Finite Element Analysis Applied to Bone Remodelling in Revision Arthroplasty of the Femur using Morselized Allograft and Cement

1998 ◽  
Vol 8 (2) ◽  
pp. 51-61 ◽  
Author(s):  
J.P. Simon ◽  
J. Vander Sloten ◽  
R. Van Audekercke ◽  
G. Van Der Perre ◽  
R.S.M. Ling ◽  
...  
Keyword(s):  
Finite Element ◽  
Revision Arthroplasty ◽  
Bone Allograft ◽  
Equivalent Thickness ◽  
Element Analysis ◽  
Bone Allografts ◽  
Small Influence ◽  
Morselized Allograft ◽  
Optimal Material ◽  
Uncemented Total Hip Replacement

Finite element models have extensively been developed and reported for primary cemented and uncemented total hip replacement, but not for revision arthroplasty of the hip. A two-dimensional equivalent thickness model was developed of the proximal femur with bone grafts, a thin but uniform cement layer and a standard femoral component. This model represents the reconstructed femoral revision setting described by Gie et al (1). The effects of surface texture, cement-stem friction, cement creep and stem malplacement were evaluated. Within the range of coefficients of friction which was investigated in this study (0.03, 0.136 and 0.3) it was observed that the influence of the value of the coefficient upon the stresses in the bone-implant structure are less than 5%. Also static cement creep and certain stem malalignments which were simulated showed a relatively small influence upon the stress distribution within this structure. An agreement between trabecular orientations in the remodeled bone allograft and the principal stress orientations in this structure was observed in the calcar region. It was concluded that the remodelling which occurs in the bone allografts follows Wolff's law of optimal material use in the trabecular structure.

Load Distribution in Barefoot Running Shoes

2015 ◽  
Author(s):  
Raoul Gnagne ◽  
Fred Barez ◽  
James Kao ◽  
Amer El-Hage
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Load Distribution ◽  
Ancient Greece ◽  
Maximum Compressive Stress ◽  
Equivalent Thickness ◽  
Element Analysis ◽  
Barefoot Running ◽  
Running Shoes ◽  
Olympic Sport

Running is one of the most practiced sports around the world and it dates back to Ancient Greece. Running became an Olympic sport in 1896 and today is mostly performed for fun and to stay in shape. Nowadays, athletic shoe companies make claims on the performance of the type of shoes they manufacture. Some of their claims include shoes that allow free movements, fit like a glove, and are in complete harmony with human mechanics. The preceding characteristics are those of so-called barefoot running shoes. Robillard [1] explains that minimalist running shoes could be defined as those that provide limited or no support and only minimal protection, with the heel at the same level as the forefoot. Even though running may have been investigated, however, there is not enough analyses on barefoot running shoes. The objective of this study was to investigate the load distribution on the feet of a healthy running adult wearing barefoot shoes through experimental work and finite element analysis (FEA). The methodology used in this study included experimental as well FEA. Tests were conducted with a 175-lb adult subject wearing a pair of minimalist shoes. Experimental data were collected and used to perform Finite Element Analysis. The barefoot shoes were modeled with an equivalent thickness of 0.453 inch, and the following parameters were experimentally determined such as the Young’s modulus of 467 psi, a density of 0.0025 lb/in3, and a Poisson’s ratio of 0.08. The simulation results yielded a maximum compressive stress of 38.71 psi in the toe region. This stress level was approximately one-half of the stresses generated in the heel region of conventional sport shoes. This study, further, revealed the reduction of stresses at the heel region with barefoot shoes resulting in lower risk of pain and injury to the foot in the absence of impact transients ordinarily experienced with conventional shoes.

Finite element analysis of the constrained Dirichlet boundary control problem governed by the diffusion problem

2020 ◽  
Vol 26 ◽  
pp. 78
Author(s):  
Thirupathi Gudi ◽  
Ramesh Ch. Sau
Keyword(s):  
Finite Element ◽  
Control Problem ◽  
Dirichlet Boundary ◽  
A Priori ◽  
Diffusion Problem ◽  
Discrete Control ◽  
Optimal Order ◽  
Control Constraints ◽  
Element Analysis ◽  
Dirichlet Boundary Control

We study an energy space-based approach for the Dirichlet boundary optimal control problem governed by the Laplace equation with control constraints. The optimality system results in a simplified Signorini type problem for control which is coupled with boundary value problems for state and costate variables. We propose a finite element based numerical method using the linear Lagrange finite element spaces with discrete control constraints at the Lagrange nodes. The analysis is presented in a combination for both the gradient and the L2 cost functional. A priori error estimates of optimal order in the energy norm is derived up to the regularity of the solution for both the cases. Theoretical results are illustrated by some numerical experiments.

Sign in / Sign up

Export Citation Format

Share Document