What's the difference between osteoarthritis and rheumatoid arthritis?

Forms of arthritis

Around 10 million UK adults are limited by the effects of arthritis in their day-to-day lives¹. Arthritis means inflammation of a joint. Your joints allow movement where two bones meet - including your fingers, elbows, knees, and hips - and so arthritis affects how you move, alongside other symptoms.

With more than 100 types of arthritis in existence, knowing how to spot the difference can help get you the right diagnosis and treatment.

The most common types of arthritis are:

• Osteoarthritis (OA).

• Rheumatoid arthritis (RA).

• Septic arthritis.

• Gout.

• Psoriatic arthritis (PsA).

Rheumatoid arthritis (RA) and Osteoarthritis (OA) are the two most common forms of arthritis². However, osteoarthritis is the most common by a long way, affecting around ten times as many people as rheumatoid arthritis.

The difference between osteoarthritis and rheumatoid arthritis

OA and RA may both cause joint pain, but they have many different characteristics. Here's how to tell them apart.

What's the cause?

OA: caused by wear and tear of joints.

The joining bones in your joints are coated in protective cartilage and a fluid called synovium which allows these bones to move together. In osteoarthritis, the movement between your bones wears these substances down over time. This gradually makes joints more painful and difficult to move.

RA: when your immune system attacks healthy tissue in your joints.

Your immune system mistakenly attacks the healthy synovium fluid that coats your joints. This causes inflammation in your joints, which can eventually lead to permanent damage, pain, and difficulty with movement.

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Bones, joints and muscles

Gout diet: foods to eat and avoid

Gout is a type of arthritis, typically caused by a build-up of uric acid in the blood. When uric acid levels build up, it can cause crystals of uric acid to be formed, which deposit in joints and cause irritation, inflammation and swelling. This is known as a gout attack, which can be very painful. High levels of uric acid in the blood could be due to several reasons. It may be a result of the kidney's reduced ability to clear the uric acid. It may be an overproduction of compounds that break down uric acid (purines). It may be a combination of both.

by Victoria Raw

Bones, joints and muscles

Gout

Gout causes attacks of pain and swelling in one or more joints. An anti-inflammatory painkiller usually eases an attack quickly. Lifestyle factors may reduce the risk of having gout attacks. These include losing weight (if overweight), eating a healthy diet and not drinking a lot of alcohol or sugar-sweetened soft drinks. If gout attacks are frequent then taking a medicine (such as allopurinol) each day can prevent them.

by Dr Hayley Willacy, FRCGP

Where in the body?

OA: usually affects one set of joints. It often begins on one side of your body but can spread to the other side. Osteoarthritis can affect any of your joints, but is most common in the ones that get used the most, such as your:

• Knees.

• Hips.

• Hands.

• Fingers and thumbs.

• Lower spine.

RA: usually affects joints that are parallel on both sides of your body and the smaller joints, such as those in your hands or your feet. Like osteoarthritis, any joint can be affected, but rheumatoid arthritis is most common in your:

• Fingers and thumbs.

• Wrists.

• Ankles.

• Feet.

RA may also affect your internal organs, including your:

• Heart.

• Liver.

• Eyes.

What are the symptoms?

Symptoms in your joints:

In osteoarthritis, there are no other symptoms outside of the joints. However, with rheumatoid arthritis, you may also experience other symptoms, including:

• Small painless lumps - usually over your forearms and elbows.

• Feeling tired all the time.

• A general feeling of being ill.

• A high temperature (fever).

• Unexplained weight loss.

• Muscle aches and pains.

What genetic and environmental factors?

OA is linked to:

• Joint injury or overuse.

• Age - most often develops in people over 50 years old, although secondary osteoarthritis, which is brought on by injury or damage, can occur in younger people.

• Sex - women are more likely to develop OA than men.

• Body weight - excess weight puts more stress on your joints, especially weight-bearing joints like your knees and hips.

• Genetics - having a family history of OA may make it more likely to develop it, although the risk is low.

RA is linked to:

• Never giving birth or never breastfeeding - puts women at greater risk than women who have.

• Smoking.

• Age - most often develops in people between 30 and 50 years old, but can affect people at any age.

• Sex - women are more likely to develop RA than men.

• Body weight - being obese increases your risk of RA.

• Genetics - there's evidence that RA can run in families.

How is it managed?

There is no cure for osteoarthritis or rheumatoid arthritis, so treatment for both aims to ease symptoms, make daily life more manageable, and prevent further joint damage where possible.

OA: Several lifestyle changes and therapies can help to improve symptoms. These include: regular physical activity that's gentle on joints, muscle-strengthening exercises to support joints, healthy weight loss, physiotherapy, prescription medications, over-the-counter pain relief drugs, and supportive equipment such as canes or crutches. If these treatments don’t make enough of a difference, your doctor may recommend surgery to replace your joints with artificial ones.

RA: special medications - called disease-modifying antirheumatic drugs (DMARDs) and biological response modifiers - may help slow the disease and prevent further joint damage. In addition to these drugs, people with rheumatoid arthritis can also self-manage their symptoms using many of the same therapies for osteoarthritis. Of these, healthy weight loss and regular, joint-protecting exercise are the most important.

Further reading

1. Arthritis Action: What is arthritis.

2. Centers for Disease Control and Prevention: Arthritis types.