RA vs OA

Rheumatoid Arthritis vs. Osteoarthritis

As explained on the "What is RA" page, RA is a systemic disease that affects the entire body. It is characterized by the inflammation of the membrane lining the joint, which causes pain, stiffness, warmth, redness and swelling. The inflamed joint lining, the synovium, can invade and damage bone and cartilage. Inflammatory cells release enzymes that may digest bone and cartilage. The involved joint can lose its shape and alignment, resulting in pain and loss of movement.

Osteoarthritis (OS-tee-oh-are-THRY-tis) (OA), or degenerative joint disease, is one of the oldest and most common types of arthritis. It is characterized by the breakdown of the joint's cartilage. Cartilage is the part of the joint that cushions the ends of bones. Cartilage breakdown causes bones to rub against each other, causing pain and loss of movement.

It affects hands and weight-bearing joints such as knees, hips, feet and the back.

There are many factors that can cause OA. Although age is a risk factor, research has shown that OA is not an inevitable part of aging. Obesity may lead to osteoarthritis of the knees. In addition, people with joint injuries due to sports, work-related activity or accidents may be at increased risk of developing OA.

Genetics has a role in the development of OA, particularly in the hands. Some people may be born with defective cartilage or with slight defects in the way that joints fit together. As a person ages, these defects may cause early cartilage breakdown in the joint. In the process of cartilage breakdown, there may be some inflammation, with enzymes released and more cartilage damage.