For Ewing’s sarcoma and other types of sarcomas, treatment can sometimes include surgery
to remove a tumor. That can also mean removing part — or even all — of
the bone it’s attached to. Options for replacing a lost bone include
metal implants called endo-prostheses, autografts (bones that come
from the patients themselves) and allografts (bones from donors).
Here, Justin Bird, M.D., shares seven things he wants
you to know about allografts.
Where does MD Anderson get the
donor bones for its allografts?
There are a few companies that source specimens, prepare them for
use, and make them available to doctors and hospitals.
Do the bones come from people who have donated their bodies to science?
No. They come from organ donors. Tissue banks are able to use many
different types of donated organs, including bones, for transplants.
Does a patient’s blood type have to match the donor’s in order
to receive an allograft?
No. All living cells are removed from the bones before they’re used,
so the patient’s body just treats them as a structure to grow on. That
said, we do try to choose allografts that best match the patient’s
height, size, gender and build.
Why would a patient elect to get an allograft rather than,
say, an endo-prosthesis?
There are a number of reasons, including the location of the
affected bone in the body and the involvement of soft tissue. In the
early days of endo-prosthetics, there was nothing to help a bone hold
onto a metal surface when you used an implant to repair a bone defect.
Now, we have metal surface options with porous coatings. Living bone
sees the small holes in the metal as opportunities for in-growth. But
there are some challenges associated with attaching various structures
(such as a tendon) to metal, so we still use allografts in some situations.
How do you know when an allograft is successful?
We get X-rays and CT scans to look for healing between the allograft
and patient’s bone. Allografts work because the body treats them like
scaffolding. It can recognize that type of structure and grow into it.
A patient’s tissue won’t grow through the entire thing, but if we can
get that healing at the edges, it’s enough to maintain the structural
integrity of a reconstruction.
Is it possible for patients to get a bone graft from themselves?
Yes, that’s called an autograft. Tumors can show up in any part of
the skeleton, so surgeons may have the option of taking part of a
non-weight-bearing bone from the patient to reconstruct what was
removed. The fibula is a very good donor bone. It’s the smaller of the
two leg bones below the knee, and it’s non-weight-bearing, so we can
remove it without causing significant functional changes.
What types of advances are you seeing in this field?
Our plastic surgeons are experts in vascularized bone grafts, which
come from the patients themselves. We take a bone — again, usually the
fibula — along with its blood supply, and use it to repair defects in
the spine, pelvis, mandible or other areas. Orthopedic surgeons place
the graft where they want it, and then plastic surgeons sew the blood
vessels together at the new site. Moving the bone along with its blood
supply helps patients heal much faster.
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