Lumbar spinal
fusion is nearly a
century old
operation. It was
done in antiquity
mainly for
infectious
complications those
being mostly
tuberculosis in
cause. Now spinal
fusion is a commonly
performed operation.
Numerous indications
for fusion exist.
The goal of fusion
is to eliminate the
functional spinal
unit - that is, to
eliminate any motion
between a vertebral
body-disc-vertebral
body segment. This
may be as a result
of a fracture which
leads to instability
with the subsequent
risk of neurological
injury or spinal
instability. It
could result from
degeneration such as
age related
arthritis which
results in abnormal
spinal motion or
even nerve
compression. It may
be as a result of
infection which
erodes the normal
architecture of the
spine thereby
requiring a
stabilizing fusion
to prevent any
further collapse and
subsequent
neurological injury.
Routinely fusion is
performed during the
correction of a
deformed spine such
as scoliosis or
kyphosis.
Increasingly fusion
is done for
discogenic back pain
defined as the pain
mediated by the
intervertebral disc.
Fusion involves
the use of
autogenous bone
harvested from the
patient generally
from the pelvis.
Occasionally
allograft from a
cadaver can be used
although the fusion
rate is known to be
lower. Adding
instrumentation such
as screws, rods,
threaded interbody
cages, or plates
will increase the
rigidity at the
fusion site and
therefore enhance
the likelihood of
obtaining a solid
fusion. Factors
which diminish
fusion rates include
smoking, diabetes,
instability, use of
allograft bone,
multiple levels, and
poor surgical
technique.
