Journal of biomedical materials research最新文献

Using a semiquantitative animal model of standardized injuries to parenchymatous organs resulting in a range of degrees of hemorrhage, we compared freeze-dried amylose succinate topical hemostat to the most widely used commercially available products. Hemostatic efficacy parameters included bleeding time, blood loss, incidence of rebleeding, and amount of material used. Although no material was consistently superior in all parameters, in general amylose succinate and microcrystalline collagen performed equally well and both were significantly more effective than oxidized regenerated cellulose. Both amylose succinate and oxidized regenerated cellulose were superior to microcrystalline collagen, however, in biodegradation time, inflammatory response and adhesion-forming potential. Details of the animal model and an adhesion grading scheme are presented.

Rapid growth in the field of applied biomaterials poses new ethical problems in the design, manufacture, evaluation, and regulation of medical devices and implants. This article addresses some of these ethical concerns and points out the ethical responsibilities of the scientists and engineers working in the field of biomaterials. The need for the development of a code of ethics by the Society for Biomaterials is also discussed.

This article deals with the use of carbon-fiber-reinforced-carbon materials for the manufacture of hip prosthesis stems. It considers the manufacturing process of carbon-carbon (C-C) composites made of carbon fibers infiltrated either with dense pyrolytic carbon or silicon carbide (SiC) through chemical vapor infiltration. The chemicophysical properties of these composites are examined according to their structures. The long-term response (2 years) of cortical bone to various types of carbon-carbon was evaluated mainly for bone contact and ingrowth. Carbon-carbon coated with calcium phosphate was found to speed up the bone formation as compared to pyrolytic carbon or SiC coatings. The low modulus of elasticity of the C-C materials could be responsible for quicker bone contact as compared to a much stiffer material like sintered aluminum oxide. The biomechanical performance of C-C hip stems was assessed through (a) implantations into cadaver femurs, (b) fatigue testing, and (c) finite element analysis. These tests showed: (a) a better stress transfer as compared to a metal prosthesis having the same design, (b) no fatigue damage, (c) a computerized stem stress distribution in accordance with the fractures obtained during static mechanical testing.

This investigation was directed toward the tissue reaction and wound healing response of an ePTFE prosthesis implanted in a human subject as an arteriovenous fistulae for over 7 years. Due to the frequent puncture of the prosthesis for hemodialysis access, the pattern of healing is markedly different from that normally observed in ePTFE grafts in humans. The ePTFE graft material of the AV fistula was completely incorporated in fibrous tissue with prominent pseudointima formation (inner capsule), fibrous tissue within the graft and a well-adhered periadventitial layer (outer capsule). In the portion of the graft most frequently punctured, the wall of the graft was composed mainly of fibrous tissue containing dissociated fragments of ePTFE. Biochemical analysis of the fibrous tissue across the wall of the graft revealed that it contained types I, III, and V collagen, with type I greater than III greater than V. The type V collagen was present in largest percentage at the luminal surface and in decreasing percentage in the ePTFE material and outer capsule. This analysis suggests that collagen type deposition in this prosthesis occurs in a manner similar to a normal healing wound, except for the unusual pattern of type V collagen deposition, which may be an adaptive variation of the healing response.

Developers of biosensors as medical devices are using emerging technologies that incorporate chemical assays with fiber optics and semiconductors. These biosensors will eventually become indwelling catheters for monitoring blood analyte concentrations as well as functioning as controlled feedback elements for artificial organs. Materials used in these devices are subject to problems of manufacture and reliability as well as those induced by the human body's response to these "foreign agents." The Division of Mechanics and Materials Science in the Center for Devices and Radiological Health at the Food and Drug Administration has initiated a program to investigate factors that effect sensitivity, selectivity and reliability of sensors used in biological applications. Our group's principle focus is on sensors of chemical processes. This article is an outgrowth of our research efforts and is a review of some of the technologies that are currently available or becoming available for these applications. The goal of our research is to identify factors that will have an impact on the reliability of long-term implanted medical devices with particular attention to sensors used in feedback-controlled therapeutic systems.

A large increase in medical products liability litigation during the past 40 years has resulted in a flood of litigation against drug and device manufacturers. The medical technology and chemical industries are prime targets for products liability litigation. Physicians and other health care providers are willing to accept a reasonable degree of risk associated with the use of a medical product when compared to the benefit to be achieved by that product but lay juries are less likely to tolerate the concept of an acceptable failure rate. Plaintiffs' lawyers believe that the medical products industry should be held to a standard of absolute liability and that anyone injured by a medical product is entitled to recover without regard for the circumstances. Large compensatory and punitive damage awards, the high cost of insurance, large defense costs, and low profit margins have forced some companies to remove their products from the market. The medical or biomaterials manufacturer can significantly reduce its exposure for products liability by adopting a successful product safety program. Manufacturers have significant control over the quality, safety, and reliability of their products through appropriate design, testing, manufacture, labeling, and sale of quality products.