To investigate the assosiation between squatting and the prevalence of knee osteoarthritis (OA) among elders in Beijing.
We recruited a random sample of Beijing residents age > or =60 years. Subjects answered questions on joint symptoms, and knee radiographs were obtained. Subjects were also asked to recall the average amount of time spent on squatting each day at youth (25 years or so).
Among the studied subjects, 40% of the men and 68% of the women reported squatting > or = 1 hour per day at youth. The prevalence of tibiofemoral OA increased in both men and women. Compared with subjects who squatted <30 minutes per day at youth, the multivariable-adjusted prevalence odds ratios of tibiofemoral OA were: 1.1 30-59 minutes/day for those spent on squatting, 1.0 for 60-119 minutes/day, 1.7 for 120-179 minutes/day, and 2.0 for 180 minutes/day among the men (P for trend= 0.074), while the respective odda ratios among women were 1.4, 1.3, 1.2 and 2.4 (P for trend = 0.077) but a weaker association with patellofemoral OA was found.
Prolonged squatting was a strong risk factor for tibiofemoral knee OA among elderly in Beijing.