Biomedical Engineering Reference
In-Depth Information
Chapter 7
Biocompatibility of
Polyaryletheretherketone Polymers
Jeffrey M. Toth BSE, Ph.D.
7.1 Introduction
Biological performance
d
The interaction between
materials and living systems, which takes into
account:
Biomaterials are placed within a living host.
Biocompatibility considers the interactions that take
place between the biomaterial and the host environ-
ment. Just as mechanical properties (strength, hard-
ness, fatigue, etc.) may have an influence on the
clinical performance of an implanted biomaterial,
components of biocompatibility may also affect
clinical performance. In the application of biomate-
rials to medical devices, adverse host responses can
cause device failure and necessitate device removal.
So what is biocompatibility? Is it a property of
a material like strength, hardness, toughness? An
event? We can get into trouble if we consider
biocompatibility as a property of a material. That is,
if we say, “Nickel is a biocompatible material,” we
ignore the 10
e
20% of the patient population in
which nickel is an antigenic substance
[1]
. If we say
that gold is biocompatible
d
that may be true for
dental applications, but it ignores the fact that noble
metals such as gold in contact with blood can lead to
thrombosis, and therefore are not hemocompatible. A
better way to think about biocompatibility is as an
event or interaction, not as a property of a biomate-
rial. In this way, the host responses to biomaterials
can be viewed as being tissue and organ dependent,
host specific, and species specific.
Jonathon Black, professor emeritus of bioengi-
neering at Clemson University and one of the
founders of the field of biomaterials, has created the
following lexicon to take this into account
[2]
:
Biocompatible
d
Biological performance in a
specific application that is judged suitable for that site/
situation
[2]
.
1.
The host response, which is the local and
systemic (affecting the entire body) response,
other than the intended therapeutic response,
of the living system to the material and
2.
The materials response, which is the response
of the material to the living system
[2]
.
This set of definitions illustrates that a material by
itself is not biocompatible, and that biocompatibility
is best viewed as an event or interaction, not as
a property of a biomaterial. In this way, the host
responses to biomaterials can be viewed as being
tissue and organ dependent, host specific, and species
specific. Therefore, the use/application, size, shape,
and so on are all important in determining the host
response to the implanted biomaterial. Note that
inflammatory responses and other adverse reactions
may take place. However, the material may evoke
a minimal biological (host) response and still be
considered biocompatible. When we think about the
components of biocompatibility, it means that at
a minimum the biomaterial must be:
Nontoxic
Nonmutagenic
Noncarcinogenic, and
Nonimmunogenic.
For this reason, the biocompatibility of poly-
aryletheretherketone (PEEK) will be considered in
