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Surgical procedure (anterior cervical decompression)
Surgical approach
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The skin incision is about one inch,
horizontal and can be made on the left or right hand side of the neck
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The thin platysma muscle is then split in
line with the skin incision and the plane between the sternocleidomastoid
muscle and the strap muscles is then entered
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Next, a plane between the trachea/esophagus
and the carotid sheath can be entered
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A thin fascial layer (flat layers of fibrous
tissue) covers the spine (pre-vertebral fascia) which can easily be
dissected away from the disc space
Disc removal
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A needle is inserted into the disc space and
an x-ray is done to confirm that the surgeon is at the correct level of the
spine
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After correct disc space has been identified
on x-ray, the disc is removed by first cutting the outer annulus fibrosis
(fibrous ring around the disc) then removing the nucleus pulposus (soft
inner core of the disc)
Dissection
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Dissection is carried out from the front to
back to a ligament called the posterior longitudinal ligament. Often this
ligament is gently removed to allow access to the spinal canal to remove
any osteophytes (bonespurs) or disc material that may have extruded through
the ligament.
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The dissection is often performed using an
operating microscope to aid with visualization of the canal.
Surgical procedure (anterior cervical fusion)
To achieve a fusion, a bone graft is used to connect two bones
together. The patient’s own bone will grow into the bone graft and
incorporate the graft bone as its own. This process creates one continuous
bone surface and eliminates motion at the fused joint. A small piece of
bone is used to fuse a disc space.
There are different ways to get a bone graft:
Autograft bone (patient’s own bone) is taken from the iliac
crest (hip). The principal disadvantage with using autograft bone is that
another incision needs to be made over the hip to get the bone graft.
Chances of complication increases with the size of the bone graft. The
bone graft is an important part of the procedure. Many patients find the
site the graft is taken from to be more painful than the cervical surgery
itself.
Allograft bone (donor bone from a cadaver) eliminates the need to
take bone from the patient. Basically, the donor bone graft acts as a
calcium scaffolding into which the patient’s own bone grows. There
are no living cells in the bone graft, so there is no chance of a graft
rejection. This process, called “creeping substitution”, is
slower than an autograft bone fusion. In one-level fusions, it yields
equivalent fusion rates as autograft bone. If more than one level is fused,
it does not heal as well as autograft bone. To enhance the healing rate
– especially if more than one level is fused – many surgeons
combine allograft with anterior plating of the spine. If plating plus
allograft bone is used for a multi-level fusion, the fusion rate is
equivalent to autograft bone.
Bone graft substitutes
An anterior fusion can also be achieved by using one of the newer bone
graft substitutes. Although no current products are FDA approved specifically
for this indication, there are many products that can either mimic the
structure of bone (osteoconductive products) or start the fusion process
biochemically (osteoinductive). The anterior disc space lends itself well
to a bone graft substitute since it is a relatively easy site to obtain a
fusion (i.e. there is not a lot of stress in the cervical spine).
Currently, there are no bone graft substitutes that are structural, so they
usually have to be combined with a titanium cervical cage which gives the disc
space structural support.
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