Biomedical Engineering Reference
In-Depth Information
well-organised and mineralised structure of newly-formed bone. In spite of a cer-
tain number of fractures in the MBCP wedges during implantation, or proximal
screws fractured without compromising the stability or post-operative correction
angles, high bone ingrowth was reported. This study indicated that MBCP wedges
in combination with orientable locking screws and plates are a simple, safe, and
fast surgical technique for HTO.
4.6 CONCLUSION
The concept of biphasic calcium phosphate ceramics (BCP) is determined by an
optimum balance between the more stable HA phase and the more soluble TCP.
The material is soluble and gradually dissolves in the body, seeding new bone
formation as it releases calcium and phosphate ions into the biological medium.
As a means of promoting these events, and in order to develop calcium phosphate
ceramics and other related biomaterials for bone grafts, a better control of the
biomaterials resorption and bone substitution processes is needed.
The main attractive feature of BCP ceramic is its ability to form a direct bond
with the host bone, resulting in a strong interface. The formation of this dynamic
interface is the result of a sequence of events involving interaction with cells and
the formation of carbonate hydroxyapatite CHA (similar to bone mineral) by
means of the dissolution/precipitation processes. Associating micro and macro-
prosity with the BCP concept has resulted in high osteogenicity and osteoinduc-
tive properties. At the present time, MBCP is commercially available in blocks,
particulates and customised designs. Specifi c matrices have been developed for
combination with bone marrow or mesenchymal stem cells for tissue engineering
(hybrid bone). The need for a material for Minimally Invasive Surgery (MIS)
has led to the development of a concept for BCP granules combined with a
polymer or calcium phosphate cement to create an injectable/mouldable bone
substitute.
The challenge today will be to improve technologies for large bone defect
reconstruction or for bone reconstruction in osteo radionecrosis, combining
tissue engineering and scaffold. To support this challenge, studies will have to in-
crease the capacity of osteogenic and hematopietic cell growth into large samples
(colonization), and to promote angiogenesis for living bone.
The second evolution of BCP concept will be the association with resorb-
able osteosynthesis for “orthobiologic system,” to avoid second surgery, time
to remove the metal osteosynthesis after bone healing at the expense of the bio-
ceramics, or to maintain on time unresorbable bioinert materials as PEEK or
titanium.
The third is the development of Minimal Invasive Surgery that required spe-
cifi c injectible bone substitute with or without self hardening; the combination
with Hydrogels is the main research and development in the fi eld of bone substi-
tute and tissue engineering.
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