Osteoarthritis, the most common type of arthritis, occurs when the cartilage of the joints breaks down, and usually begins after a person reaches middle age. It commonly affects the knees and can be disabling.
How the study was done
To determine whether occupational or leisure-time activities could influence the risk of a person developing the condition, Dr S. Dahaghin of Tehran Medical University in Iran and colleagues compared 480 people with osteoarthritis of the knee and 490 arthritis-free controls.
People who spent more than 30 minutes daily in a squatting position were at 1.5-fold greater risk of knee osteoarthritis, while people who cycled for more than 30 minutes daily were twice as likely to have osteoarthritis in their knees, the researchers found.
People with jobs that required them to bend their knees for more than half an hour daily were about twice as likely to develop knee osteoarthritis, although the findings were of borderline statistical significance.
Housewives were also more likely than women who worked outside the home to develop knee osteoarthritis.
There was no link between playing sports or working in a non-sedentary occupation and knee osteoarthritis.
The findings support the hypothesis that overuse of a joint can influence arthritis risk, the researchers say.
"Education on preventable risk factors should be considered in order to ensure people use knee joints appropriately and avoid overuse," they conclude. – (Reuters Health, October 2009)