Determination of biomechanical parameters from dual X-ray absorptiometry measurements

Abstract

Osteoporotic hip fractures represent a high risk for people over 60 years of age, with a reduction in life expectancy of 20% and a reduction in functional capacity of 50%. Currently, dual X-ray absorptiometry (DXA) is the gold standard for the diagnosis of osteoporosis, although it has a low prediction capacity of bone fracture. Likewise, there exist other techniques such as quantitative computed tomography measurements with a better prediction of bone fracture, although limited in practice due to their high radiation doses. On the other hand, finite element models (FEM) represent a tool that provides complementary information, such as strength and stress, which can be better predictors of hip fractures. Thus, the combination of advanced DXA images with FEM allowed a better discrimination of fracture and non-fracture cases with high accuracy. However, the application of these models in clinical practice is complicated due to the computational time and data processing. Therefore, it would be of interest to find an alternative way to calculate such parameters in a shorter time without the need to perform such FEM simulations. With this in mind, the aim of this project is to explore statistical methods to correlate DXA measurements and mechanical stress and strain parameters obtained by FEM simulations. To carry out the study, it initially started from a database of 111 patients including DXA measurements and mechanical parameters derived from previous FEM simulations, which were subsequently expanded to balance the number of patients between males and females. Afterwards, correlation analysis was performed to extract the minimum significant DXA parameters for the prediction of mechanical parameters. It was done using a SSPS statistical program. Likewise, a comparison between men and women was also performed, as well as other types of regressions and a comparison considering the type of hip fracture (distinguishing between neck and trochanter). The study showed that the regression between the DXA measurements and the biomechanical parameters of stress and strain were different between osteoporotic patients without fracture and fractured patients because the structural changes that occur in the bone are not only due to the amount of bone mineral density but also because they have different mechanical behavior from one case to another.