Analgesic: A medication or treatment that relieves pain.
 
Ankylosing spondylitis: A rheumatic disease that causes arthritis of the spine and sacroiliac joints and, at times, inflammation of the eyes and heart valves.
 
Antibodies: Special proteins produced by the body's immune system that help fight and destroy viruses, bacteria, and other foreign substances (antigens) that invade the body. Occasionally, abnormal antibodies develop that can attack a part of the body and cause autoimmune disease. These abnormal antibodies are called auto antibodies.
 
Antigen: A foreign substance that stimulates an immune response.
 
Arthrography: An X-ray procedure that provides a detailed image of the joint when air or a contrast substance is injected into the joint space.
 
Arthroscopy: A procedure performed with an arthroscope (a small, flexible tube that transmits the image of the inside of a joint to a video monitor). Arthroscopy is used for diagnosis as well as treatment of some types of joint injury. The arthroscope is inserted through a small incision in the skin near the affected joint.
 
Aspiration: A procedure using a needle to remove body fluids for testing or as a treatment.
 
Bursa: (plural: bursae) A small sac of tissue located between bone and other moving structures such as muscles, skin, or tendons. The bursa contains a lubricating fluid that allows smooth gliding between these structures.
 
Bursitis: A condition involving inflammation of a bursa or bursae.
 
Cartilage: A resilient tissue that covers and cushions the ends of the bones and absorbs shock
 
Collagen: The main structural protein of skin, bones, tendons, cartilage, and connective tissue.
 
Connective tissue: The supporting framework of the body and its internal organs. Computed tomography (CT or CAT): A diagnostic technique that uses a computer and an X-ray machine to take a series of images that can be transformed into a clear and detailed image of a joint.
 
Corticosteroids: Powerful drugs similar to the hormones the body makes to fight inflammation. Glucocorticoids is a more precise term.
 
DMARDs: An acronym for disease-modifying antirheumatic drugs.
 
Fibromyalgia: A chronic disorder characterized by widespread musculoskeletal pain, fatigue, and tenderness in localized areas of the neck, spine, shoulders, and hips called "tender points."
 
Fibrous capsule: A tough wrapping of tendons and ligaments that surrounds the joint.
 
Flare or flare-up: A worsening of symptoms and pain in those with chronic disease.
 
Glucocorticoids: These powerful drugs are similar to the hormones the body makes to fight inflammation. Cortisone and prednisone are the best known. They are also called corticosteroids, but glucocorticoids is a more precise term.
 
Gout: A type of arthritis resulting from deposits of needle-like crystals of uric acid in the connective tissue, joint spaces, or both.
 
Homocysteine: An amino acid associated with heart disease and stroke. People with lupus often have high levels of homocysteine.
 
Hydrotherapy: Therapy that takes place in water.
 
Hyaluronan: The synthetic version of hyaluronic acid.
 
Hyaluronic acid: A substance in synovial fluid that lines the joints and acts as a shock absorber.
 
Hyperuricemia: High blood levels of uric acid, which can cause gout.
 
Infectious arthritis: Forms of arthritis caused by infectious agents, such as bacteria or viruses.
 
Inflammation: A typical reaction of tissue to injury or disease. It is marked by four signs: swelling, redness, heat, and pain.
 
Joint: The place where two or more bones are joined. Most joints are composed of cartilage, joint space, fibrous capsule, synovium, and ligaments.
 
Joint space: The area enclosed within the fibrous capsule and synovium.
 
Juvenile arthritis: A term used to refer to the types of arthritis that affect children. Juvenile rheumatoid arthritis is the most common type.
 
Ligaments: Stretchy bands of cord-like tissues that connect bone to bone.
 
Lupus: A type of immune disorder known as an autoimmune disease that can lead to inflammation of and damage to joints, skin, kidneys, heart, lungs, blood vessels, and brain.
 
Lyme disease: A bacterial infection spread by tick bites. Untreated, arthritis is sometimes a prominent symptom.
 
Magnetic resonance imaging (MRI): A diagnostic technique that provides high-quality cross-sectional images of a structure of the body without X-rays or other radiation.
 
Malar: A butterfly-shaped rash across the bridge of the nose and cheeks seen in those with lupus.
 
Manipulation: A treatment by which health professionals use their hands to help restore normal movement to stiff joints.
 
Mg/dl: Milligrams per deciliter, a unit of measurement denoting the proportion of solids in a liquid medium.
 
Microwave therapy: A type of deep heat therapy in which electromagnetic waves pass between electrodes placed on the patient's skin. This therapy creates heat that increases blood flow and relieves muscle and joint pain.
 
Mobilization therapies: A group of treatments that include traction, massage, and manipulation. When performed by a trained professional, these methods can help control a patient's pain and increase joint and muscle motion.
 
NSAIDs: Nonsteroidal anti-inflammatory drugs, a group of medications, including aspirin, ibuprofen, and related drugs, used to reduce inflammation that causes joint pain, stiffness, and swelling.
 
Osteoporosis: A disease that causes bones to lose density and become brittle. It is connected with heredity, and more common in older women and those who take glucocorticoids.
 
Osteoarthritis: A type of arthritis that causes the cartilage in the joints to fray and wear. In extreme cases, the cartilage may wear away completely.
 
Polymyalgia rheumatica: A rheumatic disease that involves tendons, muscles, ligaments, and tissues around the joints. Pain, aching, and morning stiffness in the neck, shoulders, lower back, and hips characterize the disease. It is sometimes the first sign of giant cell arteritis (a disease of the arteries characterized by inflammation, weakness, weight loss, and fever).
 
Polymyositis: A rheumatic disease that causes weakness and inflammation of muscles.
 
Psoriatic arthritis: Joint inflammation that occurs in about 5% to 10% of people with psoriasis (a common skin disorder).
 
Reactive arthritis: A form of arthritis that develops after an infection involving the lower urinary tract, bowel, or other organs.
 
Remission: A period when a chronic illness, such as arthritis, is quiet and there are no or few signs of disease.
 
Rheumatic: A term referring to a disorder or condition that causes pain or stiffness in the joints, muscles, or bone.
 
Rheumatoid arthritis: An inflammatory disease of the synovium, or lining of the joint, that results in pain, stiffness, swelling, deformity, and loss of function in the joints.
 
Rheumatoid factor: An antibody found in the bloodstream of some people with rheumatoid arthritis.
 
Rheumatologist: A doctor who specializes in diagnosing and treating disorders that affect the joints, muscles, tendons, ligaments, and bones.
 
Risk factor: Something that increases a person's chance of developing a disease, such as age, gender, ethnicity, and family history.
 
Scleroderma: A disease of the connective tissues and blood vessels that leads to hardening of the skin. Scleroderma can also damage internal organs such as the kidneys, lungs, heart, or gastrointestinal tract.
 
Synovial fluid: Fluid released into movable joints by surrounding membranes. The fluid lubricates the joint and reduces friction.
 
Synovium: A thin membrane that lines a joint and releases a fluid that allows the joint to move easily.
 
Tendinitis: Inflammation of tendons caused by overuse, injury, or related rheumatic conditions.
 
Tendon: Tough, fibrous cords of tissue that connect muscle to bone. Transcutaneous:
Through the skin.
 
Ultrasound: A treatment that uses sound waves to provide deep heat and relieve pain.
 
Viscosupplementation: This procedures involve the injection of gel-like substances (hyaluronates) into a joint to supplement the viscous properties of synovial fluid. Currently, these injections are approved for osteoarthritis of the knee joint, when more conservative treatments have failed.