A landmark government study suggests nearly one in two people (46 percent) will develop painful knee osteoarthritis over their lifetime, with the highest risk among those who are obese. According to the Arthritis Foundation, the study underscores the immediate need for the public to understand what they can do to reduce the tremendous pain, disability and cost associated with arthritis.

Arthritis is exploding in an aging population of U.S. baby boomers. Nearly one in five U.S. adults (46 million people) has arthritis and an estimated 67 million people will be affected by 2030. Osteoarthritis, the most common type of arthritis, currently affects more than 27 million people in the U.S.

The study, published in the September issue of Arthritis Care & Research, was conducted using data from the Thurston Arthritis Research Center, University of North Carolina-based Johnston County Osteoarthritis Project. It is one of the largest longitudinal studies to monitor the onset and progression of knee and hip osteoarthritis in this country. While there were no significant differences in risk by sex, race and education, the study found that nearly two in three people (65 percent) who are obese will develop knee osteoarthritis over their lifetime. The study also found that those with a prior knee injury had a lifetime risk of 57 percent.

“This groundbreaking research reaffirms the importance and need for Americans to take action to prevent the problems that knee osteoarthritis can cause and to reduce its occurrence,” said Janet Collins Ph.D., director of the Centers for Disease Control and Prevention’s National Center for Chronic Disease Prevention and Health Promotion. “CDC’s Arthritis Program works in partnership with states and national organizations to promote arthritis self-management education and physical activity that help people with arthritis improve the quality of their lives.”

Most Americans are unaware of the seriousness of arthritis and the impact it can have on their lives. Arthritis is the nation’s most common cause of disability and costs the U.S. economy more than $128 billion annually. Knee osteoarthritis, the most frequent form of lower extremity arthritis, contributes to 418,000 knee replacement procedures annually and in 2006 accounted for 496,000 hospital discharges and $19 billion in hospital charges.

“While Americans are looking forward to longer life expectancies than ever before, the reality is that they will also be facing many more years of pain and disability,” said Dr. John H. Klippel, president and CEO of the Arthritis Foundation. “Obesity in this country is at an all-time high, putting millions at risk for disabling arthritis. Coupled with sedentary lifestyles and an aging baby boomer population, we are facing a public health crisis if Americans and Congress don’t take action.

“People need to know there are things they can do now to help themselves. These actions will limit the impact of arthritis for both individuals and society as a whole,” said Dr. Patience H. White, chief public health officer of the Arthritis Foundation. For information on how to get started, visit http://www.arthritis.org/prevent-osteoarthritis.php.