Geometrically accurate 3D FE models from medical scans created to analyse the causes of sports injuries

Development of Finite Element (FE) modelling techniques has allowed the creation of 3D models based upon high resolution Computed Tomography (CT) images, which have been used to assess the mechanical properties of bone, fixation techniques, and the performance of bone micro-architecture. In this study, a semi-automated process for converting CT data into FE models has been used to investigate if the automated geometry and material properties mapping of mid-shaft cortical bone. In order to develop the process, a porcine femoral specimen was imaged with a spiral CT scanner, allowing the semi-automated creation of a 3D FE model. Inhomogeneous material properties were mapped using the Bonemat algorithm which allows automated adjustment of values from CT data. The 3D model was cropped at the start of each metaphyseal region to isolate the mid-shaft region for testing. Hand calculation of the mid-shaft was undertaken using a composite ellipse solution, which allowed the direction and magnitude of the maximum stresses, and the deflection occurring within the bone mid-shaft to be analysed with respect to the results obtained within the finite element testing. Predictions from the ellipse method correlated significantly well with the stress patterns and maximum deflections achieved within the 3D FE model, validating the modelling process for future testing. Using CT-derived FE analysis to determine failure mechanisms has great potential for use as a tool in fracture analysis. The increased geometrical accuracy has potential for use within Sports Injuries studies, where the inherent complexity of skeletal modelling and multi-factor loading conditions can often lead to errors in simplified solutions. Further understanding of failure mechanisms such as these can be used to influence the design of sports equipment and surfaces, helping to prevent sports injuries in the future.