Biomedical Engineering Reference
In-Depth Information
of calcium orthophosphate cements but also some difficulties of
filling vertebral bodies. In order to maintain a good cohesion and
reduce filter pressing, calcium orthophosphate cements need to
be more viscous (hence, less injectable) [197, 198]. For example,
calcium orthophosphate cements might be modified by addition of
polysaccharides [97, 108, 335-338] and/or gelatin [278, 339-344].
Another type of concerns has been raised that the use of self-
setting calcium orthophosphate formulations for the augmentation
of fractured and osteoporotic bones might aggravate cardiovascular
deterioration in the event of pulmonary cement embolism by
stimulatingcoagulation[577].Toinvestigatethesepotentialproblems,
2.0 ml of either calcium orthophosphate or polymethylmethacrylate
(PMMA) cement were injected intravenously in 14 sheep. Intravenous
injection of calcium orthophosphate cement resulted in a more severe
increase in pulmonary arterial pressure and decrease in arterial
blood pressure compared to the PMMA cement. Disintegration
of the calcium orthophosphate cement seemed to be the reason
for more severe reaction that represents a risk of cardiovascular
complications. The authors concluded that further research efforts
should aim at improving cohesion of calcium orthophosphate
cements in an aqueous environment for future clinical applications
such as vertebral body augmentation [577].
To conclude the biomedical part of this review, one should mention
that, although the long-term outcomes are still poorly documented,
currently there are no doubts concerning a very great potential of
the clinical applications of self-setting calcium orthophosphate
formulations for healing of bone and dental defects. For example, a
bioresorbable calcium orthophosphate cement was once found to be
a better choice, at least in terms of the prevention of subsidence, than
autogenous iliac bone graft for the treatment of subarticular defects
associated with unstable tibial plateau fractures [578]. Furthermore,
BoneSource
TM
was found to be safe and effective when used to fill
traumatic metaphyseal bone voids and appeared to be at least as
good as autograft for treatment of these defects [579]. However,
in other studies, autologous cancellous grafts were demonstrated
to lead to a significantly better bone regeneration compared to the
application of calcium orthophosphate granules produced from a
self-setting calcium orthophosphate cement powder after 6 weeks
[580]. As this text is intended to be read mainly by chemists and
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