Question: I've read a lot about rheumatoid arthritis but not osteoarthritis. Is there even a difference between the two?
— Sikeston, MO

Answer: It's somewhat easy to understand why patients connect rheumatoid arthritis (RA) with osteoarthritis (OA) because both conditions are forms of arthritis. "Arthritis" is a general term that encompasses more than 100 rheumatoid disorders. And while rheumatoid arthritis and osteoarthritis both fall under that umbrella, they are significantly different.

What Characterizes Rheumatoid Arthritis?
First and foremost, rheumatoid arthritis is an autoimmune disease. This type of disorder occurs when your body's immune system turns against itself—attacking your body's healthy tissues when it should be protecting them.

Rheumatoid arthritis is a chronic inflammatory form of arthritis that commonly impacts the small joints of the hands and feet. In the spine, it typically affects the cervical (neck) region and various facet joints.

Your joints are covered with a membrane called the synovium. If you have rheumatoid arthritis, your white blood cells (which, under normal circumstances, protect you) attack the synovial membrane. This causes painful, crippling inflammation. Eventually, the synovium thickens, resulting in a new, damaged "covering" on your joints. In turn, your joints lose their normal ability to function. To learn more about this process, read this article about the causes of rheumatoid arthritis.

While we don't know the exact cause of RA, we understand that it may be connected to rheumatoid factor—antibodies (or proteins produced by your body's immune system) that can be detected in your blood. Everyone has some degree of rheumatoid factor, but if you have higher than normal levels of the marker, then your immune system may be affected. However, rheumatoid factor does not guarantee the presence of RA; it's not a flawless measure of detecting the disease.

What Characterizes Osteoarthritis?
Osteoarthritis is far more common—and generally less debilitating—than rheumatoid arthritis. Whereas RA typically affects the cervical spine, OA may affect all regions of the spine—cervical, thoracic (mid-back), and lumbar (low back).

Unlike RA, osteoarthritis is not really a disease. It is caused by the natural aging process, and you may have heard it called degenerative joint disease or spondylosis.

In essence, OA is caused by aging. For instance, when an elderly patient develops a swollen, painful joint that causes compression on the spinal cord, we call that osteoarthritis. But some people have osteoarthritis to a more accelerated degree than others. That's natural, really, because we all age at different rates.

There are a number of specific age-related conditions that can cause osteoarthritis. These include herniated discs and lumbar or cervical spinal stenosis.

Osteoarthritis is characterized by the breakdown of cartilage, which cushions your joints. When your cartilage begins to wear away, you lose that barrier between the bones of your joints. So your bones then can rub onto one another, which can be very painful.

An easy way to think of the main difference between RA and OA is this: rheumatoid arthritis is about inflammation of the tissue around the joints—osteoarthritis is about deterioration of the cartilage between the joints. Of course, there are other differences between rheumatoid arthritis and osteoarthritis. For instance, they have their own unique symptoms and are treated differently. But rheumatoid arthritis and osteoarthritis share one big similarity: they can both impact your spine.