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Head and Neck / CF > Mandible Fractures > Flashcards

Mandible Fractures Flashcards

1
Q

What are the elevators of the mandible?

A

Temporalis
Medial Pterygoids
Lateral Pterygoids
Masseter

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2
Q

What are the depressors of the mandible?

A 
Supra hyoid group of muscles:
Stylohyoid
Mylohyoid
Geniohyoid
Digastric
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3
Q

What are the origin, insertion, function and innervation of temporalis?

A

O: temporal fossa
I: Coronoid, Anterior surface of rams
F: elevator
N: V3 mandibular branch

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4
Q

What are the origins, insertions and innervation of medial Pterygoid?

A

O: medial aspect of lateral pterygoid plate
I: lingual aspect of angle and ramus
Fx: powerful elevator, synergistic w masseter
N: V3 medial pterygoid br.

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5
Q

What are the origin, insertion, function and innervation of Masseter?

A

O: Z arch (superficial head ant 1/2, deep head post 2/3)
I: buccal aspect of body and rams
Fx: powerful elevator, synergistic with medial pterygoid
N: V3

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6
Q

What are the origin, insertion, function and innervation of lateral pterygoid?

A

O: Lateral aspect of lateral pterygoid plate
I: TMJ joint capsule
Fx: Protrusion, translation, side to side motion
N: V3 lateral pterygoid br.

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7
Q

What are the origin, insertion, function and innervation of mylohoid?

A

O: mylohoid line along mandible
I: hyoid
Fx: elevates hyoid
N: ION (mylohyoid br)

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8
Q

What are the origin, insertion, function and innervation of geniohyoid?

A

O: inferior mental line
I: Hyoid
Fx: elevate tongue
N: hypoglossus (CN12)

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9
Q

What are the origin, insertion, function and innervation of stylohyoid?

A

O: styloid
I: Hyoid
Fx: displaces hyoid posteriorly
N: Facial (CN7)

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10
Q

What are the origin, insertion, function and innervation of digastric?

A

O: Mastoid process (post belly), Digastric fossa of mandible (anterior belly)
I: hyoid intermediate tendon
F: hyoid elevation
N: Ant belly, V3, Post belly CN7

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11
Q

Describe the functions and course of the Inferior Alveolar nerve

A

Sensory Branch of V3 to lower teeth, lower lip, chin, vestibular gingiva
Motor branch to mylohyoid
Enters mandibular ION canal at lingual cortex, inferior to molar root and exits at mental foramen, located inferior to 2nd premolar

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12
Q

Describe your landmarks for the marginal mandibular nerve

A

80%: lies posterior to facial artery, at the level of the inferior mandibular border. Anterior to master, approx. 3cm from angle
20%: lies anterior to facial artery and will 100% be above mandible border.
It is never >1,5cm below the mandible border

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13
Q

How do you classify mandible fractures?

A

By:
1- Location
2- Open vs closed
3- Displacement
4- Dentition (class 1 - teeth both sides, class 2- teeth on one side, class 3 - no teeth on either side)
5- Favourability
6- isolated / segmental / comminuted (JP added this)

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14
Q

What is the blood supply to the mandible

A

Inferior alveolar artery (travels with IAN in mandibular canal)
Muscle attachments

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15
Q

What mandible fractures are favourable?

A

Ramus

Some angle

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16
Q

What mandible fractures are unfavourable?

A

Parasymphyseal/symphysis
Some angle
High condylar (medially displaced by lateral pterygoid)

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17
Q

What physical finding do you anticipate with a condylar fracture?

A

Contralateral open posterior bite and translation to ipsilateral side with mouth opening

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18
Q

What physical finding do you anticipate with a bilateral candela fracture?

A

Anterior open bite

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19
Q

What specific imaging do you order for mandible fracture assessment? (3 answers)

A

1- Panorex (PA, lateral, RLO, LLO, Townes, submentovertex)
2- Panorex - 80% sensitive
3- CT (2.5mm cuts) - 100% sensitive

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20
Q

What is non-operative management for a mandible F#

A

Soft diet

Close follow-up (weekly)

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21
Q

What type of mandible fracture can be considered for non-operative management?

A
  • minimal displacement
  • no malocclusion
  • normal ROM (no translation)
  • patient : elderly, paediatric w greenstick/incomplete
  • Location: condyle, ramus favorable, coronoid
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22
Q

What is centric occlusion?

A

Occlusion with maximal intercuspation of teeth

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23
Q

What is centric relation?

A

Occlusion with condyle seeded in glenoid fossa (in the most posterosuperior position)

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24
Q

What are methods of fixation for operative management of a mandible f#

A 
1- splints
2- Circumdental wiring and arch bars
3- MMF
4- Rigid internal fixation (Rigid stability AO/ASIF)
5- Non-rigid Fixation (champy)
6- External fixation
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25
Q

Indications for ORIF of mandible F#

A

Mandible F#, malocclusion AND you are
Desire to avoid MMF/uncooperative/head injured

1- Unable to hold fixation with teeth

  • Class 2 or Class 3 (or edentulous)
  • Edentulous mandible* OA/JF

2- Unable to obtain anatomic reduction

  • Comminuted
  • Bone Loss, Bone Discontinuity * OA/JF
  • Osteomyelitis

3- Unable to maintain reduction with a closed approach

  • Favorable or unfavourable Class 1 where stability is desired
  • Combination of Maxillary and mandibular F#
  • Displaced or likely to rotate ***
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26
Q

What is functional stability versus rigid stability in mandible fracture fixation

A

Rigid stability - stability achieved w fixation plates that allow no movement across F# site
Functional stability - movement possible across f# gap but balanced by external forces within limits of what allow f# to heal
Load sharing: functional stability achieved w plate in conjunction with stabilizing forces by anatomic abutment of non-communized fracture segments
Load bearing - functional stability achieved by fixation system only

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27
Q

What are contraindications to MMF?

A

1- seizure disorder
2- Neurologic/psych disorder
3- Pulmonary compromise
4- Eating disorder

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28
Q

What are indications for Closed reduction and MMF ?

A 
1- non displaced F#
2- grossly communited F#
3- edentulous patients (using splint)
4- Pediatric F# (at mixed dentition)
5- Isolated condylar Fracture
6- Coronoid fracture
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29
Q

Indications//situations for External fixator for mandible f#

A

OLD school answers below (in reality today, OA/JF, no use for ex fix, just tx infected bone with locking recon plate)

  • Pathologic F#
  • Traumatic bone loss
  • Lack of soft tissue coverage
  • Infected/contaminated wound/OM
  • to maintain spatial relationships for cancer resection
  • edentulous mandible if atrophic mandible but sufficient to hold two screws
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30
Q

What are advantages of internal fixation with plating

A
  • avoid MMF
  • ## rigid internal fixation (reliable fracture healing)
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31
Q

What are the disadvantages of plating?

A
  • risk of injury to IAN, mental n, mar mandibular n
  • risk of injury to tooth roots/buds
  • periosteal stripping (blood supply)
  • stress shielding (force transmitted to plate)
  • risk of OM
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32
Q

What are indications for internal fixation with plating for mandible f#

A
  • class 2 and class 3 fractures
  • displaced f#
  • condylar f# dislocation >12yo
  • condylar # dislocation and another fracture
  • MMF contraindicated
  • edentulous patient
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33
Q

What are contraindications to internal fixation with plating?

A
  • osteomyelitis
  • metabolic bone disorder (renal osteodystophy, hyperparathyroidism)
  • medically unfit for surgery
34
Q

What are indications for Closed reduction

A
  • medically unfit patient, unable to undergo fixation or open reduction
  • condylar fractures
35
Q

What is the role of compression plating in mandible fractures?

A
  • to increase fracture compression and contact
36
Q

What other methods of fixation must you use in combination with compression for mandible f#?

A

Tension band or arch bars to prevent lingual cortex distraction

37
Q

What is the role of locking plate?

A

More forgiving if plate not bent perfectly

Acts as internal exfix

38
Q

What is the theory of nonrigid fixation (champy/load sharing/functional stability)

A
  • Only tensile forces are terrible

- Miniplates (monocortical) can be placed along lines of osteosynthesis

39
Q

Where do you place miniplates for non rigid fixation?

A

1- Posterior to first PREmolar, miniplates are effective in the midbody position
2- Anterior to first PREmolar, two plates are used 4-5mm apart

40
Q

When is nonrigid fixation not possible as a management strategy?

A

comminution

Bone loss

41
Q

What is the theory of rigid fixation?

A

no micromovement at fracture site allows for 1’ bone healing

42
Q

What are the AO principles?

A
  • anatomic reduction
  • functionally stable fixation
  • atramatic operative technique
  • ealy active pain free mobility
43
Q

What are options for fixation according to Ao principle

A

1- Tension band (miniplate) + larger bicortical inferior plate (>=2.3mm) to neutralize compression and torsion forces
2- Large recon plate (2.3-3-0mm) to neutralize tensile, compressive,torsional forces

44
Q

Describe the transoral approach (LBS)

A

1- incise through mucoa w 1cm cuff

2- avoid injury to mental nerve (anterior to 2nd PREmolar)

45
Q

Describe transbuccal approach

A

external incision for trocar placement

46
Q

Describe submental approach

A

external scar to expose and visualize the lingual cortex

47
Q

Describe landmarks and position of structres to avoid in a submandibular approach (Risdon)

A
  • 2cm below inferior border of mandible (to avoid marg mand br - located at border or up to 1.5cm below, lying over facial vessels)
  • identify entire plane of platysma, dissect under and carefully cut through platysma to reveal deep cervical fascia
  • facial vessels run anterior to masseter border
  • the premasseteric notch identifies where the CN7 branch may be inferior to border
48
Q

Describe retromandibular approach

A
  • below earlob at posterior border of ramu, incision through skin subcut, then incise through platysma protecting potnetial facial n br below
  • incise though perygomasseteric sling
  • release masseter sling
49
Q

Specific f#: Alveolar f#

A

arch bar, tooth splint, circumdental wires, dentures wired to jaw

50
Q

Indications for tooth extraction

A
  • Root apex exposed or fractured
  • teeth preventing reduction
  • grossly mobile teeth with evidence of periapical injury or disease
51
Q

Management specific F#: symphysis

A

CR and Fixation with MMF if stable - rare
Usually ORIF b/c unstable or assocaited w condylar F#
ORIF with compression/lag screws
ORIF w compression plate at inferior border + tension or arch bar
ORIF with two miniplates

52
Q

Management specific F#: body

A

CR and fixation - MMF - rare!!
Usually ORIF
ORIF w compression or non compression plate inferior border + arch bar or tension band or two miniplates

53
Q

Management specific F#: angle F#

A

CR and fixation with MMF is associated fractures (condyle/midface)
USually ORIF with tooth etraction of 3rdmolar if diseased or preventing reduction
Traditional AO - compression plate at inferior border, 2 bicortical screws per side + tension band/arch bar superiorly
Miniplate- single 2.0mm miniplate on external oblique line -

54
Q

Management specific F#- ramus F#

A

Undisplaced, maintianed V height w molars in place and reliable - soft diet 6wks and close observ
Undisplaced, missing molars so no V height maintenance, MMF 4-6 wks w elastics
Displaced, attempt CR and MMF
If failed CR, ORIF w two miniplate and retomandibular approach

55
Q

Management of condylar f#

A

Non- surgical (soft diet 6wks):

  • high neck or head (intracapsular) w no dislocation/malocclusion
  • condylar neck
56
Q

What are absolute and relative indications for ORIF of a condylar F#?

A

Absolute

  • displacement into middle fossa
  • foreign body within joint
  • lateral extracapsular dislocation of condylar head
  • inability to get adequate occlusion with closed methods

Relative

  • bilat subcondular F#, disaplced + midface
  • subcondylar f# with panface that needs re-established V height
  • shorted ascending ramus
57
Q

Classificaiton of edentulous mandible

A

according to amount of bone in the body of mandible
Mild atrophy - >20mm
moderate atrophy 10-20mm
Severe atrophy

58
Q

Management minimally displaced edentulous mandible

A
  • stable - conservative management

- unstable - MMF w circummandibular wire

59
Q

Management displaced/comminuted edetulous manidble

A
  • external approach
  • recon plate (load bearing)
  • minimal periosteal stripping
  • primary bone grafting
60
Q

PEdiatric fracture - indication for nonsurgical amangemetn

A
  • high neck/head (intracapsular) condylar f#
  • coronoid f#
  • BODY,angle F# with minimal displacement
61
Q

Pediatric fracture - options for fixation

A
  • interdental wiring (minimally displaced) - NOT if
62
Q

Describe ORIF principles in pediatric mandible fractures

A
  • minimal periosteal stripping
  • 1 miniplate 1-1.5mm inferior border only with monocortical screw
  • resorbable plate if
63
Q

What are complications of mandible fractures?

A
  • malocclusion
  • delayed union, non-union
  • infection
  • exposed hardware
64
Q

What are cuases of malocclusion following mandible f# treatment

A
  • failure to get centric relation b/c mandible is forced into occlusion wihtout seeding condyles
  • failure to get centric occlusion w MMF before ORIF
  • other f# missed
  • arch bar prior to exposure may shorten mandible segments
  • compression causing distraction of superior lingual cortex
  • poor plate contouring
65
Q

What is treatment of malocclusion

A
  • elastics if arch bar in place
  • orthodontics
  • repeat OR
66
Q

What is definiton of delayed union?

A
  • not clinically stable by 6wks
67
Q

Wha is definition of non-union

A

not clinically stable at 10wks

68
Q

Causes of non-union/delayed union

A
  • unstable fixation
  • early MMF release
  • hardware failure
  • infection
  • damaged teeth
69
Q

Treatemnt of non-union/delayed union

A

If unstable, ORIF w rigid fixation, graft if gap after reduction >2cm

70
Q

Causes o finfection

A

DIrectly realted to stability - RIGID fixation decreases fixation

71
Q

Treatment of infection

A 
aspirate for culture
antibiotics
debridement of necrotic sequestrae
rigid fixation +/- BG if gap
drainge of collection
72
Q

Causes of exposed hardware

A

minor exposure no infection - leave until f# heals then remove
major exposure or infection - remove hardware and achieve rigid fixation.

73
Q

What defines an angle fracture?

A

1st molar to angle

74
Q

What defines a body fracture?

A

1st premolar to 1st molar

75
Q

What defines a symphysis fracture?

A

between the canines

76
Q

What defines a ramus fracture?

A

below sigmoid notch

77
Q

What forces act on the mandible fracture?

A

tensile forces along alveolar ridge

compression and torsion forces along inferior border

78
Q

What are landmarks for ION block?

A

5 mm below orbital rim, in line with medial limbus. If injecting intraoral, aim toward lateral canthus

79
Q

What are landmarks for greater palatine block?

A

midway between midline and teeth, in line with 2nd molar

80
Q

What are landmarks for Nasopalatine block?

A

midline, 5mm behind incisors

81
Q

What are landmarks for Inferior Alveolar Nerve block?

A

1cm above occlusal plane and 1cm posterior to medial ramus

82
Q

What muscle does IAN innervate?

A

mylohyoid

Head and Neck / CF (27 decks)

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