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The medial meniscus and lateral meniscus are
specialized structures within the knee. These
crescent-shaped shock absorbers between the tibia and femur
have an important role in the function and health of the
knee. Once thought to be of little use, the menisci (plural)
were routinely removed when torn. Now we know that the
menisci contribute to a healthy knee because they play
important roles in joint stability, force transmission and
lubrication. When possible, they are repaired if injured.
There are two categories of menlscal Injuries; acute
tears and degenerative tears.
• An acute tear
usually occurs when the knee is bent and forcefully twisted,
while the leg is in a weight bearing position. Statistics
show that about 61 of 100,000 people experience an acute
tear of the meniscus
• Degenerative tears
of the meniscus are more common in older people. Sixty
percent of the population over the age of 65 probably has
some sort of degenerative tear of the meniscus. As the
meniscus ages, it weakens and becomes less elastic.
Degenerative tears may result from minor events and there
may or may not be any symptoms present.
What are the menisci?
The two menisci of the knee are crescent-shaped
wedges that fill the gap between the tibia and femur.
The menisci provide joint stability by creating a cup for
the femur to sit in. The outer edges are fairly thick while
the inner surfaces are thin.
What does the meniscus do?
The meniscus acts as a shock absorber for the knee
by spreading compression forces from the femur over a wider
area on the tibia.
What are the signs and symptoms of a meniscus
injury?
• Acute tears are
often sports related and usually the result of a twisting
injury in the younger, active adult population. Symptoms of
an acute tear are usually pain, swelling, and movement
irregularities. When the tear gets in the way of normal knee
motion, the knee can “catch” or “lock” as it moves.
• Degenerative tears
are more common in the older population. The patient may
experience repeated swelling, but often can't recall any
specific injury. The swelling also may be the result of an
injury caused by a very minor movement. Mechanical
symptoms, such as the knee catching or locking, often exist
or the patient may simply experience pain.
How is a meniscus Injury diagnosed?
The orthopaedic surgeon will first take a history
of the injury to help determine if the signs and symptoms
might suggest Meniscal damage. Next the doctor will evaluate
the knee for swelling and tenderness in a physical
examination. The knee will be tender when pressed on the
injured side where the tibia and femur meet.
The doctor may use imaging to assess the amount of
damage; X-rays can show any fractures or arthritic
conditions in the knee. A narrow joint space or bone
changes indicate bone-on-bone rubbing and arthritis, if the
diagnosis is still not clear, an MRI (Magnetic Resonance
Image) may be ordered to evaluate damage to ligaments and
menisci.
Treatment
When determining the treatment for a Meniscal tear, the
orthopaedic surgeon will consider the following factors:
- The patient’s activity level
- The patient's age
- The location of the tear and the type of tear
- When the Injury happened
- Injury symptoms
- Any other associated injuries
After considering these factors the doctor will choose to
treat the Injury non-operatively or surgically.
Non-operative Treatment
Some tears may have no symptoms and in other tears,
symptoms may eventually disappear. Partial tears,
degenerative tears, and stable tears may be observed for 6-8
weeks. If symptoms disappear, no surgery is needed. The use
of a knee brace and restriction of activities may be
recommended to prevent further injury. Physical Therapy can
be used to decrease inflammation and decrease pain. A
cortisone injection can provide symptomatic relief.
Surgical Treatment
Surgical treatment for a menlscal tear may be indicated
if:
- Symptoms are disabling or last for more than 6-8
weeks
- A displaced tear causes the joint to lock
- The anterior cruciate ligament is also injured. In
this case, the knee is highly unstable and excessive
motion exists within the joint. The meniscus is unlikely
to heal without treatment.
- The patient is a high-level athlete
- Recovery
- Partial Resection/ Partial Meniscectomy
- The rehabilitation program for a partial resection
of the meniscus may include:
- Crutch use for the first 2 - 3 days following
surgery due to postoperative pain and swelling. After
this, the patient may be weightbearing as tolerated.
- Range of motion exercises are emphasized at first.
- Strength exercises begin once swelling has subsided.
- Return to activities can start at about 3-6 weeks
following surgery.
Eric T. Shapiro MD
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