The epidemiology of knee osteoarthritis: results from the Framingham Osteoarthritis Study

The Framingham Knee Osteoarthritis study is a population-based study of independently living elderly examining the prevalence of radiographic and symptomatic knee osteoarthritis. This group was assessed in the early 1980s at which time they had been observed for over 35 years and many risk factors for osteoarthritis had been ascertained. Results from this study suggest that knee osteoarthritis increases in prevalence throughout the elderly years, more so in women than in men. Also, studies of risk factors have shown that obesity precedes and increases the risk of knee osteoarthritis, especially in women. Other risk factors documented by the Framingham Osteoarthritis study to be important as risk factors for disease include knee injury, chondrocalcinosis, and occupational knee bending and physical labor. Radiographic knee osteoarthritis was negatively associated with smoking. No clearcut relationship of osteoarthritis with estrogen use in women was found. In terms of disability, lower extremity dysfunction is common in patients with knee osteoarthritis, but upper extremity dysfunction is not, and symptoms and severe degrees of radiographic osteoarthritis are associated with higher risks of dysfunction.