The article proposes the method for evaluating angular and linear changes in intervertebral discs of the spine depending on linear and nonlinear intervertebral disc stiffness. A dynamic made of 5 solid bodies connected by damping and stiffness components and applied for 2-D 10 degrees of freedom of the lumbar spine has been used for calculations. The system of the equation has been written in a matrix form. Lumbar intervertebral discs stiffness and damping properties have been selected from scientific articles and make from 200 N/mm to 1200 N/mm and from 229 Ns / mm to 5100 Ns/mm respectively for non-linear calculation and 800 N / mm – 2637 Ns/mm for linear displacement calculation. External loads applied to the model are 1648 N, 2957 N, 3863 N and 4542 N. The basic task of the paper is to calculate the biggest difference in linear and angular displacement considering 2 cases: linear and non-linear stiffness value. The greatest estimated difference, under the highest load, makes 0.6 mm for linear and 0.95 degrees for angular displacement. Because of the fast response of the model to the load, the damping value could not affect displacement.

Article in: Lithuanian

Article published: 2015-03-05