Bio-Medical Materials and Engineering - Volume 6, issue 5

Authors: Lee, D.H. | Ko, R.K. | Cho, Z.H. | Kim, S.S.

Article Type: Research Article

Abstract: The swelling process is often observed in many polymers of interest and is an important phenomenon for the understanding of many biopolymers. This important process, however, is known as poorly understood in the area in polymer science. One of the reasons is. that the conventional method of examining the swelling process is often inconsistent. Since it has many important properties including non-invasiveness, Nuclear Magnetic Resonance (NMR) Micro-imaging has become a significant method of analyzing biomaterials as well as biological specimens [1,2]. In the present study, a time-dependent swelling process was observed non-invasively to investigate the polymeric swelling effect using NMR …micro-imaging. The present study provides a noble and non-invasive method of measuring the degree of swelling as well as volumetric changes occurring in polymers immersed in liquid. The information obtained relates to both a water ingress process and volumetric changes of polymer specimens. This proposed method also will provide more reliable techniques to ascertain the time-dependent swelling process than the other conventional methods. One of the important aspects of the present study is that the proposed method is a non-invasive technique and is also capable of ascertaining the time-dependent process of the swelling. This may be a new method of measuring the degree of swelling as well as the time-dependent water ingress process in a polymer. Show more

Keywords: Swelling effect, NMR imaging, non-invasive method, time-dependent process, water ingress process

DOI: 10.3233/BME-1996-6501

Citation: Bio-Medical Materials and Engineering, vol. 6, no. 5, pp. 313-322, 1996

Authors: Khang, Gilson | Lee, Hai Bang | Park, Joon B.

Article Type: Research Article

Abstract: In order to improve the resistance of gamma-radiation sterilization of polypropylene (PP), the formulations of the additives such as antioxidants, crosslinking agent, and trans-stilbene oxide (StO) have been carried out. The irradiated PP and ethylene-propylene copolymer samples with control and additives were characterized by mechanical tester, colorimetry, and Fourier transform infrared spectroscopy with total attenuated reflectance mode (FTIR-ATR). Crosslinking agent and StO formulated PP showed remarkable radiation resistance and minimum discoloration. Also, radiation resistance of ethylene-propylene copolymers with 3% of ethylene contents was better than that of PP homopolymers in the case of no additives. The proposed mechanisms of radiation …stabilization with additives are also discussed. Show more

Keywords: Gamma-radiation sterilization, polypropylene, additives, trans-stilbene oxide, yellow index

DOI: 10.3233/BME-1996-6502

Citation: Bio-Medical Materials and Engineering, vol. 6, no. 5, pp. 323-334, 1996

Authors: Khang, Gilson | Kang, Yoon H. | Park, Joon B. | Lee, Hai Bang

Article Type: Research Article

Abstract: The adhesion of polymethylmetacrylate (PMMA) bone cement and low density polyethylene (LDPE) substrate by means of corona discharge treatment are presented. The surfaces were characterized by water contact angle goniometer, Fourier-transform infrared spectroscopy in the attenuated total reflectance mode (FTIR-ATR), electron spectroscopy for chemical analysis (ESCA), and scanning electron microscopy (SEM) for surface morphology. The bonding strength between bone cement and LDPE with varying intensity of corona treatment was evaluated by a 180° peel test. The water contact angles decreased with increasing treatment intensity from 95.0 ± 1.8 to around 43.5°. It was observed that the oxygen containing groups …as hydroxyl, ether, carboxylic acid, ester, ketone or aldehyde groups were introduced on the LDPE surfaces by corona treatment. The peel strength steeply increased from 0 to 1.75 kgf /cm with increasing the intensity of corona treatment. The improved adhesion of bone cement onto LDPE substrate may be due to only secondary force such as hydrogen bonding between PMMA bone cement and hydrophilized LDPE substrate. Show more

Keywords: Bond strength, bone cement, polyethylene, wettability, corona treatment, surface characterization

DOI: 10.3233/BME-1996-6503

Citation: Bio-Medical Materials and Engineering, vol. 6, no. 5, pp. 335-344, 1996

Authors: Yoshikawa, T. | Suwa, Y. | Ohgushi, H. | Tamai, S. | Ichijima, K.

Article Type: Research Article

Abstract: To investigate the feasibility of using self-setting hydroxyapatite cement as a carrier for marrow cells having a high osteogenic ability, a porous form of this cement was fabricated and combined with cultured marrow cells. Marrow cells were obtained from the femurs of a seven-week-old male Fischer 344 rat and cultured in Eagle's MEM containing 15% fetal bovine serum for ten days before being combined with the porous cement or with Interpore 200 hydroxyapatite as a control. The composites were subcutaneously implanted into syngeneic rats and harvested after six weeks. In both types of implants, active osteoblasts together with bone formation …were detected in contact with the pore surfaces. No cartilage formation was observed in any of the pores. Both types of implants with and without marrow cells caused very little foreign body reaction. These results indicate that self-setting hydroxyapatite cement containing marrow cells possesses a high osteogenic ability and may be useful as a bone graft substitute as well as a novel delivery system for bone-forming cells. Show more

Keywords: Self-setting hydroxyapatite cement, hydroxyapatite,, osteogenesis, marrow cell, in vivo

DOI: 10.3233/BME-1996-6504

Citation: Bio-Medical Materials and Engineering, vol. 6, no. 5, pp. 345-351, 1996

Authors: Lewis, Gladius

Article Type: Research Article

Abstract: Various pathologies, notably rheumatoid arthritis and/or trauma, are all known to cause severe pain and/or reduction of functional motion at the elbow joint. Implantation of a total arthroplasty, in such cases, has emerged as the first choice for management. For acceptable clinical performance, such an arthroplasty should be designed fully cognizant of various germane aspects of the anatomy, kinesiology and biomechanics of the normal joint. These aspects, together with a critical appraisal of the different classes of arthroplasty designs and a discussion of areas for further research (aimed at improving the in vivo performance of the prosthesis), are the subjects …of the present review. Show more

Keywords: Elbow joint, anatomy, kinesiology, biomechanics, arthroplasty

DOI: 10.3233/BME-1996-6505

Citation: Bio-Medical Materials and Engineering, vol. 6, no. 5, pp. 353-365, 1996

Authors: Lewis, Gladius | Clark, M.C. | Harber, Mark S. | Vaughan, Michael

Article Type: Research Article

Abstract: The stresses in various sections of two-dimensional models of the elbow joint, without and with a prosthesis (the humeral component of a total elbow prosthesis), were obtained using the finite element analysis method. Three parameters were varied: type of applied load; method of fixation of the prosthesis to the contiguous bone; and shape of the head of the prosthesis. The results are discussed with particular reference to stress shielding and overload in the cortical and cancellous bones, respectively, and a qualitative comparison between the present values and those given by previous workers who used three-dimensional models. Comments are made regarding …the clinical implications of the results. Show more

Keywords: Total elbow arthroplasty, humeral component, finite element stress analysis

DOI: 10.3233/BME-1996-6506

Citation: Bio-Medical Materials and Engineering, vol. 6, no. 5, pp. 367-377, 1996

Authors: Torrisi, L.

Article Type: Research Article

Abstract: Nitrogen implantation and thermal nitridation processes are investigated to improve the wear resistance of titanium medical devices. Ion implantation uses 80 keV nitrogen ions and doses ranging between 1 × 1017 and 5 × 1017 /cm2 to modify the surface layers up to 140 nm depth. Stable surface layers are obtained at high ion doses by post-annealing at 550°C for 30 min. Thermal processes are developed as a function of the time (20–90 min) and annealing temperature (950–1100°C) in a dry nitrogen atmosphere. The amount of titanium nitride formed dwing the thermal process increases with the annealing temperature and …time. Samples are analysed by Rutherford Backscattering Spectroscopy (RBS), Auger Electron Spectroscopy (AES) and Scanning Electron Microscopy (SEM). Ion implantation and thermal nitridation processes increase the surface hardness and wear resistance improving the mechanical properties of titanium used for movable devices for total joint replacements, such as the hip and knee protheses. Show more

DOI: 10.3233/BME-1996-6507

Citation: Bio-Medical Materials and Engineering, vol. 6, no. 5, pp. 379-388, 1996