Age-related reductions in the strength of the femur tested in a fall-loading configuration

Abstract

To assess age-related changes in femoral strength as a component in the risk of fracture of the hip, we compared the loads at fracture of the proximal aspects of femora from the cadavera of older and younger individuals, as tested in a fall-loading configuration. To provide a basis for non-invasive in vivo estimates of femoral strength, we also determined the correlations between variables measured with dual-energy x-ray absorptiometry and these loads. Femora from the cadavera of eight older individuals (mean age, seventy-four years) and nine younger individuals (mean age, thirty-three years) were scanned with a Hologic QDR-2000 densitometer to obtain densitometric and geometric information. The femora were then tested mechanically in a loading configuration that simulated a fall on the greater trochanter. The femora from the older group were half as strong as those from the younger group (p < 0.001), and they absorbed one-third as much energy (p < 0.001). The area bone-mineral density of the femoral neck correlated strongly with the load at fracture (r2 = 0.92).

Clinical relevance: The prevalence of fracture of the hip increases exponentially with age. 90 percent of those fractures are the result of a simple fall from a standing height.(ABSTRACT TRUNCATED AT 250 WORDS)