The zygoma bone has two major components, the zygomatic arch and the body. The arch forms the inferior and lateral orbit, and the body forms the malar eminence of the face. Direct blows to the arch can result in isolated arch fractures. These present clinically with pain on opening the mouth secondary to the insertion of the temporalis muscle at the arch or impingement on the coronoid process. More extensive trauma can result in the “tripod fracture,” which consists of fractures through three structures: 1) the frontozygomatic suture; 2) the maxillary process of the zygoma including the inferior orbital floor, inferior orbital rim, and lateral wall of the maxillary sinus; and 3) the zygomatic arch. Clinically, patients present with a flattened malar eminence and edema and ecchymosis to the area, with a palpable step-off on examination. Injury to the infraorbital nerve may result in infraorbital paresthesia, and gaze disturbances may result from injury to orbital contents. Subcutaneous emphysema may be present.
Management and Disposition
Maxillofacial CT best identifies zygoma fractures. Treat simple zygomatic arch or tripod fractures without eye injury with ice and analgesics and refer for delayed operative consideration in 5 to 7 days. Refer extensive tripod fractures or those with eye injuries urgently. Decongestants and broad-spectrum antibiotics are generally recommended for tripod fractures, since the fracture crosses into the maxillary sinus. Fractures with blood in the sinus should also be treated with antibiotics.
Zygomatic Arch Fracture. Axial cut of a facial CT that reveals a minimally depressed zygomatic arch fracture. (Photo contributor: Lawrence B. Stack, MD.)
Tripod fractures are often associated with orbital and ocular trauma. Palpate the zygomatic arch and orbital rims carefully for a step-off deformity.
Examine for eye findings such as diplopia, hyphema, or retinal detachment. Check for infraorbital paresthesia indicating injury or impingement of the 2nd division of cranial nerve V.
Visual inspection of the malar eminence from several angles (especially by viewing the area from over the head of the patient in the coronal plane) allows detection of a subtle abnormality.
Zygomatic Arch Fracture. Patient with blunt trauma to the zygoma. Flattening of the right malar eminence is evident. (Photo contributor: Edward S. Amrhein, DDS.)
Tripod Fracture. The fracture lines involved in a tripod fracture are demonstrated in this three-dimensional CT reconstruction. (Photo contributor: Patrick W. Lappert, MD.)