Reconstruction of Fall Injuries for Children of Different Ages

Sammanfattning: The idea to use finite element (FE) models to reconstruct accidents for humans is becoming more popular the last years. They represent the human body very accurately and indicate well changes in shape, size and biomechanical properties. FE models are useful when looking at complex factors in the human body in a more systematic way and when the approach is too complicated for conventional setups. Positioned child models from PIPER were used in the process and then rotated in LS-PrePost according to impact points and impact velocities from a given literature data where information from witnessed fall accidents of children was given. The simulations were finally run in LS-Dyna and the purpose was to investigate if the resulting brain injuries were similar to the real life data. From the literature, the falling distance from lowest point of the body to the ground, the age of the child, gender, type of ground and results from CT scans were all known. To compare the results to the literature data, section cuts of the brain were taken at four locations with different time steps. Biomechanical injury predictors such as brain strain, acceleration, rotational angular acceleration and rotational angular velocity were observed and helped with the comparison. In total, 12 cases were reconstructed which ended as 22 simulations. Due to uncertainty regarding the falling height when the children fell from a swing, each swing case had 3 scenarios. Overall the comparison of predicted injury locations from LS-Dyna to real injury locations from CT scans indicated that 7 out of 12 cases compared relatively well. The comparison of a 23-month-old girl to the same case reconsructed with CRABI-18 showed similar outcomes of the angular acceleration and the angular velocity. The linear acceleration and HIC were however much higher with LS-Dyna. Comparison between the swing cases of a 10-, 12- and 13-year-old resulted in similar results for the 12- and 13 year-old girls but the 10 year boy had lower values for all biomechanical parameters except the angular velocity which was a bit higher. With more detailed information about real accidents and precise scaling of PIPER child models, reconstruction with LS-Dyna could be useful in the future to design safer playgrounds for children and to obtain injury criterion for children after fall incidents.