Replacement Therapy: How Cartilage is
Host: Dr. Linda Austin –
Dr. Linda Austin: I’m Dr.
Linda Austin. I’m interviewing Dr. David
Geier who is Director of the MUSC Sports Medicine Clinic and an
orthopedist. Dr. Geier, one of the new
techniques is cartilage replacement therapy or surgery. What, exactly, is that?
Dr. David Geier: Well, this
is a really exciting avenue of new technology in sports medicine. Let me start by saying, this is really not
intended as a new procedure necessarily for arthritis. Arthritis is breakdown of cartilage,
especially in the knee, but that’s more of a global problem throughout the
knee. What we’re really talking about
is, especially in your young patient and your young adults, where they have
small focal areas of cartilage damage through an injury or wear and tear; they
have a small area where there’s articular cartilage loss. We’re talking about new techniques to
regenerate cartilage, which has never really been something we’ve been able to
do until the last 5, 10 years.
Dr. Linda Austin: So, which
joints, in particular, are commonly the site for this kind of procedure?
Dr. David Geier: The one
that’s been studied the most and has been worked on the most is the knee
because that’s where most of the problems are.
If you think of your athletes, your weekend warriors, that run and lift
weights, they do a lot of pounding on their knees. So, that’s where most of this has
started. But some of these techniques
that we’ll talk about are being applied to the elbow, the ankle, especially,
and we’re starting to hear reports of using them in the shoulder and, finally,
and probably least commonly, in the hip.
Dr. Linda Austin: I guess
to begin to understand this process, a first question would have to be, what,
exactly is cartilage?
Dr. David Geier:
Absolutely. That’s a good
question. One of my colleagues tells
patients that cartilage is the white stuff at the end of a chicken bone. And he’s exactly right. It’s the kind of spongy, smooth surface at
the ends of the bones. It helps the
joint surfaces glide smoothly through a range of motion. But that cartilage can break down. There’s no blood supply to cartilage and it’s
very susceptible to injuries, through a bad joint injury or wear and tear.
Cartilage doesn’t re-grow on its own. Once it’s injured, it’s gone. So, that’s been one of the problems with
injury to articular cartilage. It
doesn’t come back. So, we’re looking for
ways, not to replace a whole joint surface of cartilage, because these
techniques don’t work for that, to replace small areas of cartilage. And there are three of four different
procedures now that are done to do that.
Dr. Linda Austin: So, walk
us through one of the more common procedures that you use this technique for.
Dr. David Geier: The one
that has gotten the most attention in the press, and that’s related to its
frequency of use in the NFL and the MBA, among our really elite, professional
athletes, is this procedure called a microfracture. There are numerous players throughout
multiple leagues that have had this done.
What this procedure is, especially with the knee, if you get a small
area of cartilage damage, maybe about the size of a dime, where the cartilage
is injured and it’s gone, where it’s exposed, and now you have exposed bone in
that small area, what we can do, surgically, with a small area like that is
take this little microfracture awl, essentially, they look like fancy ice
picks, is, essentially, poke holes in the bone.
You, almost, drill holes about three to four millimeters apart, and you
drill deep enough that the bone, which does have a blood supply, starts to
bleed, and that blood creates an inflammatory response that the body converts
Now, this cartilage is not the same type of cartilage as the
articular cartilage that’s in the knee.
It makes more of a fibrocartilage.
But it’s thought to work pretty well at giving at least some smooth
surface to fill that defect. Now, the
trick comes when the lesions get bigger than that, you know, more than, maybe,
the size of a dime. That’s when we go to
some of our other procedures. One of
those would be a procedure where you take cylinders of bone and cartilage from
another part of your knee, from a non-weight bearing part of your knee and
actually plug it into the other part of your knee. You’re usually transferring it to an area
that does bear a lot of weight, a lot of the stress of walking and running.
So, if you take your own cylinder of bone and cartilage out,
that’s thought to fill that hole and make a smooth surface. If it’s big enough, sometimes you actually
have to use bone and cartilage, use a
cylinder of bone. This is when it gets
to, you know, the size of a quarter or half dollar. But you actually take it from a cadaver. When a person dies, or there’s a donor, you
size match it to the patient and fill a very large defect in their knee with a
cylinder of bone and cartilage.
Dr. Linda Austin: Where
does the cartilage come from?
Dr. David Geier: When
you’re taking the cartilage from another spot in your knee, what you’re taking
are these little dowels, so to speak, and you make a cylinder. You’re taking it, usually, from above your
kneecap, in an area that has articular cartilage, but your knee doesn’t use
that to bear weight. So, you’re taking
it from yourself, and you take it with the bone under it because the bone heals
where the defect was, the defect in the bone is what actually gets it to heal,
and then the cartilage makes a smooth surface.
The same thing goes when you use a cadaver or a donor graft. The cartilage is already on the surface of
the knee joint and then you’re just taking a cylinder, you know, about a 10, 12
millimeter-thick cylinder of bone and cartilage.
Dr. Linda Austin: What are
some of the complications of this procedure?
Dr. David Geier: Like any
procedure, I think one of the big things is making sure that you communicate
with your surgeon and that you’re an appropriate candidate for that
procedure. This, again, is, one, not for
generalized osteoarthritis, and, two, these are very big surgeries. You have to protect these to get them to
heal. It may involve two to three months
of being on crutches where you’re not putting weight on it. It may require the patient to be in a
machine, for four, six hours a day, that bends your knee. A lot of that can be done while you’re
sleeping, but it slowly bends your knee back and forth to stimulate lubrication
of the joint to get the cartilage to heal.
And, then, the knowledge that it may not work, and you may need a
different procedure down the road.
Having said that, the success rates seem to be very good.
Dr. Linda Austin: Dr.
Geier, you used the word earlier, articular cartilage. I gather that there are different kinds of
Dr. David Geier: Yes. I probably need to simplify that. The articular cartilage is the cartilage on
the ends of the bones, the white stuff on the ends of the chicken bones, so to
speak, the smooth cartilage on the ends of the bones. Now, that’s more of a location. You’re absolutely right that there are
different types of cartilage. And that
gets to some of these procedures, which type of cartilage are they
creating? There’s hyaline cartilage. The hyaline cartilage is the type of
cartilage that’s in a healthy, mature knee.
It’s the smooth, gliding cartilage that has the properties that make it
very resistant to wear and impact forces.
On the other hand, there’s the fibrocartilage, which is a different type
of cartilage, more brittle, not quite as durable. That is the type of cartilage that is made
with that microfracture procedure that we talked about.
Our goal is to replace, or create, hyaline cartilage, which is,
essentially, the more long-lasting durable cartilage, such as when we took the
bone and cartilage from another part of the knee, transferring that type of
cartilage to another spot, or to use one of our groundbreaking techniques, the
chondrocyte transplantation. All of
those are ways to recreate hyaline articular cartilage, the durable
Dr. Linda Austin: What’s
new on the horizon, any exciting, new techniques in this area?
Dr. David Geier: I think
there’s one technique we’ve somewhat imported from Europe
that really seems to be an exciting avenue of true cartilage replacement. And that’s what’s called an autologous
chondrocyte implantation. That’s a big
fancy way of saying, taking a small amount of cartilage from a part of your
knee that has non-weight bearing cartilage, sending that small piece of
cartilage off to a lab. The one we use
is a lab in Boston. They take the cartilage and grow the
chondrocytes, or the precursor cells, that become cartilage in the body. You grow these cells. It comes back as a test tube of cells of your
own precursor cartilage cells and then you go back into surgery, open up the
knee, and you put those cells back into the knee, into where there’s a defect
of cartilage. You put them under a layer
of fibrous tissue that you harvest from the leg through a small incision. So, it’s under, sort of, a thin patch of
tissue. Those cells, in theory, then,
over the next 6 to 12 months, re-grow into normal articular cartilage.
We discussed the microfracture, when you poke the holes, it
creates a type of fibrocartilage, which is good, it’s better than none at all,
but it’s thought to break down over time.
In theory, the chondrocyte transplantation, where you take the cells and
that makes cartilage, could potentially make the true hyaline articular
cartilage that you’re born with. So,
this is a very exciting avenue of research.
There’s a long way to go to see how well this works. But it is a procedure that people train and
learn how to do and, in the right circumstance, it could be, potentially, a
Dr. Linda Austin: Dr.
Geier, thank you so much for talking with us today.
Dr. David Geier: Thank you
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