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Baker's Cyst


What is a Baker's cyst?

A Baker's cyst, or popliteal cyst, is a bulging lump behind your knee. Inside the lump is a sac filled with fluid.

What causes a Baker's cyst?

A Baker's cyst is caused by an abnormal buildup of joint fluid in your knee. This can happen if you have a knee injury, such as a cartilage tear. Osteoarthritis or rheumatoid arthritis can also cause an abnormal buildup of joint fluid.

What are the signs and symptoms of a Baker's cyst?

  • You may have a lump or swelling in the back of your knee when you stand or walk. The swelling may go away when you bend your knee.
  • You may have knee pain.
  • You may have stiffness or tightness in your knee. This may get worse with movement.

How is a Baker's cyst diagnosed?

  • Transillumination: Your caregiver will shine a light through your cyst. This test can show that the cyst is filled with fluid.
  • Joint x-ray: This is a picture of the bones and tissues in your knee joint. This test will show other problems, such as arthritis.
  • Ultrasound: An ultrasound is a simple test used to look inside your body. Sound waves are used to show pictures of your knee on a TV-like screen.
  • MRI: This scan uses powerful magnets and a computer to take pictures of your knee. It is used to look for fluid buildup or a knee injury. You may be given dye to help the pictures show up better. Tell the caregiver if you have ever had an allergic reaction to contrast dye. Do not enter the MRI room with anything metal. Metal can cause serious injury. Tell the caregiver if you have any metal in or on your body.

How is a Baker's cyst treated?

A Baker's cyst will usually go away on its own. If it is large and painful, you may need any of the following:

  • Medicines:
    • NSAIDs: NSAIDs may be given to decrease swelling and pain. This medicine can be bought without a doctor's order. NSAIDs can cause stomach bleeding or kidney problems if they are not taken correctly.
    • Steroid medicine: This is injected into the cyst to decrease fluid, redness, pain, and swelling.
  • Aspiration: Your caregiver will use a needle to drain the fluid from the cyst.
  • Arthroscopic surgery: This is done to remove the cyst completely or repair any torn or damaged cartilage. A scope and small surgical instruments are inserted through a small incision in your knee. A scope is a flexible tube with a light, camera, and magnifying glass on the end.

How can I care for my knee when I have a Baker's cyst?

  • Rest: Limit movement as your knee heals. This will help decrease the risk of more damage to your knee. You may need crutches to take weight off your injured knee. Use crutches as directed.
  • Ice: Ice your knee to help decrease swelling and pain. Use an ice pack or put ice in a plastic bag. Cover the ice pack with a towel and place the ice on your knee for 15 to 20 minutes, 3 to 4 times each day. Do this for 2 to 3 days.
  • Support: Support your knee by wrapping it with an elastic bandage. Ask your caregiver if you need a brace for more support. This will help decrease swelling and movement so your knee can heal.
  • Elevate: Use pillows to raise your knee above the level of your heart as often as you can. This will help decrease swelling.

What are the risks of a Baker's cyst?

Baker's cysts commonly return, even after aspiration. If you have surgery, you could get an infection or bleed too much. Without treatment, the cyst will continue to grow and it could burst inside your knee. If this happens, the joint fluid can leak into your calf and cause redness, swelling, and pain in your calf.

When should I contact my caregiver?

Contact your caregiver if:

  • You have a fever.
  • Your pain does not improve with medicine.
  • You have questions or concerns about your condition or care.

When should I seek immediate care?

Seek care immediately or call 911 if:

  • You have severe pain.
  • You have bruising on the ankle below the cyst.
  • Your calf turns blue below the cyst.
  • You have swelling or bleeding on the leg with the cyst.

Care Agreement

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. 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.

© 2015 Truven Health Analytics Inc. Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes. All illustrations and images included in CareNotes® are the copyrighted property of A.D.A.M., Inc. or Truven Health Analytics.