The Slovak Predictive Regression Model of Fall-Related Femoral Neck Fracture Risk

Objectives. Femur strength index (FSI) has been previously described as a reliable measure of femur fracture risk in a fall. FSI computation requires software associated with bone densitometry equipment and incorporates measures of bony structural integrity. Because such software is not universally available, in the present study, we describe the evaluation of the biomechanical predictors of femur fracture in a fall combined with commonly available measures of bony strength as an alternative means of predicting FSI values. Design. Binary logistic regression was used to evaluate the effect on the value of FSI when T-score total hip (bone densitometry results), body mass index (BMI), alpha angle, theta angle, and hip axis length (HAL) were increased by one whole unit of relevant measurement (i.e., 1 degree, 1 millimeter). Setting. Outpatient radiology facility. Participants. A sample of 3,216 East Slovak women aged 20–89 years with primary or secondary osteoporosis, osteopenia, or risk factors for osteoporosis who were referred to a facility for bone densitometry. Main outcome measures. FSI value of <1 was used as a proxy for pathological degree of fall-fracture risk. Results. A one-unit increase of the predictive variables were found to affect the odds of FSI <1 as follows: an increase by 1° of α angle = odds of FSI <1 by 1.11 times, an increase by 1° of θ angle = odds of FSI <1 by 1.23 times, an increase by 1 mm of the HAL = odds of FSI <1 by 1.04 times, an increase by 10 kg/m2 of BMI = odds of FSI <1 by 1.30 times, and an increase by +1 SD of the T-score total hip decreased the odds of FSI <1 by 1.98 times. Conclusions. The Slovak Regression Model for Fall-Related Femoral Neck Fracture Risk is an effective model for estimating fall related hip fracture based on relevant biomechanical and geometric variables. Prospective epidemiological study of fall related fracture is needed validate the model.