Non-biodegradable implants

Non-biodegradable implants, such as silicones, ceramics, titanium, steel, carbons, polyesters and the like, are meant to stay in the body for fife. Their role is often to support or enhance endurance under high static or cyclic load-ing/unloading or other repetitive expansive/contractive motions. However, some implants need to be removed after they have rectified a malfunction or disorder in bodily functions. Historically, there exists a lot of evidence supporting the use of implantable materials in the body however, their systematic use really took off from the late 1800s, when aseptic without microorganisms techniques were adopted as standard practice (Encyclopaedia, 2007). In the late nineteenth to early twentieth centuries, the use of metals... 

Table 5.1 Examples of biodegradable and non-biodegradable implantable materials...

The release of tobramycin sulphate from non-biodegradable, spherical PMMA implants is biphasic and can be described by biexponential linear regression analysis. 

Which of the following is/are an example(s) of non-biodegradable matrix-type implant (a) Norplant (b) Compudose (c) Implanon and/or (d) Zoladex. 

Since EVAc is a non-biodegradable polymer, the implanted device has to be surgically removed from the host after completion of the immunization process. Hence, it would be advantageous to use biodegradable devices for the controlled release of antigen. 

At present these materials are too expensive to be considered as viable alternatives to the commodity plastics in packaging but they do have potential applications in biomedical products such as orthopaedic implants and even as temporary replacements for parts of the pericardium during open-heart surgery. In this kind of application, performance is much more important than cost. However, Biopol may be able to replace non-biodegradable polymers in paper coating which would then allow paper composite materials to biodegrade much more rapidly in compost and similar environments. 

Table 10.1 represents the polymers which are used in medical devices. They include both synthetic non-biodegradable and biodegradable polymers. They are mainly used to produce various medical devices such as implants, drug carriers, protective packaging materials, and healthcare items [12]. 

Agrawal, C.M., Best, D., Heckraann, J.D., Boyan, B.D. (1995) Protein release kinetics of a biodegradable implant for fracture non-unions. Biomaterials, 16, 1255-1260. 

Non-biodegradable two phase corneal implant and metliod for preparing same 5,067,961 1991 Kelman and DeVore... 

However, the development of in vivo applications for PNIPAM is limited by its non-biodegradability and the presence of amide moieties that reduce its biocompatibility. For this reason, other thermo-responsive polymers have been investigated in recent years. Poly(N-vinylcaprolactam) is a promising alternative. This polymer has a LCST between 35 and 38°C, again close to the temperature of the human body, and is characterized by high biocompatibility and low toxicity (Konak et al, 2007 Medeiros et al, 2010 Shtanko et al, 2003 Yanul et al, 2001). Additionally, amphiphilic copolymers such as Pluronics and Tetronics have been developed, based on copolymers of polyethylene oxide and polypropylene oxide. These copolymer systems exhibit a solution-gel transition at close to human body temperature that permits their application as injectable implants (Samchenko et ai,2011). 

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