Characteristics of Nerve Roots Mechanical Properties Exposed to Uniaxial Stretching Tests

The article presents the problem of the mechanical response of nerve roots under stretching conditions. Research into the functioning of the nervous system shows a relation between deformation, blood flow characteristics, and nerve root impulse transmission. These studies show that vascular hypofusion of peripheral nerves occurs at a deformation of 15%. It is also known that impulse conduction disturbances occur at 6% strains. This calculation shows that one of the causes of diseases of the nervous system may be excessive deformation of its structures. One such disease is radiculopathy. Understanding the mechanical response of tissues exposed to damaging conditions requires computations from complex constitutive models that cannot be solved analytically. Therefore, the properties of the tissue material are investigated using numerical approximation methods. For this purpose, it is necessary to experimentally study the properties of the material that allow to determine the parameters of the numerical models used. The aim of the research was to determine the material properties of nerve roots. The analysis was carried out in order to obtain data that would simulate the conditions of the development of nerve root diseases. Modelling was performed using the Finite Element Method (FEM). Mechanical properties were determined on the basis of uniaxial stretching of the nerve roots of the rabbit’s lumbar spine on a testing machine. The tests showed that the rabbit’s nerve root strength is 0.9 ± 0.53 MPa, the relative deformation is 12.73 ± 4.03%, and the Young’s modulus is 2.53 ± 1.00 MPa. The results show the range of strength and stiffness values for various species of animals and humans. The conducted research has shown that the sample preparation procedure has an important influence on the obtained values.