Fig. 1From: Leisure time physical activity and the risk of hip or knee replacement due to primary osteoarthritis: a population based cohort study (The HUNT Study)Flow chart of the study population. HUNT = The Nord-Trøndelag Health Study, HUNT2 (1995-97) and HUNT3 (2006-08), THR = total hip replacement, TKR = total knee replacement, LPA = leisure time physical activityBack to article page