title: Clinical implications of orbital volume change in the management of isolated and zygomaticomaxillary complex-associated orbital floor injuries.
abstract: BACKGROUND
  Orbital floor injuries can occur in isolation or in association with zygomaticomaxillary complex fractures. Volumetric computed tomographic measurements of affected orbits are investigated for utility in guiding management in these two groups.
  
  
  METHODS
  The medical records of all patients with craniomaxillofacial injuries (2003 to 2005) were reviewed. Of 522 total patients, 45 patients had isolated orbital floor fractures, 13 of whom underwent repair (29 percent), and 64 had zygomaticomaxillary complex fractures, 36 of whom underwent reconstruction (56 percent) and 10 of whom underwent orbital floor repair (16 percent). Radiographic criteria for floor exploration included 50 percent area fracture in isolated injuries and 10-mm estimated zygomaticomaxillary complex compression in zygomaticomaxillary complex-associated floor injuries. Volume measurements of the affected orbits were obtained and compared with the uninjured contralateral orbit.
  
  
  RESULTS
  Before treatment in the operative zygomaticomaxillary complex group, there was an average decrease in orbital volume of 18.3 percent. In the isolated orbital floor group, there was an average increase in orbital volume of 28.3 percent.
  
  
  CONCLUSIONS
  Zygomaticomaxillary complex-associated orbital floor injuries can be compressive injuries associated with loss of volume, whereas isolated injuries generally result in volume expansion. Radiographic criteria are often considered in the decision to proceed with orbital floor exploration to avoid late enophthalmos. The literature suggests that a 20 percent change in orbital volume results in perceptible deformity. Therefore, a radiographic criterion of 50 percent floor area (28 percent volume increase) in isolated injuries may be too stringent; an estimated 10 mm of compression (18.3 percent volume change) is a reasonable operative criterion for floor exploration in zygomaticomaxillary complex-associated injuries.
authors.affiliation: Durham, N.C. From the Interdisciplinary Craniofacial Imaging Laboratory and the Department of Biomedical Engineering, Duke University, and the Division of Plastic, Reconstructive, Maxillofacial, and Oral Surgery and the Department of Radiology, Duke University Medical Center.
authors.forename: Amir
authors.initials: A
authors.lastname: Tahernia
authors.forename: Detlev
authors.initials: D
authors.lastname: Erdmann
authors.forename: Keith
authors.initials: K
authors.lastname: Follmar
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Mukundan
authors.forename: Jason
authors.initials: J
authors.lastname: Grimes
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Marcus