https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Wed, 13 May 2026 13:13:35 GMT 2026-05-13T13:13:35Z http://hdl.handle.net/10985/15736 Subject Specific Finite Element Mesh Generation of the Pelvis from Biplanar X-ray Images: Application to 120 clinical cases FOUGERON, Nolwenn; MACRON, Aurélien; TRAVERT, Christophe; SKALLI, Wafa; ROHAN, Pierre-Yves; PILLET, Helene Several Finite Element (FE) models of the pelvis have been developed to comprehensively assess the onset of pathologies and for clinical and industrial applications. However, because of the difficulties associated with the creation of subject-specific FE mesh from CT scan and MR images, most of the existing models rely on the data of one given individual. Moreover, although several fast and robust methods have been developed for automatically generating tetrahedral meshes of arbitrary geometries, hexahedral meshes are still preferred today because of their distinct advantages but their generation remains an open challenge. Recently, approaches have been proposed for fast 3D reconstruction of bones based on X-ray imaging. In this study, we adapted such an approach for the fast and automatic generation of all-hexahedral subject-specific FE models of the pelvis based on the elastic registration of a generic mesh to the subject-specific target in conjunction with element regularity and quality correction. The technique was successfully tested on a database of 120 3D reconstructions of pelvises from biplanar X-ray images. For each patient, a full hexahedral subject-specific FE mesh was generated with an accurate surface representation. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/15736 2018-01-01T00:00:00Z FOUGERON, Nolwenn MACRON, Aurélien TRAVERT, Christophe SKALLI, Wafa ROHAN, Pierre-Yves PILLET, Helene Several Finite Element (FE) models of the pelvis have been developed to comprehensively assess the onset of pathologies and for clinical and industrial applications. However, because of the difficulties associated with the creation of subject-specific FE mesh from CT scan and MR images, most of the existing models rely on the data of one given individual. Moreover, although several fast and robust methods have been developed for automatically generating tetrahedral meshes of arbitrary geometries, hexahedral meshes are still preferred today because of their distinct advantages but their generation remains an open challenge. Recently, approaches have been proposed for fast 3D reconstruction of bones based on X-ray imaging. In this study, we adapted such an approach for the fast and automatic generation of all-hexahedral subject-specific FE models of the pelvis based on the elastic registration of a generic mesh to the subject-specific target in conjunction with element regularity and quality correction. The technique was successfully tested on a database of 120 3D reconstructions of pelvises from biplanar X-ray images. For each patient, a full hexahedral subject-specific FE mesh was generated with an accurate surface representation. http://hdl.handle.net/10985/15735 Subject specific hexahedral Finite Element mesh generation of the pelvis from bi-Planar X-ray images FOUGERON, Nolwenn; SKALLI, Wafa; ROHAN, Pierre-Yves; PILLET, Helene Several Finite Element (FE) models of the pelvis have been developed to comprehensively assess the onset of pathologies and for clinical and industrial applications. However, because of the difficulties associated with the creation of subject-specific FE mesh from CT scan and MR images, most of the existing models rely on the data of one given individual. Moreover, although several fast and robust methods have been developed for automatically generating tetrahedral meshes of arbitrary geometries, hexahedral meshes are still preferred today because of their distinct advantages but their generation remains an open challenge. Recently, approaches have been proposed for fast 3D reconstruction of bones based on X-ray imaging. In this study, we adapted such an approach for the fast and automatic generation of all-hexahedral subject-specific FE models of the pelvis based on the elastic registration of a generic mesh to the subject-specific target in conjunction with element regularity and quality correction. A full hexahedral subject-specific FE mesh was generated with an accurate surface representation. Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/10985/15735 2017-01-01T00:00:00Z FOUGERON, Nolwenn SKALLI, Wafa ROHAN, Pierre-Yves PILLET, Helene Several Finite Element (FE) models of the pelvis have been developed to comprehensively assess the onset of pathologies and for clinical and industrial applications. However, because of the difficulties associated with the creation of subject-specific FE mesh from CT scan and MR images, most of the existing models rely on the data of one given individual. Moreover, although several fast and robust methods have been developed for automatically generating tetrahedral meshes of arbitrary geometries, hexahedral meshes are still preferred today because of their distinct advantages but their generation remains an open challenge. Recently, approaches have been proposed for fast 3D reconstruction of bones based on X-ray imaging. In this study, we adapted such an approach for the fast and automatic generation of all-hexahedral subject-specific FE models of the pelvis based on the elastic registration of a generic mesh to the subject-specific target in conjunction with element regularity and quality correction. A full hexahedral subject-specific FE mesh was generated with an accurate surface representation. http://hdl.handle.net/10985/18282 Combining Freehand Ultrasound-Based Indentation and Inverse Finite Element Modelling for the Identification of Hyperelastic Material Properties of Thigh Soft Tissues FOUGERON, Nolwenn; HEARING, Diane; ROSE, Jean-Loïc; BONNET, Xavier; ROHAN, Pierre-Yves; PILLET, Helene Finite Element Analysis (FEA) is a numerical modelling tool vastly employed in research facilities to analyse and predict load transmission between the human body and a medical device, such as a prosthesis or an exoskeleton. Yet, the use of Finite Element Modelling (FEM) in a framework compatible with clinical constraints is hindered by, amongst others, heavy and time-consuming assessments of material properties. Ultrasound imaging opens new and unique opportunities for the assessment of in vivo material properties of soft tissues. Confident of these advances, a method combining a freehand ultrasound probe and a force sensor was developed in order to compute the hyperelastic constitutive parameters of the soft tissues of the thigh in both relaxed (R) and contracted (C) muscles configurations. Seven asymptomatic subjects were included for the experiment. Two operators in each configuration performed the acquisitions. Inverse FEM allowed for the optimisation of an Ogden’s hyperelastic constitutive model of soft tissues of the thigh in large displacement. The mean shear modulus identified for configurations R and C were respectively 3.2 ± 1.3 kPa and 13.7 ± 6.5 kPa. The mean alpha parameter identified for configurations R and C were respectively 10 ± 1 and 9 ± 4. An analysis of variance showed that the configuration had an effect on constitutive parameters but not the operator. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/18282 2020-01-01T00:00:00Z FOUGERON, Nolwenn HEARING, Diane ROSE, Jean-Loïc BONNET, Xavier ROHAN, Pierre-Yves PILLET, Helene Finite Element Analysis (FEA) is a numerical modelling tool vastly employed in research facilities to analyse and predict load transmission between the human body and a medical device, such as a prosthesis or an exoskeleton. Yet, the use of Finite Element Modelling (FEM) in a framework compatible with clinical constraints is hindered by, amongst others, heavy and time-consuming assessments of material properties. Ultrasound imaging opens new and unique opportunities for the assessment of in vivo material properties of soft tissues. Confident of these advances, a method combining a freehand ultrasound probe and a force sensor was developed in order to compute the hyperelastic constitutive parameters of the soft tissues of the thigh in both relaxed (R) and contracted (C) muscles configurations. Seven asymptomatic subjects were included for the experiment. Two operators in each configuration performed the acquisitions. Inverse FEM allowed for the optimisation of an Ogden’s hyperelastic constitutive model of soft tissues of the thigh in large displacement. The mean shear modulus identified for configurations R and C were respectively 3.2 ± 1.3 kPa and 13.7 ± 6.5 kPa. The mean alpha parameter identified for configurations R and C were respectively 10 ± 1 and 9 ± 4. An analysis of variance showed that the configuration had an effect on constitutive parameters but not the operator. http://hdl.handle.net/10985/15788 In vivo identification of the mechanical properties of thigh tissues from FreeHand Ultrasound for the numerical investigation of loads at the socket/residual limb interface of amputee people FOUGERON, Nolwenn; BONNET, Xavier; ROSE, Jean-Loïc; ROHAN, Pierre-Yves; PILLET, Helene Prosthetic sockets are custom-designed and are decisive for functionality and comfort of limb prosthesis. To ensure load transmission and stability, high interface stresses are applied. Several computer models of the socket/residual limb assembly have been designed to identify critical stress accumulations that may induce discomfort or trauma. However, clinically relevant personalized Finite Element (FE) models represent a bottleneck. While material definition of tissues is critical for the evaluation of socket/tissues interactions, personalization of deep Soft Tissue (ST) material properties remains challenging. For clinical purpose, it has to be simple, in vivo and thus non-invasive. This work explores the feasibility of freehand ultrasound with an inverse method for assessing mechanical properties of the ST of the thigh. To be relevant for socket design, the residual strain from donning socket was simulated by compressing tissues (5% of initial circumference). Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/15788 2019-01-01T00:00:00Z FOUGERON, Nolwenn BONNET, Xavier ROSE, Jean-Loïc ROHAN, Pierre-Yves PILLET, Helene Prosthetic sockets are custom-designed and are decisive for functionality and comfort of limb prosthesis. To ensure load transmission and stability, high interface stresses are applied. Several computer models of the socket/residual limb assembly have been designed to identify critical stress accumulations that may induce discomfort or trauma. However, clinically relevant personalized Finite Element (FE) models represent a bottleneck. While material definition of tissues is critical for the evaluation of socket/tissues interactions, personalization of deep Soft Tissue (ST) material properties remains challenging. For clinical purpose, it has to be simple, in vivo and thus non-invasive. This work explores the feasibility of freehand ultrasound with an inverse method for assessing mechanical properties of the ST of the thigh. To be relevant for socket design, the residual strain from donning socket was simulated by compressing tissues (5% of initial circumference). http://hdl.handle.net/10985/21322 Prediction of muscle forces in residual limb during walking: comparison of transfemoral and Gritti–Stokes amputations FOUGERON, Nolwenn; BONNET, Xavier; PANHELLEUX, Brieuc; ROSE, Jean-Loïc; ROHAN, Pierre-Yves; PILLET, Helene Evaluation of muscle forces is relevant to understand walking strategies of amputated subjects. Such results could be implemented in finite element modelling to study the interaction between the residual limb and the socket by adding muscles to the model to improve pressure prediction at the interface. Further studies are needed to accurately estimate the percentage of vertical loads supported by the ischial support and to evaluate the results with, for example, EMG data. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/21322 2020-01-01T00:00:00Z FOUGERON, Nolwenn BONNET, Xavier PANHELLEUX, Brieuc ROSE, Jean-Loïc ROHAN, Pierre-Yves PILLET, Helene Evaluation of muscle forces is relevant to understand walking strategies of amputated subjects. Such results could be implemented in finite element modelling to study the interaction between the residual limb and the socket by adding muscles to the model to improve pressure prediction at the interface. Further studies are needed to accurately estimate the percentage of vertical loads supported by the ischial support and to evaluate the results with, for example, EMG data. http://hdl.handle.net/10985/21323 Femoral residuum/socket kinematics using fusion between 3D motion capture and stereo radiography PANHELLEUX, Brieuc; FOUGERON, Nolwenn; RUYSSEN, Nicolas; BONNET, Xavier; ROHAN, Pierre-Yves; PILLET, Helene Measurement of femur motion relative to the socket in gait in TF amputated patients can be a good indicator of prosthesis outcome. Our model, using low dose bi- planar radiography and motion capture, gives a prediction of femur motion (AA, EF, IER) in line with the sparse results found in the literature. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/21323 2020-01-01T00:00:00Z PANHELLEUX, Brieuc FOUGERON, Nolwenn RUYSSEN, Nicolas BONNET, Xavier ROHAN, Pierre-Yves PILLET, Helene Measurement of femur motion relative to the socket in gait in TF amputated patients can be a good indicator of prosthesis outcome. Our model, using low dose bi- planar radiography and motion capture, gives a prediction of femur motion (AA, EF, IER) in line with the sparse results found in the literature. http://hdl.handle.net/10985/26217 Effect of the ischial support on muscle force estimation during transfemoral walking FOUGERON, Nolwenn; BONNET, Xavier; PANHELLEUX, Brieuc; ROSE, Jean-Loïc; ROHAN, Pierre-Yves; PILLET, Hélène; PILLET, Helene Background: Transmission of loads between the prosthetic socket and the residual limb is critical for the comfort and walking ability of people with transfemoral amputation. This transmission is mainly determined by the socket tightening, muscle forces, and socket ischial support. However, numerical investigations of the amputated gait, using modeling approaches such as MusculoSkeletal (MSK) modeling, ignore the weight-bearing role of the ischial support. This simplification may lead to errors in the muscle force estimation. Objective: This study aims to propose a MSK model of the amputated gait that accounts for the interaction between the body and the ischial support for the estimation of the muscle forces of 13 subjects with unilateral transfemoral amputation. Methods: Contrary to previous studies on the amputated gait which ignored the interaction with the ischial support, here, the contact on the ischial support was included in the external loads acting on the pelvis in a MSK model of the amputated gait. Results: Including the ischial support induced an increase in the activity of the main abductor muscles, while adductor muscles' activity was reduced. These results suggest that neglecting the interaction with the ischial support leads to erroneous muscle force distribution considering the gait of people with transfemoral amputation. Although subjects with various bone geometries, particularly femur lengths, were included in the study, similar results were obtained for all subjects. Conclusions: Eventually, the estimation of muscle forces from MSK models could be used in combination with finite element models to provide quantitative data for the design of prosthetic sockets. Mon, 01 Apr 2024 00:00:00 GMT http://hdl.handle.net/10985/26217 2024-04-01T00:00:00Z FOUGERON, Nolwenn BONNET, Xavier PANHELLEUX, Brieuc ROSE, Jean-Loïc ROHAN, Pierre-Yves PILLET, Hélène PILLET, Helene Background: Transmission of loads between the prosthetic socket and the residual limb is critical for the comfort and walking ability of people with transfemoral amputation. This transmission is mainly determined by the socket tightening, muscle forces, and socket ischial support. However, numerical investigations of the amputated gait, using modeling approaches such as MusculoSkeletal (MSK) modeling, ignore the weight-bearing role of the ischial support. This simplification may lead to errors in the muscle force estimation. Objective: This study aims to propose a MSK model of the amputated gait that accounts for the interaction between the body and the ischial support for the estimation of the muscle forces of 13 subjects with unilateral transfemoral amputation. Methods: Contrary to previous studies on the amputated gait which ignored the interaction with the ischial support, here, the contact on the ischial support was included in the external loads acting on the pelvis in a MSK model of the amputated gait. Results: Including the ischial support induced an increase in the activity of the main abductor muscles, while adductor muscles' activity was reduced. These results suggest that neglecting the interaction with the ischial support leads to erroneous muscle force distribution considering the gait of people with transfemoral amputation. Although subjects with various bone geometries, particularly femur lengths, were included in the study, similar results were obtained for all subjects. Conclusions: Eventually, the estimation of muscle forces from MSK models could be used in combination with finite element models to provide quantitative data for the design of prosthetic sockets. http://hdl.handle.net/10985/22116 Finite element analysis of the stump-ischial containment socket interaction: a technical note FOUGERON, Nolwenn; ROHAN, Pierre-Yves; ROSE, Jean-Loïc; BONNET, Xavier; PILLET, Helene The role of the above-knee socket is to ensure the load transfer via the coupling of residual limb-prosthesis with minimal discomfort and without damaging the soft tissues. Modelling is a potential tool to predict socket fit prior to manufacture. However, state-of-the-art models only include the femur in soft tissues submitted to static loads neglecting the contribution of the hip joint. The hip joint is particularly challenging to model because it requires to compute the forces of muscles inserting on the residual limb. This work proposes a modelling of the hip joint including the estimation of muscular forces using a combined MusculoSKeletal (MSK)/Finite Element (FE) framework. An experimental-numerical approach was conducted on one femoral amputee subject. This allowed to i) model the hip joint and personalize muscles forces, ii) study the impact of the ischial support, and iii) evaluate the interface pressure. A reduction of the gluteus medius force from the MSK modelling was noticed when considering the ischial support. Interface pressure, predicted between 63 to 71 kPa, agreed with experimental literature data. The contribution of the hip joint is a key element of the modelling approach for the prediction of the socket interface pressure with the residual limb soft tissues. Fri, 01 Jul 2022 00:00:00 GMT http://hdl.handle.net/10985/22116 2022-07-01T00:00:00Z FOUGERON, Nolwenn ROHAN, Pierre-Yves ROSE, Jean-Loïc BONNET, Xavier PILLET, Helene The role of the above-knee socket is to ensure the load transfer via the coupling of residual limb-prosthesis with minimal discomfort and without damaging the soft tissues. Modelling is a potential tool to predict socket fit prior to manufacture. However, state-of-the-art models only include the femur in soft tissues submitted to static loads neglecting the contribution of the hip joint. The hip joint is particularly challenging to model because it requires to compute the forces of muscles inserting on the residual limb. This work proposes a modelling of the hip joint including the estimation of muscular forces using a combined MusculoSKeletal (MSK)/Finite Element (FE) framework. An experimental-numerical approach was conducted on one femoral amputee subject. This allowed to i) model the hip joint and personalize muscles forces, ii) study the impact of the ischial support, and iii) evaluate the interface pressure. A reduction of the gluteus medius force from the MSK modelling was noticed when considering the ischial support. Interface pressure, predicted between 63 to 71 kPa, agreed with experimental literature data. The contribution of the hip joint is a key element of the modelling approach for the prediction of the socket interface pressure with the residual limb soft tissues. http://hdl.handle.net/10985/21312 Evaluation of the Agreement Between Ultrasound-Based and Bi-Planar X-Ray Radiography-Based Assessment of the Geometrical Features of the Ischial Tuberosity in the Context of the Prevention of Seating-Related Pressure Injury BERRIOT, Audrey; FOUGERON, Nolwenn; BONNET, Xavier; PILLET, Helene; ROHAN, Pierre-Yves The proper management of the local mechanical environment within soft tissues is a key challenge central the prevention of Pressure Ulcers (PUs). Magnetic Resonance (MR) imaging is the preferred imaging modality to measure geometrical features associated with PUs. It is a very time-consuming method and it represents a major barrier to the clinical translation of risk assessment tools. There is a growing enthusiasm of the community for the use of B-mode ultrasound imaging as a practical, alternative technology suitable for bedside or outpatient clinic use. The objective was to evaluate the agreement between US-derived measurements and bi-planar X-ray radiography-derived measurements of geometrical features of the Ischial Tuberosity in a realistic loaded sitting position in healthy volunteers. The reproducibility of the US-based assessment of radii of curvature, evaluated in a subset of 4 subjects using the IS0 5725-2 framework was 1.7 mm and 1.3 mm in the in the frontal and sagittal plane respectively (95 % CI = 3.5 mm and = 2.6 mm respectively). Out of the 13 subjects included, the ischial tuberosity border was visible on the US image of 7 healthy subjects only. The mean of differences computed on the 7 subjects using Bland-Altman plots were +3.3 mm and -5.7 mm in the frontal and sagittal planes respectively. The corresponding 95% CI in the frontal and sagittal planes were respectively 1.8 mm and 3.7 mm. These differences however were not statistically significant (Wilcoxon signed-rank test). More effort is needed to establish and standardise optimal measurement procedures and test protocols for the assessment of geometrical features of the IT using US. Fri, 01 Jan 2021 00:00:00 GMT http://hdl.handle.net/10985/21312 2021-01-01T00:00:00Z BERRIOT, Audrey FOUGERON, Nolwenn BONNET, Xavier PILLET, Helene ROHAN, Pierre-Yves The proper management of the local mechanical environment within soft tissues is a key challenge central the prevention of Pressure Ulcers (PUs). Magnetic Resonance (MR) imaging is the preferred imaging modality to measure geometrical features associated with PUs. It is a very time-consuming method and it represents a major barrier to the clinical translation of risk assessment tools. There is a growing enthusiasm of the community for the use of B-mode ultrasound imaging as a practical, alternative technology suitable for bedside or outpatient clinic use. The objective was to evaluate the agreement between US-derived measurements and bi-planar X-ray radiography-derived measurements of geometrical features of the Ischial Tuberosity in a realistic loaded sitting position in healthy volunteers. The reproducibility of the US-based assessment of radii of curvature, evaluated in a subset of 4 subjects using the IS0 5725-2 framework was 1.7 mm and 1.3 mm in the in the frontal and sagittal plane respectively (95 % CI = 3.5 mm and = 2.6 mm respectively). Out of the 13 subjects included, the ischial tuberosity border was visible on the US image of 7 healthy subjects only. The mean of differences computed on the 7 subjects using Bland-Altman plots were +3.3 mm and -5.7 mm in the frontal and sagittal planes respectively. The corresponding 95% CI in the frontal and sagittal planes were respectively 1.8 mm and 3.7 mm. These differences however were not statistically significant (Wilcoxon signed-rank test). More effort is needed to establish and standardise optimal measurement procedures and test protocols for the assessment of geometrical features of the IT using US.