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Medically speaking, the
"cartilage" is actually known as a meniscus. The
meniscus is a C-shaped piece of fibrocartilage, which is
located at the peripheral aspect of the joint. There are
two meniscii in each knee, the medial meniscus, and the
lateral meniscus. The majority of the meniscus has no
blood supply. For that reason, when damaged, the
meniscus is usually unable to undergo the normal healing
process that occurs in most of rest of the body. In
addition, with age, the meniscus begins to deteriorate,
often developing degenerative tears. Typically, when the
meniscus is damaged, the torn piece begins to move in an
abnormal fashion inside the joint. Because the space
between the bones of the joint is very small, as the
abnormally mobile piece of meniscal tissue moves, it may
become caught between the bones of the joint (femur and
tibia). When this happens, the knee becomes painful,
swollen, and difficult to move.
Usually this situation
requires that the torn piece be removed. However,
sometimes, the meniscus tear is along the peripheral
(outer) aspect of the tissue. |
Figure 1:
Frontal View of Right
Knee
with Patella Tendon
Removed |
DIAGNOSIS AND TREATMENT
When a physician is
evaluating an injured knee, a history is taken to
determine the specific problems that a patient is having
with the knee. Next a physical examination of the area
will be performed to determine the site of the pain, the
presence or absence of physical findings that are known
to be associated with a torn meniscus, and x-rays are
performed to identify other abnormalities that may give
similar problems to those of a torn meniscus. In some
instances, additional diagnostic tests such as an MRI
may be ordered. If the history and physical findings
indicate that a tear is present, arthroscopic surgery
may be indicated for treatment. Although MRI scans are
valuable in detecting meniscal tears, the peripheral
menisco-capsular tear is the most difficult to detect.
Often this pattern of tear is only detected at the time
of the arthroscopic examination.
To examine the injured
joint, it is necessary to insert a small fiber optic
telescope (arthroscope) into the joint. Typically, this
is done with miniature instruments that are inserted
through incisions that are approximately 1/8 inch long.
The procedure is performed as an outpatient. After
examining the damaged meniscus through the arthroscope,
the surgeon must then decide if the tear is repairable,
or should be removed.
Prior to attempting a
meniscal repair, the operating surgeon and the patient
need to take into consideration a number of variables.
Only by recognizing these variables and their impact on
the probability of the success of the procedure, can the
surgeon and patient make an honest assessment of the
nature of the injury and the best procedure, removal or
repair. Among the factors that must be considered by the
surgeon are the patient's age, health, lifestyle,
physical demands of the patients, the ability of the
patient to undergo a major reconstructive procedure, the
location of the tear, the type of the tear, associated
intra-articular pathology, the width of the remaining
uninjured tissue, the length of the tear, the presence
or absence of ligamentous instability, and the patient's
ability to remain on crutches and activity restrictions
for a significant period of time. Because of all of the
factors that must be considered, coupled with the poor
blood supply of the meniscus, the majority of tears are
not suitable for repair.
The age of the patient
becomes significant because as the patient gets older,
the likelihood of a degenerative tear increases and the
probability of a repairable tear significantly
decreases. Also, with increasing age, the quality of the
meniscal tissue deteriorates, thereby decreasing the
success rate of meniscal repairs.
Although the meniscal
repair is performed arthroscopically as an outpatient,
the recovery is longer because the incisions are often
larger then the standard incisions used for arthroscopic
removal of a torn meniscus. Since healing must occur,
the physical therapy must be slower and more cautious,
most patients remain on crutches for several weeks, and
complete healing may take several months. |
