Bio-Medical Materials and Engineering - Volume 10, issue 3-4
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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: We have recently developed a new‐type trapezoid mesh cage (TPM cage) together with an insertion device, which for use as a new titanium mesh intervertebral spacer in posterior lumbar interbody fusion (PLIF). The TPM cage has sufficient mechanical strength, a large contact area that gives good long‐term stability, and preserves the initial disc height to provide good balance. The insertion device for the TPM cage is useful not only for handling the implant but also for controlling the implant insertion direction. The TPM cage and its insertion device are promising for use in PLIF.
Abstract: Along with the rapid development of information technology, computers play an increasingly prominent and important role. One current trend is to use computers as instruments for physical rehabilitation. In this study, we introduce a new hand motion assessment and rehabilitation system. This system assesses a user's grip strength and records the sudden changes in air pressure through a circuit and A/D adapter. A PC interface transforms and saves the data in a data record file. The data is then compiled and combined with a patient's case history and keyed into a database as reference for clinical use. The system is…highly efficient, cheap and convenient to use. Doctors can use it to monitor and analyze the progress of a rehabilitation program.
Keywords: Rehabilitation, dynamometer, hand motion, assessment
Abstract: In cemented acetabular cup design it is acknowledged that bone resorption and fatigue fracture of cement may cause the most common problems after total hip replacement. Previous studies have optimized the shape of metal backing (MB) shell used in cemented acetabular components in order to minimize the fatigue notch factor (Kf ) in cement, whilst at the same time maximizing Kf in bone at the central part of acetabulum to prevent stress shielding and subsequent bone resorption . The optimal shape was found to be thin at the edges and thick at the dome. The present study describes…the effect of changing the elastic modulus of the backing material on Kf and stresses as predicted by the initial shape of the backing shell of (3 mm) thick, and the optimized backing shape of non‐uniform thickness in order to find the optimal material for the backing shell. It is recommended to use a backing shell material with elastic modulus equals 70 GPa (which can be readily attained using a fiber reinforced polymer composite). It is shown that such a material will decrease the fatigue notch factor and the stresses in cement at cup edges, at the same time it will increase the stresses and the fatigue notch factor in bone at the central part of acetabulum. Thereby, reducing the possibility of fatigue fracture of cement, whilst at the same time decreasing the stress shielding effect and the resulting bone resorption. The effect of lower bone resorption and lower probability of fatigue fracture of the cement will also reduce the incidence of loosening and premature revision operations.
Keywords: Von Mises stresses, elastic modulus, fatigue notch factor, bone resorption, finite element analysis
Abstract: The present review contains salient features of the most widely used methods for depositing hydroxyapatite (HA) coatings on bioalloy substrates. These methods range from the ubiquitous plasma spraying in air to the recently introduced ion beam enhanced deposition technique. Special attention is paid to the residual stress in the coating that arises from various sources and whose magnitude impacts the adhesion of the coating to the substrate and, hence, the efficacy of the coated part (see, for example, the in vivo performance of HA‐coated orthopaedic and dental implants). Thus, the plethora of methods for estimating residual stresses in HA‐coated systems…are critically examined. The review concludes with a detailed presentation of ten areas for future research work.
Abstract: The present study evaluates the effectiveness of specialised biomaterials consisting of clove oil‐ phospholipid mixtures as possible substitute surfactants in diseases of altered mucus viscosity by studying their effect on the viscosity of mucus gel simulants in vitro. Test surfactants consisting of phospholipid‐clove oil mixtures in the ratio of 1 part of oil to 9 parts of phospholipid were prepared. The phospholipids used were dipalmitoyl phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) and binary mixtures of PC : PE and PC : PG in the ratio of 2 parts of PC to 3 parts of PE or PG. The effects of the phospholipid‐clove oil…mixtures on the viscosity of mucus gel simulant (MGS: a polymeric gel consisting predominantly of gum tragacanth and simulating respiratory mucus), was studied by application of steady shear rates ranging from 0.512 to 51.2/s in a concentric cylinder viscometer at 37○ C. The change in MGS viscosity, after incubation with surfactants, was found to have a non‐Newtonian character and to follow the power law model with R2 values >0.8. The addition of clove oil‐phospholipid mixtures caused a decrease in the MGS viscosity when compared with the effect of the phospholipid alone at low shear rates in case of PC, PG and PCPG. The combination of PC : PG with clove oil caused ratios of change in MGS viscosity <1 i.e., caused a decrease in the MGS viscosity. PC : PG with clove oil was capable of lowering MGS viscosity and should be further researched as possible therapies for diseases of altered mucus rheology.
Keywords: Surfactant, clove oil, mucus gel simulant viscosity
Abstract: We developed a poly‐L‐lactide material strengthened by a highpressed extrusion technique. The bending strength of a rod made of that material is higher than that of the same size rods made of poly‐L‐lactide strengthened by drawing technique, which has been used in clinical cases. The purposes of this study were, first to clarify if the initial strength of extrusion‐strengthened poly‐L‐lactide screws is higher than that of draw‐strengthened poly‐L‐lactide screws, and, secondly to investigate the safe torque for driving the screws in clinical usage. In accordance with AO screw design, five kinds of screws were manufactured. In a pull‐out test and…a twisting test using a DYRACON® blocks, the strength of the highpressed extrusion‐strengthened poly‐L‐lactide material was also higher than that of the draw‐strengthened poly‐L‐lactide material after milling into screws. In the simulation using minipig bones and the 4.5 mm∅ cortical screws, when the thickness was below 0.5 mm, between 0.5 and 2 mm or over 3 mm, the break locations were in the cortical bone, the thread of the screw and the under head fillet respectively. In the simulation using minipig bones and the 4.0 mm∅ cancellous screws, breakage occurred not on the screws but on the cancellous bone in all screws.
Keywords: Poly‐L‐lactide, biodegradable, implant, mechanical test
Abstract: Hydrothermal method was used to prepare the hydroxyapatite (HA) coating on CaO‐SiO2 ‐B2 O3 ‐Na2 O glass. The phase composition, morphology and microstructure of HA coated glass composites were analyzed using XRD, EPMA, FT‐IR and SEM techniques. It revealed that HA coating possessed a porous gradient construction; HA coating was tightly bonded with the glass substrate by the interface layer. During the formation of HA coating, the hydrated silica produced by the corrosion of glass substrate in the hydrothermal solution provided favorable sites for apatite nucleation. With the dissolving of HA powder and the growth of apatite small crystallites, Ca2+…, PO4 3− ions would precipitate on the surface of glass to form the HA coating. Silicon element released from glass reacted with calcium produced by the dissolution of HA to form the tight reaction layer. HA coating is formed by the mechanism of dissolving‐ions immigrating‐precipitating pattern.
Abstract: Hydroxyapatite (HA) coated CaO–SiO2 –B2 O3 –Na2 O glass composites prepared by a hydrothermal coating method were soaked in four kinds of solutions to evaluate the dissolution behavior and the chemical stability. 0.5 mol/l HCl and 0.5 mol/l HNO3 were used as acidic solution, and 5% physiological saline and sodium lactate compound solution as the neutral physiological solution. It was found that HA coated glass composites had the better chemical stability and the corroding‐resistance ability. The dissolution behavior of the HA coating was mainly correlated with the phase composition of the as‐received HA coating and its microstructure as well…as the pH value of the solution.
Keywords: Hydroxyapatite coating, hydrothermal method, dissolution behavior, chemical stability, acidic solution, simulated body fluid
Abstract: Crystalline hydroxyapatite (HA) powder was coated on titanium substrate by radio frequency (RF) magnetron sputtering. The coating was homogeneous thin film and the thickness was 1μm. Crystallinity of the HA coating was low and Ca/P ratio was high as 3.0. Particle sizes were 40∼100 nm, and the crystallite size was calculated by 30∼50 nm using an X‐ray diffractometry (XRD) and a transmission electron microscopy (TEM). When the coating was heated at 800○ C for 1 h, the low crystalline HA grew up crystalline HA, and a diffraction pattern of CaO appeared. When the coating was immersed in pH 7.4 of…bovine serum for 1 week, c‐axis of HA increased.
Abstract: The response of primary murine macrophages and the U937 human histiocytic cell line to challenge with clinically relevant UHMWPE wear debris of known particle size and dose was evaluated. Particles with mean sizes of 0.24, 0.45, 1.71, 7.62 and 88 μm were co‐cultured with cells for 24 hours prior to assessment of cell viability and production of the osteolytic mediators IL‐1β, IL‐6, TNFα and, in supernatants from murine phagocytes, PGE2 and GM‐CSF. All particle fractions were evaluated at particle volume (μm3 ) to cell number ratios of 10 : 1 and 100 : 1 (and, additionally, 0.1 : 1…and 1 : 1 for U937 cells). These ratios had previously been identified as the most stimulatory and clinically relevant. Although the results for the cell line were highly variable, stimulation with phagocytosable particles (range 0.1 to 15 μm) resulted in enhanced levels of cytokine secretion by both murine macrophages and U937 histiocytes. The most biologically active particles were sub‐micrometre in size. However, U937 cells responded to wear debris at much lower particle volume to cell number ratios (>0.1 μm3 per cell) than the murine cells (>10 μm3 per cell). No GM‐CSF was produced by particle or LPS stimulated murine macrophages. Similarly, U937 histiocytes failed to secrete any IL‐1β. Neither macrophage population responded to stimulation with the largest (88 μm) particles. These results confirm earlier findings and suggest that the size of UHMWPE wear particles is a critical factor in macrophage activation. Moreover, primary murine macrophages have been demonstrated to be a suitable model for studying cell‐particle interactions in vitro.
Abstract: This paper describes the design of a pin on plate rig which has been modified to give multi‐directional motion to the test pins, resulting in elliptical and quasi‐elliptical wear paths. Such paths are closer to those seen in vivo by a femoral head articulating against an acetabular cup. The description of the rig is augmented by the results of a test of ultra high molecular weight polyethylene pins rubbing against stainless steel plates, with dilute bovine serum at 37○ C being used as the lubricant. With standard reciprocating motion, a mean wear factor of 0.085 × 10−6 mm3 /N m…was found, but with multi‐directional motion, the mean wear factor increased to 1.10 × 10−6 mm3 /N m, which is very similar to in vivo wear factors.