AAWSAP DIRD, Biomaterials, January 2010

Text

This text came with the file. It may have mistakes. When the text and the image disagree, the image is right.

UNCLASSIFIED/ /FOR OFFICIJ!tt tJ!H! er•tv
Another recent discovery is that treating the titanium surface with a silane compound
will create a surface chemistry that attracts certain biomaterials known as
proteoglycans. From this point, it is possible to lay down layers of collagen on the
surface from which connective tissues will form.
Titanium metal used for implants is usually a biomedical alloy, Ti-6Al-4V, since
biomedical alloys provide good corrosion resistance and reasonable fatigue life and are
much stiffer than cortical bone. The Ti-6Al-4V alloy is more suitable than is the Co-Cr
alloy for coating with HA because it has less potential proximal stress shielding and
bone resorption.
BIOMATERIALS IN DIALYSIS
Medical therapeutic dialysis, often called hemodialysis, is a method of removing uric
acid and other waste products from blood, a necessity when the kidneys fail. It is also
useful in removing exogenous poisons like ethanol, aspirin, barbiturates, and boric acid
from the blood in cases of poisoning.
Hemodialysis accesses the blood stream through the use of two large needles-one in
an artery and one in a vein-in order to flow a patient's blood through a series of hair­
th in, hollow-membrane, tube-like fibers.
A dialyzer is composed of thousands of tube-like hollow fiber strands encased in a clear
plastic cylinder several inches in diameter. Blood flows on the inside of the membrane
fiber, and a dialysate (extraction stream) flows across the outside. Low-molecular­
weight waste products pass out through the membrane, while blood cells and other
large molecules in the blood are retained. Figure 30 shows an illustration (left) and
photograph (right) of dialyzers used to treat kidney failure.
Blood lnlel
Ileader
Tube sheet
jpiiiilj!!!!!!II• Solution
outlet
Blood outle
Figure 28. Illustration (Left) and Photograph (Right) of a Blood Dialyzer as Used in Medicine
UNCLASSIFIED//FOA QFFI&I:wk 1481!! er•tY
24