Osteoarthritis and Rheumatoid Arthritis: how do they differ?

Osteoarthritis and Rheumatoid Arthritis are both chronic (long term) conditions that can cause painful, inflamed joints.  The two conditions have very different causes, but many of the symptoms are the same as they develop.

Other health problems that can be associated with both conditions include:

• Damaged cartilage
• Fluid build up around the joints
• Pain and reduction of movement in joints
• Swelling and tenderness
• Disfigurement
• Reduced quality of life

Osteoarthritis

Osteoarthritis is a chronic biomechanical (structural) joint condition. It is caused by wear and tear on the cartilage tissue that provides cushioning between the joints. Osteoarthritis  is often related to, but not caused by, aging. Young people do not usually suffer from this: it is most often a condition of the elderly. However, serious trauma due to sport injury or an accident can cause Osteoarthritis in the young.

Osteoarthritis causes a loss of water and proteoglycans (long chains of protein and carbohydrate molecules that give cartilage structure) from joint tissue. This loss can have several effects:

• Cartilage can become thinner, less elastic and more easily torn
• Spaces between joints can narrow
• Bones can rub together and become pitted,  causing friction and even more damage
• Bone spurs may develop, exacerbating the problem
• Joints can become painful and stiff, restricting movement
• Osteoarthritis most commonly affects weight bearing joints such as the knees and hips

Rheumatoid arthritis

Rheumatoid arthritis is an autoimmune condition that causes inflammation and swelling in the joints. “Autoimmune” means the condition is caused by an overactive immune system that mistakes parts of the body as an ‘enemy’, and proceeds to attack healthy tissue. Rheumatoid arthritis primarily affects joints and surrounding tissue, but it can affect organs too. Unlike Osteoarthritis, Rheumatoid arthritis can occur at all ages – for example, children can have Juvenile Rheumatoid Arthritis.

The over active immune response that causes Rheumatoid arthritis can also cause many things to happen:

• Synovial fluid (fluid between joints) can become inflamed
• The body can overproduce synovial fluid, which deforms the joints
• Cartilage can be destroyed
• Movement and stiffness can be restricted (this is often worse just after waking)
• Joints can be painful and swollen

Rheumatoid arthritis most often affects the hands, wrists, ankles and feet.