Bio-Medical Materials and Engineering - Volume 13, issue 4
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Bio-Medical Materials and Engineering is to promote the welfare of humans and to help them keep healthy. This international journal is an interdisciplinary journal that publishes original research papers, review articles and brief notes on materials and engineering for biological and medical systems.
Articles in this peer-reviewed journal cover a wide range of topics, including, but not limited to: Engineering as applied to improving diagnosis, therapy, and prevention of disease and injury, and better substitutes for damaged or disabled human organs; Studies of biomaterial interactions with the human body, bio-compatibility, interfacial and interaction problems; Biomechanical behavior under biological and/or medical conditions; Mechanical and biological properties of membrane biomaterials; Cellular and tissue engineering, physiological, biophysical, biochemical bioengineering aspects; Implant failure fields and degradation of implants. Biomimetics engineering and materials including system analysis as supporter for aged people and as rehabilitation; Bioengineering and materials technology as applied to the decontamination against environmental problems; Biosensors, bioreactors, bioprocess instrumentation and control system; Application to food engineering; Standardization problems on biomaterials and related products; Assessment of reliability and safety of biomedical materials and man-machine systems; and Product liability of biomaterials and related products.
Abstract: Fibroin‐hydrogel sponge and collagen gel were used as scaffold for in vitro cartilage regeneration. Fibroin‐hydrogel sponge was formed by phase separation from freezed fibroin solution. Chondrocytes were harvested from proximal humerus, distal femur and proximal tibia of 4‐week‐old Japanese white rabbits and inoculated in the fibroin–hydrogel sponge and collagen gel. Those constructs were cultured in DMEM supplemented with 10% FCS and 50 ml L‐ascorbate at 37°C. Histological observation, measurement of sulfated glycosaminoglycan and cell density were carried out at 3, 7, and 14 days after the cultivation. Well‐defined cartilage tissue can be seen both in the fibroin–hydrogel sponge and…in the collagen gel. The matrix was intensely stained by safranin‐O and showed a metachromatic reaction in both group. However, the quantity of sulfated glycosaminoglycan and cell density of the fibroin–hydrogel sponge group were increased more rapidly than these of the collagen gel group. Thus, the chondrocytes proliferated in the fibroin sponge without losing their differentiated phenotype. It is possible that culture environment in the fibroin sponge was suitable for chondrocytes regeneration.
Abstract: In revision surgeries of endoprostheses, the interface between implant and bone cement or bone must be loosened. Conventional tools have many disadvantages because of their size and limited range. Taking advantage of the selective and athermic cutting process, a plain water jet is already used in order to cut soft tissues. This study investigates the possibilities of both a plain and an abrasive water jet as cutting tools for revision surgery. Samples of the mid‐diaphysis of human femora and bone cement (CMW3) were cut with a plain water jet (PWJ) and an abrasive water jet (AWJ) at two different…jet‐to‐surface angles (30°,90°) and at five different pressure levels (30, 40, 50, 60, 70 MPa). For a PWJ a selective pressure range was identified, where only bone cement was cut. Injecting a bio‐compatible abrasive (lactose) to the jet stream resulted in significantly higher cut depths in both materials. Material removal in bone was significantly less at the smaller jet‐to‐surface angle for both techniques. No clear selectivity between bone and bone cement was observed for application of the AWJ. However, the material removal rate was significantly higher for bone cement than for bone at all pressure levels. The results indicate that an AWJ might be an alternative tool for cement removal. The possibility for localised cutting at interfaces could be an advantage for revision of a non‐cemented prosthesis.
Keywords: Jet cutting, prosthesis, revision, bone cement, bone
Abstract: The placement of angiographic catheters into the vascular system is a routine procedure in modern clinical business. The definition of objective but not yet available evaluation protocols based on measurable physical quantities correlated to the empirical clinical findings is of utmost importance for catheter manufacturers for in‐house product screening and optimization. In this context, we present an assessment of multiple mechanical and surface catheter properties such as static and kinetic friction, bending stiffness, microscopic surface topology, surface roughness, surface free energy and their interrelation. Theoretical framework, description of experimental methods and extensive data measured on several different catheters are provided…and in conclusion a testing procedure is defined. Although this procedure is based on the measurement of several physical quantities it can be easily implemented by commercial laboratories testing catheters as it is based on relatively low‐cost standard methods.
Abstract: The dynamic visco‐elastic properties of regenerated cartilage tissue were measured to evaluate its mechanical function during cultivation. Harvested chondrocytes from 4‐week‐old Japanese white rabbits were inoculated into fibroin sponge at a cell concentration of about 5×107 cells/ml. Dynamic visco‐elasticity measurements were performed under compressive loading to evaluate the load bearing function of the articular cartilage. The dynamic modulus and the dynamic loss of the regenerated cartilage increased and the peak value of tanδ, as well as the frequency at the peak, decreased with increasing cultivation time. The pores of the fibroin sponge became filled with newly formed tissue as…cultivation time increased. These changes in the visco‐elastic properties of the regenerated cartilage were compared with those of a model system, ethylene propylene diene monomer sponge with interstitial fluid, and appear to be a result of increased fluid flow resistance and internal loss. We conclude that the changes in the dynamic visco‐elastic properties of the regenerated cartilage were caused because of narrowing of the fluid path by synthesized extracellular matrix.
Abstract: To evaluate the deterioration in the superelasticity of Ti‐coated NiTi orthodontic wires, titanium was coated onto wires to form a 1‐μm thick film using radio frequency magnetron sputtering. In superelasticity cycle tests, the σ5.0 value (the stress at 5.0% strain) of a Ti‐coated wire was lower than that of a non‐coated wire by 6.2% after one cycle, and by 10.4% after 20 cycles. In a three point bend tests, the L2.0 value (the load at 2.0 mm deflection) of a Ti‐coated wire was 2.55 N, and this was reduced by 39.0% of the L2.0 value of a…non‐coated wire (4.18 N). After the non‐coated and the Ti‐coated wires had been immersed in physiological saline for periods of four and eight weeks, the concentration of Ni ions released into each solution was detected using MIP‐Mass, and Ni peak intensity of the wires was measured using XPS. After eight weeks, the concentration of Ni ions released from the non‐coated and the Ti‐coated wires was 657 and 135 ppb, respectively. In a clinical test, no inflammation was observed during the entire attached period of four weeks in both the non‐coated and the Ti‐coated wire. In the Ti‐coated wire, little exfoliation of the Ti‐coating was observed using SEM and EDS. It was concluded that Ti‐coated NiTi orthodontic wire has much potential for its application, with a low probability of causing any Ni allergy.
Keywords: NiTi orthodontic wire, superelasticity, sputtering, titanium, Ni allergy
Abstract: Introducing the theory of fuzzy set, mathematical morphology and computerized mask fast scanning, we developed the TOOTH.SCA software and method to analyze the effect of fluoride (NaF) on ore content of human tooth enamel automatically and quantitatively. And we obtained some characteristic parameters, such as the depth, the type and the demineralized content of every scathing layer of dental caries. The smallest scale of mask scanning is 0.1 μm × 0.1 μm and the time required to analyze a sample is only 12 s. The applied software and method we built play an important role to the research on the…mechanism of pathological changes of teeth and preventing dental caries.
Keywords: Human tooth enamel, mineral matter, fluoride, image information processing, mask scanning
Abstract: In physiological loading conditions, the soft tissues in the hands and fingers are predominantly in compression. The goal of the present study was to characterize the nonlinear and time‐dependent behavior of skin in compression. The pigskin samples used in the study were collected from five different animals. The compression tests were performed in confined and unconfined loading configurations and at four different loading speeds (0.5, 1.0, 40, and 400 μm/s). A multi‐axial material model was proposed to simulate the nonlinear and viscoelastic behavior of the skin in compression. The good agreement between the model predictions and experimental data suggests that…the mechanical behavior of the skin in compression can be well characterized using the Ogden strain energy potential combined with a time‐integration using a Prony series. Our results show that the stress/strain curve of the skin is much stiffer in confined compression compared to that in unconfined compression, indicating that the compressibility of the skin is small.
Abstract: Superparamagnetic as well as fine ferrimagnetic particles such as Fe3 O4 , have been extensively used in magnetic field induced localized hyperthermia for the treatment of cancer. The magnetic materials with Curie temperature (Tc ) between 42 and 50°C, with sufficient biocompatibility are the best candidates for effective treatment such that during therapy it acts as in vivo temperature control switch and thus over heating could be avoided. Ultrafine particles of substituted ferrite Co1−a Zna Fe2 O4 and substituted yttrium–iron garnet Y3 Fe5−x Alx O12 have been prepared through microwave refluxing and citrate‐gel route respectively. Single‐phase compounds were…obtained with particle size below 100 nm. In order to make these magnetic nano particles biocompatible, we have attempted to coat these above said composition by alumina. The coating of alumina was done by hydrolysis method. The coating of hydrous aluminium oxide has been done over the magnetic particles by aging the preformed solid particles in the solution of aluminium sulfate and formamide at elevated temperatures. In vitro study is carried out to verify the innocuousness of coated materials towards cells. In vitro biocompatibility study has been carried out by cell culture method for a period of three days using human WBC cell lines. Study of cell counts and SEM images indicates the cells viability/growth. The in vitro experiments show that the coated materials are biocompatible.
Keywords: Magnetic hyperthermia, nanomagnetic materials, YIG, Co–Zn ferrites
Abstract: An injectable polydimethylsiloxane/hydroxyapatite (PDMS/HAp) composite cement was synthesised using linear PDMS and HAp (particles of about 100 nm in size) of different mass fractions. The effect of HAp mass fraction (5–60 mass%) on the hardness of PDMS/HAp composite cement was investigated. The hardness achieved is 25–49°ShA. Differential scanning calorimetry (DSC) was used to study the cross‐linking process and the influence of HAp on the temperature and duration of PDMS/HAp cross‐linking. The microstructure of composite cement surfaces after 10 days in vivo tests was observed by scanning electron microscopy (SEM). The presence of well‐adhered macrophages, fibroblasts and monocytes was found on…the implant surface upon its extraction from the organism.
Keywords: Composite cement, polydimethylsiloxane/hydroxyapatite, hardness, cross‐linking, in vivo test
Abstract: A new therapeutic system called the “total joint regeneration system” is proposed as a treatment for osteoarthritis and rheumatoid arthritis. We have developed devices which allow the regeneration of damaged cartilage under noninvasive mechanical stimulation. This paper introduces the basic concepts of total joint regeneration and reports the results of the first animal experiment using an internal‐fixator device using rabbits and a dog.
Keywords: Total joint regeneration, internal‐fixator device, cartilage
Abstract: The exothermic polymerization of bone cement may induce thermal necrosis of bone in cemented hip arthroplasty. A finite element formulation was developed to predict the evolution of the temperature with time in the cemented hip replacement system. The developed method is capable of taking into account both the chemical reaction that generates heat during bone cement polymerization (through a kinetic model) and the physical process of heat conduction (with an energy balance equation). The possibility of thermal necrosis of bone was then evaluated based on the temperature history in the bone and an appropriate damage criterion. Specifically, we evaluate the…role of implant materials and designs on the thermal response of the system. Results indicated that the peak temperature at the bone/cement interface with a metal prosthesis was lower than that with a polymer or a composite prosthesis in hip replacement systems. Necrosis of bone was predicted to occur with a polymer or a composite prosthesis while no necrosis was predicted with a metal prosthesis in the simulated conditions. When reinforcing osteoporotic hips with injected bone cement in the cancellous core of the femur, the volume of bone cement implanted is increased which may increase the risk of thermal necrosis of bone. We evaluate whether this risk can be decreased through the use of an insulator to contain the bone cement. No thermal necrosis of bone was predicted with a 3 mm thick polyurethane insulator while more damage is predicted for the use of bone cement without the insulator. This method provides a numerical tool for the quantitative simulation of the thermal behavior of bone‐cement‐prosthesis designs and for examining and refining new designs computationally.
Keywords: Bone cement, finite element, thermal behavior, prosthesis, orthopaedic
Abstract: The purpose of this study was to observe and compare the effect of the behavior of different lubricating surfaces, including articular cartilage and several artificial joint materials, under the physiological loading by confocal laser scanning microscopy (CLSM) to clarify the mechanism of lubrication in natural joints and subsequently improve the quality of artificial joints. In our experiment, even with considerable loading, natural articular cartilage exhibited a synovial fluid area and an area of direct and solid contact. In the region between these two areas, a liquid crystal layer was observed. On the other hand, the materials used for artificial joints…(metal and polyethylene, which are now in use, and polyvinyl alcohol‐hydrogel polymer which is being developed), did not exhibit neither a clear fluid pool area nor the intermediary area with liquid crystal formation. These results suggest that natural articular cartilage surface has a particular characteristic which builds up a synovial pooling area and liquid crystal formation in the third area by interaction with macromolecules in synovial fluid under the loading condition. These characteristics give natural articular cartilage its excellent lubricative function. To improve the quality of artificial joints, the characteristics of the implant material surface and the synovial macromolecules must be considered.
Abstract: The aim of this research was to investigate the optimization of the geometry of an UHMWPE type of knee implant in the sagittal plane with minimum amount of wear. Finite element analysis has been used to analyze our proposed 780 models consisting of different design parameters. Maximum stress occurring in the whole tibial component, on the surface or subsurface of the plate, was considered as a design parameter to evaluate the wear condition. By avoiding the small contact area and high stresses in the tibial part, the maximum safe flexion angles have been determined. Other effective design factors such as…implant stability, roll back distance, patella lever arm, and minimum bone resection have also been considered. Taking into account the variable parameters in the geometry of the implant parts, all possible models for the femoral component, which is made from metal, and the tibial component, which is made from UHMWPE, have been built in ANSYS and analyzed in the sagittal plane. By considering the effective mechanisms of wear in polyethylene, the results of the analyses were used to find the optimized geometry of a knee implant. This is the model, which is expected to experience the minimum wear, besides having some other properties of an ideal knee prosthesis.
Abstract: Hydroxyapatite (HA) was coated onto titanium substrates using radio frequency sputtering, and the coated HA films were crystallized in an autoclave at 110°C using a low temperature hydrothermal method. The crystallite size, the Ca/P ratio, and the surface of the films were observed using XRD, EDS, and SEM, respectively. An immersion test was carried out in physiological saline solution, and the film‐to‐substrate adhesion strength was measured using a pull‐out test. From the XRD patterns, a sputtered film subjected to the hydrothermal treatment had crystallized after 24 h, and the crystallite size increased from 38.0±8.7 to 81.4±19.1 nm. In immersion tests,…an as‐sputtered film completely dissolved after 1 d, whereas a sputtered film subjected to the hydrothermal treatment survived to 18.7±5.8% of the initial film thickness after four weeks. In pull‐out tests, the adhesion strength of the sputtered film to the substrate increased from 1.9±0.2 to 5.3±1.6 MPa after the hydrothermal treatment. A sputtered film subjected to the hydrothermal treatment and a plasma‐sprayed coating on titanium columns were implanted in the diaphysis of the femora of six adult dogs, and a pull‐out test was carried out after two, four, and 12 weeks. The sputtered film showed higher bone bonding strength than the plasma‐sprayed coating at any period.
Keywords: Sputtering, hydroxyapatite, crystallization, hydrothermal, bone bonding strength