Zygomaticomaxillary complex fractures

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Zygomaticomaxillary complex (ZMC) fractures are the second most common facial fractures after nasal bone fractures. As plastic and maxillofacial surgeons, a strong understanding of the anatomy, patterns, evaluation, and management of these injuries is imperative for achieving optimal functional and aesthetic outcomes. This blog post provides a comprehensive overview of key considerations.

Anatomy

The ZMC defines midface width and projection. It is formed by the zygoma and 4 surrounding bones – frontal, maxillary, temporal, and sphenoid. It provides insertion points for the masseter, temporalis, and zygomaticus major/minor muscles and is closely associated with the infraorbital nerve.

Epidemiology

  • Account for ~40% of midface fractures
  • Second most common facial fracture after nasal bones

Pathology

  • Direct blow to malar eminence
  • Disrupts zygoma anchoring via 3 main fracture components
  • Can cause trismus, infraorbital nerve injury/numbness

Evaluation

  • History: mechanism, numbness, trismus
  • Physical exam: 6 P’s of ZMC fractures
    • Periorbital swelling
    • Pain with gaze extremes
    • Perception: diplopia, subconjunctival hemorrhage
    • Paresthesia in V2 distribution
    • Projection: lack of malar prominence
    • Protusion: enophthalmos/exophthalmos
  • Ophthalmology assessment: orbital apex syndrome, other ocular injuries
  • CT scan with multiplanar reconstruction: gold standard imaging

Classification

  • Zingg et al. 1992 classification:
    • Type A: Incomplete zygomatic fracture
    • Type B: Complete monofragment zygomatic fracture
    • Type C: Multifragment zygomatic fracture

Management

  • Goals: restoration of anatomy, function
  • Closed reduction or open reduction/internal fixation
  • Rigid fixation with plates, screws to stabilize fractures
  • Soft tissue repair for coverage, aesthetics, ocular competence
  • Timing: emergent if severe sequelae, otherwise delayed 1-2 weeks

The table below provides a summary overview:

CharacteristicDescription
AnatomyZygoma + 4 surrounding bones; associated muscles/nerves
Epidemiology40% of midface fractures; 2nd most common after nasal
PathologyDirect blow to malar eminence; disrupts zygoma anchoring
EvaluationHistory, physical, ophthalmology assessment, CT scan
ClassificationZingg: Types A, B, C based on fracture components
ManagementAnatomical reduction; rigid internal fixation; soft tissue repair; timing

References:

Ranchod, A. I. (2023, September 14). Zygomaticomaxillary complex fracture: Radiology reference article. Radiopaedia. https://radiopaedia.org/articles/zygomaticomaxillary-complex-fracture-1?lang=gb

PlasticsFella. (2021b, December 12). Zygomaticomaxillary complex (ZMC) fractures. thePlasticsFella. https://www.theplasticsfella.com/zygomaticomaxillary-complex-fractures/

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