What Is Arthritis?
Arthritis is a general term for conditions that cause pain, swelling, stiffness or damage in the joints. A joint is the place where two bones meet, such as the knee, hip, finger or spine.
Arthritis is not one disease. Some types happen because joint cartilage wears down over time. Others happen because the immune system attacks the joints, or because crystals build up inside them.
Arthritis is very common. According to the World Health Organization (WHO), about 528 million people worldwide were living with osteoarthritis in 2019, and the knee was the most commonly affected joint. A Global Burden of Disease study estimated that 55.8 million people had gout in 2020.
Arthritis can affect people of any age, including children. It is more common with older age, in women for most inflammatory types, and in men for gout.
Types of Arthropathy
"Arthropathy" is the medical word for any disease of a joint. Arthritis is one kind of arthropathy, where inflammation is involved. Doctors usually group the types of arthropathy by what causes the joint damage:
- Degenerative arthropathy: Cartilage that cushions the joint wears down over time (Examples: Osteoarthritis)
- Inflammatory (autoimmune) arthropathy: The immune system attacks the joint lining (Examples: Rheumatoid arthritis, psoriatic arthritis, juvenile idiopathic arthritis)
- Spondyloarthropathy: Inflammation of the spine, sacroiliac joints and the places where tendons attach to bone (Examples: Ankylosing spondylitis, psoriatic arthritis, reactive arthritis, enteropathic arthritis (linked to IBD))
- Crystal arthropathy: Crystals form inside the joint and trigger sudden inflammation (Examples: Gout (uric acid crystals), pseudogout or CPPD (calcium crystals))
- Infectious (septic) arthropathy: Bacteria, viruses or fungi infect the joint (Examples: Septic arthritis, viral arthritis such as after chikungunya)
- Arthropathy linked to other diseases: Joint damage caused by another condition (Examples: Lupus, diabetic (Charcot) arthropathy, haemophilic arthropathy)
Knowing the group matters because treatment is very different. For example, gout is treated by lowering uric acid, while rheumatoid arthritis needs medicines that calm the immune system.
Common Types of Arthritis
1. Osteoarthritis (OA)
Osteoarthritis is the most common type of arthritis. The smooth cartilage at the ends of bones slowly breaks down, so bones rub together.
It mostly affects the knees, hips, hands and spine. Pain usually gets worse with activity and better with rest. Morning stiffness is short, usually less than 30 minutes.
Age, extra body weight, past joint injury, repetitive strain and family history raise the risk.
2. Rheumatoid Arthritis (RA)
Rheumatoid arthritis is an autoimmune disease. The immune system attacks the lining of the joints (the synovium), causing swelling and, over time, joint damage.
RA usually affects small joints of the hands and feet on both sides of the body. Morning stiffness often lasts more than an hour. Tiredness, low-grade fever and weight loss can also occur.
RA is more common in women. It can also affect the lungs, eyes, heart and blood vessels, so early treatment is important.
3. Psoriatic Arthritis (PsA)
Psoriatic arthritis is inflammatory arthritis that develops in some people with psoriasis, a skin condition with red, scaly patches. Up to 30% of people with psoriasis may develop it. In some people, joint symptoms start before the skin rash.
Signs that point to psoriatic arthritis include:
- Swelling of a whole finger or toe, called "sausage digit" (dactylitis)
- Pain where tendons attach to bone, such as the heel or Achilles tendon (enthesitis)
- Nail pitting, ridges or nails lifting from the nail bed
- Joint pain on one side of the body, or in the lower back
- Red, itchy, scaly skin patches on the scalp, elbows or knees
The RA factor test is usually negative in psoriatic arthritis. This helps doctors tell it apart from rheumatoid arthritis.
4. Gout
Gout is a type of crystal arthritis. It happens when uric acid levels in the blood stay high for a long time and sharp urate crystals form inside a joint.
A gout attack usually starts suddenly, often at night. The joint becomes very painful, red, hot and swollen. Even a bedsheet touching it can hurt. The big toe is the most common site, but the ankle, knee, wrist and fingers can also be affected.
Common gout triggers and risk factors:
- Alcohol, especially beer and spirits
- Red meat, organ meat and some seafood
- Sugary drinks and juices high in fructose
- Dehydration or crash dieting
- Being overweight, high blood pressure, diabetes or kidney disease
- Some medicines, such as certain diuretics (water pills)
Without treatment, attacks can become more frequent. Over years, lumps of crystals called tophi can form under the skin, and kidney stones can develop. A uric acid test helps diagnose gout and track treatment.
5. Ankylosing Spondylitis (AS)
Ankylosing spondylitis is a long-term inflammatory arthritis that mainly affects the spine and the sacroiliac joints, where the spine meets the pelvis. It is part of a group called axial spondyloarthritis.
The typical symptom is inflammatory back pain that:
- Starts before age 45, often in the late teens to 30s
- Comes on slowly and lasts more than 3 months
- Is worse in the morning or after rest
- Improves with exercise and movement
- May wake you in the second half of the night
Ankylosing spondylitis can also cause heel pain, painful red eyes (uveitis) and reduced chest expansion. In advanced cases, bones in the spine can fuse, causing a stiff, bent posture.
Most people with ankylosing spondylitis carry the HLA-B27 gene. However, most people who carry HLA-B27 never develop the disease, so the HLA-B27 test supports a diagnosis but does not confirm it alone.
Other Types of Arthritis
- Juvenile idiopathic arthritis: arthritis that starts before age 16.
- Reactive arthritis: joint inflammation after a gut or urinary infection.
- Septic arthritis: a joint infection. A single hot, swollen joint with fever is a medical emergency.
- Lupus arthritis: joint pain linked to systemic lupus erythematosus, an autoimmune disease.
- Pseudogout (CPPD): calcium crystals in the joint, often in the knee, in older adults.
Common Symptoms of Arthritis
Arthritis symptoms depend on the type, but most people notice one or more of these:
1. Joint Pain
Pain may be dull and constant, come and go, or start suddenly and severely, as in gout.
2. Stiffness
Joints may feel stiff after waking up or after sitting for a long time. Stiffness that lasts more than 30 to 60 minutes in the morning often points to inflammatory arthritis.
3. Swelling
The joint may look puffy or feel soft and full because of fluid or inflamed tissue.
4. Redness and Warmth
The skin over the joint may look red and feel warm. This is common in gout and septic arthritis.
5. Reduced Range of Movement
You may find it hard to fully bend or straighten a joint, climb stairs, grip objects or turn your neck.
6. Symptoms Beyond the Joints
Inflammatory types can also cause tiredness, low-grade fever, weight loss, skin rashes, nail changes or red, painful eyes.
These symptoms do not always mean arthritis. Injury, infection, vitamin deficiency and thyroid problems can cause similar complaints, so a proper check-up is important.
What Causes Arthritis?
There is no single cause of arthritis. Each type has its own causes, and several factors often work together.
Wear and Tear of Cartilage
In osteoarthritis, cartilage slowly thins with age, joint overuse and past injuries.
Immune System Problems
In rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis, the immune system mistakenly attacks healthy joint tissue.
High Uric Acid
In gout, too much uric acid in the blood forms crystals in the joints.
Infection
Bacteria or viruses can enter a joint directly or trigger inflammation after an infection elsewhere in the body.
Genes and Family History
Arthritis can run in families. For example, the HLA-B27 gene is strongly linked to ankylosing spondylitis.
Risk Factors You Can and Cannot Change
Cannot change:
- Age
- Sex (women for RA, men for gout and AS)
- Family history and genes
- Past joint injury
- Having psoriasis (for PsA)
Can change:
- Body weight
- Smoking (raises RA risk)
- Alcohol and diet (gout)
- Physical activity level
- Control of diabetes, blood pressure and kidney health
How Is Arthritis Diagnosed?
No single test diagnoses every type of arthritis. A doctor puts together several pieces of information:
- Your symptoms, how they started and which joints are affected
- Family history and other conditions such as psoriasis or diabetes
- Physical examination of the joints, spine, skin and nails
- Blood tests to look for inflammation, antibodies or high uric acid
- Joint fluid testing, when a swollen joint can be safely drained
- Imaging such as X-ray, ultrasound or MRI
Which Tests May Be Recommended for Arthritis?
Blood tests help doctors find the type of arthritis, rule out other causes and check if treatment is safe. Depending on your symptoms, a doctor may recommend:
ESR and CRP
The ESR test and the C-reactive protein (CRP) test measure inflammation in the body. They are often raised in rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis, and are used to track disease activity.
Rheumatoid Factor (RA Factor)
The RA factor test looks for an antibody found in many people with rheumatoid arthritis. It can also be positive in other conditions and in some healthy people, so it is read together with symptoms.
Anti-CCP Antibody
The anti-CCP test is more specific for rheumatoid arthritis than RA factor. It can turn positive early, sometimes before symptoms begin.
Uric Acid
The uric acid test measures uric acid in the blood. It is used to support a gout diagnosis and to monitor treatment. Uric acid can be normal during a gout attack, so doctors may repeat the test 2 to 4 weeks later. The most reliable way to confirm gout is finding urate crystals in joint fluid.
HLA-B27
The HLA-B27 test checks for a gene linked to ankylosing spondylitis and other spondyloarthritis. A positive result supports the diagnosis when back pain and imaging also fit.
ANA (Antinuclear Antibody)
The ANA test screens for autoimmune diseases such as lupus that can cause joint pain.
CBC
A complete blood count (CBC) can show anaemia, which is common in long-term inflammation, and signs of infection.
Kidney and Liver Function Tests
A kidney function test is important in gout, because kidney health affects uric acid levels and medicine choices. Kidney and liver tests are also used to monitor the safety of some arthritis medicines.
Vitamin D and Calcium
The vitamin D test and serum calcium test help check bone health. Low vitamin D can cause bone and muscle pain that may be mistaken for arthritis.
Imaging
X-rays show joint space narrowing and bone changes. Ultrasound can show inflammation and crystal deposits. MRI can detect early sacroiliac joint inflammation in ankylosing spondylitis.
Not everyone needs every test. The right tests depend on your age, symptoms, medical history and your doctor's assessment.
- Osteoarthritis: Mainly X-ray; blood tests to rule out other types
- Rheumatoid arthritis: RA factor, anti-CCP, ESR, CRP, CBC
- Psoriatic arthritis: ESR, CRP; RA factor and anti-CCP usually negative; X-ray or ultrasound
- Gout: Uric acid, kidney function test, joint fluid crystal test
- Ankylosing spondylitis: HLA-B27, ESR, CRP, MRI of sacroiliac joints
How Is Arthritis Treated?
Most types of arthritis cannot be fully cured, but symptoms can be controlled and joint damage can be slowed or prevented. Treatment depends on the type, how active the disease is and your overall health.
Medicines for Pain and Inflammation
Painkillers and anti-inflammatory medicines can reduce pain and swelling. Steroid tablets or injections may be used for short periods during flare-ups.
Disease-Modifying Medicines
For rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis, a rheumatologist may prescribe medicines that calm the immune system. These include conventional DMARDs and newer biologic or targeted medicines. Regular blood tests are often needed to monitor them.
Gout Treatment
Gout attacks are treated with anti-inflammatory medicines, colchicine or steroids. Long-term, uric acid-lowering medicines keep uric acid below the target set by your doctor, which stops new crystals from forming.
Physiotherapy and Exercise
A physiotherapist can teach exercises that strengthen muscles around the joint, improve flexibility and protect posture. Exercise is a core part of treatment for osteoarthritis and ankylosing spondylitis.
Weight Management
Losing extra weight reduces load on the knees and hips. It also lowers uric acid and improves response to treatment in inflammatory arthritis.
Surgery
When a joint is badly damaged and other treatments no longer help, joint replacement or other surgery may be considered.
Always take arthritis medicines under a doctor's guidance. Do not start, stop or change medicines on your own.
How to Prevent Arthritis or Slow It Down
Not all arthritis can be prevented, especially autoimmune types. But these habits lower your risk and protect your joints:
- Keep a healthy weight. Every extra kilo adds load on the knees and hips.
- Stay active. Walking, swimming, cycling and yoga keep joints flexible and muscles strong.
- Protect your joints. Use proper technique when lifting and avoid repeated strain.
- Do not smoke. Smoking raises the risk of rheumatoid arthritis and makes it more severe.
- Limit alcohol and sugary drinks. This lowers the risk of gout attacks.
- Drink enough water. Good hydration helps the kidneys remove uric acid.
- Eat a balanced diet. Include vegetables, fruits, whole grains, pulses and low-fat dairy.
- Manage other conditions. Keep diabetes, blood pressure and cholesterol under control.
- Get tested early. Regular check-ups catch high uric acid, low vitamin D or inflammation before damage occurs.
Arthritis: Common Myths and Facts
Myth 1: Arthritis Only Affects Older People
Fact: Arthritis can start at any age. Ankylosing spondylitis often begins in the late teens or 20s, and juvenile arthritis affects children.
Myth 2: Joint Pain Is Just a Normal Part of Ageing
Fact: Ongoing joint pain is not normal at any age. It should be checked, because early treatment can prevent permanent damage.
Myth 3: Gout Only Happens to People Who Eat Too Much Meat
Fact: Diet is only one factor. Genes, kidney function, body weight and some medicines also raise uric acid.
Myth 4: Psoriatic Arthritis Is Just a Skin Problem
Fact: Psoriatic arthritis is a joint disease. It can damage joints permanently if it is not treated, even when the skin looks mild.
Myth 5: People With Arthritis Should Avoid Exercise
Fact: The right exercise reduces pain and stiffness. Rest during flare-ups, but staying active is one of the best long-term treatments.
When Should You See a Doctor?
Consider seeing a doctor if you have:
- Joint pain, swelling or stiffness lasting more than 2 weeks
- Morning stiffness lasting more than 30 minutes
- Back pain that is worse with rest and better with movement, especially if you are under 45
- A sudden, very painful, red and swollen joint
- Swollen fingers or toes, or joint pain along with psoriasis
- Joint pain with fever, rash, weight loss or red, painful eyes
Get urgent medical care if a single joint becomes hot, red and swollen with fever. This can be septic arthritis, which needs immediate treatment.
Key Takeaways
- Arthritis is a group of more than 100 joint conditions, not a single disease.
- The main types of arthropathy are degenerative, inflammatory, crystal, infectious and disease-related.
- Gout is caused by high uric acid and usually starts with sudden, severe pain in the big toe.
- Psoriatic arthritis can develop in people with psoriasis and often causes swollen fingers, heel pain and nail changes.
- Ankylosing spondylitis causes long-term back pain in young adults that improves with exercise.
- Blood tests such as ESR, RA factor, anti-CCP, uric acid and HLA-B27 help identify the type.
- Early diagnosis and the right treatment can prevent permanent joint damage.
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References & Citations
World Health Organization (WHO) – Osteoarthritis Fact Sheet
Institute for Health Metrics and Evaluation (IHME) – Global Burden of Gout, 1990–2020 (The Lancet Rheumatology, 2024)
IHME – Global Burden of Osteoarthritis, 1990–2020