Incidence of Chronic and Other Knee Pain in Relation to Occupational Risk Factors in a Large Working Population.

OBJECTIVES The aim of this study was to estimate the incidence of chronic and other knee pain (KP) in relation to occupational and personal risk factors among workers representative of a general working population. METHODS Of 3710 workers in a French region included in a surveillance network for musculoskeletal disorders (2002-2005), 2332 completed a follow-up questionnaire in 2007-2009 (Cosali cohort). The questionnaires included questions on musculoskeletal symptoms, and personal and occupational exposure. Incident cases of KP in 2007-2009 (i.e. with KP at follow-up but not at baseline) were dichotomized into chronic KP (>30 days in the previous year) and other KP. Associations between incident KP and personal and occupational factors at baseline were studied separately according to sex using multinomial logistic regression. RESULTS Of the 1616 respondents without KP at baseline, 122 (7.5%) reported chronic KP and 243 (15.0%) reported other KP. The incidence rate of chronic KP was estimated at 19.6 per 1000 worker-years (95% CI: 16.3-23.5). After adjustment for age and body mass index, significant associations were found between incident chronic KP and handling loads >4kg [odds ratio (OR) 2.1 (1.2-3.6) for men, OR 2.3 (1.1-5.0) for women] and kneeling >2h a day for men [OR 1.8 (1.0-3.0)]. CONCLUSIONS This study highlights the high frequency of chronic KP in the working population and the role of occupational factors in its incidence, in particular those kneeling and handling loads.