Maxillofacial Trauma Flashcards
What GCS score would necessitate intubation?
GCS 8
What are the stages of hemorrhagic shock?
-Stage I: 750 mL blood loss, slightly anxious
-Stage 2: 750-1500 mL blood loss, anxious, slightly tachycardic
-Stage 3: 1500-2000 mL blood loss, confused, tachycardic, hypotensive, 5-15 mL urine output
-Stage 4: 2000 mL+ bloss loss, lethargic, hypotensive, scarce urine output
Describe the Glasgow Coma Scale
-Eyes 1-4: No response, pain only, verbal stimuli, spontaneous
-Verbal 1-5: No response, incomprrehensible, inappropriate, confused, oriented
-Motor 1-6: No response, extension, flexion, withdraws from pain, purposeful, obeys command
How are head injuries classified?
-Severe: GCS 8 or less
-Moderate: GCS 9-12
-Mild: GCS 13-15
-T indicates intubated patient
What are the zones of the neck for penetrating trauma?
-Zone 1: Thoracic inlet to cricoid cartilage
-Zone 2: Cricoid cartilage to angle of mandible
-Zone 3: Angle of mandible to the base of skull
What is the definition of rigid fixation and semi-rigid fixation?
-Rigid fixation: Fixation that prevents interfragmentary movement when a load is applied
-Semi-rigid fixation: Fixation that is not sufficient strength to prevent interfragmentary movement during loading but is adequate to allow union of bone
What is the difference between load bearing and load sharing?
-Load Bearing: Hardware is sufficient strength to bear the entire load. Need at least 3 screws at each segment
-Load sharing: Hardware does not bear entire load but shares with surrounding bone. Use of miniplates and monocortical screws
What are the ideal lines of osteosynthesis?
-Described by Champy
-Line around mandible where plating the tension and compression forces are balanced, offers the best biomechanical advantage for positioning plates/screws
What is the difference between locking and non-locking plates/screws?
-Non-locking: Plate must be adapted intimately to the bone. Compression of the plate onto the bone may cause bone resorption
-Locking: Screw locks in to the plate while being tightened. Does not require perfect adaptation
Describe primary vs secondary bone healing.
-Primary bone healing: Heals by haversian remodeling directly across fracture site. No gap between segments. If gap, deposition of lamellar bone if small gap exists. Requires absolute rigid fixation with minimal gap
-Secondary bone healing: Bony callus forms across fracture site to aid in stability and immobilization. Occurs when there is mobility. Secondary bone healing involves formation of granulation tissue and then thin layer of membranous ossification. Hyaline cartilage is deposited and replaced by woven bone and matures to lamellar bone
What are important aspects of the HPI in a trauma patient?
-Mechanism of injury
-LOC
-Confirm ATLS/PALS
-Ensure proper consultations
-Ensure C-spine evaluated
What is battle’s sign indicative of?
-Base of skull fracture
Describe the nomenclature in mandibular trauma: simple, compound, comminuted, greenstick, pathologic.
-Simple: Not open to external environment
-Compound: Open to external environment
-Comminuted: Splintered/crushed
-Greenstick: Only one cortex fractured
-Pathologic: Pre-existing disease of bone leads to fracture
Describe vertically/horizontal favorable.
-Vertically favorable: Medial pull of muscle reduces fracture
-Horizontally favorable: Vertical pull of muscle reduces fracture
For an edentulous mandible, where is the blood supply mostly from?
-Dependent on periosteal blood flow
-Decreased inferior alveolar artery blood flow
What are the classifications of mandibular condyle fractures?
Wassmud Scheme
-I: Minimal displacement of head
-II: Fracture with tearing of medial joint capsule, bone still contacting
-III: Bone fragments not contacting, condylar head outside capsule medially and anteriorly displaced
-IV: Head is anterior to the articular eminence
-V: Vertical or oblique fracture through condylar head
AO Classification: Use sigmoid notch, lateral pole of condyle, high vs low condylar neck
What are the goals of condylar fracture repair?
-Pain free opening over 40 mm
-Good excursive ROM
-Preinjury occlusion
-Stable TMJ
-Facial/jaw symmetry
What are the criteria for absolute and relative indications of condylar repair?
Zide Absolute:
-Middle cranial fossa involvement
-Inability to achieve occlusion with CR
-Invasion of joint space by a foreign body
-Lateral capsule violation and displacement
Zide Relative:
-Bilateral condylar where vertical height needs to be restored
-Associated injuries requiring early or immediate function
-Medical conditions that indicate open
-Delayed treatment with misalignment of segments
What is a non-union (including time-frame)?
-Arrested healing after appropriate time has passed
-Mobility after 4 weeks without treatment or 8 weeks with surgical management
How is bleeding during Lefort fracture managed?
-If from pterygoid muscles: Pack with surgicel/fibrin
-If from pterygoid plexus: Tread with LA packing
-If from descending palatine, PSA, or sphenopalatine treat with vessel clips
-Consider embolization if bleeding can’t be controlled with above measures
What are the classifications of Lefort fracutres?
Lefort I: Horizontal (above root apicies)
Lefort II: Pyramidal (extends to nasofrontal region, inferior orbit)
Lefort II: Complete craniofacial disjunction (zygomaticofrontal suture, orbital lateral walls)
What are the classifications of ZMC fractures?
Knight and North
-Group 1: Nondisplaced
-Group 2: Arch fractures
-Group 3: Unrotated
-Group 4: Medially rotated
-Group 5: Lateral rotation outward
-Group 6: Complex fracture
Zingg
-Type A1: Isolated arch, A2: Isolated lateral wall, A3: Isolated inferior orbital rim
-Type B: Monogragment of all 4 buttresses
-Type C: Comminution of zygomatic bone
How can you confirm intra-op reduction of the zygomatic arch?
-Submentovertex view radiograph
What is the sequencing of fixation for a ZMC fracture?
-ZF (restore facial height)
-ZM (Facial projection)
-Fixate orbital rim
-Orbital floor last
ZS good indicator of 3D position of zygoma
How is a post-op asymmetry/malunion treated s/p ZMC reduction?
-Can be managed with osteotomies, onlay graft, alloplastic implants
What is the average volume of the globe?
-30 mL
What bones make up the orbit?
-Roof: Frontal/lesser wing of sphenoid
-Lateral: Greater wing of sphenoid, zygoma
-Floor: Maxilla, zygoma, palatine
-Medial: maxilla, ethmoid, lacrimal and sphenoid
Where is the infraorbital groove?
2.5-3 cm posterior to the orbital rim (infraorbital nerve runs through and exits 5 mm below the infraorbital rim)
What structures are in the superior orbital fissure?
-CN III, IV, V1, VI, sympathetic fibers
-Superior opthalmic vein
-Recurrent/middle meningial artery
What structures are in the inferior orbital fissure?
-V2, parasmpathetic branch of pterygopalatine ganglion
-Inferior opthalmic vein
What structures are in the optic canal?
-Optic nerve, opthalmic artery, sympathetic fibers
Where is Whitnall’s tubercle and what attaches to it?
-10 mm below ZF suture, 3-4 mm insite lateral orbital rim
-Lateral horn of levator aponeurosis, lateral canthal tendon, lockwood’s ligament, check ligaments (all these are lateral retinaculum)
What is the annulus of Zinn?
-Tendonous ring of fibrous tissue at apex of the orbit surrounding the nerve that is the origin of the rectus muscles of eye
What are the safe distances of the orbit?
-From intact anterior lacrimal crest:
-Anterior ethmoid foramen 24 mm
-Posterior ethmoid foramen 36 mm
-Optic foramen 42 mm
What are the layers of the eyelid?
-Skin
-Subcutaneous tissue
-Orbicularis oculi
-Septum
-Tarsal plate
-Conjunctiva
What is the orbital septum?
-Dense CT arising from orbital periosteum; forms anterior boundry of the orbit
-1-2 mm below infraorbital rim it fuses with thickened periosteum to form arcus marginalis
What are normal tonometry values?
10-20 mmHg
Where does the nasolacrimal duct open?
-10 mm behind nasal aperture (into inferior meatus), Hasner’s valve
What is a white eyed blowoutfracture?
-Intact orbital rim but blow-out orbital floor fracture. Typically in pediatric population with restrictive strabismus
What are the indications for orbital repair?
-Larger fractures: 50% orbital floor, enophthalmos 2 mm, diplopia in primary gaze
-Muscle incarceration is a true emergency
What is the technique for a tranconjunctival orbital repair?
-Corneal shield
-Local
-15 blade for incision through lateral canthus (tip of iris scissor placed insite palpebral fissure, extending laterally to the depth of the underlying lateral orbital rim. Scissors used to cut horizontally through the lateral palpebral fissure (skin, orbicularis muscle, orbital septum, lateral canthal tendon and conjunctiva
-Using lateral orbital rim as a stop, inferior cantholysis is performed by turning the orientation of scissors vertically to incise inferior canthal ligament
-Using blunt tipped pointed scissors, dissection through the conjunctiva, stay 3 mm away from caruncle
-Use scissors to incise conjunctiva below curvature of the tarsal plate (may use 5/0 nylon traction sutures)
-Palpate bony orbit, blunt dissection to orbital rim
-Periosteal elevator to dissect and visaulize floor. Use broad maleable to protect orbit
-Reconstruct with medpore titan
-Foreced duction
-4/0 vicryl to reattach lower limb of lateral canthus
-6/0 skin suture along horizontal lateral canthotomy
-6/0 fast gut for conjunctiva
How is an orbital implant infection managed s/p ORIF orbital floor?
-Implant removal, culture, start antibiotics
How is post-op implant migration managed s/p ORIF orbital floor?
-Early: Reposition with additional fixation
-Late: Implant removal
How is post-op ectropion or entropion managed s/p ORIF orbital floor?
-Ectropion: Shortening of anterior lamellae. May require tarsal strip
-Entropion: Due to shortening of the posterior lamellae. May require suturing (passing a gut suture through the inferior fornix anteriorly towards to lashes). May require grafting (oral mucosa, contralateral eyelid, ear)
What is sympathetic ophthalmia and how is it treated?
-Injury induced autoantibodies to uveal tissue, 80% occur within 3 months
-Enucleation: Removal of globe without rupture
-Evisceration: Leave the sclera/cornea
-Exenteration: Remove entire contents of the orbit
How is a post-op retrobulbar hemorrhage treated s/p ORIF orbital floor?
-1% incedence
-Pain, proptosis, decreased visual acuity
-Manage medically with IV infusion of mannitol 2g/kg to shrink vitreous humor, possibly acetazolamide or steroids
-Manage surgically with lateral canthotomy with cantholysis
How is a nasolacrimal duct injury tested for?
-Jones I: Few drops of fluorescene or propoful in lower conjunctival sac, observe if drains in nose. If not go to Jones II
-Jones II: Irrigate the punctum and inject into puncta/canaliculi. If drainage seen then issue with lacrimal sac. If nothing seen then injury more distal
Describe primary and secondary repair of the nasolacrimal duct.
-Primary repair: Dilate with bowman probe, place stent (crawfor tube or jackson tube) through puncta and duct. Suture both ends with 8/0 PDS and leave for 3 months
-Secondary repair: Dacryocystorhinostomy. Create a bony window between the lacrimal sac and nose
How is a corneal abrasion treated?
-Pain, tearing, photophobia, foreign body sensation
-Treat with topical antibiotics
What is hyphema (including grading)?
-Bleeding from a torn vessel at the root of the iris in the anterior chamber. Blurred vision and photophobia
-Grade 1: 1/4 of anterior chamber
-Grade 2: 1/2 of anterior chamber
-Grade 3: 3/4 of anterior chamber
-Grade 4: Complete blockage (blackball)