Open Collections

Gilmore, Kevin

University of British Columbia

Treatment of head and neck cancers in the mandible and surrounding tissues may necessitate oncological resection. This leaves a loss of continuity in the mandible, creating deficiencies in function and aesthetics. Reconstruction of the mandible is often completed with an autologous bone and tissue transplant from the fibula. The fibula is harvested to maintain viability, cut into segments, and secured into the defect. Traditionally, this is completed freehand, with surgeons using a trial-and-error approach to shaping and positioning the segments. This technique is time-intensive, and its accuracy is dependent on surgeon skill. To overcome these issues, a technique was developed in which 3D printed cutting guides for the mandible and fibula are created based on CT scans taken up to 4 weeks prior, creating potential for the guides to become ineffective due to cancer growth prior to surgery. To overcome the challenges of the 3D guides, the ISTAR group at UBC developed a system to facilitate day-of intraoperative surgical planning and guidance. However, the positioning device in this system utilized an ’all or nothing’ locking mechanism which did not allow for precise or iterative segment positioning. Therefore, the main aims of this thesis are to develop and validate a micropositioning surgical device for positioning of the fibula segments in the reconstruction. After fabricating this device, we conducted verification testing, demonstrating 0.48 ± 0.51, 0.15 ± 0.63, and 0.02 ± 0.71 mm segment positioning accuracy in each translational DoF. The rotational accuracy was shown to be -0.13 ± 4.53, 0.82 ± 2.41, and -0.51 ± 1.64 deg in each rotational DoF. In collaboration with Melissa Yu, testing with 3 ENT surgeons was conducted on anatomical models. The results of this test demonstrated a 0.77 ± 0.05 full reconstruction Dice score, a 1.79 ± 0.79 mm HD95, and a 1.16 ± 0.26 mm overlap deviation. When isolating the fibula reconstruction from the mandible, the Dice score and HD95 improved to 0.83 ± 0.03 and 0.86 ± 0.29 mm respectively. The accuracy of reconstruction is comparable to literature for 3D printed guides, with the addition of day-of-surgery planning and improved intraoperative flexibility.

Text

2024-01-08

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87144

Biomedical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/