Bio-Medical Materials and Engineering - Volume 11, issue 4

Authors: Saxena, Amulya K. | Willital, Günter H. | Vacanti, Joseph P.

Article Type: Research Article

Abstract: Medical science continues to battle against the loss or failure of organs or tissues. Since, skeletal muscle loss lead not only to the functional compromise of the affected site, but also a structural deformation; tissue engineering of skeletal muscle attempts to provide solutions to replace loss of tissue contour and function. In our study, myoblasts seeded onto polyglycolic acid (PGA) meshes were used to engineer skeletal muscle tissue in vivo. The cell–polymer constructs harvested after a period of 6‐weeks were well vascularized three‐dimensional structures with the ability to generate neo‐muscle‐like tissue. This is the first time that the ability of …myoblasts to survive in vivo in the absence of mature skeletal muscle tissue was demonstrated. The successful ability to transplant myoblasts using biodegradable polymer strands without using the traditional transplantation buffer mediums as carriers was also employed for the first time. Show more

Citation: Bio-Medical Materials and Engineering, vol. 11, no. 4, pp. 275-281, 2001

Authors: Mazeau, G. | Czernuszka, J.T.

Article Type: Research Article

Abstract: Hydroxyapatite has been rubbed against ultra‐high‐molecular‐weight‐polyethylene (UHMWPE) under calcium‐containg aqueous solutions. Further, hardness tests were carried out in air and in calcium‐containing solutions whose pH ranged from pH 5 to pH 9. Hardness was found to vary with pH with a peak at around pH 7, i.e. – a chemomechanical effect was observed. Wear tests consisted in sliding hydroxyapatite samples against a UHMWPE disk for eight hours when lubricated by the same solutions as those used for the hardness tests. Volume loss, pH and calcium concentration were measured for up to 8 hours of sliding. Linking wear tests results with …hardness results and supersaturation levels, it was concluded that two wear mechanisms occurred. A chemical mechanism depending on supersaturation occurred at the early stages of sliding. The wear rate was essentially independent of hardness during this stage. After a few hours, depending on the supersaturation of the lubricant, the chemical mechanism turned into a chemomechanical mechanism dependant on hardness. Show more

Keywords: Hydroxyapatite, wear, polyethylene, chemomechanical effects, chemical wear

Citation: Bio-Medical Materials and Engineering, vol. 11, no. 4, pp. 283-392, 2001

Authors: Hedia, H.S.

Article Type: Research Article

Abstract: Most of machine parts, artificial joints and their components used for human body contain fillets, which connects two different diameters or widths. These fillets may cause a failure for these components. So, in this paper an optimisation method is presented which calculates and predicts optimal shape of the longitudinal profile for transition length of a tension bar, which connects two different diameters, using the ANSYS program. This method is applied to maximise the crack initiation time by minimising the fatigue notch factor Kf . A specified program has been developed to calculate the fatigue notch factor using Ansys Parametric Design …Language (APDL) which is associated to the ANSYS Package. It was observed that the maximisation of crack initiation time with higher value of the statistical parameter, k, is also a minimisation of stress concentration factor, kt , at the same time. A tension bar with four different transition length, t (t/d=0.333, 0.4167, 0.5 and 0.583) is considered. The crack initiation time of the optimal shape for all cases was increased by 17%, 12%, 9% and 7%, respectively. The stress concentration factor was reduced by 20%, 17%, 15% and 12.5%, respectively. Show more

Keywords: Stress concentration, crack initiation time, von Mises stress, finite element, optimisation

Citation: Bio-Medical Materials and Engineering, vol. 11, no. 4, pp. 293-300, 2001

Authors: Miyazaki, Hiroshi | Hayashi, Kozaburo

Article Type: Research Article

Abstract: Morphology and phagocytosis of macrophages were studied after cultured under cyclic strain. Peritoneal macrophages obtained from 6‐week old female C57BL/6J mice were attached to silicone rubber sheets, preincubated for 2 hours, and then cultured for 24 and 48 hours under cyclic strain of 5% amplitude and 1 Hz frequency (strained group) or no strain (non‐strained group). Control data were obtained from 0‐hour cultured cells (control group). Cell morphology was observed with optical and scanning electron microscopes, and shape index (SI) of each cell was determined from the perimeter and adhesion area. Phagocytotic activity was evaluated from the uptake of latex …particles 1.5 μm in diameter. The morphology and phagocytosis of macrophages were affected by cyclic strain, although the percentage of differentiated cells was not the case. SI in the strained group was smaller than that in the non‐strained group, and had a tendency of decreasing with time. Cyclic strain suppressed the phagocytosis of macrophages for latex particles, and there was a significant difference in the phagocytosis between the strained and the non‐strained groups after 24‐hour culture. Show more

Citation: Bio-Medical Materials and Engineering, vol. 11, no. 4, pp. 301-309, 2001

Authors: Park, K.D. | Khang, G.S. | Lee, H.B. | Park, J.B.

Article Type: Research Article

Abstract: Considered one of the weak links in the total hip replacement (THR), efforts to enhance the interfacial strength between bone cement and ultra‐high molecular weight polyethylene (UHMWPE) acetabular cup had been conducted in this laboratory. Following the successful demonstration of high interfacial strengths for our new acetabular component design, the nature of physical, chemical, and thermal property of the compression‐molded specimens, including UHMWPE, PMMA/MMA treated UHMWPE, and PMMA has been investigated in this study. Density results from a density gradient column showed that the molding processes and conditions were adequate for complete sintering of UHMWPE and PMMA powders. FTIR‐ATR results …gave a direct evidence that PMMA did exist in the PMMA/MMA treated UHMWPE matrix. It also revealed a clear diffusion‐related behavior across the interface. Under the high temperature and pressure, the UHMWPE powders undergo drastic changes of their morphology and crystalline structures. These changes were examined by differential scanning calorimeter (DSC) which showed a large difference in terms of % crystallinity. The percent of PMMA deposited in the treated UHMWPE was 17.8%, 18.8%, and 24.3% from the analyses of density, FTIR‐ATR, and DSC, respectively. Finally, an evidence of diffusive behavior at the interface exhibited diffusion of PMMA occurring across the interfaces between the treated UHMWPE and UHMWPE or PMMA. Show more

Keywords: PMMA pre‐coated UHMWPE, density, FTIR‐ATR, DSC, diffusion

Citation: Bio-Medical Materials and Engineering, vol. 11, no. 4, pp. 311-323, 2001

Authors: Lim, Young Jun | Oshida, Yoshiki

Article Type: Research Article

Abstract: The cell attachment to bioapplicable titanium surfaces is an important parameter in the area of clinical implant dentistry and medicine. A major consideration in designing implants has been to produce surfaces that promote desirable responses in the cells and tissues contacting the implants. In this study, three titanium materials (commercially pure titanium – CPT –, Ti‐6Al‐4V, and TiNi) were treated mechanically, chemically, mechano‐chemically, and thermally to produce concave surfaces with varying roughness. Using four media (distilled water, 1% NaCl aqueous solution, a suspension of human neutrophils, and a suspension of the MG‐63 osteoblast‐like cells), the initial contact angles were measured. …Six readings (three drops each measured by two observers) were collected for each material and for each medium. The interclass correlation coefficients were used for the group comparisons. A one‐way analysis of variance (ANOVA) and Tukey's HSD (honestly significant difference) statistical analyses were employed. It was found, for CPT, that (1) statistically, there were no significant differences among four media in contact angles, (2) the contact angle increased linearly with average roughness when the angles were higher than 45 degrees, and (3) the contact angle decreased linearly with roughness when the angle was less than 45 degrees. Show more

Keywords: Contact angle, surface concave roughness, neutrophil, osteoblast‐like cell, titanium, titanium alloys

Citation: Bio-Medical Materials and Engineering, vol. 11, no. 4, pp. 325-341, 2001

Article Type: Research Article

Citation: Bio-Medical Materials and Engineering, vol. 11, no. 4, pp. 343-343, 2001

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 11, no. 4, pp. 345-348, 2001

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 11, no. 4, pp. 349-350, 2001