TRAUMA: Zmc # Flashcards
What is Tetrapod fracture / ZMC fracture?
ZMC fracture that involves 5 bones that articulates at 4 junction. 5 bones include the zygoma which articulates at 4 sutures to 4 other bones namely maxilla, tempral, sphenoid and frontal. Sutures include 1) zf suture
2) zs suture
3) zm suture
4) zt suture
Classification of ZMC fracture?
Zingg classification
Type A: Isolated zygomatic fracture
A1: ZA
A2: Lateral orbital wall (ZF)
A3: Inferior orbital rim
Type B: All four areas of tetrapod are involved in fracture in a monosegment
Type C: complex or comminuted fracture of Zygoma
Clinical presentation of ZMC #
Malar flattening
Widening of face
Enophthalmos
Step deformity at ZF,ZA, inferior orbital rim
Ocular dystopia (downward displacement of the pupil)
Antimongoloid slant of the eye
Reduced upward and downward gaze
Binocular Diplopia (extraocular muscle dysfunction)
Ecchymosis at buccal sulcus
Trismus
Paraesthesia
Investigations for Zygomatic fracture
Waters - sinuses, inferior orbital floor, lateral wall of the orbit
SMV - Zygomatic arch (ZA)
CT scan (bony window)- axial and coronal good for detailed evaluation of the fracture lines and assessment of orbital content or presence of orbital contents herniation
What are the indications of zmc treatment
Function
- trismus
- unresolving diplopia
- paraesthesia
Aesthetic
- malar asymmetry
- orbital deformity (orbital dystopia/ enophthalmos)
What are the indications of closed reduction
minimally displaced fracture
no orbital floor recon required
Is there a role for floor exploration in ZMC fracture
theory is that - ZMC fracture will have floor fracture as well.
However status of orbit can be visualized from CT and clinical assessment
- evidence of herniation on ct
- restricted upward gaze
is already a good indicator for orbital recons.
Generalized restricted eye movement is not indicated for exploration - d/t generalized edema
Inferior rectus ms entrapment needs exploration and recons - presents with restricted upward gaze
Therefore, exploration of orbital floor during ORIF of ZMC is not required.
What is the optimal timing for ORIF
Before onset of edema, or after several days once edema subsided. But no longer than 2-3 weeks to prevent bony union of the fracture segments
What is the downside of early ORIF?
Residual malar flattening, enophthalmos and asymmetry due to presence of edema immediately after injury making reduction difficult.
How to treat zygomatic arch fracture
Closed reduction
- Gillies approach
- Keens approach
Whats the sequence of ORIF in ZMC
Temporarily stabilize ZF suture first, then reduce ZM and inferior orbital floor. Fixation of ZM. Then go back to ZF for plate fixation. Finally reconstruct the floor.
How do you ensure adequate ORIF in ZMC fracture
By verifying accurate reduction of multiple areas of the sutures. in particular the ZF suture. For example, double check the ZM suture and infraorbital rim thru the intraoral approach, then verifying with the ZS suture.
What approaches would you choose for ORIF?
Thru existing laceration ZF -Lateral eyebrow -upper blepharoplasty - transconjunctival of lower lid with lat canthotomy ZM buttress - Intraoral vestibular approach Inferior orbital rim - Subcilliary - Subtarsal - Transconjunctival (can be improved with transcuruncular and lateral canthotomy) - Infraorbital For complex/comminuted fracture - Coronal
Complications of ORIF for ZMC
residual malar flattening and facial asymmetry enophthalmos vertical dystopia persistent diplopia trismus ankylosis at ZA and coronoid process infraorbital paraesthesia
Surgery related: traumatic optic neuropathy SOFs orbital apex syndrome retrobulbar hemorrhage Ectropion entropion
Which incision approach produce more risk pf ectropion?
Subcilliary
Midtarsal
Transconjunctival
