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Quick Facts

Baker Cyst

(Baker's Cyst)


The Manual's Editorial Staff

Last full review/revision Jul 2020| Content last modified Jul 2020
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What is a Baker cyst?

A Baker cyst is a fluid-filled sac behind your knee.

  • The fluid in the cyst comes from your knee joint

  • You may not have any symptoms unless the cyst breaks open (ruptures)

  • A ruptured cyst makes your calf swell and hurt

  • Doctors will drain the fluid from the cyst using a needle and then inject corticosteroids

  • Rarely, you'll need surgery for the cyst

What causes a Baker cyst?

Baker cysts can happen when too much fluid builds up in your knee joint. The fluid bulges out at the back of your knee.

Baker cysts are more likely if you have:

What are the symptoms of a Baker cyst?

You may not have any symptoms. If you do, you may have:

  • A bulge at the back of the knee

  • Pain or discomfort at the back of your knee

  • Trouble bending your knee

If the cyst bursts open, the fluid can run down inside your calf and you may have:

  • Painful swelling in your calf

How can doctors tell if I have a Baker cyst?

Your doctor sometimes diagnoses a Baker cyst by examining your knee. Sometimes, doctors do imaging tests, such as:

If the Baker cyst has burst and caused calf swelling, doctors do ultrasound and other tests to check to see if you have a blood clot in the veins in your leg.

How do doctors treat a Baker cyst?

Small Baker cysts don't need treatment and sometimes go away on their own. Doctors will treat any knee problem that is causing the Baker cyst. If the cyst is bigger and bothers you, doctors may:

  • Drain fluid from the cyst with a needle

  • Inject medicine (corticosteroid) into the knee to lessen inflammation

  • Give you medicine for pain

  • Have you do physical therapy to keep the muscles around the knee strong

Rarely, doctors do surgery to remove the cyst.

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