The Two Main Types of Arthritis Have Different Causes

Osteoarthritis happens when the cartilage that cushions your joints wears down over time. This is the most common type. It develops slowly, usually after years of use, and is more likely as you age. Your joints have less cushioning, so bone rubs against bone, causing pain and stiffness.

Rheumatoid arthritis is different — it is an autoimmune disease, meaning your immune system attacks the lining of your joints by mistake. This causes inflammation, swelling, and joint damage. It can start suddenly and often affects multiple joints at once, usually on both sides of your body.

A few other types exist — gout (caused by uric acid crystals), lupus-related arthritis, and psoriatic arthritis — but osteoarthritis and rheumatoid arthritis account for most cases. The cause matters because the treatment is different for each.

Key Takeaways

  • Osteoarthritis develops from wear and tear on joints over decades, and age, weight, and past injuries all raise your risk.
  • Rheumatoid arthritis is an autoimmune condition where your immune system mistakenly attacks joint linings, and it can run in families.
  • Injury to a joint — even years earlier — can lead to arthritis in that specific spot later on.
  • Some jobs and sports that repeat the same joint movements increase the chance of osteoarthritis in those joints.
  • Genetics play a role in both types, but environment and lifestyle choices matter too.

Age and Wear-and-Tear in Osteoarthritis

Osteoarthritis is largely a result of time and use. Your cartilage is not designed to last forever. As you move through decades, the cartilage gradually thins and cracks. Once it starts to break down, your body cannot repair it as well as it once did. This is why osteoarthritis is far more common after age 50, though it can start earlier.

The more you use a joint, the more wear it experiences. This does not mean exercise is bad — movement keeps joints healthy. But repetitive stress on the same joint, especially at high intensity or with poor form, speeds up wear. People who did heavy labor for decades, or who played high-impact sports, often develop osteoarthritis in those specific joints first.

Weight, Injury, and Other Risk Factors for Osteoarthritis

Carrying extra weight puts more load on weight-bearing joints like your knees, hips, and lower back. The more weight a joint supports, the faster the cartilage wears. Losing even 10 pounds can reduce stress on these joints and slow progression.

An old injury — even one from years ago — can trigger arthritis in that joint later. If you tore cartilage, broke a bone, or severely sprained an ankle or knee, that joint is at higher risk. The damage may not show up as arthritis for 10 or 20 years, but the injury set the stage.

Muscle weakness also matters. Strong muscles around a joint absorb shock and keep the joint stable. If those muscles weaken — from inactivity, age, or injury — the joint bears more stress. This is why physical activity and strength work can slow osteoarthritis progression.

Genetics and Family History in Rheumatoid Arthritis

Rheumatoid arthritis runs in families. If your parent or sibling has it, your risk is higher. Certain genes make your immune system more likely to attack joint linings. However, having the gene does not mean you will definitely develop the disease — environment and other factors matter too.

Women are two to three times more likely to develop rheumatoid arthritis than men. Hormones may play a role, since the disease often starts or worsens after pregnancy or during menopause. Smoking also raises the risk, especially in people who carry the genetic markers.

Unlike osteoarthritis, rheumatoid arthritis can appear suddenly and at any age, even in younger people. It is not caused by wear and tear, so staying active does not prevent it the way it can help with osteoarthritis.

Infections and Other Causes

Some infections can trigger arthritis. Lyme disease, caused by tick bites, can lead to joint pain and swelling. Hepatitis C and HIV can also cause arthritis-like symptoms. Usually the arthritis goes away once the infection is treated, but sometimes it lingers.

Gout is caused by uric acid crystals building up in joints, usually the big toe. It is linked to diet (especially foods high in purines like red meat and alcohol), genetics, and kidney function. Psoriatic arthritis develops in some people with psoriasis, a skin condition. Lupus, an autoimmune disease, can also cause joint inflammation.

What You Cannot Change and What You Can

You cannot change your age or your genes. If arthritis runs in your family, you have a higher baseline risk. But that does not mean you will develop it, and it does not mean you are powerless.

You can manage your weight, stay physically active, and protect your joints from injury. If you have a job or hobby that stresses certain joints, you can use proper technique, take breaks, and wear protective gear. If you smoke and have a family history of rheumatoid arthritis, quitting reduces your risk. These changes will not erase genetic risk, but they can delay onset or reduce severity.

If you already have arthritis, understanding what caused it helps you and your doctor decide on treatment and what to do next. Osteoarthritis and rheumatoid arthritis respond to different approaches, so knowing which one you have matters.

Frequently Asked Questions

Can arthritis be caused by cold weather?

Cold does not cause arthritis, but people with existing arthritis often notice more pain and stiffness in cold weather. This may be because cold air causes tissues to contract slightly, or because barometric pressure changes affect joint fluid. The arthritis itself was caused by something else — the cold just makes symptoms more noticeable.

Does exercise cause osteoarthritis?

Regular moderate exercise does not cause osteoarthritis and may help prevent it by keeping muscles strong and joints mobile. However, intense repetitive stress on the same joint — like running marathons or doing the same heavy labor for decades — can speed up wear. The key is variety and balance, not avoiding movement.

If my parent has rheumatoid arthritis, will I definitely get it?

No. Having a parent with rheumatoid arthritis raises your risk, but most people with a family history never develop it. Genes load the gun, but environment pulls the trigger. Smoking, infections, and stress may play a role in whether someone with genetic risk actually develops the disease.

Can arthritis be caused by stress?

Stress does not directly cause arthritis, but it may worsen inflammation in people who already have rheumatoid arthritis. Stress can also make pain feel worse and reduce your ability to stay active, which indirectly affects joint health. Managing stress is helpful for overall health, but it is not a cause of arthritis itself.