The diagnosis of knee osteoarthritis (OA) will rise sharply among Americans between the ages of 35 and 84 in the next 10 years, according to research presented in November by the American College of Rheumatology.

 

Based on current trends, nearly 6.5 million individuals in this age group will get the diagnosis, with people as young as 45 to 64 years old accounting for more than half of newly diagnosed cases.

 

These data, the researchers said, portend a need for total knee replacements down the road and, therefore, pose an additional burden on the United States health care system.

 

Elena Losina, PhD, co-director of the Orthopedics and Arthritis Center for Outcomes Research at the Brigham and Women’s Hospital, Boston, and lead investigator of the study, noted that the data are consistent with the recently observed tripling of total knee replacement use in 45- to 65-year-old persons in the United States.

 

Researchers used data from the Centers for Disease Control in a validated computer model of the course of knee OA to estimate the number of newly diagnosed cases in the United States during two decades: the 1990s and the 2010s. The researchers found that physician-diagnosed knee OA affects about 7 percent of Americans over the age of 45. They estimate that Americans will be diagnosed with knee OA much earlier in life in the 2010s versus the 1990s.

 

In fact, the average age of physician-diagnosed knee OA is projected to fall from age 72 in the 1990s to age 56 in the 2010s—a difference of 16 years. Additionally, they found that Americans who are between the ages of 35 and 84 in the early 2010s are likely to account for nearly 6.5 million new cases of knee OA over the next decade, with ages 45 to 64 accounting for 59 percent of them.

 

The data also mean that about 5 percent of all Americans ages 45 to 54 will be diagnosed with knee OA over the next decade of their life, compared with only 1.5 percent based on the data from the 1990s.

 

Losina noted that in the past decade, obesity and knee injuries have become more prevalent, possibly contributing to the increase in knee OA in younger adults.

—Meg LaPorte