Medical textile products process

Since several years the Institute of Textile Technology in Aachen (ITA) develops, in close interdisciplinary cooperation with engineers, chests, biologists and medical partners, production processes, products and testing methods in die field of medical textiles and biomaterials. 

From a scientific point of view, medical textiles are located at the interfaces between technical disciplines and life sciences. On the one hand, the technical aspect concerns textile engineering, material chemistry, process control, testing and certification, etc., which are needed for the manufacture of high-quality medical textile products. On the other hand, life sciences such as medicine, microbiology, and other related subjects are required for the development of functional performances of these products. In practice, the different scientific and technical disciplines interact and overlap with one another, with new developments in any one of these branches able to generate new innovations in others. For example, new superabsorbent and gel-forming substances invented in chemistry have been applied in the development of new baby diapers and adult incontinence products. 

Textile materials used for medical applications include fibers, yams, fabrics, and many types of composites, which are processed in many ways to form the medical textile products. As shown in Figure 2.1, the basic constituent for medical textile products is polymers, which are made into fibers through a fiber-making process. These polymers differ from those used in conventional textiles, in that they should possess nontoxicity, nonallergenic response, the ability to be sterilized, good mechanical properties, strength, elasticity, durability, and biocompatibility. Sterility is an essential requirement for medical textile products, and therefore the polymers must be able to withstand the harsh physical and chemical conditions that are generally found in a sterilization process. 

As the basic component of medical textile materials, the structures and properties of the constituent polymers have a significant effect on the biodegradability, biocompatibility, absorbency, antimicrobial property, and other functional performances of the final medical textile products. Functional modifications of polymers have far-reaching effects on the fibers, yams, fabrics, and textile materials that are processed in a series of downstream operations. In order to generate the desired product performance characteristics for their diverse applications such as hygiene, protection, therapeutic, nonimplantable or implantable materials, extracorporeal devices, etc., the chemical and physical structures of the relevant polymers should be engineered to suit their required specifications. 

Biocompatibility testing is an essential requirement for regulatory approval of medical devices such as medical textile products, and it is important to follow strict testing protocol in order to avoid potential pitfalls that could delay a product launch. During the product development process, it would be sensible to start the process early enough to allow for thorough and complete testing. As with any business or scientific endeavor, it is important to communicate all details accurately and be as up to date as possible on all test requirements. It is often necessary to consult qualified professionals to provide the expertise that is required for the successful completion of the various tests. 

Figure 16.2 shows the product development process from the beginning, when an idea is formed, to the point when customers can use the product. The product development cycle normally begins with an idea to serve a particular customer need, followed by a series of research, development, manufacturing, marketing, distribution, customer service, and other related commercial activities that comprise a full product value chain. Because of the various types of risks involved, the success of medical textile product development depends on the careful execution of the many tasks that are needed to complete the development process. It has been reported that on average, for every 100 projects that go into development, 63 get killed before the final stage, 12 are... 

In addition to the core technologies, the development of medical textile products requires a number of other NPD capabilities which the medical textile companies may not possess. SAs offer an economical way to access these capabilities from external sources. In the search for NPD capabilities that can allow medical textile companies to develop products effectively and efficiently, strategic networking with a diverse range of partners can offer an ideal way of combining the companies internal capabilities in core technologies with external capabilities in the other important areas of the NPD process. 

Quality of the product and time to market are the two most important objectives of the product development process. This is because buyers and regulatory authorities both put their first priority on product quality, that is, inherent superiority over existing products. Second, the regulatory process is lengthy and technological advances have made the development of nonpatent-inMnging me-too products much easier. A reduced time to market is therefore important to extend the life span of the medical textile product under development. 

After a brief introduction to the human body, the book gives an overview of medical textile products and the processes used to manufacture them. Subsequent chapters cover superabsorbent textiles, functional wound dressings, bandages, sutures, implants, and other important medical textile technologies in detail. Biocompatibility testing and regulatory control are then addressed, and the book finishes with a review of research and development strategy for medical textile products. 

To define what we mean by a medical textile, it may be appropriate to use the same approach that has been established for a product qualifying as a medical device. Using this approach, n medical textile is defined as any textile product manufactured with the intention to be used to diagnose, prevent, monitor, treat or alleviate disease, to compensate an injury or handicap, to investigate, replace or modify the anatomy or a physiological process, or to control conception. This definition taken from the European Medical Device Directive (its U.S. counterpart is issued by the Food and Drug Association [FDA]) is made from a regulatory perspective and specifies what criteria medical devices need to fulfil to make them safe to use and make it possible to sort out... 

In spite of progress achieved, serious challenges remain to acquire a clear and full understanding of potential fiber implications in the field of implantable medical textiles. The product stmcture—property relationship is an important research field. We must be able to mimic native mechanical and stmctural parameters to best suit our devices. We can thus adapt the mechanical parameters to specific applications. Regarding tissue engineering, it remains to develop efficient manufacturing processes for the preparation of fibrous scaffolding. 

Polyurethanes (PUs) are a family of condensation polymers that include the urethane (-NHCOO-) group in the chemical structure (Figure 5.1). The history of PUs started in 1937 when Dr Otto Bayer of Bayer Germany invented the diisocyanate polyaddition process. The early applications of PUs were mainly on soft foams and nonsegmented semicrystalline fibers. The lack of rubber materials during WWII has led to the intensive development of PU elastomers. In 1950, Bayer launched the first PU elastomer product, Vulkollan rubbers. Since then, PU elastomers have been used extensively, particular in medical, textile, automobile, and architecture industries [1-3]. 

Medical textiles are classified in Scheme 6.1. This scheme detailing constituents of various polymeric substances (eg, natural or synthetic) and their construction processes as outlined in the previous section is important in defining medical textiles aptly. Similarly, testing the properties and performance of medical textiles with suitable methods under accredited standards is essential. Thus, it is worthwhile to adequately describe all test methods, performance testing features, results analysis, and presentation guidelines of test results prior to marketing and commercialization of a device or product. This is done so that care and quality assurance of medical textiles will be documented appropriately, which benefits users. 

Sterilization is a term referring to any process that eliminates or kills all forms of microbial life, including transmissible agents such as fungi, bacteria, viruses, spore, etc., which are present on a surface or contained in a fluid or a compound such as a medical textile material. Sterilization can be achieved by applying heat, chemicals, irradiation, high pressure, or filtration. In the medical textile industry, the main methods used to sterilize products are heat, ethylene oxide, gamma irradiation, and electron radiation. 

To build up the capabilities that are needed for developing quality products, medical textile companies need to complement their own capabilities with external sources of capabilities when in-house development lacks economy of scale. More importantly, in a dynamic product market external sources of capabilities are essential, since a fixed set of internal capabilities may not be flexible enough to cope with the pace of market and technology changes. Strategic alliances (SAs) in various forms are therefore essential for the NPD process. 

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