Orbital volumetric analysis: Clinical application in orbitozygomatic complex injuries

Fifteen patients with unilateral orbitozygomatic complex fractures and five with bilateral injuries were analyzed with respect to the differences in orbital volume between the affected and the uninjured, or other, side. The study was conducted using the ALLEGRO Workstation and software package from ISG Technologies, which was capable of calculating volume partitions from either axial or coronal images. Patients without postoperative enophthalmos demonstrated a maximum volume difference of 3.8%; those with enophthalmos demonstrated differences of 4% or greater. The Critical Volume Difference at which enophthalmos becomes clinically apparent (whereby the orbital-corneal distance measured by Hertel exophthalmometry is greater than 3 mm on the affected side) is in the range of 4% to 5%. Volume analysis of the orbits by manipulation of the computed tomography data may allow a better understanding of changes in orbital configuration, which can result in better-directed primary and secondary reconstructions.