There were significant differences in the risk of KOA with age (OR 1.718; 95% CI 1.289 - 2.291), female (OR 3.556; 95% CI 1.599 - 7.907), body mass index (OR 1.165; 95% CI 1.067 - 6.773), kneeling (OR 2.688; 95% CI 1.067 - 6.773), and squatting (OR 2.042; 95% CI 1.041 - 4.005).