|
|
Flatback
Syndrome |
 Balance
is achieved in the human spine by three curves in the
sagittal (side-view) plane. The normal cervical and
lumbar spine is lordotic or concave posterior. The
thoracic spine is convex posterior or kyphotic. The
S-shaped configuration of the spine in the sagittal
plane provides a shock-absorbing or spring like function
which reduces stress on the vertebral column when weight
loaded.
When
the human spine is balanced in the sagittal plane,
a plumb line dropped from the middle of the cervical
spine should fall near the middle of the last lumbar
segment. When any one of the curves increases or
decreases out of proportion to the other two, the
spine is thrown out of balance. The term flat back
refers to a relative decrease in lumbar lordosis
causing the spine and head to be decompensated forward.
An individual with flat back will plumbline well
anterior to the lumbar spine and pelvis.
Flat
back syndrome refers to the constellation of symptoms
experienced by an individual whose spine is forward
decompensated through decreased lumbar lordosis.
The most common clinical sign of this condition is
a tendency to lean forward when walking or standing.
Because it requires more energy to walk in a forward
decompensated position, the body will tend to right
itself.
Low
back, buttock and posterior thigh muscles are recruited
to tilt the pelvis in an attempt to bring the body
into better alignment. These muscles will commonly
fatigue, causing aching and pain. Hip and knee flexion
while standing and walking, is another mechanism
for aligning the spine in patients with loss of lumbar
lordosis. When hip flexion is used chronically to
stand erect, a hip flexion contracture can result
as the muscles in front of the hip shorten. Interestingly
enough, much of our awareness of flat back dates
from our early experience with surgical instrumentation
intended for the treatment of thoracolumbar scoliosis
and degenerative spine disease. The Harrington rod
and other similar devices produce correction of scoliotic
lumbar deformities by utilizing distraction or lengthening
forces in the concavity of the curve. |
Although
the curve is straightened in the front view plane,
the same distraction forces applied to the concavity
of the curve in the side view plane produce straightening
of the lumbar lordosis and forward decompensation
of the spine.
Although
flat back syndrome was initially seen most commonly
in patients with distraction-type instrumentation,
loss of lumbar lordosis may occur in several other
ways. During the aging process, for example, inter
intervertebral disks lose water, degenerate and shrink;
as the height of the spinal column shortens, lumbar
lordosis may be lost. Compression fractures, most
commonly caused by osteoporosis, can also flatten
the curve of the lower spine and cause similar symptoms.
In
many individuals, lack of lumbar lordosis does not
produce symptoms. Those patients who are symptomatic
however, can be treated. Most patients with symptomatic
flat back should be treated initially with physical
therapy. The emphasis of therapy should be on strengthening
of the gluteal, low back, abdominal and hamstring
musculature. Cardiovascular conditioning cannot be
overemphasized as a method for improving pain tolerance.
Since
symptoms are produced through abnormal mechanics
of the spine, pelvis and upper legs, a brace intended
to support a decompensated spine would have to cross
each of these structures. Such braces are not usually
effective. Similarly, trunk braces, which also capture
the leg are not well tolerated by most individuals.
In general, bracing is not an option for symptomatic
flat back. When conservative methods fail and the
patient is symptomatic to the point of being dysfunction
due to the pain, surgery is indicated.
Flat
back occurs most commonly in patients who have
had previous spinal fusions. To recreate balance,
it is necessary to break the fusion mass (osteotomy)
and re-fuse the spine in a more balanced position.
Particular techniques for osteotomy depend on the
considerations such as the cause of the flat back,
the presence of residual scoliosis and a patients'
general medical condition. While many osteotomies
can be done through a posterior (back) approach
only, other may require both a front and back surgery. |
The
surgical treatment of flat back is typically demanding.
Many patient have long standing disability which renders
them in less than optimum condition for surgery. Most
patients have had previous surgery leaving them with
soft tissue and, in many cases, nerve scarring. For
these reasons, surgical complications occur more frequently
in these patients than those undergoing surgery for
the first time.
- Surgical
treatment is normally less demanding in patients
with small scoliotic curves, those with previous
fusions for degenerative conditions or who have
loss of lumbar lordosis due to inflammatory diseases
such as ankylosing spondylitis.
- Since
these patients need correction only in the sagittal
plane, it is usually possible to operate through
one exposure from the back. At our center, we have
been successful with an adaptation of the decancellation
procedure described by Thomasen.
- In
this procedure, an osteotomy is performed below
the Conus Medullaris or the lowest most extent
of the spinal cord, usually at the L3 level.
At the L3 level, there are only nerve roots in
the spinal canal and because they are more pliable,
surgery is less traumatic than it at higher levels
where the spinal cord is less tolerant of movement
and manipulation. In this procedure, the posterior
bone at the L3 level is completely removed and
the spongy contents of the vertebra is loosened
and extracted. Pressure on the pelvis causes
the spine to crack, closing the osteotomy and
producing increased lumbar lordosis. Fixation
devices, such as pedicle screws, rods and hooks
are used to maintain correction. Bone graft is
placed which ultimately heals producing a new
fusion at the osteotomy site. We have been successful
in producing 20-40 degrees of correction using
this method.
|
 |
 |
This
52 year old male came to Dr. Pashman after five
previous spine surgeries. He had a chronic, painful,
stopped position. Dr. Pashman performed a posterior
lumbar pedicle subtraction, closing osteotomy
and instrumentated fusion from T10-L5. The patient's
symptoms were resolved. |
|
In
those patients who have scoliosis and flat back syndromes
in the lumbar region, or any other deformity which
produces decompensation left or right of the middle
of the pelvis a three-dimensional correction is necessary
to achieve spinal balance. Both anterior and posterior
approaches are necessary in these patient. Discectomies
or osteotomies in the front of the spine are performed
at one or more levels, followed by standard osteotomies
in the posterior spine. The instability that we can
obtain by this type of circumferential surgery creates
the opportunity to correct the spine both in the frontal
and sagittal plane. A greater degree of correction
can also be obtained from front and back surgery which
may be necessary in any patient whose flat back requires
more than 20-40 degrees of correction. Front and back
surgery is also augmented with spinal fixation devices,
the placement of bone graft and in many cases the application
of a brace postoperatively. At our Center, most front
and back surgeries are performed under one anesthesia
(same day), enabling us to mobilize patients quickly
during the postoperative period.
Many patient
and their families ask "to what degree with the scoliotic
curve be corrected by surgery?" However, the more
important issue when contemplating scoliosis surgery
is "will the progression of the curve be stopped
and will spinal balance be achieved with surgery?" Spinal
instrumentation is a powerful tool for the correction
of spinal deformities, but it must be used with an
appreciation for both frontal and sagittal plane
alignment in the production of balance. Early use
of these devices in the thoracolumbar spine considered
only frontal plane deformity and in many individuals
flat back was the result. Today, because of widespread
attention to maintenance of lumbar lordosis by experienced
spinal surgeons, the incidence of flat back is decreasing.
1.
Pashman RS, Lonstein JE, Bradford DS, et al: Moe's
Textbook of Scoliosis and Other Spinal Deformities
3rd Edition. Ankylosing Spondylitis W.B. Saunders
Company, Philadelphia, Penn., 1994.
2.
Thomasen E: Vertebral osteotomy for correction of
kyphosis in ankylosing spondylitis. Clin Orthop 194:142
- 152, 1985 April 9, 1996 |
| |
Related
links:
Flatback
cases performed by Dr. Pashman
Read an article about Flatback Syndrome written by Dr. Pashman
Revision Surgery
Posterior Spinal Fusion
Abnormal Spinal
Anatomy
Spinal Balance
Back FAQ's
|
|
