University of Twente Student Theses


Renewed Mandibular Reconstruction Process: The development of a universal fibula cutting guide and evaluation of a semi-automatic mandible reconstruction planning software

Vlaenderen, Angelique R.W. van (2020) Renewed Mandibular Reconstruction Process: The development of a universal fibula cutting guide and evaluation of a semi-automatic mandible reconstruction planning software.

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Abstract:The gold standard treatment for tumors that have invaded the mandible bone is surgical resection of the bone and reconstruction with free vascularized fibula grafts. Beforehand, a pre-operative plan is manually created and patient-specific three-dimensional (3D) printed cutting guides for both the fibula and mandible are developed. These guides allow accurate conversion of the plan to the surgical procedure. However, the process of developing a virtual plan and the patient specific guides is costly and time-consuming. In addition, the fixed plan and guides do not allow for adjustments intraoperatively. Both the lengthy time interval between planning and surgery and the inability to adjust the plan intraoperatively influences the surgical result negatively. To take on this problem, a new mandible resection process is proposed. Four things are needed: an automatic planning software, a universal fibula cutting guide, a universal mandible cutting guide, and universal reconstruction plates. A solution to the latter two was introduced already in previous works. In this study, solutions to the first two aspects are proposed. In this study, a universal fibula cutting guide is designed and developed. This guide enables adjustment of angle and length measurements intraoperatively. Although still a prototype, a phantom study was executed. The novel guide reached a mean (standard deviation (SD)) yaw and roll angle deviation of 1.1 (0.7)° and 0.9 (0.4)° respectively which was not inferior to the current guides that had a mean (SD) yaw and roll angle deviation of 2.2 (1.7)° and 1.0 (1.0)° respectively. The mean segment length deviations (SD) of the universal guide was 0.9 (0.3) mm and was significantly worse than the length deviations of the current cutting guides, 0.5 (0.2) mm. However, there is still a lot to improve on the guide, which could among other things improve the length accuracy. In addition, a first version of a semi-automatic planning software was submitted to us for evaluation. Comparison of 7 identically based manually made and automatically generated plans revealed the current version of the software does not reach acceptable plans yet. As judged by three head and neck surgeons, all manual plans were superior. Aside from a subjective evaluation, an objective evaluation method was introduced. Objective methods can be very useful in the development software to obtain the best possible plan. This evaluation method consisted of separate evaluations that could analyze the most important aspects of a plan. The bottom border, fibula surface coverage and mandibular angle positioning could be analyzed this way. The evaluation method of the outer border should be adjusted. However, by optimizing these evaluation methods and combining all aspects of evaluation into a rating system an overall conclusion about the acceptance of a plan may be reached.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine MSc (60033)
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