A Comparative Analysis of Different Treatments for Distal Femur Fractures using the Finite Element Method

Abstract

The main objective of this work is the evaluation, by means of the finite element method (FEM) of the mechanical stability and long-term microstructural modifications in bone induced to three different kinds of fractures of the distal femur by three types of implants: the Condyle Plate, the less invasive stabilization system plate (LISS) and the distal femur nail (DFN). The displacement and the stress distributions both in bone and implants and the internal bone remodelling process after fracture and fixation are obtained and analysed by computational simulation. The main conclusions of this work are that distal femoral fractures can be treated correctly with the Condyle Plate, the LISS plate and the DFN. The stresses both in LISS and DFN implant are high especially around the screws. When respect to remodelling, the LISS produces an important resorption in the fractured region, while the other two implants do not strongly modify bone tissue microstructure.

Subject-specific finite element models of long bones: An in vitro evaluation of the overall accuracy

“…The most recently published studies consider bone as an inhomogeneous material and derive its mechanical properties from the CT dataset, averaging the CT scalar field over each element volume using various algorithms (Huiskes et al, 1998;Keaveny and Bartel, 1993;Perillo-Marcone et al, 2003;. Until quite recently the majority of studies described bone as a homogeneous two phase material, deriving the mechanical properties of cortical and spongious bone from the literature (Spears et al, 2001;Verdonschot et al, 1993;Villarraga et al, 1999), a simplistic approach that has not been still completely abandoned (Cegonino et al, 2004). It is true that the adoption of an inhomogeneous model, often characterized by dozens, if not hundreds, of different material properties, may induce a large computational effort, particularly when performing non-linear simulations.…”

Mechanical competence of bone-implant systems can accurately be determined by image-based micro-finite element analyses

“…Hence, nearly all studies have simplified cortical and trabecular bone to homogeneous and isotropic linear elastic materials. Although such simplifications may be justified for the determination of non-local phenomena [14], the application of averaged bone properties for local analysis in highly heterogeneous and anisotropic cancellous bone may not be reasonable; instead, it seems appropriate that for cases like this the discrete nature of trabecular bone has to be taken into account. At present, only very few publications exist that do not model trabecular bone as a continuum in the bone-implant constructs [18].…”

“…Therefore computer simulations, finite element (FE) models in particular, have great potential to establish as an alternative for experimental biomechanical tests on bone-screw structures. FE analyses of bone-implant constructs have addressed phenomena at the apparent level, such as overall structural competence [13,14], as to get a better understanding of load distributions when using different kinds of implant configurations. Other FE models addressed the effects of screw design, and analyzed overall geometries, thread profiles and surfaces [15,16].…”

Mechanobiological Models for Bone Tissue. Applications to Implant Design

“…Cegoñino et al [74] also analyzed the mechanical stability and bone remodeling adaptation of several distal femoral fractures treated with an intramedullary nail (DFN: distal femoral nail) and with an extramedullary plate (LISS: less invasive stabilization system). Both types of implants achieve a correct stabilization of the fracture, while the LISS plate causes more resorption in the distal region, specifically in the fracture site, due to the bridge effect of the plate in this region.…”