Biomedical Engineering Reference
In-Depth Information
reach this goal include elaboration of hybrid materials,
5
coating surfaces with
specific proteins, peptides
6-11
or bioactive synthetic macromolecules.
12-14
The
first approaches appear to be the smartest ones as well as the best candidates
for overcoming the FBR since they involve natural molecules that are less
likely to initiate an uncontrolled immunogenic and/or inflammatory response.
nevertheless, taking reported results in the literature into account, the balance
between advantages and disadvantages is not in favour of them:
∑ The coating of biomaterial surfaces with proteins presents some enzymatic
instability and may lead to emergence of immunogenicity and to the
appearance of susceptibility to infection.
∑ The grafting or coating of surfaces with peptides is more selective and
thus a better candidate for improving the cell/surface interaction but
cyclic peptides should preferably be used rather than linear ones because
of their lack of specificity.10,
10, 15
nevertheless, the cost, instability and
enzymatic degradation of the coating may tip the balance away from the
advantages of peptide coating of surfaces which favour differentiation
of osteoblast cells.
Grafting bioactive synthetic polymers favouring bone cell adhesion,
proliferation and differentiation onto surfaces has been developed to enhance
osteoblast differentiation, to improve the quality of the bone cell/surface
interface and to avoid the problems of enzymatic instability and the cost of
the final medical device. In addition, the use of bioactive polymers that have
been shown to present the capacity to prevent bacteria adhesion in bone cell
repair application appears to be really promising.
The appropriate material for bone cell tissue regeneration could be obtained
by grafting biomolecules and/or bioactive polymers on to the surface in order
to maintain differentiation of osteoblast cells and to control the host response
avoiding its transformation into FBR. Bringing bone cell into contact with
biomaterials will give most information about events at the interface.
11.3 Need for bone integration and repair
biomaterials
Primary total hip and knee arthroplasties, and revision of the same, have
been the major subject of numerous studies and then of the development
of bone integration and bone repair materials. During the last 20 years, the
occurrence of first intention prostheses has steadily increased, around 10% per
year, and it has no reason to stop increasing mainly because of the ageing of
the population. on the other hand, revision of total hip or knee prosthesis is
also increasing because of the failures of the implants.
16, 17
The problems of
patients and the diseases that occur at the origin of primary intention total hip
prostheses (THP) are numerous, different and well identified, while revision
and/or second intention THP are due to two main causes:
