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Several years ago the Orthopedic and Rehabilitation Devices Panel of the
United States Food and Drug Administration (FDA)
approved InFUSE Bone Graft for use with the LT-CAGE™ Lumbar
Tapered Fusion Device for use in spinal fusion
procedures.
According to Medtronic, "the Infuse Bone Graft,
when used with the LT-CAGE Lumbar Tapered Fusion Device, will
be indicated to treat certain types of spinal degenerative
disc disease, a common cause of low back pain."
"More
than 150,000 Americans have lumbar spinal fusion surgery each
year, which currently requires two surgeries - one to harvest
small pieces of bone from the iliac crest of the patient's hip
(autograft) and the second to implant it in the spine.
Numerous studies have shown that patients experience
considerable more pain from the harvesting than they do from
the fusion procedure itself, and the hip pain can last for
years after surgery."
According
to the Medtronic press release, dated January 10, 2002,
"InFUSE Bone Graft replaces the use of autograft bone because
it contains a recombinant human bone morphogenetic protein or
rhBMP-2, which induces the body to grow its own bone where
needed.
*
The above information
was quoted from the January 10, 2002 press release by
Medtronic. More information is available
on the
Medtronic website. |
The doctors of Central
Texas Spine Institute have found that well-informed patients
make the best decisions regarding treatment of their back
injuries.
We try to keep our patients informed of current
technology as well as new technologies that might become
available in the not too distant future.
Spinal fusion is one of
the surgical procedures that have been performed for many
years to treat chronic painful spinal conditions, in both the
neck and the lower back.
Additionally, spinal fusions have been performed to
correct spinal deformities such as scoliosis, or curvature of
the spine, and instability or abnormal movement between
adjoining vertebras.
Spinal fusion is the linking of adjacent vertebra through the
process of bone formation.
Usually, this procedure is augmented with the addition of
metal implants such as rods and screws or hooks and rods.
Newer intervertebral implants that are cylindrical
shapes can actually be placed into the area where the
intervertebral disc joins one vertebra to the other.
The hallmark of spinal fusion requires that bone grow
between one vertebra and the other.
Until very recently, this has been accomplished with
the use of bone graft material.
The gold standard, which all other graft materials are
compared to, is the patient's, own bone.
To use the patient's own bone, requires taking bone
from one site in the patient's body, usually the pelvic bone
or the iliac bone.
This bone is "harvested" using chisels, gouges and other
bone-cutting instruments.
That bone is then packed between the vertebras or
around the vertebra in such a way to stimulate bone growth and
ultimately fuse the vertebra together.
Even in the best of
circumstances, fusions do not occur 100% of the time.
Many conditions have to be perfect for the bone to grow and
bridge the gap between vertebras.
We know that when the vertebra move during the time
that bone is trying to heal diminishes the chance for a
successful fusion.
This is one reason that metal implants have been used
to supplement the fusion. In addition, we know that fusions are much more difficult to
achieve in patients who have certain types of systemic
illnesses or osteoporosis, or in those patients who are heavy
smokers. Nicotine
contained in cigarette smoke decreases the oxygen carried to
the bone reducing the likelihood of a successful fusion.
Taking the bone from the
pelvic bone requires a second or separate incision and is
usually considered one of the more painful aspects of spinal
fusion surgery.
Harvesting the bone adds expense to the surgical
procedure, increases the surgical time, increases the risk of
chronic pain and injury to the nerves in the area where the
incision is made, and is overall one of the least desirable
aspects of doing spinal fusions booth for the surgeon and the
patient.
July 2, 2002, The Food
and Drug Administration (FDA) officially approved InFuse
Bone Graft/LT Cage
Tapered Fusion Device for treatment of degenerative disc
disease.
InFuse
is a new technology using Recombinant Human Bone Morphogenetic
Protein-2 (rhBMP-2).
In 1960, an orthopedic surgeon by the name of Marshall Urist
discovered, isolated and extracted, rhBMP-2, a protein that is
normally found in human bone.
Dr. Urist discovered that this particular protein was
the chemical responsible for the induction of bone growth.
It is locally active in conditions where there has been
a fracture or any type of injury to the bone.
Scientists subsequently found that BMP, or bone
morphogenetic protein actually consists of a number of related
proteins.
Similar to the process
that is used to make other proteins such as insulin,
scientists have isolated, characterized, and cloned several
different types of BMP.
RhBMP-2 is just one of the proteins which they have
identified and it has a distinct amino acid sequence.
RhBMP-2 works by causing
primitive undifferentiated stem cells to become cartilage and
bone-forming cells. Based upon experimental work that has been done so far, it
does this by causing undifferentiated stem cells to
differentiate and evolve into mature bone-forming cells.
Several hundred experimental studies have been
published that have shown that rhBMP-2 is equal to and in most
cases superior to utilizing the patient's own bone.
Pre-clinical studies have shown that the new induced
bone formation is faster and results in a higher fusion rate
than utilizing the patient's own bone, harvested form the
iliac crest.
Histology or microscopic studies have proven that the
formation of normal bone takes place without any evidence of
inflammation, a process called "osteoinduction".
RhBMP-2 appears to be extremely osteoinductive, and
depending upon its proper use with a good carrier, drives the
process of natural bone formation.
When rhBMP-2 is utilized
with titanium intervertebral implants, we are able to obtain
immediate fixation or stabilization of the painful vertebral
segment, and we are able to obtain the induction of new bone
formation resulting in spinal fusion.
This procedure can now be done without the need to
harvest bone graft from the patient's pelvic bone.
Using RhBMP-2 rather than the patient's own bone will
eliminate a great deal of the patient's postoperative pain and
reduce the need for postoperative pain medication.
Now that the FDA has
approved rhBMP-2, the doctors of Central Texas Spine Institute
will begin using it for spinal fusions, where appropriate.
Other potential risks associated with spinal surgery are not
removed by the use of this material, and we strongly encourage
our patients to become informed and ask questions of their
surgeon. Prior to
undergoing any surgical procedure, the patients should be
aware of the risks, benefits and any potential complications
of the surgery. |
