| 1. |
- Moreno, Silvia Suñer, et al.
(författare)
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Biological effects of wear particles generated in total joint replacements : trends and future prospects
- 2011
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Konferensbidrag (refereegranskat)abstract
- Joint replacements have considerably improved the quality of life of patients with joints damaged by disease or trauma. However, problems associated with wear particles generated due to the relative motion between the components of the bearing are still present and can lead to the eventual failure of the implant. The biological response to wear debris is directly related to prosthesis longevity. The identification of the mechanisms by which cells respond to wear debris and how particles distribute around the human body may provide valuable information for the long term success of artificial joints.During the last few decades, orthopaedic research has been focused on predicting the in vivo performance of joint replacements. However, the exact interrelationship between material physicochemical properties and inflammatory response is not fully understood to date. Laboratory wear simulators provide an accurate prediction of implant wear performance. However, particles generated from such wear simulators require validation to compare them with particles extracted from peri-implant tissues. The present work focuses initially on the advantages and disadvantages of the different bearing combinations (hard-on-soft and hard-on-hard bearings). In addition, the similarities between particles observed in vivo and those generated in vitro to predict the cellular response to wear debris is discussed. Finally, the biological effects of the degradation products generated by wear and corrosion are described.
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| 4. |
- Moreno, Silvia Suñer
(författare)
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Carbon reinforced UHMWPE composites for orthopaedic applications : characterization and biological response to wear particles
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Joint replacements have considerably improved the quality of life of patients with joints damaged by disease or trauma. However, problems associated with wear particles generated due to the relative motion between the components of the bearing are still present and can lead to the eventual failure of the implant. Ultra high molecular weight polyethylene (UHMWPE) has been extensively used as a bearing surface in total joint replacements. Although in the short- to medium term UHMWPE provides excellent clinical performance, in the longer term, problems associated with its high wear characteristics and biological responses to polyethylene wear particles leads to the failure of the implants.The first part of the thesis focuses on the current status of total joint replacements (hard-on-soft and hard-on-hard bearings), with particular attention on implant wear debris and the biological response to wear debris, as well as on the tribological behaviour of the potential materials currently under investigation. The aim of the second part of the thesis consists of an analysis of the wear rate and the size and volume distributions, morphology and biocompatibility of the wear debris generated from a multiwalled carbon nanotube (MWCNT) reinforced polyethylene material compared with conventional UHMWPE. The results showed that MWCNT’s can improve the characteristics of UHMWPE, in terms of both wear rate and biocompatibility. UHMWPE-MWCNT composite material was shown to generate low wear rates and a reduced osteolytic and cytotoxic potential compared to conventional virgin polyethylene of the same grade.The final part of the thesis focuses on the possibilities of graphene oxide (GO) as reinforcement of UHMWPE. The aim of this work is to investigate the manufacturing procedure to prepare a homogeneous UHMWPE/GO composite under optimised conditions that might improve the performance of UHMWPE in artificial joints. In this study, composites prepared under different mixing conditions were thermally and morphologically characterised and compared with conventional UHMWPE. The results showed that, under optimized manufacturing conditions, GO has the ability to improve the performance of conventional UHMWPE. This thesis has provided an insight into the potential of carbon based composites as an alternative to conventional UHMWPE for use in total joint replacements and further work concerning the influence of graphene oxide on the tribological performance of UHMWPE/GO composites is currently under investigation.
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| 5. |
- Moreno, Silvia Suñer
(författare)
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Investigation of Carbon Reinforced UHMWPE Nanocomposites for use in Orthopaedics
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Over the lifetime of a person, the function of the natural hip joint can be altered due to trauma or disease and an artificial hip replacement may eventually be required. Ultra high molecular weight polyethylene (UHMWPE) is considered the gold standard material for the acetabular cup in hip arthroplasties. However, problems associated with the release of UHMWPE wear particles, due to the relative motion between the bearing components, can lead to the eventual failure of the implant. The first part of this thesis focuses on reviewing the current status of total joint replacement research, with particular attention to implant bearing materials, implant wear particles and biological responses to wear particles. Subsequently, the thesis focuses on the potential of UHMWPE-based nanocomposites as an alternative to UHMWPE. A suitable method to prepare carbon nanoparticle reinforced UHMWPE materials was developed, and the possibilities of multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO) as reinforcements of UHMWPE were investigated.The results of this thesis showed that, under optimised conditions, carbonnanoparticles have the ability to improve the overall performance of UHMWPE,without adversely affecting the biocompatibility. However, further investigations into appropriate GO and MWCNT surface modification methods are necessary to enhance the filler/matrix interaction and further improve the performance of the resulting nanocomposites. This thesis has provided an insight into the potential of UHMWPE-based nanocomposites as an alternative to UHMWPE for use in total joint replacements and further work concerning biological and mechanical characterisation has been suggested in order to fully understand the behaviour of these nanocomposites.
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| 6. |
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| 7. |
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| 8. |
- Moreno, Silvia Suñer, et al.
(författare)
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UHMWPE/GO nanocomposites for orthopaedic applications: thermal, mechanical and tribological characterization
- 2014
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Konferensbidrag (refereegranskat)abstract
- Metal-on-Polyethylene (MoP) is the bearing combination most commonly used in total joint replacements. However, the degradative oxidation behaviour of ultra high molecular weight polyethylene (UHMWPE) leads to high amounts of wear debris, which contributes to the development of aseptic loosening and eventually to the failure of the implant. In order to address this issue, investigations have focused on the development of novel materials with improved characteristics. Recently, Graphene oxide (GO) has generated great interest as reinforcement for polymer matrices due to its excellent mechanical properties. The aim of this study was to investigate the possibilities of UHMWPE/GO nanocomposites for their use in joint implants.UHMWPE/GO nanocomposites with different wt% GO content, up to 2 wt%, were manufactured under optimised conditions using a ball milling technique. Thermal, mechanical and structural characterizations of the UHMWPE/GO nanocomposites and conventional UHMWPE were carried out by means of Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), uniaxial tensile tests and High Resolution Scanning Electron Microscopy (HR-SEM). Contact angle measurements were carried out to investigate the wettability of the materials. In addition, the tribological performance of the novel nanocomposites will be assessed with a six-station multidirectional pin on plate wear simulator under hip kinematics.The results showed that GO has the ability to improve the performance of conventional UHMWPE. The incorporation of GO enhanced the thermal stability and oxidative resistance of conventional UHMWPE. Under optimised conditions, the mechanical properties and wettability of the nanocomposites were also improved. These findings suggest that UHMWPE/GO nanocomposites might be an interesting alternative to conventional UHMWPE for their use in orthopaedic aplications and more research concerning the biocompatibility and tribological performance of this material is currently under investigation.
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| 9. |
- Sin, Jorge Rituerto, et al.
(författare)
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Fretting corrosion of Hafnium in Simulated Body Fluids
- 2014
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 75, s. 10-15
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Tidskriftsartikel (refereegranskat)abstract
- Hafnium has been suggested as an interesting material for biomedical applications due to its good biocompatibility and osteogenesis. However, its behaviour under fretting corrosion conditions, found in applications such as dental and joint implants, has not been studied in depth. A three-electrode electrochemical cell integrated with a ball-on-flat reciprocating tribometer was used to investigate the corrosion of hafnium and commercially pure (CP) titanium in simulated body fluids. An increased susceptibility to pitting corrosion was observed when hafnium was subjected to fretting. Open circuit potential measurements showed a more severe mechanical depassivation due to fretting in the case of CP titanium in comparison to hafnium. In addition, the anodic currents measured during potentiostatic tests were also higher for CP titanium.
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| 10. |
- Suñer, Silvia, et al.
(författare)
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Biological effects of wear particles generated in total joint replacements: trends and future prospects
- 2012
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Ingår i: Tribology - Materials, Surfaces & Interfaces. - 1751-5831 .- 1751-584X. ; 6:2, s. 39-52
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Forskningsöversikt (refereegranskat)abstract
- Joint replacements have considerably improved the quality of life of patients with joints damaged by disease or trauma. However, problems associated with wear particles generated due to the relative motion between the components of the bearing are still present and can lead to the eventual failure of the implant. The biological response to wear debris affects directly the longevity of the prosthesis. The identification of the mechanisms by which cells respond to wear debris and how particles distribute into the human body may provide valuable information for the long term success of artificial joints. During the last few decades, orthopaedic research has been focused on predicting the in vivo performance of joint replacements. However, the exact relationship between material physicochemical properties and inflammatory response has not been fully understood. Laboratory wear simulators provide an accurate prediction of implant wear performance. Though, particles generated from such wear simulators require validation to compare them with particles extracted from peri-implant tissues. This review focuses initially on the current status of total joint replacements (hard on soft and hard on hard bearings) as well as on the tribological behaviour of the potential materials currently under investigation. Then, the correspondence between particles observed in vivo and those generated in vitro to predict the cellular response to wear debris is discussed. Finally, the biological effects of the degradation products generated by wear and corrosion are described
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