Vincent Pomero | Aix-Marseille University (original) (raw)
Papers by Vincent Pomero
Computer Methods in Biomechanics and Biomedical Engineering, 2015
The aim of this study was to evaluate whether clinical parameters are sufficient using, a multili... more The aim of this study was to evaluate whether clinical parameters are sufficient using, a multilinear regression model, to reproduce the sagittal plane joint angles (hip, knee, and ankle) in cerebral palsy gait. A total of 154 patients were included. The two legs were considered (308 observations). Thirty-six clinical parameters were used as regressors (range of motion, muscle strength, and spasticity of the lower). From the clinical gait analysis, the joint angles of the sagittal plane were selected. Results showed that clinical parameter does not provide sufficient information to recover joint angles and/or that the multilinear regression model is not an appropriate solution.
Traducción: F. Colell (GBMOIM) Definición La cavitación es la formación de bolsas y burbujas de v... more Traducción: F. Colell (GBMOIM) Definición La cavitación es la formación de bolsas y burbujas de vapor en un medio líquido inicialmente homogéneo. Se puede definir mecánicamente como la ruptura del medio de líquido contínuo bajo el efecto de tensiones excesivas. Con este último término se sobreentiende la noción de umbral a partir del cual no se puede asegurar la cohesión del líquido. Veremos que este concepto de umbral está determinado por la presión que reina en el seno de este líquido. La cavitación puede producirse en el caso de un líquido en reposo o en la circulación del líquido. Un ejemplo simple en el ámbito médico, que todos podemos observar, es el llenado de una jeringa por aspiración; si la aspiración es demasiado intensa, vemos aparecer una burbuja de gas en la jeringa. Fenómenos físicos Si tomamos el ejemplo del agua y observamos la evolución de su estado en función de la temperatura, se constatan los hechos siguientes. A presión atmosférica, el agua en forma de hielo al...
L'objectif de ce travail est d'élaborer un modèle d'évaluation musculaire adapté à l&... more L'objectif de ce travail est d'élaborer un modèle d'évaluation musculaire adapté à l'étude de patients, afin de déterminer les relations existantes entre la musculature du tronc, un trouble postural et les surcharges rachidiennes. Dans cet objectif, un premier chapitre s'attache à présenter le problème (anatomie fonctionnelle et formulation mécanique), puis une revue de littérature est proposée afin d'identifier les différents modèles et protocoles d'acquisition des données proposés par différents chercheurs. Dans le chapitre III, un modèle de régulation musculaire est proposé, fondé sur l'hypothèse que le système musculaire est un système de régulation permettant de maintenir les efforts rachidiens en deçà de seuils mécaniquement admissibles. Ce modèle, par plan de coupe au niveau de la liaison intervertébrale considérée, est comparé à d'autres de la littérature et se révèle pertinent, notamment du fait de sa capacité à proposer des configuration...
European Spine Journal, 2009
Many believe that the fetus spine had only one curvature from cranial to caudal which is a global... more Many believe that the fetus spine had only one curvature from cranial to caudal which is a global kyphosis and that the lumbosacral lordosis appears with the erect posture. They agree that the sacrum of Homo sapiens is not positioned posteriorly at birth and that it is during the first few years that the sacrum, in humans, moves dorsally in relation with the progressive acquisition of erect posture and the ontogeny of bipedal locomotion. Nevertheless, there is no biometric study assessing these parameters in vivo in utero during the fetal life. Cross-sectional biometric study of the lumbosacral junction of the spine in in utero fetuses was to document the presence of a lumbosacral lordosis in the fetal population in utero long before standing and walking and its change during growth. Fortyfive MRIs (magnetic resonance imaging) of fetuses aged of 23-40 weeks of gestation were analyzed. The measurements were performed on computerized MRI DICOM images using a professional software to calculate the curvature and radius of the lumbosacral junction. The presence or absence of visual lumbosacral lordosis was noted for each case. Correlation tests were performed in order to disclose a correlation between the gestational age and the curvature calculated. A test was considered significant for P \ 0.01. There were 14 males, 17 females and 14 undetermined. All the curves (100%) showed mathematically the presence of a lordosis in the lumbosacral region. The visual lumbosacral lordosis was present in 60% of cases. The measurement of the lumbosacral curvature varies between -0.133 and -0.033 mm -1 and a mean of -0.054 mm -1 with a corresponding radius ranging from -7 to -303 mm with a mean of -18.7 mm. The statistical analysis showed no correlation between the gestational age and the lumbosacral curvature (R 2 = 0.11). The hypothesis of increased lumbosacral lordosis with gestational age is rejected. It is difficult to accurately determine the role played separately by genetics and by erect posture. A visual lumbosacral lordosis was noted in 60% of cases with mean radius of -18.6691 mm. This lordosis was not correlated statistically to gestational age which means that it is not related to growth and might be genetically determined. Mechanical factors may play a major role in the determination of the shape of the growing pelvis. One can ask if the pelvis morphology is genetically determined or if it is mechanically determined under muscular and ligamentous stresses. This study shows that the sacrum of human fetuses is oriented posteriorly mathematically in 100% of cases, and in 60% of cases based on the morphologic appearance of the lumbosacral junction. So beside the effect of progressive acquisition of erect posture and bipedalism in determining the formation of lumbosacral angle, we believe that genetics play an important role in the formation of the lumbosacral angle.
World journal of orthopedics, Jan 18, 2015
To describe initial results and experimental error measurement of a protocol analyzing Human post... more To describe initial results and experimental error measurement of a protocol analyzing Human posture through sagittal intersegmental moments. Postural analysis has been recently improved by development of three-dimensional radiographic imaging systems. However, in various situations such as global sagittal anterior malalignment interpretation of radiographs may not represent the real alignment of the subject. The aim of this study was to present initial results of a 3D biomechanical protocol. This protocol is obtained in a free standing position and characterizes postural balance by measurement of sagittal intersegmental net moments. After elaboration of a specific marker-set, 4 successive recordings were done on two volunteers by three different operators during three sessions in order to evaluate the experimental error measurement. A supplementary acquisition in a "radiographic" posture was also obtained. Once the data acquired, joint center, length, anatomical frame and...
Revue de Chirurgie Orthopédique et Réparatrice de l'Appareil Moteur, 2007
![Research paper thumbnail of [Thoracic scoliosis: exothoracic and endothoracic deformations and the spinal penetration index]](https://attachments.academia-assets.com/42192810/thumbnails/1.jpg)
](Revue de Chirurgie Orthopédique et Réparatrice de l Appareil Moteur
We reviewed retrospectively our patients with thoracic lordoscoliosis and conducted a conceptual ... more We reviewed retrospectively our patients with thoracic lordoscoliosis and conducted a conceptual analysis of the patients with airway compression and atelectasia due to anterior protrusion of the vertebral bodies in order to describe the pathological conditions involved and the management methods used. Our goal was to develop a new concept for quantifying thoracic deformation. The individual cases discussed here have been reported earlier, but this is the first series analysis to date. Eighteen patients, aged 7.3 to 18 years, with thoracic lordoscoliosis due to a variety of causes, mostly neuromuscular disorders (12 cases), are described. Most patients were treated by anterior subtotal periosteal resection of the vertebral body followed by posterior instrumentation and arthrodesis. Atelectasia disappeared with a normalization of blood gases but the effect was variable on vital capacity. The analysis of the CT studies led to the concept of spinal deformity as an endothoracic deformat...
Studies in health technology and informatics
The objectives of the study are to describe and use a muscular model to compare spinal loads and ... more The objectives of the study are to describe and use a muscular model to compare spinal loads and muscles recruitments between an unbalanced subject (patient) and a normal volunteer. Data collection was performed and imputed into the muscular model: from sagittal X-rays, together with plantar foot pressure measurements, external loads for the L3/L4 level were calculated. Using MRI of the thoraco-lumbar region and muscular testing, a personalized muscular model was constructed. The main results are as follow: external loads for the unbalanced subject were higher because of the postural default, especially for flexion moment. Running the model, simulations showed a higher erector spinae group activation for the patient. This induced a significant difference in joint compression. Setting the maximum admissible stress of the extensor muscles of the patient to an equivalent level as the one found for the volunteer to maintain the posture, a second simulation was performed. Joint compressi...
Revue de Chirurgie Orthopédique et Réparatrice de l'Appareil Moteur, 2004
Revue de Chirurgie Orthopédique et Traumatologique, 2015
Revue de Chirurgie Orthopédique et Réparatrice de l'Appareil Moteur, 2007
ABSTRACT Introduction L’association de moelle osseuse à la greffe lors des arthrodèses lombaires ... more ABSTRACT Introduction L’association de moelle osseuse à la greffe lors des arthrodèses lombaires est une technique largement utilisée. La moelle apporte des cellules souches et des facteurs de croissance contenus dans les plaquettes, favorables à la repousse osseuse. L’adjonction de moelle osseuse sous sa forme concentrée pourrait en théorie créer des conditions encore plus favorables et majorer la repousse osseuse. Le but de cette étude a été de comparer quantitativement sur des images scannographiques la repousse osseuse entre les sites d’arthrodèse ayant reçu de la moelle osseuse concentrée et ceux ayant reçu de la moelle osseuse non concentrée. Méthode Il s’agissait d’une étude prospective sur 15 patients présentant des lombo-sciatalgies chroniques sur rachis dégénératif. En peropératoire, une fraction de la ponction de moelle osseuse a été concentrée par centrifugation afin de récupérer un concentré de cellules mononucléés (contenant les cellules souches) et de plaquettes. Un coté a reçu ce concentré, l’os de décortication et des céramiques. L’autre coté a reçu le même greffon avec de la moelle osseuse non concentrée. Une analyse quantitative a été réalisée, à l’aide d’un logiciel de mesure semi-automatisé, sur des images scannographiques, permettant de déterminer le volume d’os cortical dans le greffon en postopératoire immédiat et à 3 mois. Les concentrations en cellules souches et en plaquettes dans chaque échantillon de moelle injectée ont été déterminées pour chaque patient par comptage, culture et phénotypage. Résultats L’étude biologique montre un taux de concentration moyen de 6 fois pour les cellules mononucléées et de 3,3 fois pour les plaquettes. La comparaison du volume en os cortical de chaque coté en postopératoire et à 3 mois n’a pas mis en évidence de différence significative. Discussion et conclusion Malgré la concentration effectuée, quantifiée biologiquement, il n’a pas été mis en évidence de majoration de la repousse osseuse en ajoutant de la moelle osseuse concentrée. Cependant, la quantité de cellules souches étant très faible dans la moelle osseuse, il se peut qu’il faille une concentration supérieure à celle que nous avons obtenue pour faire apparaître une différence. De plus, Le problème principal rencontré a été une concentration peropératoire aléatoire de la moelle osseuse. Enfin, la technique de reconstruction 3D du greffon et son analyse se sont montrées efficaces car le calcul du volume du greffon postopératoire a été sensiblement le même chez tous les patients.
Revue de Chirurgie Orthopédique et Traumatologique, 2015
Annals of physical and rehabilitation medicine, 2014
In hemiplegic children the appearance of equinovarus is correlated with premature electromyograph... more In hemiplegic children the appearance of equinovarus is correlated with premature electromyography (EMG) activity of the gastrocnemius medialis (GM) prior to initial contact. The goal was to analyze the onset of EMG activation in the GM and, more particularly, the peroneus longus (PL) in cases of equinovarus: is PL activity likewise premature? As 15 hemiplegic children (age 5 years±1.5) with equinovarus walked, their PL and GM EMG activity was being recorded. The latter was normalized in terms of gait cycle percentage (0-100%) and detected through semi-automatic selection with activation threshold set at 20μV. A paired t-test compared activation onset of the PL versus the GM muscles. As regards the healthy limb, activity onset of the GM (+14.55%) and the PL (+19.2%) muscles occurred only during the ST. In cases of equinovarus, activation of the GM (-5.2%) and the PL (-6.1%) occurred during the SW and was premature. For each muscle, comparison between the healthy and the hemiplegic s...
Journal of Spinal Disorders
Computer Methods in Biomechanics and Biomedical Engineering, 2015
The aim of this study was to evaluate whether clinical parameters are sufficient using, a multili... more The aim of this study was to evaluate whether clinical parameters are sufficient using, a multilinear regression model, to reproduce the sagittal plane joint angles (hip, knee, and ankle) in cerebral palsy gait. A total of 154 patients were included. The two legs were considered (308 observations). Thirty-six clinical parameters were used as regressors (range of motion, muscle strength, and spasticity of the lower). From the clinical gait analysis, the joint angles of the sagittal plane were selected. Results showed that clinical parameter does not provide sufficient information to recover joint angles and/or that the multilinear regression model is not an appropriate solution.
Traducción: F. Colell (GBMOIM) Definición La cavitación es la formación de bolsas y burbujas de v... more Traducción: F. Colell (GBMOIM) Definición La cavitación es la formación de bolsas y burbujas de vapor en un medio líquido inicialmente homogéneo. Se puede definir mecánicamente como la ruptura del medio de líquido contínuo bajo el efecto de tensiones excesivas. Con este último término se sobreentiende la noción de umbral a partir del cual no se puede asegurar la cohesión del líquido. Veremos que este concepto de umbral está determinado por la presión que reina en el seno de este líquido. La cavitación puede producirse en el caso de un líquido en reposo o en la circulación del líquido. Un ejemplo simple en el ámbito médico, que todos podemos observar, es el llenado de una jeringa por aspiración; si la aspiración es demasiado intensa, vemos aparecer una burbuja de gas en la jeringa. Fenómenos físicos Si tomamos el ejemplo del agua y observamos la evolución de su estado en función de la temperatura, se constatan los hechos siguientes. A presión atmosférica, el agua en forma de hielo al...
L'objectif de ce travail est d'élaborer un modèle d'évaluation musculaire adapté à l&... more L'objectif de ce travail est d'élaborer un modèle d'évaluation musculaire adapté à l'étude de patients, afin de déterminer les relations existantes entre la musculature du tronc, un trouble postural et les surcharges rachidiennes. Dans cet objectif, un premier chapitre s'attache à présenter le problème (anatomie fonctionnelle et formulation mécanique), puis une revue de littérature est proposée afin d'identifier les différents modèles et protocoles d'acquisition des données proposés par différents chercheurs. Dans le chapitre III, un modèle de régulation musculaire est proposé, fondé sur l'hypothèse que le système musculaire est un système de régulation permettant de maintenir les efforts rachidiens en deçà de seuils mécaniquement admissibles. Ce modèle, par plan de coupe au niveau de la liaison intervertébrale considérée, est comparé à d'autres de la littérature et se révèle pertinent, notamment du fait de sa capacité à proposer des configuration...
European Spine Journal, 2009
Many believe that the fetus spine had only one curvature from cranial to caudal which is a global... more Many believe that the fetus spine had only one curvature from cranial to caudal which is a global kyphosis and that the lumbosacral lordosis appears with the erect posture. They agree that the sacrum of Homo sapiens is not positioned posteriorly at birth and that it is during the first few years that the sacrum, in humans, moves dorsally in relation with the progressive acquisition of erect posture and the ontogeny of bipedal locomotion. Nevertheless, there is no biometric study assessing these parameters in vivo in utero during the fetal life. Cross-sectional biometric study of the lumbosacral junction of the spine in in utero fetuses was to document the presence of a lumbosacral lordosis in the fetal population in utero long before standing and walking and its change during growth. Fortyfive MRIs (magnetic resonance imaging) of fetuses aged of 23-40 weeks of gestation were analyzed. The measurements were performed on computerized MRI DICOM images using a professional software to calculate the curvature and radius of the lumbosacral junction. The presence or absence of visual lumbosacral lordosis was noted for each case. Correlation tests were performed in order to disclose a correlation between the gestational age and the curvature calculated. A test was considered significant for P \ 0.01. There were 14 males, 17 females and 14 undetermined. All the curves (100%) showed mathematically the presence of a lordosis in the lumbosacral region. The visual lumbosacral lordosis was present in 60% of cases. The measurement of the lumbosacral curvature varies between -0.133 and -0.033 mm -1 and a mean of -0.054 mm -1 with a corresponding radius ranging from -7 to -303 mm with a mean of -18.7 mm. The statistical analysis showed no correlation between the gestational age and the lumbosacral curvature (R 2 = 0.11). The hypothesis of increased lumbosacral lordosis with gestational age is rejected. It is difficult to accurately determine the role played separately by genetics and by erect posture. A visual lumbosacral lordosis was noted in 60% of cases with mean radius of -18.6691 mm. This lordosis was not correlated statistically to gestational age which means that it is not related to growth and might be genetically determined. Mechanical factors may play a major role in the determination of the shape of the growing pelvis. One can ask if the pelvis morphology is genetically determined or if it is mechanically determined under muscular and ligamentous stresses. This study shows that the sacrum of human fetuses is oriented posteriorly mathematically in 100% of cases, and in 60% of cases based on the morphologic appearance of the lumbosacral junction. So beside the effect of progressive acquisition of erect posture and bipedalism in determining the formation of lumbosacral angle, we believe that genetics play an important role in the formation of the lumbosacral angle.
World journal of orthopedics, Jan 18, 2015
To describe initial results and experimental error measurement of a protocol analyzing Human post... more To describe initial results and experimental error measurement of a protocol analyzing Human posture through sagittal intersegmental moments. Postural analysis has been recently improved by development of three-dimensional radiographic imaging systems. However, in various situations such as global sagittal anterior malalignment interpretation of radiographs may not represent the real alignment of the subject. The aim of this study was to present initial results of a 3D biomechanical protocol. This protocol is obtained in a free standing position and characterizes postural balance by measurement of sagittal intersegmental net moments. After elaboration of a specific marker-set, 4 successive recordings were done on two volunteers by three different operators during three sessions in order to evaluate the experimental error measurement. A supplementary acquisition in a "radiographic" posture was also obtained. Once the data acquired, joint center, length, anatomical frame and...
Revue de Chirurgie Orthopédique et Réparatrice de l'Appareil Moteur, 2007
Revue de Chirurgie Orthopédique et Réparatrice de l Appareil Moteur
We reviewed retrospectively our patients with thoracic lordoscoliosis and conducted a conceptual ... more We reviewed retrospectively our patients with thoracic lordoscoliosis and conducted a conceptual analysis of the patients with airway compression and atelectasia due to anterior protrusion of the vertebral bodies in order to describe the pathological conditions involved and the management methods used. Our goal was to develop a new concept for quantifying thoracic deformation. The individual cases discussed here have been reported earlier, but this is the first series analysis to date. Eighteen patients, aged 7.3 to 18 years, with thoracic lordoscoliosis due to a variety of causes, mostly neuromuscular disorders (12 cases), are described. Most patients were treated by anterior subtotal periosteal resection of the vertebral body followed by posterior instrumentation and arthrodesis. Atelectasia disappeared with a normalization of blood gases but the effect was variable on vital capacity. The analysis of the CT studies led to the concept of spinal deformity as an endothoracic deformat...
Studies in health technology and informatics
The objectives of the study are to describe and use a muscular model to compare spinal loads and ... more The objectives of the study are to describe and use a muscular model to compare spinal loads and muscles recruitments between an unbalanced subject (patient) and a normal volunteer. Data collection was performed and imputed into the muscular model: from sagittal X-rays, together with plantar foot pressure measurements, external loads for the L3/L4 level were calculated. Using MRI of the thoraco-lumbar region and muscular testing, a personalized muscular model was constructed. The main results are as follow: external loads for the unbalanced subject were higher because of the postural default, especially for flexion moment. Running the model, simulations showed a higher erector spinae group activation for the patient. This induced a significant difference in joint compression. Setting the maximum admissible stress of the extensor muscles of the patient to an equivalent level as the one found for the volunteer to maintain the posture, a second simulation was performed. Joint compressi...
Revue de Chirurgie Orthopédique et Réparatrice de l'Appareil Moteur, 2004
Revue de Chirurgie Orthopédique et Traumatologique, 2015
Revue de Chirurgie Orthopédique et Réparatrice de l'Appareil Moteur, 2007
ABSTRACT Introduction L’association de moelle osseuse à la greffe lors des arthrodèses lombaires ... more ABSTRACT Introduction L’association de moelle osseuse à la greffe lors des arthrodèses lombaires est une technique largement utilisée. La moelle apporte des cellules souches et des facteurs de croissance contenus dans les plaquettes, favorables à la repousse osseuse. L’adjonction de moelle osseuse sous sa forme concentrée pourrait en théorie créer des conditions encore plus favorables et majorer la repousse osseuse. Le but de cette étude a été de comparer quantitativement sur des images scannographiques la repousse osseuse entre les sites d’arthrodèse ayant reçu de la moelle osseuse concentrée et ceux ayant reçu de la moelle osseuse non concentrée. Méthode Il s’agissait d’une étude prospective sur 15 patients présentant des lombo-sciatalgies chroniques sur rachis dégénératif. En peropératoire, une fraction de la ponction de moelle osseuse a été concentrée par centrifugation afin de récupérer un concentré de cellules mononucléés (contenant les cellules souches) et de plaquettes. Un coté a reçu ce concentré, l’os de décortication et des céramiques. L’autre coté a reçu le même greffon avec de la moelle osseuse non concentrée. Une analyse quantitative a été réalisée, à l’aide d’un logiciel de mesure semi-automatisé, sur des images scannographiques, permettant de déterminer le volume d’os cortical dans le greffon en postopératoire immédiat et à 3 mois. Les concentrations en cellules souches et en plaquettes dans chaque échantillon de moelle injectée ont été déterminées pour chaque patient par comptage, culture et phénotypage. Résultats L’étude biologique montre un taux de concentration moyen de 6 fois pour les cellules mononucléées et de 3,3 fois pour les plaquettes. La comparaison du volume en os cortical de chaque coté en postopératoire et à 3 mois n’a pas mis en évidence de différence significative. Discussion et conclusion Malgré la concentration effectuée, quantifiée biologiquement, il n’a pas été mis en évidence de majoration de la repousse osseuse en ajoutant de la moelle osseuse concentrée. Cependant, la quantité de cellules souches étant très faible dans la moelle osseuse, il se peut qu’il faille une concentration supérieure à celle que nous avons obtenue pour faire apparaître une différence. De plus, Le problème principal rencontré a été une concentration peropératoire aléatoire de la moelle osseuse. Enfin, la technique de reconstruction 3D du greffon et son analyse se sont montrées efficaces car le calcul du volume du greffon postopératoire a été sensiblement le même chez tous les patients.
Revue de Chirurgie Orthopédique et Traumatologique, 2015
Annals of physical and rehabilitation medicine, 2014
In hemiplegic children the appearance of equinovarus is correlated with premature electromyograph... more In hemiplegic children the appearance of equinovarus is correlated with premature electromyography (EMG) activity of the gastrocnemius medialis (GM) prior to initial contact. The goal was to analyze the onset of EMG activation in the GM and, more particularly, the peroneus longus (PL) in cases of equinovarus: is PL activity likewise premature? As 15 hemiplegic children (age 5 years±1.5) with equinovarus walked, their PL and GM EMG activity was being recorded. The latter was normalized in terms of gait cycle percentage (0-100%) and detected through semi-automatic selection with activation threshold set at 20μV. A paired t-test compared activation onset of the PL versus the GM muscles. As regards the healthy limb, activity onset of the GM (+14.55%) and the PL (+19.2%) muscles occurred only during the ST. In cases of equinovarus, activation of the GM (-5.2%) and the PL (-6.1%) occurred during the SW and was premature. For each muscle, comparison between the healthy and the hemiplegic s...
Journal of Spinal Disorders