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

Designing of Patient-Specific Implant by Using Subdivision Surface Shaped on Parametrized Cloud of Points

Patient-specific orthopaedic implant application improves the recovery of the fractured bone in comparison to the conventional implant of standardized shape and size. The main challenge regarding creation of this kind of implant is its design process because the conventional modelling techniques based on using NURBS for shaping the unique bio-forms take a lot of time and effort. The research found out that the application of combination of two design techniques may accelerate the whole design process for more than 60% comparing to the conventional approach while improving the geometric congruency of the implant and the bone. The first is about digital reconstruction of the bone geometry by the polygonization of the synthetic cloud of points built on radiographic images of the injured bone. The second is applying semi-automated surface subdivision modelling technique for shaping the implant. The research was done for the case of designing the internal fixator of Mitkovic type aimed for lateral tibial plateau fracture

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

Analysis of femoral trochanters morphology based on geometrical model

210-216This study presents morphological analysis of 20 scans of femur samples from European (Serbian) adults from trochanteric region based on the customized computer aided reverse modeling procedure. Results indicated that trochanteric region is a separate morphological unit of proximal femur, named trochanteric wedge or canoe. This new perceiving of trochanteric region seems to provide a better understanding of trochanteric wedge volume and, therefore, better trochanter fractures treatment, operation planning, implant and endoprothesis design and selection. Also, it brings a new light to anatomy of proximal femur, its biomechanics and ossification

Reverse Modelling of Human Long Bones Using T-Splines - Case of Tibia

Creating a sufficiently accurate digital model of human bone geometry for a specific patient is the starting point for personalized orthopaedic surgical treatment. Such geometrical model of a particular human bone serves as a template for designing personalized bone implant, which can be an endoprostheses, fixator plate or even scaffold. Due to that role, the geometry of a human bone model has to be reusable and modifiable. Otherwise, design of the corresponding personalized implant for a particular human bone is a very difficult task. Modern reverse modelling techniques have greatly accelerated the creation of a bone geometric model. The prevailing modern approach is based on the use of non-uniform rational B-splines. However, recent research shows that the very complex topology of bio-shapes, such as human bones, can be reconstructed more easily using T-Splines. The presented approach of using T-splines in a modelling process allows creation of a bone model with important advantages regarding quality, flexibility and geometric accuracy. The process of reverse modelling starts from the cloud of points gained through computer-tomography images and uses selected referential geometric, i.e. anatomic entities as guiding elements in digital reconstruction of the particular bone geometry