Abstract: Cardiovascular diseases (CVD) are related to affectations of the heart and blood vessels, within these are pathologies such as coronary or peripheral heart disease, caused by the narrowing of the vessel wall (atherosclerosis), which is related to the accumulation of Low-Density Lipoproteins (LDL) in the arterial walls that leads to a progressive reduction of the lumen of the vessel and alterations in blood perfusion. Currently, the main therapeutic strategy for this type of alteration is drug treatment with statins, which inhibit the enzyme 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase), responsible for modulating the rate of cholesterol production and other isoprenoids in the mevalonate pathway. This enzyme induces the expression of LDL receptors in the liver, increasing their number on the surface of liver cells, reducing the plasma concentration of cholesterol. On the other hand, when the blood vessel presents stenosis, a surgical procedure with vascular implants is indicated, which are used to restore circulation in the arterial or venous bed. Among the materials used for the development of vascular implants are Dacron® and Teflon®, which perform the function of re-waterproofing the circulatory circuit, but due to their low biocompatibility, they do not have the ability to promote remodeling and tissue regeneration processes. Based on this, the present research proposes the development of a hydrolyzed collagen and polyethylene oxide electrospun membrane reinforced with medium and high-intensity statins, so that in future research it can favor tissue remodeling processes from its microarchitecture.
Abstract: Magnetically controlled growing rods (MCGRs) have been used to stabilise and correct spinal curvature in children to support non-invasive scoliosis adjustment. Although the encapsulated driving components are intended to be isolated from body fluid contact, in vivo corrosion was observed on these components due to sealing mechanism damage. Consequently, a corrosion circuit is created with the body fluids, resulting in malfunction of the lengthening mechanism. Particularly, the chloride ions in blood plasma or cerebrospinal fluid (CSF) may corrode the MCGR alloys, possibly resulting in metal ion release in long-term use. However, there is no data available on the corrosion resistance of spinal implant alloys in CSF. In this study, an in vitro immersion configuration was designed to simulate in vivo corrosion of 440C SS-Ti6Al4V couples. The 440C stainless steel (SS) was heat-treated to investigate the effect of tempering temperature on intergranular corrosion (IGC), while crevice and galvanic corrosion were studied by limiting the clearance of dissimilar couples. Tests were carried out in a neutral artificial cerebrospinal fluid (ACSF) and phosphate-buffered saline (PBS) under aeration and deaeration for 2 months. The composition of the passive films and metal ion release were analysed. The effect of galvanic coupling, pH, dissolved oxygen and anion species on corrosion rates and corrosion mechanisms are discussed based on quantitative and qualitative measurements. The results suggest that ACSF is more aggressive than PBS due to the combination of aggressive chlorides and sulphate anions, while phosphate in PBS acts as an inhibitor to delay corrosion. The presence of Vivianite on the SS surface in PBS lowered the corrosion rate (CR) more than 5 times for aeration and nearly 2 times for deaeration, compared with ACSF. The CR of 440C is dependent on passive film properties varied by tempering temperature and anion species. Although the CR of Ti6Al4V is insignificant, it tends to release more Ti ions in deaerated ACSF than under aeration, about 6 µg/L. It seems the crevice-like design has more effect on macroscopic corrosion than combining the dissimilar couple, whereas IGC is dominantly observed on sensitized microstructure.
Abstract: In the present work, reverse engineering approach has been used to create a 3D model of a fractured femur diaphysis bone using the computed tomography (CT) scan data. Thereafter, a counter fit fixation plate of polyetheretherketone (PEEK) composite has been designed and analyzed considering static physiological loading conditions. Static stress distribution and deformation analysis of the plate have been performed. From the analysis, it has been found that the stresses and deformation developed are quite low. This implies that these designed fixation plates will be able to provide stable fixation and thus resulting in improved fracture union.
Abstract: The mineral in human bone is not pure stoichiometric calcium phosphate (Ca/P) as it is partially substituted by in organic elements. In this study, the copper ions (Cu2+) substituted hydroxyapatite (CuHA) powder has been synthesized by the co-precipitation method. The CuHA powder has been used to fabricate CuHA fiber scaffolds by sol-gel process and the following sinter process. The resulted CuHA fibers have slightly different microstructure (i.e. porosity) compared to HA fiber scaffold, which is denser. The mechanical properties test was used to evaluate CuHA, and the results showed decreases in both compression strength and hardness tests. Moreover, the in vitro used endothelial cells to evaluate the angiogenesis of CuHA. The result illustrated that the viability of endothelial cell on CuHA fiber scaffold surfaces tends to antigenic behavior. The results obtained with CuHA scaffold give this material benefit in biological applications such as antimicrobial, antitumor, antigens, compacts, filling cavities of the tooth and for the deposition of metal implants anti-tumor, anti-cancer, bone filler, and scaffold.
Abstract: Bioactive glasses (BGs) are a group of surface-reactive biomaterials used in clinical applications as implants or filler materials in the human body to repair and replace diseased or damaged bone. Sol-gel technique was employed to prepare a SiO2-CaO-P2O5 glass with nominal composition of 58S BG with the addition of Sr and Li modifiers which imparts special properties to the BG. The effect of simultaneous addition of Sr and Li on bioactivity and biocompatibility, proliferation, alkaline phosphatase (ALP) activity of osteoblast cell line MC3T3-E1 and antibacterial property against methicillin-resistant Staphylococcus aureus (MRSA) bacteria were examined. BGs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy before and after soaking the samples in the simulated body fluid (SBF) for different time intervals to characterize the formation of hydroxyapatite (HA) formed on the surface of BGs. Structural characterization indicated that the simultaneous presence of 5% Sr and 5% Li in 58S-BG composition not only did not retard HA formation because of opposite effect of Sr and Li of the dissolution of BG in the SBF but also, stimulated the differentiation and proliferation of MC3T3-E1s. Moreover, the presence of Sr and Li on dissolution of the ions resulted in an increase in the mean number of DAPI-labeled nuclei which was in good agreement with live/dead assay. The result of antibacterial tests revealed that Sr and Li-substituted 58S BG exhibited a potential antibacterial effect against MRSA bacteria. Because of optimal proliferation and ALP activity of MC3T3-E1cells, proper bioactivity and high antibacterial potential against MRSA, BG-5/5 is suggested as a multifunctional candidate for bone tissue engineering.
Abstract: The host response in peri-implant tissue may differ from that in periodontal tissue in a healthy individual. The purpose of this study is to investigate the expression of inflammatory cytokines in peri-implant crevicular fluid (PICF) from single implant with different abutment types in comparison to healthy periodontal tissue. 19 participants with healthy implants and teeth were recruited according to inclusion and exclusion criteria. PICF and gingival crevicular fluid (GCF) was collected using sterile paper points. The expression level of inflammatory cytokines including IL-1α, IL-1β, TNF-α, IFN-γ, IL-6, and IL-8 was assessed using enzyme-linked immunosorbent assay (ELISA). Paired t test was used to compare the expression levels of inflammatory cytokines around natural teeth and peri-implant in PICF and GCF of the same individual. The Independent t-test was used to compare the expression levels of inflammatory cytokines in PICF from titanium and UCLA abutment. Expression of IL-6, TNF-α, and IFN-γ in PICF was not statistically different from GCF among titanium and UCLA abutment group. However, the level of IL-1α in the PICF from the implants with UCLA abutment was significantly higher than GCF (P=0.030). In addition, the level of IL-1β in PICF from the implants with titanium abutment was significantly higher than GCF (P=0.032). When different abutment types was compared, IL-8 expression in PICF from implants with UCLA abutment was significantly higher than titanium abutment (P=0.003).
Abstract: Many orthopedic implants like proximal humerus cases require lower surface roughness and almost immediate/short lead time surgery. Thus, rapid response from the manufacturer is very crucial. Tool path strategy of milling process has a direct influence on the surface roughness and lead time of medical implant. High-speed milling as promised process would improve the machined surface quality, but conventional or super-abrasive grinding still required which imposes some drawbacks such as additional costs and time. Currently, many CAD/CAM software offers some different tool path strategies to milling free form surfaces. Nevertheless, the users must identify how to choose the strategies according to cutting tool geometry, geometry complexity, and their effects on the machined surface. This study investigates the effect of different tool path strategies for milling a proximal humerus head during finishing operation on stainless steel 316L. Experiments have been performed using MAHO MH700 S vertical milling machine and four machining strategies, namely, spiral outward, spiral inward, and radial as well as zig-zag. In all cases, the obtained surfaces were analyzed in terms of roughness and dimension accuracy compared with those obtained by simulation. The findings provide evidence that surface roughness, dimensional accuracy, and machining time have been affected by the considered tool path strategy.
Abstract: COMTES FHT has been active in a field of research and development of high-strength wires for quite some time. The main material was pure titanium. The primary goal of this effort is to develop a continuous production process for ultrafine and nanostructured materials with the aid of severe plastic deformation (SPD). This article outlines mechanical and microstructural properties of the materials and the options available for testing the components made of these materials. Ti Grade 2 and Grade 4 wires are the key products of interest. Ti Grade 2 with ultrafine to nano-sized grain shows ultimate strength of up to 1050 MPa. Ti Grade 4 reaches ultimate strengths of up to 1250 MPa. These values are twice or three times as higher as those found in the unprocessed material. For those fields of medicine where implantable metallic materials are used, bulk ultrafine to nanostructured titanium is available. It is manufactured by SPD techniques. These processes leave the chemical properties of the initial material unchanged but markedly improve its final mechanical properties, in particular, the strength. Ultrafine to nanostructured titanium retains all the significant and, from the biological viewpoint, desirable properties that are important for its use in medicine, i.e. those properties which made pure titanium the preferred material also for dental implants.
Abstract: Previously, some materials like solid metals and their alloys have been used as implants in human’s body. In order to amend fixation of these artificial hard human tissues, some porous structures have been introduced. In this way, tissues in vicinity of the porous structure can be attached more easily to the inserted implant. In particular, the porous bone scaffolds are useful since they can deliver important biomolecules like growth factors and proteins. This study focuses on the properties of the degradable porous hard tissues using a three-dimensional numerical Finite Element Method (FEM). The most important studied properties of these structures are diffusivity flux and concentration of different species like glucose, oxygen, and lactate. The process of cells migration into the scaffold is considered as a diffusion process, and related parameters are studied for different values of production/consumption rates.
Abstract: Titanium and its alloys have been used extensively over the past 25 years as biomedical materials in orthopedic and dental applications because of their good mechanical properties, corrosion resistance, and biocompatibility. It is known that the surface properties of titanium implants can enhance the cellular response and play an important role in Osseo integration. The rate and quality of Osseo integration in titanium implants are related to their surface properties. The purpose of this investigation was to evaluate the effect of sandblasting and acid etching on surface morphology, roughness, the wettability of titanium. The surface properties will be characterized by scanning electron microscopy and contact angle and roughness measurements. The results show that surface morphology, roughness, and wettability were changed and enhanced by these treatments.
Abstract: Present project consists in a study and a development
of piezoelectric devices for supplying power to new generation
pacemakers. They are miniaturized leadless implants without battery
placed directly in right ventricle. Amongst different acceptable
energy sources in cardiac environment, we choose the solution of a
device based on conversion of the energy produced by pressure
variation inside the heart into electrical energy. The proposed energy
harvesters can meet the power requirements of pacemakers, and can
be a good solution to solve the problem of regular surgical operation.
With further development, proposed device should provide enough
energy to allow pacemakers autonomy, and could be good candidate
for next pacemaker generation.
Abstract: Excessive fretting wear at the taper-trunnion junction
(trunnionosis) apparently contributes to the high failure rates of hip
implants. Implant wear and corrosion lead to the release of metal
particulate debris and subsequent release of metal ions at the tapertrunnion
surface. This results in a type of metal poisoning referred to
as metallosis. The consequences of metal poisoning include;
osteolysis (bone loss), osteoarthritis (pain), aseptic loosening of the
prosthesis and revision surgery. Follow up after revision surgery,
metal debris particles are commonly found in numerous locations. Background: A stable connection between the femoral ball head
(taper) and stem (trunnion) is necessary to prevent relative motions
and corrosion at the taper junction. Hence, the importance of
component assembly cannot be over-emphasized. Therefore, the aim
of this study is to determine the influence of head-stem junction
assembly by press fitting and the subsequent
disengagement/disassembly on the connection strength between the
taper ball head and stem. Methods: CoCr femoral heads were assembled with High stainless
hydrogen steel stem (trunnion) by Push-in i.e. press fit; and
disengaged by pull-out test. The strength and stability of the two
connections were evaluated by measuring the head pull-out forces
according to ISO 7206-10 standards. Findings: The head-stem junction strength linearly increases with
assembly forces.
Abstract: In IA-MDT, the magnetic implants are placed
strategically at the target site to greatly and locally increase the
magnetic force on MDCPs and help to attract and retain the MDCPs
at the targeted region. In the present work, we develop a
mathematical model to study the capturing of magnetic nanoparticles
flowing within a fluid in an implant assisted cylindrical channel
under magnetic field. A coil of ferromagnetic SS-430 has been
implanted inside the cylindrical channel to enhance the capturing of
magnetic nanoparticles under magnetic field. The dominant magnetic
and drag forces, which significantly affect the capturing of
nanoparticles, are incorporated in the model. It is observed through
model results that capture efficiency increases as we increase the
magnetic field from 0.1 to 0.5 T, respectively. The increase in capture
efficiency by increase in magnetic field is because as the magnetic
field increases, the magnetization force, which is attractive in nature
and responsible to attract or capture the magnetic particles, increases
and results the capturing of large number of magnetic particles due to
high strength of attractive magnetic force.
Abstract: Ti6Al4V alloy is highly used in the automotive and
aerospace industry due to its good machining characteristics. Micro
EDM drilling is commonly used to drill micro hole on extremely hard
material with very high depth to diameter ratio. In this study, the
parameters of micro-electrical discharge machining (EDM) in drilling
of Ti6Al4V alloy is optimized for higher machining accuracy with
less hole-dilation and hole taper ratio. The micro-EDM machining
parameters includes, peak current and pulse on time. Fuzzy analysis
was developed to evaluate the machining accuracy. The analysis
shows that hole-dilation and hole-taper ratio are increased with the
increasing of peak current and pulse on time. However, the surface
quality deteriorates as the peak current and pulse on time increase.
The combination that gives the optimum result for hole dilation is
medium peak current and short pulse on time. Meanwhile, the
optimum result for hole taper ratio is low peak current and short pulse
on time.
Abstract: Bone properties and response behavior after static or
dynamic activation (loading) are still interesting topics in many fields
of the science especially in the biomechanical problems such as bone
loss of astronauts in space, osteoporosis, bone remodeling after
fracture or remodeling after surgery (endoprosthesis and implants)
and in osteointegration. This contribution deals with the relation
between physiological, demineralized and deproteinized state of the
turkey long bone – tibia. Three methods for comparison were used: 1)
densitometry, 2) three point bending and 3) frequency analysis. The
main goal of this work was to describe the decrease of the protein
(collagen) or mineral of the bone with relation to the fracture in three
point bending. The comparison is linked to the problem of different
bone mechanical behavior in physiological and osteoporotic state.
Abstract: In this research work, neural networks were applied to
classify two types of hip joint implants based on the relative hip joint
implant side speed and three components of each ground reaction
force. The condition of walking gait at normal velocity was used and
carried out with each of the two hip joint implants assessed. Ground
reaction forces’ kinetic temporal changes were considered in the first
approach followed but discarded in the second one. Ground reaction
force components were obtained from eighteen patients under such
gait condition, half of which had a hip implant type I-II, whilst the
other half had the hip implant, defined as type III by Orthoload®.
After pre-processing raw gait kinetic data and selecting the time
frames needed for the analysis, the ground reaction force components
were used to train a MLP neural network, which learnt to distinguish
the two hip joint implants in the abovementioned condition. Further
to training, unknown hip implant side and ground reaction force
components were presented to the neural networks, which assigned
those features into the right class with a reasonably high accuracy for
the hip implant type I-II and the type III. The results suggest that
neural networks could be successfully applied in the performance
assessment of hip joint implants.
Abstract: Biometallic materials are the most important materials for use in biomedical applications especially in manufacturing a variety of biological artificial replacements in a modern worlds, e.g. hip, knee or shoulder joints, due to their advanced characteristics. Titanium (Ti) and its alloys are used extensively in biomedical applications based on their high specific strength and excellent corrosion resistance. Beta-Ti alloys containing completely biocompatible elements are exceptionally prospective materials for manufacturing of bioimplants. They have superior mechanical, chemical and electrochemical properties for use as biomaterials. These biomaterials have the ability to introduce the most important property of biochemical compatibility which is low elastic modulus. This review examines current information on the recent developments in alloying elements leading to improvements of beta Ti alloys for use as biomaterials. Moreover, this paper focuses mainly on the evolution, evaluation and development of the modulus of elasticity as an effective factor on the performance of beta alloys.
Abstract: Electron Beam Melting (EBM) process was used to prepare porous scaffolds with controlled porosity to ensure optimal levels of osteointegration for different trabeculae sizes. Morphological characterization by means of SEM analyses was carried out to assess pore dimensions; tensile, compression and adhesion tests have been carried out to determine the mechanical behavior. The results indicate that EBM process allows the creation of regular and repeatable porous scaffolds. Mechanical properties greatly depend on pore dimension and on bulk-pore ratio. Adhesion resistance meets the normative requirements, and the overall performance of the produced structures is compatible with potential orthopaedic applications.
Abstract: Bone Anchored Hearing Implants (BAHI) are
routinely used in patients with conductive or mixed hearing loss, e.g.
if conventional air conduction hearing aids cannot be used. New
sound processors and new fitting software now allow the adjustment
of parameters such as loudness compression ratios or maximum
power output separately. Today it is unclear, how the choice of these
parameters influences aided speech understanding in BAHI users.
In this prospective experimental study, the effect of varying the
compression ratio and lowering the maximum power output in a
BAHI were investigated.
Twelve experienced adult subjects with a mixed hearing loss
participated in this study. Four different compression ratios (1.0; 1.3;
1.6; 2.0) were tested along with two different maximum power output
settings, resulting in a total of eight different programs. Each
participant tested each program during two weeks. A blinded Latin
square design was used to minimize bias.
For each of the eight programs, speech understanding in quiet and
in noise was assessed. For speech in quiet, the Freiburg number test
and the Freiburg monosyllabic word test at 50, 65, and 80 dB SPL
were used. For speech in noise, the Oldenburg sentence test was
administered.
Speech understanding in quiet and in noise was improved
significantly in the aided condition in any program, when compared
to the unaided condition. However, no significant differences were
found between any of the eight programs. In contrast, on a subjective
level there was a significant preference for medium compression
ratios of 1.3 to 1.6 and higher maximum power output.
Abstract: In biomedical implant field, a new formula is given
for the study of Radio Frequency power attenuation by simultaneous
effects of side and angular misalignment of the supply/data transfer
coils. A confrontation with the practical measurements done into a
Faraday cage, allowed a checking of the obtained theoretical results.
The DC supply systems without material connection and the data
transmitters used in the case of biomedical implants, can be well
dimensioned by taking into account the possibility of power
attenuation by misalignment of transfer coils