Hip fracture risks go beyond bone loss.

To guard against debilitating hip fractures, the sixth leading cause of death in persons over age 65, physicians routinely encourage older women to consume plenty of bone-strengthening calcium. A new study of French women, however, suggests that other impairments pose fracture risks equal to that of postmenopausal bone fragility.

Four centers run by INSERM, the French national medical research agency, recruited women at least 75 years old for a series of tests that measured not only the density of hip bones but also other factors that can affect vulnerability to falls-such as vision, balance, and leg strength. Over the next 2 years, 154 of the 7,575 volunteers in the study suffered first-time hip fractures. For that group, a set of four vulnerability factors proved as reliable at predicting hip fractures as bone density, currently the gold standard of fracture risk. The factors-poor vision, slow gait, difficulty performing a tandem walk (where the heel of one foot is placed immediately in front of the toe of the other), and small calf circumference (a gauge of leg muscle)-were reported in the July 20 Lancet.

In a given year, 1.1 percent of women who had either thin hip bones or this quartet of vulnerability factors could be expected to develop a fall-related fracture, points out lead author Patricia Dargent-Molina of INSERM in Villejuif. Her study found that 2.8 percent of those with both types of risk factors could be expected to fracture a hip-more than five times the incidence in women with neither thin bones nor a high fall-vulnerability profile. The likelihood of falling is much greater "if you have reduced neuromuscular capacity," observes Jan Lexell of Lund (Sweden) University Hospital. Now, he says, science must identify the source of such impairments-whether it is loss of muscle, of the nerves that trigger muscular action, or both. Dargent-Molina notes that her new findings "suggest ways to prevent fractures that don't rely on drugs that act on bone."

Mary E. Tinetti of Yale University has investigated strategies to cut the risk of falls in the elderly. By looking at a combination of factors, she says, the new French study provides a focus for designing cost-effective exercise and behavioral modification programs.

Tinetti cautions, however, that since the French don't fortify foods with vitamin D, which is important to bone and muscle health, women in INSERM's study may face higher fracture risks than most U.S. women.