Bum Knees Becoming an Epidemic

Sep. 8, 2008 - CHAPEL HILL- Almost half of all U.S. adults and nearly two-thirds of obese adults will develop painful osteoarthritis of the knee by age 85, a study based at UNC suggests.

The study also found that a person's lifetime risk rose as body mass index or BMI increased, with the greatest risk found in those whose weight was normal at age 18 but were overweight or obese at 45 or older.

"These results show how important weight management is for people throughout their lives," said Joanne Jordan, principal investigator of the Johnston County Osteoarthritis Project and senior study author.

"Simply put, people who keep their weight within the normal range are much less likely to develop symptomatic knee osteoarthritis as they get older and thus much less likely to face the need for major surgical procedures, such as knee replacement surgery."

The study also sends an important message to physicians, said Jordan, director of the Thurston Arthritis Research Center and professor of medicine and orthopaedics in the UNC School of Medicine. "They need to include the risk of knee osteoarthritis in the discussion when counseling patients about weight management and they need to factor that risk into their treatment plans."

The results were published in the Sept. 15 issue of Arthritis Care & Research. In the study, researchers collected and analyzed data over a 13-year period from 3,068 men and women 45 years old and older who live in North Carolina's Johnston County.

At two separate points during the study, each participant was interviewed at home and given a clinical exam that included taking X-ray images of their knees and measuring their BMI. They were interviewed a second time two weeks after the clinical exam. In addition, researchers calculated the subjects' BMI at age 18 based on their self report of height and weight at that age.