Study of hip fracture risk by DXA-based patient-specific finite element model.

A number of factors may have effects on hip fracture, for example, bone mineral density (BMD), body weight and height, femur length, femoral neck length, etc. It is not clear which factor(s) has the dominant effect on hip fracture. Therefore, the factors were investigated by a previously developed DXA (dual energy X-ray absorptiometry) based finite element model. The finite element model is patient-specific, as all information required in constructing the model was extracted from the patient's hip DXA image. DXA images of 180 patients were obtained from the Manitoba Bone Mineral Density Database. For each patient, a finite element model was constructed and fracture risk indices (FRI) were calculated at the three critical locations on the hip, i.e. the femoral neck, the intertrochanter and the subtrochanter. Possible correlations between the fracture risk indices and the factors were then investigated. The obtained results indicated that, for hip fractures resulted from lateral fall, areal BMD and patient's body weight are two dominant factors, but effects from the other factors are not trivial. The study suggested that hip fracture is the result of combined effects from all the factors. Therefore, use of areal BMD alone in clinical assessment of fracture risk is not reliable.