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.

Transient elastohydrodynamic lubrication analysis of ultra-high molecular weight polyethylene hip joint replacements

2001 ◽  
Vol 216 (4) ◽  
pp. 409-420 ◽  
Author(s):  
D Jalali-Vahid ◽  
Z M Jin
Keyword(s):  
Hip Joint ◽  
Numerical Procedure ◽  
Elastohydrodynamic Lubrication ◽  
Squeeze Film ◽  
Joint Replacements ◽  
Artificial Hip Joint ◽  
Artificial Hip ◽  
Minimum Film Thickness ◽  
Hip Joint Replacements ◽  
Ultra High Molecular Weight

The cyclic variation in both the load and speed experienced during walking was considered in an elastohydrodynamic lubrication (EHL) analysis for artificial hip joint replacements in this study. A general numerical procedure was developed to take both the entraining and squeeze-film actions into the solution of the Reynolds equation in the spherical ball-in-socket coordinate, simultaneously with the elasticity equation, using the Newton-Raphson method. The numerical procedure developed was then applied to an example of hip joint replacements employing an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup against either a metallic or ceramic femoral head under simplified cyclic load and speed conditions. The predicted minimum film thickness was found to stay remarkably constant, despite a large change in the angular velocity and the load. This was attributed to the combined effect of entraining and squeeze-film actions in generating, replenishing and maintaining the lubricating film in artificial hip joint replacements. Furthermore, it was pointed out that the average transient minimum film thickness predicted throughout one cycle was very close to that under quasi-static conditions based upon the average angular velocity and load.

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.

Determination of Lubricating Film Thickness for Permeable Hydrogel and Non-Permeable Polyurethane Layers Bonded to a Rigid Substrate with Articular Reference to Cushion form Hip Joint Replacements

1996 ◽  
Vol 210 (2) ◽  
pp. 89-93 ◽  
Author(s):  
G McClure ◽  
Z M Jin ◽  
J Fisher ◽  
B J Tighe
Keyword(s):  
Film Thickness ◽  
Hip Joint ◽  
Squeeze Film ◽  
Glycerol Solution ◽  
Polyurethane Elastomers ◽  
Joint Replacements ◽  
Lubricating Film ◽  
Theoretical Predictions ◽  
Hip Joint Replacements ◽  
Lubricating Film Thickness

The lubricating film thickness in a model of compliant layered bearings, using both permeable hydrogels and non-permeable polyurethane elastomers for total hip joint replacements, has been measured using optical interferometry, under both entraining and squeeze-film motion. The film thickness in the lubricated contact was measured for both water and a 40 per cent glycerol solution in water as a function of entraining velocity and squeeze-film time. The measured lubricating film thickness for the permeable hydrogel was compared to that of the non-permeable polyurethane elastomer and little difference was found when the lubricating film thickness was sufficiently large (greater than 150 nm). Comparison of the experimental results and the theoretical predictions based upon elastohydrodynamic lubrication analysis showed good agreement in the entraining experiments where the film thickness was greater than 150 nm. In the squeeze-film experiments the experimental measurements were greater than the theoretical predictions for all squeeze times due to the formation of a central pocket of fluid which was not predicted by the simple theory used. This also occurred for the hydrogels for films greater than 150 nm. For longer squeeze times the film thickness for the hydrogel fell below the theoretical prediction. This was considered to be due to the permeability of the hydrogel reducing the film thickness when the film thickness was less than 150 nm. The permeability of the hydrogel was not modelled in the theoretical lubrication analysis used in this study.

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

Prediction of lubricating film thickness in UHMWPE hip joint replacements

2001 ◽  
Vol 34 (2) ◽  
pp. 261-266 ◽  
Author(s):  
D. Jalali-Vahid ◽  
M. Jagatia ◽  
Z.M. Jin ◽  
D. Dowson
Keyword(s):  
Film Thickness ◽  
Hip Joint ◽  
Joint Replacements ◽  
Lubricating Film ◽  
Hip Joint Replacements ◽  
Lubricating Film Thickness

MAPPING OF LUBRICATING FILM THICKNESS IN HUMAN HIP JOINT REPLACEMENTS

2012 ◽  
Vol 2012 (04) ◽  
pp. 378-381 ◽  
Author(s):  
Dalibor Bosak ◽  
Jan Lastuvka ◽  
Martin Vrbka ◽  
Tomas Navrat ◽  
Martin Hartl ◽  
...  
Keyword(s):  
Film Thickness ◽  
Hip Joint ◽  
Joint Replacements ◽  
Lubricating Film ◽  
Hip Joint Replacements ◽  
Lubricating Film Thickness

Transient Elastohydrodynamic Lubrication of Hip Joint Implants

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Fengcai Wang ◽  
Zhongmin Jin
Keyword(s):  
Hip Joint ◽  
Elastohydrodynamic Lubrication ◽  
Squeeze Film ◽  
Acetabular Cup ◽  
Spherical Coordinate ◽  
Joint Implant ◽  
Lubrication Performance ◽  
Convolution Model ◽  
Flexion Extension ◽  
Joint Implants

A general transient elastohydrodynamic lubrication model was developed for artificial hip joint implants, particularly in which the three-dimensional time-dependent physiological load and motion components experienced during walking conditions were considered in the theoretical formulation, although only a predominantly vertical load combined with a flexion-extension motion was actually solved. A nominal ball-in-socket configuration was adopted to represent the articulation between the femoral head and the acetabular cup in both simplified and anatomical positions. An appropriate spherical coordinate system and the corresponding mesh grids were used in the general transient lubrication model. Additionally, an equivalent discrete spherical convolution model and the corresponding spherical fast Fourier transform technique were employed to facilitate the evaluation of elastic deformation of spherical bearing surfaces in hip joint implants. The general lubrication model was subsequently applied to investigate the transient lubrication performance of a typical metal-on-metal hip joint implant. The effects of both cup inclination angles in either anatomical or horizontally simplified positions and different lubricant viscosities on the transient elastohydrodynamic lubrication were analyzed under the predominant components of vertically dynamic loading and flexion-extension motion. It was found that the general lubrication model and the numerical methodology were efficient for the transient elastohydrodynamic lubrication analysis during walking condition in hip joint implants. Furthermore, the significant effect of squeeze-film action on maintaining and enhancing the total thin film thickness formation was discussed for the transient lubrication study of the typical hip joint implant.

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