Background context: With an increasing prevalence of low back pain, physicians strive to optimize the treatment of patients with degenerated motion segments. There exists a consensus in literature that osteoporotic patients exhibit nonphysiologic loading patterns, while degenerated intervertebral discs (IVDs) are also believed to alter spine biomechanics.
Purpose: To evaluate alterations occurring in lumbosacral spine biomechanics of an osteoporotic model, with or without IVD degeneration, when compared with a healthy spine segment.
Study design: The investigation was based on finite element (FE) analysis of a patient-specific lumbosacral spine model.
Methods: A biorealistic model of a lumbosacral spine segment is introduced to determine the morbidity of disc degeneration and osteoporosis. The model was verified and validated for the purpose of the study and subjected to a dynamic FE analysis, considering anisotropic bone properties and solid ligamentous tissue.
Results: The yielded results merit high clinical interest. Osteoporosis resulted in a nonuniform increase of facet joint loading, which was even more pronounced in the scenario simulating a degenerated disc. The results also revealed an enslavement of intradiscal pressure to the disc state (in the degenerated and superior adjacent level).
Conclusions: The investigation presented refined insight into the dynamic biomechanical response of a degenerated spine segment. The increase in the calculated occurring stresses was considered as critical in the motion segment adjacent and superior to the degenerated one. This suggests that prevalent trauma in a motion segment may be a symptomatic condition of a poorly treated formal pathology in the inferior spine level.
Keywords: Facet loading; Finite element analysis; Intervertebral disc degeneration; Lumbosacral spine; Non-linear model; Spine biomechanics.
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