A Bakers cyst is a fluid-filled cyst that causes a bulge and a feeling of tightness behind your knee. The pain can get worse when you fully flex or extend your knee or when you're active.

A Bakers cyst, also called a popliteal cyst, is usually the result of a problem with your knee joint, such as arthritis or a cartilage tear. Both conditions can cause your knee to produce too much fluid, which can lead to a Baker's cyst.

Although a Baker's cyst may cause swelling and make you uncomfortable, treating the probable underlying problem usually provides relief.

Symptoms

In some cases, a Bakers cyst causes no pain, and you may not even notice it. If you do experience signs and symptoms, you may notice:

1) Swelling behind your knee, and sometimes in your leg
2) Knee pain
3) Stiffness
4) Texture similar to a balloon filled with water

Causes

Synovial fluid circulates throughout your knee and passes in and out of various tissue pouches (bursae) throughout your knee. A valve-like system exists between your knee joint and the bursa on the back of your knee (popliteal bursa). This regulates the amount of synovial fluid going in and out of the bursa.

But sometimes the knee produces too much synovial fluid, resulting in buildup of fluid in the bursa and what is called a Bakers cyst. This can be caused by:

1) Inflammation of the knee joint, such as occurs with various types of arthritis
2) Knee injury, such as a cartilage tear

Western medicine Treatments

Many times, no treatment is required and a Baker's cyst will disappear on its own.

If the cyst is very large and causes a lot of pain, the doctor may use the following treatments:

1) Physical therapy. Icing, a compression wrap and crutches may help reduce pain and swelling. Gentle range-of -motion and strengthening exercises for the muscles around your knee also may help to reduce your symptoms and preserve knee function.
2) Fluid drainage. Your doctor may drain the fluid from the knee joint using a needle. This is called needle aspiration and is often performed under ultrasound guidance.
3) Medication. The doctor may inject a corticosteroid medication, such as cortisone, into your knee to reduce inflammation. This may relieve pain, but it doesn't always prevent recurrence of the cyst.

Typically though, doctors treat the underlying cause rather than the Bakers cyst itself.

If the doctor determines that a cartilage tear is causing the overproduction of synovial fluid, he or she may recommend surgery to remove or repair the torn cartilage.

In some instances, particularly if you have osteoarthritis, the cyst may not go away even after your doctor treats the underlying cause. If the cyst doesn't get better, causes pain and interferes with your ability to bend your knee, or if — in spite of aspirations, fluid in the cyst recurs and hinders knee function, you may need to be evaluated for surgery to remove the cyst.

Adopted from Wei Laboratories, Inc.