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Program Number: B292
Session Name: Poster Session

Augmented Reality Surgical Planning in Mandibular Reconstruction

Brandon Strong, PhD¹; Christian El Amm, MD²; Marc Metzger, MD³; Michael M Li, MD⁴; ¹University of California, Davis; ²University of Oklahoma; ³University Medical Center Freiburg; ⁴University of California Davis Medical Center

When indicated, ossoeocutaneous free tissue transfer for segmental mandibulectomy defects is the gold standard for reconstruction. Traditional free-hand reconstruction involves bending a plate to the native mandible, and subsequently contouring donor bone to reconstruct the defect using a template. While excellent outcomes can be achieved via free-hand technique, virtual surgical planning (VSP) has been shown to improve rates of bony union, decreased rate of wound complications, decrease length of admission, and reduce operative time. Disadvantages to VSP include delay to surgery, increased cost to health systems, and theoretical interference with bone margins. To address these concerns, some groups brought the VSP process “in-house”, using institutional three-dimensional (3D) printing and computer aided design (CAD) to create models and cutting guides. This approach can be limited by institutional availability and protocols (e.g. authorization to sterilize and use 3D printed models). Here, we present a novel augmented reality (AR) platform for mandibular reconstruction.

The Microsoft HoloLens is an AR headset that allows for projection and manipulation of virtual objects overlaid with a user’s native vision. Xironetic is a mixed reality VSP software company that utilizes the HoloLens. Using this platform, mandibular reconstruction was performed in three separate cases. In case one, an AR model of a two-segment fibular bone graft for mandibular reconstruction was projected and used to bend a titanium plate to the model (Figure 1a). In case two, an AR model of a fibular cutting guide was used to harvest bone for a fibular free bone graft while peroneal artery was visualized. Case three represents the most advanced use of the AR system. In this case, a patient with a history of oral cavity cancer status post resection and adjuvant radiation presented with osteoradionecrosis. CAD was performed in conjunction with KLS Martin, and a titanium plate and cutting guides milled. After fibula free flap was raised, the cutting guide was projected via AR, and a tracking anchor affixed to the proximal fibular bone to be discarded (Figure 1b). This allowed for real time and dynamic visualization of the virtual cutting guide in exact relation to the fibula. Under AR guidance, the previously planned osteotomies were made in otherwise standard surgical fashion (Figure 1c; view through the headset). The fibular bone segments were affixed to the plate in the leg prior to ischemia. The vascular pedicle was then divided, the complex affixed to the mandible and microvascular anastomosis performed (Figure 1d). Ischemia time was 65 minutes, and excellent bony contact was noted on initial post-op scan. 

These cases highlight the potential for AR in mandibular reconstruction, especially its capacity to address current limitations in VSP. Obviating the need for physically printed cut guides may significantly reduce time to surgery and decrease costs. Next steps in advancing this system will include in-house CAD, developing a platform for real-time VSP (allowing for modification of bone margins), and larger case series.

 

 

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