Swelling in the kneecap is usually called Baker cyst. A Baker cyst occurs when the mucus sac on the back of the knee contains extra fluid.
Swelling of the knee joint is usually due to overload of the knee while having problems in the knee joint. Some common factors are:
- A meniscus injury
A Baker cyst consists of fluid that has settled into the mucus sac on the back of the knee. The fluid is joint fluid, so-called “synovial fluid”. This fluid is found in the joints of the body, including the joints in our knees, fingers and elbows. The joint fluid acts as a kind of lubricant in moving joints.
Symptoms of Baker cyst
When the knee crease becomes swollen and you get a Baker cyst, a swelling occurs which can be anything from hazelnut to a tennis ball. Pain is not always a symptom. A large swelling of the knee joint can make the knee feel tense. It can also be difficult to bend the knee joint as usual. The swelling can sometimes extend to the calf.
A Baker cyst can crack in unusual cases. In these cases, pain occurs and the calves become sore, swollen and warm as a result of the bleeding. The symptoms can be exacerbated by physical activity or by standing up for a long time.
How is swelling of the knee joint treated?
A swelling in the kneecap usually goes away by itself over time. In most cases, Baker cysts decrease or disappear. Adults with knee swelling usually do not need treatment unless the swelling hurts. Children also usually do not need any treatment. In adults, the underlying cause, such as osteoarthritis or inflammation, may need to be treated.
Even a Baker cyst with bleeding usually heals itself. However, it usually takes several weeks. When you have a cracked Baker cyst you should have your legs in high position and use compression stockings or pressure dressings. If the bleeding cyst hurts, you can relieve it with non-prescription pain medication. In case of serious problems, the swelling of the knee joint can be removed.
If you suffer from knee arthritis there is a greater risk of the swelling recurring.
Care and diagnosis of swelling of the knee
You should seek care at a health care center if you have a swelling of the knee joint that does not go away on its own after two weeks. A Baker cyst is usually diagnosed by the doctor examining the affected knee and feeling the swelling of the knee joint. It can be good to seek care to rule out that the swelling has not occurred for any other reason.
Sometimes blood or joint fluid samples are taken to see if the knee has an inflammation that may have caused the swelling. In unclear cases, a magnetic camera or ultrasound can be used to determine that it is a Baker cyst.