Medical jargon is a barrier. It blocks your path to feeling better. If a clinic letter or appointment left you with more questions than answers, this glossary is for you. We have translated the most common arthritis words into plain English, grouped by topic so you can find what you need quickly.
Key insight: it is fine to ask
If a health professional uses a word you do not understand, ask them to explain it. You can also ask for a copy of your clinic letters. Arthritis UK has plain-English information on many arthritis conditions (Arthritis UK, n.d.a).
1. Conditions
Types of arthritis
| Condition | What it means |
|---|---|
| Acute CPP crystal arthritis | Sudden, painful joint swelling caused by calcium pyrophosphate crystals. It used to be called pseudogout. |
| Arthritis | An umbrella term for conditions that cause pain and inflammation in the joints. It is not one single disease. |
| Axial spondyloarthritis (axSpA) | Inflammatory arthritis that mainly affects the spine, causing long-term back pain and stiffness. It includes ankylosing spondylitis. |
| Gout | Inflammatory arthritis caused by a build-up of uric acid, which forms sharp crystals in a joint. |
| Lyme arthritis | Joint swelling that can develop in later-stage Lyme disease, a bacterial infection spread by ticks. |
| Osteoarthritis (OA) | The most common type of arthritis. The joint is constantly repairing itself, but cartilage thins and the joint changes. It is not simply 'wear and tear', and it can affect the knee, hip, hand, wrist, foot, ankle, spine, elbow or shoulder. |
| Palindromic rheumatism | Rare attacks of sudden joint pain and swelling that clear up completely, then come back. |
| Psoriatic arthritis (PsA) | Inflammatory arthritis linked to psoriasis, a skin condition. |
| Reactive arthritis | Joint pain and swelling that starts 1 to 4 weeks after an infection elsewhere in the body, usually a stomach bug or a sexually transmitted infection such as chlamydia (NHS, n.d.b). |
| Rheumatoid arthritis (RA) | An autoimmune condition where the immune system attacks the lining of the joints (the synovium), causing pain, swelling and stiffness. |
| Septic arthritis | A bacterial infection inside a joint. It is a medical emergency that needs hospital treatment with antibiotics. |
Autoimmune, vasculitis and related conditions
| Condition | What it means |
|---|---|
| Adult-onset Still's disease | A rare inflammatory condition causing high fevers, a salmon-pink rash and joint pain. |
| Antiphospholipid syndrome (APS) | An immune condition that makes blood more likely to clot. |
| Behçet's syndrome | A rare condition causing inflamed blood vessels, and mouth and genital ulcers. |
| Cryoglobulin-associated vasculitis | A rare condition where abnormal proteins in the blood clump together in the cold, blocking small blood vessels. |
| Eosinophilic granulomatosis with polyangiitis | A rare type of vasculitis, once called Churg-Strauss syndrome. It often starts with asthma and sinus problems in adulthood. |
| Fibromyalgia | A long-term condition where the brain and nerves process pain differently, causing widespread pain, tenderness and tiredness. |
| Giant cell arteritis (GCA) | Inflammation of arteries in the head and neck. It needs urgent treatment to prevent sight loss. |
| Granulomatosis with polyangiitis | A rare type of vasculitis that can affect the nose, sinuses, ears, lungs and kidneys. |
| IgA vasculitis (Henoch-Schönlein purpura) | Inflammation of small blood vessels causing a purple, spotty rash. It mostly affects children. |
| Kawasaki disease | A rare condition in young children where blood vessels become swollen, with a high fever that lasts several days. |
| Lupus (SLE) | An autoimmune condition that can affect many parts of the body, causing joint pain, extreme tiredness and skin rashes. |
| Microscopic polyangiitis | A rare, long-term type of vasculitis that can affect the lungs, kidneys and nerves. |
| Myositis | A group of rare conditions causing long-term inflammation and weakness in the muscles. |
| Polyarteritis nodosa (PAN) | A rare condition causing inflammation in small and medium-sized arteries. |
| Polymyalgia rheumatica (PMR) | An inflammatory condition causing pain and stiffness in the shoulders, neck and hips, usually worst in the morning. |
| Raynaud's phenomenon | Blood vessels in the fingers and toes narrow in the cold or under stress, so they turn white or blue and feel numb. |
| Sjögren disease | An autoimmune condition that attacks the glands that make tears and saliva, causing very dry eyes and mouth. |
| Systemic sclerosis (scleroderma) | A rare autoimmune condition that makes the skin and connective tissue hard and tight. |
| Takayasu arteritis | A rare type of vasculitis that mainly affects the aorta, the body's main artery, and its branches. |
| Vasculitis | An umbrella term for rare conditions that cause inflammation of the blood vessels. |
Arthritis in children and young people
| Condition | What it means |
|---|---|
| Juvenile idiopathic arthritis (JIA) | Arthritis that starts before the age of 16, where the immune system attacks the lining of the joints. |
| Oligoarthritis | The most common type of JIA, affecting about two-thirds of children with arthritis. It involves four or fewer joints, most often the knees (Arthritis UK, n.d.b). |
| Extended oligoarthritis | JIA that starts in four or fewer joints in the first 6 months, then spreads to five or more (Arthritis UK, n.d.c). |
| Polyarthritis | JIA affecting five or more joints in the first 6 months. |
| Systemic-onset JIA | JIA that affects the whole body, often starting with high fevers and a rash before joint pain. |
| Enthesitis-related JIA | JIA with inflammation where tendons attach to bone, such as the heel. |
Bone and connective tissue conditions
| Condition | What it means |
|---|---|
| Diffuse idiopathic skeletal hyperostosis (DISH) | Ligaments and tendons, especially around the spine, harden and turn to bone. |
| Joint hypermobility | Joints that move further than usual. For some people this causes pain and dislocations. |
| Osteomalacia | Soft, weak bones, most often caused by a lack of vitamin D. |
| Osteoporosis | Bones lose strength and density, so they break more easily. |
| Paget's disease of bone | The normal cycle of bone renewal is disrupted, so bones can become enlarged, weak or misshapen. |
Pain in specific areas
| Condition | What it means |
|---|---|
| Achilles tendinopathy | Pain and swelling in the tendon joining the calf to the heel, often from overuse. |
| Back pain and neck pain | Very common, and usually caused by strained muscles or stiff joints rather than serious disease. |
| Bursitis | Inflammation of a bursa, a small fluid-filled cushion near a joint, often at the elbow, knee or hip. |
| Calcific periarthritis | Calcium deposits around a joint, usually the shoulder, causing sudden, severe pain. |
| Carpal tunnel syndrome | Pain, tingling and numbness in the hand caused by a squeezed nerve in the wrist. |
| Complex regional pain syndrome (CRPS) | Severe, long-lasting pain in a limb, often after an injury. The cause is not fully understood. |
| Elbow, shoulder, hip and knee pain | Often caused by strained tendons, injuries or osteoarthritis, rather than inflammatory arthritis. |
| Foot, ankle, hand and wrist pain | Often linked to footwear, repetitive strain, tendon problems or osteoarthritis, such as at the base of the thumb. |
| Hammer toes | A toe bends down at the middle joint. Tight shoes or arthritis can cause it. |
| Plantar heel pain | Pain under the heel, often called plantar fasciitis. |
| Tibialis posterior dysfunction | The tendon supporting the arch of the foot becomes inflamed or torn, leading to a flat foot and pain. |
| Valgus heel | The heel tilts outwards, which changes the way you walk. |
2. Inside your joints
| Body part | What it means |
|---|---|
| Bursa | A small fluid-filled cushion that stops tendons and muscles rubbing against bone. |
| Cartilage | A smooth, rubbery layer covering the ends of bones, so they glide easily. |
| Enthesis | The point where a tendon or ligament attaches to bone. Inflammation here is called enthesitis. |
| Joint capsule | A tough bag of tissue that surrounds a joint and holds the fluid in. |
| Ligament | A strong band of tissue joining one bone to another, keeping the joint stable. |
| Synovial fluid | A thick, slippery liquid inside the joint that works like oil in an engine. |
| Synovium | The thin lining inside the joint capsule that makes synovial fluid. It swells in inflammatory arthritis. |
| Tendon | A strong cord joining a muscle to a bone, so the bone moves when the muscle tightens. |
3. Symptoms and clinical words
| Term | What it means |
|---|---|
| Autoimmune | When the immune system attacks the body's own healthy tissue. |
| Chronic | Long-lasting. |
| Crepitus | A grating, cracking or popping sound or feeling in a joint. |
| Erosion | Damage where bone or cartilage has worn away, often seen on X-rays. |
| Fatigue | Deep exhaustion that sleep does not fix. It is common in autoimmune conditions. |
| Flare (flare-up) | A period when symptoms suddenly get worse. |
| Inflammation | The body's response to injury or disease, causing heat, redness, swelling and pain. |
| Morning stiffness | Stiff joints on waking. In rheumatoid arthritis it often lasts longer than 30 minutes (NHS, n.d.a). |
| Nodules | Firm lumps under the skin near joints, which some people with rheumatoid arthritis develop. |
| Remission | A period when symptoms are much reduced or gone. |
| Systemic | Affecting the whole body, or several organs. |
4. Tests
| Test | What it means |
|---|---|
| ANA (antinuclear antibody) | A blood test that looks for antibodies which attack the body's own cells. A positive result can point towards conditions such as lupus, but many healthy people test positive too. |
| CRP and ESR | Blood tests that measure how much inflammation there is in the body. |
5. Medicines
| Medicine | What it means |
|---|---|
| Corticosteroids (steroids) | Strong anti-inflammatory medicines, often used short term to calm a flare while slower medicines start to work. |
| DMARDs | Disease-modifying anti-rheumatic drugs, such as methotrexate. They calm the immune system to control inflammatory arthritis and protect joints from damage. They are slow-acting and can take several weeks to work (Arthritis UK, n.d.d). |
| Intra-articular injection | An injection of medicine directly into a joint. |
| JAK inhibitors | A newer type of DMARD taken as a tablet, which blocks specific signals that drive inflammation inside cells. |
| NSAIDs | Non-steroidal anti-inflammatory drugs, such as ibuprofen, which reduce pain and swelling. |
| Topical treatments | Gels and creams rubbed onto the skin over a painful joint, such as NSAID gels or capsaicin cream. |
Key insight: give slow medicines time
DMARDs can take several weeks before you notice a difference, so keep taking them unless your rheumatology team tells you otherwise. Read more in The Pharmacy Fear Factor.
6. Therapies, self-management and support
| Term | What it means |
|---|---|
| Access to Work, Attendance Allowance and PIP | Government support for people with long-term conditions. Access to Work is a grant for help at work; Attendance Allowance and PIP are benefits that are not means-tested. |
| Ergonomics and home adaptations | Changing your workspace, equipment or home to fit your body and protect your joints. |
| Hydrotherapy | Exercise in a warm pool. The warmth relaxes muscles and the water supports your weight. |
| Let's Move with Leon | A free 12-week Arthritis UK programme of 30-minute exercise sessions for people with arthritis (Arthritis UK, n.d.e). |
| Occupational therapy (OT) | Help to carry on with daily tasks, by changing how you do them or using aids and equipment. |
| Orthotics | Insoles or supports that help a part of the body, such as the foot, work better. |
| Pacing | Breaking tasks into smaller chunks, with planned rests, to manage pain and tiredness. |
| Physiotherapy | Treatment using exercise and hands-on techniques to help you move better. |
| Podiatry | Care and treatment for the feet and lower legs. |
| Splinting | Using a support to rest or protect a painful joint. |
| TENS | A small device that sends mild electrical pulses through pads on the skin to reduce pain signals. |
| Thermal therapy | Using heat to relax muscles, or cold to numb pain and reduce swelling. |
7. Surgery and procedures
| Procedure | What it means |
|---|---|
| Arthrodesis (joint fusion) | An operation to join two bones together. The joint no longer moves, which can relieve severe pain. |
| Arthroplasty (joint replacement) | An operation to replace a damaged joint with an artificial one. |
| Arthroscopy (keyhole surgery) | Looking inside a joint with a tiny camera through a small cut. A knee 'washout' is not recommended for osteoarthritis unless the knee is locking (AoMRC, n.d.). |
| Osteotomy | An operation to cut and reshape a bone to change how a joint is aligned. |
| Synovectomy | An operation to remove some or all of the inflamed joint lining. |
8. Research words
| Term | What it means |
|---|---|
| Clinical trials (phases 1 to 4) | Stages of testing new treatments in people. Phases 1 to 3 test safety and whether it works before it is licensed. Phase 4 keeps checking safety once it is in use (NHS, n.d.c). |
| Placebo | A dummy treatment with no active medicine, used to compare against the real one in a trial. |
| Translational research | Turning discoveries in the laboratory into new treatments for patients. |
Where to get help
- Arthritis UK helpline: free advice on 0800 5200 520, Monday to Friday, 9am to 6pm (Arthritis UK, n.d.f).
- Local support: Arthritis UK In Your Area.
- Free guides: Arthritis UK's free information booklets.
- Aids and gadgets: our guide to arthritis aids and adaptations.
References
Academy of Medical Royal Colleges (n.d.) Knee arthroscopy for patients with osteoarthritis. Available at: https://ebi.aomrc.org.uk/interventions/knee-arthroscopy-for-patients-with-osteoarthritis/ (Accessed: 27 September 2026).
Arthritis UK (n.d.a) Conditions. Available at: https://www.arthritis-uk.org/information-and-support/understanding-arthritis/conditions/ (Accessed: 27 September 2026).
Arthritis UK (n.d.b) Oligoarthritis. Available at: https://www.arthritis-uk.org/information-and-support/understanding-arthritis/conditions/oligoarthritis/ (Accessed: 27 September 2026).
Arthritis UK (n.d.c) Extended oligoarthritis. Available at: https://www.arthritis-uk.org/information-and-support/understanding-arthritis/conditions/extended-oligoarthritis/ (Accessed: 27 September 2026).
Arthritis UK (n.d.d) Disease-modifying anti-rheumatic drugs (DMARDs). Available at: https://www.arthritis-uk.org/information-and-support/understanding-arthritis/arthritis-treatments/drugs/disease-modifying-anti-rheumatic-drugs-dmards/ (Accessed: 27 September 2026).
Arthritis UK (n.d.e) Exercising with arthritis. Available at: https://www.arthritis-uk.org/information-and-support/living-with-arthritis/health-and-wellbeing/exercising-with-arthritis/ (Accessed: 27 September 2026).
Arthritis UK (n.d.f) Arthritis UK helpline. Available at: https://www.arthritis-uk.org/information-and-support/support-and-resources/arthritis-uk-helpline/ (Accessed: 27 September 2026).
NHS (n.d.a) Rheumatoid arthritis: symptoms. Available at: https://www.nhs.uk/conditions/rheumatoid-arthritis/symptoms/ (Accessed: 27 September 2026).
NHS (n.d.b) Reactive arthritis. Available at: https://www.nhs.uk/conditions/reactive-arthritis/ (Accessed: 27 September 2026).
NHS (n.d.c) Clinical trials. Available at: https://www.nhs.uk/conditions/clinical-trials/ (Accessed: 27 September 2026).
Join the Zero Jargon Health Community
Threads · Instagram · Facebook
Important medical disclaimer
The content provided in this blog post is for educational and informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Always seek the advice of your GP, psychiatrist or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. Never start, stop or change a prescribed medicine without speaking to your prescriber first.
No comments:
Post a Comment