Page 87 - Advanced concepts in orbital wall fractures

Introduction
Acquiring feedback about the position of the implant is important during reconstruction of the orbital wall1,2. In orbital surgery the overview of the
fracture and position of the implant are limited by herniation of orbital
fat and minimally invasive surgery3,4. Because of the complexity of the
surgery a relatively high percentage of the reconstructions result in the
implant being in an unfavourable position, or even needing revision
surgery5. Suboptimal positioning often leads to deviations in translation
and rotations, which might cause a serious increase in orbital volume and
related complications such as enophthalmos6-8. Intraoperative imaging
can be used to achieve an optimal position in these reconstructions9,
yet it is doubtful if subtle deviations in the planned position compared
with the achieved position can be assessed accurately on intraoperative
computed tomography (CT) imaging without the use of three-dimensional
advanced diagnostics, planning, or navigation, or all three combined. C
Apart from training, experience, and preoperative planning, the surgeon 5 could additionally rely on several methods of intraoperative evaluation
such as endoscopy and surgical navigation10-12. Although navigation
improves the position of the implant, it still has a certain degree of
inaccuracy and revision surgery could still be necessary, even with the use of expensive navigation equipment5,13. CT scans are therefore necessary to verify the position of the implant9. The major advantages of verification of the position during surgery are direct quality control and the ability to adjust a suboptimal position.
The usability and image quality of intraoperative CT scans have improved considerably. The use of mobile scanners limits extra operating time to about 15 minutes and cone beam (CB)CT scanners (40-80 μSv) reduce radiation compared to the conventional CT scanner (600-800 μSv)14. Several studies have confirmed the effectiveness of intraoperative imaging in the reconstruction of facial fractures, such as zygomatic fractures and extensive orbital fractures15,16. The multiplanar view of the intraoperative CBCT scan seems to be sufficient for diagnosing orbital fractures and possibly for the evaluation of the position of the implant
Intraoperative imaging
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