Effect of Acetabular Cup Position on the Contact Mechanics of Ceramic-on-Ceramic Hip Joint Replacements

2003 ◽  
Vol 254-256 ◽  
pp. 639-642 ◽  
Author(s):  
M.M. Mak ◽  
Z.M. Jin
Keyword(s):  
Contact Mechanics ◽  
Hip Joint ◽  
Acetabular Cup ◽  
Joint Replacements ◽  
Hip Joint Replacements ◽  
Cup Position ◽  
Acetabular Cup Position ◽  
Ceramic On Ceramic

Elastohydrodynamic lubrication analysis of ultra-high molecular weight polyethylene hip joint replacements under squeeze-film motion

2001 ◽  
Vol 215 (2) ◽  
pp. 141-151 ◽  
Author(s):  
M Jagatia ◽  
D Jalali-Vahid ◽  
Z M Jin
Keyword(s):  
Molecular Weight ◽  
Femoral Head ◽  
Film Thickness ◽  
Hip Joint ◽  
Elastohydrodynamic Lubrication ◽  
Squeeze Film ◽  
Acetabular Cup ◽  
Joint Replacements ◽  
Hip Joint Replacements ◽  
Ultra High Molecular Weight

Elastohydrodynamic lubrication was analysed under squeeze-film or normal approach motion for artificial hip joint replacements consisting of an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup and a metallic or ceramic femoral head. A simple ball-in-socket configuration was adopted to represent the hip prosthesis for the lubrication analysis. Both the Reynolds equation and the elasticity equations were solved simultaneously for the lubricant film thickness and hydrodynamic pressure distribution as a function of the squeeze-film time was solved using the Newton-Raphson method. The elastic deformation of the UHMWPE cup was calculated by both the finite element method and a simple equation based upon the constrained column model. Good agreement of the predicted film thickness and pressure distribution was found between these two methods. A simple analytical method based upon the Grubin -Ertel-type approximation developed by Higginson in 1978 [1] was also applied to the present squeeze-film lubrication problem. The predicted squeeze-film thickness from this simple method was found to be remarkably close to that from the full numerical solution. The main design parameters were the femoral head radius, the radial clearance between the femoral head and the acetabular cup, and the thickness and elastic modulus for the UHMWPE cup; the effects of these parameters on the squeeze-film thickness generated in current hip prostheses were investigated.

scholarly journals Running-in friction of hip joint replacements can be significantly reduced: The effect of surface-textured acetabular cup

Friction ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 1137-1152
Author(s):  
David Nečas ◽  
Hatsuhiko Usami ◽  
Tatsuya Niimi ◽  
Yoshinori Sawae ◽  
Ivan Křupka ◽  
...  
Keyword(s):  
Hip Joint ◽  
Acetabular Cup ◽  
Joint Replacements ◽  
Hip Joint Replacements ◽  
Effect Of Surface

A general axisymmetric contact mechanics model for layered surfaces, with particular reference to artificial hip joint replacements

2000 ◽  
Vol 214 (5) ◽  
pp. 425-435 ◽  
Author(s):  
Z M Jin
Keyword(s):  
Contact Mechanics ◽  
Hip Joint ◽  
Joint Replacements ◽  
Total Hip ◽  
Mechanics Model ◽  
Artificial Hip Joint ◽  
Metal On Metal ◽  
Artificial Hip ◽  
Hip Joint Replacements ◽  
Joint Prostheses

A general axisymmetric contact mechanics model for layered surfaces is considered in this study, with particular reference to artificial hip joint replacements. The indenting surface, which represents the femoral head, was modelled as an elastic solid with or without coating, while the other contacting surface, which represents the acetabular cup, was modelled as a two-layered solid. It is shown that this model is applicable to current total hip joint prostheses employing ultra-high molecular weight polyethylene (UHMWPE) acetabular cups against metallic, metallic with coating or ceramic femoral heads as well as metal-on-metal combinations. The effect of cement is also investigated for these prostheses using this model. The use of a metallic bearing surface bonded to a UHMWPE substrate for acetabular cups is particularly examined for metal-on-metal hip joint replacements. Both the contact radius and the contact pressure distribution are predicted for examples of these total hip joint replacements, under typical conditions. Application of contact mechanics to the design of artificial hip joint replacements employing various material combinations is discussed.

Simulation: Problems Relating to Mechanical Tests on Hip Joint Replacements

1980 ◽  
Vol 9 (1) ◽  
pp. 17-22
Author(s):  
A M Gatti
Keyword(s):  
Hip Joint ◽  
Ceramic Materials ◽  
Mechanical Tests ◽  
Acetabular Cup ◽  
Joint Replacements ◽  
Wear And Friction ◽  
The Coefficient Of Friction ◽  
Low Wear ◽  
Hip Joint Replacements ◽  
Joint Prostheses

In hip joint prostheses, one of the problems is the choice of mating materials. In fact the coefficient of friction between the cup surface and the surface of the head should be very small in order to minimize any tendency towards loosening related to friction torques on the cup. A low wear coefficient is also desirable to provide maximum life of the acetabular cup. Failures of some types of hip joint prostheses with respect to these parameters induced us to carry out a series of simulation tests. For evaluation of these mating materials as to wear and friction, two different lines of investigation were followed. The work considers two different cases relating to results obtained by several authors. From the analysis of the different hip joint simulators we have concluded that (i) it is not possible to compare results, (ii) there are even non-suitable simulators, and (iii) the few suitable simulators can also be used in order to obtain an improved surface finish (especially for ceramic materials), before the implantation.

A full numerical analysis of hydrodynamic lubrication in artificial hip joint replacements constructed from hard materials

1999 ◽  
Vol 213 (4) ◽  
pp. 355-370 ◽  
Author(s):  
Z. M. Jin ◽  
D Dowson
Keyword(s):  
Film Thickness ◽  
Hip Joint ◽  
Hydrodynamic Lubrication ◽  
Squeeze Film ◽  
Radial Clearance ◽  
Acetabular Cup ◽  
Joint Replacements ◽  
Lubricating Film ◽  
Metal On Metal ◽  
Hip Joint Replacements

A full numerical analysis of the hydrodynamic lubrication problem of artificial hip joint replacements with surfaces of high elastic modulus materials, such as metal-on-metal or ceramic-on-ceramic, under cyclic walking conditions is reported in this paper. The Reynolds equation in spherical coordinates has been solved for both entraining and combined entraining and squeeze film motions under a three-dimensional variation in both the load and the speed experienced in hip joints during walking. It has been shown that a finite lubricating film thickness can be developed during the walking cycle owing to the combined action of the squeeze film and entraining motions under some conditions. It has been found that the design parameters for plain spherical bearings, such as the femoral head radius and the radial clearance between the femoral head and the acetabular cup, have a large effect on the magnitude of the predicted lubricating film thickness. Some interest has been shown in recent years in the performance of metal-on-metal bearings in which a dimple has been machined at the pole of the acetabular cup. It is shown that a dimple on the acetabular cup can significantly increase the film thickness throughout the walking cycle, particularly for relatively large depths and if the location of the dimple coincides with the direction of the resultant force acting on the joints. It is concluded that there is a good possibility that a full continuous hydrodynamic lubricating film can be developed in ceramic-on-ceramic hip joint replacements, and perhaps for some well-finished metal-on-metal implants with a relatively small radial clearance. For some metal-on-metal configurations, the effect of elastic deformation of the bearing surfaces must be taken into account in the lubrication analysis, particularly for a relatively large radial clearance.

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