Bio-Medical Materials and Engineering - Volume 9, issue 1

Authors: Assad, M. | Lemieux, N. | Rivard, C.H. | Yahia, L’H.

Article Type: Research Article

Abstract: The genotoxicity level of nickel‐titanium (NiTi) was compared to that of its pure constituents, pure nickel (Ni) and pure titanium (Ti) powders, and also to 316L stainless steel (316L SS) as clinical reference material. In order to do so, a dynamic in vitro semiphysiological extraction was performed with all metals using agitation and ISO requirements. Peripheral blood lymphocytes were then cultured in the presence of all material extracts, and their comparative genotoxicity levels were assessed using electron microscopy‐in situ end‐labeling (EM‐ISEL) coupled to immunogold staining. Cellular chromatin exposition to pure Ni and 316L SS demonstrated a significantly stronger gold binding …than exposition to NiTi, pure Ti, or the untreated control. In parallel, graphite furnace atomic absorption spectrophotometry (AAS) was also performed on all extraction media. The release of Ni atoms took the following decreasing distribution for the different resulting semiphysiological solutions: pure Ni, 316L SS, NiTi, Ti, and controls. Ti elements were detected after elution of pure titanium only. Both pure titanium and nickel‐titanium specimens obtained a relative in vitro biocompatibility. Therefore, this quantitative in vitro study provides optimistic results for the eventual use of nickel‐titanium alloys as surgical implant materials. Show more

Keywords: Nickel‐titanium, biocompatibility, genotoxicity, electron microscopy, nickel release

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 1, pp. 1-12, 1999

Authors: Todo, Shinichi | Tomita, Naohide | Kitakura, Takahiro | Yamano, Yoshiki

Article Type: Research Article

Abstract: The objective of this study was to evaluate the effect of sliding locus on fatigue destruction of ultra‐high‐molecular‐weight polyethylene (UHMWPE) in order to design a durable total knee arthroplasty (TKA) articulation. Two‐dimensional sliding fatigue testing was performed under two simplified patterns of articulating interface sliding locus. Scanning acoustic tomography (SAT) was used for observation of subsurface cracks in UHMWPE specimens. A high rate of subsurface crack formation was observed when the movement was reciprocated on two different loci, in contrast with that on a single linear locus. This finding suggests that crack formation or propagation in UHMWPE components is accelerated …not only by the compressive stress but also by complicated articulating movement locus. Show more

Keywords: UHMWPE, delamination, fatigue, wear, artifcial knee joint

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 1, pp. 13-20, 1999

Authors: Nordström, E. | Ohgushi, H. | Yoshikawa, T. | Yokobori, Jr., A.T. | Yokobori, T.

Article Type: Research Article

Abstract: In order to investigate the significance of hydroxyapatite based microporous composite (HA/mica composite) surfaces and a macroporous synthetic hydroxyapatite, rat marrow cell culture, which shows osteogenic differentiation, was carried out on six different culture substrata (two control culture dishes, two identical HA/mica composites, and two identical macroporous synthetic hydroxyapatites). A culture period of two weeks in the presence of \beta ‐glycerophosphate (BGP), ascorbic acid, and dexamethasone resulted in abundant mineralized nodule formations that were positive for alkaline phosphatase (ALP) stain. The stain on the macroporous synthetic hydroxyapatite and the HA/mica composites were intense, the enzyme activity being about …double that of control culture dishes. These data indicate that the synthetic macroporous hydroxyapatite surface and the HA/mica composite surface promotes osteoblastic differentiation. Show more

Keywords: Hydroxy(l)apatite, ceramic composite, cell culture

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 1, pp. 21-26, 1999

Authors: Maiman, Dennis J. | Kumaresan, Srirangam | Yoganandan, Narayan | Pintar, Frank A.

Article Type: Research Article

Abstract: The biomechanical effects of superior (C4‐C5) and inferior (C5‐C6) level fusions with different graft materials on the adjacent unaltered components were quantified using an anatomically accurate and experimentally validated C4‐C5‐C6 finite element model. Smith‐Robinson and Bailey‐Badgley fusion procedures were analyzed with five different types of interbody fusion materials with varying stiffnesses. Intact and surgically altered finite element models were subjected to physiologic compression, flexion, extension and lateral bending. The external axial and angular stiffness, and the internal unaltered intervertebral disc (C5‐C6 for the superior and C4‐C5 for inferior fusion) and C5 vertebral body stresses were determined. The superior level fusion …resulted in the highest increase in external response in lateral bending for all implant materials in both surgical procedures. In contrast, the inferior level fusion produced a higher increase in the C4‐C5 disc and C5 vertebral body stresses in compression than the superior level fusion in both surgical procedures. The increased internal stress responses reflecting the changes in the load‐sharing following inferior level fusion may explain clinical observations such as enhanced degeneration subsequent to surgery. Because of the inclusion of three levels in the present multi‐segment finite element model, it was possible to determine these responses in the unaltered adjacent components of the cervical spine. Show more

Keywords: Biomaterial, biomechanics, finite element model, spinal implants, cervical spine

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 1, pp. 27-38, 1999

Authors: Torrisi, L.

Article Type: Research Article

Abstract: The main properties of NiTi alloys are presented, discussed and compared with respect to those of stainless steels. Special regard is given to the use of NiTi alloy as orthodontic wires and endodontic instruments. The superelastic properties of orthodontic wires and endodontic files are measured as a function of the applied stress, of the strain and of the temperature. Both biomedical devices are submitted to surface analysis to control the interface with the biological environment in which they will be immersed.

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 1, pp. 39-47, 1999

Authors: Khang, Gilson | Cho, Jin Cheol | Lee, Jin Whan | Rhee, John M. | Lee, Hai Bang

Article Type: Research Article

Abstract: Japanese encephalitis virus (JEV) vaccine loaded biodegradable poly(L‐lactide‐co‐glycolide) (PLGA) microspheres (MSs) were prepared by W/O/W solvent evaporation method to study the possibility for oral vaccination. The influence of several preparation parameters as stirring rate, types and concentration of emulsifier, PLGA concentration, etc. has been observed on size, size distribution and biodegradation. The mean MSs size decreased when the agitation speed and the concentration of emulsifier were increased, and when the PLGA concentration was decreased. The surface morphology of porous and nonporous JEV vaccine loaded PLGA MSs was prepared from polyvinylalcohol and sodium dodecyl sulfate as used emulsifiers, respectively. From the …assay of lactic acid and scanning electron microscope observation, it can be suggested that the rate of biodegradation of nonporous MSs was slower than that of porous surface morphology due to lower the surface area. Mechanisms of the formation of porous and nonporous surface by different types of emulsifier, and the biodegradation of MSs have been proposed. Also, the size and size distribution of JEV vaccine loaded PLGA MSs were discussed to apply oral vaccination through the Peyer’s patches across the gastrointestinal tract. Show more

Keywords: Japanese encephalitis virus vaccine, poly(L‐lactide‐co‐glycolide) microsphere, oral vaccine, porous and nonporous surface, W/O/W method

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 1, pp. 49-59, 1999

Authors: Huang, Shyh‐Chour

Article Type: Research Article

Abstract: An efficient method for gross motion simulation of human head/neck dynamics under the action of external forcing and high acceleration environments is presented. The system is composed of a serial of linked rigid bodies simulating the skull, vertebrae and torso. These bodies are connected to each other by nonlinear springs and dampers representing the physical features of disks, ligaments, and muscles. A systematic method for handling the geometry and kinematics is used to develop the model. The developed governing equations of the multibody system are useful for the development of numerical algorithms. Results show excellent agreement between the model and …the experiments. The model is expected to be useful for efficient analysis of head/neck dynamics during high acceleration environments and use with whole human body simulator. The results of several examples are also presented. Show more

Keywords: Head/neck system, modeling, multibody system

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 1, pp. 61-71, 1999