RA vs OA vs PsA: Which one is it?

Arthritis is more than one disease. Although all types of arthritis affect your joints, different types have different causes and treatments. Osteoarthritis is caused by wear and tear over time, and called degenerative arthritis. Rheumatoid and psoriatic arthritis are inflammatory types of arthritis caused by your immune system.

There are different treatments and flare triggers for different types of arthritis. You could even have more than one type of arthritis.

To understand how different types of arthritis affect your joints, it’s helpful to know a bit about the anatomy of joints:

• A joint is where two bones come together. The surface of the bones is covered with a smooth tissue called cartilage. Cartilage protects the ends of the bone and helps a joint move freely.
• The inside of a joint is lined by tissue called synovium. Synovium produces fluid to lubricate the joint.
• Joints are supported by tendons and ligaments. Ligaments attach bones to other bones. Tendons attach muscles to the bones of a joint.

Here are the differences between osteoarthritis (OA), rheumatoid arthritis (RA) and psoriatic arthritis (PsA).

Osteoarthritis (OA)

OA is called a degenerative joint disease, which is a medical term for wear and tear. It is the most common type of arthritis. OA is caused by the wear and tear of age, but OA can occur earlier in life if a joint has been injured. In OA, the cartilage covering the bones of the joint wears away. The ends of the bones then grind on each other, causing pain, stiffness and swelling.

Because OA is caused by wear and tear, it commonly occurs in joints that bear weight, such as the joints of your back, hips and knees. OA slowly gets worse over time. It’s often triggered by overactivity or joint trauma, but there are other triggers as well, such as stress and weather changes.

The main symptoms of OA are:

• Pain
• Stiffness
• Limited motion
• Swelling

You may be at higher risk for this type of joint disease if you are older in age, overweight or you have overused or injured a joint. OA is diagnosed by the history of your symptoms and a physical exam, along with X-rays and other imaging studies.

There is no cure for OA, but physical therapy, exercise, weight loss, and over-the-counter and prescription pain medications can help. Surgery, such as a hip or knee replacement, may be needed for some people.

Rheumatoid Arthritis (RA)

RA is a more widespread inflammatory joint disease not caused by wear and tear of specific joints. RA can occur at any age. Like OA, it increases with age, becoming most common around age 60. RA is an immune system disease called an autoimmune disease. This means that your body’s defense system (your immune system) mistakenly attacks your body instead of invaders like germs. The form of the attack is inflammation.

RA attacks more than one joint and attacks on both sides of your body. The most common joints are the joints of your hands, wrists and knees. RA causes inflammation of the joint synovium. Inflammatory chemicals produced by your immune system can attack and destroy joint surfaces.

Symptoms of RA can come and go unpredictably. When symptoms get worse, it is called a flare. When they are quiet, it is called a remission. Common symptoms include:

• Aching pain in more than one joint on both sides of your body
• Stiffness, especially in the morning
• Tender swelling

Because RA attacks other parts of your body besides your joints, you may also have fever, weight loss and fatigue. You may be at higher risk for RA if you have a family history of RA. Women are affected more commonly than men.

RA is diagnosed by the history of your symptoms and a physical exam. Imaging studies are important. Blood tests that look for inflammation and antibodies caused by autoimmune disease are also important for diagnosis.

There is no cure for RA, but drugs that slow inflammation and the progression of RA can help relieve symptoms, as well as slow progression. These drugs are called disease-modifying anti-rheumatic drugs (DMARDs).

Related questions

• How long does a rheumatoid arthritis flare-up last?
• What are the 4 stages of rheumatoid arthritis?
• What are the best foods to eat or avoid for RA?

Psoriatic Arthritis (PsA)

Like RA, PsA is an inflammatory arthritis caused by an autoimmune disease. It usually occurs in people some years after they have been diagnosed with psoriasis, a skin condition. However, in a small number of people, psoriasis comes after PsA. About 30 percent of people with psoriasis develop PsA.

PsA attacks joints in the same way RA does. Unlike RA, PsA also causes inflammation where tendons and ligaments attach to bones, especially in the heel, bottom of the foot and lower back. PsA can attack one or more joints. The most common joints are knees, ankles, fingers and toes. Common symptoms are:

• Stiff, swollen and painful joints
• Joints that are tender and warm to touch
• Painful heels and feet
• Lower back pain
• Swollen fingers and toes
• Pitted nails
• Itchy, painful, red skin patches

PsA can occur at any age. The most common age range is 30 to 55. Men and women are equally affected. Diagnosis of PsA is by the history of your symptoms, blood tests and imaging studies of your joints.

Like the other types of arthritis, there is no cure for PsA. Treatment of PsA is similar to RA, which involves the use of DMARDs to relieve symptoms and slow the progression of the disease.