Objective: Whether floor activity, a common daily activity among Buddhist monks, is a risk factor for knee osteoarthritis remains controversial. The objective of the present study was to search for any association between floor activities and knee osteoarthritis.

Material and Method: This population-based survey involved 261 monks, 40 years of age or older from Songkhla province in the southern part of Thailand. Histories were taken on lifetime floor activities in four common positions, squatting, lotus, side-knee bending, and kneeling. Radiographic investigations included antero-posterior and skyline views of both knees. Diagnosis of osteoarthritis in each compartment was based on Kellgren & Lawrence grade 2 or more. Logistic regression analysis adjusted for age, body mass index and smoking status was used to identify the associations between lifetime floor activity and knee osteoarthritis.

Results: The mean age (SD) of monks in the present study was 60.4 (12.7) with mean age at ordination 44.4 (17.6) years. The lotus and side-knee bending positions were the two most common practices. Using the lowest tertile of exposure to lotus position as a reference, the third tertile had an odds ratio of 1.0 (95%CI; 0.5-2.2) associated with radiographic knee osteoarthritis. The corresponding odds ratio for side-knee bending was 0.8 (95%CI; 0.3-1.7), for squatting 2.1 (95%CI; 0.9-4.5), and for kneeling 0.7 (95%CI; 0.3-1.5).There was no significant association between the average daily lifetime floor activity in any positions and symptomatic radiographic knee osteoarthritis.

Conclusion: Floor activities involving squatting, lotus, side-knee bending and kneeling do not increase the risk of knee osteoarthritis in Thai Buddhist monks.

Keywords: Floor activity, Knee osteoarthritis