The aim of the Frederiksberg Cohort is to identify self-reported predictors of knee pain and knee OA in elderly. The Frederiksberg Cohort is a survey-based inception cohort initiated in 2018 with a questionnaire sent to all citizens between 60-69 years in Frederiksberg Municipality. Citizens who agree to it will receive a questionnaire once a year until 2028. The questionnaire is focused on lifestyle measures and use of recommended as well as complementary and alternative medicine for health and for knee pain. It furthermore contains questions concerning knee pain related functional level, quality of life and illness perceptions.