Posterior lumbar interbody fusion (PLIF) surgery
As with all spinal fusion surgery, a posterior lumbar
interbody fusion (PLIF) surgery involves adding bone
graft to an area of the spine to set up a biological
response that causes the bone to grow between the two vertebral elements and
thereby stop the motion at that segment.
Unlike the posterolateral gutter fusion, the PLIF
achieves spinal fusion in the low back by inserting
a bone graft and/or spinal implant (e.g. cage) directly
into the disc space. When the surgical approach for
this type of procedure is from the back it is called
a posterior lumbar interbody fusion (PLIF). A PLIF
fusion is often supplemented by a simultaneous posterolateral
spine fusion surgery.
Posterior lumbar interbody fusion surgery description
First, the spine is approached through a three-inch
to six-inch long incision in the midline of the back
and the left and right lower back muscles (erector
spinae) are stripped off the lamina on both sides and
at multiple levels.
After the spine is approached, the lamina is removed
(laminectomy) which allows visualization of the nerve
roots. The facet joints, which are directly over the
nerve roots, may then be undercut (trimmed) to give
the nerve roots more room. The nerve roots are then
retracted to one side and the disc space is cleaned
of the disc material. A bone graft, or anterior interbody
cages with bone, is then inserted into the disc space
and the bone grows from vertebral body to vertebral
body.
Doing a pure PLIF spine surgery has the advantage
that it can provide anterior fusion of the disc space
without having a second incision as would be necessary
with an anterior/posterior spine fusion surgery. However,
it has some disadvantages:
-
Not as much of the disc space can be removed with
a posterior approach (from the back).
-
An anterior approach (from the front) provides
for a much more comprehensive evacuation of the disc
space and this leads to increase surface area available
for a fusion.
-
A much larger bone graft and/or spinal implant
can be inserted from an anterior approach
-
In cases of spinal deformity (e.g. isthmic spondylolisthesis)
a posterior approach alone is more difficult to reduce
the deformity
-
There is a small but finite risk that inserting
a bone graft or cage posteriorly will allow it to
retropulse back into the canal and create neural
compression
PLIF surgery rates are higher than posterolateral
fusion rates because the bone is inserted into the
anterior portion (front) of the spine. Bone in the
anterior portion fuses better because there is more
surface area than in the posterolateral gutter, and
also because the bone is under compression. Bone in
compression heals better because bone responds to stress
(Wolff's law), whereas bone under tension (posterolateral
fusions) does not see as much stress.
PLIF spine surgery risks and complications
The principal risk of this type of low back surgery
is that a solid fusion will not be obtained (nonunion)
and further back surgery to re-fuse the spine may be
necessary. Fusion rates for a PLIF should be as high
as 90-95%.
Nonunion rates are higher for patients who have had
prior spine surgery, patients who smoke or are obese,
patients who have multiple level fusion surgery, and
for patients who have been treated with radiation for
cancer. Not all patients who have a nonunion
will need to have another spine fusion procedure. As
long as the joint is stable, and the patient's symptoms
are better, more back surgery is not necessary.
Other than nonunion, the risks of a spinal fusion
surgery include infection or bleeding. These complications
are fairly uncommon (approximately 1% to 3% occurrence).
In addition, there is a risk of achieving a successful
spine fusion, but the patient's pain does not subside.
By: Peter
F. Ullrich, Jr., MD
September 8, 1999 (Updated January 20, 2004)
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