Tripod fracture

The tripod fracture, also called the zygomaticomaxillary complex or malar fracture, is composed of a set of three (actually 4) bone fractures. The first portion of the tripod fracture involves the maxillary sinus including the anterior and postero-lateral walls and the floor of the orbit. The second portion involves the zygomatic arch. The third portion involves the lateral orbital rim, usually including the lateral orbital wall, or the zygomaticofrontal suture. The term is actually not accurate as there is a fourth suture that can be involved: The sphenozygomatic suture between the sphenoid and zygomatic bones.

Cause

• Direct blow to malar eminence of the zygomatic bone

Signs and symptoms

• Facial bruising/swelling
• Flattened malar eminence
• Loss of facial sensation below orbit (infraorbital nerve involvement)
• Trismus / altered mastication
• Diplopia +/- ophthalmoplegia

Anatomy

The following suture lines are involved:

• Laterall wall of maxillary sinus
• Orbital rim +/- infraorbital foramen
• Orbital floor
• Zygomaticofrontal suture / zygomatic arch^[2][3]

Fractures of zygoma are the most common fractures of the upper cheek, the most common of which is the tripod fracture of zygomatic bone involving 3 separate breaks of bones of skull, through: 1. infraorbital foramen and canal to the infraorbital groove 2. zygomaticoparietal suture of lateral margin of orbit 3. zygomatic arch usually at its narrowest point, where the suture between the zygomatic process of temporal bone and temporal process of zygomatic bone occurs.

Treatment

Non-displaced or minimally displaced fractures may be treated conservatively. Fractures with displacement require surgery consisting of fracture reduction with application of plates and screws to keep the bone fragments in place. Gillie's approach is used for depressed zygomatic fracture.

Prognosis

The prognosis of tripod fractures is generally good. In some cases after surgery there may be facial asymmetry which might require reoperation.

References