Mathematical modeling of biomechanics of the lumbar spine with a decrease in bone mineral density after the use of stabilizing systems

We describe the mathematical modeling of the lumbar spine with reduced bone mineral density using the finite element method (FEM). The main focus is based on the comparison of the biomechanical characteristics of two stabilization systems: rigid interlaminar stabilization (RIS) and transpedicular fixation (TPF). Methods: The study was performed by mathematical modeling using the finite element method (FEM) to assess the distribution of stresses and deformations during transpedicular fixation (TPF) and rigid interlaminar stabilization (RIS). The data were compared to computer tomography of patients, anatomical features of vertebras and characteristics of bone tissue. The biomechanical effects of stabilization systems were evaluated under various types of loads corresponding to physiological conditions: axial load: imitation of vertical load in a standing position (50 kgf). Flexion and extension: modeling the flexion and extension of the spine. Lateral inclinations: lateral inclinations taking into account the asymmetric load on the intervertebral discs and ligaments. Twisting: rotational loads with assessment of implant stability. Results: It was revealed that transpedicular fixation is accompanied by increased loads on adjacent vertebrae, which increases the risk of adjacent segment syndrome. Rigid interlaminar stabilization allows more adequate distribution of loads, but increases stress in the arches of the vertebrae. Our data are consistent with the results of studies, confirming the need for an individual approach to the choice of a stabilization method in patients with osteoporosis. Conclusions Rigid interlaminar stabilization is preferred for patients with osteoporosis, while transpedicular fixation remains the standard for severe instability.