Changes in pore morphology and fluid transport in compressed articular cartilage and the implications for joint lubrication

Greene, George W.; Zappone, Bruno; Zhao, Boxin; Söderman, Olle; Topgaard, Daniel; Rata, Gabriel; Israelachvili, Jacob N.

doi:10.1016/j.biomaterials.2008.07.046

Cited by 44 publications

(29 citation statements)

References 35 publications

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“…Type II collagen occupies 60-80% of the solid fraction of cartilage to form a porous fibril network (12,(36)(37)(38)(39) that governs the mechanical properties, deformation response, and friction of cartilage (30,40). The disruption of the fibril network and softening of cartilage have been observed at the onset and progression of OA (20,21), which could also be induced by applying type II collagenase (41,42).…”

Section: Resultsmentioning

confidence: 99%

Stick-slip friction and wear of articular joints

Lee¹,

Banquy²,

Israelachvili

2013

Proc. Natl. Acad. Sci. U.S.A.

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Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed regimes can be represented by friction maps-separating regimes of smooth and stick-slip sliding; damage generally occurs within the stick-slip regimes. Prolonged exposure of cartilage surfaces to stick-slip sliding resulted in a significant increase of surface roughness, indicative of severe morphological changes of the cartilage superficial zone. To further investigate the factors that are conducive to stick-slip and wear, we selectively digested essential components of cartilage: type II collagen, hyaluronic acid (HA), and glycosaminoglycans (GAGs). Compared with the normal cartilage, HA and GAG digestions modified the stick-slip behavior and increased surface roughness (wear) during sliding, whereas collagen digestion decreased the surface roughness. Importantly, friction forces increased up to 2, 10, and 5 times after HA, GAGs, and collagen digestion, respectively. Also, each digestion altered the friction map in different ways. Our results show that (i) wear is not directly related to the friction coefficient but (ii) more directly related to stick-slip sliding, even when present at small amplitudes, and that (iii) the different molecular components of joints work synergistically to prevent wear. Our results also suggest potential noninvasive diagnostic tools for sensing stick-slip in joints.arthritis | biolubrication | biointerface | boundary lubrication O steoarthritis (OA) is widely present in the elderly (1, 2) as well as people with obesity (3). Despite the prevalence of OA, the physical and biological events that trigger articular cartilage damage are still poorly understood, especially at the molecular and submicron levels; so far, no model has been successful in describing the mechanistic cascade that leads to cartilage wear and irreversible loss (4). There are no available techniques to detect the onset of joint diseases, and tracking the progression of these diseases remains a major challenge (5).One of the key challenges for establishing a model that can successfully track the cause and progression of joint diseases is in the fact that articular joints are designed to function under an extremely large range of mechanical, dynamic, and environmental conditions, under any of which a priori damage can occur. Many scientists have, therefore, focused their efforts on specific physiological regimes under which joints would be severely subjected to mechanical damage caused by a failure of the lubrication mechanism at the submicron level.The most important and also least understood physiological regime associated with damage is referred to as the boundary lubrication (BL) regime, where two sliding surfaces and the mo...

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Section: Resultsmentioning

confidence: 99%

Stick-slip friction and wear of articular joints

Lee¹,

Banquy²,

Israelachvili

2013

Proc. Natl. Acad. Sci. U.S.A.

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“…In this model, the unstressed, uncompressed pore structure of cartilage (Fig. 4A) is represented by coils of counter spiraling collagen fibrils arrayed normal to the fluid interface (14,15,24). HA molecules, decorated with aggrecans and cross-linked with LUB, are partially entangled in the collagen fibrils and partially extended into the interfacial fluid.…”

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

“…Because HA is known not to form any physical or covalent bonds or exhibit any adhesive interactions with cartilage's surface or internal collagen fibril pore network, the mechanism through which the necessary immobilization of HA chains is achieved is not immediately obvious. Recent reports describing the anisotropic changes to cartilage's pore network microstructure under compression suggests the HA immobilization could be achieved through a "mechanical trapping" mechanism by which entangled HA chains become trapped in the collapsing pore network of the deforming cartilage (14,15).In previous studies, lubricin (LUB) has been shown to adsorb to a wide variety of charged, uncharged, and hydrophobic surfaces and substrates (16) and to form aggregate complexes both with itself (17) and with free HA chains in solution (18) acting as a type of physical "cross-linking" agent*. Lubricin is thus expected to form cross-links with the surface-imobilized, partially entangled HA layer forming a cross-linked "HA-LUB complex" that is also expected to, under certain conditions, improve the The authors declare no conflict of interest.…”

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Adaptive mechanically controlled lubrication mechanism found in articular joints

Greene

Banquy²,

Lee³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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225

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Articular cartilage is a highly efficacious water-based tribological system that is optimized to provide low friction and wear protection at both low and high loads (pressures) and sliding velocities that must last over a lifetime. Although many different lubrication mechanisms have been proposed, it is becoming increasingly apparent that the tribological performance of cartilage cannot be attributed to a single mechanism acting alone but on the synergistic action of multiple "modes" of lubrication that are adapted to provide optimum lubrication as the normal loads, shear stresses, and rates change. Hyaluronic acid (HA) is abundant in cartilage and synovial fluid and widely thought to play a principal role in joint lubrication although this role remains unclear. HA is also known to complex readily with the glycoprotein lubricin (LUB) to form a cross-linked network that has also been shown to be critical to the wear prevention mechanism of joints. Friction experiments on porcine cartilage using the surface forces apparatus, and enzymatic digestion, reveal an "adaptive" role for an HA-LUB complex whereby, under compression, nominally free HA diffusing out of the cartilage becomes mechanically, i.e., physically, trapped at the interface by the increasingly constricted collagen pore network. The mechanically trapped HA-LUB complex now acts as an effective (chemically bound) "boundary lubricant"-reducing the friction force slightly but, more importantly, eliminating wear damage to the rubbing/shearing surfaces. This paper focuses on the contribution of HA in cartilage lubrication; however, the system as a whole requires both HA and LUB to function optimally under all conditions. arthritis | mechanical trapping | elastohydrodynamic lubrication | biointerface | biolubrication A rticular joints are almost completely sealed from their surroundings-by the synovial membrane around the joint and by cartilage and bone above and below the joint (1, 2). These barriers restrict rapid chemical transport into and out of joints, making it difficult to replace or repair damaged internal tissue or macromolecules, particularly those molecules that are covalently attached (bound) to the internal cartilage surfaces (1-3). Thus, it is no surprise that the major molecules involved in joint lubrication [lubricin and hyaluronic acid (HA)] are noncovalently bound and yet-to function as effective "boundary lubricants" that exhibit low friction and protect surfaces from wear-they need to act as if they are chemically bound to the surfaces.Hyaluronic acid has long been considered a potential boundary lubricant for cartilage (3-6), although numerous friction experiments have shown that solutions of free HA exhibit little lubrication activity (4, 5). However, surface forces apparatus (SFA) experiments (4) on chemically grafted and cross-linked HA layers demonstrated that such HA provide excellent wear protection for surfaces shearing at high pressures (200 atm), even though high friction coefficients (μ ¼ 0.15 − 0.3) were measured. These results...

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“…Multiple bones, each with unique interactions, associate in a specific manner to make movement of the hind foot. The articular cartilage layer and synovial fluid, which are surrounded by the joint capsule, have important role under impact loading and in high stress conditions (Greene et al, 2008;Caligaris and Ateshian, 2008;Ateshian, 2009). The joint capsule and ligaments provide stability to the joint.…”

Section: Introductionmentioning

confidence: 99%

Assessment of stress distribution in ankle joint: simultaneous application of experimental and finite element methods

Chitsazan¹,

Rouhi²,

Abbasi³

et al. 2015

IJECB

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Abstract:The goal of this study was to determine stress distribution in ankle joint by correlating with the strain distribution and its trend around tibia adjacent to the joint. Using an in-house device, an ankle from a cadaver was kept stable and loaded in various positions: neutral, dorsiflexion, plantar flexion, inversion and eversion. A total of six strain gauges were mounted around the shaft of the tibia, near the tibiotalar joint. This arrangement allowed us to measure deformations in the shaft of tibia. Patient-specific ankle joint geometry was generated from computed tomography data. The finite element model (FEM) of the ankle was validated using the experimental data logged by the strain gauges, and used for obtaining stress on the joint surface. A strong correlation was observed between the FEM and experimentally measured strains in magnitude (R = 0.94, P = 0.008), consequently stress distribution over the joint surface was obtained. 46A. Chitsazan et al.

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Changes in pore morphology and fluid transport in compressed articular cartilage and the implications for joint lubrication

Cited by 44 publications

References 35 publications

Stick-slip friction and wear of articular joints

Stick-slip friction and wear of articular joints

Adaptive mechanically controlled lubrication mechanism found in articular joints

Assessment of stress distribution in ankle joint: simultaneous application of experimental and finite element methods

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