Novel approach for critical bone defect repair, A

2022 Summer.Includes bibliographical references.Critical bone defects are defined as defects that will not naturally heal over a patient's lifetime, even with surgical stabilization. When these occur in the long bones of the axial skeleton (secondary to trauma, tumor resection, etc.), limb-sparing surgery can be performed to avoid amputation of the limb. This procedure typically involves the installation of a steel locking plate over the defect, along with an endoprosthesis or allograft to fill the void of resected bone. Much progress has been made in the natural bone regeneration using tissue engineering (TE) scaffolds in place of these grafts. Porous hydroxyapatite (HAP) is a well-established bone TE scaffold biomaterial but lacks sufficient mechanical strength when fabricated at porosities shown to best induce osteogenesis. To remedy this, polymers such as polycaprolactone (PCL) are often mixed with HAP to fabricate scaffolds with increase load-bearing capacity. However, the addition of PCL makes the scaffold less osteogenic and dramatically slows the degradation rate of the scaffold. This translates into reduced new bone volume where the PCL cannot be remodeled as new bone is formed. This project involves a pilot clinical trial of a novel method that augments the gold-standard limb-sparing procedure by implanting a 3D printed endoprosthetic "sleeve" device that attaches to the locking fixation plate and contains and protects the brittle HAp scaffold. The PCL sleeve alleviates the dependency on scaffold strength which enables use of the most osteogenic possible biomaterials at ideal porosities to maximize the rate and density of new bone formation. The purpose of the study is to clinically validate the construct design and surgical procedure. Thus far, pilot limb-sparing surgeries have been performed on 4 client-owned dogs, in which sleeve-scaffold devices were installed in the critical defects caused by the removal of osteosarcomas in distal epiphyseal radii. Recombinant human bone morphogenic protein-2 (rhBMP-2) was added to the scaffolds to further encourage osteogenesis. Mechanical tests were performed on both the sleeves alone and the full construct installed in canine cadaver limbs. Results from this testing demonstrate the sleeve's ability to prevent mechanical failure of the HAp scaffolds. Similarly, no scaffold failure has been observed in clinical trial patients, with some having the device installed for greater than 24 weeks. Additionally, pressureometry and gait analysis confirmed excellent return of limb function in these animals. However, to date, no new bone formation has been observed within the scaffold devices, which has likely been inhibited by anti-cancer treatment. Regardless, results from ex vivo testing and the clinical trial validate the construct design and the viability of our novel method for protecting and maintaining brittle bone tissue engineering scaffolds, while aiding in restoration of normal limb function

Additive Manufacturing of Ceramics. Printing Beyond the Binder

This research project focuses on the production of ceramics via Additive Manufacturing (AM) techniques, with particular focus on extrusion-based technologies. The main advantage of AM is the ability to produce cellular structures with high complexity and controlled porosity, allowing to manufacture light but efficient stretch-dominated structures. The inspiration comes from nature: bone architectures are a great example, consisting of thin, solid skins attached to highly porous, cellular cores. Very few commercially available AM systems are suited for ceramic materials, and most of them use ceramic powders as feedstock. Residual pores and cracks are very hard to avoid and result in low strength, poor reliability and loss of unique material properties such as glass optical transparency. AM technologies employing polymers are at a much more advanced stage of development. The goal has been to exploit such advances and to provide alternatives to the ceramic powder-binder approaches. Three different material families were explored: preceramic polymers, geopolymers, and glass. The same preceramic polymer, a commercial polysilsesquioxane, was employed as a non sacrificial, reactive binder to develop inks for stereolithography (SL) and direct ink writing (DIW). The first technology allowed for production of dense, crack-free SiOC micro-components with strut size down to ~200 μm and optimal surface quality. No shape limitations were experienced, but porous structures or small dense parts are the best options in order to avoid residual pores and cracks. The second approach was employed for the fabrication of complex biosilicate scaffolds for tissue engineering with a rod diameter of 350 µm and unsupported struts. The preceramic polymer had the double role of source of silica and rheology modifier. Ceramic matrix composites (CMCs) were also fabricated; the preceramic polymer developed the ceramic matrix (SiOC) upon pyrolysis in inert atmosphere, whereas reinforcement was given by chopped carbon fibers. Geopolymer components with controlled porosity were designed and produced first by negative replica of PLA sacrificial templates and then by DIW. Highly porous ceramic components with features of ~800 μm and unsupported parts with very limited sagging were produced with the latter approach. A novel extrusion-based AM approach was finally developed for the production of objects starting from molten glass. The system processed glass from the molten state to annealed components of complex, digitally designed forms. Objects possessing draft angles and tight radii were fabricated. Within the design space it was possible to print with high precision and accuracy; parts showed a strong adhesion between layers, and high transparency through the layers

Advanced Applications of Rapid Prototyping Technology in Modern Engineering

Rapid prototyping (RP) technology has been widely known and appreciated due to its flexible and customized manufacturing capabilities. The widely studied RP techniques include stereolithography apparatus (SLA), selective laser sintering (SLS), three-dimensional printing (3DP), fused deposition modeling (FDM), 3D plotting, solid ground curing (SGC), multiphase jet solidification (MJS), laminated object manufacturing (LOM). Different techniques are associated with different materials and/or processing principles and thus are devoted to specific applications. RP technology has no longer been only for prototype building rather has been extended for real industrial manufacturing solutions. Today, the RP technology has contributed to almost all engineering areas that include mechanical, materials, industrial, aerospace, electrical and most recently biomedical engineering. This book aims to present the advanced development of RP technologies in various engineering areas as the solutions to the real world engineering problems

A virtual environment for the modelling, simulation and manufacturing of orthopaedic devices

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The objective of this work is to investigate whether the game physics based modelling is accurate enough to be used in modelling the motion of the human body, in particular musculoskeletal motion. Hitherto, the implementation of game physics in the medical field focused only on anatomical representation for education and training purposes. Introducing gaming platforms and physics engines into orthopaedics applications will help to overcome several difficulties encountered in the modelling of articular joints. Implementing a physics engine (PhysX), which is mainly designed for video games, handles intensive computations in optimized ways at an interactive speed. In this study, the capabilities of the physics engine (PhysX) and gaming platform for modelling and simulating articular joints are evaluated. First, a preliminary validation is carried out for mechanical systems with analytical solutions, before constructing the musculoskeletal model to evaluate the consistency of gaming platforms. The developed musculoskeletal model deals with the human joint as an unconstrained system with 6 DOF which is not available with other joint modeller. The model articulation is driven by contact surfaces and the stiffness of surrounding tissues. A number of contributions, such as contact modelling and muscle wrapping, have been made in this research to overcome some existing challenges in joint modelling. Using muscle segmentation, the proposed technique effectively handles the problem of muscle wrapping, a major concern for many; thus the shortest path and line of action are no longer problematic. Collision behaviour has also shown a stable response for colliding as well as resting objects, provided that it is based on the principles of surface properties and the conservation of linear and angular momentums. The precision of collision detection and response are within an acceptable tolerance controllable by varying the mesh density. An image based analysis system is developed in this thesis, mainly in order to validate the proposed physics based modelling solution. This minimally invasive method is based on the analysis of marker positions located at bony positions with minimal skin movement. The image based system overcomes several challenges associated with the currently existing methods, such as inaccuracy, complication, impracticability and cost. The analysis part of this research has considered the elbow joint as a case study to investigate and validate the proposed physics based model. Beside the interactive 3D simulation, the obtained results are validated by comparing them with the image based system developed within the current research to investigate joint kinematics and laxity and also with published material, MJM and results from experiments performed at the Brunel Orthopaedic Research and Learning Centre. The proposed modelling shows the advantageous speed, reliability and flexibility of the proposed model. It is shown that the gaming platform and physics engine provide a viable solution to human musculoskeletal modelling. Finally, this thesis considers an extended implementation of the proposed platform for testing and assessing the design of custom-made implants, to enhance joint performance. The developed simulation software is expected to give indicative results as well as testing different types of prosthetic implant. Design parameterization and sensitivity analysis for geometrical features are discussed. Thus, an integrated environment is proposed to link the real-time simulation software with a manufacturing environment so as to assist the production of patient specific implants by rapid manufacturing

The characteristics of the CAT to CAD to rapid prototyping system

ThesisComputer Aided Design (CAD), Rapid Prototyping (RP) and Computer Aided Tomography (CAT) technologies were researched. The project entails a unique combination of the abovementioned technologies, which had to be mastered by the author, on local and international terms. Nine software packages were evaluated to determine the modus operandi, required input and final output results. Fifty Rapid Prototyping systems were investigated to determine the strong and weak areas of the various systems, which showed that prototype materials, machine cost and growing time play an essential role. Thirty Reverse Engineering systems were also researched. Six different RE methods were recorded with several commercial systems available. Nineteen case studies were completed by using several different Computer Aided Tomography (CAT) and Magnetic Resonance Imaging (MRI) centers. Each scanning centre has different apparatus and is discussed in detail in the various case studies. The focus of this project is the data transfer of two dimensional CAT scanning data to threedimensional prototypes by using Reverse Engineering (RE) and Rapid Prototyping (RP). It is therefore of cardinal importance that one is familiar and understands the various fields of interest namely Reverse Engineering, Computer Aided Tomography and Rapid Prototyping. Each of these fields will be discussed in detail, with the latest developments in these fields covered as well. Case studies and research performed in the medical field should gain the medical industry's confidence. Constant marketing and publications will ensure that the technology is applied and transferred to the industry. Commercialisation of the technology is of utmost importanc

Rechnergestützte Planung und Rekonstruktion für individuelle Langzeit-Knochenimplantate am Beispiel des Unterkiefers

Die vorliegende Arbeit befasst sich mit der Entwicklung und Umsetzung von Methoden und Werkzeugen zur Bereitstellung von Modellen und Randbedingungen für die Konstruktion individueller Langzeit-Knochenimplantate (Konstruktionsvorbereitung). Grundlage dabei ist, dass die Planung aus medizinischer Sicht z.B. durch einen Chirurgen und die Konstruktion unter technischen Aspekten z.B. durch einen Konstrukteur getrennt erfolgt. Hierfür wird ein erarbeitetes Planungskonzept vorgestellt, welches sowohl die geplanten geometrischen Merkmale, als auch weiterführende Metadaten beinhaltet (Randbedingungen). Die Übergabe dieser Planungsdaten an die Konstruktion erfolgt über eine dafür entworfene Formatbeschreibung im Kontext der Schnittstelle zwischen Mediziner und Ingenieur. Weiterführend wird die Notwendigkeit von speziellen Funktionen für die Konstruktion von individuellen Implantaten in der Arbeitsumgebung des Konstrukteurs (z.B. Modelliersystem – CAD) am Beispiel der konturlinienbasierten Modellrekonstruktion erörtert. Die gesamtheitliche Basis bildet eine durchgängig digitale Prozesskette zur Datenaufbereitung, Konstruktion und Fertigung. Die Anwendbarkeit der Methoden und zweier umgesetzter Demonstratoren wurde innerhalb eines interdisziplinär angelegten Projektes am realen Patientenfall bestätigt

Biomedical Engineering

Biomedical engineering is currently relatively wide scientific area which has been constantly bringing innovations with an objective to support and improve all areas of medicine such as therapy, diagnostics and rehabilitation. It holds a strong position also in natural and biological sciences. In the terms of application, biomedical engineering is present at almost all technical universities where some of them are targeted for the research and development in this area. The presented book brings chosen outputs and results of research and development tasks, often supported by important world or European framework programs or grant agencies. The knowledge and findings from the area of biomaterials, bioelectronics, bioinformatics, biomedical devices and tools or computer support in the processes of diagnostics and therapy are defined in a way that they bring both basic information to a reader and also specific outputs with a possible further use in research and development

Libro de actas. XXXV Congreso Anual de la Sociedad Española de Ingeniería Biomédica

596 p.CASEIB2017 vuelve a ser el foro de referencia a nivel nacional para el intercambio científico de conocimiento, experiencias y promoción de la I D i en Ingeniería Biomédica. Un punto de encuentro de científicos, profesionales de la industria, ingenieros biomédicos y profesionales clínicos interesados en las últimas novedades en investigación, educación y aplicación industrial y clínica de la ingeniería biomédica. En la presente edición, más de 160 trabajos de alto nivel científico serán presentados en áreas relevantes de la ingeniería biomédica, tales como: procesado de señal e imagen, instrumentación biomédica, telemedicina, modelado de sistemas biomédicos, sistemas inteligentes y sensores, robótica, planificación y simulación quirúrgica, biofotónica y biomateriales. Cabe destacar las sesiones dedicadas a la competición por el Premio José María Ferrero Corral, y la sesión de competición de alumnos de Grado en Ingeniería biomédica, que persiguen fomentar la participación de jóvenes estudiantes e investigadores