http://hdl.handle.net/10985/13597 Fri, 17 Apr 2026 03:04:40 GMT 2026-04-17T03:04:40Z http://hdl.handle.net/10985/19617 A Mechanical Descriptor of Instability in Human Locomotion: Experimental Findings in Control Subjects and People with Transfemoral Amputation AL ABIAD, Nahime; WATIER, Bruno; PILLET, Helene While multiple criteria to quantify gait instability exist, some limitations hinder their computation during realistic walking conditions. A descriptor, computed as the distance between the center of mass of the body and the minimal moment axis ( dCOM−Δ) , has been proposed recently. This present study aims at characterizing the behavior of the mentioned descriptor in a population at a higher risk of falls. Five individuals with transfemoral amputation and 14 healthy individuals were involved in an experiment composed of motion capture and force plates acquisition during overground walking at a self-selected speed. For both groups of participants, the profile of dCOM−Δ was analyzed and descriptive parameters were calculated. The plot of dCOM−Δ was different between groups and different relative to the leading limb considered (prosthetic or contralateral). All descriptive parameters calculated, except one, were statistically different between groups. As a conclusion, amputees seem to be able to limit the average of dCOM−Δ in spite of a different evolution pattern. This is consistent with the ability of the subjects to maintain their dynamic balance. However, the extracted parameters showed the significant asymmetry of the gait profile between prosthetic and contralateral stances and highlighted the potential sources of imbalance. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/19617 2020-01-01T00:00:00Z AL ABIAD, Nahime WATIER, Bruno PILLET, Helene While multiple criteria to quantify gait instability exist, some limitations hinder their computation during realistic walking conditions. A descriptor, computed as the distance between the center of mass of the body and the minimal moment axis ( dCOM−Δ) , has been proposed recently. This present study aims at characterizing the behavior of the mentioned descriptor in a population at a higher risk of falls. Five individuals with transfemoral amputation and 14 healthy individuals were involved in an experiment composed of motion capture and force plates acquisition during overground walking at a self-selected speed. For both groups of participants, the profile of dCOM−Δ was analyzed and descriptive parameters were calculated. The plot of dCOM−Δ was different between groups and different relative to the leading limb considered (prosthetic or contralateral). All descriptive parameters calculated, except one, were statistically different between groups. As a conclusion, amputees seem to be able to limit the average of dCOM−Δ in spite of a different evolution pattern. This is consistent with the ability of the subjects to maintain their dynamic balance. However, the extracted parameters showed the significant asymmetry of the gait profile between prosthetic and contralateral stances and highlighted the potential sources of imbalance. http://hdl.handle.net/10985/19815 A new comprehensive approach for bone remodeling under medium and high mechanical load based on cellular activity ALLENA, Rachele; GEORGE, Daniel; BOURZAC, Céline; PALLU, Stéphane; RÉMOND, Yves; BENSIDHOUM, Morad; PORTIER, Hugues Most of the last century, bone remodeling models have been proposed based on the observation that bone density is dependent on the intensity of the applied mechanical loads. Most of these cortical or trabecular bone remodeling models are related to the osteocyte mechanosensitivity, and they all have a direct correlation between the bone mineral density and the mechanical strain energy. However, experiments on human athletes show that high-intensity sport activity tends not to increase bone mineral density but rather has a negative impact. Therefore, it appears that the optimum bone mineral density would develop for “medium”-intensity activity (or medium mechanical loads) and not for the highest-intensity one. The authors would like to thank the CNRS for its financial support through the Défi Mécanobiologie to carry out the work. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/19815 2020-01-01T00:00:00Z ALLENA, Rachele GEORGE, Daniel BOURZAC, Céline PALLU, Stéphane RÉMOND, Yves BENSIDHOUM, Morad PORTIER, Hugues Most of the last century, bone remodeling models have been proposed based on the observation that bone density is dependent on the intensity of the applied mechanical loads. Most of these cortical or trabecular bone remodeling models are related to the osteocyte mechanosensitivity, and they all have a direct correlation between the bone mineral density and the mechanical strain energy. However, experiments on human athletes show that high-intensity sport activity tends not to increase bone mineral density but rather has a negative impact. Therefore, it appears that the optimum bone mineral density would develop for “medium”-intensity activity (or medium mechanical loads) and not for the highest-intensity one. http://hdl.handle.net/10985/19449 Cooperativity Scaling and Free Volume in Plasticized Polylactide ARAUJO, Steven; DELPOUVE, Nicolas; DOMENEK, Sandra; GUINAULT, Alain; GOLOVCHAK, Roman; SZATANIK, Roman; INGRAM, Adam; FAUCHARD, Cyrille; DELBREILH, Laurent; DARGENT, Eric The experimental evidence of the increase of activation energy associated with the super Arrhenius behavior governing amorphous polylactide by free volume variations has been obtained through a combination of calorimetric, dielectric, and positron annihilation lifetime measurements. The amount of free volume in polylactide was controlled by the amount of acetyltributylcitrate plasticizer in the composition. Plasticization is shown to decrease both the fragility index and the scale of cooperative motions at the glass transition. The calculations of volume and energetic components of kinetic fragility reveal that the fragility drop is governed by the change in the size of cooperative rearranging region. As a result, direct correlation has been established between cooperativity and activation energy for the entire plasticized polylactide series. It is also shown that cooperativity variations with both temperature and plasticizer content can be simplified as a master curve with free volume. The authors would like to thank the region Haute Normandie for their financial support and the acquisition of the Broadband Dielectric Spectrometer. R.G. acknowledges U.S. National Science Foundation (Grant no. DMR-1725188) for the acquisition of PAL spectrometer. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/19449 2019-01-01T00:00:00Z ARAUJO, Steven DELPOUVE, Nicolas DOMENEK, Sandra GUINAULT, Alain GOLOVCHAK, Roman SZATANIK, Roman INGRAM, Adam FAUCHARD, Cyrille DELBREILH, Laurent DARGENT, Eric The experimental evidence of the increase of activation energy associated with the super Arrhenius behavior governing amorphous polylactide by free volume variations has been obtained through a combination of calorimetric, dielectric, and positron annihilation lifetime measurements. The amount of free volume in polylactide was controlled by the amount of acetyltributylcitrate plasticizer in the composition. Plasticization is shown to decrease both the fragility index and the scale of cooperative motions at the glass transition. The calculations of volume and energetic components of kinetic fragility reveal that the fragility drop is governed by the change in the size of cooperative rearranging region. As a result, direct correlation has been established between cooperativity and activation energy for the entire plasticized polylactide series. It is also shown that cooperativity variations with both temperature and plasticizer content can be simplified as a master curve with free volume. http://hdl.handle.net/10985/19959 A Novel Classification of 3D Rib Cage Deformity in Subjects With Adolescent Idiopathic Scoliosis ASSI, Ayman; KARAM, Mohamad; SKALLI, Wafa; VERGARI, Claudio; VIALLE, Raphael; PIETTON, Raphael; BIZDIKIAN, Aren J.; KHARRAT, Khalil; DUBOUSSET, Jean; GHANEM, Ismat Study Design: This was a multicentric cross-sectional descriptive study. Objective: To analyze patterns of 3D rib cage deformity in subjects with adolescent idiopathic scoliosis (AIS) and their relationship with the spinal deformity. Summary of Background Data: Subjects with AIS present with rib cage deformity that can affect respiratory functions. The 3D rib cage deformities in AIS and their relationship to the spinal deformity are still unelucidated. Methods: A total of 200 AIS and 71 controls underwent low-dose biplanar x-rays and had their spine and rib cage reconstructed in 3-dimensional (D). Classic spinopelvic parameters were calculated in 3D and: rib cage gibbosity, thickness, width, volume and volumetric spinal penetration index (VSPI). Subjects with AIS were classified as: group I with mild rib cage deformity (n=88), group II with severe rib cage deformity (n=112) subgrouped into IIa (high gibbosity, n=48), IIb (high VSPI, n=48), and IIc (both high gibbosity and VSPI, n=16). Results: Groups IIa and IIb had a higher Cobb angle (33 vs. 54 degrees and 46 degrees, respectively) and torsion index (11 vs. 14 degrees and 13 degrees, respectively) than group I. Group IIb showed more severe hypokyphosis (IIb=21 degrees; IIa=33 degrees; I=36 degrees; control=42 degrees) with a reduced rib cage volume (IIb=4731 cm3; IIa=4985 cm3; I=5257 cm3; control=5254 cm3) and thickness (IIb=135 mm; IIa=148 mm; I=144 mm; control=144 mm). Group IIa showed an increasingly large local gibbosity descending from proximal to distal levels and did not follow the axial rotation of the spine. Group IIc showed characteristics of both groups IIa and IIb. Conclusions: This new classification of 3D rib cage deformity in AIS shows that the management of cases with high VSPI (groups IIb and IIc) should focus on restoring as much kyphosis as possible to avoid respiratory repercussions. Treatment indications in groups I and IIa would follow the consensual basic principles reported in the literature regarding bracing and surgery. Fri, 01 Jan 2021 00:00:00 GMT http://hdl.handle.net/10985/19959 2021-01-01T00:00:00Z ASSI, Ayman KARAM, Mohamad SKALLI, Wafa VERGARI, Claudio VIALLE, Raphael PIETTON, Raphael BIZDIKIAN, Aren J. KHARRAT, Khalil DUBOUSSET, Jean GHANEM, Ismat Study Design: This was a multicentric cross-sectional descriptive study. Objective: To analyze patterns of 3D rib cage deformity in subjects with adolescent idiopathic scoliosis (AIS) and their relationship with the spinal deformity. Summary of Background Data: Subjects with AIS present with rib cage deformity that can affect respiratory functions. The 3D rib cage deformities in AIS and their relationship to the spinal deformity are still unelucidated. Methods: A total of 200 AIS and 71 controls underwent low-dose biplanar x-rays and had their spine and rib cage reconstructed in 3-dimensional (D). Classic spinopelvic parameters were calculated in 3D and: rib cage gibbosity, thickness, width, volume and volumetric spinal penetration index (VSPI). Subjects with AIS were classified as: group I with mild rib cage deformity (n=88), group II with severe rib cage deformity (n=112) subgrouped into IIa (high gibbosity, n=48), IIb (high VSPI, n=48), and IIc (both high gibbosity and VSPI, n=16). Results: Groups IIa and IIb had a higher Cobb angle (33 vs. 54 degrees and 46 degrees, respectively) and torsion index (11 vs. 14 degrees and 13 degrees, respectively) than group I. Group IIb showed more severe hypokyphosis (IIb=21 degrees; IIa=33 degrees; I=36 degrees; control=42 degrees) with a reduced rib cage volume (IIb=4731 cm3; IIa=4985 cm3; I=5257 cm3; control=5254 cm3) and thickness (IIb=135 mm; IIa=148 mm; I=144 mm; control=144 mm). Group IIa showed an increasingly large local gibbosity descending from proximal to distal levels and did not follow the axial rotation of the spine. Group IIc showed characteristics of both groups IIa and IIb. Conclusions: This new classification of 3D rib cage deformity in AIS shows that the management of cases with high VSPI (groups IIb and IIc) should focus on restoring as much kyphosis as possible to avoid respiratory repercussions. Treatment indications in groups I and IIa would follow the consensual basic principles reported in the literature regarding bracing and surgery. http://hdl.handle.net/10985/19450 Simulation of laser-driven cratering experiments on aluminum AUBERT, Bertrand; HEBERT, David; RULLIER, Jean-Luc; LESCOUTE, Emilien; VIDEAU, Laurent; BERTHE, Laurent After a brief description of the physical principles involved in the cratering process, the authors present a specific methodology to simulate laser-driven cratering experiments performed with a long pulse duration (100 ns) and a small focal spot diameter (220 μ m). This methodology can be divided into two steps. First, the 2D-axisymmetrical pressure field generated by the laser on the target is determined from laser parameters. Second, this pressure is applied on the surface of the target in a Eulerian simulation. In order to validate this methodology, the authors simulate a laser shot on a thin aluminum target whose rear surface velocity is recorded by a VISAR (Velocity Interferometer System for Any Reflector). Once validated, they use the methodology to simulate laser-driven cratering experiments on semi-infinite aluminum targets. Numerical results are compared to experimental measurements of the craters. Although slight differences are pointed out and discussed, the proposed methodology is well adapted to simulate craterization laser shots. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/19450 2019-01-01T00:00:00Z AUBERT, Bertrand HEBERT, David RULLIER, Jean-Luc LESCOUTE, Emilien VIDEAU, Laurent BERTHE, Laurent After a brief description of the physical principles involved in the cratering process, the authors present a specific methodology to simulate laser-driven cratering experiments performed with a long pulse duration (100 ns) and a small focal spot diameter (220 μ m). This methodology can be divided into two steps. First, the 2D-axisymmetrical pressure field generated by the laser on the target is determined from laser parameters. Second, this pressure is applied on the surface of the target in a Eulerian simulation. In order to validate this methodology, the authors simulate a laser shot on a thin aluminum target whose rear surface velocity is recorded by a VISAR (Velocity Interferometer System for Any Reflector). Once validated, they use the methodology to simulate laser-driven cratering experiments on semi-infinite aluminum targets. Numerical results are compared to experimental measurements of the craters. Although slight differences are pointed out and discussed, the proposed methodology is well adapted to simulate craterization laser shots. http://hdl.handle.net/10985/19618 Liquid Metal Embrittlement, chapitre 22 AUGER, Thierry; VOGT, Jean-Bernard; PRORIOL SERRE, Ingrid If the terminology “hydrogen embrittlement” (HE) very explicitly points to the species responsible for the physical phenomenon, it is not the same for liquid metal embrittlement (LME). Whilst the first case suggests focusing on the presence of H+, H or H2, the second suggests that a priori all metals, provided that they are liquid, could lead to ductility loss. However, in terms of the literature, the number of articles dedicated to LME is much more modest than that dedicated to HE and accordingly the phenomena and the cases of LME are certainly less well known than those of HE. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/19618 2019-01-01T00:00:00Z AUGER, Thierry VOGT, Jean-Bernard PRORIOL SERRE, Ingrid If the terminology “hydrogen embrittlement” (HE) very explicitly points to the species responsible for the physical phenomenon, it is not the same for liquid metal embrittlement (LME). Whilst the first case suggests focusing on the presence of H+, H or H2, the second suggests that a priori all metals, provided that they are liquid, could lead to ductility loss. However, in terms of the literature, the number of articles dedicated to LME is much more modest than that dedicated to HE and accordingly the phenomena and the cases of LME are certainly less well known than those of HE. http://hdl.handle.net/10985/19993 Two Hybrid Approaches to Fatigue Modeling of Advanced-Sheet Molding Compounds (A-SMC) Composite AYARI, Houssem; IMADDAHEN, Amine; TAMBOURA, Sahbi; SHIRINBAYAN, Mohammadali; BEN DALI, Hachmi; TCHARKHTCHI, Abbas; FITOUSSI, Joseph To reinforce the environmental standards, we need to strengthen the lightening of vehicles and to generalize new composite materials in order to reduce weight. To use these innovative composite materials in the mass production of automotive parts, it is essential to propose a predictive approach of the S-N curves, which must be established for each new composite formulation and for several types of microstructure within real components. Although these preliminary characterizations consume time and money, this paper proposes two hybrid methodologies to predict the fatigue life during the fatigue test. Both methodologies are based on micromechanical modeling which is developed under monotonous loading with fatigue effects under different amplitudes. The suggested methodology is based on an experimental analysis of monotonic behavior under fatigue loading and on multi-scale modeling of damage. In the results, the proposed model and the used approaches are in good agreement with the experimental results. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/19993 2020-01-01T00:00:00Z AYARI, Houssem IMADDAHEN, Amine TAMBOURA, Sahbi SHIRINBAYAN, Mohammadali BEN DALI, Hachmi TCHARKHTCHI, Abbas FITOUSSI, Joseph To reinforce the environmental standards, we need to strengthen the lightening of vehicles and to generalize new composite materials in order to reduce weight. To use these innovative composite materials in the mass production of automotive parts, it is essential to propose a predictive approach of the S-N curves, which must be established for each new composite formulation and for several types of microstructure within real components. Although these preliminary characterizations consume time and money, this paper proposes two hybrid methodologies to predict the fatigue life during the fatigue test. Both methodologies are based on micromechanical modeling which is developed under monotonous loading with fatigue effects under different amplitudes. The suggested methodology is based on an experimental analysis of monotonic behavior under fatigue loading and on multi-scale modeling of damage. In the results, the proposed model and the used approaches are in good agreement with the experimental results. http://hdl.handle.net/10985/19482 Optimal strategy based on radiation chemistry for facile and direct synthesis of poly(3-thiophene acetic acid) polymers in water and dichloromethane BAHRY, Teseer; CUI, Zhenpeng; DENISET-BESSEAU, Ariane; GERVAIS, Matthieu; MBOMEKALLE, Israël; SOLLOGOUB, Cyrille; AUBERT, Pierre-Henri; BUI, Thanh-Tuân; REMITA, Samy In this work, synthesis of nanostructured conducting poly(3-thiophene acetic acid) (PTAA) polymers was developed by means of γ-induced oxidative polymerization of TAA monomers dissolved either in water or in dichloromethane. This synthesis was shown to be facile and directly feasible without any prior esterification of TAA and in the absence of oxidizing agents. Radiolytic yields of TAA oxidation as well as irradiation doses required for quantitative PTAA preparation were determined for each solvent. UV-Vis and ATR-FTIR spectroscopies demonstrated the successful formation of two PTAA polymers, so-called "PTAAH2O"and "PTAACH2Cl2". Size exclusion chromatography (SEC) highlighted convergent molecular weight values corresponding to approximately 13 monomer units. A similar behavior for both radio-synthesized PTAAs was monitored by thermogravimetric analysis (TGA). The morphological structures of PTAAH2O and PTAACH2Cl2 were analyzed in solution by Cryo-TEM and after deposition by SEM and AFM. Microscopic observations revealed the presence of two distinguishable nanostructures: nano-spherules of several hundreds of nanometers made of PTAAH2O and nano-granules of several tens of nanometers made of PTAACH2Cl2. Cyclic voltammetry analysis and the Tauc plot method were employed to calculate the electrical and optical band gaps. Both polymers possess similar electrical band gaps. However, PTAACH2Cl2 affords a lower optical band gap than PTAAH2O. Four-point probe measurements showed that the radio-synthesized PTAA polymers are characterized by interesting electrical properties: a higher electrical conductivity was nevertheless recorded for PTAACH2Cl2. This study highlights the powerful ability of the radiation chemistry-based methodology to lead, as a simple, versatile and reliable method, to nanostructured PTAA conducting polymers either in aqueous or organic solutions. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/19482 2020-01-01T00:00:00Z BAHRY, Teseer CUI, Zhenpeng DENISET-BESSEAU, Ariane GERVAIS, Matthieu MBOMEKALLE, Israël SOLLOGOUB, Cyrille AUBERT, Pierre-Henri BUI, Thanh-Tuân REMITA, Samy In this work, synthesis of nanostructured conducting poly(3-thiophene acetic acid) (PTAA) polymers was developed by means of γ-induced oxidative polymerization of TAA monomers dissolved either in water or in dichloromethane. This synthesis was shown to be facile and directly feasible without any prior esterification of TAA and in the absence of oxidizing agents. Radiolytic yields of TAA oxidation as well as irradiation doses required for quantitative PTAA preparation were determined for each solvent. UV-Vis and ATR-FTIR spectroscopies demonstrated the successful formation of two PTAA polymers, so-called "PTAAH2O"and "PTAACH2Cl2". Size exclusion chromatography (SEC) highlighted convergent molecular weight values corresponding to approximately 13 monomer units. A similar behavior for both radio-synthesized PTAAs was monitored by thermogravimetric analysis (TGA). The morphological structures of PTAAH2O and PTAACH2Cl2 were analyzed in solution by Cryo-TEM and after deposition by SEM and AFM. Microscopic observations revealed the presence of two distinguishable nanostructures: nano-spherules of several hundreds of nanometers made of PTAAH2O and nano-granules of several tens of nanometers made of PTAACH2Cl2. Cyclic voltammetry analysis and the Tauc plot method were employed to calculate the electrical and optical band gaps. Both polymers possess similar electrical band gaps. However, PTAACH2Cl2 affords a lower optical band gap than PTAAH2O. Four-point probe measurements showed that the radio-synthesized PTAA polymers are characterized by interesting electrical properties: a higher electrical conductivity was nevertheless recorded for PTAACH2Cl2. This study highlights the powerful ability of the radiation chemistry-based methodology to lead, as a simple, versatile and reliable method, to nanostructured PTAA conducting polymers either in aqueous or organic solutions. http://hdl.handle.net/10985/19935 Radiation-induced polymerization of 3-hexylthiophene in oxygen-free and oxygen-saturated dichloromethane solvent BAHRY, Teseer; CUI, Zhenpeng; DAZZI, Alexandre; GERVAIS, Matthieu; SOLLOGOUB, Cyrille; GOUBARD, Fabrice; BUI, Thanh-Tuân; REMITA, Samy As alternative radiolytic approach, the synthesis of P3HT was made possible thanks to the oxidation of 3HT monomers by chloromethyl and dichloromethyl radicals or by their corresponding peroxyl radicals in situ produced by dichloromethane solvent radiolysis. Under two different experimental conditions, in oxygen-free solution and in oxygen-saturated solution, two different polymers, “P3HTN2” and “P3HTO2” respectively, were successfully synthesized. Both produced materials were discerned by several analytical and spectroscopic techniques. UV–Vis absorption spectroscopy results showed that the radiolytic yield of 3HT oxidation in dichloromethane solvent is higher under O2 atmosphere. Indeed, a dose of 75 kGy was needed to polymerize 10 mM in 3HT under N2 atmosphere, meanwhile a dose of 35 kGy was sufficient to polymerize the same amount of 3HT under O2. The average molecular weight of P3HTO2was found higher than that of P3HTN2 as revealed by SEC chromatography analysis. Also, P3HTO2exhibits better thermal stability than P3HTN2. ATR-FTIR spectroscopy revealed the specific presence into P3HTO2 polymers of some functional groups such as carbonyl, hydroxyl and carboxyl moieties, which clearly explains the difference between the morphological structures of P3HTN2 and P3HTO2 as highlighted by cryo-TEM, SEM and AFM microscopies. Finally, both radio-synthesized P3HTN2 and P3HTO2 polymers were found characterized by remarkably significant conductive, electronic and optical properties. We thank Jean-Michel Guigner (IMPMC, Université Pierre et Marie Curie, France) for Cryo-TEM experiments. Fri, 01 Jan 2021 00:00:00 GMT http://hdl.handle.net/10985/19935 2021-01-01T00:00:00Z BAHRY, Teseer CUI, Zhenpeng DAZZI, Alexandre GERVAIS, Matthieu SOLLOGOUB, Cyrille GOUBARD, Fabrice BUI, Thanh-Tuân REMITA, Samy As alternative radiolytic approach, the synthesis of P3HT was made possible thanks to the oxidation of 3HT monomers by chloromethyl and dichloromethyl radicals or by their corresponding peroxyl radicals in situ produced by dichloromethane solvent radiolysis. Under two different experimental conditions, in oxygen-free solution and in oxygen-saturated solution, two different polymers, “P3HTN2” and “P3HTO2” respectively, were successfully synthesized. Both produced materials were discerned by several analytical and spectroscopic techniques. UV–Vis absorption spectroscopy results showed that the radiolytic yield of 3HT oxidation in dichloromethane solvent is higher under O2 atmosphere. Indeed, a dose of 75 kGy was needed to polymerize 10 mM in 3HT under N2 atmosphere, meanwhile a dose of 35 kGy was sufficient to polymerize the same amount of 3HT under O2. The average molecular weight of P3HTO2was found higher than that of P3HTN2 as revealed by SEC chromatography analysis. Also, P3HTO2exhibits better thermal stability than P3HTN2. ATR-FTIR spectroscopy revealed the specific presence into P3HTO2 polymers of some functional groups such as carbonyl, hydroxyl and carboxyl moieties, which clearly explains the difference between the morphological structures of P3HTN2 and P3HTO2 as highlighted by cryo-TEM, SEM and AFM microscopies. Finally, both radio-synthesized P3HTN2 and P3HTO2 polymers were found characterized by remarkably significant conductive, electronic and optical properties. http://hdl.handle.net/10985/19737 Spino-femoral muscles affect sagittal alignment and compensatory recruitment: a new look into soft tissues in adult spinal deformity BAO, Hongda; MOAL, Bertrand; VIRA, Shaleen; BRONSARD, Nicolas; AMABILE, Célia; ERRICO, Thomas; SCHWAB, Frank; SKALLI, Wafa; DUBOUSSET, Jean; LAFAGE, Virginie Objective To quantify muscle characteristics (volumes and fat infiltration) and identify their relationship to sagittal malalignment and compensatory mechanism recruitment. Methods Female adult spinal deformity patients underwent T1-weighted MRI with a 2-point Dixon protocol from the proximal tibia up to the T12 vertebra. 3D reconstructions of 17 muscles, including extensors and flexors of spine, hip and knee, were obtained. Muscle volume standardized by bone volume and percentage of fat infiltration (Pfat) were calculated. Correlations and regressions were performed. Results A total of 22 patients were included. Significant correlations were observed between sagittal alignment and muscle parameters. Fat infiltration of the hip and knee flexors and extensors correlated with larger C7-S1 SVA. Smaller spinal flexor/extensor volumes correlated with greater PI-LL mismatch (r = − 0.45 and − 0.51). Linear regression identified volume of biceps femoris as only predictor for PT (R2 = 0.34, p = 0.005) and Pfat of gluteus minimus as only predictor for SVA (R2 = 0.45, p = 0.001). Sagittally malaligned patients with larger PT (26.8° vs. 17.2°) had significantly smaller volume and larger Pfat of gluteus medius, gluteus minimus and biceps femoris, but similar values for gluteus maximus, the hip extensor. Conclusion This study is the first to quantify the relationship between degeneration of spino-femoral muscles and sagittal malalignment. This pathoanatomical study identifies the close relationship between gluteal, hamstring muscles and PT, SVA, which deepens our understanding of the underlying etiology that contributes to adult spinal deformity. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/19737 2020-01-01T00:00:00Z BAO, Hongda MOAL, Bertrand VIRA, Shaleen BRONSARD, Nicolas AMABILE, Célia ERRICO, Thomas SCHWAB, Frank SKALLI, Wafa DUBOUSSET, Jean LAFAGE, Virginie Objective To quantify muscle characteristics (volumes and fat infiltration) and identify their relationship to sagittal malalignment and compensatory mechanism recruitment. Methods Female adult spinal deformity patients underwent T1-weighted MRI with a 2-point Dixon protocol from the proximal tibia up to the T12 vertebra. 3D reconstructions of 17 muscles, including extensors and flexors of spine, hip and knee, were obtained. Muscle volume standardized by bone volume and percentage of fat infiltration (Pfat) were calculated. Correlations and regressions were performed. Results A total of 22 patients were included. Significant correlations were observed between sagittal alignment and muscle parameters. Fat infiltration of the hip and knee flexors and extensors correlated with larger C7-S1 SVA. Smaller spinal flexor/extensor volumes correlated with greater PI-LL mismatch (r = − 0.45 and − 0.51). Linear regression identified volume of biceps femoris as only predictor for PT (R2 = 0.34, p = 0.005) and Pfat of gluteus minimus as only predictor for SVA (R2 = 0.45, p = 0.001). Sagittally malaligned patients with larger PT (26.8° vs. 17.2°) had significantly smaller volume and larger Pfat of gluteus medius, gluteus minimus and biceps femoris, but similar values for gluteus maximus, the hip extensor. Conclusion This study is the first to quantify the relationship between degeneration of spino-femoral muscles and sagittal malalignment. This pathoanatomical study identifies the close relationship between gluteal, hamstring muscles and PT, SVA, which deepens our understanding of the underlying etiology that contributes to adult spinal deformity.