Patient education: Baker's (popliteal) cyst (The Basics)

What is a Baker's cyst? — A Baker's cyst is a fluid-filled sac behind the knee (figure 1). This cyst can cause symptoms, such as knee pain or stiffness. The medical term for a Baker's cyst is "popliteal cyst."

What are the symptoms of a Baker's cyst? — Baker's cysts do not always cause symptoms. When they do, the symptoms can include:

●Pain in the back of the knee

●Knee stiffness

●Swelling or a bulge at the back of the knee, especially when the leg is straight

People often find that their symptoms get worse if they stand for a long time or bend their knee too far. Symptoms and swelling sometimes also get worse with activity.

In some cases, Baker's cysts tear open and leak their fluid onto nearby tissues. If that happens, symptoms can include calf swelling and redness, or bruising below the knee.

Should I see a doctor or nurse? — Yes, if you have the symptoms described above, see your doctor or nurse. Not all swelling behind the knee is due to a Baker's cyst. Your doctor or nurse can look at your knee and talk to you about your symptoms to decide what to do next.

Will I need tests? — Probably not. If you have a Baker's cyst, your doctor or nurse will probably be able to tell just by doing an exam. But if they are not sure, you might need an imaging test, such as an X-ray or an ultrasound. Imaging tests create pictures of the inside of the body

How is a Baker's cyst treated? — The main treatment is an injection of steroid medicines directly into the knee. These medicines reduce swelling and inflammation.

If treatment with steroid medicines does not work, there are other options. But these are much less used. They include:

●Draining the cyst with a needle

●Surgery to remove the cyst

Is there anything I can do on my own to feel better? — Maybe. Your doctor or nurse might suggest resting the knee and taking medicines called "NSAIDs" for 1 to 2 weeks before they order an imaging test or suggest a knee injection. Some examples of NSAIDs include ibuprofen (sample band names: Advil, Motrin) and naproxen (sample band names: Aleve).

More on this topic

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Patient education: Knee sprain (The Basics)
Patient education: Knee arthroscopy (The Basics)

Patient education: Knee pain (Beyond the Basics)