A Baker's cyst, also known as a popliteal cyst, is a sac of fluid that forms behind the knee.
Baker's cysts tend to feel hard when the knee is fully extended and soft when the knee is bent. Physical therapists call this change in density Foucher's sign.
However, this type of cyst can cause pain or swelling, which can limit movement.
Baker's cysts sometimes go away without treatment. A doctor is unlikely to recommend medical intervention unless the cyst causes discomfort or difficulty moving the knee.
A number of remedies and exercises can help reduce any symptoms of Baker's cysts and prevent them from forming. Keep reading to learn more.
Exercises that focus on preserving the knee's range of motion may ease pain and prevent muscle weakness.
However, before trying any exercise for a Baker's cyst, speak to a doctor or physical therapist. The wrong exercise may injure the knee, intensifying pain.
The following exercises may benefit a person with a Baker's cyst:
Standing calf stretch
- Stand up straight in front of a chair or another heavy piece of furniture, and use it for balance, if necessary.
- Step back with the right leg, then bend both knees until there is a stretch.
- Hold this stretch for 20 seconds, then switch sides.
- Sit in a chair with both feet flat on the floor and the knees at a 90 degree angle.
- Lift one heel while keeping the ball of the foot on the floor.
- Push the top of the knee down to flatten the foot. Repeat this 10 times, then switch sides.
- Sit on the floor with the legs extended straight out in front of you.
- Loop a towel or exercise band under the balls of the feet, then gently pull backward.
- Hold the stretch for 10 seconds, then switch sides.
Baker's cysts often form as a result of a knee injury. During recovery, walking may help a person gradually regain strength and mobility.
However, if a person needs to change their gait or contort a knee into an unusual position to walk comfortably, it may not be safe to walk yet. Consult a doctor or physical therapist.
The following home care strategies may help alleviate symptoms of a Baker's cyst or prevent one from forming:
- Apply ice or cold packs to the cyst to reduce pain and swelling.
- Apply heat to the area. Some people find that alternating ice and heat works well.
- Take nonsteroidal anti-inflammatory drugs such as acetaminophen or ibuprofen.
- Avoid any activities that cause pain. If walking is painful, use crutches to reduce pressure on the injured knee.
- Gently massage the area around the cyst to ease any pain and help reduce inflammation.
A Baker's cyst often appears following a knee injury. Preventing knee injuries is, therefore, the best way to prevent these cysts from developing.
To avoid injuring the knee:
- Wear supportive shoes that fit well.
- Warm up before exercise and sports, and cool down afterward.
- Refrain from exercising on a knee that is already tender and painful.
- Seek treatment for any knee, leg, or foot injuries — an injury to one area of the body can increase the risk of falls and further harm.
The knee, like other joints, contains fluid-filled sacs called bursae. The fluid helps lubricate the joint so that it can move smoothly.
When the knee secretes too much of this fluid, the bursae can swell, causing a Baker's cyst to form. These cysts may be painful and make it harder to move the knee.
Usually, Baker's cysts appear after an injury, such as a fall. They can also develop in people with chronic joint conditions. Sometimes, there is no clear cause.
Risk factors include:
- Overuse and injury: Injuries such as falls or sudden blows, as well as chronic overuse, can cause these cysts. They often form when there is a tear in the knee's cartilage.
- Inflammatory joint diseases: People with rheumatoid arthritis and osteoarthritis may be more likely to develop these cysts.
Even if a Baker's cyst is not causing symptoms, it is important to see a doctor for an accurate diagnosis.
Other conditions, including deep vein thrombosis, a dangerous blood clot, can mimic features of a Baker's cyst.
It is also important to see a doctor if:
- The cyst appears to be growing.
- The cyst becomes painful.
- The cyst makes it difficult to walk or move the knee.
- Treatment stops working.
- Symptoms get worse.
- The cyst causes numbness in the knee or leg.
Pain or numbness can occur when cysts grow large enough to press on surrounding structures, damaging blood vessels or nerves.
Anyone interested in using exercise to ease pain and improve mobility should consult a doctor or physical therapist.
It is especially important to seek expert guidance before trying rigorous weight-bearing exercises.
If a Baker's cyst is causing pain and not responding to remedies and exercises, a doctor may recommend other treatment methods.
Corticosteroid injections may temporarily relieve pain and support healing. If they do not work, the doctor may use a needle to extract the fluid from the cyst.
If these treatments are ineffective, the doctor may recommend surgery to remove the cyst. This would prevent it from refilling with fluid or swelling so much that it injures the knee joint or affects the person's ability to walk.
While most Baker's cysts do not cause symptoms, some can cause swelling and pain.
Many go away on their own, but a variety of remedies, exercises, and medical treatments can help resolve these cysts.
It is important to consult a doctor about any new lump or bump on the body before trying to treat it at home.