Frontal Sinus Morphology: A Reliable Factor for Classification of Frontal Bone Fractures?

The frontal sinus shows a wide range of morphologic variations. The aim of this study was to evaluate the influence of frontal sinus size on fracture characteristics in frontal bone trauma.

In this cross-sectional study, data from patients with traumatic fractures of the frontal bone were retrospectively collected from the institution's database. Radiometric analysis of computed tomography and cone-beam computed tomography datasets was performed. Frontal sinus size was measured as variables of height, width, and depth. The secondary predictor was morphologic sinus type according to Guerram's classification: hyperplasia, medium size, hypoplasia, or aplasia of the frontal sinus. To determine outcomes, we classified fractures into the following categories: fracture isolated to the anterior table, combined fractures of the anterior and posterior tables, fracture isolated to the posterior table, and frontal bone fracture without sinus involvement. Further study variables were patients' demographic characteristics, combined midfacial fractures, orbital rim involvement, fracture displacement, and surgical approach. For statistical analysis, fracture types were assessed for frontal sinus metric size and morphologic type using bivariate tests with P < .05 defined as significant.

We enrolled 53 consecutive patients with a mean age of 35 years; male patients comprised 91%. Fracture types differed significantly in sinus width and height (both P < .001), as well as depth (P = .002). Frontal sinus morphology was hyperplastic in 66%, medium in 30.2%, and hypoplastic in 3.8%. Patients with a hyperplastic frontal sinus had an increased likelihood of isolated anterior table fractures (odds ratio, 6.0; P = .007) compared with medium-sized types. Fractures without sinus involvement were more likely in hypoplastic and medium types (P < .001).

The morphology of the frontal sinus determines the probability of fracture types from craniofacial trauma. Thus the frontal sinus size appears to be a major factor for frontal bone resistance to traumatic force impingement.