Which Joints Are Most Affected by Arthritis?

Like many diseases, arthritis is not a one-size-fits-all illness. To explain it in the easiest way—or in the most general terms—think of arthritis in two overarching categories. "As a broad classification, you have inflammatory versus non-inflammatory arthritis," explains Dr. Natalie Azar, rheumatologist and clinical assistant professor in the department of medicine at NYU Langone Health. "We don't categorize arthritis by the joints affected, but by inflammatory versus non-inflammatory." Osteoarthritis—the non-inflammatory kind—is synonymous with wear and tear. (It's generally the kind that occurs as you get older.) Rheumatoid arthritis—the inflammatory kind—is systemic and associated with autoimmune diseases.

Witthaya Prasongsin/Getty

Osteoarthritis most commonly affects the knees ("Think of how many people get knee replacements," Dr. Azar says), as well as the hips and hands. While it is genetic, and can be associated with trauma, like fractures. Obesity can also lead to osteoarthritis, since you're putting too much pressure on your joints, Dr. Azar explains. For people afflicted with osteoarthritis, there unfortunately aren't any FDA-approved medicines that can change the course of the disease. "We're still left treating symptoms," Dr. Azar says. Physical therapy can help strengthen joints—and taking Tylenol to ease pain and inflammation can offer short-term, immediate relief to those dealing with both types of arthritis.

Related: These Are the Best Supplements for People Living with Arthritis

Rheumatoid arthritis, on the other hand, can affect small or large joints—typically four or more. "It's symmetrical, so both sides of the body are involved," Dr. Azar says. "It's not just one knee, but both knees, or both wrists, or both joints of the hands. It's also associated with swelling, stiffness that lasts for more than an hour, and pain." Rheumatoid arthritis, she says, can also affect the kidney and lungs—it's not just a joint disease. Fortunately, with rheumatoid arthritis, there are disease-modifying therapies (or anti-rheumatic drugs) that patients can take in order to put them into remission and reverse damage, Dr. Azar explains.

And while diet doesn't cause either type of arthritis, once you have it (regardless of type), eating an inflammatory diet can exacerbate the situation, Azar says; alcohol, processed sugars, and trans fats are the usual culprits. Following an anti-inflammatory diet full of fruits, vegetables, lean protein, and healthy fats may help boost the immune system, fight inflammation, and strengthen bones, the Arthritis Foundation says. Azar refers patients to the site for information and health tips on what to eat while living with arthritis, but she adds that the diet—like the disease—is not one-size-fits all. Some people can't tolerate nightshade vegetables like tomatoes, eggplants, and potatoes, for example, so you just have to experiment and tailor your diet to see what makes you feel your best.