Leg-Stand Test Predicts Hip-Fracture Risk in Women

Nancy A. Melville

September 13, 2014

HOUSTON — The inability to stand on 1 leg for 10 seconds or to squat down to reach the floor represent strong early predictors of hip fracture and mortality in postmenopausal women, according to a 15-year follow-up study presented here at the American Society for Bone and Mineral Research (ASBMR) 2014 annual meeting.

"Squatting down to reach a floor and maintaining balance on 1 foot for a moment are essential functional abilities and very simple to measure," first author Toni Rikkonen, PhD, of the University of Eastern Finland, in Kuopio, told Medscape Medical News.

"Inability to accomplish either of them demonstrates functional decline with increased risk of mortality and fractures."

While bone-mineral-density tests and other measures provide essential information on when a patient may need stepped-up osteoporosis prevention, research on signs of physical deterioration that can predict hip fracture is lacking.

In an effort to better identify such signs, Dr. Rikkonen and colleagues evaluated data on 2791 women in the Osteoporosis Risk Factor and Prevention Study (OSPRE). The women in the trial had a mean age of 59.1 years, and their measurements on functional capacity and femoral neck bone-mineral density (FN BMD) were available.

At a mean follow-up of 13.1 years, 578 fractures were reported among the women, including 35 hip fractures, and there were 258 deaths (9.2%).

At baseline, the women were asked to perform 3 physical tests that were considered to indicate physical capacity — the ability to squat down and touch the floor; the ability to stand on one leg for 10 seconds; and grip strength (with weakest grip indicative of inability to perform the test).

A total of 1587 women (56.9%) showed no functional decline at baseline according to these physical tests and were considered to be the reference group.

Compared with the reference group, the women who did have signs in any of the 3 categories of functional decline (n = 1204) had a significantly higher risk for hip fracture (hazard ratio [HR], 4.6; P = .001).

Risk for mortality was also higher (HR, 1.5; P = .001), as was the risk for any fracture (HR, 1.5; P = .001) among those showing inability to perform any of the 3 tests.

Women who were unable to complete the leg-stand test, however, had the highest risk for hip fracture, with a hazard ratio of 8.4 (P = .001), compared with those who could complete the test.

The second strongest predictor of hip fracture was failure in squatting and touching the floor, with an HR of 5.2 (P = .001), followed by a weak grip strength (HR for hip fracture, 4.3; P = .001).

The results remained consistent after adjustment for factors including FN BMD, age, body mass index (BMI), and smoking.

Only modest increases in risk were seen when the risk factors were combined, and adjustments for factors including FN BMD and age or adjusting mortality risk for BMI and smoking did not change the results.

Dr. Rikkonen said the findings were particularly notable considering the women's ages.

Results Surprising, Given Young Age of Women

"Since women in the OSTPRE study were followed from 59 to 74 years, it is still a bit of a young cohort to study hip fractures, so indeed the result was a bit surprising," he said.

The findings underscore the importance of balance in the value of a 1-leg stand challenge as an indicator, Dr. Rikkonen noted.

"The inability to stand on 1 foot is mostly dependent on balance and coordination. In addition, unilateral posture demands your hip and core muscles to compensate accordingly with the task and to provide additional support for the body," he explained.

"Standing on 1 foot challenges both of these properties, muscle coordination and balance, which might explain having the most predictive value among tests."

The failure to complete a challenge is, however, something that can in many cases be improved on.

"Functional limitations are usually modifiable," Dr. Rikkonen said. "These patients should be encouraged to use their legs and train their balance in a safe manner, regardless of their age."

Michael R. McClung, MD, director of the Oregon Osteoporosis Center and moderator of the session, agreed that the findings provide further support of evidence on the key risks associated with falls and fracture.

"These data go with the well-known association of falls and risk of falls and hip-fracture risk," he told Medscape Medical News.

"The standing-on-1-leg test correlates with strength and balance, both of which are strong predictors of falls," he added.

However, while there is plenty of evidence showing the efficacy of medications in reducing fractures, less is known on the benefits of other strategies, Dr. McClung noted.

"Whether managing patients with strategies to improve strength and balance reduces fracture risk is unknown. Thus, while interesting, I do not see these data changing clinical practice."

Dr. Rikkonen and Dr. McClung reported no relevant financial relationships.

American Society for Bone and Mineral Research 2014 Annual Meeting; September 13, 2014; Houston, Texas. Abstract FR0455.

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