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.
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.
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 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
- 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