Biomedical Engineering Reference
In-Depth Information
needed. The challenge is to place a biomaterial at the site of surgery
by the least possible invasive method. In this regard, IBS appear to be a
convenient alternative to solid bone-filling materials. They represent
ready-to-use suspensions of calcium orthophosphate microspheres
[888, 889], nano-sized rods [890] or powder(s) in a liquid carrier
phase. However, addition of other phases, such as calcium sulfate
[891], is possible. They look like opaque viscous pastes with the
rheological properties, sufficient to inject them into bone defects by
means of surgical syringes and needles. Besides, IBS could be easily
produced in a sterile stage. Their stable composition and mechanical
properties are suitable for reproducibility of the biological response
[892]. All types of IBS are divided into 2 major groups: self-setting
formulations and those, which does not set. The former ones belong
to cements and concretes (see section
above and Chapter 5 for
details), while the latter ones are described here.
IBS requires suitable rheological properties to ensure bonding
of the mineral phase
6.4.2
with good cell permeability. Usually,
the necessary level of viscosity is created by addition of water-
soluble polymers [131, 893, 894]. Therefore, the majority of calcium
orthophosphate-based IBS formulations might be considered as
a subgroup of calcium orthophosphate/polymer biocomposites.
For example, an IBS was described that involved a silanized
hydroxyethylcellulose carrier with BCP (HA + β-TCP) [895]. The
suspension is liquid at pH within 10-12, but gels quickly at pH <
9. Injectable composites can be formed with β-TCP to improve
mechanical integrity [548]. Similarly, Bennett et al
in situ
.
showed that
a
-glycolide-based biocomposite reinforced
with HA or β-TCP can be used as an injectable or moldable putty
[896]. During the cross-linking reaction following injection, carbon
dioxide is released allowing the formation of interconnected pores.
Furthermore, HA/poly(L-lactide-
polydioxanone-
co
-ε-caprolactone) biocomposite
microparticles were fabricated as an injectable scaffold via the
Pickering emulsion route in the absence of any molecular surfactants.
A stable injectable oil-in-water emulsion was obtained using water
dispersed HA nano-sized crystals as the particulate emulsifier and a
dichloromethane solution of poly(L-lactide-
co
co
-ε-caprolactone) as an
oil phase [897].
developed viscous IBS biocomposites based on BCP
(60% HA + 40% β-TCP) and 2% aqueous solution of HPMC that was
Daculsi et al
.
Search WWH ::
Custom Search