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Baker's cyst

A Baker's cyst is a swelling behind the knee. It is a collection of fluid, where normal joint fluid leaks to the back of the knee and creates a swelling. 

It commonly occurs due to degenerative changes in the knee. It may or may not cause pain and discomfort at the back of the knee and calf.

Why does a Baker's cyst occur?

This is to do with degenerative changes of the tissues at the back of the knee. The knee normally has fluid in the joint, known as synovial fluid. When there is degeneration, this fluid then leaks out of the joint into a collection at the back of the knee. The fluid cant come back into the knee because of a one-way valve mechanism, and thus causes a swelling.


What are the symptoms of a Baker's cyst?

A Baker's cyst may cause:

- Discomfort at the back of the knee with prolonged walking or running

- A swelling that you can feel or see

- Discomfort after sitting in the same position for long

- Calf pain if the cyst bursts or leaks fluid down into the calf muscles

It may also not cause any pain or discomfort at all.

How do I know if I really have a Baker's cyst?

A physical examination by an Orthopaedic specialist followed by a confirmatory MRI scan would be able to diagnose a Baker's cyst. 

What are some simple ways to treat a Baker's cyst?


A compressive knee guard may help to reduce discomfort during activity. However, this helps with only the symptom but the cyst is still there.

Aspiration of the cyst (using a needle to insert into the cyst and suck out the fluid) temporarily removes the fluid, but it is very likely to re-accumulate again.

What, then, is the proper treatment for a Baker's cyst?

As this is a structural, physical collection of fluid, the proper treatment is removal of the cyst and the one-way valve mechanism. This surgery is nowadays done as a Key-Hole type surgery, using only small cuts in the skin. Long thin instruments are then used to remove the cyst, the wall of the cyst, and the valve mechanism, ensuring the cyst does not re-accumulate again.


The treatment is done with the patient asleep, and patients can be discharged from hospital on the same day or the next day. Patients can walk straight away after the treatment.

What is the recovery for an Arthroscopic (Key-Hole) removal of a Baker's cyst?

Patients can walk straight away with small amounts of pain. They can return to running/cycling/swimming about one month after the treatment. 

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