Risk of fracture in elderly patients: a new predictive index based on bone mineral density and finite element analysis.

Hip fracture is more and more frequent in elderly population. For this reason, an increasing attention has been focused on the development of a non-invasive method to predict femoral neck fracture. A conventional approach to fracture diagnosis is the measurement of bone mass by dual-energy X-ray absorptiometry in some regions of interest. The aim of this work is to assess a method that accounts for the structural details of the bone providing a more direct determination of strength properties, and improving the diagnostic power of the current densitometric systems. A 2D finite element model of the proximal femur is derived from dual-energy X-ray absorptiometry data. Initially, the method is validated in vitro using a replica of the human femur. The predicted results are compared to strain-gauge measurements and to a 3D finite element model, with good agreement being observed. Then, an in vivo preliminary study on a limited group of patients is carried out. The loading condition that simulates a fall to the side onto the greater trochanter from standing height is employed. All simulations show a peak strain at the femoral neck region with a strain distribution typical of a fall on the side. The proposed method seems to supply a useful tool for the in vivo analysis of the risk of hip fracture.