Biomedical Engineering Reference
In-Depth Information
enables its applications to form-fit in close contact with the bone.
Ostim
®
can be used in metaphyseal fractures and cysts, alveolar
ridge augmentation, acetabulum reconstruction, and periprosthetic
fractures during hip prosthesis exchange operations, osteotomies,
filling cages in spinal column surgery, etc. [524, 526-536]. It
might
be incorporated into bones and a new bone formation is visible after
only three months [537]. For a number of clinical applications, Ostim
®
might be combined with other types of calcium orthophosphate
bioceramics, e.g
®
.
,
with a HA bioceramic core (Cerabone
) [525,
®
) [539].
Application of such combinations of a nanocrystalline Ostim
538] or with biphasic (β-TCP + HA) granules (BoneSaves
®
with
the microcrystalline calcium orthophosphate bioceramics appeared
to be an effective method for treatment of both tibia head compression
fractures [525] and metaphyseal osseous volume defects in the
metaphyseal spongiosa [538]. Besides, such combinations might be
used for acetabular bone impaction grafting procedures [539].
developed nano-sized HA/collagen biocomposites, which
mimicked the nanostructure of bones [178, 540]. After implantation,
such biocomposites can be incorporated into bone metabolism. Due
to processing difficulties and poor mechanical properties of bulk
calcium orthophosphates, their applications are currently confined to
non-load-bearing implants and porous bodies/scaffolds. Porous 3D
biocomposites of nanodimensional HA and collagen/polymer mimic
bones in composition and microstructure and can be employed as a
matrix for the tissue engineering of bone [75].
Owing to their low mechanical properties, the use of calcium
orthophosphates in load-bearing applications is rather limited:
calcium orthophosphates are too stiff and brittle for such use. Today's
solutions for weight-bearing applications rely mostly on biologically
friendly metals, like cobalt-chromium alloys, titanium and its alloys,
as well as stainless steel 316L, but problems with stress-shielding
and long-term service can cause failures. All these metals, although
nontoxic, are always bioinert and cannot bond to bone directly. In
order to improve the biological properties of the metallic implants,
nanostructured calcium orthophosphates (mainly, apatites) are
generally used as a coating material to accelerate bone growth
and enhance bone fixation [160, 161, 281, 377, 481, 541-562].
The coating techniques include thermal spraying, sputter coating,
pulsed laser deposition, dynamic mixing method, dip coating, sol-
gel method, electrophoretic deposition, biomimetic process, hot
isostatic pressing, and some other methods [563]. In the majority
Cui et al.
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