How Are Rheumatoid Arthritis and Osteoarthritis Different?

“Arthritis” is an umbrella term used to describe inflammation of the joints. However, there are different kinds of arthritis, including rheumatoid arthritis (RA) and osteoarthritis (OA).

Although RA and OA both affect your joints, they’re very different forms of arthritis.

RA is an autoimmune disorder that occurs when your immune system attacks the tissues lining your joints.

OA is primarily a degenerative joint disorder caused by wear and tear on your cartilage.

More than 32.5 million people in the United States have OA, while about 1.5 million people have RA.

RA is an autoimmune disorder, which means your body begins to attack itself. If you have RA, your body interprets the soft lining around your joints as a threat, similar to a virus or bacteria, and attacks it.

This attack causes fluid to accumulate within your joint, which is produced by the inflamed tissue. The swelling and fluid buildup also causes:

• pain
• stiffness
• inflammation around your joints
• decrease joint flexibility

OA, the most common form of arthritis, is primarily a degenerative joint disorder. People with OA experience a breakdown of the cartilage that cushions their joints. The wearing down of cartilage causes the bones to rub against each other. This exposes small nerves, causing pain.

OA doesn’t involve an autoimmune process like RA does, but mild inflammation also occurs.

“Fatigue was my first major symptom. They did all sorts of tests, including testing my thyroid. Then, they suggested an HIV test. When joint pain started, they thought it was a blood clot in my knee. Finally, I was referred to a rheumatologist.” —Anonymous, living with rheumatoid arthritis

Both types of arthritis are more common in women than in men. RA and OA are more common in older adults, but RA can develop at any age.

RA can run in families. You have a higher chance of developing the condition if a parent, child, or sibling has it.

You’re more likely to develop OA if you have:

• overweight or obesity
• joint deformities
• diabetes
• gout
• experienced traumatic injuries to your joints

Many of the basic symptoms of RA and OA are the same, including:

• painful, stiff joints
• limited range of motion
• warmth or tenderness in the affected area
• increased intensity of symptoms first thing in the morning

Characteristics of RA

Each kind of arthritis also has its own unique set of symptoms. RA is a systemic disease, which means it can affect your entire body — lungs, heart, eyes — and not just your joints. Early signs of RA can include:

• low-grade fever, especially in children
• muscle aches
• excessive fatigue

People with advanced stages of RA may notice hard lumps underneath the skin near joints. The lumps, called rheumatoid nodules, can be tender.

Characteristics of OA

People with OA are unlikely to experience systemic symptoms. The degenerative nature of OA is limited solely to the joints.

You might develop lumps under the skin around joints, but these lumps are different from rheumatoid nodules. People with OA tend to develop bone spurs, or excess bone growth at the edges of the affected joints. Learn more about the symptoms of OA.

RA and OA may affect different joints.

Affected joints in RA

RA usually begins in the smaller joints. You’re likely to have pain, stiffness, and swelling in the finger joints. As RA progresses, symptoms can develop in larger joints such as knees, shoulders, and ankles.

RA is a symmetrical disease. That means you’ll experience symptoms on both sides of your body at the same time.

Affected joints in OA

OA is less symmetrical. You might have pain in both your left and right knee, for example, but one side or one joint is worse.

OA, like RA, is common in the hand and fingers. OA often affects the spine and hips in addition to the knees.

The primary goal in treating both OA and RA is to:

• reduce pain
• improve function
• minimize damage to your joints

Your doctor will approach these goals differently, depending on which condition you have.

Anti-inflammatory and corticosteroid medications are generally effective for both OA and RA, but use of corticosteroids is minimized.

If you have RA, drugs that suppress your immune system can prevent damage by stopping your body from attacking your joints, and prevent joint damage.

The following are some of the questions you may have about RA and OA:

Can you have both RA and OA?

Yes, it’s possible to have both RA and OA.

While OA usually develops after years of wear and tear on cartilage, people with RA may have it earlier in life due to causes such as sports injuries that result in damage to the cartilage, joints, or ligaments.

People with RA may also develop OA as they get older.

People older than 65 who may have OA can also develop a condition called elderly-onset RA (EORA). Unlike RA, EORA more frequently affects large joints.

Which is more painful?

Arthritis pain varies in intensity among people who have it.

People with either OA or RA may have pain that’s mild to severe, and difficulty moving affected joints.

While people with OA may have morning stiffness that lasts fewer than 30 minutes, it lasts longer for people with RA.

RA may also cause other uncomfortable symptoms such as fever and fatigue.

Although they’re different forms of arthritis, both RA and OA affect your joints. Treatments are available to help reduce the symptoms of both conditions.

Contact your doctor if you think you’re experiencing symptoms of RA or OA. If needed, they can refer you to a specialist who can help you find the right treatment to manage your condition.