Bones of the Skull. Frontal bone Supraorbital foramen Plate 2A Frontal bone.
Cummings Chap 23 Maxillofacial Trauma 10/31/12. Anatomy/Physiology Upper 1/3 Frontal bones-...
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Transcript of Cummings Chap 23 Maxillofacial Trauma 10/31/12. Anatomy/Physiology Upper 1/3 Frontal bones-...
Anatomy/PhysiologyUpper 1/3• Frontal bones- “relates” to FS, brain, orbits,
cribiform, supratrochlear/supraorbital nMiddle 1/3• Zygoma- facial projection, masseter insertion,
inferolateral orbital rims/walls• Orbits- 7 bones (frontal, zygomatic, max,
lacrimal, ethmoid, sphenoid, palatine).• maxilla- V2, infraorbital rims/floors, NLD, teeth,
MCL• nose- breathing/olfaction, cosmesis– Most freq fx bone in human body
Anatomy/Physiology
Lower 1/3• Mandible – Dentition/occlusion– Horseshoe shape + TMJ absorbs force from transmitting to
MCF– 32 teeth, 8/quadrant– Angel Classification of occlusion
• Class I mesiobuccal cusp of max 1st molar sits in buccal groove of the mandib 1st molar.
• Class II max molar more anterior/chin retruded- overbite• Class III max molar more posterior/chin prognathic- underbite
Eval/DiagnosisPE• ABCD, gen appearance, CNs, Blood/CSF, FBUpper 1/3• Test motor, sensation, step offsMid 1/3• Eval globe/orbits, visual acuity, EOMs,
proptosis/enopthalmos, ophthal consult• Nasal bone- fx, septal hematoma, NOE• NOE fx- Intercanthal distance- normal 30mm, ½
interpupillary distace, >45mm=telecanthus, loss of nasal dorsal height, epicanthal folds, MCL traction test
Lower 1/3• Open mucosal teas, V3 sensation, occlusion, mouth
opening/trismus.
Radiographic Eval
Axial cuts- good to eval FS, zygomatic arch, vertical orbital walls, vertical structures
Coronal cuts- good to eval orbital roof/floor, pterygoid plates, horizontal structures
CT face w/ fine cuts 1.5mm
SchemasUpper 1/3• FS fx –
– Ant table- cosmesis, sinus function– post table- sinus fxn, neurosurg
• Supraorbital rim comminuted fx FS recess injury• Centrally located + severe fx CSF leakMid 1/3Orbits
– Orbital apex syndrome- II, III, IV, V, VI– Superior orbital fissure syndrome- III, IV, V, VI– Blowout fx- rims intact w/ 1 or more walls fx, usu floor/medial
wallLe ForteNOE
Schemas
Le Forte ?- complete craniofacial separation- zygoma, through orbit, nasaofrontal jxn
Le Forte ?- horizontal max fx above dentition
Le Forte ?- pyramidal fx- orbital rims/floor, nasal root
Schemas
Le Forte I- horizontal max fx above dentition
Le Forte lI- pyramidal fx- orbital rims/floor, nasal root
Le Forte III- complete craniofacial separation- zygoma, through orbit, nasaofrontal jxn
Schemas• Type ? bone fragment
containing MCL freed from surrounding bone
• Type ? MCL tendon detached or attached to a fragment that is irreparable ie bilat orbital wall fx
• Type ? comminuted fx, repairable via transnasal fixation
Schemas• Type I bone fragment
containing MCL freed from surrounding bone
• Type II comminuted fx, repairable via transnasal fixation
• Type III MCL tendon detached or attached to a fragment that is irreparable ie bilat orbital wall fx
Management- access• Start ppx abx immedSurgical access- existing lac? Upper 1/3• Coronal incision, access to pericranial flap, beware frontal br and
supraorbital nMid 1/3• Zygoma- gilles, gingivobuccal• Lateral orbital rim- upper bleph, lateral brow, lower lid
transconjunctival +/- lateral canthotomy• Orbital floor- transconj pre v post septal, transcutaneous subciliary v
lower lid crease (frost stitch)• Medial orbit- transcaruncular, lynchLower 1/3• Mandible- intraoral, beware mental n, transcervical-
submand/submental incision, retromandib inci, beware mental n, facial n.
Biomechanics
Facial skeleton has areas of strength and weakness
Strength- buttresses/pillarsWeakness- crumple zones eg. LP/ethmoid
bones- direct blunt trauma to central face telescoping NOE fx, dissipates force protecting globes. Same concept for purpose of sinuses.
BiomechanicsUpper 1/3• frontal ant table- weak• supraorbital rim- strong, protects orbits and ant
cranial fossaMid 1/3• vertical buttress x4: nasofrontal/nasomax,
frontozygomatic/zygomaticomax, pterygoid• horizontal bars x4: frontal bar, zygoma, infraorbital
rim, palateLow 1/3• Mandible upper beam- tension forces• Lower beam- compressive forces
Fracture Repair- principlesPurpose of fx repair- regain aesthetic form and occlusal fxnRigid fix- elim movement across fx, allows primary bone
healing, minimizes callus formationOcclusion>>fracture reductionMMF, ivy loops, IMF- to re-est occlusionWork from stable to unstable, known to unknown, periphery
to centerRe-est facial height 1st -repair mandible 1st, make sure midface
not impacted/rotated before rigid fixationThen stabilize buttresses- L/J plates Then central face Then orbits- floor has irregular convexity, not a complete
sphere, failure to recognize will cause enopthalmos Repair CSF leaks immediately, longer leak incr r/o
meningits
Mandible fx repair2 schools
1) Champy- miniplates + monocortical screws2) Speisl- MMF + compressive plate w/ bicortical screws
Body- single miniplate +/- bicortical compression plateSymphysis- 2 miniplatesAngle- very complex/changing forces, recon plate v single 1.3mm miniplate v
2 2mm miniplates, highest rate complicationsRamus- 2 2mm miniplatesSubchondylar- MMF v open- risk to FN
indications for open- – chondylar displacement into MCF – inability to obtain reduction– lateral extracapsular displacement of chondyle– FB
Relative indications- – B chondylar fx + edentulous, + comminuted midface fx, +gnathologic problems– when splinting not recommended
Mandible fx repairLoad sharing- depends on integrity of bone, eg miniplate,
compression plate, lag screwLoad bearing- atrophic/thin/comminuted fx- repair needs to
bear load across the affect bone eg recon plate w/ 4 bicortical screws on each side. Fall-back technique for all repairs
Locking (v nonlocking) screws allows for less than perfect plate bending.
Other options:• ex fix, MMF 4-6 wks
Tooth in fx line-leave alone if: healthy, 3rd molar in angle fxremove if: infected, interferes w/ reduction
Frontal Sinus Fx
Anterior wall nondisplaced- obsAnterior wall displaced- repairAnterior wall + FSR injury- oblit v obsPosterior wall nondispl +/- FSR- obsPosterior wall displ- trephine + transcut endoscopy
(r/o herniated brain)
Obliteration- pack w/ fat, seal recess w/ cement or pericranial flap
Cranilization- removal of posterior table
NOE repair
Type I- stabilize the floating bone to surrounding bone w/ plate
Type II/III- stabilize MCL to the contralat frontal bone or MCL w/ permanent suture or wire