Impact of intertrochanteric cortical thickness on hip fracture types under dynamic load: A finite element analysis / 医学研究生学报

ABSTRACT

Objective The influence of intertrochanteric cortical thickness on hip fracture can be investigated by the finite element method (FEM), but few dynamic FEMs have been established to manifest the extension of the crack. This study aimed to investigate the influence of intertrochanteric cortical thickness on the proximal femoral fracture types by FEM.Methods We recruited a healthy male volunteer from the Department of Traumatic Orthopedics, the First Affiliated Hospital of Guangzhou University of Chinese Medicine in October 2017, established a 3-dimention model, and reconstructed thick, middle and thin intertrochanteric cortex proximal femur models by meshing, defining material properties and setting boundary conditions. We measured the crack moment and von Mises stress, distribution of the fracture line, and the time-stress curves of the earliest damage element.Results Fracture occurred the earliest in the thin-cortex femur model but the latest in the thick one. The von Mises stress contour plot showed that, when damage started, the stress was concentrated on the posterior femoral neck and intertrochanteric region, extending to the posterior inferior part of the lesser trochanter in all the three models and, with the decline of the intertrochanteric cortex thickness, the concentration of the von Mises stress gradually narrowed down and shifted to the intertrochanteric region. The narrowing of the von Mises stress was the most obvious in the thin-cortex model, mainly distributed on the junction of the basal femoral neck and the intertrochanteric region. With the thinning of the cortex, the lesser trochanter became the region of stress concentration. The time-stress curves showed that fracture occurred the earliest in the thin-cortex model, with the maximum stress of 51.6 Mpa, but the latest in the thick-cortex model, with the maximum stress of 96.4 Mpa, and the maximum stress was 89.7 Mpa in the middle cortex model.Conclusion The thickness of the intertrochanteric cortex may be a determinant in the types of hip fracture.