Abstract
It is estimated that 32.5 million US adults have clinical osteoarthritis (OA), with the most common sites being knee and hip. OA is associated with substantial individual and societal costs. Race/ethnicity, socioeconomic status (SES), and geographic variations in the prevalence of knee and hip OA are well established around the world. In addition, clinical outcomes associated with hip and knee OA differ according to race/ethnicity, SES, and geography. This variation is likely multifactorial and may also reflect country-specific differences in health care systems. The interplay between different factors, such as geography, SES, and race/ethnicity, is difficult to study.