Osteoarthritis of the knee is a common problem in older persons. Established risk factors for this disorder include older age, female sex, osteoarthritis in other joints, obesity and prior knee injury or surgery. Some studies suggest that knee osteoarthritis may be more common in persons who perform heavy physical activity, particularly kneeling and squatting. Coggon and colleagues assessed the risk of knee osteoarthritis in association with occupational activities.

Patients who were scheduled for surgical treatment of knee osteoarthritis were enrolled in the study. A similar group of persons from the community who were matched for age and sex were enrolled in the study as the control group. The data collection for both groups included history of knee injury, occupational activities, height and weight, and the presence or absence of Heberden's node of the hands.

When controlling for body mass index, history of knee injury and evidence of hand osteoarthritis, patients who reported long kneeling and squatting, walking more than 2 miles per day and lifting at least 25 kg regularly were at significantly higher risk for knee osteoarthritis. In addition, people who had a body mass index of 30 or more kg per m² and whose work required prolonged kneeling and squatting had a significantly higher risk of knee osteoarthritis.

The authors conclude that strong evidence shows occupational activities that include prolonged squatting and kneeling significantly increase the risk for developing knee osteoarthritis. Obesity adds to this risk. There is a need to identify this condition as an occupational hazard and to develop strategies to reduce the risk.