Squatting, sitting on the floor, or cycling: are life-long daily activities risk factors for clinical knee osteoarthritis? Stage III results of a community-based study.
OBJECTIVE
To evaluate the association between occupations, sports, life-long daily activities, and knee osteoarthritis.


METHODS
In this case-control study, we randomly recruited 480 subjects with knee osteoarthritis, who had participated in the first stage of a community-based study in Tehran, and compared them with 490 controls. A questionnaire was used to record all occupations, sports, and the details of 10 daily activities. The mean +/- SD hours/day spent on these activities were calculated and compared using the lightest activity as reference. Generalized estimation equation was used with each knee as the unit of analysis.


RESULTS
The mean +/- SD age and percentage of female distribution was 57 +/- 12 years, 69.8% women for cases, and 46.8 +/- 15 years, 64.1% women for controls. After adjusting for age, sex, and body mass index, 2 activities were risk factors for knee osteoarthritis: prolonged squatting (odds ratio [OR] 1.51, 95% confidence interval [95% CI] 1.12-2.04) and cycling (OR 2.06, 95% CI 1.23-3.45). Knee-bending had borderline significance (OR 1.98, 95% CI 0.98-3.99). Carrying loads (OR 1.24, 95% CI 0.87-1.76) or climbing stairs (OR 0.99, 95% CI 0.69-1.42) showed no extra risk for knee osteoarthritis. Prolonged standing, sitting on the floor, and walking up/downhill were not risks for knee osteoarthritis. Housewives were at greater risk (borderline-significant) of developing knee osteoarthritis (OR 1.68, 95% CI 0.93-3.03) than women whose main occupation was outside the home. Other types of jobs and sports did not show an extra risk of knee osteoarthritis.


CONCLUSIONS
Our findings support the role of lifestyle in the pathogenesis of knee osteoarthritis for squatting and cycling. Education on preventable risk factors should be considered in order to ensure people use knee joints appropriately and avoid overuse.
Dahaghin
S
S
+-Shariati Hospital, Tehran University, Tehran, Iran. s_dahaghin@yahoo.com
Tehrani-Banihashemi
S A
SA
Faezi
S T
ST
Jamshidi
A R
AR
Davatchi
F
F
D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001642:Bicycling; D016022:Case-Control Studies; D005260:Female; D005430:Floors and Floorcoverings; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000209:etiology; D016017:Odds Ratio; D020370:Osteoarthritis, Knee / Q000209:etiology* / Q000503:physiopathology; D011187:Posture; D016059:Range of Motion, Articular; D012307:Risk Factors; D013177:Sports; D055815:Young Adult