Page 145 - Advanced concepts in orbital wall fractures

quick, but not accurate enough. Method SA has the best combination of time efficiency (mean 146 seconds, SD 16), accuracy (mean 0.24 cc, SD 0.27), perfect reproducibility, and ease of use. Although method SAA is more time-consuming and less accurate, it does show better potential in measuring increased orbital volume after orbital wall fracture, due to the ability to manually adjust. The method is not yet validated for this purpose.
In chapter 3, volume and contour differences between unaffected orbital cavities are measured using method SA. Mirroring is an important step in diagnostics and virtual preoperative planning and relies on the assumed symmetry of the orbital walls. The measurements are performed on the CT scans of 100 patients without orbital pathology. The mean difference between both orbital cavities is 0.44 cc (SD 0.31) or 1.59 % (SD 1.10 %). There is also a high similarity in orbital contour with an absolute mean difference of 0.82 mm (SD 0.23). These differences are clinically insignificant and will not lead to fundamental errors in planning the orbital reconstruction. The mirroring technique is therefore considered very useful to plan the best-fit position of the implant prior to orbital reconstruction.
Advanced 3D diagnostics and preoperative planning ensure optimal
preparation for the surgeon. During the virtual surgery, assessment of
the fracture, the anatomical landmarks, the implant size, and the best
position of the implant is possible. In the complete workflow of CAS, intraoperative navigation is used for real-time feedback during the orbital reconstruction. Chapter 4 demonstrates that the use of preoperative
virtual planning, without intraoperative navigation, improves the position C of the implant. In this study, orbital reconstruction is performed on ten 8 cadavers with intentionally created, complex, orbital wall fractures. The
surgeon can consult the preoperative plan and the CT scan on a screen in the operating theatre. The actual implant position is compared to the ideal implant position. Translation and the rotations yaw and roll improve significantly (p<0.05). The preoperative plan can be considered the most important step in CAS. Another benefit of preoperative planning is that it enables postoperative analysis.
Summary in English and Dutch
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