Page 51 - Advanced concepts in orbital wall fractures

Introduction
Clinical decision making in the management of orbital wall fractures is
challenging because of existing controversies1-3. Diagnostics are important
in assessing the severity of the fracture. Owing to the loss of bony support,
the orbital volume increases and the potential result is that the orbital
contents protrude into adjacent spaces. This can cause functional and
aesthetic sequelae, such as diplopia and enophthalmos4. The increase in C volume after orbital fractures is considered the main cause of posttraumatic 3 enophthalmos, especially if the fracture is located in the posterior part
of the orbital floor or medial wall5,6. In severe cases, it is necessary to perform an orbital reconstruction. The objective is to reconstruct the bony contours, restore the orbital anatomy and, hence, decrease the increased orbital volume, support the globe, and optimise function7.
Orbital surgery is difficult because the pyramidal shape of the cavity causes limited access, poor visibility, and potential complications. Technological developments in the planning and execution of treatment have led to a more accurate and predictable surgical outcome8-10. Computer-assisted surgery (CAS) has proved to be a helpful tool to support the surgeon in diagnostics and treatment11-13. The surgeon can assess the severity of the fracture by collecting digital data, virtually plan the operation, and use navigation during surgery without additional radiation exposure for the patient. It improves the accuracy of the reconstruction and can shorten the operation time for orbital wall repair.
The diagnostic and preoperative phase is fundamental in the process of CAS. Several years ago, a virtual mirroring technique was introduced and has been frequently applied in diagnostics and virtual planning. Segmentation of the unaffected side and mirroring it as an overlay over the affected side produces easy-to-understand information on the dislocated bony fragments and creates an ideal virtual template for reconstruction14-16. The idea behind the tool is that the unaffected side is a good representation of the pretraumatised state of the affected side. Several studies have reported that most people have close to perfect symmetry in general17-19.
Virtual mirroring
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