C.S. Lambert

Cranial reconstruction: 3D biomodel and custom-built implant created using additive manufacturing.

Additive manufacturing (AM) technology from engineering has helped to achieve several advances in the medical field, particularly as far as fabrication of implants is concerned. The use of AM has made it possible to carry out surgical planning and simulation using a three-dimensional physical model which accurately represents the patients anatomy. AM technology enables the production of models and implants directly from a 3D virtual model, facilitating surgical procedures and reducing risks. Furthermore, AM has been used to produce implants designed for individual patients in areas of medicine such as craniomaxillofacial surgery, with optimal size, shape and mechanical properties. This work presents AM technologies which were applied to design and fabricate a biomodel and customized implant for the surgical reconstruction of a large cranial defect. A series of computed tomography data was obtained and software was used to extract the cranial geometry. The protocol presented was used to create an anatomic biomodel of the bone defect for surgical planning and, finally, the design and manufacture of the patient-specific implant.

Diamond-Like Carbon Coatings on Ti-13Nb-13Zr Alloy Produced by Plasma Immersion for Orthopaedic Applications

Diamond-like carbon (DLC) films have been intensively studied with a view to improving orthopaedic implants. Various techniques have been employed to manufa cture DLC films, and recently, the plasma immersion process has been used to pr ovide non-line-of-sight deposition on three-dimensional pieces with complex shapes. In this method, the whole surface of the target is coated, even without moving the sample, and without an inte rmediate layer. DLC films were deposited on a silicon wafer and Ti-13Nb-13Zr alloy substrates, us ing the plasma immersion process. The films were analysed by Raman spectroscopy, atomic for ce microscopy (AFM), and nanoindentation. As examples, uniformly DLC coated orthopaedic implants (kne e implant and femoral head) are shown. Introduction Diamond-like carbon (DLC) films are often considered a suitable coa ting material for orthopaedic applications. It has proven characteristics, such as hardness, wear r esistance, low friction coefficient and biocompatibility that improve the properties of solid and articulated implants [1,2]. DLC coatings can be deposited using various techniques, such as plasma e nhanced chemical vapour deposition, magnetron sputtering, laser ablation, and others [3]. Recent ly, the plasma immersion process was used to deposit DLC films with superior adhes ion properties [4,5]. In the plasma immersion process, a developing technique for surface modificat ion of three-dimensional components, pulsed high negative voltage is applied to the target, producing a plasma, and the total surface of the target is coated, even without moving the sample, and without an intermedia t layer. Titanium alloys are widely used as biomaterials, because they ha v good corrosion resistance and desirable mechanical properties close to those of bone [6]. However, ti tanium alloys have relatively poor resistance against wear and a high friction coefficient. A D LC film could be used to protect titanium-based implants, improving wear behaviour and surface hardness. Ti-6Al-4V alloy has been extensively used for many years as an i mplantable material mainly in the application of orthopaedic prostheses. However, the toxicity of Vanadi um and neurological disorders associated with Aluminium, have also created problems for bi ol gical applications, and new types of alloys have been developed [6,7]. Ti-13Nb-13Zr alloy has been propos ed as an alternative to the Ti-6Al-4V because of its superior corrosion resistance and biocom patibility. In this study, DLC coatings were deposited on Ti-13Nb-13Zr alloy substra te using the plasma immersion process. We characterized the films obtained using nanoindent ation, Raman spectroscopy, and atomic force microscopy (AFM). The study is in an i nitial phase and other analyses, as characterization of mechanical and tribological properties are unde way. Key Engineering Materials Online: 2003-12-15 ISSN: 1662-9795, Vols. 254-256, pp 435-438 doi:10.4028/www.scientific.net/KEM.254-256.435

Paired evaluation of calvarial reconstruction with prototyped titanium implants with and without ceramic coating

PURPOSE To investigate the osseointegration properties of prototyped implants with tridimensionally interconnected pores made of the Ti6Al4V alloy and the influence of a thin calcium phosphate coating. METHODS Bilateral critical size calvarial defects were created in thirty Wistar rats and filled with coated and uncoated implants in a randomized fashion. The animals were kept for 15, 45 and 90 days. Implant mechanical integration was evaluated with a push-out test. Bone-implant interface was analyzed using scanning electron microscopy. RESULTS The maximum force to produce initial displacement of the implants increased during the study period, reaching values around 100N for both types of implants. Intimate contact between bone and implant was present, with progressive bone growth into the pores. No significant differences were seen between coated and uncoated implants. CONCLUSION Adequate osseointegration can be achieved in calvarial reconstructions using prototyped Ti6Al4V Implants with the described characteristics of surface and porosity.

Titanium Oxide (TiO2) Coatings Produced on Titanium by Oxygen-Plasma Immersion and Cell Behaviour on TiO2

Plasma immersion process was investigated as a method for producing bioceramics coatings on metallic implants due to its advantages, which include the production of coatings on three-dimensional workpieces, with high density and superior adhesion. In this process, the oxygen plasma was utilized to form titanium oxide on titanium substrate. The structure, composition and surface morphology were studied using scanning electron microscopy (SEM) and X-ray diffraction. In addition a preliminary study has also been carried out, on TiO2-coated and uncoated titanium substrates, to analyse the in vitro biocompatibility (cytotoxicity evaluation and cell morphology).

Biocompatibility of Titanium Based Implants with Diamond-Like Carbon Coatings Produced by Plasma Immersion Ion Implantation and Deposition

A great number of studies have shown that diamond-like carbon (DLC) coatings could be developed for orthopaedic implants, but few articles have been published about in vivo evaluation. In this study, DLC coatings were deposited on titanium alloy (Ti-13Nb-13Zr) implants using the plasma immersion implantation and deposition (PIII-D), and the in vivo biocompatibility of DLC coatings was evaluated into both muscular tissue and femoral condyles of rats. Results indicate that DLC coatings are biocompatible in vivo, and DLC-coated implants were observed directly bonding to bone without any intervening soft tissue layer.

Atomic Force Microscopic Observations of Diamond-like Carbon (DLC) Films Produced by Plasma Immersion and Fibroblasts Cultured on DLC

Diamond-like carbon (DLC) films have been intensively studied with a view to improving orthopaedic implants. Studies have indicated smoothness of the surface, low friction, high wear resistance, corrosion resistance and biocompatibility [1-4]. DLC coatings can be deposited using various techniques, such as plasma assisted chemical vapour deposition (PACVD), magnetron sputtering, laser ablation, and others [5]. However it has proved difficult to obtain films which exhibit good adhesion. The plasma immersion process, unlike the conventional techniques, allows the deposition of DLC on three-dimensional workpieces, even without moving the sample, without an intermediate layer, and with high adhesion [6], an important aspect for orthopaedic articulations. In our previous work, DLC coatings were deposited on silicon and Ti-13Nb-13Zr alloy substrates using the plasma immersion process for the characterization of microstructure, mechanical properties and corrosion behaviour [7-9]. Hardness, measured by a nanoindenter, ranged from 16.417.6 GPa, the pull test results indicate the good adhesion of DLC coatings to Ti-13Nb-13Zr, and electrochemical assays (polarization test and electrochemical impedance spectroscopy) indicate that DLC coatings produced by plasma immersion can improve the corrosion resistance [9]. Before any material is used for medical purposes, it must pass a series of tests in terms of its biocompatibility and toxicity to the tissue. Evaluation of biocompatibility using in vitro techniques is well established as a valid initial step in the testing of biomaterials, and permits a fast evaluation of the biological performance of the material to be studied [10,11]. It is important to evaluate the cell-biomaterial interaction for the prediction of possible reactions to the DLC in vivo when used as coating of the biomaterials. Thomson et al [1] have studied the DLC-coated tissue culture plates in their pioneering work on the biocompatibility of DLC coatings, Allen et al [2] studied the effects of DLC-coated polystyrene plates, Butter et al [3] studied DLC-coated glass coverslips with an intermediate layer of silicon to improve the adhesion of the DLC layer, and Linder et al [4] analysed the biocompatibility of DLC-coated glass coverslips formed by PACVD. The results indicated the biocompatibility of the DLC coatings. The plastic plates and glass coverslips (produced for cellular culture) are considered a good substrate because are available commercially, are in agreement with the ISO 10993-5 [10], are transparent (necessary for cytochemical studies, analysis by light microscope, and immunofluorescence technique which distinct cytoskeletal elements), possess known cellular response, and, therefore, can be used in the comparison of results of the literature. It is important to standardize the results, because the cells are sensitive to the physical and chemical

Morphology of Fibroblastic Cells Cultured on Diamond-Like Carbon Coatings Produced by Plasma Immersion Using AFM and SEM

For the potential use of diamond-like carbon (DLC) coating for biomedical applications, it would be important to evaluate the biological effects of these coatings. In this study, DLC coatings were deposited on glass coverslips using the plasma immersion process, which produces films with adhesion properties superior to those prepared with conventional techniques. Scanning electron microscopic and atomic force microscopic observations were used to study the morphology of fibroblasts growth on DLC coatings.

Tissue Response in the Femur of Rats After Implantation of Diamond-Like Carbon Coatings on Ti-13Nb-13Zr Produced by Plasma Immersion

Diamond-like carbon (DLC) coatings were deposited on titanium alloy (Ti-13Nb-13Zr) by plasma immersion process. DLC-coated Ti alloy and uncoated Ti were investigated in an animal model using the femoral condyles of rats for intervals of 4 and 12 weeks postoperatively. The interface between the implants and bones of the femoral condyles were analysed using scanning electron microscopy (SEM) by backscattering. The results showed that the DLC coatings were well tolerated in both periods.

Characterization of Titanium Oxide Thin Films Produced by Plasma Immersion Ion Implantation for Biomedical Implants

Plasma immersion ion implantation (PIII) is a very attractive method for the surface treatment of titanium hard tissue replacements such as hip joints and enhancement of the mechanical, chemical and biological properties of titanium. It has been considered as an alternative to form protective and hard oxide films on titanium and titanium-based implants. In this study, titanium oxide (TiO2) thin films were formed on titanium using PIII, which produces films with adhesion superior to those prepared with conventional techniques. The films were analysed by atomic force microscopy (AFM), X-ray diffraction (XRD) and pull test.

Porous Bioceramics (Open Cell Foams) Expanded in Vacuum

In this study, porous bioceramics (titanium foam with diamond-like carbon coatings, glass foam and zirconium oxide foam) were produced using expansion in vacuum. The porosity, the pore size and pore morphology can be adjusted in agreement with the application. The different 3D structures were obtained by varying the parameters of the process. The microstructure and morphology of the porous materials were observed by scanning electron microscopy (SEM) and optical microscopy. The foam exhibit an open-cell structure with interconnected macropores, which provide the potential for tissue ingrowths and the transport of the body fluids.