Synonym: joint inflammation English: arthritis Arthritis is an inflammation of the joints that can occur in connection with various diseases. Therefore, a distinction is made between different forms of arthritis, see Causes. Arthritis manifests itself through the typical symptoms of inflammation: The joint is reddened, swollen, overheated and painful.

If only a single joint is affected, it is called monoarthritis. If several joints are involved, however, it is called oligoarthritis. The term polyarthritis is used when many joints are affected.

An arthritis in the area of the spine is called spondyloarthritis. A distinction must be made between arthritis and osteoarthritis, in which the joint is initially damaged not by inflammation but by wear and tear. However, arthrosis in an advanced stage can lead to arthritis.


The two most common causes of arthritis are infections and autoimmune diseases. In addition, there are the so-called crystal arthropathies, in which crystal deposits in the joint cause inflammation, as well as rarer special forms of arthritis. Infectious or septic arthritis is mostly caused by bacteria.

However, infection of the joint with viruses or fungi can also lead to arthritis. The pathogens can enter the joint in the following ways: via the blood (haematogenous spread), for example in the case of blood poisoning (sepsis) by opening the joint space, either in the event of injury or during medical interventions (punctures, operations) carried out in a non-sterile manner by spreading a neighbouring infection of the soft tissues (for example after hip joint replacement) or the bone (osteomyelitis) In addition, arthritis can occur as a symptom of a Lyme disease infection following a tick bite (Lyme arthritis). A large subgroup of arthritis occurs in the context of autoimmune diseases.

These are characterised by the fact that the immune system is directed against the patient’s own body. If parts of the joint such as the joint cartilage or the joint mucosa are attacked, arthritis can develop. The most common form of such an autoimmune joint inflammation is rheumatoid arthritis, popularly known as rheumatism.

In addition, the following autoimmune diseases can lead to joint involvement: Psoriasis Systemic lupus erythematosus Sjögren’s syndrome Scleroderma Dermatomyositis Bechterew’s disease (ankylosing spondylitis) Chronic inflammatory bowel diseases (Crohn’s disease, ulcerative colitis, Whipple’s disease) Sarcoidosis Vasculitis (vasculitis) such as Wegener’s disease A special form of immune-related arthritis is the so-called reactive arthritis. In this case, arthritis occurs after a bacterial infection of the gastrointestinal tract, the urinary tract, the reproductive organs or the respiratory tract, although the mechanism of its development has not yet been finally clarified. One assumption is that the bacteria have components on their surface that resemble the body’s own molecules of cells in the joint.

After successfully fighting the bacteria, the immune system may also recognize these molecules as foreign and therefore trigger an immune reaction against the body’s own cells. This type of “mix-up” is also known as cross-reactivity. Another theory says that after the infection is over, components of the pathogens remain behind, are deposited in the joint and thus reactivate the immune system.

If urethritis and conjunctivitis are added to the reactive arthritis as such a secondary disease after an infection, one speaks of Reiter’s syndrome or Reiter’s triad. Another cause of arthritis is the so-called crystal arthropathies. Here, the deposition of crystals in the joint leads to an inflammatory reaction.

The best-known form of crystal arthropathy occurs in the context of gout disease, in which crystals of uric acid are formed (arthritis urica). Less frequently, arthritis is caused by calcium pyrophosphate crystals, which are deposited in the cartilage in the case of pseudo-gout (chondrocalcinosis), or by apatite crystals, which are formed in the case of hydroxyapatite disease. Arthritis can also be caused by joint wear in osteoarthritis, and by joint bleeding in haemophilia. – via the blood (haematogenic scattering), for example in the case of blood poisoning (sepsis)

  • By opening the joint space, either in case of injuries or in case of non-sterile medical interventions (punctures, operations)
  • Through the spread of a neighbouring infection of the soft tissues (for example after hip joint replacement) or the bone (osteomyelitis)
  • Psoriasis
  • Systemic lupus erythematosus
  • Sjögren’s Syndrome Sjögren
  • Scleroderma
  • Dermatomyositis
  • Ankylosing spondylitis
  • Chronic inflammatory bowel diseases (Crohn’s disease, ulcerative colitis, Whipple’s disease)
  • Sarcoidosis
  • Vascular inflammation (vasculitis) like Wegener’s disease