Osteoarthritis is the most common type of arthritis by a wide margin. Among U.S. adults diagnosed with arthritis, osteoarthritis accounts for nearly half of all cases, affecting an estimated 33.2 million people. The next most common type, rheumatoid arthritis, affects about 10.6 million, roughly a third as many.
How Osteoarthritis Differs From Other Types
There are more than 100 types of arthritis, but most fall into two broad categories: degenerative and inflammatory. Osteoarthritis is degenerative. It develops when the protective cartilage that cushions the ends of your bones gradually breaks down over time, leading to pain, stiffness, and reduced range of motion. The bone underneath the cartilage thickens, and small bony growths called bone spurs can form around the joint.
Rheumatoid arthritis, the second most common type at about 15.8% of arthritis cases, works differently. It’s an autoimmune condition where the immune system attacks the lining of the joints, causing inflammation that can eventually damage cartilage and bone. Psoriatic arthritis, the third most common subtype, affects about 1 million Americans and is linked to the skin condition psoriasis. Gout, another well-known form, results from uric acid crystals building up in a joint.
The distinction matters because the cause shapes the treatment. Osteoarthritis is primarily a mechanical, wear-related problem. Rheumatoid arthritis and psoriatic arthritis require treatments that calm the immune system. Osteoarthritis treatments focus on protecting the joint, managing pain, and maintaining mobility.
Which Joints It Affects
Osteoarthritis can damage any joint, but it most commonly affects the knees, hips, hands, and spine. Knees bear an enormous share of your body weight with every step, making them especially vulnerable. The small joints of the fingers and the base of the thumb are also frequent sites, which is why many people first notice osteoarthritis when gripping or twisting becomes painful. Hip osteoarthritis tends to cause deep, aching pain in the groin or outer thigh, and spinal osteoarthritis typically affects the lower back or neck.
Unlike rheumatoid arthritis, which often strikes symmetrically (both wrists, both knees), osteoarthritis can develop in just one joint, particularly if that joint has a history of injury or heavy use.
What It Feels Like
The hallmark of osteoarthritis is pain that worsens with activity and improves with rest, at least in the early stages. You might notice stiffness when you first wake up or after sitting for a long time, but it typically loosens within 15 to 30 minutes. That’s a useful clue: morning stiffness lasting more than an hour points more toward rheumatoid arthritis.
As the condition progresses, the joint may feel stiff more consistently, swell after use, or make a grinding or crackling sensation during movement. Some people eventually lose flexibility and find that the joint no longer moves through its full range. In advanced cases, the joint can become visibly enlarged or misaligned, especially in the fingers.
Who Gets Osteoarthritis
Age is the single biggest risk factor. Arthritis can develop at any age, but the likelihood climbs steadily as you get older, simply because joints accumulate more wear over time and cartilage becomes less resilient. Most people diagnosed with osteoarthritis are over 50, and it’s far more common in women than men after age 55.
Carrying extra weight significantly increases the risk, especially for knee osteoarthritis. Every pound of body weight translates to roughly three to four pounds of force on the knee joint during walking, so even modest weight gain adds up over years. Previous joint injuries also raise the odds. A torn ligament, a fractured bone near a joint, or repetitive stress from certain jobs or sports can set the stage for osteoarthritis years or even decades later. Genetics play a role too: if your parents had osteoarthritis, particularly in the hands, your risk is higher.
How Osteoarthritis Is Managed
There is no way to reverse cartilage loss once it has occurred, so management focuses on slowing the progression, reducing pain, and keeping you active. Current guidelines recommend three core strategies for everyone with osteoarthritis, regardless of age or severity: education about the condition, regular exercise, and weight loss if needed.
Exercise is considered a first-line treatment, not just a supplement to medication. Strengthening the muscles around a joint takes pressure off the cartilage, and low-impact aerobic activity like walking, swimming, or cycling helps maintain flexibility and reduce stiffness. Many people assume that exercise will make things worse, but the evidence consistently shows the opposite. Staying sedentary accelerates joint deterioration.
For pain relief, over-the-counter options like acetaminophen or anti-inflammatory medications are commonly used. Topical creams applied directly to the skin over the joint can help with hand or knee osteoarthritis while minimizing side effects. Physical therapy is often valuable for learning joint-friendly movement patterns and building targeted strength. When conservative approaches stop working and pain or disability becomes severe, joint replacement surgery, particularly for hips and knees, has high success rates and can dramatically restore quality of life.
The Numbers Are Growing
About 53 million U.S. adults currently have some form of arthritis. By 2040, that number is projected to reach 78 million, with an estimated 34.6 million of those people reporting that arthritis limits their daily activities. The increase is driven largely by an aging population and rising rates of obesity, both of which disproportionately fuel osteoarthritis. This trajectory makes osteoarthritis not just the most common type of arthritis today, but the one most likely to affect more people in the coming decades.