Posterior lumbar interbody fusion (PLIF)
The principle of this operation is similar to the
anterior lumbar interbody fusion (ALIF)
except that the implant (fusion cage or bone) is implanted through the back,
instead of approaching through the abdomen.
On the left, a the fusion cages are seen from the
posterior approach, in this translucent model. On the right, they are
seen from the side.
The advantage of this approach is that the nerves of
the lumbar spine can be visualized, and decompressed, if needed.
Although they can be decompressed from the anterior approach (through the
abdomen), this is a much more cumbersome and tedious process.
The disadvantage of this approach is that, in order to
place the fusion, a substantial amount of bone, including part of the
facet joint, must be removed. This removal
of supporting joint and bone acts to destabilize a spine we are trying to
fuse and stabilize. In addition, we know that the interbody method of
fusion requires a relatively large cage be placed, in order to distract and
spread the interspace apart as much as possible, without tearing the
connecting ligaments. From the posterior approach, this sometimes
extensive bone removal, and often one is tempted not to place as large a
cage as possible because of the nerve root retraction necessary. From
the anterior approach this is not an issue.
Another disadvantage of the posterior approach,
alluded to in the previous paragraph, is that retraction upon the nerve
roots in the lumbar spine is necessary in order to place the cage.
This places the nerve roots at some risk from stretching.