January 8, 2008

Kneeling, Standing on the Job Boosts Arthritis Risk

Research shows that modifications to work methods may be necessary to reduce the risk of knee osteoarthritis. Occupations that force workers to spend significant amounts of time kneeling or standing cause a significant increase in knee osteoarthritis, according to a study led by Dr. Alfred Franzblau of the University of Michigan School of Public Health in Ann Arbor. There have been many studies that have suggested this connection, however few have quantified the amount of time spent kneeling or standing that actually increases the risk of knee osteoarthritis.

In Franzblau's study, 1,970 people were evaluated who had been on their longest-held job for a minimum of 5 years. Franzblau's team had five ergonomics experts rate occupations based on how much time a worker would spend each day sitting, standing, walking or running, carrying or lifting loads greater than 22 pounds, kneeling, or working in a cramped space. Using the X-rays from these 1,970 people along with the information from the ergonomics experts, Franzblau's team found that occupations requiring the most kneeling and heavy lifting tripled knee osteoarthritis. Jobs requiring a large amount of time standing during the workday also greatly increased the risk.

Franzblau and his team found that 21 percent of knee osteoarthritis cases in men are due to working in jobs that require kneeling for more than 14 percent of the workday, such as nursery or farm work, or construction jobs such as floor-laying. Of the group studied, very few women (5 percent) had jobs that required kneeling, but a very high percentage had jobs that required them to stand for a third of their work day. Many of these women were machine operators or worked in sales professions. Based on these findings about 19 percent of cases of knee osteoarthritis in women are due to their occupation. In order to reduce these percentages, changes must be made to particular work methods.