WHAT IS IT? HOW IS
The spine is made
up of a series of bones called “vertebrae”; between each vertebra
are strong connective tissues which hold one vertebra to the next, (i.e.
the disc) and acts as a cushion between the vertebrae. The disc allows
for movements of the vertebrae and lets people bend and rotate their neck
and back. The type and degree of motion varies between the different levels
of the spine: cervical (neck), thoracic (chest) or lumbar (low back).
The cervical spine is a highly mobile region that permits movement in
all directions. The thoracic spine is much more rigid due to the presence
of ribs. The lumbar spine allows mostly forward and backward bending movements
(flexion and extension).
Fusion is a surgical
technique in which one or more of the vertebrae of the spine are united
together (“fused”) so that motion no longer occurs between
them. The concept of fusion is similar to that of welding in industry.
Spinal fusion surgery, however, does not weld the vertebrae during surgery.
Rather, bone grafts are placed around the spine during surgery. This may
be done on the back (commonly) or on the front (less commonly) of the
spine. The body then heals the grafts over several months – similar
to healing a fracture – which joins, or “welds”, the
IS FUSION NEEDED?
There are many potential
reasons for a surgeon to consider fusing the vertebrae. These include:
treatment of a fractured (broken) vertebra; correction of deformity (spinal
curves or slippages); elimination of pain from painful motion; treatment
of instability and treatment of some cervical disc herniations.
One of the less controversial
reasons to do spinal fusion is vertebral fracture. Although not all spinal
fractures need surgery, some fractures – particularly those associated
with spinal cord or nerve injury – generally require fusion as part
of the surgical treatment.
Certain types of spinal
deformity, such as scoliosis, are commonly treated with spinal fusion.
Scoliosis is an “S” shaped curvature of the spine that sometimes
occurs in children and adolescents. (for more info, see www.srs.org).
Fusion is indicated for very large curves or for smaller curves that are
Sometimes a hairline
fracture allows vertebrae to slip forward on one another. This condition
is called spondylolisthesis. (see North American Spine Society patient
education brochure on Adult Isthmic Spondylolisthesis), and can be treated
by fusion surgery.
that is treated by fusion surgery is actual or potential instability.
Instability refers to abnormal or excessive motion between two or more
vertebrae. It is commonly believed that instability can either be a source
of back or neck pain or cause potential irritation or damage to adjacent
nerves. Although there is some disagreement on the precise definition
of instability, many surgeons agree that definite instability of one or
more segments of the spine is an indication for fusion.
Cervical disc herniations
that require surgery usually need not only removal of the herniated disc
(discectomy), but also fusion. With this procedure, the disc is removed
through an incision in the front of the neck (anteriorly) and a small
piece of bone is inserted in place of the disc. Although disc removal
is commonly combined with fusion in the neck, this is not generally true
in the low back (lumbar spine).
Spinal fusion is sometimes
considered in the treatment of a painful spinal condition without clear
instability. A major obstacle to the successful treatment of spine pain
by fusion is the difficulty in accurately identifying the source of a
patient’s pain. The theory is that pain can originate from painful
spinal motion, and fusing the vertebrae together to eliminate the motion
will get rid of the pain. Unfortunately, current techniques to precisely
identify which of the many structures in the spine could be the source
of a patient’s back or neck pain are not perfect. Because it can
be so hard to locate the source of pain, treatment of back or neck pain
alone by spinal fusion is somewhat controversial. Fusion under these conditions
is usually viewed as a last resort and should be considered only after
other conservative (non-surgical) measures have failed.
IS FUSION DONE?
There are many surgical
approaches and methods to fuse the spine, and they all involve placement
of a bone graft between the vertebrae. The spine may be approached and
the graft placed either from the back (posterior approach), from the front
(anterior approach) or by a combination of both. In the neck, the anterior
approach is more common; lumbar and thoracic fusion is usually performed
The ultimate goal
of fusion is to obtain a solid union between two or more vertebrae. Fusion
may or may not involve use of supplemental hardware (instrumentation)
such as plates, screws and cages. Instrumentation is sometimes used to
correct a deformity, but usually merely acts as an internal splint to
hold the vertebrae together while the bone grafts heal.
Whether or not hardware
is used, it is important that bone or bone substitutes be used to get
the vertebrae to fuse together. The bone may be taken either from another
bone in the patient (autograft) or from a bone bank (allograft). Fusion
using bone taken from the patient has a long history of use and results
in predictable healing. Autograft is currently the “gold standard”
source of bone for a fusion. Allograft (bone bank) bone may be used as
an alternative to the patient’s own bone. Although healing and fusion
is not as predictable as with the patient’s own bone, allograft
does not require a separate incision to take the patient’s own bone
for grafting, and therefore is associated with less pain. Smoking, medications
you are taking for other conditions, and your overall health can affect
the rate of healing and fusion, too.
Currently, there is
promising research being done involving the use of synthetic bone as a
substitute for either autograft or allograft. It is likely that synthetic
bone substitutes will eventually replace the routine use of autograft
or allograft bone.
With some of the newer
“minimally invasive” surgical techniques currently available,
fusion may sometimes be done through smaller incisions. The indications
for minimally invasive surgery (MIS) are identical to those for traditional
large incision surgery; however, it is important to realize that a smaller
incision does not necessarily mean less risk involved in the surgery.
LONG WILL IT TAKE TO RECOVER?
The immediate discomfort
following spinal fusion is generally greater than with other types of
spinal surgeries. Fortunately, there are excellent methods of post-operative
pain control available, including oral pain medications and intravenous
injections. Another option is a patient-controlled post-operative pain
control pump. With this technique, the patient presses a button that delivers
a predetermined amount of narcotic pain medication through an intravenous
line. This device is frequently used for the first few days following
fusion surgery is generally longer than for other types of spinal surgery.
Patients generally stay in the hospital for three or four days, but a
longer stay after more extensive surgery is not uncommon. A short day
in a rehabilitation unit after release from the hospital is often recommended
for patients who had extensive surgery, or for elderly or debilitated
It also takes longer
to return to a normal active lifestyle after spinal fusion than many other
types of surgery. This is because you must wait until your surgeon sees
evidence of bone healing. The fusion process varies in each patient as
the body heals and incorporates the bone graft to solidly fuse the vertebrae
together. The healing process after fusion surgery is very similar to
that after a bone fracture. In general, the earliest evidence of bone
healing is not apparent on X-ray until at least six weeks following surgery.
During this time, the patient’s activity is generally restricted.
Substantial bone healing does not usually take place until three or four
months after surgery. At that time activities may be increased, although
continued evidence of bone healing and remodeling may continue for up
to a year after surgery.
The length of time
required off work will depend upon both the type of surgery and the nature
of your work. It can vary from approximately 4-6 weeks for a single level
fusion in a young, healthy patient with a sedentary job to as much as
4-6 months for more extensive surgery in an older patient with a more
physically demanding occupation.
In addition to some
restrictions in activity, a brace is sometimes used for the early post-operative
period. There are many types of braces that might be used. Some are very
restrictive and are designed to severely limit motion, while others are
intended mainly for comfort and to provide some support. The decision
to use a brace or not, and the optimal type of brace, depends upon your
surgeon’s preference and other factors related to the type of surgery.
Following spinal fusion
surgery, a post-operative rehabilitation program may be recommended by
your surgeon. The rehabilitation program may include back strengthening
exercises and possibly a cardiovascular (aerobic) conditioning program
and a comprehensive program custom-designed for the patient’s work
environment in order to safely get the patient back to work. The decision
to proceed with a post-operative rehabilitation program depends upon many
factors. These include factors related to the surgery (such as the type
and extent of the surgery) as well as factors related to the patient (age,
health and anticipated activity level). Active rehabilitation may begin
as early as 4 weeks post-operatively for a young patient with a single
CAN I EXPECT IN THE LONG RUN?
Although fusion can
be a very good treatment for some spinal conditions, it does not return
your spine to “normal”. The normal spine has some degree of
motion between vertebrae. Fusion surgery eliminates the ability to move
between the fused vertebrae, which can put added strain on the discs and
below the fusion. A fusion will however not usually leave you with any
‘feeling’ of stiffness once the wound is fully healed. Fortunately,
once a fusion has healed it rarely, if ever, breaks down. However, it
does place more stress on the discs next to the fusion. This may have
some potential to accelerate degeneration of those segments, but this
risk varies between individuals. Many surgeons therefore recommend that
spinal fusion patients avoid repetitive strenuous activities that involve
combined lifting and twisting manoeuvres to minimize the stress on the
areas around the fusion.
The decision whether
or not to undergo spinal fusion is complex and involves many factors related
to the condition being treated, the age and health of the patient, and
the patient’s anticipated level of function following surgery. This
decision must therefore be made carefully and should be discussed thoroughly
with your surgeon.
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