Search

Home Academic Radiology Academic Sections Musculoskeletal Radiology Other Teaching Materials Online MSKRadiology Book Facial and Mandibular Fractures

Facial and Mandibular FracturesFacial FracturesThe bones of the skull and face collectively make up the most complex area of skeletal real estate in the body. Analysis ofthe fractured face requires a knowledge of not only normal anatomy, but also of common fracture patterns in the face.Although they represent serious injuries, the workup and treatment of facial fractures is often properly delayed untilmore pressing problems have been addressed, such as the establishment of an adequate airway, hemodynamicstabilization, and the evaluation and treatment of other more serious injuries of the head, chest and skeleton. Once theseproblems have been managed, it is time to work up facial fractures.At our institution, high resolution CT is currently the imaging procedure of choice for most facial fractures. The complexanatomy and fractures of the facial bones are shown extremely well by CT, and soft tissue complications can be evaluatedto a far greater degree with CT. Therefore, the plain lm facial series has taken a back seat to CT in the past few years,and is now used only in certain situations, such as when the facial trauma is very focal (nasal fracture), or when CT isunavailable. However I nd it easier to initially teach the anatomy and fracture patterns of the face with plain lms. Oncethese concepts have been grasped by the resident, one can then move on to the axial and coronal anatomy shown by CT.A basic facial series consists of three or four lms: a Waters view (PA view with cephalad angulation), a Caldwell view (PAview), a lateral view, and occasionally a submentovertex view. If a nasal fracture is suspected, then a lateral view of thenasal bone with special nasal technique may be done. Of these views, the most consistently helpful view in facial traumais the Waters view. It tends to show all of the major facial structures at least as well and often better than otherradiographic views of the face.It can initially be a bit daunting to think about ruling out fractures of the complex collection of bones that make up theface. However, here are several simplifying rules that can make life a lot easier:

Look at the orbits carefully, since 60 - 70 % of all facial fractures involve the orbit in some way. The exceptions: alocal nasal bone fracture, a zygomatic arch fracture, and the LeFort I fracture. It is especially important to examinethe orbital borders and apex, as well as the optic canal.

1.

Know the most common patterns of facial fractures and look for them.2.Bilateral symmetry can be very helpful. Normal radiopacities are usually bilateral, while abnormal ones are usuallyunilateral.

3.

Carefully trace along the lines of Dolan when examining the Waters view in a facial series.4.

the lines of Dolan and the elephants of RogersWhat are the lines of Dolan? They are three anatomic contours best seen on the Waters view of the face, and they wererst popularized by Dolan et al. As you can see, the 3 lines of Dolan lead the eye along some facially important structures.Lee Rogers pointed out that the 2nd and 3rd lines together form the prole of an elephant.When you search for a fracture, you are really searching for one or more of the following radiographic signs.Radiographic signs of facial fractures

Direct Signsnonanatomic linear lucenciescortical defect or diastatic suturebone fragments overlapping causing a "double-density"asymmetry of face

Indirect Signssoft tissue swellingperiorbital or intracranial airuid in a paranasal sinus

The most common mechanism producing facial fractures is auto accidents. About 70 % of auto accidents produce sometype of facial injury, although most are limited to soft tissue. The face seems to be a favorite target in ghts or assaults,which are the next most common mechanism. The remainder of facial fractures are produced by falls, sports, industrialaccidents and gunshot wounds. Less than 10 % of all facial fractures occur in children, perhaps because of the increasedresiliency of a child's facial skeleton. The most common patterns of midfacial fractures are summarized in the tablebelow.

Fracture Type PrevalenceZygomaticomaxillary complex (tripod fracture) 40 %LeFort I 15 %

GIVE A GIFT SITE MAP CONTACT US LOGIN

Online MSK Radiology Book

General Principles

Arthritis

Appendicular Arthritis

Axial Arthritis

Lucent Lesions of Bone

Sclerotic Lesions of Bone

Periosteal Reaction

Soft Tissue Calcications

Fractures WithoutSignicant Trauma

Facial and MandibularFractures

The Painful Joint Prosthesis

Orthopedic Hardware

Scoliosis

Osteopenia

Osteonecrosis

Skeletal Dysplasias

II 10 %III 10 %

Zygomatic arch 10 %Alveolar process of maxilla 5 %Smash fractures 5 %Other 5 %

Probably the most common facial fracture is the tripod or zygomaticomaxillary complex fracture, so called because itinvolves separation of all three major attachments of the zygoma to the rest of the face.

frontal view of a zygomaticomaxillary complex fracture

submentovertex view of a zygomaticomaxillary complex fractureAlthough it may be fractured, the separation of the frontal process of the zygoma from the frontal bone usually occurs inthe form of a diastasis of the zygomaticofrontal suture. This fracture is usually due to a direct blow to the body of thezygoma. This fracture will generally cause contour abnormalities of all three of the lines of Dolan. Occasionally,extraocular muscles may become entrapped in the zygomaticomaxillary component of the fracture complex. Thedisplaced tripod fragment may physically restrict motion of the mandible. In some cases, force may propagate along thelong axis of the lateral orbital wall and involve the orbital apex or optic canal, resulting in diminished vision. CT isextremely helpful in evaluating these fractures.Fractures may be isolated to the zygomatic arch. Clinically, these injuries are usually due to a blow from the side of theface. Patients with this injury often present with atness of the lateral cheek area and inability to open their mouth, dueto impingement of the zygomatic arch fragment upon the coronoid process of the mandible or the temporalis muscle.Adequate visualization of this fracture may require a submentovertex view or CT.Another focal fracture type is a fracture of the alveolar process of the maxilla, which involves a small piece of the maxilla,associated with several fractured teeth. The main treatment goal here is to maintain viability of the teeth. If all of thefractured teeth cannot be accounted for, a chest lm should be carefully examined to look for evidence of aspirated toothfragments.Another common fracture is the orbital oor fracture, or "blowout" fracture. The usual mechanism is a blow to the eye,with the forces being transmitted by the soft tissues of the orbit downward to the thin oor of the orbit. The oor isusually the path of least resistance, and fractures downward into the maxillary sinus. Common clinical signs areenophthalmos and diplopia (especially on upward gaze), and one should remember that about 24 % of these fracturesare associated with ocular injury as well. On a Waters view, one may see a soft tissue mass on the superior margin of themaxillary sinus, representing the herniated periorbital tissues into the sinus. One may also see a "trapdoor" fragment ofbone protruding down into the sinus, often hinged on the ethmoidal side. CT will, of course, show these fractures andsoft tissue mass much better.

"blowout fracture" -- the arrows point to the fracture fragments and periorbital tissue which have herniated into themaxillary sinusThe nose is the most frequently injured facial structure, undoubtedly because of its prominent position on the face.Likewise, the most commonly missed facial fracture of the face is a fracture of the nasal bone. Although one canoccasionally see a nasal bone fracture well on a standard lateral skull lm, these fractures are much better seen when thelm is shot with special low kVp nasal bone technique (essentially soft tissue technique). One should always look at theinferior nasal spine (part of the maxilla) as well for subtle fractures. Common pitfalls in viewing the nasal bone are thenormal sutures lining the nasal bone, as well as the linear channel for the nasociliary nerve, which may all be mistaken fora fracture. A helpful rule is that this channel runs parallel to the bridge of the nose, while most nasal bone fractures willrun perpendicular to the bridge. It is well to remember that the humble nasal bone fracture may be associated with moreextensive injuries, such as the orbital rim or oor and the ethmoid or frontal sinuses.

normal nasal bone anatomyThe next set of fractures in this rogue's gallery of common facial fractures are the LeFort complexes. These are complexbilateral fractures associated with a large unstable fragment ("oating face") and invariably involve the pterygoid plates.Legend has it that LeFort dropped skulls o of a French tavern roof and analyzed the resulting fracture patterns. Thiscertainly sounds like the kind of study that we would all like to do, even without NIH funding. In reality, LeFort studiedfracture patterns produced in cadavers. He found three main planes of "weakness" in the face, which correspond towhere fractures often occur: the transmaxillary plane, the subzygomatic or pyramidal plane (this is really two planes withan apex up at the bridge of the nose), and a craniofacial plane.

frontal views of LeFort complex fractures I - III

lateral views of LeFort complex fractures I - IIIThe LeFort I, or transmaxillary fracture runs between the maxillary oor and the orbital oor. It may involve the medialand lateral walls of the maxillary sinuses and invariably involves the pterygoid processes of the sphenoid. Clinically, theoating fragment will be the lower maxilla with the maxillary teeth.The LeFort II occurs along yet another weak zone in the face, and is sometimes called a pyramidal fracture because of itsshape. A common mechanism is a downward blow to the nasal area.The most severe of the classic LeFort fracture complexes is the LeFort III. I suppose that this is pretty obvious, given athree-part grading system. In this case, the large unstable (oating) fragment is virtually the entire face! Thus, this fractureis also referred to as craniofacial disassociation. This is a very severe injury, and is often associated with signicant injuryto many of the soft tissue structures along the fracture lines. Generally, considerable force is necessary to produce thisinjury, and it is uncommon as an isolated injury. It may also occur in association with severe skull and brain injuries.With the exception of the LeFort I injury, "pure" LeFort injuries are not commonly seen. More commonly seen are variantsof the LeFort classication. One of the most common of these is the LeFort II - tripod fracture complex. This complex isusually due to the large forces encountered in a motor vehicle accident. LeFort was probably unable to apply this muchforce to the cadaver faces in his study, and it is therefore not too mysterious why he didn't describe these more complexinjuries. When describing these injuries, one should probably give a separate diagnosis to each half of the face. Evenmore complex patterns may be encountered, such as a mixed LeFort II/LeFort III complex or a LeFort III/LeFort II/tripodcomplex.Besides the classic LeFort patterns and the mixed LeFort variants, there is another common pattern which is called, forobvious reasons, a "smash" fracture. In these injuries, severe comminution of the face is present, and underlying skullinjury is likely. These patients are often in unstable condition with associated axial and appendicular skeletal injuries aswell. This category includes several varieties of otherwise unclassiable fractures, which are named for the portion of theface primarily involved. Subclassications of smash fractures include the frontal, naso-frontal (naso-ethmoid) or centralfacial smash syndromes. CT is mandatory for adequately displaying all of the bony and soft tissue components of theseinjuries.

Wise sayings about facial fracturesLook at the orbits carefully, since 60 - 70 % of all facial fractures involve the orbit in some way.1.Bilateral symmetry can be very helpful.2.Carefully trace along the lines of Dolan.3.Use CT liberally in working up facial fractures.4.

Mandibular FracturesThe mandible is another commonly fractured bone in the head, and most of these fractures are obvious on clinical exam.Clinical ndings include facial distortion, malocclusion of the teeth, or abnormal mobility of portions of the mandible orteeth.The mandible is one of those bones covered by the "ring bone rule", which may be stated thusly: if you see a fracture ordislocation in a ring bone or ring bone equivalent, look for another fracture or dislocation. You can experiment with thistendency of ring bones to break in more than one place by going through a bag of pretzels and trying to break one ofthem in just one place. Then try it with a bag of bagels. You should now have a good appreciation for Lee Rogers'corollary to the ring bone rule, which he calls the "pretzel-bagel spectrum". To wit, the stier a ring bone is, the morelikely it is to break in more than one place. The more exible it is, the more likely it is to break in just one place. Themandible has some exibility, due not only to the mobility around the temporomandibular joints (TMJ's) but also to thetendency of the TMJ's to absorb some forces during trauma. What this boils down to is that one sees an average of 1.5 to1.8 mandibular fractures per customer, depending on whether the mechanism is blue collar (st or other anonymousblunt object) or white collar (automobile crash) respectively. Like the nose, the mandible also has a prominent position onthe face, making it a favorite target for either of these mechanisms. Mandibular fractures have traditionally occurred attwice the prevalence of facial fractures, but this ratio has been decreasing with the increasing prevalence of high-speedauto accidents. Only 5 % of all mandibular fractures occur in children, and most of these are also caused by autoaccidents, with about 1/3 due to bicycle accidents.Mandibular fractures can occur at any of the following sites.

common sites of mandibular fractures

Fracture Type PrevalenceBody 30 - 40 %Angle 25 - 31 %Condyle 15 - 17 %Symphysis 7 - 15 %Ramus 3 - 9 %Alveolar 2 - 4 %Coronoid process 1 - 2 %

When double fractures occur, they are usually on contralateral sides of the symphysis. Common combinations includethe angle plus the contralateral body or condyle. Triple fractures occasionally occur, and the most common type isfracture of both condyles plus the symphysis.The mandible may also be dislocated without fracture, sometimes spontaneously during a large yawn. The patient usuallypresents with considerable pain. Spasm in the masseter and pterygoid muscles tend to force the condyles up the anteriorslope of the articular eminence and prevent normal mouth closure.

mandibular dislocation -- the condyle (c) is anterior to the articular eminence (e)Wise sayings about mandibular fractures

Remember the ring bone rule.1.Symphyseal fractures can be diabolically hard to see, even on a well-exposed AP lm2.Remember the Panorex view -- this can usually only be taken by a special machine in the oral surgery department,but it provides the best single view of the mandible and will show you fractures that cannot be seen by any othermethod short of CT.

3.

Look carefully along the cortical margin of the whole mandible for discontinuities. This may be the only sign of afracture that you will see.

4.

Also carefully examine the mandibular canal for discontinuities.5.A fracture line entering the root of a tooth is considered an open fracture by denition.6.Pathologic fractures can occur in the mandible. Look carefully for evidence of a periapical abscess or a mandibulartumor, especially if there doesn't seem to be enough trauma to match the injury.

7.

ReferencesDolan KD, Jacoby CG. Facial fractures. Semin Roentgenol 1978;13:37-51.1.Dolan KD, Jacoby CG, Smoker WR. The radiology of facial fractures. Radiographics 1984;4:575-663.2.

ABOUT USContact UsLocationsSite Map

EDUCATIONRadiology FellowshipsRadiology ResidencyNuclear Medicine Residency

SPOTLIGHTRadiology Case Reports - A Peer-Reviewed, Open Access, Online JournalRadLinks - A Medical Education App for Internet Resources in RadiologyCharles A Rohrmann, Jr. Endowed Fund for Radiology Resident Educational ExcellenceLow Radiation Dose CT

Terms and Conditions of UseOnline Privacy Statement