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Purpose: The existence of isolated bilateral zygomatic arch fractures has been debated by plastic and craniofacial surgeons. To date only one published case report on this fracture pattern exists. The purpose of this study was to systematically review patients with facial fractures presenting to a large urban trauma center to determine the incidence of isolated bilateral zygomatic arch fractures, their etiologic mechanism, and associated injuries.
Methods: An institutional review board-approved retrospective review of all patients presenting with facial fractures diagnosed by CT imaging at the R Adams Cowley Shock Trauma Center in Baltimore, Maryland from February 1998 to December 2009 was conducted. ICD-9 codes 802.4 (Closed fracture of malar and maxillary bones) and 802.5 (Open fracture of malar and maxillary bones) were used to identify patients presenting with bilateral zygoma fractures. All identified patients’ CT scans of the face were reviewed by the authors. Patients with bilateral zygomatic arch fractures without other facial fractures were identified from this subset of the study population and their medical charts were extensively reviewed to assess outcomes and demographic information, including age, gender, mechanism of injury, associated injuries, Injury Severity Score (ISS), and admission Glasgow Coma Scale (GCS).
Results: Of 72,299 patients admitted to the trauma center during the study period, 2,047 (2.83%) were confirmed to have suffered at least one zygoma fracture, either isolated, or in combination with other facial fractures. Of these, 1,890 (92.3%) were unilateral and 157 (7.7%) were bilateral. Five patients (0.24% of patients with any zygoma fracture, 3.18% of patients with bilateral zygoma fractures) were found to have isolated bilateral zygomatic arch fractures. Neither Le Fort level fractures nor fractures to any other facial bone were present in any patient. However, all five patients had evidence of associated skull impact with at least one skull fracture and at least one skull base fracture. Four patients had bilateral skull base fractures, and four patients had intracranial hemorrhage. Admission GCS values for patients with isolated bilateral zygoma fractures (average 8.2, range 6-14) were significantly lower than admission GCS values of all other patients (average 12.2, range 0-15) presenting with facial fractures during the study period (student’s t-test, two-sided, p-value = 0.01). In terms of disposition, one patient expired, one was admitted to an inpatient rehabilitation unit, and three were admitted to traumatic brain rehabilitation units.
Conclusions: Isolated bilateral zygomatic arch fractures, although extremely rare, are a unique pattern of facial injury. Given that all patients in this series suffered basilar skull fractures, our findings strongly suggest skull impact as the inciting mechanism of injury with anterior force transmission through the skull base and zygomatic arches. Cadaveric studies are planned to evaluate this mechanistic hypothesis. The prognosis for this fracture pattern is grim given the severe intracranial injuries associated with it. Aggressive evaluation for concomitant injuries to the head, brain and spinal cord should be undertaken in any patient presenting with isolated bilateral zygomatic arch fractures.