title: Does intraoperative navigation restore orbital dimensions in traumatic and post-ablative defects?
abstract: BACKGROUND
  The outcomes of the reconstruction of post-ablative and post-traumatic orbital defects are often unpredictable when considering the restoration of the orbital dimensions. Intraoperative navigation offers the surgeon visualization of bony landmarks via comparison to preoperative computed tomography, aiding in bony reduction and implant placement. The purpose of this study was to assess whether intraoperative navigation-guided orbital reconstruction re-establishes orbital volume and globe projection in subjects with post-ablative and post-traumatic orbital defects.
  
  
  METHODS
  The investigators initiated a retrospective cohort study and enrolled a sample of subjects that underwent primary or secondary reconstruction for unilateral orbital deformities secondary to traumatic injury or tumour surgery. Pre- and post-operative orbital volume and globe projection were measured using Analyze (Mayo Clinic Biomedical Imaging Resource, Rochester, MN, USA). A matched pairs t-test was used to assess the difference in pre- and post-operative orbital volume and globe projection.
  
  
  RESULTS
  Twenty-three subjects underwent intraoperative navigation-guided orbital reconstruction. The mean difference in orbital volume and globe projection between the non-operated orbit and operated orbit in the post-operative period was -1.3 cm(3) and 2.4mm respectively. Both final measurements were within the margin of error of clinically noticeable enophthalmos. The mean absolute difference in orbital volume and globe projection between the pre- and post-operative period was 5.1 cm(3) (p=<0.001) and 4.1mm (p=<0.001) respectively.
  
  
  CONCLUSIONS
  The results of this study suggest that orbital reconstruction using intraoperative navigation is effective in establishing normal orbital volume and globe projection in post-traumatic and post-ablative defects, therefore restoring the orbit and globe to pre-traumatic and pre-ablative conditions.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Oregon Health and Science University, Portland, OR, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Markiewicz
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Dierks
authors.forename: R Bryan
authors.initials: RB
authors.lastname: Bell
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005094:Exophthalmos / Q000601:surgery; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007430:Intraoperative Care / Q000379:methods*; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D009915:Orbit / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery*; D009917:Orbital Fractures / Q000601:surgery; D020273:Orbital Implants; D009918:Orbital Neoplasms / Q000601:surgery; D019919:Prosthesis Implantation / Q000379:methods; D019651:Plastic Surgery Procedures / Q000379:methods*; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods*; D036542:Tomography, Spiral Computed; D016896:Treatment Outcome; D055815:Young Adult