After
a retractor is used to pull aside fat and muscle, the
lamina is exposed. Part of it is cut away to uncover
the ligamentum flavum - a ligament that supports the
spinal column (Fig. 4).
Entering
the Spinal Canal
Next
an opening is cut in the ligamentum flavum through
which the spinal canal is reached. The compressed
nerve is now seen, as is the cauda equina (bundle
of nerve fibers) to which it is attached. The cause
of compression may now also be identified - a bulging,
ruptured or herniated disc, or perhaps a bone spur (Fig.
5).
Sometimes
a fragment of disc has moved away from the disc space
to press on the nerve root as it leaves the spinal
canal (Fig. 6). This will often cause more
severe symptoms. Because of its distance from the
disc space, the fragment may not be seen on a myelogram,
and a CT scan (computerized x-ray) may be required
to locate it.
Removal
of the Herniated Disk
The
compressed nerve is gently retracted to one side,
and the herniated disc is removed. As much of the
disc is taken out as is necessary to take pressure
off the nerve (Fig. 7). Some surgeons will
remove all "safely available" disc material. After
the cause of compression is removed, the nerve can
begin to heal. The space left after removal of the
disc should gradually fill with connective tissue.
Fusion
and Instrumentation
|
Surgery for lumbar laminectomy is performed
with the patient lying on his abdomen or side. A small
incision is made in the lower back (Fig. 3). 
The operation is completed when
the incision is closed in several layers (Fig. 8).
Unless absorbable suture material is used, the skin sutures
(stitches) will have to be removed after the incision
has healed. 