The prevalence of symptomatic knee osteoarthritis (OA) has been increasing over the past several decades in the United States concurrent with an aging population and the growing obesity epidemic. We quantify the impact of these factors on the number of persons with symptomatic knee OA in the first decades of 21st century.
We calculated prevalence of clinically diagnosed symptomatic knee OA from the National Health Interview Survey 2007–08 and derived the proportion with advanced disease (Kellgren-Lawrence grades 3–4) using the Osteoarthritis Policy Model, a validated simulation model of knee OA. Incorporating contemporary obesity rates and population estimates, we calculated the number of persons living with symptomatic knee OA.
We estimate that about fourteen million persons had symptomatic knee OA, with advanced OA comprising over half of those cases. This includes over three million African American, Hispanic, and other racial/ethnic minorities. Adults under 45 years of age represented nearly two million cases of symptomatic knee OA and individuals between 45 and 65 years of age six million more.
Over half of all persons with symptomatic knee OA are younger than 65 years of age. As many of these younger persons will live for three decades or more, there is substantially more time for greater disability to occur and policymakers should anticipate healthcare utilization for knee OA to increase further in upcoming decades. These data emphasize the need for the deployment of innovative prevention and treatment strategies for knee OA, especially among younger persons.