Predictors of ankle and foot fractures in older women. The Study of Osteoporotic Fractures Research Group.

To determine risk factors for ankle and foot fractures, data collected from 9704 women 65 years of age or older from four areas of the United States were analyzed. Self-reported baseline questionnaires covered areas such as lifestyle factors (physical activity, diet, and smoking habits) and functional impairment (history of fracture, falling, and other diseases). Bone mineral density (BMD) and performance on neuromuscular tests were also measured. During 5.9 years of follow-up, 191 women fractured an ankle and 204 women fractured a foot. Proportional hazard models were used to estimate relative risks. In multivariable models, factors associated with ankle fracture included one or more falls in the year prior to baseline (relative risk [RR] 1.5; 95% confidence interval [CI] 1.1-2.1), greater vigorous physical activity (RR per 2 times/week, 1.2; CI 1.1-1.3), weight gain since age 25 (RR per 20% gain, 1.4; CI 1.2-1.5), self-reported osteoarthritis (RR 0.5; CI 0.3-0.8), a sister's history of hip fracture after age 50 (RR 1.7; CI 1.0-3.0), out of house < or = 1 per week (RR 3.0; CI 1.4-6.6), and low distal radius BMD (RR per -0.1 g/cm2, 1.2; CI 1.0-1.4). Factors associated with foot fracture included insulin-dependent diabetes (RR 2.9; CI 1.2-7.2), use of seizure medications (RR 2.3; CI 1.0-5.7) or of benzodiazepines (RR 1.5; CI 1.1-2.2), history of hyperthyroidism (RR 0.5; CI 0.3-1.0), poor far depth perception (RR 0.7; CI 0.5-1.0), and low distal radius BMD (RR per -0.1 g/cm2, 1.3; CI 1.1-1.5). Ankle and foot fractures have different profiles of risk factors that are largely independent of low bone mass.