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Molecular Dynamics Investigation of Hyaluronan in Biolubrication. Polymers (Basel) 2022; 14:polym14194031. [PMID: 36235979 PMCID: PMC9571324 DOI: 10.3390/polym14194031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/06/2022] [Accepted: 09/07/2022] [Indexed: 11/17/2022] Open
Abstract
Aqueous solution of strongly hydrophilic biopolymers is known to exhibit excellent lubrication properties in biological systems, such as the synovial fluid in human joints. Several mechanisms have been proposed on the biolubrication of joints, such as the boundary lubrication and the fluid exudation lubrication. In these models, mechanical properties of synovial fluid containing biopolymers are essential. To examine the role of such biopolymers in lubrication, a series of molecular dynamics simulations with an all-atom classical force field model were conducted for aqueous solutions of hyaluronan (hyaluronic acid, HA) under constant shear. After equilibrating the system, the Lees-Edwards boundary condition was imposed, with which a steady state of uniform shear flow was realized. Comparison of HA systems with hydrocarbon (pentadecane, PD) solutions of similar mass concentration indicates that the viscosity of HA solutions is slightly larger in general than that of PDs, due to the strong hydration of HA molecules. Effects of added electrolyte (NaCl) were also discussed in terms of hydration. These findings suggest the role of HA in biolubirication as a load-supporting component, with its flexible character and strong hydration structure.
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Squeeze-film properties of synovial fluid and hyaluronate-based viscosupplements. Biomech Model Mechanobiol 2021; 20:1919-1940. [PMID: 34213668 DOI: 10.1007/s10237-021-01485-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/23/2021] [Indexed: 10/21/2022]
Abstract
The rheological properties of synovial fluid and hyaluronate (HA) solutions have been studied using a variety of viscometers and rheometers. These devices measure the viscosity of the fluid's resistance to shearing forces, which is useful when studying the lubrication and frictional properties of movable joints. Less commonly used is a squeeze-film fluid test, mechanistically similar to when two joint surfaces squeeze interposed fluid. In our study, we used squeeze-film tests to determine the rheological response of normal bovine synovial fluid and 10 mg/ml HA-based solutions, Hyalgan/Hyalovet, commercially available 500-700 kDa HA viscosupplements, and a 1000 kDa sodium hyaluronate (NaHy) solution. We found similar rheological responses (fluid thickness, viscosity, viscosity-pressure relationship) for all three fluids, though synovial fluid's minimum squeeze-film thickness was slightly thicker. Squeeze-film loading speed did not affect these results. Different HA concentrations and molecular weights also did not have a significant or consistent effect on the squeeze-film responses. An unexpected result for the HA-solutions was a linear increase in minimum fluid-film thickness with increasing initial fluid-film thickness. This result was attributed to faster gelling of thicker HA-solutions, which formed at a lower squeeze-film strain and higher squeeze-film strain rate compared to thinner layers. Also included is a review of the literature on viscosity measurements of synovial fluid and HA solutions.
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Yarimitsu S, Ito K, Fujie H. Influence of collagen fibre orientation on the frictional properties of articular cartilage. BIOSURFACE AND BIOTRIBOLOGY 2021. [DOI: 10.1049/bsb2.12005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Seido Yarimitsu
- Graduate School of Systems Design Tokyo Metropolitan University Hachioji Tokyo Japan
| | - Kei Ito
- Graduate School of Systems Design Tokyo Metropolitan University Hachioji Tokyo Japan
| | - Hiromichi Fujie
- Graduate School of Systems Design Tokyo Metropolitan University Hachioji Tokyo Japan
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Lin W, Klein J. Recent Progress in Cartilage Lubrication. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005513. [PMID: 33759245 DOI: 10.1002/adma.202005513] [Citation(s) in RCA: 127] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/23/2020] [Indexed: 05/18/2023]
Abstract
Healthy articular cartilage, covering the ends of bones in major joints such as hips and knees, presents the most efficiently-lubricated surface known in nature, with friction coefficients as low as 0.001 up to physiologically high pressures. Such low friction is indeed essential for its well-being. It minimizes wear-and-tear and hence the cartilage degradation associated with osteoarthritis, the most common joint disease, and, by reducing shear stress on the mechanotransductive, cartilage-embedded chondrocytes (the only cell type in the cartilage), it regulates their function to maintain homeostasis. Understanding the origins of such low friction of the articular cartilage, therefore, is of major importance in order to alleviate disease symptoms, and slow or even reverse its breakdown. This progress report considers the relation between frictional behavior and the cellular mechanical environment in the cartilage, then reviews the mechanism of lubrication in the joints, in particular focusing on boundary lubrication. Following recent advances based on hydration lubrication, a proposed synergy between different molecular components of the synovial joints, acting together in enabling the low friction, has been proposed. Additionally, recent development of natural and bio-inspired lubricants is reviewed.
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Affiliation(s)
- Weifeng Lin
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Jacob Klein
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 76100, Israel
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Rothammer B, Marian M, Rummel F, Schroeder S, Uhler M, Kretzer JP, Tremmel S, Wartzack S. Rheological behavior of an artificial synovial fluid - influence of temperature, shear rate and pressure. J Mech Behav Biomed Mater 2020; 115:104278. [PMID: 33340776 DOI: 10.1016/j.jmbbm.2020.104278] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 10/30/2020] [Accepted: 12/12/2020] [Indexed: 02/06/2023]
Abstract
Despite the excellent clinical performance of joint replacements, wear-induced aseptic loosening is a main cause of premature implant failure. Tribological testing is usually carried out using bovine serum as an artificial synovial fluid. In order to gain new insights into the suitability to simulate human synovial fluid and provide recommendations for the conditions of tribological testing, accurate rheological measurements on the influence of temperature, shear rate and pressure on density and viscosity were performed. Thus, a temperature dependence of density and viscosity could be verified, whereas both values decreased with higher temperatures. The temperature dependency of viscosity could be approximated by an Arrhenius model. Moreover, shear-thinning characteristics could be demonstrated and fitted to a Cross model, which agreed well with investigations on human synovial fluid reported in literature. Furthermore, an anomaly of pressure dependence of viscosity was found and correlated with the behavior of water as a main constituent. At room temperature, the viscosity initially decreased to a minimum and then increased again as a function of pressure. This was no longer distinct at human body temperatures. Consequently, the present study confirms the suitability of bovine serum as a substitute synovial fluid and emphasizes the importance of realistic testing conditions in order to ensure transferability and comparability.
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Affiliation(s)
- Benedict Rothammer
- Engineering Design, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Max Marian
- Engineering Design, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | | | - Stefan Schroeder
- Laboratory of Biomechanics and Implant Research, Heidelberg University Hospital, Heidelberg, Germany.
| | - Maximilian Uhler
- Laboratory of Biomechanics and Implant Research, Heidelberg University Hospital, Heidelberg, Germany.
| | - J Philippe Kretzer
- Laboratory of Biomechanics and Implant Research, Heidelberg University Hospital, Heidelberg, Germany.
| | - Stephan Tremmel
- Engineering Design and CAD, University of Bayreuth, Bayreuth, Germany.
| | - Sandro Wartzack
- Engineering Design, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
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Link JM, Salinas EY, Hu JC, Athanasiou KA. The tribology of cartilage: Mechanisms, experimental techniques, and relevance to translational tissue engineering. Clin Biomech (Bristol, Avon) 2020; 79:104880. [PMID: 31676140 PMCID: PMC7176516 DOI: 10.1016/j.clinbiomech.2019.10.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 10/03/2019] [Accepted: 10/17/2019] [Indexed: 02/07/2023]
Abstract
Diarthrodial joints, found at the ends of long bones, function to dissipate load and allow for effortless articulation. Essential to these functions are cartilages, soft hydrated tissues such as hyaline articular cartilage and the knee meniscus, as well as lubricating synovial fluid. Maintaining adequate lubrication protects cartilages from wear, but a decrease in this function leads to tissue degeneration and pathologies such as osteoarthritis. To study cartilage physiology, articular cartilage researchers have employed tribology, the study of lubrication and wear between two opposing surfaces, to characterize both native and engineered tissues. The biochemical components of synovial fluid allow it to function as an effective lubricant that exhibits shear-thinning behavior. Although tribological properties are recognized to be essential to native tissue function and a critical characteristic for translational tissue engineering, tribology is vastly understudied when compared to other mechanical properties such as compressive moduli. Further, tribometer configurations and testing modalities vary greatly across laboratories. This review aims to define commonly examined tribological characteristics and discuss the structure-function relationships of biochemical constituents known to contribute to tribological properties in native tissue, address the variations in experimental set-ups by suggesting a move toward standard testing practices, and describe how tissue-engineered cartilages may be augmented to improve their tribological properties.
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Affiliation(s)
- Jarrett M. Link
- 3131 Engineering Hall, Department of Biomedical Engineering, University of California, Irvine, California 92617, USA
| | - Evelia Y. Salinas
- 3131 Engineering Hall, Department of Biomedical Engineering, University of California, Irvine, California 92617, USA
| | - Jerry C. Hu
- 3131 Engineering Hall, Department of Biomedical Engineering, University of California, Irvine, California 92617, USA
| | - Kyriacos A. Athanasiou
- 3131 Engineering Hall, Department of Biomedical Engineering, University of California, Irvine, California 92617, USA
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The Role of Hyaluronic Acid in Cartilage Boundary Lubrication. Cells 2020; 9:cells9071606. [PMID: 32630823 PMCID: PMC7407873 DOI: 10.3390/cells9071606] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 06/27/2020] [Accepted: 06/30/2020] [Indexed: 01/23/2023] Open
Abstract
Hydration lubrication has emerged as a new paradigm for lubrication in aqueous and biological media, accounting especially for the extremely low friction (friction coefficients down to 0.001) of articular cartilage lubrication in joints. Among the ensemble of molecules acting in the joint, phosphatidylcholine (PC) lipids have been proposed as the key molecules forming, in a complex with other molecules including hyaluronic acid (HA), a robust layer on the outer surface of the cartilage. HA, ubiquitous in synovial joints, is not in itself a good boundary lubricant, but binds the PC lipids at the cartilage surface; these, in turn, massively reduce the friction via hydration lubrication at their exposed, highly hydrated phosphocholine headgroups. An important unresolved issue in this scenario is why the free HA molecules in the synovial fluid do not suppress the lubricity by adsorbing simultaneously to the opposing lipid layers, i.e., forming an adhesive, dissipative bridge between them, as they slide past each other during joint articulation. To address this question, we directly examined the friction between two hydrogenated soy PC (HSPC) lipid layers (in the form of liposomes) immersed in HA solution or two palmitoyl-oleoyl PC (POPC) lipid layers across HA-POPC solution using a surface force balance (SFB). The results show, clearly and surprisingly, that HA addition does not affect the outstanding lubrication provided by the PC lipid layers. A possible mechanism indicated by our data that may account for this is that multiple lipid layers form on each cartilage surface, so that the slip plane may move from the midplane between the opposing surfaces, which is bridged by the HA, to an HA-free interface within a multilayer, where hydration lubrication is freely active. Another possibility suggested by our model experiments is that lipids in synovial fluid may complex with HA, thereby inhibiting the HA molecules from adhering to the lipids on the cartilage surfaces.
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Rebenda D, Vrbka M, Čípek P, Toropitsyn E, Nečas D, Pravda M, Hartl M. On the Dependence of Rheology of Hyaluronic Acid Solutions and Frictional Behavior of Articular Cartilage. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E2659. [PMID: 32545213 PMCID: PMC7321645 DOI: 10.3390/ma13112659] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/03/2020] [Accepted: 06/09/2020] [Indexed: 01/27/2023]
Abstract
Hyaluronic acid (HA) injections represent one of the most common methods for the treatment of osteoarthritis. However, the clinical results of this method are unambiguous mainly because the mechanism of action has not been clearly clarified yet. Viscosupplementation consists, inter alia, of the improvement of synovial fluid rheological properties by injected solution. The present paper deals with the effect of HA molecular weight on the rheological properties of its solutions and also on friction in the articular cartilage model. Viscosity and viscoelastic properties of HA solutions were analyzed with a rotational rheometer in a cone-plate and plate-plate configuration. In total, four HA solutions with molecular weights between 77 kDa and 2010 kDa were tested. The frictional measurements were realized on a commercial tribometer Bruker UMT TriboLab, while the coefficient of friction (CoF) dependency on time was measured. The contact couple consisted of the articular cartilage pin and the plate made from optical glass. The contact was fully flooded with tested HA solutions. Results showed a strong dependency between HA molecular weight and its rheological properties. However, no clear dependence between HA molecular weight and CoF was revealed from the frictional measurements. This study presents new insight into the dependence between rheological and frictional behavior of the articular cartilage, while such an extensive investigation has not been presented before.
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Affiliation(s)
- David Rebenda
- Faculty of Mechanical Engineering, Brno University of Technology, 616 69 Brno, Czech Republic; (M.V.); (P.Č.); (D.N.); (M.H.)
| | - Martin Vrbka
- Faculty of Mechanical Engineering, Brno University of Technology, 616 69 Brno, Czech Republic; (M.V.); (P.Č.); (D.N.); (M.H.)
| | - Pavel Čípek
- Faculty of Mechanical Engineering, Brno University of Technology, 616 69 Brno, Czech Republic; (M.V.); (P.Č.); (D.N.); (M.H.)
| | - Evgeniy Toropitsyn
- Contipro a.s., Dolní Dobrouč 401, 561 02 Dolní Dobrouč, Czech Republic; (E.T.); (M.P.)
| | - David Nečas
- Faculty of Mechanical Engineering, Brno University of Technology, 616 69 Brno, Czech Republic; (M.V.); (P.Č.); (D.N.); (M.H.)
| | - Martin Pravda
- Contipro a.s., Dolní Dobrouč 401, 561 02 Dolní Dobrouč, Czech Republic; (E.T.); (M.P.)
| | - Martin Hartl
- Faculty of Mechanical Engineering, Brno University of Technology, 616 69 Brno, Czech Republic; (M.V.); (P.Č.); (D.N.); (M.H.)
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9
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Biotribology of Synovial Cartilage: A New Method for Visualization of Lubricating Film and Simultaneous Measurement of the Friction Coefficient. MATERIALS 2020; 13:ma13092075. [PMID: 32366009 PMCID: PMC7254223 DOI: 10.3390/ma13092075] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 04/23/2020] [Accepted: 04/27/2020] [Indexed: 11/23/2022]
Abstract
A healthy natural synovial joint is very important for painless active movement of the natural musculoskeletal system. The right functioning of natural synovial joints ensures well lubricated contact surfaces with a very low friction coefficient and wear of cartilage tissue. The present paper deals with a new method for visualization of lubricating film with simultaneous measurements of the friction coefficient. This can contribute to better understanding of lubricating film formation in a natural synovial joint. A newly developed device, a reciprocating tribometer, is used to allow for simultaneous measurement of friction forces with contact visualization by fluorescence microscopy. The software allowing for snaps processing and subsequent evaluation of fluorescence records is developed. The evaluation software and the follow-up evaluation procedure are also described. The experiments with cartilage samples and model synovial fluid are carried out, and the new software is applied to provide their evaluation. The primary results explaining a connection between lubrication and friction are presented. The results show a more significant impact of albumin proteins on the lubrication process, whereas its clusters create a more stable lubrication layer. A decreasing trend of protein cluster count, which corresponds to a decrease in the thickness of the lubrication film, is found in all experiments. The results highlight a deeper connection between the cartilage friction and the lubrication film formation, which allows for better understanding of the cartilage lubrication mechanism.
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10
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A method for the assessment of the coefficient of friction of articular cartilage and a replacement biomaterial. J Mech Behav Biomed Mater 2020; 103:103580. [DOI: 10.1016/j.jmbbm.2019.103580] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/27/2019] [Accepted: 12/02/2019] [Indexed: 11/17/2022]
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11
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Kajinami N, Matsumoto M. Polymer brush in articular cartilage lubrication: Nanoscale modelling and simulation. Biophys Physicobiol 2020; 16:466-472. [PMID: 31984198 PMCID: PMC6976006 DOI: 10.2142/biophysico.16.0_466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 09/17/2019] [Indexed: 12/01/2022] Open
Abstract
Human knee joints move smoothly under high load conditions due to articular cartilage and synovial fluid. Much attention is paid to the role of proteoglycans. It is suggested that a part of proteoglycan forms aggregate on the cartilage surface, making a polymer brush, which has an important role in lubrication. In order to examine the lubrication mechanism in detail, we constructed a full atom model of a polymer brush system, and carried out a series of molecular dynamics simulations to analyze its frictional properties under constant shear. We use chondroitin 6-sulfate molecules grafted on resilient surface as the polymer brush and water with sodium ions as the synovial liquid. In the steady state, polymers have large deformation and the flow of synovial fluid becomes deviate from the Coutette flow, leading to a drastic reduction of friction. Longer chains have larger reduction.
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Affiliation(s)
- Nobuhiko Kajinami
- Department of Mechanical Engineering and Science, Graduated School of Engineering, Kyoto University, Kyoto 615-8540, Japan
| | - Mitsuhiro Matsumoto
- Department of Mechanical Engineering and Science, Graduated School of Engineering, Kyoto University, Kyoto 615-8540, Japan
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Stotter C, Stojanović B, Bauer C, Rodríguez Ripoll M, Franek F, Klestil T, Nehrer S. Effects of Loading Conditions on Articular Cartilage in a Metal-on-Cartilage Pairing. J Orthop Res 2019; 37:2531-2539. [PMID: 31334864 PMCID: PMC6899800 DOI: 10.1002/jor.24426] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/15/2019] [Indexed: 02/04/2023]
Abstract
The aim of this in vitro study was to investigate the response of articular cartilage to frictional load when sliding against a metal implant, and identify potential mechanisms of damage to articular cartilage in a metal-on-cartilage pairing. Bovine osteochondral cylinders were reciprocally slid against metal cylinders (cobalt-chromium-molybdenum alloy) with several variations of load and sliding velocity using a microtribometer. The effects of different loads and velocities, and the resulting friction coefficients on articular cartilage, were evaluated by measuring histological and metabolic outcomes. Moreover, the biotribocorrosion of the metal was determined. Chondrocytes stimulated with high load and velocity showed increased metabolic activity and cartilage-specific gene expression. In addition, higher load and velocity resulted in biotribocorrosion of the metal implant and damage to the surface of the articular cartilage, whereas low velocity and a high coefficient of friction increased the expression of catabolic genes. Articular cartilage showed particular responses to load and velocity when sliding against a metal implant. Moreover, metal implants showed tribocorrosion. Therefore, corrosion particles may play a role in the mechano-biochemical wear of articular cartilage after implantation of a metal implant. These findings may be useful to surgeons performing resurfacing procedures and total knee arthroplasty. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society J Orthop Res 37:2531-2539, 2019.
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Affiliation(s)
- Christoph Stotter
- Faculty of Health and Medicine, Department for Health Sciences, Medicine and Research, Center for Regenerative MedicineDanube University KremsDr. Karl‐Dorrek‐Str. 30KremsA‐3500Austria,Department of Orthopedics and TraumatologyLK Baden‐Mödling‐HainburgWaltersdorfer Straße 75A‐2500BadenAustria
| | - Bojana Stojanović
- AC2T Research GmbHViktor Kaplan‐Straße 2A‐2700Wiener NeustadtAustria
| | - Christoph Bauer
- Faculty of Health and Medicine, Department for Health Sciences, Medicine and Research, Center for Regenerative MedicineDanube University KremsDr. Karl‐Dorrek‐Str. 30KremsA‐3500Austria
| | | | - Friedrich Franek
- AC2T Research GmbHViktor Kaplan‐Straße 2A‐2700Wiener NeustadtAustria
| | - Thomas Klestil
- Department of Orthopedics and TraumatologyLK Baden‐Mödling‐HainburgWaltersdorfer Straße 75A‐2500BadenAustria,Faculty of Health and Medicine, Department for Health Sciences, Medicine and ResearchDanube University KremsDr. Karl‐Dorrek‐Str. 30KremsA‐3500Austria
| | - Stefan Nehrer
- Faculty of Health and Medicine, Department for Health Sciences, Medicine and Research, Center for Regenerative MedicineDanube University KremsDr. Karl‐Dorrek‐Str. 30KremsA‐3500Austria
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13
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Prekasan D, Saju KK. Tribological effectiveness of viscosupplements for osteoarthritis in knee joint. SN APPLIED SCIENCES 2019. [DOI: 10.1007/s42452-019-1030-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Bonnevie ED, Galesso D, Secchieri C, Bonassar LJ. Frictional characterization of injectable hyaluronic acids is more predictive of clinical outcomes than traditional rheological or viscoelastic characterization. PLoS One 2019; 14:e0216702. [PMID: 31075142 PMCID: PMC6510437 DOI: 10.1371/journal.pone.0216702] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 04/28/2019] [Indexed: 02/06/2023] Open
Abstract
Hyaluronic acid injections have been a mainstay of arthritis treatment for decades. However, much controversy remains about their clinical efficacy and their potential mechanism of action. This approach to arthritis therapy is often called viscosupplementation, a term which is rooted in the elevated viscosity of the injected solutions. This terminology also suggests a mechanical pathway of action and further implies that their efficacy is dependent on viscosity. Notably, previous studies of the relationship between viscous properties of hyaluronic acid solutions and their clinical efficacy have not been definitive. Recently we developed an experimental and analytical framework for studying cartilage lubrication that captures the Stribeck-like behavior of cartilage in an elastoviscous transition curve. Here we apply this framework to study the lubricating behavior of six hyaluronan products currently used for injectable arthritis therapy in the US. Despite the fact that the source and chemical modifications endow these products with a range of lubricating properties, we show that the lubricating effect of all of these materials can be described by this Stribeck-like elastoviscous transition. Fitting this data to the elastoviscous transition model enables the calculation of effective lubricating viscosities for each material, which differ substantially from the viscosities measured using standard rheometry. Further we show that while data from standard rheometry are poor predictors of clinical performance of these materials, measurements of friction coefficient and effective lubricating viscosity correlate well (R2 = 0.77; p < 0.005) with assessments of improved clinical function reported previously. This approach offers both a novel method that can be used to evaluate potential clinical efficacy of hyaluronic acid formulations and provide new insight on their mode of action.
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Affiliation(s)
- Edward D. Bonnevie
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, United States of America
| | | | | | - Lawrence J. Bonassar
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, United States of America
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States of America
- * E-mail:
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15
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Sakai N, Yarimitsu S, Sawae Y, Komori M, Murakami T. Biomimetic artificial cartilage: fibre‐reinforcement of PVA hydrogel to promote biphasic lubrication mechanism. BIOSURFACE AND BIOTRIBOLOGY 2019. [DOI: 10.1049/bsbt.2018.0031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Nobuo Sakai
- Integrated Systems EngineeringKyushu Institute of TechnologyKitakyushuJapan
| | - Seido Yarimitsu
- Intelligent Mechanical Systems, System DesignTokyo Metropolitan UniversityTokyoJapan
| | - Yoshinori Sawae
- Mechanical EngineeringKyushu UniversityFukuokaJapan
- Research Center for Advanced BiomechanicsKyushu UniversityFukuokaJapan
| | - Mochimitsu Komori
- Integrated Systems EngineeringKyushu Institute of TechnologyKitakyushuJapan
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Weller WJ. Emerging Technologies in Upper Extremity Surgery: Polyvinyl Alcohol Hydrogel Implant for Thumb Carpometacarpal Arthroplasty and Processed Nerve Allograft and Nerve Conduit for Digital Nerve Repairs. Orthop Clin North Am 2019; 50:87-93. [PMID: 30477709 DOI: 10.1016/j.ocl.2018.08.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In the field of upper extremity surgery there are myriad new and developing technologies. The purpose of this article is to highlight a few of the most compelling new technologies and review their background, indications for use, and most recently reported outcomes in clinical practice.
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Affiliation(s)
- William J Weller
- Department of Orthopaedic Surgery and Biomedical Engineering, University of Tennessee-Campbell Clinic, 1211 Union Avenue, Suite 510, Memphis, TN 38104, USA.
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17
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Yamaguchi T, Sato R, Sawae Y. Propagation of Fatigue Cracks in Friction of Brittle Hydrogels. Gels 2018; 4:E53. [PMID: 30674829 PMCID: PMC6209280 DOI: 10.3390/gels4020053] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 06/05/2018] [Accepted: 06/06/2018] [Indexed: 11/16/2022] Open
Abstract
In order to understand fatigue crack propagation behavior in the friction of brittle hydrogels, we conducted reciprocating friction experiments between a hemi-cylindrical indenter and an agarose hydrogel block. We found that the fatigue life is greatly affected by the applied normal load as well as adhesion strength at the bottom of the gel⁻substrate interface. On the basis of in situ visualizations of the contact areas and observations of the fracture surfaces after the friction experiments, we suggest that the mechanical condition altered by the delamination of the hydrogel from the bottom substrate plays an essential role in determining the fatigue life of the hydrogel.
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Affiliation(s)
- Tetsuo Yamaguchi
- Department of Mechanical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
- International Institute for Carbon-Neutral Energy Research, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
| | - Ryuichiro Sato
- Department of Mechanical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
| | - Yoshinori Sawae
- Department of Mechanical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
- International Institute for Carbon-Neutral Energy Research, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
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Sakai N, Yarimitsu S, Sawae Y, Komori M, Murakami T. Transitional behaviour between biphasic lubrication and soft elastohydrodynamic lubrication of poly(vinyl alcohol) hydrogel using microelectromechanical system pressure sensor. BIOSURFACE AND BIOTRIBOLOGY 2018. [DOI: 10.1049/bsbt.2018.0001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Nobuo Sakai
- Integrated System EngineeringKyushu Institute of TechnologyKitakyushuJapan
| | - Seido Yarimitsu
- Intelligent Mechanical SystemsSystem DesignTokyo Metropolitan UniversityTokyoJapan
| | - Yoshinori Sawae
- Mechanical EngineeringKyushu UniversityFukuokaJapan
- Research Center for Advanced BiomechanicsKyushu UniversityFukuokaJapan
| | - Mochimitsu Komori
- Integrated System EngineeringKyushu Institute of TechnologyKitakyushuJapan
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Abstract
The major synovial joints such as hips and knees are uniquely efficient tribological systems, able to articulate over a wide range of shear rates with a friction coefficient between the sliding cartilage surfaces as low as 0.001 up to pressures of more than 100 atm. No human-made material can match this. The means by which such surfaces maintain their very low friction has been intensively studied for decades and has been attributed to fluid-film and boundary lubrication. Here, we focus especially on the latter: the reduction of friction by molecular layers at the sliding cartilage surfaces. In particular, we discuss such lubrication in the light of very recent advances in our understanding of boundary effects in aqueous media based on the paradigms of hydration lubrication and of the synergism between different molecular components of the synovial joints (namely hyaluronan, lubricin, and phospholipids) in enabling this lubrication.
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Affiliation(s)
- Sabrina Jahn
- Weizmann Institute of Science, Rehovot 76100, Israel;
| | - Jasmine Seror
- Weizmann Institute of Science, Rehovot 76100, Israel;
| | - Jacob Klein
- Weizmann Institute of Science, Rehovot 76100, Israel;
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20
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Ultra-low friction between boundary layers of hyaluronan-phosphatidylcholine complexes. Acta Biomater 2017; 59:283-292. [PMID: 28669720 DOI: 10.1016/j.actbio.2017.06.043] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 11/21/2022]
Abstract
The boundary layers coating articular cartilage in synovial joints constitute unique biomaterials, providing lubricity at levels unmatched by any human-made materials. The underlying molecular mechanism of this lubricity, essential to joint function, is not well understood. Here we study the interactions between surfaces bearing attached hyaluronan (hyaluronic acid, or HA) to which different phosphatidylcholine (PC) lipids had been added, in the form of small unilamellar vesicles (SUVs or liposomes), using a surface force balance, to shed light on possible cartilage boundary lubrication by such complexes. Surface-attached HA was complexed with different PC lipids (hydrogenated soy PC (HSPC), 1,2-dimyristoyl-sn-glycero-3-PC (DMPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-PC (POPC)), followed by rinsing. Atomic force microscopy (AFM) and cryo-scanning electron microscopy (Cryo-SEM) were used to image the HA-PC surface complexes following addition of the SUVs. HA-HSPC complexes provide very efficient lubrication, with friction coefficients as low as μ∼0.001 at physiological pressures P≈150atm, while HA-DMPC and HA-POPC complexes are efficient only at low P (up to 10-20atm). The friction reduction in all cases is attributed to hydration lubrication by highly-hydrated phosphocholine groups exposed by the PC-HA complexes. The greater robustness at high P of the HSPC (C16(15%),C18(85%)) complexes relative to the DMPC ((C14)2) or POPC (C16, C18:1) complexes is attributed to the stronger van der Waals attraction between the HSPC acyl tails, relative to the shorter or un-saturated tails of the other two lipids. Our results shed light on possible lubrication mechanisms at the articular cartilage surface in joints. STATEMENT OF SIGNIFICANCE Can designed biomaterials emulate the unique lubrication ability of articular cartilage, and thus provide potential alleviation to friction-related joint diseases? This is the motivation behind the present study. The principles of cartilage lubrication have attracted considerable attention for decades, and several models have been proposed to elucidate it, however, the mechanism of this ultralow friction is still not clear. In this paper we explore the recent suggestion that its efficient lubrication arises from boundary layers of hyaluronan-lipid complexes at its surface, in particular exploring a range of different phosphatidylcholines (PCs) mimicking the wide range of PCs in synovial joints. The present study suggests a synergistic lubricating behavior of the different lipids in living joints, and potential treatment directions using such biomaterial complexes for widespread cartilage-friction-related diseases such as osteoarthritis.
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Zander T, Wieland DF, Raj A, Wang M, Nowak B, Krywka C, Dėdinaitė A, Claesson PM, Garamus VM, Schreyer A, Willumeit-Römer R. The influence of hyaluronan on the structure of a DPPC—bilayer under high pressures. Colloids Surf B Biointerfaces 2016; 142:230-238. [DOI: 10.1016/j.colsurfb.2016.02.040] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 02/02/2016] [Accepted: 02/03/2016] [Indexed: 02/05/2023]
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22
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Sakai N, Hashimoto C, Yarimitsu S, Sawae Y, Komori M, Murakami T. A functional effect of the superficial mechanical properties of articular cartilage as a load bearing system in a sliding condition. BIOSURFACE AND BIOTRIBOLOGY 2016. [DOI: 10.1016/j.bsbt.2016.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Mechanical properties derived from phase separation in co-polymer hydrogels. J Mech Behav Biomed Mater 2016; 55:286-294. [DOI: 10.1016/j.jmbbm.2015.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/05/2015] [Accepted: 11/09/2015] [Indexed: 11/19/2022]
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Shi Y, Xiong D, Li J, Wang N. The water-locking and cross-linking effects of graphene oxide on the load-bearing capacity of poly(vinyl alcohol) hydrogel. RSC Adv 2016. [DOI: 10.1039/c6ra21272g] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The GO sheets bound part of water molecules due to the abundant oxygen-containing functional groups on its surface and impede the water infiltration between the PVA molecules, improving the water-locking ability of the PVA/GO composites.
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Affiliation(s)
- Yan Shi
- School of Materials Science and Engineering
- Nanjing University of Science and Technology
- Nanjing 210094
- P. R. China
| | - Dangsheng Xiong
- School of Materials Science and Engineering
- Nanjing University of Science and Technology
- Nanjing 210094
- P. R. China
- Jiangsu Key Laboratory of Advanced Micro/Nano Materials and Technology
| | - Jianliang Li
- School of Materials Science and Engineering
- Nanjing University of Science and Technology
- Nanjing 210094
- P. R. China
| | - Nan Wang
- Jiangsu Key Laboratory of Advanced Micro/Nano Materials and Technology
- Nanjing 210094
- P. R. China
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Murakami T, Yarimitsu S, Nakashima K, Sakai N, Yamaguchi T, Sawae Y, Suzuki A. Biphasic and boundary lubrication mechanisms in artificial hydrogel cartilage: A review. Proc Inst Mech Eng H 2015; 229:864-78. [DOI: 10.1177/0954411915611160] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Various studies on the application of artificial hydrogel cartilage to cartilage substitutes and artificial joints have been conducted. It is expected in clinical application of artificial hydrogel cartilage that not only soft-elastohydrodynamic lubrication but biphasic, hydration, gel-film and boundary lubrication mechanisms will be effective to sustain extremely low friction and minimal wear in daily activities similar to healthy natural synovial joints with adaptive multimode lubrication. In this review article, the effectiveness of biphasic lubrication and boundary lubrication in hydrogels in thin film condition is focused in relation to the structures and properties of hydrogels. As examples, the tribological behaviors in three kinds of poly(vinyl alcohol) hydrogels with high water content are compared, and the importance of lubrication mechanism in biomimetic artificial hydrogel cartilage is discussed to extend the durability of cartilage substitute.
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Affiliation(s)
- Teruo Murakami
- Research Center for Advanced Biomechanics, Kyushu University, Fukuoka, Japan
| | - Seido Yarimitsu
- Research Center for Advanced Biomechanics, Kyushu University, Fukuoka, Japan
- Faculty of System Design, Tokyo Metropolitan University, Tokyo, Japan
| | - Kazuhiro Nakashima
- Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka, Japan
| | - Nobuo Sakai
- Department of Applied Science for Integrated System Engineering, Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu, Japan
| | - Tetsuo Yamaguchi
- Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka, Japan
| | - Yoshinori Sawae
- Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka, Japan
| | - Atsushi Suzuki
- Department of Materials Science and Research Institute of Environment and Information Sciences, Yokohama National University, Yokohama, Japan
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Suzuki A, Sasaki S. Swelling and mechanical properties of physically crosslinked poly(vinyl alcohol) hydrogels. Proc Inst Mech Eng H 2015; 229:828-44. [DOI: 10.1177/0954411915615469] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Physically crosslinked poly(vinyl alcohol) gels are versatile biomaterials due to their excellent biocompatibility. In the past decades, physically crosslinked poly(vinyl alcohol) and poly(vinyl alcohol)-based hydrogels have been extensively studied for biomedical applications. However, these materials have not yet been implemented due to their mechanical strength. Physically crosslinked poly(vinyl alcohol) gels consist of a swollen amorphous network of poly(vinyl alcohol) physically crosslinked by microcrystallites. Although the mechanical properties can be improved to some extent by controlling the distribution of microcrystallites on the nano- and micro-scales, enhancing the mechanical properties while maintaining high water content remains very difficult. It may be technologically impossible to significantly improve the mechanical properties while keeping the gel’s high water absorbance ability using conventional fabrication methods. Physical and chemical understandings of the swelling and mechanical properties of physically crosslinked poly(vinyl alcohol) gels are considered here; some promising strategies for their practical applications are presented. This review focuses more on the recent studies on swelling and mechanical properties of poly(vinyl alcohol) hydrogels, prepared using only poly(vinyl alcohol) and pure water with no other chemicals, as potential biomedical materials.
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Affiliation(s)
- Atsushi Suzuki
- Department of Materials Science, Research Institute of Environment and Information Sciences, Yokohama National University, Yokohama, Japan
| | - Saori Sasaki
- Department of Materials Science, Research Institute of Environment and Information Sciences, Yokohama National University, Yokohama, Japan
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27
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Ide M, Matsumoto M. Tribology of polymer brush: microscale modelling and simulation. MOLECULAR SIMULATION 2015. [DOI: 10.1080/08927022.2014.913790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Role of hyaluronic acid and phospholipid in the lubrication of a cobalt-chromium head for total hip arthroplasty. Biointerphases 2015; 9:031007. [PMID: 25280848 DOI: 10.1116/1.4886255] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The tribological performance of total hip arthroplasty has an important influence on its success rate. This study examined the concentration-dependent role of hyaluronic acid (HA) and phospholipid (dipalmitoylphosphatidylcholine, DPPC) in the boundary lubricating ability of retrieved cobalt-chromium femoral heads. The microscale frictional coefficients (μ) were measured by atomic force microscopy using a rectangular silicon cantilever integrated with sharp silicon tips. In the case of HA lubricant, the frictional coefficients decreased significantly at concentrations of 2.0 (0.16 ± 0.03) and 3.5 mg/ml (0.11 ± 0.01) while increased at 5.0 mg/ml (0.15 ± 0.01), compared to that with phosphate buffer saline (0.25 ± 0.03). The concentration-dependent lubrication behavior of DPPC was most effective when DPPC was in the physiological concentration range, showing μ = 0.16 ± 0.01 in polypropylene glycol, and 0.05 ± 0.01, 0.02 ± 0.01, and 0.03 ± 0.01 at a DPPC concentration of 0.05, 0.2, and 3.0 mg/ml, respectively. Results obtained show significant differences between the DPPC concentration groups. Conclusively, the microscale frictional response of the retrieved CoCr femoral head has a significant dependence on the concentrations of HA and DPPC. Moreover, observed optimal concentration of HA and DPPC for effective lubrication is similar to that observed in normal human synovial fluid. Therefore, a retrieval of the synovia may be considered during total hip replacement surgeries in an effort for reduction of friction between head and liner of total hip replacement implants.
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SAKAI N, HAGIHARA Y, HASHIMOTO C, KOMORI M, SAWAE Y, MURAKAMI T. An estimation of mechanical propertes of articular cartilage for biphasic finite element analyses. ACTA ACUST UNITED AC 2015. [DOI: 10.1299/jbse.15-00228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Nobuo SAKAI
- Graduate School of Engineering, Kyushu Institute of Technology
| | | | - Chie HASHIMOTO
- Graduate School of Engineering, Kyushu Institute of Technology
| | | | | | - Teruo MURAKAMI
- Research Center for Advanced Biomechanics, Kyushu University
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Lee H, Kirkland WG, Whitmore RN, Theis KM, Young HE, Richardson AJ, Jackson RL, Hanson RR. Comparison of equine articular cartilage thickness in various joints. Connect Tissue Res 2014; 55:339-47. [PMID: 25111191 DOI: 10.3109/03008207.2014.949698] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE Thicknesses of fresh equine articular cartilage surfaces from the fetlock, carpal and stifle joints were measured employing a needle probe test. MATERIALS AND METHODS Eighty-seven samples used in measurement were cultivated from fetlock, carpal and stifle joints of 12 deceased within 4 h of death. After approximately three minutes of exposure to air during dissection, all cartilage samples were preserved in a saline solution to keep the articular cartilage hydrated for testing. The thickness was measured on five different spots on the same sample. The thicknesses of the fetlock, carpus and stifle were compared. RESULTS The articular cartilage of the stifle was thicker than the fetlock and carpus, while the fetlock and the carpus had similar thickness values. The average thickness of the fetlock, carpal and stifle joint are 0.86, 0.87 and 2.1 mm, respectively. They were statistically compared using the Student t-test. The differences on the articular cartilage thicknesses between the fetlock and stifle, and carpus and stifle were "very highly significant" (p < 0.001). This indicates that the articular cartilage thickness of the stifle is significantly different from that of the fetlock and carpus. Four different surfaces in the fetlock and four in the carpal joint were also compared. Significant differences between each set of the four surfaces were not observed. In the carpus, the difference in thickness between the distal radius and proximal third carpal bone articular cartilage surfaces as well as the proximal radial carpal bone and distal radial carpal bone articular cartilage surfaces were statistically significant.
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Affiliation(s)
- Hyeon Lee
- Department of Mechanical Engineering, Auburn University , Auburn, AL , USA and
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32
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Experimental Investigations of Biological Lubrication at the Nanoscale: The Cases of Synovial Joints and the Oral Cavity. LUBRICANTS 2013. [DOI: 10.3390/lubricants1040102] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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33
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Mohammadi H, Mequanint K, Herzog W. Computational aspects in mechanical modeling of the articular cartilage tissue. Proc Inst Mech Eng H 2013; 227:402-20. [DOI: 10.1177/0954411912470239] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This review focuses on the modeling of articular cartilage (at the tissue level), chondrocyte mechanobiology (at the cell level) and a combination of both in a multiscale computation scheme. The primary objective is to evaluate the advantages and disadvantages of conventional models implemented to study the mechanics of the articular cartilage tissue and chondrocytes. From monophasic material models as the simplest form to more complicated multiscale theories, these approaches have been frequently used to model articular cartilage and have contributed significantly to modeling joint mechanics, addressing and resolving numerous issues regarding cartilage mechanics and function. It should be noted that attentiveness is important when using different modeling approaches, as the choice of the model limits the applications available. In this review, we discuss the conventional models applicable to some of the mechanical aspects of articular cartilage such as lubrication, swelling pressure and chondrocyte mechanics and address some of the issues associated with the current modeling approaches. We then suggest future pathways for a more realistic modeling strategy as applied for the simulation of the mechanics of the cartilage tissue using multiscale and parallelized finite element method.
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Affiliation(s)
- Hadi Mohammadi
- School of Engineering, Faculty of Applied Science, The University of British Columbia, Okanagan Campus, Kelowna, British Columbia, Canada
| | - Kibret Mequanint
- Department of Chemical and Biochemical Engineering, the University of Western Ontario, London, Ontario, Canada
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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Blum MM, Ovaert TC. A novel polyvinyl alcohol hydrogel functionalized with organic boundary lubricant for use as low-friction cartilage substitute: Synthesis, physical/chemical, mechanical, and friction characterization. J Biomed Mater Res B Appl Biomater 2012; 100:1755-63. [DOI: 10.1002/jbm.b.32742] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 03/26/2012] [Accepted: 05/08/2012] [Indexed: 11/11/2022]
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Finite element analysis of the ovine hip: development, results and comparison with the human hip. Vet Comp Orthop Traumatol 2012; 25:301-6. [PMID: 22534728 DOI: 10.3415/vcot-11-09-0132] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 03/27/2012] [Indexed: 11/17/2022]
Abstract
OBJECTIVES The ovine hip is often used as an experimental research model to simulate the human hip. However, little is known about the contact pressures on the femoral and acetabular cartilage in the ovine hip, and if those are representative for the human hip. METHODS A model of the ovine hip, including the pelvis, femur, acetabular cartilage, femoral cartilage and ligamentum transversum, was built using computed tomography and micro-computed tomography. Using the finite element method, the peak forces were analysed during simulated walking. RESULTS The evaluation revealed that the contact pressure distribution on the femoral cartilage is horseshoe-shaped and reaches a maximum value of approximately 6 MPa. The maximum contact pressure is located on the dorsal acetabular side and is predominantly aligned in the cranial-to-caudal direction. The surface stresses acting on the pelvic bone reach an average value of approximately 2 MPa. CONCLUSIONS The contact pressure distribution, magnitude, and the mean surface stress in the ovine hip are similar to those described in the current literature for the human hip. This suggests that in terms of load distribution, the ovine hip is well suited for the preclinical testing of medical devices designed for the human hip.
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SAKAI N, HOSODA N, HAGIHARA Y, SAWAE Y, MURAKAMI T. ANALYSES OF FUNCTIONAL MECHANISM OF ARTICULAR CARTILAGE. ACTA ACUST UNITED AC 2012. [DOI: 10.3951/biomechanisms.21.251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Gleghorn JP, Doty SB, Warren RF, Wright TM, Maher SA, Bonassar LJ. Analysis of frictional behavior and changes in morphology resulting from cartilage articulation with porous polyurethane foams. J Orthop Res 2010; 28:1292-9. [PMID: 20309861 DOI: 10.1002/jor.21136] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Porous polyurethane foams (PUR) have been extensively evaluated as meniscal replacement materials and show great promise enabling infiltration of cells and fibrocartilage formation in vivo. Similar to most materials, PUR demonstrates progressive degeneration of opposing cartilage; however, the damage mechanism is impossible to determine because no information exists on the frictional properties of PUR-cartilage interfaces. The goals of this study were to characterize the frictional behavior of a cartilage-PUR interface across a range of articulating conditions and assess the resulting morphological changes to the cartilage surface following articulation. Articular cartilage was oscillated against PUR or stainless steel using phosphate-buffered saline (PBS) and synovial fluid as lubricants. Following friction testing, cartilage and PUR samples were analyzed with environmental scanning electron microscopy and histological staining to determine changes in tissue morphology. Stribeck-surface analysis demonstrated distinct lubrication modes; however, boundary mode lubrication was dominant in cartilage-PUR interfaces and the low-friction pressure-borne lubrication mechanism present in native joints was absent. Microscopy noted obvious wear, with disruption of the collagen architecture and concomitant proteoglycan loss in cartilage articulated against PUR. These data collectively point to the importance of frictional properties as design parameters for implants and materials for soft tissue replacement.
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Affiliation(s)
- Jason P Gleghorn
- Department of Biomedical Engineering, Cornell University, 149 Weill Hall, Ithaca, New York 14853, USA
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Bruck AL, Kanaga Karuppiah KS, Sundararajan S, Wang J, Lin Z. Friction and wear behavior of ultrahigh molecular weight polyethylene as a function of crystallinity in the presence of the phospholipid dipalmitoyl phosphatidylcholine. J Biomed Mater Res B Appl Biomater 2010; 93:351-8. [DOI: 10.1002/jbm.b.31587] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Anisotropic dynamic changes in the pore network structure, fluid diffusion and fluid flow in articular cartilage under compression. Biomaterials 2010; 31:3117-28. [PMID: 20144846 DOI: 10.1016/j.biomaterials.2010.01.102] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 01/15/2010] [Indexed: 10/19/2022]
Abstract
A compression cell designed to fit inside an NMR spectrometer was used to investigate the in situ mechanical strain response, structural changes to the internal pore structure, and the diffusion and flow of interstitial water in full-thickness cartilage samples as it was deforming dynamically under a constant compressive load (pressure). We distinguish between the hydrostatic pressure acting on the interstitial fluid and the pore pressure acting on the cartilage fibril network. Our results show that properties related to the pore matrix microstructure such as diffusion and hydraulic conductivity are strongly influenced by the hydrostatic pressure in the interstitial fluid of the dynamically deforming cartilage which differ significantly from the properties measured under static i.e. equilibrium loading conditions (when the hydrostatic pressure has relaxed back to zero). The magnitude of the hydrostatic fluid pressure also appears to affect the way cartilage's pore matrix changes during deformation with implications for the diffusion and flow-driven fluid transport through the deforming pore matrix. We also show strong evidence for a highly anisotropic pore structure and deformational dynamics that allows cartilage to deform without significantly altering the axial porosity of the matrix even at very large strains. The insensitivity of the axial porosity to compressive strain may be playing a critical function in directing the flow of pressurized interstitial fluid in the compressed cartilage to the surface, to support the load, and provide a protective interfacial fluid film that 'weeps' out from the deforming tissue and thereby enhances the (elasto)hydrodynamic efficacy of sliding joints. Our results appear to show a close synergy between the structure of cartilage and both the hydrodynamic and boundary lubrication mechanisms.
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An equine joint friction test model using a cartilage-on-cartilage arrangement. Vet J 2010; 183:148-52. [DOI: 10.1016/j.tvjl.2008.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Revised: 11/10/2008] [Accepted: 12/05/2008] [Indexed: 11/23/2022]
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DuRaine G, Neu CP, Chan SMT, Komvopoulos K, June RK, Reddi AH. Regulation of the friction coefficient of articular cartilage by TGF-beta1 and IL-1beta. J Orthop Res 2009; 27:249-56. [PMID: 18683879 DOI: 10.1002/jor.20713] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Articular cartilage functions to provide a low-friction surface for joint movement for many decades of life. Superficial zone protein (SZP) is a glycoprotein secreted by chondrocytes in the superficial layer of articular cartilage that contributes to effective boundary lubrication. In both cell and explant cultures, TGF-beta1 and IL-1beta have been demonstrated to, respectively, upregulate and downregulate SZP protein levels. It was hypothesized that the friction coefficient of articular cartilage could also be modulated by these cytokines through SZP regulation. The friction coefficient between cartilage explants (both untreated and treated with TGF-beta1 or IL-1beta) and a smooth glass surface due to sliding in the boundary lubrication regime was measured with a pin-on-disk tribometer. SZP was quantified using an enzyme-linked immunosorbant assay and localized by immunohistochemistry. Both TGF-beta1 and IL-1beta treatments resulted in the decrease of the friction coefficient of articular cartilage in a location- and time-dependent manner. Changes in the friction coefficient due to the TGF-beta1 treatment corresponded to increased depth of SZP staining within the superficial zone, while friction coefficient changes due to the IL-1beta treatment were independent of SZP depth of staining. However, the changes induced by the IL-1beta treatment corresponded to changes in surface roughness, determined from the analysis of surface images obtained with an atomic force microscope. These findings demonstrate that the low friction of articular cartilage can be modified by TGF-beta1 and IL-1beta treatment and that the friction coefficient depends on multiple factors, including SZP localization and surface roughness.
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Affiliation(s)
- Grayson DuRaine
- Center for Tissue Regeneration and Repair, Department of Orthopaedic Surgery, University of California, Davis, Medical Center, Sacramento, CA 95817, USA
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Katta J, Jin Z, Ingham E, Fisher J. Biotribology of articular cartilage--a review of the recent advances. Med Eng Phys 2008; 30:1349-63. [PMID: 18993107 DOI: 10.1016/j.medengphy.2008.09.004] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 09/17/2008] [Accepted: 09/22/2008] [Indexed: 11/24/2022]
Abstract
A brief review of the advances in the biotribology of articular cartilage in the last decade or so are presented. The review is limited to experimental friction and wear studies involving articular cartilage. The importance of developing in vitro models as tools not only to understand the cartilage tribological characteristics, but to evaluate current and future cartilage substitution and treatment therapies is discussed.
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Affiliation(s)
- Jayanth Katta
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK
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Shepherd DET, Azangwe G. Synthetic versus tissue-engineered implants for joint replacement. Appl Bionics Biomech 2008. [DOI: 10.1080/11762320701816966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Schmidt TA, Sah RL. Effect of synovial fluid on boundary lubrication of articular cartilage. Osteoarthritis Cartilage 2007; 15:35-47. [PMID: 16859933 DOI: 10.1016/j.joca.2006.06.005] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Accepted: 06/05/2006] [Indexed: 02/02/2023]
Abstract
OBJECTIVES The lubrication of articulating cartilage surfaces in joints occurs through several distinct modes. In the boundary mode of lubrication, load is supported by surface-to-surface contact, a feature that makes this mode particularly important for maintenance of the normally pristine articular surface. A boundary mode of lubrication is indicated by a kinetic friction coefficient being invariant with factors that influence formation of a fluid film, including sliding velocity and axial load. The objectives of this study were to (1) implement and extend an in vitro articular cartilage-on-cartilage lubrication test to elucidate the dependence of the friction properties on sliding velocity, axial load, and time, and establish conditions where a boundary mode of lubrication is dominant, and (2) determine the effects of synovial fluid (SF) on boundary lubrication using this test. METHODS Fresh bovine osteochondral samples were analyzed in an annulus-on-disk rotational configuration, maintaining apposed articular surfaces in contact, to determine static (mu(static) and mu(static),(N(eq)) and kinetic ([mu(kinetic)] and [mu(kinetic),(N(eq))]) friction coefficients, each normalized to the instantaneous and equilibrium (N(eq)) normal loads, respectively. RESULTS With increasing pre-sliding durations, mu(static) and mu(static),(N(eq)) were similar, and increased up to 0.43 +/- 0.03 in phosphate buffered saline (PBS) and 0.19 +/- 0.01 in SF, whereas [mu(kinetic)] and [mu(kinetic),(N(eq))] were steady. Over a range of sliding velocities of 0.1-1 mm/s and compression levels of 18% and 24%, [mu(kinetic)] was 0.072 +/- 0.010 in PBS and 0.014 +/- 0.003 in SF, and [mu(kinetic),(N(eq))] was 0.093 +/- 0.005 in PBS and 0.018 +/- 0.002 in SF. CONCLUSIONS A boundary mode of lubrication was achieved in a cartilage-on-cartilage test configuration. SF functioned as an effective friction-lowering boundary lubricant for native articular cartilage surfaces.
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Affiliation(s)
- T A Schmidt
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California--San Diego, La Jolla, CA 92093, USA
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Schmidt TA, Gastelum NS, Nguyen QT, Schumacher BL, Sah RL. Boundary lubrication of articular cartilage: Role of synovial fluid constituents. ACTA ACUST UNITED AC 2007; 56:882-91. [PMID: 17328061 DOI: 10.1002/art.22446] [Citation(s) in RCA: 343] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE To determine whether the synovial fluid (SF) constituents hyaluronan (HA), proteoglycan 4 (PRG4), and surface-active phospholipids (SAPL) contribute to boundary lubrication, either independently or additively, at an articular cartilage-cartilage interface. METHODS Cartilage boundary lubrication tests were performed with fresh bovine osteochondral samples. Tests were performed using graded concentrations of SF, HA, and PRG4 alone, a physiologic concentration of SAPL, and various combinations of HA, PRG4, and SAPL at physiologic concentrations. Static (mu(static, Neq)) and kinetic (<mu(kinetic, Neq)>) friction coefficients were calculated. RESULTS Normal SF functioned as an effective boundary lubricant both at a concentration of 100% (<mu(kinetic, Neq)> = 0.025) and at a 3-fold dilution (<mu(kinetic, Neq)> = 0.029). Both HA and PRG4 contributed independently to a low mu in a dose-dependent manner. Values of <mu(kinetic, Neq)> decreased from approximately 0.24 in phosphate buffered saline to 0.12 in 3,300 mug/ml HA and 0.11 in 450 mug/ml PRG4. HA and PRG4 in combination lowered mu further at the high concentrations, attaining a <mu(kinetic, Neq)> value of 0.066. SAPL at 200 mug/ml did not significantly lower mu, either independently or in combination with HA and PRG4. CONCLUSION The results described here indicate that SF constituents contribute, individually and in combination, both at physiologic and pathophysiologic concentrations, to the boundary lubrication of apposing articular cartilage surfaces. These results provide insight into the nature of the boundary lubrication of articular cartilage by SF and its constituents. They therefore provide insight regarding both the homeostatic maintenance of healthy joints and pathogenic processes in arthritic disease.
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Sabaratnam S, Coleman PJ, Mason RM, Levick JR. Interstitial matrix proteins determine hyaluronan reflection and fluid retention in rabbit joints: effect of protease. J Physiol 2006; 578:291-9. [PMID: 17008373 PMCID: PMC2075123 DOI: 10.1113/jphysiol.2006.119446] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Hyaluronan (HA) retention inside the synovial cavity of joints serves diverse protective roles. We tested the hypothesis that HA retention is mediated by the network of extracellular matrix proteins in the synovial lining. Cannulated rabbit knee joints were infused with HA solution with or without pretreatment by chymopapain, a collagen-sparing protease. Trans-synovial fluid escape rate was measured and, after a period of trans-synovial filtration, samples of intra-articular fluid and subsynovial fluid were analysed for HA to assess its trans-synovial ultrafiltration. In control joints, HA ultrafiltration was confirmed by postfiltration increases in intra-articular HA concentration (259 +/- 17% of infused concentration) and reduced subsynovial concentration (30 +/- 8%; n = 11). The proportion of HA molecules reflected by the synovium was 57-75%. Chymopapain treatment increased the hydraulic permeability of the synovial lining approximately 13-fold, almost abolished the trans-synovial difference in HA concentration and reduced the HA reflected fraction to 3-7% (n = 6; P < 0.001, ANOVA). Structural studies confirmed that chymopapain treatment depleted the matrix of proteoglycans but preserved its collagen. The findings thus demonstrate that HA ultrafiltration and synovial hydraulic permeability are determined by the network of non-collagen, extracellular matrix proteins. This may be important clinically, since protease activity is raised in rheumatoid arthritis, as are HA and fluid escape.
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Affiliation(s)
- S Sabaratnam
- Physiology, Basic Medical Sciences, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK
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Graindorge S, Ferrandez W, Ingham E, Jin Z, Twigg P, Fisher J. The role of the surface amorphous layer of articular cartilage in joint lubrication. Proc Inst Mech Eng H 2006; 220:597-607. [PMID: 16898217 DOI: 10.1243/09544119jeim122] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Articular cartilage is a complex soft tissue that performs multiple functions in the joint. In particular, the amorphous layer that covers the surface of articular cartilage is thought to play some role in lubrication. This study aimed to characterize the surface amorphous layer (SAL) using a variety of techniques, including environmental scanning electron microscopy, transmission electron microscopy, white light interferometry, and biochemical analysis of its composition. Friction tests were conducted to investigate the role of the SAL in lubrication. A protocol to remove successfully the SAL without damaging the underlying cartilage was developed and the material removed from healthy cartilage was found to contain approximately equal quantities of glycosaminoglycan (GAG), protein, and lipid. Cartilage-on-cartilage friction tests were conducted on fresh, healthy cartilage with and without the SAL, under both dynamic and static operating conditions. Removal of the SAL was not found to change the friction coefficient. However, subsequent staining of specimens indicated that the SAL had replenished during the test following loading. The replenished SAL was characterized and found to contain lipids and sulphated GAGs with undetectable protein. This study revealed experimental evidence of surface layer replenishment in articular cartilage. It was postulated that the surface layer regeneration mechanism was purely mechanical and associated with movement of GAGs and lipids through the cartilage matrix during deformation, since the experimental set-up did not contain any means of biochemical activation.
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Affiliation(s)
- S Graindorge
- Institute of Medical and Biological Engineering, University of Leeds, UK.
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Sabaratnam S, Mason RM, Levick JR. Hyaluronan molecular reflection by synovial lining is concentration dependent and reduced in dilute effusions in a rabbit model. ACTA ACUST UNITED AC 2006; 54:1673-81. [PMID: 16646039 DOI: 10.1002/art.21803] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Hyaluronan (HA) has a major role in regulating synovial fluid volume. This role depends on the synovium functioning as an ultrafilter that reflects HA during trans-synovial fluid drainage. Reflection boosts the HA concentration on the membrane surface, leading to osmotic retention of synovial fluid ("buffering"). In arthritic effusions, however, HA concentration and osmotic buffering are greatly reduced. We tested the hypothesis that reflection is reduced (escape increased) when the HA concentration falls below the molecular entanglement concentration (C*). METHODS HA at 0.2 mg/ml (<C*) or 1.5 mg/ml (>C*) was infused continuously into rabbit knee joints to set up a steady trans-synovial filtration. Joint-derived lymph was sampled over 3 hours, and subsynovial fluid was sampled at the end of the 3-hour period. HA was quantified by high-performance liquid chromatography to evaluate the reflected fraction. C* was determined by viscometry. RESULTS Viscometry showed that 0.2 mg/ml HA was below C* and 1.5 mg/ml was above it. At 0.2 mg/ml, the mean +/- SEM HA reflected fraction was 0.66 +/- 0.04 (n = 7). At 1.5 mg/ml the reflection increased to 0.88 +/- 0.04 (n = 5) (P < 0.005). HA permeation increased almost 3-fold, from 12% to 34%, at the lower concentration. CONCLUSION Chain-chain interaction at >C* increases effective molecular domain size and hence HA reflection, promoting effective conservation of synovial fluid in normal joints. HA can fall below C* (approximately 1 mg/ml) in arthritic effusions, promoting loss of HA. The attendant failure of outflow buffering facilitates fluid escape and periarticular edema.
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Affiliation(s)
- S Sabaratnam
- St. George's Hospital Medical School, London, UK
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Naka MH, Morita Y, Ikeuchi K. Influence of proteoglycan contents and of tissue hydration on the frictional characteristics of articular cartilage. Proc Inst Mech Eng H 2005; 219:175-82. [PMID: 15934393 DOI: 10.1243/095441105x34220] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this work, the hypothesis that water content and substances present on the articular surface play an important role in lubrication through the formation of a layer with a high content of water on the articular surface is analysed. The hydrophilic properties of proteoglycans exposed at the articular surface and hydration of tissue are the main responsible factors for the formation of this layer. The role of the articular surface in the frictional characteristics of articular cartilage was examined using specimens (femoral condyles of pigs) with intact and wiped surfaces tested in intermittent friction tests. Results indicated that the intact condition presented low friction in comparison with the wiped condition. The measured water loss of the articular cartilage after sliding and loading indicated a gradual decrease in the water content as the time evolved, and rehydration was observed after the submersion of unloaded specimens in the saline bath solution. Micrographic analyses indicated the presence of a layer covering the articular surface, and histological analyses indicated the presence of proteoglycans in this superficial layer. The hydration of the cartilage surface layer and proteoglycan in this layer influence lubrication.
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Affiliation(s)
- M H Naka
- Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.
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50
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Graindorge S, Ferrandez W, Jin Z, Ingham E, Grant C, Twigg P, Fisher J. Biphasic surface amorphous layer lubrication of articular cartilage. Med Eng Phys 2005; 27:836-44. [PMID: 16046176 DOI: 10.1016/j.medengphy.2005.05.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2004] [Revised: 05/22/2005] [Accepted: 05/24/2005] [Indexed: 11/26/2022]
Abstract
The biphasic nature of articular cartilage has been acknowledged for some time and is known to play an important role in many of the biomechanical functions performed by this unique tissue. From the lubrication point of view however, a simple biphasic model is unable to account for the extremely low friction coefficients that have been recorded experimentally, particularly during start-up. In addition, research over the last decade has indicated the presence of a surface amorphous layer on top of articular cartilage. Here, we present results from a finite element model of articular cartilage that includes a thin, soft, biphasic surface amorphous layer (BSAL). The results of this study show that a thin BSAL, with lower elastic modulus, dramatically altered the load sharing between the solid and liquid phases of articular cartilage, particularly in the near-surface regions of the underlying bulk cartilage and within the surface amorphous layer itself where the fluid load support exceeded 85%. By transferring the load from the solid phase to the fluid phase, the biphasic surface layer improves lubrication and reduces friction, whilst also protecting the underlying cartilage surface by 'shielding' the solid phase from elevated stresses. The increase in lubrication effectiveness is shown to be greatest during short duration loading scenarios, such as shock loads.
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Affiliation(s)
- Simon Graindorge
- Institute of Medical and Biological Engineering, University of Leeds, Leeds LS2 9JT, UK.
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