Fusion with Interbody Cages
A Patient's Guide to Anterior Lumbar Interbody Fusion with Intervertebral Cages
Back pain is a very common problem that may affect up to 80% of the population
at some time during life. The vast majority of back problems get better without
needing any type of surgical procedure. There are many different causes of back
pain. The specific cause of your back problem will need to be determined before
any type of surgery will be suggested as a treatment option. To learn more about
how your back works and various treatments that are available, you may want
to review the document, entitled:
A new type of surgical treatment is now available for patients who have been
unsuccessful at controlling their back pain with non-surgical treatments. The
procedure uses a new type of device called an intervertebral fusion cage to
perform a spinal fusion between two or more vertebrae in the lumbar spine (the
This document will discuss:
- The lumbar spine anatomy
- The rationale for the surgery
- How the surgery is performed
- Some of the devices that are used
- The use of bone graft
- What to expect during your rehabilitation
- Some possible complications
To better understand how a lumbar spinal fusion is performed, it helps to know
some anatomy of the overall spine, and more specifically the parts of the spine
that are involved in the surgery: the lumbar spine, pedicles, nerve roots, and
Please review the document, entitled:
What type of back problems is the intervertebral fusion cage used for? One
of the most common causes of chronic back pain is degenerative disc disease.
Degenerative disc disease occurs when the intervertebral disc between two vertebrae
begins to wear out. The degeneration probably starts after an injury to the
disc, or many small injuries to the disc over time. Degeneration of the disc
usually takes several years to occur. The process of degeneration causes the
disc to lose its ability to act as a shock absorber between the vertebrae. The
disc becomes thinner and allows the vertebrae to move closer together. As the
vertebrae grow closer, the openings (foramina) in the back of the spine where
the nerve roots leave the spinal canal become narrower. This can lead to pinching
and irritation on the nerves, which causes pain into the legs.
The problem is made worse by the development of segmental instability. Segmental
instability is a term used by spinal surgeons to describe what occurs when the
disc degeneration allows more movement between the vertebrae than normal. This
movement, or instability, can cause mechanical pain in the back and further
irritation on the nerve roots. The intervertebral cage was designed to make
it easier for surgeons to perform a spinal fusion to treat the problem of degenerative
If you would like further information about degenerative disc disease, you
may wish to review the separate document, entitled:
The intervertebral fusion cage is a large, hollow cylinder made of some type
of metal, usually titanium. It is designed as a "cage" so that bone graft can
be placed inside the hollow cylinder to allow a spinal fusion to occur between
two vertebrae. The holes that are throughout the cage allow bone to form around
and through the cage connecting the two vertebrae with solid bone.
Many of the newer types of intervertebral fusion cages are also designed to
allow performing the spinal fusion either using an open incision or a laparoscopic
procedure. An open incision is the traditional way of performing surgery, where
larger incisions are made to allow the surgeon to see where he is operating
and perform the procedure. A laparoscopic procedure is performed using much smaller
incisions and using a special TV camera inserted into the abdomen to allow the
surgeon to see where he is operating and perform the procedure. The laparoscopic
approach can be much less damaging to normal tissue and can speed recovery.
On the other hand, the laparoscopic approach is sometimes very difficult to perform
and may not be possible in all cases.
The intervertebral fusion cage is designed to do several things. First, the
cage is used to spread the two vertebrae apart, which allows several things
to occur. The openings in the back of the spine where the nerve roots leave
the spine become larger - making more room for the nerves. This decreases the
pinching and irritation on the nerves. The strong ligaments that surround the
disc tighten as the cage forces the vertebrae back apart. This decreases the
segmental instability between the two vertebrae and decreases the mechanical
pain in the spine. Second, the intervertebral fusion cage sits between the two
vertebrae to replace the disc and hold the two vertebrae in the correct position
until a fusion occurs between the vertebrae.
Simply because you have back pain does not mean you need surgery. Your doctor
will try many other options to treat your back pain before suggesting surgery.
The intervertebral fusion cage is not designed to treat all spinal problems
requiring surgery. Your doctor will carefully assess whether or not you are
a candidate for the procedure. If your major problem appears to be degenerative
disc disease combined with segmental instability of the spine, you may be a
candidate at some point in your treatment for surgery with the intervertebral
Intervertebral fusion cages are designed to be used in several different ways.
One way is by making an incision in the back of the spine and inserting the
cage between the vertebrae from the back side. This is usually done if you need
to have other surgery done at the same time to remove bone spurs or a herniated
disc from the spinal canal. More commonly, the procedure is done from the front
of the spine using either an open incision - or the laparoscopic approach, as
described above. It is not uncommon for the surgeon to start out using the laparoscope
and have to stop and perform the surgery through an open incision. This usually
occurs because the surgeon cannot see well enough with the laparoscope.
To perform the operation from the front, either the laparoscope is inserted
or an open incision is made so that the surgeon can see the front of the spine.
The disc that is to be replaced with the intervertebral fusion cage is located
using a fluoroscope (a fluoroscope is a special X-ray machine that shows the
images on a TV screen). In most cases, two intervertebral fusion cages are used
in each disc and are placed side by side using special instruments. Two holes
are drilled into the disc to place the intervertebral fusion cages side by side.
The fluoroscope is used throughout the procedure to visualize the use of the
Bone graft is then placed inside the hollow intervertebral fusion cage. This
bone graft will probably be taken from your pelvis through a small incision.
The cage will then be inserted into place between the vertebrae. The second
intervertebral fusion cage is placed in the same way. Once the fluoroscope is
used to ensure that the intervertebral fusion cages are placed in the correct
position, the operation is over.
To learn more about what bone graft is and how it is used, please review the
You will spend about two days in the hospital recovering from your surgery.
While you are there, an orthotic specialist will visit you to fit you with a
custom brace. You will be required to wear the brace for approximately two to
three months following surgery, or until proper fixation of your new intervertebral
fusion cages occurs. This process varies in time depending upon how each person
advances with his or her recovery.
Once you go home, we encourage a gradual return to normal activities starting
with early ambulation wearing your new custom fitted brace. Driving privileges
will be restricted for the first two weeks after your surgery and will resume
upon the doctor's approval.
You are encouraged to begin aerobic exercises, such as walking, as soon as
possible after your surgery. Your goal is to resume many of the activities you
were doing before your surgery, but in a gradual progression.
Since your intestines have been manipulated during the procedure to gain exposure,
they may not work normally for a few days following surgery. We recommend small
meals for the first few days, gradually increasing to your normal portions.
For your convenience, we have provided a set of post-operative instructions.
This page can be downloaded and printed if you lose the copy you received when
you were discharged. This document includes things you should do - and things
You will probably be sent for outpatient physical therapy (PT) for a period
of up to six to twelve weeks. There, a physical therapist will do an evaluation
of your needs and tailor a specific exercise program for you to follow. They
will illustrate these exercises and make sure you are doing them properly. They
will also provide you with an exercise program that you can do while at home.
The physical therapy staff reports directly to your doctor, keeping him or her
aware of your progress.
What are the success rates?
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. Several of the devices have been
approved for use by the United States Food and Drug Administration (FDA).
With any surgery, there is a risk of complications. When surgery is done near
the spine and spinal cord these complications (if they occur) can be very serious.
Complications could involve subsequent pain and impairment and the need for
additional surgery. You should discuss the complications associated with surgery
with your doctor before surgery. The list of complications provided here is
not intended to be a complete list of complications and is not a substitute
for discussing the risks of surgery with your doctor. Only your doctor can evaluate
your condition and inform you of the risks of any medical treatment he or she
Injury to the Spine or Nerves
When operating around the spine, injury to the nerves around the spine is always
a possibility. In the study mentioned above, there were nerve injuries in 2.7%
of the patients. It is twice as common to have nerve problems after a posterior
approach - mainly because the surgeon is operating closer to more of the spinal
Injury to Blood Vessels Causing Bleeding
The large blood vessels that lead to the legs lie right in front of the spine
where the intervertebral fusion cage is inserted. In many cases, the vessels
must be moved aside to perform the surgery. Performing the anterior fusion through
either the anterior open approach or the laparoscopic approach can result in
damage to the blood vessels in the abdomen, and can lead to bleeding problems.
You may require a blood transfusion. Excessive bleeding is also one of the main
reasons that the surgeon will have to stop performing the procedure with the
laparoscope and switch to an open incision. This is not uncommon. In most research
studies of the procedure major injury to blood vessels occurred in only 1% of
the cases reviewed.
Implant migration is a term used to describe the fact that the intervertebral
fusion cage has moved from where the surgeon placed it initially. This usually
occurs fairly soon after surgery - before the healing process has progressed
to the point where the cage is firmly attached by scar tissue or bone growth.
If the cage moves too far it may not be doing its job of stabilizing the two
vertebrae. If it moves in a direction towards the spine or large vessels, it
may damage those structures. If you have a problem with implant migration, your
surgeon may have to perform a second operation to replace the cage that has
Infection is a possibility in every type of surgery. You will probably be
given antibiotics before surgery and for a short time after surgery to reduce
the risk of infection.
Thrombophlebitis, sometimes called Deep Venous Thrombosis (DVT), can occur
after any operation. DVT occurs when the blood in the large veins of the leg
forms blood clots within the veins. This may cause the leg to swell, become
painful, and warm to the touch. If the blood clots in the veins break apart,
they can travel to the lung, where they are lodged in the capillaries of the
lung and cut off the blood supply to a portion of the lung. This is called a
pulmonary embolism (pulmonary means lung; embolism means fragment of something
traveling through the vascular system). Most surgeons take preventing DVT very
seriously. There are many ways to reduce the risk of DVT. Probably the most
effective is getting you moving as soon as possible!
Surgery of the spine continues to be a challenging and difficult area. The
intervertebral fusion cage is another tool for the spine surgeon to use in helping
treat the various problems occurring in the low back. For patients that require
surgery to treat their degenerative disc disease, the intervertebral fusion
cage has been shown to be effective for the following reasons:
- The procedure has been found to have a low overall complication rate.
- Postoperative pain may be minimized through a decrease in the amount of
- Operative procedures and lengths of stay in the hospital can be less than
other fusion methods.
- Return to daily activities can be much quicker.
Copyright © 2003 DePuy Acromed.
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