Many neck safety technologies have been developed in recent years; however, the incidence of whiplash-associated disorders (WAD) in rear-end collision accidents remains high. A lack of consideration of individual differences among vehicle occupants is considered a major factor. Individual differences in the neck can be represented by the differences in cervical spine alignment. In this study, images of typical cervical spine alignments, such as lordotic, straight, kyphotic, s-shaped, and inverse s-shaped alignments, were selected from a hospital database. Shape transformations of a head–neck finite element model were then performed to obtain multiple head–neck finite element models with five different cervical spine alignments. Rear-end impact analysis results showed quantitative differences in relative intervertebral rotation and ligament strain. These differences might be the cause of variability in the neck injury risk and severity among occupants in rear-end impact accidents.

A finger finite element (FE) model was created from CT images of a Japanese male in order to obtain a shape-biofidelic model. Material properties and articulation characteristics of the model were taken from the literature. To predict bone fracture and realistically represent the fracture pattern under various loading conditions, the ESI-Wilkins-Kamoulakos rupture model in PAM-CRASH (ESI Group S.A., Paris, France) was utilized in this study with parameter values of the rupture model determined by compression testing and simulation of porcine fibula. A finger pinch simulation was then conducted to validate the finger FE model. The force-displacement curve and fracture load from the pinch simulation was compared to the result of finger pinch test using cadavers. Simulation results are coincident with the test result, indicating that the finger FE model can be used in an analysis of finger bone fracture during pinch accident. With this model, several pinch simulations were conducted with different pinching object’s stiffness and pinching energy. Conditions for evoking finger bone fracture under pinch loading were then estimated based on these results. This study offers a novel method to predict possible hazards of manufactured goods during the design process, thus finger injury due to pinch loading can be avoided.

Hosoyama T, et al. Clin Orthop Surg. 2024 Oct;16(5):724-732. https://doi.org/10.4055/cios23350

Distal radial fractures exhibit various fracture patterns. By assuming that the strain distribution at the distal radius affects the diversification of the fracture pattern, a parameter study using the finite element model of a wrist developed from computed tomography (CT) images was performed under different loading conditions. The finite element model of the wrist consisted of the radius, ulna, scaphoid, lunate, triquetrum, and major carpal ligaments. The material properties of the bone models were assigned on the basis of the Hounsfield Unit (HU) values of the CT images. An impact load was applied to the scaphoid, lunate, and triquetrum to simulate boundary conditions during fall accidents. This study considered nine different loading conditions that combine three different loading directions and three different load distribution ratios. According to the analysis results, the strain distribution at the distal radius changed with respect to the change in the loading condition. High strain concentration occurred in regions where distal radius fractures are commonly developed. The direction and distribution of the load acting on the radius were considered to be factors that may cause variations in the fracture pattern of distal radius fractures.