Page 88 - Advanced concepts in orbital wall fractures

86
Chapter 5
during operation17. Furthermore, the postoperative scan becomes obsolete because of the high image quality.
The purpose of this study was to assess the effect of intraoperative imaging on the accuracy of positioning of the implant in reconstructions of the orbital wall. The question is whether the possible advantages outweigh the disadvantages, such as radiation exposure, extra operating time, and costs. It is hypothesised, based on the results of earlier studies, that large deviations in position of the implant (such as placement below the posterior ledge or close to the optic nerve) may be noticed, but minor deviations in translation and rotation are difficult to observe and adjust18.
The aims of the study were threefold: first, is there a noticeable improvement in the position of the implant after intraoperative CT? Secondly, is the surgeon able to assess the deviation in position compared with that of the planned position? Thirdly, how many scans are needed before a satisfactory position has been reached?
Materials and methods
Materials
This cohort study was the last of a series of studies on orbital reconstruction13,19-21. The study was not subject to consent by the local ethics committee and was done in accordance with the directions of the Declaration of Helsinki. The Department of Anatomy, Embryology and Physiology of the Amsterdam UMC (location AMC) Amsterdam provided ten preserved and labelled human cadaver heads. Prior to the study, large defects (Jaquiéry class III/IV) were created in the orbital floor or medial wall (or both) of each orbit using piezoelectric surgery (Mectron, Carasco, Italy)22. Access was gained through a transconjunctival approach to achieve adequate visibility. Only 19 orbits could be used because there was an osteoma of the maxillary sinus in one of them.
Preformed orbital titanium mesh implants (KLS Martin, Tuttlingen, Germany) were used for the reconstructions. All CT scans were acquired