Baker's cyst

A Baker's 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 Baker's cyst, also called a popliteal (pop-LIT-e-ul) 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 Causes Complications

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

  • Swelling behind your knee, and sometimes in your leg
  • Knee pain
  • Stiffness

Your symptoms may be worse after you've been active, or even if you've just been standing for a long time.

When to see a doctor

If you're experiencing pain and swelling behind your knee, see your doctor to determine the cause. Though unlikely, a bulge behind your knee may be a sign of a more serious condition rather than a fluid-filled cyst.

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