The biomechanical basis of vertebral body fragility in men and women

Abstract

The aim of this study was to quantify the biomechanical basis for vertebral fracture risk in elderly men and women. A bone is likely to fracture when the loads imposed are similar to or greater than its strength. To quantify this risk, we developed a fracture risk index (FRI) based on the ratio of the vertebral body compressive load and strength. Loads were determined by upper body weight, height, and the muscle moment arm, and strength was estimated from cross-sectional area (CSA) and volumetric bone mineral density (vBMD). With loads less than the strength of the bone, the FRI remains <1. For any given load, once bone strength diminishes due to a falling vBMD, the FRI will increase. Should..