Methods for medical applications

Synthetic scaffolds for tissue engineering coupled to stem cells represent a promising approach aiming to promote the regeneration of large defects of damaged tissues or organs. Magnetic nanocomposites formed by a biodegradable poly(caprolactone) (PCL) matrix and superparamagnetic iron doped hydroxyapatite (FeHA) nanoparticles at different PCL/FeHA compositions have been successfully prototyped, layer on layer, through 3D bioplotting. Magnetic measurements, mechanical testing, and imaging were carried out to calibrate both model and technological processing in the magnetized scaffold prototyping. An amount of 10% w/w of magnetic FeHA nanoparticles represents a reinforcement for PCL matrix, however, a reduction of strain at failure is also observed. Energy loss (absorption) measurements under a radio-frequency applied magnetic field were performed in the resulting magnetic scaffolds and very promising heating properties were observed, making them very useful for potential biomedical applications. © 2011 American Institute of Physics.

Low back pain, a common cause of disability in individuals - especially between 20 and 50 years old - with enormous socioeconomic consequences, may be strongly associated with the degeneration of the intervertebral disc (IVD). The traditional IVD treatments, such as spinal fusion, even though they provide amelioration of the pain, present different drawbacks; consequently there is a lot of research interest in replacing the damaged disc with an artificial one. In this chapter, after an introductory part on IVD and the pathologies and treatment related to it, an overview of the IVD traditional prostheses is given, followed by the presentation of new hydrogels-based prostheses designed according to a biomimetic approach. Finally, the hydrogels-based systems aimed to replace the nucleus pulposus (NP) and to act as scaffolds to carry cells to engineer the IVD tissues are described.

Keywords: Hydrogels , Intervertebral disc prostheses , Nucleus pulposus , Tissue engineering

Neurodegenerative disorders are expected to strike social and health care systems of developed countries heavily in the coming decades. Alzheimer's and Parkinson's diseases (AD/PD) are the most prevalent neurodegenerative pathologies, and currently their available therapy is only symptomatic. However, innovative potential drugs are actively under development, though their efficacy is sometimes limited by poor brain bioavailability and/or sustained peripheral degradation. To partly overcome these constraints, the development of drug delivery devices made by biocompatible and easily administrable materials might be a great adjuvant. In particular, materials science can provide a powerful tool to design hydrogels and nanoparticles as basic components of more complex nanocomposites that might ameliorate drug or cell delivery in AD/PD. This kind of approach is particularly promising for intranasal delivery, which might increase brain targeting of neuroprotective molecules or proteins. Here we review these issues, with a focus on nanoparticles as nanocomponents able to carry and tune drug release in the central nervous system, without ignoring warnings concerning their potential toxicity. © 2011 Wichtig Editore.

Keywords: Alzheimer's disease , Hydrogels , Intranasal delivery , Nanocomposites , Nanoparticles , Nanotoxicity , Parkinson's disease

Mini-invasive surgery deserves increasing attention to lower post-operative stays in hospitals and to lessen fall-off complications. This new book is devoted to surgical robotics, with a focus on technology and design issues of the remote-mode operation assistants. The investigation leads to define the technical characteristics of a CRHA, co-robotic handling appliance, to be purposely developed, to support the duty-split approach surgical planner. © 2010 by Nova Science Publishers, Inc. All rights reserved.

Assessment of facial soft tissues could be implemented using only anatomical landmarks. These points are so significant in the medical context because are able to provide significant information about the human face morphology and dimensions. At present their detection and location is made by expert physicians using palpation. Even if this procedure normally provides reliable information, the reliability of the results is proportional to the expertise of the physician. Considering that at present many physicians are beginning to use 3D scanners that provide three-dimensional data of the human face, it is possible to implement a robust and repeatable methodology that supports the physician's diagnosis. To reach this goal it is necessary to implement a methodology based on geometrical codification of landmarks and which mathematically formalizes the physician's visual and palpation analyses of the real patient. © 2010 Springer Science+Business Media, LLC and International Society of Aesthetic Plastic Surgery.

Keywords: 3D scanners , Automatic detection , Human face , Soft tissues landmarks

In this work a new method for symmetry line recognition, from 3D scanned data of a subject's back, is presented. The new method is validated by comparison with traditional techniques based on cutaneous marking. For this purpose, the upright standing and sitting postures of a sample of 75 subjects, who usually perform different sports activities, are analysed. Error in symmetry line detection is measured as the distance between the estimated symmetry line and the position of the markers. The proposed method is compared with another one described in literature which has been validated in clinical field. Results are analysed and critically discussed. © 2010 Taylor & Francis Group, LLC.

Keywords: Back shape analysis , Posture prediction , Symmetry line

This paper presents a new design framework to configure lower limb prostheses, both transfemoral and transtibial, where the key elements are the patient digital avatar and the domain knowledge. The technician is supported during the design process by the knowledge acquired from analysis of the traditional process and represented in the framework. The last one integrates virtual prototyping tools and knowledge management techniques. A specific software tool, named Socket Modelling Assistant, has been developed to design the socket, the custom-fit component of the prosthesis. A commercial CAD system is used to model the standard components (e.g., knee, foot and tubes) and to create the final assembly. Patient avatar and his/her data (e.g., anthropometric and physiological parameters) are the backbone of the whole product design process. They guide both the selection of standard components and the modelling of the socket digital model. Copyright © 2010 by ASME.

In this paper, we propose a knowledge-based approach to design lower limb prostheses; in particular, we focus on the 3D modelling of the socket, the most critical component. First, the architecture of a dedicated knowledge based engineering framework is described, detailing features of the main design steps. Then, the paper discusses the acquisition and formalization of the knowledge related both to the prosthesis manufacturing process and to the considered component. Finally, we present a computer-aided module, named Socket Modelling Assistant-SMA, to design the socket; it is a virtual laboratory where the socket virtual prototype is generated directly on the digital model of patient's residual limb. It guides and supports the designer during each step in an automatic and/or semi-automatic way applying design rules and procedures. The guided modelling steps and available tools are described. Work in progress and future developments conclude the paper. © Organizing Committee of TMCE 2010 Symposium.

Keywords: 3d socket modelling , Knowledge-based design , Lower limb prosthesis , Virtual prototyping

This paper presents a 3D CAD system to design sockets of lower limb prostheses, both transfemoral and transtibial. The proposed system, named Virtual Socket Laboratory, can be seen as a virtual laboratory where the user has at her/his disposal virtual tools that permit to emulate the procedures applied by orthopaedic technicians during the traditional socket manufacturing. The module is centred on the digital model of the patient and is based on the specific domain knowledge to guide the user during socket modelling suggesting the most appropriate design rules and procedures. First, main steps of the new design-modelling process and system functionalities are presented. Then, for each step, procedures carried during the traditional process, how they are executed with the new module and tools specifically developed are described. © 2010 CAD Solutions, LLC.

Keywords: 3d socket modelling , Artificial prosthesis design , Knowledge-based system

This paper presents a new approach to design lower limb prosthesis focusing the attention on geometrical model issues. The new design approach has been developed within national and international research projects and, at present, "ad hoc" tools to carry out specific tasks are under development. Within this context, an important role is played by product and process knowledge and by specific CAD tools to design the most critical component, the socket. The paper discusses acquisition and formalisation of the knowledge related to the prosthesis design, with particular attention to the socket, and presents main features of a CAD tool specifically intended for this highly customised component. Copyright © 2009 by ASME.

This paper presents a new 3D design paradigmfor the development of specific custom-fit products, such as the soft socket of prostheses for lower limb amputees. It is centered on the digitalmodel of the human body and, contrarily to the traditional process almost manually based, it considers the integration of methods and tools coming from different research and application fields: Reverse Engineering, Medical Imaging, Virtual Prototyping, Physics-based Simulation, and Rapid Prototyping. The paper describes the techniques adopted to acquire and create the digital model of the residual limb, the procedure to generate the socket model, the strategy developed for the functional simulation of the socket-stump interaction and, finally, the realization of the physical prototype. Each design step is described with the related problems and the obtained results. Both trans-tibial and trans-femoral amputees have been considered; however, for now the complete process has been validated for trans-tibial prostheses. Major outcomes of the proposed approach stand in a better quality of the final product, in a shorter involvement of the amputee implying a lower psychological impact, in a limited use of physical prototypes, and in a shorter development time. Moreover, the resulting paradigm answers to the Collaborative Engineering guidelines by optimizing the interaction between different domains and enhancing their contributions in a homogeneous development framework. © 2010 Elsevier B.V. All rights reserved.

Keywords: Custom-fit products , Human-centric soft product design , Physics-based modeling for soft products , Prosthesis development process

Complex periodontal surgeries can be performed using preoperative planning based on CT or MRI data that permit a 3D reconstruction of the patient bone anatomy. This allows a more accurate assessment of the surgical difficulties by the surgeon. The precise placement of dental implants is a crucial step to optimize both prosthetic considerations and functional aspects and the use of physical guiding systems has been recognized as a fundamental tool to control their positions and angulations. The weak point of the procedure relies on the accuracy of transferring CT planning information to the surgical field by means of custom-made stereolithographic guides. This paper concerns the study of an innovative methodology for the monitoring of the loss in the clinical accuracy through the various steps concurring in this transfer. The procedure is based on the integration of an optical scanner, with a structured coded light approach, within the CT scan based preoperative planning process. The higher resolution and accuracy, compared to CT scanning systems, has allowed for the use of the optical scanner as a standard to evaluate the precision of CT data and fabrication processes of the guiding templates. A clinical case if finally presented and discussed. © 2010 Taylor & Francis Group.

This study represents a preliminary activity for the biomechanical numerical modeling aimed at the prediction of the human foot behavior and the deformation under different load conditions. It also represents the starting point to develop a scientific approach for the functional mass customization aimed at the optimization of comfort in footwear. Reverse Engineering (RE) methodologies developed for building up the external shape of the human foot are presented and discussed. Aim of this work is to study the problem of the digitalization of human feet under different conditions using three technologies: shape from stereo, from silhouette and from shading. The foot is one of the most difficult human parts to reconstruct taking into account the complex surface and the high curvature. In this article the disadvantage and advantage of each technique are analyzed. In particular tests about reliability and precision of the measure are considered. © 2010 Society for Experimental Mechanics Inc.

The success of regenerative medicine is strongly dependent on the ability to produce biomimetic scaffolds that closely mimic the biomechanical properties of the native tissues. Additive biomanufacturing techniques have been recently introduced in the medical field and are increasingly being recognized as ideal methods to produce 3D porous structures with an effective control over pore size/shape and spatial distribution. The BioExtruder is an additive biomanufacturing system under development for Tissue Engineering (TE) applications. The working principle is based on the extrusion of thin filaments of low melting point materials in a layer-by-layer fashion, controlled by a computer model. There are several parameters that control the BioExtruder and that have a direct influence on the morphological and mechanical properties of the extruded scaffolds. In this study we have focused our investigations on four parameters, namely the Liquefier Temperature (LT), Screw Rotation Velocity (SRV), Deposition Velocity (DV) and Slice Thickness (ST). © 2010 Taylor & Francis Group, London.

Purpose: The importance of polymer-based composite materials to make multifunctional substrates for tissue engineering and the strategies to improve their performances have been stressed in the literature. Bioactive features of sol-gel synthesized poly(ε-caprolactone)/TiO2 or poly(ε-caprolactone)/ZrO2 organic-inorganic hybrid materials are widely documented. Accordingly, the aim of this preliminary research was to develop advanced composite substrates consisting of a poly(ε-caprolactone) matrix reinforced with sol-gel synthesized PCL/TiO2 or PCL/ZrO 2 hybrid fillers. Methods: Micro-computed tomography and atomic force microscopy analyses allowed to study surface topography and roughness. On the other hand, mechanical and biological performances were evaluated by small punch tests and Alamar Blueâ„¢ assay, respectively. Results: Micro-computed tomography and atomic force microscopy analyses highlighted the effect of the preparation technique. Results from small punch tests and Alamar Blueâ„¢ assay evidenced that PCL reinforced with Ti2 (PCL=12, TiO2=88 wt%) and Zr2 (PCL=12, ZrO2=88 wt%) hybrid fillers provided better mechanical and biological performances. Conclusions: PCL reinforced with Ti2 (PCL=12, TiO2=88 wt%) and Zr2 (PCL=12, ZrO2=88 wt%) hybrid fillers could be considered as advanced composite substrates for hard tissue engineering. © 2010 Società Italiana Biomateriali.

Keywords: Alamar Blue™ , Assay , Atomic force microscopy , Composite substrate , Organic-inorganic hybrid , Poly(ε-caprolactone) , Small punch test

Objective: The effect of a novel light curing process, namely soft light energy release (SLER®), on shrinkage, mechanical strength and residual stress of four dental restorative materials (DEI experience, Gradia Direct, Enamel Plus HFO and Venus) was investigated. Methods: Composite specimens were fast cured through high level of power density and soft light energy release. Temperature, linear shrinkage and light power measurements were acquired in parallel in order to assess the effect of light modulation on temperature and shrinkage profiles during the light curing process and the following dark reaction phase. The small punch test and Raman spectroscopy were adopted to investigate the effect of SLER® on mechanical strength and on internal stress, respectively. Results: The soft light energy release photo-polymerization allows to reduce of about 20% the shrinkage rate and to increase the strength of fast light cured specimens. In addition, a more relaxed and homogeneous internal stress distribution was observed. Significance: Properties of fast cured restorative materials can be improved by adopting the soft light energy release process. © 2010 Academy of Dental Materials.

Keywords: Composite , Contraction stress , Fast curing , Photo-polymerization , Shrinkage , Small punch test , Temperature

Scaffolds should possess suitable properties to play their specific role. In this work, the potential of 3D fiber deposition technique to develop multifunctional and well-defined magnetic poly(ε-caprolactone)/iron oxide scaffolds has been highlighted, and the effect of iron oxide nanoparticles on the biological and mechanical performances has been assessed. © 2010 American Institute of Physics.

Keywords: 3D fiber deposition , Iron oxide nanoparticles , Poly(ε-caprolactone) , Scaffolds , Tissue engineering

Tissue engineering may be defined as the application of biological, chemical and engineering principles toward the repair, restoration or regeneration of living tissue using biomaterials, cells and biologically active molecules alone or in combinations. The rapid restoration of tissue biomechanical function represents a great challenge, highlighting the need to mimic tissue structure and mechanical behavior through scaffold designs. For this reason, several biodegradable and bioresorbable materials, as well as technologies and scaffold designs, have been widely investigated from an experimental and/or clinical point of view. Accordingly, this review aims at stressing the importance of polymer-based composite materials to make multifunctional scaffolds for tissue engineering, with a special focus on bone, ligaments, meniscus and cartilage. Moreover, polymer-based nanocomposites will also be briefly introduced as an interesting strategy to improve the biological and mechanical performances of polymer scaffolds, especially for bone tissue engineering. © 2010 Società Italiana Biomateriali.

Keywords: Bone , Cartilage , Composites , Ligaments , Meniscus , Polymers , Scaffolds

The tissue engineering of tendon was studied using highly elastic poly(L-lactide-co-ε-caprolactone) (PLCL) scaffolds and focusing on the effect of dynamic tensile stimulation. Tenocytes from rabbit Achilles tendon were seeded (1.0 × 106 cells/scaffold) onto porous PLCL scaffolds and cultured for periods of 2 weeks and 4 weeks. This was performed in a static system and also in a bioreactor equipped with tensile modulation which mimicked the environmental surroundings of tendons with respect to tensile extension. The degradation of the polymeric scaffolds during the culture was relatively slow. However, there was an indication that cells accelerated the degradation of PLCL scaffolds. The scaffold/cell adducts from the static culture exhibited inferior strength (at 2 weeks 350 kPa, 4 weeks 300 kPa) compared to the control without cells (at 2 weeks 460 kPa, 4 weeks 340 kPa), indicating that the cells contributed to the enhanced degradation. On the contrary, the corresponding values of the adducts from the dynamic culture (at 2 weeks 430 kPa, 4 weeks 370 kPa) were similar to, or higher than, those from the control. This could be explained by the increased quantity of cells and neo-tissues in the case of dynamic culture compensating for the loss in tensile strength. Compared with static and dynamic culture conditions, mechanical stimulation played a crucial role in the regeneration of tendon tissue. In the case of the dynamic culture system, cell proliferation was enhanced and secretion of collagen type I was increased, as evidenced by DNA assay and histological and immunofluorescence analysis. Thus, tendon regeneration, indicated by improved mechanical and biological properties, was demonstrated, confirming the effect of mechanical stimulation. It could be concluded that the dynamic tensile stimulation appeared to be an essential factor in tendon/ligament tissue engineering, and that elastic PLCL co-polymers could be very beneficial in this process. © 2010 Koninklijke Brill NV, Leiden.

Keywords: BIOREACTOR , MECHANICAL STIMULATION , PLCL , TENDON , TISSUE ENGINEERING