Fall Characteristics, Functional Mobility and Bone Mineral Density As Risk Factors of Hip Fracture in the Community-dwelling Ambulatory Elderly

Hip fracture is the most serious consequence of osteoporosis, frequently occurring in the elderly; however, no research has been performed to identify the fall characteristics, functional mobility and bone mineral density (BMD) concurrently as risk factors. We investigated the risk factors of hip fractures using a multifactorial approach for a further preventive strategy. This age- and sex-matched case-control study was conducted in a community-based general hospital. A total of 252 consecutive community-dwelling ambulatory elderly, aged between 65 and 85 years, were studied: 127 patients (faller with hip fracture) and 125 controls (faller without hip fracture). Body mass index (BMI), predisposing medical conditions, fall characteristics, functional mobility and BMD of the hip were evaluated by direct interview and clinical examination. In the final model of multivariate regression analysis, risk factors for hip fracture were direct hip impact (adjusted odds ratio (OR), 4.9; 95% confidence interval (CI), 2.7-8.8), previous stroke (adjusted OR, 2.9; 95% CI, 1.3-6.3), sideways fall (adjusted OR, 2.5; 95% CI, 1.6-3.9), functional mobility (a decrease of 1 SD; adjusted OR, 2.0; 95% CI, 1.1-3.5), BMI (a decrease of 1 SD; adjusted OR, 1.8; 95% CI, 1.1-2.8) and femoral neck BMD (a decrease of 1 SD; adjusted OR, 1.7; 95% CI, 1.0-2.8). The effect of risk factors remained the same in different analysis sets, and adding or removing femoral neck BMD did not change other risk factors, though BMD was significantly correlated with functional mobility and BMI. Importantly, both sideways fall and direct hip impact are independent predictors of hip fracture. From these results, we suggest a preventive strategy of hip fracture in the elderly: besides the maintenance of BMD, keeping an appropriate body weight and maintaining a physically active lifestyle might be crucial.