Relative difference in orbital volume as an indication for surgical reconstruction in isolated orbital floor fractures

Abstract

In orbital floor fractures, the estimation of the herniated orbital content in the maxillary sinus has traditionally been the dividing line between surgical and nonsurgical management. In this study, we evaluated whether a relative change in volume would function as an indicator for surgical versus nonsurgical treatment of orbital floor fractures. This was a follow-up study in patients with untreated unilateral isolated orbital floor fractures admitted to our department from March 2003 to April 2007. Patients were contacted by regular mail and invited to have a clinical eye examination. The volume of the orbital content was calculated digitally from the patients' computed tomography scans at the time of their injury. Eighteen subjects with no facial skeleton fracture were included for reference of orbital content volumes. Five of 23 patients showed 2 to 4 mm of enophthalmos, and only three of them had intermittent diplopia. No statistical correlation was found between the herniated volume and enophthalmos. No statistical correlation supporting the supposition that 1 mL of herniated orbital content would result in 1 mm of enophthalmos was found. The relative volume change between the fractured and nonfractured orbit in an individual does not appear to be a useful criterion for surgery. The importance of the herniated orbital tissue for the development of enophthalmos is unclear.

Keywords: Orbital floor fracture; blowout fracture; nonsurgical treatment; orbital volume.

Figure 1

The volume of the herniated orbital content.

Figure 2

Volume of the orbital content including the herniated orbital volume.

Figure 3

The posterior border in orbital volume measurements. Point 1, the exit of the optic nerve from the eye globe. Points 2 and 3 are the lateral edges of the superior orbital fissure on each side.

Figure 4

The anterior border in the orbital volume measurements. A1 and A2, the most distinct and widest laterodorsal duct of the lacrimal canal; B1 and B2, the lateral orbit limit.

Figure 5

Sagittal computed tomography slice where the fracture is considered largest. (A) Infraorbital margin, (B) anterior, and (C) the posterior part of the fracture.

Figure 6

Orbital discrepancy % (x) by herniated volume mL (y).

Figure 7

The analysis of the reproducibility of the orbital volume measurements. Mean value of the differences between the operators was 0.259 (standard deviation 1.397).

Figure 8

Herniated orbital volume (x) by enophthalmos (y).

Figure 9

Orbital discrepancy (x) by enophthalmos (y).

Figure 10

Correlation of herniated orbital volume and position of the fracture. Distance from margo to posterior part of the fracture (x) by herniated orbital volume (y).

Figure 11

Location of fracture from rim to the posterior edge of the fracture (x) by enophthalmos (y).

Figure 12

Content of the orbit marked for the volume measurement: (A) axial slide, (B) coronal slide, (C) sagittal slide.

Figure 13

The orbital volume.