Alloy surrounding tissue

Nickel-containing alloys are used in patients in joint prostheses, sutures, clips, and screws for fractured bones. Corrosion of these implants may lead to elevated nickel levels in the surrounding tissue and to the release of nickel into extracellular fluid (lARC 1990 Sunderman 1989a Sunderman et al. 1986, 1989c). Serum albumin solutions used for intravenous infusion fluids have been reported to contain as... 

Bioinert materials are materials that display minimal, if any, interaction with surrounding tissues examples of these are titanium and its alloys, alumina, partially stabilised zirconia, carbon and possibly ultrahigh molecular weight polyethylene (UHMWPE). In the case of bioinert materials bone remodelling occurs by a shape-mediated contact osteogenesis. 

Titanium and its alloys are known as being the most suitable metalUc biomaterials. They are used in orthopaedic applications due to their excellent mechanical properties. More importantly, they form a very stable oxide layer in body fluid and hence possess exceptional biocompatibility as compared with other metal implant materials. However, these materials undergo failure due to siuface reactions and mechanical loading. Passive corrosion or accelerating processes snch as wear have led to the release of titanium and the other alloying elements into the surrounding tissues. This section discusses the corrosion issues in titanium and its alloys, cobalt-based alloys, stainless steels and nickel-titanium alloys. 

In vitro experiments designed to study the ultrastructural details of bone-implant interfaces made from cpTi and Ti alloy may provide additional clues as to the histologic and ultrastructural differences which have been observed with these materials. Since cHnical implants made from both materials appear to be successful [Branemark, 1983 De Porter et al., 1986], it is possible that because of the difference in mechanical properties between unalloyed and Ti alloy material, the longer-term tissue interface results from differences in bone remodeling due to the local biomechanical environment surrounding these materials [Brunski, 1992]. This hypothesis requires continued investigation for more definitive... 

During the last 30 years, advances in material science have led to the development of synthetic materials that have unique properties for medical applications. Metals, ceramics, polymers, composites are the main classes of synthetic biomaterials. Metals and their alloys have been used in various forms as implants and for hard tissue repair (e.g., dental implants, joint replacement, fracture plates, screws, pins). They are mechanically strong, tough and ductile. They can be readily fabricated and sterilised. However, they may corrode in the biological media, their densities are high and their mechanical properties mismatch with bone, which may result undesirable destruction of the surrounding hard tissues. 

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