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Content available remote Mechanical properties of cervical dura mater
The aim of the study was to determine experimentally the stress as strain function as well as the orthotropy and heterogeneity of porcine dura mater of the cervical spinal cord. Material was divided into groups based on the place of collection, considering the dorsal side and ventral side, specifying the number of cervical vertebra, and the direction of tension of the sample - longitudinal or circumferential. Experimental studies were conducted with the MTS Synergie 100 testing machine. The tensile test was performed for each sample at a speed of 2 mm/min until the sample's break. There were determined the characteristics of stress as a function of strain in particular samples. Distribution maps of the stress and strain values at the characteristic points were then drawn (the beginning and the end of the linear range of the stress-strain characteristic and the point corresponding to the complete sample damage) for each set of samples, taking account of their collection place and direction of tension. The results confirmed the orthotropy of mechanical properties of dura mater. Stress and strain differed also in the value at the height of each vertebra and exhibited diversification on the ventral side compared to dorsal one.
Content available remote Finite element modelling of the cervical spinal cord injury - clinical assessment
The aim of the study was to evaluate the efficiency of Finite Element Method (FEM) modelling of the clinical cases of traumatic cervical spinal cord injury (SCI). The study population consisted of 28 patients suffering from traumatic cervical spine injury with (study group) and without (control) neurological deficits. A numerical simulation of the trauma event was performed, based on validated 3D FEM model. All the results obtained underwent statistical analysis. Statistically significant differences between both groups were found in severity of bony and neural structure damage as well as in stress and strain ratios. The highest values of tensile stress and deformation were noted in the sagittal (Y) axis. The maximum stress and strain were found in anterior spinothalamic, lateral spinothalamic and dorsal columns. It was also found that stress and strain in each segment and axis of the spinal cord model were positively correlated with the severity of the cervical spine injury (R-Spearman 0.39 to 0.64) and neurological symptoms of SCI (R-Spearman: 0.43 to 0.82). It is possible to create a clinical numerical model of the SCI with the use of FEM. The correlations between the mechanical force and neurological deficits show tendencies which require further studies based on an improved model and a greater number of patients.
Content available remote Numerical model of the human cervical spinal cord - the development and validation
The influence of mechanical load on the extent of nervous tissue damage in the spinal cord at the time of trauma is presently incontestable. Although numerical modelling cannot fully replace physical testing, it seems to be the perfect complement to experiments in terms of the analysis of such a complex phenomenon as traumatic spinal cord injury. Previous numerical models of the human cervical spinal cord have been limited by several factors: two-dimensional modelling, spinal cord geometry simplification and incomplete reflection of specific anatomical and biomechanical relations of the objects being modelled. The objective of this study was to develop and validate an accurate and universal numerical Finite Element Method (FEM) model of the human cervical spinal cord. Our survey focuses mainly on geometric, constraint and material aspects. Experimental validation was carried out based on a controlled compression of the porcine spinal cord specimens. Each stage of compression was simulated using the FEM model of the compressed segment. Our 3D numerical simulation results compared with experimental results show a good agreement. It is possible to use the developed numerical model of the human cervical spinal cord in the biomechanical analysis of the spinal cord injury phenomenon. However, further clinical evaluation is clearly justified.
According to up-to-date knowledge only mathematical modelling of the spinal cord injury (SCI) may provide real insight into a spatial location of the fields of the spinal cord mechanical strain generated by the injury. The purpose of our research was to correlate the results of Finite Element Analysis of SCI with the patient’s neurological state and the injured spinal cord MR imaging. The 3D Finite Element Model of the cervical spinal cord and vertebral canal of a 21-year-old male patient was created. The moment of the injury was reconstructed by a simulation of the displacement of nonelastic structure to the light of vertebral canal. A detailed spatial analysis of the stress, strain and dislocation distribution was performed. The most injured region was the superficial zone of the white matter, the anterior part and central region of the grey matter, which was in good agreement with patient’s neurological staus. An individualized Finite Element Model of traumatic SCI constructed by us enabled the evaluation of the influence of mechanical strain on a neurological condition of a patient. Further research will consist in validation of the results of endurance analyses based on a enlarged group of patients.
Niniejsza praca stanowi przegląd literaturowy metod, sposobów, a także materiałów stosowanych oraz będących w sferze badań do konstrukcji protez do regeneracji obwodowego układu nerwowego. Zawiera również opis anatomicznych i fizjologicznych procesów przebiegających podczas regeneracji nerwów, a także zestawienie ich własności biomechanicznych.
The work presents the state of the art in the area of methods and materials used in peripheral nerve treatment. Anatomical and physiological aspects of peripheral nerves their biomechanical properties and their treatment are presented.
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