Page 61 - Advanced concepts in orbital wall fractures
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                                Table 3 Average and maximum volume differences in present study compared with other studies.
n Average difference
Maximum difference
Virtual mirroring
  mL % mL %
 Present study Alinasab et al.32 Forbes et al.30 Felding et al.31
100 0.44 18 0.55 21 0.43 11 0.77
1.6 1.65 5.8 2.5 1.4 6.6 1.8 1.95 8.0 3.1 1.91 8.7
 It should be noted that in this study distance maps were created by C3 mirroring the complete skull and matching the skull and the orbital
volumes using voxel-based matching of the cranial base21,22. This method
was chosen because it is extremely difficult to identify a true median plane
to mirror the orbital volume35,36. It is difficult to point out exactly where the differences in the bony contour occur. In a clinical setting, it is often necessary to perform manual adjustments to achieve a good overlay of the mirrored orbital cavity on the unaffected side.
Mirroring can be performed only in patients presenting with unilateral pathology. In most cases, deformities or injuries are unilateral. Nevertheless, for bilateral pathology or trauma, it is possible to use an average orbital contour by importing an STL model of an orbit and adjusting it to patient-specific conditions.
Perfect restoration in symmetry does not necessarily result in a desired clinical outcome, and a suboptimal anatomic reconstruction does not by definition produce bad functional results. In addition to volume and contour, disorganisation of the orbital soft tissue (e.g., fat atrophy or muscle adhesions) is an important third factor in the final functional and aesthetic outcome7,37,38. Nonetheless, as shown by the literature, segmentation and mirroring tools are an important starting point for diagnostics and for planning a perfect orbital reconstruction.
The present study has some limitations. The 100 CT scans used for this study were obtained from patients examined in one hospital. Control for ethnicity was not incorporated in this study, so the sample might not be representative of a general population. Because of the nature of the study,
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