Osteoarthritis vs rheumatoid arthritis: the key differences

Osteoarthritis is, broadly, a mechanical and repair problem: over time the cartilage cushioning a joint thins and the joint becomes painful and stiff. Rheumatoid arthritis is an immune problem: inflammation is directed at the joint lining by mistake and can affect the rest of the body. Both cause joint pain, swelling and stiffness, which is why they are confused, but they are different diseases with different treatments.

In everyday terms, osteoarthritis tends to start later in life, affect weight-bearing joints and the hands, and get worse with use. Rheumatoid arthritis tends to involve several joints on both sides, cause longer morning stiffness and can make people feel generally unwell. A GP can usually distinguish them from the story and examination, and uses blood tests and referral when rheumatoid arthritis is suspected.

The NHS describes osteoarthritis as a condition that causes joints to become painful and stiff and says it is the most common type of arthritis in the UK. The main symptoms are joint pain and stiffness and problems moving the joint, and some people also have swelling, tenderness and a grating or crackling sound. Severity varies greatly, and for some people symptoms are mild and come and go.

The exact cause is not known, but the NHS lists joint injury, other joint conditions such as rheumatoid arthritis or gout, age, family history, obesity and being a woman as factors that raise risk. A GP may suspect osteoarthritis if you are 45 or older, have joint pain that gets worse the more you use the joint, and have stiffness that is absent in the morning or lasts less than 30 minutes. Arthritis UK adds that a GP can usually diagnose it from your history and examination without further tests unless there is doubt.

The NHS says osteoarthritis cannot be cured but does not necessarily get worse over time and can sometimes improve. Mild symptoms can be managed with regular exercise, losing weight if overweight, suitable footwear and devices that reduce strain on the joint. Painkillers and physiotherapy are used for more severe symptoms, and surgery to repair or replace a joint is done in a small number of cases.

The NHS describes rheumatoid arthritis as a long-term condition that causes pain, swelling and stiffness in the joints, usually in the hands, feet and wrists, with flare-ups. Symptoms often develop gradually over several weeks, though some cases progress over a few days. The joints can become hot and tender to touch, and firm lumps called rheumatoid nodules can develop under the skin. Arthritis UK says around 1 in 5 people develop nodules.

The NHS says it is an autoimmune disease, that it is not clear what triggers the problem, and that you are at increased risk if you are a woman, have a family history of rheumatoid arthritis or smoke. It cannot be cured, but early diagnosis and appropriate treatment enable many people to have months or even years between flares. The main treatments are long-term medicines to relieve symptoms and slow progress, supportive treatments such as physiotherapy and occupational therapy, and surgery to correct joint problems.

Possible complications named by the NHS include carpal tunnel syndrome, inflammation of the lungs, heart and eyes, and an increased risk of heart attack and stroke, which is why good control of the condition is emphasised.

The NHS says there is no definitive test for rheumatoid arthritis, because many conditions cause joint stiffness and inflammation. A GP examines the joints, asks about all symptoms and may arrange blood tests. ESR and CRP measure inflammation, and a full blood count helps rule out other causes and check for anaemia. Rheumatoid factor is found at a high level in more than half of people with rheumatoid arthritis when the disease starts, but about 1 in 20 people without it also test positive. The anti-CCP antibody test is also used. People who test positive for anti-CCP are very likely to develop rheumatoid arthritis, but not everybody with the disease has it. Scans such as X-ray and MRI can show joint inflammation and damage and help tell types of arthritis apart.

For osteoarthritis, the NHS says further tests such as X-rays or blood tests are not usually necessary, but may be used to rule out other causes such as rheumatoid arthritis or a fractured bone. The two conditions can coexist, and osteoarthritis can develop in joints previously damaged by rheumatoid arthritis.

The NHS advises seeing a GP if you have persistent symptoms of osteoarthritis, and if you think you have symptoms of rheumatoid arthritis so they can look for the underlying cause. Prompt assessment is particularly worthwhile for suspected rheumatoid arthritis, because early treatment can reduce the risk of joint damage. A single hot, swollen, very painful joint with fever is a different problem and needs urgent assessment, as infection inside a joint can look similar.