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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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