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Outward Knee Alignment Increases Arthritis Risk, Finds NIH-funded Study

Aug 19, 2010; 1:51 PM ET

People with a particular kind of knee alignment have a greater chance of developing osteoarthritis than do those with other types of leg alignment, reported researchers supported by the National Institutes of Health.

The study authors found that the higher risk occurred among those with an outward-facing alignment-knees relatively far apart and ankles closer together. Known as varus alignment, the knee configuration resembles bowleggedness, but is not as extreme.

Osteoarthritis (http://www.niams.nih.gov/Health_Info/Osteoarthritis/default.asp) results from the deterioration of cartilage, the hard, slippery material that cushions the ends of bone at the joints. The condition causes pain and often results in disability. According to the Centers for Disease Control and Prevention, osteoarthritis of the knees (http://www.cdc.gov/arthritis/basics/osteoarthritis.htm) affects 6.1 percent of all adults over age 30.

The current finding, from a two and one half year study of nearly 3,000 people, may lead to the development of new ways to prevent osteoarthritis of the knee or lessen its symptoms.

The researchers also confirmed earlier findings that for people who have arthritis, varus alignment as well its opposite, the valgus, or inner facing, alignment contribute to worsening of the condition on the side of the knee bearing more stress.

"The study authors have shown that the varus alignment is a risk factor for osteoarthritis of the knees," said Nancy Shinowara, Ph.D., a health scientist administrator in the National Center for Rehabilitation Research of the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). "Future research may lead to new ways to reduce the stress that the condition places on knees and, in so doing, prevent osteoarthritis or lessen its severity."

The study was published online in Annals of the Rheumatic Diseases. NIH's National Institute of Aging also provided funding for the study.

First author Leena Sharma, M.D., of Northwestern University's Feinberg School of Medicine in Chicago, conducted the study, with researchers there and at Boston University, the University of Alabama at Birmingham; the University of Iowa, Iowa City; Queens University in Kingston, Ontario; OAISYS, Inc., Kingston, Ontario; and the University of California, San Francisco.

The researchers followed 2,713 volunteers from Birmingham and Iowa City. The participants, from 50 to 79 years of age, had arthritis or were at increased risk of developing the condition because they were overweight, had a previous knee injury or previously had knee surgery.

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