Baker's Cyst

GENERAL INFORMATION:

What is a Baker's cyst? A Baker's cyst is also called a popliteal cyst. It is an abnormal swelling of a bursa. 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 is when a bursa behind the knee swells up and fills with synovial fluid (joint fluid).

What causes a Baker's cyst? Baker's cyst may caused by any of the following:

• Arthritis of the knee, such as osteoarthritis, or rheumatoid arthritis.
  
  
• Connection of the bursa with the knee joint.
  
  
• Trauma (injury) causing a tear in the meniscus of the knee. The meniscus is found between the knee bones, they protect the joint by acting as a shock-absorber.

What are the signs and symptoms of a Baker's cyst? You may have one or more of the following:

• A swelling in the back of the knee when standing or walking. The swelling disappears when knee is bent.
  
  
• A feeling of fullness or tightness in the area behind the knee.
  
  
• It becomes hard to move the knee, this is often worse by with movement.
  
  
• Pain behind the knee.

How is Baker's cyst diagnosed?

• Transillumination: This is done by shining a light through the cyst. This test can show that the cyst is filled with fluid.
  
  
• Imaging tests:
  
  
  • Arthrogram: An arthrogram is an x-ray of the joint using dye. The dye helps your caregiver better see the joint and the area around the joint.
    
    
  • Computerized axial tomography scan: This is also called a "CAT" 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. This may show other problems that may be present, such as arthritis.
    
    
  • Magnetic resonance imaging: This is also called "MRI". During the MRI, pictures of your knee are taken. An MRI may be used to look for fluid cysts, or other knee abnormalities, such as injury to the meniscus.
    
    
  • Ultrasound: An ultrasound is a simple test that uses sound waves to show pictures of your knee.

How is Baker's cyst treated? Treatment for Baker's cyst will depend on it's size and the symptoms you have. A Baker's cyst that is small or does not cause symptoms is treated with bed rest and rehabilitation of the knee. Medicines, such as cortisone injections, may be given to decrease pain or swelling. Surgery may be done if the cyst is very large or painful. Surgery may be done to remove the cyst and repair a tear of the meniscus. Aspiration (draining off the fluid) with a needle may also help decrease the size of the cyst.

CARE AGREEMENT:

You have the right to help plan your care. To help with this plan, you must learn about your health condition and how it may be treated. You can then discuss treatment options with your caregivers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.

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