The intervertebral fusion cage is another tool for the spine surgeon
to use in helping treat various low back problems. For patients that
require fusion surgery to treat degenerative disc disease, the
intervertebral fusion cage has been shown to be effective for several
reasons.
- Low complication rate
- Minimized pain after surgery due to less trauma during surgery
- Shorter hospital stay compared to other types of fusion methods
- Quicker return to daily activities
The cage is not designed to treat all types of spinal problems. You
may be a candidate if your pain is from degenerative disc disease with
segmental instability.
The intervertebral fusion cage is a hollow cylinder. The cages are
made from various materials including metal or carbon graphite fiber.
Doctors place bone graft inside the cylinder. The holes in the cage
keep the graft in contact with the bony surface of the vertebrae. This
ensures that the bone graft unites with the vertebrae, forming a solid
fusion.
The cage helps in several ways. The solid cage separates and holds
two vertebrae apart. This makes the opening around the nerve roots
bigger, relieving pressure on the nerves. As the vertebrae separate,
the ligaments tighten up, reducing instability and mechanical pain. The
cage also replaces the problem disc while holding the two vertebrae in
position until fusion occurs.
The intervertebral fusion cage is a fairly new device. However, it
has been studied in the U.S. for over ten years. There have been well
over 10,000 procedures performed using intervertebral fusion cages, and
it has proven to be a safe procedure. Several of the devices have been
approved for use by the United States Food and Drug Administration
(FDA).
Cages can be implanted from the front or back of the spine. Surgery
from the back of the spine may be needed to remove bone spurs or a
herniated disc into the spinal canal. In these instances, the cages can
be implanted from the back, without having to make an additional
incision in the patient's abdomen.
Most often, the cages are put in during surgery through the front of
the spine. Working from the front can be done with an open procedure,
where a large incision is made through the abdomen. This procedure is
being perfected with the use of a laparoscope, a TV camera that allows
the doctor to see inside the abdominal cavity while working on the
spine. This method only requires a few small incisions, which seems to
help patients heal and get moving faster after surgery. Using a
laparoscope for this procedure is difficult and may not be possible in
all cases.
To see and work on the problem disc from the front, the surgeon
makes an incision in the abdomen. The size of the incision depends on
whether a laparoscope will be used. Organs and vessels are carefully
moved aside. The problem disc is located using another type of special
instrument called a fluoroscope (a special X-ray machine that shows the
images on a TV screen).
In most cases, two cages are placed side by side to replace one
disc. The surgeon drills two holes through front of the disc. Before
putting one cage into each hole, the doctor prepares the cages. Bone
graft may be taken from your pelvis bone through a small incision on
your side. A second incision may not be needed if your surgeon uses a
bone graft substitute.
The doctor packs the cages with the bone graft and inserts the cages
side by side into the drill holes. A fluoroscope is used to make sure
the cages are in the correct position. The abdominal incisions are sewn
together, completing the surgery.
