Condition guide
A Baker’s cyst is a swelling filled with joint fluid that forms behind the knee. In adults it is usually the result of another knee problem, such as osteoarthritis or a meniscus tear; when that problem is treated, the cyst usually settles too. It is mostly not dangerous, but if it causes sudden swelling and pain in the calf it needs prompt assessment, because it can be confused with a blood clot in the leg.
If the cyst bursts, its fluid leaks into the calf; there may be sudden pain, swelling, tightness and redness in the calf. These symptoms are very similar to a clot in a deep leg vein (deep vein thrombosis), and an examination and tests are needed to tell them apart. Redness can be harder to see on darker skin.
When it is painful, you can rest your knee and raise your leg on a pillow when sitting.
You can apply ice wrapped in a towel for 10–20 minutes, without letting it touch your skin directly.
Ibuprofen or paracetamol can reduce pain and swelling. If you have asthma, high blood pressure, or kidney, heart or stomach problems, you can check with your doctor or pharmacist first.
A knee support from a pharmacy can give support. As symptoms ease, keeping your knee moving and strengthening your muscles is important.
For common causes of the cyst, see the knee osteoarthritis and meniscus tear guides.
Exercises at home
Do the movements slowly and with control, within a pain-free range. If you notice new swelling or pain in your calf, stop exercising and see your doctor.
Lie on your back with your legs straight. Slide one heel along the floor towards your buttock, bending your knee as far as is comfortable; you may feel a mild tightness behind the knee, but don’t push into pain. Then slowly slide it back.
10 reps on each leg, twice a dayLie on your back or sit with your leg stretched out, and place a rolled-up towel under your knee. Press the back of your knee down into the towel; the muscle at the front of your thigh will tighten and your heel will lift slightly. Hold for 5 seconds.
10 reps, 2–3 times a daySit up straight on a chair. Slowly straighten one knee and lift your leg until it is parallel to the floor, tightening the muscle at the front of your thigh. Hold for 5 seconds, then lower slowly.
10 reps on each leg, twice a dayLie on your back and bend one knee. Keeping the other knee straight and tightening your thigh, lift that leg up to the level of your bent knee. Lower it slowly.
10 reps on each legStand upright holding onto a worktop. Lift both heels together and rise onto your toes, pause for 2 seconds and lower slowly. The calf muscles are important for recovering your balance when walking.
10–15 repsCross your arms over your chest. Lean slightly forward and stand up from the chair, then sit back down with control. If it is hard, push up with your hands or use a higher chair.
10 reps, 1–2 times a dayIt can, and this is common in children. In adults, because the cyst usually comes from another knee problem, symptoms often improve once that problem is treated. Recovery can take from a few months to a few years.
Draining it can relieve symptoms, but the cyst often fills up again, and it may not work for long-standing cysts. A steroid injection, which can be given after draining, can reduce pain and inflammation but does not stop the cyst coming back.
Usually not. Removing the cyst itself is rare; surgery is mainly considered to repair significant damage inside the knee, such as a meniscus tear, or for large, painful cysts that have not improved with other treatments.
Yes. Keeping the knee moving and strengthening the muscles around it is recommended. You can cut down for a while on movements that markedly increase the tightness behind the knee, and work within a pain-free range.
Sources
More from the health library
®