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Bone grafts for spinal fusion surgery
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To achieve a spinal fusion, a bone graft is used to promote two bones growing together
into one. The patient’s own bone will grow into and around 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, and a longer so-called ‘strut graft’ is used to bridge across multiple disc
spaces if a ‘corpectomy’ has been performed.
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There are several options available to patients and surgeons for bone grafts in
anterior cervical spine surgery: |
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Autograft bone for spinal fusion |
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Autograft bone (a patient’s own bone) is harvested from the iliac crest (hip). This
technique has been the gold standard since the 1950s. Autograft bone usually achieves
a fusion in 90%-95% of patients.
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The principal disadvantage with using autograft bone is that another incision needs
to be made over the hip to harvest the bone graft. Possible complications associated
with taking out bone graft include:
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Graft site chronic pain (which happens 10% to 25% of the time) |
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Infection |
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Bleeding |
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Damage to the lateral femoral cutaneous nerve (a sensory nerve that supplies sensation
to the front of the thigh) |
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Pelvis bone fracture |
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The chances of a complication increase with the size of the bone graft and patient
obesity. For those who opt to use an autograft, many patients find the bone graft
harvest site to be more painful than the cervical surgery site itself.
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Allograft bone for spinal fusion
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Allograft bone (a.k.a. ‘bank’ bone or donor bone from a cadaver) eliminates the
need to harvest the patient’s own bone. Basically, the donor graft acts as a bone
scaffolding onto which the patient’s own bone grows and eventually replaces over
years. There are no living cells in the bone graft, so there is little chance of
a graft ‘rejection’ like with an organ transplant. However, bone graft healing remains
an issue, as there is a somewhat greater likelihood of bone graft failure with allograft
compared to autograft. |
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With allografts, the speed of healing may be slower than an autograft bone fusion.
In addition: |
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In one-level spinal fusions, it yields nearly equivalent fusion rates as autograft
bone. |
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Anterior cervical instrumentation (plates & screws) are commonly employed with
allografts to increase fusion rates. |
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With increasing numbers of levels to be grafted/fused, the differences in fusion
rates between allograft and autograft become more significant. |
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There is a theoretical risk of transmission of an infection from a donor. The risk
of contracting a disease such as HIV or hepatitis from an allograft has been estimated
to be between 1 in 200,000 to 1 in 1 million. However, with modern procurement and
sterilization methods for bone tissue, the risk is essentially moot. |
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Potential risks and complications of a spinal fusion surgery include: |
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The principal risk from a spine fusion is that the graft does not heal. In general,
allograft bone does not heal quite as well as autograft bone, but both yield good
results when used in the anterior cervical spine. |
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If a graft is used without instrumentation, there is a small chance (1% to 2%) of
a graft dislodgment or extrusion. If this happens, another operation is necessary
to reinsert the bone graft, and instrumentation (plates) can then be used to hold
it in place.
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