Trauma zygomaticomaxillary complex (ZMC) and orbital fractures Flashcards
A ZMC (“tripod”) fracture involves which structures?
Tripod fracture is a misnomer because a ZMC fracture
involves four sites (tetrapod fracture is a more accurate
description):
● Temporal bone (zygomaticotemporal suture)
● Maxilla (zygomaticomaxillary suture)
● Frontal bone (zygomaticofrontal suture)
● Sphenoid bone (zygomaticosphenoid suture)
In ZMC fractures, what usually causes restricted
mandibular opening?
Impingement of the zygomatic arch on the coronoid process and temporalis muscle
List surgical complications associated with ZMC
fracture repair.
Lid malposition (ectropion, entropion), persistent diplopia, facial and malar asymmetry, plate palpability, malunion/ nonunion, enophthalmos, cheek numbness (V2), and blindness (extremely rare)
What approaches are the most appropriate for an isolated zygomatic arch fracture with no comminution?
Gilles approach or Keen approach
What is the most prominent portion of the ZMC, and where is it located?
Malar eminence located 2 cm inferior to the lateral canthus
Describe the Zingg classification of ZMC fractures.
● Type A: Isolated to one segment of the ZMC
○ A1: Zygomatic arch
○ A2: Lateral orbital wall
○ A3: Inferior orbital rim
● Type B: Classic tetrapod fracture involving all four
processes of the zygoma
● Type C: Complex fracture with comminution of zygomatic bone
Name the weakest bone involved in the ZMC fracture.
Orbital floor
Rotation of the ZMC is due primarily to the pull of which muscle?
The masseter muscle
What is the gender distribution of ZMC fractures?
Male-to-female: 80%:20%
Name the common approaches to the zygomaticofrontal buttress.
● Lateral brow incision
● Upper blepharoplasty incision
● Hemicoronal incision
● Existing lacerations
What contraindications exist for the immediate
repair of orbital floor fractures?
● Globe rupture ● Hyphema ● Retinal detachment ● Traumatic optic neuropathy ● Involvement of the patient's only seeing eye (relative contraindication)
What physical examination findings would necessitate urgent surgical intervention of an orbital floor fracture?
Muscular entrapment (particularly in children), soft tissue herniation with nonresolving oculocardiac reflex, significant soft tissue emphysema leading to increased intraocular pressure, and visual impairment
How should traumatic retrobulbar hematoma with vision loss initially be managed?
Lateral canthotomy and inferior cantholysis
What pharmacologic agents can be used to help manage high intraocular pressure?
IV mannitol, acetazolamide, corticosteroids, ophthalmic β-blockers, ophthalmic α-agonists, cholinergic medications
What are common findings associated with
retrobulbar hematoma?
Eye pain, proptosis, chemosis, diplopia, increased intraocular pressure, tense globe, decreasing visual acuity, loss of direct pupillary light reflex and ophthalmoplegia,
papilledema
What is the gold standard for diagnosis of inferior rectus or oblique muscle entrapment after orbital
floor fracture?
Forced duction test
What is the gold standard test to confirm carotid-
cavernous fistula after orbital trauma?
Angiogram
Describe the hydraulic and buckling theories with
respect to the pathogenesis of orbital floor fractures.
● Buckling theory: Fracture occurs as result of transmission
of force directly to the orbital floor via the orbital rim.
● Hydraulic theory: Fracture occurs due to transfer of kinetic
energy to the orbital floor via the noncompressible orbital
soft tissue.
V2 division trigeminal nerve paresthesia is a
common finding in which type of facial fracture?
Orbital floor fractures
What is the most common complication of orbital
floor fracture repair?
Inferior orbital nerve injury
Approximately what percentage of the orbital
floor must be involved for enophthalmos to occur
after orbital floor fracture?
More than 50%
Name the structures that pass through the
superior orbital fissure.
Oculomotor nerve (III), trochlear nerve (IV), abducens nerve (VI), V1 divisions of the trigeminal nerve, ophthalmic vein
Describe the signs and the treatment of traumatic
optic neuropathy.
● Marcus Gunn pupil (relative afferent pupillary defect), central scotoma, and decreased visual acuity
● Steroids and/or surgical decompression is sometimes used, but a high rate of spontaneous recovery may obviate the need for intervention.
In the setting of traumatic optic neuropathy from
orbital fracture, what fracture type is more
favorable for visual recovery?
Absence of fracture (most favorable) > anterior orbital
fracture > posterior orbital fracture (least favorable)
Describe common findings associated with orbital apex syndrome.
Ophthalmoplegia from damage to the oculomotor, trochlear, and/or abducens nerves (CN III, IV, and VI), mydriasis from damage to oculomotor nerve (CN III), pain/anesthesia
of the eye and forehead from damage to the ophthalmic branch of the trigeminal nerve (V1), and decreased visual acuity from optic nerve dysfunction (CN II)
What is the orbital septum?
An extension of the periosteum at the orbital rim that forms the anteriormost border of the orbital contents. It blends
with the levator palpebrae superioris in the upper lid, and the tarsal plate in the lower lid.
Describe common approaches to the inferior
orbital rim and orbital floor.
● Transconjunctival approach: An incision inferior to the tarsal plate for preseptal approach and incision just anterior to the fornix for postseptal approach. Carries risk
for entropion
● Subciliary (blepharoplasty) approach: An incision 1 to 2 mm
below the gray line of the lower eyelid, high risk of
ectropion, and greater technical difficulty
● Subtarsal/mid-eyelid approach: Straightforward approach, direct access to floor, carries risk of ectropion, and has a
visible scar
● Infraorbital approach: Straightforward approach, most visible scar, associated with greater postoperative edema,
and carries risk of ectropion. For the aforementioned
reasons, the infraorbital approach has fallen out of favor compared with the first three orbital approaches unless
an existing laceration is already present in this area.
