|
Where does the new ligament come from?
Once you have decided to have
your ACL surgically reconstructed you should talk to your surgeon about
how he or she performs the surgery and what type of graft he/she likes
to use to reconstruct a torn ACL. During this surgical procedure, the
remnants of your torn ACL need to be removed, and a similar ligament from
somewhere else around your knee needs to be inserted in the place of the
original ACL.
Using a ligament from somewhere else around your knee may sound a bit
like robbing Peter to pay Paul, and in fact it is, for each of the grafts
that are used for ACL surgery has some drawbacks. The grafts that are
currently used today are the central part of the patellar tendon, some
of the hamstring tendons, or an "allograft" from a cadaver. The advantages
and disadvantages of these grafts are explained:
Patellar tendon -- for this type of graft, the central
1/3 of the patellar tendon is removed along with a small block of bone
at each end of the ligament. This creates a bone-patellar tendon-bone
graft. Some surgeons favor this graft because it was the first successful
graft to be used in modern ACL surgery, and the bone blocks at either
end are designed to allow the graft to be securely fixed and heal quickly
inside tunnels drilled in the femur and tibia. The patellar tendon connects
the patella to the tibia and is the tendon that allows the quadriceps
muscle to extend the knee. Removing a graft from the center of the patellar
tendon can result in inflammation of the tendon which can lead to patellar
tendinitis and anterior knee pain after surgery in some people.
Hamstring tendon -- the gracilis and semitendinosus muscles,
which are part of the hamstrings that help to flex your knee, have long
tendons that insert into the tibia just below the level of your knee
joint. These tendons can be removed, doubled over, and then used to
replace the ACL. These tendons are easier to harvest than the patellar
tendon, they require smaller drill holes in the femur and the tibia
for fixation, and they do not predispose patients to patellar tendinitis.
Most athletes never notice any decrease in strength or agility after
their hamstrings have been harvested. The drawback to this procedure,
however, is that hamstring grafts are more challenging to anchor in
the femur and tibia because they do not have blocks of bone at either
end.
Allograft --
a frozen piece of the patellar tendon from a human who has donated his
or her tissue to a tissue bank can also be used to reconstruct the ACL.
Using this graft has the obvious advantage of avoiding harvesting either
the patellar tendon or the hamstring tendons from the patient. The entire
surgical procedure can be done much faster. However, using this type
of a graft carries a very small risk of infection and the rate of graft
failure, or re-rupture, is probably higher than with the use of the
other two types of grafts.
Several factors influence what type of graft may be the best choice for
you and your surgeon. If you have a history of patellar tendinitis or
patellofemoral pain, or if you happen to have a very narrow or very short
patellar tendon, then a hamstring tendon graft may be necessary for you.
However, if the hamstring tendons are too small or not strong enough to
replace the ACL you may require either a patellar tendon graft or allograft.
Most surgeons develop a preference for one type of graft versus the others.
The graft that your surgeon chooses may be influenced by the practice
prevailing where he trained, but he might employ any of a number of alternative
techniques as well. While there is a lot of scientific debate at the moment
about what type of graft is the best, there is no clear answer to that
question. Each graft certainly has its place in today's surgical reconstruction
techniques. Across the United States today, most surgeries are done with
hamstring or patellar tendon grafts.
back to top
| back to ACL Surgery
| next page
|
