Like a lot of knee injuries, a meniscus tear can be painful and debilitating. Unfortunately, it’s quite common. In fact, a meniscal tear is one of the most frequently occurring cartilage injuries of the knee.

So what is the meniscus? It’s a piece of cartilage in your knee that cushions and stabilizes the joint. It protects the bones from wear and tear. But all it takes is a good twist of the knee to tear the meniscus. In some cases, a piece of the shredded cartilage breaks loose and catches in the knee joint, causing it to lock up.

Meniscus tears are common in contact sports like football as well as non-contact sports requiring jumping and cutting such as volleyball and soccer. They can happen when a person changes direction suddenly while running, and often occur at the same time as other knee injuries, like an anterior cruciate ligament (ACL) injury. Meniscus tears are a special risk for older athletes since the meniscus weakens with age. More than 40% of people 65 or older have them.

Symptoms of a meniscus tear include:

• Pain in the knee
• Swelling
• A popping sensation during the injury
• Difficulty bending and straightening the leg
• A tendency for your knee to get “stuck” or lock up

At first, the pain may not be bad. You might even play through the injury. But once the inflammation sets in, your knee will probably hurt quite a bit.

To diagnose a meniscus tear, your doctor will give you a thorough exam. He or she will want to hear details about how you got your injury. X-rays may be necessary, to rule out broken bones and other problems. You may also need an MRI (Magnetic Resonance Imaging) scan, which allows a more detailed evaluation of knee cartilage.

Treatment for meniscal tears depends on the size and location of the tear. Other factors which influence treatment include age, activity level and related injuries. The outer portion of the meniscus, often referred to as the red zone, has a good blood supply and can sometimes heal on its own if the tear is small. In contrast, the inner two thirds of the meniscus, known as the white zone, does not have a good blood supply. Tears in this region will not heal on their own as this area lacks blood vessels to bring in healing nutrients.