GITAM DENTAL COLLEGE & HOSPITAL

DEPARTMENT OF

ORAL & MAXILLOFACIAL SURGERY

SEMINAR ON

Midfacial fractures

Presented By:

Dr. Sambhav K Vora

III MDS

CONTENTS

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I. INTRODUCTION

II. DEFINITION

III. HISTORY

IV. MIDDLE THIRD BONES

V. PHYSICAL CHARACTERISTICS

VI. ARTICULATION WITH BASE OF SKULL

VII. BIOMECHANICS

VIII. CLASSIFICATIONS

IX. LE-FORT I,II,III FRACTURES

X. PALATAL FRACTURES

XI. EXAMINATION

XII. MANAGEMENT

XIII. VIEWING OF IMAGES

XIV. CLASSIFICATION OF METHODS OF MAX.FRACTURE

FIXATION

XV. USE OF DIFFERENT TYPES OF INTERNAL WIRE SUSPENSION

XVI. FIXATION TECHNIQUES

XVII. SURGICAL APPROACHES TO EXPOSURE OF MAXILLA

XVIII. COMPLICATIONS

XIX. CONCLUSION

XX. REFERENCES

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INTRODUCTION

Fractures of the maxilla and associated bones were commonly referred to as

fracture of the middle third of the facial skeleton.

The reconstruction of the midface following trauma demands

uncompromising care. The phase is intimately related to self image. It is the

region responsible for our sense of smell,vision & for providing our voice &

its resonance through the presence of air sinuses.

DEFINITION OF MIDDLE ONE THIRD OF THE FACE:

The middle third of facial skeleton is defined as an area bounded superiorly

by a line drawn across the skull from zygomaticofrontal suture across the

frontonasal and frontomaxillary sutures to zygomaticofrontal sutures on the

opposite side and inferiorly by the occlusal plane of the upper teeth. It also

extends backwards as far as the frontal bone above and the body of sphenoid

below and pterygoid plates of the sphenoid below

MIDDLE THIRD OF FACIAL SKELETON IS MADE OF:

Maxillae

Zygomatic bones

Zygomatic process of temporal bones Paired bones

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Palatine bones

Nasal bones

Lacrimal bones

Vomer

Ethmoid and its attached conchae

Two inferior conchae

Pterygoid plates of sphenoid

The relative fragility of the mid-facial skeleton acts as a cushion for trauma

directed towards the cranium from an anterior or anterolateral direction.

ARTICULATION WITH THE BASE OF THE SKULL:

It is known that the frontal bone and body of sphenoid form an inclined

plane which slopes downwards and backwards from the frontal bone at an

angle of about 45° to occlusal plane of upper teeth. The bones of the middle

third of facial skeleton articulate with these strong foundation bones and

when fracture occurs there is backward and downward displacement causing

the posterior teeth and maxillae to push open the mandible producing a

gagging of occlusion posteriorly. In extreme cases the soft palate may be

pushed down upon the dorsum of the tongue causing embarrassment to the

airway. The fractures usually follow the lines of weakness within the face

described classically Guerin (1866) and Lefort (1901).

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CLASSIFICATION:

A. FRACTURES NOT INVOLVING OCCLUSION:

I. Central Region:

a. Fractures of the nasal bones/nasal septum.

Lateral nasal injuries

Anterior nasal injuries

b. Fractures of frontal process of maxilla

c. Nasoethmoidal fractures

d. Fractures of type (a), (b) and (c) extending into the frontal bone

(frontoorbitonasal dislocation).

II. Lateral region:

Fractures involving the zygomatic bone, arch and maxilla excluding

dentoalveolar component.

B. Fractures involving the occlusion :

Dentoalveolar

Subzygomatic

- Lefort I (low level or Guerin)

- Lefort II (Pyramidal Fracture)

Suprazygomatic

- Lefort III (High level or craniofacial dysfunction)

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MODIFIED LEFORT FRACTURE CLASSIFICATION :

LeFort Level Description

I Low maxillary fracture

la Low maxillary fracture with multiple segments

II Pyramidal fracture and nasal fracture

IIb Pyramidal and NOE fracture

III Craniofacial dysjunction

IIIa Craniofacial dysjunction and nasal fracture

IIIb Craniofacial dysjunction and NOE

IV Lefort II or III fracture& cranial base fracture

IV a + supra orbital rim fracture

IV b + anterior cranial fossa and supra orbital rim

fracture

IV c + anterior cranial fossa and orbital wall fracture

FRACTURE PATTERNS

Rene Lefort -1901 gave a classification based on his study of the lines of

weakness present on the human skull.

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LeFort I: A horizontal fracture above the level of the nasal floor. The

fracture line extends backwards from the lateral margin of the anterior nasal

aperture below the zygomatic buttress to cross the lower third of the

pterygoid laminae. The fracture also passes along the lateral wall of the nose

and the lower third of the nasal septum to join the lateral fracture behind the

tuberosity.

LeFort II: Fracture runs from the middle area of the nasal bones down either

side, crossing the frontal process of the maxillae into the medial wall of each

orbit. Within each orbit the fracture line crosses the lacrimal bone behind

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the lacrimal sac before turning forward to cross the infraorbital margin

slightly medial to or through the infraorbital foramen. The fracture now

extends downwards and backwards across the lateral wall of the antrum

below the zygomatico maxillary suture and divides the pterygoid laminae

about half way up.

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Lefort III: The fracture runs from near the frontonasal suture transversely

backwards, parallel with the base of the skull and involves the full depth of

the ethmoid bone, including the cribriform plate within the orbit the fracture

passes along below the optic foramen into the posterior limit of the inferior

orbital fissure. From the base of the inferior orbital fissure the fracture line

extends in two direction; backwards across the pterygomaxillary fissure to

fracture the roots of the pterygoid laminae and laterally across the lateral

wall of the orbit separating the zygomatic bone from the frontal bone.

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Stanley and Nowak (1985) in a cephalometric study of cadaver facial

impacts stressed the importance of the angle of impact in relation to the

horizontal buttresses of the facial skeleton.

Impacts on the nasion at 30°-60° above the horizontal are likely to cause a

Lefort III fracture.

A horizontal impact whose vector is in the horizontal orbitomental plane

tends to cause LeFort II fracture.

Impacts below the anterior nasal spine tends to detach the hard palate and

maxillary alveoli from the nest of the midface.

This time honored classification does not provide full description of the

degrees of comminution and displacement, nor does it mention two

commonly associated and very important lesions the parasaggital fracture of

the upper jaw. Furthermore the severity of maxillary fracture to other areas

of the craniofacial skeleton.

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Cooter S.David (1989) classified the fracture of the facial skeleton.

Main bones of the skull was classed as (Major zones) and the sutures,

various bone parts are classed as (Minor Zones).

In case of maxilla.

Major Zone : Maxillary bone as a whole.

Major code of maxilla : MX.

Minor zone : Anterior wall of maxilla, buttresses, palate, dentoalveolar and

pterygoid.

Minor code : MxA, MxB, MxP, MxD, MxT.

Severity of Fracture:

No fracture : 0

Undisplaced fracture : I

Obviously displaced fracture : 2

Comminuted/Compound fracture : 3

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BIOMECHANICSButtresses form basic vertical and horizontal framework for facial skeletonImp. Facial structures – orbit and paranasal sinuses are surrounded by buttressesManson et.al4 vertical – 3 bilateral. Peripheral 1 central3 horizontalWithstand vertically directed forcesPoorly suited – horizontally or ventrally directed forces

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VERTICAL BUTTRESSES

3 Bil peripheral :

Nasofrontal buttress

Frontal process of maxilla

Nasal bones

Nasofrontal suture

Med.wall of max.sinus & orbits

Forms a bridge between anterior hard palate and frontal

bone

zygomatic buttress

body of zygoma and its frontal process

transmit forces from mid-maxilla to frontal bone

pterygomaxillary buttress

pterygoid process & plates of sphenoid bone

posterolateral & posteromedial walls of

adjacent maxillary sinus

transmit forces from posterior hard palate and

alveolar ridges to the base of skull

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1 Central :

Nasoethmoid Buttress

Ethmoid

Vomer Bone

Forms an important osseous bridge between

lower facial skeleton and the cranium

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HORIZONTAL BUTTRESS

• Inferior buttress

alveolar ridge

hard palate

acts as important stabilizing bridge between the two maxillary bones

• Superior buttress

orbital plate of frontal bone

cribriform plate of ethmoid bone

• Middle buttress

zygomatic process of temporal bone

body & temporal process of zygoma

infraorbital process of zygoma

orbital surface of maxilla

segments of frontal process of maxilla

provides lateral stability to facial skeleton

protects central facial skeleton from horizontally directed

forces

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CLINICAL FEATURES OF INDIVIDUAL FRACTURE :

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LEFORT I, LOW LEVEL OR GUERIN TYPE FRACTURE :

May occur as a single entity or in association with Lefort II and III fractures.

A Lefort I fracture which often escapes diagnosis is the impacted type which

results from violence transmitted via a blow to the lower jaw and is often

therefore associated with a fracture of the mandible. It is possible to see the

condition unilaterally when it involves only one maxilla, the tooth bearing

portion being split along the median palatal suture.

Clinical Features:

Upper lip laceration, loose or fracture maxillary incisors.

Airway obstruction - (+/-)

Edema of the upper lip and (laceration +/-)

Lengthening of the face - may or may not be present depending whether the

fracture is impacted or not.

Epistaxis-(+ve)

Nasal septal deformity may or may not be present

Impacted type of fracture may almost be immobile but implication will be

present, usually caused from trauma transmitted via a blow to lower jaw

where lower teeth come and hit against the maxillary teeth.

Occlusion is disturbed and a variable amount of mobility may be found in

tooth bearing segment of maxilla due to dentoalveolar fracture if present.

Echymosis will be present in buccal vestibule.

On percussion of the upper teeth there will be distinctive cracked pot sound.

ln case of a fracture coursing through the palatal suture line or adjacent to it

a palatal echymotic area is usually noted.

SYMPTOMS:

Initial hemorrhage from nose or mouth.

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Teeth meet abnormally.

Pain on mastication.

Maxillary mobility with swallowing.

Trismus

Nasal obstruction, upper airway obstruction

Dysphagia

SIGNS:

Lip laceration, lose or fractured maxillary incisors.

Lower maxillary asymmetry, malocclusion

Gingivobuccal sulcus echymosis of tenderness

Septal tear or dislocation

Facial elongation, cracked pot sound

Subcutaneous emphysema and crepitus

Oropharyngeal edema and hematoma

Opaque antrum on transillumination

Radiographs:

OPT, PA skull. Lateral skull, PNS.

LeFort II or Pyramidal Fracture :

Referred to as a pyramidal fracture with the apex of the pyramid being the

nasofrontal suture. Classic manifestation of this fracture is bilateral

periorbital edema at times accompanied by echymosis giving rise to

Racoon's sign.

Clinical Features: Gross oedema of the middle third of facial keleton.

1) Airway obstruction : ±

2) Cerebrospinal fluid leak : ±

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3) Crepitus : ±

4) Decreased extraocular muscle function : ±

5) Diplopia : ±

6) Echymosis, buccal vestibule : +

7) Periorbital echymosis : +

8) Subconjuctival echymosis : +

9) Enopthalmoid : ±

10) Bilateral epistaxis : +

11) Infra orbital rim defect : +

12) Lengthening of the face with disk face deformity : + (Moon face)

13) Malocclusion : +

14) Medial canthal defomuty : ±

15) Nasal septal defoimity : ±

16) Pupil height, unequal : ±

17) Lateral orbital rim defect : (-)

18) Anaesthesia/Parasthesia of tile cheek : ±

19) Posterior gagging of occlusion due to retropositioning of maxilla: +

Radiographs : PA skull, Submentovertex, Labial skull. Water view, CT

Scan.

LE FORT III :

Also called as the craniofacial dysfimction. The symptoms are classic dish

face and the mobility of2ygomaticomaxiUary complex.

Gross oedema of the soft tissues over the middle third of the facial skeleton

(+)

Airway obstruction (±)

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Cerebrospinal fluid leak (±)

Crepitus (+)

Decreased extraocular function (±)

Diplopia(±)

Periorbital echymosis(+)

Subconjunctival echymosis (+)

Endopthalmos(±)

Bilateral epistaxis (+)

Labial orbital rim defect (+)

lengthening of face (±)

Trismus (±)

Malocclusion (+)

Medial canthal deformity (±)

Nasal septal deformity (±)

Parasthesia of anterior cheek (+)

Pupil height unequal (±)

Epiphora (±)

Telecanthus (±)

Radiographs : PA skull, Submentovertex, Lateral skull. Water's view, CT

scan.

Airway obstruction with stridor or dysphagia may arise from either sagging

of the soft palate against the tongue or posterior oropharyngeal wall edema

or hematoma caused by sudden impact of the posterior margin of the hard

palate against the cervical spine, also it may be due to presence of clots and

debris like bone or tooth fragments.

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In some cases the direction of the traumatizing force and subsequent pull of

both gravity, pterygoid muscle action and superior constrictor muscle

combine to produce a degree of posterior displacement and inferior tipping

of the fragments.

Lengthening of the face can be then if fracture fragments is free floating and

percussion of teeth will have cracked pot sound.

In LeFort III fracture due to bilateral separation of frontozygomatic sutures

causing lengthening of the face and lowering of the fracture fragment

bilaterally and lowering of the occular level due to fracture passing above

the withnall's tubercle removing the support given to the eye by suspensory

ligament oflockwood.

A para saggital split usually occurs in 10% of LeFort fracture. The fracture

line is usually within I cm of but not within the midline. The vomer

strengthens the midline of the palate and the alveolar process provides the

bulk laterally. Therefore the fracture is through the thin bone just off the

saggital plane. Therefore a linear echymosis of the overlying mucosa

fracture line may be palpable and two side can be moved independently.

CSF RHINORRHEA :

CSF rhinorrhea results from a breakdown of the dura and supporting

structures of the skull base resulting in a connection between the

subarachnoid space and the nose. It may be a complication of trauma, tumor

ablation, paranasal sinus disease, or surgery. Regardless of etiology, the

mechanism is essentially the same. There is a disruption of the arachnoid

and the dura, coupled with an osseous defect, and a CSF pressure gradient

that is either continuously or intermittently greater than the healing tensile

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strength of the disrupted tissue. This causes separation of the dural fibers and

CSF leakage.

CSF rhinorrhea may occur directly through the anterior cranial fossa or

indirectly from the middle or posterior fossa via the Eustachian tube. More

specifically, these portals of entry may take place across the frontal sinus,

cribriform plate of the ethmoid, the sphenoid sinus, the sella, or via the

temporal bone from the middle ear and through the Eustachian tube.

C.S.F. OTORRHEA:

If an intact tympanic membrane ruptures (CSF) fluid will leak out of the ear

resulting in (CSF) otorrhea. Loss of hearing is frequently associated with

collection of fluid in the middle ear cleft. Anosmia is associated with tear in

the area of the cribriform plate. If this symptom can be localized to one side

of the nasal fossa or the other it can sometimes be of value in localizing the

leak problem.

If (CSF) rhinorrhea is straight forward if the fluid is not mixed with blood,

nasal secretions or lacrimal secretions it should be collected in a vial and if

glucose level analysis of 45 mg/dl confirms (C.S.F.).

CSF Nasal Secretions Serum

Glucose (mmoles/lit) 2.5-3.9 0.6-1.4 3.5-52

Protein (g/lit) <0.5 >2 60-85

K (Mmoles/Lit) 2.5-3.5 12-26 3.3-4.8

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C.S.F. will not stiffen a hand kerchief, while nasal secretion will do so.

C.S.F. will also form characteristic concentric rings when poured on linen or

tissue paper. Patient should be questions about any salty taste.

It should be noted that absence of leakage does not imply the absence of

leakage does not imply the absence of a tear of dura. Meningitis is the

inherent risk is a basal skull fracture with a concomitant dural tear. Mulec

reported a case of cerebrospinal fluid rhinorrhea 12 years following injury.

The presence of a basilar skull fracture with a dural tear is not a

contraindication to the reduction of midface fractures. On contrary a mobile

midface often creates a pumping action that results in increased CSF

leakage. Early reduction and immobilization are therefore indicated.

Epiphora :

Post-Traumatic Enopthalmos :

Diplopia :

Hooding of the Eye :

The suspensory ligament of Lockwood which is a fascial sling posses from

medial attachment in the region of the lacrimal bone to be inserted laterally

into whitnall tubercle on the lateral wall of the orbit just below the

frontozygomatic suture. If fracture posses above the Whitnalis tubercle the

zygomatic bone is displayed downwards and the upper eyelid follows it

causing a characteristic hoarding of the eye.

Anaesthesia/Parasthesia :

Of the anterior cheek can be can be due to trauma to the

infraorbital nerve. Subsequent oedema of the middle 3nl of the face also

contributes to parasthesia of that region.

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POST-TRAUMATIC TELECANTHUS :

Medial canthal ligament is attached to the anterior and posterior lacrimal

crest. Any injury due to trauma to the nasoethmoidal area causing fracture

of the bones with comminution the fracture fragments will spread laterally

into the orbital space. Comminution of the lacrimal bone or avulsion of

ligaments from the lacrimal crest or direct laceration of die medial canthus

would cause displacement of medial canthal ligament laterally. The tension

exerted by the orbicularis oculi muscle, now unchecked due to displacement

of (M.C.L.) well result in rounding of the medical canthus and a shortening

of the horizontal palpebral fissure. Lateral migration of the canthus will than

obscure the camucnie and alter the angle set by the lids at the medial

canthus, detachment of Homer's muscles which maintains the backward pull

of the lid will cause a laxity and excessive scleral show. Measuring the

interpupillary distance and dividing it by half will give us the approximate

intercanthal distance. Telecanthus thus is the term applied for widening of

the medial canthus.

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HYPERTELORISM :

Is the term applied for bony displacement of the whole orbit (usually

observed with a congenital bone deformity). Normal intraorbital distance i.e.

distance between medial walls of the orbit) is usually less than 25 mm in the

adult female and 28 mm in adult male.

VIEWING THE IMAGES

Mc gregor and Campbell (1950) described rgstem for examining the OM

view by following four lines :

1. the first line: run across the zygomatic frontal sutures ,the frontal

sinuses and the superior margins of the orbit.

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2. the second line: runs along the zygomatic arches,the inferior margins

of the orbits and the nasal bones

3. the third line: crosses the mandibular condyles and coronoid process

and the maxillary sinus

4. the fourth line runs along the occlusal plane of the teeth and crosses

the mandibular rami.

5. Trapnell (1985) added a fifth line which runs along the inferior border

of the mandible.

DOLAN’S LINES FOR THE MODIFIED CAUD WELL

PROJECTION:

the first extends along the outer margin of the orbital process of the

frontal and zygomatic bones

the second line is the innominate line or oblique orbital line

the third extends along the inner margin of the orbit down to break

into 2 roughly parallel lines meeting at the inferior orbital fissure . the

line then continues along the orbital margin inferiorly ,internally and

superiorly

the fourth runs along the occlusal plane of the teeth and crosses the

mandibular rami.

Dolans lines for the OM projection:

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1. the “orbital line”: extends along the inner margins of the lateral,

inferior & medial walls of the orbit ,passing over the nasal arch to

follow same structure on the opposite side.

2. the zygomatic line: extends along the superior margin of the arch and

body of the zygoma passing along the lateral margin of the frontal

process of the zygoma to the zygomatic frontal suture

3. the maxillary line: extends along the inferior margin of the zygomatic

arch, the inferior margin of the body and buttress of the zygome and

the lateral wall of the maxillary sinus.

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29

30

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PALATAL FRACTURES:

Fractures of the palate present a unique challenge to the surgeon skilled

in conventional management of mid fractures. These unstable fractures are

an Infrequent finding in the maxillotacial trauma patient. Most often palatal

fractures are associated with other fractures of the midrace. They are found

8% of Le Fort fractures, and rarely are they found as an isolated fracture.To

ensure proper postoperative stability and restoration of preinjury occlusion, a

staged surgical approach is required for each class or palatal fracture.

DIAGNOSIS

Today with many trauma centers equipped with highly accurate CT

scanners, few palatal fractures go undiagnoscd. This imaging modality is

especially important in diagnosing those palatal fractures that are not

associated with any clinical signs indicative of this type of fracture.

Most patients having palatal fracture will demonstrate clear signs and

symptoms. In up to 65% of palatal fractures, the patient will demonstrate a

laceration of the lip, with 45% concurrently possessing both palatal and

gingival mucosal disruption.15 A change in the maxillomandibular occlusal

relationship is also a reliable indicator. Segments of a fractured palate arc

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most often found to be displaced in both an anterior and a lateral direction. l6

The surgeon should be cautioned against using occlusion as an indicator of

the presence of a palatal fracture, because the fracture may be masked by a

concurrent mandible fracture, which itself produces marked rotation and

displacement of its fractured fragments.

CLASSIFICATION

Six patterns of palatal fractures have been dccribedls based on their

relationship with the maxillary alveolus, teeth, and palatal midlinc

Type I—Alveolar fracture (2 types)

Type la—Anterior alveolus—contains only the incisor teeth and alveolus in

that region

Type Ib—Posterolateral—contains premolars, molars, and alveolus in that

region

Type II—Sagittal fracture

Type II fractures occur as a midline split of the palate. These types are found

with the most frequency in the second to third decade because of a lack of an

ossified midline palatal suture.

Type III—Parasagittal fracture

Most common fracture found in adults (63%) because of the thinner palatal

bone located parasagittally.These fractures are differentiated from type Ib

fractures because they contain the canine in addition to the premolars and

molars.

Type IV—Paraalveolar fracture

Found directly palatal to the maxillary alveolus and also contains the incisor

dentition.

Type V—Complex/comminuted fracture

Multiple large, obliquely oriented fracture segments or gross comminution

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Type VI--—Transverse

The rarest palatal fracture found, ir divides the maxilla

in a coronal plane.

TREATMENT

The approach to surgical treatment of palatal fractures begins with the

identification of the specific type of fracture, state of the dentition, and

associated maxil-larv or mandibular fractures. Predictable treatment is

performed when using the combination of rigid internal fixation, application

of arch bars, and a palatal acrylic splint in complex fractures.

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MANAGEMENT :

35

Once the (ABC) of primary trauma management has been satisfied

and after a history has been noted the initial clinical examination is done,

starting with a brief visual inspection of the facial structure followed by

palpation to locate any evidence of fractures. Radiology plays a critical role

in the precise diagnosis of fractures. Additional information can be

obtained with (CT) scanning. Bleeding from laceration must be controlled

by pressure or placing sutures at the site. Bleeding from the ear can be due

to associated condylar fractures causing laceration along the anterior wall of

the canal. A perforation or bluging of the tympanic membrane usually

indicates a basillar skull fracture. Subconjunctival haemorrhage reflects an

orbital or periorbital injury. Of similar importance is the evaluation of the

nose particularly the septum which may have septal haematoma if present

haematoma should be trained to avoid septal necrosis and ultimately

development of septal perforation. Even watchout for CSF rhinorrhea

which results from the fracture involving the base of the skull and escape of

CSF to either the ethmoid, sphenoid, frontal sinus or cribriform plate areas.

Bilateral periorbital echymosis is commonly seen as a result of fracture of

the base of the anterior cranial fossa and also is known as the racoons sign.

Echymosis in the buccal fold frequency indicates a fracture of the maxilla of

the zygoma or in an isolated fracture of the lateral wall of the maxillary

sinus. Crackling sound in the subcutaneous tissue indicates subcutaneous

emphysema which may be due to the passage of air throughout the fractured

wall of maxillary sinus. Test for infraorbital nerve anesthesia as the nerve

can be damage in case of Lefort II or as a result of orbital blow out fractures.

Anosmia as a result of midfacial fracture involving the cribriform plate may

occur , this may be due to the transsection of olfactory nerves and can be

permanent. Injury to the intracranial course of occulomotor nerve resulting

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in compression of the nerve may lead to dilated peoples indicating the

cranial nerve III dysfunction. Lateral rectus muscle dysfunction or lateral

gaze dysfunction usually indicates involvement of abducent nerve. Fracture

of bones surrounding the optic foramen results in compression of optic

nerve. In unconscious patient optic and occulomotor nerve function can be

evaluated by using the consensual light reflex. Echymosis in the maxillary

buccal fold and a class III open bite malocclusion are indicative of maxillary

fracture. A direction and force of injury usually drives the maxilla

posteriorly and inferiorly resulting in this occlusal deformity. Nasofrontal

suture region should be palpated firmly when the maxilla is manipulated to

exclude Lefrot II and Lefort III maxillary fractures. The thumb and index

finger can be used for palpation in the buccal fold region as the maxillary is

manipulated by placing one hand on the forehead while manipulating the

maxilla with other. Lack of maxillary mobility does not exclude a maxillary

fracture always depending on the direction and force of injury a maxillary

fracture may be significantly impacted and mobilization may be possible

only after the patient has been anesthetized and disimpaction forceps has

been used. Significant displacement of lateral orbital rim may result in

diplopia secondary to displacement of the lateral canthal ligament. Patient's

visual acquity and extraocular movements must be reevaluated as a part of

periorbital examination. Intraoral palpation of the buttress may disclose a

step deformity. Intracanthal width normal 30 to 30 mm although slight

racial variation exists, measurement beyond 32 mm generally indicates the

presence of traumatic telecanthus. Although traumatic telecanthus is not

associated with diplopia or other regional changes it would result in

cosmetic deformity. The triad of a flattened nasal bridge, and obtuse medial

canthal angle and increased intercanthal angle should alert the clinician to

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tile presence of deformity. Palpation of nasofrontal suture will reveal

repetition and pulling the soft tissue laterally into the lateral canthal angle

region results in rounded or semi lunar crease rather than a sharp canthal

angle. Traumatic telecanthus is easily differentiated from hypertelorism in

which the interpupillary distance is increased normally 60 to 65 mm.

Hypertelorism is generally seen in congenital deformities such as Crouzon's

disease and Apert's syndrome and rarely is a result of trauma. Large number

of muscles attached to the walls of the maxilla but these insert only into the

skin and do not contribute to the deformity of the fracture. Perigoid muscles

in case of Lefort fractures usually act on die fracture fragments and pull

them posteriorly and laterally. Intraorally after checking for mucosal

lacerations, subrnucosal echymosis, status of teeth, integrity of palate and

upper alveolus should be evaluated. A split palate may be often be

associated with laceration and separation of alveolar rim. Premature contact

of molar teeth and an openbite deformity is due to displacement of the whole

maxilla backward and 2< downwards. Whereas crossbites are apparent with

lateral displacement of the maxilla in case of a split palate.

The examination is usually carried out with a gloved finger which is passed

on to the hard palate exerting an upward and rocking force which may

elicited pain, crepitus and abnormal mobility. Further examination of other

sites using bimanual palpation at pyriform base and nasofrontal and fronto-

zygomatic suture areas in turn while applying upward rocking force to the

hard palate. In some cases of patients with gross midface instability can be

demonstrated by asking the patient to bite upwards with his mandible

resulting in upward movement of the upper jaw.

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Preoperative planning of whether open or closed method one to be

employed, following this decision the type of fixations selected following

which the necessity for and type of intermaxillary fixation depending upon

the condition of the teeth, presence of alveolar or palatal fractures will

influence the choice between interdental eyelet wires, arch bars, gunning

type of splints.

Usually the surgery may be delayed until the patient's condition has been

stabilized and the swelling has largely settled though many controversies are

present regarding early or late management.

TREATMENT :

As in the treatment of any other fracture the objective with a fracture of the

middle of the face is to achieve reduction followed by an adequate period of

fixation to ensure stable union.

Facial skeleton can be broadly divided into three concentric rings. The outer

ring or framework of the face is reconstructed first by reducing the frontal

bone and orbital roof, zygomatic complex on each side and establishing a

mandibular platform below. Now the central block can be reduced and

mixed within it utilizing the occlusion below and direct fixation to the

cranium above. The most control ring comprises of the nasal complex on

each side.

After using the mandible as a guide to accurate reduction, the middle third

must be immobilized by attaching it to a fixed point on the vault of the skull.

Treatment of Unilateral Maxillary Fracture :

39

If fracture fragment is mobile digital pressure may be utilized to reduce the

fracture. The teeth in fracture segment are first loosely wired to the

maxillary arch bar. The teeth in the unfractured segment are securely ligated

(I.M.F.) is carried out on the unfractured site and completed on the fractured

side after reduction and lightening of interdental wires of that fragment

(IMF) is released after 4 weeks by which time satisfactory stabilization will

have observed.

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Occlusal splints can also be used. Arch bars are placed on both

maxillary arches. The maxillary bar is cut at the line of fracture. The

interdental splint is wired first to stable fragment and the fracture portion of

arch is manually reduced into the splint and secured with a 24 gauge wire.

The mandible is then positively guided into the splint and (IMF) is

completed. Reduction is usually attamed with minimal difficulty especially

if carried out soon after the injury. On occasional, impacted fracture are

encountered which may not be responsive to digital manipulation. Here

Rowe's disimpaction forceps is an excellent tool for achieving reduction. An

open reduction may be utilized if fracture fragment appears to be unstable

following attempted reduction. An open reduction may be utilized if

fracture fragment appears to be unstable following attempted reduction. In

this case application of arch bans and an occlusal splint is necessary prior to

the placement of interossoeus wiring or bone plates. With rigid fixation in

place there is no need for the patient endure (I.M.F.). Teeth in the line of

fracture are lefr in place unless there is excessive mobility or unless the

fracture has occurred through the coronal 2/3'd of the tooth. An edentulous

minimally fracture hemimaxilla demands only digital reduction of the

garments. However when the fractured fragment contains teeth and the

unfractured one is edentulous, therapy comprises an open reduction and the

use of interosseous wiring or semirigid plate fixation.

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An early reduction of fracture as a rule presents minimal difficulty. Beyond

7 to 10 days increasing force has to be applied to complete a reduction. A

minimally displaced fracture is reduced and immobilized by intermaxillary

wire fixation. One month of immobilization is usually sufficient for healing

to occur. In the case of severe commination it may be necessary to extend

the period I to 6 weeks. An impacted fracture one not easily reduced because

of early fibrous union should treated by die use of either a Rowes or Hayton

Williams disimpactions forceps the beaks of the Rowes forceps are placed

along the nasal floor and against the palate. They are used a pair or singly.

To protect the nasal mucosa and the palatal mucoperiosteum, it is wise to

place rubber tips on the beaks. By means of a rocking and rotating motion

will usually recalcitrant maxilla. An open reduction has to be used when a

delayed reduction or severe impaction resists closed reduction methods. The

site of fracture is surgically exposed and the fracture liens are again followed

using a chisel. Use of a Rowe or a Hayton Williams forceps can be used

after that to complete the last of reduction. After that fixation can be done.

In cases of Lefort II and III fracture reduction of fracture is done in the

above mentioned ways. On occasion the superior aspect of the complex is

unstable owing to comminution of adjacent nasal bones, orbital floor and

medial orbital wall. The signs of entrapment of the orbital contents are noted

and the appropriate wall should be explored to free the entrapment.

Fractures should be mobilized and fixation done small defects are connected

by placement of a homologues graft. Large defects are treated by an

autogenous tip bone graft.

If the defect is so large that the bone graft has no shelf on which to set a

graft than a Steinmann pin is driven through the infraorbital rim and into the

medial and lateral walls forming a base on which to set the graft.

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Antral packings can be carried out in case of orbital floor fracture via a

Caldwell-Luc approach which provides an useful method for treatment of

comminuted body rim fracture also. A '/2 inch iodoform gauze preferably

run through antibiotic ointment is packed into the antrum and left for 3

weeks and then removed. The sinus is irrigated copiously for another I week

and then closed.

SAGITTAL MAXILLARY FRACTURES:

In reconstruction of the maxillary arch it can be difficult to restore the

correct width and projection in sagittal maxillary fractures. Prior

stabilization of the zygomatic arches creates another outer facial frame and

establishes the correct buttress figuration, so that the displaced sagittal

fractured maxilla an be put into its proper position. When the mandible is

made intact by intermaxillary immobilization the maxillary arch can be

positioned anatomically. Atransversal lag screw under the nasal anterior

spine, or miniplates horizontally across the sagittal fracture, can be helpful.

The palatal fracture can then be exposed and plated.

In the edentulous patients it is important that correct vertical posterior facial

height be established so that dentures can be fitted in the future. If possible

a gunning split is made from the patient's denture, if not available then a

splint made from models cast from dental impression of edentulous jaw

should be used. These splints are wired to the upper and lower jaws and then

to each other during surgery for a close reduction of fracture in both anterio-

posterior and vertical planes.

CLASSIFICATION OF METHODS OF MAXILLARY FRACTURE

FIXATION:

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I. Internal fixation :

a) Direct osteosynthesis

i Miniplates and screws Preferred methods of treatment

ii Wires

b) Suspension wires

i Frontal central or laterally placed (Kufiler)

ii Circumzygomatic (Cubero)

iii. Zygomatic Ancillary methods

iv. Cirumpalatal/ Palatal screw of treatment

v Infraorbital

vi Piriform aperture (Adams)

vii Peralveolar

II. External Fixation :

a) Cramomandibular

b) Craniomaxillaly

i) Supra orbital pens

ii) Zygomatic pins Less frequently use

iii) Hala frame

iv) Levant frame

Use of different types of internal wire suspensions.

1. Frontal

a. Central - used for Lefort II and III (Mandible is unstable).

b. Lateral - used for LeFort II and III where mandibular stable.

II Circumzygomatic - Lefort II and I

III Zygomatic - LeFort I

IV Infraorbital, Pyreform aperture - LeFort I

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Pyreform Aperture.

V Transnasal : Gunning splint

VI Per-alveolar : Gunning Splint

FIXATION TECHNIQUES :

EXTERNAL FIXATION APPLIANCE ON A HEAD CAP :

When internal fixation of the maxilla is not possible, external fixation

can be applied on a head cap using a Kingsiey splint or Wassmund

Hirschgeweih (antlers).

Metal side bars, fitted into square tubes on the maxillary splint or maxillary

denture, are directed outward through the angle of the mouth and parallel to

the buccal surface in the dorsal direction and attached to a plaster head cap

by means of elastic bands or rigid plaster connecting bars. The plaster cap

can be combined with an extension bar for continuous fraction on the

fractured parts by way of rigid or spring supported auxiliary elements. These

methods are really only of historical significance.

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46

EXTERNAL FIXATION BY A HALO FRAME :

The halo frame is a steel or titanium ring which is screwed to the skull for

fixation. The apparatus is constructed on the principle of the head frame

used in neurosurgeiy for stereotactic operations. Traction and fixation

elements can be attached to the ring, which surrounds the entire skull in the

manner of a halo. In principle, he halo frame can be used wherever the

plastic head cap is appropriate, especially in multiple fractures of the

midface. In contrast to the combination of splint side bars, elastics, plaster

connecting bars and a head cap, with its many possibilities for fracture and

maxillary displacement during healing, the halo frame is safe and more

comfortable for the patient. Its advantages are stability and variability. With

a halo frame specific regions can be extended without interfering through the

mandible and adjustment is easy. The disadvantage is the clumsiness of the

apparatus and its marital appearance. However, it is very surprising that

patients are not seriously incon\ nienced by this device, and it is more

comfortable than a head cap.

The halo frame may be fixed to the skull under local anesthesia. For

hygienic reasons the hair should be cut as short as possible. In general 4 to 5

screws are used to fix the frame, 2 in the occipital region and 2 or 3 in the

anterior part of the skull. The screws placed through the frame must be

inserted directly into the bone.

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The halo frame is indicated for repositioning the maxilla when no treatment

is possible immediately after injury, so that the maxilla is springly fixed

after 2 or 3 weelcs and is not mobile enough for surgical replacement and

bony fixation. Using elastic and springs applied on intraoral splints or

transbuccally by ire traction, the maxilla can be slowly repositioned and held

in position either for healing or for surgical treatment by intraosseous

wiring, suspension wiring or plating.

A similar result can be obtained using a Le Vant frame. However, this relies

on two supraorbital pins to locate the cranial fixation. Although this is very

rigid, it is not always possible to use it in severe craniofacial trauma. These

systems can only control the fractures at an occlusal level, and are rarely

indicated.

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49

INTERNAL FIXATION BY WIRE SUSPENSION :

Internal wiring suspends the maxilla from the mobile part to a fixed point of

the non-fractured skull from stable skeletal points into the oral cavity; these

are fixed on both sides on the arch bars under traction (craniofacial

suspension). The following suspension techniques are common frontomalar

suspension, suspension on the glabella, pirifonn aperture wiring, infraorbital

wiring, and circumzygomatic wiring. The limitations of wire suspension are

the incomplete exposure and the use of compression with suspension wires,

which carries the possibility of shortening the midface by compression in

cases with multiple fragments. Suspension wires provide only a single point

one 29 dimensional force of application. Three dimensional stabilization is

only achieved by multiple fixation points per fragment, or by use of the plate

and screw technique. For suspension wiring to be successful there must be

effective integrity of the upper jaw buttresses when this is not so suspension

wires and IMF will not prevent upward movement of jaw complex along an

arc centered at the TMJ leading to open bite anteriorly as well as posterior

gagging of occlusion.

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Except for circumzygomatic wire suspension, all craniofacial wire

suspensions require exposure of the suspension point on the front, on the

zygomatic frontal suture, on the infraorbital rim and on the piriform

aperture. A hole is drilled at the suspending point nd the wire inserted into it.

Both ends of the wire are now fixed in an awl which, with the wire loop, is

placed in the oral cavity for frontomalar suspension, suspension of the

glabella and infraorbital wiring. Circuimygomatic wiring requires only a

loop from the oral cavity circumfe ntial to the zygomatic arch and returning

into the oral cavity. Piriform aperture wiring is carried out by exposure of

the piriform aperture using a vestibulary incision. The wire ends, brought

into the oral cavity, are fixed laterally to the splint either in square tubes or

in small wire loops; however, they an also be conducted around the arch bar.

Tightening of the wire suspension is done after the occlusion has been

established and intermaxillary fixation applied. Suspension wires are

normally removed after 6 weeks using an intraoral approach, except or the

craniofacial suspension wire at the frontal bone. This must be removed by

exposure through a small incision on the wire loop transected here.

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52

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OPEN REDUCTION AND INTERNAL FIXATION BY

INTEROSSEOUS WIRING :

The limitations of internal fixation by wire suspension relate to incomplete

fixation of fracture fragments, closed reduction of the lower midface, and

compression as a mean of fixation. Closed reduction of ten does not

anatomically reconstruct the buttresses of the midface, and three

dimensional stability is not obtained. Midface shortening and retrusion

between the orbits and maxillary alveolus are common complications of

internal wire suspension. More accurate restoration of midface height and

projection can be achieved by open reduction in the lower maxilla (LeFort I

level). Anteriorly at this level the nasomaxiUary and zygomaticomaxillary

buttresses are stabilized with open reduction. Reconstruction of thin sinus

wall fragments between the two anterior pillars is omitted and the pterygoid

buttress is not operated upon. The posterior height of the midface is

restored by utilizing the ramus height of he mandible combined with

intermaxillary fixation.

Midface projection is restored in the Le Fort I level by open reduction of the

nasomaxillary and the 2ygomatico-maxillary buttresses. In the upper

midface open reduction of zygomatic and nasoethmoidal fractures is carried.

In edentulous patients intermaxillary fixation is omitted following open

reduction. Primary bon grafting replaces unusual or absent critical structural

supports.

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In associated fractures of the mandible it is important to reconstruct the

mandible both horizontally and vertically to provide a stable base for

intermaxillary fixation and prevent the mandible and maxilla drifting

posteriorly and superiorly, thereby producing a disk face. Stabilization of

ramus height by open reduction of subcondylar fractures prevents such

displacement. Midface fractures managed by extended open reduction

sometimes require 2-3 extra weeks of intermaxillary fixation.

OPEN REDUCTION AND INTERNAL FIXATION BY

MINIMICROPLATES AND SCREWS:

The classic treatment of midfacial fractures used to be intermaxillary

fixation combined with craniofacial wire suspension or open reduction and

external fixation by interosseous wiring, which is unpleasant for the patient

who is in many cases affected with multiple traumas.

Breathing is difficult, especially when the nose is tamponed and a nasal tube

is inserted for feeding. In some cases a tracheotomy is necessary and

feeding is only possible with liquids. Oral hygiene is limited, especially for

sedated patients in intensive care.

To prevent these disadvantages early and open surgical management of

midface fractures has become established, using miniplates, microplates and

screws. The procedure is based on exact repositioning of the minimum

possible number of fragments, and stabilization eventually in combination

with bone grafts. In addition to the advantages of exact fragment

repositioning, the maxillary height is stabilized and intermaxillary fixation is

no longer necessary.

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Maxime Champy in 1975 developed the technique used by Francois

Michelet in the early 1970s to describe a method of inserting monocortical

miniaturized plates on the mandible, and by Harle in 1975 and Luhr in 1979

on the midface. The technical advantages of miniplate osteosynthesis are the

use of small and easily adapted plates, monocortical application, functional

stability and biomechanical suitability. Indications for use of the miniplate

system have been found in orthognathic surgery, in craniofacial surgery, in

the treatment of midface fractures, in reconstructive bone surgery, and in

preprosthetic and dental implant surgery. The microplate system, a network

system using a number of different types and screws, h been developed in

different countries.

It is well known that today, except for mandibular reconstruction, mini and

microplates and screw osteosynthesis are the treatment of choice for

craniomaxillofacial bone surgery, but that there are significant differences in

design, materials, mechanical properties and cots between the commercially

available systems. For this reason they should not be considered

interchangeable. The surgeon must decide which system he prefers, and

selection should be based on the unit cost, the instruments and implants

available, their biocompatability and the compatibility of the implant.

SURGICAL APPROACHES TO EXPOSURE OF THE MAXILLA:

INTRAORAL APPROACH BY GINGIVOBUCCAL SULCUS

(SUBLABIAL) INCISION OR BY MARGINAL RIM INCISION :

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The typical intraoral incision lines for exposure of the maxilla are placed

within the unattached mucosa 4-5 mm beyond the level of the attached

gingiva. In order to reduce scar tissue formation and minimize the risk of

infection, the marginal rim incision can be used as an alternative. For the

edentulous patient the incision line or exposure of the maxilla is usually on

the crest of the alveolar ridge.

The lower half of the midface can be exposed using these approaches, as

well as the infraorbital rim and the lateral buttress of the maxilla. A common

complication of the vestibulary approach is wound dehiscence, which is

never seen after a marginal rim incision. The reason for this is the

immunological defense mechanism of the periodontium.

LOWER EYELID APPROACH:

The lower orbital rim and orbital floor can be exposed

transcutaneously through a subciliary, lower eyelid or infraorbital incision.

In the transconjunctival approach the incision is limited by the fornix. For

more extensive exposure a lateral canthotomy and cantolysis is necessary.

The lower eyelid incision shows the best results, with a lower complication

rate than the other approaches. The incision is placed parallel to the ciliary

margin just caudal to the tarsus. The orbicularis muscle is exposed and blunt

dissected in the direction of the muscle fibers. The skin muscle flap is turned

down and the orbital septum exposed as far as the infraorbital rim. After

this has been identified an incision is made from the facial side of the rim

above the infraorbital nerve through the periosteum. Using subperiosteal

dissection the orbital floor and the infraorbital rim are exposed above the

infraorbital nerve. After osteosynthesis the periosteum is approximated and

the skin closed without subcutaneous sutures.

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TRANSCONJUNCTIVAL LATERAL CANTHOTOMY APPROACH :

The transconjunctival lateral canthotomy approach provides wide exposure

to the orbital floor, lateral orbital wall, infraorbital rim and lateral orbital rim

upto approximately I cm above the frontozygomatic suture. This approach

is indicated in addressing fractures in these areas. The complication rate is

low ; however, blunting of the lateral canthus and entropion may occur.

These problems are eliminated during closure by approximating the cut edge

of the tarsal plate to the lateral canthus with a semipermanent suture. The

periorbital area is prepared in the usual fashion, with precautions to avoid

getting the preparation solution into the eye. A corneal shield may be used at

the surgeon's discretion.

UPPER LID BLEPHAROPLASTY APPROACH :

The upper lid blepharoplasty approach gives excellent access to the

frontozygomatic suture, with very good esthetic results, and is becoming

more and more popular. The incision is placed in an upper lid skin crease,

from midpupil to the lateral orbital rim. As usual in the orbital region

homeostasis is performed with bipolar cautery. Monopolar cautery can

damage the underlying sclera because of thermal conduction. The incision is

continued on the layer of the orbital septum towards the frontozygomatic

suture. The periosteum is incised and the fracture is exposed. After bone

surgery the periosteum is approximated and the skin incision closed by

running, intracutaneous or mattress sutures with no subcutaneous sutures.

BROW INCISION:

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The brow incision for exposure of the frontozygomatic suture is the most

common technique, and has an extremely low complication rate. An incision

is made through the skin parallel to the hair shafts the superior border of the

lateral brow overlying the frontozygomatic suture. The muscle fibers must

be blunt dissected down to the periosteum, which is cut and sharply

detached. After the application of osteosynthesis material the periosteum is

approximated subcutaneously and skin sutures placed. After surgery scars

are sometimes visible and localized hair loss can occur.

CORONAL APPROACH:

59

The coronal approach gives excellent exposure of the cranium and

upper craniofacial skeleton, but widening of the scar on the top of the head,

paraesthesias posterior to the incision and weakness of the temporal branch

of the facial nerve are documented complications. Shaving the head is not

necessary if dural exposure is not intended. The incision is made through the

scalp, the subcutaneous tissue and the galea until the loose layer of the scalp

between the galea and pericranium is reached. Hemostasis can be obtained

with cautery, scalp clips or running silk locking sutures. The dissection in

the layer over the pericranium down to the supraorbital rim is relatively

bloodless. Care must be taken below the fusion of the temporal lines because

of the temporal branch of the facial nerve, which passes over the zygomatic

arch 2 cm superior to the supra orbital rim. The pericranium is incised and

the dissection continued over the bone to the supraorbital rim. When the

neurovascular bundle of the frontal nerve is enclosed in a foramen the bone

bridge is excised. To preserve the temporal branch of the facial nerve, the

fusion of temporal line and of the superficial and deep layers of the deep

temporal fascia must be identified. If the dissection continues superficial to

the fascia, the frontal branch of the facial nerve will be transected. Inferior to

this line effusion a fit pad is seen which is exposed by an incision in the

superficial layer of the deep temporal fascia. The dissection continues

through the fat pad, leading to the zygomatic arch.

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After incision a subperiosteal detachment on the superior border of the

zygomatic arch is performed. The temporal branch of the facial nerve is now

retracted laterally with the periosteum of the arch and the superficial layer of

the deep temporal fascia. To prevent facial nerve injury sharp instruments

should never be used because penetration by a sharp instrument could cause

nerve damage. When the nerve has been protected the dissection can

proceed in the subperiosteal layer to the lateral orbital rim. If the medial wall

must be exposed the anterior and the posterior limbus of the medial canthal

ligaments and the lacrimal sac are identified. Caution must be taken to avoid

the anterior

ethmoidal artery. If dissection must proceed further the artery must be

clipped and divided to reduce the chance of an orbital hematoma.

If the canthal ligaments require reattachment they should be secured. Also,

the temporal fascia should be sutured for proper soft tissue configuration.

Wound closure is with either staples or sutures.

POST-OPERATIVE MANAGEMENT:

61

At the conclusion of the operative period a nasopharyngeal airway is

inserted and it is kept patent by occasional aspiration with a length of 3 mm

bore polythene tubing attached to a sucker nozzle. If craniomaxillary

fixation has been employed, it is possible to defer IMF until the patient has

fully recovered consciousness to enable him to breath through the mouth. If

IMF a tongue suture brought out of the mouth through the fixation to enable

the tongue to be controlled while the patient is unconscious. Suction

apparatus, oxygen, tracheostomy set, wire cutters should be available along

with emergency drugs by the bed side in case an emergency should occur.

Nasopharyngeal airways should be kept in position until the patient should

be fully conscious and has an adequate airway and maintains vital signs. If

patient is cerebrally irritated and restless, IV diazepam is one suitable

sedative which may be administered. When patient is conscious and

following removal of nasopharyngeal airway respiration may be helped by

occasional suction and clearing of blood and mucous from the teeth and

coating the lips with petroleum jelly. Prophylactic antibiotics for the first

week should be mandatory. Adequate fluids by mouth are required. Vital

signs to be recorded and maintenance of oral hygiene. In cases necessary a

nasogastric tube should be placed. In later post-operative period early

ambulation of the patient is desirable and until this is possible the patient

should have regular breathing and leg exercises. Fractured are untied in 3 to

4 weeks and fixation can be removed at this time.

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COMPLICATIONS

– Failure to restore anatomic contour leads to septal deviation

– Malocclusion

– Infraorbital nerve paresthesia

– Enophthalmos

– Infected hardware

– Altered vision

– Sinusitis

– Anosmia

– Non-union

– Csf leak

CONCLUSION:

• Midface fractures occur in a wide variety of patterns

• The various extended access approaches can be tailored to these

fracture patterns

• Restoration of the facial buttresses is crucial in reestablishing the

pretruamatic aesthetic structure and function of the facial skeleton

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REFERENCES:

Maxillofacial Injuries - Rowe and Williams.

Oral and Maxillofacial Trauma - Raymond J.Fonseca.

Maxillofacial Surgery - Peter Ward Booth.

Killey's fracture of middle third of facial skeleton.

Maxillofacial trauma by Robert H.Mathog.

Pediatric Maxillofacial Surgery- Kaban

Management Of Midfacial Fractures – Joms (1993)51;960-968

www.sciencedierct.com

www.google.com

emedicine.com

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