Lumbar Disc Herniation
Introduction 
The spine is composed of 33 vertebrae, uniquely aligned to support
the body and provide a passageway for the spinal cord and nerves.
At the top of the spine are seven cervical (neck) vertebrae, followed
by 12 thoracic (chest) vertebrae from which the 12 pairs of ribs
originate. Next are 5 lumbar (low back) vertebrae, followed by the
5 fused sacral bones (the back of the pelvis) and 4 fused bones
of the coccyx (tailbone).
What is lumbar disc herniation?
 Vertebrae
are separated from each other by intervertebral discs which
lie between the bony vertebral bodies of the spine, cushioning
the vertebra and providing space for the nerves roots to exit
the spinal canal. The disc and vertebral bodies are considered
joints since there is motion.
 The
discs are composed of cartilage that have an outer wall of tough
fibrous tissue called the annulus fibrosus, and a softer, inner
portion called the nucleus pulposus. The nucleus pulposus is
a jelly-like substance that contains water which, like a water-
filled balloon, gives cushioning to the disc. If a disc degenerates
(a herniated disc), it flattens and puts pressure on the spinal
cord. Because the space between the vertebrae also becomes less,
the bones may put pressure on the nerves.
What causes a lumbar disc herniation?
 The
natural curvature of the spine provides the skeleton with strength
and stability. The curves act like a spring in a coil and distribute
the mechanical stress as the body moves. Unfortunately, because
the lumbar spine carries the bulk of the body's weight, it is
more prone to injury. As discs age, they lose their water content
and begin to degenerate. The annulus fibrosus (outer ring),
may also be damaged through general wear and tear or by injury
in which the nucleus, under extreme pressure, bulges out through
the annulus fibrosus ring.
Can lumbar disc herniation be prevented?
Most lumbar disc herniations occur in 30 to 50 year-old people
– when we are physically active and busy, sometimes too busy
to take care of ourselves. Confining our physical activity to what
our bodies are prepared for is a key to preventing injuries. The
answer to this dilemma is to prepare our bodies for what we want
to do. Consistent and rational exercise, maintaining good body weight,
good posture (especially holding the abdomen in) and good nutrition
all support good back health. Accident prevention involves assessing
risks – is your body prepared for the activity you are about
to do?
What surgical treatment options are there for lumbar disc herniation?
BAK Fusion Cages
  A
device called a "cage" is used to hold spinal grafts
in place while the healing occurs.
The procedure is performed under general anesthesia. The doctor
uses a fluoroscope (live-action xray)to help mark the areas to be
fused and to aid assessment of the physiologic (normal) curve of
the spine, disc height, and accurate placement of the cages. Then
one-third to one-half of the articulating facets (the extensions
on the vertebrae) are removed; this allows the cages to be inserted
with minimal damage to the nerve roots. Using a microscope or other
magnification, the doctor identifies the nerve roots in the epidural
space. Then the disc material is removed. Using dilators of increasing
diameters, the vertebral bodies are separated to obtain a satisfactory
disc height. Threads are cut into the opposing vertebral surfaces
using a bone tap. The cage is then screwed into this space and packed
with the patient's own bone material.
ALIF (Anterior Lumbar Interbody Fusion)
In the ALIF procedure, an anterior approach to the spine
(the incision is made in the abdominal area, in front) allows complete
removal of an intervertebral disc. Once the disc is removed, the
space is filled with bone (sometimes held in place by a cage or
other device) to obtain a spinal fusion.
PLIF (Posterior Lumbar Interbody
Fusion)
Posterior Lumbar Interbody Fusion (PLIF) is a surgical
technique that involves removing an intervertebral disc and creating
a spinal fusion in the lumbar spine through one incision in the
back. The procedure involves making an incision in the midline of
the back. After incising (cutting into) the middle of the layer
of muscle and ligament that sits on either side of the spine, the
attachments to the spinous process and lamina are freed. Using a
special instrument that removes small bites of bone, the lamina
is gradually removed until the doctor can see the nerves. The nerves
are then gently moved slightly to expose the intervertebral disc.
Using various instruments, the disc is removed through the right
and left sides of the spinal canal and the intervertebral space,
which has been cleared, is then packed with bone graft and a bone
block or cage implant. Instrumentation, such as pedicle screws,
are used to provide support for the fused vertebrae. Additional
bone graft may be placed to ensure a solid fusion.
TLIF (Transforamenal Lumbar Interbody
Fusion)
Transforamenal Lumbar Interbody Fusion (TLIF) is a
surgical technique that involves removing an intervertebral disc
and creating a spinal fusion in the lumbar spine through one incision
in the back. It is similar to a PLIF except that the disc removal
is performed through an approach that is more lateral (to the side).
In some cases only one side of the disc needs to be exposed (right
or left) in order to perform the procedure.
The procedure involves incising (cutting) into the middle of the
layer of muscle and ligament that sits on either side of the spine,
and freeing the attachments to the spinous process and lamina. Using
a special instrument that takes small bites off bone, the lamina
is gradually removed to expose the nerves. Using various instruments,
the disc is removed through the right and left sides of the spinal
canal (although sometimes all this can be done through one side
only) and the intervertebral space which has been cleared is then
packed with bone graft and either a bone block or cage implant.
Instrumentation, such as pedicle screws, is then placed in the vertebrae
to secure it. Additional bone graft will often be placed across
the transverse processes to ensure a solid fusion.
Intradiscal Electrothermal Therapy
(IDET)
IDET therapy is a new and minimally invasive procedure
for treating pain due to disc degeneration. The technique involves
delivering controlled levels of thermal energy (heat) to a section
of a degenerated disc through a fine wire. This heat causes contraction
and thickening of the disc wall, resulting in contraction or closure
of disc fissures (small tears).
Laminotomy
When the spinal canal becomes narrowed or the nerves
compressed, a laminotomy can be performed to free up the space of
the spinal canal by removing a portion of the lamina. The procedure
involves making an incision into the layer of muscles and ligaments
that sits on either side of the spine, and freeing up the attachments
to the spinous process and lamina to expose the laminae to full
view. Using a special instrument that removes little bites of bone,
the lamina is gradually trimmed until sufficient bone is removed
to free the compressed nerve This "unroofs" a portion
of the spinal canal and resulting in enlargement of the space available
for the nerves.
Laparoscopic Fusion
 Many
patients require spinal fusion surgery to stabilize the vertebrae
and alleviate severe, chronic back pain. Traditionally, spinal
fusion has been performed as open surgery, and while it has
been associated with a low complication rate and pain relief
for 90% of patients, many patients experienced back pain and
fatigue as a result of muscle loss from the operation.
In 1993, a minimally invasive way to perform spinal fusion surgery,
called laparoscopic spinal fusion, was developed by Dr. Regan. By
using endoscopes and special instrumentation, laparoscopic spinal
fusion requires only a small incision in the back. There are numerous
benefits including reduced hospital stay and recuperation time.
Patients undergoing laparoscopic surgery are hospitalized for just
under 2 days, versus the 4 to 6 days required for patients undergoing
open surgery.
Artificial Disc Replacement
 Dr. Regan performs ADR procedures and previously preformed them as part of an Federal
Drug Administration clinical trial. When performing artificial
disc replacement (ADR), the doctor inserts a small prosthetic
(artificial) disc comprising a polyethylene core that slides
between two metal end plates.
The end plates are attached to the vertebral body with anchoring
teeth built along the rim of the end plates. The prosthetic discs
replace the injured discs, helping to relieve chronic back pain.
The polyethylene core allows movement of the spine, unlike fusions
which prevent normal movement.
The disc is made of the same material used in artificial hips
and knees.
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John
J. Regan, M.D.