Development and validation of a distal radius finite element model to simulate impact loading indicative of a forward fall

Abstract

The purpose of this work was to develop and validate a finite element model of the distal radius to simulate impact loading. Eight-node hexahedral meshes of the bone and impactor components were created. Three separate impact events were simulated by altering the impact velocity assigned to the model projectile (pre-fracture, crack and fracture). Impact forces and maximum and minimum principal strains were calculated and used in the validation process by comparing with previously collected experimental data. Three measures of mesh quality (Jacobians, aspect ratios and orthogonality) and four validation methods (validation metric, error assessment, fracture comparisons and ensemble averages) assessed the model. The element Jacobians, aspect ratios and orthogonality measures ranged from 0.08 to 12, 1.1 to 26 and -70° to 80°, respectively. The force and strain validation metric ranged from 0.10 to 0.54 and 0.35 to 0.67, respectively. The estimated peak axial force was found to be a maximum of 28.5% greater than the experimental (crack) force, and all forces fell within ±2 standard deviation of the mean experimental fracture forces. The predicted strains were found to differ by a mean of 33% across all impact events, and the model was found to accurately predict the location and severity of bone damage. Overall, the model presented here is a valid representation of the distal radius subjected to impact.

An ex vivo experiment to reproduce a forward fall leading to fractured and non-fractured radii

“…Regarding strain analysis, the highest strain was found at the ulnar side, as observed in a previous 156 study (Burkhart et al, 2014). Apart from qualitative observations of the strain pattern during the 157 loading, the strain field will be used in future studies to compare experimental fracture patterns 158 revealed by strain distributions and strains computed from numerical models.…”

Prediction of the mechanical response of canine humerus to three-point bending using subject-specific finite element modelling

“…Including progressive damage in the model may lead to better results as the physical phenomenon leading to bone non-linear behaviour is most probably related to damage rather than plasticity. 21,34,38,44 No distinction was made between cortical and trabecular tissues in the bone material properties characterizing the non-linear behaviour, although the microstructures of these tissues are clearly different. It is likely that here the trabecular tissue do not participate substantially to the bone bending response.…”

Simplified boundary conditions alter cortical-trabecular load sharing at the distal radius; A multiscale finite element analysis

“…Cortical-trabecular load sharing along the length of the micro-FE section was compared between the physiologic (multiscale) and platen-compression BCs. Correlations between curves were assessed using the cross-correlation (CC) function in Matlab, and the method of Oberkampf and Trucano [OT (Burkhart et al, 2014; Oberkampf and Trucano, 2002)] as follows, V=1−1Ntrue∑tanh0.2em[italicabs(Loaditalicplaten−LoaditalicphysiologicLoaditalicphysiologic)]where N is the number of data points, and V = 1 indicates perfect correlation. For an overall perspective, percent cortical-trabecular load share averaged across the micro-FE section was also compared between BCs using paired statistical comparisons.…”