https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sun, 07 Jun 2026 13:29:38 GMT 2026-06-07T13:29:38Z http://hdl.handle.net/10985/15778 3D reconstruction of adolescent scoliotic trunk shape from biplanar X-rays: a feasibility study ROBICHON, Léopold; PINTO, Eleonora; HERNANDEZ, Thibault; VIALLE, Raphaël; SKALLI, Wafa; GAJNY, Laurent Adolescent idiopathic scoliosis (AIS) is a 3D deformity of the spine detectable by trunk asymmetry. As a decision-aid tool, a body scanner can help assessing non-invasively the external shape of the trunk. However if AIS is diagnosed, additional personalized 3D reconstructions of the spine, rib cage and pelvis are useful to have a complete understanding of the pathology and plan a treatment. For instance, both internal and external geometry are required for computer-aided brace design. Since a body scanner cannot currently guarantee reliable bones reconstruction, low-dose biplanar X-rays (BXR) is a relevant alternative. Indeed, it enables to compute reliable reconstructions of bony structures using validated methods daily used in clinical routine. More recently, 3D body shape reconstruction of asymptomatic subjects from BXR was also proved to be feasible with good accuracy. In order to prevent young scoliotic subjects from multiple examinations, we investigated the feasibility of trunk shape reconstruction from BXR. The proposed method relies on the 3D reconstructions of the spine, rib cage and pelvis priory performed and 10 radio-opaque markers placed on the subject on which we fit a statistical shape model (SSM). This model was built on a training set of 50 asymptomatic and 15 scoliotic female subjects for whom spine, rib cage, pelvis and trunk shape were reconstructed. The trunk shape reconstructions were assessed using the above mentioned method of body shape reconstruction. For the training on scoliotic subjects, this solution was corrected by 100 radio-opaque markers placed on the subjects and detected on the X-rays. During testing, after regression using the SSM, the trunk shape is registered automatically on apparent radiographic contours. Finally, few manual adjustments can be performed. This method has been evaluated on the 15 scoliotic subjects using a leave-one-out procedure. Signed marker-to-surface errors were computed on several trunk regions. The bias was everywhere lower than 0.7mm in absolute value and the standard deviation lower than 6mm. These results are promising and could be improved with a larger database. Thus, this study is a first step toward computer-aided brace design with a single examination. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/15778 2020-01-01T00:00:00Z ROBICHON, Léopold PINTO, Eleonora HERNANDEZ, Thibault VIALLE, Raphaël SKALLI, Wafa GAJNY, Laurent Adolescent idiopathic scoliosis (AIS) is a 3D deformity of the spine detectable by trunk asymmetry. As a decision-aid tool, a body scanner can help assessing non-invasively the external shape of the trunk. However if AIS is diagnosed, additional personalized 3D reconstructions of the spine, rib cage and pelvis are useful to have a complete understanding of the pathology and plan a treatment. For instance, both internal and external geometry are required for computer-aided brace design. Since a body scanner cannot currently guarantee reliable bones reconstruction, low-dose biplanar X-rays (BXR) is a relevant alternative. Indeed, it enables to compute reliable reconstructions of bony structures using validated methods daily used in clinical routine. More recently, 3D body shape reconstruction of asymptomatic subjects from BXR was also proved to be feasible with good accuracy. In order to prevent young scoliotic subjects from multiple examinations, we investigated the feasibility of trunk shape reconstruction from BXR. The proposed method relies on the 3D reconstructions of the spine, rib cage and pelvis priory performed and 10 radio-opaque markers placed on the subject on which we fit a statistical shape model (SSM). This model was built on a training set of 50 asymptomatic and 15 scoliotic female subjects for whom spine, rib cage, pelvis and trunk shape were reconstructed. The trunk shape reconstructions were assessed using the above mentioned method of body shape reconstruction. For the training on scoliotic subjects, this solution was corrected by 100 radio-opaque markers placed on the subjects and detected on the X-rays. During testing, after regression using the SSM, the trunk shape is registered automatically on apparent radiographic contours. Finally, few manual adjustments can be performed. This method has been evaluated on the 15 scoliotic subjects using a leave-one-out procedure. Signed marker-to-surface errors were computed on several trunk regions. The bias was everywhere lower than 0.7mm in absolute value and the standard deviation lower than 6mm. These results are promising and could be improved with a larger database. Thus, this study is a first step toward computer-aided brace design with a single examination. http://hdl.handle.net/10985/14979 Quasi-automatic early detection of progressive idiopathic scoliosis from biplanar radiography: a preliminary validation COURTOIS, Isabelle; EBERMEYER, Eric; ABELIN-GENEVOIS, Kariman; KIM, Youngwoo; LANGLAIS, Tristan; VIALLE, Raphaël; ASSI, Ayman; GHANEM, Ismat; DUBOUSSET, Jean; SKALLI, Wafa; GAJNY, Laurent; VERGARI, Claudio Purpose To validate the predictive power and reliability of a novel quasi-automatic method to calculate the severity index of adolescent idiopathic scoliosis (AIS). Methods Fifty-five AIS patients were prospectively included (Age: 10-15, Cobb: 16° ± 4°). Patients underwent low-dose biplanar x-rays and a novel fast method for 3D reconstruction of the spine was performed. They were followed until skeletal maturity (stable patients) or brace prescription (progressive patients). The severity index was calculated at the first exam, based on 3D parameters of the scoliotic curve, and it was compared with the patient’s final outcome (progressive or stable). Three operators have repeated the 3D reconstruction twice for a subset of 30 patients to assess reproducibility (through Cohen’s kappa and intraclass correlation coefficient). Results 85% of the patients were correctly classified as stable or progressive by the severity index, with a sensitivity of 92% and specificity of 74%. Substantial intra-operator agreement and good inter-operator agreement were observed, with 80% of the progressive patients correctly detected at the first exam. The novel severity index assessment took less than 4 minutes of operator time. Conclusions The fast and semi-automatic method for 3D reconstruction developed in this work allowed for a fast and reliable calculation of the severity index. The method is fast and user friendly. Once extensively validated, this severity index could allow very early initiation of conservative treatment for progressive patients, thus increasing treatment efficacy and therefore reducing the need for corrective surgery. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/14979 2019-01-01T00:00:00Z COURTOIS, Isabelle EBERMEYER, Eric ABELIN-GENEVOIS, Kariman KIM, Youngwoo LANGLAIS, Tristan VIALLE, Raphaël ASSI, Ayman GHANEM, Ismat DUBOUSSET, Jean SKALLI, Wafa GAJNY, Laurent VERGARI, Claudio Purpose To validate the predictive power and reliability of a novel quasi-automatic method to calculate the severity index of adolescent idiopathic scoliosis (AIS). Methods Fifty-five AIS patients were prospectively included (Age: 10-15, Cobb: 16° ± 4°). Patients underwent low-dose biplanar x-rays and a novel fast method for 3D reconstruction of the spine was performed. They were followed until skeletal maturity (stable patients) or brace prescription (progressive patients). The severity index was calculated at the first exam, based on 3D parameters of the scoliotic curve, and it was compared with the patient’s final outcome (progressive or stable). Three operators have repeated the 3D reconstruction twice for a subset of 30 patients to assess reproducibility (through Cohen’s kappa and intraclass correlation coefficient). Results 85% of the patients were correctly classified as stable or progressive by the severity index, with a sensitivity of 92% and specificity of 74%. Substantial intra-operator agreement and good inter-operator agreement were observed, with 80% of the progressive patients correctly detected at the first exam. The novel severity index assessment took less than 4 minutes of operator time. Conclusions The fast and semi-automatic method for 3D reconstruction developed in this work allowed for a fast and reliable calculation of the severity index. The method is fast and user friendly. Once extensively validated, this severity index could allow very early initiation of conservative treatment for progressive patients, thus increasing treatment efficacy and therefore reducing the need for corrective surgery. http://hdl.handle.net/10985/14977 Biplanar stereoradiography predicts pulmonary function tests in adolescent idiopathic scoliosis: a cross-sectional study BOULOUSSA, Houssam; HAEN, Thomas-Xavier; SKALLI, Wafa; VIALLE, Raphaël; VERGARI, Claudio Purpose Various spinal and rib cage parameters measured from complex examinations were found to be correlated with preoperative pulmonary function tests (PFT). The aim was to investigate the relationship between preoperative rib cage parameters and PFT using biplanar stereoradiography in patients with severe adolescent idiopathic scoliosis. Methods Fifty-four patients, 45 girls and nine boys, aged 13.8 ± 1.2 years, with Lenke 1 or 2 thoracic scoliosis (> 50°) requiring surgical correction were prospectively included. All patients underwent preoperative PFT and low-dose biplanar X-rays. The following data were collected: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio, residual volume, slow vital capacity (SVC), total lung capacity (TLC), rib cage volume (RCV), maximum rib hump, maximum width, mean thoracic index, spinal penetration index, apical vertebral rotation, main curve Cobb angle (MCCA), T4–T12 kyphosis. The primary outcome was the relationship between rib cage parameters and PFT. The secondary outcome was the relationship between rib cage parameters and spine parameters. Data were analyzed using Spearman’s rank test. A multivariable regression analysis was performed to compare PFTs and structural parameters. Significance was set at α = 0.05. Results The mean MCCA was 68.7° ± 16.7°. RCV was highly correlated with all pulmonary capacities: TLC (r = 0.76, p < 0.0001), SVC (r = 0.78, p < 0.0001) and FVC (r = 0.77, p < 0.0001). RCV had a low correlation with FEV1/FVC (r = − 0.34, p = 0.014). SPI was not correlated with any pulmonary parameters. Conclusion Rib cage volume measured by biplanar stereoradiography may represent a prediction tool for PFTs. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/14977 2019-01-01T00:00:00Z BOULOUSSA, Houssam HAEN, Thomas-Xavier SKALLI, Wafa VIALLE, Raphaël VERGARI, Claudio Purpose Various spinal and rib cage parameters measured from complex examinations were found to be correlated with preoperative pulmonary function tests (PFT). The aim was to investigate the relationship between preoperative rib cage parameters and PFT using biplanar stereoradiography in patients with severe adolescent idiopathic scoliosis. Methods Fifty-four patients, 45 girls and nine boys, aged 13.8 ± 1.2 years, with Lenke 1 or 2 thoracic scoliosis (> 50°) requiring surgical correction were prospectively included. All patients underwent preoperative PFT and low-dose biplanar X-rays. The following data were collected: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio, residual volume, slow vital capacity (SVC), total lung capacity (TLC), rib cage volume (RCV), maximum rib hump, maximum width, mean thoracic index, spinal penetration index, apical vertebral rotation, main curve Cobb angle (MCCA), T4–T12 kyphosis. The primary outcome was the relationship between rib cage parameters and PFT. The secondary outcome was the relationship between rib cage parameters and spine parameters. Data were analyzed using Spearman’s rank test. A multivariable regression analysis was performed to compare PFTs and structural parameters. Significance was set at α = 0.05. Results The mean MCCA was 68.7° ± 16.7°. RCV was highly correlated with all pulmonary capacities: TLC (r = 0.76, p < 0.0001), SVC (r = 0.78, p < 0.0001) and FVC (r = 0.77, p < 0.0001). RCV had a low correlation with FEV1/FVC (r = − 0.34, p = 0.014). SPI was not correlated with any pulmonary parameters. Conclusion Rib cage volume measured by biplanar stereoradiography may represent a prediction tool for PFTs. http://hdl.handle.net/10985/15615 A reduced micro-dose protocol for 3D reconstruction of the spine in children with scoliosis: results of a phantom-based and clinically validated study using stereo-radiography PEDERSEN, Peter H.; ALZAKRI, Abdulmajeed; VIALLE, Raphaël; SKALLI, Wafa; VERGARI, Claudio Purpose The aim of this study was to validate the reproducibility of 3D reconstructions of the spine using a new reduced micro-dose protocol. Methods First, semi-quantitative image analysis was performed using an anthropomorphic child phantom undergoing low-dose biplanar radiography. This analysis was used to establish a “lowest dose” allowing for acceptable visibility of spinal landmarks. Subsequently a group of 18 scoliotic children, 12 years of age or younger, underwent full-spine biplanar radiography with both micro-dose and the newly-defined reduced micro-dose. An intra- and inter-observer reliability study of 3D reconstructions of the spine was performed according to the International Organization for Standardization (ISO)-5725 standard, with three operators. Results The reduced micro-dose setting corresponded to a theoretical reduction of radiation dose exposure of approximately 58%. In vivo results showed acceptable intra- and inter-observer reliability (for instance 3.8° uncertainty on Cobb angle), comparable to previous studies on 3D spine reconstruction reliability and reproducibility based on stereo-radiography. Conclusion A new reduced micro-dose protocol offered reliable 3D reconstructions of the spine in patients with mild scoliosis. However, the quality of 3D reconstructions from both reduced micro-dose and micro-dose was inferior to standard-dose protocol on most parameters. Standard–dose protocol remains the option of choice for most accurate assessment and 3D reconstruction of the spine. Still, this new protocol offers a preliminary screening option and a follow-up tool for children with mild scoliosis yielding extremely low radiation and could replace micro-dose protocol for these patients. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/15615 2019-01-01T00:00:00Z PEDERSEN, Peter H. ALZAKRI, Abdulmajeed VIALLE, Raphaël SKALLI, Wafa VERGARI, Claudio Purpose The aim of this study was to validate the reproducibility of 3D reconstructions of the spine using a new reduced micro-dose protocol. Methods First, semi-quantitative image analysis was performed using an anthropomorphic child phantom undergoing low-dose biplanar radiography. This analysis was used to establish a “lowest dose” allowing for acceptable visibility of spinal landmarks. Subsequently a group of 18 scoliotic children, 12 years of age or younger, underwent full-spine biplanar radiography with both micro-dose and the newly-defined reduced micro-dose. An intra- and inter-observer reliability study of 3D reconstructions of the spine was performed according to the International Organization for Standardization (ISO)-5725 standard, with three operators. Results The reduced micro-dose setting corresponded to a theoretical reduction of radiation dose exposure of approximately 58%. In vivo results showed acceptable intra- and inter-observer reliability (for instance 3.8° uncertainty on Cobb angle), comparable to previous studies on 3D spine reconstruction reliability and reproducibility based on stereo-radiography. Conclusion A new reduced micro-dose protocol offered reliable 3D reconstructions of the spine in patients with mild scoliosis. However, the quality of 3D reconstructions from both reduced micro-dose and micro-dose was inferior to standard-dose protocol on most parameters. Standard–dose protocol remains the option of choice for most accurate assessment and 3D reconstruction of the spine. Still, this new protocol offers a preliminary screening option and a follow-up tool for children with mild scoliosis yielding extremely low radiation and could replace micro-dose protocol for these patients. http://hdl.handle.net/10985/19600 Biomechanical Evaluation of Intercostal Muscles in Healthy Children and Adolescent Idiopathic Scoliosis: A Preliminary Study PIETTON, Raphaël; DAVID, Mercedes; HISAUND, Alisa; LANGLAIS, Tristan; SKALLI, Wafa; VIALLE, Raphaël; VERGARI, Claudio Spine deformity during adolescent idiopathic scoliosis can induce a rib-cage deformity. This bone deformity can have direct consequences on the chest-wall muscles, including intercostal muscles, leading to respiratory impairments in individuals with severe cases. The aim of this study was to determine whether shear-wave elastography can be used to measure intercostal-muscle shear-wave speed (SWS) in healthy children and those with adolescent idiopathic scoliosis (AIS). Nineteen healthy participants and 16 with AIS took part. SWS measurements were taken by three operators, twice each. Average SWS was 2.3 ± 0.4 m/s, and inter-operator reproducibility was 0.2 m/s. SWS was significantly higher during apnea than in normal breathing (p < 0.01) in both groups. No significant difference was observed between groups in apnea or in normal breathing. Characterization of the intercostal muscles by ultrasound elastography is therefore feasible and reliable for children and adolescents with and without scoliosis. Fri, 01 Jan 2021 00:00:00 GMT http://hdl.handle.net/10985/19600 2021-01-01T00:00:00Z PIETTON, Raphaël DAVID, Mercedes HISAUND, Alisa LANGLAIS, Tristan SKALLI, Wafa VIALLE, Raphaël VERGARI, Claudio Spine deformity during adolescent idiopathic scoliosis can induce a rib-cage deformity. This bone deformity can have direct consequences on the chest-wall muscles, including intercostal muscles, leading to respiratory impairments in individuals with severe cases. The aim of this study was to determine whether shear-wave elastography can be used to measure intercostal-muscle shear-wave speed (SWS) in healthy children and those with adolescent idiopathic scoliosis (AIS). Nineteen healthy participants and 16 with AIS took part. SWS measurements were taken by three operators, twice each. Average SWS was 2.3 ± 0.4 m/s, and inter-operator reproducibility was 0.2 m/s. SWS was significantly higher during apnea than in normal breathing (p < 0.01) in both groups. No significant difference was observed between groups in apnea or in normal breathing. Characterization of the intercostal muscles by ultrasound elastography is therefore feasible and reliable for children and adolescents with and without scoliosis. http://hdl.handle.net/10985/11887 Experimental validation of a patient-specific model of orthotic action in adolescent idiopathic scoliosis COURTOIS, Isabelle; EBERMEYER, Eric; VIALLE, Raphaël; BOULOUSSA, Houssam; SKALLI, Wafa; VERGARI, Claudio Purpose Personalized modeling of brace action have potential in improving brace efficacy in adolescent idiopathic scoliosis (AIS). Model validation and simulation uncertainty are rarely addressed, limiting the clinical implementation of personalized models. We hypothesized that a thorough validation of a personalized finite element model (FEM) of brace action would highlight potential means of improving the model. Methods 42 AIS patients were included retrospectively and prospectively. Personalized FEMs of pelvis, spine and ribcage were built from stereoradiographies. Brace action was simulated through soft cylindrical pads acting on the ribcage and through displacements applied to key vertebrae. Simulation root mean squared errors (RMSEs) were calculated by comparison with the actual brace action (quantified through clinical indices, vertebral positions and orientations) observed in in-brace stereoradiographies. Results Simulation RMSEs of Cobb angle and vertebral apical axial rotation was lower than measurement uncertainty in 79% of the patients. Pooling all patients and clinical indices, 87 % of the indices had lower RMSEs than the measurement uncertainty. Conclusions In-depth analysis suggests that personalization of spinal functional units mechanical properties could improve the simulation’s accuracy, but the model gave good results, thus justifying further research on its clinical application. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/11887 2016-01-01T00:00:00Z COURTOIS, Isabelle EBERMEYER, Eric VIALLE, Raphaël BOULOUSSA, Houssam SKALLI, Wafa VERGARI, Claudio Purpose Personalized modeling of brace action have potential in improving brace efficacy in adolescent idiopathic scoliosis (AIS). Model validation and simulation uncertainty are rarely addressed, limiting the clinical implementation of personalized models. We hypothesized that a thorough validation of a personalized finite element model (FEM) of brace action would highlight potential means of improving the model. Methods 42 AIS patients were included retrospectively and prospectively. Personalized FEMs of pelvis, spine and ribcage were built from stereoradiographies. Brace action was simulated through soft cylindrical pads acting on the ribcage and through displacements applied to key vertebrae. Simulation root mean squared errors (RMSEs) were calculated by comparison with the actual brace action (quantified through clinical indices, vertebral positions and orientations) observed in in-brace stereoradiographies. Results Simulation RMSEs of Cobb angle and vertebral apical axial rotation was lower than measurement uncertainty in 79% of the patients. Pooling all patients and clinical indices, 87 % of the indices had lower RMSEs than the measurement uncertainty. Conclusions In-depth analysis suggests that personalization of spinal functional units mechanical properties could improve the simulation’s accuracy, but the model gave good results, thus justifying further research on its clinical application. http://hdl.handle.net/10985/18368 Shear wave elastography of lumbar annulus fibrosus in adolescent idiopathic scoliosis before and after surgical intervention CHANTEUX, Lucas; PIETTON, Raphaël; LANGLAIS, Tristan; VIALLE, Raphaël; SKALLI, Wafa; VERGARI, Claudio Abstract Objectives To determine lumbar intervertebral disc properties with shear wave elastography in adolescent idiopathic scoliotic (AIS) patients before and after surgery, and compare them with asymptomatic controls. Methods Twenty-five severe AIS patients with an indication for fusion surgery (15 ± 1.5 years old, the Cobb angle ranging between 40 and 93°) and fifty-nine asymptomatic adolescents (13 ± 2 years old) were included prospectively. Shear wave speed (SWS) was measured in the annulus fibrosus of L3-L4, L4-L5, and L5-S1 discs of each subject. In AIS patients, measurements took place before surgery, and 3 months (N = 13) or 1 year after (N = 12). Results No difference was observed between disc levels in any group. When pooling disc levels, SWS was significantly higher in preop AIS patients (4.0 ± 0.5 m/s) than in asymptomatic subjects (3.1 ± 0.5 m/s, p < 0.0001). SWS decreased 3 months postop (3.5 ± 0.3 m/s), and it decreased further towards normal values 1 year after (3.3 ± 0.4 m/s). SWS in preop AIS patients tended to decrease with the Cobb angle (Spearman’s rho = − 0.4, p = 0.05). Conclusion Shear wave elastography measurements showed that discs in AIS patients were altered relative to asymptomatic ones, and this alteration tended to normalize 1 year post fusion surgery. Further studies should aim at determining if bracing of mild scoliosis has an effect on disc properties. Key Points • Shear wave elastography shows alteration of annulus fibrosus in adolescent idiopathic scoliosis. • Disc elastography tends to normalize 1 year after surgery. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/18368 2020-01-01T00:00:00Z CHANTEUX, Lucas PIETTON, Raphaël LANGLAIS, Tristan VIALLE, Raphaël SKALLI, Wafa VERGARI, Claudio Abstract Objectives To determine lumbar intervertebral disc properties with shear wave elastography in adolescent idiopathic scoliotic (AIS) patients before and after surgery, and compare them with asymptomatic controls. Methods Twenty-five severe AIS patients with an indication for fusion surgery (15 ± 1.5 years old, the Cobb angle ranging between 40 and 93°) and fifty-nine asymptomatic adolescents (13 ± 2 years old) were included prospectively. Shear wave speed (SWS) was measured in the annulus fibrosus of L3-L4, L4-L5, and L5-S1 discs of each subject. In AIS patients, measurements took place before surgery, and 3 months (N = 13) or 1 year after (N = 12). Results No difference was observed between disc levels in any group. When pooling disc levels, SWS was significantly higher in preop AIS patients (4.0 ± 0.5 m/s) than in asymptomatic subjects (3.1 ± 0.5 m/s, p < 0.0001). SWS decreased 3 months postop (3.5 ± 0.3 m/s), and it decreased further towards normal values 1 year after (3.3 ± 0.4 m/s). SWS in preop AIS patients tended to decrease with the Cobb angle (Spearman’s rho = − 0.4, p = 0.05). Conclusion Shear wave elastography measurements showed that discs in AIS patients were altered relative to asymptomatic ones, and this alteration tended to normalize 1 year post fusion surgery. Further studies should aim at determining if bracing of mild scoliosis has an effect on disc properties. Key Points • Shear wave elastography shows alteration of annulus fibrosus in adolescent idiopathic scoliosis. • Disc elastography tends to normalize 1 year after surgery. http://hdl.handle.net/10985/21598 Changes in quantitative elastography assessment of the adjacent lumbar disc after segmental fixation of the spine: a case description of a burst fracture of L4 PIETTON, Raphaël; VIALLE, Raphaël; LAURENT, Romain; SKALLI, Wafa; VERGARI, Claudio; LANGLAIS, Tristan Vertebral burst fractures are usually due to traumatic high-energy distraction of the vertebra. They often require pedicle screw fixation to stabilize the spine during the healing process but once the fusion of the fractured vertebra has occurred, the posterior fixation can be removed or shortened to restore part of the spinal mobility. The importance of sparing fusion levels to ensure optimal functional results has been demonstrated. In surgical planning, the rule is therefore to ensure the osteosynthesis stability while limiting the number of levels included. Immobilization or fixation of a vertebral segment may be responsible for degeneration of the intervertebral disc and in case of surgical treatment the adjacent disc. Therefore, we can ask whether removal of a vertebral fixation could decrease the stress on adjacent segments. Ultrasound shearwave elastography is a new innovative and non-invasive technique allowing evaluation of soft tissue’s elastic modulus through the measurement of shear wave speed (SWS). This non-invasive imaging method has shown its added value in breast or in liver oncology and, more recently, in musculoskeletal pathologies assessment. In particular, Langlais et al. found that SWS measured in annulus fibrosus was significantly higher in progressive adolescent idiopathic scoliosis than in asymptomatic population, which is associated with a stiffer tissue. The same authors defined a corridor of normality (2.3–3.7 m/s) for the asymptomatic population and observed that annulus SWS tended to normalize 1 year after fusion surgery in severe adolescent idiopathic scoliosis. The aim of this case was to analyze the effect of removing the posterior fixation in a case of burst fracture on the mechanical properties of the bridged and adjacent intervertebral discs. Sat, 01 Jan 2022 00:00:00 GMT http://hdl.handle.net/10985/21598 2022-01-01T00:00:00Z PIETTON, Raphaël VIALLE, Raphaël LAURENT, Romain SKALLI, Wafa VERGARI, Claudio LANGLAIS, Tristan Vertebral burst fractures are usually due to traumatic high-energy distraction of the vertebra. They often require pedicle screw fixation to stabilize the spine during the healing process but once the fusion of the fractured vertebra has occurred, the posterior fixation can be removed or shortened to restore part of the spinal mobility. The importance of sparing fusion levels to ensure optimal functional results has been demonstrated. In surgical planning, the rule is therefore to ensure the osteosynthesis stability while limiting the number of levels included. Immobilization or fixation of a vertebral segment may be responsible for degeneration of the intervertebral disc and in case of surgical treatment the adjacent disc. Therefore, we can ask whether removal of a vertebral fixation could decrease the stress on adjacent segments. Ultrasound shearwave elastography is a new innovative and non-invasive technique allowing evaluation of soft tissue’s elastic modulus through the measurement of shear wave speed (SWS). This non-invasive imaging method has shown its added value in breast or in liver oncology and, more recently, in musculoskeletal pathologies assessment. In particular, Langlais et al. found that SWS measured in annulus fibrosus was significantly higher in progressive adolescent idiopathic scoliosis than in asymptomatic population, which is associated with a stiffer tissue. The same authors defined a corridor of normality (2.3–3.7 m/s) for the asymptomatic population and observed that annulus SWS tended to normalize 1 year after fusion surgery in severe adolescent idiopathic scoliosis. The aim of this case was to analyze the effect of removing the posterior fixation in a case of burst fracture on the mechanical properties of the bridged and adjacent intervertebral discs. http://hdl.handle.net/10985/21437 3D quasi-automatic spine length assessment using low dose biplanar radiography after surgical correction in thoracic idiopathic scoliosis LANGLAIS, T; VERGARI, Claudio; XAVIER, F; AL HAWSAWI, M; GAJNY, Laurent; VIALLE, Raphaël; SKALLI, Wafa; PIETTON, Raphaël Background: As a leading cause of disability with a high societal and economic cost, it is crucial to better understand risk factors of neck pain and surgical complications. Getting subject-specific external loading is essential for quantifying muscle forces and joint loads but it requires exertion trials and load cells which are uncommon in clinical settings. Methods: This paper presents a method to compute the gravitational loading at four levels of the cervical spine (C3C4, C4C5, C5C6, C6C7) in neutral standing position from biplanar radiographs exclusively. The resulting load was decomposed in local disc frames and its components were used to compare different populations: 118 asymptomatic subjects and 46 patients before and after surgery (anterior cervical discectomy and fusion or total disc replacement). Comparisons were performed at C6C7 and the upper level adjacent to surgery. Findings: Significant changes in gravitational loading were observed with age in healthy subjects as well as in patients after surgery and have been associated with changes in posture. Interpretation: This approach quantifies the influence of postural changes on gravitational loading on the cervical spine. It represents a simple way to obtain necessary input for muscle force quantification models in clinical routine and to use them for patient evaluation. The study of the subsequent subject-specific spinal loading could help further the understanding of cervical spine biomechanics, degeneration mechanisms and complications following surgery. Sat, 01 Jan 2022 00:00:00 GMT http://hdl.handle.net/10985/21437 2022-01-01T00:00:00Z LANGLAIS, T VERGARI, Claudio XAVIER, F AL HAWSAWI, M GAJNY, Laurent VIALLE, Raphaël SKALLI, Wafa PIETTON, Raphaël Background: As a leading cause of disability with a high societal and economic cost, it is crucial to better understand risk factors of neck pain and surgical complications. Getting subject-specific external loading is essential for quantifying muscle forces and joint loads but it requires exertion trials and load cells which are uncommon in clinical settings. Methods: This paper presents a method to compute the gravitational loading at four levels of the cervical spine (C3C4, C4C5, C5C6, C6C7) in neutral standing position from biplanar radiographs exclusively. The resulting load was decomposed in local disc frames and its components were used to compare different populations: 118 asymptomatic subjects and 46 patients before and after surgery (anterior cervical discectomy and fusion or total disc replacement). Comparisons were performed at C6C7 and the upper level adjacent to surgery. Findings: Significant changes in gravitational loading were observed with age in healthy subjects as well as in patients after surgery and have been associated with changes in posture. Interpretation: This approach quantifies the influence of postural changes on gravitational loading on the cervical spine. It represents a simple way to obtain necessary input for muscle force quantification models in clinical routine and to use them for patient evaluation. The study of the subsequent subject-specific spinal loading could help further the understanding of cervical spine biomechanics, degeneration mechanisms and complications following surgery. http://hdl.handle.net/10985/19958 EOS 3D Imaging: assessing the impact of brace treatment in adolescent idiopathic scoliosis COURVOISIER, Aurélien; VIALLE, Raphaël; SKALLI, Wafa One of the major revolutions in the field of adolescent idiopathic scoliosis (AIS) during the past 10 years is the development of 3D imaging devices in standing position, such as EOS (EOS Imaging). 3D vision of the spine is new; we need to be humble and learn how it may help in the management of AIS. But we now have access to the transverse plane deformity. We do not know how to heal idiopathic scoliosis. Thus, the main issue in the field of AIS management is to avoid progression of mild scoliosis. Brace treatment is the main treatment option for mild scoliotic patients during growth. However, the efficacy of brace treatment is not consensual. We have demonstrated through a 3D analysis of brace treatment that some braces are truly efficient, some are not and others worsen the spinal deformity. Therefore, we have to anticipate the effect of a brace on a specific patient. With 3D analysis we are now able to evaluate if a brace really improves the spinal shape in the 3 dimensions or not. Moreover, we have the patient 3D geometry (spine and rib cage) and we are able to collect objective clinical data that could help achieve relevant parametric finite element models. These models could help in the prediction of brace effect but they need to be validated with clinical data. We see a close future where we will all have the 3D trunk shape of our patients on our screens along with all computed angles we need and then an instant prediction for the best-fit brace geometry for our patient. Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10985/19958 2014-01-01T00:00:00Z COURVOISIER, Aurélien VIALLE, Raphaël SKALLI, Wafa One of the major revolutions in the field of adolescent idiopathic scoliosis (AIS) during the past 10 years is the development of 3D imaging devices in standing position, such as EOS (EOS Imaging). 3D vision of the spine is new; we need to be humble and learn how it may help in the management of AIS. But we now have access to the transverse plane deformity. We do not know how to heal idiopathic scoliosis. Thus, the main issue in the field of AIS management is to avoid progression of mild scoliosis. Brace treatment is the main treatment option for mild scoliotic patients during growth. However, the efficacy of brace treatment is not consensual. We have demonstrated through a 3D analysis of brace treatment that some braces are truly efficient, some are not and others worsen the spinal deformity. Therefore, we have to anticipate the effect of a brace on a specific patient. With 3D analysis we are now able to evaluate if a brace really improves the spinal shape in the 3 dimensions or not. Moreover, we have the patient 3D geometry (spine and rib cage) and we are able to collect objective clinical data that could help achieve relevant parametric finite element models. These models could help in the prediction of brace effect but they need to be validated with clinical data. We see a close future where we will all have the 3D trunk shape of our patients on our screens along with all computed angles we need and then an instant prediction for the best-fit brace geometry for our patient.