The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Liam Blunt - One of the best experts on this subject based on the ideXlab platform.
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the influence of bone Cement type on production of fretting wear on the femoral stem Surface a preliminary study
Clinical Biomechanics, 2012Co-Authors: Hongyu Zhang, Liam Blunt, Xiangqian Jiang, Leigh Fleming, Simon BarransAbstract:BACKGROUND: It has been reported that bone Cement correlates with survivorship of Cemented total hip replaCement. However, little research has been published to investigate the influence of bone Cement type on production of fretting wear on the femoral stem. METHODS: In the present study, we performed six in vitro wear simulations using the same type of femoral stem (polished Exeter V40™) and three different bone Cements (Simplex P, Palacos R, and CMW 3). FINDINGS: Fretting wear was consistently reproduced on the stem Surface and the wear locations compared well with the results of retrieval studies. Selected 3D Surface parameters were utilised to quantitatively evaluate fretting wear and no significant difference was identified in terms of fretting wear severity between these simulations. The bone Cements were all badly damaged in those sites contacting the fretting wear areas on the femoral stem. Additionally, there were plenty of wear debris present on the Cement Surface, and the energy dispersive X-ray analysis confirmed that it was just Cement particles for Simplex P bone Cement, whilst it included metallic particles for Palacos R and CMW 3 bone Cements. INTERPRETATION: This preliminary study shed some light on the influence of bone Cement type on production of fretting wear on the femoral stem Surface but further research is needed to gain a better understanding on this issue.
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The contribution of the micropores in bone Cement Surface to generation of femoral stem wear in total hip replaCement
Tribology International, 2011Co-Authors: Hongyu Zhang, Leigh Brown, Liam Blunt, Xiangqian Jiang, Simon BarransAbstract:Abstract Although Cemented total hip replaCement has long been recognized as a situation that can lead to wear, the wear generated on the femoral stem has not been well documented, especially with regard to how this wear is initiated and propagated. This present work aimed to further investigate this issue based on a comprehensive study on Surface morphology of the femoral stem and the bone Cement, which were collected from seven in vitro wear simulations. It was shown that the wear locations on the stem Surface compared well with the results of retrieval studies, and the boundaries of the worn areas matched well the edges of the micropores present in the bone Cement Surface. This indicated that the micropores could potentially contribute to the generation of femoral stem wear. In addition, metallic debris was detected around the micropores from the simulation with increased loading cycles. However, no evidence of macro-cracks was observed across the Cement mantle in spite of the presence of micro-cracks initiated at the edge of the micropores. This study demonstrated a possible cause for progression of femoral stem wear and it may have an important bearing on the long term durability of Cemented hip prosthesis.
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Investigation of relative micromotion at the stem—Cement interface in total hip replaCement:
Proceedings of the Institution of Mechanical Engineers. Part H Journal of engineering in medicine, 2009Co-Authors: Hongyu Zhang, Leigh Brown, Liam Blunt, Simon Barrans, Xiangqian JiangAbstract:Cemented total hip replaCement has become a standard surgical technique to treat patients with osteoarthritis and osteonecrosis. The stem-Cement interface experiences fretting wear in vivo due to low-amplitude oscillatory micromotion under physiological loading, and this wear is currently becoming important as a potential mechanism for the overall wear of Cemented total hip replaCements. However, the relative micromotion at the stem-Cement interface has not been widely reported. In the present study, a new micromotion sensor is developed that is based on the deformation of a strain gauge, and this sensor is used to probe the migration of a polished Exeter stem within a Simplex P Cement mantle through an in vitro wear simulation. It is demonstrated that the stem migration value generally increases with an increase in the number of loading cycles, with a gradual decrease of migration rate. Additionally, fretting wear is successfully replicated on the stem Surface, and the micropores in the Cement Surface are considered to contribute to initiation and propagation of the fretting damage on the stem. This is confirmed by the observation that no evidence of fretting wear is detected on the stem where the Surface is in contact with the pore-free areas on the Cement. This study allows a deep insight into the micromotion at the stem-Cement interface, and provides evidence highlighting the significance of the micropores in the Cement Surface in the generation of fretting wear on a polished femoral stem.
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Static shear strength between polished stem and seven commercial acrylic bone Cements
Journal of Materials Science: Materials in Medicine, 2008Co-Authors: Hongyu Zhang, Leigh Brown, Liam BluntAbstract:The stem–Cement interface is one of the most significant sites in Cemented total hip replaCement and has long been implicated in failure of the whole joint system. However, shear strength at this interface has rarely been compared across a range of commercially available bone Cements. The present study seeks to address this issue by carrying out a comparative study. The results indicated that the static shear strength was more dependent on Cement type than Cement viscosity and volume. However, both Cement type and viscosity were contributory factors on porosity and micropore size in the Cement Surface. There was no significant difference between Simplex P and Simplex P with Tobramycin. Although the bone Cements were all hand mixed in this study, the static shear strength was significantly larger than the values recorded by other researchers, and the porosity and micropore size showed much lower values. Bone Cement transfer films were detected on the stem Surface, typically about 4–10 μm thick. They were considered to be an important factor contributing to high friction at the stem–Cement interface after initial debonding.
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paradigm shifts in Surface metrology part ii the current shift
Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences, 2007Co-Authors: Xiang Jiang, Paul J Scott, D J Whitehouse, Liam BluntAbstract:This is the second part of the paper ‘Paradigm shifts in Surface metrology’. In part I, the three historical paradigm shifts in Surface metrology were brought together, and the subsequent evolution resulting from the shifts discussed. The historical philosophy highlighted the fact that the paradigm shifts must be robust and flexible, meaning that Surface metrology must allow for full control of Surface manufacture and provide an understanding of the Surface functional performance. Part II presents the current paradigm shift as a ‘stepping stone’, building on the above historical context. Aspects of Surface geometry will also have to cater for Surfaces derived from disruptive application, i.e. structured and freeform Surfaces are identified candidates. The current shift is presented in three aspects: from profile to areal characterization; from stochastic to structured Surfaces; and from simple geometries to complex freeform geometries, all spanning the millimetre to sub-nanometre scales. In this paradigm shift, the scale of Surface texture is beginning to approach some of the geometrical features in micro/nano electro-mechanical systems devices and is becoming one of the most important functionality indicators. Part II will contextualize the current shifts in the discipline of Surface metrology, and Cement Surface metrology in place in the ultra precision and nanotechnology age.
Hongyu Zhang - One of the best experts on this subject based on the ideXlab platform.
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the influence of bone Cement type on production of fretting wear on the femoral stem Surface a preliminary study
Clinical Biomechanics, 2012Co-Authors: Hongyu Zhang, Liam Blunt, Xiangqian Jiang, Leigh Fleming, Simon BarransAbstract:BACKGROUND: It has been reported that bone Cement correlates with survivorship of Cemented total hip replaCement. However, little research has been published to investigate the influence of bone Cement type on production of fretting wear on the femoral stem. METHODS: In the present study, we performed six in vitro wear simulations using the same type of femoral stem (polished Exeter V40™) and three different bone Cements (Simplex P, Palacos R, and CMW 3). FINDINGS: Fretting wear was consistently reproduced on the stem Surface and the wear locations compared well with the results of retrieval studies. Selected 3D Surface parameters were utilised to quantitatively evaluate fretting wear and no significant difference was identified in terms of fretting wear severity between these simulations. The bone Cements were all badly damaged in those sites contacting the fretting wear areas on the femoral stem. Additionally, there were plenty of wear debris present on the Cement Surface, and the energy dispersive X-ray analysis confirmed that it was just Cement particles for Simplex P bone Cement, whilst it included metallic particles for Palacos R and CMW 3 bone Cements. INTERPRETATION: This preliminary study shed some light on the influence of bone Cement type on production of fretting wear on the femoral stem Surface but further research is needed to gain a better understanding on this issue.
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The contribution of the micropores in bone Cement Surface to generation of femoral stem wear in total hip replaCement
Tribology International, 2011Co-Authors: Hongyu Zhang, Leigh Brown, Liam Blunt, Xiangqian Jiang, Simon BarransAbstract:Abstract Although Cemented total hip replaCement has long been recognized as a situation that can lead to wear, the wear generated on the femoral stem has not been well documented, especially with regard to how this wear is initiated and propagated. This present work aimed to further investigate this issue based on a comprehensive study on Surface morphology of the femoral stem and the bone Cement, which were collected from seven in vitro wear simulations. It was shown that the wear locations on the stem Surface compared well with the results of retrieval studies, and the boundaries of the worn areas matched well the edges of the micropores present in the bone Cement Surface. This indicated that the micropores could potentially contribute to the generation of femoral stem wear. In addition, metallic debris was detected around the micropores from the simulation with increased loading cycles. However, no evidence of macro-cracks was observed across the Cement mantle in spite of the presence of micro-cracks initiated at the edge of the micropores. This study demonstrated a possible cause for progression of femoral stem wear and it may have an important bearing on the long term durability of Cemented hip prosthesis.
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Investigation of relative micromotion at the stem—Cement interface in total hip replaCement:
Proceedings of the Institution of Mechanical Engineers. Part H Journal of engineering in medicine, 2009Co-Authors: Hongyu Zhang, Leigh Brown, Liam Blunt, Simon Barrans, Xiangqian JiangAbstract:Cemented total hip replaCement has become a standard surgical technique to treat patients with osteoarthritis and osteonecrosis. The stem-Cement interface experiences fretting wear in vivo due to low-amplitude oscillatory micromotion under physiological loading, and this wear is currently becoming important as a potential mechanism for the overall wear of Cemented total hip replaCements. However, the relative micromotion at the stem-Cement interface has not been widely reported. In the present study, a new micromotion sensor is developed that is based on the deformation of a strain gauge, and this sensor is used to probe the migration of a polished Exeter stem within a Simplex P Cement mantle through an in vitro wear simulation. It is demonstrated that the stem migration value generally increases with an increase in the number of loading cycles, with a gradual decrease of migration rate. Additionally, fretting wear is successfully replicated on the stem Surface, and the micropores in the Cement Surface are considered to contribute to initiation and propagation of the fretting damage on the stem. This is confirmed by the observation that no evidence of fretting wear is detected on the stem where the Surface is in contact with the pore-free areas on the Cement. This study allows a deep insight into the micromotion at the stem-Cement interface, and provides evidence highlighting the significance of the micropores in the Cement Surface in the generation of fretting wear on a polished femoral stem.
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Static shear strength between polished stem and seven commercial acrylic bone Cements
Journal of Materials Science: Materials in Medicine, 2008Co-Authors: Hongyu Zhang, Leigh Brown, Liam BluntAbstract:The stem–Cement interface is one of the most significant sites in Cemented total hip replaCement and has long been implicated in failure of the whole joint system. However, shear strength at this interface has rarely been compared across a range of commercially available bone Cements. The present study seeks to address this issue by carrying out a comparative study. The results indicated that the static shear strength was more dependent on Cement type than Cement viscosity and volume. However, both Cement type and viscosity were contributory factors on porosity and micropore size in the Cement Surface. There was no significant difference between Simplex P and Simplex P with Tobramycin. Although the bone Cements were all hand mixed in this study, the static shear strength was significantly larger than the values recorded by other researchers, and the porosity and micropore size showed much lower values. Bone Cement transfer films were detected on the stem Surface, typically about 4–10 μm thick. They were considered to be an important factor contributing to high friction at the stem–Cement interface after initial debonding.
Josette Camilleri - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the hydration and bioactivity of radiopacified tricalcium silicate Cement, Biodentine and MTA Angelus
Dental Materials, 2013Co-Authors: Josette Camilleri, Fiodor Sorrentino, Denis DamidotAbstract:Objective: Novel root-end filling materials are composed of tricalcium silicate (TCS) and radiopacifier as opposed to the traditional mineral trioxide aggregate (MTA) which is made up of clinker derived from Portland Cement and bismuth oxide. The aim of this research was to characterize and investigate the hydration of a tricalcium silicate-based proprietary brand Cement (Biodentine™) and a laboratory manufactured Cement made with a mixture of tricalcium silicate and zirconium oxide (TCS-20-Z) and compare their properties to MTA Angelus™. Methods: The materials investigated included a Cement containing 80% of TCS and 20% zirconium oxide (TCS-20-Z), Biodentine™ and MTA Angelus™. The specific Surface area and the particle size distribution of the un-hydrated Cements and zirconium oxide were investigated using a gas adsorption method and scanning electron microscopy. Un-hydrated Cements and set materials were tested for mineralogy and microstructure, assessment of bioactivity and hydration. Scanning electron microscopy, X-ray energy dispersive analysis, X-ray fluorescence spectroscopy, X-ray diffraction, Rietveld refined X-ray diffraction and calorimetry were employed. The radiopacity of the materials was investigated using ISO 6876 methods. Results The un-hydrated Cements were composed of tricalcium silicate and a radiopacifier phase; zirconium oxide for both Biodentine™ and TCS-20-Z whereas bismuth oxide for MTA Angelus™. In addition Biodentine™ contained calcium carbonate particles and MTA Angelus™ exhibited the presence of dicalcium silicate, tricalcium aluminate, calcium, aluminum and silicon oxides. TCS and MTA Angelus™ exhibited similar specific Surface area while Biodentine™ had a greater specific Surface area. The Cements hydrated and produced some hydrates located either as reaction rim around the tricalcium silicate grain or in between the grains at the expense of volume containing the water initially present in the mixture. The rate of reaction of tricalcium calcium silicate was higher for Biodentine™ than for TCS-20-Z owing to its optimized particle size distribution, the presence of CaCO3 and the use of CaCl2. Tricalcium calcium silicate in MTA hydrated even more slowly than TCS-20-Z as evident from the size of reaction rim representative of calcium silicate hydrate (C-S-H) around tricalcium silicate grains and the calorimetry measurements. On the other hand, calcium oxide contained in MTA Angelus™ hydrated very fast inducing an intense exothermic reaction. Calcium hydroxide was produced as a by-product of reaction in all hydrated Cements but in greater quantities in MTA due to the hydration of calcium oxide. This lead to less dense microstructure than the one observed for both Biodentine™ and TCS-20-Z. All the materials were bioactive and allowed the deposition of hydroxyapatite on the Cement Surface in the presence of simulated body fluid and the radiopacity was greater than 3 mm aluminum thickness. Significance: All the Cement pastes tested were composed mainly of tricalcium silicate and a radiopacifier. The laboratory manufactured Cement contained no other additives. Biodentine™ included calcium carbonate which together with the additives in the mixing liquid resulted in a material with enhanced chemical properties relative to TCS-20-Z prototype Cement. On the other hand MTA Angelus™ displayed the presence of calcium, aluminum and silicon oxides in the un-hydrated powder. These phases are normally associated with the raw materials indicating that the clinker of MTA Angelus™ is incompletely sintered leading to a potential important variability in its mineralogy depending on the sintering conditions. As a consequence, the amount of tricalcium silicate is less than in the two other Cements leading to a slower reaction rate and more porous microstructure. © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
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Characterization and hydration kinetics of tricalcium silicate Cement for use as a dental biomaterial
Dental Materials, 2011Co-Authors: Josette CamilleriAbstract:Abstract Objectives Investigation and characterization of the replaCement of the Portland Cement component in mineral trioxide aggregate (MTA) with tricalcium silicate Cement which is manufactured using the sol-gel method from pure raw materials. Methods Tricalcium silicate and Portland Cement were characterized by viewing under the scanning electron microscope (SEM) and Surface imaging and elemental analysis with X-ray energy dispersive analysis (EDX), and by X-ray diffraction analysis with Rietveld refinement. In addition the hydration products of the material after 28 days of curing were evaluated by plotting atomic ratio plots from the EDX data. The Cement leachate was evaluated for pH and chemical composition by inductively coupled plasma. Results Portland Cement was composed of 68% tricalcium silicate. The tricalcium silicate Cement was 99% pure. On hydration both Cements produced calcium silicate hydrate and calcium hydroxide. The calcium hydroxide was leached in solution with higher leaching in HBSS. The leaching of calcium hydroxide in solution resulted in an alkaline pH. The reaction of calcium with the phosphorus present in HBSS resulting in the deposition of calcium phosphate on the Cement Surface. Significance Tricalcium silicate could prospectively replace the Portland Cement component in MTA.
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Characterization and hydration kinetics of tricalcium silicate Cement for use as a dental biomaterial
Dental Materials, 2011Co-Authors: Josette CamilleriAbstract:Objectives: Investigation and characterization of the replaCement of the Portland Cement component in mineral trioxide aggregate (MTA) with tricalcium silicate Cement which is manufactured using the sol-gel method from pure raw materials. Methods: Tricalcium silicate and Portland Cement were characterized by viewing under the scanning electron microscope (SEM) and Surface imaging and elemental analysis with X-ray energy dispersive analysis (EDX), and by X-ray diffraction analysis with Rietveld refinement. In addition the hydration products of the material after 28 days of curing were evaluated by plotting atomic ratio plots from the EDX data. The Cement leachate was evaluated for pH and chemical composition by inductively coupled plasma. Results: Portland Cement was composed of 68% tricalcium silicate. The tricalcium silicate Cement was 99% pure. On hydration both Cements produced calcium silicate hydrate and calcium hydroxide. The calcium hydroxide was leached in solution with higher leaching in HBSS. The leaching of calcium hydroxide in solution resulted in an alkaline pH. The reaction of calcium with the phosphorus present in HBSS resulting in the deposition of calcium phosphate on the Cement Surface. Significance: Tricalcium silicate could prospectively replace the Portland Cement component in MTA. ?? 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Simon Barrans - One of the best experts on this subject based on the ideXlab platform.
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the influence of bone Cement type on production of fretting wear on the femoral stem Surface a preliminary study
Clinical Biomechanics, 2012Co-Authors: Hongyu Zhang, Liam Blunt, Xiangqian Jiang, Leigh Fleming, Simon BarransAbstract:BACKGROUND: It has been reported that bone Cement correlates with survivorship of Cemented total hip replaCement. However, little research has been published to investigate the influence of bone Cement type on production of fretting wear on the femoral stem. METHODS: In the present study, we performed six in vitro wear simulations using the same type of femoral stem (polished Exeter V40™) and three different bone Cements (Simplex P, Palacos R, and CMW 3). FINDINGS: Fretting wear was consistently reproduced on the stem Surface and the wear locations compared well with the results of retrieval studies. Selected 3D Surface parameters were utilised to quantitatively evaluate fretting wear and no significant difference was identified in terms of fretting wear severity between these simulations. The bone Cements were all badly damaged in those sites contacting the fretting wear areas on the femoral stem. Additionally, there were plenty of wear debris present on the Cement Surface, and the energy dispersive X-ray analysis confirmed that it was just Cement particles for Simplex P bone Cement, whilst it included metallic particles for Palacos R and CMW 3 bone Cements. INTERPRETATION: This preliminary study shed some light on the influence of bone Cement type on production of fretting wear on the femoral stem Surface but further research is needed to gain a better understanding on this issue.
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The contribution of the micropores in bone Cement Surface to generation of femoral stem wear in total hip replaCement
Tribology International, 2011Co-Authors: Hongyu Zhang, Leigh Brown, Liam Blunt, Xiangqian Jiang, Simon BarransAbstract:Abstract Although Cemented total hip replaCement has long been recognized as a situation that can lead to wear, the wear generated on the femoral stem has not been well documented, especially with regard to how this wear is initiated and propagated. This present work aimed to further investigate this issue based on a comprehensive study on Surface morphology of the femoral stem and the bone Cement, which were collected from seven in vitro wear simulations. It was shown that the wear locations on the stem Surface compared well with the results of retrieval studies, and the boundaries of the worn areas matched well the edges of the micropores present in the bone Cement Surface. This indicated that the micropores could potentially contribute to the generation of femoral stem wear. In addition, metallic debris was detected around the micropores from the simulation with increased loading cycles. However, no evidence of macro-cracks was observed across the Cement mantle in spite of the presence of micro-cracks initiated at the edge of the micropores. This study demonstrated a possible cause for progression of femoral stem wear and it may have an important bearing on the long term durability of Cemented hip prosthesis.
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Investigation of relative micromotion at the stem—Cement interface in total hip replaCement:
Proceedings of the Institution of Mechanical Engineers. Part H Journal of engineering in medicine, 2009Co-Authors: Hongyu Zhang, Leigh Brown, Liam Blunt, Simon Barrans, Xiangqian JiangAbstract:Cemented total hip replaCement has become a standard surgical technique to treat patients with osteoarthritis and osteonecrosis. The stem-Cement interface experiences fretting wear in vivo due to low-amplitude oscillatory micromotion under physiological loading, and this wear is currently becoming important as a potential mechanism for the overall wear of Cemented total hip replaCements. However, the relative micromotion at the stem-Cement interface has not been widely reported. In the present study, a new micromotion sensor is developed that is based on the deformation of a strain gauge, and this sensor is used to probe the migration of a polished Exeter stem within a Simplex P Cement mantle through an in vitro wear simulation. It is demonstrated that the stem migration value generally increases with an increase in the number of loading cycles, with a gradual decrease of migration rate. Additionally, fretting wear is successfully replicated on the stem Surface, and the micropores in the Cement Surface are considered to contribute to initiation and propagation of the fretting damage on the stem. This is confirmed by the observation that no evidence of fretting wear is detected on the stem where the Surface is in contact with the pore-free areas on the Cement. This study allows a deep insight into the micromotion at the stem-Cement interface, and provides evidence highlighting the significance of the micropores in the Cement Surface in the generation of fretting wear on a polished femoral stem.
D J Whitehouse - One of the best experts on this subject based on the ideXlab platform.
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paradigm shifts in Surface metrology part ii the current shift
Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences, 2007Co-Authors: Xiang Jiang, Paul J Scott, D J Whitehouse, Liam BluntAbstract:This is the second part of the paper ‘Paradigm shifts in Surface metrology’. In part I, the three historical paradigm shifts in Surface metrology were brought together, and the subsequent evolution resulting from the shifts discussed. The historical philosophy highlighted the fact that the paradigm shifts must be robust and flexible, meaning that Surface metrology must allow for full control of Surface manufacture and provide an understanding of the Surface functional performance. Part II presents the current paradigm shift as a ‘stepping stone’, building on the above historical context. Aspects of Surface geometry will also have to cater for Surfaces derived from disruptive application, i.e. structured and freeform Surfaces are identified candidates. The current shift is presented in three aspects: from profile to areal characterization; from stochastic to structured Surfaces; and from simple geometries to complex freeform geometries, all spanning the millimetre to sub-nanometre scales. In this paradigm shift, the scale of Surface texture is beginning to approach some of the geometrical features in micro/nano electro-mechanical systems devices and is becoming one of the most important functionality indicators. Part II will contextualize the current shifts in the discipline of Surface metrology, and Cement Surface metrology in place in the ultra precision and nanotechnology age.