Friction and wear mechanisms in hip prosthesis: Comparison of joint materials behaviour in several lubricants (original) (raw)
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Health and Technology, 2019
From an experimental point of view, determining the lubrication regime established between contact surfaces of joint prosthesis using the theory of elastohydrodynamic lubrication is rather impractical due to the intrinsic hindrances to measure the thickness of the lubricant film at the contact area. This claim is supported by the results obtained by experts using optical interferometry to perform such measurements using synovial like fluids. Similarly, research has shown that the complex rheology of the synovial fluid complicates the direct application of EHL theory and plays an important role in the lubrication mechanisms at work in prosthetic devices. Since the natural response of all tribological systems is the frictional force, rather than trying to measure the thickness of the lubricant film to determine the lubrication regime, we measured the effect of loading and entrainment on the friction coefficient at the contact point of an AISI 316L stainless steel sphere loaded against an ultra-high molecular weight polyethylene disc, lubricated with fetal bovine serum solution, at high values of slidingto-rolling ratio. Applying statistical analysis, we obtained a best-fit model that shows a smooth transition from mixed to full-film lubrication regime
Materials Science and Engineering: C, 2009
An accelerated wear testing procedure was developed to carry out an articulation process between UHWMPE and microfabricated surfaces with controlled asperities. By such a design, the effect of lubricant on wear of UHMWPE can be scaled-up and measured within a short duration of the test. The most abundant composition of the synovial fluid-human serum albumin was employed as a lubricant. Analysis of the albumin protein structure by a circular dichroism (CD) spectroscopy was proceeded to detect the conformational change during a tribological process. We observed that the thinner and fibril-like wear particles were found in biological lubricants than the particle generated in water. Our results also indicated that the content of α-helix structure of albumin was decreased after the tribological process. The denatured albumin solution resulted in the decrease of UHMWPE wear rate. It may be due to the decrease of the contact angle of unfolding albumin protein on articulating surfaces. It implies a larger coverage of the lubricating molecules on the UHMWPE surface. The relevance of the tribological process induced conformational change and wear of UHWMPE were discussed in this study.
Malaysian Journal of Medicine and Health Sciences, 2020
Introduction: The lubricant thickness in clearance between bearing surfaces for metallic hip implants are currently incapable of accommodating the motion experienced (high load and low entraining motion) in hip walking cycle. Thus, micro-dimpled surfaces were introduced onto surfaces of metallic acetabular cups to improve lubricant thickness. Micro-dimpled surface is a method of advanced surface improvement to increase the lubricant thickness in various tribological applications, such as hip implants. However, the application of micro-dimpled surfaces in hip implants has not yet been explored adequately. Therefore, this study aims to identify the influence of micro-dimpled depth on lubricant thickness elastohydrodynamically for metallic hip implants using Fluid-Structure Interaction (FSI) approach. Methods: Fluid-Structure Interaction (FSI) approach is an alternative method for analysing characteristics of lubrication in hip implant. Dimples of radius 0.25 mm and various depths of 5μm, 45μm and 100μm were applied on the cup surfaces. The vertical load in z-direction and rotation velocity around y-axes representing the average load and flexion-extension (FE) velocity of hip joint in normal walking were applied on Elastohydrodynamic lubrication (EHL) model. Results: The metallic hip implants with micro-dimpled surfaces provided enhanced lubricant thickness, namely by 6%, compared to non-dimpled surfaces. Furthermore, it was suggested that the shallow depth of micro-dimpled surfaces contributed to the enhancement of lubricant thickness. Conclusion: Micro-dimpled surfaces application was effective to improve tribological performances, especially in increasing lubricant thickness for metallic hip implants.
Adsorption of albumin on prosthetic materials: Implication for tribological behavior
2006
The orthopedic prosthesis used to substitute damaged natural joints are lubricated by a pseudosynovial fluid that contains biological macromolecules with potential boundary lubrication properties. Proteins are some of those macromolecules whose role in the lubrication process is not yet completely understood. In a previous work, we investigated the influence of the presence of albumin, the major synovial protein, upon the tribological behavior of three of the most used pairs of artificial joint materials: ultra high molecular weight polyethylene (UHMWPE) against counterfaces of alumina, CoCrMo alloy, and 316L stainless steel. Albumin was found to cause a significant decrease in the friction coefficient when the counterfaces were metallic because transfer of UHMWPE was avoided, but this effect was much weaker in the case of alumina. The objective of the present work was to look for an explanation for these differences in tribological behavior in terms of albumin adsorption. With this goal, studies on adsorption of bovine serum albumin (BSA) on the counterface materials, from a biological model fluid (Hanks' balanced salt solution), were carried out using radiolabeled albumin (125 I-BSA), X-ray photoelectron spectroscopy, and atomic force microscopy. The conclusion from all techniques is that the driving force for albumin adsorption is higher on the metals than on alumina. These results confirm that the greater the amount of protein adsorbed on the counterface, the more efficient is the protection against the transfer of polymeric film to the counterface.
Limitation of the Lubricating Ability of Total Hip Prostheses with Hard on Hard Sliding Material
Tribology Online, 2013
Recently, metal on metal hip prostheses have been revived following excellent clinical results. However, the risk of wear diseases has not been removed yet. Fluid film formation is necessary for long term reliability of a total hip prosthesis because solid contact of the prosthesis induces serious wear. However, the fluid film can be only formed under limited conditions together with an appropriate shape design. Radial clearance is also an important factor because the radius has an upper limit in the joint space. A radial clearance that is too small induces severe contact, whereas decreasing radial clearance enhances squeezed film formation. The most appropriate radial clearance currently remains unclear. We prepared some specimens with high accuracy of polishing, which were balls and cups of the Co-Cr-Mo alloy with a common radius of 16 mm and several radial clearances, 0.15-95.8 µm. Their lubricating ability was evaluated by a friction test using a pendulum machine. The frictional coefficient was a local minimum where the radial clearance was 20-30 µm. It was found that appropriate radial clearance of a total hip prosthesis with hard on hard material must exist within this range.
Biomaterials, 2009
The selectivity of synovial fluid protein adsorption onto ultra-high molecular weight polyethylene (UHMWPE) and alumina (Al 2 O 3 ), and in particular the ability of glycoproteins to adsorb in the presence of all the other synovial fluid proteins, was investigated by means of fluorescence microscopy and gel electrophoresis (SDS-PAGE). The non-specific nature of protein adsorption from synovial fluid indicated that the lubrication of artificial hip-joint materials may not be attributable to a single protein as has been frequently suggested. The friction behavior of polyethylene (PE) sliding against Al 2 O 3 in solutions of bovine serum albumin (BSA), alpha-1-acid glycoprotein (AGP) and alpha-1-antitrypsin (A1AT) was investigated by means of colloidal probe atomic force microscopy. BSA was shown to be a poorer boundary lubricant than the phosphate buffered saline used as a control. This was attributed to denaturation of the BSA upon adsorption, which provided a high-shear-strength layer at the interface, impairing the lubrication. Interestingly, both the glycoproteins AGP and A1AT, despite their low concentrations, improved lubrication. The lubricating properties of AGP and A1AT were attributed to adsorption via the hydrophobic backbone, allowing the hydrophilic carbohydrate moieties to be exposed to the aqueous solution, thus providing a low-shear-strength fluid film that lubricated the system. The amount of glycoprotein adsorbed on hydrophobic surfaces was determined by means of optical waveguide lightmode spectroscopy (OWLS), allowing conclusions to be drawn about the conformation of the glycan residues following adsorption.
Biomaterials, 2003
Hip simulator tests of femoral balls of cobalt-chromium alloy or zirconia against acetabular cups of UHMW polyethylene were run with and without a coolant circulated inside the femoral balls. Without cooling, the wear of polyethylene against zirconia was about 48% lower than with cobalt-chromium alloy, but the steady-state temperature of the zirconia ball was higher (55 degrees C vs. 41 degrees C), and there was more precipitation of protein from the serum, which sometimes formed an adherent layer on the surface of the zirconia. Circulating coolant at 1-20 degrees C markedly reduced the bearing temperatures and the protein precipitation. With coolant at 4 degrees C, wear of the polyethylene against cobalt-chromium alloy was about 26% lower than against zirconia, but the macroscopic and microscopic appearance of the worn polyethylene surfaces were unlike that typically generated in vivo. With or without coolant, the morphology of the polyethylene wear debris was comparable to that ge...
Friction behaviour of hydrophilic lubricious coatings for medical device applications
Tribology International, 2015
The friction behaviour of new chitosan derivative coatings obtained by chemical modification of chitosan with fatty acids (linoleic and dilinoleic acid) has been investigated in order to explore their potential as endovascular catheter coatings and to benchmark them against commercially available coatings used in endovascular catheter applications. An in vitro tribological system was developed that was intended to represent to a limited extent the in vivo tribological conditions of a typical endovascular catheterization procedure. Continuous reciprocating sliding tests were carried out with uncoated and coated polymer specimens. The results showed that all of the coatings tested decreased the coefficient of friction compared to the uncoated polymer. Compared to a neat chitosan coating, the chitosan derivative coatings showed a clear reduction in the coefficient of friction to levels similar to those of the commercially-available coatings. A comparison between the friction results and contact angle measurements carried out on the coatings indicated that a range of contact angle values exists for which the friction coefficient is at a minimum. The reason for this is unclear and further studies are required in order to confirm and investigate the trend, especially within the context of hydrophilic lubricious coating development. .pl (A. Niemczyk), mirfray@zut.edu.pl (M. El Fray), s.e.franklin@philips.com (S.E. Franklin). Please cite this article as: Niemczyk A, et al. Friction behaviour of hydrophilic lubricious coatings for medical device applications. Tribology International (2015), http://dx.
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2008
Lubrication modelling is of great importance in the design of artificial hip joints, especially for the demand of long life expectancy of those joints employing a metal-on-metal bearing. Through lubrication analysis, the dimensions of the head/cup and the clearance between them can be reasonably determined, and thus, if fluid film lubrication can be generated in artificial hip joint replacements, the wear and related failure can be reduced. In the majority of published numerical studies of the lubrication of hip joints, the synovial fluid for the natural joint and bovine serum used for in vitro simulator testing of joint replacements have always been treated as isoviscous, incompressible Newtonian fluids because the viscosity of these lubricants is almost unchanged at high shear rate. However, all these biological lubricants generally exhibit non-Newtonian characteristics of shear thinning, particularly under relatively low shear rates, and display a second Newtonian plateau at high shear rates.