. Force, which was directed in a medial and pos-tenor direction, was applied over the body of the zygoma.An air-fluid level is present in the maxillary sinus, and anoblique fracture line spans the outer maxilla. The movableouter portion of the inferior orbital border is elevated. Themobile lateral portion of the maxilla is displaced medially.A line of separation is present in the zygomatic arch. All ofthese features are evident in the Waters view, Figure 32A.The Caidwell view, Figure 32B, best shows the zygomati-cofrontal suture separation. The lateral orbital wall fractureis not evident in this projection, however.

Figures 32A & BLeft tripod fracture (A) This Waters view shows orbital rim interruptionat A, a lateral maxillary fracture at B, and an undisplaced zygomatic archfracture at C. (B) The Caldwell view shows a zygomaticofrontal sutureseparation at the arrow.

Figure 33A




The right tripod fracture frag-ment in Figure SSA has been dis-placed downward so that the mobile,outer fragment of the inferior orbitalrim lies below the level of the stablemedial aspect of the rim. The lateralmaxillary portion of the detachedtripod fragment has been displacedmedially producing a double line justabove the alveolus. Downward dis-placement of the movable anteriorportion of the zygomatic arch has alsooccurred. Zygomaticofrontal sutureseparation is more obvious on theCaldwell view in Figure SSB.

After reduction, the restoredorbital rim and zygomaticofrontalfixation points produced by wire su-tures are illustrated in Figures SSCand D. Improvement in the positionof the zygomatic arch and of the lat-eral maxillary wall fragment is alsoseen in these views.

Figure 33B



Figure 33C

Figure 33D


Figures 33A-DDownward displacement ofa right tripod fracture(A) This Waters viewshows the outer rim fragment at A to be in a lower than normal position.There is duplication of the lateral maxillary border at B, and downwarddisplacement of the zygoma fragment at C. (B) The arrow marks sepa-ration of the zygomaticofrontal suture. Orbital rim and zygomati-cofrontal fixation wires are seen in the postreduction Waters (C) andCaldwell (D) views.



B. SUPPLEMENTARY VIEWS FOR TRIPOD FRACTURES

We have seen how valuable theWaters and Caldwell views are inevaluating the tripod fracture. Theright tripod fracture illustrated by aWaters view in Figure 34A is barelyvisible because of its minimal dis-placement. A Towne projection of thesame patient (Figure 34B) permitsevaluation of the anterior, postero-lateral and medial maxillary sinuswalls. On the patients left, the sinusmargins are intact; on the right, ex-tensive comminution of the anteriorand posterolateral maxillary surfaces,as well as, posterior displacement ofthe zygoma are present. The zygo-matic arch is usually too overexposedto view on a Towne projection, butmay be seen in this projection on anunderexposed radiograph.

Figures 34A & BThe Towne projection in tripodfracture evaluation (A) In the Watersview, a barely discernible right tripodfracture is seen. (B) The Towne pro-jection shows the anterior, A, pos-terolateral, B, and medial, C, maxil-lary margins on the left to be intact.The anterior and posterolateralmargins on the right are comminuted(arrows).

1Dolan et al. Facial fractures


B. SUPPLEMENTARY VIEWS FOR TRIPOD FRACTURES

The underexposed basal view ispreferred for the evaluation of thezygomatic arch position and providesinformation about the position of thebody of the zygoma, as well. A lefttripod fracture is seen in the Watersview in Figure 35A. In this projection,a zygomatic arch interruption mightbe suspected from the angulation ofthe arch, but separation is not seen.Figure 35B, an underexposed basalview, clearly shows outward (lateral)bending of the zygomatic arch; it alsodemonstrates posterior displacementof the body of the zygoma. Thesefindings are better seen in a detail ofFigure 35B (Figure 35C).

Pluridirectional tomography andCT are reserved for the evaluation ofcomplications of the tripod fracturethat will be considered in a subse-quent section.

Figures 35A, B & CLeft tripod fracture (A) A Waters view clearly shows thefracture. A line of separation between fragments (arrows)parallels the left oblique orbital line. (B) and detail (C) An

underexposed basal view shows outbending of the zygo-matic arch (horizontal arrow) and posterior displacementof the body of the zygoma (vertical arrow) when comparedwith the opposite side.

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RadioGraphics July 1984 Volume 4, Number 4

C. MANDIBULAR FUNCTION AND THE TRIPOD FRACTURE

When the zygomatic arch por-tion of a tripod fracture extends intothe glenoid fossa of the temporo-mandibular joint, pain on motion ofthe mandible may cause the patientto restrict motion. Such an injurysimulates a mandibular condyle in-jury. The joint capsule may also beinjured. Occasionally the tripodfragment will be so displaced thatmandibular motion is physically re-stricted. The zygoma fragment inFigure 36A is displaced downward tosuch an extent that it rests against thecoronoid process of the mandible.This prevented the patient fromclosing her mouth. The Caldwell viewof this patient (Figure 36B) bettershows the extent of the downwarddisplacement of the tripod fragment.This patient also had fractures of thenasal arch, of the frontal process ofthe maxilla and of the left maxillaryalveolus. The alveolar injury pro-duced the oblique position of theupper teeth seen in these views.

Figures 36A & BTripod injuryand displacement pre-venting closure of mouth (A) TheWaters view shows the zygoma, Z, toencroach on the coronoid process ofthe mandible, C. The nasal arch andthe frontal process of the maxilla arealso fractured. (B) This Caldwell viewshows marked zygomatic displace-ment.

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Figure 37

Figure 38



C. MANDIBULAR FUNCTION AND THE TRIPOD FRACTURE

Inability to close the mouthimplies injury while the mouth wasopen; inability to open the mouthimplies injury while the mouth wasclosed. The patient whose radiographis seen in Figure 37, for example, wasstruck when his mouth was closed.The zygoma impinged on the coro-noid process, and the patient couldnot open his mouth. The patientwhose radiograph is illustrated byFigure 38 had a shearing fracture ofthe tip of the coronoid process sec-ondary to the displacement of a tn-pod fracture.

Figure 37Tripod injuryand displacement pre-venting opening of the mouth In thisWaters view, the right zygoma, Z, isseen to be displaced against the co-ronoid process of the mandible, C.This prevents opening of themouth.

Figure 38Right tripod fracture with fracture ofthe coronoid tip (arrow)



D. VARIATIONS IN LATERAL ORBITAL INVOLVEMENT IN TRIPOD FRACTURES

A mandibular ramus fracturemay be produced during the samesort of altercation that results in atripod fracture. Such an injury isdemonstrated in Figure 39. In theWaters view (Figure 39A), a left tn-pod fracture is seen; the posteroan-tenor view (Figure 39B) shows theaccompanying intercondylar man-dibular fracture.

Figures 39A & BLeft tripod andassociated mandibu-lar fractures (A) This Waters viewshows a left tripod fracture (arrows).(B) A posteroanterior view shows anintercondylar fracture (arrow).



D. VARIATIONS IN LATERAL ORBITAL INVOLVEMENT

IN TRIPOD FRACTURES

Whereas the majority of tripodfractures involve the zygomati-cofrontal suture, variations occur andrequire adjustments in surgical re-pair.

For example, in Figure 40A, thezygomaticofrontal suture is intact, butthe orbital process of the zygoma isinterrupted. Orbital process fixationwas achieved with a suture spanningthe fracture (Figure 40B).

Figures 40A & BTripod fracture with low-lying orbitalprocess fracture (A) This preopera-tive Waters view shows an irregularfracture line through the orbital pro-cess of the right zygoma rather thanseparation of the zygomaticofrontalsuture. (B) This radiograph was madeafter surgical reduction and fixationof the fractures.

Faclalfractures Dolan et al.


D. VARIATIONS IN LATERAL ORBITAL INVOLVEMENTIN TRIPOD FRACTURES

In another variation, the orbitalprocess of the frontal bone may besheared off in association with a tn-pod fracture. When this occurs, thereis usually an accompanying separa-tion of the zygomaticofrontal suture,as well. This is seen in Figure 4iA inwhich there is medial displacement ofboth the zygomatic and frontal con-tnibutions to the lateral orbital wall.The surgeon, again, must adjust thesuture fixation points to produce sta-bility. This principle is illustrated inFigure 41B.

Figures 4lA & BTripod fracture with high orbitalprocess fracture (A) This preopera-tive view shows a fracture throughthe base of the orbital process of thefrontal bone (arrows). (B) The resultobtained by reduction and fixation ofthe minor fragments is seen in thispostoperative Waters view.




Medial displacement of the or-bital processes (or of the frontal bone)is usually accompanied by extensiveorbital floor injury. This is seen inFigure 42 in which the transverseorbital dimension is markedly nan-rowed by the displaced frontal pro-cess of the zygoma. The comminutedorbital floor is displaced into themaxillary sinus. Clinically, no ocularmuscle entrapment was present, butlateral gaze was restricted.

Figures 42A & BMedial displacement of the lateralorbital border with orbital floor in-terruption (A) A Waters view showsdisplacement of the orbital floorproducing an abnormal linear opacity(arrow). (B) Comminution of the or-bital floor (arrow) is shown in thisCaldwell view.




If the greater sphenoid wingportion of the lateral orbital bonder isinjured, the oblique orbital line willbe interrupted, and an overlap signwill appear where fragments are su-penimposed as in Figure 43A. Thespatial relationships of such fragmentsare best defined on transaxial CT asillustrated in Figure 43B.

Figures 43A & BRight tripod fracture with Involve-ment of the orbital process of thegreater wing of the sphenold(A) TheCaIdwell view shows interruption ofthe oblique orbital line (verticalarrow) and an overlap sign (horizontalarrows). (B) This transorbital CT scanshows the overlapping (arrows) of thefragments in the transverse plane.

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E. ORBITAL APEX AND OPTIC CANAL INJURYCOMPLICATING THE TRIPOD FRACTURE

If the force producing a tripodfracture is applied in the direction ofthe long axis of the lateral orbital wall,injury to the orbital apex and sun-rounding structures may occur. Plu-nidinectional tomography and CT areuseful for demonstrating suspectedorbital apex injury. The patient whoseradiograph is illustrated in Figure 44had a right tripod fracture accom-panied by diminished vision in theright eye. Careful evaluation of theCaldwell view revealed an abnormallinear opacity along the lateral bonderof the superior orbital fissure (Figure44A). A section from a coronal to-mognaphic study confirmed thepresence of a fracture in the greaterwing of the sphenoid and demon-strated a lessen sphenoidal wingfracture with clockwise rotatory dis-placement (Figure 44B). Opacity ofthe ethmoidal sinus was also presenton the night.

Figures 44A & BRight tripod fracture with orbitalapexlnjury(A) A Caldwell view showsan abnormal linear opacity (arrow).(B) This coronal tomogram of thesuperior fissure area shows clockwiserotation of a lesser sphenoidal wingfragment with fractures (arrows).

637




In Figure 45, the radiographs of another patient witha night tripod fracture and orbital apex injury are shown.Figure 45A is a coronal plunidirectional tomogram illus-trating a lessen sphenoid wing fracture with clockwiserotation similar to that in Figure 44B. The lateral tomograms(Figures 45B and C) show the lessen wing and anterior cli-noid process to have been separated from the planumsphenoidale and tubenculum sellae.

Figures 45A, B & CRight tripod fracture with orbitalapex injury(A) This coronal polyto-mogram shows rotation of a lesser sphenoidal wing fragment withfractures (arrows). (B) A lateral polytomogram through the plane of thesella again shows separation of the lesser wing of the sphenoid (arrows).(C) A lateral parasellar polytomogram shows lesser wing and anteriorclinoid separation (arrows).




639




A CT study of a similar injury is illustrated by Figure46. Figure 46A is a tnansmaxillany section showing inter-ruption of the left anterior and postenolatenal maxillary sinusborders. Figure 46B is a transaxial section through the mid-orbit that shows angulated fragments of the orbital processof the greater sphenoidal wing displaced into the orbitalapex. Ethmoidal and sphenoidal sinus opacity implies medialorbital wall injury. A coronal CT reconstruction shows howthe border of the superior fissure formed by the greaten wingof the sphenoid has been displaced upward above the levelof the lesser wing (Figure 46C).

Thus, the tripod fracture may vary from a relativelyminor flattening of the malan eminence, to a fracture thatis associated with injury that can imperil vision. On occasion,a patient may have tripod fractures bilaterally. This is il-lustrated by Figure 47A. The examiner must make sure thatthe central nasofrontal axis is not injured in order to differ-entiate the bilateral tripod injury from the more extensiveLeFort II injury. The Caidwell view (Figure 47B) showszygomaticofrontal suture separation on the left; whereas,on the night, there is a transverse fracture of the orbitalprocess below the suture. The result achieved by reductionand fixation of the fragments is shown in Figure 47C.

Figures 46A, B & CLeft tripod fracture with orbital apex injury(A) A transmaxillary CT scandemonstrates anterior and posterolateral maxillary fractures (arrows).(B) A transorbital CT scan shows displaced fragments (arrows) of theorbital process of the greater wing of the sphenoid encroaching on theapex of the orbit. The fragment at A would produce an abnormal linearopacity on plain films. (C) In this coronal reconstruction of CT data, eI-evation of the greater wing of the sphenoid is seen at the arrow.



Figures 47A, B & CBilateral tripod fractures (A) ThisWaters view shows the transmaxillary(arrows) and arch fractures (arrow-heads). (B) The zygomaticofrontalsuture is separated on the left, but afracture of the transverse orbitalprocess (arrows) is present on theright in the CaIdwell view. (C) ThisWaters projection was made aftersurgical reduction and fixation of thefragments.

Figure 48A



VI

Complex Fractures

Complex facial injuries are either bilateral on implysevere comminution of several parts of the facial bonecomplex. This category of injury is here divided into twogroups: the LeFort and the smash types of fracture.

LeFORT INJURIES

Rene LeFort was a French surgeon who studied severefacial injury extensively and identified three basic forms offacial injury in the laboratory. (His articles have beentranslated into English by Tilson, McFee and Soudah.) Fromhis experimental work, LeFort described three planes ofweakness in the facial bones. Subjected to certain types

of traumatic force, the facial bones tend to fracture alongone on more of these planes. Separation at the fracture siteresults in the formation of a large, complex detached frag-ment that is unstable. Because of its instability, the positionof such a detached fragment may become altered relativeto its site of origin. Treatment is directed at stabilizing theupper jaw in a functional position. LeFonts planes ofweakness are outlined in Figure 48. He originally describedthe craniofacial separation as the first plane of weakness andthe transmaxillary plane as the last. For some reason, un-known to us, customary contemporary usage describes thetransmaxillary fracture as the LeFort I and the craniofacialseparation as the LeFort III fracture. To avoid confusion,we will use the contemporary usage.

Figure 48B



LeFORT INJURIES

Figures 48A & BThe LeFort planes of weakness (A) This anteroposterior view corre-sponds to a CaIdwell projection. (B) Lateral view.



A. THE LeFORT I FRACTURE

The LeFont I plane of weakness traverses both medialand lateral walls of the maxillary sinuses. Posteriorly, thepterygoid processes of the sphenoid are interrupted. Thisresults in a floating palate fragment. Often, the maxillarydental arch will be in the anterior open bite position. Thisimplies that the maxillary molars are approximated to themandibular molar teeth, whereas the maxillary and man-dibulan incisors are separated.

It is suggested that one begin evaluation of a LeFontinjury with inspection of the lateral view. This allows eval-uation of the ptenygoid processes and posterior maxillarywalk In Figure 49A, the ptenygoid processes are interrupted.Similarly, the walls of one zygomatic recess have beenfractured. An anterior maxillary fracture separation is also

Figure 49A

present, and there is a slight anterior open bite. The trans-maxillary fracture is best seen in the Waters view, Figure49B. This also shows the anterior open bite and extension ofthe fracture through the inferior portion of the left zygo-matic recess.

Restoration of dental structure position was accom-plished with interdental wines. Further stabilization wasproduced by suspension wines placed through drill holes inthe bodies of the zygomas as seen in Figure 49C. The sus-pension wires were attached to the interdental wines below.This brings the movable maxillary fragment into optimalposition with respect to the stable portion of the maxilla asshown in Figure 49C.

Figure 49B

Figure 49C



A. THE LeFORT I FRACTURE

Figures 49A, B & CLeFort I fracture (A) This lateral viewshows pterygoid process fractures atA, zygomatic recess fractures at B,and an anterior maxillary surfacefracture at C. (B) In a Waters viewtransmaxillary fractures are seen(arrows). (C) This Waters view wasobtained after surgical reduction andsuspension of the fragments.



B. THE LeFORT II FRACTURE

The LeFont II fracture illustrated by Figure 50A hasinterrupted the pterygomaxillary contices. Slight posteriordisplacement of the palatal fragment is present. The marginsof the zygomatic recesses of both maxillary sinuses have beeninterrupted and comminution in the nasal-ethmoidal areais present. A slight anterior open bite position of the dentalstructures is evident.

Downward displacement of the pyramidal fragmentis illustrated by the Waters view in Figure 50B. The nasalarch and underlying glabella are fractured. Both inferiororbital borders are interrupted. A step-off is present on thenight, whereas, less displacement is present on the left. Bothlateral maxillary sinus walls are fractured at the inferiorzygomatic margin and at the junction between the lateralmaxillary wall and the dental alveolus. Both lateral orbitalwalls and zygomatic arches are intact. The right frontalprocess of the maxilla is comminuted and notated off the axis

Figure 50A

so that it is not seen in this view (disappearing fragmentsign). The left frontal process is in good position, but is sep-arated from the medial maxillary sinus wall. The left orbitalfloor has been fractured and is displaced downward into theupper maxillary sinus. All of these features reflect that theforce application was oven the nasal arch, a little to the rightof the midline, and was directed obliquely downward andposteriorly in order to produce the resulting position of themain fragment.

After reduction and fixation of the orbital rim andnasofrontal fractures, the application of an arch ban andinterdental wining, the resulting fragment position is almostanatomic as seen in Figure 50G. Slight caudal displacementof the left orbital floor remains. The surgeon chose to loopthe suspension wire over the zygomatic arch on the night,while the left suspension wire was placed through thearch.

Figure 50B

Figure 50C



B. THE LeFORT II FRACTURE

Figures 50A, B & CLeFort II fracture (A) A lateral viewshows pterygoid process fractures atA, zygomatic recess fractures at Band a nasal-ethmoidal fracture at C.Note the posterior position of thehard palate and slight anterior openbite. (B) This Waters view shows thepyramidal fragment produced by themultiple fractures (arrows). (C) ThisWaters view shows the result ob-tained with surgical reduction andfixation of the fragments.

Figure 51B



C. THE LeFORT III FRACTURE

The true LeFort III fracture is very uncommon as anisolated injury. Fracture through this plane more commonlyoccurs as a unilateral part of the LeFort Il-tripod injurywhich will be described below. The LeFort III fracture mayoccur in association with severe skull injury, however.

The patient whose injury is demonstrated in Figure 51had a severe head injury which produced a temporopanietalfracture extending across the middle cranial fossa and sella.The blow also has resulted in a left mandibular ramusfracture for which interdental wining had already beenperformed before the nadiographs were obtained. The lateralview in Figure 51A (and detail in Figure 51B) shows thetemporoparietal and tnanssellan components of the injury.Though partial reduction has occurred, the pterygomaxillaryinterruption is still evident (arrow).

Figure 51A

Because of brain injury, only a table-top, antenoposte-rion Waters projection could be obtained. This view, FigureSiC, demonstrates a shift of the facial structures to thereaders left. An interrupted nasal arch is present and bothzygomatic arches are fractured just in front of the glenoidfossae. The inferior orbital rims and lateral maxillary sinuswalls are intact. A table-top antenopostenion view in theCaldwell position is illustrated by Figure 51D. In this, a langeleft upper orbital rim fragment is present and is notatedslightly clockwise. The nasal-ethmoidal fracture is evidentcentrally. On the right, a zygomaticofrontal suture sepana-tion is present along with a perpendicular separation of thelateral orbital wall. Shift of the upper facial fragment to thereaders left is again evident. Thus, the entire facial super-structure has been detached from its cranial attachments andhas been displaced in position.

Figure 51C



Figure 51D


Figures5lA,B,C&DLeFort Ill fracture (A & detail B) Thelateral view shows an extensive tem-poroparietal (small arrow) andtranssphenoid fracture (arrowhead).There is a pterygoid process fractureindicated by the large arrow. (C) Atabletop anteroposterior Waters viewdemonstrates interruption of thenasal arch and fractures of the zygo-matic arches (arrows). (D) A table-topanteroposterior Caldwell view showsan upper orbital rim fragment at A,and a nasal-ethmoidal fracture at B,as well as suture separation and alateral orbital wall fracture at C.




Tomography is advised for the study of the details ofLeFort injury patterns. Figure 52A is a tomognam that showsa longitudinal hand palate fracture and right frontal fracturecomplicating a LeFont II injury pattern. Comminution ofthe left inferior orbital rim and lateral maxillary wall are alsopresent. If the presence on location of the pterygoid processfracture is not evident on plain films, tomography may behelpful. The patient whose radiograph is illustrated in Figure52B had bilateral ptenygoid process fractures associated witha LeFont II injury. The injury shown in Figure 52C wasthought to represent a LeFont II injury on plain films. Thetomognaphic study demonstrates that the fracture patternis actually a LeFort I with a large fragment involving the leftfrontal process of the maxilla. The night nasal and orbitalbonders are intact on the tomognaphic study. Tomographymay also help to define orbital apex and optic canal injuriesas we have seen in earlier examinations.

Figure 52A

Figure 52B

Figure 52C




Figures 52A, B & CTomographyas an adjunct means ofevaluating LeFort injuries (A) Thisanteroposterior tomogram shows ahard palate fracture at A, and a rightfrontal fracture at B complicating aLeFort II injury. (B) This tomogramshows pterygoid process fractures(arrows) that were not evident onplain views. (C) This patient sustaineda LeFort I fracture, but a large leftfrontal process fragment (arrows)resembled a LeFort II fracture onplain films.



D. LeFORT FRACTURE VARIATIONS

1 . The LeFort 11-Tripod Fracture Complex

We have illustrated in Figure 52C that large fragmentLeFort injuries need not be symmetrical. This asymmetryis the principal variation in LeFont injury forms and mayassume any night sided and left sided variation. Thesevariations result from variations in the size and shape, di-nection and velocity of the injuring surface that comes intocontact with the face. Perhaps, one of the most frequentvariations is the fracture in which a LeFort II fragment anda tripod fragment are produced by the same injury. Thisform of fracture must be produced only by a very greatforce, inasmuch as severe comminution is present at pointsof impact. These fractures usually result from motor vehicleaccidents and must result from the application of greaterforce than LeFont was able to apply in his studies, for he didnot describe this combination of injuries among his inducedfractures.

The Waters view in Figure 53A shows marked com-minution in the left nasal-ethmoidal area and along the leftlateral maxillary sinus bonder. On the right, the inferiororbital rim and lateral maxillary sinus wall are separated in

Figure 53A

the LeFont II plane. This produces the central pyramidalfragment. In addition, there is a left tripod fragment thatresults from separation of the zygomaticofnontal suture andlateral orbital wall; the zygomatic arch is fractured near theglenoid fossa. The tripod fragment is displaced toward thepatients left side while the LeFont fragment is displaced tothe night. Thus, in the LeFort Il-tripod designation, theradiologist must call the attention of the surgeon to the twoprincipal fragments that require stabilization.

A second aspect of this fracture is the severe frontal onethmoidal roof injury that frequently accompanies theLeFont Il-tripod injury. In the lateral view, Figure 53B(and detail 53C), the posterior maxillary and ptenygoidprocess fractures are seen as are fractures of the zygomaticrecess margins. Air-fluid levels are present in the high para-sagittal region of the panietal area. This finding impliesdural laceration with air escaping from a sinus cavity. If onecarefully evaluates the lateral view, one finds no evidenceof the ethmoidal roof. This reflects severe injury to thecentral portion of the anterior cranial fossa. A Caidwell viewof this patient gives supplementary information regardingthe nasal arch comminution, shows the left lateral orbitalwall fracture and confirms the intracranial location of theair.

Figure 53B Figure 53C

Figure 53D



Figures 53A, B, C & DA LeFort Il-tripod fracture (A) ThisWaters view shows comminution ofthe nasal arch and left maxillary bor-der. There are fractures in the LeFortII plane on the right at the verticalarrows. A left tripod fracture is mdi-cated by the horizontal arrows. (B)The upper arrows are on intracranialair-fluid levels; the lower arrows mdi-cate an ethmoidal roof (fovea) defect.(C) This detail of B demonstratespterygoid process fractures (arrows)and zygomatic recess fractures (ar-rowheads). (D) A Caldwell viewsshows nasal arch comminution, a leftlateral orbital wall fracture and intra-cranial air (arrows).

Figure 54A



D. LeFORT FRACTURE VARIATIONS

2. The LeFort lI-LeFort III Fracture Complex

If the point of impact in a complex injury is above thenasal arch area, the propagation of force may be along theLeFort III plane as seen in Figure 54. The force, in this case,was applied oven the left frontal, left zygomatic and leftmandibular area (Figure 54A). A right-sided fracture in theLeFort III plane of weakness is also seen. An Erich arch banwith interdental wining spans an oblique horizontal namusmandibular fracture, which is not visible on this view. Thiscomplex of fractures has produced a large facial fragmentand would be designated as a LeFont Ill-right, a LeFortIl-left, plus a left tripod fragment as well. The proximalportion of the left zygomatic arch has also been sheared offthrough the glenoid fossa. The right inferior orbital rim isintact in both the Waters view and the Caldwell view illus-

tnated by Figure 54B. The large tnansfnontal fracture is alsobetter seen in this view, as is the bilateral zygomaticofrontalsuture separation. A view of this patient after reduction andfixation is shown in Figure 54C. Wire sutures maintain theleft orbital rim fracture. Zygomaticofrontal suture fixationhas been achieved and incorporated with suspension wines,which are attached to surface buttons for easier removalafter the suspension wines are no longer needed. An externalT-shaped splint protects the frontal fracture. While thisfracture is clearly along the LeFort III plane of weakness onboth sides, it would be insufficient to designate the fractureas such, for this would fail to call attention to the inferiororbital rim and lateral maxillary wall fractures on the left.Hence, the use of the more comprehensive term LeFontIl-tripod for the injury on the left.

Figure 54B

Figure 54C

Dolan et at. Facial fractures


Figures 54A, B & CComplex fracture consisting ofa ieftLeFort 11-tripod and right LeFort illinterruption (A) This Waters viewshows a large fragment resulting froma right LeFort Ill fracture (verticalarrows) and a left LeFort II fracture(oblique arrows). A left tripod frag-ment is also present (O-). An Ericharch bar spans the mandibular teeth.(B) The Caldwell view defines thetransfrontal (arrows) and zygomati-cofrontal suture separation (shortarrows) better. (C) This Waters viewwas obtained after surgical reductionand fixation.

Figure 55A

Facial fractures Dolan et at.


E. SMASH FRACTURE

This categorical term is used to imply injury from theapplication of great force producing rather complete com-minution of all the facial structures. The term is usuallymodified to describe the pontion of the face primarily in-volved. We use the following terms: nasal-ethmoidal smash;frontal smash; or central facial smash to describe the threemajor forms of this injury.

The use of the term smash also implies that associatedinjury of the underlying pants of the skull is likely. Thus, inthe case of the nasal smash injury, one would expect ocular,orbital apex and ethmoidal roof injury. Similarly, the frontalsmash injury implies an interruption of the frontal sinus wallsand strongly suggests underlying dunal and brain injury. Inthese forms and in the central facial smash, the middlecranial fossa is injured, along with the sphenoidal sinus walls.Rarely, the accompanying basal skull fracture will extendinto the temporal bone and produce facial, auditory or

vestibulan nerve injury.Patients with a smash injury usually have not only ac-

companying skull trauma, but axial on peripheral skeletalinjury as well. Because of the patients unstable generalcondition or skeletal injury, it is usually not possible to obtainmore than a table-top facial bone x-ray examination. To-mography may be a very helpful supplemental examinationand CT becomes very useful for facial analysis and brainevaluation.

Figure 55A is the Waters view of a patient with anasal-ethmoidal smash injury. In this, the nasal pyramidbonders are hardly recognizable and fractures through eachof the vertical and horizontal facial buttresses are present.The Caldwell view of this patient in Figure 55B further il-lustrates the nasal-ethmoidal comminution and reveals asmall left frontal sinus air-fluid level. Bilateral zygomati-cofrontal suture separation is present.

Figure 55B

Dolan et at. Facialfractures


E. SMASH FRACTURE

Figure 55A & BNasal-ethmoidal smash injury(A) The multiple fractures of this complexinjury are seen here in the Waters view. (B) This is a Caldwell view of thesame patient. See text for description of the findings.

Facialfractures Dolan et at.


E. SMASH FRACTURE

A frontal smash injury is shown in Figure 56. Thefrontal sinus walls were comminuted and had been de-compressed by the time a lateral view, Figure 56A, couldbe obtained. Ethmoidal roof interruption and an opaquesphenoidal sinus are also evident in this view. Figure 56B isa table-top antenoposterion view of the same patient. All of

Figure 56A

the facial buttresses have been interrupted. Figure 56C isa postenoantenion view after reduction and fixation of thefragments. Obvious distortion of the frontal sinus, nasal archand left orbit persists. Patients who sustain such devastatinginjury often require extensive cosmetic surgical repair.

Figure 56B

Figure 56C

Dolan et at. Facial fractures


Figures 56A, B & CFrontalsmash injury(A) This lateralview was obtained after surgical fixa-tion of a fracture involving the ante-nor wall of the frontal sinus. It showsmultiple fractures some of which areindicated with arrows. (B) The multi-ple fractures are here demonstratedin a table-top anteroposterior Watersview. (C) The extent of the injury isbetter demonstrated in this postop-erative Waters view.

Facial fractures Dotan et at.


E. SMASH FRACTURE

Only emergency survey antenopostenion and lateralviews w

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