Bio-Medical Materials and Engineering - Volume 9, issue 2

Authors: Watarai, Mikiko | Hanawa, Takao | Moriyama, Keiji | Asaoka, Kenzo

Article Type: Research Article

Abstract: The current density of Ti‐56mass%Ni (Ti‐50at.%) alloy after abrasion in simulated bioliquids was measured using a potentiostat to estimate the amount of metallic ions released from the alloy during repassivation and maturation. The current density in saline, saline with and without N_{2} bubbling, and Hanks’ solutions with and without proteins after abrasion was measured and the amount of released ion was calculated from the integrated current density with time, assuming that Ti^{4+} and Ni^{2+} are equivalently released. No difference in the amount of released ion was observed between saline with and without N_{2} …bubbling. Also, no difference was observed between saline and pH 7.4 Hanks’ solution. More Ti^{4+} and Ni^{2+} were released in bioliquids with proteins than in saline with and without N_{2} bubbling (p<{} 0.05). That is, dissolved oxygen and inorganic ions in Hanks’ solution did not influence the amount of released ion, but proteins influenced it. The release of metallic ions from metals and alloys in biological systems can be estimated by the methodology employed in this study. Show more

Keywords: Titanium‐nickel alloy, current density, metallic ion release

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 2, pp. 73-79, 1999

Authors: Valdevit, Antonio | Ortega‐Garcia, Jose | Kambic, Helen | Kuroda, Ryosuke | Elster, Theodore | Parker, Richard D.

Article Type: Research Article

Abstract: Data regarding intra‐joint loads during range of motion is essential to understanding normal joint mechanics and pathology. The investigators configured and characterized the response of a 440 N range, 0.076 mm thick commercial thin film sensor to monitor joint loads through a range of motion. Following preconditioning, static and dynamic tests were performed to evaluate the sensor response under varied environmental conditions. Both tests utilized a fixture to align the sensor and applied load. Under conditions that included dry, wet, folded and kinked configurations, a static load of 100 N was applied and the sensor output monitored up to thirty …minutes from the time of loading. A load of 400 N at 50 N/s was applied to the sensor to determine dynamic characteristics and calibration curves under the conditions described for static tests in addition to curved, hard and soft contact surfaces and sensor overload. Static kinked data was significantly different from the dry, wet and folded conditions. Dynamic data showed that inter‐package variability was not significant but that differences between sensor packages and sensor configuration conditions were significant. To investigate applicability of these sensors to the field of orthopaedics, a cadaveric knee was instrumented with sensors to examine the role of the meniscus in load transmission and distribution across the knee. The sensors were placed bilaterally below each meniscus on the anterior, posterior and center of the tibial plateau. Sensor data were obtained at these locations during manually flexed range of motion for the intact, re‐attached and lateral menisectomized conditions of the knee specimen. Show more

Keywords: Sensor, joint loading, characterization, transducer, pressure

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 2, pp. 81-88, 1999

Authors: Kim, D.G. | Shin, M.J. | Kim, K.H. | Hanawa, T.

Article Type: Research Article

Abstract: Immersion treatment of titanium in aqueous solutions containing various kinds of ion concentrations of calcium and phosphate (pH 5.8, 7.0, and 8.0) were attempted to accelerate calcium phosphate precipitation on titanium in body fluid. The performance was confirmed using scanning electron microscopy, X‐ray diffractometry, and Fourier transformed infrared absorption spectrometry with a reflection absorption spectrometer of the specimen immersed in Hanks’ solution. Calcium phosphate precipitation on titanium in Hanks’ solution is accelerated by the immersion treatment in aqueous solutions containing calcium and phosphate ions. The amount, composition, and shape of calcium phosphate precipitate vary according to the pH and ion …concentrations of the solutions in which titanium is immersed. This method is effective for the surface treatment of inside pore narrow space of titanium materials. Show more

Keywords: Titanium, surface treatment, immersion, calcium phosphate precipitation

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 2, pp. 89-96, 1999

Authors: Tanaka, M. | Hirano, K. | Goto, H. | Namima, T. | Uchi, K. | Jiang, Z.W. | Matsuki, H. | Tanahashi, Y. | Orikasa, S. | Chonan, S.

Article Type: Research Article

Abstract: This paper is concerned with the development of an artificial urethral valve driven by shape memory alloy actuators, which is attached onto the urethra of a urinary incontinence sufferer for treating the involuntary micturition. Three types of compact cylindrical valves are assembled and their opening and closing functions are examined experimentally. The updated valve is heated and opened by using the transcutaneous energy transformer consisting of a pair of flexible spiral‐formed copper wire coils. The experiment using the canine urinary canal verifies that the total system of the valve and the transformer works well as an artificial sphictor muscle and …controls the urinary flow through the canal appropriately. Show more

Keywords: Urinary incontinence, artificial urethral valve, shape memory alloy, animal experiment, transcutaneous transformer

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 2, pp. 97-112, 1999

Authors: Endo, M.M. | Barbour, P.S.M. | Barton, D.C. | Wroblewski, B.M. | Fisher, J. | Tipper, J.L. | Ingham, E. | Stone, M.H.

Article Type: Research Article

Abstract: The wear debris generated from UHMWPE (ultra high molecular weight polyethylene) has been recognised as one of the major causes of failure in THR (total hip replacement). GUR 1120 (compression moulded) and GUR 4150HP (ram extruded) which are currently the most frequently used materials in THR were studied in pin‐on‐plate wear test. The wear particles generated from this test were observed by scanning electron micrograph and analysed by image analysis. The results from this study showed that GUR 4150HP had superior wear resistance than GUR 1120 under relatively high wear factor conditions. These results also highlighted the importance of multidirectional …motion and its effect on the wear rates of UHMWPE. The multidirectional motion tended to show a higher wear factor than previous studies using unidirectional motion conducted under otherwise similar conditions. The wear debris analysis conducted with the wear particles collected from unidirectional (relatively rough) pin‐on‐plate wear tests (GUR 1120 and GUR 4150HP) showed that the greatest number of particles had a size range of 0.1–0.5 \mu m followed by 0.5–1.0 \mu m, 1.0–5.0 \mu m and 5.0–10.0 \mu m, in both GUR 1120 and GUR 4150HP. However, comparing the masses of the wear particles, the bigger size range of greater than 10 \mu m, had the highest percent mass followed by 1.0–5.0 \mu m, 0.5–1.0 \mu m, 0.1–0.5 \mu m and 5.0–10.0 \mu m. Show more

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 2, pp. 113-124, 1999

Authors: Oshida, Y. | Gorthy, J.

Article Type: Research Article

Abstract: Water sorption tests were conducted on unfilled poly(methyl methacrylate) samples in distilled water at 5, 37, and 60\,^{\circ} C under three different tensile stress ratios (\sigma_{\rm appl}/\sigma _{\rm ys}= 0 %, 5%, and 10%). Each sample was placed in a modified Hoffman open‐side tubing clamp and subjected to four‐point bending at pre‐determined stress level for 1 day, 3 days, 1 week, 2 weeks, and 4 weeks. Water sorption was measured by weight change calculations, without accounting for any weight loss due to solubility of uncured monomer. A generalized diffusion equation can be used to express both stress‐free and …stress conditions; D=D_{\rm o}\exp[-E(\sigma)/kT] . It was found that the activation energy for water sorption diffusion was linearly related to applied stress ratios; i.e., E=1.15\ \sigma_{\rm appl}/\sigma_{\rm ys} + 10.76 (kJ/mol), with the correlation coefficient r =0.97 . Since the proportional pre‐exponential constant, D_{\rm o} , is independent of temperature, it is speculated that the loading percentage of reinforcing filler elements in composite resin materials can be related to this constant. Show more

Keywords: Water‐sorption, diffusion kinetics, poly(methyl methacrylate) resin, activation energy, stress ratio

Citation: Bio-Medical Materials and Engineering, vol. 9, no. 2, pp. 125-133, 1999