Bio-Medical Materials and Engineering - Volume 8, issue 2

Authors: Van Moorleghem, W. | Chandrasekaran, M. | Reynaerts, D. | Peirs, J. | Van Brussel, H.

Article Type: Research Article

Abstract: Shape memory and superelasticity are novel properties not exhibited by common materials. In recent years, these properties and the alloys exhibiting them have found widespread use as new medical materials, in devices such as diagnostic and therapeutic catheters of different kinds, stents, needle wire localisers, orthodontic arch wires, implantable drug delivery system etc. The reasons for this trend and the future potential of these materials in medical applications will be explained in this presentation.

Keywords: Shape memory, superelasticity, Ni–Ti, bio‐acceptance, corrosion resistance

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 2, pp. 55-60, 1998

Authors: Chen, Guanfu | Wen, Xuejun | Zhang, Ning

Article Type: Research Article

Abstract: In vitro corrosion resistance and ion dissolution of commercial pure titanium with different surface microroughness are studied adopting constant potential meter and atomic absorption spectroscopy. In terms of the surface roughness, titanium samples are divided into 5 groups: smooth surface, machining surface, 2 different microroughness surfaces and macrorough surface. Each group contains three category samples under different treatments: natural oxidation (24 h exposure to air), oxidation under 400^{\circ} C (400^{\circ} C, 45 min thermal oxidation), oxidation under 700^{\circ} C (700^{\circ} C, 45 min thermal oxidation). In Hanks corrosion media, comparative studies through constant potential anode polarization …curves and titanium release rates of the 5 groups of Ti samples demonstrates that oxidation under 400^{\circ} C best increase corrosion resistance and decrease ion release sharply, oxidation under 700^{\circ} C is better than natural oxidation. Ti samples with a different surface roughness all have good corrosion resistance and their corrosion resistance drop with the raising of surface roughness. Comparing with macrorough surface and machining surface, microrough surfaces have better corrosion resistance and a lower ion release rate which are similar to those of smooth surfaces. Moreover, the corrosion resistance of machining surface Ti is the lowest. It is hypothesized that surface treatment methods such as surface thermal oxidation, surface aging and so on will improve the corrosion resistance and decrease the ion release rate of rough surface effectively by increasing the thickness of surface protection film, improving its structural uniformity and facilitating the formation of ordered, compact surface protection film. Show more

Keywords: Electrochemistry, corrosion resistance, in vitro test, ion release, microrough surface, titanium, thermal oxidation

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 2, pp. 61-74, 1998

Authors: Gu, Zheng‐Qiu | Xiao, Jiu‐Mei | Zhang, Xiang‐Hong

Article Type: Research Article

Abstract: Aqueous poly(vinyl alcohol) solutions were frozen at -20^{\circ} C for 6–12 h, and subsequently thawed for 1–2 h. The above mentioned process repeated for 1–3 times. After the specimen was dehydrated in vacuum, a kind of artificial articular cartilage – PVA‐hydrogel – was developed. The micromorphology of PVA‐hydrogel has been observed by means of optical microscopy and SEM. DSC and mechanical tests have been empolyed to investigate the influence of freezing, thawing, dehydrating and irradiating upon the crystallinity and the mechanical properties of PVA‐hydrogel.

Keywords: Artificial articular cartilage, PVA‐hydrogel, repeated freezing–thawing , dehydrating in vacuum, cross‐linking by irradiation

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 2, pp. 75-81, 1998

Authors: Yamamoto, Noritaka | Hayashi, Kozaburo

Article Type: Research Article

Abstract: The tensile properties of the rabbit patellar tendon were determined at a very high extension rate (560 mm/s), and were compared to those obtained at lower rates (53 and 0.33 mm/s). A closed‐loop servo‐hydraulic material test machine was used for the tensile tests at the rates of 560 and 53 mm/s. Strain was determined using a high‐speed video dimension analyzer consisting of a line sensor camera, control unit, and image processing board. For the tests at 0.33 mm/s, a conventional tensile tester and video dimension analyzer were utilized. The tensile strength and strain at failure of the tendon increased by …51 and 77%, respectively, with increase in the extension rate from 0.33 to 560 mm/s (from 0.566 to 1250%\, s^{-1} in strain rate); these parameters increased by 35 and 42%, respectively, with the rate change from 0.33 to 53 mm/s (from 0.566 to 151%\, s^{-1} ). However, there were no significant differences in the tangent modulus among the three rates. These results indicate that tensile strength and strain at failure increase with increase in strain rate, with no change in tangent modulus. Show more

Keywords: Mechanical properties, patellar tendon, tensile test, high strain rate, rabbit

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 2, pp. 83-90, 1998

Authors: Lewis, Gladius

Article Type: Research Article

Abstract: It is now widely accepted that both the design and the operating conditions at articular surfaces in total joint replacements influence the magnitude of the contact stress at those surfaces. In turn, such stress plays a pivotal role in the clinical performance of the prosthesis. Hence, a plethora of methods have been used by many workers not only to determine or estimate this stress but also to identify the main influencing factors. This literature is critically reviewed in the present study, which is in two parts. In this first part, the focus is on experimental methods. Two main recommendations emerge …from this review. First, the pressure‐sensitive film should be used. Second, more work is needed in many areas, an example of which is the effect of the method of sterilization of tibial inserts on the contact stress at the tibiofemoral interface in knee implants. Show more

Keywords: Contact stress, pressure‐sensitive film, resistive ink sensor, photoelasticity, joint replacements

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 2, pp. 91-110, 1998

Authors: Ranu, Harcharan Singh

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 8, no. 2, pp. 111-118, 1998