XRAYS FOR ZYGOMATICOMAXILLARY COMPLEX (ZMC / “TRIPOD”) FRACTURES
Introduction
Zygomaticomaxillary complex (ZMC, or “tripod”) fractures disrupt the zygoma and its articulations with the maxilla, frontal bone (lateral orbital rim) and zygomatic arch (temporal process).
In emergency practice clinicians must distinguish simple, non‑displaced injuries suitable for conservative care from complex fractures that need CT, specialist review and operative planning.
Plain radiographs (various occipitomental / Waters variants, submentovertex, Townes and tangential arch views) are still taught and used in some urgent‑care settings but have limited sensitivity for the full extent of facial fractures.
CT maxillofacial (thin‑slice facial bones with coronal and sagittal reformats ± 3D) is the investigation of choice when a complex injury is suspected (see NICE NG232). Follow local radiology protocols for any plain‑film series used.
Anatomy and the ZMC / “tripod” fracture
- The zygoma forms the malar prominence and contributes to the lateral orbital wall and floor.
- Major articulations of the zygoma:
- Zygomaticomaxillary buttress (anterior).
- Zygomaticofrontal suture / lateral orbital rim (superior).
- Zygomatic arch (posterior / temporal process).
- A ZMC (tripod) fracture typically involves disruption of two or more of these articulations and may include maxillary sinus wall fractures and orbital floor or medial wall defects.