Redesign and treatment planning orbital floor reconstruction using computer analysis anatomical landmarks.

Abstract

Orbital floor fractures are one of the most commonly encountered maxillofacial fractures due to their weak anatomical structure. Restoration of the orbital floor following a traumatic injury or a tumor surgery is often difficult due to inadequate visibility and lack of knowledge on its anatomical details. The aim of this study is to investigate the locations of the inferior orbital fissure (IOF), infraorbital groove (G), and infraorbital foramen (Fo) and their relationship with the orbital floor using a software. Measurements from the inferior orbital rim (IOR) using the Fo, the IOF, G, and the optic canal (OC) were calculated in 268 orbits as reference points. The surgical landmarks from the G and the OC, the G and the IOF, the G and the intersection point were measured as 31.6±6, 12.9±4, and 12±5mm, respectively. The mean distances between the G and the IOR, the Fo and the IOF, and the Fo and the OC were found as 8.3±2.1, 28.7±3.5, and 53.6±5.9mm, respectively. The mean angles were calculated as OC-IOF-G 68.1°±16.4°; intersection-G-IOF as 61.4°±15.8°; IOF-OC-G as 19°±5.5°; OC-G-intersection as 31.5°±11.9°, G-intersection-OC as 129.5°, IOF-intersection-G as 50.5°. Furthermore, variable bony changes on the orbital floor which may lead to the differences at intersection point of the G and Fo were determined. In 28 specimens (20.9%), unilateral accessory Fo (AcFo) was present. In 27 specimens, AcFo was situated supermaedially (96.4%) on the main aperture. In one specimen, two intraorbital canals and Fo emerged from different points and coursed into different apertures. The measured mean distances of the AcFo-IOR and the AcFo-Fo were as 7±2 and 7.3±3.2mm, respectively. The primary principle in the oculoplastic treatment of orbital floor reconstructions must be repositioning the herniated orbital aperture by maintaining the infraorbital artery and the nerve in the orbital floor. The IOF and the G were recommended as the more reliable oculoplastic surgical landmarks for identifying the orbital floor. To avoid pinching of the orbital floor structures, the triangle (IS-G-IOF) should be equilateral with an exigence of a 70° angle within it. Among each distance of the intersection-IOF, IOF-G, G-intersection should be equal. With the help of certain software, this study made possible to investigate the variability of the orbital floor structures, observe the variety in measurements and calculate the parameters which are crucial in implementing personalized reconstruction and implanting support.