Simple measurement of femoral geometry predicts hip fracture: the study of osteoporotic fractures.

Based on engineering principles, geometric measurements of femoral size should be related to femoral strength and the risk for hip fracture. To evaluate whether a simple measurement of femoral geometry is associated with hip fracture risk, we obtained dual x-ray absorptiometry scans of the proximal femur on 8074 white women age 67 or older. During an average of 1.6 years of follow-up, 64 participants suffered hip fractures. In all fracture cases and in a random sample of 134 women who did not subsequently suffer a hip fracture, we measured hip axis length (the distance from greater trochanter to inner pelvic brim), neck width, and the neck/shaft angle on the scan printout, with the observer blinded to subsequent fracture status of the participant. Results were analyzed using multiple logistic models, and odds ratios were determined. After adjustment for age, each standard deviation decrease in femoral neck bone mineral density increased hip fracture risk 2.7-fold (95% confidence interval 1.7, 4.3), and each standard deviation increase in hip axis length nearly doubled the risk of hip fracture (odds ratio = 1.8; 95% CI 1.3, 2.5). The relationship between hip axis length and fracture risk persisted even after adjustment for age, femoral neck density, height, and weight. A longer hip axis length was associated with an increased risk of both femoral neck (OR = 1.9; 95% CI 1.3, 3.0) and trochanteric fractures (1.6; 1.0, 2.4). We found no significant association between the neck width (1.1; 0.8, 1.5) or the neck/shaft angle (1.4; 0.9, 2.2) and risk of hip fracture.(ABSTRACT TRUNCATED AT 250 WORDS)