Paul & Sue Liles
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Surgery #2 - Curvature Correction And Instrumentation
Curvature of the spine, or scoliosis, can be caused by
congenital, developmental or degenerative problems. However, at present,
the vast majority of cases of scoliosis actually have no known cause.
An 11 hour operation resulted in Sue's back being returned to an "S"
instead of a "C" and the rotation from 50 degrees to approximately 14
degrees!!!!!
It is important to note that scoliosis is not usually a cause of back
pain. The condition represents a deformity of the spine but is not
usually painful. Of course, people with scoliosis can develop back pain,
just as most of the adult population can develop back pain. However, it
has never been found that people with idiopathic scoliosis (the most
common form of scoliosis) are any more likely to develop back pain than
the rest of the population. People with degenerative scoliosis can
develop pain from osteoarthritic joints.
Scoliosis usually develops in the thoracic spine (upper back) or the
thoracolumbar area of the spine, which is between the thoracic spine and
lumbar spine (lower back). It may also occur just in the lower back. The
curvature of the spine from scoliosis may develop as a single curve
(shaped like the letter C) or as two curves (shaped like the letter S).
Scoliosis surgery
For those who cannot stay functional despite aggressive conservative
treatment, surgery may be considered. In Sue's case, surgery was
mandatory.
Most patients will not need
surgery for their scoliosis, as the curves tend to either not progress
or to progress at a very slow rate. The progression is typically no more
than 1 to 3 degrees per year, so it takes many years of observation to
see any significant progression of the curve in an adult.
Also, because
the curve is in the lumbar spine, progression of the curve is very
unlikely to influence the lungs or heart (as it would in the thoracic
spine).
Therefore, unlike surgery for idiopathic scoliosis, the goal of
surgery for degenerative scoliosis is not to prevent deformity as much
as it is to treat pain.
Seeing The Screws
Spinal fusion is the most widely performed surgery for scoliosis. In
this procedure, bone (either harvested from elsewhere in the body (autograft),
or donor bone (allograft) is
grafted to the vertebrae so that when it heals, they will form one
solid bone mass and the
vertebral column becomes rigid.
This prevents worsening of the curve at the expense of spinal movement.
This can be performed from the anterior (front) aspect of the spine by
entering the
thoracic or
abdominal cavity, or performed from the back (posterior). A
combination of both is used in more severe cases.
Xrays
Originally, spinal fusions were done without metal implants. A
cast was applied after the surgery, usually under
traction to pull the curve as straight as possible and then hold it
there while fusion took place. Unfortunately, there was a relatively
high risk of
pseudarthrosis (fusion failure) at one or more levels and
significant correction could not always be achieved. In 1962, Paul
Harrington introduced a metal spinal system of instrumentation which
assisted with straightening the spine, as well as holding it rigid while
fusion took place. The original, now obsolete
Harrington rod operated on a ratchet system, attached by hooks to
the spine at the top and bottom of the curvature that when cranked would
distract, or straighten, the curve. A major shortcoming of the
Harrington method was that it failed to produce a posture where the
skull would be in proper alignment with the pelvis and it didn't address
rotational deformity. As a result, unfused parts of the spine would try
to compensate for this in the effort to "stand up straight".
As the
person aged, there would be increased "wear and tear", early onset
arthritis, disc degeneration, muscular stiffness and pain with eventual
reliance on painkillers, further surgery, inability to work full-time
and disability. "Flatback" became the medical name for a related
complication, especially for those who had lumbar scoliosis.
Modern spinal systems are attempting to address
sagittal imbalance and rotational defects unresolved by the
Harrington rod system. They involve a combination of rods, screws, hooks
and wires fixing the spine and can apply stronger, safer forces to the
spine than the Harrington rod. Spinal fusion is rarely performed without
this instrumentation.