Osteoarthritis and rheumatoid arthritis are both forms of arthritis, and can cause joint tenderness and deformity. This is where their similarity stops, as they are actually very different diseases.
Osteoarthritis is a form of mechanical arthritis. It is caused by wear and tear of the cartilage and joint, much like the tires of a car. The more we use our joints, in activities like sports or repetitive movements, the more likely we are to get osteoarthritis.
Osteoarthritis is very common, and its prevalence increases as we get older. In fact, 35% of people over 65 and 80% of people over 75 have at least one arthritic joint.
Osteoarthritis can affect any joint, but it’s mostly seen in large joints like hips and knees. The arthritis pain is usually worse at the end of the day or after a lot of activity. Stiffness in the morning lasts a few minutes.
Rheumatoid arthritis is caused by an overactive immune system. The immune system actually attacks the joint, causing a lot of inflammation which can actually dissolve pieces of the bone. I sometimes think of this as pacman eating away at a joint. It can start at any age. Its prevalence is about 1% in the United States.
Rheumatoid arthritis most commonly affects small joints of hands and feet, but like osteoarthritis, can go to any joint. The pain is usually worse in the morning and after periods of inactivity. Morning stiffness commonly lasts several hours. Pain and stiffness get better as the day progresses.
Here are the differences between the two diseases at a glance:
|Cause||Wear and tear||Autoimmune|
|Prevalence||Increases with age||About 1% of population|
|Gender||Women > Men||Women > Men|
|Joint size||Usually large joints||Usually small joints|
|Inflammation||Usually little||Usually a lot|
|Timing||Pain worse at night||Pain worse in morning|
|Morning stiffness||Less than an hour||More than an hour|
Unfortunately, most arthritis is not this simple. For example, you can have osteoarthritis affecting small joints of the hands, or rheumatoid arthritis with not a lot of inflammation. Or you may have one of more than 100 other types of arthritis. The diagnosis will require a trained physician. If you have arthritis pain, it is a good idea to talk to your physician or see a rheumatologist.