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A new artificial bone strong enough to
support new bone growth but porous enough to be absorbed and replaced
by the human body has been developed. The developed material, dubbed
"Plasti-Bone," is made from a biologically compatible
plastic with a ceramic coating. When an arm bone or leg bone is
severely crushed, physicians usually cannot set it, making bone
grafts or amputation the primary options. The same is true for bones
damaged by diseases such as cancer.
ACR has shown that a CAT scan or MRI image can be made of the good
arm bone and converted to a "growth code" – a 3-D
virtual image – of the replacement bone segment. Using that
data, ACR's rapid prototyping technology then creates a micro-porous
calcium phosphate coated polymer 'bone' which is surgically implanted
where the damaged bone has been removed. The calcium phosphate coating
is very thin and allows the bone cells to attach themselves to the
implant. Growth factors could be added to the calcium phosphate
to encourage the bone growth at faster rates. What is left of the
real bone attaches itself to the polymer bone after about 8 weeks.
The real bone begins to 'grow through' the porous scaffold, 'eating'
the scaffold and the body naturally excretes the calcium phosphate
material. In 18 months, the bone is expected to grow back completely,
leaving the patient with a natural bone.
Proof that the process works has been shown in animal testing as
well as in tissue cultures. The material - which could reach the
market within 5 years - holds promise over metallic inserts, which
can't be absorbed by the body and must eventually be replaced and
biological materials that are too brittle to support much force.
The artificial bone can be custom-made to match the exact shape
of a patient's bone through computer design and "rapid prototyping"
fabrication. The control on the rate of absorption and the porosity
can be achieved controlling the thickness of the ceramic coating.
The porous nature of the Plasti-Bone material allows blood flow
through the healing area, while the material is tough enough to
resist the corrosiveness of human blood. Remanants of the natural
bone begins bonding to the Plasti-Bone in about eight weeks. Eventually,
the implant is "bioresorbed" - completely replaced by
new bone tissue.
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