Biomedical Engineering Reference
In-Depth Information
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5
log
10
CFU ml
-1
11.1
Comparison of
in vivo
MRSA strain 88244 adhesion on
bioactive polymer-coated (h) or control silicone prostheses (j). A
double-blind partial knee replacement was performed in 11 rabbits
with 6 Q5-coated prostheses and 5 silicone prostheses fitting
into the intramedullary canal of the tibia. MRSA 88244 (10
7
CFU)
were injected into the knees. The number of bacteria adherent on
prostheses was determined 24 h later. Results are means ± SD of
6 Q5-coated and 5 control silicone prostheses (
p
<0.0035). MRSA :
methycillin resistant
Staphylococcus aureus
fact, despite this displayed property, TA6V cannot be really classified as a
'biocompatible' material for orthopaedic applications since the bone/ Ta6V
implant interface is not functional, showing weak integration into bone tissue
and then limited long-term survival. Moreover, the diffusion of cytotoxic
metallic ions in the surrounding tissues may provoke chronic inflammation
and then be the cause of severe damage. Various surface modifications
have been proposed in order to improve the bone conductivity and the
bone/surface cohesion of titanium (Ti) and TA6V alloy surfaces: micro and
nanostructuration, coating with HaP or other ceramics
24
and development
of bioactive surfaces (proteins coating, RGD peptides coating, chemical and
thermal treatment,
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bioactive polymers grafting). In each case, the aim
is to enhance osteointegration and thereby the anchorage of the implant in
the surrounding osseous tissue, providing a stable and active biointerface
strong enough to support functional loading.
Despite the success of Ti alloys in orthopaedic applications, the rate of
osteointegration is nevertheless relatively slow, leading to weak anchorage and
a poor quality of osseous surrounding tissues (fibrosis). The idea of coating
Ta6V with bioactive ceramics like HaP and calcium silicate ceramics which
are able to enhance osteoblast cell differentiation was smart and showed
an interesting improvement of the bone tissue/implant interface as well as
bone mineralization and growth. nevertheless, the good results obtained
with HaP-coated surfaces were counterbalanced by several failures mainly
caused by the lack of control of the ceramic coating process, leading to
