Influence of physical activity-related joint stress on the risk of self-reported hip/knee osteoarthritis: a new method to quantify physical activity

Background The relationship between physical activity (PA) and the development of hip/knee osteoarthritis (OA) has not been clearly defined. The purpose of this study was to develop a method to quantify PA-related joint stress and to assess its influence on the risk of hip/knee OA. Methods Participants in a large longitudinal study, without knee/hip OA (n = 5284), were asked about their PA participation in 1986. PA-related joint stress was calculated using information on the frequency, intensity, and duration of individual types of PA, and incorporated a quantification of joint stress. Self-reported, physician-diagnosed hip/knee OA was ascertained by survey in 1990, 1995, and 1999 (average length of follow-up: 12.8 years). Results The joint stress PA score was not associated with an increased risk of hip/knee OA. Also, among walkers and runners there was no association between the frequency, pace, or weekly training mileage and hip/knee OA. Older age, previous joint injury and surgery, and higher body mass index were confirmed as independent risk factors for hip/knee OA. Conclusions Participation in PA as an adult does not increase the risk of hip/knee OA and there does not seem to be a threshold of increasing risk with increased training among walkers and runners.