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Time dependent flow of biolubricant and suspended particles behavior within total hip replacement
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. (Biotribology)
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Total hip replacement (THR) has been one of the most successful surgeries in the 21st century. Ultra-high-molecular-weight-polyethylene (UHMWPE) shows favorable mechanical and tribological properties when used as a bearing surface material in THR. However, produced UHMWPE wear particles challenge increasing the THR lifetimes. Bone loss (osteolysis) initiated by these wear particles is a major cause of total joint arthroplasty failure in both hip and knee prosthesis.

In addition to improving the wear resistance of bearing surfaces to reduce wear, wear debris distribution mechanisms within the joint gap must also be thoroughly investigated. These particles distribute within lubricant and across the implant gap. Synovial fluid (SF) lubricates natural joints which is a viscoelastic non-Newtonian shear thinning fluid. The non-Newtonian behavior of SF is attributed to its hyaluronic acid (HA) content which is a linear biopolymer. The distribution patterns of wear particles within total joint replacement are affected by the special rheological behaviors of the SF, geometrical parameters, particle size and shape distribution and particle-fluid interactions. Therefore, understanding wear particles distribution pattern is pivotal to understand the mechanism and eventually minimizing third-body wear of the UHMWPE acetabular liner in THR.

According to fluid mechanics forces, the size and density of wear particles suggests that wear particles follow lubricant movements. However, over a matter of hours, such particles show specific behaviors within viscoelastic fluid (not visible in Newtonian fluid) such as particle migration and string formation along the flow direction.

The main aim of this project was to develop and validate an experimental method for assessing characteristics of HA and artificial SF solutions and behaviors of wear particles in a viscoelastic fluid flow. The effects of different parameters such as HA concentration, protein content, fluid flow types (steady, unsteady, etc.) and gap shapes on fluid behavior were quantified to fully understand such mechanisms.

In this project, micro particle image velocimetry (micro-PIV) was applied as the quantitative flow visualization method. Pin-on-disk tribo-measurement was performed as a complimentary study to investigate the tribological behaviors of a UHMWPE pin rotating against a cobalt chromium molybdenum (CoCrMo) disk in the presence of HA solutions of various concentrations. This study was conducted to understand the effects of dynamic loading on lubricant performance relative to those of static loading.

The results showed that under oscillatory flow conditions, strain levels, rates, and distributions are important parameters that affect the flow behaviors of HA solutions. Particle migration and alignment were affected by channel sizes, HA concentrations, flow types and the elastic instability of the solution.

The tribological study results suggested that in the presence of HA, sinusoidal dynamic loading does not affect the frictional behaviors of UHMWPE moving against CoCrMo in comparison with static loading.

Place, publisher, year, edition, pages
Luleå University of Technology, 2017. , 94 p.
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
URN: urn:nbn:se:ltu:diva-61756ISBN: 978-91-7583-810-6 (print)ISBN: 978-91-7583-811-3 (electronic)OAI: oai:DiVA.org:ltu-61756DiVA: diva2:1070417
Public defence
2017-03-31, E231, Luleå, 13:00 (English)
Opponent
Supervisors
Available from: 2017-02-06 Created: 2017-02-01 Last updated: 2018-01-13Bibliographically approved
List of papers
1. Bio-lubricant flow behaviour in mini-channels
Open this publication in new window or tab >>Bio-lubricant flow behaviour in mini-channels
2016 (English)In: Lubrication Science, ISSN 0954-0075, E-ISSN 1557-6833, Vol. 28, no 4, 221-242 p.Article in journal (Refereed) Published
Abstract [en]

One of the most common causes of failures in total joint replacements is the generation of wear particles within the joint. This contributes to bone lost and aseptic loosening of the implant, eventually requiring its replacement. Many studies have been carried out to improve the wear characteristics of bearing surfaces in total joint replacement. From the lubrication point of view, the friction behaviour of surfaces and rheology of the joint lubricant (synovial fluid) have been extensively studied. However, little attention has been paid to the interaction between the lubricant and the bearing surfaces. The aim of this study is to develop a methodology for studying the behaviour of bio-based lubricant in mini-channels. For this purpose, micro-particle image velocimetry was used in order to characterise the lubricant behaviour. Channels made of relevant materials such as ultra-high molecular weight polyethylene, cobalt–chromium–molybdenum alloy and titanium–aluminium–vanadium alloy with 1 and 1.5 mm width, 45 mm length and 2 mm depth were experimentally investigated. Results suggested that the used polymeric solution interaction with solid surfaces is very sensitive to the polymer concentration in the lubricant. Moreover, it was observed that there exist differences between water (Newtonian reference fluid) and the polymeric solution behaviour even at very simple movements; although usually, the properties of this lubricant at high shear rates are estimated by water properties.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Fluid Mechanics and Acoustics
Research subject
Machine Elements; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-8713 (URN)10.1002/ls.1328 (DOI)000383722300003 ()73ea7014-caf1-42f2-9e3a-9f0595d1ee89 (Local ID)73ea7014-caf1-42f2-9e3a-9f0595d1ee89 (Archive number)73ea7014-caf1-42f2-9e3a-9f0595d1ee89 (OAI)
Note

Validerad; 2016; Nivå 2; 20160330 (alasaf)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-01-10Bibliographically approved
2. Viscoelastic behaviour effect of hyaluronic acid on reciprocating flow inside mini-channel
Open this publication in new window or tab >>Viscoelastic behaviour effect of hyaluronic acid on reciprocating flow inside mini-channel
2016 (English)In: Lubrication Science, ISSN 0954-0075, E-ISSN 1557-6833, Vol. 28, no 8, 521-544 p.Article in journal (Refereed) Published
Abstract [en]

One of the most successful surgeries during the 21st century is total joint replacement (TJR) with material combination of polymer-on-metal (PoM). Despite its success, wear particle generation at the interface of the polymer and metal causes eventually implant loosening. Investigating and understanding the wear particles distribution should help in designing implants with better performances. First step towards characterising wear particle distribution is deriving the lubricant behaviour and velocity distribution inside implant gap. Different hyaluronic acid (HA) solutions were subjected to a sinusoidal movement in straight rectangular channels. The velocity profiles along the channel width were measured with Micro Particle Image Velocimetry. HA solution behaviour was found to be dependent on the concentration. Results showed significant differences between the water (Newtonian) and HA behaviour in unsteady flow. The unsteady behaviour of the lubricant depended strongly on its non-Newtonian viscoelastic behaviour which was due to the time dependent nature of HA solution.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Fluid Mechanics and Acoustics
Research subject
Machine Elements; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-8598 (URN)10.1002/ls.1344 (DOI)000387584800003 ()2-s2.0-8499453037 (Scopus ID)71ddbd58-5181-435c-b427-8e4ed4292822 (Local ID)71ddbd58-5181-435c-b427-8e4ed4292822 (Archive number)71ddbd58-5181-435c-b427-8e4ed4292822 (OAI)
Note

Validerad; 2016; Nivå 2; 2016-11-25 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-01-10Bibliographically approved

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