University of Twente Student Theses


Improving 3D virtual surgical planning and guided corrective osteotomies

Tabernée Heijtmeijer, SJ.C. (2022) Improving 3D virtual surgical planning and guided corrective osteotomies.

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Embargo date:October 2026
Abstract:Background: Corrective osteotomies are frequently performed to restore bone deviations and function of the affected limb and to decrease the progression of osteoarthritis by reducing load on the joint induced by the pathoanatomy. However, surgery for multi-planar corrections is challenging to perform with the current gold-standard “free hand” method. Patient-specific instrumentation (PSI) such as drilling and cutting guides have been promising adjunct to perform accurate corrections with potentially superior clinical outcome. For a sufficient surgical outcome, a certain positioning accuracy of PSI is necessary, but the current accuracy is unknown, as are the consequences of a deviation intraoperatively. Nor is there a gold standard for the postoperative quantification of corrective osteotomies or for PSI design. It is necessary to know the exact surgical result to be able to improve the virtual surgical planning and PSI. Objectives: 1) To determine the current intraoperative positioning accuracy of surgical guides for corrective osteotomy for long bones. 2) To determine the current accuracy and inter- and intraobserver variability of a 3D postoperative surgical outcome analysis for corrective osteotomies. 3) Propose a standardised quantitative 3D CT methodology for a postoperative surgical outcome analysis after 3D planned guided corrective osteotomies performed and evaluate the accuracy and observer variability of the proposed methodology compared to the current standard. 4) Compare the positioning accuracy of new curvature-based guide design to the accuracy of the current standard design. 5) To define the positioning accuracy of surgical guides required for sufficient clinical outcome and determine whether the current transfer is sufficiently accurate, and if necessary, where there is room for improvement Methods: 1) Retrospectively, guide positioning was determined for 8 corrective osteotomies by 5 observers by assessment of the realised osteotomy plane. 2) The current accuracy and variability of the methodology was evaluated by assessment of the individual analysis of 5 observers of the surgical outcome of a guided high tibial osteotomy 3) Based on the results and in accordance with the observers a methodology was proposed and evaluated on accuracy and observer variability for a similar patient case. 4) The positioning accuracy of two novel designs based on a curvature analysis of the bone was evaluated compared to the current standard with a cadaver study 5) By compiling the results, this thesis attempts to clarify and compare the necessary positioning accuracy with the current accuracy, as well as present methods to improve the accuracy of the positioning. Conclusion: This Master thesis resulted in further insight into the current intraoperative positioning accuracy of patient-specific guides. It showed the poor performance of the current methodology to assess surgical outcome and proposed an excellent standardised method for the postoperative objective evaluation of surgical performance. Furthermore, two new guide designs were developed and assessed, which have led to qualitative improvements for current standard guide design.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine MSc (60033)
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