The effect of aspherical geometry and surface texturing on the elastohydrodynamic lubrication of metal-on-metal hip prostheses under physiological loading and motions

2010 ◽  
Vol 224 (12) ◽  
pp. 2627-2636 ◽  
Author(s):  
L M Gao ◽  
Q E Meng ◽  
F Liu ◽  
J Fisher ◽  
Z M Jin
Keyword(s):  
Hip Replacement ◽  
Numerical Solutions ◽  
Surface Texturing ◽  
Elastohydrodynamic Lubrication ◽  
Bearing Surface ◽  
Wear Rates ◽  
Physiological Loading ◽  
Metal On Metal ◽  
Head Surface ◽  
Lubrication Performance

As an alternative material combination, metal-on-metal (MOM) hip replacement has attracted a revived interest due to its very low wear rates. In this article, an elastohydrodynamic lubrication analysis is performed for an MOM hip replacement with specific geometrical designs: a macro Alpharabola geometry of the cup bearing surface and micro-dimples on the head surface. The corresponding numerical methodology is presented and full numerical solutions are obtained. The effect of the macro- and micro-geometrical designs on the lubrication performance is investigated, under both simplified and physiological walking conditions. The real physiological loading and motion conditions are important to be considered when optimizing the conformity-associated geometry of hip bearings. The Alpharabola geometry of cup bearing surface is found to significantly improve the lubricating film thickness and reduce hydrodynamic pressure of MOM hip implants, when the Alpharabola minimum radius is aligned with the loading direction. Dimpled surface texturing has an adverse effect in a fluid film lubrication regime under the conditions considered in this study.

scholarly journals Contact mechanics and elastohydrodynamic lubrication in a novel metal-on-metal hip implant with an aspherical bearing surface

2010 ◽  
Vol 43 (5) ◽  
pp. 849-857 ◽  
Author(s):  
Qingen Meng ◽  
Leiming Gao ◽  
Feng Liu ◽  
Peiran Yang ◽  
John Fisher ◽  
...  
Keyword(s):  
Contact Mechanics ◽  
Elastohydrodynamic Lubrication ◽  
Bearing Surface ◽  
Hip Implant ◽  
Metal On Metal

scholarly journals The hidden costs of metal-on-metal hip resurfacing: the financial and logistical implications of a change in hospital follow-up policy

2013 ◽  
Vol 95 (3) ◽  
pp. 88-91
Author(s):  
J Lloyd ◽  
I Starks ◽  
T Wainwright ◽  
R Middleton
Keyword(s):  
Hip Replacement ◽  
Hip Resurfacing ◽  
Surface Wear ◽  
Bearing Surface ◽  
Total Hip ◽  
Total Hip Replacements ◽  
Large Head ◽  
Metal On Metal ◽  
Hip Replacements

Metal-on-metal (MoM) hip resurfacings (HRs) and large head total hip replacements (LHTHRs) were perceived by many as a surgical revolution, with clear advantages over the traditional metal-on-polyethylene total hip replacement (THR). This is especially the case for younger, active individuals in whom conventional THR has been associated with higher rates of aseptic loosening. In addition to less bearing surface wear, frequently cited advantages for HR include the preservation of femoral bone stock, lower dislocation rates, and superior function and activity scores.

An improved TEHL analysis of textured roller bearings consider various texture parameters and slip

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Junning Li ◽  
Ka Han ◽  
Wuge Chen ◽  
Xiaojie Tang ◽  
Qian Wang
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Contact Area ◽  
Surface Texturing ◽  
Elastohydrodynamic Lubrication ◽  
Content Type ◽  
Roller Bearings ◽  
Texture Parameters ◽  
Lubrication Performance ◽  
Texture Size

Purpose The purpose of this study is to reveal the lubrication performance of textured roller bearings under various texture size, texture depth, texture types and slip. Design/methodology/approach In the present study, the improved thermal elastohydrodynamic lubrication method based on the surface texturing of the textured roller bearings is proposed, and then the effect of texture size, texture depth, texture types and slip on the contact pressure, film thickness and temperature distribution are analyzed systematically. Findings The results show that the pressure decreases and the film thickness increases on the contact area because of the surface texturing. The temperature increases first and then decreases as the texture size increases, and then the temperature increases as the texture depth and the slip increases. Compared to circle and square texture, cross texture can obviously decrease the temperature on the contact area. The effectiveness of the proposed method is verified. Originality/value This study can help to reduce friction and wear of textured roller bearings. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2020-0318/

Effect of Wear of Bearing Surfaces on Elastohydrodynamic Lubrication of Metal-on-Metal Hip Implants

2005 ◽  
Vol 219 (5) ◽  
pp. 319-328 ◽  
Author(s):  
F Liu ◽  
Z M Jin ◽  
F Hirt ◽  
C Rieker ◽  
P Roberts ◽  
...  
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Linear Wear ◽  
Wear Depth ◽  
Hip Implants ◽  
Bearing Surface ◽  
Lubricant Film Thickness ◽  
Hip Simulator ◽  
Metal On Metal

The effect of geometry change of the bearing surfaces owing to wear on the elastohydrodynamic lubrication (EHL) of metal-on-metal (MOM) hip bearings has been investigated theoretically in the present study. A particular MOM Metasul™ bearing (Zimmer GmbH) was considered, and was tested in a hip simulator using diluted bovine serum. The geometry of the worn bearing surface was measured using a coordinate measuring machine (CMM) and was modelled theoretically on the assumption of spherical geometries determined from the maximum linear wear depth and the angle of the worn region. Both the CMM measurement and the theoretical calculation were directly incorporated into the elastohydrodynamic lubrication analysis. It was found that the geometry of the original machined bearing surfaces, particularly of the femoral head with its out-of-roundness, could lead to a large reduction in the predicted lubricant film thickness and an increase in pressure. However, these non-spherical deviations can be expected to be smoothed out quickly during the initial running-in period. For a given worn bearing surface, the predicted lubricant film thickness and pressure distribution, based on CMM measurement, were found to be in good overall agreement with those obtained with the theoretical model based on the maximum linear wear depth and the angle of the worn region. The gradual increase in linear wear during the running-in period resulted in an improvement in the conformity and consequently an increase in the predicted lubricant film thickness and a decrease in the pressure. For the Metasul™ bearing tested in an AMTI hip simulator, a maximum total linear wear depth of approximately 13 μm was measured after 1 million cycles and remained unchanged up to 5 million cycles. This resulted in a threefold increase in the predicted average lubricant film thickness. Consequently, it was possible for the Metasul™ bearing to achieve a fluid film lubrication regime during this period, and this was consistent with the minimal wear observed between 1 and 5 million cycles. However, under adverse in vivo conditions associated with start-up and stopping and depleted lubrication, wear of the bearing surfaces can still occur. An increase in the wear depth beyond a certain limit was shown to lead to the constriction of the lubricant film around the edge of the contact conjunction and consequently to a decrease in the lubricant film thickness. Continuous cycles of a running-in wear period followed by a steady state wear period may be inevitable in MOM hip implants. This highlights the importance of minimizing the wear in these devices during the initial running-in period, particularly from design and manufacturing points of view.

Isoviscous elastohydrodynamic lubrication of circular point contacts with particular reference to metal-on-metal hip implants

2003 ◽  
Vol 217 (5) ◽  
pp. 397-402 ◽  
Author(s):  
D Jalali- Vahid ◽  
Z. M. Jin ◽  
D Dowson
Keyword(s):  
Numerical Solutions ◽  
Elastohydrodynamic Lubrication ◽  
Hip Implants ◽  
Point Contacts ◽  
Hip Joints ◽  
Circular Point ◽  
Metal On Metal ◽  
Artificial Hip Joints

A full numerical analysis of elastohydrodynamic lubrication (EHL) of circular point contacts was carried out in the present study under isoviscous conditions with particular reference to metal-on-metal artificial hip joints, using a modified Newton-Raphson method. It was found to be possible to incorporate directly the physiological conditions, representative of typical metal-on-metal hip implants under in-vivo walking or in-vitro simulator testing, in the present numerical solutions. The predicted minimum and central film thicknesses were compared favourably with those estimated from various formulae available in the literature. In particular, it was shown that both the minimum and the central film thickness expressions derived by Hamrock and Dowson were reasonably accurate for all the conditions considered in the present study.

Wear Simulation of Metal on Metal Hip Replacements: An Analytical Approach

2012 ◽  
Author(s):  
Lorenza Mattei ◽  
Francesca Di Puccio ◽  
Enrico Ciulli
Keyword(s):  
Hip Replacement ◽  
Experimental Tests ◽  
Wear Model ◽  
Wear Rates ◽  
Metal On Metal ◽  
Hip Replacements ◽  
Wear Law ◽  
Implant Wear

Hip replacement failure is mainly attributable to the implant wear. Consequently preclinical wear evaluations are extremely important. As experimental tests are attractive but highly cost/time demanding, several predictive models have been proposed mainly based on finite element simulations and for metal on plastic (MoP) implants. The aim of this study is to develop a mathematical wear model of metal on metal prostheses, revision of the previous one for MoP implants, developed by the same authors. The model, based on the Archard wear law and on the Hertzian theory, was applied to compare a total (THR) and a resurfacing (RHR) hip replacement under both in vivo and in vitro gait conditions. The results were in agreement with the literature predicting wear rates significantly higher for the RHR than for the THR. The effect of the boundary conditions on wear rates/maps was also investigated and the model limitations discussed.

Effect of surface texturing on the elastohydrodynamic lubrication analysis of metal-on-metal hip implants

2010 ◽  
Vol 43 (10) ◽  
pp. 1851-1860 ◽  
Author(s):  
Leiming Gao ◽  
Peiran Yang ◽  
Ian Dymond ◽  
John Fisher ◽  
Zhongmin Jin
Keyword(s):  
Surface Texturing ◽  
Elastohydrodynamic Lubrication ◽  
Hip Implants ◽  
Metal On Metal ◽  
Effect Of Surface
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