Our department has the secretariat of a large Dutch cohort on patients with early complaints of hip and knee related to osteoarthritis. This very early cohort of patients with (potential) osteoarthritis of hip and knee is initiated by the Dutch Arthritis Association (Reumafonds) and is a 10 centre study including over 1000 individuals that are followed for a period of at least 10 years to monitor the natural course of early osteoarthritis.