Low back pain is a significant problem that affects many Americans. Today,
we have several procedures to treat patients who have failed all non-operative
management. Recently, the Food and Drug Administration (FDA) approved an artificial
disc for the treatment of
low back pain (CHARITÉ™
Artificial Disc, DePuy Spine,
Inc.). In addition, other
artificial disc devices developed by other companies
expect to be FDA-approved and subsequently come to market. These devices will
provide surgeons options when selecting an
artificial disc device.
Disc Replacement Explained
Artificial disc replacement is the actual removal of the disc (intervertebral
disc) through an incision made through the abdomen(anterior approach). The
disc is completely removed and the prosthesis (artificial disc) is positioned
and implanted between the two vertebral bodies.
Spinal Anatomy: A disc lies between two vertebral
bodies; this may be called a ‘motion segment’
This prosthesis is analogous to one used in knee or hip replacement. These
devices are often a metal-on-metal design that restores and maintains normal
motion. The benefit of artificial disc replacement is that it maintains normal
spinal motion and spares the patient from having the 'motion' segment fused.
To explain this further, in the lumbar spine there are five motion segments.
Each motion segment consists of two bones (vertebrae) with a disc in between.
Located behind the vertebrae and discs are small joints (facet joints). The
facet joints are similar to joints elsewhere in the body that allow the motion
of bending forward and backward.
Goals and Benefits of Artificial Disc Replacement
The goal of an artificial disc is to remove the pain generator; that
being a degenerated or damaged disc. After the degenerated disc is removed,
the artificial disc is implanted into the empty space and maintains the motion
of that particular motion segment. The benefits include:
1. Avoids disrupting the segment above or below the disc, which preserves
the natural anatomy of the unaffected lumbar discs.
2. Allows the surgeon to restore normal disc height and post-operatively
allows the patient more flexibility to bend forward, backward, and rotate
or twist.
Disc Replacement: Better than Spinal Fusion?
Total disc or artificial disc replacement is not a soft material and an artificial
disc does not restore or replace a human disc. An artificial disc is a prosthetic
device made from metal and is sometimes designed with a plastic liner or core
that helps to maintain the body's ability to flex and extend. Through the FDA's
trial studies, it was found that patients who underwent artificial disc replacement
did experience a quicker post-operative return to normal functional activity.
This is definitely a benefit.
However, artificial disc replacement is not for all patients with low back
pain and it does not replace the need for spinal fusion. Lumbar spinal fusion,
which is a common treatment for patients with low back pain who have failed
non-operative management, is effective in reducing pain. The disadvantage of
spinal fusion is it limits the patient's range of motion and may transfer stress
to the discs above and/or below the fused segment.
Making Decisions
Patients who are interested in exploring artificial disc replacement as a treatment
option should seek a well-qualified surgeon with vast experience in performing
anterior (through the stomach) spine surgery. Artificial disc replacement is
similar to any major surgical procedure. There are possible complications that
include unresolved back pain, prosthesis failure, bowel or bladder problems,
and the need to revise the prosthetic device at a later date.
Technology Marches On
The clinical trials, those presently completed, have proven that artificial
disc replacement not only maintains spinal flexibility, but also reduces pain
and restores function to patients who suffer low back pain. No doubt -- future
improvements in technology and surgical techniques, along with a better understanding
of natural anatomy, will expand the indications for use of total disc replacement.
