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322 PART V ORAL AND MAXILLOFACIAL SURGERY
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2% sodium fluoride solution is applied for 20 minutes. Evaluation for endodontic therapy is done at
7 to 10 days following replantation. In avulsed teeth with a closed apex and a dry time greater than
60 minutes, endodontic therapy can be performed prior to replantation and the necrotic periodontal
membrane should be gently cleaned prior to implantation. A soft diet and a week of chlorhexidine is
advised in addition to close follow-up.
18. What is the treatment for root fractures?
The tooth is repositioned and stabilized with a splint for at least 4 weeks. Root fractures closer to the
cervical region may require longer splint times (up to 4 months).
19. What are the options available for crown-root fractures in the secondary
dentition?
• If there is no pulpal involvement, the coronal fragment may be removed.
• With pulpal involvement, the coronal segment is removed, and endodontic therapy is performed.
This is then followed by orthodontic versus surgical extrusion or ostectomy with gingivectomy.
• With vertical crown-root fractures, the tooth should be extracted. Extraction should not be delayed,
whereas the other modalities may be delayed for 1 to 2 weeks after bonding of the coronal
fragment.
20. What is the treatment for alveolar fractures?
The alveolar bone is repositioned using manual digital pressure followed by splint therapy for at least
4 weeks. Associated lacerations must be identified and treated.
21. Which injury has highest incidence of pulpal necrosis?
Intrusion has more pulpal necrosis (65% to 90%), whereas extrusion causes 64% of pulpal necrosis.
22. How are intruded primary teeth managed?
Intruded deciduous teeth are extracted, as displacement of the root apex may damage the develop-
ing secondary tooth. If the root apex of the deciduous is displaced labially, it may be left in place and
observed for spontaneous eruption.
23. How are root fractures of deciduous teeth managed?
Treatment depends on whether the coronal fragment is displaced. If there is no displacement then no
treatment is indicated. With displacement the coronal fragment is either splinted or extracted leaving
the apical portion in place.
BiBliography
Abubaker AO, Giglio JA, Murino AP: Diagnosis and management of dentoalveoilar injuries. In Fonseca RJ, editor: Oral and
maxillofacial surgery, Philadelphia, 2000, W.B. Saunders, pp 54–85.
Andreasen FM, Andreasen JO: Diagnosis of luxation injuries: the importance of standardized clinical, radiographic and
photographic techniques in clinical investigations, Endod Dent Traumatol 5:160–169, 1985.
Andreasen FM, Andreasen JO, Tsukiboshi M: Examination and diagnosis of dental injuries. In Andreasen JO, Andreasen
FM, Andersson L, editors: Textbook and color atlas of traumatic injuries to the teeth, ed 4, Oxford, 2007, Blackwell,
pp 255–279.
Bakland LK, Andreasen JO: Examination of the dentally traumatized patient, Calif Dent Ass J 24:35–44, 1996.
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Hani F. Braidy, Vincent B. Ziccardi, A. Omar Abubaker
1. What are the signs and symptoms that may be associated with mandibular
fractures?
Signs and symptoms associated with mandibular fractures include pain and tenderness at the fracture
site; changes in occlusion; ecchymosis of the floor of the mouth or skin; crepitation on manual palpation; soft tissue bleeding; sensory disturbances (numbness of the lower lip); changes or deviation of
the mandible on opening; soft tissue swelling; trismus; flexion or segmental mobility of the mandible;
gingival tears and palpable fracture line intraorally or at the inferior border of the mandible.
2. What is a compound mandible fracture?
A compound mandible fracture is a fracture in which there is an external wound involving the skin,
mucosa, or periodontal ligament structure (contaminated wound). A compound fracture is at increased
risk for infection.
3. What radiographs are included in a mandible series?
The mandible film series includes the right and left lateral oblique views, posteroanterior (PA) cepha-
logram, and reverse Towne’s view. The lateral oblique views are useful to evaluate the body or ramus
regions of the mandible. The PA view can assess the symphyseal region and evaluate the buccallingual displacement of body or angle fractures. The reverse Towne’s view is helpful in assessing the
mandibular condyles. Panoramic radiographs remain the gold standard for mandible fracture screening. Because these are seldom available in hospital radiology departments, an additional view that is
oriented perpendicular to the lateral cortex can be substituted to accurately assess and diagnose a
fracture. A panoramic radiograph combined with a PA or reverse Towne’s view is generally adequate
for diagnosis. Maxillofacial computed tomograms without contrast are becoming widely available and
can be an invaluable adjunct to plain films.
4. Which mandibular fractures are likely to be missed on panoramic examination?
Because panoramic radiograph is a flat view taken by a movable X-ray beam that displays the
entire mandible as a flat structure, some overlap and blurring are usually seen in the symphysisparasymphysis region; therefore, fractures of the mandible in this area are frequently missed.
Similarly, and due to the overlap from other cranial and facial structures, fractures of the mandibular
condyles can be difficult to detect, and when one is detected, it can be difficult to ascertain the
degree of displacement of the fracture. The combination of panoramic examination, Towne’s views,
and computed tomography (CT) scans helps detect almost all mandibular fractures.
5. What is the incidence of fractures in different areas of the adult mandible?
See Table 30-1.
6. What is a horizontally favorable fracture?
Favorability is determined by the forces exerted by the masticatory muscles on the fracture seg-
ments. A favorable fracture is one that is not displaced by masticatory muscle pull, and an unfavorable fracture occurs when the line of fracture permits the fragments to separate. The four muscles
of mastication are the temporalis, masseter, medial pterygoid, and lateral pterygoid. After discontinuity of the mandible due to fracture, these muscles exert their actions on the fragments, leading to
malocclusion. Horizontal favorability is determined by cephalad-caudad stability as seen on CT or
oblique films. An example of a horizontally favorable fracture is a body fracture where the inferior
border is displaced superiorly by the pterygomasseteric sling stabilizing the reduction because of
fracture orientation.
7. What is a vertically favorable fracture?
Vertical favorability is evaluated in the buccal-lingual plane. A vertically favorable fracture of the angle
occurs when oblique fracture lines form a large buccal cortical fragment that prevents medial displacement.
Unfavorable vertical mandibular angle fracture as seen on axial CT reveals that a vertically unfavorable
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Table 30-1. Fracture Incidences in Different Areas of the Adult Mandible
AREA OF MANDIBLE PERCENT OF FRACTURE INCIDENTS
Angle 31%
Condyle 18%
Angle (molar) region 15%
Parasymphysis 14%
Symphysis 8%
Cuspid 7%
Ramus 6%
Coronoid process 1%
fracture line extends from a posterolateral point to an anteromedial point. No obstruction counters the action
of the lateral pterygoid and mylohyoid muscles, and the posterior fragment is shifted medially.
8. How does muscle pull affect displacement of mandibular fractures?
Muscles involved in displacing mandibular fractures include the medial and lateral pterygoid, tempo-
ralis, masseter, digastric, geniohyoid, genioglossus, and mylohyoid. The lateral pterygoid displaces the
condyle anteriorly and medially because of its insertion on the pterygoid fovea. Muscles attached to
the ramus (i.e., temporalis, masseter, and medial pterygoid) result in superior and medial displacement of the proximal segment. As fractures progress anteriorly toward the cuspid region, the digastric,
geniohyoid, genioglossus, and mylohyoid exert a posterior-inferior force on the distal segment.
9. How do pediatric mandibular fractures differ from adult mandibular fractures?
In general, mandibular fractures are less common in children than in adults. When mandibular
fractures occur in children, greenstick fractures of the mandible, particularly in the condylar region,
are relatively common. Also, the ossification capability of children allows faster healing and distinguishes them from adult mandible fractures. As a result, many mandibular fractures in children can
be treated with immobilization for a shorter period or observation and soft diet compared to adults.
Open reduction and internal fixation in children are reserved for severely displaced fractures. Resorbable plates and screws are often used instead of metallic ones when open reduction and internal
fixation are indicated. Problems with osteosynthesis in children include the need to avoid damage
to developing tooth buds and the need to remove the plates at a later time if resorbable plates are
not used. Another common feature of mandibular fractures in children is the occurrence of high and
intracapsular condylar fractures.
10. What are some of the common complications associated with mandibular fracture
management?
• Infection
• Delayedunionornonunion,usuallyresultingfrominfectionorinadequatefixation
• Malocclusion
• Facialortrigeminalnerveinjury
• Damagetotoothroots
• Hematoma
• Wounddehiscence(mostcommoncomplication)
• Toothinjury
• Osteomyelitis
Of these, infection is one of the most problematic and is an important cause of nonunion.
11. What are the risk factors that predispose mandibular fractures to infection?
Fractures that occur through the tooth-bearing area should be regarded as contaminated. Infected
mandibular fractures are often seen in patients who sustain facial trauma and fail to seek immediate treatment. Mucosal tears and fractures extending through the periodontal ligament produce
contamination of the fracture by oral flora. Bony sequestra, devitalized teeth, hematoma, and poor oral
hygiene also contribute to infection.
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The most common cause of postoperative infection, however, is movement at the fracture site
due to loose, mobile hardware, such as a loose screw in an otherwise stable plate. This may cause
infection and drainage intraorally or extraorally or both until the source of infection is removed.
Patients with polysubstance abuse and malnutrition are especially at risk for wound healing complications and osteomyelitis.
12. What percentage of mandibular fractures are multiple?
More than 50% of mandibular fractures are multiple. Accordingly, detection of one fracture in the mandible
should alert the examiner to the possible presence of additional fractures due to the arch form of the
mandible. Radiographic examination should then be directed toward identification of additional fractures.
13. What percentage of patients with mandibular fractures are associated with
concomitant cervical spine injury?
Approximately 43% of all patients with mandibular fractures have associated other systemic injuries.
Cervical spine fractures were found in 11% of this group of patients. It is imperative to rule out cervical neck fractures, especially in patients who are intoxicated or unconscious and in patients who are
involved in vehicular accidents. Posteroanterior, lateral films, and CT of the neck should be reviewed
with the radiologist before treatment is initiated in these patients.
14. What potential fatal outcome can result from bilateral mandibular parasymphyseal
fractures?
Bilateral parasymphyseal fractures may result in a free-floating anterior mandibular segment. The
genial tubercles to which the genioglossus muscle is attached are located on the lingual surface of
the mandible. Lack of stability in this area in the presence of a displaced unstable bilateral symphyseal fracture allows for posterior displacement of the tongue, which can result in airway embarrassment and inferior displacement by the suprahyoid musculature. This is known clinically as “gag
bite” and can lead to death. In these types of fractures, serious consideration should be given to
securing the patient airway in the early phase of management of these patients. Urgent treatment
may be to place interdental wire stabilization or suture through the tongue to allow extension.
15. What factors contribute to condylar displacement in patients with a condylar
fracture?
The lateral pterygoid is the only muscle that inserts directly on the neck of the mandibular condyle.
In subcondylar fractures, the forces of this muscle frequently result in anterior and medial displacement of the condyle. The patient will deviate to the side of the fracture upon opening because of the
unopposed action of the contralateral lateral pterygoid muscle. In higher condylar fractures and with
intracapsular fractures above the insertion of the lateral pterygoid fractures, the small fragment can
occasionally be seen displaced in a pure horizontal or vertical direction.
16. What surgical techniques are available to treat mandible fractures?
The most frequently used treatment modalities available for the management of mandible fractures are:
• Closedreductionandmaxillomandibularfixation(MMF)withIvyloops,archbars,ortransalveolarscrews
• Closedreductionandfixationwithgunningsplintssecuredtostableosseousstructures(circum-
mandibular or perialveolar wires)
• Externalpinfixation,usedprincipallywithcomminutedandgrosslycontaminatedfractures
• Openreductionwithinternalfixationusingintraoralincisions,extraoralincisions,orendoscopy.
With this technique, the segments may be secured across the fracture site with wires, plates, or lag
screws with or without concomitant MMF.
17. What effects do MMF have on the masticatory system?
• Osteoporosisofbonefromdisuseatrophy
• Weaknessofthemusclesofmasticationanddecreasedrangeofmotion
• Capsularandpericapsularfibrosis
• Cartilagethinning
These listed changes are usually reversible once MMF has been discontinued.
18. What are the indications for external fixation of mandible fractures?
Indications for external fixation of mandible fractures include:
• Extensivefracturecomminutionwithsofttissueloss(i.e.,severegunshotwounds).Inthesesitu-
ations, external fixation may help preserve the vitality of small bony segments and allow the soft
tissue to heal prior to definitive treatment.
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• Infectedfractureswhenextensivecellulitisand/orosteomyelitis,incombinationwithabscess
drainage and bony debridement. The use of external fixation circumvents extensive extraoral
incisions, challenging neck dissections, and placement of internal hardware in grossly infected
sites.
• Proximalsegmentcontrolandspacemaintenanceafterseveretraumaorresection
19. What are uniphasic and biphasic external fixation systems?
A uniphasic system, such as a modified Roger Anderson device, involves two or more percutaneous
pins on either side of the fracture connected by a bar. External pin fixation systems are also commercially available using pin fixation, connectors, and carbon rods.
A biphasic system, such as a Joe Hall Morris device, entails the use of a temporary reduction
appliance until a secondary device (usually cold cure acrylic) is placed to connect the pins.
20. What are the advantages of rigid internal fixation (RIF) in treatment of mandible
fractures over other techniques? What are the disadvantages of RIF?
RIF of mandibular fractures allows early mobilization of the jaws, reducing or eliminating the period of
MMF. This is a significant benefit to patients, avoiding the potential sequelae of prolonged immobilization, including temporomandibular joint (TMJ) stiffness after removal of MMF, social inconvenience,
phonetic disturbance, loss of effective work time, discomfort, and weight loss. In contrast, open
reduction of mandibular fractures with wire osteosynthesis (nonrigid) requires 4 to 8 weeks of MMF
for satisfactory healing. Closed reduction with MMF requires the patient to be in MMF for 6 weeks or
more, with limitation of diet and function, and difficulty in maintaining good oral hygiene. Disadvantages of RIF include surgery incision with possible scars and nerve injury, anesthesia complications,
and higher cost of procedure.
21. What are the different options for treatment of mandibular angle fractures?
The treatment of these fractures depends on many factors, including but not limited to the age and
medical condition of the patient, severity of the fracture, and displacement. In general, for most angle
fractures, superior border plate fixation with a minimum of four screws placed across the fracture
line provides adequate stability of the fracture. The patient can be placed in MMF for 1 to 3 weeks,
although that is not always necessary. Plates used range from 1.0 to 2.0 mm with monocortical
screws that range in length (depending on the thickness of the cortical plate and the positioning of
the plate) from 5 to 7 mm. Other treatment options include an inferior border plate or lag screw across
the fracture line. If the fracture is nondisplaced, MMF for 3 to 6 weeks represents a viable option for
treatment. With comminuted fractures of the angle, treatment options include external pin fixation,
reconstructionplate,and/orMMF.
22. What are the indications for removing a tooth in the line of fracture?
Because mandibular fractures commonly occur through the dental periodontal ligament space, much
debate has been focused on whether to extract teeth in the line of fracture. By definition, a fracture
that communicates with the oral cavity through the periodontal ligament space is considered a
compound fracture. The literature to date does not provide convincing evidence that infection is more
likely to occur if a tooth is retained. Nonetheless, current recommendations for removal of teeth in the
line of fracture include:
• Presenceofobviouspathology,suchascariesorperiodontaldisease
• Grossmobilityofinvolvedteeth
• Teeththatpreventadequatereductionoffractures
• Teethwithfracturedroots
• Teethwhoserootsurfacesorapicesareexposedinthefracturesite
23. What are the indications for open reduction and internal fixation of condylar fractures in adults?
Most fractures of the mandibular condyle are amenable to closed reduction with fixation and immobi-
lization ranging from 7 to 21 days based on age of the patient, displacement of fracture, and number
of other concomitant injuries. Intracapsular condylar fractures are generally treated with a short period
of MMF (10 to 14 days), followed by physiotherapy to prevent ankylosis of the joint. The mandible will
deviate clinically to the side of injury on opening because of unopposed pull of the contralateral lateral
pterygoid muscle.
The indications for open reduction of condylar fractures in adults were well described by Zide
and Kent and divided into absolute and relative indications.
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Absolute Indications:
• Inabilitytoobtainadequateocclusionusingclosedreductiontechniques
• Displacementofthecondyleintothemiddlecranialfossa
• Severeangulationsofthecondyle,lateralextracapsulardisplacementofthecondyleorthecondyle
outside the glenoid fossa
• Removalofforeignbodyinthejointcapsule(e.g.,gunshotpellets)
Relative Indications:
• Bilateralcondylarfractureswithconcomitantcomminutedmidfacialfractures
• Bilateralfracturesinanedentulouspatientwhensplintsareunavailableorimpossiblebecauseof
severe ridge atrophy
• Displacedcondylefractureinamedicallycompromisedpatient(e.g.,seizuredisorder,psychiatric
problems, or alcoholism) with evidence of open bite or retrusion
24. What are the risks factors for developing TMJ ankylosis following trauma?
• Intracapsularfractureofthemandibularcondyle
• Pediatricpopulation
• Prolongedimmobilization(ormaxillomandibularfixation)ofthefracture
• Intraarticularhemorrhagewithsubsequentfibrosisofthejoint
25. When treating mandible fractures, what is a tension band?
During mandibular functioning, stress forces are exerted on the bone in different vectors depending
on the location. The superior border is under tension, whereas the inferior border is compressed. A
rotational force is found in the parasymphyseal region. A tension band in mandibular fracture management refers to a mechanical means of resisting fracture displacement in the tension zone. This may
be accomplished by a superior border plate if teeth are not in the way (i.e., a plate over the external
oblique ridge in an angle fracture), an arch bar if stable teeth are present on both sides of the fracture,
a superior border wire, or an eccentric dynamic compression plate at the inferior border. Essentially,
the tension plate stabilizes the destabilizing forces of the mandible.
26. What are dynamic compression, eccentric dynamic compression, and passive
plating in rigid fixation?
The concept of rigid internal fixation was designed to allow primary bone healing even under func-
tional loading. In an effort to enhance stability, plates were developed that provide compressive forces
across fracture lines. Passive plating provides rigid fixation without compression. Dynamic compression plates compress the fracture site by providing axial guiding inclines for the screw heads to slide
down as the screw is tightened. The screws first engage the bone, and as they are tightened, they are
moved 0.8 mm toward the fracture site by the guiding incline. This produces a compressive force of
approximately 300 kPa. Eccentric dynamic compression plates provide compressive forces in more
than one direction by changing the direction of the guiding incline in the outer holes of the plate. This
concept is useful when plating mandibular body fractures. A compression plate at both the superior
and inferior borders would ideally provide compression throughout the fracture, but is usually not possible because of the presence of teeth superiorly, as well as other vital structures. A single eccentric
dynamic compression plate placed at the inferior border serves the same purpose by angling the
guiding inclines of the outer holes toward the superior border of the mandible and eliminating the
need for a superior border tension plate.
27. How are atrophic mandibular fractures treated?
There is considerable controversy over the choice of treatment methods of these fractures. However,
many authors agree that the most important element to the success of the treatment of these fractures
is adequate and complete stabilization of the fractured segments. Lack of complete immobilization of the
fractured segments is likely to account for most of the commonly reported nonunion of these fractures,
especially when nonrigid or semirigid fixation is used (such as wires, miniplates, and denture splints).
Nonrigid or semirigid plates will not provide adequate and effective stabilization, and will likely fail with
function. There is always the concern for devascularization of the bone from open reduction and reflection of the periosteum of the mandible; open reduction and rigid fixation using a reconstruction plate or
a titanium mesh with immediate bone graft provide much more predictable results of healing of these
types of fractures. Because atrophic mandible fractures are usually observed in the elderly and unhealthy
population (often with respiratory and nutritional problems), early and adequate stabilization and resumption of oral intake provide a better chance of primary bony healing of fractures in these patients.
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BiBliography
Aargon SB, Gardner KE: The mandibular fractures. In Jafeck BW, Murrow BW, editors: ENT secrets, ed 2, Philadelphia,
2001, Hanley & Belfus.
Aminoff MJ, Greenberg DA, Simon RP: Clinical neurology, ed 3, Stamford, Connecticut, 1995, Appleton & Lange.
Assael LA: Maxillofacial trauma. Part 1: applying science to practice, Oral Maxillofac Surg Clin North Am 10(4), 1998.
Braidy HF, Ziccardi VB: External fixation for mandible fractures. Atlas of the Oral and Maxillofacial Surgery Clinics
17(1):45–53, 2009.
Deangelis AJ, Backland LK: Traumatic dental injuries: current treatment concepts, J Am Dent Assoc 129:1401–1414, 1998.
Ellis III E: Treatment methods for fractures of the mandibular angle, J Craniomaxillofac Trauma 2:28–36, 1996.
Fonseca RJ: Oral and maxillofacial trauma, ed 4, St Louis, 2012, Saunders.
Polley JW, Flagg JF, Cohen M: Fractures of the mandible. In Weinzweig J, editor: Plastic surgery secrets, ed 2, Philadelphia,
1999, Hanley & Belfus.
Posnick, JC: Craniomaxillofacial fractures in children. Oral Maxillofac Clin North Am. 1994;1:169.
Smith BR, Ghali GE: Atrophic edentulous mandibular fractures, Oral and maxillofacial surgery knowledge update, vol 2.
1998.Tra/29Chicago,PublisherisAAOMS.
MANAGEMENT OF
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ZYGOMATICOMAXILLARY
COMPLEX AND ORBITAL
FRACTURES
Siavash Siv Eftekhari, Tuan Bui, Michael J. Grau Jr., Deepak G. Krishnan
ZYGOMATICOMAXILLARY COMPLEX
AND ORBITAL FRACTURES*
1. What is the anatomy of the zygomaticomaxillary complex?
The zygomaticomaxillary complex (ZMC) is part of the midface bony structure contributing to facial
width, cheek prominence, and inferior and lateral borders of the orbit. The zygoma has four projections,
which create a quadrangular structure, connected to four bones, which include: maxillary bone at the
zygomaticomaxillary (ZM) buttress, frontal bone at the zygomaticofrontal (ZF) suture, temporal bone
at the zygomaticotemporal (ZT) suture, and sphenoid bone at the zygomaticosphenoid (ZS) suture.
The zygomatic arch includes the temporal process of the zygoma and the zygomatic process of the
temporal bone. The sensory nerve to the zygoma is the second division of the trigeminal nerve. The
zygomatic arch may be fractured independently or as part of this complex. ZM and ZF are part of the
vertical buttresses of the midface and correct alignment of these structures is imperative in reestablishing facial projection, facial width, and orbital volume.
2. What is a tetrapod fracture?
The ZMC/zygomatic-orbital-maxillary complex fracture is often referred to also as the tripod fracture.
The described fracture in reality involves five bones and four areas of articulation. More accurately, it
may be described as a tetrapod fracture with the zygoma relating to the maxilla, frontal bone, greater
wing of the sphenoid, and temporal bone.
3. What are the muscular attachments of zygomatic bone?
Muscles of facial expression originating from the zygoma that are innervated by the facial nerve are the
zygomaticus major and minor muscles that insert to support the oral commissures and zygomatic head
of the levator labii superioris. The masseter muscle inserts along the temporal surface of the zygoma
and zygomatic arch. The temporalis muscle and fascia pass beneath the arch and attach to the coronoid process of the mandible. This fascia that attaches to the zygoma produces resistance to inferior
displacement of a fractured fragment that is exerted by the downward pull of the masseter muscle.
4. What are the fracture patterns of the ZMC?
ZMC fractures are second only to nasal fractures in frequency of involvement in facial fractures. It is
rare to get a true fracture of the zygomatic bone. Fractures usually occur at the suture lines where the
zygomatic bone meets the maxilla, frontal, temporal, and sphenoid bones. The zygoma may be separated from its four articulations; this almost always involves the orbital floor as well. These fracture
patterns usually lead to posterior and medial positioning of the zygoma that lead to facial flattening
and facial widening. Typically, the fracture line travels through the zygomaticofrontal (ZF) suture, into
the orbit at the zygomaticosphenoidal suture to the inferior orbital fissure. Anterior to the fissure, the
fracture travels through the orbital floor and infraorbital rim, goes through the infraorbital foramen,
and continues inferiorly through the zygomaticomaxillary (ZM) buttress. Posteriorly, the fracture
extends from the buttress and through the lateral wall of the maxillary sinus. Finally, one of the most
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329
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frequent patterns of fractures of the zygoma is isolated arch fracture, which occurs at its weakest
point, about 1.5 cm posterior to the zygomaticotemporal suture.
5. What are the classifications of ZMC fractures?
Classification pattern assists the surgeon in treatment planning of open versus closed reduction of the
fracture and the stability after fixation. There are several classification systems based on anatomic
displacement. Perhaps the most popular classification was by Knight and North in 1961. They used
the direction of displacement of zygomatic fracture on Waters’ view radiographs. With the advent of
the CT scan, more modern classification schemes have emerged. Manson and colleagues in 1990
proposed a classification scheme based on pattern of segmentation and displacement, while Gruss
and associates proposed a system that stressed the importance of recognizing and treating zygomatic
arch fractures in association with the zygomatic body. Zingg et al. in their 1992 review of 1025 zygomatic fractures proposed the following classification:
• TypeA:Incompletelow-energyfracturewithfractureofonlyonezygomaticpillar
• TypeB:Completemono-fragmentfracturewithfractureanddisplacementalongallfourarticulations
• TypeC:Multi-fragmented,comminutedfracturesofthezygomaticbody
6. What are the physical findings associated with ZMC fractures?
The ZMC forms the lateral wall, inferior rim, and floor of the orbit, and consequently, most
fractures involving this complex can be considered true orbital fractures. Initial evaluation involves
documentation of bony injuries and any injuries to surrounding soft tissue, including eyes, lacrimal
apparatus, and canthal tendons. Also important is detailed documentation of any cranial nerve injuries,
particularly to cranial nerves V and VII. Visual acuity and status of globe need to be investigated and
ophthalmology consulted as needed.
• Swellingandatteningofcheekalongwithperiorbitaledema/ecchymosis
• Downwarddisplacementofthezygoma,whichproducesananti-mongoloidslanttothelateral
• Subconjunctivalhemorrhage
• Stepdeformityandpointtendernessatzygomaticarch,inferiororbitalrim,zygomaticofrontal
• Inisolatedzygomaticarchfractures,adepressionisobservedandpalpatedanteriortothetragus.
• Flatteningofthemalarprominenceorzygomaticarch
• Epistaxisduetoinvolvementofmaxillarysinus
• Ifextensiveorbitalinvolvementexists,thereisapossibilityforpresenceofchangesinglobeposi-
• Visualdisturbancessuchasdiplopia,reducedvisualacuity,traumaticmydriasis,hyphema,and
• Ecchymosisinthemaxillarybuccalvestibule(Guerin’ssign)
• Trismusduetoimpingementofthecoronoidprocessbycollapsedzygoma
• Infraorbitalnerveparesthesiaduetoeitherdirecttraumaorimpingementfromthefracturedseg-
7. What ophthalmic injuries may be associated with zygomatic-orbital-maxillary
ZMC fractures are often accompanied by some degree of ocular injury, whether minor or major.
• Minorocularinjuriesincludesubconjunctivalhemorrhage,iritis,irissphinctertear,cornealabrasion,
• Majorocularinjuriesincluderupturedglobe,retinalhemorrhage,retinaldetachment,andhyphema.
8. What degree of vertical dystopia can be compensated secondary to ZMC/orbital
Diplopia following ZMC/orbital fractures is typically secondary to muscle entrapment/edema/fibrosis,
The clinical signs and symptoms of ZMC fractures can include:
canthus with accentuation of the supratarsal fold of the upper eyelid. Worm’s eye view evaluation
of facial symmetry is very useful.
suture, and zygomatic buttress region
tion, including evidence of vertical dystopia, enophthalmos, and inferior rectus muscle entrapment
resulting in restriction in the movement of extraocular muscles especially on upward gaze.
retinal tears
ments of bone
complex fractures?
Knowing this, it is imperative that the surgeon performs a thorough ophthalmologic examination and,
if deemed necessary, seek consultation with opthalmologist colleagues. Some of these are minor
ophthalmic injuries while others are major ones.
commotio retinae, and microhyphema.
fractures before causing binocular diplopia?
hemorrhage, or motor nerve palsies. The brain should be able to accommodate for a vertical dystopia
of up to 1 cm without causing diplopia in the primary fields of gaze.
CHAPTER 31 MANAGEMENT OF ZYGOMATICOMAXILLARY COMPLEX AND ORBITAL FRACTURES 331
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9. What is enophthalmos?
Enophthalmos may be defined as the posterior displacement of the globe that is often due to increase
in orbital volume secondary to interruption of the skeletal integrity of the bony orbit. Enophthalmos
may present immediately or may be delayed as resolution of edema over the course of the post-injury
period exposes underlying abnormalities. Deepening of the supratarsal fold and the presence of a
pseudoptosis are common clinical findings. The Hertel exopthalmometer is an instrument that may
be used for measuring the position of the globe in an anterior-posterior direction as referenced to
the contralateral globe and the lateral orbital rims. A difference of 2 mm is considered to be clinically
significant.
10. What are the radiographic findings associated with ZMC fractures?
Radiographic findings of ZMC fractures include the following:
• AxialandcoronalplaneCTisthegoldstandardforradiographicevaluationofzygomaticfractures.
It allows for detailed evaluation of buttresses of the midfacial skeleton including the orbit.
• Waters’viewisthesinglebestX-rayforevaluationofZMCfractures.ItisaPAprojectionwithhead
positioned at a 27-degree angle to the vertical. It provides good visualization of the sinuses, lateral
orbits, and infraorbital rims.
• Submentovertex(jug-handle)X-rayviewishelpfulforevaluationofthezygomaticarchandmalar
projections. Waters’ and submentovertex-ray views are rarely used. When they are used, it is often
in absence of or bypassing CT imaging but rarely in combination with CT.
11. What are the indications for treatment of ZMC fractures?
Surgical treatment is warranted in the presence of displacement, instability, or comminution of the
bony fragments. The patient’s age, personal desires, and medical status and the status of the globe
and of vision on the contralateral side all must be considered. Minimally displaced or nondisplaced
fractures often may be observed expectantly and require no acute surgical intervention. Minimally
displaced fractures or even moderately displaced fractures may be observed for several weeks for
the swelling to resolve while observing for the appearance of cosmetic deformities as edema resides.
Factors influencing a decision to surgically intervene are:
• Facialaesthetics.Itisdesirabletoreestablishthetypicalcontourofthefaceforamoresymmetric
look and to prevent complications such as facial dysmorphism, enophthalmos, and orbital dystopia.
• Protection:TheZMChasavitalabsorbentfunctioninthesafeguardoftheorbitandbrainduetoits
key anatomic location, which would make reestablishing its proper projection important.
• Functionalimpairment:Fracturesthatinterferewithocularfunction,infraorbitalnervefunction,or
normal mouth opening should be treated.
12. Is there a role for orbital floor exploration in all ZMC fractures?
By definition, ZMC fractures almost always have a variable amount of involvement of the internal
orbit. There has been debate over the risks/benefits of performing orbital floor explorations on these
injuries. It had been theorized that displaced fractures that had previously been deemed not to need
internal orbital exploration/reconstruction might benefit from reconstruction after adequate reduction of the medially displaced and rotated ZMC fracture. Current evidence suggests that status of
the internal orbit visualized on preoperative CT scan is a good indicator of the need for reconstruction and that reduction of the displaced ZMC fracture plays little role in increasing this need. The
surgeon must treat these injuries on a case by case basis, utilizing physical findings to help guide
the decision for internal orbital reconstruction rather than treating all injuries in a standardized
manner.
13. What are the optimal times for treatment of ZMC fractures?
ZMC fractures are not emergencies; any associated life-threatening injuries must be addressed first.
Open reduction should be performed if indicated before the onset of edema, or after waiting several
days for edema to decrease. Such delay is unlikely to compromise the surgical outcome and often
results in better surgical results as long as the delay does not extend beyond 2 to 3 weeks.
14. What are the principles of treatment of ZMC fractures?
Conservative treatment is indicated if there is minimal or no displacement of the fractured bones, or in
cases involving the elderly or medically compromised patients. The main objectives of surgical treatments are accurate anatomic reduction of the displaced bones and buttresses and, where indicated,
stable fixation of reduced fractures to reestablish form and function. Surgical reduction is either by
fracture reduction without fixation or by open reduction and internal fixation (ORIF).
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