Abstract

Background: Involvement of the vertebral components with tumor may be followed by spinal compression, however the degree of spine instability depends on various factors such as vertebral level and damage configuration. This study aimed to assess the mechanism of a severe spinal compression in an anteroposteriorly tumor-involved lumbar vertebra using the computational models.
Methods: The strategy was simulation of a vertebral segment damaged by multiple myeloma using a verified FE model and then comparison of the deformations, estimated by the model, with MRIs. Progression and propagation of the tumor were simulated using a virtual thermal flux and conductivity, based on a valid scenario, reported in the literature. The FE model, associated with the healthy state of the vertebral segment, was verified by comparison of its estimations for load carrying shares by the various vertebral components with these values, demonstrated in prior In-Vitro tests.
Results: Estimation of the FE model from deformations and spinal compression through progression of the disease was promising. The precedence of the softening in the posterior half of the vertebral body caused an extra backward rotation and increase of the load carrying share by the posterior elements of the damaged vertebra equal to 58%, known as stress-shielding. Diffusion of the osteolytic damage to the posterior elements of the vertebra was followed by instability and compression of the spine.
Conclusion: Determination of a sequential propagation of tumor in the anteroposteriorly osteolytic lumbar vertebra for the FE model according to the patterns, proposed by the prior studies, was enough to simulate spinal compression. This model could estimate the amount of secondary bending moment on the posterior elements of the damaged vertebra due to stress-shielding and osteolytic damage.

Keywords:Spinal compression; Tumor progression; Lumbar vertebrae; Stress-shielding; Multiple myeloma