title: Associations between floor activities and knee osteoarthritis in Thai Buddhist monks: the Songkhla study.
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  Floor activities involving squatting, lotus, side-knee bending and kneeling do not increase the risk of knee osteoarthritis in Thai Buddhist monks.
authors.affiliation: Department of Orthopaedic Surgery and Physical Medicine, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand. boonsin.b@psu.ac.th
authors.forename: Boonsin
authors.initials: B
authors.lastname: Tangtrakulwanich
authors.forename: Virasakdi
authors.initials: V
authors.lastname: Chongsuvivatwong
authors.forename: Alan F
authors.initials: AF
authors.lastname: Geater
mesh_terms: D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D005430:Floors and Floorcoverings; D006801:Humans; D007717:Knee / Q000000981:diagnostic imaging / Q000502:physiology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D015995:Prevalence; D011859:Radiography; D012307:Risk Factors; D012907:Smoking; D013785:Thailand