Total Ankle Allograft Transplant Replacement
The procedure which will be discussed
below is an ankle allograft transplant replacement using a fresh graft
of the ankle harvested from a cadaver. Although there are other alternative
surgical choices, each operation has clear advantages and disadvantages
and the success rates of these various operations are different. These
decisions are not always easy for the patient to make. The final decision
should be made with an orthopedic surgeon who has considerable experience
in the management of ankle arthritis. This experience is very important.
Studies have shown that the successful results of surgery increase
and complication rates decrease with greater surgical experience.
The results of ankle allograft replacement are good but not always
predictable. With an ankle arthrodesis, the joint is fused or glued
together, limiting the up and down movement. An ankle allograft replacement,
however, allows a more normal “function,” though the movement
may not be perfect. The main advantage of the allograft ankle replacement
is the return of some freedom of movement in the ankle. This movement
is important for walking, exercise and climbing type activities. Full
movement of the ankle joint is not likely regained, however, is far
preferable to the lack of movement in the fused ankle. The success
rate of the allograft replacement has been good. There are potential
for complications like any other operation including skin healing
problems, changes in the nerves on the skin with numb patches, and
continued arthritis. Perhaps the specific problem of the allograft
replacement is that the bone and cartilage which is transplanted does
not heal, and further arthritis develops. If this happens, another
allograft replacement may be performed, or one can convert this to
a more traditional total ankle replacement, or even an ankle fusion.
The recovery following the allograft ankle replacement is very carefully
monitored. Rehabilitation and exercise are essential. Dr. Myerson’s
approach to rehabilitation includes an exercise bicycle and therapy
in a swimming pool. This begins as soon as the stitches are removed
and the incision is healed. These exercises facilitate the range of
motion and ultimately improve the final outcome of the allograft joint
replacement procedure.
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This is the up and down movement of the ankle that one would expect
following an ankle allograft replacement.
In an ankle allograft replacement, an entirely new joint surface (made
of bone and cartilage from a fresh cadaver) is implanted instead of
replacing the ankle joint with a replacement made of metal and plastic.
This procedure offers a unique alternative to the management of ankle
arthritis without “burning any bridges.” Although we have
not been performing this procedure for more than a few years, the
short term results are very encouraging.
The main advantage of this type of procedure is the potential for
replacement of the entire ankle joint with viable living cartilage
cells. In the cases we have performed so far there does not appear
to be any immune response or rejection of the implanted material.
It seems that unlike other transplanted tissue, there is not sufficient
bone or cartilage for this to be recognized as foreign and then rejected.
The most important aspect of the transplant is the correct sizing
to perfectly match the ankle.
The operation involves removal of a segment of bone and cartilage
from the arthritic ankle, and then the identical bone cuts are made
on the ankle cadaver graft using specialized instruments which cut
the graft in the exact size and shape. This operation involves a very
specialized team of ankle reconstructive surgeons as well as a good
working bone bank to provide the donor graft required for implantation.
Once you have been accepted as a candidate for the allograft ankle
replacement, you will be put on a waiting list. It may take anything
from one week to one year to find the exact donor for your ankle.
This does not depend on tissue matching as for example must be done
with other organ transplants. Instead, we have to obtain a perfect
size match for your ankle. This takes a lot of work on the part of
the bone graft company with which we work.
Once you are put on the waiting list for the allograft ankle replacement,
we ask that you are available at all times to have your surgery. This
may inconvenience you, but it takes a lot of work on the part of the
bone graft company to find the perfect match for you, and we do not
want this to be wasted. Once a graft size match has been identified
we are notified by the company, and then the graft is subjected to
very stringent infection testing. This is extremely important, and
neither we nor the company will perform any graft unless this has
been completely cleared medically. This may take up to three weeks
to clear infection control adequately. We try not to involve you in
this process until the graft has been released, but this can be difficult,
since you will need to make travel, family and work arrangements.
For this reason, we will often inform you of the availability of a
size match early on, but you will have to understand that the majority
of grafts do not pass through infection control. This can be very
frustrating, but is better than finding out at the last moment, when
you are unable to arrive in time for the surgery. Once the graft has
been released to us, we must implant it immediately, since the success
of the allograft replacement depends upon the presence of living cartilage
cells. These have a limited life span, and for this reason, we want
to perform the surgery as soon as possible once the graft is released
to us. We therefore ask that once you are on the list, that you inform
us immediately if your home or work circumstances change such that
you will not be able to go through with the surgery in the near future.
In a total ankle allograft replacement, an entirely new joint surface
(made of bone and cartilage from a fresh cadaver) is implanted instead
of replacing the ankle joint with a replacement made of metal and
plastic. This essentially amounts to what can be considered a transplant
of a new ankle, since the fresh bone and cartilage is transplanted
from a cadaver, replacing the arthritic ankle which is removed completely.
The advantage of this type of procedure is the potential for replacement
of the entire ankle joint with viable living cartilage cells. This
procedure offers a unique alternative to the management of ankle arthritis
without “burning any bridges.” It is a procedure which
is probably the most exciting of all treatment options available for
managing ankle arthritis, in that if it works, the patient has as
normal an ankle as possible under the circumstances.
Not everyone is a suitable candidate for this ankle transplant procedure.
The patient who is ideally suited for this operation is younger and
much more active. Since the total ankle replacement works well, particularly
for the older individual, DR Myerson rarely uses the ankle transplant
for the elderly more sedentary individual. It is used more specifically
for the younger patient who would normally require an ankle fusion
(arthrodesis), but for whom there are complicating features where
an ankle fusion is not the ideal operation. This is particularly the
case in patients who have ankle arthritis in both ankles, where a
fusion of both ankles is really debilitating. The other scenario which
is a problem is in the patient who has arthritis of both the ankle
and other additional joints in the back of the foot, so that if an
arthrodesis has to be performed, it would have to be more extensive.
The ankle allograft transplant operation requires a very specialized
team of ankle reconstructive surgeons as well as a good working bone
bank to provide the donor graft required for implantation. What happens
with the patient who may be eligible for this procedure is that following
a careful examination, the size of the ankle is measured by computer
analysis, and the measurements are then sent digitally to a company
which harvests the ankle from a cadaver. Extremely strict precautions
are taken to ensure that this process is completely sterile, and that
there is no infection possibly present in the transplanted tissue.
The infection screening process is even more rigorous than that taken
by companies which are involved in blood transfusions.
Once the ankle has been measured, the data is sent to the tissue bank,
which then begins a search for the exact size. Unfortunately this
can take some time, and patients may have to wait for more than six
months until the correct size has cleared the screening process. The
recovery after the ankle allograft transplant is very similar to that
after total ankle replacement. Interestingly, there is no rejection
of the graft as may occur in other transplant cases, since the volume
of tissue transplanted has little immunogenic potential. In the cases
performed thus far there has not been any immune response or rejection
of the implanted material. Below is an example of the surgical procedure.
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Above on the left is a cutting jig which is used to harvest the ankle
joint from the cadaver ankle. The block is fixed on to the cadaver
and the precise cuts are made to remove the ankle joint which is then
implanted as can be seen on the right hand picture, with a healthy
new ankle in place.
In the above pictures, the ankle allograft transplant is being checked.
The up and down movement of the ankle is being tested, and one can
see that normal motion of the ankle has been established for this
patient.
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