Quick Facts: Baker Cyst - Merck Manuals Consumer Version

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What are the symptoms of a Baker cyst?

How can doctors tell if I have a Baker cyst?

How do doctors treat a Baker cyst?

Muscle, Bursa, and Tendon Disorders

Polymositis is characterized by inflammation and degeneration of the muscles. Dermatomyositis is polymositis accompanied by skin inflammation. In which of the following age groups do these disorders typically occur?

Adults ages 40 to 60 years, and children ages 5 to 15 years
Children of all ages, and young adults ages 20 to 29 years
Infants and young children ages 2 to 10 years
Young children ages 2 to 10 years, and adolescents ages 12 to 19 years

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The Manual's Editorial Staff

Last full review/revision Jul 2020| Content last modified Jul 2020

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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

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:

Rheumatoid arthritis
Osteoarthritis
Torn cartilage in the knee

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

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.

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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Systemic Sclerosis

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Bursitis

Baker Cysts

Rheumatoid Arthritis (RA)

Introduction to Muscle, Bursa, and Tendon Disorders

Autoimmune Disorders

Bones

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What is a Baker cyst?