I saw a report put out by the U.S. Census Bureau that there will be 400 million people in the United States by the year 2043. And that of the 78 million baby boomers (I am one!), half will have osteoarthritis. This makes me wonder how come half get arthritis and half don’t. Which half am I in?

Osteoarthritis is a potentially disabling condition typically affecting the large joints (e.g., hips, knees, ankles). Areas of the protective cartilage wear down to the bone and then destructive changes in the bone occur. The soft tissues around the joint (called the capsule) get thicker and stiffer. The result can be pain, stiffness, loss of motion, loss of function, and disability.

The surprising thing about osteoarthritis is that there can be evidence of severe disease (as seen on X-rays or other imaging studies) without any symptoms. And other people with mild disease can have severe symptoms. Reasons for the differences remain unknown. Likewise, all the reasons why someone develops osteoarthritis while someone else of the same age, size, and demographics does not have not been fully discovered.

We do know there are some risk factors for osteoarthritis. Obesity is the number one risk factor for osteoarthritis of the hip and knee. A full one-third of the baby boomers are considered obese. The number of people who are obese has increased (more than doubled) in the last 25 years. Predictions are that this won’t change any time soon. In fact the trend is going in the opposite direction (i.e., getting worse).

High-impact and high-intensity physical activities (related to recreation, sports, or occupation) is another risk factor for the development of osteoarthritis of the hips and knees. And a third known risk factor involves structural (anatomic) abnormalities. The most common of these is a condition known as femoroacetabular impingement (FAI).

With FAI, the shape of the hip (from birth) puts the person at increased risk for degenerative disease later in life. Studies are underway to identify other risk factors and to predict who will develop arthritis. The next step in research is to determine how to prevent osteoarthritis from happening. With proper weight management and appropriate exercise this upward trend of osteoarthritis (with or without the impingement problem) may be slowed or possibly even halted.