Body fluids, implant failure

Body fluids, contain a high concentration of Ions and can cause implant failure In the following two ways ... 

When a medical device is in contact with body fluid such as blood, the first thing that occurs on the surface is protein adsorption [96-98]. Proteins in solution trying to minimize the total surface energy is the thermodynamic driving force of protein adsorption on solid surfaces. In blood contact protein adsorption is believed to be the initial event in thrombus formation [99-101], calcification [102-104], and biofilm attachment [105-107], which leads to the failure of implanted devices. Therefore, protein-reducing surface modifications of polyurethane biomaterials have been applied to improve the service life of implants. Previous studies of protein adsorption have focused on adsorption of albumin, IgG, and Fg, which are the predominant three proteins in blood plasma. Surface protein adsorption can be quantitated by several methods such as quartz crystal microbalance (QCM) [108-112], surface plasmon resonance (SPR) [113-118], and iodonization radiolabeling [78,119-125]. 

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. 

The inflatable prosthesis consists of two fluid-filled cylinders that are surgically implanted within the two erection chambers of the penis. These cylinders are connected by tubing to a pump that is implanted within the scrotum. To achieve an erection, the pump transfers fluid to the cylinders, increasing the intrapenile pressure. Following ejaculation, the fluid returns to the pump from the cylinders. The adjustable size and rigidity make this prosthesis seem more natural. This type of implant may experience mechanical failure there is a 10 to 15 percent failure rate in the first five years. If a cylinder leaks, the fluid inside is saline, which is absorbed by the body... 

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