Description:
Kevin R. Stone, M.D., discusses the meniscus: what it is, why it
is important, and what to do if you injure it. Followed by a patient
Q&A. 12:19 minutes/11.3MB |
|
I am Dr. Kevin Stone, orthopaedic surgeon at The Stone
Clinic in San Francisco, and this lecture on the meniscus cartilage was
recorded on January 25, 2006.
Today, we are talking about the knee joint’s meniscus. The meniscus
is the shock absorber inside a knee joint that is very frequently injured
in sports activities. The shock absorber is a fibrous cartilage that sits
between the femur and the tibia. There is a medial meniscus, meaning the
inside one, and a lateral meniscus, an outside meniscus. The shock absorbers
permit the knee joint to go through one – three million steps per
year at up to five times body weight without the joint wearing out, under
normal activity.
The fibrous shock absorbers, when injured, produce a rough surface inside
the knee, which causes catching, locking, buckling, pain, or any combination
of the above symptoms inside the knee joint. The meniscus can be injured
in sports and twisting activities, such as planting a foot on a soccer
field and then being hit from the side, or it can be injured in simple
activities, such as getting out of the car, placing the foot on the ground,
stepping up and twisting on the knee, and feeling a sudden catch or pop.
When injured, the meniscus is most commonly torn. If it is torn in a clear,
clean pattern, it can frequently be repaired arthroscopically. If it is
torn in a complex or degenerative pattern, it very often needs to be trimmed.
How the meniscus is treated determines the outcome for the knee joint.
For instance, if a person injures his knee by twisting it and suffering
a torn meniscus and then lives with the knee pain, catching, locking, or
giving way for many months, that meniscus will be beaten up, torn, and
degenerated. This will often cause a wear pattern against the opposing
articular cartilage, the covering of the bone inside the joint. That wear
pattern is what we call arthritis. Then, if a patient presents to a surgeon
with a complaint of knee pain, catching, popping, and/or giving way, and
a surgeon examines that knee, reproducing that pain or catching, we will
most commonly order a Magnetic Resonance Image, or MRI, of the knee.
The MRI will show the fibrous shock absorber, the meniscus, and the tear
pattern. Then, upon deciding to treat the meniscus, an outpatient, arthroscopic
procedure can be performed, where a patient goes to an outpatient surgery
center and, under a local or general anesthesia, the surgeon looks inside
the knee with an arthroscope, examining the torn meniscus cartilage and
deciding, at that time, whether to trim away the damaged tissue or repair
it with sutures. The cleaner and fresher the tear or the younger the tissue,
the easier it is to repair and save the meniscus cartilage, which is generally
the best option for the knee joint because saving the meniscus permits
the normal shock absorber to heal and protect the knee joint over time.
However, if it is a degenerative, torn, shattered meniscus, trimming the
meniscus is a more common procedure. How the surgeon trims the meniscus
and how much meniscus is lost will often determine the outcome of the surgery
and the long-term results for the knee. If the meniscus can be shaved carefully
and artfully back into a shape very similar to its normal shape, then the
knee joint will, most likely, not miss the missing meniscus cartilage.
That’s where arthroscopic surgery is both a science, determining
what to do to treat the meniscus, and an art, how good is the surgeon at
shaping and trimming that meniscus, how important does he perceive it to
be, and how easy it is to perform in that individual patient’s knee.
The meniscus is torn about one million times per year in the United States,
leading to out-patient arthroscopic surgeries about 1.4 million times just
for that one torn meniscus cartilage tissue. It is an extremely common
event and, most of the time, patient’s do very well. Unfortunately,
sometimes, if the meniscus cartilage is significantly damaged and a lot
of it needs to be removed, the patient will suffer pain and eventually
arthritis, the wearing away of the cartilage in the joint. Then, the patient
asks the surgeon, “Isn’t there something else you can put back
into the knee joint to cushion the bones and replace the meniscus?” Today,
we most commonly do that with a meniscus allograft, a donor meniscus cartilage
that we take from a cadaver and insert back into the knee, sew into place,
and thus provide a new shock absorber for that knee joint, replacing the
missing meniscus. Traditionally, it was thought that you could not replace
the meniscus if the knee had already become arthritic. However, here at
The Stone Clinic over the last ten years, we have been conducting a study
of the survival of meniscus cartilage in arthritic joints and have demonstrated
in the first part of the study, a two to seven year follow-up, that the
meniscus can survive in an arthritic joint, if it is sewn in carefully,
a host of specific rehabilitation programs are followed, and the opposing
arthritic surfaces are treated, very commonly with a grafting procedure
called a paste graft, which helps restore that articular cartilage. We
will have another conversation about paste grafting at a later lecture.
For today however, the focus is on the meniscus cartilage, how it is injured,
how it is saved, what the biology is, and what the replacement options
are for the future. It should be noted that soon in the future there will
be replacement options for replacing portions of the meniscus and that
is called a collagen meniscus implant, which was also invented here, at
The Stone Clinic, and first tested in early 1991. It is now for sale in
Europe, Chile, and Australia and is finishing clinical trials here in the
United States. It will most likely end up being a partial replacement for
the meniscus cartilage. I hope this has been helpful and I look forward
to answering any questions that someone might have.
Q: Dr. Stone, when athletes routinely pound the meniscus through running,
cycling, or other sports, it will deteriorate over time. After how long
or at what age would they anticipate the meniscus will be so deteriorated
that it will no longer function successfully?
Actually, it turns out that, in a normal knee joint, one that has not
been injured, the meniscus cartilage and the articular cartilage do not
normally degenerate and do not develop arthritis, unless, there is a genetic
predisposition to arthritis or there is some other cause.
In an injured knee joint, where rough surfaces are present or where the
meniscus has been injured by an impact lesion, then the meniscus goes on
to either degenerative tear or frank tear that causes injury and subsequent
pain or arthritis. But a normal knee can take running forever, as long
as there are good genes involved.
Q: Dr. Stone, are there any tests available to tell how well or how poorly
my meniscus is doing?
An orthopaedic surgeon can examine your knee and tell whether or not there
are rough areas, catching, or popping inside the joint. An MRI can be performed,
which studies the structure of the cartilage, the surfaces, and all the
other tissues around the joint. It can give a very accurate indication
of the health of the tissue, as long as it is a high quality MRI, focused
on knee joint specific anatomy. An x-ray, a plain x-ray, can give an indication
of the health of the joint by looking at the joint space present between
the bones but it does not specifically look at the meniscus cartilage itself.
Q: Dr. Stone, a friend of mine has had his meniscus removed years ago.
Is he a candidate for the meniscus allograft that you talked about, the
cadaveric transplantation?
Possibly, when people have lost their meniscus and they develop knee pain
at the site of the meniscus cartilage, then those are the most common patients
who seek us out, here at the clinic in San Francisco for meniscus cartilage
transplantation. The common story is that they were playing football in
college, injured their knee, a surgeon removed the meniscus, they went
on to play for another 10 or 15 years, and now they have joint pain at
that site. That’s the most common person presenting for a meniscus
replacement surgery in our practice. The other people who present are the
young person, who unfortunately tears it and the surgeon had to remove
the meniscus cartilage or the older person who is looking for shock absorption,
in order to delay the time for joint arthroplasty or joint replacement.
Q: Dr. Stone, my mother has been told that she is a candidate for joint
replacement. Is there any way that this meniscus allograft can keep her
from having that operation?
Meniscus replacement can be done in older people with arthritis, as a
way to buy time or delay the time at which an artificial joint might be
placed in the knee. This clearly depends on the patient, how much arthritis
there is in the knee, and whether or not the patient is able to participate
in a careful rehab and exercise program. But we have been pleasantly surprised
by some of our patients who have pushed us hard and said, “Listen,
Doc, I’m not going to let you put an artificial knee in, not yet
anyhow. I still want to run, or play volleyball, or play tennis, and be
really active. I’d like you to put something biologic in there and,
even if it only lasts me five years, that is good enough because I want
to keep playing sports.” Those are our patients in their 50s, 60s,
and even our 70-year-olds who have pushed us and said, “Look, I want
some more athletic time and I would like you to try that.” And we
have been pleasantly surprised to see that replacing the shock absorber
in the knee, even in some really, significantly arthritic knees has provided
those patients with pain relief, shock absorption, and additional years
of good use of their knee joint. It doesn’t apply to everyone and
we have careful criteria we use when examining the patient, doing our own
office MRIs, and working with our physical therapy team to determine which
patients would be ideal for this procedure. But we are willing to try it
for people who are the right candidates. |
