Effects of infraorbital nerve's anatomical course on the fracture pattern of the orbital floor

In this study, details of the infraorbital nerve's (ION's) anatomical course variants were compared using computed tomography (CT), and relationships between the variants and fracture patterns in the orbital floor were investigated. Fifty-two normal individuals and 50 patients with unilateral isolated orbital floor fractures were enrolled in this study. Four measurements in normal individuals and five measurements in fracture patients were obtained in parasagittal sections. The anatomical variations of the ION were categorized into three types according to the classification by Ferences et al. Among the normal individuals, 42 orbits were classified as type 1 ION, 48 orbits as type 2, and 14 orbits as type 3. The distance from the inferior orbital rim to the upper border of the inferior orbital foramen and the length of descension portion of the ION in type 1 ION were significantly shorter than in type 2 and type 3 IONs. In patients with orbital floor fractures, the distance from the inferior orbital rim to the upper border of the inferior orbital foramen was positively correlated with herniation level of bone and soft tissue. The ION had three anatomical variants according to the degree of descension in the anterior portion of the orbit. When fracture of the orbital floor occurs in patients with type 1 ION, inferior displacement of the fractured orbital bone and orbital soft tissue may be less severe than in patients with other ION types.