Torn Meniscus

What Is It?

A meniscus is a disk-shaped piece of cartilage that acts as a shock absorber inside a joint. Each knee has one lateral meniscus under the outer knob of the thighbone and one medial meniscus under the inner knob of the thighbone. Each meniscus acts as a natural cushion between the thighbone (femur) and shinbone (tibia). The two cushions prevent excess wear and tear inside the knee joint by keeping the ends of the two bones from rubbing together. Each meniscus also absorbs much of the shock of jumps and landings, and helps to distribute joint fluid evenly to lubricate and nourish the knee.

In the United States, a torn meniscus is the most common reason for knee surgery. In 1996 alone, treatment for a torn meniscus accounted for more than 250,000 clinic visits to U.S. medical centers.

Symptoms

The symptoms of a torn meniscus can include:

• Knee pain, usually on one side of your knee
• Tenderness at the side of the joint
• Knee swelling within the first 12 hours after injury
• A "locked" knee that can't be bent
• A knee that catches during movement, or can't be fully straightened
• A click, pop or grinding inside your knee when you move it
• A knee that buckles, gives way or feels generally weak

Diagnosis

Your doctor will inspect both your knees to compare your injured knee with your uninjured one. He or she will check your injured knee for signs of swelling, tenderness and fluid inside the knee joint. If your knee is not locked, the doctor will bend your injured knee and check for clicks, snaps and "catches" within the joint. Your doctor also will also evaluate your knee's range of motion and will maneuver your knee to see whether your meniscus is sensitive to pressure. For example, in the "McMurray test," the doctor bends the leg at the knee, and then rotates it inward or outward while straightening it. If you feel pain during this test or there is a "click" sound as your leg rotates, there is a good chance that your meniscus is torn.

If the results of your exam suggest you have a torn meniscus, you may need tests to further evaluate your knee. Tests may include:

• Knee X-rays to check for bone injuries, including fracture, that can cause symptoms similar to a torn meniscus
• A magnetic resonance imaging (MRI) scan or computed tomography (CT) scan — Nine out of 10 times, a torn meniscus will show up on one of these tests.
• Arthroscopy (camera-guided surgery) to look inside the knee joint and examine the meniscus — When arthroscopy is used for diagnosis, the problem can be treated during the same surgery.