• Ankylo-: a prefix meaning crooked or bent; refers to stiffening of the joint
• Antibody: a protein produced by the lymphocytes to fight foreign proteins (antigens)
• Antigen: a foreign protein or carbohydrate complex that causes an immune response
• Antigen-presenting cell: white blood cells that encounter an invading organism, digest it, and present an antigen on their cell surface
• Arthr-: a prefix meaning “joint”
• Arthritis: inflammation of a joint, causing pain, stiffness, swelling, and redness
• Arthrocentesis: removing synovial fluid from a joint
• Arthropathy: general term for joint disorder
• Arthroscopy: examination of the interior of a join with an endoscope
• Arthroplasty: surgical replacement of all or part of a joint
• Articular cartilage: tough, rubbery tissue that forms the surface of bones within joints
• Autoimmune disease: a condition caused when an individual’s immune system reacts against his or her own organs and tissues
• B lymphocyte: white blood cell that produces antibodies
• Bursa: a protective, fluid-filled sac around a ligament, tendon, or muscle
• Bursitis: inflammation of the bursa causing swelling and pain
• Cartilaginous joint: tough cartilage plate that permits slight movement
• Chondrocyte: cell embedded in cartilage that produces cartilage
• Collagen: the main structural protein in connective tissues
• Collagenase: an enzyme that breaks down collagen
• Computed tomography (CT): a diagnostic technique in which X-rays are taken in many different directions and the resulting data synthesised by a computer to generate cross-sectional and other images of the body
• Conjunctivitis: inflammation of the eye’s outer membrane
• Connective tissue: the material that holds various body structures together; cartilage, tendons, ligaments, and blood vessels are composed entirely of connective tissue
• Crepitus: a crackling sound or grating sensation in a joint, caused by swollen synovium or bone surface rubbing together
• Cytokine: “messenger” molecule that allows cells to communicate and alter one another’s function
• Dermatomyositis: a rate disease in which the muscles and skin become inflamed; muscles become weak, stiff, and painful
• Diathermy: physical therapy using high-frequency electric current, ultrasound, or microwave to deliver heat to muscles and ligaments
• Discoid lupus erythematosus: a mild form of lupus affecting mainly the skin
• Elastin: a stretchable protein found in connective tissue
• Enteropathic: originating from the gastrointestinal tract
• Erythrocyte sedimentation rate (ESR): a diagnostic test for inflammatory diseases that measures the rate at which red blood cells sediment from a well-mixed specimen of blood
• Enthesis: the site where a ligament attaches to bone
• Enzyme: any protein that regulates chemical changes in other substances
• Fixed joint: thin brands of fibrous tissue the connects the plate-like bones of the skull
• Flare: reappearance or worsening of symptoms
• Gout: arthritis caused by urate crystals in the joint
• Heberden’s node: bony growth on the joint nearest the fingertip
• Human leukocyte antigen (HLA): a type of receptor on cells involved in recognising foreign antigens; some are associated with different types of arthritis
• Hyperuricaemia: an abnormally high level of uric acid in the blood; may lead to the development of gout
• Infectious arthritis: arthritis caused by invading microorganisms
• Inflammation: response to injury or foreign invasion designed to protect the body; the symptoms are heat, redness, swelling, and pain
• -itis: suffix meaning “inflammation”
• keratoconjunctivitis sicca: persistent dryness of the eye that sometimes occurs in rheumatoid arthritis and several other disorders
• keratoderma blenorrhagica: a skin disorder that may occur in Reiter’s syndrome
• leukotriene: powerful chemical involved in inflammation and blood flow
• ligament: tough, elastic tissue that keeps bone in a joint aligned
• Lyme disease: a disease transmitted by the bite of tick; characterised by skin changes, flulike symptoms, and joint inflammation
• Lymphocyte: a type of white blood cell
• Macrophage: a type of phagocyte or white blood cell that digests foreign invaders and damaged tissues
• Magnetic resonance imaging (MRI): a diagnostic technique in which radio waves generated in a strong magnetic field are used to provide information about the hydrogen atoms in different tissues within the body; a computer uses this information to produce images of the tissues in many different planes
• Major histocompatibility complex (MHC): the area on chromosome 6 containing genes that determine the structure of human leukocyte antigen (HLA) molecules
• Monoclonal antibody: an antibody produced by means of recombinant DNA technology to recognise one specific substance
• Ossification: the process by which bone is formed
• Osteotomy: an operation in which the bone is cut to change its alignment or shorten or lengthen it
• Osteomyelitis: bone infection, caused usually by bacteria but sometimes by fungi
• Osteophyte: an outgrowth of bone
• Pannus: proliferation of synovial tissue
• Phagocyte: white blood cell that ingests bacteria and other foreign molecules
• Polymyositis: a rare disease in which the muscles become inflamed and weak
• Prostaglandins: chemicals that produce pain and inflammation
• Psoriasis: a common skin disease characterised by thickened patches of inflamed red skin, sometimes accompanied by painful joint swelling and stiffness
• Reactive arthritis: joint problems triggered by bacterial or viral infection elsewhere in the body
• Remission: period during which symptoms of a disease diminish or disappear
• Rheumatic disease: any one of over 100 disorders that cause chronic joint pain
• Rheumatism: pain and stiffness of soft tissues in and around joints
• Rheumatoid factor: an antibody found in about 80% of people with rheumatoid arthritis; also appears in other diseases and sometimes in healthy people
• Rheumatology: the branch of medicine devoted to the study and treatment of connective tissue diseases
• Sacroiliitis: inflammation of the sacroiliac joints (one of a pair of joints between each side of the sacrum and the pelvis)
• Sacrum: the larger triangular bone at the base of the spine
• Sausage digit: a toe or finger swollen and red along its entire length
• Scintigraphy: a diagnostic technique based on the detection of radiation emitted by radioactive substances injected into the body; also called radionuclide scanning
• Scleroderma: an autoimmune disease in which the skin thickens and hardens; sometimes other parts of the body are affected and joint pain may result
• Suture: another name for fixed joints in the skull
• Synovial fluid: a viscous, translucent fluid found within the joints and bursa
• Synovial joint: the most mobile type of joint; found in the shoulders, wrists, fingers, hips, etc
• Synovitis: inflammation of the synovium
• Synovium: a thin membrane lining joint capsules that produces synovial fluid
• Systemic lupus erythematosus (SLE): a connective tissue disease that can affect internal organs, nervous system, skin, and joints
• T lymphocyte: white blood cell that destroys abnormal cells or interacts with B-lymphocytes
• Tendinitis: inflammation of the tendon, usually caused by injury, which may restrict movement of the muscle attached to the tendon
• Tendon: tough, fibrous band of tissue that attaches muscle to bone
• Ultrasound: a diagnostic technique in which high-frequency sound waves penetrate the body, bounce around, and produce multiple echoes; these echo patterns can be viewed as an image on a computer screen
• Urethritis: inflammation of the urethra
• Uveitis: inflammation of the pigmented part of the eye that may seriously affect vision
• Vasculitis: inflammation of blood vessels.

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