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Computer aided method for 3D assessment of the lower limb alignment for orthopedic surgery planning

January, 1 2017 2 minute read


Tomás Augusto Esteves Ferreira


Hugo Alexandre Ferreira & Jalil Jalal


Alinhamento do Membro Inferior, Avaliação 3D do Alinhamento, Software Planeamento Pré-Cirúrgico & Planeamento de Correção de Deformações

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The lower limbs are responsible for supporting the body and are essential for several tasks such as standing, walking and running. Sometimes, and due to various reasons, defects or deformities can be found on the lower limbs and this has an impact on a person’s quality-of-life. One characteristic of the structure of the lower limb that is affected by these deformities is its alignment, i.e. the relative positions of the bones and joints that it includes. Thanks to the evolution of modern medicine, fixing these deformities is now a common practice in the orthopedics' surgical field. Before any corrective surgery and its respective planning, the deformity needs to be properly analyzed, which is accomplished by the assessment of the alignment of the whole lower limb. Currently, in clinical setting, this assessment is carried out manually in the two-dimensional space, normally using wholeleg X-ray images of the anatomical frontal plane, but complex deformities can not be assessed properly in a 2D image. In a desire to create an automatic computer-based method for the preoperative planning of deformity correction and knee surgery, a project consisting of developing a new software for assessing the lower limb alignment based on 3D models was proposed. The project was comprised of four stages: In the first stage, 3D models of different patients’ lower limbs were generated using both segmentation and 3D rendering software, and it was ensured that these models could be generated by any user without significant variability/error in the final outcome; In the second stage, the exact angles and measures needed for a proper assessment were defined, as well as the anatomic landmarks required to calculate them that should then be found by the software; During the third stage, the software development took place, from which resulted a program that uses the generated 3D models and, in the most automatic way possible and with an easy-to-use interface, returns all the needed angles and measures; The final stage of the project was to ensure that the program is reliable and consistent in its results in both intraobserver and interobserver domain, and that it composes an improvement when compared with the manual procedure, while also ensuring that the results obtained by using the program match those obtained manually. A lot can still be done and improved regarding the developed software and the ultimate goal of fully developing a preoperative planning method, but, so far, the 3D alignment assessment that results from the program has been considered to perform its task properly and in an improved way when compared to the traditional technique, even though some limitations can be observed.

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