Page 79 - Advanced concepts in orbital wall fractures
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                                preoperative planned implant position with the intraoperative actual position in the operating theatre, to compare them and to directly make changes if necessary.
When comparing this study to an earlier cadaver study on navigation
by the same research group, similar comparable results in accuracy of
the implant positioning are published7. The reproducibility is better in
the navigation study group. Possible reasons for the similar results are
that by the simultaneous assessment of the operation field and the
multiplanar view on the computer screen, this may distract the surgeon
from the patient and the actual implant to the computer screen. If using
only the planning intraoperatively, the surgeon first evaluates the ideal C position and then tries to duplicate this to the actual implant position. 4 The surgeon may also rely more on the navigation and less on its own
experience. Another reason for the comparable results may be that navigation itself has small calibration and navigation errors which add up to the outcome16.
Cai et al. state that navigation minimises postoperative complications3. Their objective assessment of the actual implant position compared to the boundaries of the floor defect demonstrate an average of 3.24 mm vertical distance. To some extent this is comparable to our results. Essig et al. state that true-to-origin reconstruction was achieved in their study group18. Instead of standard preformed implants, individually bent titanium meshes were used. These results illustrate that navigation does have the potential to be extremely accurate.
The conditions of reconstruction on cadavers are different from actual surgery. Soft tissues are stiff, there is hardly any prolapse of intraocular fat and obviously no bleeding. In actual surgery, these factors are present and, in our opinion, add to the impaired visibility in the clinical situation. This would mean that preoperative virtual planning could be even more valuable in orbital reconstruction in a clinical setting than in cadavers. One of the advantages of a cadaver study is that the fractures in both groups are the same and the specimen can be assessed as often as necessary. The results in this study are based on the ideal implant position
Preoperative planning
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