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A 19th Century surgeon named William Morrant Baker was the first to describe the condition in which a fluid filled sac developed on the back of the knee. This protrusion, also know as a popliteal cyst, is an accumulation of synovial fluid. The Baker’s cyst can form in the hollow of the knee when the inflammation of arthritis attacks the joint or when the joint is injured. The bulge that forms can range in size and may or may not present with symptoms.

Causes and Symptoms

Like other joints in the body, the knee joint is bathed in synovial fluid. This fluid lubricates the joint so it can move freely. It also reduces friction. A tear in the cartilage of the joint can cause an over-production of synovial fluid. Inflammation from arthritis can also cause this to happen. The excess fluid builds up, creating the Baker’s cyst.

The cyst may form and if it is small, it may not produce any symptoms. A large cyst, however, can be problematic. Pain and swelling may occur when the cyst is big. It may also cause joint stiffness. Some larger cysts limit the range of motion for the knee joint.


A lump in the hollow of the knee can be symptomatic of a few conditions. Therefore, you should always seek medical attention if you notice a problem. Your doctor will examine the protrusion and may use diagnostic imaging to rule out other conditions such as a blood clot, aneurysm or tumor before making the diagnosis of a Baker’s cyst.

Imaging using X-rays, sonogram or ultrasound or MRI will show the condition of the inner structures of the knee. These images can be used to rule out other causes of the lump. After an accurate diagnosis is made, an effective treatment plan can be suggested.


The Baker’s cyst may disappear on its own. This often happens when the underlying cause is treated. If it is caused by arthritis, treating the inflammation can help. If the cartilage in the joint is torn, surgery may be required to repair it and the swollen tissue causing the cyst can be removed at the same time. In some instances, the fluid from the cyst may need to be aspirated.

Additional treatment is often required for large cysts. This can include aspiration, physical therapy or a corticosteroid injection. Treatment reduces pain and inflammation. Your doctor may also recommend the R.I.C.E. protocol.

  • Rest and reduce physical activity
  • Ice the cyst to reduce swelling
  • Compress the area with a compression wrap or sleeve or use a knee brace
  • Elevate the leg

Over-the-counter pain relievers are also advised if the cyst is causing pain. Your doctor will advise you of the best remedy for your cyst after thorough examination and assessment of test results.

A Baker’s cyst is not usually a major problem, although it can slow down your activity. Dr. Glashow provides personalized patient-centered care for Baker’s cyst and other conditions. Call today and schedule your consultation appointment.

Posted on behalf of Jonathan Glashow, MD

737 Park Ave, #1A
New York, NY 10021

Phone: (212) 794-5096


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