Definition- What is a bump on the knee?
Colloquially, a bulge is a bulge on a body part that is caused by tissue swelling, fluid retention or tissue proliferation. A bump on the knee is harmless in most cases. In most cases, it recedes within a short period of time without requiring special treatment. A medical examination should be carried out if there is severe pain or limited movement in the knee, if the bump keeps growing or if it does not disappear on its own after a few days. In some cases, treatment with medication or a minor surgical procedure may be necessary.
Causes
The possible causes of a bump on the knee are manifold and can be divided according to the trigger and the frequency of occurrence. Most bumps on the knee are caused by an injury to the knee joint. This can happen, for example, if you bump your knee or fall on your knees.
There is an increased accumulation of tissue fluid at the affected area, which leads to the formation of the bump. This is usually painful and can also be reddened and slightly overheated. In the event of a serious injury, such as in a traffic accident or as part of a sporting activity, ligaments, tendons or bones in the knee joint can also be injured, which often leads to additional swelling of the entire knee and a restriction of movement.
Another possible cause of a bump on the knee, which can occur even without previous injury, is the so-called Baker cyst. This is a bagging of the knee joint capsule, which surrounds the knee from the inside like a stocking. The bump occurs in the hollow of the knee and can be larger or smaller or even disappear completely for a time.
A large group of possible causes of a bump on the knee are also inflammations. Various structures in the knee can become inflamed or the entire joint can be affected. Quite common, for example, is an inflammation of a bursa, which has a cushioning function during movements in the knee.
Inflammation can be caused by germs penetrating the knee joint (for example after a medical intervention). On the other hand, an inflammation can occur in the context of a chronic disease with joint involvement, such as a chronic inflammatory bowel disease. In addition, a gastrointestinal infection can lead to a reactive inflammation with bulging of the knee.
A further cause is acute attacks of gout, in which an increase in uric acid levels causes crystals to precipitate in the joints. An exclusive infestation of the knee is rare but possible. On the other hand, an inflammation can occur in the context of a chronic disease with joint involvement, such as a chronic inflammatory bowel disease.
In addition, a gastrointestinal infection can lead to a reactive inflammation with bulging of the knee. A further cause is acute attacks of gout, in which an increase in uric acid levels causes crystals to precipitate in the joints. An exclusive infestation of the knee is rare but possible.
Many large joints have so-called bursa sacs, which take over a cushioning function under stress. In the knee joint there are several of them. These bursa sacs are susceptible to inflammation, which, in addition to pain, can make itself felt through a bump on the knee.
Triggers are often incorrect or excessive loading. Especially affected are people with a profession that puts a lot of strain on the knees, such as tilers or roofers. Often treatment by sparing, cooling and relieving is sufficient.
If necessary, the doctor will prescribe painkillers and possibly antibiotics. If inflammation of a bursa occurs repeatedly, it may have to be removed surgically. If a bump appears on the lateral knee, some of the possible causes of swelling are more likely than others.
Often it is an inflammation of the bursa, with pain, redness and overheating as additional symptoms. However, if the bump on the lateral knee shows no further signs of inflammation, it may also be a so-called meniscus ganglion. The outer and inner meniscus represent a kind of shock absorber in the knee joint.
If, for example, a twisting injury occurs (often in sports with rapid changes of direction), the meniscus can tear. As a result, a fluid-filled protrusion can form on the lateral knee. A meniscus ganglion more often starts from the outer meniscus.
What the bulge on the lateral knee is in the individual case can ultimately only be determined by a medical examination and, if necessary, imaging diagnostics. A bump on the knee resulting from a fall is harmless in most cases. By elevating the knee, cooling and protecting it, the bump usually disappears within a few days.
A doctor should be consulted if the whole knee swells up considerably, the pain is very severe and the knee can no longer be moved properly. If the bump does not go back after a few days, a doctor should also be consulted. A bump on the knee often occurs in the hollow of the knee.
In the majority of cases it is a so-called Baker cyst, which is a bulge in the joint capsule. This capsule surrounds the knee joint and all parts involved, such as ligaments, bones and menisci. The joint capsule is filled with joint fluid.
An increase in the fluid (for example due to an inflammatory process) or a heavy load on the knee can cause the capsule to bulge. Since the weakest part of the capsule is located in the hollow of the knee, the Baker cyst, which is often visible as a bump, develops there. In addition to a feeling of pressure and restricted movement, there may be sensations of discomfort in the lower leg due to depressed nerves.
In addition, the risk of a clot forming in the veins (thrombosis) is increased, as the blood vessels can also be squeezed by the cyst. In some cases the Baker cyst ruptures and the fluid is distributed throughout the leg. This is usually noticed by pain and by the fact that the bump on the knee is suddenly no longer there. Often, however, a Baker cyst never causes pain, so that the bump in the hollow of the knee does not need to be treated. Otherwise, surgical removal is indicated.
