Finite element analysis of the impact of screw insertion distal to the trochanter minor on the risk of iatrogenic subtrochanteric fracture

Abstract

Iatrogenic subtrochanteric fractures are rarely encountered after cannulated screw fixation of femoral neck fractures; however, when they do occur, there can be several complications. Many orthopedic surgeons have concerns about the potential for iatrogenic subtrochanteric fractures after screw fixation distal to the trochanter minor; therefore, some surgeons are typically reluctant to perform this procedure. This study focused on the risk of an iatrogenic subtrochanteric fracture after treating femoral neck fractures with cannulated screws. The main purpose of the study was to understand iatrogenic subtrochanteric fractures and evaluate the effects on these fractures of an inverted triangular-shaped configuration for placement of the cannulated screws. A femur bone with an femoral neck fracture at a 40° incline to the horizontal plane was generated along with a representation of a three-dimensional finite element model, and three inverted triangular-shaped configurations for placement of the cannulated screws were investigated using finite element analyses. Statistical results indicated that the occurrence risk of ISF increases when the screw is located distal to the trochanter minor. Moreover, the risk of occurrence of intertrochanteric fracture increases when the screw is located medial to the trochanter minor because of local concentrated stress on the surface of the screw canals. To avoid the vulnerability of the subtrochanteric region, it was found that proximal placement of the screws using the inverted triangular-shaped configuration could yield better results. In addition, the results of this study provide suggestions on improved screw configurations.

Performance Assessment of Biocompatible Metals Used in the Treatment of Femoral Neck Fractures

“…Particularly, the number of computer-based studies using the finite-element method (FEM) has increased considerably. 20 In the numerical modeling approach based on the finite-element method in this study, femur bone and internal fixation implants were modeled using a general-purpose finite-element software, ANSYS Workbench. 21 Solid186 elements, which have 20 nodes and 3 degrees of freedom per node, were used and tetrahedral element shape was preferred.…”

“…In recent years, it has become common to use many different intellectual computer models together with the developing computer technologies and to develop solutions to different problems through numerical modeling techniques. Particularly, the number of computer-based studies using the finite-element method (FEM) has increased considerably . In the numerical modeling approach based on the finite-element method in this study, femur bone and internal fixation implants were modeled using a general-purpose finite-element software, ANSYS Workbench .…”

Tratamiento de las fracturas de cuello femoral con osteosíntesis. Diez claves para el éxito

“…Sensoz y cols. 32 hicieron un análisis finito de los elementos para evaluar las complicaciones relacionadas con un punto de entrada, y mostraron que la colocación de tornillos por debajo del trocánter menor aumenta significativamente las posibilidades de generar una fractura subtrocantérica.…”

Finite element analysis of a new internal fixation implant for Pauwels type III femoral neck fractures

“…According to the contact method described in previous studies [20][21][22] , contact binding was created between the internal xation screw and the femur, and friction contact was added to the fracture surface, with a friction coe cient of 0.46.…”