A torn meniscus is one of the most common knee injuries. Any activity that causes you to forcefully twist or rotate your knee, especially when putting the pressure of your full weight on it, can lead to a torn meniscus.

Each of your knees has two menisci — C-shaped pieces of cartilage that act like a cushion between your shinbone and your thighbone. A torn meniscus causes pain, swelling and stiffness. You also might have trouble extending your knee fully.

Conservative treatment — such as rest, ice and medication — is sometimes enough to relieve the pain of a torn meniscus and give the injury time to heal on its own. In other cases, however, a torn meniscus requires surgical repair.

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If you've torn your meniscus, you may experience the following signs and symptoms in your knee:

• A popping sensation
• Swelling or stiffness
• Pain, especially when twisting or rotating your knee
• Difficulty straightening your knee fully
• Experiencing what feels like a block to moving your knee, as if your knee were locked in place

When to see a doctor

Contact your doctor if your knee is painful or swollen, or if you can't move your knee in the usual ways.

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A torn meniscus can result from any activity that causes you to forcefully twist or rotate your knee, such as aggressive pivoting or sudden stops and turns. Even kneeling, deep squatting or lifting something heavy can sometimes lead to a torn meniscus. In older adults, degenerative changes of the knee may contribute to a torn meniscus.

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Often, a torn meniscus can be identified during a physical exam. Your doctor may manipulate your knee and leg bones into different positions to help pinpoint the cause of your signs and symptoms.

Imaging tests

• X-rays. Because a torn meniscus is made of cartilage, it won't show up on X-rays. But X-rays can help rule out other problems with the knee that may have similar symptoms.
• Ultrasound. Ultrasound can allow the doctor to examine the inside of your knee in motion. This can help determine if you have a loose flap of cartilage getting caught between the moving parts in your knee.
• Magnetic resonance imaging (MRI). MRI uses radio waves and a strong magnetic field to produce cross-sectional images of internal structures. It can create detailed images of both hard and soft tissues within your knee.

Arthroscopy

In some cases, your doctor may use an instrument known as an arthroscope to examine the inside of your knee. The arthroscope is inserted through a tiny incision near your knee. The device contains a light and a small camera, which transmits an enlarged image of the inside of your knee onto a monitor. If necessary, surgical instruments can be inserted through the arthroscope or through additional small incisions in your knee.

Source: http://www.mayoclinic.com

A torn meniscus can lead to knee instability, inability to move your knee normally or persistent knee pain. You also may be more likely to develop osteoarthritis in the injured knee.

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Avoid activities that aggravate your knee pain — especially sports that involve pivoting or twisting your knee — until the pain disappears. Ice and over-the-counter pain relievers also can be helpful.

Source: http://www.mayoclinic.com

Anyone performing activities involving aggressive twisting and pivoting of the knee is at risk of a torn meniscus. The risk is particularly high for athletes — especially those who participate in contact sports, such as football, or activities that involve pivoting, such as tennis or basketball. The risk of a torn meniscus also increases as you get older, due to years of wear and tear on your knees.

Source: http://www.mayoclinic.com