The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
J O’byrne - One of the best experts on this subject based on the ideXlab platform.
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EFFECT OF VIBRATION ON SHEAR STRENGTH OF IMPACTED Bone GRAFT IN REVISION HIP SURGERY
2012Co-Authors: S Brennan, K Ryan, Dermot Brabazon, J O’byrneAbstract:Studies on soil mechanics have established that when vibration is applied to an aggregate, it results in more efficient alignment of particles and reduces the energy required to impact the aggregate. Our aim was to develop a method of applying vibration to the Bone impaction process and assess its effect on the mechanical properties of the impacted graft. Phase 1. Eighty bovine femoral heads were Milled using the Noviomagus Bone Mill. The graft was then washed using a pulsed lavage normal saline system over a sieve tower. A vibration impaction device was developed which housed two 15V DC motors with eccentric weights attached inside a metal cylinder. A weight was dropped onto this from a set height 72 times so as to replicate the Bone impaction process. A range of frequencies of vibration were tested, as measured using an accelerometer housed in the vibration chamber. Each shear test was then repeated at four different normal loads so as to generate a family of stress-strain curves. The Mohr-Coulomb failure envelope from which the shear strength and interlocking values are derived was plotted for each test. Phase 2. Experiments were repeated with the addition of blood so as to replicate a saturated environment as is encountered during operative conditions. Relatively dry graft impacted with the addition of vibration showed improved shear strength at all frequencies of vibration when compared to impaction without vibration. In our system the optimal frequency of vibration was 60 Hz. Under saturated conditions the addition of vibration is detrimental the shear strength of the aggregate. This is secondary to decreased interlocking between particles and may be explained by the process of liquefaction.
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Effect of vibration on the shear strength of impacted Bone graft in revision hip surgery
The Journal of Bone and Joint Surgery. British volume, 2011Co-Authors: Stephen A. Brennan, Dermot Brabazon, J O’byrneAbstract:Aims: Studies on soil mechanics have established that when vibration is applied to an aggregate, it results in more efficient alignment of particles and reduces the energy required to impact the aggregate. Our aim was to develop a method of applying vibration to the Bone impaction process and assess its impact on the mechanical properties of the impacted graft. Methods: Phase 1. Eighty bovine femoral heads were Milled using the Noviomagus Bone Mill. The graft was then washed using a pulsed lavage normal saline system over a sieve tower. A vibration impaction device was developed which housed two 15V DC motors with eccentric weights attached inside a metal cylinder. A weight was dropped onto this from a set height 72 times so as to replicate the Bone impaction process. A range of frequencies of vibration were tested, as measured using an accelerometer housed in the vibration chamber. Each shear test was then repeated at four different normal loads so as to generate a family of stress-strain curves. The Mohr-Coulomb failure envelope from which the shear strength and interlocking values are derived was plotted for each test. Phase 2. Experiments were repeated with the addition of blood so as to replicate a saturated environment as is encountered during operative conditions. Results Phase 1. Graft impacted with the addition of vibration at all frequencies of vibration showed improved shear strength when compared to impaction without vibration. Vibration at sixty Hertz was displayed the largest effect and was found to be significant. 3 Phase 2. Graft impacted with the addition of vibration in a saturated aggregate displayed lower shear strengths for all normal compressive loads than that of impaction without vibration. Conclusions Civil engineering principles hold true for the impaction Bone grafting procedure. In a dry aggregate the addition of vibration may be beneficial to the mechanical properties of the impacted graft. In our system the optimal frequency of vibration was 60 Hz. Under saturated conditions the addition of vibration is detrimental the shear strength of the aggregate. This may be explained by the process of liquefaction
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VIBRATION ASSISTED IMPACTION Bone GRAFTING.
2010Co-Authors: Stephen A. Brennan, Dermot Brabazon, J O’byrneAbstract:Introduction: At the time of revision hip surgery, large bony defects are often encountered. The traditional method of replacing this lost Bone is by the impaction Bone grafting technique. Vibration is commonly used in civil engineering to improve compaction of aggregate particles and to increase the compressive and shear strengths of the aggregate. Studies on soil mechanics have established that vibration applied to an aggregate results in more efficient alignment of particles and reduces the energy required to impact the aggregate. In this in-vitro study we have developed a novel method of applying vibration to the Bone impaction process. Methods: 60 Bovine femoral heads were cut into quarters and then Milled using the Noviomagnus manual Bone Mill. Fat and blood were then removed using a pulsed lavage normal saline system over a sieve tower. A vibration impaction device was developed which housed two 15V DC motors with eccentric weights attached inside a metal cylinder. A weight was dropped onto this from a set height 72 times so as to replicate the Bone impaction process. The Bone graft underlying this was thus impacted into a pellet, with or without the aid of vibration. A range of frequencies of vibration were tested, as measured using an accelerometer housed in the vibration chamber. Each shear test was then repeated at four different normal loads so as to generate a family of stress-strain graphs. The Mohr-Coulomb failure envelope from which the shear strength and interlocking vales are derived was plotted for each test. Results: Graft impacted with the addition of vibration at 60Hz was significantly more resistant to shearing force than graft impacted without vibration (p Conclusion: Civil engineering principles hold true for the impaction Bone grafting procedure. The best frequency of vibration to enhance the mechanical properties of the aggregate is in the region of 60Hz.
Stephen A. Brennan - One of the best experts on this subject based on the ideXlab platform.
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Effect of vibration on the shear strength of impacted Bone graft in revision hip surgery
The Journal of Bone and Joint Surgery. British volume, 2011Co-Authors: Stephen A. Brennan, Dermot Brabazon, J O’byrneAbstract:Aims: Studies on soil mechanics have established that when vibration is applied to an aggregate, it results in more efficient alignment of particles and reduces the energy required to impact the aggregate. Our aim was to develop a method of applying vibration to the Bone impaction process and assess its impact on the mechanical properties of the impacted graft. Methods: Phase 1. Eighty bovine femoral heads were Milled using the Noviomagus Bone Mill. The graft was then washed using a pulsed lavage normal saline system over a sieve tower. A vibration impaction device was developed which housed two 15V DC motors with eccentric weights attached inside a metal cylinder. A weight was dropped onto this from a set height 72 times so as to replicate the Bone impaction process. A range of frequencies of vibration were tested, as measured using an accelerometer housed in the vibration chamber. Each shear test was then repeated at four different normal loads so as to generate a family of stress-strain curves. The Mohr-Coulomb failure envelope from which the shear strength and interlocking values are derived was plotted for each test. Phase 2. Experiments were repeated with the addition of blood so as to replicate a saturated environment as is encountered during operative conditions. Results Phase 1. Graft impacted with the addition of vibration at all frequencies of vibration showed improved shear strength when compared to impaction without vibration. Vibration at sixty Hertz was displayed the largest effect and was found to be significant. 3 Phase 2. Graft impacted with the addition of vibration in a saturated aggregate displayed lower shear strengths for all normal compressive loads than that of impaction without vibration. Conclusions Civil engineering principles hold true for the impaction Bone grafting procedure. In a dry aggregate the addition of vibration may be beneficial to the mechanical properties of the impacted graft. In our system the optimal frequency of vibration was 60 Hz. Under saturated conditions the addition of vibration is detrimental the shear strength of the aggregate. This may be explained by the process of liquefaction
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VIBRATION ASSISTED IMPACTION Bone GRAFTING.
2010Co-Authors: Stephen A. Brennan, Dermot Brabazon, J O’byrneAbstract:Introduction: At the time of revision hip surgery, large bony defects are often encountered. The traditional method of replacing this lost Bone is by the impaction Bone grafting technique. Vibration is commonly used in civil engineering to improve compaction of aggregate particles and to increase the compressive and shear strengths of the aggregate. Studies on soil mechanics have established that vibration applied to an aggregate results in more efficient alignment of particles and reduces the energy required to impact the aggregate. In this in-vitro study we have developed a novel method of applying vibration to the Bone impaction process. Methods: 60 Bovine femoral heads were cut into quarters and then Milled using the Noviomagnus manual Bone Mill. Fat and blood were then removed using a pulsed lavage normal saline system over a sieve tower. A vibration impaction device was developed which housed two 15V DC motors with eccentric weights attached inside a metal cylinder. A weight was dropped onto this from a set height 72 times so as to replicate the Bone impaction process. The Bone graft underlying this was thus impacted into a pellet, with or without the aid of vibration. A range of frequencies of vibration were tested, as measured using an accelerometer housed in the vibration chamber. Each shear test was then repeated at four different normal loads so as to generate a family of stress-strain graphs. The Mohr-Coulomb failure envelope from which the shear strength and interlocking vales are derived was plotted for each test. Results: Graft impacted with the addition of vibration at 60Hz was significantly more resistant to shearing force than graft impacted without vibration (p Conclusion: Civil engineering principles hold true for the impaction Bone grafting procedure. The best frequency of vibration to enhance the mechanical properties of the aggregate is in the region of 60Hz.
Rolf Sandven - One of the best experts on this subject based on the ideXlab platform.
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Factors affecting stiffness properties in impacted morsellized Bone used in revision hip surgery: An experimental in vitro study
Journal of biomedical materials research. Part A, 2006Co-Authors: Lars Fosse, Helge Rønningen, Pål Benum, Stian Lydersen, Rolf SandvenAbstract:When revising loosened joint prosthesis, impacted morsellized Bone is frequently used as organic scaffolding. We studied the relative influence that different Bone particle size, impaction energy, and liquid content had on impacted Bone stiffness. Bovine Bone was morsellized in a Bone Mill by three grinding drums to produce Bone with different chip size distribution. Next, portions of Bone chips of controlled sizes were produced by a five-leveled sieve. Layer by layer of Bone are constructed into pellets by our experimental impaction method. This method allows us to vary one independent factor at a time in a controlled manner while keeping the other factors constant. Stiffness for all Bone pellets were measured during impaction and loading. In earlier studies, we focused on how impaction force, number of impaction strokes, and Bone liquid contents influence mechanical behavior. Here, we compare the outcome of all studies using general linear models. All five factors significantly contribute to stiffness of impacted morsellized Bone. Changing Bone moisture has major, while increasing the number of impaction strokes beyond five per layer has minor effect. Low water content is the main contributor to highest load stiffness. Optimal stability of impacted morsellized Bone is achieved with dried and well-graded particles. The number of heavy impaction strokes can be restricted.
Dermot Brabazon - One of the best experts on this subject based on the ideXlab platform.
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EFFECT OF VIBRATION ON SHEAR STRENGTH OF IMPACTED Bone GRAFT IN REVISION HIP SURGERY
2012Co-Authors: S Brennan, K Ryan, Dermot Brabazon, J O’byrneAbstract:Studies on soil mechanics have established that when vibration is applied to an aggregate, it results in more efficient alignment of particles and reduces the energy required to impact the aggregate. Our aim was to develop a method of applying vibration to the Bone impaction process and assess its effect on the mechanical properties of the impacted graft. Phase 1. Eighty bovine femoral heads were Milled using the Noviomagus Bone Mill. The graft was then washed using a pulsed lavage normal saline system over a sieve tower. A vibration impaction device was developed which housed two 15V DC motors with eccentric weights attached inside a metal cylinder. A weight was dropped onto this from a set height 72 times so as to replicate the Bone impaction process. A range of frequencies of vibration were tested, as measured using an accelerometer housed in the vibration chamber. Each shear test was then repeated at four different normal loads so as to generate a family of stress-strain curves. The Mohr-Coulomb failure envelope from which the shear strength and interlocking values are derived was plotted for each test. Phase 2. Experiments were repeated with the addition of blood so as to replicate a saturated environment as is encountered during operative conditions. Relatively dry graft impacted with the addition of vibration showed improved shear strength at all frequencies of vibration when compared to impaction without vibration. In our system the optimal frequency of vibration was 60 Hz. Under saturated conditions the addition of vibration is detrimental the shear strength of the aggregate. This is secondary to decreased interlocking between particles and may be explained by the process of liquefaction.
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Effect of vibration on the shear strength of impacted Bone graft in revision hip surgery
The Journal of Bone and Joint Surgery. British volume, 2011Co-Authors: Stephen A. Brennan, Dermot Brabazon, J O’byrneAbstract:Aims: Studies on soil mechanics have established that when vibration is applied to an aggregate, it results in more efficient alignment of particles and reduces the energy required to impact the aggregate. Our aim was to develop a method of applying vibration to the Bone impaction process and assess its impact on the mechanical properties of the impacted graft. Methods: Phase 1. Eighty bovine femoral heads were Milled using the Noviomagus Bone Mill. The graft was then washed using a pulsed lavage normal saline system over a sieve tower. A vibration impaction device was developed which housed two 15V DC motors with eccentric weights attached inside a metal cylinder. A weight was dropped onto this from a set height 72 times so as to replicate the Bone impaction process. A range of frequencies of vibration were tested, as measured using an accelerometer housed in the vibration chamber. Each shear test was then repeated at four different normal loads so as to generate a family of stress-strain curves. The Mohr-Coulomb failure envelope from which the shear strength and interlocking values are derived was plotted for each test. Phase 2. Experiments were repeated with the addition of blood so as to replicate a saturated environment as is encountered during operative conditions. Results Phase 1. Graft impacted with the addition of vibration at all frequencies of vibration showed improved shear strength when compared to impaction without vibration. Vibration at sixty Hertz was displayed the largest effect and was found to be significant. 3 Phase 2. Graft impacted with the addition of vibration in a saturated aggregate displayed lower shear strengths for all normal compressive loads than that of impaction without vibration. Conclusions Civil engineering principles hold true for the impaction Bone grafting procedure. In a dry aggregate the addition of vibration may be beneficial to the mechanical properties of the impacted graft. In our system the optimal frequency of vibration was 60 Hz. Under saturated conditions the addition of vibration is detrimental the shear strength of the aggregate. This may be explained by the process of liquefaction
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VIBRATION ASSISTED IMPACTION Bone GRAFTING.
2010Co-Authors: Stephen A. Brennan, Dermot Brabazon, J O’byrneAbstract:Introduction: At the time of revision hip surgery, large bony defects are often encountered. The traditional method of replacing this lost Bone is by the impaction Bone grafting technique. Vibration is commonly used in civil engineering to improve compaction of aggregate particles and to increase the compressive and shear strengths of the aggregate. Studies on soil mechanics have established that vibration applied to an aggregate results in more efficient alignment of particles and reduces the energy required to impact the aggregate. In this in-vitro study we have developed a novel method of applying vibration to the Bone impaction process. Methods: 60 Bovine femoral heads were cut into quarters and then Milled using the Noviomagnus manual Bone Mill. Fat and blood were then removed using a pulsed lavage normal saline system over a sieve tower. A vibration impaction device was developed which housed two 15V DC motors with eccentric weights attached inside a metal cylinder. A weight was dropped onto this from a set height 72 times so as to replicate the Bone impaction process. The Bone graft underlying this was thus impacted into a pellet, with or without the aid of vibration. A range of frequencies of vibration were tested, as measured using an accelerometer housed in the vibration chamber. Each shear test was then repeated at four different normal loads so as to generate a family of stress-strain graphs. The Mohr-Coulomb failure envelope from which the shear strength and interlocking vales are derived was plotted for each test. Results: Graft impacted with the addition of vibration at 60Hz was significantly more resistant to shearing force than graft impacted without vibration (p Conclusion: Civil engineering principles hold true for the impaction Bone grafting procedure. The best frequency of vibration to enhance the mechanical properties of the aggregate is in the region of 60Hz.
Hirotsugu Ohashi - One of the best experts on this subject based on the ideXlab platform.
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Factors Influencing the Stability of Stems Fixed with Impaction Graft in Vitro
Clinical Orthopaedics and Related Research®, 2009Co-Authors: Hirotsugu Ohashi, Masanori Matsuura, Tsuneyuki Ebara, Yusaku Okamoto, Hironori KouAbstract:Mechanical stability of the stem is believed to be an important factor in successful impaction grafting in revision THA. We asked whether particle size, femoral Bone deficiencies, stem design, graft composition, and impaction technique influenced the initial stability of the stem in vitro using model femora and human Bone particles. Bone particles made with a reciprocating blade-type Bone Mill contained larger particles with a broader size distribution than those made by a rotating drum-type Bone Mill and had higher stiffness on compression testing. The stiffness on torsional testing decreased as the degree of proximal-medial segmental deficiencies increased. The stiffness and maximum torque in a stem with a rectangular cross section and wide anteroposterior surface were higher in torsional tests. Adding hydroxyapatite granules to the Bone particles increased the torsional stability. To facilitate compact Bone particles, we developed a spacer between the guidewire and modified femoral packers. This spacer facilitated compacting Bone particles from the middle up to the proximal and the technique increased the amount of impacted Bone particles at the middle of the stem and also improved the initial stability of the stem. Stem design and degree of deficiencies influenced stiffness in the torsional test and the addition of hydroxyapatite granules enhanced torsional stiffness.
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FACTORS THAT INFLUENCE THE INITIAL STABILITY OF STEM FIXED WITH IMPACTED MORSELLIZED ALLOGRAFTS IN REVISION THA
2004Co-Authors: Hirotsugu Ohashi, Akio Kobayashi, Y. Kadoya, Yoshiki Yamano, Yuji TanabeAbstract:Impaction allografting is one of the techniques for reconstruction of femur during revision total hip arthroplasties. The initial stability of the stem fixed with impacted morsellized allogtafts and cement depends on multiple factors. The aim of this study was to investigate the stability of stem in reference to the size of Bone chips, femoral Bone defect and implant design. Morsellized grafts of human femoral heads were prepared using a reciprocating type Bone Mill or a rotating type Bone Mill. Femoral Bone defect was created at proximal medial cortex. Two types of polished stem were tested; CPT stem and VerSys CT stem (Zimmer Inc.). The cross section of the stem was relatively rectangular in CPT stem, while round in VerSys CT stem. Morsellized grafts were impacted into an over-reamed plastic Bone and the stem was fixed with PMMA Bone cement. Cyclic compression test and torsional test were performed using an Instron type machanical tester. Bone chips prepared by a reciprocating type Bone Mill contained large chips with broad size distribution, which represented high stiffness in compression test and high maximum torque in torsional test. Femoral Bone defect and implant geometry did not affect the axial stability of stem, while large Bone defect and round shape stem showed significantly lower maximum torque. These results indicated that the size of Bone chips, femoral Bone defect and implant geometry affected the initial stability of the stem. Impaction grafting seems to be a technically demanding procedure, however several factors can be controlled to obtain secure implant stability.
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Mechanical Properties of Impacted Human Morsellised Cancellous Allografts for Revision Joint Arthroplasty
Human Biomechanics and Injury Prevention, 2000Co-Authors: Yuji Tanabe, Hirotsugu Ohashi, Akio Kobayashi, Hiroshi Maki, Takashi Meguro, Yoshinori Kadoya, Yoshiki YamanoAbstract:This paper deals with the characterisation of mechanical properties of impacted morsellised cancellous allograft (IMCA) produced by dynamic compaction of allograft femoral heads ground by commercially available Bone Mills, i.e., rotating rasp, reciprocating blade and comb blade type Bone Mills. Various range and profile of particle sizes in the graft aggregates were obtained using these Bone Mills, and the effect of number of compaction as well as the distribution of particle sizes on the mechanical properties of IMCA under quasi-static compression and shear loading conditions was discussed. The morsellised cancellous allograft prepared by the reciprocating blade type Bone Mill showed a broad distribution of particle sizes, and gave IMCA superior mechanical properties to the graft with a more uniform size distribution, or prepared by the rotating rasp and comb blade type Bone Mills. The increase of number of compaction also improved the mechanical properties of IMCA in compression.