A low friction, biphasic and boundary lubricating hydrogel for cartilage replacement

Milner, Piers; Parkes, Maria; Puetzer, Jennifer L.; Chapman, Robert; Stevens, Molly M.; Cann, P. M.; Jeffers, Jonathan R.T.

doi:10.1016/j.actbio.2017.11.002

Cited by 109 publications

(76 citation statements)

References 41 publications

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“…This directionality is lacking in most hydrogels, which should result in lower fluid load support. Although alternative theories exist for hydrogel lubrication (Dunn et al, 2014;Pitenis et al, 2014), biphasic theory including fluid load support is used for hydrogels as the basis for numerical studies (Baykal et al, 2013;Murakami et al, 2014) and fluid load support is used as explanation for the frictional behaviour in experimental work (Baykal et al, 2013;Milner et al, 2018). An increase of the friction coefficient over time is often seen as an indication for the presence and subsequent loss of fluid load support (Li et al, 2010;Murakami et al, 2014;Parkes et al, 2015), but friction measurements alone do not provide direct evidence for the load support mechanism.…”

Section: Lubrication Mechanisms In Ac and Hydrogelsmentioning

confidence: 99%

Fluid load support does not explain tribological performance of PVA hydrogels

Porte

Cann

Masen

2019

Journal of the Mechanical Behavior of Biomedical Materials

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The application of hydrogels as articular cartilage (AC) repair or replacement materials is limited by poor tribological behaviour, as it does not match that of native AC. In cartilage, the pressurisation of the interstitial fluid is thought to be crucial for the low friction as the load is shared between the solid and liquid phase of the material. This fluid load support theory is also often applied to hydrogels. However, this theory has not been validated as no experimental evidence directly relates the pressurisation of the interstitial fluid to the frictional response of hydrogels. This lack of understanding about the governing tribological mechanisms in hydrogels limits their optimised design. Therefore, this paper aims to provide a direct measure for fluid load support in hydrogels under physiologically relevant sliding conditions. A photoelastic method was developed to simultaneously measure the load on the solid phase of the hydrogel and its friction coefficient and thus directly relate friction and fluid load support. The results showed a clear distinction in frictional behaviour between the different test conditions, but results from photoelastic images and stressrelaxation experiments indicated that fluid load support is an unlikely explanation for the frictional response of the hydrogels. A more appropriate explanation, we hypothesized, is a non-replenished lubricant mechanism. This work has important implications for the tribology of cartilage and hydrogels as it shows that the existing theories do not adequately describe the tribological behaviour of hydrogels. The developed insights can be used to optimise the tribological performance of hydrogels as articular cartilage implants.

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Section: Lubrication Mechanisms In Ac and Hydrogelsmentioning

confidence: 99%

Fluid load support does not explain tribological performance of PVA hydrogels

Porte

Cann

Masen

2019

Journal of the Mechanical Behavior of Biomedical Materials

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“…Engineering materials with very low friction to mimic native cartilage is also an important consideration. [348] Finally, the degradation rate of these materials is another important design consideration. Tuning biomaterial degradation to coincide with tissue healing is possible with breakdown mechanisms involving hydrolytic degradation (polymer chemistries including esters, ureas, urethanes, amides) [67] or enzymatic degradation.…”

Section: Cartilage Biomaterialsmentioning

confidence: 99%

Biomaterials to Mimic and Heal Connective Tissues

2019

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Connective tissue is one of the four major types of animal tissue and plays essential roles throughout the human body. Genetic factors, aging, and trauma all contribute to connective tissue dysfunction and motivate the need for strategies to promote healing and regeneration. The goal of this Review is to link a fundamental understanding of connective tissues and their multiscale properties to better inform the design and translation of novel biomaterials to promote their regeneration. We discuss major clinical problems in adipose tissue, cartilage, dermis, and tendon that inspire the need to replace native connective tissue with biomaterials. We then detail multiscale structure-function relationships in native soft connective tissues that may be used to guide material design. Several biomaterials strategies to improve healing of these tissues that incorporate biologics and are biologic-free are reviewed. Finally, we highlight important guidance documents and standards (ASTM, FDA, EMA) that are important to consider for translating new biomaterials into clinical practice.

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“…All tests were performed at an average sliding velocity of 20 mm s À1 , which is a representative physiological condition with other studies identifying physiological sliding velocities varying between 1-60 mm s À1 . 16,17,38,39 Table 1 summarises the contact conditions of the tests. Stroke lengths ranging between 3-10 mm and 6-16 mm were used on the base and soft hydrogel respectively to perform tests for both migrating and overlapping conditions.…”

Section: Tribological Testingmentioning

confidence: 99%

“…The shear stress was reduced in the current work by reducing the polymer content. Choosing a different polymer will alter the frictional behaviour, 17,25 as this relates to polymeric interactions at the surface. A better understanding of how the surface chemistry of hydrogels affects the interfacial shear strength is required to enable a systematic optimisation of the tribo-system.…”

Section: General Applicability Of the Replenishment Theorymentioning

confidence: 99%

“…those using typical laboratory-based tribometer setups, are often performed employing a contact width of several millimetres. 16,17 The stroke length can therefore be of a similar order of magnitude to the contact width. For example, whilst investigating the effects of sliding velocity, Accardi et al 18 changed the stroke length of the reciprocating motion, and consequently changed the contact conditions from a migrating to an overlapping contact configuration, without specifically taking this into account.…”

Section: Introductionmentioning

confidence: 99%

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