Biomedical Engineering Reference
In-Depth Information
11
Bioactive polymer coatings to improve
bone repair
G. Helary and V. MiGonney, institut Galilée, France
Abstract
: The aim of this chapter is to describe the concept of bioactivity
arising from the observed biological performance of new biomaterials
when placed in contact with bone cell tissues. The bioactivity of materials
could be summarized as the control of the host response preventing foreign
body reaction. it represents one way of improving bone cell interactions.
The fixation and osteointegration of biomaterials for bone repair requires
specific and strong interactions of bone cell and materials - the stronger the
interactions the longer the implant will be integrated and be performing.
new biomaterials coatings were recently developed to obtain improved
bone repair. They are derived from bioactive polymers which were shown to
exhibit a controlled cell response and can be grafted onto different implant
material surfaces.
Key words
: bioactive polymers, biocompatibility, bone integration, host
response, osteoblast response, polymer coating, polymer grafting.
11.1 Introduction: concept of biocompatibility of
biomaterials for bone repair
Current developments in biomaterials especially designed for bone cell
interaction demand implants that exhibit bioactive surfaces capable of
preventing atypical fibrosis as a result of the foreign body response (FBR)
and favour osteointegration. Why are these new materials needed? What
are the specific requirements for these materials, particularly when they are
designated for joint replacement as hip or knee prostheses?
The origin of the failures of biomaterial implants may be found in lack of
control of the 'host response' leading to a foreign body response characterized
by fibrosis and encapsulation. Indeed, when biomaterials are implanted or
placed in contact with bone cell tissue, the 'cascade' of the host response
events which has been extremely well described by Ratner and by Anderson
1, 2
will occur. These series of events are activated at the wound site as soon
as wounded tissue is generated and take place whatever the nature of the
tissue and its location. nevertheless, the intensity and duration of each step
is greatly dependent on the extent of the wound, the nature of the wound
surrounding tissue and the vascularization of the implantation site tissues.
To summarize, the cascade of 'host response' events is characterized by
the following steps: protein adsorption, acute and chronic host inflammatory
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