132 research outputs found
Različiti pristupi za kreiranje geometrijskih modela anatomske osi femura i tijela femura
In today\u27s medicine, especially in the field of orthopedic surgery, it is very important to use geometrically accurate and anatomically correct geometrical models of human bones for the pre-operative planning and implants creation. In order to create such models, two new methods for geometrical modeling were developed and presented in this paper. These methods enable creation of femur anatomical axis and femur shaft geometrical models, and they are: GCM (Gravity Center Method), and CPM (Curve Projection Method). Both methods enable creation of geometrical models which are based on data acquired from the medical imaging devices (CT, MRI, X-Ray). The basic difference between these two methods and all the others is in the manner of generating the points through which anatomical axis model (3D curve) passes or goes near. The applied methods are developed considering the natural shape and anatomical landmarks of the femur bone, as well as standard CAD techniques for geometrical modeling which are common in engineering.U današnjoj medicini, osobito u području ortopedske kirurgije vrlo je važno koristiti geometrijski točne i anatomski ispravne geometrijske modele ljudskih kostiju za pred-operativno planiranje i kreiranje implantata. Radi kreiranja takvih modela dvije nove metode geometrijskog modeliranja su razvijene i prezentirane u ovom radu. Ove metode omogućuju kreiranje geometrijskih modela anatomske osi femura i tijela femura i one su: GCM (eng. Gravity Center Method), i CPM (eng. Curve Projection Method). Obje metode omogućavaju kreiranje geometrijskih modela koji se temelje na podacima dobivenih od medicinskih uređaja (CT, MRI, X-Ray). Osnovna razlika između ove dvije metode u odnosu na sve ostale je u načinu generiranja točaka kroz koje anatomska os modela (3D krivulja) prolazi ili je u blizini. Primijenjene su tehnike koje su razvijene uzimajući u obzir prirodni oblik i anatomske značajke femura. kao i standardne CAD tehnike za geometrijsko modeliranje koje su uobičajene u inženjerstvu
USER DEFINED GEOMETRIC FEATURE FOR THE CREATION OF THE FEMORAL NECK ENVELOPING SURFACE
There is a growing demand for application of personalized bone implants (endoprostheses or macro-scaffolds, and fixators) which conform the anatomy of patient. Hence the need for a CAD procedure that enables fast and sufficiently accurate digital reconstruction of the traumatized bone geometry. Research presented in this paper addresses digital reconstruction of the femoral neck fracture. The results point out that User-Defined (geometric) Feature (UDF) concept is the most convenient to use in digital reconstruction of numerous variants of the same topology, such as in this kind of bone region. UDF, named FemoNeck, is developed to demonstrate capability of the chosen concept. Its geometry, controlled by a dozen of parameters, can be easily shaped according to anatomy of femoral neck region of the specific patient. That kind of CAD procedure should use minimally required set of geometric (anatomical) parameters, which can be easily captured from X-ray or Computed Tomography (CT) images. For the statistical analysis of geometry and UDF development we used CT scans of proximal femur of 24 Caucasian female and male adults. The validation of the proposed method was done by applying it for remodeling four femoral necks of four different proximal femurs and by comparing the geometrical congruency between the raw polygonal models gained directly from CT scan and reconstructed models
DESIGN OF 3D MODEL OF CUSTOMIZED ANATOMICALLY ADJUSTED IMPLANTS
Design and manufacturing of customized implants is a field that has been rapidly developing in recent years. This paper presents an originally developed method for designing a 3D model of customized anatomically adjusted implants. The method is based upon a CT scan of a bone fracture. A CT scan is used to generate a 3D bone model and a fracture model. Using these scans, an indicated location for placing the implant is recognized and the design of a 3D model of customized implants is made. With this method it is possible to design volumetric implants used for replacing a part of the bone or a plate type for fixation of a bone part. The sides of the implants, this one lying on the bone, are fully aligned with the anatomical shape of the bone surface which neighbors the fracture. The given model is designed for implants production utilizing any method, and it is ideal for 3D printing of implants
REVERSE ENGINEERING OF THE MITKOVIC TYPE INTERNAL FIXATOR FOR LATERAL TIBIAL PLATEAU
In orthopaedic surgery it is very important to use proper fixation techniques in the treatment of various medical conditions, i.e. bone fractures or other traumas. If an internal fixation method, such as plating, is required, it is possible to use Dynamic Compression Plates (DCP) or Locking Compression Plates (LCP) and their variants. For DCP implants it is important to match the patient's bone shape with the most possible accuracy, so that the most frequent implant bending is applied in the surgery. For LCP implants it is not so important to match the patient’s bone shape, but additional locking screw holes are required. To improve the geometrical accuracy and anatomical correctness of the shape of DCP and to improve the LCP geometric definition, new geometrical modelling methods for the Mitkovic type internal fixator for Lateral Tibia Plateau are developed and presented in this research. The presented results are quite promising; it can be concluded that these methods can be applied to the creation of geometrical models of internal fixator customized for the given patient or optimized for a group of patients with required geometrical accuracy and morphological correctness
GEOMETRICAL MODELS OF MANDIBLE FRACTURE AND PLATE IMPLANT
In the oral and maxillofacial surgery, there is a requirement to provide the best possible treatment for the patient with mandibular fractures. This treatment presumes application of reduction and fixation techniques for proper stabilization of the fracture site. The reduction of the bone fragments and their fixation is much better performed when geometry and morphology of the bone and osteofixation elements (e.g. plates) are properly defined. In this paper, a new healthcare procedure, which enables application of personalized plate implants for the fixation of the mandibular fractures, is presented. Geometrical models of mandible and plate implants, presented in this research, were created by means of the Method of Anatomical Features (MAF), which has been already applied to the creation of accurate geometrical models of various human bones, plates and fixators. By using such geometrically and anatomically accurate models, orthopedic and maxillofacial surgeons can better perform pre-operative tasks of simulating and planning the operation, as well as an intraoperative task of implanting the personalized plate into the patient body
Process planning for the rapid machining of custom bone implants
This thesis proposes a new process planning methodology for rapid machining of bone implants with customized surface characteristics. Bone implants are used in patients to replace voids in the fractured bones created during accident or trauma. Use of bone implants allow better fracture healing in the patients and restore the original bone strength. The manufacturing process used for creating bone implants in this thesis is highly automated CNC-RP invented at Rapid Manufacturing and Prototyping Lab (RMPL) at Iowa State University. CNC-RP is a 4th axis rapid machining process where the part is machined using cylindrical stock fixed between two opposing chucks. In addition to conventional 3 axes, the chucks provide 4th rotary axis that allows automated fixturing setups for machining the part. The process planning steps for CNC-RP therefore includes calculating minimum number of setup orientations required to create the part about the rotary axis. The algorithms developed in this thesis work towards calculating a minimum number of orientations required to create bone implant with their respective surface characteristics.
Usually bone implants may have up to 3 types of surfaces (articular/periosteal/fractured) with (high/medium/low) finish. Currently CNC-RP is capable of creating accurate bone implants from different clinically relevant materials with same surface finish on all of the implant surfaces. However in order to enhance the functionality of the bone implants in the biological environment, it is usually advisable to create implant surfaces with their respective characteristics. This can be achieved by using setup orientations that would generally isolate implant surfaces and machine them with individual finishes.
This thesis therefore focuses on developing process planning algorithms for calculating minimum number of orientations required to create customized implant surfaces and control related issues. The bone implants created using new customization algorithms would have enhanced functionality. This would reduce the fracture healing time for the patient and restore the original bone strength. The software package created using new algorithms will be termed as CNC-RPbio throughout in this thesis
The three main tasks in this thesis are a) calculating setup orientations in a specific sequence for implant surfaces b) Algorithms for calculating a minimum number of setup orientations to create implant surfaces c) Machining operation sequence. These three research tasks are explained in details in chapter 4 of this thesis.
The layout of this thesis is as follows. Chapter 1 provides introduction, background and motivation to the research in this thesis. Chapter 2 provides a literature review explaining different researches conducted to study the effects of different surface finish on the bone implants on their functionality. It also presents different non-traditional and RP techniques used to create bone implant geometries with customized surfaces, their advantages and limitations. Chapter 3 gives the overview of process planning algorithms used for CNC-RP and those needed for CNC-RPbio. Chapter 4 is the main chapter of the thesis including process planning algorithms for rapid machining of bone implants with customized surfaces using CNC-RP in details, while Chapter 5 provides Conclusions and Future work
REVERSE ENGINEERING OF THE HUMAN FIBULA BY USING METHOD OF ANATOMICAL FEATURES
This paper describes reverse engineering (RE) of human fibula, on right male bone, using the method of anatomical features (MAF) with the aim to obtain 3D surface model. The first step in the process of reverse engineering was CT scanning and digitalization of data. CT data were obtained with Toshiba MSCT scanner Aquillion 64 and saved in DICOM format. This data were subjected to further processing and imported in Computer Aided Design (CAD) program as STL file. The process continues in CAD program with identification and determination of Referential Geometrical Entities (RGEs) which are crucial for RE process. These RGEs are the basis for definition of axis and planes of intersection. Intersecting polygonal model of fibula bone on upper and lower extremities and the body with these planes gives as result set of curves, which were used for points determination on them. Through these points splines were pulled, and with loft function surface models of extremities and the body of fibula bone is built. Joining and merging of these models leaded to 3D shape model of fibula bone. Accuracy of the model is confirmed by conducting distance and deviation analysis. Model is suitable for rapid prototyping, reconstruction missing parts of fibula bone, orthopedic training and simulation
In Silico Optimization of Femoral Fixator Position and Configuration by Parametric CAD Model
Structural analysis, based on the finite element method, and structural optimization, can help surgery planning or decrease the probability of fixator failure during bone healing. Structural optimization implies the creation of many finite element model instances, usually built using a computer-aided design (CAD) model of the bone-fixator assembly. The three most important features of such CAD models are: parameterization, robustness and bidirectional associativity with finite elements (FE) models. Their significance increases with the increase in the complexity of the modeled fixator. The aim of this study was to define an automated procedure for the configuration and placement of fixators used in the treatment of long bone fractures. Automated and robust positioning of the selfdynamisable internal fixator on the femur was achieved and sensitivity analysis of fixator stress on the change of major design parameters was performed. The application of the proposed methodology is considered to be beneficial in the preparation of CAD models for automated structural optimization procedures used in long bone fixation
TOWARDS PATIENT SPECIFIC PLATE IMPLANTS FOR THE HUMAN LONG BONES: A DISTAL HUMERUS EXAMPLE
Plate implants are the most used internal fixators for the surgical treatments of the bone fractures. In clinical cases where there is a requirement to use reconstruction plates, and/or to stabilize the fracture, adaptation of plate shape (e.g. bending) to the patient anatomy is required, and it is usually done during the surgery. In order to eliminate the need for intra-operative bending of plates, precontoured plates can be used. These are patient specific implants whose shape and geometry is adapted to the anatomy and morphology of the specific patient. In order to create a patient specific 3D model of the plate implant, the bone model acquired through medical imaging (e.g. Computed Tomography - CT) is commonly used. By the application of various CAD techniques, the volume model of specific plate implant can be created, and used for the production of the plate, by conventional or additive manufacturing technologies. In this paper the authors present a new approach to the creation of a 3D parametric model of the patient specific plate implant for distal humerus. By using such model the surgeon can perform preoperative planning and adapt shape of plate to the specific patient before the surgery, and in this way he can improve pre, intra and post-operative processes
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