Reverzni inženjering dugih kostiju čoveka zasnovan na morfometrijskim parametrima

Abstract

Development of new and improvement of existent methods of creating geometrical models of human bones is a continual process in modern medicine. Basically, most methods use medical images obtained from various devices (medical scanners) as input data. These devices can be classified into those which enable forming of 2D images of scanned object, such as X-ray or 2D ultrasound, and those which enable creation of 3D images (volumetric models), such as Computed Tomography (CT) or Magnetic Resonance Imaging (MRI). Different types of processing can be performed on obtained data, resulting in adequate geometrical human bone models which can be used for various purposes, including: preparation and simulation of orthopedic interventions, students’ and doctor's training to perform orthopedic interventions, production of osteo-fixational material, analysis of stress and strain of assembly of bones and implants. Problem description: While creating bone models based on data acquired from medical scanners, two distinct cases which prevent their proper forming can be isolated. Both cases are related to incomplete data of morphology and geometry of human bone, but with different reasons for data deficiency. In the first case, volumetric scanners are not available, or cannot be used for specific reasons, e.g.: patient must not be treated with high level radiation, faulty device, institution doesn’t possess adequate scanner, patients with metal implants, and such. In these cases, devices such as X-ray or, less often, ultrasound are used. The outcome of this process is one or eventually two 2D images (if the device is digital), or film (if analog X-ray apparatus is used). Complete 3D bone visualization can be difficultly accomplished on the basis of 2D data, so methods which enable creation of 3D geometrical bone models based on one or more 2D images are developed today. The second case refers to inability to create an image of complete bone. This case isn’t connected to acquisition of bone data from medical images (although it can be), but it is mostly conditioned by health state of the patient. Example of these cases include: multiple bone fractures, osteoporosis, other diverse acute and chronic diseases and such. Surgeons aren’t able to properly plan surgical procedures based on a partial image; consequently, certain surgical decisions have to be made during the very surgery. Goal of research: The main goal of the dissertation has been to form a method which would enable creation of complete geometrical bone model based on both complete and incomplete entrance data of patients’ bones (regardless the cause of data deficiency), and which would also 10 greatly contribute to the process of preparation, planning and performance of orthopedic surgeries. Research Subject: Research subject of the dissertation are methods of reverse engineering which can be applied to obtain 3D geometrical models of the human long bones directly from radiology images, whether the data is complete or incomplete. Research result: Method of Anatomical Feature – MAF is formed as the result of applied research whose application enables realization of the goal of research. MAF introduce a new approach to describe geometrical entities of human bones, based on anatomical landmarks/ guide lines. MAF enables creation of 3D geometrical models and parametric point bone models. The main goal of application of MAF is to create 3D geometrical models (of whole bones, as well as of the missing bone parts) of high geometrical accuracy and anatomical correctness, even in cases when the bone data is incomplete. Based on afore mentioned, we can conclude that MAF is a universal method to create different geometrical models of bones or bones’ parts, which means that an adequate model can be created depending on the current situation (need, case). Verification and application of research results: Various types of geometrical models (polygonal, surface, volumetric, parametric) of certain bones of human body have been created to verify MAF. All created geometrical models have satisfied necessary accuracy in geometrical and anatomical terms, which is defined in scientific literature. This paper provides examples of created geometrical models of femur and tibia bones; however, more geometrical models of other bones (fibula, humerus, mandible, etc.) have been created during this research. Nevertheless, MAF has been, both directly and indirectly (geometrical models of bones created with MAF have been used) applied for other purposes. These are characteristic cases which can appear in clinical practice, some of which are: case of creation of customized sternum implant, use of MAF to create parametric model of internal fixator by Mitkovic, application of Finite Element Method (FEM) to analyze stress and strain of femur bone and internal fixator by Mitkovic, use in application prototype for the simulation of orthopedic surgeries, etc. Conclusion: Based on everything stated above, conclusion follows that research results presented in this paper display a significant scientific contribution which greatly contributes to improvement of methods used in reverse engineering and geometrical modeling of long bones of skeletal-joint system in humans.