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Baker's Cyst


A Baker's cyst is also called a popliteal cyst. It is an abnormal swelling of a bursa behind the knee. A bursa is a fluid-filled sac that is found between tendons and muscles. Bursas decrease friction (rubbing) between tendons, bones, and skin. A Baker's cyst may be caused by arthritis or trauma (injury) of the knee. You may have a bulge in the back of the knee when standing or walking, that disappears when the knee is bent. Symptoms may include pain, swelling, or tightness behind the knee. You may have a test to show that the cyst is filled with fluid. Diagnosis may be made using joint x-ray, computerized tomography (CAT) scan, magnetic resonance imaging (MRI), or ultrasound. Treatment for Baker's cyst will depend on it's size and the symptoms you have. A Baker’s cyst that is small and does not cause problems is treated with bed rest and rehabilitation or "rehab" of the knee. Large or painful cysts may need surgery.


You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment.


Treatment of Baker’s cyst may cause unpleasant side effects. You could get an infection or bleed too much with surgery. Most of the time, Baker’s cyst come back after aspiration (draining off the fluid) with a needle. If left untreated, it may continue to grow or burst. Baker’s cyst usually does not cause any harm over time if treated early. Ask your caregiver if you are worried or have questions about your disease, medicine, or care.


Informed consent:

A consent form is a legal document that explains the tests, treatments, or procedures that you may need. Informed consent means you understand what will be done and can make decisions about what you want. You give your permission when you sign the consent form. You can have someone sign this form for you if you are not able to sign it. You have the right to understand your medical care in words you know. Before you sign the consent form, understand the risks and benefits of what will be done. Make sure all your questions are answered.

Blood tests:

You may need blood taken to give caregivers information about how your body is working. The blood may be taken from your hand, arm, or IV.


Steroid medicine Steroids may be injected into the cyst to decrease the amount of fluid, redness, pain, and swelling. This does not usually stop the cyst from coming back.


  • Computerized axial tomography scan: A special x-ray machine uses a computer to take pictures of your knee. You may be given dye before the pictures are taken. The dye is usually given in your IV. The dye may help your caregiver see the pictures better. People who are allergic to iodine or shellfish (lobster, crab, or shrimp) may be allergic to some dyes. Tell the caregiver if you are allergic to shellfish, or have other allergies or medical conditions.
  • Joint x-ray: This is a picture of the bones and tissues in your joints. Joints are the places in your body where two bones meet. You may be given dye as a shot into your joint before the x-ray. This dye will help your joint show up better on the x-ray. A joint x-ray with dye is called an arthrogram.
  • Magnetic imaging resonance: During the MRI, pictures of your knee are taken. An MRI may be used to look for fluid in the cyst, or other knee problems, such as injury to the meniscus. You will need to lie still during an MRI. Never enter the MRI room with an oxygen tank, watch, or any other metal objects. This can cause serious injury. Tell your caregiver if you have any metal implants in your body.
  • Ultrasound: An ultrasound is a simple test that uses sound waves to show pictures of your knee on a TV-like screen.

Treatment option:

Arthroscopic surgery: You may have surgery to remove the cyst and repair a tear of the meniscus. This surgery uses a scope to look inside your knee. The scope is a long tube with magnifying glass, camera and light on the end. During surgery, the scope is inserted through a small incision in your knee. Your caregiver may also put surgical instruments through other small incisions to remove or repair damaged tissues. The incision is closed with stitches or staples.

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Learn more about Baker's Cyst (Inpatient Care)

Micromedex® Care Notes