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Digital implant data customisation and creation of virtual reference points in orbital trauma planning and navigation-assisted surgery — a case series

      Background: Navigation-assisted orbital surgery has been shown to improve surgical outcome. Implant-oriented navigation technique has also been described. However, introduction of physical markers in prefabricated implant may inadvertently cause modification and suboptimal placement. We describe a method of implant data customisation and creation of virtual reference points during surgical planning in navigation surgery.
      Methods: From October 2015 to June 2016, twelve patients who sustained orbital blowout fracture were treated using this method. Uninjured contralateral orbit was used as reconstruction reference by using iPlan CMF (Version 3.0, BrainLab, Germany). The optimal implant position and size were determined to achieve best possible fit to the defect area, followed by implant data customisation using CloudCompare (Version 2.6.1, CloudCompare). Following data import, three virtual reference points in triangular fashion were created for the implant to serve as surgical reference points. The orbit was approached via a subciliary incision. Physical implant was carefully pre-adjusted to exact its virtual manipulation prior to the surgery and positioned under all four multiplanar views. Postoperatively, the accuracy of implant placement was assessed by image fusion. Clinical assessment for diplopia and enophthalmos was also carried out.
      Findings: Image fusion showed an ideal positioning and consistent surgical reproduction according to the virtual planning. Slight overcorrection in the anterior extension below the globe is seen in a few cases. However, its clinical correlation cannot be established. No patients developed any untoward diplopia and enophthalmic complications.
      Conclusion: Digital implant data customisation and creation of virtual reference points in orbital trauma planning may further improve orbital navigation-assisted surgery.