Implant Interface

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Guillaume Haiat - One of the best experts on this subject based on the ideXlab platform.

  • stress shielding at the bone Implant Interface influence of surface roughness and of the bone Implant contact ratio
    Journal of Orthopaedic Research, 2020
    Co-Authors: Maria Letizia Raffa, Vuhieu Nguyen, Philippe Hernigou, Charleshenri Flouzatlachaniette, Guillaume Haiat
    Abstract:

    Short and long-term stabilities of cementless Implants are strongly determined by the interfacial load transfer between Implants and bone tissue. Stress-shielding effects arise from shear stresses due to the difference of material properties between bone and the Implant. It remains difficult to measure the stress field in periprosthetic bone tissue. This study proposes to investigate the dependence of the stress field in periprosthetic bone tissue on i) the Implant surface roughness, ii) material properties of bone and of the Implant, iii) the bone-Implant contact ratio. To do so, a microscale 2-D finite element model of an osseointegrated bone-Implant Interface was developed where the surface roughness was modeled by a sinusoidal surface. The results show that the isostatic pressure is not affected by the presence of the bone-Implant Interface while shear stresses arise due to the combined effects of a geometrical singularity (for low surface roughness) and of shear stresses at the bone-Implant Interface (for high surface roughness). Stress-shielding effects are likely to be more important when the bone-Implant contact ratio value is low, which corresponds to a case of relatively low Implant stability. Shear stress reach a maximum value at a distance from the Interface comprised between 0 and 0.1 time roughness wavelength λ and tend to 0 at a distance from the Implant surface higher than λ, independently from bone-Implant contact ratio and waviness ratio. A comparison with an analytical model allows validating the numerical results. Future work should use the present approach to model osseointegration phenomena. This article is protected by copyright. All rights reserved.

  • stress shielding at the bone Implant Interface influence of surface roughness and of the bone Implant contact ratio
    Journal of Orthopaedic Research, 2020
    Co-Authors: Maria Letizia Raffa, Vuhieu Nguyen, Philippe Hernigou, Charleshenri Flouzatlachaniette, Guillaume Haiat
    Abstract:

    Short and long-term stabilities of cementless Implants are strongly determined by the interfacial load transfer between Implants and bone tissue. Stress-shielding effects arise from shear stresses due to the difference of material properties between bone and the Implant. It remains difficult to measure the stress field in periprosthetic bone tissue. This study proposes to investigate the dependence of the stress field in periprosthetic bone tissue on (i) the Implant surface roughness, (ii) the material properties of bone and of the Implant, (iii) the bone-Implant contact ratio. To do so, a microscale two-dimensional finite element model of an osseointegrated bone-Implant Interface was developed where the surface roughness was modeled by a sinusoidal surface. The results show that the isostatic pressure is not affected by the presence of the bone-Implant Interface while shear stresses arise due to the combined effects of a geometrical singularity (for low surface roughness) and of shear stresses at the bone-Implant Interface (for high surface roughness). Stress-shielding effects are likely to be more important when the bone-Implant contact ratio value is low, which corresponds to a case of relatively low Implant stability. Shear stress reach a maximum value at a distance from the Interface comprised between 0 and 0.1 time roughness wavelength λ and tend to 0 at a distance from the Implant surface higher than λ, independently from bone-Implant contact ratio and waviness ratio. A comparison with an analytical model allows validating the numerical results. Future work should use the present approach to model osseointegration phenomena.

  • Elastography of the bone-Implant Interface.
    Scientific reports, 2019
    Co-Authors: Yoann Hériveaux, Vuhieu Nguyen, Didier Geiger, Guillaume Haiat
    Abstract:

    The stress distribution around endosseous Implants is an important determinant of the surgical success. However, no method developed so far to determine the Implant stability is sensitive to the loading conditions of the bone-Implant Interface (BII). The objective of this study is to investigate whether a quantitative ultrasound (QUS) technique may be used to retrieve information on compressive stresses applied to the BII. An acousto-mechanical device was conceived to compress 18 trabecular bovine bone samples onto coin-shaped Implants and to measure the ultrasonic response of the BII during compression. The biomechanical behavior of the trabecular bone samples was modeled as Neo-Hookean. The reflection coefficient of the BII was shown to decrease as a function of the stress during the elastic compression of the trabecular bone samples and during the collapse of the trabecular network, with an average slope of −4.82 GPa−1. The results may be explained by an increase of the bone-Implant contact ratio and by changes of bone structure occurring during compression. The sensitivity of the QUS response of the BII to compressive stresses opens new paths in the elaboration of patient specific decision support systems allowing surgeons to assess Implant stability that should be developed in the future.

  • Biomechanical Behaviour of Bone-Implant Interface: A Review
    Journal of the Royal Society Interface, 2019
    Co-Authors: Xing Gao, Manon Fraulob, Guillaume Haiat
    Abstract:

    In recent decades, cementless Implants have been widely used in clinical practice to replace missing organs, to replace damaged or missing bone tissue or to restore joint functionality. However, there remain risks of failure which may have dramatic consequences. The success of an Implant depends on its stability, which is determined by the biomechanical properties of the bone–Implant Interface (BII). The aim of this review article is to provide more insight on the current state of the art concerning the evolution of the biomechanical properties of the BII as a function of the Implant's environment. The main characteristics of the BII and the determinants of Implant stability are first introduced. Then, the different mechanical methods that have been employed to derive the macroscopic properties of the BII will be described. The experimental multi-modality approaches used to determine the microscopic biomechanical properties of periprosthetic newly formed bone tissue are also reviewed. Eventually, the influence of the Implant's properties, in terms of both surface properties and biomaterials, is investigated. A better understanding of the phenomena occurring at the BII will lead to (i) medical devices that help surgeons to determine an Implant's stability and (ii) an improvement in the quality of Implants.

  • elastography of the bone-Implant Interface
    Scientific Reports, 2019
    Co-Authors: Yoann Hériveaux, Vuhieu Nguyen, Didier Geiger, Guillaume Haiat
    Abstract:

    the stress distribution around endosseous Implants is an important determinant of the surgical success. However, no method developed so far to determine the Implant stability is sensitive to the loading conditions of the bone-Implant Interface (Bii). the objective of this study is to investigate whether a quantitative ultrasound (QUS) technique may be used to retrieve information on compressive stresses applied to the BII. An acousto-mechanical device was conceived to compress 18 trabecular bovine bone samples onto coin-shaped Implants and to measure the ultrasonic response of the Bii during compression. the biomechanical behavior of the trabecular bone samples was modeled as Neo-Hookean. The reflection coefficient of the BII was shown to decrease as a function of the stress during the elastic compression of the trabecular bone samples and during the collapse of the trabecular network, with an average slope of −4.82 GPa −1. the results may be explained by an increase of the bone-Implant contact ratio and by changes of bone structure occurring during compression. the sensitivity of the QUS response of the Bii to compressive stresses opens new paths in the elaboration of patient specific decision support systems allowing surgeons to assess Implant stability that should be developed in the future. Endosseous cementless titanium Implants are now widely used in orthopedic, dental and maxillofacial surgeries 1,2. However, despite a routine clinical use, osseointegration failures still occur and may have dramatic consequences. The Implant surgical success is directly determined by the evolution of the biomechanical properties of the bone-Implant Interface (BII) 3-5. During surgery, endosseous Implants are inserted in a slightly undersized bone cavity formed by drilling or cutting, leading to a pre-stressed state of the bone-Implant system referred to as primary Implant stability. A compromise should be found between (i) insufficient primary stability leading to excessive interfacial micromotion following surgery 6-8 , which may imply Implant migration 9 and failure and (ii) excessive stresses at the BII, which may lead to bone necrosis 10,11. During healing, osseointegration phenomena, corresponding to an apposition of bone tissue around the Implant surface, are stimulated by "low level" stresses applied to the BII 12 , but excessive level of stresses may damage the consolidating BII and lead to Implant failure. As a consequence, the stress distribution around the Implant during and after surgery is an important determinant for the Implant success 13 , but it remains difficult to be assessed experimentally. X-ray based techniques 14 and magnetic resonance imaging 15 cannot be used to assess the level of stress at the BII due to diffraction phenomena related to the presence of metal. Therefore, biomechanical methods are needed. An interesting approach to assess the level of stress at the BII consists in employing finite element analysis (FEA). For example, stress and strain fields have been predicted around the BII in the context of dental 16,17 and orthopedic Implants applications 18. The results showed that stresses in the range of 0-10 MPa could be obtained at the BII, depending on the physiological boundary conditions. However, despite the progresses realized in computational analyses, it remains difficult to assess in a patient specific manner the loading conditions at the BII due to the complexity of the Implant geometry and of the bone material properties. Different biomechanical techniques have been developed to assess Implant stability. For example, percussion test methods based on the measurement of the contact duration between the Implant and the impacting device have been developed in the context of dental 19 and orthopedic surgery 20,21. The most commonly used biome-chanical technique is the resonance frequency analysis (RFA) 22 , which consists in measuring the first bending

Todd A Kuiken - One of the best experts on this subject based on the ideXlab platform.

  • a computational model for stress reduction at the skin Implant Interface of osseointegrated prostheses
    Journal of Biomedical Materials Research Part A, 2012
    Co-Authors: Srinivasu Yerneni, Yasin Y Dhaher, Todd A Kuiken
    Abstract:

    Osseointegrated Implants (OI)s for transfemoral prosthetic attachment offer amputees an alternative to the traditional socket attachment. Potential benefits include a natural transfer of loads directly to the skeleton via the percutaneous abutment, relief of pain and discomfort of residual limb soft tissues by eliminating sockets, increased sensory feedback, and improved function. Despite the benefits, the skin-Implant Interface remains a critical limitation, as it is highly prone to bacterial infection. One approach to improve clinical outcomes is to minimize stress concentrations at the skin-Implant Interface due to shear loading, reducing soft tissue breakdown and subsequent risk of infection. We hypothesized that broadening the bone base at the distal end of the femur would provide added surface area for skin adhesion and reduce stresses at the skin-Implant Interface. We tested this hypothesis using finite element models of an OI in a residual limb. Results showed a dramatic decrease in stress reduction, with up to ~90% decrease in stresses at the skin-Implant Interface as cortical bone thickness increased from 2 to 8 mm. The findings in this study suggests that surgical techniques could stabilize the skin-Implant Interface, thus enhancing a skin-to-bone seal around the percutaneous device and minimizing infection.

  • A computational model for stress reduction at the skin‐Implant Interface of osseointegrated prostheses
    Journal of biomedical materials research. Part A, 2012
    Co-Authors: Srinivasu Yerneni, Yasin Y Dhaher, Todd A Kuiken
    Abstract:

    Osseointegrated Implants (OI)s for transfemoral prosthetic attachment offer amputees an alternative to the traditional socket attachment. Potential benefits include a natural transfer of loads directly to the skeleton via the percutaneous abutment, relief of pain and discomfort of residual limb soft tissues by eliminating sockets, increased sensory feedback, and improved function. Despite the benefits, the skin-Implant Interface remains a critical limitation, as it is highly prone to bacterial infection. One approach to improve clinical outcomes is to minimize stress concentrations at the skin-Implant Interface due to shear loading, reducing soft tissue breakdown and subsequent risk of infection. We hypothesized that broadening the bone base at the distal end of the femur would provide added surface area for skin adhesion and reduce stresses at the skin-Implant Interface. We tested this hypothesis using finite element models of an OI in a residual limb. Results showed a dramatic decrease in stress reduction, with up to ~90% decrease in stresses at the skin-Implant Interface as cortical bone thickness increased from 2 to 8 mm. The findings in this study suggests that surgical techniques could stabilize the skin-Implant Interface, thus enhancing a skin-to-bone seal around the percutaneous device and minimizing infection.

Vincent Mathieu - One of the best experts on this subject based on the ideXlab platform.

  • biomechanical determinants of the stability of dental Implants influence of the bone Implant Interface properties
    Journal of Biomechanics, 2014
    Co-Authors: Vincent Mathieu, Romain Vayron, Gilles Richard, Gregory Lambert, Salah Naili, J P Meningaud, Guillaume Haiat
    Abstract:

    Abstract Dental Implants are now widely used for the replacement of missing teeth in fully or partially edentulous patients and for cranial reconstructions. However, risks of failure, which may have dramatic consequences, are still experienced and remain difficult to anticipate. The stability of biomaterials inserted in bone tissue depends on multiscale phenomena of biomechanical (bone–Implant interlocking) and of biological (mechanotransduction) natures. The objective of this review is to provide an overview of the biomechanical behavior of the bone–dental Implant Interface as a function of its environment by considering in silico , ex vivo and in vivo studies including animal models as well as clinical studies. The biomechanical determinants of osseointegration phenomena are related to bone remodeling in the vicinity of the Implants (adaptation of the bone structure to accommodate the presence of a biomaterial). Aspects related to the description of the Interface and to its space-time multiscale nature will first be reviewed. Then, the various approaches used in the literature to measure Implant stability and the bone–Implant Interface properties in vitro and in vivo will be described. Quantitative ultrasound methods are promising because they are cheap, non invasive and because of their lower spatial resolution around the Implant compared to other biomechanical approaches.

  • Biomechanical determinants of the stability of dental Implants: Influence of the bone–Implant Interface properties
    Journal of biomechanics, 2013
    Co-Authors: Vincent Mathieu, Romain Vayron, Gilles Richard, Gregory Lambert, Salah Naili, J P Meningaud, Guillaume Haiat
    Abstract:

    Dental Implants are now widely used for the replacement of missing teeth in fully or partially edentulous patients and for cranial reconstructions. However, risks of failure, which may have dramatic consequences, are still experienced and remain difficult to anticipate. The stability of biomaterials inserted in bone tissue depends on multiscale phenomena of biomechanical (bone-Implant interlocking) and of biological (mechanotransduction) natures. The objective of this review is to provide an overview of the biomechanical behavior of the bone-dental Implant Interface as a function of its environment by considering in silico, ex vivo and in vivo studies including animal models as well as clinical studies. The biomechanical determinants of osseointegration phenomena are related to bone remodeling in the vicinity of the Implants (adaptation of the bone structure to accommodate the presence of a biomaterial). Aspects related to the description of the Interface and to its space-time multiscale nature will first be reviewed. Then, the various approaches used in the literature to measure Implant stability and the bone-Implant Interface properties in vitro and in vivo will be described. Quantitative ultrasound methods are promising because they are cheap, non invasive and because of their lower spatial resolution around the Implant compared to other biomechanical approaches.

  • Echographic response of the bone-Implant Interface: dependence on healing time
    2012
    Co-Authors: Vincent Mathieu, Romain Vayron, Emmanuel Soffer, Fani Anagnostou, Guillaume Haiat
    Abstract:

    The effect of bone healing on the ultrasonic response of coin-shaped titanium Implants is investigated. Two groups of eight Implants were inserted on the tibiae of New Zealand White rabbits, each group corresponding to a healing duration (7 or 13 weeks). After the sacrifice, a 2-D scanning device was used in order to measure the ultrasonic response of the bone-Implant Interface in vitro at 15 MHz. The average value of the ratio r between the amplitudes of the echo of the bone-Implant Interface and of the water-Implant Interface was determined. Histological techniques were used to determine the fraction of Implant surface in contact with bone (BIC). The ultrasonic quantitative indicator r is significantly higher (p = 2.10-4) after seven weeks of healing time (r = 0.53) than after thirteen weeks (r= 0.49). The increase of mineralization of newly formed bone tissue and the increase of the BIC (from 27 % to 69 %) are responsible for the decrease of the gap of acoustical impedance at the bone-Implant Interface.

  • Influence of healing time on the ultrasonic response of the bone-Implant Interface.
    Ultrasound in medicine & biology, 2012
    Co-Authors: Vincent Mathieu, Romain Vayron, Emmanuel Soffer, Fani Anagnostou, Guillaume Haiat
    Abstract:

    The aim of the present study is to investigate the effect of bone healing on the ultrasonic response of coin-shaped titanium Implants inserted in rabbit tibiae. The ultrasound response of the Interface was measured in vitro at 15 MHz after 7 and 13 weeks of healing time. The average value of the ratio r between the amplitudes of the echo of the bone-Implant Interface and of the water-Implant Interface was determined. The bone-Implant contact (BIC) was measured by histomorphometry and the degree of mineralisation of bone was estimated qualitatively by histologic staining. The significant decrease of the ultrasonic quantitative indicator r (p = 2.10⁻⁴) vs. healing time (from r = 0.53 to r = 0.49) is explained by (1) the increase of the BIC (from 27% to 69%) and (2) the increase of mineralization of newly formed bone tissue, both phenomena inducing a decrease of the gap of acoustical impedance.

  • Influence of healing time on the echographic response of the bone-Implant Interface
    The Journal of the Acoustical Society of America, 2012
    Co-Authors: Vincent Mathieu, Romain Vayron, Emmanuel Soffer, Fani Anagnostou, Guillaume Haiat
    Abstract:

    The study aims at investigating the effect of bone healing on the ultrasonic response of coin-shaped titanium Implants. Sixteen Implants were inserted on the tibiae of rabbits. Two groups of eight samples were considered, each group corresponding to a healing duration (7 or 13 weeks). After the sacrifice, the ultrasonic response of the bone-Implant Interface was measured in vitro at 15 MHz with a 2-D scanning device. The average value of the ratio r between the amplitudes of the echo of the bone-Implant Interface and of the water-Implant Interface was determined. The fraction of Implant surface in contact with bone was measured by histomorphometry. The ultrasonic quantitative indicator r decreases significantly with healing time (p = 2.10-4, from r = 0.53 to r = 0.49). Two phenomena are responsible for the decrease of the gap of acoustical impedance at the bone-Implant Interface: i) the increase of mineralization of newly formed bone tissue and ii) the increase of the bone-Implant contact fraction (from 2...

Vuhieu Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • stress shielding at the bone Implant Interface influence of surface roughness and of the bone Implant contact ratio
    Journal of Orthopaedic Research, 2020
    Co-Authors: Maria Letizia Raffa, Vuhieu Nguyen, Philippe Hernigou, Charleshenri Flouzatlachaniette, Guillaume Haiat
    Abstract:

    Short and long-term stabilities of cementless Implants are strongly determined by the interfacial load transfer between Implants and bone tissue. Stress-shielding effects arise from shear stresses due to the difference of material properties between bone and the Implant. It remains difficult to measure the stress field in periprosthetic bone tissue. This study proposes to investigate the dependence of the stress field in periprosthetic bone tissue on i) the Implant surface roughness, ii) material properties of bone and of the Implant, iii) the bone-Implant contact ratio. To do so, a microscale 2-D finite element model of an osseointegrated bone-Implant Interface was developed where the surface roughness was modeled by a sinusoidal surface. The results show that the isostatic pressure is not affected by the presence of the bone-Implant Interface while shear stresses arise due to the combined effects of a geometrical singularity (for low surface roughness) and of shear stresses at the bone-Implant Interface (for high surface roughness). Stress-shielding effects are likely to be more important when the bone-Implant contact ratio value is low, which corresponds to a case of relatively low Implant stability. Shear stress reach a maximum value at a distance from the Interface comprised between 0 and 0.1 time roughness wavelength λ and tend to 0 at a distance from the Implant surface higher than λ, independently from bone-Implant contact ratio and waviness ratio. A comparison with an analytical model allows validating the numerical results. Future work should use the present approach to model osseointegration phenomena. This article is protected by copyright. All rights reserved.

  • stress shielding at the bone Implant Interface influence of surface roughness and of the bone Implant contact ratio
    Journal of Orthopaedic Research, 2020
    Co-Authors: Maria Letizia Raffa, Vuhieu Nguyen, Philippe Hernigou, Charleshenri Flouzatlachaniette, Guillaume Haiat
    Abstract:

    Short and long-term stabilities of cementless Implants are strongly determined by the interfacial load transfer between Implants and bone tissue. Stress-shielding effects arise from shear stresses due to the difference of material properties between bone and the Implant. It remains difficult to measure the stress field in periprosthetic bone tissue. This study proposes to investigate the dependence of the stress field in periprosthetic bone tissue on (i) the Implant surface roughness, (ii) the material properties of bone and of the Implant, (iii) the bone-Implant contact ratio. To do so, a microscale two-dimensional finite element model of an osseointegrated bone-Implant Interface was developed where the surface roughness was modeled by a sinusoidal surface. The results show that the isostatic pressure is not affected by the presence of the bone-Implant Interface while shear stresses arise due to the combined effects of a geometrical singularity (for low surface roughness) and of shear stresses at the bone-Implant Interface (for high surface roughness). Stress-shielding effects are likely to be more important when the bone-Implant contact ratio value is low, which corresponds to a case of relatively low Implant stability. Shear stress reach a maximum value at a distance from the Interface comprised between 0 and 0.1 time roughness wavelength λ and tend to 0 at a distance from the Implant surface higher than λ, independently from bone-Implant contact ratio and waviness ratio. A comparison with an analytical model allows validating the numerical results. Future work should use the present approach to model osseointegration phenomena.

  • Elastography of the bone-Implant Interface.
    Scientific reports, 2019
    Co-Authors: Yoann Hériveaux, Vuhieu Nguyen, Didier Geiger, Guillaume Haiat
    Abstract:

    The stress distribution around endosseous Implants is an important determinant of the surgical success. However, no method developed so far to determine the Implant stability is sensitive to the loading conditions of the bone-Implant Interface (BII). The objective of this study is to investigate whether a quantitative ultrasound (QUS) technique may be used to retrieve information on compressive stresses applied to the BII. An acousto-mechanical device was conceived to compress 18 trabecular bovine bone samples onto coin-shaped Implants and to measure the ultrasonic response of the BII during compression. The biomechanical behavior of the trabecular bone samples was modeled as Neo-Hookean. The reflection coefficient of the BII was shown to decrease as a function of the stress during the elastic compression of the trabecular bone samples and during the collapse of the trabecular network, with an average slope of −4.82 GPa−1. The results may be explained by an increase of the bone-Implant contact ratio and by changes of bone structure occurring during compression. The sensitivity of the QUS response of the BII to compressive stresses opens new paths in the elaboration of patient specific decision support systems allowing surgeons to assess Implant stability that should be developed in the future.

  • elastography of the bone-Implant Interface
    Scientific Reports, 2019
    Co-Authors: Yoann Hériveaux, Vuhieu Nguyen, Didier Geiger, Guillaume Haiat
    Abstract:

    the stress distribution around endosseous Implants is an important determinant of the surgical success. However, no method developed so far to determine the Implant stability is sensitive to the loading conditions of the bone-Implant Interface (Bii). the objective of this study is to investigate whether a quantitative ultrasound (QUS) technique may be used to retrieve information on compressive stresses applied to the BII. An acousto-mechanical device was conceived to compress 18 trabecular bovine bone samples onto coin-shaped Implants and to measure the ultrasonic response of the Bii during compression. the biomechanical behavior of the trabecular bone samples was modeled as Neo-Hookean. The reflection coefficient of the BII was shown to decrease as a function of the stress during the elastic compression of the trabecular bone samples and during the collapse of the trabecular network, with an average slope of −4.82 GPa −1. the results may be explained by an increase of the bone-Implant contact ratio and by changes of bone structure occurring during compression. the sensitivity of the QUS response of the Bii to compressive stresses opens new paths in the elaboration of patient specific decision support systems allowing surgeons to assess Implant stability that should be developed in the future. Endosseous cementless titanium Implants are now widely used in orthopedic, dental and maxillofacial surgeries 1,2. However, despite a routine clinical use, osseointegration failures still occur and may have dramatic consequences. The Implant surgical success is directly determined by the evolution of the biomechanical properties of the bone-Implant Interface (BII) 3-5. During surgery, endosseous Implants are inserted in a slightly undersized bone cavity formed by drilling or cutting, leading to a pre-stressed state of the bone-Implant system referred to as primary Implant stability. A compromise should be found between (i) insufficient primary stability leading to excessive interfacial micromotion following surgery 6-8 , which may imply Implant migration 9 and failure and (ii) excessive stresses at the BII, which may lead to bone necrosis 10,11. During healing, osseointegration phenomena, corresponding to an apposition of bone tissue around the Implant surface, are stimulated by "low level" stresses applied to the BII 12 , but excessive level of stresses may damage the consolidating BII and lead to Implant failure. As a consequence, the stress distribution around the Implant during and after surgery is an important determinant for the Implant success 13 , but it remains difficult to be assessed experimentally. X-ray based techniques 14 and magnetic resonance imaging 15 cannot be used to assess the level of stress at the BII due to diffraction phenomena related to the presence of metal. Therefore, biomechanical methods are needed. An interesting approach to assess the level of stress at the BII consists in employing finite element analysis (FEA). For example, stress and strain fields have been predicted around the BII in the context of dental 16,17 and orthopedic Implants applications 18. The results showed that stresses in the range of 0-10 MPa could be obtained at the BII, depending on the physiological boundary conditions. However, despite the progresses realized in computational analyses, it remains difficult to assess in a patient specific manner the loading conditions at the BII due to the complexity of the Implant geometry and of the bone material properties. Different biomechanical techniques have been developed to assess Implant stability. For example, percussion test methods based on the measurement of the contact duration between the Implant and the impacting device have been developed in the context of dental 19 and orthopedic surgery 20,21. The most commonly used biome-chanical technique is the resonance frequency analysis (RFA) 22 , which consists in measuring the first bending

Srinivasu Yerneni - One of the best experts on this subject based on the ideXlab platform.

  • a computational model for stress reduction at the skin Implant Interface of osseointegrated prostheses
    Journal of Biomedical Materials Research Part A, 2012
    Co-Authors: Srinivasu Yerneni, Yasin Y Dhaher, Todd A Kuiken
    Abstract:

    Osseointegrated Implants (OI)s for transfemoral prosthetic attachment offer amputees an alternative to the traditional socket attachment. Potential benefits include a natural transfer of loads directly to the skeleton via the percutaneous abutment, relief of pain and discomfort of residual limb soft tissues by eliminating sockets, increased sensory feedback, and improved function. Despite the benefits, the skin-Implant Interface remains a critical limitation, as it is highly prone to bacterial infection. One approach to improve clinical outcomes is to minimize stress concentrations at the skin-Implant Interface due to shear loading, reducing soft tissue breakdown and subsequent risk of infection. We hypothesized that broadening the bone base at the distal end of the femur would provide added surface area for skin adhesion and reduce stresses at the skin-Implant Interface. We tested this hypothesis using finite element models of an OI in a residual limb. Results showed a dramatic decrease in stress reduction, with up to ~90% decrease in stresses at the skin-Implant Interface as cortical bone thickness increased from 2 to 8 mm. The findings in this study suggests that surgical techniques could stabilize the skin-Implant Interface, thus enhancing a skin-to-bone seal around the percutaneous device and minimizing infection.

  • A computational model for stress reduction at the skin‐Implant Interface of osseointegrated prostheses
    Journal of biomedical materials research. Part A, 2012
    Co-Authors: Srinivasu Yerneni, Yasin Y Dhaher, Todd A Kuiken
    Abstract:

    Osseointegrated Implants (OI)s for transfemoral prosthetic attachment offer amputees an alternative to the traditional socket attachment. Potential benefits include a natural transfer of loads directly to the skeleton via the percutaneous abutment, relief of pain and discomfort of residual limb soft tissues by eliminating sockets, increased sensory feedback, and improved function. Despite the benefits, the skin-Implant Interface remains a critical limitation, as it is highly prone to bacterial infection. One approach to improve clinical outcomes is to minimize stress concentrations at the skin-Implant Interface due to shear loading, reducing soft tissue breakdown and subsequent risk of infection. We hypothesized that broadening the bone base at the distal end of the femur would provide added surface area for skin adhesion and reduce stresses at the skin-Implant Interface. We tested this hypothesis using finite element models of an OI in a residual limb. Results showed a dramatic decrease in stress reduction, with up to ~90% decrease in stresses at the skin-Implant Interface as cortical bone thickness increased from 2 to 8 mm. The findings in this study suggests that surgical techniques could stabilize the skin-Implant Interface, thus enhancing a skin-to-bone seal around the percutaneous device and minimizing infection.