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Spinal Disc Replacement
A
lumbar disc replacement is emerging as a new treatment
option for some types of
low back pain. Spinal disc replacement surgery has
recently been
FDA approved in the United States, and a growing amount
of research is being performed throughout the world, mostly
in Europe, on this new procedure. Lumbar disc replacement
may soon be a standard treatment for some
types of low back pain.
If you are interested in disc replacement surgery as a
treatment for your spine condition, please
contact us to determine
what option is best for you, what your insurance will cover
and any additional surgery costs.
The Problem: Degenerative Disc Disease
Degenerative disc disease is one type of back pain that
is caused by wearing away of the cushion that rests between
the vertebrae of our spine. The spinal column is made of
stacked bones called vertebrae. These bones are separated by
a cushion at each level called a spinal disc. The disc is a
tough but pliable tissue that helps maintain the position of
the spine, but also allows motion between the vertebrae.
With this design we have the stability to stand upright, but
also the flexibility to bend and twist. Unfortunately, these
discs can cause problems as they wear away.
As the disc ages, it becomes more brittle and less flexible.
The disc also becomes more prone to injury and degradation.
Exactly what causes pain with lumbar disc degeneration is
debatable, but we do know that some patients with worn out
discs have typical symptoms of low back pain.
It is important to understand that aging discs is normal!
MRIs of patients with no symptoms of back pain often show
wearing away of the discs. It should not be considered
abnormal to have wearing of the spinal discs. That said,
some patients can develop
symptoms of back pain, and it is possible that their
symptoms come from the spinal disc degeneration. It is very
important to have this carefully evaluated by your
orthopedic surgeon before embarking on any treatment
plan.
Low back pain is a significant cause of disability in
the U.S. and worldwide. It is estimated that 70% to 80% of
people will experience low back pain at some point in their
lives.
Artificial Disc Replacement
Artificial disk replacement is a newer surgical
procedure for relieving low back pain. Similar to
hip or
knee joint replacements, a disk replacement substitutes
a mechanical device for an intervertebral disk in the spine.
The device is meant to restore motion to the spine by
replacing the worn, degenerated disk.
Lumbar Fusion and Disk Replacement Surgeries
Lumbar fusion surgery remains the "gold standard" for
treating low back pain patients who are not helped by
nonsurgical methods. Although many people with
low back pain find relief with lumbar fusion, the
results of the surgery vary. For example, a patient with
spinal stenosis who has a fusion procedure may have a
very different outcome from a patient who has a fusion to
help back pain that is caused by disk degeneration.
In addition, some patients whose fusion surgeries heal
perfectly still end up with no improvement of their back
pain.
There are many reasons for the failure to improve after
fusion surgery, but some doctors believe it may be due to
the fact that fusion prevents normal motion in the spine.
Artificial disk replacement has emerged as an
alternative treatment option for
low back pain.
Who Is a Candidate for Disk Replacement?
To determine who is a good candidate for disk replacement,
the surgeon may require a few tests. These may include
magnetic resonance imaging (MRI), discography, computed
tomography (CT or CAT scan), and x-rays. These tests will
also help the surgeon determine the source of the pain.
Good candidates for disk replacement have the following:
- Back pain thought to be caused mostly from one or
two intervertebral disks in the lumbar spine
- No significant facet joint disease or bony
compression on nerves
-
Not excessively overweight
- No prior major surgery in the lumbar spine
- No deformity (scoliosis)
Disc Replacement Surgical Procedure
The surgical implantation procedure is performed through an
incision in the abdomen (similar to an
anterior lumbar interbody fusion).
With this approach, the organs and blood vessels must be
moved to the side. This allows your surgeon to access the
spine without moving the nerves. Usually, a vascular surgeon
assists the
orthopedic surgeon with opening and exposing the disk
space. Most surgeries take about 2 to 3 hours.
Disc Design
The disk replacement device may comprise the nucleus
(center) of the disk while leaving the annulus (outer ring)
in place, although this technology is still in an
investigative stage.
In most cases,
total artificial disk replacements substitute the
annulus and nucleus with a mechanical device that will
simulate spinal function. There are a number of different
disk designs. Each is unique in its own way, but all
maintain a similar goal: to reproduce the size and function
of a normal intervertebral disk.
Some of the disks are made of metal, while others are a
combination metal and plastic, similar to
joint replacements in the knee and hip. Materials used
include medical grade plastic (polyethylene) and medical
grade cobalt chromium or titanium alloy.
Rehabilitation for Lumbar Disc Replacement
Most patients are encouraged to stand and walk by the
first day after surgery. Because bone healing is not
required following an artificial disk implantation, the
typical patient is encouraged to move through the
mid-section. Early motion in the trunk area may translate
into quicker rehabilitation and recovery.
The typical hospital stay is 2 to 4 days, depending upon
pain control and return to function. Basic exercises during
the first several weeks after surgery include routine
walking and stretching while avoiding hyperextension
activities.
Patients can expect improvement of lower back pain and
disability in weeks to months following surgery. The results
from numerous studies, including FDA-regulated trials,
reveal that disk replacement improves, but does not
completely eliminate pain. It is critical that prior to
surgery the patient and the treating surgeon develop
realistic expectations of pain relief.
Research on the Horizon
The future of artificial disk replacement technology will
likely include significant advancements in the design of
implants, tools for diagnosis of the source of pain, and
other approaches to regenerating the disk to normal
function.
Where Are We Now?
A recent review in the journal Orthopedics Today reported
the findings of several European studies. These studies
found good results in about 75-85% of patients. This is
about the results expected with spinal fusion.
Unfortunately, these studies only lasted about one year, and
thus the long-term results are not well understood. More
research needs to be done before lumbar disc replacement is
a standard option for
degenerative disc disease, but it could be a future
treatment.
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