If you think that arthritis is something only older people get, you're not alone. Many people picture a person with arthritis as an elderly relative with bony, knobby fingers or a hip replacement.
It's true that the most common type of arthritis, osteoarthritis, is a disease that mainly affects people over the age of 50. And it's true that at least half of adults over the age of 64 report having been told by a doctor that they have arthritis.
But there are more than 100 types of arthritis and some of them affect younger adults and children.
Arthritis Is More Than Aches and Pains
The term "arthritis" is often used to describe aches and pains in or around a joint. However, the word actually means joint inflammation. The joint is painful and swollen, and has limited motion. The joint may also appear red when the inflammation is severe.
Some types of joint disease have more inflammation than others. For example, rheumatoid arthritis generally causes noticeable inflammation, while osteoarthritis (also called "degenerative joint disease") usually causes mild inflammation.
People with joint pain could have problems unrelated to arthritis. For example, tendon inflammation (tendonitis) can cause joint pain but the joint itself isn't the problem. To make it even more complicated, people with certain types of arthritis may also have tendonitis. One example is psoriatic arthritis, a type of joint disease that occurs in 10% to 20% of people with the skin condition, psoriasis.
Who Gets Arthritis?
Different types of arthritis tend to affect people in different age groups. For example:
Osteoarthritis (OA) - Although primarily a disease in older adults, younger adults and even kids sometimes develop OA. For example, OA may develop years after an injury such as a fracture near a joint.
Polymyalgia rheumatica (PMR) - This is a type of arthritis affecting the shoulders and hips. It only affects adults ages 50 and older; the typical patient is at least in his or her late 60s.
Rheumatoid Arthritis (RA) - The onset of this disease peaks among adults ages 25 to 50.
Lupus - In this condition the body's immune system mistakenly attacks its own tissues. This causes inflammation in the joints and other organs. Lupus is most commonly diagnosed in women ages 20 to 40.
Gout - This condition commonly causes sudden onset of arthritis in one joint at a time (especially the big toe); it affects men of any age and post-menopausal women.
Arthritis That Is (Almost) Unique to Children
Some types of arthritis primarily affect children. Their names may sound similar — Juvenile Rheumatoid Arthritis (JRA), Juvenile Lupus or, more recently, Juvenile Idiopathic Arthritis (JIA). But they are distinct diseases with important differences from the adults versions.
For example, it's rare that an adult with rheumatoid arthritis has eye inflammation — especially without symptoms — but that's a relatively common problem for kids with JIA. Also, arthritis can cause as much — or even more — trouble for young children as the more common versions do for adults. Recent data suggest that nearly 300,000 kids under age 18 have arthritis or a related condition in this country. This translates to about 4 per 1,000 children and accounts for 827,000 visits to doctors each year. Because children's bones and joints are still developing, and because fitting in is so important to kids, the challenges faced by kids with arthritis are quite different from those of adults.
As odd as it may seem, arthritis that is nearly unique to children can affect adults. One example is a condition called Still's Disease. It is named for George F. Still, a British pediatrician who described it near the turn of the last century. Still's Disease is one of the major types of JIA. Typical symptoms include a rash and fever, which are not common features of adult RA. However, so-called "Adult Onset Still's Disease" affects 1 in 100,000 adults. It can be a severe illness that requires hospitalization and powerful immunosuppressive drugs to control.