The meniscus is a cartilage inside the knee joint. It has semilunar (sickle)
shape and it's main purpose is to deepen the relatively flat surface of the upper end of
the shin bone. The meniscus distributes the force around the knee joint. Actually the
meniscus bears about 40% of the load transmitted through the knee joint. Also meniscus
adds some stability to the knee joint.
What is the meniscus and what does it do?
The meniscus acts like a gasket between the femur and the tibia to spread out the
weight being forces transferred from the thigh above to the leg below. The ability
of the meniscus to spread out the force on the joint surfaces as one walks is important
because it protects the articular cartilage from excessive wearing. Without the
meniscus, the concentration of force into a small area on the articular cartilage can
damage the surface, leading to degeneration, called osteoarthritis.
Also the meniscus helps with the stability of the knee joint. The meniscus
converts the tibial surface into a shallow socket. A socket is more stable
than a flat surface. Without the meniscus, the round femur would be able to slide on
top of the flat tibial surface.
The meniscus can be torn in several ways. The entire inner rim of the medial
(inner) meniscus can be torn in what is called a bucket handle tear. The meniscus
can also have a flap torn from the inner rim, or the tear can be a degenerative tear where
a portion of the meniscus is frayed and torn in multiple directions.
How does the meniscus cause problems in the knee?
Meniscus injuries can occur in any age group, but the causes are somewhat different for
each age group. In younger people, the meniscus is a fairly tough and rubbery
structure. Tears in the meniscus in patients under the age of thirty usually occur
as a result of a fairly forceful twisting injury. In the younger age group, meniscal
tears are more likely to be caused by a sport activity.
In older people, the meniscus grows weaker with age. The tissue that makes up the
meniscus becomes degenerative and is much easier to tear. Meniscal tears in the
older age group occur as a result of a fairly minor injury, even from the up and down
motion of squatting. Degenerative tears of the meniscus are commonly seen as a part
of the overall condition of osteoarthritis of the knee in the older population. In
many cases, there is no one associated injury to the knee that leads to the meniscal tear.
What does a torn meniscus feel like?
The most common problem caused by a torn meniscus is pain . The pain may be felt along the joint line where
the meniscus is located or may be more vague and involve the whole knee. If the torn
portion of the meniscus is large enough, locking may occur. Locking simply refers to
the inability to completely straighten out the knee. Locking occurs when the fragment
of torn meniscus gets caught in the hinge mechanism of the knee and will not allow the leg
to straighten completely. (Imagine sticking a pencil between the hinges in a door
and trying to close it.)
There are long term effects of a torn meniscus as well. The constant
rubbing of the torn meniscus on the articular cartilage may cause wear and tear on the
surface, leading to degeneration of the joint. The knee may swell with use and
become stiff and tight. This is usually because of fluid accumulating inside the
knee joint - sometimes called water on the knee. This is not unique to
meniscus tears, but occurs whenever the knee becomes inflamed.
How do we look into this problem?
Diagnosis begins with a history and physical. The examination will try to
determine where the pain is located, whether or not locking has occurred, and if you have
any clicks or pops as the knee is moved. X-rays will not show the torn
meniscus. X-rays are mainly useful to determine if other conditions are
present. The MRI scan is very good at showing the meniscus. The MRI
(Magnetic Resonance Imaging) machine uses magnetic waves rather than x-rays, to show the
soft tissues of the body. With this machine, we are able to "slice"
through the area we are interested in very clearly. Usually, this test is done to
look for injuries, such as tears in the menisci or ligaments of the knee. This test
does not require any needles or special dye, and is painless. If there is a
uncertainty in the diagnosis following the history and physical examination, or if other
injuries in addition to the meniscal tear are suspected, the MRI scan may be suggested.
If the history and physical examination strongly suggest that a torn meniscus is
present, then arthroscopy may be suggested to confirm
the diagnosis and treat the problem at the same time. Arthroscopy is a type of an
operation where a small fiberoptic TV camera is placed into the knee joint, allowing the
orthopedic surgeon to look at the structures inside the knee joint directly. The
arthroscope allows your doctor to actually look into the knee joint and see the condition
of the articular cartilage, the ligaments and the menisci .
How do we treat this problem?
d to remove the torn portion of meniscus while the arthroscope is used to see what
Initial treatment for a torn meniscus usually is directed towards reducing the pain and
swelling in the knee. Your physician may recommend crutches for resting the knee for
several days and suggest ice to reduce the pain and swelling. If the knee is locked
and cannot be straightened out, surgery may be recommended as soon as reasonably possible
to remove the torn portion that is caught in the knee joint. Once a meniscus is
torn, it will most likely not heal on its own.
If the symptoms continue, surgery will be required to either remove the torn portion of
the meniscus or to repair the tear. Most meniscus surgery today is done using the
arthroscope. Small incisions are made in the knee to allow the insertion of a small
TV camera into the joint. Through another small incision, special instruments are
In some cases, the meniscus tear can be repaired. The arthroscope is used to view
the torn meniscus. Sutures are then placed into the torn meniscus until the tear is
repaired. Repair of the meniscus is not possible in all cases. Young
people with relatively recent meniscal tears are the most likely candidates for
repair. Degenerative type tears in older people are not usually repairable.
provided here is not meant to take the place of the complete exam by a physician. If you
have an injury we strongly encourage you to get adequate medical care