Finite element prediction of surface strain and fracture strength at the distal radius

To better understand the mechanisms underlying distal radius fracture we have developed finite element models to predict radius bone strain and fracture strength under loading conditions simulating a fall. This study compares experimental surface strains and fracture loads of the distal radius with specimen-specific finite element models to validate our model-generating algorithm. Five cadaveric forearms were instrumented with strain gage rosettes, loaded non-destructively to 300 N, and subsequently loaded until failure. Finite element models were created from computed tomography data; three separate density-elasticity relationships were examined. Fracture strength was predicted for three specimens that failed at the distal radius using six different failure theories. The density-elasticity relationship providing the strongest agreement between measured and predicted strains had a correlation of r=0.90 and a root mean squared error 13% of the highest measured strain. Mean absolute percent error (11.6%) between measured and predicted fracture loads was minimized with Coulomb-Mohr failure theory and a tensile-compressive strength ratio of 0.5. These results suggest that our modeling method is a suitable candidate for the in vivo assessment of distal radius bone strain and fracture strength under fall type loading configurations.