Trauma zygomaticomaxillary complex (ZMC) and orbital fractures

Question 1

A ZMC (“tripod”) fracture involves which structures?

Answer 1

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)

Question 2

In ZMC fractures, what usually causes restricted

mandibular opening?

Answer 2

Impingement of the zygomatic arch on the coronoid process and temporalis muscle

Question 3

List surgical complications associated with ZMC

fracture repair.

Answer 3

Lid malposition (ectropion, entropion), persistent diplopia,
facial and malar asymmetry, plate palpability, malunion/
nonunion, enophthalmos, cheek numbness (V2), and blindness (extremely rare)

Question 4

What approaches are the most appropriate for an isolated zygomatic arch fracture with no comminution?

Answer 4

Gilles approach or Keen approach

Question 5

What is the most prominent portion of the ZMC, and where is it located?

Answer 5

Malar eminence located 2 cm inferior to the lateral canthus

Question 6

Describe the Zingg classification of ZMC fractures.

Answer 6

● 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

Question 7

Name the weakest bone involved in the ZMC fracture.

Answer 7

Orbital floor

Question 8

Rotation of the ZMC is due primarily to the pull of which muscle?

Answer 8

The masseter muscle

Question 9

What is the gender distribution of ZMC fractures?

Answer 9

Male-to-female: 80%:20%

Question 10

Name the common approaches to the zygomaticofrontal buttress.

Answer 10

● Lateral brow incision
● Upper blepharoplasty incision
● Hemicoronal incision
● Existing lacerations

Question 11

What contraindications exist for the immediate

repair of orbital floor fractures?

Answer 11

● Globe rupture
● Hyphema
● Retinal detachment
● Traumatic optic neuropathy
● Involvement of the patient's only seeing eye (relative
contraindication)

Question 12

What physical examination findings would necessitate urgent surgical intervention of an orbital floor fracture?

Answer 12

Muscular entrapment (particularly in children), soft tissue herniation with nonresolving oculocardiac reflex, significant soft tissue emphysema leading to increased intraocular
pressure, and visual impairment

Question 13

How should traumatic retrobulbar hematoma with vision loss initially be managed?

Answer 13

Lateral canthotomy and inferior cantholysis

Question 14

What pharmacologic agents can be used to help manage high intraocular pressure?

Answer 14

IV mannitol, acetazolamide, corticosteroids, ophthalmic β-blockers, ophthalmic α-agonists, cholinergic medications

Question 15

What are common findings associated with

retrobulbar hematoma?

Answer 15

Eye pain, proptosis, chemosis, diplopia, increased intraocular pressure, tense globe, decreasing visual acuity, loss of direct pupillary light reflex and ophthalmoplegia,
papilledema

Question 16

What is the gold standard for diagnosis of inferior rectus or oblique muscle entrapment after orbital
floor fracture?

Answer 16

Forced duction test

Question 17

What is the gold standard test to confirm carotid-

cavernous fistula after orbital trauma?

Answer 17

Angiogram

Question 18

Describe the hydraulic and buckling theories with

respect to the pathogenesis of orbital floor fractures.

Answer 18

● 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.

Question 19

V2 division trigeminal nerve paresthesia is a

common finding in which type of facial fracture?

Answer 19

Orbital floor fractures

Question 20

What is the most common complication of orbital

floor fracture repair?

Answer 20

Inferior orbital nerve injury

Question 21

Approximately what percentage of the orbital
floor must be involved for enophthalmos to occur
after orbital floor fracture?

Answer 21

More than 50%

Question 22

Name the structures that pass through the

superior orbital fissure.

Answer 22

Oculomotor nerve (III), trochlear nerve (IV), abducens nerve
(VI), V1 divisions of the trigeminal nerve, ophthalmic vein

Question 23

Describe the signs and the treatment of traumatic

optic neuropathy.

Answer 23

● 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.

Question 24

In the setting of traumatic optic neuropathy from
orbital fracture, what fracture type is more
favorable for visual recovery?

Answer 24

Absence of fracture (most favorable) > anterior orbital

fracture > posterior orbital fracture (least favorable)

Question 25

Describe common findings associated with orbital apex syndrome.

Answer 25

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)

Question 26

What is the orbital septum?

Answer 26

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.

Question 27

Describe common approaches to the inferior

orbital rim and orbital floor.

Answer 27

● 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.