How Arthritis Gets a Toehold

Walking in high heels does more than just spur bunions and lower back pain--it also may lead to bum knees, researchers report in tomorrow's Lancet.

Joints are normally cushioned by cartilage. If this protective tissue wears down, bones scrape against one another and can trigger painful inflammation. This osteoarthritis, according to the Centers for Disease Control and Prevention, is the most prevalent cause of chronic disability among people over 65 and afflicts 40 million people in the United States. A major reason the cartilage degrades is "undue wear and tear on a joint," says Casey Kerrigan, a physician at Spaulding Rehabilitation Hospital and Harvard Medical School in Boston.

To find out why twice as many women as men suffer from osteoarthritis, Kerrigan's team recruited 20 women in their mid-30s who felt comfortable in high-heeled shoes. The researchers used sensors to measure force on the volunteers' hips, ankles, and knees as they walked in high heels or barefoot, and they analyzed a videotape of the women walking. The scientists discovered that walking in high heels applied on average 23% more force on knee joints than walking barefoot. The reason is that high-heeled shoes shift the body forward and restrict ankle motion, forcing the knees to absorb more stress to maintain balance.

"If [high heels] increase mechanical stress on knees, then that would potentially be a risk factor for osteoarthritis," says Mark Chance, a biophysicist at Albert Einstein College of Medicine in the Bronx. To the millions of women who wear high-heeled shoes, Kerrigan urges: "Ignore the fashion and pick flat shoes."

Posted in Biology, Physics