Virtual Reconstruction of Long Bone Fracture in Car-to-pedestrian Collisions Using Multi-body System and Finite Element Method

Lower limb injures are frequently observed in passenger car traffic accidents.Previous studies of the injuries focus on long bone fractures by using either cadaver component tests or simulations of the long bone kinematics,which lack in-depth study on the fractures in stress analysis.This paper aims to investigate lower limb impact biomechanics in real-world car to pedestrian accidents and to predict fractures of long bones in term of stress parameter for femur,tibia,and fibula.For the above purposes,a 3D finite element(FE) model of human body lower limb(HBM-LL) is developed based on human anatomy.The model consists of the pelvis,femur,tibia,fibula,patella,foot bones,primary tendons,knee joint capsule,meniscus,and ligaments.The FE model is validated by comparing the results from a lateral impact between simulations and tests with cadaver lower limb specimens.Two real-world accidents are selected from an in-depth accident database with detailed information about the accident scene,car impact speed,damage to the car,and pedestrian injuries.Multi-body system(MBS) models are used to reconstruct the kinematics of the pedestrians in the two accidents and the impact conditions are calculated for initial impact velocity and orientations of the car and pedestrian during the collision.The FE model is used to perform injury reconstructions and predict the fractures by using physical parameters,such as von Mises stress of long bones.The calculated failure level of the long bones is correlated with the injury outcomes observed from the two accident cases.The reconstruction result shows that the HBM-LL FE model has acceptable biofidelity and can be applied to predict the risk of long bone fractures.This study provides an efficient methodology to investigate the long bone fracture suffered from vehicle traffic collisions.

Rotary self-locking intramedullary nail for long tubular bone fractures

Background Intramedullary nails had been widely used in the treatment of long-bone fractures because of less interference of fractures and center bearing biomechanical advantage. However, it had been also found many shortcomings such as broken nails, delayed healing and was modified in order to achieve better efficacy and reduce complications. The aim of the present study is to compare the efficacy of rotary self-locking intramedullary nails （RSIN） with that of interlocking intramedullary nails （IIN） in the treatment of long-bone fractures.

Impact of the fracture on low-order guided waves in long bone

Using ultrasonic guided waves to assess long bone fractures and fracture healing has become a promising diagnostic issue. But the multimode overlap of the guided waves challenges the quantitative evaluation and clinical application. In the preformed study, in order to simplify the signal interpretation, the low-frequency sinusoidial signals were used to only excite SO and A0 modes in fractured long bones. The amplitudes of SO and A0 modes were numerically analyzed with variation in crack width and fracture angle. Numerical simulation, based on the two-dimension finite-difference time-domain （2D-FDTD） reveals that both SO and A0 amplitudes decrease with the fracture widening. However, the increase in fracture angle gradually enhances the A0 amplitude, while with respect to the SO mode, its amplitude shows a non-monotonic trend to the variation in fracture angle with a turning point around 45°. The amplitude ratio between S0 and A0 can reflect the variations in crack width and fracture angles. The simulation illustrates that ultrasonic guided SO and A0 modes are sensitive to the degree of both vertical and oblique fractures in the long cortical bone. These findings may be helpful for fractures diagnosis and healing evaluation of the long bone.