Research
The role of cumulative physical work load in symptomatic knee osteoarthritis – a case-control study in Germany
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* Corresponding author: Andreas Seidler seidler.andreas@baua.bund.de
1 Federal Institute of Occupational Safety and Health, Berlin, Germany
2 Division of Occupational Health, RP Darmstadt, Wiesbaden, Germany
3 Institute of Diagnostic and Interventional Radiology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
4 OncoRay – MI OncoRay, Dresden, Germany
5 Institute of Occupational Medicine, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
6 The members of the knee osteoarthritis study-group are defined under Acknowledgements
Journal of Occupational Medicine and Toxicology 2008, 3:14 doi:10.1186/1745-6673-3-14
Published: 14 July 2008Abstract
Objectives
To examine the dose-response relationship between cumulative exposure to kneeling and squatting as well as to lifting and carrying of loads and symptomatic knee osteoarthritis (OA) in a population-based case-control study.
Methods
In five orthopedic clinics and five practices we recruited 295 male patients aged 25 to 70 with radiographically confirmed knee osteoarthritis associated with chronic complaints. A total of 327 male control subjects were recruited. Data were gathered in a structured personal interview. To calculate cumulative exposure, the self-reported duration of kneeling and squatting as well as the duration of lifting and carrying of loads were summed up over the entire working life.
Results
The results of our study support a dose-response relationship between kneeling/squatting and symptomatic knee osteoarthritis. For a cumulative exposure to kneeling and squatting > 10.800 hours, the risk of having radiographically confirmed knee osteoarthritis as measured by the odds ratio (adjusted for age, region, weight, jogging/athletics, and lifting or carrying of loads) is 2.4 (95% CI 1.1–5.0) compared to unexposed subjects. Lifting and carrying of loads is significantly associated with knee osteoarthritis independent of kneeling or similar activities.
Conclusion
As the knee osteoarthritis risk is strongly elevated in occupations that involve both kneeling/squatting and heavy lifting/carrying, preventive efforts should particularly focus on these "high-risk occupations".