Three-Dimensional Planes of Reference for Orbital Fractures

Abstract

Introduction: Three-dimensional planes of reference for orbital fractures (3D-PROF) is a technique for isolating segments of the orbital cavity for 3D analyses. Method: Using 3D-PROF, the orbital floor, and medial wall were isolated on Meshlab (National Research Council, Pisa, Italy).( 1)Hemi-facial segmentation: Removal of contralateral skull using the mid-sagittal plane(2)Caudal-facial segmentation: Removal of facial bones below the plane across the infraorbital foramen and external acoustic meatus(3)Superolateral segmentation: Removal of orbital roof and lateral wall using a plane across the inferior orbital fissure, external acoustic meatus, and posterior clinoid process(4)Posterior skull segmentation: Removal of skull segment posterior to the orbital cavity using the orbital apex as reference point A pilot study was conducted to evaluate the interobserver variability of 3D-PROF. Facial computed tomography scans of 20 patients with normal unilateral orbit were randomly selected. Four observers performed 3D-PROF to isolate the orbital floor.The isolated orbital segments are evaluated for:(1)Total surface area(2)Preservation of 3 critical landmarks (infraorbital rim, posteromedial bulge, inferior orbital fissure) Results: The intraclass correlation coefficient for the total surface area of the resultant bony segment was excellent (0.85, confidence interval 0.707-0.934, P < 0.01). All landmarks achieved a rate of preservation of at least 90% (18/20) for the observers, except for the infra-orbital rim where 1 observer achieved 85% (17/20). Conclusion: Three-dimensional planes of reference for orbital fractures, is an easy and reproducible technique for isolating regions of interest of the orbital cavity for preoperative planning.