Fusion/Instrumentation
Surgery
for the spine involves a variety of approaches and techniques.
The purpose of this discussion is to briefly explain what
those procedures are and why the surgeon might chose one
or several in attempting to help you.
First
know that a laminectomy is not a discectomy is not a
fusion is not an instrumentation.
A
laminectomy is a removal of the roof of bone over the
surface of the spinal cord and involves an incision
on the back or back of the neck. A laminectomy is performed
to either decompress the underlying nerve or spinal
cord or to gain access to the inside of the spinal column
so that the surgeon can remove disc or tumor. A laminectomy
can sometimes be combined with a removal of a portion
of the facet to further decompress the nerve or to gain
further surgical access for the rest of the procedure.
The
disc material is the wafer like cushion that is in between
the round blocks of vertebral bodies. With degeneration
or injury, the covering around the discs can tear and
disc material exudes out and presses upon the nerve.
Even in the absence of this herniation, there can be
significant degeneration of the disc and the edges of
the vertebral body to create severe episodes or even
constant spinal pain. Discectomy can be accomplished
in several ways. If there is a herniated fragment, the
surgeon can perform a small laminectomy (laminotomy)
and remove the fragment. Many times the surgeon can
chose to remove more disc material within the disc space
in an effort to prevent more material from herniating
out later. Not all discectomies require an approach
from the back however. The approach that a surgeon chooses
for the disc problem is tailored to the anatomical location
of the herniation (cervical, thoracic, or lumbar), whether
the degeneration or herniation is central or lateral,
and the degree that the disc is pressing upon the spinal
cord. After carefully reviewing everything, your surgeon
may choose to bring in another surgical specialist such
as a thoracic surgeon or a vascular surgeon to assist
him or her in the approach to the disc. This would be
more likely if the approach to the disc or the vertebra
was being made from the front (anterior) or the side
(lateral) in the chest or abdomen.
A
fusion is the placement of bone in a joint space to
prevent that joint from moving. This is done when it
is felt that the movement is counterproductive or even
dangerous for the patient. In these cases the patient
can have severe degeneration of the disc and vertebral
body such that movement in the particular area constantly
elicits pain or neurological deficit. A fusion can also
be necessary in the face of major spinal cord trauma.
With fracture of the major supporting bone of the spinal
column and tearing of the ligaments, instability of
the spine and associated endangerment of the spinal
cord and nerve roots can require surgical stabilization
to include fusion. Fusion can also be required when
a large amount of bone and joint has been destroyed
by infection or tumor. In many of these cases removal
of that bone will result in instability to the spine
unless new bone is placed within or over the defect
to fuse that segment. The bone used for fusion can be
taken from the patient by taking a graft of bone from
another part of the body (e.g. hip, rib, tibia) or from
a cadaver donor (allograft). More recently, surgeons
have found that fusion can augmented and accelerated
by using synthetic compounds (hydroxyapitite) or special
proteins (bone morphogenic protein) from the patient's
blood.
Instrumentation
is a surgical process that many times goes hand in hand
with fusion. Instrumentation is a general term indicating
that some form of metal was applied to the spine during
the surgical procedure. The metal is generally titanium
because it is lightweight, very strong, and better able
to be visualized in the MRI. The forms that instrumentation
takes are diverse and designed to fit any spinal problem
that the surgeon faces. It includes metal plates with
screws and bolts designed to strut the front of two
vertebral bodies, interpedicular screws to bore into
the vertebral body and be interconnected with a rod
to prevent motion of two segments, and cages that are
placed within the disc space and filled with morcelized
bone to create a fusion. The decision as to what type
of instrumentation to use or whether to use it at all
rests with the surgeon and his or her experience when
confronting a particular complex spine problem.
Many
times one of the abovementioned procedures will require
the use of another or perhaps all of the above mentioned
spinal procedures. When undergoing a spinal surgery,
or any surgery for that matter, have clear understandings
of the following: What is wrong and what exactly will
be corrected. Is there a limit to what can be corrected
(i.e. is back pain that has occurred for 25 years going
to disappear after the surgery)? What are the indications
for doing this particular surgery that is recommended?
What are the goals of the surgery? What are the risks
of the surgery? What are the alternatives to the surgery?
What is involved with the convalescence? What about
return to work, school, and exercise? If you have questions
regarding the surgical procedure that is proposed for
you, do not hesitate to call your surgeon or make another
appointment to clarify any issue that you might have.
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