Glossary of Medical Terms used in JIA

The following list contains medical terms and definitions used in JIA.


Inflammation of the joints, the tendons end the tendon sheaths.


Antibodies are produced by the body to tight infection. The body can produce antibodies against itself called autoantibodies.

Autoimmune Diseases

Diseases caused by autoantibodies. (See immune system).


Inflammation of the bases of the fingers or toes.

Disease modifying drugs

Drugs used to halt or dampen down the disease process (e.g. methotrexate).


Inflammation of the tendon at the point where it attaches to bone.

Immune System

The body’s system for fighting infection. It includes antibodies which are molecules that recognise, and bind to, organisms and ‘foreign’ molecules. It also includes the white blood cells which can take up and kill organisms.


A drug that dampens down the immune system.


Part of the body’s normal process in dealing with injury or infection. There is an increased blood supply to the area, allowing the white blood cells access to the area. White blood cells produce substances which escalate this process. This causes the warmth, swelling and redness associated with an inflamed area.


Into the space within the joint. Applies to steroid injections placed into the joint space used to control the local inflammation within a specific joint.


Onset before the age of 16 years.


Bands of connective tissue uniting two bones. They help stabilise joints, and are usually unstretchable.

Non-steroidal Anti-inflammatory Drugs (NSAIDs)

Drugs which dampen down inflammation and are not steroids, e.g. ibuprofen.

Occupational Therapy

Provides splints to support inflamed joints, and assesses the need for help to maintain physical independence.

Pauci-articular JIA

Arthritis affecting up to 4 joints.

Polyarticular JIA

Arthritis affecting more than 4 joints.


Exercise programmes designed to improve and maintain the range of movement of joints, and to maintain muscle power and stamina to stabilise joints and improve fitness.

Range Of Movement (ROM)

The angle that a joint can move through. This is often decreased by inflammation.

Reactive Arthritis

Arthritis following infections such as tonsillitis or gut infections.

Sacroiliac Joints

Triangular bone at the base of the spine (the sacrum) where it joins the pelvis (the sacroiliac joint).

Septic Arthritis

Arthritis due to infection within the joint.


Supports made for joints that are inflamed to rest them and maintain them in a good functional position.


A type of arthritis that can ultimately affect mainly the back, the sacroiliac joints, the pelvis which connects the lower limbs to the body, the feet and other joints in the lower limbs. The hands can also be affected.


A family of drugs, some of which are very effective at reducing inflammation.

Still’s Disease

Systemic onset JIA.

Systemic Onset JIA

A type of arthritis that starts with ‘systemic’ symptoms: fever, rashes, poor appetite, lethargy and enlarged glands.


Inflammation of the synovium. The synovium is the tissue which lines the joint space.


Fibrous tissue connecting muscle to bone.


Inflammation of the synovial sheaths surrounding tendons.


Inflammation of tendons.


Inflammation within the eye associated with some forms of arthritis.


Inflammation affecting blood vessels.

Written By: Dr C. Pilkington, Senior Registrar, Great Ormond Street.

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