Biomedical Engineering Reference
In-Depth Information
(a) (b)
9.4
Biodegradable composites with degradable polymeric matrix:
(a) Fibre reinforced composites composed of a PCL matrix integrated
to PLLA fibres; (b) PCL matrix loaded with HA micrometric particles.
more rapid diffusion of fluids at the matrix/fibre interface and also capable
of not limiting mechanical strength and fatigue properties offers an optimal
compromise condition for improving the final composite properties.
this aspect could be further compromised by the 3D architecture of
the substitute (i.e. porosity) and its interaction with the surrounding tissue
(Agrawal and Ray, 2001). It is worth noting that properly designed composite
materials with high controlled degradation are able to provide new bone
growth thanks to the right balance between vascularization promotion and
mechanical support. The, final biological behaviour is first determined by the
presence of a multi-scale porosity with tailored characteristics, in terms of
pore interconnections and pore size, as the degradation mechanisms proceed.
a well-organized pore network within the scaffold may potentially control
cell colonization and fluid transport through its peculiar geometry (Van
Eden and Ripamonti, 1994). The increased amount of open space combined
with the progressive formation of channels within the biodegradable matrix
caused by polymeric fibre degradation allows all cited mechanisms to be
supported thanks to more rapid degradation mechanisms. However, some
studies demonstrated that an excessive presence of open spaces may have
led to premature fibrous tissue formation before new bone had a chance to
infiltrate the scaffold. Furthermore, a large pore volume fraction negatively
affects the mechanical performance of the composite, drastically reducing
its ability to support static and cyclic loads.
9.5.2 Inorganic filler reinforced composites
with a degradable matrix
in recent years, many favourable reports have been published on the use of
bioactive materials such as hydroxyapatite (HA) as a substitute for defective
bones or teeth in dental, maxillofacial and orthopaedic surgery. From a
