scholarly journals COMPARISON OF TWO UNCEMENTED TRAPEZIO-METACARPAL CUPS: A FINITE ELEMENT STUDY

Hand Surgery ◽  
2013 ◽  
Vol 18 (02) ◽  
pp. 221-228 ◽  
Author(s):  
R. Thorkildsen ◽  
J. Theodorsson ◽  
M. Mellgren ◽  
M. Røkkum

Trapezium components from two uncemented total joint replacements were compared in a three-dimensional finite element model. A 100 N axial and angular load was applied in a normal and an osteoporotic bone model. The axial deformation and maximum periprosthetic stress are greater for the ElektraTM than the Motec CMC® cup. The Motec CMC® design is less sensitive to changing bone quality. The ElektraTM cup transmits more stress to the cortical bone rim in all load conditions, but under angular loading the proportionate increase in stress is lower. The Motec CMC® design distributes the stress and contact pressure more evenly, whereas the ElektraTM transfers most of the load to the cortical bone rim and the screw hole base. The design features that are believed to be of greatest significance for the differences are the raised centre of rotation of the Motec CMC® cup and the collar acting as a lever arm.

1986 ◽  
Vol 108 (2) ◽  
pp. 111-119 ◽  
Author(s):  
R. B. Little ◽  
H. W. Wevers ◽  
D. Siu ◽  
T. D. V. Cooke

A three-dimensional finite element model of the proximal tibia has been developed to provide a base line for further modeling of prosthetic resurfaced tibiae. The geometry for the model was developed by digitizing coronal and transverse sections made with the milling machine, from one fresh tibia of average size. The load is equally distributed between the medial and lateral compartments over contact areas that were reported in the literature. An indentation test has been used to measure the stiffness and the ultimate strength of cancellous bone in four cadaver tibiae. These values provided the statistical basis for characterising the inhomogeneous distribution of the cancellous bone properties in the proximal tibia. All materials in the model were assumed to be linearly elastic and isotropic. Mechanical properties for the cortical bone and cartilage have been taken from the literature. Results have been compared with strain gage tests and with a two-dimensional axisymmetric finite element model both from the literature. Qualitative comparison between trabecular alignment, and the direction of the principal compressive stresses in the cancellous bone, showed a good relationship. Maximum stresses in the cancellous bone and cortical bone, under a load which occurs near stance phase during normal gait, show safety factors of approximately eight and twelve, respectively. The load sharing between the cancellous bone and the cortical bone has been plotted for the first 40 mm distally from the tibial eminence.


2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.


2013 ◽  
Vol 336-338 ◽  
pp. 760-763
Author(s):  
Hui Yue

A short explanation of the finite element method as a powerful tool for mathematical modeling is provided, and an application using constitutive modeling of the behavior of ligaments is introduced. Few possible explanations of the role of water in ligament function are extracted from two dimensional finite element models of a classical ligament. The modeling is extended to a three dimensional finite element model for the human anterior cruciate ligament. Simulation of ligament force in pitching motion of basketball player is studied in this paper.


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