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STUDY DESIGN: Descriptive. OBJECTIVES: Trabecular bone in the vertebrae is critical for the distribution of load and stress throughout the neuroaxis, as well as the intervertebral disk, ligamentous complex, and facet joints. The objective was to assess the stress and strain distribution of the L4-S1 spine segment by a finite element analysis. METHODS: A lumbosacral spine model was built based on a CT-Scan. Trabecular-to-cortical bone distribution, ligaments, intervertebral disk, and facet joints with cartilage were included. A perpendicular force was applied over the L4 upper terminal plate of 300 N, 460 N and 600 N in neutral, plus 5 Nm and 7.5 Nm for flexion and extension movements. Maximum principal stress and total deformation were the main studied variables. RESULTS: Trabecular bone confers resistance to axial loads on the vertebrae by elastic capacity and stress distribution. MPS and TD showed axial stress attenuation in the nucleus pulposus and longitudinal ligaments, as well as load distribution capacity. Facet joints and discontinuous ligaments showed greater TD values in flexion moments but greater MPS values in extension, conferring stability to the lumbosacral junction and axial load distribution. CONCLUSION: We propose 3 anatomical systems for axial load distribution and stress attenuation in the lumbosacral junction. Trabecular bone distributes loads, while the ligamentous-intervertebral disk transmits and attenuate axial stress. Facet joints and discontinuous ligaments act as stabilizers for flexion and extension postures. Overall, the relationship between trabecular bone, ligamentous-intervertebral disk complex and facet joints is necessary for an efficient load distribution and segmental axial stress reduction.This slide can be retrieved from the Global Spine Congress 2023.
RESUMO
Introducción: las alteraciones en la función ejecutiva, especialmente en flexibilidad cognoscitiva, planeación,control inhibitorio y memoria de trabajo constituyen un elemento cardinal dentro las manifestaciones deltrastorno del espectro autista (TEA).Objetivo: el objetivo de este trabajo fue evaluar el desempeño de las pruebas de función ejecutiva en unapoblación de pacientes con trastorno del espectro autista (TEA).Materiales y métodos: se realizó un estudio observacional en niños de una institución de rehabilitación. Seevaluó el desempeño en las subpruebas de la evaluación neuropsicológica infantil, el puntaje de CARS (ChildhoodAutism Rating Scale) y otras variables, mediante un análisis de correlación de Spearman. El estudio fueaprobado por el Comité de Ética en Investigación y se obtuvo consentimiento de los padres.Resultados: se evaluaron ocho niños con edad promedio de 8,9 años (6,1-13,7) y puntaje CARS entre 32 y 46.Se encontró mejor desempeño en habilidades gráficas y menor fluidez gráfica y verbal y de flexibilidad cognitiva.La edad tuvo correlación directa con el puntaje en memoria de trabajo y con la capacidad de planeación.Un puntaje de CARS alto se correlacionó con bajo rendimiento en flexibilidad cognitiva, memoria de trabajoy fluidez gráfica no semántica.Conclusión: los niños con TEA son susceptibles de presentar alteraciones significativas en tareas relacionadascon las funciones ejecutivas, lo que puede explicar la tendencia a la perseveración, incapacidad de cambio decriterio y conductas estereotipadas. Esta disfunción se correlaciona con la severidad del autismo y varía segúnla edad. Aunque esta alteración no es un fenómeno que se presente exclusivamente en el TEA, constituye unelemento a tener en cuenta al momento de evaluar estos niños.
Introduction: executive function disturbances, especially in cognitive flexibility planning, inhibitory control and working memory constitute a cardinal element within the manifestations of autism spectrum disorder (ASD).Objective: the aim of this research was to evaluate the performance of executive function tests in children with ASD.Materials and methods: an observational study was conducted in children attending a rehabilitation institution. An analysis between the performance of the Childhood Neuropsychological assessment subtests, scores of CARS (Childhood Autism Rating Scale) and other variables was performed by a Spearman correlation test. The study was approved by the Institutional Ethics Committee and parental consent was obtained.Results: we evaluated eight children with a mean age of 8.9 years (min: 6.1, max: 13.7) and CARS score between 32 and 46. Better performance was found in graphical abilities, less in graphical and verbal fluency and in cognitive flexibility. Age was directly correlated with scores on working memory and planning. A high CARS score was correlated with poor performance on cognitive flexibility, working memory and non-semantic graphic fluency.Conclusion: children with ASD are prone to show disturbances in executive functions related tasks which may explain the inflexible adherence to routines, the persistence of stereotypical behaviors and the perseveration observed in ASD patients. This dysfunction correlates with the severity of autism and varies with age. Although this condition is not present exclusively in ASD, it is a factor to consider when evaluating children with autism.