NIH-Funded Study Finds Outward Knee Alignment Increases Arthritis Risk

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 NIH and its National Institute of Aging.

The study, published online in Annals of the Rheumatic Diseases, 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, according to a press release.

According to the CDC, osteoarthritis of the knees affects 6.1% of all adults older than age 30 years.

The study findings, from a more than 2 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 as its opposite, the valgus, 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,” Nancy Shinowara, PhD, 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), stated in the release. “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.”

First author Leena Sharma, MD, 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 years 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.

The research team found the varus stance was associated with 1.49 times the risk of developing arthritis compared with a straight-legged stance, whereas there was no increased risk for the valgus stance. The researchers statistically compensated for potentially complicating factors such as knee stability, muscle strength, and body weight.

“Our results suggest the need to design interventions for people with varus alignment, in hopes of redistributing stress and possibly helping to prevent knee arthritis before it develops,” Sharma stated.

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