Biomedical Engineering Reference
In-Depth Information
cement biocomposites revealed that they exhibited microsphere
degradation after 12 weeks of subcutaneous implantation, which
was accompanied by compression strength decreasing [1168].
Interestingly, but the amount of calcium orthophosphates in
biocomposites was found to have a greater effect on the early stages
of osteoblast behavior (cell attachment and proliferation) rather
than the immediate and late stages (proliferation and differentiation)
[1169].
(the samples were immersed into 1% trypsin/
phosphate-buffered saline solution at 37 °C) and
Both
in vitro
(implantation
of samples into the posterolateral lumbar spine of rabbits)
biodegradation have been investigated for nano-sized HA/collagen/
PLA biocomposites [610]. The results demonstrated that weight loss
increased continuously
in vivo
with a reduction in mass of ~20%
after 4 weeks. During the experimental period
in vitro
, a relative rate
of reduction of the three components in this material was shown to
differ greatly: collagen decreased the fastest, from 40% by weight
to ~20% in the composite; HA content increased from 45 to ~60%;
while PLA changed little.
in vitro
, the collagen/HA ratio appeared to
be slightly higher near the transverse process than in the central
part of the intertransverse process [610]. Hasegawa et al. [1170]
performed
In vivo
study, spanning over a period of 5-7 years, on high
strength HA/PLLA biocomposite rods for the internal fixation of bone
fractures. In that work, both uncalcined CDHA and calcined HA were
used as reinforcing phases in PLLA matrix. Those composites were
implanted in the femur of 25 rabbits. It was found that the implanted
materials were resorbed after 6 years of implantation. The presence
of remodeled bone and trabecular bone bonding was the significant
outcome. These data clearly demonstrate a biodegradation
independence of various components of biocomposites.
in vivo
6.7
Some Challenges and Critical Issues
The scientific information summarized in this review represents
the recent developments of calcium orthophosphate-based
biocomposites and hybrid biomaterials from a variety of
approaches, starting from conventional ones to tissue engineering.
Such formulations combined with osteoconductive, osteoinductive
factors, and/or osteogenic cells have gained much interest as a
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