Definition
The knee, also known as the knee joint, is the connection between the thigh bone and the shin bone and the kneecap. It is the largest joint in the human body and is a common location for a number of different diseases. The swelling of the knee joint is usually the expression of an inflammation as a reaction to an injury, wear and tear of cartilage parts or an infection.
Swelling of the knee joint is usually referred to as a knee joint effusion. This is a pathological accumulation of fluid in the joint. Depending on the underlying disease, the type of fluid can be either bloody, purulent or clear.
Causes
The causes of knee swelling are many and varied. In general, a distinction must be made between different categories. Among the causes are: The swelling itself is usually caused by an accumulation of fluid in the knee joint.
This is influenced by so-called inflammation mediators, which are released during the above-mentioned diseases. One of the most common causes of knee swelling is knee joint arthrosis. In this case, wear and tear of the cartilage parts of the knee joint and the associated inflammation occur.
In other cases, the onset of rheumatoid arthritis is responsible for the swelling. The cause of this chronic inflammatory disease is largely unknown, although an autoimmune component is suspected. This means that the patient’s own immune system attacks parts of the joint and thus leads to inflammation of the joint.
An injury to the knee joint, for example in the form of an accident or surgery, also causes swelling. This leads to an injury of structures and an associated inflammation. Sports injuries caused by gross violence to the knee such as kicks or blows often manifest themselves as painful bruises with swelling.
This is a so-called horse kiss. In rare cases, certain types of cancer can also be responsible for the swelling. Especially in children and adolescents, a knee swelling of unknown cause should be clarified.
In order to finally clarify the reason for the individual swelling of the knee, a detailed clarification is recommended during a visit to the doctor. Specialists in the investigation of knee joint swelling are orthopedic specialists and trauma surgeons.
- Injuries (e.g.
a torn meniscus)
- Infections (e.g. an inflammation in the knee)
- Incorrect charges
- Metabolic diseases
- Wear
- Tumor Diseases
Among a variety of other causes, an infection with certain bacteria, the Borrelia bacteria, can cause a disease known as Lyme disease. The infection with the bacteria is usually caused by a tick bite, as these are the main carriers of the bacteria. An indication of whether a Borrelia infection has occurred can be the so-called traveling redness, a red circle on the skin that gets bigger and bigger over time before it disappears.
If the infection remains untreated, a reactivation of the infection can lead to an inflammation of the knee joint. An inflammation of the joint caused by Lyme disease is also called Lyme arthritis. Lyme disease can be treated with certain antibiotics.
Nevertheless, Lyme disease is a dangerous disease, because in addition to the knee joint, the nervous system and various organs can also be affected. Especially in the late stages of the disease, a complete elimination of the bacteria in the body is not always successful. Surgery of the knee joint is very common in Germany.
Orthopedic interventions on the knee joint are usually necessary, the most common being operations due to knee joint arthrosis. Every operation causes injuries to the structures involved in the knee joint and the surrounding tissue. After the operation, the body reacts to the injuries caused by the operation by releasing so-called inflammation mediators.
In addition to healing of the injured tissue, these also lead to an accumulation of fluid in the joint and thus to knee swelling. The knee swelling cannot be prevented after surgery. However, it does help to cool the knee joint and to elevate it, as well as not to put any weight on the affected leg after the operation.The swelling should subside significantly after a few days or a few weeks, depending on the procedure performed and the injured structures.
