Solid-State 3D Models of Lumbar Vertebral Segments

Abstract

Background: 3D modeling of human organs and structures could aid the development of new therapies and materials to personalize each patient’s needs. This study aimed to create solid-state 3D models of the vertebral segments and test their deformations and stress state under different circumstances.Methods: 3D finite element computer model of lumbar segments was created and tested for the range of motion and stress patterns generated at the lumbar spine using SOLIDWORKS® Simulation software (https://www.solidworks.com/). The finite-element mesh was developed for this model. It consisted of 52662 elements and 90426 nodes, with 271278 degrees of freedom. Parabolic triangular and tetrad elements with a size of 4.15 mm and a tolerance of 0.2075 mm were utilized. After validation, the model was analyzed under static compression 300N to mimic the vertical position of the body.Results: The following average stress levels were determined in the different components of the model during the test: on the upper vertebra - 9.34±0.11 MPa, on the middle - 10.66±0.10 MPa, and the lower - 8.99±0.09 MPa; on the upper intervertebral disc 0.58±0.01 MPa, and the lower - 0.69±0.01 MPa; on the anterior longitudinal ligament - 0.02±0.001 MPa; on the posterior longitudinal ligament - 0.05±0.001 MPa; on the upper transverse ligaments - 0.01±0.001 MPa, and the lower - 0.04±0.001 MPa; on the interspinous ligaments - 0.02±0.001 MPa, and the supraspinatus - 0.03±0.001 MPa.Conclusions: Modeling static compression showed that the maximum stresses were primarily distributed over the vertebral bodies’ cortical bone and extinguished by the trabecular structure and intervertebral discs. Maximal displacements were found in the annulus fibrosus. Solid-state models with a finite-element mesh can be used for biomechanical investigations in vertebral segments. However, more extensive sample studies with different models may be required to compare movement and loading patterns at different lumbar spine structures.