Page 70 - Advanced concepts in orbital wall fractures

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Chapter 4
virtual planning) have never been separately assessed in CAS studies. Our hypothesis was that preoperative virtual planning, without intraoperative navigation, improves the position of the implant and may even be the most important step in the process of CAS.
Materials and methods
Materials
This cadaveric cohort study was not subject to consent by the local ethics committee, and was performed in accordance with the Declaration of Helsinki. Ten preserved and labelled human cadaver heads were obtained from the Department of Anatomy, Embryology and Physiology of the Academic Medical Center (AMC) Amsterdam. To prepare each orbit for surgery, a transconjunctival approach was used to gain sufficient visibility of the orbital floor and medial wall. Large defects (Jaquiéry class III/IV) were created in the orbital floor and/or medial wall using piezoelectric surgery (Mectron, Carasco, Italy)20. Due to sinus pathology (osteoma) one of the twenty orbits had to be excluded.
Computed tomography (CT) scans were made at the beginning of the study (intact orbital cavities), after creation of the orbital fractures, and postoperatively to check the obtained implant position. CT scans were acquired by the Siemens Sensation 64 (Siemens Healthcare, Forchheim, Germany). The scans parameters were: slice collimation 20×0.6 mm, 0.75 mm slice thickness, 0.4 mm slice increment, 512×512 matrix, 120 kV, 350 mAs, pitch 0.85, FOV 30 cm, hard-tissue convolution kernel H70s, and window W1600 L400.
Preformed orbital titanium mesh plates (KLS Martin, Tuttlingen, Germany) were used for all orbital reconstructions. These plates were imported as STL files in the planning program (iPlan software version 3.0.5; BrainLAB AG, Feldkirchen, Germany) to perform the virtual reconstruction. The optimal implant position was determined by a technician and two surgeons based on the STL file of the implant, the pretraumatised scan, and the preoperative scan.