Finite element analysis on longitudinal and radial functionally graded femoral prosthesis

Abstract

This study focused on developing a 3D finite element model of functionally graded femoral prostheses to decrease stress shielding and to improve total hip replacement performance. The mechanical properties of the modeled functionally graded femoral prostheses were adjusted in the sagittal and transverse planes by changing the volume fraction gradient exponent. Prostheses with material changes in the sagittal and transverse planes were considered longitudinal and radial prostheses, respectively. The effects of cemented and noncemented implantation methods were also considered in this study. Strain energy and von Mises stresses were determined at the femoral proximal metaphysis and interfaces of the implanted femur components, respectively. Results demonstrated that the strain energy increased proportionally with increasing volume fraction gradient exponent, whereas the interface stresses decreased on the prostheses surfaces. A limited increase was also observed at the surfaces of the bone and cement. The periprosthetic femur with a noncemented prosthesis exhibited higher strain energy than with a cemented prosthesis. Radial prostheses implantation displayed more strain energy than longitudinal prostheses implantation in the femoral proximal part. Functionally graded materials also increased strain energy and exhibited promising potentials as substitutes of conventional materials to decrease stress shielding and to enhance total hip replacement lifespan.

Finite element study of functionally graded porous femoral stems incorporating body‐centered cubic structure

“…Therefore, the highest level of stress shielding is depicted due to the highest stiffness of this stem. Conversely, HGP and FGP stems yielded higher stress transfer to the bone in all the Gruen zones, and hence offered less stress shielding . Another important observation is that the stress values are almost identical in the distal end of the femur (Gruen zone 4) for all the tested stems (around 30 MPa).…”

“…The advantage of FGM is to tailor and control the mechanical properties of the stem to match the surrounding bone . Oshkour et al have conducted a finite‐element analysis on functionally graded femoral stems in the longitudinal and radial directions. The results have shown that increasing the grading exponent has led to an increase in the strain energy experienced by the bone, hence less stress‐shielding effect.…”

“…3,4 The stems are usually made of biocompatible materials such as Ti alloy, cobalt chromium (CoCr) alloy, or carbon-fiber-reinforced polyether ether ketone (CFR-PEEK) composite. 5,6 The mismatch between the stiffness of the dense stem (100-240 GPa) and the femur bone (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) results in the stem carrying most of the body weight, thus leading to aseptic loosening, shielding the femur bone from stresses, and bone resorption. 3,5 Stems of different geometrical designs have been proposed to overcome the issue of stress shielding.…”

Lattice Structures and Functionally Graded Materials Applications in Additive Manufacturing of Orthopedic Implants: A Review

“…[95] [104,105] for the femoral component of a knee through functionally graded composition. Three different material combinations were suggested: titanium, cobalt chromium, and hydroxyapatite.…”

A Hertzian Integrated Contact Model of the Total Knee Replacement Implant for the Estimation of Joint Contact Forces

“…It is important to emphasize that the knee contact force behaviors are activity-specific and the optimal design of the TKR may lead to maximizing the clinical outcomes. However, the implant design may be optimized when its effect on the musculoskeletal tissues and structures could be elucidated [5]. Joint contact forces play an important role in the understanding of the effect of the implant on the joint behavior and musculoskeletal load [6].…”