Baker's Cyst: Symptoms, Causes and What Helps
A soft swelling at the back of the knee, a feeling of tightness when you bend it and sometimes an ache that gets worse after a long day on your feet are typical signs of a Baker's cyst. The name sounds alarming, but in most cases it is not dangerous. This article explains what a Baker's cyst is, why it develops, when a doctor should look at it and what can make everyday life easier.
What is a Baker's cyst?
The knee joint contains a small amount of fluid that helps it move smoothly. When the knee is irritated, it can produce more fluid than usual. Some of this fluid can collect in a small pouch of the joint capsule at the back of the knee, which fills up and bulges out like a little balloon. This pouch is called a Baker's cyst, or a popliteal cyst, after the hollow behind the knee. It is not a tumor, and it is usually a sign that something else in the knee is irritated.
Typical symptoms
- a soft, rounded swelling at the back of the knee, often easier to see when you stand,
- a feeling of tightness or pressure behind the knee, especially when you bend or fully straighten it,
- stiffness after sitting or after a lot of activity,
- an ache that is stronger at the end of the day and eases with rest,
- in some people no symptoms at all, so the cyst is found by chance during an examination.
Why does it develop?
A Baker's cyst rarely appears on its own. It is usually a reaction to another problem inside the knee that leads to extra fluid. Common background causes include:
- knee osteoarthritis and cartilage wear,
- a meniscus tear or another injury inside the knee,
- inflammatory joint diseases such as rheumatoid arthritis,
- gout or other forms of joint irritation.
That is why a doctor will usually look not only at the cyst, but at the whole knee. When the underlying problem calms down, the cyst often becomes smaller too. You can read more about other causes in our article on pain behind the knee.
When should you see a doctor?
Any new swelling behind the knee should be checked by a doctor, because not every lump in this area is a cyst. See a doctor soon if:
- the swelling is growing or is very painful,
- you cannot bend or straighten the knee properly,
- the knee is hot or red, or you have a fever,
- the pain started after an injury.
Seek medical help urgently if your calf suddenly becomes swollen, red, warm and painful. A cyst can sometimes burst and leak fluid into the calf, but the same signs can also point to a blood clot in the leg. Only a doctor can tell the difference, often with an ultrasound scan.
What can help day to day
Treatment depends on the cause and is decided by your doctor. In everyday life, these simple steps help many people:
- for a while, cut back on activities that clearly make the swelling and pain worse, without stopping moving altogether,
- if the knee feels warm and swollen, use a cold pack wrapped in a cloth for 10 to 15 minutes,
- at the end of the day, rest with your leg slightly raised,
- keep the knee moving gently, for example with short walks and easy bending and straightening,
- strengthen the thigh muscles with exercises your physiotherapist recommends.
More practical tips can be found in our article on swollen knee causes and what to do.
Can a knee sleeve help?
A knee sleeve does not make a Baker's cyst disappear and does not treat its cause. Gentle, even compression can, however, give the knee a feeling of support and warmth and make everyday movement more comfortable. Many people find it pleasant on walks or during a long day on their feet. The sleeve should never press hard into the hollow behind the knee. If it pinches, causes pain or the swelling seems bigger, take it off and ask your doctor. If you are unsure, talk to your doctor before you start wearing compression.
Frequently asked questions
Can a Baker's cyst go away on its own?
Yes, sometimes. When the knee problem behind it calms down, the cyst often becomes smaller or disappears. In other people it stays for a long time or comes back. Your doctor can tell you what to expect in your case.
Is a Baker's cyst dangerous?
Usually not. It is important to act quickly if the calf suddenly swells, turns red and hurts, because this needs to be checked by a doctor straight away.
Can I exercise with a Baker's cyst?
Gentle movement such as walking, cycling with low resistance or swimming is often fine. Avoid deep squats and kneeling if they increase the pressure behind the knee, and ask your physiotherapist which exercises suit you.
A sleeve you will actually wear
The best sleeve is the one that does not end up in a drawer. The KeenTrove Bamboo Knee Sleeve is made for exactly that:
- soft, breathable bamboo, comfortable even in summer
- fits snugly but does not dig in behind the knee
- does not lock the knee, so you move naturally
- wear it under your clothes during the day and in bed at night
With 60 days to get your money back, you have nothing to lose.
Note: this article is for information only and does not replace an examination by a doctor. If you have circulation problems or diabetes, or have recently had knee surgery, talk to your doctor before wearing compression.
